A multi-stage catalytic fluidized bed treatment system for recalcitrant wastewater

Abstract

This invention relates to the field of industrial wastewater treatment and catalytic oxidation reaction equipment, specifically a multi-stage catalytic fluidized bed treatment system for recalcitrant wastewater, comprising a treatment unit, a feeding unit, a monitoring unit, an execution unit, and a control unit. The treatment unit includes a vertical cylindrical fluidized bed reactor, internally consisting of a pre-oxidation section, a deep catalytic oxidation section, and a solid-liquid separation section from top to bottom. The control unit adjusts the opening of the first porous grid plate according to the organic matter concentration and adjusts the gas supply ratio of the first and second gas supply rings according to the dissolved oxygen concentration, so that the wastewater first undergoes pre-oxidation and chain breaking in the same reactor, and then undergoes deep catalytic oxidation. The purified effluent is discharged through the purified effluent pipe, and the catalyst carrier is returned through the differential pressure return pipe to continue participating in the reaction, realizing staged degradation and catalyst carrier return.

Description

Technical Field

[0001] This invention relates to the field of industrial wastewater treatment and catalytic oxidation reaction equipment, specifically a multi-stage catalytic fluidized bed treatment system for recalcitrant wastewater. Background Technology

[0002] In existing recalcitrant wastewater treatment systems, the oxidation reaction device, solid-liquid separation device, and catalyst carrier recovery device are usually set up separately. The wastewater is purified and discharged after passing through pretreatment, oxidation degradation, and separation and recovery in sequence. The oxidizing gas is sent into the reaction zone through the gas supply component to maintain the reaction.

[0003] In existing treatment systems, some devices achieve the gradual degradation of organic matter through series reaction towers or multi-stage separation equipment. The residence time, gas supply ratio, and carrier circulation status between different reaction zones largely depend on preset parameters. When wastewater concentration fluctuates, dissolved oxygen changes, or the resistance of the separation section increases, it is usually necessary to adjust multiple devices separately or shut down for cleaning. The system process is long and the operation coordination is poor.

[0004] However, the above treatment methods are prone to problems such as unreasonable distribution of residence time in the reaction zone, insufficient supply of oxidant in the deep oxidation zone, and untimely recovery of catalyst carrier after blockage in the solid-liquid separation section. This leads to unstable chain breaking and mineralization of recalcitrant organic matter, resulting in decreased treatment efficiency and poor system operation stability. Summary of the Invention

[0005] The purpose of this invention is to provide a multi-stage catalytic fluidized bed treatment system for recalcitrant wastewater, solving the following technical problems:

[0006] By integrating pre-oxidation, deep oxidation, and separation and recovery processes within a single fluidized bed reactor, the need for a multi-tower series connection structure is eliminated. Based on feedback from system operating status parameters, the hydraulic resistance and gas supply distribution ratio in different sections of the reactor are dynamically adjusted.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] A multi-stage catalytic fluidized bed treatment system for recalcitrant wastewater includes: a treatment unit that receives recalcitrant wastewater and oxidizing gas, and outputs purified effluent; the treatment unit includes a vertical cylindrical fluidized bed reactor, wherein the fluidized bed reactor has, from top to bottom, a pre-oxidation section, a deep catalytic oxidation section, and a solid-liquid separation section; a first porous grid is provided between the pre-oxidation section and the deep catalytic oxidation section, and a second porous grid is provided between the deep catalytic oxidation section and the solid-liquid separation section; the solid-liquid separation section is provided with a purified effluent pipe, and the side wall of the fluidized bed reactor is provided with an independent carrier replenishment port;

[0009] The feeding unit receives external gas and outputs the distributed oxidizing gas and refluxed catalyst carrier to the processing unit. The feeding unit includes a water inlet distributor located at the top of the pre-oxidation section, a first gas supply ring pipe located at the bottom of the pre-oxidation section, a second gas supply ring pipe located at the bottom of the deep catalytic oxidation section, a differential pressure reflux pipe connected to the side wall of the solid-liquid separation section and communicating with the deep catalytic oxidation section, and a gas supply regulating valve for adjusting the gas supply ratio of the first gas supply ring pipe and the second gas supply ring pipe.

[0010] The monitoring unit includes a first organic matter concentration sensor located at the water inlet distributor, a second organic matter concentration sensor located at the bottom of the pre-oxidation section, a dissolved oxygen sensor located in the deep catalytic oxidation section, and a differential pressure sensor located in the solid-liquid separation section. The monitoring unit is used to generate real-time status signals.

[0011] The execution unit includes a first pneumatic actuator mounted on a first perforated grid plate, a second pneumatic actuator mounted on a second perforated grid plate, and a backwash water pump connected to the purified water outlet pipe;

[0012] The control unit receives real-time status signals, generates adjustment commands, and transmits them to the actuator and the air supply regulating valve.

[0013] Optionally, the control unit has a built-in dwell time control program, which includes:

[0014] Record the organic matter concentration at the bottom of the pre-oxidation section as measured by the second organic matter concentration sensor, and the organic matter concentration at the inlet water distributor as measured by the first organic matter concentration sensor;

[0015] Determine whether the measured organic matter concentration at the bottom of the pre-oxidation section is higher than the preset target outlet concentration of the pre-oxidation section;

[0016] The configuration is as follows: If the measured organic matter concentration at the bottom of the pre-oxidation section is higher than the preset target outlet concentration of the pre-oxidation section, then based on the preset adjustment model, the basic opening setting value used to give the default opening benchmark under normal load, and the adjustment gain coefficient used to reflect the amplification of the change in grid opening due to concentration deviation, the through-hole opening of the first porous grid is calculated, and a reduction opening command is generated. The first pneumatic actuator is controlled to execute the reduction opening command to reduce the opening of the first porous grid, increase the hydraulic resistance of the wastewater flowing downward, until the residence time of the pre-oxidation section accounts for 15% to 25% of the total residence time, and the adjustment result is fed back to the control unit; otherwise, the current opening is kept unchanged.

[0017] The adjustment model is configured as follows: based on the deviation between the organic matter concentration at the bottom of the pre-oxidation section and the preset target outlet concentration of the pre-oxidation section, the aperture of the first porous grid plate is negatively compensated and adjusted.

[0018] Optionally, the control unit has a built-in gas supply ratio control program, which includes:

[0019] Record the dissolved oxygen concentration within the deep catalytic oxidation zone as measured by the dissolved oxygen sensor;

[0020] Determine whether the measured dissolved oxygen concentration is lower than the preset target dissolved oxygen concentration setting value;

[0021] The configuration is as follows: if the measured dissolved oxygen concentration is lower than the preset target dissolved oxygen concentration setting value, the target gas supply ratio of the second gas supply ring is calculated according to the gas supply distribution model, and a gas distribution switching command is generated. The gas supply regulating valve is controlled to execute the gas distribution switching command, increase the gas supply ratio of the second gas supply ring to determine the remaining gas supply, and allocate the remaining gas supply to the first gas supply ring to enhance the oxidation reaction in the deep catalytic oxidation section. The distribution status is then fed back to the control unit. Otherwise, the current gas supply ratio remains unchanged.

