A waste gas purification method based on nutrient slow-release biological filler

Abstract

The present invention relates to a waste gas purification method based on nutrient slow-release biological filler, comprising the following steps: 1. preparing nutrient slow-release biological filler; 2. preparing modified polyurethane sponge filler; 3. configuring culture nutrient solution and domestication nutrient solution, and cultivating and domesticating activated sludge in a bioreactor; 4. loading the nutrient slow-release biological filler of step 1 and the modified polyurethane sponge filler of step 2 into a biotrickling filter as fillers of a packing layer; 5. injecting the activated sludge domesticated in step 3 into the biotrickling filter, and forming microbial biofilms on the filler surface; 6. dripping the domestication nutrient solution of step 3 into the top of the biotrickling filter and flowing it out from the bottom of the filter to realize the circulation of the domestication nutrient solution; 7. exhaust gas enters the bottom of the biotrickling filter and is discharged from the top of the filter after being treated by the packing layer. The method of the present invention has the characteristics of high purification efficiency, strong system stability, energy saving and carbon reduction, and environmental friendliness, and has stronger adaptability under different working conditions.

Description

Technical Field

[0001] The present invention belongs to the technical field of waste gas treatment, and in particular relates to a waste gas purification method based on nutrient slow-release biological filler. Background Art

[0002] Excessive VOC emissions into the atmosphere not only contribute to the formation of certain secondary pollutants and cause severe weather, but also directly endanger human health. VOC purification methods primarily include physical, chemical, and biological methods, with biological methods attracting widespread attention due to their low cost, lack of secondary pollution, and environmental friendliness.

[0003] Biological methods primarily include biofiltration, biotrickling filtration, and bioscrubbing. Biotrickling filtration systems offer advantages such as low operating costs, minimal pressure drop during long-term operation, and the ability to centrally treat volatile organic compounds and acidic, malodorous gases. Packing is a key component of biotrickling filters, supporting the growth of biofilms and microorganisms and facilitating the adsorption of pollutants, ensuring sufficient residence time for gaseous pollutants to degrade. Therefore, packing plays a crucial role in pollutant removal.

[0004] At present, although various new fillers have emerged one after another, the Chinese patent application number 201810046315.8 discloses a biological fluidized bed filler for waste gas purification and its preparation method. The filler has a polymer lightweight material with a particle size of 0.5 to 5 mm as the skeleton. The surface of the polymer lightweight material is at least partially coated with a solid biocatalytic reaction layer loaded with pollutant-degrading bacteria and nutrients. The coating thickness is 0.1 to 2 mm. By controlling the density of the filler itself, the filler can be put into a fluidized state. However, most of these fillers remain in the laboratory stage, and more research and practice are needed for their actual and widespread application in industrial equipment. Common fillers in biological trickling filters are mostly natural inert fillers and organic synthetic fillers, with polyurethane sponge fillers being the most common. Polyurethane sponge fillers now have a certain basis for industrial application. The Chinese patent with application number 202111536601.0 discloses a modified polyurethane sponge filler, its preparation method and use, including: a polyurethane sponge matrix, and activated carbon powder adhered to its surface, and positive charges loaded on its surface and / or inside; the polyurethane sponge matrix is ​​a polyurethane sponge after oxidation corrosion. Although polyurethane sponge has a large porosity and specific surface area, it usually lacks the nutrients required by microorganisms, resulting in slow biofilm formation. Synthetic fillers such as polyurethane sponges and polyhedral hollow spheres have poor surface properties and are difficult to fix microorganisms, resulting in low biofilm formation efficiency, and the circulating liquid requires long-term addition of nutrient solution. Therefore, it is necessary to develop a method for preparing nutrient-slow-release biological fillers and waste gas purification methods that have high biofilm formation efficiency, slowly release nutrients required for microbial growth, have good exhaust gas purification effects, and save energy (reduce the amount of nutrients added). Summary of the Invention

[0005] To overcome the shortcomings of the above-mentioned existing technologies and achieve widespread high-efficiency and energy-saving applications in conjunction with biotrickling filter technology, the present invention provides a waste gas purification method based on nutrient-slow-release biological fillers. This method has the characteristics of high purification efficiency, strong system stability, energy conservation and carbon reduction, and environmental friendliness, and has greater adaptability under different working conditions. The technical solution adopted by the present invention is:

[0006] The present invention provides a waste gas purification method based on nutrient slow-release biological filler, comprising the following steps:

[0007] Step 1, preparing a nutrient slow-release biological filler;

[0008] Step 2, preparing modified polyurethane sponge filler;

[0009] Step 3: preparing a culture nutrient solution and an acclimation nutrient solution, and culturing and acclimating the activated sludge in the bioreactor;

[0010] Step 4: The nutrient slow-release biological filler of step 1 and the modified polyurethane sponge filler of step 2 are loaded into the biological trickling filter as fillers of the filler layer;

[0011] Step 5: injecting the activated sludge acclimated in step 3 into the bio-trickling filter to form microbial biofilm on the surface of the filler;

[0012] Step 6: dripping the domesticated nutrient solution from step 3 into the top of the bio-trickling filter and letting it flow out from the bottom of the filter to achieve a circulating flow of the domesticated nutrient solution;

[0013] In step seven, the waste gas enters the biotrickling filter from the bottom and is discharged from the top of the tower after being treated by the packing layer.

[0014] Furthermore, in step 1, the preparation process of the nutrient slow-release biological filler includes the following steps: S1, adding 9% polyvinyl alcohol and 4% sodium alginate to 100 ml of deionized water, mixing and stirring, and heating at a constant temperature of 95-130°C until completely dissolved to obtain a gel solution; S2, adding 20% ​​citric acid-soluble fertilizer, 6% activated carbon powder, and 2% calcium carbonate powder to the gel solution, mixing evenly, and letting it stand for 1 hour to obtain a cross-linked suspension, and making a spherical slow-release filler, and controlling the particle size to be 1-2 cm; S3, preparing a saturated boric acid-2% calcium chloride solution, adjusting the pH value to between 5.0 and 5.3, placing the spherical slow-release filler into the above-mentioned saturated boric acid-2% calcium chloride solution, and cross-linking at 3-4°C for 24 hours; S4, washing the cross-linked slow-release filler and air-drying. Furthermore, in step 2, the preparation process of the modified polyurethane sponge filler includes the following steps: (1) preparing a modified suspension; (2) immersing a polyurethane sponge in the modified suspension to allow the modified suspension to be loaded on the surface of the polyurethane sponge; (3) immersing the loaded polyurethane sponge in a cross-linking solution, adjusting the pH of the cross-linking solution to 3.5-6.0, and cross-linking for 24 hours; (4) washing the cross-linked polyurethane sponge with distilled water and air-drying it in a ventilated place; after air-drying, maintaining the polyurethane sponge at 165° C. for 1-10 minutes to obtain a modified polyurethane sponge filler.

[0015] Furthermore, in step (1), the modified suspension comprises the following components, calculated by mass fraction: 3%-5% polyvinyl alcohol, 5%-7% sodium alginate, 3%-5% citrate-soluble fertilizer, 0.5%-1.5% activated carbon, 1%-3% calcium carbonate, and the balance is distilled water; the preparation method of the modified suspension is: heating polyvinyl alcohol and sodium alginate in distilled water until completely dissolved, adding activated carbon, stirring for 20-40 minutes, adding citrate-soluble fertilizer and calcium carbonate, stirring evenly, and standing for 2-3 hours to obtain the modified suspension.

[0016] Furthermore, in step (2), the polyurethane sponge is immersed in the modified suspension for not less than 30 seconds, and the mass ratio of the modified suspension to the polyurethane sponge is: 10-15g of the modified suspension is attached to the surface of a 3cm×3cm×3cm cube of polyurethane sponge.

