Edible oil production wastewater treatment system and process

Abstract

A edible oil production wastewater treatment process comprises the following steps: S1, based on 100% weight of edible oil production wastewater, adding 0.1-0.4% of a treatment agent; the treatment agent includes rice husk ash and quicklime; S2, the edible oil production wastewater with the added treatment agent is fully mixed and floated with the added treatment agent through a mixed flotation tank, demulsification, flocculation, and phosphorus removal; S3, the edible oil production wastewater fully mixed with the added treatment agent is passed through a stepped filter bag to filter out solids and adsorb part of the grease; S4, the filtered edible oil production wastewater is passed through an oil collector to remove grease; S5, further solid-liquid separation and water-oil separation are performed through a static tank. The present invention also provides an edible oil production wastewater treatment system. The present invention does not need to add chemical agents, the treated wastewater has low phosphorus and oil content, and the solid sediment output is small, so it can be directly used as a raw material for biofertilizer, with low cost and short processing time.

Description

Technical Field

[0001] The invention relates to wastewater treatment in edible oil production enterprises, and in particular to an edible oil production wastewater treatment system and process. Background Art

[0002] like Figure 1 The wastewater treatment process of the edible oil production enterprise shown in the figure is a combination of physical and biochemical treatment. The wastewater is treated by adjusting the pH value, oil separation, neutralization, flotation, anaerobic and aerobic treatment. The following problems exist in the process:

[0003] 1. The current process is an intermittent treatment method, which takes a long time to process and requires the construction of multiple large-capacity sewage mixed flotation tanks, regulating tanks and other infrastructure, which occupies a large area and has high investment;

[0004] 2. The main auxiliary materials for sewage treatment include acid, lime, demulsifier, flocculant and other chemical agents, which are not green and environmentally friendly;

[0005] 3. The sludge output is large. A large amount of sludge is produced while treating sewage. As a general solid waste, sludge is prone to secondary pollution if it is not properly handled;

[0006] 4. The current process is a centralized mixed treatment process for all sewage, which ignores the advantages of differentiated classification management and does not consider the combination with previous processes, resulting in energy waste and increased disposal costs. Summary of the invention

[0007] In view of the shortcomings of the prior art, the purpose of the present invention is to provide an edible oil production wastewater treatment process that effectively combines the wastewater indicators of the previous process and implements classified treatment, that is, different process formulas and addition ratios are used for different water quality conditions to achieve one-time treatment to meet the emission standards.

[0008] Compared with traditional processes, each sewage generating unit can be treated separately, avoiding the situation where the overall water quality deteriorates after the sewage from each monomer is mixed, which leads to increased difficulty in treatment and operating costs. The entire process does not require the addition of chemical agents such as acid, demulsifier, flocculant, etc., and the small amount of solid sediment can be directly used as the raw material of biological fertilizer.

[0009] Provided is an edible oil production wastewater treatment system with simple structure, convenient operation, small footprint, capable of realizing continuous industrial operation, short wastewater treatment time, and effective solid-liquid separation and water-oil separation of edible oil production wastewater.

[0010] To achieve the above object, the present invention provides the following technical solutions:

[0011] Provided is an edible oil production wastewater treatment system, comprising a ash adding device, a mixed air flotation tank, a stepped filter bag, an oil collector, and a static tank, wherein the ash adding device is arranged on the sewage inlet of the mixed air flotation tank, the outlet of the mixed air flotation tank is connected to the inlet of the stepped filter bag, the outlet of the stepped filter bag is connected to the inlet of the oil collector, and the outlet of the oil collector is connected to the inlet of the static tank.

[0012] Preferably, the mixed air flotation tank includes an upper baffle and a lower baffle; the lower baffle is fixed to the bottom of the mixed air flotation tank, fits the front and rear walls of the mixed air flotation tank, and leaves a gap with the top; the upper baffle is fixed to the top of the mixed air flotation tank, fits the front and rear walls of the mixed air flotation tank, and leaves a gap with the bottom; the lower baffle is located on the left side of the upper baffle, and the upper baffle and the lower baffle are used in combination to divide the mixed air flotation tank into multiple chambers; the bottom plate is provided with an air flotation plate, and a plurality of small holes are distributed on the air flotation plate and connected to compressed air; the sewage inlet is located on the left side wall of the mixed air flotation tank, and a ash adding device is provided on the sewage inlet, and the sewage outlet is located on the upper right side of the mixed air flotation tank.

