Treatment system and treatment process for printed circuit board wastewater

Abstract

The invention relates to the technical field of water treatment, and particularly discloses a treatment system and a treatment process for printed circuit board wastewater. The printed circuit board wastewater treatment system comprises a production wastewater feeding pool, a pretreatment unit, an MCR tank, a concentrated water treatment unit and a reuse water pool which are sequentially connected through ports. The pretreatment unit comprises a pH regulating tank, a decomplexing adsorption section and a precipitation section which are sequentially connected through ports, and a composite adsorbent is put into the decomplexing adsorption section. The treatment system for the printed circuit board wastewater can be used for recycling the printed circuit board wastewater, and has the advantages that the operation is simple and convenient, and complex-state heavy metal ions in the wastewater can be efficiently removed.

Description

Technical Field

[0001] The present application relates to the field of water treatment technology, and more specifically, to a printed circuit board wastewater treatment system and treatment process. Background Art

[0002] The printed circuit board industry has expanded dramatically over the past decade due to the rapid growth in market demand for electronic and electrical devices. The current printed circuit board industry involves various toxic chemicals in different manufacturing processes, such as circuit board preparation, circuit pattern transfer, etching and electroplating processes. These processes pose serious potential hazards to the environment and human health. In particular, during the etching step, about 70% of copper is removed from copper-clad printed circuit boards and waste etchants with high concentrations of copper ions are generated. 1m 3 The amount of waste etchant produced in printed circuit board production is between 1.5 and 3.5 L, and the total annual waste etchant production worldwide is about 1 billion m 3 .

[0003] Compared with free heavy metal ions, complex heavy metals are highly water-soluble, can exist stably in a wide pH range and have complex forms, which increases the diffusion performance of heavy metals in environments such as groundwater, and are therefore easily absorbed by organisms and organisms. Generally, the potential toxicity of complex heavy metals is higher than that of individual organic ligands and free heavy metals, and they are difficult to remove. Traditional chemical precipitation methods are difficult to achieve satisfactory treatment results, and the effluent cannot meet emission standards. If not handled properly, once it enters the food chain, it will accumulate in the human body at high concentrations, leading to serious health risks. Therefore, the treatment of complex heavy metal wastewater has become one of the urgent issues to be addressed in environmental protection.

[0004] At present, the treatment methods for printed circuit board wastewater include chemical precipitation, ion exchange, membrane separation, etc. With respect to the above-mentioned related technologies, the inventors found that simple chemical precipitation, ion exchange and membrane separation methods not only have complex process flows and high operating costs, but also have poor removal effects on complexed copper, nickel and tin, and it is difficult to stably achieve a high wastewater reuse rate, and the reused water is difficult to meet the water quality standards of tap water (conductivity ≤ 200μs / cm). Summary of the invention

[0005] In order to improve the removal effect of complex heavy metal ions in printed circuit board wastewater, the present application provides a printed circuit board wastewater treatment system and treatment process.

[0006] In the first aspect, the present application provides a printed circuit board wastewater treatment system, which adopts the following technical solution: a printed circuit board wastewater treatment system, comprising a production wastewater input pool, a pretreatment unit, an MCR tank, a concentrated water treatment unit and a reuse water pool whose ports are connected in sequence.

[0007] By adopting the above technical solution and setting up multiple units such as pretreatment units, MCR tanks, and concentrated water treatment, multi-level integration of wastewater treatment can be achieved, treatment efficiency can be improved, and effective classification treatment and resource recovery can be achieved for the complex pollutant components in PCB wastewater, which is in line with the current trend of environmental protection and sustainable development.

[0008] Optionally, the pretreatment unit includes three input ends, and the output end of the production wastewater input tank is connected to the first input end of the pretreatment unit; The MCR tank includes two output ends, the first output end is connected to the input end of the concentrated water treatment unit, and the second output end is connected to the sludge tank; The sludge tank comprises two output ends, the first output end is connected to a plate-and-frame filter press, and the second output end is connected to the second output end of the pretreatment unit; The plate and frame filter press comprises two output ends, the first output end outputs the dry sludge, and the second output end is connected to the third input end of the pretreatment unit.

