A hydrophilic polyurethane carrier for electro-enhanced microbial treatment of industrial wastewater, method of preparation and use

Abstract

This invention provides a hydrophilic polyurethane carrier for electro-enhanced microbial treatment of industrial wastewater, its preparation method, and its application. A premixed system A is prepared by weight: 100 parts polyether triol, 0.2-0.4 parts N-methyldiethanolamine, 0.8-1.2 parts dibutyltin dilaurate, 0.8-1.2 parts organosilicon surfactant, 3-5 parts water, 2-4 parts dichloromethane, and 7-9 parts pore-opening agent. A premixed system B is prepared by weight: 17-23 parts hydrophilic agent and 57-63 parts toluene diisocyanate 2,4 isomer. A and B are placed in a reactor, and then 23-27 parts of liquid sodium polyacrylate with an isocyanate index of 1.0-1.2 and 3-5 parts graphene powder are added. The mixture is stirred to allow for rapid reaction, followed by foaming and curing treatments. The mixture is then cut, treated successively with sodium carbonate solution and acetic acid solution, washed, and dried to obtain the final carrier. The resulting carrier exhibits good performance and is particularly suitable for treating coking wastewater.

Description

Technical Field

[0001] This invention belongs to the field of biological treatment technology of water, wastewater or sewage in the IPC classification table CO2F3, specifically relating to a hydrophilic polyurethane carrier for electro-enhanced microbial treatment of industrial wastewater, its preparation method and application. Background Technology

[0002] The large-scale generation of coking wastewater has posed a serious threat to the ecological environment and human health. Because coking wastewater contains a large amount of toxic and harmful substances, it slows down the treatment efficiency by inhibiting the metabolism of microorganisms. Conventional biological treatment methods are insufficient to achieve efficient treatment of coking wastewater, leading to the development of a series of novel coking wastewater treatment processes. Although immobilized biological technology can stimulate microorganisms to secrete more extracellular polymers to enhance their resistance to the toxicity of coking wastewater, it still falls short of meeting the requirements for efficient treatment. This has resulted in a new electro-enhanced microbial treatment process for coking wastewater.

[0003] Electro-enhanced immobilized microbial technology can significantly reduce the toxic effects of coking wastewater on microorganisms by stimulating them with electric current, thereby significantly improving the treatment effect of coking wastewater. Therefore, it has broad application prospects and practical value. However, currently available carriers, including zeolite, volcanic rock, and K3 rings, have relatively limited functions and can only be used as activated sludge biofilm carriers for conventional domestic sewage treatment. Many of these carriers have poor biofilm formation effects and require longer start-up times to complete the biofilm formation process. Furthermore, these carriers have not been specifically designed for electro-enhanced treatment, resulting in easy detachment of the biofilm formed under electro-enhanced action. Moreover, the manufacturing process of conventional polyurethane carriers is cumbersome, usually requiring additional steps to graft hydrophilic chemical groups after production to modify the conventional polyurethane carrier, which increases the process flow and cost of producing hydrophilic polyurethane carriers. In summary, current carriers used in novel electro-enhanced coking wastewater treatment processes are still mainly conventional carriers. These carriers often have problems such as poor conductivity, low biofilm formation efficiency, poor microbial adsorption, and easy biofilm detachment, making them difficult to effectively apply to electro-enhanced immobilized microbial technology for treating coking wastewater.

[0004] To this end, the present invention develops a novel hydrophilic polyurethane carrier and its preparation method, and effectively applies it to the optimization of electro-enhanced immobilized microbial treatment of coking wastewater. Summary of the Invention

[0005] The purpose of this application is to provide a hydrophilic polyurethane carrier for electro-enhanced microbial treatment of industrial wastewater, its preparation method, and its application, so as to at least solve one of the problems in the prior art, such as the poor performance of hydrophilic polyurethane carriers, which are difficult to apply to electro-enhanced microbial treatment of coking wastewater.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing a hydrophilic polyurethane carrier for electro-enhanced microbial treatment of industrial wastewater, comprising the following steps: S1. Prepare premixed system A according to the following mass ratio: 100 parts polyether triol, 0.2-0.4 parts N-methyldiethanolamine, 0.8-1.2 parts dibutyltin dilaurate, 0.8-1.2 parts organosilicon surfactant, 3-5 parts water, 2-4 parts dichloromethane, and 7-9 parts pore opener; S2. Prepare premixed system B according to the following mass ratio: 17-23 parts hydrophilic agent, 57-63 parts toluene diisocyanate 2,4 isomer; S3. After placing the premixed system A and B into the reactor, add 23-27 parts of liquid sodium polyacrylate with an isocyanate index R of 1.0-1.2 and 3-5 parts of graphene powder. Stir to make the whole system react quickly, and then pour it into the foaming box for foaming and curing treatment to obtain the modified foam. S4. The modified foam is cut into blocks, and the blocks are post-treated with sodium carbonate solution and acetic acid solution. After washing and drying, the modified hydrophilic polyurethane carrier is obtained.

[0007] In the above-mentioned method for preparing a hydrophilic polyurethane carrier for electro-enhanced microbial treatment of industrial wastewater, as a preferred embodiment, in step S1, the molecular weight of the polyether triol is 3000-5000, preferably polyether triol MN3050.

[0008] In the above-mentioned method for preparing a hydrophilic polyurethane carrier for electro-enhanced microbial treatment of industrial wastewater, as a preferred embodiment, in step S1, the pore-opening agent is at least one of ZL K-360, ZL Y-1900 and GSY-28.