[0017] Furthermore, in step (3), the cross-linking liquid is a saturated boric acid solution containing 2% calcium chloride, and the mass ratio of the cross-linking liquid to the loaded polyurethane sponge is: 10 loaded polyurethane sponges are immersed in every 600 mL of cross-linking liquid, and the polyurethane sponge in each loaded polyurethane sponge is a 3cm×3cm×3cm cube; the pH of the cross-linking liquid is adjusted to 4, and cross-linking is carried out for 24 hours; in step (4), high-temperature treatment is performed at 165°C for 3 minutes.

[0018] Furthermore, in step three, the process of acclimating the activated sludge is as follows: first, culturing the sludge for 10-15 days, aerating it for 12 hours daily, and replacing the supernatant after the sludge sedimentation with fresh culture nutrient solution daily, with the replacement volume being 5% of the supernatant volume; then acclimating the sludge for another 7-10 days, aerating it for 12 hours daily, and replacing the supernatant after the sludge sedimentation with fresh acclimation nutrient solution daily, with the replacement volume being 5% of the supernatant volume, and then adding a liquid target pollutant at 0.1% of the supernatant volume after the replacement;

[0019] The culture nutrient solution contains the following components in concentrations: glucose 0.3 g / L, urea 0.05 g / L, K2HPO4 0.15 g / L, MgSO4 0.225 g / L, CaCl2 0.275 g / L, FeSO4 0.025 g / L, and the rest is deionized water; the acclimation nutrient solution contains the following components in concentrations: NH4Cl 0.3 g / L, MgCl2 0.1 g / L, CaCl2 0.1 g / L, K2HPO4 0.5 g / L, NaH2PO4 0.5 g / L, MnSO4 0.3 g / L, CuSO4 0.01 g / L, ZnSO4·7H2O 0.01 g / L, FeSO4·7H2O 0.01 g / L, and the rest is deionized water.

[0020] Furthermore, in step 4, a liquid diversion device is provided at the top of the biotrickling filter; the liquid diversion device comprises a liquid inlet pipe (11), which is connected to a plurality of diversion pipes (12) facing in different directions on the outer periphery of the lower portion of the liquid inlet pipe (11), and each of the diversion pipes (12) is connected to a plurality of branch pipes (13) facing in different directions below.

[0021] Furthermore, in step five, the activated sludge acclimated in step three is injected into the biotrickling filter tower so that it covers all the packing layers for 48 hours, and aerated for 12 hours every 12 hours. After 48 hours, the activated sludge is discharged from the bottom of the biotrickling filter tower.

[0022] Furthermore, in step 6, the circulating liquid for spraying on the packing surface in the biotrickling filter is sprayed into the biotrickling filter every day for 12 hours; in step 7, the waste gas to be treated is introduced from the bottom of the tower, and the concentration range of the waste gas to be treated is 80-500 mg / m 3 The ratio of the circulating liquid flow rate to the inlet flow rate of the waste gas to be treated is 0.0005-0.002:1.

[0023] The beneficial effects of the present invention are:

[0024] 1. Rapid biofilm formation and slow nutrient release. In order to achieve rapid biofilm formation in the biotrickling filter in industrial applications and reduce the amount of nutrients added during operation, one of the first purposes of the present invention is to provide a nutrient slow-release biological filler. The filler is a viscous liquid formed by heating polyvinyl alcohol and sodium alginate as a matrix, activated carbon and calcium carbonate as a skeleton carrier, and a microcapsule structure is formed inside the filler. Under the cross-linking environment of polychloroethanol, citric acid-soluble fertilizers are fused and coated to modify the surface of the microcapsule structure inside the filler to form a slow-release effect. During use, under the coupling of capillary action, pump suction and the environment, nutrients are gradually precipitated to achieve sustained release. The second filler is a modified polyurethane sponge filler. Due to the specific modified compatibility, modified suspension and modification process of the present invention, organic crosslinking of citric acid-soluble fertilizer and polyurethane sponge is achieved, the polyurethane sponge is embedded in the pores, the surface micropores and pores are reshaped, and its special structure is improved, which is more suitable for microbial biofilm formation. The biofilm formation period of the filler is shortened, the biofilm formation effect is improved, and the contact area between the gas and the filler is increased; after modification, it contains three hydrophilic groups, namely primary alcohol (1500-1260cm -1 ), which belongs to the deformation vibration of hydroxyl plane; the stretching vibration of hydrogen and oxygen of carboxylic acid (2500~3300cm -1 ); free hydroxyl group (3650~3610cm -1 These three hydrophilic groups possess high hydrophilicity and serve as channels connecting the inside and outside of the filler, allowing nutrients to dissolve and release. The reshaped pores promote a sustained release effect and enhance the filler's inherent water-holding capacity, which helps maintain a favorable microbial environment. This results in higher removal efficiencies when purifying waste gas, especially hydrophobic waste gas.

[0025] 2. The circulating liquid is sprayed more evenly. Since a liquid diversion device is added to the circulating liquid inlet of the biotrickling filter, the circulating liquid can be sprayed more evenly on the packing surface, improving the problem of uneven diversion effect of the traditional diversion network and wet inside and dry outside of the packing layer.

[0026] 3. Higher removal efficiency. A second objective of the present invention is to provide a method for waste purification using a nutrient-slow-release biofiller. The biotrickling filter is filled with a mixed packing consisting of a nutrient-slow-release biofiller and a modified polyurethane sponge packing. The spray circulating fluid does not require the addition of nutrients such as nitrogen, phosphorus, and potassium. Highly efficient waste removal is achieved by controlling the air velocity, liquid-to-solid ratio, and pressure drop.

[0027] 4. Good system stability. The mixed filler consisting of nutrient-slow-release biological filler and modified polyurethane sponge filler is self-sustaining in nutrients, has a high abundance of biofilm on the filler surface, and contains trace amounts of activated carbon. It has strong resistance to shock loads and can demonstrate more stable removal efficiency when conditions such as inlet concentration and flow rate change.

[0028] 5. Reduced costs and operational difficulty. The combination of slow-release nutrient biofiller and modified polyurethane sponge filler in the biotrickling filter can achieve long-term and slow release of the nutrients required by microorganisms, eliminating the need to supplement nitrogen, phosphorus, and potassium nutrients in the circulating fluid. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The scanning electron microscope images of the surface of the nutrient-slow-release biological filler at different magnifications;

[0030] Figure 2 The scanning electron microscope images of the modified polyurethane foam filler surface at different magnifications;

[0031] Figure 3 Scanning electron microscope images of the interior of modified polyurethane foam filler at different magnifications

[0032] Figure 4 To modify the micropore and mesopore distribution of polyurethane foam;

[0033] Figure 5 TG and DTG curves of modified polyurethane foam filler;

[0034] Figure 6 This is the infrared analysis result of modified polyurethane foam filler;

[0035] Figure 7 It is a schematic diagram of the structure of the device of the present invention.

[0036] In the accompanying drawings, 1 is a gas flow meter inlet, 2 is a gas flow meter, 3 is an air hole, 4 is a water stop clamp, 5 is a biotrickling filter, 6 is a packing layer, 7 is a liquid diversion device, 8 is a circulating liquid holding tank, 9 is a peristaltic pump, and 10 is a bioreactor;

[0037] Figure 8 Schematic diagram of the structure of the liquid diversion device;

[0038] In the accompanying drawings, 11 is a liquid inlet pipe, 12 is a diverter pipe, 13 is a branch pipe, and 14 is a fixed wire. DETAILED DESCRIPTION

[0039] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0040] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0041] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0042] Unless otherwise specifically stated, the relative arrangement of the parts and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to actual proportional relationships. The techniques, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the techniques, methods and equipment should be considered as part of the authorization specification. In all examples shown and discussed here, any specific values ​​should be interpreted as being merely exemplary and not as limitations. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following figures, and therefore, once an item is defined in one figure, it does not need to be further discussed in subsequent figures.

