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Investigation of effect of dynamic operational conditions on membrane fouling in a membrane enhanced… Abdullah, Syed Zaki 2007

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INVESTIGATION OF EFFECT OF DYNAMIC OPERATIONAL CONDITIONS ON MEMBRANE FOULING IN A MEMBRANE ENHANCED BIOLOGICAL PHOSPHORUS REMOVAL PROCESS by SYED ZAKI ABDULLAH B.Sc. (Civil Engineering), Bangladesh University of Engineering and Technology, Dhaka, Bangladesh A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF APPLIED SCIENCE in THE FACULTY OF GRADUATE STUDIES (Civil Engineering) THE UNIVERSITY OF BRITISH COLUMBIA November 2007 © Syed Zaki Abdullah, 2007 Abstract The membrane bioreactor (MBR) is becoming increasingly popular for wastewater treatment, mainly due to its capability of producing high quality effluent with a relatively small footprint. However, high plant maintenance and operating costs due to membrane fouling limit the wide spread application of MBRs. Membrane fouling generally depends on the interactions between the membrane and, the activated sludge mixed liquor, which in turn, are affected by the chosen operating conditions. The present research study aimed to explore the process performance and membrane fouling in the membrane enhanced biological phosphorus removal (MEBPR) process under different operating conditions by, (1) comparing two MEBPRs operated in parallel, one with constant inflow and another with a variable inflow, and by, (2) operating the MEBPRs with different solids retention times (SRT). On-line filtration experiments were conducted simultaneously in both MEBPR systems by using test membrane modules. From the transmembrane pressure (TMP) data of the test membrane modules, it was revealed that fouling propensities of the MEBPR mixed liquors were similar in both parallel reactors under the operating conditions applied, although the fouling propensity of the aerobic mixed liquors of both reactors increased when the SRT of the reactors was reduced. Routinely monitored reactor performance data suggest that an MEBPR process with a varying inflow (dynamic operating condition) performs similarly to an MEBPR process with steady operating conditions at SRTs of 10 days and 20 days. Mixed liquor characterization tests were conducted, including critical flux, capillary suction time (CST), time to filter (TTF) and, bound and soluble extracellular polymeric substances (EPS) were quantified, to evaluate their role on membrane fouling. The tests results suggest that the inflow variation in an MEBPR process did not make a significant difference in any of the measured parameters. With decreased SRT, an increase in the concentrations of EPS was observed, especially the bound protein, and the bound and soluble humic-like substances. This suggests ii that these components of activated sludge mixed liquors may be related to membrane fouling. No clear relationship was observed between membrane fouling and other measured parameters, including critical flux, normalized CST and normalized TTF. iii TABLE OF CONTENTS ABSTRACT ^ii TABLE OF CONTENTS iv LIST OF TABLES   viii LIST OF FIGURES   ix LIST OF ABBREVIATIONS   xii ACKNOWLEDGEMENT.   xiv DEDICATION    xv CHAPTER ONE^  1 1.1 PREFACE ^1 1.2 PRESENT PROJECT ^2 CHAPTER TWO ^3 2.1 MEMBRANE BIOREACTORS ^ 3 2.1.1 INTRODUCTION ^3 2.1.2 HISTORY OF MBRS ^3 2.1.3 TYPES OF MBR PROCESSES ^4 2.1.4 ADVANTAGES AND DISADVANTAGES OF MBRS OVER CAS ^4 2.1.5 MEMBRANE APPLICATION IN UBC MEBPR PILOT PLANT ^5 2.2 BASICS OF MEMBRANE FILTRATION PROCESS ^5 2.3 TYPE AND MECHANISM OF MEMBRANE FOULING ^6 2.4 FACTORS INFLUENCING MEMBRANE FOULING ^8 2.4.1 PHYSICAL AND CHEMICAL PARAMETERS OF MEMBRANE ^8 2.4.1.1 Membrane material ^8 2.4.1.2 Membrane pore size and distribution ^9 2.4.1.3 Membrane hydrophobicity and charge ^9 2.4.2 PHYSICO-CHEMICAL AND BIOLOGICAL NATURE OF THE FEED AND MIXED LIQUOR^  10 iv 2.4.2.1 Influent characteristics ^10 2.4.2.2 Mixed liquor parameters ^11 2.4.3 OPERATING CONDITIONS ^16 2.4.3.1 Permeate flux and trans-membrane pressure ^16 2.4.3.2 Aeration and cross flow velocity ^17 2.4.3.3 Solids retention time ^17 2.4.3.4 Transient operating conditions ^18 2.5 MBR FOULING CONTROL ^19 2.5.1 REMOVAL OF FOULING ^19 2.5.2 LIMITATION OF FOULING ^20 2.6 RESEARCH SCOPE AND OBJECTIVES^  20 CHAPTER THREE^  22 3.1 THE UBC WASTEWATER TREATMENT PILOT PLANT^ 22 3.1.1 THE FILTRATION MEMBRANE MODULE ^23 3.2 MODIFICATION OF UBC PILOT PLANT^  26 3.3 EXPERIMENTAL PROGRAM^  27 3.4 ROUTINE MEMBRANE MAINTENANCE^  27 3.4.1 MEMBRANE INTEGRITY TESTING ^27 3.4.2 MEMBRANE CLEANING^  28 3.4.2.1 Operational membrane module ^28 3.4.2.2 Test membrane module ^28 3.5 EFFECTIVE SURFACE AREA OF TEST MEMBRANE MODULE^ 29 3.6 VFA SUPPLEMENTATION^  33 3.7 MAINTAINING DISSOLVED OXYGEN LEVEL^  34 3.8 MAINTAINING SOLIDS RETENTION TIME (SRT)  34 3.9 MONITORING^  35 3.9.1 MONITORING OF REACTOR PERFORMANCE^  35 3.9.2 MONITORING OF FOULING PARAMETERS  35 3.10 SAMPLE HANDLING AND PRESERVATION   36 v 3.11 ANALYTICAL METHODS ^ 37 3.11.1 PERMEATE FLUX MEASUREMENT^  37 3.11.2 TOTAL AND SOLUBLE COD ^37 3.11.3 VOLATILE FATTY ACIDS ^38 3.11.4 AMMONIUM-NITROGEN ^38 3.11.5 TOTAL AND ORTHO-PHOSPHATE PHOSPHORUS ^38 3.11.6 NITRATE-NITRITE ^39 3.11.7 TOTAL KJELDHAL NITROGEN^  39 3.11.8 TOTAL SUSPENDED SOLIDS ^40 3.11.9 CAPILLARY SUCTION TIME ^40 3.11.10 TIME TO FILTER ^40 3.12 EPS EXTRACTION AND QUANTIFICATION^  41 3.13 CRITICAL FLUX TEST^  43 CHAPTER FOUR^  45 4.1 PERFORMANCE OF THE MEBPR TRAINS IN THE UBC PILOT PLANT^  45 4.2 FILTRATION PERFORMANCE OF THE TEST MEMBRANE MODULES IN THE MEBPR TRAINS^  53 4.3 FOULING PROPENSITY OF THE ACTIVATED SLUDGE MIXED LIQUORS ^59 4.3.1 CRITICAL FLUX ^60 4.3.2 CAPILLARY SUCTION TIME^  63 4.3.3 TIME TO FILTER ^65 4.3.4 EXTRACELLULAR POLYMERIC SUBSTANCES^  67 4.3.4.1 Effects of EPS contents and membrane fouling ^67 4.3.4.2 Effect of operating conditions on EPS production ^73 CHAPTER FIVE^  76 vi CHAPTER SIX^  78 REFERENCES^  80 APPENDIX A: UBC WASTEWATER TREATMENT PILOT PLANT^ 90 APPENDIX B: TEST MEMBRANE MODULES ^92 APPENDIX C: AVERAGE DATA OF THE REACTOR PERFORMANCE PARAMETERS^  94 APPENDIX D: MONITORING RECORDS^  97 vii LIST OF TABLES Table 3.1^Specifications and operating limits of the operational membrane module ^ 25 Table 3.2^Specifications and operating limits of the test membrane module^ 26 Table 3.3^Calculated effective surface area of the test membrane modules^ 32 Table 3.4^Number of effective membrane strands and calculated effective surface area of the test membrane modules and their ratio^  33 Table 3.5^Sampling frequency for different analytical parameters  36 Table 3.6^Specifications of the gas chromatograph ^38 Table 4.1 ^ ^Influent and effluent characteristics and overall treatment performance of both of the MEBPR trains (side-C and side-V) at the UBC wastewater treatment pilot plant ^46 Table 4.2^Critical flux values for side-C and side-V for 20 day SRT and 10 day SRT^  62 Table 4.3^Normalized CST values for side-C and side-V for 20 day SRT and 10 day SRT^  65 Table 4.4^Normalized TTF values for side-C and side-V for 20 day SRT and 10 day SRT^  65 Table 4.5^Bound EPS concentrations for side-C and side-V for SRTs of 20 days and 10 days ^69 Table 4.6^Soluble EPS concentrations for side-C and side-V for SRTs of 20 days and 10 days^  73 Table C.1. Operational data for Run SRT20 (Operating day 63 to 183)^ 95 Table C.2. Operational data for Run SRT10 (Operating day 185 to 219) ^96 viii LIST OF FIGURES Figure 3.1 Figure 3.2 Figure 3.3 Figure 3.4 Figure 3.5 Figure 4.1 Figure 4.2 Figure 4.3 Figure 4.4 Figure 4.5 Figure 4.6 Figure 4.7 Figure 4.8 Figure 4.9 Figure 4.10 Figure 4.11 Figure 4.12 Schematic of the UBC wastewater treatment pilot plant^ 24 ZW-10 test membrane module^  29 Condition of the membrane opening inside the header of #1, #2 and #3 test membrane modules^  30 TMP vs. flow graph to calculate effective surface area of ZW-10 membrane modules ^31 Condition inside the header of #1, #2 and #3 TM modules after all experimental test runs^  32 Total suspended solids (TSS) in side-C and side-V trains at UBC wastewater treatment pilot plant ^47 Mixed liquor concentrations in different zones of side-C and side-V trains ^47 Influent and effluent temperatures of side-C and side-V trains^ 48 Total COD and filtered COD of influent and effluent of side-C and side-V trains^  48 Influent and effluent ammonium-nitrogen (NH4-N) concentrations of side-C and side-V trains^  49 Influent and effluent nitrite plus nitrate nitrogen (NOx-N) concentrations of side-C and side-V trains^ 49 Influent and anaerobic zone mixed liquor VFA (as acetic acid) concentrations in side-C and side-V trains^  50 Influent and effluent ortho-P concentrations of side-C and side-V trains^ 50 Operational membrane performance for side-C and side-V trains ^51 The TMP profiles of the TM modules at the UBC pilot plant during the first filtration experiment (FE SRT20a)^  54 The TMP profiles of theTM modules at the UBC pilot plant during the second filtration experiment (FE SRT20b) ^56 The TMP profiles of the TM modules at the UBC pilot plant during the third filtration experiment (FE SRT10a) ^57 ix Figure 4.13 The TMP profiles of the #1 TM module during all three filtration experiments ^58 Figure 4.14 The TMP profiles of the #2 TM module during all three filtration experiments ^58 Figure 4.15 The TMP profiles of the #3 TM module during all three filtration experiments ^59 Figure 4.16 Results of flux-step filtration tests with aerobic mixed liquor of both trains (side-C and side-V) at a 20 day SRT^  60 Figure 4.17 Rate of change of TMP vs. flux for critical flux analysis of data from the flux-step test of aerobic mixed liquor of side-C at 10 day SRT^ 61 Figure 4.18 Critical flux calculation using data from the flux-step test of aerobic mixed liquor from side-C at a 10 day SRT ^62 Figure 4.19 Capillary suction time of aerobic mixed liquor during Run SRT20 and Run SRT10^  64 Figure 4.20 Normalized capillary suction time of aerobic mixed liquor during Run SRT20 and Run SRT10^  64 Figure 4.21 Time to filter of aerobic mixed liquor during Run SRT20 and Run SRT10^  66 Figure 4.22 Normalized time to filter of aerobic mixed liquor during Run SRT20 and Run SRT10^  66 Figure 4.23 Bound carbohydrate concentrations in aerobic mixed liquor during Run SRT20 and Run SRT10^  67 Figure 4.24 Bound protein concentration in aerobic mixed liquor during Run SRT20 and Run SRT10^  68 Figure 4.25 Bound humic-like substances concentration in aerobic mixed liquor during Run SRT20 and Run SRT10^  68 Figure 4.26 Total bound EPS concentration in aerobic mixed liquor during Run SRT20 and Run SRT10^  69 Figure 4.27 Soluble carbohydrate concentration in aerobic mixed liquor during Run SRT20 and Run SRT10^  71 x Figure 4.28 Soluble protein concentration in aerobic mixed liquor during Run SRT20 and Run SRT 10^  71 Figure 4.29 Soluble humic-like substances concentration in aerobic mixed liquor during Run SRT20 and Run SRT10^  72 Figure 4.30 Total soluble EPS concentration in aerobic mixed liquor during Run SRT20 and Run SRT10^  72 Figure 4.31 Concentration of total EPS in aerobic mixed liquor of side-C during Run SRT20 and Run SRT10^  74 Figure 4.32 Concentration of total EPS in aerobic mixed liquor of side-V during Run SRT20 and Run SRT10^  74 Figure 4.33 Total EPS concentration in aerobic mixed liquor during Run SRT20 and Run SRT10^  75 Figure A.1. Figure UBC wastewater treatment pilot plant ^91 Figure B.1. Figure Test membrane modules used at the study^  93 xi LIST OF ABBREVIATIONS ASP^activated sludge processes BNR^biological nutrient removal CAS^conventional activated sludge CEBPR^conventional enhanced biological phosphorus removal process COD^chemical oxygen demand CST^capillary suction time DO^dissolved oxygen EPS^extracellular polymeric substances FID^flame ionization detector F/M^food to microorganism ratio GC^gas chromatograph HRT^hydraulic retention time MBR^membrane bioreactor MEBPR^membrane enhanced biological phosphorus removal MF^micro-filtration MLSS^mixed liquor suspended solids NH4-N^ammonium nitrogen NF^nano-filtration NOR-N^nitrite plus nitrate nitrogen OM^operational membrane PAC^powdered activated carbon PE^polyethylene PO4-P^ortho-phosphate phosphorus RO^reverse osmosis SBR^sequencing batch reactors SRT^solids retention time TKN^total Kjeldhal nitrogen TM^test membrane TMP^trans-membrane pressure TTF^time-to-filter TSS^total suspended solids UBC^University of British Columbia UCT^University of Cape town OF^ultra-filtration VFA^volatile fatty acids ACKNOWLEDGEMENT My greatest gratitude goes to Dr. Eric Hall for his excellent guidance, patience and emotional intelligence which helped me in continuing and finishing the project. Working under his supervision, I learnt to transform complex problems to easily understandable concepts by looking at the problems from different angles. This knowledge will help me in all aspects of my life. I am also thankful to Dr. Pierre R. Bdrube, for his invaluable suggestions and insight, he provided throughout my whole study period. My great gratitude goes to Dr. Thomas Hug for his continuous encouragement and help during the project, as well as in the thesis writing. I want to express my sincere gratitude to Fred Koch who helped me a lot at the UBC Pilot Plant. Without his help it would not have been possible to perform all the project works. Thanks are extended to to Susan Harper and Paula Parkinson for their assistance and help with the analytical work for this project. Special thanks are also due to Bill Leung, Doug Hudniuk, John Wong, Scott Jackson, Harald Schrempp and Doug Smith who were always ready to lend a helping hand. To me it is a great privilege to be a member of Environmental Engineering Group at UBC and I would like to thank past and present members for their collaborations and encouragements. The financial support to the present project from the Natural Sciences and Engineering Research Council of Canada (NSERC), from UBC with a University Graduate Fellowship (UGF), and the technical and financial aid from GE Water & Process Technologies (ZENON Membrane Solutions), Stantec Consulting, and Dayton and Knight Ltd., are also acknowledged. Last but not the least I thank God Almighty for giving me the strength. xiv Dedication To my family members & my friends xv CHAPTER ONE INTRODUCTION 1.1 Preface Membrane bioreactor (MBR) technology refers to the combination of a biological wastewater treatment process by activated sludge technology and solid—liquid separation by membrane filtration technology (Le-Clech et al., 2006). These bioreactors are operated similarly to conventional activated sludge processes (ASP), but solid-liquid separation is completed by means of membrane filtration, so there is no need for a secondary settling tank. In recent years, MBR technology has received keen interest for the treatment and reuse of industrial and municipal wastewaters, as evidenced by the 10.9 % average annual growth rate of the MBR market globally (Jiang, 2007). The current global MBR market has been estimated to value around US$ 216 million and to rise to US$ 363 million by 2010 (Le-Clech et al., 2006). The MBR is becoming increasingly popular for wastewater treatment, mainly due to its capability of producing high quality effluent with a relatively small footprint. In addition, MBR technology has many other advantages over the conventional activated sludge (CAS) system. These include good disinfection capability, higher volumetric loading and ability to handle high mixed liquor concentrations (or low F/M), independent control of suspended solids and hydraulic retention times, which gives better protection against shock loading, and less mixed liquor production (Jingsong et al., 2006). The investment cost of MBRs has become comparable to that of the CAS system, but high plant maintenance and operating cost due to membrane fouling, limit the wide spread application of MBRs (Le-Clech et al., 2006). However, due to the interactions between activated mixed liquor components and the membrane, the MBR filtration performance inevitably decreases with filtration time. This is caused by the deposition of soluble and 1 particulate materials onto and into the membrane and this phenomenon is referred to as membrane fouling (Le-Clech et al., 2006). Membrane fouling generally depends on the interaction between the membrane and the activated mixed liquor, as well as the chosen operating conditions, which makes it a complex phenomenon to understand. Though this major drawback has been under investigation since the early MBRs, unfortunately the limited understanding of membrane fouling still remains one of the most challenging issues facing further MBR development (Yang et al., 2006). 1.2 Present Project A preliminary feasibility study (Geng, 2006) was conducted by the University of British Columbia (UBC) on a membrane coupled activated sludge process at the UBC wastewater treatment pilot plant facility, for removal of phosphorus and nitrogen from municipal wastewater. In the facility, membrane filtration technology was integrated with a conventional enhanced biological phosphorus removal process (CEBPR) and the new integrated process was named "membrane enhanced biological phosphorus removal (MEBPR)" process. Among the various process performance studies undertaken, several studies were conducted to characterize membrane fouling under several steady state operating conditions in the pilot scale MEBPR system. These studies suggested that soluble extracellular polymeric substances (EPS) may be the most significant contributor to membrane fouling (Geng, 2006; Pattanayak, 2007). It has been suggested by several authors that EPS formation and fouling may be most extensive during periods of dynamic operation of MBRs, such as short term changes in organic loading, dissolved oxygen concentration, wastewater temperature, or pH (Cote, P., Zenon Environmental Inc., pers. comm.; Drews et al., 2005; Evenblij et al., 2005; Le-Clech et al., 2006). The impact of such dynamic operating conditions on membrane fouling in an MEBPR is largely unknown. As outlined in Section 2.6, the present study focuses on addressing this current knowledge gap. 2 CHAPTER TWO LITERATURE REVIEW 2.1 Membrane Bioreactors 2.1.1 Introduction The combination of membrane filtration technology and the high rate biological process for wastewater treatment is defined as a membrane bioreactor (MBR). The MBR field has undergone rapid development in the last decade and is becoming an attractive alternative to conventional activated sludge processes for many domestic and industrial applications (Le-Clech et al., 2006). 2.1.2 History of MBRs The concept of the activated sludge process coupled with ultra-filtration membrane technology for biomass separation was introduced by the late 1960s, when commercial scale ultra-filtration (UF) and micro-filtration (MF) membranes had become available (Smith et al., 1969). The original process was developed and commercialized by Dorr-Olivier Inc. In the 1970s, MBR technology first entered the Japanese market, where the technology underwent rapid development (Jiang, 2007). During the early development, side stream MBRs with external membrane modules were the original process configuration. Although MBRs provide a compact treatment system and a superior effluent quality compared to the conventional activated sludge treatment, it was difficult to justify the use of such a process because of the high cost of membranes, the potential rapid loss of membrane performance due to fouling and the high energy cost (Le-Clech et al., 2006). The breakthrough for the MBR came in 1989 with the idea of Yamamoto et al., (1989) to submerge the membranes in the bioreactor, which reduced the high energy cost as discussed in the section below. Since that time, MBR technology has attracted some companies in North America and Japan to develop better membrane materials and system configurations, to make the application of 3 membranes in wastewater treatment more feasible. In 2004, there were more than 2200 MBR installations in operation or under construction world wide and 258 full-scale MBR plants in North America (Yang et al., 2006), which indicates that MBR technology has become a serious alternative to conventional treatment (Roest et al., 2002). 2.1.3 Types of MBR processes According to the location of the membrane filtration unit, an MBR is usually classified in one of the two categories: side stream and submerged. In a side stream MBR (or recirculated MBR), an external membrane filtration unit, separated from the bioreactor, is used (Mallevaille et al., 1996). The activated mixed liquor in the bioreactor is pumped to tubular or flat sheet membrane modules where it flows at high tangential velocities (greater than 2 m/s and often greater than 4 m/s) and high applied trans-membrane pressures (typically 400 kPa). This results in a significant consumption of energy, between 4 and 12 kWh per m3 of water treated (Cote and Thompson, 2000). In a submerged MBR, hollow fiber membrane modules, or hollow sheet modules, are immersed in the aeration tank and permeate is generated by applying suction to the lumen of each membrane. The submerged MBR has gained popularity due to its lower energy consumption, as these membrane modules operate at much lower applied trans-membrane pressure (TMP) than side stream MBRs (Gander et al., 2000). The energy consumption for submerged membrane filtration is less than 1 kWh per m 3 of water treated (Le-Clech et al., 2006). 2.1.4 Advantages and disadvantages of MBRs over CAS One of the major advantages of replacing a conventional settler with a membrane is its capability of producing high quality effluent with a smaller treatment process footprint. In addition the MBR has many other advantages over the conventional activated sludge (CAS) system. These include good disinfection capability, higher volumetric loadings and high mixed liquor concentration (or low F/M), independent control of solids and hydraulic 4 retention times, which offers better protection against shock loading, and less mixed liquor production (Jingsong et al., 2006). Considering these advantages, MBR technology is becoming increasingly popular for wastewater treatment. Due to the development of better membrane materials and system configurations, the investment cost of MBRs is now comparable to CAS systems with secondary clarifiers (Jiang, 2007). However, the high operating cost associated with the high energy demand and membrane replacement, is still a controlling factor for MBRs (Judd, 2006). 2.1.5 Membrane application in UBC MEBPR pilot plant MBR technology for wastewater treatment typically has been coupled to the conventional activated sludge process (Monti, 2006). In addition, membrane filtration technology has also been coupled to sequencing batch reactors (SBRs) (Ersu, 2006), biological nutrient removal (BNR) systems, and an anaerobic digestion system, for different wastewater treatment purposes. A membrane enhanced biological phosphorus removal (MEBPR) process, which is installed at the UBC pilot plant is one of the first attempts worldwide to integrate membrane technology with the University of Cape town (UCT)-type biological phosphorus removal process in order to achieve a superior quality effluent (Geng, 2006). The UBC wastewater treatment pilot facility is described in Section 3.1 of this thesis. The present research study was conducted at that pilot plant facility. 