A green and low-carbon garbage leachate concentrate treatment system and method

Abstract

The present invention relates to a treatment system for a green and low-carbon landfill leachate concentrate, comprising a flocculation sedimentation tank, a sand filter and an ozone advanced oxidation device connected in sequence; the landfill leachate concentrate first enters the flocculation sedimentation tank, and after flocculation and sedimentation by adding drugs, the supernatant enters the sand filter, and the effluent of the sand filter enters the ozone advanced oxidation device for treatment and discharge; the ozone advanced oxidation device comprises an oxidation reaction tower, an atomizing spray device is provided in the tower, and a film-forming catalytic device is provided below the atomizing spray device; the atomizing spray device sprays the incoming water downward in the form of mist droplets, and reacts with the continuous phase ozone, and the film-forming catalytic device comprises a plurality of catalytic rods, and the surface of each catalytic rod is covered with an ozone catalyst coating, and the falling water droplets form a liquid film on the catalytic rod and are further catalytically degraded. The present invention uses a continuous ozone gas phase to contact with a discontinuous wastewater droplet phase, improves the gas-liquid mass transfer coefficient and oxidation efficiency, and improves the ozone utilization rate and oxidation effect.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental protection, and in particular to a system and method for processing green and low-carbon garbage leachate concentrate. Background Art

[0002] A large amount of leachate will be generated during the landfill, incineration, and other treatment processes of domestic waste. The current treatment of leachate generally adopts a technical model of front-end biochemical and back-end double membrane treatment. A certain amount of concentrate (nanofiltration concentrate and reverse osmosis concentrate) will be generated during the back-end treatment process. This part of the concentrate needs to be further treated. However, the concentrate of leachate is still a polluted wastewater with high salt content, high organic content, and difficult to degrade. It is difficult to treat with biochemical and ordinary physical and chemical methods, and has become a major problem in the current waste disposal process. Under standard conditions, ozone has a high oxidation potential (2.07V) and is a common oxidant. In addition, after ozone decomposes in water, it produces stronger oxidizing substances than ozone, such as hydroxyl radicals (·OH), which can effectively remove organic pollutants in water. As a non-selective strong oxidant, the hydroxyl radical (·OH) has an oxidation potential of 2.8V and a reaction rate constant of up to 10 for the oxidation reaction with organic molecules. 6 -10 9 L·mol -1 ·s -1 Many organic pollutants that are difficult to biodegrade can be effectively removed by the oxidation of OH. Although ozone advanced oxidation technology is widely used and has advantages such as easy application, no secondary pollution, and good oxidation effect; however, in practical application, there are still technical problems such as low ozone utilization rate and poor wastewater oxidation effect.

[0003] The reaction between ozone gas and pollutants in wastewater belongs to a gas-liquid two-phase reaction system. At present, bubbling reaction towers (bubbling reaction tanks) and packed reactors are the two main types of ozone oxidation reactors. These reactors mainly control the size of ozone gas bubbles and select suitable packings to promote gas-liquid mass transfer and reaction effects. However, due to the defect that the mass transfer rate of pollutants in the continuous liquid phase is not high, there is limited room for further improvement in the reaction efficiency of existing reactors. It is necessary to explore new reaction contact methods in the hope of achieving a breakthrough in the mass transfer rate, and on this basis, develop new high-efficiency reactors to further exert the ozone oxidation efficiency, which will be of key significance to the improvement of the treatment effect of the entire landfill leachate treatment process. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a green and low-carbon garbage leachate concentrate treatment system and method, which includes an ozone advanced oxidation device, which improves the gas-liquid mass transfer coefficient and the oxidation efficiency of ozone on organic matter by changing the gas-liquid contact mode, thereby solving the technical problem of poor oxidation effect of ozone oxidation on garbage leachate in the prior art.

[0006] (II) Technical solution

[0007] In a first aspect, the present invention provides a green and low-carbon landfill leachate concentrate treatment system, which comprises a flocculation sedimentation tank, a sand filter and an ozone advanced oxidation device connected in sequence; the landfill leachate concentrate first enters the flocculation sedimentation tank, and after flocculation and sedimentation by adding a drug, the supernatant enters the sand filter, and the effluent of the sand filter enters the ozone advanced oxidation device for treatment and then is discharged;

[0008] The ozone advanced oxidation device comprises an oxidation reaction tower; at least one group of film-forming catalytic devices is arranged in the oxidation reaction tower, and a group of atomizing spray devices is arranged above each group of film-forming catalytic devices at a certain distance; a gas-liquid separation device is arranged near the top of the oxidation reaction tower; the top of the oxidation reaction tower is connected to a gas recovery pipeline, and the gas recovery pipeline passes the ozone recovered from the top of the tower into the ozone inlet at the bottom of the tower; a water collection tank is also arranged at the bottom of the oxidation reaction tower, and a water outlet pipe is arranged in the water collection tank, and the water outlet pipe is connected to a circulation main pipe and an external drainage pipe, and the circulation main pipe is connected to a plurality of groups of circulation branch pipes, and each group of circulation branch pipes is respectively connected to a group of the atomizing spray devices; the circulation main pipe is also connected to the water inlet; the position of the ozone inlet in the oxidation reaction tower is higher than the liquid level of the water collection tank and lower than the bottom film-forming catalytic device;

[0009] Among them, the atomizing spray device is used to spray the wastewater to be treated with ozone downward in the form of mist droplets; the film-forming catalytic device comprises a plurality of catalytic rods, each of which is covered with an ozone catalyst coating; the plurality of catalytic rods are arranged to form the film-forming catalytic device.

[0010] According to a preferred embodiment of the present invention, the atomizing spray device comprises a plurality of atomizing nozzles, which are solid conical nozzles and can process wastewater into droplets with a diameter of 100-1000 μm; the cross-section of the catalytic rod is circular, elliptical, gourd-shaped or droplet-shaped, and the equivalent diameter of each catalytic rod is 1-5 cm; the cross-section of the catalytic rod is elliptical, and the major axis direction of the cross-section is arranged along the vertical direction.

