Enhanced biodegradability by oxidative and radiative wastewater treatment

Processes for oxidative destruction of non-biodegradable substances in wastewater of the pulp and paper industry are using oxidants, partly in combination with catalysts or high energy radiation including UV-radiation. We summarize these processes as oxidative and radiative treatment. Instead of aiming at a total oxidation of the organic matter a partial oxidation of the persistent substances can be achieved with far less costs in biological treated wastewater. This leads to a significant improvement of the biodegradability. A subsequent biological treatment will eliminate therefore a high proportion of the remaining organic matter, which before was persistent. Special processes are needed for the additional biological treatment due to the low BOD concentration. Low loaded biofilm reactors like submerged granular biofilters have been established as the most preferred technique for this treatment. A process of this type that has been extensively studied by us is ozonation of biological treated wastewater followed by biological treatment with biofilters. (C) 1997 IAWQ.