Floating Islands

Question: I’ve heard that floating islands can play an important role in treating wastewater and controlling algae. How is this possible?

Answer: Floating islands, sometimes called Floating Treatment Wetlands, are a fascinating technology that are being used in a variety of applications, including nutrient and pollution removal, wildlife habitat and wetland restoration, storm water management, management of effluent ponds and wastewater treatment.

The islands begin as a matrix of buoyant recycled material (such as shredded plastic drinking bottles) that resemble a loofah. This recycled material is then covered with a geotextile layer, soil and other materials to complete the physical structure. Plants appropriate to the growing conditions are added, and the island is either set free to drift or anchored in a convenient location. Roots from the plants grow down into the water, providing shelter and food for fish and beneficial microbes, while the surface provides a habitat for birds and other wildlife. Floating islands can be any size, and can be engineered to support a significant load. Since the island floats, it is not affected by changing water levels such as flooding.

The key benefit of floating islands comes from its interaction with the water. In many ponds and lakes near farm lands, as well as in manmade ponds, algae is a big problem. Fertilizers washed off during rains flows into natural ponds, groundwater and manmade catchments such as storm water runoff ponds. Algae flourishes in water that has an excess of nutrients such as phosphorous and nitrogen, and chokes out other forms of life, leaving an ugly, smelly mess. The plants growing on floating islands, however, readily absorb excess nutrients in the water and even cleanse the water of many types of pollution, including some heavy metals. Among the submerged roots of the island, colonies of microbes form that treat the water by consuming and thriving on large quantities of otherwise harmful nutrients.

The potential uses of floating islands for wastewater treatment, wetlands restoration and algae mitigation have spurred a variety of research projects regarding the specific capabilities of different plant types to absorb and cleanse the water of harmful substances. Floating islands are cost-effective to build, easy to use and maintain and are largely made from recycled materials. The BTL Liners team is excited about the continuing development of this technology.

For more information about floating ponds, please visit www.floatingislandswest.com.

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