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Phosphate recovery from greenhouse wastewater through crystallization Yi, Weigang 2003

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PHOSPHATE RECOVERY F R O M GREENHOUSE WASTEWATER THROUGH CRYSTALLIZATION By Weigang Yi B.Eng. (Environmental Engineering), Tongji University, China, 1999 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF APPLIED SCIENCE in THE FACULTY OF GRADUATE STUDIES DEPARTMENT OF CHEMICAL AND BIOLOGICAL ENGINEERING We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA January 2003 © Weigang Yi, 2003 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of 0»»'"* »fMy* ^ ^ ' ^ The University of British Columbia Vancouver, Canada Date fr* 7 , ^ DE-6 (2/88) ABSTRACT ABSTRACT An investigation was conducted on the suitablility of phosphate recovery from greenhouse wastewaters by a precipitation/crystallization process. Two groups of jar tests and five months of a pilot-scale reactor operation on site, were carried out. Greenhouse drainage wastewater contains high concentrations of phosphate, calcium, magnesium, potassium, which varies from time to time, depending on the greenhouse operation period. Results from the laboratory jar test show that more than 90% of phosphate could be removed from greenhouse wastewater. Various calcium phosphate salts were also obtained in the process, hydroxyapatite, CasCPO^OH, was the main product recovered. Phosphate removal was affected by the presence of magnesium in the wastewaters. An increase in magnesium concentration in the wastewaters decreased the phosphate removal rates. The chemical content of precipitates, in terms of calcium, magnesium and phosphate, were affected by the Ca/Mg ratio. The higher calcium content was obtained in wastewaters with the higher Ca/Mg ratios. An addition of magnesium did not affect the potassium content in the precipitates. K-struvite, MgKP04.6H20, was not the major product in the precipitate, even with addition of a large quantity of magnesium. A second group of lab jar tests was conducted, with magnesium and ammonium addition in three wastewaters of different calcium concentration wastewaters. At any operating pH, the calcium concentration was the major factor determining the phosphate removal efficiency. The addition of ammonium changed the chemical reaction at the lower pH zone (<8.0), moving toward more struvite formation, except when calcium was at a high concentration. However, hydroxyapatite was still the main product of the precipitate that formed. A pilot-scale, fluidized bed reactor was set-up and operated at South Alder Greenhouse, located in Delta, BC. The reactor was tested with two feed strengths during the study period. Results from this operation confirmed that the crystallization process could efficiently remove up to 90% of phosphate under both feed strength conditions. Operating pH and ii ABSTRACT supersaturation ratio of the wastewater were controlling parameters. Crystals obtained grew on the surface of the seeding material, and they were mainly hydroxyapatite. iii TABLE OF CONTENTS TABLE OF CONTENTS Page ABSTRACT ii TABLE OF CONTENTS iv LIST OF TABLES viii LIST OF FIGURES ix ACKNOWLEDGEMENTS xi CHAPTER 1 INTRODUCTION 1 1.1 Phosphorus Resource 1.1.1 Phosphorus in nature 1.1.2 Phosphate industry and sustainable development 1.1.3 Phosphorus in wastewater 3 5 1.2 Greenhouse Wastewater 6 1.3 Phosphorus Recovery by Crystallization 7 CHAPTER 2 OBJECTIVES 9 CHAPTER 3 BACKGROUND AND LITERATURE REVIEW 10 3.1 Calcium Phosphate Chemistry 10 3.1.1 Solubility 3.1.2 Calcium phosphate precipitation kinetics 10 11 3.2 Experiences In Calcium Phosphate Recovery 14 iv TABLE OF CONTENTS Page 3.3 Magnesium Ammonium Phosphate (MAP, Struvite) 15 3.3. I Chemical and Physical Properties 15 3.3.2 Agronomic Characteristics. 17 3.4 Experiences In Struvite Recovery 18 3.5 Magnesium Potassium Phosphate (K-Struvite). 20 3.6 Differences Of Solubility Product Value 22 3.7 Application of Crystallization To Greenhouse Wastewater 23 3.8 Conditional Solubility Product 24 3.9 Supersaturation Ratio 26 3.10 Parameters For Crystallization Process Operation 27 3. 10. 1 OperatingpH value 27 3.10.2 Calcium to magnesium molar ratio 28 3.10.3 Magnesium to phosphate molar ratio 29 3.10.4 Ammonium to phosphate molar ratio 29 3.10.5 Seeding material 29 CHAPTER 4 MATERIALS AND METHODS 31 4.1 Wastewater 31 4.2 Jar Test Design 32 4.2.1 Apparatus 3 2 4.3 Reactor Design 33. 4.3.1 Injection port 3 4 4.3.2 Reaction zone 3 7 4.3.3 Top clarifier 3 8 4.3.4 External clarifier 3 9 4.3.5 Seeding material 41 4.3.6 Greenhouse wastewater storage tank 41 4.3.7 Pumps and pH controller 42 4.3.8 Daily maintenance and sampling 43 TABLE OF CONTENTS Page 4.4 Conditional Solubility Determination 44 4.4.1 Apparatus 44 4.5 Analytical Methods 45 CHAPTER 5 RESULTS AND DISCUSSION 46 5.1 Greenhouse Wastewater Characterization 46 5.2 First Group of Jar Tests 48 5.2.1 Removal Efficiency 48 5.2.2 Chemical properties of precipitates 50 5.2.3 Summary 54 5.3 Second Group of Jar Tests 56 5.3.1 Removal Efficiency 56 5.3.2 Chemical properties of precipitates 5 9 5.3.3 Summary 66 5.4 Conditional Solubility Product Determination 68 5.5 Reactor Operation 70 5.5.1 Nutrient loading 70 5.5.2 Phosphate removal efficiency 72 5.5.3 Super saturation ratio 76 5.5.4 Flow rates 11 5.5.5 Crystal obtained 19 5.5.6 Operational problems 8 3 5.5.7 Summary 85 CHAPTER 6 CONCLUSIONS 87 CHAPTER 7 RECOMMENDATIONS 90 REFERENCES 92 APPENDIX A CALCULATIONS FOR UPFLOW VELOCITIES IN REACTOR 96 vi TABLE OF CONTENTS Page APPENDIX B CALCULATIONS FOR FLUID REYNOLDS NUMBERS IN REACTOR 97 APPENDIX C DATA FOR FIRST GROUP OF JAR TEST 99 APPENDIX D DATA FOR SECOND GROUP OF JAR TEST 112 APPENDIX E DATA FOR CONDITIONAL SOLUBILITY TEST 125 APPENDIX F DATA FOR REACTOR OPERATION 132 vii LIST OF TABLES LIST OF TABLES Page Table 1.1 Trophric states of aquatic ecosystem 2 Table 3.1 Calcium phosphates and their solubilities. 11 Table 3.2 Theoretical composition of struvites 15 Table 3.3 Composition of fertilizer grade struvites 16 Table 3.4 Theoretical composition of K-struvites 21 Table 4.1 Configurations, upflow velocity and Reynolds number in different reactor sections (Flow rate = 3.6 L/min) 38 Table 5.1 Characteristics of Greenhouse Wastewater (July 2001 To Feb. 2002) 47 Table 5.2 Characteristics of Greenhouse Wastewater (March 2002 To May 2002) 47 Table 5.3 First group jar test experimental conditions 48 Table 5.4 Precipitate mass obtained (First group of jar tests) 50 Table 5.5 Comparison of precipitate mass and mass reduction from wastewater (First group of jar tests) 54 Table 5.6 Second group jar test experimental conditions 56 Table 5.7 Comparison of precipitate mass and mass reduction from wastewater (Second group of j ar tests) 66 Table 5.8 Average results of crystal composition analysis (run 1) 81 Table 5.9 Average results of crystal composition analysis (run 2) 81 viii LIST OF FIGURES LIST OF FIGURES Page Figure 1.1 Eutrophication problem 3 Figure 1.2 Main use of phosphate 4 Figure 1.3 Life time of P2O5 reserves 5 Figure 4.1 Pilot-scale crystallization process 33 Figure 4.2 Reactor set up at South Alder Greenhouse, Delta, BC. 34 Figure 4.3 Detail design of the injection port 35 Figure 4.4 Detail design and cross section of caustic injector. 36 Figure 4.5 Detail design of reaction zone 37 Figure 4.6 Detail design of top clarifier 39 Figure 4.7 Detail design of external clarifier 40 Figure 4.8 Analytical instruments. 45 Figure 5.1 Phosphate removal vs. pH (First group of jar tests) 49 Figure 5.2 Ca, PO4, Mg, K to precipitate ratio vs. pH (First group of jar tests) 51 Figure 5.3 Average Ca, PO4, Mg, K to precipitate ratio vs. Ca/Mg molar ratio (First group of jar tests) 52 Figure 5.4 Ca/P04 molar ratio vs. pH (First group of jar tests) 53 Figure 5.5 Phosphate removal vs. pH (Second group of jar tests) 57 Figure 5.6 NH4, Mg, Ca, PO4 to precipitate vs. pH (Ca=7.6 mmol/L, Second group of jar tests) 59 Figure 5.7 Ca to PO4 molar ratio vs. pH (Ca=7.6 mmol/L, Second group of jar tests) 61 Figure 5.8 NH4, Mg, Ca, P0 4 to precipitate vs. pH (^=9.6 mmol/L, Second group of jar tests) 61 Figure 5.9 Ca to PO4 molar ratio vs. pH (Ca=9.6 mmol/L, Second group of jar tests) 63 LIST OF FIGURES Page Figure 5.10 NH4, Mg, Ca, PO4 to precipitate vs. pH (Ca=12 mmol/L, Second group of jar tests) 64 Figure 5.11 Ca to PO4 molar ratio vs. pH (Ca=12 mmol/L, Second group of jar tests) 65 Figure 5.12 Conditional solubility curve for distilled water at 25°C and 15°C, greenhouse wastewater at 25°C 69 Figure 5.13 Nutrient loading during the reactor operation period 71 Figure 5.14 Phosphate removal efficiency vs. operating pH (reactor run 1) 72 Figure 5.15 Phosphate removal efficiency vs. influent S.S. ratio (reactor run 1) 73 Figure 5.16 Phosphate removal efficiency vs. operating pH (reactor run 2) 74 Figure 5.17 Phosphate removal efficiency vs. influent S.S. ratio (reactor run 2) 75 Figure 5.18 Supersaturation ratios during the operation period (run 1) 76 Figure 5.19 Supersaturation ratios during the operation period (run 2) 77 Figure 5.20 Total flow rates during the study period (run 1) 78 Figure 5.21 Total flow rates during the study period (run 2) 79 Figure 5.22 Crystals from reactor operation (run 1) 80 Figure 5.23 Crystals from reactor operation (run 2) 82 ACKNOWLEDGEMENTS 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. • Dr. K. Victor Lo, my supervisor, sincere appreciation for his exceptionally support and encouragement throughout the entire course of this work, • Frederic Koch, the manager of the UBC phosphate recovery project, for introducing me to this wonderful and challenging project, for paving the way and continued directions, • Dr. Ping Liao, for all the valuable advices and assistances in both laboratory introduction and process operation during this study, • Dr. D. S. Mavinic and Dr. K. J. Hall, my committee members, for all the important and appreciated advices, • Dr. A. K. Lau, for the supports and being my thesis defense committee, • Gladis Lemus, my fellow student, for her immense help and being a good friend from the day I came to UBC, • Ali Adnan and Ahren Britton, my fellow students in this phosphate recovery project, for all the assistances and sharing ideas. • Juergan Pehlke, for helping me with the reactor set-up and mechanical troubles. xi ACKNOWLEDGEMENTS • William Cheuk, Raymond Wong and Jeos, managers of South Alder Greenhouse, for providing this chance to work on the greenhouse wastewater. • University of British Columbia, for giving me the opportunity to continue my studies and gaining a true learning experience. • My family and friends, for their encouragements and support throught out my degree. xii INTRODUCTION CHAPTER 1 INTRODUCTION 1.1 Phosphorus Resource 1.1.1 Phosphorus in nature Phosphorus is widely recognized as one of most important natural resource. It averages 1180 ppm in the earth crust, and thus ranks as the eleventh most common element. (Becker, 1989) Nature has taken advantage of the manifold aspects of the chemical behaviour of phosphorus, which has thus become indispensable for life. The organic phosphorus compound DNA is the backbone of the genetic code in living cells, and ATP monitors energy conversion in cells. Living creatures supply their phosphate needs by food, and phosphates in food arise from biological phosphorus uptake from available soil components. Manure from livestock and human waste, together with some other composted waste was returned to the soil, thus closing a nutrient loop and maintaining the fertility of the land. Failure to conserve the nutrients in the land for the long term needs inevitably led to impoverished soil, and poor crop yields. Nutrient conservation was not only applied to the land but also to the aquatic environment. In some medieval monasteries a rudimentary form of waste water treatment provided a rich source of nutrients for aquaculture; providing, in return, a source of protein for the community. (Brett, 1997) Naturally, the waste products were recycled to the beginning of the loop. Urbanization and large city populations remote from the areas of agriculture production have broken the nutrients recycling loop. The result has been a flow of nutrients (in the form of foods) from the countryside towards the towns and cities. But no effective method for returning those nutrients to the land has been carried out. The sewage collection network and treatment system, which were designed to protect public health, served only to make nutrient 1 INTRODUCTION losses greater. By discharging the treated wastewater into the rivers and sea, nutrients have been moved away from the soil and also caused problems of excessive nutrients in the aquatic environment, resulting in eutrophication. Eutrophication is a condition in an aquatic ecosystem where high nutrient concentrations stimulate blooms of algae (e.g., phytoplankton). Table 1.1: Trophric states of aquatic ecosystem Trophic States Oligotrophic Clear waters with little organic matter or sediment and minimum biological activity. Mesotrophic Waters with more nutrients, and therefore, more biological productivity. Eutrophic Waters extremely rich in nutrients, with high biological productivity. Some species may be choked out. Hypereutrophic Murky, highly productive waters, closest to the wetland status. Many clearwater species cannot survive. Dystrophic Low in nutrients, highly colored with dissolved humic organic material. (Not necessarily a part of the natural trophic progression.) The excessive nutrients overstimulate the growth of algae, creating conditions that interfere with the recreational use of lakes and estuaries, and the health and diversity of indigenous fish, plant, and animal populations. Algal blooms affect the system in two ways. First, they reduce water transparency, causing submerged plants to die. Because these plants provide food and shelter for aquatic creatures (such as the blue crab and summer flounder), spawning and nursery habitat is destroyed and waterfowl have less to eat when grasses die off. Second, when the algae die and decompose, oxygen can be depleted. Dissolved oxygen in the water is essential to most organisms living in the water, such as fish and crabs, (see Figure 1.1) 2 INTRODUCTION Figure 1.1: Eutrophication problem 1.1.2 Phosphate industry and sustainable development Since phosphates are unevenly distributed and not available to plants at the current levels of farming, it is the goal of the phosphate industry to supply phosphate fertilizers of the necessary quality and quantity to farmland areas throughout the world. Agriculture fertilizers and animal feed utilize 85% of the world's phosphate supply while detergents use 12%. 3 INTRODUCTION Animal feeds 5% Detergents Agricultural fertilisers 80% 12% Speciality applications 3% Figure 1.2: Main use of phosphate The commercial source of phosphate is "phosphate rock", primarily calcium phosphate in various forms, combined with a wide range of impurities. Phosphate rock can be found through out the Earth's crust but most area have a very low phosphate content. Around 38 million tonnes of phosphate, expressed as P2O5, are extracted every year. After beneficiation, the P2O5 content of most commercial phosphate rock source is in the region of 35% (Driver, 1999). And over the last twenty years, the highest grade deposits have been rapidly depleted and the quality of rock in today's market is inferior to the grade of rock before. The known reserves of phosphate rock are limited (see Figure 1.3). The resource base which could be commercially exploited at today's economics will last, at best, little more than one hundred years and could be depleted in as little as fifty years (Driver, 1999). Of more immediate concern is the increasing level of impurities in phosphate rock. As the quality of rock declines, the presence of these problematic metallic contaminants rises. The difficulties and cost of the purification process increases. In addition, the disposal of those contaminated waste may cause other environmental problems. Therefore, a new, sustainable source of high purity becomes an important issue for the phosphorus industry. 4 INTRODUCTION 0 19967 1997 2000/ 2001 2010/ 2011 2020/ 2030/ 2021 2031 2040/ 2041 2050/ 2060/ 2051 2061 2070/ 2071 1 1 ' • 2% J - ™ ] 2.5% § § f 1 3% | most likely Figure 1.3: Life time of P2O5 reserves (2%, 2.5% and 3% phosphate consumption growth rate) /. 1.3 Phosphorus in wastewater As the result of agricultural production and consumption, municipal and agriculture waste are the two major sources of phosphorus. Sludge anaerobic digester supernatant from an advanced sewage treatment plant with biological nutrient removal (BNR) system can contain high soluble phosphorus concentration. Returning this sidestream to head of the process will lead to an excessive phosphorus loading for the B N R system. To remove the excess phosphorus is necessary for these B N R treatment plants. This has been identified as one of the most promising sources for phosphorus recovery. (Yu, 2001; Woods et al., 1999) Among the consumers of phosphate fertilizer, agriculture represents the highest share. The quantities of potentially available for recovery and recycling in animal manures are significantly greater than those in municipal sewage. In U K , as much as 45,000 tonnes of phosphorus are discarded as sewage sludge or discharged to rivers as sewage treatment works effluent. A further 200,000 tonnes of phosphorus is generated by animal manures and slurries, where it can present a major disposal problem (Driver, 1999). Besides manure waste, greenhouse drainage wastewater is another agriculture waste source for phosphorus 5 INTRODUCTION recovery. For good yields, a certain amount of fertilizer is necessary for greenhouse horticulture. This results in the greenhouse wastewater having a relatively high nutrient content. Inappropriate disposal of this nutrient rich run-off may lead to environmental contamination and resource waste. 1.2 Greenhouse Wastewater The greenhouse industry is an important and growing segment of the Canadian agriculture industry. The latest official statistics (Statistics Canada Catalogue 22-202) estimate the Canadian greenhouse industry at $1711 M and the greenhouse vegetable portion at $504 M in year 2000. As an essential factor which influences greatly the growth of the crop, as well as the fruit's quantity and quality, fertilizer application is of significant importance to the greenhouse management. Every year, greenhouse industry consumes million of tonnes of fertilizer. The data from Agriculture and Agri-Food Canada shows that in the year 2000, fertilizer consumption of the whole country was 5.2 million tonnes. A typical greenhouse vegetable crop uses 7,000 - 8,000 m3/ ha of water, and 8,500 - 9,500 kg/ha of fertilizer per year. Approximately 20-25% of the nutrients in the prepared irrigation water are not utilized by the crops. Since the fertilizer cost is relatively low when compared to other production cost in greenhouse management, the excess nutrient solution is not recirculated in most cases, or just partially recycled. Discharge of this unwanted nutrient rich run-off without appropriate treatment leads to environmental pollution. In addition, a fertilizer resource is being wasted. Greenhouse wastewater contains less solid and organic materials than municipal sewage and animal manure waste. High concentrations of phosphorus, calcium, magnesium and 6 INTRODUCTION potassium make it suitable for precipitation/crystallization process to conserve this phosphorus resource. One potential problem for recovery phosphorus from greenhouse wastewater is that the water characteristics vary significantly from time to time. In any greenhouse, the fertilizer application to a crop will be optimized throughout the entire cropping season in accordance with the changing needs of the plants for nutrients. Therefore, as a function of plant age and season, the changing nutrients supply will cause the wastewater quality to fluctuate. Another factor influencing the wastewater is the absorption of nutrients by the plants. Even when the same amount of nutrient is applied to a certain area, the drainage may be variable. 1.3 Phosphorus Recovery by Crystallization At present, the most promising ways to recover phosphorus from wastewater are phosphate crystallization as calcium phosphate or struvite (magnesium ammonium phosphate), the chemistry of these two compounds is different, but the integration of their crystallization into sewage treatment and sludge handling is similar. Calcium phosphates can be recycled into industrial processes, or processed simply to locally manufacture fertilizers. Struvite can be used directly as a fertilizer, or it can be incorporated into fertilizer manufacture. As it's analogous potassium compound, K-struvite (Magnesium potassium phosphate) is isostructural with struvite. And the substitution of NFfV" by the smaller K produces only minor structural changes (Mathew, 1979). It is reasonable to expect that K-struvite might be another option for phosphate recovery. Crystallization is a separation and purification process employed to produce a wide variety of material. It can be loosely defined as the controlled precipitation of selected substances in crystalline form from solution (Giesen, 1999). Compared to the removal technique, phosphorus recovery by using precipitation/crystallization process can offer many potential benefits. As mentioned above, phosphate recovered from waste as re-useable end products, 7 INTRODUCTION calcium phosphate, struvite and K-struvite, could considerably reduce the reliance on non-renewable mined phosphate resource, moving phosphorus towards sustainability. In addition, it reduces the sludge production and the associated disposal cost. 8 OBJECTIVES CHAPTER 2 OBJECTIVES World-wide research has developed phosphate crystallization techniques to recover phosphorus from wastewater, in the form of calcium phosphate and struvite, especially from domestic wastewater. Agriculture waste, greenhouse drainage wastewater in this case, is another potentially important source for phosphorus. However, very little research has been undertaken in this field, and little information can be found in treating this particular type of wastewater. The main purpose of this study was to obtain reaction knowledge of phosphate precipitation/crystallization process in greenhouse wastewater and to investigate the potential of phosphorus recovery by using a three-phase column pilot-scale reactor developed by the UBC Civil Engineering environmental group. The specific objectives of this study were: 1. To investigate the possibility of employing crystallization process for phosphorus recovery from greenhouse drainage wastewater. 2. To evaluate the possible phosphate removal efficiency from lab scale jar testing. 3. To provide the phosphate compounds formation knowledge in greenhouse waste-water under different conditions. 4. To provide the crystal conditional solubility information 5. To evaluate the P removal efficiency in pilot-scale reactor operation conditions. 6. To determine the controlling parameters for reactor operation. 7. To investigate other factors for the crystallization process. 9 BACKGROUND AND LITERATURE REVIEW CHAPTER 3 BACKGROUND AND LITERATURE REVIEW 3.1 Calcium Phosphate Chemistry Calcium phosphate is essentially the same material as the mined phosphate rock used as feedstock by the phosphate and fertilizer industries worldwide, so it can readily be accepted into industrial processed for recycling, subject to obtaining an appropriate material quality (reasonably high phosphate content, limited levels of certain heavy metal contaminants, low water and organics content, good physical and handling properties.) 3.LI Solubility Solubility represents a measure of the concentration in solution necessary for a phase to precipitate. Solubility product is equilibrium constant for a reaction involving precipitation and it's constituent ions. For example, for tricalcium phosphate, that ionize as follows: Ca3(P04)2 o 3 Ca 2 + +2 P043" Eq. 1 The solubility product expression is [Ca2+]3[P043"]2 = Ksp Eq. 2 Phosphate precipitation occurs when its component ions reached saturation. However, when high ionic strength is presented in wastewater, the free ion concentration contributing to saturation will be lower than the total ion concentration, and thus significant supersaturation will be necessary for precipitation. The degree of supersaturation required can be predicted theoretically, or assessed experimentally. 