Due to the complexity of the composition of urban waste, and by the level of economic development, able to structure, natural conditions and traditional habits and other factors, so the treatment of urban waste is generally different with the national conditions, often a country in the regions also use different treatment methods, it is difficult to have a unified model. But in the end, they all take harmlessness, resourcefulness and minimization as the treatment goal. There are landfill, incineration, composting, comprehensive utilization and other ways, a higher degree of mechanization, and the formation of systems and complete sets of equipment. Foreign treatment methods have the following trends: (1) industrialized countries due to energy, land resources are becoming increasingly tense, the proportion of incineration is gradually increasing; (2) landfill method as the final means of disposal of waste has been a large proportion; (3) most of the developing countries of the agricultural type of composting is the main; (4) a number of other new technologies, such as pyrolysis, reclamation, heaps of mountains landscaping and other technologies, is constantly making progress.
Incineration is a widely used municipal waste treatment technology, large-scale waste incineration treatment system equipped with thermal energy recovery and utilization devices, due to comply with the requirements of the recovery of energy, is gradually rising to the mainstream of incineration. The wide application of incineration technology, in addition to economically developed, strong investment power, high calorific value of garbage, mainly lies in the incineration process and equipment is mature and advanced. A variety of incineration devices and new incinerators toward high efficiency, energy saving, low cost, low pollution direction, the degree of automation is getting higher and higher. At present, China's municipal waste disposal technology response is: sanitary landfill and high-temperature composting technology, and advocate the development of incineration technology in cities with conditions, especially in economically developed coastal areas. In recent years, the cities began to carry out basic and applied research work on waste incineration treatment, the development of a series of reverse combustion, including NF series, RF series of pyrolysis, HL series of rotary small garbage combustion furnace and a number of hospital garbage special incinerator, and the construction of a number of small and medium-sized city simple incineration plant (station).
With the development of China's economy and the improvement of people's living standards, the combustible and flammable content of municipal waste increased significantly, the calorific value of a significant increase in the general after the classification, sorting and other pre-processing, the calorific value of garbage has been close to the calorific value of municipal waste in developed countries. Therefore, some cities in China, especially in economically developed coastal areas, etc. have the basis for the development of incineration technology.
Question 2: What are the main harmless waste treatment methods? The three main treatment methods sanitary landfill, composting, incineration
Overhead city waste disposal site of the waste disposal methods with the rest of the world, the main use of sanitary landfill, composting, incineration, etc., most of the city's garbage using the heap, simple landfill disposal, sanitary landfill, mechanical composting, incineration treatment is also part of the application.
Landfill: For a long time, most cities in China have used open piles, natural ditch filling and pit filling to deal with domestic waste, which can only achieve general anaerobic treatment. However, in recent years, the construction of landfills is becoming more and more perfect, a number of landfills with a high level of successive completion, such as Hangzhou, Guangzhou, Suzhou, Beijing, Chengdu, Baotou and our city and other cities according to the actual situation of the city to establish a more complete sanitary landfill. At the same time, the landfill produced methane gas recovery and utilization technology has also been developed. At present, the landfill method is still the city's most important urban landfill waste disposal method.
Composting: In recent years, the city's waste disposal compost development faster. From the 1980s onwards, the application of "secondary fermentation process", due to the adoption of the mandatory sealing, shortening the fermentation cycle, composting machinery is also becoming more and more perfect, the production tends to industrialization. From the national point of view, has been designed for China's own mechanized waste composting treatment production line, but many cities still have a considerable part of the simple waste composting plant.
Incineration: incineration technology for the waste harmless, reduction, resource treatment of the most effective way for the future development of waste disposal.
Question 3: What are the optimal treatment methods for household waste? At present, the country's soil resources are very tight, so although the landfill is a common method, but not a long-term solution, so the current main method is still incineration, but not the optimal method.
The best method is composting. This method is good, but there is no sales channel for the fertilizer obtained after composting, and people are not willing to buy it, so the optimal method does not mean that it can be promoted nationwide.
Basically, there are three main treatment methods
1. Landfill treatment
Landfill is an effective method of large amount of municipal waste elimination, and is the final treatment of all the residuals of the waste treatment process, and at present, our country generally adopts the direct landfill method.
The so-called direct landfill method is to fill the garbage into the pit has been prepared to cover the compaction, so that its biological, physical and chemical changes, decomposition of organic matter, to achieve the purpose of reducing and harmless.
Tianjin City, south of the Water Park with the garbage heap mountain, creating an artificial environment, turning harm into benefit, the project covers an area of nearly 800,000 square meters, to the garbage and engineering waste soil according to 1:1 with the soil source as a heap mountain, for the leachate and the methane produced by the fermentation and the stability of the hill, etc., have taken the necessary measures.
The United States Kansas City (Kansas City) is a small city, not much population, the city is surrounded by a vast countryside, away from the city of a hilly mountainous low-lying selected landfill, in order to prevent secondary pollution, to take the following measures:
(1) at the bottom and around the impermeable layer;
(2) layered laying, that is, a layer of stacked garbage, which is then covered with soil and compacted, and, according to the introduction, some of the garbage dumping layers are also installed with air conduction and conduit pipes and utilize the methane gas generated.
