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Solutions

Zero liquid discharge at a fraction of the thermal cost

Osmosys membrane trains concentrate industrial and municipal brines to 280,000 mg/L before crystallization, reducing the evaporator and crystallizer to a small finishing step.

Reverse-osmosis pressure vessels in a treatment hall
Lower energy and capital than a thermal train
60–75%
Water recovered across the membrane train
99%+
Smaller plant footprint
70%

The challenge

Discharge limits are tightening across the GCC, China, India, the European Union, and the United States. Conventional reverse osmosis stops at about 90,000 mg/L, so the remaining concentration has been done thermally, at 25–60 kWh per cubic metre of water removed.

  1. Energy

    Evaporators and crystallizers dominate the operating cost of a ZLD plant.

  2. Capital

    Thermal equipment in corrosion-resistant alloys sets the project budget.

  3. Footprint

    Thermal trains are large, which rules them out on constrained and underground sites.

Approach

The membrane ZLD train

SEBRO, SAMRO and the MemBrine Concentrator each operate in their own salinity range. Most of the water is recovered on membranes; only the final residue reaches the crystallizer.

Typical configuration. Stream values for each project are set by its design basis.

Osmosys membrane scope1234FeedPretreated per chemistrySEBROSemi-batch RO→ 25,000 mg/LSAMROSalinity-adaptive→ 90,000 mg/LMBCBrine concentrator→ 280,000 mg/LCrystallizationSized for the residueRecovered water99%+ of feed5SolidsResidue only6
  1. 01Feedindustrial or municipal water; pretreatment set by the chemistry
  2. 02SEBRO concentrate25,000 mg/L
  3. 03SAMRO concentrate90,000 mg/L
  4. 04MBC concentrate280,000 mg/L · 5–12 kWh/m³
  5. 05Recovered water99%+ of the feed across the train
  6. 06Solidscrystallizer sized for the residue only
Process flow diagram with stream table
StreamNameDetail
1Feedindustrial or municipal water; pretreatment set by the chemistry
2SEBRO concentrate25,000 mg/L
3SAMRO concentrate90,000 mg/L
4MBC concentrate280,000 mg/L · 5–12 kWh/m³
5Recovered water99%+ of the feed across the train
6Solidscrystallizer sized for the residue only

Routes to zero liquid discharge

Concentration ceiling
Conventional RO: ≈90,000 mg/L
Thermal only: No technical limit
Osmosys membrane train: 280,000 mg/L
Specific energy
Conventional RO: 2.7–4 kWh/m³
Thermal only: 25–60 kWh/m³
Osmosys membrane train: 5–12 kWh/m³
Thermal duty
Conventional RO: Whole flow
Thermal only: Whole flow
Osmosys membrane train: Residue only
Reaches ZLD
Conventional RO: No
Thermal only: Yes, at high cost
Osmosys membrane train: Yes

What it delivers

  1. Compliance

    Zero or minimal liquid discharge, depending on the permit. The final stage can be added later.

  2. Operating cost

    5–12 kWh/m³ for membrane concentration, against 25–60 kWh/m³ thermally.

  3. Recovered water

    More than 99% of the feed returned as reusable water across the full train.

  4. Standard equipment

    Spiral-wound membranes and pressure vessels from established suppliers.

Project

King Salman Park: zero liquid discharge at municipal scale

King Salman Park, Riyadh, Saudi Arabia

Treating 10,800 m³/day of CCRO® brine at 36,772 mg/L TDS to over 200,000 mg/L, in a footprint 70% smaller than conventional systems, for the world’s largest urban park.

Brine treated
10,800m³/day
Water recovery
82%
Smaller footprint
70%
Read the case study

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