A process for enhancing nitrogen removal in a wastewater treatment plant 2 System and method for enhancing denitrification capacity of an o process

Abstract

The application provides a system for improving the denitrification capacity of an A 2 / O process, and specifically comprises a biochemical tank water inlet pipe, an anaerobic zone, an anoxic zone, an aerobic zone, a nitrification liquid reflux pump, an aerobic tank water outlet pipe, a monitoring probe, and a PLC control cabinet. The biochemical tank water inlet pipe is connected to the water inlet end of the anaerobic zone. The bottom of the anaerobic zone is connected to the anoxic zone through an opening. The anoxic zone enters the aerobic zone through an opening. The aerobic zone returns to the anoxic zone through the nitrification liquid reflux pump. The monitoring probe is installed in the aerobic zone and is used for monitoring. The PLC control cabinet is electrically connected to the monitoring probe. The aerobic tank water outlet pipe is installed at the water outlet end of the aerobic zone. The system can prevent the nitrification liquid reflux in the A 2 / O process from carrying too much dissolved oxygen, which inhibits the denitrifying bacteria in the anoxic zone. In addition, the system can strengthen the biological denitrification of the A 2 / O process while reducing energy consumption.

Description

Technical Field

[0001] This invention belongs to the technical field of wastewater treatment, and particularly relates to a method for improving the performance of wastewater treatment plant A. 2 A system and method for denitrification capacity of the / O process. Background Technology

[0002] A 2 The anaerobic-oxygen (ANO) process is the most common nitrogen and phosphorus removal process in wastewater treatment plants. It has advantages such as simple process flow and good sludge settling performance. However, when sludge operates in alternating anaerobic, anoxic, and aerobic environments, conflicts arise in its ability to simultaneously remove nitrogen and phosphorus. For example, polyphosphate-accumulating bacteria have a short sludge age, while denitrifying and nitrifying bacteria have a longer optimal sludge age. In a single-sludge system, it is impossible to maximize the functions of nitrogen and phosphorus removal. The returned sludge contains nitrates, which affects the phosphorus release effect in the anaerobic zone. The nitrified liquor returned contains dissolved oxygen, which interferes with the denitrification function in the anoxic zone and affects the nitrogen removal effect.

[0003] To improve the nitrogen and phosphorus removal capacity of wastewater treatment plants, chemical phosphorus removal agents can be added at the back end of the biological treatment tank to ensure that the total phosphorus in the effluent meets the standards. However, nitrogen removal currently only has biological removal as a method. Therefore, a suitable method is needed to solve the technical problem of how to enhance the biological nitrogen removal effect by optimizing parameters such as sludge age, dissolved oxygen, and reflux ratio. Summary of the Invention

[0004] Technical Solution: To solve the above-mentioned technical problems, the present invention provides a method for improving the performance of wastewater treatment plant A. 2 The system for nitrogen removal using the / O process specifically includes a biological treatment tank inlet pipe, an anaerobic zone, an anoxic zone, an aerobic zone, a nitrification liquid return pump, an aerobic tank outlet pipe, a monitoring probe, and a PLC control cabinet. The biological treatment tank inlet pipe is connected to the inlet end of the anaerobic zone. The bottom of the anaerobic zone is connected to the anoxic zone through an opening. The anoxic zone enters the aerobic zone through an opening. The aerobic zone returns the nitrification liquid to the anoxic zone through the nitrification liquid return pump. The monitoring probe is installed in the aerobic zone for monitoring. The PLC control cabinet is electrically connected to the monitoring probe. The aerobic tank outlet pipe is installed at the outlet end of the aerobic zone.

[0005] As an improvement, the aerobic zone includes aerobic zone a, aerobic zone b, aerobic zone c, aerobic zone d, aeration discs, and electric valves; the aeration discs are located at the bottom of the aerobic zone, and each aeration disc is independently connected to the others via an electric valve; aerobic zone a, aerobic zone b, aerobic zone c, and aerobic zone d are arranged sequentially, wherein aerobic zone d is connected to the anoxic zone via a nitrification liquid return pump.

[0006] As an improvement, the electric valves include electric valve a, electric valve b, electric valve c, and electric valve d; wherein the aeration disc in aerobic zone a is electrically connected to electric valve a; the aeration disc in aerobic zone b is electrically connected to electric valve b; the aeration disc in aerobic zone c is electrically connected to electric valve c; and the aeration disc in aerobic zone d is electrically connected to electric valve d.

