AOA and AAO dual-mode biochemical treatment system

Abstract

The present application relates to a kind of AOA and AAO dual-mode biochemical treatment system, applied to sewage treatment technical field, comprising: by setting two groups of symmetrically arranged biochemical pool body, AAO mode sewage treatment is carried out to the sewage entering or AOA mode sewage treatment is carried out to the sewage entering, while designing double sludge reflux channel to realize sludge reflux in anaerobic zone and sludge reflux in anoxic zone, the multiple point reflux of sludge makes the reflux system of AAO and AOA two processes more flexible and convenient control, strengthens the denitrification effect of AOA process, beneficial to AOA sludge reflux ratio deployment while taking into account AAO sludge reflux design, solve the sludge reflux problem under AAO mode and AOA mode.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a dual-mode biochemical treatment system of AOA and AAO. Background Technology

[0002] In the field of wastewater treatment technology, biological treatment is the core treatment unit, mainly based on activated sludge and biofilm processes. Among activated sludge processes, the most common is the AAO process (anaerobic-anoxic-aerobic process). The AAO process is simple to operate, easy to maintain, mature, and effective. However, it also has certain problems. For raw water with low carbon content, the denitrification efficiency is low. This is because the aerobic stage requires sufficient aeration to ensure nitrification and ammonia nitrogen removal. To ensure total nitrogen removal, a large amount of nitrified liquid from the aerobic end needs to be returned to the anoxic stage. Therefore, the anoxic stage introduces a large amount of dissolved oxygen, causing the carbon source in the raw water to be largely consumed. If the carbon source in the raw water is low, denitrification in the anoxic stage will be hindered, resulting in low denitrification efficiency. Therefore, when the C / N ratio in the raw water is less than 3, meaning the carbon source is insufficient, the AAO process often requires additional carbon source supplementation to ensure that the total nitrogen effluent meets the standards. Thus, the AAO process is not suitable for situations where the influent has relatively low carbon and nitrogen content.

[0003] In recent years, the AOA (Anaerobes-Aerobic-Anoxic) process has been extensively studied and validated through engineering-level experiments, achieving good results. AOA refers to an anaerobic-aerobic-anoxic process. In the anaerobic stage, organic matter in the raw water is utilized by microorganisms and converted into an internal carbon source, PHA, for storage. In the aerobic stage, endogenous nitrification and denitrification simultaneously remove total nitrogen. In the anoxic stage, intracellular glycogen or PHA is used for denitrification. Simultaneously, the AOA process can reduce the consumption of internal carbon sources in the aerobic tank. When addressing insufficient C / N ratio in the influent, the anoxic tank utilizes the PHA synthesized during the anaerobic stage. The AOA process ensures high nitrogen removal efficiency through endogenous denitrification and high biological phosphorus removal rate through denitrification, thus saving on external carbon source consumption and chemical phosphorus removal dosage. The AOA process requires less oxygen in the aerobic stage than the AAO process, saving on aeration volume. However, the AOA technology adjusts the ratio of aerobic to anoxic zones, increasing the volume of the anoxic zone and decreasing the volume of the aerobic zone. If the influent carbon source and aeration volume in the aerobic zone are normal, it can make it difficult to control dissolved oxygen in the downstream anoxic zone, affecting nitrogen removal efficiency. When the removal requirements for ammonia nitrogen are higher than those for total nitrogen, the AOA process is more difficult to control.

[0004] Therefore, both AAO and AOA processes have their advantages when dealing with varying influent C / N ratios. Furthermore, in actual operation, the influent carbon source often varies seasonally due to dry seasons, rainy seasons, or heating seasons, and some industrial enterprises experience cyclical changes due to production cycles. Therefore, using a single AAO or AOA process to treat actual wastewater may not consistently deliver its advantages. A more flexible tank design and operating mode need to be designed, considering both the influent carbon source and total nitrogen removal characteristics, while taking into account the advantages and disadvantages of each process.

[0005] Patent application number 202210237362.7 discloses a wastewater biochemical system and operation method based on MBBR with dual modes of AOA and AAO. The reaction tank includes an anaerobic zone, a main aerobic zone, a selective zone, a main anoxic zone, a post-anoxic zone, and a post-aerobic zone. Ammonia nitrogen removal is enhanced by adding packing material in the main aerobic zone through a sludge-film composite method. Its AAO mode is essentially a two-stage AO process. The tank is divided into 6 compartments. However, only the wastewater system is disclosed, and no sludge return and nitrification liquid return systems are set up, which indicates a system defect.

[0006] Patent application number 202210238598.2 discloses a micro-powered MBBR enhanced AOA and AAO dual-mode system and operation method. It divides the biochemical system into a first reaction tank, a second reaction tank, and a third reaction tank. The anoxic section of the first and third reaction tanks is divided into many partitions, gates, and water passages. MBBR packing is added to the aerobic zone of the first reaction tank to enhance ammonia nitrogen removal. However, the tank has too many partitions, each with different functions. In actual application, this will increase the difficulty of system control and automatic control system setup. It will also increase the investment in tanks, equipment, and subsequent equipment maintenance points to a certain extent. Furthermore, the sludge return system does not provide a detailed description of the sludge return process and pipelines.

