Column study of enhanced Cr(VI) removal by bio-permeable reactive barrier constructed from novel iron-based material and Sporosarcina saromensis W5.

ABSTRACT

In this study, the feasibility of Cr(VI) removal from synthetic groundwater by bio-permeable reactive barrier constructed from novel iron-based material (SiO2/nano-FeC2O4 composite, SNFC) and Sporosarcina saromensis W5 was investigated. According to breakthrough study, an enhanced Cr(VI) removal was found in Bio-SNFC column. The Cr(VI) removal performances of biotic column with 0.2 g biomass and 0.4 g biomass were 16.2 mg/g and 17.9 mg/g, respectively, which were 19.6% and 32.1% higher than that of abiotic column (13.5 mg/g). However, excessive biomass (0.9 g) would cause pore clogging and have a negative impact on the Cr(VI) removal performance of the biotic column, whose removal capability (29.1%) was lower than that of abiotic column. The introduction of proper microorganisms enhanced the utilization of iron and enabled a higher proportion of Fe(II) in biotic column, which provided more reactive sites for Cr(VI) removal. The solid phase characterization indicated the generation of Fe(III) oxide/hydroxide on SNFC surface. The removal of Cr(VI) in Bio-SNFC column was depended on reduction-precipitation, and the final products related to chromium were mainly Cr(OH)3 and Cr2O3. The present work provides a new and sustainable remediation technology for in situ bioremediation of Cr(VI)-contaminated groundwater.