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Thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Technology: Department of Chemical Engineering, Durban University of Technology, 2007. / The metal finishing industry has been rated among the most polluting industries worldwide. This industry has traditionally been responsible for the release of heavy metals such as chrome, nickel, tin, copper etc into the environment. The application of cleaner production systems to a range of industries, including the metal finishing industry has provided significant financial and environmental benefits. An example of a successful application cleaner production in the metal finishing industry is the reduction in the typical water consumption from 400 1/m² to less than 10 1/m² of plated product. The successful application of cleaner production to the mental finishing industry has encountered many barriers. These barriers include the need for a highly skilled cleaner production auditor and the need for rigorous plant data to effectively quantify the cleaner production potential of the company under consideration. This study focuses on providing an alternate user-friendly audit system for the implementation of cleaner production in the mental finishing industry. The audit system proposed eliminates the need for the need for both a technical auditor and rigid plant data. The proposed system functions solely on plant operator inputs. The operator’s knowledge is harnessed and used to conduct an efficient and effective cleaner production audit. The research is based on expert knowledge, which was gained by conducting audits on some 25 companies using traditional auditing tools. This company audits were used to construct a database of data that was used in the verification of the models developed in this study. The audit is separated into different focus components. The first system developed was based on fuzzy logic multi variable decision-making. For this system the plant was categorized into different sections and appropriate fuzzy ratings were allocated based on experience. Once the allocations were completed multi variable decision analysis was used to determine the individual variable impact. The output was compared and regressed to the database equivalent. Operator inputs can then be used to determine the individual category outputs for the cleaner for the production rating for the company under consideration. The second part of this study entails the development of mathematical models for the quantification of chemical and water consumptions. This was based on the present and ideal (cleaner production) plant configuration. Cleaner production operations are compared to present operations and potential savings quantified. Mathematical models were developed based on pilot scale experiments for the acid, degreaser and zinc plating process. The pilot experiments were carried out on a PLC controlled pilot plant. These models were developed form factorial experimentation on the variables of each of the plating processes. The models developed aid in the prediction of the relevant optimum consumptions. The key challenge in traditional evaluation systems has been the quantification of the plant production. The most effective measure of production is by means of the surface area plated. In this study a novel approach using the modeled acid consumption is proposed. It was assumed that the operator inputs for the above models would not be precise. The models developed allowed for input variations. These variations were incorporated into the model using the Monte Carlo technique. The entire cleaner production evaluation system proposed is based on an operator questionnaire, which is completed in visual basic. The mathematical model was incorporated into the visual basic model. For the purpose of model verification the mathematical models were programmed and tested using the engineering mathematical software, Mat Lab. The combined fuzzy logic and mathematical models prove to be a highly effective means of completing the cleaner production evaluation in minimal time and with minimal resources. A comparative case study was conducted at a local metal finishing company. The case study compares the input requirements and outputs from the traditional systems with the system proposed in this study. The traditional model requires 245 inputs whilst the model proposed in this study is based on 56 inputs. The data requirements for the model proposed in this study is obtained from a plant operator in less than one hour whilst previous models required high level expertise over a period of up to two weeks. The quality of outputs from the model proposed is found to be very comparable to previous models. The model is actually found to be superior to previous models with regards predicting operational variations, water usages, chemical usages and bath chemical evolution. The research has highlighted the potential to apply fuzzy-mathematical hybrid systems for cleaner production evaluation. The two limitations of the research were found to be the usage of a linear experimental design for model development and the availability of Mat Lab software for future application. These issues can be addressed as future work. It is recommended that a non-linear model be developed for the individual processes so as to obtain more detailed process models. / National Research Foundation, Water Research Commission and Durban University of Technology

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A thesis submitted in partial fulfillment of the academic requirements for the Degree of M-Tech in Chemical Engineering, Durban University of Technology Durban, 2008. / The waste generated by metal finishers is rated as the most toxic and harmful to the environment. Metal finishing wastewater consists of heavy metals, cyanides, acids and alkalis. Formal treatment of waste generated has not been of primary importance to metal finishers. It would be ideal to develop a generic model to assist finishers to predict the effectiveness of wastewater treatment. The model must be able to predict effectiveness of treatment based on a variety of equipment, chemicals and concentrations. / M

