A high oil content wastewater treatment system and method

Abstract

The present application relates to the technical field of oilfield produced water purification, and particularly relates to a high-oil-content sewage treatment system and method. The high-oil-content sewage treatment system comprises an oil-water separation module and a sewage treatment module. The high-oil-content sewage treatment system provided by the present application first realizes the separation of oil and water through the oil-water separation module, then realizes the flocculation separation of residual oil stains and pollutants through the sewage treatment module, and finally realizes the harmless treatment of sewage by electrocatalytic oxidation degradation of organic matter and nitrogen and other pollutants in the sewage.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oilfield produced water purification, and particularly relates to a high-oil-content sewage treatment system and method. BACKGROUND

[0002] The information disclosed in this Background section is for the purpose of generally presenting the context of the present application, and merely represents background art. The information is not to be taken as an acknowledgement or any form of suggestion that this information forms prior art merely by virtue of its inclusion in this section.

[0003] Oilfield oily sewage has large quantity, complex composition, difficult degradation and wide pollution range. In particular, the large-scale application of tertiary oil recovery technology in oilfields has generated a large amount of high-emulsified, high-viscosity and high-oil-content sewage, which has exacerbated the difficulty of oilfield sewage treatment. The oil in this type of sewage has various distribution forms, including floating oil, dispersed oil and emulsified oil. Large-particle-size oil droplets are relatively easy to remove in conventional separation, while small-particle-size oil droplets need to be effectively separated by other technologies. In addition to oil substances, high-oil-content sewage also contains a large amount of organic matter and nitrogen pollutants that are difficult to degrade. If the oily sewage is directly discharged, it will cause serious environmental pollution and have adverse effects on humans, animals and plants and the ecological system. For the treatment of such sewage, a single treatment method cannot completely adapt to the removal of all pollutants, and the existing sewage treatment technology mainly uses a single flocculation technology or oxidation technology to realize oil-water separation and organic matter degradation. At the same time, the flocculation process adds flocculants and other chemical agents to the water body. This treatment technology increases the treatment cost and causes secondary pollution to the water body. Therefore, research on efficient and clean oilfield sewage treatment technology has become a new direction for oilfield development and ecological environment protection. SUMMARY

[0004] To solve the above problems, the present application provides a high-oil-content sewage treatment system and method.

[0005] To achieve the above technical purposes, the present application adopts the following technical solutions:

[0006] In a first aspect, the present application provides a high-oil-content sewage treatment system, comprising:

[0007] an oil-water separation module and a sewage treatment module;

[0008] The oil-water separation module comprises a first oil-water separation unit and a second oil-water separation unit. The first oil-water separation unit comprises a solid-liquid separation tank, which comprises a first outlet and a second outlet, and the first outlet is connected to a crude oil dehydrator. The second oil-water separation unit comprises a coalescence separator and a settling tank, and the coalescence separator is connected to the crude oil dehydrator. The coalescence separator is connected to the second outlet.

[0009] The outlet of the coalescing separator is connected with the inlet of the settling tank.

[0010] The settling tank comprises a fourth outlet connected with the crude oil dewatering device and a fifth outlet connected with the flow disrupter.

[0011] The crude oil dewatering device comprises a sixth outlet connected with the flow disrupter.

[0012] The flow disrupter is a spiral flow disrupter comprising a water delivery pipe, and helical blades are arranged on the inner wall of the water delivery pipe along the length direction of the water delivery pipe.

[0013] The sewage treatment module comprises a flocculation separation unit and an electro-catalytic oxidation unit.

[0014] The flow disrupter is sequentially connected with the flocculation separation unit and the electro-catalytic oxidation unit.

[0015] In a second aspect of the present application, a method for treating high-oil-content sewage is provided, comprising:

[0016] Separating oil and water from the high-oil-content sewage, and collecting oil and sewage after oil separation, respectively;

[0017] Electrolyzing the sewage after oil separation, magnetically separating flocculants, and then electro-catalytically oxidizing the effluent after separating the flocculants.

