Dissertation (M.Sc. (Chemical engineering)) -- University of Pretoria, 2008. / Includes bibliographical references (p. 42-52)

Thesis (M.A.)--Memorial University of Newfoundland, 1999. / Bibliography: leaves 140-147.

Thesis (M. S.)--Economics, Georgia Institute of Technology, 2006. / Haizheng Li, Committee Chair ; Patrick McCarthy, Committee Member ; Vivek Ghosal, Committee Member. Includes bibliographical references.

Master of Science

no abstract provided by author / Master of Science

M.S.

In nearly all chemical industries the problem of wastes is one of importance, and in any scientific study of waste disposal, the concept of the B.O.D. of the waste is vital. The B.O.D. is usually measured by an arbitrary standard test procedure, but may be determined by manometric measurement of the free oxygen utilized. In either case, the B.O.D. determination requires at least 24 hours. Since the free oxygen involved in the B.O.D. of a waste is utilized in metabolic processes of various microorganisms present, an increase in the number of microorganisms lowers the time required for oxidation of the wastes. In this investigation, the B.O.D. of several wastes was determined by measuring the change in the oxygen uptake of high concentrations of microorganisms because of the presence of the waste. These determinations involved a modification of the resting cell technic used in conjunction with direct Warburg technics. High concentrations of washed cells were prepared and small amounts of the waste added. A control was prepared with distilled water. The effects of waste concentration, bacterial concentration, and temperature were studied. The wastes studied included raw sewage, blowdown liquor and total mill wastes from a semichemical pulp mill, and effluent from an anaerobic, sewage-blowdown liquor digester. The concentrations of microorganisms used ranged from 3.4 to 17.0 milligrams of dry bacterial cells in a total volume of 2.5 milliliters of a 0.05 molar phosphate buffer at a pH of 6.8. The manometric B.O.D. was determined at 30°C. The manometric B.O.D. remained constant at 1,785 parts per million for 1:50 and 1:125 volumetric dilutions of the effluent. The manometric B.O.D. remained constant at 10,200 parts per million for volumetric dilutions ranging from 1:125 to 1:1000 for a sample of the blowdown liquor. The manometric B.O.D. of sewage, blowdown liquor, and mixtures of the two wastes was determined. The values obtained were compared with the standard five-day B.O.D. The manometric B.O.D. of the sewage and the blowdown liquor was 413 parts per million and 13,760 parts per million, respectively. The standard five-day B.O.D. of the sewage and the blowdown liquor was 495 parts per million and 37,800 parts per million, respectively. The manometric B.O.D. of 1:1 by volume mixture of the two wastes was 9,900 parts per million, while the standard five-day B.O.D. was 31,200 parts per million. / Master of Science

M.Sc. / The lower Thukela River catchment supports the highly industrialised Mandini/Sundumbili Industrial Complex, which in turn supports Tugela Rail, a textile factory, a vegetable-oil factory, as well as the Sundumbili Sewerage Treatment works. All of these industries release their wastes into the Mandini River that leads into the lower Thukela River. Another major potential impacting factor on the lower Thukela River is the Sappi Tugela pulp and paper mill that has both abstraction and discharge points in the same region. In 2004 the Department of Water Affairs and Forestry completed a comprehensive Reserve Determination study for the Thukela River. Upon reviewing the results it was clear that many of the variables assessed were of low confidence or there was not sufficient data collected within the region of the Mandini and Thukela River confluence and further downstream (Resource Unit K). Therefore the previous studies were not able to determine the degree to which the industries in the lower Thukela system impacted upon the integrity of the system. The aim of this study was therefore to assess the contributing impacts of the Tugela pulp and paper mill and other industrial activities on the ecological integrity of the lower Thukela River. This was done by through a toxicity assessment of the potential impacts of effluent and wastewater using the Direct Estimation of Ecological Effect Potential (DEEEP) methodologies. The toxicity of pulp and paper effluent from the Thukela mill and the receiving water body was compared to effluents from two other mills (Stanger and Ngodwana), assessing the water quality in relation to the input of different industrial effluents in the lower Thukela River. The general integrity of the lower Thukela River in relation to the input of different industrial effluents was assessed using the Habitat Quality Index (HQI), Habitat Assessment Index (HAI), macroinvertebrate and fish population studies. These studies were integrated to derive the Ecostatus of the lower Thukela River using the Macro-invertebrate and Fish Response Assessment Indices (MIRAI and FAII respectively). The toxicity testing (DEEEP) showed the paper mill effluent in the Mandini River was the least hazardous whilst Ngodwana effluent showed the highest potential to elicit a harmful impact on the receiving water body. The latter effluent displayed the highest LC50 values for the fish and the Daphnia toxicity tests, as well as an extremely high base-pair substitution mutagen activity. Toxicity was also found in algae at 100% raw effluent exposure. Tugela and Stanger mill effluent samples were very similar in their toxicity, except that Stanger effluent showed greater mutagenicity potential with exceptionally high values of revertants. The Tugela effluent samples showed no concerning levels of mutagenicity. The fish showed lower levels of response to the Tugela sample when compared to the Stanger sample. Thus comparatively the Thukela system is regarded to be the least at risk with regards to effluent discharge into the receiving water body. The lower Thukela River integrity assessment showed a sharp increase in temperature below the discharge point of the pulp and paper mill effluent. This was attributed to the excessive temperatures recorded in the pulp and paper effluent itself. There was further decrease in dissolved oxygen, which was due a combination of the industrial waste water in the Mandini River and the pulp and paper effluent. The increased organic content in the sediments of the lowest site situated downstream (TR5) is a combination of both reduced velocity of the stream flow entering the upper reaches of the estuary as well as increased organic material entering the river via the pulp and paper effluent and the Mandini River above TR3-D. This was accompanied by increased contribution of fine particle size sediments to the overall sediment composition. Habitat conditions were near natural at sites upstream of the Mandini River and effluent discharge confluences with the Thukela River. The exception was at TR1 as the weir results in unnatural inundation of biotopes upstream. The habitat conditions around the confluences of the Mandini River and pulp and paper mill effluent discharge are diminished with a recovery noted further downstream at TR4 and TR5. Invertebrate assessment shows the upstream sites to be natural, while the impact sites were largely to seriously modified. Once again the downstream sites (TR4 and TR5) show an improvement to recover to a moderately modified state. The fish assessment also shows a decrease in the FAII score below the impacts when compared to the integrity above the impacts. However these results are of low confidence due to insufficient sampling effort as only electronarcosis, seine and cast nets were used. The Ecoclassification assessment indicated a clear decrease in Ecostatus between the sites that are upstream of the impacts caused by the industrial effluent from the Mandini River and the pulp and paper mill effluent from the effluent discharge stream. The MIRAI also clearly indicated that the major impacts are caused by the combination of the Mandini River and the pulp and paper effluent. However there was a recovery in the river further downstream from the impacts.

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