10 BACKGROUND AND LITERATURE REVIEW In calcium and phosphate solutions, various calcium phosphate salts may form depending on the pH and solution composition. They include dicalcium phosphate, tricalcium phosphate, octocalcium phosphate and hydroxyapatite etc (Table 3.1, Nancollas, 1984). As a result, calcium phosphate saturation will depend on the phase closest to saturation at the prevailing solution conditions. However, the precipitated phase will most likely eventually transform into the thermodynamically more stable hydroxyapatite (HAP) (Kibalczyc 1989). Table 3.1: Calcium phosphates and their solubilities. Formula Compound Solubility product Ca5(P04)3OH Hydroxyapatite (HAP) 4.7xlfJ59 Ca4H(P04)3.2.5H20 Octacalcium phosphate (OCP) 1.25xl0"47 Ca3(P04)2 Tricalcium phosphate (TCP) ~ CaHP04.2H20 Brushite or dicalcium phosphate dihydrate (DCPD) 2.49xl0"7 CaHP04 Monetite (DCPA) (anhydrous DCPD) 1.26X10-7 Ca3(P04)2 Amorphous calcium phosphate (ACP) 1.20xl0"29 3.1.2 Calcium phosphate precipitation kinetics Kinetics of phosphate precipitation assists reactor design and operation by providing information of the rate of new phases formation, and thus can help optimize detention time and precipitation conditions. There are two steps formation by precipitation from solution: nucleation and growth. In a supersaturated solution, for nucleation to occur, the newly formed nuclei have to exceed a critical size. Precipitation can take place in several different ways: homogeneous nucleation, which refers to the spontaneous growth of individual crystallites in solution, or heterogeneous nucleation, crystallites aggregation on existing surfaces like seed crystals. 11 BACKGROUND AND LITERATURE REVIEW Heterogeneous nucleation is less energy demanding, and a better analogue for wastewater environments where a multitude of surfaces exist, such as suspended particles. Epitaxial growth, where the newly formed crystals nucleate on a seed phase of different structure requires a suitable crystal lattice match between the two phases, particularly if the degree of supersaturation is low. (Nancollas, 1984) Transport from the bulk solution to the nuclei surface, followed by adsorption to the surface and a number of steps through which the location of the newly adsorbed species changes on the surface to gain an energetically favorable position. Kinetic factors are general believed to be more important in determining the nature, and the characteristics of the phases formed during the precipitation process than equilibrium considerations. That means the most thermodynamically stable phase may not precipitate, because its precipitation kinetics are slow; an alternative less stable phase, able to nucleate faster, may precipitate instead, or precipitation may not happen at all, or not until an appropriate "trigger" (seeding) becomes available. Complications may also arise from the formation of mixed solid phases resulting from the overgrowth of one crystalline phase onto another. (Valsami-Jones, 2001) Calcium phosphate kinetics suggests that a precursor phase will precipitate from supersaturated solutions, but this will eventually recrystallize to form HAP. The precursor phase may be dicalcium phosphate dihydrate (DCPD), octacalcium phosphate (OCP), tricalcium phosphate (TCP) or an amorphous calcium phosphate (ACP) depending on the conditions (Kibalczyc, 1989; Meyer, 1983; Nancollas, 1984). The kinetic of calcium phosphate precipitation is complicate. Several researches have tried to establish the specific conditions and order of formation of the precursor phases, but the results from different studies are variable. Zawacki et al. (1990) observed a nucleation of calcium deficient HAP on HAP seeds by using the constant composition method, while Barone et al. (1976) using a pH-stating method, observed a precipitation of DCPD onto the 12 BACKGROUND AND LITERATURE REVIEW HAP seeding crystals. Freche (1992) and Heughebaert (1986) observed the precipitation of OCP and DCPD onto seed crystals of OCP and DCPD, but not hydroxyapatite. Amorphous calcium phosphate (ACP) is suggested to be the precursor phase when pH>7 and high supersaturated. The ACP may dissolve again and forms HAP nuclei (Bosky, 1973). A three stage formation of hydroxylapatite starting with the formation of ACP, followed by OCP, has also been suggested. Kibalczyc (1990) using a pH drift-method, observed a transformation of one type of ACP into another ACP, which then transformed into HAP, at a pH-range of 7.0-9.0. He concluded that under such experimental conditions OCP was not a possible precursor phase to HAP. In addition, precipitation of non-stoichiometric apatites has also been observed (Heughebaert et al., 1986,1990; Zawacki et al., 1990). A number of ions have been shown to act as inhibitors to precipitating phases, by forming a surface complex on the newly forming surfaces, and blocking further precipitation. The influence of magnesium has been discussed by many authors. Co-precipitation of magnesium with the calcium phosphates for example may induce firstly the formation of ACP, which will transform into the more stable HAP. It is possible for HAP to incorporate a small percentage of magnesium into its structure, but this causes structural changes and has an inhibitory effect to further HAP formation (Kibalczyc et al., 1990). Studies from Heughebaert et al., (1990) and Zawacki et al., (1990) also show that HAP often precipitates in a non-stoichiometric form. 13 BACKGROUND AND LITERATURE REVIEW 3.2 Experiences In Calcium Phosphate Recovery Researchers and water companies have developed several reactors for recovering phosphate from wastewater in calcium phosphate forms. However, most of current working systems are variations of fluidized bed using seeding material, such as sand grains. The influent enters the reactor from below keeping the bed of sand grains fluidized. In order to reach supersaturation for crystallization to take place, a pH increase by alkaline solution addition or CO2 stripping and the addition of other ions (calcium or magnesium) are necessary. Different calcium phosphate phases may precipitate. Problems with fines and non-recycle quality precipitates have been reported. (Seckler, 1994) The DHV Crystallactor™ process is a fluidized reactor in which calcium phosphate crystallizes on a seeding grain, typically sand. The process conditions are adjusted by adding lime (Ca(OH)2). Full-scale Crystallactor™ unite have been operated at three sites in The Netherlands (two sewage works, one food industry factory). The high rate of crystallization allows a short retention time, and thus a small reactor size. In practice, a surface load is 40 m/h and reactor height of 4 m are used (Brett et al., 1997). During operation the pellets increase in diameter, and on reaching the desired size, are removed and replaced by smaller diameter seed grain. This allows continuous operation and ensures good fluidization. The calcium phosphates recovered from a full scale Crystallactor™ operating at Geestmetambacht offer good handing properties and around 11% phosphorus content. They are currently transported to the Thermphos factory at Vlissingen, The Netherlands, and are being recycled into industrial phosphate production. The Kurita Fixed Bed Crystallization Column is based on similar chemistry to the DHV Crystallactor™. It is designed to remove phosphate from the secondary effluent of a sewage treatment plant by use of phosphate rock seeding grains, without the production of sludge. Calcium chloride and caustic soda are fed into the reactor to ensure suitable conditions. The recovered product is hydroxyapatite. 14 BACKGROUND AND LITERATURE REVIEW 3.3 Magnesium Ammonium Phosphate (MAP, Struvite) Struvite is magnesium ammonium phosphate hexahydrate with the chemical formula MgNH4P04.6H20. It is crystallised by the reaction of magnesium ion (Mg2+), ammonium ion (NH4+), and orthophosphate ion (HPO42") on an equal mole basis. Mg 2 + + NH4+ + HPO42" + OH - + 6 H 2 0 -» MgNH4P04.6H20 + H 2 0 Eq. 3 Its pure form is a white crystalline powder, but it can also occur either as large single crystals, very small crystals, large curds or a gelatinous mass. Its specific gravity is 1.7. It is only slightly soluble in water. This suggests it can be used as a non-burning and long-lasting source of nitrogen, phosphorus, and metal. It is present in certain natural fertilizer such as Guano. When properly granulated, MAP is non-burning to plants even when applied at extremely high rates, and it can be used to supply plant nutrients over predetermined periods of time by control of the particle size. It can be used effectively for either soil or foliar application. This special property makes it particularly suitable for use where conventional fertilizers are insufficient, burning is a problem, and long residual effects are desired. Applications include fertilization of ornamentals, orchards, nurseries, forest out plantings, turfs, highway plantings, certain other crops, and seed coating (Bridger et al., 1962). 3.3.1 Chemical and Physical Properties Struvite composition is listed in Table 3.2 (Bridger et al., 1962). The monohydrate is of more interest for fertilizer use because of its higher analyses and greater stability. Table 3.2: Theoretical composition of struvites Mol. Wt. % N % P 2 0 5 % Mg (% MgO) % Ignition loss MgNH4P04.6H20 245.43 5.71 28.92 9.91 (16.43) 54.65 MgNH4P04.H20 155.35 9.02 45.69 15.65 (25.95) 28.36 15 BACKGROUND AND LITERATURE REVIEW The availability of phosphate in fertilizer grade struvite was determined by, the A O . A C . ammonium citrate method (Table 3.3 Bridger et al., 1962). It indicates that approximately 97% of the P2O5 in magnesium ammonium phosphate monohydrate is available. Table 3.3: Composition of fertilizer grade struvites „. X T % Total % N P 2 0 5 % Avail. P2O5 %Mg (% MgO) %F % Moisture at 100 °C MgNH4P04.H20 8.3 44.6 43.1 14.8 (24.6) 0.5 1.0 Although magnesium ammonium phosphate monohydrate is soluble in ammonium citrate solution, the P2O5 availability as determined by the A O . A C . method varies from batch to batch depending on purity, crystal size, and degree of hydration. The availability of the hexahydrate, either reagent or fertilizer grade, is substantially 100%. It is higher than that of the monohydrate because of greater dilution with water of crystallization that decreased the ratio of P2O5 to solvent in the analytical determination. Magnesium ammonium phosphate monohydrate gradually hydrates to the hexahydrate when it contacts soil moisture at ambient temperatures. Therefore, under cool moist climatic conditions all the P2O5 in magnesium ammonium phosphate monohydrate becomes available. Magnesium ammonium phosphate monohydrate is much more stable than the hexahydrate. The hexahydrate gradually loses ammonia even in 35°C. The hygroscopicity of the monohydrate is also much lower than that of the hexahydrate. (Bridger et al, 1962) 16 BACKGROUND AND LITERATURE REVIEW 3.3.2 Agronomic Characteristics. Magnesium ammonium phosphate has been used as a fertilize work with many varieties of turf grasses, tree seedings, ornamental plants, truck crops, field crops, flowers, and citrus. Most of the results reported were on soils where magnesium was not believed to be a critical factor. Differences in yield can generally be attributed to the nitrogen and phosphate. The response of many varieties in forest nurseries has been excellent. The convenience of a single application either mixed with the soil at the time of seeding or top-dressed is a distinct advantage. The amount used in top-dressing can be varied so that the single application lasts for one or two years. Reports show that the length and oven-dry weight of terminal growth of balsam fir in a nursery bed fertilized with magnesium ammonium phosphate were twice as great as that of one growing season (Bridger et al., 1962). Red spruces were four times as great. White pine, American holly, multi-flora rose, Norway spruce, slash pine, Douglas fir, and several other varieties fertilized with magnesium ammonium phosphate in nursery beds had a much darker color and more growth than those treated with conventional materials. A potato experiment was conducted for testing struvite as a source of magnesium. In soils where magnesium was deficient, mixed fertilizers were formulated with magnesium ammonium phosphate, conventional materials with soluble magnesium, and conventional materials without magnesium. While the conventional mixture with soluble magnesium gave 20% more marketable potatoes than without magnesium, the mixture with magnesium ammonium phosphate gave 42% more marketable potatoes. (Bridger et al., 1962) Additional yield from the magnesium ammonium phosphate was probably at least partially due to the presence of the slowly available nitrogen in this mixture. 17 BACKGROUND AND LITERATURE REVIEW 3.4 Experiences In Struvite Recovery Processes have been investigated to recovery struvite on bench, pilot and full scale. Reactor conditions are controlled by changing pH through NaOH or Mg(OH)2 dosing or/and aeration of the liquors, as well as increasing constituent ions concentration, usually magnesium. Typical processes use fluidized bed reactor or pellet reactors, where the material is collected as small solid pellets. The Unitika Phosnix Process is one successfully system based on struvite crystallization from an enriched phosphate stream in Japan. Three full-scale struvite recovery unites are currently operational at sewage treatment plants, two of which have been in place since 1998 (500 m3/day and 150 m3/day) and since 2000 (500 mVday). The Phosnix process treats the filter supernatant from the sludge anaerobic digestion of a 45,000 m3/day biological nutrient removal sewage works (Ueno and Fujii, 2001). The reactors were installed because the released phosphate in the sludge digestion supernatant being returned to the head of the sewage treatment plant, resulted in ineffective phosphorus removal. It also generates less sludge which has a high disposal cost. In Phosnix process, magnesium hydroxide and sodium hydroxide are used. Magnesium hydroxide is added to serve both function of adjusting pH and increasing magnesium concentration. However, in order to reduce the chemical dose cost and adjust the remainder of pH, carbon dioxide stripping and addition of sodium hydroxide were also used. Operation Mg/P ratio is about 1. And the phosphorus removal efficiency is about 90%, thus enable the whole sewage treatment plant to achieve P discharge standards. Crystals grow to a size of 0.5 to 1 mm, in ten days retention time (Ueno and FujiL, 2001). The Unitika Phosnix reactor produces 500-550 kg struvite per day which is sold to a fertilizer company for 250 Euros/tonne, with transport costs covered by the purchaser. The recovered struvite is sold as a premium value fertilizer for rice and vegetable cultivation. Two fertilizer companies market this product and emphasis in the advertising that it is an environmental 18 BACKGROUND AND LITERATURE REVIEW recycled product ("Green MAP"). The fertilizer, after mixing with other products to provide a potassium content, is sold for 100-200 Euros per 20 kg bag to the public (Ueno and Fujii, 2001). In Italy, Battistoni's research (1997, 1998, 2000, 2001) shows that struvite crystallization can be done without the addition of chemicals. The fluidized bed reactor achieves more than 80% removal of phosphorus from belt press liquors, from a biological nutrient removal treatment plant with anaerobic digestion. Air stripping removed carbon dioxide and raises the pH from 7.9 to 8.3-8.6. The presence of a fairly high concentration of calcium (200 mg/L) in the stream resulted in an end product that is the mixture of struvite, hydroxyapatite, and calcium carbonate. Another pilot scale reactor operating in Hiagari sewage treatment plant in Kitakyushu, Japan, uses seawater as a magnesium source to reduce the magnesium dosage cost. (Matsumiya et al, 2000) This fluidized bed struvite crystallization reactor treated sidestream liquor from sludge dewatering machine. Without chemical addition, the phosphorus removal efficiency is about 70% depending on the influent pH and hydraulic retention time. The seawater used as magnesium source contained 1250 mg/L of Mg 2 + . The ratio of Mg/P was controlled at 1.5. The pellets obtained are about 1 mm in diameter, and their chemical content is similar to theoretical value of struvite. 19 BACKGROUND AND LITERATURE REVIEW 3.5 Magnesium Potassium Phosphate (K-Struvite). Similar to struvite, magnesium potassium phosphate is a white powder, and only slightly soluble in water. The solubility products were reported of 2.4x10"11 for MgKP0 46H 20 (Taylor et al., 1963). It can be used as a non-burning and long-lasting fertilizer. Magnesium potassium phosphate is a very efficient source of both potash and phosphate. Good growth response was reported with tomatoes, rye grass, and other crops. Response depended on granule size making it possible to tailor potassium and phosphorus supply for a given crop or cropping period. The soluble salt level in soils was reduced by using MgKP04.H-20, rather than the usual potash sources. It is similar both physically and chemically to magnesium ammonium phosphate. This is because the ammonium ion and potassium ion are approximately the same size, 1.42 °A and 1.33 °A, respectively. MgKP04.6H20 is isostructural with struvite, MgNH4P04.6H20, and the substitution of NH4+ by the smaller K produces only minor structural changes (Mathew and Schroeder, 1979). The rate of release of nutrients from magnesium ammonium phosphate and magnesium potassium phosphate is different from particles of the same size. This is probably due to the fact that the rate of release of nitrogen from magnesium ammonium phosphate is affected by nitrifying bacteria, whereas the potassium salt does not have this type of microbial breakdown (Salutsky and Steiger, 1964). Table 3.4 lists the molecular weights, and theoretical compositions of the K-Struvite (Salutsky and Steiger, 1964). It has three forms containing 0, 1, and 6 moles of water of crystallization. 20 BACKGROUND AND LITERATURE REVIEW Table 3.4: Theoretical composition of K-struvites Mol. Wt. % K %K 20 %P % P 2 0 5 % Mg (% MgO) MgKP0 4.6H 20 266.491 14.67 17.67 11.64 26.64 9.13 (15.13) MgKP0 4.H 20 176.411 22.17 26.70 17.59 40.23 13.79 (22.86) MgKP0 4 158.395 24.69 29.74 19.59 44.81 15.35 (25.46) K-struvites is considerably less stable compared to the ammonium compound. Magnesium potassium phosphate slowly disproportionates in water to trimagnesium phosphate and potassium phosphate. The phosphate availability of K-Struvite closely parallel that of the MAP as determined by the standard A.O.A.C. ammonium citrate analytical method. Although the potassium in the magnesium potassium phosphates is insoluble in water, solubility is high in ammonium oxalate solution under the conditions of standard A.O.A.C. method for determining K (K20) availability (Salutsky and Steiger, 1964). Magnesium potassium phosphate is thermally stable in the anhydrous form. The hydrated compounds lose water when heated to form the anhydrous compound. The MgKP0 4.6H 20 shows no tendency during its thermal decomposition to form the monohydrate or any other lower hydrate, but yields the anhydrous compound at a considerably lower temperature than is possible by ignition of MgKP0 4.H 20. Magnesium potassium phosphate dissolves incongruently. It has been reported (Salutsky and Steiger, .1964) that MgKP0 4.H 20 and MgKP0 4.6H 20 are partially hydrolysed in water over a long period of time to K 3 P O 4 and Mg3(P04)2.22H20. When MgKP0 4.H 20 is added to water, it slowly hydrates to form the hexahydrate: MgKP0 4,H 20 + 5 H 2 0 -> MgKP0 4.6H 20 Eq. 4 21 BACKGROUND AND LITERATURE REVIEW The rate of hydration is slow, taking several days for completion. The hexahydrate slowly disproportionates according to the following equation: The monohydrate was partially converted to hexahydrate after 45 hours of digestion and almost completely converted after 94 hours. 3.6 Differences Of Solubility Product Value As mention in Section 3.1.1, the solubility product is the equilibrium constant for a reaction involving precipitation and it's constituent ions. When crystals of a compound are placed in water, the ions at the surface dispense in the water, and will continue to do so until the salt is completely dissolved or a condition of saturation is attained. With so-called insoluble substances, the saturation value is very small and is reached quickly. The equilibrium that exists between crystals of a compound in the solid state and its ions in solution is amenable to consideration under the equilibrium relationship and can be treated mathematically as though the equilibrium were homogeneous in nature. Given a equilibrium where, 3 MgKP0 4.6H 20 + 4 H 2 0 -> K 3 P0 4 + Mg3(P04)2.22H20 Eq. 5 XmYn o mX-n + nY' -m Eq. 6 The solubility can be expressed Ksp = [X" n]m[ Y- m ] n Eq. 7 22 BACKGROUND AND LITERATURE REVIEW And pKsp is defined as pKsp = - logio Ksp Eq. 8 Experiment for calculation of solubility product can be either formation or dissolution of pure precipitate in deionized water and under rigidly controlled conditions, such as temperature, mixing energy and ionic strength. Reported values of pKsp for hydroxyapatitie and struvite differ by several order of magnitude. Hydroxyapatite pKsp claimed by Nancollas (1984) is 58.6, while Ferguson's study (1973) shows it varies from 52 to 55. Dastur (2001) stated struvite pKsp differs by 5 orders of magnitude from 9.41 to 14.1. The reasons for this may be summed up as: lack of a standard method to determined Ksp (Webb and Ho, 1992); lack to knowing the actual chemical reaction occurred (Buchanan et al., 1994; Burns and Finlayson, 1982) and how much time needed to reach equilibrium (Borgerding 1972; Abbdna et al., 1982; Burns and Finlayson 1982); neglecting the effect of ion activities and other thermodynamic considerations (Snoeyink and Jenkins 1980; Taylor et al., 1963; Webb and Ho, 1992). 3.7 Application of Crystallization To Greenhouse Wastewater Greenhouse drainage wastewater is a nutrient enrich stream. It contains a high concentration of calcium, magnesium, potassium and phosphate. Most of nitrogen supply for the plants is in the form of nitrate. It can be reasonably expected the end product from crystallization process is the mixture of calcium phosphate and other less soluble salts. 23 BACKGROUND AND LITERATURE REVIEW Calcium is one of the major constituents in greenhouse drainage wastewater with very high concentration of above 400 mg/L. No doubt it will precipitate out with phosphate from the wastewater solution. Among several forms of calcium phosphate, hydroxyapatite (HAP), Cas^O^OH, with the highest pKsp value, is most likely the major product in the mixture. The research done by Battistoni (1997, 1998, 2000, 2001) and Abbona (1986) show that the prevalent salt formed was HAP and MAP. It is also reported by Battistoni (3) that the Ca/P04 and Mg/P04 molar ratios strictly influence the molar percentage of MAP or HAP formed, while a Mg enriched supernatant (Ca/Mg=1.8) gives a MAP formation ranging from 80 to 100% in his FBR reactor with the quartz sand seed. Due to the small concentration of ammonia and the high concentration of potassium (180 mg/L) in the greenhouse wastewater, K-struvite (MgKP04.6H20) could be one of these salts As mentioned in section 3.5, K-Struvite, MgKP04.6H20 is isostructural with struvite, MgNH4P04.6H20. The solubility of MgKP04.6H20 in water, diluted HC1, and NaOH is slightly higher than the corresponding magnesium ammonia phosphates. The solubility products were reported of 7.1xl0"13 for M g M L o ^ ^ O and 2.4xl0-11 for MgKP04.6H20 by Taylor (1963). And it is also less stable than the struvite. One of the differences, K-Struvite dissolves incongruently. It slowly disproportionates in water to trimagnesium phosphate and potassium phosphate. 