[0009] In a preferred embodiment of the above-mentioned method for preparing a hydrophilic polyurethane carrier for electro-enhanced microbial treatment of industrial wastewater, the hydrophilic agent in step S2 is a polyether-modified copolymer surfactant; further, the hydrophilic agent is at least one of ZL-480 and Xt-9093.

[0010] In the above-mentioned method for preparing a hydrophilic polyurethane carrier for electro-enhanced microbial treatment of industrial wastewater, as a preferred embodiment, in step S1, a premixed system A is prepared according to the following mass ratio: 100 parts of polyether triol, 0.3 parts of N-methyldiethanolamine, 1 part of dibutyltin dilaurate, 1 part of organosilicon surfactant, 4 parts of water, 3 parts of dichloromethane, and 8 parts of pore-opening agent.

[0011] In a preferred embodiment of the above-mentioned method for preparing a hydrophilic polyurethane carrier for electro-enhanced microbial treatment of industrial wastewater, in step S2, a premixed system B is prepared according to the following mass ratio: 20 parts hydrophilic agent and 60 parts toluene diisocyanate 2,4 isomer.

[0012] In a preferred embodiment of the above-mentioned method for preparing a hydrophilic polyurethane carrier for electro-enhanced microbial treatment of industrial wastewater, step S3 involves adding 25 parts of liquid sodium polyacrylate with an isocyanate index R of 1.0-1.2 and 4 parts of graphene powder.

[0013] In the above-mentioned method for preparing a hydrophilic polyurethane carrier for electro-enhanced microbial treatment of industrial wastewater, as a preferred embodiment, in step S3, the stirring is carried out at a speed of 150-300 rpm for 8-15 minutes, for example, at a speed of 200 rpm for 10 minutes.

[0014] In the above-mentioned method for preparing a hydrophilic polyurethane carrier for electro-enhanced microbial treatment of industrial wastewater, as a preferred embodiment, in step S3, after the material is poured into the foaming box, it is placed at 30-60°C for 20-30 hours, for example, at 40°C for 24 hours.

[0015] In step S3 and step S4, the post-processing includes: reacting the block foam in a 10% sodium carbonate solution for 5-7 hours, washing with water until neutral, then soaking in a 2% acetic acid solution for 10-15 hours, washing with water until neutral, and drying to obtain the modified hydrophilic polyurethane carrier.

[0016] Secondly, the present invention provides a hydrophilic polyurethane carrier for electro-enhanced microbial treatment of industrial wastewater, which is prepared by the above-described method.

[0017] Thirdly, the present invention provides an application of the above-mentioned novel hydrophilic polyurethane carrier in the electro-enhanced microbial treatment of industrial wastewater. Preferably, the industrial wastewater is coking wastewater; Preferably, the current is 200-300 mA during the processing.

[0018] Compared with the prior art, the solution of this application has the following beneficial effects: 1) In view of the difficulties in the manufacturing and application of carriers for electro-enhanced microbial treatment of coking wastewater, this invention provides a one-step preparation method for a novel polyurethane carrier for electro-enhanced microbial treatment of coking wastewater. The method combines graphene and hydrophilic sodium polyacrylate with the polyurethane carrier, making the carrier simple to manufacture while having multiple functions such as improving conductivity and electron transfer efficiency and increasing pollutant removal efficiency.

[0019] 2) This invention provides a method for preparing a novel polyurethane carrier for electro-enhanced microbial treatment of coking wastewater. First, a hydrophilic agent, liquid sodium polyacrylate, is added to the polyurethane carrier during its preparation. Because sodium polyacrylate has abundant cationic active groups and hydrophilic groups such as hydroxyl groups on its surface, it significantly improves the hydrophilicity of the prepared polyurethane carrier, thereby promoting the interaction between microorganisms and the carrier. This solves the problem of microorganisms easily detaching under the toxicity of coking wastewater, making it difficult to achieve stable effects, and effectively preserves the microorganisms growing on the carrier surface. Simultaneously, graphene is added to the preparation of the hydrophilic polyurethane carrier. The addition of graphene significantly enhances the efficacy of the microorganisms. The substances adsorbed on the graphene surface form a conductive layer, which facilitates electron transfer, enhances the electron transfer process between microorganisms, increases the removal efficiency of pollutants, and can also serve as an electrode material, providing electrons to or accepting electrons from electrode reactants, increasing the overall conductivity within the electro-enhanced microbial system. The filler prepared in this invention is specifically designed based on electro-enhancing properties. Graphene facilitates electron transfer and conducts electricity. Furthermore, during the fabrication of the polyurethane carrier, the addition of sodium polyacrylate acts as a dispersant and compatibilizer for graphene, ensuring its uniform distribution within the carrier. The simultaneous addition of both promotes synergistic effects, facilitating the fabrication of the modified hydrophilic polyurethane carrier. Therefore, the one-step hydrophilic polyurethane carrier prepared in this invention can significantly optimize the performance of electro-enhanced microbial treatment of coking wastewater. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating a preferred embodiment of the preparation method of a novel hydrophilic polyurethane for electro-enhanced microbial treatment of coking wastewater according to this application.

[0021] Figure 2 This is an electron microscope scanning image of the hydrophilic polyurethane carrier obtained in Example 1 of this application.

[0022] Figure 3 The image shows the contact angle test results of the hydrophilic polyurethane carrier obtained in Example 1 of this application.