In Koto Ward, Tokyo, Japan, there is a densely wooded, flowery land that people call "Yumeshima," and Yumeshima is all reclaimed from garbage.
However, many cities in our country still have most of the garbage to take the open pile, without any protective measures. Every garbage dump has become a source of pollution, mosquitoes and flies, rats and mice, the stench of the sky, a large number of garbage sewage from the surface into the ground, the urban environment and groundwater sources cause serious pollution. Shenyang City has 35 landfills in the 10 drilling samples, analyzing the garbage fault samples and groundwater quality, the analysis results found that:
1, groundwater quality deterioration, serious pollution, water turbidity and odor, the water are detected anaerobic Escherichia coli;
2, the garbage fault samples are detected toxic and harmful substances. Every day in Shanghai, there are tons of garbage transported to the suburbs of the seaside piling, a mountain of garbage up to 20-30 meters high, causing serious pollution of the surrounding environment.
Landfill disposal is one of the most common methods of garbage disposal, which is characterized by low disposal costs and simple methods, but is prone to cause secondary pollution of groundwater resources. With the increase in the amount of urban waste, landfill sites close to the city are becoming less and less suitable for landfill sites, and the opening of remote landfill sites has greatly increased the cost of waste discharge, so that the high cost is not even affordable.
2. Incineration
Incineration is a method of placing garbage in a high-temperature furnace to fully oxidize the combustible components, and the heat generated is used to generate electricity and heat. The United States Westinghouse and O'Connor jointly developed a waste-to-energy system has been successful. The system's incinerator in the combustion of garbage can be up to 7% humidity into a dry solid for incineration, incineration efficiency of more than 95%, at the same time, the incinerator surface of the high temperature can be converted into steam heat, can be used for heating, air-conditioning equipment and steam turbine power generation and other aspects of the U.S. part of the incineration plant's main technical indicators are listed in Table 1.
China's Shijiazhuang City, the city of Shijiazhuang, constructed incineration station, the Shenyang Municipality Environmental Science Research Institute introduced the Japanese waste incineration device for hospitals and other units of special waste for harmless treatment, the incineration process produces residual ash of about 5% of the weight of biological waste before incineration, generally high-quality phosphorus fertilizer. In recent years, China's waste incineration to generate renewable energy technology is increasingly given attention.
The advantages of incineration treatment is a good reduction effect (incineration residue volume reduction of more than 90%, weight reduction of more than 80%), treatment thoroughly. However, according to U.S. reports incineration plants are extremely expensive to build and produce. In most cases, the value of the electricity generated by the equipment is much lower than the expected sales leaving the local *** with a huge economic loss. Incineration is highly toxic due to the presence of certain metals in the waste, creating secondary environmental hazards. Incineration requires that the calorific value of garbage is greater than 3.35MJ/kg, otherwise, must be added to the combustion agent, which will make the operating costs increase to the point that the average city can hardly afford.
3. Composting
The domestic garbage is piled up into a heap, insulated to 70 ℃ storage, fermentation, with the help of microbial decomposition of garbage in the ability to ...... >>
Question 4: What are the methods of municipal waste treatment? (1) Compression treatment. For some small density, large volume of urban garbage, after compression treatment can reduce the volume, easy to transport and landfill. Some garbage can become high-density inert materials and construction materials after compression treatment. (2) Landfill. Different landfill methods can be used to meet the requirements of operation and elimination by utilizing the basic conditions available in each place. Landfills can handle both mixed municipal waste and the leftovers from other waste treatment processes and waste that cannot be recycled. (3) Garbage incineration. Waste incineration produces thermal energy that can be used to produce steam or electricity, as well as for heating or production needs. It is calculated that for every 5 tons of waste, 1 ton of standard fuel can be saved. However, waste incineration plants must be equipped with smoke and dust elimination devices to reduce the amount of pollutants emitted into the atmosphere. (4) Composting. Composting is a biochemical process that utilizes microorganisms to break down the organic million of the waste, precipitating carbon dioxide, water, and heat, while generating humus.
Question 5: How many ways are there to dispose of garbage? Food waste: refers to people in the process of trading, storage, processing, consumption of a variety of food waste. This type of waste is highly corrosive, decomposes quickly, and emits a foul odor.
Ordinary garbage: including discarded paper products, waste plastics, rags and various textiles, waste rubber, broken leather products, waste wood and wood products, broken glass, waste metal products and dust. Ordinary garbage and food waste are the main objects that can be recycled in municipal waste.
Construction waste: including soil, stones, concrete blocks, broken bricks, waste wood, waste pipes and electrical waste. This kind of garbage is generally handled by the construction unit itself, but there is also a considerable amount of construction waste often into the city garbage.
Sweeping garbage: including the waste in the public **** dumpster, public **** place of sweeping material, road damage after the waste, etc..
Hazardous waste: including dry batteries, fluorescent tubes, thermometers and other kinds of chemical and biohazardous materials, flammable and explosive substances and waste containing radioactive substances. This type of waste generally cannot be mixed with ordinary garbage.
