Recycling treatment method of cephalosporin antibiotic production wastewater

Abstract

The invention relates to a recycling treatment method of cephalosporin antibiotic production wastewater. The method comprises a wastewater flocculation treatment step, a hollow fiber membrane ultrafiltration treatment step, a step of carrying out concentration treatment on ultrafiltration produced water by adopting a reverse osmosis membrane, a step of carrying out salt separation treatment on reverse osmosis concentrated water by adopting a nanofiltration membrane, and a step of carrying out concentration treatment on nanofiltration produced water by adopting a reverse osmosis membrane. According to the method, water and salt (monovalent salt and divalent salt) are effectively recycled from the cephalosporin antibiotic production wastewater, the recycled water can be used as water for circulating cooling water, and the water quality of the water meets related requirements of the water for circulating cooling water of enterprises, so that the emission of pollutants is reduced, and even zero emission of sewage is realized; and the method has remarkable social benefits and economic benefits.

Description

Technical Field

[0001] This invention belongs to the field of industrial wastewater treatment technology, and in particular relates to a method for the reuse and treatment of cephalosporin antibiotic production wastewater. More specifically, it relates to a method for recovering water and salt from cephalosporin antibiotic production wastewater. Background Technology

[0002] Industrial wastewater refers to wastewater, sewage, and waste liquid generated during industrial production processes. It contains industrial raw materials, intermediate products, and finished products that are lost with the water, as well as pollutants generated during the production process. If this wastewater is discharged directly without proper treatment, it will cause serious pollution to the environment and affect the ecological balance and human health.

[0003] The pharmaceutical industry is a major contributor to water pollution in my country. Untreated pollutants discharged into the water supply can severely endanger water resources, making it a persistent concern and a key target for environmental protection departments at all levels. If pharmaceutical wastewater is discharged into natural water bodies without proper treatment, it will cause numerous adverse effects. For example, excessive nutrients in water bodies can lead to eutrophication, a serious problem for lakes and slow-moving water bodies. Increased inorganic salts in water can raise osmotic pressure, negatively impacting freshwater organisms and plant growth. In saline-alkali areas, salt in surface and groundwater will have a greater impact on soil quality. Furthermore, it can cause acute and chronic poisoning, waterborne infectious diseases, and long-term consumption of water containing these substances or eating organisms with accumulated substances (such as fish) may induce cancer.

[0004] According to the "Pharmaceutical Industry Water Pollutant Discharge Standard," pharmaceutical industrial wastewater is classified into six categories: fermentation, chemical synthesis, extraction, traditional Chinese medicine, bioengineering, and mixed preparations. As a manufacturer of cephalosporin antibiotic raw materials and their preparations, the applicant has a wide variety of products, complex production processes, and a large production scale. Its wastewater discharge mainly involves four categories: fermentation, chemical synthesis, extraction, and preparations. The combined characteristics of this wastewater are: complex composition, numerous types and high concentrations of organic pollutants, high and fluctuating COD (Chemical Oxygen Demand) and BOD (Biochemical Oxygen Demand) values, deep color, high salt content, high toxicity, and the presence of many substances that are difficult to degrade biologically, as well as microbial growth inhibitors, resulting in poor biodegradability. The main reason for this is that the production process of raw materials often involves several or even dozens of reaction steps, using several or even dozens of raw materials, with raw material consumption ratios sometimes reaching as high as 200:1. A large portion of these raw materials are discharged from the production system into the external environment as "wastewater." These "wastewaters" are highly polluting, toxic, and contain substances that are difficult to biodegrade. If they are not properly treated, they will damage water bodies and the ecological environment, causing serious impacts on human survival and living environment. Therefore, it is very important to effectively treat these "wastewaters" and eliminate their impact.

[0005] Currently, the applicant directly discharges the pretreated wastewater into the municipal wastewater treatment plant for further advanced treatment, and pays the treatment fees. Generally, the pretreatment includes mechanical treatment, biological wastewater treatment, and dissolved air flotation (DAF) treatment. Mechanical treatment includes structures such as screens, grit chambers, and primary sedimentation tanks to remove large particles and suspended solids from the wastewater. The treatment principle is to achieve solid-liquid separation through physical methods, separating pollutants from the wastewater; this is a commonly used wastewater treatment method. Biological wastewater treatment primarily aims to remove non-settleable suspended solids and dissolved biodegradable organic matter. Its main process is the activated sludge process, with anaerobic and aerobic tanks being important components. DAF treatment involves a dissolved air system that generates a large number of microbubbles in the water, causing air to adhere to suspended particles in the form of highly dispersed microbubbles, creating a density less than water. Utilizing buoyancy, these particles float on the surface, achieving solid-liquid separation to remove fine particles with a specific gravity close to that of water. After the above pretreatment, the wastewater generally has a pH of 6-9 and a COD of [missing information]. CRThe wastewater has the following specifications: Chemical Oxygen Demand (COD, potassium dichromate method) 300–400 mg / L, BOD5 (5-day biochemical oxygen demand) 50–200 mg / L, TDS (Total Dissolved Solids) 3000–6000 mg / L, hardness 30–100 mg / L, TN (Total Nitrogen) 50–70 mg / L, turbidity 30–70 NTU, and conductivity 3500–15000 μS / cm. The wastewater is then discharged into a municipal wastewater treatment plant for further advanced treatment to meet municipal discharge standards before being released.

