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Saturday, March 31, 2001

Water suppliers exploring demineralization techniques

By DINAH VOYLES PULVER | News-Journal Environment Writer

DELAND — When it comes to water, Florida has access to far more of the salty variety than the fresh.

That's why utility managers from across the region gathered Friday to look at the possibilities for tapping that salty or brackish water for conversion to fresh drinking water.

The St. Johns River Water Management District conducted the workshop with a group of its consultants that's studying how to manage the mineral concentrate left over when salty or brackish water is purified.

Management of that concentrate is the tail that wags the whole dog, said consultant Robert Reiss of Reiss Environmental.

A whole spectrum of solutions was discussed Friday, from the humorous to the costly.

One consultant, Bill Conlon of PB Water, has been involved in the science for 30 years. Unless another marine-based theme park is planned, the district probably won't be able to try the best solution Conlon has seen for using the concentrate.

"We did a reverse reverse osmosis project for SeaWorld," Conlon said. "We put the concentrate in Shamu's tank and had to find a way to use the fresh water."

In Israel, where desalination is widely used, the concentrate is in big demand for cosmetics.

"We're constantly trying to think of new ways that are economical and environmentally friendly to dispose of the concentrate," Conlon said.

However, at least for the short-term, the solutions in Central Florida will be much more mundane. The options include discharging the concentrate into brackish surface waters or spraying it onto fields. One of the more controversial options is the injection of the concentrate underground. The state Legislature is taking a look at that option this session.

Although demineralization has been used for many years, the great majority of municipal facilities in the United States are less than 5 years old, said Ed Weinberg, with EW Consultants Inc.

"The long-term effects are not necessarily understood nor is there that much information," he said.

The district's consultants plan to study all the existing reverse osmosis and desalination plants in Florida and how those plants dispose of their concentrate.

The most significant final product of the study will be a complex mapping system that utilities can use to study possible locations for a plant and the potential problems within that area, Reiss said. The study also will list all the environmentally sensitive water bodies, characteristics of the Floridan aquifer system and significant wetlands.

An actual project or pilot project, Reiss said, would require further study and permitting. Those studies would have to look at the impacts on invertebrates and animals in a waterway if the concentrate is going to be discharged into a waterway. If underground injection is suggested as an option, state officials would require a study of the geophysical traits of the ground under the proposed location.

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