Evaluation of removal and fate of heavy metals in wastewater treatment plants

Heavy metals are important water pollutants since they have toxicity even at low doses and they are resistant to biodegradation. These metals, particulary in large cities, are found in wastewaters originated from residential areas and organized industrial zones and finally reached to municipal wastewater treatment plants for treatment. Municipal wastewater treatment plants are principally designed for organic pollutants removal, consist of treatment processes which are not suitable for heavy metal treatment. Therefore, effluents from municipal wastewater treatment plants threat receving water bodies and besides effluent stream, also, sludge is produced in these plants. Depending on final application, for example agricultural use, heavy metals concentrated in these sludges may lead problems. For these reasons, it is important to determine the amount, distribution and fate of the metals from the point of aquatic ecosystem and human health protection. The purpose of this study is to determine behaviors of heavy metals in wastewater treatment plants and to examine heavy metals removal efficiencies of existing treatment processes by monitoring liquid and solid phase heavy metals contents of municipal wastewater treatment plants. For this purpose, Hurma Wastewater Treatment Plant, which is the biggest treatment plant in Antalya, is selected. During one year every three months, composite wastewater samples from influent and effluent of the plant, grab wastewater samples from intermediate units and sludge samples were collected.These samples were digested by microwave and analysed for Cd, Hg, Pb, Ni, Cu, Zn, As, Cr metals by ICP-MS. Average yearly relative abundance of the metals in raw wastewater is As