[0006] In recent years, with the development of the manufacturing industry, industrial wastewater has been increasing. The wastewater treatment capacity of municipal sewage treatment plants is nearing saturation. Municipalities have begun to raise the requirements for enterprises' wastewater discharge standards, even requiring enterprises to treat wastewater themselves to achieve zero discharge. As a result, the original wastewater pretreatment is no longer sufficient to meet the municipal discharge standards. Enterprises need to carry out further advanced treatment of wastewater to reduce wastewater discharge and even achieve zero discharge.

[0007] In existing technologies, industrial wastewater treatment methods cover physical, biological, and chemical methods. Physical methods include gravity separation, flotation, and membrane technology; biological methods include activated sludge and biofilm processes; and chemical methods include coagulation, oxidation-reduction, and microelectrolysis.

[0008] Chinese patent document CN115340253A discloses a zero-discharge treatment system and method for coking wastewater. The treatment system includes a pretreatment system, a biochemical process treatment system, an advanced treatment system, and a concentrate zero-discharge system connected in sequence. The method is aimed at the wastewater generated during the coking production process.

[0009] Chinese patent document CN115140879A discloses a treatment process for slag flushing wastewater, including wastewater homogenization, air flotation flocculation, ceramic ultrafiltration, salt separation nanofiltration, wet oxidation, MVR1 crystallization, reverse osmosis, and MVR2 crystallization. This treatment process is for slag flushing wastewater generated in the steel industry.

[0010] Chinese patent document CN111547896A discloses a process and treatment method for treating oilfield operation wastewater. The process steps include buffer adjustment, three-phase eddy flotation treatment, oxidation and debinding treatment, coagulation and sedimentation treatment, ultrafiltration treatment, nanofiltration treatment and reverse osmosis treatment. This treatment process is specifically designed for oilfield operation wastewater.

[0011] As stated above, the applicant, as a manufacturer of cephalosporin antibiotic raw materials and their preparations, experiences wastewater characterized by complex composition, numerous and high concentrations of organic pollutants, high and fluctuating COD (Chemical Oxygen Demand) and BOD (Biochemical Oxygen Demand) values, deep color, and high salt content. This differs from the aforementioned coking wastewater, slag flushing wastewater, and oilfield operation wastewater. Furthermore, given the new requirements imposed by the municipality and the increased wastewater discharge standards, the pretreated wastewater cannot meet the discharge requirements. The company needs to conduct further research on solutions for advanced wastewater treatment to achieve water and salt recovery, reduce wastewater discharge, and even achieve zero wastewater discharge. Summary of the Invention

[0012] Technical issues

[0013] Therefore, the present invention was made in view of the above problems. The purpose of the present invention is to provide a method for the reuse treatment of wastewater from the production of cephalosporin antibiotics. The method effectively recovers water and salts (monovalent and divalent salts) from the wastewater from the production of cephalosporin antibiotics. The recovered water can be used as circulating cooling water because the water quality meets the relevant requirements for circulating cooling water in enterprises, reducing the discharge of pollutants and even achieving zero wastewater discharge.

[0014] Technical solution

[0015] According to an embodiment of the present invention, the method for reusing wastewater from cephalosporin antibiotic production provided by the present invention includes the following steps:

[0016] (1) Wastewater flocculation treatment

[0017] Wastewater is added to the flocculation reaction tank, along with sodium hydroxide and coagulant, while stirring to form small flocs from the suspended solids in the wastewater. Then, another flocculant is added, and under stirring, the small flocs form large flocs. The wastewater that has undergone the flocculation reaction enters the sedimentation tank for sedimentation. The supernatant is then filtered to obtain the filtered clear liquid.

[0018] The amount of sodium hydroxide added is such that the pH of the wastewater system is adjusted to 10-12; the coagulant is polyaluminum chloride, and the amount of coagulant added is such that the concentration of coagulant in the wastewater is 100-250 mg / L; the flocculant is polyacrylamide, and the amount of flocculant added is such that the concentration of flocculant in the wastewater is 0.3-0.6 mg / L.

[0019] (2) Hollow fiber membrane ultrafiltration treatment

[0020] The filtered liquid obtained in step (1) above is subjected to ultrafiltration treatment through one or more hollow fiber membrane modules, wherein the hollow fiber membrane is an external pressure hollow fiber membrane fiber, the filtration direction is from the outside to the inside, the trapped pollutants remain on the outside of the hollow fiber membrane fiber, and the permeate is drawn out from the inside of the membrane fiber by the inlet water pressure, thereby obtaining ultrafiltration permeate.

[0021] (3) The ultrafiltration permeate is concentrated using a reverse osmosis membrane.

[0022] The pH of the ultrafiltration permeate obtained in step (2) above was adjusted to 6-8 using concentrated sulfuric acid, and then concentrated using a reverse osmosis membrane with a molecular weight cutoff of 50-150 Daltons to obtain reverse osmosis permeate and concentrate. The reverse osmosis permeate had a pH of 6-8 and a COD of 100-150 Daltons. CR ≤60mg / L, BOD5≤10mg / L, TDS≤500mg / L, hardness≤10mg / L, TN (total nitrogen)≤5mg / L, turbidity≤5NTU, conductivity<50μS / cm;

[0023] (4) Use nanofiltration membranes to desalinate reverse osmosis concentrate.

