EVALUATION OF HEAVY METALS (Pb, Cu) POLLUTION IN LEACHING WATER FROM DISCHARGED SLUDGE OF KIM NGUU RIVER, HANOI

Abstract

Sewage sludge pollution discharged across two riverside of Kim Ngưu, Hanoi has been serious. When raining water (espcially acid rain) occurs, heavy metals accumulated in sludge are released, dissolving into water and then underground water. In this study, we investigate the mobilization of typical heavy metals, Pb and Cu, leached from Kim Nguu sewage sludge at different pH. At neutral pH (pH = 6.5), the dissolve of  Pb²⁺ và Cu²⁺ (Co = 0.11 và 0.11 mg/L equivalently) from sludge into water is slow and unstable, thus the concentrations of Pb and Cu in the water are low, namely that of Pb²⁺ và Cu²⁺ after 10 days determined are 14.73 và 15.11 mg/L equivalently. However, at acid pH (pH = 4.5), the transformation of Pb and Cu into water (espcially Pb) occurs fast, the concentrations of Pb²⁺ và Cu²⁺ increase sinificantly from 0.15 và 0.11 mg/L lên tới 26.20 and 18.76 mg/L equivalently. This result show that the risk of heavy metal pollution from sewage sludge of Kim Nguu river is high when occuring acid rain, the management and treatment of Kim Nguu river sludge is very important and neccesary to be implemented scientifically.