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Water Supply Vol 2 No 3 pp 65–71 © IWA Publishing 2002

Using turbidity and particle counts to monitor Cryptosporidium removals by filters

P.M. Huck*, B.M. Coffey**, W.B. Anderson***, M.B. Emelko****, D.D. Maurizio*****, R.M. Slawson******, I.P. Douglas*******, S.Y. Jasim******** and C.R. O'Melia*********

*University of Waterloo, Department of Civil Engineering, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1
**Metropolitan Water District of Southern California, Water Quality Monitoring Section, 700 Moreno Avenue, La Verne, California, USA 91750
***University of Waterloo, Department of Civil Engineering, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1
****University of Waterloo, Department of Civil Engineering, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1
*****Metropolitan Water District of Southern California, Water Quality Monitoring Section, 700 Moreno Avenue, La Verne, California, USA 91750
******University of Waterloo, Department of Civil Engineering, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1
*******City of Ottawa, Water Division, 2731 Cassels Road, Ottawa, Ontario, Canada K2B 1A8
********Windsor Utilities Commission, Water Division, 4545 Rhodes Avenue, P.O. Box 1625 Station A, Windsor, Ontario, Canada N9A 5T7
*********The Johns Hopkins University, Department of Geography and Environmental Engineering, 3400 North Charles Street, Baltimore, Maryland, USA 21218


ABSTRACT
Physicochemical removal of protozoan pathogens is receiving increased attention because of the difficulty of chemically inactivating these organisms, particularly Cryptosporidium parvum. Most studies that have examined the removal of these and other pathogens by filtration have been conducted under steady-state conditions with optimized pre-treatment. The research on which this paper is based evaluated the removal of Cryptosporidium and surrogates at various points in the filter cycle and under non-optimal conditions, at several pilot plants. The focus of this paper is on the relationship between removals of Cryptosporidium, and turbidity and particle counts. Under stable or optimal operating conditions all pilot plants produced similar low filter effluent turbidity and particle counts. Average Cryptosporidium removal varied among locations, however, by more than two log units. Cryptosporidium removal was impaired under all of the non-optimal conditions. Particle and turbidity performance was also worse, but the relationship of these parameters to Cryptosporidium removal varied. Particle counts show greater promise than turbidity as a tool to monitor filter performance in real time for possible deterioration in Cryptosporidium removal capability.

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