Preparation method and application of quorum sensing quenching agent-embedded chitosan slow-release gel particles
By preparing chitosan slow-release gel particles with encapsulated quorum quenchers, the problem of sludge bulking at low temperatures was solved, and the long-term synergistic effect of vanillin and chitosan was achieved, improving sludge settling performance and reducing costs.
Patent Information
- Application Number
- CN202511663766.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-13
- Publication Date
- 2026-01-23
AI Technical Summary
Under low-temperature conditions, the problem of sludge bulking in wastewater treatment plants is difficult to solve. Existing technologies for the direct addition of vanillin and chitosan have problems such as easy dilution and biodegradation, short action time, high cost, and difficulty in sustaining synergistic effects.
Chitosan sustained-release gel particles encapsulating quorum quenchers were prepared. Vanillin and chitosan were combined by ionic cross-linking to form stable spherical gel particles, which slowly released vanillin and chitosan to achieve long-term inhibition of EPS synthesis and flocculation.
It achieves a long-term synergistic effect between vanillin and chitosan, continuously improving sludge settling performance, reducing operating costs and complexity, and eliminating the risk of secondary pollution.
Smart Images
Figure CN121377262A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of sewage biological treatment, in particular to a preparation method of chitosan slow-release gel particles embedding quorum sensing quencher and application thereof. BACKGROUND
[0002] The sewage treatment plants in northern China generally face the problem of sludge bulking when operating at low temperature (<12℃) in winter. Low temperature stimulates the proliferation of filamentous bacteria and promotes the secretion of excess hydrophilic extracellular polymeric substances (EPS) by microorganisms, resulting in a sharp increase in sludge settling ratio (SV 30 ) and sludge volume index (SVI), difficulty in separating sludge and water in the secondary sedimentation tank, and deterioration of effluent quality.
[0003] Quorum sensing (QS) is an important mechanism of intercellular communication of microorganisms, and acyl-homoserine lactone (AHL) signal molecules regulate the synthesis and secretion of EPS. Vanillin, as a natural and safe quorum sensing quencher (QQ), can effectively interfere with the AHL-mediated signal pathway and inhibit the excessive production of EPS at the molecular level, providing a new idea for controlling sludge bulking. Chitosan is a natural cationic polysaccharide that can efficiently flocculate sludge through electro-neutralization and adsorption bridging, rapidly improving the settling property.
[0004] However, if vanillin and chitosan are directly added to the sewage treatment system, the following defects exist: (1) vanillin is easily diluted and biodegraded, has a short action time, needs to be added frequently, and has high cost; (2) the flocculation effect of directly added chitosan is instantaneous and short, and cannot cope with the continuously produced EPS; (3) the synergistic effect of the two cannot be sustained. Therefore, developing a preparation that can make the two synergistically and long-acting in the sludge system has become a technical problem to be solved in the field. SUMMARY
[0005] The present application is to solve the technical problem of low-temperature sludge bulking in sewage treatment plants, and to provide a preparation method of chitosan slow-release gel particles embedding quorum sensing quencher and application thereof.
[0006] The preparation method of chitosan slow-release gel particles embedding quorum sensing quencher of the present application is carried out according to the following steps:
[0007] I. Preparation of chitosan solution: dissolve chitosan powder in acetic acid aqueous solution, then stir until completely dissolved to prepare chitosan solution;
[0008] II. Loading of vanillin: add vanillin powder to the chitosan solution prepared in step I, continuously stir to make it uniformly dispersed, and obtain a chitosan-vanillin mixture;
[0009] III. Ionic cross-linking gelation: the chitosan-vanillin mixture obtained in step II is added dropwise into the sodium tripolyphosphate solution using a syringe or dropper; slow stirring is continuously performed during the dropwise addition, and during this process, the chitosan cations and the sodium tripolyphosphate anions undergo an ionic cross-linking reaction, and instantaneously form stable spherical gel particles;
[0010] IV. Post-treatment: after the chitosan-vanillin mixture is completely added, solidification is continued by stirring; then the gel particles are collected, repeatedly washed with deionized water to remove residual reagents, and finally freeze-dried or dried at low temperature to obtain the composite sustained-release gel particles.
[0011] The application further provides the use of the composite sustained-release gel particles prepared above to alleviate the swelling of activated sludge under low-temperature conditions.
[0012] The composite sustained-release gel particles prepared by the application use chitosan gel as a carrier, and the quorum quenching agent vanillin is embedded therein, which can continuously and slowly release the quorum quenching agent (vanillin) and the flocculating component (chitosan) in the sewage treatment system, thereby achieving the synergistic effect of long-term source inhibition of sludge EPS secretion and instant and continuous flocculation of sludge flocs, and fundamentally and long-term improving the sludge swelling problem under low-temperature and low-carbon-nitrogen-ratio conditions.
