Soft-magnetic magnetic carrier activated sludge sewage treatment method

Abstract

The application discloses a soft-magnetic magnetic carrier activated sludge sewage treatment method, which comprises the following steps: pre-mixing activated sludge and pre-magnetized soft-magnetic magnetic powder; treating sewage by adopting SBR process to the pre-mixed magnetic carrier activated sludge; sampling supernatant to determine biochemical indexes at the end of a running period; recycling the magnetic powder by using a strong magnetic field during sludge discharge at the end of each running period, and pre-mixing the magnetic powder with activated sludge again; in the application, the soft-magnetic magnetic powder (FeSiAl) is quickly demagnetized after being magnetized, and the magnetic powder cannot be massively agglomerated; by using the characteristic, the soft-magnetic magnetic carrier activated sludge operation system can recycle the magnetic powder by using a strong magnetic field after sludge discharge, and the magnetic powder is added into activated sludge again, so that the stable combination of the magnetic powder and sludge floc is ensured; compared with the hard-magnetic magnetic carrier activated sludge method, the magnetic carrier activated sludge method with the loaded soft-magnetic magnetic powder can realize the recycling of the magnetic powder, greatly reduces the consumption of the magnetic powder, saves economic cost, and improves operation efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the sewage treatment technical field, specifically relates to a soft magnetic (FeSiAl) magnetic carrier activated sludge sewage treatment method. BACKGROUND

[0002] At present, the activated sludge method is the main method of sewage treatment, and has been widely applied in the world. However, the ordinary activated sludge method has the shortcomings of poor system impact resistance, easy sludge bulking, sludge aging and the like. The magnetic carrier activated sludge method is a modification of the traditional activated sludge method process, by adding hard magnetic powder (mainly Fe3O4) in the activated sludge sewage treatment process, using the electrically neutral property to realize the adsorption of the magnetic powder on the sludge floc, so that the floc structure is more compact, the sludge settling performance is greatly improved, the biomass in the reaction tank is improved, and the pollutant removal effect is improved. However, in the sludge discharge process of the running system, the magnetic powder recovery is involved, after the magnetic powder is recovered by using a strong magnetic field, due to the difficulty in demagnetization of the hard magnetic powder, when the recovered magnetic powder is put into the activated sludge system again, the magnetic powder particles are in a large-area agglomeration state, which is not conducive to the combination of the magnetic powder and the sludge floc, so that the magnetic powder can only be used once, and the repeated utilization rate of the magnetic powder is limited. If the magnetic powder is to be reused, a special demagnetization treatment equipment needs higher investment and energy consumption, resulting in high operation cost. SUMMARY

[0003] In view of the problems in the prior art, the present application provides a soft magnetic (FeSiAl) magnetic carrier activated sludge sewage treatment method.

[0004] The technical scheme of the present application is as follows:

[0005] A soft magnetic magnetic carrier activated sludge sewage treatment method, comprising:

[0006] Step 1, pre-mixing the activated sludge with pre-magnetized soft magnetic powder;

[0007] The soft magnetic powder is FeSiAl, and the pre-magnetization condition is a magnetic field of 2000-3000GS, and the pre-magnetization time is 5-10min;

[0008] The pre-mixing is in the form of mechanical stirring, the stirring speed is 220-260r / min, and the stirring time is 15-25min;

[0009] Based on 1L of activated sludge, 500-700mg / L of pre-magnetized soft magnetic powder is added in batches; the mixing of the magnetic powder and the sludge is observed by a microscope, and if there is no magnetic powder deposition at the bottom of the sludge, it is considered that the mixing is complete;

[0010] Step 2, the pre-mixed magnetic carrier activated sludge is used to treat sewage by using the SBR (sequencing batch activated sludge method) process;

