Clarification of Polluted Water from Paper Mills with Combination of Cationic Polymers and Alum

Abstract

The main components of polluted water discharged from paper mills are lignosulfonate, kraft lignin, hemicellulose and fiber-fine.
These substances form rather stable colloide and suspension in water due to the negative charges on the surface of substances.
Although it is difficult to clarify the polluted water by sedimenting Pollutants with coagulant, the aluminum sulfate (Alum) has conventionally often been served for this purpose.
The clarification properties of alum are not sufficient.
However, the addition of cationic polymers such as polyethylenimine, protein and chitosan exhibited excellent clarification of polluted water, particularly used with alum.
Thus, the combination of cationic polymers with alum could remove more than 99% of the pollutants such as lignosulfonate, kraft lignin and fiber fines through coagulation and sedimentation.
Also, it was sujested that these coagulated and sedimented pollutants could be used for animal feed and fertilizer.