Organic permeable barriers for Cr(VI) removal from contaminated groundwater – lab-scale experiences

This paper presents the results of a lab scale experience for the use of low cost materials (green compost mixed with pea gravel) in the implementation of an organic-based permeable barrier as an in situ remediation technology for groundwater. The system relies on the adsorption capacity of the organic-based matrix and on the anaerobic microbial metabolism of the bacteria residing in green compost, since the reducing environment established contributes to the reduction of Cr(VI) into Cr(III). The removal efficiency of the selected reactive medium was evaluated through both batch and column tests. The removal was the result of the combination of abiotic as well as biological processes: the former in the first period of the batch tests and the latter after about 48 hours, corresponding to the time needed by the biomass to acclimate the anaerobic environment. The gravel is used as the structure matrix, since its contribution to the removal is quite negligible.