abstract / Biological Sciences / Doctoral / Doctor of Philosophy

M.Tech.Chemical Engineering. / The distillery wastewaters released from industries that use molasses as a major source of carbon in their fermentation processes pose serious threats to the water quality in several regions around the globe. Melanoidin is an antioxidant that results from the Malliard reaction found in fermentation and distillation processes. This study explores the removal of melanoidin from aqueous solution using natural clinoptilolite modified using cationic surfactant hexadecyltrimethyl ammonium bromide. The absorbent media was characterized using analyatical techniques such as BET, FTIR, SEM-EDS and XRD analysis. Given the relatively low cost of natural zeolite, it is possible to apply the sorbent in polishing distillery wastewater after a biological process. Since both natural zeolites and distillery waste streams are used in agriculture, a prudent way to dispose the spent media is to use it as fertilizer in farming.

Thesis (MTech. degree in Environmental management.)-Tshwane University of Technology, 2008. / Aims to generate information on the quality of water from boreholes and the Steelpoort river in order to ascertain the level of pollution within the vicinity of Vantech mine. The information is envisaged to help a better water management within the area. The following objectives were pursued: to measure water quality parameters ; to investigate the extent of the pollution plume movement ; to study the composition and geological factors in the area in relation to mobility of groundwater and to determine the impacts of Geo hydrological characteristics.

The focus of this work was to develop a general methodology for modeling water quality in coastal waterbodies. The methods were developed in the context of modeling bacterial total maximum daily loads (TMDLs), but the general approach is applicable to a wide variety of pollutants. The study area for this dissertation was the Copano Bay watershed, which is located on the Texas Gulf Coast. The developed approach combines simple modeling techniques, of the type recommended by state and national advisory groups, in a GIS (geographic information system) framework, resulting in a methodical, easily transferred approach. This work addresses coastal systems where water quality is a function of operations in non-tidal rivers, tidal rivers, and bays, combined with the effects of watershed contributions. An uncertainty analysis was done to quantify a subset of the variance in the modeled results. Outcomes from this work include modeling tools, a documented workflow for modeling water quality in coastal watersheds, procedures to quantify the uncertainty associated with the developed approach, insight to the factors affecting water quality in the study area, and mean annual bacterial TMDLs for the impaired waterbodies of the Copano Bay watershed. / text

published_or_final_version / abstract / toc / Civil Engineering / Master / Master of Philosophy

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Nitrate pollution of ground and surface water can stem from the mismanagement and over-application of both inorganic and organic fertilizers. This results in the occurrence of non-point externalities, which infringe on the overall level of social welfare. Market based environmental policies, known as economic instruments, can be developed to curb the level of this non-point externality. Such policies directly affect the management decisions of agricultural producers, providing them with incentives to change their management practices. The overall objective of this study is to analyze an array of economic instruments which could feasibly curb water quality degradation resulting from the over-application and misuse of manure and inorganic fertilizers in agricultural production. The economic instruments are compared in terms of their relative effectiveness in decreasing nitrate water pollution and social damage. This thesis develops a three agent manure market model, wherein a vegetable producer and composter can purchase manure from a dairy producer or inorganic fertilizer from an exogenous fertilizer market. The production activities of each agent are modelled using real world production data. A non-linear programming technique is used. The imposition of a percentage manure tax was found to alter the vegetable producer’s derived demand for manure, and resulted in less manure being exchanged between the dairy and vegetable producers. The provisions of a percentage manure composting subsidy increased the quantity of manure demanded by the composter and decreased the amount of manure consumed by the vegetable and dairy producers. The imposition of an inorganic fertilizer tax increased the demands for manure fertilizer, as did the manure application limit. The effects on social damage are dependent on the leaching and surface run-off susceptibilities of each operation’s associated land base. The composting subsidy appeared to be the most efficient instrument for decreasing the overall level of social damage, when qualitatively analyzed. It induced decreases in the demand for manure by both the dairy and vegetable producers, while increasing the demand for manure of the composter. This results in an overall social benefit. There must be, however, financial justification for the implementation of such an instrument.