A method for separating, recovering and recycling multiple valuable substances from pharmaceutical wastewater

Abstract

The present invention relates to a method for separating, recovering and resource-recycling a variety of valuable substances from pharmaceutical wastewater, using an integrated technology based on electrodialysis to separate and recover thiocyanate ions, chloride ions and acetate ions from pharmaceutical wastewater. The method of the present invention is characterized in that the pharmaceutical wastewater is first pretreated with the aid of a polyacrylonitrile composite nanofiber membrane to remove large particulate matter in the wastewater; the treated wastewater is introduced into an electrodialysis system to separate salts from organic matter in the wastewater; the separated fresh water is introduced into a biological system for biological treatment, and the concentrated water is introduced into an electrodialysis concentration system; the concentrated water after preliminary concentration is introduced into an RO reverse osmosis system for high-multiple concentration, thereby achieving high-multiple concentration and separation and recovery of multi-component salts. The method of the present invention solves the difficult problem of separating and recovering valuable salt molecules in pharmaceutical wastewater, realizes full resource utilization of salts, and the entire process is pollution-free, promoting zero discharge of industrial wastewater.

Description

Technical Field

[0001] The present invention belongs to the field of pharmaceutical wastewater treatment and resource utilization, and specifically relates to a method for separating, recovering and resource utilization of multiple valuable substances from pharmaceutical wastewater. Background Art

[0002] In recent years, with the increasing severity of global climate change and environmental issues, green industrial transformation and the development of new green, low-carbon recycling strategies have become crucial pathways to achieving sustainable economic and social development and overcoming resource and environmental constraints. Industrial wastewater is typically characterized by high salinity, high organic matter concentrations, high suspended solids content, high color, strong odor, high ammonia nitrogen concentrations, and high salt content. Currently, mainstream treatment methods for industrial wastewater, such as physical, biological, and chemical methods, primarily eliminate or remove substances from the wastewater, ignoring the presence of high-value substances such as thiocyanate and acetate. Thiocyanate can be used to produce thiocyanates, esters, various thiocyanides, and cyanides, and is widely used in the chemical, pharmaceutical, and other industries, possessing significant industrial value. Acetate is commonly used in the food industry as a food additive for sodium biacetate, providing acidification and antiseptic properties. It is also used in the dye and pharmaceutical industries.

[0003] Industrial efforts to treat thiocyanate and acetate have primarily focused on promoting recovery and reuse methods, or applying degradation technologies to break down thiocyanates in wastewater into harmless substances. Various methods and technologies have been applied to the separation and recovery of thiocyanate, including adsorption, photodegradation, membrane extraction, coagulation and sedimentation, and advanced oxidation processes. However, these methods present challenges, such as high implementation costs and the generation of other pollutants, resulting in low ion purity after separation and recovery, leading to significant waste.

[0004] Therefore, it is necessary to develop an efficient and low-cost treatment process to separate and recover valuable ions and realize resource utilization. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for efficiently separating, recovering and recycling a variety of valuable substances from pharmaceutical wastewater.

[0006] The technical solutions adopted by the present invention to achieve the above-mentioned purpose are:

[0007] A method for separating, recovering and recycling multiple valuable substances from pharmaceutical wastewater, comprising:

[0008] Pre-treating pharmaceutical wastewater through a pre-treatment unit to remove particulate matter and obtain pre-treated wastewater;

[0009] The pretreated wastewater is introduced into the electrodialysis system to achieve preliminary separation and concentration to obtain separated fresh water and concentrated water;

[0010] The concentrated water is introduced into the RO reverse osmosis system for high-multiple concentration; the concentrated liquid is distilled to obtain glacial acetic acid and separation liquid; the separation liquid is further separated into thiocyanate ions, chloride ions and acetate ions by cooling crystallization, and they are used together in the front-end production; or,

[0011] Adjust the pH of fresh water, intercept glacial acetic acid, and introduce the separated glacial acetic acid into the biological system as a carbon source for biological treatment; the concentrated water is introduced into the electrodialysis concentration system and RO reverse osmosis system, and after concentration and crystallization, the thiocyanate ion and chloride ion are separated, and after concentration adjustment, they can be reused in the front-end process or purified for sale.

[0012] Preferably, the pre-treatment unit comprises a microfiltration and an ultrafiltration system.

[0013] Preferably, the filtration mode includes immersion type, MBR membrane pool type or vibrating membrane type.

[0014] Preferably, the pore size of the filter membrane is 0.2-100 μm.

[0015] Preferably, the filter membrane comprises a polyacrylonitrile composite nanofiber membrane, a hollow fiber membrane, a polysulfone membrane, a polyamide membrane or a ceramic membrane.

[0016] The preparation steps of the polyacrylonitrile composite nanofiber membrane include:

[0017] Calcium lactobionate and α-D-mannose pentaacetate are dissolved in deionized water, tetraethoxysilane is added, and the mixture is stirred to react to form a sol, which is then aged, solvent exchanged, and freeze-dried in vacuo to obtain a modified silica gel.

[0018] Polyacrylonitrile was dissolved in N,N-dimethylformamide to form a uniform solution, deionized water was added to solidify it into balls, and then modified with sodium hydroxide solution and hydrochloric acid solution, and then washed and dried to obtain modified polyacrylonitrile balls.

[0019] The modified silica gel is dispersed in anhydrous ethanol to obtain a modified silica dispersion, modified polyacrylonitrile beads are dissolved in N,N-dimethylformamide, silver nitrate is added to obtain a modified polyacrylonitrile solution, the modified silica dispersion and the modified polyacrylonitrile solution are mixed and sonicated to obtain a composite polyacrylonitrile electrospinning solution;

[0020] The composite polyacrylonitrile electrospinning solution is subjected to electrostatic spinning, modified with a sodium orthovanadate solution, and washed and dried to obtain a polyacrylonitrile composite nanofiber membrane.

[0021] Calcium lactobionate and α-D-mannose pentaacetate were introduced into the formation of modified silica gel to enhance the cross-linking degree of the gel network, so that the generated polyacrylonitrile composite nanofiber membrane has a stable microstructure within the membrane; thereby improving the stability of the polyacrylonitrile composite nanofiber membrane, continuously and stably playing a filtering role in a complex pharmaceutical wastewater environment, making the quality of wastewater entering the electrodialysis system stable, and improving the efficiency of subsequent separation, concentration and other steps; improving the adsorption performance of the polyacrylonitrile composite nanofiber membrane on pollutants in pharmaceutical wastewater, improving the adsorption removal rate and retention rate, and improving the efficiency of the entire wastewater treatment system.

