Batch tests were performed to evaluate the relative performance of four B.C. coals (Hat Creek Oxidised, Kaiser-stock pile refuse, Kaiser-special plant feed and Cominco Ash) in removing heavy metals copper, lead, zinc and mercury from filtered primary sewage treatment plant effluent. Emphasis was placed on metal concentrations of 10 mg/l and less. Hat Creek coal was found to be much superior to the other three and its efficiency is comparable to that of Darco activated carbon 12 x 20. Hat Creek and Kaiser-stock pile refuse coals were further used in column tests to evaluate the relative performance of these coals in removing copper, lead and zinc under dynamic conditions. Again emphasis was placed on influent metal concentrations of 10 mg/1 and less and once more the performance of Hat Creek coal was much superior to that of Kaiser coal. Tests with activated carbon indicate Hat Creek coal to be a close competitor for use in advanced waste treatment for heavy metal removal. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

by Li Ka Ling. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 221-242). / Text in English; abstracts in English and Chinese. / by Li Ka Ling. / Acknowledgements --- p.i / Abstract --- p.ii / Contents --- p.vi / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Literature review --- p.1 / Chapter 1.1.1 --- Heavy metals in our environment --- p.1 / Chapter 1.1.2 --- Major source of metal pollution in Hong Kong --- p.2 / Chapter 1.1.3 --- Chemistry and toxicity of copper ion --- p.9 / Chapter 1.1.4 --- Removal of metal ions from effluents by precipitation --- p.12 / Chapter 1.1.4.1 --- Metal ions in solution --- p.12 / Chapter 1.1.4.2 --- Precipitation of metal ions --- p.13 / Chapter 1.1.4.3 --- pH adjustment reagents --- p.15 / Chapter 1.1.4.4 --- Precipitation of complexed metal ions --- p.19 / Chapter 1.1.5 --- Other physico-chemical methods for the removal of metal ions --- p.21 / Chapter 1.1.6 --- Removal of metal ions by microorganisms --- p.24 / Chapter 1.1.6.1 --- Biosorption --- p.24 / Chapter 1.1.6.2 --- Other mechanisms for the accumulation of metal ions --- p.28 / Chapter 1.1.6.3 --- An attractive alternative for the removal and recovery of metal ions:biosorption --- p.30 / Chapter 1.1.7 --- Factors affecting biosorption --- p.37 / Chapter 1.1.7.1 --- Culture conditions --- p.38 / Chapter 1.1.7.2 --- pH of solution --- p.39 / Chapter 1.1.7.3 --- Concentration of biosorbent --- p.41 / Chapter 1.1.7.4 --- Initial metal ion concentration --- p.42 / Chapter 1.1.7.5 --- Presence of other cations --- p.43 / Chapter 1.1.7.6 --- Presence of anions --- p.45 / Chapter 1.1.8 --- Properties and uses of magnetite --- p.46 / Chapter 1.1.8.1 --- Physical and chemical properties of magnetite --- p.46 / Chapter 1.1.8.2 --- Use of magnetite for wastewater treatment --- p.48 / Chapter 1.1.8.3 --- Immobilization of cells on magnetite for metal ion removal --- p.49 / Chapter 1.2 --- Objectives of the present study --- p.54 / Chapter 2. --- Materials and methods --- p.57 / Chapter 2.1 --- Effects of physico-chemical factors on the precipitation of Cu2+ --- p.57 / Chapter 2.1.1 --- Reagents and chemicals --- p.57 / Chapter 2.1.2 --- Effects of equilibrium time --- p.59 / Chapter 2.1.3 --- Effects of pH --- p.60 / Chapter 2.1.4 --- Presence of anions and other cations --- p.61 / Chapter 2.1.5 --- "Presence of chelating agent, EDTA" --- p.61 / Chapter 2.2 --- Dissolution of metal sludge --- p.63 / Chapter 2.2.1 --- Dewatering and drying of metal sludge --- p.63 / Chapter 2.2.2 --- Dissolving of metal sludge by sulfuric acid --- p.63 / Chapter 2.3 --- Culture of biomass --- p.65 / Chapter 2.3.1 --- Subculturing of the biomass --- p.65 / Chapter 2.3.2 --- Culture media --- p.66 / Chapter 2.3.3 --- Growth and preparation of the cell suspension --- p.66 / Chapter 2.4 --- Immobilization of the bacterial cells on magnetites --- p.66 / Chapter 2.5 --- Metal ion removal studies --- p.71 / Chapter 2.5.1 --- Preparation of concentrated Cu2+ solutions --- p.71 / Chapter 2.5.2 --- Removal of Cu2+ in the concentrated Cu2+ solutions by magnetite- immobilized cells --- p.74 / Chapter 2.5.3 --- Effects of EDTA --- p.76 / Chapter 2.5.4 --- Effects of anions --- p.77 / Chapter 2.5.5 --- Effects of other cations --- p.78 / Chapter 2.6 --- Maximum removal efficiency of Cu2+ by magnetite-immobilized cells --- p.79 / Chapter 2.7 --- Recovery of adsorbed Cu2+ from magnetite-immobilized cell --- p.79 / Chapter 2.7.1 --- Desorption of Cu2+ from the immobilized cells using sulfuric acid --- p.79 / Chapter 2.7.2 --- Multiple adsorption-desorption cycles --- p.80 / Chapter 2.8 --- Treatment of electroplating effluent by magnetite-immobilized cells --- p.80 / Chapter 2.8.1 --- Removal and recovery of Cu2+ from electroplating effluent collected from rinsing baths --- p.80 / Chapter 2.8.2 --- Removal and recovery of Cu2+ from electroplating effluent collected from final collecting tank --- p.83 / Chapter 2.9 --- Data analysis --- p.84 / Chapter 3. --- Results --- p.86 / Chapter 3.1 --- Effects of physical-chemical factors on the precipitation of Cu2+ --- p.86 / Chapter 3.1.1 --- Effects of equilibrium time --- p.86 / Chapter 3.1.2 --- Effects of pH --- p.86 / Chapter 3.1.3 --- Presence of anions --- p.89 / Chapter 3.1.3.1 --- Cu2+-S042- systems --- p.89 / Chapter 3.1.3.2 --- Cu2+-Cl- systems --- p.89 / Chapter 3.1.3.3 --- Cu2+-Cr2072- systems --- p.89 / Chapter 3.1.3.4 --- Cu2+-mixed anions systems --- p.93 / Chapter 3.1.4 --- Presence of other cations --- p.93 / Chapter 3.1.4.1 --- Cu2+-Ni2+ systems --- p.93 / Chapter 3.1.4.2 --- Cu2+-Zn2+ systems --- p.96 / Chapter 3.1.4.3 --- Cu2+-Cr6+ systems --- p.96 / Chapter 3.1.4.4 --- Cu2+-mixed cations systems --- p.99 / Chapter 3.1.5 --- "Presence of chelating agent, EDTA" --- p.99 / Chapter 3.1.5.1 --- Cu2+-EDTA4 -mixed anions systems --- p.102 / Chapter 3.1.5.2 --- Cu2+-EDTA4--mixed cations systems --- p.102 / Chapter 3.2 --- Dissolution of metal sludge --- p.105 / Chapter 3.2.1 --- Dewatering and drying of metal sludge --- p.105 / Chapter 3.2.2 --- Dissolving of metal sludge by sulfuric acid --- p.105 / Chapter 3.3 --- Removal of Cu2+ in the concentrated Cu2+ solution by magnetite- immobilized cells --- p.109 / Chapter 3.4 --- Effects of EDTA on removal and recovery of Cu2+ by magnetite- immobilized cells --- p.109 / Chapter 3.4.1 --- Effects of EDTA --- p.109 / Chapter 3.4.2 --- Effects of EDTA after precipitation --- p.112 / Chapter 3.5 --- Effects of anions on removal and recovery of Cu2+ by magnetite- immobilized cells --- p.120 / Chapter 3.5.1 --- Effects of anions --- p.120 / Chapter 3.5.2 --- Effects of anions after precipitation --- p.120 / Chapter 3.5.3 --- Effects of anions in the presence of EDTA after precipitation --- p.124 / Chapter 3.6 --- Effects of other cations on removal and recovery of Cu2+ by magnetite-immobilized cells --- p.129 / Chapter 3.6.1 --- Effects of other cations --- p.129 / Chapter 3.6.2 --- Effects of other cations after precipitation --- p.137 / Chapter 3.6.3 --- Effects of other cations in the presence of EDTA after precipitation --- p.137 / Chapter 3.7 --- Maximum removal efficiency of Cu2+ by magnetite-immobilized cells --- p.142 / Chapter 3.8 --- Multiple adsorption-desorption cycle --- p.148 / Chapter 3.9 --- Treatment of electroplating effluent by magnetite-immobilized cells --- p.148 / Chapter 3.9.1 --- Removal and recovery of Cu2+ from electroplating effluent collected from rinsing baths --- p.148 / Chapter 3.9.2 --- Removal and recovery of Cu2+ from electroplating effluent collected from final collecting tank --- p.158 / Chapter 4. --- Discussion --- p.167 / Chapter 4.1 --- Effects of physical-chemical factors on the precipitation of Cu2+ --- p.167 / Chapter 4.1.1 --- Effects of equilibrium time --- p.167 / Chapter 4.1.2 --- Effects