Please read the abstract in the front section of this document / Dissertation (MSc (Food Science))--University of Pretoria, 2005. / Food Science / unrestricted

Aerated stabilization basins (ASB), like many other biological treatment systems, demonstrate a temperature dependency. A decrease in treatment efficiency usually results from a decreasing basin temperature and has often been related to a decrease in the reaction rate coefficient, K. This relationship to the reaction rate may well apply for other treatment systems, but it has not been clearly demonstrated for aerated stabilization basins. This study develops data on steady-state performance at 3° C in order to present a coherent reference point for future ASB temperature studies and to define performance characteristics at 3°C. The following performance criteria were documented in the study: 1. Substrate removal in terms of filtered substrate removal. (61 - 80 per cent COD removal and 76 -98 per cent BOD₅ removal for retention times of 1 - 16 days). 2. System treatment efficiency defined in terms of gross effluent COD and BOD₅. (23 - 50 per cent COD removal and 18 - 80 per cent BOD₅ removal for retention times of 1 - 16 days). 3. Net biological solids production (0.25 lbs/lb BODu or COD used). 4. Oxygen utilization requirements (0.123 lbs O₂/ lb COD removed and 0.143 lbs O₂/BOD₅ removed for retention times of 2 - 16 days. Endogenous respiration - 0.75 mg/hr/ gm MLSS). 5. Nitrogen transformation. (A transformation of Kjeldahl nitrogen in the biological solids to NH₃ nitrogen in the filtrate was found apparently as a function of retention time). 6. Post Settling. (One day's aeration with one day settling was found to give equivalent treatment as eight days aeration and one day settling). Data was obtained at two loadings to provide information on the influence of influent concentration on overall performance. Established in the experiment was that any of the common mathematical models used to describe ASB operation, McKinney's, Eckenfelder's, or first-order exponential, could predict system treatment efficiency at 3°C for retention times beyond two to four days. It was further shown that only the Chemostat model would describe the substrate removal measured in the study. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

Each year the problem of where to dispose and how to dispose of commercial, domestic and industrial solid wastes becomes worse. The growth rate of solid wastes continues to expand both because of the per capita increase in solid waste produced and because of population growth. Traditional disposal techniques such as dumps and landfills are becoming more expensive to operate mainly because of the lack of suitable land and the increased competition to obtain it. The growing inability of established disposal systems to handle the expanding solid wastes, generates further impetus to find new disposal techniques. Ignored environmental effects, particularly the growing pollution of air, land and water are no longer as acceptable to an increasingly pollution conscious public. With the changes in community attitudes towards the preservation of natural assets, disposal techniques previously too expensive to compete with traditional disposal techniques now are becoming more acceptable. The purpose of this thesis is to examine whether the benefits of using a new grinding disposal technique outweigh costs. The community selected for the analysis was the District of North Vancouver, British Columbia, which forms part of the Greater Vancouver Metropolitan Area. Presently, the District of North Vancouver operates a controlled landfill disposal technique known as the Premier Street Landfill. Various forms of air, land and water pollution occur at or from the site. The present landfill disposal technique is economically efficient with disposal costs of about $1.00 per ton of solid waste disposed. A benefit-cost analysis was conducted using the present landfill disposal technique as the control situation and the grinding disposal technique as the possible alternative. The point of view of the analysis was that of the Corporation of the District of North Vancouver which would be the decision making authority. For comparison purposes, different volume capacities were used in the analysis. The district's borrowing rate of 7% was used as the discount rate. Rates above and below the selected discount rate were also used in the analysis for comparison purposes. The value of net intangible benefits was also calculated to show what value would have to be placed on these benefits by the District of North Vancouver to justify the use of the disposal techniques involved in the analysis which were not as economically efficient. The results of the benefit-cost analysis showed that the present controlled landfill technique is economically more efficient than the proposed grinding disposal technique. The District of North Vancouver would consequently not be justified in converting to a grinding disposal technique under present conditions, unless the value of the net intangible benefits was accepted as a legitimate monetary expense. / Applied Science, Faculty of / Community and Regional Planning (SCARP), School of / Graduate

