PX Pressure Exchanger

Water Products Catalog

energy recovery devices (ERDs), reducing the energy needs, costs, and emissions associated with reverse osmosis desalination.

Energy Recovery has spent decades perfecting devices that capture and recycle otherwise wasted pressure energy. We have a suite of energy recovery devices (ERDs) that can operate at different pressures, dramatically reducing the energy needs, costs, and emissions associated with reverse osmosis desalination.

Our industry-leading energy recovery solutions include the PX® Pressure Exchanger®, Ultra PX™, and Turbocharger. Combined with our family of pumps, our solutions are trusted around the world by plants of all sizes to meet their specific energy recovery needs.


Energy recovery technologies such as the pressure exchanger (PX), have previously focused on seawater RO applications due to the rather quick payback. This leaves brackish water RO (BWRO) facilities to turbochargers that yield less efficient transfer of energy than their PX counterparts. Recently, the first municipal BRWO application of a PX energy recovery device was designed for the City of North Port, Florida’s Southwest Water Treatment Plant and will be started up in 2nd quarter 2022.

This will be the first Brackish Water municipal installation of the Brackish pressure exchanger within the U.S. This paper will present and discuss the design considerations and key parameters including impacts to RO system operation and water quality, energy saving considerations, and data from the facility startup in 2nd quarter 2022. Municipalities with brackish-water supplies will be shown the way to reduce operating costs and maintain water quality from their RO treatment facility.

PX Q Series

For over 20 years we’ve enhanced our PX technology to meet rapidly evolving customer needs. We’re taking the next step with an expanded PX Q Series, which delivers minimal noise levels alongside the best-in-class performance and efficiency that customers can expect from our flagship PX product line. The Q220, Q180 and Q140 models join the Q300 and Q260 to serve a broader range of plant sizes. With operational sound levels below 79 decibels, the PX Q Series improves the auditory environment while also delivering industry leading uptime and energy savings. Download the one-sheet for more details.


Available in multiple configurations, the PowerPlay raises the bar on SWRO plant performance. Constructed with state-of-the-art technology, each component of the PowerPlay is virtually maintenance free and backed with service from a single, trusted source. Download the one-sheet to learn more.

Animation: How the PX Pressure Exchanger Works

With over 15,000 PX devices installed worldwide, the PX Pressure Exchanger technology sets the standard for excellence in engineering. This game changing technology cuts energy costs by 60% – saving our clients billions of dollars every year and helping to produce over 12 billion liters of fresh water every day. Watch to learn more.

PX Prime Brief

This one-page brief provides an overview of the PX Prime, the best energy recovery solution for desalination, now available risk-free.

PX Prime Teaser

Over two decades, Energy Recovery has earned a leading position in the global water market. Our groundbreaking PX Pressure Exchanger is the most widely used energy recovery device in the world.

The PX Prime is the latest advancement in Energy Recovery’s award winning PX Pressure Exchanger line, and is the most advanced energy recovery device for desalination available on the market. We have engineered the PX Prime to perform with even less fluid mixing and enhancements across a variety of factors. It will also be the first PX available risk-free, with no upfront costs.

Desalination During Drought: Solutions to a Growing Demand for Water

Clean drinking water is fundamental to all life. As 2015 marks the end of the United Nations’ International Decade of Action recognizing water and sanitation as a basic human right, it also marks the beginning of a new era of water supply and usage across the state of California.

Since a statewide drought began four years ago, California lawmakers have struggled to find rainfall-independent solutions. This is not the first time California has turned to desalination as part of a larger plan to tackle decreasing water levels and drought conditions. The multiple-year drought in the 1980s led to the construction and opening of the Charles E. Meyer Desalination Plant in Santa Barbara. When rainfall returned just three months after the plant opened, the facility was mothballed. Forward-thinking experts kept up plant maintenance in the meantime, knowing it would not be the last time such measures would be considered or implemented.

There are also costs and other types of resource usage issues to consider. For instance, much of Southern California’s drinking water travels hundreds of miles from its origin in the Colorado River, transported using a massive and expensive aqueduct and conveyance system. With this current drought comes an opportunity to revisit tabled solutions and better prepare future plans to make desalination part of a larger framework to continue to keep California watered.

