Waste gas treatment system, application of waste gas treatment system and treatment method for malodorous gas generated by domestic waste landfill

Abstract

The invention belongs to the technical field of environmental governance, and particularly relates to a waste gas treatment system, application thereof and a treatment method for malodorous gas generated by a household garbage landfill. The waste gas treatment system provided by the invention comprises an alkali washing spray tower, a biological filter bed of which a bottom first gas inlet is communicated with a top outlet of the alkali washing spray tower, a deodorization spray tower of which a bottom gas second inlet is communicated with a top outlet of the biological filter bed, and an emptying pipe communicated with a top outlet of the deodorization spray tower. When the waste gas treatment system is used for treating malodorous gas, the malodorous gas can be subjected to three-step purification treatment of primary gas-liquid mass transfer, microbial degradation and secondary gas-liquid mass transfer, various harmful substances in the waste gas can be efficiently removed, meanwhile, the system is not prone to leakage, continuous treatment can be achieved, and the waste gas treatment efficiency is improved. And the secondary pollution is reduced while the treatment effect is ensured.

Description

Technical Field

[0001] This invention belongs to the field of environmental governance technology, specifically relating to a waste gas treatment system and its application, and a method for treating malodorous gases generated in municipal solid waste landfills. Background Technology

[0002] Municipal solid waste landfills continuously generate foul odors throughout their entire life cycle. These odors primarily originate from gases produced during the decomposition of organic matter in the landfill process, such as hydrogen sulfide, ammonia, methane, and carbon dioxide, as well as other potentially released harmful gases. Simultaneously, the infiltration of large amounts of rainwater into the landfill produces leachate, further exacerbating the odor problem. These foul gases can negatively impact the quality of life for nearby residents; therefore, odor control is a crucial aspect of the entire life cycle management of municipal solid waste landfills.

[0003] Currently, chemical absorption or physical adsorption are the main methods used to treat the odor generated from municipal solid waste landfills. However, these methods have low efficiency in treating odorous gases and there is a risk of odor leakage. Furthermore, the odors generated from municipal solid waste landfills are characterized by high concentrations (H2S 1000~5000 mg / m³). 3 NH3 concentration is 500~2000 mg / m³ 3 It is characterized by its complex composition (containing malodorous substances such as thiols and amines), strong corrosiveness (acidic gases corrode equipment), and high biological toxicity (H2S is highly toxic); gas leaks during the treatment process can cause secondary pollution and other problems. Summary of the Invention

[0004] In view of this, the present invention provides a waste gas treatment system and its application, and a method for treating odorous gases generated in municipal solid waste landfills; the waste gas treatment system provided by the present invention can efficiently treat odorous gases and has the advantages of no secondary pollution (not easy to leak), exhaust gas emission in compliance with standards, and low operating costs.

[0005] To solve the above-mentioned technical problems, the present invention provides a waste gas treatment system, including an alkaline scrubbing spray tower 1, a biological filter bed 2 with a bottom first gas inlet 21 connected to the top outlet 15 of the alkaline scrubbing spray tower, a deodorizing spray tower 3 with a bottom second gas inlet 31 connected to the top outlet 23 of the biological filter bed, and an exhaust pipe 4 connected to the top outlet 35 of the deodorizing spray tower.

[0006] Preferably, the lower part of the alkaline scrubbing tower 1 is provided with an exhaust gas inlet 11, the upper part of the alkaline scrubbing tower 1 is provided with an alkaline spray head, and the upper part of the alkaline spray head is provided with a first demister 12; the alkaline spray head is connected to the lower outlet of the alkaline storage container 13 through a first delivery pump 14; the bottom outlet of the alkaline scrubbing tower 1 is connected to the top inlet of the alkaline storage container 13. The alkaline washing spray tower 1 is equipped with packing material; a level gauge is installed on the lower side of the alkaline washing spray tower 1.

[0007] Preferably, the biofilter bed 2 is provided with a composite filter media layer, a pH meter, a level gauge and a circulation device; the circulation device includes a humidifying nozzle disposed on the upper part of the composite filter media layer, and the humidifying nozzle is connected to the nutrient solution at the bottom of the biofilter bed through a circulation pump 22.

[0008] Preferably, the composite filter media in the composite filter media layer includes an active component and a carrier, wherein the carrier is a hollow polypropylene sphere; The active component comprises the following components in mass percentage: 35-45% expanded clay aggregate; 25-32% volcanic rock; 23-28% pine bark; Activated carbon 4-6%.

[0009] Preferably, the upper part of the deodorizing spray tower 3 is provided with a deodorizing agent nozzle, and the upper part of the deodorizing agent nozzle is provided with a second demister 32; the deodorizing agent nozzle is connected to the lower outlet of the deodorizing agent storage container 33 through a second delivery pump 34; the bottom outlet of the deodorizing spray tower 3 is connected to the top inlet of the deodorizing agent storage container 33. The deodorizing spray tower 3 is equipped with packing material; a level gauge is installed on the lower side of the deodorizing spray tower 3.

[0010] The present invention also provides the application of the exhaust gas treatment system described above in the treatment of malodorous gases generated in municipal solid waste landfills.

