12 of 37 STPs in Delhi didn’t meet standards in Nov: Report

The number of STPs found to be failing on treatment norms has increased with nine such plants earmarked by the DPCC in September and October reports in the september and october reports, nine plants were found to be failing norms

The latest Delhi Pollution Control Committee (DPCC) report shows that, of Delhi’s 37 sewage treatment plants (STPs), 12 did not meet the treatment standards prescribed by the Central Pollution Control Board (CPCB) in Novemberwhile sample could not be lifted from the 13th facility at Sonia Vihar, even as the clean-up of Yamuna is under the spotlight.

The latest report throws spotlight on Yamuna pollution. (Sunil Ghosh/HT Photo)

The report, dated December 17, is part of the monthly assessment report for November, and it reveals that a large section of the STPs do not meet the prescribed norms set for parameters such as faecal coliform, biological oxygen demand (BOD), Chemical Oxygen Demand (COD) and total suspended solids (TSS), among others. DPCC collects and analyses samples for STPs once every month.

The faecal coliform level was 234 times the prescribed limit at Molarband STP, 73 times more than the limits at Ghitorni treatment plant, 70 times at Vasant Kunj(2) STP, while other plants also failed to meet other parameters. Importantly, the number of STPs found to be failing on treatment norms has increased with nine such plants earmarked by the DPCC in September and October reports.

DPCC report said that the 12 STPs which failed to meet the standards include Sen Nursing home STP, Delhi gate, Kapashera, Molar Band, Okhla (old), Mehrauli, Vasant Kunj 1 and 2, Ghitorni, Yamuna Vihar phase 1 and phase 3 and Nilothi New (Phase-1). While most STPs failed to meet the faecal coliform treatment levels, the ones at Mehrauli, Vasant Kunj, Yamuna Vihar and Mehrauli failed on three or more parameters. Meawhile, no sample could be taken from the Sonia Vihar STP as there was no flow during the inspection.

Against the prescribed limit of 230 MPN/100ml, the faecal coliform level at outlet of Molarband was found to be 54,000 units; 3,500 units at Mehrauli and 16,000 units at Vasant Kunj-2, and 9,200 units at Vasant Kunj-1. The TSS and BOD levels should be less than 10mg/L, according to the CPCB parameters, but six STPs failed to meet these standards.

STPs are the primary tools its attempt to clean Yamuna in the city which has an estimated sewage generation of 3,600 MLD (million litre per day) or 792 MGD (million gallons per day). Delhi estimates that the 80% of its water supply (990 MGD) comes back as wastewater. Delhi has 37 STPs at 20 locations which have an installed capacity to treat only 667 MGD water. Delhi economic survey underlines that the city’s capacity utilisation is only 565 MGD and the gap in sewage treatment is 227 MGD which ends up in drains, waterbodies and Yamuna. Experts have pointed out that this estimated sewage generation does not take into account the groundwater being used by the people.

Even the 565 MGD (million gallons per day) waste water, which gets treated before being released in the river, suffers from underperforming Sewage Treatment Plants.

As per the CPCB norms, the Total Suspended Solids (TSS) in the water coming out of the STP should be 10 mg/l or less. Similarly, the standard for BOD levels — the amount of oxygen required by aquatic life to survive — is also 10 mg/L. The DPCC found that the TSS levels at outlets were four to 3.5 times higher--36mg/L at Yamuna Vihar phase-1, 27mg/L at Yamuna Vihar phase-3, and 24 mg/L at Vasant Kunj-2 The biochemical oxygen levels were also two to three times higher at several plants .

Delhi’s STPs are repeat offenders. Bhim Singh Rawat, a Yamuna activist and member of the South Asia Network on Dams, Rivers and People (SANDRP), said that the DJB estimates sewage generation without taking into account the ground water being extracted by people. “The real quantum of sewage is much more, the STPs are inadequate and underperforming and even the water that gets treated does not meet norms,” he said, adding that the government should focus on improving STP management, restoring ecological flow and protecting floodplains.

“From years, we have been hearing about STPs not meeting norms but no accountability is fixed. There is no monitoring mechanism which involves the civil society and violations continue every month without any repercussions.”