Biofilm based sensors for environmental and industrial monitoring

The discharge of industrial and municipal wastewaters containing substances potentially harmful to aquatic ecosystems and human health represents one of the major problems connected to water management. The efforts towards this threat reduction must go hand in hand with the development of monitoring systems able to provide, on-line and in real time, an early-warning information about the presence of pollutants in the water. Starting from these considerations, the electrochemical activity of natural water biofilms, largely studied in the last 20 years, has been exploited to develop two different kinds of biosensors for industrial and environmental applications. In the first case, since large amounts of disinfectants and other chemical substances are employed in the water lines of industrial plants as a countermeasure against biofilm, aim of this research was to realize a sensor for bacterial growth monitoring, to optimize the above mentioned biofilm cleaning treatments. This optimization, indeed, entails a reduction of both costs and of biocide treatments environmental impact. In the second case, considering that the biofilm is a micro-ecosystem, the changes induced in its electrochemical activity by addition in water of toxic substances were studied, to realize a biosensor for water pollution, based on this phenomenon. Concerning the industrial application, it emerged that, adjusting biocide treatments basing on the real biofilm growth monitored by this sensor prototype, it was possible to drastically reduce the use of chemicals within industrial water lines. The biosensor for water pollution provided interesting results too; when different toxic substances were added to the water in which the biofilm was growing, the bacterial electrochemical signal was inhibited, and this inhibition was proportional to the concentration of the added toxic substance.