Method for promoting anaerobic methane production of sludge through signal molecule reinforced biochar

Abstract

The invention belongs to the technical field of sludge treatment and recycling, and particularly relates to a method for promoting anaerobic methane production of sludge through signal molecule reinforced biochar. Comprising the following steps: cleaning, drying, grinding and screening a biochar material to obtain biochar particles; carrying out sedimentation, sieving and thermal pretreatment on the residual sludge to obtain pretreated sludge; mixing the pretreated sludge with the inoculated sludge to obtain mixed sludge; the method comprises the following steps: adding charcoal particles, signal molecules and mixed sludge into an anaerobic reactor, carrying out nitrogen aeration on the anaerobic reactor, sealing the anaerobic reactor in a water bath constant-temperature oscillator, and carrying out methane production until no methane is generated in the anaerobic reactor; the signal molecule is AHLs; the invention solves the problems of low electron transfer rate, long lag time of the anaerobic digestion system and the like in the traditional anaerobic digestion system in the prior art.

Description

Technical Field

[0001] The invention belongs to the technical field of sludge treatment and resource utilization, and relates to a method for promoting anaerobic methanogenesis of sludge by strengthening biochar through signal molecules. Background Art

[0002] The residual sludge produced by the sewage treatment plant contains a large amount of organic matter, such as polysaccharides, proteins, humic acid, etc., accounting for more than 60% of the dry weight, and also contains rich resources such as nitrogen and phosphorus, which can be used as a carrier of energy and resources. Compared with other sludge treatment and disposal technologies, anaerobic digestion technology can decompose organic matter in sludge, reduce the content of volatile solids, and kill parasite eggs and pathogenic bacteria. It not only achieves the purpose of sludge reduction, stabilization and harmlessness, but also can recycle energy and resources, such as methane, hydrogen and short-chain fatty acids. Therefore, anaerobic digestion technology has greater economic, environmental and social benefits, meets the sustainable development needs of residual sludge treatment and disposal, and is expected to achieve green and low-energy operation of sewage treatment plants, thereby promoting the high-quality development of the sewage treatment industry.

[0003] Common sludge treatment technologies include concentration and dehydration, thermal drying, aerobic fermentation and anaerobic digestion. Among them, anaerobic digestion technology has important application prospects in the field of sludge treatment due to its advantages such as energy recovery and low operating costs. This technology converts organic matter into short-chain fatty acids, hydrogen and methane through the action of microorganisms, achieving harmful substance removal and energy recovery. However, traditional anaerobic digestion processes have many limitations, such as low digestion efficiency, insufficient reduction of volatile solids and low methane production.

[0004] The functional microbial flora of the anaerobic digestion system mainly includes hydrolytic fermentation bacteria, homoacetogenic bacteria, hydrogen-producing acetogenic bacteria and methanogenic bacteria. In the traditional anaerobic digestion system, the information exchange efficiency between microorganisms is low and the electron transfer rate is limited, especially when hydrogen and formic acid are used as electron transfer carriers, the diffusion efficiency is low and the distance between cells is strict, which further limits the improvement of anaerobic digestion efficiency.

[0005] In recent years, in order to overcome the shortcomings of traditional anaerobic digestion systems, researchers have begun to try to improve the efficiency of information exchange and electron transfer between microorganisms through exogenous additives (such as biochar). Biochar has been proven to promote the attachment and immobilization of microorganisms and enhance interspecies electron transfer due to its good conductivity and good physical and chemical properties, thereby improving the efficiency of anaerobic digestion. In addition, quorum sensing, as a key mechanism for information transfer between microorganisms, plays an important role in anaerobic digestion systems by regulating community gene expression.

[0006] Biochar can provide suitable conditions for the attachment and growth of microorganisms in anaerobic digestion, improve the stability of microbial immobilization, and reduce the inhibitory effect of inhibitors through the adsorption process. The porous structure of biochar not only helps to adsorb potentially harmful substances such as heavy metals, organic acids and ammonia in the anaerobic digestion system, but also provides a conductive channel for the electron transfer process, thereby promoting the synergistic metabolic activities among microbial populations. Studies have shown that adding biochar to the anaerobic system can shorten the lag time of methane production, improve the efficiency of methane production, and enhance the stability of the anaerobic digestion system.

