SAN LEANDRO, Calif., Dec 01, 2008 (BUSINESS WIRE) -- Energy Recovery, Inc. ("ERI") (NASDAQ:ERII), a global leader of ultra-high-efficiency energy recovery products and technology for desalination hires a general counsel to head its legal affairs. In her new role, Stanford Law graduate Carolyn Bostick, will join the management team of one of Northern California's fastest growing cleantech companies.


A legal professional with years of global experience, Carolyn Bostick will take charge of the Company's legal activities including intellectual property protection, corporate governance, M&A, compliance and international law related matters. Prior to joining ERI, Carolyn was Vice President and General Counsel of Trend Micro Incorporated, a world leader in content security software based in Japan with offices worldwide. Starting as the company's first full-time attorney in 2000, she developed an international legal team spanning Asia, Europe and Latin America and served as Site Executive for the company's North American Operations. Carolyn started her legal career at Silicon Valley law firms, including Brown and Bain and Heller Ehrman, where she represented companies such as Intel, RSA Data Security, Cargill and ABC Sports in intellectual property and antitrust matters. Carolyn graduated from Brown University and Stanford Law School.


GG Pique, ERI President and CEO stated, "Carolyn is a key addition to our management team. She brings a high level legal expertise to our organization that is critical as we grow. We feel very fortunate to have her as our in-house general counsel."


About ERI(R)


Energy Recovery, Inc. (ERI) is a leading manufacturer of energy recovery devices, which by significantly reducing energy consumption is helping make desalination affordable. ERI's PX Pressure Exchanger(R) technology (PX(R)) is a rotary positive displacement pump that recovers energy from the high pressure waste stream of sea water reverse osmosis systems at up to 98% efficiency with no downtime or scheduled maintenance.


The company has research, development and manufacturing facilities in the San Francisco technology corridor as well as direct sales offices and technical support centers in key desalination hubs such as Madrid, UAE, Shanghai and Florida. ERI service representatives are based in Algeria, Australia, China, India, Korea, Mexico, Taiwan and the Caribbean.


As the demand for clean, potable water increases; ERI is poised to face the global challenges ahead. For more information on ERI and PX technology, please visit www.energyrecovery.com.



SAN LEANDRO, Calif.-- Energy Recovery, Inc. (Nasdaq:ERII), a global leader of ultra-high-efficiency energy recovery products and technology for seawater desalination, announced today that it will release its third quarter results for fiscal 2008 on Tuesday, November 11, 2008, after the market close. The Company will host a conference call for investors on Tuesday, November 11, 2008 at 1:30 p.m. PT.


The conference call will be in a "listen-only" mode for all participants other than the sell-side and buy-side investment professionals who regularly follow the Company. The toll-free phone number for the call is 800-951-9235 or 706-758-9752 and the access code is 68565515. Callers should dial in approximately 15 minutes prior to the scheduled start time. A telephonic replay will be available at 800-642-1687 or 706-645-9291, access code: 68565515, from 5:30 p.m. PT Tuesday, November 11, 2008 to 8:59 p.m. PT on Tuesday, November 24, 2008. Investors may also access the live call or the replay over the internet at www.streetevents.com and www.energyrecovery.com. The replay will be available approximately three hours after the live call concludes.


About ERI(R)


Energy Recovery, Inc. (ERI) is a leading manufacturer of energy recovery devices, which by significantly reducing energy consumption is helping make desalination affordable. ERI's PX Pressure Exchanger(R) technology (PX(R)) is a rotary positive displacement pump that recovers energy from the high pressure waste stream of sea water reverse osmosis systems at up to 98% efficiency with no downtime or scheduled maintenance.


The company has research, development and manufacturing facilities in the San Francisco technology corridor as well as direct sales offices and technical support centers in key desalination hubs such as Madrid, UAE, Shanghai and Florida. ERI service representatives are based in Algeria, Australia, China, India, Korea, Mexico, Taiwan and the Caribbean.


As the demand for clean, potable water increases; ERI is poised to face the global challenges ahead. For more information on ERI and PX technology, please visit www.energyrecovery.com.



Algeria Adds 200,000 m3/day of Increased Seawater Desalination Capacity

SAN LEANDRO, Calif.--(BUSINESS WIRE)--Sept. 24, 2008--Energy Recovery, Inc. ("ERI") (NASDAQ:ERII), a global leader of ultra-high-efficiency energy recovery products and technology for desalination, announced that it had won another large-scale energy recovery contract for seawater reverse osmosis (SWRO) desalination in Algeria. The Mostaganem SWRO Desalination Plant, located approximately 38 miles east of Oran in the western seaside region of the country, will have a total capacity of 200,000 cubic meters per day (m3/day) (52.8 million US gallons per day), enough to supply drinking water to a population of over one million people. The plant is expected to begin operation sometime in the second half of 2009.


The Mostaganem plant is being built on a 25-year build own operate and transfer basis by UTE Mostaganem, a consortium consisting of Inima (Grupo OHL) and Aqualia (Grupo FCC) of Spain. Inima previously selected ERI to provide its advanced energy-saving PX technology for both the 16,000 m3/day Los Cabos and 65,000 m3/day Alicante desalination plants. The Mostaganem project is one of many for ERI in the region, including the 200,000 m3/day Hamma plant built by GE Water and the 200,000 m3/day Beni Saf and 100,000 m3/day Skikda plants currently being built by GEIDA.


The process for the Mostaganem plant will include 240 ERI PX-220 Pressure Exchanger devices arranged in 16 trains of 15 units each. Utilizing PX technology will help significantly reduce power consumption by the plant's high-pressure pumps. Each device will save approximately 80 kilowatts for a total plant energy savings of over 19 mega watts.


Rick Stover, ERI's Chief Technical Officer and Vice President of Sales said, "with this contract, ERI increases its project wins in Algeria to 1,220,000 m3/day of permeate capacity. We are proud to be the energy recovery solution for the region."


About ERI(R)


Energy Recovery, Inc. (ERI) is a leading manufacturer of energy recovery devices, which by significantly reducing energy consumption is helping make desalination affordable. ERI's PX Pressure Exchanger(R) technology (PX(R)) is a rotary positive displacement pump that recovers energy from the high pressure waste stream of sea water reverse osmosis systems at up to 98% efficiency with no downtime or scheduled maintenance.


The company has research, development and manufacturing facilities in the San Francisco technology corridor as well as direct sales offices and technical support centers in key desalination hubs such as Madrid, UAE, Shanghai and Florida. ERI service representatives are based in Algeria, Australia, China, India, Korea, Mexico, Taiwan and the Caribbean.


As the demand for clean, potable water increases; ERI is poised to face the global challenges ahead. For more information on ERI and PX technology, please visit www.energyrecovery.com.



140,000 m3/day (37MGD) Desalination Project for Mining Application Contracted to use PX(R) Technology


SAN LEANDRO, Calif., Oct. 2 /PRNewswire-FirstCall/ -- Energy Recovery, Inc. ("ERI") (Nasdaq: ERII), a global leader of ultra-high-efficiency energy recovery products and technology for desalination, announced that it will supply energy recovery devices for a seawater reverse osmosis (SWRO) desalination project in Australia. IDE Technologies awarded ERI the energy recovery contract for the 140,000 cubic meters per day (m3/day) (37 million gallons per day (MGD)) facility. The new desalination project adds process and drinking water for a large mine operation in Australia.


IDE Technologies will construct the plant which will utilize ERI's PX Pressure Exchanger(R) (PX(R)) technology as the energy recovery solution for the project. The plant is scheduled for completion in late 2009.


Water is a key component in the mining process. Because the region is subject to extreme drought conditions, a highly efficient desalination system provides an affordable solution both for process requirements and regional drinking consumption. The ERI solution will include PX-220 devices which will save an estimated 16 megawatts of power.


In 2007, ERI was also engaged for a 55,000 m3/day (14.5 MGD) desalination plant for the Trekkopje Uranium project in Namibia, South Africa. That plant is projected to supply an estimated 20 million cubic meters of water per year to the mine. In addition, ERI and IDE Technologies are teaming to provide advanced energy-saving PX technology for the 100 million m3/year Hadera, Israel desalination plant which will be the world's largest such plant when it starts up in 2010.


About ERI(R)


Energy Recovery, Inc. (ERI) is a leading manufacturer of energy recovery devices, which by significantly reducing energy consumption is helping make desalination affordable. ERI's PX Pressure Exchanger(R) technology (PX(R)) is a rotary positive displacement pump that recovers energy from the high pressure waste stream of sea water reverse osmosis systems at up to 98% efficiency with no downtime or scheduled maintenance.