[0011] The reaction device adopts the process of water inlet-aeration-precipitation-drainage; wherein, the aeration is 8-12h, and the precipitation is 1-2h; in the aeration stage, the disc type aeration is adopted, the DO (dissolved oxygen) is maintained at 1-3mg / L, and the mechanical stirring is added for the plug flow; the speed of the mechanical stirring is 150-180r / min, which can ensure that the sludge flows uniformly in the aeration tank, the dissolved oxygen diffuses uniformly in the aeration tank, the aeration flow is kept at 0.1-0.3L / min, and the appropriate dissolved oxygen concentration is ensured;

[0012] The water inlet volume and the sludge volume are kept at 1:1.5-1:1, which can keep the appropriate sludge load, avoid the sludge aging and sludge disintegration;

[0013] The pH of the sewage is kept at 7-8.5 during the whole operation period, the neutral environment can keep the activity of the microorganism, and the normal metabolism growth of the sludge floc is ensured; if the pH is low, the magnetic powder will react and dissolve in the acid environment, and the sludge floc will also be inactivated and disintegrated, and the magnetic powder cannot be combined with the sludge floc;

[0014] The sludge concentration is monitored regularly during the operation process, and the magnetic powder supplement amount is adjusted according to the sludge growth amount;

[0015] Step 3, at the end of the operation period, the supernatant is sampled to measure the biochemical indexes;

[0016] The biochemical indexes include the chemical oxygen demand and the TN (total nitrogen) concentration;

[0017] Step 4, at the end of each operation period, the magnetic powder is recycled by using the strong magnetic field during the sludge discharge process, and is re-inputted into step 1 to be premixed with the activated sludge;

[0018] The magnetic field strength for recycling the magnetic powder is 2000-3000GS.

[0019] The technical principle of the application is as follows:

[0020] The soft magnetic powder (FeSiAl) adopted in the application has the advantages of easy demagnetization, specifically, no large-area magnetic powder agglomeration phenomenon after magnetization, and can ensure the magnetic mud binding efficiency. In the hysteresis loop test, the saturation magnetization of the magnetic powder is 116.25 emu / g, which proves that the material has a high degree of sensitivity to the magnetic field and has the properties of the magnetic powder. When the magnetic active sludge system is running, the active sludge loaded with soft magnetic (FeSiAl) is different from the active sludge loaded with hard magnetic (Fe3O4), and the magnetic powder can be recycled when the sludge is discharged. The soft magnetic powder is easy to demagnetize after magnetization, and the magnetic active sludge running system can recycle the magnetic powder, avoiding the two defects that the hard magnetic powder (Fe3O4) is difficult to demagnetize and large-area agglomeration after recycling, and is difficult to combine with the sludge floc, which leads to the recycling of the magnetic powder and the stable operation of the magnetic active sludge system. The soft magnetic powder (FeSiAl) is loaded in the active sludge, which not only improves the removal rate of COD and ammonia nitrogen, but also improves the recyclability of the magnetic powder.

[0021] The application has the following beneficial effects:

[0022] The soft magnetic powder is different from the hard magnetic, and the soft magnetic powder is easy to demagnetize after magnetization, and the magnetic powder will not be large-area agglomeration. By using this characteristic, the soft magnetic active sludge running system can recycle the magnetic powder by using a strong magnetic field after discharging the sludge, and the magnetic powder can be added to the active sludge again, so as to ensure the stable combination of the magnetic powder and the sludge floc. Compared with the hard magnetic active sludge method, the soft magnetic active sludge method loaded with the soft magnetic powder (FeSiAl) can realize the recycling of the magnetic powder, greatly reduce the consumption of the magnetic powder, save the economic cost, and improve the operation efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The soft magnetic (FeSiAl) magnetic active sludge sewage treatment method flow chart of the application.

[0024] Figure 2 The agglomeration comparison of the hard magnetic powder before and after magnetization (left is before magnetization, right is after magnetization).

