Heterotrophic denitrification device and system for advanced nitrogen removal of petrochemical high-salinity wastewater

Abstract

The utility model discloses a heterotrophic denitrification device and a heterotrophic denitrification system for deep denitrification of petrochemical high-salinity wastewater, aims to solve the problem of inhibition of a high-salinity environment on a heterotrophic denitrification nitrogen removal process, and provides an efficient and stable wastewater nitrogen removal solution. The device mainly comprises a salt-tolerant denitrifying flora immobilization system, a carbon source slow-release module and a reaction parameter monitoring system. The biological stability of the salt-tolerant heterotrophic denitrifying flora in a high-salt environment is improved through an immobilization technology, and sufficient nutrition supply is provided through a carbon source slow release system. The online monitoring system monitors key parameters such as pH value, dissolved oxygen, oxidation-reduction potential, salinity and pressure difference in real time to ensure optimal reaction conditions. Compared with the prior art, the device disclosed by the utility model can be used for efficiently and stably removing nitrogen pollutants in the wastewater in a high-salinity environment, is relatively low in operation cost and is widely applied to deep denitrification of high-salinity wastewater in industries such as petrochemical industry and the like.

Description

TECHNICAL FIELD

[0001] The utility model relates to the high salt wastewater treatment technical field relates to a kind of for petrochemical high salt wastewater advanced denitrification heterotrophic denitrification device and system. BACKGROUND

[0002] With the acceleration of industrialization and the continuous advancement of urbanization, the national standard for sewage discharge is becoming increasingly stringent. High concentration of nitrogen can lead to water eutrophication and degradation of water environmental quality, thereby disrupting the water ecological balance and threatening human health. Currently, after secondary biochemical treatment of industrial wastewater, the effluent still contains high concentration of total nitrogen, far exceeding the water quality standard of surface water class IV. Therefore, industrial wastewater needs to be treated by advanced denitrification before it can meet the sewage discharge standard.

[0003] Heterotrophic denitrification is widely used in advanced denitrification process due to its high efficiency and low cost. The principle of heterotrophic denitrification is that denitrifying bacteria convert nitrate nitrogen to nitrite nitrogen, and then to nitrogen gas. This process requires organic matter to provide electron donors for heterotrophic denitrifying bacteria. Under normal circumstances, after secondary biochemical treatment of industrial wastewater, there is less carbon source available for microorganisms, and additional organic carbon source is often needed to ensure the smooth progress of the denitrification process.

[0004] The petroleum and chemical industry is a high energy consumption industry, producing a large amount of high-salinity wastewater every year. Under high-salinity conditions, the metabolic efficiency of denitrifying bacteria is affected, leading to a decrease in the utilization efficiency of carbon source and a decrease in nitrogen removal rate. In particular, high-salinity environments can reduce the performance of the denitrification system, leading to the accumulation of intermediate products such as nitrite NO-2-N, which can affect the stability of the system. High salinity increases the osmotic pressure, and microorganisms need to expend additional energy to maintain osmotic balance between the inside and outside of the cell, which can inhibit the metabolic activity of microorganisms. In addition, high-salinity environments can reduce the diversity of microbial communities, leaving only a few salt-tolerant bacteria to survive, which can reduce the stability and efficiency of the system.

[0005] Current conventional heterotrophic denitrification biological denitrification devices cannot balance the tolerance of high-salinity environments and high-efficiency denitrification capacity, especially traditional heterotrophic denitrifying bacteria are sensitive to salinity, and in high-salinity environments, there are problems such as reduced denitrification efficiency or insufficient biomass in the denitrification system. In addition, excessive addition of external carbon source can easily cause excessive reproduction of heterotrophic bacteria in the denitrification filter, causing the system to be easily clogged and requiring frequent backwashing. Based on the above problems, the present patent aims to develop a heterotrophic denitrification device for advanced denitrification of petrochemical high-salinity wastewater, to realize stable advanced denitrification of petrochemical industry wastewater, which is of great significance for promoting the stable and standard discharge of petrochemical wastewater. SUMMARY

[0006] The utility model discloses a kind of heterotrophic denitrification devices for petrochemical high-salt wastewater advanced denitrification to the above technical problems, including denitrification deep bed filter, the denitrification deep bed filter includes overflow area, denitrification area and buffer area sequentially arranged from top to bottom, heterotrophic denitrification area is provided in the denitrification area, the inside of the heterotrophic denitrification area is filled with ceramic grain, differential pressure transmitter and pH monitor are provided in the overflow area, and the side of the denitrification area and close to buffer area are provided with discharge port.

