Discussion on kitchen waste treatment mode based on dry wet separation pretreatment

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Waste classification is a very important work, which is related to the effectiveness of national environmental protection and the process of social civilization. Since 2000, China has started to imple

 Analysis of kitchen waste treatment mode
1. Biochemical processor processing technology based on Community
This technology refers to a fast organic waste composter equipped with efficient bacteria in the community and can control the composting conditions. It is used for centralized composting of kitchen waste. This model has the advantages of resource and reduction. In recent years, with the continuous improvement of the classification and treatment technology level of kitchen waste in China, some biotechnology companies began to make great efforts in waste treatment and developed biochemical processor equipment related to kitchen waste. These equipment can quickly degrade kitchen waste into organic products with low moisture content by fermenting microorganisms with the help of high temperature. After treatment, these products can become semi fermented organic fertilizer and feed additives. Compared with the traditional composting system, this waste treatment technology can treat the kitchen waste nearby, which can reduce the secondary pollution during transportation or stacking, shorten the transportation distance and reduce the transportation cost. However, this kind of equipment faces the defect of large one-time investment. Compared with the traditional treatment method, its investment is higher than three times or even higher, and the setting of biochemical treatment machine takes up a certain area. The application of this method in areas with valuable land resources and high-rise buildings will be limited. In addition, it is also necessary to consider the adaptability of strains and pay attention to the maintenance of their stability.
2. Household based kitchen waste shredder treatment mode
The shredder treatment mode is an important mode of kitchen waste treatment. It can directly crush and crush the kitchen waste, wash it with the help of hydraulic power, discharge the wastewater into the municipal sewer network, and combine it with the sewage in the city, so as to enter the sewage treatment for centralized treatment. The United States developed the household waste crusher in 1927 and improved and popularized it in 1940, which solved the problem of food waste storage in many residents' homes. In 2001, the kitchen waste crusher was included in the key development projects of residential decoration in China. Later, the Ministry of construction launched the science and technology residential demonstration project, in which the household kitchen waste crusher was included in the supporting promotion of modern kitchen, and made a demonstration and display. In recent years, the popularity of household crushers in China has been increasing. However, this waste treatment mode also has some defects. For example, when the crushed kitchen waste enters the urban sewage pipe network, it is easy to block, so it is necessary to expand the official website or reserve space. Moreover, the integration of kitchen waste and urban sewage after crushing will lead to the rapid increase of BOD and COD in sewage, which will lead to greater working pressure for the sewage treatment department, so this model is not suitable for large-scale application.
2、 Selection of kitchen waste treatment mode based on dry wet separation pretreatment
Kitchen waste accounts for more than 50% of the total domestic waste. The extensive treatment method of treating it as mixed waste is easy to bring environmental and social problems. Classified collection and scientific treatment methods can reduce waste, rationalize resources and make waste harmless. It is an effective way to treat kitchen waste based on dry wet separation pretreatment. In the process of using this waste treatment method, three problems need to be considered: first, whether the sorted kitchen waste is treated centrally at the end or dispersed at the source; Second, what kind of technology needs to be used in the process of treatment. Assuming that after the above analysis, it is decided to select the source treatment method, it is necessary to choose whether to use the pulverizer with the family as the unit or the biochemical processor with the community as the unit. Assuming that the end treatment is selected after the above analysis, it is necessary to clarify whether to use incineration, composting or landfill; Third, if the end treatment method is selected on the second issue, the corresponding layout scheme and facilities and equipment should be considered.
1. Compare end treatment schemes
In the end treatment of kitchen waste, pretreatment and no pretreatment can be adopted. Pretreatment can reduce the moisture content of kitchen waste. Pressing is an important way in pretreatment, which has good prospects and great advantages. The solid and liquid of kitchen waste need to be treated separately by pressing technology, which has the characteristics of high environmental protection performance and high resource utilization rate, but the process is cumbersome. If the pressing technology is not used, some cow dung, branches and leaves can be added to the kitchen waste to adjust the moisture content, and then compost at high temperature. This method is simple to operate and easy to manage, but it needs to prepare enough cow dung, branches and other auxiliary materials. To sum up, four highly operational and comprehensive kitchen waste treatment modes are designed:
First, the original kitchen waste + dry material mixed high-temperature composting mode. For kitchen waste without pretreatment, it is directly transported to the composting yard. The moisture content of mixed auxiliary materials is adjusted appropriately, and then it is composted at high temperature. Compost products can be used as fertilizer for resource utilization and give full play to its role.
Second, press pretreatment + aerobic composting of dry components + anaerobic digestion of wet components to produce gas. Dry component: carry out aerobic composting with composting raw materials. Because there is no high moisture content in raw materials, they can be used for composting without adjustment, which promotes the scientific application of resources and improves the overall economic benefits. After aerobic composting, the residue can also be landfilled. Wet components: enter the anaerobic fermentation tank with the help of pipes and pumps, and then produce biogas. After the fermentation of wet components, many solids can be consumed, so part of the residue can be made into fertilizer, which can be treated and used as resources.
Third, press pretreatment + dry component incineration power generation + wet component anaerobic digestion gas production. Dry component: if the calorific value is above 8000kj / kg, it will be stored in the fuel storage pit as power generation fuel. After incineration, the residue will be treated by landfill. Wet component: the treatment method is the same as the above wet component.
Fourth, press pretreatment + dry component sanitary landfill + wet component anaerobic digestion for gas production. Dry components: directly transported to the landfill for treatment. Because the volume of dry components is greatly reduced after pressing, it will not occupy too much storage capacity in the process of sanitary landfill. Wet component: the same treatment as above.
Of course, there are not only these four modes of kitchen waste treatment, but also other modes, such as incineration or landfill of classified kitchen waste. Technically, this method is also feasible, but its high water content can easily lead to more seepage in landfill, or hinder incineration conditions, so it will lead to economic and technical problems. Based on this, the above four schemes are formulated. Different cities can choose targeted kitchen waste treatment schemes according to the actual situation.
2. Compare the source treatment scheme with the end treatment scheme
Source treatment mainly refers to household shredder treatment and community biochemical processor treatment. This treatment method can treat kitchen waste nearby, achieve reduction effect and save transportation cost. End treatment mainly refers to aerobic composting treatment, incineration treatment or landfill treatment. Among these treatment methods, pressing technology is the main pretreatment technology. The first step is to separate kitchen waste from domestic waste, and then carry out pretreatment of kitchen waste according to the traditional waste treatment process, followed by harmless, resource-based and reduction treatment.
Because the treatment technology of household crusher has high requirements for kitchen drainage pipeline and space, and the daily operation requires high maintenance cost and high one-time investment cost, many cities in China are not suitable to use this mode. The community biochemical processor has high requirements for the moisture and organic matter of raw materials, and needs to be equipped with professional operators in each community. In addition, the investment cost is high, so it is not suitable for many cities. In conclusion, it is considered that the end treatment method of kitchen waste should be selected for intensive treatment.
3、 Conclusion
From the perspective of dry wet separation pretreatment, the classified treatment of kitchen waste has great practical significance, which is very beneficial to improve the treatment effect of kitchen waste and protect the environment. Based on this, this paper designs several kitchen waste treatment modes, hoping to provide some reference for relevant personnel.
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