Direct Cr (VI) bio-reduction with organics as electron donor by anaerobic sludge

Publisher:
Elsevier
Publication Type:
Journal Article
Citation:
Chemical Engineering Journal, 2017, 309, pp. 330-338
Issue Date:
2017-02-01
Filename Description Size
1-s2.0-S1385894716314875-main.pdf1.41 MB
Adobe PDF
Full metadata record
Industrial activities produce lots of Cr (VI)-containing wastewater. This study presented a detailed work on direct Cr (VI) bio-reduction (i.e. Cr (VI) is reduced with organics as electron donor directly) by anaerobic sludge through both batch and long-term experiments. Effects of pH and initial Cr (VI) concentrations on direct Cr (VI) bio-reduction activity were evaluated. The highest direct Cr (VI) bio-reduction rate was achieved at pH 8.0 at 104 mg Cr (VI)/g MLVSS/d (MLVSS: mixed liquor volatile suspended solids), corresponding to the highest protein release (124 mg/g MLVSS) and cell viability (71%). In contrast, the direct Cr (VI) bio-reduction rates were 46, 70 and 82 mg Cr (VI)/g MLVSS/d, respectively, at pH 6.0, 7.0 and 9.0. Also, the direct Cr (VI) bio-reduction activity decreased by 74% when initial Cr (VI) concentration increased from 10 mg/L to 50 mg/L. The contribution of chemical adsorption to Cr (VI) removal was found to be negligible, whereas biosorption played a role in Cr (VI) removal although its role was insignificant. Indirect Cr (VI) bio-reduction (i.e. Cr (VI) is chemically reduced by sulfide produced from biological sulfate reduction) rate (990 mg Cr (VI)/g MLVSS/d) was faster than that (210 mg Cr (VI)/g MLVSS/d) of direct Cr (VI) bio-reduction, indicating that indirect Cr (VI) bio-reduction would dominate the Cr (VI) bio-reduction pathway if both Cr (VI) and sulfate were present. The direct Cr (VI) bio-reduction was then successfully demonstrated in an up-flow anaerobic sludge bed (UASB) reactor, where the Cr (VI) was completely removed with a Cr (VI) removal rate of 1.0 mg Cr (VI)/L/h. 454 pyrosequencing results revealed that direct Cr (VI) bio-reduction related genera were Desulfovibrio, Ochrobactrum and Anaerovorax.
Please use this identifier to cite or link to this item: