Influence of nitrogen limitation on performance of a microbial fuel cell

Nitrogen limitation within biological wastewater treatment processes is a cause for concern in a number of large-scale industrial sectors. Microbial fuel cells (MFC) are an innovative technology with potential application within the wastewater treatment industry. Currently, little is known about the impact of nitrogen limitation on these systems. In this work we describe the operation of a microbial fuel cell system operating on a synthetic wastewater (acetic acid), under conditions of increasing nitrogen limitation.

Stable operation of the cell was observed under all conditions, with improved electrochemical performance (as power density) being noted as nitrogen limitation was imposed on a cell initially operated under conventional nitrogen/carbon ratio. Even under zero ammonium addition, continuous function of the cell was maintained, at levels consistent with operation at balanced nutrient supplementation.

The work has implicated biological nitrogen fixation as a potential source of nitrogen, within the MFC. This supposition has yet to be confirmed, a subject of ongoing work in our laboratories.

The work highlights the opportunity for continuous operation of a microbial fuel cells for wastewaters having extremely low nitrogen levels, such as is evidenced in forest indu stry, pharmaceuticals and petrochemical industries. Further, the indication of increases in some of the electrochemical indices (e.g. power density) under application of nitrogen limitation may provide a new approach to increasing fuel cell performance. Finally, the lack of any need to add supplemental nitrogen to a MFC-based wastewater treatment technology holds potential for significant cost and environmental savings.