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Pilot scale struvite recovery trials from a full-scale anaerobic digester supernatant at the City of… Britton, Ahren Thomas 2002

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PILOT S C A L E S T R U V I T E R E C O V E R Y T R I A L S F R O M A F U L L - S C A L E A N A E R O B I C D I G E S T E R S U P E R N A T A N T A T T H E C I T Y OF P E N T I C T O N A D V A N C E D W A S T E W A T E R T R E A T M E N T P L A N T A H R E N THOMAS BRITTON B.A.Sc. (Environmental Engineering (Civil)), University of Waterloo, Canada, 2000 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE D E G R E E OF M A S T E R OF APPLIED SCIENCE in THE F A C U L T Y OF G R A D U A T E STUDIES DEPARTMENT OF CIVIL ENGINEERNJG We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH C O L U M B I A June 2002 © Ahren Thomas Britton, 2002 In p resen t i ng this thesis in partial fu l f i lment of the requ i remen ts for an a d v a n c e d d e g r e e at t he Un ivers i ty of Br i t ish C o l u m b i a , 1 agree that the Library shal l m a k e it f reely avai lable for re fe rence and s tudy. I fur ther agree that pe rm iss i on for ex tens ive c o p y i n g o f th is thes is fo r scho lar ly p u r p o s e s may b e gran ted by the h e a d of m y d e p a r t m e n t o r by his o r her representat ives. It is u n d e r s t o o d that c o p y i n g o r p u b l i c a t i o n of th is thesis for f inancia l gain shal l no t b e a l l o w e d w i t hou t m y wr i t ten p e r m i s s i o n . D e p a r t m e n t of Oil/it ^hai***^r\« T h e Univers i ty of Brit ish C o l u m b i a V a n c o u v e r , C a n a d a D A T E J ' . L . / . ^ ^ V > 7 -D E - 6 (2/88) A B S T R A C T ABSTRACT Pilot-testing of a fluidized bed reactor used to recover phosphate in the form of struvite from a full-scale anaerobic digester supernatant was conducted on site, at the City of Penticton Advanced Wastewater Treatment Plant (AWWTP). The main objective of this study was to demonstrate the ability of the reactor, developed by the U B C phosphate recovery team, to remove at least 70 % of the phosphate in the supernatant from a full-scale digester fed with a combination of primary and secondary sludge, from a biological nutrient removal wastewater treatment plant. Results showed that the reactor was capable of removing over 80 % of the phosphate from the digester supernatant. The operation of the reactor could easily be controlled to achieve any desired level of phosphorus removal up to 90%. Reactor operation was relatively trouble free after an initial commissioning period. By the end of the experiment, it was possible to leave the reactor unattended for periods of up to 5 days without incident. Analysis of the recovered struvite crystals showed essentially pure struvite (>99 % by weight) with small amounts of calcium (<0.5 % by weight) and traces of potassium and iron. The recovered crystals had mean diameters increasing from 0.5 to 1.8 mm over the course of the study. This increasing diameter is believed to be due to changes in the crystal structure that caused them to become stronger over the course of the study. The causes of this change in crystal structure remain unknown, and require further investigation. A model was developed which was able to predict the effluent quality of the reactor based on the concentrations of magnesium, ammonia and phosphate in the reactor influent and the operating pH of the reactor. The model is based on the assumptions that the reactor effluent is at equilibrium with respect to struvite, and that magnesium, ammonia and phosphate are removed in equimolar amounts. The system equilibrium was described by an equilibrium conditional solubility product curve, developed for a sample of digester supernatant taken during the study. i i A B S T R A C T Phosphate release from the anaerobic digestion of waste activated sludge was found to be 13% of the total phosphorus load to the treatment plant, when digesting only 40% of the secondary sludge, significantly lower than predicted in a previous study (Niedbala, 1995). This is probably due to the recent practice of discharging aluminum-rich sludge from the city drinking water treatment plant to the wastewater treatment plant. Changing this practice could result in the production of significantly greater masses of product at similar costs, thus increasing the economic viability of the process. Further studies at larger scale and of longer duration would be required to determine the steady state struvite product qualities produced by this process. The market that the product will target will also be important in order to produce a desirable and profitable product. i i i T A B L E O F C O N T E N T S TABLE OF CONTENTS Page Abstract « TABLE OF CONTENTS iv LIST OF TABLES vii LIST OF FIGURES viii ACKNOWLEDGEMENTS x 1. Introduction 1 1.1. Global Phosphorus Supply Depletion . 1 1.2. Recoverable Phosphorus Sources In British Columbia 2 1.3. Site Selection 2 1.4. City of Penticton Advanced Wastewater Treatment Plant 3 2. Research Objectives 4 3. Background _____ 5 3.1. Struvite Chemistry 5 3.2. Struvite Crystallography : 6 3.3. Struvite Formation Models 8 3.4. Operating Problems at Wastewater Treatment Plants 10 3.4.1. Phosphorus Release During Anaerobic Digestion 10 3.4.2. Struvite Encrustation 11 3.4.3. Excess Sludge Production for P Removal__ 12 3.5. Feasibility of Struvite Recovery from Wastewater 13 3.6. Pilot and Full-scale Struvite Recovery Studies 15 4. Materials and Methods 18 4.1. Reactor Design 19 4.1.1. Inj ection Port Design ______________ 21 4.1.2. Harvest Zone Des ign 22 4.1.3. Reaction Zone Design 22 4.1.4. Clarifier Zone Design 23 4.1.5. External Clarifier and Recycle F l o w 24 4.1.6. Supernatant Storage Tanks and Supernatant Feed F l o w : 26 4.1.7. p H Control and Caustic Soda Dosing 27 4.1.8. Magnes ium Chloride Dosing 29 4.1.9. Crystal Harvest Procedure 30 4.1.10. Crystal Dry ing and Analysis 30 4.1.11. D a i l y Moni tor ing and Control • 31 4.2. Struvite Solubility Determination 32 iv T A B L E O F C O N T E N T S Page 4.2.1. Apparatus 32 4.3. Crystal Product Analysis 33 4.4. Analytical Methods 34 4.4.1. Magnes ium 34 4.4.2. Ortho-phosphate 35 4.4.3. A m m o n i a 35 4.4.4. p H 36 4.4.5. Ca lc ium, A l u m i n u m and Iron 36 4.4.6. Potassium 36 4.4.7. Total Phosphorus 36 4.4.8. Filtration 37 4.4.9. Conductivity 37 4.5. Terminology 37 4.5.1. Struvite Solubil i ty Product 37 4.5.2. Struvite Conditional Solubil i ty Product 39 4.5.3. Supersaturation Ratio 39 4.5.3.1. Feed supersaturation ratio 40 4.5.3.2. Effluent supersaturation ratio 40 4.5.3.3. In-reactor supersaturation ratio 40 4.5.4. Recycle Ratio 41 4.5.5. Crystal Retention Time 41 4.5.6. M e a n Crystal Size 41 4.5.7. Percent Phosphate Removal 42 Results and Discussion 43 5.1. Struvite Solubility Product Determination 43 5.1.1. Struvite Solubil i ty Product in Dis t i l led Water 44 5.1.2. Struvite Solubil i ty Product in Digester Supernatant 45 5.1.3. Struvite Conditional Solubili ty Product 45 5.2. Supernatant Characteristics During the Study 46 5.3. Reactor Operation 48 5.3.1. M g / N H 4 / P 0 4 Forms and filtration 49 5.3.2. Removal efficiency 50 5.3.3. Struvite Recovery 54 5.3.4. Reactor Struvite Loading 55 5.3.5. Supersaturation Ratio 56 5.3.5.1. Relation between in-reactor and effluent SS ratios 57 5.3.6. Crystal Retention Time 61 5.3.7. Operational Problems 62 5.3.7.1. Plugging o f tubing 62 5.3.7.2. Reactor fouling 63 5.3.7.3. Injector port fouling 63 5.3.7.4. Feed flow regulation 63 5.3.7.5. Suspended solids control 64 5.3.7.6. Caustic solution storage and strength depletion 64 5.3.7.7. Magnesium chloride dosing rate 64 5.4. Reactor Performance Model 65 5.5. Struvite Product Characteristics 70 v T A B L E O F C O N T E N T S Page 5.5.1. Struvite Crystal Size 70 5.5.2. Struvite Crystal B u l k Density 73 5.5.3. Struvite Crystal Composit ion 74 5.5.4. Microscope and S E M Crystal Examination 75 5.6. Treated Supernatant Phosphate and Ammonia Reductions 81 5.6.1. A m m o n i a L o a d form the Digester Supernatant 82 5.6.2. Phosphorus Load F r o m the Digester Supernatant 82 5.6.3. Estimated Full-scale Struvite Production 83 5.7. Financial Estimates 83 5.7.1. Capital Infrastructure Requirements 83 5.7.1.1. Digester upgrade 83 5.7.1.2. W A S dewatering and transfer to digester 84 5.7.1.3. Supernatant transfer to settling and storage 84 5.7.1.4. Supernatant settling and storage , 84 5.7.1.5. M g C l storage, batch dilution and dosing , 84 5.7.1.6. N a O H storage, batch dilution and dosing 85 5.7.1.7. Reactor feed and recycle pumps with flow control 85 5.7.1.8. Struvite crystallizing reactor 86 5.7.1.9. Chemical injector section , 86 5.7.1.10. Product screening and drying 86 5.7.1.11. Product packaging andshipping 87 5.7.2. Operating Costs . . 87 5.7.2.1. Chemica l costs 87 5.7.2.2. Labour costs 88 5.7.3. Savings and Revenues 88 5.7.4. Net Process Savings 89 6. Summary and Conclusions 90 7. Recommendations 92 8. References 94 Appendix A: Instrument Operational Parameter Details 99 Appendix B: Ksp Determination Data and Calculations 100 Appendix C: Operating Data for Reactor A 109 Appendix D: Operating Data for Reactor B 130 Appendix E: Model Results 151 Appendix F: Crystal Chemical Analysis 160 Appendix G: Operating Cost Estimates 167 v i L I S T O F T A B L E S LIST OF TABLES Page Table 5.1: Supernatant filtration analysis and solid fraction 49 determination for reactor influent and effluent. Table 5.2: Comparison of theoretical struvite production and actual 55 struvite recovery. Table 5.3: Comparison of average model error absolute and actual 70 values. Table 5.4: Average results of crystal composition analysis. 74 Table 5.5: Struvite crystal impurity content. 75 Table 5.6: Chemical costs. 88 Table 5.7: Cost savings and revenues. 88 Table 5.8: Overall process savings for full-scale struvite recovery. 89 v i i L I S T O F F I G U R E S LIST OF FIGURES Page Figure 4.1: Pilot-scale reactor setup at the City of Penticton AWWTP. 18 Figure 4.2: Pilot-scale struvite crystallizer reactor process design. 20 Figure 4.3: Pilot-scale struvite crystallizer injection port assembly. 21 Figure 4.4: Pilot-scale reactor layout. 25 Figure 4.5: Fibrous residue from crystal dissolution tests. 34 Figure 5.1: Struvite solubility product in distilled water and digester 45 supernatant vs. sample pH. Figure 5.2: Struvite pPs in digester supernatant and distilled water as a 46 function of pH Figure 5.3: Digester supernatant composition during the course of the 47 study. Figure 5.4. Percentage phosphate removal for each reactor during the 51 study period. Figure 5.5: Phosphate removal vs. operating pH in the struvite 52 crystallizing reactors. Figure 5.6: Phosphate removal vs. inlet supersaturation ratio in the 53 struvite crystallizing reactors. Figure 5.7: Percentage ammonia removal for each reactor during the 54 study period. Figure 5.8: Reactor struvite loading during the study period. 56 Figure 5.9: Reactor A supersaturation ratios during the study period. 57 Figure 5.10: Reactor B supersaturation ratios during the study period. 57 Figure 5.11: Comparison of in-reactor SS ratio with effluent SS ratio 58 for Reactor A . Figure 5.12: Comparison of in-reactor SS ratio with effluent SS ratio 58 for Reactor B . Figure 5.13: The relationship between the in-reactor and effluent 60 supersaturation ratios. viii Figure 5.14: The relationship between reactor struvite loading rate and effluent supersaturation ratio. Figure 5.15: CRT calculated for all harvested crystals during the study period. Figure 5.16: Modeled and actual effluent phosphate concentrations for Reactor A . Figure 5.17: Modeled and actual effluent phosphate concentrations for Reactor B Figure 5.18: Modeled and actual effluent ammonia concentrations for Reactor A . Figure 5.19: Modeled and actual effluent ammonia concentrations for Reactor B Figure 5.20: Modeled and actual effluent magnesium concentrations for Reactor A . Figure 5.21: Modeled and actual effluent magnesium concentrations for Reactor B. Figure 5.22: Mean crystal diameter of struvite crystals harvested during the study. Figure 5.23: Mean harvested crystal diameter vs. CRT for each harvest. Figure 5.24: Mean harvested crystal diameter vs. CRT averaged in-reactor SS ratio. Figure 5.25: Harvested crystal mass from the 1.1L harvest zone over the course of the study. Figure 5.26: S E M images of crystals retained on a 1 mm sieve, but passing a 2 mm sieve at 5 OX magnification. Figure 5.27: S E M images of crystals harvested from Reactor B on December 11 at 50X magnification. Figure 5.28: S E M images of a crystal retained on the 1 mm sieve, harvested from Reactor B on Dec 11. A C K N O W L E D G E M E N T S ACKNOWLEDGEMENTS I would like to acknowledge the assistance, support and encouragement that have been provided by the following people and organizations, without which this research would not have been possible: • Fred Koch, the father of the U B C phosphate recovery team, for paving the way and for continued direction throughout this study. • Don Mavinic, my research supervisor, for his support and direction. • City of Penticton AWWTP Staff: Karen, Brian, Berne, Cid, Eric, Gary, Bob, Rob, Harry, Randy and Darryl, for their wholehearted support of this study. • A l i Adnan, the other half of the pilot-scale research team, for helping with analytical work and sharing ideas. • Ping Liao, the team chemist, for help with solubility determinations, and for being a good sounding board. • Mahazareen Dastur, the pioneer student in this research group, for laying the groundwork that made the success of this research possible. • Laurelle Perfanick at B C Hydro, for helping to develop a market for this technology. • Paula Parkinson, for her help with analytical work, and lab disorientation. • Susan Harper, for her help and instruction in the lab. • Daniel Potts, for the S E M images of my crystals. • To my family and friends for their encouragement and support throughout my degree. • BC Hydro, for their generous funding of this research project. • NSERC, for supporting my research through a PGS scholarship. • U B C , for giving me this opportunity, and for supplementing my funding. • Stantec Consultants, for funding my accommodations during the field study in Penticton. • City of Penticton, for the use of their facilities, and for their vision of the potential for this research. • Thunder Sword Resources Inc., for supplying magnesium chloride and helping to develop a market for this technology. To Katherine who became my bride during this endeavor I N T R O D U C T I O N 1. INTRODUCTION Phosphorus recovery is an important area of research in the environmental engineering field. There are a variety of reasons for this, including the gradual depletion of global reserves of mined phosphate deposits, the degradation of the quality the remaining phosphate ore and operational problems encountered in biological nutrient removal (BNR) wastewater treatment plants. The piping and equipment in the sludge treatment processes of these plants is increasingly prone to fouling and encrustation with struvite, which can dramatically increase pumping and maintenance costs. Another important factor in driving this research was the increased opportunity for phosphate recovery derived from the increased use of biological nutrient removal technology around the world. The use of B N R in wastewater treatment leads to the creation of an enriched phosphate stream in the sludge handling liquors. This enriched stream was the focus of most investigations into the recovery of phosphorus from municipal wastewaters. In this study, a pilot scale phosphorus recovery reactor, developed at the University of British Columbia, was tested at a full-scale B N R treatment plant in the city of Penticton, British Columbia, Canada. The reactor was used to recover phosphate in the form of struvite (MgNH4PO4»6H20) from an anaerobic digester supernatant stream, through the addition of magnesium chloride and pH adjustment in a fluidized bed. The study was carried out over a four-month period in the fall of 2001, during which time the anaerobic digester was fed with a blend of primary and secondary sludge. The following section outlines the reasons for undertaking this research. 1.1. Global Phosphorus Supply Depletion Studies have shown that the global supply of phosphate rock may be exhausted within the next 50-100 years (Steen, 1998; Driver et al., 1999). The quality of this mined phosphate rock is also decreasing as lower grade ore deposits are used; these contain less phosphorus and more contaminants, such as heavy metals (Driver et al., 1999). For these reasons, the processing of mined phosphate rock is becoming more costly and the phosphate industry is searching for more 1 I N T R O D U C T I O N sustainable and lower cost sources of phosphorus: A study conducted in Europe has found that the phosphate recovered from wastewater was likely to be of better quality than commercially available phosphate rock, but the full economic impact of phosphorus recovery from wastewater still requires further investigation and appears to be site specific (Jeanmaire and Evans, 2001). 1.2. Recoverable Phosphorus Sources In British Columbia In British Columbia the two major sources of phosphorus recovery being considered are municipal wastewater treatment plants and large livestock farms. The main emphasis thus far has been on the municipal wastewater, since there is currently centralized treatment for large volumes of wastewater and commercially exploitable masses of phosphorus can be recovered from single sources. Many wastewater treatment plants are ideal locations for phosphorus recovery since the required pre-treatment and stream concentration to make phosphorous recovery most feasible are already in place. Although the bulk of potentially recoverable phosphate in British Columbia will likely come from agricultural sources in the long run, until regulation are put into place to limit nutrient discharges from farms, it is unlikely that the agricultural industry will invest in the necessary infrastructure to support phosphorus recovery. It is currently estimated that about 1900 tonnes of phosphorus are amenable for recovery per year from municipal sewage in British Columbia and about 10,000 tonnes of phosphorus are recoverable from agricultural wastes (Yu, 2001). 1.3. Site Selection The City of Penticton Advanced Wastewater Treatment Plant (AWWTP) was selected as the site for this experiment. This site was selected because it was one of the nearest BNR plants to the University of British Columbia and has previously been used in successful collaborative research efforts between U B C , the City of Penticton and Stantec Consultants. The AWWTP is also one of the best performing cold climate B N R plants in North America, and the staff has been extremely helpful in previous research conducted on site. The City of Penticton has also expressed an interest in being one of the pioneering municipalities in Canada with regards to implementing innovative and sustainable waste management strategies. 2 I N T R O D U C T I O N 1.4. City of Penticton Advanced Wastewater Treatment Plant The City of Penticton AWWTP consists of preliminary treatment including screening and degritting, primary clarifiers, two parallel modified UCT design B N R secondary treatment trains, sand filters for secondary effluent polishing and chlorine disinfection. The city of Penticton is located in the Okanagan Valley in south central British Columbia, between Lake Okanagan and Lake Skaha. This is a region of intense fruit growing and irrigation and an environment sensitive to excessive nutrient input. For this reason the wastewater treatment plant is subject to very low effluent phosphorus standards (0.25 mg/L). The sludge treatment train for this plant consists of primary sludge fermenters, to provide the required volatile fatty acids for the B N R system, and a two stage anaerobic digester for the fermented primary sludge. The primary sludge is then dewatered on a belt press after being combined with thickened waste activated sludge from the B N R trains. The secondary sludge is not digested on site, since this practice would lead to the release of the excess phosphorus stored in the secondary sludge from the B N R system (Niedbala, 1995). Instead, the combined dewatered sludge is windrow composted off site at the municipal landfill, and the composted sludge is sold to local landscaping and agricultural operations, as a soil conditioner, known as City of Penticton Compost. During the course of this study, from September to December 2001, the operation of the sludge treatment system was modified to transfer a portion of the secondary sludge to the digester, in order to obtain a digester supernatant stream rich in phosphate and ammonia. 3 R E S E A R C H O B J E C T I V E S 2. RESEARCH OBJECTIVES The purpose of this study was to provide the transition for the U B C phosphate recovery team from using synthetic supernatant to using real supernatant at a full-scale B N R wastewater treatment plant. The research team at U B C had successfully demonstrated a reactor design used to recover struvite from synthetic supernatants with Mg, NH4 and PO4 concentrations similar to those expected in the digester supernatant at the City of Penticton A W W T P ; however, some doubts still remained as to the effects of dissolved constituents, as well as suspended solids, in the real supernatant on the control and operation of the reactor. Both bench scale and pilot scale experiments had been conducted at U B C prior to this study, and the expected operating parameters were determined from this work prior to setting up the pilot plant at the City of Penticton A W W T P (Dastur, 2001). The objectives of this study were to determine the operational parameters that would allow successful operation of the pilot-scale reactors treating real anaerobic digester supernatant from a full-scale B N R wastewater treatment plant. Successful operation was defined as the controlled removal of at least 70 % of the ortho-phosphate from the digester supernatant, and the recovery of this phosphorus in the form of large (>lmm) and easily separable struvite crystals. This study also aimed to develop a mathematical model which could be used to predict the pilot-scale reactor performance with respect to treated effluent quality based on an analysis of the untreated supernatant. Other aims of this study were to estimate the impacts of a full-scale struvite recovery plant on nitrogen and phosphorus loads from the digester supernatant, to estimate the production of struvite and to determine the associated costs. 4 B A C K G R O U N D 3. BACKGROUND 3.1. Struvite Chemistry Struvite is a sparingly soluble compound composed of equimolar amounts of magnesium, ammonia and phosphate, as well as six waters of hydration (MgNH 4 P04*6H 2 0). Several studies have been aimed at determining the equilibrium solubility product of this compound in water; however, the results of these studies vary greatly. Dastur (2001) gives a good overview of the work completed on this subject to date. In general, the mixing conditions and assumed times to reach equilibrium vary considerably in these studies, as do the number and complexity of the compounds included in the equilibrium calculations (Ohlinger, 1999). Some studies do not account for the ionic strength of the solutions, while others do, and some studies include varying numbers of magnesium phosphate compounds, while others assume that different forms of phosphate are involved in the formation of struvite (Ohlinger et al., 1998, Dastur, 2001). Overall, the published values for the thermodynamic solubility product (K s p ) of struvite range from 3.8*10"10 to 5.1*10"15 (Dastur, 2001). Uncertainty about the thermodynamic solubility product for struvite has led investigators to develop a surrogate parameter referred to as the conditional solubility product (Ps) which represents the product of the measured total concentrations of the three species involved in the formation of struvite. This simplified analysis only requires the results from the chemical analysis of the sample, but the equilibrium value varies with pH, temperature and possibly other factors (Dastur, 2001). It is, however, simple to develop an equilibrium P s curve for a given sample matrix, that should be applicable in the operation of a struvite crystallizing reactor. The advantage of the use of this P s curve over a true thermodynamic equilibrium constant is that the P s curve is much simpler to develop and use. Only measurements for magnesium, ammonia, ortho-phosphate and pH are required, and no other equilibrium constants or activity corrections are needed. The conditional solubility product curves developed by Dastur (2001) B A C K G R O U N D and Ohlinger (1999) are easily regressed, using second or fourth order polynomial functions, and are therefore easily incorporated in a model to predict the formation of struvite or the operation of a struvite recovery reactor. The main disadvantage of using the P s values for describing a struvite crystallizing system is that comparison between studies becomes more difficult due to differing matrix effects in each wastewater analyzed. A very close agreement was found however between the results of Ohlinger (1999) and a study performed at U B C using distilled water and relatively pure crystalline struvite (Dastur, 2001). 3.2. Struvite Crystallography Several studies have been conducted in order to determine the effects of various environmental conditions on the morphology of struvite crystals. This include the effects of turbulence, struvite supersaturation ratio in the solution, molar ratios of Mg:N:P, presence of impurities, reactor seeding conditions and pH, among others. Overall the morphologies of the crystals vary as widely as the conditions under which they are grown. A n attempt is presented here to summarize some of the more important factors that are thought to affect the shape and size of the produced struvite crystals. Generally, the distinction between precipitation and crystallization reactions is vague. Precipitation is generally used to describe processes that produce small amorphous solids while crystallization is used to describe processes that produce solids with defined structure and crystalline facets. Mersmann (1999) shows that in continuous crystallizers such as the one used in this study, the conditions necessary to produce large particles (which he defines as > 100 pm) is to use low concentration reactants, to encourage agglomeration, to have good macro-mixing in the reactor, and to have low supersaturation ratios. Mersmann also shows that, in crystallizers producing large particles, the primary factor influencing formation of new crystal nuclei tends to be attrition (or breakage of existing crystals) due to impact with reactor components or other crystals. 6 B A C K G R O U N D Spontaneous struvite crystal accumulation in sludge piping and pumping equipment is a problem in wastewater treatment plants, especially those with biological phosphorus removal. This phenomenon was first reported by Borgerding (1972). Struvite accumulation is preferentially formed on rough surfaces, in areas of high turbulences, and in areas that undergo pressure drops (Ohlinger et al, 1999). This is due to ease of surface attachment, bulk chemical transport limitations to the growth of struvite, and pH increases in low pressure areas due to degassing of carbon dioxide. The degree of turbulence in which crystals are grown also has been shown to affect the shape of the crystals. Large, elongated crystals are typically found in quiescent environments whereas small, tightly packed crystals are found in higher mixing energy environments (Ohlinger et al., 1999). In other studies on struvite crystallization, several authors have found interesting relations between various factors and crystal morphology. Particle size uniformity and distribution has been reported to vary with operating pH as well as Mg:P molar ratio for particles in the 1-150 um range, with lower pH and magnesium dosages leading to more uniform and smaller particles (Shin and Lee, 1997). Another study found that the electrical surface charge (zeta potential) of the struvite particles grown varies with the solution pH and magnesium concentration (Bouropoulos and Koutsoukos, 2000). The particles were found to have lower zeta potentials at lower pH (< 9.2) and reach an isoelectric point at an M g concentration of approximately 10" molar. This indicates that crystal agglomeration could be encouraged at lower pH and higher Mg dosing rates. Hirasawa et al. (1997), found that the shape of the struvite crystals changed from orthorhombic to agglomerated rosettes to needle-like when the Mg:P molar ratio in solution was changed from 1:1 to 2:1 to 4:1. Fine crystals were also observed to be forming in the 4:1 Mg:P molar ratio sample. This makes it unclear whether the change in crystal morphology is due to changes in the molar ratios or in the initial supersaturation of the solution. The settling characteristics and chemical composition of struvite containing precipitates have been found to change based on the order in which Mg, N , and P containing reagents are added to a solution, as well as the pH at which the reaction takes place, and the changes in pH of the solution during the precipitation reaction (Dempsey, 1997) 7 B A C K G R O U N D Individual struvite crystals have been described as having an orthorhombic (Doyle et al., 2000), hexagonal/rectangular (Munch and Barr, 2001), coffin lid or arrow-head (Wierzbicki et al.,\991) shape, depending on the conditions in which they are grown and the presence of inhibiting compounds. Other studies conducting pilot or full-scale fluidized bed crystallization of struvite from anaerobic digester liquors have reported widely varying crystal size distributions. Battistoni et al. (2001) report that 0.35mm crystals containing struvite, hydroxyapatite and calcium carbonate are grown on 0.26 mm sand grain seed material. Crystals of sizes ranging from 0-3 mm consisting of nearly pure struvite were grown in studies spanning up to 2 months in a pilot-scale struvite recovery operation in Fukuoka City, Japan (Abe, 1995). Nearly pure struvite crystals, with diameters ranging from 0.5-lmm, were produced in a full-scale struvite recovery operation in the Shimane Prefecture, Japan (Ueno and Fujii, 2001). Using a similar process as that used by Ueno and Fujii at pilot scale, 0.11 mm crystals consisting of greater than 90% struvite were grown in Brisbane, Australia (Munch and Barr, 2001). The growth rate of the crystal diameter reported by Abe (1995) ranged from 0.061-0.173 mm per day and their data shows that a steady state crystal size was not reached during their studies. Takiyama et al. (1997) suggest that the lag time between startup and reaching the steady-state crystal size distribution can be shortened (from approximately 7 to 2 crystal residence times) by seeding the reactor with product from a reactor operating at steady-state. This indicates that using product from another installation to seed the reactor could significantly shorten the startup time. 3.3. Struvite Formation Models Several models have been developed and used to predict the possibility and rate of formation of struvite in sludge digestion equipment, as well as in dedicated struvite crystallizers. These range from simple empirical and equilibrium chemistry models to complex 3 phase, dynamic physical-chemical models. Battistoni et al. (1998) have developed a double saturation model, based on pH and contact time, to describe the operation of a sand-seeded, fluidized bed crystallizing reactor recovering a mixed crystal of struvite, hydroxyapatite and calcium carbonate. This model was 8 B A C K G R O U N D further refined to describe the operation of a long term pilot study (Battistoni et al., 2002). Unfortunately this model does not take the entire equilibrium chemistry into account and relates supersaturation only to pH. This makes direct application of this model to other reactors and other wastewaters unlikely, since the composition of anaerobic digestion liquors can be quite variable from site to site. In the United Kingdom, several studies have been performed to determine the potential for struvite formation in various streams at wastewater treatment plants, using the commercially available Struvite version 3.1 model developed by Loewenthal and Morrison of the University of Cape Town, South Africa. These studies have shown that, in general, the highest potential for phosphate recovery as struvite from wastewater treatment plants occurs in the anaerobic sludge handling liquors of treatment plants that do not use chemical phosphorus precipitation (Doyle et al., 2000; Parsons et al, 2001; Jaffer et al, 2002). Generally the Struvite 3.1 model was found to under-predict struvite formation at high pH values, indicating that further calibration of the model may be needed for accurate prediction of struvite formation in each particular wastewater. Ohlinger (1998) has used a P s equilibrium curve to predict the struvite formation from supernatants from the Sacramento Regional Wastewater Treatment Plant with good success. This model is simply based on the equilibration of a sample through the formation of struvite crystals. This model wil l also likely require calibration for each wastewater treated, since it is not based on a thermodynamic equilibrium. A three phase dynamic model has been developed by Wentzel et al. (2001) to predict the behavior of a solution in which carbon dioxide is being stripped by aeration to increase the pH while struvite and/or calcium phosphates are being formed. This model seems to have great potential to be generally applicable to phosphorus recovery reactors, where pH adjustment is accomplished with air stripping; however, this model also requires calibration in order to be successfully applied to each different solution matrix. Overall, it appears that the chemistry of struvite crystallization is not sufficiently well understood to create a model that would be widely applicable to a variety of solutions without parameter calibration. Models have been developed that accurately describe the crystallization of struvite from anaerobic digester liquors, given that they are calibrated to that particular liquor. 9 B A C K G R O U N D 3.4. Operating Problems at Wastewater Treatment Plants One of the main reasons for the research being conducted on phosphate recovery is the increasing occurrence of operational problems related to phosphorus removal in treatment plants. The three main problems being addressed in the literature are the re-release of excess biologically removed phosphate during anaerobic digestion, the encrustation or scaling of process piping and equipment in anaerobic sludge handling facilities treating B N R sludges, and the production of excess sludge volumes due to chemical and biological phosphorus removal. 3.4.1. Phosphorus Release During Anaerobic Digestion Recent discoveries have shown that a very large part of the phosphorus removed in BNR plants is re-released under anaerobic conditions in sludge digestion systems, and that this release can often lead to supersaturation conditions with respect to struvite in the sludge treatment process (Jardin and Popel, 1994; Niedbala, 1995; Mavinic et al. 1998; Ohlinger et al.,1998). This research has also shown that, in order to maintain very low effluent phosphate concentrations, these B N R plants need to find a way to isolate, and remove the excess phosphate accumulated by the biomass. In a pilot study conducted on site at the City of Penticton A W W T P , it was found that about 80% of the phosphorus removed in the B N R process would be re-released to the digester supernatant and returned to the headworks of the plant, should the phosphate rich secondary sludge be digested anaerobically with the primary sludge (Niedbala, 1995). This study suggested that ferric chloride be used to precipitate the phosphorus from the digester supernatant, to eliminate the possibility of excessive phosphorus loads re-entering the B N R system. Jardin and Popel (2001) have found that, in some cases, much of the phosphorus released in anaerobic digestion is rapidly re-precipitated in the digester, as either struvite or aluminum phosphates, thus preventing excessive feedback of phosphorus to the headworks of the treatment plant. This only occurs i f sufficient quantities of magnesium, aluminum or presumably iron, are present to carry out the precipitation. If these metals are absent or i f phosphorus content of the supernatant is in excess of these metal ions, significant phosphorus feedback to the headworks is probable. 10 B A C K G R O U N D In many cases, and as is current practice in Penticton, the waste activated sludge is dewatered and transported off-site without digestion. In this case, the sludge can be landfilled directly or composted and used as a soil conditioner. Another option is to use chemical phosphorus precipitation with alum or ferric chloride on the digester supernatant return, i f the sludge is digested on site, such as in the Phostrip process. The main problem with this technique is that it can be expensive and creates a relatively large volume of chemical sludge containing either aluminum or iron bound phosphates. These metal phosphate complexes can only be used in a very limited number of phosphorus processing plants in the phosphate industry. These metal bound phosphates are usually landfilled at a significant cost, since it is rarely economically feasible to recover the nutrient value from this type of sludge (Booker et al, 1999; Jeanmaire, 2001). A l l these methods of phosphorus removal are designed to eliminate the excess load of phosphorus to the liquid treatment train of a B N R treatment plant, in order to allow the treatment plant to successfully meet stringent effluent guidelines for phosphorus. Since phosphate is a conservative substance within wastewater treatment systems (i.e. phosphorus does not exist in a volatile or gaseous phase), all of the phosphorus in the wastewater must exit either in the effluent or in the sludge, unless phosphorus accumulates in deposits within the treatment plant or a deliberate attempt is made to recover the phosphorus in a separate process. 