3.8 Conditional Solubility Product The expected mixture product from greenhouse wastewater crystallization process and all those uncertainty problems about the solubility product make it impossible to employ solubility product as the control parameter for this research project. A practical parameter that can overcome the complexities in the real world becomes necessary for applying 24 BACKGROUND AND LITERATURE REVIEW crystallization in greenhouse wastewater treatment. The concept of "conditional solubility product" was introduced. The condition constant is defined as an equilibrium constant that holds only under a given set of experimental conditions (Stumm and Morgan, 1981). It gives a relationship between elements that are of direct interest. In the equilibrium example we discuss above, XmYn <^> mX"° + nY"m Eq. 6 The conditional solubility product could be expressed, — Y mV ' 1 a ~ ^ total 1 total Ksp cc xccYy xyY Eq. 9 where Ps = conditional solubility product Xtotai, Ytotai - analytical total molar concentration of the anion and cation of the salt respecticely, irrespective of the form they may be present in, a = ionization fraction of respective components y = activity coefficient for respective ion species 25 BACKGROUND AND LITERATURE REVIEW 3.9 Supersaturation Ratio The supersaturation ratio (SSR) can be used to quantify the precipitation potential of a compound (Snoeyink and Jenkins, 1980; Stumm and Morgan, 1981). Supersaturation ratio can be defined as, Ps SSR = Ps.eq Ps.eq = condition solubility product at equilibrium Theoretically, SSR > 1 means the system is supersaturated and precipitation is possible, SSR = 1 means the system is at an equilibrium condition, SSR < 1 means the system is undersaturated and precipitation is not possible. Eq. 10 Because Ps-eq is pH dependent, for the salt like calcium phosphate or struvite, increasing pH will decrease Ps-eq value, thus increasing SSR ratio and leading to precipitation. The same result can be obtained by increasing the concentration of any constituent ions (increasing the Ps). A supersaturation solution crystallizes moving to equilibrium. As discussed in Section 3.1.2 calcium phosphate precipitation kinetics, comprises two stages, nucleation and crystal growth. By the definition from Mullin's Crystallization (2001), metastable zone is between the unsaturated and supersaturated zone, where spontaneous crystallization is improbable, however, when a crystal seed in placed in such a metastable solution, growth would occurs. The ideal crystallization process control should be done in this metastable zone. 26 BACKGROUND AND LITERATURE REVIEW 3.10 Control Parameters For The Crystallization Process Operation Supersaturation ratio is obvious the major control parameter for crystallization process. The pH, temperature, the concentration of constituent ions in solution and the recycle ratio are all important precipitation variables to control. By changing one or more of these factors, supersaturation ratio can be manipulated to a certain point to achieve more efficient precipitation. From the practical engineering point of view, there are some other parameters that need to be considered. In this particular phosphate crystallization process, calcium to magnesium ratio, magnesium to phosphate ratio, and ammonium to phosphate ratio were reported by many authors to be important. Other considerations are more about reactor design, including turbulence, hydraulic retention time and seeding materials. 3.10.1 Operating pH value Calcium phosphate, struvite and K-struvite are insoluble in alkaline pH. Precipitation can be achieved by raising the pH to reach supersaturation. This is generally accepted by all researchers and executed in almost all the reactor operation. The desired pH can be obtained by caustic dosage or/and carbon dioxide stripping. Besides the labor costs, caustic dosage is the main operating expense for precipitation-crystallization process. Therefore, many efforts have been put into reducing the caustic addition, such as by using lime or magnesium hydroxide instead of sodium hydroxide, and carbon dioxide stripping. Calcium hydroxide, usually called lime, was used for many calcium phosphate precipitation cases. It is cheaper than sodium hydroxide and serves the purpose well. But in the case of struvite crystallization, high calcium phosphate will lead the reaction to precipitate calcium phosphate and reduced the struvite content in the end product. 27 BACKGROUND AND LITERATURE REVIEW Magnesium hydroxide is also cheaper and has the advantage of raising the pH and increasing the magnesium concentration in solution at the same time. However, the requirement for optimizing both parameters independently needs process combining magnesium hydroxide and other caustic addition, such as sodium hydroxide. As discussed in Section 3.4, the Phosnix process operates successfully with magnesium hydroxide, sodium hydroxide and CO2 stripping. Carbon dioxide stripping is another useful way to stimulate crystallization. In the solution with high CO2 concentration, air stripping can be used to reduce or even eliminate the caustic dosage and save operating cost. In addition, agitation caused by pumping air through the solution in the reactor can serve another function, increasing the turbulence and crystal collision. Battistoni's researches (1997, 1998, 2000, 2001) achieved satisfactory results only by using CO2 stripping without caustic dosage. 3.10.2 Calcium to magnesium molar ratio In cases where calcium phosphate and struvite both precipitated from the wastewater stream, the calcium to magnesium ratio might play an important role determining proportion of these two end products. In Abbona's paper (1986), when the Ca fraction to [P]=[Ca]+[Mg] is more than 0.1-0.2, the calcium phosphates dominate at low pH, whereas struvite can occur in the precipitate only at high pH. Also, Battistoni (1998) shows that when Ca/Mg ratio is about 3.6, the mixture of hydroxyapatite and struvite molar ratio is 65/35, and a Mg enriched supernatant with Ca/Mg ratio of 1.8 gives a struvite formation of 80 to 100%. An inverse result was also reported when operated with a Ca+ enriched supernatant. Even when magnesium presents just a little amount in a calcium phosphate dominating reaction, it inhibits the calcium phosphate precipitation and decreases the overall phosphate removal efficiency. 28 BACKGROUND AND LITERATURE REVIEW 3.10.3 Magnesium to phosphate molar ratio Magnesium concentration in solution is considered as a controlling factor for struvite crystallization when ammonium concentration is high enough in the sewage treatment plant supernatant sidestream. Struvite crystallization studies (Adnan, 2002) show that phosphate removal efficiency increases with a higher Mg/P molar ratio. Also it requires a ratio of over 1.5 to achieve 70% phosphate removal. (Matsumiya, 2000) Magnesium chloride is normally added as a magnesium source. Matsumiya (2000) used seawater for a pilot scale struvite crystallization reactor and produced relatively pure MAP pellets. 3.10.4 Ammonium to phosphate molar ratio Due to the high ammonium concentration in either sewage or animal wastewater, ammonium to phosphate ratio has never been considered as a limiting factor for the crystallization process. Thus, not much research has been reported on studies of N/P molar ratio. Only Munch (2001) stated phosphate removal improved with higher ammonium concentration. For greenhouse wastewater, ammonium is present at low level in the solution. Calcium phosphate was expected to be the main product in the mixture. However, struvite or K-struvite is a more valuable fertilizer. There is a possibility to move the reaction toward struvite crystallization, if combining greenhouse drainage water with other cheap ammonia source, like animal manure wastewater. 3.10.5 Seeding material Most of the phosphate crystallization use fluidized bed reactor, and seeding becomes essential in this type of system. Kinetic suggests crystallization process being controlled in the metastable zone is the key for a successful operation. In the metastable zone, spontaneous nucleation rate was reduced, and crystal growth was encouraged. Seeding material provides the surface needed for crystal growth, avoiding the inherent lag period. 29 BACKGROUND AND LITERATURE REVIEW Kinetic studies of calcium phosphate precipitation used different forms of calcium phosphate as the seeding material, such as hydroxyapatite, brushite and octacalcium phosphate. Full scale DHV Crystallactor™ system and pilot scale fluidized bed reactor from Battistoni (2001) used sand, while the Kurita process is seeded with nature phosphate rocks, which is hydroxyapatite. For struvite crystallization, researchers chose struvite pellets as a seeding material. 30 MATERIALS AND METHODS CHAPTER 4 MATERIALS AND METHODS The study was carried out in three parts: jar tests, conditional solubility determination and pilot scale reactor operation. The first and second groups of jar tests were finished in October 2001 and May 2002, respectively. Jar tests and conditional solubility determination for the mixture product were conducted in the Water and Wastewater analyses Laboratory, Bio-Resource Engineering, UBC. A pilot scale three phases fluidized bed reactor was set up and operated from December 2001 to May 2002, at South Alder Greenhouse, Delta. The reactor was designed based on the previous experiments done at the UBC Environmental Engineering Pilot Plant. 4.1 Wastewater The wastewater used in this study was from South Alder Greenhouse, a pepper growing greenhouse operation located in Delta, B.C. It has a drainage water containing a high concentration of the nutrients of calcium, potassium, magnesium, nitrate, sulfate, phosphate and other trace ions. In the South Alder Greenhouse, this nutrient enriched stream was collected from the cropping field and stored in a storage tank for partial recirculation back to irrigation. The greenhouse drainage wastewater contains less solid and organic materials, but the water quality varies significantly from time to time. From October 2001 to February 2002, phosphate concentration fluctuated from 37 mg/L to 93 mg/L. After the new cropping season started in March, phosphate was up to 200 mg/L. The same situation happened to all other nutrients. 31 MATERIALS AND METHODS 4.2 Jar Test Design From the original wastewater data from the greenhouse owner, we know that nutrients concentrations vary significantly. Since no similar research has never been done in this area with the greenhouse waste, it was necessary to run the jar tests to obtain necessary reaction information, to evaluate the assumption that magnesium to calcium ratio and ammonium addition can affect the composition of the mixed crystal product and to determine the initial operating conditions. Two groups of jar testes were conducted under different pH conditions, Ca/Mg ratio and ammonium concentration at room temperature (20 °C). The first group of ten sets of jar tests was carried out under a range of pH from 7.5 to 9.5 and molar ratios of Ca/Mg from 0.28 to 3.58 without ammonium addition. The second group of eleven jar tests with pH from 6.76 to 8.94, Ca/Mg molar ratio from 0.92 to 2.85, and NH4/PO4 molar ratio from 1.43 to 18.76. 4.2.1 Apparatus The apparatus used for jar test experiment was a six stations paddle stirrer (Phipps and Bird). The 700 ml beakers containing 500 ml greenhouse wastewater were stirred at 20 rpm for one hour and then allowed to settle for another hour. The supernatant was decanted and filtered with 4.5 u microfiber filter, and then was acidified and kept at 4 °C. The crystals were either oven dried at 36 °C for one day or air dried for two days after they were centrifuged. In order to determine the content of crystals, they were re-dissolved in water and digested with acid, filtered and kept at 4 °C until they were taken for analysis. The wastewater was prepared by adding the MgCL, solution to achieve the desired Ca/Mg molar ratio, NH4CI solution to raise NH4 concentration, and the pH was adjusted using dilute HC1 and NaOH solution. 32 MATERIALS AND METHODS 4.3 Reactor Design Based on the result of first group jar test and the bench, pilot scale reactor operation experience at the UBC Environmental Engineering Pilot Plant, a pilot scale three phases reactor were set up and operated from December 2001 to May 2002, at South Alder Greenhouse, Delta, B.C. The reactor was designed by the UBC Phosphate Recovery Group. It is a fluidized bed reactor with three increasing diameter sections with a clarifier zone on the top. The process set up and images are presented in Figure 4.1 and Figure 4.2. Greenhouse wastewater and recycle stream from the external clarifier was fed to the bottom of the reactor. The different diameters give a different up flow velocity and turbulence in these sections, and separate the particles by size. Top clarifier External clarifier Effluent Recycle stream MasterFlex Peristaltic pump Recycle pump Greenhouse Wastewater Storage tank Feed pump PROCESS SET UP Figure 4.1: Pilot-scale crystallization process 33 MATERIALS AND METHODS Figure 4.2: Reactor set up at South Alder Greenhouse, Delta, BC. Left: fluidized bed reactor, control box and caustic solution storage tank; top right: greenhouse drainage wastewater storage tank; bottom right: reactor control box with feed, recycle and MasterFlex pumps, as well as pH controller and monitor. 4.3.1 Injection port The reactor injection port was designed to mix the greenhouse wastewater, recycle stream from external clarifier, the sodium hydroxide solution addition controlled by the pH controller and possibly magnesium chloride solution from MasterFlex dosing pump. Figure 4.3 shows the detailed design of the injection port. The caustic and magnesium injection port was constructed of stainless steel to prevent corrosion due to the sodium hydroxide solution. 34 MATERIALS AND METHODS 13 mm * 40 mm ID Caustic and Mg injectors a . A - A V I E W Feed 1 Ball valve 2 Qucik release connector In-reactor sampling port Recyle stream INJECTION PORT Figure 4.3: Detail design of the injection port The diameter of wastewater feed and recycle stream injection port is 13 mm, while that of the caustic and magnesium injection was 2.4 mm. Figure 4.4 shows the detail design and cross section image of caustic injector. Due to the small size of this injection port, feed stream and caustic injection were well blended and enter the reaction zone after. However, high supersaturation condition in this area caused encrustation and plugging problem. Regular cleaning was necessary during the reactor operation. The plugging problem depended on both the operational conditions and the intermittent caustic injection from the pH controller. When the reactor was running at a high pH or high supersaturation condition, plugging could be very severe, and led to complete blockage and failure of pH control. 35 M A T E R I A L S AND METHODS Quick release connector 9.7 mm ID LDPE tubing Quick release connector m o 9.7 mm ID LDPE tubing B-B VIEW 13 mm ID High turbulence zone NaOH from pH controller diaphragm pump 2.4 mm ID Injectors MgCl or NaOH from MasterFlex peristaltic pump Stainless steel Influent CAUSTIC INJECTORS Figure 4.4: Detail design and cross section of caustic injector. In order to avoid the plugging problem, another caustic injection design was developed. In greenhouse wastewater, magnesium concentration is high at 57 to 158 mg/L. From the results of first jar test, it is not the limiting factor for the process. Therefore, the Masterflex peristaltic dosing pump, which was originally designed for magnesium addition, was used for caustic dosage in the later operation. By providing a constant flow of sodium hydroxide solution, the pH control was achieved and plugging situation was reduced. The caustic injection port was cleaned with a welding rod every other day or every three days. Also quick released connectors were used for the purpose of easily disconnection of injection port from the reactor. 36 MATERIALS AND METHODS 4.3.2 Reaction zone The three phase reaction zone is located above the injection zone. It was built of transparent PVC (polyvinyl chloride) piping connected with standard Schedule 40 or Schedule 80 PVC fitting. The transparent piping was used in order to monitor the behavior of crystal formation in the fluidized bed and encrustation problem. Detail design shown in Figure 4.5. C-C VIEW To pH Controller Ball valve 3 pH Control probe 40 mm ID L = 450 mm First section Ball valve 2 Ball valve 4 A 52 mm ID L = 600 mm Second section 40 mm * 52 mm PVC pipe 77 mm ID L = 720 mm Third section 52 mm * 77 mm REACTION ZONE Figure 4.5: Detail design of reaction zone The inside diameter of three phases were 40 mm, 52 mm and 77 mm respectively from the bottom to the top. The inside diameter, length, volume, as well as Reynolds number of these three sections were listed in Table 4.1. Notice that the Reynolds number in the table were hydraulic calculations with a flow of 3.5 liter/min without seeding or crystal formation. Calculations of upflow velocity and Reynolds number in different flow rate condition can be found in Appendix A and B. The actual Reynolds number of this type of fluidized bed 37 MATERIALS AND METHODS reactor with seeding and growing crystal would be significantly different from the calculation value of water flow. Table 4.1: Configurations, upflow velocity and Reynolds number in different reactor sections (Flow rate = 3.6 L/min) Upflow Reactor section Diameter Length Volume velocity Reynolds number cm cm L cm/min First section 4 45 0.57 277.8 2074 Second section 5.2 60 1.27 165.1 1603 Third section 7.7 72 3.36 75.1 1080 Top clarifier 20.5 26 8.58 10.6 406 With this design, crystals can be separated in different sections due to the high to low up flow velocity. Large crystals will stay in the bottom section, while fine particles could be trapped by the seeding or grown crystal or retained in the reactor due to the low velocities of the upper sections. A high velocity at this section also increases the chance of particle collision, in benefit of increasing the density of crystals. Therefore, the bottom section of the reaction zone was also served as the harvest zone. The pH monitor and control probe was place at the top of the harvest zone of the reactor. Ball valves (including one between injection port and reaction zone, one between reaction zone and top clarifier) were used to separate these sections for the controlling purpose. 4.3.3 Top clarifier The top clarifier is mounted on the top of the reaction zone. It was made of transparent acrylic pipe. The inside diameter of this top clarifier is 205 mm and the height was 350 mm. Three outlets were designed for effluent, overflow and drainage purposes respectively. The effluent outlet was set at 260 mm water depth. The overflow outlet was at 310 mm water 38 MATERIALS AND METHODS depth. The drainage outlet was close to the bottom of the clarifier, at 30 mm water depth. Figure 4.6 shows the design of the top clarifier. 0205mm — n Effluent outlet 350 mm 310 m m 260 mm To External Clarifier Reaction zone TOP CLARIFIER Figure 4.6: Detail design of top clarifier The effluent outlet was connected to the external clarifier by a vertical 25 mm inside diameter transparent PVC pipe tipped with a 31 mm inside diameter flexible tubing. The overflow was connected to the external clarifier by a 12.7 mm outside diameter LDPE (Low Density Polyethylene) tubing. Siphon breakers were set on both these outlets. 4.3.4 External clarifier The external clarifier was used as an effluent storage vessel to recycle part of the effluent from the top clarifier back to the reactor injection port. It had a 305 mm diameter round surface with a cone shape bottom of approximate 60° slope. The height of the cone shape 39 MATERIALS AND METHODS bottom section was 330 mm. The water depth of the cylinder section was 350 mm, with a freeboard of 100 mm. Figure 4.7 shows the design of the external clarifier. The recycle flow was pumped from an outlet on the side of the clarifier 200 mm below the water level. The recycle stream tubing was 12.7 mm outside diameter LDPE tubing. A three ways valve was set at the effluent outlet for flow measurement. The effluent was drained to the greenhouse drainage system by a hose. A sludge drain valve was place at the bottom of the cone shape section for collecting and removing the accumulated sludge in the clarifier. 0 305 mm Clamp To pH Monitor To Power outlet To Recycle pump Dainage outlet pH Monitor probe Drainage hose Three ways valve Effluent outlet _ 450 mm 350 mm 150 mm 1 EXTERNAL CLARIFIER Figure 4.7: Detail design of external clarifier 40 MATERIALS AND METHODS The 31 mm diameter flexible tubing mentioned in Section 4.3.3 from the top clarifier was placed in a U shape with the submerged exit in the upwards vertical position on the external clarifier wall, opposite the recycle and effluent outlet. The low water level sensor was used to protect the recycling pump. A pH probe was also place at the water surface for pH monitoring. 4.3.5 Seeding material During the operation in December 2001, reactor was tested without seeding material. From January to May 2002, the mixture precipitate obtained from the sludge in the external clarifier was used as the seeding material for reactor operation. They were dried and crushed into different size particles and seeded back into the reactor. As discussed in the previous Section 3.1-3.4, seeding material for calcium phosphate recovery could use hydroxyapatite, phosphate rock or some other forms of calcium phosphate salt, and struvite crystallization use mostly struvite itself for seeding. In this particular case with greenhouse wastewater containing high concentration of calcium, magnesium, potassium and phosphate, it was considered better to seed the reactor with its possible end product. 4.3.6 Greenhouse wastewater storage tank The drainage wastewater from the pepper-growing field in South Alder Greenhouse was kept in a storage tank. Part of it was recirculated for irrigation, and the rest was pumped to a constructed wetland. The feed wastewater for this experiment was taken from this tank. The storage tank had a capacity of 65,000 liters. The feed wastewater used for the reactor was pumped from a fitting located approximate 600 mm above the storage tank bottom. The 12.7 mm outside diameter LDPE tubing was connected from the tank to the feed pump. A full tank volume of wastewater could last more than one month's reactor operation. 41 MATERIALS AND METHODS However, since the wastewater hydraulic retention time in this tank varied from 2 days in the summer season to more than 10 days in the winter, nutrient concentrations fluctuated and led to the crystallization process control difficulties. 4.3.7 Pumps and pH controller The feed wastewater pump was a Moyno Model 500 331 progressive cavity pump with a Vz HP motor and adjustable drive speed. The recycle stream was pumped using a Moyno Model 500 332 progressive cavity pump, with a Vi HP motor and adjustable drive speed as well. The MasterFlex L/S variable speed peristaltic pump and a standard pump head were originally designed for the magnesium chloride solution injection to the reactor. But since magnesium concentration was not the limiting factor for the process, the MasterFlex pump was used for providing a continuous caustic dosage, to avoid the severe plugging problem in the later reactor operation. The inside reactor pH monitor and control was a Black-Stone BL 7916 pH pump control system with an Oakton gel-epoxy probe. As mentioned in Section 4.3.2, the pH probe was placed at the top of the harvest section of the reactor. The reason for putting the probe at this position was to avoid encrustation interfering with pH readings. The pH level inside the reactor was adjusted by using the sodium hydroxide (caustic soda) solution. The sodium hydroxide solution was made up on site from industrial grade sodium hydroxide pellets (PrairieChem Inc.). The solution was stored in a 220 liters bulk liquor storage tank. The pH in the external clarifier was monitored by using an Oakton continuous pH monitor, with an Oakton gel-epoxy pH probe placed at the external clarifier water surface. 42 MATERIALS AND METHODS Both pH probes were calibrated (if necessary) every two or three days. Standard pH 7 and pH 10 buffer solutions were used when calibration, as manufactory's instructions for two point calibration. 