1. Overview of waste generation and treatment in my country:
The compilation team of the Ministry of Environmental Protection's "Technical Standards for Environmental Protection Acceptance of Completion of Construction Projects Domestic Waste Landfill Projects" recently confirmed that: about 2/ 3% of large and medium-sized cities are currently surrounded by garbage, and about 1/4 of the cities have no suitable place to pile garbage. Statistics show that in recent years, with the acceleration of urbanization and the improvement of people's living standards, my country's urban domestic waste has grown at an average annual rate of nearly 9%, with the per capita annual domestic waste production reaching 440kg. In cities such as Beijing, the increase has been as high as 15%-20%. At present, my country's urban domestic waste generation is about 146 million tons, and the cumulative amount of urban waste accumulated is more than 7 billion tons, covering an area of ??more than 500 million square meters.
Data from the 2013 China Statistical Yearbook: By the end of 2012, there were 540 landfills nationwide, with a landfill capacity of 311,000 tons per day, and the total landfill volume for the year was 105.125 million tons. . About 72.6% of municipal solid waste is disposed of in landfills.
The main environmental impacts caused by the landfill treatment of domestic waste include the unique odorous gas pollution emitted by the garbage, the landfill gas pollution generated by the degradation and fermentation of the garbage during the landfill process, and the physical impact of the landfill and landfill processes. Leachate pollution with high concentration of pollutants produced by , chemical and biological effects, rainwater leaching, scouring, and groundwater immersion, pollution caused by the concentration of flies caused by the stench of the landfill, etc. Landfill technology, as the traditional treatment and final treatment method of domestic waste, is still the main way to dispose of domestic waste in my country and most countries in the world. The overall level of domestic waste landfill in my country is still in its initial stage.
2. Principles of comprehensive waste management:
Adapt measures to local conditions and provide scientific guidance. Consider the actual situation in different regions, strengthen classified guidance, and adhere to the combination of centralized processing and decentralized processing. In accordance with the principles of "reduction, resource utilization, and harmlessness", advanced and applicable technologies should be selected according to local conditions. Areas with favorable conditions should give priority to incineration and other resource treatment technologies.
China’s domestic waste can generally be divided into four major categories: recyclable waste, food waste, hazardous waste and other waste. Currently commonly used garbage disposal methods include: comprehensive utilization, sanitary landfill, incineration and composting.
1. Recyclable garbage mainly includes five categories: waste paper, plastic, glass, metal and cloth.
1) Waste paper: mainly includes newspapers, periodicals, books, various packaging papers, office paper, advertising paper, cartons, etc. However, it should be noted that paper towels and toilet paper cannot be recycled due to their strong water solubility. Recycle.
2) Plastics: mainly include various plastic bags, plastic packaging, disposable plastic lunch boxes and tableware, toothbrushes, cups, mineral water bottles, toothpaste wrappers, etc.
3) Glass: mainly includes various glass bottles, broken glass pieces, mirrors, light bulbs, thermos bottles, etc.
4) Metal objects: mainly include cans, cans, etc.
5) Fabrics: mainly include discarded clothes, tablecloths, washcloths, school bags, shoes, etc.
Through comprehensive treatment and recycling, pollution can be reduced and resources saved. For example, every ton of waste paper recycled can make 850 kilograms of good paper, save 300 kilograms of wood, and reduce pollution by 74% compared with the same amount of production; every ton of plastic beverage bottles recycled can obtain 0.7 tons of secondary raw materials; every ton of scrap steel can be recycled Smelting 0.9 tons of steel, saving 47% of the cost compared with ore smelting, reducing air pollution by 75%, and reducing water pollution and solid waste by 97%.
2. Kitchen waste includes: leftovers, bones, roots, leaves, peels and other food waste. After biotechnology treatment, each ton can produce 0.3 tons of organic fertilizer.
3. Hazardous waste includes: waste batteries, waste fluorescent tubes, waste mercury thermometers, expired medicines, etc. These wastes require special safe handling.
4. Other waste includes: in addition to the above categories of waste, bricks, ceramics, slag, toilet paper, paper towels and other waste that are difficult to recycle.
3. Comprehensive treatment technology of urban domestic waste:
1. Introduction to the resource treatment technology of urban domestic waste
According to the analysis of domestic waste treatment methods, the correct Anxian's domestic waste treatment process will adopt a "rapid, harmless, full resource, industrialized, intelligent" waste treatment process.
The advantages of the treatment process are as follows:
1) It solves the problems of urban domestic waste sanitary landfill process that covers a large area, has short usage time, long occupation time, pollutes groundwater, pollutes soil, and pollutes the atmosphere;
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2) It solves the problem of expensive operation costs of pure waste incineration and pure incineration power generation processes, and the difficulty in treating the toxic gases produced by incineration;
3) It solves the problem of low-quality fertilizer in composting process that is difficult to recycle , the problem of flies and mosquitoes breeding in compost treatment plants, harming the health of surrounding people.
