A magnetically loaded rapid culture system and method for activated sludge

Abstract

The application discloses a magnetic loading activated sludge rapid culture system and method, wherein the system comprises a biochemical tank, one end of the biochemical tank is connected with a sewage treatment system through a water inlet, the other end of the biochemical tank is connected with a sedimentation tank through a water outlet, a sludge backflow pump is connected with a material outlet at the bottom of the sedimentation tank, an outlet of the sludge backflow pump is connected with a water jet device, the water jet device is connected with a backflow inlet at the end of the biochemical tank, and a magnetic powder adding device is connected with an inlet at the bottom of the water jet device; the magnetic loading activated sludge rapid culture method of the application experiences sludge inoculation, magnetic sludge activation, magnetic powder adding, sludge training and stable operation stages, the whole culture period is controlled within 20-35 days, the magnetic loading activated sludge process initial debugging and operation time is shortened, and the discharge of residual sludge and unqualified wastewater is reduced.

Description

Technical Field

[0001] This invention belongs to the field of wastewater biological treatment technology, specifically relating to a magnetically loaded activated sludge rapid cultivation system and method. Background Technology

[0002] The activated sludge process is one of the most common wastewater treatment technologies, especially in large and medium-sized wastewater treatment plants. 2 Activated sludge treatment technologies include oxidation ditches and other methods. However, conventional activated sludge processes suffer from drawbacks such as large land area required for civil engineering structures, weak system resistance to shock loads, large excess sludge production, and sludge leakage in the secondary sedimentation tank. To address these shortcomings, adding packing material to the biological treatment tank to increase sludge concentration and shock resistance is a major direction for improving the activated sludge process. Magnetic loading activated sludge is an improved technology developed based on this. It involves adding magnetic powder to the activated sludge, causing the activated sludge flocs to adsorb and bind to the magnetic powder surface. Under the influence of a magnetic field, these flocs form more compact flocs, significantly improving sludge settling performance and achieving better sludge-water separation. This greatly reduces the volume of the bioreactor and sedimentation tank, increasing the treatment load and nitrogen and phosphorus removal efficiency.

[0003] In existing technologies, magnetic powder is typically added directly to a biological treatment tank for cultivation and acclimatization to obtain high-concentration magnetically loaded activated sludge. However, in actual cultivation processes, problems such as long cultivation time for magnetically loaded activated sludge, poor initial binding between sludge and magnetic powder, and significant loss of magnetic powder during addition exist.

[0004] Therefore, there is a need to propose a more economical, efficient, and easy-to-operate method for rapid cultivation of magnetically loaded activated sludge, in order to shorten the sludge cultivation and acclimatization cycle, increase the sludge concentration, and thus achieve good treatment results. Summary of the Invention

[0005] In view of the problems existing in the prior art, the purpose of this invention is to provide a rapid cultivation system and method for magnetically loaded activated sludge, which is used for sludge cultivation and acclimatization in the initial stage of commissioning of a magnetically loaded activated sludge system.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] This invention proposes a magnetically loaded activated sludge rapid cultivation system, characterized by comprising a biological treatment tank, wherein one end of the biological treatment tank is connected to a wastewater treatment system via a pipeline, and the other end of the biological treatment tank is connected to a sedimentation tank via a pipeline. The material outlet at the bottom of the sedimentation tank is connected to a sludge return pump via a pipeline, and the outlet of the sludge return pump is connected to a water ejector via a pipeline. The water ejector is connected to the return inlet at the end of the biological treatment tank via a pipeline, and a magnetic powder dosing device is connected to the bottom inlet of the water ejector.

[0008] Furthermore, it includes a magnetic powder pretreatment device, which is connected to the magnetic powder feeding device via a pipeline.

[0009] Furthermore, it includes a waste sludge pump and a magnetic separator. The waste sludge pump is connected to the material outlet at the bottom of the sedimentation tank via a pipeline. The side inlet of the magnetic separator is connected to the waste sludge pump via a pipeline. The bottom outlet of the magnetic separator is connected to the magnetic powder dosing device via a pipeline.

