Hydrodynamics of horizontal subsurface flow constructed wetlands

Constructed wetland hydrodynamics were modeled using mathematical tools generally employed in chemical engineering processes. The hydraulic residence time (HRT) distributions of the subsurface horizontal flow constructed wetland from Curienne (France) were estimated using the impulsion tracer method. A non-ideal flow wetland was first modeled by classical method: the dispersion plug flow model (DPFM), which gives a constant ratio to axial dispersion (the Peclet number Pe), and the stirred tanks in series model (STSM), which gives a number of stirred tank in series (NSTS). Six experimental HRTs were monitored to determine flow characteristics. Several periods were monitored to represent different seasons. It was found that evapotranspiration played a major role in summer by improving HRT.