Soil Contamination and Environmental Risk Assessment from Relocated Tannery Industries in Savar, Dhaka, Bangladesh

The hazaribagh tanneries were relocated to Savar aimed to protect the heavily polluted Buriganga River from further contamination caused by unregulated industrial effluents. However, despite the relocation, the newly established Tannery Industrial Estate in Savar now discharges an estimated 12,000 to 15,000 cubic meters of untreated waste directly into the Dhaleshwari River each day. To evaluate the extent of soil contamination, concentrations of selected heavy metals—chromium (Cr), cadmium (Cd), copper (Cu), lead (Pb), nickel (Ni), and zinc (Zn)—were measured in the surrounding areas. Chromium (Cr), Cadmium (Cd), Copper (Cu), Lead (Pb), Nickl (Ni) and Zinc (Zn) concentration in soil samples at savar sampling area ranged from 51.20 to 9090.00 and 20.03 to 1635.00, 0.0 to 1.67 and 0.0 to 0.3, 3.40 to 54.36 and 8.28 to 50.62, 4.43 to 315.34 and 4.67 to 26.25, 7.47 to 59.33 and 14.94 to 90.12 and 7.47 to 59.33 and 14.94 to 90.12 mg kg-1, in dry and wet season, respectively. The highest metal conc. was observed in main disposal point and decreasing value was observed with increasing distance in dry and wet season with significant differences among different sampling spots and in most of the cases metal concentration in soil crossed the Maximum Permissible Limits (MPL) for soil. The Pollution Load Index (PLI) values of studied zone in dry season was 0.73 i.e nearest to 1.0 which confirmed that the soils are being polluted and will be deteriorated the quality of the zone if the present situation of discharging of wastes and effluents continues at newly relocated savar tannery area. The Central Effluent Treatment Plant (CETP) established at Savar frequently malfunctions, discharging untreated or partially treated tannery wastewater into the Dhaleshwari River. A major issue is the absence of a chrome recovery unit, resulting in the release of toxic chromium compounds. The government should enhance CETP performance by enforcing strict compliance, installing a chrome recovery unit, and ensuring regular monitoring through collaboration with academic and research institutions.