Classified as a likely human carcinogen, 1,4-dioxane has been found at numerous chlorinated solvent-contaminated sites throughout the United States. Combined physical and chemical properties, along with the behavior of 1,4-dioxane, create ongoing challenges for both its characterization and treatment. Over the years, many scientists have searched, but none have found a convincing path to biodegradation of 1,4-dioxane in the absence of oxygen. This lack of evidence has resulted in many experts wondering if anaerobic biodegradation of 1,4-dioxane truly exists.
Recent research by Ramalingam and Cupples (2020)1 showed that the long-sought but elusive anaerobic biodegradation of 1,4-dioxane occurs under extreme methanogenic reducing conditions (that’s oxidation-reduction potential (ORP) values of less than -200 mV (against Ag/AgCl electrode).
Conventional thinking that usually relies on separate remedies for 1,4-dioxane and its chlorinated solvent counterparts may soon be changing to a new paradigm that involves a single synergistic remedy: anaerobic biostimulation with bioaugmentation. These findings provide hope that chlorinated solvents and 1,4-dioxane in groundwater can be removed at the same time and space with conventional anaerobic biostimulant and cultured bacteria injection strategies. Knowing that an anaerobic counterpart to aerobic 1,4-dioxane bioremediation is finally emerging may help to shape (or reshape) remediation strategies that shift toward less expensive passive remedies and away from more expensive conventional active remedies like pump-and-treat.
The research by Ramalingam and Cupples is sure to inspire further research toward isolation and cultured growth of anaerobic 1,4-dioxane-degrading microorganisms. If the history of remediation bacteria cultures containing aerobic 1,4-dioxane-degrading microorganisms (like CB1190) is a guide, then commercial remediation cultures containing anaerobic 1,4-dioxane degraders could be on the way in just a few years.
If you would like to discuss 1,4-dioxane remediation in more detail, EHS Support’s team of subject matter experts are here to help:
Will Harms, In-Situ Remediation Services Practitioner
Laurel Seus, Remediation Microbiologist
John Bartos, Senior Remediation Hydrogeological Engineer
Rich Landis, Senior Innovative Technologies Practitioner
1Source: Ramalingam, V., Cupples, A.M. Anaerobic 1,4-dioxane biodegradation and microbial community analysis in microcosms inoculated with soils or sediments and different electron acceptors. Appl Microbiol Biotechnol 104, 4155–4170 (2020). https://doi.org/10.1007/s00253-020-10512-3