Method and device for deducing sludge age based on flow to control excess sludge discharge

Abstract

The invention provides a method and device for controlling excess sludge discharge by deducing sludge age based on flow, and belongs to the technical field of sewage treatment. The method comprises the following steps: obtaining the effective volume of a biochemical tank, wherein the biochemical tank comprises an anaerobic tank, an anoxic tank, an aerobic tank and a secondary sedimentation tank which are communicated in sequence; a water inlet pipeline, a sludge return pipeline, a residual sludge discharge pipeline and a water outlet pipeline; acquiring flow data of a water inlet pipeline, a sludge return pipeline and a residual sludge discharge pipeline; acquiring flow data of the mixed liquid entering the secondary sedimentation tank according to water balance; obtaining the sludge concentration in the sludge return pipeline according to the mass conservation; and according to the obtained effective volume of the biochemical pool and the flow data of the pipeline, controlling the residual sludge discharge by adopting a sludge age calculation formula. Sludge age SRT can be timely and accurately deduced only according to related flow and known parameters, and residual sludge discharge is controlled by an SRT method, so that stable operation and treatment effect of a sewage biochemical treatment system are ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage treatment, and particularly relates to a method and device for controlling the discharge of excess sludge based on flow derivation of sludge age. Background Technique

[0002] The statements in this part only provide background technical information related to the present invention and do not necessarily constitute prior art.

[0003] The activated sludge biochemical method is the most widely used method in sewage treatment. During the treatment process, the microorganisms in the activated sludge continuously consume the organic matter in the sewage. Part of the organic matter is oxidized to provide the energy required for the life activities of the microorganisms, and the other part of the organic matter is utilized by the microorganisms to synthesize new cytoplasm, thereby enabling the microorganisms to multiply and proliferate. Therefore, excess sludge is generated and needs to be discharged from the system to maintain the stable operation of the system.

[0004] The main methods for controlling the discharge of excess sludge include the 30-minute sedimentation ratio (SV30) method, the mixed liquor suspended solids (MLSS) method, the sludge retention time (SRT) method, the sludge loading (F / M) method, etc. Among them, the SV30 method is to control the SV30 of the biochemical system to remain constant. Due to the frequent change of the sludge volume index (SVI), the SV30 method is unreliable, and the SV30 method cannot adapt to the changes in the influent water quality and quantity, making it only suitable for the control of excess sludge discharge in short-term and stable biochemical treatment systems; the MLSS method is to control the MLSS of the biochemical system to remain constant. The MLSS method, like the SV30 method, cannot adapt to the changes in the influent water quality and quantity, making it only suitable for the control of excess sludge discharge in short-term and stable biochemical treatment systems; the F / M method is to control the F / M of the biochemical system to remain constant. Although it can adapt to the changes in the influent water quality and quantity, it is necessary to simultaneously measure the influent biochemical oxygen demand (BOD5) or chemical oxygen demand (CODcr) and the MLSS of the biochemical system, and calculate the F / M, which is very cumbersome. Moreover, when the influent water quality and quantity change, the F / M will also change accordingly, bringing difficulties to the control of excess sludge discharge, and it is difficult to apply in general small and medium-sized sewage treatment plants and stations; the SRT method is to control the SRT of the biochemical system to remain constant, which can adapt to the changes in the influent water quality and quantity, and the system operates stably and reliably, and is considered to be the best method for controlling the discharge of excess sludge.

[0005] Although the SRT method has obvious advantages, many small and medium-sized sewage treatment plants and stations do not have the conditions to measure and calculate the SRT in a timely and accurate manner, resulting in the failure of this method to be widely applied. Many small and medium-sized sewage treatment plants and stations have abnormal problems such as sludge aging, sludge bulking, and poor treatment effects due to improper control of excess sludge discharge, affecting the stable operation and treatment effect of the sewage biochemical treatment system. Summary of the Invention

[0006] To overcome the deficiencies of the above-mentioned prior art, the present invention provides a method and device for controlling the discharge of excess sludge based on flow rate to derive sludge age. By setting multiple flow meters and establishing a corresponding calculation method for sludge age SRT, the sludge age SRT can be derived promptly and accurately only based on relevant flow rates and known parameters, and the discharge of excess sludge is controlled by the SRT method, thereby ensuring the stable operation and treatment effect of the sewage biochemical treatment system.

