A biological filler, a preparation method and application thereof

Abstract

The application discloses a kind of biological fillers and its preparation method and application, it is related to air pollution control field.The biological filler of the application includes the following components by weight: iron hydroxide-humic acid complex nanoparticles 5-10 parts, cyclodextrin 2-10 parts, diatomite 5 parts, biochar 5-20 parts, ceramic ball with through hole 20-35 parts, silicate 20-30 parts;It also includes at least one of calcium hydroxide and calcium salt, the total amount of calcium in calcium hydroxide and calcium salt is 0.035-0.090 parts by weight, which utilizes ceramic ball with through hole to realize slow release of humic acid and other components, and utilizes iron hydroxide-humic acid complex nanoparticles, so that Fe has very strong catalytic activity, effectively promotes the oxidation-reduction reaction of microbial organism, improves the purification efficiency of microorganism, and meanwhile, iron and humic acid combine to form a stable iron-humic acid catalytic system, which is not easy to lose.

Description

Technical Field

[0001] This invention relates to the field of air pollution control, specifically to a biological packing material, its preparation method, and its application. Background Technology

[0002] As public awareness of environmental protection gradually increases, the number of controlled odor indicators is gradually increasing, and emission limits for odor pollutants are becoming stricter. Biological deodorization technology is currently the most widely used deodorization technology. Packing materials play a crucial role in this technology, serving as both an important source of nutrition and support for microbial growth, and a medium for pollutant transfer; their performance directly affects the treatment effect of waste gas.

[0003] For odor control, the current challenge in biotechnology lies in finding a continuously efficient packing material that can both provide the nutrients needed for microbial growth and maintain a suitable microenvironment for the growth of highly efficient degrading bacteria. Commercially available biological packing materials can be categorized into inorganic, organic, and mixed packing materials based on their composition. Common inorganic packing materials, such as expanded clay, volcanic rock, perlite, and bamboo charcoal, do not contain the nutrients required for microbial growth and require periodic addition of nutrients during operation. Organic packing materials, such as bark, sawdust, peat, and organic fertilizer, have low mechanical strength, easily causing bed compaction and increasing operating resistance. Mixed packing materials, through proper compounding and full utilization of the advantages of each component, can compensate for the shortcomings of single-component packing materials and are currently the most widely used packing method. However, in practical applications, they suffer from problems such as difficulty in controlling the proportions, poor durability, and susceptibility to local collapse causing short-circuiting.

[0004] Currently, the development of biological packing materials in China is still in its initial stage. Research and development achievements are limited by factors such as cost and long-term operational intensity, failing to fully resolve the aforementioned problems of commercially available packing materials, and few have been successfully industrialized. Therefore, it is necessary to develop a packing material that can provide nutrients, possess good mechanical strength, and effectively and sustainably enhance deodorization. Summary of the Invention

[0005] Based on the deficiencies of existing technologies, the purpose of this invention is to provide a biological filler and its preparation method and application, so that the biological filler can provide nutrients, have good mechanical strength, and effectively improve the deodorization effect in a long-term manner.

[0006] To achieve the above objectives, in a first aspect, the present invention provides a biological filler comprising the following components in parts by weight: 5-10 parts of iron hydroxide-humic acid complex nanoparticles, 2-10 parts of cyclodextrin, 5 parts of diatomaceous earth, 5-20 parts of biochar, 20-35 parts of ceramsite with through-pores, and 20-30 parts of silicate; further comprising calcium hydroxide and / or calcium salts, wherein the calcium element in the calcium hydroxide and / or calcium salts is 0.035-0.090 parts by weight.

[0007] The biological packing material utilizes ceramic particles with through holes, which on the one hand stores a large amount of nutrients and can slowly release the nutrients needed for microbial growth during operation; on the other hand, it provides a rigid skeleton, which still has high mechanical strength after releasing nutrients, and can avoid problems such as flow interruption and local anaerobicness caused by the collapse of organic or mixed packing materials.

[0008] The bio-filler utilizes ferric hydroxide-humic acid complex nanoparticles to provide nano-iron. Compared to conventional iron oxide, nano-iron has a larger specific surface area, providing more active contact sites and exhibiting stronger catalytic activity. Furthermore, humic acid can promote Fe... 2+ / 3+ As an electron donor / acceptor, Fe participates in redox reactions, giving it stronger catalytic activity. Simultaneously, under the influence of microorganisms and acid / alkali conditions, the bio-filler can slowly release Fe and humic acid into the solution system, forming a humic acid-iron catalytic system on the filler surface and in the circulating liquid. This effectively promotes the redox reactions of the microorganisms. The humic acid-iron catalytic system can also absorb O2 generated during the degradation of H2S and VOCs (volatile organic compounds). - It contains reactive oxygen species (ROS) such as · and HO·, which alleviate the oxidative stress they cause and enhance the purification efficiency of microorganisms. The ferric hydroxide-humic acid complex is not easily lost, ensuring a stable iron-humic acid catalytic system in the biological packing material.

[0009] The biological filler can slowly release nutrients, maintain the microenvironment for bacterial growth for a long time, enhance biochemical reactions, and the preparation method is simple, which is convenient for process production and application.

[0010] Preferably, the average particle size of the iron hydroxide-humic acid complex nanoparticles is 5–100 nm.

[0011] Preferably, in the ferric hydroxide-humic acid complex nanoparticles, the mass ratio of ferric hydroxide to humic acid is 1:2 to 2:1. If the mass ratio of ferric hydroxide to humic acid is too high, the humic acid loading will be too low, resulting in poor long-term performance of the filler. If the mass ratio is too low, a large amount of humic acid will not be fixed on the surface of the ferric hydroxide and will easily be lost. When the mass ratio of ferric hydroxide to humic acid is within the above range, the humic acid can be fixed on the surface of the ferric hydroxide through complexation and has a high loading, giving the biological filler better sustained-release performance and long-term use performance.

[0012] Preferably, the ceramsite with through-holes satisfies at least one of conditions (I)-(II):

[0013] (I) The average diameter of the through holes in the ceramsite having through holes is 0.5 to 5.0 mm;

[0014] (II) The porosity of the ceramsite with through-holes is 70-85%.

[0015] If the diameter of the through hole is too large, the packing will have insufficient mechanical strength and be prone to breakage. At the same time, the complex of ferric hydroxide and humic acid will be easily lost, affecting performance. If the diameter of the through hole is too small, the complex of ferric hydroxide and humic acid will be difficult to load and the loading capacity will be low. When the width of the through hole is within the above range, the packing has good mechanical strength, the complex of ferric hydroxide and humic acid is easy to load and the loading capacity is stable. The slow-release performance and long-term service performance of the packing are superior.

[0016] Excessive porosity of ceramsite leads to poor water retention capacity of the packing material and insufficient contact between the flowing waste gas and the packing material and biofilm, which is not conducive to the removal of pollutants. Conversely, excessively low porosity of ceramsite results in excessive flow resistance of waste gas, making it prone to clogging, and also hinders microbial biofilm formation, affecting the treatment effect. When the porosity of ceramsite is within the above-mentioned range, the packing material has good water retention capacity, strong biological adhesion, and is not prone to clogging, which is conducive to the efficient treatment of waste gas.

[0017] Preferably, the cyclodextrin is at least one selected from α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin. More preferably, the cyclodextrin is β-cyclodextrin.

