A method for treating low-level radioactive wastewater

Abstract

The present invention provides a method for treating low-level radioactive wastewater, which comprises the following steps: flotation slag removal: introducing dissolved air water into the bottom of the flotation tank to form slag on the water surface, collecting the slag, and obtaining a first intermediate liquid; primary filtration: inputting the first intermediate liquid into the filter to obtain a second intermediate liquid; secondary filtration: inputting the second intermediate liquid into a ceramic membrane device, and obtaining a third intermediate liquid after filtration, wherein the filtration size of the secondary filtration step is smaller than the filtration size in the primary filtration step; reverse osmosis treatment: performing reverse osmosis treatment on the third intermediate liquid to obtain a purified liquid. The treatment method in the embodiment of the present invention filters out pollutants in order from large to small sizes, which, on the one hand, ensures the filtration effect of pollutants in wastewater and reduces the content of TSS and TOC; on the other hand, reduces the probability of damaging the filter medium due to excessive pollutants to be filtered.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a method for treating low-level radioactive wastewater. Background Art

[0002] Nuclear waste reprocessing plants produce a large amount of non-process low-level radioactive wastewater during the treatment of nuclear waste. The so-called non-process low-level radioactive wastewater refers to the wastewater produced in the reprocessing plant except for the main processes involved in the treatment of nuclear waste, and its radioactivity is less than 10 6 Bq / m 3 (Becquerel per cubic metre). The sources of wastewater include desorption and decontamination liquid from process plants, desorption and decontamination liquid from three waste plants, floor washing water in the orange area of ​​process plants, shower water and laundry water, etc. Non-process low-level radioactive wastewater has the characteristics of large annual production, complex composition and a wide variety of contaminating nuclides.

[0003] Nuclear waste includes spent fuel. Non-process low-level wastewater generated by spent fuel reprocessing plants mainly contains suspended solids, colloidal particles, surfactants, organic solvents, soluble complexing agents and radiolysis products of salt-free reagents, etc. Colloidal particles have strong surface activity and can adsorb radioactive nuclides. Surfactants have strong complexing ability and can complex elements such as actinides and technetium.

[0004] In the relevant technology, the three-stage treatment process of chemical precipitation, ion exchange and evaporation concentration is mainly used to remove radioactive nuclides in radioactive wastewater, so that the radioactivity level of the wastewater reaches the emission limit. However, the evaporator may boil over during the evaporation and concentration of wastewater in this treatment process, making it difficult to achieve the expected effect of evaporation and purification of radioactive wastewater; solid suspended matter, colloidal particles and other substances contained in the wastewater are easy to block the pores in the filtration channel and the ion exchange channel, reducing the purification effect; and the soluble complexing agents, salt-free reagent radiolysis products and other substances remaining in the incompletely purified wastewater are complexed with radioactive elements to form soluble radioactive nuclides, which have poor curing effect with cement, and are easily dissolved in water after contact with groundwater and released from cement, causing pollution. Summary of the invention

[0005] In view of this, the embodiments of the present application hope to provide a method for treating low-level radioactive wastewater that can enhance the solidification effect of cement on radioactive elements.

[0006] To achieve the above purpose, the technical solution of the embodiment of the present application is implemented as follows:

[0007] The present invention provides a method for treating low-level radioactive wastewater, which comprises the following steps:

[0008] Air flotation slag removal: introducing dissolved air water into the bottom of the air flotation tank to form slag on the water surface, collecting the slag and obtaining the first intermediate liquid;

[0009] Primary filtration: inputting the first intermediate liquid into a filter to obtain a second intermediate liquid;

[0010] Secondary filtration: inputting the second intermediate liquid into a ceramic membrane device to obtain a third intermediate liquid after filtration, wherein the filtration size of the secondary filtration step is smaller than the filtration size of the primary filtration step;

[0011] Reverse osmosis treatment: The third intermediate liquid is subjected to reverse osmosis treatment to obtain a purified liquid.

[0012] In some embodiments, before the flotation slag removal, the treatment method includes: adding a coagulant to the wastewater.

[0013] In some embodiments, the coagulant includes polyaluminium chloride and polyacrylamide, the concentration range of the polyaluminium chloride is 300mg / L to 1000mg / L, and the concentration range of the polyacrylamide is less than or equal to 2mg / L.