[0007] Patent application number 202210238610.X discloses an aerobic adjustable, land-saving AOA and AAO dual-mode wastewater biochemical system and its operation method. It includes six parts: anaerobic zone, main aerobic zone, selective zone, post-anoxic zone, main anoxic zone, and post-aerobic zone. The main aerobic zone is equipped with suspended packing material and coupled with an enhanced system with MBBR. In addition, the selective zone is divided into three small compartments. The entire tank is divided into eight spaces. It can operate in both AOA and AAO modes by switching through gates. However, the equipment selection and installation are relatively complicated, and the sludge return system is not mentioned. Summary of the Invention

[0008] In view of this, the purpose of the present invention is to provide a dual-mode biochemical treatment system of AOA and AAO to solve the problems in the prior art, which has a complicated tank design and does not explain how the sludge is returned when taking into account both AOA and AAO dual-mode processes.

[0009] According to a first aspect of the present invention, a dual-mode biochemical treatment system of AOA and AAO is provided, the system comprising:

[0010] Two sets of symmetrically arranged biological treatment tanks and a sludge return pumping station;

[0011] The two sets of symmetrically arranged biochemical tanks are used to treat the incoming sewage in either AAO mode or AOA mode.

[0012] A first sludge return channel is provided between the adjacent walls of the two symmetrically arranged biological treatment tanks. The sludge return pumping station is used to pump sludge into the first sludge return channel. The first sludge return channel is provided with a first sludge return channel outlet gate. There are two first sludge return channel outlet gates, which are symmetrically arranged on both sides of the first sludge return channel. The two first sludge return channel outlet gates are used to connect the first sludge return channel with the anaerobic zone of the two symmetrically arranged biological treatment tanks. The proportion of sludge returned into the anaerobic zone of the two symmetrically arranged biological treatment tanks is controlled by the first sludge return channel outlet gates.

[0013] The outer layers of the adjacent walls of the two symmetrically arranged biochemical tanks are respectively provided with second sludge return channels. The sludge return pump room is also used to pump sludge into the two second sludge return channels respectively. The second sludge return channels are provided with second sludge return channel outlet gates. The second sludge return channel outlet gates are used to connect the second sludge return channels with the anoxic zones of their respective biochemical tanks.

[0014] When the two symmetrically arranged biological treatment tanks are used in AOA mode for wastewater treatment, when the carbon source of the wastewater influent meets the preset first influent carbon source range, the effluent gate of the first sludge return channel is opened and the effluent gate of the second sludge return channel is closed to carry out sludge return in the anaerobic zone; when the carbon source of the wastewater influent meets the preset second influent carbon source range, both the effluent gates of the first sludge return channel and the effluent gates of the second sludge return channel are opened, and sludge return in both the anaerobic and anoxic zones is carried out simultaneously.

[0015] When the two symmetrically arranged biochemical tanks are used for wastewater treatment in AAO mode, the effluent gate of the first sludge return channel is opened and the effluent gate of the second sludge return channel is closed to allow sludge return from the anaerobic zone.

[0016] Preferably,

[0017] The sludge return pump station includes:

[0018] The system includes a first booster pump, a second booster pump, a first sludge return pipe, a second sludge return pipe, and a function switching valve.

[0019] The first booster pump is used to pump sludge into the first sludge return pipe, which is connected to the first sludge return channel.

[0020] The second booster pump is used to pump sludge into the second sludge return pipe, which is connected to two second sludge return channels respectively.

[0021] The first sludge return pipe and the second sludge return pipe are connected by a connecting pipe, and a function switching valve is provided in the connecting pipe. The function switching valve is normally closed.

[0022] When the first booster pump fails, the function switching valve is opened, and the sludge is pumped into the first sludge return pipe by the second booster pump.

[0023] When the second booster pump fails, the function switching valve is opened, and the sludge is pumped into the second sludge return pipe by the first booster pump.

[0024] Preferably,

[0025] Both sets of symmetrically arranged biochemical pools include:

[0026] Anaerobic zone, hypoxic zone, aerobic zone, first variable zone, and second variable zone;

[0027] The anaerobic zone is connected to the aerobic zone through a first gate, and the anaerobic zone is connected to the anoxic zone through a second gate;

[0028] The hypoxic zone is connected to the aerobic zone through a third gate, the hypoxic zone is connected to the first variable zone through a fourth gate, and the hypoxic zone is connected to the second variable zone through a fifth gate.

[0029] The first variable zone and the second variable zone are connected through a sixth gate;

[0030] The second variable zone is provided with a water outlet channel, which is connected to a water outlet pipe for discharging the treated wastewater.