[0011] This invention also provides a method for treating malodorous gases generated in municipal solid waste landfills, comprising the following steps: The malodorous gas generated from the municipal solid waste landfill is transported to the alkaline scrubbing spray tower 1 and subjected to alkaline scrubbing by counter-current contact with alkaline solution to obtain primary deodorized gas; The primary deodorized gas is transported to the biofilter 2 for biological deodorization to obtain secondary deodorized gas; the pressure drop of the biofilter during the biological deodorization operation is 500~1000Pa / m. The secondary deodorized gas is transported to the deodorization spray tower 3 and comes into counter-current contact with the deodorizing agent solution for deodorization, resulting in deodorized gas; The deodorized gas is then exhausted through exhaust pipe 4.

[0012] Preferably, the flow rate of the malodorous gas is 1200~1300 m³ / h. 3 / h; The alkaline solution includes a sodium hydroxide solution, and the pH value of the alkaline solution is 11-13; The liquid-to-gas ratio of the alkaline washing is 5~15 L / m³. 3 .

[0013] Preferably, the functional microbial community used in the biological deodorization includes one or more of sulfur bacteria, nitrifying bacteria, denitrifying bacteria, Bacillus, Pseudomonas, and yeast; The flow rate of the primary deodorizing gas is 1200~1300 m³ / h. 3 / h; The relative humidity of the biological deodorization environment is 40-60%, the pH value is 6.5-8.5, and the temperature is 20-30℃.

[0014] Preferably, the deodorant in the deodorant solution includes a plant-based deodorant; The flow rate of the secondary deodorizing gas is 1200~1300 m³ / h. 3 / h, the volume ratio of the secondary deodorizing gas to the mass ratio of the plant-based deodorizing agent is 98~100m³. 3 1kg.

[0015] This invention provides a waste gas treatment system, comprising an alkaline scrubbing spray tower 1, a biofilter bed 2 connected to a bottom first gas inlet 21 and a top outlet 15 of the alkaline scrubbing spray tower, a deodorizing spray tower 3 connected to a bottom second gas inlet 31 and a top outlet 23 of the biofilter bed, and an exhaust pipe 4 connected to a top outlet 35 of the deodorizing spray tower. When treating odorous gases using the waste gas treatment system provided by this invention, it can perform a three-step purification process of "primary gas-liquid mass transfer → microbial degradation → secondary gas-liquid mass transfer," efficiently removing various harmful substances from the waste gas. Furthermore, the system provided by this invention is not prone to leakage, enabling continuous treatment while ensuring treatment effectiveness and reducing secondary pollution. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the waste gas treatment system provided by the present invention; Figure 2 This is a schematic diagram of the odor gas treatment system for a municipal solid waste landfill used in an embodiment of the present invention; Figure 1 and Figure 2 1 is the alkaline scrubbing spray tower, 11 is the exhaust gas inlet, 12 is the first demister, 13 is the alkaline solution storage container, 14 is the first transfer pump, 15 is the top outlet of the alkaline scrubbing spray tower, 2 is the biological filter bed, 21 is the first gas inlet, 22 is the circulation pump, 23 is the top outlet of the biological filter bed, 3 is the deodorizing spray tower, 31 is the second gas inlet, 32 is the second demister, 33 is the deodorizing agent storage container, 34 is the second transfer pump, 35 is the top outlet of the deodorizing spray tower, and 4 is the vent pipe. Detailed Implementation

[0017] The present invention provides a waste gas treatment system, including an alkaline scrubbing spray tower 1, a biological filter bed 2 with a bottom first gas inlet 21 connected to the top outlet 15 of the alkaline scrubbing spray tower, a deodorizing spray tower 3 with a bottom second gas inlet 31 connected to the top outlet 23 of the biological filter bed, and an exhaust pipe 4 connected to the top outlet 35 of the deodorizing spray tower.

[0018] In one specific embodiment of the present invention, the lower part of the alkaline scrubbing tower 1 is provided with a waste gas inlet 11, and the upper part of the alkaline scrubbing tower 1 is provided with an alkaline spray head, and the upper part of the alkaline spray head is provided with a first demister 12; the alkaline spray head is connected to the lower outlet of the alkaline storage container 13 through a first delivery pump 14; the bottom outlet of the alkaline scrubbing tower 1 is connected to the top inlet of the alkaline storage container 13; the alkaline scrubbing tower 1 is provided with packing material, which can be PP packing material, and the specific surface area of ​​the packing material is 500 m². 2 / m 3 The above measures can increase the contact area between the alkaline solution and the waste gas. A level gauge is installed on the side of the lower part of the alkaline scrubbing tower 1. The present invention can control the level of the alkaline solution in the lower part of the alkaline scrubbing tower 1 through a float valve.

[0019] In one specific embodiment of the present invention, the shell material of the alkaline washing spray tower 1 can be SUS304 (austenitic stainless steel), and the thickness of the SUS304 can be 1.5mm; the specifications of the alkaline washing spray tower 1 can be... The first transfer pump 14 has a diameter of 1000×H3500mm; the material of the flow passage of the first transfer pump 14 can be SUS304 or fiber-reinforced polypropylene (FRPP), and the power of the first transfer pump 14 can be 0.74~0.75kW; the present invention can set up a standby pump for the first transfer pump 14 to ensure continuous operation. In the present invention, the alkaline washing spray tower 1 has high strength and corrosion resistance.

