Conditioner for realizing rapid granulation of aerobic granular sludge and improving settleability

Abstract

The invention discloses a conditioner for realizing rapid granulation of aerobic granular sludge and improving settleability, relates to the field of aerobic granular sludge, and aims to solve the problems of low AGS formation speed, poor AGS stability and low settleability caused by low aeration rate. The conditioner is composed of mycelium pellets, mature aerobic granular sludge, a biological flocculant and activated carbon; the adding proportion of the conditioner is as follows: the mycelium pellets and the mature aerobic granular sludge are added according to the proportion that V mycelium pellets / V30min settled sludge is 20%-50% and VAGS / V30min settled sludge is 20%-50%, the adding amount of the biological flocculant is 0.2%-1% of the effective volume of a reactor, and the adding amount of the activated carbon is 0.2-0.8 g per liter of the effective volume of the reactor. A low aeration strategy is adopted, energy consumption is reduced, and better energy-saving and environment-friendly effects are achieved. According to the method, a large amount of granular sludge can be induced to be formed in only 17 days, basic granulation is realized in 25 days, and the formed aerobic granular sludge is compact in structure, regular in form and high in stability.

Description

Technical Field

[0001] The invention belongs to the field of aerobic granular sludge, and in particular relates to a conditioning agent for realizing rapid granulation of aerobic granular sludge and improving sedimentation performance. Background Art

[0002] Biological treatment technology for sewage occupies an important position in the field of wastewater treatment. Aerobic granular sludge (AGS) has become a hot spot in sewage treatment technology research because of its good sedimentation performance, efficient removal of organic matter and nitrogen and phosphorus, and low operating energy consumption. However, the traditional AGS culture process usually takes a long time, often taking weeks or even months to form stable granular sludge, which limits its promotion and practicality in engineering applications. Therefore, accelerating the formation of granular sludge and improving its stability are the key to the promotion of aerobic granular sludge in actual engineering. At present, studies have proposed a variety of strategies to promote the rapid granulation of sludge, among which exogenous addition strategy is an important method. According to the nature of the added material, the existing exogenous addition methods are mainly divided into the following three categories:

[0003] 1) Physically enhanced addition. The formation mechanism of this type of method is based on the induced nucleus hypothesis, which emphasizes the role of the core of the added particles. Common added particles include: inert particles (sand, zeolite, clay, etc.) or high surface area carriers (activated carbon, glass beads, etc.). For example, the invention patent for a method of using iron-carbon micropowder to control sludge swelling and achieve sludge granulation (CN119143279A) promotes the granulation process by providing nucleus formation points and enhancing microbial adhesion. However, the limitations of this method are that some granular materials are difficult to fully combine with the sludge, and the effect may be reduced due to loss during long-term operation; at the same time, long-term stability is still affected by operating conditions, such as changes in hydraulic shear force may cause the granular sludge to loosen or disintegrate.

[0004] 2) Chemically regulated addition. This method is based on the extracellular polymers and induced nucleus hypothesis, which believes that the stability of sludge flocs is affected by the surface charge of particles. The surface of sludge particles is usually negatively charged, and there is electrostatic repulsion between them, which affects the agglomeration of particles. The addition of chemical additives (such as divalent or polyvalent metal ions, polymer flocculants) can promote the secretion of EPS, neutralize the negative charge on the surface of microbial cells, reduce the electrostatic repulsion between cells, promote flocculation and granulation; at the same time, by forming a bridging structure, the binding force of sludge particles is enhanced and the stability of particles is improved. For example, the invention patent for a process for rapid cultivation of aerobic granular sludge (CN113428975A) introduces calcium ions into the water to promote the formation of the second messenger c-di-GMP, stimulate the secretion of EPS, and thus accelerate the granulation process. However, the limitation of this method is that long-term addition may increase the operating cost of sewage treatment and affect subsequent sludge treatment and resource utilization.

