A biological filler, a preparation method and application thereof

Abstract

The application discloses a biological filler and a preparation method and application thereof, and relates to the field of air pollution control. The biological filler comprises a ceramsite with a through hole, and the through hole of the ceramsite is loaded with iron hydroxide and humic acid. The iron hydroxide and the humic acid are used to effectively promote the oxidation-reduction reaction of a microbial organism, improve the purification efficiency of the microorganism, and form a chelation system with trivalent iron and the like, so that the nutrient substances in the filler are slowly released, and the persistence of the effectiveness of the filler is improved.

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 sustainable and efficient packing material. Furthermore, the development of biological packing materials in China is still in its early stages, and research results are limited by factors such as cost and long-term operational requirements, thus failing to fully solve the aforementioned problems. Summary of the Invention

[0004] Given the deficiencies of existing technologies, the purpose of this invention is to provide a continuously efficient biological packing material, its preparation method, and its application.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a biological filler comprising ceramsite, wherein the ceramsite has through-holes, and the through-holes are loaded with ferric hydroxide and humic acid. The biological filler utilizes the coordination effect between humic acid and ferric hydroxide to fix humic acid within the through-holes of the ceramsite, and the humic acid promotes the growth 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-base interactions, 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). - The presence of reactive oxygen species (ROS) such as · and HO· alleviates the oxidative stress caused by these substances, thereby enhancing the purification efficiency of microorganisms. Compared to biological packing materials without ferric hydroxide and humic acid, or those only loaded with ferric hydroxide without humic acid, this biological packing material not only has a faster start-up speed but also a better removal effect on malodorous gases. When the ceramsite contains nutrients such as minerals, the chelation system formed by humic acid and ferric iron can be utilized to slowly release nutrients from the packing material, improving its long-term effectiveness.

[0006] 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.

[0007] In summary, the biological packing material can promote the rapid initiation of microorganisms, enhance biochemical reactions, slowly release nutrients, and maintain the microenvironment for long-term microbial growth.

[0008] Preferably, the ratio of the mass of the ceramsite to the total mass of the ferric hydroxide and humic acid is 80-90:18-9. Under this specific ratio, the biological filler achieves a more efficient and longer-lasting deodorizing effect.

[0009] Preferably, 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.

[0010] Preferably, at least a portion of the surface of the ceramsite is provided with a gel film, and microorganisms are distributed in the gel film. By providing a gel film containing microorganisms on at least a portion of the surface of the ceramsite, microorganisms can quickly attach to the film, thereby increasing the start-up rate.

[0011] Preferably, the ceramsite gel membrane satisfies at least one of the following conditions:

[0012] (I) The thickness of the gel membrane is 5–20 μm;

[0013] (II) The gel membrane is a biodegradable gel membrane, such as being composed of or mainly composed of at least one of calcium alginate and polyethylene glycol;

[0014] (III) The content of microorganisms in the gel membrane is 1.0×10^6~5.0×10^7 cfu / g;

[0015] (IV) The microorganisms include deodorizing microorganisms, which include at least one of sulfur-oxidizing bacteria, ammonia-oxidizing bacteria, and VOCs-degrading bacteria.

[0016] Excessive gel membrane thickness can lead to insufficient rigidity of the packing material, making it prone to compaction; insufficient gel membrane thickness can result in difficulty in film formation and low microbial content in the packing material, which is not conducive to rapid microbial biofilm formation. When the gel membrane thickness is within the above range, it has little impact on the mechanical properties of the packing material, while facilitating film formation and maintaining a certain microbial content, which is conducive to rapid biofilm formation and achieving the goal of rapid start-up.

[0017] The gel membrane can be either non-biodegradable or biodegradable. A biodegradable gel membrane is more environmentally friendly. As an example, the gel membrane is composed of, or primarily composed of, at least one of, calcium alginate and polyethylene glycol, but the choice of gel membrane is not limited to these.

[0018] If the microbial content in the gel membrane is too high, it will be difficult for the biogel to form a film and the production cost will be too high; if the microbial content in the gel membrane is too low, the microbial content in the packing material will be insufficient, which will not be conducive to the rapid attachment of microorganisms to the membrane; when the microbial content in the gel membrane is within the above range, the biogel is easy to form a film and the microbial content in the packing material is sufficient to enable the microorganisms to attach to the membrane quickly, so as to achieve the purpose of rapid start-up of the device.

[0019] The microorganisms in the gel membrane may include at least one of sulfur-oxidizing bacteria, ammonia-oxidizing bacteria, and VOCs-degrading bacteria, but are not limited to this.

[0020] Preferably, the ceramsite satisfies at least one of the following conditions:

[0021] (A) The average diameter of the through hole is 0.5–5.0 mm;

[0022] (B) The porosity of the ceramsite is 70-85%.

[0023] 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.

[0024] 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.

[0025] In some embodiments, the particle size of the ceramsite is 10–25 mm.

[0026] In some embodiments, the expanded clay aggregates also contain residual plant fibers, the plant fiber content being less than 2% of the filler mass.

