Modeling of subsurface horizontal flow constructed wetlands using OpenFOAM®

Abstract

Natural purification of pollutants is one of the major ecosystem services provided by wetlands. The phenomenon of natural treatment is exploited by constructing artificial wetlands for the treatment of domestic wastewater. Various wetland models developed in the recent past range from simplistic regression analysis to highly complex deterministic systems. However, these models doesn’t suit to the moderate requirements of environmental practitioners for designing appropriate wetland systems. The present model simulates the dynamic behavior of sub-surface horizontal flow wetland systems by considering the non-linear hydrodynamics and pollutant transport, developed in an open source computational fluid dynamics environment—OpenFOAM®. The non-linear movement of wastewater in porous media is coupled with the advection-dispersion-decay multi-physics phenomenon of pollutant with temperature dependent rate kinetics. Sensitivity analysis of the model showed that, van Genuchten’s filter media shape parameters α, n, and decay constant λ influences the treatment efficiency of wetlands. Further, the model is useful in visualizing the spatio-temporal profiles of pollutants and hydrodynamics which eventually guide the environmental practitioners in better design of treatment wetland systems.