Proof-of-Concept Study: Novel Microbially-Driven Fenton Reaction for In Situ Remediation of Groundwater Contaminated With 1,4-Dioxane, Tetrachloroethene (PCE) and Trichloroethene (TCE)
ER-2305
Objective
Recent concern over 1,4-dioxane contamination in groundwater is driven by several factors, including the extensive use and improper disposal of 1,4-dioxane in industrial processes, the high mobility of 1,4-dioxane in water, the recalcitrance of 1,4-dioxane to degradation in the environment, and the classification of 1,4-dioxane as a probable human carcinogen. Current 1,4-dioxane remediation technologies generally entail ex situ pump-and-treat procedures that are not cost effective and are unable to remove co-contaminants such as tetrachloroethene (PCE) and trichloroethene (TCE). Cost-effective remediation technologies for in situ removal of 1,4-dioxane and co-contaminants PCE and TCE have yet to be fully developed. The objective of this limited-scope project is to demonstrate proof-of-concept that 1,4-dioxane and co-contaminants PCE and TCE are degraded simultaneously via application of a novel microbially-driven Fenton reaction.
Technical Approach
The novel microbially-driven Fenton reaction is driven by the O2-and Fe(III)-reducing microorganism Shewanella oneidensis. The researchers previously used S. oneidensis to drive a Fenton reaction-based, HO. radical generating system that degraded pentachlorophenol (PCP), a highly toxic chlorinated compound also widely distributed in contaminated groundwater. In the PCP degradation system, S. oneidensis batch cultures were provided with Fe(III) and exposed to alternating aerobic-anaerobic conditions. During the aerobic phase, S. oneidensis reduced O2 to H2O2, while during the anaerobic phase, S. oneidensis reduced Fe(III) to Fe(II). During the aerobic-to-anaerobic transition period, the produced Fe(II) and H2O2 interacted chemically via the Fenton reaction to form Fe(III), OH- ion, and HO. radical which, in turn, oxidatively dechlorinated PCP. The PCP degradation system was autocatalytic since continual inputs of Fe(II) and H2O2 were not required to drive PCP degradation. Fe(III) produced by H2O2-catalyzed Fe(II) oxidation was readily re-reduced back to Fe(II) by S. oneidensis in subsequent anaerobic phases. The researchers also employed the S. oneidensis-driven Fenton system to depolymerize lignocellulosic materials that are used as inexpensive starting materials for biofuel production.
Based on these initial findings, the researchers hypothesized that the S. oneidensis-driven Fenton system may oxidatively degrade 1,4-dioxane and co-contaminants PCE and TCE. Recent results demonstrate that 1,4-dioxane is degraded in a manner analogous to PCP and the lignocellulosic materials. To test the hypothesis that the S. oneidensis-driven Fenton system simultaneously catalyzes the degradation of 1,4-dioxane and co-contaminants PCE and TCE, this project is divided into two major tasks: (i) optimization of rates of 1,4-dioxane, PCE, and TCE degradation in batch reactor configurations, and (ii) demonstration of 1,4-dioxane, PCE, and TCE degradation under advective flow conditions in packed flow through columns.
Benefits
Results of this proof-of-concept study will provide background data for extending the innovative technologies capable of simultaneously degrading 1,4-dioxane and co-contaminants PCE and TCE to field applications where the approach should be equally effective in source zones and in low-concentration plumes. (Anticipated Project Completion - 2014)
Points of Contact
Principal Investigator
Dr. Thomas DiChristina
Georgia Institute of Technology
Phone: 404-894-8419
Fax: 404-385-4440
Document Types
- Fact Sheet - Brief project summary with links to related documents and points of contact.
- Final Report - Comprehensive report for every completed SERDP and ESTCP project that contains all technical results.
- Cost & Performance Report - Overview of ESTCP demonstration activities, results, and conclusions, standardized to facilitate implementation decisions.
- Technical Report - Additional interim reports, laboratory reports, demonstration reports, and technology survey reports.
- Guidance - Instructional information on technical topics such as protocols and user’s guides.
- Workshop Report - Summary of workshop discussion and findings.
- Multimedia - On demand videos, animations, and webcasts highlighting featured initiatives or technologies.
- Model/Software - Computer programs and applications available for download.
- Database - Digitally organized collection of data available to search and access.