Reverse osmosis is a water purification process. It forces pressurized water to flow across a semi-permeable membrane, leaving behind unwanted colors, tastes, odors, salts, particulates, and other contaminants. It is used for very small particles between 0.0001 to 0.005 microns (mm), including bacteria, ions (i.e. calcium, fluoride), organic materials, salts, viruses, etc.
What is Closed Circuit Reverse Osmosis™ (CCRO)?
Closed Circuit Reverse Osmosis™ — CCRO for short — is Desalitech’s improvement on the traditional reverse osmosis process. Compared to traditional systems, CCRO achieves much higher water recovery rates (up to 98 percent), is much more energy-efficient, resists scaling, fouling, and biological growth, and has unmatched flexibility.
How does CCRO work?
During closed circuit (CC) mode, 100% of the brine is recirculated. Like a sand filter, which is backwashed to remove suspended solids, the CCRO system is flushed to remove dissolved solids. The CCRO process concentrates wastewater over time rather than space. The multiple stages of a traditional reverse osmosis design are replaced by multiple cycles in CC mode. Once the desired recovery is achieved after several cycles, the concentrated wastewater is flushed. This single-stage loop is what sets CCRO systems apart from traditional reverse osmosis designs.
Is your technology patented?
Yes. The Closed Circuit Reverse Desalination process™ is protected by 140 patents in 60 countries worldwide. Note: these patents apply only to Desalitech’s unique design. Our systems are assembled using standard, readily available, off-the-shelf components.
What is the maximum recovery offered by Desalitech's systems?
Our systems have achieved a maximum of 98% recovery while operating under real-world conditions, something no other reverse osmosis systems have achieved. Generally, they operate in the 90-95% range. In contrast, traditional reverse osmosis systems typically max out at around 75% — higher rates are possible, but at the cost of reliability and energy efficiency.
Each individual system’s maximum recovery is based on the chemistry of its feedwater, and the only real limiting factor is the feedwater’s scaling potential.
Desalitech’s Water Specialist are happy to work with you to determine the maximum recovery a CCRO system could achieve with your water.
What industries and applications are Desalitech systems best for?
CCRO systems can be used for any application traditional reverse osmosis is used — and some places it cannot (e.g. sites with varying feedwater or high silica concentrations). This makes them ideal for a wide range of applications across industries, including but not limited to Food and Beverage, Consumer Goods, Chemicals and Refineries, Power Generation, and Metals and Plastics, among others. Some of the applications include:
- industrial process water
- food, beverage, and pharmaceutical ingredient water
- boiler water pretreatment
- irrigation water desalination
- brine concentration
- municipal wastewater treatment
Because of their record-setting water recovery rates and unmatched operational flexibility, CCRO systems are especially well-suited for reducing water use and working with varying-quality water sources.
What flow rates can your systems support?
Desalitech’s standard product line is designed to handle 50–1200 gallons per minute (gpm), Custom units and train configurations are available for projects up to 1400 gpm. In 2018, we will be announcing a partnership to provide systems smaller than 50 gpm.
Do Desalitech systems require any special equipment or instrumentation?
Desalitech systems are constructed using standard off-the-shelf components and membranes and we’re happy to incorporate any component manufacturer you specify. The CCRO design features a variable-speed speed pump, which recirculates 100% of the brine during closed circuit (CC) mode. Generally, however, what sets Desalitech’s systems apart is the innovative design, not the components.
We have received letters of qualification from all major membrane manufacturers (Hydranautics, Dow, etc.) stating that their membranes are compatible with the CCRO process and how CCRO often extends the life of their membranes due to the operational characteristics.
Can CCRO systems achieve the same permeate quality as traditional reverse osmosis systems?
Yes — the quality of permeate is comparable to that of a traditional reverse osmosis system.
What is the history of Desalitech?