[0013] Preferably, the stepped filter bag includes a main body, multiple filter bags, and a water receiving plate. The filter bags are fitted together and the height gradually decreases. They are arranged in a stepped manner along the right side wall to the left outlet and are fixed to the front and rear side walls of the main body. A water receiving plate is fixed on the main body and is located below the filter bag. There is a gap between the water receiving plate and the filter bag. The water receiving plate connects the right side wall to the left outlet. The filter bag is made of a screen structure made of an oleophilic material.

[0014] Preferably, the surface of the multilayer plate of the oil collector is made of oleophilic material, and the multilayer plates are fixed to the left and right side walls of the oil collector at intervals to separate the oil collector to form a bow-shaped space, which leads to the sewage inlet at the top and the sewage outlet at the bottom.

[0015] Preferably, the lipophilic material is specifically a meltblown cloth material.

[0016] Preferably, the static pool includes a partition, which is arranged on the top of the static pool, fits the front and rear walls of the static pool, leaves a gap with the bottom, and separates the static pool to form left and right chambers, the water inlet is located at the top of the right chamber, and the water outlet is located at the upper part of the left side wall of the left chamber, and the bottom of the static pool is paved with rice husk ash and quicklime.

[0017] Preferably, the partition is slidably connected to the top of the static pool and is provided with a sealing strip.

[0018] A process for treating wastewater from edible oil production is also provided, comprising the following steps:

[0019] S1 transports the edible oil production wastewater to a mixed air flotation tank, and adds 0.1-0.4% of a treatment agent based on 100% by weight of the edible oil production wastewater; the treatment agent includes rice husk ash and quicklime;

[0020] S2 passes the edible oil production wastewater with the added treatment agent in S1 through a mixed flotation tank to fully mix and float with the added treatment agent, demulsify, flocculate, and remove phosphorus;

[0021] S3 fully mixes the edible oil wastewater in S2 with the added treatment agent and floats it through a stepped filter bag to filter out solids and absorb part of the grease;

[0022] S4 removes grease from the edible oil production wastewater filtered in S3 through an oil collector;

[0023] S5 further separates the solid-liquid and water-oil separation of the edible oil production wastewater after the oil is adsorbed in S4 through a static tank, and separates the oil pollution to one side through a partition. The water in the lower layer is drained separately to the upper outlet for discharge, and the resulting wastewater meets the discharge standards.

[0024] Preferably, the ratio of rice husk ash to quicklime is selected in different proportions according to the phosphorus content and oil content of the edible oil production wastewater:

[0025] a When phosphorus content is higher than 100ppm, oil content is higher than 2000ppm, and COD is greater than 20000ppm, the addition ratio of rice husk ash to quicklime is 3:1;

[0026] b. When the phosphorus content is 50-100ppm, the oil content is less than 2000ppm, and the COD is 10000-20000ppm, the addition ratio of rice husk ash to quicklime is (2-3): (0.6-0.8);

[0027] c When the phosphorus content is less than 50ppm, there is a little or no oil, and the COD is less than 10000ppm, the addition ratio of rice husk ash to quicklime is within 1:0.4.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The edible oil production wastewater is treated by adding rice husk ash and quicklime in a reasonable ratio. After mixed flotation, filtration, oil collector adsorption and standing, the whole process does not require the addition of chemical agents such as acid, demulsifier and flocculant; the solid precipitate output is small and can be used as a raw material for biological fertilizer; the treated wastewater meets the discharge requirements and can be directly discharged; compared with the traditional process, the process of the present invention has low cost and short treatment time.

[0030] 2. By adding rice husk ash and quicklime in different proportions according to the phosphorus content and oil content of edible oil production wastewater, each unit producing wastewater can be treated separately, avoiding the overall deterioration of the overall water quality after the wastewater of each monomer is mixed, and avoiding increasing the difficulty of treatment and operating costs.

