Ng, Tsz Wai. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 86-98). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Abstract --- p.ii / Table of Contents --- p.vii / List of Figures --- p.xiii / List of Plates --- p.XV / List of Tables --- p.xxi / Abbreviations --- p.xxii / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- "Pollution, toxicity and environmental impact of azo dye" --- p.1 / Chapter 1.2 --- Common treatment methods for dyeing effluent --- p.2 / Chapter 1.2.1 --- Physicochemical methods --- p.2 / Chapter 1.2.1.1 --- Coagulation/ flocculation --- p.2 / Chapter 1.2.1.2 --- Adsorption --- p.3 / Chapter 1.2.1.3 --- Membrane filtration --- p.4 / Chapter 1.2.1.4 --- Fenton reaction --- p.4 / Chapter 1.2.1.5 --- Ozonation --- p.5 / Chapter 1.2.1.6 --- Photocatalytic oxidation --- p.6 / Chapter 1.2.2 --- Biological treatments --- p.7 / Chapter 1.2.2.1 --- Degradation of azo dyes by bacteria --- p.8 / Chapter 1.2.2.1.1 --- Anaerobic conditions --- p.8 / Chapter 1.2.2.1.2 --- Aerobic conditions --- p.9 / Chapter 1.2.2.1.3 --- Combined anaerobic and aerobic conditions --- p.10 / Chapter 1.2.2.2 --- Decolourization of azo dyes by fungi --- p.11 / Chapter 1.2.2.3 --- Mechanisms of azo dye reduction by microorganisms --- p.12 / Chapter 1.3 --- "Chromium species, toxicity and their impacts on environment" --- p.14 / Chapter 1.4 --- Common treatment methods for chromium --- p.16 / Chapter 1.4.1 --- Chemical and physical methods --- p.16 / Chapter 1.4.2 --- Biological methods --- p.17 / Chapter 1.4.2.1 --- Chromium reduction by aerobic bacteria --- p.17 / Chapter 1.4.2.2 --- Chromium reduction by anaerobic bacteria --- p.18 / Chapter 1.5 --- Studies concerning azo dye and Cr(VI) co-treatment --- p.19 / Chapter 1.6 --- Response surface methodology --- p.21 / Chapter 1.6.1 --- Response surface methodology against one-factor-at-a-time design --- p.22 / Chapter 1.6.2 --- Phases of response surface methodology --- p.25 / Chapter 1.6.3 --- 2 - level factorial design --- p.26 / Chapter 1.6.4 --- Path of steepest ascent --- p.27 / Chapter 1.6.5 --- Central composite design --- p.28 / Chapter 2. --- Objectives --- p.30 / Chapter 3. --- Materials and Methods --- p.31 / Chapter 3.1 --- Isolation of bacterial strains --- p.31 / Chapter 3.1.2 --- Azo dye decolourization --- p.33 / Chapter 3.1.3 --- Chromate reduction --- p.34 / Chapter 3.2 --- Identification of selected bacterial strains --- p.35 / Chapter 3.2.1 --- Gram stain --- p.35 / Chapter 3.2.2 --- Sherlock® Microbial Identification System --- p.35 / Chapter 3.2.3 --- 16S ribosomal RNA sequencing --- p.37 / Chapter 3.3 --- Optimization of dye decolourization and chromate reduction efficiency with response surface methodology --- p.38 / Chapter 3.3.1 --- Minimal-run resolution V design --- p.38 / Chapter 3.3.2 --- Path of steepest ascent --- p.40 / Chapter 3.3.3 --- Central composite design --- p.41 / Chapter 3.3.4 --- Statistical analysis --- p.43 / Chapter 3.3.5 --- Experimental validation of the optimized conditions --- p.43 / Chapter 3.4 --- Determination of the performance of the selected bacterium in different conditions --- p.43 / Chapter 3.5 --- Determination of azoreductase and chromate reductase activities --- p.44 / Chapter 3.5.1 --- Preparation of cell free extract --- p.44 / Chapter 3.5.2 --- Azoreductase and chromate reductase assay --- p.45 / Chapter 3.6 --- Determination and characterization of degradation intermediates --- p.45 / Chapter 3.6.1 --- Isolation and concentration of the purple colour degradation intermediate --- p.45 / Chapter 3.6.2 --- Mass spectrometry analysis --- p.47 / Chapter 3.6.3 --- Atomic absorption spectrometry