Complete device and method for efficiently recycling valuable substances in industrial wastewater step by step

Abstract

The invention provides a complete device and method for efficiently recycling valuable substances in industrial wastewater step by step. The device comprises a multi-chamber electrodialysis system, a high-power concentration system, a rectification extraction system and a cooling crystallization system. According to the multi-chamber electrodialysis system, under the action of an electric field, separation of valuable substances and organic substances is achieved by means of multiple layers of anion-cation exchange membranes, and a composite multi-walled carbon nanotube anion exchange membrane is adopted; the preparation method comprises the following steps: carrying out polymerization reaction on 2-acrylamido-2-methylpropanesulfonic acid, 1-butyl-3-vinyl-1H-imidazole-3-onium bromide and the multi-wall carbon nano tube. And the separated concentrated solution is subjected to high-power concentration, rectification extraction and cooling crystallization treatment, so that efficient step-by-step recovery of various valuable substances is realized. The separation process is simple and safe, the salt separation recovery rate is high, the separated and recovered salt can be reused in a production process section, the whole process is free of pollution discharge, industrial wastewater is promoted to be discharged to zero, and the method has remarkable environment-friendly and economic values.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, and in particular relates to a complete set of equipment and a method for efficiently and step-by-step recovery of valuable substances in industrial wastewater. Background Art

[0002] In recent years, with the increasing global climate change and environmental problems, industrial green transformation and the development of new ways of green low-carbon circulation have become important paths to achieve sustainable economic and social development and break through resource and environmental constraints. Industrial wastewater usually has the characteristics of high salt content, high organic matter concentration, high suspended solids content, high chroma, strong odor, high ammonia nitrogen concentration and high salt content.

[0003] At present, the mainstream treatment methods for industrial wastewater, such as physical, biological and chemical methods, mostly directly eliminate or remove substances in the wastewater, ignoring the existence of high-value substances in the wastewater, such as thiocyanate and acetate. Thiocyanate can be used to prepare thiocyanates, esters, various thiocyanides and cyanides, and is widely used in chemical, pharmaceutical and other industries, with great industrial value. Acetate is often used in the food industry as a food additive for sodium hydrogen acetate, with functions such as acidification and antiseptic. Acetate can also be used in the dye industry, pharmaceutical industry and other fields.

[0004] For the treatment of thiocyanate and acetate, industrial efforts are mainly focused on promoting recovery and reuse methods, or applying degradation technology to decompose thiocyanate in wastewater into harmless substances. Various methods and technologies are applied to the separation and recovery of thiocyanate, such as adsorption, photodegradation, membrane extraction, coagulation and precipitation, and advanced oxidation. However, there are problems such as high implementation costs and the generation of other pollutants, which lead to low purity of ions after separation and recovery, which greatly causes waste. Therefore, it is necessary to develop an efficient and low-cost treatment process to achieve the separation and recovery of valuable ions and realize resource utilization. Summary of the invention

[0005] The purpose of the present invention is to provide a complete set of equipment and method for efficiently recovering valuable substances in industrial wastewater in steps, which can separate and recover salt from pharmaceutical wastewater with high-value salt residues and reuse the salt in the production process.

[0006] The technical solution adopted by the present invention to achieve the above-mentioned purpose is: A complete set of equipment for efficient step-by-step recovery of valuable substances in industrial wastewater, comprising a multi-chamber electrodialysis system, a high-multiple concentration system, a distillation and extraction system, and a cooling and crystallization system; wherein the multi-chamber electrodialysis system comprises a pretreatment unit and an electrodialysis unit to separate organic matter and valuable substances in the wastewater; the high-multiple concentration system performs high-multiple concentration on the separated valuable substances; the distillation and extraction system is used to separate specific ions; and the cooling and crystallization system further separates the remaining ions.

[0007] Pretreatment units include microfiltration and ultrafiltration systems.

[0008] Preferably, the filtration mode includes immersion type, MBR membrane pool type or vibrating membrane type.

[0009] Preferably, the pore size of the filter membrane is 0.2-100 μm.

[0010] Preferably, the filter membrane material includes hollow fiber, polysulfone, polyamide or ceramic.

[0011] The electrodialysis unit comprises an electrodialysis membrane stack, a DC voltage-regulated power supply, a flowmeter, a circulation pump and a water tank; the two ends of the electrodialysis membrane stack are anode plates and cathode plates, the anode plate and the adjacent partition form an anode chamber, the cathode plate and the adjacent partition form a cathode chamber, and at least one membrane unit is arranged between the anode chamber and the cathode chamber; a plurality of ion exchange membranes are arranged in the membrane unit, and a concentrated chamber or a dilute chamber is formed between two ion exchange membranes, and the membrane unit is provided with 1 concentrated chamber and 2-5 dilute chambers, or 1 dilute chamber and 2-5 concentrated chambers, and the concentrated chambers and the dilute chambers can be freely combined according to the target ion recovery principle and efficiency optimization; the water tank comprises an electrode chamber water tank for storing an electrode liquid, a concentrated chamber water tank for storing a separated thiocyanate solution, and a dilute chamber water tank for storing a mixed solution containing thiocyanate ions and impurities and organic matter.

[0012] Preferably, the solutes of the polar liquid in the polar chamber water tank include sodium sulfate, sodium chloride, and sodium nitrate, and the concentration of the solutes is 0.05-0.2 mol / L.

[0013] Preferably, the number of membrane units is 1-50.

[0014] Preferably, the electrodialysis membrane stack voltage is 5-50V, and the electrodialysis membrane stack flow rate is 1000-10000mL / min.

[0015] Preferably, the ion exchange membrane includes a heterogeneous membrane, a homogeneous membrane and an alloy membrane, and the membrane resistance is 0-10Ω / cm 2 The exchange capacity is 1.3-3mol / Kg and the acidity and alkalinity resistance is pH2-10.

[0016] The ion exchange membrane also includes a composite multi-walled carbon nanotube anion exchange membrane, wherein the preparation steps of the composite multi-walled carbon nanotube anion exchange membrane are: acidifying, aminating, and vinylizing the multi-walled carbon nanotubes to obtain vinyl-functionalized multi-walled carbon nanotubes; polymerizing and grafting the vinyl-functionalized multi-walled carbon nanotubes with a modifier to obtain composite multi-walled carbon nanotubes; and performing a film-forming treatment on the composite multi-walled carbon nanotubes to obtain a composite multi-walled carbon nanotube anion exchange membrane.

[0017] Preferably, the modifier includes 2-acrylamide-2-methylpropanesulfonic acid and 1-butyl-3-vinyl-1H-imidazol-3-ium bromide, the mass ratio of vinyl functionalized multi-walled carbon nanotubes to 2-acrylamide-2-methylpropanesulfonic acid is 20-200:100-1000, and the mass ratio of vinyl functionalized multi-walled carbon nanotubes to 1-butyl-3-vinyl-1H-imidazol-3-ium bromide is 20-200:60-600; the two form a copolymer chain on the multi-walled carbon nanotube, and the two ion exchange groups of sulfonic acid group and imidazolium cation act synergistically to form a continuous ion conduction channel, thereby improving the selective transmission ability of specific anions; the copolymer structure enhances the cohesion of the membrane through intermolecular interaction, improves the thermal stability and mechanical properties of the membrane, and improves the chemical stability of the membrane, so that it can maintain stable performance in different environments.

