Discharge of metal containing effluents into water has been a cause of major concern. Traditional treatment methods are proving to be ineffective and expensive. Chitosan was studied as a potential biosorbent due to its positive charge and relatively low cost. The study involves evaluating the metal binding performance of chitosan in a polymer enhanced diafiltration (PEDF) system which uses an ultrafiltration membrane to retain the chitosan which, in turn, binds the metal, thereby preventing passage into the permeate stream. Conditions for binding such as pH, concentration of polymer and chromium were studied. Optimal performance was obtained when the system was operated at pH values lower then the pKa of chitosan i.e. 6.3. Using 6 g/L chitosan at pH 4.0, chromium concentration was reduced to less than 1mg/L from a feed concentration of 20 mg/L. Equilibrium dialysis experiments were done to study the kinetics of binding and the uptake of metal per gram of polymer. Rheological measurements demonstrated that in the presence of 1-100 mM chromate, chitosan was found to be slightly shear-thickening at low concentrations such as 4 g/L and 6 g/L whereas it was slightly shear-thinning at higher concentrations like 12 g/L and 20 g/L This suggests that neutralization of chromium anions is due to the interaction of multiple chitosan molecules. This result is consistent with the relatively stiff nature of the polysaccharide. Overall, this study suggests that some modification of the native polymer would be required to improve uptake and make it an industrially workable process.

by So Lai Man, Rachel. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 83-103). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Abstract --- p.ii / Table of Contents --- p.iv / List of Figures --- p.viii / List of Tables --- p.ix / Chapter 1. --- Literature Review --- p.1 / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.2 --- Overview of metal ions pollution --- p.2 / Chapter 1.3 --- Treatment of metal ions in wastewater --- p.4 / Chapter 1.3.1 --- Conventional methods --- p.4 / Chapter 1.3.2 --- Microbial methods --- p.5 / Chapter 1.4 --- Phytoremediation --- p.6 / Chapter 1.4.1 --- Rhizofiltration --- p.10 / Chapter 1.4.2 --- Mechanisms of metal ion removal by plant root --- p.12 / Chapter 1.5 --- Using water hyacinth for wastewater treatment --- p.15 / Chapter 1.5.1 --- Biology of water hyacinth --- p.15 / Chapter 1.5.2 --- Water hyacinth based systems for wastewater treatment --- p.21 / Chapter 1.6 --- Biology of rhizosphere --- p.23 / Chapter 2. --- Objectives --- p.26 / Chapter 3 --- Materials and Methods --- p.28 / Chapter 3.1 --- Metal ion stock solution --- p.28 / Chapter 3.2 --- Plant material and growth conditions --- p.28 / Chapter 3.2.1 --- Preparation of Hoagland solution --- p.28 / Chapter 3.3 --- Metal ion resistance of water hyacinth --- p.31 / Chapter 3.4 --- Effect of metal ion concentration on the bacteria population --- p.31 / Chapter 3.4.1 --- Minimal medium (MM) --- p.31 / Chapter 3.5 --- Isolation of rhizospheric metal ion-resistant bacteria --- p.34 / Chapter 3.6 --- Metal ion removal capacity of isolated bacteria --- p.34 / Chapter 3.7 --- Colonization efficiency of a metal ion-adsorbing bacterium onto the root --- p.35 / Chapter 3.7.1 --- Suppression of the bacterial population in the rhizosphere by an antibiotic --- p.35 / Chapter 3.7.2 --- Colonization efficiency --- p.36 / Chapter 3.8 --- Effect of colonizing the metal ion-adsorbing bacteria on the metal