[0009] By adopting the above technical solution, the flexibility and processing capacity of the pretreatment unit are enhanced by setting three input ends. The setting of the sludge pool not only realizes the centralized treatment of sludge, but also forms a closed-loop treatment process through the connection of the second output end with the pretreatment unit, improves the recycling rate of wastewater treatment, improves the overall treatment efficiency of the system, and through the circulation design, it also helps to reduce the use of chemicals, reduce the operating cost of the system, and improve the resource utilization rate of sludge.

[0010] Optionally, the MCR tank includes an MCR membrane, a water production self-priming pump and an instrument valve, and the MCR membrane flux is 12-15 L / m 2 ·h, the filter pore size is 0.4μm.

[0011] By adopting the above technical solution and through precise parameter setting, the processing accuracy and stability of the MCR tank are improved, the service life of the equipment is extended, and the maintenance cost of long-term operation is reduced.

[0012] Optionally, the pretreatment unit includes a pH adjustment tank, a decomplexation adsorption section, and a precipitation section, the ports of which are sequentially connected.

[0013] By adopting the above technical solution, the complexes and suspended solids in the wastewater can be effectively removed through steps such as pH adjustment, decomplexation adsorption and precipitation. In particular, for the heavy metal ions in the complex state, decomplexation treatment is performed first and then precipitation is performed in the pretreatment stage, which can significantly reduce the content of complex heavy metal ions in the wastewater. This step-by-step treatment method improves the pretreatment efficiency, reduces the load of subsequent treatment units, and provides good water quality conditions for subsequent MCR treatment and reverse osmosis treatment.

[0014] Optionally, the concentrated water treatment unit includes a pH correction tank, a primary reverse osmosis unit and a secondary reverse osmosis unit, the ports of which are connected in sequence, and the primary reverse osmosis unit and the secondary reverse osmosis unit both include a reverse osmosis membrane, a water inlet pump, a high-pressure pump and an instrument valve.

[0015] By adopting the above technical solution and using two-stage reverse osmosis in series, deep removal of metal ions in wastewater is achieved. The application of this multi-stage reverse osmosis technology significantly improves the system's desalination rate and metal ion removal efficiency, greatly reduces the dissolved solids content in wastewater, improves the water quality of produced water, and maximizes the utilization of wastewater resources.

[0016] Optionally, the primary reverse osmosis unit includes two output ends, a first output end is connected to an input end of the secondary reverse osmosis unit, and a second output end is connected to an input end of a reuse water pool; The secondary reverse osmosis unit includes two output ends, the first output end outputs concentrated water, and the second output end is connected to the input end of the reuse water pool. The reverse osmosis membrane flux in the primary reverse osmosis unit and the secondary reverse osmosis unit is 12-15L / m 2 ·h, desalination rate ≥97%.

[0017] In a second aspect, the present application provides a printed circuit board wastewater treatment process, which adopts the following technical solution: A printed circuit board wastewater treatment process comprises the following steps: S1: The wastewater enters the pretreatment unit from the production wastewater input pool and stays there for 12-16 hours, the pH is adjusted to 8-9, and a composite adsorbent is added for decomplexation adsorption and precipitation. The amount of composite adsorbent added is 40-60% of the mass of the wastewater treated in a single time by the pretreatment unit; S2: The produced water after precipitation enters the MCR tank and stays there for 1-3 hours. Under the action of the MCR membrane, large particle flocs are filtered, so that pollutants such as large particle flocs are trapped in the MCR tank to achieve solid-liquid separation; S3: The water produced by the MCR tank enters the concentrated water treatment unit, and the pH value of the wastewater is adjusted to 6-7. The unabsorbed metal ions such as nickel, tin, and copper in the wastewater pumped into the concentrated water treatment unit are further intercepted by the reverse osmosis membranes of the primary reverse osmosis unit and the secondary reverse osmosis unit, and the produced water passes through the reverse osmosis membrane into the reuse water pool.

[0018] By adopting the above technical scheme, the treatment process of the present application has the advantages of simple process, low cost, good removal effect, low energy consumption, etc., and has good promotion and application prospects in the field of wastewater deep treatment technology.

[0019] Optionally, the raw materials of the composite adsorbent include, by weight, 10-30 parts of chitosan fibers, 1-5 parts of crown ether compounds, 10-20 parts of foam plastics, and 0.1-0.5 parts of titanate coupling agents.