[0018] The present application has the following beneficial effects:

[0019] The high-oil-content sewage treatment system provided by the application first realizes oil-water separation through an oil-water separation module, removes a large amount of floating oil and dispersed oil in the sewage, and then realizes flocculation and separation of residual oil stains and pollutants through a sewage treatment module, and finally realizes harmless treatment of the sewage by electrocatalytic oxidation degradation of organic matter and nitrogen and other pollutants in the sewage. Specifically, high-oil-content sewage first enters a solid-liquid separation tank of a first oil-water separation unit for solid-liquid separation, a large amount of floating oil, sewage containing a small amount of floating oil, and solid impurities such as silt are separated out in the solid-liquid separation tank; the floating oil enters a crude oil dehydrator, the sewage containing a small amount of floating oil enters a second oil-water separation unit for water-oil separation again, and the solid impurities such as silt enter a blowdown pipeline. The second oil-water separation unit separates a small amount of floating oil and a large amount of sewage, and the small amount of floating oil also enters the crude oil dehydrator, in which the floating oil is dehydrated, and a large amount of crude oil with low water content after dehydration can be recycled and treated, and the remaining sewage and the sewage separated out from the second oil-water separation unit enter a flocculation separation unit for electroflocculation, so that small-particle-size emulsified oil is formed into flocculation bodies with a large particle size, and is further removed through a magnetic separator, and the sewage after flocculation separation enters an electrocatalytic oxidation unit for harmless treatment. This multi-level separation design significantly improves the sewage treatment effect, especially the removal of emulsified oil with a particle size in the micron level and other pollution elements still existing after coalescence separation, and solves the problem that traditional sewage treatment technology cannot achieve deep treatment in high-oil-content sewage treatment.

[0020] (2) In the application, most of the suspended oil samples can be removed through twice oil-water separation treatment, the high oil content in the water body is reduced, the burden of subsequent flocculation, separation and oxidation treatment is reduced, a large amount of pollutants will not be attached to the subsequent electrode plate to cause passivation phenomenon, and the electrochemical reaction can be ensured to proceed normally. The sewage after sedimentation enters a flocculation separation and catalytic oxidation unit, and small-particle-size emulsified oil, organic pollutants and nitrogen pollutants in the sewage are efficiently separated, and compared with a single treatment technology, complete separation treatment can be achieved.

[0021] (3) Compared with the previous sewage treatment technology, through the modular design, including solid-liquid separation, coalescence separation, electrocoagulation, magnetic separation and electro-catalytic oxidation module. Each module is independent and connected with each other, and can be flexibly adjusted and combined according to the different oil content and pollution characteristics of the sewage, so as to adapt to different processing requirements. For example, when treating sewage with high oil content, the working time of coalescence separation can be increased, and for sewage with high organic matter content, the treatment time of electro-catalytic oxidation can be extended or recycled again. The whole treatment process can gradually process oil droplets in different particle size ranges, gradually reduce the oil content and pollutant content in the sewage, and multiple processes cooperate to establish good conditions for subsequent processing; no chemical reagent is added in the whole separation and treatment process, the method of combining physical separation and electro-catalytic oxidation is used, the secondary pollution to the water body is reduced, and the green and environmental protection treatment goal of the sewage is realized. BRIEF DESCRIPTION OF DRAWINGS

[0022] The accompanying drawings, which form a part of this specification, are included to provide a further understanding of the application and are incorporated herein for explanation.

[0023] Figure 1 It is a structure schematic diagram of the high-oil-content sewage treatment system of the application, wherein 1 is a solid-liquid separation tank, 2-1 is a first centrifugal pump, 2-2 is a second centrifugal pump, 3 is a heater, 4 is a coalescence separator, 5 is a sedimentation tank, 6 is a crude oil dewatering device, 7 is an electrolytic cell, 8 is a magnetic separator, 9 is an electro-catalytic oxidation tank, 10-1, 10-2, 10-3, 10-4, 10-5, 10-6, 10-7, 10-8, 10-9, 10-10 are flow valves, 11-1 is a first blowdown valve, 11-2 is a second blowdown valve, 11-3 is a third blowdown valve, 12 is a flow disrupter, 12-1 is a water conveying pipe, and 12-2 is a spiral blade.

[0024] Figure 2 It is a structure schematic diagram of the flow disrupter, wherein 12-1 is a water conveying pipe, and 12-2 is a spiral blade. DETAILED DESCRIPTION

[0025] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the application. Unless otherwise specified, all technical and scientific terms used in the present application have the same meaning as generally understood by those skilled in the art to which the present application belongs.

