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Removal of Strontium from Drinking Water by Conventional Treatment and Lime Softening in Bench-Scale Studies
O'Donnell, A., D. Lytle, S. Harmon, K. Vu, H. Chait, AND D. Dionysiou. Removal of Strontium from Drinking Water by Conventional Treatment and Lime Softening in Bench-Scale Studies. WATER RESEARCH. Elsevier Science Ltd, New York, NY, 103:319-333, (2016).
To inform the public.
The United States Environmental Protection Agency Contaminant Candidate List 3 lists strontium as a contaminant for potential regulatory consideration in drinking water. There is very little data available on strontium removal from drinking water. As a result, there is an immediate need to perform treatment studies. The objective of this work is to evaluate the effectiveness of conventional and lime-soda ash softening treatments to remove strontium from surface and ground waters. Conventional drinking water treatment with aluminum and iron coagulants were able to achieve 12% and 5.9% strontium removal at best, while lime softening removed as much as 78% from natural strontium-containing ground water. Systematic fundamental experiments showed that strontium removal during the lime-soda ash softening was related to pH, calcium concentration and dissolved inorganic carbon concentration. Final strontium concentration was also directly associated with initial strontium concentration. Precipitated solids showed well-formed crystals or agglomerates of mixed solids, two polymorphs of calcium carbonate (vaterite and calcite), and strontianite, depending on initial water quality conditions. X-ray diffraction analysis suggested that strontium likely replaced calcium inside the crystal lattice and was likely mainly responsible for removal during lime softening.