Multi-stage modular oily wastewater purification equipment and purification method

Abstract

The invention discloses multistage modularized oily wastewater purification equipment and a purification method. The multistage modularized oily wastewater purification equipment comprises an initial sedimentation tank, an oil separation tank, a rotational flow dissolved air flotation mechanism, a double-membrane separation mechanism, a biological treatment mechanism and a tail end filter which are communicated in sequence, the rotational flow dissolved air flotation mechanism comprises an air flotation treatment tank, a hollow air conveying ring shell is fixed to the bottom in the air flotation treatment tank, and a plurality of air conveying nozzles communicated with the interior of the air conveying ring shell are fixed to the top of the air conveying ring shell; the double-membrane separation mechanism comprises double-membrane separation temporary storage barrels which are arranged in pairs and vertically extend, a double-membrane separation containing barrel which horizontally extends is fixed to the position, close to the lower end, between the double-membrane separation temporary storage barrels, and an oil phase separation partition plate and a water phase separation partition plate are fixed in the double-membrane separation containing barrel; the equipment has efficient oil removal performance, is provided with multiple treatment stages, can effectively remove oil drops with various specifications and particle sizes in oil-containing wastewater through multi-stage treatment, and can adapt to treatment of various oils and water quality.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a multi-stage modular oily wastewater purification device and a purification method. Background Art

[0002] Oily wastewater mainly comes from industries such as petroleum, petrochemicals, steel, coking, gas generation stations, mechanical processing, and shipping. Oily wastewater pollutes the environment and water bodies in many ways. Oil pollutants often contain aromatic hydrocarbons, and these organic pollutants are carcinogenic. The harm caused by oil pollutants to the ocean or rivers includes destroying the ecological balance, polluting the water sources for living and production, and destroying the coastal landscape; the pollution to the soil is reflected in causing soil compaction and destroying the growth environment of microorganisms in the soil. Each drop of oil can form an oil film of 0.25 square meters, isolating the atmosphere from the water, destroying the normal reoxygenation conditions, affecting the self-purification ability of the water body, and destroying the ecological environment of animals and plants in the water body, and causing death in severe cases.

[0003] The existing technology for purifying oily wastewater still has the problem of incomplete removal of the oil phase, and its purification equipment needs to be further improved and optimized. Summary of the invention

[0004] The object of the present invention is to provide a multi-stage modular oily wastewater purification device and a purification method, which can more thoroughly and effectively remove the oil phase in the oily wastewater.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A multi-stage modular oily wastewater purification device, comprising an initial sedimentation tank, an oil separator, a cyclone dissolved air flotation mechanism, a double membrane separation mechanism, a biological treatment mechanism and a terminal filter which are sequentially connected;

[0007] The cyclone dissolved air flotation mechanism comprises an air flotation treatment tank, a hollow air delivery ring shell is fixed at the bottom of the air flotation treatment tank, and a plurality of air delivery nozzles connected to the inside of the air delivery ring shell are fixed at the top of the air delivery ring shell;

[0008] An air flotation oil foam discharge pipe is provided on the top of the air flotation treatment tank, and an oil foam discharge control valve is provided on the air flotation oil foam discharge pipe;

[0009] The double membrane separation mechanism comprises a pair of double membrane separation temporary storage cylinders extending vertically, a horizontally extending double membrane separation receiving cylinder is fixed near the lower end between the double membrane separation temporary storage cylinders, and an oil phase separation partition and a water phase separation partition are fixed in the double membrane separation receiving cylinder;

[0010] A plurality of oil phase separation hydrophobic membranes are fixed on the oil phase separation partition, and a plurality of water phase separation hydrophilic membranes are fixed on the water phase separation partition;

[0011] The portion between the oil phase separation partition and the water phase separation partition in the double membrane separation container forms a mixing input space, the side of the oil phase separation partition away from the water phase separation partition forms an oil phase separation space, and the side of the water phase separation partition away from the oil phase separation partition forms a water phase separation space;

[0012] The mixed input space is connected to the inside of the double membrane separation temporary storage cylinder through the mixed input pipe;

[0013] The biological treatment mechanism comprises a vertically placed biological treatment outer cylinder shell, a biological treatment inner cylinder shell coaxially arranged therewith is fixed inside the biological treatment outer cylinder shell, an aerobic treatment space is formed between the inner side wall of the biological treatment outer cylinder shell and the outer side wall of the biological treatment inner cylinder shell, and an anaerobic treatment space is formed inside the biological treatment inner cylinder shell;

[0014] An aeration conveying ring shell is fixed at the bottom of the aerobic treatment space, and a plurality of aeration conveying nozzles connected with the interior of the aeration conveying ring shell are fixed at the top of the aeration conveying ring shell.

[0015] Preferably, a decompression control mechanism is provided in connection with the flotation treatment tank, the decompression control mechanism comprises a decompression control vacuum tank connected to the flotation treatment tank via a decompression control connecting pipe, the decompression control connecting pipe is provided with a decompression control valve, the decompression control vacuum tank is connected to a decompression control vacuum pump via a vacuum exhaust pipe, the vacuum exhaust pipe is provided with a vacuum exhaust control valve.

[0016] Note: The microbubbles generated by decompression can be more evenly dispersed in the oily wastewater, which helps to improve the removal rate of the oil phase.

[0017] Preferably, there are multiple decompression control vacuum tanks, and each decompression control vacuum tank is connected to the inside of the flotation treatment tank through an independent decompression control connecting pipe, and each decompression control vacuum tank is connected to a decompression control vacuum pump through a separate vacuum exhaust pipe.

[0018] Description: Setting up multiple pressure-reducing controlled vacuum tanks can carry out stepped cyclone dissolved gas treatment, so that a large number of microbubbles are precipitated in the oily wastewater in batches. These microbubbles are evenly dispersed in the oily wastewater. The suspended oil droplets in the oily wastewater can adhere to the microbubbles, and under the action of buoyancy, the microbubbles will float up with the oil droplets and gather on the surface of the oily wastewater, which can more thoroughly separate the oil droplets in the oily wastewater.

[0019] Preferably, a low-speed stirring mechanism is provided at the bottom of the air flotation treatment tank, and the low-speed stirring mechanism comprises a low-speed stirring drive shaft rotatably connected to the bottom of the air flotation treatment tank and extending vertically, the low-speed stirring drive shaft is fixedly connected to a low-speed stirring drive ring through a plurality of stirring drive connecting rods, and a plurality of vertically extending low-speed stirring drive plates are fixed to the upper end of the low-speed stirring drive ring;

[0020] A stirring drive housing is fixed at the lower end of the flotation treatment tank, and the lower end of the low-speed stirring drive shaft extends into the stirring drive housing. A low-speed stirring drive motor for driving the low-speed stirring drive shaft to rotate is fixed in the stirring drive housing.

[0021] Description: The low-speed stirring mechanism is used to drive and stir the oily wastewater in the flotation treatment tank, so that the oily wastewater as a whole rotates around the vertical axis of the flotation treatment tank to generate a vortex. Since water is denser than oil, under the centrifugal effect, the suspended oil droplets in the oily wastewater will be concentrated at the vertical axis of the flotation treatment tank, which is convenient for separating the collected oil droplets.

[0022] Preferably, the air-floating oil foam outer discharge pipe is connected to the top of the air-floating treatment tank through an outer discharge lifting mechanism, the top of the air-floating treatment tank has a vertically through-going closed matching sliding hole, the air-floating oil foam outer discharge pipe is slidably connected in the closed matching sliding hole, the outer discharge lifting mechanism includes an outer discharge lifting fixed cylinder fixed to the top of the air-floating treatment tank and with an opening facing upward, an outer discharge lifting sliding cylinder with an opening facing downward is slidably connected to the outer side of the outer discharge lifting fixed cylinder, and the outer discharge lifting sliding cylinder is fixedly connected to the air-floating oil foam outer discharge pipe;

[0023] An outer row lifting driving rod for driving the outer row lifting sliding cylinder to move up and down is arranged in the outer row lifting fixed cylinder.

[0024] Description: The external discharge lifting mechanism drives the lower end of the air-floating oil foam external discharge pipe to always be in contact with the liquid surface, so that the oil droplets accumulated on the surface of the oily wastewater can be effectively discharged.

