Method for conditioning and strengthening aerobic granular sludge dewatering by mechanical crushing coupled with persulfate

Abstract

The application discloses a method for dewatering of aerobic granular sludge by mechanical crushing and coupling of persulfate conditioning and strengthening. The method is based on chemical conditioning, combined with filter cloth filtration and mechanical crushing, and effectively improves the dewatering capacity of the aerobic granular sludge, and is a practical and feasible dewatering method for the aerobic granular sludge, and has a promotion and application prospect.

Description

Technical Field

[0001] This invention belongs to the field of sludge treatment technology, specifically relating to a method for dewatering aerobic granular sludge by mechanical crushing coupled with persulfate conditioning. Background Technology

[0002] Sludge dewatering is a necessary step in the treatment of excess sludge in activated sludge processes. Traditional activated sludge processes produce excess sludge with high moisture content, large volume, and poor dewatering properties, significantly increasing transportation and disposal costs. Currently, sludge management costs account for 30-60% of the total operating costs of wastewater treatment plants. Sludge dewatering has been proven to be an effective measure to reduce sludge moisture content; therefore, reducing the moisture content of excess sludge is crucial for sludge reduction and lowering wastewater treatment plant operating costs.

[0003] Aerobic granular sludge is an emerging wastewater biological treatment technology, essentially a special biofilm formed by the self-aggregation of activated sludge microorganisms. Since its first report in 1997, aerobic granular sludge has been widely researched and applied in municipal wastewater treatment, industrial wastewater treatment, and high-value-added product recovery. Currently, with the large-scale engineering applications of aerobic granular sludge technology, the treatment and disposal of excess aerobic granular sludge has received wider attention and emphasis, making the efficient dewatering of aerobic granular sludge an urgent priority.

[0004] Aerobic granular sludge possesses a complete and dense spatial structure and a high extracellular polymer content, giving it dewatering characteristics completely different from traditional flocculent activated sludge. Aerobic granular sludge exhibits excellent settling performance and a lower surface charge, indicating that surface free water is more easily removed, while internal water is more tightly bound to the granular structure by the extracellular polymers, making it relatively difficult to remove. Simultaneously, the dense structure of aerobic granular sludge makes traditional sludge conditioning methods inefficient, failing to release large amounts of internal bound water. This characteristic also severely hinders the dewatering efficiency of excess aerobic granular sludge. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method for enhancing the dewatering of aerobic granular sludge through mechanical crushing coupled with persulfate conditioning. This invention, targeting the different structural characteristics and extracellular polymer content of aerobic granular sludge compared to traditional flocculent activated sludge, combines chemical conditioning with physical methods of filter cloth filtration and mechanical crushing. This effectively improves the dewatering capacity of aerobic granular sludge, representing a practical and feasible dewatering method with promising prospects for widespread application.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for enhancing aerobic granular sludge dewatering by mechanical crushing coupled with persulfate conditioning includes the following steps:

[0008] S1. The remaining aerobic granular sludge is quickly filtered through a filter cloth to remove most of the free water, resulting in concentrated aerobic granular sludge.

[0009] S2. The submersible pump is placed into the concentrated aerobic granular sludge for mechanical crushing to obtain crushed aerobic granular sludge.

[0010] S3. Add persulfate to the crushed aerobic granular sludge, stir for a period of time, then add ferrous chloride solution, stir for a period of time again, and the conditioning of the crushed aerobic granular sludge is completed.

[0011] S4. The conditioned sludge is centrifuged and dewatered to complete the dewatering of aerobic granular sludge.

[0012] Preferably, the concentration of residual aerobic granular sludge in S1 is 6-15 g / L.

[0013] Preferably, the filter cloth in S1 is a polyester filter cloth with a pore size of 0.18-0.43 mm (35-80 mesh).

[0014] Preferably, the concentration of the concentrated aerobic granular sludge obtained in step S1 is 30-60 g / L, and the moisture content is 91-96%.

[0015] Preferably, the submersible pump used in S2 has a power of 100-2200W, a crushing time of 30-60min, and the average particle size of the resulting crushed aerobic granular sludge is 0.1-0.5mm.

[0016] Preferably, the persulfate in S3 is sodium persulfate or potassium persulfate.

[0017] Preferably, the dosage of persulfate in S3 is 50.0-200.0 mg / g dry sludge, and the dosage of ferrous chloride solution is 15-30 mg FeCl2 / g dry sludge.

