Radium is a radionuclide element in the second period of the periodic table and has similar physical and chemical characteristics to Calcium. Radium takes the form of a cation in water and is a naturally occurring contaminant associated with certain rocks and minerals. Radionuclide contamination of groundwater is generally attributed to sources naturally occurring in rock formations where wells are drilled. Radionuclides are a family of unstable compounds that continually emit energy in the form of radiation. Radionuclides include uranium, radium, radon and a family of compounds known as “gross alpha emitters” – any of which may require treatment.
WETS utilize dual media filtration system and coagulation and flocculation to treat radium. WETS also utilize cation exchange softening.
Hardness is not a regulated contaminant or water quality, but rather a subjective characteristic of water as it relates to washing, laundering, and its use in industrial cooling. Hard waters are said to be those that require large amounts of soaps or detergents in order to form a lather and be effective as a cleaning agent. Hard waters also tend to be scale-forming when used as coolant in heat exchangers.
Chemically, hardness is caused by a group of several significant divalent cations naturally found in water; hardness varies considerably depending on the geology of a region. In general, surface waters are softer than groundwaters. The significant hardness-causing divalent cations include: calcium, magnesium, strontium, iron and manganese.
Uranium is a naturally occurring metallic element found in certain groundwaters. Most uranium found in nature and associated with groundwater is in the form of uranium isotope 238. This form of uranium breaks down (decays) slowly into daughter products, radium and radon gas. Uranium is significant for designs because it is regulated at 30 µg/l for potable water and exists as an oxyanion when dissolved in water.
The most cost-efficient technology for uranium removal is the strong base anion exchange process. Typically waters having uranium contain less than 100µg/l. Anion resins have a high affinity for removal, so uranium removal treatment intervals can be long prior to regeneration being required.
Reverse osmosis membrane treatment can also be a suitable technology for uranium removal.