Choosing the right technology depends on the way of collection and on the waste quality.
When a selective collection can be organised in order to obtain a source separated organic material almost free of refuses, a very high quality stabilised soil conditioner is available after treatment.
In the case of a bulk waste collection, an automatic sorting unit, upstream from the treatment, permits the separation of the organic material from the other waste.
Downstream from selective collection or downstream from bulk collection followed by mechanical sorting, the biological treatment of the organic material can be made by anaerobic digestion (oxygen-free fermentation) also called methanisation, or by aerobic composting or else by a combination of anaerobic digestion and aerobic composting.
The anaerobic digestion of the organic material is usually followed by a short aerobic phase (about two weeks) which completes the stabilisation of the digested matter. After this phase, the compost is fully stabilised (degree 5 of the German norm LAGA M10) and can be stored and
The possible excess process water, related to the incoming waste moisture, can be discharged into the sewage network, after an additional purification step if necessary, depending on local regulations.