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The goal of this study was to determine the removal efficiencies of chromium, copper, lead, nickel, and zinc from raw wastewater by chemically enhanced primary treatment (CEPT) and to attain a total suspended solids removal goal of 80%. Operating parameters and chemical doses were optimized by bench-scale tests. Locally obtained raw wastewater samples were spiked with heavy metal solutions to obtain representative concentrations of metals in wastewater. Jar tests were conducted to compare the metals removal efficiencies of the chemical treatment options using ferric chloride, alum, and anionic polymer. The results obtained were compared with those from other studies. It was concluded that CEPT using ferric chloride and anionic polymer is more effective than CEPT using alum for metals removal. The CEPT dosing of 40 mg/L ferric chloride and 0.5 mg/L polymer enhanced heavy metals removal efficiencies by over 200% for chromium, copper, zinc, and nickel and 475% for lead, compared with traditional primary treatment. Efficient metals capture during CEPT can result in increased allowable headworks loadings or lower metal levels in the outfall. Water Environ. Res., 80, 472 (2008). IntroductionThe presence of heavy metals in the influent to municipal wastewater treatment plants can adversely affect the performance of biological treatment processes and quality of the effluent and influence decisions regarding the reuse and land application of biosolids. These negative effects can result in limits on the allowable headworks metals loadings. Preventing heavy metals from reaching downstream processes and the receiving waters can be accomplished by removing the heavy metals using chemically enhanced primary treatment (CEPT) and can result in increased allowable headworks metals loadings or lower metal levels in the outfall.Chemical precipitation by coagulation and flocculation by trivalent metal salts is a century old and proven technology.