A novel biomonitoring system using microbial fuel cells

A novel biomonitoring system using microbial fuel cells for detecting the inflow of toxic substances into water systems has been developed for the purpose of on-site and on-line monitoring. The characteristics of electric current generation by electrochemically-active bacteria were conveniently monitored using a microbial fuel cell format and a computer-controlled potentiometer. When toxic substances (an organophosphorus compound, Pb, Hg, and PCBs) were added to the microbial fuel cell, rapid decreases in the current were observed. The inhibition ratios caused by inflow of these toxic substances (1 mg l⁻¹) were 61%, 46%, 28% and 38%, respectively, when compared to the control, and generally increased in proportion to the addition time and concentration of toxic substances. When real wastewater was applied from a local wastewater treatment plant, more significant current decreases and higher inhibition ratios were observed following the introduction of toxic substances than in the laboratory tests. For example, the inhibition ratio was 76% on addition of a 1 mg l⁻¹ Cd and 1 mg l⁻¹ Pb mixture. Application of the microbial fuel cell for pollutant biomonitoring is discussed.