A method and system for spneda control

Abstract

The present application relates to wastewater treatment technical field, disclose a kind of SPNEDA control method and system thereof, the method includes: step 1: anaerobic stage: wastewater is added to SPNEDA reactor, make liquid level reach preset position, then control SPNEDA reactor to operate in anaerobic mode, anaerobic 60min, denitrifying bacteria in SPNEDA reactor carry out the storage of carbon source, and SPNEDA reactor is heated;Step 2: aerobic stage: aerobic aeration is carried out in SPNEDA reactor, aeration 360min, ammonia oxidizing bacteria in SPNEDA reactor carry out autotrophic shortcut nitrification;Step 3: anoxic stage: after anoxic 210min, after 35min of precipitation, drainage is carried out, anaerobic ammonia oxidation bacteria carry out anaerobic ammonia oxidation reaction, and denitrifying bacteria carry out endogenous denitrification.The present application combines SPNA process with endogenous denitrification technology, and nitrogen removal can be realized without additional carbon source denitrification process, and the excessive growth of denitrifying bacteria and the competition of substrate of anaerobic ammonia oxidation bacteria can be effectively avoided, and the SPNEDA reactor of anaerobic ammonia oxidation can be started faster.

Description

Technical Field

[0001] This invention relates to the field of wastewater, and specifically to a SPNEDA control method and system. Background Technology

[0002] Denitrification, as a coupling method, has long been studied as a coupled process to further treat nitrogen in water. The denitrification process requires the use of organic carbon sources, which typically include three parts: internal carbon sources, raw water carbon sources, and external carbon sources. When using traditional nitrification-denitrification processes to treat low C / N wastewater, additional carbon sources need to be added during the denitrification stage due to insufficient organic carbon sources required for denitrification, resulting in costs associated with adding external carbon sources. Summary of the Invention

[0003] The present invention aims to provide a SPNEDA control method and system to solve the problem that current wastewater denitrification requires the addition of an additional carbon source, which results in high costs.

[0004] To achieve the above objectives, the present invention provides an SPNEDA control method and system, comprising:

[0005] Step 1: Anaerobic stage: Add wastewater to the SPNEDA reactor until the liquid level reaches the preset position, then control the SPNEDA reactor to operate in anaerobic mode for 60 minutes. During this anaerobic period, the denitrifying bacteria in the SPNEDA reactor store carbon sources and heat the reactor. 25 to 35 minutes before the end of the anaerobic stage, add NH2OH (hydroxylamine) at a concentration of 4 to 8 mg / L to the SPNEDA reactor.

[0006] Step 2: Aerobic stage: Aerobic aeration is carried out in the SPNEDA reactor for 360 minutes, and the ammonia-oxidizing bacteria in the SPNEDA reactor carry out autotrophic short-cut nitrification.

[0007] Step 3: Anoxic stage: After 210 min of anoxic conditions, sedimentation is carried out for 35 min, followed by drainage. Anaerobic ammonia oxidizing bacteria in the SPNEDA reactor carry out anaerobic ammonia oxidation reaction, while denitrifying bacteria carry out endogenous denitrification.

[0008] Preferably, in step 1, NH2OH at a concentration of 6 mg / L is added to the SPNEDA reactor 25 minutes before the end of the anaerobic stage.

[0009] Preferably, the dissolved oxygen content in the SPNEDA reactor at each stage is controlled to be less than 0.8 mg / L, and the pH value is 7.2-8.2.

[0010] Preferably, in step 2, the wastewater from the SPNEDA reactor is refluxed and stirred.

[0011] Preferably, the temperature of the SPNEDA reactor is maintained at 28–32°C in step 1.

[0012] Preferably, in step 2, the wastewater at the top of the SPNEDA reactor is returned to the bottom of the SPNEDA reactor via an external reflux method. This ensures sufficient contact between the wastewater and granular sludge in the SPNEDA reactor, increases the mass transfer process, eliminates internal hydraulic dead zones, and ensures good sludge flow and stable operation. Simultaneously, oxygen is supplied to the bottom of the SPNEDA reactor to control the dissolved oxygen level at the bottom of the reactor.

