Electrical generation and methane emission from an anoxic riverine sediment slurry treated by a two-chamber microbial fuel cell

Abstract

A two-chamber slurry microbial fuel cell (SMFC) was constructed using black-odorous river sediments as substrate for the anode. We tested addition of potassium ferricyanide (K 3 [Fe(CN) 6 ]) or sodium chloride (NaCl) to the cathode chamber (0, 50, 100, 150, and 200 mM) and aeration of the cathode chamber (0, 2, 4, 6, and 8 h per day) to assess their response on electrical generation, internal resistance, and methane emission over a 600-h period. When the aeration time in the cathode chamber was 6 h and K 3 [Fe(CN) 6 ] or NaCl concentrations were 200 mM, the highest power densities were 6.00, 6.45, and 6.64 mW•m −2 , respectively. With increasing K 3 [Fe(CN) 6 ] or NaCl concentration in the cathode chamber, methane emission progressively decreased (mean ± SD: 181.6 ± 10.9 → 75.5 ± 9.8 mg/m 3 •h and 428.0 ± 28.5 → 157.0 ± 35.7 mg/m 3 •h), respectively, but was higher than the reference having no cathode/anode electrodes (~ 30 mg/m 3 •h). Cathode aeration (0 → 8 h/day) demonstrated a reduction in methane emission from the anode chamber for only the 6-h treatment (mean: 349.6 ± 37.4 versus 299.4 ± 34.7 mg/m 3 •h for 6 h/day treatment); methane emission from the reference was much lower (85.3 ± 26.1 mg/m 3 •h). Our results demonstrate that adding an electron acceptor (K 3 [Fe(CN) 6 ]), electrolyte solution (NaCl), and aeration to the cathode chamber can appreciably improve electrical generation efficiency from the MFC. Notably, electrical generation stimulates methane emission, but methane emission decreases at higher power densities.

Cobalt-Intercalated Birnessite-Type Manganese Oxide Catalysts for Low-Cost Cathodes in Microbial Fuel Cells

“…Microbial fuel cells (MFCs) are a technology that generates electrical energy by using electrons released by electrogenic bacteria, which are generally found in rivers, lakes, wastewater, and soil during their biological activity of decomposing organic matter (Xiao, et al, 2022, Nawaz, et al, 2022. Since the organic matter in rivers and wastewater can be practically converted into electrical energy, this technology is expected to be an effective solution to both organic pollution and energy problems (Khandaker, et al, 2021).…”