A segmented influent A / O process for deep denitrification of high-nitrogen organic wastewater: device and method

Abstract

This invention discloses a segmented influent A / O process for deep denitrification of high-nitrogen organic wastewater. The segmented influent A / O process comprises n (≥3) A / O tanks operating in series. Based on wastewater treatment plant water quality monitoring data and experience, an appropriate amount of high-COD concentration water is introduced to increase the influent C / N ratio, with continuous influent at the beginning of each A tank. Low-C / N water is introduced into A1 tank, mixed water to increase C / N is introduced into tanks 2 to n-1, and only an appropriate amount of high-COD concentration water is introduced into tank n. During system operation, the A / O tanks are monitored. n The concentrations of nitrate nitrogen and COD in the mixed liquor at the end of the tank are used to monitor the nitrogen removal status of the system. When A is detected... n When the concentration of nitrate nitrogen or COD in the final mixed liquor of the pool is too high, adjust A in real time. n The high COD concentration water in the influent pool enables deep denitrification of high-nitrogen organic wastewater. This invention fully leverages the advantages of the segmented influent A / O process, improves effluent quality, simplifies operation and control conditions, and achieves the goals of upgrading standards, saving energy, and reducing consumption.

Description

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a deep denitrification device and method for high-nitrogen organic wastewater using a segmented influent anoxic / aerobic (A / O) process. Background Technology

[0002] In the past decade or so, the state has successively promulgated or revised industrial water pollutant discharge standards for various industries. Without exception, strict total nitrogen discharge standards have been stipulated for nitrogen-containing wastewater. For ecologically fragile areas, the requirements for total nitrogen discharge are even more stringent. [Examples: Starch Industry Water Pollutant Discharge Standard (GB25461-2010), Ministry of Environmental Protection, September 2010; Dairy Industry Water Pollutant Discharge Standard (Draft for Comments), Ministry of Environmental Protection; Traditional Chinese Medicine Pharmaceutical Industry Water Pollutant Discharge Standard (GB21906-2008), Ministry of Environmental Protection, June 2008; Fermented Alcohol and Baijiu Industry Water Pollutant Discharge Standard (GB27631-2011), Ministry of Environmental Protection, October 2011; etc.]

[0003] For high-nitrogen organic wastewater with good biodegradability, such as wastewater from grain deep processing, dairy products, brewing, and traditional Chinese medicine pharmaceutical manufacturing, although their water quality parameters vary, their treatment engineering technical specifications generally recommend using a biological treatment technology based on "anaerobic + aerobic" combined with physical and chemical treatment technologies to achieve the treatment goal. In this combined technology process system, organic matter and other resources in the wastewater are mainly recovered in the form of biogas in the "anaerobic stage," while nitrogen in the wastewater is mainly removed in the "aerobic stage" located at the end of the system. However, the effluent from the "anaerobic stage" is generally high-ammonia water with a low C / N ratio. Due to insufficient carbon source in the water, the total nitrogen removal effect of the subsequent "aerobic stage" is seriously affected. At the same time, since high-ammonia water consumes a large amount of alkali in the nitrification stage, and the alkalinity of the wastewater is limited, and the system does not receive alkali replenishment from denitrification, a large amount of alkali is often added to the aeration tank to avoid excessively low pH value caused by alkali consumption due to ammonia nitrogen oxidation. The problem of "high alkali consumption and excessive total nitrogen in effluent" is a common problem for all types of high ammonia organic wastewater treatment plants. Improving this situation is not only a prerequisite for ensuring the healthy development of enterprises, but also of great significance for protecting the ecological environment.

[0004] The continuous flow segmented influent A / O process is an economical and efficient biological denitrification process for wastewater. However, since the influent in the last stage of the segmented influent A / O process usually only undergoes nitrification without denitrification, the effluent will inevitably contain a high concentration of nitrate nitrogen (the sum of nitrate nitrogen and nitrite nitrogen) when treating high ammonia nitrogen wastewater, thus affecting the effluent quality.

[0005] To fully leverage the advantages of the segmented influent A / O process and alleviate the aforementioned shortcomings, our team conducted experimental research on deep denitrification of high-nitrogen organic wastewater using corn starch wastewater as an example. In July 2021, we were granted the patent "Short-cut nitrification segmented influent A / O process for denitrification of corn starch wastewater [ZL201910316306.0]". Using this patented method, under laboratory conditions, a four-stage influent A / O process was employed, with the effluent from the anaerobic stage of the "anaerobic + aerobic" process at the enterprise's wastewater treatment plant as the primary treatment target. By adding an appropriate amount of influent from the anaerobic stage of the enterprise's wastewater treatment plant (water with a high organic matter concentration), the carbon / nitrogen (C / N) ratio of the four-stage influent A / O process was increased, achieving excellent deep denitrification results. However, in a pilot-scale experiment conducted at an enterprise site using the same four-stage influent A / O process, our team discovered the following problems with the method described in the patent:

[0006] (1) Due to the large fluctuations in the water quality of starch production wastewater, it is difficult to adjust and control the C / N ratio of the second and third stages of the four-stage A / O process and the amount of water with high organic matter concentration in the fourth stage in real time.

[0007] In the aforementioned patent [ZL201910316306.0] method, to meet the carbon source requirements of denitrification, the C / N ratio of the second and third stages of the four-stage influent A / O process and the total amount of organic matter in the fourth stage high-organic-concentration influent are required to be relatively constant. Under laboratory conditions, this patented method achieves excellent deep denitrification primarily because the test water (including the effluent from the anaerobic process and the influent from the anaerobic process with high organic matter concentration) is collected centrally from the enterprise's wastewater treatment plant within a short period, resulting in relatively stable water quality. Therefore, in the four-stage influent A / O process, the adjustment of the influent quality for the second and third stages and the control of the influent volume for the fourth stage high-organic-concentration water can be performed according to a pre-set fixed procedure. However, during the operation of the pilot-scale system at the enterprise's wastewater treatment plant, the test water used is the real-time effluent from the anaerobic process section and the real-time influent from the anaerobic process section of the enterprise's wastewater treatment plant. Due to various factors affecting the starch and its product production line (including periodic flushing of tanks during starch production, material leakage on the production line, and the quality, moisture content, and origin of corn raw materials), the quality of the enterprise's production wastewater fluctuates greatly [see Table 1 attached to the application example of this invention. During the enterprise's more than six months of testing, the chemical oxygen demand (COD) of the anaerobic process influent and effluent ranged from 2480 to 8140 mg / L and 97 to 365 mg / L, respectively, while the total nitrogen ranged from 127 to 345 mg / L and 116 to 275 mg / L, respectively]. To achieve the above-mentioned adjustment targets, it is necessary to adjust the proportion of high organic matter concentration water in the second and third stages and the influent volume of high organic matter concentration water in the fourth stage almost every day according to the actual changes in the production wastewater quality. This makes the operation and control cumbersome, the workload heavy, and often the adjustment cannot be carried out normally.

[0008] (2) Due to the unstable water quality of starch production wastewater in the enterprise station, the ammonia nitrogen concentration in the wastewater fluctuates greatly, making it difficult to achieve the denitrification in the form of short-cut nitrification and denitrification as described in patent [ZL201910316306.0].

[0009] Other high-nitrogen organic industrial wastewaters with similar water quality also exhibit significant fluctuations in water quality. Summary of the Invention

[0010] To address the aforementioned issues and fully leverage the denitrification advantages of the segmented influent A / O process, this invention, still using corn starch wastewater as an example, and based on the fluctuating characteristics of the wastewater quality in industrial plants, combined with existing operational experience, provides a "deep denitrification device and method for high-nitrogen organic wastewater using a segmented influent A / O process." This aims to provide technical support for the technological upgrading and transformation of the aerobic process section of existing high-nitrogen organic wastewater treatment plants and for the process design of new plants.

