Culture method of salt-tolerant aerobic granular sludge and degradation method of industrial wastewater

Abstract

The invention relates to the technical field of environmental biotechnology and wastewater treatment, in particular to a culture method of salt-tolerant aerobic granular sludge and a degradation method of industrial wastewater, the culture method comprises the following steps: S1, inoculating initial aerobic granular sludge into a bioreactor; and S2, preliminarily adding acrylamide and an auxiliary carbon source into the bioreactor obtained in the step S1, and then increasing the acrylamide and reducing the addition amount of the auxiliary carbon source for domestication to obtain the salt-tolerant aerobic granular sludge. The salt-tolerant aerobic granular sludge cultured by the invention can grow and metabolize in an environment in which the sodium chloride concentration is not less than 10g / L by taking acrylamide as a unique carbon source, so that the salt-tolerant aerobic granular sludge has excellent salt tolerance and efficient acrylamide degradation capacity, and can degrade more than 95% of 200mg / L acrylamide within 6 hours; meanwhile, the salt-tolerant aerobic granular sludge is regular in particle shape, compact in structure and good in settling performance (the SVI (sludge index) value is only 24.0 mL / g).

Description

Technical Field

[0001] This disclosure relates to the fields of environmental biotechnology and wastewater treatment technology, and in particular to methods for cultivating salt-tolerant aerobic granular sludge and methods for degrading industrial wastewater. Background Technology

[0002] Acrylamide (AM) is a water-soluble vinyl monomer widely used in various industrial sectors, including oil extraction, papermaking, and mining, as a crucial raw material for the production of polyacrylamide. However, acrylamide is a known neurotoxic, genotoxic, and carcinogenic substance that poses a serious threat to the ecological environment and human health. The production and use of polyacrylamide inevitably generate industrial wastewater containing residual acrylamide monomers. This is particularly true in industries such as chemical engineering and oil and gas extraction (e.g., polymer flooding), where wastewater not only contains high concentrations of acrylamide but also typically exhibits extremely high salinity (sodium chloride concentrations can reach 10-30 g / L). Acrylamide's high water solubility makes it highly susceptible to migration and diffusion in water bodies, causing persistent pollution of surface and groundwater.

[0003] Currently, the main technologies for treating acrylamide-containing wastewater include physicochemical and biological methods. While physicochemical methods (such as adsorption and advanced oxidation) can effectively remove acrylamide, they suffer from high costs and the potential for secondary pollution. Biological methods, due to their low cost and environmental friendliness, are considered the most promising treatment technology. Studies have shown that some microorganisms can utilize acrylamide as a carbon or nitrogen source for metabolism. Their degradation pathway primarily involves the hydrolysis of acrylamide into acrylic acid and ammonia via amidase, which are then utilized by the microorganisms. However, the traditional activated sludge process faces significant challenges in treating this type of wastewater: firstly, acrylamide has a strong toxic and inhibitory effect on common microorganisms; secondly, the prevalent high salinity environment in the wastewater generates strong osmotic pressure stress, leading to microbial cell dehydration, reduced enzyme activity, and even death, resulting in low efficiency, unstable operation, and even collapse of the entire biological treatment system.

[0004] Aerobic granular sludge (AGS) technology is a novel biological wastewater treatment technology that has emerged in recent years. AGS consists of dense, granular bioaggregates formed by the self-aggregation of microorganisms under specific hydraulic conditions. Compared to traditional flocculent activated sludge, AGS offers advantages such as dense structure, good settling performance, high biomass, strong resistance to shock loads, and the ability to simultaneously perform nitrification and denitrification. It is considered an ideal choice for treating high-concentration, toxic, and recalcitrant industrial wastewater.

