Method for culturing salt-tolerant anaerobic denitrifying granular sludge and application thereof

Abstract

The present application relates to the technical field of water pollution prevention and treatment, and particularly relates to a culture method of salt-tolerant anaerobic denitrification granular sludge and application. The culture method comprises the following steps: inoculating flocculent sludge into an upflow anaerobic reactor, starting domestication until domestication is completed; additionally adding a granulation inducer into influent of the reactor, and controlling concentrations of components in the granulation inducer in the influent to be initial concentrations; the granulation inducer comprises sodium chloride, a soluble metal salt and a compatible solute; the soluble metal salt can dissociate positive charge ions in water, and is not sodium chloride; the concentrations of the components in the granulation inducer and the influent load of the reactor are increased at the same amplitude, flocculent sludge gradually completes granulation, and anaerobic denitrification granular sludge is obtained from the bottom of the reactor. By using the culture method provided by the present application, the operation is simple and easy to implement, the period of sludge granulation can be greatly shortened, and thus the overall efficiency of wastewater treatment is improved.

Description

Technical Field

[0001] This invention relates to the field of water pollution control technology, and in particular to a method for cultivating and applying salt-tolerant anaerobic denitrifying granular sludge. Background Technology

[0002] In the field of wastewater treatment, granular sludge has become one of the important technologies for wastewater treatment due to its excellent settling performance, high sludge loading and strong biological activity. Compared with the traditional activated sludge process, the granular sludge process can significantly improve the system's treatment efficiency and reduce problems such as sludge bulking and poor settling performance through the formation of granular sludge.

[0003] However, in practical applications, achieving rapid sludge granulation remains a significant challenge, particularly when treating wastewater containing high concentrations of nitrates from industries such as food, brewing, semiconductors, printed circuit boards, photovoltaics, electroplating, and metal surface treatment. Inoculating with flocculent sludge results in slow settling, low sludge loading, large reactor footprint, and poor resistance to shock loads. Inoculating with granular sludge, on the other hand, can increase sludge loading and reduce footprint. However, the limited microbial community in high-salt anaerobic denitrification sludge, lacking filamentous bacteria, makes sludge granulation difficult and typically results in a long cultivation period. Summary of the Invention

[0004] To address or partially address the problems existing in related technologies, this invention provides a method for cultivating and applying salt-tolerant anaerobic denitrifying granular sludge.

[0005] This invention provides a method for cultivating salt-tolerant anaerobic denitrifying granular sludge, comprising:

[0006] S1. Inoculate the upflow anaerobic reactor with flocculent sludge and start the acclimatization process until it is complete; S2. Add an additional granulation inducer to the reactor feed water and control the concentration of each component in the granulation inducer in the feed water to the initial concentration. The particle formation inducer comprises: sodium chloride, a soluble metal salt, and a compatible solute; the soluble metal salt can dissociate into positively charged ions in water and is not sodium chloride; S3. By increasing the reactor influent load and the concentration of each component in the granulation inducer by the same amount, the flocculent sludge gradually completes granulation, and anaerobic denitrification granular sludge is obtained from the bottom of the reactor.

[0007] Furthermore, the soluble metal salt is at least one of soluble calcium salt and soluble magnesium salt; the compatible solute is selected from one or more of glycerol, trehalose, betaine, tetrahydropyrimidine, mannitol, glycine, and sorbitol.

[0008] Furthermore, in step S1, the moisture content of the inoculated flocculent sludge is 95%~99%, and the inoculation amount is 20%~40% of the effective volume of the reactor.

[0009] Furthermore, in step S1, when the nitrate concentration in the reactor influent reaches 500 mg / L, the influent C / N ratio is greater than 4, and the complete denitrification removal rate is greater than 90%, the acclimation is completed.

[0010] Further, in step S2, the initial concentrations of each component are: sodium chloride 0.4%~3.2%, soluble metal salt 0.4~3.2 mM, and compatible solute 0.08~0.62 mM; the concentration of the soluble metal salt is calculated as positively charged ions.

[0011] Furthermore, in step S2, when the nitrate removal rate of the influent water reaches more than 80% after complete denitrification in the reactor and has been running stably for 1-3 days, this step ends and proceeds to step S3.

