Treatment method of low-content crotonaldehyde wastewater

Abstract

The invention belongs to the technical field of crotonaldehyde wastewater treatment, and discloses a treatment method of low-content crotonaldehyde wastewater. The treatment method of the low-content crotonaldehyde wastewater comprises the following steps: S1, storing to-be-treated wastewater in a wastewater pool; s2, measuring the crotonaldehyde percentage content, the chemical oxygen demand and the water temperature in the to-be-treated wastewater in the wastewater pool, and adjusting according to measurement results; s3, adjusting the pH value of the wastewater to be treated, adding carbamide for reaction, and continuously monitoring the crotonaldehyde content in the wastewater; and S4, carrying out biochemical treatment on the treated wastewater to further reduce the content of pollutants in the wastewater. According to the technical scheme, the waste heat of the crotonaldehyde production wastewater is fully utilized to promote the reaction of crotonaldehyde and carbamide, so that the crotonaldehyde content in the wastewater is effectively reduced, the biotoxicity of crotonaldehyde to microorganisms is reduced, and other polluting substances can be continuously treated on the wastewater by adopting a cheap and effective microbiological method subsequently.

Description

Technical Field

[0001] The present application relates to the technical field of crotonaldehyde wastewater treatment, and in particular to a method for treating low-content crotonaldehyde wastewater. Background Art

[0002] Crotonaldehyde is a colorless or light yellow liquid with flammability and tear-inducing properties. When exposed to air or light, it gradually turns into a light yellow liquid and is oxidized to crotonic acid. It is an important organic synthesis intermediate used to make butyraldehyde, food preservative sorbic acid, synthetic resins, dyes, pesticides, mineral processing foaming agents, rubber antioxidants, etc. Crotonaldehyde is extremely toxic and has a strong irritating effect on human eyes and skin. If crotonaldehyde wastewater is directly discharged, even at a low concentration, it will cause serious pollution to the environment and pose a serious threat to organisms and humans.

[0003] Studies have found that due to the toxic effect of crotonaldehyde on microorganisms, even at low concentrations, it can significantly inhibit the growth and reproduction of microorganisms, resulting in a significant decrease in the treatment effect of microbial methods on chemical oxygen demand. Therefore, in order to effectively remove other pollutants in wastewater using microbial methods, it is necessary to first selectively remove or effectively reduce the crotonaldehyde content in the wastewater and effectively reduce the COD of the wastewater.

[0004] The treatment methods for crotonaldehyde wastewater in the prior art mainly include incineration and hydrolysis acidification. The incineration method has a better treatment effect, but the equipment investment and operating costs are extremely high. The incineration method has high requirements on the chemical properties of wastewater. Only when the organic waste liquid meets the chemical oxygen demand (COD) ≥ 100000 mg / L and the calorific value ≥ 10467 KJ / kg (2500 kcal / kg), the incineration method is more economical and reasonable. However, the calorific value of production wastewater with a low crotonaldehyde content is relatively low, and the operating cost of the incineration method is too high; in addition, if the salt content in the waste liquid is high, there are high requirements for the corrosion resistance of the refractory materials of the incinerator, which further increases the cost of the incineration process. The hydrolysis acidification method is recognized as an effective method for removing toxic organic pollutants and an ideal detoxification pretreatment method. It can only be effectively detoxified under low organic load conditions. Summary of the invention

[0005] In order to solve the above technical problems, a wastewater treatment method is developed for selectively removing crotonaldehyde in wastewater with a high temperature, a crotonaldehyde content range of 0-0.2wt%, and a chemical oxygen demand of 50000-120000 mg / L. The present application provides a method for treating low-content crotonaldehyde wastewater.