[0020] In this invention, the alkaline solution storage container 13 may be equipped with a pH meter, a filter, an automatic water replenishment device, an overflow water seal device, and a sewage outlet, and the sewage outlet may be connected to a gravity sewage pipe.

[0021] In one specific embodiment of the present invention, the dimensions of the biofilter bed can be 4000×2000×1500mm; the outer shell material of the biofilter bed can be SUS304, and the thickness of the SUS304 can be 2.0mm. The material of the flow-through part of the circulation pump can be fiber-reinforced polypropylene (FRPP), and the power of the circulation pump 22 can be 2.2kW.

[0022] In one specific embodiment of the present invention, the biofilter bed is provided with a composite filter media layer, a pH meter, a level gauge and a circulation device; the present invention can control the water level in the biofilter bed by means of a float valve; the circulation device includes a humidifying nozzle disposed on the upper part of the composite filter media layer, and the humidifying nozzle is connected to the water or nutrient solution at the bottom of the biofilter bed through a circulation pump 22.

[0023] In one specific embodiment of the present invention, the biological filter bed 2 may be equipped with baffles, the number of which can be 2 to 5, specifically 2 or 3; the height of the baffles can be 2 / 3 of the height of the biological filter bed; the baffles are alternately fixed to the top surface, bottom surface, and sides of the biological filter bed. The present invention can increase or decrease the number of baffles according to the gas residence time requirements and whether different treatment zones need to be separated; the baffles form S-shaped gas flow channels within the chamber, guiding the airflow and extending the residence time; preventing gas from penetrating the biological filter bed chamber along a straight path with minimal distance. Simultaneously, the baffles can divide the biological filter bed chamber into independent zones with different functions.

[0024] In this invention, the composite filter media in the composite filter media layer may include an active component and a carrier, wherein the carrier may be hollow polypropylene spheres; the diameter of the hollow polypropylene spheres may be 90-110 mm, specifically 100 mm. In this invention, the active component, by mass percentage, may include 35-45% ceramsite, specifically 38%, 40%, or 43%. In this invention, the ceramsite may include small-diameter ceramsite and large-diameter ceramsite; the particle size of the small-diameter ceramsite may be greater than or equal to 4 mm and less than 6 mm; the particle size of the large-diameter ceramsite may be greater than or equal to 6 mm and less than 8 mm; the mass percentage of the small-diameter ceramsite in the total ceramsite may be 58-62%, specifically 60%.

[0025] In this invention, the functions of the ceramsite are as follows: ① Providing physical structure: It has high mechanical strength, serving as the "skeleton" of the filter bed, preventing the composite filter layer from being compacted during long-term use, thereby maintaining high porosity and ensuring uniform gas distribution and low resistance. ② Regulating hydraulic characteristics: The porous structure of the composite filter layer can effectively retain water without easily accumulating it, helping to maintain suitable humidity inside the composite filter layer. ③ Buffering pH value: Ceramsite is fired at high temperatures during the production process and is usually weakly alkaline. When microorganisms degrade sulfur- and nitrogen-containing malodorous substances, leading to environmental acidification, ceramsite can slowly release alkaline substances to neutralize acidic products and stabilize the system pH value, which is crucial for pH-sensitive microorganisms such as nitrifying bacteria. ④ Microbial carrier: The rough surface of the composite filter media provides good attachment points for microorganisms.

[0026] In this invention, the active component, by mass percentage, may include 25-32% volcanic rock, specifically 28% or 30%. In this invention, the average particle size of the volcanic rock may be 6-10 mm, specifically 7 mm or 8 mm. The specific functions of the volcanic rock in this invention are as follows: ① Excellent biofilm substrate: Naturally porous with a large specific surface area, a rough surface, and a positive charge, which is conducive to the adsorption and biofilm formation of negatively charged microbial cells, enabling rapid enrichment of microbial communities. ② Improved air and water permeability: Lightweight and porous, working synergistically with ceramsite to further ensure the air permeability and permeability of the filler layer. ③ Provision of trace elements: Contains trace minerals such as iron, calcium, magnesium, and potassium, which are important components of microbial enzyme cofactors and cell structures, promoting microbial metabolic activity. ④ Assisted pH regulation: Some volcanic rocks are weakly alkaline and can serve as an auxiliary pH buffer material.

[0027] In this invention, the active component, by mass percentage, may include 23-28% pine bark, specifically 24% or 25%. The length of the pine bark may be 25-35 mm, specifically 28 mm, 30 mm, or 32 mm; the thickness may be 3-10 mm, specifically 5 mm or 8 mm. The specific functions of the pine bark in this invention are as follows: ① Providing carbon source and nutrients: Pine bark slowly degrades under the action of microorganisms, continuously releasing nutrients such as organic carbon, nitrogen, and phosphorus, providing a long-term nutrient supply for heterotrophic deodorizing microorganisms (such as bacteria and fungi that degrade VOCs), reducing the need for external nutrient solution addition. ② Excellent water retention and moisture retention capacity: The fiber structure can absorb and retain a large amount of moisture, stabilizing the humidity inside the filter bed like a "sponge," preventing dryness due to airflow, which is a basic condition for the survival and activity of microorganisms. ③ Improves filter media structure: Its loose texture effectively prevents the dense accumulation of inorganic fillers (ceramsite, volcanic rock), keeps pores open, and alleviates filler caking. ④ Unique microbial community: Its surface and interior easily accumulate lignin-degrading bacteria, actinomycetes, and fungi, which have a special effect on degrading complex organic odorous substances (such as sulfides, indole, etc.).