[0020] By adopting the above technical scheme, the skeleton structure of the foam plastic has a large number of pores and a complex network structure, forming a multi-level pore system of micropores and macropores. These pores not only increase the specific surface area of ​​the foam plastic, but can also be used as a carrier to load the adsorbent, providing more active sites for the adsorbent, increasing its chance of contact with complexed heavy metals; they also provide more channels for heavy metal ions to enter the interior of the material, which is beneficial to the diffusion and adsorption of heavy metal ions.

[0021] Crown ether compounds, due to their unique ring structure, can more accurately identify and adsorb complexed heavy metal ions. Chitosan fiber has a high specific surface area and porosity, providing a large number of adsorption sites. After being compounded with crown ether compounds, it can significantly increase the adsorption capacity for heavy metal ions, while also improving the mechanical strength and stability of the composite adsorbent and improving the durability of the composite adsorbent.

[0022] In addition, chitosan has good hydrophilicity and can swell in water to form gel, which helps to improve the contact and adsorption of heavy metal ions in aqueous solution. The chemical selectivity of crown ether compounds combined with the physical adsorption of chitosan microspheres can achieve more efficient heavy metal ion capture. Titanate coupling agents can react chemically with amino or hydroxyl groups in chitosan fibers to form a chemical cross-linking network, promote the gelation of chitosan fibers, and improve the chemical stability and structural strength of the composite adsorbent.

[0023] Optionally, the crown ether compound is dibenzo-18-crown-6.

[0024] By adopting the above technical scheme, compared with the separation of other complexed heavy metal ions, since copper ions can form more stable complexes with a variety of complexing agents, the solubility and stability of copper ions in aqueous solution are increased, making it difficult to precipitate or remove by conventional methods. The use of dibenzo-18-crown-6 utilizes the single selectivity and high adsorption of crown ether polymers for metal ions, and loading it in foam plastics can effectively adsorb and separate complexed copper ions.

[0025] Optionally, the method for preparing the composite adsorbent comprises the following steps: S1: Mix chitosan fiber and dibenzo-18-crown-6 evenly, mix with ethanol at a solid-liquid ratio of 1:(5-9), continue to add titanate coupling agent, and stir evenly to form a mixed solution; S2: The mixed solution is evenly coated on the foam plastic substrate and cured.

[0026] By adopting the above technical solution, the preparation method of the composite adsorbent of the present application is simple and easy to promote in industry.

[0027] In summary, this application has the following beneficial effects: 1. In the pretreatment unit of the wastewater treatment system of the present application, the complexed heavy metals are separated and removed in a targeted manner by setting up a decomplexation adsorption section and a precipitation section, which can effectively improve the removal effect of complexed heavy metal ions in printed circuit board wastewater and provide good water quality conditions for subsequent MCR treatment and reverse osmosis treatment.

[0028] 2. In the present application, foam plastic is used as a carrier skeleton, and a complex of crown ether compounds and chitosan fibers is loaded on the foam plastic to prepare a composite adsorbent, forming a complex porous hierarchical system inside, which provides more active sites for the composite adsorbent and effectively improves the selectivity and adsorption of the composite adsorbent for complexed heavy metal ions.

[0029] 3. The method of the present application can realize multi-level integration of wastewater treatment, improve treatment efficiency, and achieve effective classification treatment and resource recovery for the complex pollutant components in PCB wastewater, which is in line with the current trend of environmental protection and sustainable development. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a functional module diagram of the printed circuit board wastewater treatment system of the present application.

[0031] Figure 2 It is the functional module diagram of the preprocessing unit.

[0032] Figure 3 It is the functional module diagram of the concentrated water treatment unit. DETAILED DESCRIPTION

[0033] The present application is further described in detail below in conjunction with all the accompanying drawings.

[0034] The present application provides a printed circuit board wastewater treatment system for recycling the printed circuit board wastewater.

[0035] like Figure 1 As shown, a printed circuit board wastewater treatment system of the present application includes a production wastewater input pool, a pretreatment unit, an MCR tank, a concentrated water treatment unit and a reuse water pool, the ports of which are connected in sequence.

[0036] The pretreatment unit includes three input ends, and the output end of the production wastewater input tank is connected to the first input end of the pretreatment unit. The pretreatment unit includes a pH adjustment tank, a decomplexing adsorption section and a precipitation section, the output end of the precipitation section is connected to the input end of the MCR tank. The production wastewater is adjusted to alkaline pH in the pH adjustment tank, adsorbent is added to the decomplexing adsorption section, alkali is added to the precipitation section, and the complexed heavy metal ions in the production wastewater are removed. After solid-liquid separation, it enters the MCR tank to complete the pretreatment process.