3.4.2. Struvite Encrustation High concentrations of ammonia and phosphate have led to increasing operational problems with struvite encrustation of the sludge, supernatant, centrate, and filtrate conveyance systems in the sludge handling systems of wastewater treatment plants. These problems are especially evident in areas of high turbulence, such as pump impellers and pipe bends (Jaffer et al., 2002; Ohlinger et al., 1999). Struvite encrustation problems were first noticed at the Hyperion wastewater treatment plant in Los Angeles in the 1960's (Borgerding, 1972). Since then, the increased use of biological phosphorus removal technologies has led to an increased prevalence of these encrustation problems because these systems lead to higher soluble ammonia, phosphate and magnesium concentrations in the sludge treatment train. In some cases, the conditions for struvite formation are so favorable that piping systems become completely 11 B A C K G R O U N D plugged with struvite within the first year of operation, such as those at the Slough WWTP in England (Williams, 1999). This results in costly and time-consuming maintenance programs in order to prevent failure of the sludge treatment processes. Prevention of these struvite deposition and encrustation problems has been one of the leading driving forces behind phosphorus recovery research, since the removal of phosphorus in the form of struvite in a controlled reactor should drastically reduce or eliminate the encrustation problem in undesirable locations. This would potentially eliminate the cost of the maintenance programs, while producing a valuable by-product. 3.4.3. Excess Sludge Production for P Removal Both chemical and biological phosphorus removal have the effect of increasing the sludge production of wastewater treatment plants. Paul et al. (2001) estimate that the average increase in sludge production from biological and chemical phosphorus removal in France is 3 kg of solids per kg of phosphorus removed, or 5 percent of the total sludge production. The increase in sludge production was also found to be dependent on the BOD:P ratio in the wastewater being treated. It was also estimated that this excess sludge production costs 15 million Euros per year in France. Woods et al. (1999) estimate that sludge volumes can be reduced by up to 49% by implementing phosphorus recovery, depending on the current sludge handling operations at wastewater treatment plants. Another study conducted by Jeanmaire and Evans (2001) concluded that a decrease in sludge mass of 2-8% could be expected i f phosphorus recovery was undertaken at an operating B N R facility with anaerobic sludge digestion. In a case where the secondary sludge is not being digested on site in order to avoid phosphorus feedback and struvite encrustation, significantly larger sludge volume reduction could be expected since approximately 30 to 40% of total solids are destroyed during anaerobic digestion (Metcalf and Eddy Inc., 1991). According to Niedbala (1995), 80% of the sludge produced at the Penticton AWWTP is secondary, and therefore digestion of this sludge would lead to an approximate reduction of 24 to 32 % in total sludge mass being trucked off site. 12 B A C K G R O U N D 3.5. Feasibility of Struvite Recovery from Wastewater Since wastewater treatment plants are often large centralized sources of nutrient discharges to the environment, they have been identified as one of the most promising sources for recovery of phosphorus (Yu, 2001; Woods et al., 1999). The fact that B N R technologies have become more widely used for municipal wastewater treatment over the last two decades has lead to an acceleration of this field of research, since the recovery of phosphorus is more technologically and economically feasible when combined with BNR. Momberg and Oellermann (1992) found that phosphorus recovery, as either struvite or hydroxyapatite from various wastewater streams, appears to be a feasible route for nutrient removal, either as a tertiary treatment or as a side stream process in a B N R plant. This led to further research by several other authors on the ideal placement of a nutrient recovery facility in wastewater treatment plants. Driver et al. (1999) found that up to 80 percent of the phosphate in sewage in the U K could be recycled via precipitation as hydroxyapatite for reuse in the phosphate industry, or for direct reuse as a fertilizer. They also find that animal wastes should be considered as an important source of recoverable phosphorus. Woods et al. (1999) found that phosphorus recovery would be most feasible in treatment plants with high phosphate loads relative to BOD, and high sludge handling costs since they see sludge volume reduction as being a major driving force behind phosphate recovery in the wastewater industry. Social and legislative pressures are also seen as an incentive for implementing phosphate recovery (Jeanmaire and Evans, 2001). Several authors have found that the use of biological phosphorus removal in wastewater treatment makes the recovery of phosphate as struvite more feasible by providing a concentrated phosphate stream in the sludge digestion and dewatering liquors. This allows phosphate recovery to be carried out at minimal cost, while providing other operational benefits such as reduced struvite encrustation, reduced sludge volumes and reduced phosphate feedback through digester supematants (Stratful et al, 1999; Williams, 1999; Edge, 1999; Booker et al. 1999; Jeanmaire and Evans, 2001; Munch and Barr, 2001; Paul et al, 2001). However, it has been found that the recovery of phosphorus is economically and technically non-feasible when chemical 13 B A C K G R O U N D precipitation with aluminum or iron salts is used (Parsons et al, 2001; Paul et al, 2001). Sludge from chemical precipitation processes has also been found to provide little phosphorus value when spread on agricultural land (Edge, 1999). Other waste streams such as piggery waste, abattoir wastewater and other manures have been found to show great potential for future phosphate recovery (Momberg and Oellermann, 1992; Webb and Ho, 1999) Livestock waste streams in British Columbia have been found to account for more than 80% of recoverable phosphorus, with municipal sewage accounting for the remainder (Yu, 2001). Several potential markets have been suggested for use of the recovered phosphorus. These include a sustainable source of high grade material for phosphate industry (Jeanmaire and Evans, 2001), although this would require high retrofit cost for the phosphate processing industry i f the phosphorus is recovered as struvite (Durrant et al, 1999). The more likely market for struvite would be direct use as a slow release fertilizer (Booker et al., 1999). In the U K , struvite was found to be a potential replacement for di-ammonium phosphate fertilizers, especially i f local fertilizer needs in the area of the recovery operation could be met (Gaterell et al, 2000). In Japan, struvite is already being successfully marketed as a premium slow-release fertilizer additive for rice paddy and household use (Ueno and Fujii, 2001). Since nutrient discharges from wastewater treatment plants are increasingly being seen as an important contributor to the degradation of water quality, regulatory agencies are imposing more and more stringent effluent criteria for both nitrogen and phosphorus. These criteria have lead to the widespread use of nutrient removal techniques in the wastewater treatment industry, but it is not until recently that the possibility of recovering these nutrients for subsequent reuse in the fertilizer or phosphate industries has been investigated. Essentially, the recovery of phosphorus from wastewater will provide some closure to the mass balance on phosphorus, while allowing for low effluent concentrations and eliminating the need to dispose of this resource in a non-sustainable manner. 14 B A C K G R O U N D 3.6. Pilot and Full-scale Struvite Recovery Studies Stratful et al. (1999) provide a good overview of various processes that have been studied to recover phosphorus, as either struvite or calcium phosphate. These include the D H V Crystalactor calcium phosphate fluidized bed process, the Rim-Nut ion exchange process, the Unitika Phosnix struvite recovery process, the Kurita fixed bed calcium phosphate process, and the CSIR fluidized bed process. Previous research at U B C has led to the development of a novel reactor design used to recover phosphate from real and synthetic supematants at the bench scale. The bench scale equipment was found to be prone to plugging problems and low recoveries of phosphorus. These problems were largely rectified with the scale-up to pilot scale. The pilot-scale reactors allowed for higher phosphate recoveries (up to 90%) from a synthetic supernatant similar to that expected at the Penticton AWWTP (Dastur, 2001). Since the chemical costs of struvite formation have been found to be a major contributor to the total costs of the process, several researchers have attempted to develop processes whereby no chemicals are used (Battistoni, et al, 1997; Battistoni, et al, 1998; Kumashiro et al, 2001). Battistoni et al. (1997 and 1998) de-gassed carbon dioxide from digester supernatant by air stripping, in order to increase the solution pH to ranges where struvite and calcium phosphates are less soluble; they used the magnesium and calcium present in the wastewater as cation sources for the crystallization of phosphate materials. This approach is feasible in the case of the wastewater treatment plants in these investigations, but would be less feasible in regions with softer waters containing less magnesium and calcium. Another drawback of this technique is that the product is relatively impure, containing a combination of struvite, calcium phosphate, and calcium carbonate. Kumashiro et al. (2001) used sea water as a source of magnesium and produced essentially pure struvite crystals, at operating costs of $0.70 per kg of struvite produced. Ammonia is often present in significantly higher molar concentrations than phosphate in digester supematants. For this reason, several authors have investigated the possibility of recovering both ammonia and phosphate from supematants as struvite. In two studies, 15 B A C K G R O U N D magnesium and phosphoric acid are added to digester supernatant in dosages sufficient to remove 85 to 90 % of the ammonia (Siegrist et al, 1992; Celen and Turker, 2001). The costs for this process ranged from $12 to $20 per kg of ammonia removed. Shin and Lee (1997) found that the addition of sea water and bittern both worked well as magnesium sources for the precipitation of struvite, in order to remove ammonia and phosphorus from a synthetic wastewater. Japan has been the global leader in the recovery of phosphorus as struvite. Several full-scale installations are already in operation. Abe (1995) reports that over 80% phosphorus recovery was possible, when treating supernatant from the Seibu treatment plant in Fukuoka City. This study also found that the struvite could be recovered as grains of diameters exceeding 2 mm. In order to accomplish this, the pH was adjusted by a combination of air stripping of C O 2 and addition of sodium hydroxide, and magnesium chloride was added to ensure that phosphate was the limiting reagent in the formation of struvite. It was found that in order to grow large crystals, re-circulation of the reactor effluent was required when treating supernatants with high concentrations of phosphate. A study conducted by Munch and Barr (2001) in Brisbane, Australia found that struvite crystals with an average diameter of 0.11 mm were grown in a similar reactor where magnesium hydroxide was used for both magnesium dosage and pH adjustment, and no effluent re-circulation was used. Ueno and Fujii (2001) presented results from the full-scale operation of three struvite recovery reactors treating B N R sludge dewatering filtrate at the Shimane Prefecture Lake Shinji East Clean Center. These reactors use a magnesium hydroxide solution for magnesium dosing and some pH adjustment, with the remainder of the pH adjustment being carried out by air stripping of C O 2 and addition of sodium hydroxide. In this reactor, the air blower also acts as an air lift pump, to re-circulate the reactor contents in order to dilute the feed in a double-jacketed column design. A ten day crystal retention time is sufficient to grow crystals of 0.5 to 1 mm in this reactor. This facility produces between 500 and 550 kg of struvite per day and sells the product for $340 per metric ton to a fertilizer company, which also pays for the shipping costs. The fertilizer company blends the struvite with other components to produce an enhanced fertilizer that is claimed to improve the flavour of paddy rice. 16 B A C K G R O U N D Several phosphorus recovery reactor designs, process configurations, and treatment objectives have been successfully tested around the world over the past decade. The optimal configuration appears to be dependent on the characteristics of the waste stream to be treated, the local cost of chemicals, and the potential market for the product. In general, it appears that significant cost reductions can be achieved by reducing the chemical usage at these plants by using air stripping for pH adjustment and using sea water or other inexpensive magnesium sources for dosing magnesium to the reactor. It also appears that in order to grow large (>1 mm) struvite crystals, recirculation of the reactor effluent is often necessary to dilute the waste stream being treated, and that long crystal retention times are required (> 10 days). Overall, the fluidized bed crystallizer, without heterogeneous carrier material, seems to be the most widely used and successful design for these reactors. 17 M A T E R I A L S A N D M E T H O D S 4. MATERIALS AND METHODS Based on previous experiments at the bench scale, a pilot scale reactor was designed and tested at the U B C Environmental Engineering Pilot Plant using a synthetic feed. Two identical reactors based on this design were operated in parallel over a four month period, from September to December of 2001, at the City of Penticton AWWTP, and were housed in a heated chemical storage building on site as shown in Figure 4.1. Figure 4.1: Pilot-scale reactor setup at the City of Penticton A W W T P . Left: two parallel fluidized bed reactors; top right: magnesium chloride, sodium hydroxide (in foreground) and supernatant storage tanks (in background); bottom right: close-up of one reactor control box, with feed, recycle and magnesium dosing pumps and pH controller. 18 M A T E R I A L S A N D M E T H O D S During the test period at the U B C Pilot Plant, the analytical techniques to be used in this study were developed and evaluated. In most cases, the methods developed for use with the synthetic feed proved to be successful with the real supernatant; however, some changes were necessary. 4.1. Reactor Design The reactor used in this study was based on a 3X linear scale up of the bench scale reactor, designed by the U B C phosphate recovery team (Dastur, 2001). Figure 4.2 shows the basic design of the reactor and associated equipment. The reactor itself was a fluidized bed reactor with sections of increasing diameter and a settling zone at the top. The diameter changes caused turbulent eddies above each transition, ensuring that sufficient mixing existed in the reactor and also helped to classify the fluidized particles by size; as such, only the largest crystals in the reactor were harvested. The crystallizer was constructed of clear P V C piping connected with standard Schedule 40 or Schedule 80 P V C fittings. An attempt was made to keep the inside joints between piping and fittings as smooth as possible, to minimize dead zones where the fluidized particles could settle and struvite encrustation problems could occur. Clear piping was used in order to be able to monitor the behavior of the struvite crystals in the fluidized bed, and monitor for signs of plugging or encrustation. The clear piping also made it easier to monitor the expanded and collapsed bed heights of the struvite crystals. For the pilot scale reactor used in this work, the inside diameters were 40 mm, 52 mm and 77 mm for the bottom, middle and top sections of the fluidized zone. The clarifier section at the top of the crystallizer was built out of 202 mm diameter clear acrylic pipe. The total liquid volume of each reactor was approximately 19 liters, 9 liters of which were in the three fluidized zones. 19 M A T E R I A L S A N D M E T H O D S M A P Crystal l izer MgCI 1 m 3 N a O H 1 m 3 pH Control Probe 40 mm ID Harvest Sect ion Injection Port ? 202 mm i d 77 mm ID 52 mm ID Recyc le 1 External Clarifier Effluent Sludge Supernatant Storage 2 X 1 6 m 3 Figure 4.2: Pilot-scale struvite crystallizer reactor process design. Each reactor was initially seeded with one liter of struvite crystals grown from synthetic supernatant at the U B C pilot plant. This was done in order to avoid problems encountered previously when trying to self seed the reactor at a high supersaturation ratio. The reactor does not use any carrier material such as sand for seeding, and therefore the product from the reactor is nearly pure struvite. The total height of the reactors used in this study was approximately 4900 mm. The total liquid flow rates through each reactor for the duration of the study was 3.6 liters per minute. Each reactor was equipped with two pH probes, one in the top of the harvest zone and another in the external clarifier. The pH probe in the harvest zone was used for feedback control using a proportional flow pH controller. Magnesium was dosed to the reactor in the form of magnesium chloride solution to supply the desired magnesium to phosphorus molar ratio in the reactor. 20 M A T E R I A L S A N D M E T H O D S 4.1.1. Injection Port Design The reactor injection port was designed to blend the supernatant feed stream with the recycle stream from the external clarifier, the magnesium chloride solution from the dosing pump and the sodium hydroxide solution from the pH controller. Figure 4.3 shows a simplified cross section of the injection port design. The injection port block itself was constructed out of stainless steel, as were the magnesium and caustic injection ports. These parts of the reactor were built out of stainless steel, in order to prevent corrosion and to withstand regular scouring from cleaning. Mixed Reactor Influent to 40 mm Sect ion 2.4 mm ID Injectors MgCI F e e d From Peristalt ic Pump Clarif ied Recyc le From Progress ive Cavi ty P u m p High Turbulence Zone N a O H F e e d From pH Control ler D iaphragm P u m p Sett led Supernatant From Progress ive Cavi ty P u m p 1 Figure 4.3: Pilot-scale struvite crystallizer injection port assembly. The injection port assembly was easily disconnected from the reactor by means of quick release connectors, in order to be able to clean this section regularly. Since the magnesium chloride and sodium hydroxide (caustic) injection points are coincident, high local supersaturation ratios exist in this zone and some encrustation of the chemical feed ports occurred during the course of the experiment. The magnesium and caustic injection ports were 21 M A T E R I A L S A N D M E T H O D S cleaned with a welding rod (approximate diameter 1.6 mm) every time the reactor was stopped for harvesting, or whenever decreased flow was observed. The injection ports were machined from stainless steel rods to have LA inch NPT threading on both ends, to connect to the injection port block and to quick release tubing connectors, and were bored out to 2.4 mm as shown in Figure 4.3. There was some encrustation of the high turbulence area indicated in Figure 4.3 throughout the experiment, but complete blockage never occurred and cleaning was only performed every 2 to 7 days. The high turbulence area was cleaned using a length of threaded rod of similar diameter to the gap between the magnesium and caustic injection ports (approximately 10 mm). No struvite scaling was observed below the magnesium and caustic injection points, indicating that the solution remained undersaturated until it passed through the high turbulence area where struvite formation was initiated. 4.1.2. Harvest Zone Design The harvest zone, located immediately above the injection port, had an internal diameter of 40 mm, held a volume of 1.1 liters and was 960 mm in length. Two ball valves (one at the top and one at the bottom as shown in Figure 4.2) were used to isolate the harvest zone when injection port cleaning or struvite harvesting was required. The harvesting procedure is described in Section 4.1.9 below. The empty reactor fluid upflow velocity in the harvest section was 2810 mm per minute and the Reynolds number for this condition was estimated at 2100. It is important to note that the fluid upflow velocities and Reynolds numbers during fluidized bed operation with a fully loaded reactor (i.e. 6-8 liters collapsed bed struvite crystal volume) will be quite different from these values. 4.1.3. Reaction Zone Design Immediately above the harvest zone were two expanding sections with 52 and 77 mm inside diameters, and volumes of 3.6 liters and 4.3 liters respectively. The 52 mm inside diameter section had a length of 1770 mm and was equipped with an isolation ball valve at the top in order to be able to separately drain each section. The 77 mm inside diameter section was 940 mm in length and was mounted to the clarifier section above using a bulkhead fitting. 22 MATERIALS AND METHODS Empty reactor upflow velocities were 1690 mm per minute and 770 mm per minute for the 52 and 77 mm inside diameter sections respectively, which corresponds to Reynolds numbers of 1600 and 1100. Again the hydraulics of the reactor were significantly different from this when the reactor was fully loaded with struvite crystals and behaving as a fluidized bed reactor. The reactor diameter changes were accomplished using standard P V C expansion couplings with rounded transitions. During the operation of the reactors, the fluidized bed of struvite crystals expanded to the top of the reaction zone and settled in the bottom of clarifier section mounted above. This causes the full 9 liters of reactor volume to be used for crystal growth, allowing maximal contact between the supersaturated solution and the struvite crystals. 4.1.4. Clarifier Zone Design Mounted to the top of the reaction zone was a 202 mm inside diameter clarifier section with a height of approximately 380 mm and two side outlets for the overflow from the reactor. The main overflow was set at approximately 300 mm water depth in the clarifier section, while the backup overflow was set at approximately 350 mm water depth. The main overflow was connected to the external clarifier (see Figure 4.2) by a vertical 25 mm inside diameter clear P V C pipe tipped with a length of 31 mm inside diameter flexible tubing. The flexible tubing was placed in the external clarifier in a U shape with the submerged exit in the upwards vertical position on the external clarifier wall opposite the recycle and effluent ports. The backup overflow was connected to the external clarifier by 12.7 mm outside diameter LDPE tubing (9.7 mm inside diameter) which was mounted to the top edge of the external clarifier with a horizontal exit above the water surface. Both overflows were equipped with siphon breakers, since they had a tendency to become vapour locked, causing the system to overflow. The clarifier section was flat bottomed and equipped with a drain valve to remove accumulation of suspended solids. In practice, this valve was never used since the only accumulation observed was of small struvite crystals which settled and formed a cone shape in the bottom of the clarifier section with a side slope of approximately 60°. The normal operating 23 M A T E R I A L S A N D M E T H O D S volume of the clarifier section was approximately 10 liters and the upflow velocity at design flow was 110 mm per minute. At this velocity, very few struvite crystals were observed to be escaping the reactor. 4.1.5. External Clarifier and Recycle Flow Each reactor was equipped with an external clarifier to act as an effluent storage vessel for recycling to the injection port and to ensure that any remaining fine-suspended solids were not returned to the reactor. The external clarifiers were rectangular with surface dimensions of 365 mm by 400 mm and had a square pyramidal bottom, with a 45° slope. The external clarifiers were placed on the floor adjacent to each reactor as shown in Figure 4.4. The water level in the external clarifiers was maintained at a side water depth of approximately 305 mm, with a freeboard of 50 mm. The approximate external clarifier volume was 54 liters. Each external clarifier had a surface area of 0.15 square meters which resulted in a surface overflow rate of between 2.7 and 8.2 mm per minute depending on the supernatant feed flow rate. This overflow velocity was independent of the recycle flow rate, since the recycle was withdrawn as an underflow from the external clarifier. It is important to note that hydraulic conditions in the external clarifiers were far from ideal; there was no inlet zone to dissipate the momentum generated by the 4500 mm fall to the clarifier from the top of the crystallizer, other than a bend in the tubing. Also, both exits from the clarifier were sharp orifices and were not equipped with any weirs or manifolds to distribute the flow. The clarifiers did however produce a relatively clear overflow stream and accumulated some sludge in the bottom, indicating that some solids did escape the clarifier section at the top of the crystallizers. 24 M A T E R I A L S A N D M E T H O D S 1: Reactor A 2: Reactor B 3: Reactor A 4: Reactor B 5: Reactor A 6: Reactor B 7: Reactor A 8: Reactor B Feed P u m p Feed P u m p Crystallizer Crystallizer External Clarifier External Clarifier Recycle P u m p Recycle P u m p Figure 4.4: Pilot-scale schematic. The recycle flow back to the fluidized bed reactor was withdrawn from a port on the side of the external clarifier approximately 150 mm below the water surface. The recycle was pumped using a Moyno Model 500 332 progressive cavity pump with a Vi HP motor and variable frequency drive to allow precise flow control (capacity 0.8-18.9 L/min). The set point for the flow rate of the recycle to each reactor was varied between 2.4 and 3.2 liters per minute during the course of the experiment and verified daily. The treated effluent from the external clarifier overflowed by gravity from a port near the top of the external clarifier to a floor drain which flowed back to the wastewater treatment plant headworks.. The effluent drain line was equipped with a 3 way valve to allow for collection of effluent samples and flow measurement. A sludge drain valve was placed on the external clarifier bottom in order to collect and remove any accumulated sludge from the clarifier. A small quantity of this sludge was wasted approximately weekly and consisted of a blend of small struvite crystals and suspended solids from the digester supernatant. 25 M A T E R I A L S A N D M E T H O D S The total reactor flow rate was measured from in the 25 mm overflow pipe into the external clarifier using a graduated cylinder and stopwatch. A l l of the pumped and gravity flow tubing exiting the external clarifier, as shown in Figure 4.4, was 12.7 mm outside diameter LDPE tubing (9.7 mm inside diameter). Some encrustation of this tubing was noticed during the course of the study, but it was found that it could be easily removed by periodically flexing the tubing and complete blockage of these lines was never observed during this study. The fact that some encrustation did occur here indicates that the reaction taking place in the crystallizer was not 100% complete. 4.1.6. Supernatant Storage Tanks and Supernatant Feed Flow The digester at the City of Penticton AWWTP is a two stage anaerobic digester, operated in the mesophilic temperature range. The first stage of the digester is gas mixed and the second stage is unmixed. Supernatant from the second stage of the digester was pumped from an overflow splitter box to two storage tanks for use in the pilot struvite crystallizer. The supernatant from the splitter box normally flowed by gravity back to the headworks of the treatment plant, but by plugging the exit and using a submersible pump, it was possible to intercept the needed amount of supernatant and fill one of the storage tanks within a few hours. The two storage tanks each had a capacity of 16,000 liters and were equipped with overflows and drain valves. The supernatant to be used in the reactors was pumped out of the tanks from a fitting located approximately 500 mm above the tank bottom. This was done to allow any suspended solids in the supernatant to settle to the bottom of the tank and prevent excess suspended solids from entering the reactor. One full tank would typically last approximately seven days when feeding both reactors. It was therefore possible to fill each tank several days before it was needed, in order to allow settling time before withdrawing any supernatant. This was important since the supernatant collected occasionally contained high levels of suspended solids (over 2000 mg/L) when attempts were being made to increase the loading of secondary sludge to the digesters. The residual sludge remaining in each tank was drained and returned to the treatment plant's headworks when the tank level approached the feed outlet. In this way, the settled solids were regularly removed from the tanks and no accumulation was observed. 26 M A T E R I A L S A N D M E T H O D S The large volume of the storage tanks also allowed a constant feed strength to be maintained for several days at a time when the digester's operation was being drastically changed to increase the supernatant phosphate concentration. This was crucial during the initial months of the study, when the supernatant characteristics were changing significantly on a daily basis, in order to maintain relatively constant conditions within the crystallizers. The piping from the feed tanks to the reactors was arranged so that both reactors were fed from the same line and so that supernatant could be drawn from either feed tank individually or both in parallel, as shown in Figure 4.4. During the course of the experiment, feed was always drawn from a single tank, while the other tank was being drained, refilled and allowed to settle. Feed supernatant was pumped from the storage tanks using Moyno Model 500 331 progressive cavity pump with a Vi HP motor and variable frequency drive to allow precise flow control (capacity 0.3-7.6 L/min). Each reactor had its own independent pumping system, in order to ensure accurate flow control and to allow different types of operation to be evaluated in parallel. The set point for the flow rate of the feed to each reactor was varied between 0.4 and 1.2 liters per minute during the course of the experiment. 4.1.7. pH Control and Caustic Soda Dosing Since the solubility of struvite is highly pH dependent, a pH control system is critical in maintaining the desired supersaturation conditions within the crystallizers. For this study, the pH within the reactors was adjusted using a sodium hydroxide (caustic soda) solution. The sodium hydroxide solution was made up on-site from industrial grade sodium hydroxide pellets delivered in 22.7 kg bags (PrairieChem Inc.). The solution was made up and stored in standard one cubic meter bulk liquid storage tanks, as shown in Figure 4.1. Since there were no means to block air access to the sodium hydroxide solution, it became slowly buffered by carbon dioxide from the air. This caused the solution to become less effective in raising the pH in the reactors over time; therefore, an attempt was made to keep a minimal volume of solution on hand in the storage tank. Once this problem was noticed, each batch of caustic solution was made up of 4 kilograms of sodium hydroxide pellets in approximately 500 liters of tap water. Each batch would typically last one week, when made up in this manner. 27 M A T E R I A L S A N D M E T H O D S The sodium hydroxide solution was metered into the reactor through the injection port as described above in Section 4.1.1. The pH in the reactor was monitored at the top of the harvest zone as shown in Figure 4.2, using a Cole Parmer double junction in-line pH probe. The pH in the reactor was controlled based on this signal using a Cole Parmer model 56025-40 pH pump control system with proportional output. This pH control unit allowed pH control to within ±0 .1 pH units and could dose at a maximum rate of 20 liters per hour. In practice, the pH reading at the top of the harvest zone was observed to vary by up to ±1 pH unit due to the lag time between the injection port and the pH probe. A previous design of the reactor had the pH probe located at the bottom of the harvest zone, but this caused severe encrustation problems on and around the pH probe, thus interfering with pH readings. The tubing between the sodium hydroxide solution storage tank and the pH controller, and between the pH controller and the reactor injection port, was 6.3 mm outside diameter LDPE tubing (4.3 mm inside diameter). Using the concentration of sodium hydroxide described above (8 g/L), the metering pump operated at a rate well within it's maximum capacity, and the pH was maintained at or slightly below (-0.2 pH units) the pH controller setpoint in the reactor effluent. Although significant variations in the pH were measured at the top of the harvest zone, the pH in the external clarifier remained constant within 0.1 pH units. This indicates that mixing and equalization between the harvest zone and the external clarifier lead to relatively homogeneous conditions in the effluent. The pH in the external clarifier was monitored using an Oakton continuous pH monitor, equipped with an Oakton gel filled, epoxy body pH probe. The pH probes in the top of the harvest zone (the control probes) were calibrated whenever the reactor was shut down for harvesting, that is, whenever it was possible to remove these probes without losing the reactor contents. They were calibrated using standard pH 7 and pH 10 buffer solutions, as per manufacturer's instructions for two point calibration. The pH probes in the external clarifier (effluent monitoring probes) were calibrated every two to four days using the same method as the control probes. The calibration of the probes was periodically verified by measuring the pH of a solution and ensuring that all four pH meters displayed a pH that was within 0.1 pH units of each other. In general, the control probes responded much faster and maintained their calibration better than the effluent monitoring probes, probably due to their higher quality and industrial design. 28 M A T E R I A L S A N D M E T H O D S 4.1.8. Magnesium Chloride Dosing Since magnesium was the limiting reagent in the formation of struvite from the Penticton digester supernatant, it was necessary to supplement the reactor with magnesium. Throughout this study, the objective was to keep a molar ratio of Mg:PC»4 equal to 1.3:1 within the reactor. This higher magnesium concentration causes the limiting reagent to be phosphate and thus allows for lower effluent phosphate concentrations than in magnesium limited systems. In this study, the magnesium required to establish the excess Mg:PC>4 ratio was provided by using a solution of magnesium chloride hexahydrate. The magnesium chloride used was of commercial grade and was supplied in 50 kg bags (Thunder Sword Resources Inc.). The magnesium chloride solution was stored in a standard one cubic meter bulk liquid storage tank as shown in Figure 4.1. Typically, the solution was made up of four kilograms of magnesium chloride hexahydrate crystals in 1000 liters of tap water; however, this concentration was varied somewhat during the course of the experiment for convenience. The magnesium chloride solution was pumped from the storage tank to the injection port of the reactor using a MasterFlex L/S variable speed peristaltic pump with Standard pump heads. The tubing used in the peristaltic pumps was 6.3 mm outside diameter neoprene tubing. A l l tubing used for conveying the magnesium chloride solution from the storage tank to the pump and from the pump to the reactor was 6.3 mm outside diameter LDPE tubing (4.3 mm inside diameter). Two peristaltic pumps were available in order to have independent control of the magnesium dosing rate in each reactor; however, during the first months of the experiment, both reactors were fed using two pump heads mounted on a single pump, in order to ensure that both reactors were dosed with the same amount of magnesium. The flowrate of the magnesium solution into each reactor was measured by timing the drawdown in a graduated cylinder. Based on this flow measurement and the analysis of the magnesium concentration in the feed tank, it was possible to estimate the magnesium dosage applied to each reactor each day. These flow measurements were verified roughly against the total volume of magnesium solution used each day to ensure that the recorded flow rate was representative. The magnesium solution dosing rate varied between 20 and 60 milliliters per minute over the course of the study. 29 M A T E R I A L S A N D M E T H O D S 4.1.9. Crystal Harvest Procedure Crystals were harvested from the reactor after the feed, recycle and chemical feed flows were stopped and the crystals are allowed to settle. The harvest zone was isolated using ball valves after the settling was complete and the settled bed volume of struvite crystals was measured. In order to remove the crystals for harvesting, the injection port section of the reactor was removed using quick disconnects and the crystals were allowed to fall into a bucket. The harvest zone was then rinsed with reactor effluent to ensure that all crystals were removed. The harvested crystals were then dried and analyzed as described below. Once the harvest was complete, the injector port section was reattached, the isolation valves were opened and the feed, recycle and chemical feed flows were restarted. Occasionally it was necessary to apply compressed air to the top of the harvest zone (through the pH probe port after the probe was removed) in order to force the settled struvite crystals to fall from the reactor. This was necessary because the crystals were often highly irregular in shape and tended to agglomerate and bridge across the 40 mm section. This usually occurred when the crystals were of poorer quality (i.e. smaller size and more brittle). 