Full Description

The application of low-pressure membrane filtration, including ultrafiltration and microfiltration, isincreasing exponentially in the United States mostly because of regulatory drivers and thedecreasing cost of this technology. As managers of water systems look at new water treatmentprojects or retrofit of existing treatment plants, membrane technologies are often consideredbecause they allow managers to meet more stringent microbial removal requirements while notcausing formation of byproducts that are also facing more stringent standards.Membrane filtration also offers some significant advantages over conventional treatmentprocesses. These advantages include a high level of automation, they require fewer operators,and consistently produce high quality filter water that is not sensitive to variation and feed waterconditions, or the manner in which the facility is operated.As a result, there has been tremendous growth in both the size and number of low-pressuremembrane filtration systems in the United States; from the first operating facility constructed inthe United States there was 100 gallons per minute (gpm) in 1993, to 1997 when there weremore than 10 operating facilities, the largest which was 7 million gallons per day (mgd), to theyear 2001 when there were over 60 operating facilities or facilities in design, the largest of which is24 mgd. Larger projects are currently being evaluated including one by the City of Minneapolis,Minnesota where a 70 mgd membrane filtration facility is proposed.Not only is there growth in the size of new facilities and the number of new facilities in theUnited States, but there is also tremendous growth in the diversity and number of availablemembrane products. At the time this manuscript was written there are over a dozencommercially available membrane products in the United States. Since the early 1990's whenthe available products were primarily designed for filtration of raw water supplies, the industryhas developed a wide range of low-pressure membrane systems each with its own set ofcompatibility and performance characteristics. The diversity of products today allows integration oflow-pressure technology into most processes used in drinking water treatment; coagulants, limesoftening, in-line addition of powered activated carbon (PAC) among others. This flexibility isdue to innovation in the design in membrane systems diversity in polymers used to construct themembrane fibers and the research and development efforts of various suppliers. Includes 2 references, tables, figures.

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Edition: Vol. - No. Published: 06/16/2002 Number of Pages: 14File Size: 1 file , 3.1 MB