Treatment method of vanillin wastewater

Abstract

The invention discloses a vanillin wastewater treatment method which comprises the following steps: introducing steam into wastewater for steam stripping to remove small molecules and volatile organic matters in the wastewater; the wastewater after steam stripping is subjected to Fenton oxidation treatment, macromolecular substances are decomposed, meanwhile, TOC of the wastewater is greatly reduced, and metal pollutants are removed; fenton oxidation produced water is subjected to sodium hypochlorite catalytic oxidation process treatment, residual organic matter in the wastewater is degraded into water and carbon dioxide, TOC, metal and other pollutants in the wastewater are reduced to the sea discharge standard, and finally sea discharge treatment is achieved. The wastewater produced in the vanillin production process can reach the sea discharge treatment standard, and the problems that the wastewater amount is large, pollutants are difficult to treat and the like are solved.

Description

Technical Field

[0001] The present invention relates to a method for treating vanillin wastewater, and in particular to a method for advanced treatment of vanillin wastewater, belonging to the field of environmental protection for industrial wastewater disposal. Background Art

[0002] Vanillin has the aroma of vanilla beans and a strong milk fragrance, and plays a role in enhancing and fixing the fragrance. Vanillin is divided into natural vanillin and synthetic vanillin. Natural vanillin refers to vanillin extracted from plants, which has a low yield and a high price and cannot meet the market demand. The raw material sources and production technologies of synthetic vanillin are stable, the supply is sufficient and the price is low. Synthetic vanillin accounts for 90% of the vanillin product market share. It is widely used in industries such as food, cosmetics, and medicine, and has a very wide application. It is one of the synthetic fragrance varieties with the largest global production. The annual consumption in the world market is 16,000 - 20,000 tons, and it has a broad market prospect.

[0003] The preparation methods of synthetic vanillin mainly include nearly 10 methods such as guaiacol method, lignin method, safrole method, eugenol method, p-cresol method, and electrochemical method. The main production process is the guaiacol-glyoxylic acid method, whose reaction conditions are relatively easy to control, the yield is high, the treatment of three wastes is less, and the post-treatment is convenient. Currently, the world's synthetic vanillin production enterprises, such as Rhodia in France, Borregaard in Norway, and Ube Industries in Japan, all adopt this method. Similarly, large domestic vanillin production enterprises such as Zhejiang Jiaxing Zhonghua Chemical Plant and Jilin Petrochemical Vanillin Plant also adopt this method. This method has become the main production process of synthetic vanillin at home and abroad.

[0004] In the guaiacol-glyoxylic acid method, guaiacol and glyoxylic acid can form 3-methoxy-4-hydroxyphenylmandelic acid under alkaline heating conditions. This acid is oxidized to 3-methoxy-4-hydroxyacetophenone in the presence of a catalyst and oxygen, and then crude vanillin can be obtained through acidification and decarboxylation. This synthesis process requires a large amount of water, the production process is complex and involves the occurrence of various side reactions. The wastewater is high-salt and high-TOC wastewater, the sodium sulfate content reaches 15%, and the organic substances are mainly guaiacol, glyoxylic acid, methyl isobutyl ketone, mandelic acid, and other organic acids. The wastewater treatment is difficult and the treatment cost is high, consuming a large amount of manpower, material resources, and financial resources.

[0005] At present, there are few treatment methods for vanillin wastewater in the industry, mainly including extraction method, adsorption method, and chemical oxidation method. The treatment method of vanillin production wastewater is disclosed in CN112624462A, which is treated by processes such as electrolysis, extraction, concentration, crystallization, and adsorption. However, the process flow is long, the investment is large, and the treatment effect of wastewater COD is limited. Among them, the extraction method is mainly used to remove macromolecular organic substances in wastewater. The equipment used has a large volume and limited extraction capacity. The adsorption method has high use cost and waste disposal cost, and is prone to safety hazards; The treatment method of phenolic wastewater containing phenol in the production process of ethyl vanillin is disclosed in CN113896369A. The organic waste is treated by continuous processes of oxidation, extraction, de-aldehyde, and distillation, and is converted into ethyl vanillin for recovery, which greatly reduces the cost of wastewater treatment and production of ethyl vanillin, and effectively reduces the environmental protection load. However, the treatment efficiency of organic substances in wastewater by its chemical oxidation method is low, the equipment construction and operation costs are high, and finally the wastewater can only be treated by evaporation crystallization. The salt pollutants distilled out are high and difficult to sell externally, and most of them are treated as hazardous waste by outsourcing, resulting in further increased costs.

