A bioreactor based on denitrification for phosphorus removal and a simultaneous nitrogen and phosphorus removal process for wastewater.

Abstract

This invention discloses a bioreactor based on denitrification for phosphorus removal and a simultaneous nitrogen and phosphorus removal process for wastewater, belonging to the field of wastewater treatment technology. It includes an anaerobic tank, two sequencing batch reactors (SBRs), two equalization tanks, an aerobic tank, and an anoxic tank. The anaerobic tank receives wastewater to be treated and activated sludge returned from the equalization tanks, and performs an anaerobic phosphorus release process under the action of activated sludge. The SBRs receive the treated liquid from the anaerobic tanks and the returned liquid from the aerobic tanks, and perform anoxic denitrification under influent conditions, stirring conditions, and pre-sedimentation conditions. The two SBRs are connected in parallel for multi-cycle alternating reactions. The two equalization tanks are connected in series with different SBRs. The aerobic tank receives the effluent from the SBRs and / or the equalization tanks, and performs aerobic carbonization and / or nitrification reactions. The anoxic tank receives the treated liquid from the aerobic tank and performs a denitrification for phosphorus removal. The simultaneous nitrogen and phosphorus removal process for wastewater using a bioreactor based on denitrification for phosphorus removal can achieve complete nitrification of ammonia nitrogen in wastewater, with high total nitrogen removal efficiency.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a bioreactor based on denitrification and phosphorus removal, and a process for simultaneous nitrogen and phosphorus removal from wastewater. Background Technology

[0002] The AAO (Anaerobic-Anoxic-Oxic) process is a commonly used secondary wastewater treatment process in municipal wastewater treatment plants. However, it suffers from sludge age conflicts and carbon source competition, and is costly for treating wastewater with low C / N ratios. Denitrification phosphorus removal technology cultivates polyphosphate-accumulating bacteria (DPAOs) in an anaerobic / anoxic environment. DPAOs perform different physiological activities in the anaerobic and anoxic stages, absorbing phosphates from wastewater while simultaneously reducing nitrates, thus achieving simultaneous nitrogen and phosphorus removal and reducing carbon source demand (dual carbon utilization). It is suitable for wastewater with low C / N ratios and shows great promise.

[0003] Denitrification phosphorus removal processes are mainly divided into two categories: single-sludge processes and dual-sludge processes. In single-sludge systems, taking the BCFS process as an example, DPAOs and nitrifying bacteria coexist in the same system. However, it is difficult to balance the optimal growth conditions for both in the system parameter settings, and it is also impossible to resolve the contradictions between carbon sources and sludge age among different bacterial communities. In contrast, a more optimized solution is the dual-sludge process. The dual-sludge system effectively separates DPAOs and nitrifying bacteria by placing them in independent reaction units. Typical examples of this type of process include the Dephanox process and the A2N-SBR process. Laboratory studies have shown that the Dephanox process and the A2N-SBR process can achieve good phosphorus and nitrogen removal effects. However, there are still some shortcomings in putting these processes into actual production operation, mainly manifested in problems such as high ammonia nitrogen concentration in the effluent, low total nitrogen removal rate, and process stability being easily affected by water quality. In the Dephanox process, ammonia nitrogen exceeding the sludge load is not nitrified; in the A2N-SBR process, the volume exchange of the A2SBR tank is generally only 50% to 70%, and the ammonia nitrogen in the remaining tank volume is not nitrified; the dual sludge denitrification phosphorus removal system disclosed in Chinese patent document CN10600725A also has the problem of some wastewater not being nitrified during the reactor reversal flow process, which leads to a high concentration of ammonia nitrogen in the corresponding process effluent, thus affecting the total nitrogen removal effect.

[0004] Furthermore, the operational stability of the denitrification phosphorus removal process mainly depends on whether the nitrogen and phosphorus concentration ratio in the influent is appropriate. However, in practice, the influent water quality fluctuates. When the nitrate concentration is too low, phosphorus uptake is limited due to insufficient electron acceptors; if nitrate is excessive, it will affect phosphorus release from the circulating sludge or the anaerobic stage of the next process, and excess nitrate itself also means a low total nitrogen removal rate.

[0005] To address the aforementioned issues, this invention proposes a bioreactor based on denitrification and phosphorus removal, along with a simultaneous nitrogen and phosphorus removal process for wastewater. This fully leverages the advantages of denitrification and phosphorus removal and is suitable for practical production applications. Summary of the Invention

[0006] To fully leverage the advantages of the dual-sludge denitrification phosphorus removal process and address the shortcomings of the existing technologies, this invention provides a bioreactor based on denitrification phosphorus removal, which can achieve full nitrification of ammonia nitrogen in wastewater and improve total nitrogen removal efficiency.

