Valorization of biodigestor plant waste in electrodes for supercapacitors and microbial fuel cells

This study aims at demonstrating that wastes from anaerobic biodigester plants can be effectively valorized as functional materials to implemented in technologies enable efficient energy management and water treatment, therefore simultaneously addressing the Water-Energy-Waste Nexus challenges. Lignin, main solid residue of plant, has been into activated biochar with a mild activation agent, like KHCO3, produce electrode supercapacitors microbial fuel cells. In addition, same sludge is liquid effluent plant exploited inoculum electrolyte for MFC. The lignin derived carbons obtained lignin/KHCO3 mass ratios 1:0.5 (LAC-0.5) 1:2 (LAC-2) comprised mesopores micropores displaying BETs 1558 m2/g 1879 m2/g, respectively. LAC-2 carbon exhibited superior specific capacitance 114 F/g 2.5 M KNO3 respect LAC-0.5. A supercapacitor electrodes was built power up 10 Wh/kg 6.9 kW/kg, Durability tests showed device able maintain retention 84.5% after 15,000 charge-discharge cycles. lignin-derived were also studied electrocatalysts ORR neutral medium. higher electrocatalytic activity than interconnected porous network high surface area made suitable dual applications. feasibility use LAC 2 incorporated an air breathing cathode MFC applications reported.