CN114890537A - Filamentous sludge bulking control method based on quorum sensing - Google Patents

Abstract

The invention discloses a filamentous sludge bulking control method based on quorum sensing. Belongs to the technical field of filamentous sludge bulking control. The method comprises the steps of operating an activated sludge reactor, collecting an activated sludge sample, judging the sludge bulking degree and the sludge bulking type, performing gram staining and Neisseria staining, identifying the dominant filamentous bacteria causing filamentous sludge bulking, determining the types and the contents of N-Acylated Homoserine Lactone (AHLs) signal molecules, performing correlation analysis to determine the AHLs signal molecules which are negatively correlated with the filamentous sludge bulking, and adding the determined AHLs signal molecules into the activated sludge reactor, thereby realizing the control of the filamentous sludge bulking in the activated sludge reactor. The method is simple and easy to operate, can quickly reduce or eliminate the negative effects of difficult sludge sedimentation, deteriorated effluent quality and the like caused by sludge bulking, and improves the operation stability and the operation safety of the conventional sewage treatment plant.

Description

A Quorum Sensing-Based Bulk Control Method for Filamentous Sludge

technical field

The invention relates to the technical field of filamentous sludge bulking control, in particular to a quorum sensing-based filamentous sludge bulking control method.

Background technique

The activated sludge process has become the mainstream process in the field of sewage treatment. However, as a stubborn disease of activated sludge treatment process, sludge bulking phenomenon has always been an important problem affecting the stable operation of sewage treatment system. In the study of sludge bulking phenomenon, it is found that more than 90% of the sludge bulking problem is caused by the excessive growth of filamentous bacteria. Therefore, the control of filamentous sludge bulking plays an important role in the normal operation of sewage treatment plants.

At present, the commonly used filamentous sludge bulking control method is to add chemical agents such as oxidants to control the growth of filamentous bacteria, but this method not only kills filamentous bacteria but also damages other functional bacteria in the system, resulting in an imbalance of the ecosystem in the system. In addition, sludge bulking can also be controlled by adjusting the process operating conditions such as sludge load, sludge age, and sludge return ratio, but these methods have long periods and slow results, which are not conducive to practical applications.

Activated sludge, as an ecosystem with multiple bacterial groups, mainly relies on a large number of microorganisms to remove pollutants to achieve stable operation of the sewage treatment system, and the occurrence of filamentous sludge bulking is mainly due to the overgrowth of filamentous bacteria. The ecological balance of the group is broken. Quorum sensing is widely present in all kinds of microorganisms, and it is a phenomenon that controls its group behavior by generating sensory chemical signal molecules to achieve cell-to-cell communication. When the signal molecule reaches the threshold concentration, the homologous receptor binds to the signal molecule and triggers the signal transduction cascade, stimulates the expression of related genes in the bacteria, regulates the physiological behavior of the flora and the ecological relationship of the flora, and finally determines the population structure. Physiological functions and regulatory mechanisms that cannot be achieved by individual bacteria. However, in the prior art, there are few reports on the method for regulating the bulking of filamentous sludge based on quorum sensing.

Therefore, from the perspective of quorum sensing of filamentous bacteria in activated sludge systems, the development of an effective control method for filamentous sludge bulking based on quorum sensing regulation is of great significance to the occurrence of sludge bulking in sewage treatment plants.

SUMMARY OF THE INVENTION

In view of this, the present invention provides a quorum sensing-based filamentous sludge bulking control method. The method analyzes the samples with sludge bulking, analyzes the types and contents of filamentous bacteria and N-acylated homoserine lactones (AHLs) signal molecules that cause sludge bulking, and determines the AHLs signals that can inhibit sludge bulking. Molecules and then dosing the signal molecules exogenously to realize the control of filamentous sludge bulking.

