AWWA JAW17237

Pilot-plant studies were undertaken to determine the efficiency of slow-rate sand filters in removing Giardia cysts. Other variables studied were turbidity, particles, total coliform bacteria, and standard plate count bacteria. These dependent variables were evaluated with respect to the influence of design and operating conditions such as hydraulic loading rate, the concentration of cysts, the concentration of bacteria, the biological maturity of sand in the filter bed, the age of the schmutzdecke, and temperature. The filters removed virtually one hundred percent of the Giardia cysts, ninety-six percent of the standard plate count bacteria, and ninety-eight percent of the particles. Because of the efficiency and the passive nature of slow-rate sand filtration, this technology is especially appropriate for small water systems. Includes 24 references ; tables ; figures.