[0027] Secondly, the present invention provides a method for preparing the above-mentioned biological packing material, comprising the following steps:

[0028] (1) Mix aggregate, water and plant fiber evenly to prepare rough blanks, granulate, air dry, heat and fire, cool and anneal to obtain ceramsite with through holes.

[0029] (2) Dissolve soluble ferric salt in water to obtain ferric salt solution, then soak the ceramsite with through holes in the ferric salt solution, filter out the ceramsite, air dry, and obtain ceramsite with ferric salt loaded in the through holes.

[0030] (3) Soak the ceramsite loaded with iron salt in the through holes in an alkaline solution, filter, and wash to obtain ceramsite loaded with iron hydroxide in the through holes.

[0031] (4) The ceramic particles loaded with ferric hydroxide in the through holes are soaked in humic acid solution, filtered, and air-dried to obtain ceramic particles loaded with ferric hydroxide and humic acid complex in the through holes.

[0032] (5) Prepare sodium alginate into sodium alginate solution, add microorganisms, mix evenly to obtain a mixture of sodium alginate and microorganisms, then soak the ceramic particles loaded with iron hydroxide and humic acid complex in the through holes in the mixture of sodium alginate and microorganisms, then filter, soak in calcium chloride solution for reaction, and then filter out to obtain biological packing.

[0033] 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.

[0034] The preparation method of the bio-filler involves loading a complex of ferric hydroxide and humic acid using a "precursor introduction-in-pore nucleation-coordination fixation" approach. First, a ferric ion precursor is introduced into the aggregate pores, where it precipitates to form an ferric hydroxide nucleus. Finally, humic acid is fixed within the aggregate through coordination. Under the action of humic acid, Fe exhibits stronger catalytic activity, effectively promoting the redox reactions of microorganisms. Simultaneously, the humic acid-iron catalytic system can also absorb O2 generated during the degradation of H2S and VOCs (volatile organic compounds). - It can eliminate reactive oxygen species (ROS) such as · and HO·, alleviate the oxidative stress they cause, and improve the purification efficiency of microorganisms.

[0035] The preparation method of the biological packing material combines seaweed polysaccharides with excellent water retention capacity with pre-loaded microorganisms, enabling the microorganisms to quickly attach to the biofilm and achieve rapid start-up; and utilizes the chelation system formed by seaweed polysaccharides and humic acid to slowly release nutrients in the packing material, thereby improving the long-term effectiveness of the packing material.

[0036] The biological packing material prepared by the method described above can promote the rapid initiation of microorganisms, enhance biochemical reactions, slowly release nutrients, and maintain the microenvironment for long-term growth of microorganisms.

[0037] 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.

[0038] The ceramsite uses sludge, fly ash, and other materials as aggregates, resulting in low cost and realizing the resource utilization of solid waste. Simultaneously, the added phosphate rock, magnesium hydroxide, borates, copper hydroxide, molybdates, cobaltite, and other raw materials can form corresponding slightly soluble salts, sparingly soluble salts, or oxides during aggregate calcination. During use, these minerals such as P, Mg, B, Cu, Mo, and Co are slowly released through water solubility, acid-base reactions, and coordination, providing long-term and effective inorganic nutrients for microorganisms. Furthermore, the ceramsite provides a rigid framework, maintaining high mechanical strength even after nutrient release, thus preventing problems such as flow interruption and localized anaerobic conditions caused by the collapse of organic or mixed fillers.

[0039] 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.

[0040] 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.

[0041] In some embodiments, the clay mineral is selected from at least one of montmorillonite, kaolinite, vermiculite, etc., and its main component is aluminosilicate.

[0042] Magnesium hydroxide, when calcined, forms magnesium oxide and magnesium salts, enabling the biofiller to release magnesium in a slow-release manner.

[0043] 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.

[0044] Copper hydroxide enables the biological filler to release copper slowly.

[0045] 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.

[0046] Cobaltite enables biofillers to release cobalt in a slow-release manner.

[0047] Preferably, the preparation method satisfies at least one of conditions (a)-(l):

[0048] (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;

[0049] (b) In step (1), the plant fiber includes at least one of straw fiber, bamboo fiber, sugarcane fiber, and coconut shell fiber;

[0050] (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.

[0051] (d) The air drying in steps (1), (3) and (4) is carried out in an environment of 15-30℃ and ≤70% humidity. The air drying time in step (1) is 18-26h, the air drying time in step (3) is 10-14h, and the air drying time in step (4) is 10-14h.

[0052] (e) In step (1), the specific steps of heating and firing include: heating to 200-300°C at a heating rate of 5-20°C / min, holding for 1-2 hours, then heating to 550-600°C at a heating rate of 5-10°C / min, holding for 10-30 minutes, then heating to 750-800°C at a heating rate of 5-40°C / min, holding for 10-30 minutes, and then heating to 950-1000°C at a heating rate of 5-40°C / min, holding for 10-30 minutes.

[0053] (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.

[0054] (g) In step (2), the mass concentration of soluble trivalent iron salt in the iron salt solution is 3-10%, the volume of the iron salt solution is 2-5 times the volume of the ceramsite with through holes, and the soaking time is 6-24h.