Take care how you place your moccasins upon the earth, step with care, for the faces of the future generations are looking upfrom the earth waitingfor their turnfor life - Lyoru, 1988 Increasing levels of pollution and the increase in demand for water and other resources by industry led to a number of policies and regulations being developed and revised in South Africa. According to the Constitution of the Republic of South Africa (Act 108 of 1996), everyone has the right to an environment that is not harmful to health or wellbeing. In order to have the environment protected and sustained for future use, it became necessary to move away from the traditional fragmented approach to pollution and waste management and focus on an integrated strategy aimed at achieving a balance between ecological sustainability and socioeconomic development. In the Durban Metropolitan Area (DMA) , the Durban Metropolitan Council (Metro) incorporated pollution prevention in their bylaws, which contained stringent discharge limits for heavy metal concentrations. This posed a potential problem for metal fmishers who were concerned about complying with these discharge standards. In addition, the metal finishing industry was considered to be a significant contributor to the pollution load in the DMA, and therefore needed to find suitable solutions to dealing with environmental problems, especially waste management. Waste minimisation was believed to be a good tool for this industry to utilise in order to reduce its pollution load. It was seen from the literature and case studies from international initiatives that waste minimisation results in an improvement in process efficiency and reductions in production costs and environmental impacts, generally at minimal costs. A waste minimisation club was initiated for the metal finishing industry in the DMA in June 1998. The club consisted of twenty-nine members of which the majority were small and medium sized companies. The club was run over a period of thirty months. A core group of sixteen companies actively participated in the activities of the club. During the period of investigation, a total of 391 waste minimisation options were identified for club members and 147 of these options were implemented. This resulted in a total financial saving in excess of R 4 million for the duration of the club's existence. The saving represents combined savings in water, chemicals, metals, energy, effluent treatment, and waste disposal. Corresponding environmental benefits were achieved including a reduced demand for water, reduced toxicity of effluent from chemical and metal reduction, and a reduction in energy requirements. Four companies were investigated in detail and presented as case studies. These companies showed that the payback on implementing waste minimisation options was mostly immediate. The size of the companies was not critical in determining the level of success from running waste minimisation programmes. Success depended mainly on commitment from companies and motivation of project champions. It was found that the greatest barriers to implementing waste minimisation, as identified by companies, were a lack of time, resources, and commitment. Companies joined the club mainly for benefit of reducing costs and complying with legal standards. Aside from successfully raising awareness and promoting the concept of waste minimisation, the waste minimisation club also resulted in an improvement in the relationship between the metal finishing industry and the Metro, and among club members. Based on the results achieved by club members, and from managing the club, it was evident that the club was effective in promoting waste minimisation in industry. For the future running of clubs, it is recommended that waste minimisation assessment training be given to all employees of a company. It would also be more useful if companies reported savings on a more regular basis and more formally. In addition it is recommended that club membership should be limited to between ten and fifteen companies to facilitate improved management of the club. / Thesis (M.Sc.Eng.)-University of Natal,Durban, 2002.

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.

