CN114438135A - A kind of quick start method of high temperature dry anaerobic fermentation of kitchen waste - Google Patents

Abstract

The present invention provides a quick start method for high-temperature dry anaerobic fermentation of kitchen waste, comprising: S1, adding 50% of the effective volume of water to the system; S2, raising the temperature of the system to 55°C and maintaining it; S3, adding the effective volume to the system 40% volume of multi-microorganisms start the inoculum; S4, add a fast-absorbing nutrient source of 10% of the effective volume to the system; S5, mechanically stir the system, and pump an amount of 12-15% of the effective volume every 24 hours; S6 . Quantitatively monitor various indexes of the system; S7, the index fluctuation is less than or equal to 30% and maintained for 7 days, the fermentation system is successfully started. The invention uses water as the system medium to rapidly raise the temperature to 55°C, the heating time is short, the start-up time is reduced, the multiple microorganisms, the problem of unbalanced microorganism species and quantity is solved, the anaerobic environment can be quickly formed, and the mechanical stirring and pumping cycle can form a complete mixing The system can speed up mass transfer and microbial metabolic reproduction, which is conducive to the interactive flow of different parts of the system, and quickly forms a stable high-temperature dry anaerobic fermentation system.

Description

A kind of quick start method of high temperature dry anaerobic fermentation of kitchen waste

technical field

The invention relates to the field of kitchen waste treatment, in particular to a quick start method for high-temperature dry anaerobic fermentation of kitchen waste.

Background technique

Kitchen waste refers to organic waste that is generally generated by household waste classification and produced during food processing and eating, mainly including fruit and vegetable residues, leftovers, fruit shells and eggshells, spoiled food, etc. Kitchen waste often contains solid debris such as plastic bags (sheets), glass, gravel, metal, etc. Generally, before dry anaerobic kitchen waste, it needs to be sorted and pretreated to remove the above solid debris, and the organic part is subjected to dry anaerobic treatment. Digestion and treatment are converted into biogas, etc., so as to realize the resource treatment of organic waste.

Due to the high carbon content of kitchen waste, the high-temperature dry anaerobic fermentation of large-scale kitchen waste increases the adaptability of microorganisms due to the unbalanced types and numbers of fermentation acid-producing bacteria and methanogens during the start-up period, which may easily lead to system rancidity during the start-up period. In addition, kitchen waste forms a dry anaerobic fermentation system with multiphase flow and high solid content as the fermentation substrate. The diffusion of substance molecules and eddy currents are poor, and it is difficult for different sections of the system to flow alternately to form a stable high-temperature dry anaerobic fermentation system. . Moreover, in the currently used high-temperature dry anaerobic fermentation, the temperature has a great influence on the microorganisms, so the temperature is gradually increased, resulting in a long start-up time and low efficiency.

Therefore, it is necessary to propose a rapid start-up method for high-temperature dry anaerobic fermentation of kitchen waste to solve the above problems.

SUMMARY OF THE INVENTION

A series of concepts in simplified form have been introduced in the Summary section, which are described in further detail in the Detailed Description section. The Summary of the Invention section of the present invention is not intended to attempt to limit the key features and essential technical features of the claimed technical solution, nor is it intended to attempt to determine the protection scope of the claimed technical solution.

Aiming at the deficiencies of the prior art, the present invention proposes a quick start method for high-temperature dry anaerobic fermentation of kitchen waste, including: S1, adding 50% of the effective volume of water to the system; S2, raising the temperature of the system to 55°C and maintaining ; S3, the system is added with 40% of the effective volume of the multi-microorganism to start the inoculum; S4, the system is added with 10% of the effective volume of the fast-absorbing nutrient source; S5, the system is mechanically stirred, and the effective volume is pumped every 24 hours. The amount of 12-15%; S6, quantitatively monitor various indicators of the system; S7, the index fluctuation is less than or equal to 30% and maintained for 7 days, the fermentation system is successfully started.

