A production process for treating high-concentration PAM wastewater

Abstract

The present application relates to wastewater treatment technical field, specifically to a kind of production process for treating high concentration PAM wastewater, comprising the following process steps: S1.modification degradation agent is added to degrader preparation tank, then it is transported to the mixer of degradation reactor by delivery pump;S2.high concentration polyacrylamide wastewater is transported to the mixer, and after mixing is completed, degradation reaction is carried out in degradation reactor;S3.by overflow pipe overflow to the layered zone of layered concentration tank and carry out layering, the clarified water of upper layer is sent to biochemical advanced treatment system;Lower layer sludge is settled to sludge concentration area and is further concentrated, and then concentrated sludge is transported to dehydration system by concentration delivery pump.The present application greatly reduces the COD and alpha-NH3 concentration of final effluent;Polyacrylamide and microcolloid material are rapidly degraded in early production, thereby greatly reducing the viscosity of wastewater, improving the capacity and efficiency of device;Dry matter in wastewater is efficiently separated.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically a production process for treating high-concentration PAM wastewater. Background Technology

[0002] The production of polyacrylamide frequently involves polymerization reactors and curing tanks, generating large amounts of cleaning wastewater. The initial discharge contains high concentrations of polyacrylamide and its microcolloids, and due to their high viscosity, direct transport to wastewater treatment plants would be extremely difficult, resulting in low equipment efficiency and relatively high energy consumption. Currently, the industry typically treats this wastewater by diluting it with water followed by direct biochemical degradation, or by using an evaporator for concentration followed by incineration. However, both of these processes are inefficient and energy-intensive. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide a production process for treating high-concentration PAM wastewater. This invention employs a unique degradation agent system for the degradation reaction—a layered separation and concentration innovative treatment process that effectively solves the problems of existing technologies.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A production process for treating high-concentration PAM wastewater includes a process unit comprising: a degradation agent preparation tank V1, a degradation reactor R, and a stratified concentration tank V2. The degradation agent preparation tank V1 is equipped with an agitator V1-1 (r=100-200r / min), baffles V1-2 and V1-3; the degradation reactor R is equipped with an agitator R1 (r=100-200r / min), an overflow outlet R2, an overflow baffle R3, baffles R4 and R5, and a mixer R6; the stratified concentration tank V2 is equipped with a clarified water outlet V2-1, baffles V2-2, and a sludge outlet V2-5, and its main working areas are the stratification zone V2-3 and the concentration zone V2-4.

[0006] Its production process includes the following steps:

[0007] S1. Add the modified degradation agent to the degradation agent preparation tank, and then use a transfer pump to transport it to the mixer of the degradation reactor;

[0008] S2. High-concentration polyacrylamide wastewater is fed into the mixer, and after mixing, it undergoes a degradation reaction in the degradation reactor;

[0009] S3. The overflow pipe flows to the stratification zone of the stratification tank for stratification. The upper layer of clarified water goes to the biological deep treatment system to improve the quality of the effluent using biodegradation. The lower layer of sludge settles to the sludge concentration zone for further concentration. The concentrated sludge is then transported to the dewatering system via a concentration transfer pump. Sludge dewatering equipment, such as plate and frame filter press, belt filter press, or centrifugal dewatering machine, is used to form sludge cake after dewatering. The moisture content is greatly reduced and the dry matter content is increased.

[0010] The preparation of the modified degradation agent includes the following steps:

[0011] S11. By weight, mix 50-60 parts of deionized water, 7-15 parts of degradation enhancer, and 50-60 parts of iron salt, and stir at 150-200 r / min for 10-20 min.

[0012] S12. Add 8-15 parts of oxidizing agent and 10-20 parts of deionized water to the mixture obtained in step S11, and stir at a speed of 200-250 r / min for 15-20 min to obtain a preliminary modifier;

[0013] S13. Add 3-5 parts of ferric polysilicate sulfate to the preliminary modifier and ultrasonically disperse at a frequency of 40kHz for 10-15 minutes to finally obtain the modified degradation agent.

