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Modeling enhanced in situ denitrification in groundwater

M.W. Killingstad·M.A. Widdowson·R. L. Smith
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Abstract

A two-dimensional numerical solute transport model was developed for simulating an enhanced in situ denitrification experiment performed in a nitrate-contaminated aquifer on Cape Cod, Massachusetts. In this experiment, formate ( HCOO - ) "> (HCOO-) was injected for a period of 26 days into the carbon-limited aquifer to stimulate denitrification. Calibration of the vertical-profile site model was demonstrated through error analysis and comparison with formate, nitrate, and nitrite concentration data monitored along a transect of three multilevel groundwater sampling wells for 75 days after initial injection. Formate utilization rates were approximately 142 and 38 μM/day for nitrate and nitrite reduction, respectively. Nitrate and nitrite utilization rates were approximately 29 and 8 μM/day, respectively. Nitrate utilization rates under enhanced conditions were 1 order of magnitude greater than previously reported naturally occurring rates. The nitrite production rate was approximately 29 μM/day. Persistence of nitrite was attributed to a combination of factors, including electron donor (formate) limitation late in the experiment, preferential utilization of nitrate as an electron acceptor, and greater nitrite production relative to nitrite utilization.

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M.W. Killingstad, M.A. Widdowson, R. L. Smith. 2002. Modeling enhanced in situ denitrification in groundwater. https://doi.org/10.1061/(asce)0733-9372(2002)128%3A6(491)

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