[0007] Further, the buffer area is provided with a water distribution system, a backwash water inlet pipe, a backwash air inlet pipe and a differential pressure transmitter are provided below the water distribution system, a backflow water inlet pipe and a water inlet pipe are provided below the backwash water inlet pipe and the backwash air inlet pipe, the water inlet pipe is connected with external water inlet, and emptying pipes and maintenance holes are respectively provided on both sides of the bottom end of the denitrification deep bed filter.

[0008] Further, a backwash water outlet pipe is provided on one side of the overflow area, the backwash water outlet pipe is communicated with the backwash water inlet pipe and the backwash air inlet pipe, a backflow water outlet pipe is sleeved in the backwash water outlet pipe, the backflow water outlet pipe is communicated with the backflow water inlet pipe, a water outlet weir is installed on one side of the backwash water outlet pipe, a water outlet pipe is installed on the water outlet weir, and the water outlet pipe is communicated with the water inlet pipe.

[0009] Further, salt-tolerant denitrifying bacteria are fixed in the heterotrophic denitrification area by immobilization technology, and the salt-tolerant denitrifying bacteria include salt-tolerant strains of Thiobacillus and Thruepera that are screened and domesticated.

[0010] Further, pebbles are arranged on the bottom of the ceramic grain in the heterotrophic denitrification area to support the ceramic grain.

[0011] A petrochemical high-salt wastewater advanced denitrification system using the heterotrophic denitrification device for petrochemical high-salt wastewater advanced denitrification described above, comprising an acid-alkali dosing module, a nutrient solution dosing module, a carbon source supplementing module and a water inlet pump, the water outlet of the water inlet pump is connected with the water inlet pipe on the heterotrophic denitrification device through a first connecting pipeline, and the acid-alkali dosing module, the nutrient solution dosing module and the carbon source supplementing module are connected with the first connecting pipeline through a liquid feeding pump.

[0012] Further, a static mixer is arranged on the pipeline communicated with the first connecting pipeline of the nutrient solution dosing module, a static mixer and a calibration column are arranged on the pipeline communicated with the first connecting pipeline of the carbon source supplementing module, and the static mixer connected with the carbon source supplementing module is located at the communication position of the carbon source supplementing module and the first connecting pipeline.

[0013] Further, it also comprises an online detection module and an effluent monitoring tank, the effluent monitoring tank is connected with an effluent pipe of the heterotrophic denitrification device, and the online detection module is connected with the first connecting pipe.

[0014] The utility model discloses compared with prior art has the beneficial effects of:

[0015] (1) by screening and culture of strong salt-tolerant heterotrophic denitrifying bacteria, and combining with solid loading technology, the survival ability and reaction efficiency of microorganism in high salt environment are significantly improved, and the problem of high salt to microbial activity inhibition is effectively overcome;

[0016] (2) the system is provided with a carbon source slow-release module, which can continuously supply the carbon source required by the denitrifying bacteria under low concentration conditions, thereby maintaining the normal growth and stable denitrification process of the denitrifying bacteria.

[0017] (3) through the salinity monitoring module, the system can monitor the salinity level in real time, and start the carbon source adding system when the salinity is too high, to ensure that the microorganism has sufficient nutrition, slow down the inhibition of salt on the microbial community, and improve the adaptability of the system to high-salinity wastewater;

[0018] (4) the system adopts the design of multistage partition reactor, reasonably configures the treatment function of each reaction zone, optimizes the denitrification process, significantly improves the removal efficiency of nitrogen pollutants, and effectively reduces the operation cost;

[0019] (5) the high-salinity wastewater denitrification solution provided by the utility model improves the treatment efficiency while reducing the consumption of energy and carbon source, is suitable for the advanced treatment of high-salinity wastewater, and has lower operation cost and higher stability. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is the structure schematic diagram of the advanced denitrification system of petrochemical high-salinity wastewater of the utility model.