In order to achieve the above object, the present invention adopts the following technical solutions:

A quorum sensing-based filamentous sludge bulking control method, comprising the following steps:

(1) Running the activated sludge reactor;

(2) Collect the activated sludge sample in the activated sludge reactor described in step (1), measure its sludge volume index (SVI), and conduct in-situ microscope observation to determine its sludge bulking degree and sludge volume Inflation type;

(3) taking the activated sludge sample described in step (2) and carrying out Gram staining and Neisser staining to identify the dominant filamentous bacteria that cause filamentous sludge bulking;

(4) taking the activated sludge sample described in step (2) to measure the type and content of its N-acylated homoserine lactones (AHLs) signal molecules;

(5) carrying out a correlation analysis between the AHLs signal molecules detected in step (4) and the filamentous sludge bulking, and determining the AHLs signal molecules that are negatively correlated with the filamentous sludge bulking;

(6) Add AHLs signal molecules negatively correlated with filamentous sludge bulking determined in step (5) into the activated sludge reactor, so as to realize the control of filamentous sludge bulking in the activated sludge reactor .

Mechanism: Filamentous bacteria sense the concentration of AHLs signal molecules outside the cell, that is, in the system. When the concentration of extracellular AHLs signal molecules is high, the corresponding receptor protein in the filamentous bacteria cell receives the signal and regulates the corresponding gene not to express, and then regulates Its physiological behavior inhibits the growth of filamentous bacteria and achieves the purpose of controlling the bulking of filamentous sludge.

Advantages: At present, the commonly used filamentous sludge bulking control method is to add chemical agents such as oxidants to control the growth of filamentous bacteria, but this method kills filamentous bacteria and also damages other functional bacteria in the system, leading to ecological problems in the system. The system is unbalanced; in addition, sludge bulking can also be controlled by adjusting the process operating conditions such as sludge load, sludge age, and sludge return ratio, but these methods have long periods and slow results, which are not conducive to practical applications. The method of the invention makes full use of the quorum sensing regulation mechanism between microorganisms, and according to the correlation between AHLs signal molecules and filamentous sludge bulking, targeted addition of AHLs signal molecules that inhibit the growth of filamentous bacteria, thereby realizing sludge bulking. control. The method is simple to operate, easy to implement, and can quickly realize the control of filamentous sludge bulking and the stable operation of the system.

Further, in the step (1), the dissolved oxygen concentration of the activated sludge reactor during aerobic aeration is controlled at 1.5-2.0 mg/L.

Further, the hydraulic retention time of the activated sludge reactor in step (1) is 8-20h.

Further, in the step (1), the activated sludge reactor inlet water adopts artificial preparation of simulated wastewater, using sodium acetate as the carbon source, ammonium sulfate as the nitrogen source, and dipotassium hydrogen phosphate as the phosphorus source, so that the artificial preparation simulates the wastewater. The COD concentration of the wastewater is 250-350mg/L, the ammonia nitrogen concentration is 50-70mg/L, and the phosphorus concentration is 5-7mg/L. At the same time, magnesium sulfate, calcium chloride, ferric chloride, boric acid, cobalt chloride and nickel chloride are added. , zinc sulfate, manganese chloride and copper sulfate provide major and trace elements, so that their concentrations are Mg ²⁺ : 2mg/L, Ca ²⁺ : 10mg/L, Fe ³⁺ : 0.3mg/L, B ³⁺ : 30μg/L, Co ²⁺ : 35μg/L, Ni ⁺ : ^35μg /L, Zn ²⁺ : 30μg/L, Mn ²⁺ : 30μg/L, Cu ²⁺ : 8μg/L, and sodium bicarbonate was added Adjust pH to 8.0.

Beneficial effects obtained: This setting not only meets the needs of normal growth of microorganisms, but also does not cause stress to microorganisms in the system due to excessive concentrations of COD, nitrogen and phosphorus. The above concentration settings refer to the concentration of domestic sewage in the sewage treatment plant.

Further, in the activated sludge reactor in step (1), the sludge concentration is controlled to be 3000-3500 mg/L, and the sludge age is 20-25 days.

The beneficial effects obtained: too high sludge concentration will reduce the sludge load, too low sludge concentration, high sludge load, too low or too high sludge load will be unfavorable for system operation; sludge age time If it is too short, some functional bacteria such as ammonia oxidizing bacteria and nitrite oxidizing bacteria will have a long generation time, which is not conducive to their growth.

