CN110586607B

CN110586607B - Household garbage treatment method

Info

Publication number: CN110586607B
Application number: CN201810605269.0A
Authority: CN
Inventors: 贾书亚
Original assignee: Zhongyuan Environmental Technology Co ltd
Current assignee: Zhongyuan Environmental Technology Co ltd
Priority date: 2018-06-13
Filing date: 2018-06-13
Publication date: 2021-08-17
Anticipated expiration: 2038-06-13
Also published as: CN110586607A

Abstract

The invention relates to the technical field of solid waste treatment, in particular to a domestic waste treatment method, which comprises the following steps of firstly, crushing, sorting, grinding and screening domestic waste to be treated; then adjusting the solid content of the fermented material to be 3-8%, introducing micron bubbles, floating the finely-crushed material with light specific gravity under the action of the micron bubbles, rapidly settling the mud sand and metal particle type material with high specific gravity, suspending non-rotten organic matters in the middle, and realizing rapid and thorough separation of four phases of the light material, the non-rotten organic matters, biogas slurry and the mud sand, wherein the content of the mud sand in the non-rotten organic matters is lower than 2%, and decomposing to prepare an organic fertilizer with fixed quality; the water content in the separated mud and sand is lower than 20%, the organic matter content is lower than 0.5%, the direct landfill treatment can be carried out, and the problem that the mud and sand type materials or other materials which are difficult to degrade and generated in the process of treating the garbage in the conventional fermentation mode are too much and cannot be directly buried is solved.

Description

Household garbage treatment method

Technical Field

The invention relates to the technical field of solid waste treatment, in particular to a domestic waste treatment method.

Background

With the progress of human civilization, the requirement on environmental cleanliness is higher and higher, and the concept of environmental protection development is acknowledged. After the rapid development of decades, the ecological environment of China is damaged a lot. The eighteenth of the parties, the environmental protection supervision is continuously increased, and the reduction, the classified collection, the resource utilization and the creation of the circular sustainable development ecological economy become national policies.

The general classification method of the domestic garbage is that dry-wet classification is firstly carried out, and garbage with low moisture content, such as plastics, fabrics, rubber, paper, bamboo and wood, is taken as a class and is called dry garbage; garbage with high water content such as vegetable residue, rice residue, pericarp, and fruit stone in kitchen is called wet garbage. The dry garbage is generally sent to be utilized for energy utilization (such as incineration or gasification power generation) or to be converted for energy (such as oil and carbon production by pyrolysis); however, practice of decades proves that the mixing property and classification incompleteness of the garbage determine that the nutrient component fluctuation of the product of the perishable garbage direct compost is large, the heavy metal content uncertainty is strong, and the product is difficult to be used as a product with stable quality, so that a domestic garbage treatment company mainly treating the compost is basically closed, and the state also has a policy, and the garbage derived fertilizer is not allowed to enter food chain production. In order to improve the stability of the product after the fermentation treatment of the perishable garbage, indexes influencing the quality of the final product must be controlled in each process such as pretreatment, fermentation process, product post-treatment and the like, and systematic, scientific and reasonable process design is required.

With the implementation of the national garbage classification policy, the treatment of kitchen garbage, garbage of the professional markets of vegetables and fruits, and garbage rich in perishable organic matters such as livestock and poultry breeding wastes and the like can be highlighted to become a civil and environmental problem. The garbage has high water content (usually 60-90%), is mixed with difficult-to-rot and large organic matters such as plastics, fabrics, paper, bamboo and wood, inorganic inert substances such as silt, stones, cement blocks and glass, and metal such as bottle caps, and is difficult to realize thorough separation by common mechanical equipment. Such wet waste is not suitable for landfill, has no land landfill, cannot be directly incinerated, and cannot be directly fermented for composting. Partial resource conversion can be realized by utilizing wet anaerobic process, but the operation stability, the economy and the sustainability are not good due to high investment and lack of effective pretreatment. If dry anaerobic fermentation is adopted, due to the mixed bulk winding property and hard substances, the system process control difficulty is high, the methane yield is unstable, the system process is easy to collapse due to acidification, the failure rate of system equipment is high, and the long-term stable operation is difficult.

