Thinking about the recycling mode of kitchen waste

Thinking about the recycling mode of kitchen waste under the situation of waste classification

release date: Source: environmental protection

"according to the actual material characteristics, infrastructure supporting conditions, etc., reasonable selection of the recycling mode of perishable waste is an effective guarantee for the successful realization of waste classification and resource conservation." Dai Xin, general manager of the Industrialization Center of Nanjing wandes Environmental Protection Technology Co., Ltd. (hereinafter referred to as "wandes environmental protection"), said at the "2020 (eighth) Shanghai solid waste hotspot forum". At the forum, Dai Xin gave a keynote speech entitled "Discussion on the recycling mode of kitchen waste under the situation of waste classification", sharing some in-depth thoughts on the recycling mode of kitchen waste under the situation of waste classification and the construction of "waste free city"

wandes environmental protection was founded in 2007 and successfully listed on the science and technology innovation board in January 2020. It is committed to becoming an intelligent expert in environmental governance and recycling. Its main businesses include solid waste, water, ecology and intelligent environmental protection, and it specializes in providing advanced environmental protection technology and equipment development, system integration and overall solutions to environmental problems, including R & D and design, equipment integration, engineering contracting, facility operation, etc

the recycling of kitchen waste is the core work of the construction of a "waste free city"

Dai Xin said that under the situation of waste classification, if kitchen waste is burned together with domestic waste, it will bring many problems: first, it will consume the heat energy of incineration; Second, it will produce secondary pollution such as high salt and nitrogen, which will increase the difficulty and cost of treatment. Therefore, in recent years, the state has issued various policies to promote the resource disposal of kitchen waste. The resource disposal of kitchen waste has become the core work of comprehensively implementing waste classification and the construction of "waste free city"

Dai Xin pointed out that before 2017, 46 key cities that implemented waste classification had basically built domestic waste classification and treatment systems. Before entering incineration and landfill facilities, the total recycling rate of recyclable and perishable waste reached more than 35%

taking Shanghai as an example, the data of 2019 show that the perishable garbage accounts for 30%, the recyclable garbage accounts for 20%, and the recycling rate is 35%. If the research and development of biomedical materials are carried out on the premise of "all recyclable wastes are treated as resources", there must be clear utilization goals, which means that more than half of the perishable wastes must be treated as resources before they can meet the corresponding national requirements. According to the statistics of most cities in China, the resource utilization rate of organic waste is less than 20%, and there is a huge demand gap. To solve this problem, we need to choose an economic resource mode and efficient treatment process according to different goals, the characteristics of different cities and the characteristics of materials

three modes of kitchen waste recycling

Dai Xin said that if the domestic waste after classification is treated by anaerobic digestion, the power generation can be increased by more than 10%, which has media reports that it has relatively large resource efficiency. Therefore, anaerobic digestion has become an important technology for the resource utilization of perishable waste because of its high energy conversion rate, stable treatment effect and good economic benefits. However, due to the huge differences in China's regional economic level, living and dietary characteristics, and the construction of supporting facilities, it is difficult to solve the requirements of kitchen waste recycling with different characteristics by using a single technology or process route in the project

Dai Xin believes that in the future, three kitchen waste recycling modes will be widely used:

first, kitchen waste independent treatment mode

the project of kitchen waste independent treatment mode requires a high utilization rate of resources, and requires that the whole system can adapt to the changes in material characteristics in the process of waste classification

in the independent treatment mode of kitchen waste, the widely used treatment processes are "wet anaerobic" and "dry anaerobic". Among them, the advantages of wet anaerobic are low project investment and operation cost, stable process and many operation cases. At the same time, it also has some disadvantages, such as high requirements for incoming material quality, including pretreatment system and stability, and high solid content materials need to be diluted with water, And the need to increase the treatment capacity and scale of biogas slurry

the dry anaerobic process has the advantages of good material compatibility and high organic load. At the same time, it also has the disadvantages of high investment and operation cost, complex biogas residue dehydration process, less domestic operation projects and so on

based on these comparative analysis, Dai Xin believes that there will be two different operation ways for the independent treatment mode of kitchen waste in the future: first, when the classification work is done well, the content of impurities in materials is low, the thickness difference of 3 test pieces is high, and it is suitable for the wet anaerobic process, which will produce great economic advantages; Second, when the moisture content of materials is relatively low and the solid content is relatively high, dry anaerobic is simpler and more effective. At the same time, if it involves the collaborative disposal of garden and greening waste, dry anaerobic also has very obvious advantages

second, we can provide solutions along the whole process chain, kitchen waste and kitchen collaborative processing mode

the requirements of kitchen waste and kitchen collaborative processing mode for the project are good compatibility of kitchen and kitchen waste materials, and full consideration should be given to functional collaboration between subsystems. There are two process routes, "wet anaerobic" and "wet + dry anaerobic"

the wet anaerobic process is suitable for raw materials with large proportion of kitchen waste and low solid content, which can achieve a more economic effect

wet Anaerobic + dry anaerobic process is suitable for raw materials with a large proportion of kitchen waste and high solid content. Dai Xin pointed out that the biogas residue generated in the pretreatment process can be incorporated into the dry anaerobic system to further improve the utilization of organic matter and generate higher benefits

III. kitchen waste incineration collaborative mode

in Dai Xin's view, by contrast, the kitchen waste incineration collaborative mode will be more competitive in the future. In this mode, biogas utilization and incineration power generation work together efficiently to maximize the benefits of resources. Adopting pretreatment + wet anaerobic process can save the cost of transporting and disposing residues and biogas residues, and can also save the construction and operation cost of biogas utilization equipment

at the same time, Dai Xin pointed out that the advantages of the incineration collaborative project lie in the sharing of heat sources and the saving of system operation costs; Impurities and biogas residues are treated nearby to save transportation costs; Odor treatment system is shared, saving equipment investment; Public utilities, saving civil engineering costs. Through the embodiment of these advantages, 20% - 30% of equipment investment can be saved. At the same time, the sharing of some process sheets can form a scale effect and reduce the operation cost

Dai Xin concluded that the reasonable selection of corresponding modes such as the recycling of perishable waste according to the characteristics of different materials and the supporting conditions of infrastructure is an effective guarantee for the successful realization of waste classification and resource conservation

biogas slurry full quantitative treatment technology

Dai Xin introduced that the biogas slurry treatment technology of wandes environmental protection is a very important technology sheet that affects the operation of organic waste treatment. Wandes environmental protection has comprehensive technical reserves and rich performance experience

at the same time, the concentrated liquid treatment technology of wandes environmental protection is also very comprehensive, including coagulation/air flotation + advanced oxidation, DTRO reduction, material film reduction, pretreatment +mvr evaporation, dtro+mvr evaporation and many other technical lists, with engineering application cases, which can meet various emission standards

nowadays, the business scope of wandes environmental protection has covered the whole country and has overseas performance experience. From 2017 to 2019, wandes environmental protection continued to achieve a high compound revenue growth rate, with a variety of types and rich experience in project operation and management

in terms of business model, wandes environmental protection is committed to forming a technical system, becoming a system integrated solution provider, and providing process equipment and operation services for the whole chain of organic solid wastes (pretreatment, anaerobic, biogas slurry, etc.). The business model includes investment (BOT, etc.), general contracting (EPC), equipment supply and complete set, custody operation

finally, Dai Xin said, "wandes environmental sincerely hopes to cooperate in depth with its peers and jointly contribute to China's pre classification work."