[0018] More preferably, the modifier includes 2-acrylamido-2-methylpropanesulfonic acid, 1-butyl-3-vinyl-1H-imidazole-3-ium bromide, and polyethylene glycol dimethacrylate, and the mass ratio of vinyl functionalized multi-walled carbon nanotubes to polyethylene glycol dimethacrylate is 20-200:10-100; polyethylene glycol dimethacrylate has a double bond structure at both ends of the molecule, and can be connected with two or more polymer chains to form covalent bonds at the same time, connecting the originally relatively independent polymer chains together to construct a three-dimensional cross-linked network structure, which can limit the relative movement of the polymer chains and make the anion exchange membrane have better mechanical strength and stability; optimize the microstructure of the membrane, adjust the pore size and porosity, make it more effective in the selective transmission of different ions, and improve the ion selectivity of the membrane.

[0019] The high-power concentration system uses RO reverse osmosis for mid-stage concentration, including a bottom plate, a protective block, a sleeve, a connecting rod, a spring, a column and a top frame; a reverse osmosis treatment structure is arranged on the bottom plate; the protective block surrounds the bottom plate and is connected to the bottom plate through a sleeve and a connecting rod, and a spring is arranged between the connecting rod and the sleeve; columns are vertically fixed at the four corners of the bottom plate, and the top of the column is connected to the top frame; the reverse osmosis treatment structure includes a booster pump, a quartz sand filter, an activated carbon filter, a softening resin filter, a reverse osmosis tube and a precision filter; RO reverse osmosis adopts a multi-stage type, and the RO membrane element adopts a rolled membrane element.

[0020] Preferably, the particle size of the separation and sieving is 0.1-0.9 nm.

[0021] Preferably, the designed membrane flux is 10-20LMH.

[0022] The distillation extraction system includes a distillation tower, an extractant adding device, a reflux system, a collecting device and a temperature and pressure control system; the distillation tower is provided with a plurality of distillation zones, each of which has different temperatures and pressures; the extractant adding device includes a metering pump and a nozzle with adjustable angle and direction, which is used to add the extractant to the distillation zone.

[0023] The cooling crystallization system includes a vertical cylindrical container-shaped shell, a flat cover, a material distribution device, a scraper device, a conical head, a cooling coil and a cooling medium distribution pipe; multiple groups of cooling coils in the shell are connected to the cooling medium distribution pipe to form multiple single crystallizers connected in sequence, and each layer of the cooling coils is hexagonal and is arranged on a multifunctional lifting pipe connected to a hydraulic lifting device.

[0024] A method for efficiently recovering valuable substances in industrial wastewater in steps, comprising the following steps: pretreating the industrial wastewater in a pretreatment unit; introducing the pretreated wastewater into a multi-chamber electrodialysis system to separate salt and organic matter; and introducing the effluent from the electrodialysis concentration chamber into a high-multiple concentration system, a distillation extraction system, and a cooling crystallization system in sequence for treatment to recover the valuable substances.

[0025] The present invention also provides a multi-chamber electrodialysis system, comprising a pretreatment unit and an electrodialysis unit.

[0026] The pretreatment unit includes microfiltration and ultrafiltration systems. Place the filter membrane flat in the filter membrane installation cavity and seal the edge of the filter membrane with a sealing strip; connect the water inlet of the pretreatment equipment to the wastewater source, connect the water outlet to the water inlet of the electrodialysis unit, and use a pipe clamp to firmly fix the pipe interface.

[0027] Preferably, the filtration mode includes immersion type, MBR membrane pool type or vibrating membrane type.

[0028] Preferably, the pore size of the filter membrane is 0.2-100 μm.

[0029] Preferably, the filter membrane material includes hollow fiber, polysulfone, polyamide or ceramic.

[0030] The electrodialysis unit includes an electrodialysis membrane stack, a DC regulated power supply, a flow meter, a circulation pump, and a water tank. The two ends of the membrane stack are positive electrode plates and negative electrode plates; the anode plate and the adjacent partition form an anode chamber, the cathode plate and the adjacent partition form a cathode chamber, a membrane unit is arranged between the anode chamber and the cathode chamber, and when the membrane unit is repeated in multiples, the multiple membrane units are arranged closely together; multiple ion exchange membranes are arranged in the membrane unit, the ion exchange membranes include cation exchange membranes and anion exchange membranes, and a concentrated chamber or a dilute chamber is formed between the two ion exchange membranes. The membrane unit is provided with 1 concentrated chamber and 2-5 dilute chambers, or 1 dilute chamber and 2-5 concentrated chambers. The concentrated chamber and the dilute chamber can be freely combined according to the target ion recovery principle and efficiency optimization, such as concentrated-concentrated-dilute, dilute-dilute-concentrated, concentrated-concentrated-concentrated-dilute, etc.; the anode chamber is provided with an anode liquid inlet and an anode liquid outlet, the cathode chamber is provided with a cathode liquid inlet and a cathode liquid outlet, the concentrated chamber is provided with a concentrated water inlet and a concentrated water outlet, and the dilute chamber is provided with a fresh water inlet and a fresh water outlet; the partition is a partition commonly used in the field of electrodialysis. The water tank includes a polar chamber water tank for storing polar liquid, a concentrated chamber water tank for storing separated thiocyanate solution, and a dilute chamber water tank for storing a mixed solution containing thiocyanate ions, impurities, and organic matter; the polar chamber water tank is connected to both sides of the electrode plate through a conduit, and a polar liquid circulation loop is established through a circulating pump; the concentrated chamber water tank is connected to the concentrated water inlet and concentrated water outlet through a conduit, so that the concentrated water flows from the concentrated chamber water tank in sequence into the membrane stack and then flows back to the concentrated chamber water tank; the dilute chamber water tank is connected to the dilute water inlet and dilute water outlet through a conduit, so that the mixed solution flows from the dilute chamber water tank in sequence into the membrane stack and then flows back to the dilute chamber water tank. The negative pole of the DC regulated power supply is connected to the cathode of the membrane stack, and the positive pole is connected to the anode of the membrane stack.

[0031] Preferably, the number of membrane units is 1-50.

[0032] More preferably, the number of membrane units is 5-20.

[0033] Preferably, the ion exchange membrane includes heterogeneous membrane, homogeneous membrane and alloy membrane, wherein the membrane resistance is 0-10Ω / cm 2 , the exchange capacity is 1.3-3mol / Kg, and the acidity and alkalinity resistance is pH2-10.

[0034] The invention also provides a high-multiple concentration system, which comprises a bottom plate, a protection block, a sleeve, a connecting rod, a spring, a column and a top frame.

[0035] Install the booster pump and quartz sand filter on the bottom plate in sequence, and connect the components with pipes according to the process to ensure tight connection and no leakage; install protective blocks around the bottom plate, connect them to the bottom plate through sleeves and connecting rods, and install springs between the connecting rods and sleeves; vertically fix columns at the four corners of the bottom plate, connect the top frame at the top, and install retaining bars between adjacent columns; install rollers at the four corners of the bottom surface of the bottom plate, and install a receiving tray at the bottom, ensuring that the receiving tray edge plate and the bottom plate support strip are nested and matched. Install the control panel on the column and connect the circuits of each component.

