Maleic anhydride sewage treatment process and sewage treatment system

Abstract

The invention discloses a maleic anhydride sewage treatment process and a sewage treatment system. The maleic anhydride sewage treatment process comprises the following steps: S1, carrying out buffer treatment on maleic anhydride sewage; s2, carrying out demulsification and multi-dimensional electro-catalysis pretreatment on the maleic anhydride sewage treated in the step S1; s3, carrying out anaerobic reaction treatment on the maleic anhydride sewage treated in the step S2; s4, performing neutral catalytic oxidation and aerobic treatment on the maleic anhydride sewage treated in the step S3; s5, performing electro-catalysis treatment on the maleic anhydride sewage treated in the step S4 to obtain sewage meeting the standard; the technical problems that in the prior art, the maleic anhydride sewage is high in pollutant concentration, low in biochemical treatment degradation speed and low in efficiency are effectively solved by removing specific pollutants such as DBP and DOP in the maleic anhydride sewage and adopting a method of demulsification, multi-dimensional electro-catalysis, efficient anaerobic treatment, multi-stage aerobic treatment, catalytic oxidation and electro-catalysis.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, and in particular to a maleic anhydride sewage treatment process and a sewage treatment system. Background Art

[0002] Maleic anhydride is the third largest anhydride in the world after phthalic anhydride and acetic anhydride. It has a wide range of uses. It is mainly used as a raw material for the production of 1,4-butanediol, unsaturated polyester resins and alkyd resins. It is also a comonomer for coatings, maleic rosin and polymaleic anhydride. It can also be used as an organic chemical raw material for the production of ink additives, papermaking additives, plasticizers, and can also be used in medicine and pesticides. At the same time, maleic anhydride is also used in the production of raw materials for glass fiber reinforced plastics, petrochemicals, food processing, medicine and building materials, and has extremely broad development and application prospects.

[0003] However, in the prior art, the maleic anhydride production process is mainly based on solvent absorption, or the maleic anhydride production device is used to produce maleic anhydride. In this process, a large amount of maleic anhydride wastewater will be produced. Wherein the solvent absorption is mainly dibutyl phthalate / diisobutyl hexahydrophthalate (DIBE / DBP), and the solvent after use forms the main component of sewage in the maleic anhydride production process. The solvent after use contains impurities such as acetic acid, acrylic acid, n-butanol, and a small amount of maleic anhydride. Therefore, maleic anhydride wastewater needs to be treated and discharged after reaching the discharge standard. Chemical oxygen demand COD (Chemical Oxygen Demand) is an important indicator of organic pollution in water bodies, which can reflect the pollution degree of water bodies. Maleic anhydride wastewater can only be discharged when it is reduced to below 500mg / L.

[0004] However, the following technical problems remain difficult to solve: 1. Maleic anhydride wastewater has a high concentration of organic matter, with COD as high as 30,000-60,000 mg / L. It is a high-concentration organic wastewater with complex composition and a pH value of 1-2, which is strongly acidic. It contains a large amount of organic acids and benzene ring substances, has a slow biodegradation rate, and is difficult to treat biochemically.

[0005] 2. Maleic anhydride wastewater not only has a high concentration of pollutants, but also contains a large amount of grease. A large amount of oil will block the dissolved oxygen in the air from entering the aerobic tank. The grease will also wrap the microorganisms and cause their death, reducing the biochemical treatment effect; 3. The nutrients in maleic anhydride wastewater are single, the carbon-nitrogen ratio is seriously unbalanced, and some nutrients necessary for microbial production are lacking, so they need to be properly supplemented in the biochemical stage.

[0006] 4. Maleic anhydride wastewater contains characteristic pollutants such as DBP and DOP, and the discharge standard is 0.1 mg / L. The biodegradability is extremely poor and it is very easy to exceed the standard.

[0007] It can be seen that in the prior art, whether it is a biochemical method or a physical and chemical method such as concentration and evaporation to treat maleic anhydride wastewater, the physical and chemical method is cumbersome to operate and has high treatment costs; maleic anhydride wastewater treated by the biochemical method is difficult to meet the chemical oxygen demand COD emission standards.

[0008] Therefore, the current technology related to maleic anhydride wastewater treatment process still needs to be further improved. Summary of the invention

[0009] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a maleic anhydride wastewater treatment process and a wastewater treatment system, which solves the technical problems of high pollutant concentration, slow biochemical degradation rate and low efficiency of maleic anhydride wastewater in the prior art.

[0010] To achieve the above object, the present invention adopts the following technical solution: On the one hand, the present invention provides a maleic anhydride wastewater treatment process, comprising the following steps: S1, buffering the maleic anhydride wastewater; S2, performing demulsification and multi-dimensional electrocatalytic pretreatment on the maleic anhydride wastewater treated in step S1; S3, subjecting the maleic anhydride wastewater treated in step S2 to anaerobic reaction treatment; S4, performing neutral catalytic oxidation and aerobic treatment on the maleic anhydride wastewater treated in step S3; S5. Performing electrocatalytic treatment on the maleic anhydride wastewater treated in step S4 to obtain wastewater meeting the standards after treatment.

