Montreal study reveals decentralized waste management benefits

Canadian researchers are rethinking waste management strategies by studying decentralized approaches to collecting and sorting used packaging, as municipalities seek to reduce their environmental impact through managing waste volumes.

A new study published in Recycling, an international, peer-reviewed journal, suggests that decentralized waste sorting could ease environmental and economic pressures by reducing GHG emissions and offering greater operational flexibility. 

The research stresses that centralized waste collection systems, which rely on more trucks to meet increasing demand, place additional strain on road networks and exacerbate GHG emissions. In contrast, a decentralized approach creates a network of distributed facilities.

“Montreal deploys one recyclable waste sorting facility for the city. The facility separates the recyclable waste into one of the 42 considered materials, which are regrouped into papers, plastics and fibers, and metals. PET is assumed to be 1.5% of the municipal recyclable waste generated,” the researchers explain.

“Decentralization sends recyclable waste into different facilities, which makes a network configuration of the infrastructure. This configuration allows for redundancy. This approach also changes the configuration of recyclable waste collection trips.”

Emission reduction

Data from over 22,000 roads and 1.15 kilotons of recyclable waste were analyzed across six decentralization scenarios. Researchers say that in all scenarios, costs and CO2 emissions were reduced on an operational basis.

As waste collection demands grow, Montreal’s centralized infrastructure can only keep up by sending out more trucks.Compared to the current centralized model, the most effective decentralized scenario reduced GHG emissions by 20.3% and slashed operational costs by 8.04%. On average, the distance required to collect one ton of recyclable waste dropped by 35.3%, while truckloads per trip were reduced by 12.8%.

However, the study warns that while operational expenses fall, initial investment costs can increase. In the most effective scenario, these costs accounted for 89.7% of total expenses, raising concerns about economic feasibility.

“The results conclude that a single recyclable waste sorting facility near residential buildings remains a favorable choice due to high investment costs not offset by savings in operation costs. However, certain limits could favor a decentralization approach. Investment, for instance, has a fixed duration. Once the investment is over, all scenarios would see reduced costs and CO2 emissions.”

“While results show that investment remains a barrier, infrastructure mutualization of multiple waste streams could lift this barrier. This approach reduces resource consumption and infrastructure needs and involves equipment and space sharing.”

Flexibility and resilience

According to the study, decentralization shows greater adaptability in the face of rising waste volumes. 

A distributed network of facilities could be more resilient to disruptions in recyclable waste generation, which “opens the door to different vehicle sizes for waste collection and delivery of sorted recyclable waste.”

The study emphasizes that future research should focus on integrating multiple waste streams for infrastructure mutualization. Additionally, including the modeling of the sorting facilities could enhance the accuracy of this approach.

Meanwhile, to tackle the growing problem of plastic waste, the Canadian government developed an agenda to achieve zero plastic waste by 2030. The nationwide strategy outlines how the country will mitigate the role of plastics and work to promote a circular economy.