A biological sewage treatment method for improving nitrification performance at low temperatures

Abstract

The application provides a sewage biological treatment method for improving nitrification performance at low temperature, and belongs to the technical field of sewage treatment. The sewage biological treatment method comprises: sequentially performing start-up stage treatment and mature stage treatment under the condition of a temperature of ≤12℃; in the start-up stage treatment, N-butyryl-L-homoserine lactone is added to a to-be-treated system once every operation cycle; in the mature stage treatment, when the influent NH4 + -N concentration is ≤80 mg / L, the addition of N-butyryl-L-homoserine lactone is stopped; when the influent NH4 + -N concentration is >80 mg / L, N-butyryl-L-homoserine lactone is added to the to-be-treated system once every 1-3 operation cycles. The method adds N-butyryl-L-homoserine lactone signal molecules to improve the nitrification performance of the biological treatment system, different addition modes are adopted according to different influent NH4 + -N concentrations, and the method has good biological treatment effect and economy.

Description

Technical Field

[0001] This application relates to the field of wastewater treatment technology, and more specifically, to a biological wastewater treatment method that improves nitrification performance at low temperatures. Background Technology

[0002] Biological wastewater treatment technology is widely used in urban and rural domestic wastewater treatment due to its advantages such as high removal efficiency, low operating costs, and convenient operation and management. Temperature is one of the important factors affecting the activity of microorganisms and the treatment effect in the biological wastewater treatment process. Low temperatures reduce the activity of microorganisms (especially nitrifying bacteria), leading to insufficient nitrification capacity of the biological treatment system and ultimately affecting the nitrogen removal efficiency. The average temperature in northern Chinese cities is 5-8℃, and the NH4+ levels in Northwest, Northeast, and North China are relatively high. + -N removal efficiency is lower than the national average. Furthermore, based on the operational data of 20 municipal wastewater treatment plants in Northeast China from 2011 to 2018, it was found that NH4+ removal efficiency is lower than the national average. + -N frequently exceeds emission limits in winter, and total nitrogen in the effluent increases with NH4+. + The -N fluctuation indicates that the nitration process is sensitive to low temperatures.

[0003] Currently, technical solutions for improving the nitrification performance of biological treatment systems at low temperatures mainly include equipment modification and bioaugmentation through inoculation with cryogenic functional bacteria. On the one hand, modifying existing wastewater treatment plant equipment is costly and inconvenient to operate; on the other hand, the screening process for cryogenic functional bacteria is complex and difficult, requires a long acclimatization time, and the inoculated bacterial agents may compete with native bacteria in the reactor. These drawbacks reduce their practical application value. Summary of the Invention

[0004] The purpose of this application is to provide a wastewater biological treatment method that improves nitrification performance at low temperatures. This method utilizes exogenous N-butyryl-L-homoserine lactone (C4-HSL) signaling molecules to enhance the nitrification performance of the biological treatment system. Compared to modifying wastewater treatment plant equipment, this method reduces costs and allows for faster operation compared to inoculating functional bacteria. Furthermore, the C4-HSL signaling molecule is less expensive than other N-acylhomoserine lactone (AHL) signaling molecules and is effective against different influent NH4 levels. + Using different signal molecule addition methods, the -N concentration exhibits good biological treatment effects and economic efficiency.

[0005] The embodiments of this application are implemented as follows:

[0006] This application provides a wastewater biological treatment method to improve nitrification performance at low temperatures, comprising: performing a start-up stage treatment and a maturity stage treatment sequentially at a temperature of ≤12℃;

[0007] During the start-up phase, N-butyryl-L-homoserine lactone is added to the system to be treated once per operating cycle;

[0008] During the mature stage of treatment, when the influent NH4 + Stop adding N-butyryl-L-homoserine lactone when the N concentration is ≤80 mg / L, and stop adding it when the influent NH4+. + When the N-N concentration is >80 mg / L, N-butyryl-L-homoserine lactone should be added to the system to be treated once every 1 to 3 operating cycles.

