WET OXIDATION AS A PRETREATMENT METHOD FOR WASTEWATERS CONTAMINATED BY BIORESISTANT ORGANICS

The partial wet air oxidation of aqueous solutions of polyethylene gly col, a model organic pollutant typically found in wastewaters of polym er-manufacturing, has been investigated at temperatures from 383 K to 513 K and oxygen partial pressures from 2 MPa to 3 MPa. The progress o f the reaction was investigated in terms of COD and TOC removal, while fragmentation of the original polymer to lower molecular weight compo unds was followed by means of liquid chromatography. The impact of var ious heterogeneous and homogeneous catalysts on the kinetics and mecha nisms of the reaction has also been studied. Conversion of the model c ompound through various oxidation intermediates to end-products, such as carboxylic acids and oligomers, could be easily achieved even under mild operating conditions, while further total oxidation proved to be difficult even under more severe conditions. Catalysts were found to be, in general, capable of increasing the rates of total uncatalysed o xidation, The implications for complete removal of bioresistant organi c pollutants by partial wet oxidation followed by a biological treatme nt step are also discussed. (C) 1997 IAWQ. Published by Elsevier Scien ce Ltd.