In addition, for the individual treatment of a certain perishable waste, the system scale, the input-output ratio, the construction of an environmental protection auxiliary system, the destination of byproducts and the like are inevitable practical problems, and become a bottleneck limiting the treatment of the perishable waste. For example, for a kitchen waste treatment project, anaerobic fermentation only converts part of perishable organic matters in the kitchen waste into biogas, so that energy utilization is performed, the separated impurities comprise metal, glass, paper, bamboo, plastic and the like, and biogas residues and biogas slurry after anaerobic fermentation cannot be well treated. In addition, no matter dry anaerobic fermentation or wet anaerobic fermentation, due to the improper material pretreatment process and the treatment process of the fermented product at present, the lasting, safe and efficient operation in the fermentation process cannot be maintained in industrial application. Therefore, innovative research needs to be carried out on the pretreatment process of the fermentation of the materials and the treatment process of the fermented biogas residues and biogas slurry so as to form a scientific, systematic and efficient domestic garbage treatment process.

For example, patent CN107511389A discloses a hydraulic sorting and pulping process and treatment system for domestic garbage, which discloses a sorting treatment method before fermentation of domestic garbage, but in the method, the bag breaking rate of bag breaking sorting by using a roller screening and bag breaking machine is low, wet materials which are not easy to break by rollers can not be broken well and can not be directly removed, and perishable organic matters and difficultly rotten metals or plastic products can not be well separated. In addition, although a process method of garbage pretreatment for producing biogas slurry by anaerobic fermentation exists in the prior art, biogas slurry is also used in a backflow mode in the treatment process of fermented biogas residues and biogas slurry, at present, the separation of components of fermented materials is not thorough, a large amount of impurities such as silt and the like in non-rotten organic matters are not easy to be directly used for subsequent rotten production, and direct landfill cannot be achieved due to high organic matter content.

Therefore, improvement and innovation are needed for the pre-fermentation treatment mode and the material separation mode after fermentation of the household garbage treatment system, so as to improve the economic benefit of household garbage treatment, effectively utilize resources to the maximum extent and reduce secondary pollution emission.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a domestic garbage treatment method, which is used for realizing proper pretreatment of domestic garbage rich in perishable organic matters, thoroughly separating specific gravity light substances, hardly rotten organic matters, silt and sand substances and biogas slurry in fermented materials, maximally utilizing effective resources for the second time, realizing recycling of the biogas slurry and reducing secondary pollution discharge.

In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:

a household garbage treatment method comprises the following operation steps:

1) crushing, sorting, grinding and screening the household garbage to be treated;

2) adjusting the solid content of the garbage obtained by screening in the step 1) by using water, and performing anaerobic fermentation treatment;

3) adding water into the material after the anaerobic fermentation in the step 2) to adjust the solid content to obtain slurry; the micron bubbles are continuously introduced into the slurry, materials with light specific gravity in the slurry quickly float upwards under the action of the micron bubbles, mud and sand materials with high specific gravity are settled, and non-corrosive organic matters are suspended in the middle; removing the floating material on the upper layer and the settled material on the lower layer to obtain slurry containing the difficultly rotten organic matters;

4) flocculating, settling and filter-pressing the slurry containing the non-rotten organic matters obtained in the step 3) to obtain biogas slurry and the non-rotten organic matters.

Optionally, water is used in the step 2) to adjust the solid content of the garbage obtained by screening in the step 1) to be 15-40%. Further preferably, water is adopted in the step 2) to adjust the solid content of the garbage obtained by screening in the step 1) to be 25-35%.

Optionally, in the step 3), water is added into the material after the anaerobic fermentation in the step 2) is completed to adjust the solid content to 3% -8%. Further preferably, in the step 3), water is added into the material after the anaerobic fermentation in the step 2) is finished to adjust the solid content to 5%.

Optionally, the household garbage comprises kitchen garbage, fruits and vegetables and other professional market wastes.

Optionally, the domestic waste is organic perishable waste.

Optionally, the biogas slurry obtained in the step 4) is refluxed to the step 2) and/or the step 3) to be used as a water source.

Optionally, controlling the ammonia nitrogen content of the biogas slurry refluxed to the step 2) to be lower than 1800 mg/L.

