A bacterial fuel cell including at least one anode and at least two cathodes in liquid communication with a liquid to be treated, the at least one anode being separated from the at least two cathodes by at least first and second electrically insulating spacers and the at least one anode and the at least two cathodes being electrically connected across an external load and the at least one anode and the at least two cathodes being wound together generally in a spiral configuration together with at least a third electrically insulating spacer.