Farmers in Alberta successfully using sludge from Alberta Newsprint, Millar Western and Slave Lake Pulp mills for fertilizer, saving mills expense of burning, landfilling
November 14, 2011
(The Edmonton Journal)
– When folks at the Alberta Newsprint Company first noticed tomatoes growing in their pulp effluent sludge, they had a chuckle.
"We figured since there was a small amount of sanitary waste treated on our landfill site, and since tomato seeds pass through the human digestive system, that a tomato-eating staff member was the source," joked Dan Moore, environmental co-ordinator for the Whitecourt papermaking plant.
"But the bigger question was, 'Why was the pulp sludge so plant-friendly?' " So they called in researchers. And what followed was a decade-long project that has changed the way three
Alberta pulp mills are allowed to handle their sludge.
The results of the work led to the end of expensive burning and landfilling of the sludge, and provided local farmers with an excellent fertilizer. In the future, it may offer oil and gas companies a better way to reclaim former well sites.
"This project begun in 1992 by Terry Macyk (of the former Alberta Research Council) really put the province at the forefront on this issue. The three pulp companies came together and helped fund the research. They didn't have to do this and no one forced them to do it," said Bonnie Drozdowski, reclamation team leader at Alberta Innovates Technology Futures.
The sludge is composed of residue from the mechanical pulping process used at three mills (the rest use a kraft process which requires more chemicals) and contains carbon matter and nutrients. Alberta Newsprint, for example, produces 800 tonnes a day of newsprint sold to newspapers all over North America - including to The Edmonton Journal - and 30 tonnes of sludge.
The two other mills - Millar Western in Whitecourt and Slave Lake Pulp - produce more sludge to make the larger quantities of pulp they sell to secondary manufacturers of products ranging from fine paper to baby diapers to cardboard.
The goal of the research was to ensure that the nutrient-rich sludge could be safely applied to agricultural land to improve the soil. The project started with laboratory work and quickly moved to field trials. The yield results were stunning for grasses, crops and trees.
Trees on the test plots grew about 20 per cent faster, and are projected to reach a harvestable size in 60 years versus the normal 70 to 80 years.
Trials in areas such as former oil and gas well sites are still underway. It is hoped the sludge will help detoxify land as well provide a base for better reclamation and regeneration on marginal lands. Early results are promising.
There is also the potential of selling sludge as compost to garden centres.
But today, the sole use is by agriculture and there is a long list of farmers who want the sludge.
"When we started this, I would drive around and try and convince people to use the stuff. Now I get all the phone calls and repeat customers," said Moore.
Jeff Shipton, environmental coordinator for the Millar Western mill, says farmers actually stop his trucks to get information.
"We have a dedicated trucking company to haul this product, with boxes that don't leak because the sludge resembles porridge," he said.
(It is 80-per-cent water.) Under Alberta Environment rules, which were developed because of the research project, farmers are allowed to apply up to 80 tonnes of sludge per hectare, although the average is about 50 tonnes.
Shipton's firm pays to have the material incorporated into the top 15 centimetres of soil, while the sludge from Moore's operation is a different consistency and farmers are able to spread it
"We spread mostly in the Green Court and Mayerthorpe areas (south of Whitecourt)," said Shipton.
The firms usually don't truck the sludge more than 45 kilometres from their mills.
The farmers get a "lovely slowrelease fertilizer that enhances the soil properties and alters the physical structure of the soil, increasing its water holding capacity, porosity and aeration," said Drozdowski.
Once applied, it provides a benefit for at least five years which means farmers are freed from applying expensive fertilizers.
The mills would love to charge for the material, but they won't.
"It is hard to convince a farmer to pay for it in this part of the country, but it might be different if we were located near areaswith big cash crops like wheat, where the savings in (commercial)fertilizer use would be significant," said Moore.
But the mills aren't complaining.
"If we had kept doing things the same way, by landfilling, wewould have had to build two more landfill sites by now at a verylarge cost.
We produce enough sludge to fill up Rexall Place every few years,"Moore added.
The other two mills in the program were burning their sludge, an expensive process that meant it had to be dried and mixed with woody material, like sawdust.
"Our beehive burner is 20 kilometres out of town, so no longer dealing with all those costs has been a saving. But the sludge-spreading program is still relatively expensive for us,"
In a world that is trying to reduce carbon dioxide emissions, Drozdowski said the sludge project proved to be a winner by bothreducing CO 2 from combustion and sequestering carbon in the soil.Her team even wrote up a protocol for carbon credits, the sam eway farmers who practise zero tilling earn credits that have cashvalue - firms that emit large amounts of CO 2 have to purchasecredits or pay into a research fund under Alberta's carbonregulations.
"Under the protocol we were technically approved. But because westarted doing this before 2001, the project is ineligible. Wekinda got punished for being an early actor," she said.
So after years of early research and then more years ofmonitoring, the pulp mill sludge project has entered a new stage.
"We now are getting the message out across Canada, because many mechanical pulp mills are still landfilling or burning their sludge," said Drozdowski.
B.C.'s two mechanical mills are looking at what Alberta has done, as are mills in Ontario.
And the project has just launched a website which details the research.
"We want everyone to be aware of this project, that Alberta is an environmental leader with almost 20 years experience studying this sludge," she said.
The team has taken the sludge project from the very beginning, from an observation about tomatoes, to an idea that might be worth
examining, through the research stages to having enough science to establish provincial regulations, and now seeing farmers l ining up to use it.
"At the end of the day we have a nice green product that people see has value," said Drozdowski.
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