of pH --- p.168 / Chapter 4.1.3 --- Presence of anions --- p.169 / Chapter 4.1.4 --- Presence of other cations --- p.170 / Chapter 4.1.5 --- "Presence of chelating agent, EDTA" --- p.171 / Chapter 4.1.5.1 --- Presence of EDTA with anions --- p.174 / Chapter 4.1.5.2 --- Presence of EDTA with other cations --- p.174 / Chapter 4.2 --- Dissolution of metal sludge --- p.175 / Chapter 4.2.1 --- Dewatering and drying of metal sludge --- p.175 / Chapter 4.2.2 --- Dissolving of metal sludge by sulfuric acid --- p.175 / Chapter 4.3 --- Metal ion removal studies --- p.176 / Chapter 4.3.1 --- Selection of biomass --- p.176 / Chapter 4.3.2 --- Removal of Cu2+ in the concentrated Cu2+ solution by magnetite- immobilized cells --- p.178 / Chapter 4.4 --- Effects of EDTA on removal and recovery of Cu2+ by magnetite- immobilized cells --- p.182 / Chapter 4.4.1 --- Effects of EDTA --- p.182 / Chapter 4.4.2 --- Effects of EDTA after precipitation --- p.184 / Chapter 4.5 --- Effects of anions on removal and recovery of Cu2+ by magnetite- immobilized cells --- p.185 / Chapter 4.5.1 --- Effects of anions --- p.185 / Chapter 4.5.2 --- Effects of anions after precipitation --- p.188 / Chapter 4.5.3 --- Effects of anions in the presence of EDTA after precipitation --- p.190 / Chapter 4.6 --- Effects of other cations on removal and recovery of Cu2+ by magnetite-immobilized cells --- p.192 / Chapter 4.6.1 --- Effects of other cations --- p.192 / Chapter 4.6.2 --- Effects of other cations after precipitation --- p.195 / Chapter 4.6.3 --- Effects of other cations in the presence of EDTA after precipitation --- p.197 / Chapter 4.7 --- Maximum removal efficiency of Cu2+ by magnetite-immobilized cells --- p.198 / Chapter 4.8 --- Multiple adsorption-desorption cycles --- p.199 / Chapter 4.9 --- Treatment of electroplating effluent by magnetite-immobilized cells --- p.202 / Chapter 4.9.1 --- Removal and recovery of Cu2+ from electroplating effluent collected from rinsing baths --- p.202 / Chapter 4.9.2 --- Removal and recovery of Cu2+ from electroplating effluent collected from final collecting tank --- p.205 / Chapter 5. --- Conclusion --- p.213 / Chapter 6. --- Summary --- p.215 / Chapter 7. --- Recommendations --- p.219 / Chapter 8. --- References --- p.221

Thesis (M. Tech.: Biotechnology)-Dept. of Biotechnology and Food Technology, Durban University of Technology, 2008. xiv, 103 leaves : ill. / Phytoremediation is an emerging technology where specially selected and engineered metal-accumulating plants are used for bioremediation. Amaranthus dubius (marog or wild spinach) is a popular nutritious leafy vegetable crop which is widespread especially in the continents of Africa, Asia and South America. Their rapid growth and great biomass makes them some of the highest yielding leafy crops which may be beneficial for phytoremediation. This study was undertaken to evaluate the potential of A. dubius for the phytoremediation of Chromium (Cr), Mercury (Hg), Arsenic (As), Lead (Pb), Copper (Cu) and Nickel (Ni). Locally gathered soil and plants of A. dubius were investigated for the metals from a regularly cultivated area, a landfill site and a sewage site. Metals were extracted from the samples using microwave-digestion and analyzed using Inductively Coupled Plasma – Mass Spectroscopy (ICP-MS). Further experiments were conducted with plants from locally collected seeds of A. dubius, in a tunnel house under controlled conditions. The mode of phytoremediation, the effect of the metals on the plants, the ability of the plant to extract metals from soil (Bioconcentration Factor - BCF), and the ability of the plants to move the metals to the aerial parts of the plants (Translocation Factor - TF) were evaluated for the different metals. Finally, A. dubius was micro-propagated in a tissue culture system with and without exposure to the metal, and the effect was studied by electron microscopy.