[0043] Example 1-2 Preparation of nutrient slow-release biological filler

[0044] Example 1

[0045] The preparation process of nutrient slow-release biological filler includes the following steps:

[0046] S1. Prepare a gel solution by adding polyvinyl alcohol and sodium alginate to 100 ml of deionized water to form a mixture, wherein the mass fraction of polyvinyl alcohol in the mixture is 9% and the mass fraction of sodium alginate is 4%. Heat the mixture in a constant temperature magnetic stirrer at 95°C until completely dissolved, thereby obtaining a gel solution. The polyvinyl alcohol is in granular form, the sodium alginate is in powder form, and the calcium carbonate is in powder form without pretreatment. The activated carbon is in columnar form. The citric acid-soluble fertilizer and the columnar activated carbon are pulverized separately using a crusher, and the pulverized mixture is passed through a 200-mesh sieve for later use.

[0047] S2, extrusion granulation: 20% citric acid-soluble fertilizer, 6% activated carbon powder, and 2% calcium carbonate powder are added to the gelling liquid and mixed uniformly to form a mixed gelling liquid. The mass fraction of the citric acid-soluble fertilizer, the mass fraction of the activated carbon powder, and the mass fraction of the calcium carbonate powder are 20%, 6%, and 2%, respectively. The mixed gelling liquid is then allowed to stand for 1 hour to allow internal crosslinking of the polyvinyl alcohol, resulting in a crosslinked suspension. Spherical sustained-release fillers are then produced by extrusion granulation, with a particle size of 1-2 cm.

[0048] The citrate-soluble fertilizer contains nitrogen, phosphorus, potassium, magnesium oxide, sulfur, calcium oxide and trace elements, wherein 35% of the nitrogen element is nitrate nitrogen and 65% is ammonium nitrogen; 100% of the phosphorus element is neutral ammonium citrate-soluble phosphorus, of which 65%-85% is water-soluble phosphorus; the potassium element is red bull potassium sulfate; the mass fractions of other components are 0.2-4% of magnesium oxide, 0.7-8% of sulfur and 1.5-11% of calcium oxide; and the trace elements include iron, copper and zinc.

[0049] S3, preparing a saturated boric acid-2% calcium chloride solution, wherein the saturated boric acid-2% calcium chloride solution is prepared by adding 2% (mass fraction) calcium chloride to a saturated boric acid solution, and adjusting the pH value of the solution to 5.1 using sodium carbonate, and then placing the sustained-release filler into the above saturated boric acid-2% calcium chloride solution and cross-linking at 3.5°C for 24 hours.

[0050] S4, the cross-linked sustained-release filler is rinsed with deionized water and air-dried for later use.

[0051] Example 2

[0052] The difference between this embodiment and embodiment 1 is that in step S1 of this embodiment, the mixture is placed in a constant temperature heating magnetic stirrer and heated at a constant temperature of 130° C. until it is completely dissolved to obtain a gelled liquid.

[0053] Step S3, preparing a saturated boric acid-2% calcium chloride solution, adjusting the pH value to 5.0, placing the spherical sustained-release filler into the saturated boric acid-2% calcium chloride solution, and crosslinking at 3°C ​​for 24 hours;

[0054] Example 3

[0055] The difference between this embodiment and embodiment 1 is that in step S1 of this embodiment, the mixture is placed in a constant temperature heating magnetic stirrer and heated at a constant temperature of 100° C. until it is completely dissolved to obtain a gelled solution.

[0056] Step S3, preparing a saturated boric acid-2% calcium chloride solution, adjusting the pH value to 5.3, placing the spherical sustained-release filler into the saturated boric acid-2% calcium chloride solution, and crosslinking at 4°C for 24 hours;

[0057] The nutrient slow-release biological filler prepared by the preparation method of Example 1 was characterized. Figure 1 The scanning electron microscope images of the surface of the nutrient slow-release biological filler at different magnifications are as follows: the diameter of the spherical filler is 10-20 mm, the bulk density is 1030 kg / m 3 , true density 2000kg / m 3 , porosity 48.5%, saturated water content 1.69g / g, specific surface area 285m 2 / g, pH=7.2, pores with diameters of 1.7nm and 2.6nm occupy the largest pore volume, and the pore structure of the filler is mainly micropores and mesopores.

[0058] Depend on Figure 1 (a) It can be seen that the filler is dark gray and rough when observed with the naked eye. It feels like sandpaper and has a hard texture when touched. It does not deform when squeezed hard. Figure 1 (b) shows the surface characteristics of the filler under a 40x scanning electron microscope. It can be found that there are many concave and convex structures on the surface of the filler, which is also the reason for the roughness of the filler surface. In addition, many pore structures can be observed, which increases the specific surface area of ​​the filler. Figure 1 In (c), the pore structure characteristics of the filler surface can be seen more clearly. Combined with the scale of the picture, it can be calculated that the pore range of the filler surface pore structure is between 5-30μm. The pores on the filler surface not only allow the entry of microorganisms and pollutants, which is beneficial to increase the contact area between microorganisms and pollutants, but also better fix microorganisms and reduce the loss of microorganisms caused by circulating fluid flushing; the structural characteristics inside the pores are as follows: Figure 1 As shown in (d), the cross-linked structure of polyvinyl alcohol and sodium alginate can be seen, which is conducive to the exudation of nutrients inside the filler.

[0059] Among the characteristic parameters, the diameter was measured by a ruler, the saturated water content was measured by the mass change before and after immersion in water for 24 hours, the specific surface area and pore size were measured by the NOVA2000e specific surface area and pore size meter produced by Quantachrome, USA, and the scanning electron microscopy was completed by the Analysis and Testing Center of Hebei University of Science and Technology.

[0060] Example 2

[0061] The present invention will now be further described based on the daily nutrient release capacity of the nutrient slow-release biological filler in water. This embodiment is intended to further illustrate the nutrient slow-release capacity of the nutrient slow-release biological filler.

[0062] Weigh 10 g of the nutrient-slow-release biofiller from Example 1 and immerse it in 1000 mL of deionized water. Measure the total nitrogen, total phosphorus, and potassium concentrations in the deionized water every 24 hours. Stir the filler and deionized water thoroughly before measurement, and replace the deionized water afterward. Total nitrogen in the filler extract was determined by alkaline potassium persulfate digestion followed by UV spectrophotometry; total phosphorus was determined by ammonium molybdate spectrophotometry; and potassium was determined by flame atomic absorption spectrophotometry.

[0063] After 30 days of measurement, the cumulative release of nitrogen, phosphorus, and potassium from the nutrient-slow-release biofiller over 30 days was 3.319 mg / g, 4.463 mg / g, and 8.039 mg / g, respectively. During the first two days, the filler rapidly released water-soluble nutrients, with a rapid release rate, reaching peak concentrations of 2.98 mg / L for total nitrogen, 6.23 mg / L for total phosphorus, and 9.46 mg / L for potassium, respectively. After 15 days of measurement, the released concentrations of total nitrogen, total phosphorus, and potassium gradually decreased and stabilized, indicating that the water-soluble nutrients were essentially consumed, leaving only the soluble nutrients to function. After 15 days, the average daily release concentrations were 1.25 mg / L, 0.19 mg / L, and 0.10 mg / L, respectively, with average release rates of 0.57%, 2.79%, and 0.13%, respectively, indicating a slow release of nutrients from the filler.

