Microbial fuel cells for detecting pollutant levels in wastewater have been developed by Korean scientists.

Hyung Joo Kim from Konkuk University, Seoul, and collaborators have developed fuel cells powered by bacteria for monitoring levels of toxins in water entering wastewater treatment plants.

Biological wastewater treatment plants rely on maintaining a carefully balanced mixture of bacteria and other organisms, said William Draper, an expert in environmental health from the Department of Health, California, US. He explained that effective methods are needed to monitor excessive levels of toxins in the water entering the plants so the organism balance can be maintained.

The bacteria in Kim's fuel cells convert biochemical energy into electrical energy by oxidizing organic matter in the water. The electric current is then detected by a potentiometer, explained Kim. The bacteria generate a constant electric current under standard water pollutant levels. When the toxin levels in the water increase, however, the microbes become less efficient and electricity generation is inhibited. Draper likened this monitoring concept to 'the miner's canary'.

Further work is needed before these fuel cells can replace existing methods, explained Kim. He said that detection limits and specificity to various toxins need to be found, as well as ensuring the microbe community won't adapt to changes in pollutant levels.

Nina Athey-Pollard