Removal of ciprofloxacin from hospital wastewater using electrocoagulation technique by aluminum electrode: Optimization and modelling through response surface methodology

Pharmaceuticals as severe contaminants of surface and ground water around the manufacturing communities and residential zones received growing attention recently. Since, there is no report on ciprofloxacin (CIP) removal using electrocoagulation (EC) process by aluminum electrodes, the present work deals with efficient removal of CIP from hospital wastewater using mentioned method. Response surface methodology (RSM) was used to evaluate the main effects of parameters, their simultaneous interactions and quadratic effect to achieve the optimum condition for EC process. According to the obtained results from regression analysis, it was found that the experimental data are best fitted to the second-order polynomial model with coefficient of determination (R-2) value of 0.9086, adjust correlation coefficient (Adj. R-2) value of 0.8796 and predicted correlation coefficient (pred. R2) value of 0.7834. EC process was applied successfully with removal efficiency of 88.57% under optimal operating condition of pH 7.78, inter-electrode distance 1 cm, reaction time 20 min, current density 12.5 mA cm(-2) and electrolyte dose of 0.07 M NaCl with the initial CIP concentration of 32.5 mg L-1. The experimental efficiency was in satisfactory agreement with the predicted efficiency of 90.34%. The obtained results revealed that, sweep flocculation as a determinant mechanism controlled the adsorption of CIP molecules on aluminum hydroxide precipitates. Electrode consumption and electrical energy consumption were found to be 66.80 g m(-3) and 0.613 kWh m(-3), respectively. The obtained results from real sample analysis revealed that the initial CIP concentration of 1544 61,,g L-1 of hospital wastewater were found to reached to zero after applying optimal condition of EC process. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.