Wastewater treatment process of aluminum profile

by:Zeyi     2021-06-15
It is understood that environmental pollution problems have arisen to varying degrees across the world, including air pollution, marine pollution, and urban environmental pollution. As we all know, the production process of aluminum profile is also very polluting to our environment, so how to deal with aluminum profile wastewater? Let's talk about the process of aluminum profile wastewater treatment. 1. Wastewater characteristics of aluminum profile The aluminum profile production process mainly includes: degreasing, alkali etching, pickling, oxidation, sealing and coloring of the formed aluminum profile. The profile after the above-mentioned process needs to be cleaned with water. This part of the profile The cleaning water is discharged from the cleaning tank in the form of overflow, which is the main source of wastewater generated in the aluminum profile factory. In addition to a large amount of aluminum ions, the wastewater produced by aluminum profile manufacturers also contains some metal ions such as zinc, nickel, and copper. The pH of the wastewater varies depending on the production requirements, and the majority of them are acidic.  Second, the process flow of aluminum profile wastewater treatment  In view of the characteristics of aluminum profile wastewater that mainly contains various metal ions and suspended solids, the process of neutralization adjustment and coagulation sedimentation is adopted.   Aluminum profile production wastewater is discharged from the workshop and then flows into the neutralization and adjustment tank. The tank is equipped with air agitation to balance the water quality. After the wastewater is balanced in the water quality and volume of the adjustment tank, alkali is added to adjust the pH value to 6-9, and then pumped into the sedimentation tank, and the flocculant (PAM) is added at the same time during the pumping process. After the metal ions in the wastewater react with alkali to form hydroxides, under the action of the flocculant, they form larger particles of alum, which settle quickly under the action of gravity. The upper half of the sedimentation tank can be directly discharged to the outside. The quality of the effluent It has reached the second-level emission standard of the second-class area of u200bu200bGuangdong Province, DB 4426-89, the local emission standard.   The sludge in the sedimentation tank is concentrated in the sludge tank and pumped into the plate and frame filter press for dewatering and then used for sanitary landfill or comprehensive utilization.  3. Process principle of aluminum wastewater treatment  1. Regulating tank: In the aluminum wastewater treatment, the regulating tank is divided into two types: intermittent and continuous. During manual adjustment, the adjustment tank needs to be divided into two compartments. The residence time of the wastewater in each compartment is 1~2 h. It is used in turn and intermittently to facilitate manual adjustment; for automatic adjustment, only one compartment is required. pH value, due to the aluminum profile wastewater contains a large amount of aluminum, and aluminum is in an amphoteric state in the solution. When pH<3, the main form of aluminum is Al(H2O)3+6; when pHu003d7, aluminum hydroxide becomes the main form of Al3+; when pH>8.5, most of the aluminum hydroxide is hydrolyzed into bands Negatively charged complex anion. Therefore, the pH value must be controlled in an appropriate range during engineering commissioning so that aluminum can fully precipitate in the form of aluminum hydroxide.  2. Reaction tank: The main function of the reaction tank is to fully react Al3+ and OH- in the aluminum profile wastewater to form insoluble Al(OH)3 precipitation. Usually vertical flow sedimentation tanks use vortex flow reactors, and advection sedimentation tanks use baffled flow reactors. 3. Coagulation sedimentation tank: after the metal ions in the wastewater react with alkali in the adjustment tank, insoluble hydroxides are formed. However, due to the small particles formed, they are not easy to settle under the action of water flow, so flocculants must be added to make These particles adhere to each other and aggregate into larger particles, which are removed by solid-liquid separation in the sedimentation tank. The sedimentation tank adopts advection or vertical flow, especially the latter is the most widely used. Vertical flow sedimentation tank is particularly suitable for floc settlement, and is simple to operate, easy to manage, and the supernatant can be drained directly. The retention time of the sedimentation tank is 2h, and the surface load is 1m3/(m2•h).  
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