VOCs waste gas adsorption and desorption treatment system and treatment method

Abstract

The invention provides a VOCs waste gas adsorption and desorption treatment system and method. According to the invention, the microbial liquid composed of specific microbial agents enters the waste gas adsorption and desorption tower body, and organic matters adsorbed by a solid adsorbent can be efficiently decomposed without any manual operation intervention and addition of chemical agents, so that the functions of adsorption and desorption can be simultaneously completed in one tower body, and the waste gas adsorption and desorption efficiency is improved. High-energy-consumption decomposition or desorption devices such as high-temperature combustion and hot steam do not need to be additionally arranged, so that the operation cost of the waste gas treatment system is greatly reduced, and the treatment flow is also greatly simplified; high-concentration waste gas cannot be generated in the desorption process, so that the operation risk is reduced; the used microbial bacteria are nontoxic and harmless, and organic matters in the waste gas are decomposed into carbon dioxide and water, so that the whole waste gas treatment process is more environment-friendly, and secondary harmful substances are not generated.

Description

Technical Field

[0001] This invention belongs to the field of environmental engineering technology, specifically relating to a VOCs waste gas adsorption-desorption treatment system and treatment method. Background Technology

[0002] In industries such as printing, coating, chemical, and electronics manufacturing, the treatment of low-to-medium concentration, intermittent volatile organic compound (VOC) emissions has always been a challenge in environmental governance. Traditional single-treatment technologies (such as direct combustion or adsorbent adsorption) suffer from high energy consumption, high operating costs, or secondary pollution. The synergistic effect of a combined process of "adsorption concentration + thermal desorption + catalytic combustion" using adsorbents (activated carbon, molecular sieves, or resins) has achieved the purification of low-concentration emissions, becoming the mainstream technology for treating low-to-medium concentration emissions.

[0003] Compared with traditional single treatment processes, the combined treatment process has reduced energy consumption and operating costs, but still has the following problems: (1) The adsorbent needs to use steam or hot air as a heat source for thermal desorption and regeneration. The reaction temperature of catalytic combustion is 200-300°C, and auxiliary fuel natural gas or electric heaters are needed to maintain the reaction temperature. Therefore, the energy consumption is still very high in operating costs. (2) When the saturated adsorbent is desorbed under the action of the heat source, it will produce high-concentration waste gas. It is necessary to strictly control the waste gas concentration within 25% LEL to prevent explosion. For waste gas with complex composition, it is difficult to accurately control the desorption rate, which often leads to explosion accidents. (3) For intermittently emitted waste gas, the heating device of the catalytic combustion equipment needs to be turned on 2-3 hours in advance. When the waste gas enters the catalytic combustion equipment, the temperature is 200-300°C to ensure a high VOCs removal efficiency. In addition to increasing energy consumption, the operation is inconvenient and cannot respond to the waste gas emitted by the production line at any time. Summary of the Invention

[0004] In view of the shortcomings of existing technologies, the purpose of this invention is to provide a novel VOCs waste gas adsorption and desorption treatment system to solve the problems of high operating costs, high safety risks, inconvenient operation and slow response of existing VOCs waste gas treatment processes with medium and low concentrations and intermittent production.

[0005] Another object of the present invention is to provide a VOCs waste gas adsorption and desorption treatment method using the above-mentioned VOCs waste gas adsorption and desorption treatment system.

[0006] To achieve the above objectives, the solution adopted by the present invention is as follows: In a first aspect, the present invention provides a VOCs waste gas adsorption and desorption treatment system, comprising a waste gas adsorption and desorption device, a bacterial growth device, a drying device, and an exhaust device; wherein, The waste gas adsorption-desorption device includes at least two waste gas adsorption-desorption towers connected in series or in parallel. The waste gas adsorption-desorption towers are filled with solid adsorbent. Each waste gas adsorption-desorption tower is provided with a first inlet pipe and a first outlet pipe. The first inlet pipes of each waste gas adsorption-desorption tower are connected and converged into a total first inlet pipe. VOCs waste gas is introduced from the total first inlet pipe. The first outlet pipe of the waste gas adsorption-desorption tower is connected to the inlet of the exhaust device. The outlet of the exhaust device is connected to the atmosphere. The bacterial liquid growth device includes a bacterial liquid tank containing microbial bacterial liquid. Each waste gas adsorption-desorption tower is provided with an inlet pipe and an outlet pipe, which are respectively connected to the bacterial liquid tank. Each waste gas adsorption-desorption tower is equipped with a second inlet pipe and a second outlet pipe. The second inlet pipe of the waste gas adsorption-desorption tower is connected to the outlet of the drying device and is used to dry the solid adsorbent in the waste gas adsorption-desorption tower. The second outlet pipe of the waste gas adsorption-desorption tower is connected to the inlet of the exhaust device and is used to discharge the dried gas to the exhaust device.

[0007] Preferably, the solid adsorbent is selected from one or more of activated carbon, zeolite molecular sieves and resins, and the microbial inoculum is an agronomic microbial inoculum.

[0008] Preferably, each waste gas adsorption-desorption tower body has a first inlet pipe valve on its first inlet pipe, a second inlet pipe valve on its second inlet pipe, a first outlet pipe valve on its first outlet pipe, a second outlet pipe valve on its second outlet pipe, a liquid inlet pipe valve on its liquid inlet pipe, and an outlet pipe valve on its liquid outlet pipe.

