NEW DELHI: Nearly eight sewage treatment plants (STPs) failed the prescribed discharge standards for total suspended solids, biochemical oxygen demand and faecal coliform levels in July, the latest report from the Delhi Pollution Control Committee (DPCC) has revealed.
Testing standards across more than 30 sewage treatment plants (STPs) in the national capital, the report provides data for samples collected from both inlet and outlet points.
Flagging the Yamuna Vihar Ph-III treatment plant for non-compliance, the report said the outlet sample from the facility exceeded the set limits for total suspended solids (TSS), biological oxygen demand (BOD) and faecal coliform.
According to the report, the treated discharge from the plant recorded TSS at 32 mg/l against the prescribed limit of 10 mg/l and BOD at 20.4 mg/l against the permissible level of 10 mg/l.
The faecal coliform count at the facility was 7,600 MPN/100 ml, significantly above the prescribed standard of 230 MPN/100 ml, it mentioned.
The most probable number (MPN) is a statistical unit and method used in microbiology to estimate the concentration of viable microorganisms in a liquid sample.
Meanwhile, the sample collected from the STP at Yamuna Vihar showed a faecal coliform level of 1,500 MPN/100 ml, along with high TSS and BOD.The other STPs that have not met the prescribed limits included those at Mehrauli, Ghitorni, two in Vasant Kunj, Keshopur and Kapashera.
The STPs at Mehrauli and Ghitorni showed extremely high levels of faecal coliform, reaching up to 17,000 MPN/100 ml and 18,000 MPN/100 ml, respectively. One of the STPs at Vasant Kunj showed a faecal coliform level of 15,000 MPN/100 ml and the other 9,200 MPN/ 100 ml.
The periodic monitoring of STPs in Delhi is conducted by DPCC to assess the efficiency of sewage treatment and ensure compliance with environmental norms aimed at reducing pollution in the Yamuna river and other water bodies.