[0006] Therefore, the treatment of vanillin wastewater is difficult, the treatment process is cumbersome, and the disposal method is single. There is little research on the treatment of this wastewater, and the treatment method needs to be adjusted according to local conditions, which is an urgent problem to be solved in this field. Summary of the Invention

[0007] The purpose of the present invention is to provide a treatment method for vanillin wastewater. Through simple and efficient treatment methods such as stripping, Fenton oxidation, and sodium hypochlorite catalytic oxidation, complex pollutants in the wastewater can be treated. This treatment method for vanillin production wastewater successfully solves the current problems of treatment and disposal of vanillin wastewater, and greatly increases the competitiveness of products.

[0008] In the present invention, the vanillin wastewater refers to the product wastewater obtained by using guaiacol and glyoxylic acid as raw materials, through synthesis, catalytic oxidation, acidification, and decarboxylation. The organic substances include other organic acid substances such as guaiacol, glyoxylic acid, methyl isobutyl ketone, and mandelic acid. The COD content is 3000 - 20000 ppm, and the methyl isobutyl ketone content is 200 - 3000 ppm.

[0009] To achieve the above purpose, the technical solutions adopted in the present invention are as follows:

[0010] S1. Pass steam into the vanillin wastewater for stripping;

[0011] S2. Add ferrous sulfate and hydrogen peroxide to the wastewater after stripping in S1 for Fenton oxidation reaction; After adjusting the pH of the reacted wastewater, add polyaluminum chloride and polyacrylamide for coagulation and flocculation, and obtain Fenton oxidation product water through filtration;

[0012] S3. Feed the effluent from the Fenton oxidation in S2 into the sodium hypochlorite catalytic oxidation reactor, and add sodium hypochlorite for oxidation.

[0013] In the method of the present invention, in the said S1, the steam is water vapor with a working pressure of 0.2 MPaG or 0.4 MPaG. The stripping is controlled such that the bottom temperature of the tower is 70 - 110 °C, the top temperature of the tower is 60 - 100 °C, and the stripping time is 0.5 - 3 h, which can remove the light components in the wastewater, including substances such as small molecule acids and methyl isobutyl ketone.

[0014] In the method of the present invention, in the said S2, the amount of solid ferrous sulfate added is 0.1% - 1% of the mass of the wastewater, the concentration of hydrogen peroxide added is 27.5 - 30 wt%, and the amount added is 0.2% - 1% of the mass of the wastewater.

[0015] The Fenton oxidation temperature is 20 - 90 °C, and the reaction duration is 1 - 4 h.

[0016] The temperature of the wastewater is 20 - 90 °C. First, add ferrous sulfate and mix well, and then add hydrogen peroxide for reaction.

[0017] In the method of the present invention, in the said S2, the pH of the wastewater is adjusted to 7 - 12, and continuous stirring is carried out for 30 - 60 min; the unreacted hydrogen peroxide in the wastewater can be removed.

[0018] The dosage of polyaluminum chloride is 20 - 200 ppm, the dosage of polyacrylamide is 2 - 20 ppm. Based on the COD content of the wastewater, the coagulation and flocculation time is 5 - 30 min, which can precipitate the iron-containing solids (iron sludge) in the heterogeneous wastewater. The wastewater is filtered to obtain clear and transparent effluent from the Fenton oxidation.

[0019] After being treated by S2, the obtained iron sludge is sent out for hazardous waste treatment, and the effluent from the Fenton oxidation is subjected to sodium hypochlorite catalytic oxidation treatment.

[0020] The above reactions can degrade macromolecular substances such as guaiacol, methyl isobutyl ketone, and mandelic acid in the vanillin wastewater into small molecule acids and remove them. At the same time, it has a good removal effect on other pollutants such as metals and phosphorus. After completion, the obtained wastewater is a heterogeneous orange solution, and further treatment is required to obtain the effluent from the Fenton oxidation.

