A method for suppressing odor emissions during the storage of feces using fermentation acidification liquid.

Abstract

This invention provides a method for suppressing odor emissions during manure storage using fermentation acidification liquid. Specifically, anaerobic fermentation acidification liquid is added during manure storage, with a total acid concentration of 30-120 mmol / L. The addition frequency is once every 12-48 hours, and the application rate is 2-8 mL / kg. This method can reduce ammonia (NH3) emissions by 31.0%-47.0% and hydrogen sulfide (H2S) emissions by 35.2%-96.7% during manure storage. This method significantly reduces nutrient loss during livestock and poultry manure storage, has a significant deodorizing effect, is highly operable, and has the potential for large-scale production.

Description

Technical Field

[0001] This invention relates to the fields of organic waste storage management, resource recycling, and ecological environment, and in particular to a method for suppressing odor emissions during the storage of fecal waste using fermentation acidification liquid. Background Technology

[0002] During the management of livestock manure, the continuous decomposition of organic matter by microorganisms in the manure produces a large amount of foul-smelling gases (hereinafter referred to as "odors"), which are released into the air, seriously affecting human and animal health and environmental quality, leading to many public health problems. Meanwhile, manure storage is a key step before the harmless treatment of livestock manure, such as aerobic composting or anaerobic fermentation. Storage time is generally 1–30 days, making it a hotspot for odor generation.

[0003] The odorous gases released during the storage of feces and sewage mainly consist of two categories: nitrogen-containing and sulfur-containing gases. Nitrogen-containing odorous gases primarily include ammonia (NH3) and nitrogen-containing organic matter. NH3, in particular, has a pungent odor (odor threshold 0.027 mg / m³). 3 Sulfur-containing odorous gases account for approximately 47% to 77% of the total nitrogen loss during the storage process, making them one of the most significant odor-causing substances and the primary pathway for nitrogen loss. These gases are mainly volatile sulfides, including volatile inorganic sulfides such as hydrogen sulfide (H2S) and carbon disulfide (CS2), and volatile organic sulfides such as methanethiol (MT), dimethyl sulfide (DMS), and dimethyl disulfide (DMDS). H2S is the most abundant volatile sulfide produced during sewage storage, accounting for 39% to 43% of the total sulfur release, but its odor threshold (0.47 × 10⁻⁶) is relatively low. -3 mg / m 3 The concentration of H2S is low, therefore even low concentrations of H2S can produce a strong odor. In summary, the synergistic reduction of NH3 and H2S emissions during the storage of organic waste is the core of effectively controlling odor emissions.

[0004] NH3, as an alkaline gas, is extremely sensitive to acidity and alkalinity. A meta-analysis of extensive literature data by Cao et al. (Cao YB, Wang X, Bai ZH, Chadwick D, Misselbrook T, Sommer SG, Qin W, Ma L. Mitigation of ammonia, nitrous oxide and methane emissions during solid waste composting with different additives: Ameta-analysis[J]. Journal of Cleaner Production, 2019, 235: 626-635) showed that acidic additives significantly reduced NH3 emissions better than other additives, and this is currently a common and effective treatment technology for reducing nitrogen loss. The generation of H2S is closely related to organic sulfur conversion and sulfate reduction pathways. On the one hand, proteases and peptidases secreted by microorganisms can decompose sulfur-containing organic matter into sulfur-containing amino acids, which are then degraded by microorganisms such as *Pseudomonas putida* into MT, DMS, and DMDS. MT and DMS can generate H2S through degradation. On the other hand, during the storage of organic waste, localized hypoxic or anaerobic environments easily form inside the pile, which is conducive to the growth of sulfate-reducing bacteria. These microorganisms are key microorganisms that utilize sulfate as an electron acceptor to metabolize sulfur. Sulfate is first reduced to sulfite, then to thiosulfate and sulfides, and finally to H2S. However, through the action of sulfur-oxidizing microorganisms, sulfides can be converted into sulfate or elemental sulfur, inhibiting the release of H2S into the air. Therefore, reducing the activity of *Pseudomonas putida* or increasing the activity of sulfur-oxidizing microorganisms is an important way to effectively inhibit the generation and emission of H2S. However, to date, there are few reports on the synergistic reduction of NH3 and H2S emissions during the treatment of sewage.

