Model systems were developed to evaluate microbial growth on surfaces and to determine the efficacy of biocides. Dynamic systems were used to simulate key operating parameters in industrial cooling towers. Biofouling was measured on wood, stainlessteel, and heat transfer surfaces. Biocide testing in these model systems showed that methylchloromethylisothiazolone was effective in controlling microbial growth in biofilms. The efficacy of the isothiazolone biocide was related to the treatment level and the nutrient content of the recirculating water.
Biofilm control was monitored using viable counts of microorganisms as well as measuring specific biomass components (protein and carbohydrate) on surfaces. An online fouling monitor (heat exchanger) confirmed that low biofilm growth correlated with low heat transferesistance.
Keywords:biofouling, biotihn,biocide, isothiazolone, cooling water, bacteria, heat exchange