PARTICLE REMOVAL AND HEAD LOSS DEVELOPMENT IN BIOLOGICAL FILTERS

The physical performance of granular media filters was studied under p rechlorinated, backwash-chlorinated, and nonchlorinated conditions. Ov erall, biological filtration produced a high-quality water. Although e ffluent turbidities showed little difference between the performance o f biological filters and conventional prechlorinated filters, differen ces were shown with particle counts. Although prechlorination yielded slightly better net particle removal than biological filtration, the o verall order of magnitude and size range of particles removed was simi lar. Biological filtration also produced economical filter run times.