Biofilm formation in the drinking water distribution system, on selected pipe materials in flow reactors – preliminary investigations

This study analysed the formation of biofilms in the drinking water distribution system in Wroclaw. The focus was on the influence of the material from which pipes in water distribution systems are built: polyethylene (PE) and polypropylene (PP). Two reactors with continuous water flow were used. Once the quasi- steady state was determined, an analysis was carried out to measure the total number of microorganisms per unit volume, which were stabilised without affecting further changes in concentration, and to study the basic physicochemical parameters of water that can affect the microbial growth that forms. In addition, a literature review was conducted to analyse biofilm formation based on physicochemical parameters in the water distribution system. Psychrophilic bacteria were shown to be more numerous than mesophilic bacteria, with the growth rate of the latter being higher. An increase in the number of microorganisms was observed, with higher concentrations found on PE surfaces because the rougher surface structure provides better adhesion for biofilm-forming microorganisms than on a surface made of polypropylene (PP). The presence of mesophilic bacteria may indicate the potential for pathogenic microorganisms, as well as the formation of a primary biofilm characterised by irreversible attachment to the substrate. These findings suggest that synthetic materials such as PE are more susceptible to biological growth than polypropylene (PP) as a result of their uneven surface structure, which facilitates the deposition of biofilm-forming organisms. The preliminary results can be used as an important reference for future research related to biofilms in drinking water distribution systems.