Desalination is not a silver bullet. But technology has improved the process and subsequently lowered the cost. Stuart White, director of the Institute for Sustainable Futures in Sydney, Australia, has called the need to plan for future plants “desalination readiness.” In Australia, as in many other arid, desert-like parts of the world, desalination has become a necessary and useful part of a plan to increase water resiliency and drought preparedness. The capacity of large desalination plants is quantified by how many millions of gallons of water per day (MGD) the plant produces, with Sorek, the world’s largest seawater reverse osmosis plant located south of Tel Aviv, producing 165 MGD. The largest desalination plant using membrane technology, which typically uses energy recovery devices such as the PX Pressure Exchanger, is Magtaa in Algeria, with a capacity of 132 MGD.

In the following pages, we’ll consider the success stories of desalination in California coastal cities, in Israel, and in Perth, where desalination helped pull the Australian city back from the brink of disaster during a decades-long drought. We’ll also look at other examples that circle the globe. Spain recycles 17 percent of its effluent, the second highest percentage worldwide after Israel, which treats 86 percent of its wastewater and irrigates more than half its crops with treated effluent. Domestically, states with desert climates, including Texas, are considering adding desalination plants to their resource management portfolio as a way to stay ahead of disaster and move ahead with progressive, affordable technological solutions to an age-old problem.

Energy Recovery in China

China has been turning to seawater reverse osmosis (SWRO) as a way to ease the severe stress on fresh water resources, and ninety percent of Chinese desalination plants use Energy Recovery’s technology to harness fluid flows and pressure energy. Watch this video to hear experts in the Chinese desalination industry talk about their experience with Energy Recovery over the past ten years.

Chinese version available


面对日益严峻的水资源短缺,中国各水利机构与各大全球水处理公司建立了合作伙伴关系,致力于建造 中国现今最大的反渗透海水淡化厂。美国能量回收公司始终为主要的海水淡化厂提供高效领先的能量回收设备,并 在中国拥有90%的市场占有率,每日供水估约50万立方米。

PX Power Model

Energy Recovery’s Power Model simplifies the task of predicting power consumption when using process parameters, turbines and membrane recovery rates. This application calculates the pressures and flows, thereby estimating the power consumption of each pump in a reverse osmosis desalination system. The Power Model can estimate pump and motor efficiencies for most systems or enter your information manually.  Simply follow these steps to get your plant’s results.

ERI-SIM v1.3

ERI-SIM simulates the processes in a seawater reverse osmosis (SWRO) plant. It models the pressures, flows, and salinities of a seawater RO process equipped with Energy Recovery’s PX energy recovery devices. ERI-SIM integrates PX device performance, typical pump and valve characteristics, and projected membrane responses into an interactive, dynamic training model. Note that ERI-SIM is for training purposes only and is not a design tool.

YuHuan, China powering up for 2008 Olympics

The Industry Standard Solution

The efficiency and life cycle costs of a plant’s energy recovery technology is critical to both securing SWRO projects and achieving maximum plant profitably through the lowest operating costs. Leading international OEM’s such as Acciona Agua, GE Water Process and Technologies, Siemens and Suez Degrémont have selected the PX modular technology for their SWRO projects because it consistently achieves real energy transfer efficiencies— up to 98%, making it the most efficient energy recovery device available today. At the core of the PX device is a single moving rotor made of tough engineered ceramic that is unaffected by chemicals, will not corrode, and requires no periodic maintenance. Over 80 OEMs are standardizing on PX technology with installations around the world, including plants such as Al Shuaibah III, Barcelona, Chennai, Hamma, Perth, Skikda, Torrevieja and Yuhuan.

YuHuan Project Facts

  • Capacity: 36,000 m3/day
  • 6 trains – 6,000 m3/day
  • 6 PX-220 Pressure Exchangers per SWRO train
  • 97.2% efficiency guaranteed
  • Plant went online in 2006

