A method for controlling the startup of an integrated dual-short-range coupled anaerobic ammonium oxidation process based on ultra-short settling time for suspended sludge

Abstract

A method for controlling the startup of an integrated dual-short-range coupled anaerobic ammonia oxidation process based on ultra-short sedimentation time for suspended sludge belongs to the field of sewage biological treatment. The first stage: inoculate the full-process nitrification sludge in the SBR reactor, operate in an anoxic-aerobic mode, control the sedimentation time to 5-10 minutes, and control the system sludge age to 8-14 days. When the nitrite accumulation rate at the end of the aerobic stage is higher than 90%, the short-range nitrification startup is completed. In the second stage, inoculate a mobile anaerobic ammonia oxidation biofilm (filling ratio of 8-10%), operate in an anaerobic-aerobic-anoxic mode, and control the sedimentation time to 2-5 minutes. When the aerobic stage NH4 + Reduced and no NO2 ‑ Accumulation, while the anoxic section NH4 + and NO x ‑ The invention solves the problems of long startup time, insufficient biological retention and unstable total nitrogen removal effect of the existing integrated reactor.

Description

Technical Field

[0001] The present invention relates to a device and method for starting dual short-range coupled anaerobic ammonia oxidation by regulating suspended sludge based on ultra-short settling time, belonging to the field of sewage biological treatment. Background Art

[0002] In recent years, environmental quality standards and water pollutant emission standards have become increasingly stringent. Traditional biological treatment processes, however, face challenges such as low total nitrogen removal rates and high energy consumption, making it difficult for wastewater treatment to meet these standards. Therefore, the development and application of efficient, low-energy biological denitrification technologies is imperative. The discovery of anaerobic ammonium oxidation (ANAMMOX) has paved the way for innovation in wastewater denitrification. This technology reduces aeration energy consumption, is fully self-sustaining, requires no carbon source, produces little sludge, and achieves high denitrification efficiency, significantly reducing carbon and energy requirements.

[0003] Integrated anaerobic ammonium oxidation (i.e., simultaneous short-cut nitrification and anaerobic ammonium oxidation) is a new denitrification process that is widely used. It couples short-cut nitrification and anaerobic ammonium oxidation in the same system under low DO conditions. This process not only saves aeration and carbon source consumption and reduces sludge production, but also simplifies the operation and saves infrastructure and energy investment.

[0004] However, the application of this process in mainstream urban sewage still faces challenges. The main bottlenecks are: ① Short-range nitrification (NH4 + →NO2 - ) The source of nitrite nitrogen provided by the system is not stable enough. Since urban sewage and domestic sewage are low-ammonia nitrogen wastewater, they do not have the FA or FNA inhibitory effects of high-ammonia nitrogen wastewater systems. During long-term operation, it is often difficult to effectively inhibit nitrite oxidizing bacteria (NOB) and produce excessive nitrate nitrogen. Combined with the nitrate nitrogen produced by the anaerobic ammonium oxidation process, it is difficult for the effluent to meet the standards; ② The growth rate of anaerobic ammonium oxidizing bacteria (AnAOB) is low, the generation cycle is long, and it is easy to be lost with the effluent. It is difficult to achieve sufficient retention in the system, which leads to a long start-up time for anaerobic ammonium oxidation related processes and unstable and easily destroyed nitrogen removal effects.

[0005] In recent years, short-range denitrification (NO3 - →NO2 -) is considered to be an effective way to produce nitrite nitrogen, and compared with short-term nitrification, it is simple to control and can be maintained stably for a long time. In practice, the anaerobic section first stores the carbon source in the sewage as an internal carbon source, and the anoxic section performs endogenous short-term denitrification coupled with anaerobic ammonia oxidation to simultaneously remove ammonia nitrogen and nitrate nitrogen from the wastewater. Therefore, through the anaerobic / aerobic / anoxic operating mode, the endogenous short-term denitrification is coupled with the integrated anaerobic ammonia oxidation, which can remove the nitrate nitrogen produced by short-term nitrification and anaerobic ammonia oxidation, and no external carbon source is required to be added, further improving the total nitrogen removal rate of the system. Therefore, the integrated dual short-term coupled anaerobic ammonia oxidation process is a new, efficient and energy-saving denitrification process based on anaerobic ammonia oxidation, which is expected to achieve deep denitrification of urban domestic sewage.

