Document ID: EPA-HQ-OPPT-2002-0066-0007
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2002-05-05T04:00Z

Office
of
Pesticide
Programs
Science
Policy
The
Incorporation
of
Water
Treatment
Effects
on
Pesticide
Removal
and
Transformations
in
Food
Quality
Protection
Act
(
FQPA)
Drinking
Water
Assessments
October
25,
2001
Office
of
Pesticide
Programs
United
States
Environmental
Protection
Agency
Washington,
D.
C.
20460
Table
of
Contents
Executive
Summary.
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4
1.0
Introduction
...............................................................
5
2.0
Science
Policy
and
Procedure
for
Incorporating
Water
Treatment
into
FQPA
Drinking
Water
Assessments
......................................................
7
2.1
Policy
Development
Process
............................................
7
2.2
Policy
for
Considering
Water
Treatment
in
FQPA
Drinking
Water
Assessments
...
8
2.3
Evaluation
of
the
Water
Treatment
Data.
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.
10
3.0
Literature
Review
of
the
Impacts
of
Water
Treatment
on
Pesticide
Removal
and
Transformations
in
Drinking
Water
........................................
11
3.1
Overview
..........................................................
11
3.1(
a)
Summary
of
the
Impact
of
Water
Treatment
on
Pesticide
Removal
and
Transformation
3.2
Background........................................................
12
3.3
Technical
Approach
in
Assessing
Water
Treatment
Data
....................
12
3.4
Regulatory
History
..................................................
13
3.4(
a)
Pesticides
Currently
Regulated
Under
the
SDWA
3.5
Water
System
Statistics
..............................................
14
3.5(
a)
Population
Served
(
Size
of
Water
Treatment
Facilities)
3.5(
b)
Types
of
Water
Treatment
Associated
with
Different
Source
Waters
3.6
Water
Treatment
Assessment
Techniques
................................
17
3.7
Water
Treatment
Processes
and
Removal
Efficiencies
......................
18
3.7(
a)
Conventional
Treatment
......................................
18
3.7(
a)
1
Coagulation/
Flocculation
3.7(
a)
2
Softening
3.7(
a)
3
Sedimentation
3.7(
a)
4
Filtration
3.7(
b)
Disinfection/
Chemical
Oxidation...............................
22
3.7(
c)
Carbon
Adsorption
..........................................
25
3.7(
c)
1
Powdered
Activated
Carbon
(
PAC)
3.7(
c)
2
Granular
Activated
Carbon
(
GAC)
3.7(
c)
3
Biologically
Active
Carbon
(
BAC)
3.7(
d)
Membrane
Treatment
........................................
29
3.7(
d)
1
Reverse
Osmosis
(
RO)
3.7(
d)
2
Ultrafiltration
(
UF)
3.7(
d)
3
Nanofiltraton
(
NF)
3.7(
e)
Corrosion
Control
Treatments
.................................
32
3.7(
f)
Aeration/
Air
Stripping
.......................................
32
2
3.8
Pesticide
Transformation
Associated
with
Certain
Treatment
Processes
.........
33
3.8(
a)
Transformation
Induced
by
Lime
Softening
3.8(
b)
Transformation
Caused
by
Chemical
Disinfection/
Oxidation
3.8(
b)
1
Chlorination
Byproducts
3.8(
b)
2
Ozonation
Byproducts
3.9
Assessment
of
the
Relationship
Between
Environmental
Fate
Properties
and
Water
Treatment
Effects
.................................................
37
3.10
Acknowledgments..................................................
40
3.11
Literature
Cited....................................................
40
Appendix
A.
Removal
of
Pesticides
Using
Different
Reverse
Osmosis
Membranes
.........
44
Appendix
B.
Questions
for
Public
Comment
.......................................
48
3
Executive
Summary
The
Food
Quality
Protection
Act
of
1996
(
FQPA)
requires
that
all
tolerances
for
pesticide
chemical
residues
in
or
on
food
consider
anticipated
dietary
exposure
and
all
other
exposures
for
which
there
is
reliable
information.
Drinking
water
is
considered
a
potential
pathway
of
dietary
exposure
to
pesticides.
Because
drinking
water
for
a
large
percentage
of
the
population
is
derived
from
public
water
systems
which
normally
treat
raw
water
prior
to
consumption,
the
impact
of
water
treatment
on
pesticide
removal
and
transformation
should
be
considered
in
drinking
water
exposure
for
risk
assessments
completed
under
FQPA.
Treated
drinking
water
for
the
purpose
of
FQPA
exposure
assessment
will
be
defined
as
ambient
ground
or
surface
water
which
is
either
chemically
or
physically
altered
using
technology
prior
to
human
consumption.
Therefore,
the
objectives
of
this
science
policy
paper
are
to:
1)
present
a
preliminary
literature
review
on
the
impact
of
different
treatment
processes
on
pesticide
removal
and
transformation
in
treated
drinking
water
derived
from
ground
and
surface
water
sources;
and
2)
describe
how
the
Office
of
Pesticide
Programs
(
OPP)
will
consider
the
impacts
of
drinking
water
treatment
in
drinking
water
exposure
assessments
under
FQPA.

Literature
Review
A
wide
variety
of
factors
are
taken
into
account
to
assess
the
impact
of
drinking
water
treatment
on
the
levels
of
different
pesticides
in
drinking
water.
It
is
important
to
note
that
a
sizeable
proportion
of
the
nation,
approximately
23
million
people,
obtain
their
drinking
water
from
private
wells
and
other
sources
that
undergo
no
treatment.
For
those
drinking
water
sources
that
are
treated,
available
survey
information
establishes
that
there
are
many
distinct
types
of
water
treatment
processes
(
and
many
more
combinations
of
processes)
in
use
throughout
the
United
States.
Nearly
all
public
water
supply
systems
use
some
form
of
disinfection,
and
a
series
of
conventional
treatment
processes
(
coagulation­
flocculation,
sedimentation,
and
filtration).
The
processes
that
appear
to
have
the
most
impact
on
pesticide
removal
 
granular
activated
carbon
(
GAC)
and
powdered
activated
carbon
(
PAC)
 
are
commonly
found
or
used
in
larger
water
supply
systems
but,
because
of
high
costs,
are
rarely
used
by
the
smallest
systems.
Other
methods,
such
as
 
softening ,
reverse
osmosis,
and
air
stripping
are
also
less
frequently
used
to
remediate
water
quality
concerns.
In
sum,
there
is
enormous
spatial
and
temporal
variability
in
the
types
of
treatment
applied
to
drinking
water.

4
EPA s
preliminary
review
of
the
literature
indicates
that
conventional
treatment
(
such
as
coagulation/
flocculation,
sedimentation,
and
filtration)
has
little
or
no
effect
on
the
removal
of
mobile
(
hydrophilic
or
lipophobic)
pesticides.
Disinfection
and
softening
can
facilitate
alteration
in
the
chemical
structure
of
the
pesticide,
or
transformation.
The
type
of
disinfectant
used
and
the
length
of
contact
time
between
the
water
and
disinfectant
are
factors
which
affect
the
impact
on
pesticide
transformation.
There
is
little
information
on
the
chemical
identity
of
transformation
products
formed
as
the
result
of
disinfection.
However,
disinfection
can
produce
toxic
by­
products
of
some
pesticides
(
eg.,
oxons
from
organophospates).
The
impact
of
softening
on
pesticide
transformation
is
dependent
on
the
potential
for
alkaline­
catalyzed
hydrolysis
of
the
pesticide.

The
Federal
Insecticide,
Fungicide,
and
Rodenticide
Act
Science
Advisory
Panel
(
SAP)
evaluated
the
literature
review
and
concurred
with
the
conclusions
(
www.
epa.
gov/
scipoly/
sap/
2000/
index.
htm#
september)
.
The
SAP
stated
that
immobile
(
hydrophobic/
lipophilic)
pesticides
may
be
removed
by
conventional
water
treatment
processes.

Proposed
Policy
OPP
is
announcing
and
seeking
public
comment
on
a
policy
to
provide
a
systematic
approach
for
considering
drinking
water
treatment
effects
on
pesticide
removal
and
transformation
in
FQPA
risk
assessments.
Because
most
surface
source
drinking
water
receives
some
form
of
water
treatment
prior
to
human
consumption,
the
proposed
treatment
policy
is
generally
applicable
to
surface
source
drinking
water.
A
similar
assumption
cannot
be
made
for
drinking
water
systems
using
ground
water
because
of
the
importance
of
private
wells
in
rural
areas.
Private
wells
are
not
generally
linked
to
water
treatment
systems
prior
to
human
consumption.
This
policy
is
based
on
scientific
conclusions
reached
as
a
result
of
OPP s
literature
review
and
on
our
assessment
of
the
availability
of
information
for
specific
pesticides
on
water
treatment
effects:

!
The
Environmental
Fate
and
Effects
Division
(
EFED)
will
provide
available
information
on
the
potential
and
measured
effects
from
drinking
water
treatment
(
e.
g.,
flocculation,
coagulation,
sedimentation,
filtration,
chlorination,
softening,
GAC/
PAC
treatment)
to
the
OPP s
Health
Effects
Division
(
HED)
Metabolism
Assessment
Review
Committee
(
MARC).
The
MARC
will
evaluate
this
information
and
determine
which,
if
any,
transformation
and
degradation
products
might
be
of
toxicological
concern.
This
information
will
also
be
considered
in
FQPA
Safety
Factor
decisions.

!
OPP
will
not
generally
conclude
that
treatment
mitigates
exposure
for
a
specific
pesticide
without
supporting
evidence.
Therefore,
if
sufficient
pesticide­
specific
information
is
not
available
on
effects
of
a
water
treatment
processes,
or
if
sufficient
information
is
not
available
on
the
extent
to
which
specific
processes
are
employed
within
the
pesticide
use
area,
FQPA
drinking
water
assessments
will
be
conducted
using
pesticide
concentrations
in
raw
or
ambient
waters
to
represent
pesticide
concentrations
in
finished
drinking
water.
This
policy
is
based
on
the
fact
that
conventional
water
treatment
processes
5
(
coagulation/
flocculation,
sedimentation,
and
filtration)
are
not
expected
to
remove
mobile
pesticides
during
treatment.

!
If
sufficient
pesticide­
specific
information
is
available
on
effects
of
a
water
treatment
process,
as
well
as
information
on
the
extent
to
which
such
process
is
employed
within
the
pesticide
use
area,
EFED
will
attempt
to
describe
quantitatively
the
potential
effects
of
drinking
water
treatment
for
that
pesticide
in
the
drinking
water
assessment.
This
description
will
include
effects
of
degradation
and
formation
of
transformation
products.

!
Monitoring
data
on
finished
drinking
water
may
also
represent
in
aggregate
the
effects
of
treatment
in
the
study
area.
However,
because
of
the
inherent
variability
associated
with
water
treatment
processes,
with
source
water
quality,
and
the
limited
availability
of
monitoring
data
on
pesticides
in
finished
drinking
water,
extrapolating
such
results
to
areas
outside
of
the
area
monitored
would
be
considered
on
a
case­
by­
case
basis.
It
is
anticipated
that
quantitation
of
drinking
water
treatment
effects
will
be
limited
to
pesticides
with
extensive
monitoring
data
on
finished
water
(
e.
g.
atrazine)
or
pesticides
with
monitoring
data
on
finished
water
from
limited
use
areas
(
e.
g.,
molinate).
Extrapolating
treatment
effects
across
compounds
with
similar
structures
will
be
considered
on
a
case­
by­
case
basis.

1.0
Introduction
The
Food
Quality
Protection
Act
of
1996
(
FQPA)
amended
the
Federal
Food,
Drug,
and
Cosmetic
Act
to
require
that
all
tolerances
(
maximum
legal
residues)
for
pesticide
residues
in
or
on
food
be
 
safe. 
The
term
 
safe 
means
that
EPA
has
determined
there
is
 
a
reasonable
certainty
of
no
harm 
from
aggregate
exposure
to
the
pesticide
residue,
including
anticipated
dietary
exposure
and
all
other
exposures
for
which
there
is
reliable
information.
Drinking
water
is
considered
a
pathway
of
potential
dietary
exposure
to
pesticides.
OPP
uses
a
variety
of
data,
methods,
and
approaches
to
assess
drinking
water
exposure
for
risk
assessments
completed
under
FQPA.

Generally,
available
monitoring
data
on
pesticides
in
drinking
water
are
limited
to
concentrations
measured
in
raw
or
untreated
water.
OPP
recognizes,
however,
that
a
large
percentage
of
the
population
drinks
water
that
has
undergone
some
form
of
treatment,
and
where
appropriate
data
permit,
OPP
intends
to
consider
the
impact
of
drinking
water
treatment
on
potential
human
exposure.
The
objectives
of
this
paper
are
to:
1)
present
a
preliminary
and
general
assessment
of
the
impact
of
different
treatment
processes
on
pesticide
removal
and
transformation
in
treated
drinking
water
derived
from
ground
and
surface
water
sources;
and
2)
describe
how
OPP
will
consider
the
impacts
of
drinking
water
treatment
in
characterizing
its
drinking
water
exposure
assessments
under
FQPA.

6
2.0
Science
Policy
and
Procedure
for
Incorporating
Water
Treatment
into
FQPA
Drinking
Water
Assessments
2.1
Policy
Development
Process.

OPP
originally
developed
a
background
document
on
this
topic
in
February,
2000,
and
solicited
comment
from
a
variety
of
internal
and
external
peer
reviewers.
All
external
peer
review
comments
addressed
technical
issues.
With
the
exception
of
one
reviewer,
written
comments
indicated
no
disagreement
with
the
technical
conclusions
regarding
removal
efficiencies
of
various
treatment
technologies
discussed
in
the
document.
The
technical
peer
review
comments
were
addressed
in
a
revised
version
of
the
literature
review.

The
background
document
was
submitted
to
the
FIFRA
Scientific
Advisory
Panel
(
SAP),
a
federal
advisory
committee
comprised
of
external,
independent
expert
scientists,
for
technical
review.
A
SAP
meeting
was
held
on
September
29,
2000
to
address
drinking
water
treatment
effects
on
pesticide
residues
in
water.
The
report
of
the
SAP
committee
on
this
topic
was
issued
on
February
12,
2001.
The
SAP
members
generally
concurred
with
the
technical
conclusions
of
the
document
(
www.
epa.
gov/
scipoly/
sap/
2000/
index.
htm#
september
).
The
primary
conclusion
of
the
SAP
report
was
that
conventional
treatment
(
coagulation/
flocculation,
sedimentation
and
filtration),
in
general,
is
not
effective
in
removing
residues
of
mobile
(
hydrophilic/
lipophobic)
pesticides
from
raw
surface
or
ground
water.
A
summary
of
the
SAP
comments
are
as
follows:

 
Hydrophobic
or
lipophilic
pesticides
may
be
removed
through
conventional
water
treatment
processes
such
as
coagulation/
flocculation,
sedimentation,
and
filtration.
 
Predicting
the
impact
of
a
water
treatment
process
on
pesticide
removal
and
transformation
is
hampered
by
variability
of
water
treatment
processes
employed
among
public
water
systems
and
the
variability
in
source
water
quality.
 
Bench
scale
or
 
jar 
tests
can
be
used
to
assess
the
impacts
of
water
treatment
processes
(
e.
g.,
coagulation,
flocculation
and
sedimentation,
and
adsorption
on
powdered
activated
carbon
(
PAC).
Because
jar
tests
are
expected
to
yield
higher
removal
efficiencies
than
actual
water
treatment
plants,
pilot
and
full
scale
water
treatment
plant
studies
are
needed
to
validate
water
treatment
effects.
 
Pesticides
that
exhibit
alkaline
hydrolysis
may
be
degraded
through
high
pH
water
softening
processes.
 
