AWWA JAW20090

Pilot-scale constant-rate and declining-rate direct filtration systems were evaluated for treating a high quality surface water, using two flow rates and alum or cationic polymers as the primary coagulant. Turbidity, particle count, and total coliform count were used to compare filtrate qualities. Effluent quality for the two filtration schemes was essentially identical, a result that disagrees with a previous study using lime-softened water in which a significant quality advantage in declining-rate over effluent-controlled constant rate filtration was determined. The rate of head loss increase was the same for both types of filters, a result which was consistent with conclusions of previous studies. It was concluded that in future studies, four constant rate filters (not one) should be compared with four declining-rate filters to provide a more direct and complete comparison of filtrate quality and operating characteristics. In addition, individual filters as well as combined filters should be monitored for each filter system. Includes 26 references, tables, figures.

Product Details

Edition:

Vol. 78 - No. 12

Published:

12/01/1986

Number of Pages:

9

File Size:

1 file , 2 MB