Treatment And Reuse Process Study For Typical Metal Cleaning Wastewater

Aluminum foil and steel cleaning Wastewater were typical metal Wastewater, with large amounts of acid and metal ions. They would pollut the environment seriously if they discharge directly. Treatment and reuse with low power comsumption and high append value of the metal cleaning Wastewater was studied in this paper.Two processes for aluminum foil cleaning Wastewater treatment and reuse were researched in the present study. One was the separation and recycling of hydrochloric acid and aluminum sulfate, and the other was preparing PAC with aluminum foil cleaning Wastewater. The orthogonal experiment was designed in the first approach, results indicated that the concentration of the recovered hydrochloric acid was 6mol/L and the Cl^- was least on a condition that the vacuum, the ratio of the waste acid to the sulfuric acid and the concentration of aluminum were 0.075MPa, 250:11, and 1.5%, respectively. The technical design was finished based on the experimental results: the volume of reaction kettle was 2m³,the required temperature could be maitained by indirect heating with steam in 0.2MPa⁰.4MPa and the hydraulic suction was used to maintain a negative pressure 0.075 MPa in the reaction kettle.In the experiment of preparing PAC with aluminum foil cleaning Wastewater, the best ratio of Ca(AlO₂)₂ to aluminum foil cleaning Wastewater was 0.278 (g/ml). The alkalinity of the prepared PAC was 70.31%. The pH had effects to the alkalinity of the PAC, and the result showed that the higher pH the bigger alkalinity.In the treatment of oily Wastewater with PAC and aluminum sulfate which made from aluminum foil cleaning Wastewater, the flocculant dosage, pH and temperature influenced the flocculation effect. When the dosage of PAC was 0.6ml/L, pH 6～8, and the temperature was 20～40℃, it had the best flocculation effect on oily Wastewater, oil and the turbidity removal efficiency reached 69.46% and 92.28%, respectively. When the dosage of aluminum sulfate was 300mg/L in treatment of oily Wastewater, pH 5～8, the optimum temperature less...