[0055] (h) In step (3), the mass concentration of alkali in the alkaline solution is 2-5%, the volume of the alkaline solution is 2-5 times the volume of the ceramic particles with through holes, and the soaking time is 3-6 hours.

[0056] (i) In step (3), the soluble ferric salt includes at least one of ferric chloride, ferric bromide, ferric nitrate, and ferric sulfate, and the alkali in the alkaline solution includes at least one of sodium hydroxide and potassium hydroxide;

[0057] (j) In step (4), the mass concentration of humic acid in the humic acid solution is 1-5%, the volume of the humic acid solution is 2-5 times the volume of the ceramic particles with through holes, and the soaking time is 10-14h.

[0058] (k) In step (5), the mass concentration of sodium alginate in the mixture of sodium alginate and microorganisms is 1-2%, the microbial content is 1.0×10^6-1.0×10^8 cfu / L, the ceramsite loaded with iron hydroxide and humic acid complex in the through holes is soaked in the mixture of sodium alginate and microorganisms for 3-5 hours, the mass concentration of calcium chloride in the calcium chloride solution is 1.0-1.2%, and the reaction time is 1-2 hours;

[0059] (l) In step (5), the mass ratio of polyethylene glycol to chitosan is (1-2):8, the mass fraction of acetic acid in the acetic acid solution is 1-2%, the ratio of the total mass of polyethylene glycol and chitosan to the mass of the acetic acid solution is (0.5-3):100, the mass fraction of sodium hydroxide in the sodium hydroxide solution is 0.4-0.6%, and the ceramsite loaded with iron hydroxide and humic acid complex in the through holes is soaked in the polyethylene glycol-chitosan-microorganism mixture for 3-5 hours.

[0060] In some embodiments, in step (5), the drying before spraying sodium hydroxide solution onto the surface of the obtained filler is vacuum drying, which is carried out at 15-25°C and with a vacuum degree of 0.1-60 kPa.

[0061] In some embodiments, in step (5), the air drying after spraying sodium hydroxide solution onto the surface of the obtained filler is carried out at 15–25°C.

[0062] 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.

[0063] 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.

[0064] 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 to 10 batches, with each batch containing the same proportion of aggregates, water, and plant fibers. The mixing speed is controlled at 10 to 20 r / min, and each batch is mixed for 8 to 20 minutes.

[0065] In some embodiments, 5-30% by weight of soluble ferric salts are added to the remaining ferric chloride solution, 5-30% by weight of alkali is added to the remaining alkaline solution, and 2-20% by weight of humic acid is added to the remaining humic acid solution for the preparation of the next batch of filler.

[0066] Thirdly, the present invention also provides the application of the biological packing material or the biological packing material prepared by the preparation method in waste gas treatment.

[0067] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0068] (1) The biological packing material of the present invention utilizes ferric hydroxide and humic acid to effectively promote the redox reaction of microorganisms and enhance the purification efficiency of microorganisms; when the ceramsite used contains minerals and other nutrients, it can also utilize the chelation system formed by humic acid and ferric iron to slowly release the nutrients in the packing material and enhance the long-term effectiveness of the packing material.

[0069] (2) The biological packing material of the present invention can also utilize gel in combination with pre-loaded microorganisms to enable microorganisms to quickly attach to the membrane and achieve the purpose of rapid start-up.

[0070] (3) The biological packing material of the present invention can also use 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. It 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. Attached Figure Description

[0071] Figure 1 The images show the removal effect of the biological packing material on methanethiol in Examples 1, 10 and Comparative Example 1. Detailed Implementation

[0072] 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 commonly used reagents and instruments.

[0073] Example 1

[0074] This embodiment provides a biological packing material, including ceramsite, which has through-pores loaded with ferric hydroxide and humic acid. At least a portion of the surface of the ceramsite is provided with a gel membrane containing microorganisms. The mass ratio of ceramsite, ferric hydroxide and humic acid, to gel membrane is ceramsite:ferric hydroxide and humic acid:gel membrane = 85:18:2; the mass ratio of ferric hydroxide to humic acid is 2:3; the average pore size of the through-pores is 3.0 mm; the particle size of the ceramsite is 15 mm, and the porosity is 75%; the gel membrane is composed of calcium alginate and has a thickness of 15 μm; the microbial content in the gel membrane is 5.0 × 10^7 cfu / g; the microorganisms are sulfur-oxidizing bacteria and highly efficient methanethiol-degrading bacteria, with a biomass ratio of 1:1.

[0075] The preparation method of the biological packing material in this embodiment includes the following steps:

[0076] (1) Mix aggregate, water, and plant fiber evenly to prepare a rough blank, 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 3.0mm. The aggregate consisted of the following components by weight: 35 parts of plate and frame sludge (moisture content of 65%, containing 20wt% calcium hydroxide or calcium chloride), 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.

[0077] (2) Dissolve ferric chloride in water to obtain a ferric chloride solution with a mass fraction of 5%. Then soak the ceramic particles with through holes obtained in step (1) in the ferric chloride solution (the volume of the ferric chloride solution is 4 times the volume of the ceramic particles with through holes) for 12 hours. Then filter out the ceramic particles and air dry them for 12 hours at 25°C and 60% humidity to obtain ceramic particles with iron salts loaded in the through holes.

