Method for quickly starting biological filter bed based on fungus-bacterium coordinated regulation and control

Abstract

The invention relates to a quick starting method of a biological filter bed based on fungus-bacterium coordinated regulation. The quick starting method adopts a two-step method and comprises the following steps: firstly, quickly starting a bacterium filter bed by taking benzyl alcohol as a carbon source; adjusting the pH value to 5.5-6.2, adding wheat bran, and implementing intermittent hypoxia stimulation (replacing antibiotics) until the absolute copy number ratio of fungi / bacteria is (F / B) gt; and the starting is finished when the temperature is 0.35. The whole process is free of antibiotics, the starting period is smaller than or equal to 14 days, the methylbenzene removal rate is larger than or equal to 95%, the mineralization rate is larger than or equal to 80%, and the method is remarkably superior to the prior art and suitable for large-air-volume and low-concentration hydrophobic VOCs treatment.

Description

Technical Field

[0001] This invention relates to the field of air pollution control technology, and in particular to a rapid start-up method for a biofilter based on fungal-bacterial synergistic regulation, especially a method for constructing and rapidly starting up a fungal-bacterial hybrid biofilter for treating volatile organic compounds (VOCs). Background Technology

[0002] Biofiltration technology is an effective method for treating large volumes of low-concentration VOCs in waste gas. For hydrophobic VOCs (such as toluene), fungal-bacterial hybrid biofilters show superior performance compared to single-strain filters because they combine the strong gas-phase adsorption capacity of fungi with the efficient and diverse degradation capabilities of bacteria.

[0003] Currently, the conventional method for constructing such hybrid filter beds is to inhibit bacterial growth and promote fungal growth by adjusting the pH and adding antibiotics, based on a bacterial filter bed. For example, existing technologies (Zhai et al., 2020) use 20 g / m³... 3 Chloramphenicol inhibits bacteria, achieving an F / B ratio > 0.27, but inevitably it also inhibits bacteria that play a key role in degradation within the system (such as...). Thauera The antibiotic residues caused indiscriminate inhibition, resulting in a 20%-30% decrease in its activity (based on the microbial sequencing data of Example 1 of this invention), ultimately resulting in a low system mineralization rate (the highest being only 77.6%). In addition, antibiotic residues also led to a 15%-20% increase in the COD of the nutrient solution, increasing subsequent treatment costs and environmental risks.

[0004] More importantly, in the specific technical field of gas-phase VOCs biofilter construction, there exists a long-standing technical bias: the widespread belief that "antibiotics are the only effective means to efficiently and rapidly inhibit bacteria in already colonized bacterial filters, thereby promoting fungal growth and achieving the construction of fungal-bacterial hybrid biofilters" (see Xiao-Xiao, Shi, Hai-Ping, Qiu, Jiao-Yu, & Wang, et al. (2019). A handy method to remove bacterial contamination from fungal cultures. PloS one, 14(11), e0224635. This literature review clearly states that "the use of antibiotics is a common strategy to control bacterial growth in fungal bioreactors"). Although there are reports of hypoxia regulation in liquid / solid phase systems such as wastewater or compost, its application in the specific field of gas-phase VOCs biofilters, using physical hypoxia stimulation to replace chemical antibiotics to precisely regulate the microbial community structure and thus achieve the rapid construction of high-performance hybrid filters, is neither publicly disclosed nor technically inspired in the existing technology. The applicant argues that those skilled in the art, concerned about the disruption of existing bacterial communities in the filter bed and the collapse of system performance, lack the motivation to attempt to use low-oxygen, a "high-risk" approach, as an alternative to the "mature" antibiotic regimen. This technological bias severely hinders the development of antibiotic-free, high-performance fungal-bacterial hybrid biofilters.

[0005] Therefore, there is an urgent need in this field to develop a method for constructing fungal-bacterial hybrid biofilters that can avoid the use of antibiotics while achieving faster start-up speed and higher degradation efficiency. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies, such as antibiotic dependence leading to microbial imbalance, suppressed activity of functional bacteria, long start-up period, and secondary pollution, and to provide a rapid start-up method for a biofilter based on fungal-bacterial synergistic regulation. Specifically, it is a method for constructing and rapidly starting up a fungal-bacterial hybrid biofilter for treating volatile organic compounds.

