Dissertation
Bioaugmentation and phytoremediation to treat 1,4-Dioxane-contaminated groundwater
University of Iowa
Doctor of Philosophy (PhD), University of Iowa
Summer 2021
DOI: 10.17077/etd.005804
Abstract
1,4-Dioxane (dioxane) is a probable carcinogen and persistent groundwater pollutant often found comingled with chlorinated solvents (e.g., trichloroethylene, dichloroethylene, and trichloroethane). Because of dioxane’s high mobility in groundwater, dioxane plumes tend to be large and dilute. State-issued clean-up guidelines for dioxane are on the order of 1 µg/L and sometimes less. Reaching these low clean-up guidelines through remediation has proven to be particularly difficult and costly. Utilizing aggressive pump-and-treat and ex-situ technologies such as advanced oxidation (AO) on dilute dioxane plumes is often prohibitively expensive. This work evaluated bioaugmented phytoremediation, a promising, cost-effective clean-up strategy for dioxane-contaminated groundwater. This work confirmed phytoremediation by hybrid poplar removed dioxane to health advisory levels (~1 µg/L) in bench-scale experiments. In addition, bioaugmenting the rhizosphere of poplar plants with archetype dioxane-degrading strains Pseudonocardia dioxanivorans CB1190 and Mycobacterium sp. PH-06 significantly increased the rate of dioxane removal.
This work also identified Rhodococcus ruber 219 as a promising candidate for field bioaugmentation. With the addition of B-vitamins, the strain can sustain growth in dilute dioxane concentrations (<100 µg/L) and degrade dioxane to risk-based health advisory levels (~0.35 µg/L).
This work demonstrated that bioaugmented phytoremediation is a promising treatment alternative for dioxane-contaminated groundwater to achieve low concentrations (<1.0 µg/L). While challenges remain, the successful implementation of this strategy offers a cost-effective and green solution to a widespread threat to human health.
Details
- Title: Subtitle
- Bioaugmentation and phytoremediation to treat 1,4-Dioxane-contaminated groundwater
- Creators
- Reid A. Simmer
- Contributors
- Jerald Schnoor (Advisor)Craig Just (Committee Member)Gregory Lefevre (Committee Member)Jacques Mathieu (Committee Member)Timothy Mattes (Committee Member)
- Resource Type
- Dissertation
- Degree Awarded
- Doctor of Philosophy (PhD), University of Iowa
- Degree in
- Civil and Environmental Engineering
- Date degree season
- Summer 2021
- DOI
- 10.17077/etd.005804
- Publisher
- University of Iowa
- Number of pages
- xv, 133 pages
- Copyright
- Copyright 2021 Reid A. Simmer
- Language
- English
- Description illustrations
- color illustrations
- Description bibliographic
- Includes bibliographical references (pages 122-133).
- Public Abstract (ETD)
1,4-Dioxane (dioxane) is a synthetic chemical and common groundwater pollutant. Dioxane pollution is a significant issue as it is known to cause cancer in humans, even at low concentrations. Due to dioxane’s chemical properties and persistence in the environment, it is challenging and expensive to clean up. There is a widespread need for novel, cost-effective methods to treat dioxane-contaminated groundwater.
This work evaluates phytoremediation, or the use of trees, to uptake and treat dioxane-contaminated groundwater. In addition, this research considers bioaugmentation, or the addition of microorganisms that are capable of breaking down dioxane. Finally, it examines combining bioaugmentation and phytoremediation by adding microbes into the root zone of trees.
Through lab-scale experiments, this work demonstrated that combining bioaugmentation and phytoremediation enhances the removal of dioxane compared to either technology alone. It was further ascertained that adding inexpensive B-vitamins can significantly improve dioxane removal by microorganisms, especially vitamin B1 (thiamine). While challenges remain, bioaugmentation and phytoremediation offer a cost-effective and green solution to a widespread threat to human health.
- Academic Unit
- Civil and Environmental Engineering
- Record Identifier
- 9984124761302771
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