METHOD FOR REMOVING SUBSTANCE TO BE REMOVED

摘要

PURPOSE: To solve the problem that waste water generated by mechanical working such as CMP (chemical-mechanical polishing) becomes a colloidal solution because abrasive grains contained in CMP slurry are fine grains and an effective filtration method is not provided so far for the waste water. CONSTITUTION: Waste water containing fine grains as a colloidal solution is filtered by utilizing a second filter 2 comprising a gel membrane formed by suction on the surface of a first filter 1. At this time, suction pressure is made very low and filtering ability is retained while keeping filtration fraction constant and suppressing clogging of the second filter 2. Even fine grains of ≤0.15 μm can be removed.