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United States Department of Agriculture

Agricultural Research Service

Title: A New Soil C/n Module to Simulate Denitrification for Groundwater Remediation

Authors
item Ma, Liwang
item Hunter, William
item Ahuja, Lajpat

Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: May 9, 2005
Publication Date: November 6, 2005
Citation: Ma, L., Hunter, W.J., Ahuja, L.R. 2005. A new soil C/N module to simulate denitrification for groundwater remediation. ASA-CSSA-SSSA Annual Meeting Abstracts. Nov. 6-10, 2005. Salt Lake City, UT.

Interpretive Summary: Permeable denitrifying barriers with injected vegetable oil have shown promise for removing nitrate from contaminated groundwater. The carbon/nitrogen (C/N) module in Root Zone Water Quality Model (RZWQM) has been improved and modularized for easy implementation. This module was used to simulate the denitrification process in the barriers as affected by vegetable oil content. The denitrification process was divided into two sub-processes in the module: nitrate to nitrite and nitrite to N2O and N2. Each sub-process was simulated as a first-order kinetics that was a function of available substrates and denitrifier population. The growth of denitrifier population was controlled by available organic carbon and available nitrogen to maintain appropriate C:N ratio for microbial biomass. The new denitrification module was coupled to the convective-dispersive equations for nitrate and nitrite transport, and was tested against a series of laboratory column studies, where saturated flow was maintained and various amounts of vegetable oils were injected. Simulation results showed that the model correctly simulated the capacity of the columns to remove nitrate from flowing water with different amounts of oil injection. Key words: RZWQM; Modeling; Biobarrier; Contamination; Bioremediation.

Technical Abstract: Permeable denitrifying barriers with injected vegetable oil have shown promise for removing nitrate from contaminated groundwater. The carbon/nitrogen (C/N) module in Root Zone Water Quality Model (RZWQM) has been improved and modularized for easy implementation. This module was used to simulate the denitrification process in the barriers as affected by vegetable oil content. The denitrification process was divided into two sub-processes in the module: nitrate to nitrite and nitrite to N2O and N2. Each sub-process was simulated as a first-order kinetics that was a function of available substrates and denitrifier population. The growth of denitrifier population was controlled by available organic carbon and available nitrogen to maintain appropriate C:N ratio for microbial biomass. The new denitrification module was coupled to the convective-dispersive equations for nitrate and nitrite transport, and was tested against a series of laboratory column studies, where saturated flow was maintained and various amounts of vegetable oils were injected. Simulation results showed that the model correctly simulated the capacity of the columns to remove nitrate from flowing water with different amounts of oil injection. Key words: RZWQM; Modeling; Biobarrier; Contamination; Bioremediation.

Last Modified: 10/25/2014