 In this module we will talk about the filter sterilization but before this module as you know that we discussed about the sterilization process by heat either by the direct heat or by the wet heat using the steam but in this module we will talk about the filter sterilization. Before talking the filter sterilization we will just try to know that what are the basic principles and the technique used for the filtration. So as concerned the filtration the suspended solids may be separated from a liquid during the filtration by following mechanism. The first mechanism can be inertial impactions and the second one is diffusion and the third is electrostatic attractions and the fourth is interception. So these four different mechanism can be involved in the filtration process either that will be a simple filtration either that will be involved the filtration for the sterilization. Mostly when we say the filtration then the actual method is then something has to pass through a membrane. So we will talk about step by step about all these mechanisms involved in the filtration. First one is the inertial impaction. So what is inertial impaction? In this the suspended particles in the fluid stream have the momentum. So the fluid in which the particles are suspended will flow through a filter by the root of least resistance. So somewhere is high resistance and somewhere is least resistance. However the particles because of their momentum tend to travel in a straight lines and may therefore become impacted upon the fibers where they may be then remain. So inertial impaction is more significant in the filtration of the gas than in the filtration of the liquids. So inertial impaction is basically depend upon the resistance. So as concerned the diffusion mechanism. So when the diffusion is when extremely small particles which we called as the suspended particles in a fluid are subjected to the Brownian motions which is random and we know that the Brownian movement are the randomly random movements. So due to the collision with the fluid molecules so thus such particles tend to deviate from the fluid flow pattern. So if the fluid flow is having a specific flow pattern then when there is a collision then they deviate that the flow pattern. So that may become impacted upon the filter fibers. So when there is a collision with the filter fibers so then the diffusion is more significant in the filtration of the gases than in the filtration of the liquid. So the inertial impaction and the diffusion both mechanisms are mostly applicable when we are dealing with the filtration of the gaseous material or a gaseous phase. So as concerned the third mechanism which is electrostatic attraction. In this the charge particles may be attracted by the opposite charges on the surface of the filtration medium. So because if there is a charge that the filter we are using having the different charge and the particle which we have to be filtered then that have an other charges. So the electrostatic attractions are basically depend upon the charge particles. So as concerned the fourth mechanism which one is the interception. So the fiber comprising a filter are interwoven to a defined opening of the various sizes. So the particles which are larger than the filter pores are removed by direct interception. Mostly this interception is mostly the mechanism that is involved in simple filtration process. So the significant number of the particles which are smaller than the filter pores are also retained by the interception. So this may occur by the several mechanism. So more than one particles may arrive at the pore simultaneously. And irregular shaped particles may bridge a pore. Once a particle has been trapped by the mechanism other than the interception the pores may be partially accolade, accoladed enabling the entrapment of the smaller molecules. So the interception is equally important mechanism in the filtration of the gases as well as the liquids. So these are the different four mechanism which are involved in the filtration process. The first two is mostly applied for the gases but the electrostatic attraction and the interception can be involved in both cases as well as the gases as well as the. So as concerned the filtration are the filters. So the filters types is classified into two types. So the first one in which those the pores of the filter are smaller than the particles which are to be removed. Another case is the vice versa when the pores are larger than the particles. So these are the two different types of the filters which one can use for filter sterilization. So in next step we will try to know that what actually is the process of filter sterilization in our later modules. Thank you.