Date of Award

8-2018

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Environmental Engineering and Earth Sciences

Committee Member

Dr. Kevin Finneran, Committee Chair

Committee Member

Dr. Cindy Lee

Committee Member

Dr. Brian Powell

Abstract

The United States produces approximately 55 billion pounds of animal co-products in a year. These materials are what remains once cattle, chickens, and other animals are slaughtered and the food grade material is processed for consumption. Although a substantial amount of this waste is used in the pet food industry, it leaves thousands of pounds as true waste, without a market. Given the nature of co-products, these materials have high protein and lipid content, and these waste materials have the potential to be used as electron donors for microbial processes. Animal waste co-products used as electron donor for bioremediation could be an inexpensive alternative for the industry, while reducing the amount of waste sent to a landfill.

Batch incubations were used to screen 38 animal co-products, provided by renderers within North America. Batches were constructed using TCE-contaminated aquifer material, and each electron donor (co-product) was added as the sole electron donor. Each animal co-product was compared to five controls containing common electron donors (lactate, acetate + hydrogen, EOS) and a sterile and unamended control. TCE and its degradation products were measured using GC-FID.

The data demonstrate that, of the five controls, lactate was able to facilitate the complete dechlorination of TCE in approximately 45 days. Lactate was the most effective electron donor of the controls and as a result each animal co-product was compared to it. Of the 38 animal co-products, four promoted the dechlorination of TCE to ethene faster than lactate (approximately 35 days) and three promoted the dechlorination of TCE in the same amount of time as lactate. One material, dissolved air flotation sludge (DAF), dechlorinated TCE to ethene at a 1:1 stoichiometry faster than any commercially available lipid based electron donor (e.g. emulsified vegetable oil). The difference is that the co-product is available for pennies per pound, while commercial electron donors sell for dollars per pound in some cases, and cost is often the limiting factor in site closure.

Future research will include optimizing the concentration of the animal co-products. The goal of future research is to determine the lowest possible concentration of animal co-product that can be used to still achieve complete dechlorination. Future research will also include investigating the use of animal co-products as electron donors for the bioremediation of other contaminants.

Share

COinS