Efficiency of Different Isfahan Unites of Water Treatment Plant in Removal of Heavy Metals

Surface waters contain different pollutants such as heavy metals. When raw water that contains these metallic ions flows into the water treatment plant, the conventional water treatment processes are unable to remove them. Removal efficiency and variations in the concentration of these ions depend on the operating conditions of water treatment plant. In this study, the removal percentage of heavy metals such as iron, manganese, copper and nickel were measured in different stages of water treatment processes as in Isfahan Water Treatment Plant. Samples were taken from influent, before and after sedimentation and also after filtration under standard conditions. Concentrations of heavy metals in each sample were measured by atomic absorption spectrophotometry. The results revealed that the range of heavy metals concentrations in the influent for iron, manganese, copper and nickel were between 0.0-1.14, 0.0-0.0473, 0.0-0.817 and 0.012-0.107mg/l respectively. It was also found that concentrations of Fe, Mn, Cu and Ni in effluent were 0.0-0.373, 0.0-0.032, 0.0-0.120 and 0-0.175 respectively. Sedimentation was found the most efficient unit in removal of Mn, Cu and Ni. It was also found that filtration is the most efficient unit in removal of iron. The results showed that under critical conditions application of specific water treatment process is required in order to eliminate unacceptable heavy metals concentrations.