[0011] According to a preferred embodiment of the present invention, the catalytic rods of the biofilm catalytic device are arranged in two or more layers and have a layer spacing; the single-layer catalytic rods are arranged in parallel and a rod spacing is formed between the two catalytic rods; the catalytic rods of two adjacent layers are arranged in a staggered manner so that the catalytic rods of one layer are exactly located within the rod spacing of the catalytic rods of the other layer; or the catalytic rods of two adjacent layers are arranged in a cross-arrangement so that the catalytic rods of one layer are exactly crossed with the catalytic rods of the other layer. The crossing angle is not limited, preferably 15-90 degrees, more preferably 45-90 degrees.

[0012] According to a preferred embodiment of the present invention, three groups of biofilm catalytic devices and three groups of atomizing spray devices are arranged from bottom to top in the oxidation reaction tower; each catalytic rod of the biofilm catalytic device is mounted and fixed on a mounting bracket on the inner wall of the oxidation reaction tower. Preferably, the vertical distance between the topmost catalytic rod of a single group of biofilm catalytic devices and the lower edge of the atomizing nozzle of a group of atomizing spray devices corresponding thereto is 15cm-30cm; the single-layer catalytic rods are arranged in parallel and the rod spacing between the two catalytic rods is 3-10 times (preferably 4 times) the diameter of the catalytic rod; the interlayer spacing between the two layers of catalytic rods is 1-3 catalyst rod diameters. Preferably, the catalytic rods are made of stainless steel or plastic, and the ozone catalyst coating on their surface is MnO 2 .

[0013] According to a preferred embodiment of the present invention, a group of micro-bubbling reaction components is also provided between at least one group of atomizing spray devices and the film-forming catalytic device, and the micro-bubbling reaction component includes a porous support net installed on the inner wall of the oxidation reaction tower, and a bubbling tube is arranged on the porous support net, and the two ends of the bubbling tube are expanded and the middle is set as a throat; the upper end opening of the bubbling tube faces the atomizing nozzle of the atomizing spray device, and the lower end opening faces the film-forming catalytic device; the inner wall of the bubbling tube is coated with an organic matter capture coating and an ozone catalytic coating; the two coatings are arranged alternately in the form of spots, and the bubbling tubes are hollowed out. The ozone introduced from the bottom of the oxidation reaction tower reaches the bottom of the atomizing nozzle from the hollow position to form an ozone continuous phase, and the inside of the bubbling tube forms an enhanced oxidation place. Preferably, the upper end of the bubbling tube is 5-10cm away from the lower edge of the atomizing nozzle of the atomizing spray device, and the lower edge is 1-4cm away from the upper edge of the uppermost catalytic rod of the single group of film-forming catalytic device; the throat diameter of the bubbling tube is between 0.5-3cm, and the throat length is 5-20cm.

[0014] According to a preferred embodiment of the present invention, each group of circulation branch pipes comprises two or more circulation branch pipes, and each circulation branch pipe is connected to at least three atomizing nozzles. Preferably, the flow rate of a single atomizing nozzle is 10-30L / min (preferably 20L / min), and the operating pressure is 0.5-1bar (preferably 0.7bar). Preferably, each group of circulation branch pipes comprises two circulation branch pipes, which are arranged in parallel, and each circulation branch pipe is provided with 3 atomizing nozzles, which are distributed along the width direction of the oxidation reaction tower.

[0015] According to a preferred embodiment of the present invention, the gas-liquid separation device is composed of a group of obliquely installed corrugated plates, the spacing between adjacent corrugated plates is 1-10 mm, preferably 1.5-3 mm; the corrugated plates are coated with an ozone catalyst coating. Preferably, the corrugated plates are made of plastic or stainless steel, and the ozone catalyst coating on the surface is MnO 2 The ozone catalyst coating on the surface of the corrugated plate has ozone catalytic effect and hydrophilic effect, which improves the gas-water separation effect and organic matter degradation efficiency.

[0016] According to a preferred embodiment of the present invention, the distance from the bottom of the gas-liquid separation device to the upper edge of the atomizing nozzle of the uppermost atomizing spray device is 10-15 cm, and the distance from the top of the gas-liquid separation device to the top of the oxidation reaction tower is 25-30 cm.

[0017] According to a preferred embodiment of the present invention, the ozone advanced oxidation device also includes an ozone generator, which is located outside the oxidation reaction tower; an ozone online detector is provided on the gas recovery pipeline; the ozone online detector is connected to a controller of the ozone generator; when the ozone online detector detects that the ozone concentration in the gas recovery pipeline is insufficient, the ozone generator is controlled to start to replenish new ozone into the oxidation reaction tower.

[0018] According to a preferred embodiment of the present invention, an exhaust fan and a compressor are connected to the gas recovery pipeline, and the ozone online detector is located at the front end of the compressor. The exhaust fan is used to extract the ozone gas collected at the top of the oxidation reaction tower, and then pass it through the ozone inlet at the bottom of the oxidation reaction tower after being processed by the compressor; the ozone generator passes ozone into the oxidation reaction tower through a breathable pipe or merges with the gas compressed by the compressor and passes it into the oxidation reaction tower together. In addition, an ozone online detector can also be set in the middle of the tower body of the oxidation reaction tower. The ozone online detector is connected to the controller of the ozone generator. When it is detected that the ozone concentration in the oxidation reaction tower is insufficient, the ozone generator is controlled to start to add new ozone to the oxidation reaction tower.

[0019] According to a preferred embodiment of the present invention, the outlet pipe is connected to the circulation main pipe and the external drainage pipe by a three-way pipe, the circulation main pipe is connected to the water inlet, the water inlet continuously passes the wastewater to be treated, and the external drainage pipe continuously discharges the treated wastewater; a part of the water in the water collection tank is mixed with the water inlet through the circulation main pipe and sprayed into the oxidation reaction tower through the circulation branch pipe and the atomizing spray device, and the other part of the water in the water collection tank is discharged through the external drainage pipe.

