Water treatment agent and paper mill sewage treatment method

Abstract

The invention provides a water treatment agent and a paper mill sewage treatment method. The water treatment agent comprises aluminum sulfate octadecahydrate, polyferric sulfate, hydrochloric acid and water. The water treatment agent composed of the components is applied to sewage treatment, the dosage of ferrous sulfate heptahydrate and hydrogen peroxide is reduced, and the overall dosage cost can be effectively reduced; the method comprises the following steps: hydrolyzing iron ions in the wastewater, carrying out electric neutralization with suspended and organic pollutant colloidal particles in the wastewater, carrying out adsorption bridging, complexing harmful ions and pollutants in the wastewater, destabilizing and condensing together, and precipitating, so that the effect of removing COD in advance is achieved, and the COD of the wastewater entering a Fenton system is reduced. Experimental results show that the removal rate of COD (Chemical Oxygen Demand) is 88.6 to 91.7 percent; the COD of the treated wastewater is less than or equal to 60 mg / L, the BOD is less than or equal to 20 mg / L, the pH is 6.0-9.0, the SS is less than or equal to 30 mg / L, the total phosphorus is less than or equal to 0.5 mg / L, the total nitrogen is less than or equal to 15 mg / L, and the ammonia nitrogen is less than or equal

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of wastewater treatment of pulp paper production enterprises, in particular to a water treatment agent and a pulp paper mill wastewater treatment method, and more particularly to a water treatment agent and Fenton chemical method for deep treatment of COD in wastewater. BACKGROUND

[0002] The wastewater of pulp paper production enterprises mainly comes from pulping, pulp board, white card paper, cultural paper and toilet paper, and many from the wastewater of supporting departments such as alkali recovery workshop, chemical workshop and power workshop, which leads to the complexity of the wastewater into the wastewater treatment plant and the difficulty in treatment.

[0003] The pulp papermaking wastewater mainly includes miscellaneous cells, fiber suspensions, easily degradable organic pollutants and difficult-to-degrade organic pollutants (cellulose and lignin and derivatives). The fiber suspensions and easily degradable organic pollutants are generally treated by physical precipitation and biochemical degradation, and the difficult-to-degrade organic pollutants need to be treated by deep chemical treatment (Fenton treatment).

[0004] The Fenton advanced oxidation method is to use the hydroxyl radicals generated in the system to completely mineralize the organic pollutants into water and carbon dioxide, so as to efficiently remove the difficult-to-degrade organic pollutants in the wastewater. The Fenton system needs to use ferrous sulfate heptahydrate, hydrogen peroxide and acid and alkali chemicals. The higher the content of the remaining difficult-to-degrade organic pollutants in the wastewater after biochemical treatment, the more chemicals the Fenton system needs. The comprehensive pulp papermaking enterprise produces more than 100,000 cubic meters of wastewater per day. In order to make the wastewater treatment reach the standard, the drug dosage of the Fenton system has almost reached the upper limit. SUMMARY

[0005] Therefore, the purpose of the present application is to provide a water treatment agent and a pulp paper mill wastewater treatment method, which can reduce the Fenton operation cost and improve the COD removal efficiency.

[0006] The present application provides a water treatment agent, which comprises aluminum sulfate octadecahydrate, polymeric ferric sulfate, hydrochloric acid and water.

[0007] Preferably, the mass ratio of the aluminum sulfate octadecahydrate, polymeric ferric sulfate, hydrochloric acid and water is (30.0-36.0):(8.0-12.0):(0.1-1.0):(51.0-60.0).

[0008] The present application provides a pulp paper mill wastewater treatment method, which comprises:

[0009] The wastewater treated by the secondary biological treatment is mixed with acid, and the water treatment agent described in the above technical solution is added. The wastewater after reaction is mixed with FeSO4 and hydrogen peroxide for oxidation, flocculation and air flotation, and then the pH value is adjusted to obtain the treated wastewater.

[0010] Preferably, the COD content in the wastewater after secondary biological treatment is 250–350 mg / L.

[0011] Preferably, oxidation is carried out in multiple oxidation tanks;

[0012] The FeSO4 content in a single oxidation tank is 0.075–0.085 L / s, and the hydrogen peroxide content is 0.0085–0.0095 L / s.

