WC134 JanFeb 2024 - Magazine - Page 13
Adoption of the MABR technology in Canada
Tackling N2O
Created as a by-product of the nitrification of ammonia, nitrous oxide
(N2O) is currently the largest contributor to stratospheric ozone depletion;
it has a global warming potential
approximately 300 times greater
than carbon dioxide (CO2). Only
the agriculture industry exceeds the
wastewater treatment sector in terms
of emissions of this harmful gas.
The MABR achieves simultaneous nitrification and denitrification
of ammonia within a single biofilm
and without the use of bubbles like
in conventional systems. Preliminary
data indicates that an MABR solution
may reduce N2O emissions by an
order of magnitude when compared
to traditional plants. Several detailed
academic studies are currently being conducted across multiple
geographies to quantify the specific benefits of MABR in terms
of N2O reduction.
Constructed in 1967, Elmira is a Class III wastewater
treatment plant that has benefited from process upgrades in
1983 and 2000. Servicing the town of Elmira (population of
approximately 12,000), the activated sludge plant uses tertiary
filtration and has a design flow of 7,800 m3/d and a daily peak
flow capacity of 19,500 m3/d.
The upgrade was needed due to high local levels of industrial
activity, meaning that the raw wastewater is of a high concentration, this combined with extreme wet weather flows meant
that effective secondary treatment capacity was limited. Space
limitations were one of the primary reasons for the specification
of MABR; the municipality needed a process intensification
solution that could be delivered without expanding the operational footprint of the plant as there is no space for additional
tankage.
Installed in the second anoxic zone of existing bioreactors,
the eight modules are intended to increase the secondary treatment capacity. There is scope and available tank volume to add
further modules to expand biological treatment capacity even
more, as and when it is required.
The MABR upgrade project was delivered by DuPont Water
Solutions with facilitation by local water and wastewater equipment specialist Aquafy Water Technologies Inc. Support for the
project was provided by engineering consultancy Jacobs and
construction contractor H2Ontario.
The MABR is gaining traction in Canada, as owners appreciate the considerable
benefits of the technology in assisting plant operations. The Region of Waterloo
in Ontario has been an early advocate for the use of MABR technology and in May
2023, eight OxyMem MABR modules from DuPont were installed at the Elmira
Wastewater Treatment Plant. This is the second operational MABR deployment at
the Region of Waterloo, representing a continuing and growing vote of confidence
in the technology.
“The Regional Municipality of Waterloo implemented membrane aerated
biofilm reactors (MABR) at the Elmira WWTP to address operational challenges
and capacity constraints posed by high strength industrial wastewater and high
peak flows due to inflow and infiltration in the collection system. OxyMem’s
OxyFAS membranes were installed, commissioned, and fully operational as of
June 2023. The Oxygen Transfer Rate (OTR) increased from 4-8 gO2/m2/d to
12-20 gO2/m2/d in three weeks following startup, indicating full establishment
of the biofilm. There is a strong correlation between the steady state OTR and the
influent loading rate. The DuPont OxyMem MABR has been exceeding performance
targets as observed nitrification rates (NR) range from 2-4 gN/m2/d.” Courtesy of
Region of Waterloo and Jacobs.
while, MABR installations in Canada and European countries
have noted that increased water flows did not result in the loss
of biomass because of the biofilm being securely attached to the
membranes within the module.
A modular solution
As an inherently modular solution, the MABR provides excellent
flexibility and easy incremental expansion for plant owners, being able to expand biological treatment in response to changing
demand. The modules can be used to quickly expand treatment
capacity, often without any interruption to plant operations; this
is a considerable benefit compared to conventional technologies
or alternate means of upgrade such as SBR and MBBR, which
may require extensive reworking of civils or existing systems to
facilitate a plant conversion.
At most plants, there is no need for diverting flows, over
pumping, or draining of tanks—modules are lowered into existing treatment basins without interruption to operations or the
need for confined space entry, helping keep personnel safe. The
physical deployment of a module is completed within a matter of
hours rather than weeks or months for other technologies, once
the receiving steelwork has been located.
Furthermore, the MABR modules can be removed at any time
for any reason, reverting the plant to its previous state. This gives
operators flexibility in terms of management of their assets as
modules can be redeployed to help manage peaks in demand at
different locations, while also shifting the burden of risk onto the
module provider.
WAT E R C A N A D A . N E T
WATER C AN ADA • JANUARY/ FEBRUARY 2024
13
