 These are the examples of municipal waste, compost. Compost is nothing but a manure, how it is formed, the composition of organic waste. Any example, not cow dung basically, it has to be leaves, vegetables, bio organisms and how do you form compost, anybody does gardening here, you do, have you ever formed compost in your garden, that is right, well this is a miniature landfill. So, what you do in a big landfill is the same activity at a larger scale, which you are doing in your kitchen garden, the whole idea is to degrade the waste and by degradation what is that you are achieving, you are lowering the volume of the waste which has been created. So, one agenda which is in the mind is when you deal with waste management issues and how to reduce the volume of the waste which is coming out of the industries, clear. So, it is a good example, compost. In IIT, I think we are adopting this technique, so you might have seen people in the morning they keep on grooming the roads and they collect leaves and all. So, ultimately where do they throw all the leaves, so they collect it and they dump it somewhere where they produce lot of manure for the entire campus. So, what is scrap tyres, what is meant by scrap tyres, used tyres, so India is becoming a major market for car companies, so apart from traffic congestion, what is the biggest threat, disposal of tyres, so every third year or fourth year when you go for servicing of the car, they say you change the tyres, so it is very easy to say change the tyres, so ultimately where you are going to dump these tyres. So, this is where scrap tyres becomes very important and most of the geotechnical engineers have you know got some good answers to this problems. Any guess what they are doing with this? See, I am not in favor of distracting the matrix of the soil first, adding something and re-compacting it. So, those who belong to this school of thought they should be careful, see natural soil is the most stable condition of the soil, clear. And the issue is you may dig out the soil, but where you are going to keep it in a city like Bombay, where there is no place to even to keep the soil by digging it out of the pit, how you are going to mix something into it. And the larger interest you will see in my subsequent discussions that scrap tyres have been used by people in making embankments, roads, domestic asphalt and so on, shredded asphalt, you know they mix asphalt and scrap tyre chips. I will demonstrate to you one of the methodologies of using these scrap tyres for making pavements in next class or may be today's lecture depending upon the time. So, scrap tyres are becoming a very big issue, I will discuss about this used oil, engine oils that is right. So, most of the car companies they are very particular that the engine oil should be changed every 6 months, did you ever ask your automobile dealer that why it should be done and ultimately what you do with this oil you should ask next time, it is a big technology and a million dollar industry, you know this it is not so easy to talk about what engine oil does to the engine. As I understand whatever you have said is ok, if you go into the too much technicalities engine oil should stop the abrasion of cylinders, so it should be anti abrasion. Same thing is it should be thermally stable, it should lower down the temperature, otherwise what will happen the engine cylinders themselves will get corroded. So, it is a big science when you say like we visited one industry in Bombay and the fellow says that he is the only one in Asia I suppose who produces engine oil and the type of waste which is generating we are trying to utilize it somewhere else we are trying to study the property of that waste. If you get some time we may plan a visit there as basically the industry which produces 2 teeth for the engines, apart from engine oils what type of oils you can think of sorry that is not very severe. I think good example should be transformer oil which is a big challenge because of oil after certain time becomes spent oil that means, its dielectric constant keeps on changing the more and more you use it. So, it will never behave like a insulator unless you recycle it clean it or you know process it. So, the more and more civilization is taking place what is happening the society is producing more and more scrap tires more and more used oil ultimately where you are going to throw it, where you are going to stack it, how you are going to recycle it, how you are going to clean it. So, these are becoming you know very important challenges you may take some seminars topics from today's discussions. Sea waste sludge I think somebody was talking about this sludge which comes out of the I think Sneha was talking about this sea waste sludge. Yes this is also one of the types of municipal waste, water treatment sludge, purification of the sludge which comes out of the water treatment plants. So, these are of low hazardicity. Again the question is you use the word low and high and medium what is the scale clear. So, as on date there is no scale as such where you can define what is meant by low high and medium of course, these are all abstract thinking, but the idea is simple that their intensity is not much well as you can make out from the list of industrial non hazardous waste coal ash that is the fly ash or bottom ash. Some people classify coal ash as non hazardous, some may classify it as hazardous what should be the difference between the two. As you said rightly that it is airborne, it gets airborne and then it may cause carcinogenic effects you know if you breathe in your lungs may get affected, there could be lot of loss of visibility in the neighborhood, it could form a dust and so on. But suppose if I say it is non hazardous, have you heard of TCLP test in your environmental engineering courses, did they talk about TCLP? No. So, it