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Resource Library > Technology Transfer > Programs and Initiatives > Enhanced In Situ Anaerobic Bioremediation > Resources


Featured Document: AFCEE, 2008. Technical Protocol for Enhanced Anaerobic Bioremediation Using Permeable Mulch Biowalls and Bioreactors.
Permeable mulch biowalls are an increasingly employed approach to applying enhanced in situ anaerobic bioremediation. A biowall trench physically cuts though and removes a portion of the aquifer matrix, allowing for uniform distribution of substrate and contact with contaminated groundwater flowing through the biowall treatment zone. Biowall substrates are typically low cost materials such as mulch and compost, and common construction materials such as sand and gravel are used to prevent compaction and maintain permeability. Biowall materials may be modified to include amendments to stimulate both biotic and abiotic degradation processes, allowing the practitioner to optimize biowall performance based on the type of contaminant(s) present and the desired degradation pathway(s) to be stimulated. The technology may also be applied in source areas or to capture "deeper" (e.g., greater than 35 feet bgs) plumes in an in situ bioreactor configuration using recirculation of groundwater.

Permeable mulch biowalls and in situ bioreactors hold great promise as a remedy for shallow groundwater contaminant plumes and some source areas. This technical protocol has been prepared by the AFCEE to provide guidance to AFCEE and their DoD technology-transition partners on the evaluation, design, and implementation of permeable mulch biowalls and bioreactors for enhanced in situ bioremediation of contaminants subject to anaerobic transformation in groundwater.

Featured Document: AFCEE, NFESC, ESTCP. 2008. Workshop on In Situ Biogeochemical Transformation of Chlorinated Solvents. AFCEE, Brooks City-Base, TX, USA; Naval Facilities Engineering Service Center Port Hueneme, CA, USA; and Environmental Security Technology Certification Program, Arlington, VA, USA. February. Prepared by CDM, Seattle, WA, USA. Workshop on In Situ Biogeochemical Transformation of Chlorinated Solvents
A workshop was held in San Antonio, Texas, from April 24 - 26, 2007, to promote an active discussion of ongoing research focused on the role of in situ biogeochemical transformation of chlorinated solvents. The workshop was convened to discuss the current understanding of this process and identify research and demonstration needs among researchers, practitioners, site owners, and regulatory agencies. The participants identified key issues in each of the following topic areas: Fundamental understanding of in situ biogeochemical transformation; Characterization of in situ biogeochemical transformation; Implementation of remediation systems based on in situ biogeochemical transformation; Regulatory acceptance of remediation using in situ biogeochemical transformation. Based on the key issues, research and demonstration needs were identified for remediation of chlorinated solvents using in situ biogeochemical transformation. In total, seven research and two demonstration needs were identified, with most of them focused on improving the fundamental understanding of mechanisms and processes that contribute to chlorinated solvent degradation.
In situ biogeochemical transformation is a promising remediation technology that operates at the interface of physical, chemical, and biological phenomena. The interdisciplinary nature of environmental science and engineering has fostered cognizance of the power of this interface and will be a critical component in further development and application of this innovative technology. Future application of in situ biogeochemical transformation will result in more cost-effective ways of mitigating the risks associated with inorganic and organic contamination of soil, groundwater, and sediment. Download the Workshop report.

Featured Document: AFCEE, 2007. Protocol for In Situ Bioremediation of Chlorinated Solvents Using Edible Oil
The addition of pure liquid edible oil and edible oil emulsions, referred to as the edible oil process, has been used to stimulate the in situ anaerobic biodegradation of chlorinated solvents and related contaminants at commercial, industrial and military sites throughout the United States. The protocol presented in this document is intended to assist base managers and project engineers in 1) determining if the edible oil process is appropriate for their site; 2) designing and implementing an edible oil engineered system; and 3) evaluating and optimizing remedial performance over time. This protocol also provides background information on the development and scientific basis of this technology.

