Sludge waste variable-temperature fermentation process and application thereof

Abstract

The invention discloses a sludge waste variable-temperature fermentation process and application, accurate regulation and control of industrial sludge waste metabolism are realized through collocation of microbial inoculants, and an effective carbon closed loop is formed through the processes of high-temperature acid production, medium-temperature free fatty acid (FFAs) / glycerol production and low-temperature humification in cooperation with absorption and solidification of carbon dioxide. The method has the advantages that three-stage relay is formed by the thermophilic bacteria, the fat degrading bacteria and the humus synthesizing bacteria, efficient biotransformation of the industrial sludge waste is realized through the synergistic effect of the flora, cross inhibition does not exist among different flora, and smooth proceeding of the process is guaranteed. High-valued conversion of the product is realized through energy regeneration of isopropanol and soil improvement of humus, the economic value of the product is improved, cyclic utilization of resources is realized, and the method has good market prospects and environmental benefits.

Description

Technical Field

[0001] The invention relates to the technical field of sludge treatment, and in particular to a sludge waste temperature-variable fermentation process and application thereof. Background Art

[0002] Industrial sludge is a typical hazardous waste (HW08 category) in the fields of petrochemicals, machinery manufacturing, and oil refining. Its annual output exceeds 100 million tons and continues to grow at a rate of 8%-10%. Industrial sludge has complex components, including pollutants such as petroleum hydrocarbons (15%-40%), mineral oils (10%-30%), and polycyclic aromatic hydrocarbons. It is highly hydrophobic, difficult to degrade, and ecotoxic. If improperly disposed of, it may cause environmental risks such as groundwater pollution and soil degradation. However, the high organic matter content of this type of sludge also contains huge resource potential - petroleum hydrocarbons and mineral oils are essentially hydrocarbons. In theory, they can be converted into high-value products such as fatty acids through biotransformation, which can be used to cultivate soil probiotics and promote the dual goals of "pollution control" and "resource regeneration".

[0003] At present, the treatment of industrial sludge faces the dual dilemma of "difficult degradation" and "difficult value-added". Although traditional physical and chemical methods, such as pyrolysis and solvent extraction, can partially remove pollutants, they often come at the cost of high energy consumption or secondary pollution (such as solvent residues), and ignore the resource value of hydrocarbon components. Conventional biological methods, such as composting and anaerobic digestion, are in line with the green and low-carbon concept, but the degradation rate of long-chain hydrocarbons in the current biological treatment methods is low, the mineral oil encapsulation effect is obvious, and the added value of the final product is low. The utilization rate of carbon resources is insufficient and needs to be improved. Summary of the invention

[0004] To solve at least one of the above technical defects, the present invention provides the following technical solutions: The present invention discloses a sludge waste temperature-variable fermentation process, comprising the following steps: Step 1: Pre-treatment of sludge waste The sludge waste is subjected to ultrasonic activation treatment, and acid and / or alkali are added to react so that the pH value of the sludge waste after the ultrasonic activation treatment is 6-8.

[0005] Step 2: Temperature controlled fermentation High temperature fermentation treatment: add 0.1-0.5% of the functional bacteria group A by mass to the pretreated sludge mixture, raise the temperature to 60-65°C, and ferment in a microaerobic environment for 48-72 hours; wherein, the functional bacteria group A is obtained by mixing thermophilic Bacillus stearothermophilus BNCC338119, Pseudomonas aeruginosa BNCC360090 and Streptococcus thermophilus BNCC363554 in a volume ratio of 4-7:1-2:3-5.

[0006] Mesophilic fermentation treatment: The temperature of the sludge mixture after high-temperature fermentation treatment is reduced to 35 - 40 °C, and functional bacteria group B accounting for 0.1 - 0.5% of the mass of the sludge mixture is added for aerobic fermentation for 96 - 120 h; among them, Saccharomyces cerevisiae BNCC186741 and Propionibacterium jensenii BNCC194214 are mixed in a volume ratio of 6 - 8:1 - 3, and mesophilic lipase accounting for 10 - 20% of the total mass of the mixed bacterial liquid is added to obtain functional bacteria group B.

