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Desalination
Salty Solution?
Five years and $40 million over budget, the largest desalination plant in North America is finally producing fresh water for the Tampa Bay Region.
The Desal State
Marco Island on the southwest Florida coast, just six miles long and four miles wide, bustles with 40,000 residents and visitors during the winter. A reverse-osmosis plant provides the island's residents with 6 million gallons a day -- the water it filters is among the highest salinity water in the United States that ends up as tap water.
Among the 250 smaller-scale desal plants that filter and purify water around the nation, Florida has more than any other state, with 120 plants along both coasts. Texas has 38, and California, 33. Both of those states have significant plans for seawater desalination but are closely watching Tampa Bay's plant, the first large-scale desal plant in North America and the first to filter seawater.
Most of the Florida plants rely on reverse-osmosis filtration through membranes to remove salts, calcium and other substances from brackish water. They don't have to pretreat the brackish water as extensively as facilities that filter seawater -- one source of technical troubles that plagued the Tampa plant.
A couple of the largest include a 20-million-gallon-a-day plant in Collier County and an 18-mgd plant in Hollywood. A 40-mgd nanofiltration plant -- similar to reverse osmosis but removing slightly fewer ions -- recently went into service in Boca Raton and is the largest of its kind in the Western Hemisphere.
In 1995, Sarasota County built a desal plant with a technology called electrodialysis reversal (EDR) that uses electricity to separate salt and other minerals. The largest EDR plant in the world, the Sarasota facility was designed to produce 20 million gallons a day.
"Perhaps you don't hear about these plants," says Steve Duranceau, an Orlando-based engineer who's helped design several of the Florida plants, "because they work so well."
Tampa "has really delayed seawater desalination projects in this country," he says, "but people have to realize that communities have been successfully desalting brackish water on the west and east coasts of Florida for 20 years."
Business: The Desalters
In 2005, South Korea engineering powerhouse Doosan built the Fujairah, one of the largest desalination plants in the world, in the United Arab Emirates. Last year, when Doosan decided to set up research and development subsidiaries on both sides of the globe to strengthen its desal capacity -- the company says it controls 40% of the worldwide market -- it chose Dubai and Tampa.
Doosan Hydro Technology is one of the first companies to make Florida a strategic base for tapping the seawater desalination market in the Sun Belt -- a market expected to boom when Tampa Bay's plant becomes fully operational. Florida, Texas and California all are considering major seawater desal efforts as an alternative source of fresh water to supply population growth.
Another company to watch is Boca Raton-based Water Standard Co., which has spent the past six years developing a Seawater Desalination Vessel and is heavily promoting its concept of ship-based mass desalination with the help of Tampa-based engineering firm PBS&J. Last fall, the Monterey Peninsula Water Management District in California voted to study the vessel as a possible source of fresh water for the region.