[0009] The wastewater biological treatment method for improving nitrification performance at low temperatures provided in this application embodiment has at least the following beneficial effects:

[0010] 1. Utilizing exogenous C4-HSL signaling molecules to improve the nitrification performance of biological treatment systems can reduce costs compared to modifying wastewater treatment plant equipment, and can operate more quickly compared to inoculating functional bacteria.

[0011] 2. Currently, most methods for rapid start-up and treatment effects of bioreactors at low temperatures use long-chain mixed AHLs signaling molecules. However, these AHLs signaling molecules have disadvantages such as poor water solubility, the need to store them at -20°C, and high cost. In contrast, the C4-HSL signaling molecules used in this application are easier to store, have lower raw material costs, and are easier to dissolve and handle, thus having higher practical application value and economic efficiency.

[0012] 3. Current technologies for adding signaling molecules all involve continuous addition, further increasing application costs; the technical solution in this application, at the mature stage, involves adding signaling molecules based on the influent NH4... + Different signal molecule administration methods are used depending on the -N concentration. In some cases, the administration of signal molecules can be stopped or the administration of signal molecules can be done at appropriate intervals, which helps to further reduce the cost of signal molecules and has better economic efficiency.

[0013] 4. In the technical solution of this application, signaling molecules are continuously added during the start-up phase to optimize the community structure of microorganisms in the biological treatment system, enhance interspecific cooperation among functional bacteria, and improve the nitrification performance of the biological treatment system at low temperatures; moreover, this effect is long-term, and it is effective even in the influent NH4+. + When the -N concentration is below 80 mg / L, the nitrification performance can still be maintained even after the addition of signal molecules is stopped.

[0014] 5. In the technical solution of this application, at the mature stage, based on the influent NH4 +Different N-N concentrations, achieved through different signal molecule addition methods, can better regulate the abundance of nitrifying bacteria, microbial functional enzyme activity, quorum sensing genes, and energy metabolism-related genes in the biological treatment system, thus enabling the regulation of different influent NH4 levels. + It exhibits good low-temperature nitrification performance even at -N concentrations.

[0015] In some implementations, the temperature condition is ≤9°C; alternatively, the temperature condition is 6±1°C.

[0016] In some implementation schemes, a fixed biofilm activated sludge process is used for wastewater treatment.

[0017] In some implementations, each operating cycle satisfies one or more of the following conditions (a) to (d);

[0018] (a) The carrier filling rate of the reactor is 20-40%;

[0019] (b) The sludge concentration is 1500±500 mg / L;

[0020] (c) Duration is 8±4h;

[0021] (d) The drainage ratio is 50 ± 5%.

[0022] In some implementation schemes, during the start-up phase treatment, the influent NH4 + -N concentration ≤ 40 mg / L and / or number of operating cycles 40 to 80.

[0023] In some implementations, the initiation phase treatment continues until a biofilm is clearly attached to the carrier.

[0024] In some implementations, during the start-up phase treatment, the concentration of N-butyryl-L-homoserine lactone in the system to be treated is 20–100 μg / L each time it is added.

[0025] In some implementation schemes, during the maturity stage treatment, when the influent NH4 + When the N-N concentration is >80 mg / L, N-butyryl-L-homoserine lactone should be added to the system to be treated once every 2 to 3 operating cycles.

[0026] In some implementation schemes, during the maturation stage treatment, the concentration of N-butyryl-L-homoserine lactone in the system to be treated is 20–40 μg / L each time it is added.

[0027] In some implementations, during the start-up and maturation phases, the concentration of N-butyryl-L-homoserine lactone in the treatment system is the same each time it is added. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0029] It should be noted that the terms "and / or" in this application, such as "feature 1 and / or feature 2", all refer to the three cases of "feature 1" alone, "feature 2" alone, and "feature 1" plus "feature 2".

[0030] In addition, in the description of this application, unless otherwise stated, "one or more" means two or more; the range of "numerical value a to numerical value b" includes the two endpoints "a" and "b"; and "unit of measurement" in "numerical value a to numerical value b + unit of measurement" represents the "unit of measurement" of both "numerical value a" and "numerical value b".