[0009] Preferably, the first and second air inlet pipes on each waste gas adsorption-desorption tower are located at the bottom of the waste gas adsorption-desorption tower, the first and second air outlet pipes on each waste gas adsorption-desorption tower are located at the top of the waste gas adsorption-desorption tower, the liquid inlet pipe on each waste gas adsorption-desorption tower is located at the top of the waste gas adsorption-desorption tower, and the liquid outlet pipe on each waste gas adsorption-desorption tower is located at the bottom of the waste gas adsorption-desorption tower.

[0010] Preferably, the first inlet pipes on each of the exhaust gas adsorption-desorption towers are connected and converged into a total first inlet pipe, through which VOCs exhaust gas is introduced.

[0011] Preferably, the bacterial liquid growth device further includes a bacterial liquid delivery pump, an aeration blower, an aeration duct, a dosing pipe, a maintenance agent dosing pump, and a tap water pipe; wherein, the bacterial liquid delivery pump is located on the path of the main inlet pipe formed by the connection of the inlet pipes on each of the waste gas adsorption-desorption towers, the aeration blower is located outside the bacterial liquid tank and connected to one end of the aeration duct, the other end of the aeration duct enters the bacterial liquid tank from the bottom, the dosing pipe and the tap water pipe both enter the bacterial liquid tank from the top, and the maintenance agent dosing pump is located on the path of the dosing pipe.

[0012] Preferably, the drying device includes a heater and a drying fan. The heater is an air heater or an electric heater. The drying fan is connected to the inlet of the heater. The second air inlet pipes on each of the exhaust gas adsorption-desorption towers are connected to form a total second air inlet pipe, which is connected to the outlet of the heater.

[0013] Preferably, the exhaust device includes an exhaust fan and an exhaust stack. The first exhaust pipes on each exhaust gas adsorption-desorption tower are connected and converged into a main exhaust pipe. The second exhaust pipes on each exhaust gas adsorption-desorption tower are connected and converged into the main exhaust pipe. The main exhaust pipe is connected to the inlet of the exhaust fan, the outlet of the exhaust fan is connected to the inlet of the exhaust stack, and the outlet of the exhaust stack is connected to the atmosphere. The exhaust fan is a negative pressure control exhaust device, used to control the exhaust gas adsorption-desorption tower to be in a negative pressure state throughout the entire exhaust gas treatment process.

[0014] Preferably, it also includes a PLC automatic control device, which is electrically connected to each valve, bacterial liquid delivery pump, aeration fan, maintenance agent dosing pump, heater, drying fan and exhaust fan, and is used to control their opening and closing.

[0015] Secondly, the present invention also provides a VOCs waste gas adsorption and desorption treatment method, which employs the VOCs waste gas adsorption and desorption treatment system described above, and includes the following steps: (1) First, enter the adsorption mode, open the first inlet valve of one or more waste gas adsorption and desorption towers, and introduce the VOCs waste gas to be treated into the waste gas adsorption and desorption tower through the main first inlet pipe. After the waste gas is adsorbed by the solid adsorbent in the waste gas adsorption and desorption tower, the organic matter is adsorbed into the solid adsorbent. Then, open the first outlet valve of the waste gas adsorption and desorption tower, start the exhaust device, and the waste gas after adsorption treatment is discharged from the first outlet pipe on the waste gas adsorption and desorption tower and discharged into the atmosphere through the exhaust device. (2) After one or more waste gas adsorption-desorption towers are saturated with adsorption, the desorption mode is entered. Microbial liquid from the bacterial liquid tank is introduced into the waste gas adsorption-desorption tower until the microbial liquid covers the entire solid adsorbent. Without any manual intervention or addition of chemical agents, the microbial liquid decomposes the organic matter adsorbed in the solid adsorbent into carbon dioxide and water, so that the solid adsorbent regains its adsorption capacity. The microbial liquid consists of sterile water and microbial strains. The microbial strains are obtained by separating, purifying and screening *Bacillus baileyi* (LM-W, accession number: CGMCC No. 17168) and *Bacillus brevis* (LM-R, accession number: CGMCC) from the bottom sludge of spray paint wastewater. Composition No. 17167); In the regenerated bacterial solution, the bacterial concentration of *Bacillus baileyi* is 5-50 million CFU / ml, the bacterial concentration of *Bacillus brevis* is 5-50 million CFU / ml, and the colony count ratio of *Bacillus baileyi* to *Bacillus brevis* is 1:(1-5). (3) After desorption is completed, open the liquid outlet valve of the waste gas desorption tower body so that all the microbial liquid in the waste gas desorption tower body is discharged and returned to the liquid tank; (4) Then enter the drying mode to dry the moisture in the solid adsorbent in the waste gas adsorption-desorption tower, so that the solid adsorbent is kept dry. The waste gas adsorption-desorption tower completes desorption and regeneration and enters the adsorption ready mode, which can be put into adsorption at any time. (5) The dried gas in the exhaust gas desorption tower is discharged to the exhaust device and discharged into the atmosphere.

[0016] Preferably, three or more waste gas adsorption-desorption towers are set up, and the opening and closing of each valve is controlled by a PLC automatic control device to switch between adsorption mode, desorption mode and drying mode for the three or more waste gas adsorption-desorption towers.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: The VOCs waste gas adsorption-desorption treatment system and method provided by this invention uses a microbial liquid composed of specific microbial agents to enter the waste gas adsorption-desorption tower. Without any manual intervention or addition of chemical agents, it can efficiently decompose the organic matter adsorbed by the solid adsorbent, thus achieving the simultaneous adsorption and desorption functions in one tower. This eliminates the need for additional energy-intensive desorption devices such as high-temperature combustion or hot steam, significantly reducing the cost of the waste gas treatment system and greatly simplifying the treatment process. No high-concentration waste gas is generated during the desorption process, reducing operation and maintenance risks. The microorganisms used are non-toxic and harmless, decomposing the organic matter in the waste gas into non-toxic and harmless carbon dioxide and water, making the entire waste gas treatment process more environmentally friendly and preventing the generation of secondary harmful substances. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the VOCs waste gas adsorption and desorption treatment system involved in the present invention. Detailed Implementation

[0019] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0020] like Figure 1 As shown, the present invention provides a VOCs waste gas adsorption and desorption treatment system, including a waste gas adsorption and desorption device 100, a bacterial liquid growth device 200, a drying device 300, and an exhaust device 400.

