Method for promoting biofilm formation on MBBR fillers

Abstract

The application discloses a method for promoting biofilm formation of MBBR fillers and belongs to the technical field of sewage treatment. The method for promoting biofilm formation of MBBR fillers utilizes microbial signal transmission and a microbial quorum sensing (QS) mechanism, realizes rapid and large-scale colonization of microorganisms and increase of the thickness of a biofilm, and effectively reduces the ammonia nitrogen content in sewage. The reactor using pure film operation is used for treating rural domestic sewage, and the removal rates of COD, ammonia nitrogen and total nitrogen are above 98.6%, 93.2% and 78.1% respectively.

Description

Technical Field

[0001] This invention relates to a wastewater treatment method for promoting biofilm formation on MBBR packing material, belonging to the field of wastewater treatment technology. Background Technology

[0002] With economic development and improved living standards, there has been a significant increase in domestic wastewater, industrial wastewater, and agricultural non-point source pollution. The nitrogenous substances in this polluted wastewater are continuously discharged into water bodies, causing severe eutrophication problems in rivers, lakes, and other bodies of water. This situation has not only led to significant degradation of ecosystems but also greatly diminished their ecosystem service functions.

[0003] Therefore, developing efficient and low-cost wastewater treatment technologies, especially for the deep removal of ammonia nitrogen and total nitrogen, has become an urgent need in the environmental protection field. Existing wastewater treatment methods, such as oxidation ditches and SBRs, can remove pollutants from wastewater to some extent, but they have limitations in terms of treatment efficiency, operating costs, and operational complexity. Particularly when treating wastewater with high concentrations of ammonia nitrogen and total nitrogen, they often require long treatment cycles and high energy consumption, and the treatment effect is unstable, making it difficult to meet increasingly stringent environmental emission standards.

[0004] In the prior art, Chinese patent application CN116813081A discloses an SBR reactor, inoculated with activated sludge that has been placed in anoxic conditions for one month, with MLSS = 2700-3300 mg / L; influent time 5 min, reaction time 35-90 min, settling time 30 min, effluent time 5 min; stirring throughout the reaction cycle; hydraulic retention time (HRT) continuously shortened according to changes in effluent nitrite concentration during the reaction; effluent ratio 50%, HRT = 70-180 min; C6-HSL is added exogenously to simulate wastewater, with a concentration of 20-35 mg / g-VSS after addition to the reactor; 1-2 cycles are run daily; simulated wastewater is used instead of actual wastewater for the first half month to stabilize water quality, after which actual nitrite-containing wastewater is treated. This prior art mainly treats common urban domestic sewage and does not address the treatment of rural domestic sewage. Rural domestic sewage differs significantly from urban domestic sewage in terms of volume, composition, concentration, and treatment conditions, exhibiting characteristics such as higher pollutant concentrations and greater fluctuations in water quality.

[0005] Chinese patent application CN109019860A discloses a device and method for treating municipal wastewater using a simultaneous nitrification-denitrification membrane-biofilm reactor. The method involves adding sponge packing material at a volume ratio of 30%-50%, setting the aeration rate to 0.8-1.2 L / min during the start-up phase, and setting the hydraulic retention time to 24 h for 1-10 days, 18 h for 11-20 days, and 12 h after 21 days, allowing suspended sludge to adhere to the carrier and form a biofilm. During the stabilization phase, the aeration rate is changed from 0.8-1.2 L / min to 0.3-0.6 L / min. This prior art primarily treats common municipal wastewater and does not address rural domestic sewage. Rural domestic sewage differs significantly from urban domestic sewage in terms of volume, composition, concentration, and treatment conditions, exhibiting characteristics such as higher pollutant concentrations and greater water quality fluctuations.

[0006] Chinese patent publication CN110540292B discloses an enhanced simultaneous nitrification and denitrification process by adding AHL signaling molecules to a biological moving bed process. This process improves the biological moving bed process, including moving bed biofilm processes and biofilm-activated sludge composite processes, by adding AHL signaling molecules (a mixture of C4, C8, C14, etc.) to promote quorum sensing QS, which is crucial for bacterial biofilm formation. However, this technology suffers from poor total nitrogen removal efficiency.

[0007] In moving bed biofilm reactors (MBBRs), biofilm formation on the packing material is one of the key technologies determining reactor performance. The biofilm formation process typically involves microbial attachment, colonization, reproduction, and metabolism. Microbial attachment to the packing surface is a bottleneck during reactor startup; traditional biofilm formation processes suffer from slow colonization rates and low biofilm formation efficiency. Because microorganisms need time to adapt to the environment and form a stable biofilm, traditional methods often require a long start-up period to achieve good wastewater treatment results. This not only prolongs start-up time but also reduces the overall treatment efficiency of the reactor, especially during high loads or sudden pollution events, easily leading to reactor instability and even system failure. In existing technologies, most MBBR packing material biofilm formation methods rely on natural biofilm formation, but this method results in a slow formation rate, and the thickness and quality of the biofilm are difficult to guarantee.

