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Item Description Oki, Delwyn S. en_US Dugan, Gordon L. en_US Fujioka, Roger S. en_US Gee, Henry K. en_US Lau, L. Stephen en_US Takei, Gerald S. en_US 2008-10-16T01:52:38Z 2008-10-16T01:52:38Z 1994-07 en_US
dc.identifier.citation Oki DS, Dugan GL, Fujioka RS, Gee HK, Lau LS, Takei GS. 1994. Extending the effective life of the GAC used to treat well water: Phase I of evaluative study at Mililani. Honolulu (HI): Water Resources Research Center, University of Hawaii at Manoa. WRRC project report, 95-02. en_US
dc.description.abstract During 1986 and 1987, the City and County of Honolulu Board of Water Supply (BWS) placed granular activated carbon (GAC) water treatment plants in service at Mililani, Waipahu, and Kunia on the island of O'ahu, Hawai'i. The GAC treatment plants were designed to remove target organic chemicals DBCP, EDB, and TCP from well water in central O'ahu. Original operational cost estimates for the GAC treatment plants were based on carbon requirements determined through laboratory minicolumn experiments. Actual carbon usage rates, however, have proved to be several times higher than originally estimated. This study, which represents the first phase of a two-phase study to determine the potential for extending the effective life of GAC used to remove target organic chemicals from groundwater in central O'ahu, addresses the basic information necessary to understand the problem. Levels of target organic compounds in groundwater in the Pearl Harbor aquifer of central O’ahu do not appear to be decreasing significantly. In fact, based on the analysis of spent GAC samples from contactors at the Waipahu treatment facility, DBCP, which was previously undetected at the Waipahu wells, now appears to be occurring at low levels of a few nanograms per liter in groundwater near Waipahu. Analyses of spent carbon samples also indicate that the adsorptive capacity of the GAC for a particular compound is directly related to the concentration of that compound in the influent water. Total organic carbon (TOC) levels in groundwater samples from the Pearl Harbor basaltic aquifer are typically a few tenths of a milligram per liter. This concentration of background organics is two to three orders of magnitude greater than TCP, which is the target organic compound typically found at the highest concentrations in groundwater in the study area. TOC and infrared analyses indicate the presence of background organic compounds in groundwater, a factor which could shorten the service life of GAC contactors. Results of this study seem to indicate that inorganic cations and anions are not significantly adsorbed by the GAC. In addition to chemical effects, bacterial growth may also play a role in the adsorption of target organic compounds. Although -attached bacteria were recovered from spent GAC samples, subsequent scanning electron microscope analysis did not reveal a significant biological slime layer which may inhibit adsorption. en_US
dc.description.sponsorship Board of Water Supply City and County of Honolulu Grant/Contract No. C62830 en_US
dc.format.extent ix + 65 pages en_US
dc.language.iso en-US en_US
dc.publisher Water Resources Research Center, University of Hawaii at Manoa en_US
dc.relation.ispartofseries WRRC Project Reports en_US
dc.relation.ispartofseries 95-02 en_US
dc.subject water treatment en_US
dc.subject carbon filters en_US
dc.subject organic pesticides en_US
dc.subject contamination en_US
dc.subject well water en_US
dc.subject atomic absorption en_US
dc.subject spectrophotometry en_US
dc.subject gas chromatography en_US
dc.subject mass spectrometry en_US
dc.subject granular activated carbon en_US
dc.subject minicolumn carbon analysis en_US
dc.subject EDB en_US
dc.subject DBCP en_US
dc.subject TCP en_US
dc.subject GAC treatment facilities en_US
dc.subject Mililani wells en_US
dc.subject Pearl Harbor aquifer en_US
dc.subject central Oahu en_US
dc.subject Hawaii en_US
dc.subject.lcsh Carbon, Activated. en_US
dc.subject.lcsh Mililani (Hawaii) en_US
dc.subject.lcsh Water -- Purification -- Adsorption -- Hawaii -- Oahu. en_US
dc.subject.lcsh Water quality management -- Hawaii -- Oahu. en_US
dc.title WRRCPR No.95-02 Extending the Effective Life of the GAC Used to Treat Well Water: Phase I of Evaluative at Mililani en_US
dc.type Report en_US
dc.type.dcmi Text en_US

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