Surface treatment method, anti-pollution ceramic membrane, application of anti-pollution ceramic membrane and sewage treatment method

Abstract

The invention discloses a surface treatment method, an anti-pollution ceramic membrane, application of the anti-pollution ceramic membrane and a sewage treatment method, and the surface treatment method comprises the following steps: S1, carrying out modification treatment on the surface of a material to obtain a hydrophilic modified ceramic membrane; s2, carrying out anti-pollution treatment on the surface of the modified ceramic membrane to obtain an anti-pollution ceramic membrane; wherein the ceramic membrane is a nanofiltration ceramic membrane, and the aperture of the ceramic membrane is 1nm-5nm. According to the surface treatment method disclosed by the invention, the ceramic membrane is prepared into the hydrophilic modified ceramic membrane, so that sludge, microorganisms or colloidal substances are not easy to adhere to the ceramic membrane; and secondly, through anti-pollution treatment, accumulation of pollutants on the surface of the ceramic membrane can be further reduced, so that the ceramic membrane can keep permeability for a long time, the ceramic membrane can be effectively prevented from being abraded by impurities and particulate matters in sewage, and the service life of the ceramic membrane is prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of sewage treatment, more particularly to a surface treatment method, an anti-pollution ceramic membrane and application thereof and a sewage treatment method. BACKGROUND

[0002] Domestic sewage is wastewater generated in daily life of residents, including kitchen, bathing, laundry and toilet drainage, etc. It contains a large amount of organic matter, suspended solids, nitrogen and phosphorus nutrients and pathogenic microorganisms. If it is directly discharged without treatment, it will cause water pollution and eutrophication, endangering the ecological environment and human health. Therefore, it is of great significance to effectively purify and treat domestic sewage.

[0003] At present, activated sludge method is generally used for domestic sewage treatment. This method can achieve purification by microbial metabolic decomposition of organic pollutants. Although the treatment effect is good, there are still some deficiencies: the process flow is complex, the land occupation area is large, the energy consumption is high, it is sensitive to temperature and load changes, and it is easy to cause water quality fluctuation; in addition, the system needs to maintain a high level of dissolved oxygen and sludge concentration, the operation and management requirements are high, the sludge amount is large and the subsequent treatment cost is high. In recent years, ceramic membrane filtration technology has also been applied to domestic sewage treatment. It can efficiently intercept suspended solids, colloids and microorganisms in sewage through its microporous structure, and has the advantages of corrosion resistance, high temperature resistance and long service life. However, the surface of traditional ceramic membrane is easy to be eroded and rubbed by particles in water, and is easy to be worn out after long-term operation, affecting the structural integrity and service life of the membrane. In addition, under the condition of high concentration of organic matter or colloidal substance, the surface is still easy to form a deposition layer of pollutants, resulting in flux decay and increased energy consumption.

[0004] Therefore, how to provide a ceramic membrane with high anti-pollution performance, high filtration efficiency and improved anti-wear performance has become a technical problem to be solved in the field. SUMMARY

[0005] Therefore, the present application provides a surface treatment method, an anti-pollution ceramic membrane and application thereof and a sewage treatment method.

[0006] According to a first aspect of the present application, a surface treatment method of a ceramic membrane is provided, which comprises: S1. modifying the surface of the material to obtain a hydrophilic modified ceramic membrane; S2. anti-pollution treatment is performed on the surface of the modified ceramic membrane to obtain an anti-pollution ceramic membrane; wherein the ceramic membrane is a nanofiltration ceramic membrane with a pore size of 1-5 nm.

[0007] Preferably, the step S1 comprises: S11. plasma cleaning the ceramic membrane to be treated to remove pollutants on the surface of the ceramic membrane and expose active sites on the surface of the ceramic membrane; S12. grafting treatment is performed on the cleaned ceramic membrane.

[0008] Preferably, the steps S11 and S12 comprise: performing plasma cleaning on the ceramic membrane in a first gas atmosphere, the first gas being one or more of oxygen, hydrogen and inert gas, preferably the inert gas being argon and nitrogen.

[0009] Preferably, the flow rate of the first gas is 10 sccm~300 sccm, preferably the flow rate of the first gas is 30 sccm~150 sccm; the working gas pressure is 10 Pa~100 Pa, preferably the working gas pressure is 30 Pa~50 Pa.

[0010] Preferably, the discharge power of the plasma cleaning treatment is 50W~300W, the discharge treatment time is 2min~20min, preferably the discharge power is 100W~200W, and the cleaning time is 5min~10min.

[0011] Preferably, the step S2 comprises: placing the modified ceramic membrane in a multi-walled carbon nanotube solution to uniformly coat the surface of the modified ceramic membrane with multi-walled carbon nanotubes; preferably, the concentration of multi-walled carbon nanotubes in the multi-walled carbon nanotube solution is 0.1g / L~2g / L, preferably 0.5g / L~1g / L; the treatment time is 5~10min.

