Compound microbial agent and application thereof in municipal sludge drying

Abstract

The invention discloses a compound microbial agent and application thereof in municipal sludge drying, and belongs to the technical field of biology. The method comprises the following steps: mixing municipal sludge and corn straw, and adjusting the water content to 60-70%; then adding a compound microorganism bacterium agent (comprising bacillus subtilis, bacillus licheniformis, common thermoactinomycetes, ureibacillus hydrotrophicus and saccharomycopsis fibuligera); and uniformly mixing the materials containing the compound microbial agent, and implanting the mixture into a fermentation tank. A certain ventilation amount is maintained through a fermentation tank system, and a pile gt is fermented in the fermentation process; the temperature can be maintained for more than 10 days at 90 DEG C, and the fermentation is finished after 10-13 days, so that the moisture content is obviously reduced, and the rapid and efficient dehydration of the municipal sludge is realized. According to the technology, rapid decomposition of municipal sludge materials can be achieved, the water content is greatly reduced, the drying period is remarkably shortened, the operation process is simple, and the technology is a microbial compound flora and technology for rapidly achieving dewatering and drying of municipal sludge.

Description

Technical Field

[0001] The present invention belongs to the field of biotechnological applications, and particularly relates to a composite microbial inoculant and its application in urban sludge drying. Background Art

[0002] With the expansion of the urban population and the improvement of people's living standards in China, the domestic and industrial water consumption has been continuously increasing, resulting in a year-on-year increase in the sewage treatment volume of urban sewage treatment plants. At the same time, the output of dewatered sludge after pressure filtration has also been expanding year by year, and the problems of sludge treatment and disposal need to be solved. According to the statistics of the Ministry of Housing and Urban-Rural Development, the annual output of municipal sludge in China has exceeded 60 million tons by the end of 2020, and it is expected that the annual output of municipal sludge in China will exceed 100 million tons by 2025. Contrary to the rapid development of sewage treatment, the development of sludge treatment and disposal and related technologies is very slow. At present, the dewatered sludge produced by urban sewage treatment plants has problems such as high moisture content and unstable biochemical properties. In order to reduce its impact on the environment and lower the disposal cost, it is necessary to carry out drying treatment, which is also the key to solving the sludge disposal problem at present. And currently, the sludge biological drying technology, as a new type of green and energy-saving drying technology, provides heat through the fermentation heat production of natural microorganisms and external air blowing, so as to reduce the moisture of dewatered sludge.

[0003] The sludge drying technology is an important link in the sewage treatment process, and its main purpose is to reduce the moisture in the sludge for subsequent treatment or utilization. There are many types of sludge drying and dewatering technologies, which can be divided into the following categories: thermal drying technology, mechanical pressure filtration drying technology, microwave drying technology, biological drying technology, etc.; the sludge biological drying technology has attracted the attention of researchers due to its unique advantages. In Chinese Patent CN102381822A, a process method for using a multi-strain composite microorganism to rapidly decompose sludge at high temperature can rapidly reduce the volume of sludge, and the volume of sludge is reduced to about 1 / 5 of the original. Chinese Patent CN102851246A shows that traditional composting generally uses indigenous microorganisms in the composting materials, and there are often problems such as long fermentation time, serious odor pollution and low maturity. By inoculating microbial agents at the initial stage of composting, the composting efficiency and the quality of the finished product can be improved. The mechanisms for inoculating microorganisms to promote compost maturity are: 1) increasing the population of microorganisms at the initial stage of composting and enhancing the degradation activity of microorganisms; 2) shortening the time to reach the high-temperature stage; 3) inoculating microorganisms with strong ability to decompose organic substances. Some thermophilic bacteria, mesophilic bacteria, actinomycetes and fungi isolated from compost are often used as compost inoculants to accelerate the hydrolysis of cell walls and lignin and cellulose, and promote the humification process. Chinese Patent CN111979156A shows that by adding a microbial composition formed by thermophilic bacteria and applying it to the resource utilization of urban sludge, the fermentation temperature can be 30-40 °C higher than that of traditional sludge composting, which can significantly shorten the fermentation cycle, simplify the process and strengthen the harmless effect. Summary of the Invention

[0004] Objective of the Invention: The technical problem to be solved by the present invention is to provide a compound microbial inoculant and its application in urban sludge drying in view of the deficiencies of the prior art. The present invention provides a method for ultra-high temperature fermentation of microbial biomass energy conversion. Using this method to treat urban sludge, the fermentation period is short, the harmless treatment is thorough, the deodorization effect is good, and at the same time, the resource utilization of urban sludge can be better realized.

[0005] To solve the above technical problems, the present invention discloses a compound microbial inoculant and its application in urban sludge drying. The specific technical solutions are as follows:

[0006] A compound microbial inoculant, which comprises a combination of Bacillus licheniformis, Bacillus velezensis, Ureibacillus suwonensis, Bacillus subtilis, Thermoactinomyces vulgaris and Saccharomycopsis fibuligera.

