Ontario Pipeline - Summer 2017 - 31

will provide information on the legislation,
explore opportunities to optimize treatment and give advice on putting together
an action plan.

Cyanotoxin: Microcystins
Certain strains of cyanobacteria (e.g.
microcystis, oscillatoria) produce cyanotoxins, and the most commonly detected
cyanotoxins in Ontario are microcystins
(MC). Microcystins are commonly known
as hepatotoxins and capable of causing
cell damage to the liver and subsequently
to the kidneys (McLellan and Manderville,
2017). In a newly-formed algae bloom,
about 70 per cent of the microcystins
is contained within cyanobacterial cells
(i.e. intracellular or cell-bound); while the
remaining fraction is dissolved in the water
column (i.e. extracellular) (see Figure 2). As
a bloom breaks down, more of the intracellular microcystins become dissolved and
can persist for more than two weeks in
the surface water, even after a bloom is
no longer visible.

Legislation
Legislation related to cyanotoxins in
water in Canada are based on microcystins concentrations. There are numerous
variants of microcystins, but MC-LR is
most commonly detected (named after
the leucine and arginine amino acids in
its chemical structure). The Health Canada
Guideline for Canadian Drinking Water
Quality (GCDWQ) is a maximum acceptable concentration (MAC) of 1.5 µg/L of
total microcystins (all measurable variants),
while the Ontario Drinking Water Quality
Standard (ODWQS) is a MAC of 1.5 µg/L of
MC-LR (Health Canada, 2016; SDWA, 2002).
These limits are considered protective of
adults and infants. Other cyanotoxins,
such as anatoxin-a, cylindrospermopsin
and saxitoxin, have not been regulated in
Canada due to a lack of available health
and treatment data.
The most cost-effective strategy for the
prevention of algae blooms starts with
source water protection and substantial
reductions in nutrient input into surface
waters. Effective management for cyanotoxins in drinking water requires the application of the multiple-barrier approach:

Figure 2. Examples of cyanobacteria in
a harmful algae bloom in Lake Erie, and
differentiation of intracellular and extracellular
forms of cyanotoxins such as microcystins.

A SOUND ACTION PLAN SHOULD INCLUDE
PROCEDURES FOR MONITORING, RESPONSE ACTIONS
FOR DURING AND AFTER A BLOOM, AS WELL AS
MEASURES FOR ISSUING PUBLIC NOTICES.
1)
2)
3)
4)

Source Water Protection
Treatment
Monitoring and Compliance
Community Involvement

Treatment
Removal of microcystins from raw
water requires a combination of chemical,
physical and/or biological processes due
to the nature of microcystins being present as both intracellular and extracellular
(see Figure 3). Fortunately, the treatment
(i.e. removal and destruction) of intracellular and extracellular microcystins can be
achieved with optimized performance of
conventional drinking water treatment
systems to achieve about 99.99 per cent
reductions of MC-LR. It is recommended to
provide the removal of cell-bound microcystins prior to the removal of dissolved
microcystins, as downstream oxidation
processes (e.g. chlorination) could cause
cyanobacterial cells to rupture and increase
the dissolved concentration of microcystins.
In general, coagulation processes can
achieve 60 to 99 per cent removal of intracellular microcystins by optimizing chemical doses and pH for the removal of natural
organic matter (NOM). This may require
operation at a reduced pH and increased

or adjusted chemical uses during warmer
months. It should be noted that cyanobacterial cells can accumulate in the sediment
of clarifiers and lead to increased dissolved
concentrations of microcystins; therefore,
the frequency of sludge removal could be
increased during a bloom. Biological filtration can also be effective at removing
cell-bound microcystins, and membrane
filtration can remove more than 90 percent
of microcystins if deemed necessary to meet
other treatment standards.
Chlorination can be optimized for the
destruction of dissolved microcystins by
ensuring a minimum contact time of 30 min
at a dose of greater than 1 mg/L (ppm) at a
pH less than 8, as lower pH values enhance
oxidation of microcystins by chlorination. It
is not recommended to increase chlorine
dosing for the treatment of cyanotoxins
to minimize formation of disinfection byproducts. The efficiency of coagulation and
chlorination can be optimized at bench-scale
with site-specific water to provide an indication of the performance of these processes
during a bloom. Ozonation can be highly
effective for the destruction of both intracellular and extracellular microcystins; though
the destruction of cell-bound microcystins
is dependent on dose and contact time.

