Duane Graves, PhD. (TN), coauthored a paper entitled “Enhanced bioremediation of RDX and Co-Contaminants perchlorate and nitrate using an anaerobic dehalogenating consortium in a fractured rock aquifer” published in Chemosphere.
Michelle Lorah (U.S. Geological Survey, MD) was the lead author and the coauthors in addition to Duane included Eric Vogler & Fredrick Gebhardt (U.S. Geological Survey, NM) and Jennifer Fedorowski Grabowski (University of Maryland Baltimore County, MD).
Duane is the US Operations Manager at SiREM with over 30 years of experience focused on environmental biotechnology; environmental forensics; in situ groundwater, soil and sediment remediation; evaluation of airborne biological contaminants; and remediation of groundwater. His practice at SiREM specializes in (i) the development, selection, feasibility evaluation, design and deployment of remedial solutions of hazardous and mixed-waste treatability for complex process engineering and wastewater; (ii) biogeochemical evaluations related to metals attenuation, and (iii) investigation and mitigation of biological agents. Duane also provides expert opinions and testimony to support litigation regarding environmental chemistry, remediation, and microbiology associated with the transport and fate of organic, organochlorine, and inorganic chemicals and metals in sediment, soil, and groundwater; environmental forensics; liability allocation; remediation; and environmental technology issues.
Chemosphere is an international journal designed for the publication of original communications as well as review articles on chemicals in the environment. Chemosphere, as a multidisciplinary journal, offers maximum dissemination of investigations related to all aspects of the identification, quantification, behavior, fate, toxicology, treatment, and remediation of chemicals in the bio-, hydro-, litho- and atmosphere.
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Published Abstract
The potential neurotoxic and carcinogenic effects of the explosives compound RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) on human health requires groundwater remediation strategies to meet low cleanup goals. Bioremediation of RDX is feasible through biostimulation of native microbes with an organic carbon donor but may be less efficient, or not occur at all, in the presence of the common co-contaminants perchlorate and nitrate. Laboratory tests compared biostimulation with bioaugmentation to achieve anaerobic degradation of RDX, perchlorate, and nitrate; a field pilot test was then conducted in a fractured rock aquifer with the selected bioaugmentation approach. Insignificant reduction of RDX, perchlorate, or nitrate was observed by the native microbes in microcosms, with or without biostimulation by addition of lactate. Tests of the RDX-degrading ability of the microbial consortium WBC-2, originally developed for dehalogenation of chlorinated volatile organic compounds, showed first-order biodegradation rate constants ranging from 0.57 to 0.90 per day (half-lives 1.2 to 0.80 days). WBC-2 sustained degradation without daughter product accumulation when repeatedly amended with RDX and lactate for a year. In microcosms with groundwater containing perchlorate and nitrate, RDX degradation began without delay when bioaugmented with 10% WBC-2. Slower RDX degradation occurred with 3% or 5% WBC-2 amendment, indicating a direct relation with cell density. Transient RDX daughter compounds included methylene dinitramine, MNX, and DNX. With WBC-2 amendment, nitrate concentrations immediately decreased to near or below detection, and perchlorate degradation occurred with half-lives of 25–34 days. Single-well injection tests with WBC-2 and lactate showed that the onset of RDX degradation coincided with the onset of sulfide production, which was affected by the initial perchlorate concentration. Biodegradation rates in the pilot injection tests agreed well with those measured in the microcosms. These results support bioaugmentation with an anaerobic culture as a remedial strategy for sites contaminated with RDX, nitrate, and perchlorate.
More Information
Learn more about the article: https://www.sciencedirect.com/science/article/abs/pii/S0045653522001679
Learn more about Journal: https://www.journals.elsevier.com/chemosphere
For consultation on Enhanced Bioremediation: dgraves@siremlab.com or jroberts@siremlab.com
Learn more about Duane: https://www.linkedin.com/in/duane-graves-a7b79b16/