[0036] Preferably, the reverse osmosis membrane adopts a single-stage or multi-stage type.

[0037] Preferably, the RO membrane element is a spiral membrane element.

[0038] Preferably, the particle size of the separation and screening is 0.1-0.9 nm, and the designed membrane flux is 10-20 LMH.

[0039] The present invention also provides a rectification and extraction system, comprising a rectification tower, an extractant adding device, a reflux system, a collecting device, and a temperature and pressure control system.

[0040] Build a distillation tower, set up the distillation area, and open the feed and discharge ports; install the extractant adding device, connect the metering pump to the nozzle and fix it in the middle of the distillation tower; connect the reflux system, connect the top and bottom collecting devices of the distillation tower with pipes, and install related valves; install the temperature and pressure control system, connect the sensors and control equipment; set up the extractant storage tank, extractant regeneration device and extractant circulation pump, connect them into a recovery system with pipes, and connect them to the distillation tower.

[0041] The present invention also provides a cooling crystallization system, comprising: a vertical cylindrical container-shaped shell, a flat cover, a material distribution device, a material scraping device, a conical head, a cooling coil and a cooling medium distribution pipe.

[0042] A vertical cylindrical container-shaped shell is installed, a cooling coil is installed in the shell, and the cooling coil is connected to the cooling medium distribution pipe so that each layer of cooling coil is hexagonal and fixed on the multifunctional lifting pipe; a flat cover is installed on the top of the shell, and a material distribution device is installed; a conical head and a scraper device are installed on the bottom; a hydraulic lifting device is installed on the flat cover and connected to the multifunctional lifting pipe, and the hydraulic lifting device includes a rigid connecting frame, a hydraulic cylinder, and a hydraulic pump station; a seed crystal circulation pipeline is connected outside the shell.

[0043] The present invention also provides a method for preparing a composite multi-walled carbon nanotube anion exchange membrane, comprising: Preparation of carboxylated multi-walled carbon nanotubes: MWNTs are dispersed in a mixed acid solution of concentrated nitric acid and concentrated sulfuric acid, stirred and refluxed at 85-95°C for 6-8 hours, then cooled to room temperature, vacuum filtered, and washed with deionized water until the pH of the washing solution is 6.9-7.1, and vacuum dried at 85-95°C for 8-12 hours to obtain MWNT-COOH.

[0044] Preferably, in the mixed acid solution, the volume ratio of concentrated nitric acid to concentrated sulfuric acid is 6-60:2-20.

[0045] Preferably, the mass volume ratio of MWNT to mixed acid is 20-200 mg:8-80 mL.

[0046] Preparation of amine-functionalized multi-walled carbon nanotubes: Disperse MWNT-COOH in DMF, add ethylenediamine, EDC, and DMAP, mix ultrasonically for 15-45 minutes, react at 85-95°C for 18-30 hours, then cool to room temperature, vacuum filter, wash with deionized water, and vacuum dry at 50-70°C for 8-12 hours to obtain MWNT-NH2.

[0047] Preferably, the mass volume ratio of MWNT-COOH to DMF is 20-200 mg:25-250 mL.

[0048] Preferably, the mass volume ratio of MWNT-COOH to ethylenediamine is 20-200 mg:10-100 mL.

[0049] Preferably, the mass ratio of MWNT-COOH to EDC is 20-200:30-300.

[0050] Preferably, the mass ratio of MWNT-COOH to DMAP is 20-200:30-300.

[0051] Preparation of vinyl-functionalized multi-walled carbon nanotubes: Disperse MWNT-NH2 in DMF, add acrylic acid, EDC, and DMAP, and mix ultrasonically for 10-30 minutes. React at 45-55°C with stirring for 18-30 hours, then cool to room temperature, vacuum filter, wash with deionized water, and vacuum dry at 45-55°C for 8-12 hours to obtain MWNT-CH=CH2, i.e., vinyl-functionalized multi-walled carbon nanotubes.

[0052] Preferably, the mass volume ratio of MWNT-NH2 to DMF is 20-200 mg:25-250 mL.

[0053] Preferably, the mass volume ratio of MWNT-NH2 to acrylic acid is 20-200 mg:10-100 mL.

[0054] Preferably, the mass ratio of MWNT-NH2 to EDC is 20-200:30-300.

[0055] Preferably, the mass ratio of MWNT-NH2 to DMAP is 20-200:30-300.

[0056] Preparation of composite multi-walled carbon nanotubes: MWNT-CH=CH2 is dispersed in deionized water to form a MWNT-CH=CH2 dispersion, potassium persulfate is added at 45-55°C under nitrogen protection, and stirred for 10-30 minutes, modifiers AMPS and BVImBr are added, and stirred evenly, the temperature is raised to 75-85°C, and the mixture is reacted under stirring conditions and nitrogen protection for 8-12 hours, then cooled to room temperature, vacuum filtered, and washed alternately with deionized water and ethanol, and dried at 65-75°C for 8-12 hours to obtain P(AMPS-BVImBr)-g-MWCNTs, i.e. composite multi-walled carbon nanotubes.

[0057] Preferably, in the MWNT-CH=CH2 dispersion, the mass volume ratio of MWNT-CH=CH2 to deionized water is 20-200 mg:10-100 mL.

[0058] Preferably, the mass ratio of MWNT-CH=CH2 to potassium persulfate is 20-200:20-200.

[0059] Preferably, the modifier includes AMPS and BVImBr, the mass ratio of MWNT-CH=CH2 to AMPS is 20-200:100-1000, and the mass ratio of MWNT-CH=CH2 to BVImBr is 20-200:60-600.

[0060] More preferably, the modifier includes AMPS, BVImBr, and PEGDMA, the mass ratio of MWNT-CH=CH2 to AMPS is 20-200:100-1000, the mass ratio of MWNT-CH=CH2 to BVImBr is 20-200:60-600, and the mass ratio of MWNT-CH=CH2 to PEGDMA is 20-200:10-100.

[0061] Preparation of composite multi-walled carbon nanotube anion exchange membrane: disperse the composite multi-walled carbon nanotubes in DMF, ultrasonicate for 45-90 min to obtain a uniform dispersion, add polyvinyl alcohol, ultrasonicate for 15 min, add glutaraldehyde, ultrasonicate for 15-45 min, and evenly coat on a glass plate to form a liquid film. Vacuum dry at 65-75 ° C for 8-12 h to obtain a solid membrane. After stripping, soak in deionized water for 18-30 h, and vacuum dry for 10-12 h to obtain a composite multi-walled carbon nanotube anion exchange membrane.

[0062] Preferably, the mass volume ratio of the composite multi-walled carbon nanotubes to DMF is 20-200:2-20 mL.

[0063] Preferably, the mass ratio of the composite multi-walled carbon nanotubes to the polyvinyl alcohol is 20-200:10-100.

