Biological treatment is widely accepted as a treatment method for biological waste. Composting is a robust practice and state of the art. The anaerobic digestion offers the possibility of producing energy from waste. That means a significant reduction of CO₂ emission because of savings in fossil fuels. The comparison between composting and digestion of biological waste is very useful for decision guidance for treating biological waste. Many aspects have influence on a recommended action for a treatment decision. The following the focus is put on a comparison referring to degradation rates, because degradation and therewith stabilisation of the waste is the main objective of biological treatment.