[0007] Among them, the Bacillus licheniformis has a taxonomic name of Bacillus licheniformis, a strain number of JAAS-21, a preservation number of GDMCC No: 63662, and a preservation time of July 18, 2023;

[0008] The Bacillus velezensis has a taxonomic name of Bacillus velezensis, a strain number of JAAS-22, a preservation number of GDMCC No: 63724, and a preservation time of August 10, 2023;

[0009] The Ureibacillus suwonensis has a taxonomic name of Ureibacillus suwonensis, a strain number of JAAS-41, a preservation number of GDMCC No: 65934, and a preservation time of February 20, 2025;

[0010] The Bacillus subtilis has a taxonomic name of Bacillus subtilis and a preservation number of CICC10028;

[0011] The Thermoactinomyces vulgaris has a taxonomic name of Thermoactinomyces vulgaris and a preservation number of CICC 10650;

[0012] The Saccharomycopsis fibuligera has a taxonomic name of Saccharomycopsis fibuligera and a preservation number of CICC 1717. Among them, in the compound microbial inoculant, the concentration of Bacillus subtilis is 1-7×10 8 CFU / mL, and the concentration of Bacillus licheniformis is 1-5×10 8CFU / mL, the concentration of Bacillus velezensis is 2 - 7×10 8 CFU / mL, the concentration of Thermoactinomyces vulgaris is 1 - 5×10 7 CFU / mL, the concentration of Ureibacillus suwonensis is 1 - 5×10 7 CFU / mL, the concentration of Saccharomycopsis fibuligera is 1 - 5×10 8 CFU / mL. Preferably, the content of Bacillus subtilis is 1 - 2×10 8 CFU / mL, the content of Bacillus licheniformis is 3 - 5×10 8 CFU / mL, the content of Bacillus velezensis is 3 - 4×10 8 CFU / mL, the content of Thermoactinomyces vulgaris is 2 - 4×10 7 CFU / mL, the content of Ureibacillus suwonensis is 2 - 3×10 7 CFU / mL, the content of Saccharomycopsis fibuligera is 1 - 2×10 8 CFU / mL.

[0013] In a second aspect, the present invention provides a method for preparing the compound microbial inoculant described in the first aspect, including the following steps: fermentatively culturing Bacillus licheniformis, Bacillus velezensis, Ureibacillus suwonensis, Bacillus subtilis, Thermoactinomyces vulgaris and Saccharomycopsis fibuligera respectively to obtain Bacillus licheniformis fermentation broth, Bacillus velezensis fermentation broth, Ureibacillus suwonensis fermentation broth, Bacillus subtilis fermentation broth, Thermoactinomyces vulgaris fermentation broth and Saccharomycopsis fibuligera fermentation broth, and mixing them to obtain the compound microbial inoculant.

[0014] Among them, the fermentation temperature of the Bacillus licheniformis is 35 - 38°C, and the fermentation time is 48 - 50h, preferably 37°C, 48h. The fermentation temperature of the Bacillus velezensis is 35 - 38°C, and the fermentation time is 48 - 50h, preferably 37°C, 48h. The fermentation temperature of the Bacillus subtilis is 35 - 38°C, and the fermentation time is 48 - 50h, preferably 37°C, 48h. The fermentation temperature of the Thermoactinomyces vulgaris is 50 - 60°C, and the fermentation time is 50 - 55h; preferably 55°C, 52h. The fermentation temperature of the Ureibacillus suwonensis is 50 - 60°C, and the fermentation time is 50 - 55h, preferably 55°C, 52h. The fermentation temperature of the Saccharomycopsis fibuligera is 28 - 32°C, and the fermentation time is 48 - 50h. Preferably 30°C, 48h.

[0015] Further preferably, the fermentation medium used in the fermentation processes of Bacillus licheniformis, Bacillus velezensis, Bacillus ureae proomii, Bacillus subtilis, Thermoactinomyces vulgaris and Saccharomycopsis fibuligera includes: corn steep powder 5 g / L, yeast powder 5 g / L, sodium chloride 5 g / L, glucose 10 g / L, tryptone 2 g / L and molasses 10 g / L.

[0016] Among them, in the mixing of the fermentation broth of Bacillus licheniformis, Bacillus velezensis, Bacillus ureae proomii, Bacillus subtilis, Thermoactinomyces vulgaris and Saccharomycopsis fibuligera, the mixing volume ratio is 0.5 - 1.5:0.5 - 1.5:0.5 - 1.5:0.5 - 1.5:0.5 - 1.5:0.5 - 1.5, preferably 1:1:1:1:1:1.

[0017] Preferably, the fermentation broth is obtained by large-scale production in a fermenter in sequence.

[0018] In the third aspect, the present invention provides the application of the compound microbial inoculum described in the first aspect in the drying of municipal sludge.

[0019] Among them, the compound microbial inoculum is inoculated into the mixture of municipal sludge and corn straw for aerobic fermentation, so as to dry the municipal sludge.