[0007] This invention unexpectedly discovered that, by implementing intermittent hypoxic stimulation under specific conditions, it is possible to inhibit the degradation of key functional bacteria (such as...). ThaueraUnder the premise of significant inhibition by fungi (with an activity retention rate ≥95%), selective regulation of the microbial community structure is achieved, thereby creating a competitive advantage for fungi. This approach successfully replaces chemical antibiotics with physical regulation, overcomes the aforementioned technical biases, and provides a brand-new technical route for the rapid, efficient, and environmentally friendly start-up of fungal-bacterial hybrid biofilters.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a rapid start-up method for a biofilter bed based on fungal-bacterial synergistic regulation, comprising the following steps: S1. Start-up stage of bacterial filter bed: Inoculate activated sludge into the filter bed, add the first exogenous carbon source to the nutrient solution, and pass toluene gas to complete the rapid biofilm formation and acclimatization of the bacterial filter bed in a toluene environment. S2. Construction stage of fungal-bacterial hybrid biofilter: After the bacterial filter is running stably, adjust the pH of the nutrient solution to a slightly acidic environment of 5.5-6.2, add a second exogenous carbon source, and implement intermittent low-oxygen stimulation as a key step; when the absolute copy number ratio of fungi / bacteria in the reactor (F / B) > 0.35, the construction and start-up are complete. The intermittent hypoxia stimulation refers to the periodic reduction of the oxygen volume concentration in the filter bed to 5%-10%, once every 5-8 hours, each time lasting 0.5-3 hours.

[0009] Intermittent hypoxia stimulation is administered 1-4 times daily, preferably 3-4 times. Preferably, the hypoxia is reduced every 5-7 hours, with each episode lasting 0.5-1.5 hours, more preferably 1 hour.

[0010] This invention utilizes low-oxygen stimulation technology to regulate the ratio of fungi and bacteria in the biofilm of the filter bed, thereby activating a fungal-bacterial mixed biofilter bed.

[0011] In one embodiment of the present invention, in step S1, the filter bed filler is polyurethane foam, preferably cubic (side length 4-6 mm) as filler.

[0012] In one embodiment of the present invention, in step S1, the inoculation concentration of the activated sludge is 2000-3000 mg VSS / L. The activated sludge is activated sludge from the wastewater treatment plant of an enterprise where industrial VOCs are located, and is used as the inoculation strain for the fungal-bacterial hybrid biofilter.

[0013] In one embodiment of the present invention, in step S1, the nutrient solution is sprayed once every 2-3 days, each time for 15-20 minutes, with a spraying volume of 20-40 mL·min. -1 .

[0014] In one embodiment of the present invention, in step S1, the nutrient solution is composed as follows: 4-5g KH2PO4, 0.4-0.6g K2HPO4, 1.8-2.2g NH4Cl, 0.8-1.2g MgCl2·6H2O, 1.5-2.5 mL vitamin solution, and 1.5-2.5 mL trace element solution are added per liter of water.

[0015] The preferred composition of the nutrient solution is: 4.5 g KH2PO4, 0.5 g K2HPO4, 2.0 g NH4Cl, 0.1 g MgCl2·6H2O, 2 mL vitamin solution, and 2 mL trace element solution per liter of water.

[0016] In one embodiment of the present invention, in step S1, the first exogenous carbon source is one or more of benzyl alcohol, ethanol, and glucose, and its concentration is 200-400 mg / m³. 3 The first exogenous carbon source was selected from carbon sources that are easily utilized by bacteria.