2.2 Basics of Membrane Filtration Process Membrane filtration is a physical process for the separation of a mixture of substances with a selective thin film. In pressure-driven membrane processes, which have been widely applied in water and wastewater treatment systems, material that is smaller than the membrane pores is transported across the membrane by the pressure driving force, while material that is larger than the membrane pores is retained at the surface of the membrane. Based on decreasing pore size (or molecular weight cut-off), membranes are generally 5 classified as micro-filtration (MF) membranes, ultra-filtration (UF) membranes, nano- filtration (NF) membranes, and reverse osmosis (RO) membranes (GUnder, 2001). In membrane filtration systems, the most important concern is the permeate production capacity of the membranes (Le-Clech et al., 2006). Therefore, the specific permeate volumetric flow, also called permeate flux (J in L/m 2•hr), is the most straightforward parameter to measure the hydraulic performance of a membrane system. The calculation of permeate flux is done by dividing the permeate volumetric flow (Q in L/hr) through the membrane by the membrane surface area (A in m 2) (Equation 1.1) (GUnder, 2001). J=Q/A^ (1.1) It is usually assumed that permeate flux is directly proportional to the pressure drop across the membrane (AP in Pa) or the trans-membrane pressure (TMP in Pa) and reciprocally proportional to the absolute viscosity (p. in Pa•s) of the liquid to be filtered and the hydraulic resistance of the filtration system. So the basic assumption is that permeate flux follows Darcy's law (Mallevaille et al., 1996). When filtering water across a membrane, the permeate flux (J) can be expressed as, J=AP/(p,R)^ (1.2) In Equation 1.2, R is the total resistance of the membrane surface with a dimension of reciprocal length and 1..1 is the absolute viscosity of water. 2.3 Type and Mechanism of Membrane Fouling Membrane fouling is a phenomenon that is expressed as the decline of membrane performance, such as a decrease in permeate flux, or an increase in TMP, due to the deposition or adsorption of material on the membrane surface or within the pores of the membranes (Hong et al., 2002). Compounds that foul a membrane are collectively referred as foulants. 6 Membrane fouling is a time-related process that increases with filtration time. Fouling is classified broadly in two categories: reversible and irreversible fouling (Mallevaille et al., 1996). In reversible fouling, foulants are weakly associated with the membrane and thus can be physically removed without much effort. For irreversible fouling, there is a stronger interaction (i.e., chemical bonds) between foulants and the membrane surface or within the membrane structure, such that intensive chemical cleaning is needed to remove the foulant (Geng, 2006). Six different types of fouling mechanisms have been described in MBR applications: scaling, biofouling, organic fouling, pore blocking, cake formation, and feed debris accumulation (Bentem et al., 2001). The formation of scaling on a membrane surface is usually caused by mineral precipitation or deposition. Scaling is not a dominant type of fouling mechanism in MBRs (Jiang, 2007), except perhaps for hard water applications. Biofouling refers to biofilm formation on a membrane surface, which is specifically related to microbial cells, aggregates, and their bio-products, and which results in an unacceptable degree of membrane performance loss (Flemming et al., 1997). Organic fouling is the association of macro-molecules with the membrane surface or deposition in its pores through van der Waals forces, hydrogen bonds, electrostatic interactions, or strong chemical bonds. Organic fouling can be classified as either physical or chemical adsorption (Zeman and Zydney, 1996). Pore blocking refers to the clogging of membrane pores by fine colloids or macro-molecules that are of similar size to that of the membrane pores. Cake formation refers to the development of a layer of colloids or macro-organics on the membrane surface. Many studies have concluded that pore blocking and cake formation are the most common types of fouling for MBR operations (Jiang, 2007). Fouling by feed debris accumulation, e.g. hair, paper, plastic, grease balls, etc., is a matter of concern, especially for MBRs with high SRT and can be partially prevented or alleviated by influent pre-treatment. Normally, several or all of the above mechanisms take part concurrently in the membrane fouling process, with one or two dominating. Due to the simultaneous contribution of these mechanisms in membrane fouling, it is difficult to attribute membrane performance decline exclusively to one mechanism or the other. 7 2.4 Factors Influencing Membrane Fouling Membrane fouling is influenced by all the parameters involved in the design and operation of MBR processes (Le-Clech et al., 2006). The following three categories of factors are defined to determine the nature and extent of membrane fouling in membrane coupled activated sludge processes (Liao et al., 2004). • Physical and chemical parameters of the membrane, • Physico-chemical and biological nature of the feed and mixed liquor, and • Operating conditions. Each of these parameters involves a number of factors influencing the membrane fouling and while these parameters have a direct influence on membrane fouling in MBRs, many others have indirect and complex effects on fouling. The most important factors are discussed below. 2.4.1 Physical and chemical parameters of membrane 2.4.1.1 Membrane material Membrane material plays a very important role in membrane fouling. According to the nature of the membrane material, membranes can be categorized as organic (e.g. polyamide, polysulfone, polypropylene, polyethylene, polytetrafluorethylene, and polyvinyl), inorganic (e.g. ceramic, metallic, porous glass), and modified natural products (e.g. cellulose acetate and cellulose nitrate) (Gander, 2001). Also the types of filtration units available include hollow fiber, tubular, flat sheet, etc. Both inorganic and organic membranes have advantages and disadvantages with respect to fouling. It was reported that the flux of a ceramic micro-filtration membrane was 10-fold higher than the flux in a polymer ultra- filtration membrane when both membranes were producing permeates of similar quality (Ghyoot and Verstraete, 1997). Although ceramic membranes have superior chemical, thermal and hydraulic resistances, ceramic membranes are not the preferred option for MBR applications due to the high cost involved (Judd et al., 2004). For submerged MBR applications, hollow fiber MF and OF membranes made of organic polymers are becoming more and more popular, because of their high packing density and low cost (Jiang, 2007). 8 According to Ghyoot and Verstraete (1997), the cost of an MBR with an inorganic membrane is almost twice that of an MBR with an organic membrane. Also, the organic material used in the membrane can significantly affect the fouling mechanism. A direct comparison between polyethylene (PE) and PVDF membranes clearly indicated that the use of a PVDF membrane leads to a better prevention of irreversible fouling and that PE membranes foul more quickly (Yamato et al., 2006). It was also reported in the literature that the composition of the irreversible fouling observed was dependant on the membrane material, as some fractions of the organic matter present in the mixed liquor have a higher affinity with certain polymeric materials (Yamato et al., 2006). 2.4.1.2 Membrane pore size and distribution The membrane pore size (or molecular weight cut-off) and pore size distribution can affect membrane fouling significantly. The effect of pore size and size distribution on membrane fouling is strongly related to the feed solution characteristics and in particular, to the particle size distribution of mixed liquor (Chang et al., 2002; Le-Clech et al., 2003). Generally, a narrower membrane pore size distribution can reduce the amount of membrane fouling (Fene and Fell, 1987). On the other hand, it was suggested that to limit fouling caused by pore blocking, the pore size distribution of the membrane should have as little overlap as possible with the particle size distribution of the mixed liquor to be filtered. Highly porous membranes with evenly distributed pores provide enhanced filtration efficiency (Mallevaille et al., 1996). 2.4.1.3 Membrane hydrophobicity and charge Membrane hydrophobicity and membrane surface charge have been reported to have important impacts on membrane fouling: (Madaeni et al., 1999; Liao et al, 2004). As hydrophobic interactions occur between solutes, colloids/microbial cells and membrane material, membrane fouling is expected to be more severe with hydrophobic rather than hydrophilic membranes (Chang et al., 1999; Madaeni et al., 1999; Yu et al., 2005). On the other hand, surface charge also plays an important role in biofilm development in the membrane surface. As most bacteria found in activated mixed liquor are negatively charged with a zeta potential ranging from —10 mV to —30 mV, in general, negatively and neutrally 9 charged membranes are not attractive electro-statically to the bacteria in mixed liquor (Kraemer, 2002). Shimizu et al. (1996) observed that negatively charged inorganic membranes fouled less rapidly than neutral or positively charged membranes, as positively charged membranes encourage microbial attachment and thus have greater fouling potential. After an extended filtration period, these surface parameters are expected to play only a minor role in membrane fouling. Once fouled (i.e. conditioned), the membrane's surface characteristics would become secondary to those of the mixed liquor material covering the membrane surface (Le-Clech et al., 2006). 2.4.2 Physico-chemical and biological nature of the feed and mixed liquor In the membrane bioreactor, the feed to the membrane is not wastewater, but activated sludge mixed liquor. Fouling in an MBR is mostly affected by interactions between the membrane and the activated sludge mixed liquor, rather than the wastewater (Choi et al., 2005). Activated sludge mixed liquor is composed of wastewater influent and mixed liquor flocs retained within the system. Therefore, the physico-chemical and biological properties of the mixed liquor are governed by both the nature of the influent wastewater and the characteristics of the mixed liquor flocs. Several physico-chemical and biological properties of mixed liquor, i.e. viscosity, temperature, dissolved oxygen (DO) concentration, floc structure and floc size distribution, hydrophobicity and charge of flocs, EPS contents etc., play significant roles in membrane fouling in MBR processes. 2.4.2.1 Influent characteristics The properties of influent wastewater, including wastewater composition, types and characteristics of contaminants, organic loading, temperature, pH etc. affect the physico- chemical properties of mixed liquor, which in turn affect membrane fouling (Jefferson et al., 2004). An increase in wastewater temperature may alleviate membrane fouling by reducing the viscosity of the mixed liquor, which improves the back-transport of solutes and biosolids from the membrane surface to the bulk fluid (Chiemchaisri and Yamamoto, 1994). When the 10 influent contains non-negligible amounts of inorganic salts, fouling due to mineral precipitation is observed (Tam et al., 2006). In addition to these, it has been shown that soluble chemical oxygen demand (COD) of the influent is responsible for significant portion of membrane fouling (Sato and Ishii, 1991). 2.4.2.2 Mixed liquor parameters Biomass fractionation Based on the size of the mixed liquor particles, mixed liquor can be fractionated into three idealized components, i.e. suspended solids, colloids, and solutes. It has been reported that the main fouling role is played by the soluble and colloidal parts of the mixed liquor (Geng, 2006; Itonaga et al., 2004). Suspended solids in the biomass showed little contribution to the fouling of membranes (Geng, 2006). Although this biomass fractionation is an interesting approach for studying membrane fouling, fractionation experiments neglect any synergistic effects which may occur among the different components of the biomass. The interactions between each biomass fraction and the operating conditions are numerous and hence it is difficult to end up with a definite correlation. MLSS concentration Mixed liquor suspended solids (MLSS) concentration is an important process parameter for operation of an activated sludge system. Although at first sight there appears to be a positive correlation between MLSS concentration and the severity of membrane fouling, MLSS concentration actually demonstrate a complex relationship with MBR fouling, and controversial findings about the effect of this parameter on membrane fouling have been reported. If the other biomass characteristics are not considered, an increase in MLSS concentration primarily has a negative impact (higher TMP or lower flux) on the membrane (Chang and Kim, 2005; Sato and Ishii, 1991). However, some investigators have reported a positive impact (Brookes et al., 2006; Defrance and Jaffrin, 1999a), and some have observed an insignificant impact (Le-Clech et al., 2003; Lesjean et al., 2005). Some other investigators have reported that fouling was independent of MLSS concentration in relatively dilute mixed liquors, until a threshold value was reached, beyond which a sharp negative impact was observed (Le-Clech et al., 2006). Yamamoto et al. (1989) found that the threshold MLSS 11 concentration was about 30 to 40 g/L, and was dependent with the operating conditions. Rosenberger et al. (2006) reported that a rise in MLSS seems to decrease fouling at low MLSS concentration (< 6 g/L), and that more fouling is observed when the MLSS concentration is above 15 g/L. It appears that there is a lack of a clear correlation between MLSS concentration and any other foulant characteristics, which indicates that the MLSS concentration (alone) is a poor indicator of mixed liquor fouling propensity. Some authors have recommended the use of other fundamental operating parameters like hydraulic retention time (HRT) and solids retention time (SRT) for prediction of foulant production (Brookes et al., 2003; Jefferson et al., 2004). Viscosity and temperature In an MBR, as in conventional activated sludge processes, biomass viscosity is considered an important physico-chemical property of the mixed liquor (Itonaga et al., 2004). Viscosity influences membrane filtration performance through an inversely proportional relationship with permeate flux (Equation 1.2). The temperature and the concentration of suspended solids (MLSS) affect the viscosity of a mixed liquor (Gander, 2001). Mallevaille et al (1996) suggested an exponential relationship between MLSS concentration and viscosity of mixed liquor for aerobic mixed liquor. Temperature affects membrane filtration through its influence on the fluid viscosity, such that the viscosity of a fluid increases as temperature decreases. Greater membrane fouling is expected at lower temperatures (Rosenberger et al., 2006). Parameters, such as capillary suction time (CST) and time-to- filter (TTF), which have been widely used for the evaluation of the rate of water release from mixed liquor and the specific resistance to filtration of mixed liquor are also closely related to viscosity (Brookes et al., 2003). Unfortunately, for activated sludge mixed liquor, viscosity is not a constant factor and cannot be used for a complete characterization of the liquid flow properties in membrane filtration (Gander, 2001). Dissolved oxygen concentration The average DO concentration in an MBR is controlled by the aeration rate, which not only provides oxygen to the biomass but also limits fouling formation on the membrane surface by air scouring (Le-Clech et al., 2006). A change in DO may have multiple effects on 12 membrane fouling in an MBR and these effects may include changes in biofilm structure, EPS levels, and floc size distribution (Lee et al., 2003). As a general trend, higher DO tend to be accociated with better filterability of mixed liquor and lower fouling rate (Le-Clech et al., 2006). Floc characteristics For the flocs in activated sludge mixed liquor, surface characteristics such as hydrophobicity and surface charge have been reported to affect the membrane fouling process through hydrophobic and electrostatic interactions between the surfaces of biomass flocs and the membranes (Chang and Lee, 1998; Kraemer, 2002). In addition to these surface characteristics, other physcio-chemical properties of biomass flocs i.e., floc structure, floc size distribution etc., also play significant roles in membrane fouling in MBRs (Wisniewski and Grasmick, 1998). Chang et al. (1999) studied the effects of three different floc structures (normal, pinpoint, and bulking activated sludge mixed liquor) on membrane fouling behaviour. The study indicated that bulking sludge had the highest fouling propensity, followed by pinpoint sludge and then normal sludge. It is reported in the literature that higher hydraulic resistance was, to some extent, associated with a smaller floc size distribution of activated sludge mixed liquor, which is induced by the intensive recirculation in a recirculated MBR process (Jang et al., 2005; Wisniewski and Grasmick, 1998). Extracellular polymeric substances (EPS) The term EPS refers to extracellular polymeric substances, which are biosynthesized, secreted, and released by microbial cells due to cell metabolism, shedding of cell surface material or cell lysis (Frolund et al., 1996; Mallevaille et al., 1996). Chemically, EPS is a pool of complex organic matter that typically consists of carbohydrates (polysaccharides), proteins (including enzymes), humic-like substances, DNA, lipids, nucleic acids and uronic acids (Dignac et al., 2000; Spaeth and Wuertz, 2000). In general, EPS is classified according to the phase with which it is associated in mixed liquor. For example, bound EPS is associated with biomass floc, and soluble EPS is present in the soluble and/or colloidal part of mixed liquor. The soluble EPS is often referred to as soluble microbial products (SMP) (Laspidou and Rittmann, 2002). It is important to recognize that the exact definitions of 13 bound EPS and soluble EPS are directly dependant on the methods used to obtain and chemically characterize these solutions (Le-Clech et al., 2006). Since bound EPS are adhesive and viscous they can act as the construction materials for microbial aggregates such as biofilms and flocs. The EPS matrix plays multiple functions in an MBR process, including aggregation of bacterial cells in flocs and biofilms, formation of a protective barrier around the bacterial floc, and retention of water and adhesion to surfaces (Laspidou and Rittmann, 2002). In addition to these, bound EPS can be responsible for the creation of a significant barrier to permeate flow in membrane processes. EPS can form a highly hydrated gel matrix in which microbial cells remain embedded, and bioflocs attached to the membrane can serve as a major source of nutrients during biofilm formation on the membrane surface (Flemming et al., 1997; Wingender et al., 1999). High contents of bound EPS have been measured in MBR processes and their effects on MBR filtration have been reported for more than a decade (Nagaoka et al., 1996; Kraemer, 2002; Ng and Hermanowicz, 2005). A considerable number of publications in recent years indicates that the bound EPS can be considered one of the most significant factors affecting membrane fouling in MBRs (Chang et al., 2002; Cho and Fane, 2002; Liu and Fang, 2003; Nagaoka et al., 1996 and 1998; Rosenberger and Kraume, 2002). On the other hand, some researchers reported that there was no clear relation found between membrane fouling and bound EPS contents of activated mixed liquor in MBRs (Geng, 2006; Pattanayak, 2007). Among the components of bound EPS, carbohydrate and protein have received the most attention. However, the measurement of humic-like substances has revealed their significant occurrence in activated mixed liquors, and these may require more consideration in future research on MBR fouling (Le-Clech et al, 2006; Liu and Fang, 2003). Many parameters, including cross flow velocity, aeration, substrate composition, and loading rate, affect bound EPS characteristics in MBR reactors, but it appears SRT has the most significant effect (Le-Clech et al., 2006; Ng and Hermanowicz, 2005; Rojas et al., 2005). A reduction of bound EPS levels was observed at an extended SRT, but this reduction of bound EPS level became negligible when the increased SRT value reached 30 days or 14 more (Brookes et al., 2003). However, contradictory trends have also been reported in the literature. Lee et al., (2003) observed that protein concentration increased (along with stable carbohydrate levels) when SRT was increased. Since the bound EPS matrix plays a major role in the floc formation, it was proposed and proven that a decrease in bound EPS levels may cause floc weakening and breakup (Brookes et al., 2003; Jang et al., 2005). Hence, the consequences of low EPS levels may include detrimental effects on MBR performance. This indicates that there should be an optimum bound EPS level for which floc structure is maintained without featuring high fouling propensity. Like bound EPS, soluble EPS can also be characterized through its relative amounts of protein, carbohydrate and humic-like substances (Geng, 2006). During filtration, soluble EPS may block membrane pores, adsorb on the membrane surface and/or form a gel structure on the membrane surface, where they provide a possible nutrient source for biofilm formation, which in turn, imposes added hydraulic resistance to permeate flow (Rosenberger et al., 2005). Although the influence of dissolved matter on membrane fouling in MBRs has been studied for a decade, the concept of soluble EPS fouling is relatively new (Chang et al., 2002). Within a short time, several publications have indicated that soluble EPS, and particularly the carbohydrate fraction, is one of the main parameters affecting MBR fouling (Cabassud et al., 2004; Evenblij et al., 2005; Grelier et al., 2005; Le-Clech et al., 2005; Lesjean et al., 2005; Rosenberger et al., 2005). However, more detailed characterization of the soluble fraction of activated sludge mixed liquor and the fouling layer reveals that a significant role is played by the protein as well as the humic-like substances (Drews et al., 2005; Evenblij and Graff, 2004; Geng, 2006). As for bound EPS, many operating parameters, including cross flow velocity, substrate composition, and loading rate also affect soluble EPS levels in MBRs (Brookes et al., 2003; Grelier et al., 2005). Rosenberger et al., (2006) identified temperature and stress to the micro-organisms, resulting from variable operating conditions (and to a lesser degree, 15 SRT) to be the main parameters affecting soluble EPS concentration and composition in MBR processes. Generally, various physico-chemical properties of activated mixed liquor have been investigated separately with regard to their effects on mixed liquor fouling potential, but these parameters are essentially interrelated and integrated as a whole when biomass flocs interact with the membrane during filtration. Due to this, it is hard to assess the effect of one parameter conclusively. So far, the correlations between these physico-chemical properties and their combined impact on membrane fouling in MBRs have not been extensively studied. 