Several ligninolytic microorganisms isolated from the environment of a small pulp and paper mill were evaluated for their ability to
decolorize dark brown colored effluents of an agriresidue-based pulp and paper mill and their decolorization efficiency was compared with
two known lignin degrading organisms, Phanerochaete chrysosporium and Trametes versicolor. Two isolates, identified as Aspergillus
fumigatus and Aspergillus flavus produced higher degrees of color reduction. A. fumigatus showed highest efficiency for effluent
decolorization and was capable of producing extracellular laccase, manganese peroxidase and xylanase. This culture was capable of
decolorizing effluents over pH range 6.0–9.0, the optimum being pH 8.0 and hence no adjustment of effluent pH for decolorization was
necessary. Cellulose, sucrose, glucose and xylose could be used as co-substrate and no additional nitrogen source was necessary for effluent
decolorization. Studies on molecular size distribution of untreated effluent and effluent decolorized by A. fumigatus showed that the high- and
medium-molecular weight colored compounds are biochemically degraded and depolymerized.