[0017] In one embodiment of the present invention, in step S1, the toluene inlet gas concentration gradually increases in three stages, with an initial concentration of 250-350 mg / m³. 3 When the toluene removal rate is >80%, the toluene inlet concentration increases to 450-550 mg / m³. 3 When the toluene removal rate is >80%, the toluene inlet concentration increases to 900-1100 mg / m³. 3 When the toluene removal rate is >80%, the rapid biofilm formation and acclimatization of the bacterial filter bed are considered complete. The empty bed residence time is 40-50 s, preferably 45 s. The toluene inlet concentration for the three stages is preferably 300 mg / m³. 3 500 mg / m 3 1000 mg / m 3 . In one embodiment of the present invention, in step S2, the pH of the nutrient solution is adjusted by using hydrochloric acid (0.1 mol / L).

[0018] In one embodiment of the present invention, in step S2, the second exogenous carbon source is one or more of wheat bran, starch, and lignocellulose, and its concentration is 80-150 mg / m³. 3 The second exogenous carbon source provides a dominant carbon source for fungi.

[0019] In one embodiment of the present invention, in step S2, the reduction of the oxygen volume concentration in the reactor is achieved by introducing nitrogen gas. By periodically reducing the oxygen concentration in the system (to 5%-10%), an environment favorable to fungal growth and unfavorable to competition from most aerobic bacteria is created, thereby rapidly increasing fungal biomass and F / B ratio.

[0020] The "fungal / bacterial absolute copy number ratio (F / B)" mentioned in this article refers to the ratio of the absolute copy number of fungal ribosomal DNA (such as the ITS region) to that of bacterial ribosomal DNA (such as the 16S rRNA gene) in a sample, as determined by quantitative PCR (qPCR). Preferably, the sample is a mixed biofilm sample collected from the packing zone in the middle of a biofilter.

[0021] The present invention also provides an application of the aforementioned rapid start-up method for the biofilter bed in the treatment of industrial waste gas containing toluene.

[0022] The technical solution of this invention is designed to address the core deficiencies of existing technologies by achieving a precise match between "problem-solution-effect" through "targeted regulation." The "antibiotic-free process" is the cornerstone of this solution, while "intermittent hypoxic stimulation" is the core means of achieving this cornerstone. The specific logic is as follows: (1) Regarding the technical problem that "existing technologies use antibiotics to indiscriminately inhibit bacteria, resulting in a decrease in the activity of functional degrading bacteria and a low mineralization rate".

[0023] This invention uses "intermittent hypoxia stimulation" instead of antibiotics: fungi (such as...) Ascomycota Phylum species (e.g., *Phyllium*) exhibit significantly higher tolerance to hypoxic environments than aerobic bacteria (e.g., *Phyllium*). Proteobacteria By periodically reducing the oxygen concentration to 5%-10%, the excessive proliferation of non-target aerobic bacteria can be selectively inhibited (to prevent them from competing with fungi for carbon sources), but this does not inhibit functional degrading bacteria (such as toluene-degrading bacteria) attached to the surface of fungal hyphae. Thauera (Genus), because these bacteria can obtain a small amount of oxygen through the "oxygen transport channels" of fungal hyphae to maintain their degradation activity (microbial sequencing data from Example 1 of this application show that...). Thauera With an activity retention rate of ≥95%, the problem of "antibiotic-inhibiting functional bacteria" is finally solved, and the mineralization rate is increased to over 80%.

[0024] (2) Regarding the technical problem of “slow initiation of fungal growth in existing technologies (slow proliferation after bacterial inhibition by antibiotics)”.

[0025] This invention simultaneously adds wheat bran (exogenous carbon source II) and low-oxygen stimulation: wheat bran provides fungi with a dedicated carbon source (fungi have a stronger ability to decompose complex organic matter than bacteria), and the low-oxygen environment further eliminates bacterial competition. The two work synergistically to promote the rapid growth of fungal hyphae (the specific surface area of ​​hyphae is increased by 40% compared with the existing technology), so that the F / B ratio can quickly break through 0.35, and the start-up period is shortened from more than 15 days to 12-14 days.

[0026] (3) Regarding the technical problem of "existing technology antibiotic residues leading to high environmental risks and costs".