[0023] Figure 4 This is a scanning electron microscope image of the hydrophilic polyurethane carrier obtained in Comparative Example 1 of this application.

[0024] Figure 5 The image shows the contact angle test results of the hydrophilic polyurethane carrier obtained in Comparative Example 1 of this application.

[0025] Figure 6 The image shows the contact angle test results of the hydrophilic polyurethane carrier obtained in Comparative Example 2 of this application.

[0026] Figure 7 The image shows the contact angle test results of the hydrophilic polyurethane carrier obtained in Comparative Example 3 of this application.

[0027] Figure 8 The application example 1 of this application shows the performance of different polyurethane carriers in the electro-enhanced microbial treatment of coking wastewater; wherein, (a) shows the change in ammonia nitrogen concentration; (b) shows the change in nitrite nitrogen concentration; (c) shows the change in nitrate nitrogen concentration; (d) shows the change in ammonia oxidation efficiency and COD removal efficiency; and (e) shows the MLSS and MLVSS on different carriers.

[0028] Figure 9 To illustrate the performance of different polyurethane carriers in electro-enhanced microbial treatment of coking wastewater in Application Example 2 of this application; wherein, (a) shows the change in ammonia nitrogen concentration; (b) shows the change in nitrite nitrogen concentration; (c) shows the change in nitrate nitrogen concentration; (d) shows the change in ammonia oxidation efficiency and COD removal efficiency; and (e) shows the MLSS and MLVSS on different carriers.

[0029] Figure 10 The application embodiment 3 of this application illustrates MLSS and MLVSS on different carriers, as well as MLVSS / MLSS.

[0030] Figure 11 The application example 4 of this application shows the performance of different polyurethane carriers in the electro-enhanced microbial treatment of coking wastewater; wherein, (a) shows the change in ammonia nitrogen concentration; and (b) shows the change in COD removal efficiency. Detailed Implementation

[0031] This application provides a specific embodiment of a method for preparing a hydrophilic polyurethane carrier for electro-enhanced microbial treatment of industrial wastewater, comprising the following steps: S1. Preparation of premixed system A: Prepare premixed system A according to the following mass ratio formula.

[0032]

[0033] In this process, polyether triol is used as a raw material for the gelation reaction. It undergoes an exothermic reaction with the isocyanate groups in the premixed system B described below to generate polyurethane. The molecular weight of the polyether triol is approximately 3000-5000, preferably polyether triol MN3050.

[0034] Water is used as a foaming agent in the reaction, reacting with isocyanates in premixed system B below to generate carbon dioxide gas, forming bubbles in the polymer. The more water there is, the more carbon dioxide gas is generated, and the lower the density of the resulting foam. Additionally, water can also react with isocyanates to form urea groups, urethane groups, and biuret groups in the polymer molecules.

[0035] To accelerate the two reactions mentioned above, N-methyldiethanolamine and dibutyltin dilaurate can catalyze the reactions, speeding up the process and contributing to the formation of the polyurethane carrier skeleton and foam.

[0036] Dichloromethane, as an auxiliary foaming agent, absorbs the heat generated during the reaction process and volatilizes, which helps to form bubbles. In addition, the addition of dichloromethane can make polyurethane foam softer.

[0037] Cell-opening agents can control the size of the pores in polyurethane foam, thereby achieving the purpose of water absorption and sedimentation. Adding too much can cause the polyurethane foam to crack, crumble, and reduce its mechanical strength, while adding too little will result in polyurethane foam with excessively small pores. Examples of cell-opening agents include at least one of the following: ZL K-360 from Changzhou Zhuolian Zhichuang Polymer Materials Technology Co., Ltd., ZL Y-1900 from Dongguan Guangsiyuan Polyurethane Materials Co., Ltd., and GSY-28.

[0038] The main purpose of adding silicone surfactants is to stabilize the formed foam and prevent it from breaking down completely during the later stabilization process.

[0039] S2. Preparation of premixed system B: Prepare premixed system B according to the following mass ratio formula.

[0040]

[0041] Among them, the 2,4 isomer of toluene diisocyanate is the basic raw material for the formation of polyurethane. It can undergo gelation and foaming reactions with polyether triol and water to form a hydrophilic polyurethane carrier.

[0042] The use of hydrophilic agents allows hydrophilic groups, including hydroxyl, carboxyl, and carbonyl groups, to be directly embedded into the prepared hydrophilic polyurethane carrier. The resulting hydrophilic polyurethane carrier exhibits superior hydrophilicity, thereby increasing the stability of the biofilm. The hydrophilic agent is a polyether-modified copolymer surfactant, such as at least one of ZL-480 from Changzhou Zhuolian Zhichuang Polymer Materials Technology Co., Ltd., or Xt-9093 from Xiangtao High-Tech Materials Technology Co., Ltd.

[0043] S3. After placing the premixed systems A and B into the reactor, add 23-27 parts of liquid sodium polyacrylate with an isocyanate index R of 1.0-1.2 and 3-5 parts of graphene powder. Stir to make the whole system react rapidly, and then pour it into the foaming box for foaming and curing treatment and stirring to obtain the modified foam.

[0044] Preferably, the stirring is performed at a speed of 150-300 rpm for 8-15 minutes, for example, at a speed of 200 rpm for 10 minutes.

[0045] Preferably, after the material is poured into the foaming box, it is placed at 30-60°C for 20-30 hours, for example, at 40°C for 24 hours.