[0005] Existing studies have attempted to use aerobic sludge (AGS) to treat high-salinity wastewater, but the cultivation process typically requires months of salinity gradient acclimatization, a lengthy and unstable process. Furthermore, current research on salt-tolerant AGS primarily focuses on the removal of conventional organic matter, failing to specifically address the degradation of specific toxic pollutants like acrylamide, and lacks dedicated microbial community cultivation techniques capable of simultaneously tolerating high salinity and efficiently degrading acrylamide. Moreover, research on the degradation of acrylamide by salt-tolerant aerobic granular sludge is limited, and dedicated microbial community cultivation techniques capable of simultaneously tolerating high salinity and efficiently degrading acrylamide are also lacking.

[0006] Therefore, there is an urgent need to develop an aerobic granular sludge that can simultaneously tolerate high salt and acrylamide toxicity and efficiently degrade acrylamide, as well as a rapid cultivation method thereof, to solve the problem of treating saline and acrylamide-containing industrial wastewater. Summary of the Invention

[0007] The technical problem solved by this disclosure is to provide a method for cultivating salt-tolerant aerobic granular sludge. The salt-tolerant aerobic granular sludge cultivated by this disclosure is an aerobic granular sludge with salt tolerance and acrylamide degradation function, which can achieve high treatment efficiency, high stability and short cycle degradation of industrial wastewater with high salt and high concentration of acrylamide.

[0008] In view of this, this application provides a method for cultivating salt-tolerant aerobic granular sludge, comprising the following steps:

[0009] S1. Inoculate the initial aerobic granular sludge into the bioreactor;

[0010] The initial aerobic granular sludge is an aerobic granular sludge that is tolerant to sodium chloride concentrations of ≥10 g / L.

[0011] S2. Acrylamide and auxiliary carbon source are initially added to the bioreactor obtained in step S1. Then, the amount of acrylamide added is gradually increased and the amount of auxiliary carbon source added is decreased to acclimate the initial aerobic granular sludge until the acrylamide concentration in the effluent of the bioreactor is stably lower than 10 mg / L, and salt-tolerant aerobic granular sludge is obtained.

[0012] During the acclimatization process, the acrylamide is added by increasing the amount of acrylamide by 20-25 mg / L every 7 days until the concentration of acrylamide in the culture medium is 180-220 mg / L. The auxiliary carbon source is added by decreasing the amount of auxiliary carbon source by 80-120 mg / L every 7 days until the amount is 0, compared to the initial concentration of the initially added auxiliary carbon source.

[0013] In some specific embodiments, in step S2, the initial addition of acrylamide and auxiliary carbon source lasts for 14 to 16 days, based on a culture medium composed of acrylamide and auxiliary carbon source. The amount of acrylamide added to the bioreactor is 8 to 15 mg / L / day, and the amount of auxiliary carbon source added to the bioreactor is 500 to 1000 mg / L / day.

[0014] In some specific embodiments, in step S2, the auxiliary carbon source includes one or more of glucose, sodium acetate, and methanol.

[0015] In some specific embodiments, the initial aerobic granular sludge has a sludge concentration index of 20~60mL / g and a particle size of 0.5~1.0mm.

[0016] In some specific embodiments, in step S1, the suspended solids concentration of the initial aerobic granular sludge is 3000~6000 mg / L.

[0017] In some specific embodiments, the bioreactor is a sequencing batch reactor (SBR), which includes sequentially occurring influent, anaerobic, aerobic, sedimentation, and effluent phases; wherein the influent phase lasts 5-15 minutes, the anaerobic phase lasts 20-40 minutes, the aerobic phase lasts 240-320 minutes, the sedimentation phase lasts 15-40 minutes, and the effluent phase lasts 5-15 minutes.

[0018] In some specific embodiments, the culture time of the culture method is 130 to 160 days.

[0019] This application provides a method for degrading acrylamide in industrial wastewater, comprising:

[0020] Industrial wastewater and salt-tolerant aerobic granular sludge are mixed for degradation;

[0021] The salt-tolerant aerobic granular sludge is the salt-tolerant aerobic granular sludge cultivated by the cultivation method described in the above scheme.