[0007] As an improvement, the monitoring probes include a DO monitoring probe and an ammonia nitrogen monitoring probe, which are independently installed inside the biochemical tank area and electrically connected to the PLC control cabinet.

[0008] As an improvement, a blower is also included, which is electrically connected to the PLC control cabinet and electric valves, and is also connected to the aerobic zone.

[0009] In addition, a method based on the above system is also provided, which is a smart aeration method based on the above system, specifically including:

[0010] Step 1: Set the ammonia nitrogen concentration threshold in the aerobic zone d. When the measured ammonia nitrogen concentration is greater than the threshold, the blower frequency needs to be increased to adjust the ammonia nitrogen concentration in the aerobic zone d until it is within the threshold before proceeding to the next step. When the measured ammonia nitrogen concentration is less than the threshold, the dissolved oxygen concentration needs to be monitored by the DO monitoring probe through normal transmission.

[0011] Step 2: According to the four zones in sequence, aerobic zone a, aerobic zone b, aerobic zone c, and aerobic zone d, set the dissolved oxygen (DO) concentration in each zone to decrease in a stepwise manner; and detect it using a DO monitoring probe.

[0012] Step 3: Monitor dissolved oxygen concentration in the order of aerobic zone d, aerobic zone c, aerobic zone b, and aerobic zone a. When the dissolved oxygen concentration is not within the set threshold, the dissolved oxygen concentration needs to be adjusted by adjusting the electric valve of the gas path until the zone is normal before monitoring the next aerobic zone can be carried out, until all aerobic zones are within the threshold.

[0013] As an improvement, in step one, the ammonia nitrogen concentration threshold is the effluent standard.

[0014] As an improvement, in step two, the dissolved oxygen concentration thresholds in aerobic zones a, b, c, and d are set to 3.0-4.0 mg / L, 2.0-3.0 mg / L, 1.0-2.0 mg / L, and 0.5-1.0 mg / L, respectively.

[0015] As an improvement, in step three, when the threshold of the aerobic zone is exceeded, the adjustment is made by reducing the opening of the electric valve in the corresponding area or reducing the frequency of the blower; when the threshold of the aerobic zone is lowered, the adjustment is made by increasing the opening of the electric valve.

[0016] As an improvement, it also includes setting the effluent ammonia nitrogen concentration threshold of aerobic zone d as the effluent standard. When the measured value is higher than the effluent ammonia nitrogen concentration threshold, it is determined that the ammonia nitrogen concentration threshold in aerobic zone d has been exceeded, and the work of step one is directly carried out.

[0017] Beneficial effects: The system proposed in this invention uses intelligent aeration to gradually reduce the dissolved oxygen (DO) in the aerobic tank. Nitrification can be basically completed in the aerobic zone ac, while the aeration rate is reduced in the aerobic zone d, resulting in lower DO carried in the nitrified liquid return and reducing the inhibition of denitrifying bacteria in the anoxic zone.

[0018] In addition, the intelligent aeration control method keeps the DO in each aerobic zone within a suitable range, reducing the loss of aeration volume and lowering energy consumption. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the present invention.

[0020] Figure 2 This is a control flowchart of the stepwise reduction method for DO in the aerobic tank in this invention.

[0021] Figure 3 This is a diagram showing the horizontal species accumulation at the entrance of the biochemical pool in an embodiment of the present invention.

[0022] In the diagram: 1-Biological tank inlet pipe, 2-Anaerobic zone, 3-Agitator, 4-Anoxic zone, 5-Aerobic zone a, 6-Aerobic zone b, 7-Aerobic zone c, 8-Aerobic zone d, 9-Nitrification liquid return pump, 10-Aerobic tank outlet pipe, 11-Aeration disc, 12-DO monitoring probe, 13-Ammonia nitrogen monitoring probe, 14-Electric valve a, 15-Electric valve b, 16-Electric valve c, 17-Electric valve d, 18-Blower, 19-PLC control cabinet. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below, so that those skilled in the art can better understand the advantages and features of the present invention, thereby making a clearer definition of the scope of protection of the present invention. The embodiments described in this invention are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0024] In this invention, the wastewater treatment plant A is upgraded. 2 A system with O process denitrification capability can, on the one hand, 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 can enhance A 2The / O process reduces energy consumption while simultaneously performing biological denitrification.