[0014] In some embodiments, the primary filtration specifically includes:

[0015] The first intermediate liquid is input into a rotating scraper device to obtain the second intermediate liquid, and the scraper of the rotating scraper device is driven to rotate to scrape off the filter residue attached to the filter membrane of the rotating scraper device.

[0016] In some embodiments, the primary filtration step further includes: backwashing the filter membrane to obtain first water to be treated; and the treatment method includes: oxidizing the first water to be treated and the filter residue.

[0017] In some embodiments, the secondary filtering step further comprises:

[0018] During the secondary filtration process, the ceramic membrane of the ceramic membrane device is driven to rotate.

[0019] In some embodiments, the secondary filtration step further includes: controlling the ceramic membrane to stop rotating, and inputting compressed air in the opposite direction of the second intermediate liquid flowing through the ceramic membrane; and / or,

[0020] The secondary filtration step also includes: controlling the ceramic membrane to stop rotating, inputting backwash water in the opposite direction of the second intermediate liquid flowing through the ceramic membrane, and obtaining second water to be treated after the backwash water flows through the ceramic membrane; the treatment method includes: oxidizing the second water to be treated.

[0021] In some embodiments, the reverse osmosis treatment step further includes: collecting the third intermediate liquid that has not passed through the reverse osmosis membrane and using it as the third water to be treated; and the treatment method includes: subjecting the third water to be treated to oxidation treatment.

[0022] In some embodiments, the oxidation treatment comprises:

[0023] Preparation of supercritical water;

[0024] The material to be treated is introduced into a reaction container filled with the supercritical water.

[0025] In some embodiments, the preparation of supercritical water includes: adding water to a supercritical oxidation water treatment device and increasing the pressure, maintaining the pressure in the range of 20MPa-22MPa, maintaining the pressure for 10min-60min and then heating, heating to 300℃-370℃, injecting oxygen and sucrose to obtain the supercritical water at 470℃-570℃.

[0026] In some embodiments, the oxidation treatment is chemical oxidation, which includes: adding an oxidant to the substance to be treated, and the oxidant includes hydrogen peroxide and ferrous sulfate.

[0027] In some embodiments, the primary filtration step is used to remove solid particles and suspended solids larger than 20 μm; the secondary filtration step is used to remove colloidal particles larger than 0.2 μm.

[0028] The treatment method in the embodiment of the present invention combines multiple filtering methods to filter out pollutants in the wastewater in order from large to small sizes, thereby reducing the filtering load of each treatment step, so that each step can effectively play a filtering role. On the one hand, the filtering effect of pollutants in the wastewater is guaranteed, and the content of TSS and TOC can be effectively reduced, so that the TSS content in the purified liquid reaches below 10 mg / L, and the TOC removal rate reaches more than 90%; on the other hand, the probability of damaging the filter medium due to too many pollutants that need to be filtered is reduced, the frequency of maintenance is reduced, and the efficiency of the filtering operation is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The figure is a flow chart of a processing method in one embodiment of the present invention. DETAILED DESCRIPTION

[0030] It should be noted that, in the absence of conflict, the embodiments and technical features in the embodiments of the present application can be combined with each other, and the detailed description in the specific implementation method should be understood as an explanation of the purpose of the present application and should not be regarded as an improper limitation on the present application.

[0031] The present invention provides a method for treating low-level radioactive wastewater. In some embodiments, referring to Figure 1 , the processing method comprises the following steps:

[0032] S1: Air flotation slag removal: introducing dissolved air water into the bottom of the air flotation tank to form slag on the water surface, collecting the slag, and obtaining the first intermediate liquid.

[0033] The principle of the flotation slag removal step is: the dissolved air water is introduced into the bottom of the flotation tank. The dissolved air water is formed by introducing compressed air into the wastewater to be treated. The compressed air forms dispersed tiny bubbles in the wastewater. The bubbles can act as carriers to adhere to the solid particles containing hydrophobic groups or liquid containing hydrophobic groups suspended in the wastewater, and form a mixture with a density lower than that of the wastewater. The mixture floats to the surface of the wastewater and aggregates to form scum. After the scum is removed from the water surface, the purpose of reducing pollutants in the wastewater is achieved.

[0034] Therefore, through flotation slag removal, large-particle solid suspended matter and part of the surfactant in the wastewater can be effectively reduced, thereby discharging the radioactive substances complexed with them and obtaining the first intermediate liquid with significantly reduced low-level radioactive pollutant content.

