A study of a microbial fuel cell battery using manure sludge waste

The cell voltage and power performance of a microbial fuel cell utilising waste carbohydrate as a fuel, that does not use a mediator, catalysts or a proton exchange membrane, is reported. Tests were conducted with the cell operated essentially as a battery using manure sludge as fuel and with oxygen reduction in an aqueous solution. Using carbon cloth as both anode and cathode, the cell produced peak power of the order of 5 mWm(-2). The cell performance was not greatly influenced by the quantity of fuel used and required a suitable separation between the cathode, anode and sludge/water interface. Agitation of the sludge did not adversely affect the cell performance, indicating that a continuous fuel cell system could be operated using the manure sludge. Using a platinised carbon cathode doubled the power density to over 10 mW m(-2). The use of nickel as an alternative cathode catalyst was not found to be effective under the conditions of operation of the cell. The cell power performance was found to be consistent and stable over the 3 month duration of the tests, after which point over 95% consumption of carbohydrate was achieved. Examination of the carbon anodes after the tests showed consistent formation of a. biofilm on the surface of the fibres. A cell stack design based on multiple pocket anodes containing the fuel sludge has also been demonstrated. (C) 2007 Society of Chemical Industry.