[0078] (3) Soak the ceramsite loaded with iron salt in the pores obtained in step (2) in a 3% sodium hydroxide solution for 4 hours (the volume of the alkaline solution is 4 times the volume of the ceramsite), filter, and obtain ceramsite loaded with iron hydroxide in the through pores.

[0079] (4) Soak the ceramic particles with iron hydroxide loaded in the through holes obtained in step (3) in a humic acid solution with a mass fraction of 2% (the volume of the humic acid solution is 4 times the volume of the ceramic particles), filter, and air dry for 12 hours at 25°C and 60% humidity to obtain ceramic particles with iron hydroxide and humic acid complex loaded in the through holes.

[0080] (5) Prepare a sodium alginate solution with a mass fraction of 3%, add an equal volume of a mixed bacterial solution of sulfur-oxidizing bacteria and methanethiol-degrading bacteria with a microbial content of 1.0×10^8 cfu / L, mix evenly to obtain a mixed solution of 1.5% sodium alginate and microbial content of 5.0×10^7 cfu / L, then soak the ceramic particles with iron hydroxide and humic acid complex loaded in the through holes obtained in step (4) in the mixed solution of sodium alginate and microorganisms for 4 hours, then filter, soak in a 1.1% calcium chloride solution for 1 hour, and then filter out to obtain biological packing material.

[0081] 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. The spray solution is pumped to the top of the reactor by a miniature water pump in the circulating water tank. The spray solution then 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. This biological filter reactor was started up in 5 days, maintaining a removal rate of over 95%, and can operate stably for more than 230 days.

[0082] Example 2

[0083] This embodiment provides a biological packing material, including ceramsite, which has through-pores loaded with ferric hydroxide and humic acid. At least a portion of the surface of the ceramsite is provided with a gel membrane containing microorganisms. The mass ratio of ceramsite, ferric hydroxide and humic acid, to gel membrane is ceramsite:ferric hydroxide and humic acid:gel membrane = 90:9:1; the mass ratio of ferric hydroxide to humic acid is 2:3; the average pore size of the through-pores is 0.5 mm; the particle size of the ceramsite is 10 mm, and the porosity is 85%; the gel membrane is composed of calcium alginate and has a thickness of 5 μm; the microbial content in the gel membrane is 5.0 × 10^7 cfu / g; the microorganisms are sulfur-oxidizing bacteria and highly efficient methanethiol-degrading bacteria, with a biomass ratio of 1:1.

[0084] The preparation method of the biological packing material in this embodiment includes the following steps:

[0085] (1) Mix aggregate, water, and plant fiber evenly to prepare a rough blank, granulate to form 10mm 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 700℃ at a cooling rate of 2℃ / 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 15mm and an average fiber diameter of 0.5mm. 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, 3 parts of magnesium hydroxide, 1 part of borate, 2 parts of copper hydroxide powder, 1 part of molybdate, and 1 part of cobaltite powder.

[0086] (2) Dissolve ferric chloride in water to obtain a ferric chloride solution with a mass concentration of 5%. Then soak the ceramic particles with through holes obtained in step (1) in the ferric chloride solution (the volume of the ferric chloride solution is twice the volume of the ceramic particles with through holes) for 12 hours. Then filter out the ceramic particles and air dry them at 15°C and 70% humidity for 12 hours to obtain ceramic particles with iron salts loaded in the through holes.

[0087] (3) Soak the ceramsite loaded with iron salt in the pores obtained in step (2) in a 3% sodium hydroxide solution for 4 hours (the volume of the alkaline solution is twice the volume of the ceramsite), filter, and obtain ceramsite loaded with iron hydroxide in the through pores.

[0088] (4) Soak the ceramic particles with iron hydroxide loaded in the through holes obtained in step (3) in a humic acid solution with a mass fraction of 2% (the volume of the humic acid solution is twice the volume of the ceramic particles), filter, and air dry for 12 hours at 15°C and 70% humidity to obtain ceramic particles with iron hydroxide and humic acid complex loaded in the through holes.

[0089] (5) Prepare a sodium alginate solution with a mass fraction of 2%, add an equal volume of a mixed bacterial solution of sulfur-oxidizing bacteria and methanethiol-degrading bacteria with a microbial content of 1.0×10^8 cfu / L, mix evenly to obtain a mixed solution of 1% sodium alginate and microbial content of 5.0×10^7 cfu / L, then soak the ceramic particles with iron hydroxide and humic acid complex loaded in the through holes obtained in step (4) in the mixed solution of sodium alginate and microorganisms for 4 hours, then filter, soak in a 1.1% calcium chloride solution for 1 hour, and then filter out to obtain biological packing material.

[0090] 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. The spray solution is pumped to the top of the reactor by a miniature water pump in the circulating water tank. 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. This biological filter reactor was started up in 7 days, maintaining a removal rate of over 95%, and can operate stably for 200 days.

