Short-cut nitrification continuous flow control method and system based on free ammonia concentration analysis

Abstract

The application relates to a short-range nitrification continuous flow control method and system based on free ammonia concentration analysis, wherein the free ammonia concentration of influent of an n# short-range nitrification reactor at a first reference moment is denoted as FA1; the free ammonia concentration of influent of the n# short-range nitrification reactor at a second reference moment is denoted as FA0; the FA of the n# short-range nitrification reactor meeting [FA0, FA1] is a normal standard; if the FA of the n# short-range nitrification reactor is lower than the normal standard, the system aeration amount is gradually reduced until the FA of the n# short-range nitrification reactor meets the normal standard; if the FA of the n# short-range nitrification reactor is higher than the normal standard, the system aeration amount is gradually increased. The application can maintain a high conversion rate of ammonia nitrogen in treated wastewater, significantly improve the operation stability of a short-range nitrification denitrification continuous flow reactor, gradually eliminate nitrite oxidizing bacteria in microorganisms from the bacterial population, and obtain a high nitrite accumulation rate.

Description

Technical Field

[0001] This invention relates to the field of industrial nitrogen-containing wastewater treatment technology, specifically to a method for achieving stable continuous flow short-path nitrification-denitrification denitrification based on real-time monitoring of multiple parameters and control of aeration rate based on the influent free ammonia concentration of the final short-path nitrification reactor. Background Technology

[0002] Compared to traditional biological nitrogen removal processes, short-cut nitrification-denitrification technology can save oxygen supply, reduce carbon source demand by 40%, significantly shorten reaction time, and reduce sludge production in actual operation. The key to this technology lies in enriching ammonia-oxidizing bacteria (AOB) and eliminating nitrite-oxidizing bacteria (NOB), thereby reducing nitrite nitrogen (NO) in the effluent. 2- -N) and nitrite nitrogen and nitrate nitrogen (NO) 3- The ratio of the sum of -N reaches its highest value, indicating a stable and high nitrite accumulation rate.

[0003] In sequencing batch reactors (SBRs), a high nitrite accumulation rate can be easily achieved by stably controlling conditions such as temperature, pH, dissolved oxygen (DO), sludge age, and inhibitors during operation, as well as by identifying real-time control characteristic points for parameters such as pH, dissolved oxygen, and oxidation-reduction potential. The so-called characteristic point refers to the inflection point that appears on the real-time control parameter monitoring curve as ammonia nitrogen is essentially depleted during SBR operation.

[0004] With the advancement of technology, direct measurement of NH4 + The technology for determining NH4+ is becoming increasingly mature, among which the ion electrode method is used. + -N is more intuitive, and therefore it has been gradually applied to NH4. + Real-time monitoring of -N is underway. However, during nitrification, microorganisms actually utilize NH3 (free ammonia), not NH4. + -N, therefore, it is necessary to adjust the concentration of NH4+ based on the real-time pH, temperature, and NH4+ in the reactor. + The concentration of -N is calculated to determine the NH3 reaction process, allowing for timely adjustments to keep the nitration process at the ammonia oxidation stage and prevent it from progressing to the nitrite oxidation stage.

[0005] In continuous flow reactors, researchers generally believe that real-time parameter control can only play an auxiliary role, making it difficult to achieve stable short-cut nitrification-denitrification. When dealing with large flow rates, continuous flow reactors require less space, are easier to manage, and are more valuable for production applications. However, there are few reports of large-scale applications of short-cut nitrification-denitrification, making research on this technology in continuous flow reactors essential. Summary of the Invention

[0006] The present invention aims to address the above-mentioned problems by proposing a short-range nitrification continuous flow control method and system based on free ammonia concentration analysis.

[0007] The technical solution of this invention is as follows:

[0008] (i) This invention proposes a short-range nitrification continuous flow control method based on free ammonia concentration analysis.

