Heavy metals represent an important source of environmental pollution. Oil and petrochemical industries produce considerable amounts of heavy metals that finds its way to water sources such as rivers, lakes, sea, and ground water in addition to soil . Biological treatment units are unable to remove these metals since they are non-biodegradable. Considerable attention had been given for the treatment of heavy metals in recent years. North oil refineries company in Baiji suffer from the presence of many heavy metals in the discharged wastewater from biological treatment unit. The concentration of many of these heavy metals concentrations exceed the allowable concentrations according to the Iraqi limits. The present work is a trial to treat Copper, Manganeze, and Zinc from a synthetic wastewater using activated carbon. The study proved that these metals can be removed completely. However the breakthrough and exhaustion times for Zinc are lower than that of Copper and Manganese. The study proved also that adsorption capacity is not a pure property of activated carbon, but it depends on the operating conditions and the type of adsorbent and adsorbate and their characteristics.