[0013] To achieve the above objectives, this solution also provides an SPNEDA system, including: a DO / pH probe, a constant temperature water tank, an aeration pump, and an inlet tank, an SPNEDA reactor, and an outlet tank connected in sequence. The constant temperature water tank and the SPNEDA reactor are connected by an interlayer between their inner and outer walls. The aeration pump is used to aerate the SPNEDA reactor, and the DO / pH probe is used to detect the dissolved oxygen and pH value of the wastewater in the SPNEDA reactor.

[0014] Preferably, the reactor also includes a return pump for returning wastewater from the top of the SPNEDA reactor to the bottom of the SPNEDA reactor. This ensures sufficient contact between the wastewater and granular sludge in the SPNEDA reactor, increases the mass transfer process, eliminates internal hydraulic dead zones, and maintains good sludge flowability and stable operation. Simultaneously, oxygen is delivered to the bottom of the SPNEDA reactor to control the dissolved oxygen level at the bottom.

[0015] Preferably, the reactor also includes an aeration disc located at the top of the SPNEDA reactor and connected to an aeration pump. The aeration disc increases dissolved oxygen in the water by releasing air (typically compressed air) into the water in the form of tiny bubbles, uniformly introducing air or oxygen into the water, thereby promoting oxygen dissolution, improving water quality, and promoting the growth of microorganisms and the degradation of organic matter.

[0016] SPNA (Simultaneous Nitrification-Anammox) refers to a process where simultaneous nitrification coupled with anammox occurs. First, ammonia nitrogen is converted to nitrite nitrogen by ammonia-oxidizing bacteria. Then, anammox converts both ammonia nitrogen and nitrite nitrogen into nitrogen gas and nitrate nitrogen. SPNEDA (Simultaneous Nitrification-Anammox-Denitrification) is an integrated short-cut nitrification-coupled anammox-denitrification endogenous denitrification process. This particular SPNEDA process combines SPNA with endogenous denitrification technology, allowing AOB (Anammox-Oxygen Absorption) to partially denitrify NH4 under low DO conditions. + -N is converted to NO 2- -N, then AnAOB uses NH4 + -N and NO2 - -N generates N2 and produces some NO3.- -N, finally DGAOs will remove the remaining NO in the system. 2- -N and NO 3- -N is denitrified to N2, and the entire process involves the removal of organic matter. This denitrification process fully utilizes the carbon source in the raw water, achieving nitrogen removal without the addition of an additional carbon source. It effectively avoids competition between denitrifying bacteria and anaerobic ammonia oxidizing bacteria. Due to the low rate of endogenous denitrification, the growth rate of denitrifying bacteria is also low, effectively preventing excessive growth of denitrifying bacteria and competition for substrates with anaerobic ammonia oxidizing bacteria. This allows for faster startup of the SPNEDA reactor for anaerobic ammonia oxidation. Specifically, in the anaerobic stage, the substrates for denitrifying bacteria are nitrite nitrogen and nitrate nitrogen, while the substrates for anaerobic ammonia oxidizing bacteria are nitrite nitrogen and ammonia nitrogen. Because the endogenous denitrification rate is low, anaerobic ammonia oxidizing bacteria preferentially utilize nitrite nitrogen, while the generated nitrate nitrogen provides substrate for endogenous denitrifying bacteria, achieving deep nitrogen removal. During the anaerobic stage, NH2OH is added to inhibit NOB activity, reducing the impact of NOB on AOB activity and restoring the system's nitrogen removal performance for long-term continuous wastewater treatment. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of an SPNEDA system according to an embodiment of the present invention. Detailed Implementation

[0018] The following detailed description illustrates the specific implementation method:

[0019] The reference numerals in the accompanying drawings include:

[0020] 1. Inlet tank; 2. Inlet pump; 3. Return pump; 4. SPNEDA reactor; 5. DO / pH probe; 6. Aeration pipe; 7. Constant temperature water tank; 8. Water bath circulation pump; 9. Aeration pump; 10. Heating rod.

[0021] Example:

[0022] Endogenous denitrification technology can remove nitrogen by fully utilizing the carbon source of the raw water and without adding additional carbon sources. For example, glycogen accumulating organisms (GAOs) consume glycogen (Gly) in the anaerobic stage and absorb external carbon sources into their bodies to form and store polyhydroxyalkanoates (PHAs). In the aerobic stage, they decompose PHAs to synthesize Gly. One type of GAO has denitrification capabilities and can decompose PHAs to synthesize Gly under anoxic conditions, using NO3- as a byproduct. - -N and NO2 --N acts as an electron acceptor for denitrification, thus achieving denitrification under conditions that fully utilize the carbon source of the raw water. This type of bacteria is named endogenous denitrifying glycogen accumulating organisms (DGAOs).

[0023] To develop a faster-starting SPNEDA reactor for anaerobic ammonium oxidation, this study combined the SPNA process with endogenous denitrification technology. Under low dissolved oxygen (DO) conditions, AOB (aerobic ammonium oxidizing bacteria) partially oxidized NH4+. + -N is converted to NO2 - -N, then AnAOB (anaerobic ammonia-oxidizing bacteria) utilizes NH4 + -N and NO2 - -N generates N2 and produces some NO. 3- -N, finally DGAOs (denitrifying bacteria) will remove the remaining NO in the system. 2- -N and NO 3- -N is denitrified to N2, and the entire process is accompanied by the removal of organic matter. In the anaerobic stage, the substrates of denitrifying bacteria are nitrite nitrogen and nitrate nitrogen, while the substrates of anaerobic ammonia oxidizing bacteria are nitrite nitrogen and ammonia nitrogen. Due to the low rate of endogenous denitrification, anaerobic ammonia oxidizing bacteria preferentially utilize nitrite nitrogen, while the nitrate nitrogen produced provides substrates for endogenous denitrifying bacteria, achieving the purpose of deep nitrogen removal. This can effectively avoid the overgrowth of denitrifying bacteria and competition for substrates with anaerobic ammonia oxidizing bacteria.

[0024] A SPNEDA system control method includes the following steps:

[0025] Step 1: Anaerobic stage: Add wastewater to SPNEDA reactor 4 until the liquid level reaches the preset position, then control SPNEDA reactor 4 to operate in anaerobic mode for 60 minutes. During this anaerobic period, the denitrifying bacteria in SPNEDA reactor 4 store carbon sources and heat SPNEDA reactor 4.

[0026] In this step, denitrifying bacteria consume glycogen (Gly) under anaerobic conditions and absorb external carbon sources into their bodies to form polyhydroxyalkanoates (PHAs) and store them.

[0027] In this step, NH2OH at a concentration of 4-8 mg / L is added to SPNEDA reactor 4 25-35 minutes before the end of the anaerobic stage. Preferably, NH2OH at a concentration of 6 mg / L is added to SPNEDA reactor 4 25 minutes before the end of the anaerobic stage. The SPNEDA process, which combines SPNA technology with endogenous denitrification technology, suffers from the inherent application bottleneck of the SPNA process: the increase in NOB makes short-cut nitrification difficult to maintain. In the SPNEDA system, when NOB activity increases, it not only affects the activities of AOB and AnAOB, but also... 2- Competition from nitrogen (-N) has an adverse effect on diuretic oxygen (DGAOs). This solution involves adding NH₂OH during the anaerobic stage to inhibit NOB activity, thereby reducing the impact of NOB on AOB activity and restoring the system's denitrification performance for long-term, continuous wastewater treatment.

[0028] The specific evidence demonstrating that NH2OH inhibits NOB activity is as follows:

[0029] This short-term pilot experiment consisted of 6 parallel groups:

[0030] Experiments numbered 1, 2, and 3 were conducted under anaerobic conditions; experiments numbered 4, 5, and 6 were conducted under aerobic conditions. Experiments numbered 1, 2, and 3 were conducted under anaerobic conditions.

[0031] In the small-scale experiments of groups 1, 2, and 3, as the concentration of NH2OH increased, the NO3 in the effluent at the end of the aerobic stage... - The NO concentration gradually decreased, reaching 15.6, 13.2, and 11.66 mg / L, respectively. However, with the increase of the added NH2OH concentration, the NO concentration in the system effluent increased. 3- The decreasing trend of -N also indicates that the activity of NOB has been effectively inhibited.

[0032] At aerobic dosing points 4, 5, and 6, the effluent NO... 3- -N concentrations also decreased significantly, dropping to 16.5, 12.98, and 11.60 mg / L, respectively. After adding NH₂OH, the effluent NH₄⁺ concentration decreased. +The concentration of -N did not decrease significantly. After short-term addition of NH2OH, the denitrification performance of the system did not change significantly. In the short term, NH2OH treatment will have an adverse effect on AOB and hinder the nitrification process of the system.

[0033] Regardless of whether NH2OH was added at the aerobic or anaerobic site, the inhibition of NOB activity was greater than that of AOB. Based on the combined results of the two experiments under both anaerobic and aerobic conditions, anaerobic addition was the optimal condition, with the optimal NH2OH concentration being 6 mg / L and the addition time being 25 min.

[0034] Step 2: Aerobic stage: Aerobic aeration is carried out in SPNEDA reactor 4 for 360 minutes, and the ammonia-oxidizing bacteria in SPNEDA reactor 4 carry out autotrophic short-cut nitrification.

[0035] In this step, denitrifying bacteria decompose PHAs to synthesize Gly during the aerobic stage, while ammonia-oxidizing bacteria perform autotrophic short-cut nitrification.

[0036] In this step, the DO value in SPNEDA reactor 4 is maintained at 0.8 mg / L.

[0037] In this step, the wastewater in SPNEDA reactor 4 is recirculated and stirred to ensure sufficient contact between the wastewater and the granular sludge in SPNEDA reactor 4. Specifically, an external recirculation method is used to return the wastewater from the top of SPNEDA reactor 46 to the bottom of SPNEDA reactor 46. This ensures sufficient contact between the wastewater and granular sludge in SPNEDA reactor 4, increases the mass transfer process, eliminates internal hydraulic dead zones, and ensures good sludge flowability and stable operation. Simultaneously, oxygen is supplied to the bottom of SPNEDA reactor 4 to control the dissolved oxygen level at the bottom of SPNEDA reactor 4. A peristaltic pump is used in this scheme for wastewater recirculation.

[0038] Step 3: Anoxic stage: After settling for 35 minutes, drain the water. Anaerobic ammonia oxidizing bacteria carry out anaerobic ammonia oxidation reaction, and denitrifying bacteria carry out endogenous denitrification. After settling is complete, drain the water.

[0039] In this step, denitrifying bacteria decompose PHAs to synthesize Gly under anaerobic conditions, using NO3-. - -N and NO2 - -N acts as an electron acceptor for denitrification, thus achieving denitrification while fully utilizing the carbon source of the raw water. Because the endogenous denitrification rate is low, the growth rate of denitrifying bacteria is also low, effectively preventing excessive growth of denitrifying bacteria from competing with anaerobic ammonia-oxidizing bacteria for substrates.

[0040] In this step, the drainage ratio is 50%. Reasonable drainage avoids water flow that is too fast or too slow, maintains stable system operation, and avoids poor treatment effect due to overload.

[0041] The dissolved oxygen (DO), pH, and temperature in the system all affect the effectiveness of hydroxylamine. In this scheme, the temperature of SPNEDA reactor 4 is maintained at 28–32°C, preferably 30°C, at each stage. Specifically, water bath heating or other methods can be used to maintain the temperature inside SPNEDA reactor 4. Dissolved oxygen in SPNEDA reactor 4 is monitored and controlled below 0.8 mg / L, and the pH value is between 7.2 and 8.2 at each stage.

