Elimination of diclofenac from water using irradiation technology

The effluents of wastewater treatment plants, usually directly emitted to the environment, often contain the anti-inflammatory drug diclofenac (DCF). The paper investigates DCF elimination using irradiation technology. Hydroxyl radical and hydrated electron reactive intermediates resulting from water radiolysis effectively degrade DCF and strongly reduce the toxicity of the solutions. (OH)-O-center dot attaches to one of the rings of DCF, and hydroxylated molecules, 2,6-dichloroaniline and quinoid type compounds are the products. Hydrated electron adds to the chlorine atom containing ring, in the reaction quinoid type compounds and 4-chloroacridine form. At a 0.1 mM DCF concentration, a similar to 1 kGy absorbed dose is needed for the degradation of DCF molecules, but for mineralization of the products (in presence of O-2) an order of magnitude higher dose is required. For irradiation of wastewater after biological treatment a similar to 1 kGy dose is suggested. At this dose DCF and other drugs or metabolites present at mu g L-1 level are eliminated together with microorganism deactivation. (C) 2011 Elsevier Ltd. All rights reserved.