ELECTROCHEMICAL OXIDATION PRETREATMENT OF REFRACTORY ORGANIC POLLUTANTS

Refractory pollutants, including lignin, tannic acid, chlortetracyclin e, and EDTA, were destroyed by an electrochemical oxidation method to evaluate the applicability of this method for industrial wastewater pr etreatment. Operation parameters, such as supporting electrolyte, curr ent density, and electrolyte concentration, have been investigated for their influences on COD removal efficiencies during electrolysis. In addition, gel permeation chromatography (GPC), Microtox test, and tota l organic halogen (TOX) analyses were performed to monitor the changes of organic characteristics of these refractory pollutants. Experiment al results show that, among sulfate, nitrate, and chloride, chloride w as the best supporting electrolyte, and during electrolysis, both COD and color removal efficiencies were improved by increasing current den sity and chloride concentration. From GPC analysis results, the electr ochemical oxidation process readily destroys high-molecular-weight (HM W) organics. Microtox test results also show that the process can redu ce the toxicity of these refractory organic compounds. In addition, TO X concentrations were found to increase at the beginning but then decl ine during the electrolysis. The above results suggest that the electr ochemical oxidation process, which has good efficacy for detoxificatio n and destruction of refractory pollutants, is a promising method for wastewater pretreatment. (C) 1997 IAWQ. Published by Elsevier Science Ltd.