[0021] Figure 2 It is the structure top view of the heterotrophic denitrification device of the utility model.

[0022] Figure 3 It is the structure front view of the heterotrophic denitrification device of the utility model.

[0023] Figure 4 It is the operation effect drawing of the utility model in summer to treat petrochemical high-salinity wastewater.

[0024] Figure 5 It is the operation effect drawing of the utility model in winter to treat petrochemical high-salinity wastewater.

[0025] Fig. 1: Inlet pipe; 2: water distribution system; 3: heterotrophic denitrification zone; 4: effluent weir; 5: effluent pipe; 6: backflow inlet pipe; 7: backflow effluent pipe; 8: backwash inlet pipe; 9: backwash air inlet pipe; 10: backwash effluent pipe; 11: emptying pipe; 12: differential pressure transmitter; 13: pH monitor; 14: discharge port; 15: manhole. DETAILED DESCRIPTION

[0026] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0027] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" and the like are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features limited by "first", "second" and the like can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0028] In the description of the present application, it should be noted that, unless otherwise specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the communication between two elements. For ordinary skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0029] Embodiment: As Figures 1-3As shown, a kind of heterotrophic denitrification device for petrochemical high-salinity wastewater advanced denitrification, heterotrophic denitrification device adopts from bottom to top mode operation, the water inlet of the bottom end of heterotrophic denitrification device, water outlet at upper end, heterotrophic denitrification device can be in the wastewater environment of total chloride concentration range 2000~4000mg / L Stable operation, including denitrification deep bed filter, denitrification deep bed filter includes by upper to lower sequentially arranged overflow area, denitrification zone and buffer zone, denitrification zone is provided with heterotrophic denitrification zone 3, the inside of heterotrophic denitrification zone 3 is filled with ceramsite, the bottom of the inside of heterotrophic denitrification zone 3 is provided with pebble for ceramsite support, overflow area is provided with differential pressure transmitter 12 for monitoring the flow pressure difference of water inlet and water outlet point of heterotrophic denitrification device and pH monitor 13 for monitoring the pH value of heterotrophic denitrification device, one side of denitrification zone and close to buffer zone is provided with unloading port 14 for emptying the filler in system when heterotrophic denitrification device needs to replace filler or system needs to overhaul.

[0030] Buffer zone is provided with water distribution system 2 for uniformly distributing petrochemical high-salinity wastewater into heterotrophic denitrification zone 3, the lower side of water distribution system 2 is provided with backwash water inlet pipe 8 for water backwash of heterotrophic denitrification device, backwash gas inlet pipe 9 for gas backwash and differential pressure transmitter 12 for monitoring the flow pressure difference of water inlet and water outlet point of heterotrophic denitrification device, through the monitoring of differential pressure transmitter 12, when the pressure monitored by differential pressure transmitter 12 exceeds 0.02Mpa, backwash is carried out, first, air washing is carried out through backwash gas inlet pipe 9 for 5 minutes, then, air-water combined backwash is carried out through backwash water inlet pipe 8 and backwash gas inlet pipe 9 for 10 minutes, finally, clean water is used for 10 minutes, the bottom end of one side of lower buffer zone, which is provided with backwash water inlet pipe 8 and backwash gas inlet pipe 9, is provided with backflow water inlet pipe 6 for use in the early domestication stage of heterotrophic denitrification device to make part of the effluent backflow and water inlet pipe 1 for connecting petrochemical high-salinity wastewater into heterotrophic denitrification device, water inlet pipe 1 is connected with external water inlet, the two sides of the bottom end of denitrification deep bed filter are respectively provided with emptying pipe 11 for emptying wastewater in device when heterotrophic denitrification device is overhauled and overhaul hole 15 for use when heterotrophic denitrification device is overhauled.

