Up-to-standard discharge for low-concentration copper-containing wastewater in semiconductor industry and efficient sedimentation process thereof

Abstract

The invention relates to an up-to-standard discharge for low-concentration copper-containing wastewater in the semiconductor industry and an efficient sedimentation process. The process comprises thefollowing process steps: 1) adding a FeSO4 solution into the low-concentration copper-containing wastewater; 2) adding a calcium hydroxide solution into an inlet of a pipeline mixer at the bottom of an inclined plate sedimentation tank, and reacting the wastewater with calcium-containing modified sludge flowing back from the inclined plate sedimentation tank; 3) adding a recapturing agent for a chelating reaction; 4) adding polyacrylamide to carry out a flocculation reaction; and (5) introducing the sludge in the inclined plate sedimentation tank for mud-water separation, wherein one part of the sludge is conveyed to a sludge storage tank, the other part of the sludge is conveyed to a pipeline mixer, and performing the step (2). The method has the advantages that the FeSO4-recapturing agent combination is adopted according to wastewater characteristics, the use amount is reduced, the process is simple, the investment cost is low, coagulant adding and calcium hydroxide adding of returned sludge are omitted, the water content is low, the density is high, sludge sedimentation is accelerated, the surface load of the inclined plate sedimentation tank is increased, the occupied area is reduced, and a sludge concentration tank does not need to be arranged.

Description

technical field [0001] The invention relates to a treatment process for the low-concentration copper-containing wastewater produced in the semiconductor industry to meet the standard discharge and high-efficiency sedimentation, and belongs to the technical field of wastewater treatment. Background technique [0002] Various wastewaters are produced in the semiconductor manufacturing process, including copper-containing wastewater with a large proportion of water. At present, high-concentration copper-containing waste liquid is generally treated by outsourcing treatment, and low-concentration copper-containing waste water is discharged into the waste water treatment system for treatment. The pollutants in copper-containing wastewater mainly include hydrogen peroxide, copper ions and complexed copper. The content of complexed copper is as high as 70%, and it is difficult to precipitate complexed copper by adding alkali. [0003] In the prior art, copper-containing wastewater ...

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Problems solved by technology

[0003] In the prior art, copper-containing wastewater is mainly broken by ozone catalytic oxidation, Fenton oxidation, and adding heavy catcher, but there are the following disadvantages: (1) When using ozone technology to treat copper-containing wastewater, the utilization rate of ozone is low, resulting in The amount of ozone added is too large, and the investment cost is expensive; (2) When the Fenton process is used to treat low-concentration copper-containing wastewater, the amount of iron salt added is large, and the amount of sludge generated is large. It has a certain removal efficiency for complexed copper, but there are The risk of effluent not up to standard; (3) When heavy catchers are used for chemical precipitation, because of the high price of chemicals, using heavy catchers alone will greatly increase the cost of chemicals; (4) The moisture content of copper-containing sludge produced after physical and chemical treatment is extremely high, reaching More than 99%, the volume of copper-containing sludge is relatively large, the cost of sludge disposal and the investment cost of sludge thickening tank are relatively high

The problems of this process are: (1) The filler will be lost under acidic conditions and needs to be replenished regularly; (2) The pH of the wastewater will rise after micro-electrolysis treatment. Since this process does not add sulfuric acid, hydrogen peroxide is easy to decompose, resulting in the efficiency of the Fenton reaction (3) If the turbidity of the effluent is high, the UV utilization rate is low and the operating cost is high

[0008] From the above content, it can be seen that the treatment process of the prior art has the following problems: when using physical and chemical methods to treat low-concentration copper-containing wastewater in the semiconductor industry, in order to make the copper ions discharge up to the standard, the dosage of the chemical agent is large and the cost of the chemical agent is increased; NaHSO is usually used 3 Or alkali adjustment to remove hydrogen peroxide, but the removal efficiency of hydrogen peroxide is not high; due to the high water content of the sludge, the sludge volume is large, which increases the cost of sludge treatment; the surface load of the sedimentation tank is low, and the floor area is large, etc. question

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