[0091] Example 3

[0092] This embodiment provides a biological packing material, including ceramsite, which has through-pores loaded with ferric hydroxide and humic acid. At least a portion of the surface of the ceramsite is provided with a gel membrane containing microorganisms. The mass ratio of ceramsite, ferric hydroxide and humic acid, and gel membrane is ceramsite:ferric hydroxide and humic acid:gel membrane = 80:18:2; the mass ratio of ferric hydroxide and humic acid is 2:3; the average pore size of the through-pores is 5.0 mm; the particle size of the ceramsite is 15 mm, and the porosity is 70%; the gel membrane is calcium alginate with a thickness of 20 μm; the microbial content in the gel membrane is 5.0 × 10^7 cfu / g; the microorganisms are sulfur-oxidizing bacteria and highly efficient methanethiol-degrading bacteria, with a biomass ratio of 1:1.

[0093] The preparation method of the biological packing material in this embodiment includes the following steps:

[0094] (1) Mix aggregate, water, and plant fiber evenly to prepare a rough blank, 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, and then cool to 1℃ / min. The temperature is raised to 400℃ 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 5% of the total weight of aggregate and plant fiber. The plant fiber is straw fiber with an average fiber length of 20 mm and an average fiber diameter of 5.0 mm. The aggregate includes the following components by weight: 35 parts of plate and frame sludge (sludge with a water content of 75%, made from activated sludge with a water content of 80%, and lime added at 7 wt% of the total sludge mass), 35 parts of fly ash, 10 parts of phosphate rock powder, 10 parts of clay ore powder, 3 parts of magnesium hydroxide, 1 part of borate, 2 parts of copper hydroxide powder, 1 part of molybdate, and 1 part of cobaltite powder.

[0095] (2) Dissolve ferric chloride in water to obtain a ferric chloride solution with a mass fraction of 5%. Then soak the ceramic particles with through holes obtained in step (1) in the ferric chloride solution (the volume of the ferric chloride solution is 5 times the volume of the ceramic particles with through holes) for 6 hours. Then filter out the ceramic particles and air dry them for 12 hours at 30°C and 60% humidity to obtain ceramic particles with iron salts loaded in the through holes.

[0096] (3) Soak the ceramsite loaded with iron salt in the pores obtained in step (2) in a 3% sodium hydroxide solution for 3 hours (the volume of the alkaline solution is 5 times the volume of the ceramsite), filter, and obtain ceramsite loaded with iron hydroxide in the through pores.

[0097] (4) Soak the ceramic particles with iron hydroxide loaded in the through holes obtained in step (3) in a humic acid solution with a mass fraction of 2% (the volume of the humic acid solution is 5 times the volume of the ceramic particles), filter, and air dry for 12 hours at 30°C and 60% humidity to obtain ceramic particles with iron hydroxide and humic acid complex loaded in the through holes.

[0098] (5) Prepare a sodium alginate solution with a mass fraction of 4%, add an equal volume of a mixed bacterial solution of sulfur-oxidizing bacteria and methanethiol-degrading bacteria with a microbial content of 1.0×10^8 cfu / L, mix evenly to obtain a mixed solution of 2% sodium alginate and microbial content of 5.0×10^7 cfu / L, then soak the ceramic particles with iron hydroxide and humic acid complex loaded in the through holes obtained in step (4) in the mixed solution of sodium alginate and microorganisms for 4 hours, then filter, soak in a 1.1% calcium chloride solution for 1 hour, and then filter out to obtain biological packing material.

[0099] 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. The spray solution is pumped to the top of the reactor by a micro-pump in the circulating water tank, and 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 subsequently, tap water is periodically replenished to the original level. The removal rate of methanethiol by the reactor is observed and recorded. This biological filter reactor completes startup in 5 days, maintains a removal rate of over 95%, and can operate stably for 200 days.

[0100] Example 4

[0101] This embodiment provides a biological packing material, including ceramsite, which has through-holes loaded with ferric hydroxide and humic acid. A gel membrane is provided on the surface of the through-holes and their outer surfaces, and microorganisms are distributed within the gel membrane. The mass ratio of ceramsite, ferric hydroxide and humic acid, to the gel membrane is ceramsite:ferric hydroxide and humic acid:gel membrane = 85:18:2; the mass ratio of ferric hydroxide to humic acid is 2:3; the average pore size of the through-holes is 3.0 mm; the particle size of the ceramsite is 25 mm, and the porosity is 70%; the gel membrane is composed of calcium alginate and has a thickness of 15 μm; the microbial content in the gel membrane is 5.0 × 10^7 cfu / g; the microorganisms are sulfur-oxidizing bacteria and highly efficient methanethiol-degrading bacteria, with a biomass ratio of 1:1.