[0021] In the method of the present invention, in the step S3, the catalyst for the catalytic oxidation reaction is the catalyst disclosed in the patent CN106345485B "A Catalyst for Catalytic Oxidation Treatment of Organic Wastewater, Its Preparation Method and Use": including a cerium-modified alumina support and nickel, iron, manganese, and cerium loaded on the cerium-modified alumina support in the form of oxides; the cerium-modified alumina support includes alumina and cerium loaded on the alumina in the form of oxides. Based on the weight of the alumina, the contents of the following components in the catalyst are: nickel 5.0 - 20 wt%, iron 0.5 - 5.5 wt%, manganese 0.5 - 3.5 wt%, cerium 1.5 - 3.0 wt%; and, based on the weight of the alumina, the content of cerium in the cerium-modified alumina support is 1.0 - 2.0 wt%; based on the weight of the alumina, the content of cerium loaded on the cerium-modified alumina support in the catalyst is 0.5 - 2.0 wt%.

[0022] The wastewater is subjected to oxidation treatment in a catalytic oxidation tower, and the space velocity through the catalytic oxidation tower is 1 / 5 BV to 5 BV.

[0023] The use concentration of sodium hypochlorite is 5 - 15 wt%, and the added amount is 2% - 15% of the mass of the wastewater.

[0024] The catalytic oxidation temperature of sodium hypochlorite is 40 - 90 °C, and the space velocity is 1 / 5 - 1 BV.

[0025] The beneficial effects of the present invention are as follows: The method of the present invention is simple, has good organic matter treatment effect, and low wastewater treatment cost; the combination of steam stripping, Fenton oxidation, and sodium hypochlorite catalytic oxidation processes has a strong removal effect on guaiacol, methyl isobutyl ketone, mandelic acid, and other small molecule acids in the wastewater. Their effects on removing volatile substances, macromolecular substances, and small molecule substances in the wastewater complement each other. Through stripping, the formation of small molecule acids that are difficult to remove after the oxidation of MIBK can be avoided, and through Fenton oxidation, macromolecules are degraded into organic matters suitable for removal by the sodium hypochlorite catalytic oxidation process. The above processes are combined in sequence, and the COD removal efficiency can reach 99.7%. Whether the wastewater is treated by evaporation of salt or discharged into the sea (national standard GB31571 - 2015), it can meet the requirements, and it is applicable to the treatment of vanillin wastewater. Specific Embodiments

[0026] The technical solutions of the present invention will be described in detail below in conjunction with specific embodiments. The embodiments described in the present invention only illustrate the present invention, but the protection scope of the present invention is not limited to the following.

[0027] Vanillin wastewater: The vanillin wastewater obtained from Example 1 of the patent "A glyoxylic acid method for producing vanillin CN102010310B" contains methyl isobutyl ketone, guaiacol, mandelic acid and other small molecule substances.

[0028] The catalyst used in the catalytic oxidation with sodium hypochlorite is the catalyst prepared in Example 1 of CN106345485B "A catalyst for catalytic oxidation treatment of organic wastewater, its preparation method and uses".

[0029] Testing method: For COD analysis, ultraviolet spectrophotometry is used; for TOC analysis, a TOC analyzer multiN / C2100S (Analytik Jena AG, Germany) is used; for metal ion analysis, ICP flame atomic absorption spectrometry is used.

[0030]

Example 1

[0031] S1. Take 10 parts of the vanillin wastewater prepared in Example 1 of CN102010310B, with a COD of 8530 ppm and a methyl isobutyl ketone content of 1924 ppm;

[0032] Pass steam at 0.4 MPaG into the wastewater, maintain the column bottom temperature at 90 °C, the column top temperature at 80 °C, and the stripping time at 30 min. The produced water has a COD of 5610 ppm, and the stripped wastewater enters Step S2;

[0033] S2. Cool the stripped produced water in S1 to 60 °C, add ferrous sulfate at 0.37% of the wastewater mass and mix evenly, then add 30 wt% hydrogen peroxide at 0.3% of the wastewater mass, and react for 2 h to remove the organic matter in the wastewater; adjust the pH of the reacted wastewater back to 10 and react for 30 min; then add polyaluminum chloride at an amount of 50 ppm and polyacrylamide at an amount of 10 ppm, and the coagulation and flocculation time is 15 min. After static sedimentation and filtration, the excess metals and organic matter in the water are removed. The clarified produced water has a COD of 2177 ppm, and the produced water enters S3;

