Isolation and characterisation of decolorising bacterial strains isolated from textile dyeing wastewater

Abstract

Directed discharge into water sources of untreated textile dyeing wastewater will cause seriously environmental contamination. Various kinds of physico-chemical methods have been in use for the treatment of the wastewater. However, these methods are not environment friendly and cost-effective, and hence become commercially unattractive. Many microorganisms strains belonging to the different taxonomic groups of bacteria, fungi, actinomycetes, and algae have been reported for their ability to decolourise dyes. This study was conducted to investigate the decolorisation of Red FN2BL by using bacterial strains isolated from textile dyeing wastewater. Three different bacterial strains A2, A9 and A14 exhibited high decolorization effects were selected. Decolorisation effect of strain A9 was 80.6%>A14 (67.5%)>A2 (34.6%) in stable cultural condition and was A9 (63.3%)>A14 (34.9%)>A2 (26.9%) in shaking cultural condition. The strain A9 was selected for evaluating the effects of some cultural conditions. Strain A9 showed maximum decolorisation ability at pH between 6 and 7, temperature of 35oC, and bacterial density of 5-15%. Starch and (NH4)2SO4, NH4Cl or yeast extract were found to be the optimum condition for decolorisation. In brief, the strain A9 reveals a great potential for application in the textile dyeing wastewater treatment.