Method and apparatus for acclimating salt tolerant activated sludge

Abstract

The application discloses a method and device for domesticating salt-tolerant activated sludge, and belongs to the technical field of microbial culture and sewage treatment device. In the prior art, the domestication of salt-tolerant activated sludge is achieved by gradually increasing the salinity, and the obtained sludge has poor genetic adaptability and a long domestication period. The application provides a method for domesticating salt-tolerant activated sludge, which comprises the following steps: inputting fresh sludge with a sludge concentration MLSS of 5000-6000 mg / L and MLSS / MLVSS greater than or equal to 0.8 into a domestication device; the domestication device comprises an anoxic reaction zone and an aerobic reaction zone which are in communication with each other; the concentration of salt in the control system is 3-5%; when the CODcr removal rate is less than or equal to 30%, the CODcr concentration gradient is gradually increased by 500-1000 mg / L in a step-by-step manner through the following methods: increasing the nutrition dosage, increasing the aeration amount of the aerobic reaction zone, returning the sludge in the aerobic reaction zone to the anoxic reaction zone, supplementing fresh sludge, discharging inactivated sludge and the like. The obtained salt-tolerant activated sludge has good genetic property and a short domestication period.

Description

Technical Field

[0001] This invention belongs to the technical field of microbial culture and wastewater treatment devices, and more specifically, relates to a method and device for acclimatizing salt-tolerant activated sludge. Background Technology

[0002] Activated sludge process, a widely used biological wastewater treatment technology, primarily relies on the microbial community within activated sludge to degrade organic matter in wastewater. However, in high-salinity environments, the traditional activated sludge process faces significant challenges. The high concentration of inorganic salts in high-salinity wastewater inhibits microbial activity, affecting their growth and metabolism, thus reducing wastewater treatment efficiency. Acclimation treatment of saline wastewater is feasible. During acclimation, microorganisms balance intracellular osmotic pressure through osmotic pressure regulation mechanisms, protecting the protoplasm within the cells. These regulatory mechanisms include accumulating low-molecular-weight substances to form new extracellular protective layers, regulating metabolic pathways, and altering gene composition.

[0003] Currently, methods for salt tolerance acclimation of activated sludge can be mainly divided into two types: the bacterial introduction method and the natural acclimation method. The bacterial introduction method involves adding salt-tolerant bacteria to the seed sludge to alter the population structure and improve its tolerance to high salinity. However, this method is costly and has limited feasibility. The natural acclimation method involves gradually increasing the salinity of the wastewater, but the population diversity is relatively low, and even after successful acclimation, the suitable salinity that the sludge can tolerate still needs to be controlled below 5%. Existing technologies disclose the gradual increase of wastewater salinity to acclimate sludge, such as Chinese invention application publication number CN106396321A, application date June 17, 2016, invention title "A method for acclimatizing activated sludge in high-salinity organic wastewater by increasing salt tolerance through pressurization". The disclosed scheme gradually increases the wastewater salinity in the initial seed sludge in a set manner, with a set number of days for each acclimatization level. The acclimatization process is carried out in an SBR operation mode in a closed constant pressure reactor, with the absolute pressure controlled at 0.2-0.4 MPa, and the aeration rate keeping the dissolved oxygen in the reactor below 10 mg / L, which can effectively improve the removal efficiency of organic matter in high-salinity wastewater of 3%-5%. This scheme has the following shortcomings: (1) The acclimatization period is long, during which the microorganisms need to gradually adapt to the gradually increasing salt concentration. (2) The microorganisms in the acclimatized activated sludge have a limited tolerance range to salt and are sensitive to environmental changes. When the chloride ion environment changes suddenly, the adaptability of the microorganisms will disappear immediately. (3) The adaptation of microorganisms during the acclimatization process is a temporary physiological adjustment and does not have genetic characteristics. This means that once the environment changes, the adaptability of microorganisms may be lost rapidly. (4) Compared with the method of directly using salt-tolerant bacteria or diluting the influent, the acclimatization method of gradually increasing the salt concentration is more complicated to operate and requires precise control of the rate of increase of salt concentration and acclimatization conditions. (5) Although the method of gradually increasing the salt concentration can theoretically improve the salt tolerance range and treatment efficiency of the system, in practice it may increase economic costs due to the need for longer acclimatization time and complex operation.

[0004] Directly acclimating sludge to enable it to degrade organic matter in a high-salt environment presents certain difficulties, mainly due to the following reasons: (1) High-salt environments have inhibitory and toxic effects on microbial growth and metabolism. Microorganisms in high-salt environments need to balance intracellular osmotic pressure through osmotic pressure regulation mechanisms. These mechanisms include accumulating low-molecular-weight substances to form new extracellular protective layers, regulating metabolic pathways, and altering gene composition. These physiological adjustments are temporary, lack genetic characteristics, and are sensitive to environmental changes. Once the environment changes, the microorganisms' adaptability will immediately disappear. (2) The concentration of activated sludge decreases in the early stages of acclimation because the increase in salt solution is toxic to microorganisms, causing some microorganisms to die, resulting in negative growth. During the acclimation process, microorganisms need to gradually adapt to the high-salt environment, which may be very slow and requires high operating conditions. (3) Salinity enhances the respiration and cytolysis of microorganisms, reducing the biodegradability and degradation degree of organic matter, thus decreasing the removal rate and degradation rate of organic matter. (4) The source of inoculum sludge needs to be considered during the cultivation and acclimation of salt-tolerant activated sludge. Activated sludge from different sources exhibits differences in salt tolerance acclimation, and the rate of salinity increase also affects the final treatment effect.

