Numerical Modelling of Constructed Wetland using Software HYDRUS 2D

Abstract

One of the problems involving water bodies is the pollution of water sources, which later becomes the parent of various social, economic, and health problems. One of these conditions can be overcome by utilizing phytoremediation through constructed wetlands. HYDRUS is a software that offers easy modelling of pollutant decay mechanisms in water bodies and constructed wetlands using finite element method. This study aims to show and analyse how HYDRUS software can model the mechanism in constructed wetland by using finite element method. The parameters observed are the time for the pollutant, namely ammonia, nitrate, and inorganic phosphorous, to reach the outlet, and the response curve of the pollutant loading on the model. From the simulation, it can be inferred that the maximum velocity of the water going through the constructed wetland is 8.11 m/day, or 811 cm/day. The dominating velocity in the wetland is around 160 cm/day, or 1.6 m/day. The response curve of the pollutant transport is also in accordance with theoretical response for impulse loading. The result yields the effectivity of simulated constructed wetland, which are 90.33% for ammonia and nitrate, and 90.26% for inorganic phosphorous. The result yields quite optimistic effectivity of the constructed wetland, which may be caused by the assumptions made in the model, which goes through simplification method. It can also be caused by the differences in plants assumption. In the HYDRUS simulation, the plant used is grass, which does not specify what kind of grass. Meanwhile, the physical simulation uses water bamboo.