Method for separating, recycling and recycling various valuable substances from pharmaceutical wastewater

Abstract

The invention relates to a method for separating, recycling and recycling various valuable substances from pharmaceutical wastewater. Thiocyanate ions, chloride ions and acetate ions are separated and recycled from the pharmaceutical wastewater by adopting an integrated technology based on electrodialysis. The method is characterized by comprising the following steps: firstly, pretreating the pharmaceutical wastewater by virtue of a polyacrylonitrile composite nanofiber membrane to remove large-particle substances in the wastewater; introducing the treated wastewater into an electrodialysis system to realize separation of salt and organic matters in the wastewater; introducing the separated fresh water into a biological system for biological treatment, and introducing concentrated water into an electrodialysis concentration system; concentrated water obtained after primary concentration is introduced into an RO reverse osmosis system for high-multiple concentration, and high-multiple concentration, separation and recovery of multi-component salt are achieved. According to the method, the problem of separation and recovery of valuable salt molecules in the pharmaceutical wastewater is solved, sufficient resource utilization of salt is achieved, pollution-free emission is achieved in the whole technological process, and zero-approaching emission of industrial wastewater is promoted.

Description

Technical Field

[0001] The 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 global climate change and environmental problems, the green transformation of industry and the new development mode of green low-carbon cycle 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. At present, the mainstream treatment methods for industrial wastewater, such as physical, biological and chemical methods, mostly directly eliminate or remove the 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, it has the functions of acidification and antiseptic. It can also be used in the dye industry, pharmaceutical industry and other fields.

[0003] For the treatment of thiocyanate and acetate, the industry's 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 leads to low purity of ions after separation and recovery, causing great 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 object 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 solution adopted by the present invention to achieve the above-mentioned purpose is: A method for separating, recovering and recycling a variety of 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; Introduce concentrated water into RO reverse osmosis system for high multiple concentration; distill the concentrated liquid to obtain glacial acetic acid and separation liquid; further separate the separation liquid into thiocyanate ion, chloride ion and acetate ion by cooling crystallization, and use them together for 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; introduce the concentrated water into the electrodialysis concentration system and RO reverse osmosis system, and separate the thiocyanate ions and chloride ions through concentration and crystallization. After concentration adjustment, they can be reused in the front-end process or purified for sale.

[0007] Preferably, the pre-treatment unit comprises a microfiltration and an ultrafiltration system.

[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 comprises a polyacrylonitrile composite nanofiber membrane, a hollow fiber membrane, a polysulfone membrane, a polyamide membrane or a ceramic membrane.

[0011] The preparation steps of the polyacrylonitrile composite nanofiber membrane include: Calcium lactobionate and α-D-mannose pentaacetate are dissolved in deionized water, tetraethoxysilane is added, stirred to react to form a sol, and then aged, solvent exchanged, and vacuum-freeze-dried to obtain a modified silica gel; Polyacrylonitrile is dissolved in N,N-dimethylformamide to form a uniform solution, deionized water is 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, the 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 ultrasonicated 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.

[0012] Calcium lactobionate and α-D-mannose pentaacetate were introduced into the formation of modified silica gel, which enhanced the cross-linking degree of the gel network and made the generated polyacrylonitrile composite nanofiber membrane have a stable microstructure within the membrane. The stability of the polyacrylonitrile composite nanofiber membrane was improved, and the membrane could continuously and stably play a filtering role in a complex pharmaceutical wastewater environment, so that the quality of wastewater entering the electrodialysis system was stable, and the efficiency of subsequent separation, concentration and other steps was improved. The adsorption performance of the polyacrylonitrile composite nanofiber membrane on pollutants in pharmaceutical wastewater was improved, the adsorption removal rate and the interception rate were improved, and the efficiency of the entire wastewater treatment system was improved.

[0013] 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 produced by the hydrolysis of tetraethoxysilane, and further enhance the cross-linking degree of the gel network through hydrogen bond interactions 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.

