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On the reuse of nutrients and water

April 27, 2013

The city is faced with a massive challenge when it comes to treating wastewater. Of the 1000 million litres per day of wastewater generated only about 430 million litres gets treated every day. Stormwater drains are thus full of sewage and this ends up in our rivers, lakes and groundwater.

Under a new set of projects additional waste-water treatment plants are being put up yet they may prove to be inadequate. On the other hand when one looks at smaller wastewater systems the city has more than 2000 of them according to Dr Anant Kodavasan, a member of an expert committee looking into the issue. Many of them are however are either dysfunctional or are performing below par. The installed capacity of these systems are close to 200 million litres per day, a significant volume.

The best bet is for all the apartments and institutions that have these plants to get them evaluated and brought into efficient performance levels. The cost of the treated waste-water ready for use as non-potable water could vary between Rs 18 to Rs 30 a kilo-litre , significantly less than the water being purchased from private water tankers.

The State Pollution Control Board insists on every apartment or layout which has more than 80 flats to have its own waste-water treatment plant. If these plants are located well , not hidden in basements, they consume less energy , treat water well and produce quality good enough to be used for flushing toilets and for the landscape. A systematic re-evaluation of these plants is therefore necessary to fit them into the overall strategy of managing waste-water in the city.

The other advantage with these systems such as the one in the Jayadeva Institute of Cardiology, a hospital in the southern part of the city , is that they produce not only treated wastewater for reuse but also other byproducts such as biogas for cooking and bio-sludge manure for gardening. As Dr Ravishankar the designer of the system explains ‘ these plants not only look well, there is no odour and there is no waste. All byproducts are reused and the system pays back for itself in 4 to 4 and a half years.”

With some treatment plants there is an excess of waste-water available on site. A system of sharing between apartments has to evolve and a market for its distribution created. ITC –Windsor Manor for example is able to give its treated wastewater to the golf club opposite since it has more than its requirement. These markets need to evolve further and should be facilitated by the BWSSB and the Karnataka State Pollution Control Board.

Apartment owners, layout residents and institutions are doing the right ecological and economic thing by installing these WWTP’s for not only do they save money they ensure that the environment is not polluted. Investing in R and D , developing better models for operations and maintenance and better consumer education will go a long way in ensuring better water management for the city.

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