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

Abstract

The invention relates to a short-cut nitrification continuous flow control method and system based on free ammonia concentration analysis. The method comprises the following steps: recording the inflow free ammonia concentration of an n # short-cut nitrification reactor at a first reference moment as FA1; recording the inflow free ammonia concentration of the n # short-cut nitrification reactor at the second reference moment as FA0; the condition that FA of the n # short-cut nitrification reactor meets [FA0, FA1] is taken as a normal standard; if the FA of the n # short-cut nitrification reactor is lower than the normal standard, gradually reducing the aeration rate of the system 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, the aeration rate of the system is gradually increased. According to the invention, high conversion rate of ammonia nitrogen in the treated sewage can be maintained, the operation stability of the short-cut nitrification and denitrification continuous flow reactor can be obviously improved, nitrite oxidizing bacteria in microorganisms can be gradually eliminated out of flora, and high nitrite accumulation rate can be obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial nitrogen-containing wastewater treatment, and specifically to a method for achieving stable continuous flow shortcut nitrification and denitrification by real-time monitoring of multiple parameters and controlling the aeration volume based on the free ammonia concentration of the influent of the final shortcut nitrification reactor. Background Art

[0002] Compared with traditional biological denitrification processes, short-range nitrification and 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 the realization of this technology is to enrich ammonia oxidizing bacteria (AOB) and eliminate nitrite oxidizing bacteria (NOB), so that the nitrite nitrogen (NO 2- -N) and nitrite nitrogen and nitrate nitrogen (NO 3- The ratio of the sum of the nitrite accumulation rate to the nitrite accumulation rate reached the highest value, indicating a stable and high nitrite accumulation rate.

[0003] In a sequencing batch reactor, high nitrite accumulation rates can be easily achieved by maintaining stable control of temperature, pH, dissolved oxygen (DO), sludge age, inhibitors, and other conditions during operation, as well as identifying the real-time control characteristic points for parameters such as pH, dissolved oxygen, and redox potential. These characteristic points are defined as the inflection points on the real-time control parameter monitoring curves that appear when ammonia nitrogen is essentially depleted during operation of the sequencing batch reactor.

[0004] With the advancement of technology, direct determination of NH4 + -N technology is becoming more and more mature, among which the ion electrode method is used to determine NH4 + -N is more intuitive and is therefore gradually applied to NH4 + -N is being monitored in real time. However, during the nitrification process, microorganisms actually utilize NH3 (free ammonia) rather than NH4 + -N, so it is necessary to adjust the pH value, temperature and NH4 in real time in the reactor. + -N concentration is calculated to determine the progress of nitrification reaction, so as to make timely adjustments so that the nitrification process stays in the ammonia oxidation stage instead of continuing to develop into the nitrite oxidation stage.

[0005] In continuous flow reactors, however, researchers generally believe that real-time parameter control in continuous flow reactors is only auxiliary, making it difficult to achieve stable short-term nitrification and denitrification in continuous flow reactors. In situations with large water volumes, continuous flow reactors occupy less space, are easier to manage, and have greater production application value. However, there are currently few reports on large-scale applications of short-term nitrification and denitrification, so it is very necessary to study short-term nitrification and denitrification in continuous flow reactors. Summary of the Invention

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

[0007] The technical solution of the present invention is: (1) The present invention proposes a short-range nitrification continuous flow control method based on free ammonia concentration analysis.

[0008] The short-range nitrification continuous flow control method based on free ammonia concentration analysis is as follows: The last short-cut nitrification reactor is recorded as n# short-cut nitrification reactor; 3≤n≤8; The initial moment when AUR drops below 70% of the normal value and DO increases by 20%-30% is taken as the first reference moment, and the influent free ammonia concentration of the n# short-cut nitrification reactor at the first reference moment is recorded as FA1; The moment when the pH value changes to 0, DO rises to above 6.0 mg / L and AUR approaches 0 is taken as the second reference moment, and the free ammonia concentration of the inlet water of the n# shortcut nitrification reactor at the second reference moment is recorded as FA0; the FA of the n# shortcut nitrification reactor meeting [FA0, FA1] is considered normal. If the FA of the n# short-cut nitrification reactor is lower than the normal standard, the aeration rate of the (n-1)#, (n-2)#, (n-3)#…1# short-cut nitrification reactor shall be reduced in sequence 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, the aeration rate of the (n-1)#, (n-2)#, (n-3)#…1# short-cut nitrification reactor shall be increased in sequence until the FA of the n# short-cut nitrification reactor meets the normal standard; the reduction / increase value of the aeration rate of the short-cut nitrification reactor shall not exceed 50%.

