Effective management and operation of coagulation and filtration

The most commonly used water filtration technique involves coagulation and rapid rate filtration, either in conventional plants with flocculation and sedimentation, or in direct filtration plants in which the sedimentation pr ocess is omitted. Both versions of coagulation and filtration can be effect ive for controlling Giardia cysts and Cryptosporidium oocysts, but research done by several investigators has shown that coagulation and filtration mu st be operated very carefully to attain the best results. When filtered wat er turbidity is 0.1 ntu or lower, the process is most effective. Careful co ntrol of coagulation chemistry and of filtration rate increases, continuous monitoring of filtered water turbidity, and proper management of backwash water are keys to successful filtration.