Preparation method and application of filter element for purifying odor at tail end of hog house

Abstract

The invention relates to the field of piggery tail end odor pollution treatment, and discloses a piggery tail end odor purification filter element preparation method and application, the preparation method comprises the following steps: loading a photocatalyst on the surface of a filter element body to obtain a carrier, respectively inoculating 3-5 kinds of antagonism-free deodorization microorganisms into corresponding LB liquid culture mediums for activation and propagation, and carrying out purification on the LB liquid culture mediums to obtain the piggery tail end odor purification filter element. The preparation method comprises the following steps: preparing a bacterial solution, mixing the bacterial solution to obtain a corresponding bacterial solution, compounding all the bacterial solutions in proportion to obtain a compound bacterial solution, infiltrating a carrier in the compound bacterial solution, and carrying out biofilm formation at room temperature to obtain the filter element. After the photocatalyst on the surface is illuminated, some refractory pollutants can be decomposed into smaller intermediate products which are easier to utilize by microorganisms by utilizing light energy, a more suitable substrate is provided for the microorganisms, and the microorganisms can further thoroughly decompose the intermediate products into harmless substances such as carbon dioxide and water, so that the degradation effect is improved. Therefore, the overall degradation efficiency and degree of pollutants are improved.

Description

Technical Field

[0001] The present invention relates to the field of odor pollution control, and in particular to a method for preparing a filter element for odor purification at the end of a pig house and application thereof. Background Art

[0002] Pork plays a pivotal role in the global meat consumption structure. With the continuous growth of population and the steady improvement of living standards, the market demand for pork has shown a rigid upward trend. This trend has led to the continuous expansion of the pig farming industry, and large-scale farming has gradually become the mainstream model.

[0003] The pig farming process produces a large amount of harmful gases such as ammonia and hydrogen sulfide. These gases not only emit a pungent odor, seriously affecting the quality of life of surrounding residents, but also pose a great threat to the ecological environment and biological health. From an ecological perspective, excessive ammonia emissions lead to soil acidification and water eutrophication, destroying the balance of the natural ecosystem; from a health perspective, the surrounding residents are exposed to the polluted environment for a long time, and the incidence of respiratory diseases and cardiovascular diseases has increased significantly.

[0004] In the current era of advocating green development and sustainable development, how to effectively control gas pollution from pig farming has become a key issue that needs to be solved urgently. Under this situation, it is of great practical significance and urgency to carry out in-depth research on the control of gas pollution from pig farming and explore practical and feasible control strategies and technical means. This is not only related to the sustainable development of the pig farming industry, but also to the quality of life of the general public and the long-term protection of the ecological environment.

[0005] At present, odor control methods mainly focus on the source, process and end. Although the source and process can reduce the emission of pollutants, they cannot remove them fundamentally. The existing end-of-pipe deodorization in China is mainly based on water washing. Although it has a good effect on the removal of ammonia, if the wastewater generated by water washing is not properly treated, it may increase the burden of sewage treatment. In addition, the treatment effect on odorous substances that are difficult to dissolve in water (such as some VOCs and hydrogen sulfide) is poor, and it is impossible to achieve complete degradation. Summary of the invention

[0006] The purpose of the present invention is to overcome the problem of low odor purification efficiency in the prior art and provide a filter preparation method and application for odor purification at the end of a pig house. The method provided by the present invention combines photocatalysis and microbial purification, thereby effectively improving the odor degradation efficiency.

[0007] In order to achieve the above-mentioned object, the first aspect of the present invention provides a method for preparing a filter element for purifying odor at the end of a pig house, wherein the preparation method comprises: loading a photocatalyst on the surface of a filter element body to obtain a carrier;

[0008] 3 - 5 kinds of deodorizing microorganisms without antagonistic effects are respectively inoculated into the corresponding LB liquid medium for activation and amplification culture to obtain the corresponding bacterial solutions;

[0009] All the bacterial solutions are compounded in proportion to obtain a compound bacterial solution;

[0010] The carrier is immersed in the compound bacterial solution and subjected to film hanging at room temperature to obtain a filter element.