[0028] In this invention, the active component, by mass percentage, may include 4-6% activated carbon, specifically 5%. In this invention, the activated carbon may be bamboo charcoal; the average particle size of the activated carbon may be 4-6 mm, specifically 5 mm. In this invention, the activated carbon functions as follows: ① Strong adsorption and buffering: With a large specific surface area and well-developed microporous structure, it can instantly adsorb high concentrations or shock loads of malodorous gas molecules (such as non-polar benzene compounds and hydrophobic VOCs). This buys time for microbial degradation reactions, preventing the system from being "washed out," and greatly enhancing the stability and shock resistance of the composite filter layer. ② Enrichment of functional microorganisms: Its micropores can serve as "nanoscale housing" for microorganisms, protecting them from harsh external environments and enriching specific bacterial species. ③ Promotion of electron transfer: Activated carbon has good electrical conductivity. Recent studies have found that it can act as an "electron conductor" between microbial cells or between cells and pollutants, promoting extracellular electron transfer and accelerating redox reactions (such as the oxidation of sulfides). ④ Regulates humidity and odor: It can absorb excess moisture and release it when dry, thus helping to regulate humidity; at the same time, it can also absorb its own metabolic intermediates to avoid secondary odors.

[0029] In this invention, the preparation method of the composite filter material may include the following steps: mixing ceramsite, volcanic rock, pine bark and activated carbon and filling them into polypropylene hollow spheres to obtain the composite filter material; this invention has no special requirements for the mixing, as long as it can be mixed evenly; this invention has no special requirements for the filling, and conventional methods in the art can be used.

[0030] The present invention allows the composite filter media in the composite filter layer to be replaced every 6 to 12 months, specifically every 8 months or 10 months.

[0031] In this invention, the biofilter bed can be provided with a sewage outlet, which can be connected to a gravity-flow sewage pipe.

[0032] In one specific embodiment of the present invention, a deodorizing agent nozzle is provided at the upper part of the deodorizing spray tower 3, and a second demister 32 is provided at the upper part of the deodorizing agent nozzle; the deodorizing agent nozzle is connected to the lower outlet of the deodorizing agent storage container 33 through a second delivery pump 34; the bottom outlet of the deodorizing spray tower 3 is connected to the top inlet of the deodorizing agent storage container 33; the deodorizing spray tower 3 is filled with packing material, which can be PP packing material; a level gauge is provided on the lower side of the deodorizing spray tower 3; the present invention can control the level of deodorizing agent in the deodorizing spray tower 3 by means of a float valve.

[0033] In one specific embodiment of the present invention, the deodorant storage container 33 is provided with a sewage outlet, which can be connected to a gravity sewage pipe; the deodorant solution formed by diluting the deodorant is stored in the deodorant storage container 33.

[0034] In one specific embodiment of the present invention, the diameter of the drain pipe can be 400 mm and the height can be 15 m; the material of the drain pipe can be SUS304, and the thickness of the SUS304 can be 1.2 mm. In another specific embodiment of the present invention, the drain pipe can be provided with a sampling port, through which sampling and detection can be performed.

[0035] In one specific embodiment of the present invention, the exhaust pipe 4 is provided with a sewage outlet, which can be connected to a gravity-flow sewage pipe.

[0036] Figure 1 This is a schematic diagram of the waste gas treatment system provided by the present invention.

[0037] This invention also provides the application of the waste gas treatment system described above in treating odorous gases generated from municipal solid waste landfills. In this invention, the odorous gas can be aerobic pretreatment tail gas from a municipal solid waste landfill, or gas collected from landfill gas collection wells in the municipal solid waste landfill.

[0038] This invention also provides a method for treating malodorous gases generated in municipal solid waste landfills, comprising the following steps: The malodorous gas generated from the municipal solid waste landfill is transported to the alkaline scrubbing spray tower 1 and subjected to alkaline scrubbing by counter-current contact with alkaline solution to obtain primary deodorized gas; The primary deodorized gas is transported to the biofilter 2 for biological deodorization to obtain secondary deodorized gas; the pressure drop of the biofilter during the biological deodorization operation is 500~1000Pa / m. The secondary deodorized gas is transported to the deodorization spray tower 3 and comes into counter-current contact with the deodorizing agent solution for deodorization, resulting in deodorized gas; The deodorized gas is then exhausted through exhaust pipe 4.

[0039] This invention transports malodorous gases generated from municipal solid waste landfills to an alkaline scrubbing tower 1, where they undergo counter-current alkaline scrubbing to obtain primary deodorized gases. In this invention, the malodorous gases include H2S, NH3, and VOCs; the concentration of H2S in the malodorous gases can be 5-200 ppm, specifically 134 ppm; the concentration of NH3 in the malodorous gases can be 50-400 ppm, specifically 350 ppm; and the concentration of VOCs in the malodorous gases can be 10-500 ppm, specifically 320 ppm. In this invention, the flow rate of the malodorous gases can be 1200-1300 m³ / h. 3 / h, which can be specifically 1250m 3 / h; the alkaline solution may include sodium hydroxide solution, and the pH value of the alkaline solution may be 11~13, specifically 12; the liquid-to-gas ratio of the alkaline washing may be 5~15 L / m 3 Specifically, it can be 8L / m 3 10L / m 3 Or 13L / m 3 This invention limits the liquid-to-gas ratio to within the above-mentioned range to balance mass transfer efficiency and energy consumption.

