Dhaleshwari River Water Quality Due to Disposal of Tannery Wastes at Savar, Dhaka, Bangladesh

To assess the contamination load in Dhaleswari river water samples and its possible human health hazards, heavy metals concentration (Cr, Cd, Cu, Pb, Ni and Zn) in the study area were determined. The highest metal concentration was observed in main disposal point and the decreasing value was observed with the increasing distance in dry and wet season with significant differences among different sampling spots and in most of the cases metal concentration in water crossed the Maximum Permissible Limits (MPL). The DO (mg/L) in various sampling point were ranging from 0.08 to 7.82 and 0.08 to 6.76 mg L-1 and TDS from 209 to 7124 and 68.1 to 6,510 mg L-1 respectively, in dry and wet season. Chromium (Cr) concentrations in the Dhaleshwari river water and effluent samples were ranged from 0.0384 to 18,809.71 and 0.013 and to 37.68 mg L-1 respectively, in dry and wet season. Comparative higher values of heavy metals were found in dry season than wet season. Chromium (Cr) concentrations in river water and waste water/effluent samples at Savar sampling area were ranged from 0.0384 to 18,809.71 and 0.013 and to 37.68 mg L-1 respectively, in dry and wet season. Chromium concentrations in the water samples collected from Dhaleswari river in some sampling points, crossed the MAC (Maximum allowable concentration) at Savar study area for drinking (0.05 mg kg-1) (WHO 2004) [20] in dry season. Chromium (Cr) concentrations in waste water in dry and wet season were 18,809 and 37.68 mg L-1 and Pb concentrations at main disposal point of Savar tannery area crossed the standard value of effluents for inland surface water (0.1 mg L-1) (CPCB 1995) [4] respectively, which afflict the river water environment and thus lessen ecological balance.