[0011] The second aspect of the present invention provides an application of the filter element prepared by the preparation method described in the first aspect of the present invention in odor purification.

[0012] In the present invention, a photocatalyst is loaded on the surface of the filter element body, and 3 - 5 kinds of deodorizing microorganisms without antagonistic effects are loaded inside it. The photocatalyst therein can use light energy to decompose some refractory pollutants into smaller intermediate products that are easier to be utilized by microorganisms, providing more suitable substrates for the microorganisms, and the microorganisms can further decompose these intermediate products completely into harmless substances such as carbon dioxide and water, thereby improving the overall degradation efficiency and degree of pollutants.

[0013] The filter element provided by the present invention is simple to manufacture, has a low replacement cost, can deeply degrade pollutants, has no secondary pollution, and has a wide application range. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 XRD patterns of mixed crystal titanium dioxide prepared at different temperatures;

[0015] Figure 2 Analysis of the degradation performance of the catalyst;

[0016] Figure 3 are the external views of the filter element body and the filter element prepared by the present invention;

[0017] Figure 4 are the scanning electron microscope images of the filter element body and the filter element prepared by the present invention;

[0018] Figure 5 is the change diagram of the dehydrogenase activity of microorganisms during the test;

[0019] Figure 6 is the change diagram of ammonia concentration in the test example. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] The following further describes the specific embodiments of the present invention in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not intended to limit the present invention.

[0021] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0022] The endpoints and any values within the ranges disclosed herein are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0023] In addition, the term "and / or" in the specification and claims is used to describe the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally represents an "or" relationship between the associated objects before and after.

[0024] The first aspect of the present invention provides a method for preparing a filter element for purifying the odor at the end of a pigsty. Among them, the method includes: loading a photocatalyst on the surface of the filter element body to obtain a carrier;

[0025] Connect 3-5 kinds of deodorizing microorganisms without antagonistic effects into the corresponding LB liquid medium for activation and amplification culture to obtain the corresponding bacterial solutions;

[0026] Mix all the bacterial solutions in proportion to obtain a compound bacterial solution;

[0027] Immerse the carrier in the compound bacterial solution and perform film hanging at room temperature to obtain a filter element.

[0028] Preferably, the preparation method of the photocatalyst includes: The preparation method of the photocatalyst includes: reacting anatase-rutile mixed crystal titania and g-C3N4 at 400-600 °C for 1.5-2 h. Among them, the anatase-rutile mixed crystal titania contains anatase phase and rutile phase. Among them, based on the total amount of the anatase-rutile mixed crystal titania, the amount of the rutile phase is 9-70 wt.%.

[0029] Preferably, based on the total amount of the mixed crystal titanium dioxide, the amount of the rutile phase is 35-40 wt.%.

[0030] Preferably, the mass ratio of the mixed crystal titanium dioxide to g-C3N4 is 1:0.4-0.6.

[0031] Preferably, the preparation method of the titanium dioxide includes:

[0032] Mix anhydrous ethanol and tetrabutyl titanate in a volume ratio of 1:1-1.5 to obtain solution A;

[0033] Mix anhydrous ethanol and ultrapure water in a volume ratio of 1:1-5 to obtain solution B;

[0034] Drop the solution A into the solution B, stir and react to obtain a gel containing TiO2, continue to age at room temperature for 1.5-2.5 h, then transfer the gel containing TiO2 to a reaction kettle, keep it at a constant temperature of 90°C-110°C for 1.5-2.5 h to obtain titanium dioxide;

[0035] Calcine the titanium dioxide at 500-650°C for 1.5-2.5 h to obtain the mixed crystal titanium dioxide.

[0036] Preferably, the annealing temperature is 600°C.