[0034] S3. Heat the Fenton oxidation produced water to 80 °C, then add sodium hypochlorite with a concentration of 10 wt% at an amount of 5% of the wastewater mass, and pass it through a sodium hypochlorite catalytic oxidation tower equipped with a catalyst at a space velocity of 1 BV. The produced water has a TOC (about 1 part of COD is equivalent to 3 parts of TOC) of 11 ppm. In this example, the removal efficiency of the COD of the vanillin wastewater reaches 99.7%, meeting the standard in Table 2 of GB31571-2015.

[0035]

Example 2

[0036] S1. Take 10 portions of vanillin wastewater prepared in Example 1 of CN102010310B, with a COD of 8530 ppm and a methyl isobutyl ketone content of 1924 ppm;

[0037] Pass steam at 0.2 MPaG into the wastewater, maintain the bottom temperature of the tower at 70 °C, the top temperature of the tower at 60 °C, and the stripping time at 1 h. The COD of the produced water is 5637 ppm, and the stripped wastewater enters Step S2;

[0038] S2. Cool the temperature of the stripped produced water in S1 to 20 °C, add ferrous sulfate in an amount of 0.2% of the wastewater mass and mix evenly, then add 30 wt% hydrogen peroxide in an amount of 0.7% of the wastewater mass, and react for 4 h to remove the organic matter in the wastewater; adjust the pH of the reacted wastewater back to 12 and react for 30 min; then add polyaluminum chloride in an amount of 20 ppm and polyacrylamide in an amount of 2 ppm, and the coagulation and flocculation time is 15 min. After static precipitation and filtration, remove the excess metals and organic matter in the water. The COD of the obtained clarified produced water is 1784 ppm, and the produced water enters S3; S3. Heat the Fenton oxidation produced water to 40 °C, then add sodium hypochlorite with a concentration of 15 wt% in an amount of 2% of the wastewater mass, and pass it through a sodium hypochlorite catalytic oxidation tower equipped with a catalyst at an airspeed of 1 / 5 BV. The TOC of the obtained produced water (about 3 parts of TOC for 1 part of COD) is 13 ppm. In this example, the removal efficiency of the COD of the vanillin wastewater reaches 99.5%, meeting the standard in Table 2 of GB 31571-2015.

[0039]

Example 3

[0040] S1. Take 10 portions of vanillin wastewater prepared in Example 1 of CN102010310B, with a COD of 8530 ppm and a methyl isobutyl ketone content of 1924 ppm;

[0041] Pass steam at 0.2 MPaG into the wastewater, maintain the bottom temperature of the tower at 110 °C, the top temperature of the tower at 100 °C, and the stripping time at 1.5 h. The COD of the produced water is 5450 ppm, and the stripped wastewater enters Step S2;

[0042] S2. Cool the temperature of the stripped produced water in S1 to 90 °C, add ferrous sulfate in an amount of 0.1% of the wastewater mass and mix evenly, then add 30 wt% hydrogen peroxide in an amount of 0.2% of the wastewater mass, and react for 1 h to remove the organic matter in the wastewater; adjust the pH of the reacted wastewater back to 7 and react for 60 min; then add polyaluminum chloride in an amount of 200 ppm and polyacrylamide in an amount of 20 ppm, and the coagulation and flocculation time is 15 min. After static precipitation and filtration, remove the excess metals and organic matter in the water. The COD of the obtained clarified produced water is 2866 ppm, and the produced water enters S3;

[0043] S3. Cool the effluent from Fenton oxidation to 90 °C, then add sodium hypochlorite with a concentration of 10 wt%, and the addition amount is 15% of the mass of the wastewater. Pass it through the sodium hypochlorite catalytic oxidation tower equipped with a catalyst at a space velocity of 1 BV. The TOC of the obtained effluent (about 3 parts of TOC for 1 part of COD) is 12 ppm. In this example, the removal efficiency of COD in vanillin wastewater reaches 99.6%, meeting the standard in Table 2 of the national standard GB31571-2015.

