Abstract: The invention relates to a process and an apparatus for the processing or treatment of fluids containing suspended particles and more particularly usable for the processing or treatment of gases and liquids contaminated by radioactive particles.The fluid to be treated undergoes a treatment cycle in the circuit. This cycle comprises a filtering stage performed in the filtering apparatus in order to extract part of the fluid in the purified state and a separating stage performed in the separating device for extracting part of the particles present in suspended form in the fluid. It is possible to commence the processing cycle either by the filtering stage, or by the separating stage. The particle-depleted fluid from the separating stage or the particle-enriched fluid from the filtering stage undergoes a further processing cycle after adding thereto fluid to be treated by means of the pipe.