[0005] Therefore, developing a new method for acclimating salt-tolerant activated sludge to improve its treatment effect in a higher salinity range is of great significance for the treatment of practical high-salinity wastewater. Summary of the Invention

[0006] 1. The problem to be solved

[0007] To address the problems in existing technologies where salt-tolerant activated sludge is acclimatized through a gradient increase in salinity, resulting in poor genetic adaptability and a long acclimatization period, this invention provides a method for acclimatizing salt-tolerant activated sludge. Furthermore, this invention also provides an apparatus for acclimatizing salt-tolerant activated sludge.

[0008] 2. Technical Solution

[0009] The technical solution adopted in this invention is as follows:

[0010] Based on the objectives of this invention, a first aspect of this invention provides a method for acclimating salt-tolerant activated sludge, comprising the steps of:

[0011] S1. Fresh sludge is introduced into the acclimatization device. The fresh sludge has a moisture content of 98% to 99%, VSS / TSS ≥ 0.8 ± 0.1, and SVI of 85 to 150. The acclimatization device includes an anaerobic-anoxic reaction zone and an aerobic reaction zone that are interconnected. At the beginning of acclimatization, the sludge concentration MLSS is controlled at 5000 to 6000 mg / L.

[0012] S2. The salt concentration in the control system is 3-5%. When the CODcr removal rate is ≤30%, it is achieved through...

[0013] Increase nutrient addition to the domestication device so that the proportion of external carbon source reaches 1 / 4 to 1 / 5; and / or,

[0014] Increase the aeration rate in the aerobic reaction zone to achieve a dissolved oxygen level of 5–6 mg / L; and / or,

[0015] The sludge from the aerobic reaction zone is returned to the anaerobic-anoxic reaction zone, with the return ratio controlled at 100%–200%; and / or,

[0016] Replenish with fresh sludge, with the newly added sludge accounting for 1 / 5 to 1 / 3 of the total sludge volume; and / or,

[0017] The amount of deactivated sludge discharged externally accounts for 1 / 5 to 1 / 4 of the total amount of sludge discharged externally, until the CODcr removal rate is ≥75%.

[0018] S3. Gradually increase the CODcr concentration gradient in increments of 500–1000 mg / L, with an acclimatization period of 5–10 days for each CODcr concentration gradient; control the sludge age to 20–25 days; when the sludge concentration is ≥10000–12000 mg / L, discharge the sludge and control the sludge concentration to remain stable.

[0019] The acclimation process ends when the influent CODcr ≥ 10000 mg / L and the removal rate ≥ 70%, thus obtaining the salt-tolerant activated sludge.

[0020] According to any embodiment of the first aspect of the present invention, the method for acclimating salt-tolerant activated sludge involves controlling the salt concentration in the system by adding salts; the salts are sodium chloride and sodium sulfate, and the concentration is controlled to be 3 ≤ CODcr / SO4. 2- ≤10.

[0021] The method used to control the salt concentration in the system described herein can also be used to directly add wastewater with high salinity to the system to adjust the salt concentration in the system to 3-5%.

[0022] In wastewater treatment, CODcr (Chemical Oxygen Demand) and SO4 2- The ratio of (sulfate ions) is an important parameter, when CODcr / SO4 2- When the ratio is between 3 and 10: it promotes microbial metabolic balance; improves organic matter removal efficiency; enhances the system's shock resistance; optimizes electron flow distribution; and improves salt tolerance: during the acclimation process of salt-tolerant activated sludge, gradually increasing the salinity is more conducive to the cultivation of salt-tolerant bacteria. Suitable CODcr / SO4 ratios... 2-The ratio helps improve the tolerance of sludge microorganisms to salt concentration, thereby enhancing the salt tolerance of sludge; stable operation: maintaining appropriate CODcr / SO4 2- The ratio helps maintain the stable operation of activated sludge systems, especially in high-salinity environments; it also reduces sludge production: a suitable CODcr / SO4 ratio 2- The ratio helps reduce the production of excess sludge because the activity of sulfate-reducing bacteria is reduced, thereby lowering the cost of sludge treatment and disposal.

[0023] According to any embodiment of the first aspect of the present invention, the method for acclimating salt-tolerant activated sludge includes the following: the carbon source is wastewater carbon source and glucose in a mass ratio of 4:1; the CODcr:N:P ratio is 100-300:5:1.