[0031] 3. The sewage with rice husk ash and quicklime is fully mixed in the mixed flotation tank to achieve the effects of demulsification, flocculation and phosphorus removal; by setting the upper and lower baffles with small intervals, diversion can be achieved and the mixed liquid can be fully mixed.

[0032] The stepped filter bags made of lipophilic materials are used to filter and separate solids and liquids layer by layer, filtering out solid sediments while absorbing most of the grease. Because the filter bags have a small mesh size, they can be left standing while filtering. When the water flow reaches the opening of the filter bag, it begins to overflow to the next filter bag. The sewage filtered out of the filter bag is guided by the water receiving plate and flows out from the outlet.

[0033] The internal structure of the oil collector made of lipophilic materials is a bow-shaped design. It uses the principles of wetting and agglomeration, collision and agglomeration, and shallow pools. Through wetting, adsorption, collision, aggregation and removal, it can achieve the effect of two-phase separation and adsorption of grease in a short time.

[0034] The partition of the static pool is used to separate the static pool into left and right chambers. After passing through the stepped filter bag, the sewage is first drained to the right chamber. The sewage further reacts with quicklime / rice husk ash. After standing, the oil is settled on the upper layer and the solid sediment is settled on the bottom layer. At this time, the partition is lifted upward, and the sewage in the lower layer is drained from the bottom to the left chamber and then discharged from the upper outlet, successfully separating the oil and solid sediment. By setting a partition that can slide up and down and adjusting the height of the partition according to the water level to draw water from the lower layer, the grease layer in the right chamber can be effectively isolated. After standing, the solid sediment is settled at the bottom, and the sewage is discharged from the upper outlet of the left chamber.

[0035] 4. Compared with traditional processes, there is no need to build multiple large-capacity sewage mixing flotation tanks, regulating tanks and other infrastructure. It occupies a small area, has a simple structure, is easy to operate, has a short process flow, can achieve continuous industrial operation, has low investment costs, and treats the sewage of each unit separately, thus avoiding the difficulty of treatment caused by mixing various sewage in large quantities. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The current sewage treatment adopts a combination of physical, chemical and biochemical methods;

[0037] Figure 2 The sewage treatment process flow chart of the present invention;

[0038] Figure 3 The general assembly diagram of the sewage treatment system of the present invention;

[0039] Figure 4 A cross-sectional schematic diagram of a mixed air flotation tank;

[0040] Figure 5 Schematic diagram of the cross-section of a stepped filter bag;

[0041] Figure 6 Schematic diagram of oil collector cross section;

[0042] Figure 7 Schematic diagram of a cutaway view of a static pool.

[0043] Explanation of the reference numerals: 1 mixed flotation tank, 2 stepped filter bag, 3 oil collector, 4 static tank, 1-1 lower partition, 1-2 upper partition, 1-3 flotation plate, 2-1 main body, 2-2 filter bag, 2-3 water receiving plate, 2-4 right side wall, 1-4 ash adding equipment, 4-1 partition, 4-2 water inlet, 4-3 water outlet, 4-4 right chamber, 4-5 left chamber. DETAILED DESCRIPTION

[0044] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0045] Traditional crafts such as Figure 1 As shown, the present invention provides the following technical solutions:

[0046] A edible oil production wastewater treatment system comprises a ash adding device, a mixed air flotation tank 1, a stepped filter bag 2, an oil collector 3, and a static tank 4. The ash adding device is arranged on the sewage inlet of the mixed air flotation tank 1, the outlet of the mixed air flotation tank 1 is connected to the inlet of the stepped filter bag 2 through a pipeline, the outlet of the stepped filter bag 2 is connected to the inlet of the oil collector 3 through a pipeline, and the outlet of the oil collector 3 is connected to the inlet of the static tank 4 through a pipeline.