[0012] Preferably, the step S2 comprises: drying and curing the modified ceramic membrane coated with multi-walled carbon nanotubes; the drying temperature is 50~60℃, and the time is 1~2h; the curing temperature is 200~400℃, and the time is 1~2h.

[0013] According to a second aspect of the present application, a pollution-resistant ceramic membrane prepared by a surface treatment method is provided.

[0014] According to a third aspect of the present application, an application of the pollution-resistant ceramic membrane in sewage treatment is provided.

[0015] According to a fourth aspect of the present application, a sewage treatment method is provided, which comprises: filtering sewage through a pollution-resistant ceramic membrane to obtain concentrated sludge and membrane effluent, the pollution-resistant ceramic membrane being the pollution-resistant ceramic membrane described above; preferably, the sewage treatment method comprises: filtering the sewage and / or the membrane effluent through a single-stage or multi-stage ceramic membrane; the sewage treatment method further comprises: harmless treatment of the concentrated sludge.

[0016] The surface treatment method in the present application prepares the ceramic membrane into a modified ceramic membrane with hydrophilicity, so that sludge, microorganisms or colloidal substances are not easily adhered to the ceramic membrane; secondly, through the anti-pollution treatment, the accumulation of pollutants on the surface of the ceramic membrane can be further reduced, so that the ceramic membrane can maintain permeability for a long time, and the ceramic membrane can also effectively avoid being abraded by impurities and particulate matters in the sewage, thereby prolonging the service life of the ceramic membrane.

[0017] Other features and advantages of the present application will be described in detail in the subsequent specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0018] The accompanying drawings, which form a part of the present application, are used to provide further understanding of the present application, and the illustrative embodiments of the present application and their description are used to explain the present application. In the drawings: Figure 1 is a simple flowchart of the surface treatment method according to the present application.

[0019] Figure 2 is a flowchart of the surface treatment method according to the present application.

[0020] Figure 3 is a schematic diagram of single-stage ceramic membrane filtration according to the sewage treatment method in the present application.

[0021] Figure 4 is a schematic diagram of multi-stage ceramic membrane filtration according to the sewage treatment method in the present application. DETAILED DESCRIPTION

[0022] The technical solutions of the present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0023] As shown in Figures 1-2 the first aspect of the present application, a surface treatment method of a ceramic membrane is provided, which comprises: S1. modifying the surface of the material to obtain a modified ceramic membrane with hydrophilicity; S2. performing anti-pollution treatment on the surface of the modified ceramic membrane to obtain an anti-pollution ceramic membrane; wherein the ceramic membrane is a nanofiltration ceramic membrane with a pore size of 1 nm to 5 nm.

[0024] The nanofiltration ceramic membrane in the present application is an inorganic membrane material with a nanoscale pore size, which is sintered from materials such as aluminum oxide, cobalt oxide and titanium dioxide. The above-mentioned nanofiltration ceramic membrane is a nanofiltration ceramic membrane in the prior art.

[0025] The ceramic membrane with a pore size of 1 nm to 5 nm can effectively intercept organic pollutants, bacteria and viruses, etc.; and can also effectively intercept nutrient salts such as nitrogen and phosphorus in the sewage, so as to ensure that the membrane effluent passing through the ceramic membrane meets the reuse standard or the discharge standard.

[0026] In the step S1, before the modification treatment of the ceramic membrane, the ceramic membrane is cleaned by ultrasonic wave to thoroughly remove the contaminants and impurities on the surface of the ceramic membrane, such as dirt, grease and bacteria, so as to improve the cleanliness and surface activity.

[0027] Traditionally, the ceramic membrane is used to filter sewage, and the contaminants are accumulated on the surface of the ceramic membrane in large quantities, which reduces the permeability of the ceramic membrane and affects the filtration efficiency of the sewage. In addition, the impurities in the sewage will cause abrasion to the surface of the ceramic membrane in the process of continuous filtration, which seriously reduces the service life of the ceramic membrane. Therefore, the application creatively proposes a surface treatment method of the ceramic membrane, which prepares the ceramic membrane into a modified ceramic membrane with hydrophilicity, so that the sludge, microorganisms or colloidal substances are not easy to adhere to the ceramic membrane. In addition, through the anti-pollution treatment, the accumulation of contaminants on the surface of the ceramic membrane can be further reduced, so that the ceramic membrane can maintain permeability for a long time, and the ceramic membrane can be effectively prevented from being abraded by the impurities and particulate matters in the sewage, thereby prolonging the service life of the ceramic membrane.

[0028] In the technical solution of the application, the surface of the ceramic membrane can be modified by a suitable method, and the anti-pollution treatment can be performed in a released manner.

