Electricity generation from polyalcohols in single-chamber microbial fuel cells

Six polyalcohols derived from lignocellulosic carbohydrates were investigated as carbon sources for electricity generation in single-chamber mediator-less microbial fuel cells (MFCs) for the first time. Electricity was directly generated from all polyalcohols tested, including pentitols (xylitol, arabitol, and ribitol) and hexitols (galactitol, mannitol, and sorbitol). Bacterial cultures initially enriched using acetate could be adapted to these substrates with varied adaptation times. The resultant maximum power density ranged from 1490+/-160 mW/m(2) to 2650+/-10 mW/m(2) at current densities between 0.58 mA/cm(2) and 0.78 mA/cm(2). Galactitol generated the highest maximum power density, while mannitol resulted in the lowest one. The estimated maximum voltage output at an external resistance of 120 Omega ranged between 0.24 V and 0.34 V with half saturation kinetic constants varied from 298 mg/L to 753 mg/L. The removal of chemical oxygen demand (COD) was above 91% for all polyalcohols except sorbitol (71%). Denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S rRNA gene segments of the anode biofilms showed the influence of substrates (polyalcohols) on the anode microbial populations.