The biogas slurry obtained in the step 4) can be recycled by refluxing, and can be applied to all operation steps requiring water in the whole treatment method by refluxing in the actual operation process, for example, large articles, soft plastics, fabrics, rubber and other articles selected by cleaning can be cleaned by the biogas slurry, the enrichment amount of the biogas slurry can be controlled according to the reflux use amount of the biogas slurry in each operation step in the biogas slurry reflux use process, so that the full-amount reflux utilization of the biogas slurry in the whole system method is realized, under the condition that the moisture content in the household garbage to be treated is lower than 45%, the whole system can be free from generating redundant biogas slurry, the biogas slurry does not need to be discharged and treated, and the secondary pollution caused by biogas slurry discharge is avoided; in addition, controlling the ammonia nitrogen content of the biogas slurry reflowing to the step 2), and performing deodorization and ammonia nitrogen treatment on the biogas slurry when necessary, so as to avoid the influence of ammonia nitrogen in the biogas slurry on the fermentation process.

Optionally, in the step 1), the household garbage to be treated is subjected to crushing, sorting, grinding and screening treatment; the specific method comprises the following steps: firstly, carrying out primary crushing treatment on household garbage to be treated, selecting and removing uncrushed large articles, soft plastics, fabrics, rubber and high-strength metal, and carrying out screening treatment to obtain garbage below 80 mm; and grinding the garbage with the size of less than 80mm obtained by screening, only crushing perishable organic matters and partial brittle and hard inorganic matters, and screening to obtain the garbage with the size of less than 12 mm.

For domestic garbage in China, after large materials are manually selected and sieved by a roller, only the bag breaking rate of not more than 85% can be realized, and the rest 15% of bags cannot be broken, so that the sieving effect, the organic matter extraction rate and the final biogas yield are seriously influenced, and the effect difference is large. The invention combines the matching treatment of full bag breaking, mechanical crushing and grinding, firstly grinds and crushes materials which are enriched with perishable organic matters such as meal, vegetable, leaves and grass, crushes and grinds the perishable organic matters and hard and brittle inorganic matters to realize uniform particle size, and can ensure the smooth realization of organic matter extraction and high separation efficiency and better separation effect. Meanwhile, the obtained garbage materials for anaerobic fermentation do not contain large light materials with winding property, so that the flowability of the fermented materials is improved, the fermented materials are easy to uniformly mix, the control of an anaerobic process is facilitated, the volume of an anaerobic fermentation tank and the performance requirement of stirring equipment are greatly reduced, the equipment investment of an anaerobic system is reduced, and the operation stability of the process and the system is improved.

Optionally, recycling biogas generated by anaerobic fermentation in the step 2); directly performing landfill treatment on the lower-layer settled material removed in the step 3); the non-rotten organic matters obtained in the step 4) are further decomposed to be used as raw materials of the organic fertilizer.

The anaerobic fermentation process in the step 2) of the invention adopts the existing anaerobic fermentation process to carry out anaerobic fermentation, and the differences are solid content of the materials before the anaerobic fermentation and post-treatment of the materials after the anaerobic fermentation.

The household garbage treatment method comprises the steps of crushing and grinding household garbage to be treated to a particle size of less than 12mm for fermentation treatment, adding a large amount of water into the fermented material to adjust the solid content of the material, introducing micron bubbles, floating the finely-crushed material with a light specific gravity under the action of the micron bubbles, settling silt and metal particle materials with a large specific gravity, suspending non-rotten organic matters in the middle, and realizing the rapid and thorough separation of four phases of the light material, the non-rotten organic matters, biogas slurry and the silt, wherein the content of the silt in the finally-separated non-rotten organic matters is lower than 2%, so that the content of impurities in the non-rotten organic matters is low, and the organic fertilizer raw material with stable quality can be prepared by further rotting treatment; the water content in the separated mud and sand is lower than 20%, the organic matter content is lower than 0.5%, the direct landfill treatment can be carried out, and the problem that the mud and sand type materials or other materials which are difficult to degrade and generated in the process of treating the garbage in the conventional fermentation mode are too much and cannot be directly buried is solved.

Detailed Description

The technical solution of the present invention will be described in detail by specific examples.

The household garbage treated by the following embodiment comprises organic perishable garbage such as kitchen garbage, fruit and vegetable and other professional market wastes.

In the following embodiment, when the material after the anaerobic fermentation is separated in step 3), the slurry with the regulated solid content can be added into a flotation tank, a micron bubble generator is arranged at the lower part of the flotation tank, a liquid discharge port is arranged at the middle part of the flotation tank, a sand discharging mechanism is arranged at the bottom part of the flotation tank, the material with light specific gravity floating on the upper part of the flotation tank can be scraped by adopting a scraping structure, and the settled sand material at the lower layer can be discharged from a sand discharge port arranged at the bottom part of the flotation tank through a screw feeding mechanism.

