Copper-containing wastewater recovery method and device

Abstract

The invention relates to a method for recovering copper-containing wastewater. The method comprises the following steps: S1, collecting the copper-containing wastewater, adjusting the pH value, and settling; s2, after coarse filtration, filtering by using an ultrafiltration membrane system to obtain crude water; and S3, adjusting the pH value of the crude water, and desalting in a reverse osmosis membrane system to obtain discharge water. Compared with traditional MBR membrane treatment, through an ultrafiltration membrane system, especially a tubular membrane, the occupied area is reduced, and the civil engineering and dosing cost is reduced; the water quality requirement of the inlet pipe type membrane system is low, the inlet water pretreatment cost is reduced, and positive and back washing can be carried out; through cooperative application of parameters such as the membrane component material, the membrane aperture and the welding overlapping width of the membrane component, the service life of the membrane can be ensured, and meanwhile, the requirement of relatively high membrane treatment flux can be met.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, in particular to a method and device for recovering copper-containing wastewater. Background Art

[0002] Copper is a harmful heavy metal, both from the perspective of ecological safety and human health. Excessive intake of copper can cause severe mucosal irritation and corrosion, stomach discomfort and ulcers, liver and kidney damage, chronic copper poisoning and brain damage. For the semiconductor industry, its production and manufacturing process will produce a large amount of copper-containing wastewater. Some high-concentration copper-containing wastewater is generally treated by outsourcing. If low-concentration copper-containing wastewater is properly treated, it can be recycled and reused, which greatly saves water resources.

[0003] In the prior art, low-concentration copper-containing wastewater is mainly treated by adding heavy capture agents to capture copper ions in the sedimentation water, and then removing them by sedimentation. However, there are the following disadvantages: (1) The price of heavy capture agents is relatively high, and the use of heavy capture agents will greatly increase the cost of reagents; (2) When adding heavy capture agents, PAC, PAM and other reagents need to be added in combination, which increases the cost of reagents; (3) The traditional sedimentation method has a long process flow and high civil engineering investment costs. Summary of the invention

[0004] The object of the present invention is to provide a method and device for recovering copper-containing wastewater.

[0005] The technical solution to achieve the purpose of the present invention is:

[0006] A method for recovering copper-containing wastewater comprises the following steps:

[0007] S1, collect the copper-containing wastewater, adjust the pH value and settle it;

[0008] S2, after coarse filtration, use an ultrafiltration membrane system to filter to obtain crude water;

[0009] S3. After the pH value of the raw water is adjusted, it enters the reverse osmosis membrane system for desalination to obtain discharge water.

[0010] Furthermore, in step S1, the pH value of the added liquid alkali is adjusted to 7-9. The liquid alkali used can be a sodium hydroxide solution with a mass percentage of 10%-30%, and the copper ions in the wastewater are reacted to generate precipitation and then filtered and removed by an ultrafiltration membrane system.

[0011] Furthermore, in step S3, the pH value of the crude water is adjusted to 6.5-7.5 using an acidic solution, such as dilute sulfuric acid.

[0012] Furthermore, the ultrafiltration membrane system uses a tubular membrane made of polyvinylidene fluoride (PVDF). The tubular membrane system can be composed of 1 to 6 tubular membrane modules connected in parallel or in series. Each tubular membrane module contains 4 to 500 membrane tubes. The waste liquid flows through the membrane tube, and the permeate crude water flows into the outside of the membrane module after passing through the membrane filtration. Among them, the diameter of the membrane tube of the tubular membrane module is 6 to 13 mm, the length is 0.3 to 6 m, and the end face of the tubular membrane module is 2 to 10 inches. The tubular membrane module is fed with water, and the feed pressure is 0 to 0.8 MPa. The membrane tube tensile value of the tubular membrane module is above 400 N. The PVDF membrane tube is cross-welded by two layers of non-woven fabrics, the inner and outer layers, and the surface of the non-woven fabric is coated with PVDF casting liquid. Furthermore, the inner surface of the two layers of non-woven fabric is coated with PVDF casting liquid. The cross welding of the inner and outer layers of the PVDF membrane tube can be carried out by ultrasonic cross welding on a film rolling machine, and the welding overlap width is 1.8-2.0 mm. Preferably, the diameter of the membrane tube of the tubular membrane module is 8 mm and the length is 3-4 m.

[0013] The overlapping welding position of the PVDF membrane tube cannot filter wastewater, but the larger the welding overlap width, the higher the tensile strength of the membrane tube.

