Wastewater treatment system for sodium methoxide production

Abstract

The invention relates to the technical field of wastewater treatment, in particular to a wastewater treatment system for sodium methoxide production, which comprises the following steps: S1, wastewater generated in sodium methoxide production flows into a pretreatment tank through a pipeline for aeration, and pretreated wastewater is obtained after treatment; s2, the pretreated wastewater continues to flow into a flocculation basin, a modified flocculant and a coagulant aid are added, and coagulated wastewater is obtained after flocculation; s3, the coagulated wastewater continues to flow to a sedimentation tank, sludge is settled to the bottom to form a sludge layer, clear water on the upper portion of the sedimentation tank enters a clear water tank in an overflow mode, and after the water quality is detected to reach the standard, centralized storage or discharge is waited. The wastewater treatment system disclosed by the invention is high in treatment efficiency, few in by-products generated in the treatment process and small in influence on the environment. Meanwhile, by recycling the sludge, the wastewater treatment cost is reduced, and the economic benefit is improved.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, in particular to a wastewater treatment system for sodium methoxide production. Background Art

[0002] Sodium methoxide (CH3ONa) is an important chemical raw material, widely used in the synthesis of intermediates such as pesticides, medicines, and dyes. The preparation methods of sodium methoxide are usually alkali preparation and metallic sodium preparation. The alkali preparation uses methanol and sodium hydroxide as raw materials to synthesize sodium methoxide products through continuous reactions. The chemical equation of the synthesis reaction is: CH3OH+NaOH→CH3ONa+H2O, in which the water generated by the reaction must be discharged in time to avoid inhibiting the continued progress of the positive reaction and inducing a reverse reaction, thereby affecting the quality and yield of the product. The high-concentration wastewater generated in the production process of sodium methoxide is mainly composed of methanol, a small amount of sodium methoxide, CODCr, BOD5, ammonia nitrogen, etc.

[0003] In the prior art, the main mechanism of action of traditional flocculants such as polyacrylamide (PAM) is to aggregate suspended matter, colloidal substances, etc. in water into larger particles through the adsorption and bridging effect of its polymer chain, so as to facilitate subsequent precipitation and filtration treatment. However, for dissolved organic matter, the adsorption and bridging effect of PAM is relatively weak, making it difficult to effectively remove. In addition, high concentrations of methanol in wastewater may interact with PAM molecules, affecting the performance of PAM, changing its molecular structure or reducing its activity, thereby affecting the flocculation effect of PAM. Summary of the invention

[0004] In order to solve the problems mentioned in the above background technology, the present invention provides a wastewater treatment system for sodium methoxide production.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A wastewater treatment system for sodium methoxide production, comprising:

[0007] S1. Wastewater generated during the production of sodium methoxide flows by gravity through a pipeline to a pretreatment tank, where the wastewater is agitated by aeration to prevent dirt from settling, thereby obtaining pretreated wastewater;

[0008] S2, the pretreated wastewater continues to flow to the flocculation tank, where modified flocculants and coagulants are added and fully mixed to form floccules, so that the suspended matter and colloidal substances in the wastewater are aggregated into larger particles, and coagulated wastewater is obtained after flocculation;

[0009] S3. The coagulated wastewater continues to flow into the sedimentation tank. The flocculants in the wastewater settle to the bottom due to gravity, forming a sludge layer. The clean water on the upper part of the sedimentation tank enters the clean water tank through overflow. After the water quality test is up to standard, it waits for centralized storage or discharge. If the water quality does not meet the standard, it returns to the flocculation tank through a pipeline. After dehydration, the sludge can be calcined at 300-400℃ to obtain the modified flocculant again, or it can be landfilled or treated as fertilizer.

[0010] Furthermore, in step S1, an aeration device is provided inside the pretreatment tank, and the residence time of the wastewater in the pretreatment tank is 30-60 minutes.

