A system and process for treating regenerated wastewater in the production of hydrogen peroxide by anthraquinone method

Abstract

The present invention discloses a treatment system and process for regenerated wastewater in the production of hydrogen peroxide by anthraquinone method, comprising a regenerated wastewater storage tank, an air flotation device, a sedimentation tank, a pre-filter device and a coalescence separation device, wherein the regenerated wastewater storage tank is sequentially connected to the air flotation device and the sedimentation tank, and the upper outlet of the sedimentation tank is sequentially connected to the pre-filter device and the coalescence separation device; the bubble making system of the air flotation device is to set an aeration head group at the bottom of the air flotation device, and the front of the aeration head group is connected to compressed air, and the air flotation device is connected to a water pipe. The system is capable of separating aluminum oxide dust from the regenerated wastewater in the production of hydrogen peroxide, reducing the COD of the wastewater, and recovering the working fluid therein. The device is simple to operate and easy to promote and apply, and no flocculant needs to be added during operation to avoid contamination of the working fluid, and can effectively solve the problems of treatment of high COD and high dust content wastewater and recovery of working fluid in the production of hydrogen peroxide.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, in particular to a system and process for treating regenerated wastewater in producing hydrogen peroxide by anthraquinone method. Background Art

[0002] The wastewater generated in the production of hydrogen peroxide by anthraquinone can be divided into three parts: the first is the regeneration wastewater, including the steam condensation wastewater of catalyst regeneration, the condensation wastewater generated by steam purge when replacing alumina in the clay bed, and the steam condensation wastewater of activated carbon regeneration; the second is the wastewater discharged from the system, such as oxidation residual liquid, extraction coalescer drainage and working liquid washing wastewater; the third is the waste alkali liquid withdrawn from the drying tower. The above three types of wastewater all contain working liquid (heavy aromatics, 2-ethylanthraquinone, etc.) components and need to be treated to meet the standards before discharge.

[0003] The generation of regenerated wastewater is characterized by periodicity, intermittence, large single-time generation volume, and containing more working fluid components and dust. The wastewater generated in the current hydrogen peroxide production is treated by the Fenton method, but the existing conventional Fenton method is difficult to achieve the ideal treatment effect, and will cause the sewage station to be overloaded and cause a huge waste of Fenton reagents.

[0004] Patent CN 209652080 U discloses a treatment system for anthraquinone-containing sewage, including an accident pool, a regulating pool, a catalytic oxidation reaction tower, an aerated sedimentation pool, a dissolved air flotation pool, an anaerobic pool, an aerobic MBR pool, a clear water pool, a sewage treatment device, a sludge pool, and a sludge treatment device, which can directly input anthraquinone-containing sewage. The accident pool and regulating pool of the device can ensure that the amount of sewage entering the treatment equipment and the water quality are relatively stable; and a catalytic oxidation reactor is set to degrade macromolecular organic matter to improve the biodegradability of wastewater; after the macromolecular organic matter is degraded, it can enter the anaerobic pool and aerobic MBR pool for further treatment. The device is reliable in operation and can effectively treat the production wastewater of the hydrogen peroxide device, but the treatment process is cumbersome, the operating cost is relatively high, and no effective improvement is made for the regenerated wastewater.

[0005] Patent CN 109534429 A discloses a pretreatment method for wastewater produced by anthraquinone method for hydrogen peroxide. Air is blown into the regenerated wastewater after adjusting the pH to 5-7 and a flocculant is added. The floccules appearing on the upper layer are separated and then added to extract and recover the working solution of heavy aromatics. The COD of the lower aqueous phase can be reduced to below 1500 mg / L, reducing the pressure of later sewage treatment and the consumption of Fenton reagent. However, this method requires the addition of inorganic acid to adjust the pH of the wastewater and the addition of a flocculant to separate the dust in the regenerated wastewater, which may cause contamination of the working solution components in the regenerated wastewater in the subsequent stage, making it difficult to recycle and reuse, further increasing production costs.

[0006] Therefore, it is necessary to establish a recycled wastewater treatment solution to solve the above problems. Summary of the invention

[0007] The first purpose of the present invention is to improve the existing wastewater treatment system for producing hydrogen peroxide by anthraquinone method, and to propose a new type of regeneration wastewater treatment system in view of the deficiencies of the regeneration wastewater treatment system in the existing hydrogen peroxide production process. The system is mainly aimed at regeneration wastewater with high organic components and high dust content, which can effectively make up for the limitations of conventional treatment methods, separate aluminum oxide dust in regeneration wastewater, reduce COD of wastewater, recover working fluid therein, and reduce waste of wastewater treatment agent.