[0042] This scheme combines the SPNA process with endogenous denitrification technology. SPNEDA reactor 4 operates in AOA mode (anaerobic-aerobic-anoxic). In the anaerobic stage, DGAOs absorb and store external carbon sources; in the aerobic stage, GAOs decompose PHAs to synthesize Gly; and in the anoxic stage, during the decomposition of PHAs to synthesize Gly, NO3- is used as the active ingredient. - -N and NO2 - -N acts as an electron acceptor for denitrification, thus achieving denitrification under conditions that fully utilize the carbon source of the raw water; under low DO conditions, AOB will partially convert NH4+. + -N is converted to NO 2- -N, then AnAOB uses NH4 + -N and NO 2- -N generates N2 and produces some NO. 3- -N, finally DGAOs will remove the remaining NO in the system. 2- -N and NO 3- -N is denitrified to N2, and the entire process is accompanied by the removal of organic matter. This denitrification process removes nitrogen without the addition of an additional carbon source. Furthermore, due to the low rate of endogenous denitrification, the growth rate of denitrifying bacteria is also low, effectively preventing excessive growth of denitrifying bacteria from competing with anaerobic ammonia oxidizing bacteria for substrates. This allows for faster startup of the SPNEDA reactor 4 for anaerobic ammonia oxidation. During the anaerobic stage, NH2OH is added to inhibit NOB activity, reducing the impact of NOB on AOB activity and restoring the system's denitrification performance, enabling long-term continuous wastewater treatment.

[0043] like Figure 1 As shown, this solution also provides an SPNEDA system for implementing the above method, specifically including a DO / pH probe 5, a constant temperature water tank 7, an aeration pump 9, and an inlet tank 1, an SPNEDA reactor 4, and an outlet tank connected in sequence. The constant temperature water tank 7 and the SPNEDA reactor 4 are connected by a sandwich structure between their inner and outer walls. The aeration pump 9 is used to aerate the SPNEDA reactor 4, and the DO / pH probe 5 is used to detect the dissolved oxygen and pH value of the wastewater in the SPNEDA reactor 4. In this embodiment, the DO / pH probe 5 is specifically a WTW-DO / pH probe, specifically using a WTW Multi340i to detect and record the pH, temperature, and DO value inside the SPNEDA reactor.

[0044] In this embodiment, the SPNEDA reactor used has a cylindrical upper sleeve and a conical lower structure. The inner diameter of the cylindrical part of the SPNEDA reactor is 100mm and the height is 400mm. The overflow weir at the reactor outlet is filled with polyurethane sponge packing 40mm-60mm below it, and an aeration head is set in the hollow part. The height of the lower conical part of the SPNEDA reactor is 60mm, and the total volume of the SPNEDA reactor is 3.3L.

[0045] The constant temperature water tank 7 is equipped with a heating rod 10, which is used to heat the constant temperature water tank and maintain the temperature of the water in the constant temperature water tank, thereby keeping the temperature of the mixed liquid in the SPNEDA reactor at 30±2℃.

[0046] It also includes a return pump 3, which is used to return wastewater from the top of SPNEDA reactor 4 to the bottom of SPNEDA reactor 4. This ensures sufficient contact between the wastewater and granular sludge in SPNEDA reactor 4, increases the mass transfer process, eliminates internal hydraulic dead zones, and maintains good sludge flowability and stable operation. Simultaneously, it delivers oxygen to the bottom of SPNEDA reactor 4 to control the dissolved oxygen level there. The discharge port of the outlet pipe connected to the return pump 3 is inclined on SPNEDA reactor 4, and the inclination direction of the discharge port is adjustable. The inlet of the inlet pipe connected to the return pump 3 is inclined downwards on SPNEDA reactor 4.

[0047] It also includes an aeration disc and aeration pipe 6. The aeration disc is located inside the SPNEDA reactor 4 and is connected to the aeration pump 9 via the aeration pipe 6. The aeration disc increases the dissolved oxygen in the water by releasing air (usually compressed air) into the water in the form of fine bubbles, uniformly introducing air or oxygen into the water, thereby promoting the dissolution of oxygen in the water, improving water quality, and promoting the growth of microorganisms and the degradation of organic matter. A gas flow meter is also included to control the aeration intensity.

[0048] The connection between the effluent tank and SPNEDA reactor 4 is located above the connection between the inlet pipe of the reflux pump 3 and the connection between SPNEDA reactor 4. The connection between the influent tank 1 and SPNEDA reactor 4 is located at the bottom of SPNEDA reactor 4, and the connection between the effluent tank and SPNEDA reactor 4 is located at the top of SPNEDA reactor 4.