[0037] The present invention prepares TiO2 by combining the advantages of the sol-gel method and the hydrothermal method. This method saves 42% of the preparation time compared with the traditional sol-gel method and increases the yield by 92.5% compared with the traditional sol-gel method.

[0038] Furthermore, the mixed crystal titanium dioxide is obtained by heat treatment. The ratio of rutile to anatase in the mixed crystal TiO2 reaches the optimum, making the separation ability of photogenerated carriers the strongest. If the temperature is too high, the rutile content increases; if the temperature is too low, the anatase content increases. Neither too high nor too low temperature can reach the optimum.

[0039] The method provided by the present invention takes about 24 h for the preparation process (including 0.5 h for preparing the solution, 0.5 h for low-speed stirring, 2 h for aging, 2 h for keeping at a constant temperature of 100°C, 1 h for repeatedly washing with deionized water and ethanol, 12 h for drying, and 6 h for temperature rise and fall in the muffle furnace), and 12.64 g of catalyst can be obtained.

[0040] The traditional sol-gel method takes about 41 h (including 0.5 h for preparing the solution, 0.5 h for low-speed stirring, 21 h for aging, 1 h for repeatedly washing with deionized water and ethanol, 12 h for drying, and 6 h for temperature rise and fall in the muffle furnace), and 6.57 g of catalyst can be obtained. This method saves 42% of the preparation time compared with the traditional sol-gel method and increases the yield by 92.5% compared with the traditional sol-gel method.

[0041] Preferably, the deodorizing microorganisms include Klebsiella aerogenes, Acinetobacter lwoffii, and Bacillus velezensis. These microorganisms can be obtained through commercial purchase, experimental screening, or from a culture collection center. For example, Klebsiella aerogenes can be the strain with the preservation number CGMCC NO. 30271, Acinetobacter lwoffii can be the strain with the preservation number CGMCC NO. 30272, Bacillus velezensis can be the strain with the preservation number CGMCC NO. 30273, and Bacillus velezensis can also be the strain with the preservation number CGMCC NO. 30274.

[0042] Preferably, the preservation number of Klebsiella aerogenes is CGMCC NO. 30273, the preservation number of Acinetobacter lwoffii is CGMCC NO. 30272, and Bacillus velezensis includes the strain with the preservation number CGMCC NO. 30273 and the strain with the preservation number CGMCC NO. 30274. The compounding ratio of the bacterial solutions corresponding to the four strains is (0.9 - 1):(1 - 1.05):1:(1 - 1.05), and the most preferred is 0.95:1.02:1:1.01.

[0043] Preferably, the filter element body is made of sponge and / or polyester fiber cotton.

[0044] Photocatalytic reaction is a process in which photocatalytic materials release highly oxidizing active free radicals under light irradiation, degrade various large pollutant molecules into small pollutant molecules, and then decompose them into harmless small molecules. Currently, almost all photocatalytic materials are in powder form, and it is very difficult to separate and recover these fine powder materials from the reaction system, resulting in a large loss of photocatalytic materials. After the photocatalytic materials are loaded on a suitable carrier, the carrier can play a certain protective role for the photocatalytic materials, reduce the direct contact between the photocatalytic materials and the external environment, inhibit the occurrence of agglomeration and inactivation phenomena, and improve the stability and durability of the photocatalytic materials.

[0045] In the present invention, sponge is selected as the material of the filter element body. It has a soft texture and good flexibility, and can be processed into various shapes and sizes according to different application requirements, such as sheet shape, block shape, roll shape, etc. This processability enables it to be conveniently applied to different types of photocatalytic reactors to meet diverse actual usage scenarios. Most importantly, the porous structures of polyester fiber cotton and sponge are conducive to the passage of polluted gas, enabling the polluted gas to fully contact with the photocatalytic materials and achieve efficient degradation.

[0046] Preferably, the temperature for enlarged culture is 37 °C and the time is 24 h.

[0047] Preferably, the time for film hanging is 24 h.

