PhD. (Chemistry) / Please refer to full text to view abstract

PhD. (Chemistry) / Pre-synthesised gadolinium oxide decorated multiwalled carbon nanotubes (MWCNT-Gd) were coupled with titania to form nanocomposite photocatalysts (MWCNT-Gd/TiO2) using a sol-gel method. Rare earth metal ions (Eu, Nd and Gd), nitrogen and sulphur tridoped titania were decorated on MWCNT-Gd to yield composite photocatalysts (MWCNT-Gd/Eu/Nd/Gd/N,S-TiO2) by a similar method, using thiourea as nitrogen and sulphur source. Different carbon nanomaterials were incorporated into tridoped titania to form various composite photocatalysts (MWCNT/Gd,N,S-TiO2, MWCNT/Nd,N,S-TiO2, SWCNT (single walled carbon nanotube)/Nd,N,S-TiO2 and rGO (reduced graphene oxide)/Nd,N,S-TiO2) via the sol-gel method. Likewise, gadolinium doped graphitic carbon nitride (g-C3N4-Gd3+) was obtained by heating a mixture of gadolinium nitrate hexahydrate and cyanoguanidine and subsequently hybridised with MWCNT/TiO2 using the sol-gel method to yield composite photocatalysts with varying g-C3N4-Gd3+ loadings. All the prepared photocatalysts were characterised by microscopic tools (FE/FIB-SEM-EDX, TEM), crystallographic technique (XRD), spectroscopic tools (UV-Vis, Raman and FT-IR) and nitrogen sorption technique (BET).

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy Johannesburg 2012 / Wastes from mining operations usually contain a suite of pollutants, among them cyanide and its complexes; heavy metals; metalloids and radionuclides. The pollution plume can affect public health through contamination of drinking water supplies, aquatic ecosystems and agricultural soils. As such, waste management and remediation has become an important integral component of mining. Conventional chemical and physical methods are often expensive and ineffective when the pollutant concentrations are very high, so the challenge of developing cost-effective materials with high adsorption efficiencies for pollutants still remains. This research was dedicated to the development of biosorbents with high metal loading capacity for the remediation of mine wastewater, namely: zeolite/bentonite functionalised with microbial components such as histidine, cysteine, sorbitol and mannitol; zeolite/bentonite functionalised with Penicillium-simplicissimum and zeolite-alginate complex generated by impregnating natural zeolite into alginate gel beads. The ability of the fresh water algae, Oedogonium sp. to remove heavy metals from aqueous solutions in batch systems was also assessed. Optimum biosorption conditions for the removal of Co, Cu, Cr, Fe, Hg, Ni, Zn and U (in a single-ion and multi-ion systems) were determined as a function of pH, initial concentration, contact time, temperature, and mass of biosorbent. An increase of adsorption capacity was observed following modification of natural zeolite/bentonite by microbial components with a maximum adsorption capacity obtained at low pH. The FTIR results of the developed biosorbents showed that the biomass has different functional groups that are able to react with metal ions in aqueous solution. Immobilisation of fungi (Penicillium-simplicissimum) on zeolite/bentonite yielded biomass of 600 mg g-1 (10-fold higher than the non-immobilised one) at a pH 4, showing the potential of this sorbent towards remediation of AMD-polluted mine sites. The maximum uptake of metals ions (in a multi-ion system) was higher and constant (40-50 mg g-1) in the inactive fungal biomass (heat-killed) from pH 2 to 7. The uptake of U and Hg increased significantly in the zeolite/bentonite-P.simplicissimum compared to their natural forms due to the presence of the N-H, S-H and COO- groups. iii The pseudo second-order adsorption model was found to be more suitable in describing the adsorption kinetics of metal ions onto biomasses in single- and multi-ion systems with the sorption of nickel being controlled by film diffusion processes (with the coefficient values of 10-7 cm2 s-1). The thermodynamic parameters showed that the adsorption onto developed biosorbents was feasible and spontaneous under the studied conditions. The calculated values of the loading capacities in column adsorption for the natural zeolite/bentonite as well as zeolite/bentonite-P.simplicissimum were close to those obtained in the batch tests, mainly for U and Ni. The bed depth service time model (BDST) was used successfully to fit the experimental data for Ni and U adsorbed on the natural zeolite. This suggested a linear relationship between bed depth and service time, which could be used for scale-up purpose. The developed biosorbents could be regenerated using 1 mol L-1 HNO3 solution for potential re-use. The total decrease in biosorption efficiency of zeolite-Penicillium simplicissimum after five cycles of adsorption-desorption was ≤ 5% which showed that zeolite/bentonite-Penicillium simplicissimum had good potential to adsorb metal ions repeatedly from aqueous solution. On applying it to real wastewater samples, the zeolite-P. simplicissimum biosorbent removed 97% of the metals. Penicillium sp. immobilisation enhanced the potential and makes it an attractive bioremediation agent. The zeolite-alginate sorbent exhibited elevated adsorption capacities for metals. This showed potential for use of such a system for remediation purposes. It also provides a platform to explore the possibility of using zeolite in conjunction with other polysaccharide-containing materials for heavy metal removal from wastewaters. The results obtained in this study have shown that zeolite and bentonite are good supports for biomass. The biofunctionalised zeolite/bentonite systems have potential in removal of heavy metals from wastewaters.