Desalitech was founded in 2008 in Israel, based on Professor Avi Efraty’s development of the CCRO process, formerly known as Closed Circuit Desalination (or CCD), at the University of Waterloo. In 2013, Desalitech’s founder and CEO Nadav Efraty moved the company’s headquarters to Newton, Massachusetts, just outside Boston. Since then we have been serving customers around the world.
Can I invest in Desalitech?
Desalitech is currently a private company and is not traded in any public market. Our external funding comes from venture capital and private equity concerns. If you are an accredited investor we can put you in touch with of Finance department.
How do Desalitech systems achieve such high recovery rates?
Traditional reverse osmosis systems typically achieve 75% recovery using a two-stage system design, or 87% incorporating a more complicated three-stage design. Each stage recovers 50% of its feedwater, with subsequent stages purifying the “leftovers” from the previous stage. Each additional stage produces diminishing returns and exacerbates problems with balancing water pressure across multiple stages.
Closed Circuit Reverse Osmosis eliminates these problems by using only a single stage. The CCRO process concentrates feed water in time versus space, not allowing enough time for sparingly soluble salts to precipitate. The multiple stages of a traditional system are replaced with cycles in closed circuit mode. After several cycles, the concentrated wastewater is flushed to drain. Without the constraints inherent in a multi-stage design, CCRO can achieve record-setting recovery rates as high as 98% percent.
One cycle represents the total volume of the system recirculated through the single membrane array. The time for one cycle is that volume divided by the circulation pump’s flow rate.
How do Desalitech systems resist scaling and fouling?
In any reverse osmosis system, crossflow is one of the most important factors in performance. Water flowing along (i.e. parallel to) a membrane’s surface sweeps away salts and other contaminants. High crossflow reduces scaling and fouling, but in a traditional reverse osmosis system it hampers recovery because high crossflow means potentially recoverable water is being swept past the membranes before it can pass through. In a CCRO system, crossflow can be set independently of recovery by increasing/decreasing the circulation pump flow rate. Increased cross flow decreases concentration polarization (beta), lowering the concentration at the membrane surface — and therefore the fouling potential.
CCRO systems can even push some salts into supersaturation without scaling. Different salts take different amounts of time to crystallize out of solution, even at concentrations over 100%. CCRO systems can push some salts into supersaturation as long as they flush the supersaturated waste out of the system before the dissolved salts have a chance to crystallize.
How do Desalitech systems resist biological growth (biofouling)?
Salinity and pressure are constantly cycling inside the CCRO system as the wastewater gradually becomes more concentrated before being flushed. This deprives microorganisms of the environmental stability they’d need to survive.
What makes Desalitech systems so flexible?
The software that controls our systems uses up to three different user-defined set-points to automate adjustments to the filtration process — volumetric recovery (percentage water turned into permeate), brine conductivity (salt content of waste), or maximum feed pressure.
Here’s an example. Imagine a pharmaceutical plant uses a municipal water source that switches seasonally between well water and lower-quality surface water. The plant must meet a consistent permeate quality target, despite varying-quality feedwater.
Depending on the source, the conductivity of the feedwater will change. The plant manager can enter software set-points so that the system automatically detects the conductivity change and adjusts accordingly; the filtration time and recovery rate will change, but the permeate quality will remain consistent.
This level of flexibility is unprecedented in traditional reverse osmosis systems, which are calibrated when built and cannot be adjusted on the fly.
How do Desalitech systems achieve better flux distribution?
In a legacy reverse osmosis system, several sequential membrane stages are all fed water using a single, steady-state pump. The pump must be set at very high pressure to ensure that downstream membranes get the flow they need. As a result, earlier arrays end up receiving more flux than they should, making them especially prone to fouling. While the last membranes have a low flux and limited/reduced cross flow.
In contrast, CCRO systems use a single membrane stage and increase the high pressure pump frequency with each cycle (PID loop between VFD and feed flow rate) to ensure that the membranes only get the flux they need for optimal operation. This gives you much better control and reduced energy costs.
What happens if a system stops working?