[0012] Further, step S3 specifically includes: S301. Increase the reactor influent load and the concentration of each component in the granulation inducer by a preset percentage; the preset percentage is 10%~50%; S302. After the nitrate in the influent has been completely denitrified and removed by the reactor at a rate of over 80%, and after continuous and stable operation for 1-3 days, repeat step S301, and the flocculent sludge will gradually be granulated.

[0013] Furthermore, during steps S2 and S3, the following steps are also included: controlling the sludge layer height to be less than 80% of the reactor height by adjusting the reactor upflow velocity.

[0014] The present invention also provides a salt-tolerant anaerobic denitrifying granular sludge, which is obtained by cultivating according to any one of the above methods.

[0015] The present invention also provides an application of the above-mentioned method for cultivating salt-tolerant anaerobic denitrifying granular sludge in wastewater treatment.

[0016] The method for cultivating salt-tolerant anaerobic denitrifying granular sludge provided by this invention can include the following beneficial effects: 1) This cultivation method accelerates sludge granulation by adding a granulation inducer to the influent and increasing the granulation rate proportionally with the influent load. The granulation inducer is readily available, easy to prepare, and can be added to the influent at a preset concentration. The operation is simple and easy to implement.

[0017] 2) The added granulation inducers regulate the adaptability of microorganisms to high-salt environments by controlling the morphology of EPS polymer membranes on the outside of microorganisms, controlling the synthesis and accumulation of intracellular osmotic pressure regulating substances, and controlling extracellular secretion. This reduces the salt and substrate concentrations that stimulate microbial protein metabolism and avoids excessive EPS secretion. At the same time, positively charged ions are an important component of extracellular polysaccharides and proteins, promoting adsorption and adhesion between microorganisms. This changes the electronegativity of the cell surface and promotes microbial aggregation, thereby maintaining sludge granulation under high-salt conditions.

[0018] 3) Experiments have shown that the cultivation method provided by this invention can significantly shorten the sludge granulation cycle from about 140 days to about 17 days, thereby improving the overall efficiency of wastewater treatment.

[0019] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the invention. Attached Figure Description

[0020] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same parts.

[0021] Figure 1 This is a photograph of the granulation process of the inoculated flocculent sludge in Example 1 of the present invention. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular forms “a,” “the,” and “the” used in this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0024] It should be understood that although the terms "first," "second," "third," etc., may be used in this invention to describe various information, this information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this invention, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Thus, features defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0025] The first embodiment of the present invention provides a method for cultivating salt-tolerant anaerobic denitrifying granular sludge, comprising: S1. Inoculate the upflow anaerobic reactor with flocculent sludge and start the acclimatization process until it is complete; S2. Add an additional granulation inducer to the reactor feed water and control the concentration of each component in the granulation inducer in the feed water to the initial concentration. The particle formation inducer comprises: sodium chloride, a soluble metal salt, and a compatible solute; the soluble metal salt can dissociate into positively charged ions in water and is not sodium chloride; S3. By increasing the reactor influent load and the concentration of each component in the granulation inducer by the same amount, the flocculent sludge gradually completes granulation, and anaerobic denitrification granular sludge is obtained from the bottom of the reactor.

[0026] In the cultivation method provided in this embodiment: Step S1 involves inoculating with flocculent sludge and acclimatizing the sludge. Inoculating with flocculent sludge rapidly establishes the initial microbial community, and acclimatization allows the microorganisms to gradually adapt to the high-salt environment, activating denitrification and providing a biomass basis for subsequent granulation. The inoculated flocculent sludge can be derived from excess sludge from municipal wastewater treatment plants; preferably, the water content of the inoculated flocculent sludge is 95%–99%, and the inoculation amount is 20%–40% of the effective reactor volume. Acclimatization in this step can employ methods commonly used by those skilled in the art, such as gradually increasing the influent nitrate concentration. In this preferred embodiment, acclimatization is complete when the reactor influent nitrate concentration reaches 500 mg / L, the influent C / N ratio is greater than 4, and the complete denitrification removal rate is greater than 90%.

[0027] Step S2 is the addition of a granulation inducer, the purpose of which is to accelerate the formation of sludge granules. This granulation inducer includes: sodium chloride, a soluble metal salt, and a compatible solute; the soluble metal salt can dissociate into positively charged ions in water, and is not sodium chloride.

