by Kwok Shu Cheung, Eric. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1990. / Bibliography: leaves 89-106. / Acknowledgement --- p.i / Abstract --- p.ii / Introduction / Chapter A. --- Objective --- p.1 / Chapter B. --- Literature Review / Chapter 1. --- Electroplating industry in Hong Kong and its impact on the environment --- p.7 / Chapter 2. --- Physical and chemical methods for removing heavy metals from electroplating effluent --- p.11 / Chapter 3. --- Removal of heavy metals by conventional activated sludge process --- p.16 / Chapter 4. --- Acclimation of wastewater bacteria to heavy metals --- p.26 / Chapter 5. --- Biosorbent and its role in metal detoxification --- p.28 / Materials and Methods / Chapter A. --- Isolation and selection of nickel-resistant bacteria --- p.32 / Chapter B. --- Culture medium and solution --- p.33 / Chapter C. --- Growth of organism --- p.33 / Chapter D. --- Immobilization of bacterial cells --- p.36 / Chapter E. --- Effect of growth conditions on nickel removal capacity of immobilized Enterobacter sp. cells --- p.37 / Chapter F. --- Effect of bioreactor operational conditions on the Ni2+ removal capacity of immobilized bacterial cells --- p.38 / Chapter G. --- Optimization of nickel removal efficiency of bioreactor --- p.39 / Chapter H. --- Determination of Ni2+ adsorption isotherm of immobilized cells of Enterobacter sp. --- p.39 / Chapter I. --- Recovery of nickel from the bioreactor --- p.40 / Chapter J. --- Activity of the regenerated bioreactor --- p.41 / Chapter K. --- Removal of Ni2+ from synthetic effluent by bioreactor --- p.41 / Chapter L. --- Removal of Ni2+ from electroplating effluent by bioreactor. --- p.41 / Chapter M. --- Production of immobilized bacterial cells by replacement of D-glucose by molasses in the growth medium --- p.42 / Results / Chapter A. --- Isolation and selection of nickel resistant bacteria --- p.44 / Chapter B. --- Effect of growth conditions on nickel removal capacity of immobilized Enterobacter sp. cells / Chapter 1. --- Nutrient limitation --- p.44 / Chapter 2. --- D-glucose concentration --- p.45 / Chapter 3. --- Incubation temperature and incubation time --- p.45 / Chapter C. --- Heavy metal removal capacity of immobilized cells of Enterobacter sp. --- p.50 / Chapter D. --- Effect of bioreactor operational conditions on Ni2+ removal capacity of the immobilized bacterial cells --- p.50 / Chapter E. --- Optimization of nickel removal efficiency of bioreactor --- p.55 / Chapter F. --- Determination of Ni2+ adsorption isotherm of immobilized cells of Enterobacter --- p.57 / Chapter G. --- Recovery of nickel from the bioreactor and activity of regenerated bioreactor against a fresh nickel flow --- p.61 / Chapter H. --- Removal of Ni2+ from synthetic effluent by bioreactor --- p.61 / Chapter I. --- Removal of Ni2+ from electroplating effluent by bioreactor. --- p.64 / Chapter J. --- Production of immobilized bacterial cells by replacement of D-glucose by molasses in the growth medium --- p.68 / Discussions / Chapter A. --- Effect of growth conditions on nickel removal capacity of immobilized Enterobacter sp. cells --- p.70 / Chapter B. --- Heavy metal removal capacity of immobilized cells of Enterobacter sp. --- p.73 / Chapter C. --- Effect of bioreactor operational conditions on Ni2+ removal capacity of the immobilized bacterial cells --- p.74 / Chapter D. --- Optimization of nickel removal efficiency of bioreactor --- p.74 / Chapter E. --- Determination of Ni2+ adsorption isotherm of immobilized cells of Enterobacter sp. --- p.76 / Chapter F. --- Recovery of nickel from the bioreactor and activity of the regenerated bioreactor against a fresh nickel flow --- p.77 / Chapter G. --- Removal of Ni2+ from synthetic effluent by bioreactor --- p.78 / Chapter H. --- Removal of Ni2+ from electroplating effluent by bioreactor --- p.79 / Chapter I. --- Production of immobilized bacterial cells by replacement of D-glucose by molasses in the growth medium --- p.82 / Chapter J. --- Further considerations of applicability of immobilized Enterobacter sp. cells to treatment of electroplating effluent --- p.83 / Conclusions --- p.86 / References --- p.89