[0102] The preparation method of the biological packing material in this embodiment includes the following steps:

[0103] (1) Mix aggregate, water, and plant fiber evenly to prepare a rough blank, granulate to form spherical mud particles of 25 mm, sieve to remove unqualified mud particles smaller than 5 mm, air dry at 25℃ and 60% humidity for 12 h, heat to 250℃ at a heating rate of 12℃ / min, hold for 1 h, then heat to 580℃ at a heating rate of 7℃ / min, hold for 20 min, then heat to 780℃ at a heating rate of 20℃ / min, hold for 20 min, then heat to 980℃ at a heating rate of 20℃ / min, hold for 20 min, then cool to 700℃ at a cooling rate of 3℃ / min, and then cool to 400℃ at a cooling rate of 1.5℃ / min. The mixture is heated to 00℃ 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 3.0mm. The aggregate consists of the following components by weight: 40 parts of sludge (sludge with a water content of 60%, made from activated sludge with a water content of 80%, and lime added at 30wt% of the total sludge mass), 30 parts of fly ash, 5 parts of phosphate rock powder, 5 parts of clay ore powder, 1 part of magnesium hydroxide, 0.1 parts of borax, 0.1 parts of copper hydroxide powder, 0.1 parts of molybdenum-calcium ore, and 0.1 parts of cobaltite powder.

[0104] (2) Dissolve ferric chloride in water to obtain a ferric chloride solution with a mass fraction of 5%. Then soak the ceramic particles with through holes obtained in step (1) in the ferric chloride solution (the volume of the ferric chloride solution is 5 times the volume of the ceramic particles with through holes) for 24 hours. Then filter out the ceramic particles and air dry them for 12 hours at 25°C and 60% humidity to obtain ceramic particles with iron salts loaded in the through holes.

[0105] (3) Soak the ceramsite loaded with iron salt in the pores obtained in step (2) in a 3% sodium hydroxide solution for 6 hours (the volume of the alkaline solution is 5 times the volume of the ceramsite), filter, and obtain ceramsite loaded with iron hydroxide in the through pores.

[0106] (4) Soak the ceramic particles with iron hydroxide loaded in the through holes obtained in step (3) in a humic acid solution with a mass fraction of 2% (the volume of the humic acid solution is 5 times the volume of the ceramic particles), filter, and air dry for 12 hours at 25°C and 60% humidity to obtain ceramic particles with iron hydroxide and humic acid complex loaded in the through holes.

[0107] (5) Prepare a sodium alginate solution with a mass fraction of 3%, add an equal volume of a mixed bacterial solution of sulfur-oxidizing bacteria and methanethiol-degrading bacteria with a microbial content of 1.0×10^8 cfu / L, mix evenly to obtain a mixed solution of 1.5% sodium alginate and microbial content of 5.0×10^7 cfu / L, then soak the ceramic particles with iron hydroxide and humic acid complex loaded in the through holes obtained in step (4) in the mixed solution of sodium alginate and microorganisms for 4 hours, then filter, soak in a 1.1% calcium chloride solution for 1 hour, and then filter out to obtain biological packing material.

[0108] 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. The spray solution is pumped to the top of the reactor by a miniature water pump in the circulating water tank. 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. This biological filter reactor was started up in 5 days, maintaining a removal rate of over 95%, and can operate stably for 150 days.

[0109] Example 5

[0110] This embodiment provides a biological packing material. Except that the microorganisms in the gel membrane of this embodiment are ammonia-oxidizing bacteria and trimethylamine-efficient degrading bacteria, and the microbial content is 1.0 × 10^7 cfu / g, everything else in this embodiment is the same as in Example 1. The preparation method of the biological packing material in this embodiment is the same as in Example 1, except that in step (5), sodium alginate is prepared into a 3% (w / w) sodium alginate solution, and an equal volume of ammonia-oxidizing bacteria and trimethylamine mixed bacterial solution with a microbial content of 2.0 × 10^7 cfu / L (biomass ratio of 1:1) is added and mixed evenly to obtain a mixture of 1.5 wt% sodium alginate and a microbial content of 5.0 × 10^7 cfu / L.

[0111] 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 trimethylamine. Trimethylamine (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 10–20 mg / m³. 3The gas residence time is approximately 15 seconds. The spray solution is pumped to the top of the reactor by a miniature water pump in the circulating water tank. 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. This biological filter reactor was started up in 10 days, maintaining a removal rate above 95%, and can operate stably for more than 230 days.

[0112] Example 6

[0113] This embodiment provides a biological packing material. Except for the mass ratio of ferric hydroxide to humic acid in the complex of ferric hydroxide and humic acid being 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 the mass fraction of ferric chloride solution in step (2) is 3%, the ferric chloride solution is 10 times the mass fraction of the resulting porous ceramic particles, and the mass fraction of humic acid solution in step (4) is 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. The spray solution is pumped to the top of the reactor by a miniature water pump in the circulating water tank. The spray solution then 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. This biofilter reactor was started up in 5 days, maintaining a removal rate of over 95%, and can operate stably for 180 days.

[0115] Example 7

[0116] This embodiment provides a biological packing material. Except for the ferric hydroxide and humic acid complex, where the mass ratio of ferric hydroxide to humic acid is 2:1, the preparation method of this biological packing material is the same as in Example 1. The preparation method is the same as in Example 1, except that in step (2) the ferric chloride solution has a mass fraction of 10% and is 5 times the amount of the resulting porous ceramic particles, and in step (4) the humic acid solution has a mass fraction of 2%.