[0011] On this basis, further preferably, the demulsification and multi-dimensional electrocatalytic pretreatment of maleic anhydride wastewater in step S2 specifically comprises the following steps: The maleic anhydride wastewater treated in step S1 is subjected to demulsification pretreatment and vortex flotation to remove insoluble matter and grease in the maleic anhydride wastewater; Then multi-dimensional electrocatalytic pretreatment and ion flotation are carried out to remove insoluble matter.

[0012] On this basis, it is further preferred that the demulsification pretreatment is performed using a demulsifier, and the components of the demulsifier include ethers, alcohols, organic acids, surfactants and water.

[0013] On this basis, it is further preferred that the demulsifier comprises the following parts by weight: Ethers 28-32%, alcohols 10-12%, organic acids 5-8%, surfactants 10-12%, and the remainder is water.

[0014] On this basis, further preferably, the anaerobic reaction treatment described in S3 specifically includes the following steps: The maleic anhydride wastewater treated in step S2 is subjected to ABR anaerobic treatment, and then subjected to composite anaerobic treatment at 30-40°C.

[0015] In another aspect, the present invention also provides a sewage treatment system for the maleic anhydride sewage treatment process according to the first aspect, comprising: Buffer unit, used to buffer the maleic anhydride wastewater load to facilitate subsequent treatment; A pretreatment unit, used for pre-treating the maleic anhydride wastewater by demulsification and multi-dimensional electrocatalysis; An anaerobic unit, used for anaerobically treating the maleic anhydride wastewater; A neutral catalytic oxidation and aerobic unit, used for neutral catalytic oxidation and aerobic treatment of the maleic anhydride wastewater; The electrocatalytic unit is used for electrocatalytically treating the maleic anhydride wastewater.

[0016] On this basis, more preferably, the pretreatment unit further comprises a flotation unit, and the flotation unit is used to perform flotation operation on the maleic anhydride wastewater subjected to the demulsification and multi-dimensional electrocatalytic pretreatment.

[0017] On this basis, more preferably, the air flotation unit further includes a vortex air flotation unit and an ion air flotation unit. The vortex flotation unit is used to remove insoluble matter and grease from maleic anhydride wastewater after demulsification pretreatment; The ion flotation unit is used to remove insoluble matter after multi-dimensional electrocatalytic pretreatment.

[0018] On this basis, it is further preferred that the system includes: a buffer tank, a coalescing oil remover, a regulating tank, an acidic demulsification reaction tank, a vortex flotation, a multi-dimensional electrocatalytic reactor, an ion flotation, a first transfer tank, an ABR anaerobic tank, an anaerobic regulating tank, a composite anaerobic reactor, an HCR high-efficiency aerobic tower, a first biochemical sedimentation tank, an intermediate reflux tank, a fixed bed catalytic oxidation tank, an enhanced aerobic tank, a second biochemical sedimentation tank, a second transfer tank, a coagulation reaction tank, a physicochemical sedimentation tank, an electrocatalytic tank and a clear water tank connected in sequence.

[0019] On this basis, it is further preferred that an accident pool is further included, and the accident pool is located between the buffer tank and the coalescing deoiler.

[0020] The maleic anhydride wastewater treatment process of the present invention has the following beneficial effects compared with the prior art: (1) The maleic anhydride wastewater treatment process of the present invention can effectively remove characteristic pollutants such as DBP and DOP in maleic anhydride wastewater, and adopts the method of demulsification + multi-dimensional electrocatalysis + high-efficiency anaerobic + multi-stage aerobic + catalytic oxidation + electrocatalysis, and finally completely degrades the pollutants in the water to ensure that the effluent discharge meets the standards.

[0021] (2) In the conventional process, sodium hydroxide or lime is first added to neutralize this type of sewage, and then polyaluminium chloride or polyacrylamide is used for demulsification. The dosage of the reagents is large, the sludge output is large, and the oil and fat components and other components enter the sludge, resulting in large sludge output and high operating costs. The present invention first uses a coalescing degreaser to separate the tar in the sewage, and the separated tar can be recycled. The demulsification is divided into two steps. The first step is to use a conversion demulsifier to demulsify under acidic conditions, so as to effectively separate the oil substances such as DBP and DOP in the sewage, and the separated lipid components can be processed into raw materials. The second step is to use conventional polyaluminium chloride or polyacrylamide for demulsification, which can reduce the sludge output and reduce the sludge treatment cost, and can also recover part of the raw materials.

