August 24, 2007

BRENT WOOTTON

Wastewater exfiltrates through the lagoon berm into northern wetland.

Innovation

Engineered wetlands a potential solution for north wastewater

Extreme weather adds complexity to any solution

PETER KENTER

correspondent

PETERBOROUGH

Canada’s northern regions rely on diverse methods of wastewater treatment. The use of wetlands has met some success, intriguing a team of Canadian researchers who want to duplicate it by building engineered wetlands in several Nunavut communities to help determine the best way to treat wastewater in a sub-Arctic climate.

“The technology isn’t new to the north,” says Brent Wootton, senior scientist with the Centre for Alternative Wastewater Treatment at Fleming College.

"It sounds simple and elegant, but it's actually very complicated."

Brent Wootton

Centre for Alternative Wastewater Treatment

“Most of the communities have a dumping lagoon that exfiltrates through the sand and gravel of a berm down a wetland slope anywhere from a few hundred metres to several kilometres long. The wetlands are lush and green with vegetation that thrives on the wastewater while helping to treat it. What we’re finding is that in smaller communities, such as Chesterfield Inlet or Whale Cove, it works very well. The water that reaches the ocean is of very high quality.”

Nunavut’s wastewater guidelines are evolving to meet criteria set out by the Canadian Council of the Ministers of the Environment, increasing interest in why some of these systems work and others don’t.

The year spanning 2007-08 marks the International Polar Year, an event occurring every 50 years in which researchers concentrate on specific regions of the globe.

As part of the international collaboration, the federal government is funding a $700,000, four-year pilot project through Indian and Northern Affairs Canada to investigate opportunities for wetlands wastewater treatment in some of the growing communities of Nunavut.

“Very little is understood about why the successful wetlands treatment projects work so well,” says Wootton. “It’s a natural experiment that we’ve been observing without a lot of controls. What we plan to do is to characterize the processes that are occurring so we can understand what’s going on.”

Research will include laboratory experiments simulating Arctic climates and the construction of small-scale wetlands treatment systems.

“It sounds simple and elegant, but it’s actually very complicated and requires a lot of thought,” says Wootton. “One size does not fit all in the north. Part of the wetlands treatment involves the growth of certain plant species, but some of these species don’t thrive well near the ocean while others do.”

Some of the wetlands areas also provide better treatment during the summer months. “What happens in the winter when the lagoons are frozen over?” asks Wootton.

“When a community is large enough it adds warm wastewater at a rate fast enough to keep the lagoon open, but what if it freezes solid?”

Little is understood about the ability of wetlands to provide treatment during the initial period following spring thaw, when effluent may flow over frozen ground.

Another concern is the separation of industrial wastewater streams from community wastewater since, in some areas, they are combined. “Caribou, for example, will eat the wetland vegetation and people will eat the caribou,” says Wootton. “We don’t want to see heavy metals from industrial waste entering that ecosystem.”

The research will concentrate on settlements in Nunavut’s Kivalliq region so that findings will be transferable to communities sharing a similar climate along the same line of latitude.

“Using the information we collect, we hope to produce sound design guidelines around these types of systems so that consultants and construction companies can design and build engineered wetland treatment systems and enhance the existing ones.”.

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