[0035] It is understandable that when the dissolved air water is introduced into the bottom of the flotation tank of the flotation device for flotation slag removal, the heavy solid particles in the wastewater that are insoluble in water will sink to the bottom of the flotation tank. Therefore, a slag discharge channel is provided at the bottom of the flotation tank for discharging the above solid particles.

[0036] It is understandable that the flotation device separates the scum from the waste water by hydraulic separation. Specifically, a slag discharge port is provided at the top of the flotation tank of the flotation device, and the waste water on the surface can overflow from the slag discharge port and take away the scum. Therefore, there is no need to set up a mechanical scraper to scrape off the scum, which simplifies the structure of the flotation device on the one hand, and prevents the scum containing radioactive substances from remaining in the mechanical scraper on the other hand, thereby affecting the safety of the staff during the inspection and maintenance process.

[0037] It is understandable that an adjustable baffle may be provided at the edge of the slag discharge port, and the speed of slag overflow may be controlled by adjusting the position and angle of the baffle.

[0038] It is understandable that a sealing cover is provided on the top of the flotation tank of the flotation device to reduce the liquid splashing caused by the bubbles floating to the surface of the wastewater and reduce the probability of the spread of radioactive pollutants.

[0039] S2: primary filtration: inputting the first intermediate liquid into the filter to obtain the second intermediate liquid;

[0040] After the first intermediate liquid passes through the filter, the solid particles contained in the first intermediate liquid can be reduced, thereby reducing the content of pollutants.

[0041] S3: secondary filtration: the second intermediate liquid is input into the ceramic membrane device, and a third intermediate liquid is obtained after filtration, wherein the filtration size in the secondary filtration step is smaller than the filtration size in the primary filtration step;

[0042] The second intermediate liquid passes through the ceramic membrane in the ceramic membrane device, thereby filtering the colloidal particles in the second intermediate liquid and reducing the content of pollutants.

[0043] The secondary filtration step has a smaller filter size than the primary filtration step, so that the secondary filtration step can filter out pollutants that pass through the filter in the primary filtration step, thereby improving the purification effect.

[0044] S4: Reverse osmosis treatment: The third intermediate liquid is subjected to reverse osmosis treatment to obtain a purified liquid.

[0045] The principle of reverse osmosis treatment: pressure is applied to the third intermediate liquid located on one side of the reverse osmosis membrane, and the applied pressure is greater than the osmotic pressure of the third intermediate liquid, so that the third intermediate liquid passes through the reverse osmosis membrane to obtain a purified liquid that has been filtered, while the pollutants still remain on one side of the third intermediate liquid.

[0046] The pollutants such as the surfactant, organic solvent, soluble complexing agent and radiolysis product of the salt-free reagent remaining in the third intermediate liquid can be effectively removed by reverse osmosis treatment.

[0047] The treatment method in the embodiment of the present invention combines multiple filtering methods to filter out pollutants in the wastewater in order of size from large to small, thereby reducing the filtering load of each treatment step and enabling each step to effectively play a filtering role. On the one hand, the filtering effect on pollutants in the wastewater is guaranteed, and the content of TSS (Total Suspended Solids) and TOC (Total Organic Carbon) can be effectively reduced, so that the TSS content in the purified liquid reaches below 10 mg / L (milligrams per liter) and the TOC removal rate reaches more than 90%; on the other hand, the probability of damaging the filter medium due to excessive pollutants that need to be filtered is reduced, the frequency of maintenance is reduced, and the efficiency of the filtering operation is improved.

[0048] The purified liquid obtained after the treatment method in the embodiment of the present invention can be transported to the subsequent cement solidification process. Since the solid suspended matter, colloidal particles and other substances with complexing ability in the purified liquid have been filtered out, the radioactive elements in the purified liquid can be stably retained in the concrete, reducing the probability of radioactive elements precipitating out of the concrete after long-term storage.

[0049] It is understood that additives may be added to the wastewater to improve the effect of removing pollutants in the flotation deslagging step. For example, in some embodiments, before the flotation deslagging, the treatment method includes: adding a coagulant to the wastewater.

[0050] By adding coagulants, some substances in the wastewater can be condensed with the coagulants to produce flocs, which can be separated from the water, making it easier for bubbles to adhere to more pollutants and improving the purification effect of the flotation deslagging step.