ion removal capacity of roots --- p.37 / Chapter 4. --- Results --- p.38 / Chapter 4.1 --- Selection of optimum metal ion concentration for water hyacinth and rhizo spheric bacteria --- p.38 / Chapter 4.1.1 --- Metal ion resistance of water hyacinth --- p.38 / Chapter 4.1.2 --- Effect of metal ion concentration on population of rhizospheric bacteria --- p.43 / Chapter 4.1.3 --- Selection for optimum metal ion concentration for water hyacinth and rhizospheric bacteria --- p.43 / Chapter 4.2 --- Screening for bacterial strain with high metal ion resistance and removal capacity --- p.46 / Chapter 4.2.1 --- Enrichment of the metal ion-resistant bacteria in the rhizosphere --- p.46 / Chapter 4.2.2 --- Isolation of the natural bacterial population in rhizosphere --- p.50 / Chapter 4.2.3 --- Determination of the metal ion removal capacity of rhizospheric metal ion-resistant bacterial strains --- p.52 / Chapter 4.2.4 --- "Comparison of Cu2+, Ni2+ and Zn2+ removal capacities of Cu2+-resistant bacterial strains" --- p.53 / Chapter 4.3 --- Effect of inoculating Cu2+-resistant bacterial strain to the rhizosphere on the metal ion removal capacity of the root --- p.59 / Chapter 4.3.1 --- Bactericidal efficiency of oxytetracycline --- p.59 / Chapter 4.3.2 --- Effect of inoculating Cu2+-adsorbing bacterial cells into the rhizosphere --- p.62 / Chapter 4.3.3 --- Effect of bacterial cell density of inoculum on colonizing efficiency --- p.63 / Chapter 4.3.4 --- Colonizing efficiency and metal ion removal capacity of root by direct inoculation of metal ion-adsorbing bacterial cells into metal ion solution or pre-inoculation in Hoagland solution --- p.64 / Chapter 4.3.5 --- Effect of inoculating Strain FC-2-2 into the rhizosphere on the removal capacity of roots --- p.64 / Chapter 5. --- Discussion --- p.69 / Chapter 5.1 --- Selection of optimum metal ion concentration for water hyacinth and rhizospheric bacteria --- p.69 / Chapter 5.1.1 --- Metal resistance of water hyacinth --- p.69 / Chapter 5.1.2 --- Effect of metal ion concentration on population of rhizospheric bacteria population --- p.70 / Chapter 5.1.3 --- Selection for optimum concentration --- p.70 / Chapter 5.2 --- Screening for high metal ion-resistant and -removal bacterial strains --- p.71 / Chapter 5.2.1 --- Enrichment of the metal ion-resistant bacteria in the rhizosphere --- p.71 / Chapter 5.2.2 --- Select metal ion-resistant bacterial strain from the natural population in the rhizosphere --- p.72 / Chapter 5.2.3 --- Determination of the metal ion removal capacity of respective metal ion-resistant bacterial strain --- p.72 / Chapter 5.3 --- Effect of inoculating Cu2+-resistant bacterial strain in the rhizosphere on the metal ion removal capacity of the root --- p.74 / Chapter 5.3.1 --- Bactericidal efficiency of oxytetracycline --- p.74 / Chapter 5.3.2 --- Effect of inoculating Cu2十-adsorbing bacterial cells into the rhizosphere --- p.75 / Chapter 5.3.3 --- Effect inoculum cell density on the colonizing efficiency --- p.76 / Chapter 5.3.4 --- Comparison of colonizing efficiency and metal ion removal capacity of root by direct inoculation metal ion-adsorbing bacterial cells into metal solution or pre-inoculationin Hoagland solution --- p.77 / Chapter 5.3.5 --- Effect of inoculating strain FC-2-2 into the rhizosphere on the removal capacity of roots --- p.78 / Chapter 5.4 --- Limitation and future development --- p.79 / Chapter 6. --- Conclusion --- p.81 / Chapter 7. --- References --- p.83

No description available.