[0037] The MCR tank includes two output ends, the first output end is connected to the input end of the concentrated water treatment unit, and the second output end is connected to the sludge tank. The sludge tank includes two output ends, the first output end is connected to the plate and frame filter press, and the second output end is connected to the second input end of the pretreatment unit. The MCR tank also includes an MCR membrane, a water production self-priming pump and an instrument valve. The MCR membrane flux is 12-15L / m 2 ·h, the filter pore size is 0.4μm.

[0038] The plate and frame filter press comprises two output ends, the first output end outputs the dry sludge separated in the sludge tank for external transportation, and the second output end is connected to the third input end of the pretreatment unit.

[0039] After being filtered in the MCR tank, the pollutant sludge such as large particle flocs that are trapped is collected in the sludge pool for preliminary mud and water treatment and separation, and the produced water enters the pretreatment unit again for recycling treatment. The sludge enters the plate and frame filter press for filtration, and the solid-liquid separation is carried out under the action of the filter press to form produced water and dry sludge, and the produced water enters the pretreatment unit for recycling treatment.

[0040] The concentrated water treatment unit includes a pH correction tank, a primary reverse osmosis unit and a secondary reverse osmosis unit, the ports of which are connected in sequence. The primary reverse osmosis unit and the secondary reverse osmosis unit both include a reverse osmosis membrane, a water inlet pump, a high-pressure pump and an instrument valve. The primary reverse osmosis unit and the secondary reverse osmosis unit both include two output ends. The first output end of the primary reverse osmosis unit is connected to the input end of the secondary reverse osmosis unit, and the second output end is connected to the input end of the reuse water tank. The first output end of the secondary reverse osmosis unit discharges concentrated water, and the second output end is connected to the input end of the reuse water tank.

[0041] The reverse osmosis membrane flux in the primary reverse osmosis unit and the secondary reverse osmosis unit is 12-15L / m 2 ·h, desalination rate ≥97%.

[0042] The produced water in the MCR tank enters the concentrated water treatment unit, passes through the primary reverse osmosis unit, and enters the reuse water pool. The concentrated water enters the secondary reverse osmosis unit for recycling again. The secondary recovered produced water enters the reuse water pool, and the concentrated water is transported out for treatment.

[0043] raw material Unless otherwise specified, the raw materials used in the preparation examples, application examples and comparative examples in this application are all commercially available products, specifically: The foam plastic is polyurethane foam plastic, selected from Huaxin Insulation Material Factory, Dongyaotou, Dacheng County, 2022, and cut into cubes weighing 1-10g; Chitosan fiber, selected from Qingdao Hailan Biological Products Co., Ltd., 38DD; Dibenzo-18-crown-6, selected from Jiangsu Pulex Biotechnology Co., Ltd., 14187-32-7; Titanate coupling agent, selected from Dongguan Shanyi Plastic Co., Ltd., titanate coupling agent 201.

[0044] Preparation example of composite adsorbent Preparation Example 1 The composite adsorbent, various raw materials and the amount of each raw material are shown in Table 1, wherein the crown ether compound is dibenzo-18-crown-6.

[0045] Table 1 Preparation Example 1 Preparation Example 2 Preparation Example 3 Preparation Example 4 Chitosan fiber / Kg 25 10 30 20 Crown ether compounds / Kg 5 2 4 1 Foam plastic / Kg 14 10 20 17 Titanate coupling agent / Kg 0.2 0.1 0.5 0.2 The preparation method of the composite adsorbent comprises the following steps: S1: mixing chitosan fiber and crown ether compound uniformly, mixing with ethanol at a solid-liquid ratio of 1:9, adding titanate coupling agent, and stirring uniformly to form a mixed solution; S2: The mixed solution is evenly coated on the foam plastic substrate and cured.

[0046] Preparation Example 2 The composite adsorbent is different from Preparation Example 1 in that the raw materials and the amounts of the raw materials are as shown in Table 1, and the preparation method thereof comprises the following steps: S1: mixing chitosan fiber and crown ether compound uniformly, mixing with ethanol at a solid-liquid ratio of 1:5, adding titanate coupling agent, and stirring uniformly to form a mixed solution; S2: The mixed solution is evenly coated on the foam plastic substrate and cured.