[0014] Preferably, the mass volume ratio of calcium lactobionate to deionized water is 3.2-12.8 g:15-60 mL.

[0015] Preferably, the mass volume ratio of α-D-mannose pentaacetate to deionized water is 3.2-12.8 g:15-60 mL.

[0016] Preferably, the volume ratio of tetraethoxysilane to deionized water is 2.5-10:15-60.

[0017] More preferably, aniline methyl triethoxysilane can be added in the preparation of modified silica gel, and the volume ratio of aniline methyl triethoxysilane to deionized water is 2.5-10:15-60. This makes the overall structure of the generated polyacrylonitrile composite nanofiber membrane more stable, and can better withstand changes in pressure and chemical environment during the subsequent treatment of pharmaceutical wastewater, and is not easily deformed or damaged; 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, and improves the subsequent electrodialysis system's separation effect on salt and organic matter in pharmaceutical wastewater.

[0018] 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.

[0019] The electrodialysis system 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 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 and impurities and organic matter.

[0020] 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.

[0021] Preferably, the number of membrane units is 1-50.

[0022] Preferably, the electrodialysis membrane stack voltage is 5-50V, and the electrodialysis membrane stack flow rate is 1000-10000mL / min.

[0023] 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.

[0024] Preferably, the RO reverse osmosis comprises a single-stage type or a multi-stage type.

[0025] Preferably, the RO membrane element is a spiral membrane element.

[0026] Preferably, the particle size of the separation and screening is 0.1-0.9 nm, and the designed membrane flux is 10-20 LMH.

[0027] Preferably, the distillation can be carried out by batch distillation, continuous distillation, extractive distillation and azeotropic distillation.

[0028] Preferably, the extractive distillation is operated at normal pressure with a reflux ratio of 1-8.

[0029] Preferably, the tower top temperature is 60-80°C.

[0030] Preferably, the bottom temperature is 110-130°C.

[0031] Preferably, the molar ratio of the extractant to the raw material liquid is 1-10:10-100.

[0032] Preferably, the extractant includes acetophenone, N-methylacetamide, methyl pyrrolidone, tributyl phosphate, and isopropyl acetate.

[0033] Preferably, cooling crystallization controls the optimal crystallization conditions by optimizing the crystallizer temperature of 0-20°C, the stirring speed of 500-3000rpm, and the wastewater residence time of 0.5-3h.

[0034] The present invention also provides a method for separating, recovering and recycling a variety of valuable substances from pharmaceutical wastewater, comprising: Pretreatment of wastewater: Place the filter membrane flat into 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 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 matter to obtain pretreated wastewater.

[0035] Preferably, the filtration mode includes immersion type, MBR membrane pool type or vibrating membrane type.

[0036] Preferably, the filter membrane material includes hollow fiber, polysulfone, polyamide or ceramic.

[0037] Preferably, the pore size of the filter membrane is 0.2-100 μm.

[0038] Electrodialysis separation: The electrodialysis system 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 membrane stack are positive electrode plates and negative electrode plates; the anode plate and the adjacent partition form an anode chamber, and the cathode plate and the adjacent partition form a cathode chamber. A membrane unit is provided between the anode chamber and the cathode chamber. When the membrane unit is repeated, the multiple membrane units are arranged closely together; multiple ion exchange membranes are provided in the membrane unit, and the ion exchange membranes include cation exchange membranes and anion exchange membranes. A concentrated chamber or a dilute chamber is formed between the two ion exchange membranes. 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-diluted, dilute-dilute-concentrated, concentrated-concentrated-concentrated-diluted, 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 pole chamber water tank for storing pole liquid, a concentration 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 pole chamber water tank is connected to both sides of the electrode plate through a conduit, and a pole liquid circulation loop is established through a circulating pump; the concentration chamber water tank 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 in sequence into the membrane stack and then flows back to the concentration chamber water tank; the dilute chamber water tank is connected to the dilute water inlet and the 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. The corresponding solutions are added to each water tank of the device, wherein: the pole liquid is added to the pole chamber water tank; the concentrated chamber water tank is connected to pure water; and the dilute chamber water tank is connected to pretreated wastewater. Then, the circulation pump corresponding to each water tank is turned on, that is, the circulation pump set on the conduit connecting each water tank and the corresponding compartment in the membrane stack is turned on, and the corresponding circulation flow rate is adjusted. Then the DC power supply is turned on, and when the conductivity is observed to be stable, it is regarded as the end point of the reaction, and the treatment is stopped and the power supply is turned off.