[0013] The application has the following beneficial effects:
[0014] 1. The application first combines the quorum quenching agent (vanillin) and the natural flocculant (chitosan) through a sustained-release carrier; the vanillin is released for a long time and slowly, continuously quenches the QS signal, and then inhibits the synthesis of EPS (especially polysaccharides); the chitosan is synchronously released, instantaneously flocculates the existing EPS and dispersed bacterial bodies, and the two are perfectly synergistic in time and function, and fundamentally and long-term improve the sludge settling performance;
[0015] 2. The chitosan gel network prepared by the ionic cross-linking method can firmly embed the vanillin and part of the chitosan molecules therein, slowly swell and release the active ingredients in water, effectively avoiding rapid loss and degradation; once added, the stable effect can be maintained for several weeks to several months, greatly reducing the operation cost and operation complexity;
[0016] 3. The chitosan and vanillin in the application are both biodegradable natural products, without secondary pollution risk, and have good environmental compatibility;
[0017] 4. The composite sustained-release gel particles prepared by the application have good mechanical strength, can be directly added to the existing treatment process without the need for modification of facilities; under low-temperature and low-carbon-nitrogen-ratio conditions, the SVI and SV 30 of the sludge can be significantly reduced, the sludge swelling is inhibited, and the stable operation of the system is ensured. BRIEF DESCRIPTION OF DRAWINGS
[0018] Figure 1 Figure 4 is a graph showing the change of sludge volume index (SVI) of different treatment groups in Test 2 over time;
[0019] Figure 2 Figure 5 is a graph showing the change of protein and polysaccharide content in sludge EPS of different treatment groups in Test 2. DETAILED DESCRIPTION
[0020] Embodiment 1: The present embodiment is a method for preparing a chitosan sustained-release gel particle embedded with a quorum quenching agent, which is performed according to the following steps:
[0021] Step 1: Preparation of a chitosan solution: Dissolve chitosan powder in an aqueous acetic acid solution, and then stir until completely dissolved to prepare a chitosan solution;
[0022] Step 2: Loading of vanillin: Add vanillin powder to the chitosan solution prepared in Step 1, and continuously stir to uniformly disperse, to obtain a chitosan-vanillin mixture;
[0023] Step 3: Ionic cross-linking gelation: Use a syringe or dropper to add the chitosan-vanillin mixture obtained in Step 2 dropwise to a sodium tripolyphosphate solution; continuously stir slowly during the process, and an ionic cross-linking reaction between the chitosan cations and the sodium tripolyphosphate anions occurs instantaneously to form stable spherical gel particles;
[0024] Step 4: Post-treatment: After the chitosan-vanillin mixture is completely added, continue to stir and solidify; then collect the gel particles, repeatedly wash with deionized water to remove residual reagents, and finally freeze-dry or low-temperature dry to obtain the composite sustained-release gel particles.
[0025] Embodiment 2: The present embodiment differs from Embodiment 1 in that the mass fraction of the aqueous acetic acid solution in Step 1 is 0.5% to 2%. Other aspects are the same as Embodiment 1.
[0026] Embodiment 3: The present embodiment differs from Embodiment 2 in that the mass fraction of chitosan in the chitosan solution in Step 1 is 1.5% to 4%. Other aspects are the same as Embodiment 2.
[0027] Embodiment 4: The present embodiment differs from Embodiment 3 in that the mass of vanillin in the chitosan-vanillin mixture in Step 2 is 0.5% to 5% of the mass of chitosan. Other aspects are the same as Embodiment 3.
[0028] Embodiment five: different from embodiment four, the mass fraction of the sodium tripolyphosphate solution in step three is 1% to 5%. The rest is the same as embodiment four.
[0029] Embodiment six: different from embodiment five, the volume ratio of the chitosan-vanillin mixed solution to the sodium tripolyphosphate solution in step three is 1:(5-10). The rest is the same as embodiment five.
[0030] Embodiment seven: different from embodiment six, the rotating speed of the slow stirring in step three is 150 rpm to 300 rpm. The rest is the same as embodiment six.
[0031] Embodiment eight: different from embodiment seven, after the chitosan-vanillin mixed solution is completely added in step four, continue to stir for 30 min to 60 min; then, the gel particles are collected by a screen, repeatedly washed with deionized water to remove residual reagents, and finally freeze-dried or dried at a low temperature below 40℃ to obtain the composite slow-release gel particles. The rest is the same as embodiment seven.
[0032] Embodiment nine: the application of the composite slow-release gel particles prepared in embodiment eight, specifically applied to alleviate the swelling of activated sludge under low temperature conditions.