[0007] The specific technical solution adopted is as follows:

[0008] A bioreactor based on denitrification for phosphorus removal includes an anaerobic tank, two sequencing batch reactors, two conditioning tanks, an aerobic tank, and an anoxic tank.

[0009] The anaerobic tank is used to receive wastewater to be treated and to receive activated sludge returned from the equalization tank. The anaerobic phosphorus release process under the action of activated sludge takes place in the anaerobic tank. The anaerobic tank treatment liquid is fed into different sequencing batch tanks.

[0010] The sequencing batch reactor (SBR) receives the treated effluent from the anaerobic tank and the return effluent from the aerobic tank, and conducts anoxic denitrification under influent, stirred, and pre-sedimentation conditions. Two SBRs are connected in parallel for multiple alternating cycles. In the first half of a reaction cycle, one SBR receives the treated effluent from the anaerobic tank and the return effluent from the aerobic tank, and conducts anoxic denitrification under influent conditions. Simultaneously, the supernatant from the previous cycle is discharged into the aerobic tank, and the remaining treated effluent enters the corresponding equalization tank. Meanwhile, the connecting parts between the other SBR and the anaerobic and aerobic tanks are closed, and anoxic denitrification under stirred and pre-sedimentation conditions occurs sequentially within this SBR. The reaction process involves the following steps: In the latter half of a reaction cycle, the operation and function of the two sequencing batch reactors are switched (the connection between the sequencing batch reactor that underwent anoxic denitrification under influent conditions in the first half of the cycle and the anaerobic and aerobic reactors is closed; anoxic denitrification under stirring and pre-sedimentation conditions is carried out sequentially within this sequencing batch reactor; simultaneously, the connection between the other sequencing batch reactor and the anaerobic and aerobic reactors is opened, receiving the treated liquid from the anaerobic reactor and the return liquid from the aerobic reactor, and carrying out anoxic denitrification under influent conditions; at the same time, the supernatant from the previous cycle is discharged into the aerobic reactor, and the remaining treated liquid enters the corresponding conditioning tank); after the end of one reaction cycle, the cycle begins again.

[0011] Two equalization tanks are connected in series with different sequencing batch tanks. The equalization tanks and sequencing batch tanks are always connected. The activated sludge in the equalization tank is returned to the anaerobic tank, and the supernatant is discharged into the aerobic tank.

[0012] The aerobic tank is used to receive the effluent from the sequencing batch tank and / or conditioning tank, and aerobic carbonization and / or nitrification reactions are carried out in the aerobic tank.

[0013] The anoxic tank is used to receive the treated liquid from the aerobic tank, where further denitrification and nitrogen removal processes take place.

[0014] Specifically, in bioreactors based on denitrification for phosphorus removal, the wastewater or treated liquid in the anaerobic tank, sequencing batch reactor, and equalization tank contains activated sludge. The activated sludge circulates and transfers between the anaerobic tank, sequencing batch reactor, and equalization tank along with the wastewater or treated liquid. After the activated sludge undergoes an adsorption and phosphorus release reaction under anaerobic conditions, it mixes with the return liquid from the aerobic tank in the sequencing batch reactor. The return liquid contains nitrate nitrogen, so anoxic denitrification for phosphorus removal can be carried out in the sequencing batch reactor under anoxic conditions.

[0015] Preferably, the bioreactor based on denitrification for phosphorus removal is an integrated box structure, with treatment tanks connected by connecting valves, connecting pipes or water distribution systems, and adjacent treatment tanks sharing wall panels.

[0016] The anaerobic tank outlet side uses a thin-walled weir-type water distribution device (structure reference: Chinese patent document CN118791128A) to input the anaerobic tank treatment liquid into different sequencing batch tanks, and there is a liquid level difference between the anaerobic tank and the sequencing batch tank.

[0017] Furthermore, when the sequencing batch reactor is undergoing anoxic denitrification under stirring or pre-sedimentation conditions, the connecting parts between the sequencing batch reactor and the anaerobic and aerobic reactors are all closed, and the connecting parts between the corresponding conditioning tank and the anaerobic and aerobic reactors are also closed.

[0018] Furthermore, stirring devices are installed in the anaerobic tank and the sequencing batch reactor; stirring devices and aeration devices are installed in the conditioning tank. The installation of stirring devices and aeration devices enables reactions to take place in the conditioning tank under aeration conditions, stirring conditions, or static conditions.

