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The Effect of Physicochemical Properties of Wastewater Flocs on UV Disinfection Following Hydrodynamic Particle Breakage

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The Effect of Physicochemical Properties of Wastewater Flocs on UV Disinfection Following Hydrodynamic Particle Breakage The Effect of Physicochemical Properties of Wastewater Flocs on UV Disinfection Following Hydrodynamic Particle Breakage by Robert Best A Thesis Presented to The University of Guelph In partial fulfilment of requirements for the degree of Master of Science in Environmental Science Guelph, Ontario, Canada © Robert Best, November, 2012 ABSTRACT THE EFFECT OF PHYSICOCHEMICAL PROPERTIES OF WASTEWATER FLOCS ON UV DISINFECTION FOLLOWING HYDRODYNAMIC PARTICLE BREAKAGE Robert Best Co-Advisors: Professor Marc Habash University of Guelph, 2012 Professor Steven Liss This study showed that hydrodynamic particle breakage had potential as a method to help improve the disinfection of wastewater effluents. The physicochemical properties of flocs from four distinct effluents sources (combined sewer overflow, settled combined sewer overflow, primary effluent, and final effluent) were compared before and after hydrodynamic treatment. The use of hydrodynamic force to cause floc breakage was shown to be effective, though variable, across all source types. This variation in floc breakage did not have a significant impact on the UV disinfection achieved, as the UV dose kinetics were similar across samples from the same source type. The results of this study demonstrate how the physicochemical properties of floc are affected when exposed to shear force. These observations further the understanding of floc composition and behaviour when shear forces are applied while also providing evidence to indicate this process improves the performance of UV disinfection technology. ACKNOWLEDGEMENTS I would first like to offer my sincere thanks and gratitude to my supervisors, Dr. Steven Liss and Dr. Marc Habash. Your guidance, expertise, and the freedom you granted me has helped me grow as not only a scientist, but also as a person. Steven, thank you for supporting me these past two years and for allowing me the opportunity to travel and network with other young professionals. Marc, thank you for your generosity, both in terms of lab space and your time. Your door was always open to me, and for that, I am grateful. To my colleagues at Environment Canada, I would like to thank both Dr. Ian Droppo and John Gibson. Ian, your guidance and insightful comments over the course of this project have pushed me to further my understanding of the impact of this research. John, your assistance with sample preparation and helping me stay sane during the springtime, will be forever remembered. Thank you for all your contributions to this project. To my lab mates Dr. Sandra Tirado, Bailey Davis, and Patrick Soo: Thank you for your encouragement, opinions, and stories over the past couple of years. Without your support this journey would have been much more difficult. To my parents, Peter and Cynthia Best: I would like to thank you for your continued support and encouragement throughout my entire academic career. To my brother Lincoln: without your advice and support, I would not be where am I today or who I am as a person. To my partner Danielle, I love you and cherish your companionship. iii Table of Contents ABSTRACT ..................................................................................................................................... 2 ACKNOWLEDGEMENTS ........................................................................................................ III TABLE OF CONTENTS ............................................................................................................ IV LIST OF TABLES ..................................................................................................................... VII LIST OF FIGURES ................................................................................................................. VIII LIST OF ABBREVIATIONS ..................................................................................................... XI CHAPTER 1: LITERATURE REVIEW ..................................................................................... 1 1.1 INTRODUCTION .................................................................................................................. 1 1.2 WASTEWATER SYSTEMS .................................................................................................... 2 1.2.1 Combined Sewer Overflow ......................................................................................... 2 1.2.2 Wastewater Treatment Plants..................................................................................... 4 1.3 MICROBIAL FLOC STRUCTURE ........................................................................................ 16 1.4 MICROBIAL FLOC SURFACE PROPERTIES ........................................................................ 20 1.4.1 Extracellular Polymeric Substances ......................................................................... 20 1.4.2 Relative Hydrophobicity ........................................................................................... 23 1.4.3 Surface Charge ......................................................................................................... 24 1.5 WATER-BORNE PATHOGENS ........................................................................................... 25 1.6 HYDRODYNAMIC PARTICLE BREAKAGE .......................................................................... 27 1.7 OBJECTIVES ..................................................................................................................... 33 1.7.1 Hypothesis ................................................................................................................ 33 1.7.2 Objectives ................................................................................................................. 33 CHAPTER 2: MATERIALS AND METHODS ........................................................................ 35 iv 2.1 SAMPLE COLLECTION ...................................................................................................... 35 2.2 HYDRODYNAMIC TREATMENT......................................................................................... 37 2.3 PARTICLE COUNTING ....................................................................................................... 38 2.4 ULTRAVIOLET RADIATION DISINFECTION ....................................................................... 39 2.5 SAMPLE PREPARATION AND EXTRACTION PROTOCOL ................................................... 40 2.5.1 Concentration Protocol for Samples ........................................................................ 40 2.5.2 Extraction of Extracellular Polymeric Substances ................................................... 41 2.6 ANALYSIS OF EXTRACELLULAR POLYMERIC SUBSTANCES ............................................ 43 2.6.1 Protein Measurement ............................................................................................... 43 2.6.2 Carbohydrate Measurement ..................................................................................... 44 2.6.3 Acidic Polysaccharide Measurement ....................................................................... 44 2.6.4 Humic Acid Measurement ........................................................................................ 45 2.7 WASTEWATER FLOC PHYSICAL CHARACTERISTICS ........................................................ 46 2.7.1 Relative Hydrophobicity Measurement .................................................................... 46 2.7.2 Surface Charge Measurement .................................................................................. 47 2.8 STATISTICAL ANALYSIS ................................................................................................... 48 CHAPTER 3: RESULTS ............................................................................................................. 50 3.1 FLOC BREAKAGE ............................................................................................................. 50 3.2 PHYSICOCHEMICAL PROPERTIES OF FLOC ....................................................................... 51 3.2.1 Floc Physicochemical Properties ............................................................................. 51 3.2.2 Protein ...................................................................................................................... 55 3.2.3 Carbohydrate ............................................................................................................ 57 3.2.4 Humic Acid ............................................................................................................... 59 3.2.5 Acidic Polysaccharide .............................................................................................. 61 3.2.6 Relative Hydrophobicity ........................................................................................... 63 v 3.2.7 Surface Charge ......................................................................................................... 65 3.3 ULTRAVIOLET DISINFECTION .......................................................................................... 67 CHAPTER 4: DISCUSSION ....................................................................................................... 73 4.1 PHYSICOCHEMICAL PROPERTIES OF FLOC ....................................................................... 73 4.2 HYDRODYNAMIC TREATMENT......................................................................................... 77 4.3 ULTRAVIOLET RADIATION DISINFECTION ......................................................................
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