[0024] The reverse osmosis concentrate obtained in step (3) above is subjected to nanofiltration treatment using a nanofiltration membrane with a molecular weight cutoff of 150 to 300 Daltons to obtain nanofiltration permeate containing monovalent salt and nanofiltration concentrate containing divalent salt; the nanofiltration concentrate containing divalent salt is concentrated by evaporation to obtain crude sodium sulfate.

[0025] (5) Nanofiltration permeate is concentrated using a reverse osmosis membrane.

[0026] The nanofiltration permeate obtained in step (4) above is concentrated using a reverse osmosis membrane with a molecular weight cutoff of 50–150 Daltons to obtain secondary reverse osmosis permeate and secondary reverse osmosis concentrate. The secondary reverse osmosis permeate has a pH of 6–8 and a COD of 100–200%. CR The concentrations of sodium chloride and sodium nitrate are as follows: ≤60mg / L, BOD5≤10mg / L, TDS≤500mg / L, hardness≤10mg / L, TN (total nitrogen)≤5mg / L, turbidity≤5NTU, and conductivity less than 50μS / cm. The secondary reverse osmosis concentrate is then concentrated by evaporation to obtain a mixed salt of sodium chloride and sodium nitrate.

[0027] Beneficial effects

[0028] In this invention, by employing wastewater flocculation treatment, hollow fiber membrane ultrafiltration treatment, reverse osmosis membrane concentration treatment of ultrafiltration permeate, nanofiltration membrane desalination treatment of reverse osmosis concentrate, and nanofiltration permeate concentration treatment using reverse osmosis membrane, water and salt are recovered from cephalosporin antibiotic production wastewater. The recovered permeate has a pH of 6-8 and a COD of [missing information]. CRWith a concentration of ≤60mg / L, BOD5≤10mg / L, TDS≤500mg / L, hardness≤10mg / L, TN (total nitrogen)≤5mg / L, turbidity≤5NTU, and conductivity less than 50μS / cm, it fully meets or exceeds the requirements for factory circulating water and can be used as circulating cooling water. At the same time, it recovers monovalent salts (sodium nitrate and sodium chloride) and divalent salts (sodium sulfate) products, which can achieve the goal of zero wastewater discharge and has significant social and economic benefits. Attached Figure Description

[0029] Figure 1 This is a process flow diagram of the method for reusing wastewater from the production of cephalosporin antibiotics according to the present invention.

[0030] Figure 2 A schematic diagram of the hollow fiber membrane module structure used in this invention is shown. Detailed Implementation

[0031] The following detailed description of the method for treating and reusing wastewater from cephalosporin antibiotic production according to the present invention aims to facilitate understanding of the invention. However, various modifications can be made to the embodiments of the present invention, and the scope of the invention is not limited to the embodiments described below. The provision of embodiments of the present invention makes this disclosure clear and complete, in order to fully illustrate the invention to those skilled in the art.

[0032] Figure 1 This is a process flow diagram of the wastewater reuse treatment method for cephalosporin antibiotic production of the present invention. The method includes: (1) wastewater flocculation treatment; (2) hollow fiber membrane ultrafiltration treatment; (3) concentration treatment of ultrafiltration permeate using reverse osmosis membrane; (4) salt separation treatment of reverse osmosis concentrate using nanofiltration membrane; and (5) concentration treatment of nanofiltration permeate using reverse osmosis membrane.

[0033] According to an embodiment of the present invention, in the wastewater flocculation treatment in step (1), wastewater is added to the flocculation reaction tank, sodium hydroxide and coagulant are added to it, and stirring is carried out at the same time, so that the suspended matter in the wastewater forms small flocs; then the coagulant is added to it, so that the small flocs form large flocs under stirring; the wastewater after flocculation reaction enters the sedimentation tank for sedimentation, and the supernatant of the sediment is filtered to obtain the filtered clear liquid.

[0034] The wastewater used in step (1) of this invention, as described above, is pretreated wastewater with a pH generally between 6 and 9 and a COD of [missing information]. CRThe concentrations of phosphorus, nitrogen, and phosphorus are 300–400 mg / L, BOD5 is 50–200 mg / L, TDS is 3000–6000 mg / L, hardness is 30–100 mg / L, TN (total nitrogen) is 50–70 mg / L, turbidity is 30–70 NTU, and conductivity is 3500–15000 μS / cm.

[0035] Specifically, wastewater is added to the flocculation reaction tank, along with sodium hydroxide and a coagulant, while the mixture is stirred. The sodium hydroxide can be added as a sodium hydroxide solution, for example, a 15wt% to 32wt% (e.g., 30wt%) sodium hydroxide solution. The amount of sodium hydroxide added is such that the pH of the wastewater system is adjusted to 10 to 12, preferably 10.5 to 11.5. The coagulant is polyaluminum chloride, which can be added as a polyaluminum chloride solution, for example, a 5wt% to 10wt% polyaluminum chloride solution. The amount of coagulant added is such that the concentration of the coagulant in the wastewater is 100 to 250 mg / L. Sodium hydroxide and polyaluminum chloride (PAC) coagulant are added to the wastewater. With the help of a stirrer, the pH of the wastewater is adjusted to 10-12, preferably 10.5-11.5. At the same time, the suspended solids in the wastewater are rapidly mixed, and the particles are destabilized by neutralizing the negative charge on the particle surface, forming small flocs. This process usually takes 5-30 minutes, for example, 5-20 minutes or 15 minutes.