[0022] In some specific embodiments, the industrial wastewater originates from the polyacrylamide production industry, the tertiary oil recovery industry, or the papermaking industry; and / or, the concentration of sodium chloride in the industrial wastewater is 10~30g / L, and the concentration of acrylamide is 100~300mg / L.

[0023] In some specific embodiments, the degradation temperature is 20~30℃ and the degradation time is 5~8h.

[0024] This disclosure provides a method for cultivating aerobic granular sludge with salt tolerance and acrylamide degradation function. First, initial aerobic granular sludge is inoculated into a bioreactor. Then, acrylamide and an auxiliary carbon source are initially added to the bioreactor. Next, acrylamide is gradually added to the bioreactor while the amount of auxiliary carbon source is reduced to acclimate the initial aerobic granular sludge until the acrylamide concentration in the effluent of the culture system is stably below 10 mg / L, thus obtaining aerobic granular sludge with salt tolerance and acrylamide degradation function. In the cultivation method of salt-tolerant aerobic granular sludge, this disclosure uses long-term salt-tolerant aerobic granular sludge as inoculum, and then gradually adds acrylamide and an auxiliary carbon source as carbon and nitrogen sources to reduce the toxic shock load on the aerobic granular sludge. This successfully induces the aerobic granular sludge to secrete a large amount of extracellular polymers to resist toxicity and promotes the formation of large-diameter particles. Microorganisms with acrylamide degradation function are gradually screened out, ultimately obtaining aerobic granular sludge with salt tolerance and acrylamide degradation function.

[0025] This disclosure also provides a method for degrading acrylamide in industrial wastewater, which uses the salt-tolerant aerobic granular sludge cultivated above to degrade the industrial wastewater. Since the salt-tolerant aerobic granular sludge has salt tolerance and acrylamide degradation function, it can quickly and stably achieve the degradation of acrylamide in industrial wastewater. Attached Figure Description

[0026] Figure 1 The graph shows the changes in the concentration of suspended organic solids (VSS), MLSS, and SVI in the mixed liquor during the aerobic granular sludge acclimatization and cultivation process in the example; where the horizontal axis represents time (days), the vertical axis (left) represents MLSS / VSS (g / L), and the vertical axis (right) represents SVI (mL / g).

[0027] Figure 2 This is a graph showing the change in sludge particle size during the aerobic granular sludge acclimatization and cultivation process in the example; where the horizontal axis represents time (days) and the vertical axis represents the sludge particle size distribution (%).

[0028] Figure 3 The graph shows the change in EPS secretion during the aerobic granular sludge acclimatization and cultivation process in the example; where the horizontal axis represents time (days) and the vertical axis represents the secretion amount of each EPS component (mg / L).

[0029] Figure 4 The graph shown in the example is a curve of continuous monitoring of the degradation performance of mature granular sludge on salt-containing acrylamide wastewater; where the horizontal axis is time (days), the vertical axis (left) is the acrylamide concentration in the effluent (g / L), and the vertical axis (right) is the removal rate (%). Detailed Implementation

[0030] To further understand this disclosure, preferred embodiments of this disclosure are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of this disclosure and are not intended to limit the scope of the claims of this disclosure.

[0031] In view of the existing technology's need for aerobic granular sludge that is resistant to high salt and acrylamide toxicity and can efficiently degrade acrylamide, in order to solve the problem of degradation of saline acrylamide industrial wastewater, this disclosure provides a method for cultivating salt-tolerant aerobic granular sludge. The method uses a culture system in which an auxiliary carbon source and acrylamide coexist for initiation and acclimatization cultivation. By gradually increasing the acrylamide concentration while simultaneously decreasing the auxiliary carbon source concentration, a large amount of extracellular polymers are successfully induced in the aerobic granular sludge to resist acrylamide toxicity, and the formation of large-diameter particles is promoted. This results in aerobic granular sludge that is resistant to high salt and acrylamide toxicity and can efficiently degrade acrylamide. Specifically, this disclosure provides a method for cultivating salt-tolerant aerobic granular sludge, including the following steps:

[0032] S1. Inoculate the initial aerobic granular sludge into the bioreactor;

[0033] The initial aerobic granular sludge is an aerobic granular sludge that is tolerant to sodium chloride concentrations of ≥10 g / L.

