阅读说明：本技术 一种优化物料组分促进易腐有机固废厌氧消化产沼气的方法 (Method for optimizing material components and promoting anaerobic digestion of perishable organic solid wastes to produce biogas ) 是由 谢冰 汪冰寒 马家莹 王盼亮 苏应龙 于 2019-10-10 设计创作，主要内容包括：本发明公开了一种优化物料组分促进易腐有机固废厌氧消化产沼气的方法,该方法将易腐有机固废中的熟垃圾和生垃圾以不同比例混合,在此基础上添加水稻秸秆进行物料的调配,然后将各组物料置于小型批式厌氧消化装置进行厌氧消化产沼气,当熟垃圾和生垃圾VS比为1：1时,累积产甲烷量相比各自单消化组分别提高了7.8％和26.2％；添加10％的水稻秸秆进一步提高了厌氧消化产甲烷量,相比于单消化组最高提高了36.2％,累积甲烷最大产量达到451ml/g-VS。本发明所述方法简单易行,通过调配易腐有机固废组分促进厌氧产沼气效率,为促进易腐有机固废中但不限于本发明提及的几类有机固体废弃物提供多组分优化方法,不会造成二次污染,为垃圾分类后的湿垃圾及其他易腐有机固废资源化利用提供技术支持。(The invention discloses a method for optimizing material components to promote anaerobic digestion of perishable organic solid wastes to produce biogas, which comprises the steps of mixing cooked garbage and raw garbage in the perishable organic solid wastes according to different proportions, adding rice straws on the basis of mixing the materials, then placing all groups of materials in a small batch anaerobic digestion device for anaerobic digestion to produce biogas, and when the VS ratio of the cooked garbage to the raw garbage is 1: when 1, the accumulated methane yield is respectively improved by 7.8 percent and 26.2 percent compared with the respective single digestion group; the amount of methane produced by anaerobic digestion is further increased by adding 10% of rice straws, compared with a single digestion group, the maximum methane production is increased by 36.2%, and the maximum accumulated methane yield reaches 451 ml/g-VS. The method is simple and easy to implement, the anaerobic biogas production efficiency is promoted by allocating the perishable organic solid waste components, a multi-component optimization method is provided for promoting the perishable organic solid waste but not limiting the organic solid wastes, secondary pollution is avoided, and technical support is provided for resource utilization of the classified wet waste and other perishable organic solid wastes.)

1. A method for promoting the anaerobic digestion of perishable organic solid wastes to produce biogas by blending material components is characterized by comprising the following steps:

(1) preparing raw garbage according to components of kitchen garbage and food market garbage manually, preparing cooked garbage according to components of food market garbage manually, and then treating the raw garbage and the cooked garbage respectively by using a homogenizer to prepare uniform slurry; mechanically crushing the air-dried rice straws; domesticating anaerobic biogas residues in a small anaerobic fermentation tank to obtain an inoculum;

(2) blending the mature garbage, the raw garbage and the rice straw in the step (1) to prepare a fermentation material, then placing the fermentation material and the inoculum in the step (1) in a small batch anaerobic digestion device for anaerobic digestion, and measuring the methane yield every day until the methane yield stops.

2. The method according to claim 1, wherein in the step (1), the components and the mass percentages of the cooked garbage are as follows: 10-30% of rice, 10-30% of noodles, 10-30% of green vegetables, 10-15% of potatoes, 5-10% of bean curd, 5-10% of carrots, 5-10% of pork, 5-10% of chicken, 5-10% of eggs, 0.5-6% of oil and 0.1-3% of salt.

3. The method according to claim 1, wherein in the step (1), the components and the mass percentages of the cooked garbage are as follows: 20% of rice, 10% of noodles, 20% of green vegetables, 15% of potatoes, 6% of bean curd, 5.8% of carrots, 8% of pork, 7% of chicken, 7% of eggs, 1% of oil and 0.2% of salt.

4. The method according to claim 1, wherein in the step (1), the raw garbage comprises the following components in percentage by mass: 30-50% of green vegetables, 5-10% of carrots, 10-20% of potatoes, 10-20% of apples, 10-20% of banana peels and 10-20% of orange peels.

5. The method according to claim 1, wherein in the step (1), the raw garbage comprises the following components in percentage by mass: 30% of green vegetables, 8% of carrots, 12% of potatoes, 20% of apples, 20% of banana peels and 10% of orange peels.

6. The method of claim 1, wherein in step (2), the fermentation material comprises: the adding proportion of the mature garbage and the raw garbage is respectively 10:0, 9:1, 7:3, 5:5, 3:7, 1:9 and 0:10 under the condition of adding 0-20% of rice straws.

