Domestic waste can generally be divided into four major categories: recyclable waste, kitchen waste, hazardous waste and other waste. Currently commonly used garbage disposal methods include comprehensive utilization, sanitary landfill, incineration and composting.
Recyclable waste includes paper, metal, plastic, glass, 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 waste paper recycled Steel can produce 0.9 tons of steel, which saves 47% of the cost compared with ore smelting, reduces air pollution by 75%, and reduces water pollution and solid waste by 97%.
Kitchen waste includes food waste such as leftovers, bones, roots and leaves, which can be composted on-site through biotechnology and can produce 0.3 tons of organic fertilizer per ton.
Hazardous waste includes waste batteries, waste fluorescent tubes, waste mercury thermometers, expired medicines, etc. These wastes require special safe handling.
Other waste includes bricks, ceramics, slag, toilet paper and other waste that are difficult to recycle in addition to the above categories of waste. Sanitary landfill can effectively reduce the impact on groundwater, surface water, soil and Air pollution.
Some experts say that garbage is the only growing resource on the planet, and it is also a resource that has been misplaced. We also often say that we should "turn waste into treasure". However, without various application technologies for waste resource utilization, waste will still be waste and will never automatically become "treasure". Since the 1980s, my country's waste energy production and recycling and reuse technologies have developed rapidly. 1 ton of waste glass can be processed through mechanized processes to produce 20,000 beer bottles or window glass equivalent to the area of ????a basketball court; after waste plastics are recycled, they can be turned into crude oil, from which diesel and gasoline can be extracted; approximately Kitchen waste and peel waste, which account for 65%-70% of the total urban domestic waste, can be "eaten in" using biochemical technology and specialized machines. Using the principle of microbial fermentation, the waste can be turned into granules on the spot within 24 hours. Or powdery fertilizer or feed, for use in public green spaces or for citizens to grow flowers at home.
After the usable part of the garbage becomes recycled resources, how is the remaining waste finally disposed of? How to prevent secondary pollution and let garbage end its life and enter the "grave" quietly and harmlessly? These questions will be gradually answered with the development of science and technology and the adoption of advanced technology.
Incineration is a high-temperature treatment process for municipal waste. In the incinerator furnace at 850-1000 degrees Celsius, the chemically active components in the waste are fully oxidized and the remaining inorganic components become molten waste. The slag is discharged, in the process the volume of the garbage is reduced and its perishable nature is fully changed. Generally speaking, when garbage is incinerated, it will undergo several steps such as dehydration, degassing, ignition, combustion, and flameout.
The method of using microorganisms to degrade municipal organic solid waste is called biological treatment, also generally called composting. According to the different oxygen requirements of the microorganisms that function during the treatment process, organic waste treatment can be divided into two types: aerobic composting (high temperature composting) and anaerobic composting.
Because municipal solid waste contains a certain amount of organic matter, unstable organic matter can be converted into more stable humus through biochemical changes through the action of a wide variety of microorganisms widely distributed in nature. Composting from municipal waste is actually an ancient and practical method, and it is also the traditional way of processing and utilizing municipal waste in my country and some developing countries.
Landfill is a final treatment technology for municipal solid waste developed from traditional stacking and landfill treatment. Its essence is to spread the waste into a thin layer of a certain thickness, compact it, and cover it. soil. After municipal solid waste is landfilled, the organic and easily biodegradable substances in it produce a large amount of methane gas under anaerobic conditions. After being collected, it can be used for power generation or heating, so that the waste can be utilized as a resource while avoiding excessive accumulation. potential harm caused.
The fifth team introduced: the prospects of municipal solid waste treatment.
my country has paid more and more attention to municipal solid waste. From November 12 to 13, 1999, the Regional Ecological Economics Professional Committee of the China Ecological Economics Society and the China Packaging Association jointly organized the first "China Municipal Domestic Waste Situation and Countermeasures Academic Seminar" in Beijing.
The problem of municipal solid waste has always been an unavoidable problem for people and a headache for policy departments. So, is there a way to reduce government investment and turn waste into treasure? The industrialization of waste disposal may be a good way to solve this problem. The garbage industry is a very profitable industry abroad. Guangzhou City in my country has begun to promote the industrialization of waste treatment as early as 1996. It is currently developing rapidly and is well ahead of most cities in the country. It is expected that by 2010, the collection, transportation and treatment of urban domestic waste in Guangzhou will be fully market-oriented. Currently, Guangzhou is planning to build a domestic waste recycling and processing center that will integrate waste classification collection, scientific decomposition and recycling plants. The rise of the garbage industry tells people: garbage is not worthless, but resources, wealth, and treasures.
If we want to control the amount of urban domestic waste, we must first change some of people's old living habits. For example, a large part of the increase in municipal solid waste in recent years comes from the increase in discarded packaging. In this regard, many foreign countries have formulated special legal provisions to impose restrictions and put forward the concept of "zero packaging". "Zero packaging" does not mean eliminating packaging, but simplifying and reducing packaging while using available and biodegradable packaging materials. Relevant experts pointed out that based on some advanced foreign management experience and my country's current situation, it is imperative to formulate packaging management measures. For example, tax policies should be adjusted to promote simple packaging and restrict excessive packaging. In addition, through "product liability" legislation and other measures, companies should strengthen their environmental awareness and reduce the amount of waste generated from the source. The provisions on "product liability" in Germany's "Circular Economy and Waste Management Act" are a good reference.