[0013] Preferably, the pH value of the mixture of wastewater and acid after secondary biological treatment is 3.0 to 6.0.

[0014] Preferably, the flocculant used for flocculation is PAM, and the addition amount is 0.6 to 0.75 L / s;

[0015] The pH value of the system during flocculation is 5.0 to 6.0.

[0016] Preferably, the wastewater from secondary biological treatment is obtained according to the following method:

[0017] The wastewater to be treated is aerated after physical and chemical treatment, and then subjected to secondary sedimentation to obtain wastewater with secondary biological treatment.

[0018] Preferably, the aeration temperature is 36–40°C and the dissolved oxygen content is 2.0–3.0 mg / L.

[0019] Preferably, the COD in the wastewater to be treated is 1400–1850 mg / L, the pH value is 6.0–9.0, and the temperature is 45–65℃.

[0020] This invention provides a water treatment agent comprising aluminum sulfate octadechydrate, polyferric sulfate, hydrochloric acid, and water. This invention applies the water treatment agent composed of the above components to wastewater treatment, reducing the dosage of ferrous sulfate heptahydrate and hydrogen peroxide, thus effectively lowering overall dosing costs. In wastewater, the agent hydrolyzes iron ions, neutralizing and adsorbing suspended organic pollutants in the wastewater, and destabilizing and precipitating harmful ions and pollutants, achieving early COD removal and reducing the COD of wastewater entering the Fenton system. Experimental results show that the COD removal rate is 88.6–91.7%; the treated wastewater has the following parameters: COD ≤ 60 mg / L, BOD ≤ 20 mg / L, pH = 6.0–9.0, SS ≤ 30 mg / L, total phosphorus ≤ 0.5 mg / L, total nitrogen ≤ 15 mg / L, and ammonia nitrogen ≤ 8 mg / L. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the wastewater treatment process used in an embodiment of the present invention;

[0022] Figure 2The infrared spectrum of the water treatment agent prepared in Example 1 of this invention after drying;

[0023] Figure 3 The nuclear magnetic resonance spectrum of the water treatment agent prepared in Example 1 of this invention;

[0024] Figure 4 This is a GC-MS image of the water treatment agent sample from Example 1 of the present invention after chloroform treatment;

[0025] Figure 5 The XRD pattern of the water treatment agent after drying in Example 1 of this invention;

[0026] Figure 6 MS negative ion spectrum of the water treatment agent prepared in Example 1 of this invention;

[0027] Figure 7 The IC anion spectrum of the water treatment agent prepared in Example 1 of this invention diluted approximately 1969 times. Detailed Implementation

[0028] This invention provides a water treatment agent comprising aluminum sulfate octadecylhydrate, polyferric sulfate, hydrochloric acid, and water.

[0029] The aluminum sulfate octahydrate described in this invention is prepared by the following method:

[0030] Bauxite is crushed and mixed with concentrated sulfuric acid, heated to 100-110℃ for 4-8 hours, filtered, and the filtrate is concentrated, cooled and crystallized to obtain aluminum sulfate octadecahydrate.

[0031] The bauxite described in this invention mainly contains Al2O3, and reacts with sulfuric acid as follows:

[0032] Al2O3+3H2SO4+15H2O→Al2(SO4)3·18H2O

[0033] The polyferric sulfate described in this invention is prepared by the following method:

[0034] Ferrous sulfate is dissolved in water, sulfuric acid is added to adjust the pH to 1.5–2.5, and the mixture is oxidized and matured at 50–80°C and an oxygen pressure of 0.1–0.3 MPa to obtain polyferric sulfate.

[0035] This invention introduces oxygen through an aeration device or stirring method to continuously oxidize Fe. 2+ The content is <1%; it can promote oxygen dissolution under certain pressure. In this invention, a small amount of NaNO2 is preferably added, preferably accounting for 0.1-0.5% of the mass of ferrous sulfate, as a catalyst to accelerate the oxidation reaction. In this invention, the aging time is 2-4 hours, and aging can promote the hydrolysis and polymerization of iron ions.

[0036] In this invention, the mass ratio of aluminum sulfate octadechydrate, polyferric sulfate, hydrochloric acid, and water is (30.0–36.0):(8.0–12.0):(0.1–1.0):(51.0–60.0); in specific embodiments, the composition ratio of the water treatment agent is specifically 31.0:11.0:0.20:57.8; or 33.0:10.0:0.15:56.85; or 35.5:9.0:0.25:55.25.