[0031] One side of overflow area is provided with backwash effluent pipe 10 for discharging wastewater when air-water backwash is carried out on heterotrophic denitrification device, backwash effluent pipe 10 is communicated with backwash water inlet pipe 8 and backwash gas inlet pipe 9, backwash effluent pipe 10 is sleeved with backflow effluent pipe 7 for part of the effluent in the early domestication stage of heterotrophic denitrification device, backflow effluent pipe 7 is communicated with backflow water inlet pipe 6, one side of backwash effluent pipe 10 is installed with effluent weir 4 for buffer effluent of heterotrophic denitrification device, effluent weir 4 is installed with effluent pipe 5 for effluent of heterotrophic denitrification device, effluent pipe 5 is communicated with water inlet pipe 1.

[0032] The salt-tolerant denitrifying bacteria are fixed in the heterotrophic denitrification zone 3 by the immobilization technology, and the salt-tolerant denitrifying bacteria include the salt-tolerant strains of Thiobacillus and Thruepera which are screened and domesticated.

[0033] As shown in Figure 1 A petrochemical high-salinity wastewater deep denitrification system of a heterotrophic denitrification device for deep denitrification of petrochemical high-salinity wastewater, as shown in the figure, comprises an acid-alkali dosing module, a nutrient liquid dosing module, a carbon source supplementing module, an online detection module, a water outlet monitoring tank and a water inlet pump. The water inlet pump makes the petrochemical high-salinity wastewater enter the heterotrophic denitrification device through a first connecting pipeline. The acid-alkali dosing module, the nutrient liquid dosing module and the carbon source supplementing module are all connected with the first connecting pipeline through liquid feeding pumps. The water outlet monitoring tank is connected with the water outlet pipe of the heterotrophic denitrification device. The water outlet monitoring tank is used for collecting and monitoring the total nitrogen content of the water outlet of the heterotrophic denitrification device. The online detection module is connected with the first connecting pipeline for real-time monitoring of the water quality in the first connecting pipeline, and adjusting the operation of the denitrification module according to the monitored data to optimize the denitrification efficiency.

[0034] The main components of the acid-alkali dosing module are sodium hydroxide and hydrochloric acid, so that the pH of the raw water entering the heterotrophic denitrification device is maintained between 7.0 and 8.0, ensuring the smooth progress of the heterotrophic denitrification.

[0035] A static mixer is arranged on the pipeline through which the nutrient liquid dosing module communicates with the first connecting pipeline. The nutrient liquid in the nutrient liquid dosing module mainly comprises 180.0 mg / L of KI, 150.0 mg / L of FeCl3·6H2O, 150.0 mg / L of H3BO3, 150.0 mg / L of CoCl2·6H2O, 60.0 mg / L of Na2MoO4·2H2O, 120.0 mg / L of MnCl2·4H2O, 30.0 mg / L of CuSO4·5H2O, 120.0 mg / L of ZnSO4·7H2O and 1000.0 mg / L of EDTA. The nutrient liquid mainly provides the microorganisms in the heterotrophic denitrification module with necessary trace elements.

[0036] A static mixer and a calibration column are arranged on the pipeline through which the carbon source supplementing module communicates with the first connecting pipeline. The static mixer connected with the carbon source supplementing module is located at the communication position of the carbon source supplementing module and the first connecting pipeline. The carbon source supplementing module is used for supplementing external carbon source when the salinity of the water inlet is higher than 3000 mg / L or in a low-temperature environment, so as to prevent the denitrification performance of the heterotrophic denitrification device from deteriorating and to strengthen the denitrification performance of the heterotrophic denitrification device.

[0037] Working principle: High-salt petrochemical wastewater enters the heterotrophic denitrification unit through an influent pump. An online monitoring module is installed on the pipeline from the influent pump to the heterotrophic denitrification unit to monitor the influent pH, dissolved oxygen, oxidation-reduction potential, and salinity. If the influent salinity does not exceed 3000 mg / L, the nutrient solution dosing module, along with the high-salt petrochemical wastewater, enters the heterotrophic denitrification unit through a static mixer. If the influent salinity exceeds 3000 mg / L in the heterotrophic denitrification zone, the carbon source replenishment module is activated, adding sodium acetate liquid carbon source according to a C / N=4 condition. Subsequently, the nutrient solution dosing module, along with the high-salt petrochemical wastewater, enters the heterotrophic denitrification unit through a static mixer. The influent enters from the bottom of the heterotrophic denitrification unit and is discharged through the upper outlet pipe 5, entering the effluent monitoring tank. The effluent from the heterotrophic denitrification unit is monitored daily to check whether the total nitrogen index meets the standards.

