A method for treating complex industrial wastewater based on a new separation membrane technology

Abstract

The application provides a treatment method for complex industrial sewage based on a novel separation membrane technology, and relates to the technical field of sewage treatment. The method comprises the following steps: step 1: pumping the sewage into an oil-water separation column loaded with a single-layer hydrophilic membrane for preliminary filtration; step 2: passing the water into a quartz column loaded with a modified g-C3N4 or polyacrylonitrile membrane photocatalyst, and combining 330W xenon lamp for 1-2 hours of cyclic light irradiation purification; and step 3: passing into an adsorption column loaded with 3-5 pieces of chitosan-based fiber membrane, and cyclically filtering for 1.5-3 hours. Through the combined process of oil-water separation, photocatalytic pollution reduction and adsorption purification, the hydrophilicity, photocatalysis and chemical chelation of the separation membrane are utilized to realize efficient treatment and resource utilization of complex industrial sewage, and the method has environmental protection and economic benefits, has the potential of resource recycling and pollution resistance, significantly reduces the replacement frequency of the membrane material and the operation cost of the sewage treatment, and has a wide market application prospect.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a method for treating complex industrial wastewater based on a novel separation membrane technology. Background Technology

[0002] With rapid economic development and accelerated industrialization, wastewater discharge from daily industrial production activities is increasing year by year. Traditional wastewater treatment processes are rigid, with problems such as long comprehensive treatment processes, large facility footprints, limited removal capacity for complex and highly hazardous pollutants, susceptibility to secondary pollution, difficulty in resource recovery, and high cost of reagents and energy. In contrast, membrane separation technology has outstanding advantages such as high treatment efficiency, small footprint, no secondary pollution, and the ability to simultaneously achieve pollutant interception and water resource and valuable component recovery.

[0003] However, existing membrane-based wastewater treatment technologies still suffer from several major drawbacks, including severe membrane fouling, difficulties in treating complex wastewater in actual production, high investment and operating costs, stringent requirements for influent pretreatment, insufficient comprehensive wastewater resource recovery capacity, and high energy consumption. Furthermore, traditional membrane materials are often difficult to degrade, have poor hydrophilicity, poor selectivity, limited functionality, and lack active functional groups. These factors significantly restrict the application prospects of membrane-based technologies for complex industrial wastewater in actual industrial production.

[0004] Therefore, those skilled in the art have provided a method for treating complex industrial wastewater based on novel separation membrane technology to solve the problems mentioned in the background art. Summary of the Invention

[0005] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a method for treating complex industrial wastewater based on novel separation membrane technology. By combining oil-water separation, photocatalytic pollution reduction, and adsorption purification, and utilizing the hydrophilicity, photocatalysis, and chemical chelation of the separation membrane, this method achieves efficient treatment and resource recovery of complex industrial wastewater, combining environmental protection and economic benefits.

[0006] (II) Technical Solution To achieve the above objectives, the present invention provides the following technical solution: A method for treating complex industrial wastewater based on a novel separation membrane technology includes the following steps: Step 1: Slowly pump the wastewater into an oil-water separation column loaded with a single layer of hydrophilic membrane for simple single-pass filtration. After filtration, the water is preliminarily purified. Step 2: Continue to pass the pre-purified water into a photocatalytic quartz column loaded with a high-efficiency photocatalytic membrane, and continue to perform circulation filtration and illumination to complete the further purification of the water. The photocatalytic membrane is a single sheet of modified g-C3N4 polyacrylonitrile membrane with no risk of metal leaching. The circulation filtration time and the illumination time of the 330W xenon lamp are both 1-2 hours. Step 3: Pass the further treated wastewater into an adsorption column loaded with chitosan-based fiber membrane sheets for circulating filtration; wherein, the standard chitosan-based fiber membrane sheet is composed of 3 standard chitosan-based fiber membrane sheets fixed by die casting, and 3-5 standard chitosan-based fiber membrane sheets need to be loaded in a single adsorption column; the circulation filtration time is 1.5-3 hours.