[0037] This invention provides a method for treating wastewater from pulp and paper mills, comprising:

[0038] Wastewater that has undergone secondary biological treatment is mixed with acid, and the water treatment agent described in the above technical solution is added. The reacted wastewater is then mixed with FeSO4 and hydrogen peroxide for oxidation, flocculation, and flotation. After adjusting the pH value, the treated wastewater is obtained.

[0039] In this invention, the COD content in the wastewater after secondary biological treatment is 250-350 mg / L; specifically, it can be 250 mg / L, 260 mg / L, 270 mg / L, 280 mg / L, 290 mg / L, 300 mg / L, 310 mg / L, 320 mg / L, 330 mg / L, 340 mg / L, or 350 mg / L.

[0040] The pH value of the wastewater and acid mixture after secondary biological treatment is 3.0–6.0. ​​The amount of water treatment agent added in this invention is controlled by a flow meter, and a dosing pump is used to pump the agent from the storage tank to the addition point. Under suitable pH conditions, the water treatment agent hydrolyzes iron ions in the wastewater, neutralizes and adsorbs colloidal particles of suspended organic pollutants in the wastewater, and destabilizes and precipitates harmful ions and pollutants in the wastewater by complexing them together.

[0041] The reacted wastewater is then mixed with FeSO4 and hydrogen peroxide for further oxidation; this oxidation is carried out in multiple oxidation tanks; the FeSO4 content in a single oxidation tank is 0.075–0.085 L / s, specifically 0.075 L / s, 0.076 L / s, 0.077 L / s, 0.078 L / s, 0.079 L / s, 0.080 L / s, 0.081 L / s, 0.082 L / s, 0.083 L / s, and 0. The concentration of FeSO4 in a single oxidation tank is 0.084 L / s or 0.085 L / s; the hydrogen peroxide content is 0.0085–0.0095 L / s, specifically 0.0085 L / s, 0.0086 L / s, 0.0087 L / s, 0.0088 L / s, 0.0089 L / s, 0.0090 L / s, 0.0091 L / s, 0.0092 L / s, 0.0093 L / s, 0.0094 L / s, or 0.0095 L / s. In a specific embodiment, the FeSO4 content in a single oxidation tank is 0.085 L / s, and the hydrogen peroxide content is 0.0095 L / s.

[0042] After oxidation, flocculation is carried out in a flocculation tank using PAM as the flocculant. The addition rate is 0.6–0.75 L / s, specifically 0.6 L / s, 0.61 L / s, 0.62 L / s, 0.63 L / s, 0.64 L / s, 0.65 L / s, 0.66 L / s, 0.67 L / s, 0.68 L / s, 0.69 L / s, 0.70 L / s, 0.71 L / s, 0.72 L / s, 0.73 L / s, 0.74 L / s, or 0.75 L / s. NaOH is added to the flocculation tank to adjust the pH value, preferably to 5–6. In a specific embodiment, the addition rate of PAM is 0.68 L / s, and the pH value is 5.7.

[0043] After flocculation, the wastewater enters the dissolved air flotation (DAF) tank for flotation. DAF removes color from the water and reduces COD and SS in the wastewater. The water treated in the flocculation tank enters the DAF tank, where it is thoroughly mixed with the air-water mixture generated by the dispersion pump in the dispersion chamber. It then enters the DAF tank from the center, where the sludge in the wastewater combines with the air bubbles. With the help of the buoyancy generated by the tiny bubbles, the suspended solids in the water rise to the surface, forming surface DAF sludge. This surface sludge is scraped by a scraper into the DAF sludge well and then flows into the chemical sludge tank. A small amount of bottom sludge is scraped by a bottom scraper into the chemical sludge tank, completing the sludge-water separation process.

[0044] The water treated by the flotation tank is weakly acidic. It is preferable to add NaOH to adjust the pH value to 6.0-9.0, specifically 6.0, 6.5, 7.0, 7.5, 8.0, 8.5 or 9.0.

[0045] The wastewater undergoing secondary biological treatment as described in this invention is preferably obtained according to the following method:

[0046] The wastewater to be treated is aerated after physical and chemical treatment, and then subjected to secondary sedimentation to obtain wastewater with secondary biological treatment.

