Özet:

There are growing interests in microbial fuel cells (MFCs) for anaerobic bioenergy generation. MFC uses electrodes and organic wastewater as substrate for electrogenic bacteria to catabolize and generate power. Researchers in this discipline continue to be most interested in finding suitably affordable electrode materials. The focus of this study was on comparative bioelectricity generation from process water of hydrothermal carbonization (HTC) (pH = 5.99) and treated–biogas digestate (pH = 7.97) using locally developed corncob pyrochar electrodes and graphite in dual-chambered MFC. The electrodes used in this study were graphite rod (non-porous and very low surface area), potassium hydroxide (KOH)–activated corncob pyrochar (KAC) of Brunauer-Emmett-Teller (BET) surface area, 1626 m2 / g and steam- activated corncob pyrochar (SAC) with 485.8 m2 / g. Each electrode was separately tested in the MFC, some charged with HTC process water, and others with treated biogas digestate. An overnight culture of actively dividing cells of Shewanella oneidensis MR-1 (Electro-active bacterium) at logarithmic phase of growth was seeded into each of the anode chamber as inoculum. The anode chambers were sealed off to achieve anaerobiosis and the cathode chambers sparged continuously with air. The MFCs were operated for 30 d and results obtained were recorded. The highest power outputs achieved were 323.8 µW and 316.8 µW from HTC process water with SAC and biogas digestate with KAC electrodes respectively at an external load of 47 ?. The initial Chemical Oxygen Demand (48780 mg / L), Dissolved Organic Carbon (4000 mg / L), and Total bounded Nitrogen (5600 mg L-1) of the biogas digestate decreased significantly to 36405, 3610 and 4300 mg / L respectively in the MFC with KAC electrodes. A Coulombic efficiency of 75 % was recorded from the MFC operated with treated biogas digestate and KAC electrode in a significantly shorter residence time, making it more efficient than its counterpart with SAC electrode, which had a lower Coulombic efficiency of 64 %.<

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