REMEDIATION OF HYDROCARBON-CONTAMINATED AQUIFERS BY MICROWAVE IRRADIATION

Abstract

In this paper, a lab-scale 2.45 GHz microwave (MW) treatment of an artificially hydrocarbon-contaminated aquifer was applied to investigate the effects of different operating powers and times on temperature variation and contaminant removal from both solid and water phases. Results suggest that the applied power significantly influences the final temperature and, consequently, contaminant removal kinetics. A maximum temperature of about 120 °C was reached at 500 W.
A minimal residual diesel concentration of about 100 mg kg-1 or 100 mg L-1 was achieved by applying a power of 500 W for a treatment time of 60 min for the solid or water phase, respectively. Measured residual TPH fractions showed that MW heating resulted in preferential effects of the removal of different TPH molecular weight fractions and that the evaporation-stripping phenomena plays a major role in final contaminant removal processes. The power low kinetic equation shows an excellent fit (r2 > 0.99) with the solid phase residual concentration observed for all the powers investigated. A maximum contaminant removal of 88 or 80% was observed for the MW treatment of the solid or water phase, respectively, highlighting the possibility to successfully and simultaneously remediate both the aquifer phases. Consequently, MW, compared to other biological or chemical-physical treatments, appears to be a better choice for the fast remediation of hydrocarbon-contaminated aquifers.