2.4.3 Operating conditions 2.4.3.1 Permeate flux and trans-membrane pressure The two most important operating parameters of a membrane filtration process are permeate flux and trans-membrane pressure. The economic viability of the MBR depends on the optimized permeate flux, mainly controlled by effective fouling control with modest energy input (Le-Clech et al., 2006). To control and minimize fouling, the filtration system should be operated within a proper operation window in which both flux and TMP cannot be set too high. Constant flux operation is currently the mode of choice in many MBR applications, because the use of constant flux and the monitoring of resultant TMP rise have proved to be easy to monitor and control the fouling of membrane in activated mixed liquor (Le-Clech et al., 2006). Field et al. (1995) first introduced the concept of critical flux for micro-filtration fouling, hypothesizing that a critical flux exists, below which a decline of permeability with time does not occur, and above which fouling with time is observed. The value of critical flux depends on the back-transport provided by the cross-flow or turbulence generated by the imposed liquid flow and/or bubbling as well as the specific solute—membrane interactions, and probably other variables (Madaeni et al., 1999). Defrance and Jaffrin (1999b) investigated the reversibility of membrane fouling in an MBR process, and found that when the permeate flux was set below the critical flux, the TMP remained stable and the fouling 16 was reversible. On the other hand, when the filtration was done with a flux that was greater than the critical flux, the TMP increased and did not stabilize. The fouling was found to be partly irreversible when the flux was lowered. Selecting an appropriate permeate flux was concluded to be of crucial importance to obtain the best compromise between flux and TMP to operate an MBR process economically. 2.4.3.2 Aeration and cross flow velocity For a submerged MBR, bubbling has been defined as the strategy of choice to induce flow circulation and shear stress on the membrane surface to ensure sufficient turbulence to prevent adhesion and deposition of floc particles on the membrane surface (mitigating fouling) (Le-Clech et al., 2006). Beyond this scouring of the membrane surface, the aeration used in MBR systems also provides oxygen to the biomass and maintains the activated mixed liquor in suspension (Dufresne et al., 1997). In submerged MBR processes, the rate of permeate flux decline is usually reduced with an increase of aeration intensity. Bouhabila et al. (2001) reported that, by increasing the air flow rate from 1.2 to 3.6 m 3/m2•hr., it was possible to decrease the total hydraulic resistance and thus increase the permeate flux by a ratio of 3. Like flux and TMP, there also existed an optimum aeration rate, beyond which a further increase had no significant effect on flux enhancement (Hong et al., 2002; Liu et al., 2003; Ueda et al., 1997). As intense aeration could result in an over-supply of dissolved oxygen that could hinder the denitrification process in a BNR system, a suitable aeration intensity should be determined to meet the requirements for both fouling control and nitrogen removal. Intense aeration may also break up bacterial flocs, and release EPS in the bioreactor (Ji and Zhou, 2006). 2.4.3.3 Solids retention time SRT (and consequently the F/M ratio), has long been a major concern with regard to its influences on both the biological conversion process and the membrane fouling. Trussell et al., (2006) monitored membrane fouling at SRTs of 2 days and 10 days, and found that 17 fouling rate increased nearly 10-fold when SRT was lowered from 10 days to 2 days. A similar negative effect of lower SRT on membrane fouling was reported by other researchers (Chang and Lee, 1998; Fan et al., 2000). Accordingly, it can be concluded that the fouling propensity of activated mixed liquor decreases as SRT increases. At the other end of the spectrum, the increase in MLSS concentration related to high SRT could also result in a higher fouling propensity. In one study, it was found that when the SRT was increased from 30 to 100 days, fouling was nearly twice as great for the longer SRT conditions even with the aeration raised significantly (Han et al., 2005). Similar results were reported by van Houten et al. (2001) who observed that at a long SRT, micro-organisms in activated mixed liquor tended to disintegrate and excreted soluble EPS, leading to high mixed liquor viscosity and a high fouling propensity. Considering the close relationship of SRT to MLSS concentration and the diverse research results on the effect of MLSS concentration on membrane fouling, it is likely that an optimal value may also exist for SRT between the high fouling potential of mixed liquor of very low SRT operation and the high viscosity suspension prevalent for very long SRT (Le- Clech et al., 2006). The discrepancy in the literature regarding the effect of MLSS concentration on membrane fouling in MBR systems is likely due to the effect of SRT on membrane fouling. 2.4.3.4 Transient operating conditions Transient or dynamic operating conditions (such as variations in flow input/HRT and organic load/SRT and shifts in oxygen supply/DO concentration) have also been defined as additional factors leading to changes in MBR fouling propensity (Le-Clech et al., 2006). In real-world applications, such dynamic operating conditions could occur regularly. There is a diurnal wastewater flow variation observed at municipal wastewater treatment plants. Normally, there are two peak flows and two minimum flows in the diurnal flow variation pattern. The variation between the high and low flows mainly depends on the community size served by a treatment plant (Tchobanoglous, 2003). 18 Drews et al. (2005) carried out an experiment at a small pilot-scale MBR (120 L), in which the effects of unstable flow input and unintentional mixed liquor wastage were assessed. It was reported that the concentration of polysaccharides (a component of EPS) increased before and after each mixed liquor withdrawal. The increase before mixed liquor withdrawal was explained by the increasingly high MLSS concentration and the resulting low DO level in the bioreactor, and the increase after wastage was due to the sudden stress experienced by cells. It was concluded that transient operation could accelerate membrane fouling. Evenblij et al. (2005) reported that for a short-term batch test, other transients in operation, such as a dynamic influent pattern and a spike of acetate in the feed water also significantly decreased the filterability of the biomass in an MBR; this was due to a rise in EPS levels. Further research work is required to understand the exact impact of dynamic operation on MBR fouling to implement more sustainable MBR operation. 2.5 MBR Fouling Control Membrane fouling control is the most important aspect and most challenging task in MBR design and operation. Fouling prevention and control strategies could be implemented in an integrated way, as almost every wastewater treatment step has an effect on membrane fouling. The major membrane fouling control aspects are listed below. 2.5.1 Removal of fouling Membrane cleaning, the most straightforward means of fouling control, is usually classified as physical cleaning or chemical cleaning. Physical cleaning, otherwise refered to as maintenance cleaning, mainly involves mechanical methods such as relaxation, permeate/air backpulsing and backflushing. Chemical cleaning is mainly recovery cleaning that usually involves a cleaning step using chemical oxidants like Na0C1, NaOH, H202, C12, etc. (Geng, 2006) 19 2.5.2 Limitation of fouling Optimization of membrane characteristics helps to limit fouling. This can be done by careful selection of the membrane by considering the pore size and distribution, surface charge, hydrophobisity, chemical stability, mechanical strength, module packing density and, eventually, cost (Jiang, 2007). Influent pre-treatment is the first step to prevent some potential foulants from entering the filtration system. It involves most of the common preliminary and primary treatment procedures that remove or reduce influent debris and colloidal particles that are detrimental to a filtration membrane. In addition, influent pH adjustment is also important for mitigation of membrane fouling due to mineral precipitation. Hydrodynamic control of filtration system for limitation of fouling includes sub- critical flux operation, non-continuous filtration operation, constant-flux operation mode, and turbulent aeration/ recirculation (Hong et al., 2002). Addition of adsorbents such as powdered activated carbon (PAC) or coagulants such as alum and zeolite has been proven to be effective in alleviation of membrane fouling in wastewater treatment MBRs (Holbrook et al., 2004; Seo et al., 2005). Proper design and operation of MBR process to produce activated sludge mixed liquor with high filterability is a very promising way to limit membrane fouling. It has been demonstrated that through optimization of the biological system in an MBR process, EPS concentration could be minimized or produced in a form that did not reduce the dewaterability or filterability of the activated mixed liquor (Lawrence et al., 2001). 2.6 Research Scope and Objectives From the literature review presented, it appears that, although intensive research has been done on membrane fouling in the MBRs for more than a decade, a consensus of exact 20 fouling phenomena has not been reached yet. This is due to the fact that membrane fouling in an MBRs is a very complex phenomenon that depends on various interrelated physio- chemical, biological and operational parameters of the MBR process. Therefore, a more comprehensive and thorough study is needed to better understand membrane fouling in MBR processes. The scope of this present research study was defined to focus on the correlation of the dynamic operational conditions of activated sludge process to the membrane fouling in a MBR process. The overall objective was, to better understand membrane fouling phenomena under different operating conditions and thereby, optimize MBR process to reduce membrane fouling and achieve long-term stable membrane filtration performance, without compromising the biological treatment performance. The specific research objectives are to find the answers of the following questions. 1. Is there any impact of transient (dynamic) operation on the performance of an MBR process, as well as on membrane fouling? 2. What is the correlation between membrane fouling and physico-chemical and biological properties of activated sludge mixed liquor, and what are the key mixed liquor properties that significantly influence the fouling propensity of mixed liquor? 3. Is there any correlation between the solids retention time (SRT) and membrane fouling in an MBR that is subjected to dynamic operating conditions? 21 CHAPTER THREE MATERIALS AND METHODS The present MEBPR research study was conducted at the University of British Columbia (UBC) wastewater treatment pilot plant between October 2006 and June 2007. The study was designed to investigate membrane fouling under different operating conditions. 3.1 The UBC Wastewater Treatment Pilot Plant For comparison purposes, the UBC pilot plant facility provided two parallel activated sludge systems that could be operated with different experimental treatments or process designs. The two parallel trains shared the same raw sewage influent and both operated under comparable process design and operating conditions. Wastewater was pumped from a nearby sump pump connected to a trunk sewer, into two large storage tanks at 3:00 am, 9:00 am, 3:00 pm and 9:00 pm, daily, before it entered the treatment systems. Approximately 1.5 kg of sodium bicarbonate was added to each storage tank daily, as the alkalinity of the influent wastewater was low (Monti, 2006). There was a common primary clarifier serving both systems. Both trains utilized an anaerobic zone, an anoxic zone and an aerobic zone. The liquid volumes of the anaerobic (A), anoxic (B), and aerobic (C) zones of the two trains were 0.23, 0.59, and 1.32 m3 , respectively. The anoxic recycle ratio and aerobic recycle ratio of mixed liquor were 1:1, relative to the influent flow rate. Membrane modules were used for solids-liquid separation. The facility integrated membrane technology with the University of Cape Town (UCT)-type biological phosphorus removal process. For the present research study, one train was operated with constant inflow (side-C) and the other train with a variable inflow (side-V). In the side-C train, influent flowed at the rate of 3.7 L/min. In the side-V train, the flow rate of influent fluctuated to vary both the hydraulic and organic loading rates. The influent flow rate fluctuated as follows: @ 1.4 L/min from 1:00 am to 7:00 am, @ 6.0 L/min from 7:00 am to 1:00 pm and @ 3.7 L/min 22 from 1:00 pm to 1:00 am. This gave an average rate of 5330 L/day, which was equivalent to the total daily inflow of side-C. The two trains were investigated at SRTs of 20 days and 10 days, while keeping the HRT at 10 hours. A schematic of the UBC wastewater treatment pilot plant is shown in Figure 3.1. 3.1.1 The filtration membrane module It was necessary to use two different types of membrane modules in the present study, including operational membrane (OM) modules and test membrane (TM) modules. The OM modules were a functional part of the MEBPR processes, as they provided the required solids-liquid separation capacity. These operational modules were big and heavy to maneuver. So when the membrane modules were fouled, a substantial amount of work was needed to do the membrane cleaning procedure for these OM modules. Also, during the cleaning procedure for these OM modules, the MEBPR process flows needed to be disrupted for several hours. Since one of the main objectives of the present study was to investigate membrane fouling under different operating conditions, the membrane modules under investigation needed to foul several times. A small and robust membrane module, which was easy to handle, was used to do the present fouling research study. Bench scale membrane modules (ZW-10, GE Water & Process Technologies, ZENON Membrane Solutions, Oakville, Canada) were selected as the test membrane modules for the online filtration study, as they were robust in design with a reasonably small size. These modules were easy to remove and clean, without disruption of the process flow. Two custom-built pilot scale membrane modules (ZW-500, GE Water & Process Technologies, ZENON Membrane Solutions, Oakville, Canada) were used in the aerobic zones of each process train as the OM bundle. The module specifications and operating limits are listed in Table 3.1. 23 Holding Tank• Influent PO Side C: Constant inflow Mixer P13 Perrieate C--)^-tank P11^i v Permeation Air sparging (A4^(A3) (A2)^(A1) OMAnoxic 12 Sewer V P8 Flow 1.4 L/min (from 1:00 AM to 7:00 AM) 6.0 L/min (from 7:00 AM to 1:00 PM) 3.7 L/min (from 1:00 PM to 1:00 AM) Mixer Anaerobic I ) P9 © P1 P12 P2 Flow 3.7 L/min Primary Clarifier P4P3 P6 Sewer ) o^OM r ^Mixer^Mixer^(A4 ^ I I I I Anaerobic'^Anoxic ^0 I )^I I I  Aerobic P5 Permeation Air sparging (A3) (A2>^CAD P7 Perrieate „tank P10 Sewer 1Side V: Variable inflowl Figure 3.1. Schematic of the UBC wastewater treatment pilot plant. Al, A3 and A4: Air sparging system of operational membrane (OM) and test membrane (TM) modules, respectively. A2: Fine bubble air sparging system to maintain DO concentration. PO to P13: Pumps in the pilot plant system. When in service, the modules were submerged in the aerobic zones of the trains and operated in a cyclic mode, that is, under vacuum for 9 minutes and 30 seconds and then back- flushed with permeate for 30 seconds. Each filtration cycle lasted 10 minutes, as no relaxation was applied. Aeration was supplied around the membrane in a cyclic mode of 10 second ON and 10 second OFF, with an airflow rate of 0.28 to 0.34 m3/min (10 to 12 scfm) in order to minimize fouling and maintain a target dissolved oxygen (DO) level of 2.5 mg/L. Constant-flux operation was used in the OM modules. In order to reduce the cleaning frequency of these modules, the fluxes were maintained as low as possible, with just enough flux to maintain a 10 hour hydraulic retention time (HRT). The trans-membrane pressure (TMP) of the OM modules was monitored to track the extent of fouling and to decide whether a chemical cleaning was required. When the TMP reached the maximum operating limit of 69 kPa (10 psi), the modules were removed from the aerobic compartment and subjected to a recovery chemical cleaning. Table 3.1. Specifications and operating limits of the operational membrane module Model Custom-built ZW-500, submersible Configuration Outside/In hollow fiber Membrane material Polyvinylidene fluoride (PVDF) Nominal Membrane Surface Area 11.9 m2 Nominal Membrane Pore Size 0.04 [un Membrane Surface Chemistry Neutral and hydrophilic Dimension (approximately) 100 cm x 100 cm x 15 cm Maximum Trans-membrane Pressure 69 kPa (10 psi) Maximum Operating Temperature 40°C Operating pH range 5 — 9 Source: Geng (2006) 25 Parallel to the OM modules, two bench scale TM modules were installed in each MEBPR train. The ZW-10 module specifications and operating limits are listed in Table 3.2. The TM modules were operated with a relatively constant flux of 30 L/m 2 •hr. Like the OM modules, these TM modules were also submerged in the aerobic zones of the trains and operated in a cyclic form. In this case, vacuum for 9 minutes and 30 seconds and relaxation for 30 seconds were applied. Each filtration cycle lasted 10 minutes. For the TM modules, aeration was supplied at a constant airflow rate of 0.28 m 3/min (1 scfm). Recovery chemical cleaning was undertaken after each filtration experiment. Table 3.2. Specifications and operating limits of the test membrane module Model ZW -10, submersible Configuration Outside/In hollow fiber Nominal Membrane Surface Area 0.93 m2 Nominal Membrane Pore Size 0.04 iim Membrane Surface Chemistry Neutral and hydrophilic Dimension (approximately) 100 cm x 100 cm X 15 cm Maximum Trans-membrane Pressure 62 kPa (9 psi) Maximum TMP Back Wash Pressure 55 kPa (8 psi) Maximum Operating Temperature 40°C Operating pH range 5 — 9 Source: Rabie et al., (2005) 3.2 Modification of UBC Pilot Plant Before the start of the present study, the pilot plant had been operating with two parallel wastewater treatment systems in two different configurations for more than three years. One side was running as a membrane enhanced biological phosphorus removal process (MEBPR) and the other one was running as a conventional enhanced biological phosphorus 26 removal process. For more details on the design and operation of the UBC Wastewater Treatment Pilot Plant at that time, please refer to Monti (2006). For the purposes of the present study, the conventional side was converted to an MEBPR configuration on the 31 st October 2006 (considered as the first day of operation). Before starting the variable loading in side-V, the mixed liquor in both trains was mixed completely by the exchange of aerobic recycle. 3.3 Experimental Program The MEBPR trains were operated at a 20 day SRT from day 1 to day 184 (Run SRT20) of the program and at a 10 day SRT from day 185 to day 219 (Run SRT10). Mixed liquor from both trains was completely mixed when switching to a 10 day SRT. Three different filtration experiments were completed with the TM modules installed in the aerobic zones. The first two filtration experiments (FE SRT20a and FE SRT20b) were performed at a 20 day SRT, to characterize and compare the membrane fouling in both parallel processes. The third filtration experiment (FE SRT10a) was performed at a 10 day SRT (One filtration experiment was done at 10 day SRT because it was not possible to do another filtration experiment within the allocated time for the present project). TM modules were installed in the aerobic zones from day 129 to day 147, day 154 to day 171, and day 206 to day 210 of the operation, for experiment FE SRT20a, FE SRT20b and FE SRT10a respectively. 3.4 Routine Membrane Maintenance 3.4.1 Membrane integrity testing Before starting each filtration experiment, the integrity of the TM modules was verified using a bubble test performed at a pressure of 41 kPa (6 psi). The bubble test was performed by following the procedure stated by Lei (2005). During the test, if any bubbles were observed in the system, it was concluded that the integrity of the membrane was compromised. If that was the case, then the integrity problem 27 was eliminated by cutting the membrane fiber and sealing the open edge with 5 minute epoxy glue. 3.4.2 Membrane cleaning 3.4.2.1 Operational membrane module When the TMP of the OM modules reached the maximum operating limit of 69 kPa (10 psi), the modules were chemically cleaned to recover the permeability of the membranes. The cleaning procedure used during the present study was as follows. I. After removal from the aerobic zone, the membrane modules were rinsed with tap water to remove scum and grit. II. The membranes were then soaked in a 2000 mg/L bleach (sodium hypochlorite) solution for about 24 hours. III. The membrane modules were rinsed and soaked in tap water for 30 minutes. IV. The membrane modules were soaked in a 2000 mg/L citric acid solution at approximately pH = 2 for about 24 hours. V. The membrane modules were rinsed with tap water and soaked into a 2000 mg/L bleach (sodium hypochlorite) solution for future use. VI. Finally, before the cleaned membrane modules were used for filtration, the modules were rinsed again with tap water. 3.4.2.2 Test membrane module The TM modules were chemically cleaned after each filtration experiment run to recover the permeability of the membranes. The cleaning procedure used during the present study was as follows. I. After removal from the aerobic zone, the membrane modules were rinsed with tap water to remove scum and grit. II. The membranes were then soaked into a 2000 mg/L bleach solution for about 24 hours. During the soaking period, the bleach (sodium hypochlorite) solution was filtered through the membrane modules at a flux of 10 to 15 L/m 2 •hr for about 12 hours; 28 Membrane fibers Permeate line Top header Pressure gauge line III. After bleach soaking the membrane modules were rinsed and then soaked in tap water for 10 minutes and then operated in filtration mode with tap water for approximately 5 minutes. IV. After rinsing with tap water, the modules were soaked in a 2000 mg/L citric acid solution at approximately pH = 2 for 16 to 24 hours. During that time, membrane modules were permeated with citric acid solution for about 6 to 8 hours with a flux of 10 to15 L/m 2 -hr. V. Before the cleaned membrane modules were used for filtration testing, the membrane modules were rinsed again with tap water. Subsequently, tap water was filtered through the membrane modules for a period of 10 to 15 minutes. 