[0036] Then, a flocculant, namely polyacrylamide, is added. The polyacrylamide can be added in the form of a polyacrylamide solution, for example, a polyacrylamide solution of 0.1 wt% to 0.3 wt% (e.g., 0.1 wt%). The amount of flocculant added is such that the flocculant concentration in the wastewater is 0.3 to 0.6 mg / L. The flocculant promotes the formation of larger flocs from small flocs through adsorption, charge neutralization and mutual bridging. This process usually takes 15 to 30 minutes, for example, 15 minutes.

[0037] The wastewater that has undergone flocculation enters a sedimentation tank and settles for 30–60 minutes. The supernatant is then filtered through a sand filter or bag filter to obtain a clear filtrate. At this point, the coagulated flocs settle to the bottom of the sedimentation tank, forming sludge. This sludge can be returned to the flocculation reaction tank, or it can be concentrated and pressure filtered. The resulting sludge cake is then sent for external disposal, such as landfill.

[0038] As described above, in the wastewater flocculation treatment in step (1), most of the calcium ions and most of the suspended solids in the water can be removed.

[0039] According to an embodiment of the present invention, in the hollow fiber membrane ultrafiltration process in step (2), the filtered liquid obtained in step (1) is subjected to ultrafiltration treatment through one or more parallel hollow fiber membrane modules, wherein the hollow fiber membrane is an external pressure hollow fiber membrane fiber, the filtration direction is from the outside to the inside, the trapped pollutants remain on the outside of the hollow fiber membrane fiber, and the permeate is drawn out from the inside of the membrane fiber by the inlet water pressure, thereby obtaining ultrafiltration permeate.

[0040] The hollow fiber ultrafiltration membrane is used to remove tiny suspended solids that have not yet settled completely. The hollow fiber membrane is made of polyvinylidene fluoride (PVDF) and has internal reinforcing ribs to enhance the strength of the membrane fibers. The membrane pore size is approximately 0.03–0.05 micrometers, for example, 0.03–0.04 micrometers. Such membranes are commercially available, for example, from KOCH Corporation in the United States. Figure 2 A schematic diagram of the hollow fiber membrane module structure used in this invention is shown, as follows: Figure 2 As shown, the hollow fiber membrane module adopts a single-head encapsulation design. The hollow fiber membrane filaments are only fixed and encapsulated at the top end, while the bottom end is sealed and can swing freely. The encapsulation at the top allows the membrane filaments to swing freely during the scrubbing process and also allows the air to penetrate more completely into the membrane bundle. The open flow channel design of the membrane module allows the loosened solid matter to fall to the bottom of the membrane bundle, avoiding the formation of dead zones where pollutants can accumulate.

[0041] The filtered liquid obtained in step (1) is subjected to ultrafiltration through one or more, preferably two or more parallel hollow fiber membrane modules. During the ultrafiltration process, the operating pressure is generally controlled at 0.1 to 0.2 MPa. In large-scale circulation treatment, the ultrafiltration permeate can even reach 95% of the influent volume. The ultrafiltration concentrate can be returned to the wastewater flocculation treatment in step (1).

[0042] In addition, when there is contamination on the membrane surface, backwashing or chemical cleaning can be performed as needed.

[0043] According to an embodiment of the present invention, in step (3) of the ultrafiltration permeate being concentrated using a reverse osmosis membrane, concentrated sulfuric acid is used to adjust the pH of the ultrafiltration permeate obtained in step (2) to 6-8, and then a reverse osmosis membrane with a molecular weight cutoff of 50-150 Daltons is used to concentrate it to obtain reverse osmosis permeate and concentrated water.

[0044] Specifically, the pH of the ultrafiltration permeate obtained in step (2) is adjusted to 6-8, preferably 7-7.5, using concentrated sulfuric acid, such as 98 wt% concentrated sulfuric acid. Then, the pH-adjusted ultrafiltration permeate is desalinated and concentrated using a reverse osmosis membrane with a molecular weight cutoff of 50-150 Daltons, preferably 100-150 Daltons, at an inlet pressure of 2.0 MPa. The reverse osmosis membrane is a polyamide composite membrane, such as the SW30 series or BW30 series membranes from Dow Chemical Company.

[0045] Therefore, by using reverse osmosis membrane desalination to remove most of the organic matter and salts from the water, the recovered permeate fully meets or exceeds the requirements of the plant's circulating water. The reverse osmosis permeate has a pH of 6-8 and a COD of [missing information]. CR With concentrations ≤60 mg / L, BOD5 ≤10 mg / L, TDS ≤500 mg / L, hardness ≤10 mg / L, TN (total nitrogen) ≤5 mg / L, turbidity ≤5 NTU, and conductivity less than 50 μS / cm, it can be used as circulating cooling water. In this step, the recovery rate of the recycled water reaches approximately 85% or more, even reaching 90%.

