Clarification of Book-Mill Effluent by Enzyme-Alum

Effective removal of colloidal and suspended solids from the paper mill effluent can be obtained by the use of an integrated enzyme-alum coagulation system. Starch contained in the mill effluent causes turbidity, which is difficult to remove by the conventional chemical coagulation process. The concept of using starch saccharifying enzyme in conjunction with alum has not been studied extensively. The principal mechanism of enzyme-alum coagulation can be described as a two-step treatment, i.e., enzymatic degradation of effluent starch followed by alum coagulation. The treatment efficiency of the system depends upon the following controlling factors: (1) mill effluent conditions, i.e., pH, and the concentrations of suspended solids and starch; (2) enzyme source, dose, and reaction time; and (3) polymer (alum) concentration used.