[0009] 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 value reaches 50%, the aeration rates of the (n-2)#, (n-3)#...1# short-cut nitrification reactors are reduced in sequence according to this standard until the FA of the n# short-cut nitrification reactor meets the normal standard.

[0010] 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 value reaches 50%, the aeration rates of the (n-2)#, (n-3)#...1# short-cut nitrification reactors are increased in sequence according to this standard until the FA of the n# short-cut nitrification reactor meets the normal standard.

[0011] The rate of decrease / increase of the aeration amount of the short-cut nitrification reactor is (10-20%) / (5-10 min).

[0012] The calculation process of FA of the n# short-range nitrification reactor is as follows: FA=[1.21*(NH4 + -N)*10 pH ] / {e [6344 / (273+T)] +10 pH} (1) Where: FA is the free ammonia concentration in the influent, in mg / L; (NH4 + -N) is the ammonia nitrogen concentration, mg / L; T is the temperature, °.

[0013] The specific calculation process of the AUR is as follows: AUR=[(NH4 + -N)t0-(NH4 + -N)t1] / △t (2) Where: 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; △t is the time from t0 to t1, min.

[0014] It also includes controlling the FA of the n# short-range nitrification reactor to meet normal standards by adjusting the suspended sludge concentration or supplementing ammonia oxidizing bacteria; 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 the ammonia nitrogen volumetric load.

[0015] (2) The present invention proposes a short-range nitrification continuous flow control system based on free ammonia concentration analysis.

[0016] A short-cut nitrification continuous flow control system based on free ammonia concentration analysis includes n short-cut nitrification reactors connected in series, each of which is provided with an aeration disk at the bottom, the first short-cut nitrification reactor being connected to the water inlet, and the last short-cut nitrification reactor being connected to the water outlet; and also includes a data acquisition system, the data acquisition system including water quality parameter online monitoring electrodes located in each short-cut nitrification reactor, and a data processing terminal connected to each water quality parameter online monitoring electrode, the aeration disks being connected to the data processing terminal via an air pump; wherein the water quality parameter online monitoring electrodes include 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.

[0017] A water inlet pump and a buffer tank are sequentially provided between the water inlet end and the first short-cut nitrification reactor, an agitator is provided in the buffer tank, and the water inlet volume of the water inlet pump is Q; the water outlet end sequentially flows back to the first short-cut nitrification reactor through a sedimentation tank and a reflux pump; the reflux volume of the reflux pump is 0.5Q.

[0018] The hydraulic retention time of the short-cut nitrification reactor is 0.5 to 1 h.

[0019] The technical effects of the present invention are: The present invention can maintain a high conversion rate of ammonia nitrogen in the treated sewage, while significantly improving the operating stability of the short-range nitrification and denitrification continuous flow reactor, so that nitrite oxidizing bacteria in the microorganisms are gradually eliminated from the bacterial community, and a higher nitrite accumulation rate is obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the structure of the short-range nitrification continuous flow control system based on free ammonia concentration analysis.

[0021] Figure 2 The figure shows the reaction flow diagram of the continuous flow of short-range nitrification based on real-time analysis of free ammonia concentration.

[0022] Figure 3 Determine the limit values of normal standards.

[0023] Figure 4 This is the adjustment plan diagram for specific application situation 1.

[0024] Figure 5 This is the adjustment plan diagram for specific application situation 2.

[0025] Figure numerals: 1. Short-range nitrification reactor; 6. Buffer tank; 7. Agitator; 8. Sedimentation tank; 9. Water inlet pump; 10. Air pump; 11. Reflux pump; 12. Water quality parameter online monitoring electrode; 17. Data processing terminal. DETAILED DESCRIPTION

[0026] Example 1 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 of which is provided with an aeration disk at the bottom, the first short-cut nitrification reactor being connected to the water inlet, and the last short-cut nitrification reactor being connected to the water outlet; and also includes a data acquisition system, the data acquisition system including 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 disks being connected to the data processing terminal 17 via an air pump 10; wherein 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.

[0027] The specific implementation process of this embodiment is as follows: The last short-cut nitrification reactor is recorded as n# short-cut nitrification reactor; 3≤n≤8; The initial moment when AUR drops below 70% of the normal value and DO increases by 20%-30% is taken as the first reference moment, and the influent free ammonia concentration of the n# short-cut nitrification reactor at the first reference moment is recorded as FA1; The moment when the pH value changes to 0, DO rises to above 6.0 mg / L and AUR approaches 0 is taken as the second reference moment, and the free ammonia concentration of the inlet water of the n# shortcut nitrification reactor at the second reference moment is recorded as FA0; the FA of the n# shortcut nitrification reactor meeting [FA0, FA1] is considered normal. If the FA of the n# short-cut nitrification reactor is lower than the normal standard, the aeration rate of the (n-1)#, (n-2)#, (n-3)#…1# short-cut nitrification reactor shall be reduced in sequence 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, the aeration rate of the (n-1)#, (n-2)#, (n-3)#…1# short-cut nitrification reactor shall be increased in sequence until the FA of the n# short-cut nitrification reactor meets the normal standard; the reduction / increase value of the aeration rate of the short-cut nitrification reactor shall not exceed 50%.

