An improved A 2 Wastewater treatment system and method

Abstract

The application discloses an improved A / O wastewater treatment system and method with high-efficiency nitrogen and phosphorus removal 2 / O wastewater treatment system and method, and relates to the fields of wastewater biochemical treatment and high-efficiency nitrogen and phosphorus removal technology.The system comprises a biochemical tank inlet pipe, a pre-anoxic tank, an anaerobic tank, an anoxic tank, a primary aerobic tank, a secondary aerobic tank, a sludge return device, a wastewater return device and a sludge discharge device.The pre-anoxic tank, the anaerobic tank, the anoxic tank, the primary aerobic tank and the secondary aerobic tank are sequentially connected through pipelines.The sludge return device is connected with sludge outlets of the primary aerobic tank and the secondary aerobic tank respectively.The other end of the sludge return device is connected with the pre-anoxic tank.The primary aerobic tank and the secondary aerobic tank are connected with the anoxic tank through the wastewater return device.A sludge discharge device is installed at a sewage discharge port of the secondary aerobic tank.The sludge return device is specifically a sludge return pump, which can reduce operation cost and ensure stable and standard discharge of a wastewater treatment plant.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a modified A method with high-efficiency nitrogen and phosphorus removal. 2 Wastewater treatment systems and methods for / O. Background Technology

[0002] With the acceleration of urbanization and the continuous expansion of industrial production, the content of nutrients such as nitrogen and phosphorus in wastewater is increasing daily, causing serious eutrophication pollution of natural water bodies and affecting water quality safety and ecological balance. Traditional wastewater treatment processes, while effectively removing organic matter and some nitrogen and phosphorus to a certain extent, are often inefficient and costly when treating wastewater with high concentrations of nitrogen and phosphorus. Therefore, developing efficient, economical, and environmentally friendly wastewater nitrogen and phosphorus removal technologies has become a research hotspot in the current water treatment field.

[0003] Among the newly built wastewater treatment plants, A 2 / O has become the most common wastewater treatment process. This is because it operates relatively stably; the activated sludge survives in the alternating anaerobic, anoxic, and aerobic environments of the system, inhibiting the proliferation of filamentous bacteria and reducing sludge bulking. It is a relatively simple process for simultaneous nitrogen and phosphorus removal in wastewater treatment. However, due to the limitations of traditional A... 2 The / O process is a single-sludge system where nitrifying bacteria, denitrifying bacteria, and polyphosphate-accumulating bacteria grow together in the same system. This inevitably leads to conflicts between them. In actual operation, problems such as carbon source competition, sludge age discrepancies, and interference from nitrates in the returned sludge persist, making it difficult to simultaneously achieve optimal nitrogen and phosphorus removal efficiencies. Therefore, developing a highly efficient, stable, and economical modified A... 2 The / O process has significant practical implications; therefore, we propose an improved A process with high efficiency in nitrogen and phosphorus removal. 2 Wastewater treatment systems and methods for / O. Summary of the Invention

[0004] The technical problem to be solved by this invention is to overcome the shortcomings of existing methods and provide an improved A method with high efficiency in nitrogen and phosphorus removal. 2 The wastewater treatment system and method of / O can efficiently remove nitrogen and phosphorus, reduce operating costs, and ensure stable discharge of wastewater to meet standards, effectively solving the problems in the background technology.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a modified A with high efficiency in nitrogen and phosphorus removal. 2The / O wastewater treatment system includes a biological treatment tank inlet pipe, a pre-anoxic tank, an anaerobic tank, an anoxic tank, a primary aerobic tank, a secondary aerobic tank, a sludge return device, a wastewater return device, and a sludge discharge device. The pre-anoxic tank, anaerobic tank, anoxic tank, primary aerobic tank, and secondary aerobic tank are connected sequentially by pipelines. The sludge return device is connected to the sludge outlets of the primary aerobic tank and the secondary aerobic tank, respectively. The other end of the sludge return device is connected to the pre-anoxic tank. The primary aerobic tank and the secondary aerobic tank are connected to the anoxic tank through the wastewater return device. A sludge discharge device is installed at the wastewater outlet of the secondary aerobic tank.