[0010] Furthermore, the biological treatment tank is equipped with an aeration and stirring system, which includes an aeration blower, a microporous aerator, and a flow-propelling agitator. The flow-propelling agitator is located at the top of the biological treatment tank, and the microporous aerator is installed at the bottom of the biological treatment tank. The microporous aerator works in conjunction with the aeration blower to deliver oxygen into the biological treatment tank to meet the dissolved oxygen requirements of each stage of sludge cultivation.

[0011] This invention also proposes a method for rapid cultivation of magnetically loaded activated sludge, wherein the method employs a magnetically loaded rapid activated sludge cultivation system, and the method includes the following steps:

[0012] 1) Sludge inoculation: Inject the wastewater to be treated into the biological treatment tank, add activated sludge, then add nutrients, and at the same time turn on the aeration and stirring system to perform sludge aeration. Control the dissolved oxygen in the biological treatment tank to 1-2 mg / L. When the sludge concentration gradually increases to 1000-3000 mg / L, maintain it for 1-3 days, and then start the sludge return pump to return the sludge.

[0013] 2) Magnetic mud activation: Add inoculation activated sludge and hydroxyl-activated magnetic powder to the magnetic powder feeding device, and mix them thoroughly and evenly using a stirrer;

[0014] 3) During the continuous aeration of the biological treatment tank, the activated magnetic sludge is added through the magnetic powder addition device. The water jet injector uniformly adds the evenly mixed return sludge and the activated magnetic sludge to the return inlet of the biological treatment tank and stirs it with the pusher mixer. During the magnetic powder addition, continuous aeration and the addition of nutrients are carried out for cultivation. The dissolved oxygen in the biological treatment tank is controlled at 1.5-2.5 mg / L. SV30 and MLSS are tested regularly, and the concentration of activated sludge is continuously increased to 3000-4500 mg / L.

[0015] 4) For sludge conditioning, continuously feed the wastewater to be treated into the biological treatment tank at 20% to 30% of the design flow rate, continuously stir and aerate, control the dissolved oxygen concentration at 2 to 3 mg / L, supplement the nutrients required for the activated sludge process, and regularly test the sludge concentration and effluent quality. After the test results meet the standards, gradually increase the amount of wastewater added to 50% of the volume of the biological treatment tank, and continue conditioning as described above until the sludge concentration and effluent quality meet the standards.

[0016] 5) Increase the sludge volume and return the sludge from the sedimentation tank to the design value. At the same time, increase the wastewater inflow to 70% of the design volume. Add the activated magnetic sludge mixture to the biological treatment tank again. Increase the aeration to 2.5-4 mg / L. Control the sludge discharge. Ensure that the SS index of the sedimentation tank effluent is less than 20 mg / L. Gradually increase the concentration of magnetically loaded activated sludge to 4500-8000 mg / L for 5-10 days.

[0017] 6) After step 5) is completed, the wastewater inflow is gradually increased to more than 100% of the design flow rate. The concentration of activated sludge in the biological treatment tank is stabilized at 6000~9000 mg / L, the dissolved oxygen is controlled at 2~3 mg / L, the activated sludge in the biological treatment tank has good properties, the SV30 is 40~50%, the effluent from the sedimentation tank is clear, and the effluent quality meets the design requirements. That is, the magnetic loading activated sludge cultivation is completed.

[0018] Further, in step 1), the activated sludge is a sludge cake with 80% moisture content, and the amount of activated sludge added accounts for 10-20% of the volume of the biological treatment tank; in step 2), the magnetic powder is a micron-sized magnetic powder with Fe3O4 content of not less than 95%, and the particle size distribution is 80-150 mesh with a proportion of not less than 90%. The magnetic powder is activated by hydroxylation treatment of its surface with hydrogen peroxide or sodium hydroxide, and the magnetic powder concentration is 150-170 mg / g dry sludge.

[0019] Further, in step 1), start the sludge return pump at a return ratio of 20%–30% to return the sludge; based on the microscopic examination of the magnetic sludge binding, control the amount of magnetic powder added to prevent excessive addition that could cause the magnetic powder to settle to the bottom. Add 1–2 batches of activated magnetic sludge daily for 5–7 days, continuously increasing the activated sludge concentration to 3000–4500 mg / L.