The system is designed to fail closed: if something goes wrong, permeate stops being produced and water stops flowing into your process. Before the system fails, however, our ReFlex Smart monitoring software will alert you and Desalitech of a problem so it can be troubleshot onsite by your staff, our service technicians, or remotely through our ReFlex Smart software.
Does Desalitech provide service for its systems?
Desalitech’s Customer Success and Service Team supports warranty claims and service contracts around the world. We have technicians staffed across the U.S. and Israel and trained partners around the world. In addition, all of our systems are shipped with ReFlex Smart software which allows most problems to be troubleshot remotely with help from our trained engineering staff.
What is the normal lifespan of a Desalitech system?
The industry standards for reverse osmosis systems are a 10 years lifespan when processing brackish water and 20 years when processing seawater. Our systems are built from standard components, so our life cycles are comparable to traditional systems.
How does the average permeate flux rate in Desalitech systems compare to legacy reverse osmosis systems?
The average rate of permeate production is comparable to traditional reverse osmosis, but there may be brief fluctuations in permeate production when concentrated brine is flushed from the system with raw feedwater. Plants with polishers downstream of a CCRO system may experience issues with this flow inconsistency. This can be addressed using a break tank and distribution pump immediately following the CCRO system. Another solution is to hold the permeate flow rate constant by increasing the recovery and feed flow rate during the flush (PF mode).
How does the typical power consumption in CCRO systems compare to traditional reverse osmosis systems?
CCRO systems use significantly less power than traditional reverse osmosis systems. In a traditional multi-stage reverse osmosis system, a single pump operates at a constant, predetermined pressure. It needs to provide enough pressure for the downstream stages, even though earlier stages need much less pressure to drive effective reverse osmosis. This wastes energy.
In a CCRO system, the variable-pressure pump only provides as much pressure as is needed for optimal recovery in a given cycle. Furthermore, because our single stages use fewer, shorter membranes than traditional reverse osmosis, our starting pressure is much lower.
Should a CCRO system be piloted prior to construction and start up?
No, it is generally not necessary. The CCRO process is accurately modelled by LewaPlus software, and these models have been validated in the field. Furthermore, the CCRO design is inherently flexible — the mechanical design is the same whether it is being run at 75% or 98% recovery. This flexibility, coupled with an inbuilt resistance to scaling and fouling, means that setting up a CCRO system without a pilot is presents a lower risk than setting up a traditional system without a pilot.
Do the membrane design guidelines for Desalitech systems differ from legacy reverse osmosis systems?
CCRO systems follow the same membrane design guidelines as traditional reverse osmosis systems. However, it is easier to keep CCRO systems operating within the recommended parameters for membranes because of the inherent flexibility of the process.
For example, if concentrate flow rate per pressure vessel is below the recommended value, you can simply decrease the ‘CC recovery’ parameter, which will directly increase the circulation pump flow rate. In contrast, a traditional system faced with the same problem would require permeate throttling, trying to balance the number of pressure vessels per stage, and/or adding concentrate recirculation.
Where are Desalitech systems manufactured?
As of 2017, we have eight qualified fabricators. Four are based in the U.S., one in Canada, one in Australia, one in Israel, and one in Malaysia. Key component fabricators are also located in Canada and China.
Do I need to have a design validated by Desalitech prior to construction and start up?
Yes. The CCRO process is patented, so a license is required to build systems — at which time, the design will be validated.
Can any OEM build a Desalitech system using CCRO process technology?
A license is required to build systems, but the design itself is straightforward and uses standard components. If you have a preferred manufacturer, please contact Desalitech to discuss the purchase of a license and to receive a design package.
Desalitech system designs include extra piping. Why?
The piping provides extra volume so that the total system volume can be adjusted. System volume is directly related to sequence time. The normal closed circuit sequence time is 5 minutes. If you need to increase or decrease this value, we recommend increase vessel length or decrease elements per vessel. We recommend you leave the default setting.