[0007] Furthermore, the oil-water separation column is prepared using the following method, including the following steps: S1: Dissolve 5 wt% cellulose acetate in a solution with a volume ratio of 2:1 acetic acid / dichloromethane to prepare a spinning solution; take 8 mL of the spinning solution and spin it on baking paper using electrospinning technology at a voltage of 18 kV and -2.5 kV and a speed of 0.35 mL / min. S2: Based on the actual size of the membrane column, take 3 standard-sized membrane sheets and place them in plastic petri dishes. Then, slowly pour in an appropriate amount of deacetylation solution and perform deacetylation treatment in a ventilated place for 12 hours. After treatment, dry them in a fume hood to obtain the hydrophilic membrane. The deacetylation solution is a 0.1-0.5 mol / L sodium hydroxide solution. S3: Stack the three prepared hydrophilic membranes together in an alternating pattern, soak them in water, clamp them with a hollow rubber sheet, and then fix them in a hollow container to obtain the desired oil-water separation column.

[0008] Furthermore, the processing procedure of the oil-water separation column includes the following steps: S1: The wastewater sample is pumped into the oil-water separation column through an external water pump. After the wastewater is naturally filtered through the membrane by gravity, the mineral oil and emulsified oil in the water can be quickly separated from the water. S2: Thanks to the hydrophilicity of the membrane, mineral oil and emulsion cannot be filtered through the membrane and are well retained, achieving preliminary purification of wastewater.

[0009] Furthermore, the photocatalytic quartz column is prepared using the following method, including the following steps: S1: Dissolve 5 wt% polyacrylonitrile powder in acetone or dimethyl sulfoxide solution at a volume ratio of 1:1, stir evenly, add 3 wt% modified g-C3N4 powder, and then sonicate for 15 min to disperse evenly and remove air bubbles. S2: Then take 5 mL of spinning solution and use electrospinning technology to spin single needle blends on baking paper at a speed of 0.15 mL / min under voltages of 22 kV and -2.5 kV. S3: Then cut the membrane into a standard size of 3x3cm, sprinkle it directly into the quartz column at a concentration of 1g / L, and then attach a stirrer to the top to obtain the desired photocatalytic quartz column.

[0010] Furthermore, the preparation method of the modified g-C3N4 powder used in the photocatalytic quartz column includes the following steps: S1: Mix commercially available industrial-grade g-C3N4 powder with NaCl, KCl and LiCl in a uniform mass ratio of 5:3:1:1; S2: Subsequently, the mixed powder is placed in a tube furnace and heated to 550°C at a rate of 1.5°C / min under argon conditions. It is then held at this temperature for 5 hours and allowed to cool naturally.

[0011] Furthermore, the processing procedure for the photocatalytic quartz column includes the following steps: S1: The pre-treated wastewater, which is free of obvious oil stains, is pumped into the photocatalytic quartz column from the lower interface. After the separation membrane-based catalyst is fully floated, the stirrer is turned on and the 330W xenon lamps on both sides are turned on for irradiation. S2: The catalytically treated wastewater is extracted from the top and circulated for 1.5-3 hours to complete the catalytic decontamination.

[0012] Furthermore, the adsorption column is prepared using the following method, including the following steps: S1: Dissolve 5 wt% chitosan / polyvinyl alcohol mixed powder in 90 vol% acetic acid solution, wherein the mass ratio of chitosan to polyvinyl alcohol is 1:9; S2: After the chitosan / polyvinyl alcohol mixed powder is evenly mixed, take 10 mL of spinning solution and use electrospinning technology to spin single needles on baking paper at a voltage of 23 kV and a speed of 0.25 mL / min. S3: Take three standard-sized chitosan-based fiber membrane sheets, stack them in an alternating manner, soak them in water, clamp them with hollow rubber sheets, and then fix them in a hollow container to obtain an adsorption column; S4: To ensure removal efficiency and purification depth, a single adsorption column needs to be loaded with 3-5 standard chitosan-based fiber membrane sheets.

[0013] Furthermore, the processing procedure for the adsorption column includes the following steps: S1: The purified wastewater with low oil and COD content, which has undergone deep treatment by oil-water separation and photocatalysis, is slowly pumped into the column cavity from the interface above the membrane column, so that the wastewater can fully contact and be naturally filtered by 3-5 layers of standard chitosan-based fiber membrane sheets. S2: Extract the adsorption-treated wastewater from the bottom and circulate it for 1.5-3 hours to complete the adsorption purification.

