A method for realizing short-range denitrification of suspended carrier biofilm

Abstract

The present invention discloses a method for realizing short-range denitrification of suspended carrier biofilm, which relates to the technical field of sewage. The method includes a startup phase, firstly, actual sewage is introduced into the anoxic zone of the pure membrane MBBR, with an initial flow rate of 10% of the design flow rate, until the nitrate nitrogen concentration in the effluent is ≤10 mg / L, and then the inlet flow rate is gradually increased to the design flow rate and the nitrate nitrogen concentration in the effluent is always guaranteed to be ≤10 mg / L; then, an acclimation phase is entered, the inlet flow rate and water quality are kept unchanged, and the nitrification liquid reflux ratio in the aerobic zone is gradually increased by 10% until the nitrous acid accumulation rate NAR in the anoxic zone is >80%; finally, a stable phase is entered. The present invention realizes a short-range denitrification process based on a pure biofilm method, with specialized bacterial flora cultivation, eliminating the problem of short-range instability caused by the circulation of the activated sludge multifunctional zone, making the operation control more stable, and the short-range denitrification load can reach 0.6 kgN / m 3 / d.

Description

Technical Field

[0001] The invention relates to the technical field of sewage, and in particular to a method for realizing short-range denitrification of suspended carrier biofilm. Background Art

[0002] One of the core aspects of sewage treatment is to achieve stable denitrification. The traditional denitrification pathway relies on the nitrification-denitrification process, which requires the complete oxidation of ammonia nitrogen to nitrate and then reduction to nitrogen gas. This process not only consumes a large amount of oxygen and organic carbon sources, but also increases operating costs and complexity. The anaerobic ammonium oxidation process can directly react ammonia nitrogen and nitrous oxide to produce nitrogen gas to achieve denitrification. However, in the treatment of municipal sewage, the conventional process is difficult to achieve stable and high-rate nitrous oxide production, thus limiting the large-scale impact of anaerobic ammonium oxidation. Compared with the production of nitrous oxide by short-term nitrification, the process control of producing nitrous oxide by short-term denitrification is relatively simple and more stable, but it requires a balance between the nitrous oxide accumulation rate and the nitrous oxide production rate.

[0003] At present, in order to achieve a stable short-range denitrification process for mainstream municipal sewage, the existing technology-related research includes:

[0004] CN106477720A discloses a short-range denitrification reactor and a quick start method for a short-range denitrification process, which first inoculates denitrification sludge and requires the denitrification rate to be greater than 0.1 kg NO3 - -N / m 3 / d, and then use an online pH meter and automatic control system to adjust the dosage of the reagents, control the pH in the system to 8.0-9.5, and configure various carbon sources to ensure the C / N ratio, so as to achieve a short-term denitrification effect through continuous pH control. It also has the following technical problems: First, the use of pH and automatic control systems to form short-term denitrification requires a relatively high pH. For activated sludge systems, sludge circulates in different functional zones, and high pH is not conducive to the activity of other bacteria such as nitrifying bacteria. At the same time, pH fluctuations in other functional zones can easily cause the degradation of short-term denitrifying bacteria, destroying the short-term effect. Second, the use of activated sludge method has a low load, which will inevitably lead to an excessively large anoxic zone tank capacity, which conflicts with the current requirements of urban refined renewal construction and intensive new, modified and expanded sewage treatment plants.

[0005] CN110697905B discloses a device and method for rapidly cultivating short-term denitrifying bacteria and producing nitrous oxide using fermented sludge as a carbon source. The method involves mixing excess sludge and then introducing it into a sludge fermentation-coupled short-term denitrification reactor to complete sludge hydrolysis and acidification. Nitration liquid then enters the reactor to produce nitrous oxide. In the sludge fermentation-coupled short-term denitrification reactor, the sludge fermentation microorganisms first ferment the excess sludge into easily degradable organic matter, reducing sludge volume and providing a carbon source for short-term denitrification. After sludge fermentation is complete, short-term denitrification is achieved using the fermentation product as a carbon source. This method also has the following technical problems: First, the short-term denitrification effect of this method requires good sludge fermentation, which is relatively cumbersome to control. Furthermore, most sewage treatment plants lack the conditions for sludge fermentation, making engineering feasibility low. Second, this method still primarily relies on the activated sludge process, which makes it difficult to avoid inherent problems such as short-term instability, low load, and excessive land occupation caused by the activated sludge training flow.