[0005] 3) Biological regulation type addition. This method is based on the hypothesis of extracellular polymers and filamentous bacteria, and believes that the formation of granular sludge not only depends on physical or chemical factors, but is also deeply affected by microbial behavior. Add specific functional bacterial communities, microbial carriers, bioflocculants or EPS, and use their biological metabolic characteristics to enhance the sludge granulation process. And through competition and synergy between microorganisms, the community structure is optimized to keep the granular sludge stable under different environmental conditions. For example, the invention patent of a method for promoting aerobic sludge granulation by mycelial balls (CN106006950B) uses mycelial balls to attach and fix flocculent sludge on the surface of mycelium, and also increases the diversity and richness of microorganisms in the system, so as to achieve the purpose of accelerating aerobic sludge granulation. However, the limitation of this method is that the succession of microbial populations has great uncertainty, and the introduction of specific microorganisms may be inhibited by the competition of the microbial community of the original sludge, resulting in limited granulation process. At the same time, biological regulation methods often need to be combined with specific environmental conditions, such as suitable C / N ratio, appropriate hydraulic load, high aeration volume, etc., which are greatly affected by operating parameters. Summary of the invention

[0006] In order to solve the problems of slow AGS formation speed, poor AGS stability and low settling performance caused by low aeration volume, the present invention provides a conditioning agent for realizing rapid granulation of aerobic granular sludge and improving settling performance.

[0007] The invention discloses a conditioning agent for realizing rapid granulation of aerobic granular sludge and improving sedimentation performance. The conditioning agent is composed of mycelial pellets, mature aerobic granular sludge, biological flocculant and activated carbon. The conditioning agent is added in the following proportions: mycelial pellets and mature aerobic granular sludge are added in the following proportions: V 菌丝球 / V 30min沉降污泥 =20%~50%,V AGS / V 30min沉降污泥 =20% to 50% of the ratio of addition, the amount of the bioflocculant added is 2‰ to 10‰ of the effective volume of the reactor, and the amount of activated carbon added is 0.2g to 0.8g of activated carbon per liter of the effective volume of the reactor.

[0008] Furthermore, the mycelial balls and mature aerobic granular sludge are prepared according to V 菌丝球 / V 30min沉降污泥 =30%~40%,V AGS / V 30min沉降污泥 =30% to 40% of the ratio of addition, the amount of the bioflocculant added is 2‰ to 5‰ of the effective volume of the reactor, and the amount of activated carbon added is 0.4g to 0.6g of activated carbon per liter of the effective volume of the reactor.

[0009] Furthermore, the conditioning agent is added into the reactor, and the aeration rate of the reactor is 0.2-0.7 L / min.

[0010] Furthermore, the conditioning agent is added into the reactor, and the reactor is operated in an intermittent flow mode, with n cycles per day set, and the aeration volume is 0.2-0.7 L / min.

[0011] Furthermore, the conditioning agent is added to the reactor, and the reactor is operated without selecting a pressure.

[0012] Furthermore, the mycelial pellets are prepared as follows: a spore suspension is inoculated into a mycelial pellet growth medium, and the medium is placed in a shaker at 28-30°C for 3-5 days to obtain mycelial pellets, and mycelial pellets with a particle size of 1-1.5 mm are sieved with a sieve and stored at 4°C for later use.

[0013] Furthermore, the fungal spores selected for the mycelial balls are Aspergillus niger spores.

[0014] Furthermore, the reactor is an SBR reactor, UASB-SBR or MBR reactor.

[0015] Furthermore, by using the conditioning agent, the initial aerobic granular sludge formation time is within 17 days, and the aerobic granular sludge is stably granulated and formed within 25 days.

[0016] Furthermore, the COD of the sewage treated by the conditioning agent is 200-600 mg / L.

