Clarifying filtration of fine particle suspensions aided by electrical andacoustic fields

An experimental rig has been developed to study the effects of electric and acoustic fields on constant pressure filtration. The filter is designed wi th the medium support acting as a cathode, and with a variable height anode located in the feed suspension inducing an electric field normal to the fi lter medium. A flat plate ultrasonic transducer attached to the side of the filter applied ultrasonic energy tangentially to the medium. Electric and acoustic fields, suspension characteristics and process parameters can all be varied independently. Experimental results demonstrate that acoustic fields have little or no eff ect on the dewatering of suspensions of concentrations higher than 1% by vo lume. Changes in the conductivity induced by ultrasonic irradiation are pH dependent and may affect the suspension such that application of an electri cal field is enhanced. Electric fields enhance filtration rates but form fi lter cakes with higher porosities. The power consumed by the ultrasonic fie ld is large; the power consumed by the electric field is much smaller and i s more effective at improving filtration characteristics.