To use the electrodecantation technique to recover particles from waste cmp slurries.

Electrodecantation, which was shown to concentrate a dilute silica slurry (ILD1200), was applied to the processing of a dilute alumina slurry. Suspensions of alumina particles have been concentrated from 0.5%w/v to 4%w/v using a dc field of 10 V/cm. By reversing the polarity, the concentration ratio was enhanced by a factor of 2, while at the same time eliminating particle deposition on the electrodes. The periodic reversal of the electric field has also proven beneficial in the treatment of dilute silica slurries.