Magnetic loading activated sludge rapid culture system and method

Abstract

The invention discloses a magnetic loading activated sludge rapid culture system and method.The system comprises a biochemical pool, a water inlet in one end of the biochemical pool is connected with a sewage treatment system, a water outlet in the other end of the biochemical pool is connected with a sedimentation pool, and a material outlet in the bottom of the sedimentation pool is connected with a sludge reflux pump; an outlet of the sludge reflux pump is connected with a water blaster, the water blaster is connected with a reflux inlet in the end part of the biochemical pool, and a bottom inlet of the water blaster is connected with a magnetic powder adding device; the rapid culture method for the magnetically loaded activated sludge comprises the stages of sludge inoculation, magnetic sludge activation, magnetic powder addition, sludge acclimation and stable operation, the whole culture period is controlled to be 20-35 days, the initial debugging and commissioning time of the magnetically loaded activated sludge process is shortened, and the discharge of residual sludge and unqualified wastewater is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage biological treatment, and in particular relates to a magnetic loading activated sludge rapid cultivation system and method. Background Art

[0002] The activated sludge process is one of the most common treatment processes in sewage treatment, especially in large and medium-sized sewage treatment plants, which generally adopt A 2 O, oxidation ditch and other activated sludge treatment technologies. However, the conventional activated sludge process has the disadvantages of large floor space occupied by civil construction structures, weak system load resistance, large residual sludge output, and sludge leakage in the secondary sedimentation tank. In view of these shortcomings, adding fillers to the biochemical pool to increase sludge concentration and impact resistance is the main direction of the activated sludge process improvement. The magnetic loading activated sludge method is an improved technology developed on this basis, that is, by adding magnetic powder to the activated sludge, the activated sludge flocs are adsorbed and bonded to the surface of the magnetic powder, and a more compact floc is formed under the action of the magnetic field, which greatly improves the sludge sedimentation performance, thereby achieving better mud-water separation effect, greatly reducing the volume of the bioreactor and sedimentation tank, and improving the treatment load and nitrogen and phosphorus removal effects.

[0003] In the prior art, magnetic powder is usually added directly to the biochemical pool for cultivation and domestication to obtain high-concentration magnetically loaded activated sludge. However, in the actual cultivation process, there are problems such as long cultivation time of magnetically loaded activated sludge, poor initial sludge and magnetic powder binding, and serious loss of magnetic powder during the addition process.

[0004] Therefore, it is necessary to propose a more economical, efficient and easy-to-operate magnetic loading activated sludge rapid cultivation method to shorten the sludge cultivation and acclimatization cycle, increase the sludge concentration and achieve good treatment effects. Summary of the invention

[0005] In view of the problems existing in the prior art, the object of the present invention is to provide a magnetic loading activated sludge rapid cultivation system and method for sludge cultivation and domestication in the initial stage of commissioning of the magnetic loading activated sludge system.

[0006] To achieve the above object, the technical solution of the present invention is as follows: The present invention proposes a magnetically loaded activated sludge rapid cultivation system, which is characterized by comprising a biochemical pool, wherein a water inlet at one end of the biochemical pool is connected to a sewage treatment system through a pipeline, and a water outlet at the other end is connected to a sedimentation tank through a pipeline, a material outlet at the bottom of the sedimentation tank is connected to a sludge return pump through a pipeline, an outlet of the sludge return pump is connected to an ejector through a pipeline, the ejector is connected to a reflux inlet at the end of the biochemical pool through a pipeline, and a magnetic powder dosing device is connected to the bottom inlet of the ejector.

[0007] Furthermore, it comprises a magnetic powder pretreatment device, and the magnetic powder pretreatment device is connected to the magnetic powder adding device through a pipeline.

[0008] Furthermore, it comprises a residual sludge pump and a magnetic separator, wherein the residual sludge pump is connected to the material outlet at the bottom of the sedimentation tank through a pipeline, the side inlet of the magnetic separator is connected to the residual sludge pump through a pipeline, and the bottom outlet of the magnetic separator is connected to the magnetic powder dosing device through a pipeline.