[0008] In summary, how to effectively reduce ammonia nitrogen content is also an urgent problem to be solved in the field of wastewater treatment. Summary of the Invention

[0009] To address the shortcomings of existing technologies, this invention proposes a wastewater treatment method that promotes biofilm formation in MBBR packing. This method utilizes microbial signal transduction and quorum sensing (QS) mechanisms to achieve rapid and large-scale colonization of microorganisms and increase biofilm thickness, while effectively reducing ammonia nitrogen content in wastewater.

[0010] Signal transduction among microorganisms, especially quorum sensing mechanisms, plays a crucial role in microbial colonization, regulation of gregarious behavior, and biofilm formation. Quorum sensing signaling molecules are low-molecular-weight compounds secreted by some microorganisms. These signaling molecules can transmit information between microbial communities. When the concentration of signaling molecules in the community reaches a certain threshold, the microorganisms collectively respond and exhibit coordinated behaviors, including population proliferation, metabolite transformation, enhanced drug resistance, and biofilm formation.

[0011] In wastewater treatment, regulating the concentration of quorum sensing signaling molecules can effectively promote rapid microbial attachment and biofilm formation. Compared to traditional methods, signaling molecules are more efficient in regulating microbial community behavior, significantly shortening biofilm attachment time and increasing the colonization rate of microorganisms on the packing surface. Utilizing signaling molecules, especially quorum sensing signaling molecules, can enable microorganisms to complete biofilm colonization and thick film formation in a shorter time, significantly shortening the start-up cycle of biofilm reactors and effectively improving reactor treatment efficiency.

[0012] The first objective of this invention is to provide a method for promoting biofilm formation on packing materials, the method comprising:

[0013] The reactor was inoculated with activated sludge from an aerobic tank and MBBR suspended packing was added. Wastewater was added to the reactor, and the signaling molecule C6-HSL was added during the reaction. The biofilm packing was obtained after the reactor had been running for four weeks.

[0014] The operating reactor includes influent, aeration and stirring, sedimentation, effluent, and stagnation.

[0015] During the first week, maintain the activated sludge concentration at 2800-3500 mg / L and add 1-10 nmol / L of the signaling molecule C6-HSL.

[0016] In the second week, maintain the activated sludge concentration at 1500-2500 mg / L and add 20-40 nmol / L of the signaling molecule C6-HSL.

[0017] In the third week, maintain the activated sludge concentration at 500-1500 mg / L and add 40-60 nmol / L of the signaling molecule C6-HSL.

[0018] In the fourth week, maintain the activated sludge concentration at 0 mg / L and add 90-110 nmol / L of the signaling molecule C6-HSL.

[0019] In one embodiment, the reactor is an SBR reactor.

[0020] In one embodiment, the working volume of the SBR reactor is 4L and the drainage ratio is 1 / 4.

[0021] In one embodiment, the MBBR suspension packing is K3 packing.

[0022] In one embodiment, MBBR suspended packing is added to the SBR reactor at a dosage of 20%-50% (v / v) of the reactor's effective volume; activated sludge is inoculated into the SBR reactor at a dosage of MLSS = 2800-3500 mg / L of the reactor's effective volume; the total hydraulic retention time (HRT) of the SBR reactor is 5-10 h, including influent, aeration and stirring, sedimentation, effluent, and stagnation stages; 10-100 nmol / L of the signaling molecule C6-HSL is added to the influent; the biofilm formation time in the SBR reactor is divided into four stages, with the dosage of C6-HSL gradually increasing over time; the sludge concentration is gradually reduced by sludge discharge, ultimately resulting in a wastewater treatment system operating with a pure biofilm.

[0023] In one embodiment, the wastewater is rural domestic sewage, and its components include 100-300 mg / L COD and 20-100 mg / L NH4. + -N, 1-20 mg / L PO4 3- -P, 1-20TP mg / L, 20-150mg / L TN, 0-20mg / L NO3 - -N, 0-10 mg / L NO2 - -N.

[0024] In one embodiment, when operating the reactor, the influent time is 5-10 min; the aeration and stirring time is 280-350 min; the sedimentation time is 25-60 min; the effluent time is 5-10 min; and the stagnation period is 15-30 min.

[0025] In one implementation, the pH is maintained at 6.5–7.5 while the reactor is running.

[0026] In one embodiment, the inoculum amount (MLSS) of activated sludge in the aerobic tank is 2800-3500 mg / L;

[0027] Optionally, the inoculum amount of activated sludge in the aerobic tank is 3000 mg / L (MLSS).

[0028] In one embodiment, the amount of MBBR suspension packing added is 20%-50% v / v;

[0029] Optionally, the amount of MBBR suspension packing added is 30% v / v.

[0030] The second objective of this invention is to provide a method for simultaneously improving the removal rates of COD, ammonia nitrogen, and total nitrogen in wastewater, using a pure membrane reactor for wastewater treatment; the method for preparing the pure membrane reactor is as follows:

[0031] The reactor was inoculated with activated sludge from an aerobic tank and MBBR suspended packing was added. Wastewater was added to the reactor, and the signaling molecule C6-HSL was added during the reaction. After running the reactor for four weeks, a reactor operating purely on membranes was obtained.

