Water & Wastewater Asia September/October 2021

WATER & WASTEWATER ASIA | SEPTEMBER/OCTOBER 2021
What are the advantages of using
an EDI module for continuous
operation?
Scheu: There are many. For one,
plants can operate 24/7. Because,
unlike conventional mixed-bed ion
exchangers, regeneration of the resins
here uses electrical energy instead
of acids and caustic chemicals –
and it occurs continuously during
production. By contrast, if plant
operators wanted to run a conventional
mixed-bed exchanger around the
clock, they would need at least two
systems to bridge the regeneration
cycles.
Also, as long as the feed water
doesn’t exceed the maximum values,
the EDI module can be connected
immediately downstream of the first
RO system. Thus, no additional highpressure
pump is needed as would
be the case when connecting two RO
modules. The great advantage there
is that it saves energy. In our project,
energy consumption in the EDI stage
for the MPure36 – SB developed in
collaboration with MEGA comes to
0.088kW/m 3 .
Which beverage producers might
want to consider integrating EDI?
Scheu: An additional EDI module
makes sense wherever the quality
of the raw water tends to fluctuate.
This is especially important when
producing still table water, where the
mineral composition of the water must
not deviate from the figures printed
on the label by more than 20%.
When the content of the raw water
itself already varies by +/-15% before
remineralisation, there’s very little
wiggle room for adding minerals back.
EDI eliminates these variations. With
it, the water is always demineralised
to the same degree, and the quality
of the treated water is therefore
independent of the water coming
from the RO system. When adding
minerals afterward, the dosing can
be kept closer to the minimum, thus
saving costs on the rather expensive
minerals. It saves on raw materials.
In other words, the same amount
of minerals can yield more product.
Thus, using an EDI module can
reduce consumption of the expensive,
ultrapure minerals used to make table
water by 5-10%.
EDI can also be of interest to
producers of alkaline water. Here, too,
the consistent quality and resulting pH
value of 7 provide the perfect basis for
then producing water with a pH of 9,
which is becoming increasing popular.
What outputs can be achieved by
combining Hydronomic and EDI?
Scheu: EDI can cover the same
operation as the Hydronomic. It can
treat up to 120m 3 of water per hour,
with the option of variable product
volumes. The system is always
precisely calibrated to the quality of
the raw water and the requirements of
the final product.
The water treatment solution
developed for Makkah Water is one of
the biggest Krones has built to date.
It operates at up to 3x110m 3 of water
per hour, and is therefore around three
times the size of our conventional
Hydronomic systems.
EDI can also be of interest to
producers of alkaline water. Here,
too, the consistent quality and
resulting pH value of 7 provide the
perfect basis for then producing
water with a pH of 9, which
is becoming increasing
popular.
Dirk Scheu
Sales Specialists for Water Treatment
Solutions, Krones
Hydronomic water
treatment system
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