Coupling Biogas Upgradation and Dairy Wastewater Treatment for Simultaneous Carbon Capture and Bioelectricity Generation Using an Algae-Assisted Microbial Fuel Cell

Abstract

This study demonstrates the application of an algae-assisted microbial fuel cell (AMFC) in biogas upgradation. A proof-of-concept lab-scale biorefinery is presented that couples raw biogas upgradation with dairy wastewater treatment using an integrated approach of a bicarbonate-based integrated carbon capture and algae production system (BICCAPS) and a microbial fuel cell (MFC). The treated biogas had a CH4 content of 85–93% with no traces of CO2, H2S, or NH3. The system was able to remove H2S and NH3 from biogas with high sulfide (961 to 2800 ppm) and ammonia (1300 to 2800 ppm) concentrations. The power and current densities obtained from the MFC were 17.3 mW/m2 and 170 mA/m2, respectively. The normalized energy recovery (NERV) from this process was 6.91 kW h/m3. The CO2 captured in the form of bicarbonate led to a total algal biomass production of 6.8 (±0.15) g/L. Integrating the BICCAPS with an algae-assisted MFC makes the overall process more sustainable, as it can simultaneously treat wastewater, generate bioelectricity, upgrade biogas, and mitigate carbon (CO2) and nitrogen (NH3) emissions.