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2007 Ground Water Summit |
Wednesday, May 2, 2007 : 8:20 a.m.
Polymer-Oxidant Compatibility for Use as a Combined Ground Water Remediation Treatment
Polymer floods, commonly used in the oil industry to enhance recovery in low-permeability or heterogeneous aquifers, have potential for use in groundwater remediation treatments. Due to their increased viscosity over that of groundwater, polymer floods encourage flow between layers of differing permeability. In combination with other contaminant-destruction techniques, polymer solutions could improve the efficiency of the treatment, by causing the remediation agents to more effectively reach difficult-to-treat areas. One promising combination is that of in situ chemical oxidation (ISCO) and safe, food-grade polymer floods. For example, chlorinated solvents are effectively treated by ISCO, but the short reaction time requires that oxidants be applied near or circulated to the contaminant source. If the ISCO treatment does not reach contaminants in low-permeability areas, post-treatment diffusion can cause “rebound” contamination. Polymer solutions, injected in series or co-injected, would increase the viscosity of the remediation treatment, causing flow into previously unreached areas. Before we fully test this combination at the laboratory scale, however, the compatibility of polymers and the accompanying remediation agents must be explored. We present the results of 72-hour polymer-oxidant compatibility tests which suggest that food-grade polymers (xanthan and polyacrylamide) are chemically compatible with two common oxidants (potassium permanganate and sodium persulfate). The oxidant demand for the polymers is generally low such that the oxidant’s destructive capabilities are maintained, while viscosity differences, which are crucial for promoting better delivery efficiency, can be maintained over a period of days. The results of these tests thus allow us to optimize future laboratory tests to determine if this combination is indeed a feasible treatment option for sites contaminated with chlorinated solvents.