The Hindu 11.07.2016
TNAU college raises ‘kal vazhai’ farm for treatment of wastewater
Agriculture college develops two-stage organic treatment of sewage
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.