[0024] Maintaining a suitable CODcr:N:P ratio is crucial for microbial growth, ensuring that microorganisms are not limited in their growth due to a lack of carbon, nitrogen, or phosphorus sources. In denitrification, the optimal C / N ratio is 5:1, while the proliferation ratio of heterogeneous microorganisms in aerobic tanks is 100–300:5:1. Maintaining this ratio improves nitrogen removal efficiency, especially in anoxic tanks for total nitrogen removal. The addition of industrial glucose can improve sludge settling and dewatering properties. In wastewater treatment, the addition of industrial glucose can promote the biodegradation of certain recalcitrant pollutants. By combining different reaction rates and types of carbon sources, the carbon source and process residence time can be better matched, increasing microbial diversity and activity, thereby improving nitrogen removal efficiency.

[0025] According to any embodiment of the first aspect of the present invention, the method for acclimating salt-tolerant activated sludge is provided, wherein the wastewater carbon source is a biopharmaceutical wastewater carbon source and does not contain degradable organic matter; and the fresh sludge is taken from the biochemical sludge thickening tank of a food processing plant wastewater treatment station.

[0026] Pharmaceutical wastewater, as a carbon source, generally lacks recalcitrant organic matter, which facilitates the screening and acclimatization of microorganisms with stronger salt tolerance. Fresh sludge from food industry wastewater contains microbial communities adapted to the characteristics of food wastewater; these microorganisms may contribute to improving system stability and shock resistance during salt tolerance acclimation. Furthermore, fresh sludge from food industry wastewater may contain highly active microorganisms that can effectively degrade organic matter, improving organic matter removal efficiency.

[0027] According to the salt-tolerant activated sludge acclimation method of any embodiment of the first aspect of the present invention, the oxidation-reduction potential of the anoxic reaction zone is controlled at -100mV to +100mV; and the oxidation-reduction potential of the aerobic reaction zone is controlled at +200mV to +400mV.

[0028] Under anoxic conditions, maintaining an ORP between -100 mV and +100 mV helps promote biological reactions such as denitrification. This ORP range indicates that the system is in a region where facultative anaerobic microorganisms are active, performing aerobic respiration above +100 mV and anaerobic respiration below +100 mV.

[0029] Maintaining the oxidation-reduction potential (ORP) within the range of +200mV to +400mV in the aerobic reaction zone promotes the oxidative decomposition of organic matter. Under aerobic conditions, a higher ORP value indicates a stronger oxidizing capacity, which is beneficial for the degradation of organic matter by aerobic microorganisms and improves COD removal efficiency. Optimizing the nitrification process: Aerobic microorganisms can grow at values ​​above +100mV, with an optimal range of +300 to +400mV. Within this ORP range, the growth of nitrifying bacteria and the nitrification reaction are promoted, thereby increasing the ammonia nitrogen conversion rate. Controlling the aerobic aeration rate through ORP control avoids insufficient or excessive aeration time, ensuring the quality of the treated effluent while saving energy.

[0030] According to the acclimatization method of salt-tolerant activated sludge according to any embodiment of the first aspect of the present invention, the anaerobic-anoxic reaction zone is aerated once every 4 to 6 hours.

[0031] Aeration provides oxygen to microorganisms, promoting nitrification and converting ammonia nitrogen into nitrite and nitrate—a crucial step in biological denitrification. Appropriate aeration frequency helps control activated sludge bulking, as over-aeration can cause sludge flocs to break down, while under-aeration can lead to sludge bulking. Aeration accelerates the degradation and oxidation of organic matter, significantly improving wastewater treatment efficiency and effluent quality. Appropriate aeration frequency also enhances sludge floc formation, improves sludge settling properties, and reduces suspended solids in the effluent. Over-aeration is detrimental to the normal growth and reproduction of activated sludge and may cause sludge flocs to break down. Aerating every 4–6 hours can prevent this, maintaining the healthy state of the sludge.

[0032] According to any embodiment of the first aspect of the present invention, a method for acclimating salt-tolerant activated sludge includes adding a flocculant to the aerobic reaction zone.

[0033] As described herein, the flocculant is preferably activated carbon powder, with an addition amount of 0.01 kg carbon / m³. 3 Wastewater.

[0034] The addition of flocculants can improve the settling performance of sludge, reduce sludge bulking, and thus increase the settling speed and efficiency. Adding flocculants promotes the formation of aerobic granular sludge, improves the settling performance of granular sludge, stabilizes sludge concentration, and results in good effluent quality. Appropriate addition of flocculants can reduce sludge production because flocculants promote sludge aggregation and settling, reducing suspended solids in the system.

[0035] A second aspect of the present invention provides an acclimatization device for salt-tolerant activated sludge, used to implement the acclimatization method for the salt-tolerant activated sludge, the acclimatization device comprising: an anaerobic-anoxic reactor and an aerobic reactor;

[0036] The upper parts of the anaerobic-anoxic reactor and the aerobic reactor are connected by a pipe;

[0037] The lower parts of the anaerobic-anoxic reactor and the aerobic reactor are connected by a sludge return pipe, which is also connected to a sludge return pump.

[0038] Both the anaerobic-anoxic reactor and the aerobic reactor are equipped with microporous aerators at the bottom.

[0039] The anaerobic-anoxic reactor is equipped with fluidized bed packing.

[0040] The aerobic reactor is equipped with a stirrer;

[0041] The aerobic reactor is equipped with a sludge discharge port.

