WATER TREATMENT METHOD AND WATER TREATMENT FLOCCULANT

摘要

PROBLEM TO BE SOLVED: To provide a water treatment method which uses a water treatment flocculant comprising a phenol resin-based alkali solution, and with which there is very little secondary pollution due to flocculation residue.SOLUTION: A water treatment method includes adding a flocculant to water to be treated and subjecting the product to membrane separation. The flocculant is formed from an alkali solution of a phenol resin having a melting point between 130°C and 220°C. The water treatment flocculant is obtained by adding an aldehyde to an alkali solution of a novolak phenol resin obtained by reacting a phenol and an aldehyde in the presence of an acid catalyst, and then performing a resol-type secondary reaction in the presence of an alkali catalyst.