Decolourization of Vat Dyes by Bacterial Isolates Recovered from Local Textile Mills in Southwest, Nigeria

Abstract

Aims: Waste water emanated from the use of synthetic dyes obtained from different textile and other dyestuff industries require treatment before they are discharge into the environment to prevent groundwater contamination. Considerable interest has been on decolourisation and degradation of dyes by microorganisms due to its efficiency and duration of treatment. In this study bacterial isolates were recovered from textile dye effluent and used in decolourization of textile dyes to non-toxic metabolites. Study Design: Effluent samples were collected from two different local textile mills in Abeokuta, Ogun state, Nigeria. Place and Duration of Study: Effluent sample were collected from local textile mills in Abeokuta, Ogun state during the dry season in the month of November and December, 2013 Methodology: Ability of bacterial strains isolated from textile wastewater were screened for vat dyes decolourization and high decolourization potential isolates were used for decolourization of different vat dyes. Results: Thirty-four bacterial strains were isolated from textile wastewater. Screening of the thirty- four bacterial isolates on Luria-Bertani Agar medium supplemented with 100 mg/L of dye revealed four bacterial isolates as potential isolate for dye-decolourisation. The four bacterial isolates are: Bacillus firmus, Bacillus macerans, Staphylococcus aureus and Klebsiella oxytoca. Decolourisation of vat black dye using all the potential four isolates showed that Bacillus macerans had highest decolourising potential of 75.04% while Bacillus firmus had the lowest decolourising ability of 41.42%. Klebsiella oxytoca had the highest decolourisation potential of 69.68% for vat brown dye while Staphylococcus aureus had the least decolourisation potential (33.33%). Bacillus firmus after 5 days showed the highest vat red dye decolourisation of 81.27% while Staphylococcus aureus had the least decolourisation activity of 34.67%. Conclusion: Application of the bacterial strains under natural environmental conditions in the decolourisation is an indication of its ability and effectiveness in treatment of wastewater containing dye.