4.1.10. Crystal Drying and Analysis After the crystals were harvested from the reactor in a bucket, the remaining liquid was decanted off and the struvite crystals were spread over a 300 mm by 750 mm drying rack. The drying racks were made of a wooden frame supporting a standard plastic window screen. The size of the openings in this screen material was not measured. The crystals tended to agglomerate into clumps in the bucket upon decanting of the supernatant. For this reason, little crystal mass was lost through the screen. Once the crystals were spread over the drying rack, it was suspended between two buckets and the crystals were left to dry for 24 hours with a 15 amp ceramic heater fan blowing warm air over them. The dried crystals were then removed from the drying rack and screened using standard sieves with nominal sieve sizes of 2 mm, 1 mm and 0.5 mm. The sieving apparatus was also equipped with a lid and a pan for collecting the portion of crystals with diameters of less than 0.5 mm. In this manner, it was possible to segregate the dried harvested 30 M A T E R I A L S A N D M E T H O D S crystals into four size fractions: 0-0.5 mm, 0.5-1 mm, 1-2 mm and greater than 2 mm. The crystal mass collected in each size fraction from each harvest was measured using an analytical balance, and a sample of each size fraction was collected for further analysis. It should be noted that the harvesting, drying and sieving process caused significant breakage of the crystals removed from the reactor. This was especially evident in the early stages of the experiment when the crystals were very brittle. In the later stages, the crystals became rounder, harder and denser, resulting in less breakage from handling. Even though this breakage was evident, it was assumed that the size distribution after handling was representative of what could be expected should the process be commercialized. In a commercial process, the harvested crystals would need to be screened, dried and bagged by a mechanized process, which would probably have a similar impact on the crystals as the handling procedure used here. 4.1.11. Daily Monitoring and Control Each day, several operating parameters were monitored in order to characterize the operation of each reactor. In each reactor, the effluent flow rate, the total combined flow rate in the down pipe from the crystallizer to the external clarifier, and the flow rate of magnesium chloride solution into the reactor were monitored. The tank levels in both the sodium hydroxide and magnesium chloride storage tanks were recorded daily, and the usage of each solution was calculated from by difference from the previous days reading. The mass of reagent added to the chemical storage tanks, as well as the volume of tap water added, was recorded whenever solutions were replenished. The pH of the digester supernatant in the storage tank being used was measured and recorded daily as well as the pH of the effluent from each reactor. Samples of the digester supernatant and the effluent from each reactor were collected daily, and subsequently filtered and analyzed for magnesium, ortho-phosphate and ammonia nitrogen, as described in Section 4.4. After all the other daily readings and samples were taken, the reactors were shut down and the struvite crystals were allowed to settle. Once the settling was complete, the collapsed bed volume of crystals was recorded. After all the required data was collected, crystals were 31 MATERIALS AND METHODS harvested as described in Section 4.1.9 and any required reactor maintenance, such as injector port cleaning and pH probe calibration, was performed. Once this maintenance was completed, the reactors were restarted and the flows were readjusted to match the desired set points. 4.2. Struvite Solubility Determination For the purpose of the operation of the pilot struvite crystallization reactors at the City of Penticton AWWTP, a Ps curve developed at the University of British Columbia for bench scale crystallizer testing was used. This solubility curve was developed by melting struvite crystals in distilled water and analyzing the resulting solution at equilibrium for pH, dissolved magnesium, ammonia and ortho-phosphate (Dastur, 2001). From the experimental data collected in Penticton, it became apparent that the equilibrium Ps was significantly different in digester supernatant than in distilled water, and therefore a new solubility curve was developed for digester supernatant after the pilot scale trials in Penticton. 4.2.1. Apparatus The apparatus used for determining the solubility of struvite was a six station paddle stirrer (Phipps and Bird). Square jars containing 1.5 liters of the solution being tested were immersed in a constant temperature bath at 20 ± 0.1 °C. The paddle stirrers were set to operate at 70 ± 2 R P M . A sufficient mass of struvite crystals, harvested from the reactors in Penticton, were placed in each jar to ensure that some solid phase struvite remained at equilibrium. Equilibrium was assumed to be reached 24 hours after conditions were changed in each jar, based on previous research at U B C (Ping Liao, Research Associate, U B C Department of Chemical Engineering, pers. comm.). The pH in each jar was adjusted using dilute hydrochloric acid and sodium hydroxide solutions, in order to determine the solubility of struvite over the expected operating range of struvite crystallization equipment (i.e. between pH values of 7 and 9). In a previous study, these conditions were found to be optimal to approximate equilibrium conditions while minimizing the volatilization of ammonia during the test (Ping Liao, pers. comm.). 3 2 M A T E R I A L S A N D M E T H O D S Two sets of tests were conducted, one using distilled water and one using digester supernatant from the City of Penticton AWWTP. For each test, each beaker was filled with 1.5 liters of either distilled water or supernatant, then struvite crystals were added to the reactor and mixed in. For the tests using supernatant, a reagent grade magnesium chloride solution was dosed into the supernatant to result in an initial molar Mg:P ratio of 1.3:1 as used in the pilot-scale experiment. The pH of each jar was then adjusted as desired and the apparatus was left to equilibrate for 24 hours. At the end of the 24 hour period, the pH and conductivity in each jar were measured and samples of the equilibrated solution were filtered and analyzed for magnesium, calcium, ammonia and ortho-phosphate. 4.3. Crystal Product Analysis In order to determine the composition and purity of the crystals grown from the supernatant in the pilot scale crystallizers at the City of Penticton A W W T P , samples of several of the harvested crystals were dissolved in a 0.5% nitric acid solution. These solutions were subsequently analyzed for the components of struvite, as well as calcium, aluminum, iron and potassium. For each sample analyzed, approximately 0.03 g of crystals was dissolved in 50 ml of 0.5% nitric acid solution. In order to accelerate the crystal dissolution, the samples were submerged in an ultrasonic bath until no visible solids remained. The samples were then allowed to sit for 24 hours before being analyzed, in order to ensure that any invisible crystallites had time to dissolve and the solution had time to mix completely. Each sample was vortex mixed and inverted several times during this time to further accelerate the mixing. Trace amounts of solid residue were fount at the bottom of some of the samples at the end of 24 hours. This was found to be fibrous material, possibly originating from the struvite crystals themselves, or from dust contamination either in the laboratory or in the crystal handling and drying process at the wastewater treatment plant. No attempt was made to quantify the mass of this fibrous residue or to identify it's chemical makeup. It was simply observed under a microscope and identified as being fibrous material. An image of this material is presented in Figure 4.5 33 M A T E R I A L S A N D M E T H O D S /'05-03-2002f Jr. u I Figure 4.5: Fibrous residue from crystal dissolution tests. 4.4. Analytical Methods Two general types of analyses were conducted during the course of this study: field analyses at the wastewater treatment plant and lab analyses performed in the UBC Environmental Engineering lab. The field tests were meant to be representative of analyses that could be performed routinely on-site by wastewater treatment plant staff, while the tests performed at the U B C lab were generally of a non routine nature and were only necessary for research purposes. The exception to this was the analysis for magnesium. Since there was no equipment available in the lab at the wastewater treatment plant to measure magnesium concentrations, samples were shipped from Penticton to the U B C lab for analysis. In the future a method of measuring magnesium on site at the wastewater treatment plant would be advisable to minimize analytical turnaround time and to be able to more accurately control the reactor operating conditions. 4.4.1. Magnesium Magnesium results reported throughout this report were analyzed by atomic absorption. Most samples were analyzed for dissolved magnesium; however, some samples were analyzed for total magnesium, to determine i f a large amount of magnesium was present in particulate form. 34 M A T E R I A L S A N D M E T H O D S A n attempt was made at determining the dissolved magnesium concentration in the digester supernatant matrix using E D T A titrations for total and calcium hardness. The assumption is that the difference between the total hardness and the calcium hardness is composed entirely of magnesium hardness. Unfortunately, this method gave results that were orders of magnitude different from the values determined by atomic absorption, and this technique was abandoned. Magnesium analysis in the U B C lab was performed by flame atomic absorption spectrophotometry, using a Varian Inc. SpectrAA220 Fast Sequential Atomic Absorption Spectrophotometer. Instrument operational parameter details can be found in Appendix A. 4.4.2. Ortho-phosphate Ortho Phosphate was measured on site at the wastewater treatment plant using the Stannous Chloride method as described in method number 4500-P D in Standard Methods for the Examination of Water and Wastewater (APHA, A W W A and WPCF, 1995), with the exception that sample sizes were 50 ml instead of 100ml. The absorbances of the samples were measured using a Milton Roy Spectronic 401 spectrophotometer. Ortho phosphate samples analyzed at the U B C laboratory were analyzed using flow injection analysis on a LaChat QuikChem 8000 instrument configured as described in Appendix A. Flow injection analyses were performed on the samples from the crystal product analysis and struvite solubility determination experiments described in Sections 4.2 and 4.3 above. Initially, on-site ortho-phosphate analysis was attempted using a Hach DR2000 spectrophotometer with the ammonia-molybdovanadate method. Unfortunately, the color of the supernatant interfered with the yellow color developed and measured in this method, and it proved to be unusable. 4.4.3. Ammonia On-site ammonia tests were performed using a Hach DR2000 spectrophotometer using the salicylate method (Hach, Nitrogen, Ammonia, High Range Test'N Tube method 10031). 35 M A T E R I A L S A N D M E T H O D S The relative standard deviation of this method was found to be 3.7%, with replicate analyses varying by as much as 30 mg/L. Ammonia analyses performed at the U B C laboratory used flow injection analysis on the same LaChat instrument as the phosphate analysis described above. Instrument operational parameter details can be found in Appendix A . 4.4.4. pH Field pH measurements were performed using the Oakton continuous pH monitors described above in the reactor design. Laboratory pH measurements were performed using a Beckman 044 pH meter equipped with an Oakton pH probe. A l l pH meters were regularly calibrated by the two point method, using buffer solutions of pH 7 and pH 10. 4.4.5. Calcium, Aluminum and Iron Calcium, aluminum and iron analysis was performed on the samples from the crystal product analysis. This analysis was performed by atomic absorption spectrophotometry using the same instrument as for the magnesium analysis described above. Instrument operational parameter details can be found in Appendix A . 4.4.6. Potassium Potassium analysis was performed on the samples from the crystal product analysis. This analysis was performed by atomic emission spectrophotometry using the same instrument as for the magnesium analysis described above. Instrument operational parameter details can be found in Appendix A. 4.4.7. Total Phosphorus Total phosphorus analysis for the estimation of full-scale phosphorus loads in the wastewater treatment plant were digested using the sulfuric acid-nitric acid digestion method (APHA, 1995, method 4500-P B.4) and analysed by flow injection analysis on the same LaChat instrument as the ortho-phosphate samples as described above. 36 M A T E R I A L S A N D M E T H O D S 4.4.8. Filtration A l l field samples were filtered using Fisher Brand G6 filter papers with a nominal pore size of 1.5 microns to remove suspended solids from the samples. 4.4.9. Conductivity Conductivity was measured using a Hanna Instruments HI9033 multi range conductivity meter for the struvite solubility tests described above. 4.5. Terminology For ease of understanding in the following sections, several of the terms used to describe the operation and control of the struvite crystallizers are defined here. 4.5.1. Struvite Solubility Product The solubility product or K s p as defined in this study is the product of the ionic activities of the precise ionic forms involved in the formation of a precipitate. For the case of struvite, this relation is defined by Equation 1, where the {} brackets indicate ion activity in moles per liter. This involves the speciation of analytically determined concentrations using published acid and base dissociation constants, as well as an adjustment for activity. The result is theoretically a thermodynamic constant applicable under any conditions; however, for this to be true, all potential reactions that could be affecting the speciation of each compound must be accounted for and properly analyzed. This also requires accurate values for dissociation constants and solubility products for all related compounds. A rough attempt has been made here to quantify a K s p value for the struvite crystals formed in the pilot plant in Penticton; however, due to a lack of analytical and experimental information, this value is not used to quantify the operation of the reactor. Ksp={Mg2+}{NH4+}{P043-} E q A The ionic strength of the solution was determined based on conductivity measurements using the conversion factor described in Equation 2 (Tchobanoglous and Schroeder, 1985). 37 M A T E R I A L S A N D M E T H O D S // = 1.6xl(T 5 EC Eq. 2 Where n = Ionic Strength EC = Electric Conductivity (juS/cm) From this value of ionic strength, the activity coefficients for each species of interest was calculated, based on the Guntelberg approximation of the Debye-Hiickel equation shown in Equation 3 (Sawyer et al, 1994). Where: y = the activity coefficient for the species of interest. z = the ionic charge of the species of interest. The second step in determining the solubility products of the produced struvite was to partition the analytically measured compounds into the specific ions present in the water. That is to partition the measured phosphate into PO43", HPO4 2 ", H2PO4", and H3PO4, the measured ammonia into NH3 and NFL;+, and the measured magnesium into M g 2 + and M g O H + . No forms of magnesium phosphate were included in these calculations. Equations 4 to 8 show the dissociation constants which were used for the partitioning at a temperature of 20°C (Ping Liao, pers comm.). These coefficients were adapted and interpolated to 20°C from literature values. l o g r = 0 .5z 2 V^ 1 + V ^ Eq. 3 [ H 2 P 0 4 " ] [ H + ] / [ H 3 P 0 4 ] = 7.81*10 ,-3 Eq. 4 [HP0 4 2"][H+]/[HP0 4"] = 6.12*10"' •8 Eq. 5 [P0 4 3"][H+]/[HP0 4 2"] = 5.00*10 ,-13 Eq. 6 [NH 3][H +]/[NH 4 +] = 6.05 *10 ,-10 Eq. 7 [Mg 2 +][OH"]/[MgOH+] = 2.75*10' ,-3 Eq. 8 38 M A T E R I A L S A N D M E T H O D S These acid and base dissociation constants were then substituted into Equations 9-11 to solve for each individual species concentration. Since all samples were filtered prior to analysis, it was assumed that only dissolved species were present. T-PO4 = [H3PO4] + [H 2 P0 4 -] +[HP0 4 2 "] + [P04 3~] Eq. 9 T - N H 3 = [NH 3] + [NH4+] Eq. 10 T-Mg = [Mg 2 +] +[MgOH+] Eq. 11 Once the activity of each individual species of interest was determined, the solubility product was calculated over a pH range similar to that expected to be encountered in an operating struvite crystallizer. 4.5.2. Struvite Conditional Solubility Product The struvite conditional solubility product (Ps), as defined in this study, is the direct product of the analytical results for soluble magnesium, ammonia nitrogen and ortho-phosphate, as defined by Equation 12, where the [] brackets indicate concentration in moles per liter. There is no attempt to correct for ionic activity in this value; it was simply used as a "quick way" to determine the supersaturation ratio for reactor operation based on field analytical results. Ps = [Mg - T] [NH4 - N] [POA - P] Eq. 12 4.5.3. Supersaturation Ratio The supersaturation ratio (SS ratio) represents the ratio of the conditional solubility product in a solution to the equilibrium conditional solubility product for the given conditions. The equilibrium conditional solubility product used in this study is the one developed using the digester supernatant from the City of Penticton AWWTP. Equation 13 is the relation used to determine the supersaturation ratio where Ps e q indicates the equilibrium conditional solubility product. A solution with a SS ratio greater than 1 is supersaturated with respect to struvite and struvite will be formed to bring the solution to equilibrium; a solution with a SS ratio of less than 1 is undersaturated and struvite crystals wil l melt to bring the solution to equilibrium. 39 M A T E R I A L S A N D M E T H O D S SS Ratio = P s / P S e q Eq. 13 4.5.3.1. Feed supersaturation ratio The feed or influent supersaturation ratio describes the hypothetical supersaturation ratio that would exist in an instantly mixed solution consisting of digester supernatant, magnesium chloride solution and sodium hydroxide solution, in proportions equal to those fed to the reactor. This also implies that this supersaturation ratio is for the solution at a pH equal to that in the reactor. This ratio is said to be hypothetical since these conditions never actually exist in the reactor. This supersaturation ratio is a good means of estimating the driving force for the overall crystallization reaction, but does not represent conditions inside the reactor. 4.5.3.2. Effluent supersaturation ratio Assuming that the crystallization reaction has sufficient time to reach equilibrium, the supersaturation ratio in the reactor effluent should be 1.0. However, since the retention time in the reactor is quite short, it is expected that the reaction wil l not be 100% complete. The effluent supersaturation ratio is used as an indicator of this degree of reaction completion. This ratio is calculated based on analysis of reactor effluent samples. 4.5.3.3. In-reactor supersaturation ratio The supersaturation ratio in the reactor is the factor that governs the actual reaction driving force, and this ratio determines to a certain degree the rate of crystal growth, compared with the rate of crystal nucleation. In essence, high supersaturation ratios in the reactor will lead to excess nucleation and eventually a precipitation reaction, rather than a crystallization reaction. The supersaturation ratio in the reactor for this study has been calculated by combining the concentrations of magnesium, ammonia and ortho-phosphate in the reactor feed and recycle streams. It is therefore representative of the supersaturation ratio in a completely mixed sample drawn from immediately above the injection ports of the reactors. The local supersaturation ratios in the injector port section will undoubtedly differ from this value, due to micro-scale concentration gradients as the reagents mix; however, this value is thought to be representative of the bulk solution properties. 40 M A T E R I A L S A N D M E T H O D S 4.5.4. Recycle Ratio The recycle ratio in this study is calculated using Equation 14. Recycle Ratio = (QrQeVQe Eq. 14 Where: Q t = The total combined flow through the reactor. Q e = The effluent flow from the external clarifier (or the combined feed flows) The recycle ratio therefore represents the ratio of the flow from the recycle pump to the combined flow from the supernatant feed pump and chemical dosing pumps. This recycle ratio is used to control the in-reactor supersaturation ratio by diluting the feed with treated effluent. 4.5.5. Crystal Retention Time For this study, the crystal retention time (CRT) is used as a means of estimating the average amount of time a harvested crystal spends in the reactor. It is calculated by measuring the collapsed bed volume of struvite crystals in the reactor at the time of each harvest, and then calculating the approximate number of days that have passed since that volume of crystals have been removed from the reactor. For example, i f the collapsed bed volume was measured to be 6.6 liters, and 1.1 liters of crystals were harvested from the reactor every two days, then the CRT would be 12 days. Since the crystals were harvested from the reactor at irregular intervals, the CRT was calculated using a log of each harvest date and volume. 4.5.6. Mean Crystal Size The mean crystal size of each harvest was calculated from the sieve analysis. A l l the crystals in each size fraction were assumed to be of a diameter in the middle of the size fraction. That is the crystals that were of less than 0.5 mm were assumed to be 0.25 mm in diameter, the 0.5-1 mm crystals were assumed to have a diameter of 0.75 mm, the 1-2 mm crystals were assumed to have a diameter of 1.5 mm and the crystals that were greater than 2 mm were assumed to have a diameter of 2.5 mm. Based on this assumption the mean diameter by mass was calculated using Equation 15. 41 M A T E R I A L S A N D M E T H O D S M C D = (Ml(0.25) + M2(0.75) + M3(1.5) + M4(2.5))/(M1+M2+M3+M4) Eq. 15 Where:MCD = Mean Crystal Diameter (mm) M l = mass of crystals of diameter less than 0.5 mm. M2 = mass of crystals of diameter from 0.5 to 1 mm M3 = mass of crystals of diameter from 1 to 2 mm M4 = mass of crystals of diameter greater than 2 mm 4.5.7. Percent Phosphate Removal Since the removal of phosphorus is a primary objective of this research, the percentage of phosphate removed from the digester supernatant stream was monitored. This value was calculated using Equation 16. %P removal = ([Pi](Q0- [Pe](Qe))/ ([PiKQO) * 100 Eq 16 Where: [P;] = concentration of PO4 -P in the feed supernatant. [Pe] = concentration of PO4-P in the reactor effluent. Qi —the flow of supernatant into the reactor. 4 2 R E S U L T S A N D D I S C U S S I O N 5. RESULTS AND DISCUSSION The main result of this study was that the reactor design described in Section 3 was successful in recovering phosphate in the form of struvite from a full-scale digester supernatant at the City of Penticton AWWTP. After the initial commissioning and startup phase, the two reactors operated without failure and with little required operator intervention for the duration of the study. By the end of the study, it was possible to let the reactor operate for periods of up to 5 days without any operator intervention. Crystalline product was recovered from the reactor as small pellets, with average diameters approaching 2 mm by the end of the study. These crystals were found to be nearly pure struvite and of a hardness adequate to allow easy separation and processing of the product. The overall operation period of the reactors was from September 2 n d , 2001 to December 13 t h , 2001. However due to the low phosphate content (7.8-18.8 mg/L PO4-P) in the digester supernatant initially, the operation of the reactors prior to October 12 t h, 2002 was essentially a commissioning phase and little phosphorus recovery was possible. During this time, high chemical dosages of both magnesium chloride and sodium hydroxide were necessary to induce the crystallization of struvite and this data is therefore not presented here, other than to say that phosphate removal is possible even at these low concentrations, but at a high unit cost. The following discussion therefore relates to the results obtained during the period of October 12 t h to th December 13 , 2001, except where explicitly noted. 5.1. Struvite Solubility Product Determination Determination of the solubility of struvite in the digester supernatant used in this study will be discussed first, in order to set a baseline for discussions regarding various operational parameters in the reactors; these include supersaturation ratios and reaction completeness. Several authors have attempted to determine a solubility product for struvite, but there is a very wide range of reported solubility values (Dastur, 2001). It was therefore important for this study 43 R E S U L T S A N D D I S C U S S I O N to determine the equilibrium conditions that could be expected in our reactors, when treating real digester supernatant. Using the procedure outlined in Section 4.2, two experiments were conducted; one to determine the struvite equilibrium conditions in distilled water, and the other to determine the equilibrium conditions in digester supernatant. Thermodynamically, there should be a single value of the solubility product (K s p ) that should apply to all solutions, as long as it is possible to determine the activity of each chemical species accurately. Unfortunately, it is difficult to determine the activity of individual compounds in digester supernatant with precision, due to the presence of a myriad of known and unknown compounds. The presence of these compounds also leads to a wide range of possible competing reactions which could skew the solubility product determination. 5.1.1. Struvite Solubility Product in Distilled Water In order to simplify the solution chemistry involved in determining the solubility product of the struvite formed in the reactors in Penticton, a preliminary trial was conducted using distilled water as the solvent. Figure 5.1 shows the negative logarithm of struvite solubility product (pK Sp) calculated over a pH range from approximately 7.0 to 9.5 for distilled water. It can be seen that the solubility product calculated is relatively constant over this range. The mean value of the solubility product in this range was found to be 1.5 X 10"14 with a standard deviation of 3.6 X 10"15. However, when subjected to a least squares regression, the trend line does, in fact, have a slope indicating that the solubility product does change with pH; the slope in the curve is relatively small and the variation in the data makes it difficult to ascertain whether this value is in fact a constant, or whether it varies with pH. In this study, the solubility product was only evaluated out of curiosity, and is not used as a control parameter for the reactor, but simply as a means of comparing results obtained in distilled water to those in digester supernatant. Detailed calculations and data for this determination can be found in Appendix B. 44 R E S U L T S A N D D I S C U S S I O N 14.50 14.40 14.30 14.20 14.10 o- 14.00 05 a- 13.90 13.80 13.70 13.60 13.50 13.40 _D0_ • n • • • • • 6.5 7 7.5 8 8.5 9 9.5 pH 10 • Disti l led Wate r • Digester Supernatant i i Figure 5.1: Struvite solubility product in distilled water and digester supernatant vs. sample pH 5.1.2. Struvite Solubility Product in Digester Supernatant Also shown in Figure 5.1 is the calculated struvite solubility product in digester supernatant from the City of Penticton AWWTP. This solubility product varied from 4.3 X 10"15 to 3.2 X 10"14. There is an obvious change in this value with pH, indicating that there are probably some reactions taking place in the supernatant that were not accounted for in the simplified analysis performed here. Since it was not possible to determine a constant K s p value for struvite in digester supernatant across a wide pH range, it was decided that using the Ps would be a more reasonable way of monitoring the reactor operation, since the calculation of the Ps is much simpler and requires fewer assumptions. 5.1.3. Struvite Conditional Solubility Product As a simple means of determining the saturation state of the supernatant being treated, the conditional solubility product (Ps ) was used. Figure 5.2 shows the experimentally determined struvite Ps curves for distilled water, as well as for digester supernatant. A second order polynomial curve was fitted to the data using Microsoft Excel software, and this curve was used subsequently to represent equilibrium conditions in the solutions. For the supernatant curve, Equation 17 describes this polynomial curve where pPs is the negative logarithm of the 4 5 R E S U L T S A N D DISCUSSION P s . This curve fits the data with a R 2 value of 0.993, indicating that this is an accurate representation of the equilibrium conditions in this particular supernatant. There is a significant difference between the pPs curves for supernatant and for distilled water, mainly due to the difference in ionic strength of the two solutions; however, other factors such as chemicals in the supernatant that may compete with the crystallization or inhibit it, are also at play. In order to eliminate these factors from the analysis, the curve developed using digester supernatant from the Penticton AWWTP was used. Eq. 17 pPs = -0.203pH2 + 4.09 pH-U.76 10.5 -I , , 1 1 1 1 > 1 6 6.5 7 7.5 8 8.5 9 9.5 10 pH • Disti l led Wate r • Supernatant Disti l led Wa te r Supernatant | Figure 5.2: Struvite pPs in digester supernatant and distilled water as a function of pH 5.2. Supernatant Characteristics During the Study Since the operation of the digester at the City of Penticton A W W T P was modified during the course of this study, the composition of the supernatant from the digester changed significantly. Normal operation of the digester involved only the digestion of primary sludge, resulting in P04-P concentrations of 5 to 15 mg/L in the digester supernatant. At the beginning 46 R E S U L T S A N D D I S C U S S I O N of the study (early September), the digester was supplemented with thickened waste activated sludge (WAS) from a thickener tank. This practice appeared to hydraulically overload the digester and it was therefore discontinued until a better solution could be found. During this period, the supernatant contained high suspended solids concentrations (up to 2000 mg/L) and this was causing operational problems for the treatment plant. Following this period of instability, a method of transferring WAS from the gravity belt thickener was devised that allowed the transfer of much thicker sludge (approximately 5% solids). This practice allowed much more WAS to be transferred to the digester without hydraulic overloading and thus allowed the phosphate concentration to increase, without causing suspended solids problems in the supernatant. Once this practice was established in early October, it was possible to maintain much higher phosphate concentrations in the digester, as can be seen in Figure 5.3. 15 c CD c o _ O CL 80.0 70.0 60.0 50.0 40 .0 30.0 500 _- 4 5 0 4 0 0 5 350 300 I e 250 1 200 § O 150 Z 100 | 20.0 10.0 0.0 17-Aug-01 6 -Sep-01 26 -Sep-01 16-Oct-01 5-Nov-01 25-Nov-01 15-Dec-01 4 -Jan-02 Date 50 0 - P 0 4 - P • M g - N H 4 - N Figure 5.3: Digester supernatant composition during the course of the study. The estimated hydraulic residence time of the digester was 28 days; therefore, there was some lag time between the change in operation and the resulting conditions in the supernatant. By adding thickened WAS to the digester on an average of 3 days per week, it was possible to maintain a PO4-P concentration of greater than 50 mg/L. This also coincided with a concerted 47 R E S U L T S A N D D I S C U S S I O N attempt to keep the aluminum containing sludge from the water treatment plant out of the digester, thus allowing higher phosphate concentration to be maintained in the supernatant1. Once the aluminum sludge was eliminated from the digester feed (early October), the concentrations of ammonia and phosphate increase steadily as the WAS content in the digester was increased. The magnesium concentration, however, appeared to remain relatively constant and independent of the ammonia and phosphate concentrations; this is contrary to the belief that magnesium is released in conjunction with phosphate when B N R sludge is digested anaerobically (Doyle, et al 2000; Jardin and Popel 2001). The reasons for this different trend have not been investigated here. During the period from October 12 t h to Dec 13 t h, the concentration of PO4-P ranged from 37 to 71 mg/L, while the NH4 -N concentration ranged from 197 to 436 mg/L and the Mg concentration ranged from 11 to 35 mg/L. Due to the wide variation in the composition of the supernatant being fed to the crystallization reactors, the operation of the reactors was continually modified to maintain stable crystal growth conditions in the reactor. 5.3. Reactor Operation This section describes the results obtained from the operation of the two struvite crystallization reactors at the City of Penticton AWWTP. In general it should be said that the reactors operated as expected and in a manner similar to the operation observed during previous trials with similar pilot-scale reactors using synthetic supernatant (Dastur, 2001). The crystals harvested from the reactor were generally of a darker color and of a smaller diameter than those harvested from synthetic supernatant, but removal and recovery of these crystals was easy and the product handling methods used in the previous trials worked well here. The detailed operational data collected during the study are found in Appendices C and D for reactors A and B respectively. 1 In order to minirnze the aluminum load to the digester, on days when the aluminum-rich drinking water treatment plant sludge was discharged to the wastewater treatment plant, sludge from the fermenters was send directly to the sludge press, thus bypassing the digester. 48 RESULTS A N D DISCUSSION 5.3.1. Mg/NH4/P04 Forms and filtration Several samples were analyzed, both unfiltered and filtered, to determine what portion of the constituents of interest (Mg, NH4 -N , and PO4-P) were associated with suspended solids. Table 5.1 shows the results of this analysis. The influent samples are for settled digester supernatant from the storage tanks, while the effluent samples are for reactor effluent from both reactors. The latter is a good indicator of the presence of small crystals of struvite in the effluent, as well as indicating any chemicals that are adsorbed to colloidal material in the supernatant. Since the dissolved forms of the ions are the ones taking part in the chemical equilibrium reactions within the supernatant, it was the dissolved concentrations that were of interest; therefore, the samples used for the analysis of the performance of the reactors were filtered. Table 5.1: Supernatant filtration analysis and solid fraction determination for reactor influent and effluent. Analyte Unfiltered Filtered Influent Unfiltered Filtered Effluent Influent Influent Solid Effluent Effluent Solid Sample Sample Fraction Sample Sample Fraction M g (mg/L) 25.4 25.5 -0.1 38.9 39.0 -0.1 N H 4 - N (mg/L) 292 281 11 249 238 11 PO4-P (mg/L) 42.8 40.8 2.0 8.0 6.9 1.1 n 4 4 4 8 8 8 In general, a relatively small fraction of all three analytes are associated with the suspended solids, and an equal amount is present in the influent and effluent samples; this indicates that the solid fraction is possibly associated with colloidal material that does not settle out and simply passes through the struvite crystallizing reactors without interacting with the crystals. The only exception is phosphate which has a slightly lower solid fraction in the effluent than the influent. This could be due to analytical error, or the low phosphate concentration in the effluent causing some dissolution of the phosphate associated with colloidal matter. In any case, the difference between the influent and effluent solid fractions was quite small (0.9 mg/L). Interestingly, there was no magnesium present in solid form (with nominal size greater than 1.5 microns); in fact, the analysis shows that some magnesium was added to the solution 49 R E S U L T S A N D D I S C U S S I O N during the filtration process. The difference is quite small, however, and may have been due to sampling or analytical error. 