Chemical Engineering June 2022 - 14

SUEZ Water Technology & Solutions
FIGURE 3. SUEZ is developing spiral-wound elements that
are more resistant to high temperatures, pH levels and
higher pressures
production of green H2.
Evonik has developed a new anion-exchange
membrane (AEM),
which should contribute to the
breakthrough of electrolytic production
of H2. " Electrolysis featuring
anion-exchange membranes has
benefits over other electrolytic processes
such as conventional alkaline
electrolysis using diaphragms (AEL)
or the more recent method of proton
exchange membrane electrolysis
(PEM), which is dependent on raw
materials such as precious metals.
" Because the anion-conducting
membranes work in a caustic versus
acidic environment, standard 316
stainless steel can be used in the
electrolyzer, " says Baumgarten. " In
PEM electrolyzers, precious metalplated
and rare-earth metals are
needed, the expense of which could
limit the future of a H2 economy. This
development featuring our anion
conducting membrane systems will
be launched next year and move us
closer to a H2 economy. "
Likewise, the trend toward sustainability
regarding water conservation
and reuse is driving the need
for membranes that can withstand
higher temperatures and pressures.
" As chemical and other processors
try to conserve water, they are wanting
to reuse water that traditionally
would have been sent to treatment
facilities, " says Erik Hanson, director
of global product management and
strategy, with SUEZ Water Technology
& Solutions (Trevose, Pa.; www.
suezwatertechnologies.com). " Traditionally
reverse osmosis (RO) and
nanofiltration (NF) have been used for
many years for treating water coming
into plants and existing membranes
worked well for those applications.
14
But when you are using water
that has gone through one or
more industrial processes, it
has things in it that are perhaps
less predictable than
what you find in intake water,
so in reuse and zero-liquiddischarge
(ZLD) applications,
we are seeing more innovation
in membrane technologies
to enable these separation
processes.
" This type of water might
have more extreme pH or
the temperature might be higher
than what you would start with in a
typical RO treatment, so today's parameters
are taking us beyond what
the RO elements of a decade ago
would be able to handle, " continues
Hanson. " There is a lot of innovation
for spiral-wound elements that are
making them more resistant to high
temperatures, pH levels and higher
pressures " (Figure 3).
For example, as salt concentrahigher
and processors
tions
get
need to operate at higher pressures
to recover those salts, SUEZ's Industrial
RO 5, RO 6 and RO 7 elements
can be used. " These elements are
made with special membranes and
special element construction to provide
high rejection of salt at higherthan-average
brine
other
cases,
concentrations
and pressures, " says Hanson.
In
industrial processes
may make water acidic. Purifying
or concentrating those acids
requires a membrane element that
can be continuously operated at low
pH. " Our Duracid membrane element
can continually operate in the
2 to 3 pH range, helping processors
reuse water without having to do a
lot of pH adjustment prior to treatment, "
Hanson continues. " If you
didn't have an element like this and
you wanted to purify an acid stream
to enable water reuse, you would first
have to neutralize it, which means
adding a lot of caustic at a significant
expense. The development of
a membrane that can operate at low
pH avoids that neutralization, saving
time and expense. "
Overcoming fouling
Since fouling and scaling have long
been a major challenge with membranes,
several manufacturers are
working on improvements that will
help processors reduce their environmental
footprint and often enable
the use of membranes in applications
where it may not have been
previously possible.
" Fouling is one of the most common
and severe problems in the operation
of RO systems. Unchecked,
it causes significant operational
problems such as frequent interruption,
damage to the membranes, intense
chemical and energy use and
regular cleaning-in-place of the RO
and the pressure exchangers, " says
Tina Arrowood, principal research
scientist with DuPont Water Solutions
(Edina, Minn.; www.dupont
watersolutions.com). " The bottom
line is far less water produced for
the money operators spend on capital
assets and operations. "
The company is currently producAqua
Membranes
FIGURE 4. The Aqua Membranes product features a customized 3D-printed pattern on the membrane to
reduce fouling and wasted pressure
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JUNE 2022

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Chemical Engineering June 2022

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