 In this module, we will talk about another type of impellers that is axial flow impellers and their role in agitation of a fermentation medium. So, as concern the axial flow mixing that is considerably more energy efficient than the radial flow mixing. So, the axial flow impellers are mostly designed to decrease the energy consumption and then that is only need when there is less shear effect is needed because very when there is a sensitive conditions not shear effect is required then we mostly use the axial flow impellers. So, they are more effective at lifting the solids from the base of the tank. Sometimes when there is a partially soluble content in the medium that mostly tend to precipitate or tend to settle down at the bottom. So, the radial flow impellers cannot uplift those material. So, axial impellers help or facilitate to disperse those content of the medium as well as the biomass produced in result of the fermentation they tend to settle down in the bottom of the fermenter. So, the axial flow impellers as compared to the radial flow impellers have low shear properties. The angled pitch because they have angled pitch agitators coupled with the thin trailing edge of the impeller blades that reduce the formation of edge in wake of the moving blades. So, that is why the shape of the axial impellers that basically design in such a way that have a less resistance when they move into the fermentation medium. So, that is why they need a less energy and then they have a less shear effect during their movement they are revolving when they revolve in the fermentation medium. So, axial flow impellers along with their blades are pitched at the angle and thus direct the liquid flow toward the base of the fermenter. So, there are different examples and there are different further shapes and size of axial flow impellers. So, you can see here the two different kind of axial flow impellers and these axial flow impellers are mostly used in a daily life when we have a experience of a boating and then that use as a propellers just to push the water behind and then the boat move forward and then in an ordinary life we see that the wing of a sealing fan that is also designed in such a way that look like the axial flow impellers. As we see that when the sealing fan work and then that cut the air from outside but from the upper side to the lower side and then push the air toward the floor of the house or floor of the room the same way when these axial flow impellers move they push the fermentation media from the top to the bottom of that and then they press and then what happen then those either insoluble particles or the biomass we tend to settle down at the bottom they move toward the periphery and then they go and then there is a gradually mixing of the different particles exist in that fermentation medium. So, you can see here as we have told in our previous discussion that these are the actually we can see here that the different edges and their bend that basically tend that facilitate the axial flow of the medium that is why we will in later modules we will talk about in detail that how the axial impellers work.