[0018] Cyclodextrin molecules have a hollow, three-dimensional ring structure. α-Cyclodextrin molecules have smaller cavities, allowing them to encapsulate only small molecules; γ-Cyclodextrin molecules have larger cavities, but higher production costs; while β-Cyclodextrin molecules have moderately sized cavities, making them suitable for a wider range of applications. Compared to α- and γ-cyclodextrins, using β-cyclodextrin results in higher odor removal rates and longer, sustainable, and stable operation of biological packing materials.

[0019] In some embodiments, the particle size of the ceramsite is 10-25 mm.

[0020] In some embodiments, the ceramsite also contains residual plant fibers, with the plant fiber content being less than 2% by mass.

[0021] Secondly, the present invention provides a method for preparing the above-mentioned biological packing material, comprising the following steps:

[0022] (1) Mix aggregate, water and plant fiber evenly, granulate, air dry, heat and fire, cool and anneal to obtain ceramsite with through holes;

[0023] (2) Dissolve soluble ferric salt in water to obtain ferric salt solution, keep the ferric salt solution at 80-95℃, add ammonia-ethanol-water solution, add humic acid solution while stirring, and then continue to keep warm, cool, filter, wash and dry to obtain black precipitate, which is ferric hydroxide-humic acid complex nanoparticles.

[0024] (3) Add cyclodextrin to water and stir until completely dissolved. Then add calcium oxide and continue stirring until completely dissolved to obtain sol A.

[0025] (4) Mix the nanoparticles of the iron hydroxide-humic acid complex obtained in step (2), diatomaceous earth, biochar and silicate evenly to obtain powder;

[0026] (5) Disperse the iron hydroxide-humic acid complex nanoparticles obtained in step (2) in water to obtain sol B;

[0027] (6) Soak the ceramic particles with through holes obtained in step (1) in the sol obtained in step (5), air dry them, and then soak them in the sol obtained in step (3). Then place them in a granulator and rotate them at a constant speed. Sprinkle the powder obtained in step (4) into the granulator multiple times evenly. Spray sol A before each powder is sprinkled, granulate, and obtain the biological filler.

[0028] The preparation method of the biological filler adopts a process of mixing and firing plant fiber and aggregate, which can form a continuous porous structure in the aggregate; the firing process adopts programmed heating and annealing, which is conducive to the stable molding of aggregate and enhances structural strength.

[0029] The preparation method of the bio-filler involves reacting ferric iron with ammonia in hot water to form nano-Fe(OH)3 micelles. The abundant carboxyl groups in humic acid coordinate with iron, fixing the humic acid onto the micelles. After filtration, washing, and drying, ferric hydroxide-humic acid complex nanoparticles are obtained. These nano-iron hydroxide-humic acid complex nanoparticles provide nano-iron, which, compared to conventional iron oxide, has a larger specific surface area, providing more active contact sites and stronger catalytic activity. Furthermore, humic acid can promote the catalytic activity of Fe... 2+ / 3+ As an electron donor / acceptor, Fe participates in redox reactions, giving it stronger catalytic activity. Simultaneously, under the influence of microorganisms and acid / alkali conditions, the bio-filler can slowly release Fe and humic acid into the solution system, forming a humic acid-iron catalytic system on the filler surface and in the circulating liquid. This effectively promotes the redox reactions of the microorganisms. The humic acid-iron catalytic system can also absorb O2 generated during the degradation of H2S and VOCs (volatile organic compounds). - It contains reactive oxygen species (ROS) such as · and HO·, which alleviate the oxidative stress they cause and enhance the purification efficiency of microorganisms. The ferric hydroxide-humic acid complex is not easily lost, ensuring a stable iron-humic acid catalytic system in the biological packing material.

[0030] When the reaction temperature between ferric iron and ammonia is too high or too low, nano-Fe(OH)3 micelles cannot be formed, thus preventing the formation of ferric hydroxide-humic acid complex nanoparticles. Replacing ammonia with a strong alkaline solution, such as sodium hydroxide or potassium hydroxide solution, also fails to form nano-Fe(OH)3 micelles. Only the use of ammonia ensures the formation of nano-Fe(OH)3 micelles, thereby forming ferric hydroxide-humic acid complex nanoparticles.

[0031] Preferably, the aggregate comprises the following components in parts by weight: 30-40 parts sludge, 30-40 parts fly ash, 5-10 parts phosphate rock, 5-10 parts clay ore, 1-5 parts magnesium hydroxide, 0.1-1 parts borate, 0.1-2 parts copper hydroxide, 0.1-1 parts molybdate, and 0.1-1 parts cobaltite.

[0032] The ceramsite uses sludge, fly ash, and other materials as aggregates, which is inexpensive and realizes the resource utilization of solid waste. At the same time, the added raw materials such as phosphate rock, magnesium hydroxide, borates, copper hydroxide, molybdates, and cobaltite can form corresponding slightly soluble salts, sparingly soluble salts, or oxides during the aggregate firing process. During use, inorganic nutrients such as P, Mg, B, Cu, Mo, and Co are slowly released through water solubility, acid-base reaction, and coordination, providing inorganic nutrients for microorganisms in a long-term and effective manner.

[0033] In some embodiments, the sludge used is dewatered sludge from plate and frame filter presses with a moisture content of 60-80%, containing calcium hydroxide and / or calcium salts, enabling the prepared biological packing material to slowly release calcium and achieve pH buffering. In other embodiments, the sludge preparation method includes the following steps: adding lime to activated sludge with a moisture content of 80%, mixing evenly to obtain sludge with a moisture content of 60-80%, wherein the mass of lime is 7-30% of the total mass of activated sludge and lime, and the subsequent water addition is adjusted accordingly.

[0034] Phosphate rock enables the biofill material to release phosphorus slowly. In some embodiments, the phosphate rock is selected from at least one of insoluble phosphates such as fluorapatite, chlorapatite, and hydroxyapatite.

[0035] In some embodiments, the clay mineral is selected from at least one of montmorillonite, kaolinite, vermiculite, etc., and its main component is aluminosilicate.

[0036] Magnesium hydroxide, when calcined, forms magnesium oxide and magnesium salts, enabling the biofiller to release magnesium in a slow-release manner.

[0037] Borates enable the biofill material to release boron in a slow-release manner. In some embodiments, the borate is selected from at least one of borazite, hydroborazite, borax, calcium borate, boromagnesia, etc.

[0038] Copper hydroxide enables the biological filler to release copper slowly.

[0039] Molybdates enable biofillers to release molybdenum in a slow-release manner. In some embodiments, the molybdate is selected from at least one of molybdenite, molybdenite, and molybdenum-copper ore.

[0040] Cobaltite enables biofillers to release cobalt in a slow-release manner.

[0041] Preferably, the volume ratio of the iron salt solution, ammonia-ethanol-water solution, and humic acid solution used in step (2) is 10:1:2-10, the mass concentration of soluble trivalent iron salt in the iron salt solution is 1-5%, the mass ratio of ammonia monohydrate, ethanol, and water in the ammonia-ethanol-water solution is 5-20:30:50-65, the mass concentration of humic acid in the humic acid solution is 1-5%, and the addition rate of the ammonia-ethanol-water solution is 10 mL / min / (1L iron salt solution).

