Migration and remediation of organic liquid pollutants in porous soils and sedimentary rocks: a review

摘要

Underground pollution of soils and sediments is a major yet overlooked health issue, because pollutants are often trapped into inaccessible and complex porous media, and may re-enter ecosystems days to hundred of years later. In particular, removing the organic liquid pollutants completely from porous media is almost impossible, especially in low-permeability zones. Here, we review the migration and remediation techniques of organic liquid pollutants in the subsurface, with focus on low-permeability zones. We discussed migration mechanisms in the vadose and saturation zones. Remediation techniques include electrokinetic remediation, bioremediation, and the use of polymers and foam. Electrokinetic remediation is well suited for ultralow-permeability areas such as silts and clays. Microbial remediation is environmentally friendly with minimal disturbance in soil systems, yet underground conditions may limit bacterial growth. Polymers reduce pollutant mobility and improve the stability of the displacement front. Nanoparticles modify the viscosity of polymer solution, improve the sweep efficiency and reduce interfacial tension reduction. Foams may solve the problems caused by bypass and preferential flows of surfactants in the high-permeability region.