[0020] Among them, in the mixture of municipal sludge and corn straw, the mixing mass ratio of municipal sludge to corn straw is 0.5 - 2:1, preferably 1:1; the inoculation amount of the compound microbial inoculum is 1 - 5‰ v / v, preferably 3‰ v / v.

[0021] Among them, for the aerobic fermentation, the fermentation period is 10 - 13 days. The aerobic fermentation is high-temperature aerobic fermentation, and the temperature of the pile body can be raised to 90°C within 24 hours. After 12 days of high-temperature composting, the moisture content drops from 60 - 65% to 30 - 35%, the high temperature can be maintained for more than 10 days, and the pile body is reduced by 30%.

[0022] Beneficial effects:

[0023] The present invention discloses a compound microbial inoculum, which includes a combination of Bacillus licheniformis, Bacillus velezensis, Bacillus ureae proomii, Bacillus subtilis, Thermoactinomyces vulgaris and Saccharomycopsis fibuligera. Using the compound microbial inoculum to treat municipal sludge can achieve the rapid composting of municipal sludge materials, significantly reduce the moisture content, significantly shorten the drying period, and the operation process is simple. It is a compound microbial inoculum and process for quickly realizing the dehydration and drying of municipal sludge. Description of the drawings

[0024] The following further specifically describes the present invention in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become clearer.

[0025] Figure 1 It is a hydrolysis clear zone plate for high protease activity strains. Among them, A is the original urea Bacillus subtilis cultured at 55°C, B is Bacillus velezensis cultured at 37°C, and C is Saccharomycopsis fibuligera cultured at 30°C.

[0026] Figure 2 It is a hydrolysis clear zone plate for high amylase activity strains. Among them, A is Bacillus subtilis cultured at 37°C, B is Bacillus velezensis cultured at 37°C, and C is Saccharomycopsis fibuligera cultured at 30°C.

[0027] Figure 3 It is a hydrolysis clear zone plate for high lipase activity strains. Among them, A is Thermoactinomyces vulgaris cultured at 55°C, B is Bacillus subtilis cultured at 37°C, and C is Bacillus licheniformis cultured at 37°C.

[0028] Figure 4 It is a hydrolysis clear zone plate for high cellulase activity strains. Among them, A is Thermoactinomyces vulgaris cultured at 55°C, B is Bacillus subtilis cultured at 37°C, and C is Bacillus licheniformis cultured at 37°C.

[0029] Figure 5 It is a diagram of the material properties of different treatment stages of pile 1. Among them, A is a physical picture of pile 1 at the initial mixing stage, B is the pile property of pile 1 after composting, C is that the temperature of pile 1 can reach 97°C during the fermentation process, D is a physical picture of pile 1 during the fermentation process, and E is the changing trend of the composting temperature and moisture content of pile 1 with the treatment time. Figure 6 It is a diagram of the material properties of different treatment stages of pile 2. Among them, A is a physical picture of pile 2 at the initial mixing stage, B is the pile property of pile 2 after composting, C is that the temperature of pile 2 can reach 98°C during the fermentation process, D is a physical picture of pile 2 during the fermentation process, and E is the changing trend of the composting temperature and moisture content of pile 2 with the treatment time. Specific Embodiments

[0030] The present invention is described in detail below through specific examples, but the protection scope of the present invention is not limited. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can all be obtained from commercial channels.

[0031] Example 1 Screening of High Enzyme Activity Microbial Strains

[0032] Prepare screening plates for protease, amylase, lipase, and cellulase. The preparation methods are as follows:

[0033] Protease screening plate: agar 20 g / L, skim milk 2% (g / mL); sterilize at 121 °C for 15 min.

[0034] Amylase screening plate: soluble starch 2.5 g / L, peptone 5 g / L, ammonium sulfate 2.5 g / L, potassium dihydrogen phosphate 3 g / L, calcium chloride hexahydrate 0.25 g / L, agar 20 g / L; sterilize at 121 °C for 15 min, and add 1 mL of Lugol's iodine solution after culturing to show the hydrolysis zone.

[0035] Lipase screening plate: yeast extract 2.5 g / L, tryptone 2.5 g / L, agar 12 g / L, adjust the pH to 7 ± 0.1, then add bromocresol purple, sterilize at 121 °C for 15 min, cool to 50 - 55 °C, and add tributyrin 20 mL / L; (the color of the plate is purple).

[0036] Cellulase screening plate: sodium nitrate 1 g / L, disodium hydrogen phosphate 1.2 g / L, potassium dihydrogen phosphate 0.9 g / L, magnesium sulfate 0.5 g / L, potassium chloride 0.5 g / L, yeast extract powder 0.5 g / L, acid hydrolyzed casein 0.5 g / L, congo red 0.2 g / L, cellulose powder 5 g / L, agar 15 g / L, pH value ± 0.1. After culturing, soak with 1 mol / L sodium chloride solution for 15 minutes, then pour out the sodium chloride solution and observe the hydrolysis zone.