[0019] Preferably, the bottom of the sequencing batch reactor (SBR) is rectangular, with a length-to-width ratio further preferably 2–4:1. The SBR is connected to the bottom of the equalization tank, which is located on the outlet side of the SBR. The overall planar shape of the SBR and the equalization tank is rectangular, with a length-to-width ratio further preferably 3–5:1. The advantages of this configuration are: the treated liquid in the SBR maintains its reaction as it travels from the inlet to the outlet, and the horizontal sedimentation effect causes the activated sludge to settle, resulting in supernatant at the outlet, ensuring that the supernatant entering the aerobic tank contains a relatively small amount of activated sludge. To improve the sedimentation effect, inclined plate shallow sedimentation facilities can also be added to the tank.

[0020] Furthermore, the aerobic tank is equipped with biological packing material on which a microbial film is cultivated, and the microorganisms carry out aerobic carbonization and / or nitrification reactions in the aerobic tank.

[0021] Furthermore, the anoxic tank is equipped with biological packing material on which a microbial film is cultivated, and the microorganisms carry out anoxic denitrification reaction in the anoxic tank.

[0022] Furthermore, sludge removal devices are installed in the equalization tank, aerobic tank, and anoxic tank to remove excess sludge and detached biofilm from the system.

[0023] The present invention also provides a process for simultaneous nitrogen and phosphorus removal from wastewater, wherein the wastewater to be treated is fed into the bioreactor based on denitrification for simultaneous nitrogen and phosphorus removal.

[0024] Specifically, the bioreactor based on denitrification and phosphorus removal has undergone sludge acclimation and preliminary commissioning before being put into use, and can be used to directly carry out multi-cycle alternating reaction processes. The process includes:

[0025] (1) The wastewater to be treated is fed into the anaerobic tank and mixed with the activated sludge returned from the adjustment tank to carry out anaerobic phosphorus release reaction under anaerobic conditions.

[0026] (2) The anaerobic treatment liquid obtained in step (1) is mixed with the aerobic return liquid and fed into different sequencing batch reactors for multiple alternating reactions. In the first half of a reaction cycle, the connecting parts between one sequencing batch reactor and the anaerobic and aerobic reactors are opened, and the sequencing batch reactor and the conditioning tank are always connected. After receiving the anaerobic treatment liquid and the aerobic return liquid, the anoxic denitrification reaction is carried out under influent conditions, and the original supernatant in the sequencing batch reactor is discharged into the aerobic reactor. The remaining liquid enters the conditioning tank corresponding to the sequencing batch reactor. At the same time, the connecting parts between another sequencing batch reactor and the anaerobic and aerobic reactors are closed, and the connecting parts between the conditioning tank corresponding to the sequencing batch reactor and the anaerobic reactor are closed. The sequencing batch reactor and the conditioning tank are always connected. The original anaerobic treatment liquid and aerobic return liquid in the reactor undergo anoxic denitrification reactions under stirring and pre-sedimentation conditions in sequence. In the second half of a reaction cycle, the operation and function of the two sequencing batch reactors are interchanged. After the end of a reaction cycle, the cycle enters the next reaction cycle.

[0027] (3) When the anoxic denitrification reaction under influent conditions is carried out in the sequencing batch tank corresponding to the equalization tank, the aeration device and the stirring device in the equalization tank are both closed. The equalization tank further treats the received liquid, so that the activated sludge is returned to the anaerobic tank and the supernatant is discharged into the aerobic tank. When the anoxic denitrification reaction under stirring conditions and pre-sedimentation conditions is carried out in the sequencing batch tank corresponding to the equalization tank, the aeration device is turned on / off and / or the stirring device is turned on / off and / or a carbon source is added to the equalization tank according to the composition of the received liquid.

[0028] (4) The supernatant discharged into the aerobic tank in step (2) or step (3) undergoes aerobic carbonization and / or nitrification under the action of aerobic biofilm;

[0029] (5) Discharge the treated liquid from the aerobic tank in step (4) into the anoxic tank to further carry out the denitrification process;

[0030] (6) Discharge the treated liquid from the anoxic tank in step (5) into the high-efficiency sedimentation tank to further remove total phosphorus and suspended solids, thus completing the simultaneous nitrogen and phosphorus removal process for wastewater.

[0031] Furthermore, in the process of simultaneous nitrogen and phosphorus removal in wastewater, the dissolved oxygen in the anaerobic tank is controlled to be <0.2 mg / L, the oxidation-reduction potential (ORP) is controlled to be <-200 mV, the dissolved oxygen in the sequencing batch reactor is controlled to be <0.5 mg / L, the dissolved oxygen in the aerobic tank is controlled to be 2-4 mg / L, and the dissolved oxygen in the anoxic tank is controlled to be <0.5 mg / L.