[0040] This invention removes some harmful gases, such as H2S and NH3, from malodorous gases during alkaline washing through physical absorption and neutralization chemical reactions via gas-liquid mass transfer. Specifically, when malodorous gases (H2S and NH3, etc.) pass through the packing layer, they come into full contact with the alkaline solution and dissolve in the liquid phase (solubility: H2S 0.1 mol / L, NH3 0.05 mol / L), forming "aerosol droplets." Hydrogen sulfide also undergoes a neutralization reaction with alkaline substances in the alkaline solution to remove a large amount of hydrogen sulfide. Taking sodium hydroxide solution as an example, the neutralization reaction is H2S + 2NaOH → Na2S2O3 + H2O.

[0041] After obtaining the primary deodorizing gas, this invention delivers the primary deodorizing gas to a biofilter bed 2 for biological deodorization to obtain secondary deodorizing gas. In this invention, the initial pressure drop of the filter bed during the initial process of biological deodorization is 100~300 Pa / m, specifically 150 Pa / m, 200 Pa / m, or 250 Pa / m; the pressure drop range of the biofilter bed during the biological deodorization operation is 500~1000 Pa / m, specifically 600 Pa / m, 700 Pa / m, 800 Pa / m, or 900 Pa / m; the flow rate of the primary deodorizing gas can be 1200~1300 m³ / h. 3 / h, which can be specifically 1250m 3The relative humidity of the biological deodorization environment can be 40-60%, specifically 45%, 50%, or 55%; the pH value of the biological deodorization environment can be 6.5-8.5, specifically 7 or 8; the temperature of the biological deodorization environment can be 20-30℃, specifically 25℃. This invention controls the growth of microorganisms by regulating the relative humidity, pH value, and temperature of the biological deodorization environment, thereby ensuring that the pressure drop of the biofilter bed remains within the above-mentioned ranges during the biological deodorization process.

[0042] In this invention, the functional microbial community used in the biological deodorization process may include one or more of sulfur-oxidizing bacteria, nitrifying bacteria, denitrifying bacteria, Bacillus, Pseudomonas, and yeast, specifically sulfur-oxidizing bacteria, nitrifying bacteria, denitrifying bacteria, Bacillus, Pseudomonas, and yeast. This invention, under the action of the functional microbial community, can degrade hydrogen sulfide, ammonia, and volatile organic compounds. The specific principle is as follows: H2S degradation: Sulfur-oxidizing bacteria (such as Thiobacillus) oxidize H2S to sulfate (SO4). 2- The process is H2S + 2O2 → SO4 2- +2H + NH3 degradation: Nitrifying bacteria (such as Nitrosomonas) oxidize NH3 to nitrite (NH3 + 1.5O2 → NO2). - +H + +H2O), which is then reduced to N2 (NO2) by denitrifying bacteria (such as Pseudomonas). - +0.5O2→NO3 - NO3 - +2H + +2e - →N2↑+H2O); the final products are N2 and H2O; VOCs degradation: heterotrophic bacteria (such as Bacillus, Pseudomonas, and yeast, etc.) oxidize VOCs (such as methanethiol) to CO2 and H2O (CH3SH+2O2→CO2+H2O+SO4) 2- The functional microbial community degrades the product, producing metabolites such as sulfate, nitrite, CO2, and N2, which can be excreted periodically (once a month).

[0043] The present invention achieves a biological deodorization efficiency of >90% for H2S and NH3, which can be 92-95%; a VOCs removal efficiency of >85%, which can be 88-92%; and an odor concentration (overall odor) removal rate of >85%, which can be 85-94%.

[0044] This invention involves an initial biological cultivation and acclimatization period (15-20 days) for biological deodorization. During the initial system activation (acclimatization), the biological inoculum and biological deodorizer (meeting the requirements of CJ / T516 "Technical Requirements for Deodorizers for Municipal Solid Waste") are added in a 1:2 ratio. This can be done two or more times, with the volume ratio of odorous gas to the weight ratio of the biological inoculum being approximately 100 m³. 3 The dosage is 1 kg, with a 3-day interval between two additions to ensure the survival rate of the microbial strains. When there is no air intake at the front end, to ensure the normal survival of the cultured strains, an organic carbon source (such as brown sugar) can be added every 5-7 days, with each addition weighing 2-3 kg. Once the biological deodorization system is operating normally, the odorous gas can provide an organic carbon source for the microorganisms, eliminating the need for additional carbon source additions.

[0045] After obtaining the secondary deodorized gas, this invention conveys the secondary deodorized gas to a deodorizing spray tower 3 for counter-current contact with the deodorizing agent solution to achieve deodorization, resulting in deodorized gas. In this invention, the flow rate of the secondary deodorized gas can be 1200~1300 m³ / h. 3 / h, which can be specifically 1250m 3 / h; the volume ratio of the secondary deodorizing gas to the mass ratio of the plant-based deodorizing agent can be 98~100m³. 3 1kg.