[0020] Among them, a pressure gauge is provided on the circulation main pipe, and an independent control valve is provided at the connection between the circulation main pipe and each group of circulation branch pipes, thereby automatically controlling the operation of all or part of the atomizing spray devices in the oxidation reaction tower according to the water quality of the wastewater to be treated (mainly the COD of the influent).

[0021] According to a preferred embodiment of the present invention, a pressure reducing valve and a pressure gauge are provided on the top of the oxidation reaction tower, and the pressure reducing valve is used to release the pressure when the pressure of the oxidation reaction tower exceeds a set value.

[0022] According to a preferred embodiment of the present invention, the oxidation reaction tower shell is made of plastic, stainless steel or fiberglass; or the oxidation reaction tower shell is a concrete structure. Preferably, the bottom of the oxidation reaction tower is a conical bottom to form the water collection trough.

[0023] In a second aspect, the present invention provides a method for treating green and low-carbon landfill leachate concentrate, which comprises using the above system to treat the landfill leachate concentrate, including:

[0024] The concentrated liquid of the landfill leachate is subjected to flocculation sedimentation, sand filtration and ozone advanced oxidation treatment; the concentrated liquid of the landfill leachate first enters the flocculation sedimentation tank, and after flocculation and sedimentation by adding drugs, the supernatant enters the sand filter, and the effluent of the sand filter enters the ozone advanced oxidation device for treatment before discharge;

[0025] Wherein, the pH value of the wastewater entering the oxidation reaction tower is adjusted to 6.0-7.0, and the ozone concentration in the oxidation reaction tower is controlled to be 5-10 mg / L, preferably 5 mg / L, 6 mg / L, 7 mg / L, 8 mg / L, 9 mg / L or 10 mg / L; the pressure in the oxidation reaction tower is 0.1 mPa-1.0 mPa; preferably 0.1 mPa, 0.2 mPa, 0.3 mPa, 0.4 mPa, 0.5 mPa or 1.0 mPa.

[0026] Moderately increasing the pressure inside the oxidation reaction tower can effectively increase the rate of the degradation reaction. When the pressure exceeds the standard, the pressure reducing valve at the top of the oxidation reaction tower is used to reduce the pressure to maintain the safe operation of the oxidation reaction tower.

[0027] (III) Beneficial effects

[0028] The technical effects of the present invention are as follows:

[0029] 1. The commonly used gas-liquid contact method is: ozone gas is bubbled into the wastewater, the wastewater liquid phase is the continuous phase and the ozone gas is the discontinuous phase. The present invention changes the traditional gas-liquid contact method of ozone oxidation by setting an atomizing spray device and introducing ozone at the bottom of the tower. Compared with the existing bubbling reaction tower (bubbling reaction tank) and packing reactor, the present invention changes the traditional gas-liquid contact method of ozone oxidation, sets ozone as the continuous phase and wastewater as the discontinuous phase, and uses an atomizing spray device to disperse the wastewater into small particles (small droplets) and disperse them in the continuous ozone gas; through dispersion measures, the particle size of the wastewater particles is reduced, the diffusion path of the pollutant molecules in the liquid phase to the gas-liquid interface is shortened, and the apparent mass transfer rate on the liquid film side of the gas-liquid interface is increased. Although compared with the current traditional gas-liquid contact method, the side diffusion path of ozone is to be larger as a whole, but because the molecular diffusion rate in the gas phase is much greater than the molecular diffusion rate in the liquid phase, the gas-liquid apparent mass transfer rate of the oxidation process of the present invention will be significantly improved compared with the traditional gas-liquid contact method. The present invention uses the gas phase as the continuous phase and at the same time minimizes the particle size of the wastewater particles (reducing the path length of the pollutant molecules in the liquid phase to diffuse to the gas-liquid interface), greatly improving the gas-liquid mass transfer coefficient and the gas-liquid interface area, thereby increasing the contact probability between ozone molecules and pollutants in the liquid phase, and ultimately achieving the goal of increasing the oxidation reaction rate.

[0030] 2. The present invention further provides a film-forming catalytic device below the atomizing spray device. The film-forming catalytic device is composed of a number of catalytic rods with ozone catalytic coatings on their surfaces. The curved surfaces of the catalytic rods are used to allow liquid droplets to adhere to the surfaces of the catalytic rods to form a spreading liquid film, thereby shortening the diffusion path of ozone molecules to the organic molecules in the liquid film. The ozone catalyst coating (MnO2) on the surface of the catalytic rods is used to catalytically degrade the organic molecules in the wastewater, thereby improving the catalytic efficiency and facilitating the degradation of difficult-to-degrade organic molecules.

[0031] The present invention further increases the mass transfer rate of ozone molecules and their solubility in aqueous solution by setting the gas concentration of ozone in the oxidation reaction tower and the gas pressure intensity in the oxidation reaction tower, thereby increasing the oxidation reaction rate.

[0032] 3. Furthermore, the present invention provides a gas-liquid separation device in the oxidation reaction tower, which is composed of a group of corrugated plates arranged at an angle and intervals, and an ozone catalyst coating is provided on the corrugated plates; the hydrophilicity of the ozone catalyst coating is utilized to make the wastewater adhere to the surface and merge into large droplets, thereby achieving effective separation of gas and liquid, and circulating the recovered ozone from the bottom of the oxidation reaction tower to achieve efficient utilization of ozone and avoid ozone waste. During the ozone recovery process, the ozone concentration in the recovery pipeline is monitored, and when the concentration drops, the ozone generator can be turned on to supplement new ozone gas to maintain the concentration and pressure of the ozone gas in the oxidation reaction tower.

[0033] 4. Further, the present invention is also provided with a group of micro-bubbling reaction components in the atomizing spray device and the film-forming catalytic device, which can slow down the speed of the wastewater moving downward, and the atomizing spray device sprays fine droplets (100-1000 μm), and the droplets react with the ozone of the continuous phase, wherein the organic matter is partially degraded, and the undegraded organic matter and the droplets fall into the bubbling tube together; the ozone gas molecules moving upward from the bottom of the bubbling tube meet and bubble with the wastewater moving downward in the throat, and the degradation of organic matter is enhanced under the catalytic action of the ozone catalytic coating; for some organic matter with larger molecules that are difficult to degrade, the flow rate of the wastewater is greatly slowed down when passing through the throat, so that the organic matter with larger molecules is adsorbed by the organic matter capture coating in the throat, and enhanced degradation occurs under the action of ozone bubbling for a long time. The present invention combines two mass transfer modes such as continuous gas phase ozone / fog wastewater and micro-bubbling, which greatly improves the ozone utilization efficiency and the degradation effect of ozone on organic matter in wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The present invention is a process flow chart of a green and low-carbon landfill leachate concentrate.

