Screening reactive materials for a permeable barrier to treat TCE-contaminated groundwater: laboratory studies

Abstract

Groundwater contaminated with TCE is of great concern due to its persistence and frequent occurrence in groundwater. Permeable reactive barriers (PRBs) filled with zero-valent iron (ZVI) as the reactive material have been to date effective in reducing TCE concentrations in groundwater to admissible values. Nonetheless, there are several reactive materials other than ZVI that have proven to be effective to treat chlorinated solvents in groundwater. Laboratory batch and column tests were conducted to select effective reactive materials to be placed instead of ZVI in a PRB to treat TCE-contaminated groundwater. Among four materials and four mixtures evaluated, brown coal was found to be the most effective with a removal efficiency of 97 %, followed by compost (86 %) and the mixture, brown coal-compost (86 %). Although the addition of compost to brown coal did not result in higher TCE removal efficiency, it increased the hydraulic conductivity and showed the potential to simultaneously reduce the TCE concentration in groundwater by two processes: sorption and biodegradation. Biodegradation, however, needs to be further investigated to ensure the complete dechlorination of TCE into ethane to avoid the accumulation of daughter products like cis-DCE and vinyl chloride.