[0033] Embodiment ten: different from embodiment nine, the application method of the composite slow-release gel particles is: the composite slow-release gel particles are added to the biochemical reaction zone of the sewage treatment system, and the adding concentration is 50 mg / L to 300 mg / L. The rest is the same as embodiment nine.
[0034] The following tests are used to verify the present application:
[0035] Test one: a preparation method of chitosan slow-release gel particles embedding quorum quenching agent, specifically performed according to the following steps:
[0036] I. Preparation of chitosan solution: dissolve chitosan powder in acetic acid aqueous solution, then stir for 4 h until completely dissolved to prepare chitosan solution;
[0037] The mass fraction of the acetic acid aqueous solution in step one is 1%;
[0038] The mass fraction of chitosan in the chitosan solution in step one is 2%;
[0039] II. Vanillin loading: Vanillin powder was added to the chitosan solution prepared in step I, and stirred for 2 h to obtain a chitosan-vanillin mixture; the mass of vanillin in the chitosan-vanillin mixture was 2% of the mass of chitosan;
[0040] III. Ionic cross-linking gelation: The chitosan-vanillin mixture prepared in step II was added dropwise into the sodium tripolyphosphate solution using a 5 mL syringe; slow stirring was continuously performed at a speed of 200 rpm during the dropwise addition; the chitosan cation and the sodium tripolyphosphate anion were cross-linked to form stable spherical gel particles instantaneously; the mass fraction of the sodium tripolyphosphate solution was 2%; the volume ratio of the chitosan-vanillin mixture to the sodium tripolyphosphate solution was 1:8;
[0041] IV. Post-treatment: After the chitosan-vanillin mixture was completely added, stirring was continued for 45 min; then the gel particles were collected by a screen, washed with deionized water for 3 times to remove residual reagents, and finally freeze-dried for 24 h to obtain dry composite sustained-release gel particles with a diameter of 2 mm to 3 mm.
[0042] Test II: Verification of the application effect of the composite sustained-release gel particles
[0043] Test setup: Three parallel SBR reactors were set up in the laboratory, with an effective volume of 4 L and a drainage ratio of 40%; the reactors were operated for 3 cycles per day, with each cycle lasting for 8 h. The operation conditions of the reactors were simulated to be similar to the operation conditions of an Orbal oxidation ditch in a northern wastewater treatment plant, i.e., low temperature (10±1℃) and low carbon-nitrogen ratio (influent COD≈110 mg / L, TN≈28 mg / L). All the reactors were inoculated with expanded sludge, and the initial SVI of the sludge was 90% and the SVI was 200 mL / g. 30
[0044] SBR operation process control:
[0045] 1) 10 min of water feeding;
[0046] 2) 3 h of mixed micro-aeration reaction (stirring and micro-aeration were performed simultaneously); 1 h+48 min of anoxic reaction (only stirring was performed without aeration); 1 h+12 min of high-aeration reaction (high-aeration operation);
[0047] 3) 60 min of static sedimentation (no aeration and stirring were performed during the sludge static sedimentation);
[0048] 4) 10 min of water drainage, and 40% of wastewater was supplemented in each cycle;
[0049] 5) 40 min of static state without stirring (no stirring or aeration was performed).
[0050] The analysis test uses artificially prepared simulated domestic sewage, glucose as carbon source, NH4Cl and NaNO3 as nitrogen source, wherein NaNO3 provides NO3 - -N, KH2PO4 as phosphorus source. NaHCO3 is added to supplement the alkalinity of the water to meet the requirement of the nitrification reaction on the alkalinity. MgSO4 and CaCl2 are added to meet the requirement of the microorganism of the activated sludge on Mg 2＋ and Ca 2＋ ions, and the nutrient solution is added to supplement trace elements to meet the requirement of the microorganism on nutrition (1 mL·L -1 ). The water composition is shown in Tables 1 and 2.
[0051] Table 1: Water parameter table
[0052]
[0053] Table 2: Water composition table
[0054]
[0055] The initial sludge has poor settling performance, 230 mg / L of sodium acetate is added in the anoxic section as a denitrification carbon source to improve the nitrogen removal efficiency of the system, and the TN removal rate reaches 93.6%. The reactor temperature is controlled at 10±1℃, and the SVI value is stable at about 200 mL / g, and the sludge continuously occurs malignant swelling.
[0056] The comparative test is divided into three groups, namely, a blank control group R1, without adding any medicament; a comparison group R2, directly adding vanillin and chitosan, 0.5 mg / L of vanillin and 5 mg / L of chitosan powder are directly added every day; and an experimental group R3, adding the prepared composite slow-release gel particles in the test once on the first day, and the adding amount is 100 mg / L.
