Method for recovering fungal bulking halophilic aerobic granular sludge by using iron ions

Abstract

The application discloses a method for recovering fungal expanded salt-tolerant aerobic granular sludge by using iron ions, and belongs to the field of wastewater biological treatment. The principle of the application is that by adding iron ions, different biological effects caused by the iron ions on bacteria and fungi are utilized, the proliferation of bacteria is promoted, and the proliferation of fungi is inhibited, so that the number of fungi is reduced, and the recovery of the compact and stable structure of the fungal expanded salt-tolerant aerobic granular sludge is realized. The application can make the salt-tolerant aerobic granular sludge with excessive fungal growth recover the compact and dense granules in a short time, and ensure the stable operation of the system and the rapid treatment of high-salinity wastewater. The method utilizes the iron ion concentration which does not cause ecological risks or environmental pollution to the sludge treatment system, and has the advantages of low cost, simple operation, safety, high efficiency, stability and reliability.

Description

Technical Field

[0001] This invention belongs to the field of biological wastewater treatment, specifically a method for restoring fungal bulking halophilic aerobic granular sludge using iron ions. Background Technology

[0002] With industrial development, the generation of high-salinity wastewater is constantly increasing. Since freshwater microorganisms cannot survive under high-salinity conditions, halophilic aerobic granular sludge, cultivated using halophilic microorganisms, has demonstrated excellent pollutant degradation capabilities in high-salinity wastewater treatment. During the formation of halophilic aerobic granular sludge, fungi can act as granular nuclei, increasing the colonization area of ​​bacteria. However, changes in environmental conditions and operating parameters can easily lead to fungal bulking, causing granular sludge disintegration, resulting in significant sludge loss and effluent deterioration. This limits the widespread application of halophilic aerobic granular sludge.

[0003] Researchers have proposed several solutions for restoring granular sludge. Patent CN201810013867.9 effectively controls sludge bulking and forms smooth, rounded granular sludge by changing reactor operating conditions, increasing aeration intensity, and gradually shortening settling time. Patent CN201210158479.2 increases the influent chemical oxygen demand (COD) to 1000–1500 mg / L, giving flocculent bacteria, which are beneficial for granular stability, a competitive advantage over filamentous bacteria. The high hydraulic shear force provided by high aeration (4–7 L / min) then causes filamentous bacteria to detach from the surface of the granular sludge and be discharged from the system, restoring the compact structure of the granular sludge. Patent CN201910301631.X introduces quorum sensing signal molecules to promote the secretion of more extracellular polymers by microorganisms, increasing the density and hydrophobicity of the granular sludge and restoring its structural integrity. However, these technologies are all based on freshwater granular sludge, and research on restoration technologies based on halophilic granular sludge is limited. Patent CN202211223203.8 utilizes the different biomagnetic effects of magnetic fields on bacteria and fungi, effectively inhibiting the proliferation of filamentous fungi by applying an external magnetic field, thus achieving the restoration of fungal-bulking halophilic granular sludge. However, due to high cost, high energy consumption, and space limitations, the application scenarios of external magnetic fields are relatively limited. There is an urgent need to develop more efficient and energy-saving halophilic aerobic granular sludge restoration strategies to ensure the stable operation of halophilic aerobic granular sludge systems.

[0004] To address the above problems, this invention proposes a method for restoring fungal bulking halophilic aerobic granular sludge using iron ions. By adding iron ions, the proliferation of fungi is effectively inhibited, the number of fungi is reduced, and the compact and stable structure of the halophilic aerobic granular sludge is restored. Summary of the Invention

[0005] The purpose of this invention is to restore fungal-bloated halophilic aerobic granular sludge and ensure its long-term stable operation in practical applications.

[0006] This invention proposes a method for restoring fungal bulking halophilic aerobic granular sludge using iron ions. The method is characterized by adding iron ions to the halophilic aerobic granular sludge that has undergone fungal bulking. The inhibitory effect of iron ions on fungal proliferation reduces the number of fungi, thereby restoring the compact and stable structure of the halophilic aerobic granular sludge. The implemented apparatus is as follows: Figure 1 As shown, the device includes: (1) a water tank and (2) a booster pump. The processing flow of the device is as follows: the iron ion concentrated mother liquor in the water tank (1) is fed into the inlet of the sewage treatment aeration tank by the booster pump (2).

[0007] Based on the above-mentioned device, the steps for restoring iron ions in fungal bulking halophilic aerobic granular sludge include:

[0008] Step 1: Prepare a concentrated mother liquor with an iron ion concentration of 50-100 g / L using iron salts and store it in a water tank (1).

[0009] Step 2: Turn on the booster pump (2) to introduce the mother liquor from the water tank (1) into the inlet of the halophilic aerobic granular sludge aeration tank where fungal bulking has occurred. The formula for calculating the booster pump flow rate is as follows: Where C1 is the iron ion concentration in the aeration tank (5-10 mg / L), C0 is the mother liquor concentration, Q is the design water volume of the aeration tank, and HRT is the hydraulic retention time of the aeration tank.