[0027] This invention eliminates the need for any antibiotics throughout the entire process, fundamentally eliminating the environmental risks and subsequent treatment costs associated with antibiotic residues. Furthermore, this invention preferably replaces the conventional magnesium sulfate source in the nutrient solution with magnesium chloride (concentration of 0.05-0.15 g / L). This substitution brings unexpected technical benefits: firstly, magnesium chloride avoids the slight inhibition of fungal mycelial growth by sulfate (experiments have shown that the fungal proliferation rate is approximately 15% higher in a magnesium chloride environment compared to a magnesium sulfate environment); secondly, because no antibiotics are used and magnesium chloride itself does not introduce additional chemical oxygen demand (COD), the COD value of the system's nutrient solution is significantly reduced, further minimizing environmental risks and operating costs.

[0028] Compared with the prior art, the present invention has the following beneficial effects: (1) Significantly improved start-up efficiency: The precise physical regulation of the bacterial community structure is achieved through hypoxia stimulation, avoiding the “indiscriminate attack” of antibiotics, and the start-up cycle is shortened from more than 15 days to 12-14 days.

[0029] (2) Enhanced pollutant purification performance: Due to the complete preservation of the degradation activity of functional bacteria, a highly efficient synergy is formed with the adsorption and transport capacity of fungi. The toluene removal rate is stable at over 95%, and the mineralization rate is increased to over 80%, achieving more thorough degradation.

[0030] (3) The system operates more stably: the non-chemical regulation method maintains the ecological balance of the microbial community, avoids the destruction of biofilm structure caused by the death of a large number of bacteria, and the system pressure drop is stabilized at a low level of about 5.0 cm H2O / m, which is conducive to long-term operation.

[0031] (4) It is environmentally friendly and economical: It eliminates the use of antibiotics, thus fundamentally eliminating the environmental risks and additional treatment costs they bring. Attached Figure Description

[0032] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a comparison chart of the startup performance of Embodiment 1 and Comparative Example 1 of the present invention; Figure 2 This is a comparison graph showing the change in the absolute copy number ratio (F / B) of fungi / bacteria during the operation of the method of the present invention and Comparative Example 1; Figure 3 This is a bar chart comparing the toluene mineralization rate of the method of the present invention and Comparative Example 1 during the stable operation phase. Figure 4 This is a comparison diagram of the microbial community structure between the method of the present invention and Comparative Example 1; Figure 5 This is a schematic diagram of the system structure and hypoxia stimulation control of the present invention. Detailed Implementation

[0033] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The following examples are implemented under the premise of the technical solution of the present invention, providing detailed implementation methods and specific operating procedures, which will help those skilled in the art to further understand the present invention. It should be noted that the scope of protection of the present invention is not limited to the following embodiments; any adjustments and improvements made under the concept of the present invention are all within the scope of protection of the present invention.

[0034] This invention is a rapid start-up method for a biofilter based on fungal-bacterial synergistic regulation. It employs a two-step approach, the core of which is the complete absence of antibiotics. Instead of chemical antibiotics, the method uses intermittent physical hypoxia stimulation to regulate the microbial community structure. A schematic diagram of the system structure and hypoxia stimulation control is shown below. Figure 5 As shown, it specifically includes: (1) Start-up stage of bacterial filter bed: Inoculate activated sludge into the filter bed and add the first exogenous carbon source to the nutrient solution at the same time. Complete the rapid biofilm formation and acclimatization of the bacterial filter bed in the toluene waste gas environment.

[0035] (2) Construction stage of fungal-bacterial hybrid biofilter: After the bacterial filter is running stably, the pH of the nutrient solution is adjusted to a weakly acidic environment of 5.5-6.2, and a second exogenous carbon source is added. Intermittent hypoxia stimulation is then implemented as a key technique. By periodically reducing the oxygen concentration in the system (to 5%-10%), an environment favorable to fungal growth and unfavorable to competition from most aerobic bacteria is created, thereby rapidly increasing fungal biomass and the F / B ratio. When the absolute copy number ratio of fungi to bacteria (F / B) in the reactor is >0.35, the construction and startup are complete.

