Using Coagulation and Dissolved Air Flotation to Treat Algae-Laden Water by Kaiyao Gu A Thesis presented to The University of Guelph In partial fulfilment of requirements for the degree of Master of Science in Engineering Guelph, Ontario, Canada © Kaiyao Gu, December, 2017 Abstract Using Coagulation and Dissolved Air Flotation to Treat Algae-Laden Water Kaiyao Gu Advisor: Professor Hongde Zhou University of Guelph, 2017 Algae inhabit in natural lakes and rivers. They often cause the clogging of filters, increase chemical costs and produce disinfection by-products (DBPs). Many methods have been used to remove algae in water treatment industry, among which are coagulation treatment and dissolved air flotation (DAF). The objectives of this study were to evaluate the performance of coagulation and DAF in treating algae-laden water. A series of experiments were conducted to study the effectiveness of coagulation and dissolved air flotation on removing Chlorella, Merismopedia, Microcystis and Aulacoseira by varying the coagulant dosage and water quality. The process performance was assessed by measuring turbidity, UV absorbance and TOC. Result showed 254 that both two treatment methods could achieve over 80% algae removal. Moreover, the single- cell algae with oval shape were easier to be removed using coagulation process while DAF showed high cell removal efficiency for algae that form rectangular colonies. ACKNOWLEDGEMENTS First of all, I would like to thank Dr. Hongde Zhou for his great help throughout the entire project. I couldn’t finish the experiments without his insight and guidance. Every time I had a trouble about my research, Dr. Zhou always provided useful suggestions that inspired me to solve the problems. I could not imagine a better advisor for my master study. Also, I would like to thank Dr. Sheng Chang who served as my advisory committee member. I am grateful for his help and support for this project. My sincere thank also go to Dr. Andreas Heyland and Dr. Reynald Tremblay, who provided me the opportunity to culture algae in their biological laboratory. They provided me many helps during the algae cultivation. I would thank all my labmates for their great assistance during the experiments: Edwin Castilla Rodriguez, Bei Wang, Yu Hou, Craig Duvall and David Rogala. Especially Edwin, who co- worked with me during coagulation experiments, gave me many advices on testing procedures. I also appreciated Joanne Ryks, Phil Watson and other university staff for their support and assistance. Finally, I would like to thank my family: my parents Jianguo Gu, Chao Ya and my wife Yawen Fan for keeping support and encouragement throughout my life. iii Table of Contents 1 Introduction ............................................................................................................................. 1 1.1 Problems caused by algae ................................................................................................ 1 1.2 Current status in treating algae-laden water ..................................................................... 1 2 Literature review ...................................................................................................................... 3 2.1 Algae contaminated water sources ................................................................................... 3 2.1.1 Algae bloom distribution .......................................................................................... 3 2.1.2 Cyanobacteria, chlorophyta and diatom ................................................................... 4 2.1.3 Algae characteristics ................................................................................................. 6 2.2 Processes to remove algae from water ............................................................................. 9 2.2.1 Coagulation ............................................................................................................... 9 2.2.2 Dissolved air floatation ........................................................................................... 14 3 Research Objectives .............................................................................................................. 17 4 Methodology .......................................................................................................................... 19 4.1 Materials ......................................................................................................................... 19 4.1.1 Raw water sampling ................................................................................................ 19 4.1.2 Algae cultivation ..................................................................................................... 21 4.1.3 Chemicals ................................................................................................................ 26 4.2 Coagulation .................................................................................................................... 28 iv 4.2.1 Experimental set-up ................................................................................................ 28 4.2.2 Operating procedure................................................................................................ 29 4.2.3 Sampling ................................................................................................................. 30 4.3 Dissolved air flotation .................................................................................................... 30 4.3.1 Experimental set-up ................................................................................................ 30 4.3.2 Operating procedure................................................................................................ 31 4.3.3 Sampling ................................................................................................................. 33 4.4 Experimental plan .......................................................................................................... 33 4.5 Analysis .......................................................................................................................... 34 4.5.1 Algae cell counting ................................................................................................. 34 4.5.2 Routine water quality analysis ................................................................................ 36 4.6 QC/QA ........................................................................................................................... 36 5 Results and Discussion .......................................................................................................... 38 5.1 Algae and diatom growth ............................................................................................... 38 5.1.1 Chlorella ................................................................................................................. 38 5.1.2 Merismopedia ......................................................................................................... 40 5.1.3 Aulacoseira ............................................................................................................. 42 5.1.4 Microystis ................................................................................................................ 43 5.1.5 Algae cell density under steady state conditions .................................................... 45 5.2 Individual species in de-ionized water ........................................................................... 46 v 5.2.1 Jar test results .......................................................................................................... 47 5.2.2 Comparison between coagulants............................................................................. 53 5.3 Mixed species in de-ionized water ................................................................................. 56 5.3.1 Coagulation ............................................................................................................. 56 5.3.2 Dissolved air flotation ............................................................................................. 58 5.4 Mixed species in river water .......................................................................................... 