A high-molecular flocculant rendered water-soluble by conversion of cyano groups
contained in a high-molecular material, a method for producing the flocculant,
and a method for efficiently processing water using the flocculant. A high-molecular
material containing acrylonitrile as a monomer is processed safely to impart hydrophilicity
to the material and the resulting product is used for water processing to contribute
to environmental conservation. An amino compound is added to a cyano group containing
high-molecular material to convert at least a portion of the cyano group (—CN)
into a molecular structure portion having an imidamino structure and, if necessary,
to convert at, least the portion into one of an acid salt, a quaternary ammonium
salt or a hydrolyzate structure portion to give a high-molecular flocculant. Alternatively,
a high-molecular material having cyano groups is hydrolysed to convert the cyano
group into carbamoyl groups, carboxylic groups or their salts to give a high-molecular
flocculant. This high-molecular flocculant is charged alone or in combination with
commercial flocculants into the water for processing various.