FIXING AND REMOVING METHOD OF FLUORINE AND PHOSPHORUS IN WASTE WATER CONTAINING FLUOROPHOSPHORIC ACID COMPOUND

PROBLEM TO BE SOLVED: To reduce the fluorine concn. and the phosphorus concn. in waste water till low level by decomposing fluorophosphoric acid to hydrogen fluoride and phosphoric acid and fixing and removing fluorine and phosphorus. SOLUTION: Hydrochloric acid is added to the waste water containing a fluorophosphoric acid compd. so that its concn. in the waste water may be 2-10 wt.%, then the waste water to which the hydrochloric acid is added is heated to 80 deg.C to its boiling point to decompose the fluorophosphoric acid compd. to the hydrogen fluoride and the phosphoric acid and also gaseous hydrogen chloride at the treating tank for housing the waste water is introduced to a condenser provided at the outside of the treating tank, then a calcium salt is added to the waste water after decomposition to fix and remove the fluorine and the phosphorus.