High carbon iron filings (HCIF) and metal reducing bacteria (Serratia sp.) co-assisted Cr (VI) reduction: Kinetics, mechanism and longevity

Abstract

Permeable reactive barriers (PRBs) have been an area of interest for in-situ remediation of groundwater. However, the corrosion of iron used in PRBs has been an area of concern. This study was aimed to enhance the long term performance for reduction of Cr (VI) by high carbon iron filings (HCIF) co-assisted with Serratia sp. Cr (VI) reduction by HCIF alone followed pseudo-first order kinetics and the reaction rate was 0.382 h−1 for 50 mg/L of Cr (VI) which declined to 0.0017 mg−1 L h−1 in combined system. But in cyclic studies, the reduction of Cr (VI) with HCIF alone system declined to 70% after 2 cycles whereas more than 90% reduction was observed in combined system up to four cycles. The corrosion potential and XRD data supported that Serratia sp. have positive effect on longevity of HCIF for Cr (VI) reduction.