[0020] Further, in step 4), supplement the nutrients required for the activated sludge process according to the ratio of BOD5:N:P=100:5:1, and regularly test the sludge concentration and effluent quality; control the influent temperature at 12-38℃ and the pH value at 6.5-8.5, and while ensuring the biochemical effect, gradually increase the amount of wastewater added to 50% of the volume of the biological treatment tank; during the acclimation period, add a batch of activated magnetic sludge every 1-2 days and maintain for 5-10 days.

[0021] Furthermore, in step 6), the sludge concentration is 7000–8000 mg / L, and the magnetic powder concentration is 150–170 mg / g of dry sludge.

[0022] Furthermore, during the sludge inoculation, magnetic sludge addition, and sludge acclimatization stages, no sludge is discharged; aeration and plug mixing are continuously performed. During the sludge expansion stage, a small amount of sludge is discharged through the waste sludge pump to continuously increase the concentration of magnetically loaded activated sludge. During the stable operation stage, sludge is discharged normally through the waste sludge pump while ensuring effluent quality and activated sludge concentration. The activated sludge includes AO and A. 2 O, oxidation ditch or SBR.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1) The magnetic loading activated sludge rapid cultivation method of the present invention goes through various stages such as sludge inoculation, magnetic sludge activation, magnetic powder addition, sludge conditioning and stable operation. The entire cultivation cycle is controlled within 20 to 35 days, which shortens the initial commissioning and operation time of the magnetic loading activated sludge process and reduces the discharge of excess sludge and unqualified wastewater.

[0025] 2) The system of the present invention uses a water jet device installed at the outlet of the sludge return pump to mix the activated magnetic mud with the returned sludge using the Bernoulli effect, and adds it at a uniform rate to the return inlet of the biological treatment tank to cultivate the sludge. This avoids the problems of poor initial binding between sludge and magnetic powder, serious loss of magnetic powder during the addition process, and long cultivation time.

[0026] 3) This invention is applicable to the cultivation of magnetically loaded activated sludge in various magnetic biochemical wastewater treatment systems. The magnetic sludge is organically combined through magnetic powder activation, and the magnetic sludge is uniformly added through the jet nozzle of the sludge return pipe. High-concentration activated sludge is formed by loading biofilm and stable flocs on the surface of magnetic powder, thereby achieving better biochemical treatment effect.

[0027] 4) This invention adopts low-load continuous cultivation combined with continuous and uniform addition of magnetic mud. While increasing the concentration of activated sludge and magnetic powder in the biological treatment tank, it also increases the amount of sewage added for simultaneous acclimatization, effectively shortening the cultivation and acclimatization time of magnetically loaded activated sludge, reducing loss during magnetic powder addition, and lowering operating costs. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the overall magnetic loading activated sludge rapid cultivation system of the present invention;

[0029] Figure 2 This is a schematic diagram of the magnetically loaded activated sludge rapid cultivation system in Example 2.

[0030] In the diagram: 1. Wastewater pretreatment system; 2. Biological tank; 3. Aeration and mixing system; 4. Sedimentation tank; 5. Sludge return pump; 6. Magnetic powder pretreatment device; 7. Magnetic powder dosing device; 8. Water jet injector; 9. Aeration blower; 10. Flow mixer; 11. Microporous aerator; 12. Subsequent treatment unit; 13. Waste sludge pump; 14. Magnetic separator; 15. Anoxic tank. Detailed Implementation

[0031] The present invention will be further described below with reference to embodiments, but the scope of protection of the present invention is not limited to the scope described. Example 1

[0032] A small-scale domestic sewage treatment plant is used in a certain village, with a designed daily treatment capacity of 24 m³. The system adopts A. 2 The O process is designed to produce effluent that meets the Class A standard of the "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants" (GB 18918-2002).