4.3.8 Daily maintenance and sampling Several parameters were monitored and recorded every two or three days to characterize the reactor operation. Effluent flow and total flow through the reactor (influent and recycle) were measured by using a graduate and a stopwatch. Effluent flow rate was measured through the drainage from the external clarifier. The total flow rate was measured from the down pipe between reactor to the external clarifier. Influent flow equals to the effluent flow regardless of the recycle stream flow rate. Recycle flow rate was calculated from the difference of total flow and influent flow rate. The pH levels inside reactor and in the external clarifier were recorded every maintenance day. Probe calibrations were performed if necessary. Temperature was measured and recorded every half-month. Conductivity was measured by using a Hanna Instruments HI9033 multi-range conductivity meter every month. Injection port cleaning was also performed every maintenance day. Sample from the storage tank before entering the reactor, inside reactor sample after blending with recycle stream and effluent water sample were collected before making any change every maintenance day. The samples were filtered with 4.5 u microfiber filter, and then was acidified and kept at 4 °C. 43 MATERIALS AND METHODS 4.4 Conditional Solubility Determination Since there is no similar reported research and conditional solubility data available, a new conditional solubility curve developed from the crystal mixture was obtained to evaluate and analyze the reactor performance. To generate the conditional solubility curve, the end product from the reactor operation was dissolved in distilled water and greenhouse wastewater solution in different temperatures. The equilibrium solutions were analyzed for pH, ortho-phosphate, dissolved calcium, magnesium, potassium and ammonium concentrations. Three curves were developed for this practical reactor operation analysis. They were in distilled water with temperature of 15°C and 25°C, in greenhouse wastewater solution with temperature of 25°C. 4.4.1 Apparatus The apparatus used for conditional solubility determination was a six stations paddle stirrer (Phipps and Bird). The square jar contained 1.5 liters solution (distill water or greenhouse wastewater) was immersed in a constant temperature bath at 15°C and 25°C, respectively. About 1.5 gram of mixture crystal was added into each jar. The paddles stirred at 70 fpm. Equilibrium was assumed to be reached 24 hours after condition was changed. This assumption was based on previous research done by Phosphate Recovery Group, UBC. The solution pH was adjusted using dilute HC1 and NaOH solution. After 24 hours, the pH and conductivity in each jar was measured and recorded. The equilibrium solution was filtered through a 4.5 u microfiber filter, and then was acidified and kept at 4 °C until analysis. 44 M A T E R I A L S AND METHODS 4.5 Analytical Methods The samples were analysed for ortho-phosphate, ammonium, calcium, magnesium and potassium concentrations in Water and Wastewater Analyses Lab, Bio-Resource Engineering, UBC. The concentration of ortho-phosphate and ammonium were analyzed using an Automated Ion Analyzer (The Lachate QuickChem® FIA+, Zellwegar Analytic, Inc.). The methods were based on QuickChem® METHOD 10-107-06-1-A and 10-115-01-1-A respectively. The analysis techniques used are in accordance with AP.H.A Standard Methods based on the absorbance recorded at different wavelengths. Metal contents such as calcium, magnesium and potassium were determined by inductively coupled plasma-optical emission spectrometry (ICP-OES) method with Liberty 100/200 ICP-OES Spectrometer (Varian Australia Pty. Ltd.). (Figure 4.8) Figure 4.8: Analytical instruments. Top: Liberty 100/200 ICP-OES Spectrometer: Bottom: Lachate QuickChem® FIA+ Automated Ion Analyzer. 45 RESULTS AND DISCUSSION CHAPTER 5 RESULTS AND DISCUSSION This study includes Greenhouse wastewater characterization, Jar test with magnesium addition, Jar test with magnesium and ammonium additions, Conditional Solubility Determination and Reactor operation. 5.1 Greenhouse Wastewater Characterization Throughout the study period, the composition of the greenhouse drainage wastewater varied significantly, as expected. It can be divided into two categories. From July 2001 to February 2002, phosphate concentration fluctuated from 37 mg/L to 93 mg/L. After the new cropping season started in March, phosphate was up to 200 mg/L. The first 4 samples were taken in July 2001, and analyzed in the Environmental Lab, Civil Engineering, UBC. Three more batches of wastewater used for the jar test were collected in September and October. A total 8 Samples were taken before the MgCb solution dosage in every jar test run. During the reactor operation from December 6, 2001 to February 13, 2002, 24 feed wastewater samples were collected and analyzed in Water and Wastewater analyses Lab, Bio-Resource Engineering, UBC. The characteristic of greenhouse wastewater in this period of time is shown in Table 5.1. It had very high concentration of calcium, magnesium and potassium, varying from 288.1 to 496.9 mg/L, 54 to 92.3 mg/L, and 160.7 to 200.1 mg/L, respectively. Based on the average PO4 content in the wastewater, they surpass the stoichiometric demand of calcium for hydroxyapatite HAP, or magnesium, potassium for K-struvite formations. (Ca/ P04= 16.04, Mg/ PO4 = 4.97 and K/ P04= 6.16). There was no need for additional chemical dosage. The pH ranged from 6.5 to 6.8. 46 RESULTS AND DISCUSSION Table 5.1: Characteristics of Greenhouse Wastewater (July 2001 to Feb. 2002) Parameters Unit Average Min. Max. SD. pH 6.65 6.50 6.80 0.07 P04-P mg/L 56.7 37.9 93.6 18.2 Ca mg/L 356 288 496 85.6 Mg mg/L 63.1 54.0 92.3 17.8 K mg/L 168 160 200 12.4 Ca/Mg mol/mol 3.32 3.14 4.00 0.28 Ca/P04 mol/mol 16.0 11.5 23.1 2.94 Mg/P04 mol/mol 4.97 3.56 5.77 0.91 K/PQ4 mol/mol 6_16 4/71 7.53 0.80 After the new pepper-growing season started in March, the nutrient concentration in the drainage wastewater increased dramatically. The concentration of phosphate ranges from 110 to 259mg/L. (Table 5.2) The increased nutrient concentrations change the greenhouse drainage to another type of wastewater, in terms of chemical precipitation reaction. This leads to the difficulties of process understanding and operation. Table 5.2: Characteristics of Greenhouse Wastewater (March 2002 to May 2002) Parameters Unit Average Min. Max. SD. pH 6.45 6.32 6.65 0.11 P04-P mg/L 189 110 259 49.9 Ca mg/L 459 376 531 45.3 Mg mg/L 134 99.4 163.4 23.2 K mg/L 308 182 449 90.2 Ca/Mg mol/mol 2.23 1.75 3.04 0.48 Ca/P04 mol/mol 6.31 3.44 10.6 2.23 Mg/P04 mol/mol 2.98 1.79 4.37 0.84 K/PQ4 mol/mol 437 233 9.77 2.43 47 RESULTS AND DISCUSSION 5.2 First Group of Jar Tests The first group of jar tests was conducted in October 2001 to investigate the precipitation reaction, possible end product properties and the operational condition previous to the reactor operation. Ten sets of experiments were tested in this part of study. They could be divided according to Ca/Mg molar ratio (Table 5.3). Detailed data can be found in Appendix C. Table 5.3: First group of jar test experimental conditions pH Set 1 Ca/Mg-3.58 7.5 8.0 8.5 8.5 9.0 9.5 Set 2 Ca/Mg = 3.41 7.5 8.0 8.5 8.5 9.0 9.5 Set 3 Ca/Mg = 3.27 7.5 7.8 8.0 8.3 8.7 9.0 Set 4 Ca/Mg = 3.23 7.75 7.96 8.09 8.38 8.88 9.35 Set 5 Ca/Mg = 1.84 7.63 7.91 8.01 8.29 8.65 , 8.90 Set 6 Ca/Mg = 1.32 7.54 7.73 8.07 8.31 8.76 9.18 Set 7 Ca/Mg = 1.24 7.5 7.8 8.0 8.3 8.7 9.0 Set 8 Ca/Mg = 0.73 7.5 7.8 8.0 8.3 8.7 9.0 Set 9 Ca/Mg = 0.54 7.5 7.8 8.0 8.3 8.7 9.0 Set 10 Ca/Mg = 0.28 7.5 7.8 8.0 8.3 8.7 9.0 5.2.1 Removal Efficiency Phosphate removal from wastewater was very high (Figure 5.1). As expected, an increase in the pH of the solution increased the phosphate removal efficiencies. More than 90% of phosphate was removed when the pH was higher than 8.3, regardless of Ca/Mg molar ratio. When the pH was less than 8.3, the effect of Ca/Mg molar ratio on removal efficiency was pronounced. At low Ca/Mg molar ratios, the phosphate removal rate reached as low as 14.6%. An increase in the Ca/Mg molar ratio increased phosphate removal. These results indicated that more magnesium ions in the wastewater reduced phosphate removal efficiency. The results were similar to the findings by Abbona et al. (1986) and Fugerson et al. (1973) They stated that magnesium ions affected calcium phosphate precipitation in calcium solutions. 48 RESULTS AND DISCUSSION 100.00 90.00 "= 80.00 1 7 ° ° ° g 60.00 Q. 50.00 40.00 7.3 7.6 7.9 - r - f • Ca/Mg>3 Poly. (Ca/Mg>3) y = -16.927X2 + 307.47X -1297.1 * R2 = 0.9712 8 2 pFf5 8.8 9.1 9.4 9.7 100.00 90.00 ^ 80.00 > 70.00 o | 60.00 OL ^ 50.00 o Q_ 40.00 30.00 20.00 7.2 * 1<Ca/Mg<3 Poly. (1<Ca/Mg<3) • s / • • y = -30.532X2 + 544.37X - 2328.8 R2 = 0.8959 1 I I I I 1 7.5 7.8 8.1 PH 8.4 8.7 9.3 100.00 Figure 5.1: Phosphate removal vs. pH (First group of jar tests) 49 RESULTS AND DISCUSSION The total amount of precipitate is also tabulated in Table 5.4. More precipitate was obtained in the higher operating pH. At low pH and low Ca/Mg ratio, only very small amount of precipitate was obtained. An increase of magnesium ion in wastewater decreased not only the yield of calcium phosphates, but also the total amounts of precipitate. This result was the same as Ferguson (1973) reported in his research that magnesium addition decreased phosphate removal (and calcium phosphate precipitation). Table 5.4: Precipitate mass obtained (First group of jar tests) pH Ca/Mg Ratio 7.5 7.8 8 8.3 8.7 9 Precipitate Mass (mg) Ca/Mg>3 22.0 35.5 37.7 68.5 85.8 50.5 KCa/Mg<3 15.2 35.8 42.2 67.8 60.3 96.4 Ca/Mg<l 4.5 20.2 22.4 56.5 79.2 81.6 5.2.2 Chemical properties of precipitates Figure 5.2 refers to calcium, phosphate, magnesium and potassium mass percentages in precipitate versus pH. At a given Ca/Mg ratio, the chemical content of precipitate in terms of calcium, magnesium and phosphate, were not affected by the operating pH. However, the content in the precipitate was affected by the Ca/Mg ratio. The calcium to precipitate percentages were in the range of 15% (Ca/Mg<l) to 25% (Ca/Mg>3), and not affected by the pH adjusted from 7.5 to 9.5. This trend also appeared in the phosphate and magnesium percentage graphs. The phosphate to precipitate percentage ranged from 21% (Ca/Mg<l) to 28% (Ca/Mg>3). The magnesium to precipitate figures seemed to be steadier under the condition of Ca/Mg molar ratio higher than one. No significant change was observed when the pH was raised. The potassium to precipitate figure showed K-struvite only presents in the mixture crystal by a very small portion, and more magnesium addition did not help its formation. 50 RESULTS AND DISCUSSION 35.00 30.00 25.00 •2 20.00 co •§"15.00 -9-1000 CO ° 5.00 0.00 7.3 • t 7.6 7.9 8.2 PH 8.5 8.8 • Ca/Mg>3 • 1<Ca/Mg<3 A Ca/Mg<1 9.1 9.4 45.00 40.00 Sf? 35.00 •g 30.00 % 25.00 2 20.00 Q. o 0_ 15.00 10.00 5.00 0.00 7.3 • • • • • Ca/Mg>3 • 1<Ca/Mg<3 ACa/Mg<1 A i t •!•—1 • % 7.6 7.9 8.2 pH 8.5 8.8 9.1 9.4 2.50 2.00 co •£* o. 'o CO 1— .a. 1.50 1.00 0.50 0.00 7.3 T • Ca/Mg>3 • 1<Ca/Mg<3 • Ca/Mg<1 • I 7.6 7.9 8.2 8.5 PH 8.8 9.1 9.4 Figure 5.2: Ca, PO4, Mg to precipitate ratio vs. pH (First group of jar tests) 51 RESULTS AND DISCUSSION Since pH was not a factor in the constituent distribution in the precipitate, the average calcium, phosphate, magnesium and potassium to precipitate percentage of each set of jar test runs was calculated. This was plotted versus the Ca/Mg molar ratio in a wide range from 0.28 to 3.85. (Figure 5.3) 0.8201x 3 - 6.6584X2 + 18.519x +6.5299 = 0.8573 0.5 1 1.5 2 2.5 3 Ca/Mg (mol) 3.5 8.00 0.00 -0.5596X3 + 4.1472X2 - 9.9705x + 9.1475 0.5 1 1.5 2 2.5 3 Ca/Mg (mol) 3.5 • • 1.3839X3 - 9.3336X2 + 20.028X + 13.116 0.5 1.5 2 2.5 Ca/Mg (mol) 3.5 1.20 o 0.90 & o.6o o | - 0.30 0.00 • • • y = 0.0599X3 - 0.328X2 + 0.6212x + 0.2273 R2 = 0.6771 I 1 I I 0.5 1 1.5 2 2.5 Ca/Mg (mol) 3.5 Figure 5.3: Average Ca, PO4, Mg, K to precipitate ratio vs. Ca/Mg molar ratio (First group of jar tests) The potassium percentage was under 1%, meaning that K-struvite would not be able to precipitate out as the main product, even when a high concentration of magnesium was added to the greenhouse wastewater. The magnesium percentages increased rapidly where the Ca/Mg ratio was lower than 1.8, but they were still under 8%. At the same time, the other two compounds had very similar trend lines, with calcium and phosphate percentages dropping from 23 to 10 % and 28 to 17%, respectively. Overdosed magnesium will only seriously affect hydroxyapatite (HAP) formation and thus affect phosphate removal efficiency, but did not increase K-struvite formation. 52 RESULTS AND DISCUSSION In order to have a better understanding of the precipitate formation, the calcium to phosphate molar ratio versus pH was analyzed and plotted. The stoichiometric ratios of calcium to phosphate in the precipitates were in a range of 1.6 to 3.0 (Figure 5.4). The Ca/P04 molar ratios were near or exceeding the stoichiometric ratio for hydroxyapatite (FLAP) formation. The ratio for HAP is 1.67, while the other salts of calcium phosphates are all less than this. Based on the analysis of the stoichiometric ratio of Ca/P04 in the precipitates, it was suggested that hydroxyapatite was the main product of these precipitates. ,_ 2.00 TO | 1.80 O 1 6 0 • • • V W m * • t • A mm m m • * f mm A A A A • * A A A A • Ca/Mg>3 • 1<Ca/Mg<3 ACa/Mg<1 7.3 7.6 7.9 8.2 8.5 8.8 9.1 9.4 PH Figure 5.4: Ca/P04 molar ratio vs. pH (First group of jar test) At low pH regions (less than 7.7), the average ratios were around 1.6, regardless of the amounts of magnesium in the solution. Calcium phosphate salts precipitated first at low pH. With an increase in the operating pH, the ratio of Ca/P04 in the precipitates increased. At a pH higher than 8.7, the average ratio reached 2.2 when Ca/Mg ratio was more than 3. This indicated that calcium was predisposed to form compounds other than phosphate products. This was also reflected in the mass balance between solids recovery and mass reduction from the wastewater (Table 5.5). At a high pH (more than 8), a significant discrepancy between recovery and reduction was observed. Calcium might have combined with other anions such as carbonate to precipitate out. At a high pH, various calcium and magnesium compounds 53 RESULTS AND DISCUSSION will be formed. The potassium to phosphate molar ratio was under 0.12 throughout the entire experiment. This proved that K-struvite could not be the realistic targeted product from this process. Table 5.5: Comparison of precipitate mass and mass reduction from wastewater (First group of jar tests) PH Precipitate (mg) A Mass Ca, Mg, K, P04 (mg) Set 4 7.75 35.5 38.4 Ca/Mg=3.23 7.96 56.5 46.4 8.09 57.1 58.8 8.38 74.9 54.0 8.88 85.8 59.5 9.35 90.5 64.4 Set 5 7.63 8.7 37.1 Ca/Mg-1.84 7.91 32.5 61.0 8.01 43.4 58.6 8.29 81 71.8 8.65 70.8 86.8 8.9 120.7 95.9 Set 8 7.5 12.4 16.0 Ca/Mg=0.73 7.8 31.4 31.9 8 31.1 31.7 8.3 63.4 41.7 8.7 71.3 53.1 9 73.5 54.2 5.2.3 Summary The results indicated that this phosphate crystallization/precipitation process would be an efficient way to recover phosphate from the greenhouse wastewater. More than 90% of the phosphate could be removed from greenhouse wastewater. Hydroxyapatite (HAP), Ca5(P04)30H could be the main product from the precipitates. Phosphate removal was affected by the addition of magnesium, showing a decrease phosphate removal rates. At a given Ca/Mg ratio, the chemical content of precipitate in terms of calcium, magnesium and phosphate was not affected by the operating pH. The content in the precipitates was 54 RESULTS AND DISCUSSION affected by the Ca/Mg ratio. The higher calcium contents were obtained with the high Ca/Mg ratio. An addition of magnesium did not affect the potassium content in the precipitates. K-struvite was not the major product in the precipitate, even with addition of a large quantity of magnesium. 55 RESULTS AND DISCUSSION 5.3 Second Group of Jar Tests The second group of jar tests was carried out from April to May, 2002, with three different calcium concentration greenhouse wastewaters. Eleven sets of experiments were conducted with magnesium and ammonium addition in the pH range of 6.76 to 8.94. Detail data of this section study can be found in Appendix D, with the results showing that the main factor for changing the chemical reaction was calcium concentrations. The discussion here was divided according to three calcium concentrations of 304 mg/L (7.6 mmol/L), 384 mg/L (9.6 mmol/L) and 480 mg/L (12 mmol/L). The experimental conditions are listed in Table 5.6. Table 5.6: Second group jar test experimental conditions pH Set 11 N/P= =3.52 7.65 7.86 8.33 8.61 8.88 8.94 Ca=7.6mmol, Set 12 N/P= =9.85 7.72 8.02 8.18 8.47 8.83 8.86 Ca/Mg=2.84 Set 13 N/P= =18.76 7.-64 7.79 8.05 8.31 8.67 8.79 Ca=9.6mmol, Set 14N/P= =3.35 6.97 7.18 7.6 8.01 8.31 8.71 Ca/Mg=2.15 Set 15N/P= =5.52 6.73 6.87 7.07 7.25 7.79 8.45 Setl6N/P= =2.0 6.99 7.2 7.54 7.81 8.13 8.5 Ca=12mmol, Set 17 N/P= =2.54 7.02 7.31 7.67 8.17 8.4 8.71 Ca/Mg=1.8 Set 18N/P= =4.3 6.95 7.3 7.74 8.01 8.42 8.74 Set 19N/P-=1.43 6.76 7.02 7.4 7.65 8.16 8.59 Ca=9.6mmol, Set 20 N/P= =3.92 6.81 6.99 7.3 7.65 8.08 8.66 Ca/Mg=0.93 Set21N/P= =4.95 6.88 7.05 7.32 7.78 8.23 8.72 5.3.1 Removal Efficiency Phosphate removal efficiencies in this group of jar tests still remained very high, either the same or even higher than the first group. This is shown in Figure 5.5. The reason for these higher efficiencies was the increased phosphate and calcium concentration. 56 RESULTS AND DISCUSSION 100.00 90.00 80.00 70.00 60.00 50.00 40.00 30.00 20.00 10.00 0.00 y = -50.478X2 + 886.04X - 3791.4 = 0.9836 • Ca=7.6mmol/L, P=0.38mmol/L, Ca/Mg=2.84, N/P=3.52-18.76 6.5 6.8 7.1 7.4 7.7 pH 8 8.3 8.6 8.9 9.2 • Ca=9.6mmol/L, P=2.7mmol/L, Ca/Mg=2.15, N/P=3.35-5.52 • Ca=9.6mmol/L, P=2.7mmol/L, Ca/Mg=0.93, N/P=1.43-4.95 7.1 7.4 7.7 pH 8 9.2 100.00 90.00 80.00 0 s 70.00 15 > o 60.00 E 50.00 or 40.00 o 30.00 Q. 20.00 10.00 0.00 6.5 y = -20.196X2 + 338.65X -1319.8 R = 0.9863 • Ca=12mmol/L, P=1.18mmol/L, Ca/Mg=1.8, N/P=2-4.3 6.8 7.1 7.4 7.7 pH8 8.3 8.6 8.9 9.2 Figure 5.5: Phosphate removal vs. pH (Second group of jar tests) 57 RESULTS AND DISCUSSION From set 11 to set 13, the nutrient condition was similar to the type of wastewater used in the first group of jar tests. The calcium concentration was 304 mg/L (7.6 mmol/L). Therefore the treatment efficiency was similar. More than 90% of the phosphate was removed, when the pH was higher than 8.4, regardless of N/P molar ratio. A phosphate removal of 60% was achieved at a pH of 7.95. When the calcium concentration was increased to 384 mg/L (9.6 mmol/L), the phosphate removal trend line shifted to the low pH zone. This means that in the low pH zone, the process can achieve high phosphate removal. More than 90% of phosphate removal was found when the pH was above 7.9, and 60% phosphate was removed when the pH was 7.3. The Mg/Ca molar ratios of 2.15 and 0.93, made no difference to the removal efficiency. Under the conditions with high calcium concentration of 480 mg/L (12 mmol/L), the same removal efficiency was obtained at the lower pH. A phosphate removal of 90% was achieved at pH 7.7, versus 60% at pH 7.0. All of the jar test phosphate removal efficiencies were not a function of N/P molar ratio or Ca/Mg molar ratio. The phosphate concentration did not affect the result. The precipitation process with high calcium (12 mmol/L) but medium phosphate (1.18 mmol/L), resulted in a higher phosphate removal than the one with medium calcium (9.6 mmol/L) and high phosphate (2.7 mmol/L). The total ion strength showed no effect on the phosphate removal efficiency. Total ion strength was calculated with calcium, phosphate, magnesium, ammonium and potassium molar concentrations. Under the high calcium condition with an ion strength of 5.1xl0"12, phosphate removal efficiency was higher than that in the medium calcium concentration, but with high ion strength of 3.1xlO"u. The main factor dominating the removal was the calcium concentration. 58 RESULTS AND DISCUSSION 5.3.2 Chemical properties of precipitates The precipitates obtained were dissolves in acid solution for the analysis of chemical contents. Low calcium concentration condition Figure 5.6 showed the ammonium, calcium, phosphate and magnesium distributions in the precipitate, in the low calcium concentration condition. In the low calcium concentration condition (Ca=304 mg/L, 7.6 mmol/L), which is similar to the first group of jar tests, the result from experiments with ammonium addition was different (see Section 5.2.2). Due to the presence of NFL;4", at a given Ca/Mg ratio, the precipitate chemical content in terms of calcium, phosphate and ammonium were affected by the operating pH in the low and high area, below 8.0 and above 8.8, respectively. • • N/P=3.52 • N/P=9.85 AN/P=18.76 • • A * • B A A . " * • * • 7.5 7.8 8.1 pH8.4 8.7 9 9.3 5.00 ^ 4.00 a> I 3.00 Q. <j> 2.00 CL J ? 1.00 0.00 7.5 • • N/P=3.52 • N/P=9.85 A AN/P=18.76 • • A • • t • * A • 7.8 8.1 PH 8.4 8.7 9.3 40.00 £ 35.00 £ 30.00 TO •5. 25.00 g 20.00 5- 15.00 TO O 10.00 5.00 A " * A . A . A • "A • •» • w • N/P=3.52 • N/P=9.85 AN/P=18.76 • 1 I 1 1 7.5 7.8 8.1 pH8.4 8.7 9.3 35.00 2= 30.00 1 25.00 20.00 £ 15.00 Q. g 10.00 5.00 0.00 • " J L A * • • N/P=3.52 • • N/P=9.85 AN/P=18.76 • 1 1 7.5 7.8 8.1 pH 8.4 8.7 9.3 Figure 5.6: NFL, Mg, Ca, P O 4 to precipitate vs. pH (Ca=7.6 mmol/L, Second group of jar tests) 59 RESULTS AND DISCUSSION Under this condition, ammonium was present at a high percentage in the precipitate, in the low pH area. The ammonium dosage amount affected these trends when the pH was lower than 8.0. With the high N/P molar ratio of 18.76, the ammonium percentage in precipitate reach as high as 11% at pH 7.8. In the jar test with a low N/P ratio of 3.52, it was 8.8% at pH 7.65. This result showed that when the calcium concentration was low, ammonium addition changed the chemical reaction, moving toward more struvite precipitation in the low pH zone. This analysis was confirmed by the calcium and phosphate distributions figures. The calcium percentages in the precipitate were lower than 15%, under the same condition. And it returned to 35% when the pH was higher than 8.8, meaning increasing pH led to more calcium phosphate and other calcium compounds precipitation (other than struvite). Other calcium compounds could include calcium carbonate, as discussed in Section 5.2.2. The phosphate distribution trend dropped from 30% to 10%, when the pH increased. It is believed that calcium phosphate salts were not the main forms under the high pH condition. Other calcium compounds dominate the reaction in the area. The reason for this could be the low phosphate concentration in the wastewater (35 mg/L, 0.37 mmol/L). The magnesium distribution figure showed the similar trend with ammonium, but with lower percentages. They were less than 5% throughout the whole pH range. However, higher magnesium percentages were observed in the low pH area (<7.8). In addition, when the pH was higher than 8.8, the magnesium percentage in the precipitate was lower than 1%. The calcium to phosphate molar ratios were plotted to study the calcium phosphates formation (Figure 5.7): The Ca/P ratios increased when the pH changed from 1.19 at pH 7.65, to 9.7 at pH 8.9. They remained at 2 from pH 7.8 to 8.8. This result confirmed that in the high pH area, other calcium compounds dominated the chemical reaction. 