Hydroxypropyl methyl cellulose production wastewater treatment system

Abstract

The utility model discloses a hydroxypropyl methyl cellulose production wastewater treatment system which comprises an adjusting tank, a hydrolysis acidification tank, a hydrolysis sedimentation tank, a UASB (Upflow Anaerobic Sludge Blanket) anaerobic reactor, an A / O (Anaerobic / Oxic) tank, a secondary sedimentation tank, a facultative tank, a biological contact oxidation tank, an intermediate sedimentation tank, a third-stage reaction tank, a final sedimentation tank and a clean water tank which are communicated in sequence, the low-concentration wastewater collecting tank and the high-concentration wastewater collecting tank are communicated with the regulating tank. By mixing low-concentration wastewater and high-concentration wastewater, the salt concentration of the wastewater is reduced, the inhibition on microbial activity is reduced, and the treatment efficiency is improved; through hydrolytic acidification and UASB anaerobic reaction, the degradation process of organic matters is enhanced, and the biodegradability and treatment efficiency of the wastewater are improved; organic matters, nitrogen elements and particulate matters are removed through A / O treatment, biological contact oxidation and coagulating sedimentation; the advantages of each process are fully exerted, the treatment efficiency and the standard-reaching rate of water quality are improved, and environmental protection and energy conservation are realized.

Description

Technical Field

[0001] The utility model relates to the technical field of wastewater treatment, in particular to a wastewater treatment system for the production of hydroxypropyl methyl cellulose. Background Art

[0002] Cellulose ether is a compound soluble in water with a high molecular weight. It is a general term for a class of products obtained from natural cellulose as raw materials, using sodium hydroxide, chloromethane, propylene oxide, etc. as solvents and etherifying agents through a series of reactions. Cellulose ethers include ionic products such as carboxymethyl cellulose (CMC), and non-ionic products such as hydroxypropyl methyl cellulose (HPMC) and methyl cellulose (MC). Hydroxypropyl methyl cellulose (HPMC) is a product obtained by substituting some methoxy groups in methyl cellulose with hydroxypropoxy groups. It is a white, odorless, and non-toxic powdery substance, but it is difficult to degrade and will not be nitrified or decomposed in the human body. HPMC is soluble in water, and its aqueous solution is colorless, transparent, and viscous. It is also soluble in ethanol, acetone, etc. Hydroxypropyl methyl cellulose is a non-ionic cellulose mixed ether with excellent performance and is widely used.

[0003] However, wastewater is generated during the production of hydroxypropyl methyl cellulose, including high-concentration organic wastewater such as kettle washing wastewater and separation and purification wastewater, and low-concentration wastewater such as product washing wastewater, workshop cleaning water, and steam condensate. The high-concentration organic wastewater mainly contains reaction products such as cellulose raw materials, cellulose ether, and sodium chloride, unreacted etherifying agents chloromethane and propylene oxide, and reaction intermediates and by-products such as methanol, ethyl ether, and propanol. It has the characteristics of high COD concentration, lack of nutrients, and high salt content inhibiting microbial degradation. It belongs to high-concentration and high-salt organic wastewater, and the wastewater treatment is difficult.

[0004] The existing wastewater treatment system for the production of hydroxypropyl methyl cellulose has low treatment efficiency. Because the pollutants in the hydroxypropyl methyl cellulose wastewater are mainly organic substances and salts such as sodium chloride, its salt content is extremely high, up to 70,000 - 80,000 mg / L at most, and the mass concentration reaches 3% - 7%. The high salinity will inhibit the activity of microorganisms, making the biological treatment process difficult to carry out, thus affecting the overall wastewater treatment effect. In addition, the existing treatment system has a high operating cost. In order to cope with the challenges of high salinity and refractory organic substances, the wastewater treatment system adopts more complex treatment processes and more chemicals, such as a large amount of chemical agents and high-energy-consuming equipment (such as evaporators, advanced oxidation equipment, etc.), significantly increasing the operating cost of wastewater treatment. Summary of the Invention

