Biological Stability of Drinking Water Through Ozonation at the Croton Water Supply in New York City. Desalination and Water Purification Research and Development Program Report No. 75; Final rept. for Oct 95-Apr 97

摘要

The effect of ozonation (a disinfection technology widely used in Europe and steadily gaining ground in the United States) followed by diatomaceous earth filtration (DEF) on post-disinfection bacterial regrowth potential of drinking water was investigated for the Croton water supply of New York City. Bacterial regrowth is a phenomenon that occurs following disinfection and within the distribution system independent of size. Waters that do not contain the necessary nutrients and cannot support bacterial growth have low bacterial regrowth potential, while waters that support post disinfection growth have high regrowth potential. Biostability was evaluated using the attached growth rate estimate (AGRE) method which measures growth rates of attached bacterial cells rather than using liquid phase procedures commonly employed. Factors that could not be fully explained in the experiments carried out in this study influenced filtration to produce finished water of highly variable quality. Biological filtration or other similar processes appear necessary to reduce the biological regrowth potential of the DEF effluent and avoid expected problems in the distribution system.