[0011] Further, the modified coagulant in step S2 is prepared by the following steps:

[0012] A1. Add ammonium sulfate and sodium sulfite to a 20-30% acrylamide solution, with ammonium persulfate as an oxidant and sodium sulfite as a reducing agent to form an oxidation-reduction initiator system. After nitrogen is introduced to remove oxygen, isopropanol and EDTA are added, with isopropanol as a chain transfer agent and EDTA as a chelating agent. The reaction system is sealed at room temperature and stirred for 1-2 hours. The temperature is then raised, sodium carboxylate is added, the pH value is adjusted to 7, and the reaction is stirred at the same speed for 2-3 hours. The product is poured into water and filtered to obtain a solid product.

[0013] A2, adding bismuth chloride to 10-20% sodium hydroxide solution, adjusting the pH value to 9-10, heating and stirring continuously for 2-3 hours to carry out hydrolysis reaction, then adding the solid product obtained in step A1, stirring at the same speed, and then controlling the reaction temperature, reacting for 4-6 hours, and vacuum drying the loaded mixture at 60° C. to constant weight to obtain a modified flocculant.

[0014] In the initial stage, ammonium sulfate and sodium sulfite act as initiators to undergo polymerization reaction with acrylamide monomers to form polyacrylamide chains. During the polymerization process, isopropanol and EDTA act as chain transfer agents and stabilizers to prevent the chain from being too long and causing the product performance to deteriorate. Sodium carboxylate forms a copolymer with the amide group on the polyacrylamide chain, namely, sodium polycarboxylate-polyacrylamide copolymer. The carboxyl and amide groups on the copolymer chain provide active sites for subsequent loading reactions. Bismuth chloride forms bismuth oxychloride colloid or microcrystals in sodium hydroxide solution. The carboxyl and amide groups on the sodium polycarboxylate-polyacrylamide copolymer chain react with the bismuth ions on the surface of the bismuth oxychloride colloid or microcrystal to form a stable loading structure.

[0015] Furthermore, in step S2, the dosage of the modified flocculant is 1-5wt% of the total mass of the sewage, the dosage of the coagulant aid is 0.05-0.1wt% of the total mass of the sewage, and the residence time of the wastewater in the flocculation tank is 1-10h.

[0016] Furthermore, the coagulant aid in step S2 includes one or more of silicate, clay, boehmite, fly ash and activated carbon.

[0017] Furthermore, in step A1, the mass ratio of ammonium sulfate, sodium sulfite, acrylamide solution, isopropanol, EDTA and sodium carboxylate is (1-2): (1.5-3): (5-6): (0.01-0.08): (0.5-0.7): (2-4).

[0018] Furthermore, the mass ratio of bismuth chloride, sodium hydroxide solution and the solid product obtained in step A1 in step A2 is (1-2): (2-4): (10-13).

[0019] Furthermore, in step A1, the heating temperature is 100-120° C., and the stirring speed is 50-100 rpm.

[0020] Furthermore, in step A2, the temperature is heated to 90-100°C, the stirring speed is 100-200 rpm, and the reaction temperature is controlled to be 60-70°C.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The present invention forms effective floccules in the flocculation tank by adding modified flocculants and coagulants. The modified flocculant molecules are in the form of long chains, on which carboxyl groups, amide groups and loaded bismuth oxychloride microcrystals or colloids are distributed. They have a large specific surface area and high surface energy, and can interact more strongly with dissolved organic matter, so that the modified flocculant can show a better flocculation effect than traditional PAM when treating wastewater containing high concentrations of methanol and dissolved organic matter.

[0023] 2. The wastewater treatment system of the present invention not only has high treatment efficiency, but also produces few by-products during the treatment process, and has little impact on the environment. At the same time, by recycling the sludge, the cost of wastewater treatment is reduced and the economic benefits are improved. DETAILED DESCRIPTION

[0024] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Unless otherwise specified, the raw materials used in the present invention are all conventional products purchased from the market.