[0042] Preferably, in step (3), the mass ratio of cyclodextrin, calcium oxide, and water used in sol A is 5-10:2-5:10-20, and the total weight of sol A accounts for 5-25% of the total weight of all raw materials used in the preparation of the biological filler. More preferably, in step (3), the total weight of sol A accounts for 20-25% of the total weight of all raw materials used in the preparation of the biological filler.

[0043] If the mass ratio of cyclodextrin used in step (3) is too large, it will be difficult to form the biological packing. If the mass ratio is too small, the cyclodextrin content in the biological packing will be too low and the effect will be insignificant. When the mass ratio of cyclodextrin, calcium oxide and water is 5-10:2-5:10-20, the biological packing is easy to form and the cyclodextrin content is moderate. In particular, when the cyclodextrin is β-cyclodextrin, the solubilizing effect on insoluble VOCs is more obvious, which can enhance the treatment performance of biological packing on insoluble VOCs.

[0044] If the total proportion of cyclodextrin, calcium oxide and water used in step (3) in all the raw materials for preparing biological packing is too large, it will lead to a significant reduction in the mechanical strength of the biological packing and make it easy to break and compact. If the proportion is too small, it will make it difficult to form the biological packing. When the proportion is in the range of 5-25%, the biological packing is easy to form and has high mechanical strength. In particular, when the proportion is in the range of 20-25%, it can effectively enhance the adsorption and degradation performance of the biological packing for insoluble VOCs.

[0045] Preferably, the preparation method satisfies at least one of conditions (a)-(k):

[0046] (a) In step (1), the average length of the plant fiber is 15-30 mm and the average diameter is 0.5-5.0 mm;

[0047] (b) In step (1), the plant fiber includes at least one of straw fiber, bamboo fiber, sugarcane fiber, and coconut shell fiber;

[0048] (c) In step (1), the volume ratio of the aggregate to the plant fiber is (4-5):1, and the weight of the water used is 5-20% of the total weight of the aggregate and the plant fiber.

[0049] (d) In step (1), the air drying operation is carried out in an environment of 15-30℃ and humidity ≤70% for 18-30 hours;

[0050] (e) In step (1), the specific steps of heating and firing include: heating to 200-300℃ at a heating rate of 5-20℃ / min, holding for 1-2 hours, then heating to 550-600℃ at a heating rate of 5-10℃ / min, holding for 10-30 minutes, then heating to 750-800℃ at a heating rate of 5-40℃ / min, holding for 10-30 minutes, and then heating to 950-1000℃ at a heating rate of 5-40℃ / min, holding for 10-30 minutes;

[0051] (f) In step (1), the specific steps of cooling annealing include: cooling to 700±10℃ at a cooling rate of ≤4℃ / min, then cooling to 400±10℃ at a cooling rate of ≤2℃ / min, and then naturally cooling to room temperature.

[0052] (g) In step (2), after adding the humic acid solution, continue to keep warm for 30 to 60 minutes;

[0053] (h) The mass ratio of the iron hydroxide-humic acid complex nanoparticles used in steps (4) and (5) is (1-2):1;

[0054] (i) The mass concentration of the ferric hydroxide-humic acid complex in the sol B obtained in step (5) is 1 to 10%;

[0055] (j) In step (6), the rotation speed of the uniform rotation is controlled at 25-35 r / min, and the turntable angle is controlled at 30-40°;

[0056] (k) In step (6), the specific steps for granulating the powder obtained in step (4) by repeatedly and evenly sprinkling it into the granulator are as follows: spray sol A before each sprinkling of powder, and sprinkle the powder into the granulator in 10-20 batches with an interval of 2 minutes.

[0057] Preferably, the granulation is followed by sieving to remove unqualified mud particles. In some embodiments, sieving removes unqualified mud particles with a particle size of less than 5 mm.

[0058] In some embodiments, the method for preparing plant fiber includes the following steps: crushing the plant fiber raw material to a particle size of 15-30 mm, drying it, and then molding it through physical kneading or chemical pyrolysis. In some embodiments, the plant fiber raw material is selected from at least one of straw, bamboo, sugarcane bagasse, coconut shell, etc.

[0059] In some embodiments, aggregates, water, and plant fibers are mixed in a mixer, such as a V-type mixer or a double cone mixer. In some embodiments, aggregates, water, and plant fibers are added to the mixer in 5-10 batches, with each batch containing the same proportion of aggregates, water, and plant fibers. The mixing speed is controlled at 10-20 r / min, and each batch is mixed for 8-20 minutes.

[0060] Thirdly, the present invention also provides the application of the biological packing material or the biological packing material prepared by the preparation method in odor treatment.

[0061] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0062] (1) The biological packing material of the present invention utilizes ceramic particles with through holes to store a large amount of nutrients and realize the slow release of nutrients. At the same time, it provides a rigid skeleton and still has high mechanical strength after releasing nutrients. This can avoid problems such as flow interruption and local anaerobicness caused by the collapse of organic packing or mixed packing, and ensure that the biological packing material has good durability.

[0063] (2) The biofiller of this invention utilizes ferric hydroxide-humic acid complex nanoparticles to provide nano-iron. Due to the large specific surface area of ​​nano-iron, its catalytic activity is very strong. At the same time, the humic acid enhances the catalytic activity of iron, effectively promoting the redox reaction of microorganisms. The ferric hydroxide-humic acid complex can also absorb O2 generated during the degradation of H2S, VOCs, etc. - The presence of reactive oxygen species such as · and HO· alleviates the oxidative stress caused by them, enhances the purification efficiency of microorganisms, and ensures that the iron hydroxide-humic acid complex is not easily lost, thus ensuring that the biological packing has a stable iron-humic acid catalytic system.

[0064] (3) The biological filler of the present invention can slowly release nutrients, maintain the microenvironment for bacterial growth for a long time, enhance biochemical reactions, and the preparation method is simple, which is convenient for process production and application. Detailed Implementation

[0065] To better illustrate the purpose, technical solution, and advantages of this invention, the invention will be further described below with reference to specific embodiments and comparative examples. The purpose of this description is to provide a detailed understanding of the invention, not to limit its scope. All other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of this invention. Unless otherwise specified, the experimental reagents and instruments involved in the implementation of this invention are all commonly used reagents and instruments. It should be noted that, unless otherwise specified, the process parameters used in the parallel comparative experiments provided below are all the same value.

[0066] Example 1

[0067] This embodiment provides a biological filler comprising the following components in parts by weight: 10 parts of ferric hydroxide-humic acid complex, 8 parts of β-cyclodextrin, 5 parts of diatomaceous earth, 20 parts of biochar, 20 parts of pore-forming ceramic particles, and 30 parts of silicate; it also includes calcium hydroxide and calcium salt, wherein the total calcium content of the calcium hydroxide and calcium salt is 0.090 parts by weight, and the ferric hydroxide-humic acid complex is in the form of nanoparticles. The average pore size of the pores in the pore-forming ceramic particles is 4.0 mm, and the porosity is 80%; in the ferric hydroxide-humic acid complex, the weight ratio of ferric hydroxide to humic acid is 1:1.