[0022] (3) This type of wastewater contains a large amount of benzene ring organic matter with poor biodegradability. The B / C ratio is generally around 0.1, which is difficult to biodegrade. The process of the present invention adopts a combination of multiple advanced oxidations and multiple biochemical treatments to maximize the degradation function of the biochemical system and minimize the operating cost of the advanced oxidation. Compared with a single catalytic + biochemical treatment, the operating cost can be reduced by more than 50%.

[0023] (4) The ABR anaerobic reactor is used as the first phase of the two-phase anaerobic reactor, and an anaerobic microbial production promoter is added to it to maintain the biological activity in the ABR reactor, decomposing the benzene ring organic matter and other difficult-to-degrade organic matter in the sewage into small molecular organic matter to improve the biodegradability, and the B / C of maleic anhydride sewage can be increased to about 0.3. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 The figure is a flow chart of the maleic anhydride wastewater treatment system shown in the present invention. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0027] The present invention proposes a maleic anhydride wastewater treatment process and a wastewater treatment system, which can effectively remove characteristic pollutants such as DBP and DOP in maleic anhydride wastewater, and adopt a method of demulsification + multi-dimensional electrocatalysis + high-efficiency anaerobic + multi-stage aerobic + catalytic oxidation + electrocatalysis, so as to finally completely degrade the pollutants in the water and ensure that the effluent discharge meets the standards.

[0028] Example 1

[0029] This embodiment provides a maleic anhydride wastewater treatment process, which specifically includes the following steps: S1, buffering the maleic anhydride wastewater; S2, performing demulsification and multi-dimensional electrocatalytic pretreatment on the maleic anhydride wastewater treated in step S1; S3, subjecting the maleic anhydride wastewater treated in step S2 to anaerobic reaction treatment; S4, performing neutral catalytic oxidation and aerobic treatment on the maleic anhydride wastewater treated in step S3; S5. Performing electrocatalytic treatment on the maleic anhydride wastewater treated in step S4 to obtain wastewater meeting the standards after treatment.

[0030] In this embodiment, specifically, the demulsification and multi-dimensional electrocatalytic pretreatment of maleic anhydride wastewater in step S2 specifically includes the following steps: The maleic anhydride wastewater treated in step S1 is subjected to demulsification pretreatment and vortex flotation to remove insoluble matter and grease in the maleic anhydride wastewater; Then multi-dimensional electrocatalytic pretreatment and ion flotation are carried out to remove insoluble matter.

[0031] In this embodiment, specifically, the demulsification pretreatment is performed using a demulsifier, and the components of the demulsifier include ethers, alcohols, organic acids, surfactants and water.

[0032] In this embodiment, specifically, the components of the demulsifier include the following parts by weight: Ethers 28-32%, alcohols 10-12%, organic acids 5-8%, surfactants 10-12%, and the remainder is water.

[0033] The demulsifier is a compound of ethers, alcohols, surfactants and ammonia. The weight percentages of these ingredients are 28-32% polyoxyether, 10-12% polymer triols, 5-8% toluene sulfonic acid surfactants and 10-15% small molecule cationic polyamines, and the rest is water.

[0034] In this embodiment, specifically, the anaerobic reaction treatment described in S3 specifically includes the following steps: The maleic anhydride wastewater treated in step S2 is subjected to ABR anaerobic treatment, and then subjected to composite anaerobic treatment at 30-40°C.

[0035] Example 2

[0036] Based on Example 1, this embodiment provides a sewage treatment system for a maleic anhydride sewage treatment process, comprising: Buffer unit, used to buffer the maleic anhydride wastewater load to facilitate subsequent treatment; A pretreatment unit, used for pre-treating the maleic anhydride wastewater by demulsification and multi-dimensional electrocatalysis; An anaerobic unit, used for anaerobically treating the maleic anhydride wastewater; A neutral catalytic oxidation and aerobic unit, used for neutral catalytic oxidation and aerobic treatment of the maleic anhydride wastewater; The electrocatalytic unit is used for electrocatalytically treating the maleic anhydride wastewater.

[0037] In this embodiment, specifically, the pretreatment unit further comprises a flotation unit, and the flotation unit is used to perform flotation operation on the maleic anhydride wastewater subjected to the demulsification and multi-dimensional electrocatalytic pretreatment.

[0038] In this embodiment, specifically, the air flotation unit further includes a vortex air flotation unit and an ion air flotation unit. The vortex flotation unit is used to remove insoluble matter and grease from maleic anhydride wastewater after demulsification pretreatment; The ion flotation unit is used to remove insoluble matter after multi-dimensional electrocatalytic pretreatment.