[0022] The gas supply allocation model is configured as follows: based on the difference between the measured dissolved oxygen concentration and the target dissolved oxygen concentration setting, the gas supply allocated to the second gas supply ring pipe is dynamically calculated and increased.

[0023] Optionally, the solid-liquid separation section is equipped with a built-in multi-stage filter; the system has a normal separation state and a backwashing operation state, and its state switching and execution process includes:

[0024] Under normal separation conditions, the operating pressure difference between the inner and outer sides of the built-in multi-stage filter screen is recorded in real time by the differential pressure sensor.

[0025] Determine whether the operating differential pressure is greater than or equal to the preset backflushing trigger differential pressure threshold to form an over-limit state, and determine whether the duration of the over-limit state exceeds the preset duration threshold.

[0026] The system is configured such that if the operating differential pressure is greater than or equal to the backwash trigger differential pressure threshold and the duration exceeds the preset duration threshold, the system will automatically switch to backwash operation mode, start the backwash water pump, extract the purified water from the purified water outlet pipe, and backwash the built-in multi-stage filter screen; otherwise, it will maintain normal separation mode.

[0027] After the preset backwashing time, the backwash water pump is turned off, allowing the detached catalyst carrier to re-enter the deep catalytic oxidation section through the differential pressure return pipe under the action of hydraulic eddy current. Subsequently, the system returns to normal separation state.

[0028] Optionally, the control unit also has a built-in state retention program, which includes:

[0029] When the system switches to backwashing operation, the control unit keeps the current opening of the first and second pneumatic actuators unchanged in order to maintain the original gas-liquid countercurrent flow state in the pre-oxidation section and the deep catalytic oxidation section.

[0030] When the catalyst carrier is replenished through the independent carrier replenishment port, the system enters the replenishment waiting state, and the control unit locks the current gas supply distribution ratio of the first gas supply ring pipe and the second gas supply ring pipe.

[0031] Upon receiving the instruction to complete the supplementary task, the system exits the supplementary waiting state and resumes the automatic adjustment program.

[0032] Optionally, the internal filling structure and arrangement of the processing unit include:

[0033] The fluidized bed reactor is covered with a high-temperature resistant ceramic fiber insulation layer with a thickness of 50 to 100 mm to maintain the reaction temperature of 60 to 90°C in the deep catalytic oxidation section by combining the heat of reaction.

[0034] The pre-oxidation section is equipped with a first pre-oxidation catalyst support, which has a particle size of 0.3 to 0.6 mm and a bulk density of 0.8 to 1.2 g / cm³.

[0035] The deep catalytic oxidation section is equipped with a second supported catalyst support, which has a particle size of 0.2 to 0.4 mm and a specific surface area of ​​200 to 500 m² / g.

[0036] Optionally, the processing unit operates in two coordinated phases:

[0037] Pre-oxidation stage: Wastewater flows downward from the inlet distributor and forms a countercurrent contact with the upward-flowing gas in the pre-oxidation section, driving the first pre-oxidation catalyst carrier to form a fluidized state and carry out chain-breaking reactions on the organic matter in the wastewater;

[0038] Deep catalytic oxidation stage: After the chain breaking reaction, the wastewater enters the deep catalytic oxidation section through the first porous grid plate. Driven by the oxidizing gas released from the second gas supply ring pipe, it mixes with the second supported catalyst carrier to achieve deep mineralization of organic matter.

[0039] Optionally, the control unit provides three communication interfaces:

[0040] The monitoring interface is used to receive real-time status electrical signals transmitted from the first organic matter concentration sensor, the second organic matter concentration sensor, the dissolved oxygen sensor, and the differential pressure sensor.

[0041] The control interface is used to send start / stop signals or opening adjustment signals to the first pneumatic actuator, the second pneumatic actuator, the backwash water pump, and the air supply regulating valve.

[0042] The status feedback interface is used to output the residence time percentage, gas supply distribution ratio, and backwash status indicators of each section of the fluidized bed reactor to external devices.

[0043] Optionally, the control unit supports manual parameter modification, and the specific steps include:

[0044] Receive external input operation instructions and parameter modification requests;

[0045] Analyze parameter modification requests and extract updated basic opening settings, adjustment gain coefficients, or backflushing trigger differential pressure thresholds;

[0046] Determine whether the updated parameters are within the preset system security threshold range;

[0047] The configuration is as follows: if the updated parameters are within the preset system safety threshold range, the corresponding parameters in the control unit are updated, and the system's automatic calculation and adjustment actions are restored according to the new parameters. At the same time, a confirmation message of successful parameter update is sent back through the status feedback interface; otherwise, the parameter update is rejected and the original parameters are maintained.

[0048] The beneficial effects of this invention are:

[0049] 1. This invention monitors the dissolved oxygen concentration in the deep catalytic oxidation section in real time through the gas supply ratio control program built into the control unit. When the dissolved oxygen sensor detects that the concentration is lower than the set value, the system controls the gas supply regulating valve to automatically increase the gas supply ratio of the second gas supply ring pipe. This design changes the problem that the traditional system cannot adjust the gas distribution in time when the wastewater load fluctuates. Under the premise of ensuring the basic fluidization conditions of the pre-oxidation section, it prioritizes meeting the high-efficiency reaction requirements of the deep catalytic oxidation section, effectively solving the problem of reduced treatment efficiency caused by insufficient oxidant supply in the deep oxidation zone.

[0050] 2. This invention incorporates a built-in multi-stage filter in the solid-liquid separation section and is equipped with a differential pressure sensor to monitor the internal and external operating pressure difference. When the pressure difference exceeds the limit and meets the duration requirement, the system automatically starts the backwash water pump to extract purified water for reverse flushing. The detached catalyst carrier then re-enters the deep catalytic oxidation section through the differential pressure return pipe under the action of hydraulic eddy current. This solution, without introducing external mechanical conveying equipment, removes the filter blockage in the solid-liquid separation section and executes the catalyst carrier return procedure, extending the continuous operation cycle of the system and improving the stability of the linkage control of each unit. Attached Figure Description

[0051] Other features, objects, and advantages of the invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0052] Figure 1This is a schematic diagram of a multi-stage catalytic fluidized bed treatment system for recalcitrant wastewater provided in an embodiment of the present invention. Detailed Implementation

[0053] 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.

