| Along with escalating of the rate of waste water being treated, the environment problem of sludge treatment increasingly stands out. The basic purpose of sludge treatment is to reduce the volume. But sludge decrement is dependent on dewatering. Pretreatment must be performed to enhance the rate of sludge dewatering. The mechanism of action, change of sludge characteristic and treatment efficiency are different from different pretreatment methods. The effect on sludge colloid stability and its adsorption ability of magnetic treatment are studied in this paper from a new point of view. The effect of magnetic treatment on forms of sludge granules is also analyzed.The apparatus of magnetic field generating was created. Magnetic field induction, magnetization time, magnetic field direction are considered as parameters. Zeta potential is used as evaluating indicator of sludge colloid stability. Adsorption quantity and specific adsorption quantity are used as evaluating indicator of sludge adsorption capacity to glucose. The change of sludge granule magnetized is recorded by a special system of microscope.The main conclusions as follow:1,Influence of magnetic field induction on zeta potential is relatively large. Its maximum value is at B=0.037T and minimum value is at B=0.045T. Zeta potential vary as a wave along with magnetization time. Its minimum value is at the thirtieth minute. Zeta potential in parallel magnetic field is lower than in perpendicular magnetic field.2,Settling rate is related to magnetic field induction. Its improving extent is obvious at B=0.07T and B=0.09T. Settling rate is also related to magnetization time. Its improving extent is the largest after sludge was exposed in magnetic field for 30 minutes.3,Influence of magnetic field induction on adsorption ability is very large. And its highest value is at B=0.045T. There are some influences for magnetization time on adsorption ability. The ability increase when magnetization time is at the range of 20min～40min. The adsorption balance time of sludge will extend after being magnetized.4,After being magnetized forms of sludge granules will vary. Dewatering capability increases when diameters of sludge granules change larger and sludge granules collect tightly. Forms of sludge granule are related to magnetic field induction. Little granules collect tightly to be large granules when magnetic field induction between 0.037T and 0.07T. When magnetic field induction is larger than 0.07T, granules are almost in independent forms and their diameters are smaller. Forms of sludge granules are also related to magnetization time. Granules collect tightly when magnetization time in 30 minutes. After 30 minutes granules relax. Granules in parallel magnetic field collect better tightly than in perpendicular magnetic field.
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