Electro-Osmotic Dewatering under Intermittent Power Application by Rectification of A.C. Electric Field.

Abstract

A continuous DC electric field has been generally used for fundamental study and practical application of electro-osmotic dewatering. Under DC conditions, however, the electrical contact resistance between the electrode and the dewatered material is excessively increased in the dewatering process, resulting in interruption of the dewatering process. For efficient performance of electroosmotic dewatering, intermittent power application was used to reduce such excessive increase of the electrical contact resistance with the lapse of time. An intermittent electric field was made by rectifying an AC electric field, and it was constituted of half waves. Both rectangular and sine waves were used as the wave form of an AC electric field. Electro-osmotic dewatering under the rectified half-wave intermittent electric field was investigated experimentally, under both conditions of the same peak-value voltage and the same effective-value (r.m.s.-value) voltage as the voltage applied under DC and AC electric fields.Intermittent power application is suggested to reduce the increase of the electrical contact resistance with time caused by the DC process. In the case of intermittent power application having the same effective voltage as DC and AC, the rate and the amount of removed water were increased compared with DC and AC fields, and the efficiency of electric power consumption for the amount of removed water was much higher than them.