[0047] Preparation Example 3 The composite adsorbent is different from Preparation Example 1 in that the raw materials and the amounts of the raw materials are as shown in Table 1, and the preparation method thereof comprises the following steps: S1: mixing chitosan fiber and crown ether compound uniformly, mixing with ethanol at a solid-liquid ratio of 1:7, adding titanate coupling agent, and stirring uniformly to form a mixed solution; S2: The mixed solution is evenly coated on the foam plastic substrate and cured.

[0048] Preparation Example 4 The composite adsorbent is different from Preparation Example 1 in that the raw materials and the amounts of the raw materials are shown in Table 1, and the other steps are the same as Preparation Example 1.

[0049] Preparation Example 5 The composite adsorbent is different from Preparation Example 1 in that no crown ether compound is used, and the crown ether compound in the raw material is replaced by an equal mass of chitosan fiber.

[0050] Preparation Example 6 The composite adsorbent is different from that in Preparation Example 1 in that chitosan fiber is not used, and the chitosan fiber in the raw material is replaced by an equal mass of crown ether compounds.

[0051] Application Examples The present invention discloses a printed circuit board wastewater treatment process, which is carried out using a printed circuit board wastewater treatment system of the present invention, wherein the composite adsorbent used is prepared by Preparation Examples 1-6. Application Example 1 A process for treating printed circuit board wastewater, wherein the composite adsorbent is prepared by Preparation Example 1, comprising the following steps: S1: The wastewater enters the pretreatment unit from the production wastewater input pool and stays there for 14 hours. NaOH is added to the pH adjustment tank to adjust the pH to 8-9. A composite adsorbent is added to the decomplexation adsorption section for decomplexation adsorption. Excessive NaOH is added to the precipitation section to precipitate metal ions. The amount of composite adsorbent added is 60% of the mass of wastewater treated in the pretreatment unit in a single treatment. S2: The produced water after sedimentation enters the MCR tank and stays there for 2 hours. Under the action of the MCR membrane, large flocs are filtered, so that large flocs and other sludge are retained in the MCR tank to achieve solid-liquid separation. The sludge enters the sludge pool for further separation and treatment, and the produced water enters the pretreatment unit for recycling and treatment. The remaining sludge enters the plate and frame filter press for filtration, and solid-liquid separation is performed again. The liquid enters the pretreatment unit for recycling and treatment, and the dry sludge is transported out; S3: The water produced by the MCR tank enters the concentrated water treatment unit, and H2SO4 with a concentration of 40% is added to the pH adjustment tank to adjust the pH of the wastewater to 6-7. The unadsorbed metal ions such as nickel, tin, and copper in the wastewater pumped into the concentrated water treatment unit are further intercepted by the reverse osmosis membranes of the primary reverse osmosis unit and the secondary reverse osmosis unit. The water produced by the primary reverse osmosis unit and the secondary reverse osmosis unit passes through the reverse osmosis membrane and enters the reuse water tank.

[0052] Application Example 2 A process for treating printed circuit board wastewater, wherein the composite adsorbent is prepared by Preparation Example 2, comprises the following steps: S1: The wastewater enters the pretreatment unit from the production wastewater input pool and stays there for 12 hours. NaOH is added to the pH adjustment tank to adjust the pH to 8-9. A composite adsorbent is added to the decomplexation adsorption section for decomplexation adsorption. Excessive NaOH is added to the precipitation section to precipitate metal ions. The amount of composite adsorbent added is 40% of the mass of wastewater treated in the pretreatment unit in a single treatment. S2: The produced water after sedimentation enters the MCR tank and stays there for 3 hours. Under the action of the MCR membrane, large flocs are filtered, so that large flocs and other sludge are retained in the MCR tank to achieve solid-liquid separation. The sludge enters the sludge pool for further separation and treatment, and the produced water enters the pretreatment unit for recycling and treatment. The remaining sludge enters the plate and frame filter press for filtration, and solid-liquid separation is performed again. The liquid enters the pretreatment unit for recycling and treatment, and the dry sludge is transported out; S3: The water produced by the MCR tank enters the concentrated water treatment unit, and H2SO4 with a concentration of 40% is added to the pH adjustment tank to adjust the pH of the wastewater to 6-7. The unadsorbed metal ions such as nickel, tin, and copper in the wastewater pumped into the concentrated water treatment unit are further intercepted by the reverse osmosis membranes of the primary reverse osmosis unit and the secondary reverse osmosis unit. The water produced by the primary reverse osmosis unit and the secondary reverse osmosis unit passes through the reverse osmosis membrane and enters the reuse water tank.