[0039] Preferably, the number of membrane units is 1-50.

[0040] More preferably, the number of membrane units is 5-20.

[0041] 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.

[0042] 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.

[0043] More preferably, the solute is sodium sulfate with a concentration of 0.05-0.1 mol / L.

[0044] Preferably, the volume of the cathode chamber water tank, the concentration chamber water tank, and the dilution chamber water tank are all 5L.

[0045] Preferably, the electrodialysis membrane stack voltage is 5-50V, and the electrodialysis membrane stack flow rate is 1000-10000mL / min.

[0046] Preferably, the rotation speed of the circulation pump is maintained at 600-800 rpm.

[0047] 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 bottom plate in sequence, and 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 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 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, 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.

[0048] Preferably, the reverse osmosis membrane adopts a single-stage or multi-stage type.

[0049] Preferably, the RO membrane element is a spiral membrane element.

[0050] Preferably, the particle size of the separation and screening is 0.1-0.9 nm, and the designed membrane flux is 10-20 LMH.

[0051] Distillation extraction: The distillation tower is provided with a distillation zone, and 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 is connected to the top and bottom of the distillation tower; the collecting device is arranged 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-concentrated liquid of RO reverse osmosis is introduced into the distillation extraction system, and the extractive distillation is carried out under normal pressure; the mixture of the extractant and water is distilled through a pipeline to the water distillation kettle, the extractant is recovered, and the high-purity glacial acetic acid is collected.

[0052] Preferably, the reflux ratio is controlled to be 1-8.

[0053] Preferably, the tower top temperature is 60-80°C, and the tower bottom temperature is 110-130°C.

[0054] Preferably, the molar ratio of the extractant to the raw material liquid is 1-10:10-100.

[0055] Preferably, the extractant includes acetophenone, monomethylacetamide, methyl pyrrolidone, tributyl phosphate, and isopropyl acetate.

[0056] Cooling crystallization: install a vertical cylindrical container-shaped shell, install cooling coils in the shell, connect the cooling coils with the cooling medium distribution pipe, make each layer of cooling coils hexagonal and fixed on the multifunctional lifting pipe; install a flat cover on the top of the shell, install a material distribution device; install a conical head and a scraper 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 circulation pipeline outside the shell; introduce the separated liquid after extraction into the cooling crystallization system, and obtain sodium thiocyanate by cooling crystallization.

[0057] Preferably, the crystallizer temperature is controlled at 0-20°C and the stirring speed is controlled at 500-3000 rpm.

[0058] More preferably, the crystallizer temperature is controlled at 0-10°C and the stirring speed is controlled at 500-2000 rpm.

[0059] Preferably, the wastewater retention time is 1-2 hours.

[0060] The present invention also provides a method for preparing a polyacrylonitrile composite nanofiber membrane, comprising: 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, and the solvent is continuously exchanged with deionized water, and vacuum freeze-dried to obtain modified silica gel.

[0061] Preferably, the mass volume ratio of calcium lactobionate to deionized water is 3.2-12.8 g:15-60 mL.

[0062] Preferably, the mass volume ratio of α-D-mannose pentaacetate to deionized water is 3.2-12.8 g:15-60 mL.

[0063] Preferably, the volume ratio of tetraethoxysilane to deionized water is 2.5-10:15-60.

[0064] Preferably, the stirring speed is 500-700 rpm.

