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Comparison of Al(III) and Fe(III) Coagulants for Improving Coagulation Effectiveness in Water Treatment

정수처리 응집효율 개선을 위한 Al(III)염과 Fe(III)염 응집제의 비교

  • 한승우 ((주)이에프티 기업부설연구소) ;
  • 강임석 (부경대학교 환경공학과)
  • Received : 2015.04.22
  • Accepted : 2015.06.18
  • Published : 2015.06.30

Abstract

The experimental results of the characteristics of aluminum based and ferric based coagulants for the Nakdong River water showed that the main hydrolysis species contained in alum and $FeCl_3$ are monomeric species of 98% and 93.3%, respectively. The PACl of r=1.2 produced by the addition of base contained 31.2% of polymeric Al species and the PACl of r=2.2 contained 85.0% of polymeric Al species, as showing more polymeric Al species with increasing r value. Coagulation tests using Al(III) and Fe(III) salts coagulants for the Nakdong River water showed that the coagulation effectiveness of turbidity and organic matter was high in the order of $FeCl_3$ > PACl (r=2.2) > PACl (r=1.2) > alum. $FeCl_3$ has showed better flocculation efficiency than Al(III) salts coagulants. In addition, in case of Al(III) coagulants, the Al(III) coagulants of higher basicity, which contained more polymeric Al species, resulted in better coagulation efficiency for both turbidity and organic matter removed. The optimum pH range for all of the coagulants investigated was around pH 7.0 under the experimental pH range of 4.0~9.5. Especially, the highest basicity PACl (r=2.2) and $FeCl_3$ were considered as more appropriate coagulants for the removal of turbidity in the case of raw water exhibiting higher pH.

Keywords

Coagulant;Basicity;Aluminum Salt;Ferric Salt;Coagulation Effectiveness

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