[0042] According to any embodiment of the second aspect of the present invention, the salt-tolerant activated sludge acclimatization apparatus, wherein the fluidized bed packing occupies ≥60% of the volume of the anaerobic-anoxic reactor.

[0043] According to any embodiment of the second aspect of the present invention, the acclimation apparatus for salt-tolerant activated sludge has a height-to-diameter ratio of 2.5 to 5 for both the anaerobic-anoxic reactor and the aerobic reactor.

[0044] As described herein, the preferred specifications for both the anaerobic-anoxic reactor and the aerobic reactor are a height of 1.5m, a diameter of 0.6m, and a total effective volume of 0.3m³. 3 The material is high-strength acrylic sheet. A row of sampling valves is installed on the walls of both the anaerobic-anoxic reactor and the aerobic reactor. Each reactor is equipped with a pH meter, dissolved oxygen meter, and thermometer. The bottom of the aerobic reactor has a sludge discharge port for collecting acclimated sludge.

[0045] 3. Beneficial effects

[0046] (1) The salt-tolerant activated sludge acclimation method of the present invention: a. High-efficiency salt tolerance acclimation: By gradually acclimating activated sludge in a high-salt environment (3% to 5%), the present invention successfully screened out strains with high salt tolerance. These strains can maintain activity in extreme environments, significantly improving the salt tolerance of the wastewater treatment system. b. Optimized sludge management: By controlling the selection of fresh and suitable sludge, the sludge concentration MLSS (5000 to 6000 mg / L), and the initial CODcr concentration during acclimation, the activity and treatment efficiency of the initial sludge are ensured. At the same time, by controlling the sludge concentration (sludge discharge when ≥10000 to 12000 mg / L) to remain stable, sludge management is optimized. c. Gradually increasing CODcr treatment efficiency: By gradually increasing the CODcr concentration gradient in increments of 500–1000 mg / L and controlling each acclimatization cycle to 5–10 days, this scheme gradually enhances the adaptability of activated sludge to high CODcr loads, ultimately achieving the goal of a removal rate ≥70% when the influent CODcr ≥10000 mg / L. d. Flexible nutrient and aeration control: When the CODcr removal rate is ≤30%, treatment conditions can be flexibly adjusted by increasing nutrient addition, increasing aeration, sludge recirculation, supplementing with fresh sludge, or increasing sludge discharge to improve the CODcr removal rate to ≥75%, thus enhancing the system's adaptability and stability. e. Environmentally friendly and cost-effective: Biological treatment improves the treatment efficiency of high-salinity wastewater, reduces the need for chemical treatment, lowers treatment costs, and reduces the risk of secondary pollution to the environment. f. Broad application prospects: This method is not only applicable to industrial wastewater treatment but can also be extended to other wastewater treatment fields requiring high salt tolerance, demonstrating broad application prospects. g. Simple and efficient operation: By gradually increasing the salinity and CODcr gradient, the acclimation process is simplified, making it easy to operate and manage, and suitable for wastewater treatment facilities of various sizes. It enriches the types of activated sludge, increases the sludge's adaptability to salinity, and allows for direct screening, acclimation, and cultivation under high-salt conditions, shortening the acclimation cycle and accelerating the elimination of activated sludge with poor high-salt tolerance.

[0047] (2) The salt-tolerant activated sludge acclimatization device of the present invention: a. Flexible and stable control: The split design allows for independent control of the anaerobic-anoxic reactor and the aerobic reactor, enabling the system to recover quickly after disturbance. This design improves the flexibility and stability of the system, allowing each reactor to be optimized according to specific treatment needs. b. Reduced inhibition: The short-cut nitrification stage in the split process can reduce certain toxins and organic matter, preventing them from directly entering another reactor, thereby reducing the inhibitory effect on activated sludge. This is particularly important for treating wastewater containing toxins and organic matter, improving the system's resistance to shock loads. c. Improved volumetric utilization and efficiency: The aerobic tank (aerobic module) is in a constant aeration state, increasing the tank volumetric utilization and improving equipment utilization; the blower pressure is stable and efficient; the air oxygen conversion utilization rate is high, and the volumetric load and sludge load are high. e. Enhanced biofilm reaction: The anaerobic-anoxic reactor is equipped with fluidized bed packing, and the aerobic reactor is filled with activated carbon powder and has a stirrer. These designs help to form a stable biofilm, enhance the contact between microorganisms and pollutants in wastewater, and improve mass transfer efficiency.

[0048] Instruction manual illustrations

[0049] Figure 1 This is a schematic diagram of the acclimatization device for salt-tolerant activated sludge in the embodiments of this application;

[0050] In the picture:

[0051] 1. Anaerobic-anoxic reactor; 2. Aerobic reactor; 3. Fluidized bed packing; 4. Microporous aerator; 5. Sampling port; 6. Sludge discharge port; 7. Mixer; 8. Rotor flow meter; 9. Aeration blower; 10. Piping; 11. Thermometer; 12. Dissolved oxygen meter; 13. ORP meter; 14. Sludge return pipeline; 15. Sludge return pump. Detailed Implementation

[0052] All references cited in this invention are incorporated herein by reference in their entirety, and in the event of any inconsistency between the meanings expressed in these references and those expressed herein, the meanings expressed herein shall prevail. Furthermore, the various terms and phrases used in this invention have their general meanings known to those skilled in the art; however, this invention still seeks to provide a more detailed explanation and interpretation of these terms and phrases, and in the event of any inconsistency between the mentioned terms and their known meanings and those expressed herein, the meanings expressed herein shall prevail.

