ディスク式磁気分離機による活性汚泥の分離特性  [in Japanese] Characteristics of Activated Sludge Separation Using a Rotating-Disk Magnetic Separator  [in Japanese]

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 permanets magnets. Activated sludge flocs are magnetized by magnetic seeding using ferromagnetic fine particles. This paper describes a method of perdicting the separation characteristics, based on calculation of the particle trajectory. As the flow-out ratio is very sensitive to the particle size, the calcultation 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.