[0011] Basic idea of ​​this invention

[0012] In the "anaerobic + aerobic" process of a corn starch enterprise wastewater treatment plant, the effluent with a low C / N ratio from the anaerobic process section is referred to as the first concentration water, and the influent with a high organic matter concentration from the anaerobic process section is referred to as the second concentration water.

[0013] (1) Taking the first concentration water as the main treatment object, the traditional A / O reactor is divided into n (n≥3) sections of anoxic / aerobic (A / O) series operation;

[0014] (2) Statistical calculations were performed on the recent wastewater quality test data of the enterprise's wastewater treatment plant, and combined with experience, the proportion of second-concentration water with high organic matter concentration was introduced into the first-concentration water to increase the C / N ratio, so that the mixed water after increasing the C / N ratio could meet the average carbon source requirements of denitrification.

[0015] (3) In the segmented water intake A / O process, water is continuously introduced at the beginning of each A tank in each A section. Only water of the first concentration is introduced into tank A1, and water of the first concentration is introduced into tanks A2 to A1. n-1 After the C / N ratio of the mixed water is increased, it enters the pool and is placed in A. n Only a certain amount of second-concentration water is introduced into the pool. The amount of second-concentration water introduced is determined based on statistical calculations of recent wastewater quality test data from the enterprise's wastewater treatment plant and in combination with experience.

[0016] (4) Monitoring A n The concentrations of nitrate nitrogen and COD in the mixed liquor at the end of the tank are used to monitor the denitrification status of the system. When A is detected... n When the nitrate nitrogen concentration or COD concentration in the mixed liquor at the end of the tank is too high, the inflow rate of the second concentration water in tank An is adjusted in real time to achieve deep denitrification of corn starch wastewater.

[0017] The segmented influent A / O process for deep denitrification of high-nitrogen organic wastewater described in this invention can rationally allocate organic matter in the influent to serve denitrification, while simultaneously recovering alkalinity. Furthermore, it greatly simplifies the method described in patent [ZL201910316306.0] while achieving deep denitrification of corn starch wastewater.

[0018] Technical solution of the present invention

[0019] 1. The segmented influent A / O process for deep denitrification of high-nitrogen organic wastewater described in this invention has the following characteristics (taking a 4-stage influent A / O process device as an example):

[0020] The segmented influent A / O process for deep denitrification of high-nitrogen organic wastewater includes: a first concentration tank 1, a second concentration tank 2, a mixing tank 3, an alkali tank 4, a segmented influent A / O reactor 5, a sedimentation tank 6, a blower 28, a data processor 52, and a process controller 53.

[0021] The first concentration water tank 1 is equipped with a first concentration water inlet pipe 7, and the second concentration water inlet tank 2 is equipped with a second concentration water inlet pipe 8. The first concentration water tank 1 and the second concentration water tank 2 are respectively connected to the mixing water tank 3 through a first concentration water distribution pump 10 and a first concentration water distribution valve 11, a second concentration water distribution pump 12 and a second concentration water distribution valve 13, and a mixing water tank distribution pipe 16. The mixing water tank 3 is equipped with an online pH meter 9. The alkali tank 4 is connected to the mixing water tank 3 through an alkali dosing pump 14 and an alkali dosing valve 15.

[0022] The segmented influent A / O reactor 5 includes four A / O tanks connected in series. Tanks A2 to A3 have equal volumes, and tanks O1 to O3 have equal volumes. The volume of tanks A2 to A4 is no greater than 1 / 3 of the volume of tanks O1 to O3. The volumes of tanks A1 and O4 are no greater than 1 / 2 of the volumes of the other A tanks and the other O tanks, respectively. A stirrer 44 is provided in tanks A1 to A4, and each of tanks O1 to O3 has no fewer than two compartments along the flow direction (in this example). The system is divided into three compartments. At the end of each compartment (O1 to O3), an online DO meter 41 to 43 is installed. An aeration head 45 is installed in each compartment and in the O4 compartment. Each aeration head is connected to a corresponding aeration branch pipe. An aeration valve 31 to 40 is installed on each aeration branch pipe. The other end of each aeration branch pipe is connected to the main aeration pipe 29 through a connecting pipe. A main aeration valve 30 is installed on the main aeration pipe 29. The other end of the main aeration pipe 29 is connected to a blower 28.

[0023] The A1 tank of the segmented inlet A / O reactor 5 is equipped with an A1 tank inlet pipe 17, which extends into the tank from the top of the first end. An A1 tank inlet pump 18 and an A1 tank inlet valve 19 are installed on this inlet pipe. The other end of the inlet pipe is connected to the first concentration tank 1. Tanks A2 and A3 are respectively equipped with inlet branch pipes, which extend into the tanks from the top of the first end of the A2 and A3 tanks, respectively. An A2 tank inlet valve 19 is installed on each of these two branch pipes. Water pump 21, A2 pool inlet valve 22, and A3 pool inlet pump 23 and A3 pool inlet valve 24 are connected at their upstream ends to the main inlet pipe 20 of A2 and A3 pools. The main inlet pipe 20 is connected to the mixing tank 3. A4 pool is provided with an A4 pool inlet pipe 25, which extends into the pool from the top of the first end. A4 pool inlet pump 26 and A4 pool inlet valve 27 are provided on the inlet pipe. The other end of the A4 pool inlet pipe 25 is connected to the second concentration tank 2.

[0024] The sedimentation tank 6 is connected to the outlet pipe 46 of the segmented inlet A / O reactor 5. The sedimentation tank 6 is provided with a drain pipe 47, a sludge return pipe 48 and a sludge discharge pipe 49. The sludge return pipe 48 is provided with a sludge return pump 50 and a sludge return valve 51.

[0025] The data processor 52 contains pre-set parameters and calculation programs related to system operation control; the process controller 53 is equipped with execution programs for the first concentration water distribution pump 10, the first concentration water distribution valve 11, the second concentration water distribution pump 12, the second concentration water distribution valve 13, the alkali dosing pump 14, the alkali dosing valve 15, the A1 tank inlet pump 18, the A1 tank inlet valve 19, the A2 tank inlet pump 21, the A2 tank inlet valve 22, the A3 tank inlet pump 23, the A3 tank inlet valve 24, the A4 tank inlet pump 26, the A4 tank inlet valve 27, the blower 28, the main aeration valve 30, the O1 tank aeration valves 31~33, the O2 tank aeration valves 34~36, the O3 tank aeration valves 37~39, the O4 tank aeration valve 40, the sludge return pump 50, and the sludge return valve 51.

[0026] The signal output terminal of the online pH meter 9 is connected to the pH signal input terminal 54 of the data processor 52; the signal output terminals of the online DO meters 41-43 are connected to the DO signal input terminal 55 of the data processor 52; the data processor 52 is provided with a parameter setting and display terminal 56; the data processor signal output terminal 57 is connected to the process controller signal input terminal 58, and the process controller signal output terminal 59 is connected to the first concentration water distribution pump 10, the first concentration water distribution valve 11, and the second concentration water distribution valve 11 respectively via control signal transmission lines. Water distribution pump 12, second concentration water distribution valve 13, alkali dosing pump 14, alkali dosing valve 15, A1 tank inlet pump 18, A1 tank inlet valve 19, A2 tank inlet pump 21, A2 tank inlet valve 22, A3 tank inlet pump 23, A3 tank inlet valve 24, A4 tank inlet pump 26, A4 tank inlet valve 27, blower 28, main aeration valve 30, O1 tank aeration valves 31~33, O2 tank aeration valves 34~36, O3 tank aeration valves 37~39, O4 tank aeration valve 40, sludge return pump 50, and sludge return valve 51 are connected together.

