Analysis on the present situation of solid waste treatment technology
With the rapid development of the city, solid waste has become an important pollutant that destroys the urban landscape and pollutes the environment. It occupies a lot of land, and its harmful components enter the environment through water, atmosphere and soil, causing potential and long-term harm to human beings. Therefore, it is of great significance for the sustainable development of the city to do a good job in the treatment of urban solid waste.
Solid waste; Handling; sustainable development
Environment is the basic condition for human survival and development. Facing the reform of urban residents, the expansion of urban scale, the increase of population and the rapid development of industry, the discharge of solid waste is increasing day by day. Therefore, the treatment of municipal solid waste has attracted public attention and become one of the hot spots of many resources and environmental problems.
I. Sources and Classification of Municipal Solid Waste
Solid waste refers to solid and semi-solid waste that pollutes the environment in production, construction, daily life and other activities. Starting from its sources and management needs, China can be divided into the following three categories:
1. Industrial solid waste
Industrial solid waste refers to the solid waste produced in industrial and transportation production activities, including metallurgical solid waste (such as blast furnace slag, steel slag, red mud, non-ferrous metal slag, etc.). ), fuel ash (such as fly ash, cinder, flue ash, shale ash, etc. ), chemical solid waste (such as sulfuric acid residue, waste gypsum, salt mud waste rock, chemical mine tailings, etc. ), as well as solid waste from the petroleum industry (such as
2. Municipal solid waste
Municipal solid waste (MSW) refers to the solid waste generated in the daily life of the city and the solid waste identified as MSW by laws and administrative regulations. According to the source, it can be divided into: domestic garbage, food garbage, scattered garbage, market garbage, street cleaning, hospital garbage, construction garbage and feces. The composition of municipal solid waste is mainly influenced by scale, nature, geographical conditions, residents' living habits, living standards and civil fuel structure. In developed countries, most urban residents' excreta are fed into sewage treatment plants through underground waterways, while in China, the urban groundwater system is not perfect and there are few sewage treatment facilities, so excreta needs to be collected and removed, which is an important part of urban solid waste. The reform of urban residents has promoted the production of solid waste in the surrounding areas of the city to account for a large proportion, especially the rapid increase of construction waste, and the treatment of urban solid waste is imminent.
3. Hazardous waste
Hazardous solid waste refers to wastes that are flammable, explosive, chemically reactive, corrosive, acute toxic, chronic toxic, ecological toxic or infectious, and are harmful to the living environment of human beings, such as smelting slag, chemical waste and radioactive waste generated from the production and processing of mother liquor and nuclear fuel, which need to be managed separately.
Second, the way and harm of solid waste pollution
Solid waste, especially hazardous solid waste, will endanger human health in different ways if it is not handled properly. The chemical components contained in industrial and mining solid waste will form chemical pollution; Feces and domestic garbage are evil breeding grounds of various pathogenic microorganisms, which can form pathogen pollution.
Solid waste has the characteristics of many pollution sources, complex pollution causes, wide harm range and difficult management. It is harmful to human environment in many aspects, mainly including a lot of land occupation and soil pollution; Blocking waterways and polluting water bodies; Produce harmful gases and pollute the atmosphere; Obstruct the landscape, affect the city appearance and environmental sanitation, spread diseases and endanger human health.
Three. Characteristics of Municipal Solid Waste in China
3. 1 Ways and classification of solid waste generation
The way in which social materials flow and solid wastes are produced keeps the materials of all activities in human society in a dynamic state of balance and follows the law of conservation of mass. Compared with the external environment, all human activities are only the development and utilization of natural resources, and eventually resources will return to the environment in the form of waste. In modern society, from the development of raw materials in the environment to the utilization of products, all kinds of wastes will be produced in every link of human activities. Urban solid waste refers to the solid waste produced by urban residents in their daily life or in the activities of providing services for urban daily life. The main components are kitchen waste, waste paper, waste plastic, waste fabric, waste metal, waste glass, ceramic fragments, brick and tile residue and feces. And waste household appliances, waste electrical appliances, garden garbage, etc.