[0031] The technical solutions of the embodiments of this application are described below by way of example.

[0032] This application provides a wastewater biological treatment method to improve nitrification performance at low temperatures, comprising: performing a start-up stage treatment and a maturity stage treatment sequentially at a temperature of ≤12℃.

[0033] During the start-up phase, N-butyryl-L-homoserine lactone is added to the system to be treated once per operating cycle.

[0034] During the mature stage of treatment, when the influent NH4 + Stop adding N-butyryl-L-homoserine lactone when the N concentration is ≤80 mg / L, and stop adding it when the influent NH4+. + When the N-N concentration is >80 mg / L, N-butyryl-L-homoserine lactone should be added to the system to be treated once every 1 to 3 operating cycles.

[0035] It should be noted that the wastewater biological treatment method in the embodiments of this application is not limited to any particular method, such as, but not limited to, one of the broadly defined activated sludge process and biofilm process. As an example, an immobilized biofilm activated sludge process (IFAS) is used for wastewater treatment. IFAS technology is a sludge-film composite system that combines the advantages of both the activated sludge process and the biofilm process.

[0036] Specifically, the essence of IFAS technology lies in adding biological carriers to activated sludge, thus forming a composite treatment system that includes both fixed biofilm and suspended activated sludge, fully leveraging the advantages of both microbial forms to ultimately achieve the goal of highly efficient pollutant removal. The introduction of biological carriers significantly increases the biomass within the system, while the sludge loading rate decreases and the sludge age increases under constant influent load, which is conducive to the growth of nitrifying bacteria on the carrier, ensuring good nitrification performance. Furthermore, the biological carriers can firmly fix filamentous bacteria to their surface, which not only avoids system damage caused by sludge bulking and improves the system's operational stability, but also allows the powerful purification capacity of filamentous bacteria to enhance the system's treatment efficiency.

[0037] Generally, the IFAS process has a long start-up time, especially under low-temperature conditions. Biofilms formed at low temperatures are unstable and easily detach, resulting in high suspended solids content in the effluent. Research has found that the surge in biofilm during IFAS start-up is caused by quorum sensing (QS) among microorganisms. Therefore, regulating QS among bacterial communities may accelerate bacterial attachment to carrier surfaces. QS is an intercellular signaling mechanism that releases signaling molecules to the external environment, activating downstream target genes and thus regulating bacterial physiological behavior. In the implementation scheme of this application, C4-HSL signaling molecules are used to intervene in the quorum sensing phenomenon among microorganisms, optimizing the microbial community structure within the system and stimulating quorum sensing. Combined with the IFAS process, this provides a more economical and efficient biological treatment technology for low-temperature domestic wastewater.

[0038] In the embodiments of this application, the temperature conditions are, for example, but not limited to, any one of 4°C, 5°C, 6°C, 7°C, 8°C, 9°C, 10°C, 11°C, and 12°C, or a range between any two. Studies have shown that wastewater biological treatment under the above temperature conditions exhibits good nitrification performance.

[0039] As an example, the temperature condition is ≤9℃. Optionally, the temperature condition is 4℃≤9℃. Further optional, the temperature condition is 6±1℃, which is close to the average water temperature in winter and can better realize the application transformation.

[0040] It is understood that, in the embodiments of this application, an operating cycle refers to a cyclic treatment unit in the biological treatment of wastewater, which includes operations such as, but not limited to, influent, aeration, settling, and drainage.

[0041] In some implementations, each operating cycle meets one or more of the following conditions (a) to (d): (a) the reactor carrier filling rate is 20% to 40%; (b) the sludge concentration is 1500±500 mg / L; (c) the duration is 8±4 h; and (d) the effluent ratio is 50±5%.

[0042] For example, the reactor has a carrier filling rate of 30%.

[0043] For example, the sludge concentration is 1500 mg / L.

[0044] As an example, in a fixed biofilm activated sludge process, each operating cycle includes sequential influent, aeration, settling, and effluent discharge. Influent for the next operating cycle begins after effluent discharge from the previous cycle. The addition of C4-HSL signaling molecules is performed during the influent stage.