[0027] 2. Differences between the segmented inlet A / O process described in this invention and the process described in patent [ZL201910316306.0]

[0028] Based on the pilot-scale test results and the patent [ZL201910316306.0], this invention makes the following improvements to the segmented inlet A / O process:

[0029] ① The steps of adding alkali to the first concentration tank 1 and the second concentration tank 2 and monitoring the alkalinity of the liquid in the two tanks have been eliminated. An online pH meter 9 has been added to the mixing tank 3 and the steps of adding alkali to the mixing tank 3 have been added.

[0030] ② The setting in pool O1~O has been removed. n-1 Online pH meters in the end compartments of each pool and restrictions on low dissolved oxygen concentrations in each O pool;

[0031] ③ The setting in pool O1~O has been removed. n-1 The online DO meter is located in the compartment before the end compartment of each pool in the pool, but only in pool O1~O n-1 Each tank in the pool retains an online DO meter at the end of its compartment.

[0032] 3. The technical procedures of the deep denitrification method for high-nitrogen organic wastewater using the segmented influent A / O process described in this invention (taking a four-stage influent A / O process unit as an example) include the following steps:

[0033] (1) The preparation of the influent to the segmented influent A / O reactor 5

[0034] ① Draw water of the first concentration into the first concentration water tank 1, and draw water of the second concentration into the second concentration water tank 2;

[0035] ② The first concentration water distribution pump 10 and the second concentration water distribution pump 12 draw water from the first concentration water tank 1 and the second concentration water tank 2 respectively, and mix the first concentration water and the second concentration water into the mixing water tank 3 in proportion through the first concentration water distribution valve 11, the second concentration water distribution valve 13 and the mixing water tank distribution pipe 16.

[0036] ③ The proportion λ1 of the second concentration water in the mixing tank 3 is determined by equation (1):

[0037] (1)

[0038] In the formula: C1 and C2 are the average COD concentrations of the first and second concentration waters calculated based on the measured data of COD concentrations of the first and second concentration waters of the wastewater treatment plant over the past 30 to 120 days, with the unit being mg / L;

[0039] C N The ammonia nitrogen concentration is the average value calculated based on the measured data of the first concentration of ammonia nitrogen in the wastewater treatment plant over the past 30 to 120 days, and the unit is mg / L.

[0040] For newly built wastewater treatment plants, if there is no measured data for 30 to 120 days, the average values ​​C1, C2, and C can be updated and calculated based on the measured data for the past 5 days, 15 days, 30 days, 60 days, and up to 120 days after the system has been running stably. N And the corresponding λ1 value is updated and calculated sequentially by equation (1);

[0041] ④ The ratio of the first concentration water added to the mixing tank 3 is 1-λ1;

[0042] ⑤ The alkali solution is pumped from the alkali tank 4 into the mixing water tank 3 by the alkali pump 14. The pH value of the mixed water in the mixing water tank 3 is controlled to be not less than 7.0 by adjusting the alkali valve 15. At the same time, the ratio of the total alkalinity to the total nitrogen concentration of the mixed water is greater than 4. The total alkalinity is expressed as CaCO3.

[0043] ⑥ After the system is running normally and stably, update the calculations of C1, C2, and C every 10 to 120 days. N The value is determined, and the new λ1 value is calculated using equation (1);

[0044] (2) Start-up of the segmented influent A / O reactor 5

[0045] ① The activated sludge with nitrification and denitrification functions is fed into the segmented influent A / O reactor 5, so that the average sludge concentration in the segmented influent A / O reactor 5 is 4200mg / L~4500mg / L;

[0046] ② Water is continuously fed into the A tank of each section of the segmented A / O reactor 5. The A1 tank is fed with the first concentration water from the first concentration water tank 1, the A2 and A3 tanks are fed with the mixed water from the mixing water tank 3, and the A4 tank is fed with the second concentration water from the second concentration water tank 2.

[0047] ③ Control the first three sections to have equal water intake, that is, the water intake Q1 of the first concentration water in pool A1 is equal to the water intake Q2 and Q3 of the mixed water in pools A2 to A3. The water intake Q4 of the second concentration water in pool A4 is determined according to its proportion λ2 to the water intake Q3 of the mixed water in pool A3, that is, Q4=λ2·Q3.

[0048] ④ The proportion λ2 of Q4 to Q3 is determined by equation (2):

[0049] (2)

[0050] In the formula: C N The value of C2 is the same as in equation (1);

[0051] ⑤ Following the above-mentioned water inlet method, control the total nitrogen load of the inlet water of the segmented water inlet A / O reactor 5 to gradually increase from small to large, and control the dissolved oxygen (DO) concentration in each O tank to be not less than 2 mg / L. The sludge return ratio of the system is 60%~75%. After the system stabilizes, it enters the next stage of stable operation.

[0052] (3) During the stable operation phase of the system, the operation control mode of the segmented influent A / O reactor 5

[0053] ① After the system is running stably, according to the water inlet distribution method described in step (1) and the water inlet method during system startup described in step (2), control the average sludge concentration in the segmented water inlet A / O reactor 5 to be 4200mg / L~4500mg / L, and the sludge return ratio of the system to be 60%~75%, and run continuously.

[0054] For typical corn starch wastewater with a total nitrogen concentration of 400 mg / L to 480 mg / L in the second concentration water, the total hydraulic retention time of the segmented influent A / O reactor 5 is 30 h to 31 h.

[0055] ② During system operation, the DO in the end compartments of O1~O3 tanks is controlled at 3.0mg / L~3.5mg / L. At the same time, the nitrate nitrogen concentration and COD concentration in the mixed liquor at the end of A4 tank in the segmented influent A / O reactor 5 are monitored 1 to 2 times a day.

[0056] When the nitrate nitrogen concentration in the end-of-A4 pool is found to be greater than 4 mg / L, the influent flow rate Q4 of the second concentration water in the A4 pool is appropriately increased. The increase in Q4 is based on the nitrate nitrogen concentration in the end-of-A4 pool being less than or equal to 4 mg / L. When the COD concentration in the end-of-A4 pool is found to be greater than 115 mg / L, the influent flow rate Q4 is appropriately decreased. The decrease in Q4 is based on the COD concentration in the end-of-A4 pool being less than 115 mg / L, while simultaneously satisfying the nitrate nitrogen concentration being less than or equal to 4 mg / L.

[0057] The process of adjusting the feed water to the segmented feed water A / O reactor 5 and the operation process of each step of the segmented feed water A / O reactor 5 are all controlled in real time by the process controller 53 according to the control strategy.

[0058] The relevant parameters in the feed water preparation process of the segmented feed water A / O reactor 5, such as the water quality parameters C1, C2, and C3 in equations (1) and (2) already stored in the data processor 52, are as follows: N The parameters such as the equivalent value and the limit value of the pH of the mixed water in the mixing tank 3 are all set and modified through the parameter setting and display terminal 56; the relevant parameters during the operation of the segmented influent A / O reactor 5, such as the limit value of DO concentration in the O tank and the limit value of sludge return ratio, are all set and modified through the parameter setting and display terminal 56.

[0059] Technical Principles of the Invention

[0060] The segmented influent A / O reactor has n (n≥3) A / O tanks connected in series. Water is continuously fed into the A tank at the beginning of each segment, resulting in a total of n influent points. Tank A1 only receives water of the first concentration, while tanks A2 through A... n-1The influent to the pool is a mixture of water with a certain proportion of water of a second concentration. The proportion λ1 of the second concentration water is calculated according to the aforementioned formula (1); the first n-1 influent points have equal amounts of influent, A n The pool is fed only an appropriate amount of second-concentration water, and the inflow rate of the second-concentration water is Q. n =λ2·Q n-1 λ2 is determined by the aforementioned equation (2).

