AWWA ACE93185

This paper describes the procedures and results of a process treatment investigation comparing the performance of dissolved air flotation (DAF) and direct filtration on a high quality water supply. The objectives of the pilot testing included determining the operational and performance characteristics of selected treatment processes during testing, unit hydraulic loading rates, chemical feed requirements, and operating conditions. The pilot testing also sought to determine the most effective treatment requirements of the Surface Water Treatment Rule, and other federal and state drinking water standards. Specific objectives of the pilot testing included meeting the minimal operational requirements for finished water turbidity, filter loading rates, filter run time, and unit filter run volumes. DAF routinely outperformed direct filtration with respect to finished water quality, filter production, and organics removal. Direct filtration was able to meet most of the pilot treatment criteria except when filter clogging algae were present in the raw water. DAF offered more process flexibility than direct filtration to meet future treatment regulations, and more operational flexibility with respect to filter clogging algae and coagulant selection.