Low-pressure membrane systems depend on an automated backwashprocess to dislodge particulate build-up on the membrane surface.Although membrane manufacturers have different backwashprocedures and intervals, all utilities are faced with disposal of thiswater. In many cases this backwash water can be re-treated through aseparate membrane system to produce an effluent quality equal to thatof the primary system. Additionally, by adding a secondary treatmentsystem, the overall plant effectiveness is increased and costs fordisposing backwash water are reduced.California's Department of Health Services (DHS) currently does nothave regulations for processing membrane backwash water and relieson conventional treatment system criteria. The membrane processused at Carmichael Water District (CWD) does not require chemicaladdition to aid in filtration, which greatly differs from that found inconventional processes and permits re-treatment options.In June 2001, CWD embarked upon a program to demonstrate theviability of its treated backwash water as acceptable drinking water andaid the local regulatory agency in their decision to consider secondaryfiltrate for potable use.This paper examines the relationships of finished water qualityparameters for the primary and secondary stage filtration under fullscaleoperational conditions. Includes 6 references, tables, figure.
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Edition: Vol. - No. Published: 03/05/2003 Number of Pages: 7File Size: 1 file , 200 KB