[0007] Low-temperature fermentation treatment: The sludge mixture after mesophilic fermentation treatment is cooled to 25 - 30 °C and mixed with wood chips in a volume ratio of 1.5 - 4:1, and functional bacteria agent C accounting for 1 - 2% of the mass of the sludge mixture is added for fermentation for 120 - 168 h to obtain a sludge fermentation product; among them, Pseudomonas putida BNCC338119, Bacillus subtilis with the preservation number CGMCC NO.26196, and Trichoderma longibrachiatum with the preservation number CGMCC.NO.40444 are mixed in a volume ratio of 1 - 4:2 - 6:4 - 9, and low-temperature lipase accounting for 20 - 30% of the total mass of the mixed bacterial liquid is added to obtain functional bacteria group C.

[0008] The principle is as follows: The cavitation effect of ultrasonic treatment can comprehensively activate sludge waste, and at the same time can partially remove pathogens in the sludge. Acids and alkalis can adjust the pH in the reaction and can also partially remove pathogens, etc., providing guarantee for subsequent inoculation of bacteria agents, fermentation, etc.

[0009] As Figure 1 shown, the core task in the high-temperature stage is to degrade long-chain petroleum hydrocarbons (C10 - C40) and small-molecule alcohols (such as isopropanol) through microorganisms. In this stage, it mainly relies on the action of bacteria such as Bacillus stearothermophilus and Pseudomonas aeruginosa. Bacillus stearothermophilus can tolerate high temperatures and secrete alkane monooxygenase (AlkB), which decomposes long-chain petroleum hydrocarbons (such as C10 - C40) and fatty acids through oxidation, while Pseudomonas aeruginosa can dissolve petroleum hydrocarbons through emulsification and assist in further degradation. Ester compounds in mineral oil are also decomposed into fatty acids and isopropanol by Streptococcus thermophilus BNCC363554 in this stage. Isopropanol can be extracted and recovered as a gas, and the purity can reach more than 85%, which is used for subsequent energy conversion. The temperature is controlled between 60 °C and 65 °C, and stepwise heating is ensured to keep microorganisms active within a suitable temperature range and promote the degradation efficiency. A micro-oxygen environment can maintain the growth and enzyme activity of microorganisms. The products of this stage are mainly medium- and short-chain fatty acids (such as acetic acid and propionic acid), which are supplied for use in the mesophilic fermentation stage.

[0010] The main task of the mesophilic fermentation stage is to process the medium- and short-chain fatty acids (such as free fatty acids from C2 to C18) produced in the thermophilic stage. Acidipropionibacterium jensenii oxidizes short-chain fatty acids (C2 - C6) into carbon dioxide to prevent excessive acidic substances from inhibiting the growth and metabolism of microorganisms. Triglycerides are jointly degraded and utilized by the mesophilic lipase LipA and Saccharomyces cerevisiae BNCC186741, and the product glycerol is completely retained as a carbon source raw material input in the low-temperature stage to maintain the metabolic activities of microorganisms and promote the smooth progress of subsequent reactions. The operating temperature in the mesophilic stage is controlled at 35°C to 40°C to ensure the optimal activity of the enzyme.

[0011] The core task of the low-temperature stage is to utilize glycerol to drive the degradation of FFAs (C16 - C18) and recalcitrant polycyclic aromatic hydrocarbons (PAHs, such as phenanthrene and pyrene), and promote the synthesis of humus through wood chips. In this stage, the low-temperature lipase (LipP) is mainly responsible for decomposing free fatty acids, while Pseudomonas putida degrades recalcitrant PAHs through dioxygenase, and uses glycerol as a co-metabolic carbon source to improve the degradation efficiency. At the same time, the wood chips provide lignin-like substances, and Bacillus subtilis and Trichoderma harzianum secrete lignin peroxidase (LiP) and laccase (Laccase) to cleave the wood chips to generate phenolic compounds, which react with FFAs derivatives to finally synthesize humic acid, which can significantly improve the structure and fertility of the soil.

[0012] Furthermore, first cultivate Bacillus stearothermophilus BNCC338119, Pseudomonas aeruginosa BNCC360090, and Streptococcus thermophilus BNCC363554 respectively to a bacterial liquid with a concentration of 3 - 9×10 10 cfu / ml, and then mix them according to the volume ratio to obtain functional bacterial group A.

[0013] First cultivate Saccharomyces cerevisiae BNCC186741 and Acidipropionibacterium jensenii BNCC194214 respectively to a bacterial liquid with a concentration of 2 - 8×10 10 cfu / ml, and the concentration of the mesophilic lipase used is 2 - 4×10 4 U / ml, and then mix them according to the volume ratio to obtain functional bacterial group B.