Examples

A household garbage treatment method comprises the following operation steps:

1) firstly, carrying out primary crushing treatment on household garbage to be treated, selecting and removing uncrushed large articles, metal, plastic, fiber light substances and other hard-to-crush articles, and carrying out screening treatment to obtain garbage below 80 mm; grinding the garbage below 80mm obtained by screening, only crushing perishable organic matters and partial brittle, hard and breakable inorganic matters, and screening to obtain garbage below 12 mm;

2) adjusting the solid content of the garbage obtained by screening in the step 1) to be 30% by adopting water, carrying out anaerobic fermentation treatment, and recycling methane generated in the anaerobic fermentation process;

3) adding water into the material after the anaerobic fermentation in the step 2) to adjust the solid content to 5 percent to obtain slurry; micron bubbles are continuously introduced into the slurry, materials with light specific gravity in the slurry quickly float upwards under the action of the micron bubbles, mud and sand materials with high specific gravity are settled, and non-corrosive organic matters are suspended in the middle; removing the floating material on the upper layer and the settled material on the lower layer to obtain slurry containing non-rotten organic matters;

In the process of treating the domestic garbage by forming a complete system by adopting the domestic garbage treatment method in the embodiment, the biogas slurry obtained in the step 4) can be refluxed to the step 2) and/or the step 3) to be used as a water source, the generation of foul smell caused by continuous enrichment and reflux of the biogas slurry is reduced in order to avoid the influence of ammonia nitrogen in the biogas slurry on the fermentation process, when the garbage treatment system is formed by adopting the method in the embodiment, the reflux biogas slurry is periodically subjected to deodorization treatment, and meanwhile, the ammonia nitrogen content of the biogas slurry refluxed to the step 2) is controlled to be lower than 1800 mg/L;

in addition, the purpose of adjusting the solid content in the step 2) in the process of treating the domestic garbage by using the treatment method of the embodiment is to meet the solid content requirement of dry anaerobic fermentation, and the solid content is generally adjusted to be 15-40%, preferably 25-35%; in the step 3), the solid content of the fermented material is adjusted, the solid content of the fermented material can be reduced by adopting a large proportion of backflow biogas slurry, various separation efficiencies and separation qualities of the fermented material are improved, and the solid content is generally required to be controlled to be 3% -8%, preferably 5%.

Comparative example 1

The difference between the comparative example and the example is that only crushing treatment and screening are carried out in the treatment process of the household garbage to be treated in the step 1) to obtain garbage with the size of less than 80mm, and no further grinding treatment is carried out.

Comparative example 2

The comparative example is different from the examples in that the micron bubbles are not introduced in the step 3), and air bubbles are blown instead.

Comparative example 3

The difference between the comparative example and the example is that micron bubbles are not introduced in the step 3), and the slurry with the adjusted solid content is subjected to natural sedimentation treatment.

Comparative example 4

The comparative example differs from the example in that the solids content of the material after anaerobic fermentation in step 3) was adjusted to 10%, and the other examples are the same.

Comparative example 5

The comparative example differs from the example in that the solids content of the material after anaerobic fermentation in step 3) was adjusted to 15%, and the other examples are the same.

Comparative example 6

The comparative example differs from the example in that the solid content of the material after anaerobic fermentation in step 3) was adjusted to 2%, and the other examples are the same.

Comparative example 7

The comparative example differs from the example in that the solid content of the material after anaerobic fermentation in step 3) was adjusted to 1%, and the other examples are the same.

And (3) effect comparison:

the content and the moisture content of the non-corrosive organic matters in the non-corrosive organic matters obtained by the treatment methods of the examples and the comparative examples 1 to 7 are respectively detected, and the results of the content and the moisture content of the non-corrosive organic matters in the obtained sludge materials are shown in the following table 1:

TABLE 1

As can be seen from the results shown in table 1, compared with comparative example 1, comparative example 2 and comparative example 3, the treatment method according to the embodiment of the present invention has a low content of silt-like materials in non-decomposed organic matters (biogas residues) after separation treatment of fermented materials, and can directly perform further decomposition treatment to obtain organic fertilizer raw materials with stable quality meeting requirements, improve the resource utilization rate of garbage, and avoid secondary pollution caused by biogas residue discharge or decomposed products; the obtained silt material has low content of non-corrosive organic matters, meets the requirement of direct landfill, and does not cause secondary pollution to soil and the like; can also be directly used as the raw material for producing sintered bricks and building ceramsite. The comparative results of the embodiment and the comparative example 1 show that the treatment before the fermentation of the household garbage can affect the separation of the components of the material after the subsequent fermentation, and the invention can grind the material, improve the uniformity of material particles, and improve the separation efficiency and the separation thoroughness; the comparison results of the embodiment and the comparative examples 2 and 3 show that the separation method of introducing the micro bubbles is adopted, the material separation speed is increased, the separation efficiency is improved, the components in the fermented material can be thoroughly separated, the separated material can be directly recycled, and the comparative example 3 cannot completely separate the fermented material with the same volume by adopting the traditional flocculation sedimentation. It can be seen that the present invention utilizes the introduction of micro bubbles to achieve the importance of post-treatment of the fermentation product.

In addition, as can be seen from the data of comparative examples 4 to 7, in the process of separating the fermented material, adjusting the solid content of the fermented material to be too high affects the separation efficiency and the product quality, so that the content of the separated non-rotten organic matters in the silt is increased, and the content of the non-rotten organic matters in the separated silt is increased. The non-rotten organic matters can not produce high-quality organic fertilizers, and the silt can not be directly buried, so that the organic matters need to be further separated and removed. The solid content of the fermented materials is reduced, the separation quality of the materials of each phase can be improved, but the low solid content needs to be adjusted by adding more water, so that more biogas slurry needs to be enriched when the backflow biogas slurry is used as a water source for adjusting the solid content, the burden of continuous operation of the system is too heavy, and the operation cost is increased. Therefore, by comparing the practical results of the embodiment and the comparative examples 4-7, the invention creatively selects the appropriate solid content to be adjusted when the fermented material is separated, meets the quality of each phase separation of the material, ensures that no redundant biogas slurry is generated in the system under the condition that the moisture content of the treated household garbage is lower than 45%, realizes the full-scale backflow of the biogas slurry, reduces the system pressure of biogas slurry treatment, and improves the economic benefit of the system and the utilization rate of organic matters.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. The household garbage treatment method is characterized by comprising the following operation steps:

3) adding water into the material after the anaerobic fermentation in the step 2) to adjust the solid content to obtain slurry; continuously introducing micro bubbles into the slurry, floating materials with light specific gravity in the slurry under the action of the micro bubbles, settling mud and sand materials with high specific gravity, and suspending non-corrosive organic matters in the middle; removing the floating material on the upper layer and the settled material on the lower layer to obtain slurry containing the difficultly rotten organic matters;

4) flocculating, settling and filter-pressing the slurry containing the non-corrosive organic matters obtained in the step 3) to obtain biogas slurry and non-corrosive organic matters.

2. The method for treating household garbage according to claim 1, wherein the household garbage comprises kitchen garbage and fruit and vegetable professional market waste.

3. The method according to claim 2, wherein the household waste is a waste rich in organic perishable waste.

4. The method for treating household garbage according to claim 1, wherein the biogas slurry obtained in the step 4) is refluxed to the step 2) and/or the step 3) to be used as a water source.

5. The household garbage treatment method as claimed in claim 4, wherein the ammonia nitrogen content of the biogas slurry refluxed to the step 2) is controlled to be lower than 1800 mg/L.

6. The household garbage disposal method according to claim 1, wherein the specific method for crushing, sorting, grinding and screening the household garbage to be disposed in the step 1) comprises the following steps: firstly, carrying out primary crushing treatment on household garbage to be treated, selecting and removing uncrushed large articles, and carrying out screening treatment to obtain garbage below 80 mm; and then grinding the garbage below 80mm obtained by screening, and screening to obtain the garbage below 12 mm.

7. The method for treating household garbage according to claim 1, wherein the biogas generated by anaerobic fermentation in step 2) is recycled; directly performing landfill treatment on the lower-layer settled material removed in the step 3); and 4) further decomposing the non-decomposed organic matters obtained in the step 4) to obtain organic fertilizer raw materials.

8. The domestic waste treatment method according to claim 1, wherein the solid content of the waste obtained by screening in step 1) is adjusted to 15% to 40% by using water in step 2).

9. The domestic waste treatment method according to claim 1, wherein in step 3), water is added to the material after completion of the anaerobic fermentation in step 2) to adjust the solid content to 3% to 8%.