[0025] Preferably, an air flotation pressure relief pipe connected to the interior of the air flotation treatment tank is fixed on the top of the tank, and an air flotation pressure relief control valve is provided on the air flotation pressure relief pipe.

[0026] Note: After the stage work is completed, the air flotation pressure relief pipe can be used to balance the pressure inside the air flotation treatment tank with the external atmospheric pressure to avoid explosion caused by unbalanced pressure difference.

[0027] Preferably, an auxiliary boosting separation mechanism is provided on the double membrane separation temporary storage cylinder, the auxiliary boosting separation mechanism comprises an auxiliary boosting piston slidably connected in the double membrane separation temporary storage cylinder, a vertically extending boosting piston driving rod is fixed to the top of the auxiliary boosting piston, and the upper end of the boosting piston driving rod extends upward to the outside of the double membrane separation temporary storage cylinder;

[0028] A booster drive fixed cylinder with an opening facing upward is fixed on the outside of the double-membrane separation temporary storage cylinder, a booster drive sliding cylinder is slidably connected inside the booster drive fixed cylinder, and the top of the booster drive sliding cylinder is fixedly connected to the upper end of the booster piston drive rod;

[0029] An auxiliary boost drive rod for driving the boost drive sliding cylinder to move up and down is arranged in the boost drive fixed cylinder.

[0030] Description: The auxiliary booster separation mechanism helps to force the oily wastewater in the double membrane separation temporary storage cylinder to flow more smoothly to the mixing input space.

[0031] Preferably, the auxiliary boosting piston has a plurality of forced circulation holes extending parallel to its axis, the lower end of the auxiliary boosting piston has a shaft connecting hole opening downward, an opening and closing disk shaft is rotatably connected in the shaft connecting hole, an opening and closing control disk is fixed at the lower end of the opening and closing disk shaft, the top of the opening and closing control disk is in pressure contact with the lower end of the auxiliary boosting piston, and the opening and closing control disk has a plurality of forced circulation matching holes extending parallel to the axis of the auxiliary boosting piston;

[0032] An opening and closing disk driving motor for driving the opening and closing disk rotating shaft to rotate is fixed in the rotating shaft connecting hole.

[0033] Description: It helps to force the suspended oil droplets in the oily wastewater in the double membrane separation temporary storage tube to merge together to form larger oil droplets and gather together to float to the surface of the oily wastewater, and helps to separate part of the oil phase in advance to reduce the workload of the oil phase separation hydrophobic membrane.

[0034] Preferably, a double membrane separation back pressure mechanism is provided outside the double membrane separation containing cylinder, the double membrane separation back pressure mechanism comprises a back pressure circulation ring shell fixed outside the double membrane separation containing cylinder, and the mixing input space is connected with the inside of the back pressure circulation ring shell through a plurality of back pressure circulation holes;

[0035] A back pressure external discharge pipe connected to the inside of the back pressure circulation ring shell is fixed on the outside of the back pressure circulation ring shell, and a separation back pressure control valve is provided on the back pressure external discharge pipe;

[0036] The other end of the back pressure external discharge pipe is connected to a reflux temporary storage tank, in which a delivery pump of prior art is provided, and the delivery pump is used to transport the wastewater temporarily stored in the reflux temporary storage tank back to the double membrane separation temporary storage cylinder for reflux treatment.

[0037] Description: The double membrane separation back pressure mechanism helps to make the oily wastewater flow more smoothly in the mixed input space, avoiding the formation of dead water in the mixed input space due to excessive workload, which affects the overall work efficiency.

[0038] Preferably, a multi-stage modular oily wastewater purification method, based on the above-mentioned multi-stage modular oily wastewater purification equipment, comprises the following steps:

[0039] S1. Sedimentation treatment:

[0040] The oily wastewater to be treated is transported to the initial sedimentation tank and allowed to settle for 2 to 6 hours;

[0041] S2. Oil separation treatment:

[0042] The oily wastewater after sedimentation treatment is transported to the grease trap for oil separation treatment at a flow rate of 2 to 5 mm / s;

[0043] S3, flotation treatment:

[0044] The oily wastewater after oil separation treatment is transported to the inside of the flotation treatment tank, and the input stops when the volume reaches 70%;

[0045] Aerate the oily wastewater in the flotation treatment tank, use an air delivery pump to deliver high-pressure air to the inside of the air delivery ring shell, the air pressure is set to 1Mpa, and the high-pressure air is discharged through each air delivery nozzle to form microbubbles, which flow from bottom to top in the oily wastewater. Oil droplets can attach to the microbubbles and float up with the microbubbles to gather on the surface of the oily wastewater;

[0046] At the same time, part of the air will dissolve in the oily wastewater. When the air pressure in the flotation tank reaches 1Mpa, aeration will stop.

[0047] At this time, the oily wastewater in the flotation treatment tank is in a state of dissolved gas saturation;

[0048] Open the oil foam discharge control valve and control its opening degree, so that the oil droplets gathered on the surface of the oily wastewater are discharged through the flotation oil foam discharge pipe under the high pressure of the flotation treatment tank;

[0049] When the lower end of the air-floating oil foam discharge pipe is provided with a liquid level sensor, the lower end of the air-floating oil foam discharge pipe is controlled to always be in contact with the liquid surface. During the discharge of high-pressure air through the air-floating oil foam discharge pipe, the oil droplets gathered on the surface of the oily wastewater can be discharged through the air-floating oil foam discharge pipe along with the air flow under the drive of the air flow. When the oil droplets gathered on the surface of the oily wastewater are discharged, the oil foam discharge control valve is closed;

[0050] S4, Cyclone Dissolved Gas Treatment:

[0051] Under the decompression effect of the decompression control mechanism, a large number of microbubbles will be precipitated from the oily wastewater in the saturated state of dissolved gas. These microbubbles are evenly dispersed in the oily wastewater. The suspended oil droplets in the oily wastewater can adhere to the microbubbles, and under the action of buoyancy, the microbubbles will float up with the oil droplets and gather on the surface of the oily wastewater.

[0052] At the same time, the low-speed stirring mechanism drives and stirs the oily wastewater in the flotation treatment tank, so that the oily wastewater as a whole rotates around the vertical axis of the flotation treatment tank to generate a vortex;

[0053] Since water has a greater density than oil, under the centrifugal effect, the suspended oil droplets in the oily wastewater will be concentrated on the vertical axis of the flotation treatment tank. The oil foam discharge control valve is opened and its opening is controlled so that the oil droplets concentrated on the vertical axis of the flotation treatment tank are discharged through the flotation oil foam discharge pipe.

[0054] Open the flotation wastewater output control valve, and the oily wastewater after cyclone dissolved air treatment is discharged through the flotation wastewater output pipe;

[0055] S5, membrane separation treatment;

[0056] The oily wastewater after the cyclone dissolved gas treatment is input into the double membrane separation temporary storage cylinders arranged in pairs. Under the action of the deadweight pressure, the oily wastewater in the double membrane separation temporary storage cylinders enters the mixing input space through the mixing input pipe;

[0057] The distance between the oil phase separation partition and the water phase separation partition is 5 mm;

[0058] When the oily wastewater flows in the narrow gap in the mixed input space, the water phase separation hydrophilic membrane will selectively remove the water phase in the oily wastewater, allowing the water phase to pass through the water phase separation hydrophilic membrane into the water phase separation space, resulting in an increase in the relative concentration of the oil phase in the oily wastewater in the mixed input space, which further intensifies the collision, aggregation and demulsification between the oil droplets, thereby increasing the permeation flux of the oil phase, and the oil phase in the oily wastewater will pass through the oil phase separation hydrophobic membrane into the oil phase separation space;

[0059] This allows the water phase and the oil phase in the oily wastewater to be separated;

[0060] S6. Biological treatment:

[0061] The oily wastewater is then input into the aerobic treatment space for aerobic fermentation treatment;

[0062] The oily wastewater after aerobic fermentation treatment in the aerobic treatment space then enters the anaerobic treatment space for anaerobic fermentation treatment;

[0063] S7, Filtration Processing:

[0064] The terminal filter is an activated carbon filter, which can be used to perform the final filtration treatment on the oily wastewater after biological treatment, and completely remove the small amount of oil droplets remaining in the oily wastewater at this time.