[0005] The technical problem to be solved by the present utility model is to provide a wastewater treatment system for the production of hydroxypropyl methylcellulose. By mixing low-concentration wastewater and high-concentration wastewater to adjust the salt concentration of the wastewater, the inhibition of microbial activity is reduced. The HPMC wastewater is treated by combining hydrolysis acidification, UASB anaerobic reaction, A / O treatment, biological contact oxidation and coagulation sedimentation, giving full play to the advantages of each process, improving the treatment efficiency and the compliance rate of water quality, and avoiding the problems of high-salinity inhibition of microbial activity and high operating costs caused by using high-energy-consuming equipment.

[0006] To solve the above technical problem, the present utility model provides a wastewater treatment system for the production of hydroxypropyl methylcellulose, which is characterized in that it includes a regulating tank, a hydrolysis acidification tank, a hydrolysis sedimentation tank, a UASB anaerobic reactor, an A / O tank, a secondary sedimentation tank, an anoxic tank, a biological contact oxidation tank, an intermediate sedimentation tank, a three-stage reaction tank, a final sedimentation tank and a clear water tank connected in sequence, and also includes a low-concentration wastewater collection tank and a high-concentration wastewater collection tank connected to the regulating tank.

[0007] The present utility model uses a low-concentration wastewater collection tank to collect low-concentration wastewater such as domestic sewage, workshop cleaning water, product washing wastewater, steam condensate, initial rainwater, etc., and a high-concentration wastewater collection tank to collect high-concentration process wastewater including kettle washing wastewater and separation and purification wastewater. The low-concentration wastewater and the high-concentration wastewater are pumped into the regulating tank to reduce the salt content in the wastewater and the inhibition of microbial activity. After the wastewater is homogenized and equalized in the regulating tank, it enters the hydrolysis acidification tank, the hydrolysis sedimentation tank and the UASB anaerobic reactor in sequence.

[0008] The wastewater undergoes anaerobic reaction in the hydrolysis acidification tank, including two stages: hydrolysis and acidification. In the hydrolysis stage, acid-producing bacteria secrete extracellular hydrolytic enzymes to convert macromolecular, complex non-dissolved organic substances that are difficult to be directly utilized by anaerobic bacteria into simple dissolved organic monomers or dimers, and at the same time synthesize new cell bodies. For example, macromolecular cellulose ether is hydrolyzed into small-molecule organic substances such as glucose, fructose and other oligosaccharides under the action of hydrolytic enzymes, and propylene oxide undergoes ring-opening reaction under the action of hydrolytic enzymes to generate propanol, etc. In the acidification stage: small-molecule organic substances such as sugars, propanol, methanol, and ether including the above hydrolysis products act as both electron donors and electron acceptors, and are converted into volatile fatty acids (VFA) such as formic acid, acetic acid, propionic acid, and butyric acid, as well as products such as ethanol, carbon dioxide, and H2 under the action of acid-producing fermentation bacteria, and at the same time synthesize new cells in the biotransformation process. The wastewater enters the hydrolysis sedimentation tank to achieve mud-water separation, and the supernatant enters the UASB anaerobic reactor to continue the anaerobic reaction, hydrolysis, acidification, and anaerobic reactions of hydrogen production, acetic acid production and methane production occur, strengthening the degradation process of organic substances through hydrolysis acidification and UASB anaerobic reaction, and improving the biodegradability and treatment efficiency of the wastewater.

[0009] The effluent of the UASB anaerobic reactor flows into the A / O pool automatically for nitrification-denitrification reaction to remove organic matter and nitrogen in the wastewater. After the sludge-water separation is completed in the secondary sedimentation tank, the effluent flows into the anoxic-oxic pool and the biological contact oxidation pool in sequence. After screening anoxic and anaerobic microorganisms in the anoxic-oxic pool and conducting denitrification reaction, the organic matter is further removed under the action of the biofilm with a stepped oxygen concentration distribution in the biological contact oxidation pool, and the nitrification-denitrification process is completed to remove nitrogen. The effluent flows into the tertiary reaction pool and the final sedimentation tank after sedimentation in the intermediate sedimentation tank. Coagulation reaction occurs to the organic matter, colloid, particulate matter, etc. in the wastewater, so that the pollutants settle as sludge, and the supernatant enters the clear water tank.