[0008] The second purpose of the present invention is to improve the existing anthraquinone method for producing hydrogen peroxide regeneration wastewater treatment process. The process only needs to add dilution water such as reclaimed water, tap water or pure water, and does not need to add flocculants. It can effectively separate solid particle powders in combination with the improved flotation method, avoid contamination of the working liquid components, facilitate the recovery of the working liquid and return it to the system, and can also fully reduce the difficulty of wastewater treatment. It is worthy of wide promotion and application.

[0009] In order to achieve the above-mentioned purpose of the present invention, the present invention adopts the following technical solutions:

[0010] The first aspect of the present invention provides a treatment system for regenerated wastewater in the production of hydrogen peroxide by an anthraquinone process, comprising a regenerated wastewater storage tank 1, an air flotation device 3, a sedimentation tank 4 / 5, a pre-filter device 8 and a coalescing separation device 9, wherein the regenerated wastewater storage tank 1 is sequentially connected to the air flotation device 3 and the sedimentation tank 4 / 5, and the upper outlet of the sedimentation tank 4 / 5 is sequentially connected to the pre-filter device 8 and the coalescing separation device 9; the bubble making system of the air flotation device 3 is to arrange an aeration head group 15 at the bottom of the air flotation device 3, and the front of the aeration head group 15 is connected to compressed air, and the air flotation device 3 is connected to a water pipe 12.

[0011] Furthermore, the water pipe 12 and the aeration head group 15 are replaced by an air dissolving tank bubble making system.

[0012] The regeneration wastewater is a mixture of one or more of the following: the catalyst regeneration process, the condensate wastewater generated by steam purge during the replacement of aluminum oxide in the clay bed, and the steam condensate wastewater of activated carbon regeneration. The clay bed includes a hydrogenated clay bed and a post-treatment clay bed.

[0013] Furthermore, a stirring device is arranged inside the regenerated wastewater storage tank 1, and the stirring device is used for premixing to prevent the working liquid components contained in the wastewater from stratifying and the dust contained in the wastewater from settling to the bottom, causing blockage of the bottom wastewater outlet; the stirring device is preferably a stirring paddle or a bubbling device, and the bubbling device is preferably a nitrogen bubbling device.

[0014] Furthermore, a sealing cover plate 10 is provided on the top of the regenerated wastewater storage tank 1, and a gas outlet is provided on the cover plate 10. The gas outlet is connected to a recovery device for recovering volatile working liquid solvent components. The recovery device is preferably an adsorption tower or a cooling tower.

[0015] Furthermore, a discharge port is provided at the bottom of the regenerated wastewater storage tank 1 for conveying wastewater. The discharge port is connected to a sewage pump 2. The regenerated wastewater enters the flotation device 3 through the sewage pump 2. The flotation device 3 is preferably located downstream of the sewage pump 2. The design of the regenerated wastewater storage tank 1 can ensure that all components in the wastewater enter subsequent work sections.

[0016] Furthermore, the water pipe is arranged near the regenerated wastewater inlet of the flotation device 3, and is used to add dilution water into the flotation device 3 to dilute the regenerated wastewater mixed by the regenerated wastewater storage tank 1. The dilution water can be selected from reclaimed water, tap water or pure water, and the temperature of the dilution water is 40-60°C.

[0017] Furthermore, the aeration head group 15 is a movable aeration head group, so that it can be lifted, cleaned and replaced; the aeration tank is a system for making bubbles by dissolving a certain amount of air under pressure into water and then directly inputting it into the flotation device 3. The introduction of compressed air and a certain proportion of dilution water can fully destroy the solid-liquid balance of the regenerated wastewater, which is conducive to the separation of working fluid-water-dust particles in the wastewater.

[0018] Furthermore, a sealed top cover 13 is provided on the top of the flotation device 3, and a gas outlet is provided on the top cover 13. The gas outlet is connected to a recovery device, and a large amount of working liquid solvent components enter the recovery device with the air through the outlet of the top cover 13 to recover the solvent. The recovery device is preferably an adsorption tower or a cooling tower.

