1999 年 23 巻 4_2 号 p. 1553-1556
In waste water treatment processes, a large pool for sedimentation is used for solid-liquid separation after biological treatment. As a substitute for this pool, we are developing a magnetic separator that has a rotating disk with Nd-Fe-B permanent magnets. Activated sludge flocs are magnetized by magnetic seeding using ferromagnetic fine particles. This paper describes a method of predicting the separation characteristics, based on calculation of the particle trajectory. As the flow-out ratio is very sensitive to the particle size, the calculation takes account of the particle diameter distribution. However the calculated results for the flow-out ratio are much higher than the experimental results. The reason is that the calculation is based on the particle diameter measurement which is not suitable for evaluating the condition of particle cohesion. Our next task is to develop a method of measuring particle diameters like that used in the magnetic separator.