[0014] Furthermore, the processing flow of the adsorption column includes the following elution steps for heavy metal pollutants: S1: Mix the prepared 0.1mol / L thiourea and 0.2mol / L HCl in a volume ratio of 1:1. After stirring evenly, immerse the chitosan-based fiber membrane containing heavy metals such as Cu and Pb into it and soak for 15-30 minutes to complete the washing of 85-93% of the adsorbed heavy metals. S2: Then, rinse the de-washed chitosan-based fiber membranes 2-3 times with water and alcohol respectively, and let them air dry in a fume hood to achieve membrane recycling.

[0015] (III) Beneficial Effects This invention provides a method for treating complex industrial wastewater based on a novel separation membrane technology. It offers the following advantages: 1. This invention adopts a three-stage membrane column series relay treatment system. The oil-water separation column, photocatalytic quartz column and adsorption column are independent but complementary and work together to remove pollutants. They are used to remove mineral oil and emulsified oil, recalcitrant organic pollutant COD and heavy metal pollutants such as Cu and Pb in wastewater in a graded manner. It covers a wide range of pollutant types and has a high purification depth, making it suitable for industrial wastewater treatment scenarios with complex composition.

[0016] 2. The hydrophilic membrane contained in the oil-water separation column of the present invention is based on cellulose acetate membrane and modified by mild deacetylation, which generates a large number of hydrophilic groups -OH, forming a durable, environmentally friendly, low-cost and biodegradable hydrophilic membrane. It can be filtered by gravity without additional pressure, is easy to operate and has low energy consumption, and can quickly complete the separation of mineral oil and emulsification.

[0017] 3. The photocatalytic quartz column of this invention uses a polyacrylonitrile membrane supported on modified g-C3N4 as a catalyst. Combined with circulating filtration and xenon lamp irradiation to simulate sunlight, it achieves highly efficient degradation of low-to-medium concentration organic matter within -2 hours without the risk of metal leaching. Furthermore, using corrosion-resistant, low-cost, and highly resistant polyacrylonitrile as a raw material greatly extends the catalyst's lifespan, making the photocatalytic membrane more promising for practical applications. 4. The adsorption column of the present invention uses stacked green chitosan / polyvinyl alcohol composite electrospun fiber membrane as the core functional block. Each column is loaded with 3-5 standard membrane sheets stacked alternately, which increases the adsorption contact area and adsorption capacity. After 1.5-3 hours of circulating filtration, it can achieve deep adsorption and removal of high concentrations of heavy metals and residual organic matter.

[0018] 5. This invention emphasizes the concept of green development. In the oil-water separation column, high-value mineral oil can be recovered through interception. The core functional layer, namely the hydrophilic membrane, can be reused after simple rinsing with water. In the photocatalytic quartz column, corrosion-resistant polyacrylonitrile is used as the carrier of the active photocatalyst. The high-performance material and the self-cleaning effect of the photocatalytic membrane greatly extend the service life of the membrane. Finally, in the adsorption column, the adsorption-saturated chitosan-based fiber membrane can be leached and washed with a mixture of thiourea and hydrochloric acid, achieving a heavy metal removal rate of 85-93%. After a simple sedimentation treatment, heavy metal resources can be recovered, laying a good foundation for recovery. The membrane can then be recycled after simple rinsing with water and alcohol and drying. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0021] A method for treating complex industrial wastewater based on a novel separation membrane technology includes the following steps: Step 1: Slowly pump the wastewater into an oil-water separation column loaded with a single layer of hydrophilic membrane for simple single-pass filtration. After filtration, the water is preliminarily purified. Step 2: Continue to pass the pre-purified water into a photocatalytic quartz column loaded with a high-efficiency photocatalytic membrane, and continue to perform circulation filtration and illumination to complete the further purification of the water. The photocatalytic membrane is a single sheet of modified g-C3N4 polyacrylonitrile membrane with no risk of metal leaching. The circulation filtration time and the illumination time of the 330W xenon lamp are both 1-2 hours. Step 3: Pass the further treated wastewater into an adsorption column loaded with chitosan-based fiber membrane sheets for circulating filtration; wherein, the standard chitosan-based fiber membrane sheet is composed of 3 standard chitosan-based fiber membrane sheets fixed by die casting, and 3-5 standard chitosan-based fiber membrane sheets need to be loaded in a single adsorption column; the circulation filtration time is 1.5-3 hours.