[0046] The resulting concentrated water, which accounts for about 10% of the influent, contains a high concentration of inorganic salts, mainly including monovalent salts (such as sodium chloride and sodium nitrate) and divalent salts (such as sodium sulfate). The TDS concentration is about 10 times that of the raw water, for example, about 35,000 mg / L. This portion of the concentrated water will proceed to the next step for further treatment.

[0047] According to an embodiment of the present invention, in step (4) of using a nanofiltration membrane to desalinate the reverse osmosis concentrate, a nanofiltration membrane with a molecular weight cutoff of 150 to 300 Daltons is used to perform nanofiltration treatment on the reverse osmosis concentrate obtained in step (3) above, to obtain nanofiltration permeate containing monovalent salts and nanofiltration concentrate containing divalent salts; the nanofiltration concentrate containing divalent salts is then concentrated by evaporation to obtain crude sodium sulfate.

[0048] The nanofiltration membrane is a polyamide composite membrane, such as the NF90 series membrane from Dow Chemical Company. The reverse osmosis concentrate obtained in step (3) above is treated with a nanofiltration membrane with a molecular weight cutoff of 150 to 300 Daltons. Monovalent salts pass through the nanofiltration membrane and enter the nanofiltration permeate, while divalent salts are retained in the nanofiltration concentrate.

[0049] In nanofiltration, with an influent pressure of 1.5 MPa, the salts in the reverse osmosis concentrate are separated into two parts. For example:

[0050] Nanofiltration permeate (accounting for approximately 75% of the nanofiltration feed water): mainly contains monovalent salts (sodium chloride and sodium nitrate), with a monovalent salt concentration of approximately 15,000 mg / L;

[0051] Nanofiltration concentrate (approximately 25% of the nanofiltration feed water): mainly contains divalent salts (sodium sulfate), with a concentration of approximately 90,000 mg / L.

[0052] The nanofiltration concentrate containing divalent salts is evaporated and concentrated to obtain crude sodium sulfate with a purity of approximately 92%, which can be further refined.

[0053] According to an embodiment of the present invention, in step (5) of concentrating the nanofiltration permeate using a reverse osmosis membrane, a reverse osmosis membrane with a molecular weight cutoff of 50-150 Daltons is used to concentrate the nanofiltration permeate obtained in step (4) to obtain secondary reverse osmosis permeate and secondary reverse osmosis concentrate. The secondary reverse osmosis permeate has a pH of 6-8 and a COD of [missing information]. CR The concentrations of sodium chloride and sodium nitrate are as follows: ≤60mg / L, BOD5≤10mg / L, TDS≤500mg / L, hardness≤10mg / L, TN (total nitrogen)≤5mg / L, turbidity≤5NTU, and conductivity less than 50μS / cm. The secondary reverse osmosis concentrate is then concentrated by evaporation to obtain a mixed salt of sodium chloride and sodium nitrate.

[0054] Specifically, the reverse osmosis membrane used in step (5) is the same as that used in step (3), that is, a reverse osmosis membrane with a molecular weight cutoff of 50-150 Daltons, preferably 100-150 Daltons, is used to desalinate and concentrate the nanofiltration permeate obtained in step (4), with an inlet pressure of 2.0 MPa. The reverse osmosis membrane is a polyamide composite membrane, such as the SW30 series or BW30 series membranes from Dow Chemical Company.

[0055] Therefore, through reverse osmosis membrane desalination, the recovered secondary reverse osmosis permeate fully meets or exceeds the requirements of the plant's circulating water, with a pH value of 6-8 and a COD of [missing information]. CR With a concentration ≤60mg / L, BOD5 ≤10mg / L, TDS ≤500mg / L, hardness ≤10mg / L, TN (total nitrogen) ≤5mg / L, turbidity ≤5NTU, and conductivity less than 50μS / cm, it can be used as circulating cooling water. In this step, the recovered product water rate is approximately 80%.

[0056] The resulting secondary reverse osmosis concentrate accounts for about 20% of the feed water and contains high concentrations of monovalent salts sodium chloride and sodium nitrate, with a TDS concentration of about 60,000 mg / L. This concentrate is evaporated and concentrated to obtain a mixed salt of sodium chloride and sodium nitrate, which can be further purified.

[0057] As described above, in this invention, by employing wastewater flocculation treatment, hollow fiber membrane ultrafiltration treatment, reverse osmosis membrane concentration treatment of ultrafiltration permeate, nanofiltration membrane salt separation treatment of reverse osmosis concentrate, and nanofiltration permeate concentration treatment using reverse osmosis membrane, water and salt are recovered from cephalosporin antibiotic production wastewater. The recovered permeate fully meets or exceeds the requirements of the factory's circulating water and can be used as circulating cooling water. At the same time, monovalent salts (sodium nitrate and sodium chloride) and divalent salts (sodium sulfate) are recovered, achieving the goal of zero wastewater discharge and demonstrating significant social and economic benefits.

[0058] The following examples illustrate the method for recycling wastewater from cephalosporin antibiotic production according to the present invention in more detail, but the scope of protection of the present invention is not limited to these examples.