[0007] As the core mechanism of microbial information transmission, quorum sensing regulates microbial behavior through signal molecules, including biofilm formation, metabolic activity, and optimization of microbial communities. When the cell density reaches a certain threshold, signal molecules will activate the expression of related genes, thereby improving the metabolic efficiency of microorganisms and system stability. Studies have shown that exogenously added quorum sensing signal molecules (such as acyl-homoserine lactone signal molecules (AHLs)) can significantly improve the metabolic efficiency of microorganisms, accelerate the formation of biofilms in anaerobic systems, optimize the structure of microbial communities, enhance the electron transfer rate, and increase methane production.

[0008] Although biochar has the potential to promote the methane production efficiency of anaerobic digestion of sludge, its promotion of information exchange between microbial species is extremely limited, and it has no selectivity for the enrichment of functional microorganisms. It is urgent to invent a feasible means or technology to improve the directional enrichment of functional microorganisms by biochar, thereby enhancing the biochar-mediated interspecies symbiosis of microorganisms, and ultimately improving the efficiency and rate of conversion of sludge organic matter into methane. Summary of the invention

[0009] In view of the problems existing in the prior art, the present invention provides a method for promoting anaerobic methanogenesis in sludge by enhancing biochar through signal molecules, which solves the problems of low electron transfer rate and long lag time of anaerobic digestion system in traditional anaerobic digestion system in the prior art.

[0010] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides a method for promoting anaerobic methanogenesis of sludge by strengthening biochar through signal molecules, comprising: The biochar material is cleaned, dried, ground and sieved to obtain biochar particles; The residual sludge is subjected to sedimentation, screening and thermal pretreatment to obtain pretreated sludge; the pretreated sludge and the inoculated sludge are mixed to obtain mixed sludge; The biochar particles, signal molecules and mixed sludge are added to the anaerobic reactor, and the anaerobic reactor is sealed and placed in a water bath constant temperature oscillator after nitrogen aeration to produce methane until no more methane is produced in the anaerobic reactor; Wherein, the signal molecule is AHLs.

[0011] Preferably, the mass ratio of the signal molecules, the biochar particles and the volatile suspended solids in the mixed sludge is 0.000124:1:1.

[0012] Preferably, the method for preparing the biochar material is: pyrolyzing the biomass material under anaerobic conditions at 400-600°C for 2-4 h to obtain the biochar material.

[0013] Preferably, the biochar material is dried at a temperature not higher than 80° C. for not less than 24 hours.

[0014] Preferably, the particle size of the biochar particles is 0.1 to 0.2 mm.

[0015] Preferably, the residual sludge settling time is not less than 24 h.

[0016] Preferably, the excess sludge is sieved using a 0.45 mm sieve.

[0017] Preferably, the volume ratio of the inoculated sludge to the pretreated sludge is 1:4.

[0018] Preferably, the heat pretreatment is performed at 80°C for no less than 30 min.

[0019] Preferably, the shaking speed of the water bath constant temperature oscillator is 120-130 rpm and the temperature is 35±1°C.

[0020] Compared with the prior art, the present invention has the following beneficial effects: Compared with the traditional anaerobic methanogenesis technology, the present invention introduces the signal molecule AHLs into the anaerobic digestion system of sludge to strengthen the inter-species mutualism between microorganisms mediated by biochar, significantly improves the information transmission ability and electron transfer rate and efficiency between microbial populations, and achieves a more efficient methane generation rate and methane production as well as a more stable anaerobic digestion system. Specifically, the present invention optimizes the synergistic effect of biochar and signal molecule AHLs, strengthens the role of biochar in promoting the DIET process, accelerates the information exchange effect between different bacterial communities, significantly increases methane production and improves the methane generation rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 It is a line graph of the methane accumulation of each group in Example 1 of the present invention and the comparative example; Figure 2 It is a line graph of the methane generation rate of each group of Example 1 of the present invention and the comparative example. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0024] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0025] In this article, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions).

