Western Hemisphere’s Largest Water Desalination Plant Opens

posted: 12/15/15
by: Danny Clemens
Carlsbad Desalination Plant interior
Carlsbad Desalination Project (Handout Photo)

A massive seawater desalination plant in San Diego is now producing 50 million gallons of drinkable water per day, making it the largest such project in the Western Hemisphere.

The Claude "Bud" Lewis Carlsbad Desalination Plant, a $1 billion public-private venture between Poseidon Water and the San Diego County Water Authority, commenced operations on Monday, the culmination of nearly 20 years of planning, development and construction.

Each day, approximately 100 million gallons of water from the adjacent Agua Hedionda Lagoon enter the plant through a 72-inch seawater pipe. During the pretreatment process, the seawater cycles through a multi-layer tank that utilizes anthracite, sand and gravel to remove algae and other large impurities. A second pretreatment then removes smaller particles.

The plant relies on state-of-the-art reverse osmosis technology to remove dissolved salt from seawater; more than 2,000 pressure vessels in the facility contain semi-permeable membranes through which seawater must pass.

"These membranes act like microscopic strainers that allow only water molecules to pass through, leaving behind the salt, minerals and other impurities such as bacteria and viruses," the project's operators explain in press materials.

Carlsbad Plant interior
Carlsbad Desalination Project (Handout Photo)

After the filtration process is complete, select minerals are reintroduced to the newly potable water, which is then disinfected with chlorine. At that point, the newly potable water is pumped throughout drought-parched San Diego County. Officials estimate that the high-tech plant will satisfy 10% of the region's water needs.

Brine, the highly concentrated, salty byproduct that remains, is finally diluted with seawater and reintroduced back into the ocean.

The plant is outfitted with energy-efficient technology that is said to nearly halve energy consumption, saving 146 million kilowatt-hours of energy each year -- the equivalent of taking 9,000 cars off of the road.

Mind-blowing technology aside, the project is not without its critics. The Surfrider Foundation, a nonprofit foundation that has waged a lengthy battle against the plant, has called desalination's environmental impact into question.

"Desalination may be part of the solution eventually, but it needs to be sized and located appropriately. It should be the last tool in the tool box, not the first," the organization writes in a press statement.


About the blog:
DSCOVRD: The best of the web, covering space, technology, wildlife and more!
More on