[0033] 1) Inject small-scale domestic sewage from natural villages into the biological treatment tank 2 to 1 / 2 of the effective water depth, add sludge with 80% water content, the amount added is calculated as 10% of the effective tank volume, and then add nutrients such as flour, urea and phosphate fertilizer in the ratio of BOD5:N:P of 100:5:1. At the same time, turn on the aeration and stirring system 3 to aerate for 2 days, and then start the sludge return pump 5 to return the sludge.

[0034] 2) Add inoculation activated sludge and hydroxyl-activated magnetic powder to magnetic powder feeding device 7, and mix thoroughly and evenly using a stirrer at a speed of 150 rpm for 20 min.

[0035] 3) The sludge returned by the sludge return pump 5 is mixed evenly with the activated magnetic mud, and then the water jet 8 is used to add it at a constant speed to the return inlet of the biological tank 2, and it is stirred by the pusher mixer 12. During the magnetic powder addition, continuous aeration and the addition of nutrients are carried out for cultivation for 3 days.

[0036] 4) Continuously feed the wastewater to be treated into biological treatment tank 2 at 20% to 30% of the design flow rate, continuously stir and aerate, control the dissolved oxygen concentration at 2 to 3 mg / L, supplement the nutrients required for the activated sludge process, and regularly test the sludge concentration and effluent quality. After the test results meet the standards, gradually increase the amount of wastewater added to 50% of the volume of biological treatment tank 2, and continue the conditioning process as described above for 7 days.

[0037] 5) Continue to add nutrients and increase aeration, continue to add activated magnetic mud mixture, slowly increase the influent volume of domestic sewage to 70%, monitor the concentration of activated sludge in the system and the effluent quality of the sedimentation tank, for a period of 7 days;

[0038] 6) When the influent volume of domestic sewage increases to 100%, the magnetic powder dosage reaches 250 mg / g dry sludge, the concentration of activated sludge in the system reaches 6000 mg / L, and the effluent quality of sedimentation tank 4 meets the design requirements, the cultivation of magnetically loaded activated sludge is complete.

[0039] Table 1. Measured influent and effluent water quality indicators after stable operation (unit: mg / L)

[0040] Example 2

[0041] A wastewater treatment plant receives industrial wastewater and domestic sewage from within its premises, with a daily treatment capacity of 25,000–35,000 m³. The biological treatment stage uses A… 2 The main influent and effluent water qualities for the O process are shown in the table below:

[0042] Table 2. Main influent and effluent water quality indicators (unit: mg / L)

[0043]

[0044] The initial inoculation sludge was the excess sludge from sedimentation tank 4. After dewatering by a plate and frame filter press, a sludge cake with an 80% moisture content was formed. Because the influent water quality and sludge properties were similar, the sludge acclimatization period could be shortened. Magnetite powder with a particle size of 100 µm was used for magnetic loading of activated sludge, with a final addition concentration of 170 mg / g dry sludge.

[0045] like Figure 2 As shown, in this embodiment, biological tank 2 is an aerobic tank.

[0046] Add the wastewater to be treated to the facultative tank 15 and the aerobic tank to 2 / 3 of the effective water depth. The amount of inoculated sludge is 20% of the effective tank volume. Add nutrients at a BOD5:N:P ratio of 100:5:1. Start the aeration blower 9 and continuously aerate through the microporous aerator 13 for cultivation and acclimatization. During this period, inoculated sludge can be added in small amounts multiple times. Do not discharge sludge from the sedimentation tank 4. All sludge is returned at a return flow rate of 30% of the design value, increasing the sludge concentration to about 3200 mg / L for 5 days.

[0047] The activated magnetic powder and inoculated sludge are mixed evenly in the magnetic powder adding device 7 at a stirring speed of 120 rpm for 30 minutes. The magnetic sludge and returned sludge are then mixed via the sludge return pump 5 and added to the aerobic tank through the water jet injector 8. The push-flow agitator 11 is activated to promote flow and agitation, preventing the magnetic powder from settling. Magnetic sludge is added in 1-2 batches daily, along with nutrients in proportion, to continuously increase the activated sludge concentration to 6000 mg / L for 5 days.

