The Nemmeli Desalination Plant: Providing Clean Water to One Million Residents.

WABAG constructed and operates a Reverse Osmosis (RO) based seawater desalination plant in Nemmeli to address Chennai’s water shortage issues. Initially designed to produce 100,000 m³/day of potable water, the plant was expanded to 110,000 m³/day in 2017 to accommodate rising Total Suspended Solids (TSS) levels due to climate change. The facility, built on a 9.32-hectare site 45 km south of Chennai, supplies fresh drinking water to one million residents in the southern suburbs.

Project Highlights:

• Scope: Design, build, and operate (DBO) contract with initial capacity of 100,000 m³/day, expanded to 110,000 m³/day in 2017.
• Technologies: Single-pass SWRO with pre-treatment by Flocculation, Clarification, Disc Filter (DF), and Ultrafiltration (UF).
• Impact: Provides a reliable water supply to combat the severe water shortage in Chennai, supporting a growing population of over 9 million.
• Features:
  • Feed Water: Sea water with TDS of 41,900 mg/l and temperatures between 24 to 32 °C.
  • Intake System: 1,050 m long HDPE pipe with a velocity head at depth of 10 m.
  • Pre-treatment: Includes Travelling Band Screen, Flash Mixer, Flocculator, Lamella Clarifier, Disc Filter, and Ultrafiltration.
  • Backwash Water Treatment: Reuse of backwash water from Disc Filters, DMF, and UF in Lamella Clarifiers.
  • Desalination: Single-pass SWRO with energy recovery device (pressure exchanger) for efficient energy transfer.
  • Post-treatment: Re-mineralization with CO₂ and lime, and disinfection with Sodium Hypochlorite.
  • Capacity: Originally 100,000 m³/day, expanded to 110,000 m³/day in 2017.
  • Plant Availability: >98%
  • Energy Consumption: 3.6 to 3.78 kWh/m³
  • Potable Water Quality: TDS < 500 mg/l, LSI positive
  • Product Recovery: 45.4%