YuHuan, China Power Station

The desalination facility in China’s Zheijang Province is the largest desalination project in Mainland Asia. The plant, built by Beijing CNC Technology, Inc. supplies process water to new electrical power stations. The OEM’s decision to use Energy Recovery’s PX Pressure Exchanger® technology for the YuHuan desalination plant helped prepare the country for its 2008 Olympics. The 1,800 MW power stations expanded China’s electrical grid capacity in preparation for the 2008 Olympics. Rapid growth of the economy in China has stretched availability of electric power. Desalinating seawater by conventional “waste heat” recovery methods consumes a significant portion of a power plant’s energy input. Compared to conventional technology, the PX device cuts the amount of energy required to desalinate seawater for power plants by up to 68%. The use of PX technology at the YuHuan desalination plant enables the reduction in desalination plant power demand of over 4.4 MW- saving over $2.0 million per year. Other desalination plants, such as Beijing’s CNC 5,000 m3/day SWRO plant at China Petrochemicals Dalian built in 2003 also uses the PX device. The East China Electric Power Design Institute Ministry (ECEPDI) and Beijing CNC specified Energy Recovery’s PX-220s for YuHuan based on the proven high efficiency and two-year trouble-free track record of the PX-220 installation at Dalian China Petrochemical. Because of its 98% energy efficiency solution, China now leads the world in the adoption of efficient PX technology with close to 100% market share.

Hear about our work from Chinese water authorities in this video.

YuHuan Power Station SWRO Desalination Project

Energy Recovery (NASDAQ: ERII) develops award-winning solutions to improve productivity, profitability, and energy efficiency within the oil & gas, chemical, and water industries. Our products simplify complex systems and protect vulnerable equipment. By recycling fluid pressure that would otherwise be lost in critical processes, we save clients more than $1.4 billion (USD) annually. The PX Pressure Exchanger is a rotary positive displacement pump that recovers energy from the high-pressure waste stream of sea water reverse osmosis (SWRO) systems at up to 98% efficiency with no downtime or scheduled maintenance. Headquartered in the Bay Area, Energy Recovery has offices in Barcelona, Shanghai, and Dubai.

The world’s largest energy recovery device manufacturer delivers:

  • Proven SWRO Power Consumption as Low as 1.7 kWh/m†
  • No Scheduled Maintenance Shutdown
  • No Pulsations, or Complicated Controls
  • The Simplest Solution to Lowest Lifecycle Costs
  • Flexibility, Proven Reliability and Real Savings


White Paper: Keys to High Efficiency, reliable performance and successful SWRO operations

Isobaric energy recovery devices (ERDs) have attained nearly universal acceptance by the seawater reverse osmosis (SWRO) desalting world. These devices are operating in the largest SWRO trains in the world and continue to be an integral component in small, containerized systems. Systems incorporating isobaric ERDs are being installed and supported on all seven continents. This has lead to an accumulation of a wealth of knowledge based on practical operating experience.

White Paper: Desalination and energy efficiency for mining in Namibia

The authors present energy-saving solutions for desalination water supply for mining applications. Detailed design data for the Uranium mining desalination plant are given. Environment and economic conscious owners and operators will learn methods of design and operation of desalination systems in mining, which can be easily extrapolated to many other industrial needs, and how to minimize the total cost of ownership of a desalination process.

Turkey’s industrial water needs restrained by expensive power

Location: Istanbul, Turkey
Project: Colakoglu Metalurji A.S.
Capacity: 9,600 m³/ day
Energy Savings: $USD 800,000 or 6.2 million kWh/year* CO2 savings: 3,627 tons/ year**
* energy savings estimates based on Turkey’s power cost of $0.13/kWh
** based on Energy Recovery’s proprietary Power Model analysis

The Challenge: 
Industrial Water Needs Restrained by Expensive Power

The quality and availability of freshwater supplies in Turkey are unpredictable.  This is because rainfall variations, geographical irregularities, urbanization, industrialization, and agricultural modernization all complicate water use for human, industrial, and agricultural purposes. Turkey has no natural oil or gas resources and must make deliberate and thoughtful decisions about its energy acquisition and use. In designing Turkey’s largest desalination plant for Çolakoglu Metalurgi Company in Istanbul, Aquamatch considered many energy-saving options including DWEER and selected Energy Recovery’s technology over the competition because it saves the most energy, has the highest efficiency, and requires little to no maintenance.

The Innovation Solution
: Energy Recovery PX Pressure Exchanger

The isobaric energy-recovering PX technology captures and recycles energy.  This innovation reduces the energy required for desalination, lowers capital costs by complementing a smaller pump, decreases the carbon footprint of desalination processing, and offers maintenance-free operation for the life of the plant. The PX device made the most financial and environmental sense for the plant since it offered Aquamatch the highest return on investment for the life of the plant.