[0031] The anaerobic zone is equipped with an anaerobic zone stirrer; the anoxic zone is equipped with an anoxic zone propeller; the aerobic zone is equipped with an aerobic zone propeller, which includes a submersible jet generator and an aerator; the first variable zone is equipped with a first variable zone stirrer and an aerator to provide both aerobic and anoxic operating modes; the second variable zone is equipped with an aerator and an internal reflux pump to provide both aerobic and anoxic operating modes.

[0032] Preferably, it further includes:

[0033] Wastewater inlet device;

[0034] The wastewater inlet device includes: a main inlet pipe, an inlet channel, an inlet distribution channel, a first inlet gate, and a second inlet gate;

[0035] The main water inlet pipe is connected to the water inlet channel, the water inlet channel is connected to the water inlet distribution channel, and the water inlet distribution channel is connected to the first water inlet gate and the second water inlet gate respectively;

[0036] The first inlet gate is used for sewage to enter the anaerobic zone, and the second inlet gate is used for sewage to enter the anoxic zone;

[0037] When the two sets of symmetrically arranged biological tanks are used for sewage treatment in AOA mode, the second inlet gate is closed, and the sewage is sent into the anaerobic zone through the first inlet gate.

[0038] When the two symmetrically arranged biochemical tanks are used for sewage treatment in AAO mode, and the carbon source of the sewage influent meets the preset third influent carbon source range, the first influent gate and the second influent gate are opened simultaneously to adopt multi-point water intake; otherwise, water is introduced through the first influent gate.

[0039] Preferably,

[0040] The outer wall of the second variable zone is also provided with a nitrification liquid return channel, which is used to connect the second variable zone and the anoxic zone;

[0041] When the two symmetrically arranged biological tanks are used for wastewater treatment in AAO mode, the nitrified liquid in the second variable zone is lifted to the nitrified liquid return channel by the nitrified liquid return pump, and the nitrified liquid is returned to the anoxic zone.

[0042] Preferably,

[0043] The hydraulic retention time of the first variable zone is 20% to 40% of that of the aerobic zone; the hydraulic retention time of the second variable zone is 10% to 15% of that of the aerobic zone.

[0044] When the aerator of the first variable zone is turned on and the agitator of the first variable zone is turned off, the first variable zone operates in aerobic mode to prolong the aerobic reaction time.

[0045] When the aerator in the first variable zone is turned off and the agitator in the first variable zone is turned on, the first variable zone operates in anoxic mode to prolong the anoxic reaction time.

[0046] Preferably,

[0047] When the two symmetrically arranged biological treatment tanks are used for wastewater treatment in AOA mode, the first, fourth, and fifth gates are open; the second, third, and sixth gates are closed.

[0048] Wastewater passes through the main inlet pipe, inlet channel, and inlet distribution channel in sequence. It then enters the anaerobic zone through the first inlet gate for anaerobic reaction, then enters the aerobic zone through the first gate for aerobic reaction, then enters the first variable zone for aerobic or anoxic reaction, then enters the anoxic zone through the fourth gate for anoxic reaction, and continues to enter the second variable zone through the fifth gate for aerobic or anoxic reaction. Finally, it is discharged through the outlet channel and outlet pipe in sequence.

[0049] Preferably,

[0050] When the two symmetrically arranged biological treatment tanks are used for sewage treatment in AAO mode, the first, fourth, and fifth gates are closed; the second, third, and sixth gates are open.

[0051] Wastewater passes through the main inlet pipe, inlet channel, and inlet distribution channel in sequence. It then enters the anaerobic zone through the first inlet gate for anaerobic reaction, then enters the anoxic zone through the second gate for anoxic reaction, then enters the aerobic zone through the third gate for aerobic reaction, then enters the first variable zone for aerobic or anoxic reaction, then enters the second variable zone through the sixth gate for aerobic or anoxic reaction, and finally is discharged through the outlet channel and outlet pipe in sequence.

[0052] The technical solutions provided by the embodiments of the present invention may include the following beneficial effects:

[0053] This application sets up two symmetrically arranged biological treatment tanks to treat incoming wastewater using either the AAO mode or the AOA mode. Simultaneously, it designs dual sludge return channels to achieve sludge return from both the anaerobic and anoxic zones. This multi-point sludge return makes the return systems for both AAO and AOA processes more flexible and convenient to control, enhances the denitrification effect of the AOA process, and facilitates the adjustment of the AOA sludge return ratio while also considering the AAO sludge return design, thus solving the sludge return problem in both AAO and AOA modes.

[0054] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the invention. Attached Figure Description

[0055] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0056] Figure 1 This is a schematic diagram illustrating the principle of sludge and wastewater transfer in the AOA mode according to an exemplary embodiment.

