Thermal and chemical disinfection of water and biofilms: only a temporary effect in regard to the autochthonous bacteria

Abstract

Thermal and chemical disinfection of technical water systems not only aim at minimizing the level of undesired microorganisms, but also at preventing excessive biofouling, clogging and interference with diverse technical processes. Typically, treatment has to be repeated in certain time intervals, as the duration of the effect is limited. The transient effect of disinfection was demonstrated in this study applying different treatments to water and biofilms including heat, chlorination, a combination of hydrogen peroxide and peracetic acid and monochloramine. Despite the diverse treatments, the reduction in live bacteria was followed by regrowth in all cases, underlining the universal validity of this phenomenon. The study shows that autochthonous bacteria could reach the concentrations given prior to treatment. The reason is seen in the nutrient concentration that has not changed and that forms the basis for regrowth. Nutrients are released by disinfection from lysed cells or are still fixed in dead biomass that is subsequently scavenged by necrotrophic growth. Treatment cycles therefore only provide a transient reduction of water microbiology if nutrients are not removed. When aiming at greater sustainability of the effect, biocidal treatment has to be equally concerned about nutrient removal by subsequent cleaning procedures as about killing efficiency.

Sanitation Knowledge and Practices of Malaysian Food SMEs: Addressing Current Issues and Readiness in Acceptance of Green Sanitation Technology

“…They stated that hot water rinse could remove food soil (e.g., fat, oil stains) and eventually kill any microorganisms accumulated on foodcontact surfaces. Foodborne pathogens can be disinfected at high water temperatures without the help of cleaning chemicals [32][33][34]. Moreover, one of the respondents also added that hot water is essential to ensure cleaning chemicals react efficiently during cleaning.…”