[0051] In some embodiments, the coagulant includes polyaluminium chloride and polyacrylamide, the concentration range of polyaluminium chloride is 300mg / L to 1000mg / L, and the concentration range of polyacrylamide is less than or equal to 2mg / L. By using a mixture of polyaluminium chloride and polyacrylamide in the above concentration range as a coagulant, the flocculation effect of the coagulant on the solid suspended matter in the wastewater can be further improved, and the adhesion effect with the bubbles can be improved.

[0052] It should be noted that the scum collected in the flotation scum removal step can be further purified or sealed according to its specific composition and radioactivity, which will not be elaborated here.

[0053] It is understandable that in the primary filtration step, the first intermediate liquid will leave some pollutants on the filter membrane after passing through the filter membrane, which will affect the filtration effect of the filter membrane after long-term use. Therefore, the pollutants on the filter membrane need to be cleaned.

[0054] In some embodiments, primary filtering specifically includes:

[0055] The first intermediate liquid is input into the rotating scraper device to obtain the second intermediate liquid, and the scraper of the rotating scraper device is driven to rotate to scrape off the filter residue attached to the filter membrane of the rotating scraper device.

[0056] A filter cartridge formed by curling a filter membrane is provided in the rotating scraper device, and a drainage channel is formed around the inner wall of the filter cartridge, which is connected to the outside. The scraper rotates along the circumference of the outer wall of the filter cartridge and contacts the outer wall of the filter cartridge, and the first intermediate liquid passes through the filter cartridge from the outer wall of the filter cartridge into the drainage channel to obtain the second intermediate liquid. The scraper is continuously rotated to scrape off the filter residue remaining on the outer wall of the filter cartridge, thereby reducing the influence of the filter residue attached to the filter membrane on the first intermediate liquid passing through the filter membrane and improving the filtering effect.

[0057] It is understandable that after long-term use, the pollutants in the first intermediate liquid can penetrate into the filter membrane and are difficult to be scraped off by a scraper. Therefore, other means are needed to remove the pollutants attached to the inside of the filter membrane, thereby extending the service life of the filter membrane and maintaining the filtering effect of the filter membrane.

[0058] In some embodiments, the secondary filtration step further includes: controlling the ceramic membrane to stop rotating, and inputting compressed air in the opposite direction of the second intermediate liquid flowing through the ceramic membrane. The compressed air can blow out the pollutants attached to the inside of the filter membrane.

[0059] In some embodiments, the primary filtration step further includes: backwashing the filter membrane to obtain first treated water. Backwashing is to input water flow in the opposite direction of the first intermediate liquid passing through the filter membrane, and the pollutants in the filter membrane are separated from the filter membrane under the flushing of the water flow to form filter residues, thereby achieving the effect of cleaning the filter membrane and extending the life of the filter membrane.

[0060] It is understood that the first treated water and the filter residue collected after the primary filtration step contain significantly fewer pollutants than the first intermediate liquid, and therefore can be further treated to meet the requirements of the cement curing process.

[0061] In some embodiments, the treatment method includes: subjecting the first water to be treated and the filter residue to oxidation treatment. Through the oxidation treatment, the organic matter in the first water to be treated and the filter residue is oxidized and decomposed, effectively reducing the ability of the residual organic matter in the first water to be treated and the filter residue to complex with the radioactive elements. The first water to be treated and the filter residue can enter the cement curing process after the oxidation treatment, reducing the probability of radioactive elements precipitating from the concrete. At the same time, the first water to be treated and the filter residue enter the cement curing process together with the purified liquid, avoiding the use of other additional processes or storage devices for treatment, and simplifying the process flow.

[0062] It is understandable that in the secondary filtration step, the filtration method of the ceramic membrane in the ceramic membrane device can be further optimized to improve the filtration effect.

[0063] In some embodiments, the secondary filtering step further comprises:

[0064] During the secondary filtration process, the ceramic membrane of the ceramic membrane device is driven to rotate.

[0065] The ceramic membrane rotates at high speed along with the rotating shaft in the ceramic membrane device, thereby generating a high shear rate on the surface of the ceramic membrane and forming a vortex sweep flow, making the filter cake layer on the surface of the ceramic membrane very thin and exposed, thereby reducing the probability of contaminant blockage and the probability of obstructing the flow of permeate flow in the ceramic membrane and improving the filtration effect.