2. Process description of urban domestic waste sorting workshop:
Urban domestic waste is transported into the garbage sorting workshop through garbage transfer stations and garbage trucks. After weighing, the garbage trucks enter the closed The garbage sorting workshop unloads the garbage into a temporary garbage storage pit with a capacity of 1800m3, and sprays deodorant during unloading. The garbage in the temporary garbage storage pit is fed to the skirt feeder through the grab bucket of the bridge-type double-girder crane, and is evenly transported to the 120mm crusher through the belt conveyor and electromagnetic iron remover (the electromagnetic iron remover recovers some metal). It can crush all bulky garbage and bagged garbage in the garbage (particle size greater than 400mm, crushing rate 99%). After crushing, the 0~120mm granularity garbage enters the drum garbage sorting machine. The food organic waste and part of the sand and soil garbage (under the screen) separated by the drum garbage sorting machine are directly sent to the crusher for crushing after being removed by the electromagnetic iron remover. (The crushing particle size is controlled below 30mm). The crushed kitchen organic waste and some sandy soil waste enter the organic fertilizer workshop through a belt conveyor to produce organic fertilizer (75-90% of the organic matter in the waste can be separated). The light garbage (objects on the screen) sorted by the drum garbage sorting machine enters the positive pressure sorting machine for sorting. In the positive pressure sorting machine, the incoming garbage meets the flat airflow vertically and has different specific gravity and different landing points. Carry out sorting. The (heavy products) wood, rubber, textiles, etc. separated by the positive pressure sorter enter the electromagnetic iron remover to remove iron. The heavy products after iron removal are crushed by the crusher as combustibles and enter the gas production workshop for gas production. The light products (light products) sorted by the positive pressure sorter enter the photoelectric sorter for further sorting. The impurities (leaves, paper, etc.) sorted by the photoelectric sorter are mixed with heavy products and sent to the gas production workshop for gas production.
The waste plastics sorted by the photoelectric sorting machine are sent to the wood-plastic workshop through a belt conveyor, where they are cleaned, granulated and blended with wood powder to produce wood-plastic boards or wood-plastic profiles.
Part of the separated sand is mixed with combustibles and then enters the gas production workshop for gas production. The fired slag enters the building materials workshop to produce aerated concrete.
The crushed organic kitchen waste and part of the sandy soil waste enter the organic fertilizer workshop through a belt conveyor to produce organic fertilizer. In the organic fertilizer workshop, the organic matter is completely matured during the hydrolysis and thermal oxidation process, and is completely expanded into powder during blasting, while the volume of inorganic substances such as sand and glass slag does not change, so the materials after blasting are dried After machine drying and screening by a screening machine, it becomes organic fertilizer, that is: all organic waste becomes under-sieve matter, and all inorganic matter becomes over-sieve matter (sand and gravel, glass slag), and the mixed organic and inorganic matter is sorted through the sieve. come out. This technology is the current domestic and foreign garbage sorting technology that completely separates organic matter and inorganic matter, that is, "thermal separation" technology.
3. Treatment methods:
1) Easily degradable organic matter, sludge, and leachate - making organic fertilizer (organic fertilizer workshop).
2) Sand and gravel - making aerated concrete (building materials workshop). ?
3) Plastics - washed, crushed, granulated and combined with straw sawdust to produce wood-plastic products (wood-plastic workshop).
4) Non-recyclable combustible materials - anaerobic combustible gas production (pyrolysis gas production workshop).
5) Waste batteries and metal objects - recycling.
4. The main features of this comprehensive management of domestic waste:
The modern production line is designed according to the garden-style factory plan, with three-dimensional layout, centralized control, computer management, and visual monitoring. Materials are conveyed in a sealed manner, gases are completely purified and then discharged. Wastewater is not discharged outside, achieving clean production. Garbage comes in and products come out. All indicators meet relevant national standards.
1) Fast: products are produced within four hours, and garbage is processed on the same day, achieving daily output and daily cleaning.
2) Harmless: fully enclosed operation, so no odor escapes; no plastic burning, so no harmful waste gas is generated or less harmful waste gas is generated; organic matter is hydrolyzed and oxidized with high temperature and high pressure, so sterilization is complete ; Fast processing, little or no leachate produced.
3) No surplus: All garbage is recycled and processed thoroughly. ?
4) Strong adaptability: urban and rural domestic waste, market waste, construction waste, medical waste, livestock manure, diseased livestock carcasses, food industry waste, agricultural waste, traditional Chinese medicine industry waste , wastewater treatment plant sludge, landfill leachate.
5) Small footprint: one-quarter of the compost method and one-sixth of the landfill method, and the land used can be used permanently.
6) High degree of resource utilization and industrialization: Due to thorough sorting and classification, all recyclable materials are reused, while reducing the amount of garbage incinerated and the amount of harmful gases produced (especially reducing The amount of dioxin produced in the incinerator is reduced by 100% compared to the pure incineration process).
7) Advanced equipment: Most of the main equipment are patented equipment developed through years of on-site experience and sublimation. They have low failure rates and good use effects, and are particularly suitable for the treatment of urban domestic waste in China's national conditions.
8) Energy recycling and waste disposal with low cost. The economic benefits are good and the output is much greater than the input. ?
4. Effects:
Using comprehensive garbage treatment technology to build a garbage treatment plant has mature technology, reliable technology, significant economic benefits, small project investment, short construction period, and fast recovery time. , the main equipment is mainly domestic patented equipment, with reliable performance, economical and applicable. There is no secondary pollution and a high degree of resource utilization. The products produced by its comprehensive processing technology have broad market prospects due to factors such as price and quality. It has completely realized that "mixing is garbage, separation is resources"; "coming in is garbage, going out is garbage" products” and the concept of resource recycling. It will definitely make due contributions to improving the human living environment, building a new socialist countryside, building a resource-based and conservation-oriented society, and developing a circular economy.
Hope this helps.