[0039] Example 3

[0040] A sewage treatment system for a maleic anhydride sewage treatment process, such as Figure 1 The system includes: a buffer tank, a coalescing deoiler, a regulating tank, an acid demulsification reaction tank, a vortex flotation, a multi-dimensional electrocatalytic reactor, an ion flotation, a first transfer tank, an ABR anaerobic tank, an anaerobic regulating tank, a composite anaerobic reactor, an HCR high-efficiency aerobic tower, a first biochemical sedimentation tank, an intermediate reflow tank, a fixed-bed catalytic oxidation tank, an enhanced aerobic tank, a second biochemical sedimentation tank, a second transfer tank, a coagulation reaction tank, a physicochemical sedimentation tank, an electrocatalytic tank and a clear water tank, which are connected in sequence.

[0041] In this embodiment, specifically, the buffer tank, maleic anhydride sewage in the initial stage of treatment due to excessive load, exceeds the design capacity of the existing sewage treatment system, the system collapse occurs. Therefore, a buffer tank is required, the hydraulic retention time of the buffer tank is 3-15d, which can effectively buffer the sewage load and protect the subsequent treatment facilities.

[0042] The tank body is generally cylindrical, made of steel structure, with a top cover and insulation layer, stairs, liquid level gauge, thermometer, lifting pump and other ancillary facilities.

[0043] Online monitoring is performed on the sewage in the buffer tank. The monitoring indicators include pH, conductivity, COD, etc. If the above indicators exceed the safety value: that is, COD < 50000 mg / l, pH > 1.0, conductivity < 50 ms / cm, it is regarded as abnormal sewage. The lifting pump transports the sewage in the buffer tank to the accident pool for storage. In this embodiment, specifically, the accident pool is located between the buffer tank and the coalescing degreasing device; if it is a normal value lower than the safety value, the lifting pump transports the sewage to subsequent facilities for treatment.

[0044] In this embodiment, specifically, the coalescing deoiler, the maleic anhydride wastewater contains tar and lipid substances. The coalescing deoiler can remove the floating oil and dispersed oil in the wastewater as much as possible, and it is possible to recycle some valuable products.

[0045] The coalescing oil remover is made of 304 stainless steel and has a cylindrical structure. It is equipped with a coalescing filter element and a separation filter element. It can automatically drain oil. The filter element accuracy is 0.05μm and the oil removal rate is greater than 99%.

[0046] In this embodiment, specifically, the regulating tank is used to regulate the water quality and water quantity of normal sewage that meets the conditions, so that the sewage flow and water quality are stable and balanced, creating favorable conditions for subsequent treatment facilities.

[0047] The regulating tank is generally cylindrical or square, with a hydraulic retention time of 1-3 days, a steel structure or a reinforced concrete + fiberglass anti-corrosion structure, with a top cover and insulation layer, stairs, liquid level gauge, thermometer, lifting pump and other ancillary facilities.

[0048] In this embodiment, specifically, the acidic demulsification reaction tank is used to pre-treat the maleic anhydride wastewater by demulsification. Because maleic anhydride wastewater contains a large amount of organic acids, such as maleic acid, fumaric acid, phthalic acid, cis-acid, etc., and also contains lipid substances such as DBP and DOP, in general, in order to remove lipid substances in wastewater, in addition to physical oil separation or filtration, chemical demulsification and oil removal are also required, but the use conditions of demulsifiers are generally under pH neutral conditions.

[0049] For this type of sewage, the present invention provides a demulsifier that can be used under acidic conditions, which can effectively remove characteristic pollutants such as DBP and DOP in sewage. Since no components such as PAC and PAM are added, the grease layer formed after demulsification can also be recycled and has certain economic value.

[0050] Demulsifiers are compounded from ethers, alcohols, surfactants, and ammonia, with the weight percentages of these ingredients being 28-32% polyoxyether, 10-12% polymer triols, 5-8% toluene sulfonic acid surfactants, and 10-15% small molecule cationic polyamines, and the rest being water. Demulsification of DOP, DBP, and oil pollutants can be achieved within a pH range of 1-2, with a demulsification effect of 90-95%.

[0051] In this embodiment, specifically, the acid demulsification reaction tank is generally a square water tank with a hydraulic retention time of 2-4 hours, a stainless steel structure or a reinforced concrete + fiberglass anti-corrosion structure, with a top cover and insulation layer, a stirring system, a liquid level meter, a thermometer, a dosing system and other ancillary facilities.

[0052] In this embodiment, specifically, the vortex flotation is a flotation device that does not require a reflux pump, an air compressor, a container tank, or a releaser. The vortex pump cuts the air into fine bubbles that dissolve in the sewage, and then the flocs in the sewage are brought out of the water to form a scum layer through the action of the fine bubbles. This process can remove pollutants such as residual grease, insoluble matter, and suspended matter in the sewage.

