Research Projects

The broad objective of this proposal is wastewater treatment, carbon capture, and resource recovery. Microbial Carbon-capture Cell (MCCs) has been proposed for wastewater treatment that is effective in concomitant algal biomass production, carbon sequestration, and bioelectricity generation. For algal biomass valorization to resource recovery, a novel three-chamber bioelectrochemical system (BES) integrating Anaerobic Digestion Microbial Electrosynthesis (ADMES), Dark Fermentation (DF), and Microbial Electrolysis Cell (MEC) has been proposed. In this integrated MES-AD-MEC, the left chamber acts as both a single-chamber ADMES and anode zone of MES, the middle chamber as DF zone, and the right chamber as cathode zone of MES. An anion exchange membrane (AEM) separates the left and middle chambers, while a cation exchange membrane (CEM) separates the middle and right chambers. The left chamber contains two electrodes (one anode and one cathode), and the right chamber only one electrode (cathode). For electricity input, the ADMES and MEC share a single anode electrode, while they have separate cathodes. The design of this integrated ADMES-DF-MEC is based on the limitation-solving and resource recovery approach. The ADMES-DF-MEC can be effective in the recovery of H2, NH3, CH4, and residual digestate. This residual digestate can be thermochemically converted to biochar. In the proposed research, wastewater will initially enter the anode chamber of the continuous flow MCC, where exoelectrogens will oxidize the organic contaminants to generate CO2, H+, and e–. The anodic effluent will further enter the cathode chamber, where nutrient removal, CO2 sequestration, and improvement in dissolved oxygen (DO) will occur owing to algal cultivation in it. Electricity generation also occurs as e– flow through the external electrical circuit, and H+ through the CEM to reach the cathode for DO reduction into H2O. The DO elevation induces the oxygen reduction reaction for bioelectricity generation. The algal biomass will be harvested from the cathodic effluent. The algal biomass slurry after pretreatment will be initially subjected to the DF chamber of integrated ADMES-DF-EC, where enriched inoculum will facilitate fermentation to result in the production of H2, volatile fatty acids (VFAs), and ammonium. The VFAs and ammonium are the major inhibitors of H2 production in DF. Thus, VFAs from the DF can be diffused through an AEM to the ADMES chamber under concentration and electrical gradient for CH4 recovery. Similarly, ammonium can be diffused through a CEM from DF to cathode chamber of MEC, for the recovery of NH3 and H2. Further, the residual digestate will be valorized to biochar. The proposed research will start from the laboratory scale for preliminary investigation, and further, it will be replicated on an upscaled BES platform. The overall proposed research follows the circular bioeconomy concept by recovering energy, nutrients, carbon, and valorizing biomass.