[0046] In this invention, the deodorizer in the deodorizer solution may include a plant-based deodorizer. This invention does not have special requirements for the plant-based deodorizer, as long as it meets the technical requirements for plant-based deodorizers in Table 5 of CJ / T516 "Technical Requirements for Deodorizers for Municipal Solid Waste". In this invention, the solvent in the deodorizer solution may be water, and the water may be deionized water. The volume ratio of the deodorizer to the solvent in the deodorizer solution may be 1~2:98~102, specifically 1:100 or 1:50.

[0047] In this invention, when the system is first activated, a plant-based deodorizer needs to be added once (the volume ratio of the odorous gas to the mass ratio of the plant-based deodorizer is approximately 100m³). 3 1 kg), dilute the plant deodorizer to form a deodorizer solution and then spray it; during the normal operation of the subsequent system, the dosage is 1~2 kg of plant deodorizer / h.

[0048] In this invention, the deodorized gas emissions are required to meet the corresponding requirement of "exhaust stack height 15m" in "Table 2 Odor Pollutant Emission Standard Values" of GB14554-1993.

[0049] Plant-based deodorizers are complex systems composed of various active ingredients extracted from plants; their deodorizing principle combines physical, chemical, and biological methods. The main principles can be categorized as follows: 1. Chemical Action (Dominant Principle): Acid-Base Neutralization Reaction: Many malodorous substances are acidic (e.g., hydrogen sulfide, lower fatty acids) or alkaline (e.g., ammonia, amines). Plant extracts contain organic acids (e.g., tannic acid, citric acid) or alkaloids, which can be converted into low-odor or odorless salts through neutralization reactions. Main Formulas: Removing Ammonia Odor (Neutralization): R-COOH (plant organic acid) + NH3 → R-COONH4 (odorless ammonium salt). Removing Hydrogen Sulfide Odor (Neutralization Oxidation): H2S + [O] (oxidizing components in plants) → S (or SO42-) 2- () + H₂O. Redox reaction: Polyphenols (such as tea polyphenols) and flavonoids in plants are good reducing agents and antioxidants, which can oxidize malodorous sulfides, aldehydes, etc., into harmless substances. Esterification / complexation reaction: Esterification or formation of stable complexes with certain malodorous molecules changes their molecular structure and eliminates odor.

[0050] 2. Physical effects Adsorption and Encapsulation: Macromolecules (such as pectin and polysaccharides) and surfactants in plant extracts can adsorb odor molecules or encapsulate them in micelles, reducing their volatilization into the air. Masking and Blending: The fresh aroma of the plants themselves can be used to sensorily mask and blend low concentrations of malodorous substances.

[0051] 3. Biological effects (auxiliary) Catalysis and Degradation: Certain plant enzymes (such as oxidoreductases) can catalyze the degradation of malodorous substances. Antibacterial Properties: Some plant essential oils (such as terpenes) have broad-spectrum antibacterial properties, which can inhibit the reproduction of malodorous bacteria (such as putrefactive bacteria), reducing the production of malodorous substances at the source. The chemical reaction formulas of the core deodorization process are characterized as follows: Removal of ammonia: R-COOH + NH3 → R-COONH4; (R represents plant organic acid groups); Removal of hydrogen sulfide: C6H4(OH)2 (catechins) + H2S C6H4O2 (o-benzoquinone) + S↓ + 2H2O; ([O] represents the oxidation conditions in the reaction system, and sulfur may be further oxidized to sulfate); Removal of formaldehyde and other aldehydes: R-CHO (formaldehyde, etc.) + R'-OH (plant polyphenols) → R-CH(OH)-OR' (hemiacetal or acetal).

[0052] After obtaining the deodorized gas, the present invention discharges the deodorized gas through the exhaust pipe 4.

[0053] In this invention, during normal operation, the alkaline washing spray tower and deodorizing agent spray tower can be inspected every month to check the cleanliness of the packing and demister inside the tower, as well as the blockage of the spray pipes and nozzles. If the packing and demister have clumps of dirt clogging the holes, they need to be cleaned and maintained to avoid affecting ventilation and odor treatment performance, or even damaging the equipment, due to blockage of the holes and accumulation of internal dirt. If the nozzles are blocked, they need to be disassembled and flushed to avoid poor spraying effect due to nozzle blockage, which would affect the deodorization effect.

[0054] During the operation of the alkaline scrubbing tower, the pH value of the alkaline solution can be manually tested with pH test strips every week to compare with the real-time detection data of the pH meter. If the test strip results differ significantly from the pH meter data, there may be a malfunction in the pH meter electrode probe or instrument, which requires repair or replacement.

[0055] After the microbial culture and acclimatization are completed, the equipment should not be shut down for extended periods, and the front end should not be without an air supply for microbial treatment for a long time. If the equipment is shut down for a long time (more than five days), the microbial culture inside the equipment may become inactive, leading to irreversible situations such as the caking of the composite filter media. If a short-term shutdown (less than five days) is required due to maintenance or other reasons, an appropriate amount of biological deodorizing liquid (20-25 kg / time recommended) and nutrient solution (organic carbon source, 5-8 kg / time recommended) can be added to the water tank. Ensure that the circulation pump can be started normally to ensure that the microbial culture attached to the composite filter media does not become inactive and that the composite filter media layer does not dry out and caking, thus minimizing the impact of shutdown on the activity of the microbial culture.