[0068] The preparation method of the biological packing material in this embodiment includes the following steps:

[0069] (1) Mix aggregate, water, and plant fiber evenly, granulate to form 15mm spherical mud particles, sieve to remove unqualified mud particles smaller than 5mm, air dry at 25℃ and 60% humidity for 12h, heat to 250℃ at a heating rate of 12℃ / min, hold for 1h, then heat to 580℃ at a heating rate of 7℃ / min, hold for 20min, then heat to 780℃ at a heating rate of 20℃ / min, hold for 20min, then heat to 980℃ at a heating rate of 20℃ / min, hold for 20min, then cool to 700℃ at a cooling rate of 3℃ / min, and then cool to 700℃ at a cooling rate of 1.5℃ / min. The temperature was lowered to 400℃ at a cooling rate of / min, and then naturally cooled to room temperature to obtain ceramsite with through holes. The volume ratio of aggregate to plant fiber was 4:1. The weight of water used was 15% of the total weight of aggregate and plant fiber. The plant fiber was straw fiber with an average fiber length of 20mm and an average fiber diameter of 4.0mm. The aggregate consisted of the following components by weight: 35 parts of plate and frame sludge (moisture content of 65%, containing 20wt% lime), 35 parts of fly ash, 10 parts of phosphate rock powder, 10 parts of clay ore powder, 5 parts of magnesium hydroxide, 1 part of borax, 2 parts of copper hydroxide powder, 1 part of molybdenum calcium ore, and 1 part of cobaltite powder.

[0070] (2) Dissolve 27 kg of ferric chloride hexahydrate in 100 L of water to obtain a 4.4 wt% ferric solution. Mix ammonia monohydrate, ethanol and water in a mass ratio of 15:30:55 to obtain an ammonia-ethanol-water solution. Keep the ferric solution at 90 °C and add 10 L of ammonia-ethanol-water solution at a rate of 1.0 L / min. Then add 40 L of 5% humic acid solution while stirring. Continue to keep warm, cool, filter, wash with water and air dry to obtain a black precipitate, which is the ferric hydroxide-humic acid complex nanoparticles.

[0071] (3) Add β-cyclodextrin to water and stir until completely dissolved. Then add calcium oxide and continue stirring until completely dissolved to obtain sol A, wherein the mass ratio of β-cyclodextrin, calcium oxide and water is 10:5:16.

[0072] (4) Mix the iron hydroxide-humic acid complex nanoparticles obtained in step (2), diatomaceous earth, biochar and silicate (P.Ⅱ42.5R silicate cement) evenly to obtain powder;

[0073] (5) Disperse the iron hydroxide-humic acid complex nanoparticles obtained in step (2) in water to obtain sol B with a mass concentration of 5%, wherein the mass ratio of the iron hydroxide-humic acid complex nanoparticles used in step (4) and this step is 1:1;

[0074] (6) Soak the ceramic particles with through holes obtained in step (1) in the sol B obtained in step (5), air dry them, and then soak them in the sol A obtained in step (3) (control the weight ratio of sol A in all raw materials of biological filler to 20%) for 5 minutes. Then place them in a granulator and rotate at a constant speed. Keep the rotation speed constant, control the rotation speed at 25 r / min, control the turntable angle at 30°, and evenly sprinkle the powder obtained in step (4) into the granulator every 2 minutes in 10 times to granulate, and obtain biological filler.

[0075] The mass ratio of the iron hydroxide-humic acid complex nanoparticles, diatomaceous earth, biochar, silicate, and the ceramsite with through-holes used in step (4) is 5:5:20:30:20.

[0076] The obtained biological packing material was loaded into a biofilter reactor. The packing material has a height of 190 mm and an effective volume of 1.2 L, and is used to treat simulated waste gas containing methanethiol. Methanethiol (nitrogen balance gas) is injected into the mixing tank via a mass flow meter, and air is introduced to dilute it before it is introduced into the reactor. The inlet gas concentration is 30–40 mg / m³. 3The gas residence time is approximately 15 seconds. The spray solution is pumped from the circulating water tank to the top of the reactor by a micro-pump. 1L of a mixed bacterial solution containing sulfur-oxidizing bacteria and highly efficient methanethiol-degrading bacteria (biomass ratio of the two bacteria: 1:1) with a microbial concentration of 1.0 × 10^8 cfu / L is added to the spray solution. The solution is then returned to the circulating water tank at the bottom of the reactor. The circulating water tank has a volume of 20L. Initially, 10L of tap water is added, and then tap water is periodically replenished to the original level. The removal rate of methanethiol by the reactor is observed and recorded. The removal rate of methanethiol by this biological filter reactor gradually increases, completing startup in 5 days, maintaining a removal rate above 95%, and can operate stably for more than 300 days.

[0077] Example 2

[0078] This embodiment provides a biological filler comprising the following components in parts by weight: 5 parts of ferric hydroxide-humic acid complex, 10 parts of β-cyclodextrin, 5 parts of diatomaceous earth, 5 parts of biochar, 35 parts of pore-forming ceramic particles, and 20 parts of silicate; it also includes calcium hydroxide and calcium salt, wherein the total calcium content of the calcium hydroxide and calcium salt is 0.035 parts by weight, and the ferric hydroxide-humic acid complex is in the form of nanoparticles. The pores in the pore-forming ceramic particles have an average pore size of 0.5 mm and a porosity of 70%; in the ferric hydroxide-humic acid complex, the weight ratio of ferric hydroxide to humic acid is 1:1.

[0079] The preparation method of the biological packing material in this embodiment includes the following steps:

[0080] (1) Mix aggregate, water and plant fiber evenly, granulate to form 15mm spherical mud particles, sieve to remove unqualified mud particles smaller than 5mm, air dry at 15℃ and 70% humidity for 12h, heat to 200℃ at a heating rate of 5℃ / min, hold for 1h, then heat to 550℃ at a heating rate of 5℃ / min, hold for 30min, then heat to 750℃ at a heating rate of 5℃ / min, hold for 30min, then heat to 950℃ at a heating rate of 5℃ / min, hold for 30min, then cool to 700℃ at a cooling rate of 4℃ / min, and then cool to 2℃ / min. The temperature was rapidly reduced to 400℃ and then allowed to cool naturally to room temperature to obtain ceramsite with through-holes. The volume ratio of aggregate to plant fiber was 4:1. The weight of water used was 5% of the total weight of aggregate and plant fiber. The plant fiber was straw fiber with an average fiber length of 15 mm and an average fiber diameter of 0.1 mm. The aggregate consisted of the following components by weight percentage: 40% plate and frame sludge (80 wt% water content, including 7 wt% lime), 30% fly ash, 5% phosphate rock powder, 5% clay ore powder, 1% magnesium hydroxide, 0.1% borates, 0.1% copper hydroxide powder, 0.1% molybdate, and 0.1% cobaltite powder.

[0081] (2) Dissolve 27 kg of ferric chloride hexahydrate in 100 L of water to obtain a 4.4 wt% ferric solution. Mix ammonia monohydrate, ethanol and water in a mass ratio of 15:30:55 to obtain an ammonia-ethanol-water solution. Keep the ferric solution at 95 °C and add 10 L of ammonia-ethanol-water solution at a rate of 1.0 L / min. Then add 40 L of 5 wt% humic acid solution while stirring. Continue to keep warm, cool, filter, wash with water and air dry to obtain a black precipitate, which is the ferric hydroxide-humic acid complex nanoparticles.

[0082] (3) Add β-cyclodextrin to water and stir until completely dissolved. Then add calcium oxide and continue stirring until completely dissolved to obtain sol A, wherein the mass ratio of β-cyclodextrin, calcium oxide and water is 10:5:20.

