Water quality monitoring

The National Academy of Engineering has identified “provide access to clean water” as one of fourteen “grand challenges” for engineering in the coming decades. The monitoring of water quality is important for providing safe and clean drinking water to the public. Conventional techniques for monitoring the water quality are commonly based on physicochemical analyses, allowing accurate and sensitive detection of the various chemical compounds. However, conventional monitoring techniques are time-consuming, cumbersome and require a wide range of instrumentation. Moreover, these techniques cannot measure synergistic and antagonistic toxic effects that may be associated with biological and chemical mixtures. Another approach for water quality monitoring is based on the use of living organisms such as fish, protozoans, algae, bivalves, and daphnids. This technique monitors a wide range of toxic components by detecting various changes in the behavior, survival, growth, or physiological conditions in those water organisms. However, it still suffers from evaluating the enormous amounts of information of continuously monitored organisms. Therefore, simple, fast, sensitive and generic biosensors are needed for real-time applications.

Microbial fuel cells (MFCs) can potentially be used as a biosensor for the detection of water toxicity because a broad range of toxic components can inhibit bacterial metabolic activity. MFCs are bioelectrochemical systems that produce a current through bacterial metabolism. Consequently, the current generated from the MFC can be used as a measure of the water quality because a change in electrical current depends on several environmental factors including pH, dissolved oxygen, biochemical oxygen demand, and other organic compounds. In particular, the presence of toxic substances in water, such as formaldehyde, benzene, hexane toluene and heavy metals, significantly affect the bacterial metabolism and growth. Therefore, if the current drop is monitored from the MFC biosensor, an alarm is given and proper measures can be taken to protect our waterways from pollution.