[0022] Specifically, the oil-water separation column is prepared using the following method, including the following steps: S1: Dissolve 5 wt% cellulose acetate in a solution with a volume ratio of 2:1 acetic acid / dichloromethane to prepare a spinning solution; take 8 mL of the spinning solution and spin it on baking paper using electrospinning technology at a voltage of 18 kV and -2.5 kV and a speed of 0.35 mL / min. S2: Based on the actual size of the membrane column, take 3 standard-sized membrane sheets and place them in plastic petri dishes. Then, slowly pour in an appropriate amount of deacetylation solution and perform deacetylation treatment in a ventilated place for 12 hours. After treatment, dry them in a fume hood to obtain the hydrophilic membrane. The deacetylation solution is a 0.1-0.5 mol / L sodium hydroxide solution. S3: Stack the three prepared hydrophilic membranes together in an alternating pattern, soak them in water, clamp them with a hollow rubber sheet, and then fix them in a hollow container to obtain the desired oil-water separation column.

[0023] Specifically, the processing flow of an oil-water separator includes the following steps: S1: The wastewater sample is pumped into the oil-water separation column through an external water pump. After the wastewater is naturally filtered through the membrane by gravity, the mineral oil and emulsified oil in the water can be quickly separated from the water. S2: Thanks to the hydrophilicity of the membrane, mineral oil and emulsion cannot be filtered through the membrane and are well retained, achieving preliminary purification of wastewater.

[0024] Specifically, the photocatalytic quartz column is prepared using the following method, including the following steps: S1: Dissolve 5 wt% polyacrylonitrile powder in acetone or dimethyl sulfoxide solution at a volume ratio of 1:1, stir evenly, add 3 wt% modified g-C3N4 powder, and then sonicate for 15 min to disperse evenly and remove air bubbles. S2: Then take 5 mL of spinning solution and use electrospinning technology to spin single needle blends on baking paper at a speed of 0.15 mL / min under voltages of 22 kV and -2.5 kV. S3: Then cut the membrane into a standard size of 3x3cm, sprinkle it directly into the quartz column at a concentration of 1g / L, and then attach a stirrer to the top to obtain the desired photocatalytic quartz column.

[0025] Specifically, the preparation method of the modified g-C3N4 powder used in the photocatalytic quartz column includes the following steps: S1: Mix commercially available industrial-grade g-C3N4 powder with NaCl, KCl and LiCl in a uniform mass ratio of 5:3:1:1; S2: Subsequently, the mixed powder is placed in a tube furnace and heated to 550°C at a rate of 1.5°C / min under argon conditions. It is then held at this temperature for 5 hours and allowed to cool naturally.

[0026] Specifically, the processing flow of photocatalytic quartz columns includes the following steps: S1: The pre-treated wastewater, which is free of obvious oil stains, is pumped into the photocatalytic quartz column from the lower interface. After the separation membrane-based catalyst is fully floated, the stirrer is turned on and the 330W xenon lamps on both sides are turned on for irradiation. S2: The catalytically treated wastewater is extracted from the top and circulated for 1.5-3 hours to complete the catalytic decontamination.

[0027] Specifically, the adsorption column is prepared using the following method, including the following steps: S1: Dissolve 5 wt% chitosan / polyvinyl alcohol mixed powder in 90 vol% acetic acid solution, wherein the mass ratio of chitosan to polyvinyl alcohol is 1:9; S2: After the chitosan / polyvinyl alcohol mixed powder is evenly mixed, take 10 mL of spinning solution and use electrospinning technology to spin single needles on baking paper at a voltage of 23 kV and a speed of 0.25 mL / min. S3: Take three standard-sized chitosan-based fiber membrane sheets, stack them in an alternating manner, soak them in water, clamp them with hollow rubber sheets, and then fix them in a hollow container to obtain an adsorption column; S4: To ensure removal efficiency and purification depth, a single adsorption column needs to be loaded with 3-5 standard chitosan-based fiber membrane sheets.

[0028] Specifically, the adsorption column processing flow includes the following steps: S1: The purified wastewater with low oil and COD content, which has undergone deep treatment by oil-water separation and photocatalysis, is slowly pumped into the column cavity from the interface above the membrane column, so that the wastewater can fully contact and be naturally filtered by 3-5 layers of standard chitosan-based fiber membrane sheets. S2: Extract the adsorption-treated wastewater from the bottom and circulate it for 1.5-3 hours to complete the adsorption purification.