[0038] For example, the pilot-scale heterotrophic denitrification unit for deep denitrification of petrochemical high-salt wastewater was put into operation for the first time at the wastewater treatment plant in the petrochemical industrial park. The influent of the heterotrophic denitrification unit was the effluent after ozone oxidation technology. The influent water temperature of the heterotrophic denitrification unit was 28℃. The water quality is shown in Table 1.

[0039] Table 1. Influent Water Quality of Heterotrophic Denitrification Advanced Nitrogen Desorption Unit

[0040]

[0041] According to the Class B standard of my country's "Discharge Standard of Pollutants for Urban Wastewater Treatment Plants" (GB18918-2002), the total nitrogen limit for effluent is 20 mg / L, while the Class A standard stipulates that the total nitrogen limit for effluent is 15 mg / L. Therefore, it is evident that the effluent from this petrochemical industrial park, after secondary biological treatment and ozone oxidation treatment, is unlikely to meet the Class B discharge standard.

[0042] After treatment by a heterotrophic denitrification unit, the total nitrogen removal rate of high-salt petrochemical wastewater can be maintained at over 70%, the TN concentration in the effluent is below 15 mg / L, and the total nitrogen in the effluent generally meets the Class B standard, with some cases reaching the Class A standard.

[0043] from Figure 4 The data results show that, Figure 4 Figure a shows the total nitrogen concentration in the influent and effluent, while Figure b shows the total nitrogen removal rate of the heterotrophic denitrification unit. This pilot-scale and industrial-scale heterotrophic denitrification unit can effectively achieve deep denitrification of saline petrochemical wastewater. This integrated unit has significant advantages and promising applications for denitrification of saline petrochemical wastewater effluent.

[0044] For example, the pilot-scale heterotrophic denitrification unit for deep denitrification of petrochemical high-salt wastewater underwent its second formal operation at the wastewater treatment plant in the petrochemical industrial park. The water temperature during this stage was 15℃, and the main focus was on investigating the impact of the integrated heterotrophic denitrification unit on denitrification performance under low-temperature conditions in winter.

[0045] The influent to the heterotrophic denitrification unit is the effluent after ozone oxidation technology, and the water quality is shown in Table 2.

[0046]

[0047] According to the Class B standard of my country's "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants" (GB18918-2002), the total nitrogen limit for effluent is 20 mg / L, while the Class A standard stipulates that the total nitrogen limit for effluent is 15 mg / L. Therefore, it is evident that the effluent from this petrochemical industrial park, after secondary biological treatment and ozone oxidation treatment, is unlikely to meet the Class B discharge standard.

[0048] After treatment by a heterotrophic denitrification unit, the total nitrogen removal rate of high-salt petrochemical wastewater can be maintained at over 65%, and the TN concentration in the effluent can still be kept below 15 mg / L. The total nitrogen in the effluent generally meets the Class B standard, and in some cases, it can meet the Class A standard.

[0049] from Figure 5 The data results show that, Figure 5 Figure a shows the total nitrogen concentration in the influent and effluent, while Figure b shows the total nitrogen removal rate of the heterotrophic denitrification unit. This pilot-scale and industrial-scale heterotrophic denitrification unit can effectively achieve deep denitrification of saline petrochemical wastewater under low-temperature conditions in winter. This integrated unit has significant advantages and promising applications for denitrification of saline petrochemical wastewater effluent.

[0050] Furthermore, it should be noted that the shapes and names of the parts and components described in the specific embodiments described in this specification may differ. All equivalent or simple variations made based on the concept, structure, features, and principles of this utility model patent are included within the protection scope of this utility model patent. Those skilled in the art to which this utility model pertains may make various modifications or additions to the described specific embodiments or use similar methods to replace them, as long as they do not deviate from the structure of this utility model or exceed the scope defined in these claims, all of which should fall within the protection scope of this utility model.