[0014] Preferably, the preparation of the degradation enhancer includes the following steps:

[0015] S111. By weight, mix 50-60 parts of deionized water and 5-10 parts of sodium citrate, and stir at 200-250 r / min for 10-15 min;

[0016] S112. Add 10-15 parts of potassium persulfate and 2-5 parts of sodium chloride to the mixture obtained in step S111, and continue stirring at 20-40℃ for 20-30 minutes to obtain a preliminary reinforcing agent;

[0017] S113. Add 0.5-2 parts of disodium ethylenediaminetetraacetate to the preliminary reinforcing agent and stir at 150-200 r / min for 10-15 min to obtain the degradation reinforcing agent.

[0018] Preferably, the preparation of the oxidizing agent includes the following steps:

[0019] S121. By weight, mix 1-3 parts of fatty alcohol polyoxyethylene ether, 50-55 parts of polydimethyldiallylammonium chloride solution, and 2-5 parts of sodium silicate, and stir at 100-150 r / min for 15-20 min.

[0020] S122. Under water bath conditions of 18-20℃ and stirring speed of 100-150r / min, slowly add 40-45 parts of hydrogen peroxide solution to the mixture obtained in step S121 to obtain an oxidizing mixture;

[0021] S123. Add 7-10 parts of deionized water to the oxidation mixture obtained in step S122, and continue stirring for 10-15 minutes to obtain the oxidation aid.

[0022] Preferably, the iron salt is composed of ferrous sulfate and ferric sulfate in a mass ratio of 0-1:1.

[0023] Preferably, the high-concentration polyacrylamide wastewater has a COD ≥ 9000 mg / L and an α-NH3 ≥ 3000 mg / L.

[0024] Preferably, the mass ratio of the modified degradation agent to the high-concentration polyacrylamide wastewater is 1-2:100.

[0025] Preferably, the degradation reaction time in the degradation reactor is 30-60 min, and the stirring speed in the degradation reactor is 100-200 r / min.

[0026] Preferably, the stirring speed of the stirrer in the degrading agent preparation tank is 100-200 r / min.

[0027] Preferably, the mass concentration of the polydimethyldiallylammonium chloride solution in step S121 is 10%.

[0028] Preferably, the mass concentration of the hydrogen peroxide solution in step S122 is 30%.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] 1. This invention significantly reduces the COD and α-NH3 concentration in the final wastewater discharge; rapidly degrades polyacrylamide and microcolloids in the early stage of production, thereby significantly reducing the viscosity of the wastewater and improving the production capacity and efficiency of the equipment; and efficiently separates dry matter from the wastewater.

[0031] 2. This invention creates a unique polyacrylamide wastewater degradation agent system, which adopts an innovative treatment process of degradation reaction-layer separation and concentration. It is more energy-efficient and efficient than the traditional process of adding water for dilution-direct biochemical degradation treatment or evaporator concentration-mixing and incineration.

[0032] 3. This invention significantly reduces wastewater viscosity and improves its flowability through the synergistic effect of oxidizing agents, degradation enhancers, and modified degradation agents, thereby enhancing the efficiency of the equipment. The COD and α-NH3 in the final clarified water decrease by approximately 90% and 75% respectively compared to the initial wastewater. This process design is novel, economically beneficial, and has strong practical value. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the apparatus for the production process of treating high-concentration PAM wastewater according to the present invention.

[0034] Figure 2 This is a process flow diagram of the production process for treating high-concentration PAM wastewater according to the present invention.

[0035] Figure 3 This is a process flow diagram for preparing the modified degradation agent of the present invention;

[0036] Figure 4 This is a process flow diagram for preparing the degradation enhancer of the present invention;

[0037] Figure 5 This is a process flow diagram for preparing the modified degradation agent of the present invention. Detailed Implementation

[0038] The present invention will now be clearly and completely described in conjunction with embodiments thereof. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0039] Please see Figure 1-5 The present invention provides a technical solution:

[0040] Example 1

[0041] A production process for treating high-concentration PAM wastewater:

[0042] Before proceeding with the production process for treating high-concentration PAM wastewater, the following steps are taken: Preparation of degradation enhancers, oxidation aids, and modified degradation agents is required.

