| 摘要 |
PROBLEM TO BE SOLVED: To efficiently recover water and/or a polishing agent by flocculating particles contained in a CMP(chemical-mechanical polishing) waste soln. by a small amt. of a chemical agent and separating the flocculated treated soln. by a UF membrane to perform membrane separation without clogging the UF membrane. SOLUTION: A CMP waste soln. 6 is introduced into a flocculation treatment tank 1 and a surfactant 7 is injected into the tank 1 and a pH control agent 8 is also injected thereinto to adjust the waste soln. to pH 6.8 or less to flocculate abrasive grains and the flocculated treated soln. is supplied to a UF membrane separator 2 to perform membrane separation. A conc. soln. 15 is recovered as a polishing agent and a permeated soln. 12 is subjected to membrane separation by an RO membrane separator 3 and a permeated soln. 14 is recovered as treated water.
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