[0044]

Example 4

[0045] S1. Take 10 parts of vanillin wastewater prepared in Example 1 of CN102010310B, with a COD of 8530 ppm and a methyl isobutyl ketone content of 1924 ppm;

[0046] Pass steam at 0.4 MPaG into the wastewater, maintain the tower bottom temperature at 90 °C, the tower top temperature at 80 °C, and the stripping time at 3 h. The COD of the effluent is 5610 ppm. The wastewater after stripping enters step S2;

[0047] S2. Cool the temperature of the stripped effluent in S1 to 60 °C, add ferrous sulfate in an amount of 0.1% of the mass of the wastewater and mix evenly, then add 30 wt% hydrogen peroxide in an amount of 1% of the mass of the wastewater, and react for 2 h to remove the organic matter in the wastewater; adjust the pH of the reacted wastewater back to 10 and react for 30 min; then add polyaluminum chloride in an amount of 100 ppm and polyacrylamide in an amount of 10 ppm, and the coagulation and flocculation time is 15 min. After static precipitation and filtration, remove the excess metals and organic matter in the water. The COD of the obtained clarified effluent is 2021 ppm, and the effluent enters S3;

[0048] S3. Heat the effluent from Fenton oxidation to 60 °C, then add sodium hypochlorite with a concentration of 10 wt%, and the addition amount is 10% of the mass of the wastewater. Pass it through the sodium hypochlorite catalytic oxidation tower equipped with a catalyst at a space velocity of 1 / 2 BV. The TOC of the obtained effluent (about 3 parts of TOC for 1 part of COD) is 13 ppm. In this example, the removal efficiency of COD in vanillin wastewater reaches 99.5%, meeting the standard in Table 2 of the national standard GB31571-2015.

[0049]

Example 5

[0050] S1. Take 10 parts of vanillin wastewater prepared in Example 1 of CN102010310B, with a COD of 8530 ppm and a methyl isobutyl ketone content of 1924 ppm;

[0051] Pass steam at 0.2 MPaG into the wastewater, maintain the tower bottom temperature at 80 °C, the tower top temperature at 70 °C, and the stripping time at 30 min. The COD of the effluent is 5514 ppm. The wastewater after stripping enters step S2;

[0052] S2. Lower the temperature of the stripped produced water in S1 to 40 °C, add ferrous sulfate in an amount of 0.4% of the wastewater mass and mix evenly, then add 30 wt% hydrogen peroxide in an amount of 0.2% of the wastewater mass, react for 3 h to remove the organic matter in the wastewater; adjust the pH of the reacted wastewater back to 10 and react for 30 min; then add polyaluminum chloride in an amount of 50 ppm and polyacrylamide in an amount of 10 ppm, and the coagulation and flocculation time is 15 min. After static precipitation and filtration, remove the excess metals and organic matter in the water. The clarified produced water has a COD of 1216 ppm, and the produced water enters S3;

[0053] S3. Heat the Fenton oxidation produced water to 50 °C, then add sodium hypochlorite with a concentration of 15 wt%, and the addition amount is 5% of the wastewater mass. Pass it through the sodium hypochlorite catalytic oxidation tower equipped with a catalyst at a space velocity of 1 BV. The produced water has a TOC (about 3 parts of TOC for 1 part of COD) of 11 ppm. In this example, the removal efficiency of the COD of the vanillin wastewater reaches 99.6%, meeting the standard in Table 2 of the national standard GB31571-2015.

[0054]

Comparative Example 1

[0055] S1. Take 10 parts of the vanillin wastewater prepared in Example 1 of CN102010310B, with a COD of 8530 ppm and a methyl isobutyl ketone content of 1924 ppm, and enter step S2;

[0056] S2. Raise the temperature of the wastewater in S1 to 60 °C, add ferrous sulfate in an amount of 0.5% of the wastewater mass and mix evenly, then add 30 wt% hydrogen peroxide in an amount of 0.5% of the wastewater mass, react for 2 h to remove the organic matter in the wastewater; adjust the pH of the reacted wastewater back to 10 and react for 30 min; then add polyaluminum chloride in an amount of 50 ppm and polyacrylamide in an amount of 10 ppm, and the coagulation and flocculation time is 15 min. After static precipitation and filtration, remove the excess metals and organic matter in the water. The clarified produced water has a COD of 4375 ppm, and the produced water enters S3;