[0014] First cultivate Pseudomonas putida BNCC338119, Bacillus subtilis CGMCC.NO.26196, and Trichoderma harzianum preservation number CGMCC.NO.40444 respectively to a concentration of 1 - 6×10 9For the bacterial solution with a concentration of cfu / ml, the concentration of the low-temperature lipase used is 2 - 8×10 5 U / ml, and then they are mixed according to the volume ratio to obtain the functional bacterial group C.

[0015] Furthermore, before the ultrasonic activation treatment, adjust the water content of the sludge waste to 60 - 80%; During the ultrasonic activation treatment, the ultrasonic frequency is 20 - 25 kHz, the ultrasonic power is 300 - 500 W, the time is 10 - 20 min, and the treatment temperature is 25 - 30 °C, which can better comprehensively activate the sludge waste.

[0016] Furthermore, the acid and alkali in step one are boric acid and potassium hydroxide respectively. The addition amount of boric acid is 1 - 3% of the mass of the sludge waste, the addition amount of potassium hydroxide is 0.5 - 2% of the mass of the sludge waste, the reaction temperature is 25 - 30 °C, the stirring speed is 100 - 150 r / min, and the reaction time is 50 - 70 min. Control the quantity ratio and temperature, etc. to make the reaction complete gently and fully, and at the same time ensure that the pH value is within the predetermined range.

[0017] Furthermore, during the high-temperature fermentation treatment of temperature-controlled fermentation, the oxygen concentration is 0.5 - 1%, the stirring speed is 80 - 100 r / min, and the heating rate is 0.3 - 0.6 °C / min.

[0018] Furthermore, both the high-temperature fermentation treatment and the medium-temperature fermentation treatment are carried out in a fermentation tank. During the low-temperature fermentation treatment, it is separated from the fermentation tank and a pile body is established for fermentation. The fermentation temperature can be easily controlled through the fermentation tank.

[0019] Furthermore, the waste gas generated during the low-temperature fermentation treatment is absorbed by the waste gas collection device and solidified by calcium hydroxide absorption in the waste gas collection device. The important product at this stage is carbon dioxide. After being absorbed and solidified by Ca(OH)2, the conversion rate reaches more than 90%. Further carbon sequestration and pollutant degradation are realized. Through the comprehensive action of this stage, an effective carbon closed-loop is formed, the degradation and resource utilization of organic pollutants are completed, and at the same time, the economy and environmental benefits are improved.

[0020] For the hydrogen sulfide waste gas generated during the low-temperature fermentation treatment, it can be removed through an alkaline absorption tower and an ozone-hydrogenation UV photocatalytic reactor.

[0021] The present invention also discloses the application of the sludge fermentation product obtained by the above fermentation process in a soil conditioner.

[0022] If the water content of the fermentation product obtained by the above fermentation process is reduced to 10 - 30%, and then it is crushed into particles, the particles can be used to improve the soil. The reduction of the water content helps the particles to be stored stably for a long time and reduces the risk of mildew.

[0023] Advantages of the present invention compared with the prior art: 1. The present invention realizes precise regulation of the metabolism of industrial sludge waste through the combination of bacterial agents, and forms an effective carbon closed-loop through the processes of high-temperature acid production, medium-temperature free fatty acid (FFAs) / glycerol production, low-temperature humification, and the absorption and solidification of carbon dioxide, ensuring the maximization of resource utilization.

[0024] 2. The present invention forms a three-stage relay with thermophilic bacteria, fat-degrading bacteria, and humus-synthesizing bacteria, and realizes the efficient biological conversion of industrial sludge waste through the synergistic action of the bacterial communities. There is no cross-inhibition between different bacterial communities, ensuring the smooth progress of the process. Through the energy conversion of isopropanol and the soil improvement of humus, the high-value conversion of products is realized, the economic value of the products is increased, the recycling of resources is realized, and it has good market prospects and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a fermentation mechanism diagram. DETAILED DESCRIPTION OF THE INVENTION

[0026] The present invention will be further described below in conjunction with specific embodiments.

[0027] Bacillus subtilis ( Bacillus subtilis ) was deposited at the China General Microbiological Culture Collection Center (CGMCC) on December 14, 2022, with the deposit number: CGMCC.NO.26196, and the deposit address is No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing.