[0053] When an item is described using the combined terms “...and / or ...", the description should be understood to include any one of the listed items and all combinations thereof.

[0054] Generally, the use of the term "about" indicates an approximation that can vary depending on the desired characteristics obtained from the disclosed subject matter and will be interpreted in a context-dependent manner based on function. Therefore, those skilled in the art will be able to interpret a degree of difference on a case-by-case basis. In some cases, the number of significant figures used when expressing a particular value can be a representative technique for determining the difference allowed by the term "about." In other cases, a gradient within a range of values ​​can be used to determine the range of differences allowed by the term "about." Furthermore, all ranges in this disclosure are inclusive and composable, and references to values ​​described within a range include every value within that range.

[0055] In this invention, the term "comprising" or "containing" indicates that various ingredients may be used together in the composition of this invention. Therefore, the terms "consistent with..." and "composed of..." are included in the term "comprising" or "containing".

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terms used herein and / or include any and all combinations of one or more of the associated listed items.

[0057] Unless otherwise stated, any feature disclosed in this specification may be replaced by other equivalent or similar features. Unless otherwise stated, each feature is merely one example of a series of equivalent or similar features. The descriptions are merely to aid in understanding the invention and should not be construed as limiting the invention. Unless otherwise specified, specific conditions in the embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0058] The present invention will be further described below with reference to specific embodiments.

[0059] Example 1

[0060] The schematic diagram of the apparatus used in the salt-tolerant activated sludge acclimatization method provided in this embodiment is shown below. Figure 1 As shown,

[0061] The acclimatization device comprises a split-type anaerobic-anoxic reactor 1 and an aerobic reactor 2. The upper parts of the anaerobic-anoxic reactor 1 and the aerobic reactor 2 are connected by a pipe 10, and the lower parts are connected by a sludge return pipe 14. Through the pipe 10 and the sludge return pipe 14, sludge circulation and return between the two reactors can be achieved, which helps maintain the system's biomass and treatment efficiency, especially in the face of water quality fluctuations. Both the anaerobic-anoxic reactor 1 and the aerobic reactor 2 have multiple sampling ports 5 on their side walls for convenient real-time sampling.

[0062] Both the anaerobic-anoxic reactor 1 and the aerobic reactor 2 are equipped with microporous aerators 4 at their bottom. The main function of the microporous aerators 4 is to introduce air into the reactor to provide sufficient dissolved oxygen for aerobic microorganisms to use, promoting the oxidative decomposition of organic matter. It introduces gas into the water through a microporous or small-pore structure, forming bubbles and thus increasing the oxygen content in the water. In addition, the microporous aerators also help prevent suspended matter in the mixing tank from settling and enhance the contact between organic matter, microorganisms, and dissolved oxygen. The microporous aerators 4 are connected to the aeration fan 9 via a rotor flow meter 8.

[0063] Both the anaerobic-anoxic reactor 1 and the aerobic reactor 2 are equipped with a thermometer 11, a dissolved oxygen meter 12, and an ORP meter 13, respectively. The thermometer 11 measures the temperature inside the reactor. The dissolved oxygen meter 12 monitors the dissolved oxygen (DO) level in the reactor. The ORP meter 13 (oxidation-reduction potentiometer) measures the oxidation-reduction potential in the reactor, a comprehensive indicator characterizing the relative degree of oxidative or reducing properties of the medium. Monitoring the ORP value helps to understand the dynamic balance of oxidation and reduction reactions in the reactor and is of guiding significance for controlling biochemical reactions such as nitrification and denitrification in the anaerobic-anoxic reactor.

[0064] The anaerobic-anoxic reactor 1 is also equipped with a fluidized bed packing 3. In this embodiment, the volume of the sulfurized fluidized bed packing 3 is 60% of the volume of the anaerobic-anoxic reactor 1. The aerobic reactor 2 is also equipped with a stirrer 7 for stirring and aeration.

[0065] In this embodiment, both the anaerobic-anoxic reactor 1 and the aerobic reactor 2 have a height of 1.5m, a diameter of 0.6m, and a total effective volume of 0.3m³. 3 The material is high-strength acrylic sheet. In practical applications, the invention objective of this application can be achieved when the height-to-diameter ratio of the anaerobic-anoxic reactor 1 and the aerobic reactor 2 is between 2.5 and 5.

[0066] The specific domestication methods are as follows:

[0067] Fresh sludge was introduced into the aforementioned acclimatization device. The fresh sludge was taken from the biochemical sludge thickening tank of a food processing plant's wastewater treatment station, with a sludge moisture content of 98%–99%; VSS / TSS ≥ 0.8 ± 0.1; and SVI 85–150. At this point, the initial salt concentration of the system was 0.5%, MLSS was 6000 mg / L, and CODcr was 3500 mg / L. After approximately 7 days of acclimatization, when the influent CODcr was 4500 mg / L (using glucose as the carbon source), the CODcr removal rate was approximately 95%, and the sludge settling performance was good.