[0054] Please see Figure 1 A multi-stage catalytic fluidized bed treatment system for recalcitrant wastewater includes: a treatment unit that receives recalcitrant wastewater and oxidizing gas, and outputs purified effluent; the treatment unit includes a vertical cylindrical fluidized bed reactor, the interior of which, from top to bottom, consists of a pre-oxidation section, a deep catalytic oxidation section, and a solid-liquid separation section; a first porous grid is provided between the pre-oxidation section and the deep catalytic oxidation section, and a second porous grid is provided between the deep catalytic oxidation section and the solid-liquid separation section; the solid-liquid separation section is provided with a purified effluent pipe, and the side wall of the fluidized bed reactor is provided with an independent carrier replenishment port;

[0055] The feeding unit receives external gas and outputs the distributed oxidizing gas and refluxed catalyst carrier to the processing unit. The feeding unit includes a water inlet distributor located at the top of the pre-oxidation section, a first gas supply ring pipe located at the bottom of the pre-oxidation section, a second gas supply ring pipe located at the bottom of the deep catalytic oxidation section, a differential pressure reflux pipe connected to the side wall of the solid-liquid separation section and communicating with the deep catalytic oxidation section, and a gas supply regulating valve for adjusting the gas supply ratio of the first gas supply ring pipe and the second gas supply ring pipe.

[0056] The monitoring unit includes a first organic matter concentration sensor located at the water inlet distributor, a second organic matter concentration sensor located at the bottom of the pre-oxidation section, a dissolved oxygen sensor located in the deep catalytic oxidation section, and a differential pressure sensor located in the solid-liquid separation section. The monitoring unit is used to generate real-time status signals.

[0057] The execution unit includes a first pneumatic actuator mounted on a first perforated grid plate, a second pneumatic actuator mounted on a second perforated grid plate, and a backwash water pump connected to the purified water outlet pipe;

[0058] The control unit receives real-time status signals, generates adjustment commands, and transmits them to the actuator and the air supply regulating valve.

[0059] The control unit has a built-in residence time control program, which includes: recording the organic matter concentration at the bottom of the pre-oxidation section as measured by the second organic matter concentration sensor, and the organic matter concentration at the inlet water distributor as measured by the first organic matter concentration sensor; and determining whether the measured organic matter concentration at the bottom of the pre-oxidation section is higher than the preset target outlet concentration of the pre-oxidation section.

[0060] The configuration is as follows: If the measured organic matter concentration at the bottom of the pre-oxidation section is higher than the preset target outlet concentration of the pre-oxidation section, then based on the preset adjustment model, the basic opening setting value used to give the default opening benchmark under normal load, and the adjustment gain coefficient used to reflect the amplification of the change in grid opening due to concentration deviation, the through-hole opening of the first porous grid is calculated, and a reduction opening command is generated. The first pneumatic actuator is controlled to execute the reduction opening command to reduce the opening of the first porous grid, increase the hydraulic resistance of the wastewater flowing downward, until the residence time of the pre-oxidation section accounts for 15% to 25% of the total residence time, and the adjustment result is fed back to the control unit; otherwise, the current opening is kept unchanged.

[0061] The adjustment model is configured as follows: based on the deviation between the organic matter concentration at the bottom of the pre-oxidation section and the preset target outlet concentration of the pre-oxidation section, the aperture of the first porous grid plate is negatively compensated and adjusted.

[0062] The control unit has a built-in gas supply ratio control program, which includes recording the dissolved oxygen concentration in the deep catalytic oxidation section as measured by the dissolved oxygen sensor.

[0063] The system determines whether the measured dissolved oxygen concentration is lower than the preset target dissolved oxygen concentration setting value. The configuration is as follows: if the measured dissolved oxygen concentration is lower than the preset target dissolved oxygen concentration setting value, the system calculates the target gas supply ratio of the second gas supply ring pipe according to the gas supply distribution model, generates a gas distribution switching command, controls the gas supply regulating valve to execute the gas distribution switching command, increases the gas supply ratio of the second gas supply ring pipe to determine the remaining gas supply, and distributes the remaining gas supply to the first gas supply ring pipe to enhance the oxidation reaction of the deep catalytic oxidation section, and feeds back the distribution status to the control unit.

[0064] Otherwise, the current gas supply ratio remains unchanged; the gas supply allocation model is configured as follows: based on the measured dissolved oxygen concentration and the deficit relationship between the target dissolved oxygen concentration setting, the gas supply allocated to the second gas supply ring is dynamically calculated and increased.

[0065] In this embodiment, the recalcitrant wastewater enters the vertical cylindrical fluidized bed reactor through the inlet distributor and passes through the pre-oxidation section, the deep catalytic oxidation section, and the solid-liquid separation section from top to bottom.

[0066] Oxidizing gas is fed from bottom to top through the first gas supply ring pipe and the second gas supply ring pipe respectively, so that the wastewater and the catalyst carrier form countercurrent contact in different sections;

[0067] The treated purified water is discharged through the purified water pipe, and the retained catalyst carrier re-enters the deep catalytic oxidation section under the action of the differential pressure return pipe to continue to participate in the reaction;

[0068] By using this arrangement to complete segmented reaction and solid-liquid separation within a single reactor, it is possible to perform chain breaking and then mineralization of recalcitrant organic matter without employing a dual-tower series structure.

[0069] The reactor obtains recalcitrant wastewater and an external gas source. Based on the upper reaction space (pre-oxidation section) for primary oxidation and chain breaking, the middle reaction space (deep catalytic oxidation section) for deep mineralization, and the lower space (solid-liquid separation section) for intercepting the catalytic carrier and outputting purified effluent, the recalcitrant wastewater is subjected to segmented catalytic treatment to generate purified effluent and reflux catalytic carrier.

[0070] This invention enables pre-oxidation, deep oxidation, and separation and recovery to be completed continuously within the same equipment by setting up a partitioned structure, a two-stage gas supply structure, and a reflux structure inside the same fluidized bed reactor, thus achieving a compact and direct processing method.

[0071] Furthermore, based on the above embodiments, the processing unit specifically adopts a vertical cylindrical fluidized bed reactor; inside the reactor, a first porous grid is provided between the pre-oxidation section and the deep catalytic oxidation section, and a second porous grid is provided between the deep catalytic oxidation section and the solid-liquid separation section.

[0072] The two perforated grid plates not only serve to separate sections, but also directly participate in the allocation of dwell time;

[0073] The inlet distributor is located at the top of the pre-oxidation section to allow wastewater to enter the upper reaction zone; the first gas supply ring is located at the bottom of the pre-oxidation section to supply oxidizing gas upwards to fluidize the catalyst carrier; the second gas supply ring is located at the bottom of the deep catalytic oxidation section to supply gas upwards, accounting for a portion of the total gas supply. to Oxidizing gases;

[0074] The solid-liquid separation section is equipped with a purified water outlet pipe and a differential pressure return pipe. The former discharges the purified water, while the latter sends the catalytic carrier accumulated after separation back to the deep catalytic oxidation section. The side wall of the reactor is equipped with an independent carrier replenishment port for replenishing or replacing the catalytic carrier.

[0075] The online detection results reflecting the internal operation of the processing unit, output by the first organic matter concentration sensor, the second organic matter concentration sensor, the dissolved oxygen sensor, and the differential pressure sensor, are obtained as real-time status signals. Based on the calculation results of the control unit, the first pneumatic actuator, the second pneumatic actuator, the backwash water pump, and the air supply regulating valve are adjusted to generate corresponding structural actions and air supply distribution results, such as changing the opening of the porous grid or performing backwashing.