[0065] Compared with the prior art, the beneficial effects of the present invention are embodied in the following aspects:

[0066] 1. The invention has a reasonable structural design, high-efficiency oil removal performance, and is equipped with multiple treatment stages. Through multi-stage treatment, it can effectively remove oil droplets of various particle sizes in oily wastewater.

[0067] 2. The present invention has good adaptability and can be used to treat a variety of oils and water qualities. It can effectively treat wastewater containing machinery oil, animal and plant oils, or emulsified oils. It also has good adaptability to various water qualities of pH and salinity and can effectively treat them.

[0068] 3. The present invention has good deep purification performance. Multi-stage treatment can deeply purify oily wastewater, not only removing oil, but also removing pollutants such as suspended matter and partially soluble organic matter in the oily wastewater, which helps to improve the reuse rate of wastewater;

[0069] 4. The cyclone dissolved air flotation mechanism of the present invention can perform step-by-step cyclone dissolved air treatment, so that a large number of microbubbles are precipitated in the oily wastewater in batches. These microbubbles are evenly dispersed in the oily wastewater, and the suspended oil droplets in the oily wastewater can adhere to the microbubbles. Under the action of buoyancy, the microbubbles will float up with the oil droplets and gather on the surface of the oily wastewater, so that the oil droplets in the oily wastewater can be separated more thoroughly.

[0070] 5. In the double membrane separation mechanism of the present invention, when the oily wastewater flows in the slit in the mixed input space, the water phase separation hydrophilic membrane selectively removes the water phase in the oily wastewater, allowing the water phase to pass through the water phase separation hydrophilic membrane and enter the water phase separation space, resulting in an increase in the relative concentration of the oil phase in the oily wastewater in the mixed input space, which further intensifies the collision, coalescence and demulsification between the oil droplets, thereby increasing the permeation flux of the oil phase;

[0071] 6. The auxiliary booster separation mechanism of the present invention can not only force the oily wastewater in the double-membrane separation temporary storage cylinder to flow more smoothly to the mixing input space, but also assist in forcing the suspended oil droplets in the oily wastewater in the double-membrane separation temporary storage cylinder to merge together to form larger oil droplets and gather together to float to the surface of the oily wastewater, thereby assisting in separating part of the oil phase in advance to reduce the workload of the oil phase separation hydrophobic membrane. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 It is a schematic diagram of the overall layout of the present invention;

[0073] Figure 2 It is a structural schematic diagram of the cyclonic dissolved air flotation mechanism of the present invention;

[0074] Figure 3 It is a structural schematic diagram of the double membrane separation mechanism of the present invention;

[0075] Figure 4 It is a schematic structural diagram of the double membrane separation containing cylinder of the present invention;

[0076] Figure 5 It is a structural schematic diagram of the auxiliary boosting piston of the present invention;

[0077] Figure 6 It is a schematic diagram of the structure of the biological treatment mechanism of the present invention;

[0078] Figure 7 It is a schematic structural diagram of the space-divided ring shell of the present invention.

[0079] In the figure, 10-initial sedimentation tank, 11-oil separator, 20-cyclone dissolved air flotation mechanism, 21-flotation treatment tank, 211-flotation wastewater input pipe, 2110-flotation wastewater input control valve, 212-flotation wastewater output pipe, 2120-flotation wastewater output control valve, 213-flotation pressure relief pipe, 2130-flotation pressure relief control valve, 22-air conveying ring shell, 221-air conveying nozzle, 23-flotation oil foam discharge pipe, 230-oil foam discharge control valve, 231-sealed matching sliding hole, 24-pressure reduction control mechanism, 241-pressure reduction control connecting pipe, 2410-pressure reduction control valve, 240-pressure reduction control vacuum tank, 242-vacuum exhaust pipe, 2420-vacuum exhaust control valve, 2 43-decompression control vacuum pump, 25-low speed stirring mechanism, 251-low speed stirring drive shaft, 252-stirring drive connecting rod, 253-low speed stirring drive ring, 254-low speed stirring drive plate, 255-stirring drive housing, 256-low speed stirring drive motor, 26-external discharge lifting mechanism, 261-external discharge lifting fixed cylinder, 262-external discharge lifting sliding cylinder, 263-external discharge lifting drive rod, 30-double membrane separation mechanism, 31-double membrane separation temporary storage cylinder, 311-double membrane separation input pipe, 3110-separation input control valve, 312-floating oil auxiliary external discharge pipe, 3120-auxiliary external discharge control valve, 32-double membrane separation housing cylinder, 321-oil phase separation space, 3210-oil phase separation external pipe, 322-mixing input space, 323-water phase separation space, 3230-water phase separation outer pipe, 33-oil phase separation partition, 330-oil phase separation hydrophobic membrane, 34-water phase separation partition, 340-water phase separation hydrophilic membrane, 35-auxiliary boost separation mechanism, 351-auxiliary boost piston, 3510-forced flow hole, 352-boost piston drive rod, 353-boost drive fixed cylinder, 354-boost drive sliding cylinder, 355-auxiliary boost drive rod, 356-rotating shaft connection hole, 357-opening and closing disk rotating shaft, 358-opening and closing control disk, 3580-forced flow matching hole, 359-opening and closing disk drive motor, 36-double membrane separation back pressure mechanism, 361-back pressure circulation ring shell, 3610-back pressure flow hole, 362-back pressure external exhaust pipe, 3620-separation back pressure control valve, 363-reflux temporary storage tank, 40-biological treatment mechanism, 41-biological treatment outer cylinder shell, 410-aerobic treatment space, 411-aerobic treatment input pipe, 42-biological treatment inner cylinder shell, 421-anaerobic treatment output pipe, 420-anaerobic treatment space, 43-aeration conveying ring shell, 431-aeration conveying nozzle, 432-aeration overflow ventilation pipe, 44-space separation ring shell, 440-treatment exchange filter, 441-treatment exchange through hole, 45-exchange barrier ring shell, 451-treatment exchange matching hole, 452-exchange opening and closing support ring rail, 453-exchange opening and closing drive ring, 50-terminal filter. DETAILED DESCRIPTION

[0080] Combine the following Figure 1 to Figure 7 The present invention is described in detail. For the convenience of description, the directions mentioned below are defined as follows: the up, down, left, right, front, and back directions mentioned below are consistent with the up, down, left, right, front, and back directions of the projection relationship of the respective main views or structural schematic diagrams themselves.

[0081] Embodiment 1:

[0082] A multi-stage modular oily wastewater purification device, such as Figure 1 As shown, it includes an initial sedimentation tank 10, a grease trap 11, a cyclone dissolved air flotation mechanism 20, a double membrane separation mechanism 30, a biological treatment mechanism 40 and a terminal filter 50 which are sequentially connected;

[0083] The initial sedimentation tank 10 is a sedimentation tank of the prior art, and the grease trap 11 is an inclined plate type grease trap of the prior art;

[0084] The output end of the initial sedimentation tank 10 is connected to the input end of the grease trap 11 through a pipeline;

[0085] like Figure 2 As shown, the cyclone dissolved air flotation mechanism 20 includes an air flotation treatment tank 21, a hollow air delivery ring shell 22 is fixed at the bottom of the air flotation treatment tank 21, and a plurality of air delivery nozzles 221 connected to the inside of the air delivery ring shell 22 are fixed at the top of the air delivery ring shell 22;

[0086] The air delivery ring casing 22 is connected to the air delivery pump of the prior art through a pipeline, and the air delivery pump is used to deliver high-pressure air to the inside of the air delivery ring casing 22;

[0087] A flotation wastewater inlet pipe 211 connected to the inside of the flotation treatment tank 21 is fixed to the outside of the flotation treatment tank 21, and a flotation wastewater outlet pipe 212 connected to the inside of the flotation treatment tank 21 is fixed to the bottom of the flotation treatment tank 21;

[0088] The flotation wastewater input pipe 211 is provided with a flotation wastewater input control valve 2110, and the flotation wastewater output pipe 212 is provided with a flotation wastewater output control valve 2120;

[0089] The flotation wastewater input pipe 211 is connected to the output end of the grease trap 11 through a pipeline;

[0090] A flotation pressure relief pipe 213 connected to the inside of the flotation treatment tank 21 is fixed on the top of the flotation treatment tank 21, and a flotation pressure relief control valve 2130 is provided on the flotation pressure relief pipe 213;

[0091] An air flotation oil foam discharge pipe 23 is provided on the top of the air flotation treatment tank 21, and an oil foam discharge control valve 230 is provided on the air flotation oil foam discharge pipe 23;

[0092] like Figure 2As shown, a pressure reducing control mechanism 24 is provided in connection with the flotation treatment tank 21. The pressure reducing control mechanism 24 includes a pressure reducing control vacuum tank 240 connected with the flotation treatment tank 21 through a pressure reducing control connecting pipe 241. The pressure reducing control connecting pipe 241 is provided with a pressure reducing control valve 2410. The pressure reducing control vacuum tank 240 is connected with a pressure reducing control vacuum pump 243 through a vacuum exhaust pipe 242. The vacuum exhaust pipe 242 is provided with a vacuum exhaust control valve 2420.