[0006] Furthermore, the sludge return device is specifically a sludge return pump. The sludge inlet pipe of the sludge return pump is connected to the sludge outlet of the primary aerobic tank, and the sludge outlet pipe of the sludge return pump is connected to the return hole on the pre-anoxic tank. The sludge return pump facilitates sludge return.

[0007] Furthermore, the sludge discharge device is specifically a sludge discharge pipe, through which sludge is discharged.

[0008] Furthermore, a mechanical stirrer is installed inside the pre-anoxic tank, and a feeding port is provided on the anaerobic tank. A carbon source replenishment pipe is installed inside the feeding port, and carbon source replenishment is carried out by setting up the carbon source replenishment pipe.

[0009] Furthermore, a submersible mixer and a flow guide are installed at the bottom of the anoxic tank, a microporous aeration disc is installed at the bottom of the primary aerobic tank, the secondary aerobic tank is filled with PE elastic packing material, a nitrifying bacteria biofilm is attached to the surface of the PE elastic packing material, and a perforated water distributor is installed below the PE elastic packing material.

[0010] A modified A with high efficiency in nitrogen and phosphorus removal 2 The implementation method of the / O wastewater treatment system includes the following steps:

[0011] S1: The wastewater is injected into the pre-anoxic tank in stages. After injection, the wastewater is allowed to settle. Then, the mechanical agitator is started to fully mix the wastewater and sludge to carry out denitrification and eliminate nitrates in the returned sludge.

[0012] S2: After nitrate removal, wastewater is injected into the anaerobic tank. After injection, polyphosphate-accumulating bacteria gather here. At this time, carbon source is injected through the carbon source replenishment pipe to carry out fermentation and acid production, and to release phosphorus normally.

[0013] S3: After phosphorus release, the wastewater enters the anoxic tank. After entering, it waits for the wastewater to settle. Then, the submersible agitator inside the anoxic tank is started to mix the two. After mixing, denitrification is completed.

[0014] S4: The denitrified wastewater flows from the anoxic zone into the primary aerobic tank, and then the internal microporous aeration discs of the primary aerobic tank are activated for aeration. During the aeration process, due to the sufficient dissolved oxygen in the primary aerobic tank, polyphosphate-accumulating bacteria can fully absorb phosphorus, while dynamic nitrifying bacteria in the wastewater can perform denitrification.

[0015] S5: After sufficient phosphorus uptake, the wastewater enters the secondary aerobic tank through the primary aerobic tank. After entering, the wastewater is evenly passed through the nitrifying bacteria biofilm by the perforated water distributor for nitrification treatment. The mixed liquor after nitrification is returned to the anoxic zone through the wastewater return device, with a return ratio of 100-200%. Part of the sludge is discharged through the sludge discharge device, and part of it is returned to the pre-anoxic tank through the sludge return device to mix with the wastewater entering the pre-anoxic tank for further treatment, with a return ratio of 50-100%.

[0016] Furthermore, the sedimentation time of the wastewater in step S1 is 0.5 to 1 hour.

[0017] Furthermore, in step S2, the residence time of the wastewater inside the anaerobic tank is 1 to 2 hours.

[0018] Furthermore, the sedimentation time of the wastewater in step S3 is 1.5 to 3 hours.

[0019] Furthermore, the nitration treatment time in steps S4 and S5 is 5.5 to 8 hours.

[0020] Compared with the prior art, the beneficial effects of the present invention are: the improved A has high efficiency in nitrogen and phosphorus removal. 2 The wastewater treatment system and method of / O have the following advantages:

[0021] It can effectively reduce the competition and impact between nitrifying bacteria, denitrifying bacteria, and polyphosphate-accumulating bacteria in wastewater, solving the problem of traditional A 2 The contradiction in sludge retention time in the / O single sludge system makes each functional microorganism relatively independent, so as to achieve efficient nitrogen and phosphorus removal and ensure that the effluent from the wastewater treatment plant stably meets the discharge standards. Attached Figure Description

[0022] Figure 1 This is a diagram of the wastewater treatment system of the present invention.