[0026] Preparation Example 1

[0027] The modified coagulant comprises the following steps to prepare:

[0028] A1. Add 10 kg of ammonium sulfate and 15 kg of sodium sulfite to 50 kg of 20% acrylamide solution, introduce nitrogen to exclude oxygen, add 0.1 kg of isopropanol and 5 kg of EDTA, seal the reaction system at room temperature, stir at 50 rpm for 1 hour, then heat to 100 ° C, add 20 kg of sodium carboxylate, adjust the pH value to 7, stir at 50 rpm for 2 hours, pour the product into water, filter, and obtain a solid product;

[0029] A2. Add 10 kg of bismuth chloride to 20 kg of 10% sodium hydroxide solution, adjust the pH value to 9, heat to 90 ° C, and stir continuously at 100 rpm for 2 hours. Add 100 kg of the solid product obtained in step A1, stir at 100 rpm, and then control the reaction temperature to 60 ° C. The reaction is carried out for 4 hours. The loaded mixture is vacuum dried at 60 ° C to constant weight to obtain a modified flocculant.

[0030] Preparation Example 2

[0031] The modified coagulant comprises the following steps to prepare:

[0032] A1. Add 15 kg of ammonium sulfate and 20 kg of sodium sulfite to 55 kg of 25% acrylamide solution, introduce nitrogen to exclude oxygen, add 0.3 kg of isopropanol and 6 kg of EDTA, seal the reaction system at room temperature, stir at 60 rpm for 1.5 h, then heat to 110 ° C, add 30 kg of sodium carboxylate, adjust the pH value to 7, stir at 60 rpm for 2.5 h, pour the product into water, filter, and obtain a solid product;

[0033] A2. Add 15 kg of bismuth chloride to 25 kg of 15% sodium hydroxide solution, adjust the pH value to 9, heat to 95 ° C, and continue stirring at a speed of 150 rpm for 2.5 hours. Add 110 kg of the solid product obtained in step A1, stir at a speed of 150 rpm, and then control the reaction temperature to 65 ° C. The reaction is carried out for 5 hours. The loaded mixture is vacuum dried at 60 ° C to constant weight to obtain a modified flocculant.

[0034] Preparation Example 3

[0035] The modified coagulant comprises the following steps to prepare:

[0036] A1. Add 20 kg of ammonium sulfate and 30 kg of sodium sulfite to 60 kg of 30% acrylamide solution, introduce nitrogen to exclude oxygen, add 0.8 kg of isopropanol and 7 kg of EDTA, seal the reaction system at room temperature, stir continuously at 100 rpm for 2 h, then heat to 120 ° C, add 40 kg of sodium carboxylate, adjust the pH value to 7, stir at 100 rpm for 3 h, pour the product into water, filter, and obtain a solid product;

[0037] A2. Add 20 kg of bismuth chloride to 40 kg of 20% sodium hydroxide solution, adjust the pH value to 10, heat to 100 ° C, and stir continuously at 200 rpm for 3 hours. Add 130 kg of the solid product obtained in step A1, stir at 200 rpm, and then control the reaction temperature to 70 ° C. The reaction is carried out for 6 hours. The loaded mixture is vacuum dried at 60 ° C to constant weight to obtain a modified flocculant.

[0038] Example 1

[0039] A wastewater treatment system for sodium methoxide production, comprising:

[0040] S1. The wastewater generated by the production of 10t of sodium methoxide is flowed to the pretreatment tank through a pipeline and aerated by an aeration device. After 30 minutes of treatment, pretreated wastewater is obtained;

[0041] S2, the pretreated wastewater continues to flow to the flocculation tank, 1wt% of the modified flocculant prepared in Example 1 and 0.05wt% of silicic acid are added, and flocculation is performed for 1h to obtain coagulated wastewater;

[0042] S3. The coagulated wastewater continues to flow into the sedimentation tank, and the sludge settles to the bottom to form a sludge layer. The clean water on the upper part of the sedimentation tank flows into the clean water tank through overflow. After the water quality test meets the standards, it is stored centrally.

