Every layout must have a sewage treatment plant
|Nitrate contamination through sewage is the single largest polluter of groundwater in Bangalore|
What scientific age?: Uncollected and untreated sewage ends up in our lakes and rivers and also in our groundwater
Many cities in India can be smelt before they can be seen, if you arrive by train or bus. The overwhelming presence of untreated sewage flowing in stormwater drains or in gutters and collecting pools in surface water bodies is not only un-aesthetic but unhealthy too. This uncollected and untreated sewage ends up in our lakes and rivers and also in our groundwater. Nitrate contamination through sewage is the single largest polluter of groundwater in Bangalore. It is also good to remember that uncollected and untreated domestic sewage is the largest volume of pollutant in a city. The numbers reach over 400 million litres per day in Bangalore.
What should be done?
Cities must invest in a 100 per cent collection and treatment of wastewater. Decentralised systems are emerging that can do so at smaller neighbourhood levels. These decentralised sewage treatment plants can be linked to the nearest park or tank and the tertiary treated sewage used to fill the tanks after a small wetland-based biological process. These will not only keep our tanks full but also replenish groundwater in the surrounding areas.
Layouts of even 200 households can set up treatment plants for waste water and reuse it for non-potable purpose within the layout. Individual apartments are already demonstrating that this is possible and even individual households can treat grey water and black water separately for reuse. A household-centred wastewater treatment approach is what cities of the future are looking at.
In Bangalore, an abysmal Rs. 15 is paid as sewage cess by a household consuming up to 25,000 litres every month. This works out to 50 paise a day. Even beggars are known to have rejected such a sum. How can an institution ever hope to maintain a system and improve infrastructure for collection and treatment of sewage? A realistic hike in price is a must for the city to manage wastewater. The “polluter pays” principle must apply to households as well.
Typically cities tend to invest in fresh water supply systems which tend to bring more water to the city. This fresh water is consumed, turns to wastewater and then, because the collection and treatment mechanism is not in place, becomes a pollutant. The fresh water available in the city as surface water and groundwater now gets polluted, demanding more fresh water from even more distant sources. A paradigm called “fouling the nest.”
An open well can deliver the cheapest water and the most energy-efficient water provided the aquifer is kept full and not allowed to be contaminated by sewage.
Bangalore has set up some excellent wastewater treatment plants at Cubbon Park and Lalbagh. These are state-of-the art units which need to be replicated quickly and in more number of places. There is another excellent wastewater treatment plant in Madivala tank in South Bangalore, which enables treated water to be used to keep the tank full. These need to be rolled out for all tanks.
Only in collecting and treating wastewater and linking it with the protection of our surface and groundwater resources will we ensure sustainable waters for our cities. In this approach lies water wisdom.