[0047] This invention preferably employs two aeration tanks for aeration; the wastewater treated in the aeration tanks then separately enters secondary sedimentation tanks. The aeration temperature in this invention is 36–40°C, specifically 36°C, 36.5°C, 37°C, 37.5°C, 38°C, 38.5°C, 39°C, 39.5°C, or 40°C; the dissolved oxygen content is 2.0–3.0 mg / L, specifically 2.0 mg / L, 2.1 mg / L, 2.2 mg / L, 2.3 mg / L, 2.4 mg / L, 2.5 mg / L, 2.6 mg / L, 2.7 mg / L, 2.8 mg / L, 2.9 mg / L, or 3.0 mg / L. In a specific embodiment, the temperatures in the aeration tanks are 39.3°C and 39.5°C, respectively; the dissolved oxygen contents are 2.3 mg / L and 2.4 mg / L, respectively.

[0048] The process of physical and chemical treatment of the wastewater in this invention includes:

[0049] The wastewater to be treated is passed through a manual screen and then a mechanical screen, then through an inlet pumping station, and after heat exchange, it enters a distribution well, then undergoes primary sedimentation in a sedimentation tank, and finally enters a neutralization tank to obtain wastewater after primary physicochemical treatment.

[0050] In this invention, the wastewater to be treated has a COD content of 1400–1850 mg / L, a pH value of 6.0–9.0, and a temperature of 45–65°C. In a specific embodiment, the wastewater to be treated has a COD content of 1446 mg / L, a pH value of 7.16, and a temperature of 58.0°C. This invention introduces wastewater from secondary alkali recovery, chemical treatment, and secondary pulping / plate making into the inlet channel.

[0051] In this invention, the mechanical bar has a gap of 12mm to remove larger debris. This invention preferably uses a cooling tower for heat exchange, ensuring the wastewater temperature after heat exchange is below 38℃.

[0052] This invention preferably employs two primary sedimentation tanks, which are used to settle suspended sludge and reduce SS (suspended solids). Acid is added to the neutralization tank to adjust the pH to 6.5–7.5; the temperature in the neutralization tank is 36–38°C.

[0053] The wastewater treatment method for pulp and paper mills provided by this invention includes three-stage treatment: primary treatment is physicochemical treatment; secondary treatment is biological treatment; and tertiary treatment is decolorization treatment.

[0054] This invention treats wastewater from various workshops in the factory by first-stage physicochemical treatment and second-stage biological treatment to remove most of the COD, SS and other substances. Then, in the third-stage decolorization treatment, the wastewater undergoes pretreatment with a high-efficiency water treatment agent, pH adjustment, Fenton oxidation treatment, flocculation, and flotation sludge scraping, and finally the wastewater is treated to discharge into the sea.

[0055] After treatment using the above process, the wastewater has the following properties: COD ≤ 60 mg / L, BOD ≤ 20 mg / L, pH 6.0–9.0, SS ≤ 30 mg / L, total phosphorus ≤ 0.5 mg / L, total nitrogen ≤ 15 mg / L, and ammonia nitrogen ≤ 8 mg / L.

[0056] This invention, through process optimization and the addition of water treatment agents, and by controlling the treated discharge indicators to meet national standards, significantly reduces the consumption of chemicals such as ferrous sulfate heptahydrate, hydrogen peroxide, and sodium hydroxide used in the Fenton system, greatly reducing the operating cost of the Fenton treatment system. The overall operating cost of the Fenton treatment system is reduced by approximately 34.65%, and the original bottleneck in wastewater treatment is broken, significantly increasing the amount of wastewater that can be treated and promoting environmental protection.

[0057] This invention optimizes the Fenton process by reducing the dosage of ferrous sulfate heptahydrate and hydrogen peroxide: the dosage of ferrous sulfate heptahydrate and hydrogen peroxide in the Fenton treatment system directly affects the COD removal efficiency. Higher dosages of ferrous sulfate heptahydrate and hydrogen peroxide are beneficial for improving COD removal efficiency. However, by adding a small amount of the aforementioned high-efficiency, low-cost water treatment agent in advance, a high COD removal efficiency can be maintained even with lower dosages of ferrous sulfate heptahydrate and hydrogen peroxide. By adjusting the dosage ratio of the aforementioned high-efficiency water treatment agent, ferrous sulfate heptahydrate, and hydrogen peroxide, the overall dosing cost can be effectively reduced.