[0043] The preparation of the degradation enhancer includes the following steps:

[0044] S111. Mix 50ml of deionized water and 5g of sodium citrate, and stir at 200r / min for 1min;

[0045] S112. Add 10g of potassium persulfate and 2g of sodium chloride to the mixture obtained in step S111, and continue stirring at 20°C for 20 minutes to obtain a preliminary reinforcing agent;

[0046] S113. Add 0.5g of disodium ethylenediaminetetraacetate to the preliminary reinforcing agent and stir at 150r / min for 10min to obtain the degradation reinforcing agent;

[0047] The preparation of oxidizing agents includes the following steps:

[0048] S121. Mix 1g of fatty alcohol polyoxyethylene ether, 50ml of 10% polydimethyldiallylammonium chloride solution, and 2g of sodium silicate, and stir at 100r / min for 15min.

[0049] S122. Under conditions of 18℃ water bath and 100r / min stirring speed, slowly add 40ml of 30% hydrogen peroxide solution to the mixture obtained in step S121 to obtain an oxidizing mixture.

[0050] S123. Add 7 ml of deionized water to the oxidation mixture obtained in step S122, and continue stirring for 10 min to obtain the oxidation aid;

[0051] The preparation of the modified degradation agent includes the following steps:

[0052] S11. Mix 50ml of deionized water, 7ml of degradation enhancer, and 50g of iron salt (composed of ferrous sulfate and ferric sulfate in a mass ratio of 0.5:1) and stir at 150r / min for 10min.

[0053] S12. Add 8 ml of oxidizing agent and 10 ml of deionized water to the mixture obtained in step S11, and stir at 200 r / min for 15 min to obtain the preliminary modifier;

[0054] S13. Add 3g of ferric polysilicate sulfate to the preliminary modifier and ultrasonically disperse at a frequency of 40kHz for 10min to finally obtain the modified degradation agent;

[0055] S1. Add 10 ml of modified degradation agent y to the degradation agent preparation tank V1. The stirring speed of the stirrer V1-1 in the degradation agent preparation tank V1 is 100 r / min. Then, it is transported to the mixer R6 of the degradation reactor R by the transfer pump P1.

[0056] S2. 1000 ml of high-concentration polyacrylamide wastewater (COD 10000 mg / l, α-NH3 3500 mg / l) is fed into mixer R6. After mixing, the wastewater is subjected to degradation reaction in degradation reactor R for 30 min. The stirring speed of stirrer R1 in degradation reactor is 100 r / min.

[0057] S3. Overflow through overflow pipe R2 to stratification tank V2 stratification zone V2-3 for stratification. The upper layer of clarified water goes to the biological deep treatment system; the lower layer of sludge settles to sludge concentration zone V2-4 for further concentration, and then the concentrated sludge is transported to the dewatering system through concentration transfer pump P2.

[0058] Example 2

[0059] A production process for treating high-concentration PAM wastewater:

[0060] Before proceeding with the production process for treating high-concentration PAM wastewater, the following steps are taken: Preparation of degradation enhancers, oxidation aids, and modified degradation agents is required.

[0061] The preparation of the degradation enhancer includes the following steps:

[0062] S111. Mix 60ml of deionized water and 10g of sodium citrate, and stir at 250r / min for 15min;

[0063] S112. Add 15g of potassium persulfate and 5g of sodium chloride to the mixture obtained in step S111, and continue stirring at 40°C for 30 minutes to obtain a preliminary reinforcing agent;

[0064] S113. Add 2g of disodium ethylenediaminetetraacetate to the preliminary reinforcing agent and stir at 200r / min for 15min to obtain the degradation reinforcing agent;

[0065] The preparation of oxidizing agents includes the following steps:

[0066] S121. Mix 3g of fatty alcohol polyoxyethylene ether, 55ml of 10% polydimethyldiallylammonium chloride solution, and 5g of sodium silicate, and stir at 150r / min for 20min.

[0067] S122. Under 20℃ water bath conditions and a stirring speed of 150r / min, slowly add 45ml of 30% hydrogen peroxide solution to the mixture obtained in step S121 to obtain an oxidizing mixture.