[0010] Furthermore, it also includes a biochemical sludge thickening tank;

[0011] The sludge discharge port of the hydrolysis sedimentation tank is divided into two paths. One path is connected to the hydrolysis acidification tank, and the other path is connected to the biochemical sludge thickening tank; part of the precipitated sludge is refluxed to the hydrolysis acidification tank to supplement the lost strains;

[0012] The sludge discharge port of the secondary sedimentation tank is divided into two paths. One path is connected to the A / O pool, and the other path is connected to the biochemical sludge thickening tank; the precipitated sludge is refluxed to the front end of the A / O pool to supplement the lost strains;

[0013] The sludge discharge port of the intermediate sedimentation tank is divided into two paths. One path is connected to the anoxic-oxic pool, and the other path is connected to the biochemical sludge thickening tank; after the effluent biofilm and suspended sludge are precipitated, they are refluxed to the anoxic-oxic pool to supplement the lost microbial quantity of the system.

[0014] Furthermore, it also includes a physicochemical sludge pool, and the physicochemical sludge pool is connected to the bottom sludge discharge port of the final sedimentation tank.

[0015] Furthermore, an intermediate water tank is also arranged between the hydrolysis sedimentation tank and the UASB anaerobic reactor.

[0016] Furthermore, the A / O pool includes an anoxic tank and an aerobic tank. The water outlet of the anoxic tank is connected to the water inlet of the aerobic tank, and the bottom of the aerobic tank is connected to the anoxic tank through a nitrification liquid reflux pipe. The denitrification and nitrogen removal tank (anoxic tank) is arranged before the carbon removal and nitrification (aerobic tank) to directly utilize the organic carbon source in the influent water, and through the large-scale reflux of the aerobic tank mixed liquor to the anoxic tank, the NOx-N in it undergoes denitrification in the anoxic tank. While having the nitrogen removal function, it fully utilizes the organic matter in the wastewater, and has the advantages of short process and low cost compared with the traditional multi-stage nitrification / denitrification process.

[0017] Furthermore, bottle-brush-shaped elastic three-dimensional fiber fillers are arranged in the hydrolysis acidification tank.

[0018] Furthermore, a combined filler of polyethylene disk plates and synthetic fiber bundles is arranged in the anoxic-oxic pool and the biological contact oxidation pool.

[0019] Further, the final sedimentation tank is an inclined plate sedimentation tank, and inclined tubes, inclined plates and honeycomb fillers are arranged in the tank body.

[0020] Further, the secondary sedimentation tank is a radial flow sedimentation tank, and the hydrolysis sedimentation tank and the intermediate sedimentation tank are vertical flow sedimentation tanks.

[0021] Further, microporous aeration modules are arranged in both the aerobic tank and the biological contact oxidation tank.

[0022] Advantages of the utility model:

[0023] The utility model reduces the salt concentration of the wastewater by mixing the wastewater in the low-concentration wastewater collection tank and the high-concentration wastewater collection tank, reduces the inhibition of the microbial activity, and improves the treatment efficiency; through hydrolysis acidification and UASB anaerobic reaction, the degradation process of organic matter is strengthened, and the biodegradability and treatment efficiency of the wastewater are improved; through A / O treatment, biological contact oxidation and coagulation sedimentation, the remaining organic matter, nitrogen elements and particulate matters are removed; the advantages of each process are fully exerted, the treatment efficiency and the water quality compliance rate are improved, environmental protection and energy conservation are achieved, and the problems of high salt concentration inhibiting microbial activity and high operating cost caused by using high-energy-consuming equipment are avoided. Description of the drawings