[0022] Calcium lactobionate and α-D-mannose pentaacetate participate in the formation of modified silica gel, affect the sol-gel process, coordinate with the silanol groups generated by the hydrolysis of tetraethoxysilane, and at the same time, through hydrogen bond interactions, further enhance the cross-linking degree of the gel network to build a stable microstructure within the membrane; provide abundant active sites for the polyacrylonitrile composite nanofiber membrane, increase hydrophilicity, and improve adsorption performance; make the polyacrylonitrile composite nanofiber membrane have better mechanical strength and stability, and continuously and stably play a filtering role in the complex pharmaceutical wastewater environment, improve the efficiency of subsequent electrodialysis separation and other steps, and improve the efficiency of the entire wastewater treatment system.

[0023] Preferably, the mass volume ratio of calcium lactobionate to deionized water is 3.2-12.8 g:15-60 mL.

[0024] Preferably, the mass volume ratio of α-D-mannose pentaacetate to deionized water is 3.2-12.8 g:15-60 mL.

[0025] Preferably, the volume ratio of tetraethoxysilane to deionized water is 2.5-10:15-60.

[0026] More preferably, aniline methyl triethoxysilane can be added to the preparation of the modified silica gel, with the volume ratio of aniline methyl triethoxysilane to deionized water being 2.5-10:15-60. This makes the resulting polyacrylonitrile composite nanofiber membrane more structurally stable, allowing it to better withstand changes in pressure and chemical environment during subsequent treatment of pharmaceutical wastewater, and is less likely to deform or break. Optimizing the pore size distribution of the polyacrylonitrile composite nanofiber membrane helps reduce the entry of substances in the wastewater that may interfere with electrodialysis into the system, thereby improving the subsequent electrodialysis system's ability to separate salts and organic matter from pharmaceutical wastewater.

[0027] Preferably, the modified silica gel dispersion is measured by the mass of the modified silica gel therein, and the modified polyacrylonitrile solution is measured by the mass of the modified polyacrylonitrile beads therein, and the mass ratio of the modified silica gel to the modified polyacrylonitrile beads is 1-6:1-6.

[0028] The electrodialysis system 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 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 provided between the anode chamber and the cathode chamber; a plurality of ion exchange membranes are provided in the membrane unit, and a concentrated chamber or a dilute chamber is formed between the two ion exchange membranes, and the concentrated chamber and the dilute chamber 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, miscellaneous salts, and organic matter.

[0029] Preferably, the solutes in the polar liquid of 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.

[0030] Preferably, the number of membrane units is 1-50.

[0031] Preferably, the voltage of the electrodialysis membrane stack is 5-50V, and the flow rate of the electrodialysis membrane stack is 1000-10000 mL / min.

[0032] Preferably, 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.

[0033] Preferably, the RO reverse osmosis comprises a single-stage type or a multi-stage type.

[0034] Preferably, the RO membrane element is a spiral membrane element.

[0035] Preferably, the particle size of the separation and screening is 0.1-0.9 nm, and the designed membrane flux is 10-20 LMH.

[0036] Preferably, the distillation can be performed by batch distillation, continuous distillation, extractive distillation and azeotropic distillation.

[0037] Preferably, the extractive distillation is operated at atmospheric pressure with a reflux ratio of 1-8.

[0038] Preferably, the tower top temperature is 60-80°C.

[0039] Preferably, the bottom temperature is 110-130°C.

[0040] Preferably, the molar ratio of the extractant to the raw material liquid is 1-10:10-100.

[0041] Preferably, the extractant includes acetophenone, N-methylacetamide, methyl pyrrolidone, tributyl phosphate, and isopropyl acetate.

[0042] Preferably, the cooling crystallization is carried out by optimizing the crystallizer temperature of 0-20°C, the stirring speed of 500-3000rpm, and the wastewater residence time of 0.5-3h to control the optimal crystallization conditions.

[0043] The present invention also provides a method for separating, recovering and recycling various valuable substances from pharmaceutical wastewater, comprising:

[0044] Pretreatment of wastewater: Place the filter membrane flat into the filter membrane installation cavity and seal the edge of the filter membrane with sealing strips; connect the water inlet of the pretreatment equipment to the wastewater source, connect the water outlet to the water inlet of the electrodialysis system, and use a pipe clamp to firmly fix the pipe interface; take pharmaceutical wastewater and pass it through the microfiltration pretreatment unit to remove particulate matter and suspended solids to obtain pretreated wastewater.

[0045] Preferably, the filtration mode includes immersion type, MBR membrane pool type or vibrating membrane type.

[0046] Preferably, the filter membrane material includes hollow fiber, polysulfone, polyamide or ceramic.

[0047] Preferably, the pore size of the filter membrane is 0.2-100 μm.

[0048] Electrodialysis separation: The electrodialysis system includes an electrodialysis membrane stack, a DC regulated power supply, a flowmeter, a circulation pump, and a water tank. The two ends of the membrane stack are anodic and cathodic plates. The anode plate and the adjacent separator form the anode chamber, while the cathode plate and the adjacent separator form the cathode chamber. A membrane unit is located between the anode and cathode chambers. When multiple membrane units are repeated, the multiple membrane units are tightly arranged together. The membrane units are equipped with multiple ion exchange membranes, including cation exchange membranes and anion exchange membranes. A concentrate chamber or a dilute chamber is formed between the two ion exchange membranes. The concentrate 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, or concentrated-concentrated-concentrated-dilute. The anode chamber is equipped with an anolyte inlet and an anolyte outlet, the cathode chamber is equipped with a catholyte inlet and an outlet, the concentrate chamber is equipped with a concentrate water inlet and outlet, and the dilute chamber is equipped with a fresh water inlet and outlet. The separators are commonly used in the field of electrodialysis. The water tanks include a cathode chamber tank for storing cathode liquid, a concentrate chamber tank for storing separated thiocyanate solution, and a dilute chamber tank for storing a mixed solution containing thiocyanate ions, miscellaneous salts, and organic matter. The cathode chamber tanks are connected to both sides of the electrode plates via conduits, and a cathode liquid circulation loop is established via a circulating pump. The concentrate chamber tanks are connected to the concentrate water inlet and outlet via conduits, allowing the concentrate water to flow from the concentrate chamber tank into the membrane stack and then back into the concentrate chamber tank. The dilute chamber tanks are connected to the dilute water inlet and outlet via conduits, allowing the mixed solution to flow from the dilute chamber tank into the membrane stack and then back into the dilute chamber 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. Corresponding solutions are added to each water tank of the device, including: cathode liquid is added to the cathode chamber tank; pure water is introduced into the concentrate chamber tank; and pretreated wastewater is introduced into the dilute chamber tank. Next, start the circulation pumps corresponding to each water tank—that is, the pumps located on the conduits connecting each water tank to the corresponding compartments in the membrane stack—and adjust the corresponding circulation flow rates. Then, turn on the DC power supply. When the conductivity stabilizes, the reaction is considered terminated, and the process is stopped and the power supply is turned off.

