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Integrated chromate reduction and azo dye degradation by bacterium.

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

Identiferoai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_327003
Date January 2010
ContributorsNg, Tsz Wai., Chinese University of Hong Kong Graduate School. Division of Life Sciences.
Source SetsThe Chinese University of Hong Kong
LanguageEnglish, Chinese
Detected LanguageEnglish
TypeText, bibliography
Formatprint, xviii, 112 leaves : ill. (some col.) ; 30 cm.
RightsUse of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/)

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