3. Operating principles

Source separation aims to manage the different fractions that make up domestic wastewater. To achieve this, a succession of stages is used to develop a functional process for managing the materials with a view to recovery. These five interdependent stages (see figure 2 ) define the outline of a source separation process. Within this framework, a choice made by an operator (prime contractor, owner, operator, etc.) for one stage generates changes in the upstream and downstream stages of the chain. The transport stage is not necessarily in third place. It can also be positioned after treatment, or even in both places at the same time. We therefore need to clarify the composition and articulation of these stages.