[0049] Preferably, the number of membrane units is 1-50.

[0050] More preferably, the number of membrane units is 5-20.

[0051] 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.

[0052] Preferably, the solutes in the polar liquid of 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.

[0053] More preferably, the solute is sodium sulfate with a concentration of 0.05-0.1 mol / L.

[0054] Preferably, the volume of the cathode chamber water tank, the concentrate chamber water tank, and the dilute chamber water tank are all 5L.

[0055] Preferably, the voltage of the electrodialysis membrane stack is 5-50V, and the flow rate of the electrodialysis membrane stack is 1000-10000 mL / min.

[0056] Preferably, the rotation speed of the circulation pump is maintained at 600-800 rpm.

[0057] High-fold concentration: The booster pump, quartz sand filter, activated carbon filter, softening resin filter, reverse osmosis tube and precision filter are installed on the base plate in sequence, and the components are connected with 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 base plate, and a receiving tray is installed at the bottom. Edge plates are provided at both ends of the receiving tray, which are nested with the support bars at both ends of the bottom of the base plate; protective blocks are installed around the base plate and connected to the base 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 base plate, connected to the top frame at the top, and retaining bars are installed between adjacent columns; a control panel is installed on the column, and the circuits of each component are connected; the effluent from the electrodialysis concentration chamber is introduced into the RO reverse osmosis device, and the booster pump is turned on to make the wastewater pass through each filtering device and reverse osmosis tube in sequence for high-fold concentration to obtain a high-fold concentrated liquid.

[0058] Preferably, the reverse osmosis membrane adopts a single-stage or multi-stage type.

[0059] Preferably, the RO membrane element is a spiral membrane element.

[0060] Preferably, the particle size of the separation and screening is 0.1-0.9 nm, and the designed membrane flux is 10-20 LMH.

[0061] Distillation extraction: A distillation zone is set up in the distillation tower, and the metering pump and nozzle of the extractant addition 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 collection 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; the high-concentrate liquid of RO reverse osmosis is introduced into the distillation extraction system and extractive distillation is carried out under normal pressure; the mixture of extractant and water is piped to the water still for distillation, the extractant is recovered, and high-purity glacial acetic acid is collected.

[0062] Preferably, the reflux ratio is controlled to be 1-8.

[0063] Preferably, the tower top temperature is 60-80°C, and the tower bottom temperature is 110-130°C.

[0064] Preferably, the molar ratio of the extractant to the raw material liquid is 1-10:10-100.

[0065] Preferably, the extractant includes acetophenone, monomethylacetamide, methyl pyrrolidone, tributyl phosphate, and isopropyl acetate.

[0066] Cooling crystallization: Install a vertical cylindrical container-shaped shell, install a cooling coil inside the shell, connect the cooling coil to the cooling medium distribution pipe, make each layer of cooling coil hexagonal and fixed on the multifunctional lifting pipe; install a flat cover on the top of the shell, install a distribution device; install a conical head and a scraping device at the bottom; install a hydraulic lifting device on the flat cover and connect it to the multifunctional lifting pipe, the hydraulic lifting device includes a rigid connecting frame, a hydraulic cylinder, and a hydraulic pump station; connect the seed crystal circulation pipeline outside the shell; introduce the separated liquid after extraction into the cooling crystallization system, and cool and crystallize to obtain sodium thiocyanate.

[0067] Preferably, the crystallizer temperature is controlled at 0-20°C and the stirring speed is controlled at 500-3000 rpm.

[0068] More preferably, the crystallizer temperature is controlled at 0-10°C and the stirring speed is controlled at 500-2000 rpm.

[0069] Preferably, the wastewater retention time is 1-2 hours.

[0070] The present invention also provides a method for preparing a polyacrylonitrile composite nanofiber membrane, comprising:

[0071] Preparation of modified silica gel: At room temperature, calcium lactobionate and α-D-mannose pentaacetate are dissolved in deionized water, stirred evenly, tetraethoxysilane is added, the pH is adjusted to 3-4, and the mixture is reacted at 35-45°C with stirring for 6-10 hours to form a uniform sol; the sol is aged for 45-50 hours, continuously solvent exchanged with deionized water, and vacuum freeze-dried to obtain the modified silica gel.

[0072] Preferably, the mass volume ratio of calcium lactobionate to deionized water is 3.2-12.8 g:15-60 mL.

[0073] Preferably, the mass volume ratio of α-D-mannose pentaacetate to deionized water is 3.2-12.8 g:15-60 mL.

[0074] Preferably, the volume ratio of tetraethoxysilane to deionized water is 2.5-10:15-60.

[0075] Preferably, the stirring speed is 500-700 rpm.

[0076] Preparation of modified polyacrylonitrile beads: Add polyacrylonitrile to N,N-dimethylformamide under stirring conditions, stir at 45-55°C for 2-4 hours to form a uniform polyacrylonitrile solution; drip the polyacrylonitrile solution into deionized water in the form of droplets, solidify into beads, soak and wash with deionized water to obtain polyacrylonitrile beads; immerse the polyacrylonitrile beads in 1.5-2.5 mol / L sodium hydroxide solution, stir at 55-65°C for 0.5-1.5 hours, wash with deionized water, dry, and then immerse in 0.5-1.5 mol / L hydrochloric acid solution, stir for 1-3 hours, wash with deionized water, and vacuum dry at 45-55°C for 20-30 hours to obtain modified polyacrylonitrile beads.

[0077] Preferably, the mass ratio of polyacrylonitrile to N,N-dimethylformamide is 1-6:9-54.

[0078] Preferably, the stirring speed is 500-700 rpm.

