PURE OXYGEN BARRIER WITH GROUND BIO2® SYSTEM FOR GROUNDWATER REMEDIATION AT A PHARMACEUTICAL SITE IN THE NORTH OF ITALY

Abstract

A groundwater plume containment measure, consisting of a double barrier of Pure Oxygen microinjections in groundwater (GROUND BIO2®), was installed and started at the end of 2014 in a pharmaceutical production site in Northern Italy, characterized by high concentrations of organic contaminants (approximately 90.000 µg/l of Total Hydrocarbons and 60.000 µg/l of Aromatic Hydrocarbons). The first year of in-situ operation showed that the technology allowed the activation of the indigenous biomass and the promotion of the aerobic biodegradation of the organic pollutants present in groundwater with yields close to 100%. The Pure Oxygen double-barrier consists in 33 injection points, with a total extension of about 140 meters, distributed at the site to determine a partial overlapping of the treatment zones in the most contaminated area. The up-gradient barrier reduces the mass of contaminants under the central sector of the site, while the down-gradient barrier ensures the finishing of the contaminant concentrations immediately up-gradient the site boundary. After four months of treatment, high removal rates have been reached at the injection wells: 100% for BTEX and 95%-100% for Total Hydrocarbons. After six months, high removal rates have been reached also at the monitoring wells between the two barriers (99%) and, at the Points of Compliance (POCs), the concentrations generally decreased below the regulatory limits. The chemical data have been confirmed by the microbiological analyses, indicating an increase of 1-2 orders of magnitude of the total counts and the specific microbial counts. The case study demonstrates the applicability of this technology for the treatment of the organic contamination of groundwater, with more limited environmental impact and financial effort compared with the other available technologies (pump and treat, air-sparging, bio-sparging, slow oxygen release compounds, etc.).