60 5.4.1 Coagulation ............................................................................................................. 61 5.4.2 Dissolved air flotation ............................................................................................. 79 6 Conclusions and Recommendations ...................................................................................... 85 6.1 Conclusions .................................................................................................................... 85 6.2 Recommendations .......................................................................................................... 86 7 References ............................................................................................................................. 87 8 APPENDICES ....................................................................................................................... 98 vi List of Figures Figure 2-1 Distribution of documented HAB outbreaks in North America ................................... 3 Figure 4-1 Raw river water smapling location ............................................................................. 19 Figure 4-2 Stationary stage algae in the cultivation system ......................................................... 24 Figure 4-3 Cultivation condition during stationary stage ............................................................. 25 Figure 4-4 Jar test set-up ............................................................................................................... 29 Figure 4-5 DAF set-up .................................................................................................................. 31 Figure 4-6 Neubaueer chamber details ......................................................................................... 34 Figure 5-1 Chlorella cultivation data ............................................................................................ 38 Figure 5-2 Chlorella cell density versus turbidity and dryweight standard curve ........................ 39 Figure 5-3 Merismopedia cultivation data .................................................................................... 40 Figure 5-4 Merismopedia cell density versus turbidity and dryweight standard curve ................ 41 Figure 5-5 Aulacoseira cultivation data ........................................................................................ 42 Figure 5-6 Microcystis cultivation data ........................................................................................ 43 Figure 5-7 Microcystis cell density versus turbidity and dryweight standard curve .................... 44 Figure 5-8 Algae cell counting, turbidity and dry weight at steadt state ...................................... 45 Figure 5-9 Deionized algae-laden water turbidity removal using aluminum sulfate ................... 47 Figure 5-10 Deionized algae-laden water turbidity removal using ferric sulfate ......................... 49 Figure 5-11 Deionized algae-laden water turbidity removal using poly-ferric sulfate ................. 51 Figure 5-12 Coagulant dosage required to achieve 90% removal for Chlorella and Microcystis 53 Figure 5-13 Coagulant dosage required to achieve 60% removal for Merismopedia and Aulacoseira ................................................................................................................ 54 Figure 5-14 Turbidity removal from mixed algae-laden water .................................................... 56 vii Figure 5-15 Turbidity removal from high hardness river water using aluminum sulfate ............. 61 Figure 5-16 Low hardness river water turbidity removal using aluminum sulfate....................... 62 Figure 5-17 High hardness river water TOC&UV removal using aluminum sulfate ................... 64 Figure 5-18 Low hardness river water TOC&UV removal using aluminum sulfate ................... 65 Figure 5-19 High hardness river water turbidity removal using ferric sulfate ............................. 66 Figure 5-20 Low hardness river water turbidity removal using ferric sulfate .............................. 67 Figure 5-21 High hardness river water TOC&UV removal using ferric sulfate .......................... 68 Figure 5-22 Low hardness river water TOC&UV removal using ferric sulfate ........................... 69 Figure 5-23 High hardness river water turbidity removal using PACl ......................................... 70 Figure 5-24 Low hardness river water turbidity removal using PACl.......................................... 71 Figure 5-25 High hardness river water TOC&UV removal using PACl ...................................... 72 Figure 5-26 Low hardness river water TOC&UV removal using PACl ...................................... 73 Figure 5-27 High hardness river water turbidity removal using PFS ........................................... 74 Figure 5-28 Low hardness river water turbidity removal using PFS ............................................ 75 Figure 5-29 High hardness river water TOC&UV removal using PFS ........................................ 76 Figure 5-30 Low hardness river water TOC&UV removal using PFS ......................................... 77 Figure 5-31 Effects of coagulant doses on DAF performance using aluminum sulfate ............... 79 Figure 5-32 Dosage influence on DAF performance using PACl ................................................ 80 Figure 5-33 pH influence on DAF performance using PACl ....................................................... 81 Figure 5-34 Dosage influence on DAF performance using PACl with modified water ............... 82 Figure 5-35 pH influence on DAF performance using PACl with modified water ...................... 83 Figure 5-36 Additional tests with high hardness water ................................................................ 84 viii List of Tables Table 2-1 Comparison of Cyanobacteria, Chlorophyta and Diatom characteristics ...................... 6 Table 2-2 Comparison of test algae characteristics ........................................................................ 9 Table 2-3 Examples of algae removal using conventional water treatment processes ................. 11 Table 2-4 Characteristics of different coagulants used in this study ............................................ 13 Table 2-5 Summary of DAF operating parameters ....................................................................... 15 Table 2-6 Examples of DAF processes ......................................................................................... 16 Table 4-1 Analyltical methods for test water samples .................................................................. 20 Table 4-2 Composition of algae-spiked water .............................................................................. 21 Table 4-3 Cultivation condition during initial and exponential stages ......................................... 22 Table 4-4 Components of cultivation system ............................................................................... 23 Table 4-5 Composition of BBM medium ..................................................................................... 26 Table 4-6 Composition of BG-11 medium ................................................................................... 27 Table 4-7 Composition of CHU-10 medium ................................................................................ 27 Table 4-8 Main characteristics of coagulants used in this study .................................................. 28 Table 4-9 Experimental plan for coagulation tests ....................................................................... 33 Table 4-10 Experimental plan for DAF tests ................................................................................ 34 ix List of Abbreviations AOM Algal organic matter C Solubility of air r DBPs Disinfection by-products EOM Extracellular organic matter DAF Dissolved air flotation HAB Harmful algal bloom IOM Intracellular organic matter K Henry's law solubility constant for nitrogen n K Henry's law solubility constant for oxygen o MIB 2-Methylisoborneol NOM Natural organic matter P Partial pressure of nitrogen n P Partial pressure of oxygen o TOC Total organic carbon T&O Taste and odor x