Floc growth kinetics in magnesium hydroxide coagulation process

Abstract

The population balance modeling (PBM) had been applied to simulate the floc growth with time in magnesium hydroxide coagulation process. Floc number and size distribution were investigated to evaluate the kinetics in a continuous steady experiment. The floc grows fast in rapid mixer and very slow in flocculation basin and sedimentation tank. The experimental data agreed well with the size-dependent model, and the floc formation and growth empirical function was also obtained to understand the relationship between floc formation rate and growth rate under different stages of coagulation. It was also found that floc growth rate increased with the increase of floc size. Although the floc counts in the range of 2–5 μm accounting for about 90%, the setting characteristics of kaolin colloidal suspensions presents good and the turbidity removal efficiency can reach 98%.

Keywords:

• Magnesium hydroxide
• Coagulation
• Floc growth
• Kinetics
• Model

Acknowledgment

The authors would like to acknowledge the financial support of Tianjin Natural Science Foundation project (10JCYBJC05700).