Stand-alone floating microbial fuel cell-based biosensor for tracking organic pollution influx

Organic wastewater discharge is an alarming issue with freshwater lakes and rivers. This research developed a self-powered stand-alone floating biosensor based on a microbial fuel cell (MFC) for early organic wastewater detection. The MFC case was fabricated by a 3D printer, and the electrodes were fabricated from low-cost carbon-based materials. Soil containing electrogenic bacteria was loaded on the anode to increase the sensitivity and stability of the biosensor. In this research, chemical oxygen demand (COD) was used to represent the organic content of water. Experimental data showed a linear relationship between the COD of water and the output voltage of the MFC. Moreover, an energy harvesting circuit equipped with a flashing light-emitting diode (LED) was powered by the MFC. The LED started to flash when the COD of water was about 60 mg/L, and the flashing pace increased as the COD increased. As a result, organic content in water could be detected by the device and visually represented through the flashing pace of the LED. This solution potentially enables a simple and low-cost measure for water quality control at the input of freshwater lakes and rivers.