[0032] The operating reactor includes influent, aeration and stirring, sedimentation, effluent, and stagnation.

[0033] During the first week, maintain the activated sludge concentration at 2800-3500 mg / L and add 0-10 nmol / L of the signaling molecule C6-HSL.

[0034] In the second week, maintain the activated sludge concentration at 1500-2500 mg / L and add 20-40 nmol / L of the signaling molecule C6-HSL.

[0035] In the third week, maintain the activated sludge concentration at 500-1500 mg / L and add 40-60 nmol / L of the signaling molecule C6-HSL.

[0036] In the fourth week, maintain the activated sludge concentration at 0 mg / L and add 90-110 nmol / L of the signaling molecule C6-HSL.

[0037] In one embodiment, the wastewater is rural domestic sewage, and its components include 100-300 mg / L COD and 20-100 mg / L NH4. + -N, 1-20 mg / L PO4 3- -P, 1-20TP mg / L, 20-150mg / L TN, 0-20mg / L NO3 - -N, 0-10 mg / L NO2 - -N.

[0038] In one embodiment, when operating the reactor, the influent time is 5-10 min; the aeration and stirring time is 280-350 min; the sedimentation time is 25-60 min; the effluent time is 5-10 min; and the stagnation period is 15-30 min.

[0039] In one embodiment, the inoculum amount (MLSS) of activated sludge in the aerobic tank is 2800-3500 mg / L;

[0040] Optionally, the inoculum amount of activated sludge in the aerobic tank is 3000 mg / L (MLSS).

[0041] The addition amount of MBBR suspension packing is 20%-50% v / v;

[0042] Optionally, the amount of MBBR suspension packing added is 30% v / v.

[0043] A third objective of this invention is to provide the application of any of the above-described methods in wastewater treatment.

[0044] Beneficial effects of the present invention

[0045] Rural domestic sewage refers to wastewater generated in the daily lives of rural residents, mainly from household activities, sanitation facilities, kitchens, washing, and animal husbandry. Compared with urban domestic sewage, rural domestic sewage has several distinct characteristics that require special consideration in pollution control and water treatment. The main characteristics of rural domestic sewage include: small and fluctuating volume, diverse pollutant composition, high pollutant concentration, dispersion and uneven distribution, and complex pollution sources. This presents numerous challenges to rural sewage treatment, necessitating site-specific solutions such as establishing small-scale decentralized sewage treatment facilities, promoting ecological treatment technologies, and strengthening rural sewage management to ensure effective sewage treatment and reduce environmental pollution.

[0046] This invention provides a method for promoting biofilm formation in MBBR packing material. This method utilizes microbial signal transduction and quorum sensing (QS) mechanisms to achieve rapid and large-scale colonization of microorganisms and increase biofilm thickness, while effectively reducing ammonia nitrogen content in wastewater. Specifically:

[0047] This invention uses a pure membrane reactor to treat rural domestic sewage, achieving a COD removal rate of over 98.6%, an ammonia nitrogen removal rate of over 93.2%, and a total nitrogen removal rate of over 78.1%. Attached Figure Description

[0048] Figure 1The images show a comparison of biofilm formation effects. The left image represents Example 1, where the biofilm is uniform and stable: a stable biofilm is evenly attached to the packing surface, with a moderate thickness, which is beneficial for microbial growth and reproduction. The biofilm exhibits strong adhesion: the packing surface displays strong hydrophilicity or hydrophobicity, effectively adsorbing microorganisms and ensuring the biofilm adheres firmly and is not easily detached. The biofilm also exhibits high activity: the microbial community after biofilm formation has high activity, forming a stable ecosystem on the packing surface and promoting the degradation and transformation of organic matter. The right image represents Comparative Example 3, where the biofilm is uneven: the biofilm on the packing surface is thin and unevenly distributed, resulting in insufficient biodegradation capacity. It also exhibits poor adhesion: the hydrophilicity or hydrophobicity of the packing surface is unsuitable, making it difficult for microorganisms to attach. Furthermore, the biofilm is unstable: the biofilm is easily affected by changes in the external environment, such as fluctuations in temperature and pH, leading to instability or damage to the membrane. Finally, the biofilm exhibits low activity: after biofilm formation, the microbial community has low activity and cannot effectively degrade or treat organic matter. Detailed Implementation

[0049] 1. Raw materials involved in the following examples and comparative examples:

[0050] K3 packing was purchased from Sprun Technology Co., Ltd.

[0051] The signaling molecule C6-HSL was purchased from Aladdin;

[0052] The sludge from the aerobic tank originated from the Yixing Concept Factory.

[0053] 2. Composition of activated sludge in aerobic tank:

[0054] aerobic bacteria

[0055] Aerobic bacteria degrade organic and inorganic matter through oxidation in aerobic environments. They typically use organic matter as a carbon source and oxygen as an electron acceptor to carry out aerobic respiration, playing a core role in removing pollutants.