[0076] This invention enables the resistance and gas volume distribution in different sections to be adaptively adjusted according to the processing status by directly linking online monitoring and execution components.

[0077] Furthermore, based on the above embodiments, the control unit has a built-in residence time control program; this program is used to adjust the opening of the through holes of the first porous grid plate according to the change in organic matter concentration at the outlet of the pre-oxidation section, thereby changing the hydraulic resistance when the wastewater flows from the pre-oxidation section to the deep catalytic oxidation section.

[0078] By configuring the aperture of the first porous grid plate, the residence time of the pre-oxidation section is controlled, so that the wastewater can undergo chain breaking reaction and then enter the subsequent deep catalytic oxidation section.

[0079] The organic matter concentration at the bottom of the pre-oxidation section, measured by the second organic matter concentration sensor, after the wastewater passes through the pre-oxidation section and before entering the first porous grid plate, and the initial concentration of the wastewater when it enters the reactor, i.e., the influent organic matter concentration at the influent distributor, measured by the first organic matter concentration sensor, are obtained. Based on the control benchmark used to determine whether the pre-oxidation is sufficient, i.e., the preset target outlet concentration of the pre-oxidation section, the opening degree of the through holes of the first porous grid plate is calculated, and a command to reduce the opening degree or a result to keep the opening degree unchanged is generated.

[0080] This invention utilizes the synergistic effect of concentration feedback and adjustable opening degree to enable the resistance distribution to be adjusted according to changes in wastewater load;

[0081] In practical implementation, the percentage of the opening of the first porous grid is calculated according to the following relationship: the percentage of the opening of the first porous grid is equal to the basic opening setting value used to give the default opening benchmark under normal load, minus the product of the adjustment gain coefficient used to reflect the amplification of the grid opening change due to concentration deviation and the concentration difference ratio. The concentration difference ratio is the difference between the measured organic matter concentration at the bottom of the pre-oxidation section and the preset target outlet concentration of the pre-oxidation section divided by the influent organic matter concentration.

[0082] When the measured organic matter concentration at the bottom of the pre-oxidation section is higher than the preset target outlet concentration of the pre-oxidation section, the above difference is positive, the calculated opening is reduced, and the first pneumatic actuator reduces the through-hole area of ​​the first porous grid plate accordingly, thereby increasing the hydraulic resistance of the wastewater flowing downward until the residence time of the pre-oxidation section accounts for 15% to 25% of the total residence time; when the measured concentration is not higher than the target value, the current opening is kept unchanged.

[0083] In one specific embodiment, when the concentration of organic matter in the influent is The preset target outlet concentration of the pre-oxidation section is If the current organic matter concentration sensor measures the organic matter concentration at the bottom of the pre-oxidation section to be... ;

[0084] Based on the aforementioned relationship, the concentration difference ratio is: Substituting the base opening setting of 60% and the adjustment gain coefficient of 0.8, the calculation yields:

[0085]

[0086] The first pneumatic actuator reduces the opening from 60% to 52%, thereby effectively increasing the resistance to the downward flow of water and extending the residence time of wastewater in the pre-oxidation section.

[0087] In this embodiment, the residence time of the deep catalytic oxidation stage can account for 60% to 75% of the total residence time; this distribution corresponds to the reaction characteristics of recalcitrant organic compounds, which first undergo chain scission and then oxidation.

[0088] The residence time of the upper section is adjusted by using the first porous grid plate, and then the residence time of the lower section, which accounts for 60% to 75% of the total residence time, is used to complete the deep mineralization, so that the load distribution of the two-stage reaction is clear.

[0089] Furthermore, based on the above embodiments, the control unit has a built-in gas supply ratio control program; according to the change in dissolved oxygen concentration in the deep catalytic oxidation section, the gas supply ratio of the first gas supply ring and the second gas supply ring is redistributed under the condition that the total gas supply of the system is constant.

[0090] The oxidant is supplied to the deep catalytic oxidation section by configuring the gas supply ratio of the second gas supply ring, and the flow conditions of the pre-oxidation section are maintained.

[0091] The invention obtains the online detection value of dissolved oxygen concentration in the deep catalytic oxidation section, which reflects the sufficiency of oxidant in the deep mineralization reaction zone, as measured by a dissolved oxygen sensor. Based on the dissolved oxygen benchmark required to maintain the high-activity reaction in the deep catalytic oxidation section, i.e., the preset target dissolved oxygen concentration setting value, the target gas supply ratio of the second gas supply loop is calculated, and a gas distribution switching command or a result of maintaining the current gas supply ratio is generated. The invention uses a gas supply distribution model based on dissolved oxygen deficiency to prioritize the distribution of oxidizing gas to the deep catalytic oxidation section.

[0092] In practical implementation, the gas supply allocated to the second gas supply ring is calculated according to the following relationship:

[0093]

[0094]

[0095]

[0096] When the measured dissolved oxygen in the deep catalytic oxidation section is lower than the target value, the dissolved oxygen deficit rate is positive, and the allocation coefficient increases from the base value of 0.65, so that the second gas supply ring pipe receives more gas.

[0097] The upper limit of the gas supply ratio of the second gas supply ring is set to 80% of the total gas supply of the system. The remaining 20% ​​to 35% of the total gas supply of the system is allocated to the first gas supply ring to maintain the fluidization state of the pre-oxidation section.

[0098] Specifically, when the load fluctuation of recalcitrant wastewater exceeds the system's safety threshold range, if a fixed gas ratio is still used, it often cannot reflect the actual oxygen consumption changes in the deep catalytic oxidation section in a timely manner, which can easily lead to problems such as insufficient oxidant and decreased mineralization efficiency in the deep catalytic oxidation section.

[0099] This embodiment continuously provides the status of the deep catalytic oxidation section through a dissolved oxygen sensor. The gas supply regulating valve redistributes the gas volume according to the calculation results, so that the second gas supply ring pipe accounts for 65% of the total gas volume in the basic state, and continues to increase the proportion when dissolved oxygen is insufficient, thereby maintaining the reaction conditions of the deep catalytic oxidation section within the preset target range.

[0100] In one specific embodiment, the total gas supply of the system is set to a stable value. The preset target dissolved oxygen concentration is set to ;

[0101] At a certain high-load impact moment, the dissolved oxygen sensor measured the dissolved oxygen concentration in the deep catalytic oxidation section to drop to... ;

[0102] At this point, the control program calculates the dissolved oxygen deficit rate as 1 - (3.2 / 4.0) = 0.2; correspondingly... The target gas supply volume allocated to the second gas supply ring pipe is 100 × 0.68 = 68 m³ / h, which accounts for 68% of the total gas volume. The remaining 32 m³ / h is automatically allocated to the first gas supply ring pipe.

[0103] By adjusting the opening of the first porous grid and the two-stage air supply ratio, the wastewater can first undergo pre-oxidation and chain breaking in the same reactor, and then undergo deep catalytic oxidation. The purified water is discharged from the bottom, while the catalyst carrier is retained in the system for continued recycling.

