A single-stage reaction system based on ozone recycling and multi-point dosing

Abstract

This invention discloses a single-stage reaction system based on multi-point ozone recycling and addition, relating to the field of wastewater treatment technology. It includes a reaction tower, an influent system, an ozone addition system, an ozone recycling system, and an effluent system. The reaction tower is internally divided into sequentially connected ozone recycling zone, buffer zone, catalytic oxidation zone, and effluent zone from bottom to top. The influent system transports wastewater to the ozone recycling zone of the reaction tower. The ozone addition system adds ozone to the buffer zone of the reaction tower. The ozone recycling system collects ozone tail gas from the effluent zone and residual ozone in the effluent and re-adds it to the ozone recycling zone of the reaction tower. The effluent system is connected to the effluent zone and discharges the treated wastewater. Thus, by coupling ozone direct oxidation and catalytic oxidation processes in a single-stage reaction tower configuration, the total degradation efficiency is maintained while reducing catalyst usage and ozone dosage, achieving optimization of both equipment investment and operating costs.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a single-stage reaction system based on ozone recycling and multi-point dosing. Background Technology

[0002] Industrial wastewater contains a wide variety of industrial raw materials, intermediates, and metabolites, resulting in complex organic compositions, high toxicity, and poor biodegradability, posing potential risks to the ecological environment and human health. Ozone-based advanced oxidation technologies offer advantages such as strong oxidation capacity, low secondary pollution, convenient preparation and management, and decolorization and deodorization functions, making them highly regarded and widely used in the field of industrial wastewater treatment.

[0003] Currently, ozone processes on the market are divided into two main categories: ozone contact oxidation and ozone catalytic oxidation. Ozone contact oxidation directly utilizes ozone to degrade organic matter in wastewater; ozone catalytic oxidation degrades organic matter by catalyzing ozone to produce more potent oxidizing agents. In industrial wastewater, some organic compounds (such as unsaturated hydrocarbons) can be directly oxidized and degraded by ozone, while others (such as long-chain alkanes and polycyclic aromatic hydrocarbons) require degradation by more potent oxidizing agents (such as ·OH). The proportion of organic components in industrial wastewater that can be directly oxidized by ozone is closely related to the industrial raw materials and production processes. Wastewater treated with advanced oxidation processes is mostly organic wastewater that cannot be degraded by conventional pretreatment processes. For this type of wastewater, ozone contact oxidation alone is convenient to operate and maintain and has low investment, but due to the selective oxidation of ozone, the removal limit of the process is limited by the proportion of organic components that can be directly oxidized by ozone, resulting in limited removal capacity. Ozone catalytic oxidation alone can improve the system's degradation efficiency of organic matter by generating more oxidizing active substances through catalysis of ozone, but due to the low efficiency of catalyst activation of ozone and the high cost of catalysts, the investment and operating costs of the process are high.

[0004] Furthermore, in engineering applications, both ozone contact oxidation and ozone catalytic oxidation processes suffer from high residual ozone concentrations in the effluent due to ozone's low solubility in water, and also generate ozone tail gas. To prevent residual ozone from impacting subsequent treatment processes and the environment, engineering projects require ozone buffer tanks for the self-decay of residual ozone in the water, and tail gas treatment systems for the collection and decomposition of ozone tail gas. In summary, existing process systems have low ozone utilization rates and require numerous auxiliary units, increasing the investment and management complexity of process applications. Summary of the Invention

[0005] The purpose of this invention is to address the above-mentioned shortcomings by providing a single-stage reaction system based on ozone recycling and multi-point dosing.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A single-stage reaction system based on ozone recycling and multi-point dosing includes: The reaction tower is divided into an ozone recycling zone, a buffer zone, a catalytic oxidation zone, and an effluent zone, which are connected sequentially from bottom to top. The inlet system is used to transport wastewater to the ozone recycling area of ​​the reaction tower; An ozone dosing system is used to add ozone to the buffer zone of the reaction tower. The ozone recycling system is used to collect ozone tail gas and residual ozone in the effluent of the reaction tower and re-add it to the ozone recycling area of ​​the reaction tower. The effluent system is connected to the effluent area and discharges the treated wastewater.

[0007] In one possible implementation, the ozone recycling zone has an inlet on the inner wall of the reaction tower, a water inlet distribution perforated pipe connected to the inlet and located inside the reaction tower, an ozone jet injection port on the inner wall of the reaction tower, a pipe connected to the ozone jet injection port and located inside the reaction tower, and a plurality of water inlet distribution perforated pipes on the pipe. The output end of the water inlet system is connected to the water inlet, and the wastewater is transported to the reaction tower through the water inlet distribution perforated pipe; The output end of the ozone recycling system is connected to the ozone jet injection port, which collects the ozone tail gas in the effluent area of ​​the reaction tower and the residual ozone in the effluent and transports it to the reaction tower through the water distribution perforated pipe.

[0008] In one possible implementation, the buffer zone has a first support plate with through holes disposed inside the reaction tower, an ozone distributor disposed on the first support plate, and an ozone injection port disposed on the inner wall of the reaction tower and located above the ozone distributor. The output of the ozone dosing system is connected to the ozone dosing port, which delivers ozone into the reaction tower and distributes it evenly in the buffer zone via an ozone distributor.