5.3.2. Removal efficiency One of the main objectives of this research was to remove phosphate from the digester supernatant stream, in a full-scale B N R plant. The performance of the two reactors, with respect to removal of phosphate and ammonia from the supernatant stream, is described herein. Magnesium removal was not evaluated, since it was supplemented to the reactor in order to ensure that it was not the limiting reagent in the formation of struvite. Suffice it to say that this dosing can be controlled so that the overall effect of the crystallization reactor can be to either add or remove magnesium from the supernatant. In this study, the magnesium concentration in the feed to the reactor was maintained at a 1.3:1 molar ratio with phosphate. Whether magnesium was added or removed in the process, therefore, depended on the removal of phosphate and the initial concentration of magnesium in the supernatant. Overall, it was possible to control the phosphorus removal efficiency within the range of 30 to 90 %. This control was exerted either by setting the pH in the reactors or by setting the inlet supersaturation ratio. The original objective of the study was to demonstrate that it was possible to remove at least 70% of the phosphate from the digester supernatant stream. As can be seen in Figure 5.4, it was, in fact, possible to control the removal efficiency in the desired range. Variations from the target value were investigated to compare the economics of different removal efficiencies. The two reactors were operated in a parallel mode until November 7 t h, when the operation of Reactor B was modified to purposely achieve lower phosphate removal. With the exception of 1 day, when the magnesium feed to the reactor was accidentally interrupted (Oct 24 t h), the removal of phosphate in Reactor A was maintained above 70%. This shows that it is, in fact, possible to maintain the removal efficiency targeted in this study, and that it was possible to maintain a higher removal efficiency i f desired (>80%) for a supernatant with a phosphate concentration of 40 mg/L or more. These results are consistent with results obtained in several other studies where struvite was being recovered from full-scale digester liquors (Abe, 1995; Munch and Barr, 2001; Ueno and Fujii, 2001) 50 R E S U L T S A N D D I S C U S S I O N 100.00 90 .00 -= 80 .00 CD or CD 1 CL 70.00 60 .00 50 .00 « 40 .00 CL 30.00 20 .00 10.00 0.00 3& 6-Oct-01 16-Oct-01 26-Oct-01 5-Nov-01 15-Nov-01 25-Nov-01 5-Dec-01 1 5 - D e c - 2 5 - D e c -01 01 Date • R e a c t o r A - B - R e a c t o r B Figure 5.4. Percentage phosphate removal for each reactor during the study period. For phosphate removal, two possible factors were evaluated to control the percentage removal; the operating pH of the reactor, and the inlet supersaturation ratio. The first assumes that the variation in the Mg:NH_i:PC)4 molar ratios in the supernatant is small and can therefore be ignored; also, the percentage of phosphorus removed will vary with the operating pH, simply because the solubility of struvite, as defined by the equilibrium Ps, varies with pH. This method of evaluation is by far the simplest and is useful for the day to day operation of the reactor, but would probably fail to accurately predict the performance of a reactor at a new site with different molar ratios. This relation is shown graphically in Figure 5.5. The wide range of removal efficiencies for a given pH (up to 31%) is due to the change in inlet concentrations and changes in the Mg:NFf4:P04 molar ratios over the duration of the study. That is to say, this method of prediction is useful, but simplistic, and will not be sufficient in a supernatant which is highly variable in composition i f precise control of the phosphate removal is required. 51 R E S U L T S A N D D I S C U S S I O N Figure 5.5: Phosphate removal vs. operating pH in the struvite crystallizing reactors. In the second method of predicting the removal of phosphorus, the inlet supersaturation ratio is used. This method assumes that the effluent supersaturation ratio will be unity, indicating that equilibrium has been reached in the reactor. It is therefore possible to predict the effluent phosphate concentration by assuming equimolar removal of M g and NH4 -N . Figure 5.6 shows the percentage of phosphorus removal versus the inlet supersaturation ratio for the operating period in both reactors. The important factors that contribute to the scatter in Figure 5.6 are the inaccuracies in the measurement of the Mg, N H 4 - N and PO4-P concentrations, as well as in the measurement of the pH. The fact that a supersaturation ratio is a function of all four of these measured values makes for a compounded error, but the advantage is that this method allows the prediction of removal efficiency in a widely-varying supernatant composition, with the same accuracy. Overall, the best method to use to predict the phosphate removal from an operational point of view wil l depend on the degree of accuracy wanted and the available data. Basically, a reactor can be controlled to remove the desired amount of phosphate by varying the operating pH or the inlet supersaturation ratio. The difference between the two methods is that the first takes into account only one of the factors involved and is applicable only for a specific supernatant, 52 R E S U L T S A N D D I S C U S S I O N while the latter requires a more complete analysis of the situation and is more generally applicable. CO CO CD a. CD 1 CL CO 2 CL 100.00 90.00 80.00 70.00 60.00 50.00 * 40.00 30.00 20.00 10.00 0.00 • • i # • Olt 0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 Inlet S S Rat io • Reac to r A • Reac to r B Figure 5.6: Phosphate removal vs. inlet supersaturation ratio in the struvite crystallizing reactors. Ammonia concentrations in the digester supernatant in Penticton were several times higher than phosphorus. The average ammonia to phosphate molar ratio in the supernatant during the study period was 13.4:1, with a range of 7.1:1 to 17.2:1. For this reason, the removal of ammonia is not expected to be very high since ammonia and phosphate should be removed in equimolar amounts during the formation of struvite. The removal of ammonia is, however, expected to be slightly higher than phosphate since it is volatile, especially at a basic pH. Figure 5.7 shows the measured removal of ammonia during the course of the study for both reactors. On average, 5.0% and 3.5% of the ammonia was removed from the supernatant in reactors A and B, respectively. The large variation in the removal of ammonia is in part due to the relatively low precision of the analytical method used to determine NH4-N in the field; it is also due to the method of calculation requiring the measurement of several flows as well as the concentrations. On several days, negative removals were calculated for ammonia when evidently struvite was being formed, but this is probably due to analytical error. As discussed previously, replicate field analyses for ammonia were found to vary by as much as 30 mg/L. It is therefore not 53 R E S U L T S A N D DISCUSSION unreasonable that the negative values calculated for ammonia removal could be due to analytical error. 25 .00 20 .00 - 15.00 X 10.00 5.00 0.00 -5.00 -10 .00 -15 .00 6-Oct-01 16-Oct-01 26-Oct-01 5-Nov-01 15-Nov-01 25-Nov-01 5-Dec-01 1 5 - D e c - 2 5 - D e c -01 01 Date • R e a c t o r A -o— R e a c t o r B Figure 5.7: Percentage ammonia removal for each reactor during the study period. 5.3.3. Struvite Recovery In order to ensure that the phosphate being removed from the supernatant was in fact being recovered, the dry weight of each harvest of struvite was recorded, and the final dry weight of struvite in each reactor was recorded at the end of the experiment. These masses are compared with the theoretical mass of struvite that should have been formed, based on the phosphate removed from the digester supernatant in Table 5.2. The struvite that is considered to be recovered in this analysis is the mass weighed after the drying and sieving of the harvested product. Some losses occurred during the process of harvesting, drying, transferring, sieving and weighing the product struvite crystals. Significant accumulation of fine struvite crystals could be seen on the floor around the reactors and the crystal processing areas; however, no attempt was made to quantify these losses. Some additional loss occurred in the sludge wasted from the external clarifier. This sludge mass was not analyzed or weighed, but it was visually observed to contain fine crystalline material which was periodically discarded. Another source of error is that this analysis assumes that the reactors were operating 24 hours a day, when in fact they were shut down daily to harvest crystals, monitor the collapsed bed depth of crystals, clean the injector 5 4 R E S U L T S A N D DISCUSSION ports, and calibrate the pH probes. On average, these shutdown periods are estimated to be 1 hour per day or 4% of the time. Table 5.2 shows that between 86 and 87 percent of the phosphate removed was recovered. Correcting these values for the estimated shutdown time brings the recovery rates to between 90 and 91 percent. Taking into account the relatively small mass of struvite produced and the amount of handling and process losses over the course of 3 months of study, this recovery is higher than expected. In a full-scale crystallization installation, it is expected that the losses would represent a smaller fraction of the produced struvite due to the larger scale involved, and recovery of processing losses as they accumulate on floors. Table 5.2: Comparison of theoretical struvite production and actual struvite recovery. 5.3.4. Reactor Struvite Loading An attempt was made to operate the two reactors at the same struvite loading rate. The struvite loading rate is defined here as the theoretical mass of struvite that should be grown based on the daily mass of phosphate removed in each reactor. Figure 5.8 shows the struvite loading rates of both reactors during the study period. Generally, the struvite loading rates of the two reactors were similar, except for during two periods, November 11 t h to 12 t h, and November 21 s t to 28 t h. The differences in loading rates applied to the reactors were mostly due to difficulty in maintaining constant flow rates through the reactors, due to changing water levels in the storage tanks, but also partly due to the changes in the supernatant's composition. Reactor A Reactor B Struvite Harvested (kg) 7.82 Struvite Left in Reactor (kg) 3.80 Total Struvite Recovered (kg) 11.62 Theoretical Struvite Produced (kg) 13.54 % Struvite Recovered 86 6.50 4.35 10.85 12.52 87 55 R E S U L T S A N D D I S C U S S I O N 350.0 300.0 250.0 200.0 150.0 | 100.0 to 50.0 0.0 co I ? T3 (0 O f A**s*» I k ' y i i i i i i I I 6-Oct-01 16-Oct-01 26-Oct-01 5-Nov-01 15-Nov-01 25-Nov-01 5-Dec-01 1 5 - D e c - 2 5 - D e c -01 01 Date • R e a c t o r A - B — R e a c t o r B Figure 5.8: Reactor struvite loading during the study period. 5.3.5. Supersaturation Ratio Figures 5.9 and 5.10 show the feed, in-reactor, and effluent supersaturation ratios for reactors A and B, respectively. The most notable difference between the supersaturation ratios is Figures 5.9 and 5.10 are in the influent supersaturation ratios. This is due to the lower targeted recovery in Reactor B. Since Reactor B was operated at a lower pH, while maintaining the same Mg:P molar ratio as Reactor A , the influent supersaturation ratio is lower in Reactor B. This allowed more supernatant to be pumped through the reactor at a lower recycle ratio, while maintaining the same struvite loading rate. Overall, by maintaining relatively constant struvite loading rates in both reactors, the in-reactor SS ratios and the effluent SS ratios remain quite similar in both reactors. It can be seen from Figures 5.9 and 5.10 that the in-reactor SS ratio varies independently of the inlet SS ratio. This is attributed to the fact that the inlet SS ratio simply describes the potential for recovery from the supernatant at the operating conditions of the reactor, whereas the in-reactor SS ratio describes the actual conditions in the reactor, including the effect of the effluent recycle stream. 56 R E S U L T S A N D D I S C U S S I O N 25 .00 20 .00 .9 15.00 co co 10.00 5.00 0.00 • • •_» -•—•--• ° n - n a AAA** .DA ITB_ • .-•pn_"P" G M G n u n n n n n _ n n n n n o a - „ n n A D " " n n n n D n n •••a ana_ ••.• a annnng a6-Oct-01 16-Oct-01 26-Oct-01 5-Nov-01 15-Nov-01 25-Nov-01 5-Dec-01 1 5 - D e c - 2 5 - D e c -01 01 Date • Inlet S S Rat io • In Reac to r S S Rat io A Effluent S S Rat io Figure 5.9: Reactor A supersaturation ratios during the study period. 25 .00 20 .00 .9 15.00 I CO w 10.00 5.00 An D i BP5~ ^ A ^ A 8_____°AA° ____ °D_BHWH_g8 2 2 2 - - -«88_ g 8H-8 a »nHB-^ 0.00 6-Oct-01 16-Oct-01 26-Oct-01 5-Nov-01 15-Nov-01 25-Nov-01 5-Dec-01 1 5 - D e c - 2 5 - D e c -01 01 Date • Inlet S S Rat io • In Reac to r S S Rat io A Effluent S S Rat io Figure 5.10: Reactor B supersaturation ratios during the study period. 5.3.5.1. Relation between in-reactor and effluent SS ratios For greater clarity, the in-reactor and effluent supersaturation ratios for Reactors A and B are shown again in Figures 5.11 and 5.12, respectively. In these figures, it is easier to see that these two values appear to be correlated. 57 R E S U L T S A N D D I S C U S S I O N 5.00 4 .50 4 .00 3.50 o 3.00 ro OH 2 .50 CO w 2.00 1.50 1.00 0.50 0.00 • n • u • n A A A n °° °° ADDD° D A D A D D • ^ n n n A ° A • A • • • U A ° ° ° ° O n " n ° A D Q n A N A A A A A A A A . • • u A A A A A A A A A A A A A A A F L A * A A A A A A A A A A A A A A A 6-Oct-01 16-Oct-01 26-Oct-01 5-Nov-01 15-Nov-01 25-Nov-01 5-Dec-01 15-Dec-01 25-Dec-01 Date • In Reac to r S S Rat io A Effluent S S Rat io Figure 5.11: Comparison of in-reactor SS ratio with effluent SS ratio for Reactor A . There are two possible reasons for the correlation between in-reactor and effluent SS ratios. The first is that the bulk of the variation in these SS ratios may come from errors in the measurement of pH and the dissolved constituents of the effluent. Since these values are all used in the computation of both SS ratios, an error in any or all of these values will affect both the in-reactor and effluent SS ratios. 5.00 4 .50 4 .00 3.50 o 3.00 ro OH 2 .50 co w 2.00 1.50 1.00 0.50 0.00 A° -oe-• D • • nn_ n B_ A • ° ••• A A A A Q B A N N N ND • _noH • • A A A a A • &AAA° ^ T * ^ A A A A A A A A A AAAA""A A A 7A^ A~~ 6-Oct-01 16-Oct-01 26-Oct-01 5-Nov-01 15-Nov-01 25-Nov-01 5-Dec-01 15-Dec-01 25-Dec-01 Date • In Reac to r S S Rat io A Effluent S S Rat io Figure 5.12: Comparison of in-reactor SS ratio with effluent SS ratio for Reactor B. 58 R E S U L T S A N D D I S C U S S I O N The second explanation is that the reactors are operating near their kinetic limit for struvite loading and that any increase in struvite loading wil l result in an increased effluent supersaturation. In an under-loaded reactor, it is expected that equilibrium will have time to establish itself and the effluent should therefore have a supersaturation ratio approaching unity. In this case the reactor loading rate will have little effect on the effluent supersaturation ratio. In an overloaded reactor, however, the solution will not have time to reach equilibrium and therefore the higher the reactor loading, the higher the effluent supersaturation ratio will be. In order to determine whether the correlation between in-reactor and effluent SS ratios are due to analytical error, or due to the reactor loading exceeding its kinetic limit, the effluent SS ratios are plotted against the in-reactor SS ratios and against the struvite loading rate in Figures 5.13 and 5.14, respectively. Figure 5.13 shows that there is an evident correlation between the supersaturation ratio in the reactor and in the effluent. This is as expected from general observation of Figures 5.11 and 5.12 and the previous discussion. This shows that an increased supersaturation in the effluent occurs concurrently with an increased supersaturation in the reactor, but does not necessarily show that one is the cause of the other. Both possible causes (increased loading, or measurement error) could be responsible for the correlation. In order to evaluate the possibility of increased loading causing the increased effluent supersaturation ratio, the effluent supersaturation ratio is plotted against the struvite loading rate of each reactor in Figure 5.14. From Figure 5.14, it can be seen that there is, in fact, no correlation between the struvite loading rate of each reactor and the effluent supersaturation ratio. This would tend to indicate that the reactor is under-loaded, since the effluent supersaturation does not respond to an increased struvite loading. This also infers that the changes in effluent supersaturation ratios are probably due mainly to the compounded measurement error in each individual reading of pH, Mg, N H 4 - N and PO4-P. This also implies that the effluent supersaturation should, in fact, always be approaching unity and that the differences between the measured values and unity could be corrected for. Further investigation, involving more meticulous analysis of replicate samples, could be useful in determining this with more certainty. 59 R E S U L T S A N D D I S C U S S I O N 3.5 3.0 2.5 ro a. co co 2.0 1.5 1.0 0.5 0.0 0.00 ° • • • ° 1.00 2.00 3.00 In-Reactor S S Rat io 4 .00 • Reac to r A • Reac to r B 5.00 6.00 Figure 5.13: The relationship between the in-reactor and effluent supersaturation ratios. 3.5 3.0 2.5 8. CO CO "E CD e Ul 2.0 1.5 1.0 0.5 0.0 0.0 • • • 1 U ^ A 50.0 100.0 150.0 200 .0 250 .0 Struvite Load ing Rate (g/day) 300 .0 350.0 • Reac to r A • Reac to r B Figure 5.14: The relationship between reactor struvite loading rate and effluent supersaturation ratio. In any case, the effluent supersaturation ratio in reactors A and B average 1.11 and 1.43, respectively. One interesting factor is that an error of 0.1 in the pH reading can cause a change of over 0.3 in the SS ratio. Considering that the accuracy of the pH meters used was ±0.1 and that these probes were observed to drift significantly over time, the measurement of pH may be 6 0 RESULTS AND DISCUSSION the main source or error in the determination of the SS ratios. Statistically, the effluent SS ratio in Reactor A is not different from 1.0 at the 99% confidence level, while the effluent SS ratio is greater than 1 in Reactor B at the 99% confidence level. It is difficult to explain why the effluent SS rations in both reactors are different. Since both reactors were constructed in the same manner and were operated in a similar manner, it was expected that both reactors would have a similar effluent SS ratio. The most likely cause for this difference would be a drift in the pH reading from one of the reactors, since the SS ratio is so sensitive to pH. It is unlikely that this is due to excess loading as previously discussed, and because there was little struvite encrustation in the reactors effluent piping. It is believed therefore that the effluent SS ratios were, in fact, approaching unity in both reactors. 5.3.6. Crystal Retention Time Crystal Retention Time (CRT) was developed as a means of monitoring the mean time that a struvite crystal spends in the reactor. It was expected that this factor could be correlated to crystal size, since longer growing times should lead to larger crystals. The CRT in the reactors varied from 12 to 47 days using the method of calculation described in Section 4.5.5. Figure 5.15 shows the calculated CRT for each harvest from the two reactors. The increasing trend at the beginning of each curve results from the low feed phosphate concentration at the beginning of the study, causing slow growth rates. Due to these slow growth rates, the CRT of the early crystals was quite high, since harvesting of the reactor only occurred once the reactor was fully loaded. 61 R E S U L T S A N D D I S C U S S I O N 50.0 45.0 40.0 35.0 £ 30.0 CO Q 25.0 fc or o 20.0 15.0 10.0 5.0 0.0 6-Oct-01 16-Oct-01 26-Oct-01 5-Nov-01 15-Nov-01 25-Nov-01 5-Dec-01 15-Dec-01 25-Dec-01 Date • Reac to r A • Reac to r B Figure 5.15: CRT calculated for all harvested crystals during the study period. Since the CRT of the early crystals were not thought to be representative of the actual age of the harvested crystals until one full CRT had elapsed, the subsequent analysis of the crystals in Section 5.5 is focused on the crystals harvested after at least one full reactor volume was harvested. This means that the CRT range analyzed in this study effectively ranges from 12 to 21 days. A longer term study with more regular harvesting intervals would be necessary in order to fully examine the effect of CRT on product size, but a preliminary investigation is completed in Section 5.5. 5.3.7. Operational Problems This section describes several of the day to day operational problems that were encountered during the study and the solutions that were found to mitigate these problems. Overall, most of these problems were quite minor and several of them were due to the small scale of the equipment and the temporary nature of the installation. 5.3.7.1. Plugging of tubing On several occasions, the tubing leading from the external clarifier to the recycle pump and to the drain was found to be encrusted with struvite. This encrusted layer would sometimes break away from the tubing walls and accumulate in low spots in the tubing. These 62 R E S U L T S A N D D I S C U S S I O N accumulations occasionally resulted in flow reductions or overflow of the external clarifier. This problem was solved by simply flexing the tubing at the point of obstruction; this broke up the obstruction and allowed normal flow to be resumed. To prevent this type of obstruction, the tubing was regularly flexed or impacted at the points where the accumulation was observed and the problem did not recur. 5.3.7.2. Reactor fouling Encrustation of the reactor walls with struvite was also observed. This caused the clear piping used in the reactors to become coated with an opaque layer and prevented the observation of the particle movement and the monitoring of the collapsed and expanded crystal bed heights. A stiff brush on a telescoping pole was used periodically to clean the interior walls of the reactor. It was found that this was only necessary in the harvest section of the reactor, once the reactor was fully loaded with crystals. Although the reactor walls in the upper sections of the reactor did slowly accumulate a struvite crust, it typically broke off by itself before completely obstructing the view into the reactor. Even in the harvest section or the reactor, this cleaning was only required a few times per month. 5.3.7.3. Injector port fouling The injector port was the section of the reactor most prone to struvite encrustation, since the highest local supersaturation ratios occurred there. Although this section was regularly cleaned, occasionally the encrustation obstructed the flow through this section. The flow was never stopped completely due to encrustation, but the flow of magnesium chloride solution and sodium hydroxide was occasionally dramatically reduced. The feed and recycle flows through the reactor were also occasionally reduced, due to the reduction in diameter of the injector port section. 5.3.7.4. Feed flow regulation Even though positive displacement pumps were used, the change in pump head between the full level and the empty level in the supernatant feed tanks caused variations in supernatant feed flow of up to 25%. This was partially due to the fact that the feed pumps were operated 63 R E S U L T S A N D D I S C U S S I O N near their minimum flow capacities. This problem was minimized by adjusting the pump speed daily. In a full-scale process, it is expected that this problem would be minimal with the use of on line flow control. 5.3.7.5. Suspended solids control Due to the variable suspended solids content of the digester supernatant, it was necessary to allow sufficient settling time for the supernatant in the feed tanks to prevent solids carryover into the crystallization reactors. The settling of the suspended solids in the supernatant was always rapid, and there was never much residual solids in the settled supernatant. In general, the settling was easy due to the presence of excess storage capacity; however, in a full-scale installation, it would be important to have a sedimentation tank installed between the digester and the crystallizing reactors, in order to prevent the solids from entering the reactors. 5.3.7.6. Caustic solution storage and strength depletion With the passage of time, the caustic solution was observed to decrease in strength; that is, a larger volume of caustic was needed to maintain a given pH in the reactors as the solution aged. This was probably due to the contamination of the solution with carbon dioxide from the air since the chemical storage tanks were not isolated from the atmosphere. This led to an increased use of sodium hydroxide beyond what would normally be expected i f a properly designed storage tank was used; however, no attempt to estimate this over-consumption was made in this study. This correction would reduce the chemical usage costs somewhat from the values discussed in Section 5.7. 5.3.7.7. Magnesium chloride dosing rate The magnesium chloride dosing rate measured in this study was overestimated due to a faulty method of measurement. The flow rate of magnesium chloride into each reactor was measured by inserting the end of the feed tubing into the bottom of a graduated cylinder and recording the change in volume over a minute. Unfortunately, the presence of the tubing in the graduated cylinder displaces a significant portion of the volume and therefore the actual volume 64 R E S U L T S A N D D I S C U S S I O N pumped was overestimated. This may explain why the calculated amount of magnesium removed in the reactor exceeds the amount of phosphate removed on a molar basis. 5.4. Reactor Performance Model A model was developed to predict the effluent magnesium, ammonia and ortho-phosphate concentrations from a struvite crystallizing reactor, such as the one used in this study. The model inputs are the operating pH of the reactor, as well as the magnesium, ammonia and ortho-phosphate concentrations in the combined feed to the reactor. The model assumes that pure struvite is being formed (i.e. that magnesium, ammonia and ortho-phosphate are removed in equimolar amounts), and that the reactor effluent is at equilibrium as described by pPs in Equation 17. Equation 18 is the general equation used by the model, where A represents the molar reduction in the concentrations of Mg, N H 4 - N and PO4-P; [Mg]jn, [NH4]jn and [P04]jn represent the concentrations of magnesium, ammonia and ortho-phosphate in the combined influent to the reactor; and Ps e q is the equilibrium Ps as described by Equation 17. This equation is solved iteratively for A, and the resulting effluent concentrations from the reactor are then predicted as the combined influent concentrations minus A. ([Mg],, - AX[P04]„ - A)dNH4]in - A) = PSeq Eq. 18 In order to verify the model, it was used to predict the effluent concentrations of both reactors during the course of the experiments at the City of Penticton AWWTP. The model was used to predict the effluent concentrations of magnesium, ammonia and phosphate, based on the collected data for the combined influent and the operating pH of each reactor. Figures 5.16 to 5.21 show the comparison of the model results to the measured effluent concentrations. The detailed model calculations and the analysis of the model results can be found in Appendix E. Figures 5.16 and 5.17 compare the modeled and measured concentrations for phosphate in the effluents from Reactor A and Reactor B, respectively. In general, the model predicts the effluent phosphate concentrations quite well. The average absolute error in the modeled effluent phosphate concentration for Reactors A and B were 1.8 mg/L and 4.6 mg/L, respectively. The 65 R E S U L T S A N D D I S C U S S I O N model appears to under-predict the effluent phosphate concentration at lower pH values, which is the reason for the larger absolute error in Reactor B, especially later in the experimental run. This may be due to an error in pH reading or due to the fact that the effluent from Reactor B averaged an SS ratio of 1.4 and the model assumes that this value is 1.0. As discussed previously, these two factors are related and the error in pH reading could be the cause of the elevated effluent SS ratio. Figures 5.18 and 5.19 compare the modeled and measured concentrations for ammonia in the effluents from Reactor A and Reactor B, respectively. Both of these graphs show very good correlation between the modeled and measured values. The average absolute error in the modeled effluent ammonia concentration for Reactors A and B were 13.1 mg/L and 12.8 mg/L, respectively. This error is approximately equal to the relative standard deviation found in the analytical determination of ammonia. Figures 5.20 and 5.21 compare the modeled and measured concentrations for magnesium in the effluents from Reactor A and Reactor B, respectively. Considering that the influent magnesium concentration is calculated using the combination of the magnesium concentrations in the feed supernatant and feed magnesium chloride solution, as well as the measured flows of these two, the predicted effluent concentrations match the actual vales quite closely. The average absolute error in the modeled effluent magnesium concentration for reactors A and B were 7.1 mg/L and 6.1 mg/L, respectively. The error measurements described above are the averages of the absolute value of the error between the predicted and measured values. Since the measured values are, themselves, expected to contain some experimental error, a more representative value of the model error may be the average of the errors between the predicted and measured values, without taking the absolute values. Table 5.3 shows the comparison between the error as calculated by absolute values, and by actual values in mg/L and in percentage of the measured values. 66 R E S U L T S A N D D I S C U S S I O N 3 0 _ . 2 5 c q S •e CD O c o O 3 0. 2 0 15 10 5 0 6-Oct-01 16-Oct-01 26-Oct-01 5-Nov-01 15-Nov-01 25-Nov-01 5-Dec-01 15-Dec-01 25-Dec-01 Da te - Actua l Effluent - » - P r e d i c t e d Effluent Figure 5.16: Modeled and actual effluent phosphate concentrations for Reactor A. 60 „ 5 0 =d i 1 _r 4 0 o _ 3 0 8 c c j 2 0 3 Q. 1 A IT mmat 1 1 1 1 1 1 1 10 0 6-Oct-01 16-Oct-01 26-Oct-01 5-Nov-01 15-Nov-01 25-Nov-01 5 -Dec-01 15-Dec-01 25-Dec-01 Date -Ac tua l Effluent - * - Pred ic ted Effluent Figure 5.17: Modeled and actual effluent phosphate concentrations for Reactor B 67 R E S U L T S A N D D I S C U S S I O N 4 0 0 x 100 50 0 -I 1 1 1 1 1 1 1 1 6-Oct-01 16-Oct-01 26-Oct-01 5-Nov-01 15-Nov-01 25-Nov-01 5-Dec-01 15-Dec-01 25-Dec-01 Date —•—Actual Effluent -m— P red ic ted Effluent Figure 5.18: Modeled and actual effluent ammonia concentrations for Reactor A . 5 0 0 z 100 50 0 -I 1 1 1 1 — 1 1 1 1 6-Oct-01 16-Oct-01 26-Oct-01 5-Nov-01 15-Nov-01 25-Nov-01 5-Dec-01 15-Dec-01 25-Dec-01 Date - •—Ac tua lE f f l uen t - " — P r e d i c t e d Effluent Figure 5.19: Modeled and actual effluent ammonia concentrations for Reactor B 68 R E S U L T S A N D D I S C U S S I O N D ) E C o c cu o c o o 8 0 7 0 6 0 50 4 0 30 20 10 0 6-Oct-01 16-Oct-01 26-Oct-01 5-Nov-01 15-Nov-01 25-Nov-01 5-Dec-01 15-Dec-01 25-Dec-01 Date \ N -Ac tua l Effluent P red ic ted Effluent Figure 5.20: Modeled and actual effluent magnesium concentrations for Reactor A . E, c o E 8 c o O 70 60 50 4 0 30 2 0 10 0 6-Oct-01 16-Oct-01 26-Oct-01 5-Nov-01 15-Nov-01 25-Nov-01 5-Dec-01 15-Dec-01 25-Dec-01 Da te -Ac tua l Effluent - * - Pred ic ted Effluent Figure 5.21: Modeled and actual effluent magnesium concentrations for Reactor B. 69 R E S U L T S A N D D I S C U S S I O N Table 5.3: Comparison of average model error absolute and actual values. Criteria Average Relative Average Actual Relative Actual Absolute Error Absolute Error Error (mg/L) Error (%) (mg/L) (%) Reactor A M g 7.1 26.1 2.9 12.7 Reactor A N H 4 13.1 4.8 -2.3 -0.9 Reactor A P 0 4 1.8 18.8 -0.7 -8.2 Reactor B M g 6.1 18.2 -1.5 -2.8 Reactor B N H 4 12.8 4.4 -4.8 -1.2 Reactor B P 0 4 4.6 22.0 -4.0 -19.3 The use of the actual error values, rather than the absolute error values, tends to reduce the reported relative error i f the error is not systematic; that is, i f the error is normally distributed. In this study, all of the relative errors were reduced dramatically when actual errors are considered as compared with absolute errors, with the exception of the error in phosphate prediction in Reactor B. This is attributed to the fact that the predicted phosphate concentration in Reactor B is systematically lower than the actual value, especially at lower pH's. 5.5. Struvite Product Characteristics Another important factor to investigate in this study was the characteristics of the harvested struvite crystals. Three major factors were investigated in this regard: the size of the harvested crystals, the apparent density of the crystals in the reactor and the chemical composition of the harvested crystals. The crystals were also examined under an optical microscope and a scanning electron microscope (SEM). 5.5.1. Struvite Crystal Size In general, it was found that the size of the harvested crystals was continuously increasing during the course of the study, even after several complete reactor volumes had been harvested. Figure 5.22 shows the mean crystal diameter of each harvest from both reactors, during the course of the study. With time, the crystals grew stronger and larger. One of the most important factors in determining the final diameter of the crystals was their structural strength, since the early crystals tended to break easily during the harvesting, drying and sieving 70 R E S U L T S A N D D I S C U S S I O N operations. The crystals harvested late in the study, on the other hand, did not tend to break much during these handling processes. These results imply that several complete CRT's must have elapsed before a steady state crystal size will be reached, as suggested by Takiyama et al. (1997). In fact, the mean crystal diameters shown in Figure 5.22 do not appear to be approaching their steady state values, even after two months of operation. Similar results are reported by Abe (1995). Further studies of longer term would be necessary to determine the final steady state size the struvite crystals can be expected to reach. From the data collected in this study, the mean crystal diameter grew by an average of 0.016 mm per day. E 1-8 £ 1.6 CD N w 1.4 S 1.2 O 1 oo 0.8 oo i CO X 0.6 £ 0.4 0.2 • 6-Oct-01 16-Oct-01 26-Oct-01 5-Nov-01 15-Nov-01 25-Nov-01 5-Dec-01 15-Dec-01 25-Dec-01 Date • Reactor A • Reactor B Figure 5.22: Mean crystal diameter of struvite crystals harvested during the study. Other factors that were evaluated to determine their effect on mean crystal diameter were the CRT and the SS ratio in the reactor. Figures 5.23 and 5.24 show the relation between these two factors and the mean crystal size. In general, the trends in these two graphs are much less definite (as evidenced by the low R 2 values); however, the theoretically expected trends do appear. 71 R E S U L T S A N D D I S C U S S I O N 1.8 E ^ 1 . 6 i_ & CD I 1-4 CD b 11.2 o TO 1 CD 0.8 0.6 ; 0 . 0 4 x + 0 . 6 1 R 2 = 0.16 11 13 15 17 C R T (Days) 19 21 23 Figure 5.23: Mean harvested crystal diameter vs. CRT for each harvest. E E, a> cu E CD Q 3 o c CD a> 2 2 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 y = -0 .57x + 2.41 R^ = 0.18 1.5 1.7 1.9 2.1 S S Rat io 2.3 2.5 2.7 Figure 5.24: Mean harvested crystal diameter vs. average in-reactor SS ratio. It is expected that the longer the CRT, the larger the crystals will get. On average, it was found that the crystals grew by 0.04 mm per day of CRT, as shown in Figure 5.23. This trend is quite variable, indicating that the CRT may not be the most important factor in determining the final size of the harvested crystals. It is, however, expected that there is a certain minimum CRT that wil l be required to get a given size of crystals. Since several other factors including the supernatant composition, the operating pH, the in-reactor SS ratio and the harvesting frequency 72 R E S U L T S A N D D I S C U S S I O N were all varied at the same time as the CRT, further studies which maintain all other factors constant would be necessary to determine the exact effect of CRT on mean crystal diameter. The generally accepted theory in crystallizer engineering is that the average size of the produced crystals varies inversely with the supersaturation ratio at which the crystallizing solution is maintained. Figure 5.24 shows that an inverse relationship between SS ratio and crystal size did seem to exist in this study. The mean crystal diameter was found to decrease by 0.56 mm for a unit increase in in-reactor SS ratio. As with the analysis of crystal size vs. CRT, however the SS ratio was not varied independently from the other factors and further studies would be required to assess the exact role of the SS ratio on the crystal size. 5.5.2. Struvite Crystal Bulk Density Although the density of the crystals was not measured directly in this study, an interesting trend was observed in the mass of crystals removed from the harvest section of the reactor with time. For each harvest, the flow through the reactor was stopped and the fluidized crystals were allowed to settle before the harvest zone was isolated with the ball valves and the crystals were withdrawn from the reactor. In this manner, a constant volume of 1.1 liters of crystals was harvested each time. It was noticed throughout the study that the crystal mass harvested from this volume was consistently increasing with time. Figure 5.25 shows this trend. The first harvests in the study had a total mass of approximately 200 g, while the final harvests had a mass of approximately 600 g. This increasing trend did not appear to be reaching a maximum by the end of the study. In general, the crystal mass harvested was increasing by approximately 7 grams per day of reactor operation. This increase in mass harvested coincided with the increase in diameter of the harvested crystals. Visual analysis of the crystals, presented in Section 5.5.4, shows that this increased bulk density of the crystals was probably due to the change in shape of the crystals over the course of the study, from friable plate like aggregates, to harder rounded crystal roses. 73 R E S U L T S A N D D I S C U S S I O N 700 .0 fc? 600 .0 ^ 500 .0 400 .0 300.0 200.0 100.0 0.0 —* u »n » ° 8 * 6-Oct-01 16-Oct-01 26-Oct-01 5-Nov-01 15-Nov-01 25-Nov-01 5-Dec-01 1 5 - D e c - 2 5 - D e c -01 01 Date • Reac to r A • Reac to r B Figure 5.25: Harvested crystal mass from the 1.1L harvest zone over the course of the study. 