[0029] According to a preferred embodiment of the application, the step S1 can include: S11. The ceramic membrane to be treated is cleaned by plasma to remove the contaminants on the surface of the ceramic membrane, so as to expose the active sites on the surface of the ceramic membrane; S12. The cleaned ceramic membrane is subjected to grafting treatment. Steps S11 and S12 can be performed by a suitable method to achieve the effect of cleaning the surface of the ceramic membrane and surface grafting of the ceramic membrane. Preferably, the steps S11 and S12 include: the ceramic membrane is cleaned by plasma in a first gas atmosphere, and the first gas is one or more of oxygen, hydrogen and inert gas. Preferably, the inert gas is argon and nitrogen, and more preferably, the gas is oxygen or a mixture of oxygen and argon.

[0030] More specifically, according to an operable exemplary embodiment, the steps S11 and S12 can include: the ceramic membrane to be treated is placed in a plasma cleaning machine, and the plasma cleaning machine is vacuumed to a basic vacuum state before plasma discharge cleaning treatment, and the basic vacuum pressure is preferably 5 Pa to 20 Pa. ；Subsequently, the first gas is introduced into the reaction cavity at a flow rate of 10-300 sccm, preferably 30-150 sccm. The gas flow rate and the pumping rate are adjusted to stabilize the pressure in the cavity at a working pressure of 10-100 Pa, preferably 30-50 Pa. Plasma cleaning treatment is performed on the ceramic membrane at the working pressure, with a discharge power of 50-300 W and a discharge treatment time of 2-20 min, preferably 100-200 W and 5-10 min.

[0031] During the plasma discharge treatment, oxygen can be excited to form oxygen plasma, mainly including: O· (atomic oxygen radical), O + , O2 + , O3, metastable O2, and free electrons, etc. Oxygen plasma can effectively remove organic contaminants on the surface of the ceramic membrane, exposing the metal-oxygen bond active sites on the surface of the material. After the contaminants are removed, the active oxygen species, mainly atomic oxygen (O·), will react with the oxygen vacancies or metal coordination sites on the surface of the ceramic membrane, generating a large number of surface hydroxyl groups (–OH) in the presence of water molecules or environmental water vapor, thereby grafting the hydroxyl groups to the surface of the ceramic membrane, improving the polarity and hydrophilicity of the ceramic membrane; at the same time, atomic oxygen can also fill the oxygen vacancies on the surface of the ceramic membrane, increasing the degree of oxidation of the surface, increasing the surface dipole moment, and further improving the hydrophilicity of the ceramic membrane; in addition, active oxygen can form a slight nano-scale etching on the ceramic surface, forming a uniform micro-nano structure, which is beneficial to the spreading of water molecules without significantly increasing the risk of contaminant adhesion, thereby further improving the wettability and anti-pollution performance of the membrane surface.

[0032] Plasma discharge cleaning of the ceramic membrane can significantly reduce the water contact angle of the ceramic membrane surface (from about 65° to 10-20°), increase the surface energy, and make it easy for the water film to form a continuous wetting layer on the membrane surface. The wetting layer can inhibit the direct contact of sludge, colloid and microorganisms with the membrane surface, prevent microorganisms, colloidal substances or suspended solids from adhering to the surface of the ceramic membrane, block the filtration pores of the ceramic membrane, and reduce the filtration efficiency.

[0033] In the present application, in addition to opening the chemical bonds on the surface of the ceramic membrane by plasma discharge treatment, exposing active sites, and performing grafting treatment on the surface of the ceramic membrane, an anti-pollution treatment is also provided. Preferably, the step S2 can include: placing the modified ceramic membrane in a multi-walled carbon nanotube solution to uniformly coat the surface of the modified ceramic membrane with multi-walled carbon nanotubes; preferably, the concentration of multi-walled carbon nanotubes in the multi-walled carbon nanotube solution is 0.1 g / L ~ 2 g / L, preferably 0.5 g / L ~ 1 g / L. The above-mentioned "placing in a multi-walled carbon nanotube solution" can be realized in various ways to uniformly coat the surface of the ceramic membrane with multi-walled carbon nanotubes. For example: the ceramic membrane can be soaked in a multi-walled carbon nanotube solution. The soaking treatment time can be determined according to the coating effect of the multi-walled carbon nanotubes, and preferably the above-mentioned soaking is carried out in a dip coating tank, the soaking treatment time is 5 ~ 10 min, and the liquid level of the multi-walled carbon nanotubes can be set as needed to completely cover the ceramic membrane. In order to ensure that the multi-walled carbon nanotubes in the coating are uniformly dispersed during the dip coating process, a stirrer can be used for stirring.

[0034] The above-mentioned multi-walled carbon nanotube solution is prepared by uniformly mixing multi-walled carbon nanotubes, a dispersing agent and a solvent; preferably, during preparation, the multi-walled carbon nanotubes, the dispersing agent and the solvent are stirred uniformly with a stirrer to ensure that the multi-walled carbon nanotubes and the dispersing agent are uniformly mixed, and then ultrasonic treatment is carried out, the treatment time can be 30 ~ 60 min, which can be determined according to the concentration and uniformity of the suspension, and the ultrasonic frequency is 20 ~ 40 kHz to efficiently disperse the multi-walled carbon nanotubes; preferably, the suspension is subjected to intermittent ultrasonic treatment to prevent the multi-walled carbon nanotube solution from overheating, for example, ultrasonic treatment can be carried out for 10 ~ 15 min, and then paused for 1 ~ 2 min.