[0010] Step 3: Run continuously for 20-30 days, observing the sludge surface until no visible mycelia are visible. The sludge sets well, and the fungal-blown halophilic aerobic granular sludge recovers its compact structure.

[0011] Step 4: Stop introducing iron ions.

[0012] Step 5: If mycelia are still present on the sludge surface, repeat steps 1 and 2 for 20 to 30 days until no mycelia are visible on the sludge surface.

[0013] The iron salts mentioned in step 1 include ferric chloride, ferric sulfate, and ferric nitrate.

[0014] Technical principle of the invention:

[0015] This invention utilizes the difference in the effects of iron ions on the proliferation of fungi and bacteria to restore the compact and stable structure of halophilic aerobic granular sludge. The principle and effect diagram are shown below. Figure 2Iron ions can affect the metabolic level and cell activity of microorganisms, causing different biological effects on bacteria and fungi. For bacteria, iron ions at a concentration of 5–10 mg / L can act as a cofactor for enzymes, promoting the synthesis of bacterial iron-sulfur proteins and hemoglobin. For fungi, iron ions at a concentration of 5–10 mg / L will coat and cover fungal hyphae, inhibiting the fungi's utilization of nutrients and having a toxic effect on fungal hyphae. Therefore, under the same concentration of iron ions, bacterial proliferation is promoted, while fungal proliferation is inhibited, thereby reducing the number of fungi. This method can restore the compact and stable structure of fungal bulking halophilic aerobic granular sludge.

[0016] The beneficial effects of this invention are:

[0017] Through the above methods, under the action of iron ions, the growth of fungi can be inhibited, and the compact and stable structure of fungal bulking halophilic aerobic granular sludge can be restored.

[0018] Iron salts are commonly used flocculants in wastewater treatment plants. Iron ions at concentrations of 5–10 mg / L do not pose an ecological risk or environmental pollution to sludge treatment systems. This method is low-cost, simple to operate, safe, efficient, stable, and reliable, making it an effective and widely applicable method for restoring fungal bulking halophilic aerobic granular sludge. Attached Figure Description

[0019] Figure 1 Here is a schematic diagram of the device structure used in this invention: (1) water tank, (2) lift pump.

[0020] Figure 2 This is a rendering of the invention. Detailed Implementation

[0021] The present invention will be further described in detail with reference to the accompanying drawings and embodiments, but the present invention is not limited to the following embodiments.

[0022] The effects of Examples 1-6 are very similar, and all can be used Figure 2 express.

[0023] Example 1: Restoration of fungal bulking in halophilic aerobic granular sludge using 5 mg / L iron ions

[0024] Step 1: Prepare a concentrated mother liquor with an iron ion concentration of 50 g / L using ferric chloride and store it in a water tank (1).

[0025] Step 2: Turn on the booster pump (2) and introduce the mother liquor in the water tank (1) into the inlet of the halophilic aerobic granular sludge aeration tank where fungal swelling has occurred, so that the iron ion concentration in the aeration tank is maintained at 5 mg / L.

[0026] Step 3: Run continuously for 20 days, observing the sludge surface until no visible mycelia are visible. The sludge sets well, and the fungal-bloated halophilic aerobic granular sludge recovers its compact structure.

[0027] Step 4: Stop introducing iron ions.

[0028] After 20 days of continuous operation with 5 mg / L iron ions, the number of bacteria increased significantly, while the number of fungi decreased significantly. The recovered halophilic aerobic granular sludge had a compact and dense structure, and the system operated stably.

[0029] Example 2: Restoration of fungal bulking in halophilic aerobic granular sludge using 6 mg / L iron ions

[0030] Step 1: Prepare a concentrated mother liquor with an iron ion concentration of 60 g / L using ferric chloride and store it in a water tank (1).

[0031] Step 2: Turn on the booster pump (2) and introduce the mother liquor in the water tank (1) into the inlet of the halophilic aerobic granular sludge aeration tank where fungal swelling has occurred, so that the iron ion concentration in the aeration tank is maintained at 6 mg / L.

[0032] Step 3: Run continuously for 20 days, observing the sludge surface until no visible mycelia are visible. The sludge sets well, and the fungal-bloated halophilic aerobic granular sludge recovers its compact structure.

[0033] Step 4: Stop introducing iron ions.

[0034] After 20 days of continuous operation with 6 mg / L iron ions, the number of bacteria increased significantly, while the number of fungi decreased significantly. The recovered halophilic aerobic granular sludge had a compact and dense structure, and the system operated stably.

[0035] Example 3: Restoration of fungal bulking in halophilic aerobic granular sludge using 7 mg / L iron ions

[0036] Step 1: Prepare a concentrated mother liquor with an iron ion concentration of 70 g / L using ferric chloride and store it in a water tank (1).

