Researchers use trees to reclaim waste water from landfill
More and more landfills could soon look more like forests if some researchers get their way.
Willow trees have been planted on a nine hectare section of the a 200 hectare waste dump in Ste. Sophie north of Montreal. Waste Management, the company that runs the site, has partnered with researchers from three other companies and institutions, to use rainwater that seeps through the contaminated soil before it is treated and sent into the environment. That water is called leachate.
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“We take leachate from the site and irrigate it on a plantation of willows,” explained Yves Comeau professor of environmental engineering at Polytechnique Montreal, one of the partners in the project. “The plantation will not do all the treatment but will reduce in a significant way the cost of operation of the plant,” he said.
Leachate is usually collected and most of the contaminants removed before being discharged it into streams or lakes. For this project, a portion of that water will be used for the willows. Before the water can be used on the trees, though, some pollutants still have to be removed.
“And then the rest which contain many nutrients in the water can be sent to the plantation to favour the growth of willows,” Comeau said.
The benefit, says the team, is more than just lower cost for treating the water. It’s good for the environment.
“First of all this land was doing almost nothing for 30 years,” said Françis Allard. He’s the co-founder of Ramea Phytotechnologies, also involved in the project. “Now we can grow trees on it,” he added, “and trees consume carbon from the atmosphere.”
He said it also means less contaminated water gets discharged into the environment, and that the trees, which grow to 6 feet, will be harvested to make things like fences and mulch for gardens.
“So there’s many many benefits,” he smiled.
The pilot project ends in about two years. After that, Comeau believes that there’s a good chance that the procedure will be applied in other places in the province.