A live bio-cathode to enhance power output steered by bacteria-microalgae synergistic metabolism in microbial fuel cell

Abstract

Microbial fuel cells (MFCs) are energy transducers that convert organic matter into electricity via anaerobic respiration of electro-active microorganisms. An avenue of research in this field is to utilize microalgal biomass for electricity generation in the MFCs. Here, Chlorella sp. is used as substrate in anode and as live-culture to constitute a bio-cathode. Addition of flue-gas (10 ± 2% CO2, v/v) in the biocathode leads to increase in biomass production (1.34 gL-1) and CO2 sequestration (190.9 mgL−1d−1). The performance of microalgae-driven green MFC (MFC-2) is compared with control MFC (MFC-1) which receives tap water and synthetic wastewater in its cathodic and anodic compartment, respectively. With the increase in biomass concentration from 0.08 (t = 0) to 1.34 gL-1 a maximum increase of 55% in power density is obtained in MFC-2 than MFC-1. Chronoamperometric curves obtained in this study shows enhanced current production (3.1 mA) in biocathode. Along with a stable voltage of 0.852 ± 01 V and cathodic dissolved oxygen concentration of 11.2 mgL−1, the removal of chemical oxygen demand (75 ± 5%) is also found to be better in MFC-2. The results demonstrate the novelty and efficacy of bacterial-algal synergistic metabolism in producing bio-electricity using inorganic and organic wastes.