[0032] Preferably, the equalization tank is stirred, aerated, or has a carbon source added for reaction according to the composition of the received liquid. When the total phosphorus content in the influent of the equalization tank is >0.5 mg / L and the nitrate nitrogen content is <3 mg / L, the aeration device of the equalization tank is turned on and the dissolved oxygen is controlled. The dissolved oxygen provided by the aeration process is used as an electron acceptor to enhance the removal of total phosphorus. When the nitrate nitrogen content in the influent of the equalization tank is >5 mg / L, the agitation device of the equalization tank is turned on and a carbon source is added to the equalization tank to enhance the removal of total nitrogen. Under other conditions, the aeration device and agitation device of the equalization tank are turned off to further precipitate activated sludge and increase the activated sludge content in the return liquid.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] (1) Compared with the Dephanox and A2N processes, the wastewater simultaneous nitrogen and phosphorus removal process using the bioreactor based on denitrification and phosphorus removal provided by the present invention can achieve full nitrification of ammonia nitrogen in wastewater and improve the total nitrogen removal efficiency.

[0035] (2) The bioreactor and wastewater simultaneous denitrification and phosphorus removal process of the present invention removes nitrogen and phosphorus from wastewater through the denitrification and phosphorus removal mechanism. Compared with the traditional denitrification and phosphorus removal process, it can save carbon source replenishment, save aeration volume of about 30%, and reduce the amount of residual sludge by about 50%. It is suitable for the treatment of urban sewage and industrial wastewater that need to be denitrified and phosphorus removed.

[0036] (3) The wastewater simultaneous denitrification and phosphorus removal process of the present invention combines the activated sludge method and the biofilm method. The activated sludge and biofilm do not interfere with each other. Denitrifying bacteria and nitrifying bacteria are cultured separately, which can rapidly enrich denitrifying and phosphorus removal bacteria and avoid sludge age conflict. At the same time, the bioreactor of the present invention uses a sequencing batch reactor as a reaction tank for denitrification and phosphorus removal and a sludge pre-sedimentation tank, which can be used for two purposes.

[0037] (4) Through the design of the present invention, the adjustment tank can operate the reaction under three conditions, with high nitrogen and phosphorus removal efficiency, avoiding the imbalance of nitrogen and phosphorus ratio that affects the treatment effect. The denitrification of nitrogen by biofilm in the anoxic tank can be further denitrified, improving efficiency. The wastewater treated by the bioreactor of the present invention has less suspended solids, and there is no need for secondary sedimentation treatment and sludge external return in the traditional process. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the cross-sectional structure of the bioreactor based on denitrification for phosphorus removal in this invention.

[0039] Figure 2 This is another cross-sectional structural schematic diagram of the bioreactor based on denitrification phosphorus removal in this invention.

[0040] Figure 3 This is a flowchart of the simultaneous nitrogen and phosphorus removal process for wastewater in this invention.

[0041] The system includes: 1. Anaerobic tank; 21. First sequencing batch tank; 22. Second sequencing batch tank; 31. First conditioning tank; 32. Second conditioning tank; 4. Aerobic tank; 5. Anoxic tank; 6. Stirring device; 7. Water distribution system; 81. First effluent pipeline system; 82. Second effluent pipeline system; 91. First valve; 92. Second valve; 101. First conditioning tank return pump; 102. Second conditioning tank return pump; 11. Biological packing material; 12. Aeration device; 131. First aerobic tank return pump; 132. Second aerobic tank return pump; 14. Adjustable weir gate. Detailed Implementation

[0042] To make the objectives, features, and advantages of this invention more apparent and understandable, a detailed description is provided below through specific embodiments. Many specific details are set forth in the following description to provide a thorough understanding of the invention. However, the invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below. Technical features in various embodiments of the invention can be combined appropriately without mutual conflict.

[0043] Unless otherwise specified, the operating methods in the following examples are generally performed under conventional conditions or as recommended by the manufacturer. Contents not described in detail in this specification are prior art known to those skilled in the art. Unless otherwise specified, the experimental materials used in the examples below can be purchased from conventional biochemical reagent companies.

[0044] Example 1

[0045] Specifically, a bioreactor based on denitrification for phosphorus removal is an integrated box structure in which the treatment tanks are connected by connecting valves, connecting pipes or water distribution systems, and adjacent treatment tanks share wall panels. Specifically, it includes an anaerobic tank 1, a first sequencing batch tank 21, a second sequencing batch tank 22, a first conditioning tank 31, a second conditioning tank 32, an aerobic tank 4, and an anoxic tank 5.

