Peter Bennett

Principal Hydrogeologist
Haley & Aldrich

Mr. Bennett is a Principal Consultant at Haley & Aldrich. He has 23 years of experience with innovative site characterization and remediation projects. He has served as the project manager and technical lead for several Superfund sites and routinely assists his clients in reducing the costs and liabilities associated with old chemical releases. He has implemented low cost in-situ remediation programs at several sites as alternatives to groundwater extraction. Throughout his career, Mr. Bennett has played a major role in designing, testing, and implementing site-specific approaches for documenting the natural biodegradation of fuel hydrocarbons, chlorinated solvents and 1,4-dioxane.

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PLATFORM PRESENTATION
Microbial Chain Elongation: A more efficient process for promoting and sustaining in situ bioremediation of chlorinated solvents

Electron-donor substrates were tested at a site with groundwater recirculation to promote dehalorespiration of chlorinated ethenes. So-called “longer-lasting” substrates with emulsions had unacceptable unintended consequences; simple soluble substrates were more effective in the short-term but required frequent re-application. Microbial Chain Elongation (MCE) is an option to solve these problems. MCE occurs when certain microbes (C. kluyveri) build larger compounds (butyrate and caproate) by combining acetate and ethanol while producing diatomic hydrogen to support dehalorespiration, with minimal impact on pH and methane formation. Bench tests with site soil and groundwater samples indicated acetate + ethanol + C. kluyveri directly promoted dehalorespiration with less methane and carbonate production. The presence of C. kluyveri was confirmed in site soil samples but not in site groundwater samples. A push pull test was designed to pilot-test MCE for in situ bioremediation and inform on the full scale implementation and will be discussed in this presentation.