[0026] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, components, and / or groups thereof, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0027] In a first exemplary embodiment of the present application, a high oil content wastewater treatment system is provided, comprising:

[0028] an oil-water separation module and a wastewater treatment module;

[0029] wherein the oil-water separation module comprises a first oil-water separation unit and a second oil-water separation unit; the first oil-water separation unit comprises a solid-liquid separation tank, the solid-liquid separation tank comprises a first outlet and a second outlet, the first outlet is connected to a crude oil dehydrator; the second oil-water separation unit comprises a coalescence separator and a settling tank, the coalescence separator is connected to the crude oil dehydrator; the coalescence separator is connected to the second outlet; the wastewater treatment module comprises a flocculation separation unit and an electro-catalytic oxidation unit.

[0030] In one or more embodiments, the solid-liquid separation tank further comprises a third outlet, the third outlet is in communication with a blowdown line.

[0031] In one or more embodiments, the second outlet of the solid-liquid separation tank is connected to an inlet of a heater, an outlet of the heater is connected to an inlet of the coalescence separator.

[0032] In one or more embodiments, an outlet of the coalescence separator is connected to an inlet of the settling tank.

[0033] Preferably, the settling tank comprises a fourth outlet and a fifth outlet, the fourth outlet is connected to the crude oil dehydrator, the fifth outlet is connected to a flow disrupter.

[0034] Further preferably, the flow disrupter is connected to the flocculation separation unit.

[0035] Further preferably, the crude oil dehydrator comprises a sixth outlet, the sixth outlet is connected to the flow disrupter.

[0036] Further preferably, the flow disrupter is a helical flow disrupter, the helical flow disrupter comprises a water delivery conduit, an inner wall of the water delivery conduit is provided with helical vanes along a length direction of the water delivery conduit.

[0037] In one or more embodiments, the flocculation separation unit comprises an electrolytic cell and a magnetic separator connected in sequence.

[0038] Preferably, the anode material of the electrolytic cell is iron-aluminum alloy.

[0039] In one or more embodiments, the electro-catalytic oxidation unit comprises an electro-catalytic oxidation tank; the electro-catalytic oxidation unit is connected with the flocculation separation unit.

[0040] In a second typical embodiment of the present application, a method for treating high-oil-content sewage water is provided, comprising:

[0041] Separating oil and water from the high-oil-content sewage water, collecting the oil and the sewage water after oil separation, respectively;

[0042] Electrolyzing the sewage water after oil separation, magnetically separating flocculants, and then electro-catalytically oxidizing the effluent after the flocculants are separated.

[0043] In one or more embodiments, the collected oil is recycled and treated.

[0044] In order to enable those skilled in the art to more clearly understand the technical solutions of the present application, the technical solutions of the present application will be described in detail below with specific examples.

[0045] Example 1

[0046] Reference Figure 1 A system for treating high-oil-content sewage water, comprising:

[0047] An oil-water separation module and a sewage treatment module;

[0048] The oil-water separation module comprises a first oil-water separation unit and a second oil-water separation unit; the first oil-water separation unit comprises a solid-liquid separation tank 1, which comprises a first outlet and a second outlet, and the first outlet is connected with a crude oil dehydrator 6 through a first centrifugal pump 2-1; the second oil-water separation unit comprises a coalescence separator 4 and a settling tank 5, and the coalescence separator 4 is connected with the crude oil dehydrator 6; the coalescence separator 4 is connected with the second outlet.

[0049] The sewage treatment module comprises a flocculation separation unit and an electro-catalytic oxidation unit.

[0050] The flow disrupter 12 is connected with the flocculation separation unit and the electro-catalytic oxidation unit in sequence.

[0051] The solid-liquid separation tank 1 further comprises a third outlet connected with the blowdown pipeline. The high-oil-content sewage first enters the solid-liquid separation tank of the first oil-water separation unit for solid-liquid separation. A large amount of floating oil, sewage containing a small amount of floating oil and solid impurities such as silt are separated in the solid-liquid separation tank. The floating oil enters the crude oil dewatering device through the first outlet, the sewage containing a small amount of floating oil enters the second oil-water separation unit through the second outlet for water-oil separation again, and the solid impurities such as silt enter the blowdown pipeline through the third outlet.