[0065] 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 1.5-2.5mol / L sodium hydroxide solution, stir at 55-65°C for 0.5-1.5h, wash and dry with deionized water, then immerse in 0.5-1.5mol / L hydrochloric acid solution, stir for 1-3h, wash with deionized water, and vacuum dry at 45-55°C for 20-30h to obtain modified polyacrylonitrile beads.

[0066] Preferably, the mass ratio of polyacrylonitrile to N,N-dimethylformamide is 1-6:9-54.

[0067] Preferably, the stirring speed is 500-700 rpm.

[0068] Preparation of composite polyacrylonitrile electrospinning solution: Disperse modified silica gel in anhydrous ethanol, and ultrasonicate for 15-45 minutes to form a uniform modified silica dispersion; dissolve modified polyacrylonitrile beads in N,N-dimethylformamide, stir for 20-30 hours at 45-55°C, add silver nitrate, stir for 0.5-1.5 hours, and ultrasonicate for 5-15 minutes to obtain a modified polyacrylonitrile solution; mix the modified silica dispersion with the modified polyacrylonitrile solution, and ultrasonicate for 20-40 minutes to obtain a composite polyacrylonitrile electrospinning solution.

[0069] Preferably, the mass volume ratio of modified silica gel to anhydrous ethanol is 1-6 g:2-12 mL.

[0070] Preferably, the mass ratio of modified polyacrylonitrile beads to N,N-dimethylformamide is 1-6:9-54.

[0071] Preferably, the mass ratio of silver nitrate to N,N-dimethylformamide is 0.1-0.4:13.5-54.

[0072] 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.

[0073] Preferably, the stirring speed is 500-700 rpm.

[0074] 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.

[0075] Preferably, the electrospinning voltage is 16-20 kV and the extrusion flow rate is 0.8-1.2 mL / h.

[0076] Preferably, the spinning environment temperature is 23-27° C., and the relative humidity is 20-60%.

[0077] The present invention also provides a method for preparing modified silica gel, comprising: 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, and the solvent is continuously exchanged with deionized water, and vacuum freeze-dried to obtain modified silica gel.

[0078] Preferably, the mass volume ratio of calcium lactobionate to deionized water is 3.2-12.8 g:15-60 mL.

[0079] Preferably, the mass volume ratio of α-D-mannose pentaacetate to deionized water is 3.2-12.8 g:15-60 mL.

[0080] Preferably, the volume ratio of tetraethoxysilane to deionized water is 2.5-10:15-60.

[0081] Preferably, the volume ratio of aniline methyl triethoxysilane to deionized water is 2.5-10:15-60 Preferably, the stirring speed is 500-700 rpm.

[0082] The present invention uses a polyacrylonitrile composite nanofiber membrane to pre-treat pharmaceutical wastewater, introduces the pre-treated wastewater into an electrodialysis system, an RO reverse osmosis system, a distillation extraction system, and a cooling crystallization system, and realizes separation, recovery, and resource utilization of multiple valuable substances from pharmaceutical wastewater, thereby having the following beneficial effects: high concentration efficiency and good separation effect of multi-component valuable substances, and separation and recovery of salts for reuse in the production process section. Therefore, the present invention is an efficient, pollution-free method for separation, recovery, and resource utilization of multiple valuable substances from pharmaceutical wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] Figure 1 The present invention is a process flow diagram of a method for separating, recovering and recycling a variety of valuable substances from pharmaceutical wastewater.

[0084] Figure 2 The present invention is a schematic diagram of the structure of an electrodialysis device provided in a method for separating, recovering and recycling a variety of valuable substances from pharmaceutical wastewater.

[0085] 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.

[0086] Figure 4 This is a schematic diagram of the treatment effects of different salts after electrodialysis treatment, showing a method for separating, recovering and recycling a variety of valuable substances from pharmaceutical wastewater. DETAILED DESCRIPTION

[0087] 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.

[0088] 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.

[0089] The 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.

[0090] The principle of separating and recovering multi-component valuable substances of the present invention is as follows: Figure 3 As shown, AEM is an anion exchange membrane, CEM is a cation exchange membrane, and it is composed of an anode and a cathode, and includes a cation exchange membrane and an anion exchange membrane, and a chamber separated by an ion exchange membrane. The schematic diagram is a certain implementation method to help understanding, and does not constitute a limitation of the present invention.

