Method for preparing hydrothermal carbon by coupling anaerobic fermentation with microwave hydrothermal carbonization of antibiotic mushroom dregs

Abstract

The invention discloses a method for preparing hydrothermal carbon by coupling anaerobic fermentation with microwave hydrothermal carbonization of antibiotic mushroom dregs, and belongs to the technical field of solid waste resource utilization. The method comprises the following steps: carrying out anaerobic fermentation by taking antibiotic mushroom dregs as a substrate and cow dung as an inoculum for 18-20 days, and carrying out daily gas collection and discharged material collection according to the set anaerobic fermentation time to obtain biogas residues and biogas slurry; and carrying out microwave hydrothermal carbonization on the obtained biogas residue and biogas slurry to obtain the hydrothermal carbon. According to the method, the antibiotic mushroom dregs are used as raw materials, and efficient conversion from the antibiotic mushroom dregs to the hydrothermal carbon is realized by virtue of a method of coupling anaerobic fermentation with microwave hydrothermal carbonization; the method solves the problem that residues are difficult to treat when antibiotic mushroom dregs are treated through anaerobic fermentation and the problem that the product yield is low when the antibiotic mushroom dregs are directly subjected to hydrothermal carbonization to prepare the hydrothermal carbon.

Description

Technical Field

[0001] The invention belongs to the technical field of solid waste resource utilization, and more specifically relates to a method for preparing hydrothermal carbon by utilizing anaerobic fermentation of antibiotic bacterial residue coupled with microwave hydrothermal carbonization. Background Art

[0002] Antibiotic residue is a solid waste produced by microbial fermentation during the production of antibiotic drugs. Antibiotic residue is a hazardous waste with a large output, high water content, high nitrogen and sulfur content, and residual antibiotics. It should be treated in accordance with the requirements for hazardous waste. Therefore, antibiotic residue poses a huge threat to the environment, and its scientific, harmless and resource-based treatment is an important difficulty in the treatment of solid waste in the medical and pharmaceutical industries. The safe treatment and resource utilization of antibiotic residue is not only a necessary measure to protect the environment and human health, but also an urgent need to comply with regulatory requirements, respond to pollution status and technological development trends.

[0003] At present, there are two main channels for the treatment of antibiotic residues: one is to directly carry out hydrothermal carbonization to prepare hydrothermal charcoal. Although this treatment method can achieve pollution-free treatment of antibiotic residues, it has the problem of low hydrothermal charcoal yield and inability to achieve efficient recycling of antibiotic residues. The other is to anaerobic fermentation of antibiotic residues to produce biogas mainly composed of CH4 and CO2, but its by-products (biogas residues and biogas liquid) are difficult to digest, there is still environmental pollution, and it is impossible to achieve efficient recycling of antibiotic residues.

[0004] In view of this, it is of great significance to develop a green and environmentally friendly method for preparing hydrothermal carbon using antibiotic bacterial residue, which can achieve efficient conversion of antibiotic bacterial residue and increase the yield of hydrothermal carbon. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing hydrothermal charcoal by coupling anaerobic fermentation of antibiotic bacterial residue with microwave hydrothermal carbonization, so as to solve the problem of disposing of by-products of anaerobic fermentation of antibiotic bacterial residue, especially harmful biogas residue and liquid, and at the same time significantly improve the yield of hydrothermal charcoal with broad application prospects, so as to realize the full utilization of antibiotic bacterial residue.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] One of the technical solutions of the present invention is to provide a method for preparing hydrothermal carbon by anaerobic fermentation of antibiotic bacterial residue coupled with microwave hydrothermal carbonization, comprising the following steps:

[0008] Anaerobic fermentation is carried out with antibiotic bacterial residue as substrate and cow dung as inoculum. The cycle of anaerobic fermentation is 18 to 20 days. Feeding, gas collection and discharge are carried out daily according to the set anaerobic fermentation time to obtain biogas residue and biogas liquid. The obtained biogas residue and biogas liquid are subjected to microwave hydrothermal carbonization to obtain the hydrothermal charcoal.