Wong, Kin Shing Kinson. / Thesis submitted in: November 2007. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 145-158). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Abstract --- p.ii / 摘要 --- p.v / Contents --- p.viii / List of figures --- p.xv / List of plates --- p.xx / List of tables --- p.xxi / Abbreviations --- p.xxiii / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Heavy metals --- p.1 / Chapter 1.1.1 --- Characteristics of heavy metals --- p.1 / Chapter 1.1.2 --- Heavy metal pollution in Hong Kong --- p.2 / Chapter 1.1.3 --- Common usage of heavy metals --- p.4 / Chapter 1.1.3.1 --- Copper --- p.4 / Chapter 1.1.3.2 --- Nickel --- p.4 / Chapter 1.1.3.3 --- Zinc --- p.5 / Chapter 1.1.4 --- Toxicity of heavy metals --- p.5 / Chapter 1.1.4.1 --- Copper --- p.6 / Chapter 1.1.4.2 --- Nickel --- p.7 / Chapter 1.1.4.3 --- Zinc --- p.7 / Chapter 1.1.5 --- Treatment techniques for metal ions --- p.8 / Chapter 1.1.5.1 --- Chemical precipitation --- p.9 / Chapter 1.1.5.2 --- Ion exchange --- p.10 / Chapter 1.1.5.3 --- Activated carbon adsorption --- p.10 / Chapter 1.2 --- Biosorption --- p.11 / Chapter 1.2.1 --- Definition of biosorption --- p.11 / Chapter 1.2.2 --- Mechanism --- p.12 / Chapter 1.2.3 --- Advantages of biosorption --- p.13 / Chapter 1.2.4 --- Selection of biosorbents --- p.15 / Chapter 1.3 --- Chitinous materials --- p.17 / Chapter 1.3.1 --- Background of chitin --- p.17 / Chapter 1.3.2 --- Structures of chitinous materials --- p.18 / Chapter 1.3.3 --- Sources of chitinous materials --- p.18 / Chapter 1.3.4 --- Application of chitinous materials --- p.20 / Chapter 1.3.5 --- Mechanism of metal ion adsorption by chitin --- p.22 / Chapter 1.4 --- Activated carbon --- p.25 / Chapter 1.4.1 --- Characteristics of activated carbon --- p.25 / Chapter 1.4.2 --- Applications of activated carbon --- p.26 / Chapter 1.4.3 --- Factors affecting adsorption ability of activated carbon --- p.27 / Chapter 1.4.4 --- Advantages and Disadvantages --- p.28 / Chapter 1.4.4.1 --- Advantages (Adsorption) --- p.28 / Chapter 1.4.4.2 --- Advantages (Regerneration) --- p.28 / Chapter 1.4.4.3 --- Disadvantages (Adsorption) --- p.28 / Chapter 1.4.4.4 --- Disadvantages (Regeneration) --- p.29 / Chapter 1.5 --- Cation exchange resin --- p.29 / Chapter 1.5.1 --- Usages of cation exchange resin --- p.29 / Chapter 1.5.2 --- Characteristics of cation exchange resin --- p.30 / Chapter 1.5.3 --- Disadvantages of using cation exchange resin --- p.30 / Chapter 1.6 --- Magnetite --- p.31 / Chapter 1.6.1 --- Reasons of using magnetite --- p.31 / Chapter 1.6.2 --- Characteristics of magnetite --- p.31 / Chapter 1.6.3 --- Immobilization by magnetite --- p.32 / Chapter 1.6.4 --- Advantages of using magnetite --- p.33 / Chapter 1.7 --- The biosorption experiment --- p.33 / Chapter 1.7.1 --- The batch biosorption experiment --- p.33 / Chapter 1.7.2 --- The adsorption isotherms --- p.34 / Chapter 1.7.2.1 --- The Langmuir adsorption isotherm --- p.34 / Chapter 1.7.2.2 --- The Freundlich adsorption isotherm --- p.36 / Chapter 2. --- Objectives --- p.38 / Chapter 3. --- Materials and methods --- p.39 / Chapter 3.1 --- Adsorbents --- p.39 / Chapter 3.1.1 --- Chitin A --- p.39 / Chapter 3.1.2 --- Pretreatment of chitin A --- p.39 / Chapter 3.1.3 --- Magnetite --- p.39 / Chapter 3.1.4 --- Activated carbon --- p.41 / Chapter 3.1.5 --- Cation exchange resin --- p.41 / Chapter 3.1.6 --- Pretreatment of cation exchange resin --- p.41 / Chapter 3.2 --- Chemicals --- p.43 / Chapter 3.2.1 --- Metal ion solution --- p.43 / Chapter 3.2.2 --- Buffer solution --- p.43 / Chapter 3.2.3 --- Standard solution --- p.43 / Chapter 3.3 --- Immobilization of chitin A by magnetite --- p.44 / Chapter 3.3.1 --- Effect of