Safe landfill

　　Urban landfill is the most basic disposal method for urban garbage. Although municipal waste can be disposed of by incineration, composting or sorting recovery, some of the residues that are difficult to handle still need to be disposed of as final landfill. The use of potholes to land municipal waste can not only dispose of waste, but also cover the land and protect the environment. The main methods of urban landfill are:
　　(1) Sanitary landfill. Pour a layer of municipal waste (60 cm thick), compact it, cover 15 cm thick soil, sand or fly ash, and repeat, and finally cover 90-120 cm of topsoil.
　　(2) Compress landfill. After the garbage is compressed and backfilled, it can be fireproof, prevent mosquitoes and slow down.
　　(3) Broken landfill. It can be fireproof and is beneficial to the breeding of aerobic bacteria. The lowest part of the landfill site for urban waste should be more than 3 meters above the groundwater level. The landfill should adopt anti-seepage and exhaust measures. After the landfill is closed, it can be used as a greening place. Permanent buildings cannot be built on it.
　　Due to the advantages of mature technology and low processing cost, sanitary landfill is the main method for centralized disposal of municipal waste in China.
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