| Affiliation: | (1) Laboratory of Environmental Microbiology, National Public Health Institute, P.O. Box 95, Kuopio, 70701, Finland;(2) Division of Water Supply and Sewerage, Faculty of Civil Engineering, Riga Technical University, Azenes Street 16, 1048 Riga, Latvia;(3) Laboratory of Chemistry, National Public Health Institute, P.O. Box 95, Kuopio, 70701, Finland;(4) Department of Environmental Sciences, University of Kuopio, Bioteknia 2, P.O. Box 1627, Kuopio, 70211, Finland |
| Abstract: | The formation of biofilms in drinking water distribution networks is a significant technical, aesthetic and hygienic problem. In this study, the effects of assimilable organic carbon, microbially available phosphorus (MAP), residual chlorine, temperature and corrosion products on the formation of biofilms were studied in two full-scale water supply systems in Finland and Latvia. Biofilm collectors consisting of polyvinyl chloride pipes were installed in several waterworks and distribution networks, which were supplied with chemically precipitated surface waters and groundwater from different sources. During a 1-year study, the biofilm density was measured by heterotrophic plate counts on R2A-agar, acridine orange direct counting and ATP-analyses. A moderate level of residual chorine decreased biofilm density, whereas an increase of MAP in water and accumulated cast iron corrosion products significantly increased biofilm density. This work confirms, in a full-scale distribution system in Finland and Latvia, our earlier in vitro finding that biofilm formation is affected by the availability of phosphorus in drinking water. |
