Superfund Research Program
Improving the Treatment of Contaminated Aquifers by Developing Direct-Push Oxidant Candles with Pneumatic Circulators
Project Leader: Mark Christenson
Grant Number: R42ES022530
Funding Period: Phase II: September 2015 - September 2017
Clean water is one of the most basic societal needs in the world. Few situations incite more public outcry than when a community learns that their drinking water has been tainted. Two of the biggest threats to groundwater quality in the U.S. are contamination from either chlorinated solvents or petroleum. Left unattended, the size and scope of the problems associated with the release of these contaminants into the environment have only become exacerbated with time. In the past decade, significant efforts have been devoted to developing innovative remedial technologies to combat contaminated groundwater. One technology that is relatively mature is the injection of liquid oxidants into contaminated aquifers or in situ chemical oxidation (ISCO). Two roadblocks to successfully implementing ISCO treatments are when contaminants are located in low permeable layers and these finer textured zones do not readily accept liquid injections or when the aquifer is porous enough for liquid injections, but the cohesive properties of the chemical oxidant results in density-driven flow, thereby causing the oxidant to sink and not treat the desired target zone.
To address both problems, AirLift Environmental and the University of Nebraska developed slow-release oxidant-paraffin candles that, when inserted into low permeable zones, slowly dissolve and intercept the contaminant. To prevent the oxidant from migrating downward from the candles, pneumatic circulators were developed that aerate or release bubbles at the base of the candle and prevent the oxidant from sinking while greatly facilitating its horizontal distribution. AirLift's Phase I grant provided proof-of-concept that oxidant candles with aeration tips could be manufactured and installed with direct-push equipment and that this technology could be used to successfully treat contaminated groundwater. In this Phase II STTR grant, researchers are performing numerous on-site trials so that the efficacy of the direct-push candles can be quantified under a range of hydrological conditions. Additional field testing will allow AirLift to refine product design and installation procedures.