[0017] The principle of the present invention is as follows:

[0018] The added mycelium balls and mature granular sludge provide the initial skeleton in the system. The fiber support of the mycelium structure enhances the mechanical strength of the granular sludge, making it difficult for the initial particles to disintegrate under the action of hydrodynamic shear, while providing an attachment carrier for the microbial community, accelerating the agglomeration and growth of flocculent sludge. Subsequently, the bridging effect of the bioflocculant and activated carbon becomes the key driving force for granulation. The bioflocculant changes the surface charge of the sludge particles, reduces electrostatic repulsion, enhances van der Waals forces and hydrogen bonds, and promotes the secretion of EPS, thereby enhancing the binding force between sludge particles and reducing particle dispersion. The porous structure of activated carbon provides additional adsorption sites, and through capillary force and adsorption, the bridging between sludge flocs is more stable, effectively reducing the dispersion and disintegration of particles. In addition, the activated carbon particles themselves have a higher density, which improves the sedimentation performance of the particles. At the same time, the present invention adopts a low aeration strategy, which reduces the shear damage of granular sludge, reduces energy consumption, and achieves better energy-saving and environmental protection effects compared to the traditional high aeration method, while maintaining sufficient oxygen supply to support microbial metabolism and promote the sustained and stable development of granulation.

[0019] The present invention has the following beneficial effects:

[0020] The present invention adopts low aeration (0.2-0.7L / min) and optimized dosing ratio (V 菌丝球 / V 30min沉降污泥 =20~50%,V AGS / V 30min沉降污泥 =20-50%, 2‰-10‰ of biological flocculation, 0.2-0.8g / L of activated carbon), to construct an AGS granulation synergistic system. Under this condition, it only takes 17 days to induce the formation of a large amount of initial granular sludge, and the basic granulation of the system can be achieved within 25 days. Compared with the traditional method, the AGS formed by the present invention has a tighter structure, a more regular morphology, and higher stability. At the same time, the strategy is simple to operate, has no secondary pollution, and has low cost, providing an efficient and feasible technical solution for the rapid construction of granular sludge in sewage treatment projects. The present invention adopts a low aeration strategy, which reduces the shear damage of granular sludge and energy consumption compared to the traditional high aeration method, and achieves better energy-saving and environmental protection effects. At the same time, it maintains sufficient oxygen supply to support microbial metabolism and promotes the continuous and stable development of granulation.

[0021] The present invention uses mycelial balls and mature aerobic granular sludge as the original skeleton to accelerate the aggregation and growth of flocculent sludge. The bridging effect of biological flocculants and activated carbon further accelerates the granulation process and improves the sludge settling performance. The aerobic granular sludge formed has a compact structure, regular morphology, and high stability. It not only solves the problem of slow sludge settling speed in traditional reactors, especially SBR reactors, but also can greatly shorten the sludge granulation time and improve the operating stability of sludge particles. In addition, the present invention adopts a low aeration strategy to reduce energy consumption compared to traditional high aeration methods, thereby achieving better energy-saving and environmental protection effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The sludge morphology is observed under a microscope; (a) d1; (b) d6; (c) d12; (d) d17; (e) d25; (dN-day N);

[0023] Figure 2 This is the graph of the change in reactor sludge particle size;

[0024] Figure 3 This is the graph showing changes in the reactor sludge settling performance;

[0025] Figure 4 This is the three-dimensional fluorescence spectrum analysis diagram of reactor sludge EPS;

[0026] Figure 5 Schematic diagram of SBR reactor. DETAILED DESCRIPTION

[0027] In order to make the objectives, technical solutions and advantages of the embodiments of the present invention more clearly understood, the spirit of the contents disclosed by the present invention will be described in detail below. After understanding the embodiments of the contents of the present invention, any technician in the relevant technical field can change and modify them according to the techniques taught by the contents of the present invention without departing from the spirit and scope of the contents of the present invention.

[0028] The exemplary embodiments of the present invention and the description thereof are used to explain the present invention, but are not intended to limit the present invention.

[0029] Embodiment 1:

[0030] 1. Preparation of mycelial pellets

[0031] Take 0.02 mL of spore suspension and inoculate it into 100 mL of mycelial pellet growth medium, and place it in a shaker at 28°C and 160 rpm for 5 days to obtain mycelial pellets. Use a sieve to sieve mycelial pellets with a particle size of 1.5 mm, wash the surface of the mycelial pellets with deionized water, and soak the cultured mycelial pellets in deionized water and store them at 4°C for later use.

[0032] 2. Obtain flocculent sludge and mature aerobic granular sludge

[0033] Flocculent sludge is taken from the activated sludge of the secondary sedimentation tank of the sewage treatment plant. The selection criteria are: the sludge is flocculent, dark brown in color, has a high content of inorganic matter, and is rich in biological phase;

[0034] Mature aerobic granular sludge was obtained from a laboratory SBR reactor ( Figure 5 ).