[0018] Preferably, the stirring time for adding persulfate and ferrous chloride in S3 is 10-30 min, and the stirring speed is 100-300 r / min.

[0019] Preferably, the centrifugal dehydration speed in S4 is 2000-4000 r / min, and the centrifugation time is 5-10 min.

[0020] Preferably, the sludge after dewatering treatment S1-S4 has a moisture content of 80%-83%.

[0021] The beneficial effects of this invention are as follows:

[0022] This invention utilizes filter cloth filtration to rapidly remove most of the free water from aerobic granular sludge. The free water in aerobic granular sludge is more easily removed than in traditional flocculent activated sludge. Therefore, filter cloth can simply and efficiently remove most of the free water, reducing the sludge's moisture content and laying a good foundation for subsequent treatment.

[0023] This invention utilizes a submersible pump for efficient mechanical crushing of aerobic granular sludge. While disrupting the microbial cell structure, it breaks down the spatial structure of the particles, releasing a small amount of tightly bound extracellular polymers, transforming them into loose and dissolved extracellular polymers. This process facilitates the removal of some of the released internal bound water and a large amount of free water, while also benefiting subsequent sludge conditioning and further improving dewatering efficiency.

[0024] This invention employs an advanced oxidation method using persulfate to condition crushed aerobic granular sludge. Persulfate, through the breakdown of extracellular polymers and organic matter in the sludge via persulfate ions, releases a large amount of interstitial water and bound water, thereby improving dewatering efficiency. Simultaneously, persulfate ions have a relatively long lifespan, enabling them to oxidize organic components in the sludge under a wider pH range. Furthermore, this invention also utilizes Fe... 2+ As a catalyst, it further activates the free radicals in the reaction, and the Fe formed after the oxidation reaction is completed... 3+ It can also further undergo coagulation. The mechanically crushed aerobic granular sludge makes it easier for active free radicals such as persulfate to come into contact with the sludge, improving the release efficiency of extracellular polymers and thus enhancing the conditioning effect of persulfate. Attached Figure Description

[0025] Figure 1 The two samples are aerobic granular sludge (A) that has not undergone the dewatering treatment of this invention and aerobic granular sludge (B) that has undergone the dewatering treatment of this invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0027] Example 1

[0028] Take the remaining aerobic granular sludge to be treated, such as Figure 1As shown in (A), the sludge concentration was 8 g / L, the average particle size was 854 μm, and the moisture content was 96.3%. The remaining aerobic granular sludge was loaded into an 80-mesh polyester filter cloth, and most of the free water was removed by gravity compression and extrusion to obtain concentrated aerobic granular sludge with a concentration of 30 g / L and a moisture content of 94%. A 100W submersible pump was placed in the concentrated aerobic granular sludge for mechanical crushing for 60 min to obtain crushed aerobic granular sludge with an average particle size of 325 μm. 50.0 mg / g of dry sludge sodium persulfate was added to the mechanically crushed aerobic granular sludge, and the mixture was stirred at 180 r / min for 10 min. Then, 15 mg / g of FeCl2 / g of dry sludge ferrous chloride solution was added, and the mixture was stirred at 150 r / min for 15 min to complete the sludge dewatering and conditioning process. The prepared aerobic granular sludge was placed in a centrifugal dewatering machine for centrifugal dewatering at a speed of 2000 r / min for 5 min. Figure 1 (B) shows the morphology of the aerobic granular sludge after dewatering treatment. It can be seen that the particle size of the aerobic granular sludge significantly decreased after dewatering treatment according to the present invention. In addition, after mechanical crushing coupled with persulfate conditioning and centrifugal dewatering, the moisture content of the sludge cake decreased to 82.9%, which is 6% lower than that of the aerobic granular sludge without mechanical crushing and persulfate conditioning. Moreover, the indicators characterizing the sludge dewatering efficiency, such as sludge specific resistance and capillary water absorption time, were not affected.

