Application of photocatalytic oxidation treatment to pretreated and raw effluents from the Kraft bleaching process and textile industry

Abstract

Treatability of mixed raw, coagulated and biologically pretreated textile and pulp wastewater and effluents from different process stages by enhanced heterogenous photocatalytic oxidation process was investigated. Treatment performances have been evaluated in terms of COD, TOC, BOD 5, and colour removal. Results clearly indicate that photocatalytic oxidation process enhanced with 15 mM H 2O 2 was more efficient in removal of pollutants for pretreated wastewater samples. By the application of photocatalytic treatment, 52 and 87% COD removals were obtained for biotreated Kraft bleaching and textile effluents, respectively. Addition of only 1 mM ferric ion speeded up the oxidation time of the textile effluent significantly, but it had no impact on total COD reduction. While complete colour removal of the textile wastewater was achieved within the first hour of photocatalytic treatment, complete decolourisation could not be obtained for pulp effluents, except for the coagulated wastewater throughout the reaction period. Biologically pretreated textile wastewater was found to have potential for reuse after photocatalytic treatment.