[0057] Figure 2 This is a schematic diagram illustrating the sludge and wastewater transfer principle in the AAO mode according to another exemplary embodiment;

[0058] Figure 3 This is a schematic diagram of material balance in each zone under the AOA mode, according to another exemplary embodiment;

[0059] Figure 4 This is a schematic diagram of material balance in each zone under the AAO mode, according to another exemplary embodiment;

[0060] In the attached diagram: A0—Anaerobic zone, A1—Anoxic zone, O—Aerobic zone, T1—First variable zone, T2—Second variable zone, L1—Inlet channel, L2—Inlet distribution channel, L3—Second sludge return channel, L4—First sludge return channel, L5—Nitrified liquid return channel, L6—Outlet channel, C1—First inlet gate, C2—Second inlet gate, C3—Outlet gate of the first sludge return channel, C4—Outlet gate of the second sludge return channel, X1—First gate, X2—Second gate, X3—Third gate, X4—Fourth gate, X5—Fifth gate, X6—Sixth gate, Q1—Main inlet pipe, Q2—Outlet pipe, Q3—First sludge return pipe, Q4—Second sludge return pipe, M1—Function switching valve, M2—First lift pump, M3—Second lift pump. Detailed Implementation

[0061] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the invention as detailed in the appended claims.

[0062] Example 1:

[0063] As attached Figure 1 and appendix Figure 2 As shown:

[0064] The system described in this application includes two sets of biological treatment tanks and a sludge return pumping station, wherein the two sets of biological treatment tanks are arranged symmetrically.

[0065] Each group of biological tanks is divided into five areas by partition walls: anaerobic zone A0, anoxic zone A1, aerobic zone O, first variable zone T1, and second variable zone T2. The anaerobic zone A0 is the same width as the anoxic zone A1, and the aerobic zone O is the same width as the first variable zone T1 and the second variable zone T2. The innovative tank design in this application achieves the effect of switching between AOA and AAO functions with the minimum number of tank compartments.

[0066] A first sludge return channel L4 is provided between the adjacent walls of two symmetrically arranged biological treatment tanks. A sludge return pumping station is used to pump sludge into the first sludge return channel L4. The first sludge return channel L4 is equipped with a first sludge return channel outlet gate C3. There are two first sludge return channel outlet gates C3, which are symmetrically arranged on both sides of the first sludge return channel L4. The two first sludge return channel outlet gates C3 are used to connect the first sludge return channel L4 with the anaerobic zone A0 of the two symmetrically arranged biological treatment tanks. The proportion of returned sludge entering the anaerobic zone of the two symmetrically arranged biological treatment tanks is controlled by the first sludge return channel outlet gates C3.

[0067] The outer layers of the adjacent walls of the two symmetrically arranged biological tanks are respectively provided with second sludge return channels L3. The sludge return pump room is also used to pump sludge into the two second sludge return channels L3 respectively. The second sludge return channel L3 is provided with a second sludge return channel outlet gate C4. The second sludge return channel outlet gate C4 is used to connect the second sludge return channel L3 with the anoxic zone A1 of each biological tank.

[0068] The sludge return pump station includes a first lift pump M2, a second lift pump M3, a first sludge return pipe Q3, a second sludge return pipe Q4, and a function switching valve M1. The first lift pump M2 pumps sludge into the first sludge return pipe Q3, which is connected to a first sludge return channel L4. The second lift pump M3 pumps sludge into the second sludge return pipe Q4, which is connected to two second sludge return channels L3. The first sludge return pipe Q3 and the second sludge return pipe Q4 are connected by a connecting pipe, in which a function switching valve M1 is installed. The sludge return pump station adopts a design concept of mutual backup for the return pumps, achieving an ideal sludge return ratio under actual influent loads of 25% to 100%. The first lift pump M2 and the second lift pump M3 can serve as backups for each other, with the following principle:

[0069] When the first lift pump M2 is damaged, the function switching valve M1 is opened. At this time, the sludge can be pumped into the first sludge return pipe Q3 through the second lift pump M3. The second lift pump M3 is a backup of the first lift pump M2 and is used to realize the sludge return of the anaerobic zone A0.

[0070] When the second lift pump M3 fails, the function switching valve M1 is opened, and the sludge is pumped into the second sludge return pipe Q4 through the first lift pump M2. At this time, the first lift pump M2 can be used as a backup for the second lift pump M3 to realize the sludge return of the anoxic zone A1.

[0071] It is worth emphasizing that the sludge return in this application adopts the design concept of zoned return and multi-point return. The first sludge return channel L4 and the second sludge return channel L3 are used to return sludge to the anaerobic zone A0 and the anoxic zone A1, respectively, to achieve two-point sludge return. In order to ensure the uniformity of sludge distribution, the sludge returned to the two anaerobic tanks A0 enters the first sludge return channel L4 through the first sludge return pipe Q3. The amount of sludge returned on both sides is controlled by the sludge outlet gate C3 of the first sludge return channel. The sludge returned to the anoxic zone A1 first enters the sludge return inlet channel (to the anoxic zone) sludge distribution well through the second sludge return pipe Q4. After being distributed by the weir, it flows into the second sludge return channel L3 and finally flows into the anoxic zone A1 from the sludge outlet gate C4. This allows the sludge return channels to be flexibly switched in both AOA and AAO modes, and the tank functions to be adjusted.

