A small island made out of solid waste and construction debris is an unexpected sight in the thick blanket of water hyacinths that cover the wetlands stretching behind Kalindi Colony along the Delhi-Noida-Delhi flyway.
Until May last year, this land was a dump for solid waste which was excavated to build the island and an embankment around it, as part of the South Delhi Biodiversity Park — a 200 hectare stretch on the Yamuna floodplains being developed by Delhi University Professor CR Babu in collaboration with Delhi Development Authority (DDA).
“We plan to plant 1 lakh trees in the entire embankment area, so people can walk through a forest. The island will be covered by patches of grass, and connected through canoes, where one can sit and do fishing,” Professor Babu told The Indian Express.
At present, the water that surrounds the island and much of the wetlands — from Dhobi Ghat in Okhla to DND flyway near Kilokari village — is sewage from 25 drains, which would render it difficult for fish to survive.
However, Professor Babu plans to treat an estimated 1,500 million litres per day (MLD) of sewage from these 25 drains through 11 constructed wetland systems which will naturally purify wastewater before it enters the Yamuna — a method he has successfully used in the past to revive the lake at Neela Hauz biodiversity park in South Delhi.
Under the new project, one such constructed wetland system started functioning last week and is treating around 15 MLD of wastewater from Kilokari drain, which used to accumulate behind Kalindi Colony.
“For a very long time, the constructed wetland system has been ignored by civil engineers, who have been keen about sewage treatment plants (STPs). You need a lot of energy to run STPs… The constructed wetland is a viable alternative,” he said.
The wetland model that treats waste from Kilokari drain involves a three-step process. Wastewater from the sewage first enters an oxidation pond, where solid material is trapped in a wire mesh and atmospheric oxygen dissolves in the water. The water is then passed from channels through ridges made out of boulders, which creates turbulence and causes aeration — in other words, it dissolves oxygen in water. In the final stage, species of 25 plants — including typha, phragmites and cyprus — decompose waste in the water further by drawing nutrients from it. The water is then released into the wetlands.
Prof Babu said the remaining 10 constructed wetland systems will be ready by mid next year.
📣 The Indian Express is now on Telegram. Click here to join our channel (@indianexpress) and stay updated with the latest headlines