[0035] Figure 2 This is a schematic diagram of the overall structure of the ozone advanced oxidation device of Example 1.

[0036] Figure 3 This is a schematic diagram of the film-forming catalytic device and the circulation branch pipe in the ozone advanced oxidation device of Example 1.

[0037] Figure 4 This is a schematic diagram of the circulation branch pipe in the ozone advanced oxidation device of Example 1.

[0038] Figure 5 This is a schematic diagram of the structure of the ozone advanced oxidation device of Example 2. DETAILED DESCRIPTION

[0039] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation modes in conjunction with the accompanying drawings.

[0040] Example 1

[0041] like Figure 1 The figure shows a process flow chart of a green and low-carbon landfill leachate concentrate of the present invention. The landfill leachate concentrate comes from the concentrate obtained by the front-end biochemical and back-end double membrane treatment, including nanofiltration concentrate and reverse osmosis concentrate. First, the landfill leachate concentrate enters the flocculation sedimentation tank, and after flocculation and sedimentation by adding drugs, the supernatant enters the sand filter, and the effluent of the sand filter enters the ozone advanced oxidation device, and meets the external discharge standard after advanced oxidation treatment.

[0042] Combination Figure 2As shown, it is a schematic diagram of an ozone advanced oxidation device of a preferred embodiment of the present invention, wherein the ozone advanced oxidation device includes an oxidation reaction tower, which is a rectangular parallelepiped as a whole (it can also be set as a cylindrical shape), and the bottom is a four-sided cone to form a water collection trough (it can also be set as a cone). The height of the water collection trough is 0.5m, and the cone angle of the water collection trough is 90 degrees. The total height of the oxidation reaction tower body is set to 3.5m, the length is 1.5m, and the width is 1m. The oxidation reaction tower is closed as a whole, and a pressure reducing valve 9 and a pressure gauge 11-1 are installed on the top of the tower body. The material of the oxidation reaction tower is plastic (in other embodiments, it can be stainless steel or concrete). The oxidation reaction tower is provided with three groups of film-forming catalytic devices 2, and the three groups of film-forming catalytic devices 2 are arranged at intervals in the height direction. Atomizing spray devices 1 are arranged at a certain distance above each group of film-forming catalytic devices 2, and a total of three groups of atomizing spray devices 1 are arranged in the oxidation reaction tower. The atomizing spray device 1 comprises a plurality of atomizing nozzles 101. The flow rate of a single atomizing nozzle 101 is 20 L / min, the operating pressure is 0.7 bar, and the atomizing nozzle 101 is a solid conical nozzle, which can process wastewater into droplets with a diameter of 100-1000 μm.

[0043] The atomizing spray device 1 is connected to a circulation branch pipe located outside the oxidation reaction tower, the circulation branch pipe is connected to the circulation main pipe, the lower end of the circulation main pipe is connected to a three-way valve 4, one end of the three-way valve 4 is connected to an external drainage pipe 41, and the other end is connected to a water outlet pipe 42 of the oxidation reaction tower, and a circulation pump 3 is provided on the water outlet pipe 42, and the water outlet pipe 42 is connected to the water outlet of the water collection tank at the bottom of the oxidation reaction tower. Among them, the water outlet pipe 42, the external drainage pipe 41, the circulation pump 3, the circulation main pipe, the circulation branch pipe, etc. constitute the wastewater inlet and outlet and circulation device. The circulation main pipe is also connected to the inlet water to be treated, so that the inlet water and the circulating water at the bottom of the oxidation reaction tower are combined and transported to the atomizing spray device 1 through the circulation branch pipe. A pressure gauge 11-2 is provided on the circulation main pipe, and a separate control valve is provided at the connection between the circulation main pipe and each group of circulation branches. These control valves can be used to adjust the number of groups of atomizing spray devices 1 working in the oxidation reaction tower. The outlet pipe 42 is connected to the circulation main pipe and the external drainage pipe 41 by a three-way valve 4. The circulation main pipe is connected to the water inlet, and the water inlet continuously passes the wastewater to be treated, and the external drainage pipe 41 continuously discharges the treated wastewater. A part of the water in the water collection tank of the oxidation reaction tower is mixed with the water inlet through the circulation main pipe and the circulation branch pipe and the atomizing spray device 1, and the other part of the water in the water collection tank is discharged through the external drainage pipe 41, thus forming a continuous water inlet / outlet ozone advanced oxidation.

[0044] The biofilm catalytic device 2 includes a plurality of catalytic rods 21, the cross-section of which is circular, elliptical, gourd-shaped or drop-shaped. If the cross-section of the catalytic rod is elliptical, the long axis direction of the cross-section is arranged along the vertical direction. Figure 3As shown, in this embodiment, the cross section of the catalyst rod 21 is a circle with a diameter of 5 cm. The catalyst rods 21 in each biofilm catalytic device 2 are distributed in multiple layers, and each layer includes a plurality of dry catalyst rods 21, which are made of stainless steel. Figure 3 As shown, the top layer has 5 rods, the second layer has 6 rods, and the third layer has 5 rods. The single-layer catalyst rods are evenly arranged, and the rod spacing is about 4 times the catalyst rod diameter; the catalyst rods 21 between adjacent layers are staggered, and the layer spacing is 2 times the catalyst rod diameter. Staggered arrangement means that Figure 3 As shown, one layer of catalyst rods is just located within the rod spacing of another layer of catalyst rods. A layer of MnO is coated on the surface of the catalyst rod 21. 2 , the coating has ozone catalytic activity. The catalytic rod 21 is mounted and fixed on the mounting bracket 10 on the inner wall of the oxidation reaction tower. In the oxidation reaction tower of this embodiment, three groups of catalytic rods are arranged, and each group of catalytic rods constitutes a film-forming catalytic device 2. The distance between the topmost catalytic rod of the film-forming catalytic device 2 and the lower edge of its upper atomizing nozzle 101 is 18 cm. The droplets sprayed by the atomizing spray device 1 will slide along the curved surface of the catalytic rod 21 during the falling process, and form a layer of liquid film on the surface of the catalytic rod 21. The liquid film is in contact with the continuous ozone gas, and because the surface of the catalytic rod 21 has MnO 2 , which can catalyze the oxidation rate and oxidation intensity of ozone on organic matter in wastewater.