[0009] The present invention uses antibiotic bacterial residue as raw material, and realizes efficient conversion of antibiotic bacterial residue to hydrothermal carbon by means of anaerobic fermentation coupled with microwave hydrothermal carbonization, thereby solving the problem of difficulty in treating the residue in anaerobic fermentation treatment of antibiotic bacterial residue and the problem of low product yield in the preparation of hydrothermal carbon by direct hydrothermal carbonization of antibiotic bacterial residue. Among them, anaerobic fermentation is carried out with antibiotic bacterial residue as substrate and cow dung as inoculum. Cow dung contains a large amount of organic matter and nutrients, especially trace elements such as nitrogen, phosphorus, and potassium. These components can provide necessary nutrients in the anaerobic fermentation process and promote the growth and reproduction of microorganisms. By adding cow dung as inoculum, the fermentation effect can be improved, and the quality and yield of the fermentation product can be increased; the synergistic effect of anaerobic fermentation and microwave hydrothermal carbonization can ensure that the biogas slurry and biogas residue obtained by anaerobic fermentation are fully utilized, and the humification degree of the raw materials is improved through anaerobic fermentation. The obtained biogas residue and biogas slurry are used for microwave hydrothermal carbonization, and a high-yield hydrothermal carbon is obtained through a series of reactions such as hydrolysis, dehydration, decarboxylation, polymerization and aromatization.

[0010] The raw materials used in the present invention are waste materials, and no other chemical reagents are introduced in the entire process. In addition, usable biogas and hydrothermal charcoal are finally prepared, which is environmentally friendly and realizes the efficient recovery and reuse of antibiotic bacterial residues.

[0011] Preferably, the antibiotic residue includes one or more of gentamicin residue, oxytetracycline residue and avermectin residue; the particle size of the antibiotic residue is 20 to 60 meshes; and the residual amount of antibiotic in the antibiotic residue is less than 3 mg / kg.

[0012] More preferably, the antibiotic bacterial residue is crushed and sieved to a specific particle size and then placed in a cool and dry place for later use.

[0013] Preferably, the cow dung is placed in 36-38° C. water for fermentation before anaerobic fermentation to ensure the activity of microorganisms therein, and after the fermentation is completed, the effluent is collected for anaerobic fermentation.

[0014] Preferably, during the anaerobic fermentation process, the TS of the initial anaerobic fermentation system is 2-6%, and the TS of the feed is 2-6%.

[0015] Preferably, the temperature of the anaerobic fermentation is 36-38°C.

[0016] Preferably, the hydraulic retention time of the anaerobic fermentation is 18 to 20 days; the system organic load rate of the anaerobic fermentation is 2 to 4 gTS / (L·d).

[0017] Preferably, during the anaerobic fermentation process, feeding and discharging are performed daily according to a calculation result of an organic loading rate of 2 to 4 gVS / (L·d).

[0018] More preferably, during the anaerobic fermentation, the anaerobic fermentation system is shaken 10 to 15 times per day; each shaking lasts for 10 to 20 minutes; the purpose of the shaking is to prevent slagging on the surface of the anaerobic fermentation system.

[0019] More preferably, the reactor used for the anaerobic fermentation is connected to a water bath to circulate hot water for heat preservation.

[0020] More preferably, the step of processing the collected output after the anaerobic fermentation is completed comprises: obtaining biogas residue and biogas liquid by filtering, drying, grinding and sieving the biogas residue in sequence, and taking the sieved material and the biogas liquid as raw materials for microwave hydrothermal carbonization;

[0021] The drying temperature is 104-106°C; the mesh size of the sieve used for sieving is 30-60 meshes.

[0022] More preferably, the gas collected during the anaerobic fermentation comprises biogas, which comprises hydrogen, nitrogen, methane and carbon dioxide.

[0023] Preferably, the solid-liquid ratio during the microwave hydrothermal carbonization is 1 g:29 mL.

[0024] Preferably, the temperature of the microwave hydrothermal carbonization is 160-200° C., the power of the microwave hydrothermal carbonization is 800 W, and the time of the microwave hydrothermal carbonization is 30-120 min.

[0025] The present invention discloses the following technical effects:

[0026] 1. The present invention adopts anaerobic fermentation coupled with hydrothermal carbonization to treat antibiotic bacterial residue, which significantly improves the utilization rate of antibiotic bacterial residue. The yield of the obtained hydrothermal charcoal is greatly improved compared with the traditional hydrothermal carbonization treatment of antibiotic bacterial residue alone.

[0027] 2. The present invention uses antibiotic bacterial residues which have large and concentrated production and may cause environmental pollution if not properly handled as raw materials, thus realizing resource utilization of waste and reducing the risk of environmental pollution.

[0028] 3. The entire process of the present invention does not introduce other chemical reagents and is environmentally friendly. DETAILED DESCRIPTION

[0029] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0030] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0031] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0032] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0033] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0034] The present invention first describes the raw materials and parameters involved in the following examples and comparative examples:

[0035] The cow dung used was obtained from a breeding farm in Tianjin, and the TS of cow dung was 30.66±0.03%;

[0036] The cow dung used was activated in a jar in a 37°C water bath before anaerobic fermentation.

[0037] The gentamicin residue used was obtained from a pharmaceutical company in Tianjin; other raw materials were all commercially available products unless otherwise specified.