[0066] It is understandable that after long-term use, the pollutants attached to the ceramic membrane need to be removed in order to maintain the filtering effect of the ceramic membrane and extend the service life of the ceramic membrane.

[0067] In some embodiments, the secondary filtration step further includes: controlling the ceramic membrane to stop rotating, inputting backwash water in the opposite direction of the second intermediate liquid flowing through the ceramic membrane, and obtaining second water to be treated after the backwash water flows through the ceramic membrane. The pollutants in the ceramic membrane are separated from the ceramic membrane by the backwash water flow to form the second water to be treated, thereby achieving the effect of cleaning the ceramic membrane.

[0068] It can be understood that, since the pollutants in the second intermediate liquid have been significantly reduced in the secondary filtration step, the obtained second water to be treated contains fewer pollutants and can be used in the subsequent cement solidification process after treatment.

[0069] In some embodiments, the treatment method includes: subjecting the second water to be treated to oxidation treatment. Through oxidation treatment, the organic matter in the second water to be treated is oxidized and decomposed, effectively reducing the ability of the residual organic matter in the second water to be treated to complex with radioactive elements, so that the second water to be treated can enter the cement curing process after oxidation treatment, reducing the probability of radioactive elements precipitating from concrete. At the same time, the second water to be treated is allowed to enter the cement curing process together with the purified liquid, avoiding the use of other additional processes or storage devices for treatment, thereby simplifying the process flow.

[0070] It can be understood that, since the pollutants in the third intermediate liquid have been significantly reduced in the reverse osmosis step, the third intermediate liquid treated by reverse osmosis can be used in the subsequent cement solidification process after treatment.

[0071] In some embodiments, the reverse osmosis treatment step further includes: collecting the third intermediate liquid that has not passed through the reverse osmosis membrane and using it as the third water to be treated; the treatment method includes: subjecting the third water to be treated to oxidation treatment. Through oxidation treatment, the organic matter in the third water to be treated is oxidized and decomposed, effectively reducing the ability of the residual organic matter in the third water to be treated to complex with radioactive elements, so that the third water to be treated can enter the cement curing process after oxidation treatment, reducing the probability of radioactive elements precipitating from concrete. At the same time, the third water to be treated is allowed to enter the cement curing process together with the purified liquid, avoiding the use of other additional processes or storage devices for treatment, thereby simplifying the process flow.

[0072] It is understandable that oxidation treatment can effectively reduce the TOC content in pollutants, and the oxidation treatment method can be selected from the perspectives of cost, time and by-products.

[0073] For example, in some embodiments, the oxidation treatment includes:

[0074] Preparation of supercritical water;

[0075] The material to be treated is introduced into a reaction vessel filled with supercritical water.

[0076] Supercritical water refers to water at a temperature exceeding 374°C (degree centigrade) and a pressure exceeding 22Mpa (mega pascal). Supercritical water has a strong oxidizing ability and can quickly oxidize organic matter to form small molecular compounds such as carbon dioxide, water and salts under high temperature and high pressure conditions, thereby reducing the ability of residual organic matter to complex with radioactive elements, so that the product oxidized by supercritical water can enter the cement curing process together with the purified liquid.

[0077] In some embodiments, preparing supercritical water includes: adding water to a reaction vessel in a supercritical oxidation water treatment device and increasing the pressure, maintaining the pressure in the range of 20MPa-22MPa, maintaining the pressure for 10min (minute)-60min, and then heating, heating to 300℃-370℃, injecting oxygen and sucrose, and obtaining supercritical water at 470℃-570℃. After the supercritical oxidation water treatment device is heated to 300℃-370℃, it is difficult to further increase the temperature, so sucrose is added, and the effect of sucrose being pyrolyzed and generating a large amount of heat in a high temperature environment is utilized, so that the temperature in the supercritical oxidation water treatment device is further increased until the expected supercritical temperature is reached. At this temperature, oxygen acts as an oxidant to react with organic matter in a supercritical oxidation reaction, causing the organic matter to be pyrolyzed and gasified, thereby achieving the purpose of oxidizing the organic matter.

[0078] It is understood that in some embodiments, the oxidation treatment is chemical oxidation, which includes: adding an oxidant to the substance to be treated, the oxidant including hydrogen peroxide and ferrous sulfate. The mixed solution composed of hydrogen peroxide and divalent iron ions has strong oxidizing properties, which can oxidize organic matter in the pollutants to form inorganic compounds, reduce the ability of residual organic matter to complex with radioactive elements, and allow the product after supercritical water oxidation to enter the cement curing process together with the purified liquid.