[0047] like Figure 4 As shown, the mixed air flotation tank 1 includes an upper baffle 1-2 and a lower baffle 1-1; the lower baffle 1-1 is fixed to the bottom of the mixed air flotation tank 1, fits the front and rear walls of the mixed air flotation tank 1, and leaves a gap with the top; the upper baffle 1-2 is fixed to the top of the mixed air flotation tank 1, fits the front and rear walls of the mixed air flotation tank 1, and leaves a gap with the bottom; the lower baffle 1-1 is located on the left side of the upper baffle 1-2, and the upper baffle 1-2 and the lower baffle 1-1 are used in conjunction to divide the mixed air flotation tank 1 into multiple chambers; the bottom plate is provided with an air flotation plate 1-3, and a plurality of small holes are distributed on the air flotation plate 1-3 and connected with compressed air; the sewage inlet is located on the left side wall of the mixed air flotation tank 1, and a ash adding device 1-4 is provided on the sewage inlet, and the sewage outlet is located on the upper right side of the mixed air flotation tank 1.

[0048] like Figure 5As shown, the stepped filter bag 2 includes a main body 2-1, a plurality of filter bags 2-2, and a water receiving plate 2-3. The filter bags 2-2 are attached to each other with gradually decreasing height and are arranged in a stepped manner along the right side wall 2-4 to the left outlet, and are fixed to the front and rear side walls of the main body 2-1. A water receiving plate 2-3 is fixed on the main body 2-1 below the filter bags 2-2, and there is a gap between the water receiving plate 2-3 and the filter bags 2-2. The water receiving plate 2-3 is connected to the right side wall 2-4 to the left outlet. The material of the filter bags 2-2 is a screen structure made of a lipophilic group material. The material of the stepped filter bag 2 is a meltblown fabric material. Each filter bag can be installed and disassembled by bolts, or the filter bag can be clamped by a card slot provided on the main body, and can be replaced when necessary.

[0049] As Figure 6 shown, the surface of the multi-layer board of the oil collector 3 is made of a lipophilic group material. The multi-layer boards are fixedly arranged at intervals on the left and right side walls of the oil collector 3, separating the oil collector 3 to form an arcuate space, and this arcuate space leads to the sewage inlet at the top and the sewage outlet at the bottom.

[0050] As Figure 7 shown, the settling tank 4 includes a partition board. The partition board 4-1 is arranged at the top of the settling tank 4, fits the front and rear walls of the settling tank 4, has a gap with the bottom, and separates the left and right of the settling tank 4 to form left and right chambers. The water inlet 4-2 is located at the top of the right chamber 4-4, and the water outlet 4-3 is located at the upper part of the left side wall of the left chamber 4-5. The bottom of the settling tank 4 is paved with rice husk ash and quicklime. The partition board 4-1 is slidably connected to the top of the settling tank 4 and is provided with a sealing strip, and can move up and down to isolate the grease layer in the right chamber.

[0051] As Figure 2 、 Figure 3 shown, using the above-mentioned sewage treatment system for edible oil production, a sewage treatment process for edible oil production is provided, including the following steps:

[0052] S1 Transport the sewage from edible oil production to the mixed gas flotation tank 1, and based on 100% by weight of the sewage from edible oil production, add 0.1-0.4% of the treatment agent; the treatment agent includes rice husk ash and quicklime;

[0053] S2 Subject the sewage from edible oil production with the treatment agent added in S1 to sufficient mixed gas flotation in the mixed gas flotation tank 1, for demulsification, flocculation, and phosphorus removal;

[0054] S3 Filter out solids and adsorb part of the grease from the sewage from edible oil production after sufficient mixed gas flotation with the treatment agent added in S2 through the stepped filter bag 2;

[0055] S4 Subject the filtered sewage from edible oil production in S3 to wetting coalescence and collision coalescence through the oil collector 3, and realize oil-water separation and adsorb grease by using the principle of a shallow tank;

[0056] S5 further separates the edible oil production wastewater after the oil is adsorbed in S4 into solid-liquid and water-oil by the static tank 4, and separates the oil pollution to one side through the partition 4-1. The water in the lower layer is drained to the upper outlet for discharge, and the obtained wastewater meets the discharge standard.

