Iron and manganese removal systems installed at two provincial parks
By Ahron Nahmias,P.Eng
Emily Provincial Park filtration system utilizes two parallel trains (Macrolite media and
activated carbon filters), with 18-50 GPM per train at 60-100 PSI.
In order to meet the current drinking
water regulation (Regulation
170/03) for a groundwater source
under the direct influence of surface
water, some of the provincial parks
in Ontario were required to upgrade
their drinking water purification plants.
Responding to this challenge,
Metcon conducted pilot studies at two
sites, specifically addressing the need
for iron and manganese removal systems
with an effective filtration system.
The goal was to bring iron and manganese
levels below the MOE’s aesthetic
objective guidelines in a cost effective
manner without adding any special
iron removal filters for the job.
Pilot studies were conducted at
Emily Provincial Park and Long Point
Provincial Park for testing the efficiency
of Macrolite media for iron and
manganese removal after oxidation.
Sodium hypochlorite, which is also an
oxidant as well as the most common
disinfectant, was used to study oxidation
and subsequent filtration of iron
and manganese by the filter media.
Manganese behavior in well water
varies and sometimes it is oxidized easily
by NaOCl only; however at times it
may require a stronger oxidant like
potassium permanganate (KMnO4) or
hydrogen peroxide (H2O2) to achieve
desired levels of oxidation.
The pilot system installed at the
sites included 40/60 mesh Macrolite
ceramic media filters (one working and
one standby) for turbidity, iron and
manganese removal. This was followed
by a 12/40 mesh activated carbon
media filter to control trihalomethanes
(THM), taste and odour issues. The
pilot system also included chemical
feed systems for polymer coagulant,
NaOCl and KMnO4 feed, upflow contact
tanks, and a bench scale analyzer
for on-site measurement of treated
water quality parameters.
The system operated for a week
with an average run time of 6 hours per day and treated water parameters
including turbidity, pH, free chlorine,
total chlorine, iron and manganese levels
were tested and recorded every 2
hours. It was run at various oxidant
dosing levels in order to determine the optimized treatment strategy.
Results showed turbidity levels in
treated water of 0.0 NTU consistently
during the whole operation. 100% turbidity
removal was achieved with the
aid of on-line polymer coagulant dosing.
Iron was easily oxidized by NaOCl
only and efficiently removed by the
Macrolite media filter bed, allowing for
treated water iron levels recorded in the
range of 0.00 to 0.02 mg/l. Manganese
removal could not be achieved down to
the desired level using only NaOCl as
the oxidizing agent. However a combination
of 3 mg/l of NaOCl feed and 0.14 mg/l of KMnO4 feed yielded
treated water with a manganese level of
0.024 mg/l. No THM formation was
observed during the whole process.
Treated water samples were sent to
SGS Lakefield for testing and found
consistent with on-site testing.
The studies established the efficiency
of Macrolite media for iron and
manganese removal from well water.
Superior turbidity, iron and manganese
removal rates were successfully
achieved by only using approximately
12 minutes of contact time for oxidation.
Based on the study data, full-scale
systems were installed at both sites to
meet the desired removal levels of iron,
manganese, turbidity and pathogens.
With minimal monitoring and human
intervention, both systems continue to
supply safe drinking water that meet
and exceed regulations.
Ahron Nahmias is with Metcon Sales
and Engineering Limited
Contact: ahronn@metconeng.com
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