WC141 MarApr 2025 - Magazine - Page 14
TOP 50 PROJECT
River Revival
Montréal’s wastewater plant upgrades tackle
pollution in the St. Lawrence with cuttingedge ozonation and sustainable sludge
management.
BY SAUL CHERNOS
ITH ELEVATED concentrations of bacteria and other pathogens documented
in the St. Lawrence River close to Montréal’s wastewater outflows, it became
clear that the Jean-R.-Marcotte Wastewater Treatment Plant needed tender loving care.
The plant, on the eastern tip of Montréal Island in
the borough of Pointe-aux-Trembles, processes and
releases up to 2.3 million cubic metres of wastewater
daily into the St. Lawrence, and offers a peak treatment capacity of 7.8 million cubic metres.
While a much smaller plant treats sewage and
stormwater generated on Montréal’s Notre-Dame
Island, the Jean-R.-Marcotte plant receives wastewater from the rest of the city and most of its suburbs.
With enormous 43-metre-deep suction wells, a litany
of pumps, motors and generators, and more than
350 employees to keep things running smoothly,
the plant, built in 1984, ranks as one of the world’s
largest of its kind. Screens weed out large particles,
coagulants reduce phosphates and improve settling
efficiencies, decantation and removal systems handle
sludge, and four large incinerators transform nearly
700 tonnes of dry pellets into ash every day for
disposal off-site. The treated water is then directed
through a series of pipes into the river.
Despite the plant’s hard work, concerns emerged
about high levels of bacteria, other pathogens, and
a wide range of synthetic contaminants entering the
St. Lawrence River, prompting officials to explore
solutions by the late 1990s. Luciano Paoloni, a
City of Montréal process engineer working on the
disinfection project, said ultraviolet disinfection was
considered but would have been logistically difficult
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WATER C AN ADA • M ARCH/APRIL 2025
Ville de Montréal
Saul Chernos is a freelance
writer for Water Canada.
COSTS:
Ozonation project:
Approved for $942 million (Currently on-budget).
Incineration conversion Project:
Estimate—$1.2 billion.
CONTRACTS / CONTRACTORS:
The main contractors for each of the two projects:
Ozonation project: Pomerleau and Groupe Deric.
Incineration conversion project:
Project not yet awarded.
WAT E R C A N A D A . N E T