5.5.3. Struvite Crystal Composition In order to verify the composition of the crystals grown in this study, 29 samples of crystals were analyzed as described in Section 4.3. Each size fraction (<0.5 mm, 0.5-lmm, 1-2mm and >2mm) of harvests, from 3 dates, from each reactor, were analyzed. The detailed data from this analysis is shown in Appendix F. Table 5.4 shows the average crystal compositions as compared to the expected theoretical composition of pure struvite and the estimated struvite content of the crystals. The estimated struvite content was calculated by averaging the ratios of measured to theoretical composition of Mg, N , and P for each sample. Table 5.4: Average results of crystal composition analysis. % Mean Standard Theoretical Composition Deviation Value for by Mass Pure Struvite M g 9.9 0.4 9.9 N 5.6 0.3 5.7 P 12.8 0.6 12.6 Struvite (est.) 99.8 4.0 100.0 The results in Table 5.4 show that the crystals harvested from the reactors were essentially pure struvite. The crystal samples were also analyzed for content of Fe, A l , K , and 74 R E S U L T S A N D D I S C U S S I O N Ca. These were thought to be the most likely metals that would be found in the struvite crystals as impurities. Table 5.5 shows the average results of the crystal analysis for impurities. Again, the detailed data is presented in Appendix F. The main impurity found in the crystals was calcium, and it was only present at an average of 0.5% by weight. Based on this limited analysis, the produced crystals are therefore believed to be composed mostly of pure struvite. Further analysis of the crystals should be performed for heavy metals and pathogens, to determine i f the product is appropriate for direct use as an agricultural fertilizer. Table 5.5: Struvite crystal impurity content. % Content By Weight Mean Standard Deviation Ca 0.49 0.32 K 0.04 0.01 Fe 0.03 0.02 A l * * * Most A l analyses were below the detection limit of the method used. 5.5.4. Microscope and SEM Crystal Examination In order to better understand reasons for the observed changes in harvested crystal sizes and densities, samples of the crystals were observed, first under a microscope at 40X magnification, and then by SEM. A preliminary microscope observation was used as a method of screening the samples and finding general trends, in order to be able to select representative samples for further analysis by SEM. In general, it was found that the appearance of the crystals changed significantly with time. The early crystals appeared to be a loose aggregation of plate like crystals, which explains why the crystals tended to break apart during the drying and screening processes. Over the course of the study, the crystals grew more rounded and more solidly aggregated. In the crystals from the final harvests, the crystals are very rounded and appeared to be monolithic under microscope examination at 40X. S E M analysis of these crystals shows that all of the crystals are, in fact, aggregates of smaller crystals; the later crystals are simply more solidly aggregated. Figure 5.26 shows S E M images of crystals which were retained on a 1 mm sieve, but passed a 2 mm sieve. The images on the left are of crystals harvested from Reactor A , while 75 R E S U L T S A N D D I S C U S S I O N those on the right are from Reactor B. A l l images are at 50X magnification and the bar in the bottom right of each image represents 1 mm. The top row of images are of crystals harvested in October, the middle row of images are of crystals harvested in November and the bottom row of images are of crystals harvested in December. The progression in the crystal morphology is quite striking when looking at these images. The crystals appear to progress from loosely aggregated crystals in October, to tightly packed, and more solidly bound crystal balls in December, especially in Reactor B. The crystal from December in Reactor A appears to be similar to the crystal from November in Reactor B. The outside faces of these crystals (Reactor B November and Reactor A December) appear to be similar to the crystal from December in Reactor B; however, their cores appear to be weaker. This may have caused the clumps of hard surface crystals to break away, either due to turbulence and impacts in the reactor, or during the drying and sieving operations. These images seem to indicate that the strength and shape of the crystal aggregate change slowly with each complete CRT, since the broken pieces of the older crystals appeared to form the core of the new crystals. These images can also be used to explain the difference in the bulk densities of the harvested crystals, as discussed previously. The later crystals appear to be much rounder and more filled in, thus allowing the crystals to pack in more tightly to the harvest zone, when flow through the reactor is stopped. This, in turn, would cause the harvested mass to increase as observed. 76 R E S U L T S A N D D I S C U S S I O N Figure 5.26: S E M images of crystals retained on a 1 mm sieve, but passing a 2 mm sieve at 50X magnification. Top left: harvested October 28 from Reactor A ; middle left: harvested November 18 from Reactor A ; bottom left: harvested December 11 from Reactor A ; top right: harvested October 17 from Reactor B; middle right: harvested November 18 from Reactor B; bottom right: harvested December 12 from Reactor B. 77 R E S U L T S A N D D I S C U S S I O N In Figure 5.27, crystals from the four size fractions collected on December 11 from Reactor B are shown. These images are interesting because they show that the crystals in the smaller size fractions appear to be broken pieces of larger crystals, as predicted by Mersmann (1999) for large crystal systems. Unfortunately, this does not show i f this breakage occurs in the reactor, or during the drying and sieving process. It is quite likely that most of this breakage occurs in the sieving operation, since this operation involves some relatively strong abrasion. It is also unlikely that the smaller crystal particles would be found in the harvest zone of the reactor, due to the high fluid upflow velocity and their displacement by the larger particles in the fluidized bed. Figure 5.27: S E M images of crystals harvested from Reactor B on December 11 at 50X magnification. Top left: crystal retained on 2 mm sieve; top right: crystal retained on 1 mm sieve; bottom left: crystals retained on 0.5 mm sieve; bottom right: crystals passing 0.5 mm sieve. 78 R E S U L T S A N D D I S C U S S I O N Close inspection of the bottom left image in Figure 5.27 reveals that the individual crystal surfaces on the inside of the crystal show an ortho-rhombic shape and are growing from the center of the crystal outwards. This could lead to the conclusion that the stripes observed on the surface of the whole crystals may in fact be the tips of these ortho-rhombic crystals, which are rounded off by the abrasion in the fluidized bed and in the sieving process. The stripes described above can be more clearly seen under higher magnification, as shown in Figure 5.28. Under 300X magnification, the surface no longer appears as smooth as under 5 OX magnification, and it appears that the crystal is made up of tightly-agglomerated, smaller, brick-like crystals. If this image is considered in conjunction with the bottom left image in Figure 5.27, we can begin to appreciate that these square formations on the surface of the crystals may, in fact, be the tips of the plate like surfaces observed on the broken crystals. Under 3000X magnification, the surface of each individual crystal tip becomes more resolved, and it becomes apparent that these crystal surfaces are covered with cracks and fissures (as shown in Figure 5.28). It is unclear i f these cracks and fissures are inherent in the crystals, or i f they are a product of the drying process. The crystals were dried using a ceramic space heater, which caused the temperature of the crystals to increase. Although the surface temperature of the crystals was never measured, they were observed to be quite warm to the touch at times. This heating, and the subsequent cooling, could lead to thermal cracking of the crystals, as well as to the expulsion of some of the ammonia or water molecules from the struvite crystal matrix. The crystallography of the recovered crystals was not analyzed in depth, but simply observed visually, and since the crystals were grown under continually varying conditions, it is impossible to determine the exact cause of the changes in the appearance of the crystals. It would also be impossible to predict the appearance of crystals from future works based on this study, especially considering that the crystals grown in this study are very different from those grown in ongoing studies at U B C using synthetic supernatant in similar reactors (Ali Adnan, Masters Student, U B C Civil Engineering, pers. comm.). Further studies, under tightly controlled conditions, would probably be necessary to determine the cause and effect relationships leading to the final shape and size of the produced crystals. It may be sufficient to empirically determine 79 R E S U L T S A N D D I S C U S S I O N the conditions leading to the production of crystals with the desired characteristics for their final use. Figure 5.28: S E M images of a crystal retained on the 1 mm sieve, harvested from Reactor B on Dec 11. Magnified at 50X (top), 300X (middle), and 3000X (bottom). 80 R E S U L T S A N D D I S C U S S I O N 5.6. Treated Supernatant Phosphate and Ammonia Reductions A preliminary analysis was performed to determine the effect of installing a full-scale struvite crystallizing reactor on the phosphate and ammonia loads applied to the BNR treatment train at the City of Penticton AWWTP. In order to accomplish this, a preliminary mass balance was performed on total phosphorus through the treatment plant, based on data from the year 2000. The mass balance shows that 97.6% of the total phosphorus entering the plant is removed from the liquid stream, and thus transferred to the sludge stream. This represents 65.8 kg of total phosphorus per day. Of this mass, only 8.9 kg per day were estimated to be released from the sludge and returned to the headworks of the treatment plant with the digester supernatant, during the course of this study. This return represents approximately 13% of the phosphorus load to the treatment plant. A rough estimate shows that the phosphorus load from the digester supernatant would increase to 33% of the influent phosphorus load, i f 100% of the W A S was digested. This value is significantly lower than the 80% found by Niedbala (1995). One of the main reasons for this discrepancy is probably the practice of disposing of aluminum-rich, drinking water treatment sludge to the wastewater treatment plant, which began after the study by Niedbala. This aluminum load appears to cause the treatment plant to operate as a combined biological/chemical phosphorus removal plant, where the removed phosphorus is much less susceptible to resolubilization under anaerobic digestion, as described by Jardin and Popel (2001). If a full-scale struvite recovery reactor were to be installed, it may be beneficial to cease dumping the drinking water treatment plant sludge to the wastewater treatment plant, in order to maximize the amount of recoverable phosphorus in the digester supernatant stream. Also, maximizing the amount of secondary sludge that can be digested would allow for a maximum of phosphorus to be removed from the sludge stream. The following discussion evaluates changes in ammonia and phosphorus loads that could be expected in the treatment plant, should a full-scale struvite recovery system be installed and 81 R E S U L T S A N D D I S C U S S I O N operated under conditions similar to those in this study; that is with the digestion of approximately 40% of the secondary sludge along with the primary sludge. 5.6.1. Ammonia Load form the Digester Supernatant Digesting secondary sludge caused the digester supernatant ammonia concentration to increase from 270 mg/L as N to 400 mg/L as N . This concentration is then reduced by an average of 50 mg/L in the struvite crystallizing reactor. The net result of the process is, therefore, to increase the ammonia concentration by approximately 80 mg/L. Since the average daily digester supernatant flow was 80 m 3 , this increased ammonia concentration would represent an increased ammonia load of approximately 6.4 kg/day to the treatment plant. 5.6.2. Phosphorus Load From the Digester Supernatant Digesting secondary sludge caused the digester supernatant phosphate concentration to increase from 10 mg/L as P to 70 mg/L as P. This concentration is then reduced to between 5 and 30 mg/L as P in the struvite crystallizing reactor depending on the desired percent recovery. Assuming that 80 % recovery is achievable, the net result of the process is, therefore, to increase the phosphorus concentration in the supernatant returned to the B N R process by approximately 4 mg/L. At the average daily digester supernatant flow, this increased phosphorus concentration represents an increased load of approximately 0.3 kg/day to the treatment plant. It would also reduce the phosphorus content of the sludge being shipped off site to the composting facility by approximately 4.5 kg/day, or 6.8%. In order to improve the removal efficiency of this process, a larger portion of the phosphorus in the sludges would have to be released in the digester. In this study, only 8.5% of the phosphorus removed in the treatment plant was present in the form of ortho-phosphate in the digester supernatant. By increasing the portion of soluble ortho-phosphate in the digester supernatant, it would be possible to recover a larger amount of phosphorus and nitrogen in the struvite crystallizing reactors; thus reducing the loads on the treatment plant, and recovering a larger amount of product. 82 R E S U L T S A N D D I S C U S S I O N 5.6.3. Estimated Full-scale Struvite Production Based on the data collected in this study, it is estimated that a full-scale struvite recovery operation treating only 40% of the secondary sludge in conjunction with the primary in the City of Penticton AWWTP would produce between 25 and 45 kg of struvite per day, depending on the efficiency desired (50-90% P recovery). This amounts to between 9.1 and 16.4 metric tons of struvite per year. 5.7. Financial Estimates Based on the pilot scale work, some basic estimates of the operating costs and savings that could be expected in a full-scale operation are outlined here. It is important to note that these results are very rough estimates, and that capital costs are not included. In order to aid in the estimation of the expected capital costs, an equipment list for full-scale implementation is included, but estimated prices have not been obtained for this equipment. The operating costs outlined in this section assume that the wastewater treatment plant is operated in the same manner as during the later part of this study (i.e. November and December of 2001). A l l cost estimates are in Canadian dollars. 5.7.1. Capital Infrastructure Requirements A significant investment in equipment and piping would be required in order to implement a full-scale struvite recovery system at the City of Penticton AWWTP. Although no attempt was made to quantify this cost, a summary of the required equipment is listed in the following section for reference, along with available information relating to the sizing of this equipment. 5.7.1.1. Digester upgrade Digester upgrade requirements depend on the quantity of WAS that will be treated and the current excess capacity of the digester. Alternatives include modifying the digester for operation in the thermophillic temperature range to reduce the required HRT, or building a new digester to handle the increase in hydraulic and organic load. Further study of this aspect would 83 R E S U L T S A N D D I S C U S S I O N be required to determine the exact needs. A study by Niedbala (1995) found that a reduction in the HRT of the digesters from 20 days to 10 days had little impact on the digesters performance. Current common design practice is to design for 15 day retention time in digesters. Since the existing digesters have a retention time of approximately 28 days, digester upgrades may not be required. 5.7.1.2. WAS dewatering and transfer to digester Some modification to the WAS thickening and dewatering equipment would be required to allow trouble free transfer of thickened WAS to the digester. Transfer pumps and piping will also be required for a permanent installation since the current piping does not allow for this. 5.7.1.3. Supernatant transfer to settling and storage A permanent method of transferring the digester supernatant to a settling and equalization tank will be required for the full-scale installation, since no permanent winterized system currently exists. This would include a pump and piping capable of transferring and estimated intermittent flow of 90 m3/day. 5.7.1.4. Supernatant settling and storage Since the supernatant occasionally contains high solids concentrations, a facility to remove these solids is required. Also, since the digester flow is intermittent, a storage/equalization tank is required to allow a continuous feed to the struvite crystallizer. A volume of at least 90 m 3 would be advisable to allow storage of supernatant during maintenance shutdowns. A typical secondary clarifier design, with a floating decanter, should be adequate to allow storage, settling and sludge withdrawal. Sizing would depend on a study of the settling characteristics of the solids, as well as desired equalization volume. Existing decommissioned clarifiers on site would be likely candidates for this role. 5.7.1.5. MgCl storage, batch dilution and dosing Storage for concentrated MgCl solution would be required. Volume would be decided based on desired shipping frequency. A batch dilution system would be desirable to avoid 84 R E S U L T S A N D D I S C U S S I O N excessive concentration gradients in the injection port area of the reactor. Variable flow dosing pumps would also be required to control the M g dosing to the reactor. The estimated usage of magnesium chloride would be 15 metric tons per year as magnesium chloride hexahydrate. The existing unused chemical storage tanks on site could be used for this purpose, i f the magnesium chloride was delivered in bulk tanker trucks in liquid form. 5.7.1.6. NaOH storage, batch dilution and dosing Storage for concentrated NaOH solution would be required. Volume would be decided based on desired shipping frequency. The storage tank should be properly designed for sodium hydroxide storage and isolated from the carbon dioxide in the atmosphere, to avoid depletion of the caustic strength. A batch dilution system would be desirable to avoid excessive pH gradients in the injection port area of the reactor. Variable flow dosing pumps with a pH controller would also be required to control reactor pH. The estimated usage of sodium hydroxide would be between 5 and 12 metric tons per year, depending on the desired operating pH of the reactor. A purpose-built tank would be required for this task, since no existing tanks have the required safety precautions and carbon dioxide traps for sodium hydroxide storage. 5.7.1.7. Reactor feed and recycle pumps with flow control A feed pump capable of delivering 90 m3/day of supernatant at 20 feet of head with low shear is required. This pump should be equipped with a variable frequency drive and a flow meter, to be able to control the feed flow rate. A recycle pump capable of delivering 1-10 times the feed flow with low shear, variable frequency drive and flow meter for flow control is also required. This pump would be subjected to a low head difference (piping head loss only). The requirement for low shear pumps is due to the potential for the formation of struvite deposits on the pump impellers i f high shear conditions induce pH increases due to the degassing of C O 2 . Alternatively, the pumps should be equipped with easily cleaned impellers that are not prone to excessive wear when scaled. 85 R E S U L T S A N D D I S C U S S I O N 5.7.1.8. Struvite crystallizing reactor Depending on the phosphate removal efficiency desired, the full-scale reactor will have diameters between 10 to 12.5 times those of the pilot reactor. The heights of the reactor zones could remain the same as those of the pilot reactor, and the valves in the harvest zone can probably be eliminated and replaced with an online crystal withdrawal system. The external clarifier can probably also be eliminated, since it serves a redundant purpose i f the recycle is drawn from the top clarifier. This practice would also reduce the overflow velocities in the top clarifier, making settling more efficient there. The full-scale reactor could fit comfortably in the existing chemical storage building on site in Penticton, where a lime silo was originally designed to fit. This lime silo was never constructed since chemical phosphorus removal was never needed at the treatment plant. 5.7.1.9. Chemical injector section The injection port section would need to be redesigned to allow for the larger chemical flows while, maintaining rapid mixing characteristics and allowing easy removal for cleaning and maintenance. Multiple injection points should be considered for both magnesium and caustic, to minimize supersaturation gradients in the injector section. For supernatants with higher phosphate concentrations, it may be beneficial to separate the magnesium and caustic injection points to further decrease the supersaturation gradient in each injector zone. This should lead to more uniform crystal growth conditions and less injector scaling problems. 5.7.1.10. Product screening and drying Facilities to separate the product crystals from the liquid stream and dry them are required. Either a rotating drum screen or a parabolic screen could be used for this purpose. Testing of these devices would be required to determine the optimum configuration. The product crystals can either be air dried or heat dried, depending on the time allowed for the drying to occur; further investigation at larger scale would be required to determine the optimum configuration. In this study, the harvested crystals were heat dried in under 24 hours in a 10 mm deep static pile. 86 R E S U L T S A N D D I S C U S S I O N 5.7.1.11. Product packaging and shipping Once the product is dried, a decision has to be made as to whether the product will be shipped in bulk containers or packaged on site. This would depend on the targeted market and whether a central product processing facility, such as a fertilizer producer, is anticipated. Regardless, an area to store the produced struvite will be required until a sufficient quantity is accumulated for economical shipping to market or further processing. Roll-off bins similar to those used to haul dewatered sludge off site could easily be used for this purpose. 5.7.2. Operating Costs The operating costs outlined here are based on information gathered during the course of the pilot study. Detailed calculations of these costs can be found in Appendix G. Operating costs are provided for two scenarios, one for 80 % phosphate removal and one for 60% phosphate removal from a supernatant containing 70 mg/L of ortho-phosphate and approximately 400 mg/L of ammonia. These scenarios are comparable to the operation of Reactors A and B, respectively, during the course of this study. For easy reference, the scenarios are identified as Scenario A and B, to represent 80% and 60 % removal, respectively. 5.7.2.1. Chemical costs A significant portion of the operating costs for this type of struvite recovery operation would come from the chemical costs for magnesium chloride and sodium hydroxide. Prices for sodium hydroxide and magnesium chloride hexahydrate were assumed to be $500 and $200 per metric ton of solid, respectively. The dosing of magnesium chloride for this cost estimation was assumed to be equimolar to the phosphate concentration in the supernatant; the excess molar ratio of magnesium to phosphate is assumed to come from the magnesium already present in the supernatant. For sodium hydroxide the usage was estimated for each reactor over an 18 day operating period. The difference between the requirements for each reactor is due to the difference in operating pH's. Table 5.6 shows the estimated chemical usage costs for the two scenarios. 87 RESULTS AND DISCUSSION Table 5.6: Chemical costs. Scenario MgCl Cost NaOH Cost Struvite Chemical Costs ($/day) ($/day) Produced (kg/day) ($/kg struvite) A 8.26 16.57 40 0.62 B 8.26 7.44 30 0.53 5.7.2.2. Labour costs Labor requirements for the operation of this reactor are estimated at 0.63 persons per day; compared with 0.7 persons per day as found by Kumashiro et al. (2001). The details of the estimated labor requirement calculations can be found in Appendix G. Assuming a labor cost of $50 000 per year for a five day work week, the cost of labor for the facility would be $44 000 per year. This amounts to a cost of $3.03 and $4.04 per kg of struvite produced for Scenarios A and B, respectively. This shows that the labor requirement may be the largest cost associated with the production of the struvite. It should be noted that this cost is expected to stay relatively constant for a larger facility, therefore reducing the unit labor cost of struvite in larger facilities. 5.7.3. Savings and Revenues Sources of savings and revenues expected from the operation of a full-scale struvite recovery facility in Penticton include the sale of the product struvite, the reduction in shipping costs for dewatered sludge and the reduction in polymer usage for dewatering the sludge. Current estimates of the market value of struvite vary widely from country to country and are therefore difficult to identify with any accuracy. This study assumes that the price of struvite product will be $730 per metric ton. Table 5.7 shows the estimated cost savings expected from Scenarios A and B; detailed calculations can be found in Appendix G. Table 5.7: Cost savings and revenues. Scenario Sale of Product Reduction in Reduction in Savings and ($/kg struvite) Sludge Shipping polymer use revenues ($/day) ($/day) ($/kg struvite) A 0.73 18.34 100 3.69 B 0.73 18.34 100 4.67 88 R E S U L T S A N D DISCUSSION 5.7.4. Net Process Savings The overall operating savings expected from the operation of a full-scale struvite recovery process similar to the one described in this report at the City of Penticton AWWTP is shown in Table 5.8. These values translate into a total annual savings of $580 and $1090 for Scenarios A and B, respectively. The bulk of the costs come from the labor to run the reactor, while the bulk of the savings come from the reduction in polymer usage to dewater WAS. Table 5.8: Overall process savings for full-scale struvite recovery. Scenario Chemical Costs Labor Costs Savings and Net Savings ($/kg struvite) ($/kg struvite) Revenues and Revenues ($/kg struvite) ($/kg struvite) A 0.62 3.03 3.69 0.04 B 0.53 4.04 4.67 0.10 Several process changes could be implemented to improve the cost-benefit ratio. These include increasing the mass of struvite recovered by increasing the percentage of WAS digested, reducing the aluminum load to the wastewater treatment plant from the drinking water treatment plant. These modifications would cause the concentration of phosphate in the supernatant to increase, thus allowing more struvite to be produced. This in turn would reduce the unit cost of labor and caustic, as well as increasing the benefit from reduced sludge hauling, and product sale. The effect of this on polymer usage would need to be investigated. Further cost reductions could be achieved by using air stripping for pH adjustment, thus reducing or eliminating the need for caustic; however, this would cause an increase in electrical cost to operate a blower, and the reactor design would need to be modified and tested. Another important factor to consider is that by recovering phosphate from our wastewaters, we would be reducing our dependence on the limited global supply of phosphate rock, and extending the availability of this essential non-renewable resource. The ultimate social cost of the depletion of our phosphate reserves has yet to be determined; however, suffice it to say that should our phosphate reserves be exhausted, intensive agriculture as we know it today would cease to exist and the global food supply would, therefore, diminish significantly. 89 C O N C L U S I O N S 6. SUMMARY AND CONCLUSIONS Based on the results obtained from this pilot-scale study on struvite recovery from a full-scale anaerobic digester supernatant at the City of Penticton A W W T P in British Columbia, Canada, the following conclusions can be drawn: • The pilot-scale struvite recovery reactor developed at U B C was effective in removing phosphate from anaerobic digester supernatant stream, under controlled conditions and produced a product consisting of nearly pure struvite. • By controlling the operating pH of the reactors and the inlet supersaturation ratio, the percentage removal of ortho-phosphate in the reactor was varied between 42% and 91%. The study's target ortho-phosphate reduction of at least 70% was easily achieved. • A model was developed which predicts effluent magnesium, ammonia and ortho-phosphate concentrations from the reactor, based on the influent concentrations of these ions and the operating pH of the reactor. The model assumptions are that the effluent from the reactor is at equilibrium and that the reductions in magnesium, ammonia and ortho-phosphate are equimolar. • During the course of the study, 90 to 91% of the removed phosphorus was recovered after harvesting, drying and screening operations. Most of the loss of mass is expected to be due to sludge wasted from the external clarifier and processing losses during the harvesting, drying and screening operations. • A preliminary analysis of the costs and savings associated with the operation of a full-scale struvite recovery reactor, operating in the same manner as the pilot reactors in the last months of this study, shows that the process savings slightly exceed the process costs. This analysis only included chemical costs, labor costs and savings associated with product sale, reduced sludge shipping and reduced polymer usage. Further savings could be realized with the processing of more secondary sludge and better phosphorous recovery. If a larger portion of the WAS from the treatment plant was digested, a larger amount of struvite could potentially 90 C O N C L U S I O N S be recovered; also by reducing the aluminum input (water treatment sludge is currently processed in the anaerobic digester) to the treatment plant, a larger portion of the phosphorus entering the plant could be recovered. • A preliminary solubility product determination for the produced struvite crystals gave significantly different results for distilled water and digester supernatant. A conditional solubility product developed was useful in predicting reactor efficiency and in operating the reactor. In order to accurately predict the operational efficiency of the reactor, measurements of pH, conductivity, magnesium, ammonia and ortho-phosphate are required. • Although present, scaling on the reactor and piping walls was not problematic during the course of this study. The use of flexible walled tubing allowed the accumulated scale deposits in the piping to be easily removed, and frequent (bi-weekly) cleaning of the injection port section of the reactor prevented complete blockage of the chemical injection points. • After an initial commissioning period, the operation of the reactors was trouble free and they could be operated without intervention for periods of up to five days. The main requirements for labor were for filling chemical dosing tanks and harvesting the product. • The produced struvite crystals were easily separated from the liquor, and were composed of nearly pure struvite (99.8%), with small amounts of calcium, and traces of potassium and iron. The mean diameter, and bulk density of the harvested crystals increased continuously over the course of the study. The mean diameter of the harvested crystals varied from 0.5 to 1.8 mm. S E M examination of the crystals suggested that this was due to changes in the structure of the crystal aggregates over the course of the study; however, it was not clear whether these changes were due to a crystal maturation process, or to changes in the operating conditions of the crystallizers. • The size and hardness of the struvite crystals were affected by the crystal retention time in the reactor, the supersaturation ratio in the reactor and the elapsed time from reactor startup. It was not possible to determine the exact effect of each of these parameters from this study, since they were not varied independently. 91 R E C O M M E N D A T I O N S 7. RECOMMENDATIONS Based on the experience gained from this pilot-scale study on struvite recovery from a full-scale anaerobic digester supernatant, the following recommendations are put forth: • Longer-term studies would be needed to determine the steady-state struvite crystal size and morphology, since a steady state was not reached during this study. This study should also attempt to keep reactor conditions, such as in-reactor SS ratio and CRT, constant and harvest crystals at regular intervals. • The desired size, density, strength and composition of the product crystals, based on the expected market for the crystals, should be determined. This information would allow the evaluation of the effects of various reactor conditions relative to a target product quality. • A study of the effect of the SS ratio in the reactor on the harvested crystal size and morphology would be useful in determining the optimum operating range for crystal growth. • A study of the effect of the CRT on the harvested crystal size and morphology would be useful in determining the optimum operating range for crystal growth. • Air stripping of carbon dioxide shows much promise as a means of cheaply adjusting the pH in the reactor. A reactor design incorporating an air stripping component should be investigated. • In order to gain a better understanding of the hydraulics in the reactor, an investigation into the struvite crystal bed porosity and fluidization characteristics would be useful. This increased knowledge of the hydraulics could be used to develop a kinetic model of the crystallization reactions occurring in the reactor. • A tracer test should be conducted on a fully loaded (i.e. full of struvite crystals) reactor to accurately determine the hydraulic residence time distribution of the reactor. This information would also help in the development of a kinetic model of the crystallization reactions. 92 RECOMMENDATIONS • Further studies varying the hydraulic residence time in the reactor, as well as the fluidization velocities, would be useful in determining the minimum reactor volumes and maximum flow rates that can be achieved without sacrificing reactor performance. • A full-scale study would be necessary to examine the impacts that struvite recovery will have on the process performance and stability of a B N R treatment plant. • A full-scale struvite recovery study at a wastewater treatment plant experiencing excessive struvite scaling in the sludge handling piping would be needed to accurately determine the impact of struvite recovery on the scaling problem. • An investigation into the possibility of digesting a larger portion of the WAS and reducing the processing of aluminum-rich sludges to the City of Penticton A W W T P would be useful in evaluating the potential for increased P and N recovery. • A permanent, full-scale installation would be the ideal way to evaluate many of the long-term questions raised by this study and would allow a more thorough investigation into the actual costs and savings. 93 R E F E R E N C E S 8. 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Element Analyzed Magnesium Iron Ca lc ium A l u m i n u m Potassium Concentration Units mg /L mg/L mg/L mg/L M g / L Instrument Mode Absorbance Absorbance Absorbance Absorbance Emission Sampling Mode Autonormal Autonormal Autonormal Autonormal Autonormal Calibration Mode Concentration Concentration Concentration Concentration Concentration Measurement M o d e Integrate Integrate Integrate Integrate Integrate Replicates Standard 3 3 3 3 3 Replicates Sample 3 3 3 3 3 Wavelength 202.6 248.3 nm 422.7 n m 309.3 nm 766.5 nm Range 0-100 mg/L 0-10 mg/L 0-60 mg /L 0-20 mg /L 0-10 mg/L Flame Type N 2 0 / C 2 H 2 A i r / C 2 H 2 N 2 0 / C 2 H 2 N 2 0 / C 2 H 2 A i r / C 2 H 2 Calibration Algor i thm N e w Rational N e w Rational N e w Rational N e w Rational N e w Rational Table A-2 Instrument operational parameters for flow injection analysis. Ion Analyzed P 0 4 - P N H 3 - N Concentration Units mg /L M g / L Range 0-100 mg /L 0-100 mg/L Temperature 63°C 63°C Method Ammonia Phenate Molybdate Reference 1 2 1: LaChat Instruments Methods Manual for the Qu ikChem Automated Ion Analyzer (1990). Qu ikChem method number 10-115-01-1Z 2: A P H A , A W W A , W P C F (1995). Method 4500 -NH 3 -F . Phenate Method 99 APPENDIX B APPENDIX B: KSP DETERMINATION DATA AND CALCULATIONS 100 A P P E N D I X B Solubi l i ty Tr ia ls Us ing D iges ter Superna tan t and Struvi te g rown in Pent ic ton S a m p l e data P H Conduct iv i ty M g N H 4 - N P 0 4 - P M g NH4-N PO4 -P amp le u S / c m mg /L mg /L m g / L mo l /L mo l /L mol /L S1 6 .45 5060 129.6 378 158.5 0 .00533 0.027 0 .00512 S 2 6.49 5060 130.0 363 156^1 0 .00535 0.026 0 .00504 S 3 6.54 4 8 3 0 113.9 333 144.8 0 .00469 0 .024 0 .00468 S 4 6.66 4 8 1 0 86.9 383 106.9 0 .00358 0 .027 0 .00345 S 5 6.7 4 8 0 0 89.1 369 109.0 0 .00367 0 .026 0 .00352 S 6 6.81 4 5 5 0 74.7 333 87.4 0 .00307 0 .024 0 .00282 S 7 7.05 4 0 9 0 53.1 283 64.7 0 .00218 0.020 0 .00209 S 8 7.44 3920 30.9 304 36.2 0 .00127 0.022 0 .00117 S 9 7.59 3 9 7 0 27 .5 244 32.8 0 .00113 0.017 0 .00106 S 1 0 7.85 3 7 1 0 23.6 384 25.4 0 .00097 0.027 0 .00082 S11 7.85 3 9 8 0 21.0 274 23.1 0 .00086 0 .020 0 .00075 S 1 2 7.92 3380 17.9 355 .0 21.7 0 .00074 0 .025 0 .00070 S 1 3 8.02 3630 18.6 369 17.8 0 .00077 0.026 0 .00057 S 1 4 8.07 3280 20.1 368 18.0 0 .00083 0.026 0 .00058 S 1 5 8.11 3270 18.2 363 17.7 0 .00075 0.026 0 .00057 S 1 6 8.12 3490 19.4 363 15.9 0 .00080 0.026 0.00051 S 1 7 8.14 3320 14.5 356 16.9 0 .00059 0 .025 0 .00055 S 1 8 8.23 3320 16.7 364 14.3 0 .00069 0.026 0 .00046 S 1 9 8.29 3460 14.8 353 14.9 0.00061 0 .025 0 .00048 S 2 0 8.48 3850 15.4 2 2 0 16.5 0 .00063 0.016 0 .00053 S21 8.52 3 4 9 0 11.3 327 10.9 0 .00046 0 .023 0 .00035 S 2 2 8.6 3 5 6 0 12.1 341 12.4 0 .00050 0.024 0.00040 S 2 3 8.72 3 6 5 0 11.1 2 2 5 14.2 0 .00046 0.016 0 .00046 S 2 4 8.97 3 6 2 0 9.3 2 8 9 9.8 0 .00038 0.021 0 .00032 101 A P P E N D I X B M g : P N : P Mo la r Mo la r Struvi te amp le Rat io Rat io P s S1 1.0 5.3 7 .4E -07 S 2 1.1 5.1 7 .0E -07 S 3 1.0 5.1 5 .2E -07 S 4 1.0 7.9 3 .4E -07 S 5 1.0 7.5 3 .4E -07 S 6 1.1 8.4 2 . 1 E - 0 7 S 7 1.0 9.7 9 . 2 E - 0 8 S 8 1.1 18.6 3 .2E -08 S 9 1.1 16.5 2 . 1 E - 0 8 S 1 0 1.2 33.4 2 . 2 E - 0 8 S11 1.2 26 .2 1.3E-08 S 1 2 1.1 36.2 1.3E-08 S 1 3 1.3 45 .9 1.2E-08 S 1 4 1.4 45 .2 1.3E-08 S 1 5 1.3 45 .4 1.1E-08 S 1 6 1.6 50 .5 1.1E-08 S 1 7 1.1 46 .6 8 .3E -09 S 1 8 1.5 56.3 8 .2E -09 S 1 9 1.3 52.4 7 .4E -09 S 2 0 1.2 29 .5 5 .3E -09 S21 1.3 66.4 3 .8E -09 S 2 2 1.2 60.8 4 . 8 E - 0 9 S 2 3 1.0 35.1 3 .4E -09 S 2 4 1.2 65 .2 2 . 