Optionally, the multi-microorganism start-up inoculum in S3 includes the addition of cow dung, activated sludge, and aerobic fermentation stock that are added sequentially at a time interval of 24 hours.

Optionally, the addition ratio of the cow dung, activated sludge, and aerobic fermentation stock is 3:1:1.

Optionally, the nutrient source includes various sources of kitchen waste with a crushed particle size of ≤20 mm.

Optionally, the nutrient source further includes iron additives.

Optionally, the addition ratio of the iron additive is 1/500-1/300 of the starting inoculation species.

Optionally, after adding the nutrient source in S4, mix well, and place at a moderate temperature of 30-35° C. for 15-20 hours.

Optionally, the speed of the mechanical stirring is 2-4r/min.

Optionally, between S5 and S6 also includes supplementing the nutrient source according to the material metabolism balance.

Optionally, the indicators include biogas production, biogas composition, system pH, and total organic acid content in the system.

The invention provides a quick-start method for high-temperature dry anaerobic fermentation of kitchen waste, which adopts water as a system medium to rapidly increase the temperature to 55°C, has a short heating time, reduces the start-up time, and has multiple microorganisms to solve the problem of unbalanced types and quantities of microorganisms. , can quickly form an anaerobic environment, mechanical stirring and pumping circulation to form a fully mixed system can speed up mass transfer and microbial metabolism and reproduction, which is conducive to the interactive flow of different parts of the system, and quickly form a stable high-temperature dry anaerobic fermentation system. From the current 30-40 days to 7 days.

Description of drawings

The following drawings of the present invention are incorporated herein as a part of the present invention for understanding of the present invention. The accompanying drawings illustrate embodiments of the present invention and their description, which serve to explain the apparatus and principles of the present invention. In the attached drawings,

Fig. 1 is the flow chart of the quick start method of high temperature dry anaerobic fermentation of kitchen waste in one embodiment of the present invention;

Fig. 2 is a flow chart of a quick start method for high-temperature dry anaerobic fermentation of kitchen waste according to another embodiment of the present invention.

Detailed ways

In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without one or more of these details. In other instances, some technical features known in the art have not been described in order to avoid obscuring the present invention.

For a thorough understanding of the present invention, detailed steps will be presented in the following description in order to explain the method proposed by the present invention. Obviously, the practice of the present invention is not limited to the specific details familiar to those skilled in the art. Preferred embodiments of the present invention are described in detail below, however, the present invention may have other embodiments in addition to these detailed descriptions.

It should be understood that when the terms "comprising" and/or "comprising" are used in this specification, they indicate the presence of said features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or Various other features, integers, steps, operations, elements, components and/or combinations thereof.

Anaerobic fermentation, also known as biogas fermentation, refers to the catabolism of organic matter (urban organic solid waste, agricultural organic waste, etc.) under certain moisture, temperature and anaerobic conditions, through the catabolism of various microorganisms, and finally forms combustibles such as methane and carbon dioxide. Sexual mixed gas process.

High temperature dry anaerobic fermentation is a form of anaerobic fermentation, the fermentation temperature is 50-55°C, and the solid content of organic matter in the fermentation system is greater than 18%.

Anaerobic fermentation can be divided into wet anaerobic and dry anaerobic according to the difference of solid content. Among them, dry anaerobic has the characteristics of high volume load, high gas production rate, and easy processing of fermentation products. The anaerobic type has the advantages of high fermentation efficiency, high processing load, killing pathogenic microbes, etc. It can effectively deal with the characteristics of high organic solid content in kitchen waste and easy spoilage to breed pathogenic bacteria. The disadvantage of easy to start instability. Stable and fast high temperature anaerobic start-up requires inoculation of high temperature acclimated anaerobic sludge (a source of microorganisms required for high temperature dry anaerobic fermentation). For large-scale kitchen waste dry anaerobic projects, a large amount of high-temperature anaerobic sludge is required, and the start-up time is short. In addition, the kitchen waste dry anaerobic project is still in the initial development stage of the industry, and there are few operating projects. Considering the project's anaerobic start-up requirements, Transportation radius, etc., the cost of obtaining anaerobic sludge is high, and sufficient anaerobic sludge cannot be obtained for startup.