[0068] S123. Add 10 ml of deionized water to the oxidation mixture obtained in step S122, and continue stirring for 15 min to obtain the oxidation aid;

[0069] The preparation of the modified degradation agent includes the following steps:

[0070] S11. Mix 60ml of deionized water, 15ml of degradation enhancer, and 60g of iron salt (composed of ferrous sulfate and ferric sulfate in a mass ratio of 1:1) and stir at 200r / min for 20min.

[0071] S12. Add 15 ml of oxidizing agent and 20 ml of deionized water to the mixture obtained in step S11, and stir at 250 r / min for 20 min to obtain the preliminary modifier;

[0072] S13. Add 5g of ferric polysilicate sulfate to the preliminary modifier and ultrasonically disperse at a frequency of 40kHz for 15min to finally obtain the modified degradation agent;

[0073] S1. Add 20ml of modified degradation agent y to the degradation agent preparation tank V1. The stirring speed of the stirrer V1-1 in the degradation agent preparation tank V1 is 200r / min. Then, it is transported to the mixer R6 of the degradation reactor R by the transfer pump P1.

[0074] S2. 1000 ml of high-concentration polyacrylamide wastewater (COD 12000 mg / l, α-NH3 4000 mg / l) is fed into mixer R6. After mixing, the wastewater is degraded in degradation reactor R for 40 min. The stirring speed of stirrer R1 in degradation reactor is 200 r / min.

[0075] S3. Overflow through overflow pipe R2 to stratification tank V2 stratification zone V2-3 for stratification. The upper layer of clarified water goes to the biological deep treatment system; the lower layer of sludge settles to sludge concentration zone V2-4 for further concentration, and then the concentrated sludge is transported to the dewatering system through concentration transfer pump P2.

[0076] Example 3

[0077] A production process for treating high-concentration PAM wastewater:

[0078] Before proceeding with the production process for treating high-concentration PAM wastewater, the following steps are taken: Preparation of degradation enhancers, oxidation aids, and modified degradation agents is required.

[0079] The preparation of the degradation enhancer includes the following steps:

[0080] S111. Mix 52ml of deionized water and 6g of sodium citrate, and stir at 220r / min for 11min;

[0081] S112. Add 11g of potassium persulfate and 3g of sodium chloride to the mixture obtained in step S111, and continue stirring at 25°C for 22 minutes to obtain a preliminary reinforcing agent;

[0082] S113. Add 1g of disodium ethylenediaminetetraacetate to the preliminary reinforcing agent and stir at 170r / min for 11min to obtain the degradation reinforcing agent;

[0083] The preparation of oxidizing agents includes the following steps:

[0084] S121. Mix 1.5g fatty alcohol polyoxyethylene ether, 51ml of 10% polydimethyldiallylammonium chloride solution, and 3g sodium silicate, and stir at 120r / min for 16min.

[0085] S122. Under conditions of 19℃ water bath and 120r / min stirring speed, slowly add 41ml of 30% hydrogen peroxide solution to the mixture obtained in step S121 to obtain an oxidizing mixture;

[0086] S123. Add 8 ml of deionized water to the oxidation mixture obtained in step S122, and continue stirring for 11 min to obtain the oxidation aid;

[0087] The preparation of the modified degradation agent includes the following steps:

[0088] S11. Mix 52ml of deionized water, 9ml of degradation enhancer, and 52g of ferric sulfate, and stir at 150-200r / min for 10-20min;

[0089] S12. Add 10 ml of oxidizing agent and 12 ml of deionized water to the mixture obtained in step S11, and stir at 220 r / min for 16 min to obtain the preliminary modifier;

[0090] S13. Add 3.5g of ferric polysilicate sulfate to the preliminary modifier and ultrasonically disperse at a frequency of 40kHz for 11min to finally obtain the modified degradation agent;

[0091] S1. Add 12ml of modified degradation agent y to the degradation agent preparation tank V1. The stirring speed of the stirrer V1-1 in the degradation agent preparation tank V1 is 130r / min. Then, it is transported to the mixer R6 of the degradation reactor R by the transfer pump P1.

[0092] S2. 1000 ml of high-concentration polyacrylamide wastewater (COD 12000 mg / l, α-NH3 5000 mg / l) is fed into mixer R6. After mixing, the wastewater is subjected to degradation reaction in degradation reactor R for 45 min. The stirring speed of stirrer R1 in degradation reactor is 120 r / min.