[0052] In the second oil-water separation unit, the second outlet of the solid-liquid separation tank 1 is connected with the inlet of the heater 3 through the second centrifugal pump 2-2, the outlet of the heater 3 is connected with the inlet of the coalescence separator 4, the outlet of the coalescence separator 4 is connected with the inlet of the settling tank 5. The settling tank 5 comprises a fourth outlet, a fifth outlet and a seventh outlet, the fourth outlet is connected with the crude oil dewatering device 6, the fifth outlet is connected with the flow disturber 12, and the seventh outlet is connected with the blowdown pipeline; the flow disturber is connected with the flocculation separation unit. The crude oil dewatering device 6 comprises a sixth outlet and an eighth outlet, the sixth outlet is connected with the flow disturber, and the eighth outlet is connected with the blowdown pipeline.

[0053] The sewage containing a small amount of floating oil discharged from the first outlet of the first oil-water separation unit enters the second oil-water separation unit for water-oil separation again. The sewage is first heated by the heater 3, and the viscosity and stability of the emulsion after heating are reduced, so that the dispersed oil can be effectively removed in the subsequent coalescence separation process. The heated sewage enters the coalescence separator 4, and the filler in the filler layer of the coalescence separator 4 is made of oleophilic and hydrophobic material. When the oil droplets in the sewage approach the oleophilic and hydrophobic material, they will adhere to the material. Subsequently, the oil droplets in the sewage will also adhere to the material or collide with the oil droplets on the material to form large oil droplets. When the oil droplets grow large enough, they will be separated from the surface of the material under the action of fluid drag force and flow out of the coalescence separator 4. The coalescence separation technology belongs to a physical separation technology, which can coalesce the small oil droplets in the sewage after removal of the floating oil into large oil droplets, and then remove a part of the small oil droplets in the sewage through sedimentation separation. Meanwhile, the treatment method will not pollute the environment. The sewage generated in the coalescence separator 4 enters the sedimentation tank 5 for sedimentation separation. After coalescence separation, the oil droplets coalesce and settle on the upper layer of the sewage to form a high-water-content floating oil layer and a small amount of solid impurities such as silt. The floating oil will enter the crude oil dewatering device 6 through the fourth outlet, the remaining sewage will enter the flow disruptor 12 through the fifth outlet, and a small amount of solid impurities will be connected to the sewage pipe through the seventh outlet. In the crude oil dewatering device 6, efficient dehydration of crude oil is realized through electric dehydration. A large amount of crude oil with low water content after dehydration can be recycled and treated again to prevent waste of oil resources. The sewage after dehydration enters the flow disruptor 12 through the sixth outlet. The traditional oil-water separation technology has poor treatment effect on high-emulsified sewage, especially in the case of high stability of the emulsion in the sewage, it is difficult to completely separate through conventional physical or chemical methods. The above multi-stage separation design significantly improves the oil-water separation effect, especially in the case that dispersed oil still exists in the sewage after simple removal of floating oil, which solves the problem of incomplete separation in the treatment of high-oil-content sewage in the traditional technology.

[0054] Reference Figure 2 FIG. 12 is a structural schematic diagram of the flow disruptor 12. In this embodiment, the flow disruptor 12 is a spiral flow disruptor, which includes a water conveying pipe 12-1, and the inner wall of the water conveying pipe is provided with spiral blades 12-2 along the length direction of the water conveying pipe. The sewage discharged from the sixth outlet of the crude oil dewatering device 6 collides and mixes with the sewage discharged from the fifth outlet of the sedimentation tank 5, and under the action of the spiral flow disruptor, the turbulence degree of the sewage is increased, so that the sewage entering the electrolytic cell can be better flocculated.

[0055] The flocculation separation unit comprises an electrolytic cell 7 and a magnetic separator 8 connected in sequence, and the magnetic separator 8 is connected with the sewage pipe. The anode material of the electrolytic cell 7 is an iron-aluminum alloy. The anode material is dissolved in the electrolysis process to generate corresponding metal ions, and the metal ions further form hydroxyl compounds with the hydroxyl ions generated by water electrolysis. The hydroxyl compounds coagulate and precipitate with suspended solids, oils and other substances in the wastewater to achieve the purpose of purifying the wastewater. At the same time, during the development of the oil field, there will be a certain amount of chloride ions. The chloride ions can produce CLO - In the subsequent electro-catalytic oxidation process, it can catalytically oxidize part of the oxidants in the wastewater into water, carbon dioxide and non-toxic small-molecule organic matter, thereby improving the removal rate of COD in the wastewater. At the same time, the hydroxyl compounds coagulate and precipitate with suspended solids, emulsified oil and other substances in the wastewater to form flocculation bodies with magnetism. When the sewage enters the magnetic separator 8, the flocculation bodies with magnetism are subjected to magnetic force by the magnetic field applied by the magnetic separator and then separated, thereby improving the overall separation effect. The separated solids enter the sewage pipe. Compared with other magnetic separation treatment methods, magnetic powder is added to the water body during the magnetic separation process, and a stirrer device is used to inoculate the flocculation bodies with the magnets. This method not only has a small treatment capacity, but also may cause insufficient stirring in the inoculation process of the magnetic powder and the flocculation bodies. Moreover, the magnetic powder cannot be completely recovered subsequently.

