Two pollution watchdogs, same STPs, very different readings, Pg4.

Key Highlights:

• CPCB inspection in June revealed all 37 DJB-run STPs in Delhi failed to meet prescribed discharge standards.
• DPCC monitoring reports from the same month contradict CPCB, rating most plants as "meeting standards".
• 36 plants failed to match Fecal Coliform permissible limits, with numbers as high as 4.7x10⁹ MPN/100 ml recorded against the limit of 230 MPN/100 ml.
• CPCB recorded high levels of Ammoniacal Nitrogen, indicating incomplete biological treatment, at multiple facilities.

Detailed Insights:

• CPCB data indicates several plants discharged water with BOD and COD above permissible limits, signifying untreated organic matter.
• Discrepancies exist between DPCC and CPCB reports for key facilities like Akshardham, Najafgarh, and Okhla Phase VI STPs.
• A DJB official cited differences in the number of parameters tested by DPCC and CPCB as a reason for the variation in results.
• DJB's own laboratories have lost NABL accreditation, making independent verification of DPCC's results unreliable.
• CPCB officials highlighted that this was the first time the Board carried out an independent assessment of all DJB plants in Delhi.
• The performance of STPs can fluctuate depending on inflow and load, but large differences in compliance reports are a cause for concern.

Key Concepts Involved:

• STP (Sewage Treatment Plant): Facility designed to remove pollutants from wastewater.
• BOD (Biochemical Oxygen Demand): Amount of oxygen required by microorganisms to decompose organic matter in water.
• COD (Chemical Oxygen Demand): Measure of the total amount of oxygen required to oxidize all organic compounds in water.
• Fecal Coliform: Bacteria found in human and animal waste, used as an indicator of water contamination.