published_or_final_version / Chemistry / Master / Master of Philosophy

by Li Sze Kwan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1990. / Bibliography: leaves 234-259. / ACKNOWLEDGEMENT --- p.i / ABSTRACT --- p.ii / CONTENTS : / Chapter CHAPTER 1: --- GENERAL INTRODUCTION --- p.1 / Chapter 1.1 --- Our Environment Is Polluted --- p.1 / Chapter 1.2 --- Heavy Metal Contamination --- p.3 / Chapter 1.3 --- The Effect of Cadmium and Some Related Metals on Environment --- p.5 / Chapter 1.4 --- The Uses of Microorganisms in Cleaning Up Environment --- p.9 / Chapter 1.5 --- Mechanisms of Cadmium Uptake in Cadmium Accumulating Strains --- p.10 / Chapter 1.6 --- Techniques for Cell Immobilization --- p.13 / Chapter 1.7 --- Prospect --- p.20 / Chapter CHAPTER 2: --- ISOLATION OF CADMUIM ACCUMULATNIG MICROORGANISMS --- p.22 / Chapter 2.1 --- Introduction --- p.22 / Chapter 2.2 --- Materials and Methods --- p.25 / Chapter 2.2.1 --- Recipes Used for Growing Various Organisms --- p.25 / Chapter 2.2.2 --- Methods Used for Collecting Organisms to be Tested --- p.27 / Chapter 2.2.3 --- Observation of Samples by Microscope --- p.28 / Chapter 2.2.4 --- Enrichment of Cadmium Resistant Microorganisms --- p.28 / Chapter 2.2.5 --- Selection and Isolation of Cadmium Resistant Microorganisms --- p.29 / Chapter 2.2.6 --- Purification of Microbial Colonies --- p.30 / Chapter 2.2.7 --- Preliminary Classification of Selected Microorganisms --- p.30 / Chapter 2.2.8 --- Screening of Cadmium Accumulating Strains --- p.30 / Chapter 2.2.9 --- Cadmium Analysis --- p.31 / Chapter 2.3 --- Result --- p.32 / Chapter 2.3.1 --- Selection of Cadmium Resistant --- p.32 / Chapter 2.3.2 --- Cadmium Resistance of Isolates --- p.36 / Chapter 2.3.3 --- Screening of Cadmium Accumulating Microorganisms --- p.38 / Chapter 2.4 --- Discussion --- p.39 / Chapter CHAPTER 3: --- GENERAL CHARACTERIZATION OF STRAIN 1000A --- p.43 / Chapter 3.1 --- Introduction --- p.43 / Chapter 3.1.1 --- Various Factors Affecting the Accumulation of Cadmium of Strain 1000A --- p.43 / Chapter 3.1.2 --- Identification --- p.44 / Chapter 3.2 --- Materials and Methods --- p.45 / Chapter 3.2.1 --- "Preparation of Solutions, Antibiotics and Reagents" --- p.45 / Chapter 3.2.2 --- Culture Media Used --- p.47 / Chapter 3.2.3 --- Growth Kenetics Determination --- p.48 / Chapter 3.2.4 --- Determination of the Effect of Cadmium Concentration on Cd-uptake in Free Cells --- p.49 / Chapter 3.2.5 --- Determination of the Effect of Phosphate Concentration on Cd-uptake in Free Cell --- p.49 / Chapter 3.2.6 --- Determination of the Cd-uptake in Free Cells in Continuous Cultures --- p.50 / Chapter 3.2.7 --- Determination of Antibiotic Resistance of Strain 1000A --- p.51 / Chapter 3.2.8 --- Dstermination of Relationship between Chloramphenicol Resistance and Cd-uptake --- p.52 / Chapter 3.2.9 --- Cadmium Analysis --- p.52 / Chapter 3.2.10 --- Determination of Inorganic Precipitation of Cadmium --- p.53 / Chapter 3.2.11 --- Assimilation Tests --- p.54 / Chapter 3.2.12 --- Identification of Strain 1000A --- p.55 / Chapter 3.3 --- Result --- p.55 / Chapter 3.3.1 --- Growth Kinetics of Strain 1000A in Cadmium Supplemented Peptone Medium --- p.55 / Chapter 3.3.2 --- Cd-uptake of Strain 1000A at Various Cadiuin Concentration --- p.65 / Chapter 3.3.3 --- Effect of Phosphate concentration on Cd-uptake of Strain 1000A --- p.65 / Chapter 3.3.4 --- Cd-uptake of Strain 1000A in Continuous Cultures --- p.70 / Chapter 3.3.5 --- Inorganic Precipitation of Cadmium Phosphate --- p.75 / Chapter 3.3.6 --- Determination of Antibiotic-Resistance of Strain 1000A --- p.78 / Chapter 3.3.7 --- Effect of Chloramphenicol on Cd-uptake and Cadmium Resistance of Strain 1000A --- p.82 / Chapter 3.3.8 --- Determination of the Effect of Tetracyclin --- p.85 / Chapter 3.3.9 --- Assimilation Tests --- p.94 / Chapter 3.3.10 --- Identification of Strain 1000A --- p.94 / Chapter 3.4 --- Discussion --- p.97 / Chapter CHAPTER 4: --- DETERMINATION OF CADMIUM UPTAKE MECHANISM IN P. PICKETTI 1000A --- p.102 / Chapter 4.1 --- Introduction --- p.102 / Chapter 4.2 --- Materials and Methods --- p.105 / Chapter 4.2.1 --- Preparation of Solutions and Reagents --- p.105 / Chapter 4.2.2 --- Preparation of Reagents for SDS-PAGE --- p.105 / Chapter 4.2.3 --- Recipes for Growing Cells --- p.107 / Chapter 4.2.4 --- Protein Determination --- p.108 / Chapter 4.2.5 --- Examination of Cadmium Accommodation in P. picketti 1000A by Transmission Electron Microscope --- p.108 / Chapter 4.2.6 --- SDS-polyacrylamide Gel Electrophoretic Determination of Protein Profiles --- p.109 / Chapter 4.2.7 --- Phosphate Assay --- p.111 / Chapter 4.2.8 --- Orthophosphate Estimation --- p.112 / Chapter 4.2.9 --- Sulphide Analysis --- p.112 / Chapter 4.2.10 --- Cadmium Analysis --- p.113 / Chapter 4.2.11 --- Cd-binding Determination through Column Separation --- p.113 / Chapter 4.2.12 --- Cd-binding Determinate ion through SDS Electrophoresis --- p.114 / Chapter 4.2.13 --- Determination of Cadmium Distribution of Cells --- p.115 / Chapter 4.3 --- Result --- p.116 / Chapter 4.3.1 --- SDS-PAGE Determination of Protein Profiles of P. picketti 1000A --- p.116 / Chapter 4.3.2 --- Determination of Cd-binding Protein of P. picketti 1000A --- p.121 / Chapter 4.3.3 --- "Determination of the Relationship of Cellular Cadmium, Sulphide and Phosphate" --- p.131 / Chapter 4.3.4 --- Examination of Cadmium Accumulation of P. picketti 1000A by