chitin A to magnetite ratio --- p.44 / Chapter 3.3.2 --- Effect of amount of chitin A and magnetite in a fixed ratio --- p.45 / Chapter 3.3.3 --- Effect of pH --- p.45 / Chapter 3.3.4 --- Effect of immobilization time --- p.46 / Chapter 3.3.5 --- Effect of temperature --- p.46 / Chapter 3.3.6 --- Effect of agitation rate --- p.46 / Chapter 3.3.7 --- Effect of salinity --- p.46 / Chapter 3.3.8 --- Mass production of magnetite-immobilized chitin A --- p.47 / Chapter 3.4 --- Batch adsorption experiment --- p.47 / Chapter 3.5 --- "Optimization of physicochemical condition on Cu2+，Ni2+ and Zn2+ adsorption by MCA, AC and CER" --- p.48 / Chapter 3.5.1 --- Effect of equilibrium pH --- p.48 / Chapter 3.5.2 --- Effect of amount of adsorbent --- p.49 / Chapter 3.5.3 --- Effect of retention time --- p.49 / Chapter 3.5.4 --- Effect of agitation rate --- p.49 / Chapter 3.5.5 --- Effect of temperature --- p.50 / Chapter 3.5.6 --- Effect of initial metal ion concentration --- p.50 / Chapter 3.5.7 --- Adsorption isotherms --- p.50 / Chapter 3.5.8 --- Dimensionless separation factor --- p.52 / Chapter 3.5.9 --- Kinetic parameters of adsorption --- p.52 / Chapter 3.5.10 --- Thermodynamic parameters of adsorption --- p.53 / Chapter 3.6 --- "Recovery of Cu2+, Ni2+ and Zn2+ from metal ion-laden MCA" --- p.54 / Chapter 3.6.1 --- Performances of various solutions on metal ion recovery --- p.54 / Chapter 3.6.2 --- Multiple adsorption and desorption cycles of metal ions --- p.55 / Chapter 3.7 --- Statistical analysis of data --- p.55 / Chapter 4. --- Results --- p.56 / Chapter 4.1 --- Immobilization of chitin A by magnetite --- p.56 / Chapter 4.1.1 --- Effect of chitin A to magnetite ratio --- p.56 / Chapter 4.1.2 --- Effect of amount of chitin A and magnetite in a fixed ratio --- p.59 / Chapter 4.1.3 --- Effect of pH --- p.59 / Chapter 4.1.4 --- Effect of immobilization time --- p.59 / Chapter 4.1.5 --- Effect of temperature --- p.59 / Chapter 4.1.6 --- Effect of agitation rate --- p.64 / Chapter 4.1.7 --- Effect of salinity --- p.64 / Chapter 4.1.8 --- Mass production of magnetite-immobilized chitin A --- p.64 / Chapter 4.2 --- Batch adsorption experiment --- p.67 / Chapter 4.2.1 --- Screening of adsorbents --- p.67 / Chapter 4.3 --- "Optimization of physicochemical condition on Cu2+, Ni2+ and Zn2+ adsorption by MCA, AC and CER" --- p.70 / Chapter 4.3.1 --- Effect of equilibrium pH --- p.70 / Chapter 4.3.2 --- Effect of amount of adsorbent --- p.74 / Chapter 4.3.3 --- Effect of retention time --- p.78 / Chapter 4.3.4 --- Effect of agitation rate --- p.82 / Chapter 4.3.5 --- Effect of temperature --- p.82 / Chapter 4.3.6 --- Effect of initial metal ion concentration --- p.86 / Chapter 4.3.7 --- Summary of optimized conditions for three metal ions --- p.87 / Chapter 4.3.8 --- Cost analysis of metal ion removal by three adsorbents --- p.87 / Chapter 4.3.9 --- Performance of reference adsorbents (AC and CER) --- p.87 / Chapter 4.3.10 --- Adsorption isotherms --- p.99 / Chapter 4.3.11 --- Dimensionless separation factor --- p.103 / Chapter 4.3.12 --- Kinetic parameters of adsorption --- p.106 / Chapter 4.3.13 --- Thermodynamic parameters of adsorption --- p.113 / Chapter 4.4 --- "Recovery of Cu2+, Ni2+ and Zn2+ from metal ion-laden MCA" --- p.113 / Chapter 4.4.1 --- Performances of various solutions on metal ion recovery --- p.113 / Chapter 4.4.2 --- Multiple adsorption and desorption cycles of metal ions --- p.117 / Chapter 5. --- Discussions --- p.121 / Chapter 5.1 --- Immobilization of chitin A by magnetite --- p.121 / Chapter 5.1.1 --- Effect of chitin A to magnetite ratio --- p.121 / Chapter 5.1.2 --- Effect of amount of chitin A and magnetite in a fixed ratio --- p.121 / Chapter 5.1.3 --- Effect