analysis --- p.48 / Chapter 4. --- Results --- p.49 / Chapter 4.1 --- Azo dye decolourizing and chromate reducing ability of the isolated bacterial strain --- p.49 / Chapter 4.2 --- Identification of selected bacterium --- p.50 / Chapter 4.3 --- Optimization of dye decolourization and chromate reduction efficiency with response surface methodology --- p.50 / Chapter 4.3.1 --- Minimal-run resolution V design --- p.50 / Chapter 4.3.2 --- Path of the steepest ascend --- p.54 / Chapter 4.3.3 --- Central composite design --- p.55 / Chapter 4.3.4 --- Validation of the predicted model --- p.62 / Chapter 4.4 --- Performance of the selected bacterium in different conditions --- p.62 / Chapter 4.4.1 --- Chromate and dichromate --- p.62 / Chapter 4.4.2 --- Initial pH --- p.63 / Chapter 4.4.3 --- Low and high salt concentration --- p.63 / Chapter 4.4.4 --- Initial K2CrO4 concentration --- p.63 / Chapter 4.4.5 --- Initial Acid Orange 7 concentration --- p.63 / Chapter 4.4.6 --- Nutrients limitation --- p.64 / Chapter 4.5 --- Chromate reductase and azoreductase activities --- p.67 / Chapter 4.6 --- Determination of degradation intermediates --- p.67 / Chapter 4.6.1 --- Mass spectrum of the degradation intermediate --- p.68 / Chapter 4.6.2 --- Chromium content of the degradation intermediate --- p.70 / Chapter 5. --- Discussion --- p.71 / Chapter 5.1 --- Characteristic of Brevibacterium linens --- p.71 / Chapter 5.2 --- Optimization of dye decolourization and chromate reduction with response surface methodology --- p.72 / Chapter 5.3 --- Performance of Brevibacterium linens under different culture conditions --- p.75 / Chapter 5.4 --- Postulation of mechanisms --- p.76 / Chapter 5.4.1 --- Possible reasons of unexpected results of the effect of initial Acid Orange 7 and K2CrO4 concentration --- p.76 / Chapter 5.4.2 --- Properties of the purple colour degradation intermediate --- p.78 / Chapter 5.4.3 --- Mechanisms likely responsible for the chromate reduction --- p.80 / Chapter 5.4.4 --- Explanation of the unexpected results --- p.80 / Chapter 6. --- Conclusions --- p.83 / Chapter 7. --- References --- p.86 / Chapter 8. --- Appendices --- p.99 / Chapter 8.1 --- Definition and calculation of different terms in 2-level factorial design --- p.99 / Chapter 8.2 --- Definition and calculation of different terms in ANOVA table --- p.100 / Chapter 8.3 --- Aliases of terms and resolution --- p.103 / Chapter 8.4 --- Moving of factors in path of steepest ascent --- p.105 / Chapter 8.5 --- Estimation of the parameters in linear regression models --- p.106 / Chapter 8.6 --- Definition and calculation of different terms in test of fitness --- p.109

Cai, Qinhong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 142-166). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Abstract --- p.ii / Table of contents --- p.viii / List of figures --- p.xv / List of plates --- p.xix / List of tables --- p.xxi / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Pollution generated from dyeing industry --- p.1 / Chapter 1.2 --- Occurrence and pollution of chromium azo dyes --- p.2 / Chapter 1.3 --- Common treatment methods for dyeing effluents --- p.7 / Chapter 1.3.1 --- Physicochemical methods --- p.7 / Chapter 1.3.2 --- Chemical methods --- p.9 / Chapter 1.3.2.1 --- Ozonation --- p.10 / Chapter 1.3.2.2 --- Fenton reaction --- p.11 / Chapter 1.3.2.3 --- Sodium hypochlorite (NaOCl) --- p.12 / Chapter 1.3.2.4 --- Photocatalytic oxidation (PCO) --- p.13 / Chapter 1.3.3 --- Physical methods --- p.14 / Chapter 1.3.3.1 --- Adsorption --- p.14 / Chapter 1.3.3.2 --- Membrane filtration --- p.15 / Chapter 1.3.4 --- Biological treatments --- p.16 / Chapter 1.3.4.1 --- Decolorization of azo dyes by bacteria --- p.16 / Chapter 1.3.4.1.1 --- Under anaerobic conditions --- p.18 / Chapter 1.3.4.1.2 --- Under anoxic conditions --- p.19 / Chapter 1.3.4.1.3 --- Under aerobic conditions --- p.21 / Chapter 1.3.4.2 --- Mechanisms of azo dye reduction by bacteria --- p.23 / Chapter 1.3.4.3 --- Decolorization of azo dyes by fungi and algae --- p.27 / Chapter 1.4 --- Chromium species and their impacts on environment --- p.27 / Chapter 1.4.1 --- Chromium toxicology and speciation --- p.28 / Chapter 1.4.2 --- Common treatment methods for chromium --- p.31 / Chapter 1.5 --- Studies concerning treatment of chromium azo dyes --- p.32 / Chapter 1.6 --- Response surface methodology (RSM) --- p.33 / Chapter 1.6.1 --- RSM vs. one factor-at-a-time (OFAT) design --- p.36 / Chapter 1.6.2 --- Phases of RSM --- p.39 / Chapter 1.6.3 --- Two level factorial design --- p.40 / Chapter 1.6.4 --- Path of steepest ascent (PSA) --- p.43 / Chapter 1.6.5 --- Central composite design (CCD) --- p.44 / Chapter 1.6.6 --- Estimation of the parameters in linear regression models --- p.45 / Chapter 1.6.7 --- Test of fitness --- p.47 / Chapter 2. --- Objectives and significance of the project --- p.49 / Chapter 3. --- Materials and methods --- p.50 / Chapter 3.1 --- Chemicals --- p.50 / Chapter 3.1.1 --- Chemicals for preparation of bacterial culture media --- p.50 / Chapter 3.1.2 --- Chemicals for identification of bacteria --- p.50 / Chapter 3.1.3 --- Chemicals for chromium speciation --- p.51 / Chapter 3.1.4 --- Chemicals for immobilization of bacterial cells --- p.52 / Chapter 3.2 --- Sludge samples --- p.53 / Chapter 3.3 --- Characterization of Acid Yellow 99 --- p.54 / Chapter 3.4 --- Monitor of azo dye decolorization --- p.55 / Chapter 3.5 --- "Isolation of bacterial strains, which can degrade Acid Yellow 99" --- p.55 / Chapter 3.6 --- Identification of selected bacterial strains --- p.58 / Chapter 3.6.1 --- Gram stain --- p.58 / Chapter 3.6.2 --- Sherlock® microbial identification system --- p.58 / Chapter 3.6.3 --- Biolog® microstation system --- p.59 / Chapter 3.6.4 --- Selection of the most effective bacterial strains --- p.59 / Chapter 3.6.5 --- 16S ribosomal RNA sequencing --- p.60 / Chapter 3.7 --- Chromium speciation with interferences of chromium organic complexes --- p.60 / Chapter 3.7.1 --- Instrumentation --- p.60 / Chapter 3.7.2 --- Column preparation --- p.61 / Chapter 3.7.3 --- Determination of percentage retained and recovery --- p.62 / Chapter 3.7.4 --- "Speciation of Cr(VI), ionic Cr(III) and chromium azo dye" --- p.63 / Chapter 3.7.4 --- Preparation of Cr(III)-organic complexes --- p.65 / Chapter 3.7.5 --- Preparation of a microbial degraded chromium azo dye sample --- p.65 / Chapter 3.8 --- Chromium distribution in a treated solution --- p.66 / Chapter 3.9 --- Distribution of AY99 in a treated solution --- p.68 / Chapter 3.10 --- Optimization of decolorization process with response surface methodology (RSM) --- p.70 / Chapter 3.10.1 --- Correlation of cell mass and cell density of selected bacteria --- p.70 / Chapter 3.10.2 --- Preliminary investigation of the optimum conditions --- p.70 / Chapter 3.10.3 --- Minimal run resolution V (MR5) design --- p.71 / Chapter 3.10.4 --- Path of steepest ascent (PSA) --- p.74 / Chapter 3.10.5 --- Central composite design (CCD) and RSM --- p.75 / Chapter 3.10.6 --- Statistical analysis --- p.76 / Chapter 3.10.7 --- Experimental validation of the optimized conditions --- p.77 / Chapter 3.11 --- Immobilization of bacterial cells --- p.77 / Chapter 3.11.1 --- Immobilization by polyvinyl alcohol (PVA) gels --- p.77 / Chapter 3.11.2 --- Immobilization by polyacrylamide gels --- p.78 / Chapter 3.11.3 --- Performance of immobilized cells and free cells --- p.79 / Chapter 3.11.5 --- Storage stabilities of immobilized cells and free cells --- p.80 / Chapter 3.12 --- Performance of a laboratory scale bioreactor --- p.80 / Chapter 3.12.1 --- Chromium distribution in the bioreactor --- p.82 / Chapter 3.12.2 --- Distribution of AY99 in the bioreactor --- p.82 / Chapter 3.12.3 --- Fourier transform infrared spectroscopy (FT-IR) analysis of suspended particles in the treated solution --- p.84 / Chapter 4. --- Results --- p.85 / Chapter 4.1 --- Characterization of AY99 --- p.85 / Chapter 4.2 --- Identification of isolated bacterial strains --- p.86 / Chapter 4.3 --- Selection of the most effective bacterial strains --- p.89 / Chapter 4.4 --- Chromium speciation with interferences of chromium organic complexes --- p.91 / Chapter 4.4.1 --- Effect of pH --- p.91 / Chapter 4.4.2 --- Speciation of Cr(VI)，ionic Cr(III) and chromium azo dye --- p.92 / Chapter 4.4.3 --- Effect of other Cr(III)-organic complexes --- p.93 / Chapter 4.4.4 --- Limit of detection --- p.94 / Chapter 4.4.5 --- Capacity of Amberlite XAD-4 resin --- p.94 / Chapter 4.4.6 --- Determination of Cr(VI) in a microbial degraded chromium azo dye solution --- p.95 / Chapter 4.5 --- Chromium distribution in a free cells treated solution --- p.95 / Chapter 4.6 --- Distribution of AY99 in free cells treated solution --- p.96 / Chapter 4.7 --- Optimization of decolorization process with RSM --- p.98 / Chapter 4.7.1 --- Correlation of cell mass and cell density of selected bacteria --- p.98 / Chapter 4.7.2 --- MR5 design --- p.100 / Chapter 4.7.3 --- Path of steepest ascent (PSA) --- p.102 / Chapter 4.7.4 --- Central composite design (CCD) and RSM --- p.103 / Chapter 4.8 --- Immobilization of bacterial cells --- p.106 / Chapter 4.8.1 --- Performance of immobilized cells and free cells --- p.106 / Chapter 4.8.2 --- Storage stabilities of immobilized cells and free cells --- p.108 / Chapter 4.9 --- Performance of the laboratory scale bioreactor --- p.108 / Chapter 4.9.1 --- Treatment efficiencies of the bioreactor --- p.108 / Chapter 4.9.2 --- Performance stability of the bioreactor in 5 consecutive runs --- p.111 / Chapter 4.9.3 --- Chromium distribution in the bioreactor --- p.114 / Chapter 4.9.4 --- Distribution of AY99 in the bioreactor --- p.115 / Chapter 4.9.5 --- FT-IR analysis of suspended particles in the treated solution --- p.115 / Chapter 5. --- Discussion --- p.117 / Chapter 5.1 --- Chromium speciation with interferences of chromium organic complexes --- p.117 / Chapter 5.2 --- Chromium distribution --- p.117 / Chapter 5.3 --- Distribution of AY99 --- p.122 / Chapter 5.4 --- Optimization of decolorization process with RSM --- p.124 / Chapter 5.4.1 --- MR5 design --- p.124 / Chapter 5.4.2 --- Path of steepest ascent (PSA) --- p.125 / Chapter 5.4.3 --- Central composite design (CCD) and RSM --- p.126 / Chapter 5.5 --- Immobilization of bacterial cells --- p.126 / Chapter 5.5.1 --- Performance of immobilized cells and free cells --- p.126 / Chapter 5.5.2 --- Storage stability of immobilized cells and free cells --- p.128 / Chapter 5.6 --- Performance of the laboratory scale bioreactor --- p.130 / Chapter 5.6.1 --- Treatment efficiencies of the bioreactor --- p.130 / Chapter 5.6.2 --- Performance stability of the bioreactor in 5 consecutive runs --- p.131 / Chapter 5.6.3 --- FT-IR analysis of suspended particles in the treated solution --- p.132 / Chapter 5.6.4 --- Post treatments of bioreactor treated effluents / Chapter 6. --- Conclusions --- p.136 / Chapter 7. --- References --- p.142