Control of Cryptosporidium: From reservoirs to clarifiers to filters

摘要

Control of Cryptosporidium in potable waters requires an integrated multiple barrier approach of source water protection of water supply reservoirs and treatment technology through clarification, filtration, and disinfection. Pristine lakes and protected reservoirs have far lower concentrations of oocysts (mean values less than 10 oocysts/100 L) than unprotected supplies. Coagulation is critical to the effective control of Cryptosporidium by clarification and filtration. Coagulation conditions that produce filtered waters of low turbidities, particle counts, and effectively remove natural organic matter also produce high removals of Cryptosporidium. Dissolved air flotation (DAF) can achieve oocyst removals of 3 log compared to about 1 log by sedimentation. DAF and filtration provide two effective barriers to Cryptosporidium with cumulative log removals of 4 to 5 compared to log removals of 3 to 4 by sedimentation and filtration. (C) 1998 IAWQ. Published by Elsevier Science Ltd. [References: 17]