Microbiologically Influenced corrosion (MIC) and microbiological fouling of piping and heat exchanger materials is a common and often costly problem in industrial cooling water and process water systems. MIC failures have caused expensive unplanned outages, the need for local repairs, and, in some cases, complete system replacement. The control of biofilm on surfaces has been shown to be the most effective tool for mitigating MIC as well as for maintaining heat transfer in heat exchangers. The most common method for control of microbiological fouling is the use of oxidizing biocides. Effluent limits and the corrosion penalties associated with their use drive users toward optimizing treatments in order to control biofilm effectively while meeting discharge limitations and without incurring excessive corrosion due to the treatment. Optimized treatments require accurate monitoring of biofilm activity. An electrochemical sensor has been developed to provide plant owners with a tool for monitoring biofilm activity on metallic surfaces - a useful method for predicting system conditions and for controlling biocide additions. The probe has recently been incorporated into a complete system that includes on-line data acquisition and data analysis capabilities. Those capabilities permit plant personnel to determine the presence and activity of biofilms on metal surfaces in their systems in real time; a powerful tool for optimization of biological controls. Results from these activities, using data from actual plant installations, are described, along with implementation strategies for the use of the
system to provide satisfactory microbiological control at the lowest cost.