Aluminum Surface Treatment Wastewater Treatment Technology

[China Aluminum Industry Network] Introduction: Aluminum surface treatment with large amounts of water, resulting in more waste water, continuous discharge of harmful substances in wastewater. If not treated, it will pollute the environment. At the same time, China’s taxation on the amount of pollutants will also increase the cost and burden of enterprises. Therefore, considering the corporate social responsibility and benefits, wastewater treatment is necessary and necessary. The author summarizes the years of experience in process research and management of aluminum surface treatment and wastewater treatment, and proposes a practical and feasible wastewater treatment and reuse plan for peer reference. 1. The source and type of aluminum surface treatment wastewater: A: The aluminum surface treatment wastewater includes pre-treatment oil removal and after acidic water washing, alkali alkaline water after washing, acidic water washing after acid etching, acidic water washing after oxidation, and colored Ni2+. Sn2+, acid water wash water, waste acid generated from electrophoretic paint ion exchange device, waste alkali, and a small amount of electrophoretic paint wastewater. The wastewater is acidic after mixing and contains cations such as Al3+, Ni2+, Sn2+, Sn4+, Na+, Cr3+, and anions such as SO42-, F-, NO3-, Cl-, AlO2-, Ac-, surfactants and acrylic acid. Resins and other organic substances. The waste liquid contains waste sulfuric acid produced by degreasing and neutralization, waste sulfuric acid, waste sulfuric acid produced by oxidation, waste liquid produced by coloration, waste acrylic acid solution produced by electrophoretic paint, and waste liquid containing Ni2+, F-, etc. generated by sealing. 2. Measures to reduce the discharge of waste water and waste liquids: A: The measures for reducing waste water and waste liquids include reasonable control of water control time and control of loading angles to reduce the amount of bath liquid carried out, and use secondary three-stage countercurrent rinsing to reduce water consumption. After the etching and degreasing, the washed water is used for washing after alkali etching, and the washed water after oxidation is used for acid etching and washing after degreasing. In addition, in order to reduce or avoid the discharge of waste water and waste bath, various recovery devices should be designed and used in the production line, such as acid recovery, alkali recovery, anodization, aluminum RO, coloring RO recovery, electrophoretic coating RO Recovery devices that use these recovery devices can reduce the amount of waste water and waste liquid emissions to a large extent, while also greatly reducing the cost of production. 3, the principle and method of aluminum surface treatment wastewater treatment: Answer: The waste water produced by surface treatment of aluminum profiles is mainly acid-alkali waste water and contains a small amount of harmful anions and cations such as Ni2+, Sn2+, and F-. The treatment method is acid-base neutralization. Wastewater is generally acidic, and alkali must be added to neutralize the PH value to 7 ~ 8.5 or so. At the same time, in the neutralization process, cations such as Al3+, Ni2+, Sn2+, and Cr3+ form hydroxide precipitates. The neutralized and precipitated wastewater is pumped into the flocculation tank. At the same time, the dissolved polyamide flocculant is injected into the flocculation tank with a quantitative pump. After the flocculation, the wastewater enters the sedimentation tank. The sedimentation method includes inclined plate precipitation method and air flotation. Method, centrifugal precipitation, etc., I believe that the centrifugal precipitation method is relatively stable, after precipitation, the supernatant from the overflow overflow into the discharge tank or re-treatment reservoir. After the above-mentioned treatment of wastewater can be discharged, if you want to carry out wastewater reuse, this time the wastewater can be filtered into the RO device after treatment to remove excess anion and cations, organic matter, PH value may be low at this time , can be adjusted after the anion and cation exchange equipment to achieve reuse standards. The sludge produced by the sedimentation is periodically discharged into the sludge pool and processed into industrial waste residue after being processed by a plate-type cake pressing machine or a belt dehydrator and sent to the industrial waste residue treatment plant.