 Welcome to this lecture 21 in the module on Pollution and Quality Analysis of Groundwater. And so in this we will discuss with the meaning of pollution first and this pollution it is the artificial deterioration in the natural groundwater quality. So obviously in this we are focusing on the deterioration or decline which has come in the natural in the quality of natural groundwater by artificial means. And here we should make a distinction between pollution and contamination. So here this contamination is a pollution which is hazardous to human health. So contamination is also a type of pollution only and here so it causes the hazard or a danger it provides a danger it poses a danger to the human health whereas pollution it may or may not pose a danger to the human health. So once it poses a danger to the human health then it is known as contamination. And there are various sources of pollution of groundwater. So here let us briefly discuss the that is the types of groundwater pollution. So this groundwater pollution so it can be classified into various categories based on various criteria like say the classification based on sources based on the sources of pollution of groundwater. So we can classify into this is a groundwater pollution due to municipal sources and then followed by the groundwater pollution due to industrial sources then the next category of groundwater pollution is the groundwater pollution due to agricultural sources and then lastly the groundwater pollution due to miscellaneous and other sources and based on the geometry so this groundwater pollution can be classified into that is the point sources of groundwater pollution and this is the next category is the area sources of groundwater pollution and of course here this is a line sources of this groundwater pollution. So this area as well as line sources of groundwater pollution so they are also known as non-point sources for groundwater pollution so GW is abbreviation for groundwater so this is groundwater pollution or they are also known as distributed or diffused distributed sources of groundwater pollution and here and again so this point sources of pollution we can further group this into further categorize this into groundwater pollution due to L napples of course I will give you the expansion of this just a minute later. Next is groundwater pollution due to D napples and lastly the groundwater pollution due to inorganics and others so all this is part of the all this comes under point sources of pollution so here this L napple so this L napple is the light non-aqueous face liquid similarly D napple is dense non-aqueous face liquid so here this L napple you can give the example of say it is petroleum products and this crude oil etc and D napple so this is the example you can give is the dry cleaning pollutants, automobile pollutants like the engine oil etc the aviation pollutants the pollutants which are used in the aviation sector then the electric circuit board pollutants so all these are heavier than water so therefore they are included in this dense non-aqueous face liquid face liquids whereas this petroleum products so that is this crude oil etc like petrol, diesel, kerosene and all this so they are lighter than water so therefore they are included in this light non-aqueous face liquid or say L napple here and since they are light so they will be in the they will be spread on the water table whereas this dense this D napples because they are heavier than this one so they move or they infiltrate further below the water table and they form that is dense plumes within the aquifer below the water table and then this so this inorganics or others so they consist of metals salts etc so these are the some of the this one and if the sources of pollution so they are not restricted to a point so then they are known as diffused or distributed source of pollution and in this case so the pollution source may be extended over a line or it may be distributed over an area either in a plane or in a three dimensional source okay so in that case all of them are included as non-point sources of ground water pollution so this is the classification based on the geometry whereas the classification based on the sources is it is a 4 fold classification starting with the municipal sources of ground water pollution followed by industrial sources agricultural sources and then this the miscellaneous or other sources of pollution now let us discuss the municipal sources of ground water pollution in this so we will be we will be covering that is the sewer leakage followed by liquid waste followed by solid waste so these are the three categories and now let us discuss the municipal sources of ground water pollution and here in the municipal sources of ground water pollution let us go to what happens when water is used for domestic uses the effects of effects of domestic water use obviously so all this when water is used for domestic purpose so it can be for an inside use or it can also be for an outside use so within the inside use that means within the buildings or any other facilities so here it can be so this is this chart is taken from Hassan 1974 at which so there is a very good categorization of the effect of domestic use so here the inside use it will result in say waste water it may also result in say solid waste so the solid waste are also generated when it is used for outside use and here so in the outside use and the water is used outside so it may be it may go as a recharge into ground water basins or it may go into storm drains or storm water drains then this waste water so it can be it can go into septic tanks or it can also go this move through this sewers into say this treatment plants the solid waste they will go to sanitary landfills and the storm water drains it may either go to ocean outfall of course ocean is the last as one may be before that it may be getting discharged into various streams or rivers or seas or estuaries oceans and then this one so this recharge into ground water basin so part of it may enter this recharge it may enter this recharge into the ground water basin and here so from this treatment plant so it may go to surface water streams and from this surface water streams so it may go to this ocean outfalls or part of it may recharge into the ground water basin and then so part of this treatment plant the water which is the waste water which goes to the treatment plant may go to that is reuse of water part of it may be reused after thorough treatment or part of it may result in the formation of sludges and again so this from the septic tank also so part of it may go to sludges and then so this part of it may go to recharge into ground water basins and these sludges may either go to sanitary landfills or they may go to sludge lagoons or they may go to ocean outfalls so this is the total flowchart of the effects of water when it is used for say domestic purpose so whether it is used within a building or in for whether it is used for an indoor purpose or an outdoor purpose so this is it may create waste water solid waste or when it is used for outdoor purpose it may cause solid waste recharge into ground water basin or storm water drains like that and here so this so in this indoor use of course so here you can say this is approximately 50 percent and then this outdoor use which is say for lawn watering or pesticides or car wash or may be swimming pool so that is also been approximately estimated as say 50 percent of the total domestic water use so this is how the when water is used for domestic purpose so this is how these are the various locations where it may move so now let us consider the the sewer leakage which is so this sewer leakage it is one of the main causes of municipal pollution of ground water pollution due to municipal uses so here the sewer leakage may be due to that is let us say the causes of sewer leakage are poor workmanship or