[0007] To achieve the above object, one or more embodiments of the present invention provide the following technical solutions:

[0008] The first aspect of the present invention provides a method for controlling the discharge of excess sludge based on flow rate to derive sludge age, including;

[0009] Obtain the effective volume of the biochemical pool, which includes an anaerobic pool, an anoxic pool, an aerobic pool, and a secondary sedimentation tank connected in sequence; as well as an influent pipeline, a sludge return pipeline, an excess sludge discharge pipeline, and an effluent pipeline;

[0010] Respectively obtain the flow rate data of the influent pipeline, the sludge return pipeline, and the excess sludge discharge pipeline;

[0011] Obtain the flow rate data of the mixed liquor entering the secondary sedimentation tank according to the water balance; based on the obtained flow rate data of the mixed liquor entering the secondary sedimentation tank, obtain the sludge concentration in the sludge return pipeline according to the mass conservation;

[0012] Calculate the sludge age according to the obtained effective volume of the biochemical pool, the flow rate data of the pipelines, and the sludge concentration, and then control the discharge of excess sludge.

[0013] As a further technical solution, the outlet of the aerobic pool is connected to the inlet of the anoxic pool through an internal return pipeline;

[0014] The outlet of the secondary sedimentation tank is connected to the anaerobic pool through a sludge return pipeline; the sludge return pipeline is also connected to the excess sludge pipeline.

[0015] As a further technical solution, an influent flow meter, a sludge return flow meter, and an excess sludge discharge flow meter are respectively arranged on the influent pipeline, the sludge return pipeline, and the excess sludge discharge pipeline for obtaining the flow rate data of the pipelines.

[0016] As a further technical solution, the sludge concentrations in the anaerobic pool, the anoxic pool, the aerobic pool, the internal return pipeline, and the secondary sedimentation tank are equal; the sludge concentrations in the sludge return pipeline and the excess sludge pipeline are equal.

[0017] As a further technical solution, the water balance means that the flow rate data source of the mixed liquor entering the secondary sedimentation tank is equal to the flow rate data of the mixed liquor leaving the secondary sedimentation tank.

[0018] As a further technical solution, the flow rate data of the secondary sedimentation tank mixed liquor is the sum of the flow rate data of the sludge return pipeline, the flow rate data of the excess sludge discharge pipeline, and the flow rate data of the outlet pipeline.

[0019] As a further technical solution, the mass conservation means that the mass of the sludge entering the secondary sedimentation tank is equal to the mass of the sludge leaving the secondary sedimentation tank.

[0020] As a further technical solution, the sludge age calculation formula is as follows:

[0021]

[0022] In the formula, SRT is the sludge age; Q is the flow rate data of the inlet pipeline; q1 is the flow rate data of the sludge return pipeline; q2 is the flow rate data of the excess sludge return pipeline; V is the effective volume of the biochemical tank.

[0023] The second aspect of the present invention provides a device for controlling excess sludge discharge based on the sludge age derived from the flow rate, including:

[0024] An anaerobic tank, an anoxic tank, an aerobic tank, and a secondary sedimentation tank connected in sequence through pipelines; the anaerobic tank is connected to the inlet pipeline, and an inlet flow meter is arranged on the inlet pipeline; the secondary sedimentation tank is connected to the outlet pipeline;

[0025] The outlet of the aerobic tank is also connected to the inlet of the anoxic tank through an internal reflux pipeline;

[0026] The outlet of the secondary sedimentation tank is also connected to the anaerobic tank through a sludge return pipeline; the sludge return pipeline is also connected to the excess sludge pipeline; a sludge return flow meter is arranged on the sludge return pipeline; an excess sludge discharge flow meter is arranged on the excess sludge pipeline.