[0037] Screening method for high enzyme activity microbial strains: After liquid activation culture of the sludge drying and manure composting related strains preserved in this laboratory, take 5 μL of the bacterial solution and drop it onto the screening plates of protease, amylase, lipase and cellulase, and culture at 30 °C, 37 °C and 55 °C for 24 hours respectively. Taking the size of the transparent zone as an index, screen out the target strains with high enzyme activity.

[0038] 1. Screening of strains with high protease activity:

[0039] Under the culture at 55 °C, 2 strains with high protease activity were screened out, namely Bacillus ureolyticus and Thermoactinomyces vulgaris;

[0040] Under the culture at 37 °C, 3 strains with high protease activity were screened out, namely Bacillus subtilis, Bacillus licheniformis and Bacillus velezensis;

[0041] Under the culture at 30 °C, 1 strain with high protease activity was screened out, which is Saccharomycopsis fibuligera.

[0042] Under the culture at 3 different temperatures, the hydrolysis transparent zones of the strains with high protease activity screened out are as Figure 1 shown.

[0043] 2. Screening of strains with high amylase activity:

[0044] Strains that did not show amylase activity when cultured at 55°C.

[0045] When cultured at 37°C, 2 strains with high amylase activity were screened, namely Bacillus subtilis and Bacillus velezensis.

[0046] When cultured at 30°C, 1 strain with high amylase activity was screened, which is Saccharomycopsis fibuligera.

[0047] The hydrolysis clear zones of the screened strains with high amylase activity are as Figure 2 shown.

[0048] 3. Screening of strains with high lipase activity:

[0049] When cultured at 55°C, 1 strain with high lipase activity was screened, which is Thermoactinomyces vulgaris.

[0050] When cultured at 37°C, 2 strains with high lipase activity were screened, namely Bacillus subtilis and Bacillus licheniformis. No strains with high lipase activity were screened in the target strain library under the condition of 30°C.

[0051] The hydrolysis clear zones of the screened strains with high lipase activity are as Figure 3 shown.

[0052] 4. Screening of strains with high cellulase activity:

[0053] When cultured at 55°C, 2 strains with high cellulase activity were screened, namely Ureibacillus suwonensis and Thermoactinomyces vulgaris.

[0054] When cultured at 37°C, 3 strains with high cellulase activity were screened, namely Bacillus subtilis, Bacillus licheniformis and Bacillus velezensis.

[0055] When cultured at 30°C, 1 strain with high cellulase activity was screened, which is Saccharomycopsis fibuligera.

[0056] The hydrolysis clear zones of the screened strains with high cellulase activity are as Figure 4 shown.

[0057] The relevant data of the hydrolysis zone diameters of the above strains are shown in Table 1.

[0058] Table 1 Maximum diameters of hydrolysis clear zones of target strain enzyme activities

[0059]

[0060] Based on the enzyme activity performance of the above-mentioned strains, the 6 target strains with high enzyme activity screened in the present invention were sent to the company for 16S rDNA sequencing and species confirmation. The sequencing sequence of Bacillus licheniformis is shown in SEQ ID No.1, the sequencing sequence of Bacillus velezensis is shown in SEQ ID No.2, and the sequencing sequence of Ureibacillus suwonensis is shown in SEQ ID No.3. The preservation information of each strain is as follows:

[0061] The Bacillus licheniformis mentioned above is classified and named as Bacillus licheniformis, with the strain number JAAS-21, the preservation number GDMCC No: 63662, the preservation time on July 18, 2023, and is preserved in the Guangdong Provincial Microbial Culture Collection Center (GDMCC), and the preservation address is on the 5th floor of Building 59, No. 100 Yard, Xianlie Middle Road, Guangzhou, Institute of Microbiology, Guangdong Academy of Sciences;

[0062] The Bacillus velezensis mentioned above is classified and named as Bacillus velezensis, with the strain number JAAS-22, the preservation number GDMCC No: 63724, the preservation time on August 10, 2023, and is preserved in the Guangdong Provincial Microbial Culture Collection Center (GDMCC), and the preservation address is on the 5th floor of Building 59, No. 100 Yard, Xianlie Middle Road, Guangzhou, Institute of Microbiology, Guangdong Academy of Sciences;

[0063] The Ureibacillus suwonensis mentioned above is classified as Ureibacillus suwonensis, with the strain number JAAS-41, the preservation number GDMCC No: 65934, the preservation time on February 20, 2025, and is preserved in the Guangdong Provincial Microbial Culture Collection Center (GDMCC), and the preservation address is on the 5th floor of Building 59, No. 100 Yard, Xianlie Middle Road, Guangzhou, Institute of Microbiology, Guangdong Academy of Sciences;

[0064] The other 3 strains are: Thermoactinomyces vulgaris CICC 10650; Bacillus subtilis CICC 10028 and Saccharomycopsis fibuligera CICC 1717.