[0009] In one possible implementation, the ozone dosing system includes a micro / nano bubble generator; The ozone distributor includes a circular turntable rotatably mounted on a first support plate. Multiple propeller blades are located at the bottom of the turntable and are evenly distributed along the axis of the turntable. Multiple side-mounted plates are located at the top of the turntable, with one end of each plate located at the center of the turntable and the other end extending to the perimeter of the turntable. The multiple plates are evenly distributed along the axis of the turntable to generate a rotating water flow above the turntable while the turntable rotates.

[0010] In one possible implementation, the first support plate is designed as a frustum shape, smaller at the top and larger at the bottom, with a hollow interior. Only one through hole is provided on the first support plate and is located in the middle of the first support plate. A circular turntable is coaxially arranged with the through hole. The bottom of the ozone distributor has a support rod, which is connected to the first support plate to support the ozone distributor. The ozone distributor and the support rod are rotatably engaged.

[0011] In one possible implementation, the outlet of the ozone dosing port is positioned in the direction of rotation of the rotating water flow and is inclined toward the middle of the rotating water flow, wherein the output direction of the ozone dosing port does not point toward the center of the rotating disk.

[0012] In one possible implementation, the bottom of the turntable has a tapered slope that is wider at the top and narrower at the bottom.

[0013] In one possible implementation, the ozone dosing system includes an ozone dosing pipe, an air pipe, a water inlet pipe, and a micro / nano bubble generator. The input end of the ozone dosing tube is connected to the ozone source, and a first regulating valve and a second electromagnetic flow meter are installed on it to control the ozone delivery volume. The air pipe's inlet is connected to an air source, and it is equipped with a second regulating valve and a third electromagnetic flow meter to control the air delivery volume. The air pipe's outlet and the ozone dosing pipe's outlet are connected to the bypass interface on the micro-nano bubble generator through the same pipe body. The outlet of the inlet pipe is connected to the main input end of the micro-nano bubble generator. A water pump is installed on the inlet pipe, and the input end of the water pump is connected to the inside of the reaction tower to draw sewage from the reaction tower and pump it into the inlet pipe. A third regulating valve and a fourth electromagnetic flow meter are also installed on the inlet pipe to control the pumping volume of sewage. Micro-nano bubble generators are used to produce micro-nano bubbles and transport them to the buffer zone of the reaction tower.

[0014] In one possible implementation, the ozone recycling system includes a jet pump, the input of which is connected to the effluent area, and the output of which is connected to an ejector, the output of which is connected to the ozone recycling area. It also includes an exhaust duct, an exhaust fan, and an exhaust duct. The input end of the exhaust duct is connected to the top of the reaction tower, and the output end of the exhaust duct is connected to the exhaust fan. The exhaust fan is connected to the bypass interface on the ejector through the exhaust duct. The exhaust duct is equipped with a regulating valve and a first gas flow meter to control the air volume. It also includes an ozone replenishment pipe, one end of which is connected to an ozone source. A gas regulating valve and a second gas flow meter are installed on it to control the ozone delivery. The output end of the ozone replenishment pipe and the output end of the air outlet pipe are connected to the bypass interface on the jet injector through the same pipe body.

[0015] In one possible implementation, a water backwashing system and a gas backwashing system are also included for backwashing the reaction tower with water, gas, and combined gas and water.

[0016] The beneficial effects of this invention are reflected in: To address the challenges of using ozone oxidation for industrial wastewater with complex and recalcitrant organic components, which suffers from high catalyst consumption, low ozone utilization, and lengthy auxiliary facilities and processes, this paper proposes a novel ozone oxidation process system with a single-stage reaction tower for multi-point ozone recycling as its core equipment. This system couples direct ozone oxidation and catalytic oxidation processes in a single-stage reaction tower configuration, achieving a reduction in catalyst and ozone dosage while maintaining the overall degradation efficiency, thus optimizing both equipment investment and operating costs.

[0017] The ozone recycling system uses jet pumps and induced draft fans to return residual ozone from the system's effluent and exhaust gas, and then replenishes it to the pre-ozonation zone at the bottom of the reaction tower via jet release. This not only achieves the recycling of residual ozone but also improves the system's ozone utilization rate. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0019] Figure 1 This is a schematic diagram illustrating the working principle of the single-stage reaction system based on ozone recycling and multi-point dosing as described in this invention. Figure 2 This is a schematic diagram of the internal structure of the reaction tower described in this invention; Figure 3 This is a schematic diagram of the upper part of the turntable described in this invention; Figure 4 This is a schematic diagram of the bottom structure of the turntable described in this invention; Figure 5 This is a half-sectional schematic diagram of the turntable described in this invention.

