Strontium is an alkaline-earth element with a chemistry similar to that of calcium and other divalent cations in
Group IIa of the periodic table of the elements. The metal is used in some alloys of tin and lead; various strontium salts are used in pyrotechnics, refining beet sugar, glass, paints, ceramics, and some medicines; and strontium radioisotopes are generated from fission reactions at nuclear installations (McKee and Wolf 1963). The major liquid industrial wastes containing strontium are nuclear wastes including Sr89 and Sr90.
Strontium removals can be achieved through lime-soda ash softening. When stoichiometric chemical dosages are used, a 65-75% removal efficiency of dissolved strontium can be obtained. Increased removals result from chemical dosages greater than stoichiometric amounts.
Phosphate coagulation can also be utilized since strontium cations form relatively insoluble phosphate compounds at high pH. At a pH of 11.3 or greater, with a phosphate to calcium ratio greater than 2.2 to 1, more than 97% of strontium can be removed (Landerdale 1951). Other methods of chemical precipitation include copre-cipitation with aluminum and cesium from acid aluminum wastes, and scavenging by tannic acid or calcium oxalate (Straub 1964).
Inorganic strontium can also be removed from water through cationic ion exchange materials. Processes such as electrodialysis and reverse osmosis also show promise for strontium removal application.
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