[0064] Preferably, the mass ratio of the composite multi-walled carbon nanotubes to glutaraldehyde is 20-200:1-10.

[0065] The present invention also provides a method for efficiently distributing and recovering valuable substances in industrial wastewater, comprising: Pretreatment of wastewater: Take the wastewater generated in the production process of pharmaceutical companies, remove particulate matter and suspended matter through a microfiltration pretreatment unit to obtain pretreated wastewater.

[0066] Electrodialysis separation: Add corresponding solutions to each water tank of the device, including: add polar solution to the polar chamber water tank; introduce pure water to the concentrated chamber water tank; introduce pre-treated wastewater to the dilute chamber water tank. Then turn on the circulation pump corresponding to each water tank, that is, turn on the circulation pump set on the conduit connecting each water tank and the corresponding compartment in the membrane stack, and adjust the corresponding circulation flow rate. Then turn on the DC power supply. When the conductivity is observed to be stable, it is regarded as the end point of the reaction, stop the treatment, and turn off the power supply.

[0067] Preferably, the solutes of the polar liquid in the polar chamber water tank include sodium sulfate, sodium chloride, and sodium nitrate, and the concentration of the solutes is 0.05-0.2 mol / L.

[0068] More preferably, the solute is sodium sulfate with a concentration of 0.05-0.1 mol / L.

[0069] Preferably, the volume of the cathode chamber water tank, the concentration chamber water tank, and the dilution chamber water tank are all 5L.

[0070] Preferably, the electrodialysis membrane stack voltage is 5-50V, and the electrodialysis membrane stack flow rate is 1000-10000mL / min.

[0071] Preferably, the rotation speed of the circulation pump is maintained at 600-800 rpm.

[0072] Electrodialysis concentration: The effluent from the concentration chamber in the electrodialysis separation is introduced into the electrodialysis concentration system for concentration. The operation steps are the same as those of the electrodialysis primary separation system.

[0073] Preferably, the electrodialysis concentration comprises multi-stage batch mode, multi-stage semi-batch mode or volume difference concentration.

[0074] High-fold concentration: The effluent from the concentration chamber in the electrodialysis concentration chamber is introduced into the RO reverse osmosis device, and the booster pump is turned on to allow the wastewater to pass through each filter device and reverse osmosis tube in turn for high-fold concentration.

[0075] Preferably, RO reverse osmosis adopts a multi-stage design.

[0076] Preferably, the RO membrane element is a spiral membrane element.

[0077] Preferably, the particle size of the separation and sieving is 0.1-0.9 nm.

[0078] Preferably, the membrane flux is designed to be 10-20LMH; Distillation extraction: The highly concentrated liquid of RO reverse osmosis is introduced into the distillation extraction system, and extraction distillation is carried out under normal pressure; the mixture of the extractant and water is distilled through a pipeline to a water distillation kettle, the extractant is recovered, and high-purity glacial acetic acid is collected.

[0079] Preferably, the reflux ratio is controlled to be 1-8.

[0080] Preferably, the tower top temperature is 60-80°C, and the tower bottom temperature is 110-130°C.

[0081] Preferably, the molar ratio of the extractant to the raw material liquid is 1-10:10-100.

[0082] Preferably, the extractant includes acetophenone, N-methylacetamide, methyl pyrrolidone, tributyl phosphate, and isopropyl acetate.

[0083] Cooling crystallization: The separated liquid after extraction is introduced into the cooling crystallization system, and sodium thiocyanate is obtained by cooling crystallization.

[0084] Preferably, the crystallizer temperature is controlled at 0-20°C and the stirring speed is controlled at 500-3000 rpm.

[0085] More preferably, the crystallizer temperature is controlled at 0-10°C and the stirring speed is controlled at 500-2000 rpm.

[0086] Preferably, the wastewater retention time is 1-2 hours.

[0087] The present invention adopts a multi-chamber electrodialysis system, a high-concentration system, a distillation extraction system, and a cooling crystallization system to form a complete set of equipment for efficient step-by-step recovery of valuable substances in industrial wastewater, and adopts a composite multi-walled carbon nanotube anion exchange membrane, and 2-acrylamide-2-methylpropanesulfonic acid and 1-butyl-3-vinyl-1H-imidazol-3-ium bromide and multi-walled carbon nanotubes are polymerized, so it has the following beneficial effects: the device and method provided by the present invention can realize efficient step-by-step recovery of multiple valuable substances from industrial wastewater, the separation process is simple and safe, and the difficult problem of separation and recovery of valuable substances in industrial wastewater is solved. The separation recovery rate of multi-component valuable substances is high, and full resource utilization of salt is realized. The entire process has no pollution discharge, and promotes zero discharge of industrial wastewater. Therefore, the present invention is a complete set of equipment and method for efficient step-by-step recovery of valuable substances in industrial wastewater with high efficiency and pollution-free. BRIEF DESCRIPTION OF THE DRAWINGS

[0088] Figure 1 The present invention is a process flow chart of a complete set of equipment and method for efficient step-by-step recovery of valuable substances in industrial wastewater.

[0089] Figure 2 This is a structural diagram of a multi-chamber electrodialysis device in a complete set of equipment for efficient step-by-step recovery of valuable substances in industrial wastewater.

[0090] Figure 3 It is a schematic diagram of the principle of separating and recovering ions using an electrodialysis membrane stack in a specific embodiment of the present invention.

[0091] Figure 4 This is a schematic diagram of the treatment results of actual industrial wastewater with different salt contents after electrodialysis treatment. DETAILED DESCRIPTION

[0092] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0093] The following first describes the concepts involved in the present application in conjunction with the accompanying drawings. It should be noted that the following description of each concept is only to make the content of the present application easier to understand, and does not limit the scope of protection of the present application; at the same time, the embodiments and features in the embodiments of the present application can be combined with each other in the absence of conflict. The present application will be described in detail with reference to the accompanying drawings and in conjunction with the embodiments.

[0094] Table 1 Abbreviations corresponding to Chinese meanings

[0095] The multi-chamber electrodialysis device used in the present invention is as follows Figure 2 As shown, 1 is an electrodialysis power supply, 2 is an electrodialysis membrane stack, 3 is a membrane stack water inlet, 4 is a membrane stack water outlet, 5 is an electrode plate, 6 is an ion exchange membrane, 7 is a power line, 8 is a conduit, 9 is a discharge tank, 10 is a feed tank, 11 is a polar liquid tank, 12 is a positive electrode of the plate, and 13 is a negative electrode of the plate. The schematic diagram is a certain implementation method to help understanding, and does not constitute a limitation to the present invention.

[0096] The electrodialysis membrane stack used in the present invention is as follows Figure 3 As shown, it is composed of 1 anode and 1 cathode, and includes a cation exchange membrane and an anion exchange membrane, as well as chambers separated by ion exchange membranes. The schematic diagram is a specific implementation method to help understanding, and does not constitute a limitation of the present invention.

[0097] Example 1 A complete set of equipment for efficient step-by-step recovery of valuable substances in industrial wastewater, comprising: a multi-chamber electrodialysis system, a high-concentration system, a distillation extraction system, and a cooling crystallization system; wherein the multi-chamber electrodialysis system comprises a pretreatment unit and an electrodialysis unit.

