Abstract
The white rot fungi that are able to decolorize melanoidin were examined for the ability to remove the color from heat treatment liquor of waste sludge (HTL) obtained from the sewage wastewater treatment plant. Coriolus hirsutus was selected, and the fungal HTL decolorization was further characterized since the strain showed the highest HTL-decolorizing ability. The decolorization of the HTL supplemented with 20 g/l glucose was observed concomitantly by the fungal growth, and the decolorization efficiency reached 80% within 8 days. Fractionation of the decolorized liquor with XAD-7 resin revealed a considerable color reduction of fraction III, which is one of two major colored fractions of intact HTL, and a complete color removal of fraction I, which is the other one. Incubation of the fraction III components with the fungus resulted in a color reduction up to about 70%. Only 18% of the color reduction level was due to the adsorption of the components onto the pellets. Incubation of the fraction I components, on the other hand, also demonstrated that a small portion of the color reduction was due to the adsorption. Therefore, the color removal of HTL by C. hirsutus resulted from a substantial degradation of the colored components.
