Patent ID: 7988866
Filing Date: 2011-08-02
Classification: C02F

Abstract:
1. A method of treating drainage water, which drainage water contains fumed silica collected by dispersing fumed silica which will become waste into water from the step of handling powdery fumed silica, to reduce the turbidity of said drainage water, comprising the steps of: including an inorganic flocculant composed of a silica sol-aluminum salt and having a molar ratio of silicon to aluminum of 0.05 to 1.5 into fumed silica-containing drainage water having a fumed silica concentration of 0.05 to 3.0 mass % or fumed silica-containing drainage water whose fumed silica concentration has been adjusted to 0.05 to 3.0 mass % to ensure that the concentration of the aluminum becomes 15 to 300 mg/L; and adding an organic polymer flocculant, thereby forming an agglomerated precipitate in the drainage water; and separating said agglomerated precipitate from the drainage water in order to reduce the turbidity of the drainage water.