60 RESULTS AND DISCUSSION 12.00 10.00 i ro o 8.00 E 6.00 O D. "(5 4.00 O 2.00 0.00 7.5 • N/P=3.52 • N/P=9.85 AN/P=18.76 7.8 8.1 pH 8.4 8.7 9.3 Figure 5,7: Ca to PO4 molar ratio vs. pH (Ca=7.6 mmol/L, Second group of jar tests) Medium calcium concentration condition In the medium calcium concentration condition (384 mg/L, 9.6 mmol/L), jar test experiments were conducted with two Ca/Mg molar ratios, 2.15 and 0.93. Results are shown in Fig. 5.8. to 9 . o Q . X 4.00 3.50 3.00 2.50 2.00 1.50 1.00 0.50 0.00 6.3 6.8 7.3 pH 7.8 8.3 8.8 • • Ca/Mg=2.15 • Ca/Mg=0.93 • •M • • • • • • • 9.3 5.00 S? 4.00 I S . O O Q . £2.00 . O . a> 2 1.00 0.00 6.3 • — mm • _ • • • • • • • • • • Ca/Mg=2.15 • Ca/Mg=0.93 6.8 7.3pH 7.8 8.3 8.8 9.3 40.00 35.00 ^ 30.00 |j 25.00 6 20.00 <u Q-15.00 co O 10.00 5.00 6.3 • Ca/Mg=2.15 • Ca/Mg=0.93 6.8 7.3 PH 7.8 8.3 8.8 9.3 50.00 40.00 CD 8 •5.30.00 o 2 5.20.00 o 0- 10.00 0.00 6.3 6.8 7.3 p H 7.8 • Ca/Mg=2.15 • Ca/Mg=0.93 8.3 8.8 9.3 Figure 5.8: NH4, Mg, Ca, P04 to precipitate vs. pH (Ca=9.6 mmol/L, Second group of jar tests) 61 RESULTS AND DISCUSSION Under these conditions, ammonium percentages in precipitate were below 3.6%. However under the condition of more magnesium addition (Ca/Mg=0.93), ammonium distribution showed the trend that more ammonium precipitated out in the low pH, which was similar to the trend in the low calcium condition. This meant that magnesium dosage and low pH helped struvite precipitation, when competing with calcium phosphate precipitation. Calcium and phosphate distributions were more stable, compared to the condition with a low calcium concentration. Between pH 6.7 to 8.7, calcium and phosphate percentage in precipitate remained at 22% and 30%, respectively, meaning that calcium phosphates were the major form of precipitate. Since no experiments had been carried out in the pH higher than 8.8, no conclusions about chemical reaction in this area could be drawn. However, based on the results from the low calcium concentration experiments, it could be suggested that calcium percentages would increase when the pH was raised over 8.8. The reason is that increasing calcium concentration would favor calcium compounds precipitation in the high pH zone, other than struvite precipitation. Magnesium distributions were clearly affected by the Ca/Mg ratio, but still only present in small amount in the precipitates. They were under 2% at a Ca/Mg ratio of 2.15, and 3-4% at a Ca/Mg ratio of 0.93. The potassium percentages were 1.5% or less under both conditions. The calcium to phosphate molar ratio study showed that hydroxyapatite (HAP) was the most likely form of precipitate. The Ca/P ratios were stable at around 1.7, from pH 6.7 to 8.7, slightly more than the stoichiometric demand for hydroxyapatite of 1.67. Other calcium phosphate salts are less than this, (see Figure 5.9) 62 RESULTS AND DISCUSSION 2.50 2.00 (0 o 1.50 E O 1.00 6: O 0.50 0.00 • • • • . • Ca/Mg=2.15 • Ca/Mg=0.93 I 1 1 1 6.3 6.8 7.3 p H 7 . 8 8.3 8.8 9.3 Figure 5.9: Ca to PO4 molar ratio vs. pH (Ca=9.6 mmol/L, Second group of jar tests) High calcium concentration condition Under the high calcium concentration condition (480 mg/L, 12 mmol/L), ammonium addition had no effect on the reaction. The ammonium percentages in the precipitate were less than 0.4%. (Figure 5.10) However, due to the high concentrations of magnesium (250 mg/L, 10.4 mmol/L) and potassium (348 mg/L, 8.94 mmol/L), magnesium potassium phosphate was presented in a small amount (2%) in competing calcium phosphate precipitation. The calcium percentages in the precipitate increased from 20% to 24%, while the phosphate percentage dropped from 35% to 26%, according to the increased pH. These trends confirmed that calcium tended to react with other anions to precipitate out in the higher pH area. 63 RESULTS AND DISCUSSION 2.00 °a)1-60 •5.1 -20 |o.80 10.40 z 0.00 6.3 • N/P=2.0 • N/P=2.54 AN/P=4.3 A 6.8 7 3 p H 7 8 8.3 8.8 9.3 2.50 j£ 2.00 CD •+-* o , „ 150 ' O £ 1.00 Q . J 0.50 0.00 6.3 • N/P=2.0 • N/P=2.54 A N/P=4.3 1 1 1 6.8 7.3 pH 7.8 8.3 8.8 9.3 40.00 35.00 130.00 to 1.25.00 £20.00 g 15.00 10.00 5.00 6.3 • N/P=2.0 • N/P=2.54 AN/P=4.3 6.8 7.3 pH 7.8 8.3 8.8 9.3 40.00 35.00 30.00 •S 25.00 CO CO -*—' CO % 20.00 co 15.00 O C L 10.00 5.00 0.00 6.3 6.8 7.3 p H 7 . 8 • N/P=2.0 • N/P=2.54 AN/P=4.3 8.3 8.8 9.3 Figure 5.10: NFL,, Mg, Ca, PO4 to precipitate vs. pH (Ca=T2 mmol/L, Second group jar test) The calcium to phosphate molar ratios in the experiment under such condition were still in the range of 1.4 to 2.0. (see Figure 5.11) 64 RESULTS AND DISCUSSION 2.50 2.00 1 1.50 2 1 0 0 O 0.50 0.00 • A • W P = 2 . 0 • N / P = 2 5 4 A N / P = 4 . 3 6 . 3 6 . 8 7 . 3 P H 7 . 8 8 . 3 8 . 8 9 . 3 Figure 5.11 Ca to P0 4 molar ratio vs. pH (Ca=12 mmol/L, Second group jar test) Comparison of precipitate recovery and reduction mass from wastewater Table 5.7 shows the mass balance between precipitate recovery and mass reduction from wastewater. Three sets of data are from different calcium concentration conditions 304 mg/L, 384 mg/L and 480 mg/L, respectively. At the low and medium calcium condition, there was a significant discrepancy between recovery and reduction at pH higher than 8. Under the high calcium concentration (480 mg/L, 12 mmol/L), this could be observed throughout the entire experimental pH range. This discrepancy confirmed that high calcium concentration and high pH favor calcium precipitating out with other compounds from greenhouse wastewater, other than phosphate. 65 RESULTS AND DISCUSSION Table 5.7: Comparison of precipitate mass and mass reduction from wastewater (Second group of jar tests) pH Precipitate (mg) A Mass (mg) Ca,P04,NH4,Mg,K, Set 11 7.65 3.4 7.00 Ca=304mg/L(7.6mmol/L) 7.86 13.4 9.62 Ca/Mg=2.84 8.33 25.5 21.2 N/P=3.52 8.61 42.4 28.7 8.88 41.6 40.5 8.94 84.8 63.9 Set 20 6.81 47.3 49.2 Ca=384mg/L (9.6mmol/L) 6.99 107 84.1 Ca/Mg=0.92 7.3 106 114 N/P=3.92 7.65 162 134 8.08 196 162 8.66 191 185 Set 16 6.95 115 59.2 Ca=480mg/L( 12mmol/L) 7.3 152 91.6 Ca/Mg=2.15 7.74 188 183 N/P=4.3 8.01 164 124 8.42 188 127 8.74 198 133 5.3.3 Summary This second group of jar test experiments was conducted with greenhouse wastewater at three calcium concentrations. The calcium concentration was the main factor affecting both the phosphate removal efficiency and chemical precipitation reaction in the wastewater. The jar test confirmed high phosphate removal efficiency. More than 90% of phosphate removal happened with a pH as low as 7.7, depending on the calcium concentration in the water. Under the low calcium concentration condition, ammonium addition changed the chemical reaction at the low pH zone (lower than 8.0). Struvite could be expected in this area. When 66 RESULTS AND DISCUSSION the pH was raised to 8.8, due to the low phosphate concentration, other calcium compounds dominated the precipitation. Under the medium calcium concentration condition, ammonium and magnesium addition help struvite precipitation in the low pH area. Hydroxyapatite (HAP) was still the main product. Under the high calcium concentration condition, ammonium addition showed no effect on the precipitation. Other calcium compounds, other than a phosphate product, could be expected in the high pH area. Battistoni (1998) suggested that struvite formation could be 80 to 100% in competing with hydroxyapatite while Ca/Mg molar ratio was 1.8. However, in this lab experiment, hydroxyapatite was the main precipitate throughout the whole test, struvite or K-struvite had never been the major product. The reason could be the difference of wastewater used. Calcium had been the dominate factor for the jar tests with a large excess amount. Calcium to phosphate molar ratio ranged from 6.31 to 16 (high as 23.1), comparing to average Ca/P ratio of 2.6 in Battistoni's research. In fact, more struvite precipitation occurred in the low calcium concentration condition when calcium to phosphate molar ratio was 3.44. Abbona (1986) also reported that struvite formation occurred when calcium concentration and pH were low in competing with calcium phosphates, the jar tests showed the same results. 67 RESULTS AND DISCUSSION 5.4 Conditional Solubility Product Determination The conditional solubility of product from the precipitation/crystallization process was determined using the procedure stated in Section 4.4. The experiments were carried out with conditions in distilled water at 25°C and 15°C, as well as conditions in greenhouse wastewater at 25°C. The results will be discussed here before the reactor operation analysis, in order to study the reactor operational parameters, such as supersaturation ratios. For one certain crystal, hydroxyapatite or struvite, thermodynamically, the solubility product value (Ksp) should be able to apply to all solutions, if the activity of each chemical can be predicted accurately. However, two reasons limit this to be the possible crystallization process control parameter when applied to the field conditions. Firstly, the solubility product values reported by different authors vary significantly (Section 3.6). Second, under field conditions, all the known and unknown compounds make it impossible to determine the complex activities of these compounds and other possible competing reactions precisely. This is especially true when the product is a mixture; the theoretical solubility product of one kind of crystal is no longer appropriate to serve the purpose of process controlling and monitoring. Therefore, the condition solubility curve from the compounds interested was developed and used to simplify the analysis of reactor operation, for engineering purposes. The compounds included calcium, phosphate, magnesium and potassium, in order to simulate the field greenhouse wastewater condition and the mixture product obtained. This curve was used to determine the saturation of the process. The conditional solubility Ps was calculated from measured calcium, orthophosphate, magnesium and potassium concentrations. Detailed data and calculation for this determination can be found in Appendix E. Figure 5.12 shows the negative logarithm Ps over a pH range from 5.25 to 8.7 for distilled water at 25°C and 15°C, as well as for greenhouse wastewater at 25°C. 68 RESULTS AND DISCUSSION 6.00 7.00 8.00 9.00 10.00 11.00 ST ti 12.00 CL Q . 13.00 14.00 15.00 16.00 17.00 18.00 • Distilled water at 25 degree C • Distilled water at 15 degree C A Greenhouse wastewater at 25 degree C y = -0.2574X2 + 5.212x - 9.4216 y = -0,1747X 2 + 3.6584X - 2.0817 rT = 0.6963 5.5 6.5 pH 7.5 8.5 Figure 5.12: Conditional solubility curve for distilled water at 25°C and 15°C, greenhouse wastewater at 25°C The significant differences between distilled water and greenhouse wastewater was mainly due to the large amount of excess calcium, magnesium and potassium in the greenhouse wastewater even when equilibrium was reached. Other factors like ion strength could increase the crystal solubility. In order to apply to the field condition of reactor operation, the curve from greenhouse wastewater was used to evaluate the saturated conditions of the process. Equation 5.1 described this polynomial curve. pPs = 0.0307pH2 + 0.284pH + 6.421 Eq. 5.1 69 RESULTS AND DISCUSSION 5.5 Reactor Operation The results from the operation of a pilot-scale, fluidized bed reactor are discussed here in terms of phosphate removal efficiency, parameters for controlling phosphate removal, operational problems and the crystal obtained. Since calcium phosphate formation seemed to be the main reaction for this precipitation/crystallization process in greenhouse wastewater, magnesium or ammonium addition were not added for this reactor operation. Only sodium hydroxide solution was injected to adjust the pH value in the reactor. The detailed operational data can be found in Appendix F. The reactor operation can be divided into two sets of runs, based on the different nutrient loadings. The first run was from December 2001 to February 2002. The second run was conducted from the end of March 2002 to May 2002. 5.5.1 Nutrient loading The reactor was set-up and operated from December 2001 to May 2002. As mention in Section 5.1, all the nutrient concentrations of interest changed significantly during this course of study. Figure 5.13 shows this nutrient loading fluctuation. The greenhouse drainage wastewater used for this operation was pumped from the storage tank (Section 4.3.6). During the first period of study, from December 2001 to February 2002, the South Alder Greenhouse operation was at the end of the cropping season. Both volume and nutrient concentrations coming from the pepper field were fairly low and steady. 70 RESULTS AND DISCUSSION 600.00 500.00 o> 400.00 c o 300.00 c CD O o 200.00 O 100.00 • P04-P • Ca A Mg X K • • • X X x A xx X • • xxaocx A ^ A * A A A **** AA4AA4AA)AAAA4^AA m 0.00 15-Nov-01 10-Dec-OI 4-Jan-02 29-Jan-02 23-Feb-02 20-Mar-02 14-Apr-02 9-May-02 3-Jun-02 Date Figure 5.13: Nutrient loading during the reactor operation period The phosphate concentration from the feed stream ranged from 40 to 60 mg/L, while calcium, magnesium and potassium concentrations were on average 305 mg/L, 57 mg/L and 168 mg/L, respectively. The molar ratio of Ca/P was 14.6, exceeding the stoichiometric demand for hydroxyapatite. The Ca/Mg molar ratio was 3.18. Based on the result from first group of jar tests, the chemical reaction for this operation was dominated by the calcium phosphate (hydroxyapatite, HAP) formation. The results from the field reactor operation confirmed this, and will be discussed later in Section 5.5.5. After February 15, 2002, the storage tank was emptied and cleaned for the new cropping season, starting in March. The nutrient concentrations increased dramatically when the reactor was restarted at the end of March 2002. The phosphate ranged from 141 to 219 mg/L. Calcium increased to 522 mg/L. Not only did the increased nutrient loading cause problems for the reactor operation, but also the daily fluctuation. 71 RESULTS AND DISCUSSION 5.5.2 Phosphate removal efficiency One of the main objectives of this study was to test the reactor for phosphate removal from the greenhouse nutrient enriched drainage water. The reactor achieved phosphate removal efficiencies from 30 to 90%, in two different feed strength conditions, when operated at a consistent manner (without serious interrupted like power off, or recycle pump stop). These results show that phosphate removal was a function of operating pH and the influent supersaturation ratio (Figure 5.14 and 5.15). As demonstrated in Section 5.4 for solubility determination, the crystal mixture, mainly calcium phosphates, was highly pH dependent. As with the results from the two groups of jar tests (Section 5.2 and 5.3), the phosphate removal from the reactor running increased when the operating pH was raised. e <D O St a> aj > o E p 100.00 90.00 80.00 70.00 ~ 60.00 50.00 40.00 30.00 £ 20.00 10.00 0.00 7.00 7.50 8.00 8.50 PH 9.00 9.50 Figure 5.14: Phosphate removal efficiency vs. operating pH (reactor run 1) 72 RESULTS AND DISCUSSION However, at a given pH value, different phosphate removal efficiencies were achieved during this reactor operation. They could vary from 30% to 70% at pH 8.0, and 46% to 80% at pH 8.3. Such big differences had not been observed in any of the previous jar test experiments. The reason for this was the different reactor operation conditions. The factors involved included the fluctuating concentrations and the variable flow rates. Supersaturation ratio was then introduced as another monitor parameter for phosphate removal. Supersaturation ratio indicates the saturated condition of the precipitation or crystallization process. Based on the assumption that the effluent supersaturation ratio is unity, (meaning that the equilibrium is reached after the reactor,) influent supersaturation ratio at a given pH indicates the driving force and potential for nutrient removal. Therefore, it can be used to predict the phosphate removal efficiency. As shown in Figure 5.15, phosphate removal efficiency was a function of the influent supersaturation ratio. More than 80% P removal can be found, when the influent SS ratio was higher than 9. 100.00 90.00 80.00 70.00 5 60.00 50.00 40.00 30.00 20.00 10.00 0.00 c <D O i t <D 15 > o E 0.00 • • 4.00 8.00 12.00 Influent S.S.Ratio 16.00 20.00 Figure 5.15: Phosphate removal efficiency vs. influent S.S. ratio (reactor run 1) 73 RESULTS AND DISCUSSION For the second reactor run with a higher nutrient concentration, pH and influent supersaturation ratio also provided precipitation control (Figure 5.16 and 5.17). This second reactor run encountered more problems than the first run. The reactor was operated with less consistent time, due to reasons such as an unexpected power failure. As such, fewer valuable samples were collected. However, the results in terms of phosphate removal efficiencies were demonstrated. As much as 80% phosphate removal could still be achieved at the lower operating pH. Since the significant increase in nutrient concentrations raised the influent supersaturation ratio, it was necessary to lower the operating pH. In the operating pH range of 7.0 to 8.0, this reactor achieved 60-80% of phosphate removal. More than 85% of P removal could be obtained when the pH was increased to more than 8.0. 100.00 90.00 >? 80.00 O e 70.00 a> o 60.00 i t 50.00 "co > 40.00 o E 30.00 £ 20.00 10.00 0.00 • " • • S.50 7.00 7.50 8.00 8.50 9.00 PH Figure 5.16: Phosphate removal efficiency vs. operating pH (reactor run 2) 74 RESULTS AND DISCUSSION The influent supersaturation ratio in this run was much higher than in reactor run 1. By adjusting the operating pH, the reactor removed more than 60% of phosphate, when the influent SS ratio was higher than 30. (see Figure 5.17) 100.00 90.00 80.00 >% O 70.00 c CD 60.00 O SE 50.00 CD 15 40.00 > o 30.00 E CD 20.00 CL 10.00 0.00 0.00 50.00 100.00 150.00 Influent S.S.Ratio 200.00 250.00 Figure 5.17: Phosphate removal efficiency vs. influent SS. ratio (reactor run 2) Overall, the two methods could be used to predict and monitor the phosphate removal for the reactor operation, however, they were interdependent and required to be considered together, for more accurate control. When conditions were known and under control, pH adjustment was still the simplest method for daily operation of the reactor. It only takes into account one factor and can be easily achieved. 75 RESULTS AND DISCUSSION 5.5.3 Supersaturation ratio The influent, in-reactor and effluent supersaturation ratio for the two reactor runs are shown in Figures 5.18 and 5.19. For the first reactor run, the influent supersaturation ratio ranged from 4 to 19. After controlled dilution from the recycle effluent stream, the in-reactor supersaturation ratio was maintained at around 3. From January 2001, the effluent supersaturation ratios were close to 1, meaning the reaction approached completion and equilibrium was established. It should be noted that the pH measurement error could cause big differences in supersaturation ratio numbers. An error of 0.1 in the pH reading leads to a change of over 0.3 in the SS ratio. Due to the reactor encrustation during the course of this operation, the pH probe inside the reactor needed to be cleaned and calibrated frequently, as such, pH reading could be expected. 20.00 18.00 16.00 14.00 •B 12.00 co or 10.00 CO CO • Influent S.S.Ratio • In-Reactor S.S.Ratio • Effluent S.S.Ratio • • 8.00 6.00 4.00 2.00 0.00 20-Nov-01 5-Dec-01 20-Dec-01 4-Jan-02 19-Jan-02 3-Feb-02 18-Feb-02 Date Figure 5.18: Supersaturation ratios during the operation period (run 1) A A A A A A X J I A A ^ A A A I 76 RESULTS AND DISCUSSION Since the influent strength was far stronger than expected and fluctuated in the second run, in-reactor supersatuation ratios fluctuated from 6 to 15 accordingly. Also the sample analysis showed that effluent SS ratios have not been able to reach unity. However, given this condition, the reactor could still achieve more than 60% phosphate removal (Section 5.5.2). 250.00 200.00 co rr co co 150.00 100.00 50.00 0.00 • Influent S.S. Ratio • In-Reactor S.S. Ratio A Effluent S.S.Ratio • • 1 * I I - i i XI i * I i i 20-Mar-02 4-Apr-02 19-Apr-02 4-May-02 19-May-02 3-Jun-02 Date Figure 5.19: Supersaturation ratios during the operation period (run 2) 5.5.4 Flow rates Figure 5.20 and 5.21 shows different flow rates during the reactor operation. This was investigated for the purpose of keeping the small crystals in the reactor while maintaining enough up-flow velocity. It is generally believed that turbulence is important in the crystallization process. Solubility chemistry plays a dominated role in the nucleation phase, while mixing is the major factor for the crystal growth phase. However there is no such quantification standard for a fluidized bed reactor. Therefore, the concept of Reynolds Number was adopted as a guideline for this study. The detailed calculation of fluid Reynolds Numbers, under different flow rates, can be 77 RESULTS AND DISCUSSION found in Appendix B. These numbers were based on the condition of no crystals inside the reactor. Once the reactor was filled with crystals, the Reynolds Number changed. One of the main problems encountered in the reactor operation was the powder like nature of the product mixture, even when reactor was seeded with various sizes particles. Different flow rates of 3500 mL/min, 2500 mL/min and 1500 mL/min were applied. Most of the crystals were either soft or in powder form, meaning that the harvesting would be difficult. This situation existed in the second and third reaction zones in the reactor, when the flow rate was low at 1500 mL/min. As can be seen in the figures, flow rates fluctuated even when was they were carefully readjusted, after daily maintenance. There were reasons for this and will be discussed in a later section. 30CX) c 2500 'E . ^ 2000 a> 2 1500 | * 1000 co •»-» o t- 500 • • • • • • • • • • • 0 4 , , , , , 1 20-Nov-01 5-Dec-01 20-Dec-01 4-Jan-02 19-Jan-02 3-Feb-02 18-Feb-02 Date Figure 5.20: Total flow rates during the study period (run 1) 78 RESULTS AND DISCUSSION c 'E E 3 "to 5000 4500 4000 3500 3000 E 2500 5 o 2000 m 1500 1000 500 20-Mar-02 4-Apr-02 19-Apr-02 4-May-02 19-May-02 3-Jun-02 Date Figure 5.21: Total flow rates during the study period (run 2) 5.5.5 Crystals obtained A small amount of crystals had been harvested from two reactor runs. They grew on the surface of the seeding material. In order to avoid complexity, precipitate from the reactor operation was used as seeding materials back to the reactor. Hydroxyapatite was the main product of this precipitate. Most of the solid products from the reactor operation were either soft or in powder form. They accumulated in the volume of about 0.22 L in the second and third section of the reactor, but could not be harvested. However, the crystals obtained were dissolved in acid solution and analyzed for chemical composition. They were also examined under an optical microscope (Figure 5.22). 79 RESULTS AND DISCUSSION Figure 5.22: Crystals from reactor operation (run 1) The crystals obtained from the first reactor run were 1-2 mm in diameter. In order to determine the chemical composition, three crystal samples were analyzed (Table 5.8). The crystal composition was similar to those of the previous jar test precipitates. 8 0 RESULTS AND DISCUSSION Table 5.8: Average results of crystal composition analysis (run 1) Compositions by Mass % Standard Deviation Calcium 26.21 1.3 Phosphate 35:48 2.8 Magnesium 1.32 0.1 Potassium 0.13 0.04 The crystals obtained from the second period reactor run were of different shape from that of the first run. They formed solid shells on the surface of seeding materials. It is suggested that this was due to the intense collisions between the crystals, when the reactor was operated with high up-flow velocities in April 2002. When dried, the shells separated from the seeds (Figure 5.23). Their composition was also determined (Table 5.9). The results showed no major differences from the crystals from run number one. Table 5.9: Average results of crystal composition analysis (run 2) Compositions by Mass Standard Deviation % Calcium 28.15 2.0 Phosphate 33,39 2.6 Magnesium 1.59 0.15 Potassium 0.25 0.1 DHV Crystallactor obtained HAP crystal growing on the surface of the sand seed. The crystal harvested from this reactor operation formed with the same way, on the surface of seeding material. 