[0035] After ultrasonic treatment, it is observed with the naked eye whether there are undispersed multi-walled carbon nanotubes in the suspension. If the suspension is uniform and there is no precipitation, it indicates that the dispersion effect is good; if the dispersion is uneven, ultrasonic treatment can be continued until the suspension is uniformly mixed.

[0036] The dispersing agent can be one of SDS, PVP or Triton X-100, which can be selected according to actual needs, for example, if SDS is used, the concentration of the dispersing agent can be 0.5 ~ 5 g / L, preferably 1 g / L ~ 2 g / L; if PVP or Triton X-100 is used, the concentration of the dispersing agent can be 1.0 g / L ~ 10 g / L, preferably 1 g / L ~ 5 g / L; the solvent is one of water or ethanol, preferably water, and the above-mentioned water is deionized water; if an organic auxiliary agent is used in the suspension, a small amount of ethanol can be added.

[0037] Preferably, in order to uniformly coat the multi-walled carbon nanotubes on the surface of the ceramic membrane, the step S2 comprises: drying and curing the modified ceramic membrane coated with the multi-walled carbon nanotubes; the drying temperature is 50-60℃, and the time is 1-2h; the curing temperature is 200-400℃, and the time is 1-2h.

[0038] The combination between the multi-walled carbon nanotubes and the modified ceramic membrane after plasma treatment is mainly physical combination, including van der Waals force, electrostatic interaction and mechanical embedding effect formed by surface microstructure; at the same time, due to the fact that the ceramic membrane surface is rich in polar functional groups such as hydroxyl groups, the multi-walled carbon nanotube surface can also introduce certain oxygen-containing functional groups under the action of ultrasonic dispersion and dispersant, mainly including hydroxyl groups, and possibly containing a small amount of carbonyl or carboxyl groups, so as to form hydrogen bonds and other non-covalent chemical interactions between the interface of the ceramic membrane and the multi-walled carbon nanotubes; in the subsequent drying and heat treatment curing process, the above interface interaction is further stabilized, so as to realize the firm coating of the multi-walled carbon nanotubes on the surface of the ceramic membrane.

[0039] According to a second aspect of the present application, a kind of anti-pollution ceramic membrane prepared by surface treatment method is provided.

[0040] According to a third aspect of the present application, a kind of anti-pollution ceramic membrane is applied in sewage treatment.

[0041] According to a fourth aspect of the present application, a kind of sewage treatment method is provided, which is that sewage is filtered by anti-pollution ceramic membrane to obtain concentrated sludge and membrane effluent, and the anti-pollution ceramic membrane is the anti-pollution ceramic membrane described above; preferably, the sewage treatment method is that the sewage and / or membrane effluent is filtered by single-stage or multi-stage ceramic membrane; the sewage treatment method further comprises harmless treatment of the concentrated sludge.

[0042] The ceramic membrane in the present application is a tubular ceramic membrane with honeycomb shape and multiple channels, which has a cylindrical shell outside and multiple slender channels inside, and the inner wall of each channel forms a filtration layer of nanofiltration ceramic membrane, and the outer wall is a ceramic support layer. When sewage is filtered, it contacts the filtration layer of the inner wall of the channel, and after being selectively intercepted by the membrane layer, solid-liquid separation is realized. Suspended solids, particles and organic matter are intercepted on the surface of the anti-pollution ceramic membrane, while water molecules can pass through the micropores or molecular pores of the anti-pollution ceramic membrane to realize solid-liquid separation. Thus, the anti-pollution ceramic membrane can effectively remove suspended solids, particles and organic matter in water, improve water purification effect, and ensure stable operation of sewage treatment.

[0043] In the present application, domestic sewage filtration is taken as an example.

[0044] As Figure 3As shown, according to a preferred embodiment of this application, domestic sewage is filtered in a single stage, specifically, the sewage is filtered through an anti-fouling ceramic membrane and the effluent is directly reused; the concentrated sludge after the anti-fouling ceramic membrane filtration is carbonized for utilization. like Figure 4 As shown, according to the second embodiment of this application, domestic sewage is filtered in a multi-stage manner. Specifically, after the domestic sewage is filtered through an antifouling ceramic membrane, the first membrane effluent is directly reused; the concentrated liquid from the first membrane filtration is filtered again through an antifouling ceramic membrane, and the second membrane effluent is directly reused, while the concentrated liquid from the second membrane filtration is used for sludge carbonization. The concentrated liquid from the membrane filtration can be further filtered through an antifouling ceramic membrane or directly used for sludge carbonization, depending on the actual situation (e.g., the water content of the concentrated liquid).

[0045] Over time, impurities and particles accumulate on the surface of antifouling ceramic membranes, reducing their permeability and thus affecting filtration efficiency. To remove these impurities and particles, pressure can be applied to the membrane surface, or water can be flushed in the opposite direction to the inlet water flow.