[0024] Figure 1 is a schematic structural diagram of the treatment system for hydroxypropyl methylcellulose production wastewater of the utility model;

[0025] Explanation of the reference numerals in the figure: 1, regulating tank; 2, hydrolysis acidification tank; 3, hydrolysis sedimentation tank; 4, UASB anaerobic reactor; 5, secondary sedimentation tank; 6, facultative oxygen tank; 7, biological contact oxidation tank; 8, intermediate sedimentation tank; 9, tertiary reaction tank; 10, final sedimentation tank; 11, clear water tank; 12, low-concentration wastewater collection tank; 13, high-concentration wastewater collection tank; 14, biochemical sludge thickening tank; 15, physical and chemical sludge tank; 17, intermediate water tank; 18, anoxic tank; 19, aerobic tank. Specific embodiments

[0026] The following further illustrates the utility model in conjunction with the drawings and specific embodiments, so that those skilled in the art can better understand the utility model and be able to implement it, but the embodiments given are not intended to limit the utility model.

[0027] Refer to Figure 1As shown in the figure, the utility model provides a wastewater treatment system for hydroxypropyl methylcellulose production, which is characterized by including a regulating tank 1, a hydrolysis acidification tank 2, a hydrolysis sedimentation tank 3, a UASB anaerobic reactor 4, an A / O tank, a secondary sedimentation tank 5, an anoxic tank 6, a biological contact oxidation tank 7, an intermediate sedimentation tank 8, a three-stage reaction tank 9, a final sedimentation tank 10 and a clear water tank 11, which are connected in sequence. It also includes a low-concentration wastewater collection tank 12 and a high-concentration wastewater collection tank 13 connected to the regulating tank 1. It also includes a biochemical sludge thickening tank 14; the sludge discharge port of the hydrolysis sedimentation tank 3 is divided into two paths, one path is connected to the hydrolysis acidification tank 2, and the other path is connected to the biochemical sludge thickening tank 14; the sludge discharge port of the secondary sedimentation tank 5 is divided into two paths, one path is connected to the A / O tank, and the other path is connected to the biochemical sludge thickening tank 14; the sludge discharge port of the intermediate sedimentation tank 8 is divided into two paths, one path is connected to the anoxic tank 6, and the other path is connected to the biochemical sludge thickening tank 14; it also includes a physical and chemical sludge tank 15, and the physical and chemical sludge tank 15 is connected to the bottom sludge discharge port of the final sedimentation tank 10.

[0028] Preferably, an intermediate water tank 17 is also provided between the hydrolysis sedimentation tank 3 and the UASB anaerobic reactor 4. The A / O tank includes an anoxic tank 18 and an aerobic tank 19. The water outlet of the anoxic tank 18 is connected to the water inlet of the aerobic tank 19, and the bottom of the aerobic tank 19 is connected to the anoxic tank 18 through a nitrification liquid reflux pipe.

[0029] Preferably, bottle-brush-shaped elastic three-dimensional fiber fillers are arranged in the hydrolysis acidification tank 2, and a combined filler of polyethylene disc plates and synthetic fiber bundles is arranged in the anoxic tank 6 and the biological contact oxidation tank 7.

[0030] Preferably, the final sedimentation tank is an inclined plate sedimentation tank, and inclined tubes, inclined plates and honeycomb fillers are arranged in the tank body. The secondary sedimentation tank is a radial flow sedimentation tank. The hydrolysis sedimentation tank 3 and the intermediate sedimentation tank 8 are vertical flow sedimentation tanks. Micro-pore aeration modules are arranged in both the aerobic tank 19 and the biological contact oxidation tank 7.

