A method for extracting soluble organic matter from sludge

Abstract

The application discloses a kind of extraction methods of soluble organic matter in sludge, first to sludge micropore activation treatment, then using focused ultrasonic wave, cooperate hydraulic pulse alternation, obtain pretreatment sludge;In 5 ℃ low temperature environment, continuously into ozone to pretreatment sludge, then sequentially through ceramic microfiltration membrane and organic nanofiltration membrane are separated, again to the separated liquid pulse voltage treatment, then through concentration, evaporation and nitrogen cyclone drying system to concentrated separated liquid are handled, obtain the DOM powdery product with water content≤3%.The present application can promote specific dissociation organic matter-colloid complex by using micropore activation treatment, acoustic pressure pulse breaking treatment and the like, without the intervention of chemical additives, without secondary pollution risk and other problems.

Description

Technical Field

[0001] This invention relates to the field of sludge treatment technology, specifically to a method for extracting soluble organic matter from sludge. Background Technology

[0002] Sludge is a byproduct of wastewater treatment, an extremely complex heterogeneous substance composed of organic debris, bacterial cells, inorganic particles, colloids, and other components. The main characteristics of sludge are high water content (up to 99% or more), high organic matter content, easy putrefaction and foul odor, fine particles, low specific gravity, and a colloidal liquid state. It is a viscous substance between liquid and solid, which can be pumped, but it is difficult to separate into solid and liquid phases through sedimentation.

[0003] Extraction technology of soluble organic matter from sewage sludge is an important research direction in the field of waste resource utilization. With the acceleration of urbanization, sewage sludge production is increasing year by year, and the large amount of organic matter it contains (such as proteins, polysaccharides, and humic acids) has potential resource value. Traditional sewage sludge treatment aims at volume reduction and harmlessness, but direct incineration or landfill of organic matter easily leads to resource waste and environmental pollution. How to efficiently extract soluble organic matter and achieve resource conversion has become a core issue in current technological development.

[0004] In traditional methods, physicochemical treatment alters the sludge structure by adding alkaline solutions or chemical agents to dissolve organic matter, followed by sedimentation and separation to obtain the target substance. However, this approach suffers from drawbacks such as high agent consumption and a high risk of secondary pollution. Biochemical treatment relies on microbial metabolism to decompose organic matter. While this method is less expensive, the purity and efficiency of the extracted products are limited by microbial activity and the reaction cycle. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for extracting soluble organic matter from sludge.

[0006] The technical solution of this invention is: a method for extracting soluble organic matter from sludge, comprising the following steps:

[0007] S1. The sludge undergoes microporous activation treatment, followed by incubation in a constant temperature bath at 18–25℃ using a frequency of 1.0–1.5 MHz and a sound intensity of 0.5–1 W / cm². 2 Focused ultrasound, combined with 3-6 MPa hydraulic pulses (pulse width 50 μs) alternating for 40-50 min, yields pretreated sludge; specifically dissociates organic matter-colloidal complexes; disrupts cell wall structure and releases intracellular organic matter;

[0008] S2. In a low-temperature environment of 5℃, ozone is continuously introduced into the pretreated sludge for a contact time of 15-25 minutes to promote the dissolution of organic matter. Then, the sludge is separated by passing it through a ceramic microfiltration membrane and an organic nanofiltration membrane in sequence to obtain a separated liquid. The separation is carried out in two stages, with gradient membrane separation to achieve the fractional collection of macromolecular humic acid and small molecule DOM.

[0009] S3. Apply pulse voltage to the separated liquid for 35-45 minutes to increase the DOM concentration to 1500 mg / L; then maintain the temperature of the concentration device at 4℃ and concentrate the separated liquid to 1 / 5 of the original volume by vacuum evaporation (vacuum degree -0.08 MPa) to obtain concentrated separated liquid.

[0010] S4. The concentrated separation liquid is treated with a -30℃ nitrogen cyclone drying system to instantly solidify the organic active ingredients and obtain DOM powder product with a water content of ≤3%.

[0011] Furthermore, the micropore activation treatment method is as follows: sludge with a moisture content of 80-90% is placed in a subcritical carbon dioxide environment, and the pressure is maintained at 8MPa for 25-40 minutes.

[0012] Note: Subcritical CO2 has high solubility and diffusivity, which can effectively extract fat-soluble organic matter or target substances from sludge and improve treatment efficiency. By treating in a subcritical carbon dioxide environment, the diffusion channels of organic matter can be expanded to activate the micropores of sludge and improve the extraction rate of DOM in subsequent sludge extraction.