[0098] The pretreatment unit includes microfiltration and ultrafiltration systems. Place the filter membrane flat in the filter membrane installation cavity and seal the edge of the filter membrane with a sealing strip; connect the water inlet of the pretreatment equipment to the wastewater source, connect the water outlet to the water inlet of the electrodialysis unit, and use a pipe clamp to firmly fix the pipe interface. The filter membrane is made of hollow fiber and the pore size of the filter membrane is 0.32μm.

[0099] The electrodialysis unit includes an electrodialysis membrane stack, a DC voltage-stabilized power supply, a flow meter, a circulation pump, and a water tank. The electrodialysis membrane stack used in this embodiment is provided with one membrane unit, and the membrane unit is provided with one anion exchange membrane, four cation exchange membranes, one dilute chamber, and four concentrate chambers. With the positive electrode plate as the reference plane, the anode plate, homogeneous anion exchange membrane, partition, anion exchange membrane, partition, homogeneous anion exchange membrane, partition, cation exchange membrane, partition, anion exchange membrane are stacked in sequence, and finally the negative electrode plate is covered to form a membrane stack structure; the partition is a partition commonly used in the field of electrodialysis; the water tank includes an electrode chamber water tank for storing the cathode liquid, a concentrate chamber water tank for storing the separated thiocyanate solution, and a dilute chamber water tank for storing a mixed solution containing thiocyanate ions and impurities and organic matter. The water tank of the cathode chamber is connected to both sides of the electrode plate through a conduit, and a circulation pump is used to establish an anode liquid circulation loop; the water tank of the concentration chamber is connected to the concentrated water inlet and the concentrated water outlet through a conduit, so that the concentrated water flows from the concentration chamber water tank into the membrane stack in sequence and then flows back to the concentration chamber water tank; the water tank of the dilute chamber is connected to the fresh water inlet and the fresh water outlet through a conduit, so that the mixed solution flows from the dilute chamber water tank into the membrane stack in sequence and then flows back to the dilute chamber water tank; the negative pole of the DC regulated power supply is connected to the cathode of the membrane stack, and the positive pole is connected to the anode of the membrane stack. Both the anion exchange membrane and the cation exchange membrane are homogeneous membranes with a membrane resistance of 8Ω / cm 2 , the exchange capacity is 1.5mol / Kg, and the acidity and alkalinity resistance is pH2-10.

[0100] The high concentration system includes a bottom plate, a protective block, a sleeve, a connecting rod, a spring, a column and a top frame. The booster pump, quartz sand filter, activated carbon filter, softening resin filter, reverse osmosis tube and precision filter are installed on the bottom plate in sequence. The components are connected by pipes to ensure tight connection and no leakage, and a control panel is installed on one of the columns; rollers are installed at the four corners of the lower surface of the bottom plate, and a receiving plate is installed at the bottom. Edge plates are set at both ends of the receiving plate, which are nested with the support strips at both ends of the bottom of the bottom plate; protective blocks are installed around the bottom plate, connected to the bottom plate through sleeves and connecting rods, and springs are installed between the connecting rods and sleeves; columns are fixed vertically at the four corners of the bottom plate, the top is connected to the top frame, and baffles are installed between adjacent columns; the control panel is installed on the column, and the circuits of each component are connected. The reverse osmosis membrane adopts a multi-stage type, and the RO membrane element adopts a roll membrane element. The separation and screening particle size is 0.45nm, and the designed membrane flux is 15LMH.

[0101] The distillation extraction system includes a distillation tower, an extractant adding device, a reflux system, a collecting device, and a temperature and pressure control system. The distillation tower is equipped with three distillation zones. The metering pump and nozzle of the extractant adding device are installed in the middle of the distillation tower. The nozzle can adjust the angle and direction so that the extractant can be evenly sprayed into the distillation zone; the reflux system connects the top and bottom of the distillation tower; the collecting device is set at the bottom of the distillation tower, and the temperature and pressure control system is connected to the distillation tower; the extractant storage tank, extractant regeneration device and extractant circulation pump of the extractant recovery system are installed and connected.

[0102] The cooling crystallization system includes a shell, a flat cover, a material distribution device, a scraper device, a conical head, a cooling coil and a cooling medium distribution pipe. The shell is a vertical cylindrical container with multiple groups of cooling coils arranged inside. Each layer of cooling coils is hexagonal and arranged on a multifunctional lifting pipe. The multifunctional lifting pipe is connected to the hydraulic lifting device on the flat cover, forming multiple single crystallizers connected in sequence from top to bottom. Each crystallizer is a multi-layer polygonal cooling coil wound by a straight pipe. The pipes between layers are connected by three-dimensional elbows and are staggered with each other; the hydraulic lifting device is composed of a rigid connecting frame, a hydraulic cylinder, and a hydraulic pump station; the cooling coil is connected to the cooling medium distribution pipe, and a seed circulation pipeline is arranged outside the shell. The material distribution device, the scraper device, and the conical head are installed in place.

[0103] A method for efficient distribution and recovery of valuable substances in industrial wastewater: Pretreatment of wastewater: antibiotic wastewater generated in the production process of pharmaceutical companies is taken, and particulate matter and suspended matter are removed through a microfiltration pretreatment unit to obtain pretreated wastewater; the wastewater contains 7000 mg / L of thiocyanate, 10000 mg / L of chloride ions, and 8000 mg / L of acetate ions.

[0104] Electrodialysis separation: Add the corresponding solutions to each water tank of the device, including: add 5L of sodium sulfate solution with a concentration of 0.1mol / L to the polar chamber water tank; introduce 5L of pure water to the concentrated chamber water tank; introduce 5L of pretreated wastewater to the dilute chamber water tank. Then turn on the circulation pump corresponding to each water tank, that is, turn on the circulation pump set on the conduit connecting each water tank and the corresponding compartment in the membrane stack, adjust the corresponding circulation flow rate, and control the membrane stack flow rate to 3L / min. Then turn on the DC power supply, under the constant voltage state, the voltage is controlled at 20V, the speed of the circulation pump is 700rpm, and when the conductivity is observed to be stable, it is regarded as the end of the reaction, stop the treatment, and turn off the power.

[0105] High-fold concentration: Introduce the effluent from the electrodialysis concentration chamber into the RO reverse osmosis device, turn on the booster pump, and allow the wastewater to pass through each filter device and reverse osmosis tube in turn for high-fold concentration to obtain a high-fold concentrated liquid.

[0106] Distillation extraction: The highly concentrated liquid is introduced into the distillation extraction system, and the extraction distillation is carried out under normal pressure. The reflux ratio is controlled to be 4, the top temperature is 70°C, and the bottom temperature is 120°C. Acetophenone is selected as the extractant, and the molar ratio of the extractant to the raw material liquid is 5:1. The mixture of the extractant and water is distilled in a water distillation kettle through a pipeline, the extractant is recovered, and high-purity glacial acetic acid is collected; the concentrated water after extraction is ultrafiltered and UV disinfected, and then enters the biological treatment system for biological treatment.