[0009] A short-range nitrification continuous flow control method based on free ammonia concentration analysis is as follows:

[0010] Let the last short-cut nitrification reactor be designated as n# short-cut nitrification reactor; 3≤n≤8;

[0011] The initial time when AUR drops to below 70% of the normal value and DO increases by 20%-30% is taken as the first reference time. The influent free ammonia concentration of the n# short-cut nitrification reactor at the first reference time is FA1.

[0012] The second reference time is defined as the moment when the pH value changes to 0, the DO rises to above 6.0 mg / L, and the AUR approaches 0. The free ammonia concentration in the influent of the n# short-cut nitrification reactor at the second reference time is denoted as FA0. The normal standard is defined as the FA of the n# short-cut nitrification reactor meeting the condition of [FA0, FA1].

[0013] If the aeration rate (FA) of the n# short-cut nitrification reactor is lower than the normal standard, then the aeration rate of the (n-1)#, (n-2)#, (n-3)#...1# short-cut nitrification reactors should be decreased sequentially until the FA of the n# short-cut nitrification reactor meets the normal standard; if the FA of the n# short-cut nitrification reactor is higher than the normal standard, then the aeration rate of the (n-1)#, (n-2)#, (n-3)#...1# short-cut nitrification reactors should be increased sequentially until the FA of the n# short-cut nitrification reactor meets the normal standard; the decrease / increase in the aeration rate of the short-cut nitrification reactor should not exceed 50%.

[0014] Preferably, if the FA of the n# short-cut nitrification reactor is lower than the normal standard, the aeration rate of the (n-1)# short-cut nitrification reactor is reduced. If the FA of the n# short-cut nitrification reactor is still lower than the normal standard when the reduction reaches 50%, the aeration rate of the (n-2)#, (n-3)#...1# short-cut nitrification reactors is reduced sequentially according to this standard until the FA of the n# short-cut nitrification reactor meets the normal standard.

[0015] Preferably, if the FA of the n# short-cut nitrification reactor is higher than the normal standard, the aeration rate of the (n-1)# short-cut nitrification reactor is increased. If the FA of the n# short-cut nitrification reactor is still higher than the normal standard when the increase reaches 50%, the aeration rate of the (n-2)#, (n-3)#...1# short-cut nitrification reactors is increased sequentially according to this standard until the FA of the n# short-cut nitrification reactor meets the normal standard.

[0016] The rate of decrease / increase of aeration rate in the short-path nitrification reactor is (10~20%) / (5~10 min).

[0017] The calculation process for the FA of the n# short-path nitration reactor is as follows:

[0018] FA=[1.21*(NH4 + -N)*10 pH ] / {e [6344 / (273+T)] +10 pH} (1)

[0019] In the formula: FA is the concentration of free ammonia in the influent, in mg / L; (NH4) + (-N) represents ammonia nitrogen concentration, mg / L; T represents temperature, °C.

[0020] The specific calculation process of AUR is as follows:

[0021] AUR=[(NH4 + -N)t0-(NH4) + -N)t1] / △t (2)

[0022] In the formula: AUR is the ammonia oxidation rate, mg / (L·min); (NH4) + -N) t0 is the ammonia nitrogen concentration at time t0, mg / L; (NH4) + -N) t1 is the ammonia nitrogen concentration at time t1, mg / L; Δt is the time elapsed from time t0 to t1, min.

[0023] It also includes controlling the FA of the n# short-cut nitrification reactor to meet normal standards by adjusting the suspended sludge concentration or supplementing ammonia-oxidizing bacteria; the suspended sludge concentration is adjusted by discharging or supplementing suspended sludge, and the amount of suspended sludge discharged or supplemented is calculated by ammonia nitrogen volumetric load.

[0024] (ii) This invention proposes a short-range nitrification continuous flow control system based on free ammonia concentration analysis.

[0025] A short-cut nitrification continuous flow control system based on free ammonia concentration analysis includes n short-cut nitrification reactors connected in series. Each short-cut nitrification reactor is equipped with an aeration disc at its bottom. The first short-cut nitrification reactor is connected to the inlet, and the last short-cut nitrification reactor is connected to the outlet. The system also includes a data acquisition system, comprising online water quality parameter monitoring electrodes located within each short-cut nitrification reactor, and a data processing terminal connected to each online water quality parameter monitoring electrode. Each aeration disc is connected to the data processing terminal via an air pump. The online water quality parameter monitoring electrodes include a first sensor for monitoring dissolved oxygen (DO), a second sensor for monitoring pH, a third sensor for monitoring temperature, and a fourth sensor for monitoring ammonia nitrogen concentration.