[0072] Meanwhile, under AOA and AAO modes, the activation conditions for the first sludge return channel L4 and the second sludge return channel L3 are as follows:

[0073] In AOA operation mode: when the ΔBOD (biological oxygen demand) / ΔTN in the influent wastewater is greater than 4, sludge return to the anaerobic zone A0 can be activated only, that is, sludge return is carried out only through the first sludge return channel L4. When the ΔBOD / ΔTN in the influent wastewater is less than 4, that is, when the carbon source in the influent is insufficient, sludge return to the anoxic zone A1 is activated, that is, sludge return is carried out simultaneously through the first sludge return channel L4 and the second sludge return channel L3, thereby increasing the sludge concentration in the anoxic zone A1, thereby enhancing the denitrification effect and saving carbon source.

[0074] In AAO operation mode: the sludge is returned to the anaerobic zone A0 through the first sludge return pipe Q3. The sludge return ratio of the two anaerobic zones A0 is adjusted by controlling the opening of the effluent gate C3 of the first sludge return channel, and the sludge return ratio is controlled at 100%. If necessary (such as to increase the sludge concentration to resist shock load or to inhibit sludge aging under low load conditions), the sludge return ratio of the anaerobic zone A0 can be increased to a maximum of 200% by opening the function switching valve M1 while opening the second lift pump, but closing the effluent gate C4 of the second sludge return channel.

[0075] Example 2:

[0076] Such as appendage 1 and appendage Figure 2 As shown:

[0077] Anaerobic zone A0 is connected to aerobic zone O through the first gate X1, and anaerobic zone A0 is connected to anoxic zone A1 through the second gate X2.

[0078] The hypoxic zone A1 is connected to the aerobic zone O through the third gate X3, the hypoxic zone A1 is connected to the first variable zone T1 through the fourth gate X4, and the hypoxic zone A1 is connected to the second variable zone T2 through the fifth gate X5.

[0079] The first variable zone T1 and the second variable zone T2 are connected through the sixth gate X6;

[0080] The second variable zone T2 is equipped with an outlet channel L6, which is connected to the outlet pipe Q2 to discharge the treated wastewater. The outer wall of the second variable zone T2 is also equipped with a nitrification liquid return channel L5, which is used to connect the second variable zone T2 and the anoxic zone A1.

[0081] An anaerobic zone A0 is equipped with an anaerobic zone stirrer; an anoxic zone A1 is equipped with an anoxic zone propeller; an aerobic zone O is equipped with an aerobic zone propeller, which includes a submersible jet generator and an aerator; the first variable zone T1 is equipped with a first variable zone stirrer and an aerator to provide both aerobic and anoxic operating modes; the second variable zone T2 is equipped with an aerator and an internal reflux pump to provide both aerobic and anoxic operating modes.

[0082] The wastewater treatment process under AOA operation mode is as follows:

[0083] Gate X1, Gate X4, and Gate X5 are open; Gate X2, Gate X3, and Gate X6 are closed.

[0084] Wastewater passes through the main inlet pipe Q1, inlet channel L1, and inlet distribution channel L2 in sequence. It then enters the anaerobic zone A0 through the first inlet gate C1 for anaerobic reaction. Next, it enters the aerobic zone O through the first gate X1 for aerobic reaction. Then, it enters the first variable zone T1 for aerobic or anoxic reaction. It then enters the anoxic zone A1 through the fourth gate X4 for anoxic reaction. Finally, it enters the second variable zone T2 through the fifth gate X5 for aerobic or anoxic reaction. Finally, it is discharged through the outlet channel L6 and outlet pipe Q2 in sequence.

[0085] In AOA operation mode, the sludge is returned to the anaerobic zone A0 through the first sludge return pipe Q3. The opening of the effluent gate C3 of the first sludge return channel is controlled to adjust the sludge return ratio of the two anaerobic zones. The sludge return ratio is 50-100%. The sludge concentration C in the anaerobic zone A0 and the aerobic zone O is controlled at 4000-5000 mg / L.

[0086] The sludge is returned to the channel through the second sludge return pipe Q4. Water is evenly distributed through the channel weir and the sludge is returned to the anoxic zone A1. The sludge return ratio is 50-100%. The sludge concentration 4C / 3 in the anoxic zone A1 is controlled at 5300mg / L-6700mg / L to enhance the denitrification process.

[0087] When the influent C / N ratio is relatively reasonable, only the sludge return to the anaerobic zone A0 can be turned on. When the influent C / N ratio is low and the carbon source is insufficient, the sludge return to the anoxic zone A1 can be turned on to increase the sludge concentration in the anoxic zone, enhance the denitrification effect, and save carbon source.

