Advanced treatment process of sulfate pulping wastewater

Abstract

The invention discloses an advanced treatment process of sulfate pulping wastewater, which comprises the following steps: (1) first-grid treatment: adding a treating agent A into pretreated sulfate pulping wastewater, stirring, standing, precipitating and filtering to obtain first filtrate; the treating agent is prepared from the following components: p-toluenesulfonic acid, sodium dodecyl benzene sulfonate, tannic acid, 1, 3, 5-benzene triboric acid, a graphene oxide aqueous solution and 1, 4-dioxane; (2) second-grid treatment: adding polymeric ferric sulfate and a treating agent B, stirring, standing for precipitation, and filtering to obtain a second filtrate; the treatment agent B is prepared from the following components: acetic acid, chitosan, polyethyleneimine, N6-methyladenosine, sodium hydroxide, hydroxylamine hydrochloride, ketorolac tromethamine and water; and (3) third-grid treatment: adding cationic polyacrylamide, stirring, adjusting the pH value, precipitating and filtering to obtain discharged water. The treatment process is simple, pollutants in the wastewater can be efficiently removed, and the emission standard is met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pulp wastewater treatment, in particular to a deep treatment process of kraft pulp wastewater. BACKGROUND

[0002] The pulp wastewater is also the waste liquid in the cooking section, including the black liquor of alkali pulping and the red liquor of acid pulping. The waste liquid has high concentration and contains a large amount of pollutants. First, in the process of pulp preparation, wood or other fiber raw materials are treated by chemical or mechanical methods, releasing a large amount of organic substances such as lignin, cellulose and their degradation products, which are not only difficult to degrade but also have certain toxicity, causing potential threats to the aquatic ecosystem. Especially in the process of sulfuric acid pulping, the produced sulfate and its reducing substances such as hydrogen sulfide have serious harm to aquatic organisms. Secondly, the pulp wastewater is also accompanied by a large amount of suspended solids and chemical oxygen demand (COD). The suspended solids mainly include undissolved fibers, wood chips, dust and other solid particles, and their concentration directly reflects the turbidity and pollution degree of the wastewater. COD is an index to measure the oxidation of organic matter, and high COD value not only reflects the concentration of organic matter in the water, but also implies that the biological oxygen demand and chemical oxygen demand in the wastewater are high, thus intensifying the eutrophication of water body and the load of ecological system. Finally, the pulp wastewater often contains some substances with toxicity and biological accumulation, such as heavy metals and organic chlorine compounds, which often come from pollutants in raw materials or additives in the production process. Their discharge will pose a long-term potential risk to aquatic organisms, water ecosystem and human health, which needs to be restricted and treated by strict monitoring and control means. The treatment of this section wastewater has always been considered a technical problem. Since the research and application of deep treatment technology for pulp wastewater are relatively short, it is urgent to develop an efficient and green treatment method for pulp wastewater. SUMMARY

[0003] In view of the above defects of the prior art, the present application provides a deep treatment process of kraft pulp wastewater to solve the problems in the background art.

[0004] To achieve the above purpose, the present application provides the following technical scheme: A deep treatment process of kraft pulp wastewater, comprising the following steps: (1) First tank treatment: adding a treatment agent A to the pretreated kraft pulp wastewater, stirring, standing and precipitating, filtering to obtain a first filtrate; The treatment agent A comprises the following components by weight fraction: 10-20 parts of p-toluenesulfonic acid, 10-15 parts of sodium dodecyl benzene sulfonate, 5-10 parts of tannic acid, 2-6 parts of 1,3,5-benzene trisulfonic acid, 1-5 parts of graphene oxide aqueous solution and 100-200 parts of 1,4-dioxane; (2) Second treatment: Adjust the pH of the first filtrate obtained in step (1) to 3.3~3.8, add polyferric sulfate and treatment agent B, and aerate at 1.0-1.2 m. 3 / (m 2 ·h) Stir while allowing the mixture to stand and settle, then filter to obtain the second filtrate; The treatment agent B, by weight, comprises the following components: 10-20 parts acetic acid, 0.5-1.0 parts chitosan, 10-20 parts polyethyleneimine, 0.3-0.8 parts N6-methyladenosine, 1-5 parts sodium hydroxide, 1-5 parts hydroxylamine hydrochloride, 10-30 parts ketorolac tromethamine, and 80-150 parts water; (3) Third treatment: Add cationic polyacrylamide to the second filtrate obtained in step (2), stir, adjust the pH, let it stand to precipitate, filter, and obtain the discharged water.