[0028] Trichoderma longibrachiatum ( Bacillus subtilis ) was deposited at the China General Microbiological Culture Collection Center (CGMCC) on December 14, 2022, with the deposit number: CGMCC.NO.40444, and the deposit address is No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing.

[0029] Bacillus stearothermophilus BNCC338119, Pseudomonas aeruginosa BNCC360090, Streptococcus thermophilus BNCC363554, Saccharomyces cerevisiae BNCC186741, Propionibacterium jensenii BNCC194214, and Pseudomonas putida BNCC338119 were all purchased from Beina Biotechnology. The medium-temperature lipase model is lipase A, lysosomal acid type, gene ID3988, and the low-temperature lipase model is LIP98.

[0030] Among them, Bacillus stearothermophilus BNCC338119, Pseudomonas aeruginosa BNCC360090, and Streptococcus thermophilus BNCC363554 were cultured in a selective medium A: peptone 10.0 g / L, beef powder 3.0 g / L, sodium chloride 5.0 g / L, agar 15.0 g / L, pH 7.3 ± 0.1, at a temperature of 46°C until the concentration reached 4.48×10 10 cfu / ml, 6.11×10 10 cfu / ml, 4.21×10 10 cfu / ml of bacterial suspensions.

[0031] Saccharomyces cerevisiae BNCC186741 and Propionibacterium jensenii BNCC194214 were cultured in a selective medium B: yeast extract powder 3.0 g / L, malt extract 3.0 g / L, glucose 10.0 g / L, casein peptone 5.0 g / L, agar 20.0 g / L, pH 6.2 ± 0.2, at a temperature of 30°C until the concentration reached 4.55×10 10 cfu / ml, 5.53×10 10 cfu / ml of bacterial suspensions.

[0032] Pseudomonas putida BNCC338119 was cultured in a selective medium C: peptone 10.0 g / L, beef powder 3.0 g / L, sodium chloride 5.0 g / L, agar 15.0 g / L, pH 7.3 ± 0.1, at a temperature of 25°C until the concentration reached 5.48×10 9 cfu / ml of bacterial suspension.

[0033] Bacillus subtilis CGMCC.NO.26196 was cultured in a special fermentation medium D: sodium carboxymethyl cellulose 20 g / L, ammonium sulfate 2 g / L, dipotassium hydrogen phosphate 1 g / L, magnesium sulfate 0.5 g / L, calcium chloride 1 g / L, manganese sulfate 0.05 g / L, ferrous sulfate 0.05 g / L, pH 7.0, at a temperature of 25°C until the concentration reached 2.36×10 9 cfu / ml of bacterial suspension.

[0034] Trichoderma longibrachiatum CGMCC.NO.40444 was cultured in a special fermentation medium E: potato leaching solution 200 g / L, dipotassium hydrogen phosphate 2 g / L, sodium carboxymethyl cellulose 20 g / L, guaiacol 0.1 g / L, pH 6.0, at a temperature of 25°C until the concentration reached 3.41×10 9 cfu / ml of bacterial suspension.

[0035] The concentration of mesophilic lipase was 3×10 4 cfu / ml, and the concentration of low-temperature lipase was 6×10 5 cfu / ml.

[0036] The components of the industrial sludge waste to be treated are as follows by mass: petroleum hydrocarbons 35%, mineral oil substances 26%, polycyclic aromatic hydrocarbons 10%, and the balance is water.

[0037] Example 1 A variable-temperature fermentation process for sludge waste, comprising the following steps: Step 1. Pretreat the sludge waste Adjust the water content of the above industrial sludge waste to 70%, and perform ultrasonic activation treatment on the adjusted sludge waste with a probe-type ultrasonic emission device at an ultrasonic frequency of 22 kHz, an ultrasonic power of 400 W, and an ultrasonic time of 15 min.

[0038] Add boric acid to the ultrasonically activated sludge waste, where the boric acid accounts for 1.5% of the mass of the adjusted sludge waste, and add the corresponding amount of potassium hydroxide to ensure that the pH value of the sludge waste is 7.0, the reaction temperature is 25 °C, the reaction time is 60 min, and the rotation speed is 120 r / min.

[0039] Step 2. Temperature-controlled fermentation Add the mixture of the pretreated industrial sludge waste to the fermentation tank.

