Bhagirathpura Tragedy and its Lessons

 The line between the private and the public in India is demarcated by garbage and sewage. People are particular about keeping their houses spic and span but are not bothered about public spaces, particularly the roads bordering their houses. Consequently, these roads are littered with garbage and sewage with the expectation being that this waste will be taken care of by urban local bodies ULB). However, the cleaning of garbage and the transportation of sewage and its treatment to prescribed standards is a very expensive proposition requiring the levy of taxes and charges for the same from the citizens. This does not happen as not only are the charges levied much less than what they should be but also even these low charges are not levied on a regular basis. Thus, our cities and towns are mostly dirty and strewn with garbage and with open drains flowing with foul smelling water. Some amount of solid garbage collection does take place but the waste water flows untreated and contaminates both the ground water and water bodies, especially rivers and streams that flow through these cities.

Ideally, the waste water should be conveyed through sewers to sewage treatment plants (STP) and then properly treated there before being released into the environment. However, laying of sewer lines and construction and running of STPs cost a lot of money which is not available with the ULBs. Even where sewers have been laid in some of the bigger cities, they are not functioning properly because the flow in these sewers is not enough to transport the sewage to the STPs and so deposition of sludge takes place in the sewers blocking them. This corrodes the sewers and cracks develop in them leading to the leakage of highly toxic sewage water into the ground near these cracks. Simultaneously, there are the potable water pipelines near these sewer lines and they too in many cases have cracks in them as they were laid quite some time back. So, in many cases the water from the sewers contaminates the water in the potable water pipelines.

Sometimes, the cracks in the sewers and in the potable water pipelines are so great that the amount of contamination becomes large leading to fatal outcomes for the citizens. The recent horrid example of this is the diarrhoeal outbreak in the Bhagirathpura locality in Indore where more than twenty people have died and hundreds have been hospitalised. The irony is that the city of Indore is the cleanest city of India and yet this has happened there. The reality is that Indore is clean only as far as solid garbage removal is concerned but it has not been able to collect and treat its waste water properly and so this tragedy has happened there. Indore is clean on the surface because it has a fairly good collection and treatment system for the solid garbage that emanates from the houses. This is because upwards of ₹ 1000 crores are expended annually for doing this which is paid for by the state government as the Indore Municipal Corporation recovers only about 10% of this cost from user charges. Properly collecting and treating the waste water would cost another ₹1000 crores or more which the state government is not willing to subsidise. So, even though there are sewers and STPs in place to collect and treat the waste water, this is not being done because of a lack of funds for doing so.

The way out of this impasse is to move away from centralised sewer and STP based systems of waste water collection to localised systems at the household and community level, which treat both waste water and garbage as reusable resources and not something to be thrown away. This will happen only when the mindset of people which is that of releasing waste water and garbage into the public spaces is changed. In fact the centralised garbage collection system too does not work very well in most places because of its high cost and is working in Indore only because it is being heavily subsidised by the state government. Thus, what is needed is household and community level waste collection, treatment and reuse systems as shown in the graphic below. Indeed, this system incorporates a rainwater harvesting system also to cover the potable water supply requirements also. This will be possible only with extensive awareness building drives among the citizens so that they take the responsibility instead of putting it on the shoulders of the cash starved ULBs.  

This circular system relies on the segregation of grey water from the bathroom and kitchen from the black water from the toilets and is very cost effective because treatment of grey water is much easier than that of black water. The details of this system are as given below.

1. The rainwater falling on the roof of the building is either harvested or recharged. Harvesting is more costly as it involves the construction of an underground sump to collect the water. Currently the cost is about Rs 8 per litre as a reinforced concrete tank has to be constructed. Thus, an optimisation has to be done as to how much of the rainfall is to be harvested and how much recharged depending on the groundwater yield in a particular area, which in turn depends on the underlying hydro-geological characteristics, as recharging is much cheaper. In hard rock areas with poor water availability in summer, water harvesting can be done to take care of the water demand in the summer months if the groundwater dries up then. However, if there is water recharging done on a mass scale throughout the urban area both in a decentralised and a centralised manner, then most towns in the country will have adequate water in the confined aquifer. In alluvial plains, like in the Mahanadi, Ganga and Godavari basins of Chhattisgarh, even the shallow aquifer will have adequate water in summer if water recharging is done. That is why in the diagram two options have been provided and there is also a recharge pit alongside the harvesting sump. This pit is filled with a mixture of gravel and sand and is designed to be of a size to absorb the flow of rainwater coming to it from the roof. The rainwater falling on the ground too will be recharged either directly through the soil if there is a garden or the water falling on the paved area will be directed to the recharge pit. The rain water falling on the roof is filtered through a mixture of gravel and sand before being collected in the harvesting sump. The first one or two showers are bypassed to the recharge pit as the water is dirty with dust gathered on the roof and so about 80 percent of the rainfall can be collected if so required but usually to optimise on storage construction costs, less is collected.

2. The harvested rainwater and the groundwater provide the potable water supply for drinking, washing and bathing uses. There is separate plumbing under a dual plumbing system for the water for flushing of toilets and gardening, which is to be supplied from treated grey used water.

3. The grey water from the bathroom and that from the kitchen, which latter has to first pass through an oil and grit trap, are directed to a filtration tank consisting of gravel, sand and charcoal. After filtration the water is collected in a sump where it is aerated and chlorinated to clean it further. This water is then used for flushing of toilets and gardening through a separate plumbing system. In this way the use of potable water for these uses is obviated which is a considerable saving because as per the CPHEEO norms, of the 135 lpcd of water supply as much as 25 lpcd is for gardening and 40 lpcd for flushing of toilets and only 70 lpcd is for potable uses. Since the black water does not have to be carried in sewers, the quantity of water needed for flushing is greatly reduced and special toilets can be installed that require less water. Sensors have to be placed in the sump and the overhead tank to automatically regulate the pumping of water from the former to the latter so as to prevent over flow in the former.

4. The black water from the toilets and the green waste from the kitchen are sent to a biogas plant. The gas generated from this plant contains mainly methane and some hydrogen sulphide also. The latter being harmful, has to be removed through a scrubber. The gas generated can be used for cooking and for heating water in a gas geyser. In case of four storied or higher buildings, the gas produced can be used to generate electricity which can be reused in the operation of the aerators for grey and black water treatment. The digested slurry is collected in a two chambered sump in which one chamber is alternatively filled up and the sludge further digested by anaerobic decomposition to be turned into manure that can be used in the garden while the other chamber fills up much like a two-pit latrine but with the water not leaching into the ground but drying up slowly in the chamber that has filled up as an aerator runs in it to both oxidise the slurry and dry it up. The energy required for this is much less than that needed to run the heavy blowers in large sized STPs of centralised systems. In fact, if the pits are built large enough then even aerators can be dispensed with as the retention time increases allowing for natural drying up of the sludge.