WORKING SMARTER, NOT HARDER: USING VISCOUS POLYMER SOLUTIONS TO ACHIEVE INCREASED CONTAMINANT DESTRUCTION IN HETEROGENEOUS AQUIFERS

Several techniques for the in-situ destruction of organic groundwater contaminants have been refined over the past few decades, including but not limited to biodegradation applications and chemical oxidant treatments. One implementation difficulty common to these techniques is the effective delivery of treatment agents, which is often adversely affected by the heterogeneous nature of many aquifer systems. One way to increase the amendment-contacted volume of the aquifer involves the use of viscous polymer solutions that inhibit the development of preferential flow pathways. The shear-thinning rheology of these solutions allows them to effectively access more lower-permeability zones in a given volume than do typical water-based solutions with low (~1 cP) viscosity. A brief overview of the mechanism behind this process will be presented, along with issues pertaining to polymer-amendment compatibility. We will also present the results of bench-scale experiments contrasting the efficiency of contaminant destruction in lower-permeability regions using polymer-enhanced (high viscosity) and conventional (aqueous, low viscosity) applications of chemical oxidants. In dual-permeability systems involving organic contaminant within and downstream of lower-permeability media, polymer/oxidant mixtures were able to penetrate the lower-permeability lens in fewer pore volumes and effected a greater contaminant destruction than did an aqueous injection of equal mass. In addition, experiments comparing the effectiveness of two differing polymer-enhanced injection strategies (co-injection of polymer and oxidant versus unmixed in-series injections) are presented, with the data strongly supporting the need for aboveground mixing. These findings and other experimental results will provide a basis for future larger-scale field implementation of polymer-enhanced chemical oxidation.