[0026] An inlet pump and a buffer tank are sequentially installed between the inlet and the first short-cut nitrification reactor. The buffer tank is equipped with a stirrer. The inlet pump has an inlet flow rate of Q. The outlet flows back to the first short-cut nitrification reactor sequentially through a sedimentation tank and a reflux pump. The reflux pump has a reflux flow rate of 0.5Q.

[0027] The hydraulic retention time of the short-cut nitrification reactor is 0.5 to 1 hour.

[0028] The technical effects of this invention are as follows:

[0029] This invention enables the treatment of wastewater to maintain a high conversion rate of ammonia nitrogen, while significantly improving the operational stability of short-cut nitrification-denitrification continuous flow reactors, and gradually eliminating nitrite-oxidizing bacteria from the microbial community, thereby achieving a higher nitrite accumulation rate. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of a short-range nitrification continuous flow control system based on free ammonia concentration analysis.

[0031] Figure 2 This is a reaction flow diagram for short-path nitration continuous flow based on real-time analysis of free ammonia concentration.

[0032] Figure 3 A diagram showing the determination of the boundary values ​​for the normal standard.

[0033] Figure 4 This is a diagram illustrating the adjustment scheme for specific application scenario 1.

[0034] Figure 5 This is a diagram illustrating the adjustment scheme for specific application scenario 2.

[0035] Figure reference numerals: 1. Short-cut nitrification reactor; 6. Buffer tank; 7. Agitator; 8. Sedimentation tank; 9. Inlet pump; 10. Air pump; 11. Return pump; 12. Online water quality parameter monitoring electrode; 17. Data processing terminal. Detailed Implementation

[0036] Example 1

[0037] A short-cut nitrification continuous flow control system based on free ammonia concentration analysis includes n short-cut nitrification reactors 1 connected in series. Each short-cut nitrification reactor 1 is equipped with an aeration disc at its bottom. The first short-cut nitrification reactor is connected to the inlet, and the last short-cut nitrification reactor is connected to the outlet. The system also includes a data acquisition system, which includes online water quality parameter monitoring electrodes 12 located in each short-cut nitrification reactor 1, and a data processing terminal 17 connected to each online water quality parameter monitoring electrode 12. Each aeration disc is connected to the data processing terminal 17 via an air pump 10. The online water quality parameter monitoring electrodes 12 include a first sensor for monitoring dissolved oxygen (DO), a second sensor for monitoring pH, a third sensor for monitoring temperature, and a fourth sensor for monitoring ammonia nitrogen concentration.

[0038] The specific implementation process of this embodiment is as follows:

[0039] Let the last short-cut nitrification reactor be designated as n# short-cut nitrification reactor; 3≤n≤8;

[0040] The initial time when AUR drops to below 70% of the normal value and DO increases by 20%-30% is taken as the first reference time. The influent free ammonia concentration of the n# short-cut nitrification reactor at the first reference time is FA1.

[0041] The second reference time is defined as the moment when the pH value changes to 0, the DO rises to above 6.0 mg / L, and the AUR approaches 0. The free ammonia concentration in the influent of the n# short-cut nitrification reactor at the second reference time is denoted as FA0. The normal standard is defined as the FA of the n# short-cut nitrification reactor meeting the condition of [FA0, FA1].

[0042] If the aeration rate (FA) of the n# short-cut nitrification reactor is lower than the normal standard, then the aeration rate of the (n-1)#, (n-2)#, (n-3)#...1# short-cut nitrification reactors should be decreased sequentially until the FA of the n# short-cut nitrification reactor meets the normal standard; if the FA of the n# short-cut nitrification reactor is higher than the normal standard, then the aeration rate of the (n-1)#, (n-2)#, (n-3)#...1# short-cut nitrification reactors should be increased sequentially until the FA of the n# short-cut nitrification reactor meets the normal standard; the decrease / increase in the aeration rate of the short-cut nitrification reactor should not exceed 50%.