[0021] Specifically, in the VOCs waste gas adsorption and desorption treatment system provided by the present invention, the waste gas adsorption and desorption device 100 used in the present invention includes at least two waste gas adsorption and desorption towers 110 connected in series or in parallel. The waste gas adsorption and desorption towers 110 are filled with solid adsorbent. Each waste gas adsorption and desorption tower 110 is provided with a first inlet pipe 111 and a first outlet pipe 112. The first inlet pipe 111 is used to introduce the VOCs waste gas to be treated, and the first outlet pipe 112 is connected to the inlet of the exhaust device 400. The outlet of the exhaust device 400 is connected to the atmosphere.

[0022] In some embodiments, the first inlet pipes 111 on each of the exhaust gas adsorption-desorption tower bodies 110 are connected and merged into a total first inlet pipe 111a, through which VOCs exhaust gas is introduced.

[0023] According to the present invention, the solid adsorbent used in the present invention includes, but is not limited to, activated carbon, zeolite molecular sieves, or resin. The VOCs waste gas to be treated is introduced into the waste gas adsorption-desorption tower 110 through the main first inlet pipe 111a. The organic matter in the waste gas is adsorbed into the solid adsorbent of the waste gas adsorption-desorption tower 110, thereby achieving the purpose of purifying the VOCs waste gas. This adsorption purification process should be carried out in accordance with commonly known techniques, and will not be elaborated further here.

[0024] In the VOCs waste gas adsorption-desorption treatment system provided by the present invention, the exhaust device 400 used in the present invention includes a waste gas fan 410 and an exhaust stack 420. The first outlet pipes 112 on each waste gas adsorption-desorption tower 110 are connected and converged into a total outlet pipe 112a. The total outlet pipe 112a is connected to the inlet of the waste gas fan 410, the outlet of the waste gas fan 410 is connected to the inlet of the exhaust stack 420, and the outlet of the exhaust stack 420 is connected to the atmosphere. The VOCs waste gas to be treated is introduced into the waste gas adsorption-desorption tower 110 through the first inlet pipe 111a. The organic matter in the waste gas is adsorbed into the solid adsorbent of the waste gas adsorption-desorption tower 110. The waste gas after adsorption treatment is discharged from the first outlet pipe 112 on the waste gas adsorption-desorption tower 110 and discharged to the atmosphere through the exhaust device 400. In some embodiments, the exhaust fan 410 of the exhaust device 400 is a negative pressure control exhaust device. This setting can ensure that the exhaust gas adsorption-desorption tower 110 is always in a negative pressure state of -100Pa to -500Pa throughout the entire exhaust gas treatment process, and no exhaust gas will enter the environment. Finally, the treated exhaust gas is discharged into the atmosphere through the exhaust stack 420.

[0025] In the VOCs waste gas adsorption-desorption treatment system provided by the present invention, the bacterial liquid growth device 200 used in the present invention includes a bacterial liquid tank 210, which contains microbial liquid. Each waste gas adsorption-desorption tower 110 is provided with an inlet pipe 113 and an outlet pipe 114. The inlet pipes 113 on each waste gas adsorption-desorption tower 110 are connected to form a total inlet pipe 113a, and the outlet pipes 114 on each waste gas adsorption-desorption tower 110 are connected to form a total outlet pipe 114a. The total inlet pipe 113a and the total outlet pipe 114a are respectively connected to the bacterial liquid tank 210.

[0026] Specifically, the inlet pipe of the exhaust gas desorption tower is connected to the outlet of the bacterial liquid tank transfer pump for supplying bacterial liquid to the exhaust gas desorption tower, and the outlet pipe of the exhaust gas desorption tower is connected to the return port of the bacterial liquid tank for transporting the bacterial liquid in the exhaust gas desorption tower back to the bacterial liquid tank.

[0027] According to the present invention, the microbial liquid used is an aerobic microbial liquid. After the solid adsorbent in the waste gas adsorption-desorption tower 110 adsorbs organic matter in the waste gas to saturation, the microbial liquid in the liquid tank 210 is injected into the saturated waste gas adsorption-desorption tower 110 through the main inlet pipe 113a. The solid adsorbent in the waste gas adsorption-desorption tower 110 is completely immersed in the microbial liquid. The microbial liquid decomposes the organic matter adsorbed in the solid adsorbent into carbon dioxide and water, so that the solid adsorbent regains its adsorption capacity, thereby achieving the purpose of regeneration and desorption of the solid adsorbent in the waste gas adsorption-desorption tower 110.

[0028] According to the present invention, microbial strains are used to degrade and desorb organic matter attached to a saturated solid adsorbent, thereby regenerating the solid adsorbent. The regeneration process can be understood as follows: First, the organic compounds released from the solid adsorbent into the solution are degraded by microorganisms, resulting in a decrease in the concentration of organic matter in the solution, creating a concentration gradient between the surface of the solid adsorbent and the liquid phase, further promoting the desorption of the adsorbate; second, the exonucleases produced by the microorganisms diffuse into the micropores of the solid adsorbent and react with the adsorbate, thereby hydrolyzing or desorbing pollutants, decomposing the organic matter on the solid adsorbent into water, carbon dioxide, and inorganic matter, thus completing the biological regeneration process of the solid adsorbent. According to the present invention, the aerobic microbial inoculum used in the present invention is a specific microbial strain, specifically *Baiyelinkia* obtained by separation, purification, and screening of sediment from spray paint wastewater. Beijerinckia sp. LM-W, accession number: CGMCC No. 17168) and / or Bacillus brevis ( Brachymonas sp. Composed of LM-R (accession number: CGMCC No.17167).

