Protocol for Enhanced In Situ Bioremediation Using Emulsified Edible Oil
An in-depth discussion of the EOS® patented technology and its usefulness for site remediation is presented. Details of how the technology works, design considerations as well as strengths and limitations of the technology are presented.
Management of groundwater contaminated with chlorinated solvents, perchlorate, and explosives is one of the Department of Defense’s (DoD’s) greatest environmental challenges. Chlorinated solvents have been used for years in both the military and commercial sectors for cleaning and degreasing many products and equipment including aircraft engines, automobile and truck parts, electronic components, and clothing. Widespread use of these compounds has resulted in impacts to the environment. Because of their physical and chemical properties, most chlorinated solvents are relatively recalcitrant in the subsurface, are more difficult to access once they are in the ground, and take longer to remediate. Similarly, groundwater contaminated with perchlorate has become a major environmental issue for the DoD due to the use, release, and/or disposal of solid rocket fuel and munitions containing ammonium perchlorate. These releases have resulted in extensive contamination of groundwater supplies. Perchlorate is highly soluble in water and poorly sorbs to mineral surfaces.
The Strategic Environmental Research and Development Program (SERDP) and the Environmental Security Technology Certification Program (ESTCP) have funded numerous projects to develop and demonstrate new remediation technologies to address these contaminants. Two of these projects focus on the use of emulsified edible oil to enhance in situ anaerobic bioremediation of groundwater contaminants: SERDP Project ER-1205 “Development of Permeable Reactive Barriers Using Edible Oils” and ESTCP Project ER-0221 “Edible Oil Barriers for Treatment of Chlorinates Solvent- and Perchlorate-Contaminated Groundwater.” This protocol has been developed based on the information gained from these projects.
The objective of this protocol is to provide guidance on the use of emulsified edible oils for enhanced in situ anaerobic bioremediation. Edible oils have been applied at more than 60 commercial and military sites nationwide. Although emulsified oils are well demonstrated in the laboratory and the field, this technology continues to evolve. This protocol is based on the current state of practice at the time of writing.
Several other documents and projects complement this protocol. ESTCP funded development of “A Treatability Test for Evaluating the Potential Applicability of the Reductive Anaerobic Biological In Situ Treatment Technology to Remediate Chloroethenes” (i.e., the RABITT Protocol), which aids users in determining the site applicability of enhanced anaerobic bioremediation for chloroethene contamination in groundwater (Morse et al., 1998). The “Principles and Practices of Enhanced Anaerobic Bioremediation of Chlorinated Solvents” (i.e., the Principles and Practices document) published cooperatively by the Air Force Center for Environmental Excellence and the Naval Facilities Engineering Service Center (NFESC) describes the scientific basis of enhanced anaerobic bioremediation and summarizes relevant site selection, design, and performance criteria for various engineered approaches to stimulate and enhance in situ biodegradation of chlorinated solvents (AFCEE, 2004). AFCEE is also in the process of publishing a “Protocol for In situ Bioremediation of Chlorinated Solvents using Edible Oil” (i.e., the Edible Oils Protocol), which focuses on the application of pure liquid edible oils and edible oil emulsions to provide a long-lived carbon source to enhance anaerobic bioremediation of chlorinated solvents in groundwater. In addition, ESTCP is funding a separate project, ER-0319 “Sequestration of a DNAPL Source with Vegetable Oil,” to evaluate the use of pure vegetable oil to physically and chemically sequester DNAPLs in the short-term followed by enhanced biodegradation of dissolved contaminants in the long-term. These documents and projects are referenced throughout this protocol, as applicable.