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Oxygen Fluxes and Ammonia Removal Efficiencies in Constructed Treatment Wetlands
Author(s) -
Wu MeiYin,
Franz Eldon H.,
Chen Shulin
Publication year - 2001
Publication title -
water environment research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.356
H-Index - 73
eISSN - 1554-7531
pISSN - 1061-4303
DOI - 10.2175/106143001x143394
Subject(s) - oxygen , ammonia , wetland , constructed wetland , subsurface flow , environmental chemistry , chemistry , environmental engineering , typha , limiting oxygen concentration , nitrification , environmental science , hydrology (agriculture) , nitrogen , wastewater , ecology , groundwater , geology , biology , geotechnical engineering , organic chemistry
Ammonia‐removal efficiency in constructed wetlands is often limited by the amount of oxygen available in the system. In this study, the oxygen‐transfer rates to laboratory‐scale, subsurface‐flow and free‐water‐surface constructed wetlands were quantified for two input concentrations of ammonia, 10 and 50 mg nitrogen/L, both with and without Typha latifolia . Rates of oxygen diffusion into the subsurface‐flow constructed wetlands were 6.01 to 7.92 g/m 2 ·d and were strongly correlated with ammonia concentration in the water. In contrast, low oxygen diffusion rates of 1.36 to 1.76 g/m 2 ·d were observed for the free‐water‐surface system. The presence of Typha latifolia had small but consistent effects on atmospheric oxygen‐diffusion rates and ammonia‐removal efficiencies in both the subsurface‐flow and free‐water‐surface systems. The observed small effects were consistent with measurements of oxygen inputs from T. latifolia roots. Only approximately 0.023 g/m 2 ·d of oxygen was released from roots of T. latifolia , as measured using the titanium (III) citrate buffer method. The results for the ammonia‐removal rates of the laboratory‐scale constructed wetlands were further verified using pilot‐scale constructed wetlands under greenhouse conditions.