[0056] The electro-catalytic oxidation unit comprises an electro-catalytic oxidation tank 9. The electro-catalytic oxidation tank 9 is connected with the sewage pipe and the second centrifugal pump 2-2. The electro-catalytic oxidation treatment utilizes the catalytic activity of the anode and the oxidation groups or free radicals generated by the anode to directly oxidize and degrade the organic matter, nitrogen and other pollutants in the water, thereby realizing the harmless treatment of the sewage. When the treated sewage meets the discharge standard, it can be discharged. However, when the treated sewage cannot meet the discharge standard, the sewage in the electro-catalytic oxidation tank 9 continues to enter the second oil-water separation unit for subsequent treatment. The solid waste generated in the electro-catalytic oxidation tank 9 enters the sewage pipe.

[0057] To address the problem that traditional wastewater treatment systems often lack modular design and cannot flexibly adjust the operating parameters of different modules, resulting in poor adaptability to different types of wastewater, this method adopts a modular design. This allows each separation and treatment unit to be independently adjustable, and its operating parameters can be flexibly adjusted according to different wastewater characteristics, thereby improving the system's adaptability and flexibility. This system not only removes large oil droplets through conventional multi-stage oil-water separation but also introduces the synergistic effect of electrocoagulation, magnetic separation, and electrocatalytic oxidation. In most existing wastewater treatment systems, flocculants are used for flocculation, followed by magnetic powder stirring and then magnetic separation. Furthermore, flocculation and oxidation are usually performed separately. This invention, by tightly integrating different processes, achieves one-time treatment of suspended oil droplets, recalcitrant organic matter, and nitrogen, thereby improving overall treatment efficiency.

[0058] To better regulate the flow rate of wastewater in the entire system, flow valves are installed between the first outlet and the first centrifugal pump 2-1 (10-1), between the second outlet and the second centrifugal pump 2-2 (10-2), between the heater 3 and the coalescing separator 4 (10-3), between the coalescing separator 4 and the settling tank 5 (10-4), between the fourth outlet and the crude oil dehydrator 6 (10-5), between the fifth outlet and the baffle 12 (10-6), between the sixth outlet and the baffle 12 (10-7), between the electrolytic cell 7 and the magnetic separator 8 (10-8), between the magnetic separator 8 and the electrocatalytic oxidation tank 9 (10-9), and between the electrocatalytic oxidation tank 9 and the sewage pipe (10-10).

[0059] To facilitate better sewage discharge, a first sewage discharge valve (11-1) is installed between the magnetic separator 8 and the sewage discharge pipe, a second sewage discharge valve (11-2) is installed between the eighth outlet and the sewage discharge pipe, and a third sewage discharge valve (11-3) is installed between the seventh outlet and the sewage discharge pipe.

[0060] Example 2

[0061] A method for treating high-oil-content wastewater includes:

[0062] Oil-water separation is performed on high-oil-content wastewater to collect the oil and the wastewater after oil separation separately.

[0063] The wastewater after oil separation is subjected to electrolytic flocculation and magnetic separation to remove flocculants. The wastewater containing the separated flocculants is then subjected to electrocatalytic oxidation treatment.

[0064] Specifically:

[0065] (1) The high-oil-content sewage first enters the solid-liquid separation tank 1 of the first oil-water separation unit for solid-liquid separation. A large amount of floating oil, sewage containing a small amount of floating oil, and solid impurities such as silt are separated in the solid-liquid separation tank 1. The floating oil enters the crude oil dewatering device through the first outlet. The sewage containing a small amount of floating oil enters the second oil-water separation unit through the second outlet for water-oil separation again. The solid impurities such as silt enter the blowdown pipeline through the third outlet.