[0006] Denitrification granular sludge is a promising wastewater treatment technology, offering advantages such as high denitrification efficiency, small footprint, low sludge production, and low energy consumption. It is a novel technology for wastewater treatment plants. Due to the large hydrophobic surface area and high EPS production of AnAOB, it has a high self-aggregation ability, which leads to the formation of anaerobic ammonium oxidation granular sludge. In anaerobic ammonium oxidation systems, the formation of anaerobic ammonium oxidation granular sludge helps increase AnAOB retention, thereby increasing the system's total nitrogen removal load.

[0007] The study found that the selection pressure caused by ultra-short sedimentation time is one of the conditions that effectively drives particle formation. In the early stage of ultra-short sedimentation time application, excessive suspended sludge can be discharged, resulting in a shorter sludge age (SRT), which is conducive to the washing of NOB and is expected to start short-range nitrification while promoting the granulation of flocs in suspended sludge. The feast-and-famine operation mode (such as: anoxic / aerobic, anaerobic / anoxic / aerobic) helps to select slow-growing microorganisms that promote particle stabilization (such as ammonia oxidizing bacteria (AOB), AnAOB, polyphosphate-accumulating bacteria (PAOs) and polysaccharide-accumulating bacteria (GAOs)). Inoculation of mature anaerobic ammonium oxidation sludge is beneficial to increase the abundance of anaerobic ammonium oxidation in the system and shorten the start-up time of anaerobic ammonium oxidation-related processes.

[0008] The present invention aims to start an integrated dual-short-range coupled anaerobic ammonium oxidation process by shortening the settling time to regulate the suspended sludge. First, under the anoxic / aerobic operation mode, the sludge retention time (SRT) is gradually shortened through a short settling time strategy to promote the discharge of light suspended flocs from the reactor and start short-range nitrification at the same time. Then, a mobile anaerobic ammonium oxidation biofilm is inoculated. By combining the mobile biofilm with a short settling time, the integrated dual-short-range coupled anaerobic ammonium oxidation process is started while promoting the granulation of suspended sludge. Short-range nitrification and endogenous short-range denitrification are coupled with anaerobic ammonium oxidation in one system, which greatly saves aeration energy consumption and can achieve deep denitrification of urban domestic sewage without the need for an external carbon source. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to provide a method for quickly and efficiently starting an integrated dual short-range coupled anaerobic ammonia oxidation process based on ultra-short sedimentation time to regulate suspended sludge, thereby solving the problems of slow start-up time, insufficient biological retention, and unstable total nitrogen removal effect of existing integrated reactors, and realizing deep denitrification of urban domestic sewage.

[0010] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0011] A method for starting an integrated dual-short-range coupled anaerobic ammonium oxidation process based on regulating suspended sludge is carried out in the following steps:

[0012] Step 1: Prepare SBR reactor, full nitrification sludge, and anaerobic ammonium oxidation biofilm sludge;