[0028] This granulation inducer, as a water pollution control agent, promotes sludge granulation in the following way: Under high-salt conditions, microorganisms secrete extracellular polymeric substances (EPS) in response to salt stress. EPS coating the microbial surface not only provides protection but also alters cell surface electronegativity, promoting microbial aggregation and thus facilitating the formation of flocculent sludge and maintaining its granular structure. Sodium chloride in the composition serves to stimulate the production of EPS by microorganisms.

[0029] The inventors of this application have also discovered that excessive EPS secretion can form a polymeric membrane on the surface of granular sludge, blocking the gas exchange channels of the particles, leading to a decrease in granular sludge density, sludge floating, and disintegration. This, in turn, reduces the rate of sludge granulation or causes instability in the formed granular structure. This application innovatively introduces positively charged ions and compatible solutes to regulate the adaptability of microorganisms to high-salt environments by controlling the morphology of the EPS polymeric membrane on the outside of the microorganisms, controlling the synthesis and accumulation of intracellular osmotic pressure regulating substances, and controlling extracellular secretion. This reduces the stimulation of microbial protein metabolism by salt and substrate concentrations, avoiding excessive EPS secretion. Simultaneously, positively charged ions are important components of extracellular polysaccharides and proteins, promoting adsorption and adhesion between microorganisms, thereby altering the cell surface electronegativity and promoting microbial aggregation, thus maintaining sludge granulation under high-salt conditions.

[0030] The soluble metal salt in the particle-forming inducer is preferably at least one of soluble calcium salt and soluble magnesium salt, specifically one or more of calcium chloride, magnesium chloride, calcium sulfate, and magnesium sulfate. The aforementioned compatible solute is selected from one or more of glycerol, trehalose, betaine, tetrahydropyrimidine, mannitol, glycine, and sorbitol.

[0031] The inventors of this application have discovered that the method of adding the granulation inducer affects the granulation process of sludge. The granulation process is fastest when the granulation inducer is added at the same rate as the influent load. Therefore, in this application, an initial concentration of the granulation inducer is added first, and then the concentration is increased at the same rate as the influent load. This corresponds to steps S2 and S3 in this embodiment. In step S2, the initial concentrations of each component are preferably as follows: sodium chloride 0.4%~3.2%, soluble metal salt 0.4~3.2 mM, and compatible solute 0.08~0.62 mM; in this application, the concentration of the soluble metal salt is calculated as positively charged ions. More preferably, the initial concentrations of each component are: sodium chloride 0.5%~3.0%, soluble metal salt 0.5~3 mM, and compatible solute 0.1~0.6 mM.

[0032] Preferably, in step S2, after the influent nitrate removal rate by complete denitrification in the reactor reaches over 80% and the reactor operates stably for 1-3 consecutive days, this step ends, and the process proceeds to step S3. Step S3 involves increasing the reactor influent load and the granulation inducer concentration by a uniform margin to promote the granulation of flocculent sludge. Step S3 is preferably defined as follows: S301. Increase the reactor influent load and the concentration of each component in the granulation inducer by a preset percentage; the preset percentage is 10%~50%, more preferably 20%~30%; S302. After the nitrate in the influent has been completely denitrified and removed by the reactor at a rate of over 80%, and after continuous and stable operation for 1-3 days, repeat step S301, and the flocculent sludge will gradually be granulated.

[0033] The applicant also discovered that excessive granulation inducer content in the influent can lead to problems such as sludge particle calcification. Therefore, as a preferred embodiment, in step S3, when the concentration of each component of the granulation inducer in the influent reaches the upper limit concentration, the concentration of each component in the granulation inducer in the influent is stopped from being increased. The upper limit concentration is preferably as follows: sodium chloride 3.2%, soluble metal salt 3.2 mM, and compatible solute 0.08~0.62 mM; more preferably, sodium chloride 3%, soluble metal salt 3 mM, and compatible solute 0.6 mM.

[0034] To improve the efficiency of sludge-substrate exchange and control sludge collision and aggregation, the process of steps S2 and S3 includes the following step: controlling the sludge layer height to be below 80% of the reactor height by adjusting the reactor upflow velocity. Specifically, this can be achieved by: The upflow velocity inside the reactor is adjusted to 1 m / h to 5 m / h by using an external circulation pump. The upflow velocity is dynamically adjusted to control the sludge layer height to be less than 80% of the reactor height. For example, when the sludge layer height is close to 80%, the upflow velocity is reduced or the external circulation pump is turned off.