[0035] 3. Add mycelium balls, mature aerobic granular sludge and conditioners

[0036] The test device is an SBR reactor, the main body of the reactor is 100cm high, 75mm in diameter, and has an effective volume of 2.8L. Two sampling ports are set at 20cm and 60cm from the bottom, a water inlet is set at 20cm from the top, and a vent is set at the bottom. The outside of the reaction device is equipped with a water inlet peristaltic pump, a water outlet solenoid valve, an aeration pump, a microporous aeration head, inlet and outlet pipes and other accessories.

[0037] Aerobic activated sludge with a sludge concentration (MLSS) of 3000 mg / L was added to the SBR reactor, and mycelial balls and mature aerobic granular sludge were added at V 菌丝球 / V 30min沉降污泥 =30%, V AGS / V 30min沉降污泥 =30% was added to the SBR reactor, and then 20 mL of bioflocculant and 1.5 g of activated carbon were added, and the reactor was started.

[0038] 4. Reactor startup and aerobic granular sludge cultivation

[0039] The reactor was operated in an intermittent flow mode, with 4 cycles per day. A single experimental cycle was 360 minutes, including 15 minutes of water inlet, 15 minutes of water outlet, 240 minutes of aeration, 45 minutes of sedimentation, and 45 minutes of remaining static time. The aeration rate was controlled by a gas flow meter at 0.5 L / min. The reactor used artificial simulated wastewater, with anhydrous sodium acetate as the carbon source at a concentration of 400 mg / L and ammonium chloride as the nitrogen source at a concentration of 20 mg / L.

[0040] During the start-up and operation of the reactor, the particle size, appearance, sedimentation performance and other properties of the aerobic granular sludge are regularly observed, and the effluent quality is regularly measured to analyze and judge the degree of sludge granulation, the stability of granular sludge operation and the removal effect of artificial simulated wastewater. At a specific time, a sample is prepared from a uniformly mixed sludge-water mixture to analyze the microbial community structure of the sludge sample.

[0041] Results: In this embodiment, when the reactor was operated for 17 days, the average particle size of the sludge reached 200μm, and granular sludge was initially formed. When it was operated for 25 days, the average particle size of the sludge was 321.606μm, and more than half of the granular sludge exceeded 200μm, and the system basically achieved granulation. The sedimentation performance of the reactor sludge was good. The pollutant removal effect was good, with a COD removal rate of 88.14%, a total nitrogen removal rate of 77.54%, and ammonia nitrogen removal rate of 96.47%. The accumulated nitrite nitrogen and nitrate nitrogen concentrations were 0.04mg / L and 3.0mg / L, respectively. The effluent water quality was good and basically met the first-level A standard for effluent from urban sewage treatment plants. The EPS content in the reactor increased significantly after the addition of the conditioning agent, reaching a peak at about 12 days, and then tended to stabilize. By 25 days, the abundance of protein and polysaccharide was 36.42mg / gSS and 5.36mg / gSS, respectively, and the PN / PS ratio was 6.79. The 25th-day sludge EPS samples were tested using a three-dimensional fluorescence infrared spectrometer and found that tryptophan substances were significant fluorescence peaks, which contributed to the formation of particles. Analysis of the microbial community structure showed that compared with the original sludge samples, the abundance of Proteobacteria in the experimental group sludge samples increased to 81.03% on the 25th day, and the genus level succession in the reactor was relatively high, which was suitable for the rapid formation of aerobic granular sludge.