Transmission Electron Microscope --- p.142 / Chapter 4.3.5 --- Cadmium Distribution of Cadmium-Accommodated Cells --- p.148 / Chapter 4.4 --- Discussion --- p.152 / Chapter CHAPTER 5: --- CORRELATION AMONG METALS IN HEAVY METAL UPTAKE --- p.158 / Chapter 5.1 --- Introduction --- p.158 / Chapter 5.2 --- Materials and Methods --- p.158 / Chapter 5.2.1 --- Preparation of Solutions --- p.159 / Chapter 5.2.2 --- "Determination of Effect of Zn+2 ," --- p.160 / Chapter 5.2.3 --- Determination of Effect of Cu+2 . --- p.161 / Chapter 5.2.4 --- "Correlation among Cd+2, Cu+2 and Zn+2" --- p.161 / Chapter 5.2.5 --- Growth Kenetics Determination --- p.162 / Chapter 5.2.6 --- Cell Sample Preparation --- p.162 / Chapter 5.2.7 --- Orthophosphate Estimation --- p.162 / Chapter 5.2.8 --- Metal Analysis --- p.163 / Chapter 5.3 --- Result --- p.163 / Chapter 5.3.1 --- Effect of Zn+2 --- p.163 / Chapter 5.3.2 --- Effect of Cu+2 --- p.173 / Chapter 5.3.3 --- "Correlation among Cd+2, Cu+2 and Zn+2" --- p.178 / Chapter 5.4 --- Discussion --- p.195 / Chapter CHAPTER 6: --- HEAVY METAL UPTAKE OF IMMOBILIZED CELL --- p.197 / Chapter 6.1 --- Introduction --- p.197 / Chapter 6.2 --- Materials and Methods --- p.199 / Chapter 6.2.1 --- Preparation of Solutions and Medium --- p.199 / Chapter 6.2.2 --- Harvesting of Cells --- p.199 / Chapter 6.2.3 --- Immobilization of Cells --- p.199 / Chapter 6.2.4 --- Determination of the Effect of Temperature --- p.200 / Chapter 6.2.5 --- Determination of Optimum Cell Concentration in Polyacrylamide Gel --- p.201 / Chapter 6.2.6 --- Determination of pH Effect on Cd-uptake --- p.201 / Chapter 6.2.7 --- Pretreatment with 70% Methanol --- p.202 / Chapter 6.2.8 --- Combined Pretreatment with Methanol and NaOH --- p.202 / Chapter 6.2.9 --- Effect of Phosphate on Cd-uptake of Immobilized Cell --- p.202 / Chapter 6.2.10 --- Comparison of Cadmium- and Copper-uptakes in Cells Immobilized in K-carrageenan and in Polyacrylamide --- p.203 / Chapter 6.3 --- Result --- p.204 / Chapter 6.3.1 --- Effect of Temperature on Cd-uptake --- p.204 / Chapter 6.3.2 --- Determination of Optimum Cell Concentration in Polyacrylamide Gel --- p.204 / Chapter 6.3.3 --- Effect of pH on Cd-uptake of Immobilized Cells --- p.207 / Chapter 6.3.4 --- Effect of Methanol on Cd-uptake --- p.210 / Chapter 6.3.5 --- Combined Effect of pH and Methanol on Cd-uptake --- p.213 / Chapter 6.3.6 --- Effect of Phosphate on Cd-uptake of Immobilized Cells --- p.213 / Chapter 6.3.7 --- Comparison between Cadmium- and Copper-uptake of Cells Immobilized in K-carrageenan and in Polyacrylamide --- p.220 / Chapter 6.4 --- Discussion --- p.228 / Chapter CHAPTER 7: --- CONCLUSION --- p.232 / REFERENCES --- p.234

No description available.

