Electricity and fertiliser production using microbial fuel cell stacks for possible integration with hydroponics

Abstract

Sewage management and sanitation are global concerns, especially in urban areas due to lack of treatment infrastructure. Here, we stacked 40 ceramic microbial fuel cells in two plastic trays (MFC tray-1 and MFC tray-2) to produce both electricity and liquid fertiliser directly from raw sewage. MFC tray-1 and MFC tray-2 produced power of up to 21.78 mW and 18.89 mW, respectively, with synthetic urine. Maximum power output values were 19.1 mW (63.82 mA) and 14.9 (56.38 mA) for sewage-fed MFC tray-1 and MFC tray-2, respectively. Therefore, each ceramic MFC unit in both trays achieved a power performance of up to 1.02 mW and 0.85 mW with synthetic urine and raw sewage, respectively. The rate of catholyte (fertiliser) production in each MFC tray was 1.2 L of catholyte/48 h from 2.5 L of feedstock. The catholyte from sewage-fed MFCs has been observed to have antimicrobial properties, and it is composed of NO3−, PO4−2, and K+ at concentrations of 25 ± 1 [mg/kg], 9 ± 3 [mg/kg], and 95 ± 14 [mg/kg], respectively. Ceramic-microbial fuel cell stacks therefore efficiently harness electricity and produce liquid fertiliser from sewage, offering seamless integration with hydroponics to grow vegetables in a self-powered, hygienic, and sustainable manner.

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ORCID for Ioannis Andrea Ieropoulos: orcid.org/0000-0002-9641-5504

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