[0046] In this embodiment, the approximate volume ratio of the anaerobic tank 1, the first sequencing batch tank 21, the second sequencing batch tank 22, the first conditioning tank 31, the second conditioning tank 32, the aerobic tank 4, and the anoxic tank 5 is 1:5:5:1:1:4.5:0.5.

[0047] like Figure 1 and Figure 2 As shown, the outlet of anaerobic tank 1 is connected to the inlets of the first batch tank 21 and the second batch tank 22 via a water distribution system 7 (preferably a thin-walled weir-type water distribution device). The outlet of the first batch tank 21 is connected to the inlet of the first equalization tank 31. A first equalization tank return pump 101 is installed in the first equalization tank 31 to return activated sludge to anaerobic tank 1. The outlet of the first equalization tank 31 is connected to the inlet of aerobic tank 4. The outlet of the second batch tank 22 is connected to the inlet of the second equalization tank 32. A second equalization tank return pump 102 is installed to return activated sludge to the anaerobic tank 1. The outlet of the second equalization tank 32 is connected to the inlet of the aerobic tank 4. A first aerobic tank return pump 131 and a second aerobic tank return pump 132 are installed in the aerobic tank 4. The first aerobic tank return pump 131 returns the aerobic tank return liquid to the first sequencing batch tank 21, and the second aerobic tank return pump 132 returns the aerobic tank return liquid to the second sequencing batch tank 22. The outlet of the aerobic tank 4 is connected to the inlet of the anoxic tank 5, and the treated liquid in the anoxic tank 5 is output through the adjustable weir gate 14.

[0048] Anaerobic tank 1 is used to receive wastewater to be treated. A stirring device 6 is installed in anaerobic tank 1. It is also used to receive activated sludge returned from the conditioning tank. Anaerobic phosphorus release process under the action of activated sludge takes place in anaerobic tank. The anaerobic tank treatment liquid is input to the first batch tank 21 and the second batch tank 22.

[0049] The sequencing batch reactor (SBR) receives the treated effluent from the anaerobic tank and the return effluent from the aerobic tank, and conducts anoxic denitrification under influent, agitated, and pre-sedimentation conditions. Two SBRs are connected in parallel for multiple alternating cycles. In the first half of a reaction cycle, the first SBR 21 receives the treated effluent from the anaerobic tank and the return effluent from the aerobic tank, undergoes anoxic denitrification under influent conditions, and discharges the supernatant from the previous cycle into the aerobic tank. The remaining treated effluent enters the first conditioning tank 31. Simultaneously, the connecting parts between the second SBR 22 and the anaerobic tank 1 and the aerobic tank 4 are closed. Agitation is then carried out sequentially within this SBR. The reaction cycle involves two phases: 1) anoxic denitrification under stirring and pre-sedimentation conditions; 2) the connection between the first sequencing batch tank 21 and the anaerobic tank 1 and aerobic tank 4 is closed, and anoxic denitrification under stirring and pre-sedimentation conditions is carried out sequentially within the sequencing batch tank. Simultaneously, the connection between the second sequencing batch tank 22 and the anaerobic tank 1 and aerobic tank 4 is opened, receiving the treated effluent from the anaerobic tank and the return effluent from the aerobic tank, and conducting anoxic denitrification under influent conditions. The supernatant from the previous cycle is discharged into the aerobic tank 4, and the remaining treated effluent enters the second conditioning tank 32. After one reaction cycle ends, the cycle repeats to the next.

[0050] The first conditioning tank 31 and the first sequencing batch tank 21 are connected in series and always connected. The second conditioning tank 32 and the second sequencing batch tank 22 are connected in series and always connected. The activated sludge in the conditioning tank is returned to the anaerobic tank 1, and the supernatant is discharged into the aerobic tank 4. The first conditioning tank 31, the first sequencing batch tank 21, the second conditioning tank 32 and the second sequencing batch tank 22 are equipped with stirring devices 6, and the first conditioning tank 31 and the second conditioning tank 32 are equipped with aeration devices 12.

[0051] The aerobic tank 4 is used to receive the effluent from the first batch tank 21, the second batch tank 22, the first conditioning tank 31, and the second conditioning tank 32. The aerobic tank is equipped with biological packing material 11, on which a microbial film is cultivated. The microorganisms carry out aerobic carbonization and / or nitrification reactions in the aerobic tank. The aerobic tank 4 is also equipped with a sludge discharge device.