81 RESULTS AND DISCUSSION Figure 5.23: Crystals from reactor operation (run 2) 82 RESULTS AND DISCUSSION 5.5.6 Operational problems The reactor operation from December 2001 to May 2002 encountered more problems than expected, including several major power failures. Other major problems, such as complete injection port plugging, made operation difficult. Dairy maintenance The reactor was set up in the greenhouse in South Delta, BC, which is more than 45 minutes driving from UBC campus. Reactor maintenance could only be carried out two or three times a week. Since the process control was critical, any unexpected problem could cause a loss of weeks' effort. Power failure happened once in January 2002, and three other times, on April 3, 19 and 22, respectively. The recycle pump stopped once, on May 9. Feed strength fluctuation As mention in Section 5.5.1, the feed concentrations varied significantly during the operation period. The phosphate concentration for the second run was almost three times the one used for the first run. This basically changed the feed to another type of wastewater, for the crystallization process. Even worse, the fluctuation happened daily between reactor maintenance (every 2-3 days). The reality was facing a new operating condition without warning, this makes it extremely difficult to control the reactor operation in a consistent manner. Injection port plugging Another major problem encountered in the reactor operation was the severe injection plugging. It happened from the beginning. The caustic injection port plugged completely, causing a loss in control of pH and other conditions. Caustic (sodium hydroxide) solution was diluted, but the problem was still pronounced. Another modification included using the MasterFlex peristaltic pump to provide a constant caustic flow to the reactor. The pH control 83 RESULTS AND DISCUSSION pump was also used, but it just injected a small amount of caustic for the rest of the pH control needed. After this modification, the pH was controlled in the range of +0.3 values. The injection port plugging problem was mainly due to the high degree of supersatuation ratio in this section, possibly resulting in the spontaneous nucleation in this small area. The pH control pump working method could be the other main reason contributing to this plugging. It injects the caustic solution intermittently and tends to suck back right after injection. That is why the plugging always occurred at the injection port, rather than in the whole section, and stopped the flow. The MasterFlex pump works in a continuous flow manner and no severe plugging was observed at this pump injection port. Given such a high feed strength, a continuous flow to provide a caustic solution is definitely recommended. Other methods, like reducing the operating pH and increasing the recycle flow to decrease the supersatuation ratio, were also suggested, in dealing with the plugging. In addition, modifying the configuration of the injection port could help prevent this problem. Flow rates variation The variation of progressive cavity pump speeds also caused some problems. Both the feed pump and the recycle pump controllers performed with poor accuracy, even when adjustments were made at each maintenance day. The variation in the flow rate could be up to 30% some days. This is shown in Figures 5.20 and 5.21. The pump head in the greenhouse wastewater storage tank remained very consistent, so this was not the reason for the flow rate change. The plugging problem might have an effect on this variation. However, more accurate controllers and frequent adjustments could solve this problem. In this operation, maintenance could only had been carried out two or three times a week. 84 RESULTS AND DISCUSSION Reactor fouling and algae growth Encrustation and algae growth were observed inside the reactor and in both the top section and external clarifiers walls, even when the reactor was operated at high upflow rates. This caused the clear piping used for the reactor, to become coated with an opaque layer, thus preventing good observation. More powder-like crystals accumulated on the interior walls of reactor, while more algae were found growing on the walls of the top section and external clarifiers. Cleaning of these walls was periodically required. 5.5.7 Summary The reactor operated with two different feed-strength greenhouse wastewaters from December 2001 to May 2002. The results confirmed that precipitation/crystallization process was an effective way to removal phosphate from enriched greenhouse drainage wastewater. Phosphate removal efficiencies were in the range of 30% to 92% under various conditions for both feed strengths (phosphate of 50 mg/L and 200 mg/L). The operating pH and influent supersaturation ratio were the two controlling parameters for this process. They need to be considered together if accurate prediction of removal was required. Under the low nutrient concentration condition, the operating pH was higher in order to achieve higher phosphate removal. Under the high concentration condition, a lower operating pH achieved the same removal efficiency, because the influent supersaturation ratio was high. Recycling the effluent stream back to the reactor was a useful method to reduce the strength of feed flow. Thus, it can control the in-reactor supersaturation ratio, which is the key factor for the crystallization process. 85 RESULTS AND DISCUSSION Most of crystals were either soft or in powder form. They accumulated in the second and third sections of the reactor, but could not be harvested. Those that were harvested were growing on the surface of the seeding material. The crystals obtained were of the same chemical composition as the precipitate from the jar tests. They were mainly calcium phosphate (hydroxyapatite, HAP), together with a small amount of K-Struvite and other compounds. 86 CONCLUSIONS CHAPTER 6 CONCLUSIONS Based on the results from the two groups of jar tests and the pilot-scale reactor operation in the field with greenhouse wastewater, the following conclusions are drawn. • Greenhouse drainage wastewater contains very high concentrations of phosphate, calcium, magnesium, and potassium, and these concentration vary from time to time, depending on the greenhouse operation period. Low nutrient concentrations (phosphate of 50 mg/L) could be found at the end of cropping season in winter, while high concentrations (phosphate of 200 mg/L) occur during the growing season, before summer. • The phosphate precipitation/crystallization process is an efficient way to remove phosphate from the greenhouse wastewater. More than 90% of the phosphate could be removed from the greenhouse wastewater. The end product of this process is a mixture, hydroxyapatite (HAP), Ca5(P04)30H was the main product. • Phosphate removal was also affected by an addition of magnesium. It decreased the phosphate removal rates. • At a given Ca/Mg ratio, the chemical content of precipitates, in terms of calcium, magnesium and phosphate, were not affected by the operating pH. The content of the precipitates was affected by the Ca/Mg ratio. A higher calcium content in the precipitate was obtained in the wastewaters with high Ca/Mg ratio. 87 CONCLUSIONS • An addition of magnesium did not affect the potassium content in the precipitates. K-struvite was not a major product in the precipitate, even with the addition of a large quantity of magnesium. • A jar test experiment was conducted with greenhouse wastewater using three calcium concentration conditions. The calcium concentration was the main factor affecting both phosphate removal efficiency and chemical precipitation in the wastewater. • High phosphate removal efficiencies were achieved when magnesium and ammonium addition were added. More than 90% of phosphate removal happened with a pH as low as 7.7, depending on the calcium concentration in the water. • In the low calcium concentration condition (calcium of 308 mg/L), ammonium addition changed the chemical reaction in the low pH zone (lower than 8.0). Struvite could be expected to occur. When the pH was raised to 8.8, due to the low phosphate concentration, other unidentified calcium compounds dominated the precipitation process. • In the medium calcium concentration condition (calcium of 384 mg/L), ammonium and magnesium addition help struvite precipitation in the low pH area. Hydroxyapatite (HAP) was still the main product. • In the high calcium concentration condition (calcium of 480 mg/L), ammonium addition showed no effect on the precipitation. Calcium compounds^  other than the phosphate product, could be expected in the high pH range. 88 CONCLUSIONS • The pilot-scale reactor was operated with two different feed-strength greenhouse wastewaters (phosphate of 50 mg/L and 200 mg/L) from December 2001 to May 2002. The results confirmed that precipitation/crystallization process was an effective way to remove phosphate from enriched greenhouse drainage wastewater. Phosphate removal efficiencies were in the range of 30% to 92% under various conditions in both feed strengths. • Operating pH and influent supersaturation ratio were the two controlling parameters for reactor operation. They need to be considered together for accurate prediction of removal. In the low nutrient concentration condition, operating pH was higher in order to achieve higher phosphate removal. In the high concentration condition, a lower operating pH could obtain the same removal efficiency, since the influent supersaturation ratio was high. • Recycling the effluent stream back to the reactor was a useful method to reduce the strength of feed flow. Thus, it can control the in-reactor supersaturation ratio, which is the key factor for crystallization process. • Most of crystals from the reactor operation were either soft or in powder form. They accumulated in the second and third sections of the reactor but could not be harvested. Those that were harvested were growing on the surface of the seeding material. • The crystals obtained were of the same chemical composition as the precipitate from the jar test. They were mainly calcium phosphate (hydroxyapatite, HAP), together with a small amount of K-Struvite and other undefined compounds. 89 RECOMMENDATIONS CHAPTER 7 RECOMMENDATIONS Based on the knowledge and experience gained from this study on lab jar test and pilot-scale reactor operation, the following recommendations are made. • For the lab experiment, further investigation could help identified and quantities other compounds of the product mixture, besides calcium phosphates. • Based on the results from the second group of jar tests, struvite could be obtained from the greenhouse wastewater with the presence of ammonium under certain conditions. This might provide an opportunity to obtain a more valuable product. A cheap ammonium source, like animal manure wastewater, could be used for the source of nitrogen. • For the field reactor operation, a better understanding and prediction of the feed strength fluctuation would lead to a better operation. On-site measurement of phosphate concentration was recommended. • Longer consistent reactor runs and other optimizations (such as lower in-reactor SS ratio) could be tried, to obtained crystals in a better shape for easy harvest and application. • Further study of the supersaturation ratio, as the major controlling parameter, would be useful for better reactor operation. • More frequent maintenance of the reactor operation is recommended, if possible. It would avoid many difficulties and problems encountered in the course of this study. 90 RECOMMENDATIONS • Other pH adjusting methods could be applied to lower the cost of expensive sodium hydroxide used. Calcium hydroxide solution can be used if hydroxyapatite is still the targeted product. Air stripping could be another way to raise the operating pH without increasing the chemical cost, but a reactor design with appropriate evaluation is needed for this. • Reactor design modifications were also recommended at the injection port section. If other additions like magnesium or ammonium need to be added, caustic and other solute injections could be separated, to avoid the plugging problems caused by a high, over saturated conditions in the injection region of the reactor. • The reactor worked better with continuous caustic injection by the MasterFlex pump. The operating pH control can be achieved by using both the MasterFlex pump and pH controller. It prevented complete plugging at the caustic injection port. 91 REFERENCES REFERENCES Abbona F., M. H. Lundager and R. Boistelle (1982) Crystallization of two magnesium phosphates, struvite and newberyite: Effects of pH and concentration. Journal of Crystal Growth, Vol. 57, No. 6, pp. 6-14. Abbona, F. and H.L. 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Yamasita and Y. Nawamura (2000). Phosphorus removal from sidestreams by crystallization of magnesium-ammonium-phosphate using seawater. Water and Environmental Management. Vol. 14, No. 4, pp. 291-296. Munch, E. and K. Barr (2001) Controlled struvite crystallization for removing phosphorus from anaerobic digester sidestreams. Water Research, Vol. 35, No. 1, pp. 151-159. Nancollas, G.H. (1984). Phosphate Minerals. Springer-Verlag, London. Seckler, M.M., O.S.L Bruinsma and G.M Van Rosmalen (1996) Calcium phosphate precipitation in a fluidized bed in relation to process conditions: a black box approach. Water Research, Vol. 30, pp. 1677-1685. Snoeyink V. and D. Jenkins (1980) Water Chemistry. John Wiley & Sons, New York. Stumm W. and J. Morgan (1981) Aquatic Chemistry. Wiley-Interscience, New York. Taylor, A.W., A.W. Frazier and E.L. Gurney (1963) Solubility products of magnesium ammonium and magnesium potassium phosphates. Journal of the Chemical Society, pp. 1580-1584. Ueno, Y and M. Fujii (2001). Three years experience of operating and selling recovered struvite from full-scale plant. Environmental Technology, Vol. 22, No. 11, pp. 1373-1381. Valsami-Jones, E. (2001) Calcium phosphate precipitation. Scope Newsletter. Vol. 41, pp. 8-15. Valsami-Jones, E., K.V. Ragnarsdottir, A. Putnis, D. Bosbach, A.J. Kemp and G. Cressey (1998) The dissolution of apatite in the presence of aqueous metal cations at pH 2-7. Chemical Geology, Vol. 151, pp. 215-233. Webb K. and G. Ho (1992) Struvite solubility and its application to a piggery effluent problem. Water Science and Technology, Vol. 26, No. 9-11, pp. 2229-2232. Woods, N.C., S.M. Sock and G.T. Daigger (1999). Phosphorus recovery technology modeling and feasibility evaluation for municipal wastewater treatment plants. Environmental Technology. Vol. 20, No, 7, pp. 663-680. Yu, J. (2001). Phosphorus inventory in British Columbia. MEng Report, Department of Civil Engineering, University of British Columbia, Canada. 94 REFERENCES Zawacki S.J., J.C. Heughebaert and G.H. Nancollas (1990) The growth of nonstoichiometric apatite from aqueous solutions at 37°C. II. Effects of pH upon the precipitated phase. Journal of Colloid and Interface Science, Vol. 135, pp 33-44. 95 APPENDIX A APPENDIX A CALCULATIONS FOR UPFLOW VELOCITIES IN REACTOR UpflowVelocity = Flowrate CrossSectionArea Table B-l Reactor section Diameter Cross section area (Flowrate=3.5L/min) Upflow velocity (Flowrate=2.5L/min) (Flowrate= 1.5L/min) cm cm cm/min m/s cm/min m/s cm/min m/s First 4 12.6 277.8 0.046 198.4 0.033 119.0 0.020 Second 5.2 21.2 165.1 0.028 117.9 0.020 70.8 0.012 Third 7.7 46.6 75.1 0.013 53.6 0.009 32.2 0.005 Top clarifier 20.5 330.1 10.6 0.002 7.6 0.001 4.5 0.001 96 APPENDIX B APPENDIX B CALCULATIONS FOR FLUID REYNOLDS NUMBERS IN REACTOR VDp where N R = Reynolds number, dimensionless V = average velocity of the fluid, m/sec. D = diameter of pipe, m p = density of fluid, kg/m3 u. = viscosity of the fluid, N.s/m 2 Table C-l Temperature (°C) P (kg/m3) nx 103 (N.s/m2) 15 999.1 1.139 25 997.0 0.890 Table C-2: Reynolds number when flow rate at 3.5 L/min Reactor section Diameter Upflow velocity Reynolds number cm m/s 15 °C 25 °C First section 4 0.046 1624 2074 Second section 5.2 0.028 1255 1603 Third section 7.7 0.013 845 1080 Top clarifier 20.5 0.002 318 406 97 APPENDIX B Table C-3: Reynolds number when flow rate at 2.5 L/min Reactor section Diameter Upflow velocity Reynolds number cm m/s 15 °C 25 °C First section 4 0.033 1160 1482 Second section 5.2 0.020 896 1145 Third section 7.7 0.009 604 771 Top clarifier 20.5 0.001 227 290 Table C-4: Reynolds number when flow rate at 1.5 L/min Reactor section Diameter Upflow velocity Reynolds number cm m/s 15 °C 25 °C First section 4 0.020 696 889 Second section 5.2 0.012 538 687 Third section 7.7 0.005 362 463 Top clarifier 20.5 0.001 136 174 98 APPENDIX C APPENDIX C DATA FOR FIRST GROUP OF JAR TEST 99 APPENDIX C Data from LaChat PH mg-P/L Set 1 7.5 8.727 7.664 8 3.493 3.084 8.5 1.579 1.423 8.5 1.2 0.992 9 0.8 0.624 9.5 0.483 0.466 Set 2 7.5 11.023 9.685 8 5.286 3.561 8.5 1.427 1.279 8.5* 1.55 1.313 9 0.5 0.546 9.5 0.493 0.473 Set 3 7.5 11.026 7.788 8 5.506 4.433 8.3 2.5 1.976 8.7 1.2 0.999 9 0.611 0.566 Average P removal mg-P/L mg-P04/L Efficiency % 8.20 25.12 61.20 3.29 10.08 84.43 1.50 4.60 92.89 1.10 3.36 94.81 0.71 2.18 96.63 0.47 1.45 97.75 10.35 31.73 50.98 4.42 13.56 79.06 1.35 4.15 93.59 1.43 4.39 93.22 0.52 1.60 97.52 0.48 1.48 97.71 9.41 28.83 55.46 4.97 15.23 76.47 2.24 6.86 89.40 1.10 3.37 94.79 0.59 1.80 97.21 Data from ICP mg-Mg/L mg-K/L mg-Ca/L 72.44 190.2 399.9 72.8 191.3 393.9 70.93 188.7 383.4 69.08 182.4 367.1 71.66 189.1 381 70.69 186.1 372.3 76.27 193.6 419.5 75.52 191 399.6 75.17 192.8 389.1 73.48 196.4 392.7 74.43 191.4 385.7 74.71 189.6 381.2 77.22 185.7 397 76.06 184.2 379.6 75.38 179.8 373.9 73.49 177.5 368.5 75.19 184.8 371.1 gw 22 20.243 21.12 64.73 76.24 200.10 454.40 gw+MgCI2 21.878 19.191 20.53 62.93 78.76 187.9 428.7 MgCI2 123.08 Precipitate solution Set 1 7.5 12.834 10.603 11.72 35.91 1.287 0.8951 27.94 8 14.665 12.165 13.42 41.11 1.696 1.364 35.54 8.5 16 13.241 14.62 44.80 1.692 1.243 38.38 8.5 18 17.002 17.50 53.63 2.453 2.099 51.36 9 14.041 11.612 12.83 39.31 1.8 1.428 38.73 9.5 15.249 13.116 14.18 43.46 2.254 2.182 45.96 Set 2 7.5 10.5 8.969 9.73 29.83 1.225 0.964 25.68 8 10.348 8.927 9.64 29.53 1.262 1 26.66 8.5 21.321 17.044 19.18 58.79 2.3 1.851 50.08 8.5 11.265 9.239 10.25 31.42 1.354 1.042 29.06 9 8.201 6.569 7.39 22.63 0.9608 0.5369 19.66 9.5 17.847 13.71 15.78 48.35 2.457 2.384 49.12 Set 3 7.5 14.16 10.927 12.54 38.44 1.463 0.1723 32.01 8 13.898 11.95 12.92 39.61 1.575 0 35.09 8.3 27.365 23.706 25.54 78.25 3.374 2,257 72.52 8.7 5.011 4.31 4.66 14.28 0.5804 0.7583 13.67 9 12.735 11.063 11.90 36.46 1.601 0.8114 35.09 100 APPENDIX C molor ratio ? H i mmoV mrnol/L mmol/L C a / M 9 C a / P ° 4 M 9 / P ° 4 ^ Set 1 7.5 0.26 3.02 4.88 10.00 8 0.11 3.03 4.91 9.85 8.5 0.05 2.96 4.84 9.59 8.5 0.04 2.88 4.68 9.18 9 0.02 2.99 4.85 9.53 9.5 0.02 2.95 4.77 9.31 Set 2 7.5 0.33 3.18 4.96 10.49 8 0.14 3.15 4.90 9.99 8.5 0.04 3.13 4.94 . 9.73 8.5* 0.05 3.06 5.04 9.82 9 0.02 3.10 4.91 9.64 9.5 0.02 3.11 4.86 9.53 Set 3 7.5 0.30 3.22 4.76 9.93 8 0.16 3.17 4.72 9.49 8.3 0.07 3.14 4.61 9.35 8.7 0.04 3.06 4.55 9.21 9 0.02 3.13 4.74 9.28 gw 0.68 3.18 5.13 11.36 3.58 16.67 4.66 7.53 v+MgCI2 0.66 3.28 4.82 10.72 3.27 16.18 4.95 7.27 MgCI2 'recipitate solution Set1 7.5 0.38 0.05 0.02 0.70 13.03 1.85 0.14 0.06 8 0.43 0.07 0.03 0.89 12.57 2.05 0.16 0.08 8.5 0.47 0.07 0.03 0.96 13.61 2.03 0.15 0.07 8.5 0.56 0.10 0.05 1.28 12.56 2.27 0.18 0.10 9 0.41 0.08 0.04 0.97 12.91 2.34 0.18 0.09 9.5 0.46 0.09 0.06 1.15 12.23 2.51 0.21 0.12 Set 2 7.5 0.31 0.05 0.02 0.64 12.58 2.04 0.16 0.08 8 0.31 0.05 0.03 0.67 12.68 2.14 0.17 0.08 8.5 0.62 0.10 0.05 1.25 13.06 2.02 0.15 0.08 8.5 0.33 0.06 0.03 0.73 12.88 2.20 0.17 0.08 9 0.24 0.04 0.01 0.49 12.28 2.06 0.17 0.06 9.5 0.51 0.10 0.06 1.23 12.00 2.41 0.20 0.12 Set 3 7.5 0.40 0.06 0.00 0.80 13.13 1.98 0.15 0.01 8 0.42 0.07 0.00 0.88 13.37 2.10 0.16 0.00 8.3 0.82 0.14 0.06 1.81 12.90 2.20 0.17 0.07 8.7 0.15 0.02 0.02 0.34 14.13 2.27 0.16 0.13 9 0.38 0.07 0.02 0.88 13.15 2.29 0.17 0.05 APPENDIX C Data from LaChat P removal Data from ICP pH mg-P/L mg-P04/L Efficiency % mg-Mg/L mg-K/L mg-Ca/L Set 4 7.75 8.321 25.50 68.03 80.6 172.8 402.8 7.96 5.473 16.77 78.97 79.36 171.7 393.8 8.09 3.542 10.85 86.39 77.25 162.4 380 8.38 2.222 6.81 91.46 78.7 168.4 388.6 8.88 0.749 2.30 97.12 78.56 169 378.9 9.35 0.372 1.14 98.57 77.68 168.2 369.5 gw 29.287 89.75 80.62 173.60 433.60 Set5 7.63 15.556 47.67 40.23 141.4 183.4 411.1 7.91 6.794 20.82 73.90 135.9 179.5 387.6 8.01 5.238 16.05 79.87 137.7 184.6 391.5 8.29 2.443 7.49 90.61 135.3 180.2 373.9 8.65 1.224 3.75 95.30 129.3 181.3 345 8.9 0.523 1.60 97.99 129.7 178.1 327.1 gw 30.532 93.57 86.64 187.20 453.40 gw+MgCI2 26.373 80.82 142.10 183 436.6 Set 6 7.54 13.081 40.09 49.74 192.9 182.4 407 7.73 8.553 26.21 67.14 192.5 181.2 397.7 8.07 5.06 15.51 80.56 191.8 178.9 390.1 8.31 2.993 9.17 88.50 191.6 182.3 391.3 8.76 1.035 3.17 96.02 189.2 178.8 379.4 9.18 0.447 1.37 98.28 186.1 180.1 374.8 gw 22.132 67.82 83.16 175.50 440.00 gw+MgCI2 21.81 66.84 193.70 179.5 427.6 Precipitate solution Set 4 7.75 37.692 115.51 3.885 3.164 75.63 7.96 43.384 132.95 6.426 6.392 121.3 8.09 45.84 140.48 6.465 6.457 123.8 8.38 74.57 228.52 8.064 7.639 161.9 8.88 57.098 174.98 7.995 7.585 165.2 9.35 67.822 207.84 9.225 9.306 197.5 Set 5 7.63 7.42 22.74 1.239 0.05 17.94 7.91 30.91 94.72 4.191 1.152 73.36 8.01 36.904 113.09 5.569 1.832 96.59 8.29 51.812 158.78 9.812 4.169 191 8.65 54.792 167.91 9.127 3.746 161.2 8.9 74.462 228.19 14.09 7.233 289.6 Set 6 7.54 15.994 49.01 3.648 0.8974 33.41 7.73 30.106 92.26 7.829 3.008 69.92 8.07 27.596 84.57 7.651 2.562 70.2 8.31 39.178 120.06 11.31 4.068 106.2 8.76 26.526 81.29 7.611 2.48 76.35 9.18 73.31 224.66 17.86 7.357 173.9 102 APPENDIX C pH Mg mmol/L K mmol/L Ca mmo Set 4 7.75 3.36 4.43 10.07 7.96 3.31 4.40 9.85 8.09 3.22 4.16 9.50 8.38 3.28 4.32 9.72 8.88 3.27 4.33 9.47 9.35 3.24 4.31 9.24 gw 3.36 4.45 10.84 Set 5 7.63 5.89 4.70 10.28 7.91 5.66 4.60 9.69 8.01 5.74 4.73 9.79 8.29 5.64 4.62 9.35 8.65 5.39 4.65 8.63 8.9 5.40 4.57 8.18 gw 3.61 4.80 11.34 gw+MgCI2 5.92 4.69 10.92 Set 6 7.54 8.04 4.68 10.18 7.73 8.02 4.65 9.94 8.07 7.99 4.59 9.75 8.31 7.98 4.67 9.78 8.76 7.88 4.58 9.49 9.18 7.75 4.62 9.37 gw 3.47 4.50 11.00 gw+MgCI2 8.07 4.60 10.69 Precipitate solution Set 4 7.75 0.16 0.08 1.89 7.96 0.27 0.16 3.03 8.09 0.27 0.17 3.10 8.38 0.34 0.20 4.05 8.88 0.33 0.19 4.13 9.35 0.38 0.24 4.94 Set 5 7.63 0.05 0.00 0.45 7.91 0.17 0.03 1.83 8.01 0.23 0.05 2.41 8.29 0.41 0.11 4.78 8.65 0.38 0.10 4.03 8.9 0.59 0.19 7.24 Set 6 7.54 0.15 0.02 0.84 7.73 0.33 0.08 1.75 8.07 0.32 0.07 1.76 8.31 0.47 0.10 2.66 8.76 0.32 0.06 1.91 9.18 0.74 0.19 4.35 molor ratio Ca/Mg Ca/PQ4 Mg/PQ4 K/P04 3.23 11.47 3.56 4.71 3.14 11.51 3.67 4.87 1.84 12.83 6.96 5.52 3.17 15.41 4.85 6.30 1.32 15.19 11.47 6.54 11.68 1.56 0.13 0.07 11.33 2.17 0.19 0.12 11.49 2.09 0.18 0.11 12.05 1.68 0.14 0.08 12.40 2.24 0.18 0.11 12.85 2.26 0.18 0.11 8.69 1.87 0.22 0.01 10.50 1.84 0.18 0.03 10.41 2.03 0.19 0.04 11.68 2.86 0.24 0.06 10.60 2.28 0.22 0.05 12.33 3.01 0.24 0.08 5.50 1.62 0.29 0.04 5.36 1.80 0.34 0.08 5.51 1.97 0.36 0.07 5.63 2.10 0.37 0.08 6.02 2.23 0.37 0.07 5.84 1.84 0.31 0.08 103 APPENDIX C Data from LaChat P removal Data from ICP PH mg-P/L mg-P04/L Efficiency % mg-Mg/L mg-K/L mg-Ca/L Set 7 7.5 15.151 46.43 28.52 225.5 163.1 434.5 7.8 11.347 34.77 46.47 225.6 161.9 428.9 8 7.931 24.30 62.59 229.5 161.1 426 8.3 4.432 13.58 79.09 229.9 159.1 408.4 8.7 1.63 5.00 92.31 224.9 161.5 408.9 9 0.773 2.37 96.35 226 161.2 404.9 gw 18.167 55.67 88.91 161.60 471.30 gw+MgCI2 22.354 68.50 223.40 164 462.2 Set 8 7.5 16.611 50.90 21.64 366.9 166.5 435.2 7.8 9.645 29.56 54.50 363.4 164 422.8 8 9.847 30.18 53.55 362.8 164.3 423 8.3 4.969 15.23 76.56 362.6 165.5 411.9 8.7 1.688 5.17 92.04 355.8 163.5 402.1 9 0.929 2.85 95.62 358 162.7 400.3 gw 21.146 64.80 88.38 160.70 471.70 gw+MgCI2 20.634 63.23 362.90 164.5 438.9 Precipitate solution Set 7 7.5 15.04 46.09 5.696 1.684 44.14 7.8 44.54 136.49 9.498 2.786 76.82 8 38.944 119.34 11.66 3.467 93.46 8.3 64.47 197.57 17.42 4.783 136.2 8.7 66.666 204.30 18.69 4.823 157.5 9 68.372 209.53 20.47 6.719 170 Set 8 7.5 7.444 22.81 3.038 0 15.67 7.8 29.88 91.57 9.86 1.073 55.53 8 34.162 104.69 12 1.375 67.49 8.3 52.95 162.27 21.8 3.556 118.5 8.7 60.64 185.83 22.56 3.143 137.3 9 57.406 175.92 25.21 3.779 144.1 104 APPENDIX C molor ratio pH P04 mmol/L Mg mmol/L K mmol/L Ca mmol/L Ca/Mg Ca/P04 Mg/P04 K/P04 Set 7 7.5 0.49 9.40 4.18 10.86 7.8 0.37 9.40 4.15 10.72 8 0.26 9.56 4.13 10.65 8.3 0.14 9.58 4.08 10.21 8.7 0.05 9.37 4.14 10.22 9 0.02 9.42 4.13 10.12 gw 0.59 3.70 4.14 11.78 3.18 20.11 6.32 7.07 gw+MgCI2 0.72 9.31 4.21 11.56 1.24 16.02 12.91 5.83 Set 8 7.5 0.54 15.29 4.27 10.88 7.8 0.31 15.14 4.21 10.57 8 0.32 15.12 4.21 10.58 8.3 0.16 15.11 4.24 10.30 8.7 0.05 14.83 4.19 10.05 9 0.03 14.92 4.17 10.01 gw 0.68 3.68 4.12 11.79 3.20 17.29 5.40 6.04 gw+MgCI2 0.67 15.12 4.22 10.97 0.73 16.48 22.72 6.34 Precipitate solution Set 7 7.5 0.49 0.24 0.04 1.10 4.65 2.27 0.49 0.09 7.8 1.44 0.40 0.07 1.92 4.85 1.34 0.28 0.05 8 1.26 0.49 0.09 2.34 4.81 1.86 0.39 0.07 8.3 2.08 0.73 0.12 3.41 4.69 1.64 0.35 0.06 8.7 2.15 0.78 0.12 3.94 5.06 1.83 0.36 0.06 9 2.21 0.85 0.17 4.25 4.98 1.93 0.39 0.08 Set 8 7.5 0.24 0.13 0.00 0.39 3.09 1.63 0.53 0.00 7.8 0.96 0.41 0.03 1.39 3.38 1.44 0.43 0.03 8 1.10 0.50 0.04 1.69 3.37 1.53 0.45 0.03 8.3 1.71 0.91 0.09 2.96 3.26 1.73 0.53 0.05 8.7 1.96 0.94 0.08 3.43 3.65 1.75 0.48 0.04 9 1.85 1.05 0.10 3.60 3.43 1.95 0.57 0.05 105 APPENDIX C Data from LaChat P removal pH mg-P/L mg-P04/L Efficiency % Set 9 7.5 17.99 55.13 15.13 7.8 12.596 38.60 40.58 8 9.974 30.57 52.95 8.3 5.613 17.20 73.52 8.7 2.174 6.66 89.74 9 0.981 3.01 95.37 gw 21.927 67.20 gw+MgCI2 20.515 62.87 Set 10 7.5 18.109 55.50 14.57 7.8 14.225 43.59 32.89 8 12.733 39.02 39.93 8.3 6.891 21.12 67.49 8.7 2.481 7.60 88.30 9 1.095 3.36 