[0013] Furthermore, after being kept in the subcritical carbon dioxide environment for 10 to 15 minutes, the sludge is treated with a pulsed DC electric field for 90 to 150 minutes. The field strength of the pulsed DC electric field is 12 to 15 V / cm, the pulse width is 1 ms, and the interval is 3 to 5 ms, which promotes the migration and aggregation of negatively charged dissolved organic matter towards the positive electrode.

[0014] Explanation: By utilizing the directional alignment characteristics of electric fields, a pulsed DC electric field is used to treat the sludge after microporous activation. Under the electrophoretic enrichment effect, negatively charged dissolved organic matter is promoted to migrate and aggregate towards the positive electrode, thereby enhancing the subsequent extraction effect of DOM in the sludge.

[0015] Furthermore, the alternation of the focused ultrasound and hydraulic pulse is as follows: each alternation cycle includes 10-12 seconds of focused ultrasound sound pressure breaking and 5-7 seconds of hydraulic pulse hydraulic impact.

[0016] Explanation: By using acoustic pressure pulse crushing to treat pretreated sludge, and employing a combination of focused ultrasound and hydraulic pulses, the organic matter-colloidal complex can be specifically dissociated under cavitation dissociation. The acoustic pressure crushing and hydraulic impact under the above-mentioned alternating cycle have the best effect on sludge crushing, thereby promoting the extraction rate of DOM in sludge during subsequent treatment.

[0017] Furthermore, during ozone introduction, ultrasonic synergistic treatment with a frequency of 40 kHz and a gradually decreasing power density was added. After the ultrasonic power density decreased to 0.1 W / mL, the ozone concentration was increased at an increase rate of 2–5 mg / L per minute.

[0018] The initial power density of the ultrasound is 0.5 W / mL, the attenuation rate is x W / mL, and the ultrasound co-processing time is t, satisfying the following formula:

[0019]

[0020] The constant i takes the value 1 or 2.

[0021] Explanation: In the early stages of ozone introduction, the use of ultrasound as a synergistic aid can promote the diffusion of ozone in the sludge. Ultrasound can also break ozone into microbubbles, significantly increasing the dissolution rate and expanding the reaction interface, thereby promoting the dissolution of organic matter. However, as ozone is continuously introduced, the synergistic effect of ultrasound gradually decreases. Furthermore, at this stage, the continuous use of high-power-density ultrasound can easily affect the dissolution of organic matter. Therefore, in the above operation, while utilizing ultrasound to synergize with ozone in the initial stage of treatment, the treatment effect of ozone on sludge can be significantly enhanced, and the dissolution of organic matter can be improved.

[0022] Furthermore, the pulse voltage is applied using a titanium-based ruthenium-iridium electrode, with a current density of 0.5–1 A / m. 2 The pulse voltage is 5V for 8-15 seconds in the positive direction and 3V for 3-8 seconds in the reverse direction.

[0023] Note: By using pulsed voltage to post-process the separated liquid, the DOM concentration can be further increased, thereby promoting the subsequent low-temperature concentration and low-temperature drying processes and obtaining high-quality DOM powder.

[0024] Furthermore, the operating pressure of the ceramic microfiltration membrane is 2.0 to 3.0 bar, and the operating pressure of the organic nanofiltration membrane is 8.0 to 10.0 bar.

[0025] Explanation: By employing a two-stage membrane filtration system for gradient membrane separation of sludge, it is possible to achieve the graded collection of macromolecular and small DOM molecules. Under the aforementioned operating pressure, ceramic microfiltration membranes and organic nanofiltration membranes can effectively perform filtration.

[0026] Furthermore, the gas velocity of the nitrogen cyclone drying system is 10–12 m / s, and the residence time is 12–15 s.

[0027] Note: The nitrogen cyclone drying system described above can instantly solidify the organic active ingredients, thereby obtaining a DOM powder product with a moisture content of ≤3%.

[0028] The beneficial effects of this invention are:

[0029] (1) The method for extracting soluble organic matter from sludge in this invention can promote the specific dissociation of organic matter-colloid complex by using micropore activation treatment and sound pressure pulse crushing treatment. There is no intervention of chemical additives, no risk of secondary pollution, and the organic matter recovery rate can reach 85-90%, which is 25-30% higher than the traditional method.