[0065] The present invention uses the above 6 strains with high enzyme activity to prepare a composite microbial inoculant and applies it to the drying treatment of municipal sludge.

[0066] Example 2 Fermentation Culture and Preparation of Composite Microbial Inoculant

[0067] 1. Seed Liquid Culture

[0068] Bacillus subtilis CICC 10028, Bacillus licheniformis JAAS-21, and Bacillus velezensis JAAS-22 were respectively streaked on an LB solid plate and cultured at 37 °C for 18 - 24 h (20 h in this example); mature single colonies were picked and transferred into 150 mL of LB liquid medium, and the culture conditions were a stirring speed of 100 - 200 rpm (150 rpm in this example), a culture temperature of 37 °C, and a culture time of 18 - 24 h (20 h in this example), which was the first-stage shake flask culture; the first-stage shake flask seed liquid was inoculated into 300 mL of LB liquid medium at an inoculation amount of 5% v / v for the second-stage shake flask culture, and the culture conditions were the same as those of the first-stage shake flask culture, and the second-stage shake flask seed liquids of Bacillus subtilis, Bacillus licheniformis, and Bacillus velezensis were respectively obtained.

[0069] Actinomyces thermohygroscopicus CICC 10650 and Ureibacillus suwonensis JAAS-41 were respectively streaked on an LB solid plate and cultured at 55 °C for 18 - 24 h (20 h in this example); mature single colonies were picked and transferred into 150 mL of LB liquid medium, and the culture conditions were a stirring speed of 100 - 200 rpm (150 rpm in this example), a culture temperature of 55 °C, and a culture time of 18 - 24 h (20 h in this example), which was the first-stage shake flask culture; the first-stage shake flask seed liquid was inoculated into 300 mL of LB liquid medium at an inoculation amount of 5% v / v for the second-stage shake flask culture, and the culture conditions were the same as those of the first-stage shake flask culture, and the second-stage shake flask seed liquids of Actinomyces thermohygroscopicus and Ureibacillus suwonensis were respectively obtained.

[0070] Saccharomycopsis fibuligera CICC 1717 was streaked on a PDA solid plate and cultured at 30 °C for 18 - 24 h (20 h in this example); a mature single colony was picked and transferred into 150 mL of PDA liquid medium, and the culture conditions were a stirring speed of 100 - 200 rpm (150 rpm in this example), a culture temperature of 30 °C, and a culture time of 18 - 24 h (20 h in this example), which was the first-stage shake flask culture; the first-stage shake flask seed liquid was inoculated into 300 mL of PDA liquid medium at an inoculation amount of 5% v / v for the second-stage shake flask culture, and the culture conditions were the same as those of the first-stage shake flask culture, and the second-stage shake flask seed liquid of Saccharomycopsis fibuligera was obtained.

[0071] 2. Fermenter culture and preparation

[0072] Fermenter medium: Corn steep liquor powder 5 g / L, yeast powder 5 g / L, sodium chloride 5 g / L, glucose 10 g / L, tryptone 2 g / L, molasses 10 g / L.

[0073] (1) First-stage seed fermenter culture:

[0074] Transfer the 30L fermentation medium to a 50L seed fermenter, sterilize it at 121°C under high pressure for 20 minutes, inoculate 10% v / v of the Bacillus subtilis secondary shake flask seed solution prepared above, the culture temperature is 37°C, the stirring speed is 200 r / min, and the aeration volume is 0.7 m 3 / h, the culture time is 48 - 50h to obtain the primary seed fermenter fermentation broth. The culture procedures for Bacillus licheniformis and Bacillus velezensis are the same as above.

[0075] Transfer the 30L fermentation medium to a 50L seed fermenter, sterilize it at 121°C under high pressure for 20 minutes, inoculate 10% v / v of the Streptomyces thermotolerans secondary shake flask seed solution prepared above, the culture temperature is 55°C, the stirring speed is 200 r / min, and the aeration volume is 0.7 m 3 / h, the culture time is 50 - 55h to obtain the primary seed fermenter fermentation broth. The culture procedure for Bacillus ureae JAAS - 41 is the same as above, and the culture temperature is 55°C.

[0076] Transfer the 30L fermentation medium to a 50L seed fermenter, sterilize it at 121°C under high pressure for 20 minutes, inoculate 10% v / v of the Saccharomycopsis fibuligera secondary shake flask seed solution prepared above, the culture temperature is 30°C, the stirring speed is 200 r / min, and the aeration volume is 0.7 m 3 / h, the culture time is 48 - 50h to obtain the primary seed fermenter fermentation broth.

[0077] (2) Secondary seed fermenter culture:

[0078] Transfer the 300L fermentation medium to a 500L secondary seed fermenter, sterilize it at 121°C under high pressure for 20 minutes, inoculate 30L of Bacillus subtilis from the primary seed fermenter, the culture temperature is 37°C, the stirring speed is 100 - 150 rpm (130 rpm in this example), and the aeration volume is 7 m 3 / h, the culture time is 48 - 50h to obtain the secondary seed fermenter fermentation broth. The culture procedures for Bacillus licheniformis and Bacillus velezensis are the same as above.