[0091] Embodiment 1: A method for separating, recovering and recycling a variety of valuable substances from pharmaceutical wastewater, comprising: Pretreatment of wastewater: 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 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 to form a pretreatment unit; take the pharmaceutical wastewater generated in the production process of the pharmaceutical enterprise, remove particulate matter and suspended matter through the pretreatment unit, and obtain pretreated wastewater. The wastewater contains 7000mg / L of thiocyanate ions, 10000mg / L of chloride ions, and 8000mg / L of acetate ions; the filter membrane is a ceramic membrane with a pore size of 0.32μm.

[0092] Electrodialysis separation: The electrodialysis system includes an electrodialysis membrane stack, a DC 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 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 cover the cathode plate 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 and impurities and organic matter; the electrode chamber water tank is stacked through The conduit is connected to both sides of the electrode plate, and a polar liquid circulation loop is established through a circulation pump; the concentrated water tank is connected to the concentrated water inlet and the concentrated water outlet through a conduit, so that the concentrated water flows from the concentrated water tank to the membrane stack in sequence and then flows back to the concentrated water tank; the dilute water tank is connected to the fresh water inlet and the fresh water outlet through a conduit, so that the mixed solution flows from the dilute water tank to the membrane stack in sequence and then flows back to the dilute 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, and the membrane resistance is 8Ω / cm 2 , the exchange capacity is 1.5mol / Kg, and the acidity and alkalinity resistance is pH2-10.

[0093] 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; pass 5L of pretreated wastewater into the concentrated chamber water tank; pass 5L of pretreated wastewater into 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.

[0094] High concentration: Install the booster pump, quartz sand filter, activated carbon filter, softening resin filter, reverse osmosis tube and precision filter on the bottom plate in sequence, connect the components with pipes to ensure tight connection and no leakage, and install a control panel on one of the columns; install rollers at the four corners of the lower surface of the bottom plate, install a receiving tray at the bottom, and set edge plates at both ends of the receiving tray to nest with the support strips at both ends of the bottom of the bottom plate; install protective blocks around the bottom plate, connect it to the bottom plate through sleeves and connecting rods, and install springs between the connecting rods and sleeves; vertically fix the columns at the four corners of the bottom plate, connect the top frame at the top, and install baffles between adjacent columns; install the control panel on the column and connect the circuits of each component; introduce the effluent from the electrodialysis concentration chamber into the RO reverse osmosis device, turn on the booster pump, and make the wastewater pass through each filter device and reverse osmosis tube in sequence for high concentration to obtain high-concentrate liquid. 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.

[0095] Distillation extraction: 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 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-concentrated liquid is introduced into the distillation extraction system for extraction distillation under normal pressure. The reflux ratio is 4, the tower top temperature is 70℃, and the tower bottom temperature is 120℃. Acetophenone is selected as the extractant, and the molar ratio of the extractant to the raw material liquid is 5:1.

[0096] Cooling crystallization: The shell is a vertical cylindrical container, with multiple groups of cooling coils inside. Each layer of cooling coils is hexagonal and set 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 set outside the shell. The material distribution device, scraper 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 1000rpm, and the wastewater retention time is 1.5h.

[0097] Embodiment 2: Compared with Embodiment 1, the difference between this embodiment and Embodiment 1 is only the pretreatment of wastewater.

[0098] Preparation of modified silica gel: At room temperature, calcium lactobionate and α-D-mannose pentaacetate were dissolved in deionized water, stirred evenly, tetraethoxysilane was added, the pH was adjusted to 3.5, and the mixture was reacted at 40°C and stirred for 8 hours to form a uniform sol; the sol was aged for 48 hours, and the solvent was continuously exchanged with deionized water, and the modified silica gel was obtained by vacuum freeze-drying. The mass volume ratio of calcium lactobionate to deionized water was 6.4 g:30 mL, the mass 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 stirring speed was 600 rpm.

