MFCs have the potential to revolutionise wastewater treatment and catalyse a change in attitude towards wastewater as a commodity. It has been observed that domestic wastewater contains approximately 7.6 kJ/L of energy (Heidrich et al., 2011). In large-scale settings, wastewater could be used as an energy resource, offering huge savings in terms of cost and environmental burden. The major challenges facing the implementation of MFCs into wastewater treatment are scale up and energy harvesting/storage.
In this study, a modular 20L air-breathing microbial fuel cell was developed alongside a smart energy harvesting (EH) system incorporating AI. The 20L air breathing MFC consists of modular cathode cassettes that enables easy maintenance and scale up to suit adaptive or changing end user requirements. PVDF/Stainless steel mesh cathodes are fabricated using phase inversion and oxygen reduction reaction catalysts incorporated in the polymeric matrix. Custom made carbon fibre brush electrodes are utilised as anodes. The system was inoculated with Shewanella Oneidensis MR-1 and ran under recirculating batch conditions.
The MFC is monitored and controlled by a purpose-built circuit that tracks the performance of the individual cathode cassettes and configures the system via a custom Maximum Power Point Tracking (MPPT) algorithm for the best efficiency available for the given conditions. In addition, the circuit stores the extracted energy in a suitable energy storage element such as a capacitor bank or a rechargeable battery pack, with optimum charging levels. Moreover, the system is capable of learning multiple parameters associated with the MFC to optimise its parameters to maintain its high efficiency. The harvested energy can be used to power various types of electronic devices through the circuit's variable/adjustable power output.
Heidrich, E., Curtis, T. and Dolfing, J. (2011). Determination of the Internal Chemical Energy of Wastewater. Environmental Science & Technology, 45 (2), 827-832. Available from 10.1021/es103058w.