Bioaugmenting the poplar rhizosphere to enhance treatment of 1,4-dioxane.

1,4-Dioxane is a highly mobile and persistent groundwater pollutant that often forms large dilute plumes. Because of this, utilizing aggressive pump-and-treat and ex-situ technologies such as advanced oxidation can be prohibitively expensive. In this study, we bioaugmented the poplar rhizosphere with dioxane-degrading bacteria Mycobacterium dioxanotrophicus PH-06 or Pseudonocardia dioxanivorans CB1190 to enhance treatment of 1,4-dioxane in bench-scale experiments. All treatments tested removed 10 mg/L dioxane to near health advisory levels (<4 μg/L). However, PH-06-bioaugmented poplar significantly outperformed all other treatments, reaching <4 μg/L in only 13 days. Growth curve experiments confirmed that PH-06 could not utilize root extract as an auxiliary carbon source for growth. Despite this limitation, our findings suggest that PH-06 is a strong bioaugmentation candidate to enhance the treatment of dioxane by phytoremediation. In addition, we confirmed that CB1190 could utilize both 1,4-dioxane and root extract as substrates. Finally, we demonstrated the large-scale production of these two strains for use in the field. Overall, this study shows that combining phytoremediation and bioaugmentation is an attractive strategy to treat dioxane-contaminated groundwater to low risk-based concentrations (~1 μg/L).

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Copyright © 2020. Published by Elsevier B.V.

Déclaration de conflit d'intérêts

Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.