[0066] The sewage containing a small amount of floating oil discharged from the second outlet of the first oil-water separation unit enters the second oil-water separation unit for water-oil separation again. The sewage is first heated by the heater 3. The viscosity and stability of the emulsion of the heated sewage are reduced, so that the dispersed oil can be effectively removed in the subsequent coalescence separation process. The heated sewage enters the coalescence separator 4. The oil droplets with a small particle size in the sewage coalesce into oil droplets with a large particle size. The sewage produced in the coalescence separator 4 enters the settling tank 5 for settling separation. After the coalescence separation, the oil droplets coalesce and settle on the upper layer of the sewage to form a high-water-content floating oil layer and a small amount of solid impurities such as silt. The floating oil enters the crude oil dewatering device 6 through the fourth outlet. The remaining sewage enters the flow disturber 12 through the fifth outlet. A small amount of solid impurities such as silt are connected to the blowdown pipeline through the seventh outlet. In the crude oil dewatering device 6, a large amount of floating oil separated from the solid-liquid separation tank 1 and a small amount of floating oil produced in the coalescence separator 4 are subjected to efficient dehydration of crude oil by electric dehydration. A large amount of crude oil with a low water content after dehydration can be recycled and treated again to prevent waste of oil resources. The sewage after dehydration enters the flow disturber 12 through the sixth outlet. The sewage discharged from the crude oil dewatering device 6 through the sixth outlet collides and mixes with the sewage discharged from the settling tank 5 through the fifth outlet in the flow disturber 12, and then enters the sewage treatment module.

[0067] (2) The sewage enters the electrolytic cell 7 for electrolysis and preliminary oxidation of the pollutants in the sewage. Then, the sewage enters the magnetic separator 8 for separation. The solid after the separation enters the blowdown pipeline. The flocculated sewage finally enters the electro-catalytic oxidation tank 9 for electro-catalytic oxidation. The electro-catalytic oxidation unit can deeply degrade the refractory organic matter and nitrogen pollutants by generating oxidizing groups, thereby significantly improving the treatment effect of the sewage and achieving harmless treatment of the sewage. When the treated sewage meets the discharge standard, it can be discharged. However, when the treated sewage cannot meet the discharge standard, the sewage in the electro-catalytic oxidation tank 9 continues to enter the second oil-water separation unit for subsequent treatment.

[0068] Example 3

[0069] (1) The sewage entering the treatment system first enters the solid-liquid separation tank 1 of the first oil-water separation unit for gravity settling and solid-liquid separation. According to Stokes' settling equation The settling velocity of the large particle sediment material in the tank under the action of gravity can reach more than 5 cm / min, so it can quickly reach the tank bottom to realize solid-liquid separation. At the same time, the floating speed of the oil droplet with a very large particle size can reach more than 2 cm / min, and the oil and water can also quickly realize preliminary separation within 15-25 min. Thus, a large amount of floating oil, a small amount of floating oil-containing sewage and sediment and other solid impurities are separated in the solid-liquid separation tank 1. The floating oil enters the crude oil dewatering device through the first outlet, the small amount of floating oil-containing sewage enters the second oil-water separation unit through the second outlet to separate water and oil again, and the sediment and other solid impurities enter the blowdown pipeline through the third outlet.

[0070] (2) The second outlet of the first oil-water separation unit discharges a small amount of floating oil-containing sewage into the second oil-water separation unit to separate water and oil again. The sewage is first heated to 45-55 ℃ by the heater 3. According to the formula , as the temperature rises, the interfacial tension of the emulsion will decrease, the stability will decrease, the coalescence effect of the collision between the oil droplets will be enhanced, the oil droplets will be more easily floated and separated, and thus the subsequent coalescence separation can be enhanced. Similarly, the viscosity of the heated sewage is reduced, which is beneficial to the subsequent treatment. The sewage enters the coalescence separator 4. In the coalescence separator, the flow rate is controlled at 0.01-0.02 m / s. After 35-50 min of coalescence separation, the oil droplets with a small particle size in the sewage are coalesced into oil droplets with a large particle size. The sewage produced in the coalescence separator 4 enters the settling tank 5 for settling separation. After coalescence separation, the oil droplets coalesce and settle on the upper layer of the sewage to form a high-water-content floating oil layer and a small amount of sediment and other solid impurities. The floating oil enters the crude oil dewatering device 6 through the fourth outlet. The remaining sewage enters the flow disruptor 12 through the fifth outlet. A small amount of sediment and other solid impurities are connected to the blowdown pipeline through the seventh outlet. In the crude oil dewatering device 6, a large amount of floating oil separated from the solid-liquid separation tank 1 and a small amount of floating oil produced in the coalescence separator 4 are subjected to efficient dehydration of crude oil by electric dehydration. A large amount of crude oil with low water content after dehydration can be recycled and treated again to prevent waste of oil resources. The sewage after dehydration enters the flow disruptor 12 through the sixth outlet. The sewage discharged from the crude oil dewatering device 6 through the sixth outlet and the sewage discharged from the settling tank 5 through the fifth outlet collide and mix in the flow disruptor 12 and enter the sewage treatment module.