[0045] Combination Figure 4 As shown, since the number of the atomizing spray device 1 is 3, the number of the circulating branch pipes in this embodiment is also 3, and each group of circulating branch pipes includes 2 circulating branch pipes, and each circulating branch pipe is provided with 3 atomizing nozzles 101. The 3 groups of circulating branch pipes are arranged at intervals in height, each group of circulating branch pipes includes 2 circulating branch pipes, and 3 atomizing nozzles 101 are installed on one circulating branch pipe, and 6 atomizing nozzles 101 constitute an atomizing spray device 1. In this embodiment, the number of atomizing nozzles 101 is 18. Each group of circulating branch pipes is provided with an independent valve, which can adjust the water inlet flow of each circulating branch pipe respectively.

[0046] A gas-liquid separation device 6 is provided near the top of the oxidation reaction tower. The gas-liquid separation device 6 is composed of a group of inclined corrugated plates. The corrugated plates are made of plastic, and the gap between two adjacent corrugated plates is 2 mm. Figure 2 As shown, the corrugated plate is installed in a manner such that the corrugated extension direction of the corrugated plate is consistent with the inclination direction of the corrugated plate. A layer of catalyst material is coated on the corrugated plate, and the catalyst is MnO 2 The distance from the bottom of the gas-liquid separation device 6 to the upper edge of the uppermost atomizing nozzle 101 is 10 cm, and the distance from the top of the gas-liquid separation device 6 to the top of the oxidation reaction tower is 25 cm.

[0047] A gas recovery pipeline 71 is provided at the top of the oxidation reaction tower and above the gas-liquid separation device 6. An exhaust fan 7 is provided on the gas recovery pipeline 71 for recycling the ozone collected at the top of the oxidation reaction tower. A compressor 8 is connected to the lower part of the gas recovery pipeline 71, and the recovered ozone is pressurized and concentrated and then fed back to the ozone inlet 81 at the bottom of the oxidation reaction tower, and then passed into the oxidation reaction tower through the ozone inlet 81. The position of the ozone inlet 81 in the oxidation reaction tower is higher than the liquid level of the water collection tank and lower than the film-hanging catalytic device 2 at the bottom. An ozone online detector 12 is also provided on the gas recovery pipeline 71 and at the front end of the compressor 8, which is used to detect the ozone concentration in the gas recovery pipeline 71. When the ozone concentration is low, new ozone needs to be added to the oxidation reaction tower.

[0048] Specifically, an ozone generator 5 is also provided outside the oxidation reaction tower, which is connected to the bottom of the oxidation reaction tower through a vent pipe 51. The position of the vent pipe 51 inside the oxidation reaction tower is between the liquid level of the water collection tank and the catalytic film hanging device 2 at the bottom. The ozone online detector 12 signal on the gas recovery pipeline 71 is connected to the controller of the ozone generator 5. The controller calculates the amount of fresh ozone to be supplemented according to the detection value (concentration) of the ozone online detector 12, the volume of the oxidation reaction tower and the set ozone concentration value, etc., and controls the ozone generator 5 to work and generate the required amount of ozone according to the calculation result. The generated ozone is sent to the inside of the oxidation reaction tower through the vent pipe 51, or the generated new ozone can be connected to the gas recovery pipeline 71, and the new ozone and the recovered ozone are combined and compressed together through the compressor 8, and then introduced into the oxidation reaction tower from the ozone inlet 81 after the concentration is increased.

[0049] The processing process of the ozone advanced oxidation device of this embodiment is as follows:

[0050] The pH value of the effluent from the sand filter is adjusted to between 6.0 and 7.0, and the effluent is connected to the circulating main pipe and merged with the circulating wastewater from the water collection tank, and enters the oxidation reaction tower through the circulating branch pipe, and is dispersed into tiny droplets with a diameter of 100-1000 μm by the atomizing spray device 1. Under the dual effects of its own gravity and the rising gas, the droplets show a downward trend as a whole. During the descent, the droplets first contact with the continuous ozone atmosphere, and the pollutants in the droplets react with the ozone molecules and the derived hydroxyl radicals to achieve degradation; at the same time, a large number of droplets will adhere to the surface of each catalyst rod 21 of the catalytic film device 2 during the descent to form a thin liquid film, and the pollutants and ozone molecules in the liquid film react with the ozone catalyst MnO on the surface of the catalyst rod 21. 2Contact, further oxidation occurs under the catalytic action of the catalyst, and further degradation of pollutants is achieved. The droplets eventually fall into the water collection tank at the bottom of the oxidation reaction tower, and are circulated and sprayed into water mist and oxidized by ozone under the action of the circulation pump 3. The outlet pipe 4 is connected to the circulation pump 3, and the outlet end of the circulation pump 3 is connected to the three-way valve 4, the three-way valve 4 is connected to the circulation main pipe, the circulation main pipe is also connected to the water inlet, and the three-way valve 4 is also connected to the external drainage pipe 41. The inlet water is continuously input with water adjusted to pH 6.0-7.0, and the external drainage pipe 41 is continuously discharged. Part of the water in the water collection tank is discharged, and part of it is diluted with the inlet water and then sprayed into the oxidation reaction tower by the circulation branch pipe and the atomizing spray device 1 as mist droplets.