[0025] See Figure 1 As shown, the present invention improves the sewage treatment plant A 2 The system for nitrogen removal using the / O process includes a biological treatment tank, which mainly comprises anaerobic zone 2, anoxic zone 4, aerobic zone a 5, aerobic zone b 6, aerobic zone c 7, aerobic zone d 8, a nitrification liquor return pump 9, an aeration disc 11, a DO monitoring probe 12, an ammonia nitrogen monitoring probe 13, electric valves a 14, b 15, c 16, and d 17, a blower 18, and a PLC control cabinet 19. Wastewater, after primary treatment, enters the anaerobic zone and then flows through the anoxic and aerobic zones via an open channel. Part of the sludge from the aerobic zone d 8 is pumped back to the anoxic zone 4 via the nitrification liquor return pump, while the remaining wastewater is discharged through the biological treatment tank effluent pipe 10 for further treatment.

[0026] In this invention, the aerobic zone is divided into four areas, including aerobic zone a 5, aerobic zone b 6, aerobic zone c 7, and aerobic zone d 8.

[0027] As a specific embodiment of the present invention, an aeration disc is laid at the bottom of the aerobic zone, and the air volume of the aeration disc in each zone can be independently controlled by an electric valve on the pipeline.

[0028] The electric valves include electric valve a 14, electric valve b 15, electric valve c 16, and electric valve d 17; wherein the aeration disc 11 in aerobic zone a 5 is electrically connected to electric valve a 14; the aeration disc 11 in aerobic zone b 6 is electrically connected to electric valve b 15; the aeration disc 11 in aerobic zone c 7 is electrically connected to electric valve c 16; and the aeration disc 11 in aerobic zone d 8 is electrically connected to electric valve d 17.

[0029] As a specific embodiment of the present invention, a DO monitoring probe and an ammonia nitrogen monitoring probe are placed in each biochemical tank area, and the signals are connected to the PLC control cabinet. The opening of the electric valve and the blower are adjusted according to the current ammonia nitrogen and DO concentrations to keep the DO in the tank at the optimal level, achieve standard operation, and reduce energy consumption.

[0030] In this invention, by controlling the opening of the electric valve, the DO concentration in the aerobic zone a decreases stepwise. Specifically, the DO concentration is highest in aerobic zone a, reaching 3.0-4.0 mg / L. When the DO concentration in aerobic zone a is lower than 3.0 mg / L, the valve opening is increased. When the DO concentration is higher than 4.0 mg / L, the blower frequency is reduced, thereby controlling the DO concentration in aerobic zone d to be as low as approximately 0.5-1.0 mg / L.

[0031] When the ammonia nitrogen concentration in the aerobic zone d is greater than 0.5 mg / L, the signal is transmitted to the blower, increasing the blower frequency and increasing the air volume in the entire biological treatment tank area to ensure that the ammonia nitrogen in the effluent meets the standard.

[0032] As a specific embodiment of the present invention, the opening degree of the nitration liquid return pump is kept constant, and the internal return ratio is about 100% to prevent excessive energy consumption.

[0033] The present invention also provides a method under the above system, the specific steps of which include:

[0034] Step 1: Set the ammonia nitrogen concentration threshold in the aerobic zone d. When the measured ammonia nitrogen concentration is greater than the threshold, the DO monitoring probe should stop monitoring. The blower frequency needs to be increased to adjust the ammonia nitrogen concentration in the aerobic zone d until it is within the threshold before proceeding to the next step. When the measured ammonia nitrogen concentration is less than the threshold, the dissolved oxygen concentration needs to be monitored by the DO monitoring probe through normal transmission.

[0035] Step 2: According to the four zones in sequence, aerobic zone a, aerobic zone b, aerobic zone c, and aerobic zone d, set the dissolved oxygen (DO) concentration in each zone to decrease in a stepwise manner; and detect it using a DO monitoring probe.

[0036] Step 3: Monitor dissolved oxygen concentration in the order of aerobic zone d, aerobic zone c, aerobic zone b, and aerobic zone a. When the dissolved oxygen concentration is not within the set threshold, the dissolved oxygen concentration needs to be adjusted by adjusting the electric valve of the gas path until the zone is normal before monitoring the next aerobic zone can be carried out, until all aerobic zones are within the threshold.

[0037] In step three, when the threshold of the aerobic zone is exceeded, the opening of the electric valve in the corresponding zone is reduced to make adjustments; when the threshold of the aerobic zone is lowered, the opening of the electric valve is increased to make adjustments.

