On the evaluation of filtered and pretreated cheese whey as an electron donor in a single chamber microbial fuel cell

In the present study, the valorization of cheese whey (CW) as an electron donor in an air-cathode single-chamber microbial fuel cell (MFC) was studied. Filter-sterilized raw and pretreated-acidified diluted CW (after 48 h of fermentation at mesophilic temperature) were used as substrates, in order to investigate the effect of the two different handlings on the MFC performance. The pretreatment-acidification experiments were performed under different operational conditions (initial dilutions giving chemical oxygen demand (COD) concentrations of 2 and 4 g/L as well as initial pH adjusted to 6.7 and without pH adjustment) in order to obtain maximum acidification efficiency and energy recovery, in the form of hydrogen. The effect of organic load on the efficiency of the MFC was studied, aiming at exploring the possibility of achieving a successful operation at the highest possible initial concentration of CW (smallest dilution). The experimental results showed that CW is a suitable and promising substrate for electricity production using MFC, with a maximum power density of 3.26 W/m(3) (0.33 MJ/kg COD) for filter-sterilized CW diluted to an initial concentration of 0.8 g COD/L. Combining MFC technology with the pretreatment/acidification process, during which hydrogen is also produced, a total energy of 2.37 MJ/kg COD could be recovered.