Comparison of RO, MED, MSF desalination water in terms of cost, energy consumption, chemical requirement of the industry

Choosing a desalination plant is not just a technical decision — it’s an economic, energy, and management decision that can change your operating costs by up to 40%.

In this comprehensive and detailed guide, we compare the three most widely used technologies, RO (reverse osmosis), MED (multi-effect distillation), and MSF (multi-stage evaporation), from three critical angles:

• Capital and operating costs
• Energy consumption
• Chemical requirements and maintenance challenges

All figures are for comparison purposes only and may change over the coming years. Our goal is to help you choose the best option for your industry, budget, and geographic conditions with real-world data and technical analysis.

Why read this article?

✅ A realistic and accurate comparison of the three main desalination technologies

✅ Understand the key differences in cost, energy, and chemical requirements

✅ Identify the best option for your industry (refinery, power plant, municipal, etc.)

✅ Avoid making the wrong choice that can multiply your operating costs

Brief introduction of the three technologies — comparison background

RO (Reverse Osmosis) — Reverse Osmosis

• Technology type: Membrane — Physical
• Heat requirement:❌No
• Capacity: Small to very large (1 to 1000+ cubic meters per day)

MED (Multi-Effect Distillation) — Multi-effect distillation

• Technology type: Thermal — Evaporation and condensation
• Heat requirement:✅Yes (60 to 70°C)
• Capacity: Medium to large (500 to 50,000 cubic meters per day)

MSF (Multi-Stage Flash) — Multi-stage evaporation

• Technology type: Thermal — Evaporative flash
• Heat requirement:✅Yes (90 to 110°C)
• Capacity: Very large (5000 to 80,000+ cubic meters per day)

Comparison in terms of energy consumption — Which technology is energy efficient?

Energy Summary:

• RO:Most energy efficient — especially with ERD — suitable for areas with cheap electricity
• MED:Thermal energy efficient — suitable for industries with excess steam (e.g. power plants) — if recovered heat is used, energy cost ≈ zero
• MSF:Most energy efficient — but at large capacities, cost per cubic meter decreases
•  

Comparison in terms of chemical requirements and maintenance challenges

Chemical Summary

• RO: Requires careful management of incoming water and anti-scale injection — but no risk of metal corrosion — Chemical cost is highest
• MED: Requires anti-scale and thermal anti-corrosion — but no membrane — More stable in the long term — Chemical cost is lower than RO
• MSF: Requires strong anti-corrosion — due to the presence of chloride and high temperature — Risk of leakage is more serious — Chemical cost is similar to RO

Which technology is suitable for which industry?

Industries with limited budget and small to medium capacity (under 5000 m3/day)

RO recommendation:

• Reason: Lower initial investment — Quick start-up — Suitable for areas without access to steam
• Example: Food, pharmaceutical, small steel plants

Industries with access to cheap steam or hot water (power plants, refineries)

MED recommendation:

• Reason: Use of recycled energy — Lowest operating cost in the long run — Excellent water quality
• Example: Thermal power plants, oil refineries — In these cases, MED is cheaper than RO!

Very large municipal or industrial projects (above 20,000 m3/day)

MSF proposal:

• Reason: High reliability — Long life — Massive production without the need for membranes
• Example: Coastal cities, large refineries, government projects

Industries requiring ultrapure water (pharmaceutical, semiconductor)

RO + EDI proposal:

• Reason: RO as pretreatment — EDI for UPW production — No regeneration chemicals

Final summary table — Quick selection based on your preference

Real example: Comparison of operating costs in a refinery in southern Iran (capacity 5,000 cubic meters per day)

Result: In this real-world project, MED is the cheapest operation, not RO.

✅Final Conclusion:

Choosing between MED, RO, and MSF is not a “one-size-fits-all” decision, and RO is not always the cheapest operation

• If you need the lowest cost setup → RO
• If you have access to recovered heat → MED — the cheapest operation in the long run
• If large capacity and high reliability are needed → MSF

With this guide, you can make a more confident decision — and avoid unnecessary costs and operational problems.