High-efficiency and rapid start-up of high-temperature dry anaerobic fermentation requires diverse microorganisms and rich nutrient sources. Currently, industrial waste yeast or activated feed yeast are used as nutrient source substrates. 1.5 ratio, in addition, it is necessary to use nitrogen or biogas for purging for 3-30 minutes, and inoculation realizes the start of dry anaerobic fermentation. During the start-up stage, a large amount of nitrogen or biogas is required to purge the reactor, and the inoculum of yeast activation used is large ( It accounts for 1-9% of the material quality), and it is not easy to obtain, and the cost is high. In the actual start-up of large and medium-sized dry anaerobic fermentation projects, it is easy to have insufficient purging conditions and insufficient start-up nutrients, which is difficult to promote in the project. application.

In addition, when starting, inoculate fresh cow dung or cow farm biogas slurry according to the proportion of 15-25% of the material, and use the solid-liquid separation liquid backflow to control the solid content of the material to 10-20%, and supplement the nitrogen source (pig manure) every 10-20 days. , control the parameters such as inoculation and material return in the start-up stage, and realize dry anaerobic start-up. The use of separated liquid reflux controls the solid content of the material, but it is easy to cause the loss of fermentation microorganisms with the separated solids, which is not conducive to the rapid start of dry anaerobicity.

The pretreated fibrous material and livestock and poultry manure are mixed and batched according to the carbon-nitrogen ratio of 20-30:1, and the rumen biological agent is added to start the process of hydrolysis, acidification and methane production, and the pH of the start-up process is adjusted to 6.5-7.5. The addition of anaerobic microbial inoculants in this method can promote the balance of hydrolysis, acidification and methane production. The start of dry anaerobic engineering requires a large amount of anaerobic microbial inoculants, and the domestication requires a large amount of medium, and the domestication time is long, which is not conducive to the rapid start of large and medium-sized dry anaerobic projects.

The anaerobic fermentation process can be divided into the stages of hydrolysis, acidification, acetic acid production, hydrogen production and methane production. The dry anaerobic system has high solid content and uneven mass transfer, and the four stages of anaerobic fermentation cannot be effectively coordinated and balanced. In the prior art, the source of microbial inoculum is single, which is not conducive to the dry anaerobic system covering the high diversity microorganisms required for the four stages of fermentation; in order to improve the adaptability of microorganisms in the prior art, the temperature of the anaerobic system is gradually increased, and it takes a long time to reach the fermentation stage. It is difficult to obtain a large amount of nutrients and inoculum required for starting dry anaerobic fermentation in the prior art, and the acquisition cost is high, which is not conducive to the start-up of large and medium-sized dry anaerobic fermentation projects.

Therefore, the present invention aims at this, and invents a dry anaerobic starting method suitable for large and medium-sized large-scale kitchen waste dry anaerobic fermentation projects, which is easy to obtain, quick to start, low cost and easy to control. Stable operation provides basic conditions.

Aiming at the problems of long start-up time and low efficiency of high-temperature dry anaerobic fermentation, the dry anaerobic high-temperature fermentation system was quickly started by methods such as sudden increase in fermentation temperature, multi-source inoculum, rapid absorption of nutrient sources, and formation of a complete mixed system.

The starting method of the present invention will be further described below with reference to the accompanying drawings.

As shown in FIG. 1 , in at least one embodiment, a method for fast start-up of high-temperature dry anaerobic fermentation of kitchen waste includes: S1, adding 50% of the effective volume of water to the system; S2, raising the temperature of the system to 55°C and maintaining ; S3, the system adds 40% of the effective volume of the multi-microorganism to start the inoculum; S4, the system adds 10% of the effective volume of the fast-absorbing nutrient source; S5, the mechanical stirring system, every 24 hours pumping and circulating the amount of 12-15% of the effective volume ; S6, quantitative monitoring system indicators; S7, indicator fluctuations ≤ 30% and maintained for 7 days, the fermentation system was successfully started.