[0020] In the picture: 1-Reaction tower; 11-Ozone recycling zone; 111-Vent port one; 112-Vent port two; 113-Water inlet; 114-Ozone jet injection port; 115-Water inlet distribution perforated pipe; 116-Pipeline; 117-Release device; 118-First observation hole; 12-Buffer zone; 121-First support plate; 122-Compressed air inlet; 123-Aeration perforated pipe; 124-Ozone injection port; 125-Ozone distribution... Device; 1251-Turntable; 1252-Propeller blade; 1253-Vertical plate; 126-Second observation hole; 13-Catalytic oxidation zone; 131-Second support plate; 132-Solid ozone catalyst; 133-Third observation hole; 14-Water outlet zone; 141-Return port; 142-Air inlet; 143-Automatic exhaust valve port; 144-Breathing valve; 145-Backwash drain port; 146-Water outlet; 147-Fourth observation hole; 2-Inlet system; 21-Suction valve; 22-Inlet pump; 23-Inlet pressure valve; 24-Pump outlet pressure gauge; 25-Outlet regulating valve; 26-First electromagnetic flow meter; 3-Ozone dosing system; 31-Ozone dosing pipe; 311-First gate valve; 312-First regulating valve; 313-Second electromagnetic flowmeter; 32-Air pipe; 321-Second gate valve; 322-Second regulating valve; 323-Third electromagnetic flowmeter; 33-Inlet pipe; 331-Pumping unit; 332-Third gate valve; 333-Third regulating valve; 334-Fourth electromagnetic flowmeter; 34-Micro / nano bubble generator; 4-Ozone recycling system; 41-Jet suction valve; 42-Jet pump; 43-Pump pressure valve; 44-Outlet regulating valve; 45-Fifth electromagnetic flow meter; 46-Pump outlet pressure gauge; 47-Exhaust duct; 48-Exhaust fan; 49-Outlet duct; 410-Regulating valve; 411-First gas flow meter; 412-Ozone replenishment pipe; 413-Gas regulating valve; 414-Second gas flow meter; 415-Ozone main pipe; 416-Ejector; 417-Jet bypass valve; 418-Jet main pipe; 419-Jet front end pressure gauge; 420-Jet rear end pressure gauge; 5-Water outlet system; 51-Tower outlet pipe; 52-Outlet shut-off valve; 53-Backwash outlet pipe; 54-Backwash outlet shut-off valve; 6-Water backwash system; 61-Backwash inlet valve; 62-Backwash pump; 63-Backwash pressure valve; 64-Backwash inlet shut-off valve; 65-Backwash pressure gauge; 7-Gas backwash system; 71-Roots blower; 72-Silencer; 73-Backwash gas injection valve; 74-Backwash inlet shut-off valve; 75-Backwash outlet shut-off valve. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left" and "right" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the position or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations of this invention.

[0024] like Figure 1-5 As shown, the present invention discloses a single-stage reaction system based on ozone recycling and multi-point dosing, which consists of core equipment reaction tower 1, water inlet system 2, ozone dosing system 3, ozone recycling system 4, water outlet system 5, water backwashing system 6 and gas backwashing system 7.

[0025] Reactor 1 is the core equipment of the system for realizing ozone recycling and oxidative degradation of organic matter in wastewater. Reactor 1 is divided into ozone recycling zone 11, buffer zone 12, catalytic oxidation zone 13 and effluent zone 14 from bottom to top.

[0026] The ozone recycling zone 11 requires a residence time of no less than 30 minutes and a height of no less than 1.5 meters. The ozone recycling zone 11 is a pre-reaction zone that utilizes residual ozone in the system's effluent and exhaust gas for recycling. The detailed structural components of the ozone recycling zone 11 include vent outlet 111 and vent outlet 112, inlet 113, ozone jet injection port 114, inlet water distribution perforated pipe 115, pipe 116, release device 117, and first observation port 118. The inlet water distribution perforated pipe 115 is connected to the inlet 113. Wastewater enters the inlet water distribution perforated pipe 115 through the inlet 113 and is distributed through the inlet water distribution perforated pipe 115. Multiple release devices 117 are provided and installed on the pipe 116. The pipe 116 is connected to the ozone jet injection port 114. The residual ozone in the system effluent and exhaust gas enters the pipe 116 through the ozone jet injection port 114 and is released in the ozone recycling zone 11 through the release device 117, oxidizing and degrading the relatively easily degradable organic matter in the wastewater components.

[0027] Buffer zone 12 requires a residence time of no less than 10 minutes and a height of no less than 0.3 m. Buffer zone 12 is a premixing zone for the addition of external ozone gas into the reaction tower. The detailed structural components of buffer zone 12 include a first support plate 121, a compressed air inlet 122, an aeration perforated pipe 123, an ozone dosing port 124, an ozone distributor 125, and a second observation port 126. The first support plate 121 has through holes through which gas and wastewater from the ozone recycling zone 11 pass to buffer zone 12. External ozone gas is added to buffer zone 12 through ozone dosing port 124. The main function of the ozone distributor 125 is to evenly distribute the added ozone gas within buffer zone 12. The ozone distributor 125 can be an aeration disc, which can be a microporous aeration titanium disc. Microporous aeration titanium discs are more resistant to ozone erosion than membrane aeration discs. In this embodiment, a micro-nano bubble generator 34 is used to add ozone and aerate the air. The ozone inlet 124 serves as the output port of the micro-nano bubble generator 34, which ozonates the ozone into micro-nano bubbles and inputs them into the buffer zone 12. The surface of the micro-nano bubbles is rich in negative charges. At the moment of bubble collapse, a large number of hydroxyl radicals are generated, which have extremely strong oxidizing properties and can rapidly decompose organic pollutants in the water. It should be noted that although micro- and nano-bubbles can be evenly distributed and released within the buffer zone 12 through an aeration disc or by laying pipes within the buffer zone 12, the micro- and nano-bubbles traveling in the pipes tend to accumulate on the pipe walls. Some of the micro- and nano-bubbles cannot be released inside the buffer zone 12 at all, affecting the decomposition effect. Although the distance between the output port of the micro- and nano-bubble generator and the ozone dosing port 124 can be shortened by adjusting the setting position of the micro- and nano-bubble generator (or even by directly connecting the output port of the micro- and nano-bubble generator to the ozone dosing port 124), the pipes located inside the buffer zone 12 cannot be shortened. Therefore, this application uses an ozone distributor 125 with a different structural form in conjunction with the micro- and nano-bubble generator.

