Theses and dissertations (Applied Sciences)
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Item Isolation and characterization of Bacillus spp. for use in the remediation of petroleum waste residues(2020) Masika, Wendy Snoyolo; Kudanga, Tukayi; Santosh, Ramchuran; Moonsamy, GhaneshreePetroleum hydrocarbons are toxic to all forms of life; therefore, environmental pollution caused by petroleum is of great concern. Environmentally friendly strategies are required for the remediation of the contaminated sites. Microbial populations comprising of several different genera have been detected in soil and water environments that have been contaminated with petroleum. This suggests that these organisms are able to use hydrocarbon compounds as a substrate for survival and could be harnessed in bioremediation of contaminated sites. The first stage of this research was focussed on the isolation, purification, screening and selection of putative Bacillus spp from environmental samples. Samples were collected from different sites around the Gauteng province in South Africa. Samples from both soil and water were obtained from selected sites including environments that were contaminated by oil. Isolate selection was based on the growth rate of the isolates, the degree of sporulation and the rate of oil degradation. The identities of the potential isolates as well as their safety status were clarified in order to reduce possible risk to end users or the environment. Once suitable isolates were identified, those that possessed inherently strong biodegradation ability were assessed for their efficacy as well as compatibility to perform in a consortium. Various organism combinations were assessed and compared to the efficacy of individual isolates, in order to formulate a bioremediation consortium. Of the 115 isolates, the top performing isolates, identified as GPA 11.2, GPA 7.1, GPA 3.5, GPA 8.3 and GPB 4.4, were obtained from a car workshop in Midrand and a taxi rank in Silverton. GPA 8.3 and GPA 4.4 were, however, eliminated due to their low sporulation efficiency. The selected Bacillus isolates were identified using 16s rDNA sequencing and GPA 7.1 and GPA 11.2 were identified as B. subtilis, while GPA 3.5 was identified as B. methylotrophicus. These isolates were further assessed for enterotoxin production and the presence of anthrax virulent plasmids pX01 and pX02. After conducting the biosafety assays, the isolates were rendered safe for use. The bioremediation potential of the consortium was evaluated using industrial effluents that contained hydrocarbons. Degradation of hydrocarbons using all three consortiums (Gen 3.1, Gen 3.2, Gen 3.3) in the respective industrial effluents were determined by measuring the rate of degradation for each hydrocarbon compound using Gas Chromatography (GC). Results indicated that the bulk of the contaminants were removed during the first 48 hours; and removal (%) did not increase significantly after 72 hours. The total petroleum hydrocarbons (TPH) (C8-C28) removal rates from synthetic effluent after 48 hours of treatment using the Gen 2, Gen 3.1, Gen 3.2 and Gen 3.3 consortia were 0.8, 0.26, 0.07 and 0.58 mg.L-1.h-1, respectively. The TPH (C8- C28) removal rate from true effluents after 48 hours of treatment using the Gen 2 (benchmark), Gen 3.1, Gen 3.2 and Gen 3.3 consortia were 0.23, 0.25, 0.12 and 0.17 mg.L-1.h-1, respectively. The results showed that the best performing consortium was Gen 3.1.This study has demonstrated the potential application of Bacillus as bioremediation agents for the treatment of hydrocarbon-contaminated sites. This technology could potentially also be utilised for addressing the challenges of a wider range of different hydrocarbon effluents.Item Assessment of a biological nutrient removal process for the remediation of edible oil effluent(2002-05-10) Mkhize, Sandile Psychology; Bux, FaizalEutrophication is a natural process that is greatly aggravated by the action of man in the natural environment. Deterioration of South Africa's natural water resources results directly or indirectly from the discharge of industrial effluent rich in nutrient nitrogen and phosphorus. The South African edible oil refmeries generally discharge poor quality effluent which impacts negatively on the water resources and wastewater treatment installations. The main aim of this study was to assess the capacity of a laboratory scale effluent treatment process that will produce final effluent of acceptable quality with regards to organic load and phosphate concentration prior to its discharge into the municipal sewerage system. The study was conducted in three stages: wastewater characterization, treatability studies, and laboratory scale treatment investigations. After analysing various effluent parameters, treatability studies were conducted using an aerobic-anaerobic sequencing batch reactor with a total hydraulic retention time of 24 hours. The results showed an average of 75 % reduction of COD and more than 90 % removal of fats, oils and grease (FOG). Based on the results of effluent characterisation and treatability studies, a laboratory scale activated sludge effluent treatment process was designed and operated with two bioreactors (aerobic and anaerobic) in series. The system was operated for a period of one-month resulting in 70 % removal of COD and 4% reduction in phosphate (P04-P). After some structural and operational changes from the original design configuration, the system was the operated continuously for the duration of the study period. An optimum COD removal of 75 % and 107 mgll P04-P reduction was achieved during the last operational phase of the system. More than 95 % reduction in fats, oils and grease (FOG) had been achieved in both semi-continuously and continuously operated systems.b.7