[0014] When the end face dimensions are the same, the diameter of the membrane tube is different, and the corresponding membrane surface area is different. The lower the diameter of the membrane tube, the larger the membrane surface area and the higher the water treatment volume, but the tensile strength value will be lower. The larger the diameter of the membrane tube, the lower the membrane surface area, but the higher the membrane tube tensile value.

[0015] The higher the tensile value of the membrane tube, the longer the service life of the membrane assembly. For example, if the tensile value of the membrane tube is above 400N, the membrane operating pressure is 0.35MPa, the operating time is 20h / d, and the membrane service life is 3-5 years.

[0016] Among them, the flow rate of copper-containing wastewater is 10-200t / h, the pH of copper-containing wastewater is 1-11, and Cu is 0-200mg / L.

[0017] Furthermore, the above copper-containing wastewater recovery method can be implemented using the following device:

[0018] It includes a pretreatment component, an ultrafiltration membrane system, a neutralization treatment component and a reverse osmosis system connected in sequence. The pretreatment component includes a wastewater collection tank, a PH adjustment tank, a reaction tank and an intermediate tank connected in sequence. The PH adjustment tank, the reaction tank and the intermediate tank are three-grid tanks, the PH adjustment tank is connected to the bottom of the reaction tank, and the overflow from the upper part of the reaction tank enters the intermediate tank.

[0019] The ultrafiltration membrane system is a tubular membrane, which is composed of 1 to 6 tubular membrane components connected in parallel or in series.

[0020] The neutralization treatment component includes a neutralization tank and an ultrafiltration water production tank connected in sequence. Sulfuric acid is added to the neutralization tank to adjust the pH and then flows into the ultrafiltration water production tank.

[0021] After copper-containing wastewater is collected, it enters the wastewater collection pool and is pumped into the pH adjustment pool. Liquid alkali with a concentration of 20% is added through the dosing pipe to adjust the pH to 7-9 to ensure that the copper ions are completely precipitated. The reacted wastewater enters the reaction pool through the connecting pipe at the bottom of the pH adjustment pool. After the reaction, the wastewater enters the intermediate pool through the overflow pipe at the top of the reaction pool. The wastewater in the intermediate pool is pumped into the tubular membrane system through a pump, and the membrane inlet pressure is 0-0.8MPa. The tubular membrane system produces water through a pipe and enters the neutralization pool. Dilute sulfuric acid is added to the neutralization pool to adjust the pH to 6.5-7.5. The water overflows from the neutralization pool and enters the ultrafiltration water production pool. The water in the ultrafiltration water production pool is pumped into the RO membrane system through the RO feed pump and enters the RO membrane system after being pressurized by the RO booster pump. The RO produced water can be used for pure water preparation.

[0022] Compared with the prior art, the present invention has the following significant advantages:

[0023] Compared with traditional MBR membrane treatment, the ultrafiltration membrane system, especially the tubular membrane, reduces the floor space, construction and chemical addition costs; the tubular membrane system has low water quality requirements, reduces the cost of water pretreatment, and can also perform forward and backwashing; through the coordinated use of parameters such as membrane component material, membrane pore size, and welding overlap width of the membrane component, it can not only ensure the service life of the membrane but also meet the requirements of higher membrane treatment flux. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0025] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0026] Example 1

[0027] Membrane tubes made of PVDF and PEK were selected respectively, with a membrane pore diameter of 8mm and a welding width of 2mm. 30cm of each tube was cut and placed on the test equipment. The test device consisted of a 2L circulation tank, a diaphragm pump, inlet and outlet pressure gauges, a circulation flow meter and pipelines. Pure water was added to the 2L circulation tank and pumped into the membrane tube by a diaphragm pump. The manual valve at the inlet of the membrane tube was fully opened. The opening of the manual valve at the outlet of the membrane tube of the test equipment was adjusted to adjust the inlet pressure to 0.15MPa and the outlet pressure to 0.10MPa. The produced water was collected every 5 minutes for 1 minute each time. The pure water flux of the membrane tube was calculated based on the water production in 1 minute. The average value of 30 minutes was taken as the average water production flux. The inlet and outlet pressures of the membrane tube needed to be adjusted to be consistent each time during the test. The results showed that the average pure water flux of the PVDF membrane tube was 800L / (m 2 h) and above, the average pure water flux of PEK material is 300L / (m 2 h) below.