[0028] Specifically, the ozone distributor 125 includes a circular turntable 1251 rotatably mounted on a first support plate 121. Multiple propeller blades 1252 are disposed at the bottom of the turntable 1251 and are evenly distributed along the axis of the turntable 1251. Multiple side-mounted upright plates 1253 are disposed at the top of the turntable 1251, with one end of each upright plate 1253 located at the center of the turntable 1251 and the other end extending to the perimeter of the turntable 1251. The multiple upright plates 1253 are evenly distributed along the axis of the circular turntable 1251. During operation, the lower... The gas and wastewater in the ozone recycling zone 11 move upwards and, when they pass the propeller blades 1252 at the bottom of the turntable 1251, they drive the propeller blades 1252 to rotate, which in turn causes the turntable 1251 to rotate. The rotating turntable 1251 drives multiple vertical plates 1253 to rotate, causing the water flow in the buffer zone 12 to rotate. At this time, the micro-nano bubbles entering the buffer zone 12 are relatively evenly distributed in the buffer zone 12 under the drive of the rotating water flow. At the same time, the rotating water flow can also prolong the residence time of the micro-nano bubbles in the buffer zone 12, further improving the decomposition effect.

[0029] To better guide the gas and wastewater in the ozone recycling zone 11 to the area below the ozone distributor 125 and increase the rotational speed and torque of the turntable 1251, the first support plate 121 is designed as a frustum-shaped cone, wider at the bottom than the top. The cone is hollow inside, and a through-hole is located in the center of the first support plate 121. A portion of the bottom of the ozone distributor 125 extends into this through-hole. The bottom of the ozone distributor 125 has a support rod connected to the first support plate 121 to support the ozone distributor 125. The ozone distributor 125 rotates in conjunction with the support rod. During operation, the gas and wastewater gather at the bottom of the turntable 1251 through the first support plate 121 and enter the buffer zone 12 through the turntable 1251, increasing the rotational speed and torque of the turntable 1251. Furthermore, the output direction of the ozone inlet 124 can be set along the tangential direction of the rotating water flow to accelerate the rotation of the water flow. However, this method can easily cause micro-nano bubbles to come into contact with the inner wall of the reaction tower 1. Therefore, the outlet of the ozone inlet 124 can be set along the rotation direction of the rotating water flow and tilted towards the middle of the rotating water flow. The output direction of the ozone inlet 124 does not point to the center of the turntable 1251 (if it points to the center of the turntable 1251, it will generate a certain resistance to the rotating water flow. Although not pointing to the center of the turntable 1251 will also disturb the rotating water flow, the overall disturbance is limited because its outlet direction is roughly the same as the rotation direction of the rotating water flow. And when the angle is set appropriately, there is a certain situation of accelerating the rotation of the water flow).

[0030] Furthermore, the bottom of the turntable 1251 has a conical slope that is wider at the top and narrower at the bottom. This slope guides the water flow and air bubbles to be discharged from the side of the turntable 1251 with a certain acceleration during their ascent, thereby giving the turntable 1251 a tangential force and driving it to rotate. Without this conical slope, the water flow and air bubbles would first collide with the bottom surface of the turntable 1251 and then be squeezed to one side along the plane of the bottom of the turntable 1251, resulting in a loss of some energy.

[0031] It should be noted that the micro-nano bubble generator 34 is common knowledge to those skilled in the art, so it will not be described in detail here.

[0032] The catalytic oxidation zone 13 requires a residence time of no less than 30 minutes and a height of no less than 1 meter. This zone is the catalytic oxidation reaction zone for the synergistic degradation of organic matter in wastewater by ozone and catalyst. The detailed structure of this zone includes a second support plate 131, a solid ozone catalyst 132, and a third observation hole 133. The second support plate 131 has holes, allowing water in the buffer zone 12 to pass through it and enter the catalytic oxidation zone 13.

[0033] The effluent zone 14 includes a clear water zone and an elevated section above the clear water zone. The clear water zone must be at least 0.8m high, and the elevated section at least 0.3m high. This zone is the end of the reaction tower. The detailed structures included in the effluent zone 14 are: a reflux inlet 141, an air vent 142, an automatic exhaust valve 143, a breather valve 144, a backwash drain outlet 145, a water outlet 146, and a fourth observation port 147.

[0034] The first observation hole 118, the second observation hole 126, the third observation hole 133 and the fourth observation hole 147 mentioned above are all for staff to observe the situation inside the tower.

[0035] The function of the inlet system 2 is to pump the wastewater to be treated to the reaction tower 1. This system consists of a pump inlet valve 21, an inlet pump 22, an inlet pressure valve 23, a pump outlet pressure gauge 24, an inlet regulating valve 25, and a first electromagnetic flowmeter 26. The selection of the inlet pump 22 is determined based on the system's processing capacity and required pressure. The system can achieve adjustment and stabilization of the inlet flow rate through interlocking control of the inlet pump 22, the inlet regulating valve 25, and the first electromagnetic flowmeter 26.

