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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
131

Intercomparacao de modelos matematicos de transporte de radionuclideos na geosfera

SHUKAIR, SHUKAIR M.S. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:41:01Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:58:01Z (GMT). No. of bitstreams: 1 03984.pdf: 4155430 bytes, checksum: 939d4f5a69f51c8028d8c59f56de0a8e (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
132

Optimisation of edible oil effluent degredation by microorganisms

Surujlal, Swastika January 2003 (has links)
Dissertation submitted in compliance with the requirements for the Masters Degree in Technology: Biotechnology, Durban Institute of Technology, 2003. / Water is a precious and very valuable resource. Water resource shortages are problems that are plaguing the world. There is therefore a high demand for tightening water quality standards for both potable water and waters in the environment. It is becoming a necessity to treat and reuse wastewaters, especially wastewaters from industries, as these waters are of concern due to their toxic effects on the environment. In South Africa one of the industries of major concern is that of the edible oil industry and there are over a dozen ofthese industries in South Africa alone. Each of these industries utilises approximately 1.75 million m3 of water and discharges approximately 0.61 million m3 to the sewer each year. This wastewater that is being released has very high organic, inorganic and fats, oils and greases loads. Depending on the type of refinery process conducted on the crude oil, the effluent quality and quantity varies on a day to day basis. The two types of refinery procedures are the physical refining, where water is used or chemical refining where caustic soda is used. The organic load ofthe untreated effluent can range from 1 100 to 8 990 mg COD/L, the oils and greases can range from 80 to 1 360 mg/L and the pH can range from 1.8 to 10.5. / M
133

Algal biotechnology and the beneficiation of saline effluent wastes

Rose, P D (Peter Dale) January 1992 (has links)
Saline deterioration in the South African public water system has been documented and disposal of brine wastes has been identified as part of the problem. The broad aim of this research programme was to undertake an initial technical study to evaluate the feasibility of integrating algal biotechnology into a disposal function for these wastes. A demonstration of utility in the form of products and waste treatment could produce a beneficiation of saline effluents and provide incentives necessary to deal with the disposal issue. The study attempted to demonstrate a synthesis between the two main thrusts in algal biotechnology that have produced large-scale practical applications - stable, predictable algal production in saline media and the cost effective High Rate Oxidation Ponding (HROP) process for incorporating algal production into a waste treatment function. Tannery organic saline effluents and the biotechnology of Dunaliella salina culture producing β- carotene were chosen as paradigms for the study. 1. The alga was shown to grow in certain tannery effluents producing enhanced biomass yields compared to defined inorganic medium cultivation. The potential for amino acid or protein supplementation of defmed culture media was noted. 2. A reduction in organic load simultaneous with the growth of D.salina was recorded in laboratory-scale simulations of the HROP process. Rates similar to the fresh water HROP equivalent were demonstrated. 3. These results suggested the uptake and storage of organic nitrogen by D.salina. The consequent inhibition of β-carotene accumulation by the organism presented a potentially insurmountable obstacle to the feasibility of β-carotene production in this medium. Uptake and release of organic compounds, previously demonstrated in phytoplankton and other micro-algae, was confirmed in this study for D.salina. The evidence acquired indicated the internalization of both glycine and bovine serum albumin. An ultrastructural study demonstrated mechanisms by which this process might occur. 4. The release of substantial quantities of glycerol was shown. A mechanism whereby D. salina may use this to regulate ammonia availability via control of its associated bacterial population was observed. Glycerol release was identified as presenting an application in treating refractory organic wastes, such as secondary sewage sludges, by elevating C:N ratios. This could demonstrate a significant utility for brine waste impoundments. 5. A multistage production process was proposed to deal with the problem of β-carotene inhibition by separation of the growth and metabolite accumulation functions into separate unit operations. It was shown in this study that the stress of nitrogen deficiency combined with high salinity provides for effectiveβ-carotene accumulation under the conditions of low illumination that pertain in dense cultures. Subjected to these conditions effluent-grown cells show delayed but unimpaired {j-carotene accumulation. 6. A role for the plant hormone abscisic acid in mediating the stress response was demonstrated in D.salina. Fluorescence induction studies suggested the presence of a signalling process forming part of a sensitivity control mechanism. Stress induction of β-carotene accumulation could occur through four clearly defined stages. Potential was identified for using this response as a physiological probe for monitoring and regulating the stress induction process. 7. The multistage processing concept requires effective algal cell separation technology. The use of cross-flow ultrafiltration and diafiltration with a polyethersulfone tubular membrane system was demonstrated as an effective process for the recovery and washing of D. salina. Cell concentrates were produced in a viable form. 8. Process designs incorporating the findings of the research programme are presented demonstrating how effluent and organic waste treatment functions may be combined with the production of D.salina and its products. Application of the multi-stage processing concept to β-carotene production in a defined medium process was identified as offering a potential four-fold yield enhancement. This could have a significant impact on a high cost, marginal algal biotechnology process. Aspects of novelty have been claimed in provisional patents applications. A provisional demonstration of the feasibility of D.salina production in tannery effluent indicates that algal biotechnology may provide a utility for, and hence the beneficiation of saline effluent wastes.
134