[0093] like Figure 2 As shown, a low-speed stirring mechanism 25 is provided at the bottom of the air flotation treatment tank 21. The low-speed stirring mechanism 25 includes a low-speed stirring driving shaft 251 which is rotatably connected to the bottom of the air flotation treatment tank 21 and extends vertically. The low-speed stirring driving shaft 251 is fixedly connected to a low-speed stirring driving ring 253 through a plurality of stirring driving connecting rods 252. A plurality of vertically extending low-speed stirring driving plates 254 are fixed to the upper end of the low-speed stirring driving ring 253.

[0094] A stirring drive housing 255 is fixed at the lower end of the air flotation treatment tank 21, and the lower end of the low-speed stirring drive shaft 251 extends into the stirring drive housing 255. A low-speed stirring drive motor 256 for driving the low-speed stirring drive shaft 251 to rotate is fixed in the stirring drive housing 255;

[0095] The low-speed stirring driving motor 256 is a motor of the prior art, and the low-speed stirring driving motor 256 drives the low-speed stirring driving shaft 251 to rotate through gear transmission.

[0096] like Figure 2 As shown, the air-floating oil foam outer discharge pipe 23 is connected to the top of the air-floating treatment tank 21 through the outer discharge lifting mechanism 26. The top of the air-floating treatment tank 21 has a vertically through-going closed matching sliding hole 231. The air-floating oil foam outer discharge pipe 23 is slidably connected in the closed matching sliding hole 231. The outer discharge lifting mechanism 26 includes an outer discharge lifting fixed cylinder 261 fixed to the top of the air-floating treatment tank 21 and opening upward. The outer side of the outer discharge lifting fixed cylinder 261 is slidably connected to an outer discharge lifting sliding cylinder 262 with an opening downward. The outer discharge lifting sliding cylinder 262 is fixedly connected to the air-floating oil foam outer discharge pipe 23.

[0097] An outer row lifting driving rod 263 for driving the outer row lifting sliding cylinder 262 to lift and move is provided in the outer row lifting fixed cylinder 261. The outer row lifting driving rod 263 is an electrically controlled telescopic rod driven by a servo motor in the prior art. The outer rod end of the outer row lifting driving rod 263 is fixedly connected to the bottom of the outer row lifting fixed cylinder 261, and the inner rod end of the outer row lifting driving rod 263 is fixedly connected to the top of the outer row lifting sliding cylinder 262.

[0098] like Figure 3As shown, the double membrane separation mechanism 30 includes a pair of double membrane separation temporary storage cylinders 31 extending vertically, and a horizontally extending double membrane separation receiving cylinder 32 is fixed near the lower end of the double membrane separation temporary storage cylinders 31. Figure 4 As shown, an oil phase separation partition 33 and a water phase separation partition 34 are fixed in the double membrane separation container 32;

[0099] The oil phase separation partition 33 and the water phase separation partition 34 are both arranged perpendicular to the axis of the double membrane separation containing cylinder 32;

[0100] like Figure 4 As shown, both the oil phase separation partition 33 and the water phase separation partition 34 are porous hollow structures with two sides penetrated, and a plurality of oil phase separation hydrophobic membranes 330 are fixed on the side close to each other of the oil phase separation partition 33, and a plurality of water phase separation hydrophilic membranes 340 are fixed on the side close to each other of the water phase separation partition 34;

[0101] The oil phase separation hydrophobic membrane 330 is a selective permeable membrane of the prior art, which only allows the oil phase in the wastewater to pass through. The water phase separation hydrophilic membrane 340 is a selective permeable membrane of the prior art, which only allows the water phase in the wastewater to pass through. The oil phase separation hydrophobic membrane 330 and the water phase separation hydrophilic membrane 340 are both commercially available products, and those skilled in the art can choose them according to actual needs.

[0102] The portion of the double membrane separation container 32 between the oil phase separation partition 33 and the water phase separation partition 34 forms a mixing input space 322, the side of the oil phase separation partition 33 away from the water phase separation partition 34 forms an oil phase separation space 321, and the side of the water phase separation partition 34 away from the oil phase separation partition 33 forms a water phase separation space 323;

[0103] The mixing input space 322 is connected to the interior of the double membrane separation temporary storage cylinder 31 through the mixing input pipe 320;

[0104] like Figure 3 As shown, a double membrane separation input pipe 311 and a floating oil auxiliary external discharge pipe 312 connected to the inside of the double membrane separation temporary storage cylinder 31 are fixed to the outside of the double membrane separation temporary storage cylinder 31, and the floating oil auxiliary external discharge pipe 312 is located above the double membrane separation input pipe 311;

[0105] The double membrane separation input pipe 311 is provided with a separation input control valve 3110, and the floating oil auxiliary external discharge pipe 312 is provided with an auxiliary external discharge control valve 3120;

[0106] The double membrane separation input pipe 311 is connected to the flotation wastewater output pipe 212 through a pipeline;

[0107] An oil phase separation outer discharge pipe 3210 connected to the oil phase separation space 321 is fixed to the outside of the double membrane separation accommodating cylinder 32, and a water phase separation outer discharge pipe 3230 connected to the water phase separation space 323 is fixed to the outside of the double membrane separation accommodating cylinder 32;

[0108] like Figure 6 As shown, the biological treatment mechanism 40 includes a vertically placed biological treatment outer cylinder shell 41, a biological treatment inner cylinder shell 42 coaxially arranged therewith is fixed inside the biological treatment outer cylinder shell 41, an aerobic treatment space 410 is formed between the inner wall of the biological treatment outer cylinder shell 41 and the outer wall of the biological treatment inner cylinder shell 42, and an anaerobic treatment space 420 is formed inside the biological treatment inner cylinder shell 42;

[0109] A plurality of aerobic treatment input pipes 411 connected to the aerobic treatment space 410 are fixed on the outside of the biological treatment outer cylinder shell 41, and an anaerobic treatment output pipe 421 extending vertically and connected to the anaerobic treatment space 420 is fixed on the top of the biological treatment outer cylinder shell 41;

[0110] The anaerobic treatment output pipe 421 is connected to the input end of the terminal filter 50 through a pipeline;

[0111] An aeration conveying ring shell 43 is fixed at the bottom of the aerobic treatment space 410, and a plurality of aeration conveying nozzles 431 connected to the inside of the aeration conveying ring shell 43 are fixed at the top of the aeration conveying ring shell 43;

[0112] An aeration overflow ventilation pipe 432 connected to the aerobic treatment space 410 is fixed on the top of the biological treatment outer cylinder shell 41;

[0113] The aeration conveying ring shell 43 is connected to the air conveying pump of the prior art through a pipeline, and the air conveying pump is used to convey air into the aeration conveying ring shell 43;

[0114] like Figure 7 As shown, a coaxial space separation ring shell 44 is fixed inside the biological treatment outer cylinder shell 41, and the space separation ring shell 44 is arranged outside the biological treatment inner cylinder shell 42. The side wall of the space separation ring shell 44 has a plurality of processing exchange through holes 441 penetrating along the radial direction thereof. A layer of processing exchange filter screen 440 is fixed outside the space separation ring shell 44. An exchange barrier ring shell 45 coaxial with the space separation ring shell 44 is rotatably connected inside the space separation ring shell 44. The side wall of the exchange barrier ring shell 45 has a plurality of processing exchange matching holes 451 penetrating along the radial direction thereof.