[0064] Example 3-5 Preparation of modified polyurethane sponge filler

[0065] Example 3

[0066] The preparation of the modified polyurethane sponge filler and the sustained-release capability experiment in this embodiment are further described in detail for the present invention.

[0067] The preparation process of modified polyurethane sponge filler comprises the following steps:

[0068] (1) preparing a modified suspension, wherein the modified suspension is prepared by controlling a certain addition sequence and component content, heating temperature, stirring intensity, and residence time so that the slow-release citric acid-soluble fertilizer is organically combined with other materials to form a liquid / solid suspension.

[0069] The raw materials required for the modified suspension include polyvinyl alcohol, sodium alginate, citrate-soluble fertilizer, activated carbon, calcium carbonate and distilled water. The modified suspension includes the following components in mass fraction: polyvinyl alcohol 3%-5%, sodium alginate 5%-7%, citrate-soluble fertilizer 3%-5%, activated carbon 0.5%-1.5%, calcium carbonate 1%-3%, and the balance is distilled water. In this embodiment, the modified suspension includes the following components in mass fraction: polyvinyl alcohol 4%, sodium alginate 6%, citrate-soluble fertilizer 4%, activated carbon 1%, calcium carbonate 2%, and the balance is distilled water.

[0070] The preparation method is as follows: polyvinyl alcohol and sodium alginate are heated in distilled water until completely dissolved, the heating temperature is 90°C, the solvent can be completely dissolved after 1 hour, the heating temperature can be appropriately increased to shorten the dissolution time, activated carbon is added, and after stirring for 20 minutes, calcium carbonate and citrate-soluble fertilizer are added in sequence, and the mixture is stirred evenly at a stirring intensity of 40-60 rpm, and the mixture is allowed to stand for 2 hours to obtain a modified suspension.

[0071] (2) The polyurethane sponge is immersed in the modified suspension by an impregnation method, so that the modified suspension is loaded on the surface of the polyurethane sponge. Specifically, the polyurethane sponge is immersed in the modified suspension for no less than 30 seconds. In this embodiment, the impregnation is 30 seconds. The modified suspension is loaded on the surface of a 3cm×3cm×3cm cubic polyurethane sponge by the impregnation method. When scaling up production or industrializing the present invention, the ratio of the modified suspension to the polyurethane sponge can be calculated according to the following ratio. The mass ratio of the modified suspension to the polyurethane sponge is: 10-15g of the modified suspension is loaded on the surface of a 3cm×3cm×3cm cubic polyurethane sponge. In this embodiment, 13g of the modified suspension is loaded on the surface of a 3cm×3cm×3cm cubic polyurethane sponge. The modified suspension and polyurethane sponge must have a specific loading amount, because under the loading amount of this application, the micropores and pores on the surface of the modified polyurethane sponge are reshaped while retaining the original pore structure. The pore structure is mainly micropores and mesopores, which has an important impact on biological film formation and waste gas treatment.

[0072] (3) Immerse the loaded polyurethane sponge in a cross-linking solution, adjust the pH of the cross-linking solution to 5, and cross-link for 24 hours. In this embodiment, preferably, adjust the pH of the cross-linking solution to 4, and cross-link for 24 hours.

[0073] The cross-linking liquid is a saturated boric acid solution containing 2% calcium chloride. The mass ratio of the cross-linking liquid to the polyurethane sponge is: 10 loaded polyurethane sponges are immersed in every 600 mL of the cross-linking liquid, and the mass ratio is about 40:1.

[0074] (4) Wash the cross-linked polyurethane sponge with distilled water and air-dry it in a ventilated place. After air-drying, place the polyurethane sponge in an oven and heat-treat it at 165° C. for 1-10 minutes to obtain a modified polyurethane sponge filler. In this embodiment, the heat-treating is preferably performed at 165° C. for 3 minutes.

[0075] Five modified polyurethane sponge biofillers obtained by the above method were immersed in 1000 mL of distilled water. The concentrations of total nitrogen, total phosphorus, and potassium in the distilled water were measured every 24 hours. The fillers and distilled water were thoroughly stirred before measurement, and the distilled water was replaced after measurement. Total nitrogen in the filler extract was determined by alkaline potassium persulfate digestion followed by UV spectrophotometry; total phosphorus was determined by ammonium molybdate spectrophotometry; and potassium was determined by flame atomic absorption spectrophotometry.

[0076] The measurement of 30d shows that the cumulative release of the present embodiment modified polyurethane sponge filler nitrogen, phosphorus and potassium in 30 days is respectively 0.671mg / g, 0.911mg / g, and 1.507mg / g. The present embodiment filler is the quick release of water-soluble nutrients in initial two days, and release rate is very fast. The maximum concentration of total nitrogen, total phosphorus and potassium can reach 0.586mg / L, 1.346mg / L, and 1.792mg / L respectively. The release concentration of total nitrogen, total phosphorus and potassium observed through 15d gradually declines and tends to be stable, illustrating that water-soluble nutrients are consumed substantially, and only the remaining citric acid soluble nutrients play a role. After 15d, the average release concentration every day is respectively 0.273mg / L, 0.038mg / L, and 0.026mg / L, and the filler nutrient element releases slowly.

[0077] Example 4

[0078] The difference between this embodiment and embodiment 3 is that (1) in this embodiment, the modified suspension comprises the following components, by mass fraction: 3% polyvinyl alcohol, 7% sodium alginate, 3% citrate-soluble fertilizer, 1.5% activated carbon, 1% calcium carbonate, and the balance being distilled water. The polyvinyl alcohol and sodium alginate were heated in distilled water at 93° C. for 1 hour until completely dissolved, and then the activated carbon was added. After stirring for 25 minutes, the calcium carbonate and citrate-soluble fertilizer were added in sequence, and the mixture was stirred uniformly at 50-60 rpm. The mixture was allowed to stand for 2 hours to obtain the modified suspension.

[0079] (2) The polyurethane sponge was immersed in the modified suspension for 50 seconds. The mass ratio of the modified suspension to the polyurethane sponge was: 10 g of the modified suspension was attached to the surface of a 3 cm*3 cm*3 cm cubic polyurethane sponge.

[0080] (3) The polyurethane sponge loaded with the modified liquid is immersed in a cross-linking liquid, the pH of the cross-linking liquid is adjusted to 3.5-6.0, and the cross-linking is carried out for 24 hours. In this embodiment, the pH of the cross-linking liquid is adjusted to 3.5, and the cross-linking is carried out for 24 hours.

[0081] The mass ratio of the cross-linking liquid to the polyurethane sponge is 40:1.

[0082] (4) After air drying, the modified cross-linked polyurethane sponge was placed in an oven and subjected to high-temperature treatment at 165°C for 10 min to obtain a modified polyurethane sponge filler.

[0083] Example 5

[0084] The difference between this embodiment and embodiment 3 is that: (1) In this embodiment, the modified suspension comprises the following components in the following amounts, by mass: 5% polyvinyl alcohol, 5% sodium alginate, 5% citrate-soluble fertilizer, 0.5% activated carbon, 3% calcium carbonate, and the balance being distilled water. The polyvinyl alcohol and sodium alginate were heated in distilled water at 95° C. for 1 hour until completely dissolved, and then the activated carbon was added. After stirring for 20 minutes, the calcium carbonate and citrate-soluble fertilizer were added in sequence, and the mixture was stirred uniformly at 50-60 rpm. The mixture was allowed to stand for 2 hours to obtain the modified suspension.