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Masters of Science, 2017 / The tailoring of zeolites surface properties using organic functionalising agents displaying higher binding affinity for metal ions is a widely explored approach for water treatment. In this study, amine functionalised zeolites and phosphate functionalised zeolites were separately synthesised from similar natural zeolite precursors using reflux methods. The surface composition and morphological elucidations were achieved by characterising the adsorbents using Fourier Transform Infra-red spectroscopy (FTIR), thermogravimetric analysis (TGA), Zeta potential, Point of zero charge (pHPZC), and the Brunauer, Emmett and Teller analysis (BET). In case study 5.1, the sorption mechanisms of the uranyl ion onto amine functionalised zeolites (AMZ), activated carbon (AC) and natural zeolite (NZ) were studied as function of various environmental batch parameters. There was effective adsorption when uranium existed as uranyl ions: UO22+ and UO2OH+. The data fitted numerous kinetic and isotherm models suggesting that the equilibrium mechanisms were characteristic of a combination of chemisorption and physisorption for these three adsorbents. The Dubinin-Radushkevich (DR) model did not fit the data and therefore the energy values derived from it were not used to predict the mechanisms involved. However, the thermodynamic evaluations of parameters ∆H, ΔG and ∆S° showed that equilibrium mechanisms were exothermically, randomly and spontaneously favoured for all adsorbents at temperatures ranging between 22 and 40oC. The adsorption capacity of 0.452 mg g-1 was achieved at pH 3 by 500 mg AC dosage using 20 mL volume of 10 mg L-1 uranyl ion solution after equilibrating for 6 h within the temperature ranges of 22 to 30oC. Under the same conditions of sorbent dosage of 500 mg, uranyl solution volume of 20 mL and 10 mg L-1 U(VI) solution concentration, the maximum adsorption capacity of 0.506 mg g-1 for NZ and 0.480 mg g-1 for AMZ were both achieved at pH 4 after equilibration time of 21 h and 6 h with the optimum temperature range of 22 to 30oC, respectively. The model results predict that intraparticle diffusion thorough pores decreased in the order AC ˃ NZ ˃ AMZ while estimating that chemisorption occurred in a reverse order. On the basis of the modelled data, it was deduced that amine functionalisation of natural zeolites improves their chemisorption capability for uranyl ion and can therefore be used as a cost efficient adsorbent for small-scale remediation of contaminated aquatic systems. In another case study 5.2, the surface properties of successfully prepared aminomethyl phosphonic acid functionalised natural zeolite (APZ) were compared to those of commercial silica polyamine composites (SPC) for uranium uptake in batch aqueous solutions. The FTIR spectrum revealed that (3-aminotrimethyl) phosphonic acid functional groups were successfully grafted onto natural zeolite. The TGA analysis showed that the APZ had higher thermal stability and fewer active sites compared to SPC. The optimum adsorption capacity (qe) of 49 mg g-1 and 44 mg g-1 uranium was achieved using 25 mg SPC and 100 mg APZ, respectively at pH 4, 25oC after 1 and 6 h equilibrating time. The data best fitted the pseudo second-order kinetic model and Freundlich isotherm model. The thermodynamic studies showed that adsorption occurred chemically and exothermically for both APZ and SPC. The overall selectivity order for APZ was; Na ˃ Mn ≥ U ˃ Ca ˃ Fe and for SPC was; Fe ˃ Mn ≥ Ca ˃ U˃ Na. The findings showed that phosphate- and amine-functionalised zeolite bind strongly to uranium compared to the unmodified natural zeolite and other conventional adsorbents such as activated carbon. Their selectivity for this element was commendable. With further improvements in the synthetic protocols e.g. by using microwave-based methods, it should be possible to obtain functionalised zeolite that has superior properties to SPC. / XL2017

Thesis (Master of Engineering in Chemical Engineering)--Cape Peninsula University of Technology, 2019. / A shortage of water has resulted in the need to enhance the quality of wastewater that is released into the environment. The advanced oxidation process (AOP) using heterogeneous catalysis is a promising treatment process for the management of wastewater containing recalcitrant pollutants as compared to conventional processes. As AOP is a reliable wastewater treatment process, it is expected to be a sustainable answer to the shortage of clean water. AOP using heterogeneous catalysis based on Co3O4 particles and PMS, in particular has been found to be a powerful procedure for the degradation and mineralization of recalcitrant organic contaminants. In addition, due to the growing application of Co3O4 in lithium batteries, large quantities of these particles will be recovered as waste from spent lithium batteries, so there is a need to find a use for them. Although this method has received some promising feedback, challenges still need to be addressed, such as the toxicity of cobalt particles, the poor chemical and thermal stability and particle aggregation, and the prompting of lower catalytic efficiency in long haul application. Furthermore, the removal of the catalyst after the treatment of pollutants is also an issue. In order to be applicable, a novel catalyst must be produced requiring the combination of Co3O4 with a support material in order to inhibit cobalt leaching and generate better particle stability. From the available literature, TiO2 was found to be the best support material because it not only provides a large surface area for well dispersed Co3O4, but it also forms strong Co-O-Ti bonds which greatly reduced cobalt leaching as compared to other support materials. Moreover, it also greatly encourages the formation of surface Co–OH complexes, which is considered a crucial step for PMS activation. Therefore, the issues cited above could be avoided by producing a Co3O4/TiO2 heterojunction catalyst.

Thesis (MTech (Chemistry))--Cape Peninsula University of Technology, 2017. / Pharmaceuticals have found extensive application in human health management. They are released into the environment through urine, excreta and inappropriate disposal methods. Residues of pharmaceutical products have been reported to show toxic consequences in some freshwater and marine organisms. Antibiotics are one of the most important groups of common human pharmaceuticals widely in use as prescribed and non-prescribed drugs. Antibiotics and their metabolites have been quantitated in water and found in trace levels. But even at such low concentrations they can maintain high biological activities with potential adverse effects on humans and animals. Unfortunately, many pharmaceutical compounds are resistant to breakdown in the environment, hence they have tendency for environmental magnification, since they are designed to be biologically active. Therefore, there is need to evaluate their environmental levels and their possible abatement methods using simple, cheap and low cost techniques, in order to avert their potential toxic consequences. In this research, a cost effective, robust, selective and rugged method for the analysis of antibiotics in water samples using liquid chromatography was developed, and used for monitoring levels of the selected antibiotics in Diep River. Also, an effective remediation procedure for these contaminants in water was developed using activated carbon produced from grape slurry waste.