[0051] The ozone gas generated by the ozone generator 5 is introduced from the bottom of the oxidation reaction tower. The ozone introduction flow rate is adjustable. The ozone starts to rise from the bottom of the oxidation reaction tower. During the rising process, it contacts the wastewater droplets and the liquid film on the surface of the catalyst rod 21. The pollutants in the wastewater react with the ozone molecules and derivative oxides such as hydroxyl radicals to achieve organic degradation. The gas will entrain some droplets during the rising process. The gas entrained with droplets finally passes through the gas-liquid separation device 6 to achieve gas-liquid separation. The separated water phase flows back down along the surface of the corrugated plate. The gas continues to rise. The refluxed liquid wastewater contacts the catalyst MnO on the surface of the corrugated plate. 2 and ozone, further oxidation occurs to degrade organic matter.

[0052] The ozone-containing gas separated from the top of the oxidation reaction tower re-enters the bottom of the oxidation reaction tower through the gas recovery pipeline 71, exhaust fan 7 and compressor 8, etc., to achieve the recycling of ozone gas and improve the utilization rate of ozone. The flow rate specification of exhaust fan 7 and compressor 8 is 10m 3 / min. An ozone online detector 12 is installed on the gas recovery pipeline 71. The ozone online detector 12 is located at the front end of the compressor 8 to monitor the concentration of the recovered ozone in real time. The ozone online detector 12 is also connected to the controller of the ozone generator 5. According to the detected ozone concentration, the start and stop of the ozone generator 5 is controlled in real time to maintain the ozone gas inside the oxidation reaction tower at a set level, such as 5mg / L-10mg / L. During the operation of the oxidation reaction tower, excess gas is discharged through the pressure reducing valve 9 at the top of the oxidation reaction tower to maintain the gas pressure inside the oxidation reaction tower at 0.1mPa-1.0mPa.

[0053] Compared with the conventional bubbling ozone oxidation reaction with wastewater as the continuous phase and ozone as the dispersed phase, the present embodiment uses ozone as the continuous phase and wastewater as the dispersed phase, and a film catalytic device 2 composed of an array of catalytic rods 21 is provided, and a gas-liquid-solid three-phase reaction system is formed inside the oxidation reaction tower.

[0054] The ozone advanced oxidation device of this embodiment can achieve efficient degradation of pollutants in wastewater. The present invention processes wastewater into tiny droplets through the atomizing spray device 1, reduces the mass transfer path of pollutants in the liquid phase, increases the area of ​​the gas-liquid contact interface, and increases the probability of ozone molecules and their oxidized derivatives contacting pollutants, thereby increasing the gas-liquid apparent mass transfer rate. Each catalytic rod 21 of the film-forming catalytic device 2 plays a heterogeneous catalytic role in the pollutant degradation reaction. The surface of the catalytic rod 21 can provide a larger gas-liquid contact surface, increasing the gas-liquid mass transfer rate and reaction rate. Finally, the gas-liquid separation device 6 can not only achieve gas-liquid separation, but also the MnO 2 It is not only hydrophilic, but also can provide wastewater droplets with attachment and convergence into large droplets, improve gas-liquid separation efficiency, and can further utilize the catalyst on its surface to catalyze the degradation of attached wastewater and pollutants. During the operation of the ozone advanced oxidation device, the pressure inside the oxidation reaction tower is appropriately increased (such as 0.1mPa-1.0mPa), which can further improve the rate of degradation reaction. By using gas recovery pipelines and components such as exhaust fans and compressors, the utilization rate of ozone can be improved and ozone waste can be avoided. By arranging an ozone online detector 12 on the gas recovery pipeline and automatically linking it with the ozone generator 5 to control it, the cost of ozone preparation can be saved, and a higher ozone concentration can be maintained in the oxidation reaction tower, and the ozone concentration can be maintained within the set value range to ensure the degradation effect of organic matter in wastewater.

[0055] Example 2

[0056] This embodiment is a further improvement of the ozone advanced oxidation device based on the embodiment 1. Figure 5 As shown, a group of micro-bubbling reaction components 13 is also provided between the two groups of atomizing spray devices 1 and the film-forming catalytic device 2 at the bottom. The micro-bubbling reaction component 13 includes a porous support net 131 installed on the inner wall of the oxidation reaction tower, and a bubbling tube 132 is installed in some holes of the porous support net. Corresponding to the number of atomizing nozzles 101, 6 bubbling tubes are arranged on each layer, and the two ends of the bubbling tube 132 are expanded and the middle is set as a throat. The upper end opening of the bubbling tube faces the atomizing nozzle 101 of the atomizing spray device 1, and the lower end opening faces the film-forming catalytic device 2. The inner wall of the bubbling tube 132 is coated with an organic matter capture coating and an ozone catalytic coating, and the two coatings are alternately arranged in the form of spots. The bubbling tubes 132 and the bubbling tubes 132 are hollowed out, so that ozone can move from the bottom to the side of the atomizing spray device 1. The ozone introduced from the bottom of the oxidation reaction tower reaches the bottom of the atomizing nozzle 101 from the hollow position to form an ozone continuous phase, and the inside of the bubbling tube 132 forms an enhanced oxidation place. The upper end of the bubbling tube 132 is 5 cm away from the lower edge of the atomizing nozzle 101 of the atomizing spray device, and the lower edge is 2 cm away from the upper edge of the top catalyst rod of the single group of film-forming catalytic device; the diameter of the throat of the bubbling tube is 2 cm, and the length of the throat is 7 cm. The ozone catalytic coating can be MnO 2The organic matter capture coating can be a hydrophobic silane coupling agent (aminopropyltriethoxysilane, APTES) coating; the silane coupling agent is 0.5-1cm 2 The irregular spots are sprayed on MnO 2 The exposed surfaces of the two coatings account for about 50% of the inner wall surface of the bubble tube 132. The hydrophilic end of the silane coupling agent is connected to the MnO 2 The hydrophobic groups of the silane coupling agent are connected at one end facing outward, and they can capture organic molecules in the water, so that the organic molecules in the wastewater are retained. In this embodiment, by setting a micro-bubbling reaction component 13, the contact mode of the continuous ozone gas phase with the discontinuous wastewater is organically combined with the traditional bubbling reaction contact mode, so as to prevent the difficult-to-degrade organic molecules from falling quickly to the sink with the water droplets. The inner wall of the bubbling tube 132 is coated with an organic capture coating to retain the difficult-to-degrade organic matter, which can further improve the degradation rate of organic matter in the wastewater after one cycle. The ozone advanced oxidation device of this embodiment can reduce the COD of the wastewater to the set value in a shorter time.