[0036] The ozone dosing system 3 is used to add ozone to the reaction tower 1. This system includes an ozone dosing pipe 31, an air pipe 32, a water inlet pipe 33, and a micro / nano bubble generator 34. The ozone dosing pipe 31 is sequentially equipped with a first gate valve 311, a first regulating valve 312, and a second electromagnetic flowmeter 313; the air pipe 32 is sequentially equipped with a second gate valve 321, a second regulating valve 322, and a third electromagnetic flowmeter 323; the ozone generator is connected to the ozone dosing pipe 31 and produces a corresponding amount of ozone based on the wastewater quality. The input end of the air pipe 32 is connected to an external air source or directly exposed to the air. The output end of the air pipe 32 and the output end of the ozone dosing pipe 31 are connected to the bypass interface of the micro-nano bubble generator 34 through the same pipe body. The water inlet pipe 33 is sequentially equipped with a pumping unit 331 (i.e., a water pump), a third gate valve 332, a third regulating valve 333, and a fourth electromagnetic flowmeter 334. The outlet of the water inlet pipe 33 is connected to the main input end of the micro-nano bubble generator 34. The inlet of the pumping unit 331 can be connected to the ozone recycling zone 11, the buffer zone 12, or the effluent zone 14 to extract wastewater from the tower and pump the wastewater into the micro-nano bubble generator 34. The ozone dosage of the system is determined according to the wastewater quality and treatment effect. The system can achieve uniform distribution and constant flow of ozone gas through the interlock control of regulating valve and gas electromagnetic flow meter. The setting of air pipe 32 can provide sufficient gas to micro-nano bubble generator 34 during and after ozone gas addition, so that micro-nano bubble generator 34 can work continuously (after ozone addition is completed, micro-nano bubble generator 34 continues to work without stopping to perform aeration).

[0037] The micro-nano bubble generator 34 in this application is an ejector. The outlet of the ejector can be directly connected to the tower body. The output end of the air pipe 32 and the output end of the ozone dosing pipe 31 are connected to the bypass interface of the ejector through a single pipe.

[0038] The ozone recycling system 4 collects the ozone tail gas and residual ozone in the effluent zone 14 of the reaction tower 1 and re-injects it into the influent end of the reaction tower 1 (i.e., the ozone recycling zone 11) to achieve the purpose of recycling residual ozone. The effluent from the reaction tower 1 is returned through a jet pump 42, the flow rate of which is selected according to 50% to 150% of the influent pump 22; the ozone tail gas is collected by an induced draft fan 48, the air volume of which is 1.1 to 1.3 times the maximum ozone injection flow rate of the system. The system consists of a jet suction valve 41, a jet pump 42, a pump pressure valve 43, an outlet regulating valve 44, a fifth electromagnetic flowmeter 45, a pump outlet pressure gauge 46, an exhaust pipe 47, an exhaust fan 48, an outlet pipe 49, a regulating air valve 410, a first gas flowmeter 411, an ozone replenishment pipe 412, a gas regulating valve 413, a second gas flowmeter 414, an ozone main pipe 415, a jet injector 416, a jet pipe bypass valve 417, a jet main pipe 418, a jet front end pressure gauge 419, and a jet rear end pressure gauge 420.

[0039] The effluent system 5 includes the reaction tower effluent system and the backwash effluent system. The system consists of the tower effluent pipe 51, the effluent shut-off valve 52, the backwash effluent pipe 53, and the backwash effluent shut-off valve 54.

[0040] The water backwash system 6 is used for backwashing reaction tower 1. This system consists of a backwash inlet valve 61, a backwash pump 62, a backwash pressure valve 63, a backwash inlet shut-off valve 64, and a backwash pressure gauge 65. The backwash pump flow rate is set according to a backwash intensity of 5~8 L / (m³). •s) Configuration, the pressure is determined based on system pressure calculation.

[0041] The gas backwash system 7 is used for backwashing the gas in reaction tower 1. This system consists of a Roots blower 71, a silencer 72, a backwash gas injection valve 73, a backwash inlet shut-off valve 74, and a backwash outlet shut-off valve 75. The Roots blower's airflow is set at a backwash intensity of 10~15 L / (m³). •s) Configuration, the pressure is determined based on system pressure calculation.

[0042] When the system is operating normally, the working procedure for treating wastewater is as follows: When treating wastewater in reaction tower 1, residual ozone from the effluent outlet of the ozone recycling system 4 is mixed with the influent in the ozone recycling system 4 at the bottom of reaction tower 1. The residual ozone is then added back to the influent zone (i.e., ozone recycling zone 1) in the form of nanobubbles through the ejector 416 to pre-oxidize the organic matter in the wastewater and oxidize and degrade the relatively easily degradable organic matter in the wastewater components. Ozone from the ozone addition system 3 is added to the buffer zone 12 of the reaction tower through the ozone distributor 125. After the ozone added to the buffer zone 12 is pre-mixed with the wastewater in reaction tower 1, it rises together with the treated wastewater to the catalytic oxidation zone 13 of the reaction tower. The ozone catalyst activates the ozone to generate a free radical system with a higher oxidation potential. The free radicals generated by the activation are used to further degrade the recalcitrant organic matter in the wastewater. The effluent from catalytic oxidation zone 13 enters effluent zone 14. The dissolved residual ozone and ozone tail gas in the effluent are mixed and recycled back to the ozone recycling zone at the bottom of the reaction tower via jet pump 42 and induced draft fan 48, respectively. The effluent from effluent zone 14 is discharged from the reaction tower through effluent pipe 51. The workflow consists of the following steps: Operational preparation: During normal operation, the backwash pump 62 and the Roots blower 71 are stopped. The backwash water inlet shut-off valve 64, the backwash air inlet shut-off valve 74, the backwash air outlet shut-off valve 75, and the backwash water outlet shut-off valve 54 are all closed, while the water outlet shut-off valve 52 is open.