[0009] Furthermore, an aeration and stirring system is provided in the biochemical pool, and the aeration and stirring system includes an aeration fan, a microporous aerator and a plug flow agitator. The plug flow agitator is arranged at the top of the biochemical pool, and the microporous aerator is installed at the bottom of the biochemical pool. The microporous aerator cooperates with the aeration fan to transport oxygen to the inside of the biochemical pool to meet the dissolved oxygen demand at each stage of sludge culture.

[0010] The present invention also proposes a magnetic loading activated sludge rapid cultivation method, the method adopts a magnetic loading activated sludge rapid cultivation system, and the method comprises the following steps: 1) Sludge inoculation: Inject the sewage to be treated into the biochemical pool, add activated sludge, and then add nutrients. At the same time, start the aeration and stirring system for aeration, control the dissolved oxygen in the biochemical pool to 1-2 mg / L, and wait for the sludge concentration to gradually increase to 1000-3000 mg / L, maintain for 1-3 days, and then start the sludge return pump for sludge return; 2) Magnetic mud activation: Add the activated sludge for inoculation and the hydroxyl-activated magnetic powder to the magnetic powder dosing device, and stir and mix them thoroughly with the agitator; 3) Magnetic powder addition: During the continuous aeration period of the biochemical pool, activated magnetic mud is added through the magnetic powder adding device. The water ejector uniformly adds the mixed return sludge and activated magnetic mud to the return inlet of the biochemical pool and stirs it through the plug flow agitator. During the magnetic powder addition period, continuous aeration and nutrient addition are performed for cultivation. The dissolved oxygen in the biochemical pool is controlled to be 1.5-2.5 mg / L. SV30 and MLSS are tested regularly to continuously increase the activated sludge concentration to 3000-4500 mg / L. 4) Sludge training: 20% to 30% of the designed flow rate is used to continuously feed the treated sewage into the biochemical pool, with continuous stirring and aeration, and the dissolved oxygen concentration is controlled at 2 to 3 mg / L. The nutrients required for the activated sludge process are supplemented, and the sludge concentration and effluent water quality are tested regularly. When the test results meet the standards, the amount of sewage added is gradually increased to 50% of the volume of the biochemical pool, and the training is continued as described above until the sludge concentration and effluent water quality meet the standards; 5) Sludge expansion: Increase the sludge return of the sedimentation tank to the design value, and at the same time increase the wastewater inflow to 70% of the design water volume, add the activated magnetic mud mixture to the biochemical pool again, increase the aeration volume to 2.5-4 mg / L, control the sludge discharge, and ensure that the SS index of the sedimentation tank effluent is less than 20 mg / L. Then gradually increase the concentration of magnetically loaded activated sludge to 4500-8000 mg / L for 5-10 days; 6) Stable operation After step 5) is completed, the wastewater inflow gradually increases to more than 100% of the designed water volume, the activated sludge concentration in the biochemical pool is stabilized at 6000~9000 mg / L, the dissolved oxygen is controlled at 2~3 mg / L, the activated sludge in the biochemical pool has good properties, SV30 is 40~50%, the effluent from the sedimentation tank is clear, and the effluent water quality meets the design requirements, that is, the magnetic loading activated sludge cultivation is completed.

[0011] Furthermore, in step 1), activated sludge uses mud cake with a moisture content of 80%, and the amount of activated sludge added accounts for 10-20% of the volume of the biochemical pool; in step 2), magnetic powder uses micron-grade magnetic powder with a Fe3O4 content of not less than 95%, and the particle size distribution of 80-150 mesh accounts for not less than 90%, and its surface is activated by hydroxylation treatment with hydrogen peroxide or sodium hydroxide, and the magnetic powder concentration is 150-170 mg / g dry sludge.

[0012] Further, step 1) starts the sludge return pump at a return ratio of 20% to 30% to return the sludge; according to the combination of magnetic mud under microscopic examination, the amount of magnetic powder added is controlled to prevent the magnetic powder from sinking to the bottom due to excessive addition. Add 1 to 2 batches of activated magnetic mud every day for 5 to 7 days to continuously increase the concentration of activated sludge to 3000 to 4500 mg / L.