3.5 Effective Surface Area of Test Membrane Module For the present study, ZW-10 modules were selected as test membrane (TM) modules (Figure 3.2), as these modules could be easily installed and operated (Section 3.1.1). The module specifications and operating limits are listed in Table 3.1. Figure 3.2. ZW-10 test membrane module. All the TM modules had two holes on the top header, one for permeation and one for pressure measurement. The permeation could be done only from the top header. Each module 29 #1 Module #2 Module had approximately 300 membrane fibers, which in total, provided a surface area of approximately 0.93 m2 . A membrane fiber must have an opening in to the top header to allow filtration through that fiber. If, the openings of one or more fibers are blocked in the top header, there will be no permeation through those membrane fibers. As a result, the overall effective filtration surface area of the module will be less than the specified value (0.93 m 2). From a visual inspection through the holes of the top header, it was found that some of the fibers were sealed in two of the TM modules (#1 and #3) used in the present study (Figure 3.3). Figure 3.3. Condition of the membrane opening inside the header of #1, #2 and #3 test membrane modules. As a result, these membrane modules had an effective surface area that was lower than that specified by the manufacturer. The effective surface area of a membrane module is an important parameter to calculate flux through the membrane. Therefore, the effective surface areas of these membrane modules were estimated with respect to one of the TM module (#2 Module in Figure 3.3) which did not appear to have any sealed fibers, and so, was assumed have an effective specified design surface area of 0.93 m 2 . Estimation of the effective surface area for each TM module was done after chemical cleaning of the membrane module. To calculate the effective surface area, each membrane module underwent a clean water flux test. Clean water was permeated through the membrane at several flow rates and the corresponding TMP values were recorded. From these data a TMP 30 0 100 200 300 400 500 600 25 Reference membrane module with assumed surface area of 0.93 s.. m vs. flow graph for each module was constructed, which was a straight line as shown in Figure 3.4. From the graph, the flow for each membrane module could be estimated for an arbitrary TMP. i.e. 10 kPa (1.5 psi). The effective surface area of the each membrane module was then calculated by using the following equation. Aeffective Areference X FlOW/FlOWreference ^ (3.1) Flow (mUmin) Figure 3.4. TMP vs. flow graph to calculate effective surface area of ZW-10 membrane modules. In Equation 3.1, Aeffective is the estimated effective surface area of a membrane module and Areference is the surface area of the reference TM module as provided by the membrane manufacturer (0.93 m 2). The flow in Equation 3.1 corresponds to that for the TM module being considered, obtained from the graph for an arbitrary TMP. Flowreference represents the flow for the reference TM module, obtained from the graph for that arbitrary TMP. An effective surface area calculation of the test membrane modules was done before 31 every experimental run. Table 3.3 shows the effective surface areas of the TM modules after each chemical cleaning during the course of the present study. Table 3.3. Calculated effective surface area of the test membrane modules Test membrane module Effective surface area in m2 , at operating day (Date) 128 (7-Mar-07) 152 (31-Mar-07) 183 (1-May-07) 205 (23-May-07 159 (3-June-07) #1 0.52 0.51 0.63 0.62 0.67 #2 Areference — 0.93 #3 0.73 0.82 0.87 0.90 0.89 From Table 3.3 it can be seen that effective surface area of the #1 and #3 TM modules were increased with the use of the membrane modules. This may have happened due to progressive opening of some of the sealed membrane fibers during membrane use. After finishing all the experimental runs, the three TM modules (#1, #2 and #3) were investigated thoroughly by removing the top covers of the top headers (Figure 3.5).  #3 Module#1 Module #2 Module Figure 3.5. Condition inside the header of #1, #2 and #3 TM modules after all experimental test runs. 32 It was found that #2 TM module (previously considered a reference membrane module) did not have any sealed fibers. On the other hand, sealed fiber were observed the #1 and #3 TM modules. The number of open membrane fibers was determined for every TM module, and the effective surface area of filtration was estimated based on the number of open fibers (Table 3.4). Table 3.4. Number of effective membrane strands and calculated effective surface area of the test membrane modules and their ratio. Test membrane module Estimated effective surface area in m2, at operating day 159 Number of open membrane strands at operating day 225 (after finishing all experimental runs) Ratio with respect to reference membrane module (#2 module) Effective surface area Number of open strands #1 0.67 205 0.72 0.707 #2 0.93 290 1 1 #3 0.89 275 0.957 0.948 From Table 3.4, it can be seen that the ratios of the estimated effective surface area and the ratios of the number of open membrane strands were close. This indicates that the method used to estimate effective surface area in the present study was reasonably accurate. 3.6 VFA Supplementation From previous study at the UBC wastewater treatment pilot plant it was found that the VFA to total phosphorus ratio of the influent wastewater was too low to remove phosphorus satisfactorily in the process (Monti et al., 2007). Sodium acetate (7000 mg/L) was added at a rate of 22 mL/min to the anaerobic zones as a supplemental carbon source (VFA), to maximize the phosphorus release. A total of 140 liters solution was prepared in a batch, once every two days. 33 3.7 Maintaining Dissolved Oxygen Level In addition to the membrane air sparging systems, a fine bubble aeration system was also installed in the aerobic zones of the MEBPR systems to maintain the DO concentration at approximately 2.5 mg/L. The zone was equipped with a DO controller (model 1972-00, Cole-Parmer Canada, Inc., Montreal, Canada) and DO probe (model C-05726-00, Cole- Parmer Canada, Inc., Montreal, Canada) to control the DO concentration. When DO in the zone fell below 2.5 mg/L, the DO controller automatically turned on the fine bubble air sparger to supply additional air to increase the DO concentration. When the DO reached the target 2.5 mg/L, the controller stopped the fine bubble air sparger. 3.8 Maintaining Solids Retention Time (SRT) The SRT was maintained by wasting mixed liquor from the aerobic zones of each train. Wasting was done once per day based on total suspended solids (TSS) measurement. The following equation was used to calculate wasting volume from the aerobic zone. Xanaerobic • Vanaerobic + Xanoxic • Vanoxic + Xaerobic • Vaerobic Wasting volume (L/day) = ^ (3.2) Xaerobic • SRT Where, Xanaerobic Xanoxic Xaerobic Vanaerobic Vanoxic Vaerobic = TSS of anaerobic zone = TSS of anoxic zone = TSS of aerobic zone = Volume of anaerobic zone = Volume of anoxic zone = Volume of aerobic zone 34 3.9 Monitoring 3.9.1 Monitoring of reactor performance A systematic sampling and analysis schedule was developed to monitor the performance of both trains. Table 3.5 summarizes the sampling frequency for the parameters that were monitored. The influent samples were taken from the holding tank and the effluent samples were taken from the permeate tanks. Mixed liquor samples were collected from each zones of both trains. In every case, the contents of the zones were well mixed before sampling. The temperature, pH, dissolved oxygen concentration were usually taken once per day. Temperature and DO were measured using portable meter (VWR sympHony probe, VWR International, Inc., West Chester, USA) and pH was measured using another portable meter (OAKTON Wd-35801-00 probe, Fisher Scientific Company, Ottawa, Canada). The instruments used for measuring pH, temperature and DO were usually calibrated at least two times per week. 3.9.2 Monitoring of fouling parameters In addition to routine monitoring of the reactor performance, additional membrane fouling parameters were also monitored during the TM filtration experiments. Mixed liquor samples were collected two times per week from the aerobic zones to monitor gross filterability properties of the mixed liquor based on capillary suction time (CST) and time to filter (TTF). Critical flux, which is another parameter that reflects the fouling propensity of the mixed liquor, was determined twice during the whole study period. The first critical flux test was conducted during Run SRT20 and a second during Run SRT10. Trans-membrane pressure, which reflects the rate and extent of membrane fouling, was monitored continuously (PX240A, Omega Engineering, Inc., Laval, Canada) for the TM modules and recorded at least once per minute (HOBO U12 outdoor/industrial 4 ext Channels data logger, onset Computer Corporation, Bourne, MA, USA) 35 For the OM modules, TMP data were collected once per day by using a pressure gauge (C-689500-00, Cole-Parmer Canada, Inc., Montreal, Canada). Mixed liquor samples were also collected once per week from the aerobic zones to analyze biochemical properties of mixed liquor, including soluble and bound EPS. Table 3.5. Sampling frequency for different analytical parameters Parameter Sampling Location Influent Effluent Anaerobic Anoxic Aerobic Temperature a a a pH a Dissolved Oxygen a COD (total) a COD (soluble) a a NH4-N a a b b b VFA a b PO4-P a a b b b NOR-N a a b b b TSS b b b TKN b TP b a = daily; b = two days per week 3.10 Sample Handling and Preservation The mixed liquor samples collected from the aerobic zones were preserved in accordance with the prescribed methods in Standard Methods (Clesceri et al., 1998). Samples for soluble COD, VFAs, ammonium-nitrogen, ortho-phosphate, nitrite plus nitrate nitrogen were filtered with glass fiber filter papers (G6, Fisher Scientific Company, Ottawa, Canada). After preservation, the samples were kept in a refrigerator at 4°C in the pilot plant. 36 TSS, CST and TTF analyses were completed at the pilot plant, immediately after the sampling. The preserved samples were taken to the Civil Engineering Department (UBC) Environmental Laboratory for analysis. 3.11 Analytical Methods The analytical methods used in the analyses are presented below. However, complete details can be found in Standard Methods (Clesceri et al., 1998). 3.11.1 Permeate flux measurement In the present study, the permeate flux was defined as the volumetric rate of liquid flow through a unit area of membrane surface. The units used for expressing flux were L/m2 -hr. Permeate from a membrane module was collected in a container for a known time period (4 to 30 minutes) and the volume was measured with a graduated cylinder. To calculate the flux through the membrane module, the following equation was used: Flux = (Volume filtered / time) / effective surface area of the module^(3.3) 3.11.2 Total and soluble COD The COD samples were prepared and analyzed by the closed reflux, colorimetric method as described in Standard Method 5220 D (Clesceri et al., 1998). Influent and effluent soluble samples were collected by filtering the samples with glass fiber filter papers (G6, Fisher Scientific Company, Ottawa, Canada). For COD analysis, a 2 mL sample was collected in a previously prepared test-tube filled with 4 mL standard reagent. Standard reagent was prepared in accordance with Standard Method 5220 D by mixing 1.2 mL digestion solution with 2.8 mL of sulfuric acid reagent (Clesceri et al., 1998). High range reagent was used to analyze the influent (total and soluble) samples. Low range reagent was used to analyze the effluent soluble COD samples. The samples were analyzed in HACH DR2800 Direct Reading Spectrophotometer (Anachemia Science, Vancouver, Canada). 37 3.11.3 Volatile fatty acids The gas chromatograph (GC) method was used for analysis of VFA in the samples. The influent VFA samples were filtered through glass fiber filter papers (G6, Fisher Scientific Company, Ottawa, Canada) and stored in 2 mL glass vials. One drop of 2% phosphoric acid solution (H3PO4) was added to each vial to preserve the sample. Filtered samples were analyzed in a HP 5890 Series II gas chromatograph with Flame Ionization Detector (FID) (Agilent Technologies, Richmond, Canada). The specifications of the GC used for the analysis was as described in Table 3.6. Table 3.6. Specifications of the gas chromatograph Column HPFFAP 25 m x 0.32 mm x 0.25 1,tm film Detector Helium (He) Carrier, 7 psi (48 kPa) Head Pressure Injection Temperature 175° C Detector Temperature 250° C Oven Initial Temperature 130° C Oven Final Temperature 150° C 3.11.4 Ammonium-nitrogen The automated phenate method (Standard Method 4500-NH 3 H) was used for ammonium-nitrogen analysis (Clesceri et al., 1998). Filtered samples for ammonium- nitrogen were preserved using 5% v/v sulphuric acid (H 2 SO4) to approximately pH 2. For measurement, a Lachat Quik-Chem 8000 flow injection analyzer (ATS Scientific Inc., Burlington, Canada) was used. 3.11.5 Total and ortho-phosphate phosphorus For total phosphate analysis, aliquots of 50 mL were preserved using sulphuric acid (H2SO4) to a pH less then 2, and then cooled to 4 °C for analysis within 28 days. The 38 samples were stored in plastic bottles. After block digestion (model BD-46, ATS Scientific Inc., Burlington, Canada), Standard Method 4500 P G was used for the determination of total phosphate (Clesceri et al., 1998). This involved the use of the flow injection analyzer that measures the blue phosphate complex that formed with the reagents under acidic conditions. In this experiment, the Lachat Quik-Chem 8000 flow injection analyzer was used. Samples for ortho-phosphate were preserved by adding one drop of phenyl mercuric acetate in approximately 10 mL of filtered sample. The same Standard Method 4500 P G was also used for the determination of ortho-P (Clesceri et al., 1998). 3.11.6 Nitrate-nitrite The cadmium reduction flow injection method (Standard Method 4500-NO3 - I) was used for nitrate-nitrite analysis (Clesceri et al., 1998). One drop of phenyl mercuric acetate was added in approximately 10 mL of filtered sample to preserve the sample for nitrate- nitrite analysis. Absorbance of the color at 540 nm was measured. For analysis, the Lachat Quik-Chem 8000 flow injection analyzer was used. 3.11.7 Total Kjeldhal nitrogen Total Kjeldhal nitrogen (TKN) is the sum of organic nitrogen and ammonium- nitrogen. For the preservation, the sample was acidified to pH 1.5-2 using sulphuric acid as a preservative and stored at 4°C. The nitrogen was measured, after block digestion, by flow injection analysis (Standard Methods #4500-N ORG D) (Clesceri et al., 1998). Digestion was done to recover nitrogen of organic origin. The apparatus used for the analysis was a Lachat block digester (model BD-46, ATS Scientific Inc., Burlington, Canada) and Lachat Quik- Chem 8000 Flow Injection Analyzer. 39 3.11.8 Total suspended solids Standard Method 2540 D was used for the determination of TSS (Clesceri et al., 1998). In essence, a well-mixed sample was filtered through glass micro-fiber filter papers (model 691, 4.7, VWR International, Inc., West Chester, USA) and then the residue retained on the filter was dried to a constant weight at 103 to 105°C. The weight of the residue represented the total suspended solids. 3.11.9 Capillary suction time To determine the rate of water release from the mixed liquor, samples were analyzed for CST. Standard Method 2710 G was followed to determine CST (Clesceri et al., 1998). The analysis was done just after sample collection, so no preservative was used. Mixed liquor sample was placed in a small cylinder on a sheet of chromatography paper (17 CHR, Whatman International Ltd, Maidstone, England) to do the CST test. Liquid from the mixed liquor was extracted by the paper through capillary action. Time in seconds, required for the liquid to travel a specified distance in the chromatography paper was recorded automatically by a CST testing apparatus (Capillary Suction Timer, KOMLINE-SANDERSON LIMITED, Brampton, Canada). 3.11.10 Time to filter Approximately 200 mL of mixed liquor sample was used to determine the TTF in accordance with Standard Method 2710 H (Clesceri et al., 1998). The test was done by placing the mixed liquor sample in a Buchner funnel on a glass fiber filter paper (G6, Fisher Scientific Company, Ottawa, Canada) under a constant 51 kPa vacuum. The time to filter value for a sample was the time required to filtre 100 mL of sample. The analysis was done immediately after the sample collection. 40 3.12 EPS Extraction and Quantification To characterize the relationship between the concentration of extra-cellular polymeric substances (EPS) and membrane fouling, EPS of aerobic mixed liquors were extracted and quantified. For the EPS analysis, mixed liquor samples were collected from the aerobic zones of both process trains and transferred immediately to the lab for EPS extraction. The extraction of EPS from mixed liquor was carried out using the cation exchange resin method (Frolund et al., 1996). The principal assumption of the method is that the EPS is mainly bound to cell aggregates through the bridging of divalent cations such as calcium and magnesium. Cation exchange resin (CER) can weaken the EPS matrix by removing these divalent metal ions from mixed liquor flocks and thus, EPS will be more easily released from biomass flocks into the liquid phase (Flemming et al., 2000). The procedure used for the EPS extraction was as follows. (1) Exactly 50 mL of activated sludge mixed liquor was centrifuged at 26,00 x g for 20 minutes at room temperature. The resulting supernatant was collected for unbound or soluble EPS measurement. (2) The centrifuged pellets were washed with about 50 mL of EPS extraction buffer (2 mM Na3PO4 , 4 mM NaH2PO4, 9 mM NaC1 and 1 mM KC1 at pH 7) by re-suspending the pellets in the buffer and centrifuging the suspension at 26,00 x g for 20 minutes. The supernatants produced in this step were decanted from the centrifuge tubes and discarded. (3) The washed mixed liquor pellets were transferred to 125- mL Erlenmeyer conical glass flasks after mixing with 15.0-20.0 mL of EPS extraction buffer. An additional 5 mL of the buffer was used to rinse each centrifuge tube and this was also transferred to the conical flask. (4) Cation exchange resin (DOWEX Marathon C, Na + - form, Sigma Aldrich) was measured and added to the flask in the ratio of 60 g CER/g SS. (5) To facilitate the cation exchange, the flask was placed on a refrigerated incubator shaker (New Brunswick Scientific, Edison, NJ, USA) for 2 hours at 400 rpm at 4 °C. (6) After agitation, the mixed liquor/CER mixture was immediately transferred to a centrifuge tube and centrifuged at 12,000 x g for 20 minutes at room temperature. The supernatant collected in this step was sampled for bound EPS analysis. All the mixed liquor samples were processed in triplicate. Soluble and bound EPS samples were stored at a temperature of - 20°C, if they were not analyzed immediately. For the analysis, the frozen samples were 41 thawed at 4 °C. Before analysis collected soluble and bound EPS samples were centrifuged at 12,000 x g for 5 minutes to remove any remaining flock components. The extracted bound and soluble EPS samples from the aerobic mixed liquors were analyzed for carbohydrates, proteins and humic-like substances. Colorimetric methods were used to quantify the EPS. The carbohydrate content of the extracts was analyzed by following the method suggested by Frolund et al. (1996) and the protein and humic-like substance contents of the extracts were analyzed by following the modified Lowry method (Frolund et aL, 1996). The concentration of carbohydrates in EPS was determined by the anthrone method, in which glucose was used as the standard (Frolund et al., 1996). Prior to the analysis, Anthrone reagent was prepared by dissolving 0.125% (w/v) anthrone in 94.5% (v/v) H2SO 4 . Once the anthrone was totally dissolved in the acid, 0.8 mL extracted EPS solution was mixed with 1.6 mL of the anthrone reagent. The mixture was then placed in an oven set at 100 °C, for 15 minutes. After removal from the oven, the mixture was then immediately put in a water bath at 4°C for 5 minutes for cooling. The absorbance of the mixture was measured at a 625 nm wavelength in a Hach DR2800 Direct Reading Spectrophotometer. The absorbance reading was corrected by subtracting the blind value due to the non-anthrone specific colour development. The blind value was estimated in the same way as above, except that the anthrone reagent was omitted. The modified Lowry method was used to quantify proteins and humic-like compounds, in which bovine serum albumin (BSA) and humic acids were used as the standards, respectively (Frolund et al., 1996). For this quantification, five reagents were prepared prior to the analysis. Reagent 1 contained 143 mM NaOH and 270 mM Na2CO3, Reagent 2 contained 57 mM CuSO 4 and Reagent 3 was a 124 mM Na-tartrate solution. Reagent 4 was prepared by mixing of Reagents 1, 2 and 3 in the proportion 100:1:1. To prepare reagent 5, Folin reagent was diluted with distilled water in the ratio of 5:6. When analyzed, 1.0 mL of EPS extract was mixed with 1.4 mL of Reagent 4 using a vortex mixer. Then 0.2 mL of Reagent 5 was mixed with the resulting solution using the vortex mixer and the mixture was left at room temperature for 45 minutes. Then, the absorbance of the mixture 42 was measured at 750 nm in a Hach DR2800 Direct Reading Spectrophotometer and was recorded as Atotal. In the Lowry procedure, proteins and humic compounds interfere with each other during the analysis (Frolund et al., 1996). When the mixture is prepared without the addition of reagent 2, the color development is due to humic-like compounds and chromogenic amino acids. In that case, the color developed by BSA decreased to 20%, as CuSO4 was absent, but no decrease was observed for humic acids. Therefore, the absorbance values for proteins and humic-like compounds were calculated using the following equations (Pattanayak, 2007). Atotal^Aproteins + Ahumic-like (3.4) Ablind = 0•2Aproteins + Ahumic-like (3.5) Aproteins = 1.25 (Atotal^Ablind) (3.6) Ahumic-like = Ablind — 0.2Aproteins (3.7) Where Atotal is the total absorbance value of the mixture with addition of CuSO4, Ablind is the total absorbance value of the mixture without addition of CuSO4, Anurnic-like is the absorbance value due to humic-like compounds, and Aproteins the absorbance value due to proteins. The concentrations of proteins and humic-like msfances an i  the EPS extract were calculated by fitting the values of Aproteins humic acids, respectively. 