by Wong Suk Ying. / Thesis submitted in: November 2001. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 144-157). / Text in English; abstracts in English and Chinese. / by Wong Suk Ying. / Acknowledgments --- p.i / Abstract --- p.ii / Contents --- p.v / List of Figures --- p.x / List of Tables --- p.xvi / Chapter 1. --- INTRODUCTION --- p.1 / Chapter 1.1 --- Electroplating Industry in Hong Kong --- p.1 / Chapter 1.1.1 --- Typical stages in electroplating process --- p.1 / Chapter 1.1.1.1 --- Pre-treatment --- p.1 / Chapter 1.1.1.2 --- Electroplating --- p.3 / Chapter 1.1.1.3 --- Post-treatment --- p.3 / Chapter 1.1.2 --- Typical characteristics of wastestreams from electroplating industry --- p.3 / Chapter 1.2 --- Chemical Specific Approach against Toxicity Based Approach --- p.6 / Chapter 1.3 --- Ecotoxicological Study on Electroplating Effluent --- p.7 / Chapter 1.4 --- Toxicity Identification Evaluation --- p.8 / Chapter 1.4.1 --- Phase I: Toxicity Characterization --- p.9 / Chapter 1.4.2 --- Phase II: Toxicity Identification --- p.10 / Chapter 1.4.3 --- Phase III: Toxicity Confirmation --- p.12 / Chapter 1.5 --- Toxicity Identification Evaluation on Electroplating Effluent --- p.14 / Chapter 1.6 --- Selection of Organisms for Bioassays --- p.15 / Chapter 1.6.1 --- Organism used for toxicity identification evaluation --- p.17 / Chapter 2. --- OBJECTIVES --- p.20 / Chapter 3. --- MATERIALS AND METHODS --- p.21 / Chapter 3.1 --- Source of Samples --- p.21 / Chapter 3.2 --- Toxicity Identification Evaluation: Phase I Baseline Toxicity Test --- p.21 / Chapter 3.2.1 --- Microtox® test --- p.23 / Chapter 3.2.2 --- Growth inhibition test of a marine unicellular microalga Chlorella pyrenoidosa CU-2 --- p.25 / Chapter 3.2.3 --- Survival test of a marine amphipod Hylae crassicornis --- p.28 / Chapter 3.2.4 --- Survival test of a marine shrimp juvenile Metapenaeus ensis --- p.31 / Chapter 3.3 --- Toxicity Identification Evaluation: Phase I Toxicity Characterization --- p.34 / Chapter 3.3.1 --- pH adjustment filtration test --- p.35 / Chapter 3.3.2 --- Aeration test --- p.36 / Chapter 3.3.3 --- C18 solid phase extraction test --- p.37 / Chapter 3.3.4 --- EDTA chelation test --- p.38 / Chapter 3.3.5 --- Graduated pH test --- p.40 / Chapter 3.4 --- Toxicity Identification Evaluation: Phase II Toxicity Identification --- p.41 / Chapter 3.4.1 --- Filter extraction test --- p.41 / Chapter 3.4.2 --- Total metal content analysis --- p.42 / Chapter 3.5 --- Toxicity Identification Evaluation: Phase III Toxicity Confirmation --- p.43 / Chapter 3.5.1 --- Chemicals --- p.44 / Chapter 3.5.2 --- Mass balance test --- p.44 / Chapter 3.5.3 --- Spiking test --- p.44 / Chapter 4. --- RESULTS --- p.46 / Chapter 4.1 --- Chemical Characteristics of the Electroplating Effluent Samples --- p.46 / Chapter 4.2 --- Toxicity Identification Evaluation: Phase I Baseline Toxicity --- p.46 / Chapter 4.2.1 --- Toxicity of electroplating effluent samples on Microtox® test --- p.46 / Chapter 4.2.2 --- Toxicity of electroplating effluent samples on growth inhibition test of microalga Chlorella pyrenoidosa CU-2 --- p.46 / Chapter 4.2.3 --- Toxicity of electroplating effluent samples on survival test of amphipod Hyale crassicornis --- p.52 / Chapter 4.2.4 --- Toxicity of electroplating effluent samples on survival test of shrimp juvenile Metapenaeus ensis --- p.52 / Chapter 4.3 --- Toxicity Identification Evaluation: Phase I Toxicity Characterization --- p.52 / Chapter 4.3.1 --- Toxicity Characterization of electroplating effluent samples using Microtox® test --- p.56 / Chapter 4.3.2 --- Toxicity Characterization of electroplating effluent samples using microalgal growth inhibition test of Chlorella pyrenoidosa CU-2 --- p.59 / Chapter 4.3.3 --- Toxicity Characterization of electroplating effluent samples using survival test of amphipod Hyale crassicornis --- p.65 / Chapter 4.3.4 --- Toxicity Characterization of electroplating effluent samples using survival test of shrimp juvenile Metapenaeus ensis --- p.68 / Chapter 4.4 --- Toxicity Identification Evaluation: Phase II Toxicity Identification --- p.73 / Chapter 4.4.1 --- Metal analysis on the electroplating effluents --- p.75 / Chapter 4.4.2 --- Effect of filter extraction test on toxicity recovery of the electroplating effluent samples --- p.75 / Chapter 4.4.2.1 --- Microtox® test --- p.75 / Chapter 4.4.2.2 --- Growth inhibition test of microalga Chlorella pyrenoidosa CU-2 --- p.75 / Chapter 4.4.2.3 --- Survival test of amphipod Hyale crassicornis --- p.81 / Chapter 4.4.2.4 --- Survival test of shrimp juvenile Metapenaeus ensis --- p.90 / Chapter 4.4.3 --- Effect of filter extraction test on metal ions recovery of the electroplating effluent samples --- p.90 / Chapter 4.5 --- Toxicity Identification Evaluation: Phase III Toxicity Confirmation --- p.96 / Chapter 4.5.1 --- Mass balance test results on Microtox® test --- p.96 / Chapter 4.5.2 --- Mass balance test results on survival test of amphipod Hyale crassicornis --- p.104 / Chapter 4.5.3 --- Spiking test results on Microtox® test --- p.106 / Chapter 4.5.4 --- Spiking test results on survival test of amphipod Hyale crassicornis --- p.113 / Chapter 5. --- DISCUSSION --- p.118 / Chapter 5.1 --- Toxicity Identification Evaluation: Phase I Baseline Toxicity --- p.118 / Chapter 5.2 --- Toxicity Identification Evaluation: Phase I Toxicity Characterization --- p.119 / Chapter 5.2.1 --- pH adjustment filtration test --- p.119 / Chapter 5.2.2 --- Aeration test --- p.120 / Chapter 5.2.3 --- C18 solid phase extraction test --- p.120 / Chapter 5.2.4 --- EDTA chelation test --- p.120 / Chapter 5.2.5 --- Graduated pH test --- p.121 / Chapter 5.3 --- Toxicity Identification Evaluation: Phase II Toxicity Identification --- p.122 / Chapter 5.3.1 --- Metal analysis on the electroplating effluents --- p.122 / Chapter 5.3.2 --- Effect of filter extraction test on toxicity and metal ions recovery of the electroplating effluent samples --- p.123 / Chapter 5.3.3 --- Comparison between the concentrations of the metal ions in the electroplating effluent samples with the Technical Memorandum on standards for effluent discharged --- p.124 / Chapter 5.3.4 --- Comparison between the concentrations of the metal ions in the electroplating effluent samples with the toxicity of the metal ions reported in the literature --- p.124 / Chapter 5.3.4.1 --- Microtox® test --- p.126 / Chapter 5.3.4.2 --- Microalga --- p.126 / Chapter 5.3.4.3 --- Amphipod --- p.126 / Chapter 5.3.4.4 --- Shrimp --- p.126 / Chapter 5.4 --- Toxicity Identification Evaluation: Phase III Toxicity Confirmation --- p.131 / Chapter 5.4.1 --- Mass balance test on Microtox® test --- p.132 / Chapter 5.4.2 --- Mass balance test on survival test of amphipod Hyale crassicornis --- p.133 / Chapter 5.4.3 --- Spiking test on Microtox® test --- p.133 / Chapter 5.4.4 --- Spiking test on survival test of amphipod Hyale crassicornis --- p.134 / Chapter 5.5 --- Toxicity of the Metal Ions Identified as the Toxicants in the Electroplating Effluent --- p.135 / Chapter 5.5.1 --- Copper --- p.135 / Chapter 5.5.2 --- Nickel --- p.137 / Chapter 5.5.3 --- Zinc --- p.138 / Chapter 5.6 --- Summary --- p.140 / Chapter 6. --- CONCLUSIONS --- p.142 / Chapter 7. --- REFERENCES --- p.144 / Chapter 7.1 --- APPENDIXES --- p.158

Submitted in fulfilment of the requirements of the egree of Master of Technology: Chemical Engineering, Durban University of Technology, 2011. / The South African electroplating industry generates large volumes of hazardous waste water that has to be treated prior to disposal. The main source of this waste water has been the rinse system. Conventional end-ofpipe waste water treatment technologies do not meet municipality standards. The use of technologies such as membranes, reverse osmosis and ion exchange are impractical, mainly due to their cost and technical requirements. This study identified source point reduction technologies, close circuiting of the electroplating process, specific to the rinse system as a key development. Specifically the application of a low flow counter current rinse system for the recovery of the rinse water in the plating bath was selected. However, the recovery of the rinse tank water was impeded by the low rates of evaporation from the plating bath, which was especially prevalent in the low temperature operating plating baths. This master’s study proposes the use of an induced draft evaporative cooling tower for facilitation of evaporation in the plating bath. For total recovery of the rinse tank water, the rate of evaporation from the plating bath has to be equivalent to the rinse tanks make up water requirements. A closed circuit plating system mathematical model was developed for the determination of the mass evaporated from the plating bath and the cooling tower for a specified time and the equilibrium temperature of the plating bath and the cooling tower. The key criteria in the development of the closed circuit plating system model was the requirement of minimum solution specific data as this information is not readily available. The closed circuit plating system model was categorised into the unsteady state and steady state temperature regions and was developed for the condition of water evaporation only. The closed circuit plating system model was programmed into Matlab and verified. The key factors affecting the performance of the closed circuit plating system were identified as the plating solution composition and operational temperature, ambient air temperature, air flow rate and cooling tower iv packing surface area. Each of these factors was individually and simultaneously varied to determine their sensitivity on the rate of water evaporation and the equilibrium temperature of the plating bath and cooling tower. The results indicated that the upper limit