it may be defective sewer pipe or it may be due to damage by tree roots or plant roots or it may be damaged by say earthquake damage or rupture by heavy loads or soil slippage it may also be so that is loss of foundation support in that case the sewer may show a damage it may show a crack or a breakage or or it may also be due to shearing caused by differential settlement in manholes say near manholes it may be due to infiltration of sewage into abandoned sewers sewer laterals so these are the various causes so like the first one is a poor workmanship the second one is the defective sewer pipe the third one is a damage caused by plant roots the fourth one is damage caused by earthquake the fifth one is the damage caused by heavy loads or soil slippage the sixth one is the loss of foundation supports the seventh one is the shearing caused by differential settlement near in or near manholes and then this infiltration of sewage into abandoned sewer laterals etc so these are some of the causes of sewer leakage. Now let us consider the second main type of the municipal the groundwater pollution due to municipal causes that is the liquid waste and we all know that this waste water is having a significant amount of liquid content and this what happens is so this waste water which is generated by this municipal use of water and it results in a significant amount of that is pollution of groundwater and these liquid waste move as per the groundwater flow directions so these are the so this is the waste water or we can say the domestic waste water that is the municipal waste water flow as per the gradient or the groundwater flow gradient so this leads to this cause the second category of the municipal pollution of groundwater and then the last this one is the last cause of the groundwater pollution due to municipal sources occurs due to say solid waste. So, here the solid waste are in solid form and then so they are basically dumped into the landfill so this solid waste dumped in landfills cause the leachate into groundwater and especially when there is a so the especially when there is a rainfall or a shallow water table the pollution of groundwater by municipal sources due to solid waste is the maximum so as long as the there is no rainfall or the water table is at an appropriate depth so then so there is there will not be much of a pollution or from the solid waste, but as and when there is some amount of rainfall or precipitation or this over the wherever there is a very shallow groundwater table so this leachate from the landfills so it starts flowing and it causes the groundwater pollution so these are so the sewer leakage the liquid waste as well as solid waste so they constitute most of the groundwater pollution due to municipal causes. Now let us come to the groundwater pollution by industrial causes so here from the same source by Hassan et al. let us discuss the effects of water for industrial use so here in this industrial use again the sources for this also the source is the same publication by Hassan in 1974 so in which there is a very good this flow chart is given of the effects of water from industrial use so when the water is used for industrial purposes it may result in mainly three effects the first one is the sanitation use for cleaning purpose and the second one is the manufacturing and processing use and then thirdly it is water is used in the industry for cooling purpose or cooling uses so here and all this all the three uses result in this what are known as the industrial waste whether the water is used for either the sanitation or the cleaning purpose or manufacturing or processing purpose or for cooling purpose it all results in the industrial waste. Then so these industrial waste they may result either non-reclamable wastewater whose reclamation is almost impossible or economically not feasible or it may result in the industrial waste they may also result in say solid waste such as a fly ash or other kinds of this solid waste or part of it may be reclamationable which can be reclaimed after treatment so that is so this reclamationable waste water and here so this part of the water which is used for cooling purpose it also evaporates. So now this non-reclamable wastewater again it has 3 roots it may either go to ocean outfalls it may go to a sanitary landfill or it may go to that is deep aquifer injection. So this solid waste so this also may go to ocean outfall or it may go to a sanitary landfill it may go to a sludge lagoon and this reclamable wastewater so this is it may follow any of the 3 paths the first one is the recycled water again for industrial use then it may go to say municipal treatment plant it may go to disposal in streams or rivers and then this municipal treatment plants so from this municipal treatment plants it may go to sludge lagoon or it may go to say reusable water or it may be recharge into groundwater basins or lastly it may go to surface water streams. So these are the various types of movement of the one of the industrial the groundwater pollution caused by the industrial uses and again here so this groundwater pollution caused by industrial uses so they have been mainly categorized as say liquid waste or tank and pipeline leakages or the wastes from mining activities and here so coming to the liquid waste so these are basically the liquid form of the industrial wastewater so it flows along with the groundwater flow gradient and then it will cause eventually it might cause groundwater pollution. Coming to this tank and pipeline leakages so here so this is this happens due to leakages from tanks and pipelines so in this case an immiscible liquid immiscible liquid such as oil moves till it reaches water table and coming to the waste from mining activities so there are multiple waste types of waste are generated from the mining activities so there is one last category is there that is the oil field brines so that is the heavily saline solutions which are released from the oil fields. So these are the four categories which result in the groundwater pollution due to industrial causes and here so the when you talk of this an immiscible liquid such as an oil so here what happens is say if the liquid is immiscible then it forms a layer so here say suppose this is the ground surface and then this is the spill area and the plume so this is the spill area and then so here so this is the water table this is the residual saturation and over this so this liquid waste spreads on top of the water table and then so here if this is the direction of the water movement so this is the below the ground water table then so this one the oil also moves along with the slowly along with the ground water at the top of the water table and then causes ground water pollution. And also suppose if such a case exist of such a case of ground water pollution due to industrial use exist then we can remove this liquid pollutant from this from a pumping well say suppose within this ground water and drill a pumping well this is the water table and the oil which is spilled here which has spread on the ground water and here we can show this is the from the spill area so this is the residual saturation then this is the oil and then so using so and then this is the pumping well so this is possible only when this oil is immiscible. So when the oil is immiscible so obviously it will spread on the top of the water table and then it can be pumped out so this is one way then coming to this oil field brines so in this case because brine is a very saline solution of wastewater saline solution of water so here what happens is it spreads and then so this it will increase salinity and so therefore it needs to be tackled in a different way so this pumping kind of treatment so may not be suitable for that so in the next lecture we will discuss about the ground water pollution by agricultural sources as well as the miscellaneous sources thank you.