Uranium is a silver colored metal that is radioactive and can be found in soil, rocks, and water. Uranium is present in the environment as a result of leaching from natural deposits, release in mill tailings, emissions from the nuclear industry, the combustion of coal and other fuels and the use of phosphate fertilizers that contain uranium.
Uranium is found in the environment as a result of leeching from natural deposits, emissions from the nuclear industry, the combustion of coal and other fuels and the use of phosphate fertilizers that contain uranium. According to a University of Nebraska Lincoln study, 78% of the uranium-contaminated sites are linked to the presence of nitrate, which through a series of reactions oxidizes uranium making it more soluble and capable of finding its way into groundwater.
Uranium in drinking water is a concern for many people throughout the world. In the U.S. it is frequently found in the Midwest and Western United States; but it is also found in drinking water on the east coast and at various locations throughout the country. Drinking water is not the only exposure risk; eating root vegetables grown with contaminated water may also be harmful.
Uranium is not a proven carcinogen but accumulates in the bones similar to the way radium does. Therefore, the U.S. Environmental Protection Agency (EPA) tends to classify it as a carcinogen and states: “Intakes of uranium exceeding EPA standards can lead to increased cancer risk, liver damage, or both.” Uranium exposure has been found to have a toxic effect on human kidneys and animal studies indicate that uranium is absorbed into the muscles, skeleton, blood, lungs, and liver as well. Researchers at the University of New Mexico and Tufts report that there can also be long term genetic and reproductive damage from extended exposure to uranium.
Treatment of Uranium
Uranium can be reduced by both cation and anion dependent upon its state. Reverse osmosis will reduce uranium by 95 to 98%. Ultrafiltration will also reduce the amount of uranium. Activated alumina can also be utilized.
The U.S. Environmental Protection Agency (EPA) recommends reverse osmosis water treatment for most kinds of radioactive particles including uranium, radium, gross alpha, and beta particles and photon emitters. It can remove up to 99 percent of these radionuclides, as well as many other contaminants (e.g., arsenic, nitrate, and microbial contaminants). The World Health Organization reports that reverse osmosis treatment will remove 90-99 percent of uranium.
Reverse Osmosis is a process that filters most impurities from water by using a high-pressure pump to force water through a semi-permeable membrane to remove ions, molecules, and large particles from drinking water. It works by forcing water through a material with very tiny pores – as tiny as .0001 microns – so that almost nothing except water emerges on the other side. Contaminants such as uranium are left behind on the membrane while treated water passes through.
Unfortunately, it will not remove some pesticides, solvents and volatile organic chemicals including chlorine and radon. Dissolved gases and materials that readily turn into gases also can easily pass through most reverse osmosis membranes . For this reason, many reverse osmosis units have an activated carbon unit to remove or reduce the concentration of most organic compounds. And, in some cases, you may need to install a pre-filter before the reverse osmosis system.
A point-of-use reverse osmosis system will typically produce about 7 to 14 gallons a day of drinkable water. This amount of production should meet the cooking and drinking needs of a typical household. According to the Western Upper Peninsula Health Department: “To fix a uranium or radium problem, it is necessary only to treat the water you drink because uranium gets into the body through ingestion. It is safe to take baths using untreated water because uranium or radium is not absorbed through your skin.”
Point of use devices and systems currently on the market may differ widely in their effectiveness in treating specific contaminants and performance may vary from application to application. Therefore, selection of a particular device or system for uranium reduction should be made only after a careful investigation of its performance capabilities based on results from equipment validation testing for the specific contaminant to be reduced. After installation, periodic testing by an accredited laboratory should be conducted on both the water entering a treatment device and the water it produces to ensure the device is reducing the uranium concentrations to below 0.03 mg/L. A total dissolved solids (TDS) meter can provide these checks and can be a permanent part of the system.
The average price for a point-of-use system is $150-$300 (fixr.com) but they can cost up to $1,000 on the high end. A system typically costs around $300 and you can save money by doing the installation yourself. A whole-house sysem averages $2,000 but can cost up to $5,000.
Pros: It can filter lots of water. Removes viruses, most kinds of radioactive particles including uranium, radium, gross alpha, and beta particles and photon emitters (it can remove up to 99 percent of these radionuclides, as well as many other contaminants, e.g., arsenic, nitrate, bennzene, fluroide, lead, merrcury and microbial contaminants). Can be used to make sea water drinkable. Reverse osmosis units can be automated and compact making them appropriate for small systems. Produces best tasting water.
Cons: Purified water comes from a separate tap that may not be clean, removes nutrient minerals from the water, filters must be replaced regularly. Uses approximately three times as much water as it treats, requires adequate water pressure.
