Method for treating low-concentration glutaraldehyde wastewater

Abstract

The invention provides a treatment method of low-concentration glutaraldehyde wastewater, and belongs to the technical field of wastewater treatment. The method comprises the following steps: adjusting the pH value of low-concentration glutaraldehyde-containing wastewater generated by cleaning equipment and pipelines in a glutaraldehyde production workshop to weak acidity or neutrality, filtering to remove mechanical impurities, and treating by a reverse osmosis system to respectively obtain a concentrated solution and a penetrating fluid. The penetrating fluid does not contain glutaraldehyde or other impurities influencing the quality of a glutaraldehyde product, and can be used as water for industrial production of glutaraldehyde. When the content of glutaraldehyde in the concentrated solution reaches 25%, the concentrated solution can be directly sold as a product. The method for treating the low-concentration glutaraldehyde wastewater is simple in process, low in energy consumption, high in separation efficiency and low in cost.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, and particularly relates to a method for treating low-concentration glutaraldehyde wastewater. Background Art

[0002] Glutaraldehyde is widely used in the fields of medical care, petrochemicals, leather tanning, papermaking auxiliaries, etc. Because of its strong bactericidal effect under weakly alkaline conditions, it is also used as a broad-spectrum disinfectant. The methods for preparing glutaraldehyde in the prior art include the pyridine method, the pyran method, the polyol oxidation method, the cyclopentene oxidation method and the glutaric acid reduction method. However, the industrial methods for producing glutaraldehyde are almost all pyran methods. In the production process of glutaraldehyde, a considerable amount of low-concentration (glutaraldehyde mass percentage ≤4%) glutaraldehyde wastewater will be generated during the cleaning of workshop equipment before and after operation. Since glutaraldehyde is biologically toxic, especially directly toxic to aquatic organisms, the median lethal concentration (LC50) for aquatic organisms is 2.5-3.5. 50 ) is 3~56ppm. Therefore, wastewater containing glutaraldehyde cannot be discharged directly into the environment.

[0003] In the prior art, there are several methods for treating wastewater containing glutaraldehyde: (1) adding wastewater containing glutaraldehyde as product preparation water to the finished glutaraldehyde product; (2) using chemical reagents for treatment and then outsourcing for disposal; (3) using a distillation tower to separate and recover glutaraldehyde from wastewater containing glutaraldehyde. In method (1), since the wastewater itself contains a lot of impurities, adding them to the finished glutaraldehyde product will significantly reduce the product quality. Therefore, this method is not suitable for the production of high-quality glutaraldehyde. In method (2), since glutaraldehyde has a broad spectrum of bactericidal properties and cannot be directly treated by biochemical methods, it is not accepted by many sewage treatment plants; it is necessary to specifically remove glutaraldehyde before using biochemical methods for treatment, which increases the treatment cost and the salt content of the sewage. In method (3), when enriching low-concentration glutaraldehyde-containing wastewater, the energy consumption is extremely high, and glutaraldehyde will azeotrope with water at low concentrations, resulting in a poor separation effect. At the same time, since glutaraldehyde rapidly undergoes self-polymerization reaction at high temperature, the quality of the product separated by distillation is poor. Summary of the invention

[0004] Based on the above technical problems, the present invention provides a method for treating low-concentration glutaraldehyde wastewater. The method is carried out at room temperature, has a simple process, high separation efficiency, low energy consumption, and after the steps of adjusting pH, primary filtration, secondary filtration and reverse osmosis system treatment, the obtained permeate reaches the standard of "Purified Water" in Part II of the 2020 edition of the Pharmacopoeia of the People's Republic of China, and can be directly used as process water.

[0005] In order to achieve the above object, the present invention specifically adopts the following technical solutions: A method for treating low-concentration glutaraldehyde wastewater comprises the following steps: S1. Adding a pH regulator to wastewater containing glutaraldehyde to adjust the pH to weak acidity or neutrality to obtain a mixed solution A; the mass percentage of glutaraldehyde in the wastewater is ≤4%; S2, filtering the mixed solution A; S3, the filtrate obtained in step S2 is treated by a reverse osmosis system, and the permeate is used as water for glutaraldehyde industrial production.

[0006] In some preferred embodiments of the present invention, the pH adjuster is sodium hydroxide, potassium hydroxide, sodium bicarbonate, sodium carbonate, phosphoric acid, phosphate or formic acid.

[0007] In some preferred embodiments of the present invention, the pH is adjusted to 6-7 in step S1.

[0008] In some preferred embodiments of the present invention, the mixed solution A in step S2 is first filtered through a synthetic fiber filter cloth and then filtered through a precision filter.

[0009] In some further preferred embodiments of the present invention, the synthetic fiber filter cloth has a specification of 800-1500 meshes.