[0085] (2) The polyurethane sponge was immersed in the modified suspension for 80 seconds. The mass ratio of the modified suspension to the polyurethane sponge was: 15 g of the modified suspension was loaded on the surface of a 3 cm*3 cm*3 cm cubic polyurethane sponge.

[0086] (3) Immerse the polyurethane sponge loaded with the modification liquid in a crosslinking liquid, adjust the pH of the crosslinking liquid to 6.0, and crosslink for 24 hours. The mass ratio of the crosslinking liquid to the polyurethane sponge loaded with the modification liquid is 40:1.

[0087] (4) After air drying, the modified cross-linked polyurethane sponge was placed in an oven and subjected to high temperature treatment at 165° C. for 1 min to obtain a modified polyurethane sponge filler.

[0088] Performance Analysis of Modified Polyurethane Sponges of Examples 6-9

[0089] Example 6

[0090] In order to understand the microstructure of the filler, some filler fragments were randomly selected and the surface and internal structure of the filler fragments were observed using a scanning electron microscope (S-4800-1), a high-resolution cold field emission scanning electron microscope produced by Hitachi, Japan. The filler microstructure observed by the scanning electron microscope is as follows: Figure 2 and Figure 3 shown. Figure 2 The microstructure of the filler surface is shown in the figure. At lower magnifications (a and b), the filler surface is relatively rough, with numerous tiny pores. At higher magnifications (c and d), the microporous structure of the filler surface is clearly visible, with the pore size calculated from the scale in the figure to be between 5 and 30 μm. The pore structure on the filler surface not only provides a larger specific surface area, but also allows for the better release of nutrients within the filler through these pores. The release rate of these nutrients can be controlled by varying the pore size.

[0091] Figure 3This is the microstructure inside the filler. As can be seen from the figure, at a lower magnification (left), there are also many pore structures inside the filler, as well as many gap structures, which are conducive to the transportation of nutrients inside the filler to the outside and improve the utilization rate of nutrients; at a larger magnification (right), it can be observed that there are many flocculent structures inside the filler, which is the result of cross-linking of polyvinyl alcohol and sodium alginate. These flocculent structures can make the nutrients more evenly dispersed inside the filler.

[0092] Example 7

[0093] In addition to the macroporous structure (pore size greater than 50nm), the filler also contains many micropores and mesopores. The distribution of micropores and mesopores measured by the NOVA2000e specific surface area pore size analyzer produced by Quantachrome Corporation in the United States is as follows: Figure 4 shown.

[0094] As shown in the figure, the pore volume occupied by the hole with an pore diameter of 1.7nm and 2.6nm is the largest, which proves that it accounts for a large proportion, and the contribution to specific surface area is the largest; the hole with an pore diameter greater than 2nm accounts for a large proportion in the filler, indicating that the pore structure of the filler is mainly mesopore. Due to the presence of micropores and mesopores, the release of fertilizer nutrients in the filler is controlled, and the long-term slow release of citric acid-soluble nutrients can be achieved, and the macroporous structure in Example 4 is more conducive to the rapid release of water-soluble nutrients in the filler. The pore structure of non-empty aperture not only ensures the rapid release of nutrients, but also ensures the slow release in long-term use.

[0095] Example 8

[0096] In order to verify the thermal stability of the modified polyurethane sponge filler, the temperature was set to 20 °C and then heated to 800 °C at a rate of 5 °C min-1 using a differential thermal and thermogravimetric simultaneous measuring device DTG-60H produced by Shimadzu, Japan. -1 The atmosphere is air, and the thermal stability of the filler is analyzed by the change of sample mass with increasing temperature.

[0097] The results are as follows Figure 5As shown in the figure, the thermal degradation rate of the filler has six peaks with relatively obvious rate changes, which can be roughly classified into five stages of filler thermal degradation: the first stage is from 21 to 100°C, and the weight loss is mainly due to the evaporation of water and other volatile substances in the filler; the second stage is from 100 to 170°C, during which the polyvinyl alcohol will gradually change color and become brittle due to dehydration, and lose its solubility due to dehydration and etherification at 160 to 170°C; the third stage is from 200 to 360°C, in which there are two relatively obvious peaks, including the elimination of the polyvinyl alcohol macromolecular side chain to form water molecules and small molecules of benzene, aldehyde, and ketone combustible substances, as well as the thermal decomposition of unstable oxygen-containing functional groups such as hydroxyl groups in sodium alginate and the dissolution and evaporation of polyurethane foam; the fourth stage is from 450 to 550°C, which mainly includes the thermal degradation of polyvinyl alcohol and the molecular chain skeleton of sodium alginate; the fifth stage is the formation of residual carbon when the temperature exceeds 550°C. The final residual carbon mass is 2.02 mg, accounting for 27.87% of the total mass of the sample. During actual operation, the temperature is generally 25-35°C, at which time the microbial activity is relatively high. Thermogravimetric experimental results show that the mass loss at 35°C is only 0.04 mg, accounting for 0.5% of the total mass, proving that the filler has good thermal stability.

[0098] Example 9

[0099] Infrared analysis results of modified polyurethane foam filler Figure 6 As shown in the figure, the modified polyurethane foam filler contains three hydrophilic groups, namely primary alcohol (1500-1260cm -1 ), which belongs to the in-plane deformation vibration of hydroxyl groups; the stretching vibration of hydrogen and oxygen of carboxylic acid (2500-3300cm -1 ); free hydroxyl group (3650-3610cm -1 These three hydrophilic groups have good hydrophilicity and can serve as channels connecting the inside and outside of the filler, allowing nutrients to be released. At the same time, they will also improve the water holding capacity of the filler itself, which is conducive to maintaining a good microbial environment.

[0100] Example 10-12: Waste Gas Purification Method Using Nutrient Slow-Release Biofiller

[0101] Example 10

[0102] The present invention provides a waste gas purification method based on nutrient slow-release biological filler. The method of the present invention is implemented in a biological waste gas purification device. Figure 7The device for biological waste gas purification of the present invention includes a biotrickling filter 5, a liquid diversion device 7, a spray device and a bioreactor 10. Four air holes 3 are respectively provided on the side wall of the biotrickling filter 5 from bottom to top, wherein the bottom air hole is an air inlet, and a gas flow meter 2 is provided in the pipeline before the air intake, and air intake is achieved at the air inlet 1 of the gas flow meter. The two middle air holes on the side wall of the biotrickling filter 5 are normally closed air holes, which are sealed with a water stop clamp 4. The two middle normally closed air holes serve as the air outlet when measuring the purification effect of different packing layers. The uppermost air hole of the four air holes 3 is normally open as the air outlet, and the air holes are all transported by hoses.

[0103] The bio-trickling filter 5 is made of organic glass and has three layers of packing inside. Each packing layer is supported by an organic glass filter screen with a diameter of 98 mm and a filter hole diameter of 3 mm. The nutrient slow-release filler and modified polyurethane sponge filler are tightly stacked in layers on the filter screen, and each packing layer is 10 cm high. The same organic glass filter screen is installed at the bottom of the tower body of the bio-trickling filter 5, and the circulating liquid in the tower is introduced into the circulating liquid holding tank 8 through a pipe at the bottom.

[0104] The liquid diversion device 7, the structural diagram of which is shown in FIG. Figure 8 The liquid diversion device includes an inlet pipe 11, which is connected to a plurality of diversion pipes 12 oriented in different directions on the lower periphery of the inlet pipe 11. Each diversion pipe 12 is connected to a plurality of branch pipes 13 oriented in different directions below. In this embodiment, the diversion pipes 12 are main diversion rods, and the branch pipes are sub-diversion rods. Adjacent diversion pipes 12 are connected and fixed by fixing wires 14. The inlet pipe is a silicone tube.