[0059] Example 1

[0060] (1) Wastewater flocculation treatment

[0061] Wastewater (pH: 7.8, COD) was added to the flocculation reaction tank. CR 380 mg / L, BOD5: 100 mg / L, TDS: 3700 mg / L, Hardness: 83 mg / L, Total Nitrogen: 57 mg / L, Turbidity: 45 NTU, Conductivity: 8500 μS / cm²m 3 Add 3L of 30wt% sodium hydroxide solution and 10wt% polyaluminum chloride solution to the wastewater while stirring to adjust the pH of the wastewater system to 11.5. The suspended solids in the wastewater form small flocs, which takes about 10 minutes. Then add 1L of 0.1wt% polyacrylamide solution, which, under stirring, causes the small flocs to form large flocs, which takes about 15 minutes. The wastewater that has undergone flocculation reaction enters the sedimentation tank and settles for 1 hour. The supernatant of the sediment is filtered through a bag filter to obtain the filtered clear liquid.

[0062] (2) Hollow fiber membrane ultrafiltration treatment

[0063] The filtered liquid obtained in step (1) above was subjected to ultrafiltration through two parallel hollow fiber membrane modules (MBR membranes from KOCH, USA). During the ultrafiltration process, the operating pressure was generally controlled at 0.1–0.2 MPa, yielding approximately 1.7 m³ of ultrafiltration permeate. 3 The concentrate is approximately 0.2m. 3 .

[0064] The ultrafiltration permeate has a pH of 11.3 and a TDS of 3300 mg / L.

[0065] The ultrafiltration concentrate can be returned to the wastewater flocculation treatment in step (1).

[0066] (3) The ultrafiltration permeate is concentrated using a reverse osmosis membrane.

[0067] The pH of the ultrafiltration permeate obtained in step (2) was adjusted to 7.2 using 98 wt% concentrated sulfuric acid. Then, the pH-adjusted ultrafiltration permeate was desalinated and concentrated using a reverse osmosis membrane (Dow Chemical Company SW30-2540) with a molecular weight cutoff of 100 Daltons. The influent pressure was 2.0 MPa, yielding approximately 1.5 m³ of reverse osmosis permeate. 3 Approximately 0.2m of concentrated water. 3 .

[0068] Product water pH: 7.1, COD CR 37 mg / L, BOD5: 8 mg / L, TDS: 50 mg / L, Hardness: 8 mg / L, Conductivity: 41 μS / cm, TN: 4 mg / L, Turbidity: 3 NTU, can be used as circulating cooling water.

[0069] Concentrate pH: 7.2, TDS: 34400 mg / L.

[0070] (4) Use nanofiltration membranes to desalinate reverse osmosis concentrate.

[0071] The reverse osmosis concentrate obtained in step (3) above was subjected to nanofiltration treatment using a nanofiltration membrane with a molecular weight cutoff of 300 Daltons (Dow Chemical Company, NF90-2540 membrane), yielding approximately 0.15 m³ of nanofiltration permeate containing monovalent salts. 3 And approximately 0.05m of nanofiltration concentrate containing divalent salts. 3 ;

[0072] Nanofiltration permeate, TDS: 14400 mg / L, pH: 7.2;

[0073] Nanofiltration concentrate, TDS: 84400 mg / L, pH: 7.2

[0074] The nanofiltration concentrate containing divalent salt was concentrated by evaporation to obtain 4250g of crude sodium sulfate with a purity of 92%.

[0075] (5) Nanofiltration permeate is concentrated using a reverse osmosis membrane.

[0076] A reverse osmosis membrane (Dow Chemical Company SW30-2540 membrane) with a molecular weight cutoff of 100 Daltons was used to process 0.15m of nanofiltration permeate. 3 Desalination and concentration treatment was performed at an influent pressure of 2.0 MPa, yielding approximately 0.12 m³ of secondary reverse osmosis permeate. 3 And approximately 0.03m of concentrated water. 3 .

[0077] Secondary reverse osmosis permeate: COD CR46 mg / L, BOD5: 9 mg / L, pH: 7.2, hardness: 8 mg / L, TDS: 145 mg / L, conductivity: 47 μS / cm, TN: 5 mg / L, turbidity: 4 NTU, can be used as circulating cooling water;

[0078] Secondary reverse osmosis concentrate, TDS: 62100 mg / L, pH: 7.2

[0079] The secondary reverse osmosis concentrate was evaporated and concentrated to obtain 1870g of a mixed salt of sodium chloride and sodium nitrate. The purity of sodium chloride was 92% and the purity of sodium nitrate was 93%. The mixing ratio of sodium chloride and sodium nitrate was 75:25.

[0080] Example 2

[0081] (1) Wastewater flocculation treatment

[0082] Wastewater (pH: 7.3, COD) was added to the flocculation reaction tank. CR 360 mg / L, BOD5: 90 mg / L, TDS: 3750 mg / L, Hardness: 81 mg / L, Total Nitrogen: 57 mg / L, Turbidity: 44 NTU, Conductivity: 8700 μS / cm 3 Add approximately 8 L of 30 wt% sodium hydroxide solution and 10 wt% polyaluminum chloride solution to the wastewater while stirring to adjust the pH of the wastewater system to 11.2. The suspended solids in the wastewater will form small flocs, which will take about 15 minutes. Then, add approximately 2.5 L of 0.1 wt% polyacrylamide solution to the wastewater. Under stirring, the small flocs will form large flocs, which will take about 30 minutes. The wastewater that has undergone the flocculation reaction will enter the sedimentation tank and settle for 1 hour. The supernatant of the sediment will be filtered through a bag filter to obtain the filtered clear liquid.