[0027] As a further technical solution, the inlet flow meter, the sludge return flow meter, and the excess sludge discharge flow meter all adopt electromagnetic flow meters.

[0028] The above one or more technical solutions have the following beneficial effects:

[0029] (1) The present invention only needs to set 3 sets of flow meters for inlet water, sludge return, and excess sludge discharge in the inlet pipeline, the sludge return pipeline, and the excess sludge discharge pipeline, without other technical transformations. Its structure is simple and the cost is low. It is applicable to various biochemical treatment processes such as the traditional activated sludge method, the anoxic-aerobic biological nitrogen removal process, the anaerobic-aerobic biological phosphorus removal process, and the anaerobic-anoxic-aerobic biological nitrogen and phosphorus removal process, that is, it is suitable for both new projects and old projects.

[0030] (2) The method and device for controlling the discharge of surplus sludge based on flow rate derivation of sludge age provided by the present invention can instantaneously and accurately derive the sludge age only based on variables such as the hourly influent flow rate Q, the hourly sludge return flow rate q1, and the hourly surplus sludge discharge flow rate q2, and control the discharge of surplus sludge by the SRT method, enabling the majority of small and medium-sized sewage treatment plants and stations to control the discharge of surplus sludge by the SRT method, effectively preventing a series of problems such as sludge aging, sludge bulking, and poor treatment effect caused by improper control of the discharge of surplus sludge in the sewage biochemical treatment system, and providing a guarantee for the stable operation of the sewage biochemical treatment system.

[0031] Advantages of additional aspects of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings forming a part of this specification are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0033] Figure 1 It is a flowchart of the method for the first embodiment.

[0034] Figure 2 It is a schematic structural diagram of the device for the second embodiment.

[0035] In the figure, 1 is an anaerobic tank; 2 is an anoxic tank; 3 is an aerobic tank; 4 is a secondary sedimentation tank; 5 is an internal reflux pipeline; 6 is a sludge return pipeline; 7 is a surplus sludge discharge pipeline; 8 is an influent pipeline; 9 is an effluent pipeline; 10 is an influent flowmeter; 11 is a sludge return flowmeter; 12 is a surplus sludge discharge flowmeter DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0037] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention.

[0038] Without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0039] Embodiment 1

[0040] This embodiment discloses a method for controlling the discharge of surplus sludge based on flow rate derivation of sludge age;

[0041] As Figure 1As shown in the figure, a method for controlling the discharge of excess sludge based on flow rate to deduce sludge age includes:

[0042] Step S1, obtaining the effective volume V of the biochemical tank. The biochemical tank includes an anaerobic tank 1, an anoxic tank 2, an aerobic tank 3, and a secondary sedimentation tank 4 that are connected in sequence; as well as an influent pipeline 8, a sludge return pipeline 6, an excess sludge discharge pipeline 7, and an effluent pipeline 9;

[0043] The effective volume of the biochemical tank in the biochemical treatment system is determined and known, and can be obtained by querying relevant design materials. In this embodiment, the biochemical tank includes an anaerobic tank 1, an anoxic tank 2, an aerobic tank 3, and a secondary sedimentation tank 4 that are connected in sequence; the outlet of the aerobic tank 3 is connected to the inlet of the anoxic tank 2 through an internal return pipeline 5; the outlet of the secondary sedimentation tank 4 is connected to the anaerobic tank 1 through a sludge return pipeline 6; the sludge return pipeline 6 is also connected to the excess sludge discharge pipeline 7. Based on this, the sludge concentration in the biochemical tank is defined as M. Since the internal return pipeline 5 in this embodiment is directly connected to the anaerobic tank 1, anoxic tank 2, aerobic tank 3, and secondary sedimentation tank 4 in the biochemical tank, the sludge concentration in the anaerobic tank 1, anoxic tank 2, aerobic tank 3, secondary sedimentation tank 4, and internal return pipeline 5 is also M. Since the influent sludge concentration is usually not considered when calculating the sludge age, the sludge concentration of the influent pipeline 8 is recorded as 0.