[0023] Figure 2 The graph shows the annual average concentration and removal rate of ammonia nitrogen at a wastewater treatment plant in Guiyang City, based on the present invention.

[0024] Figure 3 This is a graph showing the annual average concentration and removal rate of total nitrogen at a wastewater treatment plant in Guiyang City, based on the present invention.

[0025] Figure 4 This is a graph showing the average total phosphorus concentration and removal rate at a wastewater treatment plant in Guiyang City, based on the present invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] In this invention, the wastewater treatment plant A is upgraded. 2 The / O process's nitrogen and phosphorus removal capabilities of the system, on the one hand, can prevent A 2 In the / O process, the reflux of nitrifying liquor carries excessive dissolved oxygen, which inhibits denitrifying bacteria in the anoxic zone; on the other hand, it avoids the problems associated with traditional A 2 In the / O process, the contradiction between the growth cycles of functional microorganisms such as nitrifying bacteria, denitrifying bacteria, and polyphosphate-accumulating bacteria in the single sludge system enables high-efficiency nitrogen and phosphorus removal while reducing energy consumption.

[0028] Please see Figure 1-4 This embodiment provides a technical solution: a modified A with high efficiency in nitrogen and phosphorus removal. 2 The wastewater treatment system includes a biological treatment tank inlet pipe, a pre-anoxic tank, an anaerobic tank, an anoxic tank, a primary aerobic tank, a secondary aerobic tank, a sludge return device, a wastewater return device, and a sludge discharge device. The pre-anoxic tank, anaerobic tank, anoxic tank, primary aerobic tank, and secondary aerobic tank are sequentially connected by pipelines. The sludge return device is connected to the sludge outlets of the primary and secondary aerobic tanks, respectively. The other end of the sludge return device is connected to the pre-anoxic tank. The primary and secondary aerobic tanks are connected to the anoxic tank via the wastewater return device. A sludge discharge device is installed at the sludge discharge outlet of the secondary aerobic tank. A mechanical stirrer is installed inside the pre-anoxic tank. A feeding port is set on the anaerobic tank, and a carbon source replenishment pipe is installed inside the feeding port. A submersible stirrer and a flow guide are installed at the bottom of the anoxic tank. A microporous aeration disc is installed at the bottom of the primary aerobic tank. The secondary aerobic tank is filled with PE elastic packing material, and a nitrifying bacteria biofilm is attached to the surface of the PE elastic packing material. A perforated water distributor is set below the PE elastic packing material, and carbon source replenishment is carried out through the carbon source replenishment pipe.

[0029] Specifically, the sludge return device is a sludge return pump. The sludge inlet pipe of the sludge return pump is connected to the sludge outlet of the primary aerobic tank, and the sludge outlet pipe of the sludge return pump is connected to the return hole of the pre-anoxic tank. The sludge return pump facilitates sludge return.

[0030] Specifically, the sludge discharge device is a sludge discharge pipe, which is used to discharge sludge.

[0031] This invention also provides a method under an appeals system, comprising the following steps:

[0032] S1: Inject wastewater into the pre-anoxic tank in stages. After injection, wait for the wastewater to settle. Then, start the mechanical agitator to fully mix the wastewater and sludge to carry out denitrification and eliminate nitrates in the returned sludge. The wastewater settling time is 0.5 to 1 hour.

[0033] S2: After nitrate removal, the wastewater is injected into the anaerobic tank. After injection, polyphosphate-accumulating bacteria gather here. At this time, carbon source is injected through the carbon source replenishment pipe to carry out fermentation and acid production, and to release phosphorus normally. The wastewater stays in the anaerobic tank for 1 to 2 hours.

