Sludge high-temperature composting composite microbial agent, preparation method and application thereof

Abstract

The present application belongs to the field of microorganisms, and particularly relates to a sludge high-temperature composting composite microbial agent, a preparation method and application thereof.The specific technical scheme is as follows: a strain of Geobacillus, which was preserved in the China General Microbiological Culture Collection Center on March 29, 2021, and the address of the preservation is No.3, Xili Beichen, Chaoyang District, Beijing, and the preservation number is CGMCC No.22088.A composite microbial agent is provided based on the Geobacillus, and the composite microbial agent further comprises Bacillus ureolyticus and Bacillus subtilis.The composite microbial agent can accelerate the degradation of organic matter in the compost, promote the fermentation and maturation of the compost, shorten the composting time, increase the temperature of the compost, kill the eggs and pathogens contained in the manure, degrade the residual antibiotics and other substances in the compost material, and improve the quality of the fertilizer.

Description

Technical Field

[0001] This invention belongs to the field of microbiology, specifically relating to a high-temperature composting compound microbial agent for sludge, its preparation method, and its application. Background Technology

[0002] In recent years, my country's sludge production has grown rapidly. Currently, the main methods for disposing of sludge in urban wastewater treatment plants in my country are sanitary landfill and even direct open-air dumping. This not only wastes a large amount of usable sludge but also causes secondary pollution and harm to the environment.

[0003] Sludge contains a high content of easily degradable components (water-soluble organic matter, protein, hemicellulose, etc.) and has a relatively strong fertilization capacity, making it an excellent source of organic fertilizer. High-temperature composting can reduce the odor of sludge, effectively kill pathogens, improve sludge properties, enhance its physical properties, and degrade various toxic and harmful substances in the sludge.

[0004] In aerobic composting, temperature changes are closely related to the changes in the number of microbial communities in the compost pile. Most microorganisms cannot carry out normal physiological activities under high temperature conditions; therefore, fewer microorganisms are active during the high-temperature stage of composting, which affects the composting process.

[0005] If a high-temperature composting agent that can be used for sludge composting can be provided, it is expected to accelerate the degradation of organic matter, promote the fermentation and composting of the compost pile, shorten the composting time, and improve the quality of fertilizer. Summary of the Invention

[0006] The purpose of this invention is to provide a high-temperature composting compound microbial agent for sludge, its preparation method, and its application.

[0007] To achieve the above-mentioned objectives, the technical solution adopted in this invention is as follows: A strain of Geobacillus thermodenitrificans was deposited on March 29, 2021, at the China General Microbiological Culture Collection Center, located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, with accession number CGMCCNo.22088.

[0008] Correspondingly, the 16S rDNA sequence of a strain of Geobacillus thermodenitrificans is shown in SEQ ID NO 3.

[0009] Accordingly, the application of Bacillus geysersis in composting.

[0010] Accordingly, a compound microbial agent for composting includes the aforementioned Bacillus geysersis.

[0011] Preferably, it also includes Ureibacillus thermophilus and Bacillus subtilis.

[0012] Preferably, based on the number of live bacteria, the ratio of *Bacillus thermophilus*: *Bacillus subtilis*: *Bacillus thermophilus* = 1–3: 1–2: 2–3.

[0013] Preferably, the viable bacterial concentration of *Bacillus thermophilus*, *Bacillus subtilis*, and *Bacillus thermophilus* is 1 × 10⁻⁶. 8 ~1×10 9 cfu / g.

[0014] Preferably, the thermophilic urealyticum bacillus was deposited on March 29, 2021, at the China General Microbiological Culture Collection Center, at No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing, with accession number CGMCC No. 22086.

[0015] Preferably, the Bacillus subtilis was deposited on March 29, 2021, at the China General Microbiological Culture Collection Center, at No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing, with accession number CGMCCNo. 22087.

[0016] Accordingly, the composting compound microbial agent is obtained by mixing microorganisms with compostable auxiliary materials and drying them.