Petroleum waste disposal challenges in selected African countries - policy, practice and prospects

Vrede, Bruce January 2014 (has links)
Magister Artium - MA / The oil industry is growing increasingly aware of its serious image problem. There is a growing awareness of the systematic abuses of people and the environment inherent in the production, processing and marketing of petroleum. (Rowell, 1997). From the Club of Rome to the Bruntland Report to Rio De Janeiro and Johannesburg Earth Summits, increased pressure on the oil industry has been witnessed. Pressure has mounted to, in particular, start managing the industry’s impact on the environment. It was the first pictures of earth from space, which revealed the view of the limited “spaceship earth”, after which Garrett Hardin’s seminal article, entitled ‘The Tragedy of the Commons’ triggered an understanding of the close links between the environment and our economic activity in 1974, Daniel Yergin (1991) argues. Today the oil industry is facing ‘peak oil’ (the point in time when the maximum rate of petroleum extraction will be reached) and the looming fallout from environmental damage costs and disasters (Clyde,1996). It has been argued by Brain Clyde (1996) that the emergence of notions of ‘sustainable development’ and practice in the context of the oil industry, reifies global capitalism as the liberating and protecting force (Clyde, 1996). This thesis sets out to explore these notions of sustainable development and the ways in which they challenge (or not) the foundations of knowledge around environmentally ethical behaviour amongst large oil companies and the manner in which they manage, in particular, used oil. There is a growing body of research contained in the fields of Political Ecology and Industrial Ecology that points to the need for blame to be placed between multinational oil companies and national governments for failing in their mandate to protect the environment (Africa Institute, 2013 and Danida, 2012). This thesis argues that used oil management is not only the responsibility of oil companies but also that of national governments and suppliers in the general public. If the role of national governments is to create enabling conditions for the development of “fit for purpose” waste policy and regulations in order to lead or track “best practices” in used oil management, this thesis shows that more often than not, policy has either failed in practice or has not been developed owing to a lack of political will. The prospects for implementation of best practices typically speak to concepts of recycling, reuse and proper disposal in terms of Lansink’s Ladder (1979) concept (He was a Dutch member of parliament who presented a schematic presentation of the order of preference for waste management options, with disposal at the bottom and prevention at the top) of the “waste hierarchy” with which this study engages (Gertsakis and Lewis, 2003). The waste management hierarchy supports the approaches taken in studies in the field of Industrial Ecology which suggest practice-based solutions to waste oil and policy development. This thesis explores four contexts of waste management in Africa, focusing on comparisons between policy and practice in sites that I have worked at in Kenya, Mozambique, Namibia and relates these to South Africa. Waste management infrastructure to support used oil management is largely in poor shape or non-existent, whilst the gap between waste management policy and legislation and actual waste management practices appears to be widening. This is mainly due to ongoing capacity constraints or non-existence of waste management facilities for the different waste streams. As result of industrialization, urbanization and modernization of agriculture in Africa waste generation is expected to increase significantly. My interest in this research, and the major intention of this study came from my personal experience working as an environmental specialist in the petroleum industry, where I have witnessed poor waste oil practices as a result of inadequate infrastructural or waste disposal options. Exacerbating the problem, as I argue in the study, are poorly defined waste management policy/regulations with consequential severe environmental and health degradation.
135