[0068] At this point, the influent salinity is controlled at 3.5%, CODcr at 3500 mg / L, ammonia nitrogen at 100 mg / L, and total phosphorus at 25 mg / L. Salt content is achieved by adding sodium chloride and sodium sulfate, with the CODcr / SO4 ratio controlled to be ≤3. 2- The CODcr level is ≤10, where the CODcr is obtained by mixing biomedical wastewater carbon source (without recalcitrant organic matter) and added glucose carbon source at a ratio of 4:1. The parameters of the biomedical wastewater are: CODcr 6000–8000 mg / L, total nitrogen 70–100 mg / L, total phosphorus 10–15 mg / L, and salinity 2%. In this implementation, ammonia nitrogen is adjusted by adding urea, and total phosphorus is adjusted by adding potassium dihydrogen phosphate.

[0069] When the acclimatization process begins and a salinity of 3.5% is introduced into the acclimatization device, the CODcr removal rate drops to 30%. To address this, the following measures are taken: increasing the addition of external carbon, nitrogen, and phosphorus sources to the aerobic reactor to achieve a CODcr:N:P ratio of 100:5:1 to 150:5:1; increasing the aeration rate in the aerobic reactor to achieve dissolved oxygen levels of 5-6 mg / L; increasing the addition of external carbon, nitrogen, and phosphorus sources to the anaerobic reactor to achieve a CODcr:N:P ratio of 200:5:1 to 300:5:1; increasing the sludge return from the aerobic reactor to the anaerobic-anoxic reactor, with a return ratio controlled at 100%-200%; and supplementing with fresh external sludge based on the MLVSS / MLSS ratio. At the same time, the deactivated sludge is replaced, with the newly added sludge accounting for 1 / 5 to 1 / 3 and the discharged deactivated sludge accounting for 1 / 5 to 1 / 4, so that MLVSS / MLSS≥0.8. After about 10 to 15 days of adaptation, the CODcr removal rate increases to 75%.

[0070] The CODcr concentration was gradually increased, with each increase requiring an adaptation period of approximately 5-7 days. In this example, each increase in CODcr concentration was 1000 mg / L. The CODcr was obtained by mixing the carbon source from the biopharmaceutical wastewater with an added glucose carbon source at a ratio of 5:1. The higher the influent CODcr concentration, the longer the required acclimatization period. The oxidation-reduction potential in the anoxic reaction zone was controlled between -100 mV and +100 mV, and aeration was performed every 4 hours in the anaerobic-anoxic reaction zone. The oxidation-reduction potential in the aerobic reaction zone was controlled between +200 mV and +400 mV. When the sludge concentration reached ≥10000 mg / L, sludge was discharged, and the sludge concentration was kept stable.

[0071] Acclimated salt-tolerant activated sludge was used to treat biopharmaceutical wastewater with a salinity of 3%. Other parameters of this wastewater were: CODcr 9700 mg / L, total nitrogen 80 mg / L, and total phosphorus 8 mg / L. After adding the acclimated salt-tolerant activated sludge, on the 8th day of treatment, the influent CODcr was 2700 mg / L, and the CODcr removal rate stabilized at approximately 72.1%. The sludge's MLVSS was 5.1 g / L at the beginning of acclimation, and after a period of time, its value eventually stabilized at 7 g / L, indicating that the sludge gradually adapted to the high-salinity wastewater, and its volatile components increased significantly, with the concentration of volatile activated sludge (MLVSS) increasing by 37.3%.

[0072] Example 2

[0073] The salt-tolerant activated sludge acclimatization method provided in this embodiment uses the acclimatization equipment in Example 1, and the specific steps are as follows:

[0074] Fresh sludge, taken from the biochemical sludge thickening tank of a food processing plant's wastewater treatment station, was introduced into the aforementioned acclimatization device. The sludge had a moisture content of 98%–99%, a VSS / TSS ratio of ≥0.8±0.1, and a SVI of 85–150. At this point, the initial salt concentration of the system was 0.5%, the MLSS was 6000 mg / L, and the CODcr was 3500 mg / L. After approximately 10 days of acclimatization, when the influent CODcr was 5000 mg / L (using glucose as the carbon source), the CODcr removal rate was approximately 95%, and the sludge settling performance was good.

[0075] At this point, the influent salinity is controlled at 5%, CODcr at 3500 mg / L, ammonia nitrogen at 80 mg / L, and total phosphorus at 15 mg / L. Salt content is achieved by adding sodium chloride and sodium sulfate, with the CODcr / SO4 ratio controlled to be ≤3. 2- The CODcr level is ≤10, where the CODcr is obtained by mixing biomedical wastewater carbon source (without recalcitrant organic matter) and added glucose carbon source in a 4:1 ratio. The parameters of the biomedical wastewater are CODcr 6000-8000 mg / L, total nitrogen 70-100 mg / L, total phosphorus 10-15 mg / L, and salinity 2.5%. In this implementation, ammonia nitrogen is adjusted by adding urea, and total phosphorus is adjusted by adding potassium dihydrogen phosphate.