[0025] Figure 3 The agglomeration comparison of the soft magnetic powder before and after magnetization (left is before magnetization, right is after magnetization). DETAILED DESCRIPTION

[0026] The application will be further described below in combination with the embodiments. The following embodiments are only used to help understand the application. It should be pointed out that those skilled in the art can make several modifications to the application without departing from the principle of the application, and these improvements and modifications also fall within the protection scope of the claims of the application.

[0027] In the following examples, the soft magnetic powder (FeSiAl) and the hard magnetic powder (Fe3O4) have the specific information shown in Table 1.

[0028] Table 1

[0029] Magnetic powder type Particle size (pm) Model Manufacturer Soft magnetic powder (FeSiAl) 50 Titd-PFSA Shijiazhuang Liangfeng Alloy Hard magnetic magnetic powder (Fe3O4) 50 Fe304-1 Jinan Wu-8 Scientific Metal

[0030] The actual composition of the simulated sewage is as follows: glucose: 1400 mg / L; ammonium carbonate: 369 mg / L; sodium dihydrogen phosphate: 140 mg / L; magnesium sulfate: 67 mg / L; calcium chloride: 133 mg / L; and sodium carbonate: 521 mg / L.

[0031] The source of the actual printing and dyeing wastewater is the pretreated wastewater from the wastewater centralized treatment center of the Sanjian Group.

[0032] The source and type of activated sludge are the activated sludge in the aerobic tank of the wastewater centralized treatment center of the Sanjian Group.

[0033] The parameters of the activated sludge are as follows: sludge concentration: 2-3 g / L; dissolved oxygen (DO): 1-3 mg / L; and pH: 7-8.

[0034] Example 1

[0035] As shown in the following method, the method comprises: Figure 1

[0036] (1) 1L of the activated sludge containing 500 mg / L of the pre-magnetized soft magnetic powder (FeSiAl) after premixing is placed in an aeration tank.

[0037] (2) The simulated sewage is used as the object, the water volume and the sludge volume are kept at 1:1, the SBR process is adopted, the reaction device adopts the process of water inlet-aeration-settling-drainage, the aeration time is 12 h, the settling time is 1 h, the disc aeration is adopted in the aeration stage, the DO is maintained at 1-3 mg / L, and the mechanical stirring is used as the flow action.

[0038] (3) After the operation cycle is completed, the supernatant is sampled from the drainage, and the potassium dichromate method (HJ828-2017) is used for analysis.

[0039] (4) The magnetic powder is recovered when the sludge is discharged, and is premixed with the activated sludge again.

[0040] Comparative Example 1

[0041] (1) 1L of the activated sludge containing 500 mg / L of the pre-magnetized hard magnetic Fe3O4 powder after premixing and 1L of the blank activated sludge are respectively placed in an aeration tank, the mechanical stirring is adopted, and the stirring speed of 160 r / min is selected.

[0042] ​(2) Using simulated wastewater as the object, the influent volume and sludge volume are kept at 1:1. The SBR process is adopted. The reaction device adopts the process of influent-aeration-sedimentation-drainage, with aeration for 12 hours and sedimentation for 1 hour. During the aeration stage, disc aeration is used, DO is maintained at 1-3 mg / L, and mechanical stirring is used as the propulsion effect.

[0043] (3) After the operation cycle ends, take a sample of the supernatant of the drainage and use the potassium dichromate method (HJ828-2017) for analysis.

[0044] (4) Magnetic powder is recovered during sludge discharge and remixed with activated sludge.

[0045] The COD removal rate is shown in Table 2.

[0046] Table 2

[0047]

[0048] Example 2:

[0049] (1) Place 1L of premixed activated sludge containing 500mg / L of pre-magnetized soft magnetic powder (FeSiAl) into an aeration tank.

[0050] (2) Using simulated wastewater as the object, the influent volume and sludge volume are kept at 1:1. The SBR process is adopted. The reaction device adopts the process of influent-aeration-sedimentation-drainage, with aeration for 12 hours and sedimentation for 1 hour. During the aeration stage, disc aeration is used, DO is maintained at 1-3 mg / L, and mechanical stirring is used as the propulsion effect.

