Pilot Test of Bioaugmentation for Treatment of 1,4-Dioxane in Mixed Contaminant Source Zone

Abstract

1,4-Dioxane is widely associated with chlorinated solvent source-zones/plumes and presents a significant remediation challenge due to its high mobility and persistence. Geochemical conditions that are suitable for chlorinated solvent degradation (e.g., strongly reducing conditions) are generally incompatible with 1,4-dioxane degradation. Direct metabolism of 1,4-dioxane may be feasible under aerobic conditions but requires specific bacteria that are often not naturally occurring.

This presentation will focus on an industrial site in the southeast United States. The source area is impacted with mixed constituents including chlorinated solvents, hydrocarbons, and 1,4-dioxane. Under ambient conditions there is a robust microbial community with both aerobic and anaerobic biomarkers. While natural attenuation appears to be occurring, engineered methods are being evaluated to expedite treatment.

An aerobic bioremediation pilot test was started in the summer of 2022 to investigate direct metabolism with use of a biosparge system and delivery of SiREM’s DXO-88TM bioaugmentation culture. Performance assessment included groundwater sampling for VOCs, 1,4-dioxane, geochemical parameters, and microbial community evaluation (qPCR and NextGen sequencing). Data collection to date indicates that the conditions amenable to degradation of 1,4-dioxane are becoming established. Data available through fall 2023 indicates 1,4-dioxane concentration reductions of 50% to 90% have been attained after 16 months of system operation. The results suggest that bioaugmentation is a feasible remedy for 1,4-dioxane source areas.

SiREM supports field application of bioaugmentation cultures like the described pilot test above. Effective implementation of bioaugmentation cultures at complex sites are additionally supported by bench scale treatability studies and molecular genetic testing. Treatability studies can be used to evaluate bioaugmentation cultures as well as other remedial technologies with samples from the Site to provide insight into field performance. Sandra’s presentation will provide additional information on the DXO-88TM bioaugmentation culture, the molecular targets of interest, and highlight where treatability studies provide value for 1,4-dioxane remedies.

The Presenters

Fritz Krembs, P.E., P.G.Senior Engineer
Fritz Krembs is a senior engineer at Trihydro Corporation with over 20 years’ experience. Fritz holds a Master’s in Environmental Engineering from Colorado School of Mines and a Batchelor’s in Geology from Haverford College. He is a registered Professional Engineer and Professional Geologist. He has contributed to ESTCP publications and has been active in several ITRC teams most recently that focused on 1,4-dioxane. While patiently waiting for PFAS issues to become all-consuming he has focused on understanding the fate, transport, and management of organic compounds in groundwater systems with a focus on in-situ bioremediation, in-situ chemical oxidation, and monitored natural attenuation.
Sandra Dworatzek, M.Sc.Principal Scientist
Sandra is a Principal Scientist with more than 25 years’ experience in bioremediation of chlorinated solvents, petroleum hydrocarbons, emerging contaminants and other recalcitrant compounds. She has specific technical experience in the design of laboratory treatability studies, the scale up of growth of aerobic and anaerobic microbial cultures for bioaugmentation laboratory and field pilot tests, and evaluation of aerobic and anaerobic bioremediation, zero valent iron and chemical oxidation technologies in the laboratory. She currently provides senior technical oversight of laboratory treatability studies and the development and scaleup of new bioaugmentation cultures, including novel cultures for BTEX compounds under anaerobic conditions and aerobic 1,4-dioxane bioremediation. Sandra currently is the industry lead on a Genome Canada funded project for the commercialization of anaerobic BTEX degrading cultures.