[0093] S3. Overflow through overflow pipe R2 to stratification tank V2 stratification zone V2-3 for stratification. The upper layer of clarified water goes to the biological deep treatment system; the lower layer of sludge settles to sludge concentration zone V2-4 for further concentration, and then the concentrated sludge is transported to the dewatering system through concentration transfer pump P2.

[0094] Example 4

[0095] A production process for treating high-concentration PAM wastewater:

[0096] Before proceeding with the production process for treating high-concentration PAM wastewater, the following steps are taken: Preparation of degradation enhancers, oxidation aids, and modified degradation agents is required.

[0097] The preparation of the degradation enhancer includes the following steps:

[0098] S111. Mix 58ml of deionized water and 8g of sodium citrate, and stir at 240r / min for 14min;

[0099] S112. Add 14g of potassium persulfate and 4g of sodium chloride to the mixture obtained in step S111, and continue stirring at 35°C for 28 minutes to obtain a preliminary reinforcing agent;

[0100] S113. Add 1.5g of disodium ethylenediaminetetraacetate to the preliminary reinforcing agent and stir at 170r / min for 14min to obtain the degradation reinforcing agent;

[0101] The preparation of oxidizing agents includes the following steps:

[0102] S121. Mix 2.5g fatty alcohol polyoxyethylene ether, 54ml of 10% polydimethyldiallylammonium chloride solution, and 4g sodium silicate, and stir at 140r / min for 19min.

[0103] S122. Under conditions of 19℃ water bath and 140r / min stirring speed, slowly add 44ml of 30% hydrogen peroxide solution to the mixture obtained in step S121 to obtain an oxidizing mixture.

[0104] S123. Add 9 ml of deionized water to the oxidation mixture obtained in step S122, and continue stirring for 14 min to obtain the oxidation aid;

[0105] The preparation of the modified degradation agent includes the following steps:

[0106] S11. Mix 57ml deionized water, 13ml degradation enhancer, and 57g iron salt (composed of ferrous sulfate and ferric sulfate in a mass ratio of 0.6:1) and stir at 180r / min for 17min.

[0107] S12. Add 14 ml of oxidizing agent and 18 ml of deionized water to the mixture obtained in step S11, and stir at 240 r / min for 18 min to obtain the preliminary modifier;

[0108] S13. Add 4g of ferric polysilicate sulfate to the preliminary modifier and ultrasonically disperse at a frequency of 40kHz for 14min to finally obtain the modified degradation agent;

[0109] S1. Add 18ml of modified degradation agent y to the degradation agent preparation tank V1. The stirring speed of the stirrer V1-1 in the degradation agent preparation tank V1 is 180r / min. Then, it is transported to the mixer R6 of the degradation reactor R by the transfer pump P1.

[0110] S2. 1000 ml of high-concentration polyacrylamide wastewater (COD 12500 mg / l, α-NH3 5500 mg / l) is fed into mixer R6. After mixing, the wastewater is subjected to degradation reaction in degradation reactor R for 60 min. The stirring speed of stirrer R1 in degradation reactor is 180 r / min.

[0111] S3. Overflow through overflow pipe R2 to stratification tank V2 stratification zone V2-3 for stratification. The upper layer of clarified water goes to the biological deep treatment system; the lower layer of sludge settles to sludge concentration zone V2-4 for further concentration, and then the concentrated sludge is transported to the dewatering system through concentration transfer pump P2.

[0112] Comparative Example 1

[0113] The only difference between Comparative Example 1 and Example 1 is that the addition of the degradation enhancer is omitted in Comparative Example 1, while the remaining steps are exactly the same as in Example 1.

[0114] Comparative Example 2

[0115] The only difference between Comparative Example 2 and Example 1 is that the addition of the oxidizing agent is omitted in Comparative Example 1, while the remaining steps are exactly the same as in Example 1.

[0116] Performance testing:

[0117] Water samples were extracted before and after the process was applied. The COD removal rate, α-NH3 removal rate, and viscosity reduction rate were tested using a rapid COD analyzer, an ammonia nitrogen analyzer, and a rotational viscometer, respectively. Simultaneously, the collected sludge was weighed at 105℃ to obtain its dry matter content, and the dry matter separation efficiency was calculated. The results are shown in Table 1 below.

