EDMONTON — After flourishing on waste water from the town’s sewage treatment plant for more than two years, Whitecourt’s biomass crop of willows and poplars was ripe for harvest.
And last week, researchers brought in three different machines to cut, chip or bundle the various varieties of the fast-growing wood.
While trees aren’t usually on the list when farmers decide what crops they will plant, these species are being tested as both fuel and a way to naturally dispose of treated waste water and sludge.
Whitecourt offered the seven-hectare site beside its treatment plant to researchers in 2006, along with an electricity hookup and an unlimited supply of waste water to irrigate the young trees with underground pipes.
“The cut last week was our second on that site. The irrigated trees were 30-per-cent larger than the ones that weren’t irrigated, and we think they will be a good fuel source for our wood-burning power plant,” says Peter Yackulik, the town’s project manager.
“The question to be answered is what will it take to commercialize this operation in the future.”
The project is part of a federally led research program, with Alberta leading the way.
Whitecourt was the first test site in Canada, and there are now five locations in the province, says Richard Krygier, a researcher with Natural Resources Canada’s Canadian Wood Fibre Centre.
Saskatchewan is also interested, and Krygier hopes what has started here will eventually be copied across the country.
The other municipalities taking part with Whitecourt — Edmonton, Camrose County, Grande Prairie and Beaverlodge — met recently with government and industry supporters to form the Alberta Rural Organic Waste to Energy Network (AROWEN) to exchange ideas and encourage others to consider their approach.
“There are now 24 municipalities, companies or government departments working on this project,” says Krygier, listing an irrigation firm, a nursery company and a laboratory.
The research may provide an alternative way to treat waste water. Most areas with fewer than 5,000 residents still use lagoons and primary treatment systems, which eventually discharge into streams and rivers.
Larger centres with state-of-the-art sewage systems, such as Whitecourt and Edmonton, still have to dispose of the leftover sludge.
Researchers are studying the effects of applying this material to fields of willow trees, where it breaks down and acts as a natural fertilizer.
Edmonton’s project involves using sludge with trees on a test plot near the new remand centre being built on the city’s northern outskirts.
These trees produce biomass that can be burned for heating or to generate electricity, or in the future could be used in bio-products such as chemicals and drugs.
At the Whitecourt site, Krygier says five varieties of willow and two types of poplar were planted on irrigated and non-irrigated land.
The waste water is the same highly treated effluent discharged into the river, so it really can’t be considered sewage.
“This was our first project and we weren’t prepared to work with something that was a little ‘fresher’,” Krygier said, referring to sewage treated only to the primary level.
Using soil moisture sensors, irrigation occurred when the young trees were so dry they needed extra water.
Irrigation only works during the growing season, so a town relying on willow fields would need a winter waste water storage site, such as an engineered wetland, Krygier says.
Harvesting was done with a Claas unit, which did a good job quickly chipping the stalks, a baling machine and a cane cutter pulled behind a tractor.
It’s a new application for equipment many Alberta farmers are already accustomed to using. Farmers also have plenty of experience handling chipped material (silage for dairy cows) and round bales of hay and straw.
“But you are talking $35,000 for the cutter, $140,000 for the round bailer and $160,000 for the Claas head unit, so we were demonstrating different equipment scales of harvesting.”
The willow and poplar chips are being dried in the yard of Edmonton’s Northern Forestry Centre, testing a new technique adopted from Ireland — pumping air through slotted pipes under the pile — that has been modified by a local grain-drying firm.
“In Ireland they could dry wood chips with 45 to 50 per cent moisture content, which is what they are right now in winter, down to 18 to 20 per cent in four months,” Krygier says.
The chips will be studied and graded at a national forestry research lab to determine their quality.
Other countries, such as Sweden, have plantations of fast-growing trees harvested every few years just like crops. If it makes economic sense, large areas of brush land, marginal farmland and even the land under power lines could support willow crops in Alberta.
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Using wastewater to irrigate short rotation crops delivers dual dividend (Logging and Sawmill Journal, Nov 2011)
For more information about this method, contact Martin Blank at (780) 435-7309 or Martin.Blank@nrcan.gc.ca, Richard Krygier at (780) 435-7286 or firstname.lastname@example.org, or Derek Sidders at (780) 435-7355 or email@example.com