[0013] Step 2: Ultra-short settling time (SRT) is used to achieve short-range nitrification stage, which takes 20 to 30 days. The prepared full-range nitrification sludge is inoculated in the SBR reactor, and the sludge concentration (MLSS) is controlled at 3500 to 5000 mg / L, the temperature is controlled at 20 to 30°C, and the drainage ratio of the SBR reactor is 50%. The SBR reactor is operated in anoxic-aerobic mode, and one operation cycle includes four stages: water inlet, anoxic stirring, aerobic stirring, sedimentation and drainage. In the anoxic stage, when NO x - When all denitrification is completed, the process stops; during the aerobic stirring stage, the dissolved oxygen (DO) is controlled at 0.4-0.6 mg / L, and NH4 + Aeration and stirring are immediately stopped when all the nitrite is consumed. The settling time during this stage is controlled to 5-10 minutes. Light suspended flocs discharged with the effluent are not recycled, and the system sludge age is controlled to 8-14 days. Short-range nitrification is successfully initiated when the effluent nitrite accumulation rate exceeds 90% at the end of each cycle.

[0014] The third step: start the integrated dual short-range coupled anaerobic ammonia oxidation process stage, the time is 30 to 50 days, the temperature is controlled at 20 to 30 ° C, the sludge concentration (MLSS) is controlled at 3500 to 5000 mg / L, the temperature is controlled at 20 to 30 ° C, and the SBR reactor drainage ratio is 50%; put the prepared anaerobic ammonia oxidation biofilm filler into the SBR reactor, the filling ratio is controlled at 8 to 10%, and the biofilm filler moves with the stirring to increase the selective pressure on the suspended sludge. The SBR reactor is operated in an anaerobic-aerobic-anoxic mode, and an operating cycle includes four stages: water inlet, anaerobic stirring, aerobic stirring, anoxic stirring, sedimentation and drainage. The anaerobic stirring time is controlled at 40 to 120 minutes to promote internal carbon source storage; the dissolved oxygen (DO) in the aerobic stirring stage is controlled at 0.4 to 0.6 mg / L, when NH4 + When all the water is consumed, stop aeration immediately; during the anoxic stirring stage, when the effluent NOx - When all the denitrification is completed, the stirring is stopped. The sedimentation time of this stage is controlled at 2 to 5 minutes, and the light suspended flocs discharged with the effluent are not recycled. After gradual acclimation, when the aerobic section NH4 + Reduced and no NO2 - accumulation, while NH4 appears in the anoxic section + and NO x - When both decrease and the removal rate is higher than 80%, it means that the system has completed the startup of the integrated dual short-range coupled anaerobic ammonium oxidation process.

[0015] The first step of full nitrification sludge is suspended floc sludge with good nitrification activity; the anaerobic ammonium oxidation biofilm sludge is biofilm sludge with anaerobic ammonium oxidation activity.

[0016] The temperature of the SBR reactor is controlled at 20-30° C.; and the drainage ratio of the SBR reactor is 50%.

[0017] During operation, the COD, ammonia nitrogen, nitrite nitrogen, nitrate nitrogen, DO and pH of the inlet and outlet water can be measured to understand the reaction process in the SBR reactor.

[0018] During the reaction stage, the present invention strengthens the mixing of the bacterial colonies and the substrate in the reactor by combining mechanical stirring with aeration, and simultaneously strengthens the mutual contact and aggregation between the bacterial colonies.

[0019] In summary, the goal is to rapidly initiate an integrated dual-short-range coupled anaerobic ammonium oxidation (ANAMMOX) process by regulating suspended sludge through ultra-short settling times. First, under anoxic / aerobic operation, a short settling time strategy is used to gradually shorten the sludge retention time (SRT), promoting the discharge of lightweight suspended flocs from the reactor while simultaneously initiating short-range nitrification. A mobile ANAMMOX biofilm is then inoculated. By combining the mobile biofilm with a short settling time, the granulation of suspended sludge is promoted while simultaneously initiating the integrated dual-short-range coupled ANAMMOX process, achieving economical and efficient denitrification of urban domestic sewage.