[0079] It is understood that the above-mentioned substances to be treated include but are not limited to scraps, first water to be treated, second water to be treated and third water to be treated, and also include other by-products in the treatment method, such as reflux water generated by the water pumps in the primary filtration, secondary filtration and reverse osmosis treatment processes after stopping pumping; and reverse osmosis membrane flushing water generated by flushing the reverse osmosis membrane.

[0080] It is understood that there should be a significant difference in the size of pollutants that can be filtered between the primary filtration step and the secondary filtration step.

[0081] Specifically, in some embodiments, the primary filtration step is used to remove solid particles and suspended solids larger than 20 μm (micrometer); the secondary filtration step is used to remove colloidal particles larger than 0.2 μm. The primary filtration step and the secondary filtration step are respectively aimed at different types of pollutants, reducing the possibility of larger solid particles and suspended solids clogging the ceramic membrane. In addition, it is convenient to find that the content of solid particles and suspended solids exceeds the standard or the content of colloidal particles exceeds the standard during the subsequent detection of the purified liquid to determine the steps of the treatment method where problems occur, so that the staff can conduct timely maintenance.

[0082] The various embodiments / implementations provided in this application can be combined with each other without causing any contradiction.

[0083] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for treating low-level radioactive wastewater, characterized in that: The processing method comprises the following steps: Air flotation slag removal: introducing dissolved air water into the bottom of the air flotation tank to form slag on the water surface, collecting the slag and obtaining the first intermediate liquid; Primary filtration: inputting the first intermediate liquid into a rotating scraper device to obtain a second intermediate liquid, driving the scraper of the rotating scraper device to rotate to scrape off the filter residue attached to the filter membrane of the rotating scraper device, and backwashing the filter membrane to obtain the first water to be treated; Secondary filtration: inputting the second intermediate liquid into the ceramic membrane device, driving the ceramic membrane of the ceramic membrane device to rotate, obtaining a third intermediate liquid after filtration, controlling the ceramic membrane to stop rotating, inputting backwash water in the opposite direction of the second intermediate liquid flowing through the ceramic membrane, and obtaining second water to be treated after the backwash water flows through the ceramic membrane, wherein the filtration size of the secondary filtration step is smaller than the filtration size in the primary filtration step; Reverse osmosis treatment: subjecting the third intermediate liquid to reverse osmosis treatment to obtain a purified liquid; collecting the third intermediate liquid that has not passed through the reverse osmosis membrane and using it as the third water to be treated; The filter residue, the first water to be treated, the second water to be treated and the third water to be treated are subjected to oxidation treatment and then enter the cement solidification process together with the purified liquid; The oxidation treatment comprises: Preparation of supercritical water; Introducing the substance to be treated into a reaction container filled with the supercritical water; Alternatively, the oxidation treatment is chemical oxidation, which includes: adding an oxidant to the substance to be treated, and the oxidant includes hydrogen peroxide and ferrous sulfate.

2. The processing method according to claim 1, characterized in that: Before the flotation slag removal, the treatment method includes: adding a coagulant to the wastewater.

3. The processing method according to claim 2, characterized in that: The coagulant comprises polyaluminium chloride and polyacrylamide, the concentration range of the polyaluminium chloride is 300mg / L to 1000mg / L, and the concentration range of the polyacrylamide is less than or equal to 2mg / L.

4. The processing method according to claim 1, characterized in that: The secondary filtration step further includes: controlling the ceramic membrane to stop rotating and inputting compressed air in the opposite direction of the second intermediate liquid flowing through the ceramic membrane.

5. The processing method according to claim 1, characterized in that: The preparation of supercritical water includes: adding water to a supercritical oxidation water treatment device and increasing the pressure, maintaining the pressure in the range of 20MPa-22MPa, maintaining the pressure for 10min-60min and then heating, heating to 300℃-370℃, injecting oxygen and sucrose to obtain the supercritical water at 470℃-570℃.

6. The processing method according to claim 1, characterized in that: The primary filtration step is used to remove solid particles and suspended solids larger than 20 μm; the secondary filtration step is used to remove colloidal particles larger than 0.2 μm.

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