Further, in step (1), the temperature of the activated sludge reactor is controlled to be 20-25°C.

Beneficial effects obtained: in this temperature range, all kinds of microorganisms can grow normally and maintain high activity. If the temperature is too low, it will easily lead to sludge expansion, which is not conducive to the growth of some functional bacteria. Part of the enzyme activity of microorganisms is inhibited, which is not conducive to the normal growth of microorganisms.

Further, the SVI determination in step (2) should be performed immediately after sampling, and the microscope in-situ observation should be performed within 0-2 hours.

Further, the AHLs signal molecules in step (4) are extracted by solid phase extraction, and determined by high performance liquid chromatography-mass spectrometry.

Further, in step (6), the concentration of AHLs signal molecules that are negatively correlated with the bulking of the filamentous sludge is 5ng/L-25ng/L.

The beneficial effects obtained: the above concentration is the effective concentration for regulating the expansion of the filamentous sludge.

Further, when the SVI value of the activated sludge reactor described in step (1) is stabilized below 150mL/g, the AHLs signal molecules that are negatively correlated with the bulking of filamentous sludge in step (6) will no longer be added. .

It can be seen from the above technical solutions that, compared with the prior art, the present invention has the following beneficial effects: simple and easy operation, and can quickly reduce or eliminate negative effects such as sludge settling difficulties and effluent quality deterioration caused by sludge bulking. Influence, improve the operation stability and operation safety of the existing sewage treatment plant. The invention controls sludge bulking from the perspective of quorum sensing regulation, effectively and reasonably utilizes the ecological effects of filamentous bacteria and other microbial communities, and can quickly realize the control of filamentous sludge bulking and the stable operation of the system.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only It is an embodiment of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to the provided drawings without creative work.

The accompanying drawing of Fig. 1 is a Gram-staining diagram of a sludge sample when filamentous sludge bulking occurs in Example 1 of the present invention;

The accompanying drawing of Fig. 2 is the change diagram of SVI and AHLs signal molecules during the operation of the SBR reactor in Example 1 of the present invention;

Fig. 3 accompanying drawing is the variation diagram of SVI after adding C6-HSL in the embodiment of the present invention 1;

Figure 4 is a diagram showing the Gram staining of sludge samples after filamentous sludge bulking control in Example 1 of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The medicaments required in the present invention are conventional experimental medicaments, which are purchased from commercial channels; the unmentioned experimental methods are conventional experimental methods, which will not be repeated here.

Example 1

The activated sludge reactor operated in this example is an SBR reactor with an effective volume of 4L. After the secondary sedimentation tank is inoculated to return the sludge, the sludge concentration is 3200mg/L and the SVI is 94mL/g. It operates in anoxic/aerobic mode, and runs 4 cycles per day, in which each cycle is 10 minutes of water inflow, 110 minutes of anaerobic/anoxic stirring, 180 minutes of aerobic aeration, 50 minutes of sedimentation, 7 minutes of drainage, and 3 minutes of idle time. The SBR reactor is controlled by a constant temperature water interlayer, the temperature of the reactor is 20±1℃, the dissolved oxygen concentration is controlled at 1.0～1.5mg/L during aerobic aeration, the water inlet and drainage are controlled by a peristaltic pump, and the drainage ratio is 50%. The residence time was 12h, and the sludge age was 25 days. During the operation, the influent of the SBR reactor was artificially prepared with simulated wastewater, with sodium acetate as the carbon source, ammonium sulfate as the nitrogen source, and dipotassium hydrogen phosphate as the phosphorus source, so that the COD concentration was 300 mg/L and the ammonia nitrogen concentration was 60 mg/L. L, the phosphorus concentration was 5 mg/L, and sodium bicarbonate was added to adjust the pH to 8.0. In addition, magnesium sulfate, calcium chloride, ferric chloride, boric acid, cobalt chloride, nickel chloride, zinc sulfate, manganese chloride, and copper sulfate were added to provide macro and trace elements, making their concentrations Mg ²⁺ : 2 mg, respectively /L, Ca ²⁺ : 10mg/L, Fe ³⁺ : 0.3mg/L, B ³⁺ : 30μg/L, Co ²⁺ : 35μg/L, Ni ⁺ : 35μg/L, Zn ²⁺ : 30μg/L , Mn ²⁺ : 30 μg/L, Cu ²⁺ : 8 μg/L.

