Emetrgency Conttol Program Of Typical Divalent Heavy Metal Pollution In Source Water

This subject simulated that the source water was polluted by the Nickel (Ni), lead (Pb), cadmium (Cd),and the effects of removal of the three heavy metals by conventional coagulation - precipitation process on the source of the water were studied. Temperature, turbidity, coagulant type and dosage, pH may affect the removal of three heavy metals,and the author compared the differences. Meanwhile, the removal efficiency of heavy metals by potassium permanganate and powdered activated carbon in the coagulation - precipitation process was studied. When the source water was polluted by different times exceeded heavy metals or kinds of heavy metals, the optimal removal conditions were discussed.Existing conventional water coagulation - precipitation process had effect on removal of nickel, lead, cadmium three kinds of heavy metal. But they could not meet the standards. The temperature of source water had no significant effect to the removal of heavy metals .When the dosage of PAC, PFS and PAFC reached 80,80,90 mg/L or more, the removal of heavy metals had little difference at low temperature and room temperature. And the turbidity almost had no effect to the removal for heavy metals.Comprehensive comparing the removal of nickel, lead, cadmium under different dosage of PAC, PFS, PAFC, the author found that the removal was the best in the dosage of PAC 90mg/ L, without secondary pollution. But the water after treatment could not meet the standards.Improving the initial pH in thereaction could significantly improve the removal of heavy metals. when the initial pH during the reaction time was increased to 9.9,8.1,10.2,the source water polluted by nickel, lead, cadmium could meet the standards after treatment.KMnO₄ and powdered activated carbon had a certain effect for the removal of heavy metals. The removal effect using KMnO₄ or powdered activated carbon alone were already better than the conventional coagulation - precipitation process .And the combination of KMnO₄ and powdered activated carbon could obtain significant effect: the dosage of KMnO₄ and powdered activated carbon were 0.3 mg/L,20 mg/L and pH was 9.0; the dosage of KMnO₄ and powdered activated carbon were 0.3 mg/L,10 mg/L and pH was 7.5; the dosage of KMnO₄ and powdered activated carbon were 0.5mg/L, 20mg/L and pH was 9.3. The above conditions were the best coagulation conditions which could make 5 times standard limit of the heavy metal meet the standards.Under these three conditions the polluted water by three heavy metals could meet the standards after treatment. The above coagulation conditions were the best of enhanced coagulation conditions in this subject.The slight increase of the pH of the water source and KMnO₄ dosage could make the water that high exceeding and combined polluted by various heavy metals to meet the effluent standards by the optimal coagulation condition above.