[0043] Water intake: First, start the water intake system 2 to pump the wastewater to be treated to the inlet 113 of the reaction tower 1 through the water intake pump 22 (frequency converter pump), and distribute the water evenly upward through the water intake distribution perforated pipe 115.

[0044] Start the ozone dosing system: When the liquid level in the reaction tower exceeds the upper layer of the catalytic oxidation zone 13, start the ozone dosing system 3 to add ozone into the reaction tower 1.

[0045] To start the recycling system: First, start the induced draft fan 48 and adjust its flow rate using the online instrument regulating valve 410 and gas flow meter 411. When the inlet water level in the tower reaches 0.2m above the reflux port 141, start the jet pump 42 and control the reflux flow rate using the online instrument outlet regulating valve 44 and the fifth electromagnetic flow meter 45. The reflux liquid and gas are mixed through the ejector 416 and sent to the ozone jet injection port 114 of the reaction tower, and then injected into the reaction tower 1 through the release device 117. The pressure difference between the online pressure gauges (jet front pressure gauge 419 and jet rear pressure gauge 420) at the front and rear ends of the ejector 416 is used to indicate the operating status of the ejector 416. To achieve a better gas-liquid mixing effect, the pressure difference is controlled within 0.05~0.1MPa. When the ejector 416 is under maintenance, close the valves at both ends of the ejector 416 and open the valve on the bypass pipe 417. The effluent from the ejector pump 42 can then be transported to the reaction tower through the bypass pipe 417. All valves on the ozone replenishment pipe 412 are normally closed. Depending on the influent water quality and treatment requirements, if the residual ozone level in the system is insufficient, an appropriate amount of ozone can be added to the system by adjusting the gas regulating valve 413 on the ozone replenishment pipe 412.

[0046] Water discharge: The system water is discharged from the reaction tower through water discharge pipe 51.

[0047] The operating procedure for system backwashing is as follows: Backwashing preparation: The backwashing cycle of the system is generally 7-10 days / time. The preparation work for backwashing includes: stopping the water inlet system 2, ozone dosing system 3 and ozone recycling system 4, shutting down the water pumps and blowers of the corresponding systems, and simultaneously closing the water inlet regulating valve 25, the first regulating valve 312, the second regulating valve 322, the third regulating valve 333, the water outlet regulating valve 44, the regulating air valve 410 and the gas regulating valve 413, and opening the backwash gas shut-off valve 75; then opening the vent valve 119 of the reaction tower 1 to lower the liquid level in the tower to below the solid ozone catalyst layer 133.

[0048] After the backwashing preparation is completed, the backwashing is carried out according to the process of gas backwashing - water backwashing - combined gas and water backwashing.

[0049] Gas backwashing: First, perform a separate gas backwash for 5-10 minutes. Start the Roots blower 71 and open the backwash inlet shut-off valve 74. Use compressed gas to perform gas friction washing on the catalyst bed. The gas inside the tower is discharged from the reaction tower through the backwash outlet pipe and valve 75. The Roots blower is operated at a backwash intensity of 10-15 L / ( ·s) configuration, after 5~10 minutes, shut off the Roots blower 71 and the backwash air inlet shut-off valve 74.

[0050] Water backwashing: Then perform a separate water rinse for 10-15 minutes. Turn on the backwash pump 62, backwash inlet shut-off valve 64, and backwash outlet shut-off valve 54 to rinse the internal components and catalyst bed with clean water. The backwash water is discharged from the tower through the backwash outlet pipe 53 and backwash outlet shut-off valve 54. The backwash pump operates at a backwash intensity of 5-8 L / ( ·s) configuration.

[0051] Combined air and water backwashing: Perform a combined air and water backwash for 5-10 minutes. After the water backwash is complete, restart the Roots blower 71 and open the backwash air inlet shut-off valve 74. After the combined air and water backwashing lasts for 5-10 minutes, shut off the backwash pump 62, Roots blower 71, backwash water inlet shut-off valve 64, and backwash air inlet shut-off valve 74. After the backwash water and backwash air in the reaction tower have been discharged, close the backwash water outlet shut-off valve 54 and the backwash air outlet shut-off valve 75. The backwashing process is now complete.

[0052] Example 1: To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0053] For secondary biological effluent from industrial wastewater, with COD (chemical oxygen demand) of 100-150 mg / L, B / C (biodegradability ratio) <0.05, and TDS (total dissolved solids) ≤4000 mg / L, the wastewater is treated using a single-stage reaction system and equipment based on ozone recycling and multi-point dosing.

[0054] The core equipment parameters of the single-stage reaction tower for ozone recycling and multi-point dosing are as follows: The reaction tower 1 is divided into an ozone recycling zone 11, a buffer zone 12, a catalytic oxidation zone 13, and an effluent zone 14 from bottom to top. In this embodiment, the ozone recycling zone 11 has a height of 3m and a residence time of 36min; the buffer zone 12 has a height of 0.5m and a residence time of 6min; the catalytic oxidation zone 13 has a height of 2.5m and an empty catalyst bed residence time of 30min; the clear water zone in the effluent zone 14 has a height of 1m and a residence time of 12min; the superelevation of the reaction tower is 0.3m. The total height of the reactor (including superelevation) is 7.3m, and the total residence time inside the tower is approximately 84min.

[0055] The treatment process and operating parameters of a single-stage reaction system based on ozone recycling and multi-point dosing are as follows: Water intake: First, start the water intake system 2 to pump the wastewater to be treated to the inlet of the reaction tower 1 through the water intake pump (frequency converter) 22, and distribute the water evenly upward through the water intake distribution perforated pipe 115.