[0034] S2. Acrylamide and auxiliary carbon source are initially added to the bioreactor obtained in step S1. Then, the amount of acrylamide added is gradually increased and the amount of auxiliary carbon source added is decreased to acclimate the initial aerobic granular sludge until the acrylamide concentration in the effluent of the bioreactor is stably lower than 10 mg / L, and salt-tolerant aerobic granular sludge is obtained.

[0035] During the acclimatization process, the acrylamide is added by increasing the amount of acrylamide by 20-25 mg / L every 7 days until the concentration of acrylamide in the culture medium is 180-220 mg / L. The auxiliary carbon source is added by decreasing the amount of auxiliary carbon source by 80-120 mg / L every 7 days until the amount is 0, compared to the initial concentration of the initially added auxiliary carbon source.

[0036] In the method for cultivating salt-tolerant aerobic granular sludge, in step S1, initial aerobic granular sludge is first inoculated into a bioreactor. In this step, the initial aerobic granular sludge is aerobic granular sludge that can tolerate ≥10 g / L of sodium chloride. Specifically, the initial aerobic granular sludge is aerobic granular sludge with the ability to tolerate 10 g / L NaCl for a long period of time. Further, the sludge concentration index of the initial aerobic granular sludge is 20~60 mL / g, and the particle size is 0.5~1.0 mm. In some specific embodiments, the sludge concentration index of the initial aerobic granular sludge is 30~50 mL / g, and the particle size is 0.6~0.8 mm.

[0037] In this disclosure, the bioreactor is a sequencing batch reactor (SBR). The operation of the SBR includes a sequential influent phase, an anaerobic phase, an aerobic phase, a sedimentation phase, and an effluent phase. The influent phase lasts 5-15 minutes, the anaerobic phase lasts 20-40 minutes, the aerobic phase lasts 240-320 minutes, the sedimentation phase lasts 15-40 minutes, and the effluent phase lasts 5-15 minutes. This constitutes one operating cycle of the SBR. The influent phase allows wastewater containing high concentrations of salt and acrylamide to gradually enter, thereby reducing the toxic shock load on the aerobic granular sludge. Specifically, the influent phase lasts 8-10 minutes. The anaerobic phase facilitates the full penetration and diffusion of the culture medium into the aerobic granular sludge. Specifically, the anaerobic phase lasts 25-30 minutes. Since this disclosure cultivates aerobic granular sludge, the aerobic phase is a critical period, lasting 240-320 minutes to provide the conditions required for complete acrylamide degradation. If the time is too short, degradation will be incomplete. If the aerobic period is too long, it can easily lead to excessive endogenous respiration of the sludge and its disintegration. Specifically, the aerobic period is 260-300 minutes. The sedimentation period is designed to ensure that all the supernatant is discharged during effluent. The above time limits can both complete sedimentation and achieve sludge-water separation, and effectively select and eliminate ordinary sludge with poor settling properties. If it is too long, granular screening cannot be achieved; if it is too short, high-quality particles will be lost. Specifically, the sedimentation period is 20-30 minutes. The effluent period is for discharging the supernatant. Specifically, the effluent period is 8-10 minutes. The above influent period, anaerobic period, aerobic period, sedimentation period, and effluent period constitute a cycle.

