ICP vs. Reverse Osmosis
Two ways to treat cooling tower blowdown.
Reverse osmosis pushes water through a filtration membrane at high pressure. Ion Concentration Polarization uses an electric field to separate dissolved ions into demineralized and concentrated streams. For concentrated cooling water, that changes the pressure, fouling, and maintenance equation.
Reverse Osmosis
- Pushes water through a membrane at application-specific high pressure
- Membranes scale, foul, and need replacing
- Rejects a concentrate stream you have to dispose of
ICP (RECOVER)
- Separates ions with an electric field in a low-pressure flow channel
- Bulk water does not pass through a filtration membrane
- RECOVER targets 90% return of treated cooling tower blowdown
Nona's September 2026 RECOVER technical sheet specifies 5–30 PSI operation. ICP was developed at MIT; site chemistry determines fit.
Short answer
Reverse osmosis pushes water through a filtration membrane at high pressure. Ion Concentration Polarization uses an electric field and ion-selective membranes to create demineralized and concentrated streams. For cooling tower blowdown, ICP offers a low-pressure path designed for concentrated water where membrane fouling and maintenance can complicate RO.
ICP is the technology behind NONA RECOVER for data-center cooling water recovery and the practical cooling tower blowdown recovery guide.
Reverse osmosis is mature, widely available, and effective in many desalination and reuse systems. For large centralized plants, stable feedwater, established pretreatment, and experienced membrane operators, RO may remain the practical choice. ICP fits a narrower problem: distributed treatment of concentrated water where low pressure, fouling tolerance, and maintenance affect total operating cost.
The mechanism
How ICP works
ICP uses an electric field applied across a narrow channel to move dissolved ions, the minerals that make blowdown water difficult to reuse, away from one part of the water stream. The channel separates into a demineralized stream and a concentrated stream.
ICP uses ion-selective membranes to create the separation zones, but the bulk water does not pass through a filtration membrane as it does in reverse osmosis. Nona's RECOVER system operates at roughly 3 PSI and room temperature.
How ICP works
Reverse osmosis pushes water through a membrane. ICP pulls the minerals out of it.
Reverse osmosis pushes water through a filtration membrane at high pressure. Ion Concentration Polarization, developed at MIT, uses ion-selective membranes to create separation zones while the bulk water remains in the flow channel. Here is what happens inside a RECOVER skid.
Apply a small electric field
RECOVER runs blowdown through a low-pressure flow channel beside ion-selective membranes. An electric field moves dissolved ions across the membranes.
Pull the dissolved minerals aside
The field creates ion-depleted and ion-enriched zones that move dissolved salts and minerals to different parts of the flow.
Split into clean and concentrated streams
The flow divides into treated water and a concentrated stream. Bulk water does not pass through a filtration membrane, but ICP does use ion-selective membranes that require maintenance.
Return clean water to the loop
Treated cooling tower blowdown returns to the loop. RECOVER's design target is 90% return of that liquid stream, subject to site chemistry and operating conditions.
Head to head
ICP vs. reverse osmosis vs. thermal
Operating pressure
- Nona ICP
- RECOVER: 5–30 PSI technical range
- Reverse Osmosis
- Application-specific high pressure
- Thermal
- Heat-driven (not pressure)
Energy requirement
- Nona ICP
- Low-pressure electric field
- Reverse Osmosis
- High-pressure pump
- Thermal
- Heat-driven
Fouling risk
- Nona ICP
- Reduced filtration-membrane fouling risk
- Reverse Osmosis
- Feed contacts filtration membrane
- Thermal
- Scaling remains a design factor
Chemical pretreatment
- Nona ICP
- Site specific
- Reverse Osmosis
- Often used to protect membranes
- Thermal
- Site specific
Water recovery rate
- Nona ICP
- RECOVER: 90% treated blowdown return target
- Reverse Osmosis
- Feed and system specific
- Thermal
- System specific
OpEx
- Nona ICP
- Site specific
- Reverse Osmosis
- Site specific
- Thermal
- Site specific
Retrofit complexity
- Nona ICP
- Site-specific side-stream retrofit
- Reverse Osmosis
- Site-specific
- Thermal
- Site-specific
ICP vs. reverse osmosis: common questions
Straight answers for engineers comparing Ion Concentration Polarization to reverse osmosis for cooling water recovery.
What is Ion Concentration Polarization?
Ion Concentration Polarization is an electrochemical separation process. An electric field and ion-selective membranes create an ion-depleted stream and an ion-enriched stream, which are separated into treated water and concentrated reject.
Does ICP use membranes?
Yes. ICP uses ion-selective membranes to create the electric field and separation zones. The important distinction is that the bulk water does not pass through a filtration membrane as it does in reverse osmosis.
Is ICP an alternative to reverse osmosis?
Yes, for some applications. ICP is an electrochemical alternative where low pressure, concentrated water, fouling tolerance, and distributed operation matter. Reverse osmosis remains appropriate for many well-characterized desalination and reuse systems.
Which is better for cooling tower blowdown?
It depends on water chemistry, treatment chemicals, target recovery, reject handling, energy, maintenance, and available space. RECOVER applies ICP to concentrated cooling water where membrane fouling and high-pressure operation can make reverse osmosis difficult.
How much water does RECOVER recover?
RECOVER is designed to return 90% of treated cooling tower blowdown to the loop. Nona's September 2026 technical sheet gives an 85–90% recovery range; site makeup water and cost outcomes depend on measured flow and chemistry.
Does RECOVER replace evaporative cooling?
No. RECOVER works alongside the existing cooling tower. It treats the blowdown stream and returns recovered water without changing the facility's heat-rejection design.
What pressure does RECOVER use?
Nona's September 2026 RECOVER technical sheet gives a 5–30 PSI operating range. Pressure depends on the feed and system operating point; this is a RECOVER range, not a universal ICP specification.
Is ICP proven outside the lab?
ICP was developed and patented at MIT. Nona has engineered it into RECOVER hardware and demonstrated the system with Tracy Renewable Energy.
Sources & references
ICP was invented, peer-reviewed, and patented at MIT, and its development was funded by the U.S. Army. The figures on this page trace to the primary sources below.
- From seawater to drinking water, with the push of a button
MIT News (2022), on how ion concentration polarization removes salts and particles without filters or high-pressure pumps.
- Off-grid portable ion concentration polarization desalination unit
MIT Abdul Latif Jameel Water and Food Systems Lab (J-WAFS), the research program behind ICP and Nona.
- Portable Seawater Desalination System for Generating Drinkable Water
Yoon, Kwon, Kang, Brack and Han, Environmental Science & Technology, ACS (2022). Peer-reviewed ICP performance data.
- Return Flow System for Ion Concentration Polarization (ICP) Desalination
MIT Technology Licensing Office, US Patent 11,780,754, exclusively licensed to Nona Technologies.
- How J-WAFS Solutions grants bring research to market
MIT News (2025), covering Nona's commercialization, U.S. Army collaboration, and industrial demonstration.
Compare treatment against your water chemistry.
Share your cooling load, blowdown flow, and water chemistry. Nona's technical team can review where ICP fits, what pretreatment is needed, and how to model a site-specific recovery estimate.