[0053] The vortex flotation is a rectangular device with a surface load of 2.0-4.0m 3 / m 2 , generally made of carbon steel lined with glass fiber reinforced plastics or stainless steel, with top cover and insulation layer, stirring system, level gauge, thermometer, dosing system and other ancillary facilities. Vortex flotation can basically remove the suspended solids formed after acid demulsification, and the removal rate of suspended solids reaches 90-95%.

[0054] In this embodiment, specifically, the multidimensional electrocatalytic reactor uses the catalytic action of a high-frequency pulsed DC power supply and a multidimensional particle electrode to oxidize and reduce the difficult-to-degrade components and toxic organic matter in the sewage, thereby improving the biodegradability of the sewage. The B / C ratio of this sewage is generally less than 0.1 before electrocatalysis. After being treated by the multidimensional electrocatalytic device, the B / C ratio can be increased to 0.2-0.3, greatly improving the biodegradability, reducing biological toxicity, and creating favorable conditions for subsequent biochemical treatment of sewage.

[0055] Multidimensional electrocatalysis uses graphite as the positive and negative electrodes, the hydraulic retention time is 1-4h, and the iron-carbon micro-electrolysis filler is used as the particle electrode. The distance between the positive and negative electrodes is 100-200mm, the voltage is 10-30V, and the current is 50-100A / m 2The power supply adopts high-frequency pulse power supply, the pulse frequency is 10-100Hz, and the electrode replacement cycle is 1-100s. The iron-carbon micro-electrolysis filler is spherical with a diameter of 10-20mm. The components are refined iron powder, activated carbon, catalyst, etc., and it operates under pH 3-4. The COD removal rate is 10-30%, which can increase the B / C value in sewage from about 0.1 to 0.3.

[0056] In this embodiment, specifically, ion flotation, after multi-dimensional electrocatalysis, the particle electrode will have a certain loss, and then produce suspended matter, and some organic matter will also generate some insoluble matter due to oxidation-reduction reaction, and the above-mentioned pollutants can be effectively removed by ion flotation. The particle size of microbubbles in ion flotation is nanometer to micrometer, which has higher adsorption than the millimeter-level bubbles of conventional flotation, and the removal efficiency of insoluble matter in sewage is close to 100%.

[0057] Ion flotation is a rectangular device with a surface load of 2.0-4.0m 3 / m 2 , generally made of steel or stainless steel, with top cover and insulation layer, stirring system, level gauge, thermometer, dosing system, air compressor, ion bubble generator, reflux pump, releaser and other ancillary facilities. The pH value of ion flotation operation is 6-7, the dissolved air water reflux ratio is 50-100%, and the air-water ratio of ion flotation is 20-50L / m 3 The pressure of the dissolved air tank is 0.4-0.6MPa, and the diameter of the dissolved air bubbles is 1-100μm.

[0058] In this embodiment, specifically, the first transfer tank collects ion gas floatation water and return water from subsequent treatment units, mixes them in a certain proportion, and then lifts them to the ABR anaerobic tank for treatment.

[0059] The first transfer tank is generally a steel structure or a steel-concrete structure with a hydraulic retention time of 2-8 hours, and is equipped with ancillary facilities such as a top cover and insulation layer, a mixing system, a liquid level gauge, a thermometer, etc.

[0060] In this embodiment, specifically, the ABR anaerobic tank is a baffled reaction tank, which realizes the first and second anaerobic reaction processes and controls them in the hydrolysis and acidification stages. Its main function is to improve the biodegradability of wastewater to facilitate subsequent biological treatment; at the same time, sulfate will be reduced to hydrogen sulfide by sulfate-reducing bacteria during the hydrolysis and acidification process.

[0061] The ABR anaerobic tank is generally a steel-concrete structure with ancillary facilities such as a top cover, baffled water distribution system, filler support, reflux system, sedimentation system, etc. The volumetric load of the ABR anaerobic tank is 1-5kg COD / m 3 .d, sludge concentration is 10-15kg / m 3It is generally divided into 3-6 stages for series operation. The rising flow rate of each stage is 0.2-0.5m / h, and the COD removal rate of ABR anaerobic tank is 10-30%.

[0062] In this embodiment, specifically, the anaerobic regulating tank is used to adjust the water quantity, water quality, flow rate, temperature and alkalinity before the composite anaerobic reactor. The effluent from the ABR anaerobic tank and the effluent from the composite anaerobic reactor are mixed here. Under the action of online instruments such as temperature controller, pH meter, ORP and conductivity, the sewage valve is automatically adjusted to adjust the sewage mixing ratio, so as to automatically adjust the sewage pH value, ORP value and conductivity value to the most suitable conditions for the composite anaerobic reactor. At the same time, the steam valve opening is automatically controlled to regulate the sewage temperature to ensure that the sewage can achieve higher reaction efficiency in the composite anaerobic reactor.