[0053] Application Example 3 A process for treating printed circuit board wastewater, wherein the composite adsorbent is prepared by Preparation Example 3, comprises the following steps: S1: The wastewater enters the pretreatment unit from the production wastewater input pool and stays there for 16 hours. NaOH is added to the pH adjustment tank to adjust the pH to 8-9. A composite adsorbent is added to the decomplexation adsorption section for decomplexation adsorption. Excessive NaOH is added to the precipitation section to precipitate metal ions. The amount of composite adsorbent added is 50% of the mass of wastewater treated in a single treatment in the pretreatment unit. S2: The produced water after sedimentation enters the MCR tank and stays there for 1 hour. Under the action of the MCR membrane, large flocs are filtered, so that large flocs and other sludge are retained in the MCR tank to achieve solid-liquid separation. The sludge enters the sludge pool for further separation and treatment, and the produced water enters the pretreatment unit for recycling and treatment. The remaining sludge enters the plate and frame filter press for filtration, and solid-liquid separation is performed again. The liquid enters the pretreatment unit for recycling and treatment, and the dry sludge is transported out; S3: The water produced by the MCR tank enters the concentrated water treatment unit, and H2SO4 with a concentration of 40% is added to the pH adjustment tank to adjust the pH of the wastewater to 6-7. The unadsorbed metal ions such as nickel, tin, and copper in the wastewater pumped into the concentrated water treatment unit are further intercepted by the reverse osmosis membranes of the primary reverse osmosis unit and the secondary reverse osmosis unit. The water produced by the primary reverse osmosis unit and the secondary reverse osmosis unit passes through the reverse osmosis membrane and enters the reuse water tank.

[0054] Application Example 4 A treatment process for printed circuit board wastewater, which differs from Application Example 1 in that the composite adsorbent is prepared by Preparation Example 4, and the other steps are the same as those of Application Example 1.

[0055] Application Example 5 A treatment process for printed circuit board wastewater, which differs from Application Example 1 in that the composite adsorbent is prepared by Preparation Example 5, and the other steps are the same as those of Application Example 1.

[0056] Application Example 6 A treatment process for printed circuit board wastewater is different from Application Example 1 in that the composite adsorbent is prepared by Preparation Example 6, and the other steps are the same as those of Application Example 1.

[0057] Comparative Example Comparative Example 1 A treatment process for printed circuit board wastewater, which differs from Application Example 1 in that no composite adsorbent is added to the decomplexation adsorption section, and other steps are the same as those in Application Example 1.

[0058] Performance testing The various water quality indicators after recycling treatment of a printed circuit board wastewater treatment process of application examples 1-6 and comparative example 1 and the metal ion content before and after recycling treatment were tested. The specific detection method refers to GB3838-2002 "Surface Water Environmental Quality Standard". Each group of test water samples was tested 3 times, and the average value was recorded in Table 2.

[0059] Table 2 According to the performance test data results in Table 2, it can be seen that the printed circuit board wastewater treatment system of the present application can effectively remove various metal ions in the printed circuit board wastewater, and the various metal ion indicators after effluent meet the Class II emission standards of the "Surface Water Environmental Quality Standards".

[0060] According to the performance test results of Application Examples 1-4 and Comparative Example 1, the composite adsorbent used in the printed circuit board wastewater treatment process of the present application can effectively promote the adsorption of various complexed metal ions in the wastewater when applied to the decomplexation and adsorption section, significantly reduce the metal ion content in the recycled water, and improve the removal efficiency of the complexed metal ions.

[0061] According to the performance test results of Application Examples 1-4 and Application Examples 5-6, the composite adsorbent prepared with foam plastic as the skeleton structure has a significant effect on the removal of complexed metal ions in wastewater treatment. The physical adsorption of chitosan microspheres combined with the chemical selectivity of crown ether compounds can achieve more efficient capture of complexed heavy metal ions. Compared with the single use of foam plastic coating, the combined use of the two can form a more complex chemical cross-linking network, increase the adsorption capacity of the composite adsorbent for heavy metal ions, and improve the efficiency of wastewater treatment.