of pH --- p.122 / Chapter 5.1.4 --- Effect of immobilization time --- p.122 / Chapter 5.1.5 --- Effect of temperature --- p.122 / Chapter 5.1.6 --- Effect of agitation rate --- p.123 / Chapter 5.1.7 --- Effect of salinity --- p.123 / Chapter 5.2 --- Batch adsorption experiment --- p.123 / Chapter 5.2.1 --- Screening of adsorbents --- p.123 / Chapter 5.3 --- "Optimization of physicochemical condition on Cu2+, Ni2+ and Zn2+ adsorption by MCA, AC and CER" --- p.124 / Chapter 5.3.1 --- Effect of equilibrium pH --- p.125 / Chapter 5.3.2 --- Effect of amount of adsorbent --- p.126 / Chapter 5.3.3 --- Effect of retention time --- p.127 / Chapter 5.3.4 --- Effect of agitation rate --- p.128 / Chapter 5.3.5 --- Effect of temperature --- p.128 / Chapter 5.3.6 --- Effect of initial metal ion concentration --- p.129 / Chapter 5.3.7 --- Summary of optimized conditions for three metal ions --- p.130 / Chapter 5.3.8 --- Cost analysis of metal ion removal by three adsorbents --- p.132 / Chapter 5.3.9 --- Performance of reference adsorbents (AC and CER) --- p.133 / Chapter 5.3.10 --- Adsorption isotherms --- p.133 / Chapter 5.3.11 --- Dimensionless separation factor --- p.135 / Chapter 5.3.12 --- Kinetic parameters of adsorption --- p.136 / Chapter 5.3.13 --- Thermodynamic parameters of adsorption --- p.139 / Chapter 5.4 --- "Recovery of Cu2+, Ni2+ and Zn2+ from metal ion-laden MCA" --- p.140 / Chapter 5.4.1 --- Performances of various solutions on metal ion recovery --- p.140 / Chapter 5.4.2 --- Multiple adsorption and desorption cycles of metal ions --- p.141 / Chapter 6. --- Conclusions --- p.143 / Chapter 7. --- References --- p.145

Polluted stormwater, if not treated, can compromise water quality throughout our hydrologic cycle, adversely affecting aquatic ecosystems. Common stormwater pollutants, copper and zinc, have been identified as primary toxicants in multiple freshwater and marine environments. For small-scale generators, stormwater management can be cumbersome and implementation of common BMPs impractical thus catch basins are popular though not the most environmentally conscious and sustainable option. This study aims to characterize the potential of a mobile media filter operation for the treatment and on-site recycling of catch basin stormwater. The removal capacities of various commercially available filter media (e.g. a common perlite; Earthlite™, a medium largely composed of biochars; and Filter33™, a proprietary porous medium) were measured using binary injection solutions modeled after local catch basin stormwater characteristics. The results of filtration experiments, rapid small-scale column tests (RSSCTs), indicate that the transport of metals in Perlite is primarily impacted by nonspecific sorption whereas in Earthlite™ and Filter33™ both nonspecific and specific sorption are present. For all media and experimentation, there was a consistent preferential uptake of copper such that copper displayed delayed arrival and/or greater removal than zinc. Moreover, the observed snow plow effects and concentration plateaus in Earthlite™ and Filter33™ RSSCTs suggest rate limited ion exchange and specific sorption in addition to ion competition. Earthlite™ exhibited an approach velocity dependent removal efficiency in the RSSCTs and pseudo second order uptake behavior for zinc in kinetic batch experiments. At the lab scale equivalent of the proposed field scale flow rate, Filter33™ displayed the greatest average zinc removal of 8.6 mg/g. In all, this research indicates that test parameters (i.e. pH, competitive ions solutions, empty bed contact time, flow rate) based on the natural environment and field scale operation can greatly impact removal efficiency in filter media.