[0038] In step two, the dissolved oxygen concentration thresholds in aerobic zones a, b, c, and d are set to 3.0-4.0 mg / L, 2.0-3.0 mg / L, 1.0-2.0 mg / L, and 0.5-1.0 mg / L, respectively.

[0039] In a specific embodiment of the present invention, when the DO in aerobic zone d is below 0.5 mg / L, the valve opening is increased; when the DO is above 1.0 mg / L, the valve opening is decreased. When the DO in aerobic zone d is between 0.5 and 1.0 mg / L, the DO in aerobic zone c is continuously monitored.

[0040] If the DO in aerobic zone c is below 1.0 mg / L, increase the valve opening; if the DO is above 2.0 mg / L, decrease the valve opening. When the DO in aerobic zone c is between 1.0 and 2.0 mg / L, continue monitoring the DO in aerobic zone b.

[0041] If the DO in aerobic zone b is below 2.0 mg / L, increase the valve opening; if the DO is above 3.0 mg / L, decrease the valve opening. When the DO in aerobic zone b is between 2.0 and 3.0 mg / L, continue monitoring the DO in aerobic zone a.

[0042] If the DO in aerobic zone a is below 3.0 mg / L, increase the valve opening; if the DO is above 4.0 mg / L, reduce the blower frequency.

[0043] The following description and introduction of the present invention uses the aerobic zone as a comparative example with a dissolved oxygen concentration of one level, and the dissolved oxygen concentration decreasing stepwise as an example.

[0044] Comparative example:

[0045] In April and May 2023, at a wastewater treatment plant in Nanjing, the aeration pipes in all areas of the biological treatment tank were kept at a consistent opening level, with dissolved oxygen (DO) levels ranging from 2 to 4 mg / L. The average total nitrogen concentration in the influent was 24.40 mg / L, and in the effluent it was 6.75 mg / L, resulting in a removal rate of 72.34%.

[0046] Example 1

[0047] From June to October 2023, the wastewater treatment plant added intelligent aeration devices to the biological treatment tank, resulting in a stepwise decrease in dissolved oxygen (DO) concentration (DO) in different zones of the tank: 3.0-4.0 mg / L in aerobic zone a, 2.0-3.0 mg / L in aerobic zone b, 1.0-2.0 mg / L in aerobic zone c, and 0.5-1.0 mg / L in aerobic zone d. The average influent DO concentration was 23.80 mg / L, and the effluent DO concentration was 4.45 mg / L, achieving a removal rate of 81.30%, indicating an improvement in DO removal efficiency.

[0048] Therefore, it can be seen that after adopting the aerobic zone with a step-decreasing dissolved oxygen concentration in this invention, compared with the aerobic zone of the same concentration, the average total nitrogen concentration in the effluent is reduced, and the total nitrogen removal rate is significantly improved.

[0049] The following, in conjunction with specific embodiment 3, further introduces and explains the technology of the present invention by measuring the sludge phylum level species change accumulation map of the biological treatment tank obtained by the intelligent aeration control aerobic tank DO step reduction method in the present invention.

[0050] Example 2:

[0051] Figure 3 This is a sedimentary map showing the species changes at the phylum level in the biological treatment tank of the wastewater treatment plant from April to October 2023, as shown in Example 1. Figure 3It is evident that Proteobacteria is the main phylum in this wastewater treatment plant, and its main function is denitrification. After adopting the stepwise decrease of DO in the biological treatment tank in this invention, the abundance of denitrifying bacteria gradually increases, which also confirms that this method in this invention can improve the abundance of denitrifying bacteria and enhance the nitrogen removal effect.

