Plug flow type aeration device coupling gradually-decreasing aeration and mechanical stirring

Abstract

The invention relates to the technical field of sewage treatment, and discloses a gradually-decreasing aeration and mechanical stirring coupled plug-flow type aeration device which comprises a plug-flow type aeration device body, an air distribution main pipe and aeration branch pipes are installed in the plug-flow type aeration device body, and the installation density of the aeration branch pipes is gradually decreased along the way of the plug-flow type aeration device body; the air blower is connected with the air distribution main pipe; the gas flow meter is mounted on the gas distribution main pipe; the microporous aerators are mounted on the aeration branch pipes; and the stirring system is mounted at the middle-rear section of the aeration tank with insufficient aeration stirring effect, and is used for enhancing the stirring effect to keep the activated sludge mixed liquid in a suspended state and enhancing the oxygen mass transfer efficiency. According to the present invention, the aeration rate is accurately controlled through the gradually-reduced aeration mode according to the oxygen demand of the sewage at different positions of the plug-flow type aeration device, such that the excessive aeration at the rear section in the traditional aeration mode is avoided, the power consumption is effectively reduced, the energy saving purpose is achieved, and the biochemical system can stably operate.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, in particular to a plug-flow aeration device coupling gradual aeration with mechanical stirring. Background Art

[0002] The aeration tank is the core of the entire sewage treatment system, and the plug-flow aeration tank is the most widely used type of aeration tank. In order to meet the water quality standards, most sewage treatment plants often over-aerate during actual operation. This not only increases power consumption, but also makes the dissolved oxygen concentration of the mixed liquid in the back section of the plug-flow aeration tank, which has a lower oxygen demand, too high, which has an adverse effect on the subsequent treatment process.

[0003] Therefore, many sewage treatment plants have reduced the aeration volume in the rear section of the plug flow aeration tank. However, reducing the aeration volume will weaken the stirring effect of aeration on the activated sludge, causing some activated sludge to settle prematurely in the rear section of the plug flow aeration tank, and the activated sludge mixed liquid cannot remain in a completely suspended state. The premature sedimentation of activated sludge can cause the removal effect of pollutants to deteriorate in the short term. In the long term, it can change the activated sludge concentration, sludge age and microbial flora in the plug flow aeration tank, and eventually lead to the collapse of the biochemical system. Summary of the invention

[0004] The present invention provides a plug-flow aeration device coupled with decreasing aeration and mechanical stirring, which solves the following problems: the conventional aeration method of the existing plug-flow aeration device for sewage treatment has the problem of excessive aeration leading to increased power consumption, too high dissolved oxygen in the rear section affecting the subsequent process, and reducing the aeration volume will weaken the stirring and cause the activated sludge to settle prematurely, thereby affecting the treatment effect and even causing the biochemical system to collapse. The aeration volume can be reduced, energy can be saved, and the activated sludge mixed liquid in the rear section of the plug-flow aeration tank with insufficient aeration stirring can be fully mixed and always kept in a suspended state, so that the biochemical system can operate stably.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: a plug-flow aeration device coupled with decreasing aeration and mechanical stirring, comprising: A plug-flow aeration device, wherein an air distribution main pipe and an aeration branch pipe are installed in the plug-flow aeration device, and the installation density of the aeration branch pipe gradually decreases along the plug-flow aeration device; A blower, connected to the air distribution main pipe, is used to supply gas to the plug-flow aeration device; A gas flow meter, installed on the gas distribution main pipe, for monitoring and regulating the gas flow; The microporous aerator is installed on the aeration branch pipe to diffuse the gas in the mixed liquid of the plug flow aeration device in the form of tiny bubbles, supply oxygen to the activated sludge and suspend the mixed liquid of the plug flow aeration device; The stirring system is installed in the middle and rear section of the aeration tank where the aeration stirring effect is insufficient, to enhance the stirring effect to keep the activated sludge mixture in suspension and to enhance the oxygen mass transfer efficiency.

[0006] Preferably, the aeration branch pipe is connected to the air distribution main pipe, an internal thread base is fixed on the aeration branch pipe, the microporous aerator is connected to the internal thread base of the aeration branch pipe via an external thread, and the microporous aerator is evenly installed on the aeration branch pipe.