[0038] In step S2, acrylamide and an auxiliary carbon source are initially added to the bioreactor obtained in step S1. The amount of acrylamide added is then gradually increased while the amount of auxiliary carbon source is decreased to acclimate the initial aerobic granular sludge until the acrylamide concentration in the bioreactor effluent is stably below 10 mg / L, resulting in salt-tolerant aerobic granular sludge with acrylamide degradation function. During this process, a culture medium, including acrylamide and an auxiliary carbon source, is first introduced into the sequencing batch bioreactor (SBR) inoculated with the initial aerobic granular sludge. As described above, the introduction of the culture medium into the SBR includes sequential influent, anaerobic, aerobic, sedimentation, and effluent phases, constituting one cycle of the culture medium entering the bioreactor. The initial addition of acrylamide and auxiliary carbon source lasts for 14-16 days, specifically 15 days. During this time, the culture medium is continuously introduced into the bioreactor, using a culture medium composed of acrylamide and auxiliary carbon source as the base. The amount of acrylamide added is 8-15 mg / L / day, and the amount of auxiliary carbon source added is 5 mg / L / day. The concentration of acrylamide is 00~1000 mg / L / day, meaning that during the aforementioned duration, the daily addition of acrylamide is 8~15 mg / L, and the daily addition of the auxiliary carbon source is 500~1000 mg / L. In some specific embodiments, the daily addition of acrylamide is 10~12 mg / L, and the daily addition of the auxiliary carbon source is 700~800 mg / L. The above concentration of acrylamide is used to adapt the initial aerobic granular sludge to the presence of acrylamide and to gradually screen out microorganisms with preliminary degradation capabilities. In this disclosure, the auxiliary carbon source includes one or more of glucose, sodium acetate, and methanol; in some specific embodiments, the auxiliary carbon source is selected from glucose.

[0039] In some specific embodiments, the initial addition of acrylamide and auxiliary carbon source continues for 15 days. In a sequencing batch bioreactor, with a cycle of 6 hours, 60 cycles are performed over 15 days. During this period, the concentration of acrylamide is controlled at 8-15 mg / L, and the concentration of auxiliary carbon source is controlled at 500-1000 mg / L.

[0040] In step S2, acrylamide is gradually added to the bioreactor while the amount of auxiliary carbon source is reduced to acclimate the aerobic granular sludge until the acrylamide concentration in the bioreactor effluent is stably below 10 mg / L, thus obtaining salt-tolerant aerobic granular sludge. During this process, the acrylamide is added in the following manner: compared to the initial acrylamide concentration, the amount of acrylamide added is increased by 20-25 mg / L every 7 days until the acrylamide concentration in the culture medium is 180-220 mg / L. The auxiliary carbon source is added in the following manner: compared to the initial auxiliary carbon source concentration... The initial concentration of the carbon source is reduced by 80-120 mg / L every 7 days until the amount added is zero. In some specific embodiments, the acrylamide is added by increasing the amount added by 21-23 mg / L every 7 days compared to the initial concentration of acrylamide until the concentration of acrylamide in the culture medium is 190-200 mg / L. The auxiliary carbon source is added by reducing the amount added by 90-110 mg / L every 7 days until the amount added is zero. The specific method for adding acrylamide and auxiliary carbon source is as follows: Compared to the initial concentration of acrylamide, the weekly addition amount is increased by 20-25 mg / L every 7 days until the acrylamide concentration in the culture medium reaches 180-220 mg / L. Conversely, the weekly addition amount of auxiliary carbon source is decreased by 80-120 mg / L every 7 days until it reaches zero. This reverse gradient dynamic regulation of increasing acrylamide addition and decreasing auxiliary carbon source addition successfully induced the sludge to secrete large amounts of extracellular polymers to resist toxicity and promoted the formation of large-diameter particles, which is beneficial for improving the salt tolerance of salt-tolerant aerobic granular sludge and its acrylamide degradation performance.

[0041] In this disclosure, the initial aerobic granular sludge cultivation time is 130-160 days, specifically 142-150 days. In some specific embodiments, the cultivation time is 142 days. Days 1-15 are the initial stage, during which the aerobic granular sludge and culture medium are mixed while maintaining a constant acrylamide concentration in the medium. From day 16 onwards, the acclimatization stage begins, with the amount of acrylamide continuously increasing while the amount of auxiliary carbon source continuously decreasing until the acrylamide concentration stabilizes at 180-220 mg / L. Afterwards, the addition of acrylamide and auxiliary carbon source is stopped, and the cultivation enters the stable period. The salt-tolerant aerobic granular sludge cultivation method provided in this disclosure significantly shortens the cultivation cycle.