[0046] To prevent large particles and contaminants in domestic sewage from affecting the treatment effect of the antifouling ceramic membrane, it is preferable to pretreat the sewage before filtration to remove large particles and prevent damage to the membrane surface. For example, aerated grit chambers and cyclone grit chambers can be used to remove sand particles with an effective diameter ≥0.1mm. To remove smaller particles and organic matter, preventing clogging of the membrane's micropores and reducing filtration efficiency, mesh or precision filters can be installed. The mesh uses a combination of 1-2mm fine grids and 0.5mm fine mesh screens for mechanical filtration, removing small leaves, broken plastics, fibers, and other debris from the domestic sewage. Precision filters physically intercept impurities through filter cartridges or bags, removing fine suspended solids, flocculent matter, colloids, etc., ranging from 50 to 100 microns.

[0047] The concentrated sludge after filtering domestic sewage contains abundant nitrogen, phosphorus, and other substances, as well as large amounts of water, pathogenic microorganisms, and parasites. To achieve the harmlessness, volume reduction, and resource utilization of the concentrated sludge, the sewage treatment method preferably further includes harmless treatment of the concentrated sludge. The aforementioned harmless sludge treatment includes: sludge thickening to separate water and solid matter from the sludge; sludge drying to completely evaporate the water in the sludge; and sludge carbonization to decompose the organic matter in the sludge.

[0048] In order to separate the solid and liquid in the ceramic membrane filtrate as much as possible, the above sludge concentration can include at least one of gravity concentration and centrifugal concentration. In this application, in order to ensure the effect of solid-liquid separation, the ceramic membrane filtrate is first subjected to gravity concentration and then subjected to centrifugal concentration.

[0049] The gravity concentration in this application adopts a circular sedimentation tank. Due to its symmetry, the circular sedimentation tank can provide a uniform sedimentation environment. The liquid flow is distributed radially in the circular tank, and the flow rate is relatively uniform, which helps uniform sedimentation and reduces the occurrence of short flow and vortex, thereby improving the sedimentation efficiency. The depth of the above-mentioned circular sedimentation tank is 3-6 m, and a deeper sedimentation tank can reduce disturbance, avoid particle floating, and improve sedimentation efficiency. The surface load is usually valued at 0.6-1.2 m 3 / m 2 ·h, the design of the surface area should ensure uniform distribution of water flow, avoid local flow rate being too large or too small, and thus affect the sedimentation effect. By reasonably designing the depth and surface area of the sedimentation tank, combined with the characteristics of particle size and concentration, and controlling the appropriate standing time, the sedimentation effect of solid particles can be effectively improved, and the efficient operation of the sedimentation tank can be ensured. An overflow port is provided at the top of the circular sedimentation tank to ensure that the supernatant discharged is clear. The supernatant can be returned to the front end of the membrane treatment for further treatment. The sludge discharge pipe is arranged at the bottom center or slightly offset from the center of the sedimentation tank, and is made of corrosion-resistant materials such as PVC and stainless steel to ensure long-term use without corrosion during sludge treatment. The above-mentioned sedimentation tank can be a single tank, and is preferably a plurality of parallelly connected sedimentation tanks to improve the treatment capacity and operational flexibility.

[0050] The sludge after gravity concentration is transported to the feed inlet of the centrifuge through the sludge pump and the conveying pipeline for centrifugal concentration; the sludge enters the centrifuge, and the above-mentioned centrifuge can be in an appropriate form, for example, the sludge after gravity concentration can be transported to a horizontal screw centrifuge at a flow rate of 5-15 m³ / h through the sludge pump, and the linear velocity of the conveying pipeline is preferably maintained at 1.5-3.0 m / s to ensure stable transportation and prevent sludge deposition. Preferably, according to the properties of the sludge, a flocculating agent can be added to improve the dewaterability of the sludge. When the sludge particle size is small, the colloidal content is high, the solid content is low, the electrification is strong, or the sludge runs, the solid-liquid separation is poor, the cake moisture content is high, etc. during the centrifugal dewatering process, a flocculating agent is preferably added to the sludge to improve its coagulation and dewatering performance.

[0051] The rotation speed of the centrifuge is 1000-6000 r / min, and the specific rotation speed needs to be determined according to the properties of the sludge and the required separation effect. A screw conveyor is arranged in the centrifuge for pushing the solid sludge out, and the water content in the solid sludge is 60%-80%; the separated centrifugal liquid is discharged through a liquid discharge port of the centrifuge, and the flow rate and quality of the centrifugal liquid can be adjusted and controlled by adjusting the parameters of the centrifuge to reduce the solid particles in the liquid as much as possible.