[0105] The liquid diversion device 7 will first divert the liquid delivered by the peristaltic pump 9 to the diversion tube 12, i.e. the main diversion rod 12, and then drain it to the branch tube, i.e. the sub-diversion rod 13 through the diversion tube 12 to complete the uniform diversion of the liquid. The material, size and quantity of the diversion tube, i.e. the main diversion rod 12 and the branch tube, i.e. the sub-diversion rod 13 can be reasonably adjusted according to actual conditions, and there is no fixed requirement. The manufacturing method of the liquid diversion device 7 includes, first, cross-cutting the silicone tube into four petals, using waterproof glue to fix the heads of four wooden columnar main diversion rods against each other and respectively on the four-petal silicone tube, secondly, using waterproof glue to fix the heads of several wooden sub-diversion rods against each other at the tail of the main diversion rod, the size of the sub-diversion rod should generally be smaller than the main diversion rod, and finally, using iron wire to connect the four main diversion rods in pairs to play a supporting and fixing role, and the iron wire should be bent upward. The dimensions of the main and sub-diverter rods should be determined based on the actual space available. The dimensions of the main and sub-diverter rods used in this patent are 5 cm long and 0.5 cm in diameter, and 1.5 cm long and 0.15 cm in diameter, respectively. Each main diverter rod holds four sub-diverter rods, and the rods can be made of any material. The liquid diverter device ensures that the circulating liquid drips dispersedly, avoiding the problem of traditional filters where only the liquid drips in the center and the liquid is unevenly distributed.

[0106] The spraying device consists of a circulating liquid holding tank 8, a peristaltic pump 9, and a silicone tube. During spraying, the peristaltic pump 9 extracts the nutrient solution from the circulating liquid holding tank 8 and delivers it to the top of the biotrickling filter 5 through the silicone tube. The circulating liquid then flows through the packing inside the tower, flows out from the bottom of the tower, and re-enters the circulating liquid holding tank 8, completing a cycle.

[0107] Except for the bioreactor, nutrient-slow-release biological filler, and modified polyurethane sponge, the above-mentioned devices are all conventional equipment in this field and can be purchased on the market; the bioreactor 10 only needs an external aeration head and an air pump to complete the cultivation and acclimation during the cultivation and acclimation stages, and does not need to be connected to a biological trickling filter; the bioreactor 10 can exchange positions with the circulating liquid holding tank 8 during the filler biofilm formation stage, and then exchange positions with the circulating liquid holding tank 8 after sludge discharge.

[0108] The waste gas purification method based on nutrient slow-release biological filler in this embodiment includes the following steps:

[0109] Step 1: prepare a nutrient sustained-release biological filler; this example adopts the preparation of Example 1.

[0110] Step 2: Prepare the modified polyurethane sponge filler; this embodiment adopts the preparation of Example 3.

[0111] Step three, prepare the culture nutrient solution and the acclimation nutrient solution, culture and acclimate the activated sludge in the bioreactor; in this embodiment, the sludge comes from the sludge in the secondary sedimentation tank of the sewage treatment plant. The activated sludge includes two stages, culture and acclimation, and two different nutrient solutions are used to provide nutrition for the microorganisms. The difference is that glucose is added to the nutrient solution during the culture stage, and the microorganisms multiply rapidly with glucose as the only carbon source; during the acclimation stage, the nutrient solution does not contain glucose, and the target pollutant is used as the only carbon source to gradually replace glucose, and the adapted strains of the target pollutants are screened and further expanded. During the culture and acclimation stages, 5% of the sludge supernatant needs to be replaced with fresh nutrient solution every day, and during the acclimation stage, 0.1% of the liquid target pollutant needs to be added after the replacement. The specific method is: first culture the sludge for 13 days, during which time it is aerated for 12 hours every day, and the supernatant after the sludge is precipitated is replaced with fresh culture nutrient solution every day, and the replacement amount is 5% of the supernatant volume; then acclimate the sludge for 8 days, during which time it is aerated for 12 hours every day, and the supernatant after the sludge is precipitated is replaced with fresh acclimatization nutrient solution every day, and the replacement amount is 5% of the supernatant volume, and after the replacement, 0.1% of the supernatant volume of the liquid target pollutant, i.e., analytical grade toluene, with a toluene content ≥99.5% and a density (20°C) of 0.865-0.869 g / mL, is added.

[0112] The fresh culture nutrient solution in this step is a newly configured culture nutrient solution, rather than a recycled culture nutrient solution, and the fresh acclimation nutrient solution is a newly configured acclimation nutrient solution, rather than a used acclimation nutrient solution.

[0113] The culture nutrient solution contains the following components in concentrations: glucose 0.3 g / L, urea 0.05 g / L, K2HPO4 0.15 g / L, MgSO4 0.225 g / L, CaCl2 0.275 g / L, FeSO4 0.025 g / L, and the rest is deionized water; the acclimation nutrient solution contains the following components in concentrations: NH4Cl 0.3 g / L, MgCl2 0.1 g / L, CaCl2 0.1 g / L, K2HPO4 0.5 g / L, NaH2PO4 0.5 g / L, MnSO4 0.3 g / L, CuSO4 0.01 g / L, ZnSO4·7H2O 0.01 g / L, FeSO4·7H2O 0.01 g / L, and the rest is deionized water.

[0114] In this step, the activated sludge is cultivated and domesticated in the bioreactor 10. The bioreactor 10 is equipped with an aeration head and an air pump and does not need to be connected to a biological trickling filter.

[0115] Step 4: The modified polyurethane sponge filler from steps 1 and 2 is loaded into the biological trickling filter, which is provided with three layers of filler. In this embodiment, the specific structure of the biological trickling filter 5 is that the inner diameter of the biological trickling filter is 10 cm and the height is 150 cm. The nutrient slow-release biological filler and the modified polyurethane sponge filler are layered into the filler layer. Each filler layer is supported by an organic glass filter screen. The filler is tightly stacked on the filter screen. The volume of each filler layer is 785 cm. 3 , height 10cm, adjacent packing layers are spaced 10cm apart. When packing into the trickling filter, each layer should be densely packed to avoid airflow escaping from large gaps, which would affect the removal efficiency.

[0116] Step 5: Inject the activated sludge prepared in Step 3 into the biotrickling filter, allowing it to submerge all three layers of packing for 48 hours. Aerate for 12 hours every 12 hours, and drain the activated sludge from the bottom of the biotrickling filter after 48 hours. Microbial biofilm formation is performed on the surface of the modified polyurethane sponge packing.

[0117] In this step, bioreactor 10 is connected to biotrickling filter 5 and transported to the top of the filter via a silicone tube. The biomass is then discharged from the top of the filter body, submerging all three layers of packing. A rapid sludge removal method, coupled with continuous introduction of the target waste gas, is employed to allow microbial biofilm formation on the surfaces of the nutrient-slow-release biofiller and modified polyurethane sponge packing. Biofilm formation is considered successful when the purification efficiency consistently exceeds 80%, allowing the target waste gas to be purified.

[0118] Step 6: drip the domesticated nutrient solution from step 3 into the top of the bio-trickling filter and let it flow out from the bottom of the filter to realize the circulation of domesticated nutrient solution; during the biofilm formation period, use a peristaltic pump to drip the nutrient solution, i.e., domesticated nutrient solution, into the top of the bio-trickling filter and let it flow out from the bottom of the filter every day to realize the circulation of nutrient solution. Spray the nutrient solution for 12 hours every day at a spraying rate of 0.3L / h. During the waste gas purification period of biofilm formation, use a peristaltic pump to drip the circulating liquid into the top of the bio-trickling filter and let it flow out from the bottom of the filter every day to realize the circulation of the liquid-gas ratio (volume ratio 0.0001)

[0119] In this step, the circulating nutrient solution holding tank 8 contains the acclimated nutrient solution (circulating liquid), the bioreactor 10 is replaced with the circulating nutrient solution holding tank 8 and connected to the bio-trickling filter 5, and is pumped into the bio-trickling filter by the peristaltic pump 9.