[0088] When the system focuses on controlling ammonia nitrogen, the first variable zone T1 and the second variable zone T2 should be aerated and the mixing should be turned off; when the system focuses on controlling total nitrogen (TN), the first variable channel T1 and the second variable zone T2 should be aerated and the mixing should be turned on.

[0089] In the aerobic zone, the dissolved oxygen (DO) concentration (DO) should be controlled at 1.5-3 mg / L.

[0090] The wastewater treatment process in AAO operation mode is as follows:

[0091] Gate X1, Gate X4, and Gate X5 are closed; Gate X2, Gate X3, and Gate X6 are open.

[0092] Wastewater passes through the main inlet pipe Q1, inlet channel L1, and inlet distribution channel L2 in sequence. It then enters the anaerobic zone A0 through the first inlet gate C1 for anaerobic reaction. Next, it enters the anoxic zone A1 through the second gate X2 for anoxic reaction. It then enters the aerobic zone O through the third gate X3 for aerobic reaction. After that, it enters the first variable zone T1 for aerobic or anoxic reaction. Finally, it enters the second variable zone T2 through the sixth gate X6 for aerobic or anoxic reaction. Finally, it is discharged through the outlet channel L6 and outlet pipe Q2 in sequence.

[0093] In AAO operation mode, if the △BOD / △TN of the influent sewage is less than 4, the second influent gate C2 will be opened and the multi-point influent operation mode will be entered.

[0094] In AAO operation mode, the nitrified liquor in the second variable zone T2 is lifted to the nitrified liquor return channel L5 by the nitrified liquor lift pump and returned to the anoxic zone A1, wherein the nitrified liquor return ratio is 200-400%.

[0095] The sludge is returned to the anaerobic zone A0 through the first sludge return pipe Q3. The sludge return ratio of the two anaerobic zones is adjusted by controlling the opening of the effluent gate C3 of the first sludge return channel. The sludge return ratio is controlled at 100%. If necessary, the return ratio can be increased to a maximum of 200% by turning on the sludge return pump of the anoxic zone A1, opening the M1 valve, and closing the C4 gate.

[0096] The second sludge return pipe Q4 is not turned on, and the entire system ensures single-point sludge return. The sludge concentration C in the anaerobic zone A0, the anoxic zone A1, and the aerobic zone O is controlled at 4000-5000 mg / L.

[0097] When the system is focused on controlling ammonia nitrogen, aeration is activated in the first variable zone T1 and the second variable zone T2, while stirring is deactivated. When the system is focused on controlling total nitrogen (TN), aeration is deactivated in the first variable zone T1 and the second variable zone T2, while stirring is activated.

[0098] In the aerobic zone, the dissolved oxygen (DO) concentration is controlled at 2-4 mg / L.

[0099] In this application, all the above-mentioned channels are arranged on the outer layer of a single pool body, including inlet channel L1, inlet distribution channel L2, second sludge return channel L3, first sludge return channel L4, and nitrification liquid return channel L5. This ensures that the scum on the pool surface can be smoothly pushed to the end when operating in any mode, and the scum will not be stuck due to the bottom of the channel being lower than the water surface.

[0100] As attached Figure 1 and appendix Figure 2 As shown, the inlet channel L1 and the return sludge channel (L3, L4) are concentrated on the central wall of the entire tank, which helps to ensure that there are no channels blocking other partitions in the tank, and that the scum on the surface of the tank can pass smoothly through the scum hole at the top of the partition wall, thus avoiding affecting the operation and appearance.

[0101] As attached Figure 1 and appendix Figure 2 As shown, the intersection of the inlet channel L1 and the sludge return channel (L3, L4) is an upper and lower cross structure, with the inlet channel L1 located below and the sludge return channel (L3, L4) located above, thus achieving the functions of sewage inlet and sludge return within a single plane without affecting each other.

[0102] As attached Figure 1 and appendix Figure 2 As shown, the overlapping part of the effluent channel L6 and the nitrification liquid return channel L5 is a cross structure. L6 is a cantilevered channel. After the effluent enters from one side of the L6 channel, it flows into the vertically penetrating effluent well along the L6 channel, and then flows out from the effluent pipe Q2. A nitrification liquid return pump is installed directly below the L6 channel. After being pumped, the nitrified liquid enters the space outside the L6 channel (this space leads directly to the top of the pool), and then flows into the cantilevered nitrification liquid return channel L5. The nitrified liquid returns to the anoxic zone A1. The cross layout of the effluent channel L6 and the nitrification liquid return channel L5 solves the problem of the arrangement of the effluent and nitrification liquid return space and avoids short-circuiting.

[0103] The HRT (hydraulic retention time) of the first variable zone T1 is approximately 20% to 40% of that of the aerobic zone O. When aeration is turned on and stirring is turned off, the first variable zone T1 operates in an aerobic state, which can prolong the aerobic reaction time. When aeration is turned off and stirring is turned on, it operates in an anoxic state, which prolongs the anoxic reaction time.