The
impact
of
disinfection
on
pesticide
transformation
should
be
considered
in
the
drinking
water
assessments.
An
evaluation
of
probable
disinfection
by­
products
should
be
evaluated
in
this
assessment
process.
 
The
Agency
should
assume
that
finished
water
pesticide
concentrations
are
the
same
as
the
raw
water
pesticide
concentrations
until
adequate
research
is
conducted
on
water
treatment
effects
on
pesticide
removal
and
transformation.
Exceptions
to
this
approach
may
occur
when
chlorination
or
hydrolysis
causes
chemical
transformation
of
the
pesticide.
It
is
important
to
consider
the
health
effects
of
the
transformation
products.
 
Monitoring
finished
drinking
water
levels
for
pesticides
found
in
raw
water
should
be
among
EPA s
highest
priorities
to
assess
water
treatment
effects
on
pesticide
removal
7
and
transformation.

2.2
Policy
for
Considering
Water
Treatment
in
FQPA
Drinking
Water
Assessments
The
proposed
policy
provides
a
systematic
approach
for
considering
drinking
water
treatment
effects
on
pesticide
removal
and
transformation
in
FQPA
risk
assessments.
Because
most
surface
source
drinking
water
receives
some
form
of
water
treatment
prior
to
human
consumption,
the
proposed
treatment
policy
is
generally
applicable
to
surface
source
drinking
water.
A
similar
assumption
cannot
be
made
for
drinking
water
systems
using
ground
water
because
of
the
importance
of
private
wells
in
rural
areas.
Private
wells
are
not
generally
linked
to
water
treatment
systems
prior
to
human
consumption.
This
policy
is
based
on
scientific
conclusions
reached
as
a
result
of
OPP s
literature
review
and
on
our
assessment
of
the
availability
of
information
for
specific
pesticides
on
water
treatment
effects:

!
OPP s
Environmental
Fate
and
Effects
Division
(
EFED)
will
provide
available
information
on
the
potential
and
measured
effects
from
drinking
water
treatment
(
e.
g.,
flocculation,
coagulation,
sedimentation,
filtration,
chlorination,
softening,
GAC/
PAC
treatment)
to
the
Health
Effects
Division
(
HED)
Metabolism
Assessment
Review
Committee
(
MARC).
The
MARC
will
evaluate
this
information
and
determine
which,
if
any,
transformation
and
degradation
products
might
be
of
toxicological
concern.
This
information
will
also
be
considered
in
FQPA
Safety
Factor
decisions.

!
OPP
will
not
generally
conclude
that
treatment
mitigates
exposure
for
a
specific
pesticide
without
supporting
evidence.
Therefore,
if
sufficient
pesticide­
specific
information
is
not
available
on
effects
of
a
water
treatment
processes,
or
if
sufficient
information
is
not
available
on
the
extent
to
which
specific
processes
are
employed
within
the
pesticide
use
area,
FQPA
drinking
water
assessments
will
be
conducted
using
pesticide
concentrations
in
raw
or
ambient
waters
to
represent
pesticide
concentrations
in
finished
drinking
water.
This
policy
is
based
on
the
fact
that
conventional
water
treatment
processes
(
coagulation/
flocculation,
sedimentation,
and
filtration)
are
not
expected
to
remove
mobile
pesticides
during
treatment.

!
If
sufficient
pesticide­
specific
information
is
available
on
effects
of
a
water
treatment
process,
as
well
as
information
on
the
extent
to
which
such
process
is
employed
within
the
pesticide
use
area,
EFED
will
attempt
to
describe
quantitatively
the
potential
effects
of
drinking
water
treatment
for
that
pesticide
in
the
drinking
water
assessment.
This
description
will
include
effects
of
degradation
and
formation
of
transformation
products.

!
Monitoring
data
on
finished
drinking
water
may
also
represent
in
aggregate
the
effects
of
treatment
in
the
study
area.
However,
because
of
the
inherent
variability
associated
with
water
treatment
processes,
with
source
water
quality,
and
the
limited
availability
of
monitoring
data
on
pesticides
in
finished
drinking
water,
extrapolating
such
results
to
areas
outside
of
the
area
monitored
would
be
considered
on
a
case­
by­
case
basis.
It
is
anticipated
that
quantitation
of
drinking
water
treatment
effects
will
be
limited
to
8
pesticides
with
extensive
monitoring
data
on
finished
water
(
e.
g.
atrazine)
or
pesticides
with
monitoring
data
on
finished
water
from
focused
or
limited
use
areas
(
e.
g.,
molinate).
Extrapolating
treatment
effects
across
compounds
with
similar
structures
will
be
considered
on
a
case­
by­
case
basis.

2.3
Evaluation
of
the
Water
Treatment
Data
OPP
will
evaluate
water
treatment
data
submitted
to
the
Agency
in
support
of
pesticide
registration
and
reregistration
activities.
Water
treatment
data
can
be
derived
from
studies
providing
information
on
the
removal/
transformation
efficiency
of
the
pesticide
and
identification
of
transformation
by­
products.
Because
there
are
no
standard
guideline
water
treatment
studies,
water
treatment
data
can
be
derived
from
a
simple
laboratory
study
(
commonly
referred
to
as
 
jar
test )
and
actual
water
treatment
plant
monitoring
studies.
(
Please
see
Section
3.6
for
more
details
on
water
treatment
assessment
techniques.)

The
proposed
policy
states
that
supporting
water
treatment
data
will
be
considered
in
drinking
water
assessments
when
sufficient
and
representative
pesticide­
specific
water
treatment
data
are
available.
Because
of
the
complexity
of
water
treatment
technology
associated
with
local
water
quality
conditions
across
pesticide
use
areas,
as
well
as
the
presence
of
unique
or
regionally
dependent
water
treatment
processes
or
sequences,
it s
difficult
to
establish
standard
criteria
for
defining
the
sufficiency
and
representative
nature
of
pesticide
specific
water
treatment
data.
Therefore,
OPP
will
consider
the
quality
of
water
treatment
data
on
a
case­
by­
case
basis.

Criteria
for
evaluation
of
water
treatment
data
are
expected
to
be
variable
because
of
the
various
types
of
water
treatment
data
as
well
as
the
variability
of
treatment
across
a
pesticide
use
area.
Based
on
recommendations
from
the
FIFRA
SAP,
general
evaluation
criteria
of
water
treatment
data
are
as
follows:

1.)
Laboratory
scale
treatment
studies
such
as
jar
tests
will
be
used
only
to
confirm
when
treatment
has
no
effect
on
pesticide
removal
and
transformation.
This
assessment
approach
was
recommended
by
the
SAP
because
jar
tests
are
known
to
exaggerate
the
removal
efficiency
when
compared
to
actual
treatment
plants.

2.)
When
jar
tests
show
pesticide
specific
removal
or
transformation,
pilot
plant
or
actual
water
treatment
plant
monitoring
studies
are
needed
to
establish
realistic
removal
or
transformation
efficiencies.
These
studies
should
represent
the
treatment
systems
and
processes
found
in
the
pesticide
use
area.
Submission
of
water
treatment
and
water
quality
data
in
the
pesticide
use
are
needed
to
ensure
the
representative
nature
(
bracketing
conditions
in
the
pesticide
use
area)
of
the
water
treatment
data.
Monitoring
data
should
provide
temporally­
paired
raw
water
and
finished
water
samples.
Also,
paired
samples
may
be
required
for
individual
treatment
processes
if
interactive
effects
are
expected
from
sequential
treatment
processes.

OPP
is
willing
to
work
with
the
scientific
community
(
including
pesticide
registrants)
to
9
design
scientifically
defensible
and
cost­
effective
protocols
for
a
particular
pesticide
that
could
generate
reliable
information
on
which
to
base
quantitative
estimates
of
treatment
effects.
Currently,
EFED
is
working
with
the
Office
of
Research
and
Development
(
ORD)
to
develop
water
treatment
protocols.
How
OPP
will
qualitatively
and/
or
quantitatively
factor
drinking
water
treatment
data
into
its
estimates
or
characterization
of
pesticide
concentrations
in
drinking
water
will
be
detailed
in
a
future
policy
paper.

10
3.0
LITERATURE
REVIEW
OF
THE
IMPACTS
OF
WATER
TREATMENT
ON
PESTICIDE
REMOVAL
AND
TRANSFORMATIONS
IN
DRINKING
WATER
3.1
Overview
3.1(
a)
Summary
of
the
Impact
of
Water
Treatment
on
Pesticide
Removal
and
Transformation
OPP
concludes
from
the
literature
review
that,
in
general,
the
conventional
water
treatment
at
most
Community
Water
Systems
(
CWSs),
specifically
coagulation­
flocculation,
sedimentation,
and
conventional
filtration,
does
not
remove
and
transform
pesticides
in
finished
drinking
water.
Disinfection
and
water
softening,
which
also
routinely
occur
at
CWSs
can,
however,
lead
to
pesticide
transformation
and,
in
some
cases,
pesticide
removal
or
degradation.
This
finding
is
important
because
disinfection
and
coventional
coagulation/
filtration
are
commonly
used
treatment
processes
at
CWSs
in
the
United
States.
Chemical
disinfection
has
been
shown
to
form
pesticide
degradation
products,
which
may
or
may
not
correspond
to
degradation
products
currently
considered
in
OPP
risk
assessments.
Particularly
for
those
pesticide
degradation
by­
products
which
are
not
observed
in
standard
metabolism
and
other
studies
required
by
OPP,
there
may
be
limited
information
on
the
nature
and
toxicological
importance
of
the
pesticide.
The
type
of
disinfectant
used
and
the
length
of
contact
time
with
the
disinfectant
are
important
factors
in
assessing
water
treatment
effects.

Powdered
activated
carbon
(
PAC)
filtration,
granulated
activated
carbon
(
GAC)
filtration,
and
reverse
osmosis
(
RO)
have
been
demonstrated
to
be
highly
effective
processes
at
removing
organic
chemicals,
including
certain
pesticides
(
primarily
acetanilide
herbicides),
but
specific
data
on
removal
of
most
pesticides
are
not
available.
Also,
air
stripping
is
only
effective
for
volatile
pesticides
or
those
with
a
high
Henry s
Law
Constant.
Among
these
organic
removal
treatment
processes,
PAC
is
the
more
common
method
because
it
can
be
used
in
concert
with
conventional
water
treatment
systems
with
no
significant
additional
capital
investment.
Available
data
suggest
that
about
46%
of
large
CWSs
(
serving
>
100,000
people)
use
PAC
at
some
time
during
the
year,
and
that
most
of
these
systems
are
surface
water­
based
systems
(
SAIC,
1999).
Air
stripping
is
an
effective
water
treatment
for
volatile
pesticides
(
Henry s
Law
Constants
>
1
X
10­
3
atm
m3
/
mole),
but
this
method
is
used
at
very
few
CWSs
(
less
than
1%
of
CWSs).

A
preliminary
correlation
analysis
of
the
environmental
fate
properties
of
pesticides
considered
in
this
paper
with
removal
efficiencies
does
not
indicate
any
trends
or
relationships,
making
it
difficult
to
predict
removal
efficiency
for
specific
compounds
without
additional
data.
However,
Speth
and
Miltner,
1998
reported
that,
in
general,
compounds
with
Freundlich
coefficients
on
activated
carbon
greater
than
200
ug/
g
(
L/
ug)
1/
n
would
be
amenable
to
removal
by
carbon
sorption.

11
3.2
Background
The
Food
Quality
Protection
Act
(
FQPA)
of
1996
requires
that
all
non­
occupational
routes
of
pesticide
exposure
be
considered
in
aggregate
and
cumulative
dietary
human
health
exposure
assessments
for
pesticide
tolerance
reassessment.
Because
drinking
water
is
a
route
of
potential
dietary
exposure,
it
is
factored
into
FQPA
dietary
exposure
assessments.
FQPA
drinking
water
exposure
assessments
are
based
on
screening
models
(
e.
g.
F
irst
I
ndex
R
eservoir
Scenario
Tier
(
FIRST),
GEN
eric
E
stimated
E
nvironmental
C
oncentration
(
GENEEC),
and
P
esti
cide
R
oot
Z
one
M
odel
(
PRZM)/
EXposure
A
nalysis
Modeling
S
ystem
(
EXAMS),
pesticide
occurrence
data
in
ambient
waters
[
e.
g.
,
NA
tional
W
ater
Q
uality
Assessment
(
NAWQA)],
and
appropriate
pesticide
occurrence
data
in
drinking
water
such
as
compl
iance
monitoring
data.
Generally,
neither
the
models
nor
modeling
data
support
the
estimation
of
pesticide
concentrations
in
 
treated 
drinking
water.
Treated
drinking
water
for
the
purpose
of
FQPA
exposure
assessment
will
be
defined
as
ambient
ground
or
surface
water
which
is
either
chemically
or
physically
altered
using
technology
prior
to
human
consumption.
As
a
potential
refinement
to
FQPA
drinking
water
exposure
assessments,
water
treatment
effects
(
including
both
pesticide
removal
as
well
as
transformation)
need
to
be
considered
and
appropriately
factored
into
the
aggregate
human
health
risk
assessment
process
under
FQPA.

Assessment
of
the
impacts
of
drinking
water
treatment
processes
on
the
level
of
pesticide
concentrations
in
ambient
water
and
the
resulting
levels
in
treated
water
requires
an
understanding
of
the
removal
efficiency
for
various
pesticides
and
treatment
processes,
as
well
as
an
understanding
of
the
spatial
and
temporal
distribution
of
treatment
systems
within
potential
pesticide
use
areas.
Assessment
of
treatment
processes
is
further
complicated
because
each
water
treatment
system
is
uniquely
designed
to
accommodate
local
water
quality
conditions
(
nature
and
levels
of
organic,
inorganic,
and
biological
contaminants),
the
number
of
persons
served,
and
economic
resources.

3.3
Technical
Approach
in
Assessing
Water
Treatment
Data
OPP
reviewed
Agency
documents,
including
research
articles
by
scientists
of
EPA/
Office
of
Research
and
Development
(
ORD)
and
EPA
publications,
basic
textbooks
on
water
treatment,
and
publications
in
the
open
literature
to
compile
information
on
the
removal
and
potential
transformation
of
pesticides
detected
in
raw
waters.
Information
obtained
through
personal
communication
was
also
considered.
This
information
was
then
summarized
in
tabular
form
to
highlight
the
removal
efficiencies
associated
with
different
treatment
processes
and
different
methods
used
to
estimate
these
efficiencies.
These
methods
include
bench
scale
studies
(
jar
tests),
pilot
plant
studies,
and
full­
scale
treatment
operations
that
used
distilled
water,
surface
water,
and
groundwater,
as
raw
water.
The
pesticide
removal
efficiencies
were
derived
from
studies
and
investigations
in
which
the
levels
of
pesticides,
before
and
after
treatment,
were
quantitatively
analyzed.
The
majority
of
these
treatment
operations
were
not
designed
specifically
to
remove
the
pesticides.

12
When
available,
data
on
the
chemical
transformation
of
pesticides
in
certain
treatment
operations
were
presented.
Pesticide
transformation
products
would
not
be
typically
expected
from
treatment
processes
involving
phase
separations
such
as
flocculation
and
sedimentation.
However,
chemical
transformation
of
pesticides
is
expected
from
chemical
or
biochemical
reactions
resulting
from
addition
of
acidic
or
basic
compounds,
biochemically
mediated
transformations,
and
treatment
chemicals
that
alter
the
redox
potential
of
the
systems
under
consideration.