[0107] Cooling crystallization: The separated liquid after extraction is introduced into the cooling crystallization system, the crystallizer temperature is controlled to be 5°C, the stirring speed is 1000rpm, the wastewater residence time is 1.5h, and sodium thiocyanate is obtained by cooling crystallization.

[0108] Example 2: Compared with Example 1, the only difference between this example and Example 1 is that the anion exchange membrane in the electrodialysis unit is a composite multi-walled carbon nanotube anion exchange membrane.

[0109] Preparation of composite multi-walled carbon nanotube anion exchange membrane, comprising: Preparation of carboxylated multi-walled carbon nanotubes: MWNTs were dispersed in a mixed acid solution of concentrated nitric acid and concentrated sulfuric acid, stirred and refluxed at 90°C for 7 hours, cooled to room temperature, vacuum filtered, washed with deionized water until the pH of the washing solution was 7.0, and vacuum dried at 90°C for 10 hours to obtain MWNT-COOH, i.e., carboxylated multi-walled carbon nanotubes. In the mixed acid solution, the volume ratio of concentrated nitric acid to concentrated sulfuric acid was 30:10; the mass volume ratio of MWNT to mixed acid was 100 mg:40 mL.

[0110] Preparation of amine-functionalized multi-walled carbon nanotubes: MWNT-COOH was dispersed in DMF, ethylenediamine, EDC, and DMAP were added, and ultrasonic mixing was performed for 30 minutes. After reacting at 90°C for 24 hours, the mixture was cooled to room temperature, vacuum filtered, washed with deionized water, and vacuum dried at 60°C for 10 hours to obtain MWNT-NH2, i.e., amine-functionalized multi-walled carbon nanotubes. The mass volume ratio of MWNT-COOH to DMF was 40mg:50mL; the mass volume ratio of MWNT-COOH to ethylenediamine was 40mg:20mL; the mass ratio of MWNT-COOH to EDC was 40:60; and the mass ratio of MWNT-COOH to DMAP was 40:60.

[0111] Preparation of vinyl functionalized multi-walled carbon nanotubes: MWNT-NH2 was dispersed in DMF, acrylic acid, EDC, and DMAP were added, and ultrasonic mixing was performed for 15 minutes. After reacting at 50°C with stirring for 24 hours, the mixture was cooled to room temperature, vacuum filtered, washed with deionized water, and vacuum dried at 50°C for 10 hours to obtain MWNT-CH=CH2, i.e., vinyl functionalized multi-walled carbon nanotubes. The mass volume ratio of MWNT-NH2 to DMF was 40mg:50mL; the mass volume ratio of MWNT-NH2 to acrylic acid was 40mg:20mL; the mass ratio of MWNT-NH2 to EDC was 40:60; and the mass ratio of MWNT-NH2 to DMAP was 40:60.

[0112] Preparation of composite multi-walled carbon nanotubes: MWNT-CH=CH2 was dispersed in deionized water to form a MWNT-CH=CH2 dispersion. Potassium persulfate was added at 50°C under nitrogen protection, stirred for 15 minutes, AMPS and BVImBr were added, stirred evenly, the temperature was raised to 80°C, reacted under stirring and nitrogen protection for 10 hours, and then cooled to room temperature. After vacuum filtration, it was alternately washed with deionized water and ethanol, and dried at 70°C for 10 hours to obtain P(AMPS-BVImBr)-g-MWCNTs, i.e. composite multi-walled carbon nanotubes. In the MWNT-CH=CH2 dispersion, the mass volume ratio of MWNT-CH=CH2 to deionized water was 40mg:20mL; the mass ratio of MWNT-CH=CH2 to potassium persulfate was 40:40; the mass ratio of MWNT-CH=CH2 to AMPS was 40:200; and the mass ratio of MWNT-CH=CH2 to BVImBr was 40:120.

[0113] Preparation of composite multi-walled carbon nanotube anion exchange membrane: disperse composite multi-walled carbon nanotubes in DMF, ultrasonicate for 1 hour to obtain a uniform dispersion, add polyvinyl alcohol, ultrasonicate for 15 minutes, add glutaraldehyde, ultrasonicate for 30 minutes, uniformly coat on a glass plate to form a liquid film, vacuum dry at 70°C for 10 hours to obtain a solid film, soak in deionized water for 24 hours after stripping, and vacuum dry for 8 hours to obtain a composite multi-walled carbon nanotube anion exchange membrane. The mass volume ratio of composite multi-walled carbon nanotubes to DMF is 100:10mL, the mass ratio of composite multi-walled carbon nanotubes to polyvinyl alcohol is 100:50; the mass ratio of composite multi-walled carbon nanotubes to glutaraldehyde is 100:5.

[0114] Example 3: Compared with Example 2, the difference between this example is the preparation of composite multi-walled carbon nanotubes.

[0115] Preparation of composite multi-walled carbon nanotubes: MWNT-CH=CH2 was dispersed in deionized water to form a MWNT-CH=CH2 dispersion. Potassium persulfate was added at 50°C under nitrogen protection, stirred for 15 minutes, AMPS and BVImBr were added, stirred evenly, the temperature was raised to 80°C, reacted under stirring and nitrogen protection for 10 hours, and then cooled to room temperature. After vacuum filtration, it was alternately washed with deionized water and ethanol, and dried at 70°C for 10 hours to obtain P(AMPS-BVImBr)-g-MWCNTs, i.e. composite multi-walled carbon nanotubes. In the MWNT-CH=CH2 dispersion, the mass volume ratio of MWNT-CH=CH2 to deionized water was 40mg:20mL; the mass ratio of MWNT-CH=CH2 to potassium persulfate was 40:40; the mass ratio of MWNT-CH=CH2 to AMPS was 40:200; and the mass ratio of MWNT-CH=CH2 to BVImBr was 40:200.

[0116] Example 4: Compared with Example 2, the only difference between this example and Example 2 is the preparation of composite multi-walled carbon nanotubes.

[0117] Preparation of composite multi-walled carbon nanotubes: MWNT-CH=CH2 was dispersed in deionized water to form a MWNT-CH=CH2 dispersion. Potassium persulfate was added at 50°C under nitrogen protection and stirred for 15 minutes. AMPS, BVImBr and PEGDMA were added and stirred evenly. The temperature was raised to 80°C. The mixture was reacted under stirring and nitrogen protection for 10 hours and then cooled to room temperature. After vacuum filtration, the mixture was washed alternately with deionized water and ethanol and dried at 70°C for 10 hours to obtain P(AMPS-BVImBr)-g-MWCNTs, i.e. composite multi-walled carbon nanotubes. In the MWNT-CH=CH2 dispersion, the mass volume ratio of MWNT-CH=CH2 to deionized water is 40 mg:20 mL; the mass ratio of MWNT-CH=CH2 to potassium persulfate is 40:40; the mass ratio of MWNT-CH=CH2 to AMPS is 40:200; the mass ratio of MWNT-CH=CH2 to BVImBr is 40:120; and the mass ratio of MWNT-CH=CH2 to PEGDMA is 40:40.

[0118] Example 5: The difference between this example and Example 2 lies only in the preparation of composite multi-walled carbon nanotubes.