D. Tech. Chemical Engineering. / This research aims to improve the current state of wastewater treatment technologies by exploiting the characteristics and capabilities of nanomaterials. Also, it aims at protecting the environment and human health by minimizing exposure of toxic contaminants found in waters sources by treatment with cheaply engineered materials. The nanocomposites that will be employed in this study have shown to be effective for removing a number of heavy metals from aqueous solutions during trial experiment. The study is therefore carried out to reduce the water scarcity in South Africa by minimizing the contamination of remaining water resources. With industrial effluents the main targets, the aim is to design systems that will enable industries to recycle their wastewater instead of discharging into the environment. This study will therefore benefit the communities who solely depend on surface and ground water and again it will safe industrial bodies high costs of treating their wastewater with ineffective conventional methods. The research focuses on the application of polypyrrole-clay nanocomposites for removing heavy metals from wastewater streams. The research conducted hereby highlights the application of polymer based nanocomposites as suitable adsorbents for the remediation of the toxic chromium(VI) [Cr(VI)] from water. The work describes the preparation and characterization of the nanocomposites, their application to wastewater laden with Cr(VI) in both batch and continuous adsorption and finally understanding the adsorbent-adsorbate interactions and sorption mechanisms under various physico-chemical conditions.

D. Tech. Environmental, Water and Earth Sciences / Pollution of water sources with heavy metals is currently a global concern due to the detrimental effect of these metals on both human and animal health. To address this issue, biological treatment methods have been seen as the most effective and eco-friendly option of the available treatment processes of wastewater. The aim of this study was to compare the ability of selected bacterial isolates and indigenous protozoan to tolerate nickel and vanadium in wastewater systems in order to determine which group of organisms might play a major role in the removal of nickel and vanadium, even at high concentrations, in wastewater treatment systems.

Thesis (M. Tech.: Biotechnology)-Dept. of Biotechnology and Food Technology, Durban University of Technology, 2008. xiv, 103 leaves : ill. / Phytoremediation is an emerging technology where specially selected and engineered metal-accumulating plants are used for bioremediation. Amaranthus dubius (marog or wild spinach) is a popular nutritious leafy vegetable crop which is widespread especially in the continents of Africa, Asia and South America. Their rapid growth and great biomass makes them some of the highest yielding leafy crops which may be beneficial for phytoremediation. This study was undertaken to evaluate the potential of A. dubius for the phytoremediation of Chromium (Cr), Mercury (Hg), Arsenic (As), Lead (Pb), Copper (Cu) and Nickel (Ni). Locally gathered soil and plants of A. dubius were investigated for the metals from a regularly cultivated area, a landfill site and a sewage site. Metals were extracted from the samples using microwave-digestion and analyzed using Inductively Coupled Plasma – Mass Spectroscopy (ICP-MS). Further experiments were conducted with plants from locally collected seeds of A. dubius, in a tunnel house under controlled conditions. The mode of phytoremediation, the effect of the metals on the plants, the ability of the plant to extract metals from soil (Bioconcentration Factor - BCF), and the ability of the plants to move the metals to the aerial parts of the plants (Translocation Factor - TF) were evaluated for the different metals. Finally, A. dubius was micro-propagated in a tissue culture system with and without exposure to the metal, and the effect was studied by electron microscopy.

This project considered the use of the yeast Saccharomyces cerevisiae as a biosorbent for the removal and recovery of a range of metals from contaminated waters. S. cerevisiae, as a biosorbent, has the potential to provide a cost effective, selective and highly efficient purification system. Initial studies focused on metal accumulation by an immobilized baker's S. cerevisiae biosorbent. The parameters affecting metal uptake were investigated, these included metal concentration, time and solution pH. Metal uptake was rapid. Gold and cobalt reached saturation within 5 min of contact with the biosorbent in batch reactors. Copper, zinc, nickel, cadmium and chromium reached saturation within 30 min of contact. Metal accumulation was pH dependent and was generally unaffected at a solution pH ≥ 4, and was substantially decreased at pH ≤ 2. The exception was gold which was preferentially accumulated at a solution pH of 2. The immobilized baker's yeast accumulated metals with maximum binding capacities in the order of gold > cadmium > cobalt > zinc > copper > chromium > nickel. A rapid method to assess metal recovery was developed. Bioaccumulated metal