[0104] In a preferred embodiment of the present invention, a built-in multi-stage filter is provided in the solid-liquid separation section; the system has a normal separation state and a backwashing operation state, and its state switching and execution process includes: in the normal separation state, recording the operating pressure difference between the inner and outer sides of the built-in multi-stage filter as monitored in real time by the differential pressure sensor; determining whether the operating pressure difference is greater than or equal to a preset backwashing trigger pressure difference threshold to form an over-limit state, and determining whether the duration of the over-limit state exceeds a preset duration threshold;

[0105] The configuration is as follows: if the operating differential pressure is greater than or equal to the backwash trigger differential pressure threshold and the duration exceeds the preset duration threshold, the system will automatically switch to backwash operation state, start the backwash water pump, draw the purified water from the purified water outlet pipe, and backwash the built-in multi-stage filter screen.

[0106] Otherwise, maintain normal separation; after the preset backwash time, turn off the backwash water pump, so that the detached catalyst carrier can re-enter the deep catalytic oxidation section through the pressure difference return pipe under the action of hydraulic eddy current, and the system returns to normal separation.

[0107] The control unit also has a built-in state holding program, which includes: when the system switches to backwash operation, the control unit keeps the current opening degree of the first pneumatic actuator and the second pneumatic actuator unchanged, so as to maintain the original gas-liquid countercurrent flow state in the pre-oxidation section and the deep catalytic oxidation section;

[0108] When the catalyst carrier is replenished through the independent carrier replenishment port, the system enters a replenishment waiting state, and the control unit locks the current gas supply distribution ratio of the first gas supply ring pipe and the second gas supply ring pipe; after receiving the replenishment operation completion instruction, the system exits the replenishment waiting state and resumes the automatic adjustment program.

[0109] In this embodiment, the solid-liquid separation section uses a built-in multi-stage filter to intercept the catalyst carrier that enters the lower region with the water flow, and the purified water is discharged through the purified water outlet pipe.

[0110] When the operating pressure difference across the filter screen continues to rise to the set range, the system automatically switches to backwash operation mode, and the backwash water pump draws purified water to backwash the built-in multi-stage filter screen.

[0111] After backwashing, the detached catalyst support is re-entered into the deep catalytic oxidation section by means of hydraulic eddy current and differential pressure return pipe; in this way, filter cleaning and catalyst support recovery can be completed without the need for external mechanical conveying equipment.

[0112] The system obtains the operating pressure difference changes between the inner and outer sides of the built-in multi-stage filter screen, which are formed by the accumulation of catalyst carrier and the increase of fluid resistance on both sides of the filter screen in real time by the differential pressure sensor. Based on the differential pressure benchmark used to determine whether the filter screen needs to be cleaned, namely the backwash trigger differential pressure threshold and the time benchmark that needs to be maintained after the differential pressure exceeds the limit, namely the preset duration threshold, the system operating status is judged and a normal separation state or backwash operating state is generated.

[0113] This invention uses both differential pressure and duration as criteria to initiate backwashing only when the differential pressure reaches a threshold and continues to exceed it.

[0114] Furthermore, based on the above embodiments, when the system is in a normal separation state, the differential pressure sensor continuously records the operating pressure difference on both sides of the built-in multi-stage filter.

[0115] If the detected operating differential pressure is greater than or equal to the backwash trigger differential pressure threshold, and the duration of this over-limit state exceeds the preset duration threshold, the control unit issues a switching command to automatically switch the system to backwash operation state; if the above two conditions are not met at the same time, the system remains in normal separation state.

[0116] The purified water is obtained from the purified water outlet pipe. According to the backwash command issued by the control unit, the backwash water pump uses the purified water to form a water flow opposite to the normal filtration direction to impact and peel off the catalyst carrier and attachments accumulated on the surface of the built-in multi-stage filter screen. This causes the catalyst carrier that has been removed from the filter screen to form a suspended state in the solid-liquid separation section and re-enter the deep catalytic oxidation section through the pressure difference return pipe under the action of hydraulic eddy current, thereby generating the reflux result of the peeled catalyst carrier.

[0117] This invention enables the carrier to be separated, peeled off, and recirculated inside the equipment through the combination of a built-in multi-stage filter, a backwash water pump, and a differential pressure return pipe.

[0118] In practice, the backwash pump is turned off after a preset backwash time; the backwash time is set to 5 to 15 minutes, preferably 10 minutes.

[0119] Configure the backwashing time to allow the catalyst carrier attached to the surface of the built-in multi-stage filter to detach and maintain the preset system operating cycle;

[0120] After backwashing, the detached catalyst support enters the differential pressure return pipe in the solid-liquid separation section under the action of hydraulic eddy current, and re-enters the deep catalytic oxidation section to continue participating in the reaction; the catalyst support separated and re-entering the deep catalytic oxidation section after backwashing is maintained above the preset recovery threshold standard.

[0121] Furthermore, based on the above embodiments, the control unit also has a built-in state maintenance program; this program does not change the backwash judgment conditions, but keeps the original operating conditions of the pre-oxidation section and the deep catalytic oxidation section within the preset parameter range during the state switching process.

[0122] During backwashing operation, the predetermined flow parameters of the pre-oxidation section and the deep catalytic oxidation section are maintained by locking the current set values ​​of the grid opening and the gas supply ratio.

[0123] The system acquires the status signal of switching to backwashing operation. According to the status holding program, the actual orifice opening of the first and second pneumatic actuators before the switch is maintained, i.e., the current opening. This generates the result of maintaining the existing flow relationship between wastewater from top to bottom and oxidizing gas from bottom to top in the two reaction sections, i.e., the original gas-liquid countercurrent flow state of the pre-oxidation section and the deep catalytic oxidation section.

[0124] This invention maintains the opening of the two porous grid plates unchanged during backwashing, so that the backwashing action is concentrated only in the separation section, reducing the impact on the two upper reaction sections.

[0125] The system acquires the operation signal for catalyst carrier replenishment through the independent carrier replenishment port. According to the state holding procedure, the system enters a temporary holding state, i.e., a replenishment waiting state, when replenishing or replacing the catalyst carrier. The system also maintains the ratio of the two-stage gas supply that was established at the start of replenishment and does not change automatically, i.e., it locks the current gas supply distribution ratio of the first and second gas supply rings, and generates a stable gas supply result during the replenishment operation.

[0126] This invention locks the current gas supply ratio during the supplementary operation, and exits the supplementary waiting state and resumes the automatic adjustment program after receiving the instruction to complete the supplementary operation.

[0127] This implementation method establishes a stable operating mechanism for the solid-liquid separation section through differential pressure-triggered backwashing, purified effluent reverse flushing, differential pressure return pipe for catalyst carrier recovery, and state maintenance procedures. This enables filter cleaning, carrier recovery, and flow state maintenance in the pre-oxidation and deep catalytic oxidation sections to be carried out in a coordinated manner.