This study was designed to develop an in-situ flushing system for remediating metal-contaminated soils. Specifically, the capabilities of citric acid, an organic acid, to extract metal ions from a metal-contaminated sandy soil, containing 0.42, 0.04, 0.01, and 41.52 mg g-1 of Zn, Cu, Cd, and Pb, respectively, were tested at bench-scale and large-scale levels. Citric acid, at pH 5.5, was used at different levels of concentration and retention time in batch experiments to establish optimum conditions for the maximum removal of heavy metals from the soil. Citric acid exhibited a tremendous potential to extract metal ions from the metal-contaminated soil. The extraction of metal ions increased with an increase in citric acid concentration. A column study (height = 0.6 m; internal diameter = 0.1 m) was conducted to compare metal leaching with surface and subsurface application of citric acid. The results indicated that the subsurface application resulted in a more efficient extraction of metal ions due to uniform distribution of the citric acid. / Finally, a large-scale experiment involving soil columns (height = 1.0 m; internal diameter = 0.2 m) was carried out to develop an in situ soil flushing system to remediate the metal-contaminated soil. Citric acid was supplied into the soil columns through a subsurface irrigation system. This process resulted in an overall extraction of Zn, Cu, Cd, and Pb ions from the soil columns at 83.27%, 1.47%, 16.70%, and 26.55%, respectively. Results obtained in different experimental protocols suggested that continuous flushing of the soil is a suitable method for extracting metal ions from the contaminated soil using citric acid. / The metal-rich leachate was effectively treated with chitosan flakes. Results indicate that for 0.1 M citric acid leachate containing 0.06, 0.02, 0.003, and 5.87 mumoles ml-1 of Zn, Cu, Cd, and Pb, respectively, about 20 g of chitosan would be sufficient to remove about 50% of the contaminants from one liter of leachate in 6 h. Various batch experiments involving pure solutions of metal ions as well as the metal-rich leachate were conducted to establish the metal adsorption properties of chitosan under various physico-chemical conditions. The controlled parameters were the amount of chitosan, reaction time with and without shaking, and the pH of the solution. The sorption of metal ions from pure metal solutions and the leachate was not improved by the agitation, and the maximum adsorption of metal ions onto chitosan flakes occurred at pH 6.0. Sorption equilibrium studies were also conducted with a constant sorbent weight and varying initial concentration of metal ions. The experimental data of adsorption from the solutions, containing metal ions, were found to correlate well with the Langmuir isotherm equation.

Thesis (MTech (Environmental Health))--Cape Peninsula University of Technology, 2011. / World wide urban rivers are the most utilised and degraded. A variety of everyday sources of metal pollution exist that is entrenched in the modern way of life. Lately there has been a tremendous growth in the establishment and development of human settlements, both formal and informal in the Cape Town area. The surroundings of the Kuils River are not excluded from this. There are various communities in close proximity to the Kuils River. Due to this, more industries are also being established. This has caused an increased production of potential environmental pollutants, including metals. The aim of the study was firstly, to identify potential sources of metal pollution along the entire length of the Kuils River, in order to identify sampling sites. Secondly, to identify the metals contaminating the water and sediment of the Kuils River. Thirdly, to determine the bioaccumulation of metals in freshwater snails (Physa ecuta). Four sampling sites were identified along the Kuils River. Freshwater snails (P. acuta), sediment and water were collected every 2 months for a period of one year. The following metals were investigated: Aluminium (AI), Cadmium (Cd) Cobalt (Co), Chromium (Cr), Copper (Cu), Iron (Fe), Lead (Pb), Manganese (Mn), Nickel (Ni.) and Zinc (Zn). Samples were digested with 55% nitric acid. The Inductively Coupled Plasma - Atomic Emission Spectrometer (ICP-AES) were used for metal analyses. The results were statistically analysed by means of ANOVA on ranks using the Sigmastat statistical package. Results revealed that most metals found in water, sediment and snails had significantly higher concentrations at site 1. This is possibly due to input from the surrounding urban area and nearly agricultural activities. Water concentrations of AI, Cu, Mn and Zn were higher than the DWAF (1996) guidelines. Sediment was mostly contaminated with AI, Fe, Pb and Zn, while the snails contained significant levels of Cu, Fe, Mn and Zn. Further investigations involving toxicity testing should be conducted to determine the toxicity of these metals to (Physa acuta).

