Remediation of the Alluvial Aquifer of the Sardas Landfill (Sabiñánigo, Huesca) by Surfactant Application

Abstract

Sardas Landfill at Sabiñánigo Huesca is polluted with Dense Non-Aqueous Liquid Phases (DNAPLs) composed of a complex mixture of chlorinated organic compounds (COCs). This DNAPL was produced as liquid waste from lindane production being dumped decades ago in the unlined landfills close to the lindane factory. This DNAPL migrated by gravity through the subsurface and accumulated in the contact between the alluvial and marls layers (about 15 m b.g.l.). Seven injections of an aqueous emulsion of a biodegradable non-ionic surfactant (E-Mulse 3 ®) were carried out at the most polluted areas of the Sardas alluvial. Injections were carried out between April and November 2021 using different surfactant concentrations (6.7, 20, 25 and 50 g/L), injection volumes (0.2 to 7 m3) and injection flow rates (0.08–0.85 m3/h). Injected fluids were extracted in the same well or surrounding wells, and the time elapsed between surfactant injection and extraction varied between 24 and 72 h. A total of 22 m3 were injected into the alluvial, and more than double this injected volume was extracted. Injection and extraction points were in the contact between the marls and the alluvial layer. Extracted fluid accumulated in tanks, and phases separated. DNAPL recovered here was mobilized rather than solubilized and managed as toxic waste. The aqueous supernatant was treated in a wastewater treatment plant with physicochemical treatment (including adsorption in activated carbon) before being discharged into the environment. The transport of the injected fluids was monitored by conductivity profiles using bromide (260–538 mg·L−1) as a conservative tracer. High radial dispersion of the injected fluid was found. Surfactant losses by adsorption in the alluvial and absorption in DNAPL were noticed, and both surfactant and contamination did not escape from the capture zone. Monitoring since 2018 of the COCS in groundwater and the DNAPL presence in the contact between alluvial and marls layers showed a significant reduction of COCs in the treated zone with the surfactant injections.

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

“…Therefore, volatilization can be employed not only to remove COCs from emulsions but also to break them and thus facilitate their further disposal. The reduction of surfactant and pollutant contents in the processed stream permits the treatment of the water stream obtained after the air stripping step under alkali conditions, avoiding other expensive technologies such as incineration in special facilities …”

“…The reduction of surfactant and pollutant contents in the processed stream permits the treatment of the water stream obtained after the air stripping step under alkali conditions, avoiding other expensive technologies such as incineration in special facilities. 41…”

Carbon and Sulfur Isotope Methods for Tracing Groundwater Contamination: A Review of Sustainable Utilization in Reclaimed Municipal Landfill Areas

“…These are then compared with the hydrogeochemical background range, the quality standards for groundwater, or assessments of human health risk [13,14,[43][44][45][46][47][48][49][50]. Evidence of contamination is the presence of BTEX, PAHs, pesticides, micro-and nanoplastics, xenobiotic organic compounds, pharmaceutical compounds, specific substances (per-/polyfluoroalkyl substances), and other components that do not form in the natural environment [19,47,[51][52][53][54][55]. An assessment of water aggressiveness based on the estimation of saturation indices is also a useful method for identifying the groundwater contamination around landfills [56].…”

Three-Dimensional High-Precision Numerical Simulations of Free-Product DNAPL Extraction in Potential Emergency Scenarios: A Test Study in a PCE-Contaminated Alluvial Aquifer (Parma, Northern Italy)

“…The behavior and fate of chlorinated organic compounds in the subsurface have been studied since the early 1980s (e.g., [6][7][8][9][10][11]). Some numerical models, including migration [12] in fractured aquifers [13,14] and remediation of alluvial aquifers [15], using the MT3DMS numerical code [16,17], have been written to simulate their migration in aquifer systems.…”