Microbiological quality before and after nanofiltration

The authors investigated microbiological behavior of a distribution system supplied initially with biologically treated water and then with nanofilter ed water. Their purpose was to identify and evaluate the changes in microbi ological water quality attributable to modifications in water treatment at the plant. During the course of the study, all data from various indicators or, microbiological quality (i.e., heterotrophic plate counts, coliform en umeration, total direct counts, and fixed bacterial biomass) showed similar trends. Results indicated that the use of nanofiltration allows utilities to reduce chlorination of treated water and at least maintain or increase t he microbiological quality of distributed water for areas with high residen ce times.