Degradation of triethylene glycol dimethyl ether by ozonation combined with UV irradiation or hydrogen peroxide addition

Ozonation of pure aqueous solutions of the polar aliphatic refractory triethylene glycol dimethyl ether (TEGDME) which is a typical representative of organic solutes of oil reclaiming wastewaters does not lead to effective mineralization unless high ozone doses are applied. Small doses of UV irradiation do not markedly increase TEGDME mineralization by ozonation, but transformation to more oxidized products (mainly carboxylic acids containing methoxy and/or ethoxy groups) which are biodegradable to a higher degree than TEGDME. Addition of high concentrations of hydrogen peroxide during ozonation results in efficient increase of TEGDME mineralization, however. The presence of humic acids - which is a consequence of biological treatment of wastewaters containing biodegradable organic constituents - has a beneficial effect on transformation of TEGDME during ozonation or ozone/UV treatment because hydrogen peroxide is formed during ozonation of humic acid C-C double bonds. (C) 1997 IAWQ. Published by Elsevier Science Ltd.