[0071] (3) The sewage enters the electrolytic cell 7 for electrolysis. The current density in the electrolytic cell is 10-100 A / m 2 . The reaction time is 45-60 min. Part of the pollutants are removed by the previous oil-water separation, and the pollution degree is reduced. The flocculation current density is set to 40 A / m 2, if the pollution degree is higher, the current density can be increased. In the process of electrocoagulation, the iron or aluminum metal on the anode electrode loses electrons to generate metal ions, which combine with hydroxyl ions in the electrolyte to generate highly active flocculation groups Fe(OH)2 - and Al(OH)3 - These groups have strong adsorption capacity and can capture suspended particles and colloidal substances in wastewater through the grid structure, thereby achieving efficient flocculation and pollutant removal; at the cathode, water molecules are reduced to generate hydrogen gas (H2), and the generated bubbles can assist flocculation and promote the floating of pollutants. After the electrolytic cell performs flocculation, the flocculation enters the magnetic separator 8 for separation. The magnetic separator uses electromagnetic equipment, and the power supply current is 1-20 A. To meet the treatment of different magnetic flocculation bodies, the magnetic field strength is set to 5-100 T. The high gradient magnetic field can remove small flocculation bodies within 5-50 μm. The separated solids enter the sewage pipeline. Compared with other magnetic separation treatment methods, magnetic powder is added to the water body during the magnetic separation process, and the stirrer equipment is used to inoculate the flocculation body with the magnet. This method not only has a small treatment capacity, but also may cause insufficient stirring during the inoculation of the magnetic powder and the flocculation body. At the same time, the magnetic powder cannot be completely recovered subsequently; the turbulence device is used to make the wastewater entering the electrolytic cell have sufficient turbulent intensity, so that the water body is fully mixed during the "electrical inoculation" process, and there is no dead angle. At the same time, the problem that the treatment capacity is not limited by the stirring equipment is solved.

[0072] (4) The separated wastewater finally enters the electro-catalytic oxidation tank 9 for electro-catalytic oxidation. The current density in the electro-catalytic oxidation tank is adjusted to 100-800 A / m 2 , the reaction time is 35-50 min, the anode selects a ruthenium-iridium coated titanium (Ru-Ir / Ti) electrode with strong corrosion resistance, which ensures efficient electrochemical reaction and corrosion resistance. At the anode, water molecules (H2O) are electrolyzed to generate hydroxyl radicals (·OH) with strong oxidizing properties. This radical can rapidly oxidize organic pollutants and decompose them into carbon dioxide (CO2) and water (H2O), as follows: , ; similarly, chloride ions are oxidized to generate hypochlorous acid (HClO) and hypochlorite (ClO⁻), which then acts as a strong oxidizing agent to degrade organic matter and ammonia nitrogen, , The series of reactions thus oxidize and degrade organic matter, nitrogen and other pollutants in water, realize harmless treatment of the wastewater, reduce impurities in the wastewater in the early stage, and make the strong oxidants such as hydroxyl radicals (·OH) and hypochlorous acid (HClO) generated in the electro-catalytic oxidation process more concentratedly act on the refractory dissolved organic matter and ammonia nitrogen, so that the utilization efficiency of the oxidants is improved, and the removal effects of COD and ammonia nitrogen are more remarkable.

