Control of fouling bacteria in freshwater used for the firewater system of a power plant by chemical biocides - an in vitro study

Biofouling/Biofilms create serious technical problems in industrial operations such as blockages in pipelines, impeding heat transfer process, biodeterioration of metals and polymeric components. In this study, the control of bacterial population in freshwater used for the firewater system of a power plant by chemical biocides was investigated. Additionally, the bacterial cultures isolated from the firewater were also tested. Two chemical biocides, Cetyl trimethylammonium bromide (CTAB) and glutaraldehyde were tested for anti-bacterial activity in laboratory experiments. The microtitre plate studies showed that CTAB was effective in low concentrations when compared to glutaraldehyde in microbicidal activity. However, as far as biofilm inhibition and disruption are concerned, glutaraldehyde was found to be more efficient. Although, the biocides showed 50% reduction in biofilm removal, the metabolic inhibition of the biofilm bacteria by MTT assay was found to be 100%. In case of the biofilms formed on carbon steel coupons, glutaraldehyde was found to be more efficient microbicide. While the use of biocides did not reduce the generalized corrosion, the localized pitting corrosion caused by fouling bacteria was effectively controlled.