[0005] Studies have found that appropriate initial C / N ratio conditions, moisture conditions, and forced aeration—endogenous parameters for composting—can reduce NH3 and H2S emissions during the composting process. However, these operations are difficult to implement in the temporary storage of manure, and the parameters often conflict. Therefore, acidic additives are the most important strategy for achieving synergistic reduction of NH3 and H2S emissions during the temporary storage of manure. Commonly used acidic additives include acidic salts and inorganic acids, but they are costly to process, cause serious secondary pollution, and pose safety hazards (such as sulfuric acid, phosphoric acid, and hydrochloric acid). Organic acids such as oxalic acid, citric acid, and lactic acid possess certain acidity, safety, and environmental friendliness. In recent years, some scholars have applied them in the process of reducing NH3 emissions during manure storage (Liu Juan, Bai Zhaohai, Cao Yubo, Zhang Nannan, Zhao Zhanqing, Ma Lin. The effect of surface acidification of manure in livestock pens on ammonia emissions. Chinese Journal of Eco-Agriculture (Chinese and English), 2019, 27(5):677-685); Liu Juan, Wang Xuan, Cao Yubo, Bai Zhaohai, Ma Lin. Research and application of ammonia emission reduction technology for manure acidification in livestock pens [J]. Chinese Journal of Eco-Agriculture (Chinese and English), 2023, 31(2):290-299). However, the methods currently reported often involve large amounts of commonly used organic acids, and the synergistic emission reduction effect of NH3 and H2S is not obvious. The prices are generally high, increasing the treatment cost. Therefore, exploring new organic acids that are low-cost and effective in reducing odor emissions during manure storage has become an urgent technical problem to be solved in this field. Currently, there are no reports on research into using fermentation acidification liquid to suppress the generation and emission of odorous gases such as NH3 and H2S. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a method for suppressing odor generation during the storage of organic waste using fermentation acidification liquid, thereby synergistically reducing the emissions of NH3 and H2S, mitigating the serious impact of odor on human and animal health and environmental quality, and improving resource utilization efficiency.

[0007] Specifically, the above-mentioned objective is achieved through the following technical solutions:

[0008] First, this application provides a method for suppressing odor generation during the storage of organic waste using fermentation acidification liquid, comprising the following steps:

[0009] 1) Crush organic waste to about 2cm and use it as fermentation raw material;

[0010] The aforementioned organic waste includes at least one of acidic materials such as straw, vegetable waste, and distiller's grains; the fermentation raw materials do not require adjustment of the carbon-nitrogen ratio.

[0011] 2) Take the raw materials obtained in step 1) and carry out anaerobic fermentation: Put the fermentation raw materials into the fermentation device, add the fermentation inoculum, mix well and seal, adjust the moisture content to above 90%, and anaerobic ferment at 25-40℃ for 3-7 days.

[0012] In this application, the fermentation device uses a commercially available anaerobic fermenter, and the heating method is selected according to the actual situation, such as water bath, electric heating, etc.

[0013] In this step, the activated sludge is obtained through anaerobic fermentation, and its source is not limited. It is a conventional inoculum in this field. Activated sludge obtained by anaerobic fermentation of vegetable waste or crop straw at a mesophilic temperature (35±2℃) can be used, as well as activated sludge produced by anaerobic fermentation in conventional sewage treatment plants or biogas projects. The amount of activated sludge added is about 15% (v / v). In specific implementation, the fermentation material should preferably account for 80% (v / v) of the total volume of the reactor. After fermentation is completed as described in step 3), the fermentation liquid and residue are separated. The separated fermentation liquid is evenly sprayed onto the surface of the manure at a rate of 2-8 mL / kg, with a spraying frequency of once every 12-48 hours until the end of storage. This can suppress odor emissions during the storage of manure and achieve synergistic reduction of NH3 and H2S emissions. The storage time for this manure is generally 1-30 days.