[0045] For example, the water intake stage lasts for 5 minutes, the aeration stage lasts for 6 hours, the settling stage lasts for 1.5 hours, and the drainage stage lasts for 25 minutes.

[0046] For example, the drainage ratio is 50%.

[0047] It should be noted that in this application, regarding the addition of signal molecules, continuous addition means that the addition is carried out during the water intake phase of each operating cycle, not that the addition action is continuous at all times. Correspondingly, intermittent addition means that there is an operating cycle in which no addition is carried out between two addition operations.

[0048] Regarding the start-up phase treatment, C4-HSL signal molecules are added to the system to be treated once in each operating cycle. In other words, C4-HSL signal molecules are added continuously during the start-up phase treatment.

[0049] Regarding the treatment of the mature stage, when the influent NH4 + When the -N concentration is >80 mg / L, C4-HSL signal molecules can be added to the system to be treated once every one operating cycle, that is, the C4-HSL signal molecules can be added continuously; or C4-HSL signal molecules can be added to the system to be treated once every two or three operating cycles, that is, the C4-HSL signal molecules can be added intermittently.

[0050] It should be noted that, in the embodiments of this application, the start-up phase treatment ends with the system reaching maturity, followed by the maturity phase treatment. System maturity is defined by, but is not limited to, indicators such as stable pollutant removal efficiency, strong resistance to shock loads, and significant biofilm adhesion on the carrier.

[0051] In some implementations, during the startup phase, the number of cycles in the operation cycle is 40 to 80. This number of cycles is, for example, but not limited to, any one of the following values ​​or a range between any two: 40, 45, 50, 55, 60, 65, 70, 75, and 80.

[0052] Taking the fixed biofilm activated sludge process as an example, in the initial stage of start-up treatment, the carrier in the reactor is an un-filmed carrier; after 40 operating cycles, a biofilm is clearly attached to the carrier, and the pollutant removal rate tends to stabilize; during the 41st to 80th operating cycles, the influent COD and NH4 are increased. + The concentration of -N was used to test the reactor's resistance to shock loads. It was found that the reactor with a certain concentration of C4-HSL had strong resistance to shock loads, fast biofilm attachment speed, and good nitrification performance.

[0053] In some implementation schemes, during the start-up phase treatment, the influent NH4 + -N concentration ≤ 40 mg / L, for example, but not limited to, any one of 20 mg / L, 25 mg / L, 30 mg / L, 35 mg / L, 40 mg / L, or a range between any two.

[0054] As an example, the start-up phase of the activated sludge process based on immobilized biofilm is carried out until the biofilm is clearly attached to the carrier.

[0055] Regarding the start-up treatment, optionally, each time N-butyryl-L-homoserine lactone is added, the concentration of N-butyryl-L-homoserine lactone in the system to be treated is 20–100 μg / L, for example, but not limited to any one of 20 μg / L, 30 μg / L, 40 μg / L, 50 μg / L, 60 μg / L, 70 μg / L, 80 μg / L, 90 μg / L, 100 μg / L or any range between two, which is conducive to rapid biofilm adhesion and can better improve the nitrification performance of the system.

[0056] Regarding the treatment of the mature stage, for example, when the influent NH4 + When the N-N concentration is >80 mg / L, N-butyryl-L-homoserine lactone is added to the system to be treated once every 2 to 3 operating cycles. The method of adding C4-HSL signal molecules at intervals is beneficial to further reduce the cost of signal molecules and has better economic efficiency.

[0057] Optionally, during the mature stage treatment, each time N-butyryl-L-homoserine lactone is added, the concentration of N-butyryl-L-homoserine lactone in the treatment system is 20–40 μg / L, for example, but not limited to any one of 20 μg / L, 30 μg / L, or 40 μg / L, or any range between two. Studies have found that in the influent NH4 + When the -N concentration is >80 mg / L, adding C4-HSL signaling molecules according to the above standard can better maintain the nitrification performance of the system.