[0013] Furthermore, in step 4), the nutrients required for the activated sludge process are supplemented at a ratio of BOD5:N:P=100:5:1, and the sludge concentration and effluent water quality are regularly tested; the inlet temperature is controlled at 12-38°C and the pH value is 6.5-8.5, and the amount of sewage added is gradually increased to 50% of the volume of the biochemical pool while ensuring the biochemical effect; during the acclimation period, a batch of activated magnetic mud is added every 1-2 days for 5-10 days.

[0014] Furthermore, in step 6), the sludge concentration is 7000-8000 mg / L, and the magnetic powder concentration is 150-170 mg / g dry sludge.

[0015] Furthermore, no sludge is discharged during the sludge inoculation, magnetic sludge addition and sludge acclimation stages, and aeration and plug flow stirring are continuously performed; a small amount of sludge is discharged through the residual sludge pump during the sludge expansion stage to continuously increase the concentration of magnetically loaded activated sludge; during the stable operation stage, the residual sludge pump is used to discharge sludge normally while ensuring the effluent water quality and activated sludge concentration; the activated sludge includes AO, A2 O, oxidation ditch or SBR.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1) The magnetic loading activated sludge rapid cultivation method of the present invention has gone through the stages of sludge inoculation, magnetic sludge activation, magnetic powder addition, sludge training and stable operation. The entire cultivation cycle is controlled within 20 to 35 days, shortening the initial commissioning and operation time of the magnetic loading activated sludge process and reducing the discharge of excess sludge and unqualified wastewater; 2) The system of the present invention uses the Bernoulli effect to mix the activated magnetic mud with the return sludge through the water ejector arranged at the outlet of the sludge return pump, and uniformly adds it to the return inlet of the biochemical pool to cultivate the sludge, thereby avoiding the problems of poor binding degree between the initial sludge and the magnetic powder, serious loss of the magnetic powder during the addition process, and long cultivation time; 3) The present invention is applicable to the magnetic loading activated sludge cultivation of various magnetic biochemical sewage treatment systems, realizes the organic combination of magnetic sludge through magnetic powder activation, realizes the uniform addition of magnetic sludge through the ejector of the sludge return pipe, forms high-concentration activated sludge by loading biofilm and stabilizing flocs on the surface of magnetic powder, and realizes better biochemical treatment effect; 4) The present invention adopts low-load continuous cultivation, combined with continuous and uniform addition of magnetic mud, to increase the concentration of activated sludge and magnetic powder in the biochemical pool while increasing the amount of sewage added for synchronous domestication, effectively shortening the cultivation and domestication time of magnetically loaded activated sludge, reducing the loss during the addition of magnetic powder, and reducing operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is an overall schematic diagram of the magnetic loading activated sludge rapid cultivation system of the present invention; Figure 2 This is a schematic diagram of the magnetically loaded activated sludge rapid cultivation system in Example 2.

[0018] In the figure: 1. Sewage pretreatment system; 2. Biochemical pool; 3. Aeration and stirring system; 4. Sedimentation tank; 5. Sludge return pump; 6. Magnetic powder pretreatment device; 7. Magnetic powder dosing device; 8. Water ejector; 9. Aeration fan; 10. Plug flow agitator; 11. Microporous aerator; 12. Subsequent treatment unit; 13. Residual sludge pump; 14. Magnetic separator; 15. Aeration tank. DETAILED DESCRIPTION

[0019] The present invention will be further described below in conjunction with embodiments, but the scope of protection of the present invention is not limited to the described scope. Example 1

[0020] A small domestic sewage treatment plant is used in a natural village with a designed daily treatment capacity of 24m³. The system adopts A 2O process, the designed effluent meets the Class A standard of Pollutant Discharge Standard for Urban Wastewater Treatment Plants (GB 18918-2002).