[0042] This application also provides a method for degrading acrylamide in industrial wastewater, including:

[0043] Industrial wastewater and salt-tolerant aerobic granular sludge are mixed for degradation;

[0044] The salt-tolerant aerobic granular sludge is the salt-tolerant aerobic granular sludge cultivated by the above-mentioned cultivation method.

[0045] In this disclosure, the industrial wastewater originates from the polyacrylamide production industry, the tertiary oil recovery industry, or the papermaking industry. The concentration of sodium chloride in the wastewater is 10-30 g / L, and the concentration of acrylamide is 100-300 mg / L. In a specific embodiment, the concentration of sodium chloride in the wastewater is 15-20 g / L, and the concentration of acrylamide is 200-250 mg / L. The degradation temperature is 20-30°C, and the degradation time is 5-8 hours. Specifically, the degradation temperature is 25-28°C, and the degradation time is 6-7 hours.

[0046] To further understand this disclosure, the application of the salt-tolerant aerobic granular sludge cultivation method provided in this disclosure will be described in detail below with reference to the embodiments. The scope of protection of this disclosure is not limited to the following embodiments.

[0047] Example 1: Cultivation of aerobic granular sludge with salt-resistant acrylamide degradation function

[0048] (1) Construction and operating parameters of SBR reactor

[0049] A cylindrical acrylic sequencing batch reactor (SBR) with an effective volume of 1.2 L, an inner diameter of 6.18 cm, and a height-to-diameter ratio of approximately 8.1 is adopted. The reactor is equipped with a water bath jacket, and the reactor temperature is controlled at (25±1)℃ through a constant temperature water bath. An aeration sand head is installed at the bottom of the reactor, which is connected to an air compressor to provide oxygen. The aeration rate is controlled at 150 L / h to ensure that the dissolved oxygen concentration is 2~4 mg / L and to provide sufficient shear force. The inlet and outlet are controlled by a peristaltic pump and a solenoid valve, respectively. The entire operation cycle is automatically controlled by a programmable logic controller (PLC).

[0050] (2) Inoculation with sludge and simulated wastewater

[0051] The inoculated sludge was derived from aerobic granular sludge from a wastewater treatment plant that treats high-salt chemical wastewater. This sludge has been able to withstand 10 g / L sodium chloride for a long time, is grayish-black in color, and has a particle size mainly distributed between 0 and 100 μm. The SVI is 60 mL / g. After inoculation, the initial mixed liquor suspended solids concentration (MLSS) in the reactor was about 4000 mg / L. This sludge has no obvious ability to degrade acrylamide.

[0052] The simulated wastewater components include: acrylamide (concentration adjusted according to different stages), C6H 12O6 (concentration adjusted according to different stages), NaCl 10 g / L, K2HPO4 0.2 g / L, KH2PO4 0.1 g / L, MgSO4·7H2O 0.1 g / L, and a 1 mL / L trace element solution; the trace element solution composition is: EDTA 0.5 g / L, FeSO4·7H2O 0.2 g / L, ZnSO4·7H2O 0.01 g / L, MnCl2·4H2O 0.003 g / L, H3BO3 0.03 g / L, CoCl2·6H2O 0.02 g / L, CuCl2·2H2O 0.001 g / L, NiCl2·6H2O 0.002 g / L, Na2MoO4·2H2O 0.003 g / L;

[0053] (3) Domestication and cultivation process

[0054] The entire cultivation process is divided into three stages, totaling 142 days:

[0055] Phase 1: Adaptation Period (Days 1-15)

[0056] The SBR operating cycle was set to 6 hours (influent (10 min), anaerobic period (30 min), aerobic period (280 min), sedimentation period (30 min), and effluent (10 min)). Aerobic granular sludge was inoculated into the SBR, and then a culture medium composed of acrylamide and glucose was added to the SBR. The concentration of acrylamide was 10 mg / L and the concentration of glucose was 700 mg / L. Acrylamide and glucose were continuously introduced into the SBR at the above dosage for 15 days. This stage was intended to allow the inoculated sludge to adapt to the presence of acrylamide and to screen out microorganisms with preliminary degradation capabilities.