[0083] (2) Hollow fiber membrane ultrafiltration treatment

[0084] The filtered liquid obtained in step (1) above was subjected to ultrafiltration through two parallel hollow fiber membrane modules (MBR membranes from KOCH, USA). During the ultrafiltration process, the operating pressure was generally controlled at 0.1–0.2 MPa, yielding approximately 4.4 m³ of ultrafiltration permeate. 3 The concentrate is approximately 0.4 m³. 3 .

[0085] The ultrafiltration permeate has a pH of 11.5 and a TDS of 3350 mg / L.

[0086] The ultrafiltration concentrate can be returned to the wastewater flocculation treatment in step (1).

[0087] (3) The ultrafiltration permeate is concentrated using a reverse osmosis membrane.

[0088] The pH of the ultrafiltration permeate obtained in step (2) was adjusted to 7.2 using 98 wt% concentrated sulfuric acid. Then, the pH-adjusted ultrafiltration permeate was desalinated and concentrated using a reverse osmosis membrane (Dow Chemical Company SW30-2540) with a molecular weight cutoff of 100 Daltons. The influent pressure was 2.0 MPa, yielding approximately 3.9 m³ of reverse osmosis permeate. 3 Approximately 0.5m of concentrated water. 3 .

[0089] The product water pH is 7.2, COD CR 38 mg / L, BOD5: 7 mg / L, TDS: 46 mg / L, Hardness: 8 mg / L, Conductivity: 40 μS / cm, TN: 4 mg / L, Turbidity: 3 NTU, can be used as circulating cooling water.

[0090] Concentrate pH: 7.2, TDS: 30480 mg / L.

[0091] (4) Use nanofiltration membranes to desalinate reverse osmosis concentrate.

[0092] The reverse osmosis concentrate obtained in step (3) above was subjected to nanofiltration treatment using a nanofiltration membrane (Dow Chemical Company, NF90-2540 membrane) with a molecular weight cutoff of 300 Daltons, yielding approximately 0.37 m³ of nanofiltration permeate containing monovalent salts. 3 And approximately 0.13m of nanofiltration concentrate containing divalent salts. 3 ;

[0093] Nanofiltration permeate, TDS: 12300 mg / L, pH: 7.2;

[0094] Nanofiltration concentrate, TDS: 85000 mg / L, pH: 7.2

[0095] The nanofiltration concentrate containing divalent salt was evaporated and concentrated to obtain 11,700 g of crude sodium sulfate with a purity of 93%.

[0096] (5) Nanofiltration permeate is concentrated using a reverse osmosis membrane.

[0097] A reverse osmosis membrane (Dow Chemical Company SW30-2540 membrane) with a molecular weight cutoff of 100 Daltons was used to process 0.37m of nanofiltration permeate. 3 Desalination and concentration treatment was performed at an influent pressure of 2.0 MPa, yielding approximately 0.27 m³ of secondary reverse osmosis permeate. 3 Approximately 0.10m of concentrated water. 3 .

[0098] Secondary reverse osmosis permeate: COD CR47 mg / L, BOD5: 8 mg / L, pH: 7.2, hardness: 8 mg / L, TDS: 130 mg / L, conductivity: 46 μS / cm, TN: 5 mg / L, turbidity: 4 NTU, can be used as circulating cooling water;

[0099] Secondary reverse osmosis concentrate, TDS: 56900 mg / L, pH: 7.2

[0100] The secondary reverse osmosis concentrate was evaporated and concentrated to obtain 5700g of a mixed salt of sodium chloride and sodium nitrate. The purity of sodium chloride was 93% and the purity of sodium nitrate was 93%. The mixing ratio of sodium chloride and sodium nitrate was 77:23.