[0021] 1) Inject small-scale domestic sewage from natural villages into the biochemical pool 2 to 1 / 2 of the effective water depth, add sludge with a water content of 80%, and the amount added is calculated as 10% of the effective pool capacity, and then add flour, urea, and phosphate fertilizer nutrients at a ratio of BOD5:N:P of 100:5:1, and at the same time start the aeration and stirring system 3 for 2 days, and then start the sludge return pump 5 for sludge return; 2) Adding the activated sludge for inoculation and the hydroxyl-activated magnetic powder to the magnetic powder dosing device 7, stirring and mixing them evenly by a stirrer, the stirrer speed is 150 rpm, and the mixing time is 20 minutes; 3) The sludge returned by the sludge return pump 5 is mixed evenly with the activated magnetic mud, and then added to the return inlet of the biochemical pool 2 at a uniform speed by the water ejector 8, and stirred by the plug flow agitator 12. During the addition of magnetic powder, continuous aeration and nutrient addition are performed for cultivation for 3 days; 4) Continuously add the treated sewage to the biochemical pool 2 at 20% to 30% of the design flow rate, continue stirring and aerating, control the dissolved oxygen concentration to 2 to 3 mg / L, supplement the nutrients required for the activated sludge process, regularly test the sludge concentration and effluent quality, and when the test results meet the standards, gradually increase the amount of sewage added to 50% of the volume of the biochemical pool 2, and continue the training as mentioned above for 7 days; 5) Continue to add nutrients and increase aeration, continue to add activated magnetic mud mixture, slowly increase the domestic sewage inflow to 70%, monitor the system activated sludge concentration and sedimentation tank effluent quality, and continue for 7 days; 6) When the domestic sewage inflow increases to 100%, the magnetic powder dosage reaches 250 mg / g dry sludge, the activated sludge concentration in the system reaches 6000 mg / L, and the effluent quality of sedimentation tank 4 meets the design requirements, the magnetic loading activated sludge cultivation is completed.

[0022] Table 1 Measured inlet and outlet water quality indicators after stable operation (unit: mg / L) Example 2

[0023] A sewage treatment plant receives industrial wastewater and domestic sewage from the plant area, with an average daily treatment volume of 25,000 to 35,000 m³. The biochemical section uses A 2 O process, the main inlet and outlet water quality is shown in the following table: Table 2 Main inlet and outlet water quality indicators (unit: mg / L)

[0024] First, the inoculated sludge was drawn from the residual sludge in the sedimentation tank 4, and after dehydration by the plate and frame filter press, a mud cake with a moisture content of 80% was formed. Since the influent water quality and sludge properties were similar, the sludge acclimation period could be shortened. The magnetic loading activated sludge culture used ferroferric oxide magnetic powder, with a particle size of 100 µm, and the final addition concentration was 170 mg / g dry sludge.

[0025] like Figure 2 As shown, in this embodiment, the biochemical pool 2 is an aerobic pool. Add the wastewater to be treated to the aerobic 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 capacity, and the nutrients are added according to the BOD5:N:P ratio of 100:5:1, and the aeration fan 9 is started to continuously aerate through the microporous aerator 13 for cultivation and domestication. During this period, the inoculated sludge can be added several times in small amounts, the sedimentation tank 4 does not discharge the sludge temporarily, and all the sludge is returned. The return amount is 30% of the design value, and the sludge concentration is increased to about 3200 mg / L, and the duration is 5 days; The activated magnetic powder and the inoculated sludge are mixed and stirred evenly in the magnetic powder dosing device 7, with the agitator speed of 120rpm and the mixing time of 30min. The magnetic mud and the return sludge are mixed by the sludge return pump 5 through the water ejector 8 and added to the aerobic tank, and the plug flow agitator 11 is started for plug flow stirring to prevent the magnetic powder from sinking to the bottom. Magnetic mud is added in 1 to 2 batches every day, and nutrients are added in proportion to continuously increase the concentration of activated sludge to 6000 mg / L for 5 days; The sewage inflow was gradually increased to 200% of the original design water volume, the magnetic powder dosage was increased to 170 mg / g dry sludge, the aerobic tank DO value was controlled at 2-3 mg / L by continuous aeration and stirring, and the sludge concentration was increased to 9000 mg / L. The sludge return volume of sedimentation tank 4 reached the design value, the sludge discharge volume was controlled, and the residual sludge pump 13 was lifted to the magnetic separator 14 to recover the magnetic powder and reuse it in the magnetic powder dosing device 7. The duration was 10 days, and the system operation entered a stable state. After monitoring the effluent quality of sedimentation tank 4 to meet the design requirements, it entered the subsequent treatment unit 12, and the magnetic loading activated sludge culture was completed.

