Suitability of wetland microbial consortium for enhanced and sustained power generation from distillery effluent in microbial fuel cell

Abstract

ABSTRACT Treatment of wastewater with concurrent energy production using Microbial Fuel Cell (MFC) has come up as a novel approach in the last 15 years. Constant efforts are being made to enhance energy output to make the process more sustainable. As the role of biofilm microbes in the process is being understood, suitability of the inoculum used assumes greater significance. Microbial consortium in wetland sediments, due to its prolonged exposure to anoxic environment with high organic matter and various biofilm-producing microbes, is likely to act as a suitable inoculum for MFC. The present study was conducted to analyze the suitability of wetland microbial consortium as a new inoculum in MFC, fed with distillery wastewater. The effect of concentration of wastewater, inoculum dose, and pH of anolyte on power output from the MFC were studied. Distillery wastewater of 50% strength led to production of highest power density (2.63 ± 0.05 W/m3), which was 34% higher than that of full-strength wastewater. Power generation by the MFC was found to be maximum (2.96 ± 0.03 W/m3) when inoculated with 1 g/L wetland sediment at anodic pH at 6.0. The internal resistance (IR), was 12% lower in the wetland sediment inoculated MFC (165.4 Ω) in comparison to that in the positive control MFC (188.2 Ω). Microbial composition of the anode biofilm was characterized using 16S metagenomic sequencing, which showed Proteobacteria as major phylum (46.5%) followed by Firmicutes (39.9%). β-Proteobacteria (28.1%) and γ – Proteobacteria (12.6%) that are known to consist of many electroactive species. Wetland microbial consortium thus shows great potential as an inoculum for MFCs giving high and sustained power from distillery wastewater. The study also resulted in 68.7 ± 1.7% of COD removal using optimized MFC conditions.