[0035] The second embodiment of the present invention also provides a salt-tolerant anaerobic denitrification granular sludge, which is cultivated according to the method described in the first embodiment. The specific implementation method is the same as that in the first embodiment, and will not be repeated here. This salt-tolerant anaerobic denitrification granular sludge has a high nitrate removal rate and its structure remains stable in a high-salt environment, making it less prone to sludge floating and disintegration.

[0036] The third embodiment of the present invention also provides an application of the above-mentioned method for cultivating salt-tolerant anaerobic denitrifying granular sludge in wastewater treatment. Specifically: The salt-tolerant anaerobic denitrifying granular sludge was cultured according to the method described in the first embodiment above. By feeding water into the reactor at full capacity, denitrification can be achieved.

[0037] or, The salt-tolerant anaerobic denitrifying granular sludge was cultivated according to the method described in the first embodiment above. The cultured salt-tolerant anaerobic denitrifying granular sludge is inoculated into the wastewater treatment reactor according to the treatment load requirement, acclimatized, and then fed into the reactor at full load to achieve the denitrification nitrogen removal target.

[0038] This salt-tolerant anaerobic denitrification granular sludge has a high nitrate removal rate and remains structurally stable in high-salt environments, making it less prone to sludge floating or disintegration.

[0039] This method is particularly suitable for denitrification treatment of wastewater containing high concentrations of nitrates.

[0040] As can be seen from the above, the method for cultivating salt-tolerant anaerobic denitrifying granular sludge provided in this embodiment of the invention has the following advantages: 1) This cultivation method accelerates sludge granulation by adding a granulation inducer to the influent and increasing the granulation rate proportionally with the influent load. The granulation inducer is readily available, easy to prepare, and can be added to the influent at a preset concentration. The operation is simple and easy to implement.

[0041] 2) The added granulation inducers regulate the adaptability of microorganisms to high-salt environments by controlling the morphology of EPS polymer membranes on the outside of microorganisms, controlling the synthesis and accumulation of intracellular osmotic pressure regulating substances, and controlling extracellular secretion. This reduces the salt and substrate concentrations that stimulate microbial protein metabolism and avoids excessive EPS secretion. At the same time, positively charged ions are an important component of extracellular polysaccharides and proteins, promoting adsorption and adhesion between microorganisms. This changes the electronegativity of the cell surface and promotes microbial aggregation, thereby maintaining sludge granulation under high-salt conditions.

[0042] 3) Experiments have shown that the cultivation method provided by this invention can significantly shorten the sludge granulation cycle from about 140 days to about 17 days, thereby improving the overall efficiency of wastewater treatment.

[0043] The technical solution of the present invention will be further described below with reference to specific embodiments: The detection methods for each indicator in the following experimental examples refer to the following standards: The particle size of granular sludge was determined using a laser particle size analyzer, specifically the Mastersize2000 from Malvern, UK. Chemical oxygen demand (COD), nitrate nitrogen (NO3) - -N), nitrite nitrogen (NO2) - -N) The determination shall be made in accordance with the standard method of "Methods for Monitoring and Analysis of Water and Wastewater, Fourth Edition".

[0044] Where specific experimental steps or conditions are not specified in the embodiments, they can be performed according to the conventional experimental steps or conditions described in the literature in this field. All raw materials or instruments used are commercially available conventional products, including but not limited to those used in the embodiments of this application.

[0045] Example 1 1. Inoculate the upflow anaerobic reactor with residual flocculent sludge from the municipal wastewater treatment plant for acclimatization and start-up. The residual sludge has a moisture content of 95% and the inoculation amount is 20% of the effective volume of the reactor.

[0046] The acclimatization process is as follows: The reactor influent is simulated high-concentration nitrate wastewater. At the beginning of the acclimatization stage, the nitrate concentration in the influent is 100 mg / L and the C / N ratio is 4. The nitrate concentration in the influent is gradually increased. When the nitrate concentration in the influent reaches 500 mg / L and the complete denitrification removal rate is greater than 90%, the acclimatization is completed.

[0047] 2. Add an additional granulation inducer to the influent of the acclimated reactor. The composition of the granulation inducer is as follows: sodium chloride, calcium chloride and betaine. Adjust the concentration of sodium chloride in the influent to 0.5%, calcium chloride to 0.5 mM and betaine to 0.1 mM.