3.4
Regulatory
History
Drinking
water
from
community
water
systems
(
CWSs)
and
non­
community
water
systems
(
NCWSs)
is
regulated
under
in
the
Safe
Drinking
Water
Act
(
SDWA).
Based
on
this
law,
maximum
contaminant
levels
(
MCLs)
have
been
established
by
EPA
for
83
contaminants,
including
24
pesticides,
some
of
which
are
no
longer
approved
for
use.
The
MCL
for
each
contaminant
is
based
on
a
consideration
of
the
best
available
technology
(
BAT)
as
well
as
occurrence
and
human
exposure,
health
effects
and
toxicity,
analytical
methods,
and
economics.
The
MCL
is
established
to
be
as
close
to
the
maximum
contaminant
level
goal
(
MCLG)
as
feasible.
The
MCL
for
each
contaminant
is
based
on
consideration
of
the
best
available
technology
(
BAT),
as
well
as
health
effects
and
toxicity,
occurrence
and
human
exposure,
analytical
methods,
and
economics.
There
are
14
currently
registered
pesticides
with
MCLs.

The
SDWA
requires
disinfection
of
all
public
water
supplies
and
establishes
criteria
of
filtration
requirements
for
public
water
supplies
derived
from
surface
water.
Additionally,
the
Surface
Water
Treatment
Rule
of
1989
(
SWTR)
requires
all
public
water
systems
using
surface
water
or
groundwater
under
the
influence
of
surface
water
to
disinfect
drinking
water.
Systems
may
be
required
to
filter
their
water
if
certain
water
quality
criteria
(
e.
g.,
turbidity,
removal
of
Giardia
cysts
and
viruses,
compliance
with
total
trihalomethane
MCL)
and
site­
specific
objectives
(
watershed
control
program)
are
not
met.
In
1991,
the
criteria
of
SWTR
were
amended
to
include
removal
of
Cryptosporidium.
These
regulations
serve
to
establish
the
baseline
treatment
processes
for
public
water
systems.

The
1996
amendments
to
the
SDWA
were
designed
to
focus
on
small
system
treatment
technologies
(
US
EPA,
1998).
The
amendments
were
designed
to:
1)
identify
technologies
that
small
systems
can
use
to
comply
with
the
Surface
Water
Treatment
Rule
(
SWTR)
and
National
Primary
Drinking
Water
Regulations
(
NPDWR);
2)
identify
best
available
technologies
(
BATs)
for
larger
systems;
and
3)
evaluate
emerging
technologies
as
potential
compliance
or
variance
technologies
for
both
existing
and
future
regulations.
Small
treatment
systems,
as
defined
in
the
1996
amendment
of
SDWA,
serve
populations
of
10,000
or
fewer
people.

Granular
activiated
carbon
(
GAC)
under
the
SDWA
is
the
best
available
technology
(
BAT)
for
removing
synthetic
organic
chemicals
(
SOC);
virtually
all
pesticides
are
SOCs.
Other
recommended
BATs
are
aeration
technologies
for
removal
of
dibromochloropropane
and
chlorination
or
ozonation
for
removal
of
glyphosate.

13
The
Disinfectants/
Disinfection
By­
Products
Rule
(
D/
DBP)
was
finialized
in
1998.
The
rule
deals
with
the
halogenated
compounds
generated
during
disinfection
or
chlorination
of
raw
waters
with
dissolved
organic
matter
(
humic
acids,
fulvic
acids,
etc.).
Maximum
residual
disinfectant
limits
(
MRDLs)
have
been
set
and
allowable
levels
of
disinfection
by­
products
such
as
trihalomethanes,
haloacetic
acids,
haloketones,
haloacetonitriles,
etc.)
were
established.`
In
a
similar
fashion,
the
European
Union
(
EU)
has
issued
the
drinking
water
directive
of
1998
that
sets
a
maximum
concentration
of
0.0001
mg/
L
for
individual
pesticides
or
degradation
products
and
0.0005
mg/
L
for
total
pesticide
residues
in
drinking
water
after
treatment
(
Acero
et
al,
2000,
http://
europa.
eu.
int/
water/
water­
drink/
98_
83en.
pdf
).

3.4(
a)
Pesticides
Currently
Regulated
Under
the
SDWA
Under
the
current
SDWA,
allowable
levels
of
some
pesticides
should
not
exceed
their
MCLs.
These
MCLs
are
established
to
be
protective
of
human
health
and
must
be
 
feasible. 
Feasibility
is
determined
by
BAT
removal
efficiency,
levels
of
contaminants
in
raw
water,
water
quality
parameters,
and
the
contaminant
concentrations
that
can
be
accurately
quantified
analytically.
The
MCLs
of
the
14
currently
registered
pesticides
are:

Pesticide
MCL
(
µ
g/
L)
Atrazine
Alachlor
Aldicarb
Carbofuran
2,4­
D
Diquat
Endothall
Glyphosate
Lindane
Methoxychlor
Oxamyl
Pentachlorophenol
Picloram
Simazine
3.5
Water
System
Statistics
3
2
3
40
70
20
100
700
0.2
40
200
1
500
4
Under
the
SDWA,
a
public
water
system
(
PWS)
is
any
system
which
provides
water
for
human
consumption
through
water
pipes
or
has
at
least
15
service
connections
or
regularly
serves
an
average
of
at
least
25
people
individuals
daily
for
60
days
in
the
year.
A
PWS
is
either
a
community
water
system
(
CWS)
or
non­
community
water
system
(
NCWS).
Non­
transient
non­
community
water
systems
are
defined
as
water
systems
that
serve
less
than
25
of
the
same
people
for
at
least
six
month
period.
An
example
of
non­
transient
community
water
system
is
a
well
serving
a
school
or
hospital.
Transient
non­
community
water
systems
are
water
systems
that
do
not
regularly
serve
at
least
25
of
the
same
people
over
a
six
month
period.
An
example
of
a
non­

14
transient
non­
community
water
system
is
a
well
serving
a
campground
or
roadside
rest
area.

Approximately
23
million
people
in
the
United
States
obtain
their
drinking
water
from
sources
other
than
public
water
systems.
The
remaining
252
million
people
in
the
United
States
obtain
their
drinking
water
from
Community
Water
Systems
(
CWSs),
with
84
million
people
relying
on
solely
groundwater­
based
systems
and
about
168
million
people
relying
on
surface
water
in
part
or
in
whole
(
Personal
Communication
with
Chuck
Job
USEPA/
OW,
2000).
In
general,
CWSs
are
regulated
under
the
Safe
Drinking
Water
Act
(
SDWA)
and
are
required
to
meet
certain
standards.
This
means
that
these
systems
generally
use
some
form
of
water
treatment,
particularly
of
surface
water,
prior
to
distribution
into
homes
and
businesses.

Typically,
the
sophistication
of
the
water
treatment
technology
is
dependent
on
the
population
served,
type
of
source
water,
and
physico­
chemical
properties
of
the
source
water
(
USEPA,
1997).
These
factors
are
discussed
in
the
following
sections.

3.5(
a)
Population
Served
(
Size
of
Water
Treatment
Facilities)

The
size
of
Community
Water
Systems
(
CWSs)
is
expected
to
be
dependent
on
the
water
demand
or
population
served.
Based
on
the
1995
CWS
survey
(
USEPA,
1997),
85%
of
CWSs
are
small
systems
serving
3,300
or
fewer
people.
Medium
(
serving
3,301
to
50,000
people)
and
large
(
serving
>
50,000
people)
CWSs
account
for
only
13%
and
2%
of
CWS
systems,
respectively.
Although
these
medium
and
large
systems
represent
only
15%
of
number
of
CWS,
they
are
responsible
for
serving
approximately
90%
population.

3.5(
b)
Types
of
Water
Treatment
Associated
with
Different
Source
Waters
The
percentage
of
CWSs
using
no
water
treatment
technologies
has
decreased
between
1976
to
1995
(
EPA
815­
R­
001a).
CWSs
using
no
water
treatment
typically
are
small
CWSs
(
serving
<
500
people)
using
surface
water
or
small
to
medium
size
CWSs
using
ground
water
(
US
EPA,
1999).
Although
there
are
larger
CWSs
(
serving
501
to
100,000
people)
using
groundwater
with
no
water
treatment,
they
represent
a
relatively
small
percentage
(
0.9
to
16%
of
systems)
of
the
CWS
systems.
With
the
exception
of
the
small
CWSs
(
serving
<
500
people)
using
surface
water,
all
CWSs
withdrawing
from
surface
water
are
using
some
type
of
water
treatment.
This
trend
can
be
attributed
to
EPA s
promulgation
of
the
Surface
Water
Treatment
Rule
of
1989.

The
1995
Community
Water
System
Survey
identified
approximately
38
different
water
processes
for
water
systems
using
mixed
source
waters.
Water
treatment
is
mainly
established
for
the
following
purposes:
disinfection,
sediment
removal,
organic
removal,
and
corrosion
control.
Disinfection
is
the
most
common
treatment
process
for
CWSs
using
only
groundwater
(
Table
3.1).
The
predominant
treatment
processes
for
CWSs
using
surface
water
are
disinfection/
oxidation,
flocculation/
coagulation,
and
conventional
(
sand
or
gravel)
filtration
(
Table
3.2).
Water
systems
using
a
mixture
of
ground
and
surface
waters
generally
use
similar
treatment
technologies
as
are
used
for
the
predominant
source
water
type
(
USEPA,
1997).

15
Control
of
turbidity
is
the
main
difference
in
treatment
strategies
for
CWS
using
surface
water
or
surface
water/
ground
water.

Table
3.1.
Percent
of
Ground
Water
Systems
with
Treatment1
Treatment
Category
Population
Category
(
Number
of
People
Served)

Less
than
100
101­
500
501­
1,000
1,001­
3,000
3,301­
10,000
10,001­
50,000
50,001
­
100,000
More
than
100,000
Disinfection
52.8
77.9
84.0
79.7
86.8
96.5
86.3
96.4
Aeration
1.5
6.3
17.1
19.9
29.7
33.0
49.1
44.1
Oxidation
3.2
6.6
9.4
4.2
10.9
9.3
18.6
5.4
Ion
Exchange
0.7
1.6
3.8
1.9
4.6
3.3
1.2
0
Reverse
Osmosis
0
1.2
0
0.9
1.2
0.7
1.2
0
GAC
0
0.5
0
0.4
0
6.7
7.5
9.0
PAC
0
0
0
0
0.2
0.3
0
1.8
Filtration
11.8
8.0
15.9
14.9
29.5
29.6
50.3
51.4
Coagulation/
Flocculation
1.5
5.4
4.2
3.4
8.1
15.1
24.2
25.2
Lime/
Soda
Ash
Softening
2.1
3.7
4.1
5.2
7.0
12.2
17.4
32.4
Recarbonation
0
0.5
0
1.1
3.0
6.1
7.5
10.8
1­
Data
taken
from
SAIC,
1999.

Table
3.2.
Percent
of
Surface
Water
Systems
with
Treatment1
Treatment
Category
Population
Category
(
Number
of
People
Served)

Less
than
100
101­
500
501­
1,000
1,001­
3,000
3,301­
10,000
10,001­
50,000
50,001
­
100,000
More
than
100,000
Disinfection
92.8
94.1
100
100
96.0
98.0
100
100
Aeration
0
0
1.4
5.5
8.5
3.5
10.3
14.3
Oxidation
0
2.0
7.2
5.8
7.7
10.5
5.7
4.6
Ion
Exchange
0
0
0
0
0
0
0
0
Reverse
Osmosis
0
0
0
0
0
0
0
0
GAC
3.9
4.3
1.4
2.3
4.7
10.2
14.9
11.2
PAC
0
2.0
3.0
4.6
18.6
24.6
34.2
45.9
Filtration
78.5
71.2
79.3
81.7
86.5
96.3
88.0
93.4
Coagulation/
Flocculation
27.5
52.6
70.2
78.5
95.4
94.5
93.7
99.5
16
Table
3.2.
Percent
of
Surface
Water
Systems
with
Treatment1
Treatment
Category
Population
Category
(
Number
of
People
Served)

Less
than
100
101­
500
501­
1,000
1,001­
3,000
3,301­
10,000
10,001­
50,000
50,001
­
100,000
More
than
100,000
Lime/
Soda
Ash
Softening
3.9
8.1
20.5
17.5
10.8
6.9
5.7
5.1
Recarbonation
0
0
0
0
0
0
1.1
5.1
1­
Data
are
taken
from
SAIC,
1999.

Water
treatment
in
PWSs
consists
of
a
sequence
of
individual
treatment
processes.
Conventional
treatment,
defined
as
a
sequence
of
processes
typically
used
in
water
treatment,
may
include
the
following
treatment
processes:
clarification
(
sedimentation),
filtration,
softening,
recarbonation,
and
chlorination
(
Miltner,
et
al.
1989).
The
selection
of
treatment
processes
to
be
used
at
a
given
PWS,
however,
is
dependent
on
several
factors
including,
seasonal
changes/
requirements,
water
quality,
watershed
properties,
population
served,
and
economics.
Therefore,
water
treatment
processes
at
each
PWS
consist
of
a
unique
set
of
processes
which
cannot
be
generalized
or
exactly
replicated.
Disinfection/
oxidation
processes,
for
example,
can
vary
with
regard
to
the
selection
of
disinfectant,
location
of
disinfection
process
in
water
treatment
process,
and
may
depend
on
the
microorganisms
present
in
the
source
water,
turbidity
of
source
water,
and
the
nature
and
presence
of
organic
and
inorganic
contaminants.
Modification
of
any
variable
in
the
disinfection
process
can
drastically
alter
the
efficiency
of
the
process,
as
well
as
the
production
of
byproducts
in
finished
water.
The
chemical
and
physical
engineering
of
sequential
water
treatment
processes
needs
to
be
considered
in
assessing
pesticide
removal
and
transformation.

3.6
Water
Treatment
Assessment
Techniques
Basic
water
treatment
assessment
approaches
fall
into
three
categories:
relational
(
regression
modeling),
experimental
(
prototype
studies),
and
actual
field
monitoring.
The
relational
or
correlative
approach
relies
on
regressing
pesticide
removal
for
a
specific
process
to
environmental
fate
properties
of
pesticides.
The
pesticides
whose
removal
rates
have
been
reported
in
the
literature
do
not
have
sufficiently
variable
properties
to
develop
regression
equations
that
apply
to
a
wide
range
of
chemicals.
Therefore,
OPP s
preliminary
analysis
could
not
establish
any
clear
relationship
or
trend
between
the
ability
of
a
specific
water
treatment
process
to
reduce
the
concentration
of
a
pesticide
in
water
and
the
environmental
fate
and
characteristics
of
the
pesticide.
(
Please
see
Section
3.9).

Prototype
studies
are
the
standard
approach
to
assess
and
optimize
water
treatment
processes
(
J.
M.
M.
Consulting
Engineers,
1985
and
USEPA,
1989).
The
most
common
approach
is
the
bench
scale
laboratory
study
commonly
referred
to
a
 
jar 
study.
A
jar
study
is
a
static
mixed
reactor
system
(
mixed
water
in
a
jar).
Although
there
is
no
standard
test
protocol
for
jar
studies,
a
standard
protocol
has
been
proposed
by
Lytle,
1995.
The
test
study
is
recommended
to
assess
the
impact
of
primary
water
treatment
processes
including
coagulation,
flocculation,
and
sedimentation
(
J.
M.
M.
Consulting
Engineers,
1985).
Jar
tests
are
also
recommended
to
assess
17
turbidity
removal;
appropriate
dose
of
coagulants;
impact
of
polymeric
aids;
impact
of
mixing
time;
and
control
measures
for
iron
and
manganese
precipitation
(
J.
M.
M.
Consulting
Engineers,
1985).
Advantages
of
jar
studies
are
the
relative
ease
and
costs
associated
with
the
method.
Disadvantages
of
jar
tests
as
a
method
for
determining
impacts
of
conventional
drinking
water
treatment
on
the
levels
of
pesticides
in
finished
water
are
that
they
typically
do
not
permit
evaluation
of
how
characteristics
of
the
raw
source
water
(
e.
g.,
turbidity
or
pesticide
concentration)
by
which
vary
both
temporally
and
spatially­­
may
affect
the
ability
of
the
water
treatment
process
to
reduce
pesticide
concentrations
(
Carrol,
1985
and
Lytle,
1995).
Another
disadvantage
of
jar
studies
is
that
they
do
not
evaluate
the
combination
of
treatment
processes
operating
at
a
plant
scale.