[0083] (4) Mix the iron hydroxide-humic acid complex nanoparticles obtained in step (2), diatomaceous earth, biochar and silicate (P.Ⅱ42.5R silicate cement) evenly to obtain powder;

[0084] (5) Disperse the iron hydroxide-humic acid complex nanoparticles obtained in step (2) in water to obtain sol B with a mass concentration of 1%, wherein the mass ratio of the iron hydroxide-humic acid complex nanoparticles used in step (4) and this step is 1:1.

[0085] (6) Soak the ceramic particles with through holes obtained in step (1) in the sol B obtained in step (5), air dry them, and then soak them in the sol A obtained in step (3) (control the weight ratio of sol A in all raw materials of biological filler to 25%) for 5 minutes. Then place them in a granulator and rotate at a constant speed. Keep the rotation speed constant, control the rotation speed at 30 r / min, control the turntable angle at 35°, and evenly sprinkle the powder obtained in step (4) into the granulator every 2 minutes in 15 times to granulate, and obtain biological filler.

[0086] The mass ratio of the iron hydroxide-humic acid complex nanoparticles, diatomaceous earth, biochar, silicate, and the ceramsite with through-holes used in step (4) is 2.5:5:5:20:35.

[0087] The obtained biological packing material was loaded into a biofilter reactor. The packing material has a height of 190 mm and an effective volume of 1.2 L, and is used to treat simulated waste gas containing methanethiol. Methanethiol (nitrogen balance gas) is injected into the mixing tank via a mass flow meter, and air is introduced to dilute it before it is introduced into the reactor. The inlet gas concentration is 30–40 mg / m³. 3The gas residence time is approximately 15 seconds. 1L of a mixed bacterial solution containing sulfur-oxidizing bacteria and highly efficient methanethiol-degrading bacteria (biomass ratio of the two bacteria: 1:1) with a microbial concentration of 1.0 × 10^8 cfu / L is added to the spray solution. This solution is pumped to the top of the reactor by a micro-pump in the circulating water tank for spraying. The spray solution returns to the circulating water tank at the bottom of the reactor. The circulating water tank has a volume of 20L. 10L of tap water is added at the start of operation, and then tap water is periodically replenished to the original level. The removal rate of methanethiol by the reactor is observed and recorded. The removal rate of methanethiol by this biofilter reactor gradually increases, completing startup in 5 days, maintaining a removal rate above 93%, and can operate stably for more than 280 days.

[0088] Example 3

[0089] This embodiment provides a biological filler comprising the following components in parts by weight: 10 parts of ferric hydroxide-humic acid complex, 10 parts of β-cyclodextrin, 5 parts of diatomaceous earth, 20 parts of biochar, 20 parts of porous ceramic particles, and 30 parts of silicate; it also includes calcium hydroxide and calcium salt, wherein the total calcium content of the calcium hydroxide and calcium salt is 0.090 parts by weight, and the ferric hydroxide-humic acid complex is in the form of nanoparticles. The porous ceramic particles have an average pore size of 5 mm and a porosity of 85%; in the ferric hydroxide-humic acid complex, the weight ratio of ferric hydroxide to humic acid is 1:1.

[0090] The preparation method of the biological packing material in this embodiment includes the following steps:

[0091] (1) Mix aggregate, water, and plant fiber evenly, granulate to form 15mm spherical mud particles, sieve to remove unqualified mud particles smaller than 5mm, air dry at 30℃ and 60% humidity for 12h, heat to 300℃ at a heating rate of 20℃ / min, hold for 1h, then heat to 600℃ at a heating rate of 10℃ / min, hold for 10min, then heat to 800℃ at a heating rate of 40℃ / min, hold for 10min, then heat to 1000℃ at a heating rate of 40℃ / min, hold for 10min, then cool to 700℃ at a cooling rate of 2℃ / min, then cool to 1℃ / min at a cooling rate of 1℃ / min. The temperature is reduced to 400℃ at a cooling rate of n, and then naturally cooled to room temperature to obtain ceramsite with through holes. The volume ratio of aggregate to plant fiber is 4:1. The weight of water used is 20% of the total weight of aggregate and plant fiber. The plant fiber is straw fiber with an average fiber length of 30mm and an average fiber diameter of 5.0mm. The aggregate includes the following components by weight percentage: 30% plate and frame sludge (60wt% water content, containing 30wt% lime), 40% fly ash, 10% phosphate rock powder, 10% clay ore powder, 5% magnesium hydroxide, 1% borate, 2% copper hydroxide powder, 1% molybdate, and 1% cobaltite powder.

[0092] (2) Dissolve 27 kg of ferric chloride hexahydrate in 100 L of water to obtain a 4.4 wt% ferric solution. Mix ammonia monohydrate, ethanol and water in a mass ratio of 15:30:55 to obtain an ammonia-ethanol-water solution. Keep the ferric solution at 95 °C and add 10 L of ammonia-ethanol-water solution at a rate of 1.0 L / min. Then add 40 L of 5 wt% humic acid solution while stirring. Continue to keep warm, cool, filter, wash with water and air dry to obtain a black precipitate, which is the ferric hydroxide-humic acid complex nanoparticles.

[0093] (3) Add modified iron-based β-cyclodextrin to water and stir until completely dissolved. Then add calcium oxide and continue stirring until completely dissolved to obtain sol A, wherein the mass ratio of β-cyclodextrin, calcium oxide and water is 10:2:10.

[0094] (4) Mix the iron hydroxide-humic acid complex nanoparticles obtained in step (2), diatomaceous earth, biochar and silicate (P.Ⅱ42.5R silicate cement) evenly to obtain powder;

[0095] (5) Disperse the iron hydroxide-humic acid complex nanoparticles obtained in step (2) in water to obtain sol B with a mass concentration of 10%, wherein the mass ratio of the iron hydroxide-humic acid complex nanoparticles used in step (4) and this step is 1:1.

[0096] (6) Soak the ceramic particles with through holes obtained in step (1) in the sol B obtained in step (5), air dry them, and then soak them in the sol A obtained in step (3) (control the weight ratio of sol A in all raw materials of biological filler to 20%) for 5 minutes. Then place them in a granulator and rotate at a constant speed. Keep the rotation speed constant, control the rotation speed at 35 r / min, control the turntable angle at 40°, and evenly sprinkle the powder obtained in step (4) into the granulator every 2 minutes in 20 times to granulate, and obtain biological filler.

[0097] The mass ratio of the iron hydroxide-humic acid complex nanoparticles, diatomaceous earth, biochar, silicate, and the ceramsite with through-holes used in step (4) is 5:5:20:30:20.

[0098] The obtained biological packing material was loaded into a biofilter reactor. The packing material has a height of 190 mm and an effective volume of 1.2 L, and is used to treat simulated waste gas containing methanethiol. Methanethiol (nitrogen balance gas) is injected into the mixing tank via a mass flow meter, and air is introduced to dilute it before it is introduced into the reactor. The inlet gas concentration is 30–40 mg / m³. 3The gas residence time is approximately 15 seconds. 1L of a mixed bacterial solution containing sulfur-oxidizing bacteria and highly efficient methanethiol-degrading bacteria (biomass ratio of the two bacteria: 1:1) with a microbial concentration of 1.0 × 10^8 cfu / L is added to the spray solution. This solution is pumped to the top of the reactor by a micro-pump in the circulating water tank for spraying. The spray solution returns to the circulating water tank at the bottom of the reactor. The circulating water tank has a volume of 20L. 10L of tap water is added at the start of operation, and then tap water is periodically replenished to the original level. The removal rate of methanethiol by the reactor is observed and recorded. The removal rate of methanethiol by this biofilter reactor gradually increases, completing startup in 5 days, maintaining a removal rate above 93%, and can operate stably for more than 280 days.