The Result
: Energy Savings Mean Viable Independent Water Source

The considerable energy saved using PX technology means Aquamatch is able to supply the Çolakoglu Metalurgi Company with more affordable process water, leaving freshwater resources available to residents. Increasingly, industrial customers seek out Energy Recovery for these benefits: companies require an independent water source that does not disrupt municipal supplies and that minimizes cost and energy use. In the case of Istanbul’s SWRO plant, Aquamatch is making economic growth possible by reducing the plant’s energy needs by more than 6 million kWh of energy per year. This has lowered the annual cost by nearly $800,000 each year for the seven years the PX solution has been operating in Turkey.
EPC contractors all gave the same answer when Aquamatch and Colakoglu Metallurgy asked for information on building an environmentally friendly and efficient desalination plant: Energy Recovery.

Tianjin’s progress stalled without water

Location: Tianjin, China
Project: Tianjin Dagang Seawater Desal Plant
Capacity: Capacity: 100,000 m³/ day scaling to 150,000 m³/d
Energy Savings: US$7.45 million or 74.5 million kWh/year*
CO2 savings: 44,000 metric tons/year**
* energy savings estimates based on China’s power cost of $0.10/kWh
**based on Energy Recovery’s proprietary Power Model analysis

The Challenge: 
City’s Industrial Progress Stalled without Water

Limited water resources were holding back social and economic development in Tianjin Dagang, the largest industrial city in Northern China. An early adopter of desalination to meet municipal and industrial water needs, Tianjin sought to develop a massive desalination plant to enable a large, new industrial development. Building a water processing plant with an initial output of 100,000 m3/day and a future goal of expanding to 150,000 m3/day demanded seawater reverse osmosis (SWRO) technology that could efficiently desalinate and purify water.

The Innovation Solution
: PX Pressure Exchanger 220

In collaboration with Hyflux Pte Ltd., Energy Recovery created a cost-effective solution that allows the new Tianjin Dagang SWRO plant to generate huge quantities of water for its industrial customers. Though they had used competitors’ isobaric energy recovery devices in smaller installations, Hyflux built and commissioned the Tianjin plant to include the PX Pressure Exchanger® because the life cycle advantage to the PX technology includes efficiency, durability, and a track record of being maintenance free. The installed PX solutions reduce the required pump output by 55%, recycling massive amounts of fluid and pressure flows into energy and cost savings for China’s largest SWRO processing installation.

The Result
: Industrial Success and Local Jobs from Efficient Water Desalination

From the beginning of operation, Tianjin Dagang’s SWRO plant has achieved high efficiency and significant energy savings in excess of 74 million kWh each year. The PX trains are also reducing Tianjin SWRO’s CO2 emissions by approximately 44,000 metric tons each year – an equivalent of taking nine cars off the road in the US for one year. An Energy Recovery team that completed a one-year check on the installed PX trains found no measurable change in performance after a year of full capacity water production. Recycling energy from fluid flows to offer Tianjin a source of clean, reliable, affordable water has meant industrial development and the resulting economic benefits to the area are now more than possible—they are reality.

The lifetime durability of ceramic PX energy recovery devices

In order to ensure the long-term and trouble-free lifetime of the seawater reverse osmosis (SWRO) process and its enabling technology, it is essential to utilize the most advanced and reliable materials of construction. One of the more advanced and unique materials currently in use in SWRO desalination applications is high purity (>99%) aluminum oxide (alumina) ceramics. Due to its hardness, self-lubricating properties, high compressive strength and chemical resistance, alumina ceramics create an ideal fluid bearing for the rigors of seawater applications, which perform in conditions that combine corrosive and potentially two-phase (solid/fluid) environments.

High purity alumina ceramics developed and manufactured by Energy Recovery are particularly unique because of the innovative design of the company’s PX devices and the intense conditions of SWRO plants in which they operate. When in use, the ceramic-based devices are supported by a seawater fluid bearing while rotating and being pressure-cycled millions of times per year. The durability of ceramics in high-pressure, corrosive seawater environments is fundamental to the success of these devices and is quantified and categorized throughout this paper. The enhancement of ERI material science and technological improvements has shown to improve the overall durability of the product and significantly reduce sound levels to below 81 decibels.

