 In this module, we will talk about the sterilization or the removal of viable organisms from the exhaust air. But as concern our previous module, we will talk, we talked about the air sterilization that is needed to be added into the fermentation just for aerobic fermentation. But as we know that for the better containment level and we have very strict regulation then there is need to remove all those viable cells from the exhaust air. Because if we are dealing with some pathogenic organism then we have to assure that the gases exhausted from the fermentation vessel should be free from the microorganism. But in this case when we are dealing with the exhaust air then the problem is that air is mostly wet because when that passes through the fermentation medium that contains some water vapors because the whole medium is liquid. So in many traditional fermentation the exhaust gas from the fermenter was vented without sterilization or vented through relatively inefficient depth filters. So with the advent of the use of recombinant organisms and a greater awareness of the safety and the mission levels of the allergic compounds, the containment of exhaust air is more common and in case of the recombinant organism become very compulsory. So this is the issue when we are dealing with the sterilization of the exhaust air. So the fixed pore membrane modules are also used for this application. But the system must be able to go with the sterilization of the water saturated air as I have already told you that the exhaust air is having the saturated water content. So at relatively high temperature and carrying a large contamination level. So also the foam may overflow from the fermenter into the exhaust air. So these are very limitation when we are selecting the sterilization process of the exhaust air. So thus some from the pre-treatment of the exhaust gas is necessary before it entered into the absolute filter because if we directly allow the exhaust air to pass through the filter then there is the chance of the blockage due to the water vapors due to the other media content contained into that water into that air. So we have to use some pre-filters or some treatment just to remove the water or some condensation processes in which the most of the water molecules become condensed just to remain inside the fermentation vessel. So this pre-treatment may be hydrophobic pre-filters or a mechanical separate to remove the water aerosol particles and the foam. So the pre-treated air is then fed into 0.2 micron hydrophobic filter as we have already discussed that PTF the filters. So it is important to appreciate that the filtration system must be steam sterilized as well as the inlet and the outlet. So in next slide you will see that that how this whole system having the mechanical separator system designed. So in this slide you can see that in this first diagram you can see here is the fermenter and this one is the exhaust air that how that come and if there is a condensation of the water that come back to the fermenter and then this air is goes to by this line and here is the heater and then is this one is actually the filter which we called as PTF filter just to sterilize the air and then the air oozes out. And in this diagram you can see that how this one is the fermenter and you can see that this is the whole or the fermenter vessel. So this is the different so first one this pass through a condenser. So this is the coil and all the water which is condense here then that would be drop down into the fermentation vessel. Then that go into turbosap in this chamber and then again if there is a condensation then go back. So then the air by this here is the heater and then just to make sure the death of that. So then here is the filter. So you can see here that how this will be controlled because this filter required the sterilization pre sterilization. So there is the automatic on and off wall. So this is the inlet and then this whole chamber and then there is the outside. So this whole system you can see that a mechanical separator and hydrophobic filter system for sterilization of the off gas from the fermenter. So you can see that how this exhaust air is necessary to be sterilized and what is the possible mechanism to use the pre-filter and pre-treatment before treating the exhaust gas for sterilization. So you can see here in again that the dual hydrophobic filter system for the sterilization of the off gas. So here is the fermenter and then you can see that is the pre-filter and then steam in the barrier filter and then the steam goes out. So this is the whole story of the sterilization that in each and every step sterilization is very critical. So the fermentation process without sterilization is nothing because we are only allowed to grow the organism of which we called as process organism. But after the fermentation when there is a down streaming then there is the need of the proper disposal of the waste which we called as the remaining broth other than the product and then we have to maintain all the containment regulations just by killing the process organism for the better environment.