[0042] It can be seen that in the early stage of the experiment of this embodiment, a large amount of flocculent sludge is adsorbed on the mycelial balls and AGS particles, and the additives mainly play the role of carriers. As the mycelial balls and AGS are broken under the action of hydraulic shear force during the operation of the reactor, the bacterial fragments, broken mycelial structures, and broken particles are mixed in the sludge, becoming the core and skeleton of the aggregate, and gradually evolving into an inducing effect, continuously inducing and forming aerobic granular sludge. The particle formation rate is significantly faster than that of the control group. After the initial addition of the conditioning agent, it was found that the sedimentation capacity of the reactor was significantly increased, and the EPS secretion was significantly increased. Through the analysis of the microbial community structure, it was found that compared with the original sludge sample, the abundance of Proteobacteria in the sludge sample after the reactor was operated for a period of time increased. The analysis may be due to the fact that Proteobacteria can secrete extracellular polymers, making the agglomeration simpler and the adhesion ability stronger. The abundance of Actinomycetes in the reactor sample increased compared to the original sludge sample added, and this trend of change is also conducive to the growth of aerobic granular sludge.

[0043] Embodiment 2:

[0044] 1. Preparation of mycelial pellets

[0045] Take 0.03 mL of appropriate spore suspension and inoculate it into 100 mL of mycelial pellet growth medium, and place it in a shaker at 30°C and 160 rpm for 3 days to obtain mycelial pellets. Use a sieve to sieve mycelial pellets with a particle size of 1.5-2 mm, wash the surface of the mycelial pellets with deionized water, and soak the cultured mycelial pellets in deionized water and store them at 4°C for later use.

[0046] 2. Obtain flocculent sludge and mature aerobic granular sludge

[0047] Flocculent sludge is taken from the activated sludge of the secondary sedimentation tank of the sewage treatment plant. The selection criteria are: the sludge is flocculent, dark brown in color, has a high content of inorganic matter, and is rich in biological phase;

[0048] Mature aerobic granular sludge was taken from a laboratory SBR reactor.

[0049] 3. Add mycelium balls, mature aerobic granular sludge and conditioners

[0050] The test device used was a self-designed SBR reactor, with a main body height of 100 cm, a diameter of 75 mm, an effective volume of 2.8 L, two sampling ports 20 cm and 60 cm from the bottom, a water inlet 20 cm from the top, and a vent at the bottom. The reaction device was equipped with an inlet peristaltic pump, an outlet solenoid valve, an aeration pump, a microporous aeration head, inlet and outlet pipes and other accessories.

[0051] Aerobic activated sludge with a sludge concentration (MLSS) of 3000 mg / L was added to the SBR reactor, and mycelial balls and mature aerobic granular sludge were added at V菌丝球 / V 30min沉降污泥 =40%, V AGS / V 30min沉降污泥 =40% was added to the SBR reactor, and then 25 mL of bioflocculant and 2 g of activated carbon were added, and the reactor was started.

[0052] 4. Reactor startup and aerobic granular sludge cultivation

[0053] The reactor was operated in an intermittent flow mode, with 4 cycles per day. A single experimental cycle was 360 minutes, including 15 minutes of water inlet, 15 minutes of water outlet, 260 minutes of aeration, 30 minutes of sedimentation, and 40 minutes of remaining static time. The aeration rate was controlled by a gas flow meter at 0.2L / min. The reactor used artificial simulated wastewater, with anhydrous sodium acetate as the carbon source at a concentration of 400mg / L and ammonium chloride as the nitrogen source at a concentration of 20mg / L.

[0054] During the start-up and operation of the reactor, the particle size, appearance, sedimentation performance and other properties of the aerobic granular sludge are regularly observed, and the effluent quality is regularly measured to analyze and judge the degree of sludge granulation, the stability of granular sludge operation and the removal effect of artificial simulated wastewater. At a specific time, a sample is prepared from a uniformly mixed sludge-water mixture to analyze the microbial community structure of the sludge sample.