[0057] Application Example 1

[0058] The reverse osmosis concentrate of landfill leachate was treated by the system of Example 1, and the water quality conditions entering the ozone advanced oxidation device were: CODcr, 450 mg / L; NH 4 -N (ammonia nitrogen) 15mg / L; salt 15g / L.

[0059] Set the treatment conditions as follows: water flow rate 2m 3 / h, adjust its pH value to 6.5; ozone generator gas flow rate 20L / min, ozone concentration 5mg / L, control wastewater circulation flow rate 20m 3 / h, circulating gas flow rate 5m 3 / min, and control the ozone concentration in the oxidation reaction tower to be 10 mg / L. Use the ozone advanced oxidation device in Example 1 for continuous oxidation degradation treatment, and control the gas pressure inside the oxidation reaction tower to be 0.1mPa, 0.2mPa, 0.4mPa, 0.5mPa, and 1.0mPa. Under different pressure conditions, the effluent was sampled and tested respectively. It was run continuously for 1 month, and the average value was taken after sampling once a day.

[0060] Table 1: CODcr test values ​​of advanced oxidation effluent under different gas pressures

[0061] Reaction pressure / mPa 0.1 0.2 0.4 0.5 1.0 Outlet CODcr / mg / L 70 58 48 43 40

[0062] As can be seen from Table 1, the effluent CODcr achieves a good removal effect, and the effluent CODcr can meet the first-level standard of the "Integrated Sewage Discharge Standard" (GB 8978-1996); when the reaction tower pressure is controlled to be greater than 0.4mPa, the effluent CODcr can meet the first-level A standard of the "Pollutant Discharge Standard for Urban Sewage Treatment Plants" (GB 18918-2002).

[0063] Application Example 2

[0064] On the basis of Application Example 1, the ozone advanced oxidation device in Example 2 was used for continuous oxidation degradation treatment, and the gas pressure inside the oxidation reaction tower was controlled to be 0.1mPa, 0.2mPa, 0.4mPa, 0.5mPa, and 1.0mPa. The inlet water quality and the set treatment conditions were the same as those in Application Example 1. Under different pressure conditions, the outlet water was sampled and tested respectively. It was continuously operated for 1 month, and the average value was taken by sampling once a day for testing.

[0065] Table 2: CODcr test values ​​of advanced oxidation effluent under different gas pressures

[0066] Reaction pressure / mPa 0.1 0.2 0.4 0.5 1.0 Outlet CODcr / mg / L 67 55 44 40 36

[0067] As can be seen from Table 2, the effluent CODcr achieves a good removal effect, and the effluent CODcr can meet the first-level standard of the "Integrated Sewage Discharge Standard" (GB 8978-1996); when the reaction tower pressure is controlled to be greater than 0.4mPa, the effluent CODcr can meet the first-level A standard of the "Pollutant Discharge Standard for Urban Sewage Treatment Plants" (GB 18918-2002).

[0068] Application Example 3

[0069] The reverse osmosis concentrate of landfill leachate was treated by the system of Example 1, and the water quality conditions entering the ozone advanced oxidation device were: CODcr, 450 mg / L; NH 4 -N (ammonia nitrogen) 15mg / L; salt 15g / L.

[0070] Set the treatment conditions as follows: water flow rate 2m 3 / h, adjust its pH value to 6.5; ozone generator gas flow rate 20L / min, control wastewater circulation flow rate 20m 3 / h, circulating gas flow rate 5m 3 / min, and the pressure in the oxidation reaction tower was controlled to be 0.5mPa. The ozone advanced oxidation device in Example 1 was used for continuous oxidation degradation treatment, and the ozone concentration in the oxidation reaction tower was controlled to be 5mg / L, 7.5mg / L, and 10mg / L. Under different ozone concentration conditions, the effluent was sampled and tested respectively. After continuous operation for 1 month, the average value was taken after sampling once a day.

[0071] Table 3: CODcr test values ​​of advanced oxidation effluent at different ozone concentrations

[0072] Ozone concentration in the reaction tower mg / L 5 7.5 10 Outlet CODcr / mg / L 75 49 45

[0073] As can be seen from Table 3, the effluent CODcr achieves a good removal effect, and the effluent CODcr can meet the first-level standard of the "Integrated Sewage Discharge Standard" (GB 8978-1996); when the ozone concentration in the control reaction tower is greater than 7.5 mg / L, the effluent CODcr can meet the first-level A standard of the "Pollutant Discharge Standard for Urban Sewage Treatment Plants" (GB 18918-2002).