[0120] Step 7: The waste gas enters the bottom of the biotrickling filter and is discharged from the top of the tower after being treated by three layers of packing. The waste gas to be treated is introduced from the bottom of the tower, and the concentration range of the waste gas to be treated is 180-230 mg / m 3 The intake air flow rate is 200 L / h. The ratio of the circulating liquid flow rate to the intake air flow rate of the waste gas to be treated is 0.001.

[0121] The present invention not only combines the characteristics of traditional biotrickling filters, such as low cost, environmental friendliness, and the ability to treat atmospheric low-concentration waste gas, but also reduces biofilm formation time, reduces the use of circulating nutrient solution, and increases system stability. Compared with traditional packed biotrickling filters, the present invention has a higher removal efficiency.

[0122] Example 11

[0123] The difference between this embodiment and embodiment 10 is that the modified polyurethane sponge filler of embodiment 4 is used in step 2 of this embodiment.

[0124] In step three, the sludge is first cultured for 10 days, during which time it is aerated for 12 hours every day. The supernatant after the sludge sedimentation is replaced with fresh culture nutrient solution every day, and the replacement amount is 5% of the supernatant volume; the sludge is then acclimated for another 10 days, during which time it is aerated for 12 hours every day.

[0125] In step seven, waste gas enters the bottom of the biotrickling filter, passes through three layers of packing, and exits the top. The treated waste gas is introduced at a flow rate of 80 L / h. The ratio of circulating liquid flow to treated waste gas flow is 0.002.

[0126] Example 12

[0127] The difference between this example and Example 10 is that the modified polyurethane sponge filler of Example 3 was used in step 1 of this example. In step 2, the sludge was first cultured for 15 days, during which time it was aerated daily for 7 hours. The supernatant after sludge sedimentation was replaced daily with fresh culture nutrient solution at a replacement volume of 5% of the supernatant volume. The sludge was then acclimated for another 7 days, during which time it was aerated daily for 12 hours.

[0128] In step seven, waste gas enters the bottom of the biotrickling filter, passes through three layers of packing, and exits the top. The treated waste gas is introduced from the bottom of the filter at a flow rate of 500 L / h. The ratio of the circulating liquid flow rate to the treated waste gas flow rate is 0.0005.

[0129] Test Example 1

[0130] The modified polyurethane sponge filler of the present invention can improve the efficiency of biofilm formation, and the biofilm formation time is tested. The purification ability of the process of Example 10 for toluene is tested.

[0131] The biological trickling filter tower has an inner diameter of 10 cm and a height of 150 cm. It includes three layers of packing, each layer is 10 cm high, and different packing layers are spaced 10 cm apart. The waste gas test gas enters the tower from the bottom air inlet, is filtered through the three layers of packing, and is discharged from the top air outlet. In order to compare the strengthening effects of the nutrient slow-release biological filler and the modified polyurethane sponge biological filler, the ordinary polyurethane sponge filler tower was used as the control group in the experiment, and the biological trickling filter tower composed of the nutrient slow-release biological filler and the modified polyurethane sponge biological filler of the present invention was used as the experimental group. The method of rapid sludge discharge-continuous introduction of toluene was used for film formation, and the inlet concentration of the two towers was controlled to be in the range of 180-230 mg / m 3 The air flow rate was 200 L / h. During the biofilm formation period, the nutrient solution was sprayed for 12 hours daily. The nutrient solution was the acclimatization nutrient solution, and the spraying rate was 0.3 L / h. Biofilm formation was considered successful when the toluene removal efficiency was greater than 80%.

[0132] On the fourth day of biofilm formation, the nutrient slow-release biofiller achieved a removal efficiency of 86.1%, which steadily increased to over 95% over the next 10 days. The control group, using a conventional polyurethane sponge packing, achieved a removal efficiency of 83.6% on the 13th day of biofilm formation, and this efficiency increased to 87.3% on the 14th day. This indicates that the combination of nutrient slow-release biofiller and modified polyurethane sponge biofiller outperformed conventional polyurethane sponge packing in terms of biofilm formation time.

[0133] Test Example 2

[0134] The difference from Test Example 1 is that after the biofilm is successfully formed, the toluene inlet concentration of the two towers is controlled to be 380-400 mg / m 3 .

[0135] By measuring toluene gas concentrations at the inlet and outlet, the researchers found that on the first day of concentration changes, the toluene removal efficiency of the control group dropped from 89.7% to 41.8%, while that of the experimental group dropped from 95.3% to 67.1%. After continued testing, the toluene removal efficiency of the control group recovered to 83.9% on the sixth day, and to 91.3% on the fourth day.

[0136] Test Example 3

[0137] The difference from Test Example 1 is that after the film is successfully formed, the toluene inlet concentration of the two towers is controlled to be 80-140 mg / m 3 .

[0138] By testing the toluene gas concentration at the air inlet and outlet, it was found that on the first day of changing the concentration, compared with the toluene purification efficiency of Test Example 1, the toluene purification efficiency of the control group and the experimental group did not change significantly and was slightly improved, with removal efficiencies of 90.4% and 96.2%, respectively; after a week of data testing, it was found that the toluene purification efficiency of the control group and the experimental group was stable at 93.6% and 98%, and the toluene purification efficiency of the experimental group could sometimes reach 100%. Under the condition of low toluene concentration, the purification efficiency of the two towers was improved.

[0139] It can be seen that the biotrickling filter tower composed of nutrient slow-release biological filler and modified polyurethane sponge filler can show higher stability when dealing with fluctuations in exhaust gas concentration, and its recovery time is also faster than that of the ordinary polyurethane sponge filler tower.

[0140] Test Example 4

[0141] The difference from Test Example 1 is that after the film formation is successful, the toluene inlet flow rate of the two towers is controlled to be increased to 300 L / h.

[0142] By measuring toluene gas concentrations at the inlet and outlet, we found that on the first day of changing the flow rate, the toluene removal efficiency of the control group dropped from 90.2% to 57.9%, while that of the experimental group dropped from 93.4% to 71.5%. After continuous testing, the toluene removal efficiency of the control group recovered to 85.6% on the third day, and to 93.3% on the second day.

[0143] It can be seen that the biotrickling filter tower composed of nutrient slow-release biological filler and modified polyurethane sponge filler can also show higher stability and faster recovery time when dealing with exhaust gas flow fluctuations.

[0144] Test Example 5

[0145] For the process of Example 8, only steps 1, 2, 4, and 7 are used. This example does not require the bioreactor 10, circulating nutrient solution 8, or peristaltic pump 9. This example does not require the cultivation and acclimation of activated sludge within the bioreactor, biofilm formation, or circulation of the acclimation nutrient solution. The toluene adsorption capacity of the above process was tested.

[0146] The toluene mixed gas enters the tower from the bottom air inlet, is filtered through three layers of packing, and is discharged from the top air outlet. The inlet concentration of the toluene mixed gas ranges from 180-230 mg / m 3 The air flow rate is 200 L / h, and the toluene concentration at the air inlet and outlet of the biofilter is measured every 1 hour.

[0147] The experiment lasted for 13 hours, during which the maximum adsorption capacity for toluene reached 57% at 1 hour. After that, the adsorption capacity gradually decreased with each hour. At the 13th hour, the adsorption capacity was almost gone, indicating that the adsorption saturation state for toluene was reached.