[0099] Preparation of modified polyacrylonitrile beads: Add polyacrylonitrile to N,N-dimethylformamide under stirring conditions, stir at 50°C for 3 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 2mol / L sodium hydroxide solution, stir at 60°C for 1 hour, wash with deionized water, dry, immerse in 1mol / L hydrochloric acid solution, stir for 2 hours, wash with deionized water, and vacuum dry at 50°C for 24 hours to obtain modified polyacrylonitrile beads. The mass ratio of polyacrylonitrile to N,N-dimethylformamide is 3:27, and the stirring speed is 600rpm.

[0100] Preparation of composite polyacrylonitrile electrospinning solution: disperse modified silica gel in anhydrous ethanol and ultrasonicate 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 ultrasonicate for 10 minutes to obtain a modified polyacrylonitrile solution; mix the modified silica dispersion with the modified polyacrylonitrile solution, and ultrasonicate for 30 minutes to obtain a composite polyacrylonitrile electrospinning solution. The mass volume ratio of modified silica gel to anhydrous ethanol is 3g:6mL; 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 600rpm.

[0101] Preparation of polyacrylonitrile composite nanofiber membrane: The composite polyacrylonitrile electrospinning solution was electrospun for 5 hours to obtain an electrospun fiber membrane; the electrospun fiber membrane was soaked 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 a 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%.

[0102] Pretreatment of wastewater: 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 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 to form a pretreatment unit; take the secondary mother liquor produced in the production process of the pharmaceutical company, remove particulate matter and suspended matter through the pretreatment unit to obtain pretreated wastewater. The wastewater contains 7000mg / L of thiocyanate ions, 10000mg / L of chloride ions, and 8000mg / L of acetate ions; the filter membrane is a polyacrylonitrile composite nanofiber membrane with a pore size of 0.32μm.

[0103] Example 3: Compared with Example 2, the only difference between this example and Example 2 is the preparation of modified silica gel.

[0104] Preparation of modified silica gel: At room temperature, calcium lactobionate and α-D-mannose pentaacetate were dissolved in deionized water, stirred evenly, tetraethoxysilane was added, the pH was adjusted to 3.5, and the mixture was reacted at 40°C with stirring for 8 hours to form a uniform sol; the sol was aged for 48 hours, and the solvent was continuously exchanged with deionized water, and the modified silica gel was obtained by vacuum freeze-drying. The mass volume ratio of calcium lactobionate to deionized water was 6.4 g:30 mL, the mass volume ratio of α-D-mannose pentaacetate to deionized water was 12.8 g:30 mL, the volume ratio of tetraethoxysilane to deionized water was 5:30, and the stirring speed was 600 rpm.

[0105] Example 4: Compared with Example 2, the only difference between this example and Example 2 is the preparation of modified silica gel.

[0106] Preparation of modified silica gel: At room temperature, calcium lactobionate and α-D-mannose pentaacetate are dissolved in deionized water, stirred evenly, tetraethoxysilane and methyltriethoxysilane are added, the pH is adjusted to 3.5, and the mixture is reacted at 40°C and stirred for 8 hours to form a uniform sol; the sol is aged for 48 hours, and the solvent is continuously exchanged with deionized water, and the mixture is freeze-dried in vacuum to obtain modified silica gel. The mass volume ratio of calcium lactobionate to deionized water is 6.4 g:30 mL, the mass volume ratio of α-D-mannose pentaacetate to deionized water is 6.4 g:30 mL, the volume ratio of tetraethoxysilane to deionized water is 5:30, and the volume ratio of methyltriethoxysilane to deionized water is 5:30, and the stirring speed is 600 rpm.

[0107] Example 5: Compared with Example 4, the only difference between this example and Example 4 is the preparation of modified silica gel.

