BMC faces major sludge management challenge as sewage plants upgrade across Mumbai

Sewage treatment plant in Colaba. File pic/Shadab Khan

The BMC is grappling with a major challenge: managing the massive amounts of sludge that will be generated by the city's upgraded sewage treatment plants. The civic body has begun upgrading all eight sewage treatment plants (STPs) in the city, expected to be completed between 2026 and 2028. Once operational, these plants will treat around 2400 million litres of sewage daily.

Following treatment, approximately 23 to 24 per cent of the volume will result in sludge, posing a significant disposal challenge. It is estimated that about 500 tonnes of sludge will be generated each day. Civic officials said this waste must be scientifically treated to prevent land and soil pollution.

"At the Colaba plant, we will treat 37 million litres of sewage daily. This will generate around nine tonnes of sludge per day, which cannot simply be dumped in the open," said a civic official.

At the Colaba plant, the BMC will treat 37 million litres of sewage daily. Pic/Shadab Khan

The BMC is currently scouting for suitable technology to manage this sludge. "We are exploring viable technologies for the Colaba plant. Ideally, we are looking for a solution that can also generate revenue from sludge treatment. However, if such technology is not available, we will have to spend money on treating it. Even then, we aim to find a cost-effective method," Additional Municipal Commissioner Abhijit Bangar told mid-day.

According to the Central Pollution Control Board (CPCB) 2020 report, untreated sludge dumped in the open can lead to soil and water pollution. However, treated sludge can be repurposed for agriculture or even used in cement kilns or waste-to-energy plants.

The BMC initiated the STP upgradation project in 2022, with an estimated cost of Rs 27,309 crore.

Deadlines

The Bhandup, Ghatkopar, and Versova sewage treatment plants are slated for completion in 2026, while Bandra and Dharavi will be ready in 2027. The Malad sewage treatment plant is expected to be completed by 2028.

2022
Year STP upgradation project began