[0099] Example 4

[0100] This embodiment provides a biological packing material. Except for the ferric hydroxide-humic acid complex, where the mass ratio of ferric hydroxide to humic acid is 1:2, the biological packing material in this embodiment is identical to that in Example 1. The preparation method of the biological packing material in this embodiment is identical to that in Example 1, except that in step (2), the mass concentration of the ferric solution is 1%, the mass ratio of ammonia monohydrate, ethanol, and water in the ammonia-ethanol-water solution is 5:30:65, and the mass concentration of the humic acid solution is 5%.

[0101] The obtained biological packing material was loaded into a biofilter reactor. The packing material has a height of 190 mm and an effective volume of 1.2 L, and is used to treat simulated waste gas containing methanethiol. Methanethiol (nitrogen balance gas) is injected into the mixing tank via a mass flow meter, and air is introduced to dilute it before it is introduced into the reactor. The inlet gas concentration is 30–40 mg / m³. 3 The gas residence time is approximately 15 seconds. 1L of a mixed bacterial solution containing sulfur-oxidizing bacteria and highly efficient methanethiol-degrading bacteria (biomass ratio of the two bacteria: 1:1) with a microbial concentration of 1.0 × 10^8 cfu / L is added to the spray solution. This solution is pumped to the top of the reactor by a micro-pump in the circulating water tank for spraying. The spray solution returns to the circulating water tank at the bottom of the reactor. The circulating water tank has a volume of 20L. 10L of tap water is added at the start of operation, and then tap water is periodically replenished to the original level. The removal rate of methanethiol by the reactor is observed and recorded. The removal rate of methanethiol by this biofilter reactor gradually increases, completing startup in 5 days, maintaining a removal rate above 94%, and can operate stably for more than 280 days.

[0102] Example 5

[0103] This embodiment provides a biological packing material. Except for the ferric hydroxide-humic acid complex, where the mass ratio of ferric hydroxide to humic acid is 2:1, the biological packing material in this embodiment is identical to that in Example 1. The preparation method of the biological packing material in this embodiment is identical to that in Example 1, except that in step (2), the mass concentration of the ferric solution is 5%, the mass ratio of ammonia monohydrate, ethanol, and water in the ammonia-ethanol-water solution is 20:30:50, and the mass concentration of the humic acid solution is 1%.

[0104] The obtained biological packing material was loaded into a biofilter reactor. The packing material has a height of 190 mm and an effective volume of 1.2 L, and is used to treat simulated waste gas containing methanethiol. Methanethiol (nitrogen balance gas) is injected into the mixing tank via a mass flow meter, and air is introduced to dilute it before it is introduced into the reactor. The inlet gas concentration is 30–40 mg / m³. 3 The gas residence time is approximately 15 seconds. 1L of a mixed bacterial solution containing sulfur-oxidizing bacteria and highly efficient methanethiol-degrading bacteria (biomass ratio of the two bacteria: 1:1) with a microbial concentration of 1.0 × 10^8 cfu / L is added to the spray solution. This solution is pumped to the top of the reactor by a micro-pump in the circulating water tank for spraying. The spray solution returns to the circulating water tank at the bottom of the reactor. The circulating water tank has a volume of 20L. 10L of tap water is added at the start of operation, and then tap water is periodically replenished to the original level. The removal rate of methanethiol by the reactor is observed and recorded. The removal rate of methanethiol by this biofilter reactor gradually increases, completing startup in 5 days, maintaining a removal rate above 94%, and can operate stably for more than 280 days.

[0105] Example 6

[0106] This embodiment provides a biological packing material. Except for the ferric hydroxide-humic acid complex, where the mass ratio of ferric hydroxide to humic acid is 1:4, the biological packing material in this embodiment is identical to that in Example 1. The preparation method of the biological packing material in this embodiment is identical to that in Example 1, except that in step (2), the mass concentration of the ferric solution is 0.5%, the mass ratio of ammonia monohydrate, ethanol, and water in the ammonia-ethanol-water solution is 5:30:65, and the mass concentration of the humic acid solution is 5%.

[0107] The obtained biological packing material was loaded into a biofilter reactor. The packing material has a height of 190 mm and an effective volume of 1.2 L, and is used to treat simulated waste gas containing methanethiol. Methanethiol (nitrogen balance gas) is injected into the mixing tank via a mass flow meter, and air is introduced to dilute it before it is introduced into the reactor. The inlet gas concentration is 30–40 mg / m³. 3The gas residence time is approximately 15 seconds. The spray solution is pumped from the circulating water tank to the top of the reactor by a micro-pump. 1L of a mixed bacterial solution containing sulfur-oxidizing bacteria and highly efficient methanethiol-degrading bacteria (biomass ratio of the two bacteria: 1:1) with a microbial concentration of 1.0 × 10^8 cfu / L is added to the spray solution. The solution is then returned to the circulating water tank at the bottom of the reactor. The circulating water tank has a volume of 20L. Initially, 10L of tap water is added, and then tap water is periodically replenished to the original level. The removal rate of methanethiol by the reactor is observed and recorded. The removal rate of methanethiol by this biological filter reactor gradually increases, completing startup in 5 days, maintaining a removal rate above 92%, and can operate stably for more than 270 days.

[0108] Example 7

[0109] This embodiment provides a biological packing material. Except for the ferric hydroxide-humic acid complex, where the mass ratio of ferric hydroxide to humic acid is 4:1, the biological packing material in this embodiment is identical to that in Example 1. The preparation method of the biological packing material in this embodiment is identical to that in Example 1, except that in step (2), the mass concentration of the ferric solution is 5%, the mass ratio of ammonia monohydrate, ethanol, and water in the ammonia-ethanol-water solution is 20:30:50, and the mass concentration of the humic acid solution is 0.5%.

[0110] The obtained biological packing material was loaded into a biofilter reactor. The packing material has a height of 190 mm and an effective volume of 1.2 L, and is used to treat simulated waste gas containing methanethiol. Methanethiol (nitrogen balance gas) is injected into the mixing tank via a mass flow meter, and air is introduced to dilute it before it is introduced into the reactor. The inlet gas concentration is 30–40 mg / m³. 3 The gas residence time is approximately 15 seconds. 1L of a mixed bacterial solution containing sulfur-oxidizing bacteria and highly efficient methanethiol-degrading bacteria (biomass ratio of the two bacteria: 1:1) with a microbial concentration of 1.0 × 10^8 cfu / L is added to the spray solution. This solution is pumped to the top of the reactor by a micro-pump in the circulating water tank for spraying. The spray solution returns to the circulating water tank at the bottom of the reactor. The circulating water tank has a volume of 20L. 10L of tap water is added at the start of operation, and then tap water is periodically replenished to the original level. The removal rate of methanethiol by the reactor is observed and recorded. The removal rate of methanethiol by this biofilter reactor gradually increases, completing startup in 5 days, maintaining a removal rate above 92%, and can operate stably for more than 260 days.

[0111] Compared with the biological packing materials obtained in Examples 6 and 7, the biological packing materials obtained in Examples 1, 4 and 5 have a significantly higher removal rate of methanethiol and a significantly longer period of sustainable and stable operation.