Carbon Filters are made from activated carbon and their primary function is the chemical absorptoin of contaminants and impurieties. An activated carbon filter has a pore structure that provides for particulate removal as well. Activated carbon works by absorbing contaminants and fixing them as water passes through it. The disadvantage to an activated filter is that it eventually reaches a load capacity and ceases to absorb new contaminants.
Pros: Easy to install, remove contaminants including benzene, chlorinem pesticides and rust, removes bad tastes and odors.
Cons: Expensive, filters must be replaced regularly, doesn’t remove fluoride. Average price $200-$300 (fixr.com).
Ion Exchange systems are also recommended by the EPA for removing radioactive compounds from drinking water. Ion exchange is a method of water purification that exchanges the ions of dissolved contaminants for similaryly charged ions of more neutral substances. More specifically, ion exchange removes contaminants when water passes through resins that contain sodium ions.
Ion exchange is particularly recommended for removing Cesium-137, which has been found in rain samples in the U.S., but not yet in drinking water here. Some resins have been specifically designed for capturing Cesium-137, and ion exchange was used to clean up legacy nuclear waste from an old reactor at the Department of Energy’s Savannah River Site (pdf).
Pros: Removes dissolved inorganics effectively, inexpensive.
Cons: Purification process isn’t as effective. Average price $50 (fixr.com).
Steam Distillation is another method that can be used to remove most of the uranium in your water. It will also remove some other contaminates such as arsenic and nitrates. A distillation system works by boiling water into water vapor, then returning it to its liquid state (duplicating nature’s cycle of evaporation condensation and precipatation). The minerals and contaminants such as uranium form scales and are trapped in the boiling chamber. The condensed water is collected in a storage container for consumption.
Pros: Can remove algae, bacteria, radioactive cesium, copper, pathogens, salt, sulfates and viruses. Wastes virtually no water in the process. Easy to install. Best tasting water. No water filters required.
Cons: The boiling chamber must be cleaned regularly to remove contaminants. The average cost of a 5 to 15 gallon storage tank is between $2,000 and $3,000; however, there are no annual filter replacement requirements.
Ratiation Threat
In the case of radiation contamination associated with Iodine-131 (a major fission product of uranium and plutonium mostly associated with nuclear reactors), the best solution may be the one used routinely to treat water at the Savannah River Site. The process combines activated carbon, reverse osmosis, and ion exchange. If one doesn’t get the iodine-131, two others have a chance to capture the radiation through other means.
Radiation Filtration Methods
Some reverse osmosis units include all three of these processes: carbon, reverse osmosis, and ion exchange. They are the most effective systems available to not only protect from radioactive particles but also fluoride, heavy metals, pesticides and many other contaminants.
Testing
If you plan to use any of these methods as a treatment for your drinking water, it is advisable to test the system after it is in place to be sure that it is removing radioactivity and other chemicals. This means testing water before and after you have installed the system.
Based on results of uranium monitoring since 2003, the analytical result of a single uranium sample is adequate to determine the degree of seriousness associated with the uranium level in well water. Uranium mass analysis is the appropriate water quality test to determine the level of uranium concentration in a water supply system. The fee for a uranium mass test typically ranges between $10 to $25. Tests to determine the presence of uranium in drinking water should be done by a laboratory certified for uranium testing. Not all laboratories are certified to test for all drinking water contaminants. Rather, certification must be obtained for each specific contaminant.
FAQS:
Uranium is a naturally occurring radionuclide. Natural uranium combines uranium 234, uranium 235, and uranium 238; however, uranium 238 makes up 99.27 percent of the composition. All radionuclides are considered carcinogens; however, each attacks organs differently.
Under the NIPDWR (national interim primary drinking water regulations), the MCL (maximum contamination level) for uranium is set at 15 pCi/L (see “Radium” for explanation of how radiation is measured).
Point of use reverse osmosis systems are available from a variety of different sources, and it is recommended that you purchase a unit which is “NSF certified for radium 226/228 reduction”. (NSF does not offer a uranium certification.) For more information, please visit the NSF website.
Sources:
- U.S. Environmental Protection Agency, National Service Center for Environmental Publications: Methods of Removing Uranium from Drinking Water : 1. A Literature Survey. 2. Present Municipal Water Treatment and Potential Removal Methods.”
- World Health Organization: “Uranium in Drinking-water, Background document for development of WHO Guidelines for Drinking-water Quality” updated June 2005.
- How to Remove Radioactive Iodine-131 From Drinking Water by Jeff McMahon
- Western Upper Peninsula Health Department, Environmental Health, Water Supply Protection Well Program: “What You Need to Know About Uranium in Private Well Water”
- University of Nebraska – Lincoln Extension, Institute of Agriculture and Natural Resources
- Wikipedia: Reverse osmosis,
- Wikipedia: Carbon filtering
- Wikipedia: Ion exchange
- MyAquanui: Uranium in Drinking Water
- Homeadvisor.com Install a Water Treatment and Purification System
