Fleming, M. S. University of California, Berkeley, mfleming@newton.berkeley.edu
Hume, N. S. University of California, Berkeley, noah@ce.berkeley.edu
Horne, A. J. University of California, Berkeley, horne@ce.berkeley.edu

 
THE EFFECT OF DOC ON NITROGEN REMOVAL KINETICS IN CONSTRUCTED WETLANDS: DENITRIFICATION AS A SECOND ORDER PROCESS
 
We carried out a flow-through microcosm experiment to test the effect of nitrate concentration and DOC on denitrification kinetics. Microbial denitrification is the principal removal mechanism for nitrogen in constructed wetlands, with available plant material (e.g., bulrush, cattail) as the primary source of reduced carbon (electron donor) for denitrifiers. However, little is known about the relationship between DOC from plant carbon and rates of nitrogen removal in wetlands. In past studies denitrification has been modeled as: 1) a process which is independent of nitrate concentration (zero order kinetics) and, 2) a process which is dependent on nitrate concentration (first order kinetics). We show that denitrification rates follow first order kinetics with nitrate within a plant species (r2=0.99), however the rate constants vary across species (k1=0.09-0.26 d-1). The rate constants are also positively correlated (r2=0.64) with DOC, suggesting that denitrification kinetics are dependent not only on nitrate concentration but also on DOC. Thus, we report an overall second order rate constant of 0.014 m2 mg-1 d-1 (p<0.005), which includes the additional effect of DOC on denitrification kinetics.
 
Day: Friday, Feb. 5
Time: 09:15 - 09:30am
Location: Sweeney Center
 
Code: CS55FR0915S