by Chan Shuk Mei. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 138-149). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Abstracts --- p.ii / Contents --- p.vi / List of figures --- p.xi / List of plates --- p.xiv / List of tables --- p.xv / Abbreviations --- p.xvi / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Pentachlorophenol --- p.1 / Chapter 1.1.1 --- Characteristics of pentachlorophenol --- p.1 / Chapter 1.1.2 --- Application of pentachlorophenol --- p.4 / Chapter 1.1.3 --- The fate of pentachlorophenol in environment --- p.5 / Chapter 1.1.4 --- The toxicity of pentachlorophenol --- p.9 / Chapter 1.1.5 --- Remediation of pentachlorophenol --- p.13 / Chapter 1.1.5.1 --- Physical treatment / Chapter 1.1.5.2 --- Chemical treatment / Chapter 1.1.5.3 --- Biological treatment / Chapter 1.1.5.4 --- Alternative for combining two treatments / Chapter 1.2 --- Biosorbents --- p.18 / Chapter 1.2.1 --- Chitin and chitosan --- p.21 / Chapter 1.2.1.1 --- History of chitin and chitosan --- p.21 / Chapter 1.2.1.2 --- Structures of chitin and chitosan --- p.21 / Chapter 1.2.1.3 --- Sources of chitin and chitosan --- p.23 / Chapter 1.2.1.4 --- Application of chitin and chitosan --- p.26 / Chapter 1.2.1.5 --- Study on PCP removal by chitinous material --- p.28 / Chapter 1.2.2 --- Factors affecting biosorption --- p.29 / Chapter 1.2.2.1 --- Solution pH --- p.29 / Chapter 1.2.2.2 --- Concentration of biosorbent --- p.30 / Chapter 1.2.2.3 --- Retention time --- p.31 / Chapter 1.2.2.4 --- Temperature --- p.32 / Chapter 1.2.2.5 --- Agitation rate --- p.32 / Chapter 1.2.2.6 --- Initial sorbate concentration --- p.33 / Chapter 1.2.3 --- Modeling of biosorption --- p.33 / Chapter 1.2.3.1 --- Langmuir adsorption model --- p.34 / Chapter 1.2.3.2 --- Freundlich adsorption model --- p.34 / Chapter 1.3 --- Photocatalytic degradation --- p.35 / Chapter 1.3.1 --- Titanium dioxide --- p.36 / Chapter 1.3.2 --- Mechanism of photocatalytic oxidation using photocatalyst TiO2 --- p.36 / Chapter 1.3.3 --- Advantages of photocatalytic oxidation with Ti02 and H2O2 --- p.41 / Chapter 1.3.4 --- Degradation of PCP by photocatalytic oxidation --- p.41 / Chapter 2. --- Objectives --- p.45 / Chapter 3. --- Materials and methods --- p.46 / Chapter 3.1 --- Biosorbents --- p.46 / Chapter 3.1.1 --- Production of biosorbents --- p.46 / Chapter 3.1.2 --- Scanning electron microscope of biosorbents --- p.48 / Chapter 3.1.3 --- Pretreatment of biosorbents --- p.48 / Chapter 3.2 --- Pentachlorophenol preparation --- p.48 / Chapter 3.3 --- Batch biosorption experiment --- p.48 / Chapter 3.3.1 --- Quantification of pentachlorophenol by HPLC --- p.51 / Chapter 3.3.2 --- Data analysis for biosorption --- p.51 / Chapter 3.3.3 --- Selection of optimal conditions for batch PCP adsorption --- p.52 / Chapter 3.3.3.1 --- Effect of initial pH and biosorbent concentration --- p.52 / Chapter 3.3.3.2 --- Improvement on pH effect and biosorbent concentration --- p.52 / Chapter 3.3.3.3 --- Effect of temperature --- p.53 / Chapter 3.3.3.4 --- Effect of agitation rate --- p.53 / Chapter 3.3.4 --- Effect of initial PCP concentration and biosorbent concentration --- p.53 / Chapter 3.3.4.1 --- Adsorption isotherm --- p.54 / Chapter 3.4 --- Photocatalytic oxidation --- p.54 / Chapter 3.4.1 --- Reaction mixture solution --- p.54 / Chapter 3.4.2 --- Photocatalytic reactor --- p.55 / Chapter 3.4.3 --- Batch photocatalytic oxidation system --- p.55 / Chapter 3.4.4 --- Selection of extraction solvent --- p.59 / Chapter 3.4.5 --- Extraction efficiency --- p.59 / Chapter 3.4.6 --- Data analysis for PCO --- p.60 / Chapter 3.4.7 --- Irradiation time --- p.60 / Chapter 3.4.8 --- Determination of hydrogen peroxide concentration --- p.61 / Chapter 3.4.9 --- Effect of biosorbent concentration in PCO --- p.61 / Chapter 3.4.10 --- Effect of PCP amount on biosorbent in PCO --- p.61 / Chapter 3.4.11 --- Determination of chloride ion concentration and total organic carbon during PCO --- p.62 / Chapter 3.4.12 --- Identification the intermediates of PCP degradation by PCO --- p.62 / Chapter 3.4.13 --- Evaluation of the change of PCO treated biosorbents --- p.63 / Chapter 3.4.13.1 --- Chitin assay --- p.64 / Chapter 3.4.13.2 --- Diffuse reflectance Fourier transform infra-red spectroscopy --- p.64 / Chapter 3.4.13.3 --- Protein assay --- p.66 / Chapter 3.4.13.4 --- Biosorption efficiency --- p.66 / Chapter 3.4.14 --- Multiple biosorption and PCO cycles of PCP --- p.66 / Chapter 3.4.15 --- Evaluation for the toxicity change of PCP adsorbed biosorbents during PCO --- p.67 / Chapter 4. --- Results --- p.68 / Chapter 4.1 --- Batch biosorption experiment --- p.68 / Chapter 4.1.1 --- Selection of optimal conditions for batch PCP adsorption --- p.68 / Chapter 4.1.1.1 --- Effect of initial pH and biosorbent concentration --- p.68 / Chapter 4.1.1.2 --- Effect of Tris buffer and biosorbent concentrations --- p.73 / Chapter 4.1.1.3 --- Effect of temperature --- p.73 / Chapter 4.1.1.4 --- Effect of agitation rate --- p.73 / Chapter 4.1.2 --- Effect of initial PCP concentration and biosorbent concentration --- p.81 / Chapter 4.1.2.1 --- Adsorption isotherm --- p.82 / Chapter 4.2 --- Photocatalytic oxidation --- p.88 / Chapter 4.2.1 --- Selection of extraction solvent --- p.88 / Chapter 4.2.2 --- Determination of hydrogen peroxide concentration --- p.88 / Chapter 4.2.3 --- Effect of biosorbent concentration in PCO --- p.88 / Chapter 4.2.4 --- Effect of PCP amount on biosorbent in PCO --- p.94 / Chapter 4.2.5 --- Determination of chloride ion concentration and total organic carbon during PCO --- p.98 / Chapter 4.2.6 --- Identification the