[0006] It can be seen that the current short-term denitrification in the industry is mainly based on the activated sludge process, which makes it difficult to achieve high-load short-term denitrification effects; at the same time, many technologies are only suitable for specific types of sewage or treatment plants of a specific size, and are difficult to promote to a wider range of scenarios. Some advanced technologies are not conducive to large-scale promotion and application due to their high costs or complex operations.

[0007] This shows that the prior art needs to be further improved. Summary of the Invention

[0008] The purpose of the present invention is to provide a method for achieving short-range denitrification of suspended carrier biofilm, which can not only ensure a stable short-range denitrification effect, but also take into account high efficiency and simplicity, and provide a new technical idea for the sewage treatment industry.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] A method for achieving short-range denitrification of a suspended carrier biofilm, wherein the system used includes a pure membrane MBBR anoxic zone and an aerobic zone, and the method comprises the following steps in sequence:

[0011] S1, startup phase

[0012] Sewage is introduced into the anoxic zone of the pure membrane MBBR, and the flow of sewage is controlled to maintain the nitrate nitrogen concentration of the system effluent ≤10mg / L; at this time, the C / N ratio of the inlet water in the anoxic zone of the pure membrane MBBR is K0, 2≤K0≤4; the nitrification liquid reflux ratio of the aerobic zone is R0, and the denitrification load is>0.8kgN / m 3 / d, biofilm thickness>200μm, relative abundance of biofilm denitrifying bacteria>20%, pure membrane MBBR anoxic zone hydraulic retention time HRT<0.5h;

[0013] S2, domestication stage

[0014] Keep the sewage flow and water quality unchanged, and gradually increase the nitrification liquid return ratio R in the aerobic zone by 10% until the nitrous accumulation rate NAR in the anoxic zone of the pure membrane MBBR is greater than 80%, and the acclimation is completed;

[0015] S3, stable stage

[0016] Entering the stable operation stage, the C / N ratio of the influent in the anoxic zone of the pure membrane MBBR is K1, 1≤K1≤2, the nitrification liquid reflux ratio in the aerobic zone is R1, R1≤400%, and the nitrification load is >0.8kgN / m 3 / d, biofilm thickness>200μm, relative abundance of biofilm denitrifying bacteria>20%, pure membrane MBBR anoxic zone hydraulic retention time HRT<0.5h;

[0017] The nitrification liquid reflux ratio is dynamically adjusted to maintain the C / N ratio of the influent in the anoxic zone of the pure membrane MBBR at 1-2, and the nitrification liquid reflux ratio is ≤400%, thus achieving a stable short-range denitrification process, with a nitrous accumulation rate NAR>80% and a nitrite load>0.6kgN / m 3 / d, biofilm thickness>200μm, relative abundance of biofilm denitrifying bacteria>20%, and hydraulic retention time HRT of the anoxic zone of pure membrane MBBR<0.5h.

[0018] In the above-mentioned method for realizing short-range denitrification of suspended carrier biofilm, suspended carriers are added into the anoxic zone of the pure membrane MBBR, and the filling rate of the suspended carriers is greater than 50%.

[0019] The above method for realizing short-range denitrification of suspended carrier biofilm, wherein the effective specific surface area of ​​the suspended carrier is ≥800m 2 / m 3 , specific gravity is 1.01~1.05.

[0020] In the above-mentioned method for realizing short-range denitrification of suspended carrier biofilm, the MLSS of the anoxic zone of the pure membrane MBBR is less than 200 mg / L.

[0021] The above method for realizing short-range denitrification of suspended carrier biofilm is as follows: the pure membrane MBBR anoxic zone is equipped with a stirrer, and the stirring power density of the stirrer is greater than 7.5W / m 3 Pool content.