[0040] High-temperature fermentation treatment: Add functional bacterial group A accounting for 0.2% of the mass of the pretreated sludge mixture, heat it to 65 °C at a rate of 0.5 °C / min, under a micro-aerobic environment (oxygen concentration of 0.6%), with a stirring speed of 90 r / min and a time of 50 h. During this process, detect the concentration of isopropanol with an on-line gas chromatograph. When the concentration ≥ 5 g / L, recover isopropanol with a stripping system and a secondary condenser, and the purity ≥ 85%.

[0041] The above-cultured Bacillus stearothermophilus BNCC338119, Pseudomonas aeruginosa BNCC360090, and Streptococcus thermophilus BNCC363554 are mixed in a volume (liquid) ratio of 5:1:4 to obtain functional bacterial group A.

[0042] Medium-temperature fermentation treatment: Cool the temperature of the sludge after high-temperature fermentation treatment to 36 °C, add functional bacterial group B accounting for 0.1% of the mass of the sludge for aerobic fermentation (oxygen concentration of 4%), with a time of 100 h and a stirring speed of 75 r / min.

[0043] The above-cultured Saccharomyces cerevisiae BNCC186741 and Propionibacterium jensenii BNCC194214 are mixed in a volume (liquid) ratio of 7:2, and a medium-temperature lipase accounting for 12% of the total bacterial liquid mass of Saccharomyces cerevisiae BNCC186741 and Propionibacterium jensenii BNCC194214 is added to obtain functional bacterial group B.

[0044] Low-temperature fermentation treatment: Take out the sludge mixture after medium-temperature fermentation treatment from the fermentation tank. Mix the taken-out sludge waste with wood chips (straw particles) at a volume ratio of 2:1, and add functional bacterium agent C accounting for 1.5% of its mass to the mixture. Build a pile body with a height of 1.5 m for the total mixture and ferment at 25°C for 5 days, turning the pile manually once a day. Most of the exhaust gas generated during the low-temperature fermentation process is carbon dioxide. Absorb and solidify the carbon dioxide with calcium hydroxide in the exhaust gas recovery device. First, pass the hydrogen sulfide in the exhaust gas through an alkaline absorption tower (NaOH solution, concentration 7%), and H2S reacts with NaOH to form Na2S (removal rate ≥ 80%). Subsequently, enter the ozone-enhanced UV photocatalytic reactor (ozone dosage 15 g / m 3 , 254 nm ultraviolet-excited TiO2 / activated carbon catalyst), and simultaneously oxidize the residual H2S and benzene series into SO4 2- and CO2. The total removal rate of H2S is ≥ 99%, and the emission concentration is ≤ 0.06 mg / m 3 .

[0045] The above-cultured Pseudomonas putida BNCC338119, Bacillus subtilis with the preservation number of CGMCC NO.26196, and Trichoderma longibrachiatum with the preservation number of CGMCC.NO.40444 are mixed at a volume (liquid) ratio of 2:3:5, and low-temperature lipase accounting for 25% of the total mass of the mixed bacterial solution is added to obtain functional bacterium group C.

[0046] To more intuitively reflect the effect of this bacterium agent combination, add control cases as follows: Treatment 1: The difference from Example 1 is that no bacterium agent or auxiliary material is added in this example.

[0047] Treatment 2: The same as Example 1.

[0048] Treatment 3: The difference from Example 1 is that functional bacterium group A is not added during the high-temperature fermentation stage.

[0049] Treatment 4: The difference from Example 1 is that functional bacterium group B is not added during the medium-temperature fermentation stage.

[0050] Treatment 5: The difference from Example 1 is that functional bacterium group C is not added during the low-temperature fermentation stage.

[0051] Treatment 6: The difference from Example 1 is that during the low-temperature fermentation stage, Thermophilic Bacillus lipolyticus BNCC.338119 is not added to functional bacterium group A, and a commercially available Thermophilic Bacillus lipolyticus is used for replacement.

[0052] Treatment 7: The difference from Example 1 is that during the low-temperature fermentation stage, Trichoderma longibrachiatum with the preservation number CGMCC.NO.40444 is not added to functional bacterial group C, and a commercially available Trichoderma longibrachiatum is used as a replacement.

[0053] Treatment 8: The difference from Example 1 is that during the low-temperature fermentation stage, functional bacterial group C is not added, and a straw composting inoculant sold by Shandong Sapphire Company is added.