[0007] Preferably, the stirring system is composed of a four-blade stirring paddle, a stirring shaft and a driving motor. The four-blade stirring paddle is connected to the stirring shaft and is installed in the middle and rear section of the plug flow aeration device with a smaller aeration volume and below the liquid surface. The driving motor is connected to the stirring shaft to rotate the stirring shaft. The stirring shaft extends below the liquid surface of the plug flow aeration device and above the microporous aerator.

[0008] Preferably, the drive motor is fixed above the liquid surface by a steel structure support platform.

[0009] Preferably, the plug-flow aeration device is provided with a water inlet at the end with a higher aeration density, and a water outlet at the end with a lower aeration density.

[0010] Preferably, it also includes dissolved oxygen sensors arranged at the front section, middle section and rear section of the plug flow aeration device for real-time monitoring of the dissolved oxygen concentration in the mixed liquid of each section.

[0011] Preferably, it also includes a flow sensor arranged at the water inlet for real-time monitoring of the sewage inflow.

[0012] Preferably, it further comprises a PLC controller, and the PLC controller is electrically connected to the dissolved oxygen sensor, the flow sensor, the gas flow meter, the electric regulating valve and the frequency converter.

[0013] Preferably, the electric regulating valve is installed on the gas distribution main pipe and is used in conjunction with the gas flow meter. The opening of the electric regulating valve is controlled by the PLC controller to accurately adjust the gas flow entering the aeration branch pipe. The frequency converter is connected to the drive motor, and the PLC controller controls the frequency converter to change the power supply frequency of the drive motor to adjust the rotation speed of the agitator shaft.

[0014] Preferably, the method for using the plug flow aeration device coupled with decreasing aeration and mechanical stirring comprises the following steps: Turn on the blower to deliver gas to the aeration branch pipe through the air distribution main pipe, and the gas diffuses into the mixed liquid in the plug flow aeration device in the form of tiny bubbles through the microporous aerator, so as to supply oxygen to the activated sludge and suspend the mixed liquid, wherein, according to the needs along the plug flow aeration device, the aeration is gradually reduced by controlling the installation density of the aeration branch pipe to gradually decrease; Monitor and adjust the gas flow rate through the gas flow meter to make the gas flow rate in the gas distribution main meet the needs of the current stage; The dissolved oxygen sensors installed in the front, middle and rear sections of the plug-flow aeration device monitor the dissolved oxygen concentration in each section of the mixed liquid in real time. According to the dissolved oxygen concentration data, the opening of the electric regulating valve is adjusted through the PLC controller to adjust the gas flow entering the aeration branch pipe; When it is detected that the aeration stirring effect is insufficient in the middle and rear sections of the aeration tank, the stirring system is started, the driving motor drives the stirring shaft to rotate, and the stirring shaft drives the four-blade stirring paddle to rotate, stirring the activated sludge mixed liquid in the middle and rear sections, so that the activated sludge mixed liquid remains in a suspended state and the oxygen mass transfer efficiency is enhanced; At the same time, the flow sensor installed at the water inlet monitors the sewage inflow in real time, and transmits the flow information to the PLC controller. The PLC controller adjusts the power supply frequency of the drive motor through the frequency converter according to the sewage inflow information and the dissolved oxygen concentration information, and then adjusts the speed of the stirring shaft to meet the stirring intensity requirements under different sewage flow rates.

[0015] The present invention provides a plug-flow aeration device that couples gradual aeration with mechanical stirring. It has the following beneficial effects: 1. The present invention reasonably distributes aeration and stirring intensity according to the pollutant concentration and treatment requirements of sewage at different locations, which not only avoids energy waste caused by excessive aeration, but also solves the problem of activated sludge sedimentation that may be caused by traditional aeration alone, and ensures the suspended state of activated sludge and the activity of microorganisms in the entire treatment process, thereby achieving efficient and stable operation of sewage treatment and ensuring that the effluent water quality meets the standards.

[0016] 2. The device of the present invention includes components such as a plug-flow aeration device, an air distribution main pipe, an aeration branch pipe, a blower, a gas flow meter, a microporous aerator and a stirring system, so as to solve the problems of excessive aeration in conventional aeration methods, which leads to increased power consumption, excessive dissolved oxygen in the rear stage affecting subsequent processes, and reducing the aeration volume will weaken the stirring and cause the activated sludge to settle prematurely, thereby affecting the treatment effect and even causing the biochemical system to collapse. The aeration volume can be reduced, energy can be saved, and the rear stage activated sludge mixed liquid in the plug-flow aeration tank with insufficient aeration and stirring can be fully mixed and always kept in a suspended state, so that the biochemical system can operate stably.