O N T A R I O P I P E L I N E | SUMMER 2017 | 31



Table of Contents for the Digital Edition of Ontario Pipeline - Summer 2017

From the Publications Chair
OWWA President’s Message
The OMWA Report
The OWWEA Report
From Our AWWA Director
Niagara Falls Success!
Conference Sponsors
2017 Fuller Award
2017 OWWA Awards
Silver Water Drop
Water Efficiency Awards
OMWA Awards
OMWA Board of Directors and Executive Committee, 2017
Committee Reports
Harmful Algae Blooms: Management of Cyanotoxins in Drinking Water Treatment
OWWEA Member Listing
OWWEA Member News
Index of Advertisers | Ad.com
Ontario Pipeline - Summer 2017 - Intro
Ontario Pipeline - Summer 2017 - bellyband1
Ontario Pipeline - Summer 2017 - bellyband2
Ontario Pipeline - Summer 2017 - cover1
Ontario Pipeline - Summer 2017 - cover2
Ontario Pipeline - Summer 2017 - 3
Ontario Pipeline - Summer 2017 - 4
Ontario Pipeline - Summer 2017 - 5
Ontario Pipeline - Summer 2017 - 6
Ontario Pipeline - Summer 2017 - From the Publications Chair
Ontario Pipeline - Summer 2017 - 8
Ontario Pipeline - Summer 2017 - OWWA President’s Message
Ontario Pipeline - Summer 2017 - The OMWA Report
Ontario Pipeline - Summer 2017 - The OWWEA Report
Ontario Pipeline - Summer 2017 - 12
Ontario Pipeline - Summer 2017 - From Our AWWA Director
Ontario Pipeline - Summer 2017 - Niagara Falls Success!
Ontario Pipeline - Summer 2017 - 15
Ontario Pipeline - Summer 2017 - 16
Ontario Pipeline - Summer 2017 - Conference Sponsors
Ontario Pipeline - Summer 2017 - 2017 Fuller Award
Ontario Pipeline - Summer 2017 - 2017 OWWA Awards
Ontario Pipeline - Summer 2017 - 20
Ontario Pipeline - Summer 2017 - 21
Ontario Pipeline - Summer 2017 - Silver Water Drop
Ontario Pipeline - Summer 2017 - Water Efficiency Awards
Ontario Pipeline - Summer 2017 - OMWA Awards
Ontario Pipeline - Summer 2017 - 25
Ontario Pipeline - Summer 2017 - OMWA Board of Directors and Executive Committee, 2017
Ontario Pipeline - Summer 2017 - Committee Reports
Ontario Pipeline - Summer 2017 - 28
Ontario Pipeline - Summer 2017 - 29
Ontario Pipeline - Summer 2017 - Harmful Algae Blooms: Management of Cyanotoxins in Drinking Water Treatment
Ontario Pipeline - Summer 2017 - 31
Ontario Pipeline - Summer 2017 - 32
Ontario Pipeline - Summer 2017 - OWWEA Member Listing
Ontario Pipeline - Summer 2017 - 34
Ontario Pipeline - Summer 2017 - 35
Ontario Pipeline - Summer 2017 - 36
Ontario Pipeline - Summer 2017 - OWWEA Member News
Ontario Pipeline - Summer 2017 - Index of Advertisers | Ad.com
Ontario Pipeline - Summer 2017 - cover3
Ontario Pipeline - Summer 2017 - cover4
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