THE NUMEROUS IMPORTANT ISSUES FACING THE WATER INDUSTRY NOTWITHSTANDING, it is hardly hyperbole
to characterize PFAS as the defining water quality problem of this generation. With water systems across the
country actively contending with PFAS detections and many more likely to implement PFAS treatment in the
coming years, it is no longer accurate to label these compounds as emerging contaminants. In fact, they have
come to dominate the landscape of water quality issues, with PFAS-related abstracts representing about 20-25%
of the total submissions to the AWWA’s annual Water Quality Technology Conference for each of the past several years,
consistently surpassing those pertaining to lead and copper corrosion, which constitute another significant block. This
prevalence is typically a strong indication that a topic has progressed well-beyond fringe or emerging status to command
a robust share of attention and resources throughout the water sector.
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The attention is certainly warranted,
as PFAS are almost perfectly problematic:
Sources suggest that the PFAS family
is comprised of an estimated 5,000 to
10,000 compounds.
PFAS are employed in a very broad
range of applications, including a
myriad of widely used consumer
products.
Environmental occurrence of PFAS
has been reported across the globe,
including the most remote loca-tions
of the planet, along with both
groundwater and surface water sup-plies.
Various studies have identified PFAS
in the blood serum of almost every-one
tested, a problem compounded
by half-lives of some PFAS com-pounds
in the human body on the
order of years.
PFAS generally exhibit a high degree
of water solubility, rendering them
readily mobile in the water table and
hindering treatment efficacy.
Because the carbon-fluorine (C-F)
bonds characteristic of PFAS are
among the most stable in nature, the
compounds are nearly impervious
to microbial breakdown into benign
components.
These same strong C-F bonds confer
resistance to oxidation and advanced
oxidation, as well as thermal decom-position,
which requires uncom-monly
high temperatures.
Although reverse osmosis (RO)
has been demonstrated to achieve
very high rejection of most PFAS
compounds to which the technology
has been applied, management of
the PFAS-rich concentrate is a major
limitation.
Studies have shown chronic toxicity
with several PFAS species at very low
concentrations in drinking water, in
some cases at single-digit parts per
trillion (ng/L) levels.
As a result of this toxicity risk, the
associated maximum contaminant
levels (MCLs) in several states are in
the low ng/L range.
This unique combination of PFAS
ubiquity and toxicity, coupled with a high
profile in the mainstream media and the
resulting elevated consumer awareness,
has prompted many water utilities to im-plement
proactive treatment, even in the
absence of enforceable MCLs. In Califor-nia,
the impetus for such proactive treat-ment
is partly attributable to the very
low notification levels (NLs) for perfluo-rooctanoic
acid (PFOA) and perfluorooc-tane
sulfonate (PFOS) — two of the most
widely known and commonly occurring
PFAS compounds — of 5.1 and 6.5 ng/L,
respectively. (To date, Nevada does not
have routine PFAS monitoring require-ments
or actionable numeric regulatory
thresholds.) Moreover, the California
Division of Drinking Water has been
proactive in the permitting process for
PFAS treatment facilities, in some cases
obligating treatment with demonstrated
effectiveness to reduce concentrations to
below NLs. Unwilling to face the possi-bility
that the achievement of a particular
numeric value implies any satisfactory
level of PFAS contamination, many wa-ter
systems in California and around the
country are defaulting to a non-detect
(ND) treatment goal. Consequently, the
promulgation of MCLs is almost anticli-mactic;
the treatment may be costly, but
the best available technologies current-ly
in widespread use at municipal scale
— including granular activated carbon
(GAC), ion exchange (IX), and RO — are
well-understood, and the task is manage-able,
even if burdensome.
Removing detectable PFAS from
potable supplies, however, is not the end
game for water utilities. With parallels
to the ongoing pandemic, which has
PFAS CHALLENGES
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