The Efficacy of Magnetization in Enhancing Flocculation and Sedimentation of Clay Particles

Abstract

【Objective】 Sedimentation and particle clogging is a phenomenon often occurring in irrigation pipe networks. The purpose of this paper is to investigate the feasibility and efficacy of magnetization on enhancing particle flocculation so as to alleviate sedimentation. 【Method】 We used suspension of kaolin clay at concentration of 0.5, 1, 1.5, 3 and 5 g/L as the testing particles, and mixed them with potassium sulfate at concentration of 0.25 g/L, urea at 0.5 g/L and compounded fertilizer at 0.75 g/L. Each solution was magnetized at strength at 0.2 T (W1), 0.4 T (W2) and 0.6 T (W3), respectively, with non-magnetization taken as the control (CK). We then let the suspension to settle in a cylinder, during which we measured the turbidity and median sedimentation velocity at the height of 10 cm, as well as the change in sedimentation composition, zeta potential, pH, conductivity and viscosity of the sample. 【Result】 Compared with CK, magnetization enhanced flocculation of the kaolin particles and increased its sedimentation as a result (p<0.01). When the magnetization intensity was 0.4 T, the flocculation of the particles peaked and it associated sedimentation maximized. Compared with CK, magnetization also increased the median particle size by 14.7%, reduced the proportion of clay particles by 25.0% and the zeta potential by 68.7%. The efficacy of magnetization on the median size of the sediments, proportion of the clay particles and the zeta potential all varied with fertilizer application, with the impact maximizing after potassium sulfate was applied and minimizing when urea was applied. 【Conclusion】 Magnetizing irrigation water can significantly promote flocculation and sedimentation of clay particles; it can be used to alleviate clogging of irrigation pipe network by colloids and fine particles.

Keywords

• magnetization
• flocculation
• sedimentation
• clay particles
• fertilizer