[0017] 3. The present invention uses a gradual aeration method to accurately control the aeration volume according to the oxygen demand of sewage at different positions in the plug-flow aeration device, thereby avoiding excessive aeration in the middle and later stages of the traditional aeration method, effectively reducing power consumption and achieving energy saving.

[0018] 4. The stirring system of the present invention plays a role in the middle and later stages when the aeration stirring effect is insufficient, so that the activated sludge mixture always remains in a suspended state. This not only ensures the effect of removing pollutants in the short term, but also maintains the stability of the activated sludge concentration, sludge age and microbial flora in the plug flow aeration device in the long term, thereby ensuring the stable operation of the biochemical system. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of a plug-flow aeration device coupled with decreasing aeration and mechanical stirring according to the present invention; Figure 2 It is a structural top view of a plug-flow aeration device coupled with decreasing aeration and mechanical stirring according to the present invention; Figure 3 It is a cross-sectional view of the middle and rear sections of a plug-flow aeration device coupled with decreasing aeration and mechanical stirring according to the present invention; Figure 4 The present invention is a bottom view of a four-blade stirring paddle of a plug-flow aeration device that couples decreasing aeration with mechanical stirring.

[0020] Among them, 1. plug flow aeration device; 2. water inlet; 3. water outlet; 4. blower; 5. air distribution main pipe; 6. microporous aerator; 7. gas flow meter; 8. aeration branch pipe; 9. four-blade stirring paddle; 10. stirring shaft; 11. drive motor; 12. support platform. DETAILED DESCRIPTION

[0021] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Please see attached Figure 1 -Attached Figure 4 The embodiment of the present invention provides a plug flow aeration device coupled with decreasing aeration and mechanical stirring, comprising: a plug flow aeration device 1, wherein an air distribution main pipe 5 and an aeration branch pipe 8 are installed in the plug flow aeration device 1, and the installation density of the aeration branch pipe 8 gradually decreases along the plug flow aeration device 1; a blower 4, connected to the air distribution main pipe 5, used for gas supply to the plug flow aeration device 1; a gas flow meter 7, installed on the air distribution main pipe 5, used for monitoring and adjusting the gas flow; a microporous aerator 6, installed on the aeration branch pipe 8, so that the gas diffuses in the mixed liquid of the plug flow aeration device 1 in the form of tiny bubbles, oxygenates the activated sludge, and suspends the mixed liquid of the plug flow aeration device 1; a stirring system, installed in the middle and rear section of the aeration tank 1 where the aeration stirring effect is insufficient, enhances the stirring effect to keep the activated sludge mixed liquid in a suspended state, and enhances the oxygen mass transfer efficiency.

[0023] During operation, first, sewage flows into the water inlet of the plug-flow aeration device 1. At the same time, the blower 4 is started to transport air and other gases through the air distribution main pipe 5. The air distribution main pipe 5 distributes the gas to the aeration branch pipes 8 connected thereto. The installation density of the aeration branch pipes 8 gradually decreases along the process of the plug-flow aeration device 1. This arrangement of decreasing aeration makes it possible for more aeration branch pipes 8 to provide sufficient aeration for the sewage when it flows through the front section of the plug-flow aeration device 1, because the concentration of pollutants in the sewage is high and the amount of oxygen required for microbial metabolism is large. As the sewage flows to the outlet, the pollutants are gradually decomposed, the demand for oxygen is reduced, and the number of aeration branch pipes 8 is reduced accordingly, achieving decreasing aeration.

[0024] The gas flow meter 7 installed on the gas distribution main pipe 5 will monitor the gas flow in real time and feed back the information to the corresponding control system (such as a PLC controller). The output of the blower 4 or the opening of the relevant valve can be adjusted to ensure that the gas flow entering the aeration branch pipe 8 meets the requirements of the current sewage treatment stage.

[0025] The microporous aerator 6 is installed on the aeration branch pipe 8, and diffuses the gas from the aeration branch pipe 8 into the mixed liquid of the plug flow aeration device 1 in the form of tiny bubbles. These tiny bubbles not only provide the activated sludge with the required oxygen, but also the disturbance energy generated during the rising process can suspend the mixed liquid to a certain extent. In the front section of the plug flow aeration device 1, the aeration effect of the microporous aerator 6 is sufficient to suspend the mixed liquid, but in the middle and rear sections, due to the gradual decrease in aeration intensity, insufficient stirring may result.