[0031] The working process of the wastewater treatment system for hydroxypropyl methylcellulose production of the utility model is as follows:

[0032] The low-concentration wastewater collection tank 12 collects low-concentration wastewater such as domestic sewage, workshop cleaning water, product washing wastewater, steam condensate, and initial rainwater. The low-concentration wastewater and the high-concentration production process wastewater in the high-concentration wastewater collection tank 13, including kettle washing wastewater and separation and purification wastewater, are pumped into the regulating tank 1 to reduce the salt content in the wastewater to 3000 mg / L, greatly reducing the inhibition of microbial activity. After the wastewater is homogenized and equalized in the regulating tank 1, it sequentially enters the hydrolysis acidification tank 2, the hydrolysis sedimentation tank 3 and the UASB anaerobic reactor 4.

[0033] The wastewater undergoes an anaerobic reaction under anaerobic conditions (dissolved oxygen not higher than 0.1 mg / L) in the hydrolysis acidification tank 2, including two stages: hydrolysis and acidification. In the hydrolysis stage, acid-producing bacteria secrete extracellular hydrolytic enzymes to convert macromolecular, complex non-dissolved organic substances that are difficult to be directly utilized by anaerobic bacteria into simple dissolved organic monomers or dimers, and at the same time synthesize new cell bodies. For example, macromolecular cellulose ether is hydrolyzed into small molecule organic substances such as glucose, fructose, and other oligosaccharides under the action of hydrolytic enzymes, and propylene oxide undergoes a ring-opening reaction under the action of hydrolytic enzymes to generate propanol, etc. In the acidification stage: small molecule organic substances such as sugars, propanol, methanol, and ether, including the above hydrolysis products, act as both electron donors and electron acceptors, and are converted into volatile fatty acids (VFA) such as formic acid, acetic acid, propionic acid, and butyric acid, as well as products such as ethanol, carbon dioxide, and H2 under the action of acid-producing fermentation bacteria, and at the same time synthesize new cells in the process of biological transformation.

[0034] The water in the hydrolysis acidification tank 2 enters the hydrolysis sedimentation tank 3 to achieve mud-water separation. The supernatant enters the UASB anaerobic reactor 4 to continue the anaerobic reaction under anaerobic conditions (dissolved oxygen not higher than 0.1 mg / L), including hydrolysis, acidification, and anaerobic reactions of hydrogen production, acetic acid production, and methane production. The anaerobic reaction is complete: in the hydrogen-producing acetic acid stage, under the action of hydrogen-producing acetic acid bacteria (HPA), organic acids with more than 2 carbon atoms such as propionic acid and butyric acid, and ethanol, etc. are converted into CH3COOH, H2CO3, CO2, and H2, and at the same time synthesize new cells in the process of biological transformation; in the methane production stage, under the action of methane-producing bacteria, H2CO3, CH3COOH, CH3OH, H2, etc. are converted into substances such as CH4, CO2, and H2O. The degradation process of organic substances is strengthened through hydrolysis acidification and UASB anaerobic reactions, and the biodegradability and treatment efficiency of the wastewater are improved.

[0035] The effluent of the UASB anaerobic reactor 4 flows into the A / O tank by gravity for nitrification-denitrification reaction. Among them, the dissolved oxygen in the anoxic tank 18 is 0.2 - 0.6 mg / L. Facultative denitrifying bacteria use organic substances such as acetic acid and methanol as electron donors, and NO3 - , NO2 - as electron acceptors, decompose organic substances and convert nitrate nitrogen, generating carbon dioxide, water, nitrogen gas, and synthesizing the microorganisms themselves; the dissolved oxygen in the aerobic tank 19 is 2 - 4 mg / L. Aerobic heterotrophic microorganisms absorb nutrients such as glucose, fructose, acetic acid, ethanol, and oxygen in the water for metabolism, decompose the nutrients to obtain energy, and at the same time use the nutrients to synthesize themselves. In addition, aerobic autotrophic nitrifying bacteria oxidize ammonia nitrogen in the water to nitrate nitrogen under aerobic conditions. An internal circulation is set up to return the wastewater containing nitrate nitrogen at the end of the aerobic tank 19 to the front end of the anoxic tank 18 to complete denitrification and nitrogen removal. The organic substances and nitrogen elements in the wastewater are removed through the A / O tank.