[0036] This invention achieves precise reconstruction of the microbial community structure through the synergistic effect of "intermittent hypoxia stimulation" and "wheat bran addition," along with the use of "magnesium chloride as a source." The effect is not simply the sum of these methods: while hypoxia stimulation inhibits non-target bacteria, it creates a "micro-aerobic niche" based on the fungal hyphal network, providing a sanctuary for the core functional degrading bacteria; meanwhile, wheat bran provides the fungi with a superior carbon source. This combination of "physical selective pressure and nutrient competition" creates a novel, dynamically balanced fungal-bacterial symbiotic system, which cannot be achieved by existing technologies relying on antibiotic "bactericidal" methods.

[0037] Example 1 Filter bed and packing material: An organic glass column with an inner diameter of 7 cm and a height of 60 cm is used, filled with polyurethane foam cubes (side length 4-6 mm) as packing material.

[0038] The method described in this invention particularly preferably uses magnesium chloride as the magnesium source of the nutrient solution to avoid the potential inhibition of fungal hyphae by sulfate and to reduce the system COD. The following examples all adopt this preferred approach.

[0039] Nutrient solution composition (per liter): 4.5 g KH2PO4, 0.5 g K2HPO4, 2.0 g NH4Cl, 0.1 g MgCl2·6H2O, 2 mL vitamin solution, 2 mL trace element solution.

[0040] Table 1. Composition of Vitamin Solution

[0041] Table 2 Composition of Trace Element Solution

[0042] Step (1) Start-up of the bacterial filter bed: Inoculate with 2500 mg VSS / L Yangzi Petrochemical activated sludge.

[0043] Add benzyl alcohol (TOC 300 mg / m³) 3 ) as an exogenous carbon source I.

[0044] Spray nutrient solution every 2 days, each time for 20 minutes, with a spray volume of 30 mL / min. -1 .

[0045] Toluene gas is continuously introduced, with the toluene concentration in the inlet gas increasing from 300 to 500 to 1000 mg / m³. 3 The process involves three stages of improvement. In each stage, when the toluene removal rate is >80%, the concentration is increased, and the empty bed residence time is 45 s.

[0046] On the 10th day, the toluene removal rate in the third stage reached 88%, indicating that the bacterial filter bed had been successfully started.

[0047] Step (2) Construction of fungal-bacterial hybrid biofilter: Adjust the pH of the nutrient solution to 5.9 using hydrochloric acid (0.1 mol / L).

[0048] Add wheat bran (TOC 100 mg / m³) 3 ) as an exogenous carbon source II.

[0049] Implement intermittent hypoxia stimulation (once every 6 hours): Maintain a constant total inlet flow rate of toluene exhaust gas, and switch part of the inlet gas to nitrogen through a three-way valve and mass flow controller, reducing the oxygen volume concentration in the mixed gas to 7±0.5%, while the toluene concentration is reduced proportionally. After the hypoxia stimulation ends, restore the toluene exhaust gas inlet gas to the normal ratio.

[0050] Nutrient solution spraying should be scheduled during the interval between two hypoxic stimuli to avoid short-term interference of the spray solution with the gas concentration distribution.

[0051] No antibiotics are added throughout the entire process.

[0052] Results: On day 12, qPCR analysis was performed on biofilm samples collected from the middle packing zone of the filter bed. The F / B ratio reached 0.38 and tended to stabilize. At this point, the toluene removal rate was 96.2%, the mineralization rate was 81.5%, and the system pressure dropped to 5.1 cm H2O / m.

[0053] This demonstrates that intermittent hypoxia stimulation, as a form of "selective stress," inhibits non-target aerobic bacteria while simultaneously promoting the growth of core functional bacteria (such as...). Thauera The fungus provides a "micro-oxygen sanctuary" (with an activity retention rate of ≥95%), ultimately achieving efficient synergy between fungal adsorption and bacterial degradation.

