Controlling biofilm growth in drinking and wastewater pipelines has attracted considerable scientific and technological attention over recent years. In this work, we have examined the biofilm control effectivity of a combined disinfectant comprised of hydrogen peroxide and silver ions. The performance of the combined disinfectant was compared to the effectivity of each of the ingredients alone and to the effectivity of chlorine disinfectant. Biofilm growth was investigated on uncoated and CaCO3 coated galvanized iron samples over prolonged exposure duration. It was found that the CaCO3 film does not significantly affect biofilm development. A combination of hydrogen peroxide and silver ions (30 ppm hydrogen peroxide and 30 ppb silver ions) were as effective in preventing film growth as hydrogen peroxide alone (30 ppm). Both compositions showed significant biofilm prevention effectivity as compared to silver ions alone. Biofilm prevention effectivity of chlorine (approximately 1 ppm) was considerably higher than that of the combined disinfectant. The bacteria that survived after 48 hours disinfection with hydrogen peroxide and the combined disinfectant showed high catalase activity hinting that hydrogen peroxide and the combined disinfectant may have a rather limited effectivity in continuous operation.

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