Chennai:
Water managers in the city should now think about reuse
of waste water rather than focusing on alternative resources, according to an
expert.
Delivering Dr NG Anuthaman memorial endowment lecture on
'Science and Technology for sustainable water supply' at the Alumni Association of College of Engineering in Anna University here,
S Mohan, professor, department of Civil Engineering, IIT Madras, said that of
the total water supplied to residential areas nearly 80 per cent ends up as
sewage water.
“Why not the government treat it and use it rather than
hunt for alternative sources of water which is located hundreds of kilometer away,”
said Mohan.
His comment comes when the water managers are struggling to
provide adequate supply of water to the city as the water supply in the
reservoirs reservoirs have
Citing the example of Singapore and The Netherlands, he
said the thought of using the sewage water after being treated is unpleasant
but then one has to save our water resources.
He also highlighted that the fresh water resources in the
country has come down from 6042 cubic metres during the years 1947-50 to 1548
cubic metres in 2011. “We have less than 1700 cubic metres of water which puts
us in the UN list of water stressed nations,” he added.
He also stressed that the city has to survive on
desdalination plant but in the longer run it is not advisable. “Rather going in
for desalination, the state should look into alternative technologies like
nanotechnology to make desalination cheaper,” he said.
Usually, 2.5 kilowatt per hour of power consumption
results in production of one cubic metre of water which is too costly. Now,
there is lot of research going on nanotechnology membranes to make desalination
plant cheaper, he said.
He also stressed on the need for decentralized waste
water treatment plant in every building to treat the sewage water besides focusing
on local reuse and recycle.
He said besides recycling of waste water, the city should
also look at Orange County model where waste water is injected into the ground
and from where it is treated and supplied to people.
He also expressed concern that the lack of thought
process while laying the sewage lines in the city. The sewage lines are right
above the drinking water lines unlike other countries where the sewage and
drinking water pipes are kept five metre apart horizontally
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