[0010] In some further preferred embodiments of the present invention, the pore size of the precision filter is 0.5 μm.

[0011] In some preferred embodiments of the present invention, the reverse osmosis membrane of the reverse osmosis system is made of polyamide.

[0012] In some preferred embodiments of the present invention, the pore size of the reverse osmosis membrane of the reverse osmosis system is 0.1-1.5 nm.

[0013] In some preferred embodiments of the present invention, the processing pressure of the reverse osmosis system is 4.0-6.0 MPa, and the processing speed is 2-10 m / s. 3 / sky.

[0014] In some preferred embodiments of the present invention, the reverse osmosis system is a multi-stage reverse osmosis membrane series system.

[0015] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: (1) The method of the present invention is used to treat low-concentration (glutaraldehyde mass percentage ≤ 4%) glutaraldehyde wastewater generated by cleaning the floor, equipment, and pipelines in a glutaraldehyde production workshop. The process is simple and the purpose of efficiently separating glutaraldehyde can be achieved at room temperature. The recovery rate of glutaraldehyde is at least 96%.

[0016] (2) The treated permeate does not contain glutaraldehyde or has a very low glutaraldehyde content, and does not contain other impurities that affect the quality of the glutaraldehyde product. Therefore, it can be used as water for the industrial production of glutaraldehyde, saving water resources and reducing the cost of wastewater treatment. At the same time, it avoids the problem of product quality degradation caused by direct reuse of wastewater before treatment. It can also achieve the purpose of self-circulating process without sewage output.

[0017] (3) Compared with the prior art, the treatment method of the present invention has only electricity costs and a small amount of pH adjuster raw material costs. It does not require high-temperature distillation or outsourcing, and does not require a large amount of labor costs, which significantly reduces the treatment cost of low-concentration glutaraldehyde wastewater.

[0018] (4) After treatment by the method of the present invention, when the recovered glutaraldehyde content reaches more than 25wt%, it can be directly sold as a product. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The figure is a flow chart of the main equipment used in the present invention to treat low-concentration glutaraldehyde wastewater.

[0020] In the figure: 1. Collection tank; 2. Storage tank; 3. Circulation pump; 4. Primary coarse filter; 5. High-pressure pump; 6. Precision filter; 7. Reverse osmosis system; 8. Product storage tank; 9. Water tank; 10. Pressure relief valve. DETAILED DESCRIPTION

[0021] The following content is combined with the embodiments to clearly and completely describe the technical solution of the present application so that those skilled in the art can fully understand the present application. Obviously, the described embodiments are only some preferred embodiments of the present application, rather than all embodiments. Any equivalent transformation or substitution made to the following implementation modes by those of ordinary skill in the art without creative work belongs to the protection scope of the present application.

[0022] In the following examples, the detection of glutaraldehyde in the concentrate was carried out with reference to the content determination method of "Concentrated Glutaraldehyde Solution" in Part II of the 2020 edition of the Pharmacopoeia of the People's Republic of China. The detection of glutaraldehyde content in the treated permeate was carried out with reference to the method in "3204 Glutaraldehyde Residue Determination Method" in Part IV of the 2020 edition of the Pharmacopoeia of the People's Republic of China.

[0023] The specific embodiment of the present invention provides a method for treating low-concentration glutaraldehyde wastewater, comprising the following steps: S1. Add a pH regulator to the wastewater containing glutaraldehyde generated by cleaning the floor, various equipment and pipelines in the glutaraldehyde production workshop, adjust the pH to 6-7, and obtain a mixed solution A; the mass percentage of glutaraldehyde in the wastewater is ≤4%; S2, the mixed solution A is firstly filtered through a synthetic fiber filter cloth with a mesh size of 800-1500 to remove mechanical impurities, and the obtained primary filtrate is filtered through a precision filter with a pore size of 0.5-1.0 μm to obtain a secondary filtrate; S3, the secondary filtrate obtained in step S2 is treated by a reverse osmosis system at a treatment pressure of 4.0-6.0 MPa and a treatment speed of 2-10 m 3 / day, and the permeate is used as water for the industrial production of glutaraldehyde.

[0024] In some specific embodiments, the concentrated solution obtained in step S3 has a glutaraldehyde content of more than 25 wt % and can be directly sold as a product.

[0025] In some specific embodiments, the reverse osmosis system in step S3 uses a polyamide reverse osmosis membrane.

[0026] In some specific embodiments, the reverse osmosis system in step S3 is a single-stage reverse osmosis membrane system.

[0027] In some specific embodiments, the reverse osmosis system in step S3 is a multi-stage reverse osmosis membrane parallel system. For example, the reverse osmosis system is a three-stage reverse osmosis membrane parallel system.

[0028] In some specific embodiments, the reverse osmosis system in step S3 is a multi-stage reverse osmosis membrane series system. For example, the reverse osmosis system is a two-stage, three-stage, or four-stage reverse osmosis membrane series system.