No description available.

No description available.

The present study examines the cycling of elements in the biosphere. The first chapter proposes a theoretical framework for this cycling based on both metal/ligand theory and mass balance studies. Empirical modelling serves as an alternative and complement to mass balance studies in predicting the export of elements from watersheds. Watershed output (export per unit area per unit of time) is predicted using atmospheric deposition rates, an element bonding strength index, the watershed area and a forest classification (deciduous vs coniferous). Finally the last chapter examines, in a speculative fashion, the partitioning of elements between the atmosphere and hydrosphere as a function of element behaviour and discusses the ecological consequences of human activity on this partitioning.

There is a public concern over the potential accumulation of heavy metals in soils. Numerous studies have already demonstrated that areas in close proximity to vehicular traffic are marked noticeably by contamination of soil, air and water. Hence, such activities can affect humans and other living organisms. The aim of this study is to investigate the pollution of soils caused by vehicular traffic, on agricultural land in Azzawiyah, Liby with the view of assessing potential application of phytoremediation options for the remediation of contaminated soils and determine whether soil amendments would improve soil remediation. In an effort to improve the status of pollution of soils by vehicular traffic, a phytoremediation method of remediation of contaminated land has been used in this study, as it is relatively inexpensive and has the potential through the appropriate selection of plant species to be effective. This method is a soil clean up technology that uses the ability of metal accumulator plants to extract metal from contaminated soil with their roots and to concentrate these metals in above-ground plant parts. In this study, the investigation area was in Azzawiyah city where the soil samples and Doedonea viscose plant were collected from the road side. These soil samples were analysed using different experiments to determine physical and chemical properties, such as pH, OM and CEC. Heavy metals in soil and Doedonea viscose shoot and root were analysed using inductively coupled plasma atomic emission spectroscopy (ICP-AES). The findings of the study show that all soils samples collected along the highway road connecting Azzawiyah with the southern parts of Libya were found to be granular with a sandy texture. It is also found that the metal content in soil collected from the site, which is close to the roadside was relatively higher than that soil collected from the agricultural field in the same area. Furthermore, the level of Pb (840mg/kg-1) in roadside soils was higher than the natural levels of Pb in soils. In addition, Doedonea viscose plant was not a hyperaccumulor plant. Greenhouse experiments used three plants (E. camaldeulensis, Brassica Juncea and Medicago sativum) to uptake heavy metal, such as Cd, Zn and Pb from the soil samples. The greenhouse experiment results indicate that E. camaldeulensis was the best plant species for phytoremediation of Pb contaminated soils than the other two plants species (Brassica Juncea, Medicago sativum). The efficiency of the E. camaldeulensis was increased by adding amendments (e.g. compost, compost, EDTA, Hoagland solution and Alcaligenes eutrophus) to the plants pots in order to uptake the lead form soil samples. The results of the pots amendments experiments indicate that 15 mmol of EDTA and bacterial inoculums (Alcaligenes eutrophus) were the best amendments to extract lead from the soils. The study suggests that using the Alcaligenes eutrophus with the E. camaldeulensis are more suitable for phytoremediation in terms of accumulation and cost.

No description available.

M.Sc. (Zoology) / Please refer to full text to view abstract

M.Sc. / Please refer to full text to view abstract