More
refined
prototype
studies
are
pilot
scale
and
plant
scale
studies.
These
types
of
studies
are
recommended
to
assess
filtration
processes
(
J.
M.
M.
Consulting
Engineers,
1985).
Filtration
variables
evaluated
using
pilot
scale
studies
are:
filter
media
size,
bed
depth,
filter
media
type,
filtration
rates,
filter
washing
conditions.
Other
specialized
studies
can
be
conducted
to
assess
specific
treatment
issues
including
volatile
organic
carbon
(
VOC)
removal
using
packed
towers,
air
loading
rates
in
air
stripping,
disinfectant
dose
and
type,
or
evaluation
of
adsorption
from
GAC.
The
actual
scale
of
the
special
studies
should
be
commensurate
with
simulation
of
full
scale
water
treatment
processes
(
J.
M.
M.
Consulting
Engineers,
1985).

Actual
monitoring
at
water
treatment
plants
is
conducted
for
regulatory
and
research
purposes.
The
general
approach
of
the
monitoring
studies
is
to
analyze
raw
source
water
at
the
water
system
intake
and
finished
drinking
water.
The
major
advantage
of
this
approach
is
that
the
whole
water
treatment
process
is
evaluated
rather
than
an
individual
process.
A
disadvantage
of
water
plant
monitoring
is
the
difficulty
in
conducting
precise
temporally­
paired
raw
and
finished
water
sampling.
This
type
of
sampling
is
required
to
estimate
removal
or
transformation
efficiencies.
Also,
an
assessment
on
the
impact
of
individual
treatment
processes
within
the
water
plant
requires
paired
sampling
before
and
after
each
treatment.

3.7
Water
Treatment
Processes
and
Removal
Efficiencies
3.7(
a)
Conventional
Treatment
A
typical
system
for
surface
water
treatment
generally
consists
of
pre­
settling,
coagulation/
flocculation
(
sediment
removal),
granular
filtration
(
sediment
removal),
corrosion
control
(
pH
adjustment
or
addition
of
corrosion
inhibitors),
and
disinfection
(
J.
M.
M.
Consulting
Engineers,
1985;
Faust
and
Aly,
1999;
USEPA,
1989).
It
is
important
to
note
there
are
many
variations
on
this
common
sequence,
regarding
points
of
addition
of
a
wide
variety
of
chemicals
(
e.
g.,
chlorine,
ammonia,
ozone,
coagulants,
filter
aids,
PAC,
etc.).
The
pre­
settling
process
is
a
preliminary
removal
of
materials
(
including
non­
colloidal
sediment)
from
the
raw
water.
The
water
is
then
treated
with
alum
and
polymers
to
encourage
flocculation
of
the
colloidal
materials
(
including
suspended
sediment)
and
then
allowed
to
settle.
Next,
the
water
is
passed
through
a
granular
filter
comprised
of
sand
and
possibly
anthracite.
After
filtering,
the
water
is
conditioned
to
prevent
corrosion
and
then
disinfected
using
either
chlorine
or
chloramines.

18
A
modification
to
the
typical
treatment
process
is
the
use
of
granular
activated
carbon
(
GAC)
or
powder
activated
carbon
(
PAC)
for
the
control
of
odors
and
taste
in
the
finished
water.
This
modification
is
applied
through
the
filtration
process
either
through
the
formation
of
a
filtration
bed
using
GAC
or
through
the
addition
of
PAC
prior
to
coagulation/
flocculation
and
filtration.

3.7(
a)
1
Coagulation/
Flocculation
Coagulation
and
flocculation
is
a
two­
step
process
to
remove
inorganic
and
organic
colloidal
materials
from
water
(
J.
M.
M.
Consulting
Engineers,
1985).
Colloidal
materials
are
particles
that
are
so
small
(
less
than
10
µ
m)
that
they
stay
suspended
in
the
water.
They
often
have
charged
surfaces
that
cause
them
to
repel
each
other.
The
coagulation
process
neutralizes
the
colloid s
surface
charge,
which
is
then
followed
by
mixing,
and
eventually
causes
flocculation
(
the
joining
of
individual
particles)
of
the
colloids
into
aggregates
called
 
flocs .
The
flocs
are
then
large
enough
to
settle
from
the
water
column.
This
process
is
needed
to
remove
turbidity
(
inorganic
colloids)
and
color
(
organic
colloids).
Removal
of
organic
colloids
such
as
humic
and
fulvic
acids
is
critical
because
they
are
known
precursors
to
the
formation
of
disinfection
by­
products
(
e.
g.,
trihalomethanes)
when
chlorine
is
added.

Commonly
used
coagulants
are
inorganic
salts
[
alum
(
Al2
(
SO4
)
3
)
,
aluminum
chloride
(
AlCl3
),
ferric
sulfate
(
Fe2
(
SO4
)
3
)
,
ferric
chloride
(
FeCl3
)
].
Certain
organic
polymers
are
also
used.
Inorganic
salts
are
effective
coagulants
because
Al+
3
and
Fe+
3
hydrolyze
to
form
positively
charged
hydrolysis
species
for
neutralization
of
the
surface
charge
for
colloid
destabilization.
Additionally,
these
ions
hydrolyze
to
form
amorphous
hydroxides,
Al(
OH)
3
and
Fe(
OH)
3
,
which
cause
physical
aggregation
through
colloid
entrapment.
The
time
required
for
coagulation/
flocculation
to
occur
is
a
critical
factor.
Typically,
coagulation
and
sweep
floc
formation
is
rapid
(
0.5
to
30
seconds).
Water
is
typically
held
in
a
flocculation
basin
for
15
to
45
minutes
(
USEPA,
1989).
The
optimum
pH
range
for
coagulation
is
about
6.5
(
J.
M.
M.
Consulting
Engineers,
1985
and
USEPA,
1989).
Higher
pH,
above
pH
8,
will
result
in
dissolution
of
the
Al(
OH)
3
flocs.
Recommended
alum
dose
rates
range
from
5
to
150
mg/
L
(
USEPA,
1989).
Natural
and
synthetic
polymers
are
also
used
to
form
different
charges
(
cationic
and
anionic
)
for
neutralization
of
various
surface
charges.
Cationic
polymers
(
positive
charge)
are
generally
used
as
primary
coagulants.
Typical
polymer
dosages
range
from
1.5
to
10
mg/
L
(
USEPA,
1989).
Nonionic
and
anionic
polymers
are
used
to
strengthen
flocs.
They
can
be
added
at
alum
at
polymer
ratios
ranging
from
100:
1
to
50:
1
(
USEPA,
1989).
Jar
tests
are
recommended
to
evaluate
coagulant
doses.

Organic
compounds
potentially
removed
through
coagulation/
flocculation
are
hydrophobic,
low
molecular
weight
acidic
functional
groups
(
e.
g.,
carbonyl
and
carboxyl
functional
groups),
or
high
molecular
weight
compounds
(
USEPA,
1989).
Coagulation
processes
have
been
developed
to
take
advantage
of
adsorption
on
surfaces
of
Al(
OH)
3
and
Fe(
OH)
3
flocs
(
USEPA,
1989).
EPA
recommendations
include:

Acidification
­
Add
acid
prior
to
coagulant
addition
to
encourage
cationic
species
19
formation
and
sorption
on
colloid
surfaces;

Flocculation
­
Addition
of
anionic
polymer
after
the
coagulant
addition;
and,

Adsorption
Process
­
Addition
of
powdered
activated
carbon
to,
or
with,
the
addition
of
coagulant
for
organic
removal.

Miltner
et
al.,
(
1989)
provide
information
on
the
possible
removal
of
pesticides
with
conventional
treatment.
In
this
study,
three
triazine
pesticides
(
atrazine,
simazine,
and
metribuzin),
two
acetanilides
(
alachlor
and
metolachlor),
linuron,
and
carbofuran
were
spiked
into
Ohio
River
water
in
jar
tests.
The
initial
concentrations
of
the
pesticides
(
Co
)
as
shown
in
Table
3.3,
range
from
34.3
to
93.4
µ
g/
L.
After
alum
coagulation
[
Al2
(
SO4
)
3
@
14H2
0:
15­
30
mg/
L],
the
initial
turbidity
of
the
raw
water
(
6
­
42
NTU,
Nephelometric
Turbidity
Units)
dropped
to
less
than
1
NTU
in
the
settled
water.
Table
3.3
summarizes
the
data
obtained
on
the
possible
removal
of
the
eight
pesticides
during
alum
coagulation.
No
removal
of
the
triazine
pesticides,
linuron,
and
carbofuran
was
observed.
The
removal
of
alachlor
and
metolachlor
was
low
and
ranged
from
4
to
11
%
percent.

Table
3.3.
Removal
of
Pesticides
by
Coagulation.

Pesticide
Coagulant
(
dose,
mg/
L)*
Initial
Concentration
(
µ
g/
L)
%
Removal
Atrazine
Alum
(
20)
65.7
(
SW)*
0
Simazine
Alum
(
20)
61.8
(
SW)
0
Metribuzin
Alum
(
30)
45.8
(
SW)
0
Alachlor
Alum
(
15)
43.6
(
SW)
4
Metolachlor
Alum
(
30)
34.3
(
SW)
11
Linuron
Alum
(
30)
51.8
(
SW)
0
Carbofuran
Alum
(
30)
93.2
(
SW)
0
From
Miltner
et
al.,
1989
*
SW
=
surface
water
3.7(
a)
2
Softening
Water
softening
is
used
to
lower
the
water
hardness,
which
is
represented
by
the
summation
of
calcium
(
Ca2+
)
and
magnesium
(
Mg2+
)
concentrations
in
water.
Hardness
reduces
the
effectiveness
of
soaps
and
detergents
and
hard
water
often
leaves
films
and
deposits
on
surfaces
in
contact
with
it.
The
recommended
hardness
of
drinking
water
can
range
from
50
to
150
mg/
L
(
J.
M.
M.
Consulting
Engineers,
1985).
Water
softening
can
be
achieved
through
precipitation
of
Ca+
2
and
Mg+
2
or
ion
exchange.
Precipitation
of
CaCO3
and
Mg(
OH)
2
requires
adjusting
the
pH
to
between
9.3
and
10.5.
Alteration
of
pH
may
be
accomplished
using
either
lime
or
caustic
soda
(
NaOH).
After
precipitation,
the
water
pH
is
lowered
using
recarbonation
20
(
dissolving
CO2
in
water).
Ion
exchange
using
cation
exchange
resins
is
another
technique
used
in
water
softening.

The
process
of
softening
or
softening­
clarification
was
evaluated
for
its
ability
to
remove
pesticides
from
water.
Data
collected
from
the
full­
scale
treatment
plants
indicated
that
atrazine,
cyanazine,
metribuzin,
alachlor
and
metolachlor
at
initial
concentrations
in
parts
per
billion
level
(
µ
g/
L)
were
not
removed
during
the
softening­
clarification
process.
In
contrast,
parent
carbofuran
was
reported
as
100%
removed.
During
softening
when
the
pH
of
the
solution
reached
between
10
to
11,
alkaline
hydrolysis
of
carbofuran
could
have
taken
place,
especially
if
there
was
sufficient
detention
or
contact
time.
However,
no
analysis
of
degradation
products
was
reported.
Based
on
environmental
fate
data
from
EPA/
OPP
(
USEPA,
1999)
and
Nanogen
Index
(
1975),
carbofuran
hydrolyzes
under
alkaline
conditions
to
form
carbofuran­
7­
phenol
and
3­
hydroxycarbofuran.

Table
3.4.
Removal
of
Pesticides
Associated
with
Softening­
Clarification
at
Full­
Scale
Treatment
Plants.

Pesticide
Initial
Concentration
(
µ
g/
L)
%
Removal
Atrazine
7.24
0
Cyanazine
2.00
0
Metribuzin
0.53
­
1.34
0
Simazine
0.34
0
Alachlor
3.62
0
Metolachlor
4.64
0
Carbofuran
0.13
­
0.79
100
From
Miltner
et
al.
(
1989)

3.7(
a)
3
Sedimentation
Sedimentation
is
effective
in
removing
materials
and
particulates
with
densities
greater
than
water
(
1
g/
cm3
)
(
J.
M.
M.
Consulting
Engineers,
1985),
which
settle
out
under
the
influence
of
gravity.
Sedimentation
in
the
water
treatment
process
occurs
following
flocculation
and
generally
precedes
filtration.
Additionally,
sedimentation
may
occur
in
retention
basins
before
water
enters
the
water
treatment
plant.
No
data
were
available
or
reviewed
to
assess
the
effectiveness
of
sedimentation
on
pesticide
removal
and
transformation.

3.7(
a)
4
Filtration
Filtration
is
considered
an
integral
step
in
the
water
treatment
process
for
particulate
removal,
including
microorganism
(
Giardia
lamblia),
algae,
colloidal
humic
compounds,
viruses,
asbestos
fibers,
and
suspended
clays
(
J.
M.
M.
Consulting
Engineers,
1985).
Conventional
filtration
has
been
defined
as
 
a
series
of
processes
including
coagulation,
flocculation,
sedimentation,
and
filtration
resulting
in
particulate
removal 
(
40
CFR
141.2).
For
this
paper,

21
filtration
will
be
defined
as
a
process
of
particulate
removal
through
interaction
with
filter
media
either
through
straining
or
non­
straining
mechanisms
(
J.
M.
M.
Consulting
Engineers,
1985).
Filters
can
be
made
using
screens
(
e.
g.,
polyethylene,
stainless
steel,
cloth),
diatomaceous
earth,
and
granular
materials
(
e.
g.,
sand,
anthracite
coal,
magnetite,
garnet
sand,
and
ground
coconut
shells).
These
filters
can
effectively
remove
particulate
materials
with
diameters
of
up
to
10
mm.
Coagulation­
flocculation
generally
precedes
sedimentation,
which
precedes
filtration.
This
sequence
of
treatment
is
common
in
conventional
water
treatment
processes.
Water
flow
through
filters
can
be
controlled
by
gravity
(
granular
filters)
or
under
pressure
(
diatomaceous
earth
filters).
Factors
impacting
filter
efficiency
are
related
to
the
particulate
size,
granular
size
distribution,
filtration
rate,
surface
properties
of
the
filter,
and
head
pressures
(
J.
M.
M.
Consulting
Engineers,
1985,
USEPA,
1989).
No
data
were
reviewed
to
assess
the
effectiveness
of
filtering
(
except
granular
activated
carbon)
on
pesticide
removal
and
transformation.
Other
filter
configurations
may
include
filter
adsorbers
(
capping
a
sand
filter
with
GAC)
or
post­
filter
adsorbers
(
separate
GAC
beds
after
sand
filtration).

3.7(
b)
Disinfection/
Chemical
Oxidation
Disinfection
is
the
process
for
inactivation
or
destruction
of
pathogens
(
including
bacteria,
amoebic
cysts,
algae,
spores,
and
viruses)
in
water
(
J.
M.
M.
Consulting
Engineers,
1985).
Disinfection
also
has
the
the
potential
to
remove
some
pesticides
through
oxidation.
Inactivation
or
destruction
of
pathogens
occurs
through
chemical
oxidation
of
cell
walls
or
other
mechanisms.
Chemical
disinfectants
listed
in
sequential
order
from
highest
to
lowest
oxidation
potential
are
ozone
(
O3
),
chlorine
dioxide(
ClO2
)
,
chlorine
(
Cl2
),
and
chloroamines
(
J.
M.
M.
Consulting
Engineers,
1985
and
USEPA,
1989).
Other
advanced
oxidation
processes
(
AOP)
are
ozone
(
O3
)
hydrogen
peroxide
(
H2
O2
),
Ultraviolet
(
UV)­
O3
,
O3
at
high
pH
(
pH
>
8),
or
potassium
permanganate
(
KMnO4
)
(
USEPA,
1989).
Physical
disinfection
process
utilizes
ultraviolet
radiation
(
UV),
which
encourages
photodegradation
of
nucleic
acids
in
microorganisms
(
USEPA,
1989).
This
process
is
conducted
at
wavelengths
ranging
250
to
270
nm
(
USEPA,
1989).

