Upflow water filtration unit, test results.

ABSTRACT UPFLOW water filtration units effectively reduced the turbidity of raw surface water to acceptable levels when operated at the suggested design flow rate of 41 L/min-m2 (one gpm/ft2) using raw water with moderate or low turbidities (less than 80 NTU). The correct alum concentration added was necessary to the proper and ef-ficient operation of the units. Maintenance of the units requires little time but is very important for proper operation. Large (114 L, 30 gal) chemical stock solution tanks combined with adjustable rate feeder pumps made replacement of the chemical stock (alum and chlorine) solutions infrequent. The fre-quency of backflushing the system and replacing the filter material depend mainly on the amount of suspend-ed sediment in the raw water.