[0026] In this document, unless otherwise specified, “includes,” “including,” “contains,” “has,” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0027] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0028] The present invention is further described in detail below in conjunction with the accompanying drawings: The present invention provides a method for promoting anaerobic methanogenesis of sludge by strengthening biochar through signal molecules, comprising: The biochar material is cleaned, dried, ground and sieved to obtain biochar particles; The residual sludge is subjected to sedimentation, screening and thermal pretreatment to obtain pretreated sludge; the pretreated sludge and the inoculated sludge are mixed to obtain mixed sludge; Biochar particles, signal molecules AHLs and mixed sludge are added to the anaerobic reactor, which is sealed and placed in a water bath constant temperature oscillator after nitrogen aeration to produce methane until no more methane is produced in the anaerobic reactor. Under anaerobic conditions, anaerobic microorganisms produce methane by decomposing complex organic matter (such as organic matter in mixed sludge).

[0029] Among them, residual sludge refers to the solid matter remaining after the pollutants in sewage are removed by physical, chemical or biological means during the sewage treatment process. These solid substances include microorganisms, dead bacteria, precipitated inorganic matter, undegraded organic matter, etc., which eventually exist in the form of sludge. Inoculated sludge refers to the sludge with a certain microbial population added to the sewage system in order to start or enhance the degradation function of microorganisms during the sewage treatment process, especially in the biological treatment stage (such as activated sludge method). Signal molecules AHLs include C6-HSL, C8-HSL and C 10 -HSL, etc., signal molecules AHLs are key molecules for bacterial quorum sensing, regulating bacterial group behavior, helping bacteria adapt to the environment and coordinating complex biological processes in the group. Biochar materials are fruit wood, bark, straw or stalks, etc.

[0030] The further optimized solution specifically includes the following steps: The biomass material is pyrolyzed for 2-4 h at 400-600°C in the absence of oxygen to obtain a biochar material; the biochar is repeatedly washed with deionized water until soluble impurities (such as soluble salts, incompletely carbonized small molecular compounds, etc.) on its surface are removed; the washed biochar material is dried at a temperature not higher than 80°C for not less than 24 h; after drying, biochar particles with a particle size of 0.1-0.2 mm are obtained by screening; the present invention generates biochar material (carbon-rich solid matter), volatile gas and liquid product by decomposing organic components in the biomass material at 400-600°C in the absence of oxygen; the soluble ions on the surface of the biochar material, including soluble salts and harmful ions, such as sulfur ions and chloride ions, can be removed by washing the biochar material; the particle size distribution of the biochar material can be adjusted by grinding and screening the biochar material, so that harmful substances in the mixed sludge can be more effectively adsorbed and the influence on the microbial activity of the sludge anaerobic digestion system can be reduced.

[0031] The residual sludge is naturally settled for no less than 24 hours, and the settled residual sludge is sieved with a 0.45 mm sieve to remove gravel; the sieved residual sludge is heat pretreated at 80 ° C for no less than 30 minutes to obtain pretreated sludge; the inoculated sludge and the pretreated sludge are mixed in a volume ratio of 1:4 to obtain mixed sludge. The residual sludge of the present invention can remove large particles and some difficult-to-degrade organic matter in the residual sludge through sedimentation, sieving and heat pretreatment, so that the residual sludge is more uniform and its biodegradability is improved; at the same time, the heat pretreatment can destroy the structure of the residual sludge, release more soluble organic matter, and create more favorable substrate conditions for subsequent methane production. The inoculated sludge is rich in anaerobic functional microorganisms that can degrade organic matter. After mixing with the pretreated sludge, it can quickly adapt to the environment and begin to degrade organic matter in the sludge, and finally convert the organic matter into methane.