[0043] Example 2

[0044] A wastewater treatment system for sodium methoxide production, comprising:

[0045] S1. The wastewater generated by the production of 10t of sodium methoxide is flowed to the pretreatment tank through a pipeline and aerated by an aeration device. After 40 minutes of treatment, pretreated wastewater is obtained;

[0046] S2, the pretreated wastewater continues to flow to the flocculation tank, 2wt% of the modified flocculant prepared in Example 2 and 0.06wt% of boehmite are added, and coagulated wastewater is obtained after flocculation for 3h;

[0047] S3. The coagulated wastewater continues to flow into the sedimentation tank, and the sludge settles to the bottom to form a sludge layer. The clean water on the upper part of the sedimentation tank flows into the clean water tank through overflow. After the water quality test meets the standards, it is stored centrally.

[0048] Example 3

[0049] A wastewater treatment system for sodium methoxide production, comprising:

[0050] S1. The wastewater generated by the production of 10t of sodium methoxide is flowed to the pretreatment tank through a pipeline and aerated by an aeration device. After 50 minutes of treatment, pretreated wastewater is obtained;

[0051] S2, the pretreated wastewater continues to flow to the flocculation tank, 4wt% of the modified flocculant prepared in Example 3 and 0.08wt% of clay are added, and coagulated wastewater is obtained after flocculation for 6h;

[0052] S3. The coagulated wastewater continues to flow into the sedimentation tank, and the sludge settles to the bottom to form a sludge layer. The clean water on the upper part of the sedimentation tank flows into the clean water tank through overflow. After the water quality test meets the standards, it is stored centrally.

[0053] Example 4

[0054] A wastewater treatment system for sodium methoxide production, comprising:

[0055] S1. The wastewater generated by the production of 10t of sodium methoxide is flowed to the pretreatment tank through a pipeline and aerated by an aeration device. After 60 minutes of treatment, pretreated wastewater is obtained;

[0056] S2, the pretreated wastewater continues to flow to the flocculation tank, 5wt% of the modified flocculant prepared in Example 1 and 0.1wt% of activated carbon are added, and coagulated wastewater is obtained after flocculation for 10 hours;

[0057] S3. The coagulated wastewater continues to flow into the sedimentation tank, and the sludge settles to the bottom to form a sludge layer. The clean water on the upper part of the sedimentation tank flows into the clean water tank through overflow. After the water quality test meets the standards, it is stored centrally.

[0058] Comparative Example 1

[0059] The difference between this comparative example and Example 1 is that polyacrylamide (PAM) is used instead of the modified flocculant, and the remaining steps are the same as those of Example 1.

[0060] Comparative Example 2

[0061] The difference between this comparative example and Example 2 is that sodium polycarboxylate is used instead of the modified flocculant, and the remaining steps are the same as those in Example 2.

[0062] Comparative Example 3

[0063] The difference between this comparative example and Example 3 is that bismuth oxychloride is used instead of the modified flocculant, and the remaining steps are the same as those in Example 3.

[0064] Comparative Example 4

[0065] The difference between this comparative example and Example 4 is that no modified flocculant is added, and the remaining steps are the same as those of Example 4.

[0066] With reference to GB / T 18920-2020 "Water Quality of Urban Miscellaneous Water for Urban Wastewater Recycling", the water quality of Examples 1-4 and Comparative Examples 1-4 was tested, and the results are shown in Table 1:

[0067] Table 1. Water quality test results of Examples 1-4 and Comparative Examples 1-4

[0068]

[0069]

[0070] According to the initial water quality indicators of Examples 1-4 and Comparative Examples 1-4, the removal rates of the water quality indicators were calculated as shown in Table 2:

[0071] Table 2. Removal rates of Examples 1-4 and Comparative Examples 1-4

[0072]

[0073] As shown in Table 1 and Table 2, the removal rates of chemical oxygen demand (COD), ammonia nitrogen (NH3-N) and total phosphorus (TP) in Examples 1-4 are all high, all above 82%, showing the high efficiency of the modified flocculant in treating sodium methoxide production wastewater. With the increase of the dosage of the modified flocculant and the flocculation time (from Example 1 to Example 4), the removal rate does not show an obvious linear growth, indicating that within a certain range, the influence of the dosage and time on the treatment effect may reach saturation.

[0074] When polyacrylamide (PAM), sodium polycarboxylate, bismuth oxychloride were used instead of modified flocculants in Comparative Examples 1-4, or no modified flocculants were added, the removal rate was significantly reduced. The removal rate of Comparative Example 4 (without modified flocculants) was the lowest, indicating that the modified flocculants played a key role in the treatment process.

