The circular economy is an economy, firstly, considering the natural resources as finite and the non-existence of waste, secondly, assimilating the industrial system as a natural system and, finally, emphasizing the paradigm of regeneration. Nevertheless, this paradigm is not clearly defined and this paper aims to found it by proposing solutions to its implementation in the industrial world. The proposal is based on a comparison between the natural system and the industrial system by using the trophic organization model and their elements. Then, the maintenance process is seen as a key element of regeneration. Finally, the notion of nutrient is studied and taken into account in an industrial process.