[0019] Furthermore, a scraper 14 is provided on the upper part of the air flotation device 3, and a collection tank 16 is provided on the side. Some solid dust particles form air flotation bodies and float to the surface of the wastewater. The collection tank 16 is used to collect the working liquid solute and tiny dust particles floating on the liquid surface. The collection tank 16 is emptied regularly. The regenerated wastewater is sent to the sedimentation tank 4 / 5 after being fully diluted and purged with air.

[0020] Furthermore, a baffle 17 is provided at the wastewater inlet of the sedimentation tank 4 / 5, and the baffle 17 can reduce the impact of wastewater input on the wastewater in the tank, and is preferably a vertical baffle; a filler is provided behind the baffle, which is beneficial to accelerate the separation of the solid-liquid two phases, and the filler type is a wire mesh demister mesh pad or a regular filler, which can be selected from one or more of vertical corrugations, meshes, wire meshes, perforated plates, and rolled perforated plate fillers, and the material is stainless steel or polytetrafluoroethylene; a liquid phase outlet is provided at the upper middle part of the side of the sedimentation tank 4 / 5, and the liquid phase outlet is connected to a sewage pump 6 to send it to a pre-filter 8; the bottom of the sedimentation tank 4 / 5 is preferably in an inverted cone shape, and a solid phase outlet is provided at the lowest point, and the solid phase outlet is connected to a sludge pump 7 to go to a plate and frame filter press.

[0021] Furthermore, the sedimentation tanks are two or more sedimentation tanks arranged in parallel, which is convenient for replacement or backwashing during continuous operation of the device.

[0022] Furthermore, the pre-filter device 8 is two or more filters arranged in parallel, which is convenient for replacement or backwashing during continuous operation of the device; the filter is equipped with a filter element, which is preferably a composite of one or more materials such as a polypropylene filter element, a polytetrafluoroethylene filter element, a polyester filter element, a glass fiber filter element, a metal sintered filter element, etc.; the filter further preferably has a backwashing function.

[0023] Furthermore, the filtering accuracy of the pre-filter device 8 is preferably 0.5-30 μm, which is used to intercept a small amount of solid particles brought in and protect the normal operation of the coalescing filter element in the subsequent process coalescing device 9. The liquid wastewater filtered by the pre-filter device 8 goes to the coalescing separation device 9.

[0024] Furthermore, an oil-water separation filter element is provided in the coalescence separation device 9. The oil-water separation filter element is made of polytetrafluoroethylene, polyester or a composite material and is used to separate the working fluid component in the wastewater without solid particles.

[0025] Furthermore, a liquid collecting bag 18 is arranged at the top downstream of the coalescing and separating device 9 for collecting a small amount of working liquid components, a glass sight glass is arranged on the side of the liquid collecting bag 18 for monitoring the oil-water two-phase interface, a working liquid outlet 19 is arranged at the top of the liquid collecting bag 18, and a pipeline is arranged at the working liquid outlet 19 to connect the preparation kettle for recovering the working liquid, and a water phase outlet 20 is arranged at the bottom downstream of the coalescing and separating device 9 to go to a wastewater station, which can be directly discharged or reused after being tested and qualified at the wastewater station, or directly discharged or reused after being further treated and tested and qualified at the wastewater station.

[0026] The second aspect of the present invention provides a process for treating regeneration wastewater in the production of hydrogen peroxide by anthraquinone method, comprising the following steps:

[0027] 1) The regenerated wastewater enters the flotation device 3 from the regenerated wastewater storage tank 1,

[0028] 2) When the bubble making system of the air flotation device 3 is the aeration head group 15, dilution water is added to the air flotation device 3 through the water pipe 12; when the bubble making system of the air flotation device 2 is the dissolved air tank, dilution water is added to the dissolved air tank;

[0029] The volume ratio of the dilution water to the regenerated wastewater is 0.2-2;

[0030] 3) Turn on the bubble making system for aeration, and discharge the regenerated wastewater after sufficient air blowing into the sedimentation tank 4 / 5 and let it stand for 2~24 hours;

[0031] 4) The supernatant from sedimentation tank 4 / 5 passes through pre-filter 8 and enters coalescing separation device 9;

[0032] 5) The working liquid and the aqueous phase are separated by the coalescence separation device 9.

[0033] Furthermore, the temperature of the dilution water is 40-60° C., and reclaimed water, tap water or pure water can be selected as the dilution water according to the dust content and working fluid content in the regenerated wastewater.

