In Situ Chemical Reduction of Chlorinated Organic Compounds

Romain Rodrigues (1, 2, 3) , Stéphanie Betelu (1) , Stéfan Colombano (1) , Théodore Tzedakis (2) , Guillaume Masselot (3) , Ioannis Ignatiadis (1)

1 BRGM - Bureau de Recherches Géologiques et Minières (BRGM)
2 LGC - Laboratoire de Génie Chimique
3 ADEME - Agence de l'Environnement et de la Maîtrise de l'Energie

Chlorinated organic compounds (COCs) are common anthropogenic contaminants of soil and groundwater. COCs were industrially produced for different applications, such as dry cleaning, degreasing, or as pesticides. The presence of COCs in the environment is a major concern because of their toxicity and persistence. The most widely used method for their remediation is the conventional pump-and-treat system. However, this technology can hardly achieve a complete remediation because of geological characteristics and the presence of pore space pollution/adsorbed pollution, leading to a residual saturation. Hence, in addition to the improvement of pump-and-treat systems, in situ chemical processes have been largely developed. These chemical processes involve the injection of chemical reagents for the removal of residual source pollution and/or the treatment of plume contamination. Chemical degradation of COCs can be achieved by oxidative or reductive processes. If chemical oxidation has been first developed for in situ application, chemical reduction is one of the most important emerging remediation techniques for COCs treatment. Due to the electronegative character of chlorine substituents, COCs can effectively be transformed via reductive pathways. Moreover, reductive dechlorination has shown higher efficiency on highly chlorinated compounds. This chapter focuses on the presentation of the chemical reduction of the most common COCs pollutants, followed by kinetic and mechanistic approaches related to the use of iron-based particles. Developments on in situ chemical reduction technologies in order to enhance remediation rates are also exposed. Influence of environmental conditions for in situ applications is then developed. Finally, a case study is presented.

Mots clés: Chlorinated organic compounds; chemical reduction; zero-valent iron; kinetics; degradation pathways; solution geochemistry

Domaines: Sciences de l'environnement; Chimie

Romain Rodrigues, Stéphanie Betelu, Stéfan Colombano, Théodore Tzedakis, Guillaume Masselot, et al.. In Situ Chemical Reduction of Chlorinated Organic Compounds. Environmental Soil Remediation and Rehabilitation: Existing and Innovative Solutions, , 2020, ⟨10.1007/978-3-030-40348-5_6⟩. ⟨hal-02540382⟩