Perchlorate is an environmental contaminant whose occurrence is linked with its use
as an oxidant in rocket propellants and missiles. Exposure to perchlorate may cause
hypothyroidism by blocking the uptake of iodine in the thyroid gland. Upon the development of
sensitive analytical methodology using ion chromatography, perchlorate contamination in the
drinking 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 States
Environmental Protection Agency (U.S. EPA) formally added perchlorate to the drinking water
contaminant candidate list (CCL) in March 1998 and its monitoring in drinking water supplies was
mandated 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 µg/L,
perchlorate. Currently, the health and ecological risks resulting from perchlorate exposure are being
assessed 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 high
pressure membranes, two reverse osmosis (RO) and two nanofiltration (NF) membranes at the
operational variables of three levels of recovery, ranging from 15 to 50%; to monitor flux decline
as a consequence of scaling; and, to investigate the treatment of concentrated brine streams by the
chemical reduction and microbiological reduction. Perchlorate anion prepared with sodium perchlorate salt was measured on a
Dionex DX300 ion chromatograph with a IonPac AS11 column and 1000 µL injection loop. 100 mM
of NaOH as an eluent and 50 mN of H<sub>2</sub>SO<sub>4</sub> for chemical regenerant were employed. A guard
column (4 mm IonPac AG11) was used for reducing large matrix ion peak. This method showed
1.4 µg/L as a detection limit, based on detection by a conductivity CDM-2 detector. Other
anions were analyzed by a Dionex Series 4500i ion chromatograph and cation measurements
were 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 streaming
potential. For the water quality characterization of source water, several analyses including
ultraviolet absorbance at 254 nm (UV<sub>254</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 ranges
of 100~500 µg/L, to simulate membrane-treated brine was purged with nitrogen gas (N<sub>2</sub>) before
used in the experiment to provide anoxic condition with the dissolved oxygen levels lower than 1 %.
Concentrated sulfuric acid (H<sub>2</sub>SO<sub>4</sub>) was added to control the initial pH. The reduction was
monitored under various conditions. Tested factors include zero valent iron dose, reduced iron source forms, pH and the presence of catalyst. All the experiment was conducted
under ambient temperature and in a closed condition. Includes 12 references, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 650 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 13 |
| Published : | 03/01/2005 |