3.13 Critical Flux Test Assessment of the fouling propensity of activated sludge mixed liquor was done by the flux-step method, which determined the apparent critical flux of activated mixed liquor (Le Clech et al., 2003). The smaller the critical flux, the higher the potential of mixed liquor to foul membranes. As the critical flux depends upon the membrane module and the test configuration, in the present study, flux-step tests were done with the ZW-10 modules in the aerobic zones with the same setup and flow configuration as for the online filtration study. During the flux-step test, one test module in the aerobic zones was monitored as fluxes through those modules were increased every 30 minutes with an approximate increment of and Ahumic-like into the standard curves of BSA and 43 4.5 or 9 L/m2 •hr. At the start of the test, a low initial flux was kept constant for 30 minutes, then the flux was increased by approximately 9 L/m 2•hr., after which the system was operated in a constant flux mode again, and so on. TMP was closely monitored at 5 second intervals during the entire test period. When an increment in TMP was observed, the system was subjected to a smaller flux increment in the following steps i.e. approximately 4.5 L/m2•hr. The apparent critical flux was defined as the maximum flux, below which stable TMP is achieved and above which an increase in TMP with time is observed (Le Clech et al., 2003). To determine the value of critical flux, rate of change of TMP with time was plotted with respect to the permeate flux for that step. Generally at a low flux, the rate of change of TMP with time was relatively low. When the applied permeate flux was greater than the critical flux, the rate of change of TMP increased rapidly as the flux was further increased. For the present study, the critical flux was assumed to be equal to the intercept with the x- axis, of a linear relationship fitted to the rate of change in TMP observed at relatively high fluxes. 44 CHAPTER FOUR RESULTS AND DISCUSSION 4.1 Performance of the MEBPR Trains in the UBC Pilot Plant The present research study was conducted (in the UBC wastewater treatment pilot plant facility) between October 2006 and June 2007. The study was completed at two different SRTs, one of 20 days (1 to 185 operating day, Run SRT20) and one of 10 days (185 to 220 operating day, Run SRT10), while keeping the HRT at 10 hours. Two parallel MEBPR trains were operated. One train was subjected to a constant inflow (side-C) and the other train to a variable inflow (side-V). The source of the influent wastewater was the same for both trains as discussed in Section 3.1. The influent characteristics and the overall treatment performance of the two MEBPR trains are summarized in Table 4.1. Tables C.1 and C.2 in Appendix C summarize average data for all the performance parameters analyzed in the study. The day-to-day variation of the performance of both of the treatment trains is illustrated in Figures 4.1 to 4.9. The total mass of suspended solids (TSS) for the submerged membrane systems are shown in Figure 4.1. The average TSS in side-C and side-V was 8.4 (±0.6) kg and 8.1 (±0.5) kg respectively for Run SRT20. For Run SRT10, TSS in side-C was 5.4 (±0.5) kg and in side-V was 5.3 (±0.6) kg. The mass TSS in both trains were similar based on a 95% confidence interval. The TSS of both trains became relatively stable after running the MEBPR trains for about 20 days with 10 day SRT. The first 20 days of Run SRT10 represents a transition period between the 20 day SRT and the 10 day SRT operating conditions. Figure 4.2 illustrates the profile of the mixed liquor concentrations of anaerobic, anoxic and aerobic zones of both trains. The biomass concentration of side-C aerobic mixed liquor was 4.6 (±0.3) g/L in Run SRT20 and 3.0 (±0.3) g/L in Run SRT10. For side-V aerobic mixed liquor, the MLSS was 5.0 (±0.3) g/L and 3.3 (±0.3) g/L in the two runs, 45 respectively. A similar range of MLSS concentrations has been reported previously for this MEBPR process by Monti (2006) under similar operating conditions. Table 4.1. Influent and effluent characteristics and overall treatment performance of both of the MEBPR trains (side-C and side-V) at the UBC wastewater treatment pilot plant. Parameters Unit Run SRT 2 0 (Operating day 63 to 183) Run SRT 1 0 (Operating day 185 to 219) Effluent^EffluentInfluent C^V Effluent^EffluentInfluent C^V Total COD mg/L AverageStdev ^ 390.8^50.4^57.0 80.1^20.1^31.0 381.8^43.3^44.8 51.2^10.2 9.4 Soluble COD /Lmgt' Average 280.1^50.4^57.0 70.8^20.1^31.0 258.2^43.3^44.8 28.0^10.2 9.4 TKN itmg N' A"' Average Stdev 36.3 0.7 0.7 3.7^0.3^0.3 42.4 1.1^1.0 3.5^0.1 0.3 NH4-N it mg 1‘"j Average Stdev 32.0 0.3 0.1 6.0^0.6^0.3 39.3^0.03^0.1 9.2^0.03 0.1 NON-N a mg 1‘"-4 Average Stdev 0.1^13.2^16.5 0.1 2.6 3.3 0.1^13.9^15.4 0.1 3.3 2.1 TP n a mg A ' `-' Average Stdev 4.5^0.3^0.2 1.3 0.3 0.3 5.5^0.2^0.2 0.8 0 0 PO4-P off mg A ' A' Average Stdev 13.2^10.5^10.5 1.8 0.3 0.4 4.2^0.4^0.4 0.7 0.2 0.1 mg/L Average 28.9^ND^ND 31.8^ND^ND VFA (Acetic acid) Stdev 11.7 11.0 Temp. °C AverageStdev ^2 15.9^14.9^14.9 0.5 1.3 1.3 17.6^17.8^17.7 1.0 0.6 0.6 pH Average 7.1^7.2^7.2 7.1^7.2^7.1 Stdev 0.1 0.2^0.1 0.1 0.1 0.1 Note: The influent characteristics and the treatment performance were evaluated based on the mean values of the collected influent and effluent samples over days 63 to 183 for Run SRT20 and, days 185 to 219 for Run SRT10. ND - not detectable. average of operating days 150 to 183 2 average of operating days 163 to 183 46 Run SRT20 fi x• X 6000 • 5000 • 4000 as a) O • 3000 a a 0c.)^• § 2000 ^3"X-^X^ Cr^•^• 13^•^XW1000  x X. x 0 a • •• X XX  ̂ X X.—X— X ^ X•• • •x••t • •• x . x x xx X^X X X Run SRT10 • X X 4- • X 10 oR Run SRT10 0 60^80^100^120^140^160^180^200^220 Operating days Side-C^Side-V Figure 4.1. Total suspended solids (TSS) in side-C and side-V trains at UBC wastewater treatment pilot plant. 60^80^100^120^140^160^180^200^220 Operating days • Anaerobic C ■ Anoxic C A Aerobic C X Anaerobic V X Anoxic V • Aerobic V Figure 4.2. Mixed liquor concentrations in different zones of side-C and side-V trains. Run SRT20 47 •• Run SRT20 Run SRT10■ 500 600 20 19 18 17 E 15 I- 0 2 A 4 13 °T-4 12 60^80^100^120^140^160^180 Operating days ■ Influent^0 Aerobic C^A Aerobic V 14 Run SRT20 Run SRT10 200^220 Figure 4.3. Influent and effluent temperatures of side-C and side-V trains. • • ■^ ■ • ■ ■ ■^•^• • • ■ ■w o --. 400 o il o lo•-•••- ^•  • ^• • •— .-^.• • ■ 0 —.-.^■^■ . ■--^0 o n, 0 • o •■ ^IP •^0 o^ •^•^o^o 0^- ID^ o • o o OD ^ o •^• 1 o 0 0 0 ^^ ^ ^ 13 0 200^_coo 100 - • Aas^ "A^/A:0A AiA V • AAÂ A ^ri 00 0 A RAno 60^80^100^120^140^160^180 ^ 200 ^ 220 Operating days ^ Influent Soluble^■ Influent Total^0 Effluent C^A Effluent V cw • -- --- —E win % .^-9°0  o o • • • o • •  •^o •qv 0 13 o Ci • o °^o Figure 4.4. Total COD and filtered COD of influent and effluent of side-C and side-V trains. 48 ■ 2 -4 -3 ■ ^■ ■ Influent (left Y-axis) Operating days Effluent C (right Y-axis) A Effluent V (right Y-axis) 50 40 • ■l■ ■ ■▪ • •• ■ 30 ▪ • # • • • ■ • a,^■ it 20 Run SRT20 ti ■• • ■■ • ■ 6• Run SRT10 5 1 - •• • ■ .• A ---EZOO-trth^ilieCtarCOMO- o 180^200^220 10 0 60 80 100 140^160 ■ ■ 25 Run SRT20 • 5 M.  III .m•• • • s^•■ • • -% • ir.• 0^— mu • 60^80^100 Figure 4.5. Influent and effluent ammonium-nitrogen (NH4-N) concentrations of side-C and side-V trains. A ■ • ■ ■^• N E •• • •■• ■••• % .• ■ ■ • •^•• • 120^140^160 Operating days ^Effluent C (left Y-axis) ^ A Effluent V (left Y-axis) ^■ Influent (right Y-axis)  0.7 Run SRT10 - 0.6 A 180 - 0.2 • 0.1 ■ ■ ■• • • ••• ■ •^0 200^220 Figure 4.6. Influent and effluent nitrite plus nitrate nitrogen (NOx-N) concentrations of side- C and side-V trains. 49 ■ ■ • • A A^A • 4111^,g A 10 • •^• 4 ^A --a^A  iii_ —0'4 A •• A• di • III •^• 20^ • 70 60  ■ Run SRT20 Run SRT10 50 ■ ■ cri 40 • 0 60^80^100^120^140^160^180^200^220 Operating days ■ Influent^Anaerobic C^A Anaerobic V Figure 4.7. Influent and anaerobic zone mixed liquor VFA (as acetic acid) concentrations in side-C and side-V trains. 10 Run SRT20 Run SRT10 • cu E a 6 • ■ ■ 0 ■ ■^■ • 0 U N •mu ■^• ■ ■^■ • ■■^■■^■ # N-.• •^•^• ■• 1181AIli^wag^• J. • 2 ■• A 0 2 e;A(bt; • • A 0A,A ,„ A•A® 40 co < 30 ■^• ■ ■••• --•-■ ■ •• • ■ ■ • ■ ■ ■ ■ ■ 100 120^140^160 Operating days ■ Influent^Effluent C 180 A Effluent V 200 220 Figure 4.8. Influent and effluent ortho-P concentrations of side-C and side-V trains. 50 60.0 50.0 To' 40.0 a. I— 30.0 - 60.0 50.0 - 40.0 "E X - 30.0 LL O • 4te 40.- • *4,%•• • • Run SRT20 Run SRT10 %10 Side-V membrane cleaned at ♦• day 127 and day 135 A LA O ASioswe A Side-C flux decreased to reduce the rate of fouling 20.0 - 4. j0aeaow a 10.0 - 10.0 60^80^100^120^140^160^180^200^220 Operating days • Flux V A TMP C • TMP V a Flux C Figure 4.9. Operational membrane performance for side-C and side-V trains. It can be seen from Figures 4.1 to 4.9 that both MEBPR trains were performing well all through the study period. Table 4.1 shows that the average concentrations of total COD, total phosphorus, and total organic nitrogen (TKN) in effluents of both treatment trains were less than 60, 0.3 and 1.1 mg/L, respectively, in both Run SRT20 and Run SRT10. These values are close to those previously reported for the MEBPR process when operated under similar conditions (Monti, 2006). Figure 4.3 shows the steady increase in the influent and effluent temperatures with slight fluctuations over time. From Figure 4.4 it can be seen that both MEBPR trains were removing COD effectively in both Run SRT20 and Run SRT10. The calculated COD removal in each run ranged between 80 and 87 percent for both processes (calculation was based on the total influent COD and effluent COD). In the literature, a similar COD removal efficiency has been reported for other BNR processes (Hu et al,. 2003, Monti, 2006). There was an ammonium-nitrogen breakthrough between operating days 150 and 155 (Figure 4.5). Except for this period, ammonium-nitrogen was effectively removed in both trains which is indicated by very low ammonium-nitrogen 51 concentrations in the effluents of both trains. It should be noted that effluent of the train with variable inflow (side-V) contained more nitrite plus nitrate nitrogen (Figure 4.6) than the effluent from the train with constant inflow (side-C). This effect is probably because side-V contained less denitrifying biomass than side-C, as the biomass concentration in the anoxic zone of side-V was always less than that of side-C. The VFA concentration of the influent varied considerably, whereas VFA concentrations of the anaerobic zones of both trains were relatively stable (Figure 4.7). Except for a few days, the removal of phosphate was consistent with time (Figure 4.8). The effluent phosphate concentrations were in the same range for both of the MEBPR trains, as noted in the previous study at the same pilot plant facility when operated under similar conditions (Monti, 2006). The performances of the operating membrane (OM) modules in terms of flux and TMP are illustrated in Figure 4.9. The OM modules were operated under constant flux conditions throughout the study. There was an increase in TMP observed with time, which was similar to the TMP profile observed for these modules in a previous study (Geng, 2006). To reduce membrane cleaning frequency, the flux through the OM modules installed in side- C was reduced from 17 L/m2 •hr to approximately 12.6 L/m 2•hr on day 90, which successfully reduced the membrane fouling rate. This 12.6 L/m 2 •hr flux was enough to maintain the target 10 hour HRT in side-C. The Side-V train was operated with a variable inflow rate. This flow variation included a period (7 am to 1 pm) with a high inflow rate (Section 3.1). To maintain 10 hour HRT in side-V, the OM flux in that train was maintained at approximately 17 Um2•hr all throughout the study. The side-V OM modules were replaced with cleaned membranes at day 127, but the replaced modules fouled in less than 10 days (day 127 to 135). These modules were relatively old, and so they probably had significantly less effective surface area than specified. As a result, these modules may have been operated with a much higher flux than the nominal value, which might have resulted in the rapid fouling. A rapid fouling of the same set of modules was also observed previously in an earlier study (Fred Koch, Department of Civil Engineering, UBC, Vancouver, B.C., pers. comm.). It was decided that another set of OM modules should be installed in the side-V on day 135, and this set served the train until the end of the study. 52 The present study suggests that an MEBPR process with a varying influent (dynamic operating condition) performs similarly to an MEBPR process with steady operating conditions at SRTs of 10 days and 20 days. 4.2 Filtration Performance of the Test Membrane Modules in the MEBPR Trains Three filtration experiments (FE SRT20a, FE SRT20b, and FE SRT10a) were conducted with TM modules to characterize and compare membrane fouling under different operating conditions in the two parallel MEBPR trains (Section 3.3). Four TM modules were installed, two modules in the aerobic zones of both MEBPR trains (side-C and side-V) (Section 3.1.1 and Section 3.2). These four TM modules were numbered as #1, #2, #3 and #4 modules. It should be noted that although the #4 TM module never passed the membrane integrity test, it was always installed along with the other three TM modules to maintain similar hydrodynamic conditions in both trains. TMP data from the #4 module were not used for membrane filtration performance analysis. The first and second filtration experiments (FE SRT20a and FE SRT20b) were completed at a 20 day SRT and the third filtration experiment (FE SRT10a) was completed at a 10 day SRT. Pattanayak (2007) stated that the typical range of operating permeate flux is in the order of 15 to 30 L/m 2•hr for full-scale aerobic MBR systems treating municipal wastewaters. Therefore, for the present study, the permeate flux was set at 30 L/m2•hr for the TM modules during each filtration experiment. A moderately high flux was selected for the filtration experiments so that TM modules would be subjected to relatively quick fouling such that several filtration experiments could be completed within the allocated time for the study. The MLSS concentrations of the aerobic zones were different in the different filtration experiments (i.e. approximately 4650 to 5050 mg/L in FE SRT20a and FE SRT20b and, 2950-3250 mg/L in FE SRT10a). An individual filtration experiment was considered to be period of TM module operation between two sequential recovery chemical cleanings. For the present study, the TM modules were subjected to chemical cleaning when the TMP value reached approximately 50 kPa. The results from the filtration experiments are presented below. 53 side-C = reactor with constant inflow side-V = reactor with variable inflow Flux for each module was about 30 Um 2•hr 45 - Accidentally air sparging was reduced by 30 percent 35 ^ in #3 module 2 - 2 physical disturbance during the membrane removing operation might removed a portion of foulant accumulated on #1 module, resulted improve filtration performance vi dI • 4 Three TM modules marked as #1, #2 & #3 #1 in side-C #2 module installed in side-V #2 in side-V .4.444t, #1 in side-C 1 in side-C O 15 I#2 in side-C #2 in side-C 5 #3 in side-V For a 20 day SRT, the pilot plant was considered to have reached steady state after three months of operation. The first filtration experiment (FE SRT20a), was performed with the same flux (30 L/m2 •hr) in all TM modules, and was started on operating day 129. As noted above, four TM modules were installed in the aerobic zones of both trains: two (#1 and #2 module) in the train with constant inflow (side-C) and the other two (#3 and #4 module) in the train with variable inflow (side-V). TMP data for each TM module were collected almost continuously (one data point per minute). The overall filtration performances of these modules are illustrated in Figure 4.10. 55 FE SRT20a O^ ▪^ 00^N^CD co^ •^ 0^of^co^N^CD^O^et^CO CD 01^r^a CO CO r M CO CO er Filtration time (hours) Figure 4.10. The TMP profiles of the TM modules at the UBC pilot plant during the first filtration experiment (FE SRT20a). From Figure 4.10 it can be seen that from the start of filtration experiment FE SRT20a, the TMP of the #3 TM module increased more rapidly than those of the #1 and #2 modules. In addition to this, due to an operating accident near the 48 th hour of the filtration operation, the air sparging rate in the #3 module was reduced to 0.19 m 3/min from its target sparging rate of 0.28 m 3/min (Section 3.1.1), increasing the membrane fouling rate 54 significantly. As a result, the #3 module installed in side-V reached its maximum allowable TMP (62 kPa) within 96 hours of operation. Permeation through the #3 module was stopped at this point. On the other hand, the #1 and #2 modules installed in the train with constant loading fouled relatively slowly during the same period. After the 96th hour of filtration, there was no active TM module installed in side-V. At hour 155, the #3 TM module was removed from side-V and the #2 TM module was installed in side-V. Thereafter, both the #1 and #2 TM modules fouled at a relatively similar rate, which suggests that during time period in question, the mixed liquors of both trains exhibited similar fouling propensities. A second filtration experiment (FE SRT20b) was started on operating day 154 with the same MEBPR operating conditions as in FE SRT20a. The TM modules were operated under the same conditions as before (flux = 30 Um2•r and air sparging rate = 0.28 m3/min). In this second filtration experiment, the #1 and #2 TM modules were installed in the aerobic zones of side-V, and the #3 and #4 TM modules were installed in the aerobic zones of side-C (Figure 4.11). Figure 4.11 illustrates that during the first 48 hours of the second filtration experiment, the fouling rate of the # 2 TM module was unstable. This was due to the variable flow through that module, as the permeate pump serving the module was malfunctioning. As a result, average flow through the #2 TM module was lower than the target value. After replacing the pump, a stable flow (stable target flux of 30 Um 2•hr) through the module was achieved. As in FE SRT20a, an air sparging problem also occurred in FE SRT20b. This time the air sparging rate in the #1 TM module was reduced to fifty percent (0.14 m 3/min) of the target rate of 0.28 m 3/min (Section 3.1.1). As a result there, was a steep increase in TMP, and the #1 TM module became excessively fouled within 90 hours of filtration operation in the second filtration experiment. At that time the air sparging rate was returned to 0.28 m 3/min for the #1 TM module while the permeation was stopped. Shortly thereafter, permeation through the #1 TM module was started again and the TMP value was observed to be relatively low (Figure 4.11), which suggests that the foulant of the membrane had been removed (by air sparging) during the relaxation period. This indicates that the fouling that occurred in the #1 module was reversible, and it was assumed to have occurred mainly as a result of cake formation. As observed from the FE SRT20b experiment, the fouling propensities of the mixed liquors of both MEBPR trains were relatively similar. 55 Accidently air sparging was reduced by 40 percent in #1 module #2 in side-V 1#3 in side-C 15 I#3 in side-C 3 in side-C side-C = reactor with constant inflow side-V = reactor with variable inflow #2 in side-V Flux for each module was about 30 L/m 2•hr #1 in side-V 5° 03^N^COCO C*7 1 0^et^CO^N^CO^0^or N •0* tD Ch a— 'V c0 a—^,—^a—^e-^N^N^N Three TM modules marked as #1, #2 & #3 45 - 35 2 25 No permeation through #1 module 1#1 in side-V 55 FE SRT20b Filtration time (hours) Figure 4.11. The TMP profiles of theTM modules at the UBC pilot plant during the second filtration experiment (FE SRT20b). The third filtration experiment (FE SRT10a) was completed with a 10 day SRT in both MEBPR trains. For an SRT of 10 days, the pilot plant was considered to have reached steady state conditions after 20 days of operation. For FE SRT10a, the #1 TM module was installed in side-V and the #2 and #3 TM modules were installed in side-C, with the same fluxes (30 L/m2 •hr) and air sparging rates (0.28 m 3/min) used in the first two filtration experiments. As in the previous filtration experiments (FE SRT20a and FE SRT20b) the observed fouling rates of the TM modules of both sides (side-C and side-V) were also similar at a 10 day SRT (Figure 4.12). 56 55 FE SRT10a 45 Three TM modules marked as #1, #2 & #3 o 016,.,7's(-0..: • A>o''`o4W>tzt4,o^>K) #1 in side-V 15 - 5 0 ......., 35 co -1C a 2 I— 25 side-C = reactor with constant inflow side-V = reactor with variable inflow Flux for each module was about 30 L/m2•hr Filtration time (hours) Figure 4.12. The TMP profiles of the TM modules at the UBC pilot plant during the third filtration experiment (FE SRT10a). Figure 4.13, Figure 4.14 and Figure 4.15 illustrate the TMP profile of the #1, #2 and #3 TM modules in all three filtration experiments, respectively. It can be observed from these figures that the TMP of each TM module increased relatively slowly in the first two filtration experiments (FE SRT20a and FE SRT20b) when the MEBPR trains were running at a 20 day SRT, in comparison to the third filtration experiment (FE SRT10a) at a 10 day SRT. The more rapid fouling rate resulted in a shorter filtration experiment time for the third filtration experiment (75 to 85 hours), than in the first two filtration experiments (more than 430 hours). 57 55 45 35 - Fos a. I— 25 - #1 in side-C #1 in side-C • Filtration Experiment SRT20a o Filtration Experiment SRT20b Filtration Experiment SRT10a 5 0^24^48^72^96 120 144 168 192 216 240 264 288 312 336 360 384 408 432 Filtration time (hours) Figure 4.13. The TMP profiles of the #1 TM module during all three filtration experiments. 55^ 1 45^ #2 in side-C 3 l 5 - a' CL 25 #2 in side-V • Filtration Experiment SRT20a #2 in side-C o Filtration Experiment SRT20b Filtration Experiment SRT10a 5 0^24^48^72^96 120 144 168 192 216 240 264 288 312 336 360 384 408 432 Filtration time (hours) Figure 4.14. The TMP profiles of the #2 TM module during all three filtration experiments. 58 55 45 - I#3 in side-V 35 ea a. 2 I— 25 o Filtration Experiment SRT20b Filtration Experiment SRT10a 5 -- 0^24^48^72^96 120 144 168 192 216 240 264 288 312 336 360 384 408 432 Filtration time (hours) Figure 4.15. The TMP profiles of the #3 TM module during all three filtration experiments. 4.3 Fouling Propensity of the Activated Sludge Mixed Liquors From the preceding discussion, it is evident that the test membrane modules were fouled more quickly at a 10 SRT than at a 20 day SRT. On the other hand, the observed fouling rates of the TM modules were relatively similar when operated under either constant inflow or variable inflow conditions. Some physical (critical flux, CST, and time to filter) and biochemical properties (soluble and bound EPS) of the activated mixed liquor were analyzed in order to explore the key factors that influenced the fouling propensity of the mixed liquor. 59 4.3.1 Critical flux In the present study, critical flux, which is a parameter that reflects the fouling propensity of mixed liquor, was assessed twice during the whole study period. The first critical flux test was conducted on day 184 (at the 20 day SRT) and a second test on day 217 (at the 10 day SRT). As described in Section 3.12, the flux-step method was used to determine the critical flux of the aerobic mixed liquors of both trains. During the flux-step test, flux was increased every 30 minutes with the TM modules submerged in the aerobic zones of the MEBPR trains, while operating with the same setup and cyclic flow configuration as for the filtration experiments (Section 3.1.1 and Section 3.12). Typical results of the flux-step filtration tests are shown in Figure 4.16. 