[0014] In this application, the fermentation liquid used in step 3) is the liquid (acidified liquid) after solid-liquid separation after anaerobic fermentation of vegetable tails. It contains microorganisms such as acid-producing bacteria and hydrogen-producing and acetic acid-producing bacteria. Its total organic acid content is generally 30-120 mmol / L, of which acetic acid accounts for more than 90%. The solid residue after solid-liquid separation can be used as fermentation inoculum or for subsequent composting. The acidified solution prepared by this method is rich in acetic acid (CH3COOH), which can undergo neutralization and condensation reactions with NH3 molecules. The organic acid acidification is unfavorable to the activity of *Pseudomonas putida*, thereby inhibiting the degradation of sulfur-containing organic matter by microorganisms such as *Pseudomonas putida* into MT, DMS, and DMDS, reducing the substrate for H2S production. At the same time, the organic acid contains acid-producing bacteria, hydrogen-producing and acetic acid-producing bacteria, which may promote the conversion of sulfur-oxidizing bacteria into sulfates or elemental sulfur, reducing the release of H2S. In addition, the soluble organic matter (DOM) in the acidified solution is rich in functional groups such as phenolic hydroxyl and carboxyl groups, which are beneficial for odor adsorption, thus achieving a synergistic reduction of NH3 and H2S.

[0015] In this application, the term "odor" includes, but is not limited to, at least one of NH3 and H2S; the manure storage process refers to the temporary storage of manure and sewage by livestock farms, composting plants or centralized waste treatment centers, etc., with a storage time generally ranging from 1 to 30 days.

[0016] Compared with existing methods for reducing NH3 and H2S emissions during organic waste storage, the method of this invention has the following advantages:

[0017] 1) This application uses anaerobic fermentation acidification liquid to treat livestock and poultry manure, which can simultaneously and effectively reduce NH3 and H2S emissions and effectively remove odor during manure storage. The acid preparation operation is simple and can inhibit the growth of malodorous Pseudomonas microorganisms in the fermentation pile and promote the growth of sulfur-oxidizing microorganisms. It has a good synergistic inhibitory effect on NH3 and H2S emissions during manure storage, with emission reductions of 31.0% to 47.0% and 35.2% to 96.7%, respectively, which are significantly higher than the 17-25% (NH3) and 12-45% (H2S) emission reductions reported in the prior art using ordinary organic acids.

[0018] 2) The organic acid production method of this invention is simple and has no risk of secondary pollution. The acidification liquid used is derived from organic waste such as vegetable waste, straw, and acidic waste residue through anaerobic digestion and fermentation. The organic acid production efficiency is high, which is conducive to the harmless treatment of waste and its transformation into beneficial substances. It can also significantly reduce the loss of nutrients during the storage of manure and sewage, which is conducive to its subsequent resource utilization and achieves synergy between odor reduction and waste resource recycling.

[0019] 3) The acidification liquid in this application has a small spraying amount and high stability, which reduces the difficulty of operation and the energy consumption of treatment. The material obtained after treatment in this application is generally used as raw material for organic fertilizer or biogas fermentation. On the one hand, the acidification treatment of the material is conducive to reducing greenhouse gas emissions in the aerobic composting process and promoting the formation of humic acid. On the other hand, it can improve the acid production and biogas production capacity of anaerobic fermentation and improve the efficiency of the industry. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the experimental setup;

[0021] (A) Diagram of anaerobic fermentation device; 1-Sampling port, 2-Fermentation tank, 3-Gas sampling bottle, 4-Exhaust port, 5-Gas delivery pipe, 6-Gas collection bottle, 7-Water delivery pipe, 8-Water collection bottle, 9-Constant temperature water tank.

[0022] (B) Photograph of the actual odor collection device.

[0023] Figure 2 Statistical results of dynamic and cumulative emissions of NH3 and H2S after spraying fermentation acidification liquid;

[0024] The red arrows indicate the spraying time; the differences between the treatment groups were analyzed using one-way ANOVA, and different lowercase letters indicate significant differences between the treatments (P<0.05).

[0025] Figure 3 The statistical results show the effects of the amount and frequency of spraying fermentation acidification liquid on NH3 emissions during chicken manure storage; among them, (A) spraying once every 12 hours; (B) spraying once every 24 hours; (C) spraying once every 48 hours;

[0026] The differences between the acetic acid control group and the experimental group were analyzed using a paired-samples t-test; ** and *** indicate that the differences between the treatment group and the control group are highly significant (P<0.01 and 0.001, respectively).

