Microbial fuel cell (MFC) is an evolving technology for anaerobic bioenergy generation using
electrodes and organic wastewater as a feedstock for catabolic activities of electrogenic
bacteria with subsequent electricity generation. There are growing interests in microbial fuel
cells (MFCs) for anaerobic bioenergy generation. Researchers in this discipline continue to be
most interested in finding suitably affordable electrode materials. However despite the large
varieties of commercially available electrodes only few are suitable for electro-active
bacterial colonization during biofilm formation in MFCs and most of these electrodes are cost
prohibitive. Hence there is need to search for low-cost alternative electrodes for MFCs. The
focus of this study was to develop electrodes locally from corncob biomass for application in
microbial fuel cells. Pyrochars were produced by pyrolysis and subsequently activated with
steam or potassium hydroxide (KOH). A comparative bioelectricity generation from process water
of hydrothermal carbonization of spent bear grains and treated-biogas digestate was carried
out in dual-chambered MFCs using graphite rod and the locally developed potassium
hydroxide-activated corncob pyrochar (KAC) and steam- activated corncob pyrochar electrodes. A
standard strain of actively dividing cells of the electroactive bacterium Shewanella oneidensis
MR-1 was used as inoculum for bioelectricity generation. Conclusively the chemical activation
of the pyrochar with KOH resulted in increased electrical conductivity pore diameter and most
importantly the material's surface area and a highest Coulombic efficiency of 75 % was recorded
from the MFC operated with treated biogas digestate and KAC electrode in a shorter residence
time.