[0061] A2~A determined according to the above method n-1 Organic matter and A in the pool mixed water influent n The organic matter in the second concentration water inlet of the pool can meet the requirements of A2~A n Average carbon source requirements for in-pond denitrification.

[0062] The volume of tank A1 is no more than half the volume of other tanks A. Its main function is to use the limited carbon source in the first concentration water to remove nitrate nitrogen from the returned sludge through denitrification by stirring.

[0063] The function of tank O1 is to degrade residual organic matter from the mixed liquor in tank A1 and to nitrify ammonia nitrogen through aeration; in O1~O n-1 Each tank in the pool is equipped with no fewer than two compartments along the flow direction, and the dissolved oxygen (DO) concentration in the end compartment is controlled at 3.0 mg / L to 3.5 mg / L to ensure that the ammonia nitrogen in the influent is completely oxidized.

[0064] The function of tank A2 is to utilize the organic matter in the influent to carry out denitrification of the nitrified liquid from tank O1 through stirring, while simultaneously recovering alkalinity.

[0065] The next O2~O n-1 The function of pool A3~A is the same as that of pool O1. n-1 The function of pool A2 is the same as that of pool A2, because A2~A n-1 The nitrogen load of the influent to the pool is basically the same as that of pool A1, therefore O2~O n-1 The working process of the pool is basically the same as that of the O1 pool, A3~A n-1 The working process of the pool is basically the same as that of the A2 pool.

[0066] A n The function of the pool is to utilize the organic matter in the influent to remove organic matter from O2. n-1 The nitrification liquid in the tank undergoes denitrification and nitrogen removal reaction through stirring, while simultaneously recovering alkalinity.

[0067] Since λ1 and λ2 are calculated values ​​based on previous measured water quality parameters and experience, the carbon source in the mixed water and the second concentration water in the corresponding A tank influent may not be exactly suitable for the carbon source requirements of wastewater denitrification on that day. Based on the operational experience of the pilot test at the enterprise site, when the carbon source is too high or too low, it can be adjusted by adjusting A... n The control and management of the influent flow rate of the second concentration water in the pool is resolved.

[0068] When A is detected n When the nitrate nitrogen concentration in the end-of-pipe mixture is greater than 4 mg / L, it indicates that A n If the carbon source for denitrification in the tank is insufficient, it can be addressed by appropriately increasing A. n The issue of the inflow rate of the second concentration of water in the pool was resolved; conversely, when A was monitored... n When the concentration of organic matter in the mixed liquor at the end of the pool is greater than 115 mg / L, it indicates that A n If there is an excess of denitrification carbon source in the pool, this can be addressed by appropriately reducing A. n The issue of the influent flow rate for the second concentration of water in the pool has been resolved. Since the second concentration water is high in COD, A... n The inflow to the pool is small, therefore A n The ammonia nitrogen concentration in the mixed liquor in the pool is not high, and will ultimately not affect the compliance of ammonia nitrogen and total nitrogen in the effluent.

[0069] O n The volume of the sedimentation tank should not exceed half the volume of other sedimentation tanks. Its main functions are: first, to strip nitrogen adhering to sludge particles, which is beneficial for sludge-water separation in the secondary sedimentation tank; and second, to oxidize the sludge in the A... n The process involves three steps: first, absorbing some ammonia nitrogen from the influent to ensure that the ammonia nitrogen in the effluent meets the standards; second, oxidizing any remaining organic matter to ensure that the COD in the effluent meets the standards.

[0070] Beneficial effects of the present invention

[0071] The segmented influent A / O process for deep denitrification of high-nitrogen organic wastewater described in this invention has the following advantages:

[0072] (1) The segmented influent A / O process for deep denitrification of high-nitrogen organic wastewater not only has a stable denitrification effect, but also the device and method are much simpler than the method in the aforementioned patent [ZL201910316306.0]. For high-nitrogen organic wastewater treatment plants with large water quality variations, deep denitrification can be achieved under simpler operating conditions.

[0073] (2) Taking the 4-stage influent A / O process as an example, the segmented influent A / O process device described in this invention, compared with the patent [ZL201910316306.0], eliminates the online pH meters (3 in total) installed at the end of each of the O1 to O3 pools and the online DO meters (6 in total) installed in the first two of each of the O1 to O3 pools. Instead, it only adds one online pH meter in the mixing tank 3. At the same time, it eliminates the restriction on low dissolved oxygen in each O pool, making the setup and operation of the entire device simpler and more economical.

[0074] (3) The denitrification effect of the segmented influent A / O process device and method described in this invention is better than that of the conventional segmented influent A / O process. In the operation and control of the conventional segmented influent A / O process denitrification system, under the condition of no external carbon source, when the C / N ratio of the influent is low or the influent has a suitable C / N ratio but a high ammonia nitrogen concentration, the effluent of the system will inevitably contain a high concentration of nitrate nitrogen, which will affect the effluent water quality.

[0075] The segmented influent A / O process apparatus and method described in this invention simply and reasonably adjusts the organic matter in the second concentration of water, so that A2~A n-1 Pool mixed water inlet and A n The organic matter in the second concentration water in the pool can meet the requirements of A2~A n The average carbon source requirement for nitrogen removal in the pond, and when A is monitored n When the nitrate nitrogen concentration or COD concentration in the end-of-tank mixed liquor is too high, it can be adjusted appropriately by A. n The issue of the influent volume for the second concentration of water in the pool was resolved. Pilot-scale results show that when n=4, the operation and control method of the segmented influent A / O process unit achieves stable denitrification and the effluent quality is superior to the direct discharge standard in the industry standard (GB25461-2010).

[0076] (4) The segmented water intake A / O process device and method described in this invention can achieve good energy saving and consumption reduction effects:

[0077] ① Compared with the traditional A / O denitrification process, the segmented influent A / O process device and method eliminates the internal reflux process of nitrified liquor, saving energy consumption for nitrified liquor reflux;

[0078] ② In each section of the A tank, the alkalinity produced by denitrification can be recovered and supplemented to the downstream aerobic O tank, reducing pH fluctuations and alkali addition costs in the aerobic tank.

[0079] ③ The organic matter in the influent of each A tank can be fully utilized by denitrification, which effectively reduces the energy consumption of oxidizing organic matter in the aerobic tank and improves the nitrification rate of autotrophic nitrifying bacteria. The pilot test results show that in the above four-stage influent A / O process device and method, the utilization rate of COD by denitrification in the anoxic tank is as high as 95% or more.

[0080] ④ The sludge concentration decreases along the flow direction in the segmented influent A / O reactor. Under the condition that the sludge concentration at the effluent end is the same, the average sludge concentration in the segmented influent A / O reactor is higher than that in the conventional single-influent A / O reactor, and the treatment capacity is stronger. Therefore, for the same effluent water quality standard, the segmented influent A / O process device and method can reduce the tank volume and save on infrastructure investment.

[0081] ⑤ It can effectively reduce the treatment load of the anaerobic process section of the wastewater treatment plant and the energy consumption for lifting the influent of the anaerobic reactor.

[0082] The second-concentration water used to supplement the denitrification carbon source was not treated in the anaerobic process section and was directly introduced into the staged influent A / O reactor. The organic matter in this part of the water is mainly in A2~A3. n Nitrification removes nitrogen in the tank; on the other hand, the influent lift height of the anaerobic reactor is generally greater than 10m, while the aerobic process section, located at the end of the entire wastewater treatment system, can usually draw water by gravity flow or with a very small lift height. Therefore, the method of introducing a second concentration of water to provide a carbon source for denitrification in this invention reduces both the treatment load of the anaerobic process section and the energy consumption of lifting the influent to the anaerobic process section.