[0049] It also includes an inlet pump 2, which draws wastewater from the inlet tank 1 into the SPNEDA reactor 4; and a water bath circulation pump 8, whose inlet is connected to a constant temperature water tank 7 and to the interlayer between the inner and outer walls of the SPNEDA reactor 4. The connection between the water bath circulation pump 8 and the SPNEDA reactor 4 is located at the bottom of the SPNEDA reactor 4, while the connection between the constant temperature water tank 7 and the SPNEDA reactor 4 is located at the top of the SPNEDA reactor 4. This design allows water to enter from the top and exit from the bottom of the interlayer between the inner and outer walls of the SPNEDA reactor 4, resulting in faster water circulation and reduced temperature fluctuations in the SPNEDA reactor 4.

[0050] In this embodiment, the water bath circulation pump 8, the inlet pump 2, and the return pump 3 are all peristaltic pumps. This design uses a timer switch to control the running time of the inlet return and outlet pumps, modifying it to a CSBR (Cycle-flow Sequencing Batch Reactor) operating mode with a drainage ratio of 50%.

[0051] The experimental system involved in this embodiment is scaled up proportionally for industrial use. The corresponding facilities, such as the volume of the SPNEDA reactor, inlet tank, water bath, and pump flow rate, will be scaled up accordingly, and will not be described in detail again.

[0052] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention. In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A control method for an SPNEDA system, characterized in that, include: Step 1: Anaerobic stage: Add wastewater to the SPNEDA reactor until the liquid level reaches the preset position, then control the SPNEDA reactor to operate in anaerobic mode for 60 minutes. During this anaerobic period, the denitrifying bacteria in the SPNEDA reactor store carbon sources and heat the SPNEDA reactor. 25 to 35 minutes before the end of the anaerobic stage, add NH2OH at a concentration of 4 to 8 mg / L to the SPNEDA reactor. Step 2: Aerobic stage: Aerobic aeration is carried out in the SPNEDA reactor for 360 minutes. The ammonia-oxidizing bacteria in the SPNEDA reactor carry out autotrophic short-cut nitrification. Step 3: Anoxic stage: After 210 min of anoxic conditions, sedimentation is carried out for 35 min, followed by drainage. Anaerobic ammonia oxidizing bacteria in the SPNEDA reactor carry out anaerobic ammonia oxidation reaction, while denitrifying bacteria carry out endogenous denitrification. The denitrifying bacteria are endogenous denitrifying bacteria. In the anaerobic stage, they consume Gly to synthesize and store PHAs, and in the anoxic stage, they decompose PHAs to synthesize Gly. The method employs a system comprising: a DO / pH probe, a constant temperature water tank, an aeration pump, and an inlet tank, an SPNEDA reactor, and an outlet tank connected in sequence. The constant temperature water tank and the SPNEDA reactor are connected by an interlayer between their inner and outer walls. The aeration pump is used to aerate the SPNEDA reactor, and the DO / pH probe is used to detect the dissolved oxygen and pH value of the wastewater in the SPNEDA reactor.

2. The method according to claim 1, characterized in that: In step 1, 25 minutes before the end of the anaerobic stage, NH2OH at a concentration of 6 mg / L is added to the SPNEDA reactor.

3. The method according to claim 1, characterized in that: It also includes controlling the dissolved oxygen level in the SPNEDA reactor at each stage to be less than 0.8 mg / L and the pH value to be 7.2-8.

2.

4. The method according to claim 1, characterized in that: In step 2, the wastewater from the SPNEDA reactor is refluxed and stirred.

5. The method according to claim 1, characterized in that: In step 1, the temperature of the SPNEDA reactor is maintained at 28~32℃.

6. The method according to claim 1, characterized in that: In step 2, the wastewater at the top of the SPNEDA reactor is returned to the bottom of the SPNEDA reactor using an external reflux method.

7. The method according to claim 1, characterized in that: It also includes a return pump for returning wastewater from the top of the SPNEDA reactor to the bottom of the SPNEDA reactor.

8. The method according to claim 1, characterized in that: It also includes an aeration disc located at the top of the SPNEDA reactor and connected to an aeration pump.

Images