Flocculation Kinetics Using Fe(III) Coagulant in Advanced Water Treatment: The Effect of Sulfate Ion

상수처리시 Fe(III) 응집제를 이용한 응집동력학에 관한 연구 : 황산이온의 영향

  • 강임석 (부산수산대학교 환경공학과) ;
  • 이병헌 (부산수산대학교 환경공학과)
  • Published : 1995.10.01


The study of flocculation kinetics is of fundamental interest in the field of water treatment, because rational study of the factors affecting the coagulation process should be based on the rate of particle growth. The effect of sulfate on flocculation kinetics were examined using ferric nitrate as a coagulant to coagulate kaolin clay in water under several experimental conditions. Both the particle size distribution data obtained from the AIA and the on-line measurement of turbidity fluctuation by the PDA were used to measure flocculation kinetics. Results show that sulfate ion added to the kaolin suspension played an important role in the flocculation process, not only improving flocculation kinetics at more acidic pH levels but also changing surface charge of particles. The kinetics of flocculation were improved mainly by the enhanced rate and extent of Fe(III) precipitation attributed to the addition of sulfate, and thereby, better interparticle collision frequency, but little by the charge reductions resulting from the sulfate addition. The increase in sulfate concentration beyond $3\times10^{-4}M (up to 2\times10^{-3}M)$ did not induce further improvement in flocculation kinetics, although the higher concentrations of sulfate ion substantially increased the negative ZP value of particles. Key Words : Flocculation Kinetics, Fe(III) Coagulant, Sulfate ion, Turbidity Fluctuation.


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