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Perchlorate is an environmental contaminant whose occurrence is linked with its useas an oxidant in rocket propellants and missiles. Exposure to perchlorate may causehypothyroidism by blocking the uptake of iodine in the thyroid gland. Upon the development ofsensitive analytical methodology using ion chromatography, perchlorate contamination in thedrinking water supplies of over 15 million people in California, Nevada and Arizona, and in groundwaters and surface waters throughout the 13 U.S. states has been discovered. The United StatesEnvironmental Protection Agency (U.S. EPA) formally added perchlorate to the drinking watercontaminant candidate list (CCL) in March 1998 and its monitoring in drinking water supplies wasmandated in 1999 under the Unregulated Contaminants Monitoring Rule (UCMR). In January 2002,the California Department of Health Services (DHS) lowered the perchlorate action level to 4 g/L,perchlorate. Currently, the health and ecological risks resulting from perchlorate exposure are beingassessed and the majority of research efforts for perchlorate treatability are actively ongoing. The objectives of this study were: to determine the removal/rejection of perchlorate by highpressure membranes, two reverse osmosis (RO) and two nanofiltration (NF) membranes at theoperational variables of three levels of recovery, ranging from 15 to 50%; to monitor flux declineas a consequence of scaling; and, to investigate the treatment of concentrated brine streams by thechemical reduction and microbiological reduction. Perchlorate anion prepared with sodium perchlorate salt was measured on aDionex DX300 ion chromatograph with a IonPac AS11 column and 1000 L injection loop. 100 mMof NaOH as an eluent and 50 mN of Hsub2/subSOsub4/sub for chemical regenerant were employed. A guardcolumn (4 mm IonPac AG11) was used for reducing large matrix ion peak. This method showed1.4 g/L as a detection limit, based on detection by a conductivity CDM-2 detector. Otheranions were analyzed by a Dionex Series 4500i ion chromatograph and cation measurementswere performed with the ICP-AES (ARL model 3410+). A commercial electrokinetic analyzer (EKA)was employed to estimate the zeta potential of membrane specimens by measuring the streamingpotential. For the water quality characterization of source water, several analyses includingultraviolet absorbance at 254 nm (UVsub254/sub), dissolved organic carbon (DOC), total dissolved solids(TDS) and turbidity were performed.For the chemical reductuion of brine stream, perchlorate solutions synthesized at the rangesof 100~500 g/L, to simulate membrane-treated brine was purged with nitrogen gas (Nsub2/sub) beforeused in the experiment to provide anoxic condition with the dissolved oxygen levels lower than 1 %.Concentrated sulfuric acid (Hsub2/subSOsub4/sub) was added to control the initial pH. The reduction wasmonitored under various conditions. Tested factors include zero valent iron dose, reduced iron source forms, pH and the presence of catalyst. All the experiment was conductedunder ambient temperature and in a closed condition. Includes 12 references, tables, figures.

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Edition: Vol. - No. Published: 03/01/2005 Number of Pages: 13File Size: 1 file , 650 KB