[0036] After the effluent from the A / O tank undergoes sedimentation separation in the secondary sedimentation tank 5, the effluent flows successively into the facultative oxygen tank 6 and the biological contact oxidation tank 7. Among them, the dissolved oxygen in the facultative oxygen tank 6 is less than 1 mg / L, and facultative and anaerobic microorganisms that are easy to attach and grow are screened through combined packing; the oxygen concentration in the biological contact oxidation tank 7 is 2 - 3 mg / L, and the biofilm can be divided into an anaerobic layer / anoxic layer and an aerobic layer from the filter material outwards. Among them, the aerobic layer is located on the outer layer of the biofilm and can directly contact the oxygen in the air or the dissolved oxygen in the sewage aerated by the aeration device, while the anaerobic layer is located on the inner layer of the biofilm. Due to the diffusion limitation of oxygen, the microorganisms in the inner layer are in an anoxic or even anaerobic state. Therefore, anaerobic, facultative, and aerobic microorganisms attach and grow on the packing in sequence, forming a biofilm with a stepwise distribution of oxygen concentration. Under the action of the biofilm, organic matters such as small molecule sugars, formic acid, acetic acid, methanol, and ethanol are adsorbed and degraded, and the nitrification and denitrification processes are completed to further remove nitrogen elements.

[0037] The effluent from the biological contact oxidation tank 7 flows into the tertiary reaction tank 9 after sedimentation in the intermediate sedimentation tank 8. Agents such as PAC and PAM are added to the reaction tank. The addition amount of PAC is 0.35 - 0.45 kg / m 3 wastewater, and the addition amount of the PAM is 0.005 - 0.01 kg / m 3， coagulation reactions occur for SS, organic matters, colloids, etc. in the wastewater sewage, gradually aggregating, increasing in particle size and separating from the water. The effluent enters the final sedimentation tank 10, and the surface load of the sedimentation tank is greatly increased through inclined tubes, inclined plates, and honeycomb packing. The supernatant after sedimentation enters the clear water tank 11.

[0038] During the production wastewater treatment process, part of the sediment sludge in the hydrolysis sedimentation tank 3 is refluxed to the hydrolysis acidification tank 2 to supplement the lost strains, the sediment sludge in the secondary sedimentation tank 5 is refluxed to the front end of the A / O tank to supplement the lost strains, the effluent biofilm and suspended sludge in the intermediate sedimentation tank 8 are refluxed to the facultative oxygen tank 6 after sedimentation to supplement the lost microbial quantity of the system. In addition, part of the sludge from the hydrolysis sedimentation tank 3, the secondary sedimentation tank 5, and the intermediate sedimentation tank 8 enters the biochemical sludge thickening tank 14, and the sludge cakes after dehydration in the biochemical sludge thickening tank 14 and the physical and chemical sludge tank 15 are transported out for treatment.

[0039] Example 1

[0040] It is a 120 m 3 / d hydroxypropyl methylcellulose wastewater treatment device supporting a 500 - ton - per - year hydroxypropyl methylcellulose project of a fine chemical production enterprise. The hydroxypropyl methylcellulose wastewater to be treated is mainly divided into two parts, including high - concentration 10 m 3 / d, including separation and purification wastewater, kettle - washing wastewater, etc., and low - concentration 110 m 3 / d, including steam condensate, workshop cleaning wastewater, product washing wastewater, domestic sewage, initial rainwater, etc., with a total of 120 m 3 / d. The total salt content of high-concentration wastewater is 30,000-35,000 mg / L. After mixing with low-concentration wastewater, the total salt content is within 3000 mg / L. The mixed wastewater is treated and discharged into the local municipal pipe network. See Table 1 for water quality and discharge requirements:

[0041] Table 1

[0042]

[0043] The wastewater removal rate of the wastewater treatment system in this embodiment is shown in Table 2:

[0044] Table 2

[0045]

[0046] It can be seen that the hydroxypropyl methylcellulose production wastewater meets the emission index requirements after being treated by the wastewater treatment system of the utility model. At the same time, the wastewater treatment system of the utility model gives full play to the advantages of each process, improves the treatment efficiency and water quality compliance rate, is environmentally friendly and energy-saving, and avoids the problems of high salinity inhibiting microbial activity and high operating costs caused by the use of high-energy consumption equipment.