[0056] Main types:

[0057] Heterotrophic bacteria: These bacteria use organic matter as a carbon source and respire with oxygen to degrade organic pollutants in water. They are the main force in degrading organic matter in aerobic ponds, capable of breaking down carbon sources in water (such as COD and BOD) into carbon dioxide and water, thus reducing organic pollutants in the water.

[0058] Autotrophic bacteria: These bacteria use inorganic substances (such as ammonia nitrogen and nitrates) as a carbon source to carry out redox reactions. The most common type is nitrifying bacteria, which participate in the nitrogen cycle.

[0059] Nitrifying bacteria: such as Nitrosomonas and Nitrifying bacteria. Nitrifying bacteria convert ammonia nitrogen (NH3) into nitrite (NO2). - It is then further converted into nitrate (NO3). - It participates in nitrogen removal, and nitrification is an important pathway for the removal of ammonia nitrogen from wastewater.

[0060] Denitrifying bacteria, such as Pseudomonas and Bacillus, are bacteria that can denitrify nitrates (NO3) in anaerobic environments. - These bacteria reduce nitrates to nitrogen gas (N2), and are typically active in the transition zone between aerobic and anoxic tanks or under certain specific conditions. They reduce nitrates to nitrogen gas, participating in nitrogen removal (denitrification), and play a particularly important role in nitrogen recirculation processes in wastewater treatment.

[0061] 4. The detection methods used in the following examples and comparative examples:

[0062] (1) Methods for determining COD:

[0063] The potassium dichromate method is currently the most widely used and standard method for COD determination. This method uses a strong oxidant (potassium dichromate) to oxidize organic matter in water under acidic conditions, producing carbon dioxide and water. The COD value is calculated by measuring the amount of potassium dichromate consumed during the reaction.

[0064] (2) Methods for determining and calculating ammonia nitrogen removal rate:

[0065] Nessler's reagent colorimetric method: Nessler's reagent (containing mercuric chloride and sodium chloride) reacts with ammonia nitrogen to form a yellow complex; the higher the concentration of ammonia nitrogen, the deeper the color. The concentration of ammonia nitrogen can be calculated by measuring the absorbance of the sample.

[0066] Ammonia nitrogen removal rate (%) = (Influent ammonia nitrogen concentration - Effluent ammonia nitrogen concentration) / Influent ammonia nitrogen concentration × 100%

[0067] (3) Methods for determining and calculating total nitrogen removal rate:

[0068] Persulfate digestion method: Persulfate reacts with nitrogen in the water sample at high temperature to form nitrate, and then the absorbance is measured by reacting with a specific reagent (such as diazacyclopropene reagent).

[0069] Total nitrogen removal rate (%) = (Influent total nitrogen concentration - Effluent total nitrogen concentration) / Influent total nitrogen concentration × 100%

[0070] (4) Methods for measuring biofilm thickness:

[0071] Scanning electron microscopy (SEM)

[0072] Sample collection: Remove the biofilm from the packing material and cut it into samples suitable for SEM observation.

[0073] Drying treatment: The biofilm sample is dried by freezing or air drying to avoid deformation of the membrane structure.

[0074] Gold plating: To improve image clarity, the sample needs to be plated with a thin metal film (such as gold or platinum) in a vacuum.

[0075] SEM observation: The surface morphology of the biofilm was observed under a scanning electron microscope, and its thickness was measured.

[0076] Example 1: A method for promoting biofilm formation in filler by adding signaling molecule C6

[0077] A method for promoting biofilm formation in packing materials by using exogenously added signaling molecules, the method is as follows:

[0078] An SBR reactor with a working volume of 4L and a effluent ratio of 1 / 4 was used. Activated sludge was inoculated into the aerobic tank at an inoculation rate of MLSS = 3000 mg / L (i.e., 12000 mg). MBBR suspended packing (K3 packing) was also added at a packing ratio of 30% (v / v).

[0079] The total hydraulic retention time (HRT) of the SBR reactor was set to 6 hours, including 5 minutes for influent, 5 hours for aeration and stirring, 30 minutes for sedimentation, 5 minutes for effluent, and 20 minutes for stagnation.

[0080] The influent was rural domestic sewage, with the following components: 138 mg / L COD and 24.8 mg / L NH4. + -N, 2.2 mg / L PO4 3- -P, TP 2.6mg / L, TN 38.43mg / L, NO3 - -N 0.54mg / L, NO2 - -N 0.032mg / L.

[0081] The operating parameters for the following reactors are as follows:

[0082] The reactor was operated for 4 weeks. The concentration of the signaling molecule C6-HSL added to the influent (rural domestic sewage) was 10–100 nmol / L. During reactor operation, the concentration of suspended sludge was reduced by sludge removal every week until the final week when the reactor operated in pure membrane mode. Specific operational procedures during reactor operation are as follows:

[0083] During the first week of reactor operation, the concentration of activated sludge in the reactor was 3000 mg / L, and the content of the signal molecule C6-HSL added to the influent was 10 nmol / L.