Technical data shows that at peak rates, Energy Recovery ceramics inside the PX device wear at less than 3 microns per year (.003 inches over 25 years). The findings identify wear and prove that ERI alumina ceramics can last longer than 25 years in a seawater desalination reverse osmosis plant.

More than 15,000 PX units have been installed worldwide. Some units have been in operation for as long as 12 years. With zero failure as a result of PX technology designed ceramics, research indicates that PX devices will continue operating well into the future.

The economics of downtime

A key cost that is seldom estimated during evaluation of various technologies in seawater reverse osmosis (SWRO) projects is the cost of downtime, both planned and unplanned. This paper will prove that these downtime costs are significant to both the investors and the operators of the plant. Therefore, plant availability must be a primary factor to be considered in the design phase. Plant availability is even more critical in evaluating the energy recovery technologies as they can cripple production if they break down often and require high maintenance.

Energy recovery devices (ERD) cost less than 2% of initial capital costs but could cost twice that due to lost margin and capital costs. Due to large initial capital expenses, long project life, and criticality of water for end-users, every component should be designed for longevity and robustness along with highest performance. As many plant operators have to pay for liquidated damages when missing the minimum production requirements, it is imperative that the plant is designed for the highest availability possible.

The advantage of reliable ERD technologies

Availability can be defined as the probability that a system or piece of equipment when used under the specified conditions operates satisfactorily at any given time. The availability of the equipment installed in a seawater reverse osmosis facility (SWRO) is extremely important to the price, quality, and quantity of the final product—water. There are three critical components in the SWRO processes; the main high-pressure feed pumps, the RO membranes, and the energy recovery device (ERD) system. This paper focuses on the economic benefits and importance of the availability of energy recovery devices in SWRO desalination plants.

The largest operating expense for an SWRO facility is the power consumed, which accounts for approximately 30% of the total RO operating expense. Typically for large facilities (>50,000m3/d), the ERDs responsible for reducing energy consumption are only a fraction of the initial capital cost (~1-2%) of the entire plant, but offer major return on investment through energy savings.

The role that ERDs play is undeniably critical to success or failure of an RO facility.

Highly efficient energy recovery devices

Energy Recovery Devices (ERDs) are at the core of saving energy in the operation of any seawater reverse osmosis (SWRO) desalination facility. Isobaric or “positive displacement” devices such as the PX Pressure Exchanger devices are the most efficient solution available today and can reduce the energy consumption of seawater reverse osmosis (SWRO) systems by up to 60 percent.

Energy Recovery has the largest installed base of ERDs in the industry. Considering only large desalination plants, the Company has a global installed base of over 15,000 individual PX devices in more than 500 desalination plants. Factory acceptance testing is done on 100% of the PX devices.

This paper will examine and quantify the efficiency of PX devices based on an extensive database of actual test results. Significant historical performance data was evaluated and analyzed to validate efficiency figures and guarantee increased efficiencies for several PX device models, including the PX Pressure Exchanger models PX-220, PX-260 and PX-300 units. The existing models offer 96.8% efficiency guarantees, which in turn offer significant energy savings for plant owners and operators. Test data will also quantify the efficiency gains provided by Energy Recovery’s Quadribaric technology.

The company’s newest device, the PX-Q300, incorporates the innovative Quadribaric technology, which doubles the number of pressure exchanges per revolution. This new PX-Q300 improves efficiency—with a warranted minimum efficiency of 97.2%.

Many of the globally installed units have been in operation for as long as 12 years. With zero failure as a result of PX technology designed ceramics, research indicates that PX devices will continue operating well into the future.