[0076] When the acclimatization process begins, and a 5% salinity is introduced into the acclimatization device, the CODcr removal rate drops to 30%. This is achieved by taking the following measures:

[0077] The aerobic reactor is supplemented with external carbon, nitrogen, and phosphorus sources to achieve a CODcr:N:P ratio of 100:5:1 to 150:5:1. The aeration rate is increased to achieve dissolved oxygen levels of 5-6 mg / L. Similarly, the anaerobic reactor is supplemented with external carbon, nitrogen, and phosphorus sources to achieve a CODcr:N:P ratio of 200:5:1 to 300:5:1. Sludge is returned from the aerobic reactor to the anaerobic-anoxic reactor at a return ratio of 100%-200%. Depending on the MLVSS / MLSS ratio, fresh sludge is added while deactivated sludge is replaced. The proportion of newly added sludge is 1 / 5 to 1 / 3, and the proportion of deactivated sludge discharged is 1 / 5 to 1 / 4, ensuring an MLVSS / MLSS ratio ≥ 0.8. After approximately 15-20 days of adaptation, the CODcr removal rate increases to 75%.

[0078] The CODcr concentration was gradually increased, with each increase requiring an adaptation period of approximately 5-7 days. In this example, each increase in CODcr concentration was 500 mg / L. The CODcr was obtained by mixing the carbon source from the biopharmaceutical wastewater with an added glucose carbon source at a ratio of 4:1. The higher the influent CODcr concentration, the longer the required acclimatization period. The oxidation-reduction potential in the anoxic reaction zone was controlled between -100 mV and +100 mV, and aeration was performed every 6 hours in the anaerobic-anoxic reaction zone. The oxidation-reduction potential in the aerobic reaction zone was controlled between +200 mV and +400 mV. When the sludge concentration reached ≥12000 mg / L, sludge was discharged, and the sludge concentration was kept stable.

[0079] At the end of the acclimation period, the influent CODcr was 10000 mg / L, and the CODcr removal rate stabilized at around 70.5%. The MLVSS of the sludge was 5.1 g / L at the beginning of acclimation, and after a period of acclimation, its value eventually stabilized at 8.4 g / L, indicating that the sludge gradually adapted to the high-salinity wastewater, and its volatile components increased significantly. From the initial stage of acclimation to the final stage of the experiment, the concentration of volatile activated sludge (MLVSS) increased by 64.7%, indicating that after a long period of acclimation, microorganisms can grow and reproduce in high-salinity wastewater. Although the direct acclimation method in a high-salinity environment initially subjected the sludge to a significant salinity shock, it ultimately resulted in activated sludge adapted to the high-salinity environment, and the acclimation time was relatively short, with an overall acclimation period of 80–90 days.

[0080] Example 3

[0081] In this embodiment, the salt-tolerant activated sludge obtained from the acclimation process in Example 2 was transferred to another chemical and pharmaceutical wastewater with a salinity of 5%. The parameters of this wastewater were CODcr 9500 mg / L, total nitrogen 60 mg / L, total phosphorus 5 mg / L, and salinity 5.1%. On the 12th day of treatment, the influent CODcr was 2800 mg / L, and the CODcr removal rate stabilized at around 70.5%. The MLVSS of the sludge was 7.2 g / L at the beginning of acclimation, and after a period of acclimation, its value eventually stabilized at 8.9 g / L, indicating that the sludge gradually adapted to the high-salinity wastewater, and its volatile components increased significantly. The concentration of volatile activated sludge (MLVSS) increased by 23.6%, indicating that the salt-tolerant activated sludge obtained in this application has strong adaptability to fluctuations in high-salinity wastewater.

[0082] Example 4

[0083] In this embodiment, the salt-tolerant activated sludge obtained from the domestication in Example 1 is transferred into fine chemical wastewater with a salinity of 4%. The parameters of the wastewater are CODcr 9600mg / L, total nitrogen 110mg / L, total phosphorus 30mg / L, and salinity 4%.

[0084] On the 15th day of treatment, the influent CODcr was 3100 mg / L, and the CODcr removal rate stabilized at around 67.7%. The MLVSS of the sludge was 7 g / L at the beginning of acclimation, and after a period of time, its value eventually stabilized at 8.5 g / L, indicating that the sludge gradually adapted to the high-salt wastewater, and its volatile components increased significantly. The concentration of volatile activated sludge (MLVSS) increased by 21.4%, indicating that the salt-tolerant activated sludge obtained in this application has good heritability.

[0085] Example 5

[0086] This embodiment is basically the same as Embodiment 1, except that approximately 0.01 kg / m³ is added to the aerobic reactor. 3 Powdered activated carbon promotes the coagulation of activated sludge.

[0087] On the 5th day of treatment, the influent CODcr was 2600 mg / L, and the CODcr removal rate stabilized at around 73.2%. The MLVSS of the sludge was 5.1 g / L at the beginning of acclimatization, and after a period of time, its value eventually stabilized at 7.2 g / L, indicating that the sludge gradually adapted to the high-salinity wastewater, and its volatile components increased significantly, with the concentration of volatile activated sludge (MLVSS) increasing by 41.2%.