[0112] Example 8

[0113] This embodiment provides a biological filler. Except for including 2 parts by weight of β-cyclodextrin, the biological filler in this embodiment is the same as in Example 1. The preparation method of the biological filler in this embodiment is the same as in Example 1, except that in step (5), the weight percentage of sol A in all raw materials of the biological filler is controlled to be 5%.

[0114] The obtained biological packing material was loaded into a biofilter reactor. The packing material has a height of 190 mm and an effective volume of 1.2 L, and is used to treat simulated waste gas containing methanethiol. Methanethiol (nitrogen balance gas) is injected into the mixing tank via a mass flow meter, and air is introduced to dilute it before it is introduced into the reactor. The inlet gas concentration is 30–40 mg / m³. 3 The gas residence time is approximately 15 seconds. 1L of a mixed bacterial solution containing sulfur-oxidizing bacteria and highly efficient methanethiol-degrading bacteria (biomass ratio of the two bacteria: 1:1) with a microbial concentration of 1.0×10^8 cfu / L is added to the spray solution. This solution is pumped to the top of the reactor by a micro-pump in the circulating water tank for spraying. The spray solution returns to the circulating water tank (20L volume) at the bottom of the reactor. Initially, 10L of tap water is added, and then tap water is periodically replenished to the original level. The removal rate of methanethiol by the reactor is observed and recorded. The removal rate of methanethiol by this biofilter reactor gradually increases, completing startup in 5 days, maintaining a removal rate above 85%, and can operate stably for more than 260 days.

[0115] Compared to Example 8, Example 1 has a significantly higher removal rate and a significantly longer continuous stable operation time because the weight ratio of sol A in all raw materials of biological filler is controlled within the range of 20-25%.

[0116] Example 9

[0117] This embodiment provides a biological packing material. Except for the use of γ-cyclodextrin, the biological packing material in this embodiment is identical to that in Example 1.

[0118] The obtained biological packing material was loaded into a biofilter reactor. The packing material has a height of 190 mm and an effective volume of 1.2 L, and is used to treat simulated waste gas containing methanethiol. Methanethiol (nitrogen balance gas) is injected into the mixing tank via a mass flow meter, and air is introduced to dilute it before it is introduced into the reactor. The inlet gas concentration is 30–40 mg / m³. 3The gas residence time is approximately 15 seconds. 1L of a mixed bacterial solution containing sulfur-oxidizing bacteria and highly efficient methanethiol-degrading bacteria (biomass ratio of the two bacteria: 1:1) with a microbial concentration of 1.0 × 10^8 cfu / L is added to the spray solution. This solution is pumped to the top of the reactor by a micro-pump in the circulating water tank for spraying. The spray solution returns to the circulating water tank at the bottom of the reactor. The circulating water tank has a volume of 20L. Initially, 10L of tap water is added, and then tap water is periodically replenished to the original level. The removal rate of methanethiol by the reactor is observed and recorded. The removal rate of methanethiol by this biofilter reactor gradually increases, completing startup in 5 days, maintaining a removal rate above 90%, and can operate stably for more than 280 days.

[0119] Compared to Example 9, Example 1, due to the use of β-cyclodextrin, has a significantly higher removal rate and a significantly longer continuous stable operating time.

[0120] Comparative Example 1

[0121] This comparative example provides a biological packing material. Except for the absence of humic acid, the biological packing material of this comparative example is identical to that of Example 1. Its preparation method is identical to the biological packing material of Example 1, except that humic acid solution is not used in step (2).

[0122] The obtained biological packing material was loaded into a biofilter reactor. The packing material has a height of 190 mm and an effective volume of 1.2 L, and is used to treat simulated waste gas containing methanethiol. Methanethiol (nitrogen balance gas) is injected into the mixing tank via a mass flow meter, and air is introduced to dilute it before it is introduced into the reactor. The inlet gas concentration is 30–40 mg / m³. 3 The gas residence time is approximately 15 seconds. 1L of a mixed bacterial solution containing sulfur-oxidizing bacteria and highly efficient methanethiol-degrading bacteria (biomass ratio of the two bacteria: 1:1) with a microbial concentration of 1.0 × 10^8 cfu / L is added to the spray solution. This solution is pumped to the top of the reactor by a micro-pump in the circulating water tank for spraying. The spray solution returns to the circulating water tank at the bottom of the reactor. The circulating water tank has a volume of 20L. 10L of tap water is added at the start of operation, and then tap water is periodically replenished to the original level. The removal rate of methanethiol by the reactor is observed and recorded. The removal rate of methanethiol by this biofilter reactor gradually increases. After 10 days of startup, the removal rate is maintained above 85%, and it can operate stably for more than 200 days.

[0123] Compared to Example 1, the biological packing material obtained in Comparative Example 1, which does not contain humic acid, has a significantly lower methanethiol removal rate and a significantly shorter time for sustainable and stable operation.

[0124] Comparative Example 2

[0125] This comparative example provides a biological packing material. Except for the absence of through-holes in the ceramic particles contained in this comparative example biological packing material, it is otherwise identical to that of Example 1. The preparation method, except for the absence of plant fibers in step (1), is otherwise identical to the preparation method of the biological packing material in Example 1.

[0126] The obtained biological packing material was loaded into a biofilter reactor. The packing material has a height of 190 mm and an effective volume of 1.2 L, and is used to treat simulated waste gas containing methanethiol. Methanethiol (nitrogen balance gas) is injected into the mixing tank via a mass flow meter, and air is introduced to dilute it before it is introduced into the reactor. The inlet gas concentration is 30–40 mg / m³. 3 The gas residence time is approximately 15 seconds. 1L of a mixed bacterial solution containing sulfur-oxidizing bacteria and highly efficient methanethiol-degrading bacteria (biomass ratio of the two bacteria: 1:1) with a microbial concentration of 1.0 × 10^8 cfu / L is added to the spray solution. This solution is pumped to the top of the reactor by a micro-pump in the circulating water tank for spraying. The spray solution returns to the circulating water tank at the bottom of the reactor. The circulating water tank has a volume of 20L. 10L of tap water is added at the start of operation, and then tap water is periodically replenished to the original level. The removal rate of methanethiol by the reactor is observed and recorded. The removal rate of methanethiol by this biofilter reactor gradually increases. After 10 days of startup, the removal rate is maintained above 70%, and it can operate stably for more than 100 days.

[0127] Compared to Example 1, the biological packing material obtained in Comparative Example 2 has a significantly lower methanethiol removal rate and a significantly shorter sustainable and stable operation time because the ceramic particles do not contain through-pores.

[0128] Comparative Example 3

[0129] This comparative example provides a biological packing material. Except for the average particle size of the ferric hydroxide-humic acid complex particles being 10 μm, the biological packing material of this comparative example is identical to that of Example 1. Its preparation method is the same as that of the biological packing material of Example 1, except that a 5% sodium hydroxide solution is used instead of ammonia in step (2).

