A combo system consisting of simultaneous persulfate recirculation and alternating current electrical resistance heating for the implementation of heat activated persulfate ISCO

A combo system capable of simultaneous persulfate recirculation and low temperature electrical resistance heating (ERH) was developed for subsurface remediation of organic contaminants using heat-activated persulfate. First, dual-function injection/extraction-electrode wells were designed, and a laboratory-scale combo system was custom-build. Experiments in water tanks and sand tanks were then carried out to investigate the performance of the combo system, and study the impact of main operating parameters (persulfate dosage, recirculation rate, and phase voltage) on volumetric delivery and dispersion of heat and persulfate, and consequent volumetric oxidation of phenanthrene-spiked sand, a model compound of HOCs. The results indicate that the addition of persulfate salts could significantly improve volumetric heating rate, and application of recirculation brought more uniform elevation in temperature and enhanced volumetric degradation of phenanthrene in the recirculation-impacted zone. Overall, this study developed a promising combo system for the implementation of heat-activated persulfate ISCO.