Method for realizing short-range denitrification of suspended carrier biological membrane

Abstract

The invention discloses a method for realizing short-range denitrification of a suspended carrier biological membrane, and relates to the technical field of sewage. The method comprises the following steps: a starting stage: firstly introducing actual sewage into a pure membrane MBBR anoxic zone with an initial flow being 10% of a designed flow until the nitrate concentration of effluent is less than or equal to 10mg / L, then gradually increasing the water inlet flow to the designed flow and always ensuring that the nitrate concentration of the effluent is less than or equal to 10mg / L; then entering a domestication stage, keeping the water inlet flow and the water quality unchanged, and gradually increasing the nitrification liquid reflux ratio of the aerobic zone according to the proportion of 10% until the nitrous accumulation rate NARgt of the anoxic zone; 80%; and finally entering a stable stage. The short-range denitrification process based on a pure biological membrane method is realized, flora obligate culture is realized, short-range instability easily caused by circulation of an activated sludge multifunctional region is broken, operation control is 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 issues 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, but 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 is necessary to balance the relationship between the nitrous oxide accumulation rate and the nitrous oxide production rate.

[0003] At present, in order to achieve a stable short-term 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 the online pH meter and automatic control system to adjust the dosage of the agent, control the pH in the system to 8.0-9.5, and configure various carbon sources to ensure C / N, and achieve short-range denitrification effect through continuous pH control. It also has the following technical problems: First, the pH and automatic control system are used to form short-range denitrification, and the pH needs to be controlled at a high level. For the activated sludge system, the sludge circulates in different functional areas. High pH is not conducive to the activity of other bacteria such as nitrifying bacteria. At the same time, the fluctuation of pH value in other functional areas is also easy to cause the degradation of short-range denitrifying bacteria and destroy the short-range effect; secondly, the use of activated sludge method has a low load, which is bound to cause the anoxic zone to be too large, which is inconsistent 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 culturing short-range denitrifying bacteria and producing nitrous acid using fermented sludge as a carbon source, wherein the residual sludge is mixed and then enters a sludge fermentation coupled short-range denitrification reactor to complete sludge hydrolysis and acidification, and then the nitrification liquid enters the reactor to achieve the production of nitrous acid. In the sludge fermentation coupled short-range denitrification reactor, the sludge fermentation microorganisms first ferment the residual sludge into easily degradable organic matter, achieve sludge reduction and provide a carbon source for short-range denitrification; after the sludge fermentation is completed, the fermentation product is used as a carbon source to achieve short-range denitrification. The method also has the following technical problems: first, the premise for the method to produce a short-range denitrification effect is good sludge fermentation, which is relatively cumbersome to control. At the same time, most sewage treatment plants do not have the conditions for sludge fermentation, and the feasibility of engineering is low; second, the method is still based on the activated sludge method, and it is difficult to avoid the inherent problems of short-range instability, low load, and excessive land occupation caused by the training flow of the activated sludge method.

[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 too costly or complex to operate, which is not conducive to large-scale promotion and application.

[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 realizing 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 realizing short-range denitrification of suspended carrier biofilm, the system used includes pure membrane MBBR anoxic zone and aerobic zone, the method comprising the following steps in sequence:

[0011] S1. Startup phase

[0012] Sewage is introduced into the anoxic zone of the pure membrane MBBR to control the flow of sewage and keep the nitrate nitrogen concentration of the system effluent ≤10mg / L; at this time, the inlet C / N of 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. Acclimation 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 acid accumulation rate NAR in the anoxic zone of the pure membrane MBBR is > 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 nitrite 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 reflow ratio is dynamically adjusted to keep the C / N ratio of the pure membrane MBBR anoxic zone inlet water always 1-2, and the nitrification liquid reflow ratio is ≤400%, to achieve a stable short-range denitrification process, nitrous acid accumulation rate NAR>80%, nitrite load>0.6kgN / m 3 / d, biofilm thickness>200μm, relative abundance of biofilm denitrifying bacteria>20%, hydraulic retention time HRT of anoxic zone of pure membrane MBBR<0.5h.

[0018] In the above-mentioned method for realizing short-range denitrification of suspended carrier biofilm, 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%.

[0019] The above-mentioned 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-mentioned method for realizing short-range denitrification of suspended carrier biofilm, the pure membrane MBBR anoxic zone is equipped with a stirrer, and the stirring power density of the stirrer is>7.5W / m 3 Pool capacity.

[0022] In the above method for realizing short-range denitrification of suspended carrier biofilm, in the startup stage 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 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 flora, eliminates the short-range instability caused by the multifunctional zone circulation of activated sludge, 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 can be achieved under actual sewage conditions. The operation control is simple and does not interfere with the normal operating parameters of the project, thus ensuring the stability of the operation.