[0108] Preparation of modified silica gel: At room temperature, calcium lactobionate and α-D-mannose pentaacetate are dissolved in deionized water, stirred evenly, tetraethoxysilane and methyltriethoxyaniline are added, the pH is adjusted to 3.5, and the reaction is carried out at 40°C and stirred for 8 hours to form a uniform sol; the sol is aged for 48 hours, and the solvent is continuously exchanged with deionized water, and vacuum freeze-dried to obtain modified silica gel. The mass volume ratio of calcium lactobionate to deionized water is 6.4g:30mL, the mass volume ratio of α-D-mannose pentaacetate to deionized water is 6.4g:30mL, the volume ratio of tetraethoxysilane to deionized water is 5:30, the volume ratio of methyltriethoxyaniline to deionized water is 10:30, and the stirring speed is 600rpm.

[0109] Comparative Example 1: This comparative example is different from Example 2 only in the preparation of the modified silica gel.

[0110] Preparation of modified silica gel: At room temperature, calcium lactobionate was dissolved in deionized water, stirred evenly, tetraethoxysilane was added, the pH was adjusted to 3.5, and the mixture was reacted at 40°C and stirred for 8 hours to form a uniform sol; the sol was aged for 48 hours, and the solvent was continuously exchanged with deionized water, and vacuum freeze-dried to obtain modified silica gel. The mass volume ratio of calcium lactobionate to deionized water was 6.4 g:30 mL, the volume ratio of tetraethoxysilane to deionized water was 5:30, and the stirring speed was 600 rpm.

[0111] Comparative Example 2: This comparative example is different from Example 2 only in the preparation of the modified silica gel.

[0112] Preparation of modified silica gel: At room temperature, dissolve α-D-mannose pentaacetate in deionized water, stir evenly, add tetraethoxysilane, adjust the pH to 3.5, react at 40°C and stirring for 8 hours to form a uniform sol; age the sol for 48 hours, perform continuous solvent exchange with deionized water, and vacuum freeze-dry to obtain modified silica gel. The mass volume ratio of α-D-mannose pentaacetate to deionized water is 6.4g:30mL, the volume ratio of tetraethoxysilane to deionized water is 5:30, and the stirring speed is 600rpm.

[0113] Comparative Example 3: Compared with Example 2, this comparative example differs only in the preparation of the modified silica gel.

[0114] Preparation of modified silica gel: Add tetraethoxysilane to deionized water at room temperature, adjust the pH to 3.5, react at 40°C and stir for 8 hours to form a uniform sol; age the sol for 48 hours, perform continuous solvent exchange with deionized water, and vacuum freeze-dry to obtain modified silica gel. The volume ratio of tetraethoxysilane to deionized water is 5:30, and the stirring speed is 600 rpm.

[0115] Test Example 1: Test on the treatment effect of actual pharmaceutical wastewater with different salt contents after electrodialysis treatment.

[0116] Test sample: the effluent from the concentration chamber after electrodialysis treatment in Example 1.

[0117] 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 chloride ions and acetate ions are detected based on ion chromatography.

[0118] The actual treatment effect of industrial wastewater with different salts after electrodialysis treatment is 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 the wastewater, and can effectively reduce the content of related ions and organic matter in the freshwater wastewater.

[0119] Experimental Example 2: Antibiotic adsorption test of polyacrylonitrile composite nanofiber membrane.

[0120] Test samples: polyacrylonitrile composite nanofiber membranes prepared in Examples 2-5 and Comparative Examples 1-3.

[0121] Test method: Cut the polyacrylonitrile composite nanofiber membrane into samples of the same size and mass and immerse them completely in a solution of C 0 tetracycline solution, after light protection, oscillate and adsorb at 25°C for 4 hours at a shaking speed of 130 rpm. After filtration, the supernatant was taken and the absorbance was measured by UV spectrophotometer to calculate the tetracycline concentration after the adsorption time. C t .

[0122] The adsorption removal rate of tetracycline by polyacrylonitrile composite nanofiber membrane is calculated as follows:

[0123] Where: R is the adsorption removal rate, C 0 is the initial tetracycline concentration, C t is the tetracycline concentration after adsorption time.

