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Denitrifying bioreactors: a solution to groundwater nitrate pollution at the Forge River?

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dc.contributor.advisor Swanson, Robert L. en_US
dc.contributor.author Gurdon, Christine Jean en_US
dc.contributor.other Department of Marine and Atmospheric Science en_US
dc.date.accessioned 2017-09-20T16:49:36Z
dc.date.available 2017-09-20T16:49:36Z
dc.date.issued 2015-12-01 en_US
dc.identifier.uri http://hdl.handle.net/11401/76187 en_US
dc.description 87 pgs en_US
dc.description.abstract Denitrifying bioreactors are an approach to remediate groundwater contaminated with nitrate. Their popularity as a remediation system has increased due to their unnecessary maintenance, low cost, and longevity. While field trials on their performance have been conducted, few have been completed in a marine coastal environment. In this study, a denitrification wall was designed to be installed and monitored along the shore of a coastal environment, namely, the Forge River, New York. Prior to the design phase, a groundwater plume of elevated nitrate-nitrite concentrations needed to be identified. Groundwater nitrate-nitrite concentrations ranged from 0.01-17.68 mg/L along Riviera Drive, a road running parallel to a tributary on the western side of the Forge River. Coarse wood chips were chosen as the carbon source for the denitrifying bioreactor and constant head tests were completed to choose an appropriate proportion of wood chips and sand (background soil), and to calculate the accompanying residence time. Mean hydraulic conductivity measurements were 249.70 cm/day (20% by volume wood chips), 333.50 cm/day (30% by volume wood chips), and 359.42 cm/day (40% by volume of wood chips). As the percent by volume of wood chips increased, the hydraulic conductivity did as well, but none were statistically higher than the site's soil. The residence time for each medium was calculated with widths of 0.1 m and 0.25 m. The residence times were 3.32 and 8.31 days (20% by volume of wood chips), 2.70 and 6.76 days (30% by volume of wood chips), and 2.51 and 6.27 (40% by volume of wood chips), increasing with width and decreasing with the percent by volume of wood chips. Due to previously observed nitrate removal rates (1.17-3.60 mg/L/day) and the location of elevated groundwater nitrate-nitrite concentrations, a medium consisting of 30% by volume of wood chips and 70% by volume of excavated soil was chosen for the denitrifying bioreactor. To capture the observed nitrate-nitrite plume, the bioreactor will need to be 47 m in length. Given the range in measured nitrate-nitrite concentrations, and the uncertainty in the nitrate removal rate, the bioreactor should have a width less than 0.25 m, perhaps closer to 0.1 m, to reduce the likelihood of other metabolic processes. At the well location, ideally the bioreactor would be installed as deep as 4.5 m below the surface, with the top residing at 3 m below the surface, to remove the most nitrate-nitrite and to reduce the likelihood of other metabolic processes. Nearer the tide line though, the bioreactor can be installed to shallower depths because the flow lines converge towards the surface. Wells should be installed on the seaward side of the bioreactor to monitor nitrate-nitrite, ammonium, methane, nitrous oxide, and dissolved organic carbon (DOC) concentrations, as well as pH and dissolved oxygen levels. en_US
dc.description.sponsorship This work is sponsored by the Stony Brook University Graduate School in compliance with the requirements for completion of degree. en_US
dc.format Monograph en_US
dc.format.medium Electronic Resource en_US
dc.language.iso en_US en_US
dc.publisher The Graduate School, Stony Brook University: Stony Brook, NY. en_US
dc.subject.lcsh Environmental science en_US
dc.subject.other denitrifying bioreactor, groundwater nitrogen, groundwater pollution, groundwater remediation, Long Island, wood chips en_US
dc.title Denitrifying bioreactors: a solution to groundwater nitrate pollution at the Forge River? en_US
dc.type Thesis en_US
dc.mimetype Application/PDF en_US
dc.contributor.committeemember Bokuniewicz, Henry en_US
dc.contributor.committeemember Brownawell, Bruce en_US

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