Mud cleaner is a combination of desanders and/or desilters mounted over a shaker with a fine mesh screen.
The drilling mud is fed to the inlet of the desander cone, the coarse particle and fine particles are separated by different centrifugal force, the particles larger than 70 microns are separated and fine particles remained in the drilling fluids and dropped into the mud tank.
The feeding pump of desilter cone fed the mud to desilter cone, then particles larger than 20 microns are separated. 
The coarse solids are dropped on the shaker screens for dry and some clean drilling fluids are recycled and solids are separated, maybe collected by screw conveyor to the drilling waste management system.