The application of bioremediation: reduction of metal concentrations in river water and COD in distillery effluent

The major aim of this study was to evaluate and develop artificial bioremediation systems to reduce or remove metal pollutants from contaminated river water and to decrease the chemical oxygen demand (COD) in distillery effluent. Metals were extracted using the nitric acid digestion method, and the concentrations determined using inductively coupled plasma-atomic emission spectrometry. A decrease in metal concentrations was observed for most of the metals analysed in the river water after being pumped through the bioreactor system for approximately two weeks, e.g. Al concentration decreased from 0.75 mg.l⁻¹ to 0.18 mg.l⁻¹ and for Ni, from 0.19 mg.l⁻¹ to 0 mg.l⁻¹. In addition, the COD counts decreased from 2255 mg.l⁻¹ to a final value of < 150 mg.l⁻¹ in the distillery effluent. It could thus be concluded that the bioreactor system decreased the COD and metal concentrations in the distillery effluent as well as the river water, respectively. A bioreactor is being evaluated on-site at a wine cellar to reduce COD and will be constructed at a site along the Plankenbrug River.