PRINCIPLES AND PRACTICES

Principles and Practices of Enhanced Anaerobic Bioremediation of Chlorinated Document.  Overview Presentation
Although enhanced in situ anaerobic bioremediation has been applied at hundreds of sites to date, it has yet to gain widespread regulatory acceptance as a proven technology primarily due to unfamiliarity with the technology and a lack of consistency in achieving remedial objectives. Therefore, the objectives of the Principles and Practices document are to describe the scientific basis of enhanced in situ anaerobic bioremediation and to summarize relevant site selection, design, and performance criteria for various engineered approaches to stimulate and enhance in situ biodegradation of chlorinated solvents. The document is not intended as a protocol to implement enhanced bioremediation. Rather, the document provides the information necessary to make informed decisions as to when enhanced in situ anaerobic bioremediation is appropriate, and what specific enhanced bioremediation approaches may be suitable for achieving remedial goals.

Intended Audience
The Principles and Practice document is intended to provide DoD restoration project managers (RPMs) and their contractors with the information necessary to make informed decisions on using enhanced in situ anaerobic bioremediation as a treatment technology for chlorinated solvents in groundwater. This document provides the RPM with the tools required to assess the application of enhanced anaerobic bioremediation at their sites and to identify optimum approaches, particularly when soliciting and reviewing enhanced bioremediation services.

Using the Principles and Practices Document
The Principles and Practices document is essentially divided into three parts, including an overview of enhanced in situ anaerobic bioremediation (Section 1), a description of the science and principles of anaerobic bioremediation (Section 2), and the steps required to practice and evaluate the technology (Sections 3 through 6). This section introduces the reader to the document and provides a condensed overview of enhanced in situ anaerobic bioremediation of chlorinated solvents. Section 2 provides a more detailed description of the "principles" of anaerobic biodegradation for those who desire more insight into the science of enhanced in situ anaerobic bioremediation, including degradation processes and geochemical and microbial considerations.

There are three parts to this Principles and Practices of Enhanced Anaerobic Bioremediation document:
  • Part 1. Introduction and Technology Overview (Section 1)
  • Part 2. Principles of the science of enhanced bioremediation (Section 2)
  • Part 3. State of the practice of enhanced bioremediation (Sections 3 through 6)
Sections 3 through 6 summarize the "practice" of enhanced bioremediation. The reader who has sufficient knowledge of the science and wishes to screen the technology for applicability at a given site may go directly to Section 3, Preliminary Screening. The authors caution that use of the preliminary

screening section does require some subjective judgment, and the user should first consider reading Section 2. Section 4 provides predesign considerations and describes tools used to evaluate application of the technology once preliminary screening has been conducted, but before proceeding with system design. Section 5 provides design and engineering considerations, while Section 6 provides considerations for system monitoring and performance evaluation.

Section 7 contains references cited in the text of the document. Appendix A contains contact information for key project personnel involved in the generation of this document, including technical contributors and reviewers. Appendix B contains a sample contractual statement of work for RPMs who may need to solicit enhanced in situ anaerobic bioremediation services. Appendix C provides a list of common anaerobic biodegradation reactions and a description of approximation techniques commonly used to determine substrate demand. Appendix D is an evaluation of alternative enhanced anaerobic bioremediation systems, while Appendix E contains example case studies for several substrate types.

Work Plans
Reports Articles, Abstracts, and Papers Presentations
  • Principles and Practices of Enhanced Anaerobic Bioremediation of Chlorinated Solvents Presentation.
  • Many presentations regarding Enhanced In Situ Bioremediation can be found on the AFCEE Technology Transfer Workshop web page. The web page includes both presentations and extended abstracts from the 2001, 2002, 2003, and 2004 Workshops.
  • TCE Plume Management through Edible Oil Injection and Natural Attenuation. 2004. Poster. Extended Abstract.
  • Cost Estimating Tool for Enhanced Anaerobic Bioremediation. 2004. Presentation.
  • Tri-Services Enhanced Anaerobic Bioremediation Principles and Practices Document. 2004. Poster.
  • Biogeochemical Treatment of Chlorinated Ethenes. 2003. Presentation.
  • Aqueous and Mineral Intrinsic Bioremediation Assessment: Results from Three Sites. 2003. Poster.
Cost Estimating Tool
  • Files for the Cost Estimating Tool for Enhanced Anaerobic Bioremediation of Chlorinated Solvents are available free for download.

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