Application of chemical reagents as innovative remediation technologies for groundwater impacted by petroleum hydrocarbons in Italy

Abstract

Innovative technologies with injection of chemical compounds were applied in order to remediate 28 contaminated sites with petroleum hydrocarbon impacted groundwater spread in the Italian territory. The used reagents can be classified into three main technologies: enhanced bioremediation products with oxygen released, In Situ Chemical Oxidation (ISCO) and surfactants. The analysis of these technologies allowed to better understand how to conduct the design, the execution and monitoring phases of the remediation. For the design phase soil and groundwater samples were collected from each site in order to identify the magnitude of the contamination and different calculation methods were tested to quantify the reagents needed for the remediation. For the execution phase the following application methods were performed and analysed: reagents injection into monitoring wells, injection by direct push into the soil, injection into devoted injection wells, application of the reagents into filter socks, application of the reagents into a dig. Pros and cons of each method were so identified. During the monitoring phase the remediation efficacy was evaluated using, not only chemical concentration of contaminants, but also chemicalphysical parameters spatial distribution as a valid support. In the wide range of remediation technologies, the use of chemical reagents has been progressively more appreciated by the designers and by public authorities and is now extensively applied because it is in some cases more effective, cheaper or quicker. These technologies, in fact, proved to be a solid and sustainable alternative to plant technologies, and they were very effective also in fine aquifers. For 62% of the analysed sites, chemical injections led to a reduction of the contamination within 1 year from the application.