Remediation of Cr(VI)-contaminated soil with co-composting of three different biomass solid wastes

This study was focused on co-composting of Cr(VI)-contaminated soil with three different biomass solid wastes for immobilizing Cr(VI). Sequential chemical extraction of the soil was performed to determine Cr fractions changing over time during the compost process. Fluorescence spectroscopy was applied to study the composition and evolution characteristics of organic matter from the municipal sludge and Cr(VI)-contaminated co-composting. The influence of organic matter evolution on the bioavailability of Cr by multivariate statistical analysis was further investigated. Results proved that the Cr(VI)-contaminated soil can be co-composted successfully and this practice results in significant shifts in Cr availability. The concentrations of non-available fractions increased as well as available fractions decreased during the composting stage. The results from the Pearson correlation analysis showed positive relation between non-available fractions and TOC and negative relation between organic matter-bound fraction and TOC. Furthermore, principal factor analysis among Cr and organic matter indicated that the available fractions Cr were bound with humic-like substances and their bioavailability was low. It can be concluded that co-composting provides a method for remediating Cr(VI)-contaminated soil through the decrease of bioavailability of Cr and the binding between available fractions Cr and humic-like substances.