[0054] Comparative Example 1 Except for step (2), where hypoxia stimulation is omitted, instead, 20 g / m³ of oxygen is added to the nutrient solution. 3 Except for chloramphenicol, the other conditions were exactly the same as in Example 1.

[0055] Results: The F / B ratio only reached 0.28 on day 18. After stabilization, the toluene removal rate was 93.0%, and the mineralization rate was 77.6%. Microbial activity analysis of biofilm samples revealed that key toluene-degrading bacteria (such as...) Thauera The activity of the genus decreased by approximately 28% from the initial level. The system pressure drop was initially 5.8 cm H2O / m, but continued to rise to 6.5 cm H2O / m during long-term operation (after 20 days), indicating that the biofilm structure deteriorated due to the large-scale death of bacteria and there was a risk of blockage.

[0056] Comparative Example 2 (low oxygen concentration: <5%) Except for step (2), where the oxygen concentration for intermittent hypoxia stimulation is controlled at 3%, the other conditions are exactly the same as in Example 1.

[0057] Results: The system's performance continued to deteriorate. Until day 18, the F / B ratio remained at only 0.15, and the system failed to stabilize. Toluene removal rates fluctuated between 65% and 70%, with an average mineralization rate as low as approximately 60%. Microscopic observation of the biofilm revealed that fungal hyphae were almost unobservable, and the biofilm was extremely sparse and loosely structured. These results confirm that when the oxygen concentration falls below the critical value of 5%, the system cannot establish an effective fungal-bacterial synergistic degradation system. Instead, severe hypoxia impairs the metabolic function of the entire microbial community (including bacteria), leading to a systemic collapse in treatment performance.

[0058] Comparative Example 3 (Hypoxia stimulation cycle changed: total duration unchanged) Except for step (2), in which the period of intermittent hypoxia stimulation is adjusted to every 12 hours, nitrogen is mixed into the intake air for 2 hours to reduce the oxygen concentration in the reactor to 7±0.5%, the other conditions are exactly the same as in Example 1.

[0059] Results: The start-up period was extended to 16 days, with the F / B ratio only 0.32 on day 16. During the stable operation phase, the toluene removal rate was 94.5%, the mineralization rate was 79.8%, and the system pressure drop was 5.3 cm H2O / m. Although still superior to the antibiotic method in Comparative Example 1, it was significantly inferior to Example 1 (12-day start-up, F / B ratio of 0.38, mineralization rate of 81.5%). These results indicate that, under the same total hypoxia time (4 hours per day), although a reduced stimulation frequency (once every 12 hours) can still achieve an F / B ratio exceeding 0.35, its start-up speed and microbial community structure optimization efficiency are inferior to the higher-frequency stimulation scheme (once every 6 hours), suggesting that periodic, intermittent hypoxia patterns have a significant impact on maintaining the continuous competitive advantage of fungi.

[0060] Comparative Example 4 (Hypoxia stimulation cycle changed: total duration unchanged) Except for step (2), in which the period of intermittent hypoxia stimulation is adjusted to every 3 hours, nitrogen is mixed into the intake air for 0.5 hours to reduce the oxygen concentration in the reactor to 7±0.5%, the other conditions are exactly the same as in Example 1.

[0061] Results: Although successful startup was achieved within 14 days with an F / B ratio of 0.37, the toluene removal rate was only 94.0%, the mineralization rate slightly decreased to 79.5%, and the system pressure drop slightly increased (5.4 cmH2O / m³). The reasons for this were: excessively high stimulation frequency (once every 3 hours) affected the metabolic adaptability of the bacterial community; short-term, repeated hypoxic shocks inhibited the growth of some functional bacteria and increased operational control difficulty; while the short duration of each stimulation (0.5 hours) failed to fully exert the selective regulatory effect on bacteria. These results further illustrate that the "intermittent hypoxic stimulation" used in this invention requires a balance between stimulation frequency (less than 4 times per day) and single-stress duration (≥0.5 hours). While excessively frequent stimulation can still achieve the target F / B ratio, it is not optimal in terms of treatment efficiency and system stability, highlighting the comprehensive advantages of the preferred scheme of this invention (every 6 hours, for 1 hour) in terms of operational feasibility and functional synergy.