Egyptian water production at odds with demands to lower power use

Location: Marsa Alam, Egypt

Project: Marsa Alam Water Plant

Product Configuration: PX Pressure Exchanger 300 and VP3471 booster pump

Capacity: 1,500 m3/day

The Challenge: Water Supply Needs at Odds with Regional Demands to Lower Power Use

The shoreline of the Red Sea is a dazzling destination for tourists and locals to experience the beach and enjoy marine activities. In Egypt, the shoreline sprawls from the Suez Canal in the north, down to the southern part of the country bordering Sudan. Though most of Egypt’s population has traditionally lived in the Cairo metro area, migration trends show more and more residents are relocating to the coastlines. Given this migratory development, small coastal towns like Marsa Alam on the Red Sea now have huge demands to supply potable water to a growing population. Until recently, the Red Sea Water and Sanitation Company was operating an outmoded SWRO desalination plant and any increase in production would require a retrofit of the existing plant. In addition to the much needed plant upgrade, the Red Sea Water and Sanitation Company was tasked by regional authorities to simultaneously lower its power consumption.

The Innovation Solution: Retrofit with Energy Recovery’s PX300 and VP3471 booster pump

To solve the plant’s main issue of high power consumption, the upgrade of the old 500 m3/day plant to increase capacity to 1,500 m3/day required a high-efficiency solution. The Red Sea Company implemented two of Energy Recovery’s PX®300 Pressure Exchangers with a booster pump to optimize the plant’s energy usage. Energy Recovery’s Aftermarket Sales and Service and their proven track record of superior customer service, coupled with the maximum availability of the PX Pressure Exchangers, provided a win-win solution for the Red Sea Company.

The Result: Dramatic Energy Savings and Surge in Water Availability

By upgrading the Marsa Alam Water Plant with Energy Recovery’s PX300, the Red Sea Company witnessed immediate reductions in total power consumption at the plant. The plant is now able to run at fully upgraded capacity using only one diesel generator set instead of two: a huge contribution to the overall energy savings. Furthermore, the project return on investment and implementation was exceptional, and the Marsa Alam region now has an abundant supply of fresh drinking water for its residents.

“By retrofitting with Energy Recovery’s PX300, the return on the investment has been remarkable. The Energy Recovery support team served as expert advisers and demonstrated that we could significantly lower power consumption by two-thirds of previous levels – all without affecting water production.”
– Ragb Sobhey
Desalination Sector, Red Sea Water & Sanitation Company

Desalinated water powers China’s economic growth

Location: YuHuan, Zheijang Province, China
Project: YuHuan Power Plant
Capacity: 36,000 m³/ day
Energy Savings: US$ 2.7 million or 27 million kWh/year*
CO2 Savings: 16,000 metric tons/year**
* energy savings estimates based on China’s power cost of $0.10/kWh)
**based on Energy Recovery’s proprietary Power Model analysis.

The Challenge: Desalinated Water Powers China’s Economic Growth

As electricity production increases in China to keep pace with the nation’s rapid economic growth, power providers are caught in a bind: energy generation requires processed water, but desalinating seawater to feed power plants requires significant energy. The 4,000 MW power stations expanding China’s electrical grid in preparation for the 2008 Olympics required a seawater reverse osmosis (SWRO) plant capable of processing significant quantities of water and a careful balance of energy considerations. Beijing CNC Technology, Inc. built the YuHuan desalination facility in Zheijang Province as the largest desalination project to address the water needs of the new power generating plants. The client wanted to avoid the power drain of waste-heat processing and take advantage of reverse osmosis’ higher yields.

The Innovation Solution: PX Pressure Exchanger 220

To save energy and money, the East China Electric Power Design Institute Ministry (ECEPDI) and Beijing CNC specified Energy Recovery PX-220s for YuHuan based on its proven high efficiency and two-year trouble-free track record of the PX-220 installation at the Dalian Petrochemical Plant. The PX Pressure Exchanger® solution created for YuHuan features six trains processing 6,000 m3/day, each with six PX-220s, for a total of 36,000 m3/day.

The Result: 
Significant Energy and Cost Savings Drive Rapid Adoption

Energy Recovery’s YuHuan PX configuration, which has operated since 2006 without issue, achieves real energy transfer efficiencies up to 97% and has cut the energy required for YuHuan’s facility by 68%. Using the PX device has created an economically viable way for China’s residents and industries to benefit from the new electrical power because the PX technology recovers enough energy at YuHuan to reduce power costs by $2.7 million per year. This reduction has cut the carbon footprint of the plant by almost 260 tons of carbon dioxide each year. Because of the success at YuHuan and of the China Petrochemicals Dalian Plant, China leads the world in adoption of efficient PX solutions, with more than 90% of SWRO installations in China using Energy Recovery’s technology.