[0032] The signal molecule AHLs, biochar particles and volatile suspended solids in the mixed sludge are added to the anaerobic reactor in a mass ratio of 0.000124:1:1. After the anaerobic reactor is aerated with nitrogen for no less than 5 minutes, the anaerobic reactor is sealed and placed in a water bath constant temperature oscillator. The shaking speed of the water bath constant temperature oscillator is 120-130 rpm and the temperature is 35±1°C to produce methane until no methane is generated in the anaerobic reactor. The signal molecule AHLs, biochar particles and mixed sludge are mixed, which has a significant promoting effect on the anaerobic digestion process of the sludge and improves the methane production efficiency. Signal molecules AHLs and biochar can promote the utilization of dissolved polysaccharides and proteins by microorganisms during anaerobic digestion, and promote the accumulation of small molecular organic acids, providing more easily utilized substrates for subsequent stages, indicating that signal molecules AHLs and biochar play a synergistic role in the hydrolysis and acidification process. In addition, the use of pure substances as substrates in the anaerobic digestion system also confirms the synergistic promotion of signal molecules AHLs and biochar in the methanogenesis stage. Mechanistic analysis shows that signal molecules AHLs significantly improve the accumulation and consumption efficiency of acetic acid during biochar-mediated anaerobic digestion of sludge, and at the same time promote the evolution of mixed-trophic methanogens by directional regulation of the structural composition of methanogenic bacteria, and enhance the mutualistic metabolic efficiency between microbial species. In addition, higher coenzyme F420 activity indicated that the signal molecule AHLs promoted the hydrogenotrophic methanogenesis pathway of the biochar-mediated anaerobic digestion system of sludge, while higher cytochrome c activity reflected that the signal molecule AHLs could also promote the biochar-mediated direct interspecies electron transfer process of microorganisms, that is, promote the direct interspecies electron transfer (DIET) methanogenesis pathway of microorganisms.

[0033] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0034] The following examples use conventional instruments and equipment in the art. The experimental methods in the following examples where specific conditions are not specified are usually carried out under conventional conditions or under conditions recommended by the manufacturer. The various raw materials used in the following examples are conventional commercial products unless otherwise specified, and their specifications are conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" means weight percentage, "part" means weight part, and ratio means weight ratio.

[0035] Example 1 The fruit wood was pyrolyzed at 500 °C for 2 h in the absence of oxygen to obtain biochar material; the biochar material was repeatedly washed with deionized water until the soluble ions on its surface were removed; the washed biochar material was dried at 70 °C for 26 h; after drying, the biochar particles with a particle size of 0.2 mm were obtained by sieving; The residual sludge was naturally settled for 26 h, and the settled residual sludge was sieved with a 0.45 mm sieve to remove gravel and large particles of impurities; the sieved residual sludge was heat pretreated at 80 °C for 40 min to obtain pretreated sludge; the inoculated sludge and the pretreated sludge were mixed in a volume ratio of 1:4 to obtain mixed sludge; The signal molecule C6-HSL, biochar particles and volatile suspended solids in the mixed sludge were added to the anaerobic reactor at a mass ratio of 0.000124:1:1. After the anaerobic reactor was aerated with nitrogen for 7 min, the anaerobic reactor was sealed and placed in a water bath constant temperature oscillator with a shaking speed of 130 rpm and a temperature of 35 ℃ for methane production until no more methane was produced in the anaerobic reactor. The cumulative methane production was 154.7 mL / gVSS, and the maximum daily methane production was 25.3 mL.

[0036] Example 2 The bark was pyrolyzed at 600 °C for 3 h in the absence of oxygen to obtain biochar material; the biochar was repeatedly washed with deionized water until the soluble ions on its surface were removed; the washed biochar material was dried at 75 °C for 25 h; after drying, the biochar particles with a particle size of 0.15 mm were obtained by sieving; The residual sludge was naturally settled for 25 h, and the settled residual sludge was sieved with a 0.45 mm sieve to remove gravel and large particles of impurities; the sieved residual sludge was heat pretreated at 80 °C for 35 min to obtain pretreated sludge; the inoculated sludge and the pretreated sludge were mixed in a volume ratio of 1:4 to obtain mixed sludge; The signal molecule C6-HSL, biochar particles and volatile suspended solids in the mixed sludge were added to the anaerobic reactor at a mass ratio of 0.000124:1:1. After the anaerobic reactor was aerated with nitrogen for 6 min, it was sealed and placed in a water bath constant temperature oscillator with a shaking speed of 125 rpm and a temperature of 35 ℃ for methane production until no more methane was produced in the anaerobic reactor. The cumulative methane production was 153.8 mL / gVSS, and the maximum daily methane production was 25.1 mL.