Primary
disinfection
occurs
prior
to
or
during
the
water
treatment
process.
Chlorine,
O3
,
and
ClO2
are
used
as
the
primary
disinfectants.
The
target
dose
rate
for
chlorination
is
to
achieve
a
maximum
free
chlorine
concentration
(
hypochlorous
acid
+
hypochlorite)
of
1
mg/
L
(
USEPA,
1989).
Secondary
disinfection
is
used
to
establish
residual
concentrations
of
disinfectants
in
drinking
water.
Monochloramine
and
chlorine
are
used
as
secondary
disinfectants.
Although
the
order
of
oxidation
potential
generally
describes
the
effectiveness
of
the
disinfectant
(
a
high
oxidation
potential
is
highly
effective),
the
kinetics
of
oxidation
can
alter
the
relative
effectiveness
of
disinfectants.
The
effectiveness
of
chemical
disinfection
also
is
dependent
on
water
quality
(
including
turbidity,
quantity
and
types
of
organics,
pH,
and
temperature),
contact
time,
and
application
time
in
the
water
treatment
process
(
J.
M.
M.
Consulting
Engineers,
1985
and
USEPA
1989).

Water
quality
is
an
important
factor
in
controlling
disinfectant
effectiveness
as
well
as
formation
of
byproducts.
The
pH
of
the
water
is
critical
in
controlling
the
distribution
of
the
active
chlorine
species
(
hypochlorous
acid)
and
hydroxy
radicals
from
ozone
(
J.
M.
M.
Consulting
Engineers,
1985
and
USEPA,
1989).
The
water
turbidity
is
critical
in
determining
the
22
disinfectant
dose
as
well
as
the
amounts
and
kinds
of
disinfection
by­
products.
Water
high
in
turbidity
requires
a
higher
disinfectant
concentration
because
of
disinfectant
demand
exerted
by
the
particulates.
Bench­
scale
studies
(
e.
g.,
jar
tests)
are
recommended
to
determine
the
disinfectant
dosage.

A
major
consideration
regarding
chemical
disinfection
is
the
formation
of
disinfection
by­
products.
Maximum
concentrations
of
disinfection
byproducts
are
expected
when
there
are
high
concentrations
of
organic
compounds
or
when
there
is
long
contact
time
with
the
disinfectant
(
J.
M.
M.
Consulting
Engineers,
1985
and
USEPA,
1989).
Water
treatment
processes
that
remove
natural
or
synthetic
organics
prior
to
disinfection
are
expected
to
minimize
disinfectant
by­
product
concentrations
in
drinking
water
due
to
removal
of
precursor
materials.
Halogenated
disinfection
by­
products
are
expected
from
chlorine
and
chlorine
dioxide
(
USEPA,
1989).
Chloroamines
are
not
expected
to
form
comparable
quantities
of
disinfection
by­
products
when
compared
to
chlorine.
Ozone
is
recommended
as
an
alternative
disinfectant
to
reduce
the
concentrations
of
disinfectant
by­
products
(
AWWA
Water
Quality
and
Treatment
Handbook).

In
laboratory
studies
conducted
by
Miltner
et
al.
(
1987),
different
oxidants
were
tested
for
their
ability
to
remove
alachlor
in
water.
The
oxidants
were
O3
,
Cl2
,
ClO2
,
H2
O2
,
and
KMnO4
.
Table
3.5
shows
the
chemical
oxidation
results
using
different
doses
of
the
oxidants,
alachlor
concentration,
and
contact
time.
Only
ozone
was
found
to
remove
alachlor,
with
removal
efficiencies
ranging
from
75
to
97%
for
distilled
water,
groundwater
and
surface
water.
The
remaining
oxidants
such
as
ClO2
,
H2
O2
,
and
KMnO4
were
largely
ineffective
in
removing
alachlor
in
distilled
water
samples.
In
surface
water
samples,
low
removal
efficiencies
were
exhibited
by
Cl2
and
ClO2
.

Table
3.5.
Removal
of
Alachlor
by
Chemical
Oxidation
Oxidant
Oxidant
dose
(
mg/
L)
Alachlor
Concentration
(
µ
g/
L)
Contact
Time
(
Hr)
%
Removal
Ozone
6.9
139
(
DW)*
0.22
95
2.6­
9.3
145
(
GW)**
0.22
79
­
96
2.3­
13.7
0.39
­
5.0
(
SW)***
0.22
75
­
97
Chlorine
4.0­
6.0
31
­
61
(
SW)
2.5
­
5.83
0
­
5
ClO2
3.0
61
(
SW)
2.5
9
10.0
58
(
DW)
22.3
0
H2O2
10.0
58
(
DW)
22.3
0
KMnO4
10.0
58
(
DW)
22.3
0
*
From
Miltner
et
al.,
1987
*
DW=
distilled
water
**
GW=
Groundwater
***
SW=
Surface
water
The
oxidation
of
glyphosate
(
herbicide)
by
different
disinfection
chemicals
from
pilot­

23
plant
studies
was
reported
by
Speth
(
1993).
Glyphosate
concentration
(
796
µ
g/
L)
was
reduced
by
chlorine
(
2.1
mg/
L)
after
7.5
minute
contact
time
to
below
detection
limits
(<
25
µ
g/
L).
Ozone
destroyed
glyphosate
(
840
to
900
µ
g/
L)
within
5
to
7
minutes
at
applied
dosages
of
1.9
and
2.9
mg/
L.
In
the
bench­
scale
studies,
treatments
with
ClO2
,
KMnO4
and
H2
O2
were
less
successful
in
pesticide
(
glyphosate)
oxidation.

The
effect
of
chlorination
on
pesticides
was
also
evaluated
at
full­
scale
treatment
plants
in
Ohio
(
Miltner
et
al.,
1989).
Three
treatment
plants
in
Tiffin
District,
Fremont,
and
Bowling
Green,
Ohio,
generally
used
up
to
13
mg/
L
Cl2
(
especially
during
runoff
season)
and
provided
in­
plant
contact
time
of
less
than
12
hours.
The
percent
removal
data
for
those
pesticides
initially
present
at
parts
per
billion
levels
(
µ
g/
L)
are
summarized
in
Table
3.6.
For
atrazine,
cyanazine,
simazine,
alachlor,
metolachlor,
and
linuron,
the
removal
efficiencies
were
either
zero
or
extremely
low.
Slight
removal
was
observed
for
carbofuran.
Up
to
98
%
removal
was
reported
for
metribuzin.
However,
according
to
the
investigators,
this
high
removal
efficiency
may
be
partly
attributed
to
sample
preparation
in
which
no
reducing
agent
was
added
to
stabilize
the
samples.
Thus,
it
was
possible
that
chlorination
could
have
continued
for
days
prior
to
analysis
of
the
samples
collected.

Table
3.6.
Removal
of
Pesticides
Associated
with
Chlorination
at
Full­
Scale
Treatment
Plants.

Pesticide
Initial
Concentration
(
µ
g/
L)
%
Removal
Atrazine
1.59
­
15.5
(
SW)
0
Cyanazine
0.66
­
4.38
(
SW)
0
Metribuzin
0.10
­
4.88
(
SW)
24
­
98*

Simazine
0.17
­
0.62
(
SW)
0
­
7
Alachlor
0.94
­
7.52
(
SW)
0
­
9
Metolachlor
0.98
­
14.1
(
SW)
0
­
3
Linuron
0.47
(
SW)
4
Carbofuran
0.13
(
SW)
24
From
Miltner
et
al.
(
1989)
*
Metribuzin
removal
may
be
the
result
of
sample
storage
without
oxidant
quenching.
Similar
removals
in
water
treatment
plants
may
not
be
expected.
SW=
surface
water
3.7(
c)
Carbon
Adsorption
Adsorption
water
treatment
processes
are
predominately
used
for
control
of
taste
and
odor
as
well
as
removing
synthetic
organic
compounds,
toxic
metals,
and
chlorine.
Sorption
is
a
process
of
reversible
physicochemical
binding
of
the
substance
on
the
sorbent
(
e.
g.,
colloid
or
activated
carbon).
Mechanisms
controlling
sorption
are
dependent
on
physical
processes
such
as
electrostatic
attraction
(
dipole­
dipole
interactions,
dispersion
interactions
(
van
der
Waals
forces),
and
hydrogen
bonding)
or
chemisorption
(
J.
M.
M.
Consulting
Engineers,
1985).
Non­
linear
24
equilibrium
models
such
as
the
Langmuir
and
Freundlich
models
have
been
used
to
predict
adsorption
potential
of
organic
contaminants.
Compounds
with
a
high
Freundlich
coefficient
have
sorption
affinity
to
activated
carbon.
Another
approach
for
predicting
adsorption
is
the
Polanyi
potential
theory.

Granular
activated
carbon
(
GAC)
and
powdered
activated
carbon
(
PAC)
are
common
sorbents.
Activated
carbon
is
composed
of
expanded
layers
of
graphite,
which
leads
to
an
extremely
high
surface
area
to
mass
ratio
for
sorption
(
J.
M.
M.
Consulting
Engineers,
1985).
The
main
difference
between
GAC
and
PAC
is
the
particle
size;
PAC
has
smaller
particles
when
compared
to
GAC.
Other
less
common
sorbents
are
activated
aluminum,
silica
gel,
synthetic
aluminosilicates,
polymeric
resins,
and
carbonized
resins.
GAC
is
used
as
a
filter
adsorber
for
taste
and
odor
control,
and
post­
filter
adsorbers
are
designed
for
synthetic
organic
removal.
In
contrast,
PAC
is
added
within
conventional
treatment
systems
before
or
during
the
coagulation/
flocculation
and
sedimentation
treatment
process.

The
adsorption
capacity
of
activated
carbon
to
remove
pesticides
is
affected
by
concentration,
temperature,
pH,
competition
from
other
contaminants
or
natural
organic
matter,
organic
preloading,
contact
time,
mode
of
treatment,
and
physical/
chemical
properties
of
the
contaminant.
GAC
column
effectiveness
is
also
a
function
of
the
water
loading
rate
and
empty
bed
time,
whereas
PAC
effectiveness
is
also
a
function
of
the
carbon
dosage.
Generally,
activated
carbon
has
an
affinity
for
contaminants
that
are
hydrophobic
(
low
solubilities),
although
other
parameters
such
as
density
and
molecular
weight
can
be
important.

Isotherm
constants
have
been
reported
to
be
valuable
for
predicting
whether
activated
carbon
adsorbs
a
particular
pesticide
(
Speth
and
Miltner,
1990;
Speth
and
Adams,
1993).
They
reported
that,
in
general,
compounds
with
a
Freundlich
coefficients
on
activated
carbon
greater
than
200
ug/
g
(
L/
ug)
1/
n
would
be
amendable
to
removal
by
carbon
sorption.

3.7(
c)
1
Powdered
Activated
Carbon
(
PAC)

Miltner
et
al.
(
1987,1989)
studied
the
removal
of
atrazine
and
alachlor
using
PAC.
PAC
doses
were
selected
to
reflect
the
range
commonly
used
by
PWSs
for
taste
and
odor
control.
Both
jar
and
full­
scale
treatment
tests
conducted
using
surface
water
samples
containing
other
synthetic
organic
contaminants
indicated
that
atrazine
and
alachlor
could
be
adequately
sorbed
to
activated
carbon.
The
observed
removal
was
attributed
to
adsorption
because
previous
studies
indicated
that
conventional
treatment
was
ineffective
in
removing
these
pesticides
in
the
raw
water.
Only
the
results
of
the
full­
scale
treatment
effects
will
be
presented
here.
Table
3.7
summarizes
the
doses,
PAC
types
(
WPH
Calgon
and
Hydrodarco),
water
source,
and
mean
concentrations
of
the
two
pesticides.
The
percent
removal
ranged
from
28%
to
87%
for
atrazine
and
33%
to
94%
for
alachlor.
As
the
PAC
dose
increased,
sorption
removal
efficiencies
likewise
increased.

25
Table
3.7.
Removal
of
Atrazine
and
Alachlor
Using
PAC
during
Full­
Scale
Treatment.

PAC*
(
dose,
mg/
L)
Water
Source**
Co
(
µ
g/
L)
%
Removal
Atrazine
Alachlor
Atrazine
Alachlor
WPH
(
2.8)
Sandusky
River
(
C)
7.83
1.67
28
33
WPH
(
3.6)
Sandusky
River
(
C)
2.61
1.49
38
36
WPH
(
8.4)
Sandusky
River
(
R)
12.05
2.84
35
41
WPH
(
11)
Sandusky
River
(
R)
4.43
2.53
41
41
HDB
(
18)
Maumee
River
(
R)
8.11
8.21
67
62
HDB
(
33)
Maumee
River
(
R)
2.39
0.97
87
94
From
Miltner
et
al.,
1987
and
Miltner
et
al.,
1989.
*
PAC
type:
WHP
=
WHP
Calgon
and
HDB
=
Hydrodarco,
ICI,
America
**
(
C)
=
Clarified
Water;
(
R)
=
Raw
Water
The
PAC
dose
required
to
reduce
the
pesticide
concentration
to
a
predetermined
value
in
a
jar
test
using
distilled
water
could
be
different
compared
to
using
a
natural
water
from
a
treatment
plant.
The
difference
could
be
due
to
the
presence
of
other
solutes
and
treatment
chemicals
in
natural
water
that
can
compete
with
the
pesticides
for
sorption
sites.
Figure
3.1
shows
that
the
activated
carbon
adsorptive
capacity
for
parathion,
2,4,5­
T
ester,
lindane,
and
dieldrin
in
Little
Miami
River
water
is
more
than
50%
lower
than
that
in
distilled
water
(
Najm
et
al.,
1991).

26
Figure
3.1.
PAC
Doses
Required
to
Remove
99%
of
the
Pesticide
from
Jar
and
Plant
Tests.
Initial
concentration
of
each
pesticide
is
10
µ
g/
L
(
Data
from
Najm
et
al,
1991).
Jar
Test:
PAC
dose
in
jar
tests
(
distilled
water)
determined
from
1
hour
contact
time.
Plant
Test:
PAC
dose
in
plant
test
(
river
water)
determined
using
conventional
treatment
and
activated
carbon
sorption.

3.7(
c)
2
Granular
Activated
Carbon
(
GAC)

Like
PAC,
GAC
is
also
known
for
adsorbing
a
wide
variety
of
organic
compounds
and
pesticides.
The
performance
of
GAC
in
removing
pesticides
from
raw
water
has
been
demonstrated
by
the
studies
of
Miltner
et
al.
(
1989)
who
used
pesticides
belonging
to
triazine,
acetanilide,
and
dinitroaniline
classes.
The
carbon
was
in
operation
for
30
months
before
sampling.
As
shown
in
Table
3.8,
two
types
of
GAC,
Calgon
Filtrasorb
300
and
Filtrasorb
400,
were
used.
Relative
to
the
initial
concentrations
of
the
pesticides,
the
percent
removal
of
the
two
acetanilide
pesticides
(
72
­
98%)
was
higher
than
those
of
the
triazine
pesticides
(
47
­
62%).
The
highest
removal
efficiency
(>
99%)
by
Filtrasorb
400
was
reported
for
pendimethalin.