[0043] Example 2

[0044] Based on Example 1, the method further includes an inlet pump 9 and a buffer tank 6 sequentially connected between the inlet and the first short-cut nitrification reactor. The buffer tank 6 contains a stirrer 7, and the inlet flow rate of the inlet pump 9 is Q. The outlet water flows back to the first short-cut nitrification reactor sequentially through a sedimentation tank 8 and a reflux pump 11. The reflux flow rate of the reflux pump 11 is 0.5Q. The hydraulic retention time of the short-cut nitrification reactor 1 is 0.5~1 hour.

[0045] Example 3

[0046] Based on Example 2, it also includes,

[0047] If the FA of the n# short-cut nitrification reactor is lower than the normal standard, then reduce the aeration rate of the (n-1)# short-cut nitrification reactor. If the FA of the n# short-cut nitrification reactor is still lower than the normal standard when the reduction reaches 50%, then reduce the aeration rate of the (n-2)#, (n-3)#...1# short-cut nitrification reactors in sequence according to this standard until the FA of the n# short-cut nitrification reactor meets the normal standard.

[0048] If the FA of the n# short-cut nitrification reactor is higher than the normal standard, then increase the aeration rate of the (n-1)# short-cut nitrification reactor. If the FA of the n# short-cut nitrification reactor is still higher than the normal standard when the increase reaches 50%, then increase the aeration rate of the (n-2)#, (n-3)#...1# short-cut nitrification reactors in sequence according to this standard until the FA of the n# short-cut nitrification reactor meets the normal standard.

[0049] The rate of decrease / increase of aeration rate in the short-path nitrification reactor 1 is (10~20%) / (5~10min).

[0050] Example 4

[0051] Based on Example 3, it also includes,

[0052] The calculation process for the FA of the n# short-path nitration reactor is as follows:

[0053] FA=[1.21*(NH4 + -N)*10 pH ] / {e [6344 / (273+T)] +10 pH} (1)

[0054] The specific calculation process of AUR is as follows:

[0055] AUR=[(NH4 + -N)t0-(NH4) + -N)t1] / △t (2).

[0056] Example 5

[0057] Based on Example 4, the method further includes adjusting the suspended sludge concentration or supplementing ammonia-oxidizing bacteria to control the FA of the n# short-cut nitrification reactor to meet the normal standard; adjusting the suspended sludge concentration is achieved by discharging or supplementing suspended sludge, and the amount of suspended sludge discharged or supplemented is calculated by ammonia nitrogen volumetric load.

[0058] Specific application examples

[0059] A method for controlling continuous flow short-path nitrification based on free ammonia concentration analysis is presented below, taking five short-path nitrification reactors as an example.

[0060] Step 1: Obtain the normal standard limit values;

[0061] Stop the water intake and monitor the ammonia nitrogen concentration (NH4) in the No. 5 short-cut nitrification reactor. + -N), pH value, temperature and DO;

[0062] When the DO in the No. 5 short-cut nitrification reactor rises significantly by 20%-30%, and at the same time the AUR drops below 70% of the normal value, this moment is the first reference moment. Figure 3 It can be seen that the first reference time is t=40min; the corresponding FA1=1.5mg / L is calculated by formula (1);

[0063] The second reference time is when the pH value in the No. 5 short-cut nitrification reactor stabilizes and no longer decreases (change value is 0), while the DO rises above 6.0 mg / L and the AUR approaches 0. Figure 3 It can be seen that when the second reference time is t=100min, the corresponding FA0=0.5mg / L can be calculated by formula (1);

[0064] The normal standard is [0.5 mg / L, 1.5 mg / L].