[0030] (2) The method for extracting soluble organic matter from sludge in this invention utilizes the synergistic treatment of ozone and ultrasound. This method can significantly enhance the treatment effect of ozone on sludge and improve the dissolution of organic matter while utilizing ultrasound in the initial stage of ozone treatment.

[0031] (3) The method for extracting soluble organic matter from sludge in this invention uses a two-stage membrane filtration process to perform gradient membrane separation of sludge, which enables the graded collection of macromolecules and small molecules of DOM, thereby providing more operational options for the extraction of soluble organic matter. Detailed Implementation

[0032] The present invention will now be described in more detail with reference to specific embodiments, so as to better demonstrate the advantages of the present invention.

[0033] Example 1: A method for extracting soluble organic matter from sludge, comprising the following steps:

[0034] S1. The sludge undergoes micropore activation treatment, wherein the micropore activation treatment method is as follows: sludge with a moisture content of 85% is placed in a subcritical carbon dioxide environment, and the pressure is maintained at 8 MPa for 35 minutes. Subsequently, it is placed in a constant temperature bath at 23°C, using a frequency of 1.2 MHz and a sound intensity of 0.8 W / cm². 2 Focused ultrasound, combined with 5MPa hydraulic pulses (pulse width 50μs), was applied alternately for 45 minutes. The alternation of focused ultrasound and hydraulic pulses was as follows: each alternation cycle included 11s of focused ultrasound acoustic pressure breaking and 6s of hydraulic pulse hydraulic impact to obtain pretreated sludge; specifically dissociated organic matter-colloidal complex; destroyed cell wall structure and released intracellular organic matter.

[0035] S2. Ozone is continuously introduced into the pretreated sludge at a low temperature of 5℃ for 20 minutes to promote the dissolution of organic matter. Subsequently, the sludge is separated by passing it through a ceramic microfiltration membrane and an organic nanofiltration membrane in sequence. The operating pressure of the ceramic microfiltration membrane is 2.5 bar, and the operating pressure of the organic nanofiltration membrane is 9.0 bar, resulting in a separated liquid. The separation is carried out in two stages, with gradient membrane separation to achieve the fractional collection of macromolecular humic acid and small molecule DOM.

[0036] S3. Apply a pulsed voltage to the separated liquid for 42 min using a titanium-based ruthenium-iridium electrode at a current density of 0.8 A / m. 2 The pulse voltage was applied for 12 seconds at a positive 5V and 5 seconds at a negative 3V, increasing the DOM concentration to 1500 mg / L. Subsequently, the temperature of the concentration device was maintained at 4℃, and the separated liquid was concentrated to 1 / 5 of its original volume by vacuum evaporation (vacuum degree -0.08MPa) to obtain the concentrated separated liquid.

[0037] S4. The concentrated and separated liquid is treated with a -30℃ nitrogen cyclone drying system. The gas velocity of the nitrogen cyclone drying system is 11m / s and the residence time is 14s. The organic active ingredients are instantly solidified to obtain DOM powder product with a water content of ≤3%.

[0038] Example 2: The difference between this example and Example 1 is that sludge with a moisture content of 80% is placed in a subcritical carbon dioxide environment and the pressure is maintained at 8 MPa for 25 minutes.

[0039] Example 3: The difference between this example and Example 1 is that sludge with a water content of 90% is placed in a subcritical carbon dioxide environment and the pressure is maintained at 8 MPa for 40 minutes.

[0040] Example 4: This example differs from Example 1 in that it uses a 18°C ​​constant temperature bath with a frequency of 1.0MHz and a sound intensity of 0.5W / cm². 2 The focused ultrasound, combined with 3MPa hydraulic pulses (pulse width 50μs), is applied alternately for 40 minutes. The alternation of the focused ultrasound and hydraulic pulses is as follows: each alternation cycle includes 10s of focused ultrasound sound pressure crushing and 5s of hydraulic pulse hydraulic impact to obtain pretreated sludge.

[0041] Example 5: This example differs from Example 1 in that it uses a frequency of 1.5MHz and a sound intensity of 1W / cm in a 25℃ constant temperature bath. 2 Focused ultrasound, combined with 6MPa hydraulic pulses (pulse width 50μs), is applied alternately for 50 minutes. The alternation of focused ultrasound and hydraulic pulse is as follows: each alternation cycle includes 12s of focused ultrasound sound pressure crushing and 7s of hydraulic pulse hydraulic impact to obtain pretreated sludge.

