Decolourisation and detoxification of rayon grade pulp paper mill effluent by mixed bacterial culture isolated from pulp paper mill effluent polluted site

This study deals with the decolourisation and detoxification of rayon grade pulp paper mill effluent by mixed culture of three bacterial strains having ligninolytic enzyme activity. These strains were identified as IITRP1 Pseudochrobactrum glaciale (FJ581024), IITRP2 Providencia rettgeri (GU 193984) and RCT2 Pantoea sp. (FJ755943) based on 16S rRNA gene sequencing. The results showed that mixed culture effectively reduced colour 96.02%, chemical oxygen demand (COD) 91% and biological oxygen demand (BOD) 92.59% of the pulp paper mill effluent within 216h of the incubation period. Maximum enzyme activity for lignin peroxidase (LiP), manganese peroxidase (MnP) and laccase were recorded at 48, 72 and 144h of the incubation period, respectively. The high performance liquid chromatography (HPLC) analysis of bacterial degraded samples showed 90% reduction of lignin and chlorophenol compared to the untreated sample. Further, gas chromatography-mass spectroscopy (GC-MS) analysis revealed that majority of the compounds present in the untreated sample were completely removed and only few metabolites were generated after bacterial treatment. The toxicity assessment of the pulp paper mill effluent on Vicia faba L. showed 40% reduction after bacterial treatment. However, untreated effluent sample showed inhibition of seed germination and alpha-amylase activity. (C) 2011 Elsevier B.V. All rights reserved.