Bouzid I, Fatin-Rouge N. Assessment of shear-thinning fluids and strategies for enhanced in situ removal of heavy chlorinated compounds-DNAPLs in an anisotropic aquifer.
JOURNAL OF HAZARDOUS MATERIALS 2022;
432:128703. [PMID:
35316641 DOI:
10.1016/j.jhazmat.2022.128703]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 02/17/2022] [Accepted: 03/11/2022] [Indexed: 06/14/2023]
Abstract
The removal of chlorinated organic hydrocarbons (COHs) -DNAPLs was studied in permeability-contrasted sandboxes with an egg-box shaped substratum. Aqueous solutions were compared to viscous shear-thinning fluids (xanthan solution and foam). Interfacial and viscous effects were compared by increasing the capillary number of injected fluids. Non-spatially targeted DNAPL recovery (NSTR) where the driving force was the injection pressure, was compared to spatially targeted DNAPL recovery (STR) where a pumping system allowed the controlled flow. A historical contamination made of a complex mixture of COHs and hexachlorobutadiene (HCBD) as a model were used. NSTR results showed that DNAPL recovery with non-viscous liquids did not exceed 40%. The best results were obtained for xanthan solutions with surfactant ~ 1.3 ×CMC for which pure phase recovery amounted to 88% and 93% for HCBD and for the historical DNAPL, respectively. The STR strategy showed similar recovery yields, whereas xanthan concentrations were 10-times lower. Mass balances on DNAPL showed that at most, 0.15% of COHs was dissolved in the aqueous effluents. NZVI (1 g.l-1) were delivered in xanthan in view of the chemical degradation of residual COHs and showed a 65% transmission through the low permeability soil.
Collapse