[0017] The present invention has the following beneficial effects: It provides new microorganisms with extremely strong high-temperature resistance. Based on these microorganisms, a compound microbial agent that can be used for high-temperature composting of sludge is provided, which can accelerate the degradation of organic matter in compost, promote fermentation and maturation of the compost pile, shorten the composting time, increase the temperature of the compost pile, kill insect eggs and pathogens contained in the feces, degrade residual antibiotics and other substances in the compost pile materials, and improve fertilizer quality. Attached Figure Description

[0018] Figure 1 The colony morphology diagram of Bacillus thermophilus provided by this invention;

[0019] Figure 2 Microscopic image of Bacillus thermophilus provided by this invention;

[0020] Figure 3 This is a colony morphology diagram of Bacillus subtilis provided by the present invention;

[0021] Figure 4 Microscopic image of Bacillus subtilis provided by this invention;

[0022] Figure 5This is a colony morphology diagram of Bacillus thermophilus and denitrifying provided by the present invention;

[0023] Figure 6 Microscopic image of Bacillus thermophilus and denitrifying provided by the present invention. Detailed Implementation

[0024] This invention provides a compound microbial agent that can be used for high-temperature composting and decomposition of sludge. The compound microbial agent includes: Ureibacillus thermophilus, Bacillus subtilis, and Geobacillus thermodenitrificans.

[0025] The preferred scheme is: based on the viable count, Bacillus thermophilus urealyticum : Bacillus subtilis : Bacillus thermophilus denitrification = 1-3 : 1-2 : 2-3.

[0026] The preferred formulation is as follows: the viable bacterial concentration of *Bacillus thermophilus*, *Bacillus subtilis*, and *Bacillus thermophilus* in the compound microbial agent is 1 × 10⁻⁶. 8 ~1×10 9 cfu / g.

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art.

[0028] Example 1: Screening, Identification and Preservation of Microorganisms

[0029] 1. Screening process: Weigh 10g of fresh sludge compost sample after high-temperature fermentation, place it in an Erlenmeyer flask containing glass beads and 90mL of sterile water, and shake it in a 30℃ constant temperature shaker for 30min. Then, aspirate the above suspension (10g). -1 10 mL was added to an Erlenmeyer flask containing 90 mL of sterile water, and the solution was added according to the 10... -2 10 -3 10 -4 10 -5 10 -6 10 -7 10 -8 10 -9The compost sample suspension was serially diluted using different dilution factors. Samples of different dilutions were spread onto solid agar plates and incubated upside down at 50℃ and 70℃ for 1–2 days. All single colonies with different characteristics were picked, streaked onto solid agar plates for isolation, and the incubation was repeated three times to obtain pure thermostable bacterial strains, which were then numbered. The medium used for isolation and purification was beef extract peptone agar, containing 3.0 g / L beef extract, 10.0 g / L peptone, 5.0 g / L sodium chloride, and 20 g / L agar powder, adjusted to pH 7.2–7.4, and autoclaved at 121℃ for 30 min.

[0030] Three strains of microorganisms that performed best and were most suitable for high-temperature composting were selected from the isolated microorganisms and identified by 16S rDNA sequencing. Strain X501 was confirmed to be *Bacillus urealyticum*, and its 16S rDNA sequence is shown in SEQ ID NO 1. Its colony morphology is shown in... Figure 1 As shown, the colonies are small, opaque, slightly yellow, dry, flat, and easy to pick up. Their microscopic images are as follows. Figure 2 As shown. The suitable temperature range for the *Bacillus urealyticum* is 30–55℃, with an optimal growth temperature of 50℃. The suitable pH range is 5–9, with an optimal pH of 7.0. Available carbon sources include corn starch, potato starch, and industrial glucose, while nitrogen sources include corn steep liquor, soybean meal, yeast powder, and yeast extract.

[0031] X506 is Bacillus subtilis, and its 16S rDNA sequence is shown in SEQ ID NO 2. Its colony morphology is as follows: Figure 3 As shown, the colonies are white, dry, wrinkled, opaque, and slightly raised. Their microscopic examination image is as follows. Figure 4 As shown. The suitable temperature range for the *Bacillus subtilis* is 30–55℃, with an optimal growth temperature of 50℃. The suitable pH range is 5–9, with an optimal pH of 7.0. Available carbon sources include corn starch, potato starch, and industrial glucose, while nitrogen sources include corn steep liquor, soybean meal, yeast powder, and yeast extract.