[0048] The second aspect of the present invention provides an application of a filter element prepared by the preparation method described in the first aspect of the present invention in ammonia purification.

[0049] The odors in pig farms include components such as ammonia, hydrogen sulfide, volatile organic compounds (VOCs), and methanethiol, which are the main sources of odors. Among them, ammonia in particular has a strong pungent odor.

[0050] In the following examples and comparative examples, unless otherwise specified, reagents or instruments without indicating the manufacturer can be obtained as conventional products through commercial purchase. For those not specifying specific conditions in the examples, they are carried out according to conventional conditions or the conditions recommended by the manufacturer.

[0051] Ammonia removal rate test method: QB / T 2761-2006;

[0052] Odor removal rate test method: GB / T 14675-93.

[0053] Preparation Example 1

[0054] Mix absolute ethanol and tetrabutyl titanate at a volume ratio of 1:1.2 to obtain Solution A;

[0055] Mix absolute ethanol and ultrapure water at a volume ratio of 1:3 to obtain Solution B;

[0056] Drop the A solution into the B solution at a rate of 4 drops per second, stir and react for 0.5 h to obtain a gel containing TiO2. After continuing to age at room temperature (25 °C) for 2 h, transfer the gel containing TiO2 to a stainless steel reaction kettle with a polytetrafluoroethylene inner liner, keep it at a constant temperature of 100 °C for 2 h, cool and then centrifuge and sediment. Wash the precipitate with deionized water and ethanol repeatedly for 3 times, dry it in a blast drying oven at 100 °C, and obtain titanium dioxide after grinding.

[0057] Weigh 2 g of titanium dioxide, heat it at a heating rate of 10 °C / min to 540 °C and keep it for 2 h respectively. After the sample is cooled to room temperature, obtain mixed-crystalline titanium dioxide, denoted as T540.

[0058] Mix the T540 and g-C3N4, add them to 50 mL of ultrapure water at a mass ratio of 1:0.5, stir for 30 min, put it into a muffle furnace, heat it to 500 °C at a rate of 10 °C / min, and keep it for 2 h. After cooling, the required photocatalyst can be obtained.

[0059] Preparation Examples 2-5

[0060] It was carried out in the same manner as Preparation Example 1, except that the treatment temperature of titanium dioxide was different. The treatment temperatures of Preparation Examples 2-5 were 560 °C, 580 °C, 600 °C, and 620 °C, respectively, and the obtained mixed-crystalline titanium dioxides were denoted as T560, T580, T600, and T620, respectively.

[0061] The XRD patterns of the mixed-crystalline titanium dioxides prepared in Preparation Examples 1-5 are as Figure 1 shown. In the figure, T0 represents titanium dioxide without annealing treatment. It can be seen that the crystal form of the T0 catalyst (ordinary titanium dioxide) without temperature treatment is poor. At 2θ = 25.28, 37.80, 48.04, and 53.89, it coincides with the main characteristic peaks of anatase TiO2 (JCPDS no. 21-1272), indicating that the prepared T0 is anatase phase. The crystal form of the catalyst after temperature treatment is stronger than that of T0. It coincides with the main characteristic peaks of anatase TiO2 (JCPDS no. 21-1272) not only at 2θ = 25.28, 37.80, 48.04, 53.89, 55.06, 62.68, 70.31, and 75.03, but also at 2θ = 27.45, 36.09, 39.19, 41.23, 44.05, 54.32, 56.64, 62.74, 64.04, 65.48, 69.01, 69.79, 72.41, 74.41, and 76.51 with the main characteristic peaks of rutile TiO2 (JCPDS No. 21-1276). And with the increase of temperature, the rutile characteristic peaks gradually increase. The rutile content is calculated by the following formula:

[0062]

[0063] In the formula: X R : rutile content; I A : peak intensity of anatase at 2θ = 25.28°; I R : peak intensity of rutile at 2θ = 27.24°. The results are shown in Table 1.

