title: Improving the sweeping efficiency of permanganate into low permeable zones to treat TCE: experimental results and model development.
abstract: The residual buildup and treatment of dissolved contaminants in low permeable zones (LPZs) is a particularly challenging issue for injection-based remedial treatments. Our objective was to improve the sweeping efficiency of permanganate into LPZs to treat dissolved-phase TCE. This was accomplished by conducting transport experiments that quantified the ability of xanthan-MnO4(-) solutions to penetrate and cover (i.e., sweep) an LPZ that was surrounded by transmissive sands. By incorporating the non-Newtonian fluid xanthan with MnO4(-), penetration of MnO4(-) into the LPZ improved dramatically and sweeping efficiency reached 100% in fewer pore volumes. To quantify how xanthan improved TCE removal, we spiked the LPZ and surrounding sands with (14)C-lableled TCE and used a multistep flooding procedure that quantified the mass of (14)C-TCE oxidized and bypassed during treatment. Results showed that TCE mass removal was 1.4 times greater in experiments where xanthan was employed. Combining xanthan with MnO4(-) also reduced the mass of TCE in the LPZ that was potentially available for rebound. By coupling a multiple species reactive transport model with the Brinkman equation for non-Newtonian flow, the simulated amount of (14)C-TCE oxidized during transport matched experimental results. These observations support the use of xanthan as a means of enhancing MnO4(-) delivery into LPZs for the treatment of dissolved-phase TCE.
authors.affiliation: Department of Civil Engineering, University of Nebraska-Lincoln , Lincoln, Nebraska 68588-0531, United States.
authors.forename: Chanat
authors.initials: C
authors.lastname: Chokejaroenrat
authors.forename: Negin
authors.initials: N
authors.lastname: Kananizadeh
authors.forename: Chainarong
authors.initials: C
authors.lastname: Sakulthaew
authors.forename: Steve
authors.initials: S
authors.lastname: Comfort
authors.forename: Yusong
authors.initials: Y
authors.lastname: Li
mesh_terms: D002250:Carbon Radioisotopes; D003198:Computer Simulation; D017895:Manganese Compounds / Q000737:chemistry*; D008962:Models, Theoretical; D010087:Oxides / Q000737:chemistry*; D010539:Permeability; D011135:Polysaccharides, Bacterial / Q000737:chemistry; D012996:Solutions; D013997:Time Factors; D014241:Trichloroethylene / Q000737:chemistry*; D014783:Viscosity
chemical_list: D002250:Carbon Radioisotopes; D017895:Manganese Compounds; D010087:Oxides; D011135:Polysaccharides, Bacterial; D012996:Solutions; C048856:permanganic acid; D014241:Trichloroethylene; C002563:xanthan gum