Chinese island seeks fresh water for residents and tourists

Location: Shengsi, Zhejiang Province, China
Project: Shengsi Municipal Water Company
Capacity: 1,000 m³/ day
Energy Savings: $130,000 or 1.3 million kWh/year*
CO2 savings: 748 tons CO2/year**
* energy savings estimates based on China’s power cost of $0.10/kWh
** based on Energy Recovery’s proprietary Power Model analysis

The Challenge: Island Needs Water for Residents and Tourists

Shengsi, an island in Zhoushan, China’s largest archipelago, is known for its beaches, fishing, and salt production. The area has more than 79,000 residents and hosted more than 2.7 million tourists in 2012, a number that strains the island’s minimal natural water supply. Before constructing a desalination plant, daily water flow and availability could be severely limited especially during drought season. Though expensive, emergency fresh water was sometimes brought by boat (only during good weather), and the inhabitants needed a more reliable source of affordable, clean water. And because power is so costly for the Zhoushan archipelago, the Shengsi Municipal Water Company needed a desalination plant that operated as efficiently as possible.

The Innovation Solution: 
PX Pressure Exchanger

When Hangzhou Torch designed and built a seawater reverse osmosis (SWRO) plant for Shengsi in 2001, the plant included Energy Recovery’s PX® 60 that has now been in operation for more than 60,000 hours (it is one of Energy Recovery’s oldest and longest running PX solutions, operating without maintenance or downtime for more than twelve years). On a second installation, Shengsi Municipal Water tried a competitor’s energy recovery device on a 600 m3/day train but quickly decommissioned it. All subsequent installations at Shengsi’s SWRO plant (1,000 m3/d in 2004, 4,000 m3/d in 2005, and 4,000 m3/d in 2012) have been equipped with Energy Recovery’s PX-140s and PX-220s, all of which operate at full capacity and efficiency. Thanks to unparalleled longevity with the PX, it may be the one part of the SWRO plant that will never need replacement.

The Result: 
Twelve Years of Operation Without Maintenance

A reliable source of clean water in Shengsi has helped the residents, tourists, and island economy. After checkups in 2008 and 2010, Energy Recovery and Shengsi Municipal Water Company were pleased that the maintenance-free, lifetime design of the PX® has yielded virtually no wear to the device, and an estimated $1.5 million savings over its twelve years of operation. Shengsi’s PXs are still operating with maximal efficiency and are recycling 1.3 million kWh per year to keep the cost of water low enough to supply up to 80% of the island’s water needs, and will continue to recapture and recycle fluid-flow energy for the remaining life of the plant.

“The performance of the devices has exceeded our expectations for reliability and energy savings.” – Hangzhou Torch

China’s residents compete for fresh water access

Location: Qingdao, Shandong Province, China
Project: Qingdao BAIFA Seawater Desalination Plant
Capacity: 100,000 m³/day
Energy Savings: US$ 9.6 million or 96 million kWh/year*
CO2 savings: 56,000 tons CO2/year**
* energy savings estimates based on China’s power cost of $0.10/kWh
** based on Energy Recovery’s proprietary Power Model analysis

The Challenge
: Industry Competing with Residents for Access to Fresh Water

In the vibrant seacoast city of Qingdao, China, a diverse population of over 8 million people shares space and resources with rapidly growing industry. The pressing need for a larger municipal water supply led government leaders to commission a seawater reverse osmosis (SWRO) water treatment plant. In choosing Abengoa Water, which has built huge reverse osmosis (RO) plants on other continents, the Municipality of Qingdao sought the expertise of a company that knows how to design and build massive water treatment plants that bring huge quantities of drinking water to urban populations.

The Innovation Solution
: PX Pressure Exchanger 260

Abengoa Water knew from its RO work on several continents that recovering and recycling energy was paramount to keeping water affordable, a consideration especially important given the huge flow capacity needed at Qingdao. Because Energy Recovery’s technological solutions have minimized the cost and energy footprints of their six other mega-projects, Abengoa Water wanted Energy Recovery’s PX Pressure Exchanger® technology to make processing more productive, profitable, and environmentally cleaner.