[0037] Example 3 The rice straw was pyrolyzed at 400 °C for 4 h in the absence of oxygen to obtain biochar material. The biochar was repeatedly washed with deionized water until the soluble ions on its surface were removed. The washed biochar material was dried at 80 °C for 24 h. After drying, the biochar particles with a particle size of 0.1 mm were obtained by sieving. The residual sludge was naturally settled for 24 h, and the settled residual sludge was sieved with a 0.45 mm sieve to remove gravel and large particles of impurities; the sieved residual sludge was heat pretreated at 80 °C for 30 min to obtain pretreated sludge; the inoculated sludge and the pretreated sludge were mixed in a volume ratio of 1:4 to obtain mixed sludge; The signal molecule C8-HSL, biochar particles and volatile suspended solids in the mixed sludge were added to the anaerobic reactor at a mass ratio of 0.000124:1:1. After the anaerobic reactor was aerated with nitrogen for 5 min, the anaerobic reactor was sealed and placed in a water bath constant temperature oscillator with a shaking speed of 120 rpm and a temperature of 34 ℃ for methane production until no more methane was produced in the anaerobic reactor. The cumulative methane production was 156.2 mL / gVSS, and the maximum daily methane production was 24.7 mL.

[0038] Example 4 The straw was pyrolyzed at 500 °C for 2 h in the absence of oxygen to obtain biochar material. The biochar material was repeatedly washed with deionized water until the soluble ions on its surface were removed. The washed biochar material was dried at 65 °C for 28 h. After drying, the biochar particles with a particle size of 0.2 mm were obtained by sieving. The residual sludge was naturally settled for 26 h, and the settled residual sludge was sieved with a 0.45 mm sieve to remove gravel and large particles of impurities; the sieved residual sludge was heat pretreated at 80 °C for 45 min to obtain pretreated sludge; the inoculated sludge and the pretreated sludge were mixed in a volume ratio of 1:4 to obtain mixed sludge; The signal molecule C 10 -HSL, biochar particles and volatile suspended solids in mixed sludge were added to the anaerobic reactor at a mass ratio of 0.000124:1:1. After the anaerobic reactor was aerated with nitrogen for 7 min, it was sealed and placed in a water bath constant temperature oscillator with a shaking speed of 125 rpm and a temperature of 35 °C for methane production until no more methane was produced in the anaerobic reactor. The cumulative methane production was 151.9 mL / gVSS, and the maximum daily methane production was 26.4 mL.

[0039] Example 5 The fruit wood was pyrolyzed at 500 °C for 4 h in the absence of oxygen to obtain biochar material. The biochar material was repeatedly washed with deionized water until the soluble ions on its surface were removed. The washed biochar material was dried at 60 °C for 30 h. After drying, the biochar particles with a particle size of 0.2 mm were obtained by sieving. The residual sludge was naturally settled for 26 h, and the settled residual sludge was sieved with a 0.45 mm sieve to remove gravel and large particles of impurities; the sieved residual sludge was heat pretreated at 80 °C for 50 min to obtain pretreated sludge; the inoculated sludge and the pretreated sludge were mixed in a volume ratio of 1:4 to obtain mixed sludge; The signal molecule C 10 -HSL, biochar particles and volatile suspended solids in mixed sludge were added to the anaerobic reactor at a mass ratio of 0.000124:1:1. After the anaerobic reactor was aerated with nitrogen for 7 min, it was sealed and placed in a water bath constant temperature oscillator with a shaking speed of 130 rpm and a temperature of 36 °C for methane production until no more methane was produced in the anaerobic reactor. The cumulative methane production was 158.1 mL / gVSS, and the maximum daily methane production was 26.9 mL.

[0040] Comparative Example 1 The residual sludge was allowed to settle naturally for 26 h, and the settled residual sludge was sieved with a 0.45 mm sieve to remove gravel and large particles of impurities; the sieved residual sludge was heat pretreated at 80 °C for 40 min to obtain pretreated sludge; the inoculated sludge and pretreated sludge were mixed in a volume ratio of 1:4 to obtain mixed sludge; the mixed sludge was added to the anaerobic reactor, and after the anaerobic reactor was aerated with nitrogen for 7 min, the anaerobic reactor was sealed and placed in a water bath constant temperature oscillator with a shaking speed of 130 rpm and a temperature of 35 °C to produce methane until no methane was produced in the anaerobic reactor.

