Method for treating waste water after workpiece tinplating

Abstract

This invention relates to a treatment method of waste water, in particular to a treatment method of waste water discharged after tinned workpieces. The treatment method is as follows: limewater is added into acidic waste water ready for treatment to adjust the acidic waste water into neutral waste water; soluble calcium chloride is added to the obtained mixture of neutral waste water and the sediments to ensure that the residual sulfate ion combines with the calcium ion to generate slightly soluble calcium sulfate deposition; the obtained mixture of waste water and the sediment is discharged to a stage I sedimentation tank, and a coagulant, a heavy metal ion collector and a flocculant are added in sequence to accelerate the gathering of copper hydroxide sediments, tin hydroxide sediments and calcium sulfate sediments so as to enlarge the volume of various sediments and separate the waste water and the sediments; the obtained mixture of waste water and the sediments are discharged into a stage II sedimentation tank from the water discharged from the stage I sedimentation tank so as to further separate the water and the sediments. The invention can ensure the sulfate ion in the tinning waste water reach the discharge standard and lower the treatment cost at the same time.

Description

Technical field [0001] The invention relates to a waste water treatment method, in particular to a waste water treatment method after a workpiece is tin-plated. Background technique [0002] The wastewater after tin plating of the workpiece is mainly acidic, and contains a large amount of free copper ions, tin ions, and sulfate ions, which cause serious damage to the soil and water sources and is called one of the three polluting industries. Therefore, it is necessary to The pH value of wastewater drops to between 6-9, the copper ion is controlled below 1mg / L, and the sulfate content is lower than 600mg / L before it can be discharged. At present, there are three main ways to treat electroplating wastewater. First, the wastewater treatment process in the electroplating plant is to add alkali to the wastewater and directly discharge it after neutralization. Although this treatment method can effectively control the pH in the wastewater, it is difficult to control the sulfate in the ...

AI Technical Summary

Problems solved by technology

First, the wastewater treatment process of the electroplating plant is to add alkali to the wastewater and then discharge it directly. Although this treatment method can effectively control the pH in the wastewater, it is difficult to control the sulfate radicals in the discharged wastewater, and it is difficult to achieve Second, membrane separation technology or ion exchange method, but the engineering installations of this kind of sewage treatment are complicated, the infrastructure investment and engineering construction are long, and the cost of treating one ton of sewage needs 10-15 yuan, plus other chemicals, the total chemicals The fee is more than 15 yuan, resulting in high cost of sewage treatment

Third, the pH and sulfate content are reduced by adding groundwater to the wastewater. This method not only wastes a lot of water resources, but also is difficult to control the sulfate content and cannot meet the discharge standards.

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