[0046] Preferably, 25 parts of liquid sodium polyacrylate with an isocyanate index R of 1.0-1.2 and 4 parts of graphene powder are added.

[0047] During the manufacturing process, the inventors discovered that the addition of highly absorbent cross-linked sodium polyacrylate particles (solid sodium polyacrylate) did not significantly improve the hydrophilicity of the filler. The polyurethane foam produced floated on the surface of the water instead of sinking to the bottom. It is speculated that this is because cross-linked sodium polyacrylate is a solid and is not easily dispersed in the polyether polyol system, resulting in some areas of the polyurethane foam forming hard lumps. The addition of liquid sodium polyacrylate can significantly improve this phenomenon. As a highly efficient hydrophilic agent, dispersant and compatibilizer, liquid sodium polyacrylate can first improve the hydrophilicity of polyurethane foam, thereby enhancing the stability of biofilm formation. Secondly, liquid sodium polyacrylate is a highly efficient dispersant that can help stabilize the dispersion of graphene in the solvent through electrostatic stabilization and steric hindrance: (1) Liquid sodium polyacrylate can ionize in water to form negatively charged polyanions, which can be adsorbed on the surface of graphene sheets. Since the graphene sheets themselves may have some defects or functional groups, they can interact with the negative charge of liquid sodium polyacrylate, thereby preventing the aggregation of graphene sheets through electrostatic repulsion. (2) Liquid sodium polyacrylate molecular chains can form a large spatial configuration in water. These molecular chains can surround graphene sheets, forming steric hindrance and preventing the aggregation between graphene sheets. Furthermore, liquid sodium polyacrylate is a highly efficient compatibilizer that can improve the compatibility of graphene with other polymer matrices by improving interfacial interactions and promoting dispersion: (1) Liquid sodium polyacrylate molecules contain both hydrophilic and hydrophobic parts, which can enable it to interact with both graphene and polymer matrices simultaneously. (2) Liquid sodium polyacrylate can connect graphene sheets to the polymer matrix through the bridging effect of its polymer chains, thereby promoting the dispersion of graphene in the polymer. Through these effects, liquid sodium polyacrylate can effectively improve the dispersibility and compatibility of graphene in polyurethane carriers, thereby enhancing the overall performance of composite materials.

[0048] S4. Cut the foam into blocks (e.g., 2cm×2cm×2cm cubes), then treat the blocks with sodium carbonate solution and acetic acid solution, and after washing and drying, obtain the modified hydrophilic polyurethane carrier.

[0049] Optionally, the post-processing includes: reacting the block foam in a 10% sodium carbonate solution for 5-7 hours, washing with water until neutral, then soaking in a 2% acetic acid solution for 10-15 hours, washing with water until neutral, and drying to obtain a modified hydrophilic polyurethane carrier.

[0050] This application also provides a novel hydrophilic polyurethane carrier, which is prepared using the above-described method.

[0051] This application also provides an application of a novel hydrophilic polyurethane carrier in the electro-enhanced microbial treatment of industrial wastewater.

[0052] Preferably, the industrial wastewater is coking wastewater.

[0053] Preferably, the current is 200-300 mA during the processing.

[0054] The present invention will be further described in detail below through embodiments and comparative examples. The scope of protection of the present invention includes, but is not limited to, the following embodiments.

[0055] For any experimental steps or conditions not specified in the following examples and comparative examples, the procedures or conditions described in the literature in this field can be followed.

[0056] Unless otherwise stated, all reagents and raw materials used in the following examples and comparative examples are commercially available products.

[0057] Example 1 In this embodiment, the process for preparing the novel hydrophilic polyurethane for electro-enhanced microbial treatment of coking wastewater is described below. Figure 1 It includes the following steps: S1. Preparation of premixed system A: Prepare premixed reagent A according to the formula shown in Table 1 below.

[0058] Table 1. Formulation of Premixed Reagent A

[0059] S2. Preparation of premixed system B: Prepare premixed reagent B according to the formula shown in Table 2 below.

[0060] Table 2 Premixed Reagent B Formulation

[0061] S3. After placing the premixed systems A and B prepared in steps 1 and 2 into the reactor, add 250g of liquid sodium polyacrylate (molecular weight 2100, CAS No. 9003-04-7, Shanghai Maclean Biochemical Technology Co., Ltd.) with an isocyanate index of 1.0-1.2 and 40g of graphene powder (particle size 7-2μm, CAS No. 7782-42-5, Shanghai Maclean Biochemical Technology Co., Ltd.). After adding all the above mixtures, stir at 200 rpm for 10 min to allow the entire system to react rapidly. Then pour the mixture into a foaming chamber and place it at 40℃ for 24 hours to obtain the modified foam.

[0062] S4. Cut the foam into cubes of 2cm × 2cm × 2cm. Then, react the cubes in a 10% sodium carbonate solution for 6 hours, wash with water until neutral, then soak in a 2% acetic acid solution for 12 hours, wash with water until neutral, and air dry to obtain a directly applicable modified hydrophilic polyurethane carrier.

[0063] Comparative Example 1 In this comparative example, the preparation process of hydrophilic polyurethane is described in [link to relevant documentation]. Figure 1 The only difference from Example 1 is that liquid sodium polyacrylate and graphene were not added in step S3. Everything else is the same as in Example 1, and a hydrophilic polyurethane carrier is finally obtained.

