The ability of Emericella nidulans var. lata, Neurospora intermedia and Bacillus sp. to treat distillery spent wash in a three stage bioreactor was investigated. Process parameters were optimized in shake flask cultures with the individual strains before treatment of the effluent in a 15-l bioreactor. Treatment was first carried out by the fungi followed by bacteria. The treated effluent showed significant reduction in color (82%) and COD (93%) after 30 h. Metabolites formed after degradation of complex polymers in distillery effluent were assayed by gas chromatography-mass spectroscopy and included furan, simple acid types and organic compounds. Denaturing gradient gel electrophoresis of 165 rDNA and 185 rDNA sequences amplified from DNA isolated from the reactor communities indicated the presence of other organisms besides those introduced initially. The microbial communities were able to carry out bioremediation of distillery effluent and produce discharge that conforms to safety standards. (C) 2010 Elsevier Ltd. All rights reserved.