DJB floats water-cleaning organic wetlands over lakes across Capital

New Delhi: The Delhi Jal Board is now setting up floating platforms with plants across the city's lakes in an attempt to clean them of nutrient pollutants and by extension improve the water there. These "floating wetlands" have plants that have roots with bacteria that can separate organic waste from the water in the lakes.

These floating platforms have recently been installed at the Sanjay Van Lake and had also been early placed in lakes at Nangloi and Rajokri but officials working on the "City of Lakes" project of the DJB have said that these floating platforms alone may not be enough to clean the water adequately.

On these floating wetlands, which can cost between Rs 8,000 to Rs 10,000 apiece along with maintenance, pampas grass, spider lily, yellow and red canna, elephant ear plants, and soft rush or bulrush plants. Officials have said that nearly 600 such floating "wetlands" have been installed in the Sanjay Van Lake and over 1,300 have been installed at the Sonia Vihar lake. In addition to this, the wetlands have been installed at the Jaffarpur Kalan Lake, Nangloi lake, and Ranikhera.

Officials have explained that an aeration system also needs to be put in place that will supply the required amount of oxygen to the bacteria in the plants' roots, which in turn helps to clean out ammonia and other pollutants from the lakes thereby reducing the biological demand for oxygen.

Curiously, however, the plants on the floating wetlands contribute to cleaning up just around 10 to 12 per cent of the pollutants themselves with officials saying that the need for the aeration system only increases as the plants grow and mature. Officials said that as the plants grow, their intake of the polluting nutrients is reduced, necessitating the aeration system's use.

Significantly, the aeration systems that complement the floating wetlands are still in the making with officials saying that they are planning to introduce these floating platforms in ten lakes across the city as part of their project. Regardless, the DJB has said it will ensure the maintenance of these sites once the wetland systems are in place. The project by the Delhi Jal Board is intended to revive around 50 water bodies in the city with work on nearly 20 such water bodies nearing completion.

However, given what DJB officials have said about the systems being put in place, it would seem to experts that authorities are not exploring more efficient methods, adding that they should first focus on making sure that no pollutants on drain water enter the lakes in the first place.