intermediates of PCP degradation by PCO --- p.102 / Chapter 4.2.7 --- Evaluation of the change of PCO treated biosorbents --- p.102 / Chapter 4.2.7.1 --- Chitin assay --- p.102 / Chapter 4.2.7.2 --- Diffuse reflectance Fourier transform infra-red spectroscopy --- p.102 / Chapter 4.2.7.3 --- Protein assay --- p.102 / Chapter 4.2.7.4 --- Biosorption efficiency --- p.109 / Chapter 4.2.8 --- Multiple biosorption and PCO cycles of PCP --- p.109 / Chapter 4.2.9 --- Evaluation for the toxicity change of PCP adsorbed biosorbents during PCO --- p.109 / Chapter 5. --- Discussion --- p.115 / Chapter 5.1 --- Batch biosorption experiment --- p.115 / Chapter 5.1.1 --- Selection of optimal conditions for batch PCP adsorption --- p.115 / Chapter 5.1.1.1 --- Effect of initial pH --- p.115 / Chapter 5.1.1.2 --- Effect of Tris buffer and biosorbent concentrations --- p.118 / Chapter 5.1.1.3 --- Retention time --- p.119 / Chapter 5.1.1.4 --- Effect of temperature --- p.120 / Chapter 5.1.1.5 --- Effect of agitation rate --- p.121 / Chapter 5.1.2 --- Effect of initial PCP concentration and biosorbent concentration --- p.121 / Chapter 5.1.2.1 --- Modeling of biosorption --- p.122 / Chapter 5.2 --- Photocatalytic oxidation --- p.123 / Chapter 5.2.1 --- Selection of extraction solvent --- p.124 / Chapter 5.2.2 --- Determination of hydrogen peroxide concentration --- p.124 / Chapter 5.2.3 --- Effect of biosorbent concentration in PCO --- p.125 / Chapter 5.2.4 --- Effect of PCP amount on biosorbent in PCO --- p.127 / Chapter 5.2.5 --- Determination of chloride ion concentration and total organic carbon during PCO --- p.127 / Chapter 5.2.6 --- Identification the intermediates of PCP degradation by PCO --- p.128 / Chapter 5.2.7 --- Evaluation of the change of PCO treated biosorbents --- p.128 / Chapter 5.2.7.1 --- Chitin assay --- p.129 / Chapter 5.2.7.2 --- Diffuse reflectance Fourier transform infra-red spectroscopy --- p.129 / Chapter 5.2.7.3 --- Protein assay --- p.131 / Chapter 5.2.7.4 --- Biosorption efficiency --- p.131 / Chapter 5.2.8 --- Multiple biosorption and PCO cycles of PCP --- p.132 / Chapter 5.2.9 --- Evaluation for the toxicity change of PCP adsorbed biosorbents during PCO --- p.132 / Chapter 6. --- Conclusion --- p.134 / Chapter 7. --- Recommendation --- p.137 / Chapter 8. --- References --- p.138

Wu Xiujuan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 88-93). / Abstracts in English and Chinese. / ABSTRACT (Chinese) / ABSTRACT / ACKNOWLEDGEMENT / TABLE OF CONTENTS / LIST OF TABLES / LIST OF FIGURES / Chapter CHAPTER ONE: --- INTRODUCTION / Chapter 1.1 --- General B ackground --- p.1 / Chapter 1.2 --- Chromium in Environment and its Analysis --- p.2 / Chapter 1.2.1 --- Source of Chromium and its Harmful Effects on Human --- p.2 / Chapter 1.2.2 --- Methods for Separation and Determination of Chromium Species --- p.4 / Chapter 1.3 --- Arsenic in the Environment and its Toxicity --- p.4 / Chapter 1.4 --- Properties of TiO2 and Its Applications --- p.6 / Chapter 1.4.1 --- Photocatalytic Property of TiO2 --- p.6 / Chapter 1.4.2 --- Surface Acid-Basic Property of TiO2 --- p.8 / Chapter 1.5 --- Adsorption --- p.11 / Chapter 1.6 --- Fundamental of ICP-AES and ICP-MS --- p.12 / Chapter 1.6.l --- Principle of ICP-AES --- p.12 / Chapter 1.6.2 --- Principle of ICP-MS --- p.14 / Chapter 1.7 --- Scope of Work --- p.18 / Chapter CHAPTER TWO: --- SEPERATION OF CHROMIUM SPECIES ON TIO2 / Chapter 2.1 --- Introduction --- p.19 / Chapter 2.2 --- Experimental --- p.23 / Chapter 2.2.1 --- Materials --- p.23 / Chapter 2.2.2 --- Instruments --- p.24 / Chapter 2.2.2.1 --- Coupling of TiO2 column and ICP-AES --- p.24 / Chapter 2.2.2.2 --- Coupling of TiO2 column and ICP-MS --- p.26 / Chapter 2.2.3. --- Procedure --- p.29 / Chapter 2.3 --- Results and Discussion --- p.33 / Chapter 2.3.1 --- Preliminary study on the adsorption of Cr(III) and Cr(VI) on TiO2 --- p.33 / Chapter 2.3.2 --- Development and Verification of the proposed method for speciation of Cr(III) and Cr(VI) in aqueous solution --- p.42 / Chapter 2.3.3 --- Practical application of the proposed method for separation and determination of Cr(III) and Cr(VI) --- p.46 / Chapter CHAPTER THREE: --- ADSORPTION OF ARSENIC SPECIES ON TiO2 / Chapter 3.1 --- Introduction --- p.61 / Chapter 3.2 --- Experimental --- p.66 / Chapter 3.2.1 --- Materials --- p.66 / Chapter 3.2.2 --- Instruments --- p.69 / Chapter 3.2.3 --- Procedure --- p.70 / Chapter 3.3 --- Results and Discussion --- p.71 / Chapter 3.3.1 --- Adsorption Kinetics --- p.71 / Chapter 3.3.2 --- Effect of pH on Adsorption of Arsenic Species --- p.71 / Chapter 3.3.3 --- Adsorption Isotherm --- p.74 / Chapter 3.3.4 --- Adsorption Model --- p.76 / Chapter 3.3.5 --- Factors Affecting the Adsorption of Arsenic Species on p25 and Rutile TiO2 --- p.83 / Chapter CHAPTER FOUR: --- CONCLUSION --- p.86 / REFERENCES --- p.88