Claims

1. A heterotrophic denitrification device for deep denitrification of petrochemical high-salinity wastewater, characterized in that: The denitrification deep bed filter comprises an overflow area, a denitrification area and a buffer area arranged in sequence from top to bottom, the denitrification area is provided with a heterotrophic denitrification area (3), the inside of the heterotrophic denitrification area (3) is filled with ceramsite, the overflow area is provided with a differential pressure transmitter (12) and a pH monitor (13), and the denitrification area is provided with a discharge port (14) on one side close to the buffer area.

2. The heterotrophic denitrification device for deep denitrification of petrochemical high-salinity wastewater according to claim 1, characterized in that: The buffer area is provided with a water distribution system (2), the lower portion of the water distribution system (2) is provided with a backwashing water inlet pipe (8), a backwashing air inlet pipe (9) and a differential pressure transmitter (12), the lower portion of the backwashing water inlet pipe (8) and the backwashing air inlet pipe (9) is provided with a backflow water inlet pipe (6) and a water inlet pipe (1), the water inlet pipe (1) is connected with external water inlet, and the two sides of the bottom end of the denitrification deep bed filter are respectively provided with a vent pipe (11) and an inspection hole (15).

3. The heterotrophic denitrification device for deep denitrification of petrochemical high-salinity wastewater according to claim 2, characterized in that: One side of the overflow area is provided with a backwashing water outlet pipe (10), the backwashing water outlet pipe (10) is in communication with the backwashing water inlet pipe (8) and the backwashing air inlet pipe (9), the backwashing water outlet pipe (10) is provided with a backflow water outlet pipe (7) in a sleeving mode, the backflow water outlet pipe (7) is in communication with the backflow water inlet pipe (6), one side of the backwashing water outlet pipe (10) is provided with a water outlet weir (4), the water outlet weir (4) is provided with a water outlet pipe (5), and the water outlet pipe (5) is in communication with the water inlet pipe (1).

4. The heterotrophic denitrification device for advanced nitrogen removal of petrochemical high-salinity wastewater of claim 3, characterized in that: The heterotrophic denitrification area (3) is fixed with salt-tolerant denitrification bacteria through a solid loading technology, the salt-tolerant denitrification bacteria comprise salt-tolerant strains of Thiobacillus and Thruepera that are selected and domesticated.

5. The heterotrophic denitrification device for advanced nitrogen removal of petrochemical high-salinity wastewater of claim 4, characterized in that: The inside of the heterotrophic denitrification area (3) is provided with pebbles for supporting the ceramsite.

6. A petrochemical high-salinity wastewater advanced denitrification system using the heterotrophic denitrification device for petrochemical high-salinity wastewater advanced denitrification according to any one of claims 1-5, characterized in that: The acid-alkali dosing module, the nutrient liquid dosing module, the carbon source supplementing module and a water inlet pump are arranged, the water outlet of the water inlet pump is connected with the water inlet pipe of the heterotrophic denitrification device through a first connecting pipeline, and the acid-alkali dosing module, the nutrient liquid dosing module and the carbon source supplementing module are connected with the first connecting pipeline through liquid feeding pumps.

7. The system for deep denitrification of petrochemical high-salinity wastewater of claim 6, wherein: A static mixer is arranged on the pipeline in communication with the first connecting pipeline of the nutrient liquid dosing module, a static mixer and a calibration column are arranged on the pipeline in communication with the first connecting pipeline of the carbon source supplementing module, and the static mixer connected with the carbon source supplementing module is located at the communication position of the carbon source supplementing module and the first connecting pipeline.

8. The system for deep denitrification of petrochemical high-salinity wastewater of claim 7, wherein: An online detection module and a water outlet monitoring tank are further arranged, the water outlet monitoring tank is connected with the water outlet pipe of the heterotrophic denitrification device, and the online detection module is connected with the first connecting pipeline.

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