[0057] S3. Heat the Fenton oxidation produced water to 80 °C, then add sodium hypochlorite with a concentration of 15 wt%, and the addition amount is 5.5% of the wastewater mass. Pass it through the sodium hypochlorite catalytic oxidation tower equipped with a catalyst at a space velocity of 1 BV. The produced water has a TOC (about 3 parts of TOC for 1 part of COD) of 552 ppm. In this example, the removal efficiency of the COD of the vanillin wastewater reaches 80.6%, which does not meet the standard in Table 2 of the national standard GB31571-2015, and the effect is worse than that of the example.

[0058]

Comparative Example 2

[0059] S1. Take 10 portions of vanillin wastewater prepared in Example 1 of CN102010310B, with a COD of 8530 ppm and a methyl isobutyl ketone content of 1924 ppm;

[0060] Pass steam at 0.4 MPaG into the wastewater, maintain the bottom temperature of the tower at 90 °C, the top temperature at 80 °C, and the stripping time at 30 min. The produced water has a COD of 5610 ppm, and the stripped wastewater enters Step S2;

[0061] S2. Heat the stripped produced water to 80 °C, then add sodium hypochlorite with a concentration of 10 wt%, and the addition amount is 5% of the wastewater mass. Pass it through a sodium hypochlorite catalytic oxidation tower equipped with a catalyst at a space velocity of 1 BV. The produced water has a TOC (about 1 part of COD is equivalent to 3 parts of TOC) of 1504 ppm. In this example, the removal efficiency of the COD of vanillin wastewater reaches 47.1%, which does not meet the standard in Table 2 of GB 31571-2015, and the effect is worse than that of the example.

[0062]

Comparative Example 3

[0063] S1. Take 10 portions of vanillin wastewater prepared in Example 1 of CN102010310B, with a COD of 8530 ppm and a methyl isobutyl ketone content of 1924 ppm;

[0064] Pass steam at 0.4 MPaG into the wastewater, maintain the bottom temperature of the tower at 90 °C, the top temperature at 80 °C, and the stripping time at 30 min. The produced water has a COD of 5610 ppm, and the stripped wastewater enters Step S2;

[0065] S2. Cool the stripped produced water in S1 to 60 °C, add ferrous sulfate in an amount of 0.5% of the wastewater mass and mix evenly, then add 30 wt% hydrogen peroxide in an amount of 0.5% of the wastewater mass, and react for 2 h to remove the organic matter in the wastewater; adjust the pH of the reacted wastewater back to 10 and react for 30 min; then add polyaluminum chloride in an amount of 50 ppm and polyacrylamide in an amount of 10 ppm, and the coagulation and flocculation time is 15 min. After static precipitation and filtration, the excess metals and organic matter in the water are removed. The clarified produced water has a COD of 2758 ppm. In this comparative example, the removal efficiency of the COD of vanillin wastewater is 67.7%, which does not meet the standard in Table 2 of GB31571-2015, and the effect is worse than that of the example.

[0066]

Comparative Example 4

[0067] S1. Take 10 portions of vanillin wastewater prepared in Example 1 of CN102010310B, with a COD of 8530 ppm and a methyl isobutyl ketone content of 1924 ppm;

[0068] S2. Heat the wastewater to 80 °C, then add sodium hypochlorite with a concentration of 10 wt%, and the addition amount is 5% of the wastewater mass. Install a sodium hypochlorite catalytic oxidation tower with a catalyst at a space velocity of 1 BV. The produced water has a COD of 6478 ppm, and the produced water enters S3;

[0069] S3. Pass steam at 0.4 MPaG into the produced water from sodium hypochlorite catalytic oxidation, keep the bottom temperature of the tower at 90 °C, the top temperature at 80 °C, and the stripping time at 30 min. The produced water has a COD of 6236 ppm. The wastewater after stripping enters Step S4;

[0070] S4. Cool the temperature of the stripped produced water in S3 to 60 °C, add ferrous sulfate in an amount of 0.37% of the wastewater mass and mix evenly, then add hydrogen peroxide with a concentration of 30 wt% in an amount of 0.3% of the wastewater mass, and react for 2 h to remove the organic matter in the wastewater; adjust the pH of the reacted wastewater back to 10 and react for 30 min; then add polyaluminum chloride in an amount of 50 ppm and polyacrylamide in an amount of 10 ppm, and the coagulation and flocculation time is 15 min. After static precipitation and filtration, the excess metals and organic matter in the water are removed, and the clarified produced water has a COD of 2298 ppm. The removal efficiency of the COD of the vanillin wastewater in this example reaches 73.1%, which does not meet the standard in Table 2 of GB31571-2015, and the effect is worse than that of the example.

