This paper was to study how to apply polyacrylamide (PAA) as a pollution control reagent to bleached Kraft pulp mill effluents. The following problems were discussed : 1) the suitable aluminum sulfate (Alum) dosage, 2) effects of the molecular weight of PAA, 3) effects of the PAA dosage, 4) effects of pH on coagulation.The results are as follows. Removal of COD does not depend on the dosage of PAA, but that of alum. The role of PAA is to make a large and strong coagulation and to result fast sedimentation of it. To form good coagulations, 5 million or more of mol. wt, of PAA is required. The more the dosage of PAA, the faster the rate of sedimentation. Nonionic PAA gives the maximum rate of sedimentation at pH 5-7. Anionic PAA, independently of its degree of hydrolysis (DH), shows the maximum rate of sedimentation at pH 8.