The company has research, development and manufacturing facilities in the San Francisco technology corridor as well as direct sales offices and technical support centers in key desalination hubs such as Madrid, UAE, Shanghai and Florida. ERI service representatives are based in Algeria, Australia, China, India, Korea, Mexico, Taiwan and the Caribbean.


As the demand for clean, potable water increases; ERI is poised to face the global challenges ahead. For more information on ERI and PX technology, please visit www.energyrecovery.com.


The sand screens and micron filters were selected because of the durable and corrosion resistant fiberglass and PVC construction. The specific model of Eden micron filters was chosen to maintain the filter element flux at approximately 3.3 gpm/per 10" equivalent.


Due to the relative remoteness of the installation site, multistage-centrifugal, high-pressure pumps have been selected for their reliability, availability of parts, economics of operation and easy maintenance. Centrifugal pumps in general are smoother, quieter, and require less ancillary equipment (i.e. pulsation dampeners) than positive displacement pumps. Hydropro has found that positive displacement pumps are much more prone to failure and lengthily downtimes than high-quality centrifugal pumps.


The Grundfos Booster Modules were chosen for several reasons. The inline style helped conserve space and provided ease of installation, allowing everything to be mounted on the same skid (with the exception of cleaning/flush tanks, raw water booster pumps, and chemical feeds). These submersible, multi-stage centrifugal pumps were also chosen because they are very efficient and quiet, and are constructed of corrosion resistant, 904L super austenitic stainless steel.


The high pressure feed and concentrate headers were made of 2205 duplex stainless steel for superior corrosion resistance, and the structural skid was constructed of FRP for low weight and zero maintenance. ERI´s Pressure Exchanger was chosen because of its high energy efficiency, dependability, and corrosion resistant materials.


Performance


Values for the projected power consumption rates that were presented in the proposal were based on a 27ºC feed stream of 45,000 mg/l TDS and a permeate flow rate of 100,000 gpd. The membrane manufactures projection software was used to determine the system parameters at a recovery of 35%, and these parameters were subsequently used to determine the projected power consumption. The result was an anticipated feed pressure of 900 psi and a specific power consumption rate of 3.02 kWh/m³.


Once the system was installed and operating, the specific power consumption was calculated based on actual system parameters and the result was a much lower value of 2.65 kWh/m³. There were several reasons the actual value was lower, the main reason however, was the conservative design. Because of some uncertainty in the feed water quality, the SWRO system was designed with a relatively low flux (approximately 8 gpm/ft2), and a somewhat large hydraulic envelope. As it turned out, the feed water TDS was closer to 36,000 ppm and fairly stable. The lower feed TDS enabled the system to operate at a lower membrane feed pressure of 790 psi and a higher permeate flow rate of 120,000 gpd, consequently using less energy than originally projected and making higher quality permeate.


Conclusion


With most of the system assembled, the installation was fairly straightforward and went smoothly. The two units were installed, started up, tested and operator training was completed in less than three weeks. There was, however, a problem with the feed water quality and the pretreatment system, which was discovered after only 24 hours of operation. It immediately became apparent that the raw water was loaded with particulate that was quickly fouling the sand screens and the micron filters. Fortunately, the feed system could be modified to flow into an existing 250,000 gallon seawater tank from the wells, and the SWRO feed was then drawn out of this tank. This settling tank solution worked quite well and provided a feed water with a pre-filter SDI of 1.25.


There was also one other performance issue that needed to be resolved. Initially, the permeate quality was less than what was projected, and it was not clear why. The system was extensively checked ant tested for leaks, and the possibility that seawater was somehow mixing with the permeate was eventually eliminated. It was finally determined that the membranes did not meet the design rejection required to produce the projected permeate TDS. Once the membranes were replaced, the system was making plenty of high quality permeate that was well below the maximum acceptable permeate TDS.


KAJUR and the residents of Ebye have since been enjoying low-cost, high-quality water for over a year now without any noteworthy system failures. They are so pleased, in fact, that KAJUR has recently awarded Hydropro another SWRO job utilizing work exchanger energy recovery.



Design Requirements


Traditionally Hydropro has always put the needs of the customer into the forefront of its company philosophy. By doing this, Hydropro has always stayed abreast of the latest advancements in technology in the water treatment field. In this case, mostly because of the remote location (nearly everything, including fuel for the diesel generators, is delivered by ship), the most important customer needs were associated with conserving energy and maintaining reliability. Availability of replacement parts was also a major concern due to the remote location and the lead-time required to ship items to the island. Another concern Hydropro had to address was ease of operation and ease of maintenance, as the remote island of Ebye did not have any skilled RO plant operators. The end result would incorporate all these requirements to produce a reliable supply of potable water from a seawater source for the citizens of Ebye.

In the original RFP, KAJUR requested twin 75,000 gpd SWRO units (expandable to 100,000 gpd) designed for a seawater feed of 45,000 mg/l TDS. The proposal presented by Hydropro was for two Seawater Reverse Osmosis Water Treatment units each designed to produce 75,000 gallons per day. Permeate water was projected to be of less than 300 mg/l TDS based on feed water from seawater wells with a maximum TDS of 50,000 mg/l and an SDI of less than 3. Each unit was designed to be easily expandable to a daily capacity of 100,000 gallons by the addition of one pressure vessel containing seven seawater membranes. All instrumentation, piping, valves, headers and pumps were pre-sized to accommodate the expansion.


Each proposed SWRO system consisted of four pressure vessels containing seven membrane elements each arranged in a single, one-pass array. With the expansion, the system would consist of five pressure vessels in a single staged array. Each system was designed to operate at a 30-40% recovery rate, with a maximum trans-membrane (feed to product) pressure of 1100 psi at a feed water TDS of 50,000 mg/l. With a feed water TDS of 46,000 mg/l, the trans-membrane pressure was projected to be approximately 900 psi at startup and 950 psi after three years of operation.


System Design


The final, installed 100,000 gpd Hydropro design consisted of the following major components and unit operations for each SWRO unit:
• Sand and Particulate Filters: Two HYDROPRO Tubular filter units Model STF5M2-400- PVC/150 each consisting of one PVC housing with a 150-micron wedge wire PVC screen for the removal of sand and particles, with automatic purge valves
• Micron Filters: Three heavy-duty filter housings constructed of FRP/PVC and built to ASME Code X, the housings are Eden Model 24EFC each accommodating six (6) 40" long five micron polypropylene cartridges
• RO High Pressure Booster Pumps: Two high pressure feed booster pumps Grundfos Model BM 17-27R (installed in series) - horizontal centrifugal, multi-stage construction of 904L Super Austenitic Stainless Steel, each driven by a 35 HP submersible type motor rated at 460V/60Hz/3Ø utilizing a Soft start motor starter and VFD RO Low Pressure Booster Pump: One booster pump Grundfos Model BM 30-4R - horizontal centrifugal, multi-stage type of 904L Super Austenitic Stainless Steel, driven by a 7.5 HP submersible type motor rated at 460V/60Hz/3Ø controlled by a variable frequency drive
• Membrane Modules: One FRP construction structural frame, five pressure vessels of FRP construction rated at 1200 psi operating pressure, 35 Thin Film Composite membrane elements ¬ 8" x 40", 2205 DUPLEX SS headers for feed and concentrate and Sch. 80 PVC for the permeate headers and low pressure feed, suction and concentrate piping, Allen- Bradley PLC SLC 5/04 based control system - installed in a NEMA 4X enclosure with system switches lights etc. installed on the panel door
• Chemical Feed Systems: One anti-scalant dosing system and one chlorine dosing system
• Freshwater Flush/Membrane Cleaning System


The system skid was designed and fabricated for a compact footprint due to limited installation space and to allow for shipping both units in a single container. The entire system was pre-assembled as much as possible to minimize field services.



Conventional Design


Previously, the standard Hydropro design for SWRO with energy recovery incorporated a single multistage centrifugal pump (or positive displacement) with a Hydraulic Turbo Booster. This design is fairly simple and generally does not require a significant increase in system controls or instrumentation and is for the most part a sound, and energy efficient SWRO design.


