Mathematical modeling of heavy metals contamination from municipality landfill site Khonkaen

Abstract

Kham Bon landfill site is one of many unsanitary municipality waste disposal sites in Thailand. The site has been receiving municipality and industrial wastes since 1968. Heavy metals were reported found in landfill leachate including Pb, Cr, and Cd. The main objective of this research is to study the contamination of heavy metals in soil and water using mathematical modeling. The existing condition of heavy metals contamination was investigated by measuring Pb, Cd, Cr in surface water, groundwater and soil in 2000 meter radius around the site. Contamination of such heavy metals in the environmental receptors was resulted as the pollutant migrated with runoff and subsurface aquifer at least 2 meters in depth and 500 meters radius surrounds the site. Contamination of Pb (0.50-5.00 mg/kg), Cr (2.00-5.00 mg/kg), and Cd (0-0.25 mg/kg) were found. However, heavy metals concentration in soil samples did not exceed the Pollution control Department (PCD) recommended standard for agriculture. In addition, Heavy metal concentration in surface water and groundwater did not exceed the Thai drinking water quality standard recommended by PCD. Contamination transport modeling was performed using Visual MODFLOW 3.1. Model results showed that heavy metals especially Pb and Cr migrated to the northeastern and southeastern part more than other parts due to the geological and flow network drain from the site northward and eastward to the surface water sources. 20 years prediction showed that, heavy metals tends to move from the top soil to deeper aquifer. The migration will not exceeded 500 m after 20 years and considered a slow process. It is recommended that hazardous waste sorting and ground water contamination in deeper aquifer should be closely monitored. In additional, the consumption of groundwater in 500 m radius should be avoided because it was contaminated with high level of heavy metals. During rainy season, the material to cover the waste from leachign with runoff should be applied. In the future, rehabilitation of the landfill site should be undertaken to prevent further mobilization of pollutants