[0034] S3: After phosphorus release, the wastewater enters the anoxic tank. After entering, the wastewater waits for sedimentation, and then the submersible agitator inside the anoxic tank is started to mix the two. After mixing, denitrification is completed. The sedimentation time of the wastewater is 1.5 to 3 hours.

[0035] S4: The denitrified wastewater flows from the anoxic zone into the primary aerobic tank, and then the internal microporous aeration discs of the primary aerobic tank are activated for aeration. During the aeration process, due to the sufficient dissolved oxygen inside the primary aerobic tank, polyphosphate-accumulating bacteria can fully absorb phosphorus.

[0036] S5: After sufficient phosphorus uptake, the wastewater enters the secondary aerobic tank through the primary aerobic tank. After entering, the wastewater is evenly passed through the nitrifying bacteria biofilm by the perforated water distributor for nitrification treatment. After nitrification, the mixed liquor is returned to the anoxic zone through the wastewater return device with a return ratio of 100-200%. Part of the sludge is discharged through the sludge discharge device, and part of it is returned to the pre-anoxic tank through the sludge return device to mix with the wastewater entering the pre-anoxic tank for further treatment until it is clean. The return ratio is 50-100%, and the nitrification time is 5.5-8 hours.

[0037] The total hydraulic retention time of this invention is 8.5–14 hours, including 0.5–1 hour in the pre-anoxic tank, 1–2 hours in the anaerobic tank, 1.5–3 hours in the anoxic tank, and 5.5–8 hours in the aerobic tank. This system maintains the number of effective bacteria in each reaction tank, avoids competition between different bacteria, promotes the formation of dominant species, reduces the mixing of sludge from different bacterial genera, increases the utilization rate of carbon sources, improves the removal efficiency of nitrogen and phosphorus in wastewater, and reduces the amount of carbon source added in winter.

[0038] The present invention will be specifically described and introduced below through the following specific embodiments.

[0039] Example:

[0040] The technology of this invention has been applied to a sewage treatment plant in Guiyang City. Through testing and monitoring, the total nitrogen, total phosphorus, and ammonia nitrogen in the effluent of the sewage treatment plant have consistently met the Class A standard of the "Discharge Standard of Pollutants for Urban Sewage Treatment Plants" (GB 18918-2002). The annual average removal rate of total phosphorus has reached over 90%, and the annual average removal rate of ammonia nitrogen has reached over 97%, ultimately resulting in an annual average electricity consumption of 0.3 kWh / ton.

[0041] Comparative example:

[0042] In wastewater treatment plants with the same technology in the same region, the average annual removal rate of total phosphorus is 85-90%, while the average removal rate of ammonia nitrogen is around 95%.

[0043] Therefore, it can be seen that after adopting this patented system and method, the nitrogen and phosphorus removal efficiency of the sewage treatment plant is improved, and the operation of the sewage treatment plant is more energy-efficient and effective.

[0044] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A modified A with high efficiency in nitrogen and phosphorus removal 2 The wastewater treatment system of / O is characterized by: The system includes an inlet pipe for a biological treatment tank, a pre-anoxic tank, an anaerobic tank, an anoxic tank, a primary aerobic tank, a secondary aerobic tank, a sludge return device, a wastewater return device, and a sludge discharge device. The pre-anoxic tank, anaerobic tank, anoxic tank, primary aerobic tank, and secondary aerobic tank are connected sequentially by pipes. The sludge return device is connected to the sludge outlets of the primary aerobic tank and the secondary aerobic tank, respectively. The other end of the sludge return device is connected to the pre-anoxic tank. The primary aerobic tank and the secondary aerobic tank are connected to the anoxic tank through the wastewater return device. A sludge discharge device is installed at the wastewater outlet of the secondary aerobic tank.

