Design of In Situ Fenton Oxidation Based on the Integration of Experimental and Numerical Modelling

Abstract

Criteria for the design of In-Situ Fenton Oxidation (ISFO) is proposed and applied to the development of a pilot-scale treatment of a former refinery site contaminated by hydrocarbons. The proposed criteria takes in account both the regulatory and technical constraints that typically characterize the application of in situ remediation technologies. The proposed design strategy of the ISFO treatment is based on coupling experimental and numerical modelling of the ISFO treatment in an iterative way. Batch tests are performed first, allowing to select the optimal operating conditions and the data on hydrogen peroxide decomposition kinetics. These data, together with the hydro-geological information collected in the field, are then used for the numerical modelling of the ISFO treatment, which allows to define the pilot plant layout and operating conditions and to evaluate the effective delivery of the oxidant and the hydraulic gradient developed in the field. These data are then used to design column scale tests aimed to evaluate the effective hydrogen peroxide longevity, the process performance and the extent of gas production from hydrogen peroxide decomposition.

Fenton’s reaction-based chemical oxidation in suboptimal conditions can lead to mobilization of oil hydrocarbons but also contribute to the total removal of volatile compounds

“…According to Innocenti et al (2014), when increased volatilization was observed at a MTBE-contaminated groundwater site within the same timeframe as the one described here, 99% of the total reductions could still be attributed to chemical mineralization. The H 2 O 2 concentration then used (6%, 1.8 M) was close to the optimal for gas production as described by Baciocchi et al (2010). In the site treatment (Innocenti et al 2014) case, no additional catalysts were used but addition of peroxide was documented to have increased soil acidity from approximately pH 6 to pH 4, a level closer to the optimal pH range than the one described here.…”

In Situ Chemical Oxidation Based on Hydrogen Peroxide: Optimization of Its Application to an Hydrocarbon Polluted Site

“…When this oxidant comes into contact with inorganic compounds, such as iron oxyhydroxide and manganese oxyhydroxide catalysts, or with organic compounds commonly found in surface soils, it can quickly decompose, limiting the utility of ISCO for the remediation of contaminated sites. According to Baciocchi et al [48], these non-productive reactions may well lead to a loss of hydrogen peroxide above 50%.…”