Biological nitrogen removal (BNR) has been applied for more than a century in the interests of preserving and enhancing public health and the environment. But only during the last few decades has the development of molecular techniques using biomolecules such as nucleic acids (DNA and RNA) and proteins allowed the accurate description and characterization of the phylogenetic and functional diversity of microbial communities. Moreover, thanks to recent advances in genomics and next-generation sequencing technologies, microbial community analyses have initiated a new era of microbial ecology. Notwithstanding the fact that the efficiency and robustness of a wastewater treatment mainly depend on the composition and activity of BNR communities, research on the structural and functional microbial ecology of the engineered BNR process remains rare with respect to next-generation sequencing and bioinformatics. This dissertation aims to bridge high-priority knowledge gaps in determining and applying knowledge of microbial structure (who is there and how many?) and function (what are they doing? what else can they do?) to the practice of BNR processes, and to opening up the ‘black-box’ of energy and resource efficient engineered BNR processes using a systems biology approach. Specific objectives were to (1) selectively enrich Nitrospira spp. from a mixed environmental microbial consortium (such as activated sludge) in a continuously operated bioreactor and characterize the microbial ecology during the course of enrichment, determine key kinetic parameters of enriched Nitrospira spp., (2) examine the inhibitory effects of nitrogenous intermediates (such as hydroxylamine, presented herein) on the physiological and molecular responses of Nitrospira spp. in terms of both catabolism and anabolism, (3) characterize bacterial community composition and their dynamics by 16S rRNA gene amplicon sequencing under varying reactor operational conditions from full-scale WWTPs and identify process parameters that most significantly correlate with those dynamics, (4) interpret metagenomic (DNA-based) and metatranscriptomic (RNA-based) derived structure, metabolic function and activity of the full-scale BNR microbial communities, and (5) describe gene expression in the same full-scale BNR communities in response to alternating anoxic-aerobic conditions using a metatranscriptomic approach. First, planktonic Nitrospira spp. were successfully enriched from activated sludge in a sequencing batch reactor by maintaining sustained limiting extant nitrite and dissolved oxygen concentrations for a half year. The determined parameters collectively reflected not just higher affinities of this enrichment for nitrite and oxygen, respectively, but also a higher biomass yield and energy transfer efficiency relative to other NOB such as Nitrobacter spp. Used in combination, these kinetic and thermodynamic parameters can help toward the development and application of energy-efficient biological nutrient removal processes through effective Nitrospira out-selection. Second, using quantitative activity measurements (respirometrc rates) with functional gene expression profiles, this study demonstrated that N-intermediates such as hydroxylamine (NH¬2OH) can strongly inhibit the activity and expression of key anabolic (energy synthesis) and catabolic (biomass synthesis) pathways of Nitrospira spp. A strategy that relies upon the transient accumulation and consumption of such intermediates (such as transient aeration) could provide the platform for successful suppression of Nitrospira spp. in the next generation of energy efficient engineered BNR processes. Third, 16S rRNA gene amplicon sequencing revealed that microbial community structure and their dynamics significantly varied depending on seven differing wastewater treatment processes. The findings showed that five process parameters of wastewater influenced the dynamics of BNR communities; water temperature was correlated most strongly to the variance of bacterial communities, followed by effluent NH3, effluent NO3-, removed N, and effluent NO2-. The results provided insights into the underlying ecological pattern of community compositions and dynamics in full-scale WWTPs; and correlation with process parameters brought about distinct communities that enable different microbial activities. However, one of the greatest challenges was to elucidate the relationship between microbial structure and their “active” functions, which are related to reactor performance (This challenge continued into fourth study chapter summarized below). Fourth, continuing from the previous study, combined metagenomics and metatranscriptomics revealed far superior richness of information of not just microbial structure, but also potential (through metagenomics) and expressed function (through metatranscriptimics) within the complex activated sludge processes. Via independent analysis of whole-DNA and whole-RNA, the entire microbial community and its in situ active members, involved in nitrificaiton and denitrification, were compared. Active nitrifiers and denitrifiers obtained by RNA analysis exhibited relatively high abundances in DNA-derived communities. Further gene expression annotation on nitrogen removal revealed that the expressions of denitrification-related genes except nos were increased under anoxic conditions relative to aerobic conditions, while the expressions of nitrifying genes were decreased. Our findings led to an improved understanding of metabolic activities and roles of BNR microbial communities, and offer the first metatranscriptional insights on engineered nutrient removal in anoxic conditions relative to aerobic conditions in full-scale wastewater systems. In sum, next-generation sequencing as well as traditional molecular techniques shed light on microbial diversity and different functional genes in varying engineered BNR systems. Furthermore, this dissertation provides a wealth of knowledge on systematic explorations of the linkage between structure and function of BNR communities, and offers engineering applications to BNR processes including energy and resource efficient engineered systems. It is expected that the implementation and further expansion of this work will improve the design and operation of engineered BNR processes, eventually producing benefits for the global population and the environment.