[0005] Preferably, the pretreated sulfate pulping wastewater in step (1) is obtained by sequentially passing it through a bar screen, a sieve filter, and gravity sedimentation. First, a parallel bar (1000mm wide, 6mm spacing) is used to intercept large floating particles. Then, it is filtered through a reverse-cutting rotating fine bar with a diameter of 1.0m and a mesh size of 60. Finally, the filtrate flows into a horizontal flow sedimentation tank for gravity sedimentation, and the effluent from the sedimentation tank is the pretreated sulfate pulping wastewater.

[0006] Preferably, the amount of treatment agent A added is 50~100 mg / L.

[0007] Preferably, the preparation method of the treatment agent A in step (1) includes the following steps: S1. Sodium dodecylbenzenesulfonate, p-toluenesulfonic acid and 1,4-dioxane are mixed to obtain a mixture; S2. First, add the aqueous solution of graphene oxide to the mixture and stir. Then, add tannic acid and 1,3,5-benzenetriboronic acid and react in a sealed environment at 80~120℃ to obtain a solid product. S3. Immerse the solid in anhydrous ethanol, wash with acetone, repeat 3-5 times, and vacuum dry to obtain treatment agent A.

[0008] Preferably, the concentration of the graphene oxide aqueous solution is 5~10 mg / mL.

[0009] Preferably, the stirring time in step S2 is 25-40 min, and the sealed reaction time is 100-200 min.

[0010] Preferably, the amount of polyferric sulfate added is 35~60 mg / L, and the amount of treatment agent B added is 100~300 mg / L.

[0011] Preferably, the preparation method of the treatment agent B in step (2) includes the following steps: (a) Mix acetic acid, chitosan, N6-methyladenosine and sodium hydroxide, stir and then add polyethyleneimine. React at 50-60°C for 5-10 h. Wash the obtained solid product 2-3 times and dry it to obtain the modified product. (b) Mix hydroxylamine hydrochloride, ketorolac tromethamine and water, and stir for 15-25 minutes to form a soaking solution; (c) Add the modified material to the soaking solution and soak at 70~75℃ for 10~15h, wash and dry to obtain treatment agent B.

[0012] Preferably, the solvent used for washing is 1,4-dioxane.

[0013] Preferably, the amount of cationic polyacrylamide added is 3~10 ppm.

[0014] Preferably, step (3) involves adjusting the pH to 7.0-8.5.

[0015] Preferably, the stirring speed mentioned above is 100~300 r / min.

[0016] Compared with the prior art, the beneficial effects of the present invention are: Pretreated sulfate pulping wastewater was sequentially treated in three treatment tanks, with particular emphasis on treatment agents A and B to improve effluent quality. In treatment agent A, tannic acid containing phenolic hydroxyl groups can cross-link and adsorb lignin, reducing the content and color value of dissolved organic pollutants in the wastewater. 1,3,5-Benzenetriboric acid, containing boric acid groups, can match chlorine atoms in adsorbable organic halogens, forming covalent complexes with their hydroxyl groups, achieving targeted capture of adsorbable organic halogens. The layered structure of graphene oxide provides a high specific surface area for electrostatic adsorption, further trapping these pollutants. In treatment agent B, chitosan, modified by the other components, strengthens the bonding between functional groups, enhancing its adsorption and flocculation properties. Polyethyleneimine, along with other active ingredients, synergistically exerts an electrostatic neutralization effect, improving the capture efficiency of negatively charged pollutants. Detailed Implementation

[0017] To enable those skilled in the art to better understand the technical content of the present invention, the technical solution of the present invention will be further described in detail below with reference to specific embodiments.