[0051] (3) After the operation cycle ends, a sample of the supernatant of the drainage is taken and the analytical method is alkaline potassium persulfate digestion ultraviolet spectrophotometry (HJ 636—2012).

[0052] (4) Magnetic powder is recovered during sludge discharge and remixed with activated sludge.

[0053] Comparative Example 2:

[0054] Similar to the steps in Example 2, the sludge consisted of a blank without magnetic powder and an activated sludge containing 500 mg / L pre-magnetized hard magnetic Fe3O4 powder.

[0055] The total nitrogen removal rate is shown in Table 3.

[0056] Table 3

[0057]

[0058] Example 3:

[0059] The magnetic powder from Example 2 is recovered and then added in this example.

[0060] (1) The 1L of activated sludge containing 500mg / L of pre-magnetized soft magnetic powder (FeSiAl) was placed in an aeration tank.

[0061] (2) The actual printing and dyeing wastewater was used as the object, the water volume and the sludge volume were kept at 1:1, the SBR process was used, the water inlet-aeration-settling-drainage process was used in the reaction device, the aeration time was 12h, the settling time was 1h, the disc aeration was used in the aeration stage, the DO was maintained at 1-3mg / L, and the mechanical stirring was used as the flow action.

[0062] (3) After the end of the operation cycle, the supernatant was sampled, and the analysis method was the alkaline potassium persulfate digestion ultraviolet spectrophotometry (HJ 636-2012).

[0063] (4) The magnetic powder was recovered when the sludge was discharged, and was pre-mixed with the activated sludge again.

[0064] Comparative Example 3:

[0065] The sludge was the same as that in step of Example 3, which was the activated sludge without magnetic powder as a blank and the activated sludge loaded with 500mg / L of recovered magnetized hard magnetic Fe3O4 magnetic powder.

[0066] The total nitrogen removal rate is shown in Table 4.

[0067] Table 4

[0068]

[0069] Example 4:

[0070] The magnetic powder recovered in Example 1 was put into the magnetic powder in this example.

[0071] (1) The 1L of activated sludge containing 500mg / L of pre-magnetized soft magnetic powder (FeSiAl) was placed in an aeration tank.

[0072] (2) The actual printing and dyeing wastewater was used as the object, the water volume and the sludge volume were kept at 1:1, the SBR process was used, the water inlet-aeration-settling-drainage process was used in the reaction device, the aeration time was 12h, the settling time was 1h, the disc aeration was used in the aeration stage, the DO was maintained at 1-3mg / L, and the mechanical stirring was used as the flow action.

[0073] (3) After the end of the operation cycle, the supernatant was sampled, and the analysis method was the potassium dichromate method (HJ828-2017).

[0074] (4) The magnetic powder was recovered when the sludge was discharged, and was pre-mixed with the activated sludge again.

[0075] Comparative Example 4:

[0076] The sludge was the same as in Example 4, Step, and was activated sludge without magnetic powder as a blank and activated sludge loaded with 500 mg / L of recovered hard magnetic Fe3O4 magnetic powder. The COD removal rate is shown in Table 5.

[0077] Table 5

[0078]

[0079] Example 5:

[0080] (1) 1 L of activated sludge containing 500 mg / L of pre-magnetized soft magnetic powder (FeSiAl) was placed in an aeration tank.

[0081] (2) The actual printing and dyeing wastewater was used as the object, the water volume and the sludge volume were kept at 1:1, the SBR process was used, the reaction device was operated in the process of water inlet-aeration-settling-drainage, the aeration time was 12 h, and the settling time was 1 h. In the aeration stage, disc aeration was used, the DO was maintained at 1-3 mg / L, and mechanical stirring was used as the flow action.

[0082] (3) After the operation cycle was completed, the supernatant was sampled, and the potassium dichromate method (HJ828-2017) and alkaline potassium persulfate digestion ultraviolet spectrophotometry (HJ 636-2012) were used for analysis.