[0027] (3) The use of pure biofilm method increases 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 realizing short-range denitrification of suspended carrier biofilm. In order to make the advantages and technical solutions of the present invention clearer and more specific, the present invention is further described below in conjunction with specific embodiments.

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

[0030] S1. Startup phase

[0031] First, introduce sewage into the anoxic zone of the pure membrane MBBR, and control the initial flow rate of sewage to 10% of the design flow rate until the nitrate nitrogen concentration of the system effluent 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, maintain the nitrate-nitrogen concentration in the system effluent ≤10mg / L, and 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. Acclimation stage

[0035] Keep the flow rate and water quality of sewage unchanged, and gradually increase the nitrification liquid reflow 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 > 80%, and the acclimation is completed. Based on the reflow ratio, C / N is controlled without adding external chemicals or changing the inlet flow rate, which ensures 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 nitrite 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 reflow ratio is dynamically adjusted to keep the C / N ratio of the pure membrane MBBR anoxic zone inlet water always 1-2, and the nitrification liquid reflow ratio is <400%, to achieve a stable short-range denitrification process, nitrous acid accumulation rate NAR>80%, nitrite load>0.6kgN / m 3 / d, biofilm thickness>200μm, relative abundance of biofilm denitrifying bacteria>20%, hydraulic retention time HRT of 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 , specific gravity is 1.01~1.05, MLSS of pure membrane MBBR anoxic zone is less than 200mg / L, pure membrane MBBR anoxic zone is equipped with a stirrer, and the stirring power density of the stirrer is >7.5W / m 3 Pool capacity.

[0040] The present invention will be further described below in conjunction with specific embodiments.

[0041] Embodiment 1:

[0042] A sewage treatment project in Shandong, with a water treatment capacity of 30,000 tons / day, uses pure membrane MBBR technology for deep denitrification. The hydraulic retention time of the pure membrane MBBR anoxic zone is designed to be 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 3. The 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%. At the start-up phase of the project, the influent volume was 3,000 tons / day. After 7 days of cultivation, the average effluent nitrate concentration dropped to 8.9 mg / L. After that, the influent flow rate was gradually increased to 30,000 tons / day. 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 reach 0.91 kgN / m 3 / d, biofilm thickness 230μm, relative abundance of biofilm denitrifying bacteria 23.35%. Then enter the acclimation stage, gradually increase the reflux ratio of nitrification liquid to 300%, 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 domestication was completed. After that, the reflow ratio was dynamically adjusted according to the actual influent water quality, 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] Embodiment 2:

[0044] A sewage treatment project in Shandong Province used both an activated sludge system and a pure membrane MBBR system to start a short-range denitrification pilot. The startup methods of the two systems were similar, and both adopted the control methods of startup, acclimatization and stable operation. Both systems did not limit the water volume to verify the maximum treatment capacity. The specific parameters of each stage are shown in Table 1:

[0045] Table 1

[0046]

[0047] As shown in Table 1, both the activated sludge method and the pure membrane MBBR method achieved short-range denitrification effects, and the nitrous acid accumulation rate was comparable, but the load and relative abundance of functional bacteria in the pure membrane MBBR system were more than double those of the activated sludge system, and the HRT could be stabilized below 0.5h, while the activated sludge system could only be reduced to 1.1h at its lowest. Corresponding to the engineering transformation, the use of pure membrane MBBR to achieve short-range denitrification can reduce the land occupation by more than 50%, with a higher load, and a higher relative abundance of functional bacteria, which also improves the system's ability to withstand shocks, and the treatment effect is more stable.

[0048] In summary, the present invention adopts a pure biofilm method to increase 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 only used to illustrate the present application and are not intended to be limiting of the present application. As long as they are within the spirit of the present application, appropriate changes and modifications to the above embodiments should fall within the scope of protection of the claims of the present application.

Claims

1. A method for realizing 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 to control the flow of sewage and keep the nitrate nitrogen concentration of the system effluent ≤10mg / L; at this time, the inlet C / N of 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. Acclimation 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 > 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 nitrite 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 reflow ratio is dynamically adjusted to keep the C / N ratio of the pure membrane MBBR anoxic zone inlet water always 1-2, and the nitrification liquid reflow ratio is ≤400%, to achieve a stable short-range denitrification process, nitrous acid accumulation rate NAR>80%, nitrite load>0.6kgN / m 3 / d, biofilm thickness>200μm, relative abundance of biofilm denitrifying bacteria>20%, hydraulic retention time HRT of anoxic zone of pure membrane MBBR<0.5h.

2. A 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. A 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. A 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>7.5W / m 3 Pool capacity.

6. A method for realizing short-range denitrification of suspended carrier biofilm according to claim 1, characterized in that: In the startup phase of S1, sewage is first introduced into the anoxic zone of the pure membrane MBBR, and the initial flow rate of sewage is controlled to be 10% of the design flow rate until the nitrate nitrogen concentration of 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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