Chemical Engineering April 2020 - 42

Feature Report
High-Purity Water Simplified
There are a number of process technologies available to meet the strict standards for
high-purity water in different industrial sectors
Jeff Holland,
Rich Jarrett
and Alan Knapp
Evoqua Water
Technologies
IN BRIEF
PURIFYING WATER FOR
INDUSTRIAL USE
PHARMACEUTICALS AND
PERSONAL CARE
MEDICAL INDUSTRY
MICROELECTRONICS
THE RAMIFICATIONS OF
WATER IMPURITY
SERVICING A UPW
SYSTEM
I
t is easy to think that
the water coming out
of our faucets can be
used anywhere. Although
potable water
provided by a municipality
is treated and held to
specific safety and health
standards, it often contains
impurities that can
have a significant impact
on certain manufacturing
processes and end
products (Figure 1). This
article reviews how water
is purified
use, why high-purity water
is needed in different
for industrial
FIGURE 1. Many industrial processes demand water of higher purity than what is typically
provided by municipalities, so additional treatment steps are often required
markets and how to maintain water quality
over time.
Purifying water for industrial use
There are a variety of systems and methods
available to achieve differing degrees of water
purification. Some methods are simple, such
as media or carbon filtration, while other systems
are far more complex, such as reverse
osmosis and ultrafiltration. Typical components
of a water purification system include
the following:
* Activated carbon - Water is filtered
through carbon to remove organic material
and chlorine
* Particle filtration - Water is filtered through
a physical barrier, removing fine particles
and microorganisms
* Reverse osmosis (RO) - Water is forced
through a semi-permeable membrane in
the opposite direction of the natural flow
with enough force to exceed the osmotic
pressure, rejecting dissolved solids
* Ion exchange (IX) - Resins remove ionic
impurities from water and are regenerated
through a reversible chemical process
* Electrodeionization (EDI) - Combines ion
exchange and ion-selective membranes
42
with direct current to remove ionic impurities
without the need for acids and
caustic chemicals
* Ultraviolet (UV) light - Organic carbon reduction,
bacteria, viruses and protozoa are
exposed to UV light, damaging their DNA
and rendering them inactive
* Ultrafiltration (UF) - Membrane filters remove
extremely small particles, bacteria
and pathogens
Different industries have specific regulations
to follow in order to ensure ultrapure
water meets their needs. Because each
application is unique, a water purification
system may include a single technology, or
a combination of multiple technologies to
achieve optimal results.
Pharmaceuticals and personal care
In the pharmaceutical and personal care
markets, high-purity water regulations are
defined by the United States Pharmacopeia
(USP; Rockville, Md.; www.usp.org) and
equivalent organizations in other parts of
the world. The USP provides minimum standards
around ionic and organic chemical
purity and microbial contamination to protect
the health and safety of consumers using the
CHEMICAL ENGINEERING WWW.CHEMENGONLINE.COM
APRIL 2020
http://www.usp.org http://WWW.CHEMENGONLINE.COM
Chemical Engineering April 2020

Table of Contents for the Digital Edition of Chemical Engineering April 2020
