Combination of nZVI and DC for the in-situ remediation of chlorinated ethenes: An environmental and economic case study
PERGAMON-ELSEVIER SCIENCE LTD, THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND
Over the past two decades, the use of nanoscale zero-valent iron (nZVI) has emerged as a standard method of contaminated groundwater remediation. The effectiveness of this method depends on key intrinsic hydrogeological parameters, which can affect both reactivity of the nanoparticles and their migration in the aquifer. In the case of low hydraulic permeability, the migration of nanoparticles is limited, which negatively influences remediation. An application of nZVI reinforced with a DC electric field led to a significant increase in the efficiency of remediation, as demonstrated by long-term monitoring at a former industrial site in Horice (Czech Republic). For the method testing, a 12 x 9 m polygon was defined around well 154, where the original contamination was predominantly composed of DCE (7300 mu g/l), and with a total concentration of chlorinated ethenes of 8880 mu g/l. During the first stage of the activities, 49 kg of nZVI was injected and monitored for two years. Subsequently, the electrodes were installed, and for three years, the synergistic action of nZVI within an applied DC field was monitored. Based on 32 monitoring campaigns performed over the six years, the combined method was compared with an application of the only nZVI in technical, environmental and economic terms. Technically, the method requires annual reinstallation of anodes as a result of their oxidative disintegration. Environmentally, the method provides significantly improved chlorinated ethane reduction, remediation of low permeable zones, and extended efficiency. Economically, the method is five times cheaper when compared to the nZVI used alone.
nZVI, Nanoremediation, Electrokinetics, Chlorinated hydrocarbons, Reductive remediation methods, Economic evaluation