[0052] The anoxic tank 5 is used to receive the treated liquid from the aerobic tank. The anoxic tank 5 is equipped with biological packing material 11, on which a microbial film is cultivated. The microorganisms carry out anoxic denitrification reaction in the anoxic tank. The anoxic tank 5 is also equipped with a sludge removal device.

[0053] Furthermore, the wastewater to be treated is fed into the aforementioned bioreactor based on denitrification and phosphorus removal for simultaneous nitrogen and phosphorus removal. The flow chart is as follows: Figure 3 As shown;

[0054] The first half of a reaction cycle:

[0055] First, the wastewater to be treated enters the anaerobic tank. Simultaneously, the activated sludge returned from the first equalization tank 31 is returned to the anaerobic tank 1 via the first equalization tank return pump 101. In the anaerobic tank 1, anaerobic adsorption of organic matter and phosphorus release reactions occur. Then, the anaerobic tank treated liquid enters the first sequencing batch tank 21. At the same time, the aerobic tank treated liquid enters the first sequencing batch tank 21 via the first aerobic tank return pump 131, where anoxic denitrification and phosphorus removal reactions occur under influent conditions. Simultaneously, the treated liquid from the previous sequencing batch reaction in the first sequencing batch tank 21... The water flows into the first equalization tank 31, and after reaction in the first equalization tank 31, it enters the anaerobic tank 1 for circulation via the first equalization tank return pump 101. Depending on the water quality and operating conditions in the first equalization tank 31, the reaction is carried out under agitation conditions (anoxic reaction), aeration conditions (anoxic reaction), or settling. At the same time, the supernatant of the treated liquid from the previous batch reaction is discharged into the aerobic tank 4 through the first effluent pipeline system 81. Aerobic carbonization and nitrification reactions occur in the aerobic tank 4, and the treated liquid from the aerobic tank enters the anoxic tank 5 for anoxic denitrification reaction. Meanwhile, in the corresponding second batch tank 22, anoxic denitrification and phosphorus removal process is carried out first under agitation conditions, followed by a pre-sedimentation process and anoxic reaction during the pre-sedimentation process. The second effluent pipeline system 82 and the second valve 92 are closed, and the second equalization tank return pump 102 in the second equalization tank 32 and the second aerobic tank return pump 132 in the aerobic tank 4 are closed.

[0056] The second half of a reaction cycle:

[0057] The first batch tank 21, the first effluent pipeline system 81, the first valve 91, the first equalization tank return pump 101, and the first aerobic tank return pump 131 are interchanged with the second batch tank 22, the second effluent pipeline system 82, the second valve 92, the second equalization tank return pump 102, and the second aerobic tank return pump 132. This cycle is repeated to continuously treat sewage.

[0058] The specific process is as follows:

[0059] (1) The wastewater to be treated is fed into the anaerobic tank and mixed with the activated sludge returned from the adjustment tank to carry out anaerobic phosphorus release reaction under anaerobic conditions.

[0060] (2) The anaerobic treatment liquid obtained in step (1) is mixed with the aerobic return liquid and fed into different sequencing batch reactors for multiple alternating reactions. In the first half of a reaction cycle, the connecting parts between one sequencing batch reactor and the anaerobic and aerobic reactors are opened, and the sequencing batch reactor and the conditioning tank are always connected. After receiving the anaerobic treatment liquid and the aerobic return liquid, the anoxic denitrification reaction is carried out under influent conditions, and the original supernatant in the sequencing batch reactor is discharged into the aerobic reactor. The remaining liquid enters the conditioning tank corresponding to the sequencing batch reactor. At the same time, the connecting parts between another sequencing batch reactor and the anaerobic and aerobic reactors are closed, and the connecting parts between the conditioning tank corresponding to the sequencing batch reactor and the anaerobic reactor are closed. The sequencing batch reactor and the conditioning tank are always connected. The original anaerobic treatment liquid and aerobic return liquid in the reactor undergo anoxic denitrification reactions under stirring and pre-sedimentation conditions in sequence. In the second half of a reaction cycle, the operation and function of the two sequencing batch reactors are interchanged. After the end of a reaction cycle, the cycle enters the next reaction cycle.

[0061] (3) When the anoxic denitrification reaction under influent conditions is carried out in the sequencing batch tank corresponding to the equalization tank, the aeration device and the stirring device in the equalization tank are both closed. The equalization tank further treats the received liquid, so that the activated sludge is returned to the anaerobic tank and the supernatant is discharged into the aerobic tank. When the anoxic denitrification reaction under stirring conditions and pre-sedimentation conditions is carried out in the sequencing batch tank corresponding to the equalization tank, the aeration device is turned on / off and / or the stirring device is turned on / off and / or a carbon source is added to the equalization tank according to the composition of the received liquid.

