Sediment Microbial Fuel Cell Power Boosted by Natural Chitin Degradation and Oxygen Reduction Electrocatalysts

Abstract

Abstract An economic and simple sediment microbial fuel cell (SMFC) design is evaluated to improve the recovery of energy from a river sediment, in terms of power density output (maximum power pick) normalized to the cathode surface. The organic matter content in the sediment is boosted by adding abundant, natural, and waste biomass (chitin) near the anode surface. The sluggish kinetics in the two‐electron reduction reaction of O 2 at the C‐cathode is replaced with an efficient four‐electron reduction reaction at the MnO 2 /C cathode. Five SMFCs composed of a common carbon fabric (CF) cathode and different unmodified anode materials, such as reticulate vitreous carbon (RVC: 10, 30, and 60 pore per inch, ppi), CF and commercial stainless‐steel (SS) mesh, are evaluated. The catholyte conductivity improved with Na 2 SO 4 . The results show that the power density output increased a 100‐fold when an MnO 2 /CF‐cathode is used with Na 2 SO 4 catholyte and the anolyte contained chitin. A microbial analysis of the SMFC sediment is performed. The bacterial groups identified, mainly Aminicenantia and Deltaproteobacteria , offer metabolic capacities to participate in the degradation of organic matter in the presence of chitin. Therefore, bacterial groups enriched in the anode biofilm produce electrical energy.

Key findings

• ▸The power density output increased by 100-fold when using an MnO2/C cathode with Na2SO4 catholyte and chitin in the anolyte.
• ▸The addition of chitin near the anode surface boosted the organic matter content in the sediment.
• ▸The MnO2/C cathode replaced the sluggish kinetics of the two-electron reduction reaction of O2 with an efficient four-electron reduction reaction.

Keywords

Identifiers

DOI

10.1002/clen.202000465

Journal

CLEAN – Soil, Air, Water

Year

2021