Case Study Detail

PX® Technolgy Reducing Energy and Overall Costs

The Industry Standard Solution
The efficiency and lifecycle costs of a plant’s energy recovery technology is critical to both winning SWRO projects and achieving maximum plant profitably through the lowest operating costs. Leading international OEM’s such as Acciona Agua, Aqua Engineering, Befesa, CH2MHill, Cobra Tedagua, Doosan Hydro Technology, Fisia Italimpianti, GE Water Process and Technologies, GEIDA, IASUR, INIMA, Metito, Siemens and Suez Degrémont have selected the ERI PX modular technology for their recent 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.

Maspalomas I Project Facts

• CAPACITY: 3,000 m3/day [.8 MGD]
• 2 trains - 1,5000 m3/day [.4 MGD]
• 2 PX-180 PRESSURE EXCHANGERS PER SWRO TRAIN
• 95% EFFICIENCY GUARANTY
• PLANT STARTUP – JANUARY 2007
• ENERGY CONSUMPTION – 2.05 kWh/m3

“Our relationship with ERI personnel has been excellent; from pre to post-sales as well as technical advising during commissioning and follow-up visits.“

  ELMASA

The Situation
The Canary Islands consists of seven dormant volcanic islands. They are located off the west coast of Morocco and are an autonomous community of Spain. Public services for San Bartolome de Tirajana, a municipality on Gran Canaria, are managed by Eléctrica Maspalomas S.A. (ELMASA). Water supply, sanitation and sewage treatment are provided by works located at San Bartolome de Tirajana Municipality.

As tourism is the island’s primary economic resource, ELMASA plays a vital role providing much needed water for the typically dry region. In 1986, an electrodialysis reversal desalination (EDR) plant was built to treat the area’s brackish water. Since 2006, ELMASA has retrofitted the EDR plant with PX Pressure Exchanger™ (PX™) technology to provide a seawater reverse osmosis solution that has significantly reduced energy consumption and CO2 production by the plant.

The Challenge
The original 20,000 m3/day EDR plant was implemented to treat brackish water. As time passed, the salinity in the brackish water coming from the wells increased dramatically. As a result, electrical consumption increased while permeate production decreased. In 2006, plant productivity had dropped to only 12,000 m3/day. While EDR works well in certain applications, in this case it became impractical. The process eventually consumed approximately 3.1 kWh/m3 for EDR alone and additional power was required for pumping. As such, the process became very expensive to operate. Additionally, the challenge of underground water scarcity was a real concern.

The Solution
In 2005, ELMASA decided to replace EDR with reverse osmosis (RO). Having several years of experience designing and working with ERI’s PX Technology, the company initiated a four stage plan. In each stage, ELMASA will replace 3,000 m3/day of production. The first stage was executed between June 2006 and December 2006. The following changes were implemented:

• Two RO trains, 1,500 m3/day each, were constructed, each consisting of one positive displacement pump and two ERI® PX-180 Pressure Exchanger devices
• Seawater intake wells were constructed
• Seawater conduction piping was installed. The plant is 3.5 km away from the intake
• Concentrate disposal pipe was modified ERI provided services including commissioning and initial training.

ERI will also provide equipment and services for the next three stages, helping add 9,000 m3/day of additional water production capacity.

The Result
With the new RO system which includes PX technology, the specific energy consumption of the SWRO process is 2.05 kW/m3 (without feed and product pumping) for a savings of 1.05 kW/m3 in power costs compared to the EDR process. The energy of Gran Canaria is produced by fuel oil plants, consequently, CO2 emissions have been reduced by 1 ton per year as a result of the retrofit. The final results were extremely positive: the process consumes less energy to produce the original design capacity, is contributing to a reliable water supply for the municipality, and notably is helping the environment through reduced CO2 emissions.

Energy Recovery, Inc. (ERI®) is a leading manufacturer of energy recovery devices, which help make desalination affordable. ERI’s PX Pressure Exchanger™ technology (PX™) 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.

ERI 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, Dubai, Shanghai and Florida. ERI service representatives are based in Algeria, Australia, China, India, Korea, Mexico, Taiwan and the Caribbean.