is a test basically which talks about how much concentration of a contaminant will leach out of a material. So, based on the leachability of the material, we can also classify this as a hazardous and non hazardous. So, these things you will study slightly later. So, based on toxicity that means the amount of toxic elements which are associated with the waste, hazardousity the amount of hazardous materials which are associated with the waste and so on. If your coal ashes are not leaching, when they come in contact with water that means no heavy metals are leaching out of the waste matrix, it is non hazardous. But if the ash has a tendency to leach different metal ions, it becomes hazardous and toxic. So, what is the difference between hazardousity and toxicity? If I take certain concentration of a contaminant clear, it could be highly toxic. If I dilute it, it becomes less toxic. If I keep on diluting it, it becomes less, less, less, less toxic, very less toxic. If I further dilute it, what happens? It becomes non toxic, you got this point. So, basically depending upon the concentration of the toxic materials which are present in the system, you may say whether it is toxic hazardous or toxic, non hazardous is not possible because toxicity is available is already associated. So, toxicity itself is hazardous, but its magnitude depends upon the concentration of the waste. So, this philosophy basically helps you in designing the code of conduct for the society and for different countries, you got the idea. So, based on this concept, certain industrial process whether it is going to be toxic or non hazardous, hazardous is going to be determined. Most of the ferrous and non ferrous legs are under the category of non hazardous waste. So, when we are talking about non hazardous city of the waste, can you think of a situation where you would like to use it? When we are saying that certain waste are non hazardous, where can you use the GGBFS? So, they may go either in construction or as the foundation material or as the film material that is right, but if your ash is active and if it is going to interact by any chance with the groundwater or the rain water, then you cannot take this chance. So, based on this consideration, you can use the material at the appropriate place. This is a very big concern, particularly when you talk about application of fly ash for mine closures. So, if ash is reacting with water and if leachability is very high, you cannot use it for filling the mines, but if it is a passive material, there is no harm. So, based on this concept, Government of India had come up with some regulations that every power plant requires coal. So, there was a sort of a condition that we will buy coal from a mine, we will buy the coal, but the ash which is getting produced should be taken back to the mine and the mine should be filled up. So, this has become now a code of compliance. So, this is how the codes are formed related to activities which may cause enough toxicity or hazardicity in the environment. Is this part clear? The third application, third example is reclaimed paving materials, mostly construction materials which are used as a paving material, WBM mostly. Construction and demolition debris, I think we have talked about this in the earlier lecture. In city like Bombay or all metros, mega cities, the biggest challenge is every now and then you have to go for reconstruction of the buildings. So, the biggest issue is we have to throw the demolition or the construction debris. By the way, the road connecting to Eastern Express highway and LBS mark, this was done based on the construction debris only. So, 2000, I think they started dumping debris on both the sides of the roads. So, where you fly off right now, it is nothing but the foundations are laid with construction and demolition debris. They have consolidated over a period of time, two, three years, four years and now they have constructed the whole pavement over it. Earlier it was nothing but a marshy land. Cement and lime can desist. Again, you can use this as a construction material part replacement of construction material which are normally used in concrete. Sulphates, any example of sulphate which comes to your mind which is very challenging, sorry, phospho gypsum. Phospho gypsum is a good example of the type of sulphates which you talk about, is it not. So, sulphuric acid and then it comes in concrete with calcium sulphates. Sulphur trioxide fumes have to be captured so that they do not go into the environment. So, this is where you create enough phospho gypsum. Phospho gypsum is also a very hot topic for research in environmental geotechnology. Foundry, ceramic, silica fumes. We have talked about silica fumes earlier. So, silica fume is nothing but a sort of a byproduct which comes out of these industries which are manufacturing, what, sorry, alumina. It is a mesonomer. When you say silica fume, it is truly a mesonomer which is associated with aluminum industry. Dredged material, we are involved with the project right now. We are doing it for JNPT where JNPT has asked us to study the properties of the material which can be used for reclaiming land from the sea. When we talk about reclaiming land, it is about say 200 hectares which has to be reclaimed from the sea so that one more terminal for the ships can be generated. This is becoming a very good subject in geotechnical engineering. Reclamation of land, particularly when you go to Singapore or some other Norwegian countries where land is scarce, Japan, Malaysia, Indonesia. So, this is where this industry is flourishing a lot and it has very good scope for people who want to do something new. So, the biggest question is when you, why do you do dredging? Are you aware of what is dredging activity? Yeah, this is a very old school of thought. Nowadays, as I said you do any activity as long