[0130] The average particle size of the ferric hydroxide-humic acid complex obtained from this comparative biological packing material was 10 μm. The obtained biological packing material was then packed into a biofilter reactor. The packing material has a height of 190 mm and an effective volume of 1.2 L, and is used to treat simulated waste gas containing methanethiol. Methanethiol (nitrogen balance gas) is injected into the mixing tank via a mass flow meter, and air is introduced to dilute it before it is introduced into the reactor. The inlet gas concentration is 30–40 mg / m³. 3The gas residence time is approximately 15 seconds. 1L of a mixed bacterial solution containing sulfur-oxidizing bacteria and highly efficient methanethiol-degrading bacteria (biomass ratio of the two bacteria: 1:1) with a microbial concentration of 1.0 × 10^8 cfu / L is added to the spray solution. This solution is pumped to the top of the reactor by a micro-pump in the circulating water tank for spraying. The spray solution returns to the circulating water tank (20L volume) at the bottom of the reactor. Initially, 10L of tap water is added, and then tap water is periodically replenished to the original level. The removal rate of methanethiol by the reactor is observed and recorded. The removal rate of methanethiol by this biofilter reactor gradually increases. After 10 days of startup, the removal rate remains above 80%, and it can operate stably for more than 200 days.

[0131] Compared to Example 1, Comparative Example 3 uses sodium hydroxide solution instead of ammonia water, resulting in the iron hydroxide-humic acid complex contained in the biological packing material not being nanoparticles. This leads to a significant reduction in the removal rate of methanethiol and a significant shortening of the time for sustainable and stable operation.

[0132] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A biological packing material, characterized in that, The product comprises the following components in parts by weight: 5-10 parts of ferric hydroxide-humic acid complex nanoparticles, 2-10 parts of cyclodextrin, 5 parts of diatomaceous earth, 5-20 parts of biochar, 20-35 parts of ceramsite with through-pores, and 20-30 parts of silicate; it also comprises at least one of calcium hydroxide and calcium salts, wherein the total calcium content of the calcium hydroxide and calcium salts is 0.035-0.090 parts by weight; the average pore diameter of the through-pores in the ceramsite with through-pores is 0.5-5.0 mm, and the porosity of the ceramsite with through-pores is 70-85%.

2. The biological packing material as described in claim 1, characterized in that, The average particle size of the ferric hydroxide-humic acid complex nanoparticles is 5~100 nm, and the mass ratio of ferric hydroxide to humic acid is 1:2~2:

1.

3. The biological packing material as described in claim 1, characterized in that, The cyclodextrin is at least one of α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin.

4. The biological packing material as described in claim 3, characterized in that, The cyclodextrin is β-cyclodextrin.

5. The method for preparing the biological packing material according to any one of claims 1-4, characterized in that, Includes the following steps: (1) Mix aggregate, water and plant fiber evenly, granulate, air dry, heat and fire, cool and anneal to obtain ceramsite with through holes; (2) Dissolve soluble ferric salt in water to obtain ferric salt solution, keep the ferric salt solution at 80-95℃, add ammonia-ethanol-water solution, add humic acid solution while stirring, then continue to keep warm, cool, filter, wash, dry, and obtain black precipitate, which is ferric hydroxide-humic acid complex nanoparticles. (3) Add cyclodextrin to water and stir until completely dissolved. Then add calcium oxide and continue stirring until completely dissolved to obtain sol A. (4) Mix the iron hydroxide-humic acid complex nanoparticles obtained in step (2), diatomaceous earth, biochar and silicate evenly to obtain powder; (5) Disperse the iron hydroxide-humic acid complex nanoparticles obtained in step (2) in water to obtain sol B; (6) The ceramic particles with through holes obtained in step (1) are soaked in the sol B obtained in step (5), air-dried, and then soaked in the sol A obtained in step (3). Then, they are placed in a granulator and rotated at a constant speed. The powder obtained in step (4) is evenly sprinkled into the granulator multiple times. Sol A is sprayed before each powder is sprinkled. The biological filler is obtained by granulation.

6. The method for preparing the biological packing material as described in claim 5, characterized in that, The aggregate comprises the following components in parts by weight: 30-40 parts sludge, 30-40 parts fly ash, 5-10 parts phosphate rock, 5-10 parts clay ore, 1-5 parts magnesium hydroxide, 0.1-1 parts borate, 0.1-2 parts copper hydroxide, 0.1-1 parts molybdate, and 0.1-1 parts cobaltite.

7. The method for preparing the biological packing material as described in claim 5, characterized in that, The volume ratio of the iron salt solution, ammonia-ethanol-water solution, and humic acid solution used in step (2) is 10:1:2-10. The mass concentration of soluble trivalent iron salt in the iron salt solution is 1-5%. The mass ratio of ammonia monohydrate, ethanol, and water in the ammonia-ethanol-water solution is 5-20:30:50-65. The mass concentration of humic acid in the humic acid solution is 1-5%. The addition rate of the ammonia-ethanol-water solution is 5-15 mL / min relative to each 1 L of iron salt solution.

8. The method for preparing the biological packing material as described in claim 5, characterized in that, In step (3), the mass ratio of cyclodextrin, calcium oxide and water used in sol A is 5-10:2-5:10-20, and the total weight of sol A accounts for 5-25% of the total weight of all raw materials used in the preparation of the biological filler.

9. The method for preparing the biological packing material as described in claim 8, characterized in that, In step (3), the total weight of sol A accounts for 20-25% of the total weight of all raw materials used in the preparation of the biological filler.

10. The method for preparing the biological packing material as described in claim 6, characterized in that, At least one of the conditions (a)-(k) must be satisfied: (a) In step (1), the average length of the plant fiber is 15-30 mm and the average diameter is 0.5-5.0 mm; (b) In step (1), the plant fiber includes at least one of straw fiber, bamboo fiber, sugarcane fiber, and coconut shell fiber; (c) In step (1), the volume ratio of the aggregate to the plant fiber is (4-5):1, and the weight of the water used is 5-20% of the total weight of the aggregate and the plant fiber; (d) In step (1), the air-drying operation is carried out in an environment of 15-30℃ and humidity ≤70%, and the air-drying time is 18~30h; (e) In step (1), the specific steps of heating and firing include: heating to 200-300℃ at a heating rate of 5-20℃ / min, holding for 1-2 hours, then heating to 550-600℃ at a heating rate of 5-10℃ / min, holding for 10-30 minutes, then heating to 750-800℃ at a heating rate of 5-40℃ / min, holding for 10-30 minutes, and then heating to 950-1000℃ at a heating rate of 5-40℃ / min, holding for 10-30 minutes; (f) In step (1), the specific steps of the cooling annealing include: cooling to 700±10℃ at a cooling rate of ≤4℃ / min, then cooling to 400±10℃ at a cooling rate of ≤2℃ / min, and then naturally cooling to room temperature; (g) In step (2), after adding the humic acid solution, continue to keep warm for 30~60 minutes; (h) The mass ratio of the iron hydroxide-humic acid complex nanoparticles used in step (4) to the iron hydroxide-humic acid complex nanoparticles used in step (5) is (1-2):1; (i) The mass concentration of the ferric hydroxide-humic acid complex in sol B obtained in step (5) is 1~10%; (j) In step (6), the rotation speed of the uniform rotation is controlled at 25-35 r / min, and the turntable angle is controlled at 30-40°; (k) In step (6), the specific steps for granulating the powder obtained in step (4) by repeatedly and evenly sprinkling it into the granulator are as follows: spray sol A before each sprinkling of powder, and sprinkle the powder into the granulator in 10-20 times with an interval of 2 minutes.

11. The application of the biological packing material as described in any one of claims 1-4 or the biological packing material prepared by the preparation method as described in any one of claims 5-10 in odor treatment.