| abstract |
[PROBLEMS] To provide a method for dewatering sludge which is excellent in coagulation dewatering performance, requires a small amount of addition, and can give a cake having a low water content. SOLUTION: An inorganic flocculant is added to sludge, and the pH is adjusted to 4 to 8. And then adding the following amphoteric polymer flocculant to dewater the sludge. Amphoteric polymer coagulant: Dialkylaminoethyl methacrylate quaternary salt (1), dialkylaminoethyl acrylate quaternary salt (2), (meth) acrylic acid or its salt (3) and (meth) acrylamide (4) An amphoteric polymer flocculant comprising a copolymer having a monomer unit and a composition molar ratio of (3) / [(1) + (2)] <0.8. |