[0079] Preparation of composite polyacrylonitrile electrospinning solution: Disperse modified silica gel in anhydrous ethanol and sonicate for 15-45 minutes to form a uniform modified silica dispersion; dissolve modified polyacrylonitrile beads in N,N-dimethylformamide, stir at 45-55°C for 20-30 hours, add silver nitrate, stir for 0.5-1.5 hours, and sonicate for 5-15 minutes to obtain a modified polyacrylonitrile solution; mix the modified silica dispersion and the modified polyacrylonitrile solution, and sonicate for 20-40 minutes to obtain a composite polyacrylonitrile electrospinning solution.

[0080] Preferably, the mass volume ratio of modified silica gel to anhydrous ethanol is 1-6 g:2-12 mL.

[0081] Preferably, the mass ratio of modified polyacrylonitrile beads to N,N-dimethylformamide is 1-6:9-54.

[0082] Preferably, the mass ratio of silver nitrate to N,N-dimethylformamide is 0.1-0.4:13.5-54.

[0083] Preferably, the modified silica gel dispersion is measured by the mass of the modified silica gel therein, and the modified polyacrylonitrile solution is measured by the mass of the modified polyacrylonitrile beads therein, and the mass ratio of the modified silica gel to the modified polyacrylonitrile beads is 1-6:1-6.

[0084] Preferably, the stirring speed is 500-700 rpm.

[0085] Preparation of polyacrylonitrile composite nanofiber membrane: electrospin the composite polyacrylonitrile electrospinning solution for 4-6 hours to obtain an electrospun fiber membrane; soak the electrospun fiber membrane in a 0.15-0.25 mol / L sodium orthovanadate aqueous solution for 0.5-1.5 hours, wash with deionized water, and vacuum dry at 55-65°C for 20-30 hours to obtain a polyacrylonitrile composite nanofiber membrane.

[0086] Preferably, the electrospinning voltage is 16-20 kV, and the extrusion flow rate is 0.8-1.2 mL / h.

[0087] Preferably, the spinning environment temperature is 23-27° C. and the relative humidity is 20-60%.

[0088] The present invention also provides a method for preparing modified silica gel, comprising:

[0089] Preparation of modified silica gel: At room temperature, calcium lactobionate and α-D-mannose pentaacetate are dissolved in deionized water, stirred evenly, tetraethoxysilane and anilinemethyltriethoxysilane are added, the pH is adjusted to 3-4, and the mixture is reacted at 35-45°C with stirring for 6-10 hours to form a uniform sol; the sol is aged for 45-50 hours, continuously solvent exchanged with deionized water, and vacuum freeze-dried to obtain the modified silica gel.

[0090] Preferably, the mass volume ratio of calcium lactobionate to deionized water is 3.2-12.8 g:15-60 mL.

[0091] Preferably, the mass volume ratio of α-D-mannose pentaacetate to deionized water is 3.2-12.8 g:15-60 mL.

[0092] Preferably, the volume ratio of tetraethoxysilane to deionized water is 2.5-10:15-60.

[0093] Preferably, the volume ratio of anilinemethyltriethoxysilane to deionized water is 2.5-10:15-60

[0094] Preferably, the stirring speed is 500-700 rpm.

[0095] The present invention utilizes a polyacrylonitrile composite nanofiber membrane to pretreat pharmaceutical wastewater. The pretreated wastewater is then introduced into an electrodialysis system, an RO reverse osmosis system, a distillation extraction system, and a cooling crystallization system to separate, recover, and recycle multiple valuable substances from the pharmaceutical wastewater. This method achieves the following beneficial effects: high concentration efficiency and excellent separation of multiple valuable components, and the separation and recovery of salts for reuse in the production process. Therefore, the present invention provides an efficient, pollution-free method for separating, recovering, and reusing multiple valuable substances from pharmaceutical wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0096] Figure 1 The figure is a process flow diagram of a method for separating, recovering and resource-recycling multiple valuable substances from pharmaceutical wastewater.

[0097] Figure 2 The present invention is a schematic diagram of the structure of an electrodialysis device provided in a method for separating, recovering and resource-recovering multiple valuable substances from pharmaceutical wastewater.

[0098] Figure 3 The figure is a schematic diagram of the principle of separating and recovering multi-component valuable substances in a method for separating, recovering and recycling multiple valuable substances from pharmaceutical wastewater.

[0099] Figure 4 This is a schematic diagram of the treatment effects of different salts after electrodialysis treatment for a method of separating, recovering and resource-recovering multiple valuable substances from pharmaceutical wastewater. DETAILED DESCRIPTION

[0100] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0101] The following first describes the concepts involved in this application with reference to the accompanying drawings. It should be noted that the following description of each concept is intended only to make the content of this application easier to understand and does not limit the scope of protection of this application. At the same time, the embodiments and features in the embodiments of this application can be combined with each other unless there is a conflict. The following detailed description of this application will be made with reference to the accompanying drawings and in conjunction with the embodiments.

[0102] The electrodialysis device used in the present invention is as follows Figure 2 As shown, 1 is the electrodialysis power supply, 2 is the electrodialysis membrane stack, 3 is the membrane stack water inlet, 4 is the membrane stack water outlet, 5 is the electrode plate, 6 is the ion exchange membrane, 7 is the power line, 8 is the conduit, 9 is the discharge tank, 10 is the feed tank, 11 is the cathode liquid tank, 12 is the electrode plate positive electrode, and 13 is the electrode plate negative electrode. The schematic diagram is a specific embodiment to facilitate understanding and does not constitute a limitation of the present invention.

[0103] The principle of separating and recovering multi-component valuable substances of the present invention is as follows Figure 3 As shown, the AEM is an anion exchange membrane, the CEM is a cation exchange membrane, and the system is composed of an anode and a cathode, and includes a cation exchange membrane and an anion exchange membrane, as well as chambers separated by the ion exchange membrane. The schematic diagram is a specific embodiment to facilitate understanding and does not constitute a limitation of the present invention.

[0104] Example 1:

[0105] A method for separating, recovering and recycling multiple valuable substances from pharmaceutical wastewater, comprising:

[0106] Wastewater pretreatment: Place the filter membrane flat in the membrane mounting cavity and seal the membrane edges with sealing strips. Connect the water inlet to the wastewater source and the water outlet to the inlet of the electrodialysis system. Use pipe clamps to secure the pipe joints to form a pretreatment unit. Pharmaceutical wastewater generated in the pharmaceutical production process is passed through the pretreatment unit to remove particulate matter and suspended solids, resulting in pretreated wastewater. The wastewater contains 7,000 mg / L of thiocyanate ions, 10,000 mg / L of chloride ions, and 8,000 mg / L of acetate ions. The filter membrane is a ceramic membrane with a pore size of 0.32 μm.