[0018] Example 1 A process for advanced treatment of sulfate pulping wastewater includes the following steps: (1) First treatment: Add 50 mg / L of treatment agent A to the pretreated sulfate pulping wastewater, stir at 150 r / min, let stand for 60 min to settle, filter, and obtain the first filtrate; the pretreated sulfate pulping wastewater is obtained by passing through grid screening, screen filtration and gravity sedimentation treatment in sequence. The treatment agent A comprises the following components by weight: 10 parts p-toluenesulfonic acid, 10 parts sodium dodecylbenzenesulfonate, 5 parts tannic acid, 2 parts 1,3,5-benzenetriboronic acid, 1 part graphene oxide aqueous solution, and 100 parts 1,4-dioxane. The preparation method of the treatment agent A includes the following steps: S1. Sodium dodecylbenzenesulfonate, p-toluenesulfonic acid and 1,4-dioxane are mixed and ultrasonically dispersed to obtain a mixture; S2. First, add the aqueous solution of graphene oxide to the mixture and stir for 25 minutes. Then, add tannic acid and 1,3,5-benzenetriboronic acid and react in a sealed environment at 80°C for 100 minutes to obtain a solid. S3. Immerse the solid in anhydrous ethanol, wash with acetone, repeat 3 times, and dry under vacuum to obtain treatment agent A. (2) Second treatment: Adjust the pH of the first filtrate obtained in step (1) to 3.3, add 35 mg / L polyferric sulfate and 100 mg / L treatment agent B, aerate and stir, let stand for 40 min to precipitate, filter to obtain the second filtrate; The treatment agent B, by weight, comprises the following components: 10 parts acetic acid, 0.5 parts chitosan, 10 parts polyethyleneimine, 0.3 parts N6-methyladenosine, 1 part sodium hydroxide, 1 part hydroxylamine hydrochloride, 10 parts ketorolac tromethamine, and 80 parts water. The preparation method of treatment agent B includes the following steps: (a) Mix acetic acid, chitosan, N6-methyladenosine and sodium hydroxide, stir and then add polyethyleneimine. React at 50°C for 5 hours. Wash the obtained solid product twice and dry it to obtain the modified product. (b) Mix hydroxylamine hydrochloride, ketorolac tromethamine and water, and stir for 15 minutes to form a soaking solution; (c) Add the modified material to the soaking solution, soak at 70°C for 10 hours, wash with 1,4-dioxane and dry to obtain treatment agent B; (3) Third treatment: Add 3 ppm cationic polyacrylamide to the second filtrate obtained in step (2), stir, adjust the pH to 7.0, let it stand to precipitate, filter, and obtain the discharged water.