[0118] Table 1

[0119]

[0120] The data in the table show that this invention can efficiently degrade organic matter in wastewater and significantly reduce chemical oxygen demand. The comparative data is much lower than that of this invention, indicating that the degradation enhancer and oxidizing agent play a key role in the synergistic degradation of organic matter. Simultaneously, this invention can effectively improve wastewater flowability, which is beneficial to the operation of subsequent treatment units. The lower viscosity reduction rate in the comparative data indicates that without using a complete modified degradation agent system, it is impossible to effectively destroy PAM and its microcolloid structure, making it difficult to significantly reduce viscosity.

[0121] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A production process for treating high-concentration PAM wastewater, characterized in that, The process includes the following steps: S1. Add the modified degradation agent to the degradation agent preparation tank, and then use a transfer pump to transport it to the mixer of the degradation reactor; S2. High-concentration polyacrylamide wastewater is fed into the mixer, and after mixing, it undergoes a degradation reaction in the degradation reactor; S3. Overflow through the overflow pipe to the stratification zone of the stratification thickener for stratification, resulting in upper clarified water and lower sludge, which are then further processed; The preparation of the modified degradation agent includes the following steps: S11. By weight, mix 50-60 parts of deionized water, 7-15 parts of degradation enhancer, and 50-60 parts of iron salt, and stir at 150-200 r / min for 10-20 min. S12. Add 8-15 parts of oxidizing agent and 10-20 parts of deionized water to the mixture obtained in step S11, and stir at a speed of 200-250 r / min for 15-20 min to obtain a preliminary modifier; S13. Add 3-5 parts of ferric polysilicate sulfate to the preliminary modifier and ultrasonically disperse at a frequency of 40kHz for 10-15 minutes to finally obtain the modified degradation agent; The preparation of the degradation enhancer includes the following steps: S111. By weight, mix 50-60 parts of deionized water and 5-10 parts of sodium citrate, and stir at 200-250 r / min for 10-15 min; S112. Add 10-15 parts of potassium persulfate and 2-5 parts of sodium chloride to the mixture obtained in step S111, and continue stirring at 20-40℃ for 20-30 minutes to obtain a preliminary reinforcing agent; S113. Add 0.5-2 parts of disodium ethylenediaminetetraacetate to the preliminary reinforcing agent and stir at 150-200 r / min for 10-15 min to obtain the degradation reinforcing agent; The preparation of the oxidizing agent includes the following steps: S121. By weight, mix 1-3 parts of fatty alcohol polyoxyethylene ether, 50-55 parts of polydimethyldiallylammonium chloride solution, and 2-5 parts of sodium silicate, and stir at 100-150 r / min for 15-20 min. S122. Under water bath conditions of 18-20℃ and stirring speed of 100-150r / min, slowly add 40-45 parts of hydrogen peroxide solution to the mixture obtained in step S121 to obtain an oxidizing mixture; S123. Add 7-10 parts of deionized water to the oxidation mixture obtained in step S122, and continue stirring for 10-15 minutes to obtain the oxidation aid; The iron salt is composed of ferrous sulfate and ferric sulfate in a mass ratio of 0-1:

1. The high-concentration polyacrylamide wastewater has a COD ≥ 9000 mg / L and an α-NH3 ≥ 3000 mg / L. The mass ratio of the modified degradation agent to the high-concentration polyacrylamide wastewater is 1-2:100; The degradation reaction time in the degradation reactor is 30-60 min, and the stirring speed in the degradation reactor is 100-200 r / min.

2. The production process for treating high-concentration PAM wastewater according to claim 1, characterized in that, The stirring speed of the agitator in the degradation agent preparation tank is 100-200 r / min.

3. The production process for treating high-concentration PAM wastewater according to claim 1, characterized in that, The mass concentration of the polydimethyldiallylammonium chloride solution in step S121 is 10%.

4. The production process for treating high-concentration PAM wastewater according to claim 1, characterized in that, In step S122, the mass concentration of the hydrogen peroxide solution is 30%.

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