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- Title
Biogeochemical-Based Design for Treating Ammonia Using Constructed Wetland Systems.
- Authors
Beebe, Donald A.; Castle, James W.; Rodgers, John H.
- Abstract
Constructed wetlands have been used to treat contaminants, including ammonia and nitrate, with varying degrees of success; however, no study has been performed to evaluate ammonia treatment performance of a constructed wetland specifically designed to promote biogeochemical conditions controlling nitrification and denitrification. Therefore, this research aims to improve the design of treating ammonia using constructed wetlands by targeting biogeochemical conditions needed for nitrification and denitrification. A pilot-scale constructed wetland was designed and constructed to meet targeted ranges of dissolved oxygen concentration, hydrosoil redox potential, pH, alkalinity, and organic carbon availability to enhance nitrification and denitrification. Design features included aeration, sucrose, and oyster shell addition. The constructed wetland decreased ammonia-N from ∼20 mg/L in inflow to nondetectable levels (<0.1 mg/L) in outflow during three of the four treatment months. Measured biogeochemical conditions indicate that nitrification continued to occur while hydrosoil redox potential, dissolved oxygen concentration, and pH were lower than the targeted ranges. Conversely, denitrification continued to occur while pH was lower than the targeted range, and dissolved oxygen concentration was higher than the targeted range. The success of the constructed wetland in removing ammonia and nitrate under conditions outside of target ranges was attributed to the existence of heterogeneous macro- and microenvironments within individual wetland cells that allow both reactions to occur simultaneously under a wider range of conditions than previously expected. Results from this study demonstrated the advantage of designing constructed wetlands to promote biogeochemical conditions for improved ammonia treatment and also provide the basis for treatment of ammonia-contaminated produced waters.
- Subjects
AMMONIA; WETLANDS; NITRIFICATION; OIL field brines; WASTE treatment
- Publication
Environmental Engineering Science, 2015, Vol 32, Issue 5, p397
- ISSN
1092-8758
- Publication type
Article
- DOI
10.1089/ees.2014.0475