[0032] X701 is *Bacillus geosporus*, and its 16S rDNA sequence is shown in SEQ ID NO 3. Its colony morphology is as follows: Figure 5 As shown, the colonies vary in size, are white, and have a rough, opaque surface. Their microscopic images are as follows. Figure 6 As shown. The suitable temperature range for the *Bacillus geysersis* is 40–75℃, with an optimal growth temperature of 60℃. The suitable pH range is 5–9, with an optimal pH of 7.0. Available carbon sources include corn starch, potato starch, and industrial glucose, while nitrogen sources include corn steep liquor, soybean meal, yeast powder, and yeast extract.

[0033] Ureibacillus sp. X501 was deposited on March 29, 2021, at the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, with accession number CGMCC No. 22086. Bacillus subtilis X506 was also deposited on March 29, 2021, at the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, with accession number CGMCC No. 22087. Geobacillus sp. X701 was deposited on March 29, 2021, at the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, with accession number CGMCC No. 22088. It should be noted that the Latin name used in the classification and nomenclature of this deposit is an abbreviation, while the full name is used elsewhere in the text.

[0034] Example 2: Preparation of Compound Microbial Agent and Demonstration of Composting Effect

[0035] 1. Preparation of compound microbial culture medium. The three microorganisms were activated and cultured separately in beef extract peptone medium until reaching 5 × 10⁻⁶ m². 8 The three microorganisms were then mixed with straw powder (60 mesh) at a concentration of cfu / mL. The volume ratio (mL / g) of the total microorganisms to the straw powder was 1:1 to 1:2; in this example, 1:1 was used uniformly. The numbers below each microorganism in Table 1 represent the volume ratio of the microbial culture medium. The mixture was then allowed to stand in a well-ventilated environment to dry, or dried at 50°C with ventilation to accelerate the drying process. The mixture was dried until the moisture content was <10%, yielding 20 sets of compound microbial agents. The *Bacillus urealyticum* under the "Other" column in Table 1 was purchased from the German Microbial Culture Collection Center (accession number DSM17952); *Bacillus subtilis* was purchased from Beijing Beina Chuanglian Biotechnology Research Institute (model BNCC184354); and *Bacillus terrestris* was purchased from Beijing Beina Chuanglian Biotechnology Research Institute (model BNCC161884).

[0036] Table 1 Comparison of Compound Microbial Agent Formulations for Each Group

[0037] Group 1 1，X501 \ \ / Group 2 \ 1，X506 \ / Group 3 \ \ 1，X701 / Group 4 \ 1，X506 2，X701 / Group 5 1，X501 \ 1，X701 / Group 6 2，X501 1，X506 \ / Group 7 0.5，X501 1，X506 2，X701 / Group 8 1，X501 1，X506 2，X701 / Group 9 2，X501 1，X506 2，X701 / Group 10 3，X501 1，X506 2，X701 / Group 11 3.5，X501 1，X506 2，X701 / Group 12 2，X501 0.5，X506 2，X701 / Group 13 2，X501 2，X506 2，X701 / Group 14 2，X501 3，X506 2，X701 / Group 15 2，X501 1，X506 0.5，X701 / Group 16 2，X501 1，X506 1，X701 / Group 17 2，X501 1，X506 3，X701 / Group 18 \ 1，X506 2，X701 2, Bacillus urea, commercially available Group 19 2，X501 \ 2，X701 1, Bacillus subtilis, commercially available Group 20 2，X501 1，X506 \ 2, Bacillus licheniformis, commercially available

[0038] 2. The above-mentioned compound microbial agents are used for high-temperature composting. The composting raw material is: straw powder is mixed into dewatered activated sludge to adjust the moisture content to 55-60%. The straw is corn straw, but wheat straw or rice straw can also be used in practice, with a particle size of 1-3 cm.