[0028] Example 2 Based on Example 1, the present invention further comprises: an inlet pump 9 and a buffer tank 6 are sequentially provided between the water inlet and the first short-cut nitrification reactor; the buffer tank 6 is provided with an agitator 7; the water inlet flow rate of the inlet pump 9 is Q; the water outlet is sequentially returned to the first short-cut nitrification reactor through a sedimentation tank 8 and a reflux pump 11; the reflux flow rate of the reflux pump 11 is 0.5Q; and the hydraulic retention time of the short-cut nitrification reactor 1 is 0.5-1 hour.

[0029] Example 3 On the basis of Example 2, it also includes: If the FA of the n# short-cut nitrification reactor is lower than the normal standard, 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 value reaches 50%, reduce the aeration rate of the (n-2)#, (n-3)#…1# short-cut nitrification reactors in this order 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, 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 value reaches 50%, the aeration rate of the (n-2)#, (n-3)#…1# short-cut nitrification reactor is increased in turn according to this standard until the FA of the n# short-cut nitrification reactor meets the normal standard; The rate of decrease / increase of the aeration amount of the short-cut nitrification reactor 1 is (10-20%) / (5-10 min).

[0030] Example 4 On the basis of Example 3, it also includes: The calculation process of FA of the n# short-range nitrification reactor is as follows: FA=[1.21*(NH4 + -N)*10 pH ] / {e [6344 / (273+T)] +10 pH} (1) The specific calculation process of the AUR is as follows: AUR=[(NH4 + -N)t0-(NH4 + -N)t1] / △t (2).

[0031] Example 5 On the basis of Example 4, it also includes controlling the FA of the n# short-range nitrification reactor to meet normal standards by adjusting the suspended sludge concentration or supplementing ammonia oxidizing bacteria; adjusting the suspended sludge concentration is achieved by discharging or supplementing the suspended sludge, and the amount of suspended sludge discharged or supplemented is calculated by the ammonia nitrogen volumetric load.

[0032] Specific application cases A method for controlling continuous flow of short-cut nitrification based on free ammonia concentration analysis is provided, taking five short-cut nitrification reactors 1 as an example, and the method is as follows.

[0033] Step 1: Obtain the limit value of normal standard; Stop water inlet and monitor the ammonia nitrogen concentration (NH4 + -N), pH, temperature and DO; When the DO in the 5# short-cut nitrification reactor increases by 20%-30% and a significant rise occurs, and at the same time the AUR decreases to below 70% of the normal value, this moment is the first reference moment. Figure 1 It can be seen that the first reference time is t=40min; the corresponding FA1=1.5mg / L is calculated by formula (1); The second reference time is when the pH value in the 5# short-cut nitrification reactor is stable and no longer decreases (the change value is 0), and the DO rises to above 6.0 mg / L and the AUR approaches 0. Figure 1 It can be seen that when the second reference time is t=100min, the corresponding FA0=0.5mg / L is calculated by formula (1); That is, the normal standard is [0.5 mg / L, 1.5 mg / L].

[0034] Step 2: Adjust the FA of the 5# short-cut nitrification reactor to the normal standard, that is, the FA of the n# short-cut nitrification reactor meets [FA0, FA1]. The specific process is: Specific application 1: Due to the fluctuation of water quality at the front end, the (NH4 + -N) is reduced to about 4-5mg / L, and the corresponding FA is reduced to below 0.5mg / L, so it is necessary to adjust to the normal standard: gradually adjust the aeration volume of the 4# short-range nitrification reactor at a rate of -10% / 5min. If it does not reach the normal standard after 5 minutes, continue to adjust; if Figure 4 As shown, until the aeration rate of the 4# shortcut nitrification reactor is reduced to 40%, that is, at t=70min, the aeration rate of the 4# shortcut nitrification reactor is adjusted to be reduced to 40%. At t=75min, the FA of the 4# shortcut nitrification reactor increases to 0.5mg / L, and it operates normally after being adjusted to the normal standard. Specific application 2: Due to the fluctuation of water quality at the front end, the (NH4 +-N) increased to about 13-17mg / L, and the corresponding FA increased to more than 1.5mg / L, so it was necessary to adjust to the normal standard: gradually adjust the aeration volume of the 4# short-cut nitrification reactor at a rate of 10% / 5min. If it did not reach the normal standard after 5min, continue to adjust; that is, at t=35min, increase the aeration volume of the 4# short-cut nitrification reactor by 10%, at t=40min, increase the aeration volume of the 4# short-cut nitrification reactor by 20%, until at t=55min, increase the aeration volume of the 4# short-cut nitrification reactor by 10%. The aeration rate of the reactor increased to 50%. At t=60min, the FA of the 5# short-cut nitrification reactor was still above 1.5mg / L. Therefore, the aeration rate of the 3# short-cut nitrification reactor was continued to be adjusted, that is, the aeration rate of the 3# short-cut nitrification reactor was increased by 10%. Until at t=75min, the aeration rate of the 3# short-cut nitrification reactor was increased to 40%. 5min later, at t=80min, the FA of the 5# short-cut nitrification reactor dropped to below 1.5mg / L. It was adjusted to the normal standard and operated normally.