[0052] The sludge drying includes preliminary drying and deep drying. The preliminary drying is to preliminarily dry the sludge by a heat source such as hot air, steam or electric heating in a drying device to further reduce the water content. The deep drying is to fully contact the sludge with a heat medium in the drying device, and the water in the sludge is continuously evaporated by convection, conduction and radiation and the like. The temperature of the deep drying is 100-200°C. After the drying, the water content in the sludge is 10%-20%.

[0053] The sludge carbonization includes pyrolysis reaction and carbonization reaction. The pyrolysis reaction is to heat the sludge to 300-600°C in an oxygen-deficient or oxygen-free environment, and the organic matter begins to decompose to generate volatile gas, liquid tar and solid residue. The oxygen content in the carbonization furnace is usually controlled at a very low level to ensure that the pyrolysis reaction mainly occurs rather than the oxidation reaction. Before the sludge enters the carbonization furnace, the carbonization furnace needs to be preheated to reach the carbonization temperature. After the sludge enters the carbonization furnace, the sludge is gradually heated to reach the reaction temperature. When the pyrolysis reaction temperature reaches 100-200°C, the water in the sludge evaporates. When the pyrolysis reaction temperature reaches 200-300°C, the organic matter begins to pyrolyze to generate volatile organic matter, tar and preliminary carbonization products. When the pyrolysis reaction temperature reaches 300-600°C, the organic matter is largely decomposed to generate volatile gas (such as CO, CO2, CH4, H2, etc.), liquid tar and solid residue (biochar).

[0054] The carbonization reaction is to continue heating the solid residue after the pyrolysis reaction to increase the temperature to 600-900°C, and the specific reaction temperature needs to be adjusted according to the properties of the sludge and the expected product. When the carbonization temperature is 600-700°C, the organic matter in the solid residue continues to decompose to generate more gas (such as CO, CO2, CH4, H2, etc.) and liquid tar, and the residual matter begins to be converted into biochar. When the carbonization temperature reaches 700-900°C, the organic components in the solid residue are decomposed to generate volatile gas and liquid, and the remaining solid matter is gradually converted into biochar with high carbon content. When the water content of the sludge is high, the organic matter (volatile matter) content is large, the inorganic particle proportion is high or the heavy metal content is high, it is preferred to increase the carbonization temperature to 750-900°C to ensure complete pyrolysis and realize heavy metal stabilization.

[0055] If the sludge has a high solid content, a low organic matter content, or is intended to be used as a soil conditioner with a well-developed pore structure, the carbonization can be carried out at 600-750°C.

[0056] Therefore, the present application selects 600-900°C as the preferred carbonization temperature range to meet the needs of different sludge properties and different end products.

[0057] During the carbonization process, the temperature in the carbonization furnace needs to be precisely controlled to ensure that the carbonization reaction takes place within the optimal temperature range. The pressure in the carbonization furnace is maintained at a negative pressure state to prevent external air from entering. The gas composition in the carbonization furnace is monitored in real time, and the reaction parameters are adjusted to ensure efficient carbonization reaction and product stability.

[0058] Preferably, during the above-mentioned carbonization reaction process, the heat in the high-temperature gas can be recovered through a heat exchanger to preheat the sludge or supply other heat treatment equipment, improving the overall energy efficiency. The heat not directly utilized is recovered through a waste heat boiler or other equipment for power generation or heating, further improving energy utilization efficiency.

[0059] The gas products of the carbonization reaction need to be treated through a condenser and a purification device to recover combustible gas, which is used for power generation or heating after purification, and non-combustible gas is directly discharged. Liquid tar is collected through a condenser for further refining and processing to extract valuable chemical components or used as fuel. The solid product (biochar) is discharged from the bottom of the carbonization furnace through a discharge system for cooling, storage, or further processing and utilization. The tail gas is treated through combustion or other purification equipment to ensure that the emissions meet environmental standards and reduce environmental pollution.

[0060] To further improve the resource utilization of sludge, the biochar can be dried and granulated for use as a soil conditioner or low fuel. A granulation device such as a granulator or tablet press is used to granulate the dried biochar. During the granulation process, the carbonized material is pressed into uniform size and density particles through appropriate pressure and shape molds. The granulated carbonized material is applied to farmland, gardening, or landscaping projects as a soil conditioner. The carbonized material can improve soil water retention, aeration, and fertility, promote crop growth, reduce the use of chemical fertilizers, improve the ecological environment, and achieve sustainable agricultural development.

[0061] The surface treatment method of the ceramic membrane in the present application will be described below in conjunction with examples.