[0088] Comparative Example 1

[0089] This comparative example is basically the same as Example 1, except that the concentration of acclimatized salt in the system is 7%.

[0090] In this comparative acclimatization method, due to excessively high salt concentration, a large number of activated sludge died. The MLVSS of the sludge was 4.8 g / L at the beginning of acclimatization, and then rapidly decreased to 1 g / L. Even after multiple replenishments of fresh sludge, the concentration of volatile activated sludge (MLVSS) remained below 1.2 g / L, and the CODcr removal rate was below 15%, indicating that it is difficult to cultivate activated sludge with high salt concentration.

[0091] Comparative Example 2

[0092] This comparative example is basically the same as Example 1, except that the CODcr concentration gradient is gradually increased in increments of 2000 mg / L.

[0093] In this comparative acclimatization method, due to the excessively high gradient, when CODcr increased from the initial 3500 mg / L to 5500 mg / L, the MLVSS of the sludge decreased from 5.1 g / L to 4.8 g / L. Subsequently, by increasing nutrient supplementation, adding fresh sludge, removing deactivated sludge, and optimizing acclimatization conditions, the MLVSS of the sludge increased to 5.4 g / L, the CODcr removal rate reached 75%, and the adaptation period was extended to more than 20 days. When CODcr increased from 5500 mg / L to 7500 mg / L, the MLVSS of the sludge decreased again to 4 g / L. Subsequently, by increasing nutrient supplementation, adding fresh sludge, removing deactivated sludge, and optimizing acclimatization conditions, it recovered to 5 g / L, the CODcr removal rate reached 65%, and the adaptation period was about 25 days. This indicates that sludge is more sensitive to large fluctuations in CODcr under high salinity environments, the sludge adaptation period is increased, and sludge proliferation is constrained by both high salinity and high CODcr, thus increasing the difficulty of sludge acclimatization.

Claims

1. A method for acclimating salt-tolerant activated sludge, characterized in that: Including the following steps: S1. Fresh sludge is introduced into the acclimatization device. The fresh sludge has a moisture content of 98%~99%, VSS / TSS≥0.8±0.1, and SVI of 85~150. The acclimatization device includes an anaerobic-anoxic reaction zone and an aerobic reaction zone that are interconnected. At the beginning of acclimatization, the sludge concentration MLSS is controlled at 5000~6000 mg / L. S2. Control the salt concentration in the system to be 3-5%, and control 3 ≤ CODcr / SO4. 2- ≤10, when the CODcr removal rate is ≤30%, through Nutrients are added to the acclimatization device to make the proportion of external carbon source reach 1 / 4 to 1 / 5. The added nutrients consist of wastewater carbon source and glucose in a mass ratio of 4:1 to 5:1; CODcr:N:P is 100:5:1 to 300:5:1; the wastewater carbon source is a biopharmaceutical wastewater carbon source that does not contain degradable organic matter; and / or, Increase the aeration rate in the aerobic reaction zone to achieve a dissolved oxygen level of 5-6 mg / L; and / or, Sludge from the aerobic reaction zone is returned to the anaerobic-anoxic reaction zone, with the return ratio controlled at 100%~200%; and / or, Replenish with fresh sludge, with the newly added sludge accounting for 1 / 5 to 1 / 3 of the total sludge volume; and / or, The amount of deactivated sludge discharged externally accounts for 1 / 5 to 1 / 4 of the total amount of sludge discharged externally, until the CODcr removal rate is ≥75%; S3. Gradually increase the CODcr concentration gradient in increments of 500-1000 mg / L, with an acclimatization period of 5-10 days for each CODcr concentration gradient; control the sludge age to 20-25 days; when the sludge concentration is ≥10000-12000 mg / L, discharge the sludge and control the sludge concentration to remain stable. The acclimation process was terminated when the influent CODcr ≥ 10000 mg / L and the removal rate ≥ 70%, thus obtaining the salt-tolerant activated sludge.

2. The method for acclimating salt-tolerant activated sludge according to claim 1, characterized in that: The method used to control the salt concentration in the system is by adding salts; the salts are sodium chloride and sodium sulfate.

3. The method for acclimatizing salt-tolerant activated sludge according to claim 1, characterized in that: The fresh sludge was taken from the biochemical sludge thickening tank of the wastewater treatment plant in the food processing plant.

4. The method for acclimatizing salt-tolerant activated sludge according to claim 1, characterized in that: The oxidation-reduction potential of the hypoxic reaction zone is controlled between -100 mV and +100 mV; the oxidation-reduction potential of the aerobic reaction zone is controlled between +200 mV and +400 mV.

5. The method for acclimatizing salt-tolerant activated sludge according to claim 1, characterized in that: The anaerobic-hypoxic reaction zone is aerated once every 4 to 6 hours.

6. The method for acclimating salt-tolerant activated sludge according to any one of claims 1-5, characterized in that: Flocculant is added to the aerobic reaction zone.

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