The hydraulic turbo booster converts the hydraulic energy of the concentrate stream to mechanical energy and then applies this mechanical energy to the full flow of the feed stream in the form of a considerable pressure boost. In a single stage SWRO system, the energy benefit associated with this type of energy recovery device is realized solely in the form of lower pressure (and thus lower horsepower) requirements for the high pressure feed pump. Because the equations used to predict the pressure boost produced by a HTB are usually specific to the manufacturer and dependent upon the system parameters, they will not be explicitly discussed here. In this case, a reasonable assumption would be a 300 psi (693 feet H2O) pressure boost from the HTB operating in a system as described in Example 1 below. The following example is used to demonstrate the reduction in high pressure feed pump horsepower requirements:


This HTB energy recovery device provides a substantial reduction in specific energy consumption, which, depending on the duty cycle and cost of power could pay for itself in a relatively short amount of time.


New Technology


The concept of a work exchanger energy recovery device was certainly not new, and several variations of these devices have come and gone. However, at the time of this proposal, there seemed to be a new approach to the design of these positive displacement devices that eliminated many of the problems associated with previous versions. The PE from Energy Recovery, Inc. (ERI) is an example of a novel work exchanger device that was in a position to profoundly affect the design of SWRO and the energy recovery industry.


The main idea of the Pressure Exchanger is its ability to directly transfer most of the hydraulic energy in the concentrate stream to an equal amount of feed water. The result is a side feed stream equal in flow to the concentrate stream (minus bearing leakage) that is boosted to near membrane feed pressure by the Pressure Exchanger. A small high pressure booster pump is then required to boost the high pressure feed exiting the PE so that it equals the discharge pressure of the high pressure feed pump and the two feed streams can be combined. This pressure boost accounts for pressure losses associated with inefficiencies of the pressure exchanger, losses across the membranes, and piping and fitting losses throughout the system. By significantly reducing the size of the high pressure feed pump to approximate the flow of permeate, the horsepower of the high pressure pump can be reduced by approximately two thirds of the total pumping power required. This substantial reduction in horsepower is, for the most part, specific to the high pressure, low recovery nature of the SWRO system. To illustrate the effect of this reduction in pumping power required, the following example is used:


Although there are other energy considerations besides just pumping power when comparing a system with no energy recovery and a system with a PE, this simple analysis shows a significant reduction in energy consumption when using a Pressure Exchanger.


Water-short California's search to satisfy its thirst is beginning to focus on a controversial source -- the Pacific Ocean.


In November, Connecticut-based Poseidon Resources Corp. won a key regulatory approval to build a $300 million water-desalination plant in Carlsbad, north of San Diego. The facility would be the largest in the Western Hemisphere, producing 50 million gallons of drinking water a day, enough to supply about 100,000 homes.


Taking the salt out of seawater is a common way to produce drinking water in the Middle East and in other arid regions. World-wide, 13,080 desalination plants produce more than 12 billion gallons of water a day, according to the International Desalination Association.


But it has been less successful in the U.S. Desalination is more expensive than traditional sources, and critics say it harms the ocean. In 1992, Santa Barbara, Calif., shuttered a small plant after three months when rain replenished the county's main water sources. At a plant near Tampa, Fla., that Poseidon was also involved in, technical glitches increased the water's cost and, when it opened in 2003, initially limited output to less than a third of the projected 25 million gallons a day.


Southern California water officials say conditions have changed. Improved technology has cut the cost of desalination in half in the past decade, making it more competitive. And traditional water supplies, such as the Colorado River and snow-melt runoff, are becoming less reliable because of population growth and environmental restrictions.


"We have to get our water from somewhere, and it's going to be the Pacific Ocean," says Gary Arant, manager of the Valley Center Municipal Water District, which serves farms and homes around San Diego. His district has agreed to buy almost 15% of the Carlsbad plant's output. Poseidon says it has signed 30-year contracts with nine local water districts to sell all the water; about 40% would go to the city of Carlsbad.


The project has attracted big financial partners. In May, General Electric Co. said it had invested in it and would provide filtration technology. In September, Citigroup Inc.'s sustainable-development-investments unit became the lead investor in closely held Poseidon, formed in 1995 by former GE executives and private-equity firm Warburg Pincus. Andrew de Pass, the Citigroup unit's managing director, says the need for long-term water sources drove the investment. He declined to specify how much Citigroup invested.


Poseidon hopes to break ground this year and deliver water no later than 2011, providing it wins approval for its plans to mitigate the plant's impact on marine life and to offset its carbon-dioxide emissions.


The plant would initially take the saltwater discharged from an adjacent power plant that uses it for cooling, and later take water directly from the Pacific. Two sets of filters purify the water. The first set, thin tubes resembling rows of angel-hair pasta, blocks relatively large particles. The seawater is then pumped at very high pressure through dense membranes to remove salt, in a process called reverse osmosis.


This process uses a lot of electricity, contributing to its big price tag. Poseidon plans to sell the water for about $950 per acre-foot. That compares with an average $700 an acre-foot that local agencies now pay for water. (An acre-foot is 325,851 gallons, enough water for four people a year.) The Metropolitan Water District, a wholesale supplier to 18 million Southern Californians, will subsidize the difference as a way to add new water sources to the region. Poseidon President Walter Winrow says Poseidon will raise its price as local agencies pay more for water from other sources.


Peter Gleick, head of environmental think-tank Pacific Institute, says the costs of desalination projects tend to increase from those projected by sponsors, because of energy expenses and environmental requirements. "What people claim is always a little different," says Mr. Gleick.


There are other obstacles. California coastal regulators and some environmentalists say desalination uses too much energy and kills fish when the water is processed. Two environmental groups Monday filed suit to block the plant, on the grounds that it will harm marine life. Peter MacLaggan, who oversees the Carlsbad project for Poseidon, says the plant would kill about two pounds of fish a day, or "less than the daily consumption of one pelican."


Some opponents are wary of Poseidon because it was originally the co-developer of the troubled Tampa plant. Poseidon and the engineering firm it was working with estimated in 1999 that the plant would cost $110 million to build and produce water costing an average of $677 an acre-foot.


Then two engineering firms involved in the plant ran into financial difficulties, slowing work on the project.


In 2002, Tampa Bay Water, the government agency building the plant, bought out Poseidon and took on plant oversight. Tampa Bay Water ultimately brought in other companies, including units of Spain's Acciona S.A. and Germany's RWE AG, to finish and run the plant.


Last month, years behind schedule, the plant was declared fully operational, producing more than 25 million gallons of drinking water a day. Exceeding the initial estimate, construction came to $158 million, and the desalinated water costs $1,100 an acre-foot. Tom Pankratz, a Houston-based consultant to Tampa Bay Water's lawyers and a spokesman for the IDA, says there was "sloppy work" across the board. Poseidon's president, Mr. Winrow, says the company "would have managed the construction more appropriately" if it had been allowed to finish the project.


Ken Herd, Tampa Bay Water's operations director, says the plant is mostly running smoothly and the region may build more plants. Desalination is "not the cheapest source of supply, but it's drought-proof," he says.


Southern California officials toured the Tampa Bay plant before signing with Poseidon on the Carlsbad plant. Poseidon has brought in Acciona and RWE'S American Water to design and operate it.


Meanwhile, improved membranes and pumping systems have sharply reduced electricity costs. G.G. Pique, chief executive of Energy Recovery Inc., which makes desalination technology for the plant, estimates it will cost the Carlsbad plant $1.10 in electricity to produce 1,000 gallons of water. That is down from $2.10 per 1,000 gallons at the mothballed Santa Barbara plant, which he was also involved in.


The push on the Carlsbad plant comes as the National Academy of Sciences nears completion of a report on the potential role of desalination in meeting U.S. water needs.


Water experts are watching closely. California regulators are mulling as many as 20 proposed seawater projects that could produce 500 million gallons of water a day for the state. Poseidon is planning a second major plant in Huntington Beach, about 60 miles north of Carlsbad. "We're excited about the prospects," says Mike Chrisman, California's Secretary of Water Resources.



Tampa, FL, September 16, 2008 - The Ministry of Electricity and Water (MEW) of Kuwait awarded Doosan Heavy Industries & Construction the 136,000 m3/day (36 million US gallons per day (MGD)) Shuwaikh Seawater RO Desalination Plant with Recarbonation system. Doosan Heavy Industries & Construction is executing the project on an EPC basis while Doosan Hydro Technology, the wholly owned US based subsidiary, will partially provide basic process design engineering, as well as detail engineering review services. Energy Recovery, Inc. (“ERI”) (NASDAQ:ERII), a global leader of ultra-high-efficiency energy recovery products and technology for desalination was also contracted for its innovative PX Pressure Exchanger (PX) technology for the Shuwaikh SWRO project.