7. The method of claim 1, wherein step (2) further comprises unifying the total organic concentration of the fermentation material, as VS; unifying the ratio of the inoculum to the fermentation material; wherein the total VS concentration of the digestion material is 3-12 g/L; the ratio of VS between the inoculum and the digested material is (2-1): (1-2).

8. The method of claim 7, wherein the total VS concentration of the digested material is 3g/L, 6g/L, 12 g/L; the ratio of VS of the inoculum and the digested material was 2: 1,1: 1,1: 2.

Technical Field

The invention belongs to the technical field of environmental ecological energy in environmental science and engineering, and relates to a method for optimizing material components to promote perishable organic solid waste anaerobic digestion to produce biogas.

Background

China has become the first world big country for garbage manufacture beyond the United states since 2004, and the clearing and transporting amount of domestic garbage in cities and towns in China has reached 2.8 hundred million tons in 2017. The sanitary landfill is the mainstream garbage disposal mode at present, two thirds of the more than 600 cities such as Beijing, Shanghai, Guangzhou and the like have faced the severe situation of a 'garbage surrounding city' at present, the stock of the municipal domestic garbage exceeds 80 hundred million tons, and one quarter of the cities have no proper places for stacking the garbage. Incineration is used as another main garbage treatment mode in China to reduce garbage, but due to the fact that the technology of an incineration plant is not perfect, equipment failure is caused due to incomplete garbage classification, and the form problem of an incineration raw material is caused, pollutants such as dioxin, heavy metals and the like in the incineration process and products bring risks to the environment. Biological treatment is the main mode of organic solid waste treatment and resource utilization.

The perishable organic solid wastes (also called wet wastes) are organic solid wastes which are generally called as kitchen wastes, vegetable market wastes and the like and are easy to decay and deteriorate, and can be converted into high-value biomass products after being properly treated. Compared with the resource waste and the environmental pollution caused by landfill and incineration, the anaerobic digestion can carry out efficient resource utilization on the perishable organic solid wastes to generate the biogas and the biogas residues with additional values. The main component of the kitchen waste in the perishable organic solid waste is the residue after meal, and the kitchen waste is cooked waste at high temperature and contains rich grease and protein; kitchen garbage and vegetable market garbage are residues before meals, are raw garbage mainly comprising vegetable stems and vegetable peels, and mainly comprise carbohydrate and cellulose. The raw and cooked garbage has different anaerobic digestion methane production efficiency due to the difference of nutrient components. Anaerobic co-digestion can improve anaerobic biogas production efficiency by reasonable blending of materials and the assistance of other beneficial materials such as agricultural and forestry wastes. Therefore, the optimized co-digestion of the components of the mature garbage and the raw garbage in the easily-rotten organic solid waste can promote the resource utilization of the organic solid waste.

At present, large-scale perishable organic solid waste anaerobic digestion treatment equipment which operates successfully is provided, but the influence of the change of the components on the resource digestion treatment is unknown due to the large change of the feed components. Therefore, the simple and efficient material blending method is a problem to be solved urgently for promoting the anaerobic digestion of the perishable organic solid wastes to produce the biogas.

Disclosure of Invention

The invention aims to provide a method for optimizing material components to promote anaerobic digestion of perishable organic solid wastes to produce biogas, which is simple to operate, saves time and economic cost, is easy to popularize and use, and provides effective technical support for realizing maximization of biogas production efficiency of anaerobic digestion of wet wastes and recycling of perishable organic solid wastes.

In order to achieve the aim, the invention provides a method for optimizing material components to promote the anaerobic digestion of perishable organic solid wastes to produce biogas, which comprises the following steps:

(1) preparing raw garbage according to components of kitchen garbage and food market garbage manually, preparing cooked garbage according to components of food market garbage manually, and then treating the raw garbage and the cooked garbage respectively by using a homogenizer to prepare uniform slurry; mechanically crushing the air-dried rice straws; domesticating the anaerobic biogas residues in a small anaerobic fermentation tank to obtain an inoculum.

(2) Blending the components of the cooked garbage, the raw garbage and the rice straws to prepare a fermentation material, then placing the fermentation material and the inoculum obtained in the step (1) into a small-sized batch anaerobic digestion device for anaerobic digestion, and measuring the biogas production amount every day until the biogas production stops.

In the step (1), the components and mass percentages of the cooked garbage are as follows: 10-30% of rice, 10-30% of noodles, 10-30% of green vegetables, 10-15% of potatoes, 5-10% of bean curd, 5-10% of carrots, 5-10% of pork, 5-10% of chicken, 5-10% of eggs, 0.5-6% of oil and 0.1-3% of salt.

