Zero liquid discharge at the world’s largest gas-to-liquid plant

Veolia has developed a unique process for recycling water generated during the gas-to-liquid transition at Shell's Pearl GTL facility so it can be fully reused on site.

The Challenge

Shell required a Zero Liquid Discharge (ZLD) facility, not only with respect to the GTL effluent water, but all other water streams had to stay inside the fence. In total, twelve different water streams were to be treated entering the Effluent Treatment Plant (ETP) at eight different locations. Five different recycled water qualities were required.


The Solution

The design-build aspect of the Pearl GTL complex effluent treatment plant was conducted by a consortium formed from a 50/50 joint venture between Veolia and Saïpem and a local construction company, Al Jaber.

Due to the size of the operation and the water scarcity in the region, Qatar Petroleum and Shell opted for a sustainable water management solution, e.g. zero liquid discharge, with the water produced in the transition from gas to liquid being led to an effluent treatment plant, where it is treated and reused in the production process. The effluent treatment plant has a capacity to handle 45,000m3/day.

Veolia designed and completed the effluent treatment plant, supported by patented Veolia technologies. In particular, wastewater will be treated by ultrafiltration and reverse osmosis, with the objective of their complete reuse within the factory process. Thus, no liquid effluent will be discharged into the natural environment. Reverse osmosis brine treatment will be carried out by evaporation and crystallization, a technology achieving zero liquid discharge where only salt crystals are produced.


Major and Ancillary Process Equipment Provided

  • Sweet and Sour CPI separators
  • Oil tankage, water tankage
  • Controlled Discharge Facility (8000m3 basin with 3m x 14m long Archimedan pumps)
  • Heat exchangers
  • Flocculation & Flotation Units
  • Aerobic biological treatment (conventional) with circular settlers (conventional)
  • Submerged Ultrafiltration
  • 3 pass Reverse Osmosis
  • Irrigation water treatment by UV
  • Waste Water Evaporators and Crystallization of concentrated waste streams (ZLD system)
  • Cooling water blowdown treatment (Submerged Ultrafiltration & Reverse Osmosis)
  • Mineral sludge dewatering with centrifuge
  • Activated sludge dewatering with centrifuge

The Client

Shell is a worldwide group of oil, gas and petrochemical companies with interests in biofuels, wind and solar power and hydrogen.

The Pearl GTL project, located in north-east Qatar, comprises the development of upstream gas production facilities as well as an onshore Gas-to-Liquid (GTL) plant that produces 140,000 barrels per day (bpd) of GTL products as well as approximately 120,000 bpd of associated condensate and liquefied petroleum gas.

Customer Benefits

  • Strict regulatory compliance
  • Smaller environmental footprint
  • Greater community acceptance

Key Figures

  • (2) Trains for the main treatment line
  • Various common facilities
  • Total hydraulic capacity (ex internal recycles): 2,200 t/h
  • Total hydraulic capacity AOC collection: 15,400 t/h
  • Total free oil in: 17 t/d
  • Total soluble COD in: 27 t/d
  • Total solids in: 8 t/d
  • Total wetcake out: 49 t/d