[0028] Cut 20cm of each type of membrane tube and place it on a tensile testing machine to test its longitudinal tensile value. Randomly take 5 batches of PVDF material membrane tubes, the tensile values ​​are 430, 451, 445, 460, 442N / (mm) respectively. 2 , the tensile values ​​of PEK film tubes are 401, 395, 412, 435, 420 N / (mm) respectively 2 .

[0029] Example 2

[0030] The membrane flux and tensile value experiments described in Example 1 were conducted by taking PVDF membrane tubes with welding widths of 1.5 mm, 1.8 mm, 2.0 mm, 2.2 mm, and 2.5 mm, and membrane pore diameters of 8 mm, 30 cm, and 20 cm, respectively. See Table 1 for details.

[0031] Table 1

[0032]

[0033] Example 3

[0034] Take PVDF membrane tubes with a welding width of 2.0 mm to make membrane tubes with different membrane pore sizes, and test the membrane flux and tensile value of Example 1. See Table 2 for details.

[0035] Table 2

[0036]

[0037] Taking into account the anti-pollution performance of the membrane tube and the water production per unit area, a membrane pore diameter of 8 mm is preferably used as the pore diameter of the membrane tube of the membrane module mainly made of organic tubular membranes.

[0038] Example 4

[0039] The raw water flow of copper-containing wastewater in a semiconductor factory is 90t / h, PH4.71, COD30mg / L, Cu19.5mg / L, ammonia nitrogen 0.9mg / L, total phosphorus 2.1mg / L, total nitrogen 1mg / L; Figure 1 As shown, wastewater recovery is carried out according to the following device and method:

[0040] 1. The raw water is collected and enters the wastewater recycling tank, and then pumped into the pH regulating tank. Liquid alkali with a concentration of 20% is added through the dosing pipe for online monitoring, and the pH is adjusted to 8-9 until the copper ions are completely precipitated. The wastewater after the alkali reaction enters the reaction tank through the bottom connecting pipe of the pH regulating tank, and after the reaction, the wastewater enters the intermediate tank through the overflow pipe on the upper part of the reaction tank;

[0041] 2. The wastewater in the intermediate pool is pumped into the tubular membrane system (membrane tube diameter 8mm, overlap width 2mm) through the ultrafiltration system feed pump. After entering the tubular membrane system, the wastewater is pumped into the tubular membrane through the high-pressure circulation pump. Three sets of tubular membrane systems are connected in parallel, and each system has 6 tubular membranes with an end face of 8 inches and a length of 3m, and the membrane material is PVDF. The membrane pore diameter is 30nm, the membrane inlet pressure of a single system is 0.35MPa, the circulation flow rate is 120t / h, the membrane outlet pressure is 0.10MPa, the membrane water flow rate is 30t / h, the operation time is 20h / d, the operation flexibility is 50-110%, the membrane water turbidity is 0.17NTU, SS<1mg / L, and the water production is connected to the pipeline to enter the neutralization tank;

[0042] 3. The produced water is connected through a pipeline to the neutralization tank, and dilute sulfuric acid is added to adjust the pH to 6.5-7.5. The feed pump is used to automatically backwash the system every 40 minutes. The water overflows from the neutralization tank and enters the ultrafiltration water production tank. The water in the ultrafiltration water production tank is pumped into the RO membrane system through the RO feed pump, and then enters the RO membrane system after being pressurized by the RO booster pump. The discharge water is obtained after RO filtration.

[0043] Example 5

[0044] The raw water flow of copper-containing wastewater in a semiconductor factory is 100t / h, PH7.71, COD35mg / L, Cu25.1mg / L, ammonia nitrogen 1.1mg / L, total phosphorus 2.5mg / L, total nitrogen 1.5mg / L; the wastewater is recovered according to the following device and method:

[0045] 1. The raw water is collected and enters the wastewater recycling tank, and then pumped into the pH regulating tank. Liquid alkali with a concentration of 20% is added through the dosing pipe for online monitoring, and the pH is adjusted to 8-9 until the copper ions are completely precipitated. The wastewater after the alkali reaction enters the reaction tank through the bottom connecting pipe of the pH regulating tank, and after the reaction, the wastewater enters the intermediate tank through the overflow pipe on the upper part of the reaction tank;

[0046] 2. The wastewater in the intermediate pool is pumped into the tubular membrane system through the ultrafiltration system feed pump. After entering the tubular membrane system, the wastewater is pumped into the tubular membrane system through the high-pressure circulation pump. It is composed of 4 tubular membranes (diameter of membrane tube is 8mm, overlap width is 2mm) with 10-inch end face and 3m long PVDF membrane material in series; the membrane pore size is 30nm, the system membrane inlet pressure is 0.50MPa, the circulation flow rate is 260t / h, the membrane outlet pressure is 0.10MPa, the membrane water production flow rate is 100t / h, the operation time is 20h / d, the operation flexibility is 50-110%, the membrane water production turbidity is 0.13NTU, SS<1mg / L;