[0029] According to the present invention, the present invention uses *Baiyelinkie* (a type of bacteria) obtained by separation, purification, and screening of sediment from spray paint wastewater. Beijerinckia sp. LM-W, accession number: CGMCC No. 17168) and / or Bacillus brevis ( Brachymonas sp. The regenerative bacterial solution composed of LM-R (accession number: CGMCC No. 17167) is used to regenerate the solid adsorbent in the saturated waste gas adsorption-desorption tower 110. Compared with conventional Bacillus baileyi or Bacillus brevis, it has a stronger decomposition and desorption performance for organic matter in the solid adsorbent in the saturated waste gas adsorption-desorption tower 110. Without any manual intervention or addition of chemical agents, the microbial strains can decompose and desorb the organic matter in the saturated solid adsorbent on their own. The entire decomposition and desorption time is only 60-84 hours, and the regeneration rate can reach 90%~95%. Thus, the adsorption and desorption functions can be completed simultaneously in one tower, without the need to add high-energy-consuming desorption devices such as high-temperature combustion or hot steam. This greatly reduces the cost and operation and maintenance risks of the waste gas treatment system. The microbial strains used are non-toxic and harmless, decomposing the organic matter in the waste gas into non-toxic and harmless carbon dioxide and water, making the entire waste gas treatment process more environmentally friendly and without producing secondary harmful substances.

[0030] According to the present invention, the present invention uses *Bacillus baileyi* (…). Beijerinckia sp. LM-W, accession number: CGMCC No.17168) and Bufota brevis ( Brachymonas sp.The samples (LM-R, CGMCC No. 17167) were all derived from the separation, purification, and screening of paint spraying wastewater sludge, such as sludge from exhaust gas scrubbing wastewater in automotive paint spraying booths.

[0031] According to the present invention, the present invention uses *Bacillus baileyi* (…). Beijerinckia sp. The method for obtaining LM-W (CGMCC No. 17168) includes the following steps: Take 10g from the bottom sludge of the exhaust gas scrubbing wastewater from an automotive paint spraying booth. Under aseptic conditions, add the 10g sample to a 250mL Erlenmeyer flask containing 100mL of sterile liquid enrichment medium (including 5g, 10g, 20g, 30g, or 50g of acrylic acid for acclimatization and enrichment, 0.1g of CaCl2·6H2O, 0.25g of MgCl2, 1.5g of K2HPO4, 1g of NH4Cl, 9g of peptone, 500mL of H2O, pH=6.5~7.0). After incubating for 7 days on a shaker at 30°C and 180rpm, transfer the 10% inoculum to the next batch of enrichment medium (acrylic acid gradient of 5, 10, 20, 30, or 50g / L) and acclimatize for another 7 days under the same conditions. Then, at a 10% inoculum volume, transfer the culture to a sterile liquid basal medium containing 100 g / L acrylic acid (including 1.00 g NH4NO3, 0.5 g MgSO4·7H2O, 0.5 g (NH4)2SO4, 0.5 g KH2PO4, 0.5 g NaCl, 1.5 g K2HPO4, 1000 mL H2O, pH=4.0), i.e., an acrylic acid concentration of 100 g / L basal medium. Continue culturing for 7 days. After two consecutive transfers, take 0.1 mL of the obtained fermentation broth and repeatedly streak it on a solid basal medium for separation and purification until a single colony is obtained. Inoculate the pure colony onto an agar slant and store it in a refrigerator at 40°C to obtain the final product.

[0032] According to the present invention, the present invention uses *Bacillus brevis* (…). Brachymonas sp. The method for obtaining LM-R (accession number: CGMCC No. 17167) includes the following steps: Take 10g from the bottom sludge of the exhaust gas scrubbing wastewater from an automotive paint spraying booth. Under aseptic conditions, add it to 250mL Erlenmeyer flasks containing 100mL of sterile liquid enrichment medium (including 5g, 10g, 20g, 30g, or 50g toluene for acclimatization and enrichment, 0.1g CaCl2·6H2O, 0.25g MgCl2, 1.5g K2HPO4, 1g NH4Cl, 9g peptone, 500mL H2O, pH=6.5~7.0). After incubating on a shaker at 30°C and 180rpm for 7 days, transfer it to the next batch of enrichment medium at a 10% inoculum (toluene gradient of 5, 10, 20, 30, or 50g / L) and acclimatize under the same conditions for 7 days. Then, at a 10% inoculum volume, transfer the culture to a sterile liquid basal medium containing 100 g / L toluene (including 1.00 g NH4NO3, 0.5 g MgSO4·7H2O, 0.5 g (NH4)2SO4, 0.5 g KH2PO4, 0.5 g NaCl, 1.5 g K2HPO4, 1000 mL H2O, pH=4.0), i.e., a basal medium with a toluene concentration of 100 g / L. Continue culturing for 7 days. After two consecutive transfers, take 0.1 mL of the obtained fermentation broth and repeatedly streak it on a solid basal medium for separation and purification until a single colony is obtained. Inoculate the pure colony onto an agar slant and store it in a refrigerator at 40°C to obtain the final product.

