Refuse means and approaches

With the acceleration of economic development, urbanization and the improvement of people's living standards, waste emissions increased rapidly. Added garbage each year 10 billion t. Overrun with trash reality, vision of the world is no longer just how to control and destroy junk that old question, but take a more positive attitude and effective measures, scientific processing, garbage, rubbish as maintaining sustainable economic development "the second resource", to the waste to resources, to energy, to benefit.
At present, garbage stocks has reached 6 billion t of the calendar year, 500 million m2 of cultivated land occupied. National is 660, surrounded by the 200 cities in the city in the garbage. A case study of an urban population of 260 million, such as calculation 440 kg garbage produced per person per year, annual volume of waste was 114 million t.
In the 1950 of the 20th century until the middle of the 60 's, is the era of garbage pollution contradictions. After the middle of the 60 's, generally formed on a landfill, incineration, composting and other disposal methods. As in the United States, waste landfill disposal of 85%, only 10% treatment with incineration method. Japan land and much landfill handled only 26.9%, treatment with incineration method 61%. Switzerland is to incinerate method, 53%. In several countries in Western Europe dominated by landfill, and mostly a controlled landfill. Since in the 1970 of the 20th century, Japan, the United States, Britain, France and other countries, because of the resources and the effects of the energy crisis, was taken against waste "recycling" approach, garbage, feces disposal to keep the "resource" direction. Waste in particular, Japan has from the 25.3% of the city garbage sorting and recycling activities in 1976 recycle up to 39 million t, accounting for emissions of waste 49.5%. In recent years, some countries also developed the method of inorganic garbage mountains and trees, flowers and grass growing on the surface of the garbage mountain, developed parking, play a role to beautify the city.
1 the existing municipal solid waste treatment
The goal of solving the garbage problem is waste volume reduction, reduction, recycling, energy and sound processing. There are landfill, composting and incineration of three kinds of methods.
1.1 landfill
Landfill has a long history, is a commonly used treatment method. Because the method is simple, investment, can deal with all kinds of rubbish, so widely all over the world using this method. From uncontrolled landfill, the development of sanitary landfill, including the filter drain loop landfill, compressed landfill, broken, such as landfill.
Landfill method was used, first to prevent extrusion of liquid from the waste filter drain and groundwater pollution from stormwater runoff. General specifications the backfill to the lowest elevation to high ground-water level more than 3.3 m, and the lower part of impermeable rock or clay layers. Or else another impermeable clay, asphalt, plastic film. Secondly, the landfill should set the vent, released by the anaerobic microorganisms during decomposition of methane and other gases to escape in time to avoid explosion. After backfilling site, typically 20 years should not be built on it, avoiding the backfilling of uneven subsidence caused structural damage, but can be used as green space, farmland, pastures and other uses.
Landfill sites, try to use natural or artificial dig out depressions, and development resources of clay pits, quarries, abandoned mines and other waste. Landfill in the pit, is conducive to restoring landforms, maintain ecological balance, but if the large depressions, backfill such as bays and valleys, you will need to consider whether it will upset the balance.
1.2 composting
Composting is China, India and other countries to deal with garbage and feces of the oldest techniques, the production of agricultural fertilizer, but also countries all over the world are studying the use of a method. Compost is organic in the garbage, feces, in the presence of microorganisms, biochemical reactions, eventually forming a substance similar to humus soil, used as fertilizers or soil improvement.
Composting is the use of microbial decomposition of waste organic constituents of biochemical processes. In biochemical reactions, interactions between bacteria and organic matter, oxygen and release carbon dioxide, water and heat, and humus.
Key to composting, is to provide an environment of active growth of microorganisms, to speed up the process of decomposition by bacteria, to reach a stable. Composting is mainly affected by waste nutrients, control of factors such as temperature, humidity, pH.
According to the principles of composting, anaerobic digestion and aerobic decomposition of divided into two. Anaerobic decomposition should be strictly under anoxic conditions, anaerobic microbes grew more slowly, so not much use. Aerobic decomposition and temperature, can kill the eggs, bacteria, mainly aerobic decomposition.
Composting process is relatively simple, suitable for waste disposal of perishable high organic matter content, some components in the waste resource utilization, and deal with the same quality of investment than simple incineration of garbage is greatly reduced. Composting technology in Europe and the United States started earlier, has now reached industrial levels.

Burn refers to the combustible waste in the incinerator and oxygen for the combustion process. Essence of elements such as carbon, hydrogen, sulfur and oxygen chemical reaction. After the waste incineration, releases heat energy, both gas and solid residue. Heat energy recovery, flue gas cleaning and residue to digest, it is essential for the incineration process.
Incineration disposal technique is characterized by large capacity, good volume reduction, sound and complete, the heat from the incineration process used for power generation of waste energy can be achieved, so it is a waste treatment technology widely used in developed countries of the world.
By burning combustible solid waste oxidation and decomposition, removing toxic byproducts, energy recovery and access purposes. Almost all organic waste can be treated by incineration. For inorganic-organic hybrid solid waste, organic compounds are toxic and harmful substances, incineration is also best. Applies to fuel more of burning garbage. Incineration method is used, care must be taken not to cause secondary pollution of the air. Japan and Europe, Switzerland, and Sweden and other countries in General based on incineration, thermophilic and mesophilic decomposition is also developed, basic garbage in 1650 ℃ high temperature or combustion, and recycle the energy released as an energy source.
Incineration is a waste treatment technology for destruction of waste heat. However, prices were only for those who can not be recycled, only recovery of thermal energy from rubbish, waste incineration is scientific and rational.
2 limitations of existing municipal solid waste treatment methods
2.1 limitations of landfill
Bury the landfill was available, landfill site selection more difficult transport, landfill, and management costs are also rising. Landfill covers an area of large and serious secondary pollution, such as refuse leachate can contaminate groundwater and soil, dump the stench of severely affected air quality around the site, in addition, the waste is fermented to produce methane gas fire and explosion hazards, emissions into the atmosphere and produce the greenhouse effect. And limited landfill capacity, service upon the expiration of the investment to build a new landfill, further use of land resources. ┪ Crook  n   compromise it's offering the ┦? 2000 t/d sanitary landfill of waste treatment, construction investment alone up to 720 million Yuan (not including land costs), and the life of the landfill only 12 a. Based on the above reasons, from abroad since the 80 's, decreasing trend in sanitary landfill facilities, other treatment methods, used to process cannot use the substance.
2.2 limitations of the composting
Compost processing cannot processing not rot of organic and inorganic, garbage in the of stones, and metal, and glass, and plastic, waste cannot was microbial decomposition, these waste must points picked up out, separately processing, so reduction capacity, and reduction volume and the harmless of degree low; compost cycle long, accounted for to area big, health conditions poor; compost processing Hou produced of fertilizer effect low, and cost high, and fertilizer than sales difficult, economic poor. The introduction of foreign technology investment is huge, not suited to China's national conditions. In developed countries due to solid waste for perishable organic content is much lower than the country's average, compost can only handle around 15% waste composition, which to some extent hindered the promotion of composting. Composting of rubbish must be fresh perishable organic classification after the first fermentation, can effectively prevent infiltration of heavy metals, so as to ensure products reach the national standard of organic manure, truly harmless and resourceful.

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