Colour and organic removal of biologically treated coffee curing wastewater by electrochemical oxidation method

Article type: Research Article

Authors: Bejankiwar, Rajesh S. | Lokesh, K.S. | Gowda, T.P. Halappa

Affiliations: Department of Environmental Engineering, S. J. Collge of Engineering, Mysore-570023, Karnataka State, India

Abstract: The treatment of biologically treated wastewater of coffee-curing industry by the electrochemical oxidation using steel anode were investigated. Bench-scale experiments were conducted for activated sludge process on raw wastewater and the treated effluents were further treated by electrochemical oxidation method for its color and organic content removal. The efficiency of the process was determined in terms of removal percentage of COD, BOD and color during the course of reaction. Several operating parameters like time, pH and current density were examined to ascertain their effects on the treatment efficiency. Steel anode was found to be effective for the COD and color removal with anode efficiency of 0.118 kgCOD·h^{-1}·A^{-1}·m^{-2} and energy consumption 20.61 kWh·kg^{-1} of COD at pH 9. The decrease in pH from 9 to 3 found to increase the anode efficiency from 0.118 kgCOD·h^{-1}·A^{-1}·m^{-2} to 0.144 kWh·kg^{-1} of COD while decrease the energy consumption from 20.61 kWh·kg^{-1} of COD to 12.86 kWh·kg^{-1} of COD. The pH of 5 was considered an ideal from the present treatment process as it avoids the addition of chemicals for neutralization of treated effluents and also economical with respect to energy consumption. An empirical relation developed for relationship between applied current density and COD removal efficiency showed strong predictive capability with coefficient of determination of 96.5%.

Keywords: electrochemical oxidation, coffee-curing wastewater, steel anode, COD and color removal

Journal: Journal of Environmental Sciences, vol. 15, no. 3, pp. 323-327, 2003