The classification of solid waste depends on the way and nature of its production. Because there are many kinds of municipal solid waste, the classification methods are different. Different classification determines the methods and means of solid waste treatment. According to the source of urban solid waste, it can be divided into industrial solid waste, domestic waste and other solid waste; According to the pollution characteristics, solid waste can be divided into general solid waste, hazardous waste and radioactive solid waste; According to chemical properties, it is divided into organic solid waste and inorganic solid waste.
3.2 Pollution and harm of urban solid waste
At present, all large, medium and small cities at home and abroad are facing the threat of solid waste. Take China as an example. At present, the annual industrial solid waste is more than 654.38+0 billion tons, and the cumulative amount is more than 654.38+0 billion tons. 600 million tons of domestic waste every year. Environmental pollution mainly includes water pollution, air pollution and soil pollution.
Water pollution: If the solid waste without harmless treatment is piled up at will, it will cause urban groundwater pollution and reduce the water quality and use value. Its pollutants mainly include organic pollutants, heavy metals and other toxic substances. Air pollution: Fine particles and dust in piled solid waste will fly with the wind, thus polluting the atmospheric environment. Soil pollution: Solid wastes are randomly piled up in the open air, occupying a lot of land and destroying landforms and vegetation. Toxic substances seeping from solid waste after being soaked in rain and snow will kill microorganisms in soil, destroy its ecological balance and change soil structure and soil quality. Toxic substances can also enter the human body through the enrichment of crops, and ultimately endanger human health through the food chain.
Four. Analysis on the present situation, advantages and disadvantages of municipal solid waste treatment
Solid waste treatment refers to the process of making solid waste suitable for transportation, storage, resource utilization and final disposal through physical, chemical and biological methods. Physical treatment of solid waste includes crushing, sorting, precipitation, filtration, centrifugal separation and other treatment methods; Chemical treatment includes pyrolysis, curing and other treatment methods; Biological treatment includes anaerobic fermentation and composting. In view of the serious pollution of solid waste to the environment, at present, China usually adopts the following three treatment methods for municipal solid waste:
4. 1 landfill
Landfill technology is to use natural terrain or artificial structure to form a certain space, and to landfill, compact and cover solid waste to achieve the purpose of storage. The essence of this method is to spread solid waste into a thin layer with a certain thickness, and then compact and cover the soil layer. Landfill is not a simple landfill and burial, but an engineering system with scientific site selection, necessary site protection and strict management system. Landfill has the advantages of mature technology, low investment, large treatment capacity, low operating cost, convenient management and transportation, and the biogas produced by landfill can be used as energy, which has been widely used in urban garbage treatment in China. Landfill is the final destination or final disposal place of solid waste and an important means to protect the environment. For hazardous waste, it may need to be solidified and stabilized, and for landfill, it needs strict anti-seepage structure.
4.2 Incineration
Incineration is a high-temperature heat treatment technology, that is, a certain amount of excess air reacts with the treated organic waste in the incinerator, and the toxic and harmful substances in the waste are destroyed by oxidative pyrolysis at high temperature. The workflow of solid waste incineration treatment is shown in. Using incineration technology to treat solid waste not only has good reduction effect, but also has large capacity and is completely harmless. The waste residue after incineration is non-toxic and harmless, which is an excellent raw material for building materials, and the heat energy can be recycled, which is another way of resource utilization. The biggest impact of incineration technology on the environment is the pollution caused by tail gas. In order to prevent secondary pollution, improving working condition control and tail gas purification is the key to reduce pollution control when this method is used to treat municipal solid waste.
To sum up, solid waste is a misplaced resource. Making full use of solid waste can not only relieve environmental pressure, but also save resources. The main way to control the environmental pollution and harm to human health by municipal solid waste is to recycle, harmless and reduce the solid waste. Landfill, incineration and composting can realize or partially realize the harmless disposal of solid waste, so that solid waste or its harmful components will not harm the environment or be transformed into environmentally harmless substances. However, when dealing with municipal solid waste, we should also pay attention to the recovery of resources. It has become a new trend to recycle solid waste, energy and resources and realize the recycling of waste.
References:
[1] Guo Donghua. Liu xianwen Study on reinjection treatment of solid waste after water quality improvement in Nanlin Oilfield [J]. Pollution prevention technology. 03, 2004.
[2] Yu Yongqing. Present situation and measures of solid waste resource utilization [J]. Heilongjiang Science and Technology Information .2009, 17.
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