18 16 14 12 „4.004.•••'"••••""" 6 4 Assosamigigerivaa%  ♦ side-C^v side-V `'4(-44*kk4^‘ *00400W-W7. , 0^10^20^30^40^50^60^70^80^90^100 110 120 130^140 150 Filtration time (minutes) Figure 4.16. Results of flux-step filtration tests with aerobic mixed liquor of both trains (side- C and side-V) at a 20 day SRT. ---amme•■••••■•• From Figure 4.16, it can be seen that in each flux step there were three TMP profiles developed for each test membrane module, as there were three permeation and relaxation cycles in a 30 minute step period. Le-Clech et al. (2003) stated that the critical flux could be defined as the maximum flux, below which stable TMP is achieved and above which, an 60 350 • 57, 300 - co Ct 0- 250 --NC 0_2- 200 - 6 a) c 150 -co 0 is 100 - m Ce 50- 0^•^ • •• • •• increase in TMP with time is observed. To determine the average rate of change of TMP in a step, linear relationships were fitted to each of the TMP profiles observed in the flux-step test (Figure 4.16). The rates of change in TMP were then plotted with respect to the permeate flux for that step (Figure 4.17). As presented in Figure 4.17, at a low flux, the rate of change of TMP with time was relatively low. When the applied flux was greater than the critical flux value, the rate of change of TMP increased rapidly as the flux was further increased. These results are consistent with those from other studies which indicated that above the critical flux, fouling increases rapidly and linearly with respect to the difference between the critical flux and the applied flux (Field et al., 1995, Berube et al., 2007). For the present study, the critical flux was assumed to be equal to the intercept with the x-axis, of a linear relationship fitted to the rate of change in TMP observed at relatively high fluxes (Figure 4.18). Table 4.2 summarizes the values of critical fluxes for the both side-C and side-V trains at the 20 day and 10 day SRTs. 5^10^15^20^25 ^ 30 ^35 ^40 Flux ( Um2•hr) Figure 4.17. Rate of change of TMP vs. flux for critical flux analysis of data from the flux- step test of aerobic mixed liquor of side-C at 10 day SRT. 61 40353025 Flux (L/m2•hr) 10^15^20 300 la 0 0 2 200 - 0 C.) 45 100 ra 0 Linear regression fitted to the rate of change in TMP observed at relatively high fluxes Estimated value of critical flux Light lines are the 95% confidence interval for the regression line Upper 95% confidence limit on estimate Lower 95% confidence limit on estimate Figure 4.18. Critical flux calculation using data from the flux-step test of aerobic mixed liquor of side-C at a 10 day SRT. Table 4.2. Critical flux values for side-C and side-V for 20 day SRT and 10 day SRT. Operating condition Critical flux (L/m2•hr) Side-C Side-V Estimated value 95% confidence interval Estimated value 95% confidence interval min max min max 20 day SRT 23.8 11.6 28.8 19.4 -2.9 26.9 10 day SRT 20.8 18.3 22.5 19.7 8.8 23.8 As presented in Table 4.2 the estimated critical fluxes of the aerobic mixed liquors of both trains were relatively similar in both flux-step tests (values were tested against 5% level of significance). It was noted in the Section 4.2 that during the filtration experiments, the TM 62 modules were observed to foul more quickly at the 10 day SRT than at the 20 day SRT condition. It can be concluded that no clear relationship between critical flux and fouling propensity of the activated mixed liquor in submerged MEBPR trains could be discovered in the present study. 4.3.2 Capillary suction time Recently, the effect of capillary suction time (CST) on membrane fouling has become one of the focuses of attention of researchers (Khongnakorn et al., 2007; Ng et al., 2006; Wang et al., 2006; Wu et al., 2007). The CST parameter has been widely used for the evaluation of dewaterability of conventional activated sludge mixed liquors and usually, poor filterability and dewaterability of mixed liquor is indicated by a high value of CST (Wang et al., 2006). The normalized CST value, calculated by dividing the measured CST by its respective MLSS concentration, has been observed to be an indicator of the effect of mixed liquor on membrane filtration performance in an MBR (Ng et al., 2006). For the present study, mixed liquor samples were collected approximately two times per week from the aerobic zones of each MEBPR trains to measure capillary suction time to monitor dewaterability of the mixed liquor. Figure 4.19 and Figure 4.20 illustrate the CST and normalized CST over time during the present study period. As presented in the Figure 4.19, the CST values of the aerobic mixed liquors of both trains were relatively similar at SRTs of 10 days and 20 days. From Table 4.3 and Figure 4.20, it is evident that the normalized CST values for both aerobic mixed liquors were increased significantly when the SRT was decreased to 10 days from 20 days, which mirrored the reduced filtration performance of the test membranes under the 10 day SRT conditions (Section 4.2). On the other hand, normalized CST values for side-C and side-V were also significantly different in both runs (Run SRT20 and Run SRT10), even though the TM modules demonestrated similar rates of fouling in both trains (Section 4.2). No clear relationship between normalized CST and membrane fouling propensity of mixed liquor was observed in the present study. 63 80 70 - Upper error bar = maximum value Lower error bar = minimum value Average value = mean value n = 3 20 day SRT Transition period 10 day SRT 20 - - - Anaerobic-C —0-- Anaerobic-V 10 0.016 0.014 - U 1— u) co 0.012 - -0 nw 6 . 1 1 -0 To c 0.010 - E 8 8w z 'I' 0.008 - Upper error bar = maximum value Lower error bar = minimum value Average value = mean value n = 3 20 day SRT —0— Anaerobic-C —0— Anaerobic-V Transition period 10 day SRT 0.006 - 140^160^180 ^ 200 ^ 220 Operating Days Figure 4.19. Capillary suction time of aerobic mixed liquor during Run SRT20 and Run SRT10. 140^160^180 ^ 200 ^ 220 Operating Days Figure 4.20. Normalized capillary suction time of aerobic mixed liquor during Run SRT20 and Run SRT10. 64 Table 4.3. Normalized CST values for side-C and side-V for 20 day SRT and 10 day SRT. Operating condition Average normalized CST (second•L/mg) with 95% confidence interval in parenthesis Side-C Side-V 20 day SRT 0.0091 (±0.0007) 0.0068 (±0.0003) 10 day SRT 0.0122 (±0.0007) 0.0101 (±0.0006) 4.3.3 Time to filter In addition to capillary suction time, the parameter time-to-filter (TTF) is also used to measure the specific resistance of mixed liquor to filtration. In the TTF test, the time required to filter (under specific suction) a given volume of water through a cake of mixed liquor solids retained on a filter paper is measured (Merlo et al., 2004). For the present study, mixed liquor samples from the aerobic zones were collected approximately two times per week to measure TTF. The normalized TTF value was calculated by dividing the TTF value by its respective MLSS concentration. Table 4.4 summarizes the normalized TTF values for the present study. Table 4.4. Normalized TTF values for side-C and side-V for 20 day SRT and 10 day SRT. Operating condition Average normalized TTF (minute•L/mg) with 95% confidence interval in parenthesis Side-C Side-V 20 day SRT 0.0051 (±0.0006) 0.0038 (±0.0003) 10 day SRT 0.006 (±0.0003) 0.0036 (±0.0005) Figure 4.21 illustrates that, as for CST, the TTF values of the aerobic mixed liquors of both trains were relatively similar. As presented in Figure 4.22 and Table 4.4, there was no significant impact of SRT on the normalized TTF values. As the filtration performance of the test membranes (in the both MEBPR trains) declined in Run SRT10 relative to that of Run SRT20, (Section 4.2), it can be can be concluded that no clear relationship between 65 • • • • •_00 • • 20 - 22C200180160 20 day SRT 30 - Transition period 10 day SRT • • —ID— Anaerobic-C —0— Anaerobic-V 4•• ••10 - 0 140 • •• • 0.010 0.008 - 0.006 - • 0.004 - • 20 day SRT Transition period 10 day SRT —0— Anaerobic-C —0-- Anaerobic-V • • •• • 0.002 • • • normalized TTF and membrane fouling propensity of the activated mixed liquor in submerged MEBPR trains could be observed in the present study. 50 40 - Operating days Figure 4.21. Time to filter of aerobic mixed liquor during Run SRT20 and Run SRT10. 140 ^ 160^180^200 ^ 220 Operating days Figure 4.22. Normalized time to filter of aerobic mixed liquor during Run SRT20 and Run SRT10. U- 1— a) I— E -a :l-a • N (1)= w co 4-• E E 8 E Z 66 Run B 10 day SRT 80  I Upper error bar = maximum value Lower error bar = minimum value Average value = mean value n = 3 --0— Side-C —0— Side-V 60 - 40 - Run A 20 day SRT 4.3.4 Extracellular polymeric substances 4.3.4.1 Effects of EPS contents and membrane fouling The large number of publications in recent years dealing with the role of extra- cellular polymeric substances (EPS) in the fouling of membranes, indicates that the subject has attracted considerable attention from researchers (Le-Clech et al., 2006, Cho and Fane, 2002; Jarusutthirak and Amy, 2006; Ng et al., 2006, Rosenberger et al., 2006). Although these publications indicate that EPS components, including carbohydrates, proteins, and humic-like substances, play a major role in membrane fouling, the role of each of the compounds in the fouling formation is still to be clarified. Therefore, in the present study, the bound and the soluble carbohydrates, proteins and humic-like substances of the aerobic MEBPR mixed liquors of both sides were measured throughout the study. The summarized results of the analysis of bound carbohydrates, proteins, humic-like substances and total bound EPS for both of the mixed liquors are illustrated in Figure 4.23 to 4.26 respectively. Table 4.5 summarizes all the bound EPS data for both trains for SRTs of 10 days and 20 days. 0 120^140^160^180 ^ 200 ^ 220 Operating days Figure 4.23. Bound carbohydrate concentrations in aerobic mixed liquor during Run SRT20 and Run SRT10. 20 - 67 120 220180 200160140 80 60 - Upper error bar = maximum value Lower error bar = minimum value Average value = mean value n = 3 Transition period 40 - —ill— Side-C —0— Side-V 20 - 20 day SRT^I 10 day SRT 0 Transition period 10 day SRT o 220 I ̂ I^1 200120 140 160 180 Figure 4.24. Bound protein concentration in aerobic mixed liquor during Run SRT20 and Run SRT10. Upper error bar = maximum value Lower error bar = minimum value Average value = mean value n = 3 -AI— Side-C —0— Side-V 20 day SRT 80 Operating days Operating days Figure 4.25. Bound humic-like substances concentration in aerobic mixed liquor during Run SRT20 and Run SRT10. 68 120 100 - -0- Side-C 0^ Side-V z^80 - 44 W =r= Cf) o E-1 o ^60 - g o E4^40- Upper error bar = maximum value Lower error bar = minimum value Average value = mean value n = 3 20 - 20 day SRT Transition period 10 day SRT 140^160^180 0 120 200 ^ 220 Operating days Figure 4.26. Total bound EPS concentration in aerobic mixed liquor during Run SRT20 and Run SRT10. Table 4.5. Bound EPS concentrations for side-C and side-V for SRTs of 20 days and 10 days. Component of bound EPS Average concentration (mg/g TSS) with 95% confidence interval in parenthesis side-C side-V 20 day SRT 10 day SRT 20 day SRT 10 day SRT Carbohydrate 9.2 (±1.2) 19.9 (±2.6) 7.4 (±1.3) 9.2 (±2.7) Protein 31.7 (±1.2) 46.7 (±7.9) 23.1 (±1.7) 40.7 (±5.5) Humic-like substances 2.9 (±1.1) 32.0 (±5.3) 2.3 (±1.0) 48.0 (±3.8) Total Bound EPS 42.3 (±2.9) 98.7 (±6.2) 33.0 (±2.2) 97.9 (±8.9) Figure 4.26 illustrates the total amount of EPS bound in the floc of mixed liquors of both MEBPR trains. It appears that the aerobic mixed liquors of both trains contained greater amounts of bound EPS at an SRT of 10 days than at an SRT of 20 days (Figure 4.26 and Table 4.5). This increase in bound EPS content is consistant with the observed increase in 69 aerobic mixed liquor fouling propensity in both trains in Run SRT10 (Section 4.2). This suggests that there is a relationship between the content of bound EPS in the mixed liquor and the membrane performance and hence the content of bound EPS might be a key property to predict the fouling propensity of activated sludge mixed liquor. Figure 4.23 and Table 4.5 illustrate that the bound carbohydrate concentrations were almost the same in both runs (Run SRT20 and Run SRT10) in side-V and slightly higher for side-C in Run SRT10, suggesting that there is no clear relationship between bound carbohydrate concentrations and membrane fouling. Figure 4.24 shows that bound protein increased slightly in both of the trains in Run SRT10. It can be suggested from Figure 4.25 and Table 4.5 that the mixed liquors from both trains in Run SRT10 contained significantly higher concentrations of bound humic-like substances than in Run SRT20. These results suggest that the concentration of specific components (protein and humic-like substances) of bound EPS may play an important role in the membrane fouling of aerobic membrane bioreactors. The soluble carbohydrate, slouble protein, soluble humic-like substances and total soluble EPS concentrations are summarized in Figures 4.27 to 4.29 and in Table 4.6. These figures indicate that the amounts of soluble EPS present in the aerobic mixed liquors of both trains were comparable throughout the study. Figure 4.27, Figure 4.28 and Table 4.6 illustrate that the of soluble protein concentrations did not change significantly from Run SRT20 to Run SRT10 and there was a slight decrease in soluble carbohydrate concentrations. From Table 4.6, it can be seen that there was a significant increase of the concentration of soluble humic-like substances of MEBPR mixed liquor in Run SRT10 as compared to Run SRT20 (Figure 4.29 and Figure 4.30). This suggests that the content of soluble humic-like substances in the mixed liquor may have been related to the membrane fouling. 70 20 - 0 Upper error bar = maximum value Lower error bar = minimum value Average value = mean value n = 3 60 - —0— Side-C —0— Side-V Transition period 10 day SRT 80 20 day SRT 80 Upper error bar = maximum value Lower error bar = minimum value Average value = mean value n = 3 -AI— Side-C —0— Side-V 40 - 20 day SRT Transition period 10 day SRT 120^140^160^180^200^220 60 - 120 ^ 140 ^ 160 ^ 180 ^ 200 ^ 220 Figure 4.27. Soluble carbohydrate concentration in aerobic mixed liquor during Run SRT20 and Run SRT10. Operating days Figure 4.28. Soluble protein concentration in aerobic mixed liquor during Run SRT20 and Run SRT10. 71 220 80 Upper error bar = maximum value Lower error bar = minimum value Average value = mean value n = 3 20 day SRT —0— Side-C —0— Side-V Transition period 0 120 Operating days 180 120 100 - Upper error bar = maximum value Lower error bar = minimum value Average value = mean value n = 3 z^80 - A* P4 cw ..0 .4 3 = il6 0 - E Ti-,... 0 E•^40- 20 - 20 day SRT 10 day SRT 0 I^ 120^140^160^180 200 220 --0— Side-C —0— Side-V Transition period Figure 4.29. Soluble humic-like substances concentration in aerobic mixed liquor during Run SRT20 and Run SRT10. Operating days Figure 4.30. Total soluble EPS concentration in aerobic mixed liquor during Run SRT20 and Run SRT10. 72 Table 4.6. Soluble EPS concentrations for side-C and side-V for SRTs of 20 days and 10 days. Component of soluble EPS Average concentration (mg/L) with 95% confidence interval in parenthesis side-C side-V 20 day SRT 10 day SRT 20 day SRT 10 day SRT Carbohydrate 15.7 (±2.2) 9.4 (±1.2) 16.1 (±2.3) 6.3 (±1.6) Protein 7.0 (±2.5) 10.3 (±1.1) 13.4 (±7.6) 10.7 (±1.2) Humic-like substances 2.3 (±0.5) 17.9 (±1.0) 2.3 (±1.3) 16.2 (±1.1) Total Soluble EPS 25.1 (±1.5) 37.7 (±1.0) 29.6 (±8.5) 33.2 (±1.5) 4.3.4.2 Effect of operating conditions on EPS production The total EPS concentrations of the aerobic mixed liquors of side-C and side-V are shown in Figure 4.31 and Figure 4.32, respectively. From both of these figures it is evident that the bound EPS constitutes the majority of the total EPS in both trains during both runs. From Figure 4.33 it can be seen that the total EPS concentrations were almost the same for both the mixed liquors, although the total EPS concentration was higher in Run SRT10. Although several publications have indicated that EPS production increases with variable organic and hydraulic loading in a relatively small-scale (25 to140 L) biological wastewater treatment train (Drews et al., 2005; Evenblij et al., 2005), in the present study no significant difference in the concentration of EPS components in the aerobic mixed liquors of side-C and side-V were observed (Figure 2.28 to 4.33). Therefore, it can be concluded that the range of variable loading used in the present study did not have any significant impact on EPS production in a relatively large-scale (2200 L) MEBPR process. From Figure 4.33 it is clear that both MEBPR trains produced significantly higher levels of total EPS in Run SRT10, relative to the Run SRT20. Other researchers have also reported that a clear increase of EPS level was observed at shorter SRT (Ng et al., 2006, Rosenberger et al., 2006; Jarusutthirak and Amy, 2006). Therefore, the lower SRT in Run SRT10 might be a contributor to the higher production of EPS and thus, a higher fouling 73 1000 800 - cc ...et^600 -L ta) = cdo og 400 - a ;.14 c 1^200 -. 0 0- —0— Total Bound EPS —0— Total Soluble EPS —v— Total EPS Upper error bar = maximum value Lower error bar = minimum value Average value = mean value n = 3 0 - - - 0  - 0^ 20 day SRT Transition period 10 day SRT propensity of the aerobic mixed liquors, ultimately causing a higher rate of fouling of the membranes. 120^140^160^180 ^ 200 ^ 220 Operating days Figure 4.31. Concentration of total EPS in aerobic mixed liquor of side-C during Run SRT20 and Run SRT10. 200 1000 = 0• m ••■eet6 n 600 -cu 4O TA CJ E Ci W 400 - 3 0 800 - 200 - 0 —0— Total Bound EPS —0— Total Soluble EPS —v— Total EPS Upper error bar = maximum value Lower error bar = minimum value Average value = mean value n = 3 20 day SRT Transition period 10 day SRT  120^140^160^180^ 220 Operating days Figure 4.32. Concentration of total EPS in aerobic mixed liquor of side-V during Run SRT20 and Run SRT10. 74 1000 800 - —III— Side-C —0— Side-V Upper error bar = maximum value Lower error bar = minimum value Average value = mean value n = 3 200 - 20 day SRT Transition period 10 day SRT 0 120^140^160^180 220200 Operating days Figure 4.33. Total EPS concentration in aerobic mixed liquor during Run SRT20 and Run SRT10. 75 CHAPTER FIVE CONCLUSIONS The following conclusions were made on the results obtained from the present study of the submerged MEBPR processes at the UBC wastewater treatment pilot plant facility. 1. Both of the MEBPR processes (one with constant inflow and another with variable inflow, named as side-C and side-V respectively) were effective in removing COD, VFA and P, and also, they were capable of achieving complete nitrification. 2. The observed fouling rates of the test membrane modules were similar in the parallel MEBPR trains (side-C and side-V) under both sets of operating conditions applied (SRTs of 10 days and 20 days). On the other hand, the test membrane modules fouled more quickly during operation at a 10 day SRT than at a 20 day SRT. This suggested that the fouling propensities of the MEBPR mixed liquors were similar in both parallel trains under the operating conditions applied, although the fouling propensity of the aerobic mixed liquors of both trains increased when SRT of the trains was reduced. 3. The critical fluxes of the aerobic mixed liquors of both MEBPR trains were similar during the experiments and no clear impact of SRT on critical flux was observed. 4. For both MEBPR trains, the capillary suction time (CST) values of the aerobic mixed liquors were similar under all applied operating conditions. Normalized CST values for both aerobic sludge mixed liquors increased when the SRT was decreased. On the other hand, normalized CST values of both MEBPR trains were significantly different in both runs (Run SRT20 and Run SRT10). 5. As for critical flux and CST, time-to-filter (TTF) values of the aerobic mixed liquors of both MEBPR trains were relatively similar. The normalized TTF values for the aerobic mixed liquor of both trains remained similar when the MEBPR processes were operated at different SRTs. 6. The results suggest that the increased concentrations of specific components (protein and humic-like substances) of bound EPS may have been associated with the 76 observed increased membrane fouling rate. A similar association of soluble humic- like substances concentrations with membrane fouling rate was also observed. 7. The results of the present study shows that there was an increase in the concentration of EPS, particularly the bound protein, bound and soluble humic-like substances, with a decrease in SRT of the MEBPR processes. 8. The bound, soluble and total EPS contents of the aerobic mixed liquors were similar in the parallel MEBPR trains under both operating conditions, which indicates that flow variation in an MEBPR process did not make a significant difference in EPS production under the operating conditions applied. An MEBPR process with a varying influent is capable of performing similarly to an MEBPR process with steady operating conditions. It has been observed that the fouling propensity of an activated sludge mixed liquor in an MEBPR process with or without transient (dynamic) operating conditions increases with a decrease in SRT. The results of the present study suggest that the content of bound protein, as well as bound and soluble humic- like substances in the activated sludge mixed liquors, may be related to the membrane fouling. No clear relationships between parameters such as critical flux, normalized CST and normalized TTF and the membrane fouling propensity of mixed liquors were observed in the present study. It can be concluded that the range of transient loading (dynamic operation) used in the present study did not have any significant impact on fouling propensity of the activated sludge mixed liquors of the MEBPR processes. 77 CHAPTER SIX RECOMMENDATIONS Although the present research addressed membrane fouling with different operating conditions in MEBPR processes, the study generated new research questions that could not be addressed within the allocated time or were beyond the scope of this research work. There are still research needs that need to be carried out in the future to improve our knowledge about membrane fouling in the MEBPR-like processes. Based on the experience gained from this study the following recommendations about future research were made. 1. The present study was conducted with only one flow fluctuation pattern. The ratio of the peak inflow to daily average inflow was about 1.6 and there were only one high flow and one low flow condition in that flow fluctuation pattern. However, the wastewater flow variation patterns observed at full-scale wastewater treatment plants normally have two peak flows and two minimum flows and the variation between the high and low flows depends mainly on the community size served by a treatment plant (Tchobanoglous, 2003). More research can be conducted with other flow fluctuation patterns and rates to get a complete picture of the effect of loading variation on membrane fouling in MBR processes. 