The last time city officials contemplated the type of organic waste treatment centres that are needed on Montreal Island and the places to put them was a decade ago.
And their thought process went like this: for the sake of “geographic equity,” they said, they would build four treatment plants — one in the east, one in the west, one in the north and one in the south. A fifth facility, also to be built in the east end of Montreal, would serve as a pretreatment centre.
The city’s plan has changed little since then, apart from switching the site of the future west-end plant and moving the future north-end plant further east, even though technological advances have led to new waste treatment processes and innovative uses for the byproducts they create.
The only thing that has changed substantially in Montreal’s long-awaited project to build two composting plants, two biomethanation plants and the pretreatment centre is the price: an announced cost of $237.5 million in 2013 has risen to $589 million today.
However, Montreal’s north-south-east-west “strategy” for locating the facilities elicits chuckles now from experts on waste management. That’s because the planning process has also become more sophisticated in the decade since Montreal adopted its organic waste treatment plan.
“The collection of the waste material and the waste’s characteristics, and then the appropriate treatment, and then the disposal of your end product — it all goes hand-in-hand,” said Céline Vaneeckhaute, a professor of chemical engineering at Université Laval who specializes in resource recovery from waste, or what’s known as green process engineering.
“Everything influences the other. So you cannot see one piece separately.”
Vaneeckhaute leads a research team at the university in Quebec City that is developing a computer modelling tool to simulate and then optimize a municipality’s waste treatment chain, including the transportation of waste, to help the municipality decide what type of treatment processes to use, where to locate facilities, what nutrients to recover for re-use and to help estimate the cost.
The optimization tool, called optim-O, will even make a treatment plant itself more effective, by determining the optimal mixture of waste products, the appropriate temperature and the flow rate, she said.
The team is working with the biomethanation plant in Rivière-du-Loup to carry out its first case study with optim-O, Vaneeckhaute said.
Before joining Université Laval, Vaneeckhaute worked for Quebec City on the biomethanation plant it’s building. She’s also worked as a consultant on similar projects.
The prototype of optim-O should be more reliable in a year, she added.
However, when told of Montreal’s east-west-north-south approach that defined its organic waste treatment plant project, Vaneeckhaute said she could already offer the city help to strategize for the future of its waste treatment plants.
“I think already now with what we know, because we have a lot of data, we could give them a help to optimize their system,” she said.
As the Montreal Gazette reported this week, the city is about to award a $175-million contract for the first of its five centres, a composting facility in St-Laurent borough. The contract to Suez Canada Waste Services was approved by Mayor Valérie Plante and the executive committee on Wednesday and will go to city council and the agglomeration council for final approval next week.
However, the Plante administration says it will implement the rest of the plants incrementally with the possibility of some changes.
But what type of waste treatment to use and where to locate facilities requires a “holistic view,” Vaneeckhaute said. The choices depend on the type of waste material collected, where collection is concentrated, the distance it will travel to a plant, what resources and byproducts a municipality wants to recover and create from the treatment process and where that end product is going to end up.
That’s because any waste management plan aims to reduce greenhouse gas emissions. So it’s probably not the best choice for a municipality to target recovery of phosphorous to make bio-fertilizer, for example, if the municipality is in a phosphorous-rich region of Quebec, she said. The material will only wind up being trucked father out where agricultural fields can use it.
Even such decisions as what kind of waste to feed into a composting centre or biomethanation centre is evolving, she said.
For example, think diapers have no place in a composting bin with table scraps? New research is suggesting otherwise, she said.
It appears that diapers, which are a large volume of the waste that gets sent to landfill, could be given new value — or valorized, in green process engineering parlance — through composting or biomethanation if the plastic is removed. The rest of the diaper would absorb the problematic excess liquid found at the bottom of organic trash and needs to be dried.
Her research team, meanwhile, is looking at how to valorize coffee grounds, she said.
“I’ve been working on this kind of stuff for more than 10 years now,” Vaneeckhaute said, adding that biomethanation is well established in Europe, where she’s from.
The digestate that remains following the biomethanation process is rich in nutrients, she said.
“So you really have to look at how you treat it and how you can recover the nutrients in a concentrated way. That’s really, in my opinion, the future. It’s innovative for Canada, but it’s there and exists and it works.”