[0020] Therefore, the method provided by the present invention for quickly starting an integrated dual short-range coupled anaerobic ammonium oxidation process by regulating suspended sludge in an ultra-short settling time has the following beneficial effects:

[0021] (1) The present invention uses an ultra-short sedimentation time strategy to create a light suspended sludge discharge system, effectively promoting the granulation of suspended sludge, shortening the sludge residence time, and quickly achieving short-range nitrification;

[0022] (2) The present invention inoculates an anaerobic ammonium oxidation biofilm during the startup of the integrated dual-short-range coupled anaerobic ammonium oxidation process. The biofilm moves under mechanical stirring and the ultra-short sedimentation time promotes sludge granulation, quickly realizes the coexistence system of granular sludge and biofilm, accelerates the startup of the integrated dual-short-range coupled anaerobic ammonium oxidation process, and enhances the denitrification effect and stability.

[0023] (3) The present invention couples short-range nitrification and endogenous short-range denitrification with anaerobic ammonium oxidation, which greatly saves aeration energy consumption and does not require external source addition, saving sewage treatment costs;

[0024] (4) The system of the present invention enriches and retains slow-growing microorganisms for a long time, and the sludge age is longer, which can reduce the production of excess sludge and reduce the cost of sludge treatment and disposal. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a denitrification performance diagram of the startup process of the integrated dual short-range coupled anaerobic ammonium oxidation process of the present invention. DETAILED DESCRIPTION

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and examples, but the present invention is not limited to these examples.

[0027] Example 1

[0028] The test water is domestic sewage from a residential area, and its water quality is as follows: COD concentration is 180-80 mg / L,

[0029] NH4 + -N concentration is 40~68mg / L, NO2 - -N and NO3 - -N concentration is less than 0.5mg / L; the carbon-nitrogen ratio is between 2.3 and 3.4, which is a typical low carbon-nitrogen ratio urban domestic sewage. The SBR reactor used in the experiment is made of organic glass, with an effective volume of 10L and a drainage ratio of 50%. The whole nitrification sludge is traditional urban sewage A 2 / O The return sludge from the secondary sedimentation tank and the anaerobic ammonium oxidation biofilm were taken from the integrated reactor for treating digestate wastewater.

[0030] The specific operation operations are as follows:

[0031] 1) Start short-cut nitrification (I): The inoculated fully nitrified sludge is fed into the SBR reactor to make the sludge concentration (MLSS) in the reactor 3500 mg / L. At this stage, the reactor operates in anoxic / aerobic mode, and one operation cycle includes: water inlet, anoxic stirring, aerobic stirring, rapid sedimentation and drainage. Aeration is controlled by a gas flow meter to control DO at 0.4-0.6 mg / L; the sedimentation time is controlled at 10 minutes, and the light suspended flocs discharged with the effluent are no longer recycled, and at this time the sludge age of the system gradually decreases from 14 days to 8 days. After 37 days of operation, the effluent nitrite accumulation rate is as high as over 90%, and the short-cut nitrification is successfully started (see Figure 1 ).

[0032] 2) Start the integrated dual short-cut coupled anaerobic ammonium oxidation process (II): inoculate anaerobic ammonium oxidation biofilm sludge in the SBR reactor where the short-cut nitrification has been started, and operate in anaerobic / aerobic / anoxic mode. Each cycle includes: water inlet, anaerobic stirring, aerobic stirring, anoxic stirring, rapid sedimentation and drainage. After 90 minutes of anaerobic stirring, hypoxic aeration is performed to control DO at 0.4-0.6 mg / L. When NH4 + When all NO is consumed, stop aeration immediately; the hypoxia time is 60 minutes. x - Denitrification is completed. At this point, the anaerobic section of the system stores the carbon source in the domestic sewage as an internal carbon source, the aerobic section short-range nitrification and anaerobic ammonium oxidation are carried out simultaneously, and the anoxic section internal short-range denitrification is coupled with anaerobic ammonium oxidation, and the precipitation time is controlled within 10 minutes. The test results show that the effluent at this stage is mainly a small amount of ammonia nitrogen, the total nitrogen in the effluent is less than 8 mg / L, and the total nitrogen removal rate can reach 90% (see Figure 1 ), can be widely used in the treatment of urban domestic sewage.

