NEERI finds solution to unclog city drains

Mumbai: As the sewage menace that is plaguing Mumbai’s rivers shows no sign of abating, the National Environmental Engineering Research Institute (NEERI) has come up with a system ensuring the in-situ (in the original place) cleaning treatment of storm-water drains or nullahs. Known as Renue (Restoration of Nullah with Ecological Units), the treatment uses natural process like phyto-traps, solar aeration and wetland plants for cleaning drains. The institute has recently demonstrated it in Nagpur and Amritsar and are in talks with the Ulhasnagar Municipal Corporation to demonstrate in the drains in the city.

The Renue project involves treatment of sewage in the running flow without disturbing the shape of drains and by employing natural processes like phytoremediation, that is treatment using anti-pollutant plants, microbial consortia as well as physical and biological operations to degrade sewage. “We have focused on reducing sewage in drains using natural ways, which is why we are not even altering the existing shape and landscape of the drains. No chemical is required in the treatment,” said Dr Ritesh Vijay, principal scientist, Centre for Strategic Urban Management, NEERI.

The project also boasts of advantages such as no extra civil construction, reduction in pollution, minimum operation and maintenance, electricity free treatment, odour control and reduction of flies and mosquitoes.

The treatment includes screen and grit trap, which traps solid waste flowing in the drains, followed by sedimentation, which helps in settling down the waste water by providing sufficient space. The phytotrap and biomat that consists of lightweight material, which attaches bacterial growth, and trap suspended organic matter, thereby filtering sewage water. The solar diffused aerator helps in increasing the concentration of dissolved oxygen in the drain water and wetland plants helps in preventing growth of unwanted plants and algae.

“We have the problem of polluted rivers in Mumbai as well. We hope to get help from the BMC and state government to revive the city’s rivers,” said Rakesh Kumar, director, NEERI.