[0027] Figure 4 Statistical results on the effects of spraying amount and frequency of fermentation acidification liquid on H2S emissions during chicken manure storage; (A) spraying once every 12 hours; (B) spraying once every 24 hours;

[0028] The differences between the acetic acid control group and the experimental group were analyzed using a paired-samples t-test; ns, *, **, and *** represent no significant difference (P>0.05), significant difference (P<0.05), and highly significant difference (P<0.01 and 0.001) between the treatment group and the control group, respectively. Detailed Implementation

[0029] The present invention will be further described in detail with reference to the accompanying drawings and embodiments:

[0030] In the example, the activated sludge was obtained by the applicant at the Liuhe experimental base using vegetable waste anaerobic fermentation at a medium temperature (35±2℃). In specific implementation, activated sludge produced by anaerobic fermentation in sewage treatment plants or biogas projects can also be used.

[0031] Example 1

[0032] The preparation of fermentation acidification broth includes the following steps:

[0033] (1) Preparation of fermentation material: Crush cabbage and tomatoes to about 2cm, add about 15% (v / v) of activated sludge, mix evenly to obtain fermentation material.

[0034] The basic parameters of the experimental materials and the inoculated activated sludge in this embodiment are shown in Table 1. The methods for determining total organic matter and total nitrogen content are as follows: fresh samples were air-dried, ground, and passed through an 80-mesh sieve. Total organic matter was determined using the potassium dichromate oxidation method, and total nitrogen was determined using the Kjeldahl method (for relevant testing methods, please refer to the national standard for organic fertilizers, NY / T525-2021).

[0035] Table 1. Basic Properties of Fermentation Feedstock

[0036] Fermentation raw materials Moisture content (%) Total organic carbon (mg / g) Total nitrogen (mg / g) Carbon-to-nitrogen ratio cabbage 91.9±0.2 455.4±1.8 21.3±0.03 21.4 tomato 95.2±0.08 453.4±0.4 16.6±0.07 27.2 Activated sludge 97.1±0.5 26.9±0.5 33.6±0.5 0.8 chicken manure 78.31±0.3 302.7±0.04 28.9±0.2 10.5

[0037] Note: Mean ± Standard Error (n=3)

[0038] (2) Preparation of fermentation acidification liquid: The fermentation material obtained in step (1) is subjected to anaerobic fermentation treatment. The device is a 10L self-made fermentation tank with a filling degree of about 80%. In specific implementation, other conventional or commercially available anaerobic fermentation tanks can also be used.

[0039] The fermenter structure is as follows: Figure 1 As shown in (A), fermenter 2, water collection bottle 6, and water collection bottle 8 are all sealed tanks connected by a conduit located at the top. Fermenter 2 is placed in a constant temperature water tank 9. The top of fermenter 2 is sealed and has two conduits. One conduit has a valve, with one end close to the top of the fermenting material and the other end serving as a sampling port 1. The other conduit has one end at the top of fermenter 2 and the other end at the top of water collection bottle 6 as a gas guide pipe 5. A gas sampling bottle 3 is located on the gas guide pipe 5 near the fermenter 2. An exhaust port 4 with a valve is located on the gas guide pipe 5 between the gas sampling bottle 3 and water collection bottle 6. A water guide pipe 7 is located between water collection bottle 6 and water collection bottle 8. One end of the water guide pipe 7 is submerged in the liquid inside water collection bottle 6, and the other end is located above the liquid inside water collection bottle 8.

[0040] The total solids (TS) contents of the GL and FQ fermentation systems were 6% and 4%, respectively. The fermentation temperature was 35℃, and a water bath heating method was used. The fermentation time was 5 days. The basic parameters of the fermentation acidification broth in this example are shown in Table 2.

[0041] Table 2. Basic properties of fermentation acidification broth

[0042]

[0043] Note: Mean ± Standard Error (n=3)

[0044] In the specific implementation process, the fermentation material mentioned in step (1) can also be one or more organic wastes such as vegetable waste, straw, and acidic waste residue. The moisture content of the fermentation material is not less than 90%, which can achieve the purpose of this invention.

[0045] Example 2

[0046] The fermentation acidification liquid in Example 1 was used to suppress odor generation during the storage of organic waste. In this example, the static simulation reactor used to store the manure was a 12cm diameter, 2L volume, sealed plastic bucket with a lid; a three-way valve was installed on the top of the lid for gas collection. A photograph of the actual product is shown below. Figure 1 As shown in (B). The manure in this example was taken from a large-scale egg-laying chicken farm in Zhenjiang City, Jiangsu Province.