[0063] The anaerobic regulating tank is generally a steel concrete structure with a hydraulic retention time of 0.5-2d, and is equipped with a top cover and stirring system, temperature controller, pH meter, ORP meter, conductivity meter, liquid level meter, steam heating pipe, steam silencer release system, reflux system and other ancillary facilities.

[0064] In this embodiment, specifically, the composite anaerobic reactor is a new type of anaerobic reactor provided by the present invention. The composite anaerobic reactor is based on the standard anaerobic UASB and IC, and a 3m high combined filler is added to the separation zone between the two layers of three-phase separators. The combined filler is a plastic strip structure with an installation spacing of 250mm. During actual operation, wastewater and anaerobic gas-entrained sludge flow upstream through the filler layer. The filler can cut the flocculent sludge mass containing biogas, and the sludge after releasing the biogas returns to the bottom sludge bed area. The filler can also form a film, thereby increasing the sludge amount in the anaerobic reaction tank and improving the treatment efficiency of the reactor.

[0065] The composite anaerobic reactor is generally a stainless steel structure or a steel structure + anti-corrosion layer, with a height of 12-18m, a height-to-diameter ratio of 1.2-2.0, a top cover and an insulation layer, and is equipped with a temperature controller, pH meter, ORP meter, conductivity meter, three-phase separator, water distributor, water seal tank, biogas pressure-stabilizing tank, gas-liquid separator, electrostatic adsorption filler, filler on a bracket, anti-floating system, biogas pipeline, external reflux system, internal reflux system and other ancillary facilities.

[0066] The volume load of the composite anaerobic reactor is 1-3kgCOD / M3.d, and the sludge concentration is 30-60kg / m 3 , the rising flow rate is 0.2-1.0 m / h, the operating temperature is 30-40℃, the operating pH range is 6.8-8.5, the ORP range is -300-600MV, the biogas pressure in the three-phase separator is 1000-3000Pa, and the COD removal rate is 70-90%.

[0067] In this embodiment, specifically, the HCR high-efficiency aerobic tower is a third-generation bioreactor. Since the reactor adopts high-speed jet aeration, it has the characteristics of deep well aeration and fluidized bed. HCR achieves the purpose of high efficiency by increasing the mass transfer rate, with high oxygenation capacity and high sludge activity to meet the requirements of rapid degradation of organic matter in a short time; the reactor has high oxygen transfer efficiency, large volumetric load, and short hydraulic retention time, and is an efficient aerobic biological treatment method. The main feature of the HCR high-efficiency aerobic tower is its large height-to-diameter ratio. Since HCR is a completely mixed reactor, coupled with the synergistic effect of high-concentration sludge, the large fluctuations in water inlet and concentration are fully mitigated, and toxic substances are also diluted, thereby effectively improving the HCR system's ability to resist shock loads.

[0068] In addition to the above advantages, an important reason for choosing the HCR high-efficiency aerobic tower in this system is that it can make full use of the potential energy of the compound anaerobic reactor. The height of the previous compound anaerobic reactor is 12-18m. If ordinary aerobic tanks are used later, the height is generally 4-6m, which wastes the energy consumption of the lifting pump. The HCR reactor is also as high as 12-15m, with a small footprint, and can just take over the water level difference of the compound anaerobic reactor, effectively reducing the consumption of electricity and greatly reducing the footprint of the sewage station.

[0069] HCR high-efficiency aerobic tower is generally made of stainless steel or reinforced concrete, with a height of 12-15m. It is equipped with ancillary facilities such as guide tube, water outlet weir, two-phase nozzle, circulation pump, blower return system, etc. The volume load is 1-5kgCOD / M3.d, and the sludge concentration is 30-60kg / m 3 , the dissolved gas efficiency is 20-50%, and the COD removal rate is 60-80%.

[0070] In this embodiment, specifically, in the first biochemical sedimentation tank, when the effluent from the HCR high-efficiency aerobic tower enters the first biochemical sedimentation tank for mud-water separation, the precipitated aerobic bacteria are returned to the HCR aerobic tank through the sludge pump, and the sewage enters the next treatment process.

[0071] The biochemical sedimentation tank is generally a steel-concrete structure with a height of 4-6m and a surface load of 0.5-1.0m 3 / m 2 It is equipped with ancillary facilities such as water distribution weir, water outlet weir, inclined pipe filler, filler bracket, sludge pump, etc.

[0072] In this embodiment, specifically, the intermediate recirculation tank is used to transport part of the effluent from the first biochemical sedimentation tank to the first transfer tank to mix with the ion flotation effluent to reduce the sewage concentration entering the ABR anaerobic tank.

[0073] The intermediate reflow tank is generally a steel concrete structure with a hydraulic retention time of 2-5h and a height of 4-6m. It is equipped with ancillary facilities such as liquid level meter, lifting pump, electromagnetic flow meter, thermometer, regulating valve, pH meter, etc.

