Water Resources Research Act Program

Details for Project ID 2018NC221B

Improving performance and examining expansion of constructed wetlands for tertiary treatment of nitrogen from domestic and municipal wastewater

Institute: North Carolina
Year Established: 2018 Start Date: 2018-06-01 End Date: 2019-02-28
Total Federal Funds: $15,000 Total Non-Federal Funds: $45,000

Principal Investigators: Michael Burchell, Tarek Aziz, Francois Birgand

Abstract: Nitrogen (N) loading to our streams and rivers has improved since the mid-1990s through management practices that have focused on pollution from advanced wastewater treatment plants, urban stormwater, and agricultural facilities. However, load reductions to surface waters like the Neuse River have not reached targeted goals and eutrophication remains a major concern, particularly in the face of projected population increases and shifts in precipitation patterns that will only increase N pollution. A strategic shift in focus to smaller wastewater treatment systems in rural communities offers another solution for reducing N pollution. Often overlooked, the discharge limits for smaller systems for ammonia-nitrogen (NH4-N) are often high (10 mg/L) or even non-existent. Facilities that use aerobic processes to treat wastewater in smaller, rural communities often successfully treat NH4-N to low levels through the process of nitrification, but the effluent contains the byproduct nitrate-nitrogen (NO3-N) which in-turn also contributes to eutrophication. Installation of constructed wetlands, known for high N removal potential, placed strategically in the landscape to intercept water from smaller rural wastewater treatment facilities, could be a solution to help North Carolina get closer to its N reduction goals. These systems have been successful in NC; however, few are in operation, performance data are limited, and some older systems are showing signs of decreased N removal. The objectives of this research and outreach project are to study and improve N removal performance of an older existing constructed wetlands in Walnut Cove, NC and evaluate and demonstrate the impact constructed wetlands could have on overall watershed N reduction when used as tertiary treatment for smaller wastewater package plants.