Take the activated sludge sample in the SBR reactor for SVI measurement. The measurement method: take 100 mL of the activated sludge mixture and let it stand for 30 minutes, record its SV ₃₀ , then filter it with qualitative filter paper, put it in a 105 ℃ oven and dry it to constant weight. The sludge dry weight W was obtained, and the SVI was obtained as SV ₃₀ /W. After 12 days of operation, its SVI increased from 94mL/g to 152mL/g, and the existence of filamentous bacteria was observed in situ by microscope. At this time, the system had filamentous sludge bulking. Then, take the activated sludge sample for Gram staining. The staining method is as follows: take 5 mL of the activated sludge mixture and dilute it by 3 times, take 100 μL of the diluted mixture and spread it evenly on the glass slide, and use ammonium oxalate to crystallize it after air-drying. Initial staining with violet solution for 1 min, mordant staining with iodine solution for 1 min, destaining with 95% ethanol for 30 s, and counterstaining with safranin staining solution for 1 min. The Gram-stained samples were observed under a microscope. The filamentous bacteria were Gram-positive, and the hyphae were slender, smooth and curved, which conformed to the morphological characteristics of Microtharia. The fungus is Microtharia (Figure 1). At the same time, the AHLs signal molecules in the activated sludge samples were extracted by solid-phase extraction. The solid-phase extraction steps were as follows: 5 mL of chromatographic methanol and 5 mL of pure water were used to activate the Bond Elut ENV solid-phase extraction column, and then the 0.45 μm filter membrane was used to activate the Bond Elut ENV solid phase extraction column. 200 mL of the filtered water sample was loaded into the solid phase extraction column at a speed of 5-10 mL/min, and then rinsed with 5 mL of 5% methanol aqueous solution. After the solid phase extraction column was drained, 10 mL of chromatographic methanol was used to elute the extracted AHLs signal molecules. , and the eluate was collected, and the eluate was de-dissolved with a rotary evaporator, and the initial mobile phase was used to dilute to 2 mL. The type and content of AHLs signal molecules were determined by high performance liquid chromatography-mass spectrometry. The specific determination conditions are as follows. HPLC conditions: the flow rate was 0.2 mL/min, the injection volume was 10 μL, the mobile phase A was an aqueous solution containing 2 mM ammonium acetate and 0.1% formic acid, the mobile phase B was methanol, the total analysis time was 10 min, and the post-run was 1 min. Gradient elution conditions for good separation. Mass spectrometry conditions: use positive ion scanning mode, ion source is jet electrospray ion source (AJS-ESI), monitoring mode is multiple reaction monitoring (MRM) mode; drying gas temperature is 350 °C, flow rate is 8 L/min; nebulizer pressure 30psi, sheath gas temperature 350°C, sheath gas flow rate 11L/min, capillary voltage 3500V. After that, samples were taken every 2 days to measure SVI and AHLs signal molecules (see Figure 2), and were observed under a Gram staining microscope. Analysis showed that C6-HSL was significantly negatively correlated with SVI (p<0.01), and the Pearson correlation coefficient was -0.93.

After the SBR reactor runs for 40 days, C6-HSL is added to the system, and it is added to the SBR reactor together with the influent water. The concentration of C6-HSL after the addition is 15ng/L. After 2 days of dosing (that is, the 42nd day of system operation), the SVI decreased from 284mL/g to 273mL/g, and on the 64th day, the SVI decreased to 147mL/g, and then stabilized below 150mL/g (Figure 3). The Gram-staining diagram (Fig. 4) showed that the sludge floc had a compact structure, the microthiae mycelia were few and short and existed in the sludge floc, and empty cells were observed in the hyphae, indicating that the microthiae was about to die. On the 70th day, the dosing of the signal molecule C6-HSL was stopped, and the operation continued for 20 days, and the SVI was stable below 150mL/g.

