Source-sorted waste sorting plants
Some plants are designed exclusively to handle, clean and dry paper from private households and paper and cardboard collected from offices. At such plants the material is received in a tipping hall and a front end loader is used to move the material onto a belt conveyor leading to the processing area. Manual sorting at the belt conveyer may either be negative, i.e. unwanted materials such as plastic bags can be removed from the main stream, or positive, i.e. the recyclable paper and cardboard materials can be diverted to give different quality fractions. The sorted fractions are transported to balers and the bales are shipped off to paper mills.
Compost and biogas producing plants
Several different systems for low and high technology composting exist. The biodegradable materials are in general shredded before composting, and when the compost process is finished, the compost is sieved to remove large items including materials which are not biodegradable.
In the simple low technology composting plants, the piles are established outdoors with no equipment for aeration. After a period of several months to years during which the piles are agitated mechanically, the compost is sieved and subjected to final composting. Due to the low content of structural materials in the biodegradable fraction of domestic waste, it is difficult to maintain an efficient composting process in this fraction. Therefore, the biodegradable fraction of domestic waste is often mixed with garden waste or with other biodegradable fractions such as sewage sludge and slurry from livestock buildings.