[0019] Example 2 A process for advanced treatment of sulfate pulping wastewater includes the following steps: (1) First treatment: Add 100 mg / L of treatment agent A to the pretreated sulfate pulping wastewater, stir at 2000 r / min, let stand for 60 min to settle, filter, and obtain the first filtrate; the pretreated sulfate pulping wastewater is obtained by passing through grid screening, screen filtration and gravity sedimentation treatment in sequence; The treatment agent A, by weight, comprises the following components: 20 parts p-toluenesulfonic acid, 15 parts sodium dodecylbenzenesulfonate, 10 parts tannic acid, 6 parts 1,3,5-benzenetriboronic acid, 5 parts graphene oxide aqueous solution, and 200 parts 1,4-dioxane. The preparation method of the treatment agent A includes the following steps: S1. Sodium dodecylbenzenesulfonate, p-toluenesulfonic acid and 1,4-dioxane are mixed and ultrasonically dispersed to obtain a mixture; S2. First, add the aqueous solution of graphene oxide to the mixture and stir for 40 min. Then, add tannic acid and 1,3,5-benzenetriboronic acid and react in a sealed environment at 120°C for 200 min to obtain a solid. S3. Immerse the solid in anhydrous ethanol, wash with acetone, repeat 5 times, and vacuum dry to obtain treatment agent A. (2) Second treatment: Adjust the pH of the first filtrate obtained in step (1) to 3.8, add 60 mg / L polyferric sulfate and 300 mg / L treatment agent B, aerate and stir, let stand for 40 min to precipitate, filter, and obtain the second filtrate; The treatment agent B, by weight, comprises the following components: 20 parts acetic acid, 1.0 part chitosan, 20 parts polyethyleneimine, 0.8 parts N6-methyladenosine, 5 parts sodium hydroxide, 5 parts hydroxylamine hydrochloride, 30 parts ketorolac tromethamine, and 150 parts water. The preparation method of the treatment agent B includes the following steps: (a) Mix acetic acid, chitosan, N6-methyladenosine and sodium hydroxide, stir and then add polyethyleneimine. React at 60°C for 10 h. Wash the obtained solid product three times and dry it to obtain the modified product. (b) Mix hydroxylamine hydrochloride, ketorolac tromethamine and water, and stir for 25 minutes to form an soaking solution; (c) Add the modified material to the soaking solution, soak at 75°C for 15 hours, wash with 1,4-dioxane and dry to obtain treatment agent B; (3) Third treatment: Add 10 ppm cationic polyacrylamide to the second filtrate obtained in step (2), stir, adjust the pH to 8.5, let it stand to precipitate, filter, and obtain the discharged water.

[0020] Example 3 A process for advanced treatment of sulfate pulping wastewater includes the following steps: (1) First treatment: Add 80 mg / L of treatment agent A to the pretreated sulfate pulping wastewater, stir at 300 r / min, let it stand for 60 min to settle, filter, and obtain the first filtrate; the pretreated sulfate pulping wastewater is obtained by passing through grid screening, screen filtration and gravity sedimentation treatment in sequence. The treatment agent A, by weight, comprises the following components: 15 parts p-toluenesulfonic acid, 12 parts sodium dodecylbenzenesulfonate, 8 parts tannic acid, 4 parts 1,3,5-benzenetriboronic acid, 2 parts graphene oxide aqueous solution, and 150 parts 1,4-dioxane. The preparation method of the treatment agent A includes the following steps: S1. Sodium dodecylbenzenesulfonate, p-toluenesulfonic acid and 1,4-dioxane are mixed and ultrasonically dispersed to obtain a mixture; S2. First, add the aqueous solution of graphene oxide to the mixture and stir for 30 min. Then, add tannic acid and 1,3,5-benzenetriboronic acid and react in a sealed environment at 100°C for 150 min to obtain a solid product. S3. Immerse the solid in anhydrous ethanol, wash with acetone, repeat 4 times, and vacuum dry to obtain treatment agent A. (2) Second treatment: Adjust the pH of the first filtrate obtained in step (1) to 3.6, add 40 mg / L polyferric sulfate and 200 mg / L treatment agent B, aerate and stir, let stand for 40 min to precipitate, filter to obtain the second filtrate; The treatment agent B, by weight, comprises the following components: 15 parts acetic acid, 0.8 parts chitosan, 15 parts polyethyleneimine, 0.5 parts N6-methyladenosine, 2 parts sodium hydroxide, 2 parts hydroxylamine hydrochloride, 20 parts ketorolac tromethamine, and 100 parts water. The preparation method of the treatment agent B includes the following steps: (a) Mix acetic acid, chitosan, N6-methyladenosine and sodium hydroxide, stir and then add polyethyleneimine. React at 55°C for 8 hours. Wash the obtained solid product three times and dry it to obtain the modified product. (b) Mix hydroxylamine hydrochloride, ketorolac tromethamine and water, and stir for 20 minutes to form an soaking solution; (c) Add the modified material to the soaking solution, soak at 72°C for 12 hours, wash with 1,4-dioxane and dry to obtain treatment agent B; (3) Third treatment: Add 6 ppm cationic polyacrylamide to the second filtrate obtained in step (2), stir, adjust the pH to 8.0, let it stand to precipitate, filter, and obtain the effluent.