[0058] The process provided by this invention improves the bypass of secondary sedimentation water and reduces the cost of alkali for pH adjustment before flocculation: After the efficiency of the Fenton treatment system is improved, while ensuring low dosage, the COD value of the water leaving the Fenton system is low, which can reduce the amount of water entering the Fenton system, increase the bypass ratio of secondary sedimentation water, and neutralize the Fenton effluent through the high pH value of the secondary sedimentation water, thereby reducing the consumption of NaOH for pH adjustment before flocculation and thus reducing the overall treatment cost of the system.

[0059] To further illustrate the present invention, the following detailed description of a water treatment agent and a pulp and paper mill wastewater treatment method provided by the present invention is provided in conjunction with embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0060] Example 1

[0061] Preparation process of water treatment agent: Mix 33g of aluminum sulfate octadechydrate, 10g of polyferric sulfate, 0.15g of hydrochloric acid and 56.85mL of water to obtain water treatment agent; the actual usage is about 100 to 150 tons per day according to this ratio.

[0062] use Figure 1 The flowchart is as follows:

[0063] In this embodiment, wastewater from the second-phase alkali recovery, chemical treatment, and second-phase pulping and pulp board production is fed into the inlet channel. The wastewater to be treated has a COD content of 1446 mg / L, a pH value of 7.16, and a temperature of 58.0℃.

[0064] Primary treatment: The wastewater to be treated is passed through a manual screen and then through a mechanical screen to remove larger impurities. It then passes through the influent pumping station, and after heat exchange, the temperature drops to 36.7℃. After heat exchange, it enters the distribution well, then undergoes primary sedimentation in the sedimentation tank, and finally enters the neutralization tank to obtain the wastewater after primary physicochemical treatment. At this time, the wastewater has a COD content of 1220mg / L, a pH value of 6.72, and a temperature of 39.3℃.

[0065] Secondary treatment: Two aeration tanks are used for aeration; the wastewater treated in the aeration tanks then enters secondary sedimentation tanks for sludge-water separation. In this embodiment, the aeration temperatures are 39.3℃ and 39.5℃, respectively, and the dissolved oxygen contents are 2.3 mg / L and 2.4 mg / L, respectively. The COD of the effluent from the secondary sedimentation tanks are 255 mg / L and 257 mg / L, respectively.

[0066] Tertiary treatment: In this embodiment, the COD content of the wastewater after secondary biological treatment is 256 mg / L; the pH value of the wastewater and acid mixture after secondary biological treatment is 5.03. The amount of water treatment agent added in this invention is 1.14 L / s. The reacted wastewater is then mixed with FeSO4 and hydrogen peroxide for oxidation; the oxidation is carried out in multiple oxidation tanks; the FeSO4 content in a single oxidation tank is 0.085 L / s, and the hydrogen peroxide content is 0.0095 L / s (when no water treatment agent is added: the FeSO4 content in a single oxidation tank is 0.3827 L / s, and the hydrogen peroxide content is 0.0437 L / s), and the COD of the oxidized wastewater is 22 mg / L. At this time, the COD removal rate of Fenton oxidation treatment is 91.46%.

[0067] The oxidized wastewater undergoes flocculation in a flocculation tank, using PAM flocculant at a dosage of 0.68 L / s. Secondary sedimentation effluent is mixed in the flocculation tank, and NaOH is added to adjust the pH to 5.7. After flocculation, the wastewater enters a dissolved air flotation (DAF) tank for further treatment. The treated water is weakly acidic, and NaOH is added to adjust the pH to 6.3. The treated wastewater exhibits the following parameters: COD 45.2 mg / L, BOD ≤ 15 mg / L, pH 6.3, SS ≤ 13 mg / L, total phosphorus ≤ 0.02 mg / L, total nitrogen ≤ 5.77 mg / L, and ammonia nitrogen ≤ 0.41 mg / L.