[0022] In the above-mentioned method for realizing short-range denitrification of suspended carrier biofilm, in the startup phase S1, sewage is first introduced into the anoxic zone of the pure membrane MBBR, and the initial flow rate of the sewage is controlled to be 10% of the design flow rate until the nitrate nitrogen concentration of the system effluent is ≤10mg / L;

[0023] When the nitrate-nitrogen concentration in the system effluent is ≤10mg / L, increase the sewage inlet flow rate to the design flow rate to keep the nitrate-nitrogen concentration in the system effluent ≤10mg / L.

[0024] Compared with the prior art, the present invention brings the following beneficial technical effects:

[0025] (1) The present invention proposes a method for realizing short-range denitrification of suspended carrier biofilm. The method realizes a short-range denitrification process based on a pure biofilm method, specifically cultivates the bacterial community, eliminates the short-range instability easily caused by the circulation of the activated sludge multifunctional zone, and makes the operation control more stable. The short-range denitrification load can reach 0.6 kgN / m 3 / d.

[0026] (2) Based on the regulation of the reflow ratio, a stable short-range denitrification effect is achieved under actual sewage conditions. The operation control is simple, does not interfere with the normal operating parameters of the project, and ensures the stability of operation.

[0027] (3) The use of pure biofilm method improves the short-range denitrification load of the system. The hydraulic retention time of the anoxic zone of the pure membrane MBBR is less than 0.5h, which can significantly reduce the land occupation. DETAILED DESCRIPTION

[0028] The present invention proposes a method for achieving short-range denitrification of suspended carrier biofilms. In order to make the advantages and technical solutions of the present invention clearer and more specific, the present invention will be further described below with reference to specific embodiments.

[0029] A method for achieving short-range denitrification of a suspended carrier biofilm, wherein the system used includes a pure membrane MBBR anoxic zone and an aerobic zone, and the method sequentially comprises the following steps:

[0030] S1, startup phase

[0031] First, introduce sewage into the anoxic zone of the pure membrane MBBR, and control the initial sewage flow rate to 10% of the design flow rate until the system effluent nitrate nitrogen concentration is ≤10mg / L, ensuring that the effluent is stable and meets high standards during the commissioning period;

[0032] When the nitrate-nitrogen concentration in the system effluent is ≤10mg / L, increase the sewage inlet flow rate to the design flow rate to maintain the nitrate-nitrogen concentration in the system effluent ≤10mg / L to ensure system stability.

[0033] At this time, the C / N ratio of the influent in the anoxic zone of the pure membrane MBBR is K0, 2≤K0≤4; the nitrification liquid reflux ratio in the aerobic zone is R0, and the denitrification load is >0.8kgN / m 3 / d, biofilm thickness>200μm, relative abundance of biofilm denitrifying bacteria>20%, pure membrane MBBR anoxic zone hydraulic retention time HRT<0.5h, achieving a significant reduction in land occupation;

[0034] S2, domestication stage

[0035] Keeping the wastewater flow and water quality unchanged, gradually increase the nitrification liquid recirculation ratio R in the aerobic zone by 10% until the nitrous accumulation rate NAR in the anoxic zone of the pure membrane MBBR is greater than 80%, and the acclimation is completed. The C / N ratio is controlled based on the recirculation ratio, without the need for adding external chemicals or changing the inlet flow rate, thus ensuring the stability of the system during the commissioning period;

[0036] S3, stable stage

[0037] Entering the stable operation stage, the C / N ratio of the influent in the anoxic zone of the pure membrane MBBR is K1, 1≤K1≤2, the nitrification liquid reflux ratio in the aerobic zone is R1, R1≤400%, and the nitrification load is >0.8kgN / m 3 / d, biofilm thickness>200μm, relative abundance of biofilm denitrifying bacteria>20%, pure membrane MBBR anoxic zone hydraulic retention time HRT<0.5h;

[0038] The nitrification liquid reflux ratio is dynamically adjusted to maintain the C / N ratio of the influent in the anoxic zone of the pure membrane MBBR at 1-2, and the nitrification liquid reflux ratio is less than 400%, thus achieving a stable short-range denitrification process, with a nitrous accumulation rate NAR>80% and a nitrite load>0.6kgN / m 3 / d, biofilm thickness>200μm, relative abundance of biofilm denitrifying bacteria>20%, and hydraulic retention time HRT of the anoxic zone of pure membrane MBBR<0.5h.