[0128] In a preferred embodiment of the present invention, the internal filling structure and arrangement of the processing unit include: the fluidized bed reactor is covered with a high-temperature resistant ceramic fiber insulation layer with a thickness of 50 to 100 mm, which is used to maintain a reaction temperature of 60 to 90°C in the deep catalytic oxidation section by combining the heat of reaction.

[0129] The pre-oxidation section is equipped with a first pre-oxidation catalyst support, which has a particle size of 0.3 to 0.6 mm and a bulk density of 0.8 to 1.2 g / cm³.

[0130] The deep catalytic oxidation section is equipped with a second supported catalyst support, which has a particle size of 0.2 to 0.4 mm and a specific surface area of ​​200 to 500 m² / g.

[0131] The treatment unit operates in two synergistic stages: Pre-oxidation stage: Wastewater flows downward from the inlet distributor and forms a countercurrent contact with the upward-flowing gas in the pre-oxidation section, driving the first pre-oxidation catalyst carrier to form a fluidized state and carrying out chain-breaking reactions on the organic matter in the wastewater;

[0132] Deep catalytic oxidation stage: After the chain breaking reaction, the wastewater enters the deep catalytic oxidation section through the first porous grid plate. Driven by the oxidizing gas released from the second gas supply ring pipe, it mixes with the second supported catalyst carrier to achieve deep mineralization of organic matter.

[0133] The control unit provides three communication interfaces: a monitoring interface, used to receive real-time status electrical signals transmitted by the first organic matter concentration sensor, the second organic matter concentration sensor, the dissolved oxygen sensor, and the differential pressure sensor;

[0134] The control interface is used to send start / stop signals or opening adjustment signals to the first pneumatic actuator, the second pneumatic actuator, the backwash water pump, and the air supply regulating valve.

[0135] The status feedback interface is used to output the residence time percentage, gas supply distribution ratio, and backwash status indicators of each section of the fluidized bed reactor to external devices.

[0136] The control unit supports manual parameter modification. The specific execution steps include: receiving external input operation instructions and parameter modification requests; parsing the parameter modification requests, extracting the updated basic opening setting value, adjusting the gain coefficient or backwash trigger differential pressure threshold; and determining whether the updated parameters are within the preset system safety threshold range.

[0137] The configuration is as follows: if the updated parameters are within the preset system safety threshold range, the corresponding parameters in the control unit are updated, and the system's automatic calculation and adjustment actions are restored according to the new parameters. At the same time, a confirmation message of successful parameter update is sent back through the status feedback interface; otherwise, the parameter update is rejected and the original parameters are maintained.

[0138] In this embodiment, the internal packing structure and operation mode of the fluidized bed reactor are coordinated with each other; the pre-oxidation section is filled with the first pre-oxidation catalyst support, which is used to complete the chain breaking reaction of organic matter;

[0139] The deep catalytic oxidation section is filled with a second supported catalyst carrier to complete deep mineralization; the reactor is covered with a high-temperature resistant ceramic fiber insulation layer to maintain the temperature required for the deep catalytic oxidation section in conjunction with the heat of reaction.

[0140] The control unit receives sensor signals through the monitoring interface, sends adjustment signals to the execution unit and the feeding unit through the control interface, and outputs the operating results to external devices through the status feedback interface.

[0141] When needed, external devices can also send parameter modification requests to the control unit to adjust the basic opening setting, adjustment gain coefficient, or backwash trigger differential pressure threshold.

[0142] The external insulation requirements and internal reaction requirements of the fluidized bed reactor were obtained. Based on the temperature maintenance conditions of the deep catalytic oxidation section, a high-temperature resistant ceramic fiber insulation structure with a thickness of 50 to 100 mm was applied to the outside of the fluidized bed reactor, i.e., a high-temperature resistant ceramic fiber insulation layer. A first pre-oxidation catalytic support with a particle size of 0.3 to 0.6 mm and a bulk density of 0.8 to 1.2 g / cm³ was set in the pre-oxidation section, and a second supported catalytic support with a particle size of 0.2 to 0.4 mm and a specific surface area of ​​200 to 500 m² / g was set in the deep catalytic oxidation section, thereby generating an internal filling structure suitable for segmented reactions.

[0143] This invention uses segmented catalytic supports with different properties and utilizes a heat insulation layer combined with the heat of reaction to maintain a reaction temperature of 60 to 90°C in the deep catalytic oxidation section, so that the performance of the support matches the reaction task.

[0144] Furthermore, the first pre-oxidation catalyst support in the pre-oxidation section adopts a packing density of 0.8 to 1.2 g / cm³, and is formed and maintained in a fluidized state under the drive of the rising airflow formed by the first gas supply ring pipe, so as to construct the contact interface between wastewater and the first pre-oxidation catalyst support.

[0145] The second supported catalyst in the deep catalytic oxidation section uses a particle size of 0.2 to 0.4 mm and a specific surface area of ​​200 to 500 m² / g to configure a catalytic specific surface area suitable for deep mineralization reactions.

[0146] The combined effect of the external high-temperature resistant ceramic fiber insulation layer and the heat released by the oxidation reaction of organic matter can maintain the reaction temperature of 60 to 90°C in the deep catalytic oxidation section without the need for an independent external heating element.

[0147] Wastewater entering through the inlet distributor is collected. Based on the gas-liquid countercurrent contact conditions in the two sections, the wastewater undergoes a pre-oxidation stage where it comes into countercurrent contact with gas from bottom to top to drive the first pre-oxidation catalyst carrier to form a fluidized state and perform chain-breaking reactions on organic matter. After the chain-breaking reaction, the wastewater enters the deep catalytic oxidation stage through the first porous grid plate and is mixed with the second supported catalyst carrier under the drive of the oxidizing gas released from the second gas supply ring pipe to achieve deep mineralization of organic matter. This process generates wastewater after the chain-breaking reaction and the final purified effluent.

[0148] This invention transforms indiscriminate processing into sequential processing by setting up two collaborative stages, with the first stage focusing on chain breaking and the second stage focusing on mineralization.

[0149] Furthermore, based on the above embodiments, wastewater flows downward from the inlet water distributor, and the first air supply ring pipe and the second air supply ring pipe release oxidizing gas from bottom to top respectively.

[0150] Due to the different carrier properties of the pre-oxidation section and the deep catalytic oxidation section, the two fluidization states also have different functions: the former mainly promotes the chain scission of macromolecular organic matter, while the latter mainly promotes the deep mineralization of organic matter after chain scission.

[0151] By setting the first porous grid, the wastewater has completed the pre-oxidation treatment before entering the deep catalytic oxidation section, thereby reducing the treatment load of the subsequent deep catalytic oxidation section; by providing 65% to 80% of the total gas supply through the second gas supply ring pipe, the lower section can maintain the preset target dissolved oxygen level.