[0034] Compared with the existing hydrogen peroxide production wastewater treatment process, the treatment system and process of the regeneration wastewater in the anthraquinone process of the present invention have the following advantages:

[0035] 1. It promotes the formation of flocculent suspended solids and then precipitation of ultrafine powders (diameter < 1 μm) in regeneration wastewater with high solid content and COD. When a pre-filter element with lower filtration accuracy is selected, the powder contained in the wastewater can be effectively removed, reducing the replacement cost of the pre-filter element, and improving the working efficiency and service life of the coalescing filter element. The suspended solids content in the wastewater treated by the pre-filter can be reduced to below 20 mg / L.

[0036] 2. No other ingredients such as flocculants are added to avoid secondary contamination of the working fluid. The working fluid can be recycled after separation and cleaning by the coalescing filter element, which can fully reduce the consumption of the working fluid and Fenton oxidation agent in the existing process and reduce the operating cost of the device.

[0037] 3. This system and process can be used as a supplement to existing sewage treatment plants to relieve the pressure on sewage treatment plants, and the treated reclaimed water can be used to treat recycled wastewater, further reducing the cost of sewage treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a treatment system for regeneration wastewater in the production of hydrogen peroxide using the anthraquinone process.

[0039] Figure 2 This is a treatment process for regeneration wastewater in the production of hydrogen peroxide by the anthraquinone method.

[0040] Among them, 1 is a regenerated wastewater storage tank, 2 is a sewage pump, 3 is an air flotation device, 4 / 5 are sedimentation tanks, 6 is a sewage pump, 7 is a sludge pump, 8 is a pre-filter device, 9 is a coalescence and separation device, 10 is a cover plate, 11 is a compressed air pipe, 12 is a water pipe, 13 is a top cover, 14 is a scraper, 15 is an aeration head group, 16 is an aggregate trough, 17 is a baffle, 18 is a liquid collection bag, 19 is a working fluid outlet, 20 is a sewage outlet, and 21 is a sludge outlet. DETAILED DESCRIPTION

[0041] The present invention will be further described below through specific embodiments in conjunction with the accompanying drawings. The following embodiments are only illustrative and cannot be used to limit the protection scope of the present invention.

[0042] Example 1

[0043] like Figure 1 As shown, a treatment system for regenerated wastewater in the production of hydrogen peroxide by anthraquinone method includes a regenerated wastewater storage tank 1, a sewage pump 2, an air flotation device 3, a sedimentation tank 4 / 5, a sewage pump 6, a sludge pump 7, a pre-filter device 8 and a coalescence separation device 9. The regenerated wastewater storage tank 1 is connected to the sewage pump 2, the air flotation device 3, and the sedimentation tank 4 / 5 in sequence, the upper outlet of the sedimentation tank 4 / 5 is connected to the pre-filter device 8 and the coalescence separation device 9, and the bottom outlet is connected to the sludge pump 7 to go to the plate and frame filter press.

[0044] The regenerated wastewater storage tank 1 is provided with a stirring paddle inside, and a sealing cover plate 10 is provided on the top, and a gas outlet is provided on the cover plate 10, and the gas outlet is connected to the adsorption tower; a dilution water inlet is provided near the regenerated wastewater inlet of the flotation device 3, a sealing top cover 13 is provided on the top of the flotation device 3, and a gas outlet is provided on the top cover 13, and the gas outlet is connected to the adsorption tower, a movable aeration head group is provided at the bottom of the flotation device 3, and compressed air is connected in front of the aeration head group, a scraper 14 is provided on the top of the flotation device 3, and an aggregate trough 16 is provided on the side.

[0045] The sedimentation tank 4 / 5 is two sedimentation tanks arranged in parallel, a vertical baffle is arranged at the wastewater inlet of the sedimentation tank 4 / 5, a filler is arranged behind the baffle, a liquid phase outlet is arranged at the upper middle part of the side of the sedimentation tank, and the liquid phase outlet is connected to a sewage pump 6 to enter the pre-filter 8; the bottom of the sedimentation tank 4 / 5 is an inverted cone, and a solid phase outlet is arranged at the lowest point, and the solid phase outlet is connected to a sludge pump 7 to go to a plate and frame filter press;

[0046] The pre-filter device 8 is two filters connected in parallel, and the filtering accuracy is 0.5-30 μm.

