DEHYDRATION OF SLUDGE USING BOTH INORGANIC FLOCCULANT AND AMPHOTERIC POLYMERIC FLOCCULANT

摘要

PURPOSE:To increase the treatment amt. of sludge and to obtain a cake with low water content by a method wherein an inorg. flocculant is added to sludge and the pH of the sludge after addition is adjusted to a specific value and an amphoteric polymeric flocculant is added to the sludge to flocculate the same and the sludge is mechanically dehydrated. CONSTITUTION:An inorg. flocculant is added to sludge and the pH of the sludge after addition is adjusted to below 5 and a specific amphoteric polymeric flocculant is added to the sludge to flocculate the same and this sludge is subjected to dehydration treatment. The effective component of this amphoteric polymeric flocculant is composed of an amphoteric copolymer containing a cationic constitutional unit A represented by formula I, a cationic constitutional unit B represented by formula II, an anionic constitutional unit C represented by a specific formula and a nonionic constitutional unit D represented by a specific formula as essential constitutional units and having a compositional mol ratio satisfying the relation of 0.5A-unit/[A-unit + B-unit]1.0 and C-unit/[A-unit + B-unit]0.8 and having intrinsic viscosity of 2.0dl/g (30 deg.C, 1N- NaNO3) or more.