Sequential Zero-Valent Iron/Biofiltration Treatment of Landfill Gases: Influence of Gas Composition on BiofiltrationEPA Grant Number: U914981
Title: Sequential Zero-Valent Iron/Biofiltration Treatment of Landfill Gases: Influence of Gas Composition on Biofiltration
Investigators: Taylor, Denise G.
Institution: The Johns Hopkins University
EPA Project Officer: Carleton, James N
Project Period: January 1, 1996 through January 1, 2001
Project Amount: $102,000
RFA: STAR Graduate Fellowships (1996) RFA Text | Recipients Lists
Research Category: Fellowship - Environmental Engineering , Academic Fellowships , Engineering and Environmental Chemistry
The objectives of this research project are to: (1) determine the effects of high methane, high carbon dioxide, and low oxygen concentrations on the activity of the selected bacterial culture toward the target compounds; (2) determine whether biodegradation can be maintained when oxygen is supplied only intermittently to the biofilter stage; and (3) examine zero-valent iron dehalogenation of a chlorinated solvent in the gas phase.
This research project examines biodegradation under low oxygen conditions. Xanthobacter autotrophicus GJ10 is used as a model bacterial strain to degrade chlorinated compounds from landfill gas without consumption of the methane (a potential fuel product). It is an aerobic organism, but the reaction of its hydrolytic dehalogenase enzyme and the substrate does not require molecular oxygen (Janssen, et al., 1994). X. autotrophicus GJ10 was grown aerobically in nutrient broth (Difco). Cells were harvested by centrifugation, resuspended in a media containing no carbon source under an atmosphere of 97 percent N2 and 3 percent H2. Serum bottles (160 mL) were inoculated with 25 mL of the cell suspension and sealed under anaerobic conditions. 1,2-DCA was added by injection. Oxygenated bottles were similarly prepared, but under ambient air. Killed controls also were prepared under anaerobic conditions, using an autoclaved cell suspension. Headspace samples of 100 L were removed to analyze for 1,2-DCA by gas chromatography. Degradation of 1,2-DCA was observed in the anaerobic bottles (85 percent removal in 5 hours). Killed controls did not show significant loss of 1,2-dichloroethane (1,2-DCA). The fastest loss of 1,2-DCA occurred in the aerobic bottles (98 percent removal in 5 hours).