 Hello everyone, I am Swati Ghadge, Assistant Professor, Department of Civil Engineering from WIT, Solarpur. Topic for today's session is Waste Water Treatment System. Learning outcome of this session, at the end of this session, learner will be able to explain water treatment process. This is a sewer system which is collecting sewage from the individual houses and at last the sewage of entire city is collected in a main sewer. In earlier days, it is directly disposed in a natural source of water, say river or sea. It causes water pollution or river pollution. It also affects aquatic life. So before disposal, it must be treated. Let's see the treatment of wastewater. So this is a flowchart of treatment of wastewater. First it is collected from the residential area as well as industrial area. Then before treatment, it must be pre-treated. That is the first unit of pre-treatment is a screening chamber. In this screening chamber, removal of insoluble floating material takes place. Say water bottle, plastic bags, they are removed from the water. Then sewage has all type of impurities. It has oil, grease, soap, some grit chamber. So they are removed in the second unit called as grit chamber. Grease and oil floats on the water and grit particle settle down at the bottom. So from the top, oil and grease get removed and from the bottom, grit particle are removed. After pre-treatment, water goes for the primary treatment. In the primary treatment, sedimentation occurs. Sedimentation of heavy particle that settle down at the bottom due to gravity and it is removed from the bottom. After the primary treatment, that wastewater goes for the aeration. In the aeration, oxygen involved in the sample and it purifies it. It removes some dissolved gases. After that, it goes for the secondary treatment that is clarifier. Concept of clarifier and the sedimentation is same that heavy particle, heavy dust particle due to sulphate settle down at the bottom and from the bottom it removes. Before aeration, there is a primary treatment called as sedimentation and after aeration, there is a secondary treatment called as clarification. The sludge we get from the primary treatment is called as the primary sludge and the sludge we get from the secondary treatment called as secondary sludge. After clarification, there is a treatment called as chlorination. chlorination is nothing but the addition of cloning in water to avoid the spread of water bond disease. After chlorification water is treated up to the drinkable level and then it may dispose in a source of water or it may use for the agriculture purpose. This is a alternate flow chart. This is the pre-treatment then after pre-treatment it goes for the primary treatment that is called as the primary clarifier, then aeration, then secondary clarifier and then after secondary clarification it goes for the chlorination and then finally it is ready to dispose where it has to dispose. So the sludge we get from the primary treatment it is called as the primary sludge then sludge is also go for some treatment and then it is dispose. Then here the sludge we get from the secondary treatment that called as the activated sludge and it again go for some treatment and after treatment it may dispose. This is the 3D diagram from where it is more clear how the wastewater treated. So the operation number one, wastewater or sewage is pumped underground to the lifting station where it is chemically treated and sent for the separation. The separation process filter out solid larger than 13 mm. So the solid send dispose dump here and the liquid go in the station number three. Station number three is the primary settling basin which allow heavier material to sink and be scrapped away. The waste is then fermented for 30 days. This is the fermentation tank here the solid waste fermented for the 30 days. It gives us fertilizer see that truck is carrying fertilizer and the liquid will come in the tank number four. In that the bacteria break down the harmful matter and the more clear water will go in the station five. So the station five is the secondary clarifiers that is nothing but the sedimentation. Heavy particles settle down at the bottom and clean water will go for the chlorination that is station number six. In station number six the water is finally chemically treated with the chlorine to ensure it is free from the bacteria. And it is passes over a wear and into the water supply. These are the some basic definition. First is the screening chamber. It is the first unit operation of best water treatment plant that separate larger insoluble floating material from sewage. Second is the aeration. It is a physical process which brings water and oxygen in close contact in order to remove dissolved gases. Dissolved gases say CO2, H2S, CH4 etc. Third is the sedimentation. It is a physical water treatment process which remove suspended solid from waste water using gravity. Clarifier. It is generally used to remove solid particle or suspended solid from liquid for clarification. And last is the chlorination. It is a process of adding chlorine to the water to kill pathogenic bacteria present in water. You have seen a flow chart, we have seen a theoretical definition. If you see the images it is more clear that how it actually happen. This is the image of screen chamber. So all the floating particles remove primarily by this screen. This is a grid chamber. On the grid chamber some primary level sedimentation occur and so large heavy particle removed here and some floating oil or grease removed from the top. This is the third operation called sedimentation. See here all the heavy particles due to gravity are settling down at the bottom. For this process the flow rate of water makes it slower so that it allows some heavy particles settle down. Now you pause the video here and answer the question. Which is the correct flow of sewage in waste water treatment plant? So there are four options. There are four flow chart. You select correct flow chart of waste water treatment. Answer is first option is the correct option. First screening happens then grid chamber then sedimentation tank and then chlorination. So we have seen sedimentation. Now the next is the aeration. Aeration means bring water in close contact with oxygen so it purifies it. So see here at the bottom air getting involved in this sample. And here you can see the air bubbles formations are there so it purifies the waste water. After that there is a secondary treatment called as clarification. This is the clarifier. Here this is the inlet from where the sample entered in the tank. At the bottom there is one arm which is rotating after some interval of time. So it collect all the solid waste which is collected at the bottom and through that pipe it is discharged. And it is rotating so water is also rotating and at the top we get the pure water and it has an outlet at the top. And there is a provision of bridge for the walkway. It is just for the supervision to keep a watch on this tank. This is what how the clarifier looks like. After clarification there is a process called chlorination. This is a picture of chlorination tank. And after chlorination water is treated and then it is ready for the disposal. So it may dispose in a natural source of water or that pure water may use for the agriculture purpose or some other purpose. These are my references for this video. Thank you very much for watching.