[0107] Electrodialysis separation: The electrodialysis system includes an electrodialysis membrane stack, a DC voltage-regulated 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 two anion exchange membranes, three cation exchange membranes, two dilute chambers, and two concentrated chambers. Taking the anode electrode plate as the reference plane, the partition, homogeneous cation exchange membrane, partition, homogeneous anion exchange membrane, partition, homogeneous cation exchange membrane, partition, homogeneous anion exchange membrane, partition, homogeneous cation exchange membrane, partition, and finally the cathode electrode plate are stacked 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 concentrated chamber water tank for storing the separated thiocyanate solution, and a dilute chamber water tank for storing a mixed solution containing thiocyanate ions, miscellaneous salts, and organic matter; the electrode chamber water tank is stacked by The conduits are connected to both sides of the electrode plates, and a cathode liquid circulation loop is established through a circulation pump. The concentrate chamber water tank is connected to the concentrate water inlet and concentrate water outlet through a conduit, so that the concentrate water flows from the concentrate chamber water tank into the membrane stack in sequence and then flows back to the concentrate chamber water tank. The dilute chamber water tank is connected to the fresh water inlet and 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.

[0108] The corresponding solutions were added to each water tank in the device. The following were: 5L of 0.1mol / L sodium sulfate solution was added to the cathode water tank; 5L of pretreated wastewater was introduced into the concentrated water tank; and 5L of pretreated wastewater was introduced into the dilute water tank. The corresponding circulation pump for each water tank was then turned on. This was the circulation pump located on the conduit connecting each water tank to the corresponding compartment in the membrane stack. The corresponding circulation flow rate was adjusted, with the membrane stack flow rate controlled at 3L / min. The DC power supply was then turned on. Under constant voltage conditions, the voltage was controlled at 20V, and the circulation pump speed was set at 700rpm. When the conductivity stabilized, the reaction was considered to be at the end point, and the process was stopped and the power was turned off.

[0109] High-concentration: The booster pump, quartz sand filter, activated carbon filter, softening resin filter, reverse osmosis tubing, and precision filter are sequentially installed on the baseplate. Pipes are used to connect each component to ensure tight, leak-free connections. A control panel is mounted on one of the columns. Rollers are installed at the four corners of the baseplate's lower surface, and a receiving tray is installed at the bottom. Edges are provided at each end of the tray, nesting with support bars at the baseplate's ends. Protective blocks are installed around the baseplate, connected to it via sleeves and connecting rods, with springs installed between the connecting rods and sleeves. Vertical columns are fixed to the four corners of the baseplate, connected to the top frame, and retaining bars are installed between adjacent columns. A control panel is mounted on the column, and all wiring is connected. The effluent from the electrodialysis concentration chamber is introduced into the RO reverse osmosis unit. The booster pump is activated, allowing the wastewater to pass through the various filtration units and reverse osmosis tubing for high-concentration concentration, resulting in a high-concentrate solution. The reverse osmosis membrane is multi-stage, and the RO membrane elements are spiral wound elements with a separation and screening particle size of 0.45 nm and a designed membrane flux of 15 LMH.

[0110] Distillation extraction: The distillation tower is equipped with three distillation zones. The metering pump and nozzle of the extractant addition device are installed in the middle of the distillation tower. The nozzle can be adjusted in angle and direction to ensure that the extractant is evenly sprayed into the distillation zone. The reflux system connects the top and bottom of the distillation tower. The collection device is located 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. The highly concentrated liquid is introduced into the distillation extraction system and extractive distillation is carried out under normal pressure. The reflux ratio is 4, the tower top temperature is 70°C, and the tower bottom temperature is 120°C. Acetophenone is used as the extractant, and the molar ratio of extractant to raw liquid is 5:1.

[0111] Cooling crystallization: The shell is a vertical cylindrical container with multiple sets of cooling coils installed inside. Each layer of cooling coils is hexagonal and mounted on a multifunctional lifting pipe. The multifunctional lifting pipe is connected to the hydraulic lifting device on the flat cover. From top to bottom, it forms multiple individual crystallizers connected in sequence. Each crystallizer is a multi-layer polygonal cooling coil formed by winding straight tubes. The pipes between layers are connected by three-dimensional elbows and are staggered. The hydraulic lifting device consists of a rigid connecting frame, hydraulic cylinders, and hydraulic pump station. The cooling coils are connected to the cooling medium distribution pipe. The shell is equipped with a seed crystal circulation pipeline, and the distribution device, scraping device, and conical head are installed in place. The separated liquid after extraction is introduced into the cooling crystallization system, and sodium thiocyanate is obtained by cooling crystallization. The crystallizer temperature is 5°C, the stirring speed is 1000 rpm, and the wastewater residence time is 1.5 hours.

[0112] Example 2: Compared with Example 1, the only difference between this example and Example 1 is the pretreatment of wastewater.

[0113] Preparation of modified silica gel: Calcium lactobionate and α-D-mannose pentaacetate were dissolved in deionized water at room temperature and stirred evenly. Tetraethoxysilane was added, and the pH was adjusted to 3.5. The mixture was stirred at 40°C for 8 hours to form a uniform sol. The sol was aged for 48 hours, continuously solvent-exchanged with deionized water, and freeze-dried under vacuum to obtain the modified silica gel. The mass-to-volume ratio of calcium lactobionate to deionized water was 6.4 g:30 mL, the mass-to-volume ratio of α-D-mannose pentaacetate to deionized water was 6.4 g:30 mL, and the volume ratio of tetraethoxysilane to deionized water was 5:30. The stirring speed was 600 rpm.

[0114] Preparation of modified polyacrylonitrile pellets: Polyacrylonitrile was added to N,N-dimethylformamide with stirring and stirred at 50°C for 3 hours to form a uniform polyacrylonitrile solution. The polyacrylonitrile solution was then added dropwise to deionized water. After solidification, the pellets were soaked and washed with deionized water to obtain polyacrylonitrile pellets. The pellets were then immersed in a 2 mol / L sodium hydroxide solution and stirred at 60°C for 1 hour. They were then washed with deionized water and dried. The pellets were then immersed in a 1 mol / L hydrochloric acid solution and stirred for 2 hours. The pellets were then washed with deionized water and vacuum dried at 50°C for 24 hours to obtain modified polyacrylonitrile pellets. The mass ratio of polyacrylonitrile to N,N-dimethylformamide was 3:27, and the stirring speed was 600 rpm.

