Development of electrokinetic-flushing technology for the remediation of contaminated soil around nuclear facilities

The effects of a flushing by a pump on an electrokinetic-flushing remediation of contaminated soil were estimated. The soils were sampled from the sites around nuclear facilities which were built on a high hydro-conductivity of sandstone. An electrokinetic-flushing equipment with a pump was manufactured to estimate the effect of a flushing on an electrokinetic-flushing remediation. In order to select an optimal reagent suitable to the characteristics of a soil near nuclear facilities, 4 experiments were executed with 4 candidate reagents selected from 12 reagents and the results of the experiments are as follows. The removal efficiencies of cobalt and cesium from the contaminated soil with the acetic acid were the highest, which were 92.1% and 83.1%, respectively. The effluent solution volume generated from an electrokinetic remediation was very smaller and it was 5% below that from a soil washing. Next, the results from a comparison of an electrokinetic-flushing remediation and an electrokinetic remediation revealed that the removal efficiencies of Co2+ and Cs+ by an electrokinetic-flushing remediation for 5 days were increased by 25% and 35% when compared to those by the electrokinetic remediation, but the effect of a flushing by the electrokinetic-flushing equipment started to decrease after 5 days. The removal efficiencies of Co2+ and Cs+ by an electrokinetic-flushing remediation for 15 days were increased by 6.8% and 7.7% when compared to that by an electrokinetic remediation. Namely, the higher the hydro-conductivity of a soil was, the larger the effect of a flushing was on an electrokinetic-flushing remediation.