Evaluation of a microbial fuel cell performance in co-treatment of landfill leachate and domestic wastewater - emphasis on organic matter removal and electricity generation

Abstract

The use of microbial fuel cells (MFC) for wastewater treatment is in the state-of-art. The scientific community is very interested in this technology because of electricity generation from pollutants removal. The most important studies regarding MFC were developed only in 2004, showing that MFC are such a new technology. Promising results were obtained in domestic wastewater treatment by MFC, but because this wastewater presents a low conductivity (among other factors) the generated power density was also low. It is well-known that power density is proportional to conductivity and, for this reason, promising results were obtained from landfill leachate treatment by MFC. This research project brings a novel proposal: the use of MFC in co-treatment of landfill leachate and domestic wastewater, focusing energy production from organic matter biodegradation and nitrogen removal. Landfill leachate co-treatment was deeply studied in previous researches developed in the EESC, and very interesting results were presented. This research project presents good chances of success, because the conductivity in the mixture leachate/domestic wastewater will be higher than that of domestic wastewater, whereas ammoniacal nitrogen concentration will be much lower than that of raw leachate, reducing the chances of inhibiting the metabolism of the microorganisms. It will be used a 48-L MFC, presenting two connected chambers: one anaerobic chamber (anode), for organic matter removal, and one aerobic chamber (cathode), for nitrogen removal by nitrification. The MFC will be inoculated with aerobic and anaerobic sludges and after the start-up period, it will be operated under a continuous-flow regime. At first, the MFC will be fed only with domestic wastewater (control condition) and then with leachate gradually added to domestic wastewater until the volumetric ratio of 2 % is reached. This volumetric ratio was chosen according to a recent research develop in the EESC, regarding leachate co-treatment with domestic wastewater. The MFC performance will be evaluated in function of the following decreasing hydraulic times: 24, 12, 8 and 6 h.