[0054] During the three stages of fermentation, the fermentation target treatment substances and products are measured respectively. After the end of the third stage, the concentrations of isopropanol and hydrogen sulfide in the exhaust gas are counted. The test results are shown in Table 1.

[0055] Table 1

[0056] For each stage of treatment, there are significant differences with the addition of the inoculant. Treatment 2 achieves the best effect or one of the best effects in each stage.

[0057] At the high-temperature stage, with the addition of functional bacterial group A, there were no significant differences in the remaining amounts of petroleum hydrocarbons (C10-C40), mineral oil, and the contents of medium- and short-chain fatty acids in Treatments 2, 4, 5, 7, and 8, but they were significantly better than those in Treatments 1, 3, and 6. The reason is that: at the high-temperature stage, which is the first stage of fermentation, Treatments 2, 4, 5, 7, and 8 can be regarded as the same treatment. The addition of functional bacterial group A significantly enhanced the degradation of petroleum hydrocarbons (C10-C40) and mineral oil, and promoted the generation of medium- and short-chain fatty acids. In terms of the remaining amounts of petroleum hydrocarbons (C10-C40) and mineral oil, the order of significance was: Treatments 1, 3, and 6, which not only indicates the indispensability of the overall functional bacterial group A, but also shows that the replacement of Bacillus stearothermophilus (BNCC.338119) reduced the degradation of petroleum hydrocarbons (C10-C40). Comparing Treatments 1, 3, and 6 with Treatment 2, the replacement of Bacillus stearothermophilus (BNCC.338119) had a greater impact on the remaining amount of petroleum hydrocarbons (C10-C40), and a smaller impact on the remaining amounts of mineral oil and the contents of medium- and short-chain fatty acids. This is because Streptococcus thermophilus (BNCC363554), which is used for the degradation of ester compounds in mineral oil, was not changed, which also reflects the specific functionality of each component in functional bacterial group A. At the medium-temperature stage, with the addition of functional bacterial group B, there were no significant differences in the remaining amounts of medium- and short-chain fatty acids, triglyceride, and free fatty acid contents in Treatments 2, 5, 7, and 8, but they were significantly better than those in Treatments 1, 3, and 4. The reason is that: at the medium-temperature stage, which is the second stage of fermentation, Treatments 2, 5, 7, and 8 can be regarded as the same treatment. The remaining amount of medium- and short-chain fatty acids in Treatment 6 was significantly lower than that in Treatment 2 but significantly higher than that in Treatment 1, and its decomposition process at the high-temperature stage was delayed. At the same time, even though Treatment 3 lacked the promoting effect of functional bacterial group A at the high-temperature stage, the remaining amounts of medium- and short-chain fatty acids and triglycerides in Treatment 3 were significantly lower than those in Treatments 1 and 4, which proves that the addition of functional bacterial group B has a significant stage-specific function at the medium-temperature stage. At the low-temperature stage, with the addition of functional bacterial group C, there were no significant differences in the remaining amounts of refractory mineral oil (polycyclic aromatic hydrocarbons) in Treatments 2, 6, and 8, but they were significantly better than those in other treatment groups. The low-temperature stage is the last stage of fermentation. Treatments 3, 4, and 5 showed significant differences in the remaining amounts of refractory mineral oil (polycyclic aromatic hydrocarbons) and free fatty acids due to the lack of corresponding functional bacterial group addition in each stage. However, the remaining amount of refractory mineral oil (polycyclic aromatic hydrocarbons) and the remaining amount of free fatty acids in Treatment 5 were significantly higher than those in Treatments 3 and 4, and the humic acid content was significantly lower than that in Treatments 3 and 4, which proves that the addition of functional bacterial group C has a significant stage-specific function in the degradation of refractory mineral oil (polycyclic aromatic hydrocarbons) and free fatty acids and the generation of humus at the low-temperature stage.The residual amount of free fatty acids in Treatment 7 was significantly lower than that in Treatments 1 and 5, but significantly higher than that in Treatment 2; the humus content in Treatment 7 was significantly higher than that in Treatment 1, showed no significant difference from that in Treatment 5, but was significantly lower than that in Treatment 2. This indicates that the replacement of Trichoderma longiflorum (deposit number CGMCC.NO.40444) reduced the conversion efficiency of the residual free fatty acids into humus; meanwhile, the humus content in Treatment 8 was lower than that in Treatment Group 2, all of which proved that whether it was the replacement of Trichoderma longiflorum (deposit number CGMCC.NO.40444) or the replacement of functional bacterium C in the functional bacterium group, it would hinder the metabolite conversion process. Bacillus subtilis (CGMCC NO.26196) and Trichoderma longiflorum (deposit number CGMCC.NO.40444) are efficient and irreplaceable for the production of humus.

