There are strong and weak uses or senses of the term 'circular economy'.
The strong sense, which is more often vaguely held or entertained than spelled out, supposes that an economy can proceed for an indefinite period without external input, simply by reprocessing the outputs of one stage as the inputs of a succeeding stage. There are no losses, and no wastes are discarded. We have never observed such an economy, and attempts to devise a system on these lines will fail because such a system is in effect a perpetual motion machine, which the laws of thermodynamics tells us is impossible.
The weak sense, which encompasses almost all practical suggestions for a circular economy, suggests that the economy achieves as much reprocessing of outputs as is possible without increasing the energy inputs to achieve reprocessing. In other words we recycle as much as is economic (that many recyclers are not aware of this limitation is true, but hardly worth discussion). This weak sense is only interesting insofar as it it represents a novel state of affairs. Since the proposition in fact describes the normal economy,it is empty rhetoric insofar as it claims novelty.
Thus the strong sense of the circular economy is false, and the weak sense is banal.