[0041] Comparative Example 2 The residual sludge was naturally settled for 26 h, and the settled residual sludge was sieved with a 0.45 mm sieve to remove gravel and large particles of impurities; the sieved residual sludge was heat pretreated at 80 °C for 40 min to obtain pretreated sludge; the inoculated sludge and the pretreated sludge were mixed in a volume ratio of 1:4 to obtain mixed sludge; The signal molecule C6-HSL and the volatile suspended solids in the mixed sludge were added to the anaerobic reactor at a mass ratio of 0.000124:1. After the anaerobic reactor was aerated with nitrogen for 7 minutes, the anaerobic reactor was sealed and placed in a water bath constant temperature oscillator with a shaking speed of 130 rpm and a temperature of 35 °C to produce methane until no more methane was produced in the anaerobic reactor.

[0042] Comparative Example 3 The fruit wood was pyrolyzed at 500 °C for 2 h in the absence of oxygen to obtain biochar material. The biochar material was repeatedly washed with deionized water until the soluble ions on its surface were removed. The washed biochar material was dried at 70 °C for 264 h. After drying, the biochar particles with a particle size of 0.2 mm were obtained by sieving. The residual sludge was naturally settled for 26 h, and the settled residual sludge was sieved with a 0.45 mm sieve to remove gravel and large particles of impurities; the sieved residual sludge was heat pretreated at 80 °C for 40 min to obtain pretreated sludge; the inoculated sludge and the pretreated sludge were mixed in a volume ratio of 1:4 to obtain mixed sludge; The biochar particles and the volatile suspended solids in the mixed sludge were added to the anaerobic reactor in a mass ratio of 1:1. After the anaerobic reactor was aerated with nitrogen for 7 min, the anaerobic reactor was sealed and placed in a water bath constant temperature oscillator with a shaking speed of 130 rpm and a temperature of 35 °C to produce methane until no more methane was produced in the anaerobic reactor.

[0043] Comparative Example 4 The fruit wood was pyrolyzed at 500 °C for 2 h in the absence of oxygen to obtain biochar material; the biochar material was repeatedly washed with deionized water until the soluble ions on its surface were removed; the washed biochar material was dried at 70 °C for 26 h; after drying, the biochar particles with a particle size of 0.2 mm were obtained by sieving; The residual sludge was naturally settled for 26 h, and the settled residual sludge was sieved with a 0.45 mm sieve to remove gravel and large particles of impurities; the sieved residual sludge was heat pretreated at 80 °C for 40 min to obtain pretreated sludge; the inoculated sludge and the pretreated sludge were mixed in a volume ratio of 1:4 to obtain mixed sludge; The signal molecule C6-HSL was loaded on the surface of biochar particles to obtain biochar particles loaded with the signal molecule C6-HSL. The biochar particles loaded with the signal molecule C6-HSL were added into an anaerobic reactor. After the anaerobic reactor was aerated with nitrogen for 7 min, the anaerobic reactor was sealed and placed in a water bath constant temperature oscillator with a shaking speed of 130 rpm and a temperature of 35 ℃ to produce methane until no more methane was produced in the anaerobic reactor. The mass ratio of the signal molecule C6-HSL, biochar particles and volatile suspended solids in the mixed sludge was 0.000124:1:1.

[0044] Figure 1 The cumulative methane amount of each group in Example 1 of the present invention and the comparative example is shown in the following figure: Figure 1 As shown, compared with the cumulative methane production of 101.8 mL / gVSS in Comparative Example 1, the cumulative methane production of Example 1 was the highest, reaching 154.7 mL / gVSS, with an increase of 51.9%. The cumulative methane production of Comparative Examples 2 and 3 increased by 28.8% and 9.0%, respectively, indicating that the signal molecule C6-HSL and biochar particles both have a promoting effect on the cumulative methane production, but both the signal molecule C6-HSL and the biochar particles have certain deficiencies in the directional enrichment of functional microorganisms. The signal molecule C6-HSL directional regulation of the population structure and activity of functional microorganisms in the biofilm on the surface of biochar can avoid the non-selectivity in the process of biochar enrichment of microorganisms. At the same time, biochar also provides conditions for the attachment and growth of functional microorganisms regulated by the signal molecule C6-HSL. When the signal molecule C6-HSL is loaded on the surface of biochar particles, that is, the cumulative methane production of Example 4 is only increased by 3.2%, reflecting that the signal molecule C6-HSL is not adsorbed by the biochar particles and has a positive effect on the anaerobic methanogenesis process. It also further illustrates that the signal molecule C6-HSL can promote the anaerobic methanogenesis process by regulating the structure and function of biofilm microorganisms on the biochar surface and the structure and function of suspended microorganisms.