[0056] The sludge discharge of the alkaline scrubbing spray tower, biological filter bed, and deodorizing agent spray tower needs to be done manually. During system operation, the following specific procedures can be followed based on the operating conditions: ① The alkaline scrubbing spray tower should be maintained with a half-discharge every 10-15 days and a full discharge every 25-30 days. After a full discharge, the dosage should be the same as the initial dosing for equipment startup. ② The deodorizing agent spray tower should be maintained with a half-discharge every 25-30 days and a full discharge every 55-60 days. After a full discharge, the dosage should be the same as the initial dosing for equipment startup. ③ The biological filter bed should be maintained with a moderate sludge discharge (approximately 15-20% of the total liquid level) every 55-60 days. After the discharge, immediately add an appropriate amount of biological deodorizing liquid (20-25 kg / time) and nutrient solution (organic carbon source, 5-8 kg / time), and ensure the circulating pump is functioning properly.

[0057] During system operation, the first conveying circulation pump, the circulation pump, and the second conveying circulation pump can be checked regularly for leaks or malfunctions. If any malfunctions are found, repairs are required.

[0058] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0059] Example 1 according to Figure 2 The structure shown constructs an exhaust gas system. The packing material inside the alkaline scrubbing tower 1 has a specific surface area of ​​500 m². 2 / m 3 The PP packing material of the alkali washing spray tower 1 is SUS304 with a thickness of 1.5mm and a specification of [specification missing]. The dimensions are 1000×H3500mm; the flow passage of the first transfer pump 14 is made of fiber-reinforced polypropylene with a power of 0.75kW; the dimensions of the biological filter bed are 4000×2000×1500mm, and two baffles with a height of 1m are installed in the biological filter bed; the outer shell of the biological filter bed is made of SUS304 with a thickness of 2.0mm, and the flow passage of the circulation pump is made of fiber-reinforced polypropylene with a power of 2.2kW; the carrier of the composite filter media in the composite filter media layer is a polypropylene hollow sphere with a diameter of 100mm; by mass percentage, the active component of the composite filter media includes 40% ceramsite (ceramsite with a particle size greater than or equal to 4mm and less than 6mm has a mass percentage of 40%). The composite filter media consists of 60% ceramsite with a particle size greater than or equal to 6mm and less than 8mm (by mass percentage), 30% volcanic rock with an average particle size of 8mm, 25% pine bark with a length of 25-35mm and a thickness of 3-10mm, and 5% bamboo charcoal with an average particle size of 5mm. The ceramsite, volcanic rock, pine bark, and activated carbon are mixed evenly according to the required mass ratio and then manually filled into hollow polypropylene spheres to obtain the composite filter media. This composite filter media is then filled into a biological filter bed. The flow passage of the second delivery pump 34 is made of fiber-reinforced polypropylene and has a power of 0.75kW. The discharge pipe has a diameter of 400mm and a height of 15m. The discharge pipe is made of SUS304 with a thickness of 1.2mm.

[0060] Taking the odorous gas generated from the aerobic pretreatment tail gas of the municipal solid waste landfill in Xuan'en County, Enshi Prefecture, Hubei Province as an example, this study investigates its treatment. The landfill in Xuan'en County, Enshi Prefecture, Hubei Province, no longer accepts fresh municipal solid waste; the existing waste is 8 to 20 years old. The concentration of H2S in the odorous gas from the aerobic pretreatment tail gas is approximately 134 ppm, NH3 is approximately 350 ppm, VOCs is approximately 320 ppm, and the odor concentration (dimensionless) is 5700. The odorous gas is then processed at a rate of 1200 m³ / h. 3 The flow rate is conveyed to alkaline washing spray tower 1 at a rate of / h, where it comes into countercurrent contact with a sodium hydroxide solution with a pH of 12 for alkaline washing (the liquid-to-gas ratio of alkaline washing is 5~15L / m). 3 ), to obtain primary deodorizing gas; The primary deodorizing gas is prepared at 1200m 3 The flow rate is / h and is delivered to the biofilter 2 for biological deodorization to obtain secondary deodorized gas; the pressure drop of the biofilter is 240Pa / m at the initial stage of operation and 850Pa / m during normal operation; the relative humidity of the biological deodorization environment is 40~60%, the pH value is 6.5~8.5, and the temperature is 20~30℃. The secondary deodorization gas is 1200m 3 A flow rate of / h is conveyed to the deodorization spray tower 3, where it comes into counter-current contact with a plant-based deodorizing agent solution (meeting the technical requirements for plant-based deodorizing agents in Table 5 of CJ / T516 "Technical Requirements for Deodorizing Agents for Municipal Solid Waste") to obtain deodorized gas; firstly, the volume ratio of the secondary deodorized gas to the mass ratio of the plant-based deodorizing agent is 100m³ / h. 3 Add 1 kg of plant-based deodorant. During operation, the dosage of plant-based deodorant is 1-2 kg / h. Mix the plant-based deodorant and deionized water at a volume ratio of 1:100 to obtain a deodorant solution. The deodorized gas is then exhausted through exhaust pipe 4.

