Recent advances in surfactant-enhanced In-Situ Chemical Oxidation for the remediation of non-aqueous phase liquid contaminated soils and aquifers

Protecting soils and groundwater from contaminants is a global challenge and remediating contaminated sites may require decades and many resources. Non-aqueous phase liquids (NAPLs) resulting from oil and gas exploration or drilling, coal gas plants, leaking storage tanks and wood treatment facilities are major contaminants of subsurface soil and groundwater. In-Situ Chemical Oxidation (ISCO) has certain limitations with respect to cost, time, and rebound of contaminants when it is applied to remediation of NAPLs. The development of plant-based biodegradable and environmentally friendly surfactants has opened the door to developing an innovative Surfactant Enhanced In-Situ Chemical Oxidation (S-ISCO) system for remediating hydrocarbon contaminated soils and aquifers. This review highlights the state of the art of this technology and compares it to ISCO. An overview on the three most important components of S-ISCO - surfactant/co-solvent mixtures, the catalyst and/or the oxidant and the free radicals is presented. The major factors affecting the application of S-ISCO for the remediation of contaminated sites are highlighted. This review delivers a detailed explanation on the recent case studies and field applications of S-ISCO and factors affecting its implementation.