[0029] Specifically, the adsorption column treatment process includes the following elution steps for heavy metal pollutants: S1: Mix the prepared 0.1mol / L thiourea and 0.2mol / L HCl in a volume ratio of 1:1. After stirring evenly, immerse the chitosan-based fiber membrane containing heavy metals such as Cu and Pb into it and soak for 15-30 minutes to complete the washing of 85-93% of the adsorbed heavy metals. S2: Then, rinse the de-washed chitosan-based fiber membranes 2-3 times with water and alcohol respectively, and let them air dry in a fume hood to achieve membrane recycling.

[0030] The present invention will be further described below through specific embodiments.

[0031] Example 1: The wastewater treated in this embodiment was taken from a chemical fiber dyeing company, and the water quality indicators were: COD=450mg / L, NH4+ 4+- N=32mg / L, SS=127mg / L and it shows a distinct blue color.

[0032] The processing procedure includes the following steps: Step 1: Slowly pump 100L of wastewater from chemical fiber dyeing collected on-site into an oil-water separation column with a single-layer hydrophilic membrane volume of 1L at a rate of 150mL / min. After it has been completely filtered naturally, the water can be purified in its primary stage. At this point, the water's COD was 407 mg / L, SS was 9 mg / L, and NH3 was... 4+- N=29mg / L, no significant change, but color intensity decreased slightly.

[0033] Step 2: The pre-purified water is passed into a 1.5L photocatalytic quartz column loaded with a 1.95g high-efficiency photocatalytic membrane at a rate of 200mL / min. After the photocatalytic membrane is completely submerged, the water is continuously circulated and stirred at a rate of 50mL / min and a rotation speed of 100r / min. The water is then further purified by simulating sunlight using a 330W xenon lamp. The time for circulation, stirring, and xenon lamp illumination is 1.5h. At this point, the water's COD was 24.7 mg / L, SS was 7 mg / L, and NH3 was... 4+- N=14.7mg / L, the solution has no obvious color, which meets the emission standards.

[0034] The preparation method of the oil-water separation column in the above process includes the following steps: S1: Dissolve 8.54g of cellulose acetate in 150mL of acetic acid or dichloromethane solution with a volume ratio of 2:1 to prepare a spinning solution; take 8mL of the spinning solution and use electrospinning technology to continuously spin single needles three times on baking paper at voltages of 18kV and -2.5kV, under environmental conditions of 50% humidity and 25℃, with a feed speed of 0.35mL / min and a receiver rotation speed of 25r / min.

[0035] S2: Take three 20x20cm membranes and place them in plastic petri dishes. Dissolve 2g NaOH in 100mL deionized water, stir well, and then slowly pour it into the petri dishes to completely immerse the membranes. Perform deacetylation treatment in a ventilated place for 12 hours. After treatment, wash with water and alcohol three times each, and dry in a fume hood to obtain the desired hydrophilic membrane.

[0036] S3: Stack the three prepared hydrophilic membranes together in an alternating pattern, soak them in water, clamp them with a hollow rubber sheet, exposing about 1.5 dm2 of the hydrophilic membrane contact area, and then fix them in a hollow container to obtain the desired oil-water separation column.

[0037] The preparation method of the photocatalytic quartz column in the above process includes the following steps: S1: Dissolve 4.72g of polyacrylonitrile powder in 100mL of acetone / dimethyl sulfoxide solution (1:1 by volume), stir until homogeneous, add 2.971g of modified g-C3N4 powder, and then sonicate for 15min to disperse evenly and remove air bubbles; take 5mL of spinning solution and electrospin on baking paper at 22kV and -2.5kV voltages, 50% humidity and 25℃, with a feed rate of 0.15mL / min and a receiver rotation speed of 25r / min.

[0038] S2: Then cut the membrane into a standard size of 3x3cm, sprinkle it directly into the quartz column at a concentration of 1.57g, and then attach a spiral stirrer to the top to obtain the desired photocatalytic quartz column.