[0026] At this time, the stirring system begins to work. The stirring system consists of a four-blade stirring paddle 9, a stirring shaft 10 and a driving motor 11. The driving motor 11 drives the stirring shaft 10 to rotate, and then drives the four-blade stirring paddle 9 to perform stirring operations in the middle and rear sections of the aeration tank 1. The stirring system is installed in the middle and rear sections where the aeration stirring effect is insufficient. Through the rotation of the four-blade stirring paddle 9, the activated sludge mixture continues to remain suspended in this area to avoid the precipitation of activated sludge. At the same time, the water flow movement generated by the stirring system can also enhance the oxygen mass transfer efficiency, making the oxygen transfer in the sewage more sufficient, so that microorganisms can better use oxygen to decompose pollutants.

[0027] Through such coordinated operation, each component jointly realizes the aeration and stirring treatment of sewage in the plug-flow aeration device 1. The entire device reasonably distributes the aeration and stirring intensity according to the pollutant concentration and treatment requirements of the sewage at different positions, which not only avoids the energy waste caused by excessive aeration, but also solves the problem of activated sludge sedimentation that may be caused by traditional aeration alone, and ensures the suspended state of activated sludge and the activity of microorganisms in the entire treatment process, thereby achieving efficient and stable operation of sewage treatment and ensuring that the effluent water quality meets the standards. In this way, the conventional aeration method solves the problems of excessive aeration leading to increased power consumption, excessive dissolved oxygen in the rear stage affecting subsequent processes, and reducing the aeration volume will weaken the stirring and cause the activated sludge to settle prematurely, thereby affecting the treatment effect and even causing the biochemical system to collapse. The aeration volume can be reduced, energy can be saved, and the activated sludge mixed liquid in the rear stage of the plug-flow aeration tank with insufficient aeration and stirring can be fully mixed, and always kept in a suspended state, so that the biochemical system can operate stably.

[0028] In one embodiment, the aeration branch pipe 8 is connected to the air distribution main pipe 5, an internal thread base is fixed on the aeration branch pipe 8, the microporous aerator 6 is connected to the internal thread base of the aeration branch pipe 8 through an external thread, and the microporous aerator 6 is evenly installed on the aeration branch pipe 8. Compared with other connection methods (such as simple socket or snap connection), the threaded connection can withstand certain pressure and vibration, and can effectively prevent gas leakage at the connection. During the operation of the aeration system, the sealing of the gas transmission channel from the air distribution main pipe 5 through the aeration branch pipe 8 to the microporous aerator 6 is ensured, gas loss caused by loose connection or leakage is avoided, and the stability and efficiency of the aeration process are ensured, while also reducing the potential safety hazards and environmental pollution problems caused by gas leakage.

[0029] In one embodiment, the stirring system is composed of a four-blade stirring paddle 9, a stirring shaft 10 and a driving motor 11. The four-blade stirring paddle 9 is connected to the stirring shaft 10 and is installed in the middle and rear section of the plug-flow aeration device 1 with a small aeration volume and below the liquid surface. The driving motor 11 is connected to the stirring shaft 10 to rotate the stirring shaft 10, and the stirring shaft 10 extends below the liquid surface of the plug-flow aeration device 1 and the upper part of the microporous aerator 6. The driving motor 11 starts to work, it is connected to the stirring shaft 10, and drives the stirring shaft 10 to rotate by converting electrical energy into mechanical energy. The rotation of the stirring shaft 10 drives the four-blade stirring paddle 9 connected thereto to rotate. The four-blade stirring paddle 9 is installed in the middle and rear section of the plug-flow aeration device 1 with a small aeration volume and is located below the liquid surface. At the same time, the stirring shaft 10 extends below the liquid surface of the plug-flow aeration device 1 and the upper part of the microporous aerator 6. Through the effective stirring of the stirring system in the middle and rear sections of the aeration device, coordinated with the front-end aeration process of the taper aeration, a complete sewage treatment process of coordinated aeration and stirring is formed, which ensures the good state of the activated sludge mixture in the entire plug flow aeration device 1 and avoids the activated sludge sedimentation problem that may be caused by relying solely on aeration.

