Chromium Removal by Activated Sludge

by Akio Imai, Univ of Texas at Austin, Austin, TX, USA,
Earnest F. Gloyna, Univ of Texas at Austin, Austin, TX, USA,

Document Type: Proceeding Paper

Part of: Environmental Engineering


The behavior of chromium (Cr) in a laboratory-scale, activated sludge process was evaluated. Both pH and the oxidation state of Cr were confirmed as critical parameters for evaluating the fate of Cr. The activated sludge process is capable of removing significant amounts of trivalent Cr left bracket Cr(III) right bracket from solution, but not hexavalent Cr left bracket Cr(VI) right bracket . No oxidation of Cr(III) into Cr(VI) was observed. However, thermodynamic calculations predicted this type of chemical reaction. Cr(VI) exhibited a noticeable inhibitory impact on the MLSS when the units were operated at a pH of 7. A decrease in organic removal coincided with an increase in dissolved Cr(III) and total dissolved Cr.

Subject Headings: Chromium | Activated sludge | Water treatment | pH | Oxidation | Heavy metals | Wastewater treatment

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