Effect of Salt Enrichment on Electricity Generation and Waste Water Treatment in a Microbial Fuel Using Oxygen as Electron Acceptors

Abstract

One way to reduce treatment cost while producing useful products from wastewater is the microbial fuel cell (MFC) technology. It provides a means of treating wastewater with simultaneous production of energy. In the present study, the H-type MFC was used to study the effect of salt enrichment on electricity generation using carbon and copper electrodes with oxygen as electron acceptor. Wastewater from septic tank was used as substrate, one set of which was enriched with 1M NaCl. The voltage and current generated were monitored using a multimeter which was connected to the anode and cathode by a copper wire. Oxygen was used as electron acceptor at the cathode chamber. Voltage and current readings were taken per hour per day for 15days. Wastewater treatability was determined by comparing the biological oxygen demand (BOD), dissolved oxygen (DO), chemical oxygen demand (COD) and total dissolved solid (TDS) of the wastewaters before and after treatment. The results show that the fuel cells generated voltages and currents that varied according to the electrode used. Salt enrichment enhanced the efficiency of both current and voltage generation in the MFCs. Carbon electrode MFC performed better than copper electrode MFC. Both the enriched and the un-enriched MFCs had very high percentage removal of BOD, DO, COD and TDS in both carbon and copper electrode MFCs. Do and BOD percentage removals were at least 60% in all the MFCs while the CODs removals were at least 50% in all the treatments. The least percentage wastewater parameter removal was observed in TDS of salt-enriched copper electrode MFC. The study proved that wastewater can be conveniently treated using MFC. The best option would be to use salt-enrichment in a carbon-electrode microbial fuel cell.