This research examines the use of microcomputer-based expert systems as a diagnostic tool and an operational aid of conventional secondary wastewater treatment facilities. The research has shown that rule-based systems are well suited for the domain of wastewater treatment facilities operations using observational information. Advances in expert systems software combined with increased microcomputer processing power have made this development work possible with personal computers. These systems possess the capability to provide fully automated diagnostics and process control as well as acting as a teaching and development tool for operators in full-scale treatment facilities. The thesis describes the technical aspects of wastewater treatment as applied to the development of a finished knowledge base system called WASTES (WAStewater Treatment Expert System). The thesis also discusses the development of the knowledge bases from their sources to implementation in the system. Recommendations and conclusions are also presented along with potential areas for further research. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

In view of very high toxicity potential of some heavy metals to aquatic life, there is a need for critical evaluation of known methods and development of new methods for purifying water and waste-water containing heavy metals. In this study, batch tests were performed to evaluate the relative efficiencies of six British Columbia coals in removing heavy metals (copper, lead, mercury and zinc) from water. On the basis of batch test data obtained, the best two coals, Kaiser Coal-Stock Pile Refuse and Kaiser Coal-Special Plant Feed, were tested on a continuous flow laboratory scale. The emphasis was placed on metal concentrations of 2 mg/1 and less for copper, lead and zinc and 5 vg/1 for mercury. The effects of adsorbate concentration, flow rate through the column (contact time), and pH of the solution on the adsorptive capacity of coal were investigated. A solution containing 0.5 mg/1 of each of copper, lead and zinc was tested to investigate the ability of the coal to remove metals from a mixture of many metals. The adsorptive capacity of the best two coals was also compared with some commercially available adsorbents. On the basis of capacity and rate of adsorption, Kaiser Coal-Stock Pile Refuse was found to be the best of the six coals tested. For the specific testing conditions in this investigation, the better metal-removing efficiency of coal as compared with activated carbon and nitrohumic acid indicate that the coal may be a feasible alternate to purify effluents containing heavy metals / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

MSc., Faculty of Science, University of the Witwatersrand, 2011 / A survey was carried out on small and micro enterprises in the Braamfontein region of Johannesburg, to determine the aggregate compositions of solid waste materials generated and collected for recycling purposes, and to determine the attitude(s) and perception(s) of manager(s) and owner(s) of such enterprises, to the collection of solid their waste(s) for recycling purposes. A stratification method based on staff numbers was used to select 60 random samples of small and micro enterprises. Results reveal that 62% of these businesses were not collecting their solid wastes for recycling purposes, despite a high daily occurrence of recyclable (paper: 95%, plastic: 72% and organic: 68%) wastes in their daily waste streams. Low levels of collection by businesses were attributed to ‘time-factor’ issue in the collection of their recyclable wastes, while the provision of more recycling facilities in the area could improve their participation. Waste to landfill transportation trends in Johannesburg’s landfills were analyzed, as a measure of the waste problem in Johannesburg. Results suggest about 18% reductions in recycling waste materials transported to the various landfill sites in the city, from 2004 to 2008, and a 14% increase in other categories of general solid wastes for the same period. Despite the reductions in recycling waste materials recorded, the city recorded low levels of waste recovery practices for recycling purposes, particularly in small and micro scale commercial sectors. In achieving the City of Johannesburg’s wastes reduction goals, particularly the waste reduction targets set in the Polokwane Declaration, of reducing the amount of wastes disposed of by 50%, achieving a 25% reduction in disposable wastes by 2012 and to developing a zero waste plan by 2022 (City of Johannesburg, 2008), the municipality needs to play a pivotal role by providing needed recycling infrastructures, educating the society on the need for sustainable waste management and providing waste collection and management incentives.

No description available.

No description available.

The comparison of alternative systems of disposing efficiently and effectively of four to five pounds of solid waste per person per day in the United States urban communities is undertaken by using Kazanowski's standardized cost -effectiveness methodology. The economic criteria for studying this problem are often limited to cost or marketable measures; in contrast, use of a cost -effectiveness approach allows the inclusion of non- quantifiable measures of effectiveness such as public acceptance, politics, health risks, environmental considerations, and soil benefits. Data from a case study in Tucson, Arizona, is used to illustrate the problem.

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