[0021] Comparative Example 1 The difference between this comparative example and Example 3 is that sodium dodecylbenzenesulfonate in component A of the treatment agent is replaced with 2,5-diaminobenzenesulfonic acid, while the other components and steps remain unchanged.

[0022] A process for advanced treatment of sulfate pulping wastewater includes the following steps: (1) First treatment: Add 80 mg / L of treatment agent A to the pretreated sulfate pulping wastewater, stir at 300 r / min, let it stand for 60 min to settle, filter, and obtain the first filtrate; the pretreated sulfate pulping wastewater is obtained by passing through grid screening, screen filtration and gravity sedimentation treatment in sequence. The treatment agent A, by weight, comprises the following components: 15 parts p-toluenesulfonic acid, 12 parts 2,5-diaminobenzenesulfonic acid, 8 parts tannic acid, 4 parts 1,3,5-benzenetriboronic acid, 2 parts graphene oxide aqueous solution, and 150 parts 1,4-dioxane. The preparation method of the treatment agent A includes the following steps: S1. Mix 2,5-diaminobenzenesulfonic acid, p-toluenesulfonic acid and 1,4-dioxane, and disperse by ultrasonication to obtain a mixed solution; S2. First, add the aqueous solution of graphene oxide to the mixture and stir for 30 min. Then, add tannic acid and 1,3,5-benzenetriboronic acid and react in a sealed environment at 100°C for 150 min to obtain a solid product. S3. Immerse the solid in anhydrous ethanol, wash with acetone, repeat 4 times, and vacuum dry to obtain treatment agent A. (2) Second treatment: Adjust the pH of the first filtrate obtained in step (1) to 3.6, add 40 mg / L polyferric sulfate and 200 mg / L treatment agent B, aerate and stir, let stand for 40 min to precipitate, filter to obtain the second filtrate; The treatment agent B, by weight, comprises the following components: 15 parts acetic acid, 0.8 parts chitosan, 15 parts polyethyleneimine, 0.5 parts N6-methyladenosine, 2 parts sodium hydroxide, 2 parts hydroxylamine hydrochloride, 20 parts ketorolac tromethamine, and 100 parts water. The preparation method of the treatment agent B includes the following steps: (a) Mix acetic acid, chitosan, N6-methyladenosine and sodium hydroxide, stir and then add polyethyleneimine. React at 55°C for 8 hours. Wash the obtained solid product three times and dry it to obtain the modified product. (b) Mix hydroxylamine hydrochloride, ketorolac tromethamine and water, and stir for 20 minutes to form an soaking solution; (c) Add the modified material to the soaking solution, soak at 72°C for 12 hours, wash with 1,4-dioxane and dry to obtain treatment agent B; (3) Third treatment: Add 6 ppm cationic polyacrylamide to the second filtrate obtained in step (2), stir, adjust the pH to 8.0, let it stand to precipitate, filter, and obtain the effluent.

[0023] Comparative Example 2 The difference between this comparative example and Example 3 is that no treatment agent A was added during the first treatment, while the other components and steps remained the same.

