The Hindu 11.07.2016
TNAU college raises ‘kal vazhai’ farm for treatment of wastewater
Agriculture college develops two-stage organic treatment of sewage
NATURAL CLEANING:The open well at the farm of the TNAU - Agricultural
Engineering College and Research Institute at Kumulur near Tiruchi where
the treated water is stored.— PHOTO: M. SRINATH
Every drop of sewage water collected from the girls’
hostel of the Tamil Nadu Agricultural University – Engineering College
and Research Institute at Kumulur near here is being treated and let off
into an open well of the institute for irrigation for paddy, maize, and
horticultural crops.
The availability of sprawling
area on the campus has facilitated the purification process. The
wastewater, which contains heavy metals, is purified in two phases. A
channel has been dug for about 10 metres and the black wastewater is
first passed through a thickly grown reed bed. Outside the bed, the
colour of the raw sewage changes, indicating its partial purification.
The semi-treated water then is let into the thickly cultivated
kal vazhai
(cana indica) plants. “It may be hard for you to believe that the sewage water becomes pure beyond the
kal vazhai
bed,” says K. Ramaswamy, Dean of the Institute.
He explained that the reed and
kal vazhai
acted as a natural agent for purification of the sewage water. The
sewage water from the hostel contains a large number of organic
impurities, which are first purified by the reed plants. The
kal vazhai
absorbs heavy metals such as aluminium, iron, and phosphorous and their compounds and grows on them.
“The
water is purified and sent to an open well about 500 metres away from
the hostel. We have buried PVC pipes below the earth,” says V.
Ravikumar, Professor and Head of the Soil and Water Conservation
Engineering Department of the institute.
The
institute has been using the water for irrigating the fields. “The well
whose water level was low about a year ago, has registered a sharp
improvement, thanks to the continued discharge of the treated water
round the clock,” he said.
The daily realisation of
purified water is about 10,000 litres, according to an estimate. The
well is overflowing now, in contrast to last when it the water level was
10 to 15 feet.
The institute has developed a separate farm all around the well for treatment of the sewage water.