[0084] In the second week of reactor operation, sludge was removed to bring the activated sludge concentration in the reactor to 2000 mg / L and the content of the signal molecule C6-HSL added to the influent to 30 nmol / L.

[0085] In the third week of reactor operation, sludge was removed to bring the activated sludge concentration in the reactor to 1000 mg / L and the content of the signal molecule C6-HSL added to the influent to 50 nmol / L.

[0086] In the fourth week of reactor operation, sludge was removed to bring the activated sludge concentration in the reactor to 0 mg / L, and the content of the signal molecule C6-HSL added to the influent to 100 nmol / L.

[0087] Finally, a reactor operating with pure membrane technology was obtained.

[0088] Four weeks later, the reactor was put into operation, with rural domestic sewage as the influent, consisting of 138 mg / L COD and 24.8 mg / L NH4. + -N, 2.2 mg / L PO4 3- -P, TP 2.6mg / L, TN 38.43mg / L, NO3 - -N 0.54mg / L, NO2 - -N 0.032 mg / L;

[0089] The reactor operating parameters are:

[0090] The influent time is 5 minutes; the aeration and stirring time is 300 minutes; the sedimentation time is 30 minutes; the effluent time is 5 minutes; and the stagnation period is 20 minutes.

[0091] After the water is extracted, the wastewater is tested for COD, ammonia nitrogen, total nitrogen removal rate, and biofilm thickness.

[0092] The test results showed that the COD removal rate was 99.6%, the ammonia nitrogen removal rate was 94.2%, the total nitrogen removal rate was 80%, and the biofilm thickness was 190 μm.

[0093] Example 2: Using different rural domestic sewage

[0094] The specific implementation method is the same as in Example 1, except that the rural domestic sewage is adjusted to have the following composition: 117.5 mg / L LOD and 62.3 mg / L NH4. + -N, 1.2 mg / L PO4 3--P, TP 1.75mg / L, TN 75.6mg / L, NO3 - -N 0.22mg / L, NO2 - -N 0.06 mg / L

[0095] After the water is extracted, the wastewater is tested for COD, ammonia nitrogen, total nitrogen removal rate, and biofilm thickness.

[0096] The test results showed that the COD removal rate was 98.4%, the ammonia nitrogen removal rate was 92.6%, and the total nitrogen removal rate was 79.4%.

[0097] Example 3: Using different rural domestic sewage

[0098] The specific implementation method is the same as in Example 1, except that the rural domestic sewage is adjusted to have the following composition: 121.4 mg / L LOD and 64.8 mg / L NH4. + -N, 2.4 mg / L PO4 3- -P, TP 3.2mg / L, TN 78.43mg / L, NO3 - -N 0.32mg / L, NO2 - -N 0.017 mg / L

[0099] After the water is extracted, the wastewater is tested for COD, ammonia nitrogen, total nitrogen removal rate, and biofilm thickness.

[0100] The test results showed that the COD removal rate was 98.6%, the ammonia nitrogen removal rate was 93.2%, and the total nitrogen removal rate was 78.1%.

[0101] Comparative Example 1: Using other signaling molecules

[0102] The specific implementation method is the same as in Example 1, except that the signal molecule C6-HSL is adjusted to C4-HSL or C8-HSL.

[0103] The remaining steps are the same as in Example 1, and the results are as follows:

[0104] When the signal molecule was C4-HSL, the COD removal rate was 65.6%, the ammonia nitrogen removal rate was 78.2%, the total nitrogen removal rate was 65.3%, and the biofilm thickness was 82 μm.

[0105] When the signal molecule was C8-HSL, the COD removal rate was 71.6%, the ammonia nitrogen removal rate was 69.5%, the total nitrogen removal rate was 60.8%, and the biofilm thickness was 78 μm.

[0106] Comparative Example 2: Changing the method of signal molecule administration

[0107] 1. The specific implementation method is the same as in Example 1, except that the concentration of the signal molecule added to the influent (rural domestic sewage) is adjusted to be constant at 10 nmol / L, that is, the operation during reactor operation is adjusted as follows:

[0108] The reactor was operated for 4 weeks. The concentration of the signaling molecule C6-HSL added to the influent (rural domestic sewage) was 10 nmol / L. During reactor operation, the concentration of suspended sludge was reduced by sludge removal every week until the final week when the reactor operated in pure membrane mode. Specific operational procedures during reactor operation are as follows:

[0109] During the first week of reactor operation, the concentration of activated sludge in the reactor was 3000 mg / L, and the content of the signal molecule C6-HSL added to the influent was 10 nmol / L.

[0110] In the second week of reactor operation, sludge was removed to bring the activated sludge concentration in the reactor to 2000 mg / L and the content of the signal molecule C6-HSL added to the influent to 10 nmol / L.

[0111] In the third week of reactor operation, sludge was removed to bring the activated sludge concentration in the reactor to 1000 mg / L and the content of the signal molecule C6-HSL added to the influent to 10 nmol / L.

