MODELING HEAVY METALS (CR, NI, PB) TRANSPORT IN SOIL UNDER SEWAGE SLUDGE APPLICATION

摘要

The purpose of this study is to assess the possiblerncontamination of the groundwater by heavy metalsrnderived from sewage sludge through a plot study. For thisrnpurpose, two experimental plots, each size 2 by 10 m atrnWastewater Treatment Plant-Shoush was prepared. A pvcrndrainage pipe was installed in one meter depth of eachrnplot to collect the leached water. The first plot wasrnirrigated with pipe water as control plot. The second onernwith sewage sludge from Shoush wastewater treatmentrnPlant where is located in the south of Tehran. Soilrnsamples were taken from the topsoil to 100 cm depth,rneach sample for every 10 cm depth from each plot. Cr, Nirnand Pb concentration was measured as a function of depthrnafter 150 days. Hydrus-1D was calibrated for heavyrnmetals transport in the site. Modeling and experimentalrnresults were nearly the same. Simulation results for plot 2rnindicated small risk of groundwater contamination.rnHowever high concentration of heavy metals near the soilrnsurface raises a concern about leaching as macropore andrnpreferential flow. Simulation results for plot 2 indicatesrnthat in Hydrus -1D adsorption parameters were estimatedrnin order to allow a deeper transport of heavy metalsrnwhich had actually occurred duo to macropore flow.