[0104] The HRT of the second variable zone T2 is approximately 10% to 15% of that of the aerobic zone O;

[0105] Under AAO conditions, the function can be adjusted according to nitrification or denitrification requirements. When nitrification is the primary requirement, T2 is used to turn on aeration and turn off stirring. When denitrification is the primary requirement, aeration is turned off and stirring is turned on, which can serve as a degassing zone to reduce the dissolved oxygen concentration in the nitrification liquid and facilitate the denitrification reaction after reflux. Under AOA conditions, aeration is turned off and stirring is turned on, operating in an anoxic mode.

[0106] Example 3:

[0107] As attached Figure 3 As shown, assuming the system influent flow rate is Q, the maintenance concentration in the anaerobic zone A0 is C, the sludge return flow rate in the secondary sedimentation tank is 2Q, and the sludge return concentration is 2C, then the return sludge entering the anaerobic zone A0 and the anoxic zone A1 are Q and 2C respectively; the total flow rate entering the aerobic zone O is 2C, the maintenance concentration in the aerobic zone O is C, the total flow rate entering the anoxic zone A1 is 3Q, and the maintenance concentration is 4C / 3. The sludge concentration in the anoxic zone A1 is higher than that in other tanks, therefore the denitrification effect is stronger.

[0108] As attached Figure 4 As shown, assuming the system influent flow rate is Q, the anaerobic zone A0 tank maintains a concentration of C, the secondary sedimentation tank sludge return flow rate is Q, the sludge return concentration is 2C, the nitrification liquor return flow rate is 2Q, and the concentration is C; then the flow rates of the subsequent anoxic zone A1 tank, aerobic zone O tank, first variable zone T1 tank, and second variable zone T2 tank are all 4Q, and the sludge concentration is C.

[0109] In summary, this application can achieve dual-mode operation of the same system, addressing system inapplicability and operational performance issues caused by seasonal changes in water volume and quality. It can achieve stable and efficient denitrification, while simultaneously resolving issues related to water distribution, sludge uniformity, and surface scum blockage in the pool design.

[0110] It is understood that the same or similar parts in the above embodiments can be referred to each other, and the contents not described in detail in some embodiments can be referred to the same or similar contents in other embodiments.

[0111] It should be noted that in the description of this invention, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means at least two.

[0112] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of the invention includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as will be understood by those skilled in the art to which embodiments of the invention pertain.

[0113] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0114] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0115] Furthermore, the functional units in the various embodiments of the present invention can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0116] The storage media mentioned above can be read-only memory, disk, or optical disk, etc.