was efficiently recovered using dilute mineral acids. Copper recovery of ≥ 80 % was achieved by decreasing the solution pH of the reaction mixture to 2 with the addition of nominal quantities of HCl, H₂SO₄ or RNO₃. Adsorption-desorption over 8 cycles had no apparent adverse effect on metal uptake or recovery in batch reactors. Transmission electron microscopy showed no evidence of damage to cells used in copper adsorption-desorption investigations. Biosorption columns were investigated as bioreactors due to their application potential. The metals investigated were effectively removed from solution. At a saturation threshold, metal uptake declined rapidly. Most metals investigated were desorbed from the columns by eluting with 0.1 M HCl. Initially recoveries of copper, cobalt and cadmium were as high as 100%. Desorbed copper, zinc, cadmium, nickel and cobalt were concentrated in 10 to 15 ml of eluent, representing up to a 40 fold decrease in solution volume. Cadmium, nickel and zinc uptake increased with the second application to the columns. Initial accumulation of gold and chromium was 42.2 μmol/g and 28.6 μmol/g, however, due to the low recoveries of these two metals, a second application was not investigated. Copper was applied to a single column for 8 consecutive adsorption-desorption cycles. Uptake increased from an initial 31.3 μmol/g to 47.8 μmol/g at cycle 7. The potential for selective metal recovery was demonstrated using two biosorption columns in series. Copper was accumulated and recovered most efficiently. Zinc, cobalt and cadmium were displaced to the second column. Copper bound preferentially to zinc at a ratio of 6:1. Copper bound preferentially to cobalt at a ratio of 4:1. Cadmium was only displaced at a ratio of 2:1. The successful transfer of the bioremediation technology from the laboratory to an industrial application has yet to be realized. Bioremediation of a Plaatjiesvlei Black Mountain mine effluent, which contained copper, zinc, lead and iron, was investigated in this project. The removal of the metals was most effective at pH 4. A combined strategy of pH adjustment and bioremediation using immobilized S. cerevisiae decreased the copper concentration by 92.5%, lead was decreased by 90% and zinc was decreased by 60%. Iron was mostly precipitated from solution at pH ≥ 4. An ageing pond at the mine with conditions such as; pH, water volume and metal concentration, which were more conducive to biological treatment was subsequently identified. The investigation indicated a possible application of the biomass as a supplement to chemical remediation. The metal removal capability of a waste brewer's yeast was subsequently investigated. A yeast conditioning step increased metal uptake up to 100% and enhanced reproducibility. Metal removal from solution was rapid and pH dependent. The metals were efficiently removed from solution at pH ≥ 4. Uptake was substantially inhibited at pH ≤ 3. The waste brewer's yeast accumulated metals with maximum binding capacities in the order of copper (25.4 μmol/g) > lead (19.4 μmol/g) > iron (15.6 μmol/g) > zinc (12.5 μmol/g). No correlation between cell physiology and metal uptake was observed. Uptake of the four metals was confirmed by energy dispersive X-ray microanalysis. The interference of lead, zinc and iron on copper uptake by the waste brewer's yeast, and the interference of copper on the uptake of lead, zinc and iron was investigated. Maximum copper uptake was not decreased in the presence of lead. The Bmax remained constant at approximately 25 μmol/g. The dissociation constants increased with increasing lead concentrations. Lead bioaccumulation was significantly decreased in the presence of copper. The type of inhibition was dependent on the initial copper concentrations. Zinc had a slight synergistic effect on copper uptake. The copper Bmax increased from 30.8 μmol/g in a single-ion system to 34.5 μmol/g in the presence of 200 μmol/l of zinc. Zinc uptake was severely inhibited in the presence of copper. The maximum uptake and dissociation constant values were decreased in the presence of copper, which suggested an uncompetitive inhibition. The affinity of copper was substantially higher than zinc. The presence of higher levels of copper than zinc in the yeast cells was confirmed by energy dispersive microanalysis. Copper uptake was decreased in the presence of iron, with the copper Bmax being decreased from 25.4 μmol/g in a single-ion system to 20.1 μmol/g in the presence of 200 μmol/l iron. Iron Bmax values remained constant at 16.0 μmol/g. Combined biosorption and EDXA results suggested the iron bound at a higher affinity than copper to the cell wall. Total copper removal was higher as larger quantities of copper were deposited in the cell cytoplasm. Metal removal from the Plaatjiesvlei effluent by free cell suspensions of the waste brewer's yeast was satisfactory. Copper levels were decreased by 96%, iron by 42%, lead 25% and zinc 2%. Waste brewer's yeast is a cheap source of biomass in South Africa, and could potentially provide the basis for the development of an innovative purification system for metal-contaminated waters.