Coupling Downhole Slow-Release Oxidant Candles with Airlift Recirc Wells

By: Will Harms, Bioremediation Services Practitioner

In Situ Chemical Oxidation (ISCO) remedies for groundwater contamination has evolved into a mature industry. Yet, effective and lasting use of ISCO suffers from two basic problems: 1) short oxidant lifespans, and 2) poor mixing in the subsurface.

Several years ago, novel downhole slow-release oxidant-infused paraffin wax ‘candles’ (similar to ordinary candles) emerged with the intention to overcome the common limitation of short-lived oxidants. However, slow-release oxidant candles did not always perform up to expectations because (drum roll please), you guessed it, insufficient mixing of dissolved oxidants into groundwater. One new method to improve performance of downhole slow-release oxidant-infused paraffin wax candles pairs well-known airlift recirculation wells with slow-release oxidant candles. The approach was commercialized by AirLift Environmental LLC . Results of their research and case studies is compelling enough for the National Institute of Environmental Health Sciences  to spotlight the coupled remedy in the recent Superfund Research Program Research Brief 315 dated March 4, 2021.

This new method is important because it holds promise to improve performance of ISCO initiatives at much lower cost compared to most of the conventional approaches used to deliver oxidants.

Sites that could most benefit from coupling downhole oxidant candles in airlift recirc wells are those that:

  1. Present low to moderate pollutant concentrations.
  2. Present low to very low groundwater velocities.
  3. Back-diffusion sources the contaminant plume.
  4. Are almost, but not quite, ready for a monitored natural attenuation component of a final remedy.

Site stakeholders benefit from awareness of new remedy approaches like this one because it enables better remediation decision-making.

Contact Will Harms and our team of experts to learn how EHS Support can help you navigate the latest remedy approaches that may be a candidate for effective and cost-effective use at your site.

View a video by AirLift Environmental LLC can be found here.

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