Abstract

The degradation, by several advanced oxidation reactions, of a pulp mill ECF bleaching effluent, was studied. The initial biodegradability of the organic matter present in the effluent, estimated as the BOD(5)/COD, was low (0.3). When the effluent was submitted to ozonation and to five different advanced oxidation systems (O(3)/UV, O(3)/UV/ZnO, O(3)/UV/TiO(2), O(2)/UV/ZnO, O(2)/UV/TiO(2)), the biodegradability increase significantly. After five minutes of reaction, the O(3)/UV system, appears as the most efficient in to transform the organic matter to more biodegradable forms. A similar effect was observed when the effluent was submitted to an activated sludge treatment. The GOD, TOC and toxicity reduction correlated well with the biodegradability enhancement after AOPs treatments. (C) 1999 Elsevier Science Ltd. All rights reserved.