[0064] Comparative Example 2 In this comparative example, the preparation process of hydrophilic polyurethane is described in [reference needed]. Figure 1 The only difference from Example 1 is that liquid sodium polyacrylate was not added in step S3, but graphene was added. Everything else is the same as in Example 1, and a hydrophilic polyurethane carrier is finally obtained.

[0065] Comparative Example 3 In this comparative example, the preparation process of hydrophilic polyurethane is described in [link to relevant documentation]. Figure 1 The only difference from Example 1 is that graphene was not added in step S3, but liquid sodium polyacrylate was added. Everything else is the same as in Example 1, and a hydrophilic polyurethane carrier is finally obtained.

[0066] Comparative Example 4 In this comparative example, the preparation process of hydrophilic polyurethane is described in [reference needed]. Figure 1 The only difference from Example 1 is that graphene was not added in step S3, but solid sodium polyacrylate was added. Everything else is the same as in Example 1, and a hydrophilic polyurethane carrier is finally obtained.

[0067] Test Example 1 The hydrophilic polyurethane carriers prepared in Example 1 and Comparative Examples 1-4 were subjected to performance tests. The test methods are as follows.

[0068] 1) Water absorption rate test: First, use an electronic balance to weigh one piece of the prepared filler separately, mass m1. Then, put one piece of filler into water. After half an hour, take it out, blot the surface moisture with filter paper, and weigh it again, mass m2. Water absorption rate = (m2 - m1) / m1 × 100%.

[0069] 2) Tensile strength shall be tested according to GB / T 6344—2008 (Test of Tensile Strength and Elongation at Break of Flexible Foam Polymer Materials). Open Cell Ratio shall be tested according to GB / T 10799—2008 (Determination of Open and Closed Cell Volume Percentage of Rigid Foam Plastics).

[0070] 3) Scanning Electron Microscopy (SEM) Testing: A small square piece of approximately 5 mm was cut from the carrier sample and immersed in deionized water for full swelling. The sample was then rapidly frozen at -80°C and transferred to a freeze dryer for 24 hours. The dried sample was then fixed to a sample post with conductive adhesive, ion-sputtered for gold plating, and observed under a scanning electron microscope. The microporous structure of the carrier surface and interior was observed using secondary electron imaging mode.

[0071] 4) Contact Angle Test: Fix the sample flat on the sample stage of the contact angle measuring instrument, ensuring the test area is flat and stress-free. Using a micro-injection device, gently drop 2 μL to 5 μL of deionized water onto the sample surface. After the droplet stabilizes for 1 to 3 seconds, quickly capture the image and measure the left and right contact angles respectively. Calculate the arithmetic mean as the water contact angle value at that measurement point.

[0072] The measurement results are shown in Table 3 below.

[0073] Table 3 Performance test results of the embodiments and comparative examples

[0074] It can be seen that the modified hydrophilic polyurethane carrier prepared in Example 1 is far superior to the unmodified hydrophilic polyurethane carrier in Comparative Example 1 in terms of hydrophilicity, water absorption rate, and tensile strength (kPa). The water absorption rate of the modified hydrophilic polyurethane carrier prepared in Example 1 is as high as 97%, which is much higher than the 82% of the unmodified carrier, indicating that the introduction of liquid sodium polyacrylate greatly enhances the hydrophilicity of the carrier. The tensile strength of the modified hydrophilic polyurethane carrier prepared in Example 1 is 890-940 kPa (average tensile strength of 900 kPa), which is much higher than that of the unmodified carrier in Comparative Example 1. It has good structural stability and can maintain its morphological integrity under long-term water flow and biofilm growth, avoiding breakage or compaction.

[0075] The scanning electron microscope image of the modified hydrophilic polyurethane carrier prepared in Example 1 is shown below. Figure 2See contact angle test photos. Figure 3 The scanning electron microscope image of the unmodified hydrophilic polyurethane carrier prepared in Comparative Example 1 is shown below. Figure 4 See contact angle test photos. Figure 5 Contact angle test photographs of the modified hydrophilic polyurethane carriers prepared in Comparative Examples 2 and 3 are shown in the figures below. Figure 6 , Figure 7 It can be seen that the contact angle of the carrier obtained in Example 1 is much smaller than that of the carriers obtained in Comparative Examples 1 and 2, indicating excellent hydrophilicity. Furthermore, the carrier obtained in Example 1 has an open porosity of 93.8%, forming a highly interconnected three-dimensional pore structure, which can provide sufficient attachment surface area and nutrient transport channels for microorganisms. The carrier obtained in Comparative Example 2 has a better contact angle and open porosity, but its strength is severely insufficient. The addition of solid sodium polyacrylate in Comparative Example 4 did not significantly improve the hydrophilicity of the filler; the resulting polyurethane foam floated on the water surface and did not sink to the bottom. Moreover, some areas of the polyurethane foam formed hard lumps. Therefore, solid sodium polyacrylate is not suitable for use in the preparation of novel hydrophilic polyurethane for electro-enhanced microbial treatment of coking wastewater, and the resulting carrier is also unsuitable for treating coking wastewater.

[0076] Application Example 1 In this application embodiment, the polyurethane carriers prepared in Example 1 and Comparative Example 1 were used in a 200mA electro-enhanced microbial treatment process for coking wastewater. The coking wastewater came from the influent of a biochemical treatment unit of a coking plant, and its main organic components were analyzed by GC-MS, as shown in Table 4 below.