[0068] Figure 2 The infrared spectrum of the water treatment agent prepared in Example 1 of this invention after drying; from Figure 2 It can be known that:

[0069] 600cm -1 The nearby peaks are characteristic peaks of the symmetric stretching vibration of aluminum ions (Al3+);

[0070] 1160cm -1 The nearby peaks are symmetric stretching vibration peaks of sulfate ions (SO42-);

[0071] 1630cm -1 The nearby peaks are characteristic peaks of water of crystallization; the above infrared peak analysis indicates that the compound contains aluminum ions (Al3+) and sulfate ions (SO42-) and contains water of crystallization, which is consistent with the aluminum sulfate octahydrate component in water treatment agents.

[0072] Depend on Figures 3 to 7 The characterization diagram and the test data in Table 1 comprehensively prove that the main components of this water treatment agent are aluminum sulfate octadecylhydrate and polyferric sulfate.

[0073] Table 1. XRF test data of the original water treatment agent

[0074] [C6H 10 O5]]> 940 271 mg / L S 339 82 mg / L Al 223 45 mg / L Fe 216 7 mg / L Cl 512 mg / L P 202 mg / L Ca 199 mg / L Mg 166 mg / L Na 157 mg / L

[0075] As shown in the above embodiments, this invention provides a water treatment agent comprising aluminum sulfate octadecahydrate, polyferric sulfate, hydrochloric acid, and water. This invention applies the water treatment agent composed of the above components to wastewater treatment, reducing the dosage of ferrous sulfate heptahydrate and hydrogen peroxide, effectively lowering the overall dosing cost. In wastewater, the agent hydrolyzes iron ions, neutralizing and adsorbing suspended organic pollutants in the wastewater, and destabilizing and precipitating harmful ions and pollutants, thus achieving early COD removal and reducing the COD of wastewater entering the Fenton system. Experimental results show that the COD removal rate is 91.4%; the treated wastewater has the following parameters: COD ≤ 60 mg / L, BOD ≤ 20 mg / L, pH = 6.0-9.0, SS ≤ 30 mg / L, total phosphorus ≤ 0.5 mg / L, total nitrogen ≤ 15 mg / L, and ammonia nitrogen ≤ 8 mg / L.

[0076] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A water treatment agent comprising aluminum sulfate octadechydrate, polyferric sulfate, hydrochloric acid, and water.

2. The water treatment agent according to claim 1, characterized in that, The mass ratio of aluminum sulfate octadechydrate, polyferric sulfate, hydrochloric acid, and water is (30.0–36.0):(8.0–12.0):(0.1–1.0):(51.0–60.0).

3. A method for treating wastewater from a pulp and paper mill, comprising: Wastewater that has undergone secondary biological treatment is mixed with acid, and the water treatment agent described in any one of claims 1 to 2 is added. The reacted wastewater is then mixed with FeSO4 and hydrogen peroxide for oxidation, flocculation, and air flotation, and the pH value is adjusted to obtain treated wastewater.

4. The pulp and paper mill wastewater treatment method according to claim 3, characterized in that, The COD content in the wastewater that has undergone secondary biological treatment is 250–350 mg / L.

5. The pulp and paper mill wastewater treatment method according to claim 3, characterized in that, Oxidation is carried out in multiple oxidation tanks; The FeSO4 content in a single oxidation tank is 0.075–0.085 L / s, and the hydrogen peroxide content is 0.0085–0.0095 L / s.

6. The pulp and paper mill wastewater treatment method according to claim 3, characterized in that, The pH value of the mixture of wastewater and acid after secondary biological treatment is 3.0 to 6.

0.

7. The pulp and paper mill wastewater treatment method according to claim 3, characterized in that, The flocculant used for flocculation is PAM, and the addition rate is 0.6–0.75 L / s; The pH value of the system during flocculation is 5.0 to 6.

0.

8. The wastewater treatment method for pulp and paper mills according to claim 3, characterized in that, Wastewater treated by secondary biological processes is obtained through the following methods: The wastewater to be treated is aerated after physical and chemical treatment, and then subjected to secondary sedimentation to obtain wastewater with secondary biological treatment.

9. The wastewater treatment method for pulp and paper mills according to claim 8, characterized in that, The aeration temperature is 36–40℃, and the dissolved oxygen content is 2.0–3.0 mg / L.

10. The pulp and paper mill wastewater treatment method according to claim 8, characterized in that, The wastewater to be treated has a COD of 1400–1850 mg / L, a pH of 6.0–9.0, and a temperature of 45–65℃.

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