Comments on ‘Integration of the Clarification Process’: Joint Discussion

In this joint discussion, J. William Moffett states that historically, water treatment plant design has shifted from one unit operation to another as new developments become available. Recently, emphasis has shifted to the filter units, with many people feeling that the “superfilter” is the panacea for all problems and that the pretreatment section can be largely ignored. Moffett strongly disagrees with this approach and feels that the entire plant be considered. The modern water treatment plant must be an integrated unit with coagulation, flocculation, settling, filtration, and disinfection all receiving maximum attention. Gordon G. Robeck states that an integrated system operated properly with coagulants and where necessary, with filter aids, can produce water as good or better than that from a conventional system operated at two or three times the usual filtration rates.