Date of Award

8-2016

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Environmental Engineering and Science

Committee Member

Dr. David Freedman, Committee Chair

Committee Member

Dr. James Henderson

Committee Member

Dr. Kevin Finneran

Committee Member

Dr. Ronald Falta

Abstract

In spite of decades of remediation activities, there are still thousands of industrial sites worldwide that are in need of clean-up. As remediation technologies have advanced, numerous sites have been successfully addressed. Many of the sites that still need attention are those at which complex mixtures of contaminants are present, making the development of clean-up strategies more challenging. The site (Area P) that is the subject of this thesis is located in one of the largest industrial facilities in South America. The area is characterized by comingled environmental impacts caused by petrochemical industries. The main objective of this research was to evaluate the interaction among chemicals of concern in Area P during biodegradation under aerobic and anaerobic conditions, as well as the potential impact of chemical oxidation products on biodegradation. The specific objectives were: 1) To evaluate the impact of 2,4-DNT, 4-IPA, 1,2-DCA, 1,4-dioxane, and products from chemical oxidation of source zone contaminants on the aerobic biodegradability of CB; 2) To evaluate the impact of 2,4-DNT, 4-IPA, 1,2-DCA, 1,4-dioxane, and products from chemical oxidation of source zone contaminants on the aerobic biodegradability of 1,2-DCB; 3) To evaluate the impact of 2,4-DNT, 4-IPA, 1,2-DCA, 1,4-dioxane, and products from chemical oxidation of source zone contaminants on the anaerobic biodegradability of 4-NT; and 4) To evaluate the impact of 2,4-DNT, 4-IPA, 1,2-DCA, 1,4-dioxane, and products from chemical oxidation of source zone contaminants on the anaerobic biodegradability of 2,6-DNT. The experimental approach was to develop enrichment cultures that aerobically biodegrade CB and 1,2-DCB and anaerobically biodegrade 4-NT and 2,6-DNT, and then expose these cultures to low and high concentrations of 2,4-DNT, 4-IPA, 1,2-DCA, 1,4-dioxane, and products of chemical oxidation from source zone contaminants. Based on the results of this research, the following conclusions are offered: 1) Aerobic biodegradation of CB and 1,2-DCB was demonstrated in microcosms using soil and groundwater from an industrial site in South America. The microcosms served as inoculum to develop enrichment cultures, which were subsequently used to assess the effect of co-contaminants on the rate and extent of CB and 1,2-DCB biodegradation. 2) Anaerobic biodegradation of 2,6-DNT and 4-NT was demonstrated in microcosms using soil and groundwater from an industrial site in Brazil. Lactate served as the electron donor and nitro group reduction was the only transformation observed. The microcosms served as inoculum to develop enrichment cultures; the 2,6-DNT enrichment was subsequently used to assess the effect of co-contaminants on the rate and extent of 2,6-DNT biodegradation. The rate of 4-NT transformation was too slow to permit development of the 4-NT enrichment to the point needed to evaluate co-contaminants. 3) Alkaline activated persulfate was effective in chemical oxidation of the contaminants at their maximum concentrations. The treatment that employed a stoichiometric dose was used to simulate the effect of chemical oxidation groundwater on biodegradation of CB, 1,2-DCB, 2,6-DNT, and 4-NT. Although higher than stoichiometric doses achieved more complete removal, the stoichiometric dose (28 g/g contaminant) is at the high end of what is deployed in situ. 4) 2,4-DNT, 4-IPA, 1,4-dioxane, and 1,2-DCA did not inhibit the rate or extent of aerobic CB biodegradation when these co-contaminants were present at their target high concentrations. Temporary inhibitory effects on the rate of CB biodegradation were observed in the presence of 10% (v/v) of the chemical oxidation groundwater from the stoichiometric treatment. The source of inhibition is not yet known but may be related to the organic products from partial chemical oxidation of the contaminants. COD analysis of the chemical oxidation groundwater suggests that the extent of contaminant mineralization was minor. 5) CB serves as a primary substrate for aerobic cometabolism of 2,4-DNT and 4-IPA, but not 1,4-dioxane or 1,2-DCA. This suggests that the aromatic oxygenases that are required for metabolism of CB are also reactive with 2,4-DNT and 4-IPA. This is an example of a positive co-occurrence of contaminants. 6) 2,4-DNT, 1,4-dioxane, and 1,2-DCA did not inhibit the rate or extent of 1,2-DCB biodegradation of 1,2-DCB when these co-contaminants were present at their target high concentrations. A temporary decrease in the rate of 1,2-DCB biodegradation occurred in the presence of 4-IPA at its target high concentration and with the 10% (v/v) chemical oxidation groundwater from the stoichiometric treatment.

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