[0057] The ratio of rice husk ash to quicklime is selected according to the phosphorus content and oil content of edible oil production wastewater:

[0058] a When phosphorus content is higher than 100ppm, oil content is higher than 2000ppm, and COD is greater than 20000ppm, the addition ratio of rice husk ash to quicklime is 3:1;

[0059] b. When the phosphorus content is 50-100ppm, the oil content is less than 2000ppm, and the COD is 10000-20000ppm, the addition ratio of rice husk ash to quicklime is (2-3): (0.6-0.8);

[0060] c When the phosphorus content is less than 50ppm, there is a little or no oil, and the COD is less than 10000ppm, the addition ratio of rice husk ash to quicklime is within 1:0.4.

[0061] principle:

[0062] By adding rice husk ash and quicklime in different proportions according to the phosphorus content and oil content of edible oil production wastewater, each unit producing wastewater can be treated separately, avoiding the overall deterioration of water quality after mixing of each monomer wastewater, and avoiding increased treatment difficulty and operating costs.

[0063] The sewage is fully mixed with the added rice husk ash and quicklime for flotation through the mixed flotation tank 1, achieving the effects of demulsification, flocculation and phosphorus removal; by setting the upper and lower partitions with small intervals, diversion and full mixing can be achieved. The stepped filter bags 2 made of lipophilic materials are used for filtering and solid-liquid separation layer by layer, filtering out solid sediments while absorbing most of the grease; because the filter bags have a small mesh size, they can be left to stand while filtering, and when the water flow height reaches the opening of the filter bag, it begins to overflow to the next filter bag; and the sewage filtered from the filter bag is guided by the water receiving plate and flows out from the outlet. The internal structure of the oil collector 3 made of lipophilic material is a bow-shaped design. It utilizes the principles of wetting and agglomeration, collision and agglomeration, and shallow pools. Through wetting, adsorption, collision, aggregation and removal, it can achieve the effect of two-phase separation and adsorption of grease in a short time; the stilling tank 4 is divided into left and right chambers by the partition of the stilling tank 4. The sewage is first introduced into the right chamber, and the sewage further reacts with quicklime / rice husk ash. After standing, the oil and water are separated, the grease floats on the upper layer, and the solid sediment is deposited at the bottom. The partition is opened upward, and the sewage is drained from the bottom to the left chamber, the oil is isolated in the right chamber, and the sewage is discharged from the outlet above the left chamber, successfully separating the oil and solid sediment.

[0064] The entire process does not require the addition of chemical agents such as acid, demulsifier, flocculant, etc.; the output of solid precipitate is small and can be used as a raw material for biological fertilizer; the treated sewage meets the discharge requirements and can be directly discharged; compared with traditional processes, the process cost of the present invention is low.

[0065] The sewage treatment device of the present invention can realize continuous industrial operation, has a short treatment time, and effectively realizes solid-liquid separation and water-oil separation of edible oil production sewage.

[0066] Example 1

[0067] One ton of edible oil production wastewater containing 2500ppm oil, 140ppm phosphorus and 25000ppm COD is treated by the device of the present invention and in conjunction with the above-mentioned method steps, wherein 3kg of rice husk ash and 1kg of quicklime are used. The wastewater discharged after treatment is tested and found to contain 9ppm oil, 4.5ppm phosphorus and 260ppm COD. The total process cost is 3.6 yuan and the treatment time is 1.5h.

[0068] Example 2

[0069] One ton of edible oil production wastewater containing 1600 ppm oil, 60 ppm phosphorus and 15000 ppm COD was treated by the device of the present invention and in conjunction with the above-mentioned method steps, wherein 2 kg of rice husk ash and 0.8 kg of quicklime were used. The wastewater discharged after treatment was tested and found to contain 8.2 ppm oil, 3.9 ppm phosphorus and 259 ppm COD. The total process cost was 3.3 yuan and the treatment time was 1.5 hours.

[0070] Example 3

[0071] One ton of edible oil production wastewater containing 1600ppm oil, 60ppm phosphorus and 15000ppm COD was treated by the device of the present invention and in conjunction with the above-mentioned method steps, wherein 3kg of rice husk ash and 0.6kg of quicklime were added. The wastewater discharged after treatment was tested and found to contain 8.3ppm oil, 4.2ppm phosphorus and 261ppm COD. The total process cost was 3.2 yuan and the treatment time was 1.5h.

