Chemical Engineering May 2023 - 31

or time.
Laboratory column testing. Small
column testing can be performed at
bench scale to simulate the longerterm
performance of a full-scale
system. Two common methods
include the Rapid Small-Scale Column
Test (RSSCT) and Accelerated
Column Test (ACT), where GAC is
carefully resized to a determined
smaller particle size, allowing for the
simulation of months of full-scale
system run time in just days. Laboratory
column testing can be more
reliable than isotherms and can provide
better details about component
breakthrough order and estimated
days until breakthrough.
Pilot systems. Pilot systems consist
of small vessels located onsite at
the application, treating a slipstream
or representative sample of the target
source stream. Pilots can be
designed to more closely replicate
the conditions of a full-scale system
and, coupled with representative
pretreatment, are the most reliable
method for determining full-scale
system performance.
Some GAC and equipment vendors
offer rental equipment, which
includes carbon-exchange services,
including removal of spent
GAC from the vessel, disposal and
replacement with fresh GAC. Rental
units can be particularly good options
for pilot systems, and some
rental equipment units are designed
so that the entire unit can be returned
to the provider for carbon
reactivation or disposal, simplifying
media exchange.
Safety
Activated carbon is generally a safe
technology, especially when used in
well-designed systems. However,
there are a few safety considerations
that are worth highlighting.
Wet activated carbon preferentially
removes oxygen from air. In
closed or partially closed containers
and vessels, oxygen depletion may
reach hazardous levels.
If workers
are to enter a vessel containing
carbon, appropriate sampling and
work procedures for potentially lowoxygen
spaces should be followed,
including all applicable federal and
state requirements.
In vapor-phase applications, high
concentrations of VOCs and some
reactive components can cause
the temperature within a carbon
bed to increase. Heating may be
controlled by diluting the inlet
air
with nitrogen or by pre-wetting the
carbon. Concentrations of gases
should be kept to below 25% of the
lower explosive limit (LEL). Seeking
input and advice from an activated
carbon supplier for applications
involving high concentrations of
organic compounds or potentially
reactive species (certain ketones,
aldehydes and carboxylic acids) is
highly recommended.
■
Edited by Mary Page Bailey
Reference
1. DiStefano, R., others, Thermal destruction of PFAS
during full-scale reactivation of PFAS-laden granular
activated carbon, Remediation, Vol. 32, Issue 4, September
2022.
All images provided by Calgon Carbon Corp.
Authors
Martin
Drive,
O'Brien
Moon
(3000
Township,
GSK
PA
15108; Email: martin.obrien@
kuraray.com) is a technical marketing
manager at Calgon Carbon
Corp. He leads initiatives
related to PFAS removal, remediation
and gas processing in
industrial applications using activated
carbon.
He previously
served as an applications engineer at Calgon Carbon,
supporting the use of activated carbon in industrial
applications. He received a B.S. in chemistry from
Case Western Reserve University.
Rebecca DiStefano (Same address
as above; Email: rebecca.
distefano@kuraray.com) is a
senior applications engineer at
Calgon Carbon Corp. in the Industrial
Solutions and Diversified
Applications business unit.
Prior to this position, she served
as senior group leader of carbon
applications and testing,
overseeing testing to evaluate carbon performance
for PFAS removal. She received her B.S.Ch.E from
The Pennsylvania State University, and her M.B.A.
from Robert Morris University.
Andrew Harris (Same address
as above; andrew.harris@kuraray.
com) is a senior applications
engineer with Calgon Carbon
Corp. He is a licensed professional
engineer in Wisconsin
with 24 years of experience in
the environmental industry. He
is responsible for assisting consultants
and end users with the
evaluation and selection of optimal activated carbon
products for various applications. He graduated from
the University of Wisconsin-Madison with a B.S. in
mechanical engineering and an M.S. degree in
environmental engineering.
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