[0044] Step S2, respectively obtaining the flow rate data of the influent pipeline 8, the flow rate data of the sludge return pipeline 6, and the flow rate data of the excess sludge discharge pipeline 7;

[0045] In step S2, the flow rate data of the influent pipeline 8, the flow rate data of the sludge return pipeline 6, and the flow rate data of the excess sludge discharge pipeline 7 are obtained through electromagnetic flowmeters. The electromagnetic flowmeters include an influent flowmeter 10, a sludge return flowmeter 11, and an excess sludge discharge flowmeter 12, which are respectively arranged on the influent pipeline 8, the sludge return pipeline 6, and the excess sludge discharge pipeline 7.

[0046] The flow rate data of the influent flowmeter 10 is recorded as Q; the flow rate data of the sludge return flowmeter 11 is recorded as q1, and the sludge concentration is recorded as m1; the hourly flow rate of the excess sludge discharge flowmeter 12 is recorded as q2. Since the excess sludge discharge pipeline 7 is directly connected to the sludge return pipeline 6, the sludge concentration in the excess sludge discharge pipeline 7 is the same as that in the sludge return pipeline 6, which is also m1.

[0047] Step S3, obtaining the flow rate data of the mixed liquid entering the secondary sedimentation tank 4 according to the water volume balance; based on the obtained flow rate data of the mixed liquid entering the secondary sedimentation tank 4, obtaining the sludge concentration in the sludge return pipeline 6 according to the mass conservation;

[0048] First, according to the water balance, the flow rate data of the outlet pipeline 9 can also be determined. The flow rate data of the outlet pipeline 9 is the difference between the flow rate data Q of the inlet pipeline 8 and the flow rate data q2 of the surplus sludge discharge pipeline 7, that is, the flow rate data of the outlet pipeline 9 is Q - q2.

[0049] In the process of obtaining the hourly flow rate of the mixed liquor entering the secondary sedimentation tank 4 according to the water balance, the water balance means that the flow rate data of the mixed liquor entering the secondary sedimentation tank 4 is equal to the flow rate data of the mixed liquor leaving the secondary sedimentation tank 4. Therefore, the flow rate data of the mixed liquor in the secondary sedimentation tank 4 is the sum of the flow rate data q1 of the sludge return pipeline 6, the flow rate data q2 of the surplus sludge discharge pipeline 7, and the flow rate data Q - q2 of the outlet pipeline 9, that is, the flow rate data of the mixed liquor in the secondary sedimentation tank 4 is Q + q1.

[0050] Since the sludge concentration entering the secondary sedimentation tank 4 is also M, according to the law of conservation of mass, the sludge mass entering the secondary sedimentation tank 4 is equal to the sludge mass leaving the secondary sedimentation tank 4, that is:

[0051] M×(Q + q1) = m1×(q1 + q2)

[0052] Based on the above formula, the sludge concentration in the sludge return pipeline 6 is:

[0053]

[0054] Obtain the sludge concentration in the sludge return pipeline 6 according to the law of conservation of mass;

[0055] Step S4, calculate the sludge age based on the obtained effective volume of the biochemical tank, the flow rate data of the pipeline, and the sludge concentration, and then control the discharge of surplus sludge;

[0056] In the control of the discharge of surplus sludge based on the sludge age method, the sludge concentration in the secondary sedimentation tank 4, the sludge concentration in the internal return pipeline 5, and the sludge concentration in the sludge return pipeline 6 are usually ignored when calculating the sludge age. Therefore, the calculation formula for the sludge age is:

[0057]

[0058] Combined with the above formula, it can be seen that V is a known constant. To obtain the sludge age value, it is necessary to measure M, m1, and q2. Since the measurement of M and m1 is relatively cumbersome, and m1 will change with the changes of M, Q, q1, and q2, there will be a large error in estimating with historical data, and it needs to be measured frequently.