[0061] According to the method in "Table 3 Determination Method of Odor Pollutant and Odor Concentration" of the "Odor Pollutant Emission Standard" (GB14554-1993), the content of H2S, NH3, VOCs and odor in the deodorized gas was detected (H2S concentration was 6 ppm, NH3 concentration was 21 ppm, VOCs concentration was 29 ppm, and odor concentration (dimensionless) was 456). The removal efficiency was calculated as follows: H2S removal efficiency was 96%, NH3 removal efficiency was 94%, VOCs removal efficiency was 91%, and odor removal efficiency was 92%.

[0062] As can be seen from the test results of the embodiments, the exhaust gas treatment system provided by the present invention can effectively remove H2S, NH3 and VOCs from the odorous gases generated by municipal solid waste landfills. Furthermore, the exhaust gas treatment system provided by the present invention is sealed and not prone to leakage, which can reduce secondary pollution.

[0063] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A waste gas treatment system, characterized in that, It includes an alkaline scrubbing spray tower (1), a biofilter (2) with a bottom first gas inlet (21) connected to the top outlet (15) of the alkaline scrubbing spray tower, a deodorizing spray tower (3) with a bottom second gas inlet (31) connected to the top outlet (23) of the biofilter tower, and an exhaust pipe (4) connected to the top outlet (35) of the deodorizing spray tower.

2. The waste gas treatment system according to claim 1, characterized in that, The lower part of the alkaline scrubbing tower (1) is provided with an exhaust gas inlet (11), and the upper part of the alkaline scrubbing tower (1) is provided with an alkaline spray head. The upper part of the alkaline spray head is provided with a first demister (12). The alkaline spray head is connected to the lower outlet of the alkaline storage container (13) through a first delivery pump (14). The bottom outlet of the alkaline scrubbing tower (1) is connected to the top inlet of the alkaline storage container (13). The alkaline washing spray tower (1) is equipped with packing material; a level gauge is installed on the lower side of the alkaline washing spray tower (1).

3. The waste gas treatment system according to claim 1, characterized in that, The biofilter bed (2) is provided with a composite filter media layer, a pH meter, a level gauge and a circulation device; the circulation device includes a humidifying nozzle located on the upper part of the composite filter media layer, and the humidifying nozzle is connected to the nutrient solution at the bottom of the biofilter bed through a circulation pump (22).

4. The waste gas treatment system according to claim 3, characterized in that, The composite filter media in the composite filter media layer includes an active component and a carrier, wherein the carrier is a hollow polypropylene sphere. The active component comprises the following components in mass percentage: 35-45% expanded clay aggregate; 25-32% volcanic rock; 23-28% pine bark; Activated carbon 4-6%.

5. The waste gas treatment system according to claim 1, characterized in that, The upper part of the deodorizing spray tower (3) is provided with a deodorizing agent nozzle, and the upper part of the deodorizing agent nozzle is provided with a second demister (32); the deodorizing agent nozzle is connected to the lower outlet of the deodorizing agent storage container (33) through a second delivery pump (34); the bottom outlet of the deodorizing spray tower (3) is connected to the top inlet of the deodorizing agent storage container (33); The deodorizing spray tower (3) is equipped with packing material; a level gauge is installed on the lower side of the deodorizing spray tower (3).

6. The application of the waste gas treatment system according to any one of claims 1 to 5 in treating malodorous gases generated in municipal solid waste landfills.

7. A method for treating malodorous gases generated in a municipal solid waste landfill, characterized in that, Includes the following steps: The malodorous gas generated from the municipal solid waste landfill is transported to the alkaline scrubbing tower (1) and subjected to alkaline scrubbing in reverse contact with alkaline solution to obtain primary deodorized gas; The primary deodorizing gas is transported to the biofilter (2) for biological deodorization to obtain secondary deodorizing gas; the pressure drop of the biofilter during the biological deodorization operation is 500~1000Pa / m. The secondary deodorized gas is transported to the deodorization spray tower (3) and deodorized by counter-current contact with the deodorizing agent solution to obtain deodorized gas; The deodorized gas is discharged through the exhaust pipe (4).

8. The processing method according to claim 7, characterized in that, The flow rate of the malodorous gas is 1200~1300 m³ / h. 3 / h; The alkaline solution includes a sodium hydroxide solution, and the pH value of the alkaline solution is 11-13; The liquid-to-gas ratio of the alkaline washing is 5~15 L / m³. 3 .

9. The processing method according to claim 7, characterized in that, The functional microbial community used in the biological deodorization includes one or more of the following: sulfur bacteria, nitrifying bacteria, denitrifying bacteria, Bacillus, Pseudomonas, and yeast. The flow rate of the primary deodorizing gas is 1200~1300 m³ / h. 3 / h; The relative humidity of the biological deodorization environment is 40-60%, the pH value is 6.5-8.5, and the temperature is 20-30℃.

10. The processing method according to claim 7, characterized in that, The deodorant in the deodorant solution includes plant-based deodorants; The flow rate of the secondary deodorizing gas is 1200~1300 m³ / h. 3 / h, the volume ratio of the secondary deodorizing gas to the mass ratio of the plant-based deodorizing agent is 98~100m³. 3 1kg.

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