Solid phase bio-electrofermentation of food waste to harvest value-added products associated with waste remediation

摘要

A novel solid state bio-electrofermentation system (SBES), which can function on the self-driven bioelec-trogenic activity was designed and fabricated in the laboratory. SBES was operated with food waste as substrate and evaluated for simultaneous production of electrofuels viz., bioelectricity, biohydrogen (H_2) and bioethanol. The system illustrated maximum open circuit voltage and power density of 443 mV and 162.4 mW/m~2, respectively on 9th day of operation while higher H_2 production rate (21.9 ml/h) was observed on 19th day of operation. SBES system also documented 4.85% w/v bioethanol production on 20th day of operation. The analysis of end products confirmed that H_2 production could be generally attributed to a mixed acetate/butyrate-type of fermentation. Nevertheless, the presence of additional metabolites in SBES, including formate, lactate, propionate and ethanol, also suggested that other metabolic pathways were active during the process, lowering the conversion of substrate into H_2. SBES also documented 72% substrate (COD) removal efficiency along with value added product generation. Continuous evolution of volatile fatty acids as intermediary metabolites resulted in pH drop and depicted its negative influence on SBES performance. Bio-electrocatalytic analysis was carried out to evaluate the redox catalytic capabilities of the biocatalyst. Experimental data illustrated that solid-state fermentation can be effectively integrated in SBES for the production of value added products with the possibility of simultaneous solid waste remediation.