Table
3.8.
Removal
of
Pesticides
by
Granulated
Activated
Carbon
Adsorption.

Pesticide
GAC
Co
(
µ
g/
L)
%
Removal
(
Triazine)

Atrazine
Calgon
Filtrasorb
300*
4.83
(
SW)+
47
27
Table
3.8.
Removal
of
Pesticides
by
Granulated
Activated
Carbon
Adsorption.

Pesticide
GAC
Co
(
µ
g/
L)
%
Removal
Cyanazine
Calgon
Filtrasorb
300*
1.62
(
SW)+
67
Metribuzin
Calgon
Filtrasorb
300*
0.89
(
SW)+
57
Simazine
Calgon
Filtrasorb
300*
0.39
(
SW)+
62
(
Acetamilide)

Alachlor
Calgon
Filtrasorb
300*
3.70
(
SW)+
72
Metolachlor
Calgon
Filtrasorb
300*
5.60
(
SW)+
56
Pendimethalin
(
dinitroaniline)
Calgon
Filtrasorb
300*
0.20
(
SW)+
>
99
From
Miltner
et
al.,
1989
&
Milner
et
al.,
1987
*
30
month­
old
carbon,
bed
depth
=
1.5
ft,
loading
=
4
gpm/
ft3,
EBCT
=
2.81
min.
+
SW=
clarified
Sandusky
River
water
(
Surface
Water)

Based
on
the
data
of
Miller
and
Kennedy
(
1995)
for
two
triazine
herbicides
and
a
transformation
product
in
reservoir
and
drinking
waters,
activated
carbon
treatment
actually
employed
in
different
municipalities
could
have
mixed
results.
As
presented
in
Table
3.9,
GAC
adsorption
in
Creston,
Lake
Park,
and
Oscealo,
Iowa
decreased
the
concentrations
of
atrazine,
cyanazine,
and
desethylatrazine
in
the
treated
water.
But
in
Fairfield,
cyanazine
was
detected
in
the
drinking
water
(
close
to
detection
limit)
but
was
not
found
in
the
water
reservoir.
In
Lake
Park,
desethylatrazine
was
detected
in
the
drinking
water
but
not
in
the
reservoir
water.
It
is
difficult
to
know
whether
the
results
for
Fairfield
and
Lake
Park
are
somehow
related
to
sampling
and
analytical
deficiencies
or
possible
breakthrough
of
cyanazine
and
desethlyatrazine
from
the
GAC
column.
The
sampling
time
and
schedule
for
the
reservoir
and
drinking
waters
have
to
also
be
considered.

Table
3.9.
Water
Supply
Sources
Treated
with
GAC
and
Herbicide
Concentrations
in
Drinking
Water
City/
Town
Water
Supply
Source
Atrazine*
Drinking
Reservoir
Water
Water
Cyanazine*
Drinking
Reservoir
Water
Water
Desethylatrazine*
Drinking
Reservoir
Water
Water
Creston
Twelve
Mile
Lake
0.35
0.46
0.11
0.16
0.11
0.16
Fairfield
Fairfield
Reservoir/
Wells
<
0.1
<
0.1
0.11
<
0.1
<
0.1
<
0.1
Lake
Park
Silver
Lake
0.28
0.30
0.22
0.3
0.3
<
0.1
Lenox
Lenox
East
Reservoir/
Twelve
Mile
Lake
0.27
0.34
0.36
0.68
<
0.1
0.10
Osceola
West
Lake
1.3
2.4
2.8
4.7
0.22
0.42
*
Concentrations
in
µ
g/
L
28
3.7(
c)
3
Biologically
Active
Carbon
(
BAC)

BAC
is
a
process
of
removing
soluble
organic
compounds
in
raw
water
through
a
combination
of
adsorption
to
GAC
and
biological
oxidation
by
the
microorganisms
present
in
the
activated
carbon.
The
aerobic
microbial
growth
in
the
activated
carbon
filters
is
enhanced
by
providing
sufficient
dissolved
oxygen
into
the
water
ahead
of
the
GAC
beds.
If
organic
compounds
in
the
raw
water
are
not
readily
biodegradable
or
recalcitrant
substances
are
present,
ozone
is
usually
added
ahead
of
the
carbon
filters.
Consequently,
preozonation
is
sometimes
used
to
convert
larger,
less
biodegradable
organic
compounds
into
smaller,
more
easily
metabolizable
molecules.
As
a
result
of
biological
oxidation,
the
activated
carbon
is
not
rapidly
saturated
with
biorefractory
compounds,
and
thus,
the
adsorber
bed
service
life
is
extended.
Generally
all
GAC
columns
are
biofilters
because
GAC
will
remove
the
disinfectant
in
the
top
few
inches
of
the
bed.
No
studies
or
reports
were
found
to
provide
information
on
the
extent
of
removal
of
pesticides
passing
through
BAC
adsorber
columns.
No
reference
was
also
found
that
distinguishes
between
adsorption
and
biodegradation.

3.7(
d)
Membrane
Treatment
Membranes
are
used
in
water
treatment
for
desalinization,
specific
ion
removal,
removal
of
color,
organics,
nutrients,
and
suspended
solids.
Membranes
are
used
in
reverse
osmosis
(
RO),
electrodialysis
(
ED),
ultrafiltration,
microfiltration,
and
nanofiltration
(
J.
M.
M.
Consulting
Engineers,
1985
and
USEPA,
1989).
Ultrafilitration
is
considered
a
filtering
technique
because
it
is
designed
to
exclude
compounds
with
molecular
weights
greater
than
500
grams/
mole.
In
contrast,
RO
and
ED
are
designed
to
use
a
semipermeable
membrane
as
a
diffusion
barrier
for
dissolved
constituents
in
the
water.
Electrodialysis
is
controlled
by
electrostatic
attraction
of
ionic
compounds
to
anionic
and
cationic
electrodes
across
a
semipermeable
membrane.
Reverse
osmosis,
however,
is
controlled
by
hydrostatic
pressure
(
300
to
1000
psi)
to
drive
feedwater
through
a
semipermeable
membrane.
Membranes
are
typically
composed
of
cellulose
acetate,
polyamide
membranes,
and
thin
film
composites.
Membrane
configurations
for
RO
are
spiral
wound
and
hollow
fine
fiber
membrane.
The
effectiveness
of
RO
is
dependent
on
membrane
composition,
physicochemical
properties
of
raw
water,
pressure,
and
membrane
treatment
conditions.
Electrodialysis
is
affected
by
amount
of
DC
current.

3.7(
d)
1
Reverse
Osmosis
(
RO)

The
use
of
semipermeable
membranes
during
RO
treatment
has
been
demonstrated
to
remove
organic
pollutants
and
pesticides
from
contaminated
water.
The
membranes
normally
used
in
the
past
were
either
cellulose
acetate
(
CA)
or
polyamide.
Later,
a
new
type
of
membrane
called
thin
film
composites
was
introduced.
These
membranes
could
be
produced
from
a
variety
of
polymeric
materials
that
were
formed
in­
situ
or
coated
onto
the
surface
of
an
extremely
thin
polysulfone
support.
Examples
are
NS­
100
(
cross­
linked
polyethylenimine
membrane),
FT­
30
(
cross­
linked
polyamide
that
contains
carboxylate
group),
and
DSI
(
modified
polyalkene
on
a
polysulfone
base
with
non­
woven
polyester
backing).

A
short­
term
laboratory
test
conducted
by
Chian
(
1975)
demonstrated
that
NS­
100
29
membrane
was
able
to
remove
97.8%
of
atrazine
compared
to
84.0%
removal
using
CA
membrane.
Since
then,
other
studies
by
several
investigators
(
Eisenberg
and
Middlebrooks,
1986;
Lykins
et
al.,
1988;
Miltner
et
al.,
1989;
Fronk
et
al.,
1990)
generally
indicated
that
thin
film
composite
membranes
have
superior
performance
in
removing
pesticides
compared
to
those
of
CA
and
polyamide
membranes.
For
instance,
as
summarized
in
Table
3.10,
the
percent
removal
of
linuron
from
groundwater
samples
was
zero
using
CA,
57%
using
polyamide,
and
99%
using
thin
film
composite
DSI.
Similar
results
were
obtained
for
alachlor
in
surface
water
samples:
70%
removal
using
CA,
77%
using
polyamide,
and
100%
by
thin
from
composite
FT­
30.
The
high
removal
efficiencies
for
a
wide
range
of
initial
concentrations
(
ppb
to
ppm)
are
presented
in
Table
3,10.
The
reported
data
pertain
to
pesticides
belonging
to
triazine,
acetanilide,
organochlorine,
urea
derivative,
carbamate,
and
organophosphorus
classes.
For
individual
compounds
in
each
class
and
others
[
that
include
1,2­
dichloropropane,
captan,
trifluralin.
and
aldicarb
transformation
products
(
sulfoxide
and
sulfone)],
the
percent
removal
data
in
surface
water
(
SW)
and
groundwater
(
GW)
are
presented
in
Appendix
A.

Table
3.10.
Removal
Efficiencies
of
RO
Membranes
for
Different
Pesticide
Classes
Pesticide
Class
Cellulose
Acetate
(
CA)
Polyamide
Thin
film
Composite
Triazine
23
­
59
68
­
85
80
­
100
Acetanilide
70
­
80
57
­
100
98.5
­
100
Organochlorine
99.9
­
100
100
Organophosphorus
97.8
­
99.9
98.5
­
100
Urea
Derivative
0
57
­
100
99
­
100
Carbamate
85.7
79.6
­
93
>
92.9
Membranes
operated
with
a
lower
pressure
can
also
be
used
in
water
treatment
plants.
Fronk
et
al.
(
1990)
conducted
an
evaluation
of
removing
certain
pesticides
from
groundwater
using
thin
film
composite
membranes.
The
results
are
shown
in
Table
3.11.
Excellent
removal
(~
100%)
of
organochlorine
pesticides
(
chlordane,
heptachlor
and
methoxychlor)
and
an
acetanilide
compound
(
alachlor)
was
obtained.
The
removal
of
dibromochloropropane
was
not
high
and
ethylene
dibromide
was
not
removed
at
all.

Table
3.11.
Removal
of
Pesticides
Using
Ultrafiltration
Pesticide
Membrane
Co
(
ug/
L)
%
Removal
Organochlorine
Chlordane
Thin
Film
Composite
<
100
(
GW)
~
100
Heptachlor
Thin
Film
Composite
<
100
(
GW)
~
100
Methoxychlor
Thin
Film
Composite
<
100
(
GW)
~
100
30
Table
3.11.
Removal
of
Pesticides
Using
Ultrafiltration
Pesticide
Membrane
Co
(
ug/
L)
%
Removal
VOC
Dibromochloropropane
Thin
Film
Composite
<
100
(
GW)
19
­
52
Ethylene
dibromide
Thin
Film
Composite
<
100
(
GW)
~
0
Others
Alachlor
Thin
Film
Composite
<
100
(
GW)
~
100
From
Fronk
et
al.,
1990
3.7(
d)
2
Nanofiltraton
(
NF)

Another
membrane
technique
is
nanofiltration
or
NF.
The
membrane
employed
is
somewhat
 
more
loose 
and
the
process
is
operated
with
lower
effective
pressure
and
without
significant
changes
in
water
salinity.
A
pilot
plant
study
reported
by
Hofman
et
al.
(
1996)
indicated
promising
removal
results,
as
summarized
in
Table
3.12.
Using
four
different
membranes,
up
to
about
90%
of
diuron
can
be
removed
while
more
than
90%
removal
can
be
achieved
for
atrazine
and
simazine.
Bentazon
had
a
removal
efficiency
of
95%,
the
highest
in
the
study.

Table
3.12.
Removal
of
Pesticides
Using
Nanofiltration
Membranes
Pesticide
Membrane
Co
(
µ
g/
L)
%
Removal
Atrazine
(
triazine)
4
different
membranes
not
given
80­
98
Simazine
(
triazine)
4
different
membranes
not
given
63­
93
Diuron
(
urea)
4
different
membranes
not
given
43
 
87
Bentazone
(
miscellaneous)
4
different
membranes
not
given
96­
99
From
Hofman
et
al,
1996
3.7(
d)
3
Integrated
membrane/
adsorbent
systems
Microfiltration
(
MF)
with
porosity
nominally
>
0.1
µ
m
and
ultrafiltration
(
UF)
with
porosity
.
0.01
µ
m
are
sometimes
combined
with
adsorbents
such
as
PAC
to
form
an
intergrated
system
that
can
be
effective
in
removing
pesticides.
An
integrated
system
UF/
PAC
system
was
reported
by
Anselme
et
al
(
1991)
to
effectively
remove
some
pesticides.
Jack
and
Clark
(
1998)
found
that
a
UF/
PAC
(
10
mg/
L
PAC)
system
was
capable
of
removing
cyanazine
by
70%
and
atrazine
by
61%.
With
higher
PAC
levels,
better
results
can
be
obtained.
The
removal
of
atrazine
was
increased
from
57%
at
5
mg/
L
to
89%
at
20
mg/
L
PAC.
(
Claire
et
al,
1997).

It
would
be
expected
that
the
integrated
membrane/
adsorbent
system
will
lead
to
greater
adsorption
with
increase
in
the
adsorbent
time.
Other
factors
that
can
influence
the
final
degree
of
31
adsorption
include
temperature,
pH
(
for
ionizable
pesticides),
PAC
type
and
dose,
and
competitive
adsorption
from
dissolved
natural
organic
materials
and
other
contaminants.

3.7(
e)
Corrosion
Control
Treatments
Corrosion
control
is
used
in
water
treatment
to
limit
interaction
of
the
treated
water
with
pipes
and
water
conduit
systems.
The
principal
processes
for
corrosion
control
are
regulation
of
pH
and
addition
of
corrosion
inhibitors
(
J.
M.
M.
Consulting
Engineers,
1985
and
USEPA,
1989).
The
adjustment
of
pH
through
the
addition
of
lime
or
sodium
hydroxide
is
required
by
EPA
to
inhibit
metal
dissolution
(
e.
g.,
lead)
in
finished
water.
Chemical
control
agents
(
such
as
zinc
orthophosphate,
silicates,
polyphosphates)
are
added
to
encourage
mineral
coating
(
zinc
carbonates
or
iron
silicates)
on
the
surface
of
the
pipes,
which
prevents
corrosion
of
pipes.

Control
of
pipe
corrosion
in
potable
distribution
systems
can
be
achieved
by
pH
or
alkalinity
adjustment
and
application
of
corrosion
inhibitors.
So
far,
no
studies
have
been
reported
nor
found
that
would
suggest
that
pesticides
detected
in
raw
or
untreated
water
are
removed
or
reduced
during
corrosion
control
operations
in
the
treatment
plants.
Whether
calcium
carbonate
deposition
or
calcium
reaction
with
phosphate
inhibitors
can
ultimately
lead
to
removal
of
pesticides
in
water
remains
to
be
seen.
The
pH
adjustment
may
have
an
impact
on
pesticides
susceptible
to
pH
dependent
hydrolysis.

3.7(
f)
Aeration/
Air
Stripping
Aeration
and
air
stripping
are
water
treatment
processes
associated
with
gas
transfer
in
drinking
water.
These
processes
have
been
used
to:
inject
disinfectants
(
O3
and
ClO2
)
in
finished
water,
inject
O2
into
feed
water
to
accelerate
oxidation,
and
to
remove
ammonia
(
NH3
)
and
volatile
organic
compounds
(
J.
M.
M.
Consulting
Engineers,
1985
and
USEPA,
1989).
Gas
exchange
is
accomplished
using
gas
dispersion
methods
(
bubbling
air
or
mechanical
mixing)
or
specially
designed
gas­
liquid
contact
equipment
(
e.
g.,
packed
towers,
cross­
flow
towers,
and
spray
towers).
The
Henry s
Law
Constant,
the
ratio
of
pesticide
concentrations
between
gas
and
liquid
phases
at
equilibrium,
has
been
used
to
predict
the
effectiveness
of
aeration
and
air
stripping
techniques
on
the
removal
of
organic
compounds.