[0152] The system acquires real-time status electrical signals transmitted by the first organic matter concentration sensor, the second organic matter concentration sensor, the dissolved oxygen sensor, and the differential pressure sensor. Based on the interface settings of the control unit, it receives the real-time status electrical signals, sends control signals, and outputs status information. It generates monitoring interfaces for the control unit to receive real-time status electrical signals from each sensor, control interfaces for the control unit to send start / stop signals or opening adjustment signals to the first pneumatic actuator, the second pneumatic actuator, the backwash water pump, and the air supply regulating valve, and external communication results for the status feedback interface that outputs the residence time ratio of each section, the air supply distribution ratio, and the backwash status indicator to external devices.

[0153] This invention enables independent transmission of information through the clear division of labor among three types of communication interfaces, namely monitoring, regulation, and feedback.

[0154] Furthermore, based on the above embodiments, the residence time percentage, air supply distribution ratio, and backwash status indicator output by the status feedback interface are all directly derived from the current adjustment results of the control unit.

[0155] Among them, the residence time ratio reflects the distribution of the pre-oxidation section and the deep catalytic oxidation section in the total residence time; the gas supply distribution ratio reflects the current gas volume ratio between the first gas supply ring and the second gas supply ring.

[0156] The backwash status indicator reflects whether the system is currently in normal separation or backwash operation; this output can be read by external devices to understand the current processing status of the system.

[0157] The system acquires external input operation instructions and parameter modification requests. Based on the range that allows the system to maintain safe operation after parameter modification, i.e., the preset system safety threshold range, it updates the initial benchmark value (i.e., the basic opening setting value) in the calculation of the opening of the first porous grid plate, the coefficient of the influence of the concentration difference ratio on the opening of the opening (i.e., the adjustment gain coefficient), or the differential pressure benchmark (i.e., the backwash trigger differential pressure threshold) for determining whether backwashing is required. The system then generates a confirmation message of successful parameter update or a result of rejection of update.

[0158] This invention provides boundary constraints for parameter modification by first parsing the request and then determining whether it falls within a preset safety threshold range.

[0159] In practice, after receiving the operation command and parameter modification request from the external input, the control unit first parses the request and extracts the updated basic opening setting value, adjustment gain coefficient or backwash trigger differential pressure threshold.

[0160] If the updated parameters are within the preset system safety threshold range, the control unit updates the corresponding parameters and resumes automatic calculation and adjustment actions according to the new parameters. At the same time, it sends out confirmation information that the parameter update was successful through the status feedback interface.

[0161] If the updated parameter is not within the preset system safety threshold range, the parameter update will be rejected and the original parameter will be maintained. The automatic calculation and adjustment action here corresponds to the aforementioned residence time control program, gas supply ratio control program and backwash trigger logic continuing to execute according to the new parameter value.

[0162] To further clarify the system safety constraints when modifying parameters, the preset system safety threshold range can be specifically set as follows: the safety range of the basic opening setting value is 40% to 80%, to prevent the reactor from overflowing due to excessively small opening or losing its interception function due to excessively large opening.

[0163] The safe range for adjusting the gain coefficient is 0.5 to 1.2 to avoid response lag or system divergence oscillation; the safe range for the backflushing trigger differential pressure threshold is... to This is to ensure that the filter screen does not fail mechanically due to excessive pressure differential;

[0164] For example, if the operator attempts to modify the backwash trigger differential pressure threshold using external equipment... The control unit, after analysis, determined that it exceeded the limit. If the safety limit is not within the preset system safety threshold range, the update will be rejected and the original parameters will be maintained to keep the system running within the preset safety pressure threshold.

[0165] In application examples, the multi-stage catalytic fluidized bed treatment system of the present invention can be directly deployed at the site of recalcitrant wastewater treatment;

[0166] During operation, new recalcitrant wastewater enters the pre-oxidation section from the inlet distributor, and new external air source enters the first and second air supply ring pipes after being distributed by the air supply regulating valve.

[0167] The first organic matter concentration sensor, the second organic matter concentration sensor, the dissolved oxygen sensor, and the differential pressure sensor continuously transmit real-time status electrical signals to the monitoring interface. Based on these signals, the control unit calculates the opening degree of the first porous grid plate, the air supply ratio of the second air supply ring pipe, and whether the backwashing operation state has been entered. The control unit then sends corresponding signals to the first pneumatic actuator, the second pneumatic actuator, the backwash water pump, and the air supply regulating valve via the control interface.

[0168] External devices can read the percentage of dwell time in each section, the gas supply distribution ratio, and the backwash status indicator through the status feedback interface, and input parameter modification requests when necessary;

[0169] Therefore, the system can continuously complete the staged degradation of wastewater, solid-liquid separation, catalytic carrier reflux, and operation status feedback during actual operation.

[0170] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A multi-stage catalytic fluidized bed treatment system for recalcitrant wastewater, characterized in that, include: The treatment unit receives recalcitrant wastewater and oxidizing gases, and outputs purified effluent. The treatment unit includes a vertical cylindrical fluidized bed reactor. The fluidized bed reactor contains, from top to bottom, a pre-oxidation section, a deep catalytic oxidation section, and a solid-liquid separation section. A first porous grid is provided between the pre-oxidation section and the deep catalytic oxidation section, and a second porous grid is provided between the deep catalytic oxidation section and the solid-liquid separation section. The solid-liquid separation section is equipped with a purified effluent pipe, and the side wall of the fluidized bed reactor has an independent carrier replenishment port. The feeding unit receives external gas and outputs the distributed oxidizing gas and reflux catalyst carrier to the processing unit; the feeding unit includes a water inlet distributor located at the top of the pre-oxidation section, a first gas supply ring pipe located at the bottom of the pre-oxidation section, a second gas supply ring pipe located at the bottom of the deep catalytic oxidation section, a differential pressure reflux pipe connected to the side wall of the solid-liquid separation section and communicating with the deep catalytic oxidation section, and a gas supply regulating valve for adjusting the gas supply ratio of the first gas supply ring pipe and the second gas supply ring pipe. The monitoring unit includes a first organic matter concentration sensor located at the water inlet distributor, a second organic matter concentration sensor located at the bottom of the pre-oxidation section, a dissolved oxygen sensor located in the deep catalytic oxidation section, and a differential pressure sensor located in the solid-liquid separation section. The monitoring unit is used to generate real-time status signals. The execution unit includes a first pneumatic actuator mounted on the first porous grid plate, a second pneumatic actuator mounted on the second porous grid plate, and a backwash water pump connected to the purified water outlet pipe; The control unit receives the real-time status signal, generates adjustment commands, and transmits them to the execution unit and the gas supply regulating valve.