[0056] Start the ozone dosing system: When the liquid level in the reaction tower exceeds the upper layer of catalytic oxidation zone 13, start the ozone dosing system 3 to add ozone into reaction tower 1. Control the ozone dosage to be between 60 and 120 mg / L, depending on the water quality and treatment flow rate.

[0057] To start the recycling system: First, start the induced draft fan 48, adjusting the fan flow rate via the online instrument regulating valve 410 and gas flow meter 411. When the inlet water level in the tower reaches 0.2m above the reflux port 141, start the jet pump 42, controlling the system reflux flow rate via the online instrument regulating valve 44 and electromagnetic flow meter 45. The jet pump 42 flow rate is selected based on 100% of the inlet pump 22, and the induced draft fan 4 air volume is set at an induced draft fan air volume: jet pump 42 flow rate of (0.1~0.3):1. The reflux liquid and gas are mixed through the jet injector 416 and sent to the ozone jet injection port 114 of the reaction tower, and then injected into the reaction tower 1 through the release device 117.

[0058] Water discharge: The system water is discharged from the reaction tower through water discharge pipe 51.

[0059] Operating the system according to the above process parameters and continuously monitoring the influent and effluent for 600 hours, when the ozone concentration in the water was 60~120mg / L, the COD of the effluent was less than 50mg / L, and the B / C ratio of the effluent was 0.23~0.34. No ozone tail gas was emitted from the system, and the residual ozone concentration in the effluent was <0.1mg / L.

[0060] Example 2: For industrial wastewater from fine chemical enterprises, the COD in the wastewater is 400~600mg / L, the influent B / C ratio is about 0.05~0.15, and the TDS is ≤5000mg / L. The wastewater is pretreated using a single-stage reaction system and equipment based on ozone recycling and multi-point dosing.

[0061] The core equipment parameters of the single-stage reaction tower for ozone recycling and multi-point dosing are as follows: The reaction tower 1 is divided into an ozone recycling zone 11, a buffer zone 12, a catalytic oxidation zone 13, and an effluent zone 14 from bottom to top. In this embodiment, the ozone recycling zone 11 has a height of 3.5m and a residence time of 42min; the buffer zone 12 has a height of 0.5m and a residence time of 6min; the catalytic oxidation zone 13 has a height of 1.5m and an empty catalyst bed residence time of 18min; the clear water zone in the effluent zone 14 has a height of 0.8m and a residence time of 10min; the superelevation of the reaction tower is 0.3m. The total height of the reactor (including superelevation) is 6.6m, and the total residence time inside the tower is approximately 76min.

[0062] The treatment process and operating parameters of a single-stage reaction system based on ozone recycling and multi-point dosing are as follows: Water intake: First, start the water intake system 2 to pump the wastewater to be treated to the inlet of the reaction tower 1 through the water intake pump (frequency converter) 22, and distribute the water evenly upward through the water intake distribution perforated pipe 115.

[0063] Activate the ozone dosing system: When the liquid level in the reaction tower exceeds the upper layer of the catalytic oxidation zone 13, activate the ozone dosing system 3 to add ozone into the reaction tower 1. Control the ozone dosing rate at this location to be between 15 and 20 mg / L.

[0064] Start the recycling system: First, start the induced draft fan 48, and adjust the fan flow rate through the online instrument regulating valve 410 and gas flow meter 411. When the inlet water level in the tower reaches 0.2m above the reflux port 141, start the jet pump 42, and control the system reflux flow rate through the online instrument regulating valve 44 and electromagnetic flow meter 45. The jet pump 42 flow rate is selected according to 50% of the inlet pump 22, and the induced draft fan 48 air volume is set at (0.05~0.10):1 (induced draft fan air volume: jet pump 42 flow rate). Adjust the gas regulating valve 413 on the ozone replenishment pipe 412 to replenish ozone to the system at this point, with an ozone dosage between 15~20mg / L. The reflux liquid, reflux ozone tail gas, and replenishment ozone gas are mixed through the jet injector 416 and sent to the ozone jet injection port 114 of the reaction tower, and then added into the reaction tower 1 through the release device 117.

[0065] Water discharge: The system water is discharged from the reaction tower through water discharge pipe 51.

[0066] When the COD of industrial wastewater influent is 400~500mg / L, B / C < 0.1, and TDS ≤ 4000mg / L, a single-stage reaction system and equipment based on ozone recycling and multi-point dosing are used for deep treatment.

[0067] When the COD in industrial wastewater is 400~600 mg / L, the influent B / C ratio is approximately 0.05~0.15, and the TDS ≤ 5000 mg / L, operating according to the above process parameters, the COD removal rate is approximately 8%~12%, and the effluent B / C ratio is approximately 0.20~0.28. The system emits no ozone exhaust gas, and the residual ozone concentration in the effluent is <0.05mg / L.

[0068] It should be noted that in this specification, relational terms such as first and second are used only to distinguish one entity from several other entities, and do not necessarily require or imply any such actual relationship or order between these entities.

[0069] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0070] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the present invention.