[0047] A liquid collecting bag 18 is arranged at the top downstream of the coalescing and separating device 9, a glass sight mirror is arranged on the side of the liquid collecting bag 18, a working liquid outlet 19 is arranged at the top of the liquid collecting bag 18, a pipeline is arranged at the working liquid outlet 19 to connect to a ton barrel or a preparation kettle, and a water phase outlet 20 is arranged at the bottom downstream of the coalescing and separating device 9. The water phase outlet 20 is arranged at the bottom downstream of the coalescing and separating device to a wastewater station, and is directly discharged or reused after being tested qualified at the wastewater station, or is directly discharged or reused after being further treated and tested qualified at the wastewater station.

[0048] use Figure 1 The process of treating the regeneration wastewater in the production of hydrogen peroxide by anthraquinone method comprises the following steps:

[0049] 1) After the regenerated wastewater enters the regenerated wastewater storage tank 1 through the pipeline, the stirring paddle is turned on to stir for 0.1~2 hours, preferably 0.3~1.2 hours; after sufficient stirring, it enters the flotation device 3 through the sewage pump 2;

[0050] 2) Add reclaimed water at a ratio of V reclaimed water / V reclaimed wastewater = 0.2~2 to fully dilute the reclaimed wastewater. The reclaimed water temperature is 40~60℃;

[0051] 3) Start compressed air with an air pressure of 0.3-0.6 MPa, preferably 0.2-0.5 MPa, and introduce a large number of microbubbles generated by the aeration head group 15 into the diluted regenerated wastewater. The aeration time is 0.1-0.5 h, preferably 0.25-0.4 h. At the same time, start the scraper 14 to collect the working liquid solute and tiny dust particles floating on the liquid surface into the aggregate tank 16, and the aggregate tank 16 is emptied regularly; the regenerated wastewater after being fully purged by air is discharged into the sedimentation tank 4 / 5;

[0052] 4) The regenerated wastewater is continuously or intermittently fed through the sedimentation tank 4 / 5. After the wastewater is discharged from the side inlet, it is left to stand for 2 to 24 hours, preferably 10 to 24 hours. The supernatant enters the coalescence separation device 9 after passing through the sewage pump 6 and the pre-filter 8. The solid particles in the lower layer are sent to the plate and frame filter press through the sludge pump 7;

[0053] 5) After the supernatant of the regenerated wastewater enters the coagulation and separation device 9, the working liquid outlet 19 is opened when the oil-water two-phase interface is located at 30%-80% of the scale on the sight glass of the liquid collecting bag 18, and preferably, the working liquid outlet 19 is opened when the oil-water two-phase interface is located at 50%-70% of the scale on the sight glass of the liquid collecting bag 18. The working liquid outlet 19 is connected to a ton barrel or a preparation kettle to recover the working liquid. A water phase outlet 20 is set at the downstream bottom of the coagulation and separation device 9 to go to the wastewater station, and it is directly discharged or reused after being tested and qualified at the wastewater station, or it is directly discharged or reused after being further treated and tested and qualified at the wastewater station.

[0054] Examples 2-4 are processed using the system and process of Example 1.

[0055] Example 2

[0056] The regenerated wastewater (COD: 12500 mg / L, particle concentration 950 mg / L) enters the regenerated wastewater storage tank through the pipeline and is fully stirred for 0.3 h before entering the flotation device. 中水 / V 再生废水 =2:1 ratio of 40 ℃ recycled water was added, compressed air was turned on, the air pressure was 0.3 MPa, the aeration time was 0.3 h, and the scraper was turned on at the same time. After the aeration, the wastewater was discharged into the sedimentation tank. After standing for 12 h and stratification, the lower layer of solid particles was sent to the plate and frame filter press through the sludge pump, and the supernatant entered the coalescence separation device after the sewage pump and the pre-filter. The oil phase outlet of the coalescence separation device was the working fluid, the water phase COD was 528 mg / L, and the particle concentration was 7 mg / L.

[0057] Example 3

[0058] The regenerated wastewater (COD: 15710 mg / L, particle concentration 1350 mg / L) enters the regenerated wastewater storage tank through the pipeline and is fully stirred for 0.1 h before entering the flotation device. 自来水 / V 再生废水 =1:1 ratio of 50℃ tap water was added, compressed air was turned on, the air pressure was 0.4 MPa, the aeration time was 0.3 h, and the scraper was turned on at the same time. After the aeration, the wastewater was discharged into the sedimentation tank. After standing for 18 hours and stratification, the lower layer of solid particles was sent to the plate and frame filter press through the sludge pump, and the supernatant entered the coalescence separation device after the sewage pump and the pre-filter. The oil phase outlet of the coalescence separation device was the working fluid, the water phase COD was 632 mg / L, and the particle concentration was 13 mg / L.

