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RO Reject Recovery

Known for its success in the desalination of brackish water, Evoqua's NEXED® desalination module is also known to produce a higher recovery rate of reverse osmosis (RO) reject water.

 Success in RO Reject Recovery

​Electrochemical Desalination for RO Reject Recovery & Reuse

People in water-stressed areas commonly look to improve water recovery to minimize feed water consumption and reduce costs. Industries that require high-purity water, such as semiconductor, pharmaceutical, food and beverage processing, and power generally use RO. These RO systems produce waste brackish reject streams with high salt concentrations that can be optimized to reduce water consumption and decrease disposal costs.


Reverse osmosis (RO) is the most widely used method for removing silica from water. RO technologies are used to remove total organic carbon (TOC), suspended solids, and other contaminants from water. Many applications, specifically industrial– which rely on brackish water for operations–are turning to a once cost-prohibited alternative: ED.

For nearly a decade, we have performed extensive research and development on ED technology. During that time, we made a successful attempt to make electrochemical desalination through ED a feasible and preferred alternative to conventional RO technologies and methodologies. The project was a technology development endeavor funded by the Singapore Environment and Water Industry Programme Office (EWI) under PUB Singapore Economic Development Board (EDB). As leaders in the electrochemical industry, we made it our goal to find more efficient techniques to desalinate water.

In 2008, our scientists and engineers set new energy savings capabilities in the lab, which then led to Evoqua winning the government-initiated Singapore Challenge competition. Since then, we’ve worked tirelessly to develop a commercial version of the process. In December of 2010, we demonstrated that our new electrochemical desalination process could reach half the energy required with RO. Not only does our state-of-the-art water desalination technology use less energy, but it is also tunable and quiet, and it requires low pressure. In addition, it features a high-performance and low-cost desalting engine. Finally, it can be used in a variety of applications, including:
• Water Reuse
• Variable Salinity Applications
• Brackish Water TDS Reduction
• Reverse Osmosis (RO) Reject Recovery
• Small Footprint Bulk TDS Removal

​The Problem

RO systems are designed to decrease the level of ions in process water. Typically, RO systems recover about 75% of the water treated. While this seems like a significant amount of usable water, about 25% of the feed water is discharged as wastewater. Many combat the problem by feeding the reject water directly into another RO system. Unfortunately, there are many restrictions with biofouling, silt fouling, and scaling. In turn, this limits the recovery possible.

NEXED Module: The Solution

With the goal to reuse the reject feed water, Evoqua has developed a solition: the NEXED module. When installed, the module allows you to maximize the recovery without the worry of scaling or fouling. In fact, the NEXED module has been used to increase the overall RO recovery to 96%. By installing the module, you can reuse the water and, therefore, reduce the costs of feed water production and wastewater disposal.


 *A 15-skid pilot installation in Singapore