In at least one embodiment, the multi-microorganism start-up inoculum in S3 includes cow dung, activated sludge, and aerobic fermentation stock that are added sequentially at a time interval of 24 hours.

In at least one embodiment, the addition ratio of cow dung, activated sludge, and aerobic fermentation stock is 3:1:1.

In at least one embodiment, the nutrient source includes various sources of kitchen waste with a crushed particle size ≤ 20 mm.

In at least one embodiment, the nutritional source further includes iron-based additives.

In at least one embodiment, the addition ratio of the iron additive is 1/500-1/300 of the starting inoculation species.

In at least one embodiment, after the nutrient source is added in S4, it is mixed well and placed at a moderate temperature of 30-35° C. for 15-20 hours.

In at least one embodiment, the rate of the mechanical agitation is 2-4 r/min.

In at least one embodiment, between S5 and S6 further includes supplementing a nutrient source according to a material metabolism balance, as shown in FIG. 2 .

In at least one embodiment, the indicators include biogas production, biogas composition, system pH, that is, pH value of the system, total organic acid content of the system, that is, total VFAs of the system, and the like.

In at least one embodiment, a method for rapid start-up of high-temperature dry anaerobic fermentation of kitchen waste includes the following steps:

1. Obtain the starting base temperature of the dry anaerobic fermentation system at 55°C (ie, the stable fermentation temperature): add 50% of the effective volume of the anaerobic system to the system. Natural water, reclaimed water, tap water, etc., through the circulating water heating system of the dry anaerobic system, the water in the system is raised to 55 °C, and the base temperature is maintained at 55 °C. This process can effectively increase molecular diffusion and eddy current diffusion;

2. Multi-source organic corrosive materials are assembled to form multi-microbial starting inoculum: inoculum such as cow dung, aerobic fermentation stack, activated sludge, etc. are obtained nearby. In the dry anaerobic fermentation system maintained at a base temperature of 55 °C, cow dung, activated sludge, and aerobic fermentation stacks were added in sequence, the addition time interval was 24 hours, the addition ratio was 3:1:1, and the addition amount was the anaerobic system. 40% of the effective volume. The characteristics of the added cow dung are TS=18-23%, VS (% wet weight)=15%-20%, C/N=20-24; 60℃) stacking material, the characteristics are TS=30-40%, VS (% wet weight)=20-25%, C/N=10-13; the physical and chemical properties of the added activated sludge are TS=18-22%, VS (wet weight)=30-40%, C/N=5-7. The purpose of adding in sequence at intervals of 24h is to prevent sudden changes in temperature from affecting the adaptability of microorganisms and maintain the diversity of microorganisms in the system.

3. Add a fast-absorbing nutrient source to the system: fully crush the kitchen waste from various sources to a homogeneous phase (no pores, no stratification, no precipitation), and the crushed particle size is less than or equal to 20mm. Add iron additives (iron and iron oxides), the amount of addition is 1/500-1/300 of the starting inoculum, mix well, and place it at medium temperature (30-35°C) for 15-20h to form a dissolved state. And the rapid absorption nutrient source of suspended organic carbon source, organic nitrogen source, organic matter and iron combined complex, the nutrient source is added to 10% of the effective volume of the fermentation system.

4. Use mechanical stirring and pumping circulation to realize material diffusion and microbial activity in the system: the mechanical stirring rate is set to 2-4r/min, and the pumping circulation is the amount of 12-15% of the effective volume per 24 hours.

5. Maintain sufficient nutrient source in the system: Detect the amount of methane and carbon dioxide produced by the metabolism of the system, and supplement the nutrient source (kitchen waste + iron additives) according to the material metabolism balance.

6. Quantitative monitoring of biogas production, biogas composition, pH of the system, total VFAs (total organic acids) and other indicators in the system: if the above indicators fluctuate ≤30% and maintain for 7 days, the fermentation system can be successfully started.