[0083] Pilot-scale results show that, when using the segmented influent A / O process device and method described in this invention to treat corn starch wastewater, the proportion of the second concentration water used to supplement the denitrification carbon source in the four-stage influent A / O process device is 29-30%, which can reduce the treatment load of the anaerobic process section by 29-30% and also reduce the corresponding energy consumption for lifting the influent of the anaerobic process section.

[0084] (5) The segmented influent A / O process for deep denitrification of high-nitrogen organic wastewater described in this invention facilitates the upgrading and transformation of traditional A / O process systems. Attached Figure Description

[0085] Figure 1 A schematic diagram of the influent mode of the segmented influent A / O reactor described in this invention;

[0086] Figure 2 A schematic diagram of the segmented water intake A / O process device of the present invention (taking a 4-stage water intake as an example);

[0087] Figure 3The results of the changes in ammonia nitrogen, nitrate nitrogen, nitrite nitrogen and total nitrogen along the process flow on a certain day during the pilot test.

[0088] Figure 2 In the diagram, 1—First concentration water tank, 2—Second concentration water tank, 3—Mixed water tank, 4—Alkali tank, 5—Separate inlet A / O reactor, 6—Sedimentation tank, 7—Inlet pipe of first concentration water tank, 8—Inlet pipe of second concentration water tank, 9—Online pH meter, 10—First concentration water distribution pump, 11—First concentration water distribution valve, 12—Second concentration water distribution pump, 13—Second concentration water distribution valve, 14—Alkali dosing pump, 15—Alkali dosing valve, 16—Mixed water tank distribution pipe, 17—Inlet pipe of A1 tank, 18—Inlet pump of A1 tank, 19—Inlet valve of A1 tank, 20—Main inlet pipe of A2 and A3 tanks, 21—Inlet pump of A2 tank, 22—Inlet valve of A2 tank, 23—Inlet pump of A3 tank, 24—Inlet valve of A3 tank, 25—Inlet pipe of A4 tank, 26—Inlet pump of A4 tank, 27—A4 tank 28—Inlet valve, 29—Blower, 30—Main aeration pipe, 31-33—O1 tank aeration valve, 34-36—O2 tank aeration valve, 37-39—O3 tank aeration valve, 40—O4 tank aeration valve, 41—O1 tank online DO meter, 42—O2 tank online DO meter, 43—O3 tank online DO meter, 44—Agitator, 45—Aeration head, 46—Outlet pipe, 47—Drainage pipe, 48—Sludge return pipe, 49—Sludge discharge pipe, 50—Sludge return pump, 51—Sludge return valve, 52—Data processor, 53—Process controller, 54—pH signal input terminal, 55—DO signal input terminal, 56—Parameter setting and display terminal, 57—Data processor signal output terminal, 58—Process controller signal input terminal, 59—Process controller signal output terminal.

[0089] from Figure 3 It is evident that on this day, both pools A2 and A3 in the system still had a high concentration of nitrate nitrogen that had not been removed, indicating that the carbon source in the mixed water in pool mixing tank 2 was significantly insufficient. However, due to careful control of the inflow rate of the second concentration water in pool A4, the nitrate nitrogen concentration in the mixed solution of pool A4 was only 3.19 mg / L, and the total nitrogen in the final system effluent was only 3.41 mg / L, of which ammonia nitrogen was 0.8 mg / L, nitrate nitrogen was 2.61 mg / L, and nitrite nitrogen was 0 mg / L. Detailed Implementation

[0090] The following explanation uses a 4-stage inlet A / O process as an example:

[0091] 1. The installation of the deep denitrification device for high-nitrogen organic wastewater in the segmented influent A / O process described in this invention.

[0092] See Figure 2The segmented influent A / O process apparatus of the present invention includes a first concentration water tank 1, a second concentration water tank 2, a mixing water tank 3, an alkali solution tank 4, a segmented influent A / O reactor 5, a sedimentation tank 6, a blower 28, a data processor 52, and a process controller 53. Specific implementation methods are as follows:

[0093] (1) Setting up the feed water distribution system for the segmented feed water A / O reactor 5

[0094] The first concentration water tank 1 and the second concentration water tank 2 are respectively provided with a first concentration water tank inlet pipe 7 and a second concentration water tank inlet pipe 8; the first concentration water tank 1 and the second concentration water tank 2 are respectively connected to the mixing water tank 3 through a first concentration water distribution pump 10 and a first concentration water distribution valve 11, a second concentration water distribution pump 12 and a second concentration water distribution valve 13 and a mixing water tank distribution pipe 16, and the mixing water tank 3 is provided with an online pH meter 9; the alkali tank 4 is connected to the mixing water tank 3 through an alkali dosing pump 14 and an alkali dosing valve 15.

[0095] (2) Setup of the segmented influent A / O reactor 5 and its aeration system

[0096] The segmented influent A / O reactor 5 includes four A / O tanks connected in series. Tanks A2 to A4 have equal volumes, and tanks O1 to O3 have equal volumes. The volume of tanks A2 to A4 is no greater than 1 / 3 of the volume of tanks O1 to O3. The volumes of tanks A1 and O4 are no greater than 1 / 2 of the volumes of the other A tanks and other O tanks, respectively. A stirrer 44 is installed in tanks A1 to A4, and each of tanks O1 to O3 is equipped with a head end, a middle end, and a tail end. Each compartment has an online DO meter 41-43 at the end of each of the O1 to O3 tanks; each compartment and the O4 tank has an aeration head 45, each aeration head is connected to a corresponding aeration branch pipe, and each aeration branch pipe is equipped with an aeration valve 31-40; the other end of each aeration branch pipe is connected to the aeration main pipe 29 through a connecting pipe, and the aeration main pipe 29 is equipped with a main aeration valve 30, and the other end of the aeration main pipe 29 is connected to a blower 28.

[0097] (3) The setup of the inlet pipeline system for the segmented inlet A / O reactor 5

[0098] The segmented inlet A / O reactor 5 has an A1 tank equipped with an A1 tank inlet pipe 17, which extends into the tank from the top of the first end. An A1 tank inlet pump 18 and an A1 tank inlet valve 19 are installed on this inlet pipe, and the other end of the pipe is connected to the first concentration water tank 1. Tanks A2 and A3 are respectively equipped with inlet branch pipes, which extend into the tanks from the top of the first end of A2 and A3, respectively. An A2 tank inlet valve is installed on each of these two branch pipes. Pump 21, A2 pool inlet valve 22, A3 pool inlet pump 23, A3 pool inlet valve 24, and the upstream ends of two inlet branch pipes are connected to the main inlet pipe 20 of A2 pool and A3 pool. The main inlet pipe 20 is connected to the mixing water tank 3. A4 pool is provided with A4 pool inlet pipe 25, which extends into the pool from the top of the first end of A4 pool. A4 pool inlet pump 26 and A4 pool inlet valve 27 are provided on the inlet pipe. The other end of A4 pool inlet pipe 25 is connected to the second concentration water tank 2.

[0099] (4) Setting up the sedimentation tank 6 of the segmented influent A / O reactor 5

[0100] The sedimentation tank 6 is connected to the outlet pipe 46 of the segmented inlet A / O reactor 5. The sedimentation tank is equipped with a drain pipe 47, a sludge return pipe 48 and a sludge discharge pipe 49. The sludge return pipe 48 is equipped with a sludge return pump 50 and a sludge return valve 51.