Water sustainability is a growing concern in the Middle East and the Kuwaiti Ministry of Electricity and Water has taken proper measures to sustain a potable water supply for its communities. The Plant is Kuwait’s first seawater desalination plant using RO technology. It will supply drinking water for 450,000 residents in Kuwait City. Under the contract, Doosan will design and build the plant, which is to be built near Shuwaikh port, as well as supply equipment and materials. The project is scheduled for completion in September 2010.


Doosan selected ERI’s largest commercially available 65-Series product, the PX-260 energy recovery device due to its high efficiency, flexibility and small footprint. The project will include 187 PX-260 PX Pressure Exchanger® energy recovery devices which will save an estimated 12.7 megawatts of power. ERI and Doosan also teamed up for the 150,000 m3/day (39.6 MGD) Al Shuaibah III Expansion SWRO Desalination Plant in September of 2007.


Dr. Richard Stover, ERI Chief Technology Officer stated, “We are excited about winning this project in Kuwait. Our ground-breaking work in the early 1990’s at the Kuwait Institute of Scientific Research (KISR) Laboratories laid the foundation for our innovative PX technology. It’s with great pleasure that we are able to give back to the region”, Dr. Stover continued. ERI has several desalination plants throughout the Middle East and North Africa engaging its PX technology. From large plants in Algeria and the UAE to smaller plants throughout Egypt and Saudi Arabia; ERI has focused its efforts on providing the region with advanced energy recovery solutions. The company has a regional sales office in Dubai.


About ERI(R)


Energy Recovery, Inc. (ERI) is a leading manufacturer of energy recovery devices, which by significantly reducing energy consumption is helping make desalination affordable. ERI's PX Pressure Exchanger(R) technology (PX(R)) is a rotary positive displacement pump that recovers energy from the high pressure waste stream of sea water reverse osmosis systems at up to 98% efficiency with no downtime or scheduled maintenance.


The company has research, development and manufacturing facilities in the San Francisco technology corridor as well as direct sales offices and technical support centers in key desalination hubs such as Madrid, UAE, Shanghai and Florida. ERI service representatives are based in Algeria, Australia, China, India, Korea, Mexico, Taiwan and the Caribbean.


As the demand for clean, potable water increases; ERI is poised to face the global challenges ahead. For more information on ERI and PX technology, please visit www.energyrecovery.com.


SAN LEANDRO, Calif., Sep 09, 2008 (BUSINESS WIRE) -- Energy Recovery, Inc. ("ERI") (NASDAQ:ERII), a global leader of ultra-high-efficiency energy recovery products and technology for desalination, announced that the company recruited seasoned water treatment applications veteran and membrane housing expert Douglas Eisberg to be the company's Product Director.


As Product Director, Doug's responsibilities include identifying new applications for PX technology, promoting PX technology for brackish water desalination applications and assisting with the development of future PX device and pump designs. He will also help develop strategic collaborative relationships throughout the industry.


Prior to joining ERI, Doug worked for 17 years at Advanced Structures Inc., the makers of CodeLine (Pentair Water) pressure vessels, where he managed the development, engineering and sales departments. He was instrumental in the design of many composite membrane housing features now considered industry standards and holds several related international patents. In addition, Doug was the founder and President of PROTEC (Bekaert Progressive Composites) membrane pressure vessels.


Doug serves as the Chairman of the American Society of Mechanical Engineers (ASME), Boiler and Pressure Vessel Code Section X Subcommittee. He is also a Director in the American Membrane Technology Association (AMTA) and has served as the Chairman of the Nomination Committee. In addition, Doug is a board member of the International Desalination Association (IDA) as the Liaison for AMTA.


Dr. Richard Stover, ERI CTO said "As one of the most accomplished and best known figures in desalination, we are proud to have Doug join our team. His lifetime experience in the water industry coupled with his creative and analytical capabilities will be important contributions to ERI's strategic growth initiatives."


About ERI(R)


Energy Recovery, Inc. (ERI) is a leading manufacturer of energy recovery devices, which by significantly reducing energy consumption is helping make desalination affordable. ERI's PX Pressure Exchanger(R) technology (PX(R)) is a rotary positive displacement pump that recovers energy from the high pressure waste stream of sea water reverse osmosis systems at up to 98% efficiency with no downtime or scheduled maintenance.


The company has research, development and manufacturing facilities in the San Francisco technology corridor as well as direct sales offices and technical support centers in key desalination hubs such as Madrid, UAE, Shanghai and Florida. ERI service representatives are based in Algeria, Australia, China, India, Korea, Mexico, Taiwan and the Caribbean.


As the demand for clean, potable water increases; ERI is poised to face the global challenges ahead. For more information on ERI and PX technology, please visit www.energyrecovery.com.


SAN LEANDRO, Calif.--(BUSINESS WIRE)--Sept. 3, 2008--Energy Recovery, Inc. ("ERI") (NASDAQ:ERII), a global leader of ultra-high-efficiency energy recovery products and technology for desalination, announces that the Spanish joint venture of FCC / AQUALIA / BEFESA group of companies awarded the contract for energy recovery equipment for its Bajo Almanzora seawater desalination project to ERI. The plant will supply 60,000 m3/day (15.9 MGD) of fresh water to the region.


The design, build and operate seawater desalination project was awarded to the partnership of FCC/AQUALIA and BEFESA in August 2007 by Acuamed, the Spanish governmental water authority. Spanish companies have played a leadership role in designing and building desalination plants world-wide. The plant is located in the province of Almeria, Andalucia region, along the southeastern border of Spain. It is currently under construction and is scheduled to produce water in 2009. The Bajo Almanzora seawater desalination plant will supply water to one of the warmest provinces in the country where the level of rainfall is one of the lowest in Europe, with much of the area containing semi-arid and desert-like landscapes.


ERI PX(R) technology was specified for the project. ERI will supply 50 PX-220 energy recovery devices to operate in the first-stage of the reverse osmosis process. It is estimated that this technology will save the project over 5 mega-watts of high-pressure pump power. Last year, Befesa and ERI teamed to provide and energy recovery solution to India's largest desalination plant located in Chennai.


ERI's Vice President, of the Mega Projects Division stated, "As with all our projects, we feel very satisfied when our customers build desalination plants that consider energy recovery as a key component of the overall solution."


About ERI(R)


Energy Recovery, Inc. (ERI) is a leading manufacturer of energy recovery devices, which by significantly reducing energy consumption is helping make desalination affordable. ERI's PX Pressure Exchanger(R) technology (PX(R)) is a rotary positive displacement pump that recovers energy from the high pressure waste stream of sea water reverse osmosis systems at up to 98% efficiency with no downtime or scheduled maintenance.


The company has research, development and manufacturing facilities in the San Francisco technology corridor as well as direct sales offices and technical support centers in key desalination hubs such as Madrid, UAE, Shanghai and Florida. ERI service representatives are based in Algeria, Australia, China, India, Korea, Mexico, Taiwan and the Caribbean.


As the demand for clean, potable water increases; ERI is poised to face the global challenges ahead. For more information on ERI and PX technology, please visit www.energyrecovery.com.

91,000 m3/day (24 million gallons per day) Hamriyah Seawater


Desalination Plant in Sharjah Selects PX Technology


SAN LEANDRO, Calif.--(BUSINESS WIRE)--Aug. 5, 2008--Energy Recovery, Inc. ("ERI") (NASDAQ:ERII), a global leader of ultra-high-efficiency energy recovery products and technology for desalination, announced that it has been awarded a contract to provide the energy recovery technology for the Hamriyah (Phase 1) Power Station Seawater Reverse Osmosis (SWRO) Desalination Plant. Aqua Engineering GmbH and ERI have signed a supply agreement for PX(R) energy recovery devices for the 91,000 cubic meters per day (m3/day) (24 million gallons per day (MGD)) plant to be located in Sharjah, United Arab Emirates.


