Soil flushing pilot test in a landfill polluted with liquid organic wastes from lindane production

Aurora Santos; Carmen M Domínguez; David Lorenzo; Raul García-Cervilla; Miguel A Lominchar; Jesús Fernández; Jorge Gómez; Joaquín Guadaño

doi:10.1016/j.heliyon.2019.e02875

Soil flushing pilot test in a landfill polluted with liquid organic wastes from lindane production

Heliyon. 2019 Nov 19;5(11):e02875. doi: 10.1016/j.heliyon.2019.e02875. eCollection 2019 Nov.

Authors

Aurora Santos¹, Carmen M Domínguez¹, David Lorenzo¹, Raul García-Cervilla¹, Miguel A Lominchar¹, Jesús Fernández², Jorge Gómez³, Joaquín Guadaño³

Affiliations

¹ Chemical Engineering and Materials Department, Complutense University of Madrid, Spain.
² Department of Rural Development and Sustainability, Government of Aragon, Spain.
³ EMGRISA, Empresa Para La Gestión de Residuos Industriales, S.A., S.M.P,. M.P., Madrid, Spain.

Abstract

Sites contaminated by Dense Non-Aqueous Liquid Phases (DNAPLs) containing chlorinated compounds are a ubiquitous problem caused by spills or the dumping of wastes with no concern for the environment. Their migration by gravity through the subsurface and their accumulation far below ground level make in-situ treatments the most appropriate remediation technologies. In this work, an aqueous solution containing a non-ionic and biodegradable surfactant was injected in the Sardas alluvial layer contaminated at some points with DNAPL (formed by a mixture of more than 28 chlorinated compounds) from lindane production. A volume of 5.28 m³ of an aqueous surfactant emulsion (13 g L^-1) was injected at 14.5 m b g.l in the permeable layer (gravel-sand), at a flow rate of 0.6 m³ h^-1 and the groundwater was monitored within a test cell (3.5 m radius) built ad hoc. The flow of the injected fluids in the subsurface was also evaluated using a conservative tracer, bromide (130 mg L^-1), added to the surfactant solution. Concentration of contaminants, chloride, bromide and surfactant, surface tension and conductivity were measured at the injection point and at three monitoring points over time. High radial dispersion was noticed resulting in high dilution of the injected fluids. The surfactant was not adsorbed in the soil during the injection time, the adsorption of the surfactant took place in the meantime (15 h) between its injection and the groundwater (GW) extraction. The concentration of chlorinated compounds dissolved from the soil in the surfactant aqueous phase when equilibrium was reached (about 850 mg L^-1) is related to the moderate average contamination of the soil in the test cell (about 1230 mg kg^-1). In contrast, the extraction of the free DNAPL in the altered marls layer was highly enhanced due to the addition of the surfactant. Finally, it was found that the surfactant and the contamination did not migrate from the capture zone.

Keywords: Alluvium; Chemical engineering; Contaminant transport; DNAPL; Environmental chemical engineering; Environmental pollution; Landfill; Lindane wastes; Soil pollution; Surfactant; Tracer.