[0148] Under the same conditions, an adsorption experiment of toluene mixed gas by ordinary polyurethane sponge filler was also carried out. The experimental results showed that ordinary polyurethane sponge filler did not show adsorption performance for toluene.

[0149] At present, the technical solution of the present invention has been put into pilot production, that is, a small-scale experiment before the product is put into large-scale mass production; after the pilot production was completed, a user usage survey was carried out on a small scale, and the survey results showed that user satisfaction was high; now preparations have been started for the formal production and industrialization of the product (including intellectual property risk warning surveys).

[0150] The above-described embodiments are preferred embodiments of the present invention, but are not exhaustive of the feasible implementations of the present invention. For those skilled in the art, various improvements made without departing from the spirit and essence of the present invention should be considered to be included in the scope of protection of the present invention.

Claims

1. A waste gas purification method based on nutrient slow-release biological filler, characterized in that: The following steps are involved: Step 1, preparing a nutrient slow-release biological filler; Step 2, preparing modified polyurethane sponge filler; Step 3: preparing a culture nutrient solution and an acclimation nutrient solution, and culturing and acclimating the activated sludge in a bioreactor; Step 4: loading the nutrient slow-release biological filler prepared in Step 1 and the modified polyurethane sponge filler prepared in Step 2 as fillers of the filler layer into a biotrickling filter; Step 5: injecting the activated sludge acclimated in step 3 into the bio-trickling filter to form microbial biofilm on the surface of the filler; Step 6: dripping the domesticated nutrient solution from step 3 into the top of the bio-trickling filter and letting it flow out from the bottom of the filter to achieve a circulating flow of the domesticated nutrient solution; Step 7: The waste gas enters the bottom of the biotrickling filter and is discharged from the top of the tower after being treated by the packing layer; In step 1, the preparation process of the nutrient slow-release biological filler includes the following steps: S1, adding 9% polyvinyl alcohol and 4% sodium alginate to 100 ml of deionized water, mixing, and heating at a constant temperature of 95-130° C. with stirring until completely dissolved to obtain a gel solution; S2, adding 20% ​​citric acid-soluble fertilizer, 6% activated carbon powder, and 2% calcium carbonate powder to the gel solution, mixing evenly, and letting it stand for 1 hour to obtain a cross-linked suspension, and preparing a spherical slow-release filler with a controlled particle size of 1-2 cm; S3, preparing a saturated boric acid-2% calcium chloride solution, adjusting the pH value to between 5.0 and 5.3, placing the spherical slow-release filler into the saturated boric acid-2% calcium chloride solution, and cross-linking at 3-4° C. for 24 hours; S4, washing the cross-linked slow-release filler and air-drying it; In step 2, the preparation process of the modified polyurethane sponge filler includes the following steps: (1) preparing a modified suspension; (2) dipping the polyurethane sponge in the modified suspension so that the modified suspension is attached to the surface of the polyurethane sponge; (3) Immersing the loaded polyurethane sponge in a crosslinking solution, adjusting the pH of the crosslinking solution to 3.5-6.0, and crosslinking for 24 hours; (4) Washing the crosslinked polyurethane sponge with distilled water and air-drying it in a ventilated place; after air-drying, maintaining the polyurethane sponge at 165° C. for 1-10 minutes to obtain a modified polyurethane sponge filler.

2. The waste gas purification method based on nutrient slow-release biological filler according to claim 1, characterized in that: In step (1), the modified suspension comprises the following components, calculated by mass fraction: 3%-5% polyvinyl alcohol, 5%-7% sodium alginate, 3%-5% citrate-soluble fertilizer, 0.5%-1.5% activated carbon, 1%-3% calcium carbonate, and the balance is distilled water; the preparation method of the modified suspension is: heating polyvinyl alcohol and sodium alginate in distilled water until completely dissolved, adding activated carbon, stirring for 20-40 minutes, adding citrate-soluble fertilizer and calcium carbonate, stirring evenly, and standing for 2-3 hours to obtain the modified suspension.

3. The waste gas purification method based on nutrient slow-release biological filler according to claim 1, characterized in that: In step (2), the polyurethane sponge is immersed in the modified suspension for not less than 30 seconds, and the mass ratio of the modified suspension to the polyurethane sponge is: 10-15g of the modified suspension is attached to the surface of a 3cm×3cm×3cm cube of polyurethane sponge.

4. The waste gas purification method based on nutrient slow-release biological filler according to claim 1, characterized in that: In step (3), the cross-linking liquid is a saturated boric acid solution containing 2% calcium chloride, and the mass ratio of the cross-linking liquid to the loaded polyurethane sponge is: 10 loaded polyurethane sponges are immersed in every 600 mL of the cross-linking liquid, and the polyurethane sponge in each loaded polyurethane sponge is a 3 cm × 3 cm × 3 cm cube; the pH of the cross-linking liquid is adjusted to 4, and cross-linking is carried out for 24 hours; in step (4), high-temperature treatment is carried out at 165° C. for 3 minutes.

5. The waste gas purification method based on nutrient slow-release biological filler according to claim 1, characterized in that: In step 3, the process of acclimating the activated sludge is as follows: first, the sludge is cultivated for 10-15 days, during which time the sludge is aerated for 12 hours daily, and the supernatant after the sludge is precipitated is replaced with fresh culture nutrient solution every day, and the replacement amount is 5% of the supernatant volume; then the sludge is cultivated for 7-10 days, during which time the sludge is aerated for 12 hours daily, and the supernatant after the sludge is precipitated is replaced with fresh acclimation nutrient solution every day, and the replacement amount is 5% of the supernatant volume, and after the replacement, 0.1% of the supernatant volume of the liquid target pollutant is added; the culture nutrient solution contains the following components in concentrations: glucose 0.3g / L, urea 0.05g / L, K2HPO4 0.15g / L, MgSO4 0.225g / L, CaCl2 0.275g / L, FeSO4 0.025g / L, and the rest is deionized water; the acclimation nutrient solution contains the following components in concentrations: NH4Cl 0.3g / L, MgCl20.1g / L, CaCl20.1g / L, K2HPO4 0.5g / L, NaH2PO40.5g / L, MnSO40.3g / L, CuSO40.01g / L, ZnSO4·7H2O 0.01g / L, FeSO4·7H2O 0.01g / L, and the rest are deionized water.

6. The waste gas purification method based on nutrient slow-release biological filler according to claim 1, characterized in that: In step 4, a liquid diversion device is provided on the top of the biological trickling filter; the liquid diversion device comprises a liquid inlet pipe (11), which is connected to a plurality of diversion pipes (12) facing in different directions on the outer periphery of the lower portion of the liquid inlet pipe (11), and each of the diversion pipes (12) is connected to a plurality of branch pipes (13) facing in different directions below.

7. The waste gas purification method based on nutrient slow-release biological filler according to claim 1, characterized in that: In step five, the activated sludge acclimated in step three is injected into the bio-trickling filter tower so that it covers all the packing layers for 48 hours, and aerated for 12 hours every 12 hours. After 48 hours, the activated sludge is discharged from the bottom of the bio-trickling filter tower.

8. The waste gas purification method based on nutrient slow-release biological filler according to claim 1, characterized in that: In step 6, the circulating liquid for spraying on the packing surface in the biotrickling filter is sprayed into the filter every day for 12 hours; in step 7, the waste gas to be treated is introduced from the bottom of the filter, and the concentration of the waste gas to be treated is in the range of 80-500 mg / m 3 The ratio of the circulating liquid flow rate to the inlet flow rate of the waste gas to be treated is 0.0005-0.002:1.

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