Overview of Delhi’s Sewage Treatment Challenges

The Delhi government claims that its sewage treatment plants (STPs) are functioning at over 88% capacity, implying efficient wastewater management. However, the Delhi Pollution Control Committee (DPCC) reports discrepancies in water quality from these plants.

Water Quality Deficiencies

• Out of 17 drains carrying treated effluent, 16 exceed permissible pollution levels.
• Key parameters breached include: 
  1. pH
  2. Total Suspended Solids (TSS)
  3. Chemical Oxygen Demand (COD)
  4. Biological Oxygen Demand (BOD)
• High BOD levels threaten aquatic life by depleting dissolved oxygen.

Challenges in Drains and Treatment

• 22 drains feed the Yamuna within Delhi; 10 are fully tapped, and two partially.
• Eight drains remain untapped and require diversion to treatment facilities.

Pollution Causes and Treatment Shortfall

• The primary pollution cause is the discharge of treated, partially treated, and untreated sewage.
• Current treatment shortfall: 88 million gallons per day (MGD), primarily due to unauthorized colonies lacking sewer networks.

Measures to Address Shortfalls

• Upgrade and expansion of eight STPs at various execution stages.
• Development of 40 decentralised treatment units: 
  1. 26 Decentralised Sewage Treatment Plants (DSTPs) across the city
  2. 14 in the Najafgarh drainage zone

Future Plans and Requirements

The Delhi Jal Board (DJB) has initiated a tender for a long-term Sewerage Improvement Scheme 2043, which includes:

• Surveys
• Detailed Project Reports (DPRs)
• Gap analysis
• A citywide sewerage master plan

Senior DJB officials emphasize the need for additional STPs to accommodate increasing sewage due to population growth and urban expansion.