[0117] 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. The spray solution is pumped to the top of the reactor by a miniature water pump in the circulating water tank. The spray solution then 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. This biofilter reactor was started up in 5 days, maintaining a removal rate above 95%, and can operate stably for 170 days.

[0118] Example 8

[0119] This embodiment provides a biological packing material. Except for the mass ratio of ferric hydroxide to humic acid in the ferric hydroxide-humic acid complex being 1:3, 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 the mass fraction of ferric chloride solution in step (2) is 1%, the ferric chloride solution is 10 times the mass fraction of the resulting porous ceramic particles, and the mass fraction of humic acid solution in step (4) is 5%.

[0120] 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. The spray solution is pumped to the top of the reactor by a miniature water pump in the circulating water tank. The spray solution then 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. This biological filter reactor was started up in 5 days, maintaining a removal rate above 95%, and can operate stably for 160 days.

[0121] Example 9

[0122] This embodiment provides a biological packing material. Except for the ferric hydroxide and humic acid complex, where the mass ratio of ferric hydroxide to humic acid is 3:1, the preparation method of this biological packing material is the same as in Example 1. The preparation method is the same as in Example 1, except that in step (2) the ferric chloride solution has a mass fraction of 10%, the ferric chloride solution is 20 times the mass of the resulting porous ceramic particles, and in step (4) the humic acid solution has a mass fraction of 1%.

[0123] 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. The spray solution is pumped to the top of the reactor by a miniature water pump in the circulating water tank. The spray solution then 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. This biological filter reactor was started up in 5 days, maintaining a removal rate above 95%, and can operate stably for 160 days.

[0124] Example 10

[0125] This embodiment provides a biological packing material. Except for the absence of a gel membrane and microorganisms, the biological packing material of this embodiment 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 step (5) is omitted.

[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 (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. This biofilter reactor completes startup in 12 days, maintains a removal rate of approximately 90%, and can operate stably for 200 days.

[0127] Comparative Example 1

[0128] This comparative example provides a biological packing material. Except for the absence of humic acid, gel membrane, and microorganisms, the biological packing material of this comparative example is identical to that of Example 1. Its preparation method is identical to that of the biological packing material of Example 1, except that steps (4) and (5) are omitted.

[0129] 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 was approximately 15 seconds. 1 L 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 × 10⁸ CFU / L was added to the spray solution. This solution was pumped to the top of the reactor by a micro-pump in the circulating water tank for spraying. The spray solution returned to the circulating water tank (20 L volume) at the bottom of the reactor. Initially, 10 L of tap water was added, and subsequently, tap water was periodically replenished to the original level. The removal rate of methanethiol by the reactor was observed and recorded. This biofilter reactor was started up in 15 days, maintaining a removal rate of 70–85%, and could operate stably for 150 days. Both the removal rate and the maintenance time were significantly lower than in Example 1.

[0130] Comparative Example 2

[0131] This comparative example provides a biological packing material. Except for the ratio of the mass of the ceramsite to the total mass of the ferric hydroxide and humic acid being 95:5, the biological packing material of this comparative example is identical to that of Example 1. Its preparation method is identical to that of the biological packing material of Example 1, except that the ferric chloride solution has a mass fraction concentration of 0.5%, the ferric chloride solution is 20 times the mass fraction of the obtained ceramsite with through-holes, and the humic acid solution has a mass fraction concentration of 0.5% in step (4).

[0132] 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 was approximately 15 seconds. The spray solution was pumped to the top of the reactor by a micro-pump in the circulating water tank for spraying. The spray solution returned to the circulating water tank at the bottom of the reactor. The circulating water tank had a volume of 20L. Initially, 10L of tap water was added, and then tap water was periodically replenished to the original level. The removal rate of methanethiol by the reactor was observed and recorded. This biofilter reactor was started up in 10 days, maintaining a removal rate of 75-85%, and could operate stably for 120 days. Both the removal rate and the maintenance time were significantly lower than in Example 1.

[0133] Comparative Example 3

[0134] This comparative example provides a biological packing material. Except for the absence of through-pores in the ceramsite, 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 plant fibers are not added during the preparation of the rough blank.

[0135] 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 was approximately 15 seconds. The spray solution was pumped to the top of the reactor by a micro-pump in the circulating water tank for spraying. The spray solution returned to the circulating water tank at the bottom of the reactor. The circulating water tank had a volume of 20L. Initially, 10L of tap water was added, and then tap water was periodically replenished to the original level. The removal rate of methanethiol by the reactor was observed and recorded. This biofilter reactor was started up in 10 days, maintaining a removal rate of 75-85%, and could operate stably for 60 days. Both the removal rate and the maintenance time were significantly lower than in Example 1.

[0136] 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 includes expanded clay aggregate, which has through holes and is loaded with ferric hydroxide and humic acid. The mass ratio of the expanded clay aggregate to the total mass of the ferric hydroxide and humic acid is 80-90:18-9. The ceramsite meets at least one of the following conditions: (A) The average diameter of the through hole is 0.5~5.0 mm; (B) The porosity of the ceramsite is 70-85%.

2. The biological packing material as described in claim 1, characterized in that, The mass ratio of the ferric hydroxide to the humic acid is 1:2 to 2:

1.