The plant was awarded to Austrian company Aqua Engineering GmbH, a subsidiary of Christ Water Technology AG, by the Sharjah Electricity and Water Authority (SEWA). The overall capacity of the Hamriyah facility will be 455,000 m3/day (120 MGD) of fresh water by reverse osmosis technology and 181,000 m3/day (48 MGD) by a thermal desalination process called multiple effect distillation (MED). This phase of the project will include 104 PX-260 PX Pressure Exchanger(R) energy recovery devices which will save an estimated 13 megawatts of power. Designed with a total of eight (8) SWRO trains operating in parallel, the devices will provide fail-safe redundancy and reliability with little or no down-time. Currently, the plant is under construction and scheduled for start-up in 2009. Initial work on the site included a 600 MW power plant. The SEWA project will eventually supply 2000 MW of power and 637,000 m3/day (168 MGD) of desalinated water.


In late 2007, ERI announced the release of its PX-260 device, the latest addition to its PX technology line of products. The PX-260 is part of the 65-Series product line and is the Company's largest commercially available energy recovery device, handling brine flow rates of up to 260 gallons per minute (59 cubic meters per hour) - nearly 20% greater capacity than ERI's former largest device. It operates at the highest efficiency, providing the best overall energy savings and lowest cost of ownership of any commercially available energy recovery solution.


The Middle East has been a mainstay for ERI with many small to large plant installations across the region, ranging from small hotels in Egypt and UAE to larger projects in Saudi Arabia, among others. The company has a regional sales office in Dubai.


"This is the fourth plant within a few years for which we have chosen PX technology. Having installed them in various plant sizes in Oman and UAE, we found these devices working very reliably and most efficiently," stated Guido Codemo, Process Engineer for Aqua Engineering.


About ERI(R)


Energy Recovery, Inc. (ERI) is a leading manufacturer of energy recovery devices, which by significantly reducing energy consumption is helping make desalination affordable. ERI's PX Pressure Exchanger(R) technology (PX(R)) is a rotary positive displacement pump that recovers energy from the high pressure waste stream of sea water reverse osmosis systems at up to 98% efficiency with no downtime or scheduled maintenance.


The company has research, development and manufacturing facilities in the San Francisco technology corridor as well as direct sales offices and technical support centers in key desalination hubs such as Madrid, UAE, Shanghai and Florida. ERI service representatives are based in Algeria, Australia, China, India, Korea, Mexico, Taiwan and the Caribbean.


As the demand for clean, potable water increases; ERI is poised to face the global challenges ahead. For more information on ERI and PX technology, please visit www.energyrecovery.com.

ABSTRACT

The new pressure exchanger (PX) device transfers the energy from the concentrate stream directly to the feed stream. This direct, positive displacement approach results in a net transfer efficiency of over 95%. Although application of the PX technology is simple in both theory and practice, in order to get the most benefit from this technology it is important to reconsider the SWRO design and operation approach. Pertinent design considerations include pre-filtration, conversion rate optimization; pump selection, and operating pressures. Some important operating procedures and characteristics are start up, high pressure regulation, conversion rate optimization, flow balancing, and shutdown. Furthermore, it will be shown that these considerations affect the design and operation of SWRO systems counter-intuitively and may possibly reverse given standards that have been developed over the past 20 years of SWRO design.

There has been a recent proliferation of commercially available energy recovery devices based on the positive displacement direct pressure exchange approach. This increased interest is driven by the fact that the technology can reduce the energy consumption of an SWRO system by as much as 60%. Since energy costs are rising and can consume as much as 75% of the total operating costs of an SWRO plant, it is important that the technology be encouraged and disseminated throughout the industry. Although the authors of this paper are directly associated with Energy Recovery, Inc., a leading company in pressure exchanger technology, the principles and theories presented in this paper will be applicable to all devices based on the positive displacement, direct pressure exchange approach.

4.0 START AND STOP PROCEDURES
Starting and stopping an SWRO system designed around the PX pressure exchanger device is actually simpler than with systems designed around other technologies such as regulating valves, turbos and Pelton wheels. This is because of the self-balancing nature of SWRO systems designed around pressure exchanger technologies.

4.2 System start up sequence

Start up of an SWRO plant designed around the PX device is very simple. The first step is to start the raw water supply pump. At this point the system will begin to fill with water and the PX may or may not start to spin. Next, start the high-pressure boost pump. The associated pressure drops through the RO membranes and PX combine with the high-pressure boost pump curve to dictate the reject flow rate into and seawater flow rate out of the PX unit. This means that once the high-pressure boost pump is running and has stabilized the reject flow is now running at or very near the normal flow rate for the plant. Now it is time to start the main high-pressure pump, which will pressurize the RO system. The system will reach the exact pressure required to produce the amount of product water being injected to the RO system by the main high-pressure pump. The membranes create the back-pressure in the system and now act like the pressure-regulating valve. It will take 5-10 seconds for a typical system to pressurize once the main high-pressure pump is started. It may be advisable to install a high-pressure bypass valve at the outlet of the RO membranes that can be closed slowly at start up. This will allow the operator to control of the rate at which the RO system reaches full operating pressure.

4.3 SYSTEM SHUT DOWN SEQUENCE

First stop the main high-pressure pump. After approximately 30 seconds the pressure in the RO system will drop to around 27 bar. At this point it is proper to stop the high-pressure booster pump and raw water supply pump. It should be noted that because the high-pressure side of the PX is sealed from the low pressure side of the PX the high pressure RO portion of the plant can maintain significant pressure for an extended period of time.

4.4 Fresh water flush

If the SWRO system is going to be shut down for an extended period of time it is required to fresh water flush the RO membranes and pressure exchanger in order to inhibit biological growth and fouling. Start by supply the RO system with un-chlorinated fresh water at the normal system feed pressure. Next run the high-pressure booster pump until all of the seawater has been purged from the RO membranes. It may also be desirable to also run the high-pressure pump for a few seconds during this process to ensure that it gets a complete flush as well.

5.0 FLOW CONTROL AND BALANCING THE SYSTEM

Flow rates and pressures in a SWRO plant will vary slightly over the life of a plant. Variations may be due to temperature, membrane fouling, seasonal feed salinity variations, etc. The following designs and procedures should be used to control these variables.

5.1 High Pressure Reject and Seawater Feed Flow Control

In order to control the high-pressure reject and feed flow rates, adjustment of the pressure and flow supplied by the high-pressure booster pump is typically required. Recommended practice is to use a high pressure booster pump with some additional capacity, and control its flow and pressure with a variable frequency drive or control valve. A high-pressure flow meter can be used to determine the amount of reject and feed water flowing through the high-pressure side of the pressure exchanger device. Remember that the high-pressure reject water and feed water are hydraulically connected and are separated only by a water barrier/piston. It is also possible to infer the high-pressure flow rates from the pressure drops across the pressure exchanger and/or high-pressure boost pump. Increasing and decreasing these flow rates is how we decrease and increase respectively the conversion rate of the RO system independently of the product water being produced.

5.2 Low Pressure Reject and Seawater Feed Flow Control

In order to control the flow rates of the low-pressure feed and reject water, adjustments to the low pressure seawater inlet pressure to the PX should be made. Recommended practice is to install a valve at the low-pressure seawater inlet of the PX unit(s). Remember that the low-pressure seawater and reject water are hydraulically connected and are separated only by a water barrier/piston. The low pressure seawater and reject flow rates can be determined by installing a flow meter at the low-pressure seawater inlet of the PX.

5.3 Balancing the pressure exchanger using flow meters

All flows in and out of the Pressure Exchanger must be approximately balanced. The following equation applies to this process:
High pressure seawater outlet flow = Low pressure seawater inlet flow
Determine the desired amount of high-pressure seawater outlet flow, which is approximately equal to the reject flow for your system. Adjust the variable frequency drive or control valve on the high pressure booster pump until that flow rate is achieved as seen at the high-pressure flow meter. In the absence of a high-pressure flow meter it is also possible to infer the flow rates from the pressure drops across the boost pump and/or pressure exchanger(s).

Adjust the low-pressure seawater inlet valve until the low-pressure seawater inlet flow equals the high pressure seawater outlet flow.
If the low pressure seawater inlet flow is less than the high pressure seawater outlet flow excessive intermixing of reject with the feed will occur which will result in lower quality permeate, increased feed pressure and higher energy consumption. If the low-pressure seawater inlet flow is greater than the high-pressure seawater outlet flow, treated feed water is being wasted and dumped to the low-pressure reject drain.

6.0 CONCLUSION

The PX is a new pressure exchanger device that promises to revolutionize SWRO design. The device affects the design and operation of SWRO systems in several counter-intuitive ways. As we have discussed, lower conversions rates in the order of 30-40% actually yield lower energy profiles than higher conversion rates. Furthermore, these systems operate at lower pressures and produce better water quality.
The fact that the main high pressure pump flow equals the permeate flow means that we can now achieve SWRO systems with nearly 100% conversion rates when considering the pumping power that is being applied. This fact also means that for any given high pressure pump, systems that are 2-3 times larger can be achieved with that same pump.

