IIT-B’s N-Treat tech to help BMC treat sewage in nullahs on-spot

IIT-B’s N-Treat technology uses a seven-stage process to treat sewage in nullahs with the help of screens, gates, silt traps, curtains of coconut fibres for filtration, and disinfection using sodium hypochlorite, without the requirement of additional space.

The project is a temporary and short-term measure to comply with the National Green Tribunal (NGT) that directed the civic body in 2019 to permanently check the flow of sewage from nullahs and their tributaries into the sea and creeks in Mumbai. In March this year, BMC sought a consultant to prepare a detailed project report (DPR) to check the discharge of sewage from major nullahs and their tributaries and find permanent solutions for preventing such pollution. A senior civic official said, “Multiple civic departments are working on the issue. While a permanent solution is being prepared to check sewage discharge into the nullahs and subsequently into the sea, we are working to handle the present pollution in the nullahs.”

The project is estimated to cost BMC Rs 82 crore, and will be taken up in stages over the next five years. The official quoted above said, “BMC approached IIT-B for a solution for the treatment of sewage in nullahs. IIT submitted a detailed proposal with the use of N-Treat technology. This is the first time it is being used by the civic body. Tenders have been floated to appoint a contractor for the project.”

Storm water drains (SWDs), or popularly called nullahs, are meant to discharge rainwater into the sea. However, BMC conducted a survey four years ago that found that over 75,000 properties and shanties along the banks of these SWDs discharge untreated sewage into the canals.

Of the 25 nullahs selected for the project, five are in Bandra and Santacruz area – Rahul Nagar nullah, Boran nullah, Behrampada nullah, and P&T nullah in Santacruz and on Link Road; seven are in Andheri – Milan Subway nullah, Cargo Complex nullah 1 and 2, Koldongri nullah, Abhishek nullah, Malpadongri nullah, and Mogra nullah; six are around Malad and Goregaon – Dnyaneshwar Nagar nullah, Krishna Nagar nullah, Chincholi nullah, Piramal nullah, MHB Malad nullah, and Paptarshi nullah; and the remaining are north of Kandivali – Janupada, Pancholi, Kumbharkala, Kora Kendra, Tawdem Tare Compound, and Avdut nullahs.

Stalin Dayanand, from NGO Vanashakti which approached NGT in 2017 for coastal pollution due to discharge of untreated sewage into the sea, said, “What BMC is doing is the bare minimum. It is not enough but it is a start. The civic body is doing today what was told to it in 2018. Moreover, all its activities and projects are designed to look expensive, whereas simple measures are enough to achieve the same effect.”

Ashok Mengde, Chief Engineer of the Mumbai Sewage Disposal Project department which has undertaken this project, said, “The project has been undertaken and tenders have been floated… Overall, this matter is sub-judice.” [In 2020, NGT fined BMC Rs 34 crore for non-compliance. The civic body challenged the fine in the Supreme Court].