5 E - 0 9 Struvi te P h o s p h a t e D issoc ia t ion C o n s t a n t s p P s k a ! k a 2 k a 3 6.1 7.81 E-03 6 1 2 E - 0 8 5 E - 13 6.2 7.81 E-03 6 1 2 E - 0 8 5 E - 13 6.3 7.81 E-03 6 1 2 E - 0 8 5 E - 13 6.5 7.81 E-03 6 1 2 E - 0 8 5 E - 13 6.5 7.81 E-03 6 1 2 E - 0 8 5 E - 13 6.7 7.81 E-03 6 1 2 E - 0 8 5 E - 13 7.0 7.81 E-03 6 1 2 E - 0 8 5 E - 13 7.5 7.81 E-03 6 1 2 E - 0 8 5 E - 13 7.7 7.81 E-03 6 1 2 E - 0 8 5 E - 13 7.7 7.81 E-03 6 1 2 E - 0 8 5 E - 13 7.9 7.81 E -03 6 1 2 E - 0 8 5 E - 13 7.9 7.81 E -03 6 1 2 E - 0 8 5 E - 13 7.9 7.81 E -03 6 1 2 E - 0 8 5 E - 13 7.9 7.81 E -03 6 1 2 E - 0 8 5 E - 13 8.0 7.81 E -03 6 1 2 E - 0 8 5 E - 13 8.0 7.81 E -03 6 1 2 E - 0 8 5 E - 13 8.1 7.81 E-03 6 1 2 E - 0 8 5 E - 13 8.1 7.81 E -03 6 1 2 E - 0 8 5 E - 13 8.1 7.81 E-03 6 1 2 E - 0 8 5 E - 13 8.3 7.81 E-03 6 1 2 E - 0 8 5 E - 13 8.4 7.81 E-03 6 1 2 E - 0 8 5 E - 13 8.3 7.81 E-03 6 1 2 E - 0 8 5 E - 13 8.5 7.81 E-03 6 1 2 E - 0 8 5 E - 13 8.6 7.81 E-03 6 1 2 E - 0 8 5 E - 13 102 A P P E N D I X B A m m o n i a M g O H [H +] [OH1 [Mg + 1 [NH4*] [ P 0 4 ~ ] a m p l e ka kb mol /L mo l /L mo l /L mol /L mol /L S1 6 . 0 5 E - 1 0 2 . 7 5 E - 0 3 3 .5E -07 2 . 8 E - 0 8 5 . 3 E - 0 3 2 . 7 E - 0 2 1.1E-09 S 2 6 . 0 5 E - 1 0 2 . 7 5 E - 0 3 3 .2E -07 3 . 1 E - 0 8 5 . 4 E - 0 3 2 . 6 E - 0 2 1.2E-09 S 3 6 . 0 5 E - 1 0 2 . 7 5 E - 0 3 2 . 9 E - 0 7 3 . 5 E - 0 8 4 . 7 E - 0 3 2 . 4 E - 0 2 1.4E-09 S 4 6 . 0 5 E - 1 0 2 . 7 5 E - 0 3 2 . 2 E - 0 7 4 . 6 E - 0 8 3 . 6 E - 0 3 2 . 7 E - 0 2 1.7E-09 S 5 6 . 0 5 E - 1 0 2 . 7 5 E - 0 3 2 . 0 E - 0 7 5 .0E -08 3 . 7 E - 0 3 2 . 6 E - 0 2 2 . 1 E - 0 9 S 6 6 . 0 5 E - 1 0 2 . 7 5 E - 0 3 1 .5E-07 6 . 5 E - 0 8 3 . 1 E - 0 3 2 . 4 E - 0 2 2 . 6 E - 0 9 S 7 6 . 0 5 E - 1 0 2 . 7 5 E - 0 3 8 . 9 E - 0 8 1.1E-07 2 . 2 E - 0 3 2 . 0 E - 0 2 4 . 8 E - 0 9 S 8 6 . 0 5 E - 1 0 2 . 7 5 E - 0 3 3 . 6 E - 0 8 2 . 8 E - 0 7 1 .3E-03 2.1 E-02 1.0E-08 S 9 6 . 0 5 E - 1 0 2 . 7 5 E - 0 3 2 . 6 E - 0 8 3 .9E -07 1 .1E-03 1.7E-02 1.5E-08 S 1 0 6 . 0 5 E - 1 0 2 . 7 5 E - 0 3 1.4E-08 7 . 1 E - 0 7 9 . 7 E - 0 4 2 . 6 E - 0 2 2 . 4 E - 0 8 S11 6 . 0 5 E - 1 0 2 . 7 5 E - 0 3 1.4E-08 7 . 1 E - 0 7 8 . 6 E - 0 4 1 .9E-02 2 . 1 E - 0 8 S 1 2 6 . 0 5 E - 1 0 2 . 7 5 E - 0 3 1 .2E-08 8 . 3 E - 0 7 7 .4E -04 2 . 4 E - 0 2 2 . 4 E - 0 8 S 1 3 6 . 0 5 E - 1 0 2 . 7 5 E - 0 3 9 .5E -09 1 .OE-06 7 .7E -04 2 . 5 E - 0 2 2 . 6 E - 0 8 S 1 4 6 . 0 5 E - 1 0 2 . 7 5 E - 0 3 8 .5E -09 1.2E-06 8 . 3 E - 0 4 2 . 5 E - 0 2 3 .0E-08 S 1 5 6 . 0 5 E - 1 0 2 . 7 5 E - 0 3 7 .8E -09 1.3E-06 7 .5E -04 2 . 4 E - 0 2 3 .3E-08 S 1 6 6 . 0 5 E - 1 0 2 . 7 5 E - 0 3 7 .6E -09 1.3E-06 8 . 0 E - 0 4 2 . 4 E - 0 2 3 .0E -08 S 1 7 6 . 0 5 E - 1 0 2 . 7 5 E - 0 3 7 .2E -09 1.4E-06 5 . 9 E - 0 4 2 . 3 E - 0 2 3 .4E -08 S 1 8 6 . 0 5 E - 1 0 2 . 7 5 E - 0 3 5 .9E-09 1.7E-06 6 . 9 E - 0 4 2.4 E-02 3 .6E -08 S 1 9 6 . 0 5 E - 1 0 2 . 7 5 E - 0 3 5 .1E-09 1.9E-06 6 . 1 E - 0 4 2 . 3 E - 0 2 4 . 3 E - 0 8 S 2 0 6 . 0 5 E - 1 0 2 . 7 5 E - 0 3 3 .3E -09 3 .0E -06 6 .3E -04 1.3E-02 7 .6E-08 S21 6 . 0 5 E - 1 0 2 . 7 5 E - 0 3 3 . 0 E - 0 9 3 .3E -06 4 . 6 E - 0 4 1 .9E-02 5 .6E-08 S 2 2 6 . 0 5 E - 1 0 2 . 7 5 E - 0 3 2 . 5 E - 0 9 4 . 0 E - 0 6 5 .0E -04 2 . 0 E - 0 2 7 .7E-08 S 2 3 6 . 0 5 E - 1 0 2 . 7 5 E - 0 3 1.9E-09 5 .2E -06 4 . 6 E - 0 4 1 .2E-02 1.2E-07 S 2 4 6 . 0 5 E - 1 0 2 . 7 5 E - 0 3 1 .1E-09 9 . 3 E - 0 6 3 .8E -04 1 .3E-02 1.5E-07 103 A P P E N D I X B {Mg+ +} Sample mol/L 51 1 .9E-03 5 2 1 .9E-03 5 3 1 .7E-03 5 4 1 .3E-03 5 5 1 .3E-03 5 6 1.2 E-03 5 7 8 .5E -04 5 8 5 .1E-04 5 9 4 . 5 E - 0 4 5 1 0 3 .9E -04 511 3 .4E -04 5 1 2 3 .1E -04 5 1 3 3 .1E -04 5 1 4 3 .5E -04 5 1 5 3 .2E -04 5 1 6 3 . 3 E - 0 4 5 1 7 2 . 5 E - 0 4 5 1 8 2 . 9 E - 0 4 5 1 9 2 . 5 E - 0 4 5 2 0 2 . 5 E - 0 4 521 1 .9E-04 5 2 2 2 . 0 E - 0 4 5 2 3 1.9E-04 5 2 4 1.6E-04 {NH4 + } {P04~ } mol/L mol/L 2 . 1 E - 0 2 1.1E-10 2 . 0 E - 0 2 1.2E-10 1.8E-02 1.5E-10 2.1 E-02 1.8E-10 2 . 0 E - 0 2 2 . 2 E - 1 0 1 .9E-02 2 . 9 E - 1 0 1 .6E-02 5 .8E -10 1.7E-02 1 .3E-09 1.4E-02 1 .8E-09 2.1 E-02 3 . 1 E - 0 9 1.5E-02 2 . 7 E - 0 9 1.9E-02 3 .4E -09 2 . 0 E - 0 2 3 .5E -09 2 . 0 E - 0 2 4 . 3 E - 0 9 1.9E-02 4 . 7 E - 0 9 1.9E-02 4 . 2 E - 0 9 1.9E-02 4 . 8 E - 0 9 1.9E-02 5 .1E -09 1.8E-02 6 .0E -09 1.1 E-02 9 .7E -09 1.6E-02 7 .7E -09 1.6E-02 1 .OE-08 9 . 7 E - 0 3 1.6E-08 1.1 E-02 1.9E-08 P K S P 4 . 3 E - 1 5 14.4 4 . 8 E - 1 5 14.3 4 . 7 E - 1 5 14.3 5 . 1 E - 1 5 14.3 6 . 0 E - 1 5 14.2 6 . 1 E - 1 5 14.2 7 . 8 E - 1 5 14.1 1.1E-14 14.0 1.1E-14 14.0 2 . 6 E - 1 4 13.6 1.4E-14 13.9 2 . 1 E - 1 4 13.7 2 . 2 E - 1 4 13.7 3 .0E-14 13.5 2 .9E -14 13.5 2 . 7 E - 1 4 13.6 2 . 3 E - 1 4 13.6 2 .8E -14 13.5 2 .8E -14 13.6 2 . 6 E - 1 4 13.6 2 . 3 E - 1 4 13.6 3 .3E -14 13.5 2 . 8 E - 1 4 13.5 3 .2E -14 13.5 Ionic Strength 0.08 0.08 0.08 0.08 0.08 0.07 0.07 0.06 0.06 0.06 0.06 0 .05 0.06 0 .05 0 .05 0.06 0 .05 0 .05 0.06 0.06 0.06 0.06 0.06 0.06 104 A P P E N D I X B Solubi l i ty Tr ia ls Us ing Dist i l led W a t e r and Struvi te g rown in Pent ic ton p H Conduct iv i ty S a m p l e u S / c m D1 7.01 889 D 2 7.05 721 D 3 7.08 709 D4 7.1 798 D 5 7.26 551 D 6 7.33 598 D 7 7.34 576 D 8 7.41 4 8 0 D 9 7.42 466 D 1 0 7.45 426 D11 7.56 4 4 0 D 1 2 7.58 356 D 1 3 7.58 388 D 1 4 7.6 384 D 1 5 7.64 397 D 1 6 7.7 3 9 5 D 1 7 7.71 374 D 1 8 7.71 330 D 1 9 7.73 334 D 2 0 7.77 319 D21 7.82 264 D 2 2 7.98 2 2 5 D 2 3 8.03 2 3 5 D24 8.19 191 D 2 5 8.24 3 1 5 D 2 6 8.26 177 D 2 7 8.3 236 D 2 8 8 .35 3 5 3 D 2 9 8.41 160 D 3 0 8.51 158 D31 8.58 4 2 0 D 3 2 8.62 165 D 3 3 9 .15 227 D 3 4 9 .15 527 D 3 5 9.52 3 2 9 D 3 6 9.62 3 1 0 S a m p l e data M g N H 4 - N P 0 4 - P mg /L mg /L m g / L 81.6 48 .8 111.9 63 .0 37 .5 87.7 61 .9 36.2 81 .2 71 .3 42.1 98.4 52.6 28.2 74 .2 58.0 33 .0 77.4 51.8 29 .0 69 .0 43 .6 24 .3 61 .0 44 .9 23.1 59.7 42 .4 20.7 56.2 42.1 21.8 56.6 36.8 16.9 46 .9 39.1 17.7 53.4 34 .5 18.4 46 .0 38.7 18.0 51.6 36.6 19.0 46 .6 36 .2 17.9 46 .6 32.7 14.0 42 .0 30.7 15.9 39 .0 33.4 13.0 4 3 . 3 30 .0 12.0 38.8 22.8 10.2 29.1 25.6 9.1 32.1 20 .0 8.9 25 .2 26 .0 7.6 28.6 20 .0 8.5 24 .2 20.6 8.0 29 .0 25.8 7.6 37.7 17.7 7.7 22 .4 17.1 7.3 22 .2 19.6 6.8 37.1 13.7 8.2 22.1 7.8 9.4 17.8 9.9 7.2 35 .0 5.5 10.6 18.6 4.8 12.4 19.9 M g N H 4 - N PO4-P mo l /L mol /L mol /L 0 .00336 0 0 0 3 4 9 0 00361 0 .00259 0 00268 0 00283 0 .00255 0 0 0 2 5 8 0 00262 0 .00294 0 00301 0 00318 0 .00216 0 00201 0 00240 0 .00239 0 0 0 2 3 5 0 00250 0 .00213 0 00207 0 0 0 2 2 3 0 .00179 0 0 0 1 7 4 0 00197 0 .00185 0 0 0 1 6 5 0 0 0 1 9 3 0 .00175 0 00148 0 00181 0 .00173 0 0 0 1 5 6 0 0 0 1 8 3 0.00151 0 00121 0 00152 0.00161 0 0 0 1 2 6 0 00172 0 .00142 0 00131 0 00149 0 .00159 0 0 0 1 2 8 0 00167 0.00151 0 0 0 1 3 6 0 00151 0 .00149 0 0 0 1 2 8 0 00150 0 .00134 0 0 0 1 0 0 0 00136 0 .00126 0 00114 0 00126 0 .00137 0 0 0 0 9 3 0 00140 0 .00124 0 0 0 0 8 6 0 0 0 1 2 5 0 .00094 0 0 0 0 7 3 0 00094 0 .00105 0 0 0 0 6 5 0 00103 0 .00082 0 0 0 0 6 3 0 00081 0 .00107 0 0 0 0 5 5 0 00092 0 .00082 0 00061 0 00078 0 .00085 0 0 0 0 5 7 0 00094 0 .00106 0 0 0 0 5 5 0 00122 0 .00073 0 0 0 0 5 5 0 00072 0 .00070 0 00052 0 00072 0.00081 0 0 0 0 4 8 0 00120 0 .00056 0 0 0 0 5 9 0 00071 0 .00032 0 0 0 0 6 7 0 00057 0.00041 0 0 0 0 5 2 0 0 0 1 1 3 0 .00023 0 0 0 0 7 5 0 00060 0 .00020 0 00088 0 00064 105 A P P E N D I X B M g : P N : P Mo la r Mo la r Struvite amp le Rat io Rat io P s D1 0.9 1.0 4 . 2 E - 0 8 D 2 0.9 0.9 2 . 0 E - 0 8 D 3 1.0 1.0 1.7E-08 D4 0.9 0.9 2 . 8 E - 0 8 D 5 0.9 0.8 1 .OE-08 D 6 1.0 0.9 1 .4E-08 D 7 1.0 0.9 9 . 9 E - 0 9 D 8 0.9 0.9 6 . 1 E - 0 9 D9 1.0 0.9 5 .9E -09 D 1 0 1.0 0.8 4 . 7 E - 0 9 D11 0.9 0.9 4 . 9 E - 0 9 D 1 2 1.0 0.8 2 . 8 E - 0 9 D 1 3 0.9 0.7 3 .5E -09 D 1 4 1.0 0.9 2 . 8 E - 0 9 D 1 5 1.0 0.8 3 .4E -09 D 1 6 1.0 0.9 3 .1E -09 D 1 7 1.0 0.8 2 . 9 E - 0 9 D 1 8 1.0 0.7 1 .8E-09 D 1 9 1.0 0.9 1 .8E-09 D 2 0 1.0 0.7 1 .8E-09 D21 1.0 0.7 1 .3E-09 D 2 2 1.0 0.8 6 . 4 E - 1 0 D 2 3 1.0 0.6 7 .1E -10 D 2 4 1.0 0.8 4 . 2 E - 1 0 D 2 5 1.2 0.6 5 .4E -10 D 2 6 1.1 0.8 3 .9E -10 D 2 7 0.9 0.6 4 . 5 E - 1 0 D 2 8 0.9 0.4 7 .0E -10 D 2 9 1.0 0.8 2 . 9 E - 1 0 D 3 0 1.0 0.7 2 . 6 E - 1 0 D31 0.7 0.4 4 . 7 E - 1 0 D 3 2 0.8 0.8 2 . 4 E - 1 0 D 3 3 0.6 1.2 1.2E-10 D 3 4 0.4 0.5 2 . 4 E - 1 0 D 3 5 0.4 1.3 1.0E-10 D 3 6 0.3 1.4 1.1E-10 Struvite P h o s p h a t e D issoc ia t ion C o n s t a n t s P P s k a ! k a 2 k a 3 7.4 7.81 E -03 6 1 2 E - 0 8 5 E - 13 7.7 7.81 E -03 6 1 2 E - 0 8 5 E - 13 7.8 7.81 E-03 6 1 2 E - 0 8 5 E - 13 7.6 7.81 E-03 6 1 2 E - 0 8 5 E - 13 8.0 7.81 E-03 6 1 2 E - 0 8 5 E - 13 7.9 7.81 E-03 6 1 2 E - 0 8 5 E - 13 8.0 7.81 E-03 6 1 2 E - 0 8 5 E - 13 8.2 7.81 E-03 6 1 2 E - 0 8 5 E - 13 8.2 7.81 E-03 6 1 2 E - 0 8 5 E - 13 8.3 7.81 E-03 6 1 2 E - 0 8 5 E - 13 8.3 7.81 E-03 6 1 2 E - 0 8 5 E - 13 8.6 7.81 E-03 6 1 2 E - 0 8 5 E - 13 8.5 7.81 E-03 6 1 2 E - 0 8 5 E - 13 8.6 7.81 E-03 6 1 2 E - 0 8 5 E - 13 8.5 7.81 E-03 6 1 2 E - 0 8 5 E - 13 8.5 7.81 E-03 6 1 2 E - 0 8 5 E - 13 8.5 7.81 E-03 6 1 2 E - 0 8 5 E - 13 8.7 7.81 E-03 6 1 2 E - 0 8 5 E - 13 8.7 7.81 E-03 6 1 2 E - 0 8 5 E - 13 8.7 7.81 E-03 6 1 2 E - 0 8 5 E - 13 8.9 7.81 E-03 6 1 2 E - 0 8 5 E - 13 9.2 7.81 E-03 6 1 2 E - 0 8 5 E - 13 9.1 7.81 E-03 6 1 2 E - 0 8 5 E - 13 9.4 7.81 E-03 6 1 2 E - 0 8 5 E - 13 9.3 7.81 E-03 6 1 2 E - 0 8 5 E - 13 9.4 7.81 E-03 6 1 2 E - 0 8 5 E - 13 9.3 7.81 E-03 6 1 2 E - 0 8 5 E - 13 9.2 7.81 E -03 6 1 2 E - 0 8 5 E - 13 9.5 7.81 E -03 6 1 2 E - 0 8 5 E - 13 9.6 7.81 E -03 6 1 2 E - 0 8 5 E - 13 9.3 7.81 E -03 6 1 2 E - 0 8 5 E - 13 9.6 7.81 E -03 6 1 2 E - 0 8 5 E - 13 9.9 7.81 E -03 6 1 2 E - 0 8 5 E - 13 9.6 7.81 E -03 6 1 2 E - 0 8 5 E - 13 10.0 7.81 E -03 6 1 2 E - 0 8 5 E - 13 9.9 7.81 E -03 6 1 2 E - 0 8 5 E - 13 106 A P P E N D I X B A m m o n i a S a m p l e k a D1 6 . 0 5 E - 1 0 D2 6 . 0 5 E - 1 0 D 3 6 . 0 5 E - 1 0 D4 6 . 0 5 E - 1 0 D 5 6 . 0 5 E - 1 0 D 6 6 . 0 5 E - 1 0 D 7 6 . 0 5 E - 1 0 D 8 6 . 0 5 E - 1 0 D 9 6 . 0 5 E - 1 0 D 1 0 6 . 0 5 E - 1 0 D11 6 . 0 5 E - 1 0 D 1 2 6 . 0 5 E - 1 0 D 1 3 6 . 0 5 E - 1 0 D 1 4 6 . 0 5 E - 1 0 D 1 5 6 . 0 5 E - 1 0 D 1 6 6 . 0 5 E - 1 0 D 1 7 6 . 0 5 E - 1 0 D 1 8 6 . 0 5 E - 1 0 D 1 9 6 . 0 5 E - 1 0 D 2 0 6 . 0 5 E - 1 0 D21 6 . 0 5 E - 1 0 D 2 2 6 . 0 5 E - 1 0 D 2 3 6 . 0 5 E - 1 0 D 2 4 6 . 0 5 E - 1 0 D 2 5 6 . 0 5 E - 1 0 D26 6 . 0 5 E - 1 0 D 2 7 6 . 0 5 E - 1 0 D 2 8 6 . 0 5 E - 1 0 D 2 9 6 . 0 5 E - 1 0 D 3 0 6 . 0 5 E - 1 0 D31 6 . 0 5 E - 1 0 D 3 2 6 . 0 5 E - 1 0 D 3 3 6 . 0 5 E - 1 0 D34 6 . 0 5 E - 1 0 D 3 5 6 . 0 5 E - 1 0 D36 6 . 0 5 E - 1 0 M g O H [H +] kb mol /L 2 . 7 5 E - 0 3 9 . 8 E - 0 8 2 . 7 5 E - 0 3 8 . 9 E - 0 8 2 . 7 5 E - 0 3 8 .3E -08 2 . 7 5 E - 0 3 7 .9E-08 2 . 7 5 E - 0 3 5 .5E -08 2 . 7 5 E - 0 3 4 . 7 E - 0 8 2 . 7 5 E - 0 3 4 . 6 E - 0 8 2 . 7 5 E - 0 3 3 .9E -08 2 . 7 5 E - 0 3 3 .8E -08 2 . 7 5 E - 0 3 3 . 5 E - 0 8 2 . 7 5 E - 0 3 2 . 8 E - 0 8 2 . 7 5 E - 0 3 2 . 6 E - 0 8 2 . 7 5 E - 0 3 2 . 6 E - 0 8 2 . 7 5 E - 0 3 2 . 5 E - 0 8 2 . 7 5 E - 0 3 2 . 3 E - 0 8 2 . 7 5 E - 0 3 2 . 0 E - 0 8 2 . 7 5 E - 0 3 1.9E-08 2 . 7 5 E - 0 3 1.9E-08 2 . 7 5 E - 0 3 1.9E-08 2 . 7 5 E - 0 3 1.7E-08 2 . 7 5 E - 0 3 1.5E-08 2 . 7 5 E - 0 3 1 .OE-08 2 . 7 5 E - 0 3 9 . 3 E - 0 9 2 . 7 5 E - 0 3 6 . 5 E - 0 9 2 . 7 5 E - 0 3 5 .8E -09 2 . 7 5 E - 0 3 5 .5E -09 2 . 7 5 E - 0 3 5 .0E -09 2 . 7 5 E - 0 3 4 . 5 E - 0 9 2 . 7 5 E - 0 3 3 .9E -09 2 . 7 5 E - 0 3 3 .1E -09 2 . 7 5 E - 0 3 2 . 6 E - 0 9 2 . 7 5 E - 0 3 2 4 E - 0 9 2 . 7 5 E - 0 3 7 .1E -10 2 . 7 5 E - 0 3 7 .1E -10 2 . 7 5 E - 0 3 3 .0E -10 2 . 7 5 E - 0 3 2 . 4 E - 1 0 [OH1 [Mg + + ] mo l /L mo l /L 1 .OE-07 3 . 4 E - 0 3 1.1E-07 2 . 6 E - 0 3 1.2E-07 2 . 5 E - 0 3 1 .3E-07 2 . 9 E - 0 3 1 .8E-07 2 . 2 E - 0 3 2 . 1 E - 0 7 2 . 4 E - 0 3 2 . 2 E - 0 7 2.1 E -03 2 . 6 E - 0 7 1 .8E-03 2 . 6 E - 0 7 1 .8E-03 2 . 8 E - 0 7 1 .7E-03 3 .6E -07 1 .7E-03 3 .8E -07 1 .5E-03 3 .8E -07 1 .6E-03 4 . 0 E - 0 7 1 .4E-03 4 . 4 E - 0 7 1 .6E-03 5 .0E -07 1 .5E-03 5 .1E -07 1 .5E-03 5 .1E -07 1 .3E-03 5 .4E -07 1 .3E-03 5 .9E -07 1 .4E-03 6 .6E -07 1 .2E-03 9 .5E -07 9 . 4 E - 0 4 1.1E-06 1.1 E -03 1.5E-06 8 . 2 E - 0 4 1.7E-06 1.1 E -03 1.8E-06 8 . 2 E - 0 4 2 . 0 E - 0 6 8 . 5 E - 0 4 2 . 2 E - 0 6 1.1 E -03 2 . 6 E - 0 6 7 .3E -04 3 . 2 E - 0 6 7 .0E -04 3 .8E -06 8 . 1 E - 0 4 4 . 2 E - 0 6 5 .6E -04 1 .4E-05 3 . 2 E - 0 4 1 .4E-05 4 . 1 E - 0 4 3 . 3 E - 0 5 2 . 2 E - 0 4 4 . 2 E - 0 5 2 . 0 E - 0 4 [NH4 + ] [ P 0 4 ~ ] mo l /L mol /L 3 . 5 E - 0 3 7 .1E-09 2 . 7 E - 0 3 6 .5E -09 2 . 6 E - 0 3 6 .7E-09 3 . 0 E - 0 3 8 .7E-09 2 . 0 E - 0 3 1.1E-08 2 . 3 E - 0 3 1.5E-08 2 . 0 E - 0 3 1.4E-08 1 .7E-03 1.5E-08 1 .6E-03 1.6E-08 1 .5E-03 1.6E-08 1 .5E-03 2 . 3 E - 0 8 1 .2E-03 2 . 0 E - 0 8 1 .2E-03 2 . 3 E - 0 8 1 .3E-03 2 . 1 E - 0 8 1 .3E-03 2 . 6 E - 0 8 1 .3E-03 2 . 8 E - 0 8 1.2 E -03 2 . 9 E - 0 8 9 .7E -04 2 . 6 E - 0 8 1.1 E -03 2 . 6 E - 0 8 9 .0E -04 3 .2E-08 8 . 3 E - 0 4 3 .3E-08 6 . 9 E - 0 4 3 .8E-08 6 .1E -04 4 . 8 E - 0 8 5 .8E -04 5 .7E-08 4 . 9 E - 0 4 7 .3E-08 5 .5E-04 6 .5E-08 5 .1E-04 8 .6E-08 4 . 8 E - 0 4 1.3E-07 4 . 7 E - 0 4 8 .7E -08 4 . 3 E - 0 4 1.1E-07 3 .9E -04 2 . 2 E - 0 7 4 . 7 E - 0 4 1.4E-07 3 .6E -04 4 . 0 E - 0 7 2 . 8 E - 0 4 7 .9E-07 2 . 5 E - 0 4 9 .9E-07 2 . 5 E - 0 4 1.3E-06 107 {Mg + + } S a m p l e mol /L D1 2.1 E-03 D2 1 .7E-03 D 3 1 .6E-03 D4 1 .8E-03 D 5 1 .5E-03 D6 1 .6E-03 D7 1 .4E-03 D 8 1 .2E-03 D 9 1 .3E-03 D 1 0 1 .2E-03 D11 1 .2E-03 D 1 2 1.1 E-03 D 1 3 1.1 E-03 D 1 4 1 .OE-03 D 1 5 1.1 E-03 D 1 6 1.1 E-03 D 1 7 1.1 E-03 D 1 8 9 .8E -04 D 1 9 9 .2E -04 D 2 0 1 .OE-03 D21 9 .3E -04 D 2 2 7 .2E -04 D 2 3 8 .1E -04 D 2 4 6 .5E -04 D 2 5 7 .9E -04 D 2 6 6 .5E -04 D27 6 .5E -04 D 2 8 7 .7E -04 D 2 9 5 .8E -04 D 3 0 5 .6E-04 D31 5 .7E-04 D 3 2 4 . 5 E - 0 4 D 3 3 2 . 4 E - 0 4 D 3 4 2 . 8 E - 0 4 D 3 5 1.6E-04 D 3 6 1.5E-04 {NH4 + } { P 0 4 ~ } mol /L mol /L 3.1 E -03 2 . 4 E - 0 9 2 . 4 E - 0 3 2 . 4 E - 0 9 2 . 3 E - 0 3 2 . 5 E - 0 9 2 . 7 E - 0 3 3 .0E -09 1.8E-03 4 . 7 E - 0 9 2.1 E-03 6 . 0 E - 0 9 1.9E-03 5 .6E -09 1.6E-03 6 . 7 E - 0 9 1.5E-03 6 . 9 E - 0 9 1.3E-03 7 .3E -09 1 .4E-03 1.0E-08 1.1 E-03 9 . 7 E - 0 9 1.1 E-03 1.1E-08 1.2E-03 9 . 9 E - 0 9 1.1 E-03 1.2E-08 1.2E-03 1.3E-08 1.1 E-03 1.4E-08 9 .0E-04 1.3E-08 1 .OE-03 1.3E-08 8 .3E -04 1.6E-08 7 .7E-04 1.8E-08 6 .5E -04 2 . 1 E - 0 8 5 .7E-04 2 . 6 E - 0 8 5 .5E-04 3 . 3 E - 0 8 4 . 6 E - 0 4 3 .7E -08 5 .1E-04 3 . 9 E - 0 8 4 . 8 E - 0 4 4 . 7 E - 0 8 4 . 4 E - 0 4 6 . 2 E - 0 8 4 . 5 E - 0 4 5 .3E -08 4 . 1 E - 0 4 6 . 7 E - 0 8 3 .6E -04 9 . 9 E - 0 8 4 . 4 E - 0 4 8 .6E -08 3 .4E -04 2 . 2 E - 0 7 2 . 5 E - 0 4 3 .3E -07 2 . 3 E - 0 4 4 . 9 E - 0 7 2 . 3 E - 0 4 6 .7E -07 K s p p K s p 1.5E- 14 13.8 9 .4E- 15 14.0 9 .3E- 15 14.0 1.5E- 14 13.8 1.2E- 14 13.9 2 .0E- 14 13.7 1.5E- 14 13.8 1.3E- 14 13.9 1.3E- 14 13.9 1.2E- 14 13.9 1.7E- 14 13.8 1.2E- 14 13.9 1.4E- 14 13.9 1.2E- 14 13.9 1.6E- 14 13.8 1.7E- 14 13.8 1.7E- 14 13.8 1.2E- 14 13.9 1.2E- 14 13.9 1.4E- 14 13.9 1.3E- 14 13.9 9 .9E- 15 14.0 1.2E- 14 13.9 1.2E- 14 13.9 1.3E- 14 13.9 1.3E- 14 13.9 1.5E- 14 13.8 2 .1E- 14 13.7 1.4E- 14 13.9 1.6E- 14 13.8 2 .0E- 14 13.7 1.7E- 14 13.8 1.8E- 14 13.7 2 .3E- 14 13.6 1.9E- 14 13.7 2 .3E- 14 13.6 Ionic St rength 0 .014 0 .012 0.011 0 .013 0 .009 0.010 0.009 0.008 0.007 0.007 0.007 0.006 0.006 0 .006 0 .006 0 .006 0 .006 0 .005 0 .005 0 .005 0 .004 0 .004 0 .004 0 .003 0 .005 0 .003 0 .004 0 .006 0 .003 0 .003 0 .007 0 .003 0.004 0.008 0 .005 0 .005 A P P E N D I X C APPENDIX C: OPERATING DATA FOR REACTOR A 109 A P P E N D I X C Date MgCl Feed Supernatant Lab results Effluent Lab results pH Mg PO4-P NH4.N Mg PO4-P NH 4 .N Mg (mg/1) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) 2-Sep-01 1092 9.4 263 28.0 7.7 220 79.0 8.3 4-Sep-01 1092 8.3 284 27.3 11.3 263 83.0 8.4 5-Sep-01 1092 8.0 270 41.9 7.6 220 81.0 8.3 13-Sep-01 714 10.2 273 16.7 7.5 267 59.2 8.9 14-Sep-01 714 10.5 283 16.2 7.7 272 49.0 8.9 15-Sep-01 986 10.8 271 14.9 7.1 254 63.2 8.9 16-Sep-01 986 12.1 314 16.9 8.6 253 57.6 8.8 17-Sep-01 986 12.1 282 15.7 12.2 263 79.2 8.1 18-Sep-01 986 11.9 298 16.0 9.7 255 67.0 8.2 19-Sep-01 986 13.7 272 16.1 8.1 246 64.4 8.6 20-Sep-01 986 11.7 277 14.4 8.2 278 71.8 8.5 21-Sep-01 977 11.5 277 13.5 8.3 272 79.0 8.8 22-Sep-01 977 12.8 279 11.7 8.9 259 30.8 8.8 23-Sep-01 977 12.6 281 16.4 8.8 260 71.0 8.8 24-Sep-01 977 12.3 276 13.4 18.0 232 110.4 8.8 2-Oct-01 977 12.3 290 21.1 5.5 279 102.4 8.8 3-Oct-01 977 11.8 262 21.4 3.9 237 79.1 8.8 4-Oct-01 977 18.8 270 29.2 12.0 245 48.0 8.6 5-Oct-01 792 18.0 260 29.7 12.8 210 49.7 8.6 10-Oct-01 792 17.8 265 28.8 7.1 235 52.9 8.8 11-Oct-01 792 43.4 252 30.3 16.5 236 50.6 8.7 12-Oct-01 792 44.3 314 11.1 10.4 239 69.5 8.2 13-Oct-01 792 42.3 279 14.8 10.1 257 41.7 8.5 14-Oct-OI 792 43.5 282 14.1 8.3 255 44.8 8.5 15-Oct-01 792 46.2 285 35.1 13.0 263 39.8 8.4 16-Oct-01 792 44.9 295 34.3 8.3 259 38.8 8.4 17-Oct-OI 792 45.8 299 28.3 12.4 270 27.1 8.2 18-Oct-01 792 48.7 284 29.3 11.2 306 28.2 8.5 24-Oct-01 792 44.5 290 18.9 17.7 283 14.7 8.5 25-Oct-01 657 43.9 302 21.1 8.9 254 32.3 8.6 26-Oct-01 657 37.2 289 24.3 4.8 230 31.7 8.6 27-Oct-01 657 42.9 293 26.3 7.1 249 36.6 8.4 28-Oct-01 657 40.4 245 29.1 8.5 207 31.4 8.5 29-Oct-01 657 40.1 293 24.7 6.1 251 33.4 8.4 30-Oct-01 657 39.9 293 21.7 6.2 235 35.1 8.4 31-Oct-01 733 45.6 295 23.4 10.8 258 31.5 8.3 110 A P P E N D I X C Date M g C l Caustic Total Supernatant Recycle Total flow Flow Flow Influent Flow Flow Flow (influent+recycle) (mL/min) (1/day) (mL/min) (mL/min) (mL/min) (mL/min) 2-Sep-01 47 103.5 950 831 2850 3800 4-Sep-01 52 100 900 779 2750 3650 5-Sep-01 47 75 950 851 2750 3700 13-Sep-01 48 10 1075 1020 2625 3700 14-Sep-01 46 7.5 1050 999 2600 3650 15-Sep-01 49 5 1000 948 2600 3600 16-Sep-01 60 7.5 1200 1135 2650 3850 17-Sep-01 62 80 1050 932 2650 3700 18-Sep-01 49 115 1000 871 2600 3600 19-Sep-01 52 150 925 769 2625 3550 20-Sep-01 50 5 950 897 2650 3600 21-Sep-01 50 7.5 1100 1045 2550 3650 22-Sep-01 0 2.5 1225 1223 2475 3700 23-Sep-01 51 15 1200 1139 2500 3700 24-Sep-01 52 5 1200 1145 2500 3700 2-Oct-01 52 15 1075 1013 2525 3600 3-Oct-01 52 20 1000 934 2500 3500 4-Oct-01 0 75 1350 1298 2500 3850 5-Oct-01 52 57.5 1325 1233 2425 3750 10-Oct-01 54 5 1125 1068 2525 3650 11-Oct-01 54 50 1225 1136 2525 3750 12-Oct-01 52 15 712 650 2938 3650 13-Oct-01 30 15 730 690 2820 3550 14-Oct-01 30 12.5 610 571 2940 3550 15-Oct-01 30 20 810 766 2940 3750 16-Oct-01 31 17.5 720 677 2830 3550 17-Oct-01 18 20 710 678 2865 3575 18-Oct-01 19 17.5 700 669 2900 3600 24-Oct-01 0 17.5 770 758 2880 3650 25-Oct-01 50 15 780 720 2820 3600 26-Oct-01 52 30 740 667 2860 3600 27-Oct-01 52 17.5 710 646 2890 3600 28-Oct-01 51 22.5 700 633 2900 3600 29-Oct-01 52 50 770 683 2830 3600 30-Oct-01 54 42.5 750 666 2825 3575 31-Oct-01 42 95 780 672 2870 3650 111 A P P E N D I X C Date Conditions at the inlet Removal efficiency (%) PO4_P N H 4 - N M g P04-P N H 4 . N M g (mg/L) (mg/L) (mg/L) 2-Sep-01 8.2 230 78.5 6 4 -1 4-Sep-01 7.1 246 86.7 -59 -7 4 5-Sep-01 7.1 242 91.6 -6 9 12 13-Sep-01 9.7 259 47.7 23 -3 -24 14-Sep-01 10.0 269 46.7 23 -1 -5 15-Sep-01 10.2 257 62.4 31 1 -1 16-Sep-01 11.4 297 65.3 25 15 12 17-Sep-01 10.7 250 72.1 -14 -5 -10 18-Sep-01 10.4 260 62.2 6 2 -8 19-Sep-01 11.4 226 68.8 29 -9 6 20-Sep-01 11.0 261 65.5 26 -6 -10 21-Sep-01 10.9 263 57.2 24 -3 -38 22-Sep-01 12.8 279 11.7 30 7 -164 23-Sep-01 12.0 267 57.0 26 2 -25 24-Sep-01 11.7 263 55.1 -53 12 -100 2-Oct-01 11.6 273 67.1 53 -2 -53 3-Oct-01 11.0 245 70.8 65 3 -12 4-Oct-01 18.1 260 28.1 34 6 -71 5-Oct-01 16.8 242 58.7 24 13 15 10-Oct-01 16.9 251 65.3 58 7 19 11-Oct-01 40.3 234 63.0 59 -1 20 12-Oct-01 40.4 286 67.9 74 17 -2 13-Oct-01 40.0 264 46.5 75 2 10 14-Oct-01 40.7 264 52.2 80 3 14 15-Oct-01 43.7 270 62.5 70 2 36 16-Oct-01 42.2 277 66.3 80 7 42 17-Oct-01 43.7 286 47.1 72 5 43 18-Oct-01 46.5 271 49.5 76 -13 43 24-Oct-01 43.8 285 18.6 60 1 21 25-Oct-01 40.5 279 61.6 78 9 48 26-Oct-01 33.5 261 68.1 86 12 53 27-Oct-01 39.0 267 72.1 82 7 49 28-Oct-01 36.6 222 74.2 77 7 58 29-Oct-01 35.6 260 66.3 83 3 50 30-Oct-01 35.5 260 66.6 83 10 47 31-Oct-01 39.3 254 59.6 73 -2 47 112 A P P E N D I X C Date Molar removal M g : P N:P Inlet to outlet Removal Removal P 0 4 _ P N H 4 - N M g Ratio Ratio 2-Sep-01 1.6E-05 7.2E-04 -2.0E-05 -1.2 44.1 4-Sep-01 -1.4E-04 -1.2E-03 1.5E-04 -1.1 9.1 5-Sep-01 -1.3E-05 1.6E-03 4.4E-04 -32.7 -117.2 13-Sep-01 7.0E-05 -5.7E-04 -4.7E-04 -6.7 -8.1 14-Sep-01 7.4E-05 -2.0E-04 -9.5E-05 -1.3 -2.7 15-Sep-01 1.0E-04 2.0E-04 -3.6E-05 -0.4 2.0 16-Sep-01 9.2E-05 3.1 E-03 3.2E-04 3.4 34.2 17-Sep-01 -4.7E-05 -9.0E-04 -2.9E-04 6.2 19.1 18-Sep-01 2.2E-05 3.3E-04 -2.0E-04 -9.1 15.3 19-Sep-01 1.1E-04 -1.4E-03 1.8E-04 1.7 -13.4 20-Sep-01 9.2E-05 -1.2E-03 -2.6E-04 -2.8 -12.9 21-Sep-01 8.5E-05 -6.4E-04 -9.0E-04 -10.6 -7.5 22-Sep-01 1.3E-04 1.4E-03 -7.9E-04 -6.3 11.2 23-Sep-01 1.0E-04 4.7E-04 -5.8E-04 -5.7 4.6 24-Sep-01 -2.0E-04 2.2E-03 -2.3E-03 11.2 -11.0 2-Oct-01 2.0E-04 -4.2E-04 -1.5E-03 -7.4 -2.1 3-Oct-01 2.3E-04 5.5E-04 -3.4E-04 -1.5 2.4 4-Oct-01 2.0E-04 1.0E-03 -8.2E-04 -4.2 5.3 5-Oct-01 1.3E-04 2.3E-03 3.7E-04 2.9 17.9 10-Oct-01 3.2E-04 1.2E-03 5.1E-04 1.6 3.7 11-Oct-01 7.7E-04 -1.6E-04 5.1E-04 0.7 -0.2 12-Oct-OI 9.7E-04 3.4E-03 -6.3E-05 -0.1 3.5 13-Oct-OI 9.6E-04 4.7E-04 2.0E-04 0.2 0.5 14-Oct-01 1 .OE-03 6.5E-04 3.0E-04 0.3 0.6 15-Oct-OI 9.9E-04 4.7E-04 9.3E-04 0.9 0.5 16-Oct-01 1.1 E-03 1.3E-03 1.1 E-03 1.0 1.2 17-Oct-01 1.OE-03 1.1 E-03 8.2E-04 0.8 1.1 18-Oct-01 1.1 E-03 -2.5E-03 8.8E-04 0.8 -2.2 24-Oct-01 8.4E-04 1.7E-04 1.6E-04 0.2 0.2 25-Oct-01 1.OE-03 1.8E-03 1.2E-03 1.2 1.7 26-Oct-01 9.3E-04 2.2E-03 1.5E-03 1.6 2.4 27-Oct-01 1 .OE-03 1.3E-03 1.5E-03 1.4 1.2 28-Oct-01 9.1E-04 1.OE-03 1.8E-03 1.9 1.2 29-Oct-01 9.5E-04 6.4E-04 1.4E-03 1.4 0.7 30-Oct-01 9.4E-04 1.8E-03 1.3E-03 1.4 1.9 31-Oct-01 9.2E-04 -2.7E-04 1.2E-03 1.3 -0.3 113 A P P E N D I X C Date PO4-P In-Reactor N H 4 - N In-Reactor Feed gives Recycle gives Total Feed gives Recycle gives Total (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) 2-Sep-01 2.1 5.8 7.8 58 165 223 4-Sep-01 1.8 8.5 10.3 61 198 259 5-Sep-01 1.8 5.6 7.5 62 164 226 13-Sep-01 2.8 5.3 8.1 75 189 265 14-Sep-01 2.9 5.5 8.4 77 194 271 15-Sep-01 2.8 5.1 8.0 71 183 255 16-Sep-01 3.6 5.9 9.5 93 174 267 17-Sep-01 3.0 8.7 11.8 71 188 259 18-Sep-01 2.9 7.0 9.9 72 184 256 19-Sep-01 3.0 6.0 9.0 59 182 241 20-Sep-01 2.9 6.0 8.9 69 205 274 21-Sep-01 3.3 5.8 9.1 79 190 269 22-Sep-01 4.2 6.0 10.2 92 173 265 23-Sep-01 3.9 5.9 9.8 86 176 262 24-Sep-01 3.8 12.2 16.0 85 157 242 2-Oct-01 3.5 3.9 7.3 82 196 277 3-Oct-01 3.1 2.8 5.9 70 169 239 4-Oct-01 6.3 7.8 14.1 91 159 250 5-Oct-01 5.9 8.3 14.2 85 136 221 10-Oct-01 5.2 4.9 10.1 78 163 240 11-Oct-01 13.2 11.1 24.3 76 159 235 12-Oct-01 7.9 8.4 16.3 56 192 248 13-Oct-01 8.2 8.0 16.2 54 204 258 14-Oct-01 7.0 6.9 13.9 45 211 257 15-Oct-01 9.4 10.2 19.6 58 206 264 16-Oct-01 8.6 6.6 15.2 56 206 263 17-Oct-01 8.7 9.9 18.6 57 216 273 18-Oct-01 9.0 9.0 18.1 53 247 299 24-Oct-01 9.2 14.0 23.2 60 223 284 25-Oct-01 8.8 7.0 15.7 60 199 259 26-Oct-01 6.9 3.8 10.7 54 183 236 27-Oct-01 7.7 5.7 13.4 53 200 252 28-Oct-01 7.1 6.8 14.0 43 167 210 29-Oct-01 7.6 4.8 12.4 56 197 253 30-Oct-01 7.4 4.9 12.3 55 186 240 31-Oct-01 8.4 8.5 16.9 54 203 257 114 Date M g In-Reactor In-Reactor Concentrations In-Reacor M g : P In-Reactor N:P Feed gives Recycle gives Total P 0 4 _ P N H 4 - N M g (molar ratio) (molar ratio) (mg/L) (mg/L) (mg/L) (mol/L) (mol/L) (mol/L) 2-Sep-01 19.6 59.3 78.9 2.5E-04 1.6E-02 3.2E-03 12.8 62.9 4-Sep-01 21.4 62.5 83.9 3.3E-04 1.8E-02 3.5E-03 10.4 55.5 5-Sep-01 23.5 60.2 83.7 2.4E-04 1.6E-02 3.4E-03 14.3 67.0 13-Sep-01 13.9 42.0 55.9 2.6E-04 1.9E-02 2.3E-03 8.8 72.0 14-Sep-01 13.4 34.9 48.3 2.7E-04 1.9E-02 2.0E-03 7.4 71.8 15-Sep-01 17.3 45.7 63.0 2.6E-04 1.8E-02 2.6E-03 10.1 70.7 16-Sep-01 20.3 39.6 60.0 3.1E-04 1.9E-02 2.5E-03 8.1 62.2 17-Sep-01 20.5 56.7 77.2 3.8E-04 1.9E-02 3.2E-03 8.3 48.7 18-Sep-01 17.3 48.4 65.7 3.2E-04 1.8E-02 2.7E-03 8.5 57.4 19-Sep-01 17.9 47.6 65.5 2.9E-04 1.7E-02 2.7E-03 9.3 59.5 20-Sep-01 17.3 52.9 70.1 2.9E-04 2.0E-02 2.9E-03 10.0 67.6 21-Sep-01 17.2 55.2 72.4 2.9E-04 1.9E-02 3.0E-03 10.1 65.5 22-Sep-01 3.9 20.6 24.5 3.3E-04 1.9E-02 1.0E-03 3.1 57.7 23-Sep-01 18.5 48.0 66.5 3.2E-04 1.9E-02 2.7E-03 8.6 59.0 24-Sep-01 17.9 74.6 92.5 5.2E-04 1.7E-02 3.8E-03 7.4 33.5 2-Oct-01 20.0 71.8 91.9 2.4E-04 2.0E-02 3.8E-03 16.0 83.8 3-Oct-01 20.2 56.5 76.8 1.9E-04 1.7E-02 3.2E-03 16.5 89.2 4-Oct-01 9.9 31.2 41.0 4.6E-04 1.8E-02 1.7E-03 3.7 39.2 5-Oct-01 20.7 32.1 52.9 4.6E-04 1.6E-02 2.2E-03 4.7 34.5 10-Oct-01 20.1 36.6 56.7 3.3E-04 1.7E-02 2.3E-03 7.1 52.5 11-Oct-01 20.6 34.1 54.7 7.8E-04 1.7E-02 2.3E-03 2.9 21.5 12-Oct-01 13.3 55.9 69.2 5.2E-04 1.8E-02 2.8E-03 5.4 33.8 13-Oct-01 9.6 33.1 42.7 5.2E-04 1.8E-02 1.8E-03 3.3 35.2 14-Oct-01 9.0 37.1 46.1 4.5E-04 1.8E-02 1.9E-03 4.2 40.9 15-Oct-01 13.5 31.2 44.7 6.3E-04 1.9E-02 1.8E-03 2.9 29.8 16-Oct-01 13.5 30.9 44.4 4.9E-04 1.9E-02 1.8E-03 3.7 38.3 17-Oct-01 9.4 21.7 31.0 6.0E-04 2.0E-02 1.3E-03 2.1 32.4 18-Oct-01 9.6 22.7 32.3 5.8E-04 2.1 E-02 1.3E-03 2.3 36.6 24-Oct-01 3.9 11.6 15.5 7.5E-04 2.0E-02 . 6.4E-04 0.9 27.0 25-Oct-01 13.3 25.3 38.6 5.1E-04 1.9E-02 1.6E-03 3.1 36.4 26-Oct-01 14.0 25.2 39.2 3.5E-04 1.7E-02 1.6E-03 4.7 48.8 27-Oct-01 14.2 29.4 43.6 4.3E-04 1.8E-02 1.8E-03 4.1 41.7 28-Oct-01 14.4 25.3 39.7 4.5E-04 1.5E-02 1.6E-03 3.6 33.3 29-Oct-01 14.2 26.3 40.4 4.0E-04 1.8E-02 1.7E-03 4.2 45.1 30-Oct-01 14.0 27.7 41.7 4.0E-04 1.7E-02 1.7E-03 4.3 43.1 31-Oct-01 12.7 24.8 37.5 5.5E-04 1.8E-02 1.5E-03 2.8 33.7 A P P E N D I X C Date Feed P s In-Reactor P s Equil ibrium P s Feed In-Reactor Effluent Crystal Harvest S.S. ratio S.S. Ratio S.S. Ratio Volume Volume (1) (1) 2-Sep-01 1.4E-08 1.3E-08 6.7E-09 2.1 1.9 1.9 4-Sep-01 1.4E-08 2.1E-08 5.7E-09 2.5 3.7 4.1 5-Sep-01 1.5E-08 1.3E-08 6.7E-09 2.2 2.0 1.9 13-Sep-01 1.1E-08 1.1E-08 3.0E-09 3.8 3.9 3.8 0.68 14-Sep-01 1.2E-08 1.0E-08 3.0E-09 4.0 3.5 3.3 0.75 15-Sep-01 1.6E-08 1.2E-08 3.0E-09 5.2 4.1 3.7 1.08 16-Sep-01 2.1E-08 1.4E-08 3.3E-09 6.3 4.3 3.6 1.40 17-Sep-01 1.8E-08 2.2E-08 9.5E-09 1.9 2.4 2.5 1.10 18-Sep-01 1.6E-08 1.6E-08 8.0E-09 2.0 2.0 2.0 1.20 19-Sep-01 1.7E-08 1.3E-08 4.3E-09 3.9 3.1 2.8 1.30 20-Sep-01 1.8E-08 1.6E-08 4.9E-09 3.6 3.3 3.2 1.40 21-Sep-01 1.6E-08 1.7E-08 3.3E-09 4.7 5.1 5.1 1.25 22-Sep-01 3.9E-09 6.3E-09 3.3E-09 1.2 1.9 2.0 1.20 23-Sep-01 1.7E-08 1.6E-08 3.3E-09 5.2 4.9 4.6 1.70 24-Sep-01 1.6E-08 3.4E-08 3.3E-09 4.9 10.2 13.2 1.20 2-Oct-01 2.0E-08 1.8E-08 3.3E-09 6.1 5.3 4.5 1.20 3-Oct-01 1.8E-08 1.0E-08 3.3E-09 5.5 3.1 2.1 1.50 4-Oct-01 1.3E-08 1.4E-08 4.3E-09 2.9 3.2 3.1 2.00 5-Oct-01 2.3E-08 1.6E-08 4.3E-09 5.3 3.7 3.0 2.55 10-Oct-01 2.6E-08 1.3E-08 3.3E-09 7.9 3.9 2.5 1.80 11-Oct-01 5.6E-08 3.0E-08 3.8E-09 15.0 7.9 5.0 3.30 12-Oct-01 7.5E-08 2.6E-08 8.0E-09 9.4 3.3 2.1 3.92 13-Oct-01 4.6E-08 1.7E-08 4.9E-09 9.4 3.4 2.1 3.84 14-Oct-01 5.3E-08 1.6E-08 4.9E-09 10.8 3.2 1.8 4.46 15-Oct-01 7.0E-08 2.2E-08 5.7E-09 12.2 3.8 2.3 5.08 16-Oct-01 7.4E-08 1.7E-08 5.7E-09 12.9 2.9 1.4 5.70 17-Oct-01 5.6E-08 1.5E-08 8.0E-09 7.0 1.9 1.1 5.10 18-Oct-01 5.9E-08 1.7E-08 4.9E-09 12.0 3.4 1.9 4.60 24-Oct-01 2.2E-08 9.7E-09 4.9E-09 4.5 2.0 1.4 5.20 25-Oct-01 6.6E-08 1.5E-08 4.3E-09 15.4 3.5 1.6 6.00 26-Oct-01 5.6E-08 9.4E-09 4.3E-09 13.2 2.2 0.8 6.90 27-Oct-01 7.1E-08 1.4E-08 5.7E-09 12.4 2.4 1.1 6.10 28-Oct-01 5.7E-08 1.1E-08 4.9E-09 11.6 2.2 1.1 6.50 29-Oct-01 5.8E-08 1.2E-08 5.7E-09 10.2 2.1 0.8 6.00 30-Oct-01 5.8E-08 1.2E-08 5.7E-09 10.2 2.0 0.8 6.40 31-Oct-01 5.7E-08 1.5E-08 6.7E-09 8.4 2.3 1.2 6.10 116 A P P E N D I X C Date C R T C R T Averaged Harvested Product Data Actual In reactor > 2 mm > 1 mm > 0.5 mm < 0.5 mm Total Mass (days) SS Ratio (g) (g) (g) (g) (g) 2-Sep-01 4- Sep-01 5- Sep-01 13- Sep-01 14- Sep-01 15- Sep-01 16- Sep-01 17- Sep-01 18- Sep-01 19- Sep-01 20- Sep-01 21- Sep-01 22- Sep-01 23- Sep-01 24- Sep-01 2- Oct-01 3- Oct-01 4- Oct-01 5- Oct-01 10- Oct-01 11- Oct-01 12- Oct-01 13- Oct-01 14- Oct-01 15- Oct-01 16- Oct-01 17- Oct-01 18- Oct-OI 24- Oci-01 25- Oct-01 26- Oct-01 27- Oci-01 28- Oct-01 29- Oct-01 30- Oct-01 31- Oct-01 18 23 24 28 30 32 3.9 3.9 3.8 3.6 3.6 3.5 83.4 41.2 7.4 0.2 26.9 17.8 0.7 25.7 35.4 3.8 122.6 98.2 0.3 39.1 74.9 100.4 0.4 43.6 68.7 82.7 129.1 182.5 151.5 214.7 195.3 0.2 49.8 81.8 102.7 234.6 117 A P P E N D I X C Date Harvested Product Data Mass P Theoretical % > 2 m m % 1-2 mm % 0.5-1 mm %< 0.5mm Mean Crystal Removed Mass M A P Size (mm) (g) Grown (g) 2-Sep-01 0.7 5.5 4-Sep-01 -5.4 -43.1 5-Sep-01 -0.6 -4.5 13-Sep-01 3.4 26.7 14-Sep-01 3.5 27.4 15-Sep-01 4.5 35.7 16-Sep-01 4.9 38.9 17-Sep-01 -2.2 -17.4 18-Sep-01 1.0 7.6 19-Sep-01 4.4 34.7 20-Sep-01 3.9 30.8 21-Sep-01 4.2 32.9 22-Sep-01 6.8 54.2 23-Sep-01 5.5 43.2 24-Sep-01 -10.8 -85.8 2-Oct-01 9.4 74.6 3-Oct-01 10.3 81.2 4-Oct-01 11.8 93.5 5-Oct-01 7.5 59.7 10-Oct-01 15.9 125.6 11-Oct-01 41.9 331.9 12-Oct-01 . 64.6 31.9 0.5 3.0 2.1 30.8 243.7 13-Oct-01 31.4 248.6 14-Oct-01 28.5 225.7 15-Oct-01 35.8 283.6 16-Oct-01 4.0 14.7 14.1 67.2 0.6 35.2 278.4 17-Oct-01 0.2 11.7 23.3 64.8 0.5 32.0 253.8 18-Oct-01 35.6 282.1 24-Oct-01 28.9 229.2 25-Oct-01 35.5 281.1 26-Oct-01 0.2 18.2 34.9 46.8 0.7 30.6 242.5 27-Oct-OI 32.6 258.5 28-Oct-01 0.2 22.3 35.2 42.3 0.7 28.3 224.0 29-Oct-01 32.7 258.9 30-Oct-01 0.1 21.2 34.9 43.8 0.7 31.6 250.2 31-Oct-01 32.0 253.4 118 A P P E N D I X C Date Notes 2-Sep-01 4- Sep-01 5- Sep-01 13- Sep-01 14- Sep-01 15- Sep-01 16- Sep-01 17- Sep-01 18- Sep-01 19- Sep-01 20- Sep-01 21- Sep-01 22- Sep-01 Mg Feed off 23- Sep-01 24- Sep-01 Power Failure 2- Oct-01 3- Oct-01 4- Oct-01 5- Oct-01 10- Oct-01 11- Oct-01 12- Oct-01 13- Oct-01 14- Oct-01 15- Oct-01 16- Oct-01 17- Oct-01 18- Oct-01 24- Oct-01 25- Oct-01 26- Oct-01 27- Oct-01 28- Oct-01 29- Oct-01 30- Oct-01 31- Oct-01 119 Date M g C l Feed Supernatant Lab results Effluent Lab results p H M g PO4-P N H 4 . N M g PO4-P N H 4 . N M g (mg/1) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) 1-NOV-01 733 46.7 284 25.8 9.0 272 32.3 8.3 2-NOV-01 733 46.4 283 25.5 7.8 262 31.5 8.4 7-NOV-01 733 46.4 324 30.1 12.3 262 29.8 8.1 8-NOV-01 733 45.6 298 28.8 6.0 230 25.5 8.6 9-NOV-01 733 45.9 302 29.1 6.2 245 24.9 8.6 10-NOV-01 733 46.3 274 28.8 6.6 244 22.8 8.6 11-NOV-01 733 54.8 298 29.7 5.7 220 33.9 8.6 12-NOV-01 733 53.7 267 30.7 6.4 230 27.7 8.6 13-Nov-OI 733 54.8 284 29.4 8.8 256 18.1 8.4 14-Nov-01 495 53.0 304 32.4 9.0 255 17.9 8.4 15-Nov-01 495 51.9 299 30.6 6.4 267 20.2 8.5 16-Nov-01 495 51.9 299 30.6 6.4 267 20.2 8.5 17-Nov-01 495 51.9 299 30.6 6.4 267 20.2 8.5 18-Nov-01 495 51.9 273 29.3 6.2 236 23.9 8.5 19-Nov-01 495 61.2 197 30.3 6.1 176 38.3 8.6 20-Nov-01 495 59.8 354 28.3 4.1 275 69.2 8.5 21-Nov-01 495 64.0 365 28.9 11.5 309 13.1 8.5 22-Nov-01 495 63.7 360 27.1 10.2 299 15.1 8.5 23-Nov-01 495 61.5 369 29.9 11.0 317 15.4 8.5 24-Nov-01 623 60.2 356 27.1 8.3 305 17.7 8.5 25-Nov-01 623 60.2 356 27.1 8.3 305 17.7 8.5 26-Nov-01 623 60.2 356 27.1 8.3 305 17.7 8.5 27-Nov-01 623 61.5 354 26.3 8.3 305 18.4 8.5 28-Nov-01 623 60.6 366 27.3 7.7 312 19.7 8.5 29-Nov-OI 623 61.7 346 28.2 8.6 285 17.1 8.5 30-Nov-01 623 58.5 359 25.7 7.4 296 17.5 8.5 1-Dec-01 623 65.2 380 26.3 12.4 305 17.8 8.4 2-Dec-01 623 68.1 406 26.0 17.0 345 22.3 8.1 3-Dec-01 623 67.2 391 26.1 13.7 338 17.9 8.5 4-Dec-01 623 69.2 436 24.9 12.0 351 19.5 8.3 5-Dec-01 616 69.1 400 29.5 12.1 336 18.7 8.4 6-Dec-01 616 68.2 398 25.4 7.8 354 15.1 8.7 7-Dec-01 616 71.1 399 25.4 11.8 330 18.3 8.4 8-Dec-01 616 71.1 399 25.4 11.8 330 18.3 8.4 9-Dec-01 616 71.1 399 25.4 11.8 330 18.3 8.4 10-Dec-01 616 71.1 399 25.4 11.8 330 18.3 8.4 11-Dec-01 616 71.2 409 23.7 11.5 332 17.7 8.4 12-Dec-01 616 65.7 426 29.4 10.5 320 18.2 8.4 13-Dec-01 616 64.6 399 30.6 12.4 346 16.1 8.4 ) c t12 -Dec13 Average 647 55.1 330 26.8 9.3 281 25.9 8.5 Minimum 495 37.2 197 11.1 4.1 176 13.1 8.1 Maximum 792 71.2 436 35.1 17.7 354 69.5 8.7 St.Dev. 96 10.3 53 4.5 2.9 41 11.9 0.1 Count 55 55 55 55 55 55 55 55 A P P E N D I X C Date M g C l Caustic Total Supernatant Recycle Total flow Flow Flow Influent Flow Flow Flow (influent+recycle) (mL/min) (1/day) (mL/min) (mL/min) (mL/min) (mL/min) 1-NOV-01 41 65 720 634 2880 3600 2-NOV-01 42 70 710 619 2890 3600 7-NOV-01 40 30 690 629 2810 3500 8-NOV-01 28 40 460 404 2990 3450 9-NOV-01 28 47.5 500 439 3000 3500 10-NOV-01 28 25 510 465 3040 3550 11-NOV-01 29 25 280 234 3320 3600 12-NOV-01 27 30 380 332 2870 3250 13-NOV-01 28 30 560 511 2990 3550 14-NOV-01 26 37.5 590 538 3010 3600 15-NOV-01 27 30 530 482 3000 3530 16-NOV-01 27 30 470 422 2995 3465 17-NOV-01 27 30 415 367 2985 3400 18-NOV-01 27 15 390 353 3010 3400 19-NOV-01 28 30 250 201 3500 3750 20-NOV-01 26 17.5 160 122 3540 3700 21-NOV-01 27 42.5 590 533 2860 3450 22-NOV-01 28 45 540 481 3010 3550 23-NOV-01 27 25 520 476 3080 3600 24-NOV-01 26 40 540 486 2910 3450 25-NOV-01 26 40 540 486 2910 3450 26-Nov-01 26 40 540 486 2910 3450 27-Nov-OI 27 30 520 472 2930 3450 28-Nov-OI 31 25 550 502 2800 3350 29-Nov-01 21 30 400 358 3200 3600 30-Nov-OI 21 27.5 380 340 3220 3600 1-Dec-01 22 30 390 347 3235 3625 2-Dec-01 21 32.5 360 316 3280 3640 3-Dec-01 22 40 450 400 3200 3650 4-Dec-01 22 70 390 319 3160 3550 5-Dec-01 22 20 400 364 3175 3575 6-Dec-01 23 20 360 323 3190 3550 7-Dec-01 21 1.25 390 368 3140 3530 8-Dec-01 21 1.25 390 368 3140 3530 9-Dec-01 21 1.25 390 368 3140 3530 10-Dec-01 21 1.25 390 368 3140 3530 11-Dec-01 21 30 360 318 3200 3560 12-Dec-01 21 15 360 329 3190 3550 13-Dec-01 22 30 410 367 3190 3600 )ct 12-Dec 13 Average 29 30 533 483 3021 3554 Minimum 0 1.25 160 122 2800 3250 Maximum 54 95 810 766 3540 3750 St.Dev. 11 18 163 155 174 91 Count 55 55 55 55 55 55 121 A P P E N D I X C Date Conditions at the inlet Removal efficiency (%) P 0 4 _ P N H 4 - N M g P 0 4 - P N H 4 . N M g (mg/L) (mg/L) (mg/L) 1-NOV-01 41.1 250 64.4 78 -9 50 2-NOV-01 40.5 247 65.6 81 -6 52 7-NOV-01 42.3 295 69.9 71 11 57 8-NOV-01 40.1 262 69.9 85 12 64 9-NOV-01 40.3 265 66.6 85 8 63 10-NOV-01 42.2 250 66.5 84 2 66 11-NOV-01 45.7 249 100.7 88 12 66 12-NOV-01 46.9 233 78.9 86 1 65 13-NOV-01 50.0 259 63.5 82 1 71 14-NOV-01 48.3 277 51.3 81 8 65 15-NOV-01 47.2 272 53.0 86 2 62 16-NOV-01 46.6 269 55.9 86 1 64 17-NOV-01 45.9 265 59.3 86 -1 66 18-NOV-01 46.9 247 60.7 87 4 61 19-NOV-01 49.2 159 79.8 88 -11 52 20-NOV-01 45.5 270 101.9 91 -2 32 21-NOV-01 57.9 330 48.8 80 6 73 22-NOV-01 56.7 321 49.8 82 7 70 23-NOV-01 56.2 338 53.0 80 6 71 24-NOV-01 54.2 321 54.4 85 5 67 25-NOV-01 54.2 321 54.4 85 5 67 26-Nov-01 54.2 321 54.4 85 5 67 27-Nov-01 55.8 321 56.2 85 5 67 28-Nov-01 55.2 334 60.0 86 7 67 29-Nov-01 55.2 310 58.0 84 8 70 30-Nov-01 52.3 321 57.4 86 8 70 1-Dec-01 58.0 338 58.6 79 10 70 2-Dec-01 59.8 357 59.2 72 3 62 3-Dec-01 59.8 348 53.7 77 3 67 4-Dec-01 56.6 357 55.5 79 2 65 5-Dec-01 62.9 364 60.7 81 8 69 6-Dec-01 61.2 357 62.1 87 1 76 7-Dec-01 67.1 377 57.1 82 12 68 8-Dec-01 67.1 377 57.1 82 12 68 9-Dec-01 67.1 377 57.1 82 12 68 10-Dec-01 67.1 377 57.1 82 12 68 11-Dec-01 62.9 361 56.9 82 8 69 12-Dec-01 59.9 389 62.7 83 18 71 13-Dec-01 57.8 357 60.4 79 3 73 )ct 12-Dec 13 Average 49.6 297 61.0 81 5 57 Minimum 33.5 159 18.6 60 -13 -2 Maximum 67.1 389 101.9 91 18 76 St.Dev. 9.3 49 12.3 6 6 17 Count 55 55 55 55 55 55 122 Date Molar removal Inlet to outlet P 0 4 _ P N H 4 - N M g M g : P N:P Removal Removal Ratio Ratio 1-NOV-01 1.OE-03 -1.6E-03 1.3E-03 1.3 -1.5 2-NOV-01 1.1 E-03 -1.1 E-03 1.4E-03 1.3 -1.0 7-NOV-01 9.7E-04 2.4E-03 1.7E-03 1.7 2.5 8-NOV-01 1.1 E-03 2.3E-03 1.8E-03 1.7 2.1 9-NOV-01 1.1 E-03 1.4E-03 1.7E-03 1.6 1.3 10-NOV-01 1.1 E-03 4.0E-04 1.8E-03 1.6 0.3 11-NOV-01 1.3E-03 2.0E-03 2.7E-03 2.1 1.6 12-NOV-01 1.3E-03 2.4E-04 2.1 E-03 1.6 0.2 13-NOV-01 1.3E-03 2.3E-04 1.9E-03 1.4 0.2 14-NOV-01 1.3E-03 1.6E-03 1.4E-03 1.1 1.2 15-NOV-01 1.3E-03 3.6E-04 1.4E-03 1.0 0.3 16-NOV-01 1.3E-03 1.1E-04 1.5E-03 1.1 0.1 17-NOV-01 1.3E-03 -1.8E-04 1.6E-03 1.3 -0.1 18-NOV-01 1.3E-03 7.7E-04 1.5E-03 1.2 0.6 19-NOV-01 1.4E-03 -1.2E-03 1.7E-03 1.2 -0.9 20-NOV-01 1.3E-03 -3.9E-04 1.3E-03 1.0 -0.3 21-NOV-01 1.5E-03 1.5E-03 1.5E-03 1.0 1.0 22-NOV-01 1.5E-03 1.5E-03 1.4E-03 1.0 1.0 23-NOV-01 1.5E-03 1.5E-03 1.5E-03 1.1 1.0 24-NOV-01 1.5E-03 1.1 E-03 1.5E-03 1.0 0.7 25-NOV-01 1.5E-03 1.1 E-03 1.5E-03 1.0 0.7 26-Nov-OI 1.5E-03 1.1 E-03 1.5E-03 1.0 0.7 27-Nov-01 1.5E-03 1.2E-03 1.6E-03 1.0 0.8 28-Nov-01 1.5E-03 1.6E-03 1.7E-03 1.1 1.0 29-Nov-01 1.5E-03 1.8E-03 1.7E-03 1.1 1.2 30-Nov-01 1.5E-03 1.8E-03 1.6E-03 1.1 1.2 1-Dec-01 1.5E-03 2.4E-03 1.7E-03 1.1 1.6 2-Dec-01 1.4E-03 8.5E-04 1.5E-03 1.1 0.6 3-Dec-01 1.5E-03 7.0E-04 1.5E-03 1.0 0.5 4-Dec-01 1.4E-03 4.3E-04 1.5E-03 1.0 0.3 5-Dec-01 1.6E-03 2.0E-03 1.7E-03 1.1 1.2 6-Dec-01 1.7E-03 2.3E-04 1.9E-03 1.1 0.1 7-Dec-01 1.8E-03 3.3E-03 1.6E-03 0.9 1.9 8-Dec-01 1.8E-03 3.3E-03 1.6E-03 0.9 1.9 9-Dec-01 1.8E-03 3.3E-03 1.6E-03 0.9 1.9 10-Dec-01 1.8E-03 3.3E-03 1.6E-03 0.9 1.9 11-Dec-01 1.7E-03 2.1 E-03 1.6E-03 1.0 1.3 12-Dec-01 1.6E-03 4.9E-03 1.8E-03 1.1 3.1 13-Dec-01 1.5E-03 8.1E-04 1.8E-03 1.2 0.6 ) c t12 -Dec13 Average 1.3E-03 1.2E-03 1.4E-03 1.1 0.9 Minimum 8.4E-04 -2.5E-03 -6.3E-05 -0.1 -2.2 Maximum 1.8E-03 4.9E-03 2.7E-03 2.1 3.5 St.Dev. 2.7E-04 1.3E-03 4.7E-04 0.4 1.0 Count 55 55 55 55 55 A P P E N D I X C Date PO 4 -P In-Reactor N H , -N In-Reactor Feed gives Recycle gives Total Feed gives Recycle gives Total (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L] 1-Nov-01 8.2 7.2 15.4 50 218 268 2-Nov-01 8.0 6.3 14.2 49 210 259 7-Nov-01 8.3 9.9 18.2 58 210 269 8-Nov-01 5.3 5.2 10.5 35 199 234 9-Nov-OI 5.8 5.3 11.1 38 210 248 10-Nov-01 6.1 5.7 11.7 36 209 245 11-Nov-01 3.6 5.3 8.8 19 203 222 12-Nov-01 5.5 5.7 11.1 27 203 230 13-Nov-OI 7.9 7.4 15.3 41 216 257 14-Nov-01 7.9 7.5 15.4 45 213 259 15-Nov-01 7.1 5.4 12.5 41 227 268 16-Nov-01 6.3 5.5 11.9 36 231 267 17-Nov-01 5.6 5.6 11.2 32 234 267 18-Nov-OI 5.4 5.5 10.9 28 209 237 19-Nov-01 3.3 5.7 9.0 11 164 175 20-Nov-OI 2.0 3.9 5.9 12 263 275 21-Nov-OI 9.9 9.5 19.4 56 256 313 22-Nov-01 8.6 8.6 17.3 49 254 302 23-Nov-01 8.1 9.4 17.5 49 271 320 24-Nov-01 8.5 7.0 15.4 50 257 307 25-Nov-OI 8.5 7.0 15.4 50 257 307 26-Nov-01 8.5 7.0 15.4 50 257 307 27-Nov-01 8.4 7.0 15.5 48 259 307 28-Nov-01 9.1 6.4 15.5 55 261 316 29-Nov-01 6.1 7.6 13.8 34 253 288 30-Nov-01 5.5 6.6 12.1 34 265 299 1-Dec-01 6.2 11.0 17.3 36 272 309 2-Dec-01 5.9 15.3 21.2 35 311 346 3-Dec-01 7.4 12.0 19.4 43 296 339 4-Dec-01 6.2 10.7 16.9 39 312 352 5-Dec-01 7.0 10.7 17.8 41 298 339 6-Dec-01 6.2 7.0 13.2 36 318 354 7-Dec-01 7.4 10.5 17.9 42 294 335 8-Dec-01 7.4 10.5 17.9 42 294 335 9-Dec-01 7.4 10.5 17.9 42 294 335 10-Dec-01 7.4 10.5 17.9 42 294 335 11-Dec-01 6.4 10.3 16.7 37 298 335 12-Dec-01 6.1 9.4 15.5 39 288 327 13-Dec-01 6.6 11.0 17.6 41 307 347 )ct 12-Dec 13 Average 7.2 7.9 15.1 44 239 283 Minimum 2.0 3.8 5.9 11 164 175 Maximum 9.9 15.3 23.2 60 318 354 St.Dev. 1.6 2.5 3.4 11 42 41 Count 55 55 55 55 55 55 124 Date Mg In-Reactor In-Reactor Concentrations In-Reacor Mg:P In-Reactor N:P Feed gives Recycle gives Total P0 4_P NH 4 -N Mg (molar ratio) (molar ratio) (mg/L) (mg/L) (mg/L) (mol/L) (mol/L) (mol/L) 1-NOV-01 12.9 25.8 38.7 5.0E-04 1.9E-02 1.6E-03 3.2 38.4 2 -NOV -01 12.9 25.3 38.2 4.6E-04 1.9E-02 1.6E-03 3.4 40.2 7-NOV-01 13.8 23.9 37.7 5.9E-04 1.9E-02 1.6E-03 2.6 32.6 8-NOV-01 9.3 22.1 31.4 3.4E-04 1.7E-02 1.3E-03 3.8 49.2 9 -NOV -01 9.5 21.3 30.9 3.6E-04 1.8E-02 1.3E-03 3.6 49.5 10-NOV-01 9.6 19.5 29.1 3.8E-04 1.7E-02 1.2E-03 3.2 46.2 11-NOV-01 7.8 31.3 39.1 2.8E-04 1.6E-02 1.6E-03 5.7 55.8 12-NOV-01 9.2 24.5 33.7 3.6E-04 1.6E-02 1.4E-03 3.9 45.8 13-NOV-01 10.0 15.2 25.3 4.9E-04 1.8E-02 1.OE-03 2.1 37.1 14-NOV-01 8.4 15.0 23.4 5.0E-04 1.8E-02 9.6E-04 1.9 37.0 15-NOV-01 8.0 17.2 25.1 4.0E-04 1.9E-02 1.OE-03 2.6 47.3 16-NOV-01 7.6 17.5 25.0 3.8E-04 1.9E-02 1.OE-03 2.7 49.9 17 -NOV -01 7.2 17.7 25.0 3.6E-04 1.9E-02 1.OE-03 2.8 52.6 18 -NOV -01 7.0 21.2 28.1 3.5E-04 1.7E-02 1.2E-03 3.3 48.3 19-NOV-01 5.3 35.7 41.1 2.9E-04 1.2E-02 1.7E-03 5.8 43.1 20 -NOV -01 4.4 66.2 70.6 1.9E-04 2.0E-02 2.9E-03 15.3 103.2 21 -NOV -01 8.3 10.9 19.2 6.3E-04 2.2E-02 7.9E-04 1.3 35.7 22 -NOV -01 7.6 12.8 20.4 5.6E-04 2.2E-02 8.4E-04 1.5 38.7 23 -NOV -01 7.7 13.2 20.8 5.7E-04 2.3E-02 8.6E-04 1.5 40.4 24 -NOV -01 8.5 14.9 23.4 5.0E-04 2.2E-02 9.6E-04 1.9 44.1 25 -NOV -01 8.5 14.9 23.4 5.0E-04 2.2E-02 9.6E-04 1.9 44.1 26-Nov-OI 8.5 14.9 23.4 5.0E-04 2.2E-02 9.6E-04 1.9 44.1 27-Nov-01 8.5 15.6 24.1 5.0E-04 2.2E-02 9.9E-04 2.0 44.0 28-Nov-01 9.9 16.5 26.3 5.0E-04 2.3E-02 1.1 E-03 2.2 45.2 29-Nov-01 6.4 15.2 21.6 4.5E-04 2.1 E-02 8.9E-04 2.0 46.2 30-Nov-01 6.1 15.7 21.7 3.9E-04 2.1 E-02 8.9E-04 2.3 54.4 1-Dec-01 6.3 15.9 22.2 5.6E-04 2.2E-02 9.1E-04 1.6 39.5 2-Dec-01 5.9 20.1 25.9 6.8E-04 2.5E-02 1.1 E-03 1.6 36.1 3-Dec-01 6.6 15.7 22.3 6.3E-04 2.4E-02 9.2E-04 1.5 38.7 4-Dec-01 6.1 17.4 23.5 5.5E-04 2.5E-02 9.7E-04 1.8 46.0 5-Dec-01 6.8 16.6 23.4 5.7E-04 2.4E-02 9.6E-04 1.7 42.2 6-Dec-01 6.3 13.6 19.9 4.3E-04 2.5E-02 8.2E-04 1.9 59.5 7-Dec-01 6.3 16.3 22.6 5.8E-04 2.4E-02 9.3E-04 1.6 41.4 8-Dec-01 6.3 16.3 22.6 5.8E-04 2.4E-02 9.3E-04 1.6 41.4 9-Dec-01 6.3 16.3 22.6 5.8E-04 2.4E-02 9.3E-04 1.6 41.4 10-Dec-01 6.3 16.3 22.6 5.8E-04 2.4E-02 9.3E-04 1.6 41.4 11-Dec-01 5.7 15.9 21.7 5.4E-04 2.4E-02 8.9E-04 1.7 44.5 12-Dec-01 6.4 16.4 22.7 5.0E-04 2.3E-02 9.3E-04 1.9 46.8 13-Dec-01 6.9 14.3 21.1 5.7E-04 2.5E-02 8.7E-04 1.5 43.7 )ct 12-Dec 13 Average 9.0 21.9 30.9 4.9E-04 2.0E-02 1.3E-03 2.9 43.2 Minimum 3.9 10.9 15.5 1.9E-04 1.2E-02 6.4E-04 0.9 27.0 Maximum 14.4 66.2 70.6 7.5E-04 2.5E-02 2.9E-03 15.3 103.2 St.Dev. 3.0 10.1 11.4 1.1E-04 3.0E-03 4.7E-04 2.1 10.6 Count 55 55 55 55 55 55 55 55 A P P E N D I X C Date Feed P s In-Reactor P s Equil ibrium P s Feed In-Reactor Effluent Crystal Harvest S.S. ratio S.S. Ratio S.S. Ratio Volume Volume (I) (1) 1-NOV-01 6.3E-08 1.5E-08 6.7E-09 9.4 2.3 1.1 6.70 1.1 2-NOV-01 6.2E-08 1.3E-08 5.7E-09 10.9 2.3 1.1 6.35 7-NOV-01 8.3E-08 1.8E-08 9.5E-09 8.7 1.8 1.0 6.80 1.1 8-NOV-01 7.0E-08 7.4E-09 4.3E-09 16.3 1.7 0.8 6.25 9-NOV-01 6.8E-08 8.0E-09 4.3E-09 15.8 1.9 0.8 6.65 10-NOV-01 6.6E-08 7.9E-09 4.3E-09 15.5 1.8 0.8 7.10 1.1 11-NOV-01 1.1E-07 7.3E-09 4.3E-09 25.4 1.7 0.9 6.00 12-NOV-01 8.2E-08 8.2E-09 4.3E-09 19.2 1.9 0.9 6.50 13-NOV-01 7.8E-08 9.4E-09 5.7E-09 13.6 1.6 0.7 6.90 1.1 14-NOV-01 6.5E-08 8.9E-09 5.7E-09 11.4 1.5 0.7 6.30 15-NOV-01 6.5E-08 8.0E-09 4.9E-09 13.1 1.6 0.7 6.80 16-NOV-01 6.6E-08 7.5E-09 4.9E-09 13.5 1.5 0.7 7.30 17-NOV-01 6.8E-08 7.1E-09 4.9E-09 13.9 1.4 0.7 7.75 18-NOV-01 6.7E-08 6.9E-09 4.9E-09 13.5 1.4 0.7 8.10 1.1 19-NOV-01 5.9E-08 6.1E-09 4.3E-09 13.8 1.4 0.9 7.40 20-NOV-01 1.2E-07 1.1E-08 4.9E-09 24.1 2.2 1.5 7.30 1.1 21-NOV-01 8.8E-08 1.1E-08 4.9E-09 17.9 2.2 0.9 7.10 22-NOV-01 8.6E-08 1.0E-08 4.9E-09 17.4 2.0 0.9 7.65 1.1 23-NOV-01 9.5E-08 1.1E-08 4.9E-09 19.4 2.3 1.0 7.05 24-NOV-01 9.0E-08 1.1E-08 4.9E-09 18.2 2.1 0.9 7.65 25-NOV-01 9.0E-08 1.1E-08 4.9E-09 18.2 2.1 0.9 8.25 26-Nov-01 9.0E-08 1.1E-08 4.9E-09 18.2 2.1 0.9 8.55 1.1 27-Nov-01 9.6E-08 1.1E-08 4.9E-09 19.4 2.2 0.9 8.25 1.1 28-Nov-01 1.1E-07 1.2E-08 4.9E-09 21.3 2.5 0.9 7.95 1.1 29-Nov-OI 9.4E-08 8.1E-09 4.9E-09 19.1 1.7 0.8 7.25 30-Nov-01 9.2E-08 7.5E-09 4.9E-09 18.6 1.5 0.7 7.65 1.1 1-Dec-01 1.1E-07 1.1E-08 5.7E-09 19.1 2.0 1.1 7.00 2-Dec-01 1.2E-07 1.8E-08 9.5E-09 12.6 1.9 1.3 7.30 3-Dec-01 1.1E-07 1.4E-08 4.9E-09 21.5 2.8 1.6 7.85 1.1 4-Dec-01 1.1E-07 1.3E-08 6.7E-09 15.9 2.0 1.2 7.10 5-Dec-01 1.3E-07 1.3E-08 5.7E-09 23.0 2.3 1.3 7.30 6-Dec-01 1.3E-07 8.8E-09 3.8E-09 34.4 2.3 1.0 7.65 1.1 7-Dec-01 1.4E-07 1.3E-08 5.7E-09 23.9 2.2 1.2 8-Dec-01 1.4E-07 1.3E-08 5.7E-09 23.9 2.2 1.2 9-Dec-01 1.4E-07 1.3E-08 5.7E-09 23.9 2.2 1.2 10-Dec-01 1.4E-07 1.3E-08 5.7E-09 23.9 2.2 1.2 8.10 1.1 11-Dec-01 1.2E-07 1.1E-08 5.7E-09 21.4 2.0 1.1 7.25 12-Dec-01 1.4E-07 1.1E-08 5.7E-09 24.2 1.9 1.0 7.60 1.1 13-Dec-01 1.2E-07 1.2E-08 5.7E-09 20.7 2.1 1.1 6.90 1.1 )ct 12-Dec 13 Average 8.6E-08 1.2E-08 5.4E-09 16.2 2.2 1.1 6.74 1.1 Minimum 2.2E-08 6.1E-09 3.8E-09 4.5 1.4 0.7 3.84 0.7 Maximum 1.4E-07 2.6E-08 9.5E-09 34.4 3.8 2.3 8.55 1.1 St.Dev. 2.8E-08 3.9E-09 1.2E-09 5.8 0.6 0.4 1.10 0.1 Count 55 55 55 55 55 55 52 22 126 A P P E N D I X C Date C R T C R T Averaged Harvested Product Data Actual In reactor > 2 mm > 1 mm > 0.5 mm < 0.5 mm Total Mass (days) SS Ratio (g) (g) (g) (g) (g) 1-Nov-01 12 2.4 0.3 85.9 86.9 83.0 256.1 2-Nov-01 7-Nov-01 14 2.4 0.2 103.8 82.4 92.7 279.1 8-NOV-01 9-Nov-01 10-Nov-01 14 2.2 0.1 85.6 140.4 156.8 382.8 11-Nov-OI 12-Nov-OI 13-Nov-01 13 2.0 5.9 216.1 66.9 59.1 348.0 14-Nov-01 15-Nov-01 16-Nov-01 17-Nov-OI 18-Nov-01 19 1.9 0.6 153.5 108.1 105.3 367.5 19-Nov-01 20-Nov-01 17 1.8 11.7 216.9 89.8 47.0 365.4 21-Nov-01 22-Nov-01 18 1.8 24.5 228.3 74.1 52.3 379.2 23-Nov-01 24-Nov-01 25-Nov-01 26-Nov-01 21 1.9 24.6 253.2 55.6 36.3 369.7 27-Nov-01 19 1.9 6.6 246.8 71.9 59.0 384.3 28-Nov-01 17 1.9 13.1 282.7 73.1 34.3 403.2 29-Nov-01 30-Nov-OI 13 2.0 25.7 295.0 79.3 26.6 426.6 1-Dec-01 2-Dec-01 3-Dec-01 14 2.1 7.4 304.8 165.2 22.4 499.8 4-Dec-01 5-Dec-01 6-Dec-01 15 2.1 11.4 368.3 139.7 11.3 530.6 7-Dec-01 8-Dec-01 9-Dec-01 10-Dec-01 16 2.2 6.1 368.9 154.7 14.4 544.0 11-Dec-01 12-Dec-01 16 2.1 7.4 457.4 94.8 5.6 565.1 13-Dec-01 15 2.1 9.9 475.5 126.1 1.1 612.6 )ct 12-Dec 13 Average 19 2.5 11.2 198.2 86.2 59.9 355.5 Minimum 12 1.8 0.1 17.8 0.7 1.1 129.1 Maximum 32 3.9 83.4 475.5 165.2 156.8 612.6 St.Dev. 6 0.8 18.1 143.3 40.7 43.8 139.0 Count 22 22 22 22 22 22 22 127 A P P E N D I X C Date Harvested Product Data Mass P Theoretical % > 2 m m % 1-2 mm %0.5 - lmm %< 0.5mm Mean Crystal Removed Mass M A P Size (mm) (g) Grown 1-NOV-01 0.1 33.5 33.9 32.4 0.8 33.3 263.7 2-NOV-01 33.4 264.6 7-NOV-01 0.1 37.2 29.5 33.2 0.9 29.8 236.1 8-NOV-01 22.6 178.7 9-NOV-01 24.6 194.5 10-NOV-01 0.0 22.3 36.7 40.9 0.7 26.1 206.9 11-NOV-01 16.1 127.8 12-NOV-01 22.2 175.7 13-NOV-01 1.7 62.1 19.2 17.0 1.2 33.2 263.3 14-NOV-01 33.4 264.6 15-NOV-01 31.2 246.7 16-NOV-01 27.2 215.6 17-NOV-01 23.6 187.0 18-NOV-01 0.2 41.8 29.4 28.7 0.9 22.9 181.1 19-NOV-01 15.5 123.0 20-NOV-01 3.2 59.4 24.6 12.9 1.2 9.5 75.6 21-NOV-01 39.4 312.3 22-NOV-01 6.5 60.2 19.5 13.8 1.2 36.2 286.4 23-NOV-01 33.9 268.1 24-NOV-01 35.7 282.7 25-NOV-01 35.7 282.7 26-Nov-OI 6.7 68.5 15.0 9.8 1.3 35.7 282.7 27-Nov-01 1.7 64.2 18.7 15.3 1.2 35.6 281.9 28-Nov-01 3.3 70.1 18.1 8.5 1.3 37.7 298.4 29-Nov-01 26.9 212.8 30-Nov-01 6.0 69.1 18.6 6.2 1.3 24.6 194.7 1-Dec-01 25.7 203.2 2-Dec-01 22.2 176.0 3-Dec-01 1.5 61.0 33.0 4.5 1.2 29.9 236.4 4-Dec-01 25.1 198.5 5-Dec-01 29.2 231.5 6-Dec-01 2.1 69.4 26.3 2.1 1.3 27.7 219.3 7-Dec-01 31.0 245.8 8-Dec-01 31.0 245.8 9-Dec-01 31.0 245.8 10-Dec-01 1.1 67.8 28.4 2.6 1.3 31.0 245.8 11-Dec-01 26.7 211.2 12-Dec-01 1.3 80.9 16.8 1.0 1.4 25.6 203.1 13-Dec-01 1.6 77.6 20.6 0.2 1.4 26.8 212.3 )ct 12-Dec 13 Average 4.8 48.4 24.2 22.6 1.1 29.5 233.3 Minimum 0.0 11.7 0.5 0.2 0.5 9.5 75.6 Maximum 64.6 80.9 36.7 67.2 2.1 39.4 312.3 St.Dev. 13.5 22.9 9.0 20.9 0.4 5.8 46.0 Count 22 22 22 22 22 55 55 128 A P P E N D I X C Date Notes 1- Nov-01 2- Nov-01 7- Nov-01 8- Nov-01 9- Nov-01 10- Nov-01 11- Nov-01 12- Nov-01 13- NOV-01 14- Nov-OI 15- Nov-01 16- Nov-01 17- Nov-01 18- Nov-01 19- Nov-01 20- Nov-01 21- Nov-01 22- Nov-01 23- Nov-01 24- Nov-01 25- Nov-01 26- Nov-01 27- Nov-01 28- Nov-01 29- Nov-01 30- Nov-01 1- Dec-01 2- Dec-01 3- Dec-01 4- Dec-01 5- Dec-01 6- Dec-01 7- Dec-01 8- Dec-01 9- Dec-01 10- Dec-01 11- Dec-01 12- Dec-01 13- Dec-01 Oct 12-Dec 13 Average Minimum Maximum St.Dev. Count 129 A P P E N D I X D APPENDIX D: OPERATING DATA FOR REACTOR B 130 A P P E N D I X D Date M g C l Feed Supernatant L a b results Effluent L a b results P H M g P 0 4 - P N H 4 . N M g PO4-P N H 4 . N M g (mg/1) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) 2-Sep-01 1092 9.4 263 28.0 6.7 234 94.0 8.4 4-Sep-01 1092 8.3 284 27.3 8.1 263 91.0 8.5 5-Sep-01 1092 8.0 270 41.9 6.3 248 86.0 8.4 6-Sep-01 1092 7.8 263 27.8 6.0 220 8.4 7-Sep-01 1092 10.9 270 29.3 9.0 262 65.3 8.4 13-Sep-01 714 10.2 273 16.7 7.8 256 59.8 8.9 14-Sep-01 714 10.5 283 16.2 7.6 268 55.6 8.8 15-Sep-01 986 10.8 271 14.9 7.5 249 69.4 8.8 16-Sep-01 986 12.1 314 16.9 17.7 276 65.0 6.8 17-Sep-01 986 12.1 282 15.7 10.8 235 78.1 8.3 18-Sep-01 986 11.9 298 16.0 9.3 252 65.0 8.3 19-Sep-01 986 13.7 272 16.1 9.0 235 69.1 8.6 20-Sep-01 986 11.7 277 14.4 8.6 270 70.9 8.7 21-Sep-01 977 11.5 277 13.5 8.0 267 75.9 8.7 22-Sep-01 977 12.8 279 11.7 13.9 263 25.8 8.7 23-Sep-01 977 12.6 281 16.4 10.4 267 77.1 8.7 24-Sep-01 977 12.3 276 13.4 16.4 194 115.0 8.8 2-Oct-01 977 12.3 290 21.1 8.5 259 78.0 8.8 3-Oct-01 977 11.8 262 21.4 7.4 240 87.0 8.8 5-Oct-01 792 18.0 260 29.7 18.9 248 61.1 8.6 10-Oct-01 792 17.8 265 28.8 7.1 235 53.8 8.8 11-Oct-01 792 43.4 252 30.3 26.4 249 38.2 8.8 12-Oct-01 792 44.3 314 11.1 12.6 240 63.8 8.4 13-Oct-01 792 42.3 279 14.8 10.7 242 49.4 8.4 14-Oct-01 792 43.5 282 14.1 9.4 246 45.0 8.4 15-Oct-01 792 46.2 285 35.1 13.0 274 34.3 8.4 16-Oct-01 792 44.9 295 34.3 11.0 261 37.4 8.4 17-Oct-01 792 45.8 299 28.3 8.8 270 42.1 8.5 18-Oct-01 792 48.7 284 29.3 12.1 258 30.9 8.5 24-Oct-01 792 44.5 290 18.9 18.2 280 17.3 8.4 25-Oct-01 657 43.9 302 21.1 7.8 241 38.6 8.4 26-Oct-01 657 37.2 289 24.3 5.8 250 43.4 8.4 27-Oct-01 657 42.9 293 26.3 6.4 265 44.2 8.4 28-Oct-01 657 40.4 245 29.1 8.4 237 35.1 8.4 29-Oct-01 657 40.1 293 24.7 6.5 233 47.9 8.4 30-Oct-01 657 39.9 293 21.7 6.3 227 48.0 8.4 31-Oct-01 733 45.6 295 23.4 11.4 251 43.0 8.3 131 A P P E N D I X D Date M g C l Caustic Total Supernatant Recycle Total flow Flow Flow Influent Flow Flow Flow (influent+recycle) (mL/min) (1/day) (mL/min) (mL/min) (mL/min) (mL/min) 2-Sep-01 48 103.5 833 713 2917 3750 4-Sep-01 50 100 850 731 2700 3550 5-Sep-01 48 75 950 850 2750 3700 6-Sep-01 49 0 925 876 2700 3625 7-Sep-01 49 0 1200 1151 2550 3750 13-Sep-01 50 10 925 868 2600 3525 14-Sep-01 50 7.5 850 795 2600 3450 15-Sep-01 50 5 950 897 2550 3500 16-Sep-01 58 7.5 1250 1187 2900 4150 17-Sep-01 65 80 1075 954 2775 3850 18-Sep-01 50 115 1000 870 2600 3600 19-Sep-01 52 150 925 769 2625 3550 20-Sep-01 54 5 900 843 2750 3650 21-Sep-01 53 7.5 1150 1092 2500 3650 22-Sep-01 0 2.5 1300 1298 2400 3700 23-Sep-01 53 15 1250 1187 2550 3800 24-Sep-01 54 5 1233 1176 2600 3833 2-Oct-01 54 15 1100 1036 2500 3600 3-Oct-01 53 20 1000 933 2500 3500 5-Oct-01 56 57.5 1300 1204 2550 3850 10-Oct-01 56 5 1200 1141 2450 3650 11-Oct-01 56 50 1225 1134 2475 3700 12-Oct-01 58 15 620 552 2880 3500 13-Oct-01 31 15 620 579 2880 3500 14-Oct-01 31 12.5 660 620 2865 3525 15-Oct-01 32 20 930 884 2870 3800 16-Oct-01 32 17.5 820 776 2855 3675 17-Oct-01 20 20 430 396 1970 2400 18-Oct-01 21 17.5 720 687 2930 3650 24-Oct-01 0 17.5 780 768 2890 3670 25-Oct-01 52 15 780 718 2770 3550 26-Oct-01 54 30 740 665 2860 3600 27-Oct-01 54 17.5 700 634 2850 3550 28-Oct-01 53 22.5 690 621 2885 3575 29-Oct-01 54 50 740 651 2860 3600 30-Oct-01 58 42.5 750 662 2825 3575 31-Oct-01 46 95 830 718 2820 3650 132 A P P E N D I X D Date Conditions at the inlet Removal efficiency (%) PO 4_P (mg/L) N H 4 - N (mg/L) M g (mg/L) PO 4 -P N H 4 . N M g 2-Sep-01 8.0 225 86.9 16 -4 -8 4-Sep-01 7.1 244 87.7 -14 -8 -4 5-Sep-01 7.1 242 92.7 12 -3 7 6-Sep-01 7.4 249 84.2 19 12 100 7-Sep-01 10.5 259 72.7 14 -1 10 13-Sep-01 9.6 256 54.3 19 0 -10 14-Sep-01 9.8 265 57.1 23 -1 3 15-Sep-01 10.2 256 65.9 26 3 -5 16-Sep-01 11.5 298 61.8 -54 7 -5 17-Sep-01 10.7 250 73.5 -1 6 -6 18-Sep-01 10.4 259 63.2 10 3 -3 19-Sep-01 11.4 226 68.8 21 -4 -1 20-Sep-01 11.0 259 72.6 21 -4 2 21-Sep-01 10.9 263 57.8 27 -2 -31 22-Sep-01 12.8 279 11.7 -9 6 -121 23-Sep-01 12.0 267 56.9 13 0 -35 24-Sep-01 11.7 263 55.5 -40 26 -107 2-Oct-01 11.6 273 67.8 27 5 -15 3-Oct-01 11.0 244 71.8 33 2 -21 5-Oct-01 16.7 241 61.6 -13 -3 1 10-Oct-01 16.9 252 64.3 58 7 16 11-Oct-01 40.2 233 64.3 34 -7 41 12-Oct-01 39.4 279 83.9 68 14 24 13-Oct-01 39.5 260 53.4 73 7 8 14-Oct-01 40.9 265 50.4 77 7 11 15-Oct-01 43.9 271 60.6 70 -1 43 16-Oct-01 42.5 279 63.3 74 6 41 17-Oct-01 42.2 275 62.9 79 2 33 18-Oct-01 46.5 271 51.0 74 5 40 24-Oct-01 43.8 285 18.6 58 2 7 25-Oct-01 40.4 278 63.2 81 13 39 26-Oct-01 33.4 260 69.8 83 4 38 27-Oct-01 38.8 265 74.5 84 0 41 28-Oct-01 36.4 221 76.7 77 -7 54 29-Oct-01 35.3 258 69.7 82 10 31 30-Oct-01 35.2 259 70.0 82 12 31 31-Oct-01 39.4 255 60.9 71 2 29 133 A P P E N D I X D Date M o l a r removal M g : P N :P Inlet to outlet Removal Removal P 0 4 _ P N H 4 - N M g Ratio Ratio 2-Sep-01 4.2E-05 -6.3E-04 -2.9E-04 -6.9 -14.9 4-Sep-01 -3.3E-05 -1.4E-03 -1.4E-04 4.1 41.0 5-Sep-01 2.7E-05 -4.6E-04 2.8E-04 10.2 -17.0 6-Sep-01 4.5E-05 2.1 E-03 3.5E-03 76.4 45.8 7-Sep-01 4.9E-05 -2.2E-04 3.1E-04 6.2 -4.4 13-Sep-01 5.7E-05 1.4E-05 -2.3E-04 -4.0 0.2 14-Sep-01 7.2E-05 -2.4E-04 6.4E-05 0.9 -3.4 15-Sep-01 8.7E-05 4.8E-04 -1.4E-04 -1.7 5.5 16-Sep-01 -2.0E-04 1.6E-03 -1.3E-04 0.7 -7.9 17-Sep-01 -1.8E-06 1.1 E-03 -1.9E-04 102.2 -597.2 18-Sep-01 3.4E-05 5.2E-04 -7.4E-05 -2.2 15.3 19-Sep-01 7.7E-05 -6.4E-04 -1.5E-05 -0.2 -8.3 20-Sep-01 7.6E-05 -7.6E-04 7.1E-05 0.9 -10.0 21-Sep-01 9.4E-05 -2.9E-04 -7.4E-04 -7.9 -3.0 22-Sep-01 -3.6E-05 1.1 E-03 -5.8E-04 16.2 -30.9 23-Sep-01 5.0E-05 -1.8E-05 -8.3E-04 -16.5 -0.4 24-Sep-01 -1.5E-04 4.9E-03 -2.4E-03 16.2 -32.7 2-Oct-01 9.9E-05 1.OE-03 -4.2E-04 -4.2 10.1 3-Oct-01 1.2E-04 3.2E-04 -6.3E-04 -5.4 2.7 5-Oct-01 -7.2E-05 -5.1E-04 1.8E-05 -0.3 7.1 10-Oct-01 3.2E-04 1.2E-03 4.3E-04 1.4 3.8 11-Oct-01 4.5E-04 -1.1 E-03 1.1 E-03 2.4 -2.5 12-Oct-01 8.7E-04 2 .8E-03 8.3E-04 1.0 3.2 13-Oct-01 9.3E-04 1.3E-03 1.6E-04 0.2 1.4 14-Oct-01 1.OE-03 1.4E-03 2.2E-04 0.2 1.3 15-Oct-01 1.OE-03 -2.2E-04 1.1 E-03 1.1 -0.2 16-Oct-01 1.OE-03 1.3E-03 1.1 E-03 1.0 1.3 17-Oct-01 1.1 E-03 3.9E-04 8.5E-04 0.8 0.4 18-Oct-01 1.1 E-03 9.2E-04 8.3E-04 0.7 0.8 24-Oct-01 8.3E-04 3.9E-04 5.4E-05 0.1 0.5 25-Oct-01 1.1 E-03 2 .6E-03 1.OE-03 1.0 2.5 26-Oct-01 8.9E-04 7.0E-04 1.1 E-03 1.2 0.8 27-Oct-01 1.OE-03 2 .2E-05 1.2E-03 1.2 0.0 28-Oct-01 9.0E-04 -1 .2E-03 1.7E-03 1.9 -1.3 29-Oct-01 9.3E-04 1.8E-03 9.0E-04 1.0 1.9 30-Oct-01 9.3E-04 2 .3E-03 9.1E-04 1.0 2.4 31-Oct-01 9.1E-04 3.0E-04 7.4E-04 0.8 0.3 134 A P P E N D I X D Date PO4 -P In-Reactor N H 4 - N In-Reactor Feed gives Recycle gives Total Feed gives Recycle gives Total (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) 2-Sep-01 1.8 5.2 7.0 50 182 232 4-Sep-01 1.7 6.2 7.9 58 200 258 5-Sep-01 1.8 4.7 6.5 62 184 246 6-Sep-01 1.9 4.5 6.4 64 164 227 7-Sep-01 3.4 6.1 9.4 83 178 261 13-Sep-01 2.5 5.8 8.3 67 189 256 14-Sep-01 2.4 5.7 8.1 65 202 267 15-Sep-01 2.8 5.5 8.2 69 181 251 16-Sep-01 3.5 12.4 15.8 90 193 283 17-Sep-01 3.0 7.8 10.8 70 169 239 18-Sep-01 2.9 6.7 9.6 72 182 254 19-Sep-01 3.0 6.7 9.6 59 174 233 20-Sep-01 2.7 6.5 9.2 64 203 267 21-Sep-01 3.4 5.5 8.9 83 183 266 22-Sep-01 4.5 9.0 13.5 98 171 268 23-Sep-01 3.9 7.0 10.9 88 179 267 24-Sep-01 3.8 11.1 14.9 85 132 216 2-Oct-01 3.5 5.9 9.4 83 180 263 3-Oct-01 3.1 5.3 8.4 70 171 241 5-Oct-01 5.6 12.5 18.1 81 164 246 10-Oct-01 5.6 4.8 10.3 83 158 241 11-Oct-01 13.3 17.7 31.0 77 167 244 12-Oct-01 7.0 10.4 17.3 49 197 247 13-Oct-01 7.0 8.8 15.8 46 199 245 14-Oct-01 7.7 7.6 15.3 50 200 250 15-Oct-OI 10.7 9.8 20.6 66 207 273 16-Oct-OI 9.5 8.5 18.0 62 203 265 17-Oct-01 7.6 7.2 14.8 49 222 271 18-Oct-01 9.2 9.7 18.9 53 207 261 24-Oct-OI 9.3 14.3 23.6 61 220 281 25-Oct-OI 8.9 6.1 15.0 61 188 249 26-Oct-01 6.9 4.6 11.5 53 199 252 27-Oct-OI 7.7 5.1 12.8 52 213 265 28-Oct-01 7.0 6.8 13.8 43 191 234 29-Oct-01 7.3 5.2 12.4 53 185 238 30-Oct-01 7.4 5.0 12.4 54 179 234 31-Oct-01 9.0 8.8 17.8 58 194 252 135 A P P E N D I X D Date M g In-Reactor In-Reactor Concentrations In-Reacor M g : P In-Reactor N:P Feed gives Recycle gives Total P 0 4 _ P N H 4 - N M g (molar ratio) (molar ratio) (mg/L) (mg/L) (mg/L) (mol/L) (mol/L) (mol/L) 2-Sep-01 19.3 73.1 92.4 2.3E-04 1.7E-02 3.8E-03 76.8 73.2 4-Sep-01 21.0 69.2 90.2 2.5E-04 1.8E-02 3.7E-03 14.6 72.6 5-Sep-01 23.8 63.9 87.7 2.1E-04 1.8E-02 3.6E-03 17.2 83.6 6-Sep-01 21.5 0.0 21.5 2.1E-04 1.6E-02 8.8E-04 4.3 78.9 7-Sep-01 23.3 44.4 67.7 3.0E-04 1.9E-02 2.8E-03 9.1 61.1 13-Sep-01 14.2 44.1 58.3 2.7E-04 1.8E-02 2.4E-03 9.0 68.5 14-Sep-01 14.1 41.9 56.0 2.6E-04 1.9E-02 2.3E-03 8.8 72.5 15-Sep-01 17.9 50.5 68.4 2.7E-04 1.8E-02 2.8E-03 10.6 67.4 16-Sep-01 18.6 45.4 64.0 5.1E-04 2.0E-02 2.6E-03 5.2 39.5 17-Sep-01 20.5 56.3 76.8 3.5E-04 1.7E-02 3.2E-03 9.1 49.1 18-Sep-01 17.6 46.9 64.5 3.1E-04 1.8E-02 2.7E-03 8.6 58.6 19-Sep-01 17.9 51.1 69.0 3.1E-04 1.7E-02 2.8E-03 9.1 53.5 20-Sep-01 17.9 53.4 71.3 3.0E-04 1.9E-02 2.9E-03 9.9 64.4 21-Sep-01 18.2 52.0 70.2 2.9E-04 1.9E-02 2.9E-03 10.0 65.9 22-Sep-01 4.1 16.8 20.9 4.4E-04 1.9E-02 8.6E-04 2.0 44.0 23-Sep-01 18.7 51.8 70.5 3.5E-04 1.9E-02 2.9E-03 8.2 54.1 24-Sep-01 17.9 78.0 95.9 4.8E-04 1.5E-02 3.9E-03 8.2 32.1 2-Oct-01 20.7 54.2 74.9 3.0E-04 1.9E-02 3.1 E-03 10.1 61.7 3-Oct-01 20.5 62.1 82.6 2.7E-04 1.7E-02 3.4E-03 12.5 63.3 5-Oct-01 20.8 40.5 61.3 5.9E-04 1.8E-02 2.5E-03 4.3 29.9 10-Oct-01 21.1 36.1 57.2 3.3E-04 1.7E-02 2.4E-03 7.1 51.5 11-Oct-01 21.3 25.5 46.8 1.OE-03 1.7E-02 1.9E-03 1.9 17.4 12-Oct-01 14.9 52.5 67.3 5.6E-04 1.8E-02 2 .8E-03 4.9 31.5 13-Oct-01 9.5 40.6 50.1 5.1E-04 1.8E-02 2.1 E-03 4.0 34.3 14-Oct-01 9.4 36.6 46.0 4 .9E-04 1.8E-02 1.9E-03 3.8 36.1 15-Oct-01 14.8 25.9 40.7 6.6E-04 2.0E-02 1.7E-03 2.5 29.4 16-Oct-01 14.1 29.1 43.2 5.8E-04 1.9E-02 1.8E-03 3.1 32.5 17-Oct-01 11.3 34.6 45.8 4 .8E-04 1.9E-02 1.9E-03 4.0 40.6 18-Oct-01 10.1 24.8 34.8 6.1E-04 1.9E-02 1.4E-03 2.4 30.5 24-Oct-01 4.0 13.6 17.6 7.6E-04 2.0E-02 7.2E-04 0.9 26.3 25-Oct-01 13.9 30.1 44.0 4 .8E-04 1.8E-02 1.8E-03 3.7 36.8 26-Oct-01 14.3 34.5 48.8 3.7E-04 1.8E-02 2 .0E-03 5.4 48.6 27-Oct-01 14.7 35.5 50.2 4 .1E-04 1.9E-02 2.1 E-03 5.0 45.8 28-Oct-01 14.8 28.3 43.1 4 .5E-04 1.7E-02 1.8E-03 4.0 37.5 29-Oct-01 14.3 38.1 52.4 4 .0E-04 1.7E-02 2 .2E-03 5.4 42.4 30-Oct-01 14.7 37.9 52.6 4 .0E-04 1.7E-02 2 .2E-03 5.4 41.8 31-Oct-01 13.8 33.2 47.1 5.7E-04 1.8E-02 1.9E-03 3.4 31.4 136 A P P E N D I X D Date Feed P s In-Reactor P s Equi l ibr ium P s Feed In-Reactor Effluent Crystal Harvest S.S. ratio S.S. Ratio S.S. Ratio Volume Volume (1) (1) 2-Sep-01 1.5E-08 1.4E-08 5.7E-09 2.6 2.5 2.5 4-Sep-01 1.4E-08 1.7E-08 4.9E-09 2.9 3.5 3.7 5-Sep-01 1.5E-08 1.3E-08 5.7E-09 2.6 2.3 2.2 6-Sep-01 1.5E-08 3.0E-09 5.7E-09 2.6 0.5 0.0 7-Sep-01 1.9E-08 1.6E-08 5.7E-09 3.3 2.8 2.5 1.00 13-Sep-01 1.3E-08 1.2E-08 3.0E-09 4.3 4.0 3.8 1.20 14-Sep-01 1.4E-08 1.2E-08 3.3E-09 4.2 3.5 3.2 1.40 15-Sep-01 1.6E-08 1.3E-08 3.3E-09 4.9 4.0 3.7 1.50 16-Sep-01 2.0E-08 2.7E-08 2.3E-07 0.1 0.1 0.1 1.00 17-Sep-01 1.9E-08 1.9E-08 6.7E-09 2.8 2.8 2.8 1.20 18-Sep-01 1.6E-08 1.5E-08 6.7E-09 2.4 2.2 2.2 1.30 19-Sep-01 1.7E-08 1.5E-08 4.3E-09 3.9 3.4 3.2 1.40 20-Sep-01 2.0E-08 1.7E-08 3.8E-09 5.2 4.4 4.2 1.60 21-Sep-01 1.6E-08 1.6E-08 3.8E-09 4.2 4.2 4.1 1.75 22-Sep-01 3.9E-09 7.2E-09 3.8E-09 1.1 1.9 2.4 1.40 23-Sep-01 1.7E-08 1.9E-08 3.8E-09 4.6 5.2 5.4 1.60 24-Sep-01 1.6E-08 2.9E-08 3.3E-09 4.9 8.8 10.5 2.10 2-Oct-01 2.0E-08 1.8E-08 3.3E-09 6.1 5.3 4.9 0.40 3-Oct-01 1.8E-08 1.6E-08 3.3E-09 5.5 4.8 4.4 0.53 5-Oct-01 2.3E-08 2.6E-08 4.3E-09 5.5 6.1 6.4 0.65 10-Oct-01 2.6E-08 1.3E-08 3.3E-09 7.8 4.1 2.6 0.50 11-Oct-01 5.7E-08 3.4E-08 3.3E-09 17.2 10.1 7.2 1.00 12-Oct-01 8.8E-08 2.7E-08 5.7E-09 15.3 4.8 3.2 1.50 13-Oct-01 5.2E-08 1.8E-08 5.7E-09 9.1 3.2 2.1 3.50 14-Oct-OI 5.2E-08 1.7E-08 5.7E-09 9.1 2.9 1.7 2.60 15-Oct-01 6.8E-08 2.2E-08 5.7E-09 12.0 3.8 2.0 3.30 16-Oct-01 7.1E-08 2.0E-08 5.7E-09 12.5 3.4 1.8 3.95 17-Oct-01 6 .9E-08 1.7E-08 4 .9E-09 14.1 3.5 1.9 4.50 18-Oct-01 6 .1E-08 1.6E-08 4 .9E-09 12.4 3.3 1.9 4.00 24-Oct-01 2 .2E-08 1 .1E-08 5.7E-09 3.9 1.9 1.5 3.80 25-Oct-01 6 .7E-08 1.6E-08 5.7E-09 11.8 2.7 1.2 4.45 26-Oct-01 5.8E-08 1.3E-08 5.7E-09 10.1 2.3 1.0 5.10 27-Oct-01 7.3E-08 1.6E-08 5.7E-09 12.7 2.8 1.2 5.75 28-Oct-01 5.8E-08 1.3E-08 5.7E-09 10.2 2.3 1.2 5.70 29-Oct-01 6 .0E-08 1.5E-08 5.7E-09 10.5 2.6 1.2 6.35 30-Oct-01 6 .1E-08 1.4E-08 5.7E-09 10.6 2.5 1.1 5.60 31-Oct-01 5.8E-08 2.0E-08 6.7E-09 8.7 3.0 1.7 6.25 137 A P P E N D I X D Date C R T C R T Averaged Harvested Product Data Actual In reactor > 2 mm > 1 mm > 0.5 mm < 0.5 mm Total Mass (days) SS Ratio (g) (g) (g) (g) (g) 2-Sep-01 4- Sep-01 5- Sep-01 6- Sep-01 7- Sep-01 13- Sep-01 14- Sep-01 15- Sep-01 16- Sep-01 17- Sep-01 18- Sep-01 19- Sep-01 20- Sep-01 21- Sep-01 22- Sep-01 23- Sep-01 24- Sep-01 2- Oct-01 3- Oct-01 5-Oct-01 10- Oct-01 11- Oct-01 12- Oct-01 13- Oct-01 14- Oct-01 15- Oct-01 16- Oct-01 17- Oct-01 18- Oct-01 24- Oct-01 25- Oct-01 26- Oct-01 27- Oct-01 28- Oct-01 29- Oct-01 30- Oct-01 31 - Oct-01 12 28 3.9 1.5 5.3 6.1 7.4 20.2 33 35 37 3.7 3.6 3.6 0.2 7.6 24.5 23.1 1.3 62.6 106.6 87.7 41.8 170.1 77.5 66.0 55.3 258.1 355.4 138 A P P E N D I X D Date Harvested Product Data Mass P Theoretical % > 2 m m % 1-2 mm % 0.5-1 mm % < 0.5mm M e a n Crysta l Removed Mass M A P Size (mm) (g) G r o w n (g) 2-Sep-01 1.6 12.4 4-Sep-01 -1.2 -9.9 5-Sep-01 1.1 9.1 6-Sep-01 1.9 14.8 7-Sep-01 2.6 20.7 13-Sep-01 2.4 18.7 14-Sep-01 2.7 21.5 15-Sep-01 3.7 29.2 16-Sep-01 -11.2 -88.6 17-Sep-01 -0.1 -0.7 18-Sep-01 1.5 12.0 19-Sep-01 3.2 25.2 20-Sep-01 3.0 24.1 21-Sep-01 4.8 38.3 22-Sep-01 -2.1 -16.6 23-Sep-01 2.8 22.2 24-Sep-01 -8.3 -65.7 2-Oct-01 4.9 38.6 3-Oct-01 5.2 41.2 5-Oct-01 -4.2 -33.0 10-Oct-01 17.0 134.4 11-Oct-01 24.3 192.6 12-Oct-01 23.9 189.6 13-Oct-01 25.7 203.5 14-Oct-01 29.9 237.0 15-Oct-01 41.4 327.9 16-Oct-01 37.2 294.4 17-Oct-01 7.3 26.1 30.2 36.5 20.7 163.7 18-Oct-01 35.6 282.1 24-Oct-01 28.8 227.8 25-Oct-01 36.6 289.9 26-Oct-01 29.5 233.2 27-Oct-01 0.4 13.7 44.2 41.7 0.7 32.7 259.0 28-Oct-01 27.8 220.2 29-Oct-01 0.5 24.3 41.3 34.0 0.8 30.7 243.0 30-Oct-01 31.3 247.6 31-Oct-01 11.8 47.9 21.8 18.6 1.2 33.5 265.5 139 A P P E N D I X D Date Notes 2-Sep-01 4- Sep-01 5- Sep-01 6- Sep-01 7- Sep-01 13- Sep-01 No Plugging 14- Sep-01 pH controller malfunction, ph up to 11 15- Sep-01 pH probe out of calibration, caustic inlet plugged 16- Sep-01 pH controller set to acid 17- Sep-01 18- Sep-01 19- Sep-01 20- Sep-01 21- Sep-01 22- Sep-01 Mg feed off 23- Sep-01 Effluent Plugged 24- Sep-01 Power Failure + Seed hopper fitting broke off 2- Oct-01 3- Oct-01 5-Oct-01 10- Oct-01 11- Oct-01 12- Oct-01 13- Oct-01 14- Oct-01 15- Oct-01 16- Oct-01 17- Oct-01 18- Oct-01 24- Oct-01 25- Oct-01 26- Oct-01 27- Oct-01 28- Oct-01 29- Oct-01 30- Oct-01 3 1 - Oct-01 140 A P P E N D I X D Date M g C l Feed Supernatant L a b results Effluent L a b results P H M g PO4-P N H 4 . N M g PO4-P N H 4 . N M g (mg/1) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) 1-Nov-OI 733 46.7 284 25.8 8.2 240 46.0 8.4 2-Nov-01 733 46.4 283 25.5 8.9 231 47.0 8.3 7-Nov-01 733 46.4 324 30.1 14.0 239 34.7 8.0 8-Nov-01 733 45.6 298 28.8 13.9 238 31.1 8.0 9-Nov-01 733 45.9 302 29.1 14.1 242 30.8 8.0 10-Nov-01 733 46.3 274 28.8 15.7 232 30.5 8.0 H -Nov -01 733 54.8 298 29.7 16.2 252 22.9 8.0 12-Nov-01 733 53.7 267 30.7 14.2 220 22.6 8.0 13-NOV-01 733 54.8 284 29.4 16.9 257 27.4 8.0 14-NOV-01 495 53.0 304 32.4 27.0 282 37.9 7.7 15-Nov-01 495 51.9 299 30.6 23.5 270 37.8 7.8 16-Nov-01 495 51.9 299 30.6 23.5 270 37.8 7.8 17-Nov-01 495 51.9 299 30.6 23.5 270 37.8 7.8 18-Nov-01 495 51.9 273 29.3 24.8 255 37.4 7.7 19-Nov-01 495 61.2 197 30.3 43.6 194 18.0 7.8 20-Nov-01 495 59.8 354 28.3 29.4 313 29.8 7.8 21-Nov-01 495 64.0 365 28.9 33.2 330 29.3 7.8 22-Nov-01 495 63.7 360 27.1 29.8 320 28.9 7.8 23-Nov-01 495 61.5 369 29.9 31.3 321 32.6 7.8 24-Nov-01 623 60.2 356 27.1 28.0 321 35.4 7.7 25-Nov-OI 623 60.2 356 27.1 28.0 321 35.4 7.7 26-Nov-01 623 60.2 356 27.1 28.0 321 35.4 7.7 27-Nov-01 623 61.5 354 26.3 26.4 317 36.3 7.7 28-Nov-01 623 60.6 366 27.3 27.2 334 36.2 7.7 29-Nov-01 623 61.7 346 28.2 25.6 311 33.5 7.8 30-Nov-01 623 58.5 359 25.7 24.2 326 32.2 7.8 1-Dec-01 623 65.2 380 26.3 34.1 335 36.6 7.7 2-Dec-01 623 68.1 406 26.0 35.1 360 36.1 7.6 3-Dec-01 623 67.2 391 26.1 32.6 339 34.1 7.6 4-Dec-01 623 69.2 436 24.9 26.3 359 32.7 7.7 5-Dec-01 616 69.1 400 29.5 34.2 378 35.2 7.6 6-Dec-01 616 68.2 398 25.4 34.1 358 33.9 7.7 7-Dec-01 616 71.1 399 25.4 30.4 351 33.6 7.6 8-Dec-01 616 71.1 399 25.4 30.4 351 33.6 7.6 9-Dec-01 616 71.1 399 25.4 30.4 351 33.6 7.6 10-Dec-01 616 71.1 399 25.4 30.4 351 33.6 7.6 11-Dec-01 616 71.2 409 23.7 30.3 395 32.2 7.6 12-Dec-01 616 65.7 426 29.4 28.9 442 31.8 7.6 13-Dec-01 616 64.6 399 30.6 33.3 362 32.6 7.6 ) c t 1 2 - D e c 13 Average 647 55.1 330 26.8 21.4 291 35.6 8.0 Min imum 495 37.2 197 11.1 5.8 194 17.3 7.6 Max imum 792 71.2 436 35.1 43.6 442 63.8 8.5 St .Dev. 96 10.3 53 4.5 10.0 54 7.8 0.3 Count 55 55 55 55 55 55 55 55 141 A P P E N D I X D Date M g C l Caustic Total Supernatant Recycle Tota l flow Flow Flow Influent Flow Flow Flow (influent+recycle) (mL/min) (1/day) (mL/min) (mL/min) (mL/min) (mL/min) 1-NOV-01 43 65 725 637 2925 3650 2-NOV-01 42 70 730 639 2920 3650 7-NOV-01 42 30 710 647 2890 3600 8-NOV-01 42 40 700 630 2850 3550 9-NOV-01 40 47.5 710 637 2840 3550 10-NOV-01 40 25 700 643 2875 3575 11-NOV-01 39 25 800 744 2875 3675 12-NOV-01 39 30 810 750 2890 3700 13-NOV-01 38 30 720 661 2880 3600 14-NOV-01 40 37.5 690 624 2910 3600 15-NOV-01 37 30 680 622 2890 3570 16-NOV-01 37 30 670 612 2870 3540 17-NOV-01 37 30 660 602 2850 3510 18-NOV-01 37 15 630 583 2870 3500 19-NOV-01 0 30 550 529 3100 3650 20-NOV-01 38 17.5 650 600 3100 3750 21-NOV-01 39 42.5 760 691 2890 3650 22-NOV-01 39 45 710 640 2840 3550 23-NOV-01 38 25 740 685 2810 3550 24-NOV-01 37 40 720 655 2780 3500 25-NOV-01 37 40 720 655 2780 3500 26-Nov-01 37 40 720 655 2780 3500 27-Nov-01 37 30 700 642 2800 3500 28-Nov-01 40 25 710 653 2790 3500 29-Nov-01 36 30 600 543 2950 3550 30-Nov-01 34 27.5 590 537 2960 3550 1-Dec-01 34 30 600 545 3000 3600 2-Dec-01 32 32.5 600 545 3000 3600 3-Dec-01 33 40 590 529 3010 3600 4-Dec-01 33 70 610 528 2990 3600 5-Dec-01 32 20 570 524 2980 3550 6-Dec-01 32 20 575 529 3000 3575 7-Dec-01 35 1.25 590 554 2910 3500 8-Dec-01 35 1.25 590 554 2910 3500 9-Dec-01 35 1.25 590 554 2910 3500 10-Dec-01 35 1.25 590 554 2910 3500 11-Dec-01 35 30 570 514 2990 3560 12-Dec-01 35 15 540 495 3060 3600 13-Dec-01 34 30 560 505 3015 3575 )ct 12-Dec 13 Average 37 30 676 618 2882 3557 Min imum 0 1.25 430 396 1970 2400 Max imum 58 95 930 884 3100 3800 St. Dev. 11 18 90 84 148 174 Count 55 55 55 55 55 55 142 A P P E N D I X D Date Conditions at the inlet Removal efficiency (%) PO 4_P (mg/L) N H 4 - N (mg/L) M g (mg/L) PO 4 -P N H 4 . N M g 1-Nov-Oi 41.0 249 66.1 80 4 30 2-Nov-OI 40.6 248 64.5 78 7 27 7-Nov-01 42.3 295 70.8 67 19 51 8-Nov-01 41.1 268 69.9 66 11 56 9-Nov-01 41.2 271 67.4 66 11 54 10-Nov-01 42.5 252 68.3 63 8 55 11-Nov-01 50.9 277 63.3 68 9 64 12-Nov-01 49.7 247 63.7 71 11 65 13-Nov-01 50.3 261 65.7 66 1 58 14-Nov-01 47.9 275 58.0 44 -3 35 15-Nov-01 47.5 274 54.9 51 1 31 16-Nov-01 47.4 273 55.3 50 1 32 17-Nov-01 47.4 273 55.6 50 1 32 18-Nov-01 48.0 252 56.1 48 -1 33 19-Nov-01 58.9 190 29.2 26 -2 38 20-Nov-01 55.2 327 55.0 47 4 46 21-Nov-01 58.2 332 51.7 43 1 43 22-Nov-01 57.4 324 51.6 48 1 44 23-Nov-OI 56.9 341 53.1 45 6 39 24-Nov-01 54.7 324 56.7 49 1 38 25-Nov-01 54.7 324 56.7 49 1 38 26-Nov-01 54.7 324 56.7 49 1 38 27-Nov-01 56.4 325 57.1 53 2 36 28-Nov-01 55.7 336 60.2 51 1 40 29-Nov-01 55.9 313 62.9 54 1 47 30-NOV-01 53.2 327 59.3 55 0 46 1-Dec-01 59.2 345 59.2 42 3 38 2-Dec-01 61.9 369 56.9 43 2 37 3-Dec-01 60.3 351 58.3 46 3 41 4-Dec-01 59.9 378 55.3 56 5 41 5-Dec-01 63.5 368 61.7 46 -3 43 6-Dec-01 62.7 366 57.6 46 2 41 7-Dec-01 66.7 375 60.4 54 6 44 8-Dec-01 66.7 375 60.4 54 6 44 9-Dec-01 66.7 375 60.4 54 6 44 10-Dec-01 66.7 375 60.4 54 6 44 11-Dec-01 64.2 369 59.2 53 -7 46 12-Dec-01 60.1 390 66.8 52 -13 52 13-Dec-01 58.2 360 65.0 43 -1 50 )ct 12-Dec 13 Average 50.5 301 60.0 60 4 40 Min imum 33.4 190 18.6 26 -13 7 Max imum 66.7 390 83.9 84 19 65 St .Dev. 9.6 48 9.9 14 6 12 Count 55 55 55 55 55 55 143 A P P E N D I X D Date M o l a r removal M g : P N :P Inlet to outlet Removal Removal PO4 . .P N H 4 - N M g Ratio Ratio 1-NOV-01 1.1 E-03 6.8E-04 8.3E-04 0.8 0.6 2-NOV-01 1.OE-03 1.2E-03 7.2E-04 0.7 1.2 7-NOV-01 9.1E-04 4 .0E-03 1.5E-03 1.6 4.4 8-NOV-01 8.8E-04 2 .2E-03 1.6E-03 1.8 2.5 9-NOV-01 8.7E-04 2.1 E-03 1.5E-03 1.7 2.4 10-NOV-01 8.7E-04 1.4E-03 1.6E-03 1.8 1.6 11-NOV-01 1.1 E-03 1.8E-03 1.7E-03 1.5 1.6 12-NOV-01 1.1 E-03 1.9E-03 1.7E-03 1.5 1.7 13-NOV-01 1.1 E-03 2.7E-04 1.6E-03 1.5 0.3 14-NOV-01 6.8E-04 -5.1E-04 8.3E-04 1.2 -0.8 15-NOV-01 7.7E-04 2.6E-04 7.0E-04 0.9 0.3 16-NOV-01 7.7E-04 2.3E-04 7.2E-04 0.9 0.3 17-NOV-01 7.7E-04 2 .0E-04 7.3E-04 1.0 0.3 18-NOV-01 7.5E-04 -1.8E-04 7.7E-04 1.0 -0.2 19-NOV-01 4 .9E-04 -3.2E-04 4 .6E-04 0.9 -0.6 20-NOV-01 8.3E-04 9.8E-04 1.OE-03 1.2 1.2 21-NOV-01 8.1E-04 1.5E-04 9.2E-04 1.1 0.2 22-NOV-01 8.9E-04 3.1E-04 9.3E-04 1.0 0.4 23-NOV-01 8.3E-04 1.5E-03 8.4E-04 1.0 1.8 24-NOV-01 8.6E-04 2.1E-04 8.8E-04 1.0 0.2 25-NOV-01 8.6E-04 2.1E-04 8.8E-04 1.0 0.2 26-Nov-01 8.6E-04 2 .1E-04 8.8E-04 1.0 0.2 27-Nov-01 9.7E-04 5.5E-04 8.5E-04 0.9 0.6 28-Nov-01 9.2E-04 1.7E-04 9.9E-04 1.1 0.2 29-Nov-01 9.8E-04 1.6E-04 1.2E-03 1.2 0.2 30-Nov-01 9.4E-04 4 .9E-05 1.1 E-03 1.2 0.1 1-Dec-01 8.1E-04 7.3E-04 9.3E-04 1.1 0.9 2-Dec-01 8.6E-04 6.5E-04 8.5E-04 1.0 0.8 3-Dec-01 8.9E-04 8.4E-04 9.9E-04 1.1 0.9 4-Dec-01 1.1 E-03 1.3E-03 9.3E-04 0.9 1.2 5-Dec-01 9.5E-04 -7.3E-04 1.1 E-03 1.1 -0.8 6-Dec-01 9.3E-04 5.9E-04 9.8E-04 1.1 0.6 7-Dec-01 1.2E-03 1.7E-03 1.1 E-03 0.9 1.4 8-Dec-01 1.2E-03 1.7E-03 1.1 E-03 0.9 1.4 9-Dec-01 1.2E-03 1.7E-03 1.1 E-03 0.9 1.4 10-Dec-01 1.2E-03 1.7E-03 1.1 E-03 0.9 1.4 11-Dec-01 1.1 E-03 -1 .9E-03 1.1 E-03 1.0 -1.7 12-Dec-01 1.OE-03 -3 .7E-03 1.4E-03 1.4 -3.7 13-Dec-01 8.1E-04 -1.5E-04 1.3E-03 1.7 -0.2 ) c t 1 2 - D e c 1 3 Average 9.4E-04 7.2E-04 1.OE-03 1.1 0.7 Minimum 4 .9E-04 -3 .7E-03 5.4E-05 0.1 -3.7 Max imum 1.2E-03 4 .0E-03 1.7E-03 1.9 4.4 St. Dev. 1.4E-04 1.2E-03 3.5E-04 0.4 1.2 Count 55 55 55 55 55 144 A P P E N D I X D Date PO4 -P In-Reactor N H 4 - N In-Reactor Feed gives Recycle gives Total Feed gives Recycle gives Tota l (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) 1-NOV-01 8.1 6.6 14.7 50 192 242 2-NOV-01 8.1 7.1 15.2 50 185 234 7-NOV-01 8.3 11.2 19.6 58 192 250 8-NOV-01 8.1 11.2 19.3 53 191 244 9-NOV-01 8.2 11.3 19.5 54 194 248 10-NOV-01 8.3 12.6 20.9 49 187 236 11-NOV-01 11.1 12.7 23.8 60 197 257 12-NOV-01 10.9 11.1 22.0 54 172 226 13-NOV-01 10.1 13.5 23.6 52 206 258 14-Nov-Oi 9.2 21.8 31.0 53 228 281 15-Nov-01 9.0 19.0 28.1 52 219 271 16-Nov-01 9.0 19.1 28.0 52 219 271 17-Nov-01 8.9 19.1 28.0 51 219 271 18-Nov-01 8.6 20.3 29.0 45 209 255 19-Nov-01 8.9 37.0 45.9 29 165 193 20-Nov-01 9.6 24.3 33.9 57 259 315 21-Nov-01 12.1 26.3 38.4 69 261 330 22-Nov-01 11.5 23.8 35.3 65 256 321 23-Nov-Oi 11.9 24.7 36.6 71 254 325 24-Nov-01 11.3 22.2 33.5 67 255 322 25-Nov-01 11.3 22.2 33.5 67 255 322 26-Nov-01 11.3 22.2 33.5 67 255 322 27-Nov-01 11.3 21.1 32.4 65 254 319 28-Nov-01 11.3 21.6 32.9 68 266 334 29-Nov-01 9.4 21.2 30.7 53 258 311 30-Nov-01 8.8 20.1 29.0 54 272 326 1-Dec-OI 9.9 28.4 38.3 58 279 337 2-Dec-01 10.3 29.3 39.6 62 300 362 3-Dec-01 9.9 27.3 37.1 57 283 341 4-Dec-01 10.1 21.8 32.0 64 298 362 5-Dec-01 10.2 28.7 38.9 59 317 376 6-Dec-01 10.1 28.6 38.7 59 300 359 7-Dec-01 11.2 25.3 36.5 63 292 355 8-Dec-01 11.2 25.3 36.5 63 292 355 9-Dec-01 11.2 25.3 36.5 63 292 355 10-Dec-01 11.2 25.3 36.5 63 292 355 11-Dec-01 10.3 25.4 35.7 59 332 391 12-Dec-01 9.0 24.6 33.6 59 376 434 13-Dec-01 9.1 28.0 37.2 56 305 362 let 12-Dec 13 Average 9.5 17.5 26.9 57 237 293 Min imum 6.9 4.6 11.5 29 165 193 Max imum 12.1 37.0 45.9 71 376 434 S t D e v . 1.5 8.4 9.4 8 48 52 Count 55 55 55 55 55 55 145 A P P E N D I X D Date M g In-Reactor In-Reactor Concentrations In-Reacor M g : P In-Reactor N:P Feed gives Recycle gives Total P 0 4 _ P N H 4 - N M g (molar ratio) (molar ratio) (mg/L) (mg/L) (mg/L) (mol/L) (mol/L) (mol/L) 1-NOV-01 13.1 36.9 50.0 4 .8E-04 1.7E-02 2.1 E-03 4.3 36.4 2-NOV-01 12.9 37.6 50.5 4 .9E-04 1.7E-02 2.1 E-03 4.2 34.0 7-NOV-01 14.0 27.9 41.8 6.3E-04 1.8E-02 1.7E-03 2.7 28.3 8-NOV-01 13.8 25.0 38.8 6.2E-04 1.7E-02 1.6E-03 2.6 28.0 9-NOV-01 13.5 24.6 38.1 6.3E-04 1.8E-02 1.6E-03 2.5 28.1 10-NOV-01 13.4 24.5 37.9 6.8E-04 1.7E-02 1.6E-03 2.3 24.9 11-NOV-01 13.8 17.9 31.7 7.7E-04 1.8E-02 1.3E-03 1.7 24.0 12-NOV-01 13.9 17.7 31.6 7.1E-04 1.6E-02 1.3E-03 1.8 22.7 13-NOV-01 13.1 21.9 35.1 7.6E-04 1.8E-02 1.4E-03 1.9 24.2 14-NOV-01 11.1 30.6 41.7 1.OE-03 2.0E-02 1.7E-03 1.7 20.0 15-NOV-01 10.5 30.6 41.1 9.1E-04 1.9E-02 1.7E-03 1.9 21.3 16-NOV-01 10.5 30.6 41.1 9.0E-04 1.9E-02 1.7E-03 1.9 21.4 17-NOV-01 10.5 30.7 41.2 9.0E-04 1.9E-02 1.7E-03 1.9 21.4 18-NOV-01 10.1 30.7 40.8 9.4E-04 1.8E-02 1.7E-03 1.8 19.4 19-NOV-01 4.4 15.3 19.7 1.5E-03 1.4E-02 8.1E-04 0.5 9.3 20-NOV-01 9.5 24.6 34.2 1.1 E-03 2 .3E-02 1.4E-03 1.3 20.6 21-NOV-01 10.8 23.2 34.0 1.2E-03 2 .4E-02 1.4E-03 1.1 19.0 22-NOV-01 10.3 23.1 33.4 1.1 E-03 2 .3E-02 1.4E-03 1.2 20.1 23-NOV-01 11.1 25.8 36.9 1.2E-03 2 .3E-02 1.5E-03 1.3 19.7 24-NOV-01 11.7 28.1 39.8 1.1 E-03 2 .3E-02 1.6E-03 1.5 21.3 25-NOV-01 11.7 28.1 39.8 1.1 E-03 2 .3E-02 1.6E-03 1.5 21.3 26-Nov-01 11.7 28.1 39.8 1.1 E-03 2 .3E-02 1.6E-03 1.5 21.3 27-Nov-01 11.4 29.0 40.5 1.OE-03 2.3E-02 1.7E-03 1.6 21.8 28-Nov-01 12.2 28.9 41.1 1.1 E-03 2 .4E-02 1.7E-03 1.6 22.5 29-Nov-01 10.6 27.8 38.5 9.9E-04 2 .2E-02 1.6E-03 1.6 22.5 30-Nov-01 9.9 26.8 36.7 9.4E-04 2 .3E-02 1.5E-03 1.6 24.9 1-Dec-01 9.9 30.5 40.4 1.2E-03 2 .4E-02 1.7E-03 1.3 19.5 2-Dec-01 9.5 30.1 39.6 1.3E-03 2 .6E-02 1.6E-03 1.3 20.2 3-Dec-01 9.5 28.5 38.1 1.2E-03 2 .4E-02 1.6E-03 1.3 20.3 4-Dec-01 9.4 27.2 36.5 1.OE-03 2 .6E-02 1.5E-03 1.5 25.1 5-Dec-01 9.9 29.6 39.5 1.3E-03 2 .7E-02 1.6E-03 1.3 21.4 6-Dec-01 9.3 28.4 37.7 1.2E-03 2 .6E-02 1.6E-03 1.2 20.6 7-Dec-01 10.2 27.9 38.1 1.2E-03 2 .5E-02 1.6E-03 1.3 21.5 8-Dec-01 10.2 27.9 38.1 1.2E-03 2 .5E-02 1.6E-03 1.3 21.5 9-Dec-01 10.2 27.9 38.1 1.2E-03 2 .5E-02 1.6E-03 1.3 21.5 10-Dec-01 10.2 27.9 38.1 1.2E-03 2 .5E-02 1.6E-03 1.3 21.5 11-Dec-01 9.5 27.0 36.5 1.2E-03 2 .8E-02 1.5E-03 1.3 24.2 12-Dec-01 10.0 27.0 37.1 1.1 E-03 3.1 E-02 1.5E-03 1.4 28.6 13-Dec-01 10.2 27.5 37.7 1.2E-03 2 .6E-02 1.6E-03 1.3 21.5 ) c t 1 2 - D e c 1 3 Average 11.4 28.9 40.3 8.7E-04 2.1 E-02 1.7E-03 2.3 26.5 Min imum 4.0 13.6 17.6 3.7E-04 1.4E-02 7.2E-04 0.5 9.3 Max imum 14.9 52.5 67.3 1.5E-03 3.1 E-02 2 .8E-03 5.4 48.6 St .Dev. 2.4 6.3 7.6 3.0E-04 3 .7E-03 3.1E-04 1.3 7.9 Count 55 55 55 55 55 55 55 55 146 A P P E N D I X D Date Feed P s In-Reactor P s Equi l ibr ium P s Feed In-Reactor Effluent Crystal Harvest S.S. ratio S.S. Ratio S.S. Ratio Volume Volume (1) (1) 1-NOV-01 6.4E-08 1.7E-08 5.7E-09 11.2 3.0 1.5 5.80 2-NOV-01 6.2E-08 1.7E-08 6.7E-09 9.2 2.5 1.4 6.40 1.1 7-NOV-01 8.4E-08 1.9E-08 1.1E-08 7.3 1.7 1.0 5.80 8-NOV-01 7.3E-08 1.7E-08 1.1E-08 6.4 1.5 0.9 6.25 9-NOV-01 7.1E-08 1.7E-08 1.1E-08 6.2 1.5 0.9 6.80 1.1 10-NOV-01 6.9E-08 1.8E-08 1.1E-08 6.0 1.5 0.9 6.35 11-NOV-01 8.5E-08 1.8E-08 1.1E-08 7.4 1.6 0.8 7.00 12-NOV-01 7.4E-08 1.5E-08 1.1E-08 6.5 1.3 0.6 7.75 1.1 13-NOV-01 8.2E-08 2.0E-08 1.1E-08 7.1 1.8 1.0 7.30 14-NOV-01 7.2E-08 3.4E-08 2.1E-08 3.4 1.6 1.3 7.80 1.1 15-NOV-01 6.8E-08 3.0E-08 1.7E-08 3.9 1.7 1.3 7.20 16-NOV-01 6.8E-08 3.0E-08 1.7E-08 4.0 1.7 1.3 7.70 17-NOV-01 6.8E-08 3.0E-08 1.7E-08 4.0 1.7 1.3 8.25 18-NOV-01 6.5E-08 2 .9E-08 2 .1E-08 3.0 1.3 1.1 8.40 1.1 19-NOV-01 3.1E-08 1.7E-08 1.7E-08 1.8 1.0 0.8 7.65 20-NOV-01 9.4E-08 3.5E-08 1.7E-08 5.5 2.0 1.5 8.20 1.1 21-NOV-01 9.5E-08 4 .1E-08 1.7E-08 5.5 2.4 1.8 7.90 1.1 22-NOV-01 9.1E-08 3.6E-08 1.7E-08 5.3 2.1 1.5 7.10 23-NOV-01 9.8E-08 4 .2E-08 1.7E-08 5.7 2.4 1.8 7.30 1.1 24-NOV-01 9.5E-08 4 .1E-08 2.1E-08 4.5 1.9 1.4 7.50 25-NOV-01 9.5E-08 4 .1E-08 2.1E-08 4.5 1.9 1.4 7.70 26-Nov-01 9.5E-08 4 .1E-08 2.1E-08 4.5 1.9 1.4 7.80 1.1 27-Nov-01 9.9E-08 4 .0E-08 2.1E-08 4.7 1.9 1.3 6.90 28-Nov-01 1.1E-07 4 .3E-08 2.1E-08 5.0 2.0 1.5 7.55 1.1 29-Nov-01 1.0E-07 3.5E-08 1.7E-08 6.1 2.0 1.5 6.75 30-Nov-01 9.8E-08 3.3E-08 1.7E-08 5.7 1.9 1.4 7.00 1-Dec-01 1.1E-07 4 .9E-08 2 .1E-08 5.4 2.3 1.9 7.25 2-Dec-01 1.2E-07 5.4E-08 2 .7E-08 4.6 2.0 1.6 7.50 1.1 3-Dec-01 1.2E-07 4 .6E-08 2 .7E-08 4.4 1.7 1.3 6.65 4-Dec-01 1.2E-07 4 .0E-08 2.1E-08 5.6 1.9 1.4 7.00 5-Dec-01 1.4E-07 5.5E-08 2.7E-08 5.1 2.1 1.6 7.25 6-Dec-01 1.3E-07 5.0E-08 2.1E-08 5.9 2.3 1.8 7.45 1.1 7-Dec-01 1.4E-07 4 .7E-08 2.7E-08 5.4 1.8 1.3 8-Dec-01 1.4E-07 4 .7E-08 2.7E-08 5.4 1.8 1.3 9-Dec-01 1.4E-07 4 .7E-08 2.7E-08 5.4 1.8 1.3 10-Dec-01 1.4E-07 4 .7E-08 2.7E-08 5.4 1.8 1.3 7.40 11-Dec-01 1.3E-07 4 .8E-08 2 .7E-08 5.0 1.8 1.4 7.75 1.1 12-Dec-01 1.5E-07 5.1E-08 2 .7E-08 5.6 1.9 1.4 6.80 13-Dec-01 1.3E-07 4 .8E-08 2.7E-08 4.8 1.8 1.4 7.00 1.1 Oct 12-Dec 13 Average 8.8E-08 3.0E-08 1.5E-08 6.9 2.2 1.4 6.40 1.0 Min imum 2.2E-08 1.1E-08 4 .9E-09 1.8 1.0 0.6 1.50 0.3 Max imum 1.5E-07 5.5E-08 2 .7E-08 15.3 4.8 3.2 8.40 1.1 St .Dev. 3 .1E-08 1.4E-08 8.0E-09 3.1 0.7 0.4 1.58 0.3 Count 55 55 55 55 55 55 52 18 147 A P P E N D I X D Date C R T C R T Averaged Harvested Product Data Actual In reactor > 2 m m > 1 m m > 0.5 m m < 0.5 mm Total Mass (days) SS Ratio (g) (g) (g) (g) (g) 1-Nov-01 2-Nov-01 39 3.5 62.5 212.3 62.0 30.5 367.4 7-Nov-01 8-Nov-01 9-Nov-01 42 3.4 27.6 193.0 55.4 48.4 324.5 10-Nov-01 11-Nov-Oi 12-Nov-01 45 3.3 17.6 202.8 54.4 58.7 333.5 13-Nov-01 U -Nov -01 47 3.2 26.5 185.5 66.8 64.6 343.3 15-Nov-01 16-Nov-01 17-Nov-01 18-Nov-01 24 2.1 31.3 206.2 62.4 37.1 336.9 19-Nov-01 20-Nov-01 18 1.8 12.0 255.9 90.8 37.0 395.8 21-Nov-01 16 1.7 39.1 215.1 58.8 56.9 369.9 22-Nov-01 23-Nov-OI 13 1.7 55.5 219.5 50.4 63.7 389.1 24-Nov-OI 25-Nov-01 26-Nov-01 15 1.8 80.6 251.0 43.7 31.1 406.3 27-Nov-01 28-Nov-01 15 1.8 64.2 245.5 53.6 49.7 413.0 29-Nov-01 30-Nov-01 1-Dec-01 2-Dec-01 15 1.9 69.6 280.0 49.1 46.4 445.1 3-Dec-01 4-Dec-01 5-Dec-01 6-Dec-01 17 2.0 151.6 277.9 24.0 27.1 480.7 7-Dec-01 8-Dec-01 9-Dec-01 10-Dec-01 11-Dec-01 21 2.0 219.3 304.0 14.4 13.1 550.8 12-Dec-01 13-Dec-01 19 1.9 113.7 482.6 46.7 14.5 657.4 ct 12-Dec 13 Average 27 2.6 56.4 209.8 52.6 42.4 361.3 Minimum 13 1.7 0.2 5.3 6.1 7.4 20.2 Max imum 47 3.9 219.3 482.6 106.6 87.7 657.4 S t D e v . 12 0.8 57.0 109.8 25.2 21.6 148.6 Count 18 18 18 18 18 18 18 A P P E N D I X D Date Harvested Product Data Mass P Theoretical % > 2 m m % 1-2 mm % 0.5-1 m m % < 0.5mm M e a n Crysta l Removed Mass M A P Size (mm) (g) G r o w n l -Nov-01 34.3 271.4 2-Nov-01 17.0 57.8 16.9 8.3 1.4 33.4 264.2 7-Nov-01 28.9 229.1 8-Nov-01 27.4 216.8 9-Nov-01 8.5 59.5 17.1 14.9 1.3 27.7 219.3 10-Nov-01 27.0 214.0 11-Nov-01 40.0 316.9 12-Nov-01 5.3 60.8 16.3 17.6 1.2 41.4 328.2 13-Nov-OI 34.7 274.4 14-Nov-OI 7.7 54.0 19.5 18.8 1.2 20.8 164.7 15-Nov-01 23.5 186.0 16-Nov-01 23.1 182.8 17-Nov-01 22.7 179.5 18-Nov-01 9.3 61.2 18.5 11.0 1.3 21.0 166.6 19-Nov-01 12.1 95.9 20-Nov-01 3.0 . 