by Cheung Kit Hing. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 175-199). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Abstracts --- p.ii / Table of Contents --- p.vi / List of Figures --- p.xviii / List of Plates --- p.xxii / List of Tables --- p.xxiii / Abbreviations --- p.xxv / Equations --- p.xxviii / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- The chemistry of azo dyes --- p.1 / Chapter 1.2 --- Azo dyes classification --- p.2 / Chapter 1.3 --- Environmental concerns and toxicity --- p.4 / Chapter 1.3.1 --- Toxicity of azo dyes --- p.5 / Chapter 1.3.2 --- Carcinogenicity --- p.5 / Chapter 1.3.3 --- Ecotoxicity --- p.11 / Chapter 1.3.3.1 --- Toxicity to microorganisms --- p.12 / Chapter 1.3.3.2 --- Toxicity towards vertebrates --- p.13 / Chapter 1.4 --- Treatment of azo dyes --- p.13 / Chapter 1.4.1 --- Physical treatment --- p.14 / Chapter 1.4.1.1 --- Adsorption --- p.14 / Chapter 1.4.1.2 --- Membrane technology --- p.15 / Chapter 1.4.2 --- Chemical treatments --- p.15 / Chapter 1.4.2.1 --- Chlorination --- p.16 / Chapter 1.4.2.2 --- Fenton's reaction --- p.16 / Chapter 1.4.2.3 --- Ozonation --- p.16 / Chapter 1.4.2.4 --- Coagulation --- p.17 / Chapter 1.4.3 --- Biological treatments --- p.17 / Chapter 1.4.3.1 --- Activated sludge process --- p.18 / Chapter 1.4.3.2 --- Biodegradation --- p.18 / Chapter 1.4.3.3 --- Biosorption --- p.21 / Chapter 1.4.3.3.1 --- Modeling of sorption --- p.24 / Chapter 1.4.3.3.1.1 --- Langmuir sorption model --- p.24 / Chapter 1.4.3.3.1.2 --- Freundlich sorption model --- p.25 / Chapter 1.4.4 --- Advanced oxidation processes --- p.25 / Chapter 1.4.4.1 --- Photocatalytic oxidation --- p.26 / Chapter 1.4.4.2 --- Titanium dioxide (TiO2) --- p.26 / Chapter 1.4.4.3 --- Mechanism of photocatalytic oxidation using photocatalyst TiO2 --- p.28 / Chapter 1.4.4.4 --- Photocatalytic oxidation of s-triazine containing compounds --- p.30 / Chapter 1.4.4.5 --- Photocatalytic oxidation of Procion Red MX-5B --- p.31 / Chapter 1.4.4.6 --- Cyanuric acid --- p.32 / Chapter 1.4.4.6.1 --- Application --- p.32 / Chapter 1.4.4.6.2 --- Toxicity --- p.32 / Chapter 1.4.4.6.3 --- Photocatalytic oxidation resistance --- p.34 / Chapter 1.4.4.6.4 --- Biodegradation --- p.35 / Chapter 1.4.4.7 --- Enhancement of photocatalytic oxidation by using sorbent immobilized with TiO2 --- p.35 / Chapter 1.4.4.7.1 --- Sorption --- p.35 / Chapter 1.4.4.7.2 --- Immobilization of TiO2 --- p.37 / Chapter 1.4.8 --- Integration of treatment methods --- p.39 / Chapter 2. --- Objectives --- p.41 / Chapter 3. --- Materials and methods --- p.42 / Chapter 3.1. --- Sorption --- p.42 / Chapter 3.1.1 --- Chemical reagents --- p.42 / Chapter 3.1.2 --- Determination of Procion Red MX-5B --- p.42 / Chapter 3.1.3 --- Sampling --- p.44 / Chapter 3.1.4 --- Isolation of Procion Red MX-5B-sorbing bacteria --- p.44 / Chapter 3.1.5 --- Screening of Procion Red MX-5B sorption ability --- p.44 / Chapter 3.1.6 --- Identification of isolated bacterium --- p.46 / Chapter 3.1.7 --- Optimization of cell yield and sorption capacity --- p.47 / Chapter 3.1.7.1 --- Preparation of cell culture of Vibrio sp. --- p.47 / Chapter 3.1.7.2 --- Growth phase --- p.47 / Chapter 3.1.7.2.1 --- Growth curve --- p.47 / Chapter 3.1.7.2.2 --- Dye sorption capacity --- p.47 / Chapter 3.1.7.3 --- Initial pH --- p.48 / Chapter 3.1.7.3.1 --- Growth curve --- p.48 / Chapter 3.1.7.3.2 --- Dye sorption capacity --- p.48 / Chapter 3.1.7.4 --- Temperature --- p.49 / Chapter 3.1.7.4.1 --- Growth curve --- p.49 / Chapter 3.1.7.4.2 --- Dye sorption capacity --- p.49 / Chapter 3.1.7.5 --- Glucose concentrations --- p.49 / Chapter 3.1.7.5.1 --- Growth curve --- p.49 / Chapter 3.1.7.5.2 --- Dye sorption capacity --- p.50 / Chapter 3.1.8 --- Optimization of sorption process --- p.50 / Chapter 3.1.8.1 --- Preparation of sorbent --- p.50 / Chapter 3.1.8.2 --- Dry weight of sorbent --- p.50 / Chapter 3.1.8.3 --- Temperature --- p.50 / Chapter 3.1.8.4 --- Agitation rate --- p.50 / Chapter 3.1.8.5 --- Salinity --- p.51 / Chapter 3.1.8.6 --- Initial pH --- p.51 / Chapter 3.1.8.7 --- Concentration of Procion Red MX-5B --- p.51 / Chapter 3.1.8.8 --- Combination study of salinity and initial pH --- p.51 / Chapter 3.2. --- Photocatalytic oxidation reaction --- p.52 / Chapter 3.2.1 --- Chemical reagents --- p.52 / Chapter 3.2.2 --- Photocatalytic reactor --- p.52 / Chapter 3.2.3 --- Optimization of sorption and photocatalytic oxidation reactions using biomass of Vibrio sp.immobilized in calcium alginate beads --- p.54 / Chapter 3.2.3.1 --- Effect of dry weight of immobilized cells of Vibrio sp. --- p.54 / Chapter 3.2.3.1.1 --- Sorption --- p.55 / Chapter 3.2.3.1.2 --- Photocatalytic oxidation --- p.56 / Chapter 3.2.3.2 --- Effect of UV intensities --- p.57 / Chapter 3.2.3.3 --- Effect of TiO2 concentrations --- p.57 / Chapter 3.2.3.3.1 --- Sorption --- p.57 / Chapter 3.2.3.3.2 --- Photocatalytic