Experimental Study On Harmless Technology For Wastewater Treatment Of Aluminum Surface

The wastewater discharged by the aluminum alloy surface treatment contains varioussubstances, which is one kind of industrial wastewater with poor biochemical purificationability. The wastewater possesses complex components, with high concentration of thepollutants, high chroma, toxicity and stablity. The concentration of Cr(VI), F-and chromain the wastewater could not meet the national discharge standard, and the effluent wasorange with slight pungent smell and poor biochemical purification ability.In this paperthe simulated wastewater containing Cr(VI) was treated using the heavy metal chelatingagent and ferrite process, respectively. As for the fluoride removal, the chemicalprecipitation and coagulative precipitation were systematically studied.Two different methods for the treatment of the simulated wastewater containingCr(VI) were made a comparison. The results show that in the two methods, such factors aspH value, drug dosage, reaction time and temperature are significant. Heavy chelatingagent exhibits excellent removal efficiency under the following conditions: the time ofreaction is about50minutes, the quantity of chelating agents is14mL and pH value is1.0.The efficiency of the chelating agent capturing heavy metals ions is above99.98%. theexperiment on ferrite indicates that the removal efficiency is99.99%when thepharmaceutical dosage is2.57g, pH value of the oxidation-reduction reaction phase is2.7,pH value of the co-precipitation stage is9.0and the water temperature is70oC. The twotreatment methods can guarantee that the water quality satisfies the emission standards,and the optimum conditions are determined.The study of the two methods of fluoride removal in the wastewater suggests that asimple chemical precipitation is not efficient for the fluoride removal in wastewatertreatment, while the performance of chemical precipitation-coagulation for fluorideremoval is excellent. The combined method lime+PAC+PAM in fluoride removal issuperior to other methods. When the ratio of calcium and fluoride is2:1.1, PAC dosage is600mg/L, pH value is9.0and PAM dosage is3mg/L, the wastewater could come up tothe national discharge standard.