[0057] Phase Two: Acclimatization and Granulation Enhancement Period (Days 16-90)

[0058] This stage enhances the degradation performance and granulation characteristics of the sludge by applying selective pressure. The specific operation is as follows:

[0059] Acrylamide concentration: Starting from day 16, increase the influent acrylamide concentration by 20-25 mg / L per week (compared to the acrylamide concentration of the previous 15 days). Glucose concentration: Starting from day 16, decrease the influent glucose concentration by 100 mg / L per week (compared to the glucose concentration of the previous 15 days). By day 90, the effluent indicators were stable and the reactor was operating normally under the condition of 100 mg / L acrylamide.

[0060] Phase 3: Maturity and Stability Period (Days 91-142)

[0061] The influent acrylamide concentration was increased and stabilized at 200 mg / L. Under this condition, the system was operated continuously for 20 days until the effluent acrylamide concentration was stably lower than 10 mg / L and the various sludge performance indicators tended to stabilize. This marked the maturity of the cultivation of aerobic granular sludge with salt-tolerant acrylamide degradation function.

[0062] (4) Performance characterization of mature granular sludge

[0063] After 142 days of cultivation, samples were taken for analysis of the physicochemical properties of the mature granular sludge: the sludge was yellowish-brown in appearance, with regular particle shape and a smooth surface. Figure 1 As shown, throughout the entire cultivation process, the SVI value of the sludge continuously decreased from the initial 60 mL / g, stabilizing at around 30 mL / g on day 142, indicating a significant optimization of sludge settling performance. Simultaneously, the concentrations of MLSS and VSS steadily increased from 4200 mg / L and 3400 mg / L to 8500 mg / L and 7200 mg / L, respectively, indicating that the dominant bacterial community was effectively enriched and the biomass increased significantly.

[0064] In addition, such as Figure 2 As shown, under continuous acrylamide stress, the sludge particle size exhibited a significant increasing trend. In the initial stage, the sludge was in a fine state, with the 0-100 μm particle size component dominating (80.82%), while the large particle size component of 200-500 μm accounted for only 4.79%. After 142 days of continuous stress, the sludge particle size distribution shifted significantly: the proportion of the 0-100 μm component decreased to 27.37%, the 200-500 μm component jumped to become the main particle size range (34.59%), and coarse particles of 500-2000 μm appeared (1.63%).

[0065] like Figure 3 As shown, as a defense mechanism against environmental stress, the secretion of extracellular polymeric substances (EPS) increases synchronously with the intensification of AM stress; compared with the initial stage, the EPS secretion at 142 days increased by 40.5%.

[0066] Example 2: Degradation performance test of aerobic granular sludge cultured in this example on saline acrylamide wastewater.

[0067] (1) Experimental conditions

[0068] The mature aerobic granular sludge cultivated in Example 1 was used to test the degradation performance in the original SBR reactor. The SBR operation cycle was set to 6 hours, specifically: influent (10 min), anaerobic period (30 min), aerobic period (280 min), sedimentation period (30 min), and effluent (10 min). Simulated wastewater containing 10 g / L NaCl and 200 mg / L acrylamide was prepared as influent. After the reactor was influent, it was mixed with aerobic granular sludge. The initial concentration of acrylamide in the mixture was about 200 mg / L, and the reaction temperature was maintained at (25±1)℃.

[0069] (2) Sampling and analysis

[0070] The reactor effluent was collected for several consecutive days. After the samples were filtered through a 0.45 μm filter membrane, the concentration of acrylamide in the filtrate was determined.

