Enhancing Nutrient Retention Efficiency in Constructed Wetlands
Participants: Marc Horstman, François Birgand, Beth Allen
Timeline: August 2009 - May 2011
Funding: Dr. Birgand startup package
Project summary
Nitrogen dissipation in treatment wetlands receiving excess nitrate is limited in part by the ability of the nitrates to move from the water column to near the denitrifying microsites in the sediment. In stagnant water, the transport is of diffusive nature and therefore slow. Recent work has shown that advective transport from the water column into the sediment can be possible provided that water flows over porous obstacles. Adding advective transport of nitrate from the water column into the sediment could potentially largely enhance nitrogen treatment efficiency in constructed wetlands.
However, advective transport of nitrate in the sediment also implies an accompanying transport of oxygen. The latter being generally considered an inhibitor of denitrification, the benefit provided by advective transport might be offset by oxygen inhibition. Oxygen has also been found to enhance denitrification by stimulating the nitrification/denitrification processes. It was hypothesized that along advection exchange capacity gradient from low to high, nitrate dissipation would peak at an optimal point or range. This project aims at unveiling this optimal sediment/water exchange rate using a combined mesocosm and flume study.
This page was last updated on January 17, 2011.