[0059] Example 4

[0060] The regenerated wastewater (COD: 8420 mg / L, particle concentration 770 mg / L) enters the regenerated wastewater storage tank through the pipeline and is fully stirred for 2 hours before entering the flotation device. 纯水 / V 再生废水 =0.2:1 ratio of 60 ℃ pure water was added, compressed air was turned on, the air pressure was 0.6 MPa, the aeration time was 0.5 h, and the scraper was turned on at the same time. After the aeration, the wastewater was discharged into the sedimentation tank. After standing for 24 hours and stratification, the lower layer of solid particles was sent to the plate and frame filter press through the sludge pump, and the supernatant entered the coalescence separation device after the sewage pump and the pre-filter. The oil phase outlet of the coalescence separation device was the working fluid, the water phase COD was 425 mg / L, and the particle concentration was 5 mg / L.

Claims

1. A process for treating regenerated wastewater using a treatment system for regenerated wastewater in the production of hydrogen peroxide by anthraquinone method, comprising the following steps: 1) The regenerated wastewater enters the flotation device (3) from the regenerated wastewater storage tank (1). 2) adding dilution water to the flotation device (3) through the water pipe (12); The volume ratio of the dilution water to the regenerated wastewater is 0.2-2; 3) Turn on the bubble making system for aeration, and discharge the regenerated wastewater after sufficient air purge into the sedimentation tank (4, 5) and let it stand for 2 to 24 hours; 4) The supernatant from the sedimentation tank passes through the pre-filter (8) and enters the coalescence separation device (9); 5) Separating the working liquid and the water phase by a coalescence separation device (9); The treatment system for regenerated wastewater in the production of hydrogen peroxide by anthraquinone method comprises a regenerated wastewater storage tank (1), an air flotation device (3), a sedimentation tank (4, 5), a pre-filtering device (8) and a coalescence separation device (9), wherein the regenerated wastewater storage tank (1) is connected to the air flotation device (3) and the sedimentation tank (4, 5) in sequence, and the upper outlets of the sedimentation tanks (4, 5) are connected to the pre-filtering device (8) and the coalescence separation device (9) in sequence; The bubble making system of the air flotation device (3) is provided with an aeration head group (15) at the bottom of the air flotation device (3), compressed air is connected in front of the aeration head group (15), and the air flotation device (3) is connected to a water pipe (12); A vertical baffle (17) is provided at the wastewater inlet of the sedimentation tank (4, 5), and a filler is provided behind the baffle; An oil-water separation filter element is provided in the coalescence separation device (9); The dilution water is reclaimed water, tap water or pure water.

2. The process according to claim 1, It is characterized in that A stirring device is arranged inside the regenerated wastewater storage tank (1); a sealing cover plate (10) is arranged on the top of the regenerated wastewater storage tank, and a gas outlet is arranged on the cover plate (10).

3. The process according to claim 2, It is characterized in that The stirring device is a stirring paddle or a bubbling device.

4. The process according to claim 1 or 2, It is characterized in that The aeration head group (15) is a movable aeration head group.

5. The process according to claim 1 or 2, It is characterized in that A sealed top cover (13) is arranged on the top of the air flotation device (3), and a gas outlet is arranged on the top cover (13); a scraper (14) is arranged on the top of the air flotation device (3), and a material collecting trough (16) is arranged on the side.

6. The process according to claim 1 or 2, It is characterized in that The filler is a wire mesh demister pad or a structured filler; the sedimentation tank is two or more sedimentation tanks arranged in parallel.

7. The process according to claim 1 or 2, It is characterized in that The pre-filter device (8) is composed of two or more filters arranged in parallel.

8. The process according to claim 7, wherein the filter is equipped with a polypropylene filter element, a polytetrafluoroethylene filter element, a polyester filter element, a glass fiber filter element, or a metal sintered filter element, or a composite of two or more thereof.

9. According to the process of claim 7, the filter is a filter with a backwashing function; the filtering accuracy of the pre-filter device (8) is 0.5~30 μm.

10. The process according to claim 1 or 2, It is characterized in that The oil-water separation filter element is made of polytetrafluoroethylene, polyester or a composite material; a liquid collecting bag (18) is arranged at the top downstream of the coalescence separation device (9).

11. The process according to claim 10, wherein a glass sight glass is provided on the side of the liquid collecting bag (18).

12. The process according to claim 1 or 2, It is characterized in that The temperature of the dilution water is 40-60°C.

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