oxidation --- p.57 / Chapter 3.2.3.4 --- Effect of H202 concentrations --- p.57 / Chapter 3.2.3.5 --- Effect of the number of beads --- p.58 / Chapter 3.2.3.5.1 --- Sorption --- p.58 / Chapter 3.2.3.5.2 --- Photocatalytic oxidation --- p.58 / Chapter 3.2.3.6 --- Effect of initial pH with and without the addition of H2O2 --- p.58 / Chapter 3.2.3.7 --- Control experiments for photocatalytic oxidation of Procion Red MX-5B --- p.59 / Chapter 3.2.3.8 --- Combinational study of UV intensities and H2O2 concentrations --- p.59 / Chapter 3.2.3.9 --- Photocatalytic oxidation of Procion Red MX-5B under optimal conditions --- p.59 / Chapter 3.2.3.10 --- "Sorption isotherms of calcium alginate beads immobilized with 70 mg Vibrio sp. and 5,000 mg/L TiO2" --- p.59 / Chapter 3.3 --- Biodegradation --- p.60 / Chapter 3.3.1 --- Chemical reagents --- p.60 / Chapter 3.3.2 --- Sampling --- p.60 / Chapter 3.3.3 --- Enrichment --- p.60 / Chapter 3.3.4 --- Isolation of cyanuric acid-utilizing bacteria --- p.61 / Chapter 3.3.5 --- Determination of cyanuric acid --- p.61 / Chapter 3.3.6 --- Screening of Procion Red MX-5B sorption ability --- p.61 / Chapter 3.3.7 --- Screening of cyanuric acid-utilizing ability --- p.61 / Chapter 3.3.8 --- Bacterial identification --- p.63 / Chapter 3.3.9 --- Growth and cyanuric acid removal efficiency of the selected bacterium --- p.63 / Chapter 3.3.10 --- Optimization of reaction conditions --- p.64 / Chapter 3.3.10.1 --- Effect of salinity --- p.64 / Chapter 3.3.10.2 --- Effect of cyanuric acid concentrations --- p.65 / Chapter 3.3.10.3 --- Effect of temperature --- p.65 / Chapter 3.3.10.4 --- Effect of agitation rate --- p.65 / Chapter 3.3.10.5 --- Effect of initial pH --- p.66 / Chapter 3.3.10.6 --- Effect of initial glucose concentration --- p.66 / Chapter 3.3.10.7 --- Combinational study of glucose and cyanuric acid concentrations --- p.66 / Chapter 3.4 --- Detection of cyanuric acid formed in photocatalytic oxidation reaction --- p.66 / Chapter 3.5 --- "Integration of sorption, photocatalytic oxidation and biodegradation" --- p.67 / Chapter 4. --- Results --- p.68 / Chapter 4.1. --- Sorption --- p.68 / Chapter 4.1.1 --- Determination of Procion Red MX-5B --- p.68 / Chapter 4.1.2 --- Isolation of Procion Red MX-5B-sorbing bacteria --- p.68 / Chapter 4.1.3 --- Screening of Procion Red MX-5B sorption ability --- p.68 / Chapter 4.1.4 --- Identification of isolated bacterium --- p.72 / Chapter 4.1.5 --- Optimization of cell yield and sorption capacity --- p.72 / Chapter 4.1.5.1 --- Growth phase --- p.72 / Chapter 4.1.5.1.1 --- Growth curve --- p.72 / Chapter 4.1.5.1.2 --- Dye sorption capacity --- p.72 / Chapter 4.1.5.2 --- Initial pH --- p.75 / Chapter 4.1.5.2.1 --- Growth curve --- p.75 / Chapter 4.1.5.2.2 --- Dye sorption capacity --- p.75 / Chapter 4.1.5.3 --- Temperature --- p.75 / Chapter 4.1.5.3.1 --- Growth curve --- p.75 / Chapter 4.1.5.3.2 --- Dye sorption capacity --- p.79 / Chapter 4.1.5.4 --- Glucose concentrations --- p.79 / Chapter 4.1.5.4.1 --- Growth curve --- p.79 / Chapter 4.1.5.4.2 --- Dye sorption capacity --- p.79 / Chapter 4.1.6 --- Optimization of sorption process --- p.82 / Chapter 4.1.6.1 --- Dry weight of sorbent --- p.82 / Chapter 4.1.6.2 --- Temperature --- p.82 / Chapter 4.1.6.3 --- Agitation rate --- p.86 / Chapter 4.1.6.4 --- Salinity --- p.86 / Chapter 4.1.6.5 --- Initial pH --- p.86 / Chapter 4.1.6.6 --- Concentration of Procion Red MX-5B --- p.90 / Chapter 4.1.6.7 --- Combination study of salinity and initial pH --- p.90 / Chapter 4.2. --- Photocatalytic oxidation reaction --- p.94 / Chapter 4.2.1 --- Effect of dry weight of immobilized cells of Vibrio sp. --- p.94 / Chapter 4.2.1.1 --- Sorption --- p.94 / Chapter 4.2.1.2 --- Photocatalytic oxidation --- p.96 / Chapter 4.2.2 --- Effect of UV intensities --- p.96 / Chapter 4.2.3 --- Effect of TiO2 concentrations --- p.96 / Chapter 4.2.3.1 --- Sorption --- p.96 / Chapter 4.2.3.2 --- Photocatalytic oxidation --- p.101 / Chapter 4.2.4 --- Effect of H2O2 concentrations --- p.101 / Chapter 4.2.5 --- Effect of the number of beads --- p.101 / Chapter 4.2.5.1 --- Sorption --- p.105 / Chapter 4.2.5.2 --- Photocatalytic oxidation --- p.105 / Chapter 4.2.6 --- Effect of initial pH with and without the addition of --- p.105 / Chapter 4.2.7 --- Control experiments for photocatalytic oxidation of Procion Red MX-5B --- p.109 / Chapter 4.2.8 --- Combinational study of UV intensities and H202 concentrations --- p.112 / Chapter 4.2.9 --- Photocatalytic oxidation of Procion Red MX-5B under optimal conditions --- p.112 / Chapter 4.2.10 --- "Sorption isotherms of calcium alginate beads immobilized with 70 mg Vibrio sp. and 5,000 mg/L Ti02" --- p.112 / Chapter 4.3 --- Biodegradation --- p.116 / Chapter 4.3.1 --- Isolation of cyanuric acid-utilizing bacteria --- p.116 / Chapter 4.3.2 --- Determination of cyanuric acid --- p.116 / Chapter 4.3.3 --- Screening of Procion