[0065] Step 2: Adjust the FA of the No. 5 short-cut nitrification reactor to the normal standard, so that the FA of the No. n short-cut nitrification reactor meets the condition [FA0, FA1]; the specific process is as follows:

[0066] Specific application scenario 1: Due to fluctuations in the influent water quality, the (NH4+) in the No. 5 short-cut nitrification reactor... + -N) decreased to around 4-5 mg / L, correspondingly FA decreased to below 0.5 mg / L, therefore it needs to be adjusted to the normal standard: gradually adjust the aeration rate of the No. 4 short-cut nitrification reactor at a rate of -10% / 5 min; if the normal standard is not reached after 5 min, continue adjusting; if Figure 4As shown, when the aeration rate of the No. 4 short-cut nitrification reactor was reduced to 40%, i.e., at t=70min, the aeration rate of the No. 4 short-cut nitrification reactor was adjusted to 40%. At t=75min, the FA of the No. 4 short-cut nitrification reactor increased to 0.5mg / L. After adjusting to the normal standard, it was put into normal operation.

[0067] Specific application scenario 2: Due to fluctuations in the influent water quality, the (NH4+) in the No. 5 short-cut nitrification reactor... + -N) rose to around 13-17 mg / L, and the corresponding FA rose to above 1.5 mg / L, therefore it needs to be adjusted to the normal standard: gradually adjust the aeration rate of the No. 4 short-cut nitrification reactor at a rate of 10% / 5 min. If the normal standard is not reached after 5 min, continue to adjust; that is, at t=35 min, increase the aeration rate of the No. 4 short-cut nitrification reactor by 10%, at t=40 min, increase the aeration rate of the No. 4 short-cut nitrification reactor by 20%, until at t=55 min, the aeration rate of the No. 4 short-cut nitrification reactor is reduced to the normal standard. When the aeration rate of the reactor was increased to 50%, the FA in the No. 5 short-cut nitrification reactor was still above 1.5 mg / L at t=60 min. Therefore, the aeration rate of the No. 3 short-cut nitrification reactor was further adjusted by increasing the aeration rate of the No. 3 short-cut nitrification reactor by 10% until t=75 min. After increasing the aeration rate of the No. 3 short-cut nitrification reactor to 40%, 5 min later at t=80 min, the FA in the No. 5 short-cut nitrification reactor dropped below 1.5 mg / L. After adjusting to the normal standard, it was put into normal operation.

Claims

1. A short-range nitrification continuous flow control method based on free ammonia concentration analysis, characterized in that, The method is as follows: It includes several short-cut nitrification reactors connected in series, and the last short-cut nitrification reactor is denoted as n# short-cut nitrification reactor; 3≤n≤8; When the influent is stopped, the first reference time is the initial moment when the ammonia oxidation rate (AUR) of the n# short-cut nitrification reactor drops to below 70% of the normal value and the DO increases by 20%-30%. The influent free ammonia concentration of the n# short-cut nitrification reactor at the first reference time is denoted as FA1. The second reference time is defined as the moment when the pH change of the n# short-cut nitrification reactor is 0, the DO rises to above 6.0 mg / L and the AUR approaches 0. The influent free ammonia concentration of the n# short-cut nitrification reactor at the second reference time is denoted as FA0. The normal standard is defined as the FA of the n# short-cut nitrification reactor satisfying [FA0,FA1]. If the influent free ammonia concentration (FA) of the n# short-cut nitrification reactor is lower than the normal standard, then the aeration rate of the (n-1)#, (n-2)#, (n-3)#...1# short-cut nitrification reactors should be decreased sequentially until the FA of the n# short-cut nitrification reactor meets the normal standard; if the FA of the n# short-cut nitrification reactor is higher than the normal standard, then the aeration rate of the (n-1)#, (n-2)#, (n-3)#...1# short-cut nitrification reactors should be increased sequentially until the FA of the n# short-cut nitrification reactor meets the normal standard; the decrease / increase in the aeration rate of the short-cut nitrification reactor should not exceed 50%.

