Published in: 2010
Publisher:
PhD Thesis, Université de Liège Gembloux Agro-Bio Tech, Gembloux, Belgium
Author:
Fonder, N.
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The hydraulic and removal efficiencies of a Horizontal Flow Treatment Wetlands (HF TW) were
investigated through an internal three dimensional grid of sampling ports. Tracer tests and regular monitoring of water
quality parameters were performed. Results demonstrated that the HF TW has generally good hydraulic and volumetric
efficiencies, with relatively low dead zones. The application of models developed by chemical engineering provided the
number of tanks in series and the calculated detention times which were input as parameters in the multi flow with
dispersion hydraulic model. This second model identified that water fluxes were not homogeneous with depth inside the
TW and 60% of the flow was along the bottom layer of the bed. It also indicated the water flow velocities, which were
faster on the bottom of the bed, and the axial dispersion, which was higher where flow velocity was lower. The
reviewed inflow rate distribution allowed review for all layers of the nominal detention time and of the hydraulic
indexes, which are developed by the chemical engineering theory, and based on the incorrect assumption of
homogeneous systems. The P-k-C* degradation model was applied in order to define degradation k-rate values of BOD
and COD and the frequency distribution profiles were developed. The degradation rate coefficients for BOD ranked
from less than 10 m/yr to more than 300 m/yr. Significant higher degradation rates were observed for all the bottom
layers and for the closest sampling line from the inlet. The results of COD were similar to those observed for BOD.
Finally, the specific pollutants of nitrogen and phosphorus were analysed for total nitrogen (TN) and total phosphorus
(TP). The global trend of the TN degradation coefficient values was a slow and regular decrease over length, having
systematically higher degradation coefficients for the bottom layers. The saturation of the media sites for sorption
capacity of TP was demonstrated being in progress.
Fonder, N. (2010). Hydraulic and removal efficiencies of horizontal flow treatment wetlands. PhD Thesis, Université de Liège Gembloux Agro-Bio Tech, Gembloux, Belgium
Case studies in other formats Constructed wetlands English Europe & Central Asia
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