Long Term Field Testing of Floating Microbial Fuel Cells in Anoxic Wastewater of a Purification Plant

In the present study, we report different prototypes of floating MFCs that have been tested in anoxic wastewater environments of an Italian wastewater treatment plant, over a period of 3 years. Several configurations of horizontal (flat) and vertical (tubular) MFCs were assembled and tested, using low-cost and light-weight materials, such as plastic lunch boxes, polystyrene or wood to keep the systems afloat and ceramics. Untreated carbon cloth/veil was used for both the anode and cathode electrodes, and felt (flat MFCs) or clay (tubular MFCs) was used as the cation-exchange separator. Flat MFCs generated up to 15 mW/m2 of power, depending on nutrient availability in the water, whereas the cylindrical MFCs generated up to 18 mW/m2. The long-term operation did not affect the electrodes of the tested MFC systems. The cathode was the limiting electrode, sensitive to light, for the flat MFCs smaller than 50x50cm. In addition, a new and simple low-energy remote monitoring system, based on LoRa technology, was used for data transmission over distances of > 500 m. This is a piece of hardware that can potentially be used remotely in the field to create a sensing/monitoring network, as it can be directly powered by the deployed MFCs