Preferably, the components and mass percentages of the cooked garbage are as follows: 20% of rice, 10% of noodles, 20% of green vegetables, 15% of potatoes, 6% of bean curd, 5.8% of carrots, 8% of pork, 7% of chicken, 7% of eggs, 1% of oil and 0.2% of salt.

In the step (1), the raw garbage comprises the following components in percentage by mass: 30-50% of green vegetables, 5-10% of carrots, 10-20% of potatoes, 10-20% of apples, 10-20% of banana peels and 10-20% of orange peels.

Preferably, the raw garbage comprises the following components in percentage by mass: 30% of green vegetables, 8% of carrots, 12% of potatoes, 20% of apples, 20% of banana peels and 10% of orange peels.

In the step (1), the rice straw can be replaced by agricultural and forestry organic solid wastes such as wheat straw, garden fallen leaves and the like.

The invention has the advantages that the content of organic matters such as carbohydrate, protein, grease, salt and the like in the materials is kept stable, and experimental errors caused by the difference of organic components in actually sampled food waste or kitchen waste can be avoided.

The proportion range of the components in the cooked garbage and the raw garbage is data obtained by performing literature and field investigation on the feeding of a large kitchen garbage anaerobic digestion tank and the types and proportions of food in domestic catering and kitchen garbage, and can reflect the characteristics of the components, so that the method can be applied to an actual perishable organic solid waste anaerobic fermentation device.

In the step (1), the anaerobic biogas residue is dehydrated biogas residue generated after fermentation in a certain large kitchen waste anaerobic digestion treatment plant in Shanghai city. The kitchen waste anaerobic digestion treatment plant adopts a CSTR reactor, the fermentation temperature is 35 ℃, the solid retention time is 30 days, the organic load is 2.5g VS/L/d, the feed is catering and kitchen waste in Shanghai city, and the biogas residue generated by fermentation is subjected to centrifugation, precipitation and dehydration to obtain dehydrated biogas residue.

Further, in the step (1), the acclimation of the inoculum is carried out in a small anaerobic fermentation tank in a working laboratory, the working volume is 5L, the temperature is 37 ℃, the solid retention time is 30 days, the raw garbage and the cooked garbage (VS ratio is 1: 1) are fed, the organic load is 2.5gVS/L/d, and the anaerobic biogas residue used by the method is obtained through 1 year of reaction. The inoculum of the invention has stable components and can not cause qualitative influence on the implementation of the method because of different feed components of the biogas residues of the treatment plant.

The invention utilizes a mechanical crushing method to crush two kinds of perishable organic solid wastes (raw garbage and cooked garbage) and air-dried rice straws.

Wherein, the mechanical crushing method is as follows: and (3) crushing and homogenizing the two kinds of perishable organic solid wastes by using a homogenizer, sieving the crushed and homogenized organic solid wastes by using a 10-mesh sieve, and crushing the rice straws by using a crusher, and sieving the crushed rice straws by using a 40-mesh sieve. The grinding and sieving treatment can ensure that the perishable organic solid wastes are fully contacted with microorganisms in the biogas residues in an anaerobic digestion system, thereby improving the utilization efficiency of the microorganisms to the straws.

In the step (2), the fermentation material comprises the following components: the adding proportion of the mature garbage and the raw garbage is respectively 10:0, 9:1, 7:3, 5:5, 3:7, 1:9 and 0:10 under the condition of adding 0-20% of rice straws.

Step (2) of the invention also comprises the steps of unifying the total organic matter concentration (in VS) of the fermentation material and unifying the proportion of the inoculum to the fermentation material; where VS refers to a volatile solid, it is commonly used to characterize the content of organic substances available for biodegradation.

Wherein the total VS concentration of the digestion material is 3-12 g/L; preferably, 3g/L, 6g/L, 12 g/L; further preferably, it is 6 g/L.

Wherein the ratio of VS between the inoculum and digested material is (2-1): (1-2); preferably, it is 2: 1,1: 1,1: 2; further preferably, is 2: 1.

wherein the aim of unifying the total VS concentration of the anaerobically digested material is to make the results of the methods of the invention comparable. The purpose of optimizing the inoculum addition ratio is to be able to improve the stability of the anaerobic digestion system while providing sufficient methanogenic microorganisms to the system.

In a specific embodiment, the mass ratio of the rice straw, the cooked refuse and the raw refuse is as shown in table 1 below, and preferably, is 0.1: 0.81: a maximum cumulative methane yield of 453ml/gVS was obtained at 0.09.