plating solution operational temperature, high air flow rates, low ambient air temperature and large packing surface area provided the greatest water evaporation rates and the largest temperature drop across the height of the cooling tower in the unsteady state temperature region. The final equilibrium temperature of the plating bath and the cooling tower is dependent on the ambient air temperature. The only exception is that at low ambient air temperatures the rate of water evaporation from the steady state temperature region is lower than that at higher ambient air temperatures. Thus the model will enable the electroplater to identify the optimum operating conditions for close circuiting of the electroplating process. It is recommended that the model be validated against practical data either by the construction of a laboratory scale induced draft evaporative cooling tower or by the application of the induced draft evaporative cooling tower in an electroplating facility.

Theoretical waste minimisation opportunities and options for electroplating were sought from the literature. Their suitability under the specific site conditions of a chromium electroplating plant were evaluated using the results of a waste minimisation audit (audit). The audit showed that many waste minimisation practices were already in place. These included counter current flowing rinse systems, multiple use of rinses and recycling of the drag-out solution back into the plating solution. Two types of information were collected during the audit, namely new chemical monitoring (concentration levels of sodium, iron, zinc, copper, lead, chromium and nickel and conductivity, total dissolved solids and pH) and flow rate data and existing data (composition of the process solutions, products and waste outputs, and raw materials, workpieces and utility inputs). The data were analysed using four established waste minimisation techniques. The Scoping Audit and the Water Economy Assessment results were determined using empirically derived models while the Mass Balancing and the True Cost of Waste results were obtained through more detailed calculations. The results of the audit showed that the three most important areas for waste minimisation were water usage, effluent from rinse water waste streams and nickel consumption. Water usage has the highest waste minimisation potential followed by nickel. Dragged-out process chemicals and rinse water consumption contribute to ranking the effluent stream the most important waste minimisation opportunity identified by the True Cost of Waste Analysis. Potential financial savings were roughly estimated to be in the order of R 19949 and R 126603 for water and nickel respectively. Intervention using only "low cost-no-cost" waste minimisation measures was recommended as a first step before contemplating further focus areas or technical or economical feasibility. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2004.

A chromium plating line used by a local company was monitored to identify any potential waste minimisation opportunities. Plating of the workpiece surface is carried out by immersing the workpiece in seven process (treatment) solutions including nickel and chromium plating baths. Between each process step the workpieces are rinsed. The chromium plating process was evaluated using the results of a waste minimisation audit. This involved gathering data on the composition, flow rates and costs of the inputs of the process. Two types of data were collected namely new and existing data. The new data included chemical monitoring (concentration levels of Ni, Cr, Na, S, B, P, Si, Fe, Cu, Zn, Pb as well as conductivity, TDS, SS and pH measurements) and water usage data. The existing data included raw materials, utility inputs, composition of process solutions and product outputs. The data were analysed using three established waste minimisation techniques. The Water Economy Assessment (a form of Monitoring and Targeting) results were determined using an empirically derived model. The Water Balance and True Cost of Waste results were obtained through more detailed calculations using the results of the chemical analysis. The results from the audit showed that the water usage on the chromium plating line has the highest waste minimisation potential. The True Cost of Waste analysis showed there is no significant chemical wastage in the effluent stream. The potential savings of the effluent stream was negligible (approximately R10 for 238 days). Drag-out calculations were also performed and showed that the drag-out volumes were in good agreement with the typical volumes found in the metal finishing industry. Intervention using simple lowcost and no-cost waste minimisation opportunities were recommended as a first step before contemplating further focus areas for technical or feasibility studies. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2009.