Brush Anode And Tubular Cathode Scale Up Microbial Fuel Cells.

Byline: Staff Writers

UNION TOWN, Pa., March 23 (SPX) -- A carbon fiber, bottle-brush anode developed by Penn State researchers will provide more than enough surface for bacteria to colonize, for the first time making it possible to use microbial fuel cells for large scale electricity production. In addition, a membrane-tube air cathode, adapted from existing wastewater treatment equipment, will complete the circuit.

"The carbon fiber brushes are electrically conducting, very inexpensive to produce and supply large surface area for the bacterial biofilm attachment," says Bruce E. Logan, the Kappe Professor of Environmental Engineering.

"These anodes can be made by any existing brush manufacturer in any size or shape desired."

Microbial fuel cells work through the action of bacteria, which can pass electrons to an anode of a fuel cell. The electrons flow from the anode through a wire to the cathode, producing an electric current. In the process, the bacteria consume organic matter in the wastewater and clean the water. The Penn State approach uses the bacteria that naturally occur in wastewater, requiring no special bacterial strains or unusual environmental demands.

Previously, Logan and his team showed that small, rectangular fuel cells that used a carbon fiber paper as anode and a carbon fiber paper with platinum catalyst as cathode could produce electricity and clean water from wastewater. However, commercial scale-up for carbon fiber paper cells was not practical.

Using brush anodes, which have 300 to 1,500 times more surface area than the previously used carbon paper anode, the fuel cells created more than twice the power produced by the fuel cells two years ago. A fuel cell using a small brush about 1 inch in diameter and 1 inch long produced the equivalent of 2.4 watts for every 260gallons of water using the carbon paper cathode, the researchers reported in today's (Mar 21) online edition of Environmental Science and Technology.