Water is vital on a global scale, and the lack of readily available resources is a growing issue for developed and developing nations alike. One-fifth of the world's population has no access to safe drinking water. With the advent of desalinationtechnology, fresh water as well as industrial and commercial development has been brought to areas of the world that otherwise might have remained unproductive. Not only has community development been enhanced by this technology, but the health and welfare of entire populations has also been improved by the supply of clean and fresh water.
Toas Island in Venezuela is located in the middle of Lake Maracaibo – at 13,210 km2, the largest lake in South America, and one of the oldest lakes on Earth. Sadly, for the last 60 years, all that water has been unsuitable for drinking, cooking or other everyday needs due to the lake being channelled to the sea for freight traffic in pursuit of petroleum under the lake. This means that, over time, seawater has intruded.
Deteriorating water supply
Before the desalinationsystem was installed, the residents of Toas island were dependent on a corroded water pipeline that ran from the mainland and was only available twice a week for four hours. Besides this, an old, undependable barge that make two trips a week for water. Water was therefore at a premium; according to Mainor Vega, business manager, Latin America, for ITT Water Equipment Technologies (WET): “To the people on the island, water was like gold.”
Recently, the WET division, based in Florida, USA, completed the installation of a reverse osmosis desalinization system that can provide 1.5 million litres of water to Island residents each day.
Difficult site conditions made the installation a challenge, ITT says. “[…] We knew this job demanded a system engineered for the difficult site conditions,” says Vega. “To the people on the island, water was like gold.”
One of the important design features of the desalinationsystem for Toas Island was building a system that was flexible in its operating parameters. Depending on tide swings and seasonal shifts, the salt levels in this area of Lake Maracaibo can change drastically – ranging from 8,000 ppm all the way up to sea water levels of 32,000 ppm. The higher the salinity level, the more pressure is needed to push water through the reverse osmosis membranes. WET's system was designed so that operators could take constant measurements and make the appropriate pressure adjustments. This system also had to be durable enough to handle the mud, silt and suspended particles that were being pulled in from the lake.
WET is a unit of ITT, and was founded in 1975 in order to provide water solutions for global environmental problems. WET produces a variety of high technology, membrane-based water purification systems to markets including commercial/industrial, municipal and sea water desalinationfor process, potable, high purity and wastewater applications. In water desalination,the company uses ocean engineers that are trained in water chemistry, fluid dynamics, corrosion and other sciences necessary to successfully design, build and apply proper water desalinationtechniques. ITT designs, manufactures and installs seawater and brackish water RO systems with outputs ranging from 9,000 GPD.
(34 M3/D) to several million GPD (approximately 100,000 M3/D) with modular units. These systems are specifically designed to perform in harsh and corrosive environments providing the reliability, durability, performance and low life-cycle costs needed for demanding applications.
ITT's range of offerings include systems formicrofiltration (MF), ultrafiltration (UF), nanofiltration (NF) and reverse omosis (RO) applications. ITT also manufactures a variety of media filtration systems for wastewater treatment applications and builds a complete range of desalination“watermakers” to meet the severe environmental demands of the offshore drilling and production industry.
Water for 2,500 households
ITT WET's seawater reverse osmosis systems installed in Toas Island provide a water with salinity levels under 100 ppm (WHO defines fresh water as having salinity levels of 1,000 ppm – U.S. drinking water needs to be below 500 ppm). WET's seawater reverse osmosis systems installed in Toas Island provide water with salinity levels under 100 ppm, ITT says.
After it was designed, WET's system had to be transported by boat and truck to the remote island. ITT Goulds pumps are used to transport the water from the lake to the clarification tanks, the multimedia filtration system and finally to the reverse osmosis systems. The water from the desalinationplant is sent through more than 10 km of piping to a 1.5 million litre storage tank located at the highest point of the island. Gravity does the rest, supplying fresh water to the 2,500 households on the island.
Goulds Pumps include a comprehensive line of double suction, end suction, multi-stage, non-clog and vertical turbine pumps for water supply, booster, low lift, and high lift. “This is one of the poorest sections of Venezuela, but with water, they now have hope and a future.”
Vega admits that some days were a struggle, dealing with tricky political issues and problems like a lack of dependable power sources. But he says that the desalinationsystem changed the islanders' lives dramatically. “The first day with water, children were outside my window at 2am, playing in the mud because they couldn't believe there was enough extra water to even create mud. The smiles were incredible and very real,” he says.
The water is transforming the island on a larger scale, too, ITT claims. “When we first got to the island, none of the fire hydrants operated. Now, they are thinking about putting up small hotels and trying to build tourism,” says Vega. “This is one of the poorest sections of Venezuela, but with water, they now have hope and a future.”
An RO desalinationsystem marketplace can be located anywhere there is lack of adequate fresh water supplies and a good source of available seawater or brackish water, ITT says. Anywhere there is growth and development in water shortage areas, such as in Toas Island, there is a candidate for desalinationby RO.
Historically, the world market has been in the equatorial zone, arid environments, island and coastal communities. Remote communities have led the way with this technology, but as quality water sources become more and more scarce, both industry and municipalities are recognizing the need for RO desalination.In California, Florida, the Caribbean, Central and South America, the Mediterranean, Middle East and Pacific Rim (anywhere there is an ocean and a need), RO desalinationis a viable resource for the world's fresh water production requirements.
