China will subdivide municipal garbage into four groups: material waste group (including glass, magnetic or non-magnetic metals, waste paper, rubber and plastics), organic waste group (kitchen garbage, biological waste), inorganic waste group (furnace ash slag, bricks and mortar, ceramics, etc.), and poisonous and hazardous waste group (used batteries, used fluorescent tubes, pesticide containers, expired medicines, medical wastes as well as used TV sets, telephones, computers and other waste electrical appliances of electronic waste). China's urban garbage disposal started very late, with garbage disposal only beginning in the 1980s. Before that, garbage was piled up in the open. According to the information from the Municipal Waste Disposal Committee of China Environmental Protection Industry Association (CEPIA), China's municipal waste disposal rate was less than 2% before 1990. It was only after entering the 1990s that China's urban garbage disposal improved continuously. in 1999, China's municipal cities were 668, *** there were 696 garbage disposal plants (yards), including less than 200 non-hazardous treatment plants, with a garbage disposal rate of 63.4%, and a non-hazardous treatment rate of 20.3% only.
There are more than 700 harmless treatment plants for domestic waste alone in Chinese cities, and the rate of harmless treatment of domestic waste in Chinese cities is 52%. Waste disposal in Chinese cities first goes through collection. China's urban garbage collection is basically a mixed collection, although the Chinese government advocated separate collection in 2002, but the separate collection of garbage still only accounts for 16%. There are three main types of mixed collection, one of which is to place collection containers in fixed locations, such as residential neighborhoods, on both sides of the street, and in other public **** places. Specialized sanitation staff are responsible for collecting garbage from these containers every day. Second, there are fixed garbage collection stations in residential neighborhoods where residents can throw their household garbage to the garbage station every day. Thirdly, there are garbage lanes. In high-rise residential buildings in China, the garbage lanes are already designed when the building is constructed, from the first floor all the way to the top floor, so that residents can throw their garbage into the garbage lanes and the sanitation staff will take it away from the bottom floor. Collecting residents' garbage through garbage tunnels used to be the most common way of collecting garbage in residential areas. However, after the SARS outbreak in 2003, it was banned in many cities because it was conducive to the spread of bacteria. Cities such as Beijing, Guangzhou, and Shanghai have mandated that new residential buildings do not have garbage lanes, and some cities have also closed garbage lanes in already-built residential buildings and stopped using them.
The collected garbage is transported to the garbage transfer station by special garbage trucks. The garbage trucks are completely sealed. After the garbage is transported to the transfer station it undergoes the first step of processing. It is first classified by a sorting machine into organic and inorganic materials, as well as utilizable and non-utilizable. Bulky waste is also compressed. After that, the waste is sorted and transported away.
From the transfer station, some of the garbage is transported to sanitary landfills, where the garbage is filled into pits that have been prepared, covered and compacted, so that it undergoes biological, physical, and chemical changes to decompose organic matter, and to achieve the purpose of reduction and harmlessness. Special pipes and impermeable layers are laid in these pits to collect the gas and leachate produced by the fermentation of the waste. The gas is burned, part of the leachate is purified and processed into water, which is used to clean the garbage vehicles as well as the dust on the ground, and part of the leachate is filtered to meet the national level standards before being discharged, without causing pollution to the environment. Some of the leachate is transported to a composting plant, where it is composted and turned into hygienic, odorless humus, which is used as fertilizer for plants. Still others are sent to incinerators for burning to fully oxidize the combustible components of the waste, and the heat generated is used to generate electricity and heating. Today, China has 140 waste-to-energy plants built, under construction and in the process of approval. One ton of garbage can generate 300 degrees of electricity, and the waste heat can also be used for heating. The Tianjin Shuanggang garbage power plant, which handles 1,200 tons of garbage per day, generates 120 million degrees of electricity annually, which is enough to power 50,000 households for a year, and is equivalent to saving 48,000 tons of standard coal. For recyclable garbage, it will be recycled and reused. In the process of dealing with garbage, China has formulated a number of relevant standards, such as the standards for controlling agricultural use of urban garbage, the standards for harmless sanitation of feces, and the standards for emission of incineration exhaust gas.
Among the waste treatment methods, incineration is slower to develop in China, mainly because of the lack of funds. The initial investment in incineration is large, and the construction of an incinerator with a daily capacity of 1,000 tons of garbage and ancillary heat recovery equipment requires about 700-800 million yuan. Moreover, because incineration produces dioxin gases when treating waste, many cities do not use incineration much except for the need to treat medical waste. Many cities are more likely to use sanitary landfills, a method that environmental officials say is better suited to China's national conditions.
Chinese Environmental Protection Industry Association Urban Waste Disposal Committee data show that 70% of China's urban waste disposal is landfilled, 20% is composted, 5% is incinerated, and the rest (including open piles and recycling) accounts for 5%.