Abstract:
Microbial Fuel Cells are bio electrochemical systems that produce electricity from the catalysis of organic matter by the interplay of aerobic and anaerobic microbes. It is possible to directly generate electricity using bacteria while accomplishing wastewater treatment in processes based on microbial fuel cell technologies. For this purpose, samples were collected from Nala Lai, Rawalpindi and Sewage Treatment Plant, I-9, Islamabad. Five lab scale sediment MFCs were constructed, out of which, two were augmented with Glucose as mediator and one was used as control. Each MFC was constructed by submerging graphite anode in sediment bed while graphite cathode was suspended in the waste water. These electrodes were connected to insulated copper wires. During investigation, the whole apparatus was kept at room temperature in the laboratory for a period of eight weeks. Prior to set up of MFCs and at the end of incubation period, their Biological Oxygen Demand and Chemical Oxygen Demand were determined in order to analyze the waste treatment efficiency. Voltage and current were also measured over the period of eight weeks to determine the amount of electricity produced by each MFC. The Biological Oxygen Demand of Nala Lai and STP MFCs were significantly reduced from 234 to 95 ppm and 58 to 40 ppm respectively. Similarly, the BOD of Nala Lai with mediator MFC and STP with mediator MFC was reduced to 106 ppm and 31 ppm respectively. The chemical oxygen demand of Nala lai MFC and STP MFC was reduced from 455 ppm to 136 ppm and 85 ppm to 45 ppm respectively. The COD of Nala lai with mediator MFC and STP with mediator MFC was reduced to 142 ppm and 37 ppm. Average power densities, over the period of eight weeks, of 0.125 W/m2 and 0.008 W/m2 were obtained from Nala Lai and STP I-9 MFCs respectively. 0.077 W/m2 and 0.036 W/m2 were obtained from Nala Lai with Mediator and STP with mediator MFC. The results indicated that waste water of Nala Lai can be used as potential source of electricity with the secondary benefits of its treatment, without utilizing any mediator. More ever, electricity production should also be integrated in treatment procedures in I-9 STP.