[0024] A process for advanced treatment of sulfate pulping wastewater includes the following steps: (1) First treatment: The pretreated sulfate pulping wastewater was allowed to stand for 60 minutes to settle, then filtered to obtain the first filtrate; the pretreated sulfate pulping wastewater was obtained by passing through a grid screen, a screen filter and gravity sedimentation treatment in sequence. (2) Second treatment: Adjust the pH of the first filtrate obtained in step (1) to 3.6, add 40 mg / L polyferric sulfate and 200 mg / L treatment agent B, aerate and stir, let stand for 40 min to precipitate, filter to obtain the second filtrate; The treatment agent B, by weight, comprises the following components: 15 parts acetic acid, 0.8 parts chitosan, 15 parts polyethyleneimine, 0.5 parts N6-methyladenosine, 2 parts sodium hydroxide, 2 parts hydroxylamine hydrochloride, 20 parts ketorolac tromethamine, and 100 parts water. The preparation method of the treatment agent B includes the following steps: (a) Mix acetic acid, chitosan, N6-methyladenosine and sodium hydroxide, stir and then add polyethyleneimine. React at 55°C for 8 hours. Wash the obtained solid product three times and dry it to obtain the modified product. (b) Mix hydroxylamine hydrochloride, ketorolac tromethamine and water, and stir for 20 minutes to form an soaking solution; (c) Add the modified material to the soaking solution, soak at 72°C for 12 hours, wash with 1,4-dioxane and dry to obtain treatment agent B; (3) Third treatment: Add 6 ppm cationic polyacrylamide to the second filtrate obtained in step (2), stir, adjust the pH to 8.0, let it stand to precipitate, filter, and obtain the effluent.

[0025] Comparative Example 3 The difference between this comparative example and Example 3 is that the chitosan in component B of the treatment agent is replaced with sodium alginate, while the other components and steps remain unchanged.

[0026] A process for advanced treatment of sulfate pulping wastewater includes the following steps: (1) First treatment: Add 80 mg / L of treatment agent A to the pretreated sulfate pulping wastewater, stir at 300 r / min, let it stand for 60 min to settle, filter, and obtain the first filtrate; the pretreated sulfate pulping wastewater is obtained by passing through grid screening, screen filtration and gravity sedimentation treatment in sequence. The treatment agent A, by weight, comprises the following components: 15 parts p-toluenesulfonic acid, 12 parts sodium dodecylbenzenesulfonate, 8 parts tannic acid, 4 parts 1,3,5-benzenetriboronic acid, 2 parts graphene oxide aqueous solution, and 150 parts 1,4-dioxane. The preparation method of the treatment agent A includes the following steps: S1. Sodium dodecylbenzenesulfonate, p-toluenesulfonic acid and 1,4-dioxane are mixed and ultrasonically dispersed to obtain a mixture; S2. First, add the aqueous solution of graphene oxide to the mixture and stir for 30 min. Then, add tannic acid and 1,3,5-benzenetriboronic acid and react in a sealed environment at 100°C for 150 min to obtain a solid product. S3. Immerse the solid in anhydrous ethanol, wash with acetone, repeat 4 times, and vacuum dry to obtain treatment agent A. (2) Second treatment: Adjust the pH of the first filtrate obtained in step (1) to 3.6, add 40 mg / L polyferric sulfate and 200 mg / L treatment agent B, aerate and stir, let stand for 40 min to precipitate, filter to obtain the second filtrate; The treatment agent B, by weight, comprises the following components: 15 parts acetic acid, 0.8 parts sodium alginate, 15 parts polyethyleneimine, 0.5 parts N6-methyladenosine, 2 parts sodium hydroxide, 2 parts hydroxylamine hydrochloride, 20 parts ketorolac tromethamine, and 100 parts water. The preparation method of the treatment agent B includes the following steps: (a) Mix acetic acid, sodium alginate, N6-methyladenosine and sodium hydroxide, stir and then add polyethyleneimine. React at 55°C for 8 hours. Wash the obtained solid product three times and dry it to obtain the modified product. (b) Mix hydroxylamine hydrochloride, ketorolac tromethamine and water, and stir for 20 minutes to form an soaking solution; (c) Add the modified material to the soaking solution, soak at 72°C for 12 hours, wash with 1,4-dioxane and dry to obtain treatment agent B; (3) Third treatment: Add 6 ppm cationic polyacrylamide to the second filtrate obtained in step (2), stir, adjust the pH to 8.0, let it stand to precipitate, filter, and obtain the effluent.