[0062] Comparative Example 5 (Magnesium Source Replacement: Magnesium Sulfate Instead of Magnesium Chloride) Except for replacing the magnesium source in the nutrient solution with magnesium chloride (MgCl2·6H2O) with magnesium sulfate (MgSO4·7H2O) of equal molar concentration, the other conditions were exactly the same as in Example 1.

[0063] Results: The system start-up period was extended to 14 days, with an F / B ratio of 0.36 on day 14. During the stable operation phase, the toluene removal rate was 95.5%, the mineralization rate was 78.9%, and the system pressure drop was 5.2 cmH2O / m³. Furthermore, monitoring the COD value of the nutrient solution revealed that the magnesium sulfate system had a COD value approximately 8% higher than the magnesium chloride system, and microscopic observation of the fungal hyphae showed that their biomass and hyphal density were slightly lower than in Example 1 (approximately 12% lower). The results indicate that although magnesium sulfate can still be used as a magnesium source to achieve system start-up, it is weaker than the magnesium chloride system in terms of fungal proliferation rate, degradation completeness (mineralization rate), and system chemical oxygen demand.

[0064] Example 2: Parameter Optimization Inoculate with 2000 mg VSS / L Nanjing Iron and Steel activated sludge.

[0065] Benzyl alcohol dosage concentration 200 mg / m 3 .

[0066] Adjust the pH to 6.0 and add wheat bran at a concentration of 80 mg / m³. 3 .

[0067] Hypoxia stimulation: twice daily (12-hour interval), 1.5 hours each time, until the oxygen concentration drops to 8%.

[0068] The remaining steps are the same as in Example 1.

[0069] Results: On day 14, the F / B ratio reached 0.36. After stabilization, the toluene removal rate was 95.1%, and the mineralization rate was 80.3%.

[0070] The startup performance comparison chart between Example 1 and Comparative Example 1 is shown below. Figure 1 As shown.

[0071] The following is a comparison of the changes in the absolute copy number ratio (F / B) of fungi / bacteria during the operation of Examples 1 and 2 and Comparative Example 1: Figure 2 As shown.

[0072] The bar chart comparing the toluene mineralization rates of Example 1 and Comparative Example 1 during the stable operation phase is shown below. Figure 3 As shown.

[0073] The microbial community structure comparison diagram between Example 1 and Comparative Example 1 is shown below. Figure 4 As shown.

[0074] The key data comparisons of the examples and comparative examples are shown in Table 3.

[0075] Table 3

[0076] The data from the examples show that fungal growth is inhibited when the hypoxia concentration is below 5%, while the regulatory effect on aerobic bacteria weakens and the start-up period is prolonged when the concentration is above 10%. In summary, controlling the hypoxia concentration between 5% and 10% achieves the objectives of this invention, but there are gradient differences in performance. 6-8% has been proven to be a "particularly preferred range," within which the fastest start-up speed (e.g., Example 1, 12 days) and the highest pollutant removal performance can be achieved simultaneously. Even at the upper limit of this range of 8% (Example 2, 14 days of start-up), the start-up efficiency is significantly better than the prior art (Comparative Example 1, 18 days). Therefore, the specific parameters of the intermittent hypoxia stimulation (especially the concentration range of 5%-10% and its performance gradient) are not conventional choices for those skilled in the art, nor are they found in the prior art.

[0077] The data from the above embodiments fully demonstrate that the present invention, through the technical route of "antibiotic-free + intermittent hypoxia stimulation", is significantly superior to the prior art in terms of start-up speed, precision of microbial community structure regulation, and final purification performance.

[0078] To quantitatively evaluate the regulatory advantages of the core method of this invention—intermittent hypoxia stimulation—compared to the prior art (antibiotic method), microbial activity analysis was performed on biofilm samples from the stable operation phase of Example 1 and Comparative Example 1.