[0039] Example 2: The wastewater treated in this embodiment was taken from a smelting enterprise, and the water quality indicators were: Cu=25.47mg / L, Pb=12.25mg / L, Ni=31.47mg / L, SS=224mg / L, and mineral oil=1.2g / L.

[0040] The processing procedure includes the following steps: Step 1: Slowly pump 100L of smelting wastewater collected on-site at a rate of 100mL / min into an oil-water separation column with a single-layer hydrophilic membrane volume of 1L. After it has been completely filtered naturally, the primary purification of the water body can be achieved. At this point, the water concentrations are: Cu = 22.29 mg / L, Pb = 11.17 mg / L, Ni = 29.89 mg / L, SS = 10.2 mg / L, and mineral oil = 17.9 mg / L.

[0041] Step 2: Pump the primary purified wastewater into an adsorption column with a volume of 3L loaded with 5 layers of chitosan-based fiber membrane at a rate of 75mL / min, and circulate and filter the water for 3 hours. At this point, the water concentrations were Cu = 1.72 mg / L, Pb = 0.197 mg / L, Ni = 1.43 mg / L, SS = 1.83 mg / L, and mineral oil = 7.91 mg / L, indicating a significant decrease in pollutant concentrations.

[0042] In the above process, the preparation method of the oil-water separation column is the same as in Example 1; The above process includes the following steps in the preparation of the adsorption column: S1: Add 1.045g of chitosan and 9.402g of polyvinyl alcohol to 100mL of 90vol% acetic acid solution, mix well, take 10mL of spinning solution, and use electrospinning technology to spin single needles on baking paper at a driving speed of 0.25mL / min and a receiver rotation speed of 25r / min under the environmental conditions of 23kV voltage, 75% humidity and 25℃. Repeat the above process 5 times.

[0043] S2: Take three standard-sized chitosan-based fiber membrane sheets of 25x25cm, stack them in an alternating manner, soak them in water, clamp them with hollow rubber sheets, expose a 2.5dm2 contact area in the center, and then fix them in a hollow container. To ensure removal efficiency and purification depth, the adsorption column needs to be loaded with 5 standard chitosan-based fiber membrane sheets.

[0044] Example 3: This implementation is an application extension for systemic wastewater treatment. Samples were taken from a livestock farm, and the water quality indicators were: COD = 798 mg / L, NH3... 4+- N=127mg / L, TP=12.78, SS=347mg / L, Zn-8.97mg / L.

[0045] The processing procedure includes the following steps: Step 1: Slowly pump 50 mL of aquaculture wastewater collected on-site at a rate of 150 mL / min into an oil-water separation column with a single-layer hydrophilic membrane volume of 1 L. After it has been completely filtered naturally, the primary purification of the water body can be achieved. At this time, COD = 428 mg / L, NH... 4+- N=106mg / L, TP=10.74mg / L, SS=56mg / L, Zn=8.12mg / L.

[0046] Step 2: The preliminarily purified water is passed into a 1.5L photocatalytic quartz column containing a 2.74g high-efficiency photocatalytic membrane at a rate of 200mL / min. After the photocatalytic membrane is completely submerged, the water is continuously circulated and stirred at a rate of 50mL / min and a rotation speed of 100r / min. A 330W xenon lamp is used to simulate sunlight for further purification of the water. The circulation, stirring, and xenon lamp illumination time is 3 hours. At this time, COD=97mg / L, NH4+-N=78mg / L, TP=8.82mg / L, SS=52mg / L, and Zn=6.92mg / L.

[0047] Step 3: Pump the primary purified wastewater into an adsorption column with a volume of 3L loaded with 5 layers of chitosan-based fiber membrane at a rate of 75mL / min, and circulate and filter the water for 3 hours. At this time, COD = 79 mg / L, NH... 4+- With N=68mg / L, TP=7.98mg / L, SS=19mg / L, and Zn=0.78mg / L, it has a significant effect.

[0048] In the above process, the preparation methods of the oil-water separation column and the photocatalyst are the same as in Example 1; The preparation method of the adsorption column in the above process is the same as in Example 2.

[0049] Comparative Example 1: For Example 1, instead of using an oil-water separation column for pretreatment, a photocatalytic quartz column was used for catalytic decontamination, with other conditions remaining unchanged; Results: COD = 179 mg / L, NH 4+- N=28mg / L, SS=101mg / L, the solution is slightly blue.