[0045] Figure 2 The figure is a line graph of the methane production rate of each group in Example 1 of the present invention and the comparative example. The results of daily methane production also support this view. Similar to the cumulative methane production performance, the signal molecule AHLs can further increase the maximum daily methane production of the biochar-mediated anaerobic methane production system. Figure 2 As shown, the daily methane production of Example 1 is the highest, which is 25.3 mL, while the daily methane production of Comparative Examples 3, 2 and 4 are 10.1 mL, 9.9 mL and 10.4 mL, respectively. Therefore, the present invention can greatly improve the gas production efficiency of anaerobic digestion of excess sludge in industrial applications, and further exert the production and utilization potential of excess sludge resource utilization.

[0046] In summary, combined with the data results of Examples 2 to 5, it can be shown that the addition of signal molecules AHLs in the present invention significantly improves the efficiency and rate of converting sludge organic matter into methane.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for promoting anaerobic methanogenesis in sludge by strengthening biochar with signal molecules, characterized in that: include: The biochar material is cleaned, dried, ground and sieved to obtain biochar particles; The residual sludge is subjected to sedimentation, screening and thermal pretreatment to obtain pretreated sludge; The pretreated sludge and the inoculated sludge are mixed to obtain mixed sludge; The biochar particles, signal molecules and mixed sludge are added to the anaerobic reactor, and the anaerobic reactor is sealed and placed in a water bath constant temperature oscillator after nitrogen aeration to produce methane until no more methane is produced in the anaerobic reactor; Wherein, the signal molecule is AHLs.

2. The method for promoting anaerobic methanogenesis in sludge by enhancing biochar with signal molecules according to claim 1, characterized in that: The mass ratio of the signal molecule, the biochar particles and the volatile suspended solids in the mixed sludge is 0.000124:1:

1.

3. The method for promoting anaerobic methanogenesis in sludge by enhancing biochar with signal molecules according to claim 1, characterized in that: The preparation method of the biochar material is as follows: pyrolyzing the biomass material under anaerobic conditions at 400-600°C for 2-4 h to obtain the biochar material.

4. The method for promoting anaerobic methanogenesis in sludge by enhancing biochar with signal molecules according to claim 1, characterized in that: The drying conditions of the biochar material are: drying at a temperature not higher than 80°C for not less than 24 hours.

5. The method for promoting anaerobic methanogenesis in sludge by enhancing biochar with signal molecules according to claim 1, characterized in that: The particle size of the biochar particles is 0.1-0.2 mm.

6. The method for promoting anaerobic methanogenesis in sludge by enhancing biochar with signal molecules according to claim 1, characterized in that: The residual sludge settling time is not less than 24 hours.

7. The method for promoting anaerobic methanogenesis in sludge by enhancing biochar with signal molecules according to claim 1, characterized in that: The excess sludge was sieved using a 0.45 mm sieve.

8. The method for promoting anaerobic methanogenesis in sludge by enhancing biochar with signal molecules according to claim 1, characterized in that: The volume ratio of the inoculated sludge to the pretreated sludge is 1:

4.

9. The method for promoting anaerobic methanogenesis in sludge by enhancing biochar with signal molecules according to claim 1, characterized in that: The heat pretreatment condition is: heat pretreatment at 80°C for no less than 30 min.

10. The method for promoting anaerobic methanogenesis in sludge by enhancing biochar with signal molecules according to claim 1, characterized in that: The shaking speed of the water bath constant temperature oscillator is 120~130 rpm and the temperature is 35±1℃.

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