[0029] The following is a more detailed description of the method for treating low-concentration glutaraldehyde wastewater provided in the present invention in conjunction with the equipment flow chart.

[0030] Example 1 like Figure 1 As shown, a method for treating low-concentration glutaraldehyde wastewater comprises the following steps: S1. 6542 kg of wastewater containing glutaraldehyde (the mass percentage of glutaraldehyde is about 4%) generated by cleaning the floor, various equipment and pipelines in the glutaraldehyde production workshop is transported to the collection pool 1 through the collection pipeline. The pH adjuster (800 g of sodium hydroxide is prepared into a 50% aqueous solution with pure water or the above-mentioned collected wastewater) stored in the storage tank 2 is transported to the collection pool 1, and the liquid in the collection pool 1 is circulated and transported by the circulation pump 3 until it is mixed, and the pH of the wastewater is adjusted to 6.9 to obtain a mixed solution A.

[0031] S2. Filter the mixed liquid A through a primary coarse filter 4 (filter material is 1500 mesh polypropylene synthetic fiber filter cloth) to remove mechanical impurities, and the obtained primary filtrate is transported to a precision filter 6 (filter element material is polypropylene) with a pore size of 0.8 μm through a high-pressure pump 5 for a second filtration to obtain a secondary filtrate.

[0032] S3, the secondary filtrate is transported to the reverse osmosis system 7 through a pipeline, and is treated in three stages in series by the same high-pressure reverse osmosis membrane (8040 polyamide spiral reverse osmosis membrane with a pore size of 1.0 nm), with a filtration pressure of 5.8 MPa and a treatment speed of 6 m / s. 3 / day, the concentrated liquid obtained is transported to the product storage tank 8, and the permeate obtained is transported to the water tank 9. In order to protect the reverse osmosis system 7, a pressure relief valve 10 is provided on the pipeline between the precision filter 6 and the reverse osmosis system 7. During the wastewater treatment process, the pressure relief valve 10 is in a normally open state. When the pressure on the pipeline is too high, the pressure relief valve 10 is damaged first to prevent the wastewater from continuing to enter the reverse osmosis system 7. In this embodiment, a total of 1006 kg of concentrated liquid with a glutaraldehyde mass percentage of 25.2% (glutaraldehyde recovery rate of 96.9%) and about 5.6 m 3 Permeate. After testing, no glutaraldehyde was detected in the permeate, and the conductivity was 2.0μS / cm (20°C), which meets the standards for purified water in Part II of the 2020 edition of the Pharmacopoeia of the People's Republic of China.

[0033] Example 2 like Figure 1 As shown, a method for treating low-concentration glutaraldehyde wastewater comprises the following steps: S1. 983.2 kg of wastewater containing glutaraldehyde (glutaraldehyde mass percentage of 0.5%) generated by cleaning the floor, various equipment and pipelines in the glutaraldehyde production workshop is transported to the collection pool 1 through the collection pipeline. The pH adjuster (85wt% phosphoric acid) stored in the storage tank 2 is transported to the collection pool 1, and the liquid in the collection pool 1 is circulated by the circulation pump 3 until it is mixed, and the pH of the wastewater is adjusted to 6.1 to obtain a mixed solution A.

[0034] S2. Filter the mixed liquid A through a primary coarse filter 4 (filter material is 800-mesh nylon synthetic fiber filter cloth) to remove mechanical impurities, and the obtained primary filtrate is transported to a precision filter 6 (filter element material is ceramic sintered material) with a pore size of 0.5 μm through a high-pressure pump 5 for a second filtration to obtain a secondary filtrate.

[0035] S3, the secondary filtrate is transported to the reverse osmosis system 7 through a pipeline, and is treated in three stages in series by the same high-pressure reverse osmosis membrane (8040 polyamide spiral reverse osmosis membrane with a pore size of 0.1 nm), with a filtration pressure of 6.0 MPa and a treatment speed of 10 m / s. 3 / day, the concentrated solution obtained is transported to the product storage tank 8, and the permeate obtained is transported to the water tank 9. In this embodiment, a total of 105.6 kg of concentrated solution with a glutaraldehyde mass percentage of 4.52% (glutaraldehyde recovery rate of 97.1%) and about 0.8 m 3 Permeate. After testing, no glutaraldehyde was detected in the permeate, and the conductivity was 1.4μS / cm (20°C), which meets the standards for purified water in Part II of the 2020 edition of the Pharmacopoeia of the People's Republic of China.

