Removal of Boron from Wastewater by Precipitation of a Sparingly Soluble Salt

摘要

The removal of boron from wastewater has to be considered on a case-by-case basis because no boron compound is known to be precipitated quantitatively. Based on an industrial case, many methods were tested for the treatment of wastewater containing 50 g L~(-1) of sulfuric acid and 0.7 g L~(-1) of boron, and a well-adapted precipitation process consisting of the neutralization of boric and sulfuric acids by powdered calcium hydroxide is proposed. Experimental results show that under optimal conditions (50 g L~(-1) of powdered calcium hydroxide, a temperature of 90℃, and process time of 2 h), the residual boron concentration in solution was reduced from 700 to less than 50 mg L~(-1), a value never reached before by a precipitation process.