[0071] The above is only the preferred implementation mode of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, should not be regarded as excluding other embodiments, but can be used in various materials, environments and combination forms, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge in related fields. And the modifications and supplements made by those skilled in the art do not depart from the main idea and content of the present invention, and these improvements and supplements should also be regarded as the protection scope of the present invention.

Claims

1. A method for treating vanillin wastewater, characterized in that, It includes the following steps: S1. Pass steam into the vanillin wastewater for stripping; S2. Add ferrous sulfate and hydrogen peroxide to the wastewater after stripping in S1 for oxidation reaction; after the reaction, adjust the pH of the wastewater and then add polyaluminum chloride and polyacrylamide for coagulation and flocculation, and obtain the Fenton oxidation effluent through filtration; S3. Pass the Fenton oxidation effluent in S2 into a sodium hypochlorite catalytic oxidation reactor and add sodium hypochlorite for oxidation.

2. The treatment method according to claim 1, characterized in that: In the above S1, the steam is water vapor with a working pressure of 0.2MPaG or 0.4MPaG, and the stripping time is 30 - 180min.

3. The treatment method according to claim 1 or 2, characterized in that: The stripping is carried out using a stripping column. The temperature of the stripping column bottom is controlled at 70 - 110°C, and the temperature of the stripping column top is controlled at 60 - 100°C.

4. The treatment method according to any one of claims 1 - 3, characterized in that: In the above S2, the addition amount of ferrous sulfate is 0.1% - 1.0% of the wastewater mass.

5. The treatment method according to any one of claims 1 - 4, characterized in that: In the above S2, the concentration of hydrogen peroxide is 27.5 - 30wt%, the addition amount is 0.2% - 1% of the wastewater mass, and / or the reaction temperature is 20 - 90°C, and the reaction duration is 1 - 4h.

6. The treatment method according to any one of claims 1 - 5, characterized in that: In the above S2, the wastewater temperature is 20 - 90°C. First, add ferrous sulfate and mix evenly, and then add hydrogen peroxide for reaction.

7. The treatment method according to any one of claims 1 - 6, characterized in that: In the above S2, the pH of the wastewater is adjusted to 7 - 12 and stirred continuously for 30 - 60min; and / or the addition amount of polyaluminum chloride is 20 - 200ppm based on the wastewater COD content, and / or the addition amount of polyacrylamide is 2 - 20ppm based on the wastewater COD content, and / or the coagulation and flocculation time is 5 - 30min.

8. The treatment method according to any one of claims 1 - 7, characterized in that: In the above S3, the usage concentration of sodium hypochlorite is 5 - 15wt%, and the addition amount is 2% - 15% of the wastewater mass.

9. The treatment method according to any one of claims 1 - 8, characterized in that: In the above S3, the sodium hypochlorite catalytic oxidation temperature is 40 - 90°C, and the space velocity is 1 / 5 - 1BV.

10. The treatment method according to any one of claims 1 - 9, characterized in that, In the above S3, the catalyst for the catalytic oxidation reaction includes a cerium-modified alumina support and nickel, iron, manganese, and cerium loaded on the cerium-modified alumina support in the form of oxides; the cerium-modified alumina support includes alumina and cerium loaded on the alumina in the form of oxides. Based on the weight of the alumina, the content of the following components in the catalyst is: nickel 5.0 - 20wt%, iron 0.5 - 5.5wt%, manganese 0.5 - 3.5wt%, cerium 1.5 - 3.0wt%; and, based on the weight of the alumina, the content of cerium in the cerium-modified alumina support is 1.0 - 2.0wt%; based on the weight of the alumina, the content of cerium loaded on the cerium-modified alumina support in the catalyst is 0.5 - 2.0wt%.