[0074] In this embodiment, specifically, in the fixed bed catalytic oxidation tank, after the sewage is treated at the front end, most of the organic matter has been degraded, but there are still some components with poor biodegradability that are difficult to be decomposed by microorganisms, and chemical treatment is required to change the molecular structure of the difficult-to-degrade components. The fixed bed catalytic oxidation tank is selected here as a kind of neutral catalytic oxidation, which can use a catalyst to catalyze hydrogen peroxide to produce hydroxyl radicals under the condition of pH 7-8, which can not only destroy the molecular structure of residual organic matter in the sewage, but also completely oxidize some of the difficult-to-degrade organic matter.

[0075] Fixed bed catalytic oxidation tanks are generally steel concrete structures with a height of 4-6m, equipped with catalytic fillers, filler support mixing systems, dosing systems and other ancillary facilities. The hydraulic retention time of fixed bed catalytic oxidation tanks is 2-4h, the dosage of hydrogen peroxide (30%) is 50-200% of the COD concentration, and the COD removal rate is 20-40%.

[0076] In the present embodiment, specifically, in the enhanced aerobic tank, after the sewage is catalytically oxidized by the front fixed bed, the biodegradability is further improved, and secondary biodegradation can be carried out, and aerobic bacteria are used to oxidize and remove the organic matter in the sewage again. Since the secondary biochemical residence time is short, some components with a long degradation cycle are difficult to be oxidized and removed. Therefore, the method of adding powdered activated carbon is adopted to first adsorb the difficult-to-degrade organic matter and then slowly degrade it, which can realize the separation of the organic residence time and the hydraulic residence time, and improve the removal effect of the aerobic tank.

[0077] The enhanced aerobic tank is generally a steel-concrete structure with a hydraulic retention time of 12-48 hours and a height of 4-6 meters. It is equipped with ancillary facilities such as an aeration system and a dissolved oxygen meter.

[0078] In this embodiment, specifically, the effluent from the second biochemical sedimentation tank and the activated carbon enhanced aerobic tank enters the second biochemical sedimentation tank for mud-water separation, and the precipitated aerobic bacteria are returned to the activated carbon enhanced aerobic tank through the sludge pump, and the sewage enters the next treatment process.

[0079] The second biochemical sedimentation tank is generally a steel-concrete structure with a surface load of 0.5-1.0m 3 / m 2 , with a height of 4-6m, and is equipped with ancillary facilities such as water distribution weir, water outlet weir, inclined pipe filler, filler bracket, sludge pump, etc.

[0080] In this embodiment, specifically, the second transfer tank collects the effluent from the second biochemical sedimentation tank, mixes it in a certain proportion, and then lifts it to the coagulation reaction tank for treatment.

[0081] The second transfer tank is generally a steel structure or a steel-concrete structure with a hydraulic retention time of 2-8 hours, and is equipped with ancillary facilities such as a top cover and insulation layer, a mixing system, a liquid level gauge, a thermometer, etc.

[0082] In this embodiment, specifically, the coagulation reaction tank removes the residual suspended matter in the sewage by adding coagulants and flocculants into the sewage, thereby improving the effluent water quality and ensuring the clarity of the effluent water.

[0083] The coagulation reaction tank is generally a steel concrete structure with a hydraulic retention time of 0.5-2h and a height of 4-6m. It is equipped with ancillary facilities such as a stirring system, pH meter, and dosing system.

[0084] In this embodiment, specifically, in the physicochemical sedimentation tank, the effluent from the coagulation reaction tank enters the physicochemical sedimentation tank for mud-water separation, and the precipitated sludge is transported to the sludge tank through a sludge pump, and the sewage enters the next treatment process.

[0085] Physicochemical sedimentation tanks are generally steel-concrete structures with a surface load of 0.5-1.0m 3 / m 2 , with a height of 4-6m, and is equipped with ancillary facilities such as water distribution weir, water outlet weir, inclined pipe filler, filler bracket, sludge pump, etc.

[0086] In this embodiment, specifically, the electrocatalytic cell, as the final safeguard, utilizes the catalytic effect of precious metal electrodes to generate a large number of hydroxyl radicals under the action of the electric field, which completely degrades the residual pollutants in the sewage and ensures that the effluent meets the discharge standards.

[0087] The electrocatalytic cell is generally cylindrical or rectangular, with a hydraulic retention time of 0.25-1.0h. The outer shell is made of fiberglass or PP structure, and is equipped with titanium alloy + precious metal coating electrode plates and high-frequency pulse power lamp facilities. The titanium alloy + precious metal coating plate is used as the anode, the titanium alloy plate is used as the cathode, the distance between the positive and negative electrodes is 20-100mm, the voltage is 10-30V, and the current is 30-100A / m 2 The power supply adopts high-frequency pulse power supply, the pulse frequency is 10-100Hz, and the electrode replacement cycle is 1-100s.

