Performance of a dual-chamber microbial fuel cell as biosensor for on-line measuring ammonium nitrogen in synthetic municipal wastewater

Highlights: • Ammonium detection in wastewater is well achieved by a dual chamber MFC biosensor. • Relation between NH₄⁺ concentration and voltage generation was inversely linear. • The dual chamber MFC biosensor could detect up to 40 mg L⁻¹ of NH₄⁺-N. • Excess ammonium inhibits the activity of electrogenic bacteria in the anode chamber. • Optimal operating conditions for the MFC biosensor are pH 7, 1000 Ω and 24-h HRT. This study investigates the performance of microbial fuel cells (MFC) for on-line monitoring ammonium (NH₄⁺-N) in municipal wastewater. A double chamber microbial fuel cell (MFC) was established in a continuous mode under different influent ammonium concentrations ranging from 5 to 40 mg L⁻¹. Results indicated that excess ammonium would inhibit the activity of electrogenic bacteria in the anode chamber and consequently affect electricity production. An inversely linear relationship between concentration and voltage generation was obtained with coefficient R² 0.99 and the MFC could detect up to 40 mg L⁻¹ of NH₄⁺-N. Notably, no further decline was observed in voltage output and there was in fact a further increase in ammonia concentration (>40 mg L⁻¹). The stability and high accuracy of ammonium-based MFC biosensors exposed competitive results compared to traditional analytical tools, confirming the biosensor's reliability. Furthermore, pH 7.0; R 1000 Ω and HRT of 24 h are the best possible conditions for the MFC biosensor for monitoring ammonium. The simplicity in design and operation makes the biosensor more realistic for practical application.