[0075] The modified flocculant may combine more effectively with soluble organic matter in wastewater through its special chemical structure to form larger flocs, which are easier to settle and remove. The chemical reaction during the modification process may enhance the adsorption capacity and bridging effect of the flocculant, making it more efficient in treating sodium methoxide production wastewater.

[0076] In summary, the modified flocculants in Examples 1-4 are highly efficient in treating wastewater from the production of sodium methoxide and can effectively treat wastewater from the production of sodium methoxide.

[0077] In the description of the specification, the description with reference to the terms "preparation example", "embodiment", "various embodiments" and the like means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or preparation example are included in at least one embodiment or preparation example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or preparation example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or preparation examples in a suitable manner.

[0078] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A wastewater treatment system for sodium methoxide production, characterized in that: include: S1. Wastewater generated by sodium methoxide production flows through a pipeline to a pretreatment tank for aeration, and pretreated wastewater is obtained after treatment; S2, the pretreated wastewater continues to flow to the flocculation tank, where modified flocculants and coagulants are added to obtain coagulated wastewater after flocculation; S3. The coagulated wastewater continues to flow into the sedimentation tank, and the sludge settles to the bottom to form a sludge layer. The clean water on the top of the sedimentation tank flows into the clean water tank through overflow. After the water quality test meets the standards, it waits for centralized storage or discharge.

2. A wastewater treatment system for sodium methoxide production according to claim 1, characterized in that: In step S1, an aeration device is provided inside the pretreatment tank, and the residence time of the wastewater in the pretreatment tank is 30-60 minutes.

3. A wastewater treatment system for sodium methoxide production according to claim 1, characterized in that: The modified coagulant in step S2 is prepared by the following steps: A1. Add ammonium sulfate and sodium sulfite to a 20-30% acrylamide solution, introduce nitrogen to remove oxygen, add isopropanol and EDTA, seal the reaction system at room temperature, continue stirring for 1-2 hours, then heat up, add sodium carboxylate, adjust the pH value to 7, stir at the same speed for 2-3 hours, pour the product into water, filter, and obtain a solid product; A2. Add bismuth chloride to 10-20% sodium hydroxide solution, adjust the pH value to 9-10, heat and continue stirring for 2-3 hours, add the solid product obtained in step A1, stir at the same speed, then control the reaction temperature, react for 4-6 hours, and vacuum dry the loaded mixture at 60° C. to constant weight to obtain a modified flocculant.

4. A wastewater treatment system for sodium methoxide production according to claim 1, characterized in that: In step S2, the dosage of the modified flocculant is 1-5wt% of the total mass of the sewage, the dosage of the coagulant aid is 0.05-0.1wt% of the total mass of the sewage, and the residence time of the wastewater in the flocculation tank is 1-10h.

5. A wastewater treatment system for sodium methoxide production according to claim 1, characterized in that: In step S2, the coagulant aid includes one or more of silicate, clay, boehmite, fly ash and activated carbon.

6. A wastewater treatment system for sodium methoxide production according to claim 1, characterized in that: In step A1, the mass ratio of ammonium sulfate, sodium sulfite, acrylamide solution, isopropanol, EDTA and sodium carboxylate is (1-2): (1.5-3): (5-6): (0.01-0.08): (0.5-0.7): (2-4).

7. A wastewater treatment system for sodium methoxide production according to claim 1, characterized in that: The mass ratio of bismuth chloride, sodium hydroxide solution and the solid product obtained in step A1 in step A2 is (1-2): (2-4): (10-13).

8. A wastewater treatment system for sodium methoxide production according to claim 1, characterized in that: In step A1, the heating temperature is 100-120° C., and the stirring speed is 50-100 rpm.

9. A wastewater treatment system for sodium methoxide production according to claim 1, characterized in that: In step A2, the temperature is heated to 90-100°C, the stirring speed is 100-200 rpm, and the reaction temperature is controlled to be 60-70°C.

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