Claims

1. A single-stage reaction system based on ozone recycling and multi-point dosing, characterized in that, include: The reaction tower is divided into an ozone recycling zone, a buffer zone, a catalytic oxidation zone and an effluent zone, which are connected sequentially from bottom to top. The water inlet system is used to transport wastewater to the ozone recycling area of ​​the reaction tower; An ozone dosing system for adding ozone to the buffer zone of the reaction tower; An ozone recycling system is used to collect ozone tail gas and residual ozone in the effluent from the effluent zone and re-add it to the ozone recycling zone of the reaction tower. The effluent system is connected to the effluent area to discharge the treated wastewater.

2. The single-stage reaction system based on ozone recycling and multi-point dosing according to claim 1, characterized in that, The ozone recycling area has a water inlet on the inner wall of the reaction tower, a water inlet and distribution perforated pipe connected to the water inlet and located inside the reaction tower, an ozone jet injection port on the inner wall of the reaction tower, a pipe connected to the ozone jet injection port and located inside the reaction tower, and multiple water inlet and distribution perforated pipes on the pipe. The output end of the water inlet system is connected to the water inlet, and the wastewater is transported to the reaction tower through the water inlet distribution perforated pipe. The output end of the ozone recycling system is connected to the ozone jet injection port, which collects the ozone tail gas in the effluent zone and the residual ozone in the effluent and transports it to the reaction tower through the water distribution perforated pipe.

3. The single-stage reaction system based on ozone recycling and multi-point dosing according to claim 1, characterized in that, The buffer zone has a first support plate disposed inside the reaction tower and having through holes thereon, an ozone distributor disposed on the first support plate, and an ozone injection port disposed on the inner wall of the reaction tower and located above the ozone distributor. The output of the ozone dosing system is connected to the ozone dosing port, which delivers ozone into the reaction tower and distributes it evenly in the buffer zone via the ozone distributor.

4. The single-stage reaction system based on ozone recycling and multi-point dosing according to claim 3, characterized in that, The ozone dosing system includes a micro / nano bubble generator; The ozone distributor includes a circular turntable rotatably mounted on the first support plate. Multiple propeller blades are located at the bottom of the turntable and are evenly distributed along the axis of the circular turntable. Multiple side-mounted plates are located at the top of the turntable, with one end of each plate located at the center of the turntable and the other end extending outwards to the perimeter of the turntable. The multiple side-mounted plates are evenly distributed along the axis of the circular turntable to generate a rotating water flow above the turntable while it rotates.

5. The single-stage reaction system based on ozone recycling and multi-point dosing according to claim 4, characterized in that, The first support plate is a frustum-shaped cone, smaller at the top and larger at the bottom, and hollow inside. There is one through hole in the middle of the first support plate. The turntable is coaxially arranged with the through hole. The bottom of the ozone distributor has a support rod, which is connected to the first support plate to support the ozone distributor. The ozone distributor and the support rod are rotatably engaged.

6. The single-stage reaction system based on ozone recycling and multi-point dosing according to claim 4, characterized in that, The outlet of the ozone dosing port is set in the direction of rotation of the rotating water flow and is inclined toward the middle of the rotating water flow. The output direction of the ozone dosing port does not point to the center of the turntable.

7. The single-stage reaction system based on ozone recycling and multi-point dosing according to claim 4, characterized in that, The bottom of the turntable has a conical slope that is wider at the top and narrower at the bottom.

8. The single-stage reaction system based on ozone recycling and multi-point dosing according to claim 1, characterized in that, The ozone dosing system includes an ozone dosing pipe, an air pipe, a water inlet pipe, and a micro / nano bubble generator; The input end of the ozone dosing pipe is connected to an ozone source, and the ozone dosing pipe is equipped with a first regulating valve and a second electromagnetic flow meter to control the ozone delivery volume. The air pipe is connected to an air source at its input end. The air pipe is equipped with a second regulating valve and a third electromagnetic flow meter to control the air delivery volume. The output end of the air pipe and the output end of the ozone dosing pipe are connected to the bypass interface on the micro-nano bubble generator through the same pipe body. The outlet of the inlet pipe is connected to the main input end of the micro-nano bubble generator. A water pump is installed on the inlet pipe, and the input end of the water pump is connected to the interior of the reaction tower for pumping wastewater from the reaction tower into the inlet pipe. A third regulating valve and a fourth electromagnetic flow meter are also installed on the inlet pipe for controlling the pumping rate of wastewater. The micro / nano bubble generator is used to produce micro / nano bubbles and transport them to the buffer zone of the reaction tower.

9. The single-stage reaction system based on ozone recycling and multi-point dosing according to claim 1, characterized in that, The ozone recycling system includes a jet pump, an exhaust duct, an exhaust fan, an exhaust duct, and an ozone replenishment duct. The input end of the jet pump is connected to the water outlet area, and the output end is connected to an ejector. The output end of the ejector is connected to the ozone recycling area. The input end of the induced draft pipe is connected to the top of the reaction tower, and the output end of the induced draft pipe is connected to the induced draft fan. The induced draft fan is connected to the bypass interface on the ejector through the outlet pipe. The outlet pipe is equipped with a regulating valve and a first gas flow meter to control the air volume. The ozone replenishment pipe is connected to the ozone source. The ozone replenishment pipe is equipped with a gas regulating valve and a second gas flow meter to control the ozone delivery. The output end of the ozone replenishment pipe and the output end of the air outlet pipe are connected to the bypass interface on the jet injector through the same pipe body.

10. The single-stage reaction system based on ozone recycling and multi-point dosing according to claim 1, characterized in that, It also includes a water backwashing system and a gas backwashing system for performing water backwashing, gas backwashing, and combined gas and water backwashing on the reaction tower.

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