[0047] 3. The produced water is connected to the pipeline and enters the neutralization tank. Dilute sulfuric acid is added to adjust the pH to 6.5-7.5. A high-level recoil tank is connected 1m above the top of the produced water side. The system is backwashed through the high-level recoil tank every 40 minutes. The water overflows from the neutralization tank and enters the ultrafiltration water production tank. The water in the ultrafiltration water production tank is pumped into the RO membrane system through the RO feed pump, and enters the RO membrane system after being pressurized by the RO booster pump. The discharge water is obtained after RO filtration.

[0048] In Example 4 and Example 5, the service life of the membrane is shown in Table 3:

[0049] Table 3

[0050]

Claims

1. A method for recovering copper-containing wastewater, characterized in that: The method comprises the following steps: S1, collect the copper-containing wastewater, adjust the pH value and settle it; S2, after coarse filtration, use an ultrafiltration membrane system to filter to obtain crude water; S3, after adjusting the pH value of crude water, it enters the reverse osmosis membrane system for desalination to obtain discharge water; The ultrafiltration membrane system uses a tubular membrane, which is composed of 1 to 6 tubular membrane modules connected in parallel or in series.

2. The method for recovering copper-containing wastewater according to claim 1, characterized in that: The tubular membrane is selected from polyvinylidene fluoride, and each tubular membrane module contains 4-500 membrane tubes; the diameter of the membrane tube of the tubular membrane module is 6-13mm, the length is 0.3-6m, and the end face of the tubular membrane module is 2-10 inches; the tensile value of the membrane tube of the tubular membrane module is above 400N.

3. The method for recovering copper-containing wastewater according to claim 2, characterized in that: The membrane tube is made of two layers of non-woven fabrics, inner and outer layers, which are cross-welded. PVDF casting liquid is coated on the surface of the non-woven fabrics, and the welding overlap width is 1.8-2.0 mm.

4. The method for recovering copper-containing wastewater according to claim 3, characterized in that: The diameter of the membrane tube of the tubular membrane module is 8mm and the length is 3-4m.

5. The method for recovering copper-containing wastewater according to claim 1, characterized in that: The flow rate of copper-containing wastewater is 10-200t / h, the pH of copper-containing wastewater is 1-11, and Cu is 0-200mg / L.

6. The method for recovering copper-containing wastewater according to claim 1, characterized in that: In step S1, the pH value of the added liquid alkali is adjusted to 7-9; in step S3, the pH value of the crude water is adjusted to 6.5-7.

5.

7. A device for recovering copper-containing wastewater, characterized in that: The device comprises a pretreatment component, an ultrafiltration membrane system, a neutralization treatment component and a reverse osmosis system connected in sequence; the pretreatment component comprises a wastewater collection tank, a PH adjustment tank, a reaction tank and an intermediate tank connected in sequence; the PH adjustment tank, the reaction tank and the intermediate tank; The ultrafiltration membrane system is a tubular membrane, which is composed of 1 to 6 tubular membrane modules connected in parallel or in series. The neutralization treatment component includes a neutralization tank and an ultrafiltration water production tank which are connected in sequence; sulfuric acid is added to the neutralization tank to adjust the pH and then flows into the ultrafiltration water production tank.

8. The device for recovering copper-containing wastewater according to claim 7, characterized in that: The tubular membrane is selected from polyvinylidene fluoride, and each tubular membrane module contains 4-500 membrane tubes; the diameter of the membrane tube of the tubular membrane module is 6-13mm, the length is 0.3-6m, and the end face of the tubular membrane module is 2-10 inches; the tensile value of the membrane tube of the tubular membrane module is above 400N.

9. The device for recovering copper-containing wastewater according to claim 8, characterized in that: The membrane tube is made of two layers of non-woven fabrics, inner and outer layers, which are cross-welded. PVDF casting liquid is coated on the surface of the non-woven fabrics, and the welding overlap width is 1.8-2.0 mm.

10. The device for recovering copper-containing wastewater according to claim 9, characterized in that: The pH regulating tank, reaction tank and middle tank are three-compartment tanks. The pH regulating tank is connected to the bottom of the reaction tank, and the overflow from the upper part of the reaction tank enters the middle tank.

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