The PX device now makes it possible to adjust the conversion rate of an SWRO plant independently of product water production. This means that the conversion rate can now be simply and directly used to optimize the efficiency of the RO membranes rather than having to balance it against energy consumption, product quality, membrane pressure limits, and so on.

It is clear that this device is an extremely efficient approach to energy recovery, and that the SWRO systems of today and the future will consume far less energy than those of yesterday. However, the impact that this device will have on design concerns such as the conversion rate, water quality, and operating pressures will surely surprise us all.

ABSTRACT

The new pressure exchanger (PX) device transfers the energy from the concentrate stream directly to the feed stream. This direct, positive displacement approach results in a net transfer efficiency of over 95%. Although application of the PX technology is simple in both theory and practice, in order to get the most benefit from this technology it is important to reconsider the SWRO design and operation approach. Pertinent design considerations include pre-filtration, conversion rate optimization; pump selection, and operating pressures. Some important operating procedures and characteristics are start up, high pressure regulation, conversion rate optimization, flow balancing, and shutdown. Furthermore, it will be shown that these considerations affect the design and operation of SWRO systems counter-intuitively and may possibly reverse given standards that have been developed over the past 20 years of SWRO design.

There has been a recent proliferation of commercially available energy recovery devices based on the positive displacement direct pressure exchange approach. This increased interest is driven by the fact that the technology can reduce the energy consumption of an SWRO system by as much as 60%. Since energy costs are rising and can consume as much as 75% of the total operating costs of an SWRO plant, it is important that the technology be encouraged and disseminated throughout the industry. Although the authors of this paper are directly associated with Energy Recovery, Inc., a leading company in pressure exchanger technology, the principles and theories presented in this paper will be applicable to all devices based on the positive displacement, direct pressure exchange approach.

1.0 INTRODUCTION

The PX is a new pressure exchanger device that transfers the energy from the concentrate/reject stream directly to the feed stream in a cylindrical rotor with longitudinal ducts. The rotor spins inside a sleeve between two end covers that divide the rotor into high and low pressure halves. When designing a seawater RO system using the new pressure exchanger device it is only necessary to reconsider the high pressure portion of the system. This is because this is the only portion that differs from earlier RO designs. Pertinent design considerations include conversion rate optimization, pump selection, and operating pressures. Some important operating procedures and characteristics are start up, high pressure regulation, conversion rate optimization, flow balancing, and shutdown. Although application of the pressure exchanger is simple in both theory and practice it is vastly different from typical SWRO design and operation. These differences affect the design and operation of SWRO systems in surprising ways that can be used to improve other aspects of system performance beyond the scope of energy consumption alone.

2.0 PRINCIPLE OF OPERATION

The PX unit utilizes the principle of positive displacement to transfer the energy in the reject stream directly to the feed stream. It is interesting to note that the reject stream is continuously and directly connected to the feed stream. This direct connection allows a real net transfer efficiency of energy from the reject stream to the feed stream of over 95%. The PX device uses a cylindrical rotor with longitudinal ducts parallel to its rotational axis to transfer the pressure energy from the concentrate/reject stream to the feed stream.
The rotor spins inside a sleeve between two end covers with port openings for low and high pressure. The low-pressure side of the rotor fills with seawater while the high-pressure side discharges seawater. The rotation simply facilitates the valving mechanism, which is to transport the ducts from one side to the other.
By rotation the ducts are exposed to the low pressure feed water, which fills the duct and displaces the reject water. The rotor continues to rotate and is exposed to the high-pressure concentrate, which fills the duct from the opposite direction, and displaces the feed water at high pressure. This rotational action is similar to a Gatling machine gun firing high-pressure bullets and being refilled with new seawater cartridges from the muzzle. A liquid piston moves back and forth inside each duct creating a barrier that inhibits mixing between the concentrated reject and new seawater streams. At 1500 rpm one revolution is completed every 1/25 second. Due to this short cycle time, membrane feed water concentrations typically increase only 1%-2%. See Figure 4-1 below.

Applying PX pressure exchanger technology to SWRO is different from conventional energy recovery device system design, but in practice is quite simple. The reject brine from the SWRO membranes is passed into the PX unit, where its pressure energy is transferred directly to a portion of the incoming raw seawater at up to 97% efficiency. This seawater stream, nearly equal in volume and pressure to the reject stream, then passes through a high-pressure booster pump, not the main high-pressure pump. This booster pump is making up the pressure losses across the RO membrane (approx. 2 bar), PX unit(s) (approx. 1 bar) and piping losses (approx. 0.5 bar). The total head provided by the boost pump is typically around 3.5 bar. See figure 4-2 and table 4-1 below.

It is important to notice that the PX and associated boost pump are handling nearly 100% of the reject flow. The size of the main high-pressure pump has been reduced to a make up pump for the permeate flow that is exiting the RO system. Product water flow and reject flow are being provided by two independent pumping systems and therefore are independent of one another.
Since the PX unit is providing nearly 100% of the reject flow at over 95% efficiency there is very little energy penalty associated with increasing this flow and thereby lower the conversion rate of the RO system. At lower conversion rate the pressure required to produce the same amount of product water is lower. Since the main high-pressure pump flow equals the product water flow an energy savings is actually achieved at lower conversion rates.

3.0 CONVERSION OPTIMIZATION

There are many factors that effect RO conversion optimization but none has been more influential than energy consumption. This is because energy costs can be as much as 75% of the entire operating cost of an SWRO plant. In the past the sewater to fresh water conversion rate has had a major and direct impact on the energy consumption of an RO plant. This is because of the inherent shortcomings of the energy recovery and pumping devices that have been used such as the Pelton wheels, turbines, and pumps. These technologies have real/overall net transfer efficiencies of 40-70 percent and are designed to pump the entire feed flow of an RO plant. Therefore at lower conversion rates these inefficient devices are pumping more water. The only way to make these devices pump less water and thereby consume less energy is to increase the conversion rate of the RO system. This is all very logical, and with rising energy costs it is natural that SWRO systems are now being designed at the membrane challenging conversion rates of 50-60%.

System designs with the PX device are different. This is because the PX, a 95% efficient device, is pumping the reject water independently of the product water being produced. The overall energy consumption of an SWRO plant using the PX device has a low point at conversion rates typically between 30-40%. Outside these conversion points the plant will start to consume slightly higher amounts of power. See figure 3 below.
It is important to remember that with the PX device the main high pressure pump flow approximately equals the product water flow. At lower conversion rates it requires lower pressure to produce the same amount of product water. Therefore, the main high-pressure pump will consume less power pumping against less pressure at the lower conversion rates. This phenomenon yields the net energy decrease shown in Figure 3.
Another important point to consider is water quality. In the past, system design had to balance high conversion rate with good water quality. In high salinity applications this has been a difficult challenge. Figure 4 below shows how a lower conversion rate yields better water quality.

Logically combining the kWh/m3 vs Conversion Rate curve of Figure 3 with the diminishing water quality curve as the conversion rate increases in figure 4 shows us that there are good reasons now to consider SWRO designs with lower conversion rates. There are also additional benefits associated with lower conversion rate designs such as ease of operation, fewer cleaning cycles, longer membrane life and a better balance of flux (GFD) from the lead element to the end element in an RO pressure vessel. Figure 5 below shows how GFD is balanced as the system conversion rate lowers(5).

Of course decreasing the system conversion rate does have its disadvantages mainly in increasing the size of the pretreatment system. This effect is less significant in smaller systems under 1000 m3/day because of the less expensive piping materials, pressure media filtration systems and other components typically employed in these systems. However on larger plants using open seawater intakes with large-scale gravity feed media filtration systems, and when the chemical additions associated with coagulation are significant operating costs, conversion rates between 45-50% may be more practical.

Potable Water from Sea and Wind

Western Australia's Water Corporation is on track to produce drinking water form a 45GL/a desalination plant located in Kwinana, 25km south of Perth. The plant is being built by proAlliance - a 50/50 joint venture between West Australian construction company Multiplex and French water treatment company Degremont. Degremont will operate the 140,000m3/d plant for 25 years under a public-private partnership with the West Australian government-owned Water Corporation. The construction cost is $387 million.


