Wetland for Cleaning up Polluted Water

BioHavens wetlands are made up of recycled plastic drink bottles, shredded and injected with a polymer foam to create a buoyant matrix in which native grasses and aquatic plants are planted

One day in 1999, he watched as his black dog jumped into a pond and came out streaked with rusty orange. It had encountered an algal bloom of cyanobacteria. Such blooms can be toxic. This one wasn't, so the dog, after being cleaned up, was none the worse for its experience.

But that experience eventually led to Kania's invention of a form of floating wetland for cleaning up polluted water, and to launch a company called Floating Island International.

The firm is based in Shepherd, Mont., on about 140 hectares of land along the Yellowstone River. Several ponds dot the property, a couple of which he had had dug out and filled so that they became living laboratories.

One of them, Fish Fry Lake, figures in a lot of the things he writes, usually pertaining to the idea of biomimicry, an interest that drives his research and product development.

Kania is a long-time outdoorsman, an avid fisherman who grew up fishing the waters of Northern Wisconsin. Some of the best fishing was round islands of peat floating on clean, clear water. His purpose in digging ponds on his Montana property was to see if he could re-create those floating islands.

His Fish Fry Lake is a small pond, with a surface area of just 2.5 hectares, or 6.5 acres. But after it had been filled with water, he said in a recent interview, "I ended up with 6.5 acres of solid algae."

"There were patches of cyanobacteria with orange colours, and blue colours, and stuff that made you really concerned about your dog perhaps taking a sip.

"Now I've got water clarity that can extend as far as 19 feet.

What cleaned up the water was, of course, the floating islands Kania had invented, islands similar in function to the peat he had seen years before in Wisconsin.

The islands, which he christened BioHavens, are made up of recycled plastic drink bottles, shredded and injected with a polymer foam to create a buoyant matrix in which native grasses and aquatic plants are planted. Eventually, the plant roots permeate the matrix and extend below the island, providing shelter for fish and all manner of other aquatic creatures.

As the root systems grow, they become coated with biofilm, which is simply microorganisms in which the cells stick to each other, eventually coating the roots and other surfaces, like rocks, with slime. That slime absorbs nutrients like phosphorus from the water. It also captures and holds particulate material, clarifying the water in the process.

That's precisely what the peat islands of Kania's youth do. His floating islands had duplicated Nature's process for clarifying and purifying water.

Source: DAILY COMMERCIAL NEWS 

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• Wastewater Treatment
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