[0112] In the fourth week of reactor operation, sludge was removed to bring the activated sludge concentration in the reactor to 0 mg / L, and the concentration of the signaling molecule C6-HSL added to the influent to 10 nmol / L. The remaining steps were the same as in Example 1, and the results are as follows:

[0113] The test results showed that the COD removal rate was 74.6%, the ammonia nitrogen removal rate was 71.7%, the total nitrogen removal rate was 65%, and the biofilm thickness was 60 μm.

[0114] 2. The specific implementation method is the same as in Example 1, except that the concentration of the signal molecule added to the influent (rural domestic sewage) is adjusted to be constant at 30 nmol / L, that is, the operation during reactor operation is adjusted as follows:

[0115] The reactor was operated for 4 weeks. The concentration of the signaling molecule C6-HSL added to the influent (rural domestic sewage) was 30 nmol / L. During reactor operation, the concentration of suspended sludge was reduced by sludge removal every week until the final week when the reactor operated in pure membrane mode. Specific operational procedures during reactor operation are as follows:

[0116] During the first week of reactor operation, the concentration of activated sludge in the reactor was 3000 mg / L, and the content of the signal molecule C6-HSL added to the influent was 30 nmol / L.

[0117] In the second week of reactor operation, sludge was removed to bring the activated sludge concentration in the reactor to 2000 mg / L and the content of the signal molecule C6-HSL added to the influent to 30 nmol / L.

[0118] In the third week of reactor operation, sludge was removed to bring the activated sludge concentration in the reactor to 1000 mg / L and the content of the signal molecule C6-HSL added to the influent to 30 nmol / L.

[0119] In the fourth week of reactor operation, sludge was removed to bring the activated sludge concentration in the reactor to 0 mg / L, and the content of the signal molecule C6-HSL added to the influent to 30 nmol / L.

[0120] The remaining steps are the same as in Example 1, and the results are as follows:

[0121] The test results showed that the COD removal rate was 76.2%, the ammonia nitrogen removal rate was 73.1%, the total nitrogen removal rate was 67.2%, and the biofilm thickness was 65 μm.

[0122] 3. The specific implementation method is the same as in Example 1, except that the concentration of the signal molecule added to the influent (rural domestic sewage) is adjusted to be constant at 50 nmol / L, that is, the operation during reactor operation is adjusted as follows:

[0123] The reactor was operated for 4 weeks. The concentration of the signaling molecule C6-HSL added to the influent (rural domestic sewage) was 50 nmol / L. During reactor operation, the concentration of suspended sludge was reduced by sludge removal every week until the final week when the reactor operated in pure membrane mode. Specific operational procedures during reactor operation are as follows:

[0124] During the first week of reactor operation, the concentration of activated sludge in the reactor was 3000 mg / L, and the content of the signal molecule C6-HSL added to the influent was 50 nmol / L.

[0125] In the second week of reactor operation, sludge was removed to bring the activated sludge concentration in the reactor to 2000 mg / L and the content of the signal molecule C6-HSL added to the influent to 50 nmol / L.

[0126] In the third week of reactor operation, sludge was removed to bring the activated sludge concentration in the reactor to 1000 mg / L and the content of the signal molecule C6-HSL added to the influent to 50 nmol / L.

[0127] In the fourth week of reactor operation, sludge was removed to bring the activated sludge concentration in the reactor to 0 mg / L, and the concentration of the signaling molecule C6-HSL added to the influent to 50 nmol / L.

[0128] The remaining steps are the same as in Example 1, and the results are as follows:

[0129] The test results showed that the COD removal rate was 78.4%, the ammonia nitrogen removal rate was 74.7%, the total nitrogen removal rate was 68.3%, and the biofilm thickness was 67 μm.

[0130] 4. The specific implementation method is the same as in Example 1, except that the concentration of the signal molecule added to the influent (rural domestic sewage) is adjusted to be constant at 100 nmol / L, that is, the operation during reactor operation is adjusted as follows:

[0131] The reactor was operated for 4 weeks. The concentration of the signaling molecule C6-HSL added to the influent (rural domestic sewage) was 100 nmol / L. During reactor operation, the concentration of suspended sludge was reduced by sludge removal every week until the final week when the reactor operated in pure membrane mode. Specific operational procedures during reactor operation are as follows:

[0132] During the first week of reactor operation, the concentration of activated sludge in the reactor was 3000 mg / L, and the content of the signal molecule C6-HSL added to the influent was 100 nmol / L.

[0133] In the second week of reactor operation, sludge was removed to bring the activated sludge concentration in the reactor to 2000 mg / L and the content of the signal molecule C6-HSL added to the influent to 100 nmol / L.

[0134] In the third week of reactor operation, sludge was removed to bring the activated sludge concentration in the reactor to 1000 mg / L and the content of the signal molecule C6-HSL added to the influent to 100 nmol / L.

[0135] In the fourth week of reactor operation, sludge was removed to bring the activated sludge concentration in the reactor to 0 mg / L, and the content of the signal molecule C6-HSL added to the influent to 100 nmol / L.

