Water & Wastewater Asia January/February 2023

SINGAPORE FOCUS
Fig. 2: Performance
of NanoPure
membrane for
hardness removal
(left) and its
application for
drinking water
treatment (24 m 3 /
day) in Myanmar
(right)
chlorine can prevent the membrane
According to the World Health
provides one-step direct treatment of
from bacteria growth to mitigate
Organization, water with hardness of
surface water for hardness reduction.
the biofouling issue that commonly
more than 120ppm is defined as hard
The membrane was tested with a
occurs in the spiral-wound membrane
water and the hardness of drinking
feed solution of 300ppm MgSO4 at
module. The chemical stability of the
water is an important consideration
50% recovery and two-bar operating
NanoPure membrane over the pH range
for healthy lifestyle and economical
pressure. A stable membrane
of 0-14 enables handling of acidic and
system operation. There are several
performance was observed with an
caustic wastewater without worrying
techniques available to reduce
average 85-90% MgSO4 removal over
about disintegration of the membrane
the hardness in water and among
the two months’ operation (Fig. 2),
structure.
them, membrane filtration and water
bringing down the concentration from
softening are the popular solutions in
300ppm to approximately 30-45ppm,
With the above-mentioned membrane
drinking water treatment.
which is within the range of soft water
features, the NanoPure NF membrane
less than 60ppm for potable usage.
can be applied for various water and
wastewater treatment applications.
These applications include, but not
limited to, water softening for drinking
water, industrial wastewater treatment
In comparison with water softening
process, membrane filtration process
produces less waste with easier
system operation and maintenance.
As such, NanoPure membrane system
Textile wastewater treatment:
Colour removal
Removal of colour and organic content
of wastewater in textile industry
Fig. 3: Colour
removal using
NanoPure membrane
for organic and colour removal, pretreatment
for seawater RO with a higher
recovery, acidic and caustic resource
recovery from industrial processes, etc.
The following paragraphs showcase
several recent case studies with the
NanoPure membranes.
Drinking water treatment: Hardness
removal
In drinking water treatment process,
hardness removal (predominantly
calcium and magnesium cations) is
often required because excessive
hardness in the drinking water will
cause undesired scaling and corrosion
issues in the water distribution system,
while exposure to hard water may
cause skin irritation and potentially
eczema.
12 WATER & WASTEWATER ASIA | JANUARY/FEBRUARY 2023