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Effect of bidens pilosa L in sulfate removal from industrial wastewater in a hydroponic system

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dc.contributor.advisor Mthembu, M.S.
dc.contributor.author Mthembu, Qhamukile Nkosingiphile
dc.date.accessioned 2019-07-17T10:51:50Z
dc.date.available 2019-07-17T10:51:50Z
dc.date.issued 2018
dc.identifier.uri http://hdl.handle.net/10530/1759
dc.description This dissertation is submitted in complete fulfilment for the Degree of Masters (Microbiology) in the Department of Biochemistry and Microbiology, Faculty of Science and Agriculture at the University of Zululand, 2018. en_US
dc.description.abstract Water contamination from human activities such as discarding sulfate-rich wastes into natural water resources leads to the introduction of sulfate and other toxic substances like heavy metals. This poses as a threat to human health and the environment since consumption of sulfate concentration greater than 250 mg/l causes diarrhoea and dehydration. Accumulation of sulfate in water also leads to the death of aquatic species and when sulfur is produced from sulfate, it may react with oxygen in the atmosphere and form sulfur dioxide which causes acid rain when reacted with nitrogenous gases. Acid rain is detrimental to the environment. Ion exchange chromatography is currently used in sulfate removal but it is expensive and energy consuming. This has necessitated the development of an environmentally friendly, cost-effective, and simple wastewater technique for sulfate removal using wetland technologies. In order to remove sulfate from wastewater, two hydroponic systems were constructed, and the first one was cultivated with Bidens pilosa L and the other one was left unplanted (control section). Wastewater collected from Tendele Coal Mine was introduced into both sections and the initial sample was collected. After every 24 hours the samples were collected at different hydraulic retention time, for 2 weeks. In all samples physicochemical parameters were determined using a pH meter. Sulfate concentration was determined using sulfate test kits and a spectrophotometer. The qPCR was used to identify the microorganisms responsible for the removal of sulfate in the system. Sulfate removal in the planted section was higher than in the control section. It was 2.9%,4.9% after 24 hours 6.5%, 11% after 48 hours, 12%, 17% after 72 hours, 16.3%, 25.4% after 96 hours, 18.2%, 34.8% after 120 hours, 26.9%, 44.6% after 144 hours, 34.7%, 55.1% after 168 hours, 42%, 63.7% after 192 hours, 47.5%, 71.5% after 216 hours, 53.2%, 73.3% after 240 x hours, 54.7%, 74% after 264 hours and 56%, 76.3 % after 288 hours over 2 weeks in the control and planted sections respectively. Sulfate concentration in the macrophytes was found to be 110 mg/l before treatment, and 353 mg/l after treatment. There was a significant difference between sulfate removal in the planted and control section and also in macrophytes before and after treatment, indicated by p=0.0001. This indicated that the hydroponic system was able to remove sulfate from wastewater using the combination of the mechanisms of plant uptake and microbial degradation. Sulfate removal was also indicated by final concentration of sulfate, which was 169 mg/l in the planted section which was below the acceptable amounts of sulfate in water (by World Health Organization) while it was 309 mg/l in the control section. Temperature had a moderate negative correlation on sulfate removal (-0.38 ≤ r ≤-0.42) while COD had a very strong negative correlation (-0.94 ≤ r ≤-0.97). The dissolved oxygen indicated weak positive correlation (0.29≤ r ≤0.37), and pH indicated a strong positive correlation (0.80 ≤ r ≤0.79) in the planted and control section respectively. These correlations indicated that physical and chemical parameters were had an effect on sulfate removal. Microbial population of sulfate-reducing bacteria (Desulfobacter, Desulfovibrio) was present in both systems. Desulfococcus was present in the control section but absent in planted section due to its sensitiveness to oxygen. These findings shown that the hydroponic system had an ability to remove sulfate from industrial wastewater using macrophytes and sulfate reducing bacteria but the removal was dependent on physicochemical parameters. en_US
dc.description.sponsorship National Research Foundation en_US
dc.language.iso en en_US
dc.publisher University of Zululand en_US
dc.subject Bidens pilosa L en_US
dc.subject Industrial wastewater en_US
dc.subject hydroponic system en_US
dc.subject sulfate removal en_US
dc.title Effect of bidens pilosa L in sulfate removal from industrial wastewater in a hydroponic system en_US
dc.type Thesis en_US

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