[0062] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A printed circuit board wastewater treatment system, characterized in that: It includes a production wastewater input pool, a pretreatment unit, an MCR tank, a concentrated water treatment unit and a reuse water pool, the ports of which are connected in sequence.

2. The printed circuit board wastewater treatment system according to claim 1, characterized in that: The pretreatment unit comprises three input ends, and the output end of the production wastewater input tank is connected to the first input end of the pretreatment unit; The MCR tank includes two output ends, the first output end is connected to the input end of the concentrated water treatment unit, and the second output end is connected to the sludge tank; The sludge tank comprises two output ends, the first output end is connected to a plate-and-frame filter press, and the second output end is connected to the second output end of the pretreatment unit; The plate and frame filter press comprises two output ends, the first output end outputs the dry sludge, and the second output end is connected to the third input end of the pretreatment unit.

3. The printed circuit board wastewater treatment system according to claim 2, characterized in that: The MCR tank includes an MCR membrane, a water production self-priming pump and an instrument valve. The MCR membrane flux is 12-15 L / m 2 ·h, the filter pore size is 0.4μm.

4. The printed circuit board wastewater treatment system according to claim 1, characterized in that: The pretreatment unit comprises a pH adjustment tank, a decomplexation adsorption section, and a precipitation section, the ports of which are sequentially connected.

5. The printed circuit board wastewater treatment system according to claim 1, characterized in that: The concentrated water treatment unit comprises a pH correction tank, a primary reverse osmosis unit and a secondary reverse osmosis unit, the ports of which are connected in sequence. The primary reverse osmosis unit and the secondary reverse osmosis unit both comprise a reverse osmosis membrane, a water inlet pump, a high-pressure pump and an instrument valve.

6. The printed circuit board wastewater treatment system according to claim 5, characterized in that: The primary reverse osmosis unit includes two output ends, a first output end is connected to an input end of the secondary reverse osmosis unit, and a second output end is connected to an input end of a reuse water pool; The secondary reverse osmosis unit includes two output ends, the first output end outputs concentrated water, and the second output end is connected to the input end of the reuse water pool. The reverse osmosis membrane flux in the primary reverse osmosis unit and the secondary reverse osmosis unit is 12-15L / m 2 h, desalination rate ≥97%.

7. A printed circuit board wastewater treatment process, characterized in that: The printed circuit board wastewater treatment system according to any one of claims 1 to 6 is used, comprising the following steps: S1: The wastewater enters the pretreatment unit from the production wastewater input pool and stays there for 12-16 hours, the pH is adjusted to 8-9, and the composite adsorbent is added for decomplexation adsorption and precipitation. The amount of composite adsorbent added is 40-60% of the mass of the wastewater treated in the pretreatment unit in a single time; S2: The produced water after sedimentation enters the MCR tank and stays there for 1-3 hours. Under the action of the MCR membrane, large particle flocs are filtered, so that large particle flocs and other pollutants are trapped in the MCR tank to achieve solid-liquid separation; S3: The water produced by the MCR tank enters the concentrated water treatment unit, and the pH value of the wastewater is adjusted to 6-7. The unabsorbed metal ions such as nickel, tin, and copper in the wastewater pumped into the concentrated water treatment unit are further intercepted by the reverse osmosis membranes of the primary reverse osmosis unit and the secondary reverse osmosis unit, and the produced water passes through the reverse osmosis membrane into the reuse water pool.

8. The printed circuit board wastewater treatment system according to claim 7, characterized in that: In parts by weight, the raw materials of the composite adsorbent include 10-30 parts of chitosan fiber, 1-5 parts of crown ether compound, 10-20 parts of foam plastic, and 0.1-0.5 parts of titanate coupling agent.

9. The printed circuit board wastewater treatment process according to claim 8, characterized in that: The crown ether compound is dibenzo-18-crown-6.

10. The printed circuit board wastewater treatment process according to claim 9, characterized in that: The preparation method of the composite adsorbent comprises the following steps: S1: Mix chitosan fiber and dibenzo-18-crown-6 evenly, mix with ethanol at a solid-liquid ratio of 1:(5-9), continue to add titanate coupling agent, and stir evenly to form a mixed solution; S2: The mixed solution is evenly coated on the foam plastic substrate and cured.

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