TABLE 1

Proportion of material addition (based on VS)

The core mechanism of the invention is as follows: under the anaerobic environment, macromolecular organic matters such as starch, protein, lipid and the like contained in raw garbage, cooked garbage and rice straws are firstly decomposed into micromolecular substances by hydrolytic bacteria in the anaerobic digestion process and further degraded into VFAs, and the acetic acid producing bacteria convert the VFAs such as propionic acid, butyric acid and the like into acetic acid and CO₂/H₂Finally, methanogen will mix acetic acid, CO₂/H₂Conversion of iso to CH₄. The main component of the kitchen waste in the perishable organic solid waste is the residue after meal, the kitchen waste is cooked waste at high temperature, and high grease and salt in the kitchen waste can inhibit the metabolism of anaerobic methanogenic microorganisms; kitchen garbage and vegetable market garbage are residues before meals, and are raw garbage mainly comprising vegetable stems and vegetable peels, wherein cellulose is difficult to decompose, so that anaerobic digestion and methane production efficiency are low. The raw garbage and the cooked garbage have different anaerobic digestion methane production efficiency due to the difference of the components, and the digestion of different component materials together can improve the activity of methanogens by balancing the hydrolysis rate of the materials and adjusting C/N. Therefore, the effect of improving the methanogenic efficiency can be achieved by optimizing the perishable organic solid waste anaerobic digestion components.

The innovation point of the invention is that after the component proportion of agricultural and forestry wastes such as cooked garbage, raw garbage, rice straws and the like is adjusted, the small-sized batch anaerobic digestion device is utilized to carry out anaerobic digestion on multi-component materials at the same time to obtain the material additive component with the maximum biogas production amount of unit VS materials, thereby providing effective technical parameters for the anaerobic digestion process and improving the resource recovery efficiency of perishable organic solid wastes.

Compared with the prior art, the invention has the advantages that:

the invention optimizes the raw and cooked components of the easily-rotten organic solid waste and then carries out anaerobic digestion, can improve the biogas yield of unit VS materials, and can make the biogas residues generated after the anaerobic digestion maximally harmless and recyclable in the selection of the materials, which is not thought by the technical personnel in the field.

Among the existing technologies for anaerobic digestion of perishable organic solid wastes, those skilled in the art will readily appreciate that single digestion of food or kitchen waste, random feeding of food and kitchen waste, or co-digestion with the addition of other types of organic solid wastes such as sludge and manure. The single digestion, the mature and the raw garbage are easy to cause the instability and the low efficiency of an anaerobic digestion system, and organic solid wastes such as excrement or sludge contain a large amount of toxic substances and pathogenic bacteria, which is not beneficial to the maximum reclamation of wet garbage and the high-efficiency utilization of equipment.

Drawings

FIG. 1 is a front view of a small-sized batch anaerobic digestion unit according to the present invention.

FIG. 2 is a plan view of a small batch anaerobic digester according to the present invention.

Figure 3 is a graph of pH change during anaerobic digestion for different feed addition groups.

FIG. 4a is a graph of cumulative methane production for single and co-digestion of mature and raw garbage.

FIG. 4b shows the cumulative methane production of the co-digestion of the mature waste and the raw waste with 10% and 20% straw addition.

FIG. 5a is a graph of theoretical and actual maximum methanogenic potential for single and co-digestion of mature and raw garbage

FIG. 5b shows the co-digestion theory and actual maximum methane production potential of the cooked garbage and the raw garbage under the condition of 10% straw addition

FIG. 6 is a graph of perishable organic solid waste multicomponent anaerobic digestion TS removal rates.

FIG. 7 is a flow chart of a method for optimizing material composition to promote anaerobic digestion of perishable organic solid wastes to produce biogas provided by the present invention.

Detailed Description

The invention will be described in further detail with reference to the following specific examples and the accompanying drawings, which are not intended to limit the invention thereto. Variations and advantages that may occur to those skilled in the art may be incorporated into the invention without departing from the spirit and scope of the inventive concept, and the scope of the appended claims is intended to be protected. The procedures, conditions, reagents, experimental methods and the like for carrying out the present invention are general knowledge and common general knowledge in the art except for the contents specifically mentioned below, and the present invention is not particularly limited. The following examples are helpful for understanding the present invention, but do not limit the scope of the present invention.

In the figure 1-2 of the invention, 1-high borosilicate glass tank body, 2-spring net, 3-constant temperature air shaking table, 4-silicone tube and water stop clip, 5-sampling port, 6-aluminum hollow sealing cover and 7-silicone plug.