High-Rate Water Treatment: The State-of-the-Art

The results of a study conducted by the ASCE-EED Committee on Water Purification aimed at determining the prevailing concept of high-rate water treatment are presented. A survey of state regulatory agencies gained information in terms of attitudes and policies. In addition, an analysis of operating data from several high-rate water treatment plants in Virginia was conducted. Specific data are given for acceptable flash mixing, flocculation and sedimentation retention times, and for hydraulic loading rates of sand and multimedia filtration systems. The possible requirement of polymer feed capability and special process control equipment in high-rate filtration installations is considered. A total of over 200 plants operating at filtration rates in excess of 3 gpm/sq ft were identified. The economic advantages inherent in these processes make it incumbent on the design engineer to thoroughly evaluate their applicability in any situation.