TREATMENT OF WASTE LIQUID

摘要

PROBLEM TO BE SOLVED: To efficiently recover a useful material contained in waste liquid with a relatively simple device and a treating process and to make the waste liquid harmless to easily dispose after the useful material is recovered. SOLUTION: The waste liquid containing citric acid and/or phosphoric acid and hydrofluoric acid is treated by a process to neutralize the waste liquid with Ca(OH)2 to form calcium citrate and/or calcium phosphate, a process to filter the waste liquid within a prescribed time after Ca(OH)2 is added in the prestage to recover the solid material of calcium citrate and/or calcium phosphate, and a process to hold the filtrate remaining in the prestage for a prescribed time to generate calcium fluoride.