Modeling Cadmium Transport in Soil under Sewage Sludge Application

The purpose of this study is to assess the possible contamination of the groundwater by Cd derived from sewage sludge through a plot study.For this purpose, three experimental plots, each size 2 by 10 m at Wastewater Treatment Plant-Shoush was prepared. A pvc drainage pipe was installed in one meter depth of each plot to collect the leached water. First plot was irrigated with effluent from Shoush wastewater treatment Plant, second plot with sludge and pipe water, third plot with sewage sludge and effluent. Soil samples were taken from the topsoil to 100 cm depth, each sample for every 10 cm depth from each plot. Cd concentration was measured as a function of depth after 150 days. Hydrus-1D was calibrated for Cd transport in the site. Modeling and measured results were nearly the same. Simulation results for plot 1 indicated small risk ofgroundwater contamination. However high concentration of Cd near the soil surface raises a concern about the crop Cd uptake. Simulation results for plot 2 and 3 indicates that in Hydrus -1D adsorption parameters were estimated in order to allow a deeper transport of Cd which had actually occurred duo to macropore flow.

Keywords:

Cadmium , Sewage sludge , Transport , Hydrus 1D ,