[0072] Example 4

[0073] One ton of edible oil production wastewater containing 50 ppm oil, 30 ppm phosphorus and 6000 ppm COD was treated by the device of the present invention and in conjunction with the above-mentioned method steps, wherein 1 kg of rice husk ash and 0.4 kg of quicklime were added. The wastewater discharged after treatment was tested and found to contain 7 ppm oil, 2.5 ppm phosphorus and 200 ppm COD. The process cost of the entire process was 3 yuan in total and the treatment time was 1.5 hours.

[0074] Comparative Example 1

[0075] The sewage from the refining workshop, oil pressing workshop and other factory areas is mixed in a mixed flotation tank 1 to obtain 1 ton of edible oil production sewage with an oil content of 2500ppm, a phosphorus content of 140ppm and a COD of 25000ppm. 0.1kg of sulfuric acid is added to adjust the pH to 4-5 for oil removal, 8kg of quicklime is added to adjust the pH to 8-9 for flocculation, and 0.1kg of flocculant PAC / PAM is added for further flocculation. The sewage discharged after solid-liquid separation is tested and found to contain 9ppm oil, 4.5ppm phosphorus and 265ppm COD. The total process cost is 12.6 yuan and the processing time is 9h.

[0076] Notes:

[0077] 1. The traditional process treatment method is to first mix the monomer wastewater, add sulfuric acid and stir to reduce the pH to less than 5 for demulsification, and then let it stand for a long time in the sedimentation tank to separate the oil and water. 2 or 3 sedimentation tanks are rotated for intermittent treatment, and the operation separation time is about 2 hours. In case of high oil content and severe emulsification, the oil-water separation is not obvious, which will increase the subsequent amount of quicklime.

[0078] 2. The present invention adds rice husk ash and quicklime in different proportions according to different sewage qualities. The sewage mixed with rice husk ash and quicklime can achieve demulsification effect by mixing for about 15 minutes with special equipment. The demulsified sewage can be separated from rice husk ash, oil and water through the subsequent process. The whole treatment process is fast and continuous, and there is no need to add acid to increase the difficulty of subsequent treatment stages.

[0079] 3. The demulsification effect is better under high temperature conditions. When the sewage temperature is >50 degrees, the treatment effect will be better if rice husk ash is added, and the addition ratio will be small. Generally, the sewage temperature generated by most units of edible oil enterprises is as high as 50 degrees, and the oil and phosphorus content are high.

[0080] Summarize:

[0081] The above examples and comparative examples are compared on the basis of ensuring that the treated sewage meets the requirements (the result data fluctuates, but the difference is not large). According to examples 1-4 and the traditional process, the process cost of treating 1 ton of sewage in examples 1-4 is 3-4 yuan, and the cost of the traditional process is 12 yuan, which shows that the cost is significantly reduced. The time for treating 1 ton of sewage in examples 1-4 is 1.5 hours, which significantly saves time compared to the 9 hours of the traditional process.

[0082] It should be noted that the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0083] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is limited by the appended claims and their equivalents.

Claims

1. A edible oil production wastewater treatment system, It is characterized in that The invention comprises a lime adding device (1-4), a mixed air flotation tank (1), a stepped filter bag (2), an oil collector (3) and a static tank (4), wherein the lime adding device (1-4) is arranged on the sewage inlet of the mixed air flotation tank (1), and the lime adding device (1-4) is used to add quicklime and rice husk ash into the mixed air flotation tank (1), and the outlet of the mixed air flotation tank (1) is connected to the inlet of the stepped filter bag (2), and the oil collector (3) is provided with a multilayer plate inside, the surface of the multilayer plate is made of an oleophilic material, and the multilayer plates are fixed to the left and right side walls of the oil collector (3) at intervals, so as to separate the oil collector (3) to form an arch-shaped space, and the arch-shaped space leads to the sewage inlet at the top and the sewage outlet at the bottom; The static pool (4) comprises a partition, wherein the partition (4-1) is arranged at the top of the static pool (4), fits the front and rear walls of the static pool (4), leaves a gap with the bottom, and separates the static pool (4) into left and right chambers, wherein the water inlet (4-2) is located at the top of the right chamber (4-4), and the water outlet (4-3) is located at the upper part of the left side wall of the left chamber (4-5). The bottom of the static pool (4) is paved with rice husk ash and quicklime. The partition (4-1) is slidably connected to the top of the static pool (4) and is provided with a sealing strip. The outlet of the stepped filter bag (2) is connected to the sewage inlet of the oil collector (3), and the sewage outlet of the oil collector (3) is connected to the water inlet of the static pool (4). The stepped filter bag (2) comprises a main body (2-1), a plurality of filter bags (2-2) and a water receiving plate (2-3); the filter bags (2-2) are fitted to each other and are arranged in a stepped manner along the right side wall (2-4) to the left outlet; the filter bags (2-2) are fixed to the front and rear side walls of the main body (2-1); a water receiving plate (2-3) is fixed to the main body (2-1); the water receiving plate (2-3) is located below the filter bag (2-2) and has a gap with the filter bag (2-2); the water receiving plate (2-3) connects the right side wall (2-4) to the left outlet; the filter bag (2-2) is a screen structure made of an oleophilic material.