To reduce the environmental impact of the project electricity for the desalination plant will be produced from a wind farm located 30km east of Cervantes in WA's midwest. The 80MW wind farm has been engineered by the Queensland government-owned power generation company Stanwell Corporation and WA private company Griffin Energy. The wind farm will be operated by the WA government-owned power utility Western Power.

When complete Perth's desalination plant will ease pressure on WA's Integrated Water Supply Scheme. 45GL represents the single biggest water source feeding into the IWSS. To maintain water supplies for Perth's growing population the Water Corporation is pursuing a strategy of "security through diversity" and so is progressing engineering on a further desalination plant as well as developing the underground Yarragadee Aquifer to the south of Perth.

The Corporation has had to accelerate installation of water desalination due to reduced rainfall in Perth's catchment areas.

The technology to be used for the desalination plant is reverse osmosis. Osmosis is a natural phenomenon that occurs when water diffuses through a semipermeable membrane to equalise the concentration of salt in a solution. The transfer of water is from the dilute to the concentrated solution. By applying energy in the form of water pressure water can be made to move in reverse from a concentrate solution to dilute solution - hence the term reverse osmosis.

A semipermeable membrane acts like a molecular sieve allowing water particles to pass through while stopping dissolved salts, viruses and bacteria. To reduce the area required to house the membrane, the membrane is wound onto a spiral. Water is pumped under pressure down the spiral and migrates to the centre.
In recent years improvements in membrane manufacture and energy recovery devices have reduced the capital and operating costs. The Perth plant will produce drinking water at less than $0.95/kl at the fence. Electrical power consumption is expected to be less than 4.5Wh/kl.

An important part of reducing power consumption is the energy recovery system which uses a ceramic pressure recovery device. A device called the Pressure Exchanger (PX), a trademark of US firm Energy Recovery, uses a cylindrical rotor with longitudinal ducts parallel to its rotational axis. The rotor spins inside the sleeve between two end covers with port openings for both streams. Pressure energy is transferred directly from the high-pressure concentrate/reject stream to the low-pressure feed/seawater stream. A liquid piston moves back and forth inside each duct creating a barrier that inhibits mixing between the streams. The low-pressure side of the rotor fills with seawater while the high-pressure side discharges seawater. This rotational action is similar to that of an old-fashioned machine gun firing high-pressure bullets that is refilled with new seawater cartridges while spinning around a central axis.

When complete the plant will employ 16 people and provide valuable technical expertise in operating a large-scale reverse osmosis plant. A comprehensive environmental monitoring program is an operating license condition to ensure that the marine environment, near the seawater inlet and brine outlet, will not be harmed.

Seven Seas Water received a production Pressure Exchanger for evaluation in conjunction with the ADA workshop held in St. Croix, USVI in October of 1998.

A paper dealing with the performance of the device was delivered by Mr. Leif J. Hauge, President of Energy Recovery Inc. at the workshop. Tours were conducted at the test facility where the Pressure Exchanger was in operation.

TESTING PARAMETERS

It was decide, in discussions with Mr. Hauge, to deviate from the standard system design and determine if the Pressure Exchanger could be used to increase the capacity of an existing plant by utilizing the available waste energy. The pressure boost pump would also be eliminated to further simplify installation and evaluation. The Exchanger would act as a stand-alone pump using only waste energy to operate a separate bank of membranes. The Exchanger would be supplied with a separate source of filtered seawater.

INSTALLATION

The first impression of the Pressure Exchanger is the compact size and the simplicity of external design. The simplest way of mounting the system was to fabricate a mounting system that would allow a horizontal, wall mount of the device. This was completed and piping fabricated to meet installation requirements. Instrumentation was added to allow evaluation of the performance.

START-UP OF THE SYSTEM

The pre-existing membrane system was being operated at 940 PSI with a feed flow of 39 GPM. Recovery rate was at 39%. Pre-treated seawater feed pressure was 25-32 PSI depending upon state of filters.

Without displaying the math, we had available 23.8 gallons per minute at 930 PSI (10 PSI differential) to operate a bank of three, eight-inch membranes, a very marginal feed supply. Also the Exchanger was designed for an optimum flow rate of 40 GPM. Since the Pressure Exchanger is primarily centrifugal in design, it was expected that some portion of the feed water pressure would translate to the discharge of the pump.

In starting the system, it took the Pressure Exchanger several minutes to ‘wind up’ as it does any turbine device. Within 15 minutes, the entire system had stabilized. Because the Exchanger had taken place of our concentrate control valve (and was oversized for the application) the feed pressure to the primary bank of membranes was only 855 PSI. Using the installed valve on the Exchanger we only increased the back-pressure to allow the primary bank to operate at 940 feed inlet.

The secondary set of membranes, powered only by the Exchanger, was then adjusted by slowing closing the concentrate control valve.

David Laker, also with Seven Seas Water, and well-known as a pioneering reverse osmosis engineer with over 30 years of experience in the field, described the results as being as close as he had ever seen to "a perpetual motion machine."

Within the limitations of the instrumentation we were now making 8,900 gallons per day of "free" water. The secondary set of membranes was operating at a calculated 23 GPM at 935-940 PSI and producing 6.2 GPM at 400 TDS. It was later determined that cross leakage within the Exchanger was less than 2% and the actual overall efficiency of the Exchanger was 96% allowing for feed water pressure.

PROBLEMS IN PARADISE

After a short time running, it was noted that the seawater break tank was going down. The seawater feed pump was not large enough to continually feed the plant with the additional feed requirement.

A large pump was purchased and installed, but the feed flow did not increase sufficiently to allow the plant to run without interruption. It became clear that marine growth in the intake pipe was the root problem. The plant continued to operate in a "batch" mode for a short period of time. The plant was subjected to repeated starts and stops, without incident. All starts and stops were automatic and very smooth in nature.

Within a few days, the product water storage tank was at capacity and the plant shut down. Due to the difficulty and expense of installing in a new seawater intake system, it was concluded that long term testing of the Pressure Exchanger was not practical at this location.

During the week of running, the Exchanger membrane system produced 62,000 gallons of water. Overall recovery was 20%, including multiple shutdowns. The only kilowatts consumed were associated with the seawater feed pump and increased pumping requirement of the post-treatment of the permeate.


SUMMARY

The testing carried out indicates that utilizing the Pressure Exchanger for plant expansion is not only feasible, but is extremely practical.

A 40,000 GPD plant without energy recovery would produce sufficient waste energy to allow easy expansion to 60,000 GPD using the Pressure Exchanger. If boosting the membrane feed pressure became a necessity, utilizing a small energy recovery turbine and the waste energy of the secondary membrane system is certainly possible, and should be explored. Seven Seas Water currently has such a system designed and installed, waiting for the client to order start-up.

This seems to be truly amazing device that allows several potential applications in our industry. We have no doubts of the viability of the Pressure Exchanger in the seawater reverse osmosis industry. We only have one question:

How fast can an eight-inch model of the Pressure Exchanger be available for use on very large-scale plants?

Continued from Desalination Part 3: Getting Better All the Time.........

A bigger problem may be the leftover brine, which typically contains twice as much salt as seawater and is discharged back into the ocean. So far little scientific information exists about its long-term effects. In the past, most big seawater-desalination plants were built in places that did not conduct adequate environmental assessments, says Peter Gleick, president of the Pacific Institute, a think-tank based in California that published a report on desalination in 2006. But as plants are built in areas with tighter environmental restrictions, more information is becoming available.

Some recent measurements from Perth are encouraging. Initially scientists from the Centre for Water Research feared that the brine discharge from the plant would increase the saltiness of the coastal environment. But a monitoring study found that salinity returns to normal levels within about 500 metres of the plants’ discharge units. “The brine discharge is a problem that can be overcome with good design,” says Dr Antenucci.

A separate problem may be that some metals or chemicals leach into the brine. Thermal-desalination plants are prone to corrosion, and may shed traces of heavy metals, such as copper, into the waste stream. Reverse-osmosis plants, for their part, use chemicals during the pre-treatment and cleaning of the membranes, some of which may end up in the brine. Modern plants, however, remove most of the chemicals from the water before it is discharged. And new approaches to pre-treatment may reduce or eliminate the need for some chemicals.

Based on the limited evidence available to date, it appears that desalination may actually be less environmentally harmful than some other water-supply options, such as diverting large amounts of fresh water from rivers, for example, which can lead to severe reductions in local fish populations. But uncertainties over the environmental impacts of desalination make it hard to draw definite conclusions, the National Research Council concluded. Its report suggested that further research on the environmental impacts of desalination, and how to mitigate them, should be a high priority.