[0039] Each group of compound microbial agents was mixed evenly with compost raw materials at a mass ratio of 1:1000, and then piled into mounds approximately 5m long, 3m wide, and 2m high. A control group without any added microbial agents was also included. Each experiment was repeated three times. During the composting process, the mound temperature was monitored daily. Compost temperature measurement: A temperature probe was inserted at the center of the mound along its centerline to detect internal temperature changes. The average of the data collected at 10:00 AM and 4:00 PM each day was taken as the daily mound temperature.

[0040] The day of composting is designated as Day 1. When the pile temperature exceeds 55℃ (generally on the 2nd or 3rd day), sufficient oxygen is provided through the forced aeration system at the bottom of the pile. Turning the pile is unnecessary. The aeration rate can be adjusted based on temperature changes: In the initial heating phase of composting, minimize heat dissipation while meeting the biological oxygen requirements; in the middle, high-temperature phase, control ventilation primarily for heat dissipation to maintain a constant pile temperature (aeration can be increased appropriately when the temperature exceeds 60℃); in the later cooling phase, reduce or stop ventilation to allow for further fermentation of the materials. At the end of composting, moisture can be quickly removed from the finished compost through ventilation as needed.

[0041] When the temperature of the pile body drops below 40°C and no longer rises, the pile enters the post-curing stage. The ammonia nitrogen content in the pile body is monitored regularly every day. When the ammonia nitrogen content is less than 400 mg / kg, the post-curing stage is completed, and the entire pile preparation process ends.

[0042] The period from when the temperature of the compost pile drops below 40°C and stops rising until the ammonia nitrogen content in the compost pile is less than 400 mg / kg is defined as the post-ripening period. The period from the start of composting to the completion of the post-ripening period is defined as the total composting time, i.e., the time taken for the entire composting process. The seed germination index after composting was determined according to Appendix A of the national standard GB / T 23486-2009. The seeds to be germinated were commercially available common Chinese cabbage seeds.

[0043] The results are shown in Table 2.

[0044] Table 2 Comparison of the composting effects of each group of compound microbial agents

[0045]

[0046]

