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Nitrogen removal in a pilot-scale subsurface horizontal flow constructed wetland

Nitrogen removal in a pilot-scale submerged flow constructed wetland, planted with Phragmites australis and receiving domestic wastewaters was investigated for two years (November 1997-October 1999). Nitrification and denitrification simultaneously occurred in this system, showing the presence of both aerobic and anaerobic sites. A second-order polynomial regression fit well (R 2 = 0.9414) the experimental values of log K T versus T-20 in the temperature range 5-27°C. In addition, a linear trend (R 2 = 0.7834) could also be used as a first approximation in a narrower temperature range (10-27 °C); the rate constant at 20°C (K 20 ) for ammonium microbial oxidation was 0.3985 d -1 , which corresponds to a fully developed root zone.