[0062] (4) The supernatant discharged into the aerobic tank in step (2) or step (3) undergoes aerobic carbonization and / or nitrification under the action of aerobic biofilm;

[0063] (5) Discharge the treated liquid from the aerobic tank in step (4) into the anoxic tank to further carry out the denitrification process;

[0064] (6) Discharge the treated liquid from the anoxic tank in step (5) into the high-efficiency sedimentation tank to further remove total phosphorus and suspended solids, thus completing the simultaneous nitrogen and phosphorus removal process for wastewater.

[0065] Furthermore, in the process of simultaneous nitrogen and phosphorus removal in wastewater, the dissolved oxygen in the anaerobic tank is controlled to be <0.2 mg / L, the oxidation-reduction potential (ORP) is controlled to be <-200 mV, the dissolved oxygen in the sequencing batch reactor is controlled to be <0.5 mg / L, the dissolved oxygen in the aerobic tank is controlled to be 2-4 mg / L, and the dissolved oxygen in the anoxic tank is controlled to be <0.5 mg / L.

[0066] Furthermore, depending on the composition of the received liquid, the equalization tank is stirred, aerated, or a carbon source is added for reaction. When the total phosphorus content in the equalization tank influent is >0.5 mg / L and the nitrate nitrogen content is <3 mg / L, the aeration device in the equalization tank is turned on and the dissolved oxygen is controlled. The dissolved oxygen provided during the aeration process acts as an electron acceptor to enhance the removal of total phosphorus. When the nitrate nitrogen content in the equalization tank influent is >5 mg / L, the agitator in the equalization tank is turned on, and a carbon source is added to the equalization tank to enhance the removal of total nitrogen. Under other conditions, the aeration and agitator in the equalization tank are turned off to further precipitate activated sludge and increase the activated sludge content in the return liquid.

[0067] Example 2

[0068] As an example, the bioreactor for denitrification and phosphorus removal in this embodiment is 6.6m long, 4.8m wide, and 3m high, with a daily wastewater treatment capacity of 100m³. 3 The wastewater is municipal sewage, containing some industrial wastewater, requiring nitrogen and phosphorus removal. Water quality fluctuates significantly; using the AO process requires adding a carbon source to meet standards, while the A2N-SBR process results in excessive ammonia nitrogen and total nitrogen levels. Table 1 shows the cycle operation of the bioreactor based on denitrification for phosphorus removal in this embodiment. The reflux rate in the oxidation tank was set at 200%, and the reflux rate in the adjustment tank at 50%.

[0069] Table 1. Operation status of major unit equipment during the operating cycle.

[0070]

[0071] The results of the wastewater treatment process described above are shown in Table 2, indicating that the reactor in this embodiment can efficiently remove nitrogen and phosphorus from the wastewater.

[0072] Table 2. Water quality before and after wastewater treatment in Example 2

[0073]

[0074] Example 3

[0075] As an example, the bioreactor for denitrification and phosphorus removal in this embodiment is 6.6m long, 4.8m wide, and 3m high, with a daily wastewater treatment capacity of 80m³. 3 The wastewater is a mixture of municipal sewage and wastewater from the printing industry, requiring nitrogen and phosphorus removal. The reactor's cycle operation in this embodiment is shown in Table 3. The reflux rate in the oxidation tank is set at 200%, and the reflux rate in the adjustment tank at 50%.

[0076] Table 3. Operation status of major unit equipment during the operating cycle

[0077]

[0078] The results of the mixed wastewater after the above cycle treatment are shown in Table 4, indicating that the reactor in the example can efficiently remove nitrogen and phosphorus from the wastewater.

[0079] Table 4. Water quality before and after wastewater treatment in Example 3

[0080]

