In-well air sparging efficiency in remediating the aquifer of a petroleum refinery site

Air sparging represents an innovative groundwater remediation technology, which has been proved to be capable of restoring aquifers that have been polluted by volatile and (or) biodegradable contaminants, such as petroleum hydrocarbons. This paper presents the design, the installation, and the pulsed operation of an in-well air sparging system at the site of a Greek petroleum refinery. The geographical position, the hydrologeoly, and the contamination features of the chosen study area develop special conditions that, along with the fact that the existing refinery is still active, greatly determine the applicability and the effectiveness of the specific technology. The area that was used for the application of the technology covered almost 600 m² and included five air injection wells and four additional monitoring wells. The pulsed operation of the installed system lasted about 5 months and the results of frequent groundwater sampling and analysis indicate an important decline in total petroleum hydrocarbons (TPH) and benzene–toluene–ethylbenzene–xylene (BTEX) concentrations (up to 99%). However, prior to any attempt to expand the application of air sparging within the facilities of the refinery, special attention should be given to the eccentricities of the site and the ability of the technology to confront more persistent contaminants, such as methyl tertiary-butyl ether (MTBE).