3. The biological packing material according to any one of claims 1 to 2, characterized in that, At least a portion of the surface of the ceramic pellet is provided with a gel film, in which microorganisms are distributed.

4. The biological packing material as described in claim 3, characterized in that, The mass ratio of the ceramic particles to the gel membrane is 80~90:2~1.

5. The biological packing material as described in claim 3, characterized in that, The gel membrane satisfies at least one of the following conditions: (I) The thickness of the gel membrane is 5~20 μm; (II) The gel membrane is a biodegradable gel membrane, composed of or mainly composed of at least one of calcium alginate, polyethylene glycol and chitosan; (III) The content of microorganisms in the gel membrane is 1.0×10^6~5.0×10^7 cfu / g; (IV) The microorganisms include deodorizing microorganisms, which include at least one of sulfur-oxidizing bacteria, ammonia-oxidizing bacteria, and VOCs-degrading bacteria.

6. A method for preparing a biological packing material, characterized in that, Includes the following steps: (1) Mix aggregate, water and plant fiber evenly to prepare rough blanks, 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, then soak the ceramsite with through holes in the ferric salt solution, then filter out the ceramsite, air dry, and obtain ceramsite with ferric salt loaded in the through holes; (3) Soak the ceramsite loaded with iron salt in the through holes in an alkaline solution, filter, and wash to obtain ceramsite loaded with iron hydroxide in the through holes. (4) The ceramic particles loaded with ferric hydroxide in the through holes are soaked in humic acid solution, filtered, and air-dried to obtain ceramic particles loaded with ferric hydroxide and humic acid complex in the through holes. (5) Prepare sodium alginate into sodium alginate solution, add microorganisms, mix evenly to obtain a mixture of sodium alginate and microorganisms, then soak the ceramic particles loaded with iron hydroxide and humic acid complex in the through holes in the mixture of sodium alginate and microorganisms, then filter, soak in calcium chloride solution for reaction, then filter out to obtain biological filler, or dissolve polyethylene glycol and chitosan in acetic acid solution, add microorganisms, mix evenly to obtain a mixture of polyethylene glycol-chitosan-microorganisms, then soak the ceramic particles loaded with iron hydroxide and humic acid complex in the through holes in the mixture of polyethylene glycol-chitosan-microorganisms, filter, dry, then spray sodium hydroxide solution on the surface of the obtained filler, air dry to obtain biological filler.

7. The method for preparing the biological packing material as described in claim 6, characterized in that, The raw materials for preparing the aggregate include 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.

8. The method for preparing the biological packing material as described in claim 6, characterized in that, At least one of conditions (a)-(l) 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), during the preparation of the rough blank, the volume ratio of aggregate to plant fiber is (4~5):1, and the weight of water used is 5~20% of the total weight of the aggregate and the plant fiber; (d) The air drying in steps (1), (2) and (4) is carried out in an environment of 15~30℃ and humidity ≤70%, wherein the air drying time in step (1) is 18~26h, the air drying time in step (2) is 10~14h, and the air drying time in step (4) is 10~14h. (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), the mass concentration of soluble trivalent iron salt in the iron salt solution is 3~10%, the volume of the iron salt solution is 2~5 times the volume of the ceramic particles with through holes, and the soaking time is 6~24 h; (h) In step (3), the mass concentration of alkali in the alkaline solution is 2-5%, the volume of the alkaline solution is 2-5 times the volume of the ceramic particles with through holes, and the soaking time is 3-6 h; (i) In step (3), the soluble ferric salt includes at least one of ferric chloride, ferric bromide, ferric nitrate, and ferric sulfate, and the alkali in the alkaline solution includes at least one of sodium hydroxide and potassium hydroxide; (j) In step (4), the mass concentration of humic acid in the humic acid solution is 1~5%, the volume of the humic acid solution is 2~5 times the volume of the ceramic particles with through holes, and the soaking time is 10~14 h. (k) In step (5), the mass concentration of sodium alginate in the mixture of sodium alginate and microorganisms is 1~2%, the microbial content is 1.0×10^6~1.0×10^8 cfu / L, the ceramsite loaded with iron hydroxide and humic acid complex in the through holes is soaked in the mixture of sodium alginate and microorganisms for 3~5 h, the mass concentration of calcium chloride in the calcium chloride solution is 1.0~1.2%, and the reaction time is 1~2 h; (l) In step (5), the mass ratio of polyethylene glycol to chitosan is (1~2):8, the mass fraction of acetic acid in the acetic acid solution is 1~2%, the ratio of the total mass of polyethylene glycol and chitosan to the mass of the acetic acid solution is (0.5~3):100, the mass fraction of sodium hydroxide in the sodium hydroxide solution is 0.4~0.6%, and the ceramsite loaded with iron hydroxide and humic acid complex in the through holes is soaked in the polyethylene glycol-chitosan-microorganism mixture for 3~5 h.

9. The application of the biological packing material as described in any one of claims 1 to 5 or the biological packing material prepared by the preparation method as described in any one of claims 6 to 8 in waste gas treatment.

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