Comparative Modeling of HSF Constructed Wetland Performance with and Without Evapotranspiration and Rainfall

Abstract

The effects of meteorological parameters, i.e., evapotranspiration (ET) and rainfall (P), on the flow and BOD fate in horizontal subsurface flow constructed wetlands (HSF CW) are presented based on numerical simulation, using the Visual MODFLOW-MT3DMS code, which is based on the finite difference method. This model was used to simulate five HSF CW pilot-scale units, which were constructed and operated in the Laboratory of Ecological Engineering and Technology. Experimental data from these facilities were used to calibrate and verify the numerical procedure. ET was estimated based on a previous study proposing the use of the Blaney-Criddle method, and was introduced in the model. For a characteristic time period, rainfall values from observed events were also entered in the model. The model was then used to test effects of ET and rainfall on effluent concentration under various conditions, showing a more intense effect of ET and a less significant effect of rainfall. It was also used in test runs comparing the performance, without and with ET, under various vegetation, porous media size, HRT and temperature conditions.