2. A edible oil production wastewater treatment system according to claim 1, It is characterized in that The mixed air flotation tank (1) comprises an upper baffle (1-2) and a lower baffle (1-1); the lower baffle (1-1) is fixed to the bottom of the mixed air flotation tank (1), fits the front and rear walls of the mixed air flotation tank (1), and leaves a gap with the top; the upper baffle (1-2) is fixed to the top of the mixed air flotation tank (1), fits the front and rear walls of the mixed air flotation tank (1), and leaves a gap with the bottom; the lower baffle (1-1) is located on the left side of the upper baffle (1-2), and the upper baffle (1-2) and the lower baffle (1-1) are used in combination to divide the mixed air flotation tank (1) into a plurality of chambers; an air flotation plate (1-3) is provided at the bottom of the mixed air flotation tank (1), and a plurality of small holes are distributed on the air flotation plate (1-3) and are connected to compressed air; the sewage inlet is located on the left side wall of the mixed air flotation tank (1), and a ash adding device (1-4) is provided on the sewage inlet, and the sewage outlet is located on the upper right side of the mixed air flotation tank (1).

3. An edible oil production wastewater treatment system according to claim 1 or 2, It is characterized in that The oleophilic material is specifically a meltblown cloth material.

4. A process for treating wastewater from edible oil production, It is characterized in that Using the edible oil production wastewater treatment system as described in any one of claims 1 to 3, the treatment process comprises the following steps: S1 transports the edible oil production wastewater to the mixed flotation tank (1), and adds 0.1-0.4% of a treatment agent based on 100% by weight of the edible oil production wastewater; the treatment agent comprises rice husk ash and quicklime; S2 passes the edible oil production wastewater with the treatment agent added in S1 through a mixed flotation tank (1) to fully mix with the added treatment agent for flotation, demulsification, flocculation and phosphorus removal; S3 is to mix the edible oil wastewater in S2 with the added treatment agent and float it through a stepped filter bag (2) to filter out solids and absorb part of the oil; S4 removes grease from the edible oil production wastewater filtered in S3 through an oil collector (3); S5 further separates the edible oil production wastewater after the oil is adsorbed in S4 into solid-liquid and water-oil separation by a static tank (4), and separates the oil pollution to one side through a partition (4-1), and the water in the lower layer is drained to the upper outlet for discharge, and the obtained wastewater meets the discharge standard; The ratio of rice husk ash and quicklime in the mixed flotation tank is selected according to the phosphorus content and oil content of edible oil production wastewater: a When phosphorus content is higher than 100ppm, oil content is higher than 2000ppm, and COD is greater than 20000ppm, the addition ratio of rice husk ash to quicklime is 3:1; b. When the phosphorus content is 50-100ppm, the oil content is less than 2000ppm, and the COD is 10000-20000ppm, the addition ratio of rice husk ash to quicklime is (2-3): (0.6-0.8); c When the phosphorus content is less than 50ppm, there is a little or no oil, and the COD is less than 10000ppm, the addition ratio of rice husk ash to quicklime is within 1:0.4.

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