Claims

1. A magnetic loading activated sludge rapid cultivation system, characterized in that The biochemical pool (2) comprises a water inlet at one end of the biochemical pool (2) connected to a sewage treatment system (1) via a pipeline, a water outlet at the other end of the biochemical pool (2) connected to a sedimentation tank (4) via a pipeline, a material outlet at the bottom of the sedimentation tank (4) connected to a sludge return pump (5) via a pipeline, an outlet of the sludge return pump (5) connected to a water ejector (8) via a pipeline, the water ejector (8) connected to a return inlet at the end of the biochemical pool (2) via a pipeline, and a magnetic powder dosing device (7) connected to the bottom inlet of the water ejector (8).

2. A magnetic loading activated sludge rapid cultivation system according to claim 1, characterized in that It comprises a magnetic powder pretreatment device (6), wherein the magnetic powder pretreatment device (6) is connected to a magnetic powder dosing device (7) via a pipeline.

3. A magnetic loading activated sludge rapid cultivation system according to claim 1, characterized in that It comprises a surplus sludge pump (13) and a magnetic separator (14), wherein the surplus sludge pump (13) is connected to a material outlet at the bottom of a sedimentation tank (4) via a pipeline, a side inlet of the magnetic separator (14) is connected to the surplus sludge pump (13) via a pipeline, and a bottom outlet of the magnetic separator (14) is connected to a magnetic powder dosing device (7) via a pipeline.

4. A magnetic loading activated sludge rapid culture system according to claim 2 or 3, characterized in that An aeration and stirring system (3) is provided in the biochemical pool (2), and the aeration and stirring system (3) comprises an aeration fan (9), a microporous aerator (11) and a plug flow agitator (10), wherein the plug flow agitator (10) is arranged at the top of the biochemical pool (2), and the microporous aerator (11) is installed at the bottom of the biochemical pool (2). The microporous aerator (11) cooperates with the aeration fan (9) to transport oxygen into the biochemical pool (2) to meet the dissolved oxygen demand at various stages of sludge cultivation.