[0079] Transfer the 300L fermentation medium to a 500L secondary seed fermenter, sterilize it at 121°C under high pressure for 20 minutes, inoculate 30L of Streptomyces thermotolerans from the primary seed fermenter, the culture temperature is 55°C, the stirring speed is 100 - 150 r / min (130 rpm in this example), and the aeration volume is 7 m 3 / h, the culture time is 50 - 55h to obtain the secondary seed fermenter fermentation broth. The culture procedure for Bacillus ureae JAAS - 41 is the same as above, and the culture temperature is 55°C.

[0080] Prepare 300L fermentation tank culture medium in a 500L secondary seed fermentation tank, sterilize at 121℃ for 20 minutes, and access 30L of Saccharomyces cerevisiae in the primary seed tank. The culture temperature is 30℃, the stirring speed is 100-150rpm (130rpm in this embodiment), and the ventilation volume is 7m 3 / h, the culture time is 48-50h, and the secondary seed tank fermentation liquid is obtained.

[0081] (3) Expansion and preparation of ton-level fermentation tanks:

[0082] Prepare 3000L fermentation tank medium into 5000L fermentation tank, sterilize at 121℃ for 20 minutes, connect 300L of Bacillus subtilis in the secondary seed tank, culture temperature is 37℃, stirring speed is 60-120rpm (100rpm in this embodiment), ventilation volume is 70-75m 3 / h, the culture time is 48-50h, and the Bacillus subtilis fermentation liquid is obtained. The culture process of Bacillus licheniformis and Bacillus velez is the same as above.

[0083] Prepare 3000L fermentation tank culture medium into 5000L fermentation tank, sterilize at 121℃ for 20 minutes, connect 300L of ordinary high-temperature actinomycetes in the secondary seed tank, culture temperature is 55℃, stirring speed is 60-120rpm (100rpm in this embodiment), ventilation volume is 70-75m 3 / h, the culture time is 50-55h, and the ordinary thermophilic actinomycete fermentation liquid is obtained. The culture process of Suwon urea Bacillus JAAS-41 is the same as above, and the culture temperature is 55℃.

[0084] Prepare 3000L fermentation tank culture medium into 5000L fermentation tank, sterilize at 121℃ for 20 minutes, connect 300L of Saccharomyces cerevisiae in the secondary seed tank, culture temperature is 30℃, stirring speed is 60-120rpm (100rpm in this embodiment), ventilation volume is 70-75m 3 / h, the culture time is 48-50h, and the fermentation liquid of Saccharomyces cerevisiae is obtained.

[0085] The fermentation broths of the above-cultured strains were directly mixed in equal proportions according to a volume ratio of 1:1:1:1:1:1 to obtain a composite microbial agent. The number of viable bacteria in the composite microbial agent was detected, as shown in Table 2.

[0086] Table 2 Results of viable bacterial count detection in composite microbial agents

[0087] Strain name Viable count (CFU / mL) Bacillus subtilis <![CDATA[1.3×10 8 > Bacillus licheniformis <![CDATA[4.1×10 8 > Bacillus velezensis <![CDATA[3.5×10 8 > Actinomadura vulgaris <![CDATA[3.5×10 7 > Ureibacillus suwonensis <![CDATA[2.4×10 7 > Saccharomycopsis fibuligera <![CDATA[1.6×10 8 >

[0088] Example 3 Optimization of the ratio of composite microbial inoculants

[0089] Test materials and substances: Municipal sludge (sludge produced by sewage treatment plants, with a moisture content of 70%-80% after pressure filtration), corn straw, compound microbial inoculant.

[0090] Mix the municipal sludge and corn straw evenly at a mass ratio of 1:1. The moisture content of the municipal sludge is 77%, the moisture content of the corn straw is 40%, and the inoculation volume of the compound microbial inoculant is 3‰ of the volume of the pile body. After mixing, the moisture content is 66%. Inoculate the compound microbial inoculant with the following 6 ratio combinations. The preparation method of the compound microbial inoculant is the same as that in Example 2. The ratio combinations of the compound microbial inoculant are as follows:

[0091] Ratio combination 1: Bacillus licheniformis: Bacillus velezensis: Bacillus ureae proomii: Saccharomycopsis fibuligera, and their fermentation broths are mixed at a volume ratio of 1:1:1:1;

[0092] Ratio combination 2: Bacillus subtilis: Bacillus velezensis: Thermoactinomyces vulgaris: Bacillus ureae proomii, and their fermentation broths are mixed at a volume ratio of 1:1:1:1;

[0093] Ratio combination 3: Bacillus subtilis: Bacillus licheniformis: Thermoactinomyces vulgaris: Bacillus ureae proomii: Saccharomycopsis fibuligera, and their fermentation broths are mixed at a volume ratio of 1:1:1:1:1;