94.83 gw 23.105 70.81 gw+MgCI2 21.738 66.62 Precipitate solution Set 9 7.5 0.536 1.64 7.8 15.946 48.87 8 25.392 77.81 8.3 49.976 153.15 8.7 51.09 156.57 9 41.87 128.31 Set 10 7.5 1.452 4.45 7.8 2.31 7.08 8 20.694 63.42 8.3 24.208 74.19 8.7 58.366 178.86 9 51.83 158.83 Data from ICP mg-Mg/L mg-K/L mg-Ca/L 509.3 172.6 439.8 506.8 174.1 430.5 501.5 171.2 426.1 498.4 170.8 416.9 489.6 170.1 403.4 483.5 171.1 397 92.30 167.80 496.90 505.10 171.6 450.5 843.3 170.3 393.8 839.5 172.5 391 834.7 173.6 385.1 894.8 171.1 366.7 830.9 169.8 365 815.8 167.6 358.1 91.37 167.00 486.60 805.40 163 380.3 0.4897 0 1.245 9.501 0.8534 33.34 17.55 2.952 57.13 38.67 6.259 116.7 27.22 3.549 118.1 23.52 3.457 92.99 5.117 0 5.559 21.19 0.972 34.07 73.1 6.497 115.6 70.83 5.981 109.2 106 APPENDIX C molor ratio pH P04 mmol/L Mg mmol/L K mmol/L Ca mmol/L Ca/Mg Ca/P04 Mg/P04 K/P04 Set 9 7.5 0.58 21.22 4.43 11.00 7.8 0.41 21.12 4.46 10.76 8 0.32 20.90 4.39 10.65 8.3 0.18 20.77 4.38 10.42 8.7 0.07 20.40 4.36 10.09 9 0.03 20.15 4.39 9.93 gw 0.71 3.85 4.30 12.42 3.23 17.56 5.44 6.08 gw+MgCI2 0.66 21.05 4.40 11.26 0.54 17.02 31.80 6.65 Set 10 7.5 0.58 35.14 4.37 9.85 7.8 0.46 34.98 4.42 9.78 8 0.41 34.78 4.45 9.63 8.3 0.22 37.28 4.39 9.17 8.7 0.08 34.62 4.35 9.13 9 0.04 33.99 4.30 8.95 gw 0.75 3.81 4.28 12.17 3.20 16.32 5.11 5.75 gw+MgCI2 0.70 33.56 4.18 9.51 0.28 13.56 47.86 5.96 Precipitate solution Set 9 7.5 0.02 0.02 0.00 0.03 1.53 1.80 1.18 0.00 7.8 0.51 0.40 0.02 0.83 2.11 1.62 0.77 0.04 8 0.82 0.73 0.08 1.43 1.95 1.74 0.89 0.09 8.3 1.61 1.61 0.16 2.92 1.81 1.81 1.00 0.10 8.7 1.65 1.13 0.09 2.95 2.60 1.79 0.69 0.06 9 1.35 0.98 0.09 2.32 2.37 1.72 0.73 0.07 Set 10 7.5 0.05 0.20 7.8 0.07 0.21 0.00 0.14 0.65 1.87 2.86 0.00 8 0.67 0.50 8.3 0.78 0.88 0.02 0.85 0.96 1.09 1.13 0.03 8.7 1.88 3.05 0.17 2.89 0.95 1.53 1.62 0.09 9 1.67 2.95 0.15 2.73 0.93 1.63 1.77 0.09 107 APPENDIX C PH mg mg-precipitate/L mg-Ca/L Ca/precipitate mg-P04/L P04/precipitate Set 1 7.5 27 135 27.94 20.70 35.91 26.60 8 28 140 35.54 25.39 41.11 29.36 8.5 32 160 38.38 23.99 44.80 28.00 8.5 45 225 51.36 22.83 53.63 23.84 9 32 160 38.73 24.21 39.31 24.57 9.5 38 190 45.96 24.19 43.46 22.87 Avg 23.55 Avg 25.87 Set 2 7.5 16 80 25.68 32.10 29.83 37.29 8 19 95 26.66 28.06 29.53 31.08 8.5 38 190 50.08 26.36 58.79 30.94 8.5 25 125 29.06 23.25 31.42 25.14 9 17 85 19.66 23.13 22.63 26.62 9.5 40 200 49.12 24.56 48.35 24.18 Avg 26.24 Avg 29.21 Set 3 7.5 23 115 32.01 27.83 38.44 33.43 8 28 140 35.09 25.06 39.61 28.29 8.3 62 310 72.52 23.39 78.25 25.24 8.7 7 35 13.67 39.06 14.28 40.80 9 27 135 35.09 25.99 36.46 27.01 Avg 28.27 Avg 30.95 Set 4 7.75 35.5 355 75.63 21.30 115.51 32.54 7.96 56.5 565 121.3 21.47 132.95 23.53 8.09 57.1 571 123.8 21.68 140.48 24.60 8.38 74.9 749 161.9 21.62 228.52 30.51 8.88 85.8 858 165.2 19.25 174.98 20.39 9.35 90.5 905 197.5 21.82 207.84 22.97 Avg 21.19 Avg 25.76 Set 5 7.63 8.7 87 17.94 20.62 22.74 26.14 7.91 32.5 325 73.36 22.57 94.72 29.15 8.01 43.4 434 96.59 22.26 113.09 26.06 8.29 81 810 191 23.58 158.78 19.60 8.65 70.8 708 161.2 22.77 167.91 23.72 8.9 120.7 1207 289.6 23.99 228.19 18.91 Avg 22.63 Avg 23.93 108 APPENDIX C PH Set 1 7.5 8 8.5 8.5 9 9.5 Set 2 7.5 8 8.5 8.5 9 9.5 Set 3 7.5 8 8.3 8.7 9 Set 4 7.75 7.96 8.09 8.38 8.88 9.35 Set 5 7.63 7.91 8.01 8.29 8.65 8.9 mg-Mg/L Mg/precipitate mg-K/L K/precipitate 1.29 1.70 1.69 2.45 1.80 2.25 Avg 1.23 1.26 2.30 1.35 0.96 2.46 Avg 1.46 1.58 3.37 0.58 1.60 Avg 3.885 6.426 6.465 8.064 7.995 9.225 Avg 1.239 4.191 5.569 9.812 9.127 14.09 Avg 0.95 1.21 1.06 1.09 1.13 1.19 1.10 1.53 1.33 1.21 1.08 1.13 1.23 1.25 1.27 1.13 1.09 1.66 1.19 1.27 1.09 1.14 1.13 1.08 0.93 1.02 1.07 1.42 1.29 1.28 1.21 1.29 1.17 1.28 0.8951 1.364 1.243 2.099 1.428 2.182 Avg 0.964 1 1.851 1.042 0.5369 2.384 Avg 0.1723 0 2.257 0.7583 0.8114 Avg 3.164 6.392 6.457 7.639 7.585 9.306 Avg 0.05 1.152 1.832 4.169 3.746 7.233 Avg 0.66 0.97 0.78 0.93 0.89 1.15 0.90 1.21 1.05 0.97 0.83 0.63 1.19 0.98 0.15 0.00 0.73 2.17 0.60 0.73 0.89 1.13 1.13 1.02 0.88 1.03 1.01 0.06 0.35 0.42 0.51 0.53 0.60 0.41 109 APPENDIX C PH mg mg-precipitate/L mg-Ca/L Ca/precipitate mg-P04/L P04/precipitate Set 6 7.54 12 120 33.41 27.84 49.01 40.84 7.73 34.6 346 69.92 20.21 92.26 26.66 8.07 32.9 329 70.2 21.34 84.57 25.70 8.31 51.9 519 106.2 20.46 120.06 23.13 8.76 34.1 341 76.35 22.39 81.29 23.84 9.18 85.8 858 173.9 20.27 224.66 26.18 Avg 22.08 Avg 27.73 Set 7 7.5 25 250 44.14 17.66 46.09 18.44 7.8 40.3 403 76.82 19.06 136.49 33.87 8 50.3 503 93.46 18.58 119.34 23.73 8.3 70.4 704 136.2 19.35 197.57 28.06 8.7 75.9 759 157.5 20.75 204.30 26.92 9 82.6 826 170 20.58 209.53 25.37 Avg 19.33 Avg 26.06 Set 8 7.5 12.4 124 15.67 12.64 22.81 18.40 7.8 31.4 314 55.53 17.68 91.57 29.16 8 31.1 311 67.49 21.70 104.69 33.66 8.3 63.4 634 118.5 18.69 162.27 25.59 8.7 71.3 713 137.3 19.26 185.83 26.06 9 73.5 735 144.1 19.61 175.92 23.93 Avg 18.26 Avg 26.14 Set 9 7.5 1.1 11 1.245 11.32 1.64 14.93 7.8 22.7 227 33.34 14.69 48.87 21.53 8 36.1 361 57.13 15.83 77.81 21.56 8.3 76.5 765 116.7 15.25 153.15 20.02 8.7 64.5 645 118.1 18.31 156.57 24.27 9 63.1 631 92.99 14.74 128.31 20.33 Avg 15.02 Avg 20.44 Set 10 7.5 4.45 7.8 6.5 65 5.559 8.55 7.08 10.89 8 63.42 8.3 29.5 295 34.07 11.55 74.19 25.15 8.7 101.7 1017 115.6 11.37 178.86 17.59 9 108.2 1082 109.2 10.09 158.83 14.68 Avg 10.39 Avg 17.08 110 APPENDIX C mg-Mg/L Mg/precipitate mg-K/L K/precipitate PH Set 6 7.54 7.73 8.07 8.31 8.76 9.18 Set 7 7.5 7.8 8 8.3 8.7 Set 8 7.5 7.8 8 8.3 8.7 9 Set 9 7.5 7.8 8 8.3 8.7 9 Set 10 7.5 7.8 8 8.3 8.7 9 3.648 7.829 7.651 11.31 7.611 17.86 Avg 5.696 9.498 11.66 17.42 18.69 20.47 Avg 3.038 9.86 12 21.8 22.56 25.21 Avg 0.4897 9.501 17.55 38.67 27.22 23.52 Avg 5.117 21.19 73.1 70.83 Avg 3.04 2.26 2.33 2.18 2.23 2.08 2.35 2.28 2.36 2.32 2.47 2.46 2.48 2.39 2.45 3.14 3.86 3.44 3.16 3.43 3.25 4.45 4.19 4.86 5.05 4.22 3.73 4.42 7.87 7.18 7.19 6.55 7.20 0.8974 3.008 2.562 4.068 2.48 7.357 Avg 1.684 2.786 3.467 4.783 4.823 6.719 Avg 0 1.073 1.375 3.556 3.143 3.779 Avg 0 0.8534 2.952 6.259 3.549 3.457 Avg 0.972 6.497 5.981 Avg 0.75 0.87 0.78 0.78 0.73 0.86 0.79 0.67 0.69 0.69 0.68 0.64 0.81 0.70 0.00 0.34 0.44 0.56 0.44 0.51 0.38 0.00 0.38 0.82 0.82 0.55 0.55 0.52 0.00 0.33 0.64 0.55 0.38 111 APPENDIX D APPENDIX D DATA FOR SECOND GROUP OF JAR TEST 112 APPENDIX D MgCI2(0ml) Data from LaChat P removal Data from LaChat PH mg-P/L mg-P04/L % mg-N/L mg-NH4/L Set 11 7.65 7.738 23.71 38.46 19.74 25.38 7.86 5.729 17.56 54.43 19.71 25.34 8.33 1.539 4.72 87.76 19.05 24.49 8.61 0.691 2.12 94.50 17.9 23.01 8.88 0.344 1.05 97.26 17.43 22.41 8.94 0.538 1.65 95.72 15.48 19.90 gw 11.643 35.68 2.66 3.42 gw+NH4CI(3ml) 12.574 38.53 19.98 25.69 Set 12 7.72 7.367 22.58 31.90 46.81 60.18 8.02 3.007 9.22 72.20 46.1 59.27 8.18 2.002 6.14 81.49 43.96 56.52 8.47 1.025 3.14 90.52 41.88 53.85 8.83 0.22 0.67 97.97 42.06 54.08 8.86 0.479 1.47 95.57 36.45 46.86 gw 10.107 30.97 1.83 2.35 gw+NH4CI(6ml) 10.818 33.15 48.12 61.87 Set 13 7.64 7.863 24.10 33.21 91.72 117.93 7.79 6.405 19.63 45.60 90.27 116.06 8.05 3.927 12.03 66.65 86.84 111.65 8.31 1.601 4.91 86.40 83.7 107.61 8.67 0.477 1.46 95.95 74.77 96.13 8.79 0.619 1.90 94.74 73.46 94.45 gw 11.773 36.08 gw+NH4CI(10ml) 11.105 34.03 94.1 120.99 Precipitate solution Set 11 7.65 3.418 10.47 2.32 2.98 7.86 10.814 33.14 2.88 3.70 8.33 25.758 78.94 2.18 2.80 8.61 36.116 110.68 1.69 2.17 8.88 14.242 43.64 1.92 2.47 8.94 11.86 36.35 1.83 2.35 Set 12 7.72 2.344 7.18 2.59 3.33 8.02 13.982 42.85 2.79 3.59 8.18 18.622 57.07 2.26 2.91 8.47 11.088 33.98 2.66 3.42 8.83 15.976 48.96 3.19 4.10 8.86 10.294 31.55 2.78 3.57 Set 13 7.64 7.79 4.074 12.48 3.5 4.50 8.05 7.334 22.48 3.51 4.51 8.31 22.726 69.64 2.83 3.64 8.67 13.2 40.45 3.84 4.94 8.79 8.746 26.80 3.69 4.74 113 APPENDIX D MgCI2(0ml) Data from ICP P04 pH mg-Mg/Lmg-K/Lmg-Ca/L Set 11 7.65 65.7 198.4 307.3 0.25 7.86 66.34 200.2 304.5 0.18 8.33 65.73 199.3 290.7 0.05 8.61 64.17 198.9 277.9 0.02 8.88 64.27 201.5 247.3 0.01 8.94 62.93 206.5 187.1 0.02 gw 66.79 201 313.8 0.38 w+NH4CI(3ml) 65.25 196 309 0.41 Set 12 7.72 65.31 199.1 304.8 0.24 8.02 65.13 198.7 294.7 0.10 8.18 64.35 195.7 288.2 0.06 8.47 63.93 196.7 280.7 0.03 8.83 63.08 201 209.3 0.01 8.86 61.31 203.2 176.5 0.02 gw 66.78 200.9 315.9 0.33 w+NH4CI(6ml) 64.63 192.4 306.9 0.35 Set 13 7.64 64.39 194.1 300.2 0.25 7.79 64.31 193.2 298 0.21 8.05 64.3 195 292.6 0.13 8.31 63.09 194 277.2 0.05 8.67 61.48 194.4 261.7 0.02 8.79 60.57 196.1 193.3 0.02 gw 66.85 200.5 314.5 0.38 gw+NH4CI(10ml) 64.61 193.7 303.5 0.36 Precipitate solution Set 11 7.65 1.508 1.048 5.259 0.11 7.86 2.525 3.643 28.25 0.35 8.33 3.349 4.757 61.94 0.83 8.61 5.618 9.422 104.6 1.17 8.88 0.46 8.94 2.694 2.783 114.9 0.38 Set 12 7.72 1.62 1.123 7.148 0.08 8.02 1.822 1.988 39.12 0.45 8.18 2.466 2.977 51.75 0.60 8.47 1.796 2.467 35.29 0.36 8.83 2.711 3.915 60.93 0.52 8.86 2.897 3.836 129.1 0.33 Set 13 7.64 7.79 1.33 0.7349 11.09 0.13 8.05 1.607 3.055 23.34 0.24 8.31 2.962 3.747 67.28 0.73 8.67 2.474 3.436 57.4 0.43 8.79 1.52 1.159 71.25 0.28 NH4 Mg K Ca molor ratio mmol/L Ca/Mg Ca/PQ4 1.41 2.74 5.09 7.68 1.41 2.76 5.13 7.61 1.36 2.74 5.11 7.27 1.28 2.67 5.10 6.95 1.25 2.68 5.17 6.18 1.11 2.62 5.29 4.68 0.19 2.78 5.15 7.85 2.82 20.89 1.43 2.72 5.03 7.73 2.84 19.05 3.34 2.72 5.11 7.62 3.29 2.71 5.09 7.37 3.14 2.68 5.02 7.21 2.99 2.66 5.04 7.02 3.00 2.63 5.15 5.23 2.60 2.55 5.21 4.41 0.13 2.78 5.15 7.90 2.84 24.22 3.44 2.69 4.93 7.67 2.85 21.99 6.55 2.68 4.98 7.51 6.45 2.68 4.95 7.45 6.20 2.68 5.00 7.32 5.98 2.63 4.97 6.93 5.34 2.56 4.98 6.54 5.25 2.52 5.03 4.83 2.79 5.14 7.86 2.82 20.70 6.72 2.69 4.97 7.59 2.82 21.18 0.17 0.06 0.03 0.13 2.09 1.19 0.21 0.11 0.09 0.71 6.71 2.02 0.16 0.14 0.12 1.55 11.10 1.86 0.12 0.23 0.24 2.62 11.17 2.24 0.14 0.13 0.11 0.07 2.87 25.59 7.51 0.19 0.07 0.03 0.18 2.65 2.36 0.20 0.08 0.05 0.98 12.88 2:17 0.16 0.10 0.08 1.29 12.59 2.15 0.19 0.07 0.06 0.88 11.79 2.47 0.23 0.11 0.10 1.52 13.49 2.96 0.20 0.12 0.10 3.23 26.74 9.72 0.25 0.06 0.02 0.28 5.00 2.11 0.25 0.07 0.08 0.58 8.71 2.47 0.20 0.12 0.10 1.68 13.63 2.29 0.27 0.10 0.09 1.44 13.92 3.37 0.26 0.06 0.03 1.78 28.13 6.31 114 APPENDIX D MgCI2(3ml) Set 14 Data from LaChat P removal Data from LaChat pH mg-P/L mg-P04/L Efficiency % mg-N/L mg-NH4/L P04 mmol/ L NH4 mmol/L 6.97 51.56 158.00 39.50 122.96 158.09 1.66 8.78 7.18 32.38 99.22 62.01 128.88 165.70 1.04 9.21 7.6 14.72 45.11 82.72 94.16 121.06 0.47 6.73 8.01 5.91 18.11 93.06 119.55 153.70 0.19 8.54 8.31 2.93 8.98 96.56 110.92 142.61 0.09 7.92 8.71 1.16 3.55 98.64 109.07 140.23 0.04 7.79 nl) 85.22 261.14 128.75 165.54 2.75 9.20 Set 15 6.73 72.83 223.19 12.25 185.92 239.04 2.35 13.28 6.87 57.88 177.36 30.27 180.87 232.55 1.87 12.92 7.07 46.26 141.76 44.26 176.82 227.34 1.49 12.63 7.25 33.17 101.64 60.04 185.19 238.10 1.07 13.23 7.79 11.46 35.11 86.20 172.59 221.90 0.37 12.33 8.45 2.16 6.62 97.40 181.04 232.76 0.07 12.93 gw+NH4CI(30ml) 83.00 254.35 206.93 266.05 2.68 14.78 Precipitate solution Set 14 6.97 34.53 105.81 2.31 2.96 1.11 0.16 7.18 55.76 170.87 3.47 4.46 1.80 0.25 7.6 41.82 128.16 5.88 7.56 1.35 0.42 8.01 57.82 177.20 2.13 2.74 1.87 0.15 8.31 55.74 170.80 5.48 7.04 1.80 0.39 8.71 54.52 167.07 1.67 2.15 1.76 0.12 Set 15 6.73 12.80 39.23 2.88 3.71 0.41 0.21 6.87 25.71 78.80 4.23 5.43 0.83 0.30 7.07 32.71 100.25 5.23 6.73 1.06 0.37 7.25 42.29 129.61 4.93 6.33 1.36 0.35 7.79 56.58 173.40 4.59 5.90 1.83 0.33 8.45 55.24 169.28 5.95 7.66 1.78 0.43 115 APPENDIX D MgCI2(3ml) PH Set 14 Data from ICP molor ratio mg-Mg/L mg-K/L mg-Ca/L ^ m m K Q | / L m m ^ L Ca/Mg Ca/P04 NH4/PQ4 6.97 109 360.1 341.5 4.54 9.23 8.54 7.18 107.8 349.1 305.8 4.49 8.95 7.65 7.6 105.2 349.2 276.9 4.38 8.95 6.92 8.01 100.4 342.3 256.8 4.18 8.78 6.42 8.31 100.8 341.9 248.3 4.20 8.77 6.21 8.71 97.89 343.8 235.7 4.08 8.82 5.89 gw+NH4CI(20ml) 107 326.3 382.6 4.46 8.37 9.57 3.35 Set 15 6.73 109.1 342.4 366 4.55 8.78 9.15 6.87 109.4 350.6 350.7 4.56 8.99 8.77 7.07 105.7 352.1 321.8 4.40 9.03 8.05 7.25 107 353.1 299.5 4.46 9.05 7.49 7.79 101.5 344.1 265.5 4.23 8.82 6.64 8.45 96.25 337.3 238.6 4.01 8.65 5.97 gw+NH4CI(30ml) 108.2 332.1 388.2 4.51 8.52 9.71 Precipitate solution Set 14 6.97 5.004 3.75 74.97 0.21 0.10 1.87 8.99 1 .68 0.15 7.18 8.982 8.505 120.8 0.37 0.22 3.02 8.07 1 .68 0.14 7.6 7.708 6.651 101.9 0.32 0.17 2.55 7.93 1 .89 0.31 8.01 11.54 11.04 145.4 0.48 0.28 3.64 7.56 1 .95 0.08 8.31 9.569 8.547 121.3 0.40 0.22 3.03 7.61 1 .69 0.22 8.71 10.09 9.536 122.5 0.42 0.24 3.06 7.28 1 .74 0.07 Set 15 6.73 1.542 6.87 3.517 7.07 4.784 7.25 7.165 7.79 7.613 8.45 9.199 1.331 23.67 3.045 51.39 3.92 74.37 6.088 98.71 5.88 103 7.368 119.7 0.06 0.03 0.15 0.08 0.20 0.10 0.30 0.16 0.32 0.15 0.38 0.19 0.59 9.21 1.28 8.77 1.86 9.33 2.47 8.27 2.58 8.12 2.99 7.81 1.43 0.50 1.55 0.36 1.76 0.35 1.81 0.26 1.41 0.18 1.68 0.24 116 APPENDIX D MgCI2(3ml) PH Set 16 6.99 7.2 7.54 7.81 8.13 8.5 gw+NH4CI(3ml) Set 17 7.02 7.31 7.67 8.17 8.4 8.71 gw+NH4CI(6ml) Set 18 6.95 7.3 7.74 8.01 8.42 8.74 gw+NH4CI(10ml) Precipitate solution Set 16 6.99 7.2 7.54 7.81 8.13 8.5 Set 17 7.02 7.31 7.67 8.17 8.4 8.71 Set 18 6.95 7.3 7.74 8.01 8.42 8.74 Data from LaChat P removal Data from LaChat mg-P/L E f f l t n C V "3-NH4/L m ^ L 14.16 10.07 4.18 2.38 1.00 0.29 37.00 43.39 30.86 12.80 7.30 3.05 0.89 113.37 61.73 72.78 88.71 93.56 97.31 99.21 31.71 32.93 30.96 30.81 30.32 28.78 33.49 40.77 42.34 39.80 39.61 38.98 37.01 43.06 0.46 0.32 0.13 0.08 0.03 0.01 1.19 NH4 mmol/L 2.26 2.35 2.21 2.20 2.17 2.06 2.39 14.75 8.31 3.83 1.13 0.52 0.52 36.49 45.20 25.46 II. 73 3.45 1.59 1.59 III. 81 59.57 77.23 89.51 96.91 98.57 98.57 40.30 40.61 40.02 39.90 38.81 36.99 41.85 51.82 52.21 51.45 51.30 49.90 47.55 53.81 0.48 0.27 0.12 0.04 0.02 0.02 1.18 2.88 2.90 2.86 2.85 2.77 2.64 2.99 15.93 48.83 55.76 69.33 89.14 0.51 4.95 7.64 23.40 78.80 70.38 90.49 0.25 5.03 3.02 9.24 91.63 67.50 86.78 0.10 4.82 1.50 4.61 95.82 67.02 86.17 0.05 4.79 0.50 1.54 98.60 66.92 86.04 0.02 4.78 0.09 0.27 99.75 62.47 80.32 0.00 4.46 36.02 110.38 69.88 89.84 1.16 4.99 122.43 375.20 131.33 402.46 137.46 421.25 150.50 461.21 89.09 273.03 77.75 238.25 101.21 310.15 143.21 438.86 140.94 431.91 148.62 455.45 71.47 219.02 72.57 222.40 115.69 354.55 140.64 430.99 157.83 483.68 78.55 240.73 75.92 232.66 72.24 221.37 1.69 2.17 1.30 1.67 1.07 1.38 1.18 1.51 1.88 2.41 2.14 2.76 2.20 2.83 2.03 2.60 1.64 2.11 1.48 1.91 1.57 2.02 1.53 1.96 1.22 1.57 1.74 2.24 1.83 2.35 1.62 2.09 2.59 3.33 1.57 2.01 3.95 0.12 4.24 0.09 4.43 0.08 4.85 0.08 2.87 0.13 2.51 0.15 3.26 0.16 4.62 0.14 4.55 0.12 4.79 0.11 2.31 0.11 2.34 0.11 3.73 0.09 4.54 0.12 5.09 0.13 2.53 0.12 2.45 0.18 2.33 0.11 117 APPENDIX D MgCI2(3ml) Set 16 PH Data from ICP mg-Mg/L mg-K/L mg-Ca/L molor ratio mmoV mm K o^Lmmol /L C a / M 9 C a / P ° 4 N H 4 / P ° 4 6.99 162.8 445.4 360.4 6.78 11.42 9.01 7.2 160.5 454.2 332.7 6.69 11.65 8.32 7.54 161 452 313.8 6.71 11.59 7.85 7.81 155.1 430.2 280.3 6.46 11.03 7.01 8.13 153.6 429.5 285.8 6.40 11.01 7.15 8.5 156.2 433.4 273.4 6.51 11.11 6.84 gw+NH4CI(3ml) 179.6 441.2 479.7 7.48 11.31 11.99 1.60 10.05 2.00 Set 17 7.02 140.1 414.5 372 5.84 10.63 9.30 7.31 142.2 446.4 340.6 5.93 11.45 8.52 7.67 143.7 445 310.3 5.99 11.41 7.76 8.17 137.9 451.6 292.2 5.75 11.58 7.31 8.4 136.8 446.1 294.7 5.70 11.44 7.37 8.71 137.8 459.4 281.3 5.74 11.78 7.03 gw+NH4CI(6ml) 155.2 448.5 488.7 6.47 11.50 12.22 1.89 10.38 2.54 Set 18 6.95 150.3 450.2 389.6 6.26 11.54 9.74 7.3 146 448.9 338.1 6.08 11.51 8.45 7.74 119.6 336.9 265 4.98 8.64 6.63 8.01 143 440.7 289.9 5.96 11.30 7.25 8.42 143.4 440.1 286.1 5.98 11.28 7.15 8.74 141.8 444.3 276.8 5.91 11.39 6.92 gw+NH4CI(10ml) 159.6 426.4 492.6 6.65 10.93 12.32 1.85 10.60 4.30 Precipitate solution Set 16 6.99 19.61 15.55 221.5 0.82 0.40 5.54 6.78 1.40 0.03 7.2 21.69 19.66 242.5 0.90 0.50 6.06 6.71 1.43 0.02 7.54 24.99 23.02 275.7 1.04 0.59 6.89 6.62 1.55 0.02 7.81 31.49 29.96 323.5 1.31 0.77 8.09 6.16 1.67 0.02 8.13 18.38 16.39 199.4 0.05 8.5 16.39 13.74 180.9 0.68 0.35 4.52 6.62 1.80 0.06 Set 17 7.02 13.99 7.31 23 7.67 26.47 8.17 30.09 8.4 16.28 8.71 15.14 15.35 183.1 29.11 278.8 33.31 318.3 37.36 346.2 19.7 184.8 19.01 176.8 0.58 0.39 0.96 0.75 1.10 0.85 1.25 0.96 0.68 0.51 0.63 0.49 4.58 7.85 6.97 7.27 7.96 7.21 8.66 6.90 4.62 6.81 4.42 7.01 1.40 0.05 1.51 0.03 1.75 0.03 1.81 0.02 2.00 0.05 1.89 0.05 Set 18 6.95 17.91 7.3 26.46 7.74 32.19 8.01 16.21 8.42 15.55 8.74 15.98 18.47 243.5 27.75 325.6 34.62 402.9 16.02 195.5 14.95 183.3 15.3 190.9 0.75 0.47 1.10 0.71 1.34 0.89 0.68 0.41 0.65 0.38 0.67 0.39 6.09 8.16 8.14 7.38 10.07 7.51 4.89 7.24 4.58 7.07 4.77 7.17 1.63 0.02 1.79 0.03 1.98 0.03 1.93 0.05 1.87 0.08 2.05 0.05 118 APPENDIX D MgCI2(15ml) Data from LaChat P removal Data from LaChat PH mg-P/L mg-P04/L Efficiency % mg-N/L mg-NH4/L P04 mmol/L NH4 mmol/L Set 19 6.76 72.24 221.39 13.67 60.83 78.20 2.33 4.34 7.02 47.24 144.76 43.55 59.18 76.09 1.52 4.23 7.4 21.64 66.33 74.14 55.39 71.22 0.70 3.96 7.65 12.82 39.29 84.68 51.37 66.05 0.41 3.67 8.16 4.13 12.65 95.07 53.65 68.98 0.13 3.83 8.59 1.62 4.96 98.07 48.79 6273 0.05 3.49 v+NH4CI(8ml) 83.69 256.46 53.97 69.40 2.70 3.86 Set 20 6.81 68.59 210.18 13.14 132.07 169.81 2.21 9.43 6.99 44.12 135.21 44.12 128.02 164.60 1.42 9.14 7.3 25.61 78.49 67.56 129.44 166.43 0.83 9.25 7.65 13.82 42.34 82.50 121.37 156.05 0.45 8.67 8.08 5.09 15.60 93.55 119.80 154.03 0.16 8.56 8.66 2.26 6.93 97.14 112.42 144.54 0.07 8.03 gw+NH4CI(20ml) 78.96 241.97 139.85 179.80 2.55 9.99 Set 21 6.88 64.50 197.67 23.92 222.16 285.64 2.08 15.87 7.05 46.73 143.21 44.88 200.38 257.64 1.51 14.31 7.32 30.13 92.34 64.46 212.46 273.16 0.97 15.18 7.78 10.94 33.52 87.10 190.50 244.93 0.35 13.61 8.23 5.67 17.36 93.32 179.29 230.51 0.18 12.81 8.72 1.49 4.56 98.25 174.90 224.87 0.05 12.49 gw+NH4CI(30ml) 84.79 259.83 189.62 243.80 2.74 13.54 Precipitate solution Set 19 6.76 18.83 57.72 2.26 2.91 0.61 0.16 7.02 39.93 122.37 0.09 0.11 1.29 0.01 7.4 46.52 142.57 0.01 0.02 1.50 0.00 7.65 47.97 147.01 0.00 0.00 1.55 0.00 8.16 42.37 129.84 0.00 0.00 1.37 0.00 "Set 20 8.59 43.86 134.40 0.00 0.00 1.41 0.00 6.81 22.49 68.91 4.63 5.96 0.73 0.33 6.99 45.15 138.35 1.00 1.28 1.46 0.07 7.3 38.90 119.21 0.52 0.67 1.25 0.04 7.65 59.35 181.87 0.21 0.27 1.91 0.02 8.08 83.66 256.39 0.40 0.52 2.70 0.03 8.66 61.17 187.44 0.21 0.27 1.97 0.02 Set 21 6.88 23.99 73.51 3.88 4.99 0.77 0.28 7.05 29.71 91.05 1.08 1.38 0.96 0.08 7.32 37.46 114.81 0.75 0.96 1.21 0.05 7.78 48.60 148.92 0.52 0.66 1.57 0.04 8.23 59.97 183.79 0.30 0.38 1.93 0.02 8.72 72.76 222.97 0.27 0.34 2.35 0.02 119 APPENDIX D MgCI2(15ml) Data from ICP molor ratio PH mg-Mg/L mg-K/L mg-Ca/L Mg mmol/L K Ca mmol/L mmol/L Ca/Mg Ca/P04 NH4/P04 Set 19 6.76 248.2 361.4 369.8 10.34 9.27 9.25 7.02 246.5 366.8 323.8 10.27 9.41 8.10 7.4 239.7 358 289.3 9.99 9.18 7.23 7.65 234.6 344.7 272.3 9.78 8.84 6.81 8.16 230.6 346.8 257.1 9.61 8.89 6.43 8.59 230.8 360.9 248.4 9.62 9.25 6.21 gw+NH4CI(8ml) 247.8 348.7 385.4 10.33 8.94 9.64 0.93 3.57 1.43 Set 20 6.81 233.2 339 342.8 9.72 8.69 8.57 6.99 234.6 347.5 325.8 9.78 8.91 8.15 7.3 237.4 352.4 297.3 9.89 9.04 7.43 7.65 230.9 348.9 303.6 9.62 8.95 7.59 8.08 230.2 349.5 261.8 9.59 8.96 6.55 8.66 220 340.9 243 9.17 8.74 6.08 gw+NH4CI(20ml) 255.2 353.1 390.6 10.63 9.05 9.77 0.92 3.83 3.92 Set 21 6.88 246.3 353.4 345.8 10.26 9.06 8.65 7.05 240.3 345.6 322.3 10.01 8.86 8.06 7.32 236.7 347 301.5 9.86 8.90 7.54 7.78 235.7 349.4 286.9 9.82 8.96 7.17 8.23 224.1 342.4 251.6 9.34 8.78 6.29 8.72 218.5 337.3 239.1 9.10 8.65 5.98 gw+NH4CI(30ml) 242.7 342.6 376.1 10.11 8.78 9.40 0.93 3.44 4.95 Precipitate solution Set 19 6.76 4.664 1.811 33.51 0.19 0.05 0.84 4.31 1.38 0.27 7.02 11.42 4.464 79.8 0.48 0.11 2.00 4.19 1.55 0.00 7.4 15.07 5.777 103.2 0.63 0.15 2.58 4.11 1.72 0.00 7.65 16.15 6.371 108.3 0.67 0.16 2.71 4.02 1.75 0.00 8.16 15.27 5.942 98.89 0.64 0.15 2.47 3.89 1.81 0.00 8.59 16.76 6.05 109 0.70 0.16 2.73 3.90 1.93 0.00 Set 20 6.81 6.944 3.497 47.44 0.29 0.09 1.19 4.10 1.64 0.46 6.99 15.34 7.752 102.9 0.64 0.20 2.57 4.02 1.77 0.05 7.3 13.07 5.797 86.85 0.54 0.15 2.17 3.99 1.73 0.03 7.65 20.59 9.659 132.6 0.86 0.25 3.32 3.86 1.73 0.01 8.08 30.91 14.88 195.6 1.29 0.38 4.89 3.80 1.81 0.01 8.66 25.11 11.29 154.8 1.05 0.29 3.87 3.70 1.96 0.01 Set 21 6.88 5.536 2.051 40.57 0.23 0.05 1.01 4.40 1.31 0.36 7.05 8.465 3.378 62.76 0.35 0.09 1.57 4.45 1.64 0.08 7.32 11.39 3.901 82.63 0.47 0.10 2.07 4.35 1.71 0.04 7.78 15.02 5.041 107.6 0.63 0.13 2.69 4.30 1.72 0.02 8.23 19.28 6.49 135.5 0.80 0.17 3.39 4.22 1.75 0.01 8.72 21.57 7.32 144.8 0.90 0.19 3.62 4.03 1.54 0.01 120 A P P E N D I X D Precipitate solution PH Set 11 7.65 7.86 8.33 8.61 8.88 8.94 Set 12 7.72 8.02 8.18 8.47 8.83 8.86 Set 13 7.64 7.79 8.05 8.31 8.67 8.79 Set 14 6.97 7.18 7.6 8.01 8.31 8.71 Set 15 6.73 6.87 7.07 7.25 7.79 8.45 mg mg-crystal/L mg-Ca/L Ca/crystal mg-P04/L P04/crystal 3.4 34 5.259 15.47 10.47 30.81 13.4 134 28.25 21.08 33.14 24.73 25.5 255 61.94 24.29 78.94 30.96 42.4 424 104.6 24.67 110.68 26.10 41.6 208 43.64 20.98 84.80 339.2 114.9 33.87 36.35 10.71 5.8 58 7.148 12.32 7.18 12.38 15.4 154 39.12 25.40 42.85 27.82 22.1 221 51.75 23.42 57.07 25.82 14.8 148 35.29 23.84 33.98 22.96 45.6 228 60.93 26.72 48.96 21.47 94.10 376.4 129.1 34.30 31.55 8.38 4.1 9.8 26.4 43.6 52.7 81.1 136.6 110.3 160.9 132.2 141.5 27.5 62.9 77.7 110.3 108.5 121.7 41 98 264 218 210.8 324.4 546.4 441.2 643.6 528.8 566 110 251.6 310.8 441.2 434 486.8 11.09 23.34 67.28 57.4 71.25 74.97 120.8 101.9 145.4 121.3 122.5 23.67 51.39 74.37 98.71 103 119.7 27.05 23.82 25.48 26.33 33.80 23.11 22.11 23.10 22.59 22.94 21.64 21.52 20.43 23.93 22.37 23.73 24.59 12.48 22.48 69.64 40.45 26.80 105.81 170.87 128.16 177.20 170.80 167.07 39.23 78.80 100.25 129.61 173.40 169.28 30.45 22.93 26.38 18.56 12.71 32.62 31.27 29.05 27.53 32.30 29.52 35.66 31.32 32.26 29.38 39.95 34.77 121 APPENDIX D Precipitate solution PH Set 11 7.65 7.86 8.33 8.61 8.88 8.94 Set 12 7.72 8.02 8.18 8.47 8.83 8.86 Set 13 7.64 7.79 8.05 8.31 8.67 8.79 Set 14 6.97 7.18 7.6 8.01 8.31 8.71 Set 15 6.73 6.87 7.07 7.25 7.79 8.45 mg-NH4/LNH4/crystal 2.98 8.77 3.70 2.76 2.80 1.10 2.17 0.51 2.47 1.19 2.35 0.69 3.33 5.74 3.59 2.33 2.91 1.31 3.42 2.31 4.10 1.80 3.57 0.95 mg-Mg/L Mg/crystal 1.508 4.44 2.525 1.88 3.349 1.31 5.618 1.33 2.694 0.79 1.62 2.79 1.822 1.18 2.466 1.12 1.796 1.21 2.711 1.19 2.897 0.77 mg-K/L K/crystal 1.048 3.08 3.643 2.72 4.757 1.87 9.422 2.22 2.783 0.82 1.123 1.94 1.988 1.29 2.977 1.35 2.467 1.67 3.915 1.72 3.836 1.02 4.50 10.98 4.51 4.60 3.64 1.38 4.94 2.26 4.74 2.25 2.96 0.91 4.46 0.82 7.56 1.71 2.74 0.43 7.04 1.33 2.15 0.38 3.71 3.37 5.43 2.16 6.73 2.16 6.33 1.44 5.90 1.36 7.66 1.57 1.33 3.24 1.607 1.64 2.962 1.12 2.474 1.13 I. 52 0.72 5.004 1.54 8.982 1.64 7.708 1.75 II. 54 1.79 9.569 1.81 10.09 1.78 1.542 1.40 3.517 1.40 4.784 1.54 7.165 1.62 7.613 1.75 9.199 1.89 0.7349 1.79 3.055 3.12 3.747 1.42 3.436 1.58 I. 159 0.55 3.75 1.16 8.505 1.56 6.651 1.51 II. 04 1.72 8.547 1.62 9.536 1.68 1.331 1.21 3.045 1.21 3.92 1.26 6.088 1.38 5.88 1.35 7.368 1.51 122 A P P E N D I X D Precipitate solution PH Set 16 6.99 7.2 7.54 7.81 8.13 8.5 Set 17 7.02 7.31 7.67 8.17 8.4 8.71 Set 18 6.95 7.3 7.74 8.01 8.42 8.74 Set 19 6.76 7.02 7.4 7.65 8.16 8.59 Set 20 6.81 6.99 7.3 7.65 8.08 8.66 Set 21 6.88 7.05 7.32 7.78 8.23 8.72 mg mg-crystal/L 115.40 1154 123.80 1238 127.30 1273 160.70 1607 188.40 942 197.00 788 90.70 907 139.10 1391 156.10 1561 166.80 1668 165.00 825 209.80 839.2 115.00 1150 152.70 1527 188.40 1884 164.10 820.5 188.50 754 198.80 795.2 34.9 174.5 81 405 121.5 486 124 496 117.2 468.8 125.8 503.2 47.3 236.5 107.1 535.5 105.7 422.8 161.6 646.4 195.5 782 190.9 763.6 27.3 136.5 60.2 301 98.3 393.2 124.6 498.4 143.6 574.4 169.2 676.8 mg-Ca/L Ca/crystal 221.5 19.19 242.5 19.59 275.7 21.66 323.5 20.13 199.4 21.17 180.9 22.96 183.1 20.19 278.8 20.04 318.3 20.39 346.2 20.76 184.8 22.40 176.8 21.07 243.5 21.17 325.6 21.32 402.9 21.39 195.5 23.83 183.3 24.31 190.9 24.01 33.51 19.20 79.8 19.70 103.2 21.23 108.3 21.83 98.89 21.09 109 21.66 47.44 20.06 102.9 19.22 86.85 20.54 132.6 20.51 195.6 25.01 154.8 20.27 40.57 29.72 62.76 20.85 82.63 21.01 107.6 21.59 135.5 23.59 144.8 21.39 mg-P04/L P04/crystal 375.20 32.51 402.46 32.51 421.25 33.09 461.21 28.70 273.03 28.98 238.25 30.24 310.15 34.20 438.86 31.55 431.91 27.67 455.45 27.31 219.02 26.55 222.40 26.50 354.55 30.83 430.99 28.22 483.68 25.67 240.73 29.34 232.66 30.86 221.37 27.84 57.72 33.08 122.37 30.22 142.57 29.34 147.01 29.64 129.84 27.70 134.40 26.71 68.91 29.14 138.35 25.84 119.21 28.20 181.87 28.14 256.39 32.79 187.44 24.55 73.51 53.85 91.05 30.25 114.81 29.20 148.92 29.88 183.79 32.00 222.97 32.95 123 APPENDIX D Precipitate solution PH mg-NH4/L NH4/crystal mg-Mg/L Mg/crystal mg-K/L K/crystal Set 16 6.99 2.17 0.19 19.61 1.70 15.55 1.35 7.2 1.67 0.13 21.69 1.75 19.66 1.59 7.54 1.38 0.11 24.99 1.96 23.02 1.81 7.81 1.51 0.09 31.49 1.96 29.96 1.86 8.13 2.41 0.26 18.38 1.95 16.39 1.74 8.5 2.76 0.35 16.39 2.08 13.74 1.74 Set 17 7.02 2.83 0.31 13.99 1.54 15.35 1.69 7.31 2.60 0.19 23 1.65 29.11 2.09 7.67 2.11 0.14 26.47 1.70 33.31 2.13 8.17 1.91 0.11 30.09 1.80 37.36 2.24 8.4 2.02 0.24 16.28 1.97 19.7 2.39 8.71 1.96 0.23 15.14 1.80 19.01 2.27 Set 18 6.95 1.57 0.14 17.91 1.56 18.47 1.61 7.3 2.24 0.15 26.46 1.73 27.75 1.82 7.74 2.35 0.12 32.19 1.71 34.62 1.84 8.01 2.09 0.25 16.21 1.98 16.02 1.95 8.42 3.33 0.44 15.55 2.06 14.95 1.98 8.74 2.01 0.25 15.98 2.01 15.3 1.92 Set 19 6.76 2.91 1.67 4.664 2.67 1.811 1.04 7.02 0.11 0.03 11.42 2.82 4.464 1.10 7.4 0.02 0.00 15.07 3.10 5.777 1.19 7.65 0.00 0.00 16.15 3.26 6.371 1.28 8.16 0.00 0.00 15.27 3.26 5.942 1.27 8.59 0.00 0.00 16.76 3.33 6.05 1.20 Set 20 6.81 5.96 2.52 6.944 2.94 3.497 1.48 6.99 1.28 0.24 15.34 2.86 7.752 1.45 7.3 0.67 0.16 13.07 3.09 5.797 1.37 7.65 0.27 0.04 20.59 3.19 9.659 1.49 8.08 0.52 0.07 30.91 3.95 14.88 1.90 8.66 0.27 0.04 25.11 3.29 11.29 1.48 Set 21 6.88 4.99 3.66 5.536 4.06 2.051 1.50 7.05 1.38 0.46 8.465 2.81 3.378 1.12 7.32 0.96 0.24 11.39 2.90 3.901 0.99 7.78 0.66 0.13 15.02 3.01 5.041 1.01 8.23 0.38 0.07 19.28 3.36 6.49 1.13 8.72 0.34 0.05 21.57 3.19 7.32 1.08 124 APPENDIX E APPENDIX E DATA FOR CONDITIONAL SOLUBILITY TEST 125 APPENDIX E Conditional Solubility Determination Distilled Water with Greenhouse grown crystals For all tests, sample volume = 1.5 L, crystal mass = 1.5 g, stirrer speed = 70 rpm, temp = 25°C pH adjusted with HC1 and NaOH 24 Hour Reaction pH Mg Ca K P04-P Mg Ca K P04-P mg/L mg/L mg/L mg/L mol/L mol/L mol/L mol/L 6.92 6.46 65.98 2.562 21.785 2.66E-04 1.65E-03 6.55E-05 7.03E-04 7.14 4.57 27.37 1.385 9.652 1.88E-04 6.83E-04 3.54E-05 3.12E-04 6.99 4.541 24.57 4.588 7.816 1.87E-04 6.13E-04 1.17E-04 2.52E-04 7.16 3.825 21.52 1.144 7.539 1.57E-04 5.37E-04 2.93E-05 2.43E-04 7.06 3.874 21.69 2.078 7.594 1.59E-04 5.41 E-04 5.31 E-05 2.45E-04 7.05 3.722 21.05 1.955 7.41 1.53E-04 5.25E-04 5.00E-05 2.39E-04 6.37 7.119 93.57 2.441 30.103 2.93E-04 2.33E-03 6.24E-05 9.72E-04 6.73 6.117 51.62 2.1 16.545 2.52E-04 1.29E-03 5.37E-05 5.34E-04 7.2 4.701 25.12 1.664 9.016 1.93E-04 6.27E-04 4.26E-05 2.91 E-04 7.26 3.907 21.3 1.358 7.958 1.61E-04 5.31 E-04 3.47E-05 2.57E-04 7.24 . 