[0064] Table 1 Rutile content of the catalyst

[0065]

[0066] Test Example 1

[0067] The photocatalysts prepared in Preparation Examples 1-5 were subjected to a degradation experiment. The experimental method is as follows:

[0068] An air generator is used to purify air into dry and clean air. The air flow rate is adjusted by a needle valve, and the adjusted air flow rate is detected by a flow meter. The air flow rate is controlled at about 0.5 L / min. At this time, the dry and clean air sends the ammonia gas volatilized from ammonia water to the photocatalytic reaction chamber. There are a sample inlet and a sample outlet at the front and back of the reaction chamber respectively. These two gas ports are connected to an INNOVA continuous detector at the same time to reflect the concentration change of ammonia gas before and after passing through the photocatalytic reaction. In the photocatalytic reaction chamber, a 300W xenon lamp is used to simulate sunlight, and a condensation reflux tube is installed outside the light source to reduce the influence of a large amount of heat generated by the light source during the reaction on the experimental results. The photocatalytic reaction tube is a quartz tube with a length of 6 cm and an inner diameter of 1 cm. The remaining tail gas will pass through the tail gas treatment device.

[0069] The results are as Figure 2 shown, where Figure 2 (a) is the degradation performance diagram of the catalyst, and 2(b) is the repeated use performance of the T600 catalyst. Figure 2 (c) is the pseudo-first-order reaction kinetics of the catalyst. Figure 2 (d) is the reaction constant of the catalyst. It can be seen that in the control group, the change in ammonia gas concentration is almost unchanged, indicating that ammonia gas itself is stable and not easily decomposed, and it also indicates that the device has no air leakage and can meet the experiment. It can be seen that the ammonia degradation rate first increases and then decreases with the increase of the catalyst annealing temperature. This is because with the increase of the annealing temperature, anatase TiO2 gradually transforms into rutile TiO2, and then a heterostructure is formed. This heterostructure is conducive to the separation of photo-generated carriers, thereby improving the performance of the photocatalytic material. However, the degradation performance of T620 is weaker than that of T600, which may be because the rutile content in T620 is too high, resulting in a disproportion and ultimately a decrease in activity.

[0070] To verify the repeated use performance of the T600 catalyst, after it degrades ammonia gas, it is placed in an 80°C oven and heated for 2 h, and then added to the reaction tube for ammonia degradation testing. As Figure 2 (b) shows, the results indicate that after being reused 5 times, T600 still has high activity.

[0071] The reaction kinetics of the catalyst is plotted with -In(C / C0) as the ordinate and time as the abscissa. It can be seen that the process of photocatalytic degradation of ammonia gas conforms to pseudo-first-order kinetics. Combining with (d), it can be seen that the reaction constants of T0, T540, T560, T580, T600, and T620 are 0.0034, 0.0061, 0.0094, 0.0098, 0.0144, and 0.0079 min -1 respectively, and the reaction constant of T600 is the highest, indicating the highest activity.

[0072] T600 has the best degradation activity because the ratio of rutile to anatase in the mixed-crystalline TiO2 (AR-TiO2) reaches the optimum, resulting in the strongest separation ability of photo-generated carriers. When the temperature is too high, the rutile content increases; when the temperature is too low, the anatase content increases. Neither high nor low temperature can achieve the optimum. Further experiments will be carried out with T600 in the future.

[0073] Preparation Example 6

[0074] Screen the deodorizing microorganisms and their compounding ratios required. The specific steps are as follows:

[0075] Four kinds of microorganisms with the highest deodorization rate were screened from the feces and sewage samples collected from the pig farm through enrichment culture in LB liquid medium, gradient dilution coating, and plate streaking separation and purification. They were identified as Klebsiella aerogenes (N1), Acinetobacter lwoffii (N2), Bacillus velezensis (N3), and Bacillus velezensis (N4). Enrichment culture in LB liquid medium, gradient dilution coating, and plate streaking separation and purification of bacterial strains are conventional operations in the art and will not be elaborated here.