[0115] The treatment exchange filter 440 is a commercially available 400-mesh filter of the prior art;

[0116] An exchange opening and closing support ring rail 452 coaxially arranged therewith is fixed to the top of the biological treatment outer cylinder shell 41, and an exchange opening and closing drive ring 453 is rotatably connected to the exchange opening and closing support ring rail 452, and the exchange opening and closing drive ring 453 is fixedly connected to the upper end of the exchange barrier ring shell 45;

[0117] The exchange opening and closing driving ring 453 is driven by a prior art servo motor fixed to the top of the biological treatment outer cylinder shell 41 through gear transmission to rotate around the axis of the exchange opening and closing supporting ring rail 452.

[0118] Embodiment 2:

[0119] This embodiment describes a multi-stage modular oily wastewater purification method, based on a multi-stage modular oily wastewater purification device in the above embodiment 1, comprising the following steps:

[0120] S1. Sedimentation treatment:

[0121] The oily wastewater to be treated is transported to the initial sedimentation tank 10 and allowed to settle for 2 to 6 hours;

[0122] Remove larger suspended solids from oily wastewater;

[0123] S2. Oil separation treatment:

[0124] The oily wastewater after the sedimentation treatment is transported to the grease trap 11 for oil separation treatment at a flow rate of 2 to 5 mm / s;

[0125] Remove larger suspended oil droplets and floating oil droplets from oily wastewater;

[0126] S3, flotation treatment:

[0127] The oily wastewater after oil separation treatment is transported to the inside of the flotation treatment tank 21 through the flotation wastewater input pipe 211, and the input stops when the volume reaches 70%;

[0128] The oily wastewater in the flotation treatment tank 21 is aerated, and high-pressure air is delivered to the inside of the air delivery ring shell 22 by an air delivery pump. The air pressure is set to 1Mpa, and the high-pressure air is discharged through each air delivery nozzle 221 to form microbubbles. The microbubbles flow from bottom to top in the oily wastewater, and the oil droplets can adhere to the microbubbles and float up with the microbubbles to gather on the surface of the oily wastewater;

[0129] At the same time, part of the air will dissolve in the oily wastewater. When the air pressure in the flotation treatment tank 21 reaches 1Mpa, aeration is stopped.

[0130] At this time, the oily wastewater in the flotation treatment tank 21 is in a saturated state with dissolved air;

[0131] Open the oil foam discharge control valve 230 and control its opening degree, so that the oil droplets gathered on the surface of the oily wastewater are discharged through the air flotation oil foam discharge pipe 23 under the high pressure of the air flotation treatment tank 21;

[0132] When the lower end of the air-floating oil foam discharge pipe 23 is provided with a liquid level sensor, it is convenient to control the lower end of the air-floating oil foam discharge pipe 23 to always be in contact with the liquid surface through the discharge lifting mechanism 26. During the discharge of high-pressure air through the air-floating oil foam discharge pipe 23, the oil droplets gathered on the surface of the oily wastewater can be discharged through the air-floating oil foam discharge pipe 23 along with the air flow under the drive of the air flow. When the oil droplets gathered on the surface of the oily wastewater are discharged, the oil foam discharge control valve 230 is closed;

[0133] In the external discharge lifting mechanism 26, the external discharge lifting driving rod 263 is an electrically controlled telescopic rod driven by a servo motor in the prior art. The extension of the inner rod of the external discharge lifting driving rod 263 can drive the external discharge lifting sliding cylinder 262 together with the air-floating oil foam external discharge pipe 23 to move upward. The retraction of the inner rod of the external discharge lifting driving rod 263 can drive the external discharge lifting sliding cylinder 262 together with the air-floating oil foam external discharge pipe 23 to move downward. The signal of the liquid level sensor at the lower end of the air-floating oil foam external discharge pipe 23 will be fed back to limit the driving of the external discharge lifting driving rod 263, so that the lower end of the air-floating oil foam external discharge pipe 23 is always just in contact with the liquid surface.

[0134] S4, Cyclone Dissolved Gas Treatment:

[0135] The inside of the decompression control vacuum tank 240 is evacuated by using the decompression control vacuum pump 243 to make the inside of the decompression control vacuum tank 240 in a vacuum state, and then the vacuum evacuation is stopped and the vacuum exhaust control valve 2420 is closed;

[0136] Then, the pressure reducing control valve 2410 is opened to connect the pressure reducing control vacuum tank 240 with the flotation treatment tank 21 through the pressure reducing control connecting pipe 241. Due to the pressure difference, the high-pressure air in the flotation treatment tank 21 will quickly enter the pressure reducing control vacuum tank 240 through the pressure reducing control connecting pipe 241, so that the air pressure in the pressure reducing control vacuum tank 240 is balanced with the air pressure in the flotation treatment tank 21.

[0137] Under the effect of reduced pressure, a large number of microbubbles will be precipitated from the oily wastewater in the saturated state of dissolved gas. These microbubbles are evenly dispersed in the oily wastewater. The suspended oil droplets in the oily wastewater can adhere to the microbubbles, and under the effect of buoyancy, the microbubbles will float up with the oil droplets and gather on the surface of the oily wastewater.

[0138] At the same time, the low-speed stirring drive motor 256 drives the low-speed stirring drive shaft 251 to rotate through gear transmission, and the low-speed stirring drive shaft 251 drives the low-speed stirring drive ring 253 to rotate together with the multiple low-speed stirring drive plates 254 through the multiple stirring drive connecting rods 252. The multiple low-speed stirring drive plates 254 are used to drive and stir the oily wastewater in the flotation treatment tank 21, so that the oily wastewater as a whole rotates around the vertical axis of the flotation treatment tank 21 to generate a vortex. The rotation speed of the low-speed stirring drive shaft 251 is 30rad / min.

[0139] Since water has a greater density than oil, under the centrifugal effect, the suspended oil droplets in the oily wastewater will be concentrated at the vertical axis of the flotation treatment tank 21. The oil foam discharge control valve 230 is opened and its opening is controlled so that the oil droplets concentrated at the vertical axis of the flotation treatment tank 21 are discharged through the flotation oil foam discharge pipe 23.

[0140] The flotation wastewater output control valve 2120 is opened, and the oily wastewater after the cyclone dissolved air treatment is discharged through the flotation wastewater output pipe 212;

[0141] S5, membrane separation treatment;

[0142] The oily wastewater after the cyclone dissolved gas treatment is input into the double membrane separation temporary storage cylinder 31 arranged in pairs. Under the action of the self-weight pressure, the oily wastewater in the double membrane separation temporary storage cylinder 31 enters the mixing input space 322 through the mixing input pipe 320;

[0143] The distance between the oil phase separation partition 33 and the water phase separation partition 34 is 5 mm;

[0144] The oil phase separation hydrophobic membrane 330 and the water phase separation hydrophilic membrane 340 are both selective permeable membranes of the prior art;

[0145] When the oily wastewater flows in the narrow slit in the mixing input space 322, the water phase separation hydrophilic membrane 340 selectively removes the water phase in the oily wastewater, allowing the water phase to pass through the water phase separation hydrophilic membrane 340 and enter the water phase separation space 323, resulting in an increase in the relative concentration of the oil phase in the oily wastewater in the mixing input space 322, which further intensifies the collision, aggregation and demulsification between the oil droplets, thereby increasing the permeation flux of the oil phase, and the oil phase in the oily wastewater will pass through the oil phase separation hydrophobic membrane 330 and enter the oil phase separation space 321;

[0146] This allows the water phase and the oil phase in the oily wastewater to be separated;

[0147] The oil phase separated from the oily wastewater is discharged through the oil phase separation external discharge pipe 3210, and the water phase separated from the oily wastewater is discharged through the water phase separation external discharge pipe 3230;

[0148] S6. Biological treatment:

[0149] The oily wastewater is input into the aerobic treatment space 410 through a plurality of aerobic treatment input pipes 411 for aerobic fermentation treatment;

[0150] An air delivery pump is used to deliver air to the interior of the aeration delivery ring shell 43, and the air is discharged from each aeration delivery nozzle 431 to provide oxygen dissolution for the oily wastewater in the aerobic treatment space 410;

[0151] The aerobic treatment space 410 contains Pseudomonas multivorans, Pseudomonas aeruginosa, Pseudomonas fluorescens, Flavobacterium brevis, Bacillus subtilis, Bacillus licheniformis, and Bacillus brevis;