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

A local company instituted a new chemical procedure in their spray phosphating system used in the pretreatment of large components for industrial racking systems. An inorganic conversion coating is deposited on the workpiece surface during phosphating and this prepares the surface to receive an organic top-coat. The organic coating is applied to the workpiece surface in the form of a powder and cured to form a continuous film about 80 u.m thick. The solution chemistry of the phosphating system was monitored by sampling and chemical analysis and taking direct reading instrumental measurements on the process and rinse solutions. The process was also evaluated using the results of a waste minimisation audit. This involved gathering data on composition, flow rates and costs of inputs and outputs of the process. Two types of information were collected and used during the audit, namely chemical monitoring (concentration levels of Na, Fe, Zn, Mo, Mn and Cr and measurements of conductivity, TDS, SS and pH) and water usage data on the Phosphating Line and existing data (raw materials, workpieces and utility inputs as well as domestic waste, factory waste and scrap metal outputs). 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. The Mass Balance and the True Cost of Waste findings were obtained through more detailed calculations using the results of the chemical analysis. The results of the audit showed that the most important area for waste minimsation in the Phosphating Line was the (dragged-out phosphating chemicals present in) wastewater stream. According to the scoping audit, water usage had the third highest waste minimisation potential behind powder and steel consumption for the entire powder coating process. While the scoping audit and the specific water intake value showed that water consumption for the process was not excessive, it did not indicate that the pollution level in the rinse waters was high. Further, drag-out calculations showed that drag-out volumes were typical of those found in the metal finishing industry. However the presence of high levels of metal species in the rinse waters was highlighted through the chemical monitoring of the Phosphating Line. The True Cost of Waste Analysis estimated potential financial savings for the effluent stream at about R8000 for a period of 105 days. However this does not take into consideration the cost of the liability associated with this stream when exceeding effluent discharge limits (given in the Trade Effluent Bylaws) or of the chemical treatment necessary to render this stream suitable for discharge to sewer. Intervention using only "low-cost-no-cost" waste minimisation measures was recommended as a first step before contemplating further areas for technical or economic feasibility studies. However, a further study involving monitoring the sludge was recommended in order to establish the potential financial savings offered by this waste stream. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.

This study involved an assessment of the Pietermaritzburg Waste Minimisation Club (PWMC) during 2001, and a waste minimisation audit conducted at two coil coating lines. Waste minimisation is the reduction or elimination of waste at source4 • It is often achieved through waste minimisation clubs which comprise a small number of companies, generally in the same geographicaI area, that are interested in reducing waste 1"711 . The success of the PMWC was evaluated in terms of the degree to which members implemented waste minimisation principles. Two questionnaires were used to assess the success of the club. These indicated that although the training material gave the members a good understanding of the basic principles of waste minimisation, the material has not given the members enough practical information to implement a waste minimisation programme in their companies. The main barriers to waste minimisation identified include production pressure, operational constraints, lack of human resources and a lack of management time. The drivers for waste minimisation were financial savings, improved plant utilisation and improved environmental performance. Coil coating is a continuous process where a coiled sheet of aluminium is cleaned, pretreated and coated with paint. The flow rates, compositions and costs of all input and output streams to the cleaning and pretreatment sections were gathered from operators or measured. The data were collected over a three-month period to obtain a representative sample, and then analysed to determine waste minimisation opportunities using mass balances, monitoring and targeting, a scoping audit and a true cost of waste assessment. The scoping audit was found to be the most useful technique because it accurately prioritised the waste minimisation opportunities but required a relatively small amount of data for its application. However, the scoping audit underestimated the savings that could be achieved at the coil coating department and therefore the 'scope to save' percentages, which were developed for United Kingdom industries, need modification to better reflect South African industry. Opportunities for waste minimisation on Coil Coating Line 1 (CCL1) included reducing the water consumption, reducing the acid and chromium raw materials consumption, and finding a cheaper energy source for heating the process and rinse tanks. Potential fmancial savings of R116 000 and environmental savings of 18 200 kL of water or effluent per year were calculated for CCL1. The chromium and acid effluent treatment and solid waste disposal are the main areas for waste minimisation on Coil Coating Line 2 (CCL2). Savings could be achieved in these areas by using roller application ofthe chromium pretreatment rather than spray application, and by preventing a leak of chromium pretreatment into the acid process and rinse tanks. Other savings can also be achieved by operating the chromium process tank as a fed-batch process, and operating the alkali and acid process tanks as continuous processes at the specified chemical concentrations and with recycle of the rinse water (dragout). The total financial savings that can be achieved on CCL2 are R5.3 million, and potential environmental savings are 31 600 kL ofeffluent per year. / Thesis (M.Sc.)- University of Natal, Pietermaritzburg, 2002.