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A two-month comparative pilot study was conducted to determine which submerged membranewould perform best for Kennewick's Water Filtration Plant (WFP) retrofit, how it should be configured, installationrequirements, and to develop specific criteria to be used in the membrane procurement process.The most important issue to be resolved was whether pretreatment would be necessary, orbeneficial, to the membrane operation.USFilter and Zenon are the only major manufacturers that offer low-pressure, submergedmembranes. Both are relatively new to the membrane market, and there are few full-scaleinstallations in the United States. Membranes from both companies were tested in this pilot studyin an integrated pretreatment process, including coagulation followed by a plate settler. Settledwater was fed into two submerged membrane units in parallel. After the first two months ofparallel testing, the USFilter membrane was tested for another six months in direct filtration modeto asses the feasibility of operating without any pretreatment. In subsequent phases, small dosesof coagulant and powdered activated carbon (PAC) were added inline to optimize organics removal.Overall, this study demonstrated that the new submerged membranes currently on the market areboth robust and flexible.This paper provides valuable information on membrane performance and compares finishedwater quality characteristics for different treatment schemes, including direct filtration (nopretreatment) with a combination of various coagulant and PAC dosages. This paper alsodiscusses membrane unit response when a short, but high spike of coagulated ferric flocs wasaccidentally released from the plate settler due to a chemical feed pump failure. Although thisevent was unplanned, it represents a realistic scenario which treatment plants should beprepared to handle and for which design criteria need to be developed. A set of pilot-studyguidelines is provided for utilities considering the membrane retrofit option. Includes tables, figures.

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Edition: Vol. - No. Published: 03/01/2005 Number of Pages: 19File Size: 1 file , 890 KB