|This experiment was performed on three parts with prepared coagulants. (1) The characterization of coagulation for PACl coagulants. (2) Comparison of the characterization of coagulation with PAS and PACl coagulants. And (3) Comparison of the characterization of coagulation for the addition of calcium with PACl. Coagulation experiments were conducted with several dosages and pH for each coagulants. For the characterization of coagulation with PACl coagulants, coagulation of Nakdong river waters with three PACls (r=2.0, 2.2, 2.35) showed that the effectiveness of the three coagulants can be considered as r=2.2 > 2.0 > 2.35 which are also the order of higher polymeric aluminum contents. For the comparison of the characterization of coagulation for PAS and PACl coagulants, PAS (r=0.75) coagulants was more effective than other coagulant for the removal of organic matters by sweep floc mechanism with Al(OH)_3(s). For comparison of the characterization of coagulation for the addition of calcium with PACl, the presence of divalent cation like Ca^2+ was supposed to influence the complex formation of organic anions. From the result of test on coagulation at various pH ranges, the PACl was least affected by the coagulation pH, and the addition of calcium to PACl was very effective for the removal of turbidity and organic materials over broader pH range (pH 4-9).