[0094] Ratio combination 4: Bacillus subtilis: Bacillus velezensis: Thermoactinomyces vulgaris: Bacillus ureae proomii: Saccharomycopsis fibuligera, and their fermentation broths are mixed at a volume ratio of 1:1:1:1:1;

[0095] Ratio combination 5: Bacillus licheniformis: Bacillus velezensis: Thermoactinomyces vulgaris: Bacillus ureae proomii: Saccharomycopsis fibuligera, and their fermentation broths are mixed at a volume ratio of 1:1:1:1:1;

[0096] Ratio combination 6: Bacillus subtilis: Bacillus licheniformis: Bacillus velezensis: Thermoactinomyces vulgaris: Bacillus ureae proomii: Saccharomycopsis fibuligera, and their fermentation broths are mixed at a volume ratio of 1:1:1:1:1:1;

[0097] Based on the above ratios, divide them into 6 groups, with the volume of each pile body being 10 cubic meters. There is an air supply pipe at the bottom of the fermentation tank, and air is supplied into the material pile through a blower to ensure the oxygen required for the high-temperature aerobic fermentation process. The ventilation volume is controlled at 0.03 - 0.09m 3 / min; The compost pile is turned over every 48 - 72 hours and enters the next fermentation stage. After 18 - 21 days, the fermentation is completed. The detailed results are shown in Table 3. It can be seen that the drying effect of the mixture ratio combination 6 on the materials is the best, with the highest temperature reaching 80°C, a fermentation cycle of 18 days, and the final moisture content at 38%. Therefore, the mixture ratio combination 6 (Bacillus subtilis: Bacillus licheniformis: Bacillus velezensis: Thermoactinomyces vulgaris: Bacillus ureolyticus: Saccharomycopsis fibuligera, mixed in equal volume ratio of 1:1:1:1:1:1) is selected as the best combination for large-scale testing.

[0098] Table 3 Mixture Ratio of Compound Microbial Inoculant and Results of Small-Scale Testing

[0099] Ratio combination Highest temperature (°C) Period (d) Final moisture content (%) Ratio combination 1 68 21 44 Ratio combination 2 73 21 43 Ratio combination 3 75 18 40 Ratio combination 4 74 18 42 Ratio combination 5 72 21 41 Ratio combination 6 80 18 38

[0100] Example 4 Large-Scale Testing of High-Efficiency Drying and Dewatering of Municipal Sewage Sludge

[0101] Testing Materials and Materials: Municipal sewage sludge (sludge produced by a sewage treatment plant, with a moisture content of 70% - 80% after pressure filtration), corn straw, and the compound microbial inoculant prepared in Example 2.

[0102] 1. High-Efficiency Drying and Dewatering Test Composting Bin 1 for Municipal Sewage Sludge:

[0103] Mix the municipal sewage sludge and corn straw evenly at a mass ratio of 1:1. The moisture content of the municipal sewage sludge is 76.9%, and the moisture content of the corn straw is 40%. Inoculate the compound microbial inoculant prepared in Example 2, with the inoculation volume being 3‰ of the volume of the compost pile. After mixing, the moisture content is 65%, and the total volume is 200 cubic meters. The compost pile is piled up to the top of the fermentation bin. There is an air supply pipe at the bottom of the fermentation bin, and air is supplied into the material pile through a blower to ensure the oxygen required for the high-temperature aerobic fermentation process. The ventilation rate is controlled at 0.03 - 0.09 m 3 / min; Turn over the fermentation compost pile once every 48 hours and carry out the next stage of fermentation. After 10 - 13 days of fermentation, stop the fermentation when the moisture content of the fermentation product is lower than 40% to complete the entire fermentation process. As Figure 5 shown, after 12 days of high-temperature composting, the moisture content drops from 65 - 70% to 30 - 36%, the high temperature of 90°C can be maintained for more than 10 days, and the reduction of the compost pile reaches more than 30%.

[0104] 2. High-Efficiency Drying and Dewatering Test Composting Bin 2 for Municipal Sewage Sludge:

[0105] Mix urban sludge and corn straw evenly at a mass ratio of 1:1. The water content of urban sludge is 73.5%, and the water content of corn straw is 40%. Inoculate the composite microbial inoculant prepared in Example 2. The inoculation volume of the inoculant is 3‰ of the volume of the compost pile. After mixing, the water content is 63%, and the total volume is 200 cubic meters. The compost pile is piled up to the top of the fermentation tank. There is an air supply pipe at the bottom of the fermentation tank, and air is supplied into the material pile through a blower to ensure the oxygen required for the high-temperature aerobic fermentation process. The ventilation volume is controlled at 0.5 m 3 / min; Turn over the fermentation compost pile every 48 hours for the next stage of fermentation. After 10 - 13 days of fermentation, when the water content of the fermentation product is lower than 40%, stop the fermentation to complete the entire fermentation process. As Figure 6 shown, after 12 days of high-temperature composting, the water content drops from 60 - 65% to 30 - 35%, the high temperature of 90°C can be maintained for more than 10 days, and the reduction of the compost pile reaches more than 30%.