M. Tech. Chemical Engineering / The lack of clean and fresh water has become a worldwide problem because of water pollution caused by industrialization. Contamination of natural water sources by heavy metal is a worldwide public health problem, leading to waterborne outbreaks of infectious hepatitis, viral gastroenteritis, and cancer. Therefore it very important to remove these toxic metal ions from municipal and industrial effluents in order to protect plants, animals and human beings from their adverse effect before discharging into natural water bodies. Although, several separation methods such as filtration, reverse osmosis and membrane technology have been developed to remove these toxic heavy metal ions from wastewater, however these conventional treatments technologies were found to be expensive on a sustainable basis. Adsorption process was identified as the most effective, and extensively used essential process in wastewater treatment, and in order for adsorption process to feasibly remove pollutants from wastewater, there should be a need for a suitable adsorbent which will have a large porous surface area, and a controllable porous structure. Through the application of nanotechnology, nano adsorbents can be developed as effective adsorbents to treat wastewater. The main objective of this project was to apply magnetic metal doped iron oxides as an efficient adsorption media for the removing of Cr(VI), Cd(II) and V(V) ions from wastewater.

M. Tech. Chemical Engineering. / In this study, nano-structure hydrotalcite material was used as an adsorbent for the removal of heavy metals of lead (Pb), nickel (Ni), cadmium (Cd) and cobalt (Co) from wastewater. It was observed that, in comparison with single component system (Ni, Cd and Co only), the presence of co-ions reduced the Ni (II), Cd (II) and Co (II) adsorption suggesting suppression of the desired ion by the presence of co-existing ions. The kinetic data fitted well to pseudo-second order model while the equilibrium data were satisfactorily described by Langmuir isotherm. The adsorption capacities of Ni (II), Cd (II) and Co (II) at pH 6.0 were found to be 142.8, 200 and 142.8 mg/g at 25oC.

M. Tech. Environmental Management / Investigates the possibility of using maize tassel powder as a solid phase extraction sorbent for the recovery of Ag, Au and Cu from aqueous solution. The surface characteristics of maize tassel and its ability to remove Ag, Au and Cu from aqueous solutions needed to be established before the preparation of maize tassel beads.

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

ABSTRACT Continuous flow column studies were conducted to characterize suspended sol ids and heavy metal reduct ions through sedimentation with varying overflow rates. The heavy metals tested were cadmium, zinc, copper, iron, lead, nickel and chromium. Stormwater derived samples spiked with street sweepings categorized into particle size ranges less than 500 microns in diameter were utilized in the research. Overflow rates investigated ranged from 28 to 3600 gallons per day per square foot. Theoretical predictions of suspended solids reductions with the application of Stoke's Law exceeded observed reductions for the continuous flow system. Performance curves for all reductions over the observed range of overflow rates are described by a parabolic relationship with the general equation as follows: Reduced fraction= a+ b(Overflow Rate - c) 2 where a, b and c are constants specific to each parameter. Similarities in performance curves for all metals indicate a dependence on suspended solids for reductions. Cadmium and chromium reductions were a function of overflow rate, but did not show a statistically significant dependence on initial total suspended solids concentration. Lead, copper, zinc and iron reductions were a function of initial total suspended solids concentration as well as overflow rate. Iron and nickel exhibited dependence on initial concentration of the specific metal for reductions, as well as dependence on overflow rate and initial total suspended solids concentration. The steady-state models selected from the results of this research for total suspended sol ids and each of the heavy metals are limited to the mixture, specific experimental conditions, and range of overflow rates observed in this research. Observed reductions of total suspended solids and heavy metals are considered to be 1 imited to physical sedimentation processes, in that processes that may effect reductions of these elements in a natural system are not factors in the results of this research.