Decolorization of kraft bleach plant effluent with the white rot fungus Trametes versicolor

Abstract The screening of 11 strains of white rot fungi for their ability to decolorize E 1 effluent from a kraft bleach plant showed that Trametes versicolor B7 was the most efficient. Over 80% of the colour of the effluent was removed within 3 days in the shake culture in the presence of glucose. The fungus was used in the form of pellets, allowing its use in large amounts and eliminating the problem of recycling the biomass. The mycelial pellets oxidized the chromophores of the effluent in the presence of any of the co-substrates, sucrose, glucose, starch, ethanol, carboxymethyl cellulose, microcrystalline cellulose, pulp and malt extract. The highest decolorization was obtained in the case of glucose. The optimum pH and temperature were found to be 4·5–5·5 and 30°C respectively. In the batch reactor with an effluent of 7000 colour units, the maximum colour reduction of 93% was obtained in 48 h with a chemical oxygen demand (COD) reduction of 35%. In the continuous reactor the same level of colour/COD reduction was obtained in a 38 h residence time. No loss in decolorization ability of mycelial pellets was obtained when the reactor was operated continuously for more than 30 days.