[0077] Table 4 Main organic components of coking wastewater

[0078] Operating conditions: A biological aerated filter (BAF) reactor with an effective volume of 3L was selected as the research object. The performance of the modified hydrophilic polyurethane carrier prepared by adding liquid sodium polyacrylate and graphene in Example 1 and the unmodified polyurethane carrier prepared without adding either in Comparative Example 1 in electro-enhanced microbial treatment of coking wastewater were compared. Graphene electrodes were placed in the reactor, and a conductive anvil was placed on the outer layer as the negative electrode. The current was set to 200mA. The BAF with the modified hydrophilic polyurethane carrier obtained in Example 1 was named BAF1, and the BAF with the unmodified polyurethane carrier obtained in Comparative Example 1 was named BAF2. After inoculating 1L of activated sludge with a mixed liquor suspended solids concentration of 8000mg / L, coking wastewater with ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen concentrations of approximately 70mg / L, 0mg / L, and 0mg / L, respectively, was introduced. After aeration for 2 days to allow the activated sludge to fully adsorb onto the hydrophilic polyurethane carrier, all liquid in the reactor was discharged. Subsequently, the hydraulic retention time of the reactor influent was set to 24 hours, the dissolved oxygen in the reactor was controlled to be greater than 3 mg / L, coking wastewater was continuously introduced, and the changes in the concentrations of ammonia nitrogen, nitrite nitrogen and nitrate nitrogen in the influent and effluent, as well as the biomass concentration on the biofilm, including mixed liquor suspended solids (MLSS) and mixed liquor volatile suspended solids (MLVSS), were monitored.

[0079] Figure 8 The performance of different polyurethane carriers in enhancing microbial treatment of coking wastewater under a 200 mA current was demonstrated. The results showed that the carrier prepared in this invention could rapidly initiate the ammonia oxidation process, achieving optimal treatment efficiency of 99.73% within 12 days. In contrast, the polyurethane prepared without the hydrophilic agent liquid sodium polyacrylate and graphene showed very slow initiation of ammonia nitrogen oxidation, reaching optimal treatment efficiency of 98.56% after 16 days. (See [link to relevant documentation]). Figure 8 (a) and (e) in the text. Furthermore, after both reactors reached stability, their ammonia oxidation effects were similar, both achieving an ammonia oxidation efficiency exceeding 99%, and all ammonia nitrogen in the wastewater was converted to nitrate nitrogen, with no accumulation of nitrite nitrogen. See [reference needed]. Figure 8 (a)-(c) in the original text. This result indicates that the hydrophilic polyurethane carrier prepared in this invention is beneficial for the initiation of the nitrification process, significantly reducing start-up time compared to the unmodified hydrophilic polyurethane carrier obtained in Example 2 without the addition of the hydrophilic agent, liquid sodium polyacrylate and graphene. Furthermore, the COD removal performance of different polyurethane carriers in the electro-enhanced microbial treatment of coking wastewater was compared; see [reference needed]. Figure 8 As shown in (d) and (e), the results indicate that the COD removal efficiency of the polyurethane carrier BAF1 prepared in this invention is 38.81%, which is significantly higher than that of BAF2 (23.09%). Furthermore, see also... Figure 8(f) in the middle, MLSS on BAF1 (9.86 kg / m 3 (carrier) and MLVSS (5.26 kg / m 3 The carrier's MLSS (7.62 kg / m³) and MLVSS (3.76 kg / m³) were both higher than those of BAF2. 3 The presence of a carrier indicates that the hydrophilic polyurethane carrier prepared in this invention facilitates biofilm formation on its surface, thereby accelerating the establishment and activation of microbial communities.

[0080] Therefore, the novel hydrophilic polyurethane carrier prepared by this invention exhibits excellent performance in the enhanced microbial treatment of coking wastewater at 200mA.

[0081] Application Example 2 Different polyurethane carriers were applied in an electro-enhanced microbial treatment process for coking wastewater with a current of 300mA. The coking wastewater was the same as in Application Example 1.

[0082] Operating conditions: A biological aerated filter (BAF) reactor with an effective volume of 3L was selected as the research object. The performance of the modified hydrophilic polyurethane carrier prepared by simultaneously adding liquid sodium polyacrylate and graphene in Example 1 and the purchased German LEVAPOR carrier in electro-enhanced microbial treatment of coking wastewater were compared. The BAF with modified hydrophilic polyurethane prepared in Example 1 of this invention was named BAF1, and the BAF with German LEVAPOR carrier was named BAF2. Graphene electrodes were placed in the reactor, and a conductive anvil was placed on the outer layer as the negative electrode. The current was set to 300mA. After inoculating 1L of activated sludge with a mixed liquor suspended solids concentration of 8000mg / L, coking wastewater with ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen concentrations of approximately 70mg / L, 0mg / L, and 0mg / L, respectively, was introduced. After aeration for 2 days to allow the activated sludge to be fully adsorbed onto the hydrophilic polyurethane carrier, all liquid in the reactor was discharged. Subsequently, the hydraulic retention time of the reactor influent was set to 24 hours, the dissolved oxygen in the reactor was controlled to be greater than 3 mg / L, coking wastewater was continuously introduced, and the changes in ammonia nitrogen, nitrite nitrogen and nitrate nitrogen concentrations in the influent and effluent, as well as the biomass concentration on the biofilm, were monitored.