[0047] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Any modifications, alterations, substitutions, or variations made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention shall fall within the protection scope defined by the claims of the present invention. sequence list <110> Sichuan Junhe Environmental Protection Co., Ltd. <120> A high-temperature composting compound microbial agent for sludge, its preparation method and application <160> 3 <170> SIPOSequenceListing 1.0 <210> 1 <211> 1393 <212> DNA <213> Ureibacillus thermophilus <400> 1 ctcaccgact tcgggtgtta cagactctcg tggtgtgacg ggcggtgtgt acaaggcccg 60 ggaacgtatt caccgcggca tgctgatccg cgattactag cgattccggc ttcatgcagg 120 cgagttgcag cctgcaatcc gaactgagag tggctttttg ggattcgctc cccctcgcgg 180 gtttgctgcc ctttgtacca cccattgtag cacgtgtgta gcccaggtca taaggggcat 240 gatgatttga cgtcatcccc accttcctcc gtatttgtac ggcagtctcc ttagagtgcc 300 caactgaatg atggcaacta aggacaaggg ttgcgctcgt tgcgggactt aacccaacat 360 ctcacgacac gagctgacga caaccatgca ccacctgtca ccgctgtccc cgaagggaaa 420 gccatgtctc catggcggtc agcgggatgt caagacctgg taaggttctt cgcgttgctt 480 cgaattaaac cacatgctcc accgcttgtg cgggcccccg tcaattcctt tgagtttcag 540 tcttgcgacc gtactcccca ggcggagtgc ttaatgcgtt agctgcagca ctaaggggcg 600 gaaaccccct aacacctagc actcatcgtt tacggcgtgg actaccaggg tatctaatcc 660 tgtttgctcc ccacgctttc gcgcctcagc gtcagttaca ggccaggaag ccgccttcgc 720 cactggtgtt cctccatatc tctacgcatt tcaccgctac acatggaatt ccgcttccct 780 ctcctgcact caagtctccc agtttccaat gaccctcccc ggttgagccg ggggctttca 840 catcagactt aagagaccgc ctgcgcgcgc tttacgccca ataattccgg acaacgcttg 900 ccacctacgt attaccgcgg ctgctggcac gtagttagcc gtggctttct agtaaggtac 960 cgtcagggcg cagccagtga ctgctgcgct tgttcttccc ttacaacaga gctttacgat 1020 ccgaagacct tcttcgctca cgcggcgttg ctccatcagg ctttcgccca ttgtggaaga 1080 ttccctactg ctgcctcccg taggagtctg ggccgtgtct cagtcccagt gtggccgatc 1140 accctctcag gtcggctacg catcgtcgcc ttggtaggcc gttaccccac caactagcta 1200 atgcgccgcg ggcccatcct atagtgatag cagaaccatc tttcaacccc gaagcatgcg 1260 cttcggtgtg ttatccggta ttagcacgcg tttccgcgag ttatcccggt ctatagggca 1320 ggttacccac gtgttactca cccgtccgcc gctaaccaat taaaaagcaa gcttctaatt 1380 gtccgctcga ctg 1393 <210> 2 <211> 1466 <212> DNA <213> Bacillus subtilis <400> 2 ggggcatcct gggatgcggg tctatcatgc agtcgagcgg acagatggga gcttgctccc 60 tgatgttagc ggcggacggg tgagtaacac gtgggtaacc tgcctgtaag actgggataa 120 ctccgggaaa ccggggctaa taccggatgg ttgtttgaac cgcatggttc agacataaaa 180 ggtggcttcg gctaccactt acagatggac ccgcggcgca ttagctagtt ggtgaggtaa 240 cggctcacca aggcgacgat gcgtagccga cctgagaggg tgatcggcca cactgggact 300 gagacacggc ccagactcct acgggaggca gcagtaggga atcttccgca atggacgaaa 360 gtctgacgga gcaacgccgc gtgagtgatg aaggttttcg gatcgtaaag ctctgttgtt 420 agggaagaac aagtgccgtt caaatagggc ggcaccttga cggtacctaa ccagaaagcc 480 acggctaact acgtgccagc agccgcggta atacgtaggt ggcaagcgtt gtccggaatt 540 attgggcgta aagggctcgc aggcggtttc ttaagtctga tgtgaaagcc cccggctcaa 600 ccggggaggg tcattggaaa ctggggaact tgagtgcaga agaggagagt ggaattccac 660 gtgtagcggt gaaatgcgta gagatgtgga ggaacaccag tggcgaaggc gactctctgg 720 tctgtaactg acgctgagga gcgaaagcgt ggggagcgaa caggattaga taccctggta 780 gtccacgccg taaacgatga gtgctaagtg ttagggggtt tccgcccctt agtgctgcag 840 ctaacgcatt aagcactccg cctggggagt acggtcgcaa gactgaaact caaaggaatt 900 gacgggggcc cgcacaagcg gtggagcatg tggtttaatt cgaagcaacg cgaagaacct 960 taccaggtct tgacatcctc tgacaatcct agagatagga cgtccccttc gggggcagag 1020 tgacaggtgg tgcatggttg tcgtcagctc gtgtcgtgag atgttgggtt aagtcccgca 1080 acgagcgcaa cccttgatct tagttgccag cattcagttg ggcactctaa ggtgactgcc 1140 ggtgacaaac cggaggaagg tggggatgac gtcaaatcat catgcccctt atgacctggg 1200 ctacacacgt gctacaatgg acagaacaaa gggcagcgaa accgcgaggt taagccaatc 1260 ccacaaatct gttctcagtt cggatcgcag tctgcaactc gactgcgtga agctggaatc 1320 gctagtaatc gcggatcagc atgccgcggt gaatacgttc ccgggccttg tacacaccgc 1380 ccgtcacacc acgagagttt gtaacacccg aagtcggtga ggtaaccttt aggagccagc 1440 cgccgaaggt gacaatgttt gccttt 1466 <210> 3 <211> 1456 <212> DNA <213> Geobacillus thermodenitrificans <400> 3 gctggcggtg ctataatgca gtcgagcgga ccgaacgaga gcttgctctt gtttggtcag 60 cggcggacgg gtgagtaaca cgtgggcaac ctgcccgcaa gaccgggata actccgggaa 120 accggagcta ataccggata acaccaaaga ccgcatggtc tttggttgaa aggcggcttc 180 ggctgccact tgcggatggg cccgcggcgc attagctagt tggtgaggta acggctcacc 240 aaggcgacga tgcgtagccg gcctgagagg gtgaccggcc acactgggac tgagacacgg 300 cccagactcc tacgggaggc agcagtaggg aatcttccgc aatggacgaa agtctgacgg 360 agcgacgccg cgtgagcgaa gaaggccttc gggtcgtaaa gctctgttgt gagggacgaa 420 ggagcgccgt ttgaataagg cggcgcggtg acggtacctc acgagaaagc cccggctaac 480 tacgtgccag cagccgcggt aatacgtagg gggcgagcgt tgtccggaat tattgggcgt 540 aaagcgcgcg caggcggtcc tttaagtctg atgtgaaagc ccacggctca accgtggagg 600 gtcattggaa actgggggac ttgagtgcag gagaggagag cggaattcca cgtgtagcgg 660 tgaaatgcgt agagatgtgg aggaacacca gtggcgaagg cggctctctg gcctgtaact 720 gacgctgagg cgcgaaagcg tggggagcaa acaggattag ataccctggt agtccacgcc 780 gtaaacgatg agtgctaagt gttagagggg tcacaccctt tagtgctgta gctaacgcga 840 taagcactcc gcctggggag tacggccgca aggctgaaac tcaaaggaat tgacgggggc 900 ccgcacaagc ggtggagcat gtggtttaat tcgaagcaac gcgaagaacc ttaccaggtc 960 ttgacatccc ctgacaaccc aagagattgg gcgttccccc ttcgggggga cagggtgaca 1020 ggtggtgcat ggttgtcgtc agctcgtgtc gtgagatgtt gggttaagtc ccgcaacgag 1080 cgcaaccctt gcctctagtt gccagcattc agttgggcac tctagaggga ctgccggcta 1140 aaagtcggag gaaggtgggg atgacgtcaa atcatcatgc cccttatgac ctgggctaca 1200 cacgtgctac aatgggcggt acaaagggct gcgaacccgc gagggggagc gaatcccaaa 1260 aagccgctct cagttcggat tgcaggctgc aactcgcctg catgaagccg gaatcgctag 1320 taatcgcgga tcagcatgcc gcggtgaata cgttcccggg ccttgtacac accgcccgtc 1380 acaccacgag agcttgcaac acccgaagtc ggtgaggtaa cccttacggg agccagccgc 1440 cgaaggtgat caagtg 1456