[0119] Preparation of composite multi-walled carbon nanotubes: MWNT-CH=CH2 was dispersed in deionized water to form a MWNT-CH=CH2 dispersion. Potassium persulfate was added at 50°C under nitrogen protection and stirred for 15 minutes. AMPS, BVImBr and PEGDMA were added and stirred evenly. The temperature was raised to 80°C. The mixture was reacted under stirring and nitrogen protection for 10 hours and then cooled to room temperature. After vacuum filtration, the mixture was washed alternately with deionized water and ethanol and dried at 70°C for 10 hours to obtain P(AMPS-BVImBr)-g-MWCNTs, i.e. composite multi-walled carbon nanotubes. In the MWNT-CH=CH2 dispersion, the mass volume ratio of MWNT-CH=CH2 to deionized water is 40 mg:20 mL; the mass ratio of MWNT-CH=CH2 to potassium persulfate is 40:40; the mass ratio of MWNT-CH=CH2 to AMPS is 40:200; the mass ratio of MWNT-CH=CH2 to BVImBr is 40:120; and the mass ratio of MWNT-CH=CH2 to PEGDMA is 40:80.

[0120] Comparative Example 1: This comparative example is different from Example 2 only in that AMPS is not used in the preparation of the composite multi-walled carbon nanotubes.

[0121] Comparative Example 2: This comparative example is different from Example 2 only in that BVImBr is not used in the preparation of composite multi-walled carbon nanotubes.

[0122] Test Example 1: Test on the treatment effect of different salinities of actual industrial wastewater after electrodialysis treatment.

[0123] Test sample: the effluent from the concentration chamber after electrodialysis treatment in Example 1.

[0124] Test method: After the start of the electrodialysis reaction, water samples are collected from the outlet of the concentration chamber every 15 minutes for 60 minutes; the thiocyanate ions are complexed with the iron ions and determined by ultraviolet spectrophotometry, and the separation efficiency and selectivity are evaluated based on the thiocyanate ion concentration; the ion change concentrations of sulfate ions, phosphate ions, chloride ions, and acetate ions are detected based on ion chromatography, and the TOC content is determined using a total organic carbon molecular analyzer.

[0125] The actual treatment effect of industrial wastewater with different salts after electrodialysis treatment is as follows Figure 4 As shown, it shows that the electrodialysis system has a good separation and concentration effect on thiocyanate ions, phosphate ions, chloride ions, acetate ions and organic pollutants in the wastewater, and can effectively reduce the content of related ions and organic matter in the freshwater wastewater.

[0126] Test Example 2: Ion exchange capacity test of anion exchange membrane.

[0127] Test samples: anion exchange membranes prepared in Examples 2-5 and Comparative Examples 1-2.

[0128] Test method: Cut the anion exchange membrane into squares of the same size, weigh them, soak them in a certain volume of 1 mol / L sodium chloride solution at 25°C with stirring for 24 hours, rinse them with deionized water, take the supernatant, and determine the remaining sodium ion concentration in the solution with an ion chromatograph.

[0129] The ion exchange capacity is calculated as follows:

[0130] Where: Q is the ion exchange capacity, c 1 is the initial sodium ion concentration, c 2 is the residual sodium ion concentration, V is the volume of sodium chloride solution, and m is the mass of the anion exchange membrane.

[0131] The test results of the ion exchange capacity of the anion exchange membrane prepared by the present invention are shown in Table 2: Table 2 Test results of ion exchange capacity of anion exchange membrane

[0132] Compared with Comparative Example 1-2, the anion exchange membrane of Example 2-3 adopts a composite multi-walled carbon nanotube anion exchange membrane obtained by polymerization reaction of 2-acrylamide-2-methylpropanesulfonic acid and 1-butyl-3-vinyl-1H-imidazol-3-ium bromide with multi-walled carbon nanotubes, and its ion exchange capacity reaches 3.2-3.5mmol / g, which is much higher than Comparative Example 1-2, indicating that the two ion exchange groups of sulfonic acid group and imidazolium cation are indispensable, and they work synergistically to form a continuous ion conduction channel, improve the selective transmission capacity of specific anions, and thus facilitate ion exchange and improve the ion exchange capacity. In Example 4-5, polyethylene glycol dimethacrylate was introduced in the preparation process of composite multi-walled carbon nanotubes, and the ion exchange capacity was further increased to, indicating that the addition of polyethylene glycol dimethacrylate changed the chemical structure and interchain interaction of the membrane, optimized the membrane structure, enhanced the hydrophilicity of the membrane, and made it easier for ions to diffuse and exchange in the membrane, thereby improving the ion exchange capacity.

[0133] Test Example 3: Average salt rejection rate test of anion exchange membrane.

[0134] Test samples: anion exchange membranes prepared in Examples 2-5 and Comparative Examples 1-2.

[0135] Test method: Cut the anion exchange membrane into the same size and install it in the electrodialysis device. Add a certain volume of 0.1mol / L sodium chloride solution into the desalination chamber of the electrodialysis device. Add appropriate amount of deionized water into the anode chamber and cathode chamber at the same time. Under stirring conditions, turn on the DC power supply and start the electrodialysis desalination experiment. Take out 5mL of solution from the desalination chamber every 10 minutes, measure its conductivity with a conductivity meter, and continue for 60 minutes to calculate the average desalination rate of the whole experimental process.

[0136] The salt rejection rate at each time point was calculated as follows:

[0137] Where: R is the desalination rate, C 0 is the concentration of the initial sodium chloride solution, C t is the concentration of sodium chloride solution in the desalination chamber at time t.

[0138] The test results of the ion exchange capacity of the anion exchange membrane prepared by the present invention are shown in Table 3: Table 3 Average salt rejection test results of anion exchange membrane

[0139] The average desalination rate of Example 2-3 is much higher than that of Comparative Example 1-2, indicating that the sulfonic acid group and the imidazolium cation two ion exchange groups work together to form a more ideal ion transmission environment, which can more effectively block the passage of anions in the salt, improve the selective repulsion of specific anions, and thus facilitate the desalination process and improve the average desalination rate. In Example 4-5, polyethylene glycol dimethacrylate was introduced during the preparation of composite multi-walled carbon nanotubes, and the average desalination rate was further improved, indicating that the addition of polyethylene glycol dimethacrylate changed the chemical structure and interchain interaction of the membrane and optimized the overall performance of the membrane. It may enhance the hydrophilicity of the membrane, making it easier for water molecules to be transported in the membrane, and further adjust the structure and properties of the ion channel, making it more difficult for salt ions to pass through the membrane, making the ion transmission process in the membrane more orderly and efficient, thereby greatly improving the average desalination rate, so that the membrane shows better performance in the desalination process.

[0140] The embodiments and / or implementation methods described above are only used to illustrate the preferred embodiments and / or implementation methods for realizing the technology of the present invention, and are not intended to limit the implementation methods of the technology of the present invention in any form. Any technical personnel in this field may make slight changes or modifications to other equivalent embodiments without departing from the scope of the technical means disclosed in the content of the present invention, but they should still be regarded as technologies or embodiments that are essentially the same as the present invention.