[0076] LB liquid medium (g / L): 10.0 tryptone (Oxoid), 5.0 yeast extract powder (Oxoid), 5.0 sodium chloride (Xilong Scientific Co., Ltd.), and the balance is distilled water. LB solid medium is prepared by adding 15 g / L agar (Biofroxx) on the basis of the above formula.

[0077] The ammonia-degrading and deodorizing bacteria N1-N4 screened were subjected to an antagonistic experiment among strains by the filter paper method. The test strains were spread on the plate. The filter paper after high-pressure sterilization and drying was soaked in the bacterial liquid of other strains, and then the filter paper was taken out of the bacterial liquid with sterile forceps and pasted on the just-spread plate. Sterile water was used as a control. It was statically cultured at 37 °C in a biochemical incubator for 24 h, and the colony growth situation and the formation of inhibition zones were observed. The results are shown in Table 1. The four functional bacteria did not form inhibition zones with each other and had no antagonistic effect on each other, so they could be compounded.

[0078] Table 1 Antagonistic experiment among strains

[0079]

[0080] Note: "+" represents no antagonistic reaction, and "-" represents antagonistic reaction.

[0081] The selected strains were compounded by the response surface method to develop a composite microbial agent with ammonia-reducing and deodorizing functions. The ammonia-reducing and deodorizing effect tests were carried out according to 29 experimental schemes of microbial compounding. The results are shown in Table 2. The highest ammonia removal rate of the manure in the 17th test group was 77%, and there was no significant difference compared with the 1st - 2nd, 5th, 8th - 11th, 13th - 14th, 16th, 19th, 21st - 22nd, 24th, 27th - 29th groups (P>0.05), and it was significantly higher than the other groups (P<0.05); the highest odor removal rate of the manure in the 17th test group was 78.05%, and there was no significant difference compared with the 1st, 11th, 21st - 22nd, 24th groups (P>0.05), and it was significantly higher than the other groups (P<0.05).

[0082] Table 2 Ammonia-reducing and deodorizing effects of different strain compoundings

[0083]

[0084]

[0085] Note: Different lowercase letters in the superscripts of the same column of data indicate significant differences (P<0.05); the same lowercase letters in the superscripts indicate no significant differences (P>0.05).

[0086] Through the variance analysis of the models of the two response values of ammonia and odor removal rates, the regression equations R of the two models 2 >0.9. After verification, the optimal compounding volume ratios of N1 - N4 were 19.52%, 20.84%, 20.50% and 22.80% respectively (N1:N2:N3:N4 = 0.95:1.02:1:1.01), and the ammonia and odor removal rates were 74.58% and 73.25% respectively. These four strains have been preserved in the China General Microbiological Culture Collection Center. The corresponding preservation numbers of N1, N2, N3 and N4 are CGMCC NO.30273, CGMCC NO.30272, CGMCC NO.30273 and CGMCC NO.30274 respectively. Therefore, the corresponding strains can also be directly obtained from this preservation center. As a simplified method, the corresponding strains can also be directly obtained from this preservation center, activated and cultured, and then used directly, which can save the screening steps.

[0087] In the present invention, the best microbial species and their best compounding ratio for ammonia and odor removal were obtained by screening from the feces and sewage collected from pig farms, which can be used for the removal of ammonia and odor at the end of pig houses. The removal efficiency of ammonia and odor using only the screened microbial species and their best ratio is not less than 70%.