[0058] For example, in the start-up and maturation stages, the concentration of N-butyryl-L-homoserine lactone in the treatment system is the same each time it is added, for example, 20 μg / L. Based on this technical solution, the same C4-HSL stock solution can be prepared and used throughout the entire process, and only the C4-HSL addition interval needs to be adjusted, making the operation simpler.

[0059] The features and performance of this application will be further described in detail below with reference to specific experimental examples.

[0060] I. Experimental Preparation

[0061] Biological treatment system: adopts IFAS process, the effective volume of IFAS reactor is 2L, the carrier filling rate of reactor is 30%, and the sludge concentration is 1500mg / L.

[0062] Inlet water composition: C6H 12 O6 0.2812 g / L (i.e., COD 300 mg / L), NH4Cl 0.1527~0.3817 g / L (i.e., NH4 + -N 40~100mg / L (adjust according to experimental conditions), KH2PO4 0.0132g / L (i.e. TP 3mg / L), NaHCO3 0.2~0.9g / L (adjust according to pH value), pH value maintained at 7~8, trace element stock solution 2mL / L.

[0063] Trace element stock solution: EDTA 0.38 mg / L, MgSO4·7H2O 0.4 mg / L, CaCl2 3.6 mg / L, FeSO4·7H2O 0.56 mg / L, MnCl2·4H2O 1.25 mg / L, ZnSO4·7H2O 0.55 mg / L, CoCl2·H2O 0.016 mg / L, H3BO3 0.006 mg / L, CuSO4·5H2O 0.4 mg / L, Na2MoO4·2H2O 0.5 mg / L.

[0064] C4-HSL stock solution: C4-HSL 10 mg / L.

[0065] II. Experimental Procedure

[0066] The reactor was placed in a constant temperature chamber at 6±1℃ and cultured for 8 hours per cycle (5 min of water inlet, 6 h of aeration, 1.5 h of settling, and 25 min of drainage) with a drainage ratio of 50%. The culture process is as follows, wherein the addition of C4-HSL was carried out along with the water inlet.

[0067] Start-up phase: In each operating cycle, each experimental group is given C4-HSL according to different concentration standards until 80 operating cycles have been cultured.

[0068] Maturation stage: C4-HSL was added to each experimental group according to different addition frequency standards and different addition concentration standards.

[0069] C4-HSL dosing conditions and influent NH4 in each experimental group during the start-up and maturity stages + -N concentration conditions are shown in Table 1.

[0070] Table 1. C4-HSL Dosing Conditions and NH4 + -N concentration conditions

[0071]

[0072] It should be noted that in each experimental group, different experiments started with the same initial phase, with NH4 entering the water. + -N concentration is 35 mg / L; different maturity stages are determined according to the influent NH4. + -N concentrations should be increased sequentially from low to high. Specifically, after completing the start-up phase, proceed according to the influent NH4 concentration. + The -N concentration was 40 mg / L, and the process was run for 62 cycles (taking experimental group 1 as an example, this corresponds to experimental group 1-1). Then, the influent NH4 was... + The -N concentration was increased to 60 mg / L and run for 60 cycles (taking experimental group 1 as an example, this corresponds to experimental groups 1-2). Then the influent NH4 was increased. + The -N concentration was increased to 80 mg / L and run for 120 cycles (taking experimental group 1 as an example, this corresponds to experimental groups 1-3). Then the influent NH4 was increased. + The -N concentration was increased to 100 mg / L and the operation continued (taking experimental group 1 as an example, this corresponds to experimental groups 1-4).

[0073] III. Experimental Results

[0074] 1. During the mature stage, collect the reactor effluent and test the pollutant removal effect.

[0075] Tests revealed that during the mature stage, none of the experimental groups required an adaptation period; the COD concentration in the reactor effluent could be reduced to below 50 mg / L, and the removal rate remained consistently around 90%.

[0076] The nitrification performance of each experimental group was statistically analyzed, and the results are shown in Table 2.