2. In the present research work, the MEBPR process was studied only under variable flow conditions. Typically full-scale wastewater treatment plants undergo other operating transients, i.e., short term changes in dissolved oxygen concentration, wastewater temperature, or pH. Therefore, a study of the effect of these short term changes on membrane fouling is quite necessary for a complete evaluation of the membrane fouling phenomenon in an MBR process under dynamic conditions. 3. In the present membrane fouling study, operating permeate flux was set above the critical flux. It has been reported in the literature that, if operating permeate flux was set well below the critical flux, that low flux operation can offer scope to reduce the membrane fouling (Le-Clech et al., 2006). The economic viability of the current generation of MBRs depends on selecting an appropriate permeate flux to obtain the 78 best compromise between flux and TMP and to reduce the rate of fouling. It is thus necessary to conduct a research study with operating flux below critical flux to see is there any impact of dynamic operating condition on membrane fouling when the membrane are fouling slowly. 4. The test membrane module used in this study was much smaller than the typical full scale membrane module used in full scale wastewater treatment plants. On the other hand, membrane fouling depends on the hydrodynamic conditions around a membrane module, which are closely related to the size and shape of the membrane module installed. To address this, a study should be carried in the future with full scale membrane modules with dynamic operating conditions in MBRs. 5. In this study, EPS was thought to be one of the potential foulants and the production of EPS depends on the operating conditions applied. It is thus necessary to initiate a research study to find the operating conditions under which less EPS is produced in an MBR process. 6. 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Operational data for Run SRT20 (Operating day 63 to 183) influent effluentC effluent V anaerobic C anaerobic V anoxic C anoxic V aerobic C aerobic V TSS mg/L Average 1556.8 1017.9 3298.2 2144.2 4645.3 5041.7Stdev 351.6 276.6 348.8 285.8 371.3 266.7 COD (total) mgt' Average 390.8 50.4 57.0 80.1 20.1 31.0 COD soluble mg /L Average 280.1 50.4 57.0 Stdev 70.8 20.1 31.0 TKN mg N/L Average 36.3 0.7 0.7Stdev 3.7 0.3 0.3 N H4 -N mg N/L Average 32.0 0.3 0.1 20.0 25.5 9.6 16.6 0.3 0.2Stdev 6.0 0.6 0.3 2.8 4.8 2.4 3.7 0.2 0.3 NON-N mg N/L Average 0.1 13.2 16.5 0.1 0.1 3.4 0.6 13.5 16.1Stdev 0.1 2.6 3.3 0.1 0.1 1.1 0.4 3.0 3.3 TP mg P/L Average 4.5 0.3 0.2Stdev 1.3 0.3 0.3 PO4-P mg P/L Average 3.2 0.5 0.5 15.9 12.5 6.7 8.1 1.2 1.3Stdev 1.8 0.3 0.4 1.9 3.1 3.3 3.3 2.3 2.6 VFA mg/L (as Acetic acid) Average 28.9 ND ND 8.2 14.5 Stdev 11.7 2.4 5.0 Temp. °C Average 15.9 14.9 14.9 14.85 14.9Stdev 0.5 1.3 1.3 1.3 1.3 PH Average 7.1 7.2 7.2Stdev 0.1 0.2 0.1 DO mg/L Average 2.6 2.6Stdev 0.3 0.4 Table C.2. Operational data for Run SRT10 (Operating day 185 to 219) influent effluentC effluent V anaerobic C anaerobic V anoxic C anoxic V aerobic C aerobic V TSS mgt, Average 1081.1 715.6 2202.2 1483.3 2966.4 3259.1 Stdev 88.5 139.1 240.2 162.1 302.0 316.3 COD (total) mgmgt Average 381.8 43.3 44.8 Stdev 51.2 10.2 9.4 COD soluble mg/L Average 258.2 43.3 44.8 Stdev 28.0 10.2 9.4 TKN mg N/L Average 42.4 1.1 1.0Stdev 3.5 0.1 0.3 NH 4 -N mg N/L Average 39.3 0.03 0.1 24.0 24.8 9.5 16.5 0.2 0.3Stdev 9.2 0.03 0.1 2.0 9.6 4.8 7.9 0.2 0.2 NON-N mg N/L Average 0.1 13.9 15.4 0.1 0.1 2.0 0.5 14.2 15.9Stdev 0.1 3.3 2.1 0.1 0.1 0.6 0.2 3.6 2.1 TP mg P/L Average 5.5 0.2 0.2Stdev 0.8 0 0 PO4-P mg P/L Average 4.2 0.4 0.4 12.5 9.0 3.0 5.1 0.3 0.4Stdev 0.7 0.2 0.1 0.8 1.2 0.9 2.5 0.1 0.1 VFA mg/L (as Acetic acid) Average 31.8 ND ND 11.2 13.6 Stdev 11.0 3.3 2.8 Temp. °C Average 17.6 17.8 17.7 17.8 17.7Stdev 1.0 0.6 0.6 0.6 0.6 pH Average 7.1 7.2 7.1 Stdev 0.1 0.1 0.1 DO mg/L Average 2.6 2.6Stdev 0.1 0.1 APPENDIX D: MONITORING RECORDS MONITORING RECORDS (In CD-ROM) 97 COD tot COD sol P tot PO4-P TKN NH4-N NOx-N VFA T pH COD sol P tot PO4-P TKN NH4-N NOx-N COD sol P tot PO4-P TKN NH4-N NOx-N PO4-P NH4-N NOx-N VFA TSS PO4-P NH4-N NOx-N TSS P tot PO4-P TKN NH4-N NOx-N TSS Flux TMP T DO PO4-P NH4-N NOx-N VFA TSS PO4-P NH4-N NOx-N TSS P tot PO4-P TKN NH4-N NOx-N TSS Flux TMP T DO mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L oC mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L L/m2 .hr kPa oC mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L L/m2 .hr kPa oC mg/L Operating day Date 63 1-Jan-07 39.2 0.0 41.3 42.4 0.1 13.0 65.6 0.1 20.4 12.9 0.0 8.0 4.9 2.2 0.1 7.8 17.6 26.1 2.5 14.8 0.0 9.8 8.4 0.3 0.1 10.0 17.6 32.8 2.5 64 2-Jan-07 282.0 197.8 3.9 32.8 24.6 0.1 16.4 42.4 0.0 0.5 0.1 8.0 42.4 0.1 0.8 0.1 10.0 1320.0 2840.0 210.0 340.0 3840.0 17.6 28.1 13.4 2.4 1070.0 2050.0 226.0 360.0 17.4 35.6 13.3 2.6 65 3-Jan-07 288.3 156.9 32.3 0.1 18.6 7.1 65.6 0.1 7.8 65.6 0.1 11.5 19.2 28.1 2.5 17.6 34.9 2.5 66 4-Jan-07 332.1 241.3 33.3 0.1 19.3 30.9 0.1 10.3 33.7 0.4 15.1 18.7 0.1 6.4 6.8 2.5 0.1 10.0 17.6 24.7 2.5 22.1 0.0 7.4 17.2 0.2 0.1 13.4 17.6 2.5 67 5-Jan-07 413.4 238.2 4.7 36.0 0.0 22.6 7.0 45.3 0.1 0.4 0.1 9.9 36.6 0.1 0.5 0.1 11.7 2340.0 2990.0 206.0 354.0 3740.0 17.6 24.7 12.9 2.5 750.0 1910.0 236.0 405.0 4300.0 17.6 33.2 13 2.6 68 6-Jan-07 288.3 329.0 31.2 0.1 17.5 6.9 25.1 0.1 11.1 54.0 0.0 13.4 17.6 25.1 13.1 2.5 17.6 32.8 12.6 2.5 69 7-Jan-07 319.6 244.5 19.7 0.1 12.6 7.1 0.1 6.9 42.4 0.0 9.7 17.6 26.1 12.8 2.7 17.6 33.2 12.9 3.6 70 8-Jan-07 438.5 194.4 25.1 0.2 26.7 39.5 0.1 8.6 80.1 0.1 11.5 17.6 25.4 2.3 17.6 33.2 2.5 71 9-Jan-07 32.3 17.6 27.1 14.2 3.2 17.6 33.2 14.3 2.7 72 10-Jan-07 329.0 191.3 30.7 0.1 7.2 33.7 0.1 6.3 0.1 16.7 17.6 25.7 13.4 2.4 17.6 32.8 13.2 2.5 73 11-Jan-07 510.3 375.9 7.6 43.2 31.2 0.1 7.1 80.1 0.1 0.6 0.7 15.4 85.9 0.1 0.5 0.1 19.6 1520.0 2940.0 228.0 519.0 4360.0 17.6 26.8 1020.0 2100.0 233.0 369.0 4740.0 17.6 32.5 74 12-Jan-07 497.9 206.9 34.4 0.3 7.1 30.9 0.1 16.5 42.4 0.0 21.0 20.7 0.1 9.5 5.0 0.1 21.6 17.6 25.1 2.5 27.7 0.1 23.4 1.0 0.1 17.6 32.8 2.2 75 13-Jan-07 410.3 34.1 0.1 71.4 0.1 16.2 56.9 0.1 21.2 17.6 25.4 12.9 2.6 17.6 32.5 12.9 2.5 76 14-Jan-07 513.6 388.4 34.2 0.4 51.1 0.1 16.1 68.5 0.1 20.5 17.6 25.7 12.8 2.5 17.6 33.2 12.3 2.5 77 15-Jan-07 510.6 397.8 38.1 0.1 45.4 7.1 0.1 14.4 0.1 19.4 24.2 0.3 7.1 10.3 3.5 0.1 13.9 17.6 24.7 2.2 33.1 0.1 23.3 22.4 0.1 0.1 19.5 17.6 33.2 2.5 78 16-Jan-07 529.2 363.4 38.4 0.0 47.8 7.2 0.1 13.1 42.4 0.0 18.0 1750.0 3400.0 4910.0 17.6 28.8 840.0 1900.0 5200.0 17.6 33.9 79 17-Jan-07 460.4 397.8 37.9 0.0 44.6 7.0 51.1 0.0 12.4 0.0 18.5 17.6 27.1 13.2 2.5 17.6 34.2 13.1 2.7 80 18-Jan-07 497.9 310.2 37.9 0.1 23.0 7.1 39.5 0.0 11.8 65.6 0.0 15.3 19.9 0.3 8.9 4.2 0.1 13.6 17.6 34.2 12.9 2.4 24.3 0.1 10.5 15.4 0.8 0.1 17.0 17.6 35.2 12.5 2.1 81 19-Jan-07 400.9 307.1 31.6 0.0 32.7 7.2 33.7 0.0 12.0 65.6 0.1 14.6 760.0 3380.0 4760.0 17.6 32.2 12.6 2.5 1230.0 2480.0 5050.0 17.6 35.9 12.7 2.4 82 20-Jan-07 310.2 247.6 28.2 0.0 26.7 7.0 54.0 0.1 10.1 48.2 0.0 14.5 17.6 35.2 2.5 17.6 35.6 2.5 83 21-Jan-07 466.6 360.2 34.8 0.1 23.9 7.3 42.4 0.1 13.9 0.0 17.7 17.6 32.5 13.7 2.5 17.6 35.9 13.5 2.7 84 22-Jan-07 391.5 282.0 40.1 0.2 24.5 6.9 91.6 0.1 15.2 88.8 0.0 19.1 17.6 32.5 13.1 2.6 17.6 36.2 12.9 2.7 85 23-Jan-07 222.6 7.7 31.4 7.1 68.5 0.1 0.3 0.0 7.9 68.5 0.1 0.4 0.0 9.5 0.1 1580.0 4.8 2.3 3180.0 227.0 408.0 0.1 7.6 4700.0 17.4 46.7 12.9 4.0 0.3 4.8 740.0 9.0 0.3 2010.0 258.0 433.0 0.1 9.3 5080.0 17.4 38.3 13.2 6.0 86 24-Jan-07 253.9 163.1 17.3 0.4 68.5 0.0 9.4 62.7 0.0 10.9 17.1 44.0 3.1 4.0 87 25-Jan-07 397.8 313.3 31.0 12.9 7.1 48.2 0.1 12.2 62.7 0.0 14.8 17.4 44.7 12.9 2.5 13.1 2.5 88 26-Jan-07 347.7 278.9 4.1 35.0 28.8 0.0 23.0 7.3 80.1 0.1 0.7 0.0 14.8 0.6 0.6 0.0 18.5 19.9 0.2 5.9 9.6 5.1 0.1 14.9 17.4 48.1 13.1 2.5 26.4 0.1 15.1 19.0 0.8 0.2 17.6 40.6 13.8 2.4 89 27-Jan-07 444.7 341.5 31.3 0.1 29.1 7.1 59.8 0.1 15.2 0.0 18.6 17.1 45.7 2.3 17.6 2.5 90 28-Jan-07 397.8 332.1 32.7 0.0 31.2 7.0 59.8 0.1 14.4 114.8 0.1 17.5 17.1 33.5 2.5 17.6 39.6 2.3 91 29-Jan-07 466.6 35.8 0.0 24.6 7.1 85.9 0.1 15.0 45.3 0.0 16.8 21.8 0.0 9.7 5.0 0.3 14.7 12.6 38.6 12.6 2.3 29.9 0.0 19.8 0.1 0.2 16.8 17.6 39.3 12.7 2.7 92 30-Jan-07 422.8 357.1 33.8 0.0 24.6 7.3 39.5 0.1 15.8 59.8 0.2 18.3 13.8 17.6 13.9 93 31-Jan-07 294.5 4.3 37.3 35.1 0.0 35.2 103.2 1.0 1.1 0.1 15.8 83.0 0.8 1.0 0.0 20.0 12.1 2.3 2.5 94 1-Feb-07 444.7 322.7 36.8 0.0 36.8 7.2 39.5 0.0 16.7 45.3 0.0 21.0 23.0 0.1 6.1 9.2 5.7 0.8 15.9 14.7 2.5 28.3 0.0 17.0 17.4 1.2 0.1 20.0 17.6 40.6 14.8 2.5 95 2-Feb-07 501.0 422.8 36.6 0.0 28.3 7.1 45.3 0.1 16.1 71.4 0.1 20.3 1490.0 3070.0 4560.0 12.1 14.1 2.5 630.0 1910.0 4870.0 17.6 39.6 14.3 2.6 96 3-Feb-07 37.6 0.1 40.7 42.4 0.1 17.0 39.5 0.0 21.4 17.6 42.0 97 4-Feb-07 12.1 14.2 17.6 41.0 14.1 98 5-Feb-07 389.1 310.4 39.7 0.1 48.1 7.0 80.1 0.1 15.0 51.1 0.1 19.0 13.7 2.5 17.6 40.6 13.8 2.5 99 6-Feb-07 5.1 34.2 36.0 0.0 43.0 7.1 0.8 1.0 0.1 14.0 0.9 1.1 0.0 20.0 2.4 17.6 41.0 2.5 100 7-Feb-07 565.4 291.3 7.4 33.0 0.6 22.7 7.3 56.9 4.1 0.1 14.0 126.4 3.9 0.8 19.9 0.1 2.4 14.9 12.4 19.6 2.3 0.1 0.4 20.3 17.6 41.7 2.5 101 8-Feb-07 6.9 12.1 19.6 13.8 2.6 17.6 41.3 13.9 2.5 102 9-Feb-07 8.0 36.0 0.0 7.1 4.4 0.2 16.0 4.7 0.0 20.6 12.1 21.0 14.3 2.6 17.6 42.3 14.4 2.6 103 10-Feb-07 2.6 0.5 7.2 0.3 0.5 8.7 0.3 0.0 9.6 12.1 20.7 14.2 2.5 17.6 42.3 14.1 2.7 104 11-Feb-07 2.9 18.4 0.3 0.3 0.0 7.7 0.3 0.0 8.4 12.6 18.6 14.4 17.6 43.0 14.3 105 12-Feb-07 369.6 285.1 3.5 40.0 67.6 7.5 51.1 0.1 0.7 68.5 0.0 0.6 1600.0 3330.0 5030.0 12.6 19.6 2.6 15.3 840.0 2230.0 5580.0 17.6 44.0 2.5 106 13-Feb-07 12.6 22.0 15.0 2.5 17.6 44.7 15 2.4 107 14-Feb-07 7.2 12.6 24.0 15.1 2.7 15.2 2.4 108 15-Feb-07 338.3 185.0 7.1 59.8 184.3 12.6 23.4 3.4 0.0 2.5 109 16-Feb-07 191.3 160.0 12.6 7.1 50.1 94.4 12.6 26.1 16.0 3.6 17.1 44.0 15.2 2.4 110 17-Feb-07 12.6 30.5 15.1 3.0 17.1 44.7 15.3 2.6 111 18-Feb-07 12.6 19.3 17.1 45.4 112 19-Feb-07 410.2 260.1 1.5 30.3 0.0 7.1 0.5 1.2 13.8 0.2 0.0 17.6 12.6 20.0 15.7 2.5 17.1 47.4 15.9 2.5 113 20-Feb-07 12.6 20.0 2.5 17.1 47.7 2.5 114 21-Feb-07 7.3 12.6 20.0 15.5 2.5 17.1 49.8 15.6 2.5 115 22-Feb-07 245.0 2.5 32.3 0.0 27.6 7.1 44.5 0.3 0.1 13.1 2.9557 0.4 0.1 16.6 12.6 20.0 14.9 2.5 17.1 50.1 15 2.6 116 23-Feb-07 1.9 28.0 0.0 0.3 0.1 16.8 0.2 0.1 19.7 12.6 20.0 2.6 16.6 50.1 2.4 117 24-Feb-07 12.4 34.7 0.1 33.3 7.0 0.6 0.1 15.3 0.1 18.3 12.6 20.7 15.1 2.6 16.6 51.1 15.2 2.5 118 25-Feb-07 408.5 248.1 3.3 3.6 40.4 34.2 0.1 7.1 75.0 0.4 0.4 0.3 2.6 15.5 50.1 0.0 0.4 0.5 0.0 19.9 18.9 23.2 0.1 13.9 1400.0 14.5 14.3 2.5 3020.0 246.0 7.7 444.0 15.7 5120.0 12.6 20.7 15.2 2.5 20.3 25.0 16.2 1090.0 17.0 18.0 1.5 2370.0 8.7 20.0 5070.0 16.6 51.1 15 2.5 119 26-Feb-07 7.3 12.6 21.0 2.5 16.1 52.8 2.5 120 27-Feb-07 323.6 267.9 3.6 32.6 0.0 0.6 0.1 15.4 0.3 0.0 17.4 12.6 20.7 14.8 15.6 52.2 14.8 121 28-Feb-07 3.5 34.8 0.1 27.0 1.2 0.4 14.6 0.3 0.0 17.7 12.6 20.7 15.3 15.1 122 1-Mar-07 7.2 12.6 123 2-Mar-07 383.4 7.0 12.6 23.7 14.0 2.5 15.6 52.2 14.2 2.5 124 3-Mar-07 7.1 12.6 23.7 13.9 2.3 15.6 50.8 13.9 2.4 125 4-Mar-07 484.0 2.5 30.9 0.0 28.9 7.1 0.5 0.0 14.4 0.2 0.0 17.7 12.6 24.7 2.5 15.6 55.9 2.3 126 5-Mar-07 336.2 238.7 3.5 2.4 37.6 33.2 0.0 44.5 7.3 39.0 0.2 0.5 0.4 0.1 13.3 25.1 0.0 0.2 0.4 0.0 19.6 17.2 21.7 0.2 8.7 960.0 6.2 10.4 2.4 3430.0 0.4 0.1 13.0 5160.0 12.6 24.7 15.6 2.3 13.0 26.0 0.1 10.6 1740.0 5.6 17.7 1.2 2260.0 0.4 0.3 19.6 4940.0 15.1 59.3 15.5 2.7 127 6-Mar-07 7.0 12.6 26.8 15.7 2.5 17.6 24.0 15.5 128 7-Mar-07 3.6 31.9 0.1 23.1 7.1 0.5 0.1 12.0 0.2 0.0 14.2 12.6 23.4 16.0 2.5 17.1 35.9 16.3 2.5 129 8-Mar-07 7.2 12.6 24.0 2.5 17.1 44.7 2.4 130 9-Mar-07 402.2 326.7 3.6 3.2 37.8 0.1 39.2 7.0 50.1 0.6 0.7 0.5 15.7 50.1 0.0 0.2 0.2 18.0 15.9 22.9 0.2 1470.0 8.7 12.2 2.1 1.0 0.2 15.6 4720.0 12.6 23.0 14.3 12.0 27.9 0.2 14.8 940.0 8.6 18.5 0.4 2210.0 26.6 0.5 462.0 0.1 17.4 5320.0 16.6 52.2 131 10-Mar-07 7.2 12.6 23.7 2.5 16.4 50.8 2.6 132 11-Mar-07 251.2 2.4 0.1 20.1 6.9 1.6 14.5 0.3 16.0 12.6 23.7 15.2 2.6 15.6 53.8 15.3 2.7 133 12-Mar-07 448.2 2.3 0.0 29.6 7.2 0.6 11.6 1.1 10.5 12.6 23.4 2.4 15.4 54.5 2.6 134 13-Mar-07 311.0 310.2 2.3 0.1 24.7 7.1 38.5 1.1 13.6 42.1 1.3 11.6 12.6 22.7 15.1 2.8 15.4 55.2 15 2.8 135 14-Mar-07 12.1 20.3 15.1 15.2 136 15-Mar-07 395.9 2.7 0.2 7.0 0.3 13.7 0.3 15.2 12.1 19.6 14.7 2.6 17.1 16.3 14.8 2.5 137 16-Mar-07 289.0 222.9 4.1 2.6 27.5 23.8 0.1 12.5 7.1 39.8 0.2 0.3 0.8 0.1 13.3 44.5 0.4 0.5 1.1 0.2 15.0 12.9 16.5 0.2 1490.0 5.1 8.4 3.4 3070.0 0.4 12.4 4600.0 12.1 19.6 14.1 2.5 10.8 20.1 0.3 13.8 1080.0 6.4 13.8 0.9 1360.0 0.6 0.2 14.5 5050.0 17.4 16.3 14.1 2.5 138 17-Mar-07 317.3 2.5 23.6 0.1 10.4 0.3 0.1 12.5 0.3 0.1 15.0 12.1 21.3 14.2 2.5 17.4 20.3 14.3 2.7 139 18-Mar-07 336.2 7.0 12.1 22.0 17.4 19.3 140 19-Mar-07 3.2 27.0 0.1 15.5 7.0 0.3 0.3 14.7 2.4 0.1 17.6 12.1 22.0 15.2 2.5 17.4 18.3 15.2 2.5 141 20-Mar-07 3.8 27.0 0.0 34.4 7.3 0.3 0.1 13.1 1.8 15.8 12.1 23.0 15.3 2.5 17.6 18.3 15.6 2.3 142 21-Mar-07 487.2 3.8 4.3 39.8 28.9 0.1 25.1 7.3 0.3 1.5 0.1 0.6 15.7 0.1 0.3 0.9 1.8 18.5 13.9 19.2 0.1 5.0 10.2 3.7 0.4 0.3 13.9 12.1 22.4 15.1 2.7 9.2 27.5 0.2 7.2 17.1 1.0 0.7 1.2 16.8 17.6 19.6 15.1 2.6 143 22-Mar-07 276.4 169.5 41.8 7.3 44.2 52.8 5.9 1510.0 3120.0 4600.0 12.1 21.0 14.7 2.7 25.3 940.0 2050.0 4960.0 17.6 20.7 14.7 2.3 144 23-Mar-07 355.0 1.3 30.1 0.0 28.4 7.0 0.6 0.4 15.4 0.3 0.2 18.7 12.1 21.3 14.9 2.5 17.6 20.3 15 2.7 145 24-Mar-07 238.7 3.2 28.3 0.1 7.2 0.2 0.3 11.5 0.3 0.1 13.9 12.1 21.7 2.5 17.6 20.3 2.8 146 25-Mar-07 2.5 22.4 0.2 7.0 0.4 0.5 12.6 0.7 0.7 15.3 12.6 21.7 14.8 2.5 19.6 15 2.5 147 26-Mar-07 320.1 198.7 5.5 3.7 38.3 31.6 0.1 17.6 7.1 5.7 0.2 0.3 1.1 1.0 13.8 22.4 0.1 0.8 1.0 0.1 18.4 14.7 19.3 0.1 6.6 1440.0 7.1 13.7 3.6 3300.0 0.5 0.5 12.8 4530.0 12.6 24.7 15.2 2.4 12.3 22.7 0.2 13.6 1170.0 6.7 15.1 1.5 2320.0 0.5 0.6 16.9 4900.0 17.6 19.3 15.2 2.5 148 27-Mar-07 1.1 30.9 0.1 17.1 1.0 0.2 13.2 0.3 0.2 18.0 12.6 24.4 15.4 2.5 17.6 19.6 15.4 2.5 149 28-Mar-07 387.2 7.3 12.6 23.0 17.6 19.3 150 29-Mar-07 3.3 30.0 0.1 17.6 15.1 0.6 3.6 15.6 0.3 1.3 20.6 24.0 15.4 2.6 17.6 19.6 15.3 2.5 151 30-Mar-07 390.8 210.6 4.3 3.9 37.2 36.4 0.1 17.0 15.7 7.2 36.2 0.2 0.3 0.9 15.8 30.7 0.2 0.3 1.0 1.2 18.2 21.6 0.2 1670.0 11.8 4.6 0.3 0.9 14.4 4490.0 16.1 2.7 11.2 35.3 0.2 16.3 860.0 8.2 17.9 0.3 2080.0 0.5 0.5 15.7 5040.0 17.6 19.0 16.4 2.3 152 31-Mar-07 153 1-Apr-07 2.6 29.4 0.1 21.2 15.4 7.2 0.9 12.7 0.4 15.3 15.7 2.5 15.8 2.7 154 2-Apr-07 410.5 2.8 36.1 0.2 34.9 15.3 7.0 0.3 1.8 12.4 0.4 14.9 12.6 23.4 15.9 2.5 17.6 18.3 15.8 3.1 155 3-Apr-07 440.6 2.8 15.0 6.9 0.3 0.3 0.0 15.5 15.2 156 4-Apr-07 26.6 0.3 15.2 7.2 0.1 11.8 0.0 13.6 12.6 23.4 15.6 2.6 17.6 18.6 15.3 2.4 157 5-Apr-07 158 6-Apr-07 290.4 190.5 3.4 3.6 34.6 27.1 0.1 21.6 16.0 7.2 25.1 0.1 0.3 1.3 0.1 10.9 75.0 0.3 0.3 1.0 0.1 13.8 15.8 17.0 0.3 9.0 1670.0 6.0 8.5 2.4 3270.0 0.4 0.3 11.2 4830.0 12.6 26.4 16.5 2.5 9.9 22.0 0.2 12.2 820.0 6.3 14.7 0.4 2250.0 0.5 0.2 14.2 5240.0 17.6 17.6 16.4 2.4 159 7-Apr-07 2.4 24.2 0.1 31.6 16.0 7.0 0.2 0.1 11.3 0.4 0.1 13.6 16.3 2.5 16.1 2.5 160 8-Apr-07 15.7 6.9 16.1 2.4 16.1 2.4 161 9-Apr-07 510.1 3.1 27.7 0.1 34.6 7.2 0.3 0.1 11.1 0.3 0.1 13.3 12.6 26.4 2.7 17.6 19.0 2.5 162 10-Apr-07 390.3 15.9 7.3 12.6 25.7 16.3 2.5 17.6 18.3 16.4 2.6 163 11-Apr-07 164 12-Apr-07 2.7 26.8 0.1 21.7 16.0 7.0 0.3 0.1 10.9 0.5 0.2 14.7 16.3 2.4 16.1 2.4 165 13-Apr-07 440.7 329.5 4.7 2.8 39.4 26.6 0.0 59.0 7.2 39.0 0.1 0.3 1.1 0.1 11.1 25.1 0.2 0.3 1.1 0.2 14.3 17.9 17.3 0.1 1750.0 4.0 8.1 2.5 4030.0 0.4 0.2 11.3 4580.0 12.6 26.8 11.7 22.3 0.1 900.0 8.6 15.3 0.2 2200.0 0.4 0.2 14.0 5010.0 17.6 17.3 166 14-Apr-07 7.1 167 15-Apr-07 16.0 7.0 12.6 26.4 16.2 2.5 17.6 16.9 16.3 2.4 168 16-Apr-07 382.2 356.4 5.1 3.6 32.4 33.0 0.1 28.2 7.1 88.7 0.1 0.4 1.1 0.1 14.3 22.335 0.2 0.7 0.5 0.0 14.4 16.2 17.8 0.1 10.2 2180.0 3.9 8.8 3.3 3620.0 0.4 0.2 14.4 4960.0 16.6 2.8 14.6 20.5 0.1 16.8 1580.0 6.1 13.4 0.3 2770.0 0.4 0.1 12.2 5290.0 16.8 2.6 169 17-Apr-07 385.5 18.2 7.2 12.6 27.1 2.7 17.6 17.9 2.5 170 18-Apr-07 391.9 2.2 43.1 0.0 45.9 16.7 7.2 0.0 0.1 13.1 0.3 0.1 15.2 16.9 2.6 16.8 2.7 171 19-Apr-07 456.4 266.1 16.5 7.0 19.4 19.449 12.6 27.1 16.9 2.5 17.6 17.9 16.7 2.5 172 20-Apr-07 6.5 55.8 0.0 6.9 0.3 0.1 15.4 0.4 0.0 22.2 2.5 2.7 173 21-Apr-07 16.4 7.2 12.6 27.4 16.8 2.5 17.6 17.3 16.9 2.7 174 22-Apr-07 378.5 278.3 3.8 3.9 35.7 33.6 0.0 43.6 16.3 7.3 29.5 0.2 0.4 0.6 0.0 17.6 33.9 0.1 0.5 0.3 0.0 18.2 21.9 0.1 10.6 11.1 3.6 0.2 14.5 12.6 27.8 16.7 2.5 27.8 0.1 18.1 19.4 0.4 0.0 17.9 17.6 16.9 2.5 175 23-Apr-07 7.0 12.6 27.8 2.5 17.6 17.9 2.6 176 24-Apr-07 177 25-Apr-07 7.1 2.5 2.5 178 26-Apr-07 16.1 16.7 16.8 179 27-Apr-07 16.2 16.9 16.7 180 28-Apr-07 16.5 16.8 16.6 181 29-Apr-07 182 30-Apr-07 183 1-May-07 12.6 28.1 17.6 17.6 184 2-May-07 433.8 253.2 5.7 39.6 0.0 15.4 7.1 36.8 0.3 0.0 12.1 22.335 1.1 0.0 17.3 1680.0 4080.0 4770.0 12.6 28.8 16.8 2.5 1100.0 2280.0 5110.0 17.6 16.9 16.8 2.6 185 3-May-07 278.6 259.7 33.4 7.0 36.8 22.335 18.4 12.4 28.1 2.5 14.8 17.6 17.6 2.5 186 4-May-07 7.2 12.1 3.1 17.6 3.0 187 5-May-07 44.2 6.9 9.1 2.9 11.3 2.7 188 6-May-07 16.4 16.9 3.2 17 3.3 189 7-May-07 3.7 28.8 0.0 7.2 0.3 0.1 12.2 0.4 0.0 15.1 12.1 30.1 2.4 17.6 17.9 3.1 190 8-May-07 369.3 246.8 56.4 16.9 7.3 39.6 42.535 11.3 1010.0 2130.0 2640.0 12.1 30.1 17.9 2.6 13.2 620.0 1350.0 2910.0 17.6 21.0 17.8 2.5 191 9-May-07 7.1 12.6 30.5 17.6 20.7 192 10-May-07 5.3 3.9 46.4 28.2 0.0 16.6 0.2 0.3 1.0 0.0 12.2 0.2 0.4 1.2 0.0 12.1 11.3 22.6 0.1 4.6 10.3 2.6 0.3 0.2 11.9 17.1 4.0 9.5 26.5 0.1 6.9 18.9 0.4 0.4 0.3 15.2 17 4.5 193 11-May-07 327.4 288.7 23.1 16.7 7.1 25.2 45.421 12.6 31.2 17.1 4.1 9.0 17.6 19.6 17 5.0 194 12-May-07 385.4 272.6 4.4 30.5 0.1 7.2 57.0 0.3 0.0 11.5 42.535 0.3 0.3 10.8 12.4 31.8 16.9 2.9 17.6 21.7 16.9 2.8 195 13-May-07 16.9 7.1 12.4 32.5 17.3 2.6 17.6 23.0 17.4 2.5 196 14-May-07 17.5 7.2 1020.0 1830.0 2560.0 17.7 2.5 690.0 1370.0 2730.0 17.5 2.6 197 15-May-07 446.7 214.5 4.6 6.1 37.9 48.9 0.0 23.6 17.4 0.1 1.3 1.1 0.1 16.0 0.2 0.3 1.4 0.5 16.2 12.4 23.8 0.2 8.2 3.3 11.9 2.3 0.4 0.2 13.5 12.4 33.2 17.7 2.5 8.5 29.4 0.1 7.9 20.0 0.3 0.4 0.6 16.9 17.6 22.4 17.8 2.5 198 16-May-07 401.6 3.6 55.3 0.1 7.2 0.6 0.1 22.2 0.3 0.0 18.0 2.5 2.5 199 17-May-07 369.3 240.3 4.8 55.9 0.1 17.6 7.1 51.2 0.4 0.0 17.4 54.078 0.3 0.0 18.0 930.0 1900.0 2740.0 11.8 36.2 18.0 2.8 460.0 1150.0 2820.0 17.6 23.4 18 2.4 200 18-May-07 17.9 7.0 12.4 18.2 18.2 201 19-May-07 4.5 38.2 0.0 27.8 17.8 0.3 0.1 11.3 0.3 0.1 14.8 10.3 12.4 18.1 2.4 16.8 18.3 2.5 202 20-May-07 443.5 7.1 12.4 40.0 2.5 17.6 23.7 2.4 203 21-May-07 472.5 4.8 38.2 0.0 7.2 0.3 0.0 11.2 0.5 0.1 16.2 2.5 2.5 204 22-May-07 26.6 16.8 7.0 3030.0 17.2 2.5 3450.0 17.2 2.5 205 23-May-07 385.5 237.1 5.2 2.9 41.9 35.0 0.0 17.0 7.1 44.2 0.2 0.3 1.2 0.0 11.0 43.9 0.2 0.5 1.1 0.0 14.2 12.4 27.4 0.1 1050.0 2.5 1.4 1.2 2570.0 0.4 0.0 20.5 2600.0 12.4 38.3 17.8 2.5 9.2 8.0 0.1 730.0 1.4 2.5 0.3 1610.0 0.5 0.0 19.2 3760.0 17.6 24.0 17.7 2.8 206 24-May-07 19.3 18.4 2.5 18.2 2.5 207 25-May-07 4.0 35.9 0.0 25.3 19.7 7.3 48.3 0.3 0.0 11.8 54.078 0.3 0.1 15.8 11.3 1190.0 2100.0 3510.0 12.4 40.6 19.0 14.2 600.0 1490.0 3370.0 17.6 24.7 18.9 2.5 208 26-May-07 379.0 304.8 7.1 2.8 2.7 209 27-May-07 5.7 4.0 40.6 37.5 0.1 51.2 0.2 0.5 1.0 0.0 11.8 48.306 0.2 0.3 0.9 0.0 15.8 13.1 22.4 0.0 2.4 10.0 2.4 0.1 0.1 11.4 12.6 42.0 2.7 7.4 28.1 0.2 4.4 18.7 0.8 0.3 0.2 13.9 17.6 23.4 2.5 210 28-May-07 330.4 231.7 22.0 18.5 7.1 39.1 38.6 1120.0 2350.0 3030.0 12.6 43.3 18.5 2.6 890.0 1600.0 3480.0 17.6 24.0 18.4 2.5 211 29-May-07 3.7 48.2 0.1 18.3 7.2 0.4 0.0 14.2 0.4 0.0 16.9 3120.0 18.2 2.5 3380.0 18.1 2.7 212 30-May-07 7.1 12.1 49.1 2.5 17.6 25.7 2.5 213 31-May-07 358.7 290.1 6.7 3.9 45.3 31.6 0.1 35.2 7.2 29.8 0.1 0.4 1.2 0.0 17.7 44.1 0.2 0.4 0.6 0.0 17.2 13.2 23.8 0.1 9.9 1150.0 2.5 13.9 1.6 2210.0 0.5 0.4 13.9 3170.0 2.5 10.7 32.0 0.1 16.3 770.0 5.1 22.2 0.7 1560.0 0.5 0.2 14.6 3170.0 2.7 214 1-Jun-07 215 2-Jun-07 397.4 254.3 4.1 37.9 0.1 54.1 0.4 0.0 13.5 56.963 0.4 0.1 15.1 12.1 51.5 17.6 25.1 216 3-Jun-07 1070.0 2420.0 2970.0 810.0 1630.0 3370.0 217 4-Jun-07 12.1 52.2 17.6 26.1 218 5-Jun-07 12.1 53.2 17.6 MEBPR (side-V) EFFLUENT EFFLUENT ANAEROBIC ANOXIC AEROBIC ANAEROBIC ANOXIC AEROBICINFLUENT MEBPR (side-C) MEBPR (side-V) MEBPR (side-C) 219 6-Jun-07 1190.0 2310.0 3260.0 870.0 1590.0 3410.0 220 7-Jun-07 in side-C in side-V in side-C in side-C in side-V in side-C in side-C in side-V Filtration operation hours FE SRT20a FE SRT20b FE SRT10a FE SRT20a FE SRT20b FE SRT10a FE SRT20b FE SRT10a kPa kPa kPa kPa kPa kPa kPa kPa 0 12.4 12.3 12.3 10.9 10.4 11.4 12.6 12.8 0.5 13.0 12.5 12.6 11.3 10.4 11.6 12.7 12.6 1 13.3 12.9 12.7 11.8 10.5 11.7 12.5 12.8 1.5 13.5 12.9 12.9 12.0 10.5 12.7 12.5 13.0 2 13.5 12.9 12.8 12.1 10.5 12.8 12.6 13.2 2.5 13.7 13.3 13.3 12.1 10.7 13.4 13.1 13.4 3 13.8 13.3 13.6 12.3 10.6 13.4 12.8 13.6 3.5 13.9 13.4 13.9 12.2 10.6 13.2 12.6 13.9 4 14.0 13.5 14.3 12.3 10.9 14.0 12.8 14.1 4.5 13.8 13.5 14.7 12.4 10.8 14.0 12.9 14.4 5 14.0 13.6 14.9 12.4 10.8 14.0 12.7 14.5 5.5 14.3 13.8 15.2 12.6 10.9 13.9 12.8 14.7 6 14.4 14.0 15.7 12.7 11.1 14.6 12.7 14.9 6.5 14.3 14.0 15.9 12.7 11.0 15.3 12.6 15.1 7 14.6 14.0 15.8 12.6 10.9 14.6 13.0 15.4 7.5 14.6 14.1 16.4 12.6 11.0 14.6 13.0 15.6 8 14.7 14.2 16.4 12.7 11.1 15.2 13.5 16.0 8.5 14.5 14.3 17.0 12.5 11.1 14.9 13.3 16.0 9 14.4 14.1 17.3 12.4 11.1 15.6 13.0 16.1 9.5 14.9 14.3 17.7 12.7 11.0 15.8 13.4 16.4 10 14.8 14.3 18.0 12.7 11.0 16.0 13.3 16.5 10.5 14.7 14.3 17.9 12.7 11.1 16.8 13.1 16.7 11 15.0 14.2 18.1 12.6 11.1 16.3 13.1 16.9 11.5 14.3 14.2 18.2 12.7 11.0 17.0 13.3 16.9 12 14.4 14.2 18.8 12.8 10.9 15.9 13.1 17.2 12.5 14.9 14.3 18.6 13.0 10.9 16.2 13.3 17.4 13 15.1 14.4 18.8 13.0 11.0 16.0 13.3 17.5 13.5 15.1 14.5 19.0 13.0 11.1 16.3 13.1 17.5 14 14.7 14.7 19.2 12.7 11.0 16.4 13.4 17.6 14.5 14.2 15.0 18.9 12.8 11.3 16.2 13.7 17.8 15 14.9 14.9 19.4 12.9 11.2 16.4 13.3 18.0 15.5 14.5 15.2 19.5 13.0 11.3 16.1 13.8 18.1 16 15.2 15.2 19.6 13.2 11.4 19.8 13.6 18.3 16.5 15.2 15.1 19.9 13.1 11.3 20.1 13.4 18.4 17 15.3 15.3 20.1 12.9 11.4 20.3 13.6 18.4 17.5 15.3 15.4 20.2 13.0 11.5 21.1 13.5 18.9 18 15.4 15.5 19.7 13.1 11.5 20.8 13.6 18.5 18.5 15.5 15.6 20.0 13.1 11.5 20.4 13.5 18.7 19 15.5 15.6 20.1 13.2 11.6 21.3 13.6 19.0 19.5 15.6 15.7 20.2 13.0 11.7 21.5 13.4 19.2 20 15.6 15.7 19.7 13.1 11.6 22.3 13.6 19.2 20.5 15.9 15.8 19.8 13.2 11.6 22.2 13.5 19.6 21 15.9 15.7 20.2 13.1 11.5 22.4 13.7 19.6 21.5 15.8 15.8 20.1 13.0 11.6 22.5 13.5 19.8 22 15.8 15.7 20.1 12.9 11.5 23.4 13.3 20.0 22.5 15.9 15.8 20.2 12.9 11.4 22.5 13.4 20.1 23 15.7 15.8 20.6 13.1 11.5 22.9 13.5 20.2 23.5 15.8 15.9 20.9 13.1 11.6 23.6 13.4 20.3 24 16.1 16.2 21.0 13.3 11.6 23.0 13.8 20.4 24.5 15.9 15.9 21.3 13.3 11.0 23.9 13.6 20.6 25 15.9 16.0 21.1 13.4 11.1 23.7 13.6 20.6 25.5 15.9 15.9 21.1 13.4 11.0 24.0 13.7 20.8 26 16.2 16.0 21.9 13.5 11.0 24.0 13.8 21.0 26.5 16.1 16.1 22.1 13.5 11.0 24.5 13.6 21.1 27 16.2 16.1 22.3 13.4 11.0 24.9 13.7 21.2 27.5 16.2 16.2 22.6 13.3 11.0 25.2 13.7 21.4 28 16.2 16.2 22.5 13.7 11.0 25.1 13.6 21.4 28.5 16.2 16.1 22.4 13.6 11.0 25.7 13.4 21.7 29 16.4 16.1 23.3 13.6 11.0 25.3 13.7 21.9 29.5 16.2 16.0 23.2 13.8 11.0 26.4 13.6 21.9 30 16.4 16.3 23.7 13.7 11.1 26.1 13.7 22.1 30.5 16.4 16.4 23.6 13.8 11.2 26.4 13.6 22.3 31 16.5 16.3 24.2 13.8 11.0 26.8 13.8 22.3 31.5 16.5 16.5 24.4 13.8 11.3 26.7 13.8 22.7 32 16.4 16.4 24.6 14.0 11.1 26.3 13.7 22.8 32.5 16.6 16.5 25.0 14.1 11.2 27.2 13.8 23.0 33 16.9 16.5 25.0 14.1 11.2 27.5 13.7 23.0 33.5 16.9 16.7 24.6 14.0 11.4 27.5 13.7 23.2 34 