[0101] (5) Setting up the control system for the segmented influent A / O reactor 5

[0102] The control system of the segmented influent A / O reactor 5 includes two main parts: a data processor 52 and a process controller 53. The data processor 52 contains pre-set parameters and calculation programs related to system operation control. The process controller 53 is equipped with a first concentration water distribution pump 10, a first concentration water distribution valve 11, a second concentration water distribution pump 12, a second concentration water distribution valve 13, an alkali dosing pump 14, and an alkali dosing valve 15. The execution procedures for the following pumps: A1 tank inlet pump 18, A1 tank inlet valve 19, A2 tank inlet pump 21, A2 tank inlet valve 22, A3 tank inlet pump 23, A3 tank inlet valve 24, A4 tank inlet pump 26, A4 tank inlet valve 27, blower 28, main aeration valve 30, O1 tank aeration valves 31~33, O2 tank aeration valves 34~36, O3 tank aeration valves 37~39, O4 tank aeration valve 40, sludge return pump 50, and sludge return valve 51.

[0103] The signal output terminal of the online pH meter 9 is connected to the pH signal input terminal 54 of the data processor 52; the signal output terminals of the online DO meters 41-43 are connected to the DO signal input terminal 55 of the data processor 52; the data processor 52 is provided with a parameter setting and display terminal 56; the data processor signal output terminal 57 is connected to the process controller signal input terminal 58, and the process controller signal output terminal 59 is connected to the first concentration water distribution pump 10, the first concentration water distribution valve 11, and the second concentration water distribution valve 11 respectively via control signal transmission lines. Water distribution pump 12, second concentration water distribution valve 13, alkali dosing pump 14, alkali dosing valve 15, A1 tank inlet pump 18, A1 tank inlet valve 19, A2 tank inlet pump 21, A2 tank inlet valve 22, A3 tank inlet pump 23, A3 tank inlet valve 24, A4 tank inlet pump 26, A4 tank inlet valve 27, blower 28, main aeration valve 30, O1 tank aeration valves 31~33, O2 tank aeration valves 34~36, O3 tank aeration valves 37~39, O4 tank aeration valve 40, sludge return pump 50, and sludge return valve 51 are connected together.

[0104] 2. Technical procedures of the segmented influent A / O process for deep denitrification of high-nitrogen organic wastewater

[0105] (1) The water preparation steps for the segmented water inlet A / O reactor 5

[0106] ① First concentration water is drawn from the first concentration water tank inlet pipe 7 to the first concentration water tank 1, and second concentration water is drawn from the second concentration water tank inlet pipe 8 to the second concentration water tank 2;

[0107] ② Based on the measured COD concentration data of the first and second concentration wastewater from the wastewater treatment plant over the past 30 to 120 days, calculate the average COD concentrations C1 and C2 of the first and second concentration wastewater, in mg / L; based on the measured ammonia nitrogen concentration data of the first concentration wastewater from the wastewater treatment plant over the past 30 to 120 days, calculate the average ammonia nitrogen concentration C of the first concentration wastewater. N The unit is mg / L;

[0108] ③ The calculated water quality parameters C1, C2, and C N The value is input to the data processor 52 through the parameter setting and display terminal 56; and is obtained from the formula (1) already stored in the data processor 52, namely: Calculate the proportion λ1 of the second concentration water in the mixing tank 3, and the proportion of the first concentration water added to the mixing tank is 1-λ1;

[0109] ④ After the λ1 value is confirmed, the data processor signal output terminal 57 outputs a signal to drive the process controller 53, and outputs a control signal through the process controller signal output terminal 59 to start the first concentration water distribution pump 10 and the second concentration water distribution pump 12, which draw water from the first concentration water tank 1 and the second concentration water tank 2 respectively. By adjusting and controlling the first concentration water distribution valve 11 and the second concentration water distribution valve 13, the first concentration water and the second concentration water are proportionally distributed into the mixing water tank 3 through the mixing water tank distribution pipe 16.

[0110] ⑤ Start the alkali pump 14 to dispense alkali solution from the alkali tank 4 into the mixing water tank 3. Adjust the alkali valve 15 to control the pH value of the mixed water in the mixing water tank 3 to be no less than 7.0, while ensuring that the ratio of total alkalinity to total nitrogen in the mixed water is greater than 4.0. The total alkalinity is expressed as CaCO3.

[0111] ⑥ For newly built wastewater treatment plants, if there is no measured data for 30 to 120 days, the average values ​​C1, C2, and C can be updated and calculated based on the measured data for the past 5 days, 15 days, 30 days, 60 days, and up to 120 days after the wastewater treatment plant system has been operating stably. N Each update calculates new C1, C2, and C. N After obtaining the data, adjust the influent to the A / O reactor 5 according to steps ③ to ⑤ above;

[0112] ⑦ After the system is running normally and stably, C1, C2, and C3 should be calculated and updated every 10 to 120 days according to step ② above. N value;

[0113] (2) Start-up of the segmented influent A / O reactor 5

[0114] ① The activated sludge with nitrification and denitrification functions is fed into the segmented influent A / O reactor 5, so that the average sludge concentration in the reactor is 4200mg / L~4500mg / L;

[0115] ② In the segmented A / O reactor 5, water is continuously introduced into the A tank of each A / O section. The A1 tank inlet pump 18 draws water from the first concentration tank 1 and introduces first concentration water into the A1 tank through the A1 tank inlet valve 19 and the A1 tank inlet pipe 17. The A2 tank inlet pump 21 and the A3 tank inlet pump 23 draw water from the mixing tank 3 and introduce mixed water into the A2 tank and the A3 tank through the A2 tank inlet valve 22 and the A3 tank inlet valve 24, respectively. The A4 tank inlet pump 26 draws water from the second concentration tank 2 and introduces second concentration water into the A4 tank through the A4 tank inlet valve 27 and the A4 tank inlet pipe 25.

[0116] ③ Control the first three stages to have equal water inflow, that is, the inflow volume Q1 of the first concentration water in pool A1 is equal to the inflow volumes Q2 and Q3 of the mixed water in pools A2 to A3. The inflow volume Q4 of the second concentration water in pool A4 is determined according to its proportion λ2 to the inflow volume Q3 of the mixed water in pool A3, that is, Q4 = λ2·Q3; λ2 is given by equation (2) already stored in data processor 52, that is: calculate;

[0117] ④ Following the above-mentioned water intake method, control the total nitrogen load of the water entering the segmented water intake A / O reactor 5 to gradually increase from small to large, and control the dissolved oxygen (DO) concentration in each O tank to be not less than 2 mg / L. The sludge return ratio of the system is taken as 60%~75%. After the system stabilizes, it enters the next stage of stable operation.

[0118] (3) During the stable operation phase of the system, the operation control mode of the segmented influent A / O reactor 5

[0119] ① After the system is running stably, the average sludge concentration in the reactor is controlled to be 4200mg / L~4500mg / L and the sludge return ratio of the system is 60%~75% for continuous operation, in accordance with the water supply method described in the above technical procedure (1) and the water supply method during system startup described in the above technical procedure (2).

[0120] ② For typical corn starch wastewater with a total nitrogen concentration of 400 mg / L to 480 mg / L in the second concentration water, the total hydraulic retention time of the segmented influent A / O reactor 5 is 30 h to 31 h.

[0121] ③ During system operation, the dissolved oxygen (DO) concentration in the end compartments of O1~O3 tanks is controlled at 3.0 mg / L~3.5 mg / L. At the same time, the nitrate nitrogen concentration and COD concentration in the end mixed liquor of A4 tank in the segmented influent A / O reactor 5 are monitored 1 to 2 times a day.

