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The Delhi government on Wednesday cleared projects planned at a cost of ₹ 570 crore for abatement of pollution in the Yamuna with a focus on developing decentralised sewage treatment plants (DSTPs) in rural and unauthorised areas of the city that are currently not covered by the sewage network.

These projects include the construction of DSTPs in several areas of the Bawana and Mundka belt along with the laying of sewer lines in the unauthorised colonies/rural areas of the outer Delhi region.

Deputy chief minister Manish Sisodia, who is also the Delhi Jal Board (DJB) chairman, said the water utility is working in a phased manner to upgrade the sewage system of the capital to ensure that no untreated effluents are released into the Yamuna. “We have decided to set up DSTPs in unauthorised colonies and residential areas. While it is not easy to lay pipelines all over the place for large STPs, it is possible to construct low capacity DSTPs at a low cost. The construction will use space sparingly and these plants will be aesthetically good,” he added.

Also read: Over 10,000 evacuated as Yamuna flows above danger mark

Under the projects approved on Wednesday, the water utility will carry out construction of DSTPs, with a cumulative capacity of 26MLD (million litres per day), and waste water pumping stations in colonies such as Nizampur, Ghevra, Kanjhawala, and Mohammadpur Manjri under Mundka assembly constituency.

The DJB will spend ₹ 427.6 crore on constructing DSTPs and laying sewer lines in these rural areas, while ₹ 132.6 crore will be spent on similar facilities and sewage network in nine villages and 24 unauthorised colonies in Bawana region.

Currently, the untreated sewage from these areas is released into the Yamuna.

These plants will be run on IFAS technology (integrated fixed film activated sludge) which involves adding an attached growth media to an activated sludge tank to facilitate biomass growth and strengthen the treatment process, the DJB official explained.

DSTPs and sewage in Delhi

According to the 2022 economic survey, Delhi has an installed capacity to treat around 597MGD (million gallons per day) of sewage. The government has said STPs with a total capacity of 239MGD will be added to the sewage treatment infrastructure by June 2023.

The Sewage Treatment Augmentation Action Plan for 2041 proposes 56 DSTPs with a cumulative capacity of 95MGD while another 240MGD capacity is expected to be added via such decentralised units in land pooling areas.

A senior DJB official working on the project said DSTPs lead to major cost savings. “In some cases, the cost savings related to transportation infrastructure for effluents is around 80%. Moreover, since the water in these DSTPs is treated near the source, the treated wastewater can be used locally for horticulture purposes, irrigation and rejuvenation of water bodies,” the official said, asking not to be named.

The water utility has been pushing for DSTPs since 2019 at least, but non-availability of land was hindering the projects.

A DJB official said currently, the board has a proposal to construct 41 such treatment units but land is available only at 28 sites. “We are pursuing land owning agencies such as the Delhi development Authority and the revenue department for land at the other sites,” the official said.

Also read: Green tribunal asks PWD to rethink elevated road on Yamuna floodplain

According to current projections by DJB, the first lot of DSTPs will be made operational by December 2023. “For the rest, we will need at least 15 months from the date of allocation of land,” the official added.

Diwan Singh, environmental activist who organised the Yamuna Satyagrah for rejuvenating the river and other water bodies in the city, said the DJB should first focus on the existing STPs not meeting the pollution parameters. “Moreover, in a city like Delhi, space is a major constraint. DJB may not be able to find space for DSTPs in highly dense populated areas. In such cases, a centralised system may function better,” he said.

The Delhi government has set a deadline of cleaning the Yamuna by February 2025. On November 18, 2021, chief minister Arvind Kejriwal announced a six-point action plan for cleaning the river -- another in a long series of such plans announced by successive governments since 1993, to clean the much polluted river. But filthy flows the Yamuna still.

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