[0074] In summary, the ozone advanced oxidation device of the present invention has the advantages of high mass transfer efficiency, high ozone recycling rate, and accurate control of the concentration of each phase in the reaction system and reaction conditions, thereby achieving efficient treatment of wastewater containing organic matter, and has the characteristics of being green, low-carbon and environmentally friendly.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A green and low-carbon landfill leachate concentrate treatment system, characterized in that: It includes a flocculation sedimentation tank, a sand filter and an ozone advanced oxidation device connected in sequence; the concentrated liquid of the landfill leachate first enters the flocculation sedimentation tank, and after flocculation and sedimentation by adding drugs, the supernatant enters the sand filter, and the effluent of the sand filter enters the ozone advanced oxidation device for treatment and then is discharged; The ozone advanced oxidation device comprises an oxidation reaction tower; at least one group of film-forming catalytic devices is arranged in the oxidation reaction tower, and a group of atomizing spray devices is arranged above each group of film-forming catalytic devices at a certain distance; a gas-liquid separation device is arranged near the top of the oxidation reaction tower; the top of the oxidation reaction tower is connected to a gas recovery pipeline, and the gas recovery pipeline passes the ozone recovered from the top of the tower into the ozone inlet at the bottom of the tower; a water collection tank is also arranged at the bottom of the oxidation reaction tower, and a water outlet pipe is arranged in the water collection tank, and the water outlet pipe is connected to a circulation main pipe and an external drainage pipe, and the circulation main pipe is connected to a plurality of groups of circulation branch pipes, and each group of circulation branch pipes is respectively connected to a group of the atomizing spray devices; the circulation main pipe is also connected to the water inlet; the position of the ozone inlet in the oxidation reaction tower is higher than the liquid level of the water collection tank and lower than the bottom film-forming catalytic device; Among them, the atomizing spray device is used to spray the wastewater to be treated with ozone downward in the form of mist droplets; the film-forming catalytic device comprises a plurality of catalytic rods, each of which is coated with an ozone catalyst coating; the plurality of catalytic rods are arranged to form the film-forming catalytic device; A group of micro-bubbling reaction components is also arranged between at least one group of atomizing spray devices and the biofilm catalytic device; the micro-bubbling reaction component comprises a porous support net installed on the inner wall of the oxidation reaction tower, a bubbling tube is arranged on the porous support net, both ends of the bubbling tube are expanded and the middle is arranged as a throat; the upper end opening of the bubbling tube faces the atomizing nozzle of the atomizing spray device, and the lower end opening faces the biofilm catalytic device; the inner wall of the bubbling tube is coated with an organic matter capturing coating and an ozone catalytic coating; the two coatings are arranged alternately in the form of spots, and the space between the bubbling tubes is hollow; the throat diameter of the bubbling tube is 0.5-3cm, and the throat length is 5-20cm.

2. The processing system according to claim 1, characterized in that The atomizing spray device comprises an atomizing nozzle, which is a solid conical nozzle and can process wastewater into droplets with a diameter of 100-1000 μm; the cross-section of the catalyst rod is circular, elliptical, gourd-shaped or droplet-shaped, and the equivalent diameter of each catalyst rod is 1-5 cm; the catalyst rod with an elliptical cross-section has its major axis arranged in the vertical direction.

3. The processing system according to claim 1 or 2, characterized in that: The catalytic rods of the biofilm catalytic device are arranged in two or more layers and have an interlayer spacing; the single-layer catalytic rods are arranged in parallel and a rod spacing is formed between the two catalytic rods; the catalytic rods of two adjacent layers are arranged in a staggered manner so that the catalytic rods of one layer are exactly located within the rod spacing of the catalytic rods of the other layer; or the catalytic rods of two adjacent layers are arranged in a cross-direction so that the catalytic rods of one layer are exactly crossed with the catalytic rods of the other layer.

4. The processing system according to claim 3, characterized in that Three groups of biofilm catalytic devices and three groups of atomizing spray devices are arranged from bottom to top in the oxidation reaction tower; the catalytic rods of the biofilm catalytic devices are fixed on the mounting brackets on the inner wall of the oxidation reaction tower; the vertical distance between the topmost catalytic rod of a single group of biofilm catalytic devices and the lower edge of the atomizing nozzle of a group of atomizing spray devices corresponding thereto is 15cm-30cm; the single-layer catalytic rods are arranged in parallel and the rod spacing between the two catalytic rods is 3-10 times of the diameter of the catalytic rods; the interlayer spacing between the two layers of catalytic rods is 1-3 diameters of the catalytic rods.

5. The processing system according to claim 3, characterized in that Each group of circulation branch pipes includes two or more circulation branch pipes, each circulation branch pipe is connected to at least three atomizing nozzles; the flow rate of a single atomizing nozzle is 10-30L / min, and the operating pressure is 0.5-1bar; the atomizing nozzles are distributed along the width direction of the oxidation reaction tower.

6. The processing system according to claim 1, characterized in that The gas-liquid separation device is composed of a group of obliquely installed corrugated plates, the spacing between adjacent corrugated plates is 1-10 mm, and the corrugated plates are coated with an ozone catalyst coating.

7. The processing system according to claim 1, characterized in that The ozone advanced oxidation device also includes an ozone generator, which is located outside the oxidation reaction tower; an ozone online detector on the gas recovery pipeline; the ozone online detector is connected to the controller of the ozone generator; when the ozone online detector detects that the ozone concentration in the gas recovery pipeline is insufficient, the ozone generator is controlled to be turned on to replenish new ozone into the oxidation reaction tower; or an ozone online detector is arranged in the middle of the tower body of the oxidation reaction tower, the ozone online detector is connected to the controller of the ozone generator, and when it is detected that the ozone concentration in the oxidation reaction tower is insufficient, the ozone generator is controlled to be turned on to replenish new ozone into the oxidation reaction tower.

8. The processing system according to claim 1, characterized in that The outlet pipe is connected to the circulation main pipe and the external drainage pipe by a three-way pipe. The circulation main pipe is connected to the water inlet, and the water inlet continuously passes the wastewater to be treated, and the external drainage pipe continuously discharges the treated wastewater. A part of the water in the water collection tank is mixed with the water inlet through the circulation main pipe and sprayed into the oxidation reaction tower through the circulation branch pipe and the atomizing spray device, and the other part of the water in the water collection tank is discharged through the external drainage pipe.

9. A method for treating green and low-carbon landfill leachate concentrate, characterized in that: The landfill leachate concentrate is treated by using the treatment system according to any one of claims 1 to 8, the treatment method comprising: The concentrated liquid of the landfill leachate is subjected to flocculation sedimentation, sand filtration and ozone advanced oxidation treatment; the concentrated liquid of the landfill leachate first enters the flocculation sedimentation tank, and after flocculation and sedimentation by adding drugs, the supernatant enters the sand filter, and the effluent of the sand filter enters the ozone advanced oxidation device for treatment and then discharged; wherein, the pH value of the wastewater entering the oxidation reaction tower is adjusted to 6.0-7.0, the ozone concentration in the oxidation reaction tower is controlled to 5-10 mg / L, and the pressure in the oxidation reaction tower is 0.1 mPa-1.0 mPa.

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