[0052] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A process for enhancing the denitrification capacity of a wastewater treatment plant A 2 A process for enhancing the denitrification capacity of a wastewater treatment plant A The method is based on improving the denitrification capacity of the sewage treatment plant A 2 The intelligent aeration method is based on the system basis of the denitrification capacity of the / O process, and specifically includes: Step one: set the DO dissolved oxygen concentration in the four areas of aerobic area a (5), aerobic area b (6), aerobic area c (7), and aerobic area d (8) in a stepwise decreasing manner; detect through the DO monitoring probe; the dissolved oxygen concentration threshold values in the aerobic area a (5), aerobic area b (6), aerobic area c (7), and aerobic area d (8) are set to 3.0-4.0 mg / L, 2.0-3.0 mg / L, 1.0-2.0 mg / L, and 0.5-1.0 mg / L, respectively; Step two: set the ammonia nitrogen concentration threshold value in the aerobic area d region; when the measured ammonia nitrogen concentration is greater than the threshold value, the fan frequency or valve opening degree is no longer affected by the DO data, the blower frequency needs to be increased to adjust the ammonia nitrogen concentration in the aerobic area d region until it is within the threshold value, and then the next step is performed; when the measured ammonia nitrogen concentration is less than the threshold value, the DO content in each subarea needs to be adjusted according to the DO monitoring probe transmission value; Step three: monitor the dissolved oxygen concentration in the order of aerobic area d (8), aerobic area c (7), aerobic area b (6), and aerobic area a (5); when the monitoring value is not within the set threshold value, the dissolved oxygen concentration needs to be adjusted by adjusting the air path electric valve or the blower frequency until the region is normal, and then the monitoring of the next aerobic area can be performed; this process is repeated until all the aerobic areas are within the threshold value. The said promotion sewage treatment plant A 2 The system of denitrification ability of / O process, including biochemical pool water inlet pipe (1), anaerobic zone (2), anoxic zone (4), aerobic zone, nitrification liquid reflux pump (9), aerobic pool effluent pipe (10), monitoring probe, PLC control cabinet;The biochemical pool water inlet pipe (1) is communicated with the water inlet end of anaerobic zone (2);The bottom of anaerobic zone (2) is communicated with anoxic zone (4) through opening;The anoxic zone enters the aerobic zone through opening;The aerobic zone returns to anoxic zone (4) through nitrification liquid reflux pump (9);The monitoring probe is installed in the aerobic zone and is used for monitoring;The PLC control cabinet is electrically connected with the monitoring probe;The aerobic pool effluent pipe (10) is installed in the effluent end of aerobic zone. The aerobic area includes aerobic area a (5), aerobic area b (6), aerobic area c (7), aerobic area d (8), aeration disc (11), and electric valve; the aeration disc (11) is arranged at the bottom of the aerobic area, and each aeration branch pipe is independently connected through an electric valve; the aerobic area a (5), aerobic area b (6), aerobic area c (7), and aerobic area d (8) are sequentially arranged, and the aerobic area d is connected with the anoxic area (4) through a nitrification liquid reflux pump (9).

2. The enhanced wastewater treatment plant A of claim 1 2 A method for increasing the denitrification capacity of an / O process, characterized by: The electric valve includes electric valve a (14), electric valve b (15), electric valve c (16), and electric valve d (17); the aeration disc (11) in the aerobic area a (5) is electrically connected with the electric valve a (14); the aeration disc (11) in the aerobic area b (6) is electrically connected with the electric valve b (15); the aeration disc (11) in the aerobic area c (7) is electrically connected with the electric valve c (16); and the aeration disc (11) in the aerobic area d (8) is electrically connected with the electric valve d (17).

3. The enhanced wastewater treatment plant A of claim 1 2 A method for increasing the denitrification capacity of an / O process, characterized by: The monitoring probe includes a DO monitoring probe (12) and an ammonia nitrogen monitoring probe (13), which are independently installed in the interior of the biochemical pool region and are electrically connected with the PLC control cabinet.

4. The enhanced wastewater treatment plant A of claim 1 2 A method for increasing the denitrification capacity of an / O process, characterized by: The blower (3) is electrically connected with the PLC control cabinet and the electric valve and is connected with the aerobic area.

5. The enhanced wastewater treatment plant A of claim 1 2 A method for increasing the denitrification capacity of an / O process, characterized by: In step two, the ammonia nitrogen concentration threshold value is set below the effluent standard.

6. The enhanced wastewater treatment plant A of claim 1 2 A method for increasing the denitrification capacity of an / O process, characterized by: In step three, when the aerobic area threshold value is exceeded, the corresponding region is adjusted by reducing the electric valve opening degree or reducing the blower frequency; when the aerobic area threshold value is exceeded, the opening degree of the electric valve is increased for adjustment.

7. The enhanced wastewater treatment plant A of claim 2 2 A method for increasing the denitrification capacity of an / O process, characterized by: Also included is setting the effluent ammonia nitrogen concentration threshold value of the aerobic zone d as the effluent standard, when the measured value is higher than the effluent ammonia nitrogen concentration threshold value, it is determined that the ammonia nitrogen concentration threshold value in the aerobic zone d has been exceeded, and the work of step one is directly performed.

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