Stale garbage is the product of natural degradation of domestic garbage after years of landfill or stacking. Stale garbage is also called landfill garbage, pile garbage, mineralized garbage, and stock garbage. The composition of domestic garbage will change greatly after landfill treatment. Most of the organic matter such as vegetable market garbage, which accounts for a large proportion, will be decomposed over time; the proportion of bamboo and wood, which are more difficult to degrade, is relatively small; while plastics, leather, fabrics, metals and other materials will not change or reduce in volume with the landfill time.

Three major advantages of mechanized sorting and treatment of stale garbage:

(1) Reducing the amount of garbage can obtain land resources, allowing the landfill to be reused and increasing its service life. Through the comprehensive garbage management process, the garbage volume is reduced, and the landfill site is restored, so that the original land can be redeveloped. In the situation of increasingly tight land resources, the treatment of stale garbage in the original closed landfill has great market potential.

(2) Waste resource utilization. There are a large number of high-water content kitchen wastes in domestic waste, while the stale wastes after years of degradation have a lower water content, higher calorific value and higher value. Most of the stale waste can be used for resource utilization after sorting. Waste plastics can be directly packaged and sold or further processed; metal ferromagnetic materials can be recycled and sold directly; the rest is mainly textile combustibles, etc., which can be used for incineration power plants; humus soil can be used for landscaping; bricks and stones and other inorganic materials can be harmlessly backfilled.

(3) Harmless waste can eliminate the pollution of landfills to the surrounding environment and groundwater, especially the large number of original informal landfills. Due to the lack of effective protection measures during the operation period, the water, air and odor pollution generated not only have a serious impact on the lives of surrounding residents, but also cause harm to groundwater. Zhengzhou Zhongcheng garbage sorting equipment combines the characteristics of stale garbage to develop sorting equipment that is more efficient and environmentally friendly. Through the sorting and treatment of stale garbage, the original pollution sources can be effectively eliminated, the ecological environment can be improved, and environmental and social benefits can be achieved.