as you are not hampering others freedom you know it is ok. But when the moment you say I will dress something here and I will dump it somewhere the question is where you are going to dump it? Who is going to allow you to do that? So, if you have been reading the newspaper the Victoria Docks at Bombay Port Trust. It is a huge land which is abandoned right now. So, the biggest question is that what to do with this land which is in the heart of the city and the cost of that land would be few thousands of crores of rupees. So, this is where the geotechnical engineering is involved. So, what type of solutions you are going to give to the society related to these activities? Now, coming back to the dredging aspect, the challenge is that dredging is nothing but taking out something from somewhere. So, if you want to deepen rivers what do you do? You remove the sand you might have seen sand being dredged from Dharmatar, Kreek or some other rivers in your localities. At a bigger level this activity is done in the sea. Why? It could be maintenance dredging where you want to maintain every year you have to clean the channels. So, that the ships can come up to the port. Otherwise, think of a situation where the entire sanitation takes place and no ship can enter your port then your country's economy is going to get affected. It is a big issue. So, next time when you go to Elephanta Caves, just look at your left hand side where the JNPT is, JNPT is developed in the Ruport Trust. So, they spend huge amount of money just for maintaining their channels. The way you maintain your channels, see page channels in your houses every day you clean it. Why? So, logic is same otherwise too much of sanitation will take place and water will not drain out. So, there the effect is if sanitation takes place ships cannot come inside the port and economy gets hampered. The second is intentional dredging. Intentional dredging is nothing but sort of a creating something out of the material which you are dredging from the sea, reclamation. So, this is where the geotechnics of dredging comes into the picture. A very interesting topic on which nowadays some people are working is beach nourishment. So, overnight you can create beaches. You have not heard this earlier? That is right. World islands and palm islands, these are good examples of the dredging process. So, you dredge the sand from the sea and then create islands and what is the cost of these islands? So, anyway so this is becoming a very good subject in geotechnical engineering where some of you may concentrate later on. My idea is to give you as much as information possible and whatever I know a bit. So, then comes minerals, mineral extraction process. So, you do waste rocks which are nothing but mill tillings. So, mill you know what is the milling process? Milling process is nothing but an extraction of metals from the ores and whatever is the residue has to be disposed of and piled up. So, this becomes a good case of mill tillings. Sometimes they call it as tilles also, TILLS, tilles, coal refuse. So, one project which I did I would like to show you how we tackle this type of situation at Corba, the washery rejects. What are washery rejects? This is the washing of coal. So, there is a big project going on at most of the coal mines where whatever coal comes out has to be clean, washed, segregated and then only it can be sent for a proper use. So, the biggest challenge is how to use these waste or the rejects which are coming out of the milling process of coal for some important purpose, phospho gypsum. I have talked about this under the category of the sulphates. You know all acids can be nullified when you treat them with calcium carbonate, but then whatever is the residue is calcium sulphate and calcium sulphate where you are going to dispose and how you are going to dispose is a big challenge. So, this is where phospho gypsum becomes important when you process sulphuric acid, phosphoric acid, phosphorous and so on. Agriculture itself is an industry nowadays. So, animal manure becomes non-hazardous waste crops, different type of crops and the stalks of the trees particularly and the wood. Some other categories are organic and liquid waste, solid waste combustion residues, incineration process whenever you adopt whatever is left over again requires some special treatment or a special attention of people how to dispose it off. Reclaim plastic, why there is a ban on reclamation there is a recycling of plastic that is a different issue altogether. Why recycling of plastic is banned? Yes please that is right that is correct sulphur trioxide. So, whenever you incinerate plastic or recycle plastic basically it is a PVC chain polyvinylchloride chain. So, when you break it you require lot of energy. So, the first question is from where you are going to bring so much energy whether it is economical or not and second issue is when you are breaking these bonds lot of sulphur trioxide goes into the environment and the waste glass. Waste glass also is attaining lot of attention of people particularly from geotechnical engineering fraternity. I give you an example of beach nourishment. Sometimes they call it as beach recreation also you may recreate beaches you know wherever sands are less. It is a good example is our society is producing lot of waste glass most of the drinks juices you know utility items they are contained in glass. So, the question is once you have used it you simply throw it. Now, if you crush this glass it becomes sand and that sand can be used for nourishment of beaches and recreation of beaches. I will give you one example where this type of work has been done. So, this is again interesting process one of you should adopt this as a you know business. We need more entrepreneurs in our subject now lot of work is required to be done in this areas you can do very well in life.