[0006] In a first aspect, the present application provides a method for treating low-content crotonaldehyde wastewater, comprising the following steps: S1. Mixing the waste liquid produced by preparing crotonaldehyde by solid base catalysis and storing it in a wastewater pool as wastewater to be treated; S2. Determine the percentage of crotonaldehyde, chemical oxygen demand and water temperature in the wastewater to be treated in the wastewater pool, and perform the next step of treatment on the wastewater to be treated according to the measurement results: when the percentage of crotonaldehyde is too low to be detected, the wastewater to be treated can be directly subjected to the next step of biochemical treatment to reduce the chemical oxygen demand of the wastewater to be treated; when the percentage of crotonaldehyde is higher than the set value, water can be added to the wastewater pool to make the percentage of crotonaldehyde in the wastewater to be treated meet the set value, and the water temperature of the wastewater to be treated is controlled for the next step of treatment; S3, adjusting the pH of the wastewater to be treated, adding carbonamide to the wastewater to be treated and stirring according to the percentage of crotonaldehyde obtained in step S2, and continuously monitoring the percentage of crotonaldehyde in the wastewater to be treated; S4. When the percentage of crotonaldehyde cannot be detected, the wastewater treated in step S3 is subjected to biochemical treatment to further reduce the content of pollutants in the wastewater and the chemical oxygen demand of the wastewater.

[0007] By adopting the above-mentioned technical scheme, solid base catalysis method prepares crotonaldehyde, and in a specific preparation method, hydrotalcite and the composite oxide after roasting thereof can be used as a carrier, and solid base catalyst is prepared by impregnation method loaded alkali metal. Containing acetaldehyde, acetic acid, 3-hydroxybutyraldehyde, 4-hydroxy-2-butanone, p-methylbenzaldehyde and other organic wastes in waste liquid, due to the toxic effect of crotonaldehyde on microorganisms, even in the case of low concentration, the growth and reproduction of microorganisms will also be significantly inhibited, resulting in a significant decrease in the treatment effect of microbiological method on chemical oxygen demand. Therefore, the waste heat of high temperature crotonaldehyde production wastewater is utilized in the present application to promote the reaction of crotonaldehyde and carbonamide, so as to reduce the biological toxicity of crotonaldehyde in waste water to microorganisms, and facilitate the subsequent method for treating wastewater using cheap and effective microbiological method.

[0008] Optionally, in step S1, the chemical oxygen demand value of the wastewater to be treated is 50,000-120,000 mg / L.

[0009] Optionally, in step S2, the set value of the crotonaldehyde percentage is 0.2wt%. When the crotonaldehyde percentage is lower than the set value, step S3 can be performed directly. When the crotonaldehyde percentage is higher than the set value, the crotonaldehyde percentage needs to be adjusted.

[0010] Optionally, in step S3, the pH of the wastewater to be treated is adjusted to 2-8.

[0011] Preferably, in step S3, the pH of the wastewater to be treated is adjusted to 2-3.

[0012] Preferably, in step S3, the pH of the wastewater to be treated is adjusted to 6-7.

[0013] By adopting the above technical scheme, the carbonic acid amide used in the present application, also known as urea, is an organic compound containing an amide group, and its molecular formula is CO(NH2)2. Crotonaldehyde is 2-butenal, and its chemical formula is C4H6O, and it has a suffocating irritating odor, and it is mainly used as a raw material for organic synthesis. The reaction of urea with butenal in a weakly acidic environment mainly produces Schiff base as a reaction product, which is formed by a series of reaction condensations of active carbonyl and amine compounds, and mainly forms C=N bonds through nucleophilic addition reactions. Urea first undergoes nucleophilic addition reaction with butenal to form an intermediate of α-hydroxylamine compounds, and then further dehydrates to form Schiff base. In this process, the amino group of urea attacks the carbonyl carbon atom of butenal as a nucleophilic reagent to complete the nucleophilic addition reaction.

[0014] Optionally, in step S3, when carbonamide is added to the wastewater, the wastewater temperature is 40-70°C.

[0015] Optionally, in step S3, when carbonamide is added to the wastewater, the amount of carbonamide added is 0.5-20 g / L.

[0016] Optionally, in step S3, when the percentage of crotonaldehyde in the wastewater to be treated is 0.15wt%, carbonamide is added to the wastewater, and the amount of carbonamide added is 0.5-3g / L.

[0017] In summary, the present invention includes at least one of the following beneficial technical effects: 1. The present application makes full use of the waste heat of crotonaldehyde production wastewater to promote the reaction of crotonaldehyde and carbonamide, thereby effectively reducing the crotonaldehyde content in the wastewater and reducing the biological toxicity of crotonaldehyde in the wastewater to microorganisms, which is conducive to the subsequent use of inexpensive and effective microbial methods to continue to treat other pollutants in the wastewater.

