New insight into the mechanism of remediation of chromium containing soil by synergetic disposal of ferrous sulfate and digestate.

In this work, an innovative technology by using ferrous sulfate combined with digestate, was applied to the Cr (VI) reduction. In the combined process, 3% ferrous sulfate, 5% digestate, 2% glucose, 30 °C and 50% moisture content were proved to be the optimal operating conditions. The combined process achieved 100% reduction of 3000 mg/Kg Cr (VI) within 10 days. Ferrous sulfate and digestate had a synergistic effect on Cr (VI) reduction. XPS analysis showed that Cr (VI) was reduced to Cr (III) in the combined treatment group. Functional microorganisms in digestate played an important role in the reduction of Cr (VI). Sulfate and Fe(III) could be reduced by microorganisms in digestate, and the reduction products accelerated the reduction of Cr (VI). The combined treatment improved the relative abundance of Clostridium, Acinetobacter, and Tissierella, which were of great significance for the reduction of Cr (VI).