|Venterea, Rodney - Rod|
|ROSER, MARTA - University Of Minnesota|
|CHRISTIANSON, LAURA - Freshwater Institute|
Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 11/18/2014
Publication Date: N/A
Technical Abstract: Denitrification bioreactors are a promising technology for mitigation of nitrate-nitrogen (NO3-N) losses in subsurface drainage water. Bioreactors are constructed with carbon substrates, typically wood chips, to provide a substrate for denitrifying microorganisms. Columns were packed with wood chips (WC), barley straw (BS), corn cobs (CC), corn stover (CS), and a combination of corn cobs followed by wood chips (CC-WC). A synthetic water solution (50 mg L-1 of NO3-N) was pumped through the columns at a 12-h hydraulic residence time. Bioreactors were operated at 16°C (experiment 1) and 1.7°C (experiment 2). At 16°C, NO3-N removal was greatest for the CC treatment (35 g N m-3 d-1), and least for WC (1.4 -5.6 g N m-3 d-1). The BS, CS and CC-WC materials were intermediate in NO3-N removal. At the lower temperature, the same trend was observed with respect to the relative NO3-N removal by the different materials, but the NO3-N removal rate was decreased by 3 - 5X in all treatments (< 10 g N m-3 d-1). The abundance of denitrifying bacteria was assessed by qPCR analysis of the nosZ gene. Gene abundance followed a similar trend as NO3-N removal with CC supporting 3.76 x 10E12 gene copies and WC supporting 2.18 x 10E8 copies g-1. Gene abundance was not reduced in the cold temperature experiment.