[0136] The remaining steps are the same as in Example 1, and the results are as follows:

[0137] The test results showed that the COD removal rate was 80.6%, the ammonia nitrogen removal rate was 77.1%, the total nitrogen removal rate was 70.9%, and the biofilm thickness was 75 μm.

[0138] Comparative Example 3: No signaling molecule C6-HSL added

[0139] The specific implementation method is the same as in Example 1, except that the signaling molecule C6-HSL is not added to the influent, that is, the operation during reactor operation is adjusted as follows:

[0140] The reactor was operated for 4 weeks. During operation, the concentration of suspended sludge was reduced weekly by sludge removal. The specific operational procedures during reactor operation were as follows:

[0141] During the first week of reactor operation, the concentration of activated sludge in the reactor was 3000 mg / L.

[0142] In the second week of reactor operation, sludge was removed to bring the activated sludge concentration in the reactor to 2000 mg / L.

[0143] In the third week of reactor operation, sludge was removed to bring the activated sludge concentration in the reactor to 1000 mg / L.

[0144] In the fourth week of reactor operation, sludge was removed to bring the concentration of activated sludge in the reactor to 0 mg / L.

[0145] The remaining steps are the same as in Example 1, and the results are as follows:

[0146] The test results showed that the COD removal rate was 65.2%, the ammonia nitrogen removal rate was 71.3%, the total nitrogen removal rate was 62.4%, and the biofilm thickness was 93 μm.

[0147] Comparative Example 4: No filler added

[0148] The specific implementation method is the same as in Example 1, except that MBBR suspension packing is not added in step (2), that is, the "and MBBR suspension packing (K3 packing) is added, and the MBBR packing filling ratio is 30% (v / v)" in Example 1 is deleted.

[0149] The remaining steps are the same as in Example 1, and the results are as follows:

[0150] The test results showed that the COD removal rate was 82.1%, the ammonia nitrogen removal rate was 70.6%, and the total nitrogen removal rate was 59.8%.

[0151] Comparative Example 5: Changing the type of feed

[0152] 1. The specific implementation method is the same as in Example 1, except that the MBBR suspension packing (K3 packing) is changed to MBBR suspension packing (K5 packing).

[0153] The remaining steps are the same as in Example 1, and the results are as follows:

[0154] The test results showed that the COD removal rate was 85.3%, the ammonia nitrogen removal rate was 80.1%, the total nitrogen removal rate was 70.6%, and the biofilm thickness was 100 μm.

[0155] 2. The specific implementation method is the same as in Example 1, except that the MBBR suspension packing (K3 packing) is changed to MBBR suspension packing (K7 packing).

[0156] The remaining steps are the same as in Example 1, and the results are as follows:

[0157] The test results showed that the COD removal rate was 81.2%, the ammonia nitrogen removal rate was 74.8%, the total nitrogen removal rate was 65.1%, and the biofilm thickness was 88 μm.

[0158] Comparative Example 6: Changing the sludge addition method

[0159] The specific implementation method is the same as in Example 1, except that the suspended sludge concentration is maintained at MLSS = 3000 mg / L, that is, the operation during reactor operation is adjusted as follows:

[0160] The reactor was operated for 4 weeks. The concentration of the signaling molecule C6-HSL added to the influent (rural domestic sewage) was 10–100 nmol / L. During reactor operation, the suspended sludge concentration was maintained at MLSS = 3000 mg / L. Specific operational procedures during reactor operation were as follows:

[0161] During the first week of reactor operation, the concentration of activated sludge in the reactor was 3000 mg / L, and the content of the signal molecule C6-HSL added to the influent was 10 nmol / L.

[0162] In the second week of reactor operation, sludge was removed to bring the activated sludge concentration in the reactor to 3000 mg / L and the content of the signal molecule C6-HSL added to the influent to 30 nmol / L.

[0163] In the third week of reactor operation, sludge was removed to bring the activated sludge concentration in the reactor to 3000 mg / L and the content of the signal molecule C6-HSL added to the influent to 50 nmol / L.

[0164] In the fourth week of reactor operation, sludge was removed to bring the activated sludge concentration in the reactor to 3000 mg / L, and the content of the signal molecule C6-HSL added to the influent to 100 nmol / L.

[0165] The remaining steps are the same as in Example 1, and the results are as follows:

[0166] The test results showed that the COD removal rate was 81.6%, the ammonia nitrogen removal rate was 74.1%, the total nitrogen removal rate was 65.3%, and the biofilm thickness was 65 μm.