[0077] Table 2. Nitrification Performance

[0078]

[0079]

[0080]

[0081] It should be noted that in the test results, the average effluent concentration or average removal rate refers to the concentration of NH4 in the reactor. + The average value of the test results for all cycles after the removal effect of -N stabilized; with NH4 + Taking the experimental group where the -N concentration stabilized at 8 mg / L as an example, this was in the NH4+ group. + The average value of the test results for all cycles when the -N effluent concentration is consistently below 8 mg / L.

[0082] In addition, NH4Cl was used as the nitrogen source to simulate domestic sewage in each experimental group, and the amount of NH4Cl was determined according to the amount of NH4Cl used. + -N concentration calculation, but there is a weighing error in the preparation process, in the calculation of NH4 + When calculating the -N removal rate, use the actual measured NH4+. + The NH4+ concentration was calculated (influent and effluent concentrations). However, due to slight discrepancies between the actual and theoretical influent concentrations, the actual concentration was compared with the NH4+ concentration calculated using the theoretical influent concentration. + Compared to the NH4+ removal rate calculated based on the measured influent concentration in Table 2, the NH4+ removal rate is significantly higher. + -N removal rate may have slight deviations.

[0083] 2. During the mature stage, after the treatment effect stabilized, high-throughput sequencing was performed on the sludge and biofilm. The detection results are shown in Tables 3 to 5.

[0084] Table 3. Microbial Community

[0085]

[0086]

[0087] Table 4. Microbial functional enzyme activities

[0088]

[0089]

[0090]

[0091]

[0092] Table 5. Metagenomics Analysis

[0093]

[0094]

[0095]

[0096]

[0097]

[0098]

[0099]

[0100] The analysis based on Tables 1 to 5 is as follows:

[0101] Comparing experimental groups 1 and 3, it can be seen that in experimental group 1, C4-HSL was added for each operating cycle during the start-up phase, and the addition of C4-HSL was stopped during the maturity phase. When NH4 was introduced into the water... + When the -N concentration is ≤80 mg / L, the abundance of typical nitrifying bacteria such as Ellin6067, Nitrosomonas, and Candidatus Nitrotoga in the reactor increases. The activities of enzymes involved in nitrification, such as AMO, HAO, and NXR, as well as ATPase, which characterizes microbial activity, are all enhanced. Furthermore, the abundance of genes involved in the TCA cycle, such as sucAB and sucCD, as well as genes related to quorum sensing, such as autoinducer_producer, autoinducer, autoinducer_receptor, effector, and activator, is also increased. + -N concentration in the effluent can be stabilized relatively quickly below 8 mg / L, indicating good nitrification performance; when the influent NH4... + When the -N concentration is >80 mg / L, the AMO enzyme activity in both phases of the mud film is inhibited, thus affecting its ability to regulate NH4+. + -N removal effect, NH4 + The -N removal rate gradually decreases. By adding C4-HSL again at a higher frequency, the abundance of functional bacteria and functional genes in the mud film two-phase system is increased, and the activity of functional enzymes is improved, so that the nitrification performance of the reactor can be well restored.

[0102] Comparing experimental groups 2 and 3, it was found that in experimental group 2, adding C4-HSL during each operating cycle in the start-up phase and continuing to add C4-HSL every two operating cycles in the maturity phase increased the abundance of typical nitrifying bacteria such as Ellin6067, Nitrosomonas, and Candidatus Nitrotoga in the reactor. The activities of enzymes involved in nitrification, such as AMO, HAO, and NXR, as well as ATPase, which characterizes microbial activity, were all enhanced. Furthermore, it increased the abundance of genes involved in the TCA cycle, such as CS, acnAB, idh123, sucAB, sucCD, sdhABCD, and fumABC, as well as genes related to quorum sensing, such as autoinducer_producer, autoinducer, autoinducer_receptor, effector, activator, regulator, transporter, and decomposer. Under different influent NH4 levels... + At -N concentration, NH4 + -N concentrations in the effluent can be quickly stabilized below 8 mg / L, when the influent NH4... + When the -N concentration is >80 mg / L, no adaptation period is required for NH4+. + The -N concentration in the effluent is consistently below 8 mg / L, indicating good nitrification performance.