[0047] The above-described embodiments are only preferred embodiments for fully illustrating the present utility model, and the protection scope of the present utility model is not limited thereto. Equivalent substitutions or changes made by technicians in the technical field on the basis of the present utility model are all within the protection scope of the present utility model. The protection scope of the present utility model shall be subject to the claims.

Claims

1. A hydroxypropyl methylcellulose production wastewater treatment system, characterized in that: The invention comprises a regulating tank, a hydrolysis acidification tank, a hydrolysis sedimentation tank, a UASB anaerobic reactor, an A / O tank, a secondary sedimentation tank, an anaerobic tank, a biological contact oxidation tank, an intermediate sedimentation tank, a tertiary reaction tank, a final sedimentation tank and a clear water tank which are sequentially connected and arranged, and also comprises a low-concentration wastewater collection tank and a high-concentration wastewater collection tank which are connected to the regulating tank.

2. The hydroxypropyl methylcellulose production wastewater treatment system according to claim 1, characterized in that: It also includes a biochemical sludge thickening tank; The sludge outlet of the hydrolysis sedimentation tank is divided into two routes, one route is connected to the hydrolysis acidification tank, and the other route is connected to the biochemical sludge concentration tank; The sludge outlet of the secondary sedimentation tank is divided into two routes, one route is connected to the A / O tank, and the other route is connected to the biochemical sludge concentration tank; The sludge outlet of the intermediate sedimentation tank is divided into two routes, one route is connected to the aerobic tank, and the other route is connected to the biochemical sludge concentration tank.

3. The hydroxypropyl methylcellulose production wastewater treatment system according to claim 1, characterized in that: It also includes a physicochemical sludge pool, which is connected to the bottom sludge outlet of the final sedimentation tank.

4. The hydroxypropyl methylcellulose production wastewater treatment system according to claim 1, characterized in that: An intermediate water tank is also arranged between the hydrolysis sedimentation tank and the UASB anaerobic reactor.

5. The hydroxypropyl methylcellulose production wastewater treatment system according to claim 1, characterized in that: The A / O pool comprises an anoxic pool and an aerobic pool, the water outlet of the anoxic pool is connected to the water inlet of the aerobic pool, and the bottom of the aerobic pool is connected to the anoxic pool through a nitrification liquid reflux pipe.

6. The hydroxypropyl methylcellulose production wastewater treatment system according to claim 1, characterized in that: A bottle brush-shaped elastic three-dimensional fiber filler is arranged in the hydrolysis acidification tank.

7. The hydroxypropyl methylcellulose production wastewater treatment system according to claim 1, characterized in that: The anoxic tank and the biological contact oxidation tank are filled with a combination of polyethylene discs and synthetic fiber bundles.

8. The hydroxypropyl methylcellulose production wastewater treatment system according to claim 1, characterized in that: The final sedimentation tank is an inclined plate sedimentation tank, in which inclined tubes, inclined plates and honeycomb fillers are arranged.

9. The hydroxypropyl methylcellulose production wastewater treatment system according to claim 1, characterized in that: The secondary sedimentation tank is a radial flow sedimentation tank, and the hydrolysis sedimentation tank and the intermediate sedimentation tank are vertical flow sedimentation tanks.

10. The hydroxypropyl methylcellulose production wastewater treatment system according to claim 5, characterized in that: The aerobic tank and the biological contact oxidation tank are both provided with microporous aeration modules.

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