Visiting Instructor, Civil & Environmental Engineering Manhattan College
Van Cortlandt Lake, an urban lake located in the Bronx, NY, has experienced high levels of eutrophication due to nutrient inputs from increased stormwater runoff, especially during wet weather events. Green infrastructure solutions are being explored to improve water quality in the lake to increase public access and recreation. One option being explored is denitrifying reactors using woodchips. These bioreactors have been studied for their use in treating agricultural runoff, but research showing their ability to treat stormwater in urban areas is limited. In this work, we evaluate the effectiveness of woodchip batch reactors and woodchip continuous flow reactors for denitrification. Additionally, we evaluate the effectiveness of these reactors under varying environmental conditions and with and without lime addition. Preliminary results for the batch reactor showed that nitrate, nitrite, and ammonia decreased over a 7 day period and then stabilized, suggesting an optimum exposure time for stormwater contact with woodchips for denitrification to occur. This work will be incorporated into green infrastructure plans which will utilize woodchip reactors and sinuosity to the channel downstream of the stormwater outfall to optimize exposure time. This work, and additional results for the continuous flow reactor, as well as the effect of other environmental conditions and lime to mitigate low pH levels will be presented.