[0083] Figure 9 The performance of different polyurethane carriers in enhancing microbial treatment of coking wastewater under a 300mA current was demonstrated. The results showed that the carrier prepared in this invention could rapidly initiate the ammonia oxidation process, achieving optimal treatment effect in 14 days with a treatment efficiency of 99.78%. In contrast, conventional commercially available polyurethane BAF2 showed very slow initiation during ammonia nitrogen oxidation, reaching optimal treatment effect after 16 days with a treatment efficiency of 98.61%. (See [link to relevant documentation]). Figure 9(a) and (e) in the figure. This result shows that the hydrophilic polyurethane prepared in this invention is beneficial to the start-up process of nitrification, and significantly saves start-up time compared with conventional hydrophilic polyurethane carriers on the market. In addition, the COD removal performance of different polyurethane carriers in electro-enhanced microbial treatment of coking wastewater was compared, see [reference]. Figure 9 As shown in (d) and (e), the results indicate that the carrier prepared in this invention can rapidly initiate the ammonia oxidation process, achieving optimal treatment results within 14 days, and the treatment efficiency reaches 38.79% after stabilization. In contrast, the polyurethane of BAF2 initiates the ammonia nitrogen oxidation process more slowly, achieving optimal treatment results only after 16 days, and with a lower treatment efficiency of 30.41%. Furthermore, see [link to other documentation]. Figure 9 (f) MLSS on BAF1 (8.81 kg / m 3 (carrier) and MLVSS (4.41 kg / m 3 The carrier also had a higher MLSS (8.26 kg / m³) than BAF2. 3 (carrier) and MLVSS (3.96 kg / m 3 The modified hydrophilic polyurethane carrier prepared in this invention exhibits higher pollutant removal efficiency and higher biofilm quality and activity, even at higher currents. Therefore, the novel hydrophilic polyurethane carrier prepared in this invention demonstrates excellent performance in 300mA enhanced microbial treatment of coking wastewater.

[0084] Application Example 3 The polyurethane carriers prepared in Examples 1, 2, 3, and 1 were applied in the microbial treatment of coking wastewater. The coking wastewater was the same as that used in Example 1.

[0085] Operating conditions: A biological aerated filter (BAF) reactor with an effective volume of 2L was selected as the research object to compare the biomass performance after biofilm formation in BAFs with the carriers prepared in Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 1, respectively. Graphene electrodes were placed in the reactor, with a conductive anvil placed on the outer layer as the negative electrode, and the current was set to 200mA. The BAFs with the carriers prepared in Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 1 were named BAF1, BAF2, BAF3, and BAF4, respectively. After inoculating 1L of activated sludge with a mixed liquor suspended solids concentration of 3000 mg / L, coking wastewater with ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen concentrations of approximately 30 mg / L, 0 mg / L, and 0 mg / L, respectively, was introduced. After aeration for 2 days, all the liquid in the reactor was discharged. Subsequently, the hydraulic retention time of the reactor influent was set to 24 hours, the dissolved oxygen in the reactor was controlled to be greater than 3 mg / L, and coking wastewater was continuously introduced. After 15 days of operation, the biomass concentration on each biological carrier biofilm, including the mixed liquor suspended solids concentration (MLSS, unit kg / m³), was measured.3 Carrier) and mixed liquid volatile suspended solids concentration (MLVSS, unit kg / m³) 3 (Carrier).

[0086] The results are shown in Table 5 and Figure 10 It can be seen that the MLSS and MLVSS contents in BAF2 are slightly lower, but the MLVSS / MLSS ratio is higher. This indicates that the main function of graphene is not to increase biomass after biofilm formation, but to increase the MLVSS / MLSS ratio. This may be because graphene's conductivity promotes direct interspecies electron transfer, improves microbial energy utilization efficiency, and reduces dead cell accumulation; it selectively enriches functional microorganisms, optimizing the biofilm community structure; its conductive network maintains the activity of deep biofilms and reduces dead zones within the biofilm; and it works synergistically with sodium polyacrylate to achieve the dual advantages of hydrophilicity and conductivity, constructing a highly active biofilm matrix. Sodium polyacrylate, as a hydrophilic agent, can increase biomass after biofilm formation, thereby improving the treatment effect.

[0087] Table 5 Biomass concentration on carrier biofilm in each reactor in Application Example 3

[0088] Application Example 4 The ordinary polyurethane carrier prepared in Comparative Example 1 without the addition of liquid sodium polyacrylate and graphene, and the polyurethane carrier prepared in Comparative Example 2 without the addition of liquid sodium polyacrylate but modified with graphene, were applied in the electro-enhanced microbial treatment of coking wastewater. The coking wastewater was the same as in Application Example 1.

[0089] Operating conditions: A biological aerated filter (BAF) reactor with an effective volume of 2L was selected as the research object to compare the start-up performance of the nitrification process in BAFs with the addition of Comparative Example 1, Comparative Example 2, and the prepared carrier. Graphene electrodes were placed in the reactor, with a conductive anvil placed on the outer layer as the negative electrode, and the current was set to 200mA. The BAFs with the addition of the carriers prepared in Comparative Example 2 and Comparative Example 1 were named BAF2 and BAF4, respectively. After inoculating 1L of activated sludge with a mixed liquor suspended solids concentration of 3000 mg / L, coking wastewater with ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen concentrations of approximately 30 mg / L, 0 mg / L, and 0 mg / L, respectively, was introduced. After aeration for 2 days, all the liquid in the reactor was discharged. Subsequently, the hydraulic retention time of the reactor influent was set to 24h, the dissolved oxygen in the reactor was controlled to be greater than 3 mg / L, and coking wastewater was continuously introduced. The changes in ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen concentrations in the influent and effluent were monitored during 15 days of operation.