[0115] Preparation of composite polyacrylonitrile electrospinning solution: Disperse modified silica gel in anhydrous ethanol and sonicate for 30 minutes to form a uniform modified silica dispersion; dissolve modified polyacrylonitrile beads in N,N-dimethylformamide, stir at 50°C for 24 hours, add silver nitrate, stir for 1 hour, and sonicate for 10 minutes to obtain a modified polyacrylonitrile solution; mix the modified silica dispersion and the modified polyacrylonitrile solution, and sonicate for 30 minutes to obtain a composite polyacrylonitrile electrospinning solution. The mass volume ratio of modified silica gel to anhydrous ethanol is 3 g:6 mL; the mass ratio of modified polyacrylonitrile beads to N,N-dimethylformamide is 3:27; the mass ratio of silver nitrate to N,N-dimethylformamide is 0.2:27; the modified silica gel dispersion is measured by the mass of the modified silica gel therein, the modified polyacrylonitrile solution is measured by the mass of the modified polyacrylonitrile beads therein, and the mass ratio of modified silica gel to modified polyacrylonitrile beads is 3:3; the stirring speed is 600 rpm.

[0116] Preparation of polyacrylonitrile composite nanofiber membranes: The composite polyacrylonitrile electrospinning solution was electrospun for 5 hours to obtain an electrospun fiber membrane. The electrospun fiber membrane was then immersed in a 0.2 mol / L sodium orthovanadate aqueous solution for 1 hour, washed with deionized water, and vacuum-dried at 60°C for 24 hours to obtain the polyacrylonitrile composite nanofiber membrane. The electrospinning voltage was 18 kV, the extrusion flow rate was 1 mL / h, the spinning environment temperature was 25°C, and the relative humidity was 40%.

[0117] Wastewater pretreatment: Place the filter membrane flat in the membrane mounting cavity and seal the membrane edges with sealing strips. Connect the water inlet to the wastewater source and the water outlet to the inlet of the electrodialysis system. Use pipe clamps to secure the pipe joints to form a pretreatment unit. Secondary mother liquor generated in the pharmaceutical production process is passed through the pretreatment unit to remove particulate matter and suspended solids, resulting in pretreated wastewater. The wastewater contains 7,000 mg / L of thiocyanate ions, 10,000 mg / L of chloride ions, and 8,000 mg / L of acetate ions. The filter membrane is a polyacrylonitrile composite nanofiber membrane with a pore size of 0.32 μm.

[0118] Example 3: Compared with Example 2, this example is different only in the preparation of modified silica gel.

[0119] Preparation of the modified silica gel: Calcium lactobionate and α-D-mannose pentaacetate were dissolved in deionized water at room temperature and stirred until uniform. Tetraethoxysilane was added, and the pH was adjusted to 3.5. The mixture was stirred at 40°C for 8 hours to form a uniform sol. The sol was aged for 48 hours, continuously solvent-exchanged with deionized water, and freeze-dried under vacuum to obtain the modified silica gel. The mass-to-volume ratio of calcium lactobionate to deionized water was 6.4 g:30 mL, the mass-to-volume ratio of α-D-mannose pentaacetate to deionized water was 12.8 g:30 mL, and the volume ratio of tetraethoxysilane to deionized water was 5:30. The stirring speed was 600 rpm.

[0120] Example 4: Compared with Example 2, this example is different only in the preparation of modified silica gel.

[0121] Preparation of modified silica gel: Calcium lactobionate and α-D-mannose pentaacetate were dissolved in deionized water at room temperature and stirred until uniform. Tetraethoxysilane and aniline methyl triethoxysilane were added, and the pH was adjusted to 3.5. The mixture was stirred at 40°C for 8 hours to form a uniform sol. The sol was aged for 48 hours, continuously solvent-exchanged with deionized water, and freeze-dried under vacuum to obtain the modified silica gel. The mass-to-volume ratio of calcium lactobionate to deionized water was 6.4 g:30 mL, the mass-to-volume ratio of α-D-mannose pentaacetate to deionized water was 6.4 g:30 mL, the volume ratio of tetraethoxysilane to deionized water was 5:30, and the volume ratio of aniline methyl triethoxysilane to deionized water was 5:30. The stirring speed was 600 rpm.

[0122] Example 5: Compared with Example 4, this example is different only in the preparation of modified silica gel.

[0123] Preparation of modified silica gel: Calcium lactobionate and α-D-mannose pentaacetate were dissolved in deionized water at room temperature and stirred until uniform. Tetraethoxysilane and aniline methyl triethoxysilane were added, and the pH was adjusted to 3.5. The mixture was stirred at 40°C for 8 hours to form a uniform sol. The sol was aged for 48 hours, continuously solvent-exchanged with deionized water, and freeze-dried under vacuum to obtain the modified silica gel. The mass-to-volume ratio of calcium lactobionate to deionized water was 6.4 g:30 mL, the mass-to-volume ratio of α-D-mannose pentaacetate to deionized water was 6.4 g:30 mL, the volume ratio of tetraethoxysilane to deionized water was 5:30, and the volume ratio of aniline methyl triethoxysilane to deionized water was 10:30. The stirring speed was 600 rpm.

[0124] Comparative Example 1: This comparative example differs from Example 2 only in the preparation of the modified silica gel.

[0125] Preparation of modified silica gel: Calcium lactobionate was dissolved in deionized water at room temperature and stirred evenly. Tetraethoxysilane was added and the pH was adjusted to 3.5. The mixture was stirred at 40°C for 8 hours to form a uniform sol. The sol was aged for 48 hours, continuously solvent-exchanged with deionized water, and freeze-dried under vacuum to obtain the modified silica gel. The mass-to-volume ratio of calcium lactobionate to deionized water was 6.4 g:30 mL, and the volume ratio of tetraethoxysilane to deionized water was 5:30. The stirring speed was 600 rpm.

[0126] Comparative Example 2: This comparative example differs from Example 2 only in the preparation of the modified silica gel.

[0127] Preparation of the modified silica gel: α-D-mannose pentaacetate was dissolved in deionized water at room temperature and stirred until uniform. Tetraethoxysilane was added and the pH was adjusted to 3.5. The mixture was stirred at 40°C for 8 hours to form a uniform sol. The sol was aged for 48 hours, continuously solvent-exchanged with deionized water, and freeze-dried under vacuum to obtain the modified silica gel. The mass-to-volume ratio of α-D-mannose pentaacetate to deionized water was 6.4 g:30 mL, and the volume ratio of tetraethoxysilane to deionized water was 5:30. The stirring speed was 600 rpm.