[0033] According to the present invention, the microbial strain used is *Baiyelinkie*, obtained by separation, purification, and screening of sediment from spray paint wastewater. Beijerinckia sp. LM-W, accession number: CGMCC No.17168) and Bufota brevis ( Brachymonas sp. The composite strain composed of LM-R (accession number: CGMCC No. 17167) exhibits synergistically enhanced decomposition and desorption performance on organic matter in saturated solid adsorbents, with a higher regeneration rate than that of a single strain.

[0034] According to the present invention, the above-mentioned composite microbial strain is dissolved in sterile water to prepare a microbial solution. In the regenerated solution, the bacterial concentration of *Bacillus baileyi* is 5-50 million CFU / ml, the bacterial concentration of *Bacillus brevis* is 5-50 million CFU / ml, and the colony count ratio of *Bacillus baileyi* to *Bacillus brevis* is 1:(1-5), for example, 1:2, 1:3, 1:4, etc. More preferably, when the colony count ratio of *Bacillus baileyi* to *Bacillus brevis* is 1:2, the composite microbial strain has stronger decomposition and desorption performance on organic matter in the adsorbed saturated solid adsorbent, and the regeneration rate is higher.

[0035] In the VOCs waste gas adsorption and desorption treatment system provided by the present invention, the bacterial liquid growth device 200 used in the present invention further includes a bacterial liquid delivery pump 220, an aeration fan 230, an aeration duct 240, a dosing pipe 250, a maintenance agent dosing pump 260, and a tap water pipe 270.

[0036] Specifically, the bacterial liquid transfer pump 220 is installed on the path of the total inlet pipe 113a formed by the inlet pipes 113 on each of the exhaust gas adsorption-desorption tower bodies 110. The microbial liquid in the bacterial liquid tank 210 is input into the exhaust gas adsorption-desorption tower body 110 through the bacterial liquid transfer pump 220.

[0037] Specifically, the aeration blower 230 is located outside the bacterial liquid tank 210 and connected to one end of the aeration pipe 240. The other end of the aeration pipe 240 enters the bacterial liquid tank 210 from the bottom.

[0038] According to the present invention, during the decomposition and desorption process of the exhaust gas adsorption-desorption tower 110, the aeration fan 230 is kept running continuously. The aeration fan 230 aerates the microbial liquid in the bacterial liquid tank 210, providing sufficient oxygen for the microbial liquid in the bacterial liquid tank 210 to decompose organic matter. The dissolved oxygen content of the microbial liquid in the bacterial liquid tank 210 is preferably maintained at 2-6 mg / L.

[0039] Specifically, both the dosing pipe 250 and the water pipe 270 connect to the top of the bacterial solution tank 210. The maintenance agent dosing pump 260 is located on the connection path of the dosing pipe 250. During the decomposition and desorption process in the exhaust gas adsorption-desorption tower 110, nutrients are added to the bacterial solution tank 210 at regular intervals and in measured quantities by the maintenance agent dosing pump 260 to maintain the microbial activity of the bacterial solution in the tank 210 at its optimal state. Water is automatically replenished through the water pipe 270 to maintain the liquid level in the bacterial solution tank 210. (Note: Only water needs to be added; fresh bacterial solution is not required.) In the VOCs exhaust gas adsorption-desorption treatment system provided by the present invention, the liquid outlet pipes 114 on each exhaust gas adsorption-desorption tower 110 are connected and converged into a total liquid outlet pipe 114a, which is connected to the bacterial liquid tank 210.

[0040] According to the present invention, the microbial liquid in the exhaust gas adsorption-desorption tower 110 decomposes the organic matter adsorbed in the solid adsorbent into carbon dioxide and water, so that the solid adsorbent can regain its adsorption capacity. Then, the microbial liquid in the exhaust gas adsorption-desorption tower is discharged through the liquid outlet pipe 114 and returned to the liquid tank 210 through the main liquid outlet pipe 114a until all the microbial liquid in it is discharged.

[0041] In the VOCs exhaust gas adsorption and desorption treatment system provided by the present invention, the drying device 300 used in the present invention includes a heater 310 and a drying fan 320, wherein the heater 310 is, for example, an air heater or an electric heater.

[0042] According to the present invention, each exhaust gas adsorption-desorption tower 110 is also provided with a second air inlet pipe 115. The second air inlet pipes 115 on each exhaust gas adsorption-desorption tower 110 are connected and merged into a total second air inlet pipe 115a. The total second air inlet pipe 115a is connected to the outlet of the drying device 300. Specifically, the total second air inlet pipe 115a is connected to the outlet of the heater 310 of the drying device 300, and the inlet of the heater 310 is connected to the drying fan 320. After the solid adsorbent inside the waste gas adsorption-desorption tower 110 is decomposed and desorbed by the input of microbial liquid, the drying device 300 is turned on, and the external air is drawn into the heater 310 by the drying fan 320 for heating. The hot air at 40-80°C is drawn into the waste gas adsorption-desorption tower 110 through the main second air inlet pipe 115a and the second air inlet pipe 115 to dry the moisture in the solid adsorbent in the waste gas adsorption-desorption tower, so that the solid adsorbent is kept in a dry state and the regeneration of the solid adsorbent is completed.