2. The modified A with high efficiency in nitrogen and phosphorus removal according to claim 1 2 The wastewater treatment system of / O is characterized by: The sludge return device is specifically a sludge return pump. The sludge inlet pipe of the sludge return pump is connected to the sludge outlet of the primary aerobic tank, and the sludge outlet pipe of the sludge return pump is connected to the return hole of the pre-anoxic tank.

3. The improved A according to claim 1, which has high efficiency in nitrogen and phosphorus removal. 2 The wastewater treatment system of / O is characterized by: The sludge discharge device is specifically a sludge discharge pipe.

4. The improved A with high efficiency in nitrogen and phosphorus removal according to claim 1 2 The wastewater treatment system of / O is characterized by: The pre-anoxic tank is equipped with a mechanical stirrer, and the anaerobic tank is equipped with a feeding port, inside which a carbon source replenishment pipe is installed.

5. The improved A according to claim 1, which has high efficiency in nitrogen and phosphorus removal. 2 The wastewater treatment system of / O is characterized by: The bottom of the anoxic tank is equipped with a submersible mixer and a flow guide tube. The bottom of the primary aerobic tank is equipped with a microporous aeration disc. The secondary aerobic tank is filled with PE elastic packing material, and nitrifying bacteria biofilm is attached to the surface of the PE elastic packing material. A perforated water distributor is installed below the PE elastic packing material.

6. A modified A with high efficiency in nitrogen and phosphorus removal according to any one of claims 1-5 2 The method for implementing a wastewater treatment system of / O is characterized by: Includes the following steps: S1: The wastewater is injected into the pre-anoxic tank in stages. After injection, the wastewater is allowed to settle. Then, the mechanical agitator is started to fully mix the wastewater and sludge to carry out denitrification and eliminate nitrates in the returned sludge. S2: After nitrate removal, wastewater is injected into the anaerobic tank. After injection, polyphosphate-accumulating bacteria gather here. At this time, carbon source is injected through the carbon source replenishment pipe to carry out fermentation and acid production, and to release phosphorus normally. S3: After phosphorus release, the wastewater enters the anoxic tank. After entering, it waits for the wastewater to settle. Then, the submersible agitator inside the anoxic tank is started to mix the two. After mixing, denitrification is completed. S4: The denitrified wastewater flows from the anoxic zone into the primary aerobic tank, and then the internal microporous aeration discs of the primary aerobic tank are activated for aeration. During the aeration process, due to the sufficient dissolved oxygen inside the primary aerobic tank, polyphosphate-accumulating bacteria can fully absorb phosphorus. S5: After sufficient phosphorus uptake, the wastewater enters the secondary aerobic tank through the primary aerobic tank. After entering, the wastewater is evenly passed through the nitrifying bacteria biofilm by the perforated water distributor for nitrification treatment. The mixed liquor after nitrification is returned to the anoxic zone through the wastewater return device, with a return ratio of 100-200%. Part of the sludge is discharged through the sludge discharge device, and part of it is returned to the pre-anoxic tank through the sludge return device to mix with the wastewater entering the pre-anoxic tank for further treatment, with a return ratio of 50-100%.

7. A modified A with high efficiency in nitrogen and phosphorus removal according to claim 6 2 The method for implementing a wastewater treatment system of / O is characterized by: The sedimentation time for wastewater in step S1 is 0.5 to 1 hour.

8. A modified A with high efficiency in nitrogen and phosphorus removal according to claim 6 2 The method for implementing a wastewater treatment system of / O is characterized by: In step S2, the wastewater stays in the anaerobic tank for 1 to 2 hours.

9. A modified A with high efficiency in nitrogen and phosphorus removal according to claim 6 2 The method for implementing a wastewater treatment system of / O is characterized by: The sedimentation time for wastewater in step S3 is 1.5 to 3 hours.

10. A modified A with high efficiency in nitrogen and phosphorus removal according to claim 6 2 The method for implementing a wastewater treatment system of / O is characterized by: The nitration treatment time in steps S4 and S5 is 5.5 to 8 hours.

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