| This study is to investigate the coagulation efficiency of kaolin suspension using Alum, PAC, FeCl₃, and cationic polymers and anionic polymers. All the experiments were conducted on the jar tester, and the effect of coagulation dosage was analysed depending on the change of residual turbidity. In order to investigate the properties of coagulation according to mixing conditions, half of optimum dosage, i.e., Alum 10㎎/ℓ, PAC 0.9㎎/ℓ, FeCl₂12㎎/ℓ, cationic polyrner 0.15㎎/ℓ, anionic polymer 0.2㎎/ℓ was added and then the residual turbidity was estimated after certain sedimentation period. According to the results, the coagulation efficiency is better in the case that both organic and inorganic coagulants are used than in the case that inorganic coagulant is only used. Especially, the coagulation efficiency of the condition 2, which polymer was added during slow stirring rate showed the best result. However, the coagulation efficiency of the conditions 1 and 3, which rapid stirring rate was applied after organic coagulant was added. When inorganic coagulant was used together with organic one, approximately 45% of coagulation dosage was reduced, compared to the case of the usage of inorganic coagulant only. Besides, the residual turbidity was also reduced up to 40%. |
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