Cheng Yee Wan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 95-112). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Abstract --- p.ii / Table of Contents --- p.vi / List of Figures --- p.xi / List of Plates --- p.xiv / List of Tables --- p.xvi / Abbreviations --- p.xviii / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Legionella pneumophila --- p.1 / Chapter 1.1.1 --- Bacterial morphology and ultrastructure --- p.2 / Chapter 1.1.2 --- Microbial ecology and natural habitats --- p.4 / Chapter 1.1.2.1 --- Association with amoeba --- p.5 / Chapter 1.1.2.2 --- Association with biofilm --- p.5 / Chapter 1.2 --- Legionnaires' disease and clinical significance --- p.6 / Chapter 1.2.1 --- Epidemiology --- p.6 / Chapter 1.2.1.1 --- Worldwide distribution --- p.6 / Chapter 1.2.1.2 --- Local situation --- p.7 / Chapter 1.2.2 --- Clinical presentation --- p.7 / Chapter 1.2.3 --- Route of infection and pathogenesis --- p.8 / Chapter 1.2.4 --- Diagnosis --- p.10 / Chapter 1.2.4.1 --- Culture of Legionella --- p.10 / Chapter 1.2.4.2 --- Direct fluorescent antibody (DFA) staining --- p.13 / Chapter 1.2.4.3 --- Serologic tests --- p.13 / Chapter 1.2.4.4 --- Urine antigen testing --- p.14 / Chapter 1.2.4.5 --- Detection of Legionella nucleic acid --- p.15 / Chapter 1.2.5 --- Risk factors --- p.15 / Chapter 1.2.6 --- Treatment for Legionella infection --- p.16 / Chapter 1.3 --- Detection of Legionella in environment --- p.16 / Chapter 1.4 --- Disinfection methods --- p.17 / Chapter 1.4.1 --- Physical methods --- p.19 / Chapter 1.4.1.1 --- Filtration --- p.19 / Chapter 1.4.1.2 --- UV-C irradiation --- p.20 / Chapter 1.4.1.3 --- Thermal eradication (superheat-and-flush) --- p.21 / Chapter 1.4.2 --- Chemical methods --- p.21 / Chapter 1.4.2.1 --- Chlorination --- p.21 / Chapter 1.4.2.2 --- Copper-silver ionization --- p.22 / Chapter 1.4.3 --- Effect of biofilm and other factors on disinfection --- p.23 / Chapter 1.5 --- Photocatalytic oxidation (PCO) --- p.24 / Chapter 1.5.1 --- Generation of strong oxidants --- p.24 / Chapter 1.5.2 --- Disinfection mechanism(s) --- p.27 / Chapter 1.5.3 --- Major factors affecting the process --- p.28 / Chapter 2. --- Objectives --- p.30 / Chapter 3. --- Materials and Methods --- p.31 / Chapter 3.1 --- Chemicals --- p.31 / Chapter 3.2 --- Bacterial strains and culture --- p.31 / Chapter 3.3 --- Photocatalytic reactor --- p.33 / Chapter 3.4 --- PCO efficacy tests --- p.33 / Chapter 3.5 --- PCO sensitivity tests --- p.35 / Chapter 3.6 --- Optimisation of PCO conditions --- p.35 / Chapter 3.6.1 --- Optimization of TiO2 concentration --- p.36 / Chapter 3.6.2 --- Optimization of UV intensity --- p.36 / Chapter 3.6.3 --- Optimization of depth of reaction mixture --- p.36 / Chapter 3.6.4 --- Optimization of stirring rate --- p.37 / Chapter 3.6.5 --- Optimization of initial pH --- p.37 / Chapter 3.6.6 --- Optimization of treatment time and initial cell concentration --- p.37 / Chapter 3.6.7 --- Combinational optimization --- p.37 / Chapter 3.7 --- Transmission electron microscopy (TEM) --- p.38 / Chapter 3.8 --- Fatty acid profile analysis --- p.40 / Chapter 3.9 --- Total organic carbon (TOC) analysis --- p.42 / Chapter 3.10 --- UV-C irradiation --- p.44 / Chapter 3.11 --- Hyperchlorination --- p.44 / Chapter 3.12 --- Statistical analysis and replication --- p.45 / Chapter 3.13 --- Safety precautions --- p.45 / Chapter 4. --- Results --- p.46 / Chapter 4.1 --- Efficacy test --- p.46 / Chapter 4.2 --- PCO sensitivity --- p.47 / Chapter 4.3 --- Optimization of PCO conditions --- p.48 / Chapter 4.3.1 --- TiO2 concentration --- p.48 / Chapter 4.3.2 --- UV intensity --- p.48 / Chapter 4.3.3 --- Depth of reaction mixture --- p.51 / Chapter 4.3.4 --- Stirring rate --- p.56 / Chapter 4.3.5 --- Effect of initial pH --- p.56 / Chapter 4.3.6 --- Effect of treatment time and initial concentrations --- p.56 / Chapter 4.3.7 --- Combinational effects --- p.63 / Chapter 4.4 --- Transmission electron microscopy (TEM) --- p.66 / Chapter 4.4.1 --- Morphological changes induced by PCO --- p.66 / Chapter 4.4.2 --- Comparisons with changes caused