Biomas photochemistry XV: Photobleaching and biobleaching of Kraft effluent

Abstract

The ascomycete Chrysonilia sitophila (TFB-27441 strain), in the form of mycelial pellets or immobilized in nylon, provides an effective means to decolorize lignin-containing Kraft E 2 stage effluent from a wood treatment process. Mycelial pellets adsorb 25%–30% of liquor chromophores of which 60%–65% are oxidized. Culture broth containing lignindegrading enzymes efficiently removes color by oxidation in the presence of H 2O 2 in 6 h. Kraft effluent is also oxidatively decomposed by a semiconductor-photocatalyzed reaction in an aqueous solution containing oxygen and semiconductor powder. Under continued illumination, the solution becomes colorless and the molecular weight distribution indicates almost total mineralization in 2 h. Effluent pre-irradiation, followed by tratment with a filtrated fungal culture, efficiently enhances effluent decolorization to an extent of 95% in around 2 h. The combined photobleaching and biobleaching procedure appears to be an efficient process with great potential for industrial effluent treatment.