[0030] In one embodiment, the drive motor 11 is fixed above the liquid surface by a steel structure support platform 12. The steel structure has high strength and stability, and can withstand the weight of the drive motor 11 and the vibration and torque generated during operation. Fixing the drive motor 11 above the liquid surface by the steel structure support platform 12 can ensure that the drive motor 11 is in a stable installation position and will not be displaced or shaken due to the reaction force generated by the stirring shaft 10 and the four-blade stirring paddle 9 during operation.

[0031] In one embodiment, the plug-flow aeration device 1 is provided with a water inlet 2 at the end with high aeration density, and a water outlet 3 at the end with low aeration density. As the sewage flows from the water inlet 2 to the water outlet 3 in the plug-flow aeration device 1, the pollutants are gradually decomposed by microorganisms, and the demand for oxygen is gradually reduced, so the aeration density gradually decreases along the way. This arrangement conforms to the natural process of pollutant degradation in sewage, and the change of pollutant concentration from high to low in sewage matches the gradient of aeration intensity from strong to weak.

[0032] In one embodiment, it also includes dissolved oxygen sensors arranged at the front section, middle section and rear section of the plug flow aeration device 1, which are used to monitor the dissolved oxygen concentration in the mixed liquid of each section in real time. It also includes a flow sensor arranged at the water inlet 2, which is used to monitor the sewage inflow in real time. It also includes a PLC controller, which is electrically connected to the dissolved oxygen sensor, the flow sensor, the gas flow meter 7, the electric regulating valve and the frequency converter.

[0033] The electric regulating valve is installed on the gas distribution main pipe 5 and is used in conjunction with the gas flow meter 7. The opening of the electric regulating valve is controlled by the PLC controller to accurately adjust the gas flow entering the aeration branch pipe 8. The frequency converter is connected to the drive motor 11, and the PLC controller controls the frequency converter to change the power supply frequency of the drive motor 11 to adjust the rotation speed of the stirring shaft 10.

[0034] When the plug-flow aeration device 1 starts to operate, the flow sensor arranged at the water inlet 2 monitors the inflow of sewage in real time. The flow sensor sends the detected sewage flow data to the PLC controller.

[0035] At the same time, the dissolved oxygen sensors distributed in the front section, middle section and rear section of the plug flow aeration device 1 will monitor the dissolved oxygen concentration in the mixed liquid at the corresponding position in real time, and transmit these dissolved oxygen data to the PLC controller.

[0036] The gas flow meter 7 is installed on the gas distribution main pipe 5, which continuously measures the gas flow and feeds back the measurement results to the PLC controller.

[0037] The PLC controller controls the opening of the electric regulating valve according to the received dissolved oxygen concentration information, combined with the inflow of sewage, according to the pre-set algorithm and control logic. When the dissolved oxygen concentration of a section is lower than the set value, the PLC controller will send a signal to the electric regulating valve to increase its opening, thereby increasing the gas flow in the gas distribution main pipe 5, and then allowing more gas to enter the mixed liquid through the aeration branch pipe 8 and the microporous aerator 6, thereby increasing the dissolved oxygen concentration of the section; conversely, when the dissolved oxygen concentration is higher than the set value, the PLC controller will reduce the opening of the electric regulating valve and reduce the gas flow to achieve gradual aeration.

[0038] The gas flow meter 7 feeds back the real-time monitored gas flow data to the PLC controller to form a closed-loop control, ensuring that the actual gas flow is consistent with the control signal of the PLC controller, thereby ensuring the accuracy of the aeration process.

[0039] The PLC controller will also adjust the power supply frequency of the drive motor 11 by controlling the frequency converter according to the sewage inflow and dissolved oxygen concentration data.

[0040] In one embodiment, when the inlet flow rate increases or the dissolved oxygen concentration is low, the PLC controller will increase the output frequency of the inverter, thereby increasing the rotation speed of the drive motor 11, thereby increasing the stirring speed of the stirring shaft 10 and the four-blade stirring paddle 9, enhancing the stirring intensity, enhancing the oxygen mass transfer efficiency, and promoting the mixing of the activated sludge mixture and the transfer of oxygen; conversely, when the inlet flow rate decreases or the dissolved oxygen concentration meets the requirements, the PLC controller will reduce the output frequency of the inverter to save energy.

