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‘Floating island’ tech helps in wetlands process

0 322 Technology


Science has known understood the value of wetlands for years. Getting people to take advantage of wetlands is another matter.
‘Floating island’ tech helps in wetlands process

Marshes are often viewed simply as something that has to be drained before land development can begin. They are, in the eyes of many, simply one more cost that must be met.

But because they are valuable, they are protected and enhanced in some areas. And constructed wetlands have often been built. The development of "floating island" technology has made that a much simpler process. These islands can be used to begin water treatment in stormwater management ponds. They can be used to "cap" sewage lagoons where odour has become a problem. They can be used to treat landfill leachate in areas where that occurs. They can even be used as docks in marinas, where customers are not always careful about what they dump overboard.

Floating Island International is a Montana-based research facility which devised a system of floating islands which it has called BioHavens. It has identified dozens of possible uses for the technology, sometimes with variations the company itself has devised.

Stormwater runoff can be problematic in many areas, since it can pick up oil, grease and metals from car exhausts, or nitrogen and phosphorus from fertilized grassy areas like lawns and golf courses.

At Floating Island's facility, "elevated bioswales" were devised to treat stormwater and agricultural runoff. They were tested in an irrigation ditch, where they were installed, then planted with native and domestic grasses.

The idea is that water flowing along a ditch thus also flows through the root systems, in effect beginning the treatment of the stormwater while slowing its journey to a stormwater management pond.

Many smaller communities in Canada depend on sewage lagoons to treat wastewater. It's a mature technology that is well understood. And it's much cheaper that building a conventional sewage treatment plant.

But lagoons can cause odour problems.

In New Zealand, BioHavens planted with native plants have been used to create a cap on a lagoon which was receiving municipal wastewater, landfill leachate, and waste streams from a nearby malting company.

Despite installing six aerators around the clock, the smell persisted, and the aerators needed frequent maintenance.

Waterclean Technologies, which is a licensee of Floating Island International, designed and built a BioHaven system that fit tightly over the pond.

The odour was sealed in. The pond turned into what was essentially an anaerobic digestor. And the city of Marton, N.Z., which operates the pond, has saved about $150,000 a year in energy costs for running the aerators.

Floating Island's founder, Bruce Kania, said in an interview that there are many other places and uses for floating wetlands.

"In Annapolis, Md., there's a long-term test that's still happening," he said. "And we have launched BioHavens around Baltimore, where the Susquehanna River pours into Chesapeake Bay."

As a result of the agricultural runoff the Susquehanna carries, "the western half of Chesapeake Bay is hypoxic," he said, meaning its water has extremely low levels of dissolved oxygen. So the bay, which used to produce "outrageous numbers of oysters and crabs — those life forms can't make a living on the western side."

"They die."

The company has also devised a system that aerates the water as it pushes it through a BioHaven matrix and the plant roots that extend below it.

Called Leviathan, it uses pumps, and directional diffusers to draw in and aerate large amounts of water — up to 10,000 gallons a minute.

The company sees Leviathan as a useful tool for lake restoration, and for cleaning up damage caused by oil spills and other man-made and natural disasters. It's scalable, so a small unit could be used for a small spill, larger units for larger spills.

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