[0027] Comparative Example 4 The difference between this comparative example and Example 3 is that no treatment agent B was added in the second treatment of the deep processing process, while the other components and steps remain unchanged.

[0028] A process for advanced treatment of sulfate pulping wastewater includes the following steps: (1) First treatment: Add 80 mg / L of treatment agent A to the pretreated sulfate pulping wastewater, stir at 300 r / min, let it stand for 60 min to settle, filter, and obtain the first filtrate; the pretreated sulfate pulping wastewater is obtained by passing through grid screening, screen filtration and gravity sedimentation treatment in sequence. The treatment agent A, by weight, comprises the following components: 15 parts p-toluenesulfonic acid, 12 parts sodium dodecylbenzenesulfonate, 8 parts tannic acid, 4 parts 1,3,5-benzenetriboronic acid, 2 parts graphene oxide aqueous solution, and 150 parts 1,4-dioxane. The preparation method of the treatment agent A includes the following steps: S1. Sodium dodecylbenzenesulfonate, p-toluenesulfonic acid and 1,4-dioxane are mixed and ultrasonically dispersed to obtain a mixture; S2. First, add the aqueous solution of graphene oxide to the mixture and stir for 30 min. Then, add tannic acid and 1,3,5-benzenetriboronic acid and react in a sealed environment at 100°C for 150 min to obtain a solid product. S3. Immerse the solid in anhydrous ethanol, wash with acetone, repeat 4 times, and vacuum dry to obtain treatment agent A. (2) Second treatment: Adjust the pH of the first filtrate obtained in step (1) to 3.6, add 240 mg / L polyferric sulfate, aerate and stir, let stand for 40 min to precipitate, filter, and obtain the second filtrate; (3) Third treatment: Add 10 ppm cationic polyacrylamide to the second filtrate obtained in step (2), stir, adjust the pH to 8.0, let it stand to precipitate, filter, and obtain the discharged water.

[0029] Comparative Example 5 A process for advanced treatment of sulfate pulping wastewater includes the following steps: (1) First treatment: Add 40 mg / L polyferric sulfate to the pretreated sulfate pulping wastewater, adjust the pH to 3.6, aerate and stir, let stand for 40 min to settle, filter, and obtain the first filtrate; (2) Second treatment: Add 6 ppm cationic polyacrylamide to the first filtrate obtained in step (1), stir, adjust the pH to 8.0, let it stand to precipitate, filter, and obtain the effluent.

[0030] Experimental Example The color and COD of the effluent obtained in Examples 1-3 and Comparative Examples 1-5 were compared. CrThe tests included BOD5 and adsorbable organic halogens. The pollutant emission monitoring location was the company's total wastewater discharge outlet. The testing method was the dilution method for color (referencing GB / T 11903-1989), and COD... Cr Refer to GB / T 11914-1989 dichromate method, BOD5 refer to GB / T 7488-1987 dilution and inoculation method, and adsorbable organic halogens refer to GB / T 15959-1995 microcoulometric method.

[0031] The test results are shown in Table 1: Table 1. Water quality indicators of discharged water

[0032] As shown in Table 1, the effluent quality obtained after using the advanced treatment processes of Examples 1-3 is superior to that of Comparative Examples 1-5. Comparing Example 3 with Comparative Examples 1 and 3, it is evident that sodium dodecylbenzenesulfonate and chitosan play important roles in treatment agents A and B, respectively. The hydrophobic chains of sodium dodecylbenzenesulfonate can insert into the hydrophobic structural domains of lignin, reducing the surface tension of pollutant particles and causing dispersed colloidal pollutants to aggregate into large flocs. Simultaneously, it promotes the dispersibility of graphene oxide sheets, which is beneficial for the subsequent efficient removal of small-molecule organic pollutants from wastewater. The molecular chains of chitosan can connect multiple pollutant particles through bridging, enhancing the settling performance of the flocs. Comparing Example 3 with Comparative Examples 2, 4, and 5, it is clear that the absence of treatment agent A or B in the treatment process leads to ineffective removal of colloidal and organic acid components from the wastewater, reducing wastewater color and resulting in deteriorated effluent quality.