[0048] Gradually increase the wastewater influent to 200% of the original design volume, and increase the magnetic powder dosage to 170 mg / g dry sludge. Continuously aerate and stir to control the DO value in the aerobic tank at 2-3 mg / L, increasing the sludge concentration to 9000 mg / L. The sludge return flow rate in sedimentation tank 4 reaches the design value, and the sludge discharge is controlled. The remaining sludge is pumped by pump 13 to the magnetic separator 14 to recover the magnetic powder for reuse in the magnetic powder dosing device 7. This process lasts for 10 days, after which the system reaches a stable operating state. Once the effluent quality from sedimentation tank 4 meets the design requirements, it enters the subsequent treatment unit 12, where the magnetically loaded activated sludge cultivation is complete.

Claims

1. A method for rapid cultivation of a magnetically loaded activated sludge, characterized by The magnetic loading activated sludge rapid cultivation system comprises a biochemical tank (2), one end of which is connected with a sewage pretreatment system (1) through a pipeline, the other end of which is connected with a sedimentation tank (4) through a pipeline, the bottom material outlet of the sedimentation tank (4) is connected with a sludge return pump (5) through a pipeline, the outlet of the sludge return pump (5) is connected with a water injector (8) through a pipeline, the water injector (8) is connected with the return inlet of the end of the biochemical tank (2) through a pipeline, and the bottom inlet of the water injector (8) is connected with a magnetic powder adding device (7); The method adopts the magnetic loading activated sludge rapid cultivation system and comprises the following steps: 1) sludge inoculation: injecting sewage to be treated into the biochemical tank (2), adding activated sludge, then adding nutrients, and starting the aeration and stirring system (3) to carry out aeration and stirring, controlling the dissolved oxygen in the biochemical tank (2) to be 1-2 mg / L, waiting for the sludge concentration to gradually increase to 1000-3000 mg / L, maintaining for 1-3 days, and then starting the sludge return pump (5) to carry out sludge return; 2) magnetic sludge activation: adding inoculated activated sludge and hydroxyl-activated magnetic powder into the magnetic powder adding device (7), and fully stirring and mixing the same through a stirrer; 3) magnetic powder adding: during continuous aeration of the biochemical tank (2), adding the activated magnetic sludge into the biochemical tank (2) through the magnetic powder adding device (7), the water injector (8) uniformly adds the mixed sludge and the activated magnetic sludge into the return inlet of the biochemical tank (2) at a constant speed, and a push-flow stirrer (10) is used for stirring, during the magnetic powder adding, continuous aeration and nutrient addition are carried out for cultivation, the dissolved oxygen in the biochemical tank (2) is controlled to be 1.5-2.5 mg / L, the SV30 and the MLSS are regularly detected, and the activated sludge concentration is continuously increased to 3000-4500 mg / L; 4) sludge domestication: continuously adding sewage to be treated into the biochemical tank (2) at 20%-30% of the design flow, continuously stirring and aeration, controlling the dissolved oxygen concentration to be 2-3 mg / L, supplementing the nutrients required by the activated sludge process, regularly detecting the sludge concentration and the effluent quality, and gradually increasing the sewage addition amount to 50% of the volume of the biochemical tank (2) after the detection results meet the standards, and continuing the domestication according to the foregoing until the sludge concentration and the effluent quality meet the standards; 5) sludge expansion: increasing the sludge return to the design value of the sedimentation tank (4), increasing the wastewater inflow to 70% of the design water amount, adding the activated magnetic sludge mixture into the biochemical tank (2) again, increasing the aeration amount to 2.5-4 mg / L, controlling the sludge discharge amount, gradually increasing the magnetic loading activated sludge concentration to 4500-8000 mg / L under the condition that the SS index of the effluent of the sedimentation tank (4) is less than 20 mg / L, and maintaining for 5-10 days. 6) Stable operation After step 5) is completed, the wastewater inflow is gradually increased to more than 100% of the design water quantity, the activated sludge concentration in the biochemical tank (2) is stabilized at 6000-9000 mg / L, the dissolved oxygen is controlled at 2-3 mg / L, the activated sludge in the biochemical tank (2) has good properties, the SV30 is 40-50%, the effluent of the sedimentation tank (4) is clear, and the effluent quality meets the design requirements, that is, the magnetic loading activated sludge cultivation is completed.

