Date of Award
Master of Science (MS)
Environmental Engineering and Earth Sciences
Chlorinated solvents are a widespread groundwater contaminant across the United States and worldwide. Bioremediation strategies for chlorinated solvents in groundwater environments often involve electron donor amendments to stimulate reductive dechlorination.
Electron donor amendment technologies have evolved over time, utilizing varying lipid or carbohydrate based compounds. Several popular electron donor amendments contain soybean based emulsified vegetable oil (EVO), or low molecular mass organic acid compounds including acetate and formate. This project seeks to develop a group of novel electron donor amendments based on animal co-products to outperform conventional products. These co-products are comprised of waste generated in the animal rendering process such as feathers or bone. The now patented technology will lead to considerably lower cost electron donor amendments compared to commonly used substrates.
Experiments were conducted in a batch setting on a laboratory scale. Serum bottles were assembled with 50 grams of sediment collected from a local site contaminated with trichloroethylene (TCE). The bottles were dosed with various animal co-products at different concentrations (3.2mg/L – 1g/L). Additionally, 20 ml of aquifer water and 20 Mols of TCE were added to each bottle. Bottles were then sealed and headspace was replaced with nitrogen. Control bottles were assembled with no electron donor, Lactate, and EOS. Headspace samples were taken on a weekly basis, and dechlorination was measured using gas chromatography-mass spectrometry. Measurements continued until stoichiometric ethene generation was observed (our operationally defined point of “success”).
Further batch experiments were then conducted based on results of feasibility experiments. These experiments focused on optimization of co-product concentration, utilizing mixtures of different co-products, and replicating feasibility with diverse soil samples.
The data collected in this project highlight the potential for animal co-products to be utilized as a novel electron donor for in-situ chlorinated solvent remediation. Many co-products rendered for this study display comparable dechlorination rates to lactate and EOS controls. Mixtures of co-products also display similar dechlorination rates compared to controls.
Further research of these co-products could lead to significantly lower cost electron donor amendment strategies. Traditional soybean based electron donors cost between $0.25-3.00 per pound, while animal co-products based electron donors cost between $0.005-0.225 per pound. Considering many sites may require thousands of pounds of electron donor amendment, the savings potential is significant. Furthermore, by lowering the cost of the electron donor substrate, many more sites could potentially benefit from access to this technology.
Houston, John K., "Rendering Co-Products as Electron Donors for Subsurface Remediation" (2020). All Theses. 3391.