64.7 22.9 9.4 1.2 24.1 191.1 21-Nov-01 10.6 58.2 15.9 15.4 1.3 27.4 216.9 22-Nov-01 28.2 223.5 23-Nov-01 14.3 56.4 13.0 16.4 1.3 27.3 216.1 24-Nov-01 27.8 220.0 25-Nov-01 27.8 220.0 26-Nov-01 19.8 61.8 10.8 7.6 1.5 27.8 220.0 27-Nov-01 30.3 240.0 28-Nov-01 15.5 59.4 13.0 12.0 1.4 29.1 230.8 29-Nov-01 26.2 207.4 30-Nov-01 24.7 195.7 1-Dec-01 21.7 172.0 2-Dec-01 15.6 62.9 11.0 10.4 1.4 23.1 183.1 3-Dec-01 23.5 186.2 4-Dec-01 29.6 234.1 5-Dec-01 24.0 190.4 6-Dec-01 31.5 57.8 5.0 5.6 1.7 23.7 187.9 7-Dec-01 30.9 244.5 8-Dec-01 30.9 244.5 9-Dec-01 30.9 244.5 10-Dec-01 30.9 244.5 11-Dec-01 39.8 55.2 2.6 2.4 1.8 27.8 220.2 12-Dec-01 24.3 192.3 13-Dec-01 17.3 73.4 7.1 2.2 1.6 20.1 159.5 O c t 1 2 - D e c 1 3 Average 13.1 53.1 18.2 15.7 1.3 28.2 223.7 Minimum 0.4 13.7 2.6 2.2 0.7 12.1 95.9 Max imum 39.8 73.4 44.2 41.7 1.8 41.4 328.2 St. Dev. 10.1 15.6 11.1 11.2 0.3 5.6 44.5 Count 18 18 18 18 17 55 55 149 A P P E N D I X D Date Notes 1- NOV-01 2- Nov-01 7- Nov-01 8- Nov-OI 9- Nov-01 10- Nov-01 11- Nov-01 12- Nov-01 13- NOV-01 14- NOV-01 15- Nov-01 16- Nov-01 17- Nov-01 18- Nov-01 19- Nov-01 20- Nov-01 2 1 - Nov-01 22- Nov-01 23 - Nov-01 24- Nov-01 25- NOV-01 26- Nov-01 27- Nov-01 28- Nov-01 29- Nov-01 30- Nov-01 1- Dec-01 2- Dec-01 3- Dec-01 4- Dec-01 5- Dec-01 6- Dec-01 7- Dec-01 8- Dec-01 9- Dec-01 10- Dec-01 11- Dec-01 12- Dec-01 13- Dec-01 Oct 12-Dec 13 Average Minimum Max imum St. Dev. Count 150 A P P E N D I X E APPENDIX E: MODEL RESULTS 151 A P P E N D I X E Influent Actual Effluent Predicted Effluent Date Mg NH4 P 0 4 pH Mg NH4 P 0 4 Mg NH4 P 0 4 mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L Reactor A 12-Oct-01 67.9 286.5 40.42 8.2 69.5 239 10.4 42 272 7 13-Oct-01 46.5 263.6 39.96 8.5 41.7 257 10.1 22 250 9 14-Oct-01 52.2 264.1 40.74 8.5 44.8 255 8.3 26 249 8 15-Oct-01 62.5 269.6 43.70 8.4 39.8 263 13.0 34 253 7 16-Oct-01 66.3 277.3 42.21 8.4 38.8 259 8.3 38 261 6 17-Oct-01 47.1 285.6 43.74 8.2 27.1 270 12.4 23 272 13 18-Oct-01 49.5 271.4 46.53 8.5 28.2 306 11.2 21 255 10 24-Oct-01 18.6 285.4 43.80 8.5 14.7 283 17.7 7 278 28 25-Oct-01 61.6 278.6 40.50 8.6 32.3 254 8.9 34 263 5 26-Oct-01 68.1 260.6 33.54 8.6 31.7 230 4.8 45 247 4 27-Oct-01 72.1 266.5 39.02 8.4 36.6 249 7.1 46 251 5 28-Oct-01 74.2 221.7 36.55 8.5 31.4 207 8.5 50 207 5 29-Oct-01 66.3 260.0 35.58 8.4 33.4 251 6.1 43 246 6 30-Oct-01 66.6 260.4 35.46 8.4 35.1 235 6.2 43 247 6 31-Oct-01 59.6 254.2 39.29 8.3 31.5 258 10.8 35 240 8 1-Nov-OI 64.4 250.0 41.11 8.3 32.3 272 9.0 38 235 8 2-Nov-01 65.6 246.9 40.48 8.4 31.5 262 7.8 39 232 7 7-Nov-01 69.9 295.4 42.31 8.1 29.8 262 12.3 43 280 8 8-Nov-01 69.9 261.9 40.07 8.6 25.5 230 6.0 42 246 4 9-Nov-01 66.6 265.2 40.30 8.6 24.9 245 6.2 39 249 5 10-Nov-01 66.5 249.6 42.18 8.6 22.8 244 6.6 37 233 5 11-Nov-01 100.7 248.7 45.73 8.6 33.9 220 5.7 67 229 3 12-Nov-01 78.9 233.4 46.94 8.6 27.7 230 6.4 46 214 5 13-Nov-01 63.5 259.2 50.02 8.4 18.1 256 8.8 31 240 8 14-Nov-01 51.3 277.2 48.33 8.4 17.9 255 9.0 22 260 11 15-Nov-01 53.0 272.0 47.22 8.5 20.2 267 6.4 , 23 255 9 16-Nov-01 55.9 268.6 46.62 8.5 20.2 267 6.4 26 251 8 17-Nov-01 59.3 264.5 45.92 8.5 20.2 267 6.4 29 247 7 18-Nov-01 60.7 246.8 46.92 8.5 23.9 236 6.2 30 229 8 19-Nov-01 79.8 158.5 49.25 8.6 38.3 176 6.1 47 139 7 20-Nov-01 101.9 269.6 45.54 8.5 69.2 275 4.1 69 250 3 21-Nov-01 48.8 330.0 57.87 8.5 13.1 309 11.5 13 310 13 22-Nov-01 49.8 320.5 56.71 8.5 15.1 299 10.2 15 300 12 23-Nov-01 53.0 337.5 56.21 8.5 15.4 317 11.0 17 317 10 24-Nov-01 54.4 320.5 54.16 8.5 17.7 305 8.3 19 300 9 25-Nov-01 54.4 320.5 54.16 8.5 177 305 8.3 19 300 9 26-Nov-01 54.4 320.5 54.16 8.5 17.7 305 8.3 19 300 9 27-Nov-01 56.2 321.4 55.84 8.5 18.4 305 8.3 19 300 9 28-Nov-01 60.0 333.8 55.23 8.5 19.7 312 7.7 22 312 7 29-Nov-01 58.0 309.8 55.25 8.5 17.1 285 8.6 21 289 8 30-Nov-01 57.4 321.1 52.33 8.5 17.5 296 7.4 22 301 8 1-Dec-01 58.6 338.3 58.04 8.4 17.8 305 12.4 20 316 9 2-Dec-01 59.2 356.9 59.81 8.1 22.3 345 17.0 23 336 13 3-Dec-01 53.7 347.7 59.77 8.5 17.9 338 13.7 15 326 11 4-Dec-01 55.5 357.1 56.63 8.3 19.5 351 12.0 20 336 11 5-Dec-01 60.7 364.1 62.85 8.4 18.7 336 12.1 19 340 9 6-Dec-01 62.1 357.2 61.17 8.7 15.1 354 7.8 19 332 6 7-Dec-01 57.1 376.6 67.07 8.4 18.3 330 11.8 14 352 12 8-Dec-01 57.1 376.6 67.07 8.4 18.3 330 11.8 14 352 12 9-Dec-01 57.1 376.6 67.07 8.4 18.3 330 11.8 14 352 12 10-Dec-01 57.1 376.6 67.07 8.4 18.3 330 11.8 14 352 12 11-Dec-01 56.9 361.5 62.88 8.4 17.7 332 11.5 16 338 11 12-Dec-01 62.7 388.8 59.92 8.4 18.2 320 10.5 22 365 8 13-Dec-01 60.4 357.3 57.81 8.4 16.1 346 12.4 22 335 8 Average 152 A P P E N D I X E Influent Predicted Effluent P s i n P S e q P s ou t Date Mg NH4 P 0 4 Mg NH4 P 0 4 mol/L mol/L mol/L mol/L mol/L mol/L Reactor A 12-Oct-01 0.0028 0.020 0.0013 0.00173 0.019 0.00024 7.5E-08 8.0E-09 8.0E-09 13-Oct-01 0.0019 0.019 0.0013 0.00092 0.018 0.00030 4 .6E-08 4.9E-09 4.9E-09 14-Oct-01 0.0021 0.019 0.0013 0.00109 0.018 0.00026 5.3E-08 4.9E-09 4.9E-09 15-Oct-01 0.0026 0.019 0.0014 0.00139 0.018 0.00023 7.0E-08 5.7E-09 5.7E-09 16-Oct-01 0.0027 0.020 0.0014 0.00156 0.019 0.00020 7.4E-08 5.7E-09 5.7E-09 17-Oct-01 0.0019 0.020 0.0014 0.00095 0.019 0.00043 5.6E-08 8.0E-09 8.0E-09 18-Oct-01 0.0020 0.019 0.0015 0.00085 0.018 0.00032 5.9E-08 4.9E-09 4.9E-09 24-Oct-01 0.0008 0.020 0.0014 0.00027 0.020 0.00092 2.2E-08 4.9E-09 4.9E-09 25-Oct-01 0.0025 0.020 0.0013 0.00139 0.019 0.00016 6.6E-08 4.3E-09 4.3E-09 26-Oct-01 0.0028 0.019 0.0011 0.00185 0.018 0.00013 5.6E-08 4.3E-09 4.3E-09 27-Oct-01 0.0030 0.019 0.0013 0.00188 0.018 0.00017 7.1E-08 5.7E-09 5.7E-09 28-OCI-01 0.0031 0.016 0.0012 0.00204 0.015 0.00016 5.7E-08 4.9E-09 4.9E-09 29-Oct-01 0.0027 0.019 0.0011 0.00176 0.018 0.00018 5.8E-08 5.7E-09 5.7E-09 30-Oct-01 0.0027 0.019 0.0011 0.00178 0.018 0.00018 5.8E-08 5.7E-09 5.7E-09 31-Oct-01 0.0025 0.018 0.0013 0.00145 0.017 0.00027 5.6E-08 6.7E-09 6.7E-09 1-Nov-01 0.0027 0.018 0.0013 0.00158 0.017 0.00025 6.3E-08 6.7E-09 6.7E-09 2-Nov-01 0.0027 0.018 0.0013 0.00161 0.017 0.00022 6.2E-08 5.7E-09 5.7E-09 7-Nov-01 0.0029 0.021 0.0014 0.00178 0.020 0.00027 8.3E-08 9.5E-09 9.5E-09 8-Nov-01 0.0029 0.019 0.0013 0.00172 0.018 0.00014 7.0E-08 4.3E-09 4.3E-09 9-Nov-01 0.0027 0.019 0.0013 0.00159 0.018 0.00015 6.7E-08 4.3E-09 4.3E-09 10-Nov-01 0.0027 0.018 0.0014 0.00154 0.017 0.00017 6.6E-08 4 .3E-09 4.3E-09 H-Nov-01 0.0041 0.018 0.0015 0.00276 0.016 0.00009 1.1E-07 4 .3E-09 4.3E-09 12-Nov-01 0.0032 0.017 0.0015 0.00188 0.015 0.00015 8.2E-08 4 .3E-09 4.3E-09 13-Nov-01 0.0026 0.019 0.0016 0.00126 0.017 0.00026 7.8E-08 5.7E-09 5.7E-09 U-Nov-01 0.0021 0.020 0.0016 0.00090 0.019 0.00034 6.5E-08 5.7E-09 5.7E-09 15-Nov-01 0.0022 0.019 0.0015 0.00094 0.018 0.00029 6.5E-08 4 .9E-09 4.9E-09 16-Nov-OI 0.0023 0.019 0.0015 0.00106 0.018 0.00026 6.6E-08 4 .9E-09 4.9E-09 17-Nov-01 0.0024 0.019 0.0015 0.00119 0.018 0.00023 6.8E-08 4.9E-09 4.9E-09 18-Nov-01 0.0025 0.018 0.0015 0.00123 0.016 0.00025 6.7E-08 4.9E-09 4.9E-09 19-Nov-01 0.0033 0.011 0.0016 0.00192 0.010 0.00022 5.9E-08 4.3E-09 4.3E-09 20-Nov-OI 0.0042 0.019 0.0015 0.00282 0.018 0.00010 1.2E-07 4 .9E-09 4.9E-09 21-Nov-01 0.0020 0.024 0.0019 0.00055 0.022 0.00041 8.8E-08 4 .9E-09 4.9E-09 22-Nov-01 0.0020 0.023 0.0018 0.00060 0.021 0.00038 8.6E-08 4 .9E-09 4.9E-09 23-Nov-01 0.0022 0.024 0.0018 0.00069 0.023 0.00032 9.5E-08 4 .9E-09 4.9E-09 24-Nov-OI 0.0022 0.023 0.0017 0.00078 0.021 0.00029 9.0E-08 4 .9E-09 4.9E-09 25 -NOV -01 0.0022 0.023 0.0017 0.00078 0.021 0.00029 9.0E-08 4.9E-09 4.9E-09 26-Nov-01 0.0022 0.023 0.0017 0.00078 0.021 0.00029 9.0E-08 4.9E-09 4.9E-09 27-Nov-01 0.0023 0.023 0.0018 0.00080 0.021 0.00029 9.6E-08 4.9E-09 4.9E-09 28-Nov-OI 0.0025 0.024 0.0018 0.00093 0.022 0.00024 1.0E-07 4 .9E-09 4.9E-09 29-Nov-01 0.0024 0.022 0.0018 0.00087 0.021 0.00027 9.4E-08 4.9E-09 4.9E-09 30-Nov-01 0.0024 0.023 0.0017 0.00092 0.021 0.00025 9.1E-08 4.9E-09 4.9E-09 1-Dec-01 0.0024 0.024 0.0019 0.00084 0.023 0.00030 1.1E-07 5.7E-09 5.7E-09 2-Dec-01 0.0024 0.025 0.0019 . 0.00093 0.024 0.00043 1.2E-07 9.5E-09 9.5E-09 3-Dec-01 0.0022 0.025 0.0019 0.00062 0.023 0.00034 1.1E-07 4.9E-09 4.9E-09 4-Dec-01 0.0023 0.025 0.0018 0.00080 0.024 0.00035 1.1E-07 6.7E-09 6.7E-09 5-Dec-01 0.0025 0.026 0.0020 0.00077 0.024 0.00031 1.3E-07 5.7E-09 5.7E-09 6-Dec-01 0.0026 0.026 0.0020 0.00078 0.024 0.00020 1.3E-07 3.8E-09 3.8E-09 7-Dec-01 0.0024 0.027 0.0022 0.00058 0.025 0.00039 1.4E-07 5.7E-09 5.7E-09 8-Dec-01 0.0024 0.027 0.0022 0.00058 0.025 0.00039 1.4E-07 5.7E-09 5.7E-09 9-Dec-01 0.0024 0.027 0.0022 0.00058 0.025 0.00039 1.4E-07 5.7E-09 5.7E-09 10-Dec-01 0.0024 0.027 0.0022 0.00058 0.025 0.00039 1.4E-07 5.7E-09 5.7E-09 11-Dec-01 0.0023 0.026 0.0020 0.00067 0.024 0.00036 1.2E-07 5.7E-09 5.7E-09 12-Dec-01 0.0026 0.028 0.0019 0.00089 0.026 0.00025 1.4E-07 5.7E-09 5.7E-09 13-Dec-01 0.0025 0.026 0.0019 0.00089 0.024 0.00027 1.2E-07 5.7E-09 5.7E-09 Average 153 Mol Reduct ion Date Reactor A 12-Oct-01 0.0011 13-Oct-01 0.0010 14-Oct-01 0.0011 15-Oct-01 0.0012 16-Oct-01 0.0012 17-Oct-01 0.0010 18-Oct-01 0.0012 24-Oct-01 0.0005 25-Oct-01 0.0011 26-Oct-01 0.0010 27-Oct-01 0.0011 28-Oct-01 0.0010 29-Oct-01 0.0010 30-Oct-01 0.0010 31-Oct-01 0.0010 1-Nov-01 0.0011 2-Nov-01 0.0011 7-Nov-OI 0.0011 8-Nov-OI 0.0012 9-Nov-OI 0.0011 10-Nov-01 0.0012 11-Nov-01 0.0014 12-Nov-OI 0.0014 13-Nov-01 0.0014 14-Nov-01 0.0012 15-Nov-01 0.0012 16-Nov-01 0.0012 17-Nov-01 0.0012 18-Nov-OI 0.0013 19-Nov-01 0.0014 20-Nov-01 0.0014 21-Nov-OI 0.0015 22-Nov-01 0.0014 23-Nov-01 0.0015 24-Nov-01 0.0015 25-Nov-01 0.0015 26-Nov-OI 0.0015 27-NOV-01 0.0015 28-Nov-OI 0.0015 29-Nov-OI 0.0015 30-Nov-01 0.0014 1-Dec-01 0.0016 2-Dec-01 0.0015 3-Dec-01 0.0016 4-Dec-01 0.0015 5-Dec-01 0.0017 6-Dec-01 0.0018 7-Dec-01 0.0018 8-Dec-01 0.0018 9-Dec-01 0.0018 10-Dec-01 0.0018 11-Dec-01 0.0017 12-Dec-01 0.0017 13-Dec-01 0.0016 Average Absolute Concentration error Mg NH4 P 0 4 mg/L mg/L mg/L 27.5 32.5 3.0 19.2 7.3 0.8 18.4 5.7 0.4 6.0 10.0 5.9 0.8 2.0 2.2 3.9 1.8 0.9 7.5 51.2 1.3 8.1 4.5 10.7 1.5 8.6 3.8 13.3 17.2 0.7 9.0 2.3 1.8 18.1 0.4 3.4 9.5 4.5 0.4 8.1 11.9 0.5 3.8 17.8 2.5 6.1 37.0 1.1 7.6 30.4 1.1 13.4 18.0 4.0 16.4 15.7 1.6 13.7 4.1 1.5 14.6 11.1 1.4 33.2 9.3 2.8 18.0 15.8 1.8 12.6 15.7 0.6 3.9 5.2 1.7 2.8 12.3 2.5 5.5 15.9 1.7 8.7 19.9 0.9 6.0 7.0 1.4 8.3 36.6 0.8 0.6 24.6 1.1 0.2 0.6 1.2 0.5 1.2 1.7 1.3 0.4 1.1 1.3 4.8 0.8 1.3 4.8 0.8 1.3 4.8 0.8 1.0 4.8 0.6 2.8 0.2 0.2 4.2 3.7 0.1 4.9 4.9 0.3 2.6 11.3 3.0 0.3 9.2 3.7 2.8 12.5 3.1 0.1 14.7 1.2 0.1 4.0 2.6 3.9 21.6 1.5 4.2 21.8 0.4 4.2 21.8 0.4 4.2 21.8 0.4 4.2 21.8 0.4 1.5 6.0 0.4 3.5 45.2 2.8 5.5 11.1 4.1 7.1 13.1 1.8 % Relative Absolute Error Mg NH4 P 0 4 39.5 13.6 29.2 46.2 2.8 8.1 41.1 2.2 4.8 15.2 3.8 45.7 2.0 0.8 26.6 14.2 0.7 7.3 26.5 16.7 12.1 55.4 1.6 60.7 4.7 3.4 42.9 41.8 7.5 15.4 24.5 0.9 25.7 57.7 0.2 40.5 28.4 1.8 6.3 23.2 5.1 8.7 12.2 6.9 22.7 18.7 13.6 12.7 24.0 11.6 14.5 45.1 6.9 32.7 64.4 6.8 27.0 55.2 1.7 24.4 64.2 4.6 21.6 98.0 4.2 48.6 65.0 6.8 28.0 69.4 6.1 6.9 21.7 2.0 18.4 13.7 4.6 38.8 27.0 5.9 26.0 43.2 7.5 13.6 25.0 3.0 22.5 21.7 20.8 13.9 0.9 9.0 26.2 1.4 0.2 10.4 3.4 0.4 16.3 8.2 0.1 10.4 7.5 1.6 10.2 7.5 1.6 10.2 7.5 1.6 10.2 5.5 1.6 7.4 14.1 0.1 3.3 24.3 1.3 1.5 28.0 1.7 4.1 14.4 3.7 24.1 1.4 2.7 22.1 15.8 3.7 22.7 0.3 4.2 10.2 0.4 1.2 21.9 26.1 6.1 19.4 23.1 6.6 3.4 23.1 6.6 3.4 23.1 6.6 3.4 23.1 6.6 3.4 8.6 1.8 3.6 19.3 14.1 27.1 34.3 3.2 32.8 26.1 4.8 18.8 A P P E N D I X E Actual Error % Relative Actual Error Date Mg mg/L NH4 mg/L P 0 4 mg/L Mg NH4 P 0 4 Reactor A 12-Oct-01 -27.5 32.5 -3.0 -39.5 13.6 -29.2 13-Oct-01 -19.2 -7.3 -0.8 -46.2 -2.8 -8.1 14-Oct-01 -18.4 -5.7 -0.4 -41.1 -2.2 -4.8 15-Oct-01 -6.0 -10.0 -5.9 -15.2 -3.8 -45.7 16-Oct-01 -0.8 2.0 -2.2 -2.0 0.8 -26.6 17-Oct-01 -3.9 1.8 0.9 -14.2 0.7 7.3 18-Oct-01 -7.5 -51.2 -1.3 -26.5 -16.7 -12.1 24-Oct-01 -8.1 -4.5 10.7 -55.4 -1.6 60.7 25-Oct-01 1.5 8.6 -3.8 4.7 3.4 -42.9 26-Oct-01 13.3 17.2 -0.7 41.8 7.5 -15.4 27-Oct-01 9.0 2.3 -1.8 24.5 0.9 -25.7 28-Oct-01 18.1 0.4 -3.4 57.7 0.2 -40.5 29-Oct-01 9.5 -4.5 -0.4 28.4 -1.8 -6.3 30-Oct-01 8.1 11.9 -0.5 23.2 5.1 -8.7 31-Oct-01 3.8 -17.8 -2.5 12.2 -6.9 -22.7 1-Nov-01 6.1 -37.0 -1.1 18.7 -13.6 -12.7 2-Nov-01 7.6 -30.4 -1.1 24.0 -11.6 -14.5 7-Nov-01 13.4 18.0 -4.0 45.1 6.9 -32.7 8-Nov-01 16.4 15.7 -1.6 64.4 6.8 -27.0 9-Nov-01 13.7 4.1 -1.5 55.2 1.7 -24.4 10-Nov-01 14.6 -11.1 -1.4 64.2 -4.6 -21.6 11-Nov-01 33.2 9.3 -2.8 98.0 4.2 -48.6 12-Nov-OI 18.0 -15.8 -1.8 65.0 -6.8 -28.0 13-Nov-01 12.6 -15.7 -0.6 69.4 -6.1 -6.9 14-Nov-01 3.9 5.2 1.7 21.7 2.0 18.4 15-Nov-01 2.8 -12.3 2.5 13.7 -4.6 38.8 16-Nov-01 5.5 -15.9 1.7 27.0 -5.9 26.0 17-Nov-01 8.7 -19.9 0.9 43.2 -7.5 13.6 18-Nov-01 6.0 -7.0 1.4 25.0 -3.0 22.5 19-Nov-01 8.3 -36.6 0.8 21.7 -20.8 13.9 20-Nov-01 -0.6 -24.6 -1.1 -0.9 -9.0 -26.2 21-Nov-01 0.2 0.6 1.2 1.4 0.2 10.4 22-Nov-01 -0.5 1.2 1.7 -3.4 0.4 16.3 23-Nov-01 1.3 -0.4 -1.1 8.2 -0.1 -10.4 24-Nov-01 1.3 -4.8 0.8 7.5 -1.6 10.2 25-Nov-OI 1.3 -4.8 0.8 7.5 -1.6 10.2 26-Nov-01 1.3 -4.8 0.8 7.5 -1.6 10.2 27-Nov-01 1.0 -4.8 0.6 5.5 -1.6 7.4 28-Nov-OI 2.8 0.2 -0.2 14.1 0.1 -3.3 29-Nov-01 4.2 3.7 -0.1 24.3 1.3 -1.5 30-Nov-OI 4.9 4.9 0.3 28.0 1.7 4.1 1-Dec-01 2.6 11.3 -3.0 14.4 3.7 -24.1 2-Dec-01 0.3 -9.2 -3.7 1.4 -2.7 -22.1 3-Dec-01 -2.8 -12.5 -3.1 -15.8 -3.7 -22.7 4-Dec-01 0.1 -14.7 -1.2 0.3 -4.2 -10.2 5-Dec-01 0.1 4.0 -2.6 0.4 1.2 -21.9 6-Dec-01 3.9 -21.6 -1.5 26.1 -6.1 -19.4 7-Dec-01 -4.2 21.8 0.4 -23.1 6.6 3.4 8-Dec-01 -4.2 21.8 0.4 -23.1 6.6 3.4 9-Dec-01 -4.2 21.8 0.4 -23.1 6.6 3.4 10-Dec-01 -4.2 21.8 0.4 -23.1 6.6 3.4 11-Dec-01 -1.5 6.0 -0.4 -8.6 1.8 -3.6 12-Dec-01 3.5 45.2 -2.8 19.3 14.1 -27.1 13-Dec-01 5.5 -11.1 -4.1 34.3 -3.2 -32.8 Average 2.9 -2.3 -0.7 12.7 -0.9 -8.3 155 A P P E N D I X E Influent Actual Effluent Predicted Effluent Date Mg N H 4 P 0 4 pH Mg NH4 P 0 4 Mg NH4 P 0 4 mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L Reactor B 12-Oct-01 83.9 279.4 39.41 8.4 63.8 240 12.6 56 263 4 13-Oct-01 53.4 260.4 39.47 8.4 49.4 242 10.7 29 246 8 14-Oct-01 50.4 265.0 40.88 8.4 45.0 246 9.4 26 251 9 15-Oct-01 60.6 270.9 43.92 8.4 34.3 274 13.0 32 254 7 16-Oct-01 63.3 279.1 42.48 8.4 37.4 261 11.0 35 263 7 17-Oct-01 62.9 275.4 42.19 8.5 42.1 270 8.8 34 259 6 18-Oct-01 51.0 270.9 46.46 8.5 30.9 258 12.1 22 254 9 24-Oct-01 18.6 285.5 43.81 8.4 17.3 280 18.2 7 279 29 25-Oct-01 63.2 277.8 40.39 8.4 38.6 241 7.8 36 262 6 26-Oct-01 69.8 259.8 33.44 8.4 43.4 250 5.8 48 247 5 27-Oct-01 74.5 265.3 38.85 8.4 44.2 265 6.4 48 250 5 28-Oct-01 76.7 220.6 36.38 8.4 35.1 237 8.4 53 207 6 29-Oct-01 69.7 257.9 35.29 8.4 47.9 233 6.5 46 244 5 30-Oct-01 70.0 258.8 35.24 8.4 48.0 227 6.3 46 245 5 31-Oct-01 60.9 255.2 39.45 8.3 43.0 251 11.4 36 241 8 1-Nov-01 66.1 249.5 41.02 8.4 46.0 240 8.2 39 234 7 2-Nov-01 64.5 247.9 40.64 8.3 47.0 231 8.9 39 233 8 7-Nov-01 70.8 295.3 42.29 8 34.7 239 14.0 45 281 10 8-Nov-01 69.9 268.3 41.05 8 31.1 238 13.9 46 254 10 9-Nov-01 67.4 271.0 41.18 8 30.8 242 14.1 44 257 11 10-Nov-01 68.3 251.5 42.51 8 30.5 232 15.7 44 238 12 H-Nov-01 63.3 277.0 50.94 8 22.9 252 16.2 34 260 14 12-Nov-01 63.7 247.3 49.73 8 22.6 220 14.2 36 231 15 13-Nov-01 65.7 260.8 50.32 8 27.4 257 16.9 37 244 13 H-Nov-01 58.0 274.9 47.93 7.7 37.9 282 27.0 38 263 22 15-Nov-01 54.9 273.6 47.49 7.8 37.8 270 23.5 34 261 21 16-Nov-01 55.3 273.2 47.42 7.8 37.8 270 23.5 34 261 20 17-Nov-01 55.6 272.8 47.35 7.8 37.8 270 23.5 34 261 20 18-Nov-01 56.1 252.5 47.99 7.7 37.4 255 24.8 38 242 25 19-Nov-01 29.2 189.5 58.88 7.8 18.0 194 43.6 21 185 48 20-Nov-01 55.0 326.7 55.19 7.8 29.8 313 29.4 28 311 21 21-Nov-01 51.7 332.1 58.23 7.8 29.3 330 33.2 24 316 23 22-Nov-01 51.6 324.4 57.40 7.8 28.9 320 29.8 25 309 23 23-Nov-OI 53.1 341.4 56.85 7.8 32.6 321 31.3 26 326 22 24-Nov-OI 56.7 324.0 54.74 7.7 35.4 321 28.0 32 310 23 25-Nov-01 56.7 324.0 54.74 7.7 35.4 321 28.0 32 310 23 26-Nov-01 56.7 324.0 54.74 7.7 35.4 321 28.0 32 310 23 27-Nov-OI 57.1 324.8 56.42 7.7 36.3 317 26.4 31 310 23 28-Nov-01 60.2 336.4 55.66 7.7 36.2 334 27.2 33 321 21 29-Nov-OI 62.9 313.2 55.86 7.8 33.5 311 25.6 33 296 18 30-Nov-01 59.3 326.7 53.24 7.8 32.2 326 24.2 32 311 18 1-Dec-01 59.2 345.3 59.24 7.7 36.6 335 34.1 30 329 23 2-Dec-01 56.9 369.1 61.86 7.6 36.1 360 35.1 30 353 27 3-Dec-01 58.3 350.7 60.28 7.6 34.1 339 32.6 32 335 26 4-Dec-01 55.3 377.7 59.90 7.7 32.7 359 26.3 27 361 23 5-Dec-01 61.7 367.8 63.49 7.6 35.2 378 34.2 32 351 25 6-Dec-01 57.6 366.2 62.71 7.7 33.9 358 34.1 27 349 24 7-Dec-01 60.4 374.7 66.73 7.6 33.6 351 30.4 29 357 27 8-Dec-01 60.4 374.7 66.73 7.6 33.6 351 30.4 29 357 27 9-Dec-01 60.4 374.7 66.73 7.6 33.6 351 30.4 29 357 27 10-Dec-01 60.4 374.7 66.73 7.6 33.6 351 30.4 29 357 27 11-Dec-01 59.2 368.9 64.18 7.6 32.2 395 30.3 30 352 27 12-Dec-01 66.8 390.2 60.13 7.6 31.8 442 28.9 36 372 21 13-Dec-01 65.0 359.9 58.23 7.6 32.6 362 33.3 37 344 22 Average 156 A P P E N D I X E Influent Predicted Effluent P s i n P s e q P s ou t Date Mg NH4 P 0 4 Mg NH4 P 0 4 mol/L mol/L mol/L mol/L mol/L mol/L Reactor B 12-Oct-01 0.0035 0.020 0.0013 0.00231 0.019 0.00013 8.8E-08 5.7E-09 5.7E-09 13-Oct-01 0.0022 0.019 0.0013 0.00119 0.018 0.00027 5.2E-08 5.7E-09 5.7E-09 14-Oct-01 0.0021 0.019 0.0013 0.00106 0.018 0.00030 5.2E-08 5.7E-09 5.7E-09 15-Oct-01 0.0025 0.019 0.0014 0.00132 0.018 0.00024 6.8E-08 5.7E-09 5.7E-09 16-Oct-01 0.0026 0.020 0.0014 0.00145 0.019 0.00021 7.1E-08 5.7E-09 5.7E-09 17-Oct-01 0.0026 0.020 0.0014 0.00141 0.018 0.00019 6.9E-08 4 .9E-09 4.9E-09 18-Oct-01 0.0021 0.019 0.0015 0.00090 0.018 0.00030 6.1E-08 4 .9E-09 4.9E-09 24-Oct-01 0.0008 0.020 0.0014 0.00030 0.020 0.00095 2.2E-08 5.7E-09 5.7E-09 25-Oct-01 0.0026 0.020 0.0013 0.00150 0.019 0.00020 6.7E-08 5.7E-09 5.7E-09 26-Oct-01 0.0029 0.019 0.0011 0.00196 0.018 0.00017 5.8E-08 5.7E-09 5.7E-09 27-Oct-01 0.0031 0.019 0.0013 0.00197 0.018 0.00016 7.3E-08 5.7E-09 5.7E-09 28-Oct-01 0.0032 0.016 0.0012 0.00216 0.015 0.00018 5.8E-08 5.7E-09 5.7E-09 29-Oct-01 0.0029 0.018 0.0011 0.00190 0.017 0.00017 6.0E-08 5.7E-09 5.7E-09 30-Oct-01 0.0029 0.018 0.0011 0.00191 0.018 0.00017 6.1E-08 5.7E-09 5.7E-09 31-Oct-01 0.0025 0.018 0.0013 0.00149 0.017 0.00026 5.8E-08 6.7E-09 6.7E-09 1-Nov-01 0.0027 0.018 0.0013 0.00161 0.017 0.00021 6.4E-08 5.7E-09 5.7E-09 2-Nov-01 0.0027 0.018 0.0013 0.00159 0.017 0.00025 6.2E-08 6.7E-09 6.7E-09 7-Nov-01 0.0029 0.021 0.0014 0.00186 0.020 0.00031 8.4E-08 1.1E-08 1.1E-08 8-Nov-01 0.0029 0.019 0.0013 0.00189 0.018 0.00034 7.3E-08 1.1E-08 1.1E-08 9-Nov-01 0.0028 0.019 0.0013 0.00179 0.018 0.00035 7.1E-08 1.1E-08 1.1E-08 10-Nov-01 0.0028 0.018 0.0014 0.00181 0.017 0.00037 6.9E-08 1.1E-08 1.1E-08 11-Nov-01 0.0026 0.020 0.0016 0.00140 0.019 0.00044 8.5E-08 1.1E-08 1.1E-08 12-Nov-01 0.0026 0.018 0.0016 0.00148 0.017 0.00047 7.4E-08 1.1E-08 1.1E-08 13-Nov-01 0.0027 0.019 0.0016 0.00151 0.017 0.00044 8.2E-08 1.1E-08 1.1E-08 14-Nov-01 0.0024 0.020 0.0015 0.00156 0.019 0.00073 7.2E-08 2.1E-08 2.1E-08 15-Nov-OI 0.0023 0.020 0.0015 0.00139 0.019 0.00066 6.8E-08 1.7E-08 1.7E-08 16-Nov-01 0.0023 0.020 0.0015 0.00140 0.019 0.00066 6.8E-08 1.7E-08 1.7E-08 17-Nov-01 0.0023 0.019 0.0015 0.00141 0.019 0.00065 6.8E-08 1.7E-08 1.7E-08 18-Nov-01 0.0023 0.018 0.0015 0.00155 0.017 0.00079 6.5E-08 2.1E-08 2.1E-08 19-Nov-01 0.0012 0.014 0.0019 0.00084 0.013 0.00155 3.1E-08 1.7E-08 1.7E-08 20-Nov-01 0.0023 0.023 0.0018 0.00115 0.022 0.00067 9.4E-08 1.7E-08 1.7E-08 21-Nov-01 0.0021 0.024 0.0019 0.00100 0.023 0.00076 9.5E-08 1.7E-08 1.7E-08 22-Nov-OI 0.0021 0.023 0.0019 0.00103 0.022 0.00076 9.1E-08 1.7E-08 1.7E-08 23-NOV-01 0.0022 0.024 0.0018 0.00105 0.023 0.00070 9.8E-08 1.7E-08 1.7E-08 24-Nov-OI 0.0023 0.023 0.0018 0.00130 0.022 0.00074 9.5E-08 2.1E-08 2.1E-08 25-Nov-01 0.0023 0.023 0.0018 0.00130 0.022 0.00074 9.5E-08 2.1E-08 2.1E-08 26-Nov-01 0.0023 0.023 0.0018 0.00130 0.022 0.00074 9.5E-08 2.1E-08 2.1E-08 27-NOV-01 0.0023 0.023 0.0018 0.00128 0.022 0.00075 9.9E-08 2.1E-08 2.1E-08 28-NOV-01 0.0025 0.024 0.0018 0.00136 0.023 0.00068 1.1E-07 2.1E-08 2.1E-08 29-NOV-01 0.0026 0.022 0.0018 0.00138 0.021 0.00059 1.0E-07 1.7E-08 1.7E-08 30-Nov-OI 0.0024 0.023 0.0017 0.00131 0.022 0.00059 9.8E-08 1.7E-08 1.7E-08 1-Dec-01 0.0024 0.025 0.0019 0.00125 0.023 0.00073 1.1E-07 2.1E-08 2.1E-08 2-Dec-01 0.0023 0.026 0.0020 0.00121 0.025 0.00087 1.2E-07 2.7E-08 2.7E-08 3-Dec-01 0.0024 0.025 0.0019 0.00131 0.024 0.00085 1.2E-07 2.7E-08 2.7E-08 4-Dec-01 0.0023 0.027 0.0019 0.00110 0.026 0.00076 1.2E-07 2.1E-08 2.1E-08 5-Dec-01 0.0025 0.026 0.0020 0.00131 0.025 0.00082 1.4E-07 2.7E-08 2.7E-08 6-Dec-01 0.0024 0.026 0.0020 0.00112 0.025 0.00077 1.3E-07 2.1E-08 2.1E-08 7-Dec-01 0.0025 0.027 0.0022 0.00120 0.025 0.00087 1.4E-07 2.7E-08 2.7E-08 8-Dec-01 0.0025 0.027 0.0022 0.00120 0.025 0.00087 1.4E-07 2.7E-08 2.7E-08 9-Dec-01 0.0025 0.027 0.0022 0.00120 0.025 0.00087 1.4E-07 2.7E-08 2.7E-08 10-Dec-01 0.0025 0.027 0.0022 0.00120 0.025 0.00087 1.4E-07 2.7E-08 2.7E-08 11-Dec-01 0.0024 0.026 0.0021 0.00123 0.025 0.00087 1.3E-07 2.7E-08 2.7E-08 12-Dec-01 0.0027 0.028 0.0019 0.00149 0.027 0.00068 1.5E-07 2.7E-08 2.7E-08 13-Dec-01 0.0027 0.026 0.0019 0.00151 0.025 0.00072 1.3E-07 2.7E-08 2.7E-08 Average 157 A P P E N D I X E Mol Reduct ion Date Reactor B 12-Oct-01 0.0011 13-Oct-01 0.0010 14-Oct-01 0.0010 15-Oct-01 0.0012 16-Oct-01 0.0012 17-Oct-01 0.0012 18-Oct-01 0.0012 24-Oct-01 0.0005 25-Oct-01 0.0011 26-Oct-01 0.0009 27-Oct-01 0.0011 28-Oct-01 0.0010 29-Oct-01 0.0010 30-Oct-01 0.0010 31-Oct-01 0.0010 1-Nov-01 0.0011 2-Nov-01 0.0011 7-Nov-01 0.0011 8-Nov-01 0.0010 9-Nov-01 0.0010 10-Nov-01 0.0010 11-NOV-01 0.0012 12-Nov-01 0.0011 13-Nov-01 0.0012 14-Nov-OI 0.0008 15-Nov-01 0.0009 16-Nov-01 0.0009 17-Nov-01 0.0009 18-Nov-01 0.0008 19-Nov-01 0.0004 20-Nov-01 0.0011 21-Nov-01 0.0011 22-Nov-01 0.0011 23-Nov-OI 0.0011 24-Nov-OI 0.0010 25-Nov-OI 0.0010 26-Nov-01 0.0010 27-Nov-01 0.0011 28-Nov-OI 0.0011 29-Nov-01 0.0012 30-Nov-01 0.0011 1-Dec-01 0.0012 2-Dec-01 0.0011 3-Dec-01 0.0011 4-Dec-01 0.0012 5-Dec-01 0.0012 6-Dec-01 0.0013 7-Dec-01 0.0013 8-Dec-01 0.0013 9-Dec-01 0.0013 10-Dec-01 0.0013 11-Dec-01 0.0012 12-Dec-01 0.0013 13-Dec-01 0.0012 Average Absolute Concentration error Mg NH4 P 0 4 mg/L mg/L mg/L 7.6 23.4 8.5 20.3 4.3 2.3 19.3 4.8 0.0 2.3 19.6 5.6 2.3 1.9 4.5 7.8 11.0 3.0 9.0 3.9 2.8 10.0 1.0 11.3 2.1 21.4 1.5 4.2 3.0 0.7 3.8 15.0 1.4 17.4 30.3 2.8 1.7 11.3 1.2 1.5 18.3 1.0 6.7 10.0 3.3 6.9 6.1 1.6 8.2 2.0 1.1 10.4 41.5 4.4 14.7 16.4 3.5 12.8 15.2 3.3 13.5 5.6 4.1 11.2 8.1 2.5 13.5 11.3 0.3 9.4 12.9 3.4 0.1 18.6 4.5 4.0 8.6 3.0 3.7 9.0 3.1 3.4 9.5 3.3 0.4 13.1 0.2 2.5 9.4 4.3 1.8 1.9 8.6 4.9 13.6 9.7 3.9 11.0 6.3 7.0 4.5 9.5 3.7 11.4 5.0 3.7 11.4 5.0 3.7 11.4 5.0 5.2 7.2 3.0 3.1 13.2 6.0 0.1 14.8 7.3 0.3 15.1 5.9 6.2 6.3 11.6 6.6 6.7 8.1 2.4 3.6 6.1 6.1 2.2 2.9 3.5 27.5 8.9 6.8 9.4 10.2 4.4 5.8 3.4 4.4 5.8 3.4 4.4 5.8 3.4 4.4 5.8 3.4 2.3 43.0 3.5 4.3 69.5 7.9 4.2 18.3 11.0 6.1 12.8 4.6 % Relative Absolute Error Mg N H 4 P 0 4 11.9 9.7 67.6 41.2 1.8 21.1 42.9 1.9 0.4 6.6 7.1 42.9 6.1 0.7 40.6 18.4 4.1 33.6 29.0 1.5 22.9 57.5 0.4 61.9 5.5 8.9 19.2 9.7 1.2 11.4 8.6 5.7 21.4 49.6 12.8 33.8 3.5 4.9 17.7 3.1 8.0 16.0 15.7 4.0 28.9 15.0 2.5 19.5 17.5 0.9 11.9 30.0 17.4 31.7 47.4 6.9 25.3 41.4 6.3 23.4 44.4 2.4 26.3 48.8 3.2 15.7 59.6 5.2 2.1 34.2 5.0 20.2 0.3 6.6 16.8 10.7 3.2 12.6 9.9 3.3 13.2 9.1 3.5 13.9 1.1 5.1 0.8 14.0 4.9 9.8 5.9 0.6 29.3 16.7 4.1 29.3 13.6 3.4 21.2 21.6 1.4 30.3 10.4 3.6 18.0 10.4 3.6 18.0 10.4 3.6 18.0 14.3 2.3 11.4 8.5 3.9 22.1 0.2 4.7 28.4 1.0 4.6 24.3 17.0 1.9 34.0 18.2 1.9 23.0 6.9 1.1 18.8 18.6 0.6 10.9 10.0 7.3 25.9 20.0 2.6 30.1 13.0 1.6 11.1 13.0 1.6 11.1 13.0 1.6 11.1 13.0 1.6 11.1 7.3 10.9 11.5 13.5 15.7 27.5 12.8 5.1 33.0 18.2 4.4 22.1 158 A P P E N D I X E Actual Error % Relative Actual Error Date Mg mg/L NH4 mg/L P 0 4 mg/L Mg NH4 P 0 4 Reactor B 12-Oct-01 -7.6 23.4 -8.5 -11.9 9.7 -67.6 13-Oct-01 -20.3 4.3 -2.3 -41.2 1.8 -21.1 14-Oct-01 -19.3 4.8 0.0 -42.9 1.9 -0.4 15-Oct-01 -2.3 -19.6 -5.6 -6.6 -7.1 -42.9 16-Oct-01 -2.3 1.9 -4.5 -6.1 0.7 -40.6 17-Oct-01 -7.8 -11.0 -3.0 -18.4 -4.1 -33.6 18-Oct-01 -9.0 -3.9 -2.8 -29.0 -1.5 -22.9 24-Oct-01 -10.0 -1.0 11.3 -57.5 -0.4 61.9 25-Oct-01 -2.1 21.4 -1.5 -5.5 8.9 -19.2 26-Oct-01 4.2 -3.0 -0.7 9.7 -1.2 -11.4 27-Oct-01 3.8 -15.0 -1.4 8.6 -5.7 -21.4 28-Oct-01 17.4 -30.3 -2.8 49.6 -12.8 -33.8 29-Oct-01 -1.7 11.3 -1.2 -3.5 4.9 -17.7 30-Oct-01 -1.5 18.3 -1.0 -3.1 8.0 -16.0 31-Oct-01 -6.7 -10.0 -3.3 -15.7 -4.0 -28.9 1-Nov-01 -6.9 -6.1 -1.6 -15.0 -2.5 -19.5 2-Nov-01 -8.2 2.0 -1.1 -17.5 0.9 -11.9 7-Nov-01 10.4 41.5 -4.4 30.0 17.4 -31.7 8-Nov-01 14.7 16.4 -3.5 47.4 6.9 -25.3 9-Nov-01 12.8 15.2 -3.3 41.4 6.3 -23.4 10-Nov-01 13.5 5.6 -4.1 44.4 2.4 -26.3 11-Nov-01 11.2 8.1 -2.5 48.8 3.2 -15.7 12-Nov-01 13.5 11.3 0.3 59.6 5.2 2.1 13-Nov-01 9.4 -12.9 -3.4 34.2 -5.0 -20.2 14-Nov-01 0.1 -18.6 -4.5 0.3 -6.6 -16.8 15-Nov-01 -4.0 -8.6 -3.0 -10.7 -3.2 -12.6 16-Nov-01 -3.7 -9.0 -3.1 -9.9 -3.3 -13.2 17-Nov-OI -3.4 -9.5 -3.3 -9.1 -3.5 -13.9 18-Nov-01 0.4 -13.1 -0.2 1.1 -5.1 -0.8 19-Nov-01 2.5 -9.4 4.3 14.0 -4.9 9.8 20-Nov-01 -1.8 -1.9 -8.6 -5.9 -0.6 -29.3 21-Nov-01 -4.9 -13.6 -9.7 -16.7 -4.1 -29.3 22-Nov-01 -3.9 -11.0 -6.3 -13.6 -3.4 -21.2 23-Nov-01 -7.0 4.5 -9.5 -21.6 1.4 -30.3 24-Nov-OI -3.7 -11.4 -5.0 -10.4 -3.6 -18.0 25-Nov-01 -3.7 -11.4 -5.0 -10.4 -3.6 -18.0 26-Nov-OI -3.7 -11.4 -5.0 -10.4 -3.6 -18.0 27-Nov-OI -5.2 -7.2 -3.0 -14.3 -2.3 -11.4 28-Nov-OI -3.1 -13.2 -6.0 -8.5 -3.9 -22.1 29-Nov-OI -0.1 -14.8 -7.3 -0.2 -4.7 -28.4 30-Nov-OI -0.3 -15.1 -5.9 -1.0 -4.6 -24.3 1-Dec-01 -6.2 -6.3 -11.6 -17.0 -1.9 -34.0 2-Dec-01 -6.6 -6.7 -8.1 -18.2 -1.9 -23.0 3-Dec-01 -2.4 -3.6 -6.1 -6.9 -1.1 -18.8 4-Dec-01 -6.1 2.2 -2.9 -18.6 0.6 -10.9 5-Dec-01 -3.5 -27.5 -8.9 -10.0 -7.3 -25.9 6-Dec-01 -6.8 -9.4 -10.2 -20.0 -2.6 -30.1 7-Dec-01 -4.4 5.8 -3.4 -13.0 1.6 -11.1 8-Dec-01 -4.4 5.8 -3.4 -13.0 1.6 -11.1 9-Dec-01 -4.4 5.8 -3.4 -13.0 1.6 -11.1 10-Dec-01 -4.4 5.8 -3.4 -13.0 1.6 -11.1 11-Dec-01 -2.3 -43.0 -3.5 -7.3 -10.9 -11.5 12-Dec-01 4.3 -69.5 -7.9 13.5 -15.7 -27.5 13-Dec-01 4.2 -18.3 -11.0 12.8 -5.1 -33.0 Average -1.5 -4.8 -4.0 -2.8 -1.2 -19.3 159 APPENDIX F APPENDIX F: CRYSTAL CHEMICAL ANALYSIS 160 A P P E N D I X F Crys ta l So lu t ion Date Reac to r M a s s V o l u m e M g C a K A l F e N H 3 - N P 0 4 - P S a m p l e m g L mg /L mg /L mg /L m g / L m g / L m g / L mg /L 13-Nov-OI A >2mm 31.0 0 .050 60.1 5.3 0.2 0.3 0.2 33 .5 77.8 13-NOV-01 A > 1 m m 32.1 0.050 60.0 5.9 0.3 0.1 0.1 34.0 77.6 13-Nov-01 A > 0 . 5 m m 30.4 0.050 58.9 4.6 0.3 1.1 0.3 32.8 75 .5 13-Nov-01 A < 0 . 5 m m 30.4 0.050 60.6 2.5 0.2 0.4 0.1 31 .9 76.1 30-Nov-01 A >2mm 30 .3 0 .050 61.8 7.3 0.3 0.2 0.2 33.4 79.4 30-Nov-01 A > 1 m m 30.1 0.050 60 .5 2.6 0.2 0.4 0.1 32 .9 76.7 30-Nov-01 A > 0 . 5 m m 30.6 0 .050 61 .3 3.4 0.2 -0 .3 0.1 34.0 79 .3 30-Nov-01 A < 0 . 5 m m 29.5 0 .050 62.6 1.7 0.3 0.2 0.1 30 .0 84 .0 12-Dec-01 A >2mm 28.6 0 .050 57.8 3.7 0.2 -0.1 0.1 32.8 73 .5 12-Dec-01 A > 1 m m 30.8 0 .050 63.1 3.6 0.2 0.0 0.2 34.7 80.4 12-Dec-01 A > 0 . 5 m m 29.6 0.050 59.4 1.4 0.2 -0.4 0.1 33 .3 74.4 12-Dec-01 A < 0 . 5 m m 31 .3 0 .050 65.7 1.4 0.2 -1.1 0.1 36.0 80.6 20-Nov-01 B > 2 m m 30 .3 0 .050 55.4 1.6 0.2 -0 .5 0.1 32.8 69 .9 20-Nov-01 B > 1 m m 29.4 0 .050 60 .3 1.4 0.2 -0.1 0.1 33.7 76.1 20-Nov-01 B>0 .5mm 29 .3 0 .050 58.5 4 .5 0.2 -0 .5 0.1 33.8 77 .0 20-Nov-01 B<0 .5mm 31.0 0 .050 61.8 1.5 0.2 -0 .5 0.2 36.1 79.6 2 -Dec-01 B > 2 m m 30.7 0 .050 60.7 1.1 0.2 -0.4 0.2 36 .0 78.1 2 -Dec-01 B > 1 m m 29.8 0 .050 58.7 1.0 0.2 -0.8 0.2 34.6 76.3 2 -Dec-01 B>0 .5mm 29.9 0 .050 61.4 5.9 0.2 -0.4 0.4 34 .9 80 .3 2 -Dec-01 B<0 .5mm 29.8 0 .050 64 .3 3.9 0.2 0.0 0.3 33 .0 83 .3 11-Dec-01 B > 2 m m 30.9 0.050 61.0 1.3 0.2 0.0 0.2 36 .0 78.4 11-Dec-01 B > 1 m m 29.7 0 .050 57.6 1.2 0.2 0.1 0.3 35.1 78.2 11-Dec-01 B>0 .5mm 30.7 0 .050 61 .5 7.8 0.3 0.9 0.4 35 .3 83.7 11-Dec-01 B<0 .5mm 30.4 0 .050 53.6 1.3 0.2 0.3 0.2 25 .5 70.7 30-Nov-01 A > 1 m m 29.4 0 .050 56.6 2 .5 0.2 0.1 0.1 34 .3 75.3 2 -Dec-01 B>0 .5mm 30.8 0 .050 59.1 1.1 0.2 -0.2 0.9 35 .3 78.9 11-Dec-01 B > 2 m m 31.0 0 .050 60.1 1.5 0.2 -0 .3 0.3 36 .2 79.4 13-Nov-01 A O . 5 m m 30.8 0 .050 58.6 3.6 0.3 0.3 0.2 34 .0 79.7 11-Dec-01 B Bulk 29 .2 0 .050 57 .5 1.2 0.2 -0 .3 0.2 32.4 75.0 A v e r a g e 30 .3 0.050 60.0 3.0 0.2 -0.1 0.2 33.7 77.8 min 28.6 0 .050 53.6 1.0 0.2 -1.1 0.1 25 .5 69 .9 m a x 32.1 0.050 65.7 7.8 0.3 1.1 0.9 36 .2 84 .0 S t .Dev . 0.8 0 .000 2.5 2.0 0.0 0.5 0.2 2.1 3.3 161 A P P E N D I X F Theore t ica l Theore t ica l Theore t ica l Da te R e a c t o r M g N H 3 - N P 0 4 - P % Struvi te S a m p l e mg /L mg /L mg /L 13-Nov-01 A >2mm 61.4 35.4 78 .3 97 .3 13-Nov-01 A > 1 m m 63.6 36.6 81.1 94 .3 13-Nov-01 A > 0 . 5 m m 60.2 34.7 76.8 96 .9 13-Nov-01 A < 0 . 5 m m 60.2 34.7 76.8 97 .2 30-Nov-01 A >2mm 60.0 34.6 76 .5 101.1 3 0 - N o v - O i A > 1 m m 59.6 34.4 76.0 99 .3 30-Nov-01 A > 0 . 5 m m 60.6 34 .9 77.3 100.4 30-Nov-01 A < 0 . 5 m m 58.5 33.7 74 .5 102.9 12-Dec-01 A >2mm 56.7 32.6 72.2 101.4 12-Dec-01 A > 1 m m 61.0 35.2 77.8 101.8 12-Dec-01 A > 0 . 5 m m 58.7 33.8 74.8 99 .8 12-Dec-01 A < 0 . 5 m m 62.0 35.7 79.0 102.9 20-Nov-01 B > 2 m m 60.0 34.6 76 .5 92.8 20-Nov-01 B > 1 m m 58.3 33.6 74.2 102.2 20-Nov-01 B>0 .5mm 58.1 33.4 74.0 101.9 20-Nov-01 B<0 .5mm 61.4 35.4 78 .3 101.4 2 -Dec-01 B > 2 m m 60.8 35.0 77 .5 101.1 2 -Dec-01 B > 1 m m 59.0 34.0 75 .3 100.9 2 -Dec-01 B>0 .5mm 59.2 34.1 75 .5 104.1 2 -Dec-01 B<0 .5mm 59.0 34.0 75.3 105 .5 11-Dec-01 B > 2 m m 61.2 35.3 78 .0 100.8 11-Dec-01 B > 1 m m 58.9 33.9 75 .0 101.9 11-Dec-01 B>0 .5mm 60 .8 35.0 77 .5 103.3 11-Dec-01 B<0 .5mm 60.2 34.7 76.8 84 .9 30-Nov-01 A > 1 m m 58 .3 33.6 74.2 100.3 2 -Dec-01 B>0 .5mm 61.0 35.2 77.8 99.6 11-Dec-01 B > 2 m m 61.4 35.4 78 .3 100.5 13-Nov-01 A < 0 . 5 m m 61.0 35.2 77.8 98.4 11-Dec-01 B Bulk 57 .9 33 .3 73.7 99.4 A v e r a g e 60.0 34.6 76.4 99.8 min 56.7 32.6 72 .2 84 .9 m a x 63.6 36.6 81.1 105.5 S t .Dev . 1.5 0.9 1.9 4 .0 162 A P P E N D I X F % o f %0f % o f Date R e a c t o r Theore t ica l Theore t ica l Theore t i ca l S a m p l e M g N H 3 - N P 0 4 - P 13-Nov-01 A > 2 m m 97.8 94.8 99.4 13-Nov-01 A > 1 m m 94.4 92.8 95.7 13-Nov-01 A > 0 . 5 m m 97.8 94.4 98.4 13-Nov-01 A < 0 . 5 m m 100.5 91 .9 99.1 30-Nov-01 A >2mm 103.0 96.7 103.7 30-Nov-01 A > 1 m m 101.5 95.6 101.0 30-Nov-01 A > 0 . 5 m m 101.1 97.4 102.6 30-Nov-OI A < 0 . 5 m m 107.1 89.1 112.7 12-Dec-01 A >2mm 101.9 100.6 101.7 12-Dec-01 A > 1 m m 103.4 98.7 103.3 12-Dec-01 A > 0 . 5 m m 101.3 98.7 99 .5 12-Dec-01 A < 0 . 5 m m 105.9 100.7 101.9 20-Nov-01 B > 2 m m 92.3 94 .8 91 .3 20-Nov-01 B > 1 m m 103.6 100.5 102.5 20-Nov-01 B>0 .5mm 100.7 101.0 104.0 20-Nov-01 B<0 .5mm 100.7 101.9 101.7 2 -Dec-01 B > 2 m m 99.8 102.6 100.7 2 -Dec-01 B > 1 m m 99.4 101.8 101.4 2 -Dec-01 B>0 .5mm 103.6 102.3 106.3 2 -Dec-01 B<0 .5mm 109.0 97.0 110.6 11-Dec-01 B > 2 m m 99.7 102.1 100.5 11-Dec-01 B > 1 m m 97.9 103.4 104.3 11-Dec-01 B>0 .5mm 101.2 100.7 108.0 11-Dec-01 B<0 .5mm 89.0 73.6 92.1 30-Nov-01 A > 1 m m 97.2 102.1 101.4 2 -Dec-01 B>0 .5mm 96 .9 100.4 101.4 11-Dec-01 B > 2 m m 97.8 102.2 101.4 13-Nov-01 A < 0 . 5 m m 96.0 96.6 102.4 11-Dec-01 B Bulk 99 .3 97 .2 101.7 A v e r a g e 100.0 97.6 101.8 min 89.0 73.6 91 .3 m a x 109.0 103.4 112.7 S t .Dev . 4.2 5.9 4.4 163 A P P E N D I X F Date Reac to r M g C a K A l F e N H 3 - N P 0 4 - P S a m p l e m M o l / L m M o l / L m M o l / L m M o l / L m M o l / L m M o l / L m M o l / L 13-Nov-01 A >2mm 2.47 0.13 0 .005 0.009 0 .003 2.40 2.51 13-Nov-01 A > 1 m m 2.47 0.15 0.007 0 .003 0.002 2 .43 2 .50 13-Nov-01 A > 0 . 5 m m 2.42 0.11 0.007 0.042 0 .005 2.34 2.44 13-Nov-01 A < 0 . 5 m m 2.49 0.06 0.006 0.016 0.002 2 .28 2 .45 30-Nov-01 A >2mm 2.54 0.18 0.006 0.006 0.004 2 .39 2.56 30-Nov-01 A > 1 m m 2.49 0.06 0.006 0.014 0.001 2 .35 2.48 30-Nov-01 A > 0 . 5 m m 2.52 0.08 0 .005 -0.011 0.002 2 .43 2 .56 30-Nov-01 A < 0 . 5 m m 2.58 0.04 0.006 0.009 0.001 2.14 2.71 12-Dec-01 A > 2 m m 2.38 0.09 0 .005 -0 .004 0.002 2 .35 2 .37 12-Dec-01 A > 1 m m 2.60 0.09 0.006 -0.001 0.004 2 .48 2.59 12-Dec-01 A > 0 . 5 m m 2.45 0.04 0 .005 -0 .015 0.002 2 .38 2.40 12-Dec-01 A < 0 . 5 m m 2.70 0.04 0 .005 -0 .039 0.002 2 .57 2.60 20-Nov-01 B > 2 m m 2.28 0.04 0.006 -0 .018 0.002 2.34 2 .25 20-Nov-01 B > 1 m m 2.48 0.03 0 .005 -0 .003 0.002 2.41 2 .45 20-Nov-01 B>0 .5mm 2.41 0.11 0 .005 -0 .018 0.002 2.41 2.48 20-Nov-01 B<0 .5mm 2.55 0.04 0 .005 -0 .020 0 .003 2 .58 2.57 2 -Dec-01 B > 2 m m 2.50 0.03 0.004 -0 .015 0 .003 2 .57 2.52 2-Dec-01 B > 1 m m 2.42 0.02 0.004 -0 .029 0 .003 2 .47 2.46 2-Dec-01 B>0 .5mm 2.53 0.15 0.006 -0 .014 0.006 2 .50 2 .59 2 -Dec-01 B<0 .5mm 2.65 0.10 0.006 0.000 0.006 2.36 2 .69 11-Dec-01 B > 2 m m 2.51 0.03 0 .005 0.000 0 .003 2 .57 2 .53 11-Dec-01 B > 1 m m 2.37 0.03 0.006 0.002 0.004 2 .50 2.52 11-Dec-01 B>0 .5mm 2.53 0.20 0.007 0.032 0.007 2 .52 2 .70 11-Dec-01 B<0 .5mm 2.21 0.03 0.006 0.010 0 .004 1.82 2 .28 30-Nov-01 A > 1 m m 2.33 0.06 0.006 0 .003 0.002 2 .45 2 .43 2 -Dec-01 B>0 .5mm 2.43 0.03 0 .005 -0 .008 0 .015 2.52 2.54 11-Dec-01 B > 2 m m 2.47 0.04 0 .005 -0.011 0 .005 2 .58 2.56 13-Nov-01 A < 0 . 5 m m 2.41 0.09 0.007 0 .013 0.004 2 .43 2.57 11-Dec-01 B Bulk 2 .36 0.03 0 .005 -0 .012 0.004 2.31 2.42 A v e r a g e 2.47 0.07 0.006 -0 .002 0 .004 2.41 2.51 min 2.21 0.02 0.004 -0 .039 0.001 1.82 2 .25 m a x 2.70 0.20 0.007 0.042 0 .015 2 .58 2.71 S t .Dev . 0.10 0 .05 0.001 0.017 0 .003 0 .15 0.11 164 A P P E N D I X F Date R e a c t o r M g : P N : P M g : N S a m p l e M o l e Rat io Mo le Rat io M o l e R a 13-Nov-01 A >2mm 0.98 0.95 1.03 13-Nov-01 A > 1 m m 0.99 0.97 1.02 13-Nov-01 A > 0 . 5 m m 0.99 0.96 1.04 13-Nov-01 A < 0 . 5 m m 1.02 0.93 1.09 30-Nov-01 A >2mm 0.99 0.93 1.07 30-Nov-01 A > 1 m m 1.01 0.95 1.06 30-Nov-01 A > 0 . 5 m m 0.99 0.95 1.04 30-Nov-01 A < 0 . 5 m m 0.95 0.79 1.20 12-Dec-01 A >2mm 1.00 0.99 1.01 12-Dec-01 A > 1 m m 1.00 0.96 1.05 12-Dec-01 A > 0 . 5 m m 1.02 0.99 1.03 12-Dec-01 A < 0 . 5 m m 1.04 0.99 1.05 20-Nov-01 B > 2 m m 1.01 1.04 0.97 20-Nov-01 B > 1 m m 1.01 0.98 1.03 20-Nov-01 B>0 .5mm 0.97 0.97 1.00 20-Nov-01 B<0 .5mm 0.99 1.00 0.99 2 -Dec-01 B > 2 m m 0.99 1.02 0.97 2 -Dec-01 B > 1 m m 0.98 1.00 0.98 2 -Dec-01 B>0 .5mm 0.98 0.96 1.01 2 -Dec-01 B<0 .5mm 0.99 0.88 1.12 11-Dec-01 B > 2 m m 0.99 1.02 0.98 11-Dec-01 B > 1 m m 0.94 0.99 0.95 11-Dec-01 B>0 .5mm 0.94 0.93 1.00 11-Dec-01 B<0 .5mm 0.97 0.80 1.21 30-Nov-01 A > 1 m m 0.96 1.01 0.95 2 -Dec-01 B>0 .5mm 0.96 0.99 0.96 11-Dec-01 B > 2 m m 0.97 1.01 0.96 13-Nov-01 A < 0 . 5 m m 0.94 0.94 0.99 11-Dec-01 B Bulk 0.98 0.96 1.02 A v e r a g e 0.98 0.96 1.03 min 0.94 0.79 0.95 m a x 1.04 1.04 1.21 S t .Dev . 0 .03 0.06 0.06 165 Date R e a c t o r % M g % N % P % C a % K %AI % F e S a m p l e 13-Nov-01 A > 2 m m 9.7 5.4 12.5 0.85 0.03 0.04 0.03 13-Nov-01 A>1mm 9.3 5.3 12.1 0.92 0.04 0.01 0.02 13-Nov-01 A>0.5mm 9.7 5.4 12.4 0.75 0.04 0.18 0.04 13-N.OV-01 A<0.5mm 10.0 5.2 12.5 0.42 0.04 0.07 0.02 30-Nov-01 A >2mm 10.2 5.5 13.1 1.21 0.04 0.02 0.03 30-Nov-01 A > 1 m m 10.1 5.5 12.7 0.43 0.04 0.06 0.01 30-Nov-01 A>0.5mm 10.0 5.6 13.0 0.55 0.03 -0.05 0.02 30-Nov-01 A<0.5mm 10.6 5.1 14.2 0.28 0.04 0.04 0.01 12-Dec-01 A >2mm 10.1 5.7 12.8 0.65 0.04 -0.02 0.02 12-Dec-01 A > 1 m m 10.2 5.6 13.0 0.59 0.04 0.00 0.03 12-Dec-01 A>0.5mm 10.0 5.6 12.6 0.24 0.03 -0.07 0.02 12-Dec-01 A<0.5mm 10.5 5.8 12.9 0.23 0.03 -0.17 0.02 20-Nov-01 B > 2 m m 9.1 5.4 11.5 0.27 0.04 -0.08 0.01 20-Nov-01 B > 1 m m 10.3 5.7 12.9 0.23 0.03 -0.02 0.02 20-Nov-01 B>0.5mm 10.0 5.8 13.1 0.77 0.03 -0.08 0.02 20-Nov-01 B<0.5mm 10.0 5.8 12.8 0.25 0.03 -0.09 0.02 2 -Dec-01 B > 2 m m 9.9 5.9 12.7 0.18 0.03 -0.07 0.02 2 -Dec-01 B > 1 m m 9.9 5.8 12.8 0.17 0.03 -0.13 0.03 2 -Dec-01 B>0.5mm 10.3 5.8 13.4 0.99 0.04 -0.06 0.06 2 -Dec-01 B<0.5mm 10.8 5.5 14.0 0.66 0.04 0.00 0.05 11-Dec-01 B > 2 m m 9.9 5.8 12.7 0.22 0.03 0.00 0.03 11-Dec-01 B > 1 m m 9.7 5.9 13.2 0.20 0.04 0.01 0.04 11-Dec-01 B>0.5mm 10.0 5.8 13.6 1.27 0.04 0.14 0.07 11-Dec-01 B<0.5mm 8.8 4.2 11.6 0.21 0.04 0.04 0.04 30-Nov-01 A > 1 m m 9.6 5.8 12.8 0.42 0.04 0.01 0.02 2 -Dec-01 B>0.5mm 9.6 5.7 12.8 0.18 0.03 -0.03 0.14 11-Dec-01 B > 2 m m 9.7 5.8 12.8 0.25 0.03 -0.05 0.04 13-Nov-01 A<0.5mm 9.5 5.5 12.9 0.58 0.05 0.06 0.04 11-Dec-01 B Bulk 9.8 5.5 12.8 0.20 0.04 -0.05 0.04 A v e r a g e 9.9 5.6 12.8 0.49 0.04 -0.01 0.03 min 8.8 4.2 11.5 0.17 0.03 -0.17 0.01 m a x 10.8 5.9 14.2 1.27 0.05 0.18 0.14 S t .Dev . 0.4 0.3 0.6 0.32 0.01 0.07 0.02 A P P E N D I X G APPENDIX G: OPERATING COST ESTIMATES 167 APPENDIX G Chemical Costs Chemical cost analysis is based on calculated sodium hydroxide usage in both reactors during the th period of November 9-27 2001, and an estimate of the magnesium requirement based on equimolar dosing to supernatant phosphate content. Table Gl shows the cost calculations for sodium hydroxide and magnesium chloride. Table Gl: Chemical Cost Estimate Scenario A Scenario B Sodium Hydroxide Usage 0.37 0.17 (kg/m3 supernatant) Magnesium Chloride Usage (kg/m3 supernatant) 0.46 0.46 Supernatant Volume 32850 32850 (m3/year) Sodium Hydroxide Usage 12098 5428 (kg/year) Magnesium Chloride Usage (kg/year) 15080 15080 Supernatant Phosphate 70 70 Concentration (mg/L) % Phosphate Recovery 80 60 Mass of Struvite Produced 14533 10900 (kg/year) Sodium Hydroxide Cost 6049 2714 ($/year) Magnesium Chloride Cost 3016 3016 ($/year) Chemical Cost per kg Struvite ($/kg Struvite) 0.62 0.53 168 A P P E N D I X G Labour Costs The labor costs developed in this study are based on the following estimates. These estimates were based on the labor required to operate the pilot scale reactors and approximation of the extra labor required to operate a full scale system. The cost of labor is assumed to be $50 000 per year for 35 hours per week ($27.50/hr). Table G2 shows the estimated labor allocation for each required task. This results in a labor requirement of 1600 hours per year or 0.63 persons per day (assuming 7 hour days), which translates to $44 000 per year. Table G2: Labor requirement Estimate Task Labor Estimate Labor Estimate (hrs/year) Process Monitoring 1 hr/day 365 Lab Analysis 0.5 hrs/day 182.5 Maintenance 4 hrs/week 208 Chemical Shipping/Recieving 2 hrs/week 104 Product Struvite Handling/Shipping 2 hrs/day 730 Reactor Cleanout/Overhaul 8hrs 2x per year 16 Total - 1600 Process Savings Three sources of savings and revenues were evaluated in this study. These are revenues associated with the sale of struvite estimated at $730 / metric ton; reduction in sludge shipping cost at 62$ per truckload (City of Penticton Data) and reduction in polymer usage at estimated at $100 per day (Berne Udala, pers. comm.). During the course of the study it was estimated that the digestion of 40% of the WAS resulted in a reduction in polymer usage of approximately 50% and a reduction in sludge shipping by 9 truckloads per month according to operational records. This resulted in a cost reduction of approximately $100 per day for polymer usage and $18.34 per day for sludge shipping. The income due to struvite sale simply depends on the mass produced. 169 

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