[0079] The results showed that under the preferred hypoxic stimulation conditions described in this invention (i.e., once every 6 hours of operation, each lasting 1 hour, with the oxygen concentration reduced to 7±0.5%), the proliferation rate of fungal hyphae was increased by more than 30% compared to Comparative Example 1 (antibiotic method); simultaneously, analysis of the functional flora using high-throughput sequencing and quantitative PCR revealed that the key toluene-degrading bacteria ( Thauera The activity retention rate of the genus is as high as 95% or more.

[0080] This set of comparative data fully demonstrates that the intermittent hypoxia stimulation of the present invention can effectively maintain the degradation activity of functional bacteria while rapidly promoting fungal colonization, thereby achieving precise and healthy regulation of the bacterial community structure. This is the fundamental reason why its performance is comprehensively superior to that of the antibiotic method.

[0081] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method for rapid start-up of a fungus-bacteria synergistically regulated biofilter bed, characterized by, The method comprises the following steps: S1, bacterial filter bed starting stage: inoculating activated sludge in the biological filter bed, adding a first exogenous carbon source in the nutrient solution, passing toluene gas, and completing the rapid biofilm formation and domestication of the bacterial filter bed in the toluene environment; S2, fungus-bacteria mixed biological filter bed construction stage: after the bacterial filter bed is stably operated, the pH value of the nutrient solution is adjusted to a weak acidic environment of 5.5-6.2, a second exogenous carbon source is added, and intermittent low oxygen stimulation is implemented; when the absolute copy number ratio of fungi / bacteria in the reactor is >0.35, the start of the biological filter bed is completed; The intermittent low oxygen stimulation refers to periodically reducing the oxygen volume concentration in the biological filter bed to 5%-10%, reducing once every 5-8 hours, and lasting for 0.5-3 hours each time.

2. The rapid start-up of a biological filter bed of claim 1, wherein, In step S1, the filler of the biological filter bed is polyurethane foam.

3. The rapid start-up of a biological filter bed of claim 1, wherein, In step S1, the inoculation concentration of the activated sludge is 2000-3000 mg VSS / L.

4. The rapid start-up of a biological filter bed of claim 1, wherein, In step S1, the nutrient solution is sprayed once every 2-3 days, for 15-20 min each time, at a spraying amount of 20-40 mL min -1 .

5. The rapid start-up of a biological filter bed of claim 1 wherein, In step S1, the composition of the nutrient solution is as follows: adding 4-5 g of KH2PO4, 0.4-0.6 g of K2HPO4, 1.8-2.2 g of NH4Cl, 0.8-1.2 g of MgCl2·6H2O, 1.5-2.5 mL of a vitamin solution, and 1.5-2.5 mL of a trace element solution in each liter of water.

6. The rapid start-up of a biological filter bed of claim 1 wherein, In step S1, the first exogenous carbon source is one or more of benzyl alcohol, ethanol, and glucose; and / or, the first exogenous carbon source is added at a concentration of 200-400 mg / m 3 .

7. The rapid start-up of a biological filter bed of claim 1 wherein, In step S1, the toluene inlet concentration is gradually increased in three stages: the initial concentration is 250-350 mg / m 3 When the toluene removal rate is > 80%, the toluene inlet concentration is increased to 450-550 mg / m 3 When the toluene removal rate is > 80%, the toluene inlet concentration is increased to 900-1100 mg / m 3 When the toluene removal rate is > 80%, it is determined that the rapid biofilm formation and acclimation of the bacterial filter bed are completed.

8. The rapid start-up of a biological filter bed of claim 1 wherein, In step S2, the second exogenous carbon source is one or more of wheat bran, starch, and lignocellulose; and / or, the second exogenous carbon source is dosed at a concentration of 80-150 mg / m 3 .

9. The rapid start-up of a biological filter bed of claim 1 wherein, In step S2, the oxygen volume concentration in the reactor is reduced by passing nitrogen.

10. Application of the rapid start of the biological filter bed according to any one of claims 1-9 in treating industrial waste gas containing toluene.

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