Multi-Scale Experiments to Evaluate Mobility Control Methods for Enhancing the Sweep Efficiency of Injected Subsurface Remediation Amendments
2010
McCray, John E. | Munakata-Marr, Junko | Silva, Jeffrey A. | Davenport, Sean | Smith, Megan M.
This research investigates enhanced delivery of remediation agents to hydraulically inaccessible zones using water-soluble polymers, with a focus on chemical oxidation and bioremediation of chlorinated solvents. Our investigations revealed that the xanthan polymer may be compatible with both permanganate and persulfate oxidants, but the xanthanpermanganate pair is most promising for future use. Both polymers are compatible with bioaugmentation remediation, but neither polymer was demonstrated to be an effective electron donor to achieve complete dechlorination. The confirmation of the presence of simple reducing sugar compounds resulting from xanthan biodegradation leads us to infer that the use of xanthan polymers in the subsurface should not results in long-term deleterious effects on groundwater quality. Polymer injections will result in some clogging near the injection zone, but this is not expected to significantly influence field application. Batch and column tests were helpful in constructing numerical models in up-scaled systems (2-D tanks). The UTCHEM model was able to successfully simulate 2-D experimental data for layered heterogeneous systems. Experimental data from intermediate-scale 2-D systems, and from hundreds of numerical simulations, suggest that polymer floods are very effective at improving sweep efficiency in layered systems, and that performance is improved in systems with more layers. Additional 2-D experiments confirmed that a polymer-oxidant flood enhanced mass removal and reduced postremediation mass flux, whereas the effectiveness of treatment depends on the delivery method. Overall, polymer flooding shows considerable promise for improving delivery of remediation agents in heterogeneous media where contaminants reside in hydraulically inaccessible zones.
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