[0041] By setting dissolved oxygen sensors and flow sensors at different key locations, key parameters in the sewage treatment process, such as dissolved oxygen concentration and sewage flow, can be accurately grasped. According to these precise real-time data, the PLC controller accurately adjusts the opening of the electric regulating valve and the speed of the drive motor 11 to achieve refined control of aeration and stirring. By accurately controlling the aeration and stirring intensity, excessive aeration and excessive stirring are avoided, and the optimal allocation of aeration and stirring resources is achieved. On the premise of meeting the treatment requirements, the aeration and stirring intensity is increased only when necessary, avoiding unnecessary energy consumption. The energy consumption in the sewage treatment process is reduced, the operating cost is reduced, and the service life of the equipment is increased, and the energy-saving and efficient operation of the sewage treatment system is achieved.

[0042] In one embodiment, the method for using the plug flow aeration device coupled with decreasing aeration and mechanical stirring comprises the following steps: The blower 4 is turned on to deliver gas to the aeration branch pipe 8 through the air distribution main pipe 5. The gas diffuses into the mixed liquid in the plug flow aeration device 1 in the form of tiny bubbles through the microporous aerator 6, thereby supplying oxygen to the activated sludge and suspending the mixed liquid. According to the needs along the plug flow aeration device 1, the aeration is gradually reduced by controlling the installation density of the aeration branch pipe 8 to gradually decrease; The gas flow rate is monitored and adjusted by the gas flow meter 7 so that the gas flow rate in the gas distribution main pipe 5 meets the requirements of the current stage; The dissolved oxygen concentration in each mixed liquid section is monitored in real time by using dissolved oxygen sensors installed in the front section, middle section and rear section of the plug flow aeration device 1. According to the dissolved oxygen concentration data, the opening of the electric regulating valve is adjusted through the PLC controller to adjust the gas flow entering the aeration branch pipe 8; When it is detected that the aeration stirring effect is insufficient in the middle and rear sections of the aeration tank 1, the stirring system is started, the driving motor 11 drives the stirring shaft 10 to rotate, and the stirring shaft 10 drives the four-blade stirring paddle 9 to rotate, so as to stir the activated sludge mixed liquid in the middle and rear sections, so that the activated sludge mixed liquid remains in a suspended state and the oxygen mass transfer efficiency is enhanced; At the same time, the flow sensor installed at the water inlet 2 monitors the sewage inflow in real time, and transmits the flow information to the PLC controller. The PLC controller adjusts the power supply frequency of the drive motor 11 through the frequency converter according to the sewage inflow information and the dissolved oxygen concentration information, and then adjusts the rotation speed of the stirring shaft 10 to meet the stirring intensity requirements under different sewage flow rates.

[0043] Specifically, first install the plug flow aeration device 1, and fix the air distribution main pipe 5 at the middle position of the bottom thereof. The air distribution main pipe 5 needs to be horizontal and stable so as to be connected to the aeration branch pipe 8 later.

[0044] Connect the blower 4 to the air distribution main pipe 5, and ensure that the connection is tight to prevent gas leakage. The blower 4 provides gas power for the entire aeration system and transports air to the air distribution main pipe 5.

[0045] A gas flow meter 7 is installed on the gas distribution main pipe 5, and the gas flow meter 7 is used to monitor the gas flow passing through the gas distribution main pipe 5 in real time, so as to adjust the aeration amount according to actual needs.

[0046] According to the gradually decreasing density from the water inlet to the water outlet, several aeration branches 8 are connected to the air distribution main pipe 5. On the aeration branch pipes 8, microporous aerators 6 are evenly installed by means of the cooperation of the internal thread base and the external thread. The function of the microporous aerator 6 is to diffuse the gas in the mixed liquid of the plug flow aeration device 1 in the form of tiny bubbles, provide oxygen for the activated sludge, and keep the mixed liquid in a suspended state.

[0047] The stirring system is installed in the middle and rear sections of the plug-flow aeration device 1 where the aeration density is relatively low. Specifically, the drive motor 11 is first fixed to the upper end of the plug-flow aeration device 1 through a support platform 12 of a stainless steel structure. The drive motor 11 is connected to the stirring shaft 10, which needs to extend vertically downward into the water body, and the end extends above the microporous aerator 6. On the stirring shaft 10, two four-blade stirring paddles 9 are connected through an inner and outer spiral structure, one is located at the bottom end of the stirring shaft 10, and the other is fixed at a lower middle position of the stirring shaft 10.

[0048] An inlet 2 is provided at the end of the plug-flow aeration device 1 with a high aeration density, and an outlet 3 is provided at the end with a low aeration density, to ensure that sewage can flow in from the inlet 2 according to the designed flow direction, and flow out from the outlet 3 after aeration and stirring treatment.