[0043] According to the present invention, each waste gas adsorption-desorption tower 110 is also provided with a second outlet pipe 116. The second outlet pipes 116 on each waste gas adsorption-desorption tower 110 are connected and converged to the main outlet pipe 112a. The main outlet pipe 112a is connected to the inlet of the exhaust device 400. After the solid adsorbent in the waste gas adsorption-desorption tower is dried by the drying device 300, and the temperature of the solid adsorbent drops below 40°C, the gas after the solid adsorbent in the waste gas adsorption-desorption tower 110 is discharged to the exhaust device 400 through the second outlet pipe 116 and the main outlet pipe 112a. Specifically, the main outlet pipe 112a is connected to the inlet of the waste gas fan 410, the outlet of the waste gas fan 410 is connected to the inlet of the exhaust stack 420, and the outlet of the exhaust stack 420 is connected to the atmosphere. The gas after the solid adsorbent in the waste gas adsorption-desorption tower 110 is finally discharged to the atmosphere.

[0044] In the VOCs exhaust gas adsorption-desorption treatment system provided by the present invention, the first inlet pipe 111 and the second inlet pipe 115 on each exhaust gas adsorption-desorption tower 110 are both located at the bottom of the exhaust gas adsorption-desorption tower 110, the first outlet pipe 112 and the second outlet pipe 116 on each exhaust gas adsorption-desorption tower 110 are both located at the top of the exhaust gas adsorption-desorption tower 110, the liquid inlet pipe 113 on each exhaust gas adsorption-desorption tower 110 are both located at the top of the exhaust gas adsorption-desorption tower 110, and the liquid outlet pipe 114 on each exhaust gas adsorption-desorption tower 110 are both located at the bottom of the exhaust gas adsorption-desorption tower 110.

[0045] In the VOCs exhaust gas adsorption-desorption treatment system provided by the present invention, a first inlet valve 117 is provided on the first inlet pipe 111 of each exhaust gas adsorption-desorption tower 110, a second inlet valve 118 is provided on the second inlet pipe 115 of each exhaust gas adsorption-desorption tower 110, a first outlet valve 119 is provided on the first outlet pipe 112 of each exhaust gas adsorption-desorption tower 110, a second outlet valve 120 is provided on the second outlet pipe 116 of each exhaust gas adsorption-desorption tower 110, a liquid inlet valve 121 is provided on the liquid inlet pipe 113 of each exhaust gas adsorption-desorption tower 110, and a liquid outlet valve 122 is provided on the liquid outlet pipe 114 of each exhaust gas adsorption-desorption tower 110.

[0046] The VOCs waste gas adsorption and desorption treatment system provided by the present invention also includes a PLC automatic control device (not shown in the figure). The PLC automatic control device is electrically connected to each valve, bacterial liquid transfer pump 220, aeration fan 230, maintenance agent dosing pump 260, heater 310, drying fan 320 and waste gas fan 410, and is used to control their opening and closing.

[0047] According to the present invention, a method for treating VOCs waste gas by adsorption and desorption is also provided, which employs the VOCs waste gas adsorption and desorption treatment system described above, and includes the following steps: First, the adsorption mode is entered. One or more first inlet valves 117 of the waste gas adsorption-desorption tower 110 are opened, and the VOCs waste gas to be treated is introduced into the waste gas adsorption-desorption tower 110 through the main first inlet pipe 111a. After the waste gas is adsorbed by the solid adsorbent in the waste gas adsorption-desorption tower 110, the organic matter is adsorbed into the solid adsorbent. Then, the first outlet valve 119 of the waste gas adsorption-desorption tower 110 is opened, and the exhaust device 400 is started. The waste gas after adsorption treatment is discharged from the first outlet pipe 112 on the waste gas adsorption-desorption tower 110 and discharged to the atmosphere through the exhaust device 400. The exhaust fan 410 of the exhaust device 400 is a negative pressure controlled exhaust device to ensure that the waste gas adsorption-desorption tower 110 is in a negative pressure state of -100Pa to -500Pa throughout the entire waste gas treatment process, and no waste gas will enter the environment. The treated waste gas is discharged to the atmosphere through the exhaust stack 420. After one or more of the exhaust gas adsorption-desorption towers are saturated with adsorption, they enter the desorption mode. In the desorption mode, the first inlet valve 117, the first outlet valve 119, and the exhaust device 400 of the exhaust gas adsorption-desorption tower 110 to be desorbed are closed. The liquid inlet valve 121 of the exhaust gas adsorption-desorption tower 110 is opened, and the bacterial liquid transfer pump 220 is started to input the microbial liquid in the bacterial liquid tank 210 into the exhaust gas adsorption-desorption tower 110 until the microbial liquid covers the entire solid adsorbent. Then, the liquid inlet valve 121 and the bacterial liquid transfer pump 220 of the exhaust gas adsorption-desorption tower 110 are closed. Without any human intervention or the addition of chemical agents, the microbial liquid decomposes the organic matter adsorbed in the solid adsorbent into carbon dioxide and water, allowing the solid adsorbent to regain its adsorption capacity. The entire decomposition and desorption time is 60-84 hours. Throughout the decomposition and desorption process, the aeration blower 230 is kept running continuously to provide sufficient oxygen to the microbial liquid in the bacterial liquid tank 210 for decomposing organic matter, and the dissolved oxygen content in the bacterial liquid tank 210 is maintained at 2-6 mg / L; at the same time, nutrients are added to the bacterial liquid tank 210 in a timely and quantitative manner through the maintenance agent dosing pump 260 to maintain the microbial activity of the microbial liquid in the bacterial liquid tank 210 at the optimal state, and water is automatically replenished through the tap water pipe 270 to maintain the liquid level of the bacterial liquid tank 210; After desorption is completed, open the liquid outlet valve 122 of the waste gas desorption tower 110 to drain all the microbial liquid in the waste gas desorption tower 110 and return it to the liquid tank 210. Then, the drying mode is entered. The second air inlet valve 118 of the waste gas adsorption-desorption tower 110 is opened, and the heater 310 and drying fan 320 of the drying device 300 are started to send hot air at 40-80°C into the waste gas adsorption-desorption tower 110 to dry the moisture in the solid adsorbent in the waste gas adsorption-desorption tower 110, so that the solid adsorbent is kept in a dry state. After drying, the heater 310 is turned off, and the drying fan 320 continues to run. After the temperature of the solid adsorbent drops below 40°C, the drying fan 320 stops running. The waste gas adsorption-desorption tower 110 completes desorption and regeneration and enters the adsorption ready mode, which can be put into adsorption use at any time. Finally, open the second outlet valve 120 of the waste gas adsorption-desorption tower 110 and start the exhaust device 400 to discharge the dried gas in the waste gas adsorption-desorption tower 110 to the exhaust device 400 and out into the atmosphere.