The
removal
of
volatile
organic
contaminants
and
pesticides
can
be
accomplished
by
using
packed
towers,
spray
towers,
or
agitated
diffused
gas
vessels.
Qualitatively,
the
greater
the
Henry s
Law
Constant
(
H)
of
a
chemical
or
pesticide,
the
more
easily
the
chemical
can
be
removed
from
the
solution
or
aqueous
phase.
Based
on
a
study
by
McCarty
(
1987),
a
chemical
with
a
H
value
of
1
x
10­
3
atm
m3
mole­
1
is
amenable
to
removal
by
aeration.
Pesticides
with
H
values
slightly
lower
than
1
x
10­
3
atm
m3
mole­
1
may
be
still
be
removed,
but
more
energy
would
be
required.
In
addition,
relatively
higher
towers
and
greater
air/
water
ratios
would
be
needed
if
a
packed
tower
stripper
is
used.
Examples
of
pesticides
that
could
be
removed
by
air
stripping
are
those
belonging
to
volatile
organic
chemical
(
VOC)
class:

Pesticide
H
(
atm
m3
mole­
1)

32
Dibromochlorpropane
2.78
x
10­
3
1.80
x
10­
3
0.67
x
10­
3
1,2
­
Dichloropropane
Ethylene
dibromide
3.8
Pesticide
Transformation
Associated
with
Certain
Treatment
Processes
Most
of
the
treatment
processes
that
have
been
demonstrated
to
significantly
remove
pesticides
from
raw
water
involve
physical
phase
separations
in
which
the
pesticides
are
transferred
from
the
solution
phase
and
then
trapped
or
concentrated
in
the
solid
matrix
such
as
filters,
activated
carbon
or
membranes.
However,
certain
treatment
operations
ultimately
lead
to
loss
of
the
parent
pesticides
through
chemical
reactions.
Thus,
the
pesticides
are
converted
to
another
chemical(
s)
as
transformation
products.
Transformations
typically
occur
when
a
treatment
chemical
is
introduced
and
subsequently
significantly
changes
the
acid­
base
character
or
facilitates
the
redox
processes
in
the
water.
During
lime
softening
and
disinfection
with
chemical
oxidants,
pesticides
could
be
transformed
into
other
process
products.
Some
byproducts
resulting
from
ozonation
of
certain
pesticides
have
been
reported
in
a
recent
preliminary
literature
review
on
treatment
of
pesticide­
contaminated
raw
water
(
Pisigan,
1998).
In
many
cases,
these
transformation
are
considered
important
by
OPP.

Pesticides
are
susceptible
to
microbially­
mediated
oxidation
in
terrestrial
and
aquatic
environments.
This
degradation
pathway
will
ultimately
lead
to
the
formation
of
CO2
with
the
formation
of
intermediate
by­
products.
In
many
cases
these
transformation
products
are
identified
as
part
of
the
OPP
risk
assessment
process
since
extensive
animal,
plant,
and
soil
metabolism
studies
are
required
to
be
submitted
by
the
registrant
and
are
reviewed
by
the
Agency.
Similar
degradation
pathways
and
transformation
products
are
expected
from
chemical
oxidation
through
the
water
treatment
disinfection
process.
Preliminary
data
from
the
EPA­
USGS
pilot
reservoir
monitoring
project
indicate
that
water
treatment
processes
have
an
impact
on
the
recovery
of
organophosphates
and
some
other
pesticides
in
treated
water
when
compared
to
spiked
raw
water
samples
(
personal
communication
Joel
Blomquist
at
USGS
and
James
Carleton
at
OPP/
EPA).
Low
or
non­
existent
analytical
recoveries
of
some
pesticides
(
especially
organophosphates)
occurred
in
spiked
treated
water
samples,
presumably
due
to
oxidation
by
residual
chlorine.
However,
some
oxidative
transformation
products
(
oxons,
sulfoxides,
sulfones,
oxon­
sulfones,
etc.)
of
certain
organophosphates
(
e.
g.
methyl­
paraoxon,
ethyl­
paraoxon,
fenamiphos
sulfone,
terbufos
oxon­
sulfone,
azinphos­
methyl
oxon
)
when
spiked
into
treated
water
appear
to
have
better
analytical
recoveries
than
their
respective
parent
compounds.
The
preliminary
recovery
data
suggest
that
organophosphates
may
be
oxidized
in
treated
water
to
form
relatively
stable,
toxic
transformation
products.

3.8(
a)
Transformation
Induced
by
Lime
Softening
Basic
chemicals
such
as
slaked
calcium
oxide
are
added
during
lime
softening
to
increase
the
pH
of
the
water
to
about
10
to
11.
At
this
alkaline
condition,
pesticides
that
undergo
alkaline
hydrolysis
would
be
expected
to
be
transformed.
Examples
of
pesticides
that
are
known
to
be
hydrolytically
unstable
at
high
pH
values
are
demeton­
S­
methyl,
carbofuran,
captan,
and
33
methomyl.
During
high
lime
treatment
for
2
hours,
van
Rensburg
et
al.
(
1978)
observed
that
demeton­
S­
methyl
was
apparently
hydrolyzed
at
pH
10.5
yielding
about
70%
removal
of
demeton­
S­
methyl
present
in
the
raw
water
at
an
initial
concentration
of
3100
ug/
L.
In
conducting
a
study
on
the
adsorption
capacity
of
GAC
for
synthetic
organics,
Speth
and
Miltner
(
1998)
reported
that
methomyl
had
to
be
tested
with
a
pH
of
2.8
to
maintain
stability
because
methomyl
rapidly
degraded
over
a
wide
pH
range.
This
implies
that
at
highly
alkaline
conditions
methomyl
will
undergo
very
fast
hydrolysis.
According
to
fate
properties
summarized
in
Table
3.13,
the
pH
9
hydrolysis
half­
lives
of
carbofuran
and
captan
are
0.625
day
and
0.00056
day,
respectively.
Carbofuran
was
found
to
be
100%
removed
during
water
softening
at
pH
10.9
and
11.1
in
a
full­
scale
treatment
tests
conducted
by
Miltner
et
al.
(
1989).
Based
on
Nanogen
International
(
1975),
the
possible
hydrolysis/
hydroxylation
products
are
3­
hydroxycarbofuran
and
carbofuran
phenol.
Carbofuran
has
been
shown
to
hydryolze
under
alkaline
conditions
to
form
carbofuran­
7­
phenol
as
the
major
degradation
product
(
USEPA,
1999).
Thus,
the
possible
softening
reaction
involving
carbofuran
may
be
represented
as
follows:

OHcarbofuran
Y
YYYYY
Y
carbofuran­
7­
phenol
+
3­
hydroxycarbofuran
pH
10­
11
The
extent
of
the
alkaline
hydrolysis
and
the
formation
of
other
products
are
expected
to
be
affected
by
contact
time
and
water
quality
characteristics.

Other
pesticides
with
short
hydrolysis
half­
lives
(<
1
day)
at
pH
9.0
are:
desmedipham,
dicofol,
iprodione,
thiodicarb,
and
2­
hydroxypropyl
methanethiosulfonate.
These
pesticides
potentially
can
be
removed
and
transformed
by
basic
hydrolysis
during
softening.

3.8(
b)
Transformation
Caused
by
Chemical
Disinfection/
Oxidation
Chemical
disinfection
is
widely
applied
to
destroy
disease­
causing
microorganisms
and
thus
make
the
treated
water
safe
for
human
consumption.
More
than
95%
of
surface
water
treatment
facilities
serving
501
to
more
than
100,000
persons
employ
disinfection.
For
the
same
ranges
of
population
served,
at
least
80%
of
the
groundwater
treatment
plants
use
disinfection
to
get
rid
of
pathogenic
microbes.
The
chemicals
used
as
disinfectants
are
chlorine
and
chlorine
compounds,
ozone,
iodine,
and
bromine.
The
most
common
form
of
disinfection
practiced
in
the
United
States
is
the
addition
of
chlorine
to
water.
Ozone
is
a
widely
used
disinfectant
in
Europe
and
is
also
becoming
an
alternative
chemical
oxidant
and
disinfectant
in
some
water
treatment
facilities
in
the
United
States.
Both
chlorine
and
ozone
are
strong
oxidizing
agents
that
react
with
a
variety
of
organic
compounds
and
pesticides
and
convert
the
compounds
to
disinfection
by­
products
that
could
be
present
in
the
treated
water.

3.8(
b)
1
Chlorination
Byproducts
Certain
pesticides
belonging
to
organophosphate
and
carbamate
classes
are
susceptible
to
transformation
during
chlorination
of
raw
water.
Magara
et
al
(
1984)
have
shown
that
organophosphate
pesticides
containing
P=
S
bonds
were
easily
degraded
by
chlorine
and
produced
34
oxons
(
P=
O
bond)
as
a
primary
byproduct.
In
a
previous
study
(
Aizawa
and
Magara,
1992),
pesticides
with
thiono
group
(­
P=
S­
O­)
such
as
diazinon,
chlorpyrifos­
methyl,
fenthion
(
MPP),
pyridaphenthion.
and
those
containing
dithio
group
(­
P=
S­
S­)
such
as
malathion,
penthoate
(
PAP),
and
ethyl
p­
nitrophenyl
benzenethionophosphate
(
EPN)
were
reported
to
yield
oxons
and
other
chlorination
degradation
products.
For
instance,
diazinon
can
be
converted
to
diazoxon
which
may
be
further
transformed
to
chlorinated
products
as
shown
below:

Cl2
Diazinon
YYYY
Diazoxon
9
diethyl
phosphoric
acid
9
dichloroacetic
acids
trichloroacetic
acids
However,
diazoxon
may
remain
stable
for
some
time
after
it
is
formed.
In
an
experiment
in
which
chlorine
was
present
at
levels
above
5
mg/
L
in
an
aqueous
solution
of
diazinon
(
5
µ
g/
L),
diazoxon
was
observed
to
be
highly
stable
against
chlorine
even
after
48
hours
(
Magara,
1994).

Organophosphate
pesticides
may
also
be
transformed
to
the
oxon
through
biochemical
reactions
in
mammalian
tissues.
Whether
formed
in
mammalian
tissues
or
introduced
directly
via
drinking
water,
there
is
a
concern
with
the
formation
of
oxons
because
it
is
widely
known
that
oxon
forms
of
organophosphates
are
more
potent
acetylcholinesterase
inhibitors
than
the
parent
form
(
Amdur
et.
al.,
1991).
The
oxon
intermediate
is
readily
hydrolyzed
in
mammalian
systems.

Certain
carbamate
pesticides
may
also
react
with
chlorine
to
produce
disinfection
byproducts.
In
a
chlorination
study
conducted
by
Mason
et
al
(
1990),
both
aldicarb
and
methomyl
were
demonstrated
to
be
transformed
by
an
electrophillic
ionic
attack
by
hypochlorous
acid
(
HOCl),
which
is
formed
by
chlorine
hydrolysis
in
water.
The
reaction
between
methomyl
and
HOCl
was
found
to
be
several
orders
of
magnitude
faster
than
the
reaction
between
aldicarb
and
HOCl.
Sodium
chloride
concentration
(
reflecting
ionic
strength)
and
pH
were
shown
to
affect
the
chlorination
rates.
The
chlorination
of
aldicarb
may
be
described
by
the
following
reaction:

HOCl
Aldicarb
YYYY
Y
Aldicarb
sulfoxide
+
Aldicarb
sulfone
+
Aldicarb
Oxime
+
Aldicarb­
sulfoxide
Oxime
+
Aldicarb
Nitrile
+
sulfur­
containing
alcohol
No
product
analysis
was
done
for
the
methomyl­
HOCl
reaction.
The
result
of
a
preliminary
bioassay
using
Daphnia
magna
to
compare
the
toxicity
of
aldicarb
and
chlorination
by­
products
indicated
that
the
by­
products
were
less
toxic.

A
thiocarbamate,
thiobencarb,
has
been
reported
to
be
transformed
by
chlorination
during
35
water
purification
(
Magara
et
al.,
1994).
The
chlorine
reaction
with
the
pesticide
present
in
raw
water
can
be
described
as:

Thiobencarb
YYYY
Chlorobenzyl
Alcohol
+
Chlorotoluene
+
Chlorobenzoic
Acids
+
Chlorobenzyl
Chloride
+
Chlorobenzyl
Aldehyde
It
was
further
reported
that
when
thiobencarb
was
detected
in
raw
water,
chlorobenzyl
chloride
(
up
to
12
µ
g/
L),
chlorobenzoic
acid,
and
chlorobenzaldehyde
were
detected
in
the
filter
water
of
a
Japanese
purification
plant
for
water
supply.

3.8(
b)
2
Ozonation
Byproducts
Ozone
is
a
powerful
oxidizing
agent
that
can
react
in
water
directly
with
dissolved
organic
compounds
or
generate
radical
species
such
as
a
hydroxy
radical
(
OHC)
which
is
much
more
reactive.
Experiments
were
conducted
by
Adams
and
Randtke
(
1992)
on
the
ozonation
of
atrazine
in
natural
and
synthetic
waters
with
a
maximum
initial
concentration
of
15
ug/
L.
Two
conditions
were
used:
(
a)
low
pH
and
high
alkalinity,
which
inhibited
the
autodecomposition
of
ozone
to
the
hydroxy
radical;
(
b)
high
pH
and
low
alkalinity,
which
favored
the
production
of
hydroxy
radical
from
ozone.
The
natural
waters
were
obtained
from
Clinton
Reservoir,
Perry
Reservoir,
Kansas
River
and
Missouri
River.
The
investigators
proposed
the
following
major
degradation
pathway
for
the
ozonation
of
atrazine
in
water
treatment
processes:

atrazine
v
deethylatrazine
+
deisopropylatrazine
+
deisopropylatrazine
amide
+
2­
chloro­
4,6­
diamino­
s­
triazine
The
other
minor
pathway
described
yielded
byproducts
such
as
hydroxyatrazine,
2­
amino­
4­
ethylamino­
6­
hydroxy­
s­
triazine,
and
2­
amino­
4­
hydroxy­
6­
ethylamino­
s­
triazine.

The
kinetic
formation
trends
of
the
products
were
observed
to
change
as
pH
increased
from
5
to
7,
and
then
9.
Other
additional
products
formed
by
atrazine
reaction
with
ozone
with
or
without
hydrogen
peroxide
were
recently
reported
by
other
investigators
(
Acero
et
al,
2000;
Nelieu
et
al,
2000).

Due
to
a
growing
interest
in
removal
and
transformation
of
pollutants
during
ozonation,
attempts
have
been
made
to
evaluate
the
reactivity
of
pesticides
with
ozone
in
water.
Hu
et
al
(
2000)
determined
the
rate
constant
of
ozone
with
4
groups
of
pesticides
(
4
phenolic­,
8
organonitrogen­,
8
phenoxyalkylacetic
acid­,
and
4
heterocyclic
 
pesticides)
under
controlled
conditions
simulating
natural
waters.
The
results
of
the
correlation
analysis
indicated
that
the
reactivity
of
pesticides
can
be
estimated
using
the
energy
of
the
highest
occupied
molecular
orbital
of
the
chemicals
(
 HOMO
).
A
pesticide
with
a
high
 HOMO
can
be
expected
to
yield
a
high
rate
constant
of
ozonation.