[0058] In terms of waste gas recovery, there were no significant differences in the isopropanol recovery amount and recovery rate among Treatments 2, 4, 5, 7, and 8, and they were significantly better than Treatments 1, 3, and 6, further confirming that the production of isopropanol occurred in the high-temperature stage and was related to the action of functional bacterium group A. There were no significant differences in the H2S recovery amount among Treatments 2, 5, 7, and 8, and they were significantly better than Treatments 1, 3, 4, and 6, which proved that the production of H2S occurred in the high-temperature and medium-temperature stages and was directly affected by functional bacterium group A and functional bacterium group B.

[0059] Dry the sludge fermentation products of the above treatment groups to reduce the water content to 20%, crush the fermentation products into particles, which are soil conditioners, and conduct planting tests with pakchoi as the object. The soil conditioner is mixed with conventional soil at a ratio of 1:1. The seed germination rate of pakchoi, the nutrient performance, and the biological safety of the soil conditioner are shown in Table 2.

[0060] Table 2

[0061] Among them, the seed germination rate is the germination rate in 7 days. It can be seen from Table 2 that Treatment 2 is significantly better than other products in terms of nutrient content, humic acid content, acidity and alkalinity, etc., and has the ability to supply nutrients. From the perspective of plant effects, the germination rate of Treatment 7 showed no significant difference from that of Treatment 2, but the polycyclic aromatic hydrocarbon residue content was relatively high, which might cause inhibition of root growth. The degradation effect of petroleum hydrocarbons in Treatment 8 was poor (200 - 250 mg / kg).

[0062] Dry the fermentation products of each of the above treatment groups to reduce the moisture content to 20%, and crush the fermentation products into particles, namely soil conditioners. Conduct planting tests with rice as the object. Mix the soil conditioner with the soil in the medium- and low-yield yellow soil fields in Jinhua City, Zhejiang Province at a ratio of 1:1, and additionally set a background group without adding the soil conditioner. Measure its relevant indicators as the background value. After 30 days of planting, take soil samples and rice seedlings to measure the indicators, as shown in Table 3.

[0063] Table 3

[0064] As can be seen from Table 3, the soil in Treatment 2 is significantly superior to other products in terms of physical properties, nutrient content, organic matter content, acidity and alkalinity, and plant growth conditions. It can effectively improve the physical properties of the soil, increase the nutrient supply, and correspondingly enhance the ability to increase rice yield. From the perspective of plant effects, the germination rate of Treatment 7 has no significant difference from that of Treatment 2, but the residual amounts of petroleum hydrocarbons and polycyclic aromatic hydrocarbons are relatively high, resulting in inhibition of root growth. The effect of Treatment 8 on improving physical properties is not obvious, and the effect of providing nutrients is medium, and the effect on promoting the growth of the final crop is also at a medium level. Therefore, the sludge fermentation products obtained by the fermentation process of the present invention can be applied to soil conditioners.

[0065] The above is only the preferred implementation mode of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions falling within the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for those of ordinary skill in the art in this technical field, several improvements and refinements made without departing from the principle of the present invention should also be regarded as within the protection scope of the present invention.