[0048] In the VOCs waste gas adsorption and desorption treatment method provided by the present invention, the waste gas adsorption and desorption device 100 is provided with multiple waste gas adsorption and desorption towers 110. The specific number can be determined according to the waste gas volume and concentration. The number is usually 2-5 towers, and the waste gas treatment capacity of a single tower generally does not exceed 60,000 cubic meters / hour.

[0049] In the VOCs waste gas adsorption-desorption treatment method provided by this invention, after the waste gas adsorption-desorption tower is saturated with adsorption, it enters the desorption mode. In the desorption mode, the liquid-to-gas ratio of the bacterial solution to the waste gas is controlled at 0.001-0.005 m³ / s. 3 bacterial solution / m 3 At this liquid-to-gas ratio, the microbial liquid can achieve the most efficient adsorption and desorption process for the solid adsorbent in the waste gas adsorption-desorption tower while minimizing liquid consumption.

[0050] In the VOCs waste gas adsorption and desorption treatment method provided by the present invention, since the present invention uses specific microbial strains, a tower can simultaneously have the functions of adsorption and desorption. By controlling the opening and closing of each valve through a PLC automatic control device, the adsorption mode, desorption mode and drying mode of the waste gas adsorption and desorption tower 110 can be switched.

[0051] Taking the setting of three waste gas adsorption-desorption towers 110 as an example, each valve of each waste gas adsorption-desorption tower 110 is switched and controlled by a PLC automatic control device. The three waste gas adsorption-desorption towers 110 are named Tower A, Tower B, and Tower C, and are periodically switched between adsorption mode, desorption mode, and drying mode as shown in Table 1. The switching cycle is related to the VOCs concentration in the waste gas being treated, and each cycle is normally controlled within 1-3 days.

[0052] Table 1

[0053] The VOCs waste gas adsorption-desorption treatment system and method provided by this invention employs *Bacillus baileyi* (a type of bacteria) obtained through separation, purification, and screening of sediment from spray paint wastewater. Beijerinckia sp. LM-W, accession number: CGMCC No. 17168) and / or Bacillus brevis ( Brachymonas sp. The regenerated bacterial solution, composed of LM-R (accession number: CGMCC No. 17167), enters the waste gas adsorption-desorption tower. It efficiently decomposes the organic matter adsorbed by the solid adsorbent. Without any manual intervention or chemical additives, the microorganisms can automatically decompose and desorb the organic matter in the saturated solid adsorbent. The entire desorption and desorption process takes only 60-84 hours, allowing for simultaneous adsorption and desorption within a single tower. This eliminates the need for additional energy-intensive desorption devices such as high-temperature combustion or hot steam, significantly reducing the cost of the waste gas treatment system and greatly simplifying the process. The microbial solution directly decomposes the organic matter in the solid adsorbent, avoiding the formation of high-concentration waste gas like existing high-temperature combustion or hot steam desorption devices, thus greatly reducing the operational and maintenance risks of the treatment system. The microorganisms used are non-toxic and harmless, decomposing the organic matter in the waste gas into non-toxic and harmless carbon dioxide and water, making the entire waste gas treatment process more environmentally friendly and preventing the generation of secondary harmful substances.

[0054] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A VOCs waste gas adsorption-desorption treatment system, characterized in that, It includes a waste gas adsorption and desorption device, a bacterial growth device, a drying device, and an exhaust system; among which, The waste gas adsorption-desorption device includes at least two waste gas adsorption-desorption towers connected in series or in parallel. The waste gas adsorption-desorption towers are filled with solid adsorbent. Each waste gas adsorption-desorption tower is provided with a first inlet pipe and a first outlet pipe. The first inlet pipes of each waste gas adsorption-desorption tower are connected and converged into a total first inlet pipe. VOCs waste gas is introduced from the total first inlet pipe. The first outlet pipe of the waste gas adsorption-desorption tower is connected to the inlet of the exhaust device. The outlet of the exhaust device is connected to the atmosphere. The bacterial liquid growth device includes a bacterial liquid tank containing microbial bacterial liquid. Each waste gas adsorption-desorption tower is provided with an inlet pipe and an outlet pipe, which are respectively connected to the bacterial liquid tank. Each waste gas adsorption-desorption tower is equipped with a second inlet pipe and a second outlet pipe. The second inlet pipe of the waste gas adsorption-desorption tower is connected to the outlet of the drying device and is used to dry the solid adsorbent in the waste gas adsorption-desorption tower. The second outlet pipe of the waste gas adsorption-desorption tower is connected to the inlet of the exhaust device and is used to discharge the dried gas to the exhaust device.

2. The VOCs waste gas adsorption-desorption treatment system according to claim 1, characterized in that, The solid adsorbent is selected from one or more of activated carbon, zeolite molecular sieves and resins, and the microbial inoculum is an agronomic microbial inoculum.