[0049] When working, start the blower 4, distribute the air to each aeration branch pipe 8 through the air distribution main pipe 5, and then diffuse into the mixed liquid of the plug flow aeration device 1 in the form of tiny bubbles through the microporous aerator 6. Since the installation density of the aeration branch pipe 8 gradually decreases along the way, decreasing aeration is achieved. In the front stage of aeration, the concentration of pollutants in the sewage is high and the oxygen demand is large, and sufficient oxygen is provided by relatively more microporous aerators 6; as the sewage flows to the outlet 3, the pollutants are gradually decomposed, the oxygen demand decreases, and the aeration volume is also reduced accordingly. Such a design not only meets the oxygen demand requirements of sewage at different stages, but also avoids excessive aeration in the latter stage.

[0050] The driving motor 11 drives the stirring shaft 10 to rotate, and then drives the four-blade stirring paddle 9 to rotate. In the middle and rear sections of the aeration device, due to the reduction in aeration volume, the stirring effect of aeration on the activated sludge is weakened, and the stirring system comes into play at this time. The rotation of the four-blade stirring paddle 9 keeps the activated sludge mixed liquid in this area in a suspended state at all times, preventing the activated sludge from settling prematurely. At the same time, stirring enhances the fluidity of the water body, improves the oxygen mass transfer efficiency, and enables oxygen to be more fully utilized by the activated sludge.

[0051] The present invention has the following advantages: Energy-saving effect: Through the gradual aeration method, the aeration volume is accurately controlled according to the oxygen demand of the sewage at different positions in the plug flow aeration device 1, avoiding excessive aeration in the middle and later stages of the traditional aeration method, effectively reducing power consumption and achieving the purpose of energy saving.

[0052] Stable operation effect: The stirring system plays a role in the middle and later stages when the aeration stirring effect is insufficient, so that the activated sludge mixed liquid always remains in a suspended state. This not only ensures the effect of removing pollutants in the short term, but also maintains the stability of the activated sludge concentration, sludge age and microbial flora in the plug flow aeration device 1 in the long term, ensuring the stable operation of the biochemical system.

[0053] In the prior art, many sewage treatment plants have the problem of energy waste caused by excessive aeration. At the same time, when trying to reduce the aeration volume in the rear section of the aeration tank to save energy, the activated sludge mixed liquid in the rear section of the aeration tank is not stirred enough, and part of the activated sludge settles, which eventually leads to the collapse of the biochemical system. The plug-flow aeration device of the present invention, which couples the decreasing aeration with mechanical stirring, solves the problem of energy waste caused by excessive aeration through a unique decreasing aeration design and a reasonable layout of the stirring system, and avoids the problems of activated sludge settling and biochemical system instability caused by reducing the aeration volume, providing an efficient, energy-saving and stable solution for sewage treatment.

[0054] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A plug flow aeration device with coupling of decreasing aeration and mechanical stirring, characterized in that: include: A plug-flow aeration device (1), wherein an air distribution main pipe (5) and an aeration branch pipe (8) are installed in the plug-flow aeration device (1), and the installation density of the aeration branch pipe (8) gradually decreases along the plug-flow aeration device (1); A blower (4) is connected to the air distribution main pipe (5) and is used to supply gas to the plug-flow aeration device (1); A gas flow meter (7), installed on the gas distribution main pipe (5), for monitoring and regulating the gas flow; A microporous aerator (6) is installed on the aeration branch pipe (8) to diffuse gas in the mixed liquid of the plug flow aeration device (1) in the form of micro bubbles, thereby supplying oxygen to the activated sludge and suspending the mixed liquid of the plug flow aeration device (1); The stirring system is installed in the middle and rear section of the aeration tank (1) where the aeration stirring effect is insufficient, so as to enhance the stirring effect to keep the activated sludge mixed liquid in a suspended state and enhance the oxygen mass transfer efficiency.

2. A plug flow aeration device with coupled decreasing aeration and mechanical stirring according to claim 1, characterized in that: The aeration branch pipe (8) is connected to the air distribution main pipe (5), an internal thread base is fixed on the aeration branch pipe (8), the microporous aerator (6) is connected to the internal thread base of the aeration branch pipe (8) via an external thread, and the microporous aerator (6) is evenly installed on the aeration branch pipe (8).