[0038] The used gentamicin residue was processed as follows for later use: the gentamicin residue was mechanically crushed, and sieved using a screening device to obtain 35-mesh gentamicin residue, which was placed in a cool and dry place for later use.

[0039] The TS (Total Solid) involved refers to the total solid concentration, that is, the solid content in the fermentation raw materials after removing water; the VS involved refers to the material remaining after removing the ash from the total solids of the raw materials.

[0040] The calculation formula of the hydrothermal charcoal yield is:

[0041] Among them, Y C is the hydrothermal charcoal yield, %; M C is the mass of hydrothermal charcoal obtained by the reaction, g; M D is the mass of raw material (biogas residue) in microwave hydrothermal carbonization reaction, g.

[0042] Example 1

[0043] This embodiment provides a method for synthesizing hydrothermal carbon by anaerobic fermentation of antibiotic bacterial residue coupled with microwave hydrothermal carbonization, the steps are as follows:

[0044] Anaerobic fermentation was carried out with gentamicin residue as substrate and cow dung as inoculum. The TS of the initial operating system was set to 5%. Then, anaerobic fermentation was carried out in a 5L CSTR reactor, with a hydraulic retention time of 20d, an organic load rate of 2gTS / (L·d), and a feed TS of 4%. During the anaerobic fermentation process, feeding and discharging were carried out daily according to the calculation result of the organic load rate of 2gVS / (L·d). The anaerobic fermentation temperature was set to 37℃, and the anaerobic fermentation cycle was set to 20d. The reaction system maintained the anaerobic fermentation temperature at 37℃ through a circulating water bath. It was shaken 10 times a day, and each shaking time was 10min to avoid surface hardening and slagging. The material was fed and discharged at regular intervals every day, and the air bag was replaced. The daily gas production and gas components were measured. The experiment was stopped when the daily gas production fluctuated less than 10% compared with the average daily gas production, and the daily discharge was separated into solid and liquid using a 200-mesh nylon filter. The filtered solid was placed in an oven at 105°C and dried completely, then crushed through a 35-mesh sieve, the sieve residue (biogas residue) was placed in a ziplock bag for sealing, and the filtered liquid (biogas liquid) was stored in a refrigerator. 10g of biogas residue and 290mL of biogas liquid were added to the microwave hydrothermal reactor for microwave hydrothermal carbonization reaction. The reaction temperature was adjusted to 160°C, the power was 800W, and the time was 30min. After the reaction was completed, the equipment was cooled to room temperature, and the solid-liquid separation was performed by suction filtration. The obtained solid was dried to obtain hydrothermal charcoal, weighed and recorded, and stored in a sealed bag.

[0045] The hydrothermal charcoal yield was found to be 85.81%.

[0046] Example 2

[0047] The difference from Example 1 is that the microwave hydrothermal carbonization reaction temperature is adjusted to 180° C., and the rest is the same as Example 1.

[0048] The hydrothermal charcoal yield was found to be 80.97%.

[0049] Example 3

[0050] The difference from Example 1 is that the microwave hydrothermal carbonization reaction temperature is adjusted to 200° C., and the rest is the same as Example 1.

[0051] The hydrothermal charcoal yield was found to be 70.86%.

[0052] Example 4

[0053] The difference from Example 1 is that the microwave hydrothermal carbonization reaction time is adjusted to 60 min, and the rest is the same as Example 1.

[0054] The hydrothermal charcoal yield was found to be 85.17%.

[0055] Example 5

[0056] The difference from Example 1 is that the microwave hydrothermal carbonization reaction time is adjusted to 90 min, and the rest is the same as Example 1.

[0057] The hydrothermal charcoal yield was found to be 81.26%.

[0058] Example 6

[0059] The difference from Example 1 is that the microwave hydrothermal carbonization reaction time is adjusted to 120 min, and the rest is the same as Example 1.

[0060] The hydrothermal charcoal yield was found to be 83.87%.

[0061] Comparative Example 1

[0062] Add 10g of gentamicin residue and 290mL of deionized water to the microwave hydrothermal reactor for microwave hydrothermal carbonization reaction. The reaction temperature was regulated to 160°C, the power was 800W, and the time was 30min. After the reaction, the equipment was cooled to room temperature, and the solid-liquid separation was performed by suction filtration. The obtained solid was dried to obtain hydrothermal carbon, weighed and recorded, and stored in a sealed bag.

[0063] The hydrothermal charcoal yield was found to be 79.63%.

[0064] Comparative Example 2

[0065] The difference from Comparative Example 1 is that the microwave hydrothermal carbonization reaction temperature is adjusted to 180° C., and the rest is the same as Comparative Example 1.