3. The VOCs waste gas adsorption-desorption treatment system according to claim 1, characterized in that, Each waste gas adsorption-desorption tower body has a first inlet valve on its first inlet pipe, a second inlet valve on its second inlet pipe, a first outlet valve on its first outlet pipe, a second outlet valve on its second outlet pipe, a liquid inlet valve on its liquid inlet pipe, and a liquid outlet valve on its liquid outlet pipe.

4. The VOCs waste gas adsorption-desorption treatment system according to claim 1, characterized in that, The first and second inlet pipes of each waste gas adsorption-desorption tower are located at the bottom of the tower, the first and second outlet pipes of each tower are located at the top, the liquid inlet pipe of each tower is located at the top, and the liquid outlet pipe of each tower is located at the bottom.

5. The VOCs waste gas adsorption-desorption treatment system according to claim 1 or 4, characterized in that, The bacterial liquid growth device also includes a bacterial liquid delivery pump, an aeration blower, an aeration duct, a dosing pipe, a maintenance agent dosing pump, and a tap water pipe. The bacterial liquid delivery pump is located on the path of the main inlet pipe formed by the inlet pipes of each waste gas adsorption-desorption tower. The aeration blower is located outside the bacterial liquid tank and connected to one end of the aeration duct. The other end of the aeration duct enters the bacterial liquid tank from the bottom. The dosing pipe and the tap water pipe both enter the bacterial liquid tank from the top. The maintenance agent dosing pump is located on the path of the dosing pipe.

6. The VOCs waste gas adsorption-desorption treatment system according to claim 1 or 4, characterized in that, The drying device includes a heater and a drying fan. The heater is an air heater or an electric heater. The drying fan is connected to the inlet of the heater. The second air inlet pipes on each of the exhaust gas adsorption-desorption towers are connected to form a total second air inlet pipe, which is connected to the outlet of the heater.

7. The VOCs waste gas adsorption-desorption treatment system according to claim 1 or 4, characterized in that, The exhaust system includes an exhaust fan and an exhaust stack. The first exhaust pipes on each exhaust gas adsorption-desorption tower are connected and converged into a main exhaust pipe. The second exhaust pipes on each exhaust gas adsorption-desorption tower are connected and converged into the main exhaust pipe. The main exhaust pipe is connected to the inlet of the exhaust fan, the outlet of the exhaust fan is connected to the inlet of the exhaust stack, and the outlet of the exhaust stack is connected to the atmosphere. The exhaust fan is a negative pressure control exhaust device used to control the exhaust gas adsorption-desorption tower to be in a negative pressure state throughout the entire exhaust gas treatment process.

8. The VOCs waste gas adsorption-desorption treatment system according to any one of claims 1-7, characterized in that, It also includes a PLC automatic control device, which is electrically connected to various valves, bacterial liquid transfer pumps, aeration fans, maintenance agent dosing pumps, heaters, drying fans and exhaust fans, and is used to control their opening and closing.

9. A method for treating VOCs waste gas by adsorption and desorption, characterized in that, The VOCs exhaust gas adsorption and desorption treatment system as described in any one of claims 1-8 includes the following steps: (1) First, enter the adsorption mode, open the first inlet valve of one or more waste gas adsorption and desorption towers, and introduce the VOCs waste gas to be treated into the waste gas adsorption and desorption tower through the main first inlet pipe. After the waste gas is adsorbed by the solid adsorbent in the waste gas adsorption and desorption tower, the organic matter is adsorbed into the solid adsorbent. Then, open the first outlet valve of the waste gas adsorption and desorption tower, start the exhaust device, and the waste gas after adsorption treatment is discharged from the first outlet pipe on the waste gas adsorption and desorption tower and discharged into the atmosphere through the exhaust device. (2) After one or more waste gas adsorption-desorption towers are saturated with adsorption, the desorption mode is entered. Microbial liquid from the bacterial liquid tank is introduced into the waste gas adsorption-desorption tower until the microbial liquid covers the entire solid adsorbent. Without any manual intervention or addition of chemical agents, the microbial liquid decomposes the organic matter adsorbed in the solid adsorbent into carbon dioxide and water, so that the solid adsorbent regains its adsorption capacity. The microbial liquid consists of sterile water and microbial strains. The microbial strains are obtained by separating, purifying and screening *Bacillus baileyi* (LM-W, accession number: CGMCC No. 17168) and *Bacillus brevis* (LM-R, accession number: CGMCC) from the bottom sludge of spray paint wastewater. Composition No. 17167); In the regenerated bacterial solution, the bacterial concentration of *Bacillus baileyi* is 5-50 million CFU / ml, the bacterial concentration of *Bacillus brevis* is 5-50 million CFU / ml, and the colony count ratio of *Bacillus baileyi* to *Bacillus brevis* is 1:(1-5). (3) After desorption is completed, open the liquid outlet valve of the waste gas desorption tower body so that all the microbial liquid in the waste gas desorption tower body is discharged and returned to the liquid tank; (4) Then enter the drying mode to dry the moisture in the solid adsorbent in the waste gas adsorption-desorption tower, so that the solid adsorbent is kept dry. The waste gas adsorption-desorption tower completes desorption and regeneration and enters the adsorption ready mode, which can be put into adsorption at any time. (5) The dried gas in the exhaust gas desorption tower is discharged to the exhaust device and discharged into the atmosphere.

10. The VOCs waste gas adsorption-desorption treatment method according to claim 9, characterized in that, Three or more waste gas adsorption-desorption towers are set up, and the opening and closing of each valve is controlled by a PLC automatic control device to switch between adsorption mode, desorption mode and drying mode for the three or more waste gas adsorption-desorption towers.

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