[0128] Comparative Example 3: Compared with Example 2, this comparative example differs only in the preparation of the modified silica gel.

[0129] Preparation of modified silica gel: Tetraethoxysilane was added to deionized water at room temperature, the pH adjusted to 3.5, and the mixture was stirred at 40°C for 8 hours to form a uniform sol. The sol was aged for 48 hours, continuously solvent-exchanged with deionized water, and freeze-dried under vacuum to obtain the modified silica gel. The volume ratio of tetraethoxysilane to deionized water was 5:30, and the stirring speed was 600 rpm.

[0130] Test Example 1: Treatment effect test of actual pharmaceutical wastewater with different salt contents after electrodialysis treatment.

[0131] Test sample: the effluent from the concentrate chamber after electrodialysis treatment in Example 1.

[0132] Test method: After the start of the electrodialysis reaction, water samples were collected from the outlet of the concentration chamber every 15 minutes for 60 minutes; thiocyanate ions were complexed with iron ions and measured by UV spectrophotometry, and the separation efficiency and selectivity were evaluated based on the thiocyanate ion concentration; the ion concentration changes of chloride ions and acetate ions were detected based on ion chromatography.

[0133] The results of the treatment effects of different salt contents of actual industrial wastewater after electrodialysis treatment are as follows: Figure 4As shown, it shows that the electrodialysis system has a good separation and concentration effect on thiocyanate ions, chloride ions and acetate ions in wastewater, and can effectively reduce the content of related ions and organic matter in the wastewater of the freshwater room.

[0134] Experimental Example 2: Antibiotic adsorption test of polyacrylonitrile composite nanofiber membrane.

[0135] Test samples: polyacrylonitrile composite nanofiber membranes prepared in Examples 2-5 and Comparative Examples 1-3.

[0136] Test method: Cut the polyacrylonitrile composite nanofiber membrane into samples of the same size and mass and immerse them completely in a solution with a concentration of C 0 tetracycline solution, after light protection, shake and adsorb at 25 ° C for 4 hours, the shaking speed is 130 rpm, and the supernatant is taken after filtration and the absorbance is measured by UV spectrophotometer to calculate the tetracycline concentration after the adsorption time. C t .

[0137] The adsorption removal rate of tetracycline by polyacrylonitrile composite nanofiber membrane is calculated as follows:

[0138]

[0139] Where:

[0140] R is the adsorption removal rate, C 0 is the initial tetracycline concentration, C t is the tetracycline concentration after adsorption time.

[0141] The antibiotic adsorption test results of the polyacrylonitrile composite nanofiber membrane prepared in the present invention are shown in Table 1:

[0142] Table 1 Antibiotic adsorption test results of polyacrylonitrile composite nanofiber membrane

[0143]

[0144] Compared with Example 2, Example 3 adjusts the ratio of pentaacetic acid α-D-mannose in the modified silica gel to make tetracycline easier to enter the membrane and be adsorbed; Example 4 introduces aniline methyl triethoxysilane to prepare modified silica gel, in which the amino and ethoxysilane groups can interact with the polyacrylonitrile molecular chains to form a more complex network structure, thereby enhancing the adsorption capacity of tetracycline; Example 5 increases the amount of aniline methyl triethoxysilane to further strengthen the interaction, making the network structure of the membrane more compact and orderly, thereby significantly improving the adsorption capacity. Adsorption removal rate; Comparative Example 1 uses only calcium lactobionate to prepare the modified silica gel, lacks α-D-mannose pentaacetate, and Comparative Example 2 lacks calcium lactobionate, and the adsorption removal rate is much lower than that of Example 2; Comparative Example 3 does not use these two substances, and the adsorption removal rate is the lowest, indicating that calcium lactobionate and α-D-mannose pentaacetate play a key role in the preparation of the membrane, participate in the sol-gel process, affect the microstructure of the modified silica gel, and thus lead to an unreasonable pore structure of the membrane, so that the adsorption removal rate is much lower than that of the embodiment, reflecting its poor adsorption capacity for tetracycline.

[0145] Test Example 3: Volatile organic compound separation test of polyacrylonitrile composite nanofiber membrane.

[0146] Test samples: polyacrylonitrile composite nanofiber membranes prepared in Examples 2-5 and Comparative Examples 1-3.

[0147] Test method: Cut the polyacrylonitrile composite nanofiber membrane into samples of the same size and mass, and filter 50 mL of the sample with a concentration of 0.3 L / min at a N2 flow rate of 0.3 L / min. C 0 toluene solution, and the fluorescence intensity was measured by fluorescence spectrophotometer to calculate the concentration of toluene after filtration. C t .

[0148] The retention rate of toluene by polyacrylonitrile composite nanofiber membrane is calculated as follows:

[0149]

[0150] Where:

[0151] R is the retention rate, C 0 is the initial toluene concentration, C t is the toluene concentration after adsorption time.

[0152] The volatile organic compound separation test results of the polyacrylonitrile composite nanofiber membrane prepared in the present invention are shown in Table 2:

[0153] Table 2 Volatile organic compound separation test results of polyacrylonitrile composite nanofiber membrane

[0154]

[0155] Compared with Comparative Examples 1-2, the toluene retention rate of Example 2 is significantly improved, indicating that the polyacrylonitrile composite nanofiber membrane prepared in Example 2 has better performance, a more uniform and suitable pore size distribution, and can effectively intercept volatile organic compounds such as toluene in wastewater during wastewater pretreatment. Example 3 increases the amount of α-D-mannose pentaacetate, so that the polyacrylonitrile composite nanofiber membrane has better mechanical strength and stability, and can continuously and stably exert a filtering effect. Compared with Example 2, the toluene retention rate is also improved. In Example 4, aniline methyl triethoxysilane is introduced into the preparation of modified silica gel, so that the membrane pore size can more accurately block impurities without affecting the passage of ions, thereby improving the toluene retention rate. Example 5 further improves the toluene retention rate by adjusting the amount of aniline methyl triethoxysilane. In Comparative Example 1-2, only one of calcium lactobionate and α-D-mannose pentaacetate was used, and the toluene retention rate was greatly reduced. In Comparative Example 3, neither calcium lactobionate nor α-D-mannose pentaacetate was used, and the toluene retention rate was the lowest. This shows that calcium lactobionate and α-D-mannose pentaacetate have an important influence on the preparation of the membrane, and work synergistically to improve the performance of the pre-filtration membrane, which is of key significance for improving the efficiency of the entire wastewater treatment system.