[0059] Based on this, substituting the sludge concentration formula in the sludge return pipeline 6 measured in step S3 into the calculation formula for the sludge age, the calculation formula for the sludge age can be expressed as:

[0060]

[0061] Combined with the above formula, only the flow rate data Q of the influent pipeline 8, the flow rate data q1 of the sludge return pipeline 6, and the flow rate data q2 of the excess sludge discharge pipeline 7 need to be measured, without relying on the determination of sludge concentration. Then, the SRT can be accurately derived immediately, which is very convenient and provides a reliable basis for the sewage treatment plant to control the excess sludge discharge by the SRT method. In addition, it can be seen from the above formula that the derivation process and result of the SRT are not affected by the flow rate of the internal return pipeline 5. That is, whether it is the traditional activated sludge method, the anoxic-aerobic biological nitrogen removal process, the anaerobic-aerobic biological phosphorus removal process, or the anaerobic-anoxic-aerobic biological nitrogen and phosphorus removal process, the SRT can be derived according to the technical method provided by the present invention.

[0062] Embodiment 2

[0063] This embodiment discloses a device for controlling the excess sludge discharge based on the derivation of sludge age from flow rate;

[0064] As Figure 2 shown, the device for controlling the excess sludge discharge based on the derivation of sludge age from flow rate includes:

[0065] An anaerobic tank 1, an anoxic tank 2, an aerobic tank 3, and a secondary sedimentation tank 4 that are connected in sequence through pipelines; the anaerobic tank 1 is connected to the influent pipeline 8, and an influent flowmeter 10 is provided on the influent pipeline 8; the secondary sedimentation tank 4 is connected to the effluent pipeline 9;

[0066] The outlet of the aerobic tank 3 is also connected to the inlet of the anoxic tank 3 through an internal return pipeline 5. The internal return pipeline 5 can promote the contact frequency between microorganisms and organic matter, thereby promoting the degradation of chemical oxygen demand (COD). Under anoxic or anaerobic conditions, internal return can also enhance the denitrification effect, further removing nitrates and organic pollutants in the sewage and indirectly reducing COD.

[0067] The outlet of the secondary sedimentation tank 4 is also connected to the anaerobic tank 1 through a sludge return pipeline 6; part of the activated sludge is returned from the secondary sedimentation tank 4 to the anaerobic tank 1 through the sludge return pipeline 6 to ensure sufficient microbial quantity. In addition, the sludge return pipeline 6 also helps to form a more uniform mixed liquid, promoting more sufficient contact and reaction between microorganisms and pollutants in the sewage. This increase in contact opportunities can significantly improve the pollutant removal efficiency.

[0068] The sludge return pipeline 6 is also connected to the excess sludge discharge pipeline 7, and a sludge return flowmeter 11 is provided on the sludge return pipeline 6; an excess sludge discharge flowmeter 12 is provided on the excess sludge discharge pipeline 7.

[0069] Among them, the influent flowmeter 10, the sludge return flowmeter 11, and the excess sludge discharge flowmeter 12 all adopt electromagnetic flowmeters, which can achieve precise detection of the internal flow rate of the pipeline.

[0070] In this embodiment, since the anaerobic tank 1, the anoxic tank 2, the aerobic tank 3, the internal reflux pipeline 5 and the secondary sedimentation tank 4 are connected, the sludge concentration inside the above structure is consistent; after the sedimentation and separation in the secondary sedimentation tank 4, the sludge concentrations in the flowing sludge return pipeline 6 and the excess sludge pipeline 7 are equal.

[0071] Although the specific implementation manners of the present invention are described above in conjunction with the accompanying drawings, they do not limit the protection scope of the present invention. Those skilled in the art should understand that, based on the technical solution of the present invention, various modifications or deformations that can be made by those skilled in the art without creative efforts are still within the protection scope of the present invention.