Claims

1. A compound microbial agent for sludge composting, characterized in that: Including Bacillus terrestris ( Geobacillus thermodenitrificans The *Bacillus geosporus* was deposited on March 29, 2021, at the China General Microbiological Culture Collection Center (CGMCC), at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, with accession number CGMCC No. 22088. Also includes Bacillus thermophilus (Ureaplasma thermophilus) Ureibacillus thermophilus The thermophilic urealyticus bacillus was deposited on March 29, 2021, at the China General Microbiological Culture Collection Center, located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, with accession number CGMCC No. 22086. Also includes Bacillus subtilis ( Bacillus subtilis The Bacillus subtilis strain was deposited on March 29, 2021, at the China General Microbiological Culture Collection Center (CGMCC), at No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing, with accession number CGMCC No. 22087.

2. The compound microbial agent for sludge composting according to claim 1, characterized in that: Based on viable count, the ratio of *Bacillus thermophilus* : *Bacillus subtilis* : *Bacillus thermophilus* = 1–3 : 1–2 : 2–3.

3. The compound microbial agent for sludge composting according to claim 1 or 2, characterized in that: The viable cell concentrations of *Bacillus thermophilus*, *Bacillus subtilis*, and *Bacillus thermophilus* were 1 × 10⁻⁶. 8 ~1×10 9 cfu / g.

4. The method for preparing the compound microbial agent for sludge composting according to any one of claims 1 to 3, characterized in that: Mix the microorganisms with compostable additives, dry them, and you will get the product.

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