[0088] Application Example 1 This example is about a certain enterprise applying the sewage treatment system of Example 3 to treat maleic anhydride sewage, and the results are shown in Table 1.

[0089] Table 1 Effect of sewage treatment system on maleic anhydride sewage

[0090] As can be seen from Table 1, the maleic anhydride wastewater treatment process and treatment system provided by the present invention utilizes the method of demulsification + multi-dimensional electrocatalysis + high-efficiency anaerobic + multi-stage aerobic + catalytic oxidation + electrocatalysis to effectively remove characteristic pollutants such as DBP and DOP in maleic anhydride wastewater, and has achieved good results.

[0091] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A maleic anhydride wastewater treatment process, characterized in that: The following steps are involved: S1, buffering the maleic anhydride wastewater; S2, performing demulsification and multi-dimensional electrocatalytic pretreatment on the maleic anhydride wastewater treated in step S1; S3, subjecting the maleic anhydride wastewater treated in step S2 to anaerobic reaction treatment; S4, performing neutral catalytic oxidation and aerobic treatment on the maleic anhydride wastewater treated in step S3; S5. Performing electrocatalytic treatment on the maleic anhydride wastewater treated in step S4 to obtain wastewater meeting the standards after treatment.

2. The maleic anhydride wastewater treatment process according to claim 1, characterized in that: The demulsification and multi-dimensional electrocatalytic pretreatment of maleic anhydride wastewater in step S2 specifically comprises the following steps: The maleic anhydride wastewater treated in step S1 is subjected to demulsification pretreatment and vortex flotation to remove insoluble matter and grease in the maleic anhydride wastewater; Then multi-dimensional electrocatalytic pretreatment and ion flotation are carried out to remove insoluble matter.

3. The maleic anhydride wastewater treatment process as claimed in claim 2, characterized in that: The demulsification pretreatment is performed by using a demulsifier, and the components of the demulsifier include ethers, alcohols, organic acids, surfactants and water.

4. The maleic anhydride wastewater treatment process as claimed in claim 3, characterized in that: The components of the demulsifier include the following parts by weight: Ethers 28-32%, alcohols 10-12%, organic acids 5-8%, surfactants 10-12%, and the remainder is water.

5. The maleic anhydride wastewater treatment process according to claim 1, characterized in that: The anaerobic reaction treatment described in S3 specifically comprises the following steps: The maleic anhydride wastewater treated in step S2 is subjected to ABR anaerobic treatment, and then subjected to composite anaerobic treatment at 30-40°C.

6. A sewage treatment system using the maleic anhydride sewage treatment process according to any one of claims 1 to 5, characterized in that: include: Buffer unit, used to buffer the maleic anhydride wastewater load to facilitate subsequent treatment; A pretreatment unit, used for pre-treating the maleic anhydride wastewater by demulsification and multi-dimensional electrocatalysis; An anaerobic unit, used for anaerobically treating the maleic anhydride wastewater; A neutral catalytic oxidation and aerobic unit, used for neutral catalytic oxidation and aerobic treatment of the maleic anhydride wastewater; The electrocatalytic unit is used for electrocatalytically treating the maleic anhydride wastewater.

7. The sewage treatment system of the maleic anhydride sewage treatment process according to claim 6, characterized in that: The pretreatment unit further comprises an air flotation unit, and the air flotation unit is used to perform air flotation operation on the maleic anhydride wastewater subjected to the demulsification and multi-dimensional electrocatalytic pretreatment.

8. The sewage treatment system of the maleic anhydride sewage treatment process according to claim 7, characterized in that: The air flotation unit also includes a vortex air flotation unit and an ion air flotation unit. The vortex flotation unit is used to remove insoluble matter and grease from maleic anhydride wastewater after demulsification pretreatment; The ion flotation unit is used to remove insoluble matter after multi-dimensional electrocatalytic pretreatment.

9. The sewage treatment system of the maleic anhydride sewage treatment process according to claim 6, characterized in that: The system comprises: a buffer tank, a coalescing deoiler, a regulating tank, an acid demulsification reaction tank, a vortex flotation, a multi-dimensional electrocatalytic reactor, an ion flotation, a first transfer tank, an ABR anaerobic tank, an anaerobic regulating tank, a composite anaerobic reactor, an HCR high-efficiency aerobic tower, a first biochemical sedimentation tank, an intermediate reflow tank, a fixed-bed catalytic oxidation tank, an enhanced aerobic tank, a second biochemical sedimentation tank, a second transfer tank, a coagulation reaction tank, a physicochemical sedimentation tank, an electrocatalytic tank and a clear water tank, which are connected in sequence.

10. The sewage treatment system of the maleic anhydride sewage treatment process according to claim 9, characterized in that: It also includes an accident pool, which is located between the buffer tank and the coalescing deoiler.

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