Anoxic treatment wetlands for denitrification

Anoxic subsurface flow (SSF) constructed wetlands were evaluated for denitrification using nitrified wastewater. The treatment wetlands utilized a readily available organic woodchip-media packing to create the anoxic conditions. After 2 years in operation, nitrate removal was found to be best described by first-order kinetics. Removal rate constants at 20 degrees C (k(20)) were determined to be 1.41-1.30d(-1), with temperature coefficients (theta) of 1.10 and 1.17, for planted and unplanted experimental woodchip-media SSF wetlands, respectively. First-order removal rate constants decreased as length of operation increased: however, a longer-term study is needed to establish the steady-state values. The hydraulic conductivity in the planted woodchip-media SSF wetlands, 0.13-0.15 m/s, was similar to that measured in an unplanted gravel-media SSF control system. (C) 2010 Elsevier B.V. All rights reserved.