2. The multi-stage catalytic fluidized bed treatment system for recalcitrant wastewater according to claim 1, characterized in that, The control unit has a built-in dwell time control program, which includes: Record the organic matter concentration at the bottom of the pre-oxidation section as measured by the second organic matter concentration sensor, and the organic matter concentration at the inlet water distributor as measured by the first organic matter concentration sensor; Determine whether the measured organic matter concentration at the bottom of the pre-oxidation section is higher than the preset target outlet concentration of the pre-oxidation section; The configuration is as follows: if the measured organic matter concentration at the bottom of the pre-oxidation section is higher than the preset target outlet concentration of the pre-oxidation section, then based on the preset adjustment model, the basic opening setting value used to give the default opening benchmark under normal load, and the adjustment gain coefficient used to reflect the amplification of the change in grid opening due to concentration deviation, the through-hole opening of the first porous grid is calculated, and a reduction opening command is generated. The first pneumatic actuator is controlled to execute the reduction opening command to reduce the opening of the first porous grid, increase the hydraulic resistance of the wastewater flowing downward, until the residence time of the pre-oxidation section accounts for 15% to 25% of the total residence time, and the adjustment result is fed back to the control unit; otherwise, the current opening is kept unchanged. The adjustment model is configured to: negatively compensate and adjust the aperture of the first porous grid plate based on the deviation between the organic matter concentration at the bottom of the pre-oxidation section and the preset target outlet concentration of the pre-oxidation section.

3. The multi-stage catalytic fluidized bed treatment system for recalcitrant wastewater according to claim 1, characterized in that, The control unit has a built-in gas supply ratio control program, which includes: Record the dissolved oxygen concentration within the deep catalytic oxidation section as measured by the dissolved oxygen sensor; Determine whether the measured dissolved oxygen concentration is lower than the preset target dissolved oxygen concentration setting value; The configuration is as follows: if the measured dissolved oxygen concentration is lower than the preset target dissolved oxygen concentration setting value, the target gas supply ratio of the second gas supply loop is calculated according to the gas supply distribution model, and a gas distribution switching command is generated. The gas supply regulating valve is controlled to execute the gas distribution switching command, increase the gas supply ratio of the second gas supply loop to determine the remaining gas supply, and allocate the remaining gas supply to the first gas supply loop to enhance the oxidation reaction of the deep catalytic oxidation section. The distribution status is then fed back to the control unit. Otherwise, the current gas supply ratio remains unchanged. The gas supply allocation model is configured to dynamically calculate and increase the gas supply allocated to the second gas supply ring pipe based on the difference between the measured dissolved oxygen concentration and the target dissolved oxygen concentration setting value.

4. The multi-stage catalytic fluidized bed treatment system for recalcitrant wastewater according to claim 1, characterized in that, The solid-liquid separation section is equipped with a built-in multi-stage filter screen; The system has a normal separation state and a backwashing operation state, and its state switching and execution process includes: Under the normal separation state, the operating pressure difference between the inner and outer sides of the built-in multi-stage filter, as monitored in real time by the differential pressure sensor, is recorded. Determine whether the operating differential pressure is greater than or equal to a preset backflushing trigger differential pressure threshold to form an over-limit state, and determine whether the duration of the over-limit state exceeds a preset duration threshold. The system is configured such that if the operating differential pressure is greater than or equal to the backwash trigger differential pressure threshold and the duration exceeds the preset duration threshold, the system automatically switches to the backwash operation state, starts the backwash water pump, draws the purified water from the purified water outlet pipe, and backwashes the built-in multi-stage filter; otherwise, it maintains the normal separation state. After a preset backwashing time, the backwash water pump is turned off, allowing the detached catalyst carrier to re-enter the deep catalytic oxidation section via the differential pressure return pipe under the action of hydraulic eddy current. Subsequently, the system returns to the normal separation state.

5. The multi-stage catalytic fluidized bed treatment system for recalcitrant wastewater according to claim 4, characterized in that, The control unit also has a built-in state retention program, which includes: When the system switches to the backwashing operation state, the control unit keeps the current opening degree of the first pneumatic actuator and the second pneumatic actuator unchanged, so as to maintain the original gas-liquid countercurrent flow state in the pre-oxidation section and the deep catalytic oxidation section; When the catalyst carrier is replenished through the independent carrier replenishment port, the system enters a replenishment waiting state, and the control unit locks the current gas supply distribution ratio of the first gas supply ring pipe and the second gas supply ring pipe. Upon receiving the instruction to complete the supplementary task, the system exits the supplementary waiting state and resumes the automatic adjustment program.

6. The multi-stage catalytic fluidized bed treatment system for recalcitrant wastewater according to claim 1, characterized in that, The internal filling structure and arrangement of the processing unit include: The fluidized bed reactor is covered with a high-temperature resistant ceramic fiber insulation layer with a thickness of 50 to 100 mm, which is used to maintain the reaction temperature of 60 to 90°C in the deep catalytic oxidation section by combining the heat of reaction. The pre-oxidation section is provided with a first pre-oxidation catalyst support, the first pre-oxidation catalyst support having a particle size of 0.3 to 0.6 mm and a bulk density of 0.8 to 1.2 g / cm³; The deep catalytic oxidation section is provided with a second supported catalytic support, the second supported catalytic support having a particle size of 0.2 to 0.4 mm and a specific surface area of ​​200 to 500 m² / g.

7. The multi-stage catalytic fluidized bed treatment system for recalcitrant wastewater according to claim 6, characterized in that, The processing unit operates in two collaborative phases: Pre-oxidation stage: Wastewater flows downward from the inlet distributor and forms a countercurrent contact with the gas flowing upward in the pre-oxidation section, driving the first pre-oxidation catalyst carrier to form a fluidized state and carry out chain-breaking reaction on the organic matter in the wastewater; Deep catalytic oxidation stage: After the chain breaking reaction, the wastewater enters the deep catalytic oxidation section through the first porous grid plate. Driven by the oxidizing gas released from the second gas supply ring pipe, it mixes with the second supported catalyst carrier to achieve deep mineralization of organic matter.

8. The multi-stage catalytic fluidized bed treatment system for recalcitrant wastewater according to claim 1, characterized in that, The control unit provides three communication interfaces: The monitoring interface is used to receive real-time status electrical signals transmitted by the first organic matter concentration sensor, the second organic matter concentration sensor, the dissolved oxygen sensor, and the differential pressure sensor; The control interface is used to send start / stop signals or opening adjustment signals to the first pneumatic actuator, the second pneumatic actuator, the backwash water pump, and the air supply regulating valve. The status feedback interface is used to output the residence time percentage, gas supply distribution ratio, and backwash status indicator of each section of the fluidized bed reactor to external devices.

9. A multi-stage catalytic fluidized bed treatment system for recalcitrant wastewater according to claim 8, characterized in that, The control unit supports manual parameter modification, and the specific execution steps include: Receive external input operation instructions and parameter modification requests; Parse the parameter modification request and extract the updated basic opening setting value, adjustment gain coefficient, or backwash trigger differential pressure threshold; Determine whether the updated parameters are within the preset system security threshold range; The configuration is as follows: if the updated parameters are within the preset system safety threshold range, the corresponding parameters in the control unit are updated, and the system's automatic calculation and adjustment actions are restored according to the new parameters. At the same time, a confirmation message of successful parameter update is fed back through the status feedback interface; otherwise, the parameter update is rejected and the original parameters are maintained.

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