[0117] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0118] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A dual-mode biochemical treatment system of AOA and AAO, characterized in that, The system includes: Two sets of symmetrically arranged biological treatment tanks and a sludge return pumping station; Both sets of symmetrically arranged biochemical pools include: Anaerobic zone, hypoxic zone, aerobic zone, first variable zone, and second variable zone; The anaerobic zone is connected to the aerobic zone through a first gate, and the anaerobic zone is connected to the anoxic zone through a second gate; The hypoxic zone is connected to the aerobic zone through a third gate, the hypoxic zone is connected to the first variable zone through a fourth gate, and the hypoxic zone is connected to the second variable zone through a fifth gate. The first variable zone and the second variable zone are connected through a sixth gate; The second variable zone is provided with a water outlet channel, which is connected to a water outlet pipe for discharging the treated wastewater. The anaerobic zone is equipped with an anaerobic zone stirrer; the anoxic zone is equipped with an anoxic zone propeller; the aerobic zone is equipped with an aerobic zone propeller, which includes a submersible jet generator and an aerator; the first variable zone is equipped with a first variable zone stirrer and an aerator to provide both aerobic and anoxic operating modes; the second variable zone is equipped with an aerator and an internal reflux pump to provide both aerobic and anoxic operating modes. The two sets of symmetrically arranged biochemical tanks are used to treat the incoming sewage in either AAO mode or AOA mode. A first sludge return channel is provided between the adjacent walls of the two symmetrically arranged biochemical pools. The sludge return pumping station is used to pump sludge into the first sludge return channel. The first sludge return channel is equipped with a first sludge return channel outlet gate. There are two first sludge return channel outlet gates, which are symmetrically arranged on both sides of the first sludge return channel. The two first sludge return channel outlet gates are used to connect the first sludge return channel with the anaerobic zone of the two symmetrically arranged biological treatment tanks. The proportion of sludge returned into the anaerobic zone of the two symmetrically arranged biological treatment tanks is controlled by the first sludge return channel outlet gates. The outer layers of the adjacent walls of the two symmetrically arranged biochemical tanks are respectively provided with second sludge return channels. The sludge return pump room is also used to pump sludge into the two second sludge return channels respectively. The second sludge return channels are provided with second sludge return channel outlet gates. The second sludge return channel outlet gates are used to connect the second sludge return channels with the anoxic zones of their respective biochemical tanks. Also includes: Wastewater inlet device; The wastewater inlet device includes: a main inlet pipe, an inlet channel, an inlet distribution channel, a first inlet gate, and a second inlet gate; The main water inlet pipe is connected to the water inlet channel, the water inlet channel is connected to the water inlet distribution channel, and the water inlet distribution channel is connected to the first water inlet gate and the second water inlet gate respectively; The first inlet gate is used for sewage to enter the anaerobic zone, and the second inlet gate is used for sewage to enter the anoxic zone; When the two sets of symmetrically arranged biological tanks are used for sewage treatment in AOA mode, the second inlet gate is closed, and the sewage is sent into the anaerobic zone through the first inlet gate. When the two sets of symmetrically arranged biochemical tanks are used for sewage treatment in AAO mode, and the carbon source of the sewage influent meets the preset third influent carbon source range, the first influent gate and the second influent gate are opened simultaneously to adopt multi-point water intake; otherwise, water is introduced through the first influent gate. The outer wall of the second variable zone is also provided with a nitrification liquid return channel, which is used to connect the second variable zone and the anoxic zone; When the two sets of symmetrically arranged biological tanks are used for sewage treatment in AAO mode, the nitrified liquid in the second variable zone is lifted to the nitrified liquid return channel by the nitrified liquid return pump, and the nitrified liquid is returned to the anoxic zone. When the two symmetrically arranged biological treatment tanks are used in AOA mode for wastewater treatment, when the carbon source of the wastewater influent meets the preset first influent carbon source range, the effluent gate of the first sludge return channel is opened and the effluent gate of the second sludge return channel is closed to carry out sludge return in the anaerobic zone; when the carbon source of the wastewater influent meets the preset second influent carbon source range, both the effluent gates of the first sludge return channel and the effluent gates of the second sludge return channel are opened, and sludge return in both the anaerobic zone and the anoxic zone is carried out simultaneously. When the two symmetrically arranged biological treatment tanks are used in the AAO mode for sewage treatment, the effluent gate of the first sludge return channel is opened and the effluent gate of the second sludge return channel is closed to carry out sludge return in the anaerobic zone. When the two symmetrically arranged biological treatment tanks are used for wastewater treatment in AOA mode, the first, fourth, and fifth gates are open; the second, third, and sixth gates are closed. Wastewater passes through the main inlet pipe, inlet channel, and inlet distribution channel in sequence. It then enters the anaerobic zone through the first inlet gate for anaerobic reaction, then enters the aerobic zone through the first gate for aerobic reaction, then enters the first variable zone for aerobic or anoxic reaction, then enters the anoxic zone through the fourth gate for anoxic reaction, and continues to enter the second variable zone through the fifth gate for aerobic or anoxic reaction. Finally, it is discharged through the outlet channel and outlet pipe in sequence. When the two symmetrically arranged biological treatment tanks are used for sewage treatment in AAO mode, the first, fourth, and fifth gates are closed; the second, third, and sixth gates are open. Wastewater passes through the main inlet pipe, inlet channel, and inlet distribution channel in sequence. It then enters the anaerobic zone through the first inlet gate for anaerobic reaction, then enters the anoxic zone through the second gate for anoxic reaction, then enters the aerobic zone through the third gate for aerobic reaction, then enters the first variable zone for aerobic or anoxic reaction, then enters the second variable zone through the sixth gate for aerobic or anoxic reaction, and finally is discharged through the outlet channel and outlet pipe in sequence.

2. The system according to claim 1, characterized in that, The sludge return pump station includes: The system includes a first booster pump, a second booster pump, a first sludge return pipe, a second sludge return pipe, and a function switching valve. The first booster pump is used to pump sludge into the first sludge return pipe, which is connected to the first sludge return channel. The second booster pump is used to pump sludge into the second sludge return pipe, which is connected to two second sludge return channels respectively. The first sludge return pipe and the second sludge return pipe are connected by a connecting pipe, and a function switching valve is provided in the connecting pipe. The function switching valve is normally closed. When the first booster pump fails, the function switching valve is opened, and the sludge is pumped into the first sludge return pipe by the second booster pump. When the second booster pump fails, the function switching valve is opened, and the sludge is pumped into the second sludge return pipe by the first booster pump.

3. The system according to claim 2, characterized in that, The hydraulic retention time of the first variable zone is 20% to 40% of that of the aerobic zone; the hydraulic retention time of the second variable zone is 10% to 15% of that of the aerobic zone. When the aerator of the first variable zone is turned on and the agitator of the first variable zone is turned off, the first variable zone operates in aerobic mode to prolong the aerobic reaction time. When the aerator in the first variable zone is turned off and the agitator in the first variable zone is turned on, the first variable zone operates in anoxic mode to prolong the anoxic reaction time.

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