Claims

1. A short-range nitrification continuous flow control method based on free ammonia concentration analysis, characterized in that: Here’s how: The last short-cut nitrification reactor is recorded as n# short-cut nitrification reactor; 3≤n≤8; The initial moment when AUR drops below 70% of the normal value and DO increases by 20%-30% is taken as the first reference moment, and the influent free ammonia concentration of the n# short-cut nitrification reactor at the first reference moment is recorded as FA1; The moment when the pH value changes to 0, DO rises to above 6.0 mg / L and AUR approaches 0 is taken as the second reference moment, and the free ammonia concentration of the inlet water of the n# shortcut nitrification reactor at the second reference moment is recorded as FA0; the FA of the n# shortcut nitrification reactor meeting [FA0, FA1] is considered normal. If the FA of the n# short-cut nitrification reactor is lower than the normal standard, the aeration rate of the (n-1)#, (n-2)#, (n-3)#…1# short-cut nitrification reactor shall be reduced in sequence 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, the aeration rate of the (n-1)#, (n-2)#, (n-3)#…1# short-cut nitrification reactor shall be increased in sequence until the FA of the n# short-cut nitrification reactor meets the normal standard; the reduction / increase value of the aeration rate of the short-cut nitrification reactor shall not exceed 50%.

2. The method for controlling the short-range nitrification continuous flow 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, the aeration rate of the (n-1)# short-cut nitrification reactor shall be reduced. If the FA of the n# short-cut nitrification reactor is still lower than the normal standard when the reduction value reaches 50%, the aeration rate of the (n-2)#, (n-3)#…1# short-cut nitrification reactor shall be reduced in turn according to this standard until the FA of the n# short-cut nitrification reactor meets the normal standard.

3. The method for controlling the short-range nitrification continuous flow 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, the aeration rate of the (n-1)# short-cut nitrification reactor shall be increased. If the FA of the n# short-cut nitrification reactor is still higher than the normal standard when the increase value reaches 50%, the aeration rate of the (n-2)#, (n-3)#…1# short-cut nitrification reactors shall be increased in turn according to this standard until the FA of the n# short-cut nitrification reactor meets the normal standard.

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

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

6. The method for controlling the continuous flow of short-range nitrification based on free ammonia concentration analysis according to claim 1, characterized in that: The specific calculation process of the AUR is as follows: AUR=[(NH4 + -N)t0-(NH4 + -N)t1] / △t(2) Where: 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; △t is the time from t0 to t1, min.

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

8. A system for implementing the short-range nitrification continuous flow control method based on free ammonia concentration analysis as claimed in claim 1, characterized in that: The invention comprises n serially connected short-cut nitrification reactors (1), each of which is provided with an aeration disk at the bottom, the first short-cut nitrification reactor being connected to the water inlet, and the last short-cut nitrification reactor being connected to the water outlet; and further comprises a data acquisition system, the data acquisition system comprising a water quality parameter online monitoring electrode (12) located in each short-cut nitrification reactor (1), and a data processing terminal (17) connected to each water quality parameter online monitoring electrode (12), the aeration disks being connected to the data processing terminal (17) via an air pump (10); wherein the water quality parameter online monitoring electrode (12) comprises a first sensor for monitoring DO, a second sensor for monitoring pH value, 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 provided between the water inlet end and the first short-cut nitrification reactor. A stirrer (7) is provided in the buffer tank (6). The water inlet volume of the water inlet pump (9) is Q. The water outlet flows back to the first short-cut nitrification reactor through a sedimentation tank (8) and a reflux pump (11) in sequence. The reflux volume 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-cut nitrification reactor (1) is 0.5-1 h.

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