[0039] Furthermore, in the present invention, a suspended carrier is added to the anoxic zone of the pure membrane MBBR, the filler of the suspended carrier is greater than 50%, and the effective specific surface area of ​​the suspended carrier is ≥800m 2 / m 3 The specific gravity is 1.01-1.05, the MLSS of the pure membrane MBBR anoxic zone is less than 200 mg / L, the pure membrane MBBR anoxic zone is equipped with a stirrer, and the stirring power density of the stirrer is greater than 7.5 W / m 3 Pool content.

[0040] The present invention will be further described below with reference to specific embodiments.

[0041] Example 1:

[0042] A sewage treatment project in Shandong, with a daily water treatment capacity of 30,000 tons, uses a pure membrane MBBR process for deep denitrification. The designed hydraulic retention time of the pure membrane MBBR anoxic zone is 0.4h, the carrier filling rate of the pure membrane MBBR anoxic zone is 55%, and the effective specific surface area of ​​the suspended carrier is 800m 2 / m 3 , stirring power density 15W / m 3The system is designed with an influent nitrate concentration of 25 mg / L, a COD of 100 mg / L, an effluent nitrate concentration of 10 mg / L, and a nitrification liquid reflux ratio of 150%. During the project startup phase, the influent flow rate was 3,000 tons / day. After 7 days of cultivation, the average effluent nitrate concentration dropped to 8.9 mg / L. Thereafter, the influent flow rate was gradually increased to 30,000 tons / day, and the effluent nitrate concentration was always controlled below 10 mg / L, with an average of 8.5 mg / L. On the 59th day of operation, the denitrification load in the anoxic zone of the pure membrane MBBR was measured to be 0.91 kgN / m 3 / d, the biofilm thickness was 230μm, and the relative abundance of biofilm denitrifying bacteria was 23.35%. Then it entered the acclimation stage, gradually increasing the reflux ratio of the nitrification solution to 300%, and the nitrous acid accumulation rate gradually increased to 87%. The nitrite load of the system was measured to be 0.83kgN / m 3 / d, the biofilm thickness reached 310μm, the relative abundance of biofilm denitrifying bacteria was 27.61%, and the acclimation was completed. After that, the reflow ratio was dynamically adjusted according to the actual influent water quality, and the system nitrous acid accumulation rate was always maintained above 85%, and the average nitrite load was 0.71kgN / m 3 / d, the average biofilm thickness was 335 μm, and the average relative abundance of biofilm denitrifying bacteria was 27.11%.

[0043] Example 2:

[0044] A wastewater treatment project in Shandong Province used both an activated sludge system and a pure membrane MBBR system to initiate a short-range denitrification pilot. The two systems had similar startup methods, using startup, acclimation, and stable operation control measures. Both systems had no water flow restrictions to verify maximum treatment capacity. Specific parameters for each stage are shown in Table 1:

[0045] Table 1

[0046]

[0047] As shown in Table 1, both the activated sludge process and the pure membrane MBBR method achieved short-cut denitrification, with comparable nitrous oxide accumulation rates. However, the pure membrane MBBR system achieved over double the load and relative abundance of functional bacteria compared to the activated sludge system, maintaining a stable HRT below 0.5 h, while the activated sludge system only reached a minimum of 1.1 h. In terms of engineering conversion, the pure membrane MBBR method for short-cut denitrification reduced land use by over 50%, achieved higher loads, and the higher relative abundance of functional bacteria also improved the system's ability to withstand shocks, resulting in more stable treatment results.