[0066] The hydrothermal charcoal yield was found to be 77.80%.

[0067] Comparative Example 3

[0068] The difference from Comparative Example 1 is that the microwave hydrothermal carbonization reaction temperature is adjusted to 200° C., and the rest is the same as Comparative Example 1.

[0069] The hydrothermal charcoal yield was found to be 63.50%.

[0070] Comparative Example 4

[0071] The difference from Comparative Example 1 is that the microwave hydrothermal carbonization reaction time is adjusted to 60 min, and the rest is the same as Comparative Example 1.

[0072] The hydrothermal charcoal yield was found to be 80.24%.

[0073] Comparative Example 5

[0074] The difference from Comparative Example 1 is that the microwave hydrothermal carbonization reaction time is adjusted to 90 min, and the rest is the same as Comparative Example 1.

[0075] After testing, the hydrothermal charcoal yield was 81.53%.

[0076] Comparative Example 6

[0077] The difference from Comparative Example 1 is that the microwave hydrothermal carbonization reaction time is adjusted to 120 min, and the rest is the same as Comparative Example 1.

[0078] The hydrothermal charcoal yield was found to be 76.93%.

[0079] By comparing Examples 1 to 6 with Comparative Examples 1 to 6, it can be seen that the yield of hydrothermal charcoal by the method described in the embodiments can reach up to 85.81%, compared with the maximum of 81.53% in the comparative example. The method described in the present invention can achieve a significant increase in the yield of hydrothermal charcoal without affecting the output of biogas.

[0080] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0081] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing hydrothermal carbon by anaerobic fermentation of antibiotic bacterial residue coupled with microwave hydrothermal carbonization, characterized in that: The steps include: Anaerobic fermentation is carried out with antibiotic bacterial residue as substrate and cow dung as inoculum. The cycle of anaerobic fermentation is 18 to 20 days. Feeding, gas collection and discharge are carried out daily according to the set anaerobic fermentation time to obtain biogas residue and biogas liquid. The obtained biogas residue and biogas liquid are subjected to microwave hydrothermal carbonization to obtain the hydrothermal charcoal.

2. The method for preparing hydrothermal carbon by anaerobic fermentation of antibiotic bacterial residue coupled with microwave hydrothermal carbonization according to claim 1, characterized in that: The antibiotic residue comprises one or more of gentamicin residue, oxytetracycline residue and avermectin residue; the particle size of the antibiotic residue is 20-60 meshes; and the residual amount of antibiotic in the antibiotic residue is less than 3 mg / kg.

3. The method for preparing hydrothermal carbon by anaerobic fermentation of antibiotic bacterial residue coupled with microwave hydrothermal carbonization according to claim 1, characterized in that: The cow dung is placed in water at 36-38° C. for fermentation before anaerobic fermentation.

4. The method for preparing hydrothermal carbon by anaerobic fermentation of antibiotic bacterial residue coupled with microwave hydrothermal carbonization according to claim 1, characterized in that: During the anaerobic fermentation process, the TS of the initial anaerobic fermentation system is 2-6%, and the TS of the feed is 2-6%.

5. The method for preparing hydrothermal carbon by anaerobic fermentation of antibiotic bacterial residue coupled with microwave hydrothermal carbonization according to claim 1, characterized in that: The temperature of the anaerobic fermentation is 36-38°C.

6. The method for preparing hydrothermal carbon by anaerobic fermentation of antibiotic bacterial residue coupled with microwave hydrothermal carbonization according to claim 1, characterized in that: The hydraulic retention time of the anaerobic fermentation is 18 to 20 days; the organic load rate of the anaerobic fermentation system is 2 to 4 gTS / (L·d).

7. The method for preparing hydrothermal carbon by anaerobic fermentation of antibiotic bacterial residue coupled with microwave hydrothermal carbonization according to claim 1, characterized in that: During the anaerobic fermentation process, feeding and discharging are performed daily according to the calculation result of an organic loading rate of 2 to 4 gVS / (L·d).

8. The method for preparing hydrothermal carbon by anaerobic fermentation of antibiotic bacterial residue coupled with microwave hydrothermal carbonization according to claim 1, characterized in that: The solid-liquid ratio during the microwave hydrothermal carbonization is 1 g:29 mL.

9. The method for preparing hydrothermal carbon by anaerobic fermentation of antibiotic bacterial residue coupled with microwave hydrothermal carbonization according to claim 1, characterized in that: The temperature of the microwave hydrothermal carbonization is 160-200° C., the power of the microwave hydrothermal carbonization is 800 W, and the time of the microwave hydrothermal carbonization is 30-120 min.