[0167] The results in this study indicate that the 190 μm biofilm in Example 1 was more mature than that in the comparative example. Biofilm thickness is generally closely related to the number and activity of microorganisms, as well as the reactor's processing capacity. A thicker biofilm provides more surface area, supporting greater microbial attachment and metabolic activity, especially in the degradation of organic matter and nitrogen. Generally, a thicker biofilm also indicates a stronger processing capacity. The thinner biofilm in the comparative example resulted in a weaker number of microorganisms and lower degradation capacity, affecting the removal efficiency of COD, ammonia nitrogen, and total nitrogen. Example 1's COD removal rate of 99.6% was significantly higher than the comparative example, and its ammonia nitrogen removal rate of 94.2% was also higher. In Example 1, due to the more mature biofilm and the stronger number and activity of nitrifying bacteria, ammonia nitrogen removal was achieved more efficiently. The total nitrogen removal rate of 80% was higher than the comparative example. Total nitrogen removal involves both ammonia nitrogen nitrification and nitrate denitrification. The biofilm in Example 1 not only has a strong nitrification capacity but also promotes the growth and activity of denitrifying bacteria, which helps to further reduce the total nitrogen concentration. In contrast, the biofilm in the comparative example may not be able to support a sufficient denitrification process, resulting in a lower total nitrogen removal efficiency.

[0168] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A method for promoting biofilm formation on packing materials, characterized in that, The method includes: The reactor was inoculated with activated sludge from an aerobic tank and MBBR suspended packing was added. Wastewater was added to the reactor, and the signaling molecule C6-HSL was added during the reaction. The biofilm packing was obtained after the reactor had been running for four weeks. The operating reactor includes influent, aeration and stirring, sedimentation, effluent, and stagnation. During the first week, maintain the activated sludge concentration at 2800-3500 mg / L and add 1-10 nmol / L of the signaling molecule C6-HSL. In the second week, maintain the activated sludge concentration at 1500-2500 mg / L and add 20-40 nmol / L of the signaling molecule C6-HSL. In the third week, maintain the activated sludge concentration at 500-1500 mg / L and add 40-60 nmol / L of the signaling molecule C6-HSL. In the fourth week, maintain the activated sludge concentration at 0 mg / L and add 90-110 nmol / L of the signaling molecule C6-HSL. The MBBR suspension packing is K3 packing; The wastewater is rural domestic sewage, and its components include 100-300 mg / L COD and 20-100 mg / L NH4. + -N, 1-20 mg / LPO4 3- -P, 1-20 mg / L TP, 20-150mg / L TN, 0-20 mg / L NO3 - -N, 0-10 mg / L NO2 - -N.

2. The method according to claim 1, characterized in that, When operating the reactor, the influent time is 5-10 min; the aeration and stirring time is 280-350 min; the sedimentation time is 25-60 min; the effluent time is 5-10 min; and the stagnation period is 15-30 min.

3. The method according to claim 1, characterized in that, The inoculum amount (MLSS) of activated sludge in the aerobic tank is 2800-3500 mg / L.

4. The method according to claim 3, characterized in that, The inoculum amount (MLSS) of activated sludge in the aerobic tank was 3000 mg / L.

5. The method according to claim 1, characterized in that, The addition amount of MBBR suspension packing is 20%-50% v / v.

6. The method according to claim 5, characterized in that, The MBBR suspension packing is added at a rate of 30% v / v.

7. A method for simultaneously improving the removal rates of COD, ammonia nitrogen, and total nitrogen in wastewater, characterized in that, Wastewater is treated using a reactor operating purely on membrane technology; the method for preparing the reactor is as follows: The reactor was inoculated with activated sludge from an aerobic tank and MBBR suspended packing was added. Wastewater was added to the reactor, and the signaling molecule C6-HSL was added during the reaction. After running the reactor for four weeks, a reactor operating purely on membranes was obtained. The operating reactor includes influent, aeration and stirring, sedimentation, effluent, and stagnation. During the first week, maintain the activated sludge concentration at 2800-3500 mg / L and add 0-10 nmol / L of the signaling molecule C6-HSL. In the second week, maintain the activated sludge concentration at 1500-2500 mg / L and add 20-40 nmol / L of the signaling molecule C6-HSL. In the third week, maintain the activated sludge concentration at 500-1500 mg / L and add 40-60 nmol / L of the signaling molecule C6-HSL. In the fourth week, maintain the activated sludge concentration at 0 mg / L and add 90-110 nmol / L of the signaling molecule C6-HSL. The MBBR suspension packing is K3 packing; The wastewater is rural domestic sewage, and its components include 100-300 mg / L COD and 20-100 mg / L NH4. + -N, 1-20 mg / LPO4 3- -P, 1-20 mg / L TP, 20-150mg / L TN, 0-20 mg / L NO3 - -N, 0-10 mg / L NO2 - -N.

8. The method according to claim 1, characterized in that, When operating the reactor, the influent time is 5-10 min; the aeration and stirring time is 280-350 min; the sedimentation time is 25-60 min; the effluent time is 5-10 min; and the stagnation period is 15-30 min.

9. The method according to claim 1, characterized in that, The inoculum amount of activated sludge in the aerobic tank is 2800-3500 mg / L (MLSS); the amount of MBBR suspended packing added is 20%-50% v / v.

10. The method according to claim 9, characterized in that, The inoculum amount of activated sludge in the aerobic tank was 3000 mg / L (MLSS); the amount of MBBR suspended packing added was 30% v / v.

11. The application of the method according to any one of claims 1 to 10 in wastewater treatment.

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