Claims

1. A variable-temperature fermentation process for sludge waste, characterized in that, It includes the following steps: Step 1: Pretreat the sludge waste Perform ultrasonic activation treatment on the sludge waste, add acid and / or alkali for reaction to make the pH of the sludge waste after ultrasonic activation treatment be 6 - 8; Step 2: Temperature-controlled fermentation High-temperature fermentation treatment: Add functional bacterial group A accounting for 0.1 - 0.5 wt% of the sludge mixture in Step 1, heat up to 60 - 65 °C, ferment in a micro-oxygen environment for 48 - 72 h; among them, Functional bacterial group A is obtained by mixing Bacillus stearothermophilus BNCC338119, Pseudomonas aeruginosa BNCC360090 and Streptococcus thermophilus BNCC363554 according to a volume ratio of 4 - 7:1 - 2:3 - 5; Mesophilic fermentation treatment: Cool the temperature of the sludge after high-temperature fermentation treatment to 35 - 40 °C, add functional bacterial group B accounting for 0.1 - 0.5 wt% of the sludge mixture for aerobic fermentation, and the fermentation time is 96 - 120 h; among them, functional bacterial group B is obtained by mixing Saccharomyces cerevisiae BNCC186741 and Propionibacterium jensenii BNCC194214 according to a volume ratio of 6 - 8:1 - 3, and adding mesophilic lipase accounting for 10 - 20 wt% of the total bacterial liquid after mixing; Low-temperature fermentation treatment: Cool the sludge mixture after mesophilic fermentation treatment to 25 - 30 °C, mix it with wood chips according to a volume ratio of 1.5 - 4:1, add functional bactericide C accounting for 1 - 2 wt% of the sludge mixture for fermentation for 120 - 168 h to obtain a sludge fermentation product; among them, functional bacterial group C is obtained by mixing Pseudomonas putida BNCC338119, Bacillus subtilis with the preservation number of CGMCC NO.26196 and Trichoderma longibrachiatum with the preservation number of CGMCC.NO.40444 according to a volume ratio of 1 - 4:2 - 6:4 - 9, and adding low-temperature lipase accounting for 20 - 30 wt% of the total bacterial liquid after mixing; 2. The temperature-variable fermentation process for sludge waste as described in claim 1, wherein: First, Bacillus stearothermophilus BNCC338119, Pseudomonas aeruginosa BNCC360090, and Streptococcus thermophilus BNCC363554 were respectively cultured to a bacterial liquid with a concentration of 3-9×10 10 cfu / ml, and then mixed to obtain functional bacteria group A; First, Saccharomyces cerevisiae BNCC186741 and Propionibacterium jensenii BNCC194214 were cultured to a bacterial liquid with a concentration of 2 - 8×10 10 cfu / ml, and the concentration of mesophilic lipase was 2 - 4×10 4 U / ml, and then they were mixed to obtain functional bacteria group B; Pseudomonas putida BNCC338119, Bacillus subtilis CGMCC.NO.26196, and Trichoderma longibrachiatum with the preservation number CGMCC.NO.40444 are respectively cultured until the concentration of the bacterial liquid reaches 1-6×10 9 cfu / ml, the concentration of the cold-adapted lipase is 2-8×10 5 U / ml, and then they are mixed to obtain the functional bacteria group C.

3. The variable-temperature fermentation process for sludge waste as described in claim 1, characterized in that: Before ultrasonic activation treatment, adjust the water content of the sludge waste to 60 - 80%; During ultrasonic activation treatment, the ultrasonic frequency is 20 - 25 kHz, the ultrasonic power is 300 - 500 W, the time is 10 - 20 min, and the treatment temperature is 25 - 30 °C.

4. The variable-temperature fermentation process for sludge waste as described in claim 1, characterized in that: In Step 1, the acid and alkali are boric acid and potassium hydroxide respectively. The addition amount of boric acid is 1 - 3% of the mass of the sludge waste, the addition amount of potassium hydroxide is 0.5 - 2% of the mass of the sludge waste, the reaction temperature is 25 - 30 °C, the stirring speed is 100 - 150 r / min, and the reaction time is 50 - 70 min.

5. The temperature-variable fermentation process for sludge waste as described in claim 1, characterized in that: In the high-temperature fermentation treatment of temperature-controlled fermentation, the oxygen concentration is 0.5 - 1%, the stirring speed is 80 - 100 r / min, and the heating rate is 0.3 - 0.6 °C / min.

6. The variable-temperature fermentation process for sludge waste as claimed in claim 1, wherein: In Step 2, the high-temperature fermentation treatment and mesophilic fermentation treatment are both carried out in a fermentation tank. During low-temperature fermentation treatment, it is separated from the fermentation tank and a pile body is established for fermentation.

7. A variable temperature fermentation process for sludge waste, characterized in that: The waste gas generated during low-temperature fermentation treatment in Step 2 is absorbed by a waste gas collection device and solidified by absorption with calcium hydroxide in the waste gas collection device.

8. Application of the sludge fermentation product obtained by the fermentation process according to any one of claims 1 - 7 in a soil conditioner.

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