2. The method of claim 1, wherein the magnetic loading of the activated sludge is performed by using a magnetic field having a magnetic flux density of 0.1 T or more. The magnetic powder pretreatment device (6) is connected with the magnetic powder adding device (7) through a pipeline.

3. The method of claim 1, wherein the activated sludge is rapidly cultivated by magnetic loading. The residual sludge pump (13) is connected with the bottom material outlet of the sedimentation tank (4) through a pipeline, and the side inlet of the magnetic separator (14) is connected with the residual sludge pump (13) through a pipeline, and the bottom outlet of the magnetic separator (14) is connected with the magnetic powder adding device (7) through a pipeline.

4. The method for quick cultivation of magnetic loaded activated sludge according to claim 2 or 3, characterized in that The biochemical tank (2) is provided with an aeration stirring system (3), which includes an aeration fan (9), a microporous aerator (11) and a plug flow stirrer (10). The plug flow stirrer (10) is arranged at the top of the biochemical tank (2), the microporous aerator (11) is installed at the bottom of the biochemical tank (2), and the microporous aerator (11) cooperates with the aeration fan (9) to deliver oxygen to the inside of the biochemical tank (2) to meet the dissolved oxygen requirement of each stage of sludge cultivation.

5. The method of claim 1, wherein the magnetic loading of the activated sludge is performed by using a magnetic field of 0.1 T or more. In step 1), the activated sludge is 80% moisture content sludge cake, and the activated sludge dosage accounts for 10-20% of the volume of the biochemical tank (2); in step 2), the magnetic powder is micron-sized magnetic powder with Fe3O4 content not less than 95%, particle size distribution not less than 90% of 80-150 mesh, and the surface is treated with hydrogen peroxide or sodium hydroxide for hydroxylization and activation. The concentration of the magnetic powder is 150-170 mg / g of dry sludge.

6. The method of claim 1, wherein the magnetic loading of the activated sludge is performed by using a magnetic field of 0.1 T or more. In step 1), the sludge reflux pump (5) is started with a reflux ratio of 20%-30% to perform sludge reflux; according to the observation of the magnetic sludge combination, 1-2 batches of activated magnetic sludge are added every day to control the magnetic powder dosage to prevent excessive addition of magnetic powder from causing the magnetic powder to sink to the bottom, and the activated sludge concentration is continuously increased to 3000-4500 mg / L for 5-7 days.

7. The method of claim 1, wherein the activated sludge is rapidly cultivated by magnetic loading. In step 4), the nutrients required by the activated sludge process are supplemented according to the ratio of BOD5:N:P=100:5:1, the sludge concentration and effluent quality are regularly detected; the water temperature is controlled at 12-38℃ and the pH value is controlled at 6.5-8.5 to ensure the biochemical effect, and the wastewater addition amount is gradually increased to 50% of the volume of the biochemical tank (2); during the acclimation period, one batch of activated magnetic sludge is added every 1-2 days for 5-10 days.

8. The method of claim 1, wherein the magnetic loading is performed by using a magnetic field of 0.1 T to 0.5 T. In step 6), the sludge concentration is 7000-8000 mg / L, and the concentration of the magnetic powder is 150-170 mg / g of dry sludge.

9. The method of claim 1, wherein the magnetic loading is performed at a magnetic flux density of 0.1 to 0.5 T. In the sludge inoculation, magnetic sludge addition and sludge domestication stage, the sludge is not discharged, and the aeration and plug flow stirring are continuously carried out; in the sludge expansion stage, a small amount of sludge is discharged through the residual sludge pump (13), and the magnetic loading activated sludge concentration is continuously improved; in the stable operation stage, under the condition of ensuring the effluent water quality and activated sludge concentration, the residual sludge pump is normally discharged; the activated sludge process includes AO, A 2 O, oxidation ditch or SBR.

Images