by UV-C irradiation and chlorination --- p.67 / Chapter 4.5 --- Fatty acid profile analysis --- p.71 / Chapter 4.6 --- Total organic carbon (TOC) analysis --- p.73 / Chapter 4.7 --- UV-C irradiation --- p.74 / Chapter 4.8 --- Hyperchlorination --- p.74 / Chapter 5. --- Discussion --- p.76 / Chapter 5.1 --- Efficacy test --- p.76 / Chapter 5.2 --- PCO sensitivity --- p.76 / Chapter 5.3 --- Optimization of PCO conditions --- p.77 / Chapter 5.3.1 --- Effect of TiO2 concentration --- p.77 / Chapter 5.3.2 --- Effect of UV intensity --- p.78 / Chapter 5.3.3 --- Effect of depth of reaction mixture --- p.79 / Chapter 5.3.4 --- Effect of stirring rate --- p.79 / Chapter 5.3.5 --- Effect of initial pH --- p.80 / Chapter 5.3.6 --- Effect of treatment time and initial concentrations --- p.81 / Chapter 5.3.7 --- Combinational effect --- p.82 / Chapter 5.4 --- Transmission electron microscopy (TEM) --- p.83 / Chapter 5.4.1 --- Morphological changes induced by PCO --- p.83 / Chapter 5.4.2 --- Comparisons with changes caused by UV-C irradiation and chlorination --- p.85 / Chapter 5.5 --- Fatty acid profile analysis --- p.85 / Chapter 5.6 --- Total organic carbon (TOC) analysis --- p.86 / Chapter 5.7 --- Comparisons of the three disinfection methods --- p.88 / Chapter 6. --- Conclusion --- p.91 / Chapter 7. --- References --- p.95 / Chapter 8. --- Appendix --- p.113

Wong Man Yung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 106-120). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Abstract --- p.ii / Table of Contents --- p.vi / List of Figures --- p.xi / List of Plates --- p.xiii / List of Tables --- p.xv / Abbreviations --- p.xvi / Equations --- p.xviii / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Water disinfection --- p.1 / Chapter 1.2 --- Bacterial species --- p.2 / Chapter 1.2.1 --- Staphylococcus saprophyticus --- p.2 / Chapter 1.2.2 --- Enterobacter cloacae --- p.3 / Chapter 1.3 --- Disinfection methods --- p.4 / Chapter 1.3.1 --- Physical methods --- p.4 / Chapter 1.3.1.1 --- UV-C irradiation --- p.4 / Chapter 1.3.1.2 --- Solar disinfection --- p.5 / Chapter 1.3.2 --- Chemical methods --- p.6 / Chapter 1.3.2.1 --- Chlorination --- p.6 / Chapter 1.3.2.2 --- Ozonation --- p.7 / Chapter 1.3.2.3 --- Mixed disinfectants --- p.8 / Chapter 1.3.3 --- Other disinfection methods --- p.8 / Chapter 1.4 --- Advanced oxidation processes (AOPs) --- p.9 / Chapter 1.5 --- Photocatalytic oxidation (PCO) --- p.10 / Chapter 1.5.1 --- PCO process --- p.12 / Chapter 1.5.2 --- Photocatalysts --- p.14 / Chapter 1.5.2.1 --- Titanium dioxide (P25) --- p.15 / Chapter 1.5.2.2 --- Silver sensitized P25 (Ag/P25) --- p.16 / Chapter 1.5.2.3 --- Silicon dioxide doped titanium dioxide (SiO2-TiO2) --- p.17 / Chapter 1.5.2.4 --- Copper(I) oxide sensitized P25 (Cu2O/P25) --- p.18 / Chapter 1.5.3 --- Irradiation sources --- p.19 / Chapter 1.5.4 --- PCO disinfection mechanisms --- p.20 / Chapter 1.6 --- Bacterial defense mechanisms against oxidative stress --- p.22 / Chapter 2. --- Objectives --- p.25 / Chapter 3. --- Materials and Methods --- p.26 / Chapter 3.1 --- Chemicals --- p.26 / Chapter 3.2 --- Bacterial culture --- p.26 / Chapter 3.3 --- Photocatalytic reactor --- p.27 / Chapter 3.4 --- PCO efficacy test --- p.30 / Chapter 3.5 --- Optimization of PCO conditions --- p.31 / Chapter 3.5.1 --- Effect of P25 concentrations --- p.31 / Chapter 3.5.2 --- Effect of UV intensities --- p.32 / Chapter 3.5.3 --- Combinational study of P25 concentrations and UV intensities --- p.32 / Chapter 3.5.4 --- Effect of stirring rates --- p.32 / Chapter 3.5.5 --- Effect of initial cell concentrations --- p.33 / Chapter 3.6 --- PCO disinfection using different photocatalysts --- p.33 / Chapter 3.6.1 --- Effect of CU2O/P25 concentrations --- p.33 / Chapter 3.6.2 --- Effect of CU2O powder on the two bacterial species --- p.33 / Chapter 3.7 --- Transmission electron microscopy (TEM) --- p.34 / Chapter 3.8 --- Catalase (CAT) test --- p.37 / Chapter 3.9 --- Superoxide dismutase (SOD) activity assay --- p.39 / Chapter 4. --- Results --- p.40 / Chapter 4.1 --- Efficacy test --- p.40 / Chapter 