Electricity generation from synthetic substrates and cheese whey using a two chamber microbial fuel cell

In this study, the possibility of electricity generation from diluted cheese whey in a two-chamber mediator-less microbial fuel cell (MFC) was investigated. Synthetic substrates such as glucose and lactose were also used for characterization of the MFC and for microbial acclimation at the anode compartment. The maximum power density obtained using diluted cheese whey was 18.4 mW/m2 (normalized to the geometric area of the anodic electrode, which was 13.8 cm2), corresponding to a current density of 80 mA/m2 and a MFC voltage of 0.23 V. The coulombic efficiency ɛcb was very low (only 1.9%), implying that a pretreatment step of raw cheese whey is essential prior to use. For comparison, in the case of sugars (glucose and lactose) the obtained maximum power density was 15.2 mW/m2 with ɛcb equal to 28% for glucose and 17.2 mW/m2 with ɛcb equal to 22% for lactose. Impedance spectroscopy measurements showed that the dominant contribution to the cell overpotential was due to the ohmic resistance of the MFC. The contribution of the electrode overpotentials was also significant, mainly that of the cathode overpotential.