The Result: 
Drinking Water for Half a Million People

The PX supplied Qingdao’s RO plant with the potential of saving 96 million kWh per year and of cutting 56,000 tons of CO2 emissions with Energy Recovery’s industry-leading technology that recaptures the reusable energy from fluid flows and pressure cycles. The Qingdao processing plant will bring fresh water to up to 500,000 residents of Qingdao. Energy Recovery’s PX trains make desalination more affordable and sustainable by harnessing reusable energy at high efficiency with no downtime. “Abengoa continues to work with Energy Recovery to implement its innovative PX devices to significantly reduce the life cycle costs of the desalination process,” said Carlos Cosín, CEO of Abengoa Water. “We continue to be impressed with the reliability, efficiency and overall performance of its PX technology. We anticipate similar success in the Qingdao facility.”

BVI dependent on reliable fresh water for GDP growth

Location: Tortola Island, British Virgin Islands
Project: Biwater Tortola

Product Configuration: PX Pressure Exchanger and AquaBold high pressure pump

Capacity: 10,400 m³/ day

The Challenge: British Virgin island dependent on reliable freshwater for GDP growth

Tortola is the largest British Virgin island in the Lesser Antilles with an approximate population of 24,000 residents. 92% of its Gross Domestic Product (GDP) comes from tourism where close to one million people visit the island every year. As with many island nations without natural aquifers, Tortola must produce all of its drinking water and demand is constantly high. Historically the island has supplied fresh water to residents and visitors through seawater reverse osmosis desalination, but current facilities in operation are deteriorating and this is having a deleterious effect on the island’s environment and marine life. In order to meet the island’s growing demand for fresh water supply, Biwater was contracted to design a new, environmentally-sound desalination facility to provide high-quality fresh water to the island alongside wastewater treatment facilities.

The Innovation Solution: The PowerPlay for faster time to market with superior energy savings

Biwater selected Energy Recovery’s PowerPlay integrated solution: PX Pressure Exchanger® 220 and the AquaBold high pressure pump. In island nations such as Tortola where power costs are high, Biwater chose the PX energy recovery device because it has the fastest payback than any other ERD in the market and allows the company to focus on delivering the highest quality water at the lowest price to the end user. In summary, by choosing the PX and AquaBold PowerPlay solution, Biwater is able to streamline the complex process of moving the Tortola plant from concept to operation. By combining the PX and the AquaBold, the Biwater Tortola project will enjoy faster deployment, longer life, and greater uptime.

The Result: Highest quality water for island’s biggest industry

The Biwater Tortola plant will be able to supply residents and tourists with highquality, affordable potable water. When operating at full capacity, the Tortola plant will produce 10,400m3 of treated water per day, and with Energy Recovery’s PowerPlay solution, the energy saved will be an estimated 9 million kWh per year – or the equivalent to taking 1,300 cars off the road. In addition to the new desalination facility, Biwater is also providing wastewater treatment facilities that will help better protect marine life in the vicinity. Once the desalination plant is online, the facility will boast the highest efficiencies possible with the Energy Recovery PowerPlay.

Brackish water desalination: energy and cost considerations

Energy recovery devices are employed in nearly all seawater reverse osmosis (SWRO) desalination plants to recover pressure from the membrane reject stream and return it to the process. Because of the high pressures and low membrane permeate recovery rates common in these systems, the membrane reject stream contains a considerable amount of energy. The use of energy recovery devices in seawater RO is readily justified on the basis of operating cost savings. However, the application of energy recovery is much less common in brackish water RO systems, primarily because of the relatively low feed pressure and low flow rate of the membrane reject stream. The fear is that energy recovery devices can also potentially limit the flexibility of a brackish RO process because of efficiency losses or flow-rate constraints encountered during off-peak operation.

White Paper: Permeate recovery rate optimization in Alicante, Spain

Optimization of recovery rate is critical for desalination processes. A high recovery rate gives a high process yield, but requires higher average concentrate salinities in the membrane elements, higher osmotic pressures and higher membrane feed pressures. In addition, supersaturation of the concentrate results in more scaling, and high membrane flux leads to increased fouling. On the other hand, low recovery rate operation directly reduces process yield and can result in excess pretreatment and supply-pumping expenses. Permeate recovery rate optimization, therefore, is a critical exercise for RO process design and operation.