[0083] (4) The magnetic powder was recovered when the sludge was discharged, and was re-premixed with the activated sludge.

[0084] Comparative Example 5:

[0085] The amount of magnetic powder used in this example was 700 mg / L, which was used as a comparison, as shown in Table 6.

[0086] Table 6

[0087]

[0088]

[0089] Example 6:

[0090] (1) 1 L of activated sludge containing 500 mg / L of pre-magnetized soft magnetic powder (FeSiAl) was placed in an aeration tank.

[0091] (2) The simulated wastewater was used as the object, the water volume and the sludge volume were kept at 1:1, the SBR process was used, the reaction device was operated in the process of water inlet-aeration-settling-drainage, the aeration time was 12 h, and the settling time was 1 h. In the aeration stage, disc aeration was used, the DO was maintained at 1-3 mg / L, and mechanical stirring was used as the flow action.

[0092] (3) After the end of the running cycle, the supernatant of the effluent was sampled, and the analysis method was potassium dichromate method (HJ828-2017) and alkaline potassium persulfate digestion UV spectrophotometry (HJ 636-2012).

[0093] (4) The magnetic powder was recovered during sludge discharge and pre-mixed with the activated sludge again.

[0094] Comparative Example 6:

[0095] The same as the step of Example 6, the amount of magnetic powder put into this example was 700 mg / L, and it was used as a comparison, as shown in Table 7.

[0096] Table 7

[0097]

Claims

1. A soft-magnetic magnetically-loaded activated sludge sewage treatment method, characterized by, The application relates to a method for treating wastewater by using magnetic activated sludge. The method comprises the following steps: Step 1, pre-mixing active sludge and pre-magnetized soft magnetic powder; the soft magnetic powder is FeSiAl; Step 2, treating wastewater by using the SBR process of the pre-mixed magnetic activated sludge; Step 3, sampling the supernatant to measure biochemical indexes at the end of a running period; 2. The soft magnetic magnetically loaded activated sludge sewage treatment method as claimed in claim 1, wherein, Step 4, recycling the magnetic powder by using a strong magnetic field during the sludge discharge process at the end of each running period, and re-adding the magnetic powder into the active sludge for pre-mixing in step 1.

3. The soft magnetic magnetically loaded activated sludge sewage treatment method as claimed in claim 1, wherein, In step 1, the pre-magnetization condition is a magnetic field of 2000-3000 GS, and the pre-magnetization time is 5-10 min.

4. The soft magnetic magnetically loaded activated sludge sewage treatment method as claimed in claim 1, wherein, In step 1, 500-700 mg / L of the pre-magnetized soft magnetic powder is added into 1 L of the active sludge in batches.

5. The soft magnetic magnetically loaded activated sludge sewage treatment method as claimed in claim 1, wherein, In step 2, the reaction device adopts the process of water feeding, aeration, precipitation and water discharge; the aeration time is 8-12 h, and the precipitation time is 1-2 h; the disc type aeration is adopted in the aeration stage, the DO is maintained at 1-3 mg / L, and mechanical stirring is used for the plug flow; the speed of the mechanical stirring is 150-180 r / min, and the aeration flow is kept at 0.1-0.3 L / min.

6. The soft magnetic magnetically loaded activated sludge sewage treatment method as claimed in claim 1, wherein, In step 2, the volume ratio of the water to the sludge is kept at 1:1.5-1:

1.

7. The soft magnetic magnetically supported activated sludge sewage treatment method as claimed in claim 1, wherein, In step 2, the pH of the wastewater is kept at 7-8.5 during the whole running period.

8. The soft magnetic magnetically supported activated sludge sewage treatment method as claimed in claim 1, wherein, In step 3, the biochemical indexes are the chemical oxygen demand and the TN concentration. In step 4, the magnetic field strength for recycling the magnetic powder is 2000-3000 GS.

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