Selection of Optimized Binders for Dechlorination of Trichloroethylene-Contaminated Sites by Jet Grouting and Deep Soil Mixing

Abstract

The remediation of sites contaminated with chlorinated hydrocarbons (CHCs) poses a challenge, especially in built up areas. Nanoscale zero-valent iron (nZVI) can reduce CHCs to nontoxic compounds. Jet grouting and deep soil mixing is used to overcome the difficulty of homogeneous distribution of nZVI in heterogeneous soils. Because these techniques facilitate a synergistic contaminant treatment and installation of construction elements, it is important to know the reactive interactions among involved compounds. In this study six binder materials [bentonite and ordinary portland cement (OPC), among others] have been investigated for interactions with the reductive dechlorination of trichloroethylene (TCE) by nZVI. The installation process was simulated in batch experiments, and the reaction products (CHC, intermediate products, and hydrogen) were observed using headspace gas chromatography. None of the binders inhibited dechlorination of TCE compared to a control experiment, and the two clay materials even catalyzed the reaction by a factor of up to 12.9. Hydrogen evolution was determined as a sensible indicator for the suitability of a particular binder, ranging from 12.8 to 4,400 mmol.