, the sedimentation rate for particles with a diameter of 10 microns is 30 meters per hour or 250 kilometers per year. For particles less than 0.1 mm in diameter, the Brownian motion is dominant. above the precipitation at lower altitude The sedimentation rate of the particles is reduced. due to increased atmospheric density As a result, particles of a certain size lose their ability to fall. At this level, the equilibrium of the sludge particles is established.