Treatment of acid mine drainage using constructed wetland and UV/TiO₂ photocatalysis

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dc.contributor.advisor Aoyi, Ochieng
dc.contributor.author Seadira, Tumelo Wordsworth Poloko
dc.date.accessioned 2017-05-23T01:14:06Z
dc.date.available 2017-05-23T01:14:06Z
dc.date.issued 2014-05
dc.identifier.uri http://hdl.handle.net/10352/346
dc.description M. Tech. (Chemical Engineering, Faculty of Engineering and Technology), Vaal University of Technology en_US
dc.description.abstract Acid mine drainage (AMD) is a serious problem associated with mining activities, and it has the potential to contaminate surface and ground water. The aim of this study was to evaluate the performance of constructed wetland and photocatalysis in treating AMD. Three identical unvegetated upflow constructed wetlands packed with natural zeolite (clinoptilolite) and coarse silica sand were made of a cylindrical plastic pipe, and the slurry photocatalyst was prepared using quartz material. A hydro-alcohol thermal method was used to prepare an anatase core-void-shell TiO2 photocatalyst. The results showed that the three unvegetated upflow constructed wetlands (CW) had relatively similar percentage removal of heavy metals despite their varying concentrations within the AMD. The removals were: Fe (86.54 - 90.4%); Cr (56.2 - 64.5%); Mg (56.2 - 67.88%); Ca (77.1 - 100%); and 100% removal was achieved for Be, Zn, Co, Ni, and Mn. The removal of sulphate was also 30%. Heavy metals concentration in CW packing material was significantly higher in the outlet of the constructed wetlands than in the inlet. The adsorption isotherms revealed that the experimental data fitted the Langmuir Isotherms better, which suggested a monolayer coverage of heavy metals on the surface of the adsorbents; thermodynamic studies showed that the nature of adsorption taking place was physical; the kinetics models showed that the adsorption was first order reaction. A higher photocatalytic reduction (62%) of Cr(VI) was obtained at pH 2, 30 mg/l Cr(VI) initial concentration, and three hours of irradiation time. It was also found that the presence of Fe(III) enhanced the reduction of Cr(VI). The core-void-shell TiO2 photocatalyst showed a better activity than the commercial P25 Degussa for the reduction of Cr(VI) to Cr(III). The kinetic studies showed that the reduction of Cr(VI) was first order reaction. Photocatalytic reduction of Cr(VI) in real AMD sample was achieved only for the Douglas North Discharge (DND) sample (68%), and the Fe(III) reduction was found to be 83%. Therefore it was concluded that the combination of constructed wetland and UV/ TiO2 photocatalysis employing anatase core-void-shell TiO2 as a photocatalyst has a potential to reduce the toxicity of Cr(VI)-laden acid mine drainage. en_US
dc.format.extent xi, 91 leaves: illustrations en_US
dc.language.iso en en_US
dc.subject Acid mine drainage en_US
dc.subject Constructed wetland en_US
dc.subject Photocatalysis en_US
dc.subject Natural zeolite en_US
dc.subject Silica sand en_US
dc.subject Hydro-alcolhol thermal method en_US
dc.subject.ddc 622.5 en_US
dc.subject.lcsh Acid mine drainage -- Purification en_US
dc.subject.lcsh Photocatalysis en_US
dc.title Treatment of acid mine drainage using constructed wetland and UV/TiO₂ photocatalysis en_US
dc.type Thesis en_US


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