Removal of Chromate from Aqueous Streams by Ultrafiltration and Precipitation

Abstract

The present research seeks to establish an efficient and economic process for removing toxic anions such as chromate, arsenate, and selenate from aqueous streams without requiring addition of large quantities of chemicals. We have established a direct ultrafiltration process which is capable of removing over 99% of chromate ion (CrO42-) from an aqueous feed stream. The ultrafiltration process using a cationic polyelectrolyte is also capable of recovering a large fraction of the input stream and producing it as permeate water of high quality under low operating pressures. The polyelectrolyte is separated from the toxic metal by a precipitation step and can be reused. The process should be particularly useful for treating ground water and wastewater streams contaminated with low concentrations of toxic metal anions.