[0018] 2. The present application can directly treat the wastewater generated by the production of crotonaldehyde without the need for other pretreatment methods. The high temperature of the untreated wastewater actually promotes the reaction between crotonaldehyde and carbonamide. The wastewater treatment process of the present application is simple, does not require additional equipment, requires little investment, does not generate secondary pollution, has a short treatment time, and has a good treatment effect. DETAILED DESCRIPTION

[0019] The present application designs a method for treating low-content crotonaldehyde wastewater, comprising the following steps: S1. Mixing the waste liquid produced by preparing crotonaldehyde by solid base catalysis and storing it in a wastewater pool as wastewater to be treated; S2. Determine the percentage of crotonaldehyde, chemical oxygen demand and water temperature in the wastewater to be treated in the wastewater pool, and perform the next step of treatment on the wastewater to be treated according to the measurement results: when the percentage of crotonaldehyde is too low to be detected, the wastewater to be treated can be directly subjected to the next step of biochemical treatment to reduce the chemical oxygen demand of the wastewater to be treated; when the percentage of crotonaldehyde is higher than the set value, water can be added to the wastewater pool to make the percentage of crotonaldehyde in the wastewater to be treated meet the set value, and the water temperature of the wastewater to be treated is controlled for the next step of treatment; S3, adjusting the pH of the wastewater to be treated, adding carbonamide to the wastewater to be treated and stirring according to the percentage of crotonaldehyde obtained in step S2, and continuously monitoring the percentage of crotonaldehyde in the wastewater to be treated; S4. When the percentage of crotonaldehyde cannot be detected, the wastewater treated in step S3 is subjected to biochemical treatment to further reduce the content of pollutants in the wastewater and the chemical oxygen demand of the wastewater.

[0020] In step S3, the pH of the wastewater to be treated is adjusted to 2-3; or, in step S3, the pH of the wastewater to be treated is adjusted to 6-7.

[0021] In step S3, when the percentage of crotonaldehyde in the wastewater to be treated is 0.15wt%, carbonamide is added to the wastewater, and the amount of carbonamide added is 0.5-3g / L.

[0022] The technical problem solved by the present application is that due to the toxic effect of crotonaldehyde on microorganisms, even wastewater with a relatively low crotonaldehyde concentration cannot be directly treated with a microbial method or other low-cost biochemical treatment methods. Moreover, the calorific value of production wastewater with a relatively low crotonaldehyde content is relatively low, and it is not suitable for treatment by incineration, so it is necessary to selectively remove or effectively reduce the crotonaldehyde content in the wastewater and effectively reduce the COD of the wastewater. The present application makes full use of the waste heat of crotonaldehyde production wastewater to promote the reaction of crotonaldehyde and carbonamide, thereby effectively reducing the crotonaldehyde content in the wastewater, reducing the biological toxicity of crotonaldehyde in the wastewater to microorganisms, and is conducive to the subsequent use of inexpensive and effective microbial methods to continue to treat other pollutants in the wastewater.

[0023] The present application is further described in detail below in conjunction with specific embodiments.

[0024] Examples 1-6 The method for treating low-content crotonaldehyde wastewater in Example 1 comprises the following steps: S1. Mixing the waste liquid produced by preparing crotonaldehyde by solid base catalysis and storing it in a wastewater pool as wastewater to be treated; S2. The crotonaldehyde content, chemical oxygen demand and water temperature of the wastewater to be treated in the wastewater pool are measured. The percentage of crotonaldehyde in the wastewater to be treated is 0.15wt%, the chemical oxygen demand of the wastewater to be treated is 91123mg / L, and the temperature of the wastewater to be treated is about 50°C. It can be seen that the crotonaldehyde content, chemical oxygen demand and water temperature of the wastewater to be treated meet the conditions and do not need to be adjusted; S3, take 1L of the wastewater to be treated, adjust the pH of the wastewater to be treated to 2.0, add 0.5g of carbonamide to the solution, stir, and take samples every 2 hours to detect the percentage of crotonaldehyde and the chemical oxygen demand of the wastewater; S4. When the percentage of crotonaldehyde cannot be detected, the wastewater treated in step S3 is subjected to biochemical treatment to further reduce the content of pollutants in the wastewater and the chemical oxygen demand of the wastewater.