[0042] Example 6: This example differs from Example 1 in that ozone is continuously introduced into the pretreated sludge at a low temperature of 5°C for 15 minutes to promote the dissolution of organic matter; then, the sludge is separated by passing it through a ceramic microfiltration membrane and an organic nanofiltration membrane in sequence. The operating pressure of the ceramic microfiltration membrane is 2.0 bar, and the operating pressure of the organic nanofiltration membrane is 8.0 bar, resulting in a separated liquid.

[0043] Example 7: This example differs from Example 1 in that ozone is continuously introduced into the pretreated sludge at a low temperature of 5°C for 25 minutes to promote the dissolution of organic matter; then, the sludge is separated by passing it through a ceramic microfiltration membrane and an organic nanofiltration membrane in sequence. The operating pressure of the ceramic microfiltration membrane is 3.0 bar, and the operating pressure of the organic nanofiltration membrane is 10.0 bar, resulting in a separated liquid.

[0044] Example 8: This example differs from Example 1 in that a pulsed voltage was applied to the separated liquid for 35 minutes using a titanium-based ruthenium-iridium electrode, with a current density of 0.5 A / m. 2 The pulse voltage is 5V for 8 seconds in the positive direction and 3V for 3 seconds in the reverse direction.

[0045] Example 9: This example differs from Example 1 in that a pulsed voltage was applied to the separated liquid for 45 minutes using a titanium-based ruthenium-iridium electrode, with a current density of 1 A / m. 2 The pulse voltage is 5V for 15 seconds in the positive direction and 3V for 8 seconds in the reverse direction.

[0046] Example 10: The difference between this example and Example 1 is that a -30℃ nitrogen cyclone drying system is used to process the concentrated separation liquid. The gas velocity of the nitrogen cyclone drying system is 10m / s and the residence time is 12s.

[0047] Example 11: The difference between this example and Example 1 is that a -30℃ nitrogen cyclone drying system is used to process the concentrated separation liquid. The gas velocity of the nitrogen cyclone drying system is 12m / s and the residence time is 15s.

[0048] Example 12: This example differs from Example 1 in that, after being kept in the subcritical carbon dioxide environment for 12 minutes, a pulsed DC electric field is applied to the sludge for 135 minutes. The field strength of the pulsed DC electric field is 14 V / cm, the pulse width is 1 ms, and the interval is 4 ms, which causes the negatively charged dissolved organic matter to migrate and accumulate towards the positive electrode.

[0049] Example 13: The difference between this example and Example 12 is that after the subcritical carbon dioxide environment is maintained for 10 minutes, the sludge is treated with a pulsed DC electric field for 90 minutes. The field strength of the pulsed DC electric field is 12V / cm, the pulse width is 1ms, and the interval is 3ms, which promotes the migration and aggregation of negatively charged dissolved organic matter towards the positive electrode.

[0050] Example 14: The difference between this example and Example 12 is that after the subcritical carbon dioxide environment is maintained for 15 minutes, the sludge is treated with a pulsed DC electric field for 150 minutes. The field strength of the pulsed DC electric field is 15V / cm, the pulse width is 1ms, and the interval is 5ms, which causes the negatively charged dissolved organic matter to migrate and accumulate towards the positive electrode.

[0051] Example 15: This example differs from Example 12 in that, during ozone introduction, ultrasonic synergistic treatment with a frequency of 40kHz and a gradually decreasing power density is added. After the ultrasonic power density decreases to 0.1W / mL, the ozone concentration is increased at an increase rate of 4mg / L per minute.

[0052] The initial power density of the ultrasound is 0.5 W / mL, the attenuation rate is x W / mL, and the ultrasound co-processing time is t, satisfying the following formula:

[0053]

[0054] With constant i set to 1 and x set to 0.1 W / mL, t = 4 min was calculated.

[0055] Example 16: The difference between this example and Example 15 is that the constant i is 1 and x is 0.2 W / mL, and the calculated t = 2 min.

[0056] Example 17: The difference between this example and Example 15 is that the constant i is 2 and x is 0.1 W / mL, and the calculated t = 8 min.

[0057] Example 18: The difference between this example and Example 15 is that the constant i is 2 and x is 0.2 W / mL, and the calculated t = 4 min.

[0058] Example 19: This example differs from Example 15 in that the ozone concentration is increased at an increase rate of 2 mg / L per minute.