[0050] Comparative Example 2: For Example 1, instead of using an oil-water separation column for pretreatment, a polyacrylonitrile membrane with modified g-C3N4 was directly used for catalytic reaction, with other conditions remaining unchanged; Results: COD = 157 mg / L, NH 4+- N=27.9mg / L, SS=72mg / L, the solution is slightly blue.

[0051] Comparative Example 3: For Example 2, instead of using an oil-water separation column for pretreatment, a photocatalytic quartz column was used for adsorption and purification, while other conditions remained unchanged. Results: Cu = 8.19 mg / L, Pb = 5.928 mg / L, Ni = 10.11 mg / L, SS = 178 mg / L, and mineral oil = 1.07 g / L in the water.

[0052] Comparative Example 4: For Example 2, instead of using an oil-water separation column for pretreatment, chitosan-based fiber membranes were used for adsorption and purification, with stirring at 100 r / min and other adjustments kept the water volume unchanged. Results: Cu=7.87mg / L, Pb=5.287g / L, Ni=8.17mg / L, SS=76mg / L, mineral oil=12.88mg / L.

[0053] This invention comprises three core processes: "hydrophilic interception of oil pollution," "catalytic degradation of organic matter," and "adsorbent removal of heavy metals." The process is simple and streamlined, significantly reducing construction investment and operating costs while ensuring excellent effluent quality. Furthermore, it achieves a harmonious balance between the economic and environmental benefits of wastewater treatment.

[0054] This invention has the potential for resource recycling and pollution resistance, and significantly reduces the replacement frequency of membrane materials and the operating cost of wastewater treatment. This makes it more likely that this series of membrane technologies will move out of the laboratory and achieve more efficient and economical green wastewater treatment, with broad market application prospects.

[0055] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A method for treating complex industrial wastewater based on a novel separation membrane technology, characterized in that, Includes the following steps: Step 1: Slowly pump the wastewater into an oil-water separation column loaded with a single layer of hydrophilic membrane for simple single-pass filtration. After filtration, the water is preliminarily purified. Step 2: Continue to pass the pre-purified water into a photocatalytic quartz column loaded with a high-efficiency photocatalytic membrane, and continue to perform circulation filtration and illumination to complete the further purification of the water. The photocatalytic membrane is a single sheet of modified g-C3N4 polyacrylonitrile membrane with no risk of metal leaching. The circulation filtration time and the illumination time of the 330W xenon lamp are both 1-2 hours. Step 3: Pass the further treated wastewater into an adsorption column loaded with chitosan-based fiber membrane sheets for circulating filtration; wherein, the standard chitosan-based fiber membrane sheet is composed of 3 standard chitosan-based fiber membrane sheets fixed by die casting, and 3-5 standard chitosan-based fiber membrane sheets need to be loaded in a single adsorption column; the circulation filtration time is 1.5-3 hours.

2. The method for treating complex industrial wastewater based on novel separation membrane technology according to claim 1, characterized in that, The oil-water separation column is prepared using the following method, including the following steps: S1: Dissolve 5 wt% cellulose acetate in a solution with a volume ratio of 2:1 acetic acid / dichloromethane to prepare a spinning solution; take 8 mL of the spinning solution and spin it on baking paper using electrospinning technology at a voltage of 18 kV and -2.5 kV and a speed of 0.35 mL / min. S2: Based on the actual size of the membrane column, take 3 standard-sized membrane sheets and place them in plastic petri dishes. Then, slowly pour in an appropriate amount of deacetylation solution and perform deacetylation treatment in a ventilated place for 12 hours. After treatment, dry them in a fume hood to obtain the hydrophilic membrane. The deacetylation solution is a 0.1-0.5 mol / L sodium hydroxide solution. S3: Stack the three prepared hydrophilic membranes together in an alternating pattern, soak them in water, clamp them with a hollow rubber sheet, and then fix them in a hollow container to obtain the desired oil-water separation column.

3. The method for treating complex industrial wastewater based on novel separation membrane technology according to claim 1, characterized in that, The processing flow of the oil-water separation column includes the following steps: S1: The wastewater sample is pumped into the oil-water separation column through an external water pump. After the wastewater is naturally filtered through the membrane by gravity, the mineral oil and emulsified oil in the water can be quickly separated from the water. S2: Thanks to the hydrophilicity of the membrane, mineral oil and emulsion cannot be filtered through the membrane and are well retained, achieving preliminary purification of wastewater.