[0033] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A deep treatment process for sulfate pulping wastewater, characterized in that, Includes the following steps: (1) First treatment: Add treatment agent A to the pretreated sulfate pulping wastewater, stir, let it stand to settle, filter, and obtain the first filtrate; The treatment agent A, by weight, comprises the following components: 10-20 parts of p-toluenesulfonic acid, 10-15 parts of sodium dodecylbenzenesulfonate, 5-10 parts of tannic acid, 2-6 parts of 1,3,5-benzenetriboronic acid, 1-5 parts of graphene oxide aqueous solution, and 100-200 parts of 1,4-dioxane. (2) Second treatment: Adjust the pH of the first filtrate obtained in step (1) to 3.3~3.8, add polyferric sulfate and treatment agent B, aerate and stir, let stand to precipitate, filter, and obtain the second filtrate; The treatment agent B, by weight, comprises the following components: 10-20 parts acetic acid, 0.5-1.0 parts chitosan, 10-20 parts polyethyleneimine, 0.3-0.8 parts N6-methyladenosine, 1-5 parts sodium hydroxide, 1-5 parts hydroxylamine hydrochloride, 10-30 parts ketorolac tromethamine, and 80-150 parts water; (3) Third treatment: Add cationic polyacrylamide to the second filtrate obtained in step (2), stir, adjust the pH, let it stand to precipitate, filter, and obtain the discharged water.

2. The deep processing technology according to claim 1, characterized in that, The pretreated sulfate pulping wastewater in step (1) is obtained by sequentially passing it through a grid screen, a screen filter, and gravity sedimentation.

3. The deep processing technology according to claim 1, characterized in that, The dosage of treatment agent A is 50~100 mg / L.

4. The deep processing technology according to claim 1, characterized in that, The preparation method of the treatment agent A in step (1) includes the following steps: S1. Sodium dodecylbenzenesulfonate, p-toluenesulfonic acid and 1,4-dioxane are mixed to obtain a mixture; S2. First, add the aqueous solution of graphene oxide to the mixture and stir. Then, add tannic acid and 1,3,5-benzenetriboronic acid and react in a sealed environment at 80~120℃ to obtain a solid product. S3. Immerse the solid in anhydrous ethanol, wash with acetone, repeat 3-5 times, and vacuum dry to obtain treatment agent A.

5. The deep processing technology according to claim 4, characterized in that, The stirring time in step S2 is 25-40 min, and the sealed reaction time is 100-200 min.

6. The deep processing technology according to claim 1, characterized in that, The amount of polyferric sulfate added is 35~60 mg / L, and the amount of treatment agent B added is 100~300 mg / L.

7. The deep processing technology according to claim 1, characterized in that, The preparation method of the treatment agent B in step (2) includes the following steps: (a) Mix acetic acid, chitosan, N6-methyladenosine and sodium hydroxide, stir and then add polyethyleneimine. React at 50-60°C for 5-10 h. Wash the obtained solid product 2-3 times and dry it to obtain the modified product. (b) Mix hydroxylamine hydrochloride, ketorolac tromethamine and water, and stir for 15-25 minutes to form a soaking solution; (c) Add the modified material to the soaking solution and soak at 70~75℃ for 10~15h, wash and dry to obtain treatment agent B.

8. The deep processing technology according to claim 7, characterized in that, The solvent used for washing is 1,4-dioxane.

9. The deep processing technology according to claim 1, characterized in that, The amount of cationic polyacrylamide added is 3~10 ppm.

10. The deep processing technology according to claim 1, characterized in that, In step (3), the pH is adjusted to 7.0-8.5.

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