Freeing sludge of its mother liquor by washing it with water. The elutriation process is responsible for severing heavier particles from lighter ones due to the utilization of upwardly directed streams of liquid or gas. For this reason, this method is mainly prioritized with particles of certain sizes. Particles that are lighter or lesser in size are the ones that rise up to the top as a result of their sheer velocity, which are lower than the velocity of accompanying fluids.