[0106] Due to the high fermentation temperature, during the entire 13-day fermentation cycle, the fermentation days above 90°C of the two compost piles exceed 10 days. The bacteria multiply actively under the high-temperature aerobic conditions above 90°C, the water evaporates quickly, the water content of the fermentation product is low, and the reduction is obvious.

[0107] The present invention provides an idea and method for a composite microbial inoculant and its application in the drying of urban sludge. There are many methods and ways to specifically implement this technical solution. The above is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention. Each component not clearly defined in this embodiment can be realized by existing technologies.

Claims

1. A composite microbial agent, characterized in that: It includes a combination of Bacillus licheniformis, Bacillus velez, Bacillus urea, Bacillus subtilis, common thermophilic actinomycetes and Saccharomyces cerevisiae.

2. The composite microbial agent according to claim 1, characterized in that: The Bacillus licheniformis is classified as Bacillus licheniformis, the strain number is JAAS-21, the deposit number is GDMCC No: 63662, and the deposit date is July 18, 2023; The Bacillus velezensis is classified as Bacillus velezensis, the strain number is JAAS-22, the deposit number is GDMCC No: 63724, and the deposit date is August 10, 2023; The Suwon urea bacillus is classified and named Ureibacillus suwonensis, the strain number is JAAS-41, the deposit number is GDMCC No: 65934, and the deposit date is February 20, 2025; The Bacillus subtilis is classified as Bacillus subtilis and its deposit number is CICC 10028; The common thermophilic actinomycetes is classified as Thermoactinomyces vulgaris and its deposit number is CICC10650; The described yeast Saccharomycopsis fibuligera is classified and named Saccharomycopsis fibuligera, and its preservation number is CICC1717.

3. The composite microbial agent according to claim 1, characterized in that: In the composite microbial agent, the concentration of Bacillus subtilis is 1 to 7×10 8 CFU / mL, the concentration of Bacillus licheniformis is 1~5×10 8 CFU / mL, the concentration of Bacillus Velezii is 2~7×10 8 CFU / mL, the concentration of common thermophilic actinomycetes is 1~5×10 7 CFU / mL, the concentration of Suwon Urea Bacillus is 1~5×10 7 CFU / mL, the concentration of Saccharomyces cerevisiae was 1~5×10 8 CFU / mL.

4. The method for preparing the composite microbial agent according to any one of claims 1 to 3, characterized in that: The method comprises the following steps: fermenting and culturing Bacillus licheniformis, Bacillus velez, Suwon urea bacillus, Bacillus subtilis, common thermophilic actinomycetes and Saccharomyces cerevisiae respectively to obtain Bacillus licheniformis fermentation liquid, Bacillus velez fermentation liquid, Suwon urea bacillus fermentation liquid, Bacillus subtilis fermentation liquid, common thermophilic actinomycetes fermentation liquid and Saccharomyces cerevisiae fermentation liquid, and mixing them to obtain the composite microbial agent.

5. The preparation method according to claim 4, characterized in that: The fermentation temperature of the Bacillus licheniformis is 35-38°C, and the fermentation time is 48-50h; The fermentation temperature of the Bacillus Velez is 35-38°C, and the fermentation time is 48-50h; The fermentation temperature of the Bacillus subtilis is 35-38°C, and the fermentation time is 48-50h; The fermentation temperature of the common thermophilic actinomycetes is 50-60°C, and the fermentation time is 50-55h; the fermentation temperature of the Suwon urea bacillus is 50-60°C, and the fermentation time is 50-55h; The fermentation temperature of the Saccharomyces cerevisiae is 28-32° C., and the fermentation time is 48-50 hours.

6. The preparation method according to claim 4, characterized in that: The mixing volume ratio of the mixture of Bacillus licheniformis fermentation liquid, Bacillus velez fermentation liquid, Suwon urea Bacillus fermentation liquid, Bacillus subtilis fermentation liquid, common high-temperature actinomycete fermentation liquid and Saccharomyces cerevisiae fermentation liquid is 0.5-1.5:0.5-1.5:0.5-1.5:0.5-1.5:0.5-1.5:0.5-1.

5.

7. Use of the composite microbial agent according to any one of claims 1 to 3 in drying municipal sludge.

8. The use according to claim 7, characterized in that: The composite microbial agent is inoculated into a mixture of municipal sludge and corn stalks for aerobic fermentation, thereby drying the municipal sludge.

9. The use according to claim 7, characterized in that: In the mixture of municipal sludge and corn stalks, the mass ratio of municipal sludge to corn stalks is 0.5 to 2:1; The inoculation amount of the composite microbial agent is 1-5‰ v / v.

10. The use according to claim 7, characterized in that: The aerobic fermentation has a fermentation period of 10 to 13 days.

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