Desalination, from Rich Bubb

February 19, 2007 |

Some Specs have been discussing water-related investment opportunities. This article describes a working desalination pilot plant in Long Beach, CA.The use of nano-filtration is described, and the method is discussed in an overview manner. Unfortunately, the online article does not include the diagrams and illustrations in the print version of the article that appears in the February 2007 Water Technology magazine.

Following is intro to the article:

The Long Beach Water Department (LBWD) has developed and patented a two-pass nanofiltration (NF) process, called NF/NF, to desalinate seawater to drinking water. Over the past several years, the LBWD has been testing the hybrid desalination process in the 9,000-gallon-per-day (gpd) pilot scale unit at its groundwater treatment plant. The two-pass, multistage nanofiltration membrane process can treat water at a lower operating pressure and energy than a conventional, single-pass seawater reverse osmosis (SWRO) desalination process that uses cellulose acetate or thin-film composite membranes. A key component is the second-pass concentrate recycle loop, which dilutes the feedwater and makes the use of nanofiltration membranes feasible. LBWD has constructed a 300,000-gpd prototype seawater desalination facility to validate the performance results observed during initial pilot testing, and to test the long-term operating characteristics of the hybrid desalination process. 





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