[0141] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and its core ideas of this application. The above is only the preferred implementation method of this application. It should be pointed out that due to the limitations of textual expression and the objective existence of infinite specific structures, ordinary technicians in this technical field can make several improvements, modifications or changes without departing from the principles of this application, and can also combine the above technical features in an appropriate manner; these improvements, modifications, changes or combinations, or the direct application of the concept and technical solution of the invention to other occasions without improvement, should be regarded as the scope of protection of this application.

Claims

1. A complete set of equipment for efficient step-by-step recovery of valuable substances in industrial wastewater, comprising a multi-chamber electrodialysis system, a high-power concentration system, a distillation extraction system, and a cooling crystallization system; wherein: The multi-chamber electrodialysis system includes a pretreatment unit and an electrodialysis unit to separate organic matter and valuable substances in wastewater; the high-concentration system performs high-concentration on the separated valuable substances; the distillation and extraction system is used to separate specific ions; and the cooling crystallization system further separates the remaining ions.

2. A complete set of equipment for efficient step-by-step recovery of valuable substances in industrial wastewater according to claim 1, characterized in that: The pretreatment unit includes a microfiltration and ultrafiltration system, the filtration mode includes an infiltration type, an MBR membrane pool type or a vibrating membrane type, the pore size of the filter membrane is 0.2-100 μm, and the filter membrane material includes hollow fiber, polysulfone, polyamide or ceramic.

3. A complete set of equipment for efficient step-by-step recovery of valuable substances in industrial wastewater according to claim 1, characterized in that: The electrodialysis unit includes an electrodialysis membrane stack, a DC voltage-regulated power supply, a flowmeter, a circulation pump, and a water tank; the two ends of the electrodialysis membrane stack are anode plates and cathode plates, the anode plate and the adjacent partition form an anode chamber, the cathode plate and the adjacent partition form a cathode chamber, and at least one membrane unit is arranged between the anode chamber and the cathode chamber; a plurality of ion exchange membranes are arranged in the membrane unit, and a concentrated chamber or a dilute chamber is formed between two ion exchange membranes, and the membrane unit is provided with 1 concentrated chamber and 2-5 dilute chambers, or 1 dilute chamber and 2-5 concentrated chambers, and the concentrated chambers and the dilute chambers can be freely combined according to the target ion recovery principle and efficiency optimization; the water tank includes an electrode chamber water tank for storing the cathode liquid, a concentrated chamber water tank for storing the separated thiocyanate solution, and a dilute chamber water tank for storing a mixed solution containing thiocyanate ions and impurities and organic matter.

4. A complete set of equipment for efficient step-by-step recovery of valuable substances in industrial wastewater according to claim 3, characterized in that: The solutes of the polar chamber water tank polar liquid include sodium sulfate, sodium chloride, and sodium nitrate, and the solute concentration is 0.05-0.2 mol / L; the number of the membrane units is 1-50; the electrodialysis membrane stack voltage is 5-50V, and the electrodialysis membrane stack flow rate is 1000-10000mL / min; the ion exchange membrane includes heterogeneous membrane, homogeneous membrane and alloy membrane, and the membrane resistance is 0-10Ω / cm 2 , the exchange capacity is 1.3-3mol / Kg, and the acidity and alkalinity resistance is pH2-10.

5. A complete set of equipment for efficient step-by-step recovery of valuable substances in industrial wastewater according to claim 4, characterized in that: The ion exchange membrane also includes a composite multi-walled carbon nanotube anion exchange membrane, wherein the preparation steps of the composite multi-walled carbon nanotube anion exchange membrane are: acidifying, aminating, and vinylating the multi-walled carbon nanotubes to obtain vinyl-functionalized multi-walled carbon nanotubes; The vinyl functionalized multi-walled carbon nanotubes are subjected to polymerization grafting reaction with a modifier to obtain composite multi-walled carbon nanotubes; the composite multi-walled carbon nanotubes are subjected to film-forming treatment to obtain a composite multi-walled carbon nanotube anion exchange membrane.

6. A complete set of equipment for efficient step-by-step recovery of valuable substances in industrial wastewater according to claim 5, characterized in that: The modifier comprises 2-acrylamide-2-methylpropanesulfonic acid and 1-butyl-3-vinyl-1H-imidazole-3-ium bromide; the mass ratio of the vinyl functionalized multi-walled carbon nanotube to the 2-acrylamide-2-methylpropanesulfonic acid is 2-100:10-500; the mass ratio of the vinyl functionalized multi-walled carbon nanotube to the 1-butyl-3-vinyl-1H-imidazole-3-ium bromide is 2-100:6-300.

7. A complete set of equipment for efficient step-by-step recovery of valuable substances in industrial wastewater according to claim 1, characterized in that: The high-power concentration system adopts RO reverse osmosis for mid-stage concentration, and includes a bottom plate, a protective block, a sleeve, a connecting rod, a spring, a column and a top frame; a reverse osmosis treatment structure is arranged on the bottom plate; the protective block surrounds the bottom plate and is connected to the bottom plate through a sleeve and a connecting rod, and a spring is arranged between the connecting rod and the sleeve; columns are vertically fixed at the four corners of the bottom plate, the top of the column is connected to the top frame, and a retaining bar is connected between two adjacent columns, which is flush with the outer surface of the column; the reverse osmosis treatment structure includes a booster pump, a quartz sand filter, an activated carbon filter, a softening resin filter, a reverse osmosis tube and a precision filter; the reverse osmosis membrane adopts a single-stage or multi-stage type, and the RO membrane element adopts a rolled membrane element, the particle size of the separation and screening is 0.1-0.9nm, and the designed membrane flux is 10-20LMH.

8. The complete set of equipment for efficient step-by-step recovery of valuable substances in industrial wastewater according to claim 1 is characterized in that: The distillation extraction system includes a distillation tower, an extractant adding device, a reflux system, a collecting device, and a temperature and pressure control system; the distillation tower is provided with a plurality of distillation zones, each of which has different temperatures and pressures; the extractant adding device includes a metering pump and a nozzle with adjustable angle and direction, which is used to add the extractant to the distillation zone.

9. A complete set of equipment for efficient step-by-step recovery of valuable substances in industrial wastewater according to claim 1, characterized in that: The cooling crystallization system includes a vertical cylindrical container-shaped shell, a flat cover, a material distribution device, a scraper device, a conical head, a cooling coil and a cooling medium distribution pipe; multiple groups of cooling coils in the shell are connected to the cooling medium distribution pipe to form multiple single crystallizers connected in sequence, and each layer of the cooling coils is hexagonal and is arranged on a multifunctional lifting pipe connected to a hydraulic lifting device.

10. A method for efficiently recovering valuable substances in industrial wastewater in steps, which is carried out by a complete set of equipment for efficiently recovering valuable substances in industrial wastewater according to any one of claims 1 to 9, comprising the following steps: The industrial wastewater is pretreated in the pretreatment unit; the pretreated wastewater is introduced into the multi-chamber electrodialysis system to separate salt and organic matter; The effluent from the electrodialysis concentration chamber is sequentially introduced into the high-concentration system, the distillation extraction system, and the cooling crystallization system for treatment to recover valuable substances.

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