2. The short-range nitrification continuous flow control method based on free ammonia concentration analysis according to claim 1, characterized in that, If the FA of the n# short-cut nitrification reactor is lower than the normal standard, then reduce the aeration rate of the (n-1)# short-cut nitrification reactor. If the FA of the n# short-cut nitrification reactor is still lower than the normal standard when the reduction reaches 50%, then reduce the aeration rate of the (n-2)#, (n-3)#...1# short-cut nitrification reactors in sequence according to this standard until the FA of the n# short-cut nitrification reactor meets the normal standard.

3. The short-range nitrification continuous flow control method based on free ammonia concentration analysis according to claim 1, characterized in that, If the FA of the n# short-cut nitrification reactor is higher than the normal standard, then increase the aeration rate of the (n-1)# short-cut nitrification reactor. If the FA of the n# short-cut nitrification reactor is still higher than the normal standard when the increase reaches 50%, then increase the aeration rate of the (n-2)#, (n-3)#...1# short-cut nitrification reactors in sequence according to this standard until the FA of the n# short-cut nitrification reactor meets the normal standard.

4. The short-range nitrification continuous flow control method based on free ammonia concentration analysis according to claim 1, characterized in that, The rate of decrease / increase of aeration in the short-path nitrification reactor (1) is (10~20%) / (5~10min).

5. The short-range nitrification continuous flow control method based on free ammonia concentration analysis according to claim 1, characterized in that: The calculation process for the FA of the n# short-path nitrification reactor is as follows: FA=[1.21×(NH4 + (N)×10 pH ] / {And [6344 / (273+T)] +10 pH } (1) In the formula: FA is the concentration of free ammonia in the influent, in mg / L; (NH4) + (-N) represents ammonia nitrogen concentration, mg / L; T represents temperature, °C.

6. The short-range nitrification continuous flow control method based on free ammonia concentration analysis according to claim 1, characterized in that: The specific calculation process for AUR is as follows: AUR=[(NH4 + -N)t0-(NH4 + -N)t1] / △t (2) In the formula: AUR is the ammonia oxidation rate, mg / (L·min); (NH4) + -N) t0 is the ammonia nitrogen concentration at time t0, mg / L; (NH4) + -N) t1 is the ammonia nitrogen concentration at time t1, mg / L; Δt is the time elapsed from time t0 to t1, min.

7. The short-range nitrification continuous flow control method based on free ammonia concentration analysis according to claim 1, characterized in that: It also includes controlling the FA of the n# short-cut nitrification reactor to meet normal standards by adjusting the suspended sludge concentration or supplementing ammonia-oxidizing bacteria; the suspended sludge concentration is adjusted by discharging or supplementing suspended sludge, and the amount of suspended sludge discharged or supplemented is calculated by ammonia nitrogen volumetric load.

8. A system for implementing the short-range nitrification continuous flow control method based on free ammonia concentration analysis as described in claim 1, characterized in that, The system includes n short-cut nitrification reactors (1) connected in series. Each short-cut nitrification reactor (1) is equipped with an aeration disc at its bottom. The first short-cut nitrification reactor is connected to the inlet, and the last short-cut nitrification reactor is connected to the outlet. The system also includes a data acquisition system, which includes an online water quality parameter monitoring electrode (12) located in each short-cut nitrification reactor (1) and a data processing terminal (17) connected to each online water quality parameter monitoring electrode (12). The aeration discs are all connected to the data processing terminal (17) via an air pump (10). The online water quality parameter monitoring electrode (12) includes a first sensor for monitoring DO, a second sensor for monitoring pH, a third sensor for monitoring temperature, and a fourth sensor for monitoring ammonia nitrogen concentration.

9. The system according to claim 8, characterized in that, A water inlet pump (9) and a buffer tank (6) are sequentially arranged between the water inlet and the first short-cut nitrification reactor. A stirrer (7) is installed in the buffer tank (6). The water inlet flow rate of the water inlet pump (9) is Q. The water outlet flows back to the first short-cut nitrification reactor sequentially through a sedimentation tank (8) and a reflux pump (11). The reflux flow rate of the reflux pump (11) is 0.5Q.

10. The system according to claim 9, characterized in that, The hydraulic retention time of the short-path nitrification reactor (1) is 0.5 to 1 hour.

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