The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the various embodiments can be referred to each other.

The above description of the disclosed embodiments enables any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended 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 (10)

1. a filamentous sludge bulking control method based on quorum sensing, is characterized in that, comprises the steps: (1) Running the activated sludge reactor; (2) collecting the activated sludge sample in the activated sludge reactor described in step (1), measuring its SVI, and carrying out in-situ microscope observation to determine its sludge bulking degree and sludge bulking type; (3) taking the activated sludge sample described in step (2) and carrying out Gram staining and Neisser staining to identify the dominant filamentous bacteria that cause filamentous sludge bulking; (4) taking the activated sludge sample described in step (2) to measure the type and content of its AHLs signal molecules; (5) carrying out a correlation analysis between the AHLs signal molecules detected in step (4) and the filamentous sludge bulking, and determining the AHLs signal molecules that are negatively correlated with the filamentous sludge bulking; (6) Add AHLs signal molecules negatively correlated with filamentous sludge bulking determined in step (5) into the activated sludge reactor, so as to realize the control of filamentous sludge bulking in the activated sludge reactor . 2. A quorum-sensing-based filamentous sludge bulking control method according to claim 1, characterized in that in step (1), the dissolved oxygen concentration of the activated sludge reactor during aerobic aeration is controlled at 1.5～2.0mg/L. 3 . The quorum sensing-based filamentous sludge bulking control method according to claim 1 , wherein the hydraulic retention time of the activated sludge reactor in step (1) is 8-20 h. 4 . 4. A quorum-sensing-based filamentous sludge bulking control method as claimed in claim 1, wherein the activated sludge reactor inlet water in step (1) adopts artificial preparation of simulated wastewater, and uses sodium acetate As the carbon source, ammonium sulfate is the nitrogen source, and dipotassium hydrogen phosphate is the phosphorus source, so that the COD concentration of the artificially prepared simulated wastewater is 250-350 mg/L, the ammonia nitrogen concentration is 50-70 mg/L, and the phosphorus concentration is 5-7 mg/L. L, at the same time adding magnesium sulfate, calcium chloride, ferric chloride, boric acid, cobalt chloride, nickel chloride, zinc sulfate, manganese chloride and copper sulfate to provide major and trace elements, so that their concentrations are Mg ²⁺ : 2mg /L, Ca ²⁺ : 10 mg/L, Fe ^{3 +} : 0.3 mg/L, B ³⁺ : 30 μg/L, Co ²⁺ : 35 μg/L, Ni ⁺ : 35 μg/L, Zn ²⁺ : 30 μg/L , Mn ²⁺ : 30 μg/L, Cu ²⁺ : 8 μg/L, in addition, sodium bicarbonate was added to adjust the pH to 8.0. 5 . The quorum sensing-based filamentous sludge bulking control method according to claim 1 , wherein the activated sludge reactor in step (1) is controlled to have a sludge concentration of 3000-3500 mg/ L, sludge age is 20 to 25 days. 6 . The quorum sensing-based filamentous sludge bulking control method according to claim 1 , wherein the temperature of the activated sludge reactor is controlled to be 20-25° C. in step (1). 7 . 7. A quorum sensing-based filamentous sludge bulking control method according to claim 1, wherein the SVI measurement in step (2) should be performed immediately after sampling, and the microscope in-situ observation should be at 0 within ~2h. 8 . A quorum sensing-based filamentous sludge bulking control method according to claim 1 , wherein the AHLs signal molecules described in step (4) are extracted by solid phase extraction, and high performance liquid chromatography is used for extraction. 9 . - Determination by mass spectrometry. 9 . A quorum sensing-based filamentous sludge bulking control method according to claim 1 , wherein the concentration of AHLs signal molecules negatively correlated with filamentous sludge bulking in step (6) is: 10 . 5ng/L～25ng/L. 10. A quorum sensing-based filamentous sludge bulking control method according to claim 1, characterized in that, when the SVI value of the activated sludge reactor in step (1) is stable below 150 mL/g , the AHLs signal molecules that are negatively correlated with the bulking of the filamentous sludge in step (6) are no longer added.

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