Delhi will treat all sewage it generates as per prescribed standards by Dec

Delhi will be able to treat all the sewage it generates as per the prescribed standards by December which will help reduce the pollution load on the Yamuna river, Water Minister Saurabh Bharadwaj said on Friday.

Addressing a press conference, he said the sewage treatment plants (STPs) in the national capital will be able to treat around 814 million gallons of wastewater per day (MGD) as per the prescribed standards by December.

Delhi generates 768 million gallons a day (MGD) of sewage. The 35 STPs in the city have a cumulative treatment capacity of 632 MGD.

At present, these STPs are utilising only 69 per cent of their installed capacity. This means only 530 MGD of the 768 MGD sewage is being treated.

Only 160.5 MGD of the treated wastewater meets the prescribed standards according to which biological oxygen demand (BOD) and total soluble solids (TSS) in treated wastewater should be less than 10 milligrams per litre.

BOD, an important parameter for assessing water quality, is the amount of oxygen required by aerobic microorganisms to decompose organic material present in a water body. A BOD level of less than 3 milligrams per litre is considered good.

Officials said that Delhi's sewage treatment capacity will increase to 727 MGD by June and 814 MGD by December this year.

The treatment capacity will be further increased to 965 MGD by June next year to accommodate the future increase in sewage generation, they said.

Bharadwaj also said that the sewer network has been extended to 839 of the 1,799 unauthorised colonies in Delhi.

The 22-kilometre stretch of the Yamuna between Wazirabad and Okhla in Delhi, which is less than 2 per cent of the river's length, accounts for around 80 per cent of its pollution load.

Untapped wastewater from unauthorised colonies and jhuggi-jhopri clusters, and poor quality of treated wastewater discharged from sewage treatment plants and common effluent treatment plants (CETPs) are the main reasons behind high levels of pollution in the river.

The Delhi government has promised to clean the Yamuna to bathing standards by February 2025.

The river can be considered fit for bathing if BOD is less than 3 milligrams per litre and dissolved oxygen is greater than 5 milligrams per litre.