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supply (Water Quality) regulations 2010, and
it has also been tested by many other water
treatment authorities and laboratories.
DMI-65 does not actually remove the arsenic,
but rather it relies on the fact that arsenic and
iron readily form a complex, and when the
media takes out the iron, it takes the arsenic
with it. DMI-65 promotes the highest oxidation
rate of any catalytic filtration media to achieve
the removal of dissolved iron to almost
undetectable levels, as low as 0.005 ppm. In
the correct operating conditions, arsenic will
also be removed to well below guidelines.
High flow rates
The infused technology of DMI-65 promotes the
highest oxidation rate of any catalytic filtration
media. This permits a significantly higher water
flow rate to achieve the same level of iron and
manganese removal. DMI-65 can operate
at linear filtration velocities up to twice that
of conventional media, with a corresponding
reduction in capital equipment costs.
High load capacity
Because of the increased surface area of
the micro-porous structure of the matrix
material, the DMI-65 also has higher iron
and manganese load capacity, which can
extend the duration of filter runs and the time
between backwashing, thereby reducing
downtime, operating expense and wastage.
The total cost of the arsenic removal water
filtration system is significantly less than
alternative solutions. The effectiveness, but
relative simplicity, of DMI-65-based systems
reduces the up-front capital expenditure
on plant complexity, as well as the ongoing
operational expenditure in chemicals, power
and backwash wastewater recovery.
Regeneration not required
The media operates with a continuous
injection of sodium hypochlorite at low residual
levels (0.1 to 0.3 ppm), which eliminates the
need for potassium permanganate.
Mareeba Shire Council engaged Amiad
Water Systems to design, construct and
commission a 6–10-litres-per-second
arsenic filtration plant for the township of
Chillagoe, in Far North Queensland. The
town sources its water from a local bore
field, which suffers from arsenic levels in
the range of 0.010–0.020 milligrams per
litre – exceeding the Australian Drinking
Water Guidelines. The contract specified
that the plant must achieve a target level of
arsenic of less than 0.005 milligrams per
litre in the product water.
To achieve the target, Amiad proposed
a system of chlorination, ferric chloride
dosing, DMI-65 catalytic media filtration
and cartridge filter polishing. The supplied
plant is fully automatic, and is controlled
by an Allen Bradley PLC with a
Schneider PC / touch screen loaded with
Citect Software, for local and remote operation.
Chlorination: In groundwater, arsenic
occurs predominantly as arsenite As (III),
and requires conversion to arsenate
As (V) by chlorination to enhance the
effectiveness of the filtration process.
Chlorine also acts as a catalyst for the
DMI-65 media, and is required for its
regeneration to re-establish the oxidising
environment on the surface of the media.
Ferric chloride dosing: Arsenic can
bond with iron salts in the water, and
with metal-based coagulants, such as
ferric chloride. Ferric chloride is dosed
such that there is a sufficient reservoir of
iron for arsenic to form complexes and
precipitants with the iron salts via the
chemical processes of precipitation, co-
precipitation and adsorption, which can
then be filtered.
DMI65 catalytic media filtration:
DMI-65 is a manganese dioxide-infused
media, whose surface acts as a good oxidant
and is effective in removing both arsenite and
arsenate, as well as iron/arsenic complexes
and precipitants. The DMI-65 media filters are
periodically backwashed and rinsed, based on
either pressure differential across the media
filters or time, whichever occurs first.
Cartridge filters: One-micron cartridge
filters were installed to polish the product
water and provide a final barrier to the
The arsenic filtration plant, designed and
constructed by Amiad utilising DMI-65
media, was commissioned in March 2015,
and has been successfully reducing the
arsenic to 0.001 milligrams per litre,
making it suitable for consumption by the
community of Chillagoe, Queensland.
Case study: Chillagoe Arsenic Filtration Plant
330867E_Quantum Filtration I 2222.indd 2
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