The biotechnology of high rate algal ponding systems in the treatment of saline tannery wastewaters

Dunn, Kevin Matthew January 1998 (has links)
Salinisation has been identified as a major cause of the progressive deterioration in the public water system in South Africa. To deal with this problem Waste Stabilisation Ponding systems have been used by the Leather Processing Industry as zero-dischaJ;ge wastewater evaporation disposal processes in water-limited inland regions of the country. While effective in the evaporation disposal function these systems are plagued by the generation of serious odour nuisance creating intractable environmental problems relating to adjacent residential communities. High loading to ponds of organic compounds, sulphides and ammonia results in strongly reducing anaerobic conditions prevailing in early parts of pond cascades. These are characterised by bright red colours due to the predominance of purple photosynthetic bacteria. Sporadic micro algal blooms of Spirulina sp. and Dunaliella sp. had been previously noted to occur on the latter ponds in these cascades, and were associated with their conversion to facultative function, with aerobic surface layers, and a marked reduction in odour release. This research programme undertook an investigation of the microbial ecology of a tannery waste stabilisation ponding system to describe factors which give rise to these blooms, and to determine whether microalgal growth may be manipulated to achieve a reliable oxygengenerating capping of the anaerobic ponds. The predominance of near pure cultures of Spin/lina platensis was demonstrated for the blooms and factors restricting its growth in the system were described. These include the interaction of ammonia and sulphide toxic effects and laboratory studies were undertaken to show how effluent loading may be regulated to enable effective growth of the cyanobacterium. At appropriate dilutions of tannery effluent an enhancement of growth was noted, compared to growth in defined mineral medium. An investigation of this phenomenon provided preliminary evidence for organic uptake by the pond micro algae and a possible contribution to heterotrophic nutrition. The manipulation of Spirulina sp. growth in a High Rate Algal Pond raceway was undertaken in outdoor pilot plant studies and the effect of microalgal capping of the anaerobic ponds in the cascade was demonstrated by activating a recycle loop from a blooming facultative pond. Heavy metal contaminants were effectively eliminated by an optimisation of the primary anaerobic pond function and precipitation as metal sulphides. Biomass was harvested and dried, during which a range of methods were evaluated. Toxicological studies were undertaken on the dried biomass using Artemia and chick assays, and feed studies showed its useful application in rations for the abalone Haliotlls midae and rainbow trout Onchorhynchlls mykiss. Based on positive independent assessment of research outcomes, a decision was made by the tanning company operating the Waste Stabilisation Ponding system, to proceed to the construction of a full-scale 2 500 m2 High Rate Algal Pond raceway. This would be used for controlled Spirlilina biomass production to effect a practical capping of the anaerobic ponds in the system, and to evaluate its commercial potential in the feed market. The Advanced Integrated Wastewater Ponding System described by Oswald (1991) provided the conceptual basis for the Algal Biotechnology process development undertaken. The studies of the microbial ecology and the biotechnological potential of this system have shown that a Spirulina-based High Rate Algal Ponding process can be engineered in such a way that saline tannery effluents may be treated to effect a significant reduction in overall pollution load, that biomass may be recovered as a value added product of the treatment process and that the operational performance of Waste Stabilisation Ponding systems, and hence their immediate environment, may be improved by the use of the High Rate Algal Pond as a retrofitted upgrading unit operation.
136

