Polycyclic Aromatic Hydrocarbons (PAHs) Degradation and Detoxification of Water Environment in Single-chamber Air-cathode Microbial Fuel Cells (MFCs)

The influence of microelectrogenesis on PAHs degradation and detoxification operated by Pseudomonadaceae, Bacillaceae, Staphylococcaceae and Enterobacteriaceae was investigated in water environment. Single chamber, air-cathode MFCs and bioreactors were filled with the microbial pool (10(7)-10(8) CFUmL(-1)) inoculated in a 400mL Winogradsky saline solution containing no other carbon and energy source than naphthalene (80 ppm), phenanthrene (40 ppm), pyrene (40 ppm), benzo(a)pyrene (20 ppm). MFCs and bioreactors operated at 25 degrees C for thirteen weeks. Power Density (PD) and Current Density (CD) outputs as well as PAHs degradation rate were measured. The toxic effect of PAHs suspension vs.Raphidocelis subcapitata was quantified by EC1, EC20, EC50, LOEC and NOEC calculations. The results showed a significant variability in PD and CD outputs, with highest PD of 300 mW m(-3) and 25 mA m(-3). After 5 weeks, the overall PAHs concentration in MFCs decreased of a 90%. COD and TOC removal respectively of 62% and 73% after 11 weeks was achieved in MFC inoculated with bacteria (MFC2). Ecotoxicological tests showed for MFCs a lower toxic effect vs.P.subcapitata when bacteria are present. Microelectrogenesis just sped up microbial metabolism rather than take advantage from the interaction of PAHs with graphite electrodes.