[0156] 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 do not impose any form of limitation on the implementation methods of the technology of the present invention. Any person skilled in the art 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.

[0157] 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 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, there are objectively infinite specific structures. For ordinary technicians in this technical field, without departing from the principles of this application, they can also make several improvements, modifications or changes, and can also combine the above technical features in an appropriate manner; these improvements, modifications, changes or combinations, or the direct application of the inventive concept and technical solution to other occasions without improvement, should be regarded as the scope of protection of this application.

Claims

1. A method for separating, recovering and recycling multiple valuable substances from pharmaceutical wastewater, comprising: Pre-treating pharmaceutical wastewater through a pre-treatment unit to remove particulate matter and obtain pre-treated wastewater; The pretreated wastewater is introduced into the electrodialysis system to achieve preliminary separation and concentration to obtain separated fresh water and concentrated water; The concentrated water is introduced into the RO reverse osmosis system for high-multiple concentration to obtain a concentrated solution; the concentrated solution is distilled to obtain glacial acetic acid and a separation solution; The separated liquid is further separated into thiocyanate ions, chloride ions and acetate ions by cooling crystallization, and the thiocyanate ions, chloride ions and acetate ions are used together for the front-end production; or, Adjust the pH of fresh water, intercept glacial acetic acid, and introduce the separated glacial acetic acid into the biological system as a carbon source for biological treatment; the concentrated water is introduced into the electrodialysis concentration system and RO reverse osmosis system, and after concentration and crystallization, the thiocyanate ion and chloride ion are separated, and after concentration adjustment, they can be reused in the front-end process or purified for sale.

2. A method for separating, recovering and recycling multiple valuable substances from pharmaceutical wastewater according to claim 1, wherein the pretreatment unit includes a microfiltration and ultrafiltration system, the filtration mode includes an immersion type, an MBR membrane pool type or a vibrating membrane type, the filter membrane pore size is 0.2-100 μm, and the filter membrane includes a polyacrylonitrile composite nanofiber membrane, a hollow fiber membrane, a polysulfone membrane, a polyamide membrane or a ceramic membrane.

3. The method for separating, recovering and recycling multiple valuable substances from pharmaceutical wastewater according to claim 2, wherein the steps of preparing the polyacrylonitrile composite nanofiber membrane include: Calcium lactobionate and α-D-mannose pentaacetate are dissolved in deionized water, tetraethoxysilane is added, and the mixture is stirred to react to form a sol, which is then aged, solvent exchanged, and freeze-dried in vacuo to obtain a modified silica gel. Polyacrylonitrile was dissolved in N,N-dimethylformamide to form a uniform solution, deionized water was added to solidify it into balls, and then modified with sodium hydroxide solution and hydrochloric acid solution, and then washed and dried to obtain modified polyacrylonitrile balls. The modified silica gel is dispersed in anhydrous ethanol to obtain a modified silica dispersion, modified polyacrylonitrile beads are dissolved in N,N-dimethylformamide, silver nitrate is added to obtain a modified polyacrylonitrile solution, the modified silica dispersion and the modified polyacrylonitrile solution are mixed and sonicated to obtain a composite polyacrylonitrile electrospinning solution; The composite polyacrylonitrile electrospinning solution is subjected to electrostatic spinning, modified with a sodium orthovanadate solution, and washed and dried to obtain a polyacrylonitrile composite nanofiber membrane.

4. The method for separating, recovering and recycling multiple valuable substances from pharmaceutical wastewater according to claim 3, wherein the mass volume ratio of calcium lactobionate to deionized water is 3.2-12.8 g:15-60 mL, the mass volume ratio of α-D-mannose pentaacetate to deionized water is 3.2-12.8 g:15-60 mL, and the volume ratio of tetraethoxysilane to deionized water is 2.5-10:15-60.

5. The method for separating, recovering, and recycling multiple valuable substances from pharmaceutical wastewater according to claim 3, wherein the modified silica gel dispersion is measured by the mass of the modified silica gel therein, and the modified polyacrylonitrile solution is measured by the mass of the modified polyacrylonitrile beads therein, and the mass ratio of the modified silica gel to the modified polyacrylonitrile beads is 1-6:1-6.

6. A method for separating, recovering and resource-recycling multiple valuable substances from pharmaceutical wastewater according to claim 1, wherein the electrodialysis system is composed of an electrodialysis membrane stack, a DC regulated power supply, a flow meter, 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 constitute the anode chamber, the cathode plate and the adjacent partition constitute the cathode chamber, and at least one membrane unit is provided between the anode chamber and the cathode chamber; a plurality of ion exchange membranes are provided in the membrane unit, and a concentrated chamber or a dilute chamber is formed between the two ion exchange membranes, and the concentrated chamber and the dilute chamber are freely combined according to the target ion recovery principle and efficiency optimization; the water tank includes a pole chamber water tank for storing the pole 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, miscellaneous salts and organic matter.

7. A method for separating, recovering and recycling multiple valuable substances from pharmaceutical wastewater according to claim 6, wherein the solute in the polar chamber water tank polar liquid is one or more of sodium sulfate, sodium chloride and sodium nitrate, and the solute concentration is 0.05-0.2 mol / L; the number of 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 a heterogeneous membrane, a homogeneous membrane and an 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.

8. A method for separating, recovering and recycling multiple valuable substances from pharmaceutical wastewater according to claim 1, wherein the RO reverse osmosis includes a single-stage or multi-stage type, the RO membrane element adopts a spiral membrane element, the particle size of the separation and screening is 0.1-0.9 nm, and the designed membrane flux is 10-20LMH.

9. A method for separating, recovering and recycling multiple valuable substances from pharmaceutical wastewater according to claim 1, wherein the distillation is one of batch distillation, continuous distillation, extractive distillation and azeotropic distillation; the extractive distillation is operated at normal pressure, with a reflux ratio of 1-8, a tower top temperature of 60-80°C, a tower bottom temperature of 110-130°C, and a molar ratio of the extractant to the raw material liquid of 1-10:10-100; and the extractant is one or more of acetophenone, N-methylacetamide, methyl pyrrolidone, tributyl phosphate and isopropyl acetate.

10. The method for separating, recovering and recycling multiple valuable substances from pharmaceutical wastewater according to claim 1, wherein the cooling crystallization is performed by optimizing the crystallizer temperature of 0-20°C, the stirring speed of 500-3000 rpm, and the wastewater residence time of 0.5-3 hours to control the optimal crystallization conditions.

Images