 Greetings, students. My name is Mahirubhale. I am an assistant professor in the Civil Department of WIT, Sallapur. Today, we are going to study about fluidized aerobic bed technology. So, what is the learning outcome? At the end of the session, students will be able to understand the concept of fluidized aerobic bed technology. Fluidized beds are basically a kind of a bed which can be used in aerobic, analgesic or anaerobic digesters. It depends on whether we are providing oxygen to it or not. Basically, it is a combination of attached growth and suspended process. In which reactor is kind of a cylindrical and having its perforations by which the water can come in. There is a proper conical entry sections by which water can come in. It is also having a biological film which is developed and maintained on solid support medium. This solid support medium can be a type of a particulates typically it is called as bioparticles in which the microorganisms can grow. A support medium maintained in suspension by upward flow of influence. The water is flown inside in such a way that whatever the particles which are acting as a bed for the microorganisms, they will be continuously in the suspension. It happens that the water is continuously flown from the bottom to upside. Therefore, whatever the bioparticles which are present or media which is present is continuously in the suspension. Fabricated media is always developed to support biomass growth within the porous internal structure. So let us see its diagram. If you see the diagram, you will get to understand the water including the air is made to push inside the reactor. It is typically cylindrical shape in which the depth is kept very much larger than the surface area. Here, as the water is made to push at that velocity which can overcome the gravitational pull, therefore the media will be kept continuously in the suspension. As the water passes, whatever the organic matter which is present in the west water will get attached to the media and automatically the biodegradation process takes place. So here you can see the solids meets the bioparticles or the media is made to come inside the bioreactor. Automatically, whatever the gases which are produced like carbon dioxide, like methane, if it is happening, then such type of gases is taken out from the upside. So now as the treatment is going on, if you can understand, the media is continuously in the suspension. So automatically, if we are providing some irregular media or having the large surface area, so automatically the biodegradation or the metabolism process takes place at a faster rate. Therefore, the organic matter can be easily degradable with a lesser HRT or lesser detention time. Therefore, this type of a process is always giving out the lesser HRT time. Similarly, the efficiency is also going to be higher because large surface area of the bioparticles or the media always gives out the higher rate of degradation. Therefore, the higher efficiency can be easily achieved. Now, whatever the effluent which is being prescribed as per the detention time is being taken out, it is taken care that no the bioparticle is allowed to pass through a membrane. Therefore, only effluent can come out. This is the basic principle of fluidized aerobic bed technology. So what is its main point by which this kind of a technology is very much famous? It always provides the large specific surface area. It means the media is having higher surface area. Automatically, the fast biofilm can be formed on that media like MBBR. Automatically, effective simple control on the biofilm can be there. So if the thickness is going to be increased, we can take out some media, we can clean it up and again we can add it into that bed technology. So it is simpler to maintain also. These are the points which I have talked till now. If you want, please pause the video, take a screenshot or write it down the notes. I will go forward. This is the typical two-phase fluidized bed reactor in which solids and liquid that is wastewater is present in the bioreactor. If you see on the left part diagram, you will get to understand no air is been provided inside the bioreactor. But only two-phase that is solid and liquid is been put inside. Now what happens? Air is made to push inside such type of reactor with the influent. What happens? As we have to provide a large velocity of wastewater, some part of the influent again we have to recycle. Otherwise, no biofilm, MLSS will be maintained inside the reactor. The rotors have been provided and it has been rotated with the help of motor so that the media is continuously being in the suspension. Whatever the detention time which has been prescribed, at that point the effluent is taken out. Now, here the question is whether the influent is made to flow should be greater than gravitational pull? So for the two-phase system, it doesn't happen like that. Therefore, what we do? See on the right side picture, we add up air for the recirculation of effluent. Some part of the effluent is made to recirculate in which the influent is also getting added and air is also getting added. Therefore, the velocity which can overcome the gravitational pull can be easily maintained. Now, in this system, you can understand no additional motor has been provided. Therefore, whatever the biomass which is in suspension will not be get othered or will not be get hampered and they will not get continuously hit with each other and the biomass is getting formed very much quickly and they will be maintained. If suppose air is included in that and if you make the three-phase system, automatically the air will make the biomass to hit to each other and automatically whatever the layer of microorganisms which has been formed on the media will automatically get outside from the otherment and they will get settled at downside and automatically the MLSS concentration decreases. Therefore, such type of a system is a good system. Now, if the MLSS is going to be increased, some part of the biomass is taken out or the bioparticles are taken out, they are made to clear up and again they are added in. Therefore, the MLSS is easily maintained. All these points I have talked is presented in the screen. So, please pause this video, take a screenshot and again I will resume it. Now, there are new developments happening in the fluidized aerobic bed technology in which the three-phase system has been trying out, in which all the three phases like solid, liquid and gas is being added in it. In the earlier two phases, air used to be added with the influence but here you can see on the left side diagram, you will get to understand the air is additionally added in the fluidized aerobic bed technology. Here what they had done in this bioreactor, they have again inserted a smaller cylindrical pipe inside the bioreactor. It means as the air pushes in the media which is present inside it, it will use the full 100% volume of the reactor. But as we have to recirculate the effluent so that the velocity can be maintained, some part of the effluent is made to push inside that thin cylinder that effluent is made to revisit outside that inner cylinder. Therefore, the effluent is continuously rotated inside the bioreactor. Now, you can see also here the three-phase system has been also provided which is separating solids, liquids and gas. But the problem here is as we are providing a lot of air, if you see on the right side picture, you will get to understand we are providing a lot of air so that the biomedias should remain in the suspension. These air will try to stick into the biobarticles or the biomass or the media and the media will again stick each other or hit each other and the thick biomass which have been formed on the media will separate out and easily the efficiency will go down. Typically in the two-phase system which we had seen earlier, it is giving around the efficiency higher than this three-phase system. Why? Because of the same limitation. So all these things which I have said now is being written here. So please pause this video, take a screenshot of that screen or note it down and I will resume the video. Same thing here also. Whatever the points which I have told you in the three-phase system has been written here, please pause this video, take a screenshot or write it down the notes and I will resume the video now. So what are the advantages of fluidized aerobic bed technology? First one, low biomass sludge production. High biomass concentration will be there in the reactor. High strength wastewater treatment can be easily possible. Then low-stretch transport or disposal can be easily done. High exposure to liquid biofilm surface area. It means large amount of surface area can be easily provided here. And it is having very much low operational cost. So what are the applications? Aerobic FBR, that is fluidized aerobic bed technology reactor is used for nitrate removal in petroleum industry, co-plant, explosive factory or the nuclear plant. Anoxic FBR can also be used for denitrification. So let us have few review questions. First one, the substance used in fluidized bed is as same as packed bed, powered substance, large balls or finely divided solid material. Second one, fluidized beds are always used in vertical arrangement, whether this statement is true or false. The pressure drop in fluidized bed on fluidization is dashed with increasing flow rate. It remains same, linearly increases, linearly decreases or remains zero. So let us see their answers. For the first it is finely divided solid material. Fluidized beds are always used in a vertical arrangement as the fluidized bed technology is a kind of a vertical system so this statement is very much true. The pressure drop in fluidized bed on fluidization is always remains same with increasing flow rate. These are the references I have used to make this video. Thank you.