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The Long Beach Water Department (LBWD) is researching a subsurface intake system (under-ocean floor seawater intake) thatcollects seawater filtered through engineered sand beds at slow rates. The primary goal ofthis project is to determine if the system can deliver a sustained quantity of water. Asecondary goal is to deliver a consistent water quality that can be used as feed water fordesalination membranes. This research also tests concentrate discharge to minimizelocalized environmental effects, and evaluates additional potential benefit of reducingpretreatment processes. The tests are being conducted over 15 months to evaluate differences in influent waterqualities at filtration rates ranging from 0.05 to 0.2 gpm/ftsup2/sup. Two tests have been completed todate, and show that infiltration rates of 0.05 and 0.1 gpm/ftsup2/sup yield flows that are independentof the tide level (except in extreme low tidal conditions). Testing is ongoing to ensure therespective water quality goals of 3.0 SDIsub15/sub and turbidity 0.1 NTU are achieved by cartridgefiltration. These goals are generally accepted guidelines for influent water quality used withdesalting membranes.The water quality comparisons include chemical analyses (general, physical, selectedinorganic and organic), and specialized indicators of marine life activity (marine heterotrophicplate count-mHPC, adenosine triphosphate-ATP, assimilable organic carbon-AOC anddissolved organic carbon-DOC). The comparison will help direct the final stages of testing tohelp identify any gaps or validate the current test plan. This paper presents the results ofthe side-by-side comparison for the demonstration-scale experiments described above. Includes 5 references, table, figures.

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Edition: Vol. - No. Published: 11/01/2009 Number of Pages: 13File Size: 1 file , 1.4 MB