|Johnson, Melvin - Mel|
|Reddy, G - North Carolina Agricultural And Technical State University|
Submitted to: International Conference on Wetland Systems for Water Pollution Control
Publication Type: Proceedings
Publication Acceptance Date: 11/1/2008
Publication Date: 11/1/2008
Citation: Ro, K.S., Hunt, P.G., Johnson, M.H., Matheny, T.A., Reddy, G.B. 2008. Oxygen transfer in marsh-pond-marsh constructed wetlands treating swine wastewater. In: Proceedings of the International Conference on Wetland Systems Technology in Water Pollution Control, November 1-7, 2008, Indore, India. p. 1143-1150.
Technical Abstract: Marsh-pond-marsh (M-P-M) constructed wetlands have been used to treat wastewater from swine anaerobic lagoons. To mitigate undesired ammonia emission from M-P-M, ponds were covered with floating wetlands (M-FB-M). The pond sections of the M-FB-M were covered with floating wetlands consisted of recycled rubber mat on which American bulrush (Schoenoplectus americanus) was planted. Ammonia emissions were measured using a wind tunnel; oxygen transfer efficiencies of the aerated ponds were estimated by conducting the American Society of Civil Engineers' standard oxygen transfer tests. Biochemical oxygen demand and total nitrogen loading and escaping rates from each wetlands were used to calculate carbonaceous and nitrogenous oxygen demands. Covering pond water surface with the floating bed slightly decreased oxygen transfer efficiency. The diffused membrane aeration (26.7 kg O2/ha/d) of M-P-M was surprisingly not as effective as plant aeration in marsh (38.9 to 42.0 O2/ha/d). This unusually low oxygen transfer efficiency of the diffused aeration was attributed to its low submergence depth of 0.8 m compared to typical depth of 4.5 m. The wetlands consisting entirely of marsh removed similar amounts of carbon and nitrogen without investing additional equipment and energy costs of aerating ponds in the middle of wetlands.