[0048] 3. When the nitrate removal rate of the influent water reaches more than 80% after complete denitrification in the reactor and has been running stably for 2 consecutive days, increase the influent load and the concentration of each component of the granulation inducer by 30%. After the nitrate removal rate of the influent water reaches more than 80% after complete denitrification in the reactor and has been running stably for 2 consecutive days, continue to increase the influent load and the concentration of the additives in the same way as above.

[0049] 4. During steps 2 and 3, the upflow velocity of the reactor is dynamically controlled. The specific operation is as follows: In the early stage of cultivation, the upflow velocity in the reactor is controlled at 1 m / h. After the nitrate concentration in the influent gradually increases and the gas production of the reactor increases, the upflow velocity in the reactor is increased to a maximum of 5 m / h. When the sludge layer height reaches 80% of the reactor height, the upflow velocity is reduced or the external circulation pump of the reactor is turned off.

[0050] 5. Using a reactor without additives as a control, after observing the appearance of granular sludge in the reactor, record the running time and analyze the particle size d50 of the granular sludge. When the volume distribution fraction of sludge particles larger than 340 μm reaches more than 50% (d50>340 μm), it can be considered that the sludge in the reactor has basically achieved granulation.

[0051] Figure 1The diagram illustrates the granulation process of the inoculated sludge: A represents the inoculated flocculent sludge, B represents the agglomerated flocculent sludge after the influent load and the concentration of each component of the granulation inducer were increased twice, and C represents the sludge that has completed granulation.

[0052] Example 2 1. Inoculate the upflow anaerobic reactor with residual flocculent sludge from the municipal wastewater treatment plant for acclimatization and start-up. The residual sludge has a moisture content of 99% and the inoculation amount is 40% of the effective volume of the reactor.

[0053] The acclimation process is as follows: The reactor influent is high-concentration nitrate wastewater generated by a photovoltaic company. At the beginning of the acclimation phase, the nitrate concentration in the influent is diluted to 300 mg / L, and an external carbon source is added to maintain the C / N ratio of the reactor influent at 4.5. Acclimation is complete when the nitrate concentration in the influent reaches 500 mg / L and the complete denitrification removal rate is greater than 90%.

[0054] 2. Add an additional granulation inducer to the influent of the acclimated reactor. The composition of the granulation inducer is as follows: sodium chloride, magnesium chloride and tetrahydropyrimidine. Adjust the concentration of sodium chloride in the influent to 0.5%, the concentration of magnesium chloride to 0.5 mM, and the concentration of tetrahydropyrimidine to 0.1 mM.

[0055] 3. After the influent nitrate removal rate reaches over 80% through complete denitrification in the reactor and has been running stably for 2 consecutive days, increase the influent load and the concentration of each component of the granulation inducer by 20%. Continue increasing the influent load and additive concentration as described above after the influent nitrate removal rate reaches over 80% through complete denitrification in the reactor and has been running stably for 2 consecutive days. During this process, if the sludge has not yet granulated when the influent load is increased to 800 mg / L of nitrate concentration in the photovoltaic wastewater, continue increasing the influent additive concentration. Stop increasing the additive concentration when the influent salinity reaches 3%, the magnesium chloride concentration reaches 3 mM, and the tetrahydropyrimidine concentration reaches 0.6 mM.

[0056] 4. Same as Example 1.

[0057] 5. Same as Example 1.

[0058] Example 3 The only difference from Example 1 is that betaine in the granulation inducer is replaced with mannitol.

[0059] Example 4 The only difference from Example 1 is that betaine in the granulation inducer is replaced with glycine.

[0060] Example 5 The only difference from Example 1 is that betaine in the granulation inducer is replaced with sorbitol.

[0061] Comparative Example 1 The only difference from Example 1 is: In step 3, the reactor influent load is increased by the same amount, while the concentrations of each component of the particulate inducer in the influent remain unchanged. That is, in step 3, the concentrations of sodium chloride, calcium chloride, and betaine in the influent are maintained at 0.5%, 0.5 mM, and 0.1 mM, respectively.

[0062] Comparative Example 2 The only difference from Example 1 is: In step 2, the concentrations of sodium chloride, calcium chloride, and betaine in the influent are adjusted to 3.0%, 3 mM, and 0.6 mM, respectively.