[0029] Example 2

[0030] The remaining aerobic granular sludge to be treated had a concentration of 15 g / L, an average particle size of 623 μm, and a moisture content of 95.2%. This remaining aerobic granular sludge was loaded into a 35-mesh polyester filter cloth, and most of the free water was removed by gravity compression and extrusion to obtain concentrated aerobic granular sludge with a concentration of 60 g / L and a moisture content of 92%. A 2200 W submersible pump was placed in the concentrated aerobic granular sludge for mechanical crushing for 30 minutes to obtain crushed aerobic granular sludge with an average particle size of 108 μm. 200.0 mg / g of dry sludge sodium persulfate was added to the mechanically crushed aerobic granular sludge, and the mixture was stirred at 180 rpm for 30 minutes. Then, 30 mg / g of dry sludge ferrous chloride solution was added, and the mixture was stirred at 150 rpm for 30 minutes to complete the sludge dewatering and conditioning process. The prepared aerobic granular sludge was placed in a centrifuge for centrifugal dewatering at 4000 rpm for 10 minutes. After mechanical crushing coupled with persulfate conditioning and centrifugation, the moisture content of the sludge cake decreased to 82.3%, which was 6% lower than that of the aerobic granular sludge without mechanical crushing and persulfate conditioning. Furthermore, indicators of sludge dewatering efficiency, such as sludge specific resistance and capillary suction time, were not affected.

[0031] Example 3

[0032] The remaining aerobic granular sludge to be treated had a concentration of 10 g / L, an average particle size of 810 μm, and a moisture content of 93.8%. This remaining aerobic granular sludge was loaded into a 60-mesh polyester filter cloth, and most of the free water was removed by gravity compression and extrusion to obtain concentrated aerobic granular sludge with a concentration of 35 g / L and a moisture content of 92%. A 1000 W submersible pump was placed in the concentrated aerobic granular sludge for mechanical crushing for 60 min, resulting in crushed aerobic granular sludge with an average particle size of 210 μm. Sodium persulfate (100.0 mg / g dry sludge) was added to the mechanically crushed aerobic granular sludge, and the mixture was stirred at 180 r / min for 15 min. Then, ferrous chloride solution (23.5 mg FeCl2 / g dry sludge) was added, and the mixture was stirred at 150 r / min for 10 min to complete the sludge dewatering and conditioning process. The prepared aerobic granular sludge was placed in a centrifuge for centrifugal dewatering at 4000 rpm for 10 minutes. After mechanical crushing coupled with persulfate conditioning and centrifugation, the moisture content of the sludge cake decreased to 80.0%, which is 8% lower than that of the aerobic granular sludge without mechanical crushing and persulfate conditioning. Moreover, the indicators characterizing the sludge dewatering efficiency, such as sludge specific resistance and capillary water absorption time, were not affected.

[0033] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for conditioning and enhancing dewatering of an aerobic granular sludge by mechanical breakage coupled with persulfate, characterized in that, The method comprises the following steps: S1. Rapidly filter the residual aerobic granular sludge through filter cloth to remove most of the free water, to obtain concentrated aerobic granular sludge; S2. Put a submersible pump into the concentrated aerobic granular sludge to mechanically break it, to obtain broken aerobic granular sludge; S3. Add persulfate to the broken aerobic granular sludge, stir for a period of time, then add ferrous chloride solution, and stir for a period of time, to complete conditioning of the broken aerobic granular sludge; S4. Centrifugal dewater the conditioned sludge, to complete dewatering of the aerobic granular sludge; The moisture content of the sludge after dewatering treatment of S1-S4 is 80%-83%.

2. The method of claim 1, wherein, The concentration of the residual aerobic granular sludge in S1 is 6-15 g / L.

3. The method of claim 1, wherein, The filter cloth in S1 is polyester filter cloth, and the pore size is 35-80 mesh.

4. The method of claim 1, wherein, The concentration of the concentrated aerobic granular sludge obtained in S1 is 30-60 g / L, and the moisture content is 91-96%.

5. The method of claim 1, wherein, The power of the submersible pump used in S2 is 100-2200 W, the breaking time is 30-60 min, and the average particle size of the obtained broken aerobic granular sludge is 0.1-0.5 mm.

6. The method of claim 1, wherein, The persulfate in S3 is sodium persulfate or potassium persulfate.

7. The method of claim 1, wherein, The dosage of the persulfate in S3 is 50.0-200.0 mg / g of dry sludge, and the dosage of the ferrous chloride solution is 15-30 mg of FeCl2 / g of dry sludge.

8. The method of claim 1, wherein, The stirring time for adding the persulfate and the ferrous chloride in S3 is both 10-30 min, and the stirring speed is both 100-300 r / min.

9. The method of claim 1, wherein, The centrifugal dewatering speed in S4 is 2000-4000 r / min, and the centrifugal time is 5-10 min.

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