[0036] Example 3 like Figure 1 As shown, a method for treating low-concentration glutaraldehyde wastewater comprises the following steps: S1. 2731 kg of glutaraldehyde-containing wastewater (glutaraldehyde mass percentage of 2%) generated by cleaning various equipment in the glutaraldehyde production workshop is transported to the collection pool 1 through the collection pipeline. The pH adjuster (50 wt% sodium dihydrogen phosphate aqueous solution) stored in the storage tank 2 is transported to the collection pool 1, and the liquid in the collection pool 1 is circulated by the circulation pump 3 until it is mixed, and the pH of the wastewater is adjusted to 6.5 to obtain a mixed solution A.

[0037] S2. Filter the mixed liquid A through a primary coarse filter 4 (filter material is 1000 mesh polypropylene synthetic fiber filter cloth) to remove mechanical impurities, and the obtained primary filtrate is transported to a precision filter 6 (filter element material is polypropylene) with a pore size of 1.0 μm through a high-pressure pump 5 for a second filtration to obtain a secondary filtrate.

[0038] S3, the secondary filtrate is transported to the reverse osmosis system 7 through a pipeline, and is treated by a single-stage high-pressure reverse osmosis membrane (8040 polyamide spiral reverse osmosis membrane with a pore size of 1.5 nm), the filtration pressure is 4.0 MPa, and the processing speed is 2 m 3 / day, the concentrated solution obtained is transported to the product storage tank 8, and the permeate obtained is transported to the water tank 9. In this embodiment, a total of 336 kg of concentrated solution with a glutaraldehyde mass percentage of 15.6% (glutaraldehyde recovery rate is 96.0%) and about 2.4 m 3 Permeate. After testing, no glutaraldehyde was detected in the permeate, and the conductivity was 2.1μS / cm (20°C), which meets the standards for purified water in Part II of the 2020 edition of the Pharmacopoeia of the People's Republic of China.

[0039] Comparative Example 1 This comparative example provides a method for treating low-concentration glutaraldehyde wastewater, which is basically the same as the method in Example 3, except that in step S3, the secondary filtrate is transported to the reverse osmosis system 7 through a pipeline and treated with a single-stage 1812-200G cellulose acetate membrane at a filtration pressure of 1.2 MPa and a treatment speed of 2 m 3 / day, and finally only a small amount of concentrated liquid with a glutaraldehyde mass percentage of 8.2% was obtained. At the same time, the 1812 acetate fiber membrane and glutaraldehyde underwent a cross-linking reaction, resulting in clogging of the filter pores and an extremely low filtration rate; if the pressure was continued, the filter pipe joint would rupture and the reverse osmosis treatment could not be continued.

[0040] The above-described embodiments are only preferred embodiments of the present application and are not intended to limit the scope of protection of the present application. For any person skilled in the art, the present application may have various changes and modifications. Any simple equivalent changes and modifications made based on the scope of protection of the present application and the contents of the specification should be included in the scope of protection of the present application.

Claims

1. A method for treating low-concentration glutaraldehyde wastewater, characterized in that: The following steps are involved: S1. Adding a pH regulator to wastewater containing glutaraldehyde to adjust the pH to weak acidity or neutrality to obtain a mixed solution A; the mass percentage of glutaraldehyde in the wastewater is ≤4%; S2, filtering the mixed solution A; S3, the filtrate obtained in step S2 is treated by a reverse osmosis system, and the permeate is used as water for glutaraldehyde industrial production.

2. The method for treating low-concentration glutaraldehyde wastewater according to claim 1, characterized in that: The pH regulator is sodium hydroxide, potassium hydroxide, sodium bicarbonate, sodium carbonate, phosphoric acid, phosphate or formic acid.

3. The method for treating low-concentration glutaraldehyde wastewater according to claim 1, characterized in that: In step S1, the pH is adjusted to 6-7.

4. The method for treating low-concentration glutaraldehyde wastewater according to claim 1, characterized in that: In step S2, the mixed solution A is first filtered through a synthetic fiber filter cloth and then filtered through a precision filter.

5. The method for treating low-concentration glutaraldehyde wastewater according to claim 4, characterized in that: The specification of the synthetic fiber filter cloth is 800-1500 meshes.

6. The method for treating low-concentration glutaraldehyde wastewater according to claim 4, characterized in that: The pore size of the precision filter is 0.5-1.0 μm.

7. The method for treating low-concentration glutaraldehyde wastewater according to claim 1, characterized in that: The reverse osmosis membrane of the reverse osmosis system is made of polyamide; or / and the pore size of the reverse osmosis membrane of the reverse osmosis system is 0.1-1.5 nm.

8. The method for treating low-concentration glutaraldehyde wastewater according to claim 1, characterized in that: The processing pressure of the reverse osmosis system is 4.0~6.0MPa, and the processing speed is 2~10m 3 / sky.

9. The method for treating low-concentration glutaraldehyde wastewater according to claim 1, characterized in that: The reverse osmosis system is a multi-stage reverse osmosis membrane series system.

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