[0062] 1. Example Example 1 A1. Place the ceramic membrane to be treated in an ultrasonic cleaner and perform ultrasonic cleaning; A2. Dry the ceramic membrane cleaned in step A1 in an oven at 65°C for 1h; A3. Put the ceramic membrane in step A2 into a plasma treatment device, introduce oxygen into the plasma treatment device, the gas flow is 10 sccm, the internal pressure of the device is 10 Pa, set the discharge power to 50 W, and the treatment time is 2 min, so that the modified ceramic membrane is obtained; A4. Prepare a suspension of multi-walled carbon nanotubes, a dispersing agent and a solvent to obtain a coating. In the above suspension, the concentration of multi-walled carbon nanotubes is 0.1 g / L, and the concentration of the dispersing agent is 0.5 g / L. The dispersing agent is SDS; A5. Soak the ceramic membrane in the coating prepared in step A4 for 5 min, and slowly take out the ceramic membrane from the coating while keeping the speed stable; A6. Place the ceramic membrane coated with the coating on a drying rack to ensure uniform drying of the surface; A7. Place the ceramic membrane coated with the coating in step A6 in an oven for low-temperature drying at 50°C for 1 h; A8. Treat the ceramic membrane subjected to low-temperature drying in step A7 in a high-temperature furnace at 200°C for 1 h to obtain a pollution-resistant ceramic membrane.

[0063] Example 2 The surface treatment method in Example 1 is used, wherein: A3. The gas flow is 150 sccm, the internal pressure of the device is 55 Pa, the discharge power is set to 175 W, and the treatment time is 11 min; A4. The concentration of multi-walled carbon nanotubes is 1 g / L, and the concentration of the dispersing agent is 5 g / L. The dispersing agent is SDS; A5. Soak the ceramic membrane in the coating prepared in step A4 for 7.5 min; A7. Low-temperature drying at 55°C for 1.5 h; A8. Treat the ceramic membrane subjected to low-temperature drying in step A7 in a high-temperature furnace at 300°C for 1.5 h to obtain a pollution-resistant ceramic membrane.

[0064] Example 3 The surface treatment method in Example 1 is used, wherein: A3. The gas flow is 300 sccm, the internal pressure of the device is 100 Pa, the discharge power is set to 300 W, and the treatment time is 20 min; A4. The concentration of multi-walled carbon nanotubes is 1 g / L, and the concentration of the dispersing agent is 5 g / L. The dispersing agent is SDS; A5. Soak the ceramic membrane in the coating prepared in step A4 for 7.5 min; A7. Low-temperature drying at 55°C for 1.5 h; A8. The ceramic membrane dried at low temperature in step A7 was treated in a high temperature furnace at 300°C for 1.5h to obtain a pollution resistant ceramic membrane.

[0065] Example 4 The surface treatment method in Example 1 was used, wherein: A3. The gas flow rate was 30sccm, the internal pressure of the equipment was 30Pa, the discharge power was set to 100W, and the treatment time was 5min; A4. The concentration of multi-walled carbon nanotubes was 0.5 g / L, and the concentration of dispersant was 1 g / L, and the dispersant was SDS.

[0066] Example 5 The surface treatment method in Example 1 was used, wherein: A3. The gas flow rate was 150sccm, the internal pressure of the equipment was 50Pa, the discharge power was set to 200W, and the treatment time was 10min; A4. The concentration of multi-walled carbon nanotubes was 1 g / L, and the concentration of dispersant was 5 g / L, and the dispersant was PVP or Triton X-100.

[0067] Example 6 The surface treatment method in Example 1 was used, wherein: A3. The gas flow rate was 90sccm, the internal pressure of the equipment was 40Pa, the discharge power was set to 150W, and the treatment time was 7.5min; A4. The concentration of multi-walled carbon nanotubes was 0.75 g / L, and the concentration of dispersant was 3 g / L, and the dispersant was PVP or Triton X-100.

[0068] Example 7 The surface treatment method in Example 3 was used, wherein, A4. The concentration of multi-walled carbon nanotubes was 1 g / L, and the concentration of dispersant was 2 g / L, and the dispersant was SDS.

[0069] Example 8 The preparation method of pollution resistant ceramic membrane in Example 2 was used, wherein, A4. The concentration of multi-walled carbon nanotubes was 0.75 g / L, and the concentration of dispersant was 1.5 g / L, and the dispersant was SDS.

[0070] Comparative Example 1 A nanofiltration ceramic membrane without any treatment was used.

[0071] Comparative Example 2 The surface treatment method in Example was used, wherein steps A4-A8 were not included.

[0072] 2. Test method The ceramic membranes in the examples and comparative examples were used.

[0073] The influent water quality was COD: 480 mg / L, TSS: 320 mg / L, total nitrogen (TN): 67 mg / L, and total phosphorus (TP): 6.5 mg / L.

[0074] The sewage treatment process was that the sewage passed through a fine mesh screen (0.5 mm) → a ceramic membrane → effluent in sequence. Operation mode: external pressure type (high-pressure pump driven), transmembrane pressure (TMP) 0.6 MPa, and working temperature 20±2℃; Circulation speed: 0.5 m / s; Recovery rate: 80% permeation rate and 20% concentrated liquid recovery.