[0124] The antibiotic adsorption test results of the polyacrylonitrile composite nanofiber membrane prepared by the present invention are shown in Table 1: Table 1 Antibiotic adsorption test results of polyacrylonitrile composite nanofiber membrane

[0125] Compared with Example 2, Example 3 adjusted the ratio of pentaacetic acid α-D-mannose in the modified silica gel, so that tetracycline can enter the membrane and be adsorbed more easily; Example 4 introduced aniline methyl triethoxysilane to prepare modified silica gel, in which the amino and ethoxy silane groups can interact with the polyacrylonitrile molecular chain to form a more complex network structure, thereby enhancing the adsorption capacity of tetracycline; Example 5 increased 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 only uses calcium lactobionate to prepare the modified silica gel, lacks pentaacetate α-D-mannose, 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 pentaacetate α-D-mannose 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 then 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.

[0126] Experimental Example 3: Volatile organic compound separation test of polyacrylonitrile composite nanofiber membrane.

[0127] Test samples: polyacrylonitrile composite nanofiber membranes prepared in Examples 2-5 and Comparative Examples 1-3.

[0128] Test method: Cut the polyacrylonitrile composite nanofiber membrane into samples of the same size and mass, and filter 50 mL of a concentration of C 0 toluene solution, and the fluorescence intensity was measured by a fluorescence spectrophotometer to calculate the toluene concentration after filtration. C t .

[0129] The retention rate of toluene by polyacrylonitrile composite nanofiber membrane is calculated as follows:

[0130] Where: R is the interception rate, C 0 is the initial toluene concentration, C t is the toluene concentration after adsorption time.

[0131] The volatile organic compound separation test results of the polyacrylonitrile composite nanofiber membrane prepared by the present invention are shown in Table 2: Table 2 Volatile organic compound separation test results of polyacrylonitrile composite nanofiber membrane

[0132] 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, 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 pentaacetic acid α-D-mannose, so that the polyacrylonitrile composite nanofiber membrane has better mechanical strength and stability, and can continuously and stably play a filtering role, and the toluene retention rate is also improved compared with Example 2. 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.

[0133] 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.

[0134] 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 method for separating, recovering and recycling a variety of 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; introduce the concentrated water into the electrodialysis concentration system and RO reverse osmosis system, and separate the thiocyanate ions and chloride ions through concentration and crystallization. After concentration adjustment, they can be reused in the front-end process or purified for sale.

2. According to claim 1, a method for separating, recovering and recycling multiple valuable substances from pharmaceutical wastewater, 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 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. According to the method for separating, recovering and recycling multiple valuable substances from pharmaceutical wastewater as claimed in claim 2, 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, stirred to react to form a sol, and then aged, solvent exchanged, and vacuum-freeze-dried to obtain a modified silica gel; Polyacrylonitrile is dissolved in N,N-dimethylformamide to form a uniform solution, deionized water is 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, the 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 ultrasonicated 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. A 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 pentaacetic acid α-D-mannose 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. According to claim 3, a method for separating, recovering and recycling multiple valuable substances from pharmaceutical wastewater, 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 recycling multiple valuable substances from pharmaceutical wastewater according to claim 1, wherein the electrodialysis system comprises 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 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 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 comprises an electrode chamber water tank for storing an anode 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 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 solutes in 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 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.

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 0.1-0.9nm, 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 can be carried out by intermittent distillation, continuous distillation, extractive distillation and azeotropic distillation; the extractive distillation is operated at normal pressure, the reflux ratio is 1-8, the tower top temperature is 60-80°C, the tower bottom temperature is 110-130°C, and the molar ratio of the extractant to the raw material liquid is 1-10:10-100; the extractant includes acetophenone, N-methylacetamide, methyl pyrrolidone, tributyl phosphate, and isopropyl acetate.

10. A method for separating, recovering and recycling multiple valuable substances from pharmaceutical wastewater according to claim 1, wherein the cooling crystallization is controlled 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 achieve the optimal crystallization conditions.

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