16.5 16.6 25.5 13.9 11.0 27.9 13.7 23.3 34.5 17.0 16.7 25.3 14.0 11.3 28.8 13.9 23.4 35 16.8 15.5 26.0 14.0 11.2 28.8 13.4 23.5 35.5 17.2 16.2 26.2 13.9 11.2 29.1 13.9 23.7 36 17.0 15.8 26.6 13.9 11.0 29.1 13.7 23.8 36.5 17.0 0.0 25.9 14.1 11.1 28.8 13.8 24.0 37 17.1 11.5 25.7 14.1 11.2 28.8 14.1 24.1 37.5 17.3 11.0 25.5 14.1 11.2 29.5 13.8 24.1 38 17.2 11.8 27.4 14.2 11.2 29.5 14.0 24.3 38.5 17.3 11.2 27.6 14.1 11.3 29.7 13.9 24.4 39 17.2 13.8 27.8 14.2 12.1 29.4 13.7 24.7 39.5 17.0 14.6 27.9 14.0 12.2 30.0 13.7 24.8 40 17.1 17.1 28.0 13.9 14.2 30.5 14.1 25.0 40.5 16.9 16.8 27.6 13.9 14.1 30.2 13.9 25.1 41 16.8 17.2 28.2 14.0 14.1 31.1 14.0 25.2 41.5 17.0 17.0 27.5 14.0 14.0 31.1 13.9 25.5 42 16.9 17.1 27.3 14.1 14.0 31.3 14.0 25.7 42.5 17.2 17.6 27.6 14.0 14.1 31.1 13.7 25.9 43 17.6 17.5 28.4 14.2 14.1 30.8 13.7 26.2 43.5 17.6 17.1 29.1 14.0 14.2 31.6 13.8 26.5 44 17.5 16.9 28.2 14.0 14.2 32.3 14.0 26.8 44.5 17.6 17.7 27.9 14.0 14.2 32.0 13.9 26.9 45 17.6 17.4 28.8 14.1 14.1 32.1 13.8 27.2 45.5 17.5 17.6 29.4 13.9 14.4 31.9 14.1 27.4 46 17.4 18.3 29.8 14.2 14.3 32.4 14.1 27.8 46.5 17.7 18.2 29.9 14.0 14.3 32.2 14.1 27.9 47 17.7 17.9 28.8 14.3 14.3 32.1 14.0 27.8 47.5 17.8 18.5 30.1 14.3 14.4 32.6 14.2 28.0 48 17.8 18.5 30.7 14.2 14.5 32.6 14.1 28.1 48.5 17.8 17.8 30.6 14.2 14.5 32.7 14.1 28.3 49 17.9 18.3 29.5 14.3 14.3 33.3 13.8 28.3 49.5 17.9 18.6 30.6 14.2 14.5 33.9 14.4 28.7 50 18.0 18.1 31.3 14.5 14.4 32.9 14.3 28.9 50.5 18.3 18.3 32.1 14.3 14.6 32.6 14.8 29.2 51 18.0 18.1 32.3 14.3 14.5 33.9 14.1 29.3 51.5 18.3 18.2 32.4 14.3 14.5 34.4 14.6 29.6 52 18.1 18.9 31.6 14.4 14.7 34.1 14.2 29.9 52.5 17.9 17.9 32.4 14.4 14.6 33.6 14.4 30.1 53 18.4 18.5 32.9 14.6 14.6 34.5 13.9 30.4 53.5 18.5 19.0 31.0 14.5 14.7 34.3 14.1 30.6 54 18.6 18.5 31.8 14.5 14.5 35.0 14.2 30.8 54.5 18.5 18.8 33.3 14.4 14.5 34.9 14.3 31.0 55 18.5 18.4 33.5 14.6 14.4 34.6 14.7 31.0 55.5 18.4 18.8 32.4 14.6 14.6 34.9 14.6 31.5 56 18.7 18.5 33.4 14.7 14.6 34.9 14.3 31.8 56.5 18.5 19.0 33.3 14.6 14.7 35.0 14.3 32.0 57 18.7 19.0 33.3 14.8 14.7 35.9 14.3 32.2 57.5 18.7 18.6 33.7 14.7 14.8 35.2 13.9 32.4 58 18.9 18.9 34.7 14.7 14.7 35.0 14.6 32.5 58.5 18.9 18.7 34.8 14.6 14.7 34.9 14.8 32.7 59 18.9 19.2 35.3 14.7 14.8 35.6 14.7 32.9 59.5 19.0 20.9 34.1 14.7 15.0 35.5 14.6 33.2 60 18.9 35.2 14.7 14.9 36.3 14.9 33.3 60.5 18.9 35.6 14.7 14.9 35.3 14.9 33.6 61 18.6 35.8 14.7 15.0 37.0 14.9 33.8 61.5 19.1 35.5 14.7 15.0 35.9 14.8 34.0 62 18.9 35.7 14.8 15.0 37.3 15.0 34.3 62.5 19.2 35.6 14.7 15.0 37.5 15.1 34.7 63 19.3 37.2 14.6 15.1 36.7 14.6 35.0 63.5 19.5 37.2 14.7 15.1 37.3 14.6 35.2 64 19.1 36.1 14.8 15.0 36.9 15.1 35.7 64.5 19.4 37.5 14.7 15.0 37.9 14.6 36.1 65 19.5 37.5 14.8 15.0 38.1 14.8 36.1 65.5 19.4 39.3 14.6 14.8 38.4 14.5 37.1 66 19.3 35.3 14.9 14.9 37.2 14.7 37.2 66.5 19.1 37.1 15.1 15.0 37.4 14.6 37.5 67 19.1 39.7 14.5 14.9 37.7 14.7 38.2 67.5 19.4 40.0 15.0 15.0 39.8 14.7 38.1 68 19.8 41.7 15.4 15.0 39.2 14.9 39.0 68.5 19.7 42.1 14.9 15.1 38.9 15.0 39.5 69 19.8 41.7 15.2 15.0 39.8 14.7 39.6 69.5 19.5 43.0 15.2 15.0 39.2 14.5 40.2 70 19.5 42.6 15.2 15.0 39.5 14.5 39.9 70.5 20.0 41.8 15.5 15.1 40.0 14.6 40.7 71 19.7 41.7 15.1 15.0 39.3 14.5 40.6 71.5 19.7 42.2 15.1 14.9 39.9 14.5 41.1 72 19.1 42.6 15.1 15.1 39.8 14.7 41.4 72.5 19.9 42.4 15.2 15.0 40.2 15.1 41.3 73 20.1 41.7 15.2 15.2 40.0 15.2 41.8 73.5 20.0 42.9 15.3 15.2 41.4 15.1 41.9 74 19.7 43.7 15.4 15.2 40.9 14.9 42.2 74.5 19.9 43.8 15.3 15.2 40.6 14.9 42.1 75 20.0 44.2 15.4 15.1 41.1 14.7 42.7 75.5 20.0 45.1 15.3 15.2 40.8 15.3 43.1 76 19.4 44.5 15.4 15.3 40.7 14.8 43.3 76.5 20.0 45.2 15.4 15.1 41.1 15.0 43.5 77 19.7 45.8 15.2 15.2 44.8 14.7 43.8 77.5 20.0 45.6 15.0 15.0 44.3 15.0 43.9 78 19.8 46.3 15.5 15.0 44.7 15.0 44.5 78.5 19.6 46.1 15.3 15.1 45.6 15.1 44.6 79 19.9 47.0 15.4 15.2 45.1 14.9 44.9 TM #1 TM #2 TM #3 79.5 20.3 47.9 15.5 15.3 45.2 15.1 45.5 80 20.2 48.8 15.3 15.2 46.1 15.3 45.5 80.5 20.1 48.8 15.3 15.2 45.2 15.0 45.9 81 20.0 48.2 15.3 15.2 45.7 14.8 46.3 81.5 20.2 48.9 15.6 15.3 46.8 15.0 46.4 82 20.2 48.4 15.1 15.5 46.5 15.3 46.4 82.5 20.1 48.6 15.5 15.5 48.0 15.0 47.1 83 20.5 48.8 15.2 15.4 46.7 15.2 46.9 83.5 20.4 48.7 15.3 15.7 46.4 15.2 47.8 84 20.1 50.4 15.3 15.6 47.2 15.2 47.7 84.5 20.0 51.6 15.3 15.6 46.1 15.1 48.1 85 20.2 52.4 15.5 15.7 47.6 15.0 47.8 85.5 19.9 53.2 15.3 15.5 47.5 15.3 48.8 86 20.6 49.6 15.5 15.8 47.4 15.2 49.2 86.5 20.3 51.3 15.4 15.9 47.5 15.3 49.8 87 20.3 52.3 15.4 15.7 49.2 15.1 50.3 87.5 20.5 53.1 15.5 15.7 49.4 15.0 50.4 88 20.1 54.0 15.3 15.9 47.8 15.2 51.4 88.5 20.6 52.7 15.5 15.8 49.0 15.3 51.0 89 20.5 52.9 15.6 15.9 50.8 15.5 52.4 89.5 20.6 51.6 15.7 15.9 49.9 15.1 53.2 90 20.6 53.3 15.4 15.8 50.7 15.1 53.5 90.5 20.4 53.3 15.5 15.8 49.8 15.0 54.4 91 20.4 54.7 15.4 15.9 50.3 15.1 91.5 20.8 53.2 15.4 15.7 51.0 15.2 92 20.8 53.6 15.5 16.0 50.9 15.3 92.5 20.5 53.3 15.4 15.9 52.6 15.3 93 20.6 53.7 15.3 15.6 51.7 15.4 93.5 20.8 53.7 15.2 15.7 51.8 15.1 94 20.8 50.9 15.5 16.0 48.7 15.4 94.5 20.8 15.5 15.8 15.3 95 20.8 15.6 15.8 15.4 95.5 20.9 15.5 15.9 15.2 96 21.0 15.4 16.0 15.3 96.5 21.0 15.6 16.0 15.1 97 20.9 15.6 15.9 15.3 97.5 20.9 15.2 16.1 15.5 98 20.8 15.5 16.1 15.5 98.5 21.4 15.7 16.2 15.5 99 20.9 15.7 16.2 15.4 99.5 21.2 15.7 16.0 15.5 100 21.0 15.7 16.1 15.5 100.5 20.6 15.3 16.2 15.6 101 20.9 15.7 16.1 15.4 101.5 21.4 15.5 16.2 15.4 102 21.1 15.6 16.1 15.3 102.5 21.1 15.7 16.0 15.3 103 21.0 15.5 16.1 15.3 103.5 21.3 15.8 16.1 15.4 104 20.7 15.6 16.2 15.5 104.5 21.1 15.8 16.1 15.5 105 20.8 15.9 16.4 15.4 105.5 20.7 15.7 16.4 15.4 106 20.9 15.6 16.4 15.6 106.5 21.0 15.6 16.4 15.4 107 21.4 15.7 16.4 15.6 107.5 21.3 15.7 16.5 15.5 108 21.0 15.7 16.5 15.5 108.5 21.0 15.9 16.8 15.5 109 21.4 15.8 16.7 15.6 109.5 21.4 15.9 16.6 15.6 110 21.4 15.7 16.7 15.6 110.5 21.1 15.7 16.7 15.4 111 20.9 15.7 16.6 15.7 111.5 21.4 15.8 16.7 15.8 112 21.8 15.8 16.7 15.7 112.5 21.7 15.8 16.7 15.7 113 21.2 16.2 16.9 15.8 113.5 22.3 16.5 16.7 16.2 114 21.8 16.2 16.6 16.3 114.5 21.9 16.3 16.7 16.4 115 22.0 16.2 16.7 16.4 115.5 22.4 16.3 16.9 16.3 116 21.3 16.1 16.7 16.4 116.5 21.4 16.1 16.9 16.6 117 22.2 16.1 17.0 16.6 117.5 21.8 16.3 16.9 16.6 118 21.6 16.1 17.0 16.2 118.5 22.3 16.2 16.9 16.7 119 21.6 16.1 17.1 16.7 119.5 22.4 16.3 17.0 16.7 120 22.6 16.3 17.1 16.5 120.5 22.5 16.4 17.2 16.5 121 22.2 16.3 17.0 16.7 121.5 22.5 16.3 17.2 16.6 122 22.1 16.3 17.3 16.8 122.5 22.3 15.8 17.3 16.8 123 22.0 15.8 17.3 17.1 123.5 22.0 16.0 16.8 16.9 124 21.5 16.1 17.3 17.0 124.5 22.3 16.3 17.4 17.0 125 22.4 16.4 17.3 16.9 125.5 22.1 16.2 17.3 16.8 126 22.5 16.3 17.2 16.9 126.5 22.5 16.1 17.3 16.9 127 22.7 16.2 17.4 17.0 127.5 22.5 16.2 17.5 16.9 128 22.5 15.8 17.6 17.1 128.5 22.7 16.5 17.5 17.3 129 22.5 16.3 17.6 17.3 129.5 22.6 16.3 17.6 17.1 130 21.9 16.3 17.6 17.1 130.5 22.1 16.3 17.6 16.9 131 22.2 16.3 17.7 17.0 131.5 22.3 16.3 17.8 17.2 132 23.1 16.6 18.0 17.4 132.5 22.5 16.3 17.8 17.1 133 22.6 16.3 18.0 17.4 133.5 22.0 16.2 17.7 17.1 134 22.8 16.3 18.0 17.0 134.5 22.4 16.3 17.9 17.5 135 23.1 16.4 17.9 17.7 135.5 22.9 16.3 18.2 17.2 136 23.1 16.3 18.0 17.1 136.5 23.1 16.3 18.1 17.4 137 23.0 16.6 18.2 17.3 137.5 23.1 16.4 18.1 17.3 138 23.2 16.6 18.2 17.4 138.5 22.7 16.4 18.1 17.2 139 22.8 16.2 18.0 17.5 139.5 23.0 16.7 18.2 17.7 140 23.2 16.5 18.1 17.4 140.5 22.8 16.3 18.2 17.6 141 23.1 16.5 18.1 17.6 141.5 22.5 16.5 18.2 17.5 142 23.3 16.4 18.2 17.5 142.5 22.3 15.9 18.1 17.9 143 23.1 15.9 18.5 17.8 143.5 22.2 16.2 18.5 17.8 144 22.4 16.4 18.5 17.0 144.5 22.1 16.0 18.2 17.2 145 23.0 16.6 18.5 17.8 145.5 22.8 16.2 18.3 17.9 146 22.4 16.2 18.6 17.6 146.5 22.4 16.0 18.6 18.1 147 22.3 16.3 18.1 17.2 147.5 22.6 16.3 18.5 17.9 148 23.0 16.3 18.6 17.7 148.5 23.6 16.4 18.5 17.2 149 22.8 16.6 18.5 17.9 149.5 23.0 16.7 18.5 17.8 150 23.1 16.6 18.6 17.9 150.5 22.9 16.6 18.4 17.8 151 22.9 16.7 18.5 17.9 151.5 23.2 16.6 18.5 18.0 152 22.8 16.6 18.5 17.9 152.5 23.2 16.7 18.6 17.9 153 23.3 16.7 18.6 17.9 153.5 23.3 16.6 18.8 17.7 154 23.0 16.7 18.9 18.1 154.5 23.2 16.6 19.0 18.2 155 23.0 16.6 18.8 18.0 155.5 23.0 16.8 18.7 17.8 156 23.3 16.7 19.0 18.0 156.5 18.4 0.0 18.9 18.3 157 17.5 0.0 18.8 18.1 157.5 18.9 16.4 19.1 18.3 158 18.3 17.3 19.0 17.8 158.5 18.6 17.7 19.2 18.0 159 18.8 17.9 19.1 18.1 159.5 17.9 18.1 19.0 18.2 160 17.4 18.1 18.7 17.7 160.5 18.6 17.9 18.7 18.0 161 18.1 17.7 19.0 18.0 161.5 18.4 17.6 19.0 17.5 162 17.9 17.7 18.8 17.9 162.5 18.7 18.0 19.0 17.8 163 18.6 18.0 18.9 17.8 163.5 18.1 18.2 18.9 17.6 164 18.8 18.5 19.1 17.6 164.5 17.9 19.0 19.1 17.6 165 19.0 18.9 18.8 18.1 165.5 18.3 18.8 19.0 18.0 166 18.3 18.9 18.7 17.6 166.5 18.5 19.1 19.1 18.2 167 18.6 18.9 19.0 17.9 167.5 18.0 18.9 18.9 18.1 168 19.7 18.9 19.2 18.0 168.5 18.5 19.7 19.3 18.1 169 18.4 19.5 19.3 17.7 169.5 19.2 19.3 19.2 17.8 170 18.5 19.4 19.2 17.9 170.5 18.2 19.3 19.2 17.9 171 19.0 19.7 19.3 18.2 171.5 18.2 19.8 19.3 18.5 172 18.9 19.8 19.2 18.4 172.5 19.1 20.0 19.1 18.6 173 18.8 20.3 19.2 18.4 173.5 18.5 20.5 19.3 18.3 174 18.4 20.1 19.1 18.3 174.5 18.7 20.4 19.2 18.0 175 18.7 19.9 19.2 18.4 175.5 18.5 20.0 19.2 18.2 176 19.6 20.2 19.3 18.2 176.5 18.6 20.4 19.4 18.3 177 19.2 20.5 19.4 18.1 177.5 19.3 21.4 19.4 18.6 178 19.5 21.3 19.4 18.5 178.5 19.2 21.0 19.6 18.6 179 18.8 21.4 19.6 18.6 179.5 18.0 21.1 19.3 18.2 180 18.6 21.7 19.7 18.5 180.5 18.8 21.7 19.7 18.8 181 18.9 22.1 19.9 18.8 181.5 19.5 23.4 19.8 18.4 182 16.6 21.3 19.7 18.2 182.5 18.4 21.6 20.1 18.6 183 18.1 18.6 20.0 18.1 183.5 19.1 18.8 19.7 18.7 184 19.8 19.2 19.9 18.4 184.5 19.7 18.8 19.8 18.7 185 19.7 19.4 19.6 18.3 185.5 18.8 19.2 19.7 18.1 186 20.2 19.2 19.7 18.5 186.5 19.6 19.0 19.6 18.3 187 19.4 19.1 19.6 18.3 187.5 19.4 19.7 19.9 18.5 188 19.2 19.6 19.8 18.5 188.5 20.7 19.8 19.6 18.3 189 20.2 19.6 19.8 18.3 189.5 20.9 19.7 20.0 18.5 190 20.9 19.3 19.8 18.6 190.5 20.4 19.8 19.7 18.5 191 19.4 19.6 19.9 17.9 191.5 19.7 19.8 19.9 18.5 192 20.0 19.7 20.0 18.3 192.5 21.2 19.8 19.8 18.5 193 19.2 19.9 20.0 18.3 193.5 20.0 20.0 19.8 18.3 194 20.7 19.8 19.8 18.5 194.5 20.0 18.9 19.9 18.7 195 20.0 19.1 19.9 18.7 195.5 21.0 19.6 19.7 18.8 196 18.8 19.4 20.1 18.4 196.5 21.0 19.7 20.0 18.5 197 20.8 19.6 19.8 18.4 197.5 20.5 19.2 19.8 18.6 198 20.5 19.1 19.7 18.6 198.5 20.2 19.3 19.8 18.9 199 19.8 19.3 19.8 18.8 199.5 21.4 19.3 19.8 18.6 200 19.8 19.2 19.8 18.2 200.5 20.8 19.6 20.0 18.5 201 20.4 19.5 20.3 18.6 201.5 20.9 19.9 20.4 18.1 202 22.1 20.2 20.5 20.0 202.5 19.4 19.6 20.3 19.6 203 20.7 19.7 20.6 19.6 203.5 20.2 20.1 20.7 20.3 204 20.6 20.3 20.7 19.9 204.5 20.9 20.0 20.7 20.1 205 21.7 20.3 20.8 19.9 205.5 21.8 20.6 20.8 19.6 206 21.3 20.8 20.7 20.2 206.5 20.4 21.2 20.6 20.3 207 22.4 20.7 20.9 20.6 207.5 21.4 21.0 20.7 19.6 208 21.4 21.2 21.1 19.8 208.5 22.3 21.4 21.0 19.5 209 22.0 21.3 21.0 19.2 209.5 22.4 20.9 20.8 19.6 210 21.9 21.3 20.9 19.4 210.5 19.9 21.1 20.7 19.4 211 22.3 21.4 20.8 19.4 211.5 21.8 21.2 20.9 19.4 212 22.4 21.2 20.8 19.5 212.5 22.7 21.2 20.7 19.8 213 22.1 21.3 20.8 19.7 213.5 21.3 20.8 20.9 19.2 214 23.1 21.2 21.1 19.1 214.5 22.9 21.3 21.3 19.6 215 22.8 21.4 21.0 19.3 215.5 22.3 21.3 20.9 19.5 216 22.8 21.3 21.2 19.7 216.5 23.0 21.0 21.2 19.6 217 22.0 21.4 21.2 19.9 217.5 22.3 21.6 21.0 20.0 218 23.5 21.5 21.0 19.8 218.5 23.2 21.3 21.1 19.9 219 21.9 21.5 21.3 19.6 219.5 23.3 20.8 21.3 19.8 220 23.5 20.5 21.5 20.1 220.5 22.2 20.5 21.2 20.3 221 22.2 20.8 21.2 19.9 221.5 22.0 21.1 21.3 19.4 222 22.8 20.8 21.3 20.3 222.5 23.5 20.8 21.1 19.9 223 23.6 20.3 21.3 19.8 223.5 22.9 20.6 21.2 20.1 224 23.1 21.2 21.0 20.1 224.5 23.9 21.2 21.3 20.1 225 22.7 21.4 21.5 20.3 225.5 24.2 21.5 21.6 19.3 226 25.2 21.5 21.5 20.3 226.5 24.9 21.4 21.8 20.4 227 23.3 21.6 21.9 20.6 227.5 24.6 21.9 21.8 20.0 228 23.6 22.1 22.1 20.2 228.5 24.4 22.2 21.7 20.3 229 24.7 22.7 22.2 20.3 229.5 23.8 22.7 21.9 20.4 230 24.6 22.6 22.0 20.7 230.5 24.5 22.7 22.2 20.2 231 25.3 23.1 22.3 20.8 231.5 25.0 23.0 21.9 20.6 232 25.4 22.5 22.3 20.3 232.5 26.4 22.2 22.4 20.6 233 24.8 23.0 22.1 20.3 233.5 24.7 22.5 22.3 20.6 234 25.5 22.3 22.5 20.5 234.5 24.4 23.0 22.3 20.5 235 25.3 22.5 22.4 21.0 235.5 25.1 22.3 22.1 20.2 236 26.1 22.6 22.5 20.9 236.5 25.0 22.4 22.5 20.7 237 25.1 22.3 22.7 20.4 237.5 24.5 22.5 22.4 20.9 238 24.9 22.4 22.8 20.7 238.5 25.6 22.0 23.0 20.4 239 26.0 22.1 22.8 20.6 239.5 27.0 22.4 22.7 20.4 240 26.4 22.6 22.8 21.0 240.5 25.4 22.6 22.5 20.1 241 26.2 22.3 22.8 20.6 241.5 26.1 23.2 22.7 20.4 242 25.5 22.3 22.7 20.6 242.5 26.1 22.8 22.8 20.4 243 27.2 22.8 22.5 20.3 243.5 27.0 23.1 23.1 20.9 244 25.5 23.0 22.9 20.6 244.5 27.0 23.1 23.0 20.5 245 26.8 23.0 23.2 20.5 245.5 25.7 23.0 23.2 20.7 246 27.2 23.1 22.5 20.4 246.5 26.4 22.8 22.9 21.2 247 27.4 23.1 22.8 20.6 247.5 27.3 23.2 23.0 20.8 248 26.8 23.3 23.4 20.9 248.5 26.5 22.9 23.5 21.0 249 27.5 23.4 23.4 20.5 249.5 26.2 22.9 23.5 21.1 250 26.6 23.2 23.4 20.6 250.5 27.4 22.9 23.3 20.6 251 26.7 22.1 23.0 20.6 251.5 27.0 22.7 23.7 20.3 252 27.9 22.8 23.7 20.6 252.5 27.8 22.8 23.5 20.5 253 29.7 23.2 23.2 20.6 253.5 30.2 23.3 23.4 20.6 254 29.9 23.4 23.3 20.8 254.5 30.4 23.7 23.8 20.8 255 20.1 23.9 20.6 255.5 21.7 23.5 21.0 256 23.0 23.2 20.8 256.5 25.5 23.1 23.7 20.0 257 26.4 23.0 23.8 20.5 257.5 26.5 23.0 23.4 20.3 258 26.3 23.2 23.5 20.8 258.5 26.9 23.2 23.7 20.4 259 26.5 23.3 23.5 20.8 259.5 26.1 23.0 23.8 20.6 260 26.7 23.2 23.9 20.2 260.5 27.3 23.4 23.6 20.5 261 27.1 23.7 23.8 20.4 261.5 27.0 23.7 24.1 20.4 262 27.2 23.7 23.4 20.5 262.5 27.3 23.4 23.6 20.4 263 27.0 23.6 23.2 20.3 263.5 26.8 24.0 23.5 20.2 264 27.5 23.9 23.5 20.5 264.5 27.3 24.4 23.6 21.0 265 27.2 23.9 23.4 20.1 265.5 27.4 24.2 23.8 20.5 266 28.1 24.5 23.8 20.7 266.5 27.8 24.6 23.7 20.4 267 28.1 23.9 23.8 20.0 267.5 28.1 24.7 23.6 20.7 268 28.6 24.8 23.8 20.3 268.5 26.9 24.3 23.9 20.2 269 27.4 24.4 23.5 20.9 269.5 28.3 24.5 23.5 20.9 270 28.1 24.3 23.6 20.3 270.5 28.2 24.7 23.7 20.6 271 28.6 24.3 23.7 20.5 271.5 28.7 24.6 23.5 20.9 272 28.6 24.5 23.7 20.8 272.5 29.1 24.6 24.0 20.6 273 28.1 24.6 24.2 21.0 273.5 28.8 24.7 24.3 20.8 274 28.5 25.0 24.1 20.7 274.5 28.8 24.9 24.2 20.3 275 29.4 25.8 24.2 20.1 275.5 27.2 25.3 24.3 20.5 276 27.8 25.4 24.4 20.4 276.5 27.6 25.1 24.3 20.8 277 27.7 25.7 24.6 21.1 277.5 27.5 26.0 24.4 20.8 278 27.1 25.7 24.4 21.2 278.5 28.5 26.0 24.7 20.9 279 27.9 26.0 24.5 20.4 279.5 28.1 26.4 24.6 20.9 280 27.5 26.0 24.8 20.4 280.5 28.2 26.3 24.8 21.3 281 27.5 26.1 25.1 21.5 281.5 27.9 25.6 24.2 21.6 282 27.1 25.9 24.3 21.1 282.5 27.9 25.7 24.2 21.5 283 28.0 25.8 24.3 21.3 283.5 28.3 25.6 24.3 21.4 284 27.7 25.8 24.5 21.3 284.5 27.9 25.8 24.7 21.4 285 28.2 26.4 24.1 21.5 285.5 27.9 26.3 24.9 21.4 286 27.4 26.0 24.2 21.4 286.5 27.7 26.1 24.4 21.2 287 28.3 25.9 24.6 20.9 287.5 28.0 25.9 24.5 21.2 288 27.9 26.4 24.4 21.0 288.5 28.8 25.7 24.3 20.9 289 28.5 26.3 24.6 21.3 289.5 28.9 26.3 24.2 21.2 290 28.6 26.0 24.6 21.5 290.5 28.6 26.3 24.5 21.3 291 28.3 26.4 24.4 21.3 291.5 28.5 26.3 24.5 21.5 292 28.6 26.1 24.5 21.2 292.5 28.5 26.6 24.4 21.3 293 29.2 26.3 24.6 21.3 293.5 28.5 26.2 24.6 21.3 294 28.6 26.1 24.5 21.3 294.5 28.4 26.0 24.6 21.0 295 28.8 26.2 24.4 21.0 295.5 28.9 26.1 24.4 21.1 296 29.0 25.7 24.6 21.0 296.5 28.7 26.1 24.7 21.1 297 29.6 25.9 25.1 21.5 297.5 28.7 26.1 25.0 21.4 298 29.4 26.0 25.0 21.5 298.5 29.0 26.0 25.1 21.4 299 29.3 26.2 25.0 21.3 299.5 29.7 26.3 25.3 21.2 300 29.4 26.1 25.4 21.7 300.5 29.2 26.6 25.3 21.8 301 30.3 26.9 25.5 21.5 301.5 29.9 26.8 25.2 22.3 302 30.3 26.6 25.7 22.3 302.5 29.4 27.0 25.9 22.3 303 29.7 27.1 26.0 22.2 303.5 29.7 26.8 25.7 22.9 304 29.8 27.1 25.8 23.0 304.5 31.3 28.3 25.7 22.5 305 29.8 29.3 25.9 23.2 305.5 30.7 29.2 25.6 23.2 306 30.8 29.5 26.0 22.8 306.5 30.5 29.7 25.9 22.6 307 31.0 29.6 26.0 23.0 307.5 30.5 29.3 26.1 22.8 308 31.4 30.2 26.2 22.8 308.5 31.4 30.2 26.3 23.1 309 30.9 29.7 26.4 23.0 309.5 31.8 30.2 26.4 22.8 310 31.1 30.4 26.6 23.7 310.5 31.6 29.6 26.1 23.3 311 31.7 29.9 26.7 22.8 311.5 31.8 30.4 26.6 22.9 312 32.2 30.3 26.6 23.2 312.5 31.9 30.4 26.5 23.2 313 32.4 30.3 26.8 23.2 313.5 32.6 30.7 26.9 23.3 314 32.9 30.7 26.3 23.0 314.5 32.8 30.8 26.6 23.2 315 33.2 30.9 27.1 23.1 315.5 33.5 30.9 26.8 23.7 316 33.6 31.0 26.8 23.4 316.5 33.5 30.6 26.8 23.5 317 33.7 31.0 26.9 23.5 317.5 34.1 31.2 27.0 23.1 318 32.4 31.6 26.8 23.2 318.5 34.3 31.0 26.9 22.9 319 33.8 30.7 26.9 23.6 319.5 34.1 30.7 26.6 23.0 320 33.9 31.1 26.7 22.7 320.5 34.1 31.1 27.5 23.6 321 33.3 30.6 27.5 23.3 321.5 34.4 31.2 27.5 23.4 322 34.3 31.2 27.7 23.6 322.5 34.9 31.4 27.6 23.4 323 34.1 31.2 27.9 23.5 323.5 34.6 31.4 27.8 23.3 324 35.0 31.9 27.2 23.3 324.5 35.8 32.2 27.4 23.3 325 34.8 32.7 27.5 22.9 325.5 35.6 33.7 27.9 23.5 326 36.0 33.8 27.8 23.4 326.5 36.0 33.5 27.9 23.4 327 36.3 34.2 28.1 23.5 327.5 36.0 34.1 27.5 23.5 328 35.8 34.0 28.0 23.7 328.5 35.2 34.3 28.0 23.6 329 36.8 34.2 27.5 23.5 329.5 35.9 33.9 27.9 23.7 330 36.2 34.2 27.6 23.9 330.5 36.4 33.8 27.2 23.3 331 36.6 34.3 27.2 23.2 331.5 36.7 34.2 27.6 23.4 332 36.8 34.4 27.6 23.3 332.5 36.8 34.3 27.1 23.4 333 37.2 34.4 27.4 23.6 333.5 37.2 34.6 27.9 23.4 334 36.9 34.3 27.8 23.5 334.5 37.5 34.6 28.2 23.8 335 37.8 34.5 28.1 23.5 335.5 36.5 33.6 28.2 23.8 336 38.1 34.7 28.0 23.5 336.5 38.1 35.2 28.0 23.7 337 38.4 35.0 28.2 23.6 337.5 38.6 35.4 28.3 23.7 338 38.3 34.9 27.9 23.4 338.5 37.9 34.9 28.3 23.9 339 38.8 35.2 28.6 23.5 339.5 39.1 35.3 28.2 23.5 340 39.0 35.1 28.4 23.4 340.5 39.1 35.4 28.6 24.3 341 39.0 35.3 28.8 24.0 341.5 38.7 35.1 28.9 24.1 342 39.6 35.3 28.8 23.7 342.5 38.3 34.2 28.6 23.5 343 39.0 35.1 28.8 24.0 343.5 39.5 35.1 28.6 24.1 344 39.3 35.3 28.2 23.7 344.5 39.3 35.3 28.7 23.8 345 38.6 35.0 28.9 24.1 345.5 38.4 34.7 28.5 25.2 346 39.5 35.8 28.7 25.4 346.5 40.3 36.4 28.6 25.1 347 39.4 35.9 28.5 25.3 347.5 38.7 35.0 28.5 24.9 348 39.6 35.7 28.6 24.7 348.5 39.8 36.3 28.5 24.5 349 40.1 36.7 28.9 24.6 349.5 40.2 37.2 28.5 24.5 350 39.2 36.3 28.6 24.6 350.5 40.4 37.8 28.7 24.6 351 40.5 37.7 28.5 25.1 351.5 40.5 37.7 28.3 24.9 352 40.2 37.3 28.1 25.0 352.5 40.4 37.5 28.1 24.7 353 39.4 37.1 28.4 24.8 353.5 40.9 37.4 28.3 24.4 354 40.6 36.8 28.2 25.2 354.5 40.8 38.0 28.5 26.1 355 40.8 37.4 28.3 25.9 355.5 40.8 37.1 28.3 26.2 356 40.4 37.5 28.5 26.1 356.5 41.2 37.8 28.9 26.5 357 41.2 37.5 28.6 26.2 357.5 41.1 37.3 28.7 26.3 358 40.8 37.1 28.6 26.4 358.5 40.8 37.7 28.2 26.5 359 40.6 36.9 28.2 26.4 359.5 40.6 36.8 28.9 26.4 360 41.4 37.6 28.7 26.3 360.5 41.7 37.7 28.7 26.4 361 41.3 38.0 28.8 26.5 361.5 42.0 38.1 29.1 26.7 362 42.0 38.4 29.1 27.1 362.5 42.2 38.3 29.2 26.7 363 42.2 38.0 29.2 26.6 363.5 42.2 37.6 29.2 26.7 364 42.2 37.7 29.2 26.8 364.5 41.5 37.2 29.3 26.5 365 41.7 37.1 28.9 26.6 365.5 42.3 37.8 29.2 26.6 366 41.8 37.6 29.1 26.8 366.5 42.1 37.9 28.8 26.8 367 41.9 37.2 29.3 27.2 367.5 42.6 37.7 28.9 27.0 368 42.5 38.3 28.9 27.4 368.5 42.6 37.6 29.1 27.1 369 42.5 37.7 29.0 27.7 369.5 41.7 37.8 29.2 27.5 370 41.4 37.4 29.0 27.0 370.5 41.9 38.3 29.1 27.2 371 42.4 38.6 29.5 27.3 371.5 42.4 38.3 29.6 27.9 372 43.3 39.6 29.8 27.7 372.5 43.5 40.0 29.6 27.0 373 43.5 39.7 29.8 27.2 373.5 42.2 39.4 29.6 27.8 374 43.7 39.9 30.1 27.3 374.5 43.3 39.4 29.9 27.1 375 43.9 40.3 29.5 27.1 375.5 43.1 39.2 29.1 27.2 376 43.8 39.6 376.5 43.6 40.0 377 44.2 40.9 377.5 42.7 39.5 378 43.5 40.4 378.5 42.9 39.3 379 43.9 40.2 379.5 43.5 39.9 380 43.5 39.1 380.5 42.9 39.5 381 43.6 39.8 381.5 42.8 39.1 382 43.5 39.7 382.5 43.0 39.2 383 43.9 39.7 383.5 43.3 39.2 384 43.9 40.0 384.5 43.2 39.6 385 44.5 40.3 385.5 43.6 40.0 386 43.6 40.1 386.5 43.6 40.0 387 44.0 39.7 387.5 44.8 40.7 388 45.1 40.8 388.5 44.9 40.8 389 45.3 40.8 389.5 45.2 41.1 390 44.6 40.2 390.5 44.9 40.1 391 44.9 39.6 391.5 45.3 40.4 392 44.7 40.5 392.5 43.7 39.7 393 45.1 40.6 393.5 45.3 40.3 394 45.2 40.1 394.5 44.4 40.2 395 45.0 40.7 395.5 45.6 41.4 396 44.9 41.1 396.5 45.1 41.8 397 44.6 41.4 397.5 45.4 42.2 398 45.7 42.1 398.5 44.5 40.8 399 45.7 41.6 399.5 44.5 41.1 400 46.1 42.3 400.5 45.8 42.4 401 44.8 41.2 401.5 46.1 42.0 402 45.4 41.1 402.5 45.0 41.2 403 46.1 41.8 403.5 45.8 41.9 404 44.9 40.8 404.5 46.1 41.8 405 45.9 42.1 405.5 46.0 41.7 406 46.0 42.1 406.5 46.1 41.9 407 46.0 41.2 407.5 46.2 42.0 408 44.5 40.7 408.5 45.9 42.2 409 45.5 41.5 409.5 45.5 41.6 410 45.3 41.3 410.5 45.5 42.2 411 45.8 41.6 411.5 45.7 42.0 412 46.8 42.3 412.5 44.9 41.3 413 46.1 42.2 413.5 45.9 42.0 414 46.5 41.3 414.5 45.8 41.6 415 46.0 42.3 415.5 45.4 41.6 416 45.9 42.1 416.5 45.9 41.8 417 45.2 41.6 417.5 46.6 42.2 418 46.3 42.5 418.5 45.9 42.3 419 45.9 42.4 419.5 46.4 42.8 420 46.0 43.0 420.5 44.7 42.0 421 46.9 43.8 421.5 46.6 43.5 422 46.5 44.5 TTF TTF min min Operating day Date 134 13-Mar-07 7.6 6.9 6.8 32.7 33.9 34.3 4.7 4.5 5.3 11.8 10.9 11.8 9.7 12.4 13.2 0.9 0.8 0.9 5.9 7.2 5.7 20.6 26.5 24.7 3.6 5.2 4.1 15.2 14.4 28.1 30.5 27.7 1.9 1.8 1.8 135 14-Mar-07 136 15-Mar-07 137 16-Mar-07 138 17-Mar-07 139 18-Mar-07 140 19-Mar-07 141 20-Mar-07 10.5 11.8 11.0 30.8 30.8 29.3 1.6 2.0 1.8 17.6 16.4 17.0 3.1 3.8 3.8 1.0 0.8 1.0 9.0 9.0 8.8 21.3 20.0 20.7 0.9 1.4 1.0 19.8 19.3 20.6 4.2 4.6 5.3 1.8 1.7 1.8 142 21-Mar-07 143 22-Mar-07 55.6 53.1 48.2 31.3 41.2 40.9 37.7 24.8 144 23-Mar-07 145 24-Mar-07 146 25-Mar-07 147 26-Mar-07 148 27-Mar-07 46.4 42.3 43.3 27.2 9.8 10.0 8.6 31.4 30.4 1.6 1.5 18.8 19.8 17.2 5.9 5.9 5.5 33.4 34.3 33.9 17.0 6.6 6.8 7.7 23.2 27.0 24.1 1.6 1.7 1.3 12.5 13.9 13.1 6.4 8.6 5.1 6.4 6.6 7.0 149 28-Mar-07 150 29-Mar-07 151 30-Mar-07 24.7 17.2 152 31-Mar-07 153 1-Apr-07 154 2-Apr-07 155 3-Apr-07 156 4-Apr-07 52.8 48.8 48.6 24.8 28.7 34.6 31.6 19.0 157 5-Apr-07 158 6-Apr-07 35.7 32.7 38.0 22.2 35.2 33.2 35.5 18.3 159 7-Apr-07 160 8-Apr-07 161 9-Apr-07 162 10-Apr-07 163 11-Apr-07 164 12-Apr-07 36.6 41.9 34.4 19.8 36.2 37.2 35.7 19.8 165 13-Apr-07 166 14-Apr-07 167 15-Apr-07 168 16-Apr-07 35.5 36.8 34.0 20.5 36.8 35.0 35.8 21.4 169 17-Apr-07 170 18-Apr-07 171 19-Apr-07 172 20-Apr-07 173 21-Apr-07 174 22-Apr-07 34.2 35.7 35.2 21.2 31.6 31.5 32.1 19.5 175 23-Apr-07 176 24-Apr-07 177 25-Apr-07 178 26-Apr-07 179 27-Apr-07 180 28-Apr-07 181 29-Apr-07 182 30-Apr-07 183 1-May-07 24.0 18.9 184 2-May-07 42.7 40.6 36.7 33.4 28.6 29.2 185 3-May-07 186 4-May-07 187 5-May-07 188 6-May-07 189 7-May-07 31.8 33.3 32.7 32.6 32.8 33.0 190 8-May-07 8.6 8.4 10.3 9.5 9.5 12.3 38.5 49.4 50.1 23.9 20.9 21.4 2.3 2.3 1.8 191 9-May-07 192 10-May-07 193 11-May-07 27.2 29.7 25.7 13.7 23.6 22.6 23.2 10.3 194 12-May-07 195 13-May-07 196 14-May-07 197 15-May-07 9.6 9.8 9.8 25.9 24.0 26.8 28.6 24.7 25.4 13.2 12.1 11.1 2.8 2.3 2.3 32.5 33.1 33.2 11.5 12.3 10.1 18.1 21.6 22.5 33.0 34.0 35.3 10.4 8.7 10.8 0.7 2.3 1.8 37.6 37.1 37.1 198 16-May-07 28.1 27.2 26.5 13.6 24.1 24.8 22.8 11.3 199 17-May-07 200 18-May-07 13.5 11.3 201 19-May-07 202 20-May-07 203 21-May-07 204 22-May-07 205 23-May-07 206 24-May-07 38.7 36.7 38.9 20.0 24.7 17.1 21.0 63.0 36.8 48.6 24.0 41.3 32.6 11.5 9.1 9.8 9.1 9.1 11.6 18.2 15.5 14.7 31.3 31.7 28.9 13.9 15.5 9.6 9.8 46.4 36.1 42.7 52.8 47.5 51.5 9.7 7.3 6.2 8.0 11.1 12.6 18.5 19.7 16.7 207 25-May-07 208 26-May-07 209 27-May-07 210 28-May-07 39.1 37.1 38.2 19.0 34.8 35.1 34.4 11.7 211 29-May-07 42.0 39.9 41.7 19.2 15.6 21.3 19.8 38.2 52.2 41.5 37.6 26.5 30.1 8.2 7.5 10.3 9.6 12.1 10.6 17.7 15.6 15.5 38.2 37.3 37.9 11.8 6.7 6.7 6.9 34.5 33.8 50.4 41.9 51.6 43.1 5.1 5.1 4.4 10.6 10.6 11.1 18.4 16.5 17.7 mg/L mg/Lmg/g TSS mg/g TSS mg/g TSS mg/Lmg/L mg/L mg/L secondsseconds mg/g TSS mg/g TSS mg/g TSS Humic-like substances carbohydrates protein Humic-like substancesprotein Humic-like substances carbohydrates proteincarbohydrates protein Humic-like substances carbohydrates Bound Soluble Bound Soluble CST EPS CST EPS MEBPR (side-C) MEBPR (side-V) AEROBIC AEROBIC

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