 In this module, we will talk about the oxygen delivery system in a fermentation vessel. So along with the agitation system, the oxygen delivery system or aeration system is very critical. So as concerned, the oxygen delivery system that is consist of a compressor that compress the air that can be an ordinary air having we know that what is the chemical composition of a common air having 21% oxygen. So we can use a pure cylinder of different gases as the requirement of the fermentation process. And then the second part is inlet air sterilization system very critical because fermentation process need a septic operation. So that is only one source of contamination that is the air. So if we assure the sterilization of that air supply to the fermentation medium because they have to the direct contact with the fermentation vessel. So the air sterilization system and the third is air sparger. Air sparger basically these are the select or the pores of that pipe which fit inside the fermentation vessel that basically give a proper size and the shape to the air bubbles inside the fermenter. And the fourth one that is the exit point just to maintain the containment regulations. You can see in this diagram that a compressor and this is a sterilization system and this one is a sparger system and then there is the exit air system and that is fitted with the sterilization system. So what is the role of the compressor? Compressor force the air into the reactor because air has to pass through the sterilization system and the sterilization system mostly consist upon the filter that we will talk about later on that has a very tiny pores and air can only pass through those filter in a force condition in a high pressure. So that is why air compressors used for the large scale bioreactors typically produce the air at 250 kilo Pascal. So the air should be dry and oil free. Why? Because when different compressors that when they move their piston move that having the lubrication. So that when that compress the air then there is a oil particles can come into the fermenter vessels along with the air. So sometimes that can that also have the mix with the water vapors. So while selecting the compressor and for the fermentation need we have to be very careful because as concern the instrument air that the compressor is not used. So our air should be the oil free and we have to use those compressors which produce oil free air with the required pressure. So as concern the automatic control of the compressor either that how much is the pressure inside the container in which the air is stored and then is there any filter just to check the supply of that air free from the oil. And then so we can see that if there is an automatic control just to maintain that pressure that we required and then the actual quality of the air that we need for the fermentation process though so the compressor and the next system is very critical while having the oxygen delivery system in a fermenter of any kind of fermentation. . . .