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This paper explores the environmental, structural, work sequence, and operation considerations that have to beaddressed when installing a 14 million gallons per day (mgd) low-pressure membrane process (ultrafiltration) withinan existing water treatment plant (WTP) facility. To illustrate these considerations, the paper reviews the design thatwas performed for the rehabilitation of the existing WTP at the City of Lake Forest, Illinois.The City of Lake Forest WTP is a 12-mgd conventional granular media filtration process that uses Lake Michigan asraw water supply. The City of Lake Forest had concerns about the WTP's ability to meet existing and future waterquality standards at its design capacity and to expand its capacity within the limits of the constrained site. Therefore,the City of Lake Forest decided to proceed with the rehabilitation of the existing facility.After review of the process treatment alternatives and the site constraints, low-pressure membranes appeared to be aviable alternative. Therefore, the City of Lake Forest decided to proceed with the design of a new low-pressuremembrane filtration building.In order to minimize the project schedule, the first step of the design phase was to select the low-pressure membranesystem. In addition to the criteria typically used for membrane selection such as full-scale experience, membranecompatibility with process chemicals, membrane certification, operation mode, and integrity testing, it appeared thatinstallation criteria specific to the site had to be reviewed and evaluated.The main question raised during the membrane selection process was choosing between a pressure-driven system and asubmerged system. The following criteria were evaluated:membrane system energy cost;installation of the new membrane system into the existing filter cells;operation of the existing treatment process during construction;minimal environmental impact of the new structure;match floor elevation between existing building and new building;maximize re-use of the existing basins;preserve the future; and,present worth analysis.Finally, a pressure-driven system was selected to match the specific constraints of the City of Lake Forest. More andmore utilities are seriously considering rehabilitation of their existing facility with low-pressure membrane.Selecting the type of membrane system that addresses site and operation constraints is the key to a successfulrehabilitation project. As each site is unique, the results of one study cannot be generalized for other sites. However,the same approach can be used on multiple sites. Includes 2 references, tables.

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Edition: Vol. - No. Published: 06/15/2003 Number of Pages: 6File Size: 1 file , 250 KB