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

Han, Seung woo; Kang, Lim seok; Han, Seung woo; Kang, Lim seok

doi:2015.37.6.325

The Korean text of this paper can be translated into multiple languages on the website of http://jksee.or.kr through Google Translator.

J Korean Soc Environ Eng > Volume 37(6); 2015 > Article

Original Paper

J Korean Soc Environ Eng 2015;37(6): 325-331. doi: https://doi.org/10.4491/KSEE.2015.37.6.325

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

한승우², 강임석¹

¹(주)이에프티 기업부설연구소
²부경대학교 환경공학과

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

Seung woo Han², Lim seok Kang¹

¹EFT R&D Center
²Department of Environmental Engineering, Pukyong National University

Corresponding author

Lim seok Kang ,Tel: 051-629-6527, Fax: 051-629-6523, Email: kangls@pknu.ac.kr

Received: April 22, 2015; Revised: June 9, 2015; Accepted: June 18, 2015. Published online: June 30, 2015.

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 FeCl₃ 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 FeCl₃ > PACl (r=2.2) > PACl (r=1.2) > alum. FeCl₃ 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 FeCl₃ were considered as more appropriate coagulants for the removal of turbidity in the case of raw water exhibiting higher pH.

Key Words: Coagulant, Basicity, Aluminum Salt, Ferric Salt, Coagulation Effectiveness