[0122] When the nitrate nitrogen concentration in the mixed liquor at the end of tank A4 is found to be greater than 4 mg / L, the influent flow rate Q4 of the second concentration water in tank A4 can be appropriately increased. The increase in Q4 should be based on the nitrate nitrogen concentration in the mixed liquor at the end of tank A4 being less than or equal to 4 mg / L. When the COD concentration in the mixed liquor at the end of tank A4 is found to be greater than 115 mg / L, the influent flow rate Q4 can be appropriately decreased. The decrease in Q4 should be based on the COD concentration in the mixed liquor at the end of tank A4 being less than 115 mg / L, while the nitrate nitrogen concentration is less than or equal to 4 mg / L.

[0123] Application Examples

[0124] This example is a pilot-scale test conducted on-site at the wastewater treatment plant of a large corn starch enterprise. The pilot-scale equipment is shown below. Figure 2 The water treatment capacity is approximately 1.3m³. 3 / d~1.6m3 / d, the total hydraulic retention time of the system is 30.8h. Two scenarios were considered when treating water during the experiment:

[0125] (1) The test water is the normal production wastewater of the enterprise. Its water quality and temperature are shown in Table 1 below.

[0126] Table 1. Water quality of production wastewater used in the experiment

[0127]

[0128] During the more than six-month trial, under the condition that the average total nitrogen load of the influent was 167.4 mg / L·d, the method described in this invention resulted in effluent COD, ammonia nitrogen, and total nitrogen levels all exceeding the industry standard (GB25461-2010) for direct discharge. A third-party company tested the water quality of the system's influent and effluent on a specific day of the trial. With COD concentrations of 170 mg / L, 1496 mg / L, and 4720 mg / L for the first concentration water, the mixed water, and the second concentration water, respectively, and total nitrogen concentrations of 227.36 mg / L, 232.23 mg / L, and 240.20 mg / L, respectively, the system's effluent COD was 63 mg / L, and the total nitrogen was only 12.31 mg / L.

[0129] Table 2 records the results of the experiment, excluding... Figure 3 In addition, this is another example of insufficient carbon source in the influent of pools A2 and A3.

[0130] Table 2. Changes in influent nitrogen concentration and nitrogen forms in tanks A1-A4 and O4 of the system.

[0131]

[0132] The total nitrogen in each A pool and O4 in the table is the sum of ammonia nitrogen, nitrate nitrogen and nitrite nitrogen in the pool.

[0133] As can be seen from Table 2, there were high concentrations of nitrate nitrogen remaining in pools A2 and A3, indicating that the carbon source of the mixed water in the mixing tank was insufficient on this day. However, due to the adoption of the method of the present invention, the influent flow rate of the second concentration water in pool A4 was appropriately increased, and the nitrate nitrogen concentration in pool A4 was only 1.24 mg / L, and the final total nitrogen in the effluent was only 2.54 mg / L.

[0134] (2) During this experiment, the overall concentration of pollutants in the wastewater was relatively low due to the company operating at half capacity. In the later stages of the experiment, NH4Cl was added manually to further investigate the denitrification characteristics of the segmented influent A / O process system under higher influent nitrogen load conditions. During the experiment, NH4Cl was used to increase the ammonia nitrogen concentration of the first concentration water and the mixed water, and NaHCO3 was added to increase the alkalinity of the first concentration water and the mixed water. The nitrogen concentration and alkalinity of the second concentration water were not adjusted. During the 10-day experiment, the average total nitrogen load of the system influent was 317.32 mg / L∙d, and the COD, ammonia nitrogen, and total nitrogen in the effluent were still better than the industry standard (GB25461-2010) direct discharge standard. A third-party company tested the total nitrogen of the system influent and effluent on a certain day during this experiment. Under the conditions that the total nitrogen of the first concentration water and the mixed water were 441.20 and 481.35 mg / L, respectively, the total nitrogen of the effluent was 26.74 mg / L.

[0135] The above application examples, using the treatment of corn starch wastewater as an example, further illustrate the denitrification effect of the present invention in conjunction with specific embodiments, facilitating a better understanding and application of the invention by those skilled in the art. The specific embodiments of the present invention are also applicable to the treatment of high-nitrogen organic wastewater from other grain deep processing, dairy products, brewing, and traditional Chinese medicine pharmaceutical manufacturing. It should not be considered that the specific embodiments of the present invention are limited to these descriptions; any simple modifications made to the present invention by those skilled in the art are within the scope of protection of the present invention.

[0136] This invention can provide technical support for the technological upgrading and transformation of the aerobic process section of existing starch wastewater treatment plants with "anaerobic + aerobic" biological treatment technology and similar high-nitrogen organic wastewater treatment plants, as well as for the process design of new plants.