[0059] Example 20: This example differs from Example 15 in that the ozone concentration is increased at an increase rate of 5 mg / L per minute.

[0060] Application Experiment Example:

[0061] Soluble organic matter was extracted from sludge samples from a certain area of ​​the city using the extraction methods described in the embodiments. The DOC concentration in the separated liquid was determined using a TOC analyzer, with units of mg / L. The calculation formula is as follows:

[0062]

[0063] The formula for the total extraction rate is as follows:

[0064]

[0065] The total organic matter content of the sludge was determined by calcination at 550℃; the results of DOM extraction rate determination are shown in Table 1 below.

[0066] Table 1 Extraction rate of soluble organic matter from sludge in each example.

[0067] project DOM extraction rate project DOM extraction rate Example 1 85.69％ Example 11 85.56％ Example 2 84.95％ Example 12 88.43％ Example 3 85.71％ Example 13 88.32％ Example 4 84.87％ Example 14 88.41％ Example 5 85.74％ Example 15 90.72％ Example 6 85.11％ Example 16 90.67％ Example 7 85.69％ Example 17 90.73％ Example 8 85.08％ Example 18 90.71％ Example 9 85.27％ Example 19 90.70％ Example 10 85.49％ Example 20 90.55％

[0068] As shown in Table 2 above, the extraction rate of soluble organic matter in sludge using the extraction methods of the various embodiments of the present invention can reach 85-90%. To compare and verify the extraction effect of the extraction method of the present invention, an oxidation-membrane separation combined extraction method was used, employing low-temperature oxidation pretreatment (Fenton's reagent) combined with inorganic ceramic membrane concentration. The DOM recovery rate was measured as shown in Table 2 below.

[0069] Table 2 shows the extraction rate of soluble organic matter from the sludge in the control group.

[0070] project DOM extraction rate Control (Oxidation-membrane separation combined method) 60.52％

[0071] As shown in the table above, the DOM extraction rate of sludge samples from a certain area of ​​the city using the existing extraction method is only 60.52%, which is far lower than the extraction efficiency of the extraction method of the present invention. The extraction efficiency of the extraction method of the present invention is about 25-30% higher than that of the present invention.

[0072] Furthermore, a comparison of the results in Table 1 reveals that different extraction methods and parameters have a certain impact on the DOM extraction rate. A detailed comparative analysis is as follows:

[0073] Analysis 1: Examples 2-11 all involve extraction methods with different parameters than Example 1. A comparison of Examples 2 and 3 with Example 1 shows that micropore activation treatment of sludge for different durations has a certain impact on DOM extraction rate. Example 3 showed the best micropore activation effect, but the difference in DOM extraction rate between it and Example 1 was only 0.02%. Example 3 used a longer micropore activation treatment time. Therefore, considering both economic efficiency and extraction efficiency, Example 1 has a better overall extraction effect. A comparison of Examples 4 and 5 with Example 1 shows that different acoustic pressure pulse (APP) crushing treatments of sludge have a certain impact on DOM extraction rate. Example 5 showed the best APP crushing effect, but the difference in DOM extraction rate between it and Example 1 was only 0.05%. Example 5 used APP crushing treatments with larger parameters. From the perspectives of economy and extraction efficiency, Example 1 shows a better overall extraction effect. A comparison of Examples 6 and 7 with Example 1 shows that different ozone treatments on the pretreated sludge have a certain impact on the DOM extraction rate. Examples 1 and 7 show the best ozone treatment effect, but Example 7 uses a longer ozone contact time and membrane pressure; therefore, Example 1 has a better overall extraction effect. A comparison of Examples 8 and 9 with Example 1 shows that applying different pulse voltages to the separated liquid has a certain impact on the DOM extraction rate, with the pulse voltage parameters in Example 1 being the optimal. A comparison of Examples 10 and 11 with Example 1 shows that different nitrogen cyclone drying treatments on the concentrated separated liquid have a certain impact on the DOM extraction rate, with the nitrogen cyclone drying parameters in Example 1 being the optimal.

[0074] Analysis 2: Examples 12-14 are all based on Example 1, where the sludge after microporous activation treatment was treated with a pulsed DC electric field. A comparison between Example 12 and Example 1 shows that by utilizing the directional alignment of the electric field, a pulsed DC electric field can be used to treat the sludge after microporous activation treatment. Under the electrophoretic enrichment effect, negatively charged dissolved organic matter migrates and aggregates towards the positive electrode, thereby enhancing the subsequent extraction effect of DOM in the sludge. A comparison between Examples 13, 14 and Example 12 shows that different pulsed DC electric field treatment parameters have a certain impact on the DOM extraction rate, with the pulsed DC electric field treatment parameters of Example 12 being the optimal.