The reverse-osmosis process is increasingly being used not just for desalination, but to recycle wastewater, too. In Orange County, California, reclaimed water is being used to replenish groundwater, and in Singapore, it is pumped into local reservoirs, which are used as a source for drinking water. In both cases, the treated water is also available for tasting at local water-recycling facilities. This “toilet-to-tap” approach may leave some people feeling queasy, but wastewater is a valuable resource, says Sabine Lattemann, a researcher at the University of Oldenburg, Germany, who studies the environmental impacts of desalination. “Energy demand is lower compared to desalination,” she explains, “and you can produce high-quality drinking water.”

As water becomes more scarce, people will want to find several ways to secure their supplies. Many parts of the world also have enormous scope to use water more efficiently, argues Dr Gleick—and that would be cheaper than desalination. But sometimes, making desalination part of the approach to water management may be the only way to ensure a steady supply of drinking water.

In drought-ridden Western Australia, which ordered conservation years ago, the Water Corporation has adopted what it calls “security through diversity”, otherwise known in the industry as the “portfolio” approach. At the moment, Perth’s residents receive about 17% of their drinking water from seawater desalination. Desalination makes sense as one of several water sources along with conservation, agrees Dr Antenucci. But, he adds, “to say it is the silver bullet is wrong.”

Continued from Desalination Part 2: No Salt, Please..........

In the late 1970s John Cadotte of America’s Midwest Research Institute and the FilmTec Corporation created a much-improved membrane by using a special cross-linking reaction between two chemicals atop a porous backing material. His composite membrane consisted of a very thin layer of polyamide, to perform the separation, and a sturdy support beneath it. Thanks to the membrane’s improved water flux, and its ability to tolerate pH and temperature variations, it went on to dominate the industry. At around the same time, the first reverse-osmosis plants for seawater began to appear. These early plants needed a lot of energy. The first big municipal seawater plant, which began operating in Jeddah, Saudi Arabia, in 1980, required more than 8 kilowatt hours (kWh) to produce one cubic metre of drinking water.
The energy consumption of such plants has since fallen dramatically, thanks in large part to energy-recovery devices. High-pressure pumps force seawater against a membrane, which is typically arranged in a spiral inside a tube, to increase the surface area exposed to the incoming water and optimise the flux through the membrane. About half of the water emerges as freshwater on the other side. The remaining liquid, which contains the leftover salts, shoots out of the system at high pressure. If that high-pressure waste stream is run through a turbine or rotor, energy can be recovered and used to pressurise the incoming seawater.

The energy-recovery devices in the 1980s were only about 75% efficient, but newer ones can recover about 96% of the energy from the waste stream. As a result, the energy use for reverse-osmosis seawater desalination has fallen. The Perth plant, which uses technology from Energy Recovery, a firm based in California, consumes only 3.7kWh to produce one cubic metre of drinking water, according to Gary Crisp, who helped to oversee the plant’s design for the Water Corporation, a local utility. Thermal plants suck up nearly as much electricity, but also need large amounts of steam. “A thermal plant only is practical if you can build it in such a way that it can take advantage of very low-cost or waste heat,” says Tom Pankratz, a water consultant based in Texas, who is also a board member of the International Desalination Association.

Economies of scale, better membranes and improved energy-recovery have helped to bring down the cost of reverse-osmosis seawater-desalination. Although the cost of desalination plants and their water depends on where they are, as well as the local costs of capital and operations, prices decreased from roughly $1.50 a cubic metre in the early 1990s to around 50 cents in 2003, says Mr Pankratz. As a result, reverse osmosis is preferred for most modern seawater-desalination (though rising energy and commodity prices mean the cost per cubic metre has now risen to around 75 cents). Experts reckon that further gains in energy efficiency, and hence cost reductions, will be increasingly difficult, however. According to a recent report on desalination from America’s National Research Council, energy use is unlikely to be reduced by much more than 15% below today’s levels—though that would still be worthwhile, it concludes.

Sometimes, using desalination within water management may be the only way to ensure supply.

To achieve these reductions, researchers want to find better membranes that allow water to pass through more easily and are less likely to get clogged up. Eric Hoek and his colleagues from UCLA, for example, have developed a membrane embedded with tiny particles containing narrow flow channels, producing a significant increase in water flux. The membrane’s smooth surface is also expected to make it harder for bacteria to latch onto. Depending on a plant’s design, the new membranes could reduce total energy consumption by as much as 20%, reckons Dr Hoek. The technology is being commercialised by NanoH2O, a company on UCLA’s campus.

Meanwhile, the possibility of making membranes out of carbon nanotubes, which consist of sheets of carbon atoms rolled up into tubes, has also garnered attention. A study published in the journal Science in 2006 demonstrated unexpectedly high water-flow rates. But insiders think it will be a decade before the idea is ready for commercialisation.

As desalination becomes more widespread, its environmental impacts, including the design of intake and discharge structures, are coming under increased scrutiny. Some of the damage can be mitigated fairly easily. Reducing the intake velocity enables most fish species and other mobile marine life to swim away from the intake system, though small animals, such as plankton or fish larvae, may still get caught in the intake screens or sucked into the plant.

Continued from Desalination Part 1: Tapping the Ocean

This reduced the energy consumption of sugar refining by up to 80%, says James Birkett of West Neck Strategies, a desalination consultancy based in Nobleboro, Maine. But it took about 50 years for the idea to make its way from one industry to another. Only in the late 19th century did multi-effect evaporators for desalination begin to appear on steamships and in arid countries such as Yemen and Sudan.

A few multi-effect distillation plants were built in the first half of the 20th century, but a flaw in the system hampered its widespread adoption. Mineral deposits tended to build up on heat-exchange surfaces, and this inhibited the transfer of energy. In the 1950s a new type of thermal-desalination process, called multi-stage flash, reduced this problem. In this, seawater is heated under high pressure and then passed through a series of chambers, each at a lower pressure than the one before, causing some of the water to evaporate or “flash” at each step. Concentrated seawater is left at the bottom of the chambers, and freshwater vapour condenses above. Because evaporation does not happen on the heat-exchange surfaces, fewer minerals are deposited.

Countries in the Middle East with a lot of oil and a little water soon adopted multi-stage flash. Because it needs hot steam, many desalination facilities were put next to power stations, which generate excess heat. For a time, the cogeneration of electricity and water dominated the desalination industry.

Research into new ways to remove salt from water picked up in the 1950s. The American government set up the Office of Saline Water to support the search for desalination technology. And scientists at the University of Florida and the University of California, Los Angeles (UCLA) began to investigate membranes that are permeable to water, but restrict the passage of dissolved salts.

Such membranes are common in nature. When there is a salty solution on one side of a semi-permeable membrane (such as a cell wall), and a less salty solution on the other, water diffuses through the membrane from the less concentrated side to the more concentrated side. This process, which tends to equalise the saltiness of the two solutions, is called osmosis. Researchers wondered whether osmosis could be reversed by applying pressure to the more concentrated solution, causing water molecules to diffuse through the membrane and leave behind even more highly concentrated brine.

Initial efforts showed only limited success, producing tiny amounts of fresh water. That changed in 1960, when Sidney Loeb and Srinivasa Sourirajan of UCLA hand-cast their own membranes from cellulose acetate, a polymer used in photographic film. Their new membranes boasted a dramatically improved flux (the rate at which water molecules diffuse through a membrane of a given size) leading, in 1965, to a small “reverse osmosis” plant for desalting brackish water in Coalinga, California.
The energy requirements for thermal desalination do not much depend on the saltiness of the source water, but the energy needed for reverse osmosis is directly related to the concentration of dissolved salts. The saltier the water, the higher the pressure it takes (and hence the more energy you need) to push water through a membrane in order to leave behind the salt. Seawater generally contains 33-37 grams of dissolved solids per litre. To turn it into drinking water, nearly 99% of these salts must be removed. Because brackish water contains less salt than seawater, it is less energy-intensive, and thus less expensive, to process. As a result, reverse osmosis first became established as a way to treat brackish water.

Another important distinction is that reverse osmosis, unlike thermal desalination, calls for extensive pre-treatment of the feed water. Reverse-osmosis plants use filters and chemicals to remove particles that could clog up the membranes, and the membranes must also be washed periodically to reduce scaling and fouling.