Simultaneous co-metabolic decolourisation of azo dye mixtures and bio-electricity generation under thermophillic (50°C) and saline conditions by an adapted anaerobic mixed culture in microbial fuel cells

Abstract

In this study, azo dye adapted mixed microbial consortium was used to effectively remove colour from azo dye mixtures and to simultaneously generate bio-electricity using microbial fuel cells (MFCs). Operating temperature (20°C-50°C) and salinity (0.5% w/v-2.5% w/v) were varied during experiments. Reactor operation at 50°C improved dye decolourisation and COD removal kinetic constants by approximately two fold compared to the kinetic constants at 30°C. Decolourisation and COD removal kinetic constants remained high (0.28h-1 and 0.064h-1 respectively) at moderate salinity (1% w/v) but deteriorated approximately four fold when the salinity was raised to 2.5% (w/v). Molecular phylogenetic analysis of microbial cultures used in the study indicated that both un-acclimated and dye acclimated cultures from MFCs were predominantly comprised of Firmicutes bacteria. This study demonstrates the possibility of using adapted microbial consortia in MFCs for achieving efficient bio-decolourisation of complex azo dye mixtures and concomitant bio-electricity generation under industrially relevant conditions.