[0075] Analysis 3: Examples 15-20 are all based on Example 1, optimizing ozone treatment by employing controllable ultrasonic synergistic treatment to enhance DOM extraction rate. A comparison of Example 15 and Example 1 shows that using ultrasonic synergistic assistance in the early stages of ozone introduction significantly enhances the ozone treatment effect on sludge and improves organic matter dissolution while simultaneously utilizing ultrasonic synergistic treatment in the initial stage of ozone introduction. A comparison of Examples 16, 17, and 18 with Example 15 shows that, under the calculation of the above formula, the DOM extraction rate of each example is basically the same. Therefore, corresponding parameters can be selected according to actual production conditions to achieve similar DOM extraction effects. A comparison of Examples 19 and 20 with Example 15 shows that different ozone boosting rates have a certain impact on the DOM extraction rate, with Example 15 exhibiting the best DOM extraction rate.

Claims

1. A method for extracting soluble organic matter from sludge, characterized in that, Includes the following steps: S1. The sludge undergoes micropore activation treatment, wherein the micropore activation treatment method is as follows: sludge with a moisture content of 80-90% is placed in a subcritical carbon dioxide environment, and the pressure is maintained at 8 MPa for 25-40 minutes; subsequently, it is placed in a constant temperature bath at 18-25℃, using a frequency of 1.0-1.5 MHz and a sound intensity of 0.5-1 W / cm². 2 The focused ultrasound, combined with the alternating action of 3~6MPa hydraulic pulses for 40~50min, yields pretreated sludge. The alternation of the focused ultrasound and hydraulic pulses is as follows: each alternation cycle includes 10~12s of focused ultrasound sound pressure breaking and 5~7s of hydraulic pulse hydraulic impact. S2. Ozone is continuously introduced into the pretreated sludge at a low temperature of 5℃ for 15-25 minutes to promote the dissolution of organic matter. The sludge is then separated by passing it through a ceramic microfiltration membrane and an organic nanofiltration membrane to obtain the separated liquid. S3. Apply pulsed voltage to the separated liquid for 35~45 minutes; The temperature of the concentration device was then maintained at 4°C, and the separated liquid was concentrated to 1 / 5 of its original volume by vacuum evaporation to obtain concentrated separated liquid; S4. The concentrated separation liquid is processed using a -30℃ nitrogen cyclone drying system to obtain DOM powder with a water content of ≤3%.

2. The method for extracting soluble organic matter from sludge as described in claim 1, characterized in that, After being kept in the subcritical carbon dioxide environment for 10-15 minutes, the sludge is treated with a pulsed DC electric field for 90-150 minutes. The field strength of the pulsed DC electric field is 12-15 V / cm, the pulse width is 1 ms, and the interval is 3-5 ms.

3. The method for extracting soluble organic matter from sludge as described in claim 1, characterized in that, During ozone introduction, ultrasonic treatment with a frequency of 40 kHz and a gradually decreasing power density was applied. After the ultrasonic power density decreased to 0.1 W / mL, the ozone concentration was increased at an increase rate of 2-5 mg / L per minute. The initial power density of the ultrasound is 0.5 W / mL, the attenuation rate is x W / mL / min, and the ultrasound co-processing time is t, satisfying the following formula: ， ∈[0.1，0.2] Where, constant Take 1 or 2, 0.4 units are W / mL.

4. The method for extracting soluble organic matter from sludge as described in claim 1, characterized in that, The pulse voltage is applied using a titanium-based ruthenium-iridium electrode, with a current density of 0.5~1 A / m. 2 The pulse voltage is 5V for 8~15s in the positive direction and 3V for 3~8s in the reverse direction.

5. The method for extracting soluble organic matter from sludge as described in claim 1, characterized in that, The operating pressure of the ceramic microfiltration membrane is 2.0~3.0 bar, and the operating pressure of the organic nanofiltration membrane is 8.0~10.0 bar.

6. The method for extracting soluble organic matter from sludge as described in claim 1, characterized in that, The concentrated and separated liquid was treated using a -30℃ nitrogen cyclone drying system, wherein the gas velocity of the nitrogen cyclone drying system was 10~12m / s and the residence time was 12~15s.

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