A process for the detanning of chrome leather wastes utilising tannery effluents

Glaum, Deanne Melanie January 1994 (has links)
The considerable volume of chromium-bearing wastes generated during the process of leather tanning, exacerbated by the potential for trivalent chromium in the wastes to be oxidised to the toxic hexavalent state, has created a major waste disposal dilemma for the tanning industry. While methods are available for the safe and effective treatment of residual chrome-tanning liquors, little has been done to address the issue of the chrome-bearing solid wastes. Given the increasingly stringent environmental compliance standards facing tanneries, unless an appropriate treatment process is developed in the immediate future, the continued use of chromium as a tanning agent could be compromised. Recent investigations have demonstrated the potential of heated alkaline conditions for dechroming these solid wastes. This study expanded upon these considerations and examined the feasibility of utilising the highly alkaline tannery waste effluents as cost-effective, substitute alkaline media. The three effluents considered in this study, classed as lime sulphide liquors, were shown to be capable of dechroming wet blue shavings, with resultant separation of the solid wastes into a protein and a concentrated chromium product. The solubilised protein product contained low chromium concentrations which comply with legal discharge limits. The precipitated chromium product offers opportunity for reutilisation in the tannery. A novel industrial-scale treatment process, based on these investigations, indicated the process to be capable of treating the quantity of shavings produced on a daily basis by a medium to large scale tannery. Application of this method for the dechroming of other chrome-tanned solid wastes was also shown to be feasible.
137

The development of a marketing strategy for a tannery waste by-product

Mkhonta, Mpendulo Colin January 2010 (has links)
Worldwide chromium waste from tanneries is a major environmental concern. A considerable amount of effort is being implemented by tanneries to resolve the environmental concerns. Because of the wide range of chemicals used in tanning, waste treatment is an important issue in the industry. All the tanneries put considerable money and effort into treating their effluent. South African tanneries currently have various methods of disposing of their chrome waste. Most have systems for recycling the waste and disposing of it in municipal waste dumps or it is dumped on the company's own land. Hence the cost of disposal varies widely. Some companies are forced to pay excessive amounts to dispose of their waste at hazardous waste dumps. Others appear to get away by using municipal dumps. Trivalent Chrome (Pty) Ltd offers a solution to the environmental concern by extracting the most dangerous compound in the waste and converting it to a by-product (green chrome oxide). However, the company must be able to then sell of the green chromium oxide. The study seeks to address how the company can market the by-product.
138

Simulation of fluid flow in fractured rock : a probabilistic approach

Samaniego, Jose Antonio January 1985 (has links)
No description available.
139

The use of wetlands as a wastewater treatment technique: a literature review

Fillmore, Gary Boyd 26 January 2010 (has links)
<p>As the database of information for constructed wetlands grows, the benefits and limitations of this alternate wastewater treatment technology will be better understood. Based upon the results for numerous field and case studies, wetlands treatment can be highly successful at a relatively low cost. This technology appears to hold considerable promise for its technological capabilities plus it is widely applicable. Wetlands treatment has been successfully used to treat domestic wastewater, industrial wastewater, leachate, acid mine drainage and stormwater.</p> / Master of Science
140

A systems view of the nuclear waste dilemma

Bonnett, Timothy Charles 20 January 2010 (has links)
The nuclear waste problem is defined and analyzed from a systems engineering viewpoint. Problem magnitude and systems context are discussed. Requirements for a waste repository are presented and the current progress of the repository is noted. The Department of Energy's waste disposal system including repository site selection, monitored retrievable storage facility, and waste transportation system is analyzed. A description of nuclear fuel reprocessing is given. The potential benefits and risks of reprocessing are addressed including economic feasibility and environmental issues. A framework for systems analysis of the problem is presented. Four recommendations for further systems analysis are presented: 1. An unbiased systems analysis of the Yucca Mountain proposed repository including indirect political, social and economic aspects. 2. A systems engineering backing of the monitored retrievable storage facility 3. Development of rail transportation guidelines for nuclear waste 4. An economic analysis of the feasibility of spent fuel reprocessing to include indirect costs / Master of Engineering

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