[0047] The steps included: the total acid content of the cabbage fermentation acidified liquid (GL) and tomato fermentation acidified liquid (FQ) obtained in Example 1 was adjusted to the same concentration (32 mmol / L), and sprayed onto the surface of chicken manure. The spraying method was in accordance with the method disclosed in "Liu Juan, Wang Xuan, Cao Yubo, Bai Zhaohai, Ma Lin. Research and application of ammonia emission reduction technology for manure acidification in livestock farm pens [J]. Chinese Journal of Eco-Agriculture (Chinese and English), 2023, 31(2):290-299". The spraying amount was 4 mL / kg, and the frequency was once every 24 hours, for a total of 4 sprays. At the same time, the treatment of spraying commercial acetic acid (YS) and purified water (CK) was set as the control group. After spraying, the emission of NH3 and H2S in the pile was measured. The measurement method is as follows:

[0048] (1) NH3 emissions:

[0049] Sampling and Measurement Methods: The boric acid absorption method was used for sampling. 20 ml of 2% boric acid was poured into a 50 ml beaker, which was then placed in a static simulation reactor and sealed for 1 hour. After 1 hour, the beaker was removed, and 5 ml of the boric acid absorption solution was pipetted into a colorimetric tube. 5 ml each of phenol and sodium hypochlorite were added sequentially, the tube was sealed, and the mixture was allowed to stand for 2 hours. The volume was then adjusted to 50 ml with distilled water. The spectrophotometer was adjusted to 625 nm, zeroed with distilled water, and the sample was measured. Data were recorded.

[0050] The formula for calculating NH3 emission flux is as follows:

[0051]

[0052] In the formula, F is the emission flux of NH3, mg / kg / h; C is the concentration of ammonia nitrogen in the dilution solution, mg / L; 0.02 is the volume of boric acid absorption solution, L; 17 is the relative molecular mass of NH3; M is the mass of pig manure in each test tank, kg; t is the NH3 absorption time, min; 14 is the relative molecular mass of N; 60 is the number of minutes per hour.

[0053] Cumulative NH3 emissions are calculated by weighting emission rates over time intervals, using the following formula:

[0054]

[0055] In the formula, T represents the cumulative NH3 emissions, in mg / kg; F i and F i+1 D represents the emission fluxes for the i-th and i+1-th events, in mg / kg / h. i and D i+1 Let h be the sampling time for the i-th and (i+1)-th times.

[0056] (2) H2S emissions:

[0057] Sampling and Measurement Methods: Immediately after spraying the fermentation acidification liquid, the container was sealed. Gas was collected using a 100mL syringe equipped with a three-way valve and stored in a 100mL gas collection bag (LBD-100mL, Shanghai Shenyuan Scientific Instruments Co., Ltd., China). Collection times were 0, 5, 10, and 15 minutes after sealing. After gas collection, H2S concentration was determined using a gas chromatograph (GC9890AS, Shanghai Star Analytical Instruments Co., Ltd., China).

[0058]

[0059] In the formula, F H2S 1. H2S emission flux, mg / kg / h; 60, min / h; H, height from the fecal surface to the rim of the container, cm; 34.08, molar mass of H2S, g / mol; 8.21, gas volume conversion factor; K, slope of the linear equation for gas concentration, ppm / min; T, temperature during gas sampling, °C; 0.011, surface area of ​​1 kg of feces in this experimental setup, m². 2 .

[0060] H2S cumulative emissions reference formula (3).