3.954 20.58 1.899 7.651 1.63E-04 5.13E-04 4.86E-05 2.47E-04 7.5 3.396 16.54 1.29 6.92 1.40E-04 4.13E-04 3.30E-05 2.23E-04 7.19 7.009 72.96 2.5 23.9 2.88E-04 1.82E-03 6.39E-05 7.72E-04 7.35 5.346 39.11 1.731 13.664 2.20E-04 9.76E-04 4.43E-05 4.41 E-04 7.54 4.623 22.56 1.487 8.048 1.90E-04 5.63E-04 3.80E-05 2.60E-04 7.61 3.869 19.74 1.951 7.429 1.59E-04 4.93E-04 4.99E-05 2.40E-04 7.83 3.597 16.63 1.832 6.837 1.48E-04 4.15E-04 4.69E-05 2.21 E-04 8.39 2.492 10.95 1.387 6 1.03E-04 2.73E-04 3.55E-05 1.94E-04 7.26 5.075 52.76 0.9983 19.126 2.09E-04 1.32E-03 2.55E-05 6.18E-04 7.28 4.065 29.98 0.7425 11.89 1.67E-04 7.48E-04 1.90E-05 3.84E-04 7.55 3.174 15.72 0.4945 7.066 1.31E-04 3.92E-04 1.26E-05 2.28E-04 7.7 2.607 13.16 0.3193 6.641 1.07E-04 3.28E-04 8.17E-06 2.14E-04 8.15 2.203 9.697 0.6117 5.709 9.06E-05 2.42E-04 1.56E-05 1.84E-04 8.62 1.476 7.001 0.5409 5.425 6.07E-05 1.75E-04 1.38E-05 1.75E-04 126 A P P E N D I X E Ca:P Mg:P PH Mixture Mixture Molar Molar Ps pPs Ratio Ratio 6.92 2.02E-14 13.70 2.34 0.38 7.14 1.42E-15 14.85 2.19 0.60 6.99 3.39E-15 14.47 2.43 0.74 7.16 6.02E-16 15.22 2.21 0.65 7.06 1.12E-15 14.95 2.21 0.65 7.05 9.62E-16 15.02 2.20 0.64 6.37 4.15E-14 13.38 2.40 0.30 6.73 9.3E-15 14.03 2.41 0.47 7.2 1.5E-15 14.82 2.15 0.66 7.26 7.62E-16 15.12 2.07 0.63 7.24 1E-15 15.00 2.08 0.66 7.5 4.25E-16 15.37 1.85 0.63 7.19 2.59E-14 13.59 2.36 0.37 7.35 4.19E-15 14.38 2.21 0.50 7.54 1.06E-15 14.98 2.17 0.73 7.61 9.38E-16 15.03 2.05 0.66 7.83 6.35E-16 15.20 1.88 0.67 8.39 1.93E-16 15.72 1.41 0.53 7.26 4.33E-15 14.36 2.13 0.34 7.28 9.12E-16 15.04 1.95 0.44 7.55 1.48E-16 15.83 1.72 0.57 7.7 6.17E-17 16.21 1.53 0.50 8.15 6.32E-17 16.20 1.31 0.49 8.62 2.57E-17 16.59 1.00 0.35 127 APPENDIX E Distil led Water with Greenhouse grown crystals For all tests, sample volume = 1.5 L, crystal mass = 1.5 g, stirrer speed = 70 rpm, temp = 15°C pH adjusted with HC1 and N a O H 24 Hour Reaction PH Mg Ca K P04-P Mg Ca K P04-P mg/L mg/L mg/L mg/L mol/L mol/L mol/L mol/L 6.25 5.677 79.39 0.483 28.015 2.34E-04 1.98E-03 1.24E-05 9.05E-04 6.97 4.586 37.67 0.3973 13.136 1.89E-04 9.40E-04 1.02E-05 4.24E-04 7.28 3.768 23.2 0.752 8.65 1.55E-04 5.79E-04 1.92E-05 2.79E-04 7.65 2.622 13.5 0.5073 6.171 1.08E-04 3.37E-04 1.30E-05 1.99E-04 7.85 2.257 10.94 0.5092 6.38 9.29E-05 2.73E-04 1.30E-05 2.06E-04 8.28 1.549 7.824 0.4822 6.631 6.37E-05 1.95E-04 1.23E-05 2.14E-04 6.47 5.989 77.4 1.059 25.999 2.46E-04 1.93E-03 2.71 E-05 8.39E-04 7.06 4.704 36.02 0.1392 12.052 1.94E-04 8.99E-04 3.56E-06 3.89E-04 7.34 3.845 21.41 0.25 8.919 1.58E-04 5.34E-04 6.39E-06 2.88E-04 7.66 2.648 13.73 0.5345 7.033 1.09E-04 3.43E-04 1.37E-05 2.27E-04 7.78 2.494 12.38 0.4684 6.851 1.03E-04 3.09E-04 1.20E-05 2.21 E-04 7.98 1.93 10.01 0.568 6.53 7.94E-05 2.50E-04 1.45E-05 2.11 E-04 6.68 5.249 63.96 1.026 25.802 2.16E-04 1.60E-03 2.62E-05 8.33E-04 7.74 3.965 32.48 0.764 13.113 1.63E-04 8.10E-04 1.95E-05 4.23E-04 7.87 3.5 23.68 0.6405 10.115 1.44E-04 5.91 E-04 1.64E-05 3.27E-04 7.73 2.472 13.11 0.5389 6.584 1.02E-04 3.27E-04 1.38E-05 2.13E-04 7.76 2.334 12.27 0.5484 6.816 9.60E-05 3.06E-04 1.40E-05 2.20E-04 8.08 1.758 9.515 0.6041 6.775 7.23E-05 2.37E-04 1.55E-05 2.19E-04 7.11 4.657 50.2 0.7961 19.501 1.92E-04 1.25E-03 2.04E-05 6.30E-04 7.87 3.585 26.38 0.7864 10.893 1.48E-04 6.58E-04 2.01 E-05 3.52E-04 8.05 3.049 17.63 0.4318 9.203 1.25E-04 4.40E-04 1.10E-05 2.97E-04 7.91 20.22 11.49 0.2425 7.03 8.32E-04 2.87E-04 6.20E-06 2.27E-04 8 2.076 11.04 0.2943 6.891 8.54E-05 2.75E-04 7.53E-06 2.23E-04 8.44 1.433 8.341 0.7682 6.21 5.90E-05 2.08E-04 1.96E-05 2.01 E-04 128 A P P E N D I X E Ca:P Mg:P PH Mixture Mixture Molar Molar Ps pPs Ratio Ratio 6.25 5.17E-15 14.29 2.19 0.26 6.97 7.64E-16 15.12 2.22 0.44 7.28 4.82E-16 15.32 2.07 0.56 7.65 9.39E-17 16.03 1.69 0.54 7.85 6.8E-17 16.17 1.33 0.45 8.28 3.29E-17 16.48 0.91 0.30 6.47 1.08E-14 13.97 2.30 0.29 7.06 2.41 E-16 15.62 2.31 0.50 7.34 1.56E-16 15.81 1.85 0.55 7.66 1.16E-16 15.94 1.51 0.48 7.78 8.4E-17 16.08 1.40 0.46 7.98 6.07E-17 16.22 1.18 0.38 6.68 7.53E-15 14.12 1.92 0.26 7.74 1.09E-15 14.96 1.91 0.39 7.87 4.55E-16 15.34 1.81 0.44 7.73 9.75E-17 16.01 1.54 0.48 7.76 9.08E-17 16.04 1.39 0.44 8.08 5.8E-17 16.24 1.09 0.33 7.11 3.08E-15 14.51 1.99 0.30 7.87 6.87E-16 15.16 1.87 0.42 8.05 1.81E-16 15.74 1.48 0.42 7.91 3.36E-16 15.47 1.26 3.66 8 3.94E-17 16.40 1.24 0.38 8.44 4.83E-17 16.32 1.04 0.29 129 APPENDIX E Greenhouse Wastewater with Greenhouse grown crystals For all tests, sample volume = 1.5 L , crystal mass = 1.5 g, stirrer speed = 70 rpm, temp = 25°C pH adjusted with HC1 and NaOH 24 Hour Reaction PH Mg Ca K P04-P Mg Ca K PQ4-P mg/L mg/L mg/L mg/L mol/L mol/L mol/L mol/L 5.32 92.21 517.2 415.3 99.915 3.79E-03 1 29E-02 1 .06E-02 3 23E-03 5.67 90.83 466.3 410.3 82.718 3.74E-03 1 16E-02 1 .05E-02 2 67E-03 5.94 92.28 444.9 413.3 73.699 3.80E-03 1 11E-02 1 .06E-02 2 38E-03 6.31 90.94 417 404.6 64.962 3.74E-03 1 04E-02 1 .03E-02 2 10E-03 6.96 87.01 341.8 424.6 23.93 3.58E-03 8 53E-03 1 .09E-02 7 73E-04 7.37 82.74 303.4 400.5 10.501 3.40E-03 7 57E-03 1 .02E-02 3 39E-04 5.87 87.01 368.8 401.1 45.929 3.58E-03 9 20E-03 1 .03E-02 1 48E-03 6.35 89.18 331.9 432 16.948 3.67E-03 8 28E-03 1 .10E-02 5 47E-04 7.15 82.53 323.3 412.7 13.521 3.40E-03 8 07E-03 1 .06E-02 4 37E-04 7.3 84.11 320.3 413.2 12.954 3.46E-03 7 99E-03 1 .06E-02 4 18E-04 7.49 83.81 308.5 413.1 6.877 3.45E-03 7 70E-03 1 .06E-02 2 22E-04 7.87 83.07 294 424.3 4.27 3.42E-03 7 34E-03 1 .09E-02 1 38E-04 6.37 87.44 314.8 419.2 13.011 3.60E-03 7 85E-03 1 .07E-02 4 20E-04 6.95 83.47 282.4 401 4.102 3.43E-03 7 05E-03 1 .03E-02 1 32E-04 7.56 80.85 305.5 410.3 5.366 3.33E-03 7 62E-03 1 .05E-02 1 73E-04 7.79 79.43 293.8 400.4 3.485 3.27E-03 7 33E-03 1 .02E-02 1 13E-04 8.39 79.75 275.7 407.7 1.272 3.28E-03 6 88E-03 1 .04E-02 4 11 E-05 8.58 78.22 263.8 403 0.902 3.22E-03 6 58E-03 1 .03E-02 2 91 E-05 130 A P P E N D I X E Ca:P Mg:P pH Mixture Mixture Molar Molar Ps pPs Ratio Ratio 5.32 1.68E-09 8.78 4.00 1.18 5.67 1.22E-09 8.91 4.36 1.40 5.94 1.06E-09 8.97 4.66 1.60 6.31 8.45E-10 9.07 4.96 1.78 6.96 2.56E-10 9.59 11.04 4.63 7.37 8.95E-11 10.05 22.33 10.04 5.87 5.01 E-10 9.30 6.20 2.41 6.35 1.84E-10 9.74 15.13 6.70 7.15 1.26E-10 9.90 18.48 7.78 7.3 1.22E-10 9.91 19.11 8.27 7.49 6.23E-11 10.21 34.67 15.53 7.87 3.75E-11 10.43 53.21 24.79 6.37 1.27E-10 9.90 18.70 8.56 6.95 3.29E-11 10.48 53.20 25.93 7.56 4.61 E-11 10.34 43.99 19.20 7.79 2.76E-11 10.56 65.15 29.04 8.39 9.67E-12 11.01 167.49 79.89 8.58 6.36E-12 11.20 226.00 110.50 131 APPENDIX F APPENDIX F DATA FOR REACTOR OPERATION 132 A P P E N D I X F Feed In-Reactor P04 Mg Ca K P04 Mg Ca K Date PH mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L 6-Dec-01 8.00 38.65 58.26 305.5 168.9 37.52 57.53 291.9 164.5 10-Dec-01 8.60 40.78 58.31 304 166.6 27.91 56.3 285.3 163.3 12-Deo01 8.00 56.19 58.26 304.4 168.2 32.50 58.29 290.2 165.4 14-Dec-01 8.30 40.95 59.18 311.3 169.3 29.55 57.97 292.4 165.8 17-Dec-01 7.80 42.10 57.61 304.4 167.4 38.06 57.16 303.7 166 19-Dec-01 8.60 41.32 57.79 301.6 165.6 18.06 56.53 281.3 163.7 4-Jan-02 8.60 41.56 57.9 308.9 168 11.83 55.4 272.9 164.5 7-Jan-02 8.00 51.00 57.45 305.3 165 34.91 56.05 287.6 165.3 9-Jan-02 8.00 40.22 57.15 307.4 164.5 29.20 56.14 291.5 163.1 11-Jan-02 8.60 40.88 58.12 311 168.1 14.39 54.87 277.1 161.7 14-Jan-02 8.70 46.28 57.19 305.3 165.7 12.53 53.79 269.4 161.7 16-Jan-02 8.60 49.34 57.43 306 165.3 17.98 53.98 277.8 155.5 18-Jan-02 8.10 40.38 57.4 309.6 166.6 22.86 53.8 279.3 157.4 21-Jan-02 9.00 48.28 57.66 306.3 167.1 9.93 53.19 161.4 158.1 23-Jan-02 7.70 51.51 57.59 309.6 167:3 40.75 54.48 289.2 160.7 25-Jan-02 8.40 50.24 57.71 307.5 167.5 24.84 53.89 276.9 157.3 28-Jan-02 8.20 39.08 56.68 301.7 164.6 24.77 53.79 283.9 158.4 31-Jan-02 8.40 60.97 57.23 311.3 163 32.58 54.58 284.9 158.9 1-Feb-02 8.2 50.45 57.32 308 167.1 25.79 53.13 281 158.3 4-Feb-02 8.5 40.67 56.55 304.1 161.1 22.56 54.96 287.2 160.2 6-Feb-02 8 43.21 62.6 293.1 177 26.72 60.61 274 170.8 8-Feb-02 8.3 40.41 62.37 288.3 173 22.55 59.4 260.7 167.1 11-Fer>02 7.3 41.16 61.27 288.6 170.9 45.73 61.25 290.5 171.8 13-Feb-02 8 40.73 62.01 288.1 173.5 30.88 59.32 275.1 168.7 1-Apr-02 7.1 193.88 150.1 460.8 213.1 84.90 132.5 258.6 192.7 5-Apr-02 7.2 191.80 160.3 492 183.7 98.56 151.6 407.9 174.6 8-Apr-02 8.6 173.52 163.4 476.5 185.7 27.58 137.6 327.5 163.8 10-Apr-02 8.2 156.82 158.7 469.1 184.7 35.74 141.2 360.8 172.9 12-Apr-02 7.9 141.19 155.7 466.7 181.6 51.02 141.3 374.7 172 15-Apr-02 7.8 147.12 140 453.7 184.2 85.72 131.5 397.9 173.7 17-Apr-02 7.8 160.30 141.1 467.5 180.9 83.71 129 390.3 211.2 25-Apr-02 7.3 216.13 128.3 489.7 279.8 84.34 124.1 427.6 268.9 29-Apr-02 7.9 203.78 118.4 491.3 294.7 85.82 116.4 417 282.1 2-May-02 7.5 190.34 112.3 507.3 282.7 100.19 110.7 447.5 277.4 6-May-02 7.4 179.14 110.1 506.8 279 81.43 106.9 431.4 274.4 13-May-02 7 213.33 104.7 530.9 352.4 99.36 99.78 438.1 328.5 23-May-02 7.3 219.67 99.44 467.3 388.9 49.82 100.9 307.8 345.9 133 APPENDIX F Effluent P04 Mg Ca K P04 Date mg/L mg/L mg/L mg/L % 6-Dec-01 26.57 56.73 281.6 163.3 31.26 10-Dec-01 14.02 55.37 269.4 162.4 65.63 12-Dec-01 24.97 57.58 292.2 167.3 55.57 14-Dec-01 21.74 57.15 284.5 165.9 46.92 17-Dec-01 36.32 56.31 292.8 160 13.71 19-Dec-01 7.74 56.12 272.6 163.4 81.27 4-Jan-02 7.78 54.19 266.9 160 81.27 7-Jan-02 15.95 54.41 277 161.1 68.72 9-Jan-02 17.57 56.49 285 154.9 56.33 11-Jan-02 6.39 52.01 255.1 155.7 84.38 14-Jan-02 5.81 51.88 252.1 153.6 87.45 16-Jan-02 9.97 52.3 259 155.5 79.80 18-Jan-02 15.99 52.7 263.8 141.3 60.39 21-Jan-02 3.59 52.85 250.8 156.7 92.57 23-Jan-02 31.24 53.87 284.2 159.3 39.36 25-Jan-02 11.25 52.06 260.9 154.1 77.61 28-Jan-02 20.01 53.09 265 149.8 48.78 31-Jan-02 12.41 53.3 270.5 157.9 79.65 1-Feb-02 14.27 52.07 264.9 152.6 71.72 4-Feb-02 9.49 53.44 267.6 156.6 76.67 6-Feb-02 17.73 58.9 257.1 166.3 58.96 8-Feb-02 8.70 57.48 248.2 165.2 78.47 11-Feb-02 33.98 60.02 277.3 168.9 17.44 13-Feb-02 26.53 58.29 264.8 166.9 34.87 1-Apr-02 134.68 139.7 412.4 198.3 30.53 5-Apr-02 110.77 147.7 405.4 169.6 42.25 8-Apr-02 8.40 132.8 307 157.8 95.16 10-Apr-02 21.58 140.4 347.9 171.8 86.24 12-Apr-02 31.69 137.7 357.6 164.4 77.55 15-Apr-02 56.71 126.6 369.8 169.2 61.45 17-Apr-02 61.77 125 363.4 210.9 61.47 25-Apr-02 70.88 118.9 412.9 267.3 67.20 29-Apr-02 51.26 109.5 389.4 276.2 74.85 2-May-02 66.04 103.6 395.9 281.1 65.30 6-May-02 43.10 98.97 394.3 265.6 75.94 13-May-02 68.12 96.81 396.3 322.4 68.07 23-May-02 48.83 82.42 295.2 339.2 77.77 Removal Efficiency Mg Ca K % % % 2.63 7.82 3.32 5.04 11.38 2.52 1.17 4.01 0.54 3.43 8.61 2.01 2.26 3.81 4.42 2.89 9.62 1.33 6.41 13.60 4.76 5.29 9.27 2.36 1.15 7.29 5.84 10.51 17.97 7.38 9.28 17.43 7.30 8.93 15.36 5.93 8.19 14.79 15.19 8.34 18.12 6.22 6.46 8.20 4.78 9.79 15.15 8.00 6.33 12.16 8.99 6.87 13.11 3.13 9.16 13.99 8.68 5.50 12.00 2.79 5.91 12.28 6.05 7.84 13.91 4.51 2.04 3.92 1.17 6.00 8.09 3.80 6.93 10.50 6.95 7.86 17.60 7.68 18.73 35.57 15.02 11.53 25.84 6.98 11.56 23.38 9.47 9.57 18.49 8.14 11.41 22.27 -16.58 7.33 15.68 4.47 7.52 20.74 6.28 7.75 21.96 0.57 10.11 22.20 4.80 7.54 25.35 8.51 17.12 36.83 12.78 134 APPENDIX F Feed Recycle Total Flow Flow Flow P04-P Date mL/min mL/min mL/min mol/L 6-Dec-01 730 2100 2830 1.25E-03 10-Dec-01 445 200 645 1.32E-03 12-Dec-01 475 1855 2330 1.81E-03 14-Dec-01 480 2320 2800 1.32E-03 17-Dec-01 520 1730 2250 1.36E-03 19-Decr01 460 2140 2600 1.33E-03 4-Jan-02 480 2000 2480 1.34E-03 7-Jan-02 430 2170 2600 1.65E-03 9-Jan-02 460 2240 2700 1.30E-03 11-Jan-02 500 1820 2320 1.32E-03 14-Jan-02 450 1900 2350 1.49E-03 16-Jan-02 480 1340 1820 1.59E-03 18-Jan-02 450 1370 1820 1.30E-03 21-Jan-02 460 1640 2100 1.56E-03 23-Jan-02 510 1820 2330 1.66E-03 25-Jan-02 510 1240 1750 1.62E-03 28-Jan-02 490 960 1450 1.26E-03 31-Jan-02 480 1140 1620 1.97E-03 1-Feb-02 480 940 1420 1.63E-03 4-Feb-02 470 950 1420 1.31 E-03 6-Feb-02 440 960 1400 1.40E-03 8-Feb-02 460 1100 1560 1.30E-03 11-Feb-02 540 200 740 1.33E-03 13-Feb-02 450 970 1420 1.32E-03 1-Apr-02 450 3550 4000 6.26E-03 5-Apr-02 520 3800 4320 6.19E-03 8-Apr-02 270 3100 3370 5.60E-03 10-Apr-02 580 2900 3480 5.06E-03 12-Apr-02 450 3100 3550 4.56E-03 15-Apr-02 390 2910 3300 4.75E-03 17-Apr-02 420 2960 3380 5.18E-03 25-Apr-02 360 1440 1800 6.98E-03 29-Apr-02 420 880 1300 6.58E-03 2-May-02 420 750 1170 6.15E-03 6-May-02 420 1400 1820 5.78E-03 13-May-02 660 1440 2100 6.89E-03 23-May-02 250 1200 1450 7.09E-03 Feed Mg Ca mol/L mol/L 2.40E-03 7.62E-03 2.40E-03 7.58E-03 2.40E-03 7.59E-03 2.44E-03 7.77E-03 2.37E-03 7.59E-03 2.38E-03 7.52E-03 2.38E-03 7.71 E-03 2.36E-03 7.62E-03 2.35E-03 7.67E-03 2.39E-03 7.76E-03 2.35E-03 7.62E-03 2.36E-03 7.63E-03 2.36E-03 7.72E-03 2.37E-03 7.64E-03 2.37E-03 7.72E-03 2.37E-03 7.67E-03 2.33E-03 7.53E-03 2.36E-03 7.77E-03 2.36E-03 7.68E-03 2.33E-03 7.59E-03 2.58E-03 7.31 E-03 2.57E-03 7.19E-03 2.52E-03 7.20E-03 2.55E-03 7.19E-03 6.18E-03 1.15E-02 6.60E-03 1.23E-02 6.72E-03 1.19E-02 6.53E-03 1.17E-02 6.41 E-03 1.16E-02 5.76E-03 1.13E-02 5.81 E-03 1.17E-02 5.28E-03 1.22E-02 4.87E-03 1.23E-02 4.62E-03 1.27E-02 4.53E-03 1.26E-02 4.31 E-03 1.32E-02 4.09E-03 1.17E-02 K Ca/Mg mol/L molar ratio 4.32E-03 3.18 4.26E-03 3.1.6 4.30E-03 3.17 4.33E-03 3.19 4.28E-03 3.20 4.24E-03 3.16 4.30E-03 3.23 4.22E-03 3.22 4.21 E-03 3.26 4.30E-03 3.24 4.24E-03 3.24 4.23E-03 3.23 4.26E-03 3.27 4.27E-03 3.22 4.28E-03 3.26 4.28E-03 3.23 4.21 E-03 3.23 4.17E-03 3.30 4.27E-03 3.26 4.12E-03 3.26 4.53E-03 2.84 4.42E-03 2.80 4.37E-03 2.86 4.44E-03 2.82 5.45E-03 1.86 4.70E-03 1.86 4.75E-03 1.77 4.72E-03 1.79 4.64E-03 1.82 4.71 E-03 1.96 4.63E-03 2.01 7.16E-03 2.31 7.54E-03 2.52 7.23E-03 2.74 7.14E-03 2.79 9.01 E-03 3.07 9.95E-03 2.85 135 Date P04-P mol/L In-Reactor Condition Mg Ca K Ca/Mg mol/L mol/L mol/L molar ratio 6-Dec-01 1.21E-03 2.37E-03 7.28E-03 4.21 E-03 3.08 10-Dec-01 9.01 E-04 2.32E-03 7.12E-03 4.18E-03 3.07 12-Dec-01 1.05E-03 2.40E-03 7.24E-03 4.23E-03 3.02 14-Dec-01 9.54E-04 2.39E-03 7.30E-03 4.24E-03 3.06 17-Dec-01 1.23E-03 2.35E-03 7.58E-03 4.25E-03 3.22 19-Dec-01 5.83E-04 2.33E-03 7.02E-03 4.19E-03 3.02 4-Jan-02 3.82E-04 2.28E-03 6.81 E-03 4.21 E-03 2.99 7-Jan-02 1.13E-03 2.31 E-03 7.18E-03 4.23E-03 3.11 9-Jan-02 9.43E-04 2.31 E-03 7.27E-03 4.17E-03 3.15 11-Jan-02 4.65E-04 2.26E-03 6.91 E-03 4.14E-03 3.06 14-Jan-02 4.05E-04 2.21 E-03 6.72E-03 4.14E-03 3.04 16-Jan-02 5.81 E-04 2.22E-03 6.93E-03 3.98E-03 3.12 18-Jan-02 7.38E-04 2.21 E-03 6.97E-03 4.03E-03 3.15 21-Jan-02 3.21 E-04 2.19E-03 4.03E-03 4.04E-03 1.84 23-Jan-02 1.32E-03 2.24E-03 7.22E-03 4.11 E-03 3.22 25-Jan-02 8.02E-04 2.22E-03 6.91 E-03 4.02E-03 3.12 28-Jan-02 8.00E-04 2.21 E-03 7.08E-03 4.05E-03 3.20 31-Jan-02 1.05E-03 2.25E-03 7.11 E-03 4.06E-03 3.16 1-Feb-02 8.33E-04 2.19E.03 7.01 E-03 4.05E-03 3.21 4-Feb-02 7.29E-04 2.26E-03 7.17E-03 4.10E-03 3.17 6-Feb-02 8.63E-04 2.49E-03 6.84E-03 4.37E-03 2.74 8-Feb-02 7.28E-04 2.44E-03 6.50E-03 4.27E-03 2.66 11-Feb-02 1.48E-03 2.52E-03 7.25E-03 4.39E-03 2.88 13-Feb-02 9.97E-04 2.44E-03 6.86E-03 4.31 E-03 2.81 1-Apr-02 2.74E-03 5.45E-03 6.45E-03 4 93E-03 1.18 5-Apr-02 3.18E-03 6.24E-03 1.02E-02 4 47E-03 1.63 8-Apr-02 8.90E-04 5.66E-03 8.17E-03 4 19E-03 1.44 10-Apr-02 1.15E-03 5.81 E-03 9.00E-03 4 42E-03 1.55 12-Apr-02 1.65E-03 5.81 E-03 9.35E-03 4 40E-03 1.61 15-Apr-02 2.77E-03 5.41 E-03 9.93E-03 4 44E-03 1.83 17-Apr-02 2.70E-03 5.31 E-03 9.74E-03 5 40E-03 1.83 25-Apr-02 2.72E-03 5.11 E-03 1.07E-02 6 88E-03 2.09 29-Apr-02 2.77E-03 4.79E-03 1.04E-02 7 21 E-03 2.17 2-May-02 3.24E-03 4.56E-03 1.12E-02 7 09E-03 2.45 6-May-02 2.63E-03 4.40E-03 1.08E-02 7 02E-03 2.45 13-May-02 3.21 E-03 4.11 E-03 1.09E-02 8 40E-03 2.66 23-May-02 1.61 E-03 4.15E-03 7.68E-03 8 85E-03 1.85 APPENDIX F Effluent P04-P Mg Ca. K Date rhol/L mol/L mol/L mol/L 6-Dec-01 8.58E-04 2.33E-03 7.03E-03 4.18E-03 10-Dec-01 4.53E-04 2.28E-03 6.72E-03 4.15E-03 12-Dec-01 8.06E-04 2.37E-03 7.29E-03 4.28E-03 14-Dec-01 7.02E-04 2.35E-03 7.10E-03 4.24E-03 17-Dec-01 1.17E-03 2.32E-03 7.31 E-03 4.09E-03 19-Dec-01 2.50E-04 2.31 E-03 6.80E-03 4.18E-03 4-Jan-02 2.51 E-04 2.23E-03 6.66E-03 4.09E-03 7-Jan-02 5.15E-04 2.24E-03 6.91 E-03 4.12E-03 9-Jan-02 5.67E-04 2.32E-03 7.11 E-03 3.96E-03 11-Jan-02 2.06E-04 2.14E-03 6.36E-03 3.98E-03 14-Jan-02 1.88E-04 2.13E-03 6.29E-03 3.93E-03 16-Jan-02 3.22E-04 2.15E-03 6.46E-03 3.98E-03 18-Jan-02 5.16E-04 2.17E-03 6.58E-03 3.61 E-03 21-Jan-02 1.16E-04 2.17E-03 6.26E-03 4.01 E-03 23-Jan-02 1.01 E-03 2.22E-03 7.09E-03 4.07E-03 25-Jan-02 3.63E-04 2.14E-03 6.51 E-03 3.94E-03 28-Jan-02 6.46E-04 2.18E-03 6.61 E-03 3.83E-03 31-Jan-02 4.01 E-04 2.19E-03 6.75E-03 4.04E-03 1-Feb-02 4.61 E-04 2.14E-03 6.61 E-03 3.90E-03 4-Feb-02 3.06E-04 2.20E-03 6.68E-03 4.01 E-03 6-Feb-02 5.73E-04 2.42E-03 6.41 E-03 4.25E-03 8-Feb-02 2.81 E-04 2.37E-03 6.19E-03 4.23E-03 11-Feb-02 1.10E-03 2.47E-03 6.92E-03 4.32E-03 13-Feb-02 8.57E-04 2.40E-03 6.61 E-03 4.27E-03 1-Apr-02 4.35E-03 5.75E-03 1.03E-02 5.07E-03 5-Apr-02 3.58E-03 6.08E-03 1.01E-02 4.34E-03 8-Apr-02 2.71 E-04 5.47E-03 7.66E-03 4.04E-03 10-Apr-02 6.97E-04 5.78E-03 8.68E-03 4.39E-03 12-Apr-02 1.02E-03 5.67E-03 8.92E-03 4.20E-03 15-Apr-02 1.83E-03 5.21 E-03 9.23E-03 4.33E-03 17-Apr-02 1.99E-03 5.14E-03 9.07E-03 5.39E-03 25-Apr-02 2.29E-03 4.89E-03 1.03E-02 6.84E-03 29-Apr-02 1.66E-03 4.51 E-03 9.72E-03 7.06E-03 2-May-02 2.13E-03 4.26E-03 9.88E-03 7.19E-03 6-May-02 1.39E-03 4.07E-03 9.84E-03 6.79E-03 13-May-02 2.20E-03 3.98E-03 9.89E-03 8.25E-03 23-May-02 1.58E-03 3.39E-03 7.37E-03 8.68E-03 137 A P P E N D I X F Molar Removal (In-Reactorto Effluent) P04-P Mg Ca K Ca/P Mg/P K/P Date mol/L mol/L mol/L mol/L molar ratio molar ratiomolar ral 6-Dec-01 3.54E-04 3.29E-05 2.57E-04 3.07E-05 0.73 0.09 0.09 10-Dec-01 4.49E-04 3.83E-05 3.97E-04 2.30E-05 0.88 0.09 0.05 12-Dec-01 2.43E-04 2.92E-05 -4.99E-05 -4.86E-05 -0.21 0.12 -0.20 14-Dec-01 2.52E-04 3.37E-05 1.97E-04 -2.56E-06 0.78 0.13 -0.01 17-Dec-01 5.60E-05 3.50E-05 2.72E-04 1.53E-04 4.86 0.62 2.74 19-Der>01 3.33E-04 1.69E-05 2.17E-04 7.67E-06 0.65 0.05 0.02 4-Jan-02 1.31 E-04 4.98E-05 1.50E-04 1.15E-04 1.15 0.38 0.88 7-Jan-02 6.12E-04 6.75E-05 2.64E-04 1.07E-04 0.43 0.11 0.18 9-Jan-02 3.76E-04 -1.44E-05 1.62E-04 2.10E-04 0.43 -0.04 0.56 11-Jan-02 2.59E-04 1.18E-04 5.49E-04 1.53E-04 2.12 0.46 0.59 14-Jan-02 2.17E-04 7.86E-05 4.32E-04 2.07E-04 1.99 0.36 0.95 16-Jan-02 2.59E-04 6.91 E-05 4.69E-04 0.00E+00 1.81 0.27 0.00 18-Jan-02 2.22E-04 4.53E-05 3.87E-04 4.12E-04 1.75 0.20 1.86 21-Jan-02 2.05E-04 1.40E-05 -2.23E-03 3.58E-05 -10.88 0.07 0.17 23-Jan-02 3.07E-04 2.51 E-05 1.25E-04 3.58E-05 0.41 0.08 0.12 25-Jan-02 4.39E-04 7.53E-05 3.99E-04 8.18E-05 0.91 0.17 0.19 28-Jan-02 1.54E-04 2.88E-05 4.72E-04 2.20E-04 3.07 0.19 1.43 31-Jan-02 6.51 E-04 5.27E-05 3.59E-04 2.56E-05 0.55 0.08 0.04 1-Feb-02 3.72E-04 4.36E-05 4.02E-04 1.46E-04 1.08 0.12 0.39 4-Feb-02 4.22E-04 6.26E-05 4.89E-04 9.21 E-05 1.16 0.15 0.22 6-Feb-02 2.90E-04 7.04E-05 4.22E-04 1.15E-04 1.45 0.24 0.40 8-Feb-02 4.47E-04 7.90E-05 3.12E-04 4.86E-05 0.70 0.18 0.11 11-Feb-02 3.79E-04 5.06E-05 3.29E-04 7.42E-05 0.87 0.13 0.20 13-Feb-02 1.40E-04 4.24E-05 2.57E-04 4.60E-05 1.83 0.30 0.33 1-Apr-02 -1.61 E-03 -2.96E-04 -3.84E-03 -1.43E-04 2.39 0.18 0.09 5-Apr-02 -3.94E-04 1.60E-04 6.24E-05 1.28E-04 -0.16 -0.41 -0.32 8-Apr-02 6.19E-04 1.98E-04 5.11 E-04 1.53E-04 0.83 0.32 0.25 10-Apr-02 4.57E-04 3.29E-05 3.22E-04 2.81 E-05 0.70 0.07 0.06 12-Apr-02 6.24E-04 1.48E-04 4.27E-04 1.94E-04 0.68 0.24 0.31 15-Apr-02 9.37E-04 2.02E-04 7.01 E-04 1.15E-04 0.75 0.22 0.12 17-Apr-02 7.08E-04 1.65E-04 6.71 E-04 7.67E-06 0.95 0.23 0.01 25-Apr-02 4.34E-04 2.14E-04 3.67E-04 4.09E-05 0.84 0.49 0.09 29-Apr-02 1.12E-03 2.84E-04 6.89E-04 1.51 E-04 0.62 0.25 0.14 2-May-02 1.10E-03 2.92E-04 1.29E-03 -9.46E-05 1.17 0.26 -0.09 6-May-02 1.24E-03 3.26E-04 9.26E-04 2.25E-04 0.75 0.26 0.18 13-May-02 1.01 E-03 1.22E-04 1.04E-03 1.56E-04 1.03 0.12 0.15 23-May-02 3.20E-05 7.60E-04 3.14E-04 1.71 E-04 138 A P P E N D I X F Date Influent In-Reactor Effluent Equilibrium Influent In-Reactor Effluent Ps Ps Ps Ps S.S.Ratio S.S.Ratio S.S.Ratio 6-Dec-01 9.85E-11 8.79E-11 5.88E-11 2.3728E-11 4.15 3.70 2.48 10-Dec-01 1.02E-10 6.21 E-11 2.88E-11 1.0608E-11 9.63 5.85 2.71 12-Dec-01 1.42E-10 7.71 E-11 5.96E-11 2.3728E-11 5.99 3.25 2.51 14-Dec-01 1.08E-10 7.04E-11 4.97E-11 1.575E-11 6.88 4.47 3.16 17-Dec-01 1.05E-10 9.30E-11 8.12E-11 3.1453E-11 3.33 2.96 2.58 19-Dec-01 1.01 E-10 3.99E-11 1.64E-11 1.0608E-11 9.53 3.76 1.55 4-Jan-02 1.06E-10 2.49E-11 1.53E-11 1.0608E-11 9.98 2.35 1.44 7-Jan-02 1.25E-10 7.89E-11 3.28E-11 2.3728E-11 5.27 3.32 1.38 9-Jan-02 9.86E-11 6.61 E-11 3.71 E-11 2.3728E-11 4.15 2.79 1.57 11-Jan-02 1.05E-10 3.00E-11 1.12E-11 1.0608E-11 9.93 2.83 1.05 14-Jan-02 1.14E-10 2.49E-11 9.89E-12 9.3268E-12 12.17 2.67 1.06 16-Jan-02 1.22E-10 3.56E-11 1.78E-11 1.0608E-11 11.46 3.35 1.68 18-Jan-02 1.01E-10 4.58E-11 2.66E-11 2.0663E-11 4.91 2.22 1.29 21-Jan-02 1.21E-10 1.14E-11 6.31E-12 6.3949E-12 18.89 1.79 0.99 23-Jan-02 1.30E-10 8.75E-11 6.46E-11 3.6311 E-11 3.59 2.41 1.78 25-Jan-02 1.27E-10 4.94E-11 2.00E-11 1.3784E-11 9.19 3.59 1.45 28-Jan-02 9.33E-11 5.08E-11 3.58E-11 1.8025E-11 5.17 2.82 1.98 31-Jan-02 1.50E-10 6.83E-11 2.40E-11 1.3784E-11 10.89 4.95 1.74 1-Feb-02 1.26E-10 5.17E-11 2.55E-11 1.8025E-11 7.00 2.87 1.41 4-Feb-02 9.55E-11 4.84E-11 1.80E-11 1.2083E-11 7.91 4.00 1.49 6-Feb-02 1.19E-10 6.43E-11 3.79E-11 2.3728E-11 5.01 2.71 1.60 8-Feb-02 1.07E-10 4.95E-11 1.74E-11 1.575E-11 6.77 3.14 1.10 11-Feb-02 1.05E-10 1.19E-10 8.10E-11 6.5758E-11 1.60 1.80 1.23 13-Feb-02 1.07E-10 7.21 E-11 5.79E-11 2.3728E-11 4.51 3.04 2.44 1-Apr-02 2.42E-09 4.75E-10 1.30E-09 8.9588E-11 27.05 5.31 14.56 5-Apr-02 2.36E-09 9.02E-10 9.54E-10 7.6671 E-11 30.73 11.77 12.44 8-Apr-02 2.13E-09 1.73E-10 4.58E-11 1.0608E-11 200.54 16.27 4.32 10-Apr-02 1.83E-09 2.67E-10 1.54E-10 1.8025E-11 101.43 14.81 8.52 12-Apr-02 1.58E-09 3.94E-10 2.18E-10 2.7294E-11 57.88 14.43 7.97 15-Apr-02 1.46E-09 6.61 E-10 3.81 E-10 3.1453E-11 46.40 21.00 12.11 17-Apr-02 1.62E-09 7.55E-10 5.02E-10 3.1453E-11 51.57 24.00 15.95 25-Apr-02 3.22E-09 1.02E-09 7.89E-10 6.5758E-11 48.99 15.52 11.99 29-Apr-02 2.96E-09 9.96E-10 5.12E-10 2.7294E-11 108.52 36.51 18.75 2-May-02 2.60E-09 1.17E-09 6.46E-10 4.8672E-11 53.40 23.99 13.26 6-May-02 2.36E-09 8.74E-10 3.79E-10 5.6516E-11 41.84 15.46 6.70 13-May-02 3.54E-09 1.21E-09 7.14E-10 1.0491 E-10 33.77 11.53 6.81 23-May-02 3.37E-09 4.54E-10 3.42E-10 6.5758E-11 51.19 6.90 5.20 139 

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