[0103] In experimental group 3, without the addition of C4-HSL, the abundance of functional bacteria and functional genes in the IFAS reactor was low, and the activity of functional enzymes was weak. When entering the maturation stage, the influent NH4... + When the -N concentration is 40 mg / L, the wastewater cannot meet the discharge standards under low temperature conditions; as the operating time increases, the reactor without C4-HSL is also gradually adapting to the low temperature environment, and the influent NH4 concentration is decreasing. + Even when the -N concentration is increased to 60–100 mg / L, a relatively long adaptation period is required to control NH4+. + The -N concentration in the effluent is consistently below 8 mg / L, indicating poor nitrification performance.

[0104] Comparing experimental group 4 and experimental group 2, it can be seen that in experimental group 4, C4-HSL was added at a lower frequency and with a longer interval during the maturation stage. When the influent NH4... + When the -N concentration is higher than 40 mg / L, the intermittent addition of C4-HSL will affect the quorum sensing effect, inhibit the activity of functional bacteria and functional enzymes, and reduce the abundance of functional genes, resulting in poor nitrification performance.

[0105] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. A wastewater biological treatment method for improving nitrification performance at low temperatures, characterized in that, include: Wastewater treatment was carried out using a fixed biofilm activated sludge process at a temperature of ≤12℃, with the start-up stage treatment and the maturity stage treatment performed sequentially. During the start-up phase, N-butyryl-L-homoserine lactone is added to the system to be treated once per operating cycle, and NH4 is introduced into the water. + -N concentration ≤ 40 mg / L, the number of operating cycles is 40~80; In the mature stage treatment, when the influent NH4 + When the N-butyryl-L-homoserine lactone concentration is ≤80 mg / L, the addition of the N-butyryl-L-homoserine lactone should be stopped, and the influent NH4 should be used as needed. + When the N-N concentration is >80 mg / L, the N-butyryl-L-homoserine lactone is added to the system to be treated once every 1 to 3 operating cycles.

2. The wastewater biological treatment method for improving nitrification performance at low temperatures according to claim 1, characterized in that, The temperature condition is ≤9℃.

3. The wastewater biological treatment method for improving nitrification performance at low temperatures according to claim 2, characterized in that, The temperature condition is 6±1℃.

4. The wastewater biological treatment method for improving nitrification performance at low temperatures according to claim 1, characterized in that, Each of the aforementioned operating cycles satisfies one or more of the following conditions (a) to (d); (a) The carrier filling rate of the reactor is 20-40%; (b) The sludge concentration is 1500±500 mg / L; (c) Duration is 8±4h; (d) The drainage ratio is 50±5%.

5. The wastewater biological treatment method for improving nitrification performance at low temperatures according to claim 1, characterized in that, The initiation phase is completed until a biofilm is clearly attached to the carrier.

6. The wastewater biological treatment method for improving nitrification performance at low temperatures according to claim 1, characterized in that, During the start-up phase, each time N-butyryl-L-homoserine lactone is added, the concentration of N-butyryl-L-homoserine lactone in the system to be treated is 20~100 μg / L.

7. A wastewater biological treatment method for improving nitrification performance at low temperatures according to any one of claims 1 to 4, characterized in that, In the mature stage treatment, when the influent NH4 + When the N-N concentration is >80 mg / L, the N-butyryl-L-homoserine lactone is added to the system to be treated once every 2 to 3 operating cycles.

8. The wastewater biological treatment method for improving nitrification performance at low temperatures according to claim 7, characterized in that, During the maturation stage treatment, each time N-butyryl-L-homoserine lactone is added, the concentration of N-butyryl-L-homoserine lactone in the system to be treated is 20~40 μg / L.

9. The wastewater biological treatment method for improving nitrification performance at low temperatures according to claim 8, characterized in that, In both the initiation and maturation stages, the concentration of N-butyryl-L-homoserine lactone in the treatment system remains the same each time it is added.

Images