[0081] The embodiments described above provide a detailed explanation of the technical solutions of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, additions, or similar substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A wastewater simultaneous nitrogen and phosphorus removal process, characterized in that, The wastewater to be treated is fed into a bioreactor based on denitrification and phosphorus removal for simultaneous nitrogen and phosphorus removal. During the simultaneous nitrogen and phosphorus removal process, the dissolved oxygen in the anaerobic tank is controlled to be <0.2 mg / L, the oxidation-reduction potential (ORP) is controlled to be <-200 mV, the dissolved oxygen in the sequencing batch reactor is controlled to be <0.5 mg / L, the dissolved oxygen in the aerobic tank is controlled to be 2~4 mg / L, and the dissolved oxygen in the anoxic tank is controlled to be <0.5 mg / L. The bioreactor based on denitrification for phosphorus removal includes an anaerobic tank, two sequencing batch reactors, two conditioning tanks, an aerobic tank, and an anoxic tank. The anaerobic tank is used to receive wastewater to be treated and to receive activated sludge returned from the equalization tank. The anaerobic phosphorus release process under the action of activated sludge takes place in the anaerobic tank. The anaerobic tank treatment liquid is fed into different sequencing batch tanks. The sequencing batch reactor (SBR) receives the treated effluent from the anaerobic tank and the return effluent from the aerobic tank, and conducts anoxic denitrification under influent, stirred, and pre-sedimentation conditions. Two SBRs are connected in parallel for multiple alternating cycles. In the first half of a reaction cycle, one SBR receives the treated effluent from the anaerobic tank and the return effluent from the aerobic tank, undergoes anoxic denitrification under influent conditions, and discharges the supernatant from the previous cycle into the aerobic tank. The remaining treated effluent enters the corresponding equalization tank. Simultaneously, the connecting parts between the other SBR and the anaerobic and aerobic tanks are closed, and anoxic denitrification under stirred and pre-sedimentation conditions occurs sequentially within this SBR. In the second half of a reaction cycle, the operation and function of the two SBRs are interchanged. After one reaction cycle ends, the cycle begins again. Two equalization tanks are connected in series with different sequencing batch tanks. The equalization tanks and sequencing batch tanks are always connected. The activated sludge in the equalization tank is returned to the anaerobic tank, and the supernatant is discharged into the aerobic tank. The aerobic tank is used to receive the effluent from the sequencing batch tank and / or conditioning tank, and aerobic carbonization and / or nitrification reactions are carried out in the aerobic tank. The anoxic tank is used to receive the treated liquid from the aerobic tank, where further denitrification and nitrogen removal processes take place.

2. The wastewater simultaneous nitrogen and phosphorus removal process according to claim 1, characterized in that, Depending on the composition of the received liquid, the equalization tank is stirred, aerated, or a carbon source is added for reaction. When the total phosphorus content in the equalization tank influent is >0.5 mg / L and the nitrate nitrogen content is <3 mg / L, the aeration device in the equalization tank is turned on and the dissolved oxygen is controlled. The dissolved oxygen provided by the aeration process acts as an electron acceptor to enhance the removal of total phosphorus. When the nitrate nitrogen content in the equalization tank influent is >5 mg / L, the stirring device in the equalization tank is turned on and a carbon source is added to the equalization tank to enhance the removal of total nitrogen. Under other conditions, the aeration device in the equalization tank and the equalization tank are in a closed state to further precipitate activated sludge and increase the activated sludge content in the return liquid.

3. The wastewater simultaneous nitrogen and phosphorus removal process according to claim 1, characterized in that, The bioreactor based on denitrification for phosphorus removal is an integrated box structure. The treatment tanks are connected by connecting valves, connecting pipes or water distribution systems, and adjacent treatment tanks share wall panels.

4. The wastewater simultaneous nitrogen and phosphorus removal process according to claim 1, characterized in that, The anaerobic tank outlet side uses a thin-walled weir-type water distribution device to input the anaerobic tank treatment liquid into different sequencing batch tanks, and there is a liquid level difference between the anaerobic tank and the sequencing batch tank.

5. The wastewater simultaneous nitrogen and phosphorus removal process according to claim 1, characterized in that, The anaerobic tank and sequencing batch tank are equipped with stirring devices; the equalization tank is equipped with both stirring and aeration devices.

6. The wastewater simultaneous nitrogen and phosphorus removal process according to claim 1, characterized in that, The bottom of the sequencing batch tank is rectangular, and the bottom of the sequencing batch tank is connected to the adjustment tank, which is located on the outlet side of the sequencing batch tank.

7. The wastewater simultaneous nitrogen and phosphorus removal process according to claim 1, characterized in that, The aerobic tank is equipped with biological packing material on which a microbial film is cultivated, and the microorganisms carry out aerobic carbonization and / or nitrification reactions in the aerobic tank; the anoxic tank is equipped with biological packing material on which a microbial film is cultivated, and the microorganisms carry out anoxic denitrification reactions in the anoxic tank.

8. The wastewater simultaneous nitrogen and phosphorus removal process according to claim 1, characterized in that, Sludge removal devices are installed in the equalization tank, aerobic tank, and anoxic tank.

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