There are three main ways of harmless garbage disposal:
Landfill: Landfill garbage has less investment and large treatment capacity; the technical requirements are not high. But it has a large permanent footprint and a high potential for causing pollution. In the United States and other developed countries have appeared in the landfill decades after the events caused by pollution.
Composting: Composting is used to treat garbage, which can turn garbage into organic fertilizer. But this kind of garbage fertilizer has low fertilizer efficiency, limited sales, and little room for development.
Incineration: Incineration of garbage has the advantages of heat recovery and the most complete reduction of garbage (80% to 95% reduction in the volume of garbage after incineration), but this method is very expensive. The construction of an incinerator with a daily capacity of 1000 tons of garbage and ancillary heat recovery equipment will cost about 700-800 million RMB.
Question 6: How many ways to deal with garbage A basic status quo China's garbage disposal started late, the harmless treatment of garbage capacity is relatively low, there was a garbage surrounded by the city of the serious situation. In recent years, China's environmental sanitation industry has had a large development, so that the level of urban garbage disposal has increased, and the phenomenon of garbage surrounding the city has been eased. According to 1994 statistics, there were about 380,000 sanitation workers in cities throughout the country***, with about 34,400 various types of sanitation machinery, a garbage disposal rate of 35.8 per cent, and 609 harmless disposal sites, with the capacity for harmless disposal of garbage and the rate of disposal having grown very significantly in recent years. All major cities in China have set up scientific research institutions for environmental sanitation, and have carried out research on urban garbage disposal technology and equipment. During the "Eighth Five-Year Plan" period, the state allocated nearly ten million yuan and loaned tens of millions of yuan to carry out scientific research, development and demonstration projects on composting, landfilling, incineration and resource utilization of municipal waste. The application of garbage treatment technology is a systematic project, including garbage collection, transportation, transfer, treatment and resource utilization, etc. 1. Collection of garbage in cities and towns Most cities and towns in China now use mixed collection methods for garbage collection (except hospital garbage). The garbage operation methods and equipment used are mainly as follows: fixed garbage bins, garbage storage collection, movable garbage bins, garbage collection, garbage can collection, plastic bag collection. Sealed container collection and ground garbage station collection, etc., the vast majority of cities can do timely garbage collection, to maintain the environmental cleanliness of residential areas. 2. Urban garbage transportation from the overall view, China's urban garbage mechanized collection and transportation rate is low, sanitation workers labor intensity, manual operation, insufficient machinery, equipment performance is poor, the country's about 40% of the sanitation appliances, vehicles and so on need to be renewed, every year about 10 million tons of urban garbage and therefore can not be transported in a timely manner, and the garbage can not be transported in a timely manner. About 10 million tons of urban garbage can't be transported to the treatment site in time because of this.3. Urban garbage disposalCurrently, China adopts the same garbage disposal site and resource technology as the rest of the world, mainly using sanitary landfill, composting, incineration and other methods, in which most of the urban garbage adopts the stacking and simple landfill treatment, and sanitary landfill, mechanized composting, and incineration are also partially applied. China's municipal waste disposal methods mainly include waste-made building materials (bricks) and comprehensive utilization. (1) Application of landfill technology For a long time, most cities in China have used open piles, natural ditch filling and pit filling to treat waste. Only general anaerobic treatment can be achieved. However, in recent years, the construction of landfills has become more and more perfect, and a number of landfills with high level have been built one after another, such as Hangzhou, Guangzhou, Suzhou, Beijing, Chengdu, Baotou and other cities have set up more perfect sanitary landfills according to the actual situation of the city, and at the same time, the technology of recovering and utilizing the biogas produced by landfills has also been developed. At present, landfill is still the most important way of harmless treatment of urban landfill waste in China. (2) Application of composting technology In recent years, the development of waste composting in China has been relatively fast. From the 80's onwards, the application of "secondary fermentation process", due to the adoption of forced sealing, aerobic fermentation, shorten the fermentation cycle, composting machinery is becoming more and more perfect, the production tends to industrialization. At present, Wuxi, Changzhou, Tianjin, Shenyang, Beijing, Wuhan and other cities have designed their own mechanized garbage composting production line suitable for China, and many cities have a considerable part of the simple garbage composting plant. (3) The application of incineration technology, China's garbage incineration technology research started in the mid-1980s, incineration technology for the garbage harmless, reduction, resource treatment of the most effective way for the future development of garbage disposal, at present, China only has Shenzhen, Leshan, Xuzhou and a few other cities to set up a garbage incineration plant, incineration power generation demonstration test, the system is running well, but the scale is not large, the daily capacity is low. Large, low daily processing capacity. Beijing, Shenyang, Shanghai, Beihai, Guangzhou and other large and medium-sized cities are currently planning to build larger-scale waste incineration sites.
Question 7: What are the treatment methods for domestic waste? According to the different levels of development in different places, the way to deal with domestic waste is also different, so, for the time being, the way to deal with waste in the region is more scientific.