The objective of this study was to determine concentrations of heavy metals leaving seven municipal wastewater treatment plants (MWWTPs), and reaching streams and rivers environment. Five metals including Cd, Pb, Cu, Zn and Cr, ranging from 0.01 to 0.27 mg/l and 0.17 to 225.83 mg/kg dw were detected in water and sediments, respectively. Industries and institutions wastewater were found to be the most important source for heavy metals in wastewater treatment plants (WWTPs). Concentrations of Pb, Cd and Cr in water were found to be higher than the maximum permissible limits as per Tanzania Bureau of Standard. High concentration in sediments beyond maximum limits for sediment quality guidelines (SQG) were detected for Pb, Zn and Cu. The results indicate that MWWTPs contribute to heavy metal pollution to Dar es Salaam environment. Acute health consequences in the investigated areas can be insignificant, but chronic adverse health effects due to prolonged pollution and long term exposure through vegetables consumption, washings, animal keeping and fishing can be inevitable.
Environment, heavy metals, municipal wastewater, water, sediment