[0061] The test results are as follows Figure 2 As shown: After spraying the fermentation acidification liquid, the NH3 emission flux decreased significantly. Figure 2 (As shown in Figure A). During the 96-hour test period, the cumulative NH3 emissions for each treatment were 29.6, 24.15, 15.37, and 12.80 mg / kg, respectively. Figure 2 (As shown in Figure B). Compared with CK, the cumulative NH3 emissions decreased by 48.1% and 56.8% respectively after spraying GL and FQ, with significant reductions (P<0.05); compared with YS, the cumulative NH3 emissions decreased by 36.4% and 47.0% respectively after spraying GL and FQ, with significant reductions (P<0.05). Spraying fermentation acidification liquid has a significant inhibitory effect on H2S emissions ( Figure 2 As shown in Figure C), during the 96-hour experimental period, the cumulative H2S emissions for each treatment were 0.077, 0.076, 0.019, and 0.024 mg / kg, respectively. Figure 2 (As shown in D). Compared with CK, the cumulative H2S emissions decreased by 75.3% and 69.0% respectively after spraying GL and FQ, with significant reductions (P<0.05); compared with YS, the cumulative H2S emissions decreased by 74.9% and 68.5% respectively after spraying GL and FQ, with significant reductions (P<0.05). It is evident that spraying fermentation acidification liquid can effectively inhibit the emission of NH3 and H2S during manure composting, and the effect is significantly better than that of conventional chemical reagent acetic acid.

[0062] Example 3

[0063] The selection of the spraying amount and frequency of the fermentation acidification liquid includes the following steps:

[0064] Using the cabbage fermentation acidification liquid (GL) prepared in Example 1 as an example and commercially available acetic acid (YS) as a control, the spraying methods were the same as in Example 2, with spraying rates set at 2, 4, and 8 mL / kg. Under the same spraying rate, the spraying frequency was once every 12, 24, and 48 hours. After spraying, the emissions of NH3 and H2S from the pile were measured according to the method in Example 2.

[0065] Table 3. Effects of different spraying amounts and frequencies of fermented cabbage acidified liquid on the reduction of NH3 and H2S emissions (unit: %)

[0066]

[0067]

[0068] During the 96-hour test period, the cumulative NH3 emissions of each treatment were as follows: Figure 3 As shown, spraying GL significantly reduced NH3 emissions from the heap (P<0.01 and 0.001). The spraying amount had a significantly better inhibitory effect on NH3 emissions than the spraying frequency (Table 3).

[0069] During the 96-hour test period, the cumulative H2S emissions of each treatment were as follows: Figure 4 As shown, the application rate generally had a good inhibitory effect on H2S emissions. The treatment with an application rate of 8 mL / kg showed significantly lower H2S emissions than other application rates. Compared with the YS control, spraying GL every 24 hours significantly (P<0.001) reduced the H2S emissions from the heap. Figure 4 As shown in Figure B), its emission reduction effect is also better than other spraying frequency treatments. Figure 4 (As shown in A).

[0070] Table 3 shows the emission reduction effects of different spraying amounts and frequencies of fermented cabbage acidification liquid on NH3 and H2S. Considering the emission reduction effects of the two main odor gases, and taking into account energy consumption and labor costs, the recommended spraying strategy is: spraying amount of 8 mL / kg, once every 24 hours.

[0071] Although the present invention has been described in detail above with general description and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for suppressing odor emissions during the storage of fecal waste using fermented acidified liquid, characterized in that, The specific steps are as follows: 1) The organic waste is crushed and used as a fermentation raw material; the organic waste is an acidic material; 2) Load the fermentation raw materials into the fermentation tank, add activated sludge, adjust the moisture content of the fermentation material to above 90%, and anaerobic ferment at 25~40℃ for 3~7 days; 3) After fermentation, separate the fermentation liquid from the residue. Spray the separated fermentation liquid evenly onto the surface of the manure. The spraying amount is 2~8 mL / kg, and the spraying frequency is once every 12~48 hours until the end of storage. This will suppress the odor emission during the storage of manure.

2. The method for suppressing odor emissions during the storage of feces using fermented acidified liquid according to claim 1, characterized in that, The acidic material mentioned in step 1) includes at least one of straw, vegetable waste, and distiller's grains.

3. The method for suppressing odor emissions during manure storage using fermentation acidification liquid according to claim 1, characterized in that, The fermentation material mentioned in step 2) accounts for 80% of the total volume of the fermenter.

4. The method for suppressing odor emissions during the storage of feces using fermentation acidification liquid according to claim 1, characterized in that, Step 2) The amount of activated sludge added is 15% of the volume of the fermentation raw materials.

5. The method for suppressing odor emissions during the storage of feces using fermented acidified liquid according to claim 1, characterized in that, The odorous gases mentioned in step 3) include NH3 and H2S.

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