An experimental apparatus for electroosmotic dewatering which can remove continuously the water in slurry flowing down gravitationally in a passage between two vertical cylindrical electrodes was made for trial. The dewatering body basically consisited of triple vertical long cylinders, and two porous stainless-steel plates were each formed long tapering cylinders and both of the cyliders were used respectively as electrodes and filter media. Hydraulic compressive pressure was naturally applied to the slurry flowing downwards between the electrode cylinders, in order to keep well contact between the slurry and the electrodes. A D.C.electric field or an A.C.electric field with periodical reversals of electrode polarity was applied to the slurry by an electric supplier at the same time. Then the slurry could be dewatered horizontally to both inside and outside of the two cylindrical electrodes. Slurry was prepared by mixing powder particles and deionized water. The slurry was agitated in
a slurry tank to homogenize, and then the slurry was fed to the above-mentioned dewatering body by using a slurry pump. Electric fields such as continuous D.C., D.C.with reversing electrode polarity once, and A.C.with changing frequency and wave form were applied to the slurry flowing downwards in the dewatering body. Using this continuous type electroosmotic dewatering apparatus, experiments were performed by changing applied voltage, slurry material, and slurry feed. The results obtained by the experimental investigations are summarized as follows :
1. For bentonite slurry whichi was hardly dewatered gravitationally, the slurry under D.C.electric field was dewatered alomost only to the outside of cylindrical electrode. On the other hand, the slurry under D.C.elecric field with reversing electrode polarity once was dewatered to both inside and outside of the electrodes, and then the flow rate of drained water was increased compared with the continuous D.C.electric field.
2. In the case of A.C.electric fields, the flow rate of drained water showed a tendency to increase with decreasing the frequency, regardless of wave forms such as sine and rectangular. The drained flow rates to the inside and outside of electrodes were almost the same respectively, and A.C.operation gave an effective electroosmotic dewatering in this apparatus. Less