4. The method for treating complex industrial wastewater based on novel separation membrane technology according to claim 1, characterized in that, The photocatalytic quartz column is prepared by the following method, including the following steps: S1: Dissolve 5 wt% polyacrylonitrile powder in acetone or dimethyl sulfoxide solution at a volume ratio of 1:1, stir evenly, add 3 wt% modified g-C3N4 powder, and then sonicate for 15 min to disperse evenly and remove air bubbles. S2: Then take 5 mL of spinning solution and use electrospinning technology to spin single needle blends on baking paper at a speed of 0.15 mL / min under voltages of 22 kV and -2.5 kV. S3: Then cut the membrane into a standard size of 3x3cm, sprinkle it directly into the quartz column at a concentration of 1g / L, and then attach a stirrer to the top to obtain the desired photocatalytic quartz column.

5. The method for treating complex industrial wastewater based on novel separation membrane technology according to claim 4, characterized in that, The preparation method of the modified g-C3N4 powder used in the photocatalytic quartz column includes the following steps: S1: Mix commercially available industrial-grade g-C3N4 powder with NaCl, KCl and LiCl in a uniform mass ratio of 5:3:1:1; S2: Subsequently, the mixed powder is placed in a tube furnace and heated to 550°C at a rate of 1.5°C / min under argon conditions. It is then held at this temperature for 5 hours and allowed to cool naturally.

6. The method for treating complex industrial wastewater based on novel separation membrane technology according to claim 5, characterized in that, The processing steps for the photocatalytic quartz column include the following: S1: The pre-treated wastewater, which is free of obvious oil stains, is pumped into the photocatalytic quartz column from the lower interface. After the separation membrane-based catalyst is fully floated, the stirrer is turned on and the 330W xenon lamps on both sides are turned on for irradiation. S2: The catalytically treated wastewater is extracted from the top and circulated for 1.5-3 hours to complete the catalytic decontamination.

7. The method for treating complex industrial wastewater based on novel separation membrane technology according to claim 1, characterized in that, The adsorption column is prepared by the following method, including the following steps: S1: Dissolve 5 wt% chitosan / polyvinyl alcohol mixed powder in 90 vol% acetic acid solution, wherein the mass ratio of chitosan to polyvinyl alcohol is 1:9; S2: After the chitosan / polyvinyl alcohol mixed powder is evenly mixed, take 10 mL of spinning solution and use electrospinning technology to spin single needles on baking paper at a voltage of 23 kV and a speed of 0.25 mL / min. S3: Take three standard-sized chitosan-based fiber membrane sheets, stack them in an alternating manner, soak them in water, clamp them with hollow rubber sheets, and then fix them in a hollow container to obtain an adsorption column; S4: To ensure removal efficiency and purification depth, a single adsorption column needs to be loaded with 3-5 standard chitosan-based fiber membrane sheets.

8. The method for treating complex industrial wastewater based on novel separation membrane technology according to claim 7, characterized in that, The processing procedure for the adsorption column includes the following steps: S1: The purified wastewater with low oil and COD content, which has undergone deep treatment by oil-water separation and photocatalysis, is slowly pumped into the column cavity from the interface above the membrane column, so that the wastewater can fully contact and be naturally filtered by 3-5 layers of standard chitosan-based fiber membrane sheets. S2: Extract the adsorption-treated wastewater from the bottom and circulate it for 1.5-3 hours to complete the adsorption purification.

9. The method for treating complex industrial wastewater based on novel separation membrane technology according to claim 8, characterized in that, The processing flow of the adsorption column includes the following elution steps for heavy metal pollutants: S1: Mix the prepared 0.1mol / L thiourea and 0.2mol / L HCl in a volume ratio of 1:

1. After stirring evenly, immerse the chitosan-based fiber membrane containing heavy metals such as Cu and Pb into it and soak for 15-30 minutes to complete the washing of 85-93% of the adsorbed heavy metals. S2: Then, rinse the de-washed chitosan-based fiber membranes 2-3 times with water and alcohol respectively, and let them air dry in a fume hood to achieve membrane recycling.