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The competitive pricing for seawater desalination, as demonstratedby recent privatized projects, has now made many coastal communities re-examine thepossibility of augmenting their water supply from the sea. The Bureau of Reclamationfunded a long-term pilot plant evaluation of membrane filtration and conventional mediafiltration technologies. This paper reports the results of the economic analysis performedfor this pilot evaluation and represents the only such evaluation to be conducted to date for aside-by-side comparison of pretreatment technologies evaluated in conjunction withdownstream RO units for open intake seawater systems.The principal purposes of this study were to:evaluate the performance of membrane pretreatment versus conventionalpretreatment for seawater reverse osmosis (SWRO) desalination, in terms of improvedpretreated water quality and impact on RO performance; and, evaluate the economics of SWRO desalination using membrane pretreatment orconventional pretreatment, through establishment of an objective life-cycle costcomparison. There were several specific objectives of the study. The first was tocompare differences in treated water quality between membrane pretreatmentand conventional media pretreatment. Evaluate turbidity, silt density indices (SDI), andmicrobiological counts to ascertain the effectiveness and limitations of the two differentpretreatment methods.Based on pilot testing information and observations, the second objective was to evaluate and determinedifferences between membrane filtration and conventional pretreatment with regard to theoverall operation and maintenance and performance of the RO system. Evaluate cleaningand maintenance requirements, pressure drops, permeate water quality, and other operationand maintenance differences.The third objective was to evaluate membrane filtration integrity over the term of the piloting test period todetermine its ability to fully act as the disinfection barrier for the RO process. Monitor biological growth and assess fouling impacts in the RO system throughout the evaluation andcompare it to the RO system operating on the conventional pretreatment system.The final objective was to, by using life-cycle economics, perform an objective cost comparison fordesalination plants using membrane pretreatment and conventional pretreatment. Several different membrane filtration technologies and conventional mediafiltration were evaluated at the pilot-scale as pretreatment to seawater RO. The conventionalmedia filter was composed of a single stage system using sand, anthracite and garnet. Theproject was implemented at the San Patricio Municipal Water District (SPMWD) watertreatment facility near Corpus Christi, Texas. The feedwater to the pilot plant was seawatertaken from the nearby Corpus Christi Bay, which is located in the northwestern area of theGulf of Mexico.The project was accomplished through two phases of piloting. The initial phase involvedoptimization of the membrane filtration and conventional pretreatment system. The secondphase of experimentation utilized the optimized membrane filtration and conventionalpretreatment systems providing pretreated feedwater to the SWRO pilot units. SeparateSWRO systems were used for each of the membranes filtered and conventional filteredpretreatment water throughout the study. Includes tables, figures.

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Edition: Vol. - No. Published: 03/01/2005 Number of Pages: 14File Size: 1 file , 410 KB