[0048] In summary, the present invention adopts a pure biofilm method to improve the short-range denitrification load of the system, and the hydraulic retention time of the anoxic zone is less than 0.5h, which can achieve a significant reduction in land occupation.

[0049] Parts not described in the present invention can be implemented by referring to the existing technology.

[0050] Those skilled in the art should recognize that the above embodiments are merely intended to illustrate the present application and are not intended to limit the present application. Any appropriate changes and modifications to the above embodiments should fall within the scope of protection of the claims of the present application as long as they are within the spirit of the present application.

Claims

1. A method for achieving short-range denitrification of suspended carrier biofilm, characterized in that: The system used includes a pure membrane MBBR anoxic zone and an aerobic zone, and the method includes the following steps in sequence: S1, startup phase Sewage is introduced into the anoxic zone of the pure membrane MBBR, and the flow of sewage is controlled to maintain the nitrate nitrogen concentration of the system effluent ≤10mg / L; at this time, the C / N ratio of the inlet water in the anoxic zone of the pure membrane MBBR is K0, 2≤K0≤4; the nitrification liquid reflux ratio of the aerobic zone is R0, and the denitrification load is>0.8kgN / m 3 / d, biofilm thickness>200μm, relative abundance of biofilm denitrifying bacteria>20%, pure membrane MBBR anoxic zone hydraulic retention time HRT<0.5h; S2, domestication stage Keep the sewage flow and water quality unchanged, and gradually increase the nitrification liquid return ratio R in the aerobic zone by 10% until the nitrous acid accumulation rate NAR in the anoxic zone of the pure membrane MBBR is greater than 80%, and the acclimation is completed; S3, stable stage Entering the stable operation stage, the C / N ratio of the influent in the anoxic zone of the pure membrane MBBR is K1, 1≤K1≤2, the nitrification liquid reflux ratio in the aerobic zone is R1, R1≤400%, and the nitrification load is >0.8kgN / m 3 / d, biofilm thickness>200μm, relative abundance of biofilm denitrifying bacteria>20%, pure membrane MBBR anoxic zone hydraulic retention time HRT<0.5h; The nitrification liquid reflux ratio is dynamically adjusted to maintain the C / N ratio of the influent in the anoxic zone of the pure membrane MBBR at 1-2, and the nitrification liquid reflux ratio is ≤400%, thus achieving a stable short-range denitrification process, with a nitrous accumulation rate NAR>80% and a nitrite load>0.6kgN / m 3 / d, biofilm thickness>200μm, relative abundance of biofilm denitrifying bacteria>20%, and hydraulic retention time HRT of the anoxic zone of pure membrane MBBR<0.5h.

2. The method for realizing short-range denitrification of suspended carrier biofilm according to claim 1, characterized in that: A suspended carrier is added into the anoxic zone of the pure membrane MBBR, and the filling rate of the suspended carrier is greater than 50%.

3. The method for realizing short-range denitrification of suspended carrier biofilm according to claim 2, characterized in that: The effective specific surface area of ​​the suspension carrier is ≥800m 2 / m 3 , specific gravity is 1.01~1.

05.

4. The method for realizing short-range denitrification of suspended carrier biofilm according to claim 1, characterized in that: The MLSS of the anoxic zone of the pure membrane MBBR is less than 200 mg / L.

5. The method for realizing short-range denitrification of suspended carrier biofilm according to claim 1, characterized in that: The pure membrane MBBR anoxic zone is equipped with a stirrer, and the stirring power density of the stirrer is greater than 7.5W / m 3 Pool content.

6. The method for achieving short-range denitrification using a suspended carrier biofilm according to claim 1, wherein: During the startup phase of S1, sewage is first introduced into the anoxic zone of the pure membrane MBBR, and the initial flow rate of the sewage is controlled to be 10% of the design flow rate until the nitrate nitrogen concentration in the system effluent is ≤10mg / L; When the nitrate-nitrogen concentration in the system effluent is ≤10mg / L, increase the sewage inlet flow rate to the design flow rate to keep the nitrate-nitrogen concentration in the system effluent ≤10mg / L.

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