Red MX-5B sorption ability --- p.116 / Chapter 4.3.4 --- Screening of cyanuric acid-utilizing ability --- p.116 / Chapter 4.3.5 --- Bacterial identification --- p.118 / Chapter 4.3.6 --- Growth and cyanuric acid removal efficiency of the selected bacterium --- p.118 / Chapter 4.3.7 --- Optimization of reaction conditions --- p.122 / Chapter 4.3.7.1 --- Effect of salinity --- p.122 / Chapter 4.3.7.2 --- Effect of cyanuric acid concentrations --- p.122 / Chapter 4.3.7.3 --- Effect of temperature --- p.126 / Chapter 4.3.7.4 --- Effect of agitation rate --- p.126 / Chapter 4.3.7.5 --- Effect of initial pH --- p.132 / Chapter 4.3.7.6 --- Effect of initial glucose concentration --- p.132 / Chapter 4.3.7.7 --- Combinational study of glucose and cyanuric acid concentrations --- p.132 / Chapter 4.4 --- Detection of cyanuric acid formed in photocatalytic oxidation reaction --- p.137 / Chapter 4.5 --- "Integration of sorption, photocatalytic oxidation and biodegradation" --- p.137 / Chapter 5. --- Discussion --- p.141 / Chapter 5.1 --- Sorption --- p.141 / Chapter 5.1.1 --- Isolation of Procion Red MX-5B-sorbing bacteria --- p.141 / Chapter 5.1.2 --- Screening of Procion Red MX-5B sorption ability --- p.141 / Chapter 5.1.3 --- Identification of isolated bacterium --- p.141 / Chapter 5.1.4 --- Optimization of cell yield and sorption capacity --- p.142 / Chapter 5.1.4.1 --- Growth phase --- p.142 / Chapter 5.1.4.1.1 --- Growth curve --- p.142 / Chapter 5.1.4.1.2 --- Dye sorption capacity --- p.143 / Chapter 5.1.4.2 --- Initial pH --- p.146 / Chapter 5.1.4.2.1 --- Growth curve --- p.146 / Chapter 5.1.4.2.2 --- Dye sorption capacity --- p.146 / Chapter 5.1.4.3 --- Temperature --- p.146 / Chapter 5.1.4.3.1 --- Growth curve --- p.146 / Chapter 5.1.4.3.2 --- Dye sorption capacity --- p.147 / Chapter 5.1.4.4 --- Glucose concentrations --- p.147 / Chapter 5.1.4.4.1 --- Growth curve --- p.147 / Chapter 5.1.4.4.2 --- Dye sorption capacity --- p.147 / Chapter 5.1.5 --- Optimization of sorption process --- p.148 / Chapter 5.1.5.1 --- Dry weight of sorbent --- p.148 / Chapter 5.1.5.2 --- Temperature --- p.148 / Chapter 5.1.5.3 --- Agitation rate --- p.149 / Chapter 5.1.5.4 --- Salinity --- p.149 / Chapter 5.1.5.5 --- Initial pH --- p.150 / Chapter 5.1.5.6 --- Concentration of Procion Red MX-5B (MX-5B) --- p.152 / Chapter 5.1.5.7 --- Combination study of salinity and initial pH --- p.153 / Chapter 5.2. --- Photocatalytic oxidation reaction --- p.153 / Chapter 5.2.1 --- Effect of immobilized cells of Vibrio sp. --- p.153 / Chapter 5.2.1.1 --- Sorption --- p.153 / Chapter 5.2.1.2 --- Photocatalytic oxidation --- p.154 / Chapter 5.2.2 --- Effect of UV intensities --- p.155 / Chapter 5.2.3 --- Effect of TiO2 concentrations --- p.155 / Chapter 5.2.3.1 --- Sorption --- p.155 / Chapter 5.2.3.2 --- Photocatalytic oxidation --- p.156 / Chapter 5.2.4 --- Effect of H2O2 concentrations --- p.156 / Chapter 5.2.5 --- Effect of the number of beads --- p.157 / Chapter 5.2.5.1 --- Sorption --- p.157 / Chapter 5.2.5.2 --- Photocatalytic oxidation --- p.158 / Chapter 5.2.6 --- Effect of initial pH with and without the addition of --- p.158 / Chapter 5.2.7 --- Control experiments for photocatalytic oxidation of Procion Red MX-5B --- p.160 / Chapter 5.2.8 --- Combinational study of UV intensities and H202 concentrations --- p.161 / Chapter 5.2.9 --- Photocatalytic oxidation of Procion Red MX-5B under optimal conditions --- p.161 / Chapter 5.2.10 --- "Sorption isotherms of calcium alginate beads immobilized with 70 mg Vibrio sp. and 5,000 mg/L Ti02" --- p.161 / Chapter 5.3 --- Biodegradation --- p.162 / Chapter 5.3.1 --- Isolation of cyanuric acid-utilizing bacteria --- p.162 / Chapter 5.3.2 --- Determination of cyanuric acid --- p.163 / Chapter 5.3.3 --- Screening of Procion Red MX-5B sorption ability --- p.163 / Chapter 5.3.4 --- Screening of cyanuric acid-utilizing ability --- p.163 / Chapter 5.3.5 --- Bacterial identification --- p.163 / Chapter 5.3.6 --- Growth and cyanuric acid removal efficiency of the selected bacterium --- p.164 / Chapter 5.3.7 --- Optimization of reaction conditions --- p.165 / Chapter 5.3.7.1 --- Effect of salinity --- p.165 / Chapter 5.3.7.2 --- Effect of cyanuric acid concentration --- p.165 / Chapter 5.3.7.3 --- Effect of temperature --- p.166 / Chapter 5.3.7.4 --- Effect of agitation rate --- p.167 / Chapter 5.3.7.5 --- Effect of initial pH --- p.167 / Chapter 5.3.7.6 --- Effect of initial glucose concentration --- p.167 / Chapter 5.3.7.7 --- Combinational study of glucose and cyanuric acid concentrations --- p.168 / Chapter 5.4 --- Detection of cyanuric acid formed in photocatalytic oxidation reaction --- p.170 / Chapter 5.5 --- "Integration of sorption, photocatalytic oxidation and biodegradation" --- p.171 / Chapter 5.6 --- Recommendations --- p.171 / Chapter 6. --- Conclusions --- p.173 / Chapter 7. --- References --- p.175 / Appendix --- p.200