[0033] The reactor described in the present invention is an SBR reactor, but is also applicable to other types of high-efficiency biological denitrification reactors.

[0034] The above is a detailed introduction to the method of the present invention based on regulating the startup of an integrated dual short-range coupled anaerobic ammonia oxidation process for suspended sludge, and uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the present invention and its core ideas. At the same time, for those skilled in the art, according to the ideas of the present invention, several improvements and applications can be made in the specific implementation methods and application scopes, and these improvements and applications are also regarded as the scope of protection of the present invention.

Claims

1. A method for starting an integrated dual short-range coupled anaerobic ammonium oxidation process based on ultra-short settling time regulation of suspended sludge, characterized in that The following steps are involved: Step 1: Prepare SBR reactor, full nitrification sludge, and anaerobic ammonium oxidation biofilm sludge; The second step: ultra-short settling time (SRT) is used to achieve short-range nitrification, which takes 20 to 30 days. The SBR reactor is inoculated with fully nitrified sludge, with the sludge concentration (MLSS) controlled at 3500 to 5000 mg / L, the temperature at 20 to 30°C, and the SBR reactor discharge ratio at 50%. The SBR reactor operates in anoxic-aerobic mode. One operation cycle includes four stages: water inlet, anoxic stirring, aerobic stirring, sedimentation and drainage. In the anoxic stage, when NO x - When all denitrification is completed, the process stops; during the aerobic stirring stage, the dissolved oxygen DO is controlled at 0.4-0.6 mg / L, and NH4 + When all the nitrite is consumed, aeration and stirring are stopped immediately; the sedimentation time is controlled at 5-10 minutes, and the light suspended flocs discharged with the effluent are no longer recycled, and the sludge age of the system is controlled at 8-14 days; when the nitrite accumulation rate of the effluent is higher than 90% at the end of each cycle, the short-range nitrification is successfully started; The third step: start the integrated double short-range coupled anaerobic ammonium oxidation process stage, the time is 30 to 50 days, the temperature is controlled at 20 to 30 ° C; the drainage ratio of the SBR reactor is 50%; the anaerobic ammonium oxidation biofilm filler is put into the SBR reactor, the filling ratio is controlled at 8 to 10%, and the biofilm filler moves with the stirring to increase the selective pressure on the suspended sludge; the SBR reactor adopts the anaerobic-aerobic-anoxic mode of operation, and an operation cycle includes: water inlet, anaerobic stirring for 40 to 120 minutes, aerobic stirring to control DO at 0.4 to 0.6 mg / L, anoxic stirring, sedimentation and drainage; in the aerobic stirring stage, when NH4 + When all the water is consumed, stop aeration immediately; during the anoxic stirring stage, when the effluent NO x - When denitrification is completed, stirring is stopped; the sedimentation time is controlled at 2 to 5 minutes, and the light suspended flocs discharged with the effluent are no longer recycled; after gradual acclimation, when the aerobic section NH4 + Reduced and no NO2 - accumulation, while NH4 appears in the anoxic section + and NO x - When both decrease and the removal rate is higher than 80%, it means that the startup is completed; Step 4: Stable operation of the integrated dual short-range coupled anaerobic ammonium oxidation process stage; after the startup is completed, the SBR reactor still operates in an anaerobic-aerobic-anoxic mode, and the temperature is controlled at 20-30°C; the drainage ratio of the SBR reactor is 50%, and each operation cycle includes: water inlet, anaerobic stirring for 40-120 minutes, aerobic stirring to control DO at 0.4-0.6 mg / L, anoxic stirring, sedimentation for 2-5 minutes and drainage, wherein the aerobic stirring stage is when NH4 + Stop when all is consumed, during the anoxic stirring stage when NO x - Stop when all denitrification is completed.

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