[0071] (3) Results and Analysis

[0072] The degradation curve of acrylamide concentration over time is as follows: Figure 4 As shown, by Figure 4 It is evident that the mature aerobic granular sludge cultivated in this disclosure exhibits excellent degradation performance; under high salinity conditions of 10 g / L NaCl, the acrylamide concentration in the reactor decreased from an initial 200 mg / L to below 10 mg / L within 6 hours of aeration, achieving a removal rate of over 95%; this indicates that this disclosure has successfully achieved rapid and complete biodegradation of acrylamide under high salinity conditions, and can be effectively applied to the treatment of related industrial wastewater.

[0073] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of this disclosure. It should be noted that those skilled in the art can make several improvements and modifications to this disclosure without departing from the principles of this disclosure, and these improvements and modifications also fall within the protection scope of the claims of this disclosure.

[0074] The above description of the disclosed embodiments enables those skilled in the art to make or use this disclosure. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for cultivating salt-tolerant aerobic granular sludge, characterized in that, Includes the following steps: S1. Inoculate the initial aerobic granular sludge into the bioreactor; The initial aerobic granular sludge is an aerobic granular sludge that is tolerant to sodium chloride concentrations of ≥10 g / L. S2. Acrylamide and auxiliary carbon source are initially added to the bioreactor obtained in step S1. Then, the amount of acrylamide added is gradually increased and the amount of auxiliary carbon source added is decreased to acclimate the initial aerobic granular sludge until the acrylamide concentration in the effluent of the bioreactor is stably lower than 10 mg / L, and salt-tolerant aerobic granular sludge is obtained. During the acclimatization process, the acrylamide is added by increasing the amount of acrylamide by 20-25 mg / L every 7 days until the concentration of acrylamide in the culture medium is 180-220 mg / L. The auxiliary carbon source is added by decreasing the amount of auxiliary carbon source by 80-120 mg / L every 7 days until the amount is 0, compared to the initial concentration of the initially added auxiliary carbon source.

2. The cultivation method according to claim 1, characterized in that, In step S2, the initial addition of acrylamide and auxiliary carbon source lasts for 14 to 16 days. Based on the culture medium composed of acrylamide and auxiliary carbon source, the amount of acrylamide added to the bioreactor is 8 to 15 mg / L / day, and the amount of auxiliary carbon source added to the bioreactor is 500 to 1000 mg / L / day.

3. The cultivation method according to claim 1 or 2, characterized in that, In step S2, the auxiliary carbon source includes one or more of glucose, sodium acetate, and methanol.

4. The cultivation method according to claim 1, characterized in that, The initial aerobic granular sludge has a sludge concentration index of 20~60mL / g and a particle size of 0.5~1.0mm.

5. The cultivation method according to claim 1 or 4, characterized in that, In step S1, the initial suspended solids concentration of the aerobic granular sludge is 3000~6000 mg / L.

6. The cultivation method according to claim 1, characterized in that, The bioreactor is a sequencing batch reactor (SBR), which includes sequentially occurring influent, anaerobic, aerobic, sedimentation, and effluent phases. The influent phase lasts 5-15 minutes, the anaerobic phase lasts 20-40 minutes, the aerobic phase lasts 240-320 minutes, the sedimentation phase lasts 15-40 minutes, and the effluent phase lasts 5-15 minutes.

7. The cultivation method according to claim 1, characterized in that, The culture time for the culture method is 130 to 160 days.

8. A method for degrading acrylamide in industrial wastewater, comprising: Industrial wastewater and salt-tolerant aerobic granular sludge are mixed for degradation; The salt-tolerant aerobic granular sludge is the salt-tolerant aerobic granular sludge cultivated by the cultivation method described in any one of claims 1 to 7.

9. The degradation method according to claim 8, characterized in that, The industrial wastewater originates from the polyacrylamide production industry, the tertiary oil recovery industry, or the papermaking industry; and / or, the concentration of sodium chloride in the industrial wastewater is 10~30g / L, and the concentration of acrylamide is 100~300mg / L.

10. The degradation method according to claim 8, characterized in that, The degradation temperature is 20~30℃, and the degradation time is 5~8h.

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