Based on the above description, the startup method proposed by the present invention has at least the following advantages:

1. Using water as the system medium, the temperature is suddenly raised to 55 °C, the heating time is short, and the start-up time is reduced.

2. Multi-source organic corrosive materials added in a certain proportion can effectively increase the diversity of anaerobic microorganisms, solve the problem of unbalanced microbial species and quantity, especially increase the types of high temperature resistant anaerobic microorganisms, which is conducive to the rapid and stable start of the system; In addition, because activated sludge and aerobic fermentation stacks have a large number of aerobic microorganisms, they can quickly form an anaerobic environment. Due to the rich variety, they are basically not affected by the rapid increase in temperature.

3. The broken kitchen waste is mixed with iron additives and placed under medium temperature conditions (30-35°C), and the formed complex of organic matter and iron is conducive to the growth and reproduction of methanogens.

4. Mechanical stirring and pumping circulation to form a fully mixed system can speed up mass transfer and microbial metabolism and reproduction, which is conducive to the interactive flow of different sections of the system, and quickly forms a stable high-temperature dry anaerobic fermentation system.

Unless otherwise defined, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field of this invention. The terminology used herein is for the purpose of describing a particular implementation only and is not intended to limit the present invention. Terms such as "disposed" appearing herein may mean that one element is directly attached to another element or that one element is attached to another element through an intermediary piece. A feature described herein in one embodiment may be used in another embodiment alone or in combination with other features, unless the feature is not applicable in the other embodiment or stated otherwise.

The present invention has been described by the above-mentioned embodiments, but it should be understood that the above-mentioned embodiments are only for the purpose of illustration and description, and are not intended to limit the present invention to the scope of the described embodiments. In addition, those skilled in the art can understand that the present invention is not limited to the above-mentioned embodiments, and more variations and modifications can also be made according to the teachings of the present invention, and these variations and modifications all fall within the protection claimed in the present invention. within the range. The protection scope of the present invention is defined by the appended claims and their equivalents.

Claims (10)

1. a kind of kitchen waste high temperature dry anaerobic fermentation quick start method, is characterized in that, comprises: S1. Add 50% water in effective volume to the system; S2, the temperature of the system is raised to 55°C and maintained; S3, adding the multi-microorganism starting inoculum with an effective volume of 40% to the system; S4, the system is added with a fast-absorbing nutrient source of 10% of the effective volume; S5. Mechanically stir the system, and pump an amount of 12-15% of the effective volume of the circulation every 24 hours; S6. Quantitatively monitor various indicators of the system; S7, the index fluctuation is less than or equal to 30% and maintained for 7 days, the fermentation system is successfully started. 2 . The start-up method according to claim 1 , wherein the multi-microorganism start-up inoculum in S3 comprises cow dung, activated sludge, and aerobic fermentation stock that are added sequentially at a time interval of 24 hours. 3 . 3. The startup method according to claim 2, wherein the addition ratio of the cow dung, activated sludge, and aerobic fermentation stock is 3:1:1. 4 . The startup method according to claim 1 , wherein the nutrient source comprises various sources of kitchen waste with a crushed particle size ≤ 20 mm. 5 . 5 . The starting method according to claim 4 , wherein the nutrient source further comprises iron additives. 6 . 6 . The start-up method according to claim 5 , wherein the addition ratio of the iron-based additive is 1/500-1/300 of the start-up inoculation species. 7 . 7 . The start-up method according to claim 1 , characterized in that after adding the nutrient source in S4 , fully mixing, and placing at a moderate temperature of 30-35° C. for 15-20 hours. 8 . 8. The starting method according to claim 1, wherein the speed of the mechanical stirring is 2-4r/min. 9 . The start-up method according to claim 1 , wherein between S5 and S6 , the method further comprises supplementing a nutrient source according to a material metabolism balance. 10 . 10 . The startup method according to claim 1 , wherein the indicators include biogas production, biogas composition, system pH, and total organic acid content in the system. 11 .

Images