4.2 --- PCO disinfection under UV irradiation --- p.40 / Chapter 4.2.1 --- Control experiments --- p.40 / Chapter 4.2.2 --- Optimization of PCO conditions using P25 as a photocatalyst --- p.42 / Chapter 4.2.2.1 --- Effect of P25 concentrations --- p.42 / Chapter 4.2.2.2 --- Effect of UV intensities --- p.45 / Chapter 4.2.2.3 --- Combinational study of P25 concentrations and UV intensities --- p.48 / Chapter 4.2.2.4 --- Effect of stirring rates --- p.54 / Chapter 4.2.2.5 --- Effect of initial cell concentrations --- p.57 / Chapter 4.2.3 --- Comparison of PCO inactivation efficiency between S. saprophyticus and E. cloacae --- p.60 / Chapter 4.2.4 --- PCO disinfection using different photocatalysts --- p.62 / Chapter 4.2.4.1 --- Control experiments --- p.62 / Chapter 4.2.4.2 --- Ag/P25 --- p.62 / Chapter 4.2.4.3 --- SiO2-TiO2 --- p.64 / Chapter 4.2.4.4 --- Cu2O/P25 --- p.64 / Chapter 4.3 --- PCO disinfection under visible light irradiation --- p.66 / Chapter 4.3.1 --- Effect of Cu2O/P25 concentrations --- p.67 / Chapter 4.3.2 --- Effect of CU2O powder on the two bacterial species --- p.70 / Chapter 4.4 --- Feasibility use of indoor light (fluorescent lamps) for PCO disinfection --- p.71 / Chapter 4.5 --- Transmission electron microscopy (TEM) --- p.74 / Chapter 4.5.1 --- Morphological changes induced by PCO using P25 as a photocatalyst --- p.74 / Chapter 4.5.2 --- Morphological changes induced by PCO using Cu2O/P25 as a photocatalyst --- p.77 / Chapter 4.6 --- Catalase (CAT) test --- p.80 / Chapter 4.7 --- Superoxide dismutase (SOD) activity assay --- p.82 / Chapter 5. --- Discussion --- p.83 / Chapter 5.1 --- Efficacy test --- p.83 / Chapter 5.2 --- PCO disinfection under UV irradiation --- p.83 / Chapter 5.2.1 --- Optimization study --- p.84 / Chapter 5.2.1.1 --- Effect of P25 concentrations --- p.84 / Chapter 5.2.1.2 --- Effect of UV intensities --- p.85 / Chapter 5.2.1.3 --- Combinational study of P25 concentrations and UV intensities --- p.86 / Chapter 5.2.1.4 --- Effect of stirring rates --- p.86 / Chapter 5.2.1.5 --- Effect of initial cell concentrations --- p.87 / Chapter 5.2.2 --- Comparison of PCO inactivation efficiency between S. saprophyticus and E. cloacae --- p.88 / Chapter 5.2.3 --- PCO disinfection using different photocatalysts --- p.89 / Chapter 5.2.3.1 --- Ag/P25 --- p.89 / Chapter 5.2.3.2 --- SiO2-TiO2 and Cu2O/P25 --- p.90 / Chapter 5.3 --- PCO disinfection under visible light irradiation --- p.90 / Chapter 5.3.1 --- Effect of Cu20/P25 concentrations --- p.91 / Chapter 5.3.2 --- Effect of CU2O powder on the two bacterial species --- p.92 / Chapter 5.4 --- Feasibility use of fluorescent lamps for PCO disinfection --- p.93 / Chapter 5.5 --- Transmission electron microscopy (TEM) --- p.95 / Chapter 5.5.1 --- Morphological changes induced by PCO using P25 as a photocatalyst --- p.95 / Chapter 5.5.2 --- Morphological changes induced by PCO using CU2O/P25 as a photocatalyst --- p.96 / Chapter 5.6 --- Catalase (CAT) test --- p.98 / Chapter 5.7 --- Superoxide dismutase (SOD) activity assay --- p.99 / Chapter 6. --- Conclusion --- p.101 / Chapter 7. --- References --- p.106 / Chapter 8. --- Appendix --- p.121

Soil aquifer treatment was simulated in 1 m laboratory soil columns containing silica sand under saturated and unsaturated soil conditions to examine the effect of travel length through the unsaturated zone on the removal of wastewater organic matter, the effect of soil type on dissolved organic carbon removal and also the type of microorganisms involved in the removal process. Dissolved organic carbon removal and nitrification did enhance when the wastewater travelled a longer length through the unsaturated zone. A similar consortium of microorganisms was found to exist in both saturated and unsaturated columns. Microbial concentrations however were lowest in the soil column containing silt and clay in addition to silica sand. The presence of silt and clay was detrimental to DOC removal efficiency under saturated soil conditions due to their negative effect on the hydraulic performance of the soil column and microbial growth.