[0088] Example 1

[0089] Select a sponge with a size of 20×20 cm and 200 meshes, wash and dry it, and reserve the filter element body for later use;

[0090] After mixing the photocatalyst prepared in Preparation Example 1 with absolute ethanol at a mass-to-volume ratio of 1:50, spray it on the surface of the filter element body and air-dry it to obtain a carrier;

[0091] Select 4 kinds of microorganisms without antagonistic effects screened in Preparation Example 6 (the strains can also be directly obtained from the preservation center), inoculate the four strains N1-N4 into the corresponding LB liquid medium respectively, and perform shaking culture at 37 °C and 150 rpm for 24 h to obtain the corresponding bacterial solutions, which are respectively denoted as N1-N4;

[0092] Mix all the bacterial solutions N1-N4 according to a volume ratio of 0.95:1.02:1:1.01 to obtain a compound bacterial solution;

[0093] Immerse the carrier in the compound bacterial solution and let it stand for culture at room temperature (25 °C) for 24 h to obtain a filter element.

[0094] Figure 3 FIG. is the appearance diagram of the filter element body and the filter element prepared by the present invention. The filter element body (sponge) is on the left side, and the filter element prepared by the present invention is on the right side.

[0095] Figure 4 FIG. is the scanning electron microscope diagram of the filter element body and the filter element prepared by the present invention. The filter element body (sponge) is on the left side, and the filter element prepared by the present invention is on the right side. It can be seen that the photocatalytic material has been loaded in the porous structure of the sponge.

[0096] When ultraviolet light irradiates the photocatalyst on the surface, it can generate highly oxidizing free radicals, which can purify polluted gases and microorganisms. Since the photocatalytic material has antibacterial properties, in order to determine the activity of microorganisms in the filter element prepared by the present invention, it is necessary to conduct a microorganism activity test. The principle of the microorganism activity test is as follows:

[0097] Cell dehydrogenase is a class of enzymes that exist in cells and can catalyze oxidation-reduction reactions. It can catalyze most metabolic reactions in microorganisms, has the ability to activate hydrogen atoms, and plays a key role in the oxidation and phosphorylation processes of organic substances. The hydrogen acceptor in the living body receives the activated hydrogen atoms, thereby realizing the oxidation of substances. It is an indispensable enzyme for microorganisms to carry out metabolic reactions and obtain energy. Therefore, under specific conditions, the level of dehydrogenase activity can reflect the degradation ability of microorganisms to organic pollutants, and can also reflect the survival state of all microorganisms in the reaction process. The size of its activity can directly indicate the recovery degree of microorganism activity in the carrier and the degradation ability to intermediate products.

[0098] Based on this, the biological dehydrogenase activity during this test was also measured, and the specific results are as Figure 5 shown.

[0099] It can be seen from Figure 5 that at the initial stage, the dehydrogenase activity of microorganisms showed a downward trend. This is mainly because at the beginning of the reaction, the microorganisms were poisoned by various odors and had not yet adapted to the environment. In addition, the ultraviolet lamp irradiation caused the death of external microorganisms, temporarily reducing the biological activity. However, microorganisms have the characteristic of self-regulation. As the reaction continued, the inhibitory effect of various odors on microorganisms gradually weakened, and the intermediate products generated by the photocatalytic reaction were also transferred to the inside of the carrier. The microorganisms gradually adapted to the environment and obtained the carbon source required for growth, and their activity began to recover, with a significant increase in dehydrogenase activity. This indicates that after a period of time, the microorganisms inside the carrier are no longer damaged by the ultraviolet light source, the intermediate products in the photocatalytic stage diffuse to the inside of the carrier, and the microorganisms begin to play their functions. This phenomenon is consistent with the growth of the carrier biofilm.

[0100] The filter element prepared by the present invention, with a variety of microorganisms loaded, can coexist with the photocatalyst thereon and can exhibit good ammonia reduction and deodorization performance.

[0101] Test Example 2

[0102] Mix 90 mL of absolute ethanol and 10 mL of ultrapure water, put 1.35 g of BPET (polyethylene terephthalate) into them respectively, then add 2 g of catalyst respectively, shake at 37 °C for 2 h, weigh the mass of the BPET carrier after drying to calculate the loading amount, and then count the shedding rate after ultrasonic treatment for 30 min.