5. A method for rapid cultivation of magnetically loaded activated sludge, characterized in that The method adopts the magnetic loading activated sludge rapid cultivation system according to any one of claims 1 to 4, and the method comprises the following steps: 1) Sludge inoculation: Inject the sewage to be treated into the biochemical pool (2), add activated sludge, and then add nutrients. At the same time, start the aeration and stirring system (3) to perform aeration. Control the dissolved oxygen in the biochemical pool (2) to be 1-2 mg / L. Wait for the sludge concentration to gradually increase to 1000-3000 mg / L and maintain it for 1-3 days. Then start the sludge return pump (5) to return the sludge. 2) Magnetic mud activation: adding the activated sludge for inoculation and the hydroxyl-activated magnetic powder to the magnetic powder dosing device (7), and stirring and mixing them thoroughly with a stirrer; 3) Adding magnetic powder: During the continuous aeration period of the biochemical pool (2), activated magnetic mud is added through the magnetic powder adding device (7), and the water ejector (8) uniformly adds the mixed return sludge and the activated magnetic mud to the return inlet of the biochemical pool (2), and stirs them through the plug flow stirrer (10). During the addition of magnetic powder, continuous aeration and nutrient addition are performed for cultivation. The dissolved oxygen in the biochemical pool (2) is controlled to be 1.5-2.5 mg / L, and the SV30 and MLSS are regularly tested to continuously increase the activated sludge concentration to 3000-4500 mg / L. 4) Sludge conditioning: 20% to 30% of the designed flow rate is continuously fed into the biochemical tank (2) with sewage to be treated. The sewage is continuously stirred and aerated to control the dissolved oxygen concentration to 2 to 3 mg / L. The nutrients required for the activated sludge process are supplemented. The sludge concentration and effluent quality are tested regularly. When the test results meet the standards, the amount of sewage added is gradually increased to 50% of the volume of the biochemical tank (2). The conditioning is continued as described above until the sludge concentration and effluent quality meet the standards. 5) Sludge expansion: Increase the sludge return of sedimentation tank (4) to the design value, increase the wastewater inflow to 70% of the design water volume, add the activated magnetic mud mixture to the biochemical tank (2) again, increase the aeration volume to 2.5-4 mg / L, control the sludge discharge, ensure that the SS index of the effluent of sedimentation tank (4) is less than 20 mg / L, and gradually increase the concentration of magnetically loaded activated sludge to 4500-8000 mg / L for 5-10 days; 6) Stable operation After step 5) is completed, the wastewater inflow gradually increases to more than 100% of the designed water volume, the activated sludge concentration in the biochemical pool (2) is stabilized at 6000-9000 mg / L, the dissolved oxygen is controlled at 2-3 mg / L, the activated sludge in the biochemical pool (2) has good properties, SV30 is 40-50%, the effluent from the sedimentation tank (4) is clear, and the effluent water quality meets the design requirements, that is, the magnetic loading activated sludge cultivation is completed.

6. A magnetic loading activated sludge rapid cultivation method according to claim 5, characterized in that In step 1), activated sludge uses a mud cake with a moisture content of 80%, and the amount of activated sludge added accounts for 10-20% of the volume of the biochemical pool (2); in step 2), magnetic powder uses micron-grade magnetic powder with a Fe3O4 content of not less than 95%, and the particle size distribution is not less than 90% in the range of 80-150 mesh. The surface of the magnetic powder is activated by hydroxylation treatment with hydrogen peroxide or sodium hydroxide, and the concentration of the magnetic powder is 150-170 mg / g dry sludge.

7. The method for rapid cultivation of activated sludge by magnetic loading according to claim 5, characterized in that Step 1) starting the sludge return pump (5) at a return ratio of 20% to 30% to return the sludge; adding 1 to 2 batches of activated magnetic mud every day according to the magnetic mud binding situation under microscopic examination, controlling the amount of magnetic powder added to prevent the magnetic powder from settling to the bottom due to excessive addition, maintaining for 5 to 7 days, and continuously increasing the activated sludge concentration to 3000 to 4500 mg / L.

8. The method for rapid cultivation of activated sludge by magnetic loading according to claim 5, characterized in that Step 4) Supplement the nutrients required for the activated sludge process at a ratio of BOD5:N:P=100:5:1, and regularly test the sludge concentration and effluent quality; control the inlet water temperature to 12-38°C and the pH value to 6.5-8.5, and gradually increase the amount of sewage added to 50% of the volume of the biochemical pool (2) while ensuring the biochemical effect; during the acclimatization period, add a batch of activated magnetic mud every 1-2 days for 5-10 days.

9. The method for rapid cultivation of activated sludge by magnetic loading according to claim 5, characterized in that In step 6), the sludge concentration is 7000-8000 mg / L, and the magnetic powder concentration is 150-170 mg / g dry sludge.

10. The method for rapid cultivation of activated sludge by magnetic loading according to claim 5, characterized in that During the sludge inoculation, magnetic sludge addition and sludge acclimation stages, no sludge is discharged, and aeration and plug flow stirring are continuously performed; during the sludge expansion stage, a small amount of sludge is discharged through the residual sludge pump (13) to continuously increase the concentration of magnetically loaded activated sludge; during the stable operation stage, while ensuring the effluent water quality and activated sludge concentration, the sludge is discharged normally through the residual sludge pump; the activated sludge includes AO, A 2 O, oxidation ditch or SBR.

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