[0152] Aerobic fermentation was carried out at 40°C for 72 hours;

[0153] Then, the exchange opening and closing driving ring 453 is driven by the existing servo motor fixed on the top of the biological treatment outer cylinder shell 41 through gear transmission to rotate around the axis of the exchange opening and closing support ring rail 452, and the exchange opening and closing driving ring 453 drives the exchange barrier ring shell 45 to rotate together, so that each treatment exchange matching hole 451 is connected with each treatment exchange through hole 441 in a one-to-one correspondence;

[0154] The oily wastewater in the aerobic treatment space 410 passes through the treatment exchange through hole 441 and the treatment exchange matching hole 451 and enters the anaerobic treatment space 420 for anaerobic fermentation treatment;

[0155] The anaerobic treatment space 420 contains Clostridium acetobutylicum, Clostridium beijerinckii, butyrivibrio, Methanobacterium formicum, Methanobacterium thermoautotrophicum, Methanococcus mazei, and Methanogenic filamentous bacteria of Sordellii;

[0156] Aerobic fermentation was carried out at 40°C for 72 hours;

[0157] The treated oily wastewater is discharged through the anaerobic treatment output pipe 421;

[0158] S7, Filtration Processing:

[0159] The terminal filter 50 is an activated carbon filter, and the terminal filter 50 can be used to perform a final filtration treatment on the oily wastewater after biological treatment, so as to completely remove a small amount of oil droplets remaining in the oily wastewater at this time.

[0160] Embodiment 3:

[0161] On the basis of Example 1, a plurality of decompression control vacuum tanks 240 are provided, and each decompression control vacuum tank 240 is connected to the inside of the flotation treatment tank 21 through an independent decompression control connecting pipe 241, and each decompression control vacuum tank 240 is connected to a decompression control vacuum pump 243 through a separate vacuum exhaust pipe 242;

[0162] The pressure-reducing controlled vacuum pump 243 is a vacuum pump of the prior art.

[0163] Embodiment 4:

[0164] This embodiment describes a multi-stage modular oily wastewater purification method, a multi-stage modular oily wastewater purification device based on the above-mentioned embodiment 3, and the difference from embodiment 2 is that, in step S4, a stepped cyclone dissolved air treatment is performed, and when a decompression control vacuum tank 240 is connected to the flotation treatment tank 21, the decompression control vacuum tank 240 is numbered Z1, Z2, and Z3, and the corresponding decompression control connecting pipe 241 and decompression control valve 2410 are numbered G1, G2, and G3 and F1, F2, and F3 respectively;

[0165] Open the pressure reducing control valve 2410 of number F1 to connect the pressure reducing control vacuum tank 240 of number Z1 with the air flotation treatment tank 21 through the pressure reducing control connecting pipe 241 of number G1. After the air pressure in the pressure reducing control vacuum tank 240 of number Z1 is balanced with the air pressure in the air flotation treatment tank 21, close the pressure reducing control valve 2410 of number F1.

[0166] Next, the pressure reducing control valve 2410 of number F2 is opened to connect the pressure reducing control vacuum tank 240 of number Z2 with the air flotation treatment tank 21 through the pressure reducing control connecting pipe 241 of number G2. After the air pressure in the pressure reducing control vacuum tank 240 of number Z2 is balanced with the air pressure in the air flotation treatment tank 21, the pressure reducing control valve 2410 of number F2 is closed.

[0167] Then, the pressure reducing control valve 2410 of number F3 is opened to connect the pressure reducing control vacuum tank 240 of number Z3 with the air flotation treatment tank 21 through the pressure reducing control connecting pipe 241 of number G3. After the air pressure in the pressure reducing control vacuum tank 240 of number Z3 is balanced with the air pressure in the air flotation treatment tank 21, the pressure reducing control valve 2410 of number F3 is closed.

[0168] The flotation treatment tank 21 is depressurized in a stepwise manner, so that a large number of microbubbles are precipitated in the oily wastewater in batches. These microbubbles are evenly dispersed in the oily wastewater, and the suspended oil droplets in the oily wastewater can adhere to the microbubbles. Under the action of buoyancy, the microbubbles will float up with the oil droplets and gather on the surface of the oily wastewater, so that the oil droplets in the oily wastewater can be separated more thoroughly.

[0169] Embodiment 5:

[0170] On the basis of Example 3, Figure 3As shown, the double membrane separation temporary storage cylinder 31 is provided with an auxiliary boosting separation mechanism 35, which includes an auxiliary boosting piston 351 slidably connected in the double membrane separation temporary storage cylinder 31, and a vertically extending boosting piston driving rod 352 is fixed on the top of the auxiliary boosting piston 351, and the upper end of the boosting piston driving rod 352 extends upward to the outside of the double membrane separation temporary storage cylinder 31;

[0171] A booster drive fixed cylinder 353 with an opening facing upward is fixed on the outside of the double membrane separation temporary storage cylinder 31, a booster drive sliding cylinder 354 is slidably connected inside the booster drive fixed cylinder 353, and the top of the booster drive sliding cylinder 354 is fixedly connected to the upper end of the booster piston drive rod 352;

[0172] An auxiliary boost drive rod 355 for driving the boost drive sliding cylinder 354 to rise and fall is provided in the boost drive fixed cylinder 353. The auxiliary boost drive rod 355 is an electrically controlled telescopic rod driven by a servo motor in the prior art. The outer rod end of the auxiliary boost drive rod 355 is fixedly connected to the bottom of the boost drive fixed cylinder 353, and the inner rod end of the auxiliary boost drive rod 355 is fixedly connected to the top of the boost drive sliding cylinder 354.

[0173] like Figure 5 As shown, the auxiliary boosting piston 351 has a plurality of forced circulation holes 3510 extending parallel to its axis, the lower end of the auxiliary boosting piston 351 has a shaft connecting hole 356 with an opening facing downward, the shaft connecting hole 356 is rotatably connected with an opening and closing disk shaft 357, the lower end of the opening and closing disk shaft 357 is fixed with an opening and closing control disk 358, the top of the opening and closing control disk 358 is in pressure contact with the lower end of the auxiliary boosting piston 351, and the opening and closing control disk 358 has a plurality of forced circulation matching holes 3580 extending parallel to the axis of the auxiliary boosting piston 351;

[0174] A shutter disk drive motor 359 for driving the shutter disk shaft 357 to rotate is fixed in the shaft connecting hole 356. The shutter disk drive motor 359 is a servo motor in the prior art. The output shaft of the shutter disk drive motor 359 drives the shutter disk shaft 357 to rotate through a planetary reducer in the prior art.

[0175] Embodiment 6:

[0176] This embodiment describes a multi-stage modular oily wastewater purification method, which is a multi-stage modular oily wastewater purification device based on the above-mentioned embodiment 5. The difference from embodiment 4 is that in step S5, the auxiliary booster separation mechanism 35 is used to drive the oily wastewater in the double membrane separation temporary storage cylinder 31 to flow to the mixing input space 322;

[0177] The inner rod of the auxiliary boost driving rod 355 is retracted to drive the boost driving sliding cylinder 354, together with the boost piston driving rod 352 and the auxiliary boost piston 351, to move downward, and the auxiliary boost piston 351 is used to compress the volume of the double membrane separation temporary storage cylinder 31, forcing the oily wastewater in the double membrane separation temporary storage cylinder 31 to flow more smoothly to the mixing input space 322;

[0178] The output shaft of the opening and closing disk driving motor 359 drives the opening and closing disk rotating shaft 357 to rotate through the planetary reducer of the prior art, and the opening and closing disk rotating shaft 357 drives the opening and closing control disk 358 to rotate, and controls each forced flow matching hole 3580 to be connected with each forced flow hole 3510 in a one-to-one correspondence, or controls each forced flow matching hole 3580 to be staggered and isolated from each forced flow hole 3510;

[0179] When the auxiliary boosting piston 351 moves downward, each forced flow matching hole 3580 and each forced flow hole 3510 are in a mutually dislocated and isolated state. When the auxiliary boosting piston 351 moves upward and returns to its original position, each forced flow matching hole 3580 and each forced flow hole 3510 are in a connected state.