[0063] In step 3, the reactor influent load is increased by only one constant amount, while the concentrations of each component of the granulation inducer in the influent remain unchanged. That is, in step 3, the influent concentrations are maintained as follows: sodium chloride at 3.0%, calcium chloride at 3 mM, and betaine at 0.6 mM. The above embodiments and comparative examples use simulated high-concentration nitrate wastewater and photovoltaic wastewater as research objects to examine the feasibility and effectiveness of the technical solution of this application. The salt-tolerant denitrification granular sludge cultivation conditions of the above embodiments and comparative examples are shown in Table 1: Table 1. Cultivation status of salt-tolerant denitrifying granular sludge in Examples 1-5 and Comparative Examples 1-2

[0064] As shown in Table 1: As can be seen from Examples 1-5, the reactors operating using the rapid cultivation method of salt-tolerant anaerobic denitrification granular sludge achieved sludge granulation in the 17th to 20th day, while the reactors without additives required 140 to 150 days to achieve sludge granulation. This shows that the method provided in this application can significantly shorten the granular sludge cultivation cycle and is also applicable to real industrial wastewater.

[0065] Comparative Examples 1 and 2 show that adding a granulation inducer during the granular sludge cultivation process, but keeping the concentration constant, helps to shorten the granulation cycle, but sludge granulation still requires 68 days and 75 days respectively.

[0066] The nitrate removal rate data show that the nitrate removal rate of the salt-tolerant denitrifying granular sludge cultured using the method of this application is significantly higher than that of other experimental groups.

[0067] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for cultivating salt-tolerant anaerobic denitrifying granular sludge, characterized in that, include: S1. Inoculate the upflow anaerobic reactor with flocculent sludge and start the acclimatization process until it is complete; S2. Add an additional granulation inducer to the reactor feed water and control the concentration of each component in the granulation inducer in the feed water to the initial concentration. The particulate inducing agent includes: sodium chloride, soluble metal salt and compatible solute; The soluble metal salt can dissociate into positively charged ions in water and is not sodium chloride; the soluble metal salt is at least one of soluble calcium salt and soluble magnesium salt; the compatible solute is selected from one or more of glycerol, trehalose, betaine, tetrahydropyrimidine, mannitol, glycine, and sorbitol; the initial concentrations of each component are: sodium chloride 0.4%~3.2%, soluble metal salt 0.4~3.2 mM, and compatible solute 0.08~0.62 mM; the concentration of the soluble metal salt is expressed as positively charged ions. S3. By increasing the reactor influent load and the concentration of each component in the granulation inducer by the same amount, the flocculent sludge gradually completes granulation, and anaerobic denitrification granular sludge is obtained from the bottom of the reactor.

2. The cultivation method according to claim 1, characterized in that, In step S1, the moisture content of the inoculated flocculent sludge is 95% to 99%, and the inoculation amount is 20% to 40% of the effective volume of the reactor.

3. The cultivation method according to claim 1, characterized in that, In step S1, when the nitrate concentration in the reactor influent reaches 500 mg / L, the influent C / N ratio is greater than 4, and the complete denitrification removal rate is greater than 90%, the acclimation is completed.

4. The cultivation method according to claim 1, characterized in that, In step S2, when the nitrate removal rate of the influent water reaches more than 80% after complete denitrification in the reactor and has been running stably for 1-3 days, this step ends and proceeds to step S3.

5. The cultivation method according to claim 1, characterized in that, Step S3 specifically involves: S301. Increase the reactor influent load and the concentration of each component in the granulation inducer by a preset percentage; the preset percentage is 10%~50%; S302. After the nitrate in the influent has been completely denitrified and removed by the reactor at a rate of over 80%, and after continuous and stable operation for 1-3 days, repeat step S301, and the flocculent sludge will gradually be granulated.

6. The cultivation method according to claim 1, characterized in that, The process of steps S2 and S3 also includes the following steps: controlling the sludge layer height to be less than 80% of the reactor height by adjusting the reactor upflow velocity.

7. A salt-tolerant anaerobic denitrifying granular sludge, characterized in that, It is obtained by the method according to any one of claims 1 to 6.

8. The application of the method for cultivating salt-tolerant anaerobic denitrifying granular sludge according to any one of claims 1 to 6 in wastewater treatment.

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