The Development of Anaerobic Bioremediation Approaches for Chlorinated Solvent and 1,4-Dioxane Co-Contaminated Sites

Dr. Alison Cupples | Michigan State University

ER-2712

Objective

This research focuses on improving the remediation strategies for sites with mixed contamination. The goal is to develop methods that can be used in parallel to address the DoD’s most commonly found contaminants in co-existing plumes. The work concerns mixed contamination with 1,4-dioxane and the chlorinated solvents (trichloroethene, dichloroethene, vinyl chloride and 1,1,1-trichloroethane). Bioremediation has emerged as an important remediation approach for the chlorinated solvents. As the key species involved (Dehalobacter and Dehalococcoides spp..) are only viable under reducing conditions (e.g. sulfate reducing, methanogenic), any approach to address 1,4-dioxane co-contamination also must be viable under such conditions.

The overall objective of this proof-of-concept project is to develop an anaerobic mixed culture capable of 1,4-dioxane biodegradation as well as the reductive dechlorination of the chlorinated solvents.

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Technical Approach

The research is designed with three laboratory tasks and will ultimately involve the use of commercially available bioaugmentation cultures (e.g. SDC-9™). The first task will develop microcosms capable of degrading 1,4-dioxane under reducing conditions (iron reducing, sulfate reducing or methanogenic). These experiments will involve the examination of a range of inoculum sources (agricultural soil, wastewater samples, bioreactor samples) to ensure a wide spectrum of microbial communities are investigated. Following this, Task 2 concerns the development of enrichment cultures to create a high concentration of 1,4-dioxane degraders. Additionally, this task will involve the identification of the microorganisms responsible for 1,4-dioxane degradation using high throughput sequencing. The third task will examine co-contaminant (chlorinated solvents and 1,4-dioxane) removal rates by the 1,4-dioxane enrichment cultures and commercially available bioaugmentation cultures. For this, different 1,4-dioxane enrichment cultures will first be mixed with SDC-9™ to determine 1,4-dioxane degradation rates and chlorinated ethene reduction rates. If time permits, the enrichment cultures also will be mixed with the commercially available mixed culture, TCA-20™, to examine removal when 1,1,1-trichloroethane is present.

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Benefits

There is a critical need to develop management strategies for 1,4-dioxane due to its widespread occurrence. This chemical, a probable human carcinogen, was commonly used as a stabilizer in 1,1,1-trichloroethane formulations and is now frequently detected at sites where chlorinated solvents are present. A major challenge in addressing 1,4-dioxane contamination concerns chemical characteristics that result in migration and persistence. Also, traditional remediation methods such as air stripping or activated carbon are largely ineffective with this compound. This research aims to develop 1,4-dioxane remediation methods relying on biological removal. The expected benefits to DoD involve the development of a remediation approach to address mixed contamination plumes containing 1,4-dioxane and the chlorinated solvents. The research builds on remediation methods already commonly used for the chlorinated solvents. Therefore, the approach for mixed contamination is likely to be cost-effective and sustainable. Although this work is at the bench scale, if the results are positive, the approach could be easily tested at the pilot and full scale. (Anticipated Project Completion - 2019)

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Points of Contact

Principal Investigator

Dr. Alison Cupples

Michigan State University

Phone: 517-432-3370

Fax: 571-355-0250

Program Manager

Environmental Restoration

SERDP and ESTCP

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