Claims

1. A method for reusing and treating cephalosporin antibiotic production wastewater, comprising the following steps: (1) flocculation treatment of wastewater In the flocculation reaction tank, the wastewater is added, sodium hydroxide and coagulant are added thereto while stirring, so that the suspended solids in the wastewater form small flocs; then a flocculant is added, so that under stirring, the small flocs form large flocs; the wastewater after flocculation reaction enters a sedimentation tank for sedimentation, the supernatant of the sedimentation is filtered to obtain filtered supernatant; wherein The amount of sodium hydroxide added is such that the pH of the wastewater system is adjusted to 10-12; the coagulant is polyaluminum chloride, and the amount of coagulant added is such that the concentration of coagulant in the wastewater is 100-250 mg / L; the flocculant is polyacrylamide, and the amount of flocculant added is such that the concentration of flocculant in the wastewater is 0.3-0.6 mg / L; (2) ultrafiltration treatment by hollow fiber membrane The filtered supernatant obtained in step (1) is subjected to ultrafiltration treatment by one or more hollow fiber membrane assemblies, wherein the hollow fiber membrane is an outer pressure type hollow fiber membrane, the filtration direction is from outside to inside, the trapped pollutants stay on the outside of the hollow fiber membrane, and the produced water is drawn from the inside of the membrane by water pressure, thereby obtaining ultrafiltration produced water; (3) concentration treatment of the ultrafiltration produced water by reverse osmosis membrane The pH of the ultrafiltration water obtained in step (2) is adjusted to 6-8 using concentrated sulfuric acid, and then the ultrafiltration water is concentrated using a reverse osmosis membrane with a molecular weight cut-off of 50-150 daltons to obtain reverse osmosis water and concentrated water, wherein the pH of the reverse osmosis water is 6-8, the COD CR ≤60 mg / L, the BOD5≤10 mg / L, the TDS≤500 mg / L, the hardness≤10 mg / L, the TN (total nitrogen)≤5 mg / L, the turbidity≤5 NTU, and the conductivity is less than 50 μS / cm. (4) desalination treatment of the reverse osmosis concentrated water by nanofiltration membrane The reverse osmosis concentrated water obtained in step (3) is subjected to nanofiltration treatment by a nanofiltration membrane with a molecular weight cut-off of 150-300 daltons, to obtain nanofiltration produced water containing monovalent salt and nanofiltration concentrated water containing divalent salt; the nanofiltration concentrated water containing divalent salt is evaporated and concentrated to obtain crude sodium sulfate salt; (5) concentration treatment of the nanofiltration produced water by reverse osmosis membrane The nanofiltration product water obtained in the above step (4) is concentrated by using a reverse osmosis membrane with a molecular weight cut-off of 50-150 Dalton to obtain secondary reverse osmosis product water and secondary reverse osmosis concentrated water, wherein the pH value of the secondary reverse osmosis product water is 6-8, COD CR ≤60 mg / L, BOD5≤10 mg / L, TDS≤500 mg / L, hardness≤10 mg / L, TN (total nitrogen) ≤5 mg / L, turbidity≤5 NTU, and conductivity less than 50 μS / cm; and the secondary reverse osmosis concentrated water is concentrated by evaporation to obtain a mixed salt of sodium chloride and sodium nitrate.

2. The method for reusing the cephalosporin antibiotic production wastewater according to claim 1, characterized by, The wastewater pH is 6-9, COD CR 300-400 mg / L, BOD5 is 50-200 mg / L, TDS is 3000-6000 mg / L, hardness is 30-100 mg / L, TN is 50-70 mg / L, turbidity is 30-70 NTU, conductivity is 3500-15000 μS / cm.

3. The method for reusing the cephalosporin antibiotic production wastewater according to claim 1 or 2, characterized by, in In the wastewater flocculation treatment of step (1), the sodium hydroxide is added in the form of a 15wt%-32wt% sodium hydroxide solution, the polyaluminum chloride is added in the form of a 5wt%-10wt% polyaluminum chloride solution, and the polyacrylamide is added in the form of a 0.1wt%-0.3wt% polyacrylamide solution.

4. The method for reusing the cephalosporin antibiotic production wastewater according to claim 1 or 2, characterized by, in In the wastewater flocculation treatment of step (1), the wastewater after flocculation reaction enters the sedimentation tank for sedimentation for 30-60 minutes, the supernatant of the sedimentation is filtered by a sand filter or a filter bag type filter to obtain filtered supernatant; the coagulation flocs are deposited to the bottom of the sedimentation tank to form sludge, which is returned to the flocculation reaction tank or is subjected to concentration and pressure filtration treatment to generate a cake which is sent out for treatment.

5. The method for reusing the cephalosporin antibiotic production wastewater according to claim 1 or 2, characterized by, in In the hollow fiber membrane ultrafiltration treatment of step (2), the hollow fiber membrane is made of polyvinylidene fluoride (PVDF) and has reinforcing ribs inside to enhance the strength of the membrane, and the membrane pore size is about 0.03-0.05 microns.

6. The method for reusing the cephalosporin antibiotic production wastewater according to claim 1 or 2, characterized by, in In the hollow fiber membrane ultrafiltration treatment of step (2), the hollow fiber membrane assembly adopts a single-head packaging design, and the hollow fiber membrane is only fixedly packaged at the top end and is sealed and not fixedly packaged at the bottom end.

7. The method for reusing the cephalosporin antibiotic production wastewater according to claim 1 or 2, characterized by, in In the step (3) of concentrating the ultrafiltration water by using a reverse osmosis membrane, the pH of the ultrafiltration water obtained in the step (2) is adjusted to 7-7.5 by using concentrated sulfuric acid, and then the pH-adjusted ultrafiltration water is desalted and concentrated by using a reverse osmosis membrane with a molecular weight cut-off of 100-150 daltons, and the water inlet pressure is 2.0 MPa, wherein the reverse osmosis membrane is a polyamide composite membrane.

8. The method for reusing the cephalosporin antibiotic production wastewater according to claim 1 or 2, characterized by, In the step (4) of separating the reverse osmosis concentrated water by using a nanofiltration membrane, the nanofiltration membrane is a polyamide composite membrane.

9. The method for reusing the cephalosporin antibiotic production wastewater according to claim 1 or 2, characterized by, in In the step (4) of separating the reverse osmosis concentrated water by using a nanofiltration membrane, the water inlet pressure in the nanofiltration process is 1.5 MPa.

10. The method for reusing the cephalosporin antibiotic production wastewater according to claim 1 or 2, characterized by, in In the step (5) of concentrating the nanofiltration water by using a reverse osmosis membrane, the nanofiltration water obtained in the step (4) is desalted and concentrated by using a reverse osmosis membrane with a molecular weight cut-off of 100-150 daltons, and the water inlet pressure is 2.0 MPa, wherein the reverse osmosis membrane is a polyamide composite membrane.

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