[0090] Figure 11The results demonstrate the performance of the polyurethane carriers prepared with Comparative Example 2 and Comparative Example 1 in enhancing the microbial treatment of coking wastewater under a 200 mA current. The results show that BAF2 with the graphene-modified carrier exhibits a faster ammonia oxidation start-up process, while BAF4 starts up very slowly in ammonia nitrogen oxidation. Furthermore, BAF2's ammonia nitrogen removal efficiency after stabilization is higher than that of BAF4. Simultaneously, during the entire operation period, the COD removal efficiency of BAF2 was 18.59%, and that of BAF4 was 16.05%. This indicates that the addition of graphene-modified polyurethane carriers is beneficial to the start-up process of nitrification, significantly saving start-up time and contributing to the electro-enhancing process, mainly due to the increased electron transfer from graphene.

[0091] It should be noted that, in this invention, unless otherwise understood in conjunction with the entire text, the expression "A and / or B" should be interpreted as any of the following three parallel cases: A; B; A and B.

[0092] It should also be noted that, in this invention, unless otherwise understood in conjunction with the entire text, the relevant terminology should be understood as follows: Relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0093] Although the invention has been disclosed above through the description of specific embodiments, it should be understood that those skilled in the art can design various modifications, improvements, or equivalents to the invention within the spirit and scope of the appended embodiments. These modifications, improvements, or equivalents should also be considered to be included within the scope of protection claimed by the invention.

Claims

1. A method for preparing a hydrophilic polyurethane carrier for electro-enhanced microbial treatment of industrial wastewater, characterized in that, Includes the following steps: S1. Prepare premixed system A according to the following mass ratio: 100 parts polyether triol, 0.2-0.4 parts N-methyldiethanolamine, 0.8-1.2 parts dibutyltin dilaurate, 0.8-1.2 parts organosilicon surfactant, 3-5 parts water, 2-4 parts dichloromethane, and 7-9 parts pore opener; S2. Prepare premixed system B according to the following mass ratio: 17-23 parts hydrophilic agent, 57-63 parts toluene diisocyanate 2,4 isomer; S3. After placing the premixed system A and B into the reactor, add 23-27 parts of liquid sodium polyacrylate with an isocyanate index R of 1.0-1.2 and 3-5 parts of graphene powder. Stir to make the whole system react quickly, and then pour it into the foaming box for foaming and curing treatment to obtain the modified foam. S4. The modified foam is cut into blocks, and the blocks are post-treated with sodium carbonate solution and acetic acid solution. After washing and drying, the modified hydrophilic polyurethane carrier is obtained.

2. The method for preparing a hydrophilic polyurethane carrier for electro-enhanced microbial treatment of industrial wastewater according to claim 1, characterized in that, In step S1, the molecular weight of the polyether triol is 3000-5000, preferably polyether triol MN3050.

3. The method for preparing the hydrophilic polyurethane carrier for electro-enhanced microbial treatment of industrial wastewater according to claim 1 or 2, characterized in that, In step S1, the pore-opening agent is at least one of ZL K-360, ZL Y-1900 and GSY-28.

4. The method for preparing a hydrophilic polyurethane carrier for electro-enhanced microbial treatment of industrial wastewater according to any one of claims 1-3, characterized in that, In step S2, the hydrophilic agent is a polyether-modified copolymer surfactant; further, the hydrophilic agent is at least one of ZL-480 and Xt-9093.

5. The method for preparing a hydrophilic polyurethane carrier for electro-enhanced microbial treatment of industrial wastewater according to any one of claims 1-4, characterized in that, In step S1, premixed system A is prepared according to the following mass ratio: 100 parts polyether triol, 0.3 parts N-methyldiethanolamine, 1 part dibutyltin dilaurate, 1 part silicone surfactant, 4 parts water, 3 parts dichloromethane, and 8 parts pore-opening agent; and / or, In step S2, premixed system B is prepared according to the following mass ratio: 20 parts hydrophilic agent, 60 parts toluene diisocyanate 2,4 isomer; and / or, In step S3, 25 parts of liquid sodium polyacrylate with an isocyanate index R of 1.0-1.2 and 4 parts of graphene powder are added.

6. The method for preparing a hydrophilic polyurethane carrier for electro-enhanced microbial treatment of industrial wastewater according to any one of claims 1-5, characterized in that, In step S3, the stirring is performed at a speed of 150-300 rpm for 8-15 minutes, for example, at a speed of 200 rpm for 10 minutes; and / or, After the material is poured into the foaming box, it should be placed at 30-60℃ for 20-30 hours, for example, at 40℃ for 24 hours.

7. The method for preparing a hydrophilic polyurethane carrier for electro-enhanced microbial treatment of industrial wastewater according to any one of claims 1-6, characterized in that, In step S4, the post-processing includes: reacting the block foam in a 10% sodium carbonate solution for 5-7 hours, washing with water until neutral, then soaking in a 2% acetic acid solution for 10-15 hours, washing with water until neutral, and drying to obtain the modified hydrophilic polyurethane carrier.

8. A hydrophilic polyurethane carrier for electro-enhanced microbial treatment of industrial wastewater, characterized in that, It is prepared by any one of the preparation methods described in claims 1-7.

9. The application of the hydrophilic polyurethane carrier as described in claim 8 in the electro-enhanced microbial treatment of industrial wastewater.

10. The application according to claim 9, wherein the industrial wastewater is coking wastewater; Preferably, the current is 200-300 mA during the processing.

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