Claims

1. A method for controlling excess sludge discharge based on flow rate-based sludge age derivation, characterized in that: include; Obtaining the effective volume of the biochemical pool, wherein the biochemical pool includes an anaerobic pool, an anoxic pool, an aerobic pool and a secondary sedimentation tank connected in sequence; as well as an inlet pipeline, a sludge return pipeline, a residual sludge discharge pipeline and an outlet pipeline; Respectively obtain the flow data of the water inlet pipeline, the flow data of the sludge return pipeline, and the flow data of the excess sludge discharge pipeline; The flow data of the mixed liquor entering the secondary sedimentation tank is obtained according to the water balance; based on the obtained flow data of the mixed liquor entering the secondary sedimentation tank, the sludge concentration in the sludge return pipeline is obtained according to the law of mass conservation; Based on the acquired effective volume of the biochemical pool and the flow rate data of the pipeline, the sludge age calculation formula is used to control the discharge of residual sludge.

2. The method for controlling excess sludge discharge by deriving sludge age based on flow rate as claimed in claim 1, characterized in that: The outlet of the aerobic tank is connected to the inlet of the anoxic tank through an internal reflux pipeline; The outlet of the secondary sedimentation tank is connected to the anaerobic tank through a sludge return pipeline; the sludge return pipeline is also connected to the residual sludge pipeline.

3. The method for controlling excess sludge discharge by deriving sludge age based on flow rate as claimed in claim 1, characterized in that: The water inlet pipeline, sludge return pipeline and excess sludge discharge pipeline are respectively provided with a water inlet flow meter, a sludge return flow meter and an excess sludge discharge flow meter for obtaining flow data of the pipelines.

4. The method for controlling excess sludge discharge based on flow rate derivation of sludge age as claimed in claim 1, characterized in that: The sludge concentrations in the anaerobic tank, the anoxic tank, the aerobic tank, the internal return pipeline and the secondary sedimentation tank are equal; the sludge concentrations in the sludge return pipeline and the residual sludge pipeline are equal.

5. The method for controlling excess sludge discharge by deriving sludge age based on flow rate as claimed in claim 1, characterized in that: The water balance is that the mixed liquor flow data source entering the secondary sedimentation tank is equal to the mixed liquor flow data leaving the secondary sedimentation tank.

6. The method for controlling excess sludge discharge based on flow rate derivation of sludge age as claimed in claim 1, characterized in that: The mixed liquor flow data of the secondary sedimentation tank is the sum of the flow data of the sludge return pipeline, the flow data of the excess sludge discharge pipeline and the flow data of the effluent pipeline.

7. The method for controlling excess sludge discharge based on flow rate derivation of sludge age as claimed in claim 1, characterized in that: The mass conservation law means that the mass of sludge entering and leaving the secondary sedimentation tank is equal.

8. The method for controlling excess sludge discharge based on flow rate derivation of sludge age as claimed in claim 1, characterized in that: The sludge age calculation formula is: In the formula, SRT is the sludge age; Q is the flow data of the water inlet pipeline; q1 is the flow data of the sludge return pipeline; q2 is the flow data of the residual sludge return pipeline; V is the effective volume of the biochemical pool.

9. A device for controlling the discharge of excess sludge based on flow rate-derived sludge age, characterized in that: include: An anaerobic tank, an anoxic tank, an aerobic tank and a secondary sedimentation tank are sequentially connected through pipelines; the anaerobic tank is connected to a water inlet pipe, and a water inlet flow meter is provided on the water inlet pipe; the secondary sedimentation tank is connected to a water outlet pipe; The outlet of the aerobic tank is also connected to the inlet of the anoxic tank through an internal reflux pipeline; The outlet of the secondary sedimentation tank is also connected to the anaerobic tank through a sludge return pipeline; the sludge return pipeline is also connected to a residual sludge pipeline; a sludge return flowmeter is provided on the sludge return pipeline; and a residual sludge discharge flowmeter is provided on the residual sludge pipeline.

10. The device for controlling excess sludge discharge based on flow rate derivation of sludge age as claimed in claim 9, characterized in that: The water inlet flowmeter, sludge return flowmeter and residual sludge discharge flowmeter all adopt electromagnetic flowmeters.

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