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

Abstract

A B S T R A C TSites 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 m 3 of an aqueous surfactant emulsion (13 g L À1 ) was injected at 14.5 m b g.l in the permeable layer (gravel-sand), at a flow rate of 0.6 m 3 h À1 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 À1 ), 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 À1 ) is related to the moderate average contamination of the soil in the test cell (about 1230 mg kg À1 ). 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.

Non-Ionic Surfactant Recovery in Surfactant Enhancement Aquifer Remediation Effluent with Chlorobenzenes by Semivolatile Chlorinated Organic Compounds Volatilization

“…The use of E-Mulse ® in SEAR treatment has been successfully applied in a real soil polluted with DNAPL. This DNAPL is formed by a complex mixture of chlorinated compounds among which are chlorobenze and dichlorobenzene isomers [ 8 ].…”

“…The SEAR technique presents significant benefits compared to other technologies, such as pump and treat [ 8 ], since it increases the efficiency in remediating areas contaminated with NAPLs. However, the SEAR process moves the contamination from the subsurface into the aqueous phase but does not eliminate the contaminant, resulting in a secondary contamination [ 3 ].…”

Soil flushing per la bonifica dei siti contaminati: applicazioni e criticità

“…In caso di contatto accidentale con acque sotterranee, le DNAPL tendono a giungere sul fondo della falda per percolazione, generando così l'inquinamento dell'acquifero 8 . Il sito della discaricaè costituito da uno strato di ghiaia e sabbia con elevata permeabilità ma un gradiente idraulico basso, situato tra uno strato di calce ed uno di marne, entrambi a bassa permeabilità 9 . Per studiare il trasporto dei fluidi iniettati, siè aggiunto un tracciante conservativo, il bromuro, alla soluzione di tensioattivo iniettata.È stata valutata la dispersione del fluido iniettato, l'adsorbimento del tensioattivo, la sua capacità di lavaggio, la concentrazione di contaminanti, di bromuro e di tensioattivo.…”

Treatment of a Complex Emulsion of a Surfactant with Chlorinated Organic Compounds from Lindane Wastes under Alkaline Conditions by Air Stripping

“…This stream can be a mixture of Tween-80 and total petroleum hydrocarbons (TPHs) 9 or tetrachloroethene-nonaqueous 10 and chlorinated organic compounds (COCs) with E-Mulse 3 (E3). 11 The surfactants enhance the removal of pollutants through solubilization and mobilization. The amphoteric properties of the surfactants that reduce interface tension facilitate the transport of hydrophobic pollutants to the aqueous phase.…”