[0025] Example 2 is based on Example 1, except that in step S3 of Example 2, the amount of carbonamide added is changed to 1.0 g.

[0026] Example 3 is based on Example 1, except that in step S3 of Example 3, the amount of carbonamide added is changed to 1.5 g.

[0027] Example 4 is based on Example 1, except that in Example 4, the amount of carbonamide added in step S3 is changed to 2.0 g.

[0028] Example 5 is based on Example 1, except that in step S3 of Example 5, the amount of carbonamide added is changed to 2.5 g.

[0029] Example 6 is based on Example 1, except that in Example 6, the amount of carbonamide added in step S3 is changed to 3.0 g.

[0030] After adding carbonamide in step S3 in Example 1-6, samples were taken every 2 hours to detect the percentage content and chemical oxygen demand of crotonaldehyde. At the same time, after measurement, the wastewater in Example 1-6 also contained 0.22wt% acetaldehyde and 0.28wt% 4-hydroxy-2-butanone, and the contents of the above two substances were also monitored synchronously. The measurement results are shown in Table 1, Table 2 and Table 3.

[0031] Table 1 Monitoring of crotonaldehyde percentage in Examples 1-6 Table 2 Chemical oxygen demand (COD) monitoring in Examples 1-6 Table 3 Monitoring of acetaldehyde and 4-hydroxy-2-butanone content in Examples 1-6 By analyzing Tables 1, 2, and 3, it can be obtained that the treatment method of low-content crotonaldehyde wastewater in this application has a good effect on the selective removal of crotonaldehyde. On the one hand, the selective removal of crotonaldehyde is conducive to saving the amount of carbonamide used, and on the other hand, it can specifically remove the crotonaldehyde in the crotonaldehyde wastewater that is more toxic to microorganisms, so as to carry out the next step of biochemical treatment to remove other pollutants, which can reduce costs to the greatest extent. Under the condition of crotonaldehyde content of 0.15%, the carbonamide dosage of 0.5-3.0g / L can effectively remove crotonaldehyde and reduce the chemical oxygen demand in the wastewater to be treated, and the reagent dosage is small, which saves treatment costs.

[0032] Examples 7-12 The method for treating low-content crotonaldehyde wastewater in Example 7 comprises the following steps: S1. Mixing the waste liquid produced by preparing crotonaldehyde by solid base catalysis and storing it in a wastewater pool as wastewater to be treated; S2. The crotonaldehyde content, chemical oxygen demand and water temperature of the wastewater to be treated in the wastewater pool are measured. The percentage of crotonaldehyde in the wastewater to be treated is 0.12wt%, the chemical oxygen demand of the wastewater to be treated is 95320mg / L, and the temperature of the wastewater to be treated is about 60°C. It can be seen that the crotonaldehyde content, chemical oxygen demand and water temperature of the wastewater to be treated meet the conditions and do not need to be adjusted. S3, take 1L of the wastewater to be treated, adjust the pH of the wastewater to be treated to 3.0, add 2g of carbonamide to the solution, stir, and take samples every 2 hours to detect the percentage of crotonaldehyde and the chemical oxygen demand of the wastewater; S4. When the percentage of crotonaldehyde cannot be detected, the wastewater treated in step S3 is subjected to biochemical treatment to further reduce the content of pollutants in the wastewater and the chemical oxygen demand of the wastewater.

[0033] Example 8 is based on Example 7, except that: in Example 8, the pH of the wastewater to be treated is adjusted to about 4.0 before adding carbonamide in step S3.

[0034] Example 9 is based on Example 7, except that: in Example 9, the pH of the wastewater to be treated is adjusted to about 5.0 before adding carbonamide in step S3.

[0035] Example 10 is based on Example 7, except that: in Example 10, the pH of the wastewater to be treated is adjusted to about 6.0 before adding carbonamide in step S3.

[0036] Example 11 is based on Example 7, except that: in Example 11, the pH of the wastewater to be treated is adjusted to about 7.0 before adding carbonamide in step S3.

[0037] Example 12 is based on Example 7, with the difference that: in Example 12, the pH of the wastewater to be treated is adjusted to about 8.0 before adding carbonamide in step S3.