[0103] After testing, the catalyst loading amount of the present invention is 1.831 g / 78.5 cm 2 , compared with the traditional sol-gel method and hydrothermal method (0.436 g / 78.5 cm 2 ), the fixed amount of the catalyst is increased by 3.2 times. The shedding rate is 2.04% after ultrasonic treatment for 30 min.

[0104] Test Example 3

[0105] According to QB / T2761-2006, the purification performance of the filter element prepared in Example 1 was tested. The ammonia concentration in the test environment was 2.11 mg / m 3 , and the filter element provided by the present invention had an ammonia degradation rate of 92.4% for 1 m 3 within 24 h, and the ammonia degradation rate reached more than 70% after repeated degradation 5 times.

[0106] Furthermore, it was placed in the end odor purifier and monitored in the experimental shed for nearly 2 months. At the same time, the change in ammonia concentration in the control shed with the same ammonia concentration (without placing the filter element prepared by the present invention) was recorded. The results are as follows Figure 6 shown. It can be seen that the ammonia concentration in the experimental shed is significantly lower than that in the control shed, and the ammonia concentration always remains at a low level, while the ammonia concentration in the control shed even begins to rise after a period of time. The purification efficiency of the filter element provided by the present invention for ammonia always remains between 60% and 75%.

[0107] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any suitable combination of each specific technical feature. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods. But these simple modifications and combinations should also be regarded as the content disclosed by the present invention and all fall within the protection scope of the present invention.

Claims

1. A method for preparing a filter element for purifying odor at the end of a pig house, characterized in that: The preparation method comprises: loading a photocatalyst on the surface of a filter element body to obtain a carrier; 3-5 kinds of deodorizing microorganisms without antagonistic effects are respectively inoculated into corresponding LB liquid culture medium for activation and expansion to obtain corresponding bacterial liquid; Compounding all the bacterial solutions in proportion to obtain a compounded bacterial solution; The carrier is immersed in the composite bacterial solution, and a membrane is formed at room temperature to obtain a filter element.

2. The preparation method according to claim 1, wherein The preparation method of the photocatalyst comprises: reacting mixed crystal titanium dioxide and g-C3N4 at 400-600°C for 1.5-2h, wherein the mixed crystal titanium dioxide comprises anatase phase and rutile phase, wherein the amount of the rutile phase is 9-70wt.%, preferably 35-40wt.%, based on the total amount of the mixed crystal titanium dioxide.

3. The preparation method according to claim 2, wherein The mass ratio of the mixed crystal titanium dioxide and g-C3N4 is 1:0.4-0.

6.

4. The preparation method according to claim 2 or 3, wherein The preparation method of the mixed crystal titanium dioxide comprises: Anhydrous ethanol and butyl titanate are mixed in a volume ratio of 1:1-1.5 to obtain a solution A; Anhydrous ethanol and ultrapure water are mixed in a volume ratio of 1:1-5 to obtain a solution B; The A solution is added dropwise to the B solution, and the reaction is stirred to obtain a gel containing TiO2. After aging at room temperature for 1.5-2.5 hours, the gel containing TiO2 is transferred to a reaction kettle and kept at a constant temperature of 90°C-110°C for 1.5-2.5 hours to obtain titanium dioxide; annealing the titanium dioxide at 500-650° C. for 1.5-2.5 h to obtain the mixed crystal titanium dioxide; Preferably, the annealing temperature is 600°C.

5. The preparation method according to any one of claims 1 to 4, wherein: The deodorizing microorganisms include Klebsiella aerogenes, Acinetobacter loffei and Bacillus velez.

6. The preparation method according to claim 5, wherein: The temperature of the expansion culture is 37° C. and the time is 24 hours.

7. The preparation method according to claim 6, wherein: The film forming time is 24h.

8. The preparation method according to claim 6 or 7, wherein: The filter element body is sponge and / or polyester fiber cotton.

9. Use of a filter element prepared by the preparation method according to any one of claims 1 to 8 in odor purification.

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