Study of biofilm associated bacteria on polyvinyl chloride, stainless steel and glass surfaces in a model cooling tower system with different microbiological methods

Cooling towers are an integral part of large range of industrial processes. The conditions of cooling water systems provide an ideal environment for microbial growth and biofilm formation. Microorganisms which enter via makeup water or air to the system form a biofilm layer on the inside surfaces of cooling tower which contain water and limited nutrients. Biofilm formation in cooling tower systems is undesirable for operational and public health reasons. Thus, microbial load should be monitored and kept under control. In this study, bulk water and biofilm associated microbial load were analyzed in terms of heterotrophic plate count (HPC), epifluorescence microscopy, carbohydrate quantity, total and free ATP concentration and compared material dependence. Kruskal-Wallis statistical analysis revealed that there were not significant differences between the tested slide materials according to HPC, DAPI-CTC staining, and ATP measurement. The ATP measurement together with fluorescence staining rei¬‚ected the changes in the bioi¬lms more distinctly than the HPC.