[0073] In the present embodiment, the initial oil content of the wastewater entering the treatment system is 1500 mg / L, the suspended matter content is 180 mg / L, and the ammonia nitrogen content is 50 mg / L. The wastewater first enters the solid-liquid separation tank 1 of the first oil-water separation unit and is subjected to gravity sedimentation for 20 min. The floating oil enters the crude oil dewatering device through the first outlet. The wastewater is first heated to 50 ℃ by the heater 3 and then enters the coalescence separator 4. The oil content of the wastewater at the inlet of the coalescence separator is 600 mg / L, and the suspended matter content is 60 mg / L. In the coalescence separator, the wastewater flow rate is 0.02 m / s. After being subjected to coalescence separation for 40 min, the wastewater enters the sedimentation tank. The floating oil in the tank enters the crude oil dewatering device 6 through the fourth outlet. The wastewater in the tank enters the flow disturber 12 through the fifth outlet and is mixed with the wastewater from the crude oil dewatering device 6, and then enters the electrolytic cell 7 for electrolysis. The initial oil content at the inlet of the electrolytic cell is 200 mg / L, the suspended matter content is 25 mg / L, and the ammonia nitrogen content is 45 mg / L. At the same time, the current density in the electrolytic cell ranges from 40 A / m 2 to 50 A / m, and the reaction time is 50 min. After flocculation in the electrolytic cell, the flocculation is separated in the magnetic separator 8. The magnetic field strength is set to 20 T. The high-gradient magnetic field can remove flocculation with a small particle size. The separated wastewater finally enters the electro-catalytic oxidation tank 9 for electro-catalytic oxidation. At this time, the oil content at the inlet is reduced to 20 mg / L, the suspended matter content is 10 mg / L, and the ammonia nitrogen content is 40 mg / L. In the electro-catalytic oxidation cell, the current density is adjusted to range from 600 A / m 2 to 700 A / m, and the reaction time is 40 min. The final treatment effect is shown in the following table.

[0074] Table 1 Treatment effect of various pollutants

[0075]

[0076] Table 2 Detection of other substances before and after wastewater treatment

[0077]

[0078] The above merely provides the preferred embodiments of the present application, and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the principles and technical scope of the present application shall fall into the scope of the present application.

Claims

1. A high oil content wastewater treatment system, characterized by, The application relates to an oil-water separation module and a sewage treatment module. The oil-water separation module comprises a first oil-water separation unit and a second oil-water separation unit. The first oil-water separation unit comprises a solid-liquid separation tank, the solid-liquid separation tank comprises a first outlet and a second outlet, the first outlet is connected with a crude oil dehydrator, the second oil-water separation unit comprises a coalescence separator and a settling tank, the coalescence separator is connected with the crude oil dehydrator, and the coalescence separator is connected with the second outlet. The outlet of the coalescence separator is connected with the inlet of the settling tank. The settling tank comprises a fourth outlet and a fifth outlet, the fourth outlet is connected with the crude oil dehydrator, and the fifth outlet is connected with a flow disturber. The crude oil dehydrator comprises a sixth outlet, the sixth outlet is connected with the flow disturber. The flow disturber is a spiral flow disturber, the spiral flow disturber comprises a water conveying pipeline, and the inner wall of the water conveying pipeline is provided with spiral blades along the length direction of the water conveying pipeline. The sewage treatment module comprises a flocculation separation unit and an electro-catalytic oxidation unit. The flow disturber is connected with the flocculation separation unit and the electro-catalytic oxidation unit in sequence. The flocculation separation unit comprises an electrolytic cell and a magnetic separator connected in sequence. The anode material of the electrolytic cell is iron-aluminum alloy. The solid-liquid separation tank further comprises a third outlet, the third outlet is connected with a sewage discharge pipeline.

2. The high oil content wastewater treatment system of claim 1, wherein, Alternatively, the second outlet of the solid-liquid separation tank is connected with the inlet of a heater, the outlet of the heater is connected with the inlet of the coalescence separator. The electro-catalytic oxidation unit comprises an electro-catalytic oxidation tank, and the outlet of the electro-catalytic oxidation unit is connected with the second oil-water separation unit.

3. The high oil content wastewater treatment system of claim 1, wherein, The application relates to an oil-water separation module and a sewage treatment module.

4. The high oil content wastewater treatment method of the high oil content wastewater treatment system according to any one of claims 1 to 3, characterized by, The application relates to an oil-water separation module and a sewage treatment module. The application relates to an oil-water separation module and a sewage treatment module. The application relates to an oil-water separation module and a sewage treatment module.

5. The method of claim 4, wherein the high oil content wastewater is treated by a method comprising: ​

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