[0180] The auxiliary boosting piston 351 is driven to move back and forth in the double-membrane separation temporary storage cylinder 31. During the process of the auxiliary boosting piston 351 moving upward and returning to its original position, the newly input oily wastewater can also be forced to pass through the forced flow matching hole 3580 and the forced flow hole 3510, which helps the suspended oil droplets in the oily wastewater to merge together to form larger oil droplets and gather together to float to the surface of the oily wastewater. The double-membrane separation temporary storage cylinder 31 is provided with a liquid level sensor of the prior art, and the feedback control input to the surface of the oily wastewater in the double-membrane separation temporary storage cylinder 31 always just covers the floating oil auxiliary external discharge pipe 312. The floating oil auxiliary external discharge pipe 312 is opened to discharge the oil droplets gathered on the surface of the oily wastewater to reduce the workload of the oil phase separation hydrophobic membrane 330.

[0181] Embodiment 7:

[0182] On the basis of Example 5, Figure 4 As shown, a double membrane separation back pressure mechanism 36 is provided outside the double membrane separation accommodating cylinder 32, and the double membrane separation back pressure mechanism 36 includes a back pressure circulation ring shell 361 fixed to the outside of the double membrane separation accommodating cylinder 32, and the mixing input space 322 is connected to the inside of the back pressure circulation ring shell 361 through a plurality of back pressure circulation holes 3610;

[0183] A back pressure outer discharge pipe 362 connected to the inner part of the back pressure circulation ring shell 361 is fixed on the outer side thereof, and a separation back pressure control valve 3620 is provided on the back pressure outer discharge pipe 362. The separation back pressure control valve 3620 is an electric regulating valve driven and controlled by a servo motor in the prior art.

[0184] The aerobic treatment input pipe 411 is connected to the reflux temporary storage tank 363 through a pipeline;

[0185] The other end of the back pressure external discharge pipe 362 is connected to a reflux temporary storage tank 363, in which a delivery pump of prior art is provided, and the delivery pump is used to deliver the wastewater temporarily stored in the reflux temporary storage tank 363 to the double membrane separation temporary storage cylinder 31 for reflux treatment.

[0186] Embodiment 8:

[0187] This embodiment describes a multi-stage modular oily wastewater purification method, which is a multi-stage modular oily wastewater purification device based on the above-mentioned embodiment 7, and is different from embodiment 6 in that, in step S5, during the oily wastewater circulation in the mixed input space 322, part of the oily wastewater enters the back pressure circulation ring shell 361 through the back pressure circulation hole 3610, and the opening of the separation back pressure control valve 3620 is controlled so that the flow rate flowing into the back pressure circulation ring shell 361 is 20% of the flow rate input into the mixed input space 322;

[0188] The oily wastewater in the back pressure circulation ring shell 361 enters the reflux temporary storage tank 363 through the back pressure external discharge pipe 362, and the wastewater temporarily stored in the reflux temporary storage tank 363 is re-transported to the double membrane separation temporary storage cylinder 31 for reflux treatment. The amount of circulating reflux treatment is 20% of the total amount input into the double membrane separation temporary storage cylinder 31.

[0189] In step S6, the oily wastewater discharged from the back pressure external discharge pipe 362 is input into the aerobic treatment space 410 through a plurality of aerobic treatment input pipes 411 for aerobic fermentation treatment.

Claims

1. A multi-stage modular oily wastewater purification device, characterized in that: It comprises an initial sedimentation tank (10), a grease trap (11), a cyclonic dissolved air flotation mechanism (20), a double membrane separation mechanism (30), a biological treatment mechanism (40) and a terminal filter (50) which are sequentially connected; The cyclone dissolved air flotation mechanism (20) comprises an air flotation treatment tank (21), a hollow air delivery ring shell (22) is fixed at the bottom of the air flotation treatment tank (21), and a plurality of air delivery nozzles (221) connected to the inside of the air delivery ring shell (22) are fixed at the top of the air delivery ring shell (22); The top of the air flotation treatment tank (21) is provided with an air flotation oil foam discharge pipe (23), and the air flotation oil foam discharge pipe (23) is provided with an oil foam discharge control valve (230); The double membrane separation mechanism (30) comprises a pair of double membrane separation temporary storage cylinders (31) arranged vertically, a horizontally extending double membrane separation accommodating cylinder (32) is fixed between the double membrane separation temporary storage cylinders (31) near the lower end, and an oil phase separation partition (33) and a water phase separation partition (34) are fixed inside the double membrane separation accommodating cylinder (32); The oil phase separation partition (33) is fixed with a plurality of oil phase separation hydrophobic membranes (330), and the water phase separation partition (34) is fixed with a plurality of water phase separation hydrophilic membranes (340); The portion of the double-membrane separation container (32) between the oil phase separation partition (33) and the water phase separation partition (34) forms a mixing input space (322), the side of the oil phase separation partition (33) away from the water phase separation partition (34) forms an oil phase oil phase separation space (321), and the side of the water phase separation partition (34) away from the oil phase separation partition (33) forms a water phase separation space (323); The mixing input space (322) is connected to the interior of the double membrane separation temporary storage cylinder (31) through a mixing input pipe (320); The biological treatment mechanism (40) comprises a vertically placed biological treatment outer cylinder shell (41), a biological treatment inner cylinder shell (42) coaxially arranged therewith is fixed inside the biological treatment outer cylinder shell (41), an aerobic treatment space (410) is formed between the inner side wall of the biological treatment outer cylinder shell (41) and the outer side wall of the biological treatment inner cylinder shell (42), and an anaerobic treatment space (420) is formed inside the biological treatment inner cylinder shell (42); An aeration and conveying ring shell (43) is fixed at the bottom of the aerobic treatment space (410), and a plurality of aeration and conveying nozzles (431) connected to the interior of the aeration and conveying ring shell (43) are fixed at the top of the aeration and conveying ring shell (43).

2. A multi-stage modular oily wastewater purification equipment according to claim 1, characterized in that: A pressure reducing control mechanism (24) is provided in connection with the flotation treatment tank (21), the pressure reducing control mechanism (24) comprising a pressure reducing control vacuum tank (240) connected to the flotation treatment tank (21) via a pressure reducing control connecting pipe (241), the pressure reducing control connecting pipe (241) having a pressure reducing control valve (2410), the pressure reducing control vacuum tank (240) being connected to a pressure reducing control vacuum pump (243) via a vacuum exhaust pipe (242), the vacuum exhaust pipe (242) having a vacuum exhaust control valve (2420).

3. A multi-stage modular oily wastewater purification equipment according to claim 2, characterized in that: There are multiple decompression control vacuum tanks (240), and each of the decompression control vacuum tanks (240) is connected to the interior of the flotation treatment tank (21) via an independent decompression control connecting pipe (241), and each of the decompression control vacuum tanks (240) is connected to a decompression control vacuum pump (243) via a separate vacuum exhaust pipe (242).

4. The multi-stage modular oily wastewater purification equipment according to claim 2, characterized in that: A low-speed stirring mechanism (25) is provided at the bottom of the air flotation treatment tank (21), and the low-speed stirring mechanism (25) comprises a low-speed stirring drive shaft (251) rotatably connected to the bottom of the air flotation treatment tank (21) and extending vertically, the low-speed stirring drive shaft (251) is fixedly connected to a low-speed stirring drive ring (253) through a plurality of stirring drive connecting rods (252), and a plurality of vertically extending low-speed stirring drive plates (254) are fixed to the upper end of the low-speed stirring drive ring (253); A stirring drive housing (255) is fixed at the lower end of the flotation treatment tank (21), the lower end of the low-speed stirring drive shaft (251) extends into the interior of the stirring drive housing (255), and a low-speed stirring drive motor (256) for driving the low-speed stirring drive shaft (251) to rotate is fixed in the stirring drive housing (255).

5. The multi-stage modular oily wastewater purification equipment according to claim 1, characterized in that: The air-floating oil foam external discharge pipe (23) is connected to the top of the air-floating treatment tank (21) through an external discharge lifting mechanism (26); the top of the air-floating treatment tank (21) has a vertically through-going sealed matching sliding hole (231); the air-floating oil foam external discharge pipe (23) is slidably connected in the sealed matching sliding hole (231); the external discharge lifting mechanism (26) comprises an external discharge lifting fixed cylinder (261) fixed to the top of the air-floating treatment tank (21) and opening upward; an external discharge lifting sliding cylinder (262) opening downward is slidably connected to the outer side of the external discharge lifting fixed cylinder (261); the external discharge lifting sliding cylinder (262) is fixedly connected to the air-floating oil foam external discharge pipe (23); An outer row lifting driving rod (263) for driving the outer row lifting sliding cylinder (262) to move upward and downward is arranged inside the outer row lifting fixed cylinder (261).