[0057] Figure 1 The SVI value of the sludge of the different treatment groups of the test two changes with time is shown in the comparative graph, it can be seen that the SVI value of R1 (blank control) is always at a high level of 200~250 mL / g, and the sludge is seriously swollen. R2 (direct addition): within 3 days of the initial addition, the SVI value rapidly decreases to about 150 mL / g, and the EPS content slightly decreases; but after one week, with the degradation and loss of the medicament, the SVI value and the EPS content rapidly rise to the similar level of R1, indicating that the direct addition effect is short-lived. R3 (the application): after the addition, the SVI value steadily decreases to below 170 mL / g within 7 days, and is always stable in a good range of 140 mL / g~160 mL / g within the test period of 40 days.
[0058] Figure 2Figure 2 is a graph showing the changes in the contents of protein and polysaccharide in sludge EPS of different treatment groups in Test 2. It can be seen that, compared with the blank control (R1) and the direct addition group (R2), after the addition of the composite slow-release gel particles prepared in Test 1 (R3), the total polysaccharide (PS) content in the EPS is significantly reduced (from 105.42 mg / L of R1 to 61.06 mg / L of R3), especially the loosely attached polysaccharide (LB-PS) is greatly reduced, which confirms that the quorum quenching effect of vanillin effectively inhibits the excessive secretion of hydrophilic EPS. The increase of the protein / polysaccharide (PN / PS) ratio proves that the quorum quenching effect of vanillin is continuously and effectively exerted.
Claims
1. A method for preparing a chitosan sustained-release gel particle embedding a quorum sensing quencher, characterized by The preparation method is carried out according to the following steps: I. Preparation of chitosan solution: chitosan powder is dissolved in acetic acid aqueous solution, and then stirred until completely dissolved to prepare chitosan solution; II. Loading of vanillin: vanillin powder is added to the chitosan solution prepared in step I, and uniform dispersion is achieved by continuous stirring to obtain a chitosan-vanillin mixture; III. Ionic cross-linking gelation: the chitosan-vanillin mixture obtained in step II is added dropwise into a sodium tripolyphosphate solution using a syringe or dropper; slow stirring is continuously performed during the dropwise addition, and during this process, ionic cross-linking reaction occurs between chitosan cations and sodium tripolyphosphate anions, and stable spherical gel particles are formed instantaneously; IV. Post-treatment: after the chitosan-vanillin mixture is completely added, continue to stir and solidify; then collect the gel particles, wash repeatedly with deionized water to remove residual reagents, and finally freeze-dry or low-temperature dry to obtain composite sustained-release gel particles.
2. A process for the preparation of a chitosan sustained release gel particle embedded with a quorum sensing quencher according to claim 1, characterized in that The mass fraction of the acetic acid aqueous solution in step I is 0.5% to 2%.
3. A process for the preparation of a chitosan sustained release gel particle embedded with a quorum sensing quencher according to claim 2, characterized in that The mass fraction of chitosan in the chitosan solution in step I is 1.5% to 4%.
4. The method of claim 1, wherein the method is characterized by The mass of vanillin in the chitosan-vanillin mixture in step II is 0.5% to 5% of the mass of chitosan.
5. The method of claim 1, wherein the method is characterized by The mass fraction of the sodium tripolyphosphate solution in step III is 1% to 5%.
6. A process for the preparation of a chitosan sustained release gel particle embedding a quorum sensing quencher according to claim 5, characterized in that The volume ratio of the chitosan-vanillin mixture to the sodium tripolyphosphate solution in step III is 1:(5-10).
7. The method for preparing chitosan sustained-release gel particles encapsulating a quorum quencher according to claim 1, characterized in that... The stirring speed in step III is 150 rpm to 300 rpm.
8. The method for preparing chitosan sustained-release gel particles encapsulating a quorum quencher according to claim 1, characterized in that... After the chitosan-vanillin mixture is completely added in step IV, continue to stir and solidify for 30 min to 60 min; then collect the gel particles using a screen, wash repeatedly with deionized water to remove residual reagents, and finally freeze-dry or low-temperature dry below 40°C to obtain composite sustained-release gel particles.
9. Use of a chitosan sustained-release gel particle embedding a quorum sensing quencher according to claim 1, characterized in that The chitosan sustained-release gel particles are applied to alleviate the swelling of activated sludge under low temperature conditions.
10. Use of a chitosan sustained-release gel particle embedding a quorum sensing quencher according to claim 9, characterized in that The application method of the composite sustained-release gel particles is: the composite sustained-release gel particles are added to the biochemical reaction zone of the sewage treatment system at a concentration of 50 mg / L to 300 mg / L.