[0038] In Example 7-12, after adding carbonamide in step S3, samples were taken every 2 hours to detect the percentage of crotonaldehyde and chemical oxygen demand. The measurement results are shown in Table 4 and Table 2.

[0039] Table 4 Monitoring of crotonaldehyde percentage in Examples 7-12 Table 5 Chemical oxygen demand (COD) monitoring in Examples 7-12 By analyzing the data in Table 4 and Table 5, it can be obtained that in the method for treating low-content crotonaldehyde wastewater in the present application, carbonamide can have a very good removal effect on crotonaldehyde under acidic or neutral conditions, saving the cost of adjusting acid and alkali. By comparing Example 4 with Example 1, it can be obtained that the treatment effect is better under higher temperature conditions.

[0040] In summary, the present application can directly treat both high- and low-temperature crotonaldehyde wastewater, and can effectively and selectively remove crotonaldehyde in the wastewater within a wide pH range (pH 2-8), thereby reducing the chemical oxygen demand (COD). The wastewater treatment process of the present application is simple, requires little investment, does not cause secondary pollution, and has a short treatment time. It only takes half a day to reduce the crotonaldehyde content to an undetectable level, and the treatment effect is good.

[0041] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for treating low-content crotonaldehyde wastewater, characterized in that: The following steps are involved: S1. Mixing the waste liquid produced by preparing crotonaldehyde by solid base catalysis and storing it in a wastewater pool as wastewater to be treated; S2. Determine the percentage of crotonaldehyde, chemical oxygen demand and water temperature in the wastewater to be treated in the wastewater pool, and perform the next step of treatment on the wastewater to be treated according to the measurement results: when the percentage of crotonaldehyde is too low to be detected, the wastewater to be treated can be directly subjected to the next step of biochemical treatment to reduce the chemical oxygen demand of the wastewater to be treated; when the percentage of crotonaldehyde is higher than the set value, water can be added to the wastewater pool to make the percentage of crotonaldehyde in the wastewater to be treated meet the set value, and the water temperature of the wastewater to be treated is controlled for the next step of treatment; S3, adjusting the pH of the wastewater to be treated, adding carbonamide to the wastewater to be treated and stirring according to the percentage of crotonaldehyde obtained in step S2, and continuously monitoring the percentage of crotonaldehyde in the wastewater to be treated; S4. When the percentage of crotonaldehyde cannot be detected, the wastewater treated in step S3 is subjected to biochemical treatment to further reduce the content of pollutants in the wastewater and the chemical oxygen demand of the wastewater.

2. The method for treating low-content crotonaldehyde wastewater according to claim 1, characterized in that: In step S1, the chemical oxygen demand value of the wastewater to be treated is 50,000-120,000 mg / L.

3. The method for treating low-content crotonaldehyde wastewater according to claim 1, characterized in that: In the step S2, the set value of the crotonaldehyde percentage is 0.2wt%. When the crotonaldehyde percentage is lower than the set value, step S3 can be directly performed. When the crotonaldehyde percentage is higher than the set value, the crotonaldehyde percentage needs to be adjusted.

4. The method for treating low-content crotonaldehyde wastewater according to claim 1, characterized in that: In step S3, the pH of the wastewater to be treated is adjusted to 2-8.

5. The method for treating low-content crotonaldehyde wastewater according to claim 1, characterized in that: In the step S3, the pH of the wastewater to be treated is adjusted to 2-3; or, in the step S3, the pH of the wastewater to be treated is adjusted to 6-7.

6. The method for treating low-content crotonaldehyde wastewater according to claim 1, characterized in that: In step S3, when carbonamide is added to the wastewater, the temperature of the wastewater is 40-70°C.

7. The method for treating low-content crotonaldehyde wastewater according to claim 1, characterized in that: In the step S3, when carbonamide is added to the wastewater, the amount of carbonamide added is 0.5-20 g / L.

8. The method for treating low-content crotonaldehyde wastewater according to claim 1, characterized in that: In the step S3, when the percentage of crotonaldehyde in the wastewater to be treated is 0.15wt%, carbonamide is added to the wastewater, and the amount of carbonamide added is 0.5-3g / L.

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