36
Information
on
the
chemical
identities
and
concentrations
of
transformation
products
resulting
from
chemical
disinfection
is
important
in
drinking
water
exposure
assessment.
Rules
pertaining
to
allowable
levels
of
disinfection
by­
products
have
been
addressed
already
in
Europe
and
the
United
States.
The
European
Union
(
EU)
promulgated
a
new
regulation
that
establishes
not
only
maximum
concentrations
of
pesticides
in
drinking
water
but
also
includes
their
degradation
products
after
water
treatment
(
Acero
et
al,
2000).
In
the
United
States,
MCLGs
and
MCLs
also
have
been
developed
by
USEPA
for
several
by­
products
(
trihalomethanes,
haloacetonitriles,
haloketones,
haloacetic
acids,
etc.)
generated
from
chlorination
of
dissolved
organic
compounds
in
raw
water
under
the
D/
DBP.

3.9
Assessment
of
the
Relationship
Between
Environmental
Fate
Properties
and
Water
Treatment
Effects
As
part
of
the
pesticide
registration
process,
environmental
fate
and
transport
data
and
physicochemical
properties
for
each
pesticide
and
its
toxicologically
significant
degradation
products
are
required
to
assess
the
environmental
behavior
of
the
pesticide
under
specific
use
conditions
and
use
patterns.
The
core
environmental
fate
data
for
most
pesticide
registrations
are:
laboratory
studies
(
including
abiotic
hydrolysis,
photodegradation
in
water
and
soil,
aerobic
and
anaerobic
metabolism
in
water
and
soil,
batch
equilibrium/
soil
column
leaching,
volatility
from
soil,
bioaccumulation
in
fish)
and
physicochemical
properties
(
including
chemical
structure,
molecular
weight,
solubility,
vapor
pressure,
Henry s
Law
Constant,
octanol­
water
partitioning
coefficient,
and
dissociation
constants).
These
data
are
used
in
environmental
fate
models
for
estimating
pesticide
concentrations
in
aquatic
environments
and
drinking
water.
The
range
of
pesticide
properties
evaluated
in
referenced
water
treatment
studies
is
shown
in
Table
3.13.

An
analysis
was
conducted
to
assess
possible
relationships
between
pesticide
fate
properties
and
removal
efficiencies
for
GAC,
PAC,
and
RO.
Based
on
reviewed
data,
there
were
no
relationships
or
trends
observed
between
certain
pesticide
environmental
fate
properties
(
Kow
and
molecular
weight)
and
removal
efficiencies.
A
major
problem
with
the
analysis
is
associated
with
the
close
range
of
values,
which
limits
defining
trends
or
relationships.
Additional
data
are
needed
to
assess
trends
and
develop
regression
models
for
predicting
pesticide
removal
from
environmental
fate
and
physicochemical
data.

Qualitative
water
treatment
effects,
however,
may
be
predicted
using
environmental
fate
data.
For
example,
alkaline
catalyzed
hydrolysis
is
expected
to
occur
through
water
softening
because
of
the
pH
alteration
required
for
CaCO3
and
Mg(
OH)
2
precipitation.
This
effect
has
been
observed
for
carbofuran
because
it
hydrolyzes
rapidly
at
pH
9
(
Table
3.13).
Also,
pesticide
removal
through
adsorption
on
activated
carbon
can
be
predicted
using
physicochemical
properties.
Compounds
exhibiting
high
Koc,
low
solubility,
and
high
octanol­
water
partitioning
coefficients
are
expected
to
exhibit
high
binding
affinities
for
activated
carbon
(
Speth
and
Adams,
1993).
Further
oxidizability
of
the
pesticide
may
be
inferred
from
aerobic
soil
metabolism
data.
Compounds
with
short
aerobic
soil
metabolism
half­
lives
are
expected
to
be
more
prone
to
chemical
oxidation.
Finally,
functional
group
analysis
as
indicated
by
acid
or
base
dissociation
constants
provides
some
basic
information
on
speciation
of
the
pesticide
and
its
possible
adsorption
potential
(
cation
or
anion
exchange)
on
surfaces
of
colloids,
flocs,
and
activated
37
carbon.
Further
research
is
needed
in
assessing
the
quantitative
relationship
between
pesticide
fate
properties
and
removal
efficiencies.

38
Table
3.13.
Physicochemical
and
Environmental
Fate
Properties
of
Pesticides1
MW
pKa
or
pKb
log
kow
Koc
Henry's
Law
Constant
[
atm­
m3/
mol]
Vapor
Pressure
[
torr]
solubilty
[
ppm]
pH
7
hydrolysis
half
life
[
day]
pH
9
hydrolysis
half
life
[
day]
aqueous
photolysis
half
life
[
day]
aerobic
soil
metabolism
half
life:
typical
and
(
range)
[
day]

2,4,5­
T
255.48
2.84
a
3
238
alachlor
269.77
2.64
190
3.20E­
08
2.2
E­
05
242
stable
stable
80
17.5
(
14­
21)

aldicarb
190.26
0.7
30
1.0
E­
04
6000
stable
16.7
(
1­
56)

aldrin
364.91
3.01
7.5
E­
05
0.027
atrazine
215.69
12.3
2.68
88
2.58E­
09
3.0
E­
07
33
stable
stable
stable
83.5
(
21­
146)

bentazon
240.3
21
6.30E­
12
1.0
E­
09
500
stable
stable
<
1
38.6
(
14­
65)

captan
300.59
8.0
E­
08
33
0.25
0.005556
stable
4
(
1­
7)

carbofuran
221.6
1.98
29
5.2
E­
07
700
7.28
0.625
stable
130
(
21­
350)

chlordane
409.78
3.32
1.4E5
9.60E­
06
1.0
E­
05
600
cyanazine
240.7
12.9
56
3.17E­
12
1.00E­
08
171
stable
stable
43
28.5
(
10­
70)

DBCP
236.36
2.78E­
03
10
1000
180
diazinon
304.34
3.01
530
1.40E­
06
1.4
E­
04
40
stable
stable
34
18
(
4­
28)

dichloropropene
110.97
36
1.80E­
03
27.3
2500
13.5
13.5
33
(
12­
54)

dieldrin
380.91
8.08E­
03
3.1
E­
06
0.25
diuron
233.1
2.81
480
2.26E­
08
8.6
E­
09
42
stable
stable
43
98
(
30­
144)

endrin
380.91
4.00E­
07
2.0
E­
07
ethylene
dibromide
187.85
1.76
22.5
6.73E­
04
11.7
4300
heptachlor
373.32
4.41
4.00E­
03
3.0
E­
04
0.06
64
(
37­
112)

heptachlor
epoxide
389.3
2.7
220
4.00E­
04
3.0
E­
04
0.35
lindane
290.83
1263
3.60E­
07
9.4
E­
06
10
stable
36
stable
523
(
66­
980)

linuron
249.1
2.19
863
6.56E­
08
1.1
E­
05
75
stable
stable
49­
76
87.5
(
84­
91)

methoxychlor
345.65
3.62
8E5
0.1
stable
stable
stable
120
metolachlor
283.8
229
9.16E­
09
1.3
E­
05
530
stable
stable
70
67
metribuzin
214.29
13
1.6
19
3.50E­
11
1.2
E­
07
1100
stable
stable
0.179167
73
(
40­
106)

parathion
291.26
1.8E4
3.8
E­
05
24
108
95
(
50­
140)

pendimethalin
281.31
3.6E4
2.22E­
05
2.9
E­
06
0.38
stable
stable
17­
21
1322
simazine
201.66
12.35
2.51
124
3.20E­
10
6.1
E­
09
3.5
stable
stable
stable
36
toxaphene
413.81
1E5
0.17
0.037
9
trifluran
335.28
5.07
8000
1.62E­
04
1.1
E­
04
0.3
stable
stable
0.37
115
1­
Data
were
derived
from
the
EFED
One­
Liner
Data
Base.

MW
=
Molecular
Weight
pKa
=
negative
log
of
acid
dissociation
constant
pKb
=
negative
log
of
base
dissociation
constant
Kow
=
octanol/
water
partition
constant
Koc
=
organic
carbon
sorption
coefficient
39
40
3.10
Acknowledgments
Technical
quality
assurance
of
the
water
treatment
section
was
evaluated
using
internal
peer
reviewers
from
the
EPA/
Office
of
Pesticide
Programs
Water
Quality
and
Aquatic
Exposure
Technical
Team
(
Dr.
Jim
Cowles,
Dr.
R.
David
Jones,
Dr.
Lawrence
Libelo,
and
Mr.
Nelson
Thurman,
Mr.
Sid
Abel,
Ms.
Stephanie
Syslo,
and
Mr.
James
Breithaupt),
EPA/
Office
of
Ground
Water
and
Drinking
Water
(
Mr.
Jeff
Kempic)
and
EPA/
Office
of
Research
and
Development
(
Dr.
Thomas
Speth).
External
technical
reviewers
include
American
Water
Work
Association,
and
American
Crop
Protection
Association.

3.11
Literature
Cited
Abel,
S.
1992.
Drinking
water
Treatment
Processes
and
Treatment
Efficiencies
for
Organic
Contaminants:
Utilities
Using
Surface
Water
Sources.
Sept.
10,
1992
Deliverable
1
for
Task
No.
3­
44
under
Contract
No.
68­
D9­
0166
from
Versar,
Inc.,
6850
Versar
Center,
P.
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Springfield,
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1992.
Removal
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Behavior
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J.
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February,
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D.
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Treatment
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81:
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C.
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Removal
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R.
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1998).

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1989.
Relationship
between
Toxicity
and
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of
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and
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Larvae
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United
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T.
F.
and
J.
Q.
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GAC
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Stripping
Design
Support
for
the
Safe
Drinking
Water
Act ,
Strategies
and
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T.
F.
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J.
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1998.
Technical
note:
adsorption
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Jour.
AWWA.
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43
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1997.
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001b.

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1989.
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1998.
Small
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98­
002.

van
Rensburg,
J.
F.
J.,
P.
G.
van
Rossum,
and
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H.
J.
Hattingh.
1978.
The
Occurrence
and
Fate
of
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in
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Tech.
10(
1&
2):
41­
48.

44
APPENDIX
A.
REMOVAL
OF
PESTICIDES
USING
DIFFERENT
REVERSE
OSMOSIS
MEMBRANES
Class/
Pesticide
Membrane
Co
(
µ
g/
L)
%
Removal
Reference
Triazine
Atrazine
Cellulose
Acetate
86.5
­
161.3
(
GW)
2.46
­
11.75
(
SW)
38.5
29
Fronk
&
Baker
(
1990)
Fronk
&
Baker
(
1990)

Polyamide
86.5
­
161.3
(
GW)
2.46
­
11.75
(
SW)
68
78
Fronk
&
Baker
(
1990)
Fronk
&
Baker
(
1990)

Thin
Film
Composite
(
FT­
30)
2.46
­
11.75
(
SW)
100
Fronk
&
Baker
(
1990)

Thin
Film
Composite
(
DSI)
86.5
­
161.3
(
GW)
80­
100
Fronk
&
Baker
(
1990)

CA
1101.7
97.82
Eisenberg
&
Middlebrooks
(
1986)

NS­
100
1101.7
84.02
Eisenberg
&
Middlebrooks
(
1986)

Cyanazine
Cellulose
Acetate
0.0
­
2.53
(
SW)
40­
50
Fronk
&
Baker
(
1990)

Polyamide
0.0
­
2.53
(
SW)
69
Fronk
&
Baker
(
1990)

Thin
Film
Composite
(
FT­
30)
0.0
­
2.53
(
SW)
100
Fronk
&
Baker
(
1990)

Metribuzin
Cellulose
Acetate
0.0
­
2.53
(
SW)
59
Fronk
&
Baker
(
1990)

Polyamide
0.0
­
2.53
(
SW)
76
Fronk
&
Baker
(
1990)

Thin
Film
Composite
(
FT­
30)
0.0
­
2.53
(
SW)
100
Fronk
&
Baker
(
1990)

Simazine
Cellulose
Acetate
86.1
­
117.2
(
GW)
0.11
­
0.82
(
SW)
31
23
Fronk
&
Baker
(
1990)
Fronk
&
Baker
(
1990)

Polyamide
86.1
­
117.2
(
GW)
0.11
­
0.82
(
SW)
85
72
Fronk
&
Baker
(
1990)
Fronk
&
Baker
(
1990)

Thin
Film
Composite
(
FT­
30)
0.11
­
0.82
(
SW)
100
Fronk
&
Baker
(
1990)

45
Class/
Pesticide
Membrane
Co
(
µ
g/
L)
%
Removal
Reference
Thin
Film
Composite
(
DSI)
86.1
­
117.2
(
GW)
99
Fronk
&
Baker
(
1990)

Acetanilide
Alachlor
Cellulose
Acetate
0.78
­
6.44
(
SW)
70
Fronk
&
Baker
(
1990)

Polyamide
0.78
­
6.44
(
SW)
77
Fronk
&
Baker
(
1990)

Thin
Film
Composite
(
FT­
30)
73.4
­
106
(
GW)
0.78
­
6.44
(
SW)
100
100
Fronk
&
Baker
(
1990)
Fronk
&
Baker
(
1990)

Cellulose
Acetate
1.65
(
SW)
71.4
Miltner
et.
al.(
1989)

Nylon
Amide
1.65
(
SW)
84.6
Miltner
et.
al.(
1989)

Thin
Film
Composite
1.65
(
SW)
98.5
Miltner
et.
al.(
1989)

Metolachlor
Cellulose
Acetate
2.73
­
14.61
(
SW)
80
Fronk
&
Baker
(
1990)

Polyamide
2.73
­
14.61
(
SW)
78
Fronk
&
Baker
(
1990)

Thin
Film
Composite
(
FT­
30)
30.9
­
111
(
GW)
2.73
­
14.61
(
SW)
100
100
Fronk
&
Baker
(
1990)
Frank
&
Baker
(
1990)

Urea
Derivative
Linuron
Cellulose
Acetate
74.7
­
106.8
(
GW)
0.0
­
1.18
(
SW)
0
0
Fronk
&
Baker
(
1990)
Fronk
&
Baker
(
1990)

Polyamide
74.7
­
106.8
(
GW)
0.0
­
1.18
(
SW)
57
100
Fronk
&
Baker
(
1990)
Fronk
&
Baker
(
1990)

Thin
Film
Composite
(
FT­
30)
0.0
­
1.18
(
SW)
100
Fronk
&
Baker
(
1990)

Thin
Film
Composite
(
DSI)
74.7
­
106.8
(
GW)
99
Fronk
&
Baker
(
1990)

Organo­
chlorine
Aldrin
CA
142.3
100
Eisenberg
&
Middlebrooks
(
1986)

46
Class/
Pesticide
Membrane
Co
(
µ
g/
L)
%
Removal
Reference
NS­
100
142.3
100
Eisenberg
&
Middlebrooks
(
1986)

Heptachlor
CA
505.4
100
Eisenberg
&
Middlebrooks
(
1986)

NS­
100
505.4
100
Eisenberg
&
Middlebrooks
(
1986)

Dieldrin
CA
321.3
99.88
Eisenberg
&
Middlebrooks
(
1986)

NS­
100
321.3
100
Eisenberg
&
Middlebrooks
(
1986)

Organophosphate
Diazinon
CA
437.7
98.25
Eisenberg
&
Middlebrooks
(
1986)

NS­
100
437.7
98.05
Eisenberg
&
Middlebrooks
(
1986)

Malathion
CA
1057.8
99.16
Eisenberg
&
Middlebrooks
(
1986)

NS­
100
1057.8
99.66
Eisenberg
&
Middlebrooks
(
1986)

Parathion
CA
747.3
99.88
Eisenberg
&
Middlebrooks
(
1986)

NS­
100
747.3
99.83
Eisenberg
&
Middlebrooks
(
1986)

Others
Captan
CA
668.9
97.78
Eisenberg
&
Middlebrooks
(
1986)

NS­
100
668.9
100
Eisenberg
&
Middlebrooks
(
1986)

Trifluralin
CA
1578.9
99.74
Eisenberg
&
Middlebrooks
(
1986)

NS­
100
1578.