[0055] Results: In this embodiment, when the reactor was operated for 14 days, the average particle size of the sludge reached 200μm, and granular sludge was initially formed. When it was operated for 25 days, the average particle size of the sludge was 384.549μm, and the granular sludge exceeding 200μm exceeded 65%, and the system basically achieved granulation. The sedimentation performance of the reactor sludge was good. The pollutant removal effect was good, with a COD removal rate of 95.27%, a total nitrogen removal rate of 75.18%, and ammonia nitrogen removal rate of 98.47%. The accumulated nitrite nitrogen and nitrate nitrogen concentrations were 0.02mg / L and 4.2mg / L, respectively. The effluent water quality was good and basically met the first-level A standard for effluent from urban sewage treatment plants. The EPS content in the reactor increased significantly after the addition of the conditioning agent, reaching a peak at about 9 days, and then tended to stabilize. By 25 days, the abundance of protein and polysaccharide was 39.82mg / gSS and 4.87mg / gSS, respectively, and the PN / PS ratio was 8.18. The 25th-day sludge EPS samples were tested using a three-dimensional fluorescence infrared spectrometer and found that tryptophan substances were significant fluorescence peaks, which contributed to the formation of particles. Analysis of the microbial community structure showed that compared with the original sludge samples, the abundance of Proteobacteria in the sludge samples of the experimental group increased to 83.14% on the 25th day, which was suitable for the rapid formation of aerobic granular sludge.

Claims

1. A conditioning agent for achieving rapid granulation of aerobic granular sludge and improving sedimentation properties, characterized in that The conditioning agent is composed of mycelium balls, mature aerobic granular sludge, biological flocculant and activated carbon; the addition ratio of the conditioning agent is: mycelium balls and mature aerobic granular sludge according to V 菌丝球 / V 30min沉降污泥 =20%~50%,V AGS / V 30min沉降污泥 =20% to 50% of the ratio of addition, the amount of the bioflocculant added is 2‰ to 10‰ of the effective volume of the reactor, and the amount of activated carbon added is 0.2g to 0.8g of activated carbon per liter of the effective volume of the reactor.

2. A conditioning agent for achieving rapid granulation of aerobic granular sludge and improving sedimentation properties according to claim 1, characterized in that The mycelial balls and mature aerobic granular sludge are prepared according to V 菌丝球 / V 30min沉降污泥 =30%~40%, V AGS / V 30min沉降污泥 =30% to 40% of the ratio of addition, the amount of the bioflocculant added is 2‰ to 5‰ of the effective volume of the reactor, and the amount of activated carbon added is 0.4g to 0.6g of activated carbon per liter of the effective volume of the reactor.

3. A conditioning agent for achieving rapid granulation of aerobic granular sludge and improving sedimentation properties according to claim 1, characterized in that The conditioning agent is added into the reactor, and the aeration rate of the reactor is 0.2-0.7 L / min.

4. The conditioning agent for achieving rapid granulation of aerobic granular sludge and improving sedimentation properties according to claim 1, characterized in that The conditioning agent is added into the reactor, and the reactor is operated in an intermittent flow mode, and a single-day cycle is set to n cycles, and the aeration volume is 0.2-0.7 L / min.

5. The conditioning agent for achieving rapid granulation of aerobic granular sludge and improving sedimentation properties according to claim 1, characterized in that The conditioning agent is added to the reactor, and the reactor is operated without selecting a pressure.

6. The conditioning agent for achieving rapid granulation of aerobic granular sludge and improving sedimentation properties according to claim 1, characterized in that The mycelium pellets are prepared as follows: spore suspension is inoculated into mycelium pellet growth medium, and placed in a shaker at 28-30°C for 3-5 days to obtain mycelium pellets, mycelium pellets with a particle size of 1-1.5 mm are sieved with a sieve, and stored at 4°C for later use.

7. A conditioning agent for achieving rapid granulation of aerobic granular sludge and improving sedimentation properties according to claim 1 or 6, characterized in that The fungal spores selected for the mycelium balls are Aspergillus niger spores.

8. A conditioning agent for achieving rapid granulation of aerobic granular sludge and improving sedimentation properties according to claim 1, 3, 4 or 5, characterized in that The reactor is an SBR reactor, a UASB-SBR or an MBR reactor.

9. A conditioning agent for achieving rapid granulation of aerobic granular sludge and improving sedimentation properties according to claim 1 or 2, characterized in that By using the conditioning agent, the initial aerobic granular sludge formation time is within 17 days, and the aerobic granular sludge is stably granulated and formed within 25 days.

10. The conditioning agent for achieving rapid granulation of aerobic granular sludge and improving sedimentation properties according to claim 1, characterized in that The COD of sewage treated by the conditioning agent is 200-600 mg / L.

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