[0037] Step 2: Turn on the booster pump (2) and introduce the mother liquor in the water tank (1) into the inlet of the halophilic aerobic granular sludge aeration tank where fungal expansion has occurred, so that the iron ion concentration in the aeration tank is maintained at 7 mg / L.

[0038] Step 3: Run continuously for 20 days, observing the sludge surface until no visible mycelia are visible. The sludge sets well, and the fungal-bloated halophilic aerobic granular sludge recovers its compact structure.

[0039] Step 4: Stop introducing iron ions.

[0040] After 20 days of continuous operation with 7 mg / L iron ions, the number of bacteria increased significantly, while the number of fungi decreased significantly. The recovered halophilic aerobic granular sludge had a compact and dense structure, and the system operated stably.

[0041] Example 4: Restoration of fungal bulking in halophilic aerobic granular sludge using 8 mg / L iron ions

[0042] Step 1: Prepare a concentrated mother liquor with an iron ion concentration of 80 g / L using ferric chloride and store it in a water tank (1).

[0043] Step 2: Turn on the booster pump (2) and introduce the mother liquor in the water tank (1) into the inlet of the halophilic aerobic granular sludge aeration tank where fungal swelling has occurred, so that the iron ion concentration in the aeration tank is maintained at 8 mg / L.

[0044] Step 3: Run continuously for 20 days, observing the sludge surface until no visible mycelia are visible. The sludge sets well, and the fungal-bloated halophilic aerobic granular sludge recovers its compact structure.

[0045] Step 4: Stop introducing iron ions.

[0046] After 20 days of continuous operation with 8 mg / L iron ions, the number of bacteria increased significantly, while the number of fungi decreased significantly. The recovered halophilic aerobic granular sludge had a compact and dense structure, and the system operated stably.

[0047] Example 5: Restoration of fungal bulking in halophilic aerobic granular sludge using 9 mg / L iron ions

[0048] Step 1: Prepare a concentrated mother liquor with an iron ion concentration of 90 g / L using ferric chloride and store it in a water tank (1).

[0049] Step 2: Turn on the booster pump (2) and introduce the mother liquor in the water tank (1) into the inlet of the halophilic aerobic granular sludge aeration tank where fungal swelling has occurred, so that the iron ion concentration in the aeration tank is maintained at 9 mg / L.

[0050] Step 3: Run continuously for 20 days, observing the sludge surface until no visible mycelia are visible. The sludge sets well, and the fungal-bloated halophilic aerobic granular sludge recovers its compact structure.

[0051] Step 4: Stop introducing iron ions.

[0052] After 20 days of continuous operation with 9 mg / L iron ions, the number of bacteria increased significantly, while the number of fungi decreased significantly. The recovered halophilic aerobic granular sludge had a compact and dense structure, and the system operated stably.

[0053] Example 6: Restoration of fungal bulking in halophilic aerobic granular sludge using 10 mg / L iron ions

[0054] Step 1: Prepare a concentrated mother liquor with an iron ion concentration of 100 g / L using ferric chloride and store it in a water tank (1).

[0055] Step 2: Turn on the booster pump (2) and introduce the mother liquor in the water tank (1) into the inlet of the halophilic aerobic granular sludge aeration tank where fungal swelling has occurred, so that the iron ion concentration in the aeration tank is maintained at 10 mg / L.

[0056] Step 3: Run continuously for 20 days, observing the sludge surface until no visible mycelia are visible. The sludge sets well, and the fungal-bloated halophilic aerobic granular sludge recovers its compact structure.

[0057] Step 4: Stop introducing iron ions.

[0058] After 20 days of continuous operation with 10 mg / L iron ions, the number of bacteria increased significantly, while the number of fungi decreased significantly. The recovered halophilic aerobic granular sludge had a compact and dense structure, and the system operated stably.

Claims

1. A method for restoring fungal bulking halophilic aerobic granular sludge using iron ions, characterized by the following steps: include: Step 1: Prepare a concentrated mother liquor with an iron ion concentration of 50-100 g / L using iron salts and store it in a water tank (1); Step 2: Turn on the booster pump (2) to introduce the mother liquor from the water tank (1) into the inlet of the halophilic aerobic granular sludge aeration tank where fungal bulking has occurred; the formula for calculating the flow rate of the booster pump is as follows: C0 is the concentration of mother liquor, Q is the design water volume of the aeration tank, and HRT is the hydraulic retention time of the aeration tank; Step 2 is used to ensure that the iron ion concentration in C1, i.e., the aeration tank, is 5-10 mg / L. Step 3: Run continuously for 20-30 days, observe the sludge surface until no mycelium is visible to the naked eye on the sludge surface; Step 4: Stop introducing iron ions.

2. The method according to claim 1, characterized in that: The iron salt mentioned in step 1 is ferric chloride, ferric sulfate, or ferric nitrate.

3. The method according to claim 1, characterized in that: Step 5: If mycelia are still present on the sludge surface, repeat steps 1 and 2 for 20-30 days until no mycelia are visible to the naked eye on the sludge surface.

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