3. The plug flow aeration device with coupled decreasing aeration and mechanical stirring according to claim 1, characterized in that: The stirring system is composed of a four-blade stirring paddle (9), a stirring shaft (10) and a driving motor (11). The four-blade stirring paddle (9) is connected to the stirring shaft (10) and is installed in the middle and rear section of the plug-flow aeration device (1) with a smaller aeration volume and below the liquid surface. The driving motor (11) is connected to the stirring shaft (10) to rotate the stirring shaft (10). The stirring shaft (10) extends below the liquid surface of the plug-flow aeration device (1) and above the microporous aerator (6).

4. The plug flow aeration device with coupled decreasing aeration and mechanical stirring according to claim 3, characterized in that: The driving motor (11) is fixed above the liquid surface by a steel structure support platform (12).

5. The plug flow aeration device with coupled decreasing aeration and mechanical stirring according to claim 1, characterized in that: The plug-flow aeration device (1) is provided with a water inlet (2) at the end with a high aeration density, and a water outlet (3) at the end with a low aeration density.

6. The plug flow aeration device with coupled decreasing aeration and mechanical stirring according to claim 1, characterized in that: It also includes dissolved oxygen sensors arranged at the front section, middle section and rear section of the plug flow aeration device (1) for real-time monitoring of the dissolved oxygen concentration in the mixed liquid of each section.

7. A plug-flow aeration device with coupled decreasing aeration and mechanical stirring according to claim 6, characterized in that: It also includes a flow sensor arranged at the water inlet (2) for real-time monitoring of the amount of sewage inflow.

8. The plug-flow aeration device with coupled decreasing aeration and mechanical stirring according to claim 6, characterized in that: It also includes a PLC controller, which is electrically connected to the dissolved oxygen sensor, the flow sensor, the gas flow meter (7), the electric regulating valve and the frequency converter.

9. The plug-flow aeration device with coupled decreasing aeration and mechanical stirring according to claim 8, characterized in that: The electric regulating valve is installed on the gas distribution main pipe (5) and is used in conjunction with the gas flow meter (7). The PLC controller controls the opening of the electric regulating valve to accurately adjust the gas flow entering the aeration branch pipe (8). The frequency converter is connected to the drive motor (11). The PLC controller controls the frequency converter to change the power supply frequency of the drive motor (11) to adjust the rotation speed of the stirring shaft (10).

10. A plug flow aeration device with coupled decreasing aeration and mechanical stirring according to any one of claims 1 to 9, characterized in that: The method for using the plug-flow aeration device coupled with decreasing aeration and mechanical stirring comprises the following steps: The blower (4) is turned on to deliver gas to the aeration branch pipe (8) through the air distribution main pipe (5); the gas diffuses into the mixed liquid in the plug flow aeration device (1) in the form of tiny bubbles through the microporous aerator (6), thereby supplying oxygen to the activated sludge and suspending the mixed liquid; wherein, according to the demand along the plug flow aeration device (1), the aeration is gradually reduced by controlling the installation density of the aeration branch pipe (8) to gradually decrease; The gas flow rate is monitored and adjusted by a gas flow meter (7) so that the gas flow rate in the gas distribution main pipe (5) meets the requirements of the current stage; Using dissolved oxygen sensors installed at the front section, middle section and rear section of the plug flow aeration device (1) to monitor the dissolved oxygen concentration in each section of the mixed liquid in real time, and adjusting the opening of the electric regulating valve through the PLC controller according to the dissolved oxygen concentration data to adjust the gas flow entering the aeration branch pipe (8); When it is detected that the aeration stirring effect is insufficient in the middle and rear sections of the aeration tank (1), the stirring system is started, the driving motor (11) drives the stirring shaft (10) to rotate, and the stirring shaft (10) drives the four-blade stirring paddle (9) to rotate, so as to stir the activated sludge mixed liquid in the middle and rear sections, so that the activated sludge mixed liquid remains in a suspended state and the oxygen mass transfer efficiency is enhanced; At the same time, a flow sensor arranged at the water inlet (2) monitors the sewage inflow in real time, and transmits the flow information to the PLC controller. The PLC controller adjusts the power supply frequency of the drive motor (11) through the frequency converter according to the sewage inflow information and the dissolved oxygen concentration information, and further adjusts the rotation speed of the stirring shaft (10) to meet the stirring intensity requirements under different sewage flow rates.

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