6. The multi-stage modular oily wastewater purification equipment according to claim 1, characterized in that: A flotation pressure relief pipe (213) connected to the interior of the flotation treatment tank (21) is fixed on the top of the flotation treatment tank (21), and the flotation pressure relief pipe (213) is provided with a flotation pressure relief control valve (2130).

7. The multi-stage modular oily wastewater purification equipment according to claim 1, characterized in that: The double membrane separation temporary storage cylinder (31) is provided with an auxiliary boosting separation mechanism (35), the auxiliary boosting separation mechanism (35) comprising an auxiliary boosting piston (351) slidably connected in the double membrane separation temporary storage cylinder (31), a vertically extending boosting piston driving rod (352) being fixed to the top of the auxiliary boosting piston (351), and the upper end of the boosting piston driving rod (352) extending upward to the outside of the double membrane separation temporary storage cylinder (31); A boost drive fixed cylinder (353) with an upward opening is fixed on the outside of the double membrane separation temporary storage cylinder (31), a boost drive sliding cylinder (354) is slidably connected inside the boost drive fixed cylinder (353), and the top of the boost drive sliding cylinder (354) is fixedly connected to the upper end of the boost piston drive rod (352); An auxiliary boost drive rod (355) for driving the boost drive sliding cylinder (354) to move up and down is arranged in the boost drive fixed cylinder (353).

8. The multi-stage modular oily wastewater purification equipment according to claim 7, characterized in that: The auxiliary boosting piston (351) has a plurality of forced circulation holes (3510) extending parallel to its axis, the lower end of the auxiliary boosting piston (351) has a shaft connection hole (356) with an opening facing downward, the shaft connection hole (356) is rotatably connected with an opening and closing disk shaft (357), the lower end of the opening and closing disk shaft (357) is fixed with an opening and closing control disk (358), the top of the opening and closing control disk (358) is in press contact with the lower end of the auxiliary boosting piston (351), and the opening and closing control disk (358) has a plurality of forced circulation matching holes (3580) extending parallel to the axis of the auxiliary boosting piston (351); A shutter disk driving motor (359) for driving the shutter disk rotating shaft (357) to rotate is fixed in the rotating shaft connecting hole (356).

9. The multi-stage modular oily wastewater purification equipment according to claim 1, characterized in that: A double membrane separation back pressure mechanism (36) is provided outside the double membrane separation containing cylinder (32), and the double membrane separation back pressure mechanism (36) comprises a back pressure circulation annular shell (361) fixed outside the double membrane separation containing cylinder (32), and the mixing input space (322) is connected to the inside of the back pressure circulation annular shell (361) through a plurality of back pressure circulation holes (3610); A back pressure external discharge pipe (362) connected to the interior of the back pressure circulation ring shell (361) is fixed on the outside of the back pressure circulation ring shell (361), and a separation back pressure control valve (3620) is provided on the back pressure external discharge pipe (362); The other end of the back pressure external discharge pipe (362) is connected to a reflux temporary storage tank (363).

10. A multi-stage modular oily wastewater purification method, based on the multi-stage modular oily wastewater purification equipment according to claim 4, characterized in that: The following steps are involved: S1. Sedimentation treatment: The oily wastewater to be treated is transported to an initial sedimentation tank (10) and allowed to settle for 2 to 6 hours; S2. Oil separation treatment: The oily wastewater after the sedimentation treatment is transported to a grease trap (11) for oil separation treatment at a flow rate of 2 to 5 mm / s; S3, flotation treatment: The oily wastewater after the oil separation treatment is transported to the interior of the flotation treatment tank (21), and the input is stopped after 70% of the volume is filled; Aerating the oily wastewater in the flotation treatment tank (21), using an air delivery pump to deliver high-pressure air to the inside of the air delivery ring shell (22), the air pressure being set to 1 MPa, the high-pressure air being discharged through each air delivery nozzle (221) to form microbubbles, the microbubbles flowing from bottom to top in the oily wastewater, the oil droplets being able to adhere to the microbubbles and float up with the microbubbles and gather on the surface of the oily wastewater; At the same time, part of the air will dissolve in the oily wastewater. When the air pressure in the flotation treatment tank (21) reaches 1Mpa, aeration is stopped. At this time, the oily wastewater in the flotation treatment tank (21) is in a state of dissolved gas saturation; Opening the oil foam discharge control valve (230) and controlling its opening degree, so that the oil droplets accumulated on the surface of the oily wastewater are discharged through the flotation oil foam discharge pipe (23) under the high pressure of the flotation treatment tank (21); When a liquid level sensor is provided at the lower end of the air-floating oil foam discharge pipe (23), the lower end of the air-floating oil foam discharge pipe (23) is controlled to always be in contact with the liquid level. When high-pressure air is discharged through the air-floating oil foam discharge pipe (23), oil droplets gathered on the surface of the oily wastewater can be discharged through the air-floating oil foam discharge pipe (23) along with the air flow under the drive of the air flow. When the oil droplets gathered on the surface of the oily wastewater are discharged, the oil foam discharge control valve (230) is closed; S4, Cyclone Dissolved Gas Treatment: Under the decompression effect of the decompression control mechanism (24), a large number of microbubbles will be precipitated from the oily wastewater in the saturated state of dissolved gas. These microbubbles are evenly dispersed and filled in the oily wastewater. The suspended oil droplets in the oily wastewater can adhere to the microbubbles, and under the effect of buoyancy, the microbubbles will float up with the oil droplets and gather on the surface of the oily wastewater. At the same time, the low-speed stirring mechanism (25) drives and stirs the oily wastewater in the air flotation treatment tank (21), so that the oily wastewater as a whole rotates around the vertical axis of the air flotation treatment tank (21) to generate a vortex; Since water has a greater density than oil, under the centrifugal effect, the suspended oil droplets in the oily wastewater will be concentrated at the vertical axis of the flotation treatment tank (21), and the oil foam discharge control valve (230) is opened and its opening is controlled so that the oil droplets concentrated at the vertical axis of the flotation treatment tank (21) are discharged through the flotation oil foam discharge pipe (23); The flotation wastewater output control valve (2120) is opened, and the oily wastewater after the cyclone gas dissolution treatment is discharged through the flotation wastewater output pipe (212); S5, membrane separation treatment; The oily wastewater after the cyclonic dissolved gas treatment is input into the double membrane separation temporary storage cylinder (31) arranged in pairs. Under the action of the deadweight pressure, the oily wastewater in the double membrane separation temporary storage cylinder (31) enters the mixing input space (322) through the mixing input pipe (320); The distance between the oil phase separation partition (33) and the water phase separation partition (34) is 5 mm; When the oily wastewater flows in the narrow slit in the mixing input space (322), the water phase separation hydrophilic membrane (340) selectively removes the water phase in the oily wastewater, allowing the water phase to pass through the water phase separation hydrophilic membrane (340) and enter the water phase separation space (323), resulting in an increase in the relative concentration of the oil phase in the oily wastewater in the mixing input space (322), which further intensifies the collision, aggregation and demulsification between the oil droplets, thereby increasing the permeation flux of the oil phase, and the oil phase in the oily wastewater will pass through the oil phase separation hydrophobic membrane (330) and enter the oil phase separation space (321); This allows the water phase and the oil phase in the oily wastewater to be separated; S6. Biological treatment: The oily wastewater is then input into the aerobic treatment space (410) for aerobic fermentation treatment; The oily wastewater after aerobic fermentation treatment in the aerobic treatment space (410) enters the anaerobic treatment space (420) for anaerobic fermentation treatment; S7, Filtration Processing: The terminal filter (50) is an activated carbon filter, and the terminal filter (50) is used to perform a final filtration treatment on the oily wastewater after the biological treatment, so as to completely remove a small amount of oil droplets remaining in the oily wastewater at this time.

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