Water discharged by STPs falls short of norms, Pg7

Key Highlights:

• DPCC analysis reveals that water discharged from Delhi's STPs fails to meet national quality norms.
• 16 out of 17 drains carrying treated effluent showed pollutant levels exceeding permissible limits.
• Key parameters breached include pH, TSS, COD, and BOD.
• BOD levels reached 145 mg/l in Sahibabad drain, 110 mg/l in Shahdara, and 60 mg/l in Najafgarh.
• Treatment shortfall is estimated at 88 MGD due to unauthorized colonies lacking sewer networks.
• DJB is undertaking measures like rehabilitating, upgrading, and constructing STPs to address the issue.

Detailed Insights:

• The Delhi Pollution Control Committee (DPCC) found that treated wastewater in Delhi's drains exceeds permissible pollutant levels, indicating inadequate sewage treatment.
• High BOD levels signify organic waste, depleting dissolved oxygen and threatening aquatic life in the Yamuna.
• The Interceptor Sewer Project partially addresses the issue in Najafgarh and Shahdara drains, which carry approximately 800 MGD of sewage.
• Untapped drains contribute to pollution along the 22-km stretch of the Yamuna between Wazirabad barrage and Asgharpur village.
• The Delhi Jal Board (DJB) is implementing a Sewerage Improvement Scheme 2043 for long-term solutions, including surveys and a citywide sewerage master plan.
• Future plans include additional STPs to manage increasing sewage due to population growth and urban expansion.

Key Concepts Involved:

• Sewage Treatment Plant (STP): Facility designed to remove pollutants from domestic and industrial wastewater.
• Biochemical Oxygen Demand (BOD): Amount of dissolved oxygen needed by microorganisms to decompose organic material in water.
• Chemical Oxygen Demand (COD): Measure of the amount of oxygen required to oxidize both organic and inorganic compounds in water.
• Delhi Jal Board (DJB): The agency responsible for water supply and sewage management in Delhi.