[0075] 3. Experimental results 3.1 Surface properties of ceramic membranes and membrane flux The anti-fouling ceramic membranes prepared in Examples 1-5 and Examples 7 and 8 differ in plasma activation intensity, multi-walled carbon nanotube loading, and dispersion system, and the membrane surface hydrophilicity and anti-fouling performance thereof are all better than those of the untreated ceramic membrane (Comparative Example 1) and the modified ceramic membrane treated only by plasma (Comparative Example 2), but in terms of comprehensive flux retention rate and regeneration performance, Example 6 exhibits the best comprehensive performance. Example 6 achieves the best match among plasma activation intensity, multi-walled carbon nanotube loading, and dispersion system, and the hydrophilicity, flux retention rate, anti-fouling performance, and regeneration performance thereof are all significantly better than those of other examples, so Example 6 is taken as an example in this application.

[0076] The ceramic membrane surface is hydrophilic if the contact angle between the surface and water is less than 90°.

[0077] Table 1. Surface properties of ceramic membranes and membrane flux As shown in Table 1, the hydrophilicity of the anti-fouling ceramic membrane in Example 6 and the modified ceramic membrane in Comparative Example 2 is higher, both higher than that of the ceramic membrane in Comparative Example 1 which is not treated in any way; the 72h flux retention rate and flux recovery rate after in-situ regeneration of the anti-fouling ceramic in Example 6 are both significantly higher than those of Comparative Examples 1 and 2, indicating that the anti-fouling ceramic membrane prepared in this application can effectively avoid the adhesion of impurities in sewage.

[0078] 3.2 Effluent water quality removal rate of ceramic membranes Table 2. Effluent water quality removal rate of ceramic membranes From Table 2, it can be seen that the anti-pollution ceramic membrane prepared in the present application can effectively filter COD, total nitrogen (TN) and total phosphorus (TP) in sewage.

[0079] The preferred embodiments of the present application are described in detail above, but the present application is not limited to the specific details of the above-described embodiments. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, and these simple modifications all belong to the protection scope of the present application.

[0080] In addition, it should be noted that each specific technical feature described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, various possible combinations are not described again in the present application.

[0081] In addition, various different embodiments of the present application can also be combined in any manner, as long as they do not deviate from the idea of the present application, and they should also be considered as disclosed content of the present application.

Claims

1. A surface treatment method for ceramic films, characterized in that, The surface treatment method includes: S1. Modify the surface of the material to obtain a hydrophilic modified ceramic film; S2. The surface of the modified ceramic membrane is subjected to anti-fouling treatment to obtain an anti-fouling ceramic membrane; The ceramic membrane is a nanofiltration ceramic membrane with a pore size of 1nm to 5nm.

2. The surface treatment method for ceramic films according to claim 1, characterized in that, Step S1 includes: S11. The ceramic membrane to be treated is subjected to plasma cleaning to remove contaminants on the surface of the ceramic membrane and expose the active sites on the surface of the ceramic membrane; S12. Grafting treatment is performed on the cleaned ceramic membrane.

3. The surface treatment method for ceramic films according to claim 2, characterized in that, Steps S11 and S12 include: performing plasma cleaning on the ceramic membrane in a first gas atmosphere, wherein the first gas is one or more of oxygen, hydrogen, and an inert gas, and preferably, the inert gas is argon and nitrogen.

4. The surface treatment method for ceramic films according to claim 3, characterized in that, The flow rate of the first gas is 10 sccm to 300 sccm, preferably 30 sccm to 150 sccm; the working gas pressure is 10 Pa to 100 Pa, preferably 30 Pa to 50 Pa.

5. The surface treatment method for the ceramic film according to claim 3, characterized in that, The discharge power of the plasma cleaning process is 50W~300W, and the discharge time is 2min~20min. Preferably, the discharge power is 100W~200W, and the cleaning time is 5min~10min.

6. The surface treatment method for a ceramic film according to claim 1, characterized in that, Step S2 includes: The modified ceramic film is placed in a solution of multi-walled carbon nanotubes, so that the surface of the modified ceramic film is uniformly coated with multi-walled carbon nanotubes. Preferably, the concentration of multi-walled carbon nanotubes in the multi-walled carbon nanotube solution is 0.1 g / L to 2 g / L, more preferably 0.5 g / L to 1 g / L; the treatment time is 5 to 10 min.

7. The surface treatment method for a ceramic film according to claim 6, characterized in that, Step S2 includes: The modified ceramic film coated with multi-walled carbon nanotubes was dried and cured. The drying temperature is 50~60℃, and the time is 1~2 hours; The curing temperature is 200~400℃, and the time is 1~2h.

8. The anti-fouling ceramic film prepared by the surface treatment method according to any one of claims 1-7.

9. The application of the antifouling ceramic membrane according to any one of claims 1-7 and 8 in wastewater treatment.

10. A wastewater treatment method, characterized in that, The method involves filtering wastewater through an antifouling ceramic membrane to obtain concentrated sludge and membrane effluent, wherein the antifouling ceramic membrane is the antifouling ceramic membrane described in claim 8. Preferably, the wastewater treatment method involves filtering the wastewater and / or membrane effluent through a single-stage or multi-stage ceramic membrane. The wastewater treatment method further includes harmlessly treating the concentrated sludge.

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