Claims

1. A method for deep denitrification of high-nitrogen organic wastewater using a segmented influent A / O process, characterized in that: The deep denitrification method is performed using the following apparatus: The device includes a first concentration water tank (1), a second concentration water tank (2), a mixing water tank (3), an alkali tank (4), a segmented inlet A / O reactor (5), a sedimentation tank (6), a blower (28), a data processor (52), and a process controller (53); The first concentration water tank (1) is provided with a first concentration water inlet pipe (7), and the second concentration water tank (2) is provided with a second concentration water inlet pipe (8); the first concentration water tank (1) and the second concentration water tank (2) are respectively connected to the mixing water tank (3) through a first concentration water distribution pump (10) and a first concentration water distribution valve (11), a second concentration water distribution pump (12) and a second concentration water distribution valve (13), and a mixing water tank distribution pipe (16); the mixing water tank (3) is provided with an online pH meter (9); the alkali tank (4) is connected to the mixing water tank (3) through an alkali injection pump (14) and an alkali injection valve (15); The segmented influent A / O reactor (5) includes four A / O tanks connected in series: A1 / O1, A2 / O2, A3 / O3, and A4 / O4. The volumes of A2, A3, and A4 are equal, as are the volumes of O1, O2, and O3. The volume of A2, A3, and A4 is no greater than 1 / 3 of the volume of O1, O2, and O3. The volumes of A1 and O4 are no greater than 1 / 2 of the volumes of the other A and O tanks, respectively. A stirrer (44) is installed in each of the A1 to A4 tanks, and a stirrer (44) is installed along the flow direction in each of the O1 to O3 tanks. The system has at least two compartments. Each compartment at the end of the O1, O2 and O3 pools is equipped with an online DO meter (41), (42) and (43), respectively. Each compartment and the O4 pool are equipped with an aeration head (45). Each aeration head is connected to a corresponding aeration branch pipe. Each aeration branch pipe is equipped with an aeration valve (31) to (40). The other end of each aeration branch pipe is connected to the main aeration pipe (29) through a connecting pipe. The main aeration pipe (29) is equipped with a main aeration valve (30). The other end of the main aeration pipe (29) is connected to the blower (28). The A1 tank of the segmented inlet A / O reactor (5) is equipped with an A1 tank inlet pipe (17), which extends into the tank from the top of the first end of the A1 tank. An A1 tank inlet pump (18) and an A1 tank inlet valve (19) are provided on the A1 tank inlet pipe (17). The other end of the A1 tank inlet pipe (17) is connected to the first concentration water tank (1). The A2 tank and the A3 tank are respectively equipped with A2 tank inlet pipes and A3 tank inlet pipes, which extend into the tank from the top of the first end of the A2 tank and the A3 tank respectively. A2 tank inlet pump (18) and A3 tank inlet valve (19) are respectively provided on the A2 tank inlet pipe and the A3 tank inlet pipe. Pump (21), A2 pool inlet valve (22), A3 pool inlet pump (23), A3 pool inlet valve (24), the upstream ends of the A2 pool inlet pipe and the A3 pool inlet pipe are connected to the A2 pool and A3 pool inlet main pipe (20), the A2 pool and A3 pool inlet main pipe (20) are connected to the mixing water tank (3); A4 pool is provided with A4 pool inlet pipe (25), the A4 pool inlet pipe (25) extends into the pool from the top of the first end of A4 pool, the A4 pool inlet pump (26) and A4 pool inlet valve (27) are provided on the A4 pool inlet pipe (25), the other end of the A4 pool inlet pipe (25) is connected to the second concentration water tank (2); The sedimentation tank (6) is connected to the outlet pipe (46) of the segmented inlet A / O reactor (5). The sedimentation tank (6) is provided with a drain pipe (47), a sludge return pipe (48) and a sludge discharge pipe (49). The sludge return pipe (48) is provided with a sludge return pump (50) and a sludge return valve (51). The data processor (52) contains pre-set parameters and calculation programs related to the operation and control of the device; the process controller (53) is equipped with the first concentration water distribution pump (10), the first concentration water distribution valve (11), the second concentration water distribution pump (12), the second concentration water distribution valve (13), the alkali dosing pump (14), the alkali dosing valve (15), the A1 pool inlet pump (18), the A1 pool inlet valve (19), the A2 pool inlet pump (21), and the A2 pool inlet pump (22). The execution procedures of the following: pool inlet valve (22), pool inlet pump (23), pool inlet valve (24), pool inlet pump (26), pool inlet valve (27), blower (28), main aeration valve (30), pool aeration valve (31)~(33), pool aeration valve (34)~(36), pool aeration valve (37)~(39), pool aeration valve (40), sludge return pump (50), and sludge return valve (51); The signal output terminal of the online pH meter (9) is connected to the pH signal input terminal (54) of the data processor (52); the signal output terminals of the online DO meters (41)~(43) are connected to the DO signal input terminal (55) of the data processor (52); the data processor (52) is provided with a parameter setting and display terminal (56); the signal output terminal (57) of the data processor is connected to the signal input terminal (58) of the process controller, and the signal output terminal (59) of the process controller is connected to the first concentration water distribution pump (10), the first concentration water distribution valve (11), the second concentration water distribution pump (12), and the second concentration water distribution valve (13) respectively through control signal transmission lines. The alkali dosing pump (14), the alkali dosing valve (15), the A1 tank inlet pump (18), the A1 tank inlet valve (19), the A2 tank inlet pump (21), the A2 tank inlet valve (22), the A3 tank inlet pump (23), the A3 tank inlet valve (24), the A4 tank inlet pump (26), the A4 tank inlet valve (27), the blower (28), the main aeration valve (30), the O1 tank aeration valves (31)~(33), the O2 tank aeration valves (34)~(36), the O3 tank aeration valves (37)~(39), the O4 tank aeration valve (40), the sludge return pump (50), and the sludge return valve (51) are connected together; The wastewater deep denitrification method includes the following steps: Step (1) involves the preparation of the feed water into the segmented feed A / O reactor (5): ① Draw water of the first concentration into the first concentration water tank (1), and draw water of the second concentration into the second concentration water tank (2); ② The first concentration water distribution pump (10) and the second concentration water distribution pump (12) draw water from the first concentration water tank (1) and the second concentration water tank (2) respectively, and mix the first concentration water and the second concentration water into the mixing water tank (3) in proportion through the first concentration water distribution valve (11), the second concentration water distribution valve (13) and the mixing water tank distribution pipe (16); ③ The proportion λ1 of the second concentration water in the mixing tank (3) is determined by equation (1): (1) In the formula: C1 and C2 are the average COD concentrations of the first and second concentration waters calculated based on the measured COD concentrations of the first and second concentration waters at the wastewater treatment plant over the past 30 to 120 days, with the unit being mg / L; C N The ammonia nitrogen concentration is the average value calculated based on the measured data of the first concentration of ammonia nitrogen in the wastewater treatment plant over the past 30 to 120 days, and the unit is mg / L. For newly built wastewater treatment plants, if there is no measured data for 30 to 120 days, the average values ​​C1, C2, and C can be updated and calculated based on the measured data for the past 5 days, 15 days, 30 days, 60 days, and up to 120 days after the system has been running stably. N And the corresponding λ1 value is updated and calculated sequentially by equation (1); ④ The ratio of the first concentration water added to the mixing tank (3) is 1-λ1; ⑤ The alkali solution is dispensed from the alkali tank (4) into the mixing water tank (3) by the alkali pump (14). The pH value of the mixed water in the mixing water tank (3) is controlled to be not less than 7.0 by adjusting the alkali valve (15), while the ratio of the total alkalinity to the total nitrogen concentration of the mixed water is greater than 4. The total alkalinity is expressed as CaCO3. ⑥ After the system is running normally and stably, update the calculations of C1, C2, and C every 10 to 120 days. N The value is determined, and the new λ1 value is calculated using equation (1); Step (2): Start-up of the segmented influent A / O reactor (5): ① The activated sludge with nitrification and denitrification functions is fed into the segmented influent A / O reactor (5) so that the average sludge concentration in the segmented influent A / O reactor (5) is 4200mg / L~4500mg / L; ② Water is continuously fed into the first end of the A pool of each section of the segmented A / O reactor (5). The A1 pool is fed with the first concentration water in the first concentration water tank (1), the A2 and A3 pools are fed with the mixed water in the mixed water tank (3), and the A4 pool is fed with the second concentration water in the second concentration water tank (2). ③ Control the first three sections to have equal water intake, that is, the water intake Q1 of the first concentration water in pool A1 is equal to the water intake Q2 and Q3 of the mixed water in pools A2 to A3. The water intake Q4 of the second concentration water in pool A4 is determined according to its proportion λ2 to the water intake Q3 of the mixed water in pool A3, that is, Q4=λ2·Q3. ④ The proportion λ2 of Q4 to Q3 is determined by equation (2): (2) In the formula: C N The value of C2 is the same as in equation (1); ⑤ In accordance with the above water intake method, control the total nitrogen load of the water intake of the segmented water intake A / O reactor (5) to gradually increase from small, and control the dissolved oxygen DO in each O tank to be not less than 2 mg / L. The sludge return ratio of the system is 60%~75%. After the system stabilizes, it enters the next stage of stable operation. Step (3) During the stable operation phase of the system, the operation control mode of the segmented influent A / O reactor (5) is as follows: ① After the system is running stably, according to the water inlet distribution method described in step (1) and the water inlet method during system startup described in step (2), control the average sludge concentration in the segmented water inlet A / O reactor (5) to be 4200mg / L~4500mg / L, and the sludge return ratio of the system to be 60%~75%, and run continuously. For typical corn starch wastewater with a total nitrogen concentration of 400 mg / L to 480 mg / L in the second concentration water, the total hydraulic retention time of the segmented influent A / O reactor (5) is 30 h to 31 h. ② During system operation, the dissolved oxygen concentration in the end compartments of O1 to O3 is controlled at 3.0 mg / L to 3.5 mg / L. At the same time, the nitrate nitrogen concentration and COD concentration of the mixed liquor at the end of A4 tank in the segmented influent A / O reactor (5) are monitored 1 to 2 times a day. When the nitrate nitrogen concentration in the end-of-A4 pool is found to be greater than 4 mg / L, the influent flow rate Q4 of the second concentration water in the A4 pool is appropriately increased. The increase in Q4 is based on the nitrate nitrogen concentration in the end-of-A4 pool being less than or equal to 4 mg / L. When the COD concentration in the end-of-A4 pool is found to be greater than 115 mg / L, the influent flow rate Q4 is appropriately decreased. The decrease in Q4 is based on the COD concentration in the end-of-A4 pool being less than 115 mg / L, while simultaneously satisfying the nitrate nitrogen concentration being less than or equal to 4 mg / L.

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