Precipitative removal of As, Ba, B, Cr, Sr, and V using sodium carbonate

Sodium carbonate softening at pH 10.3 is a viable method of removing the inorganic contaminants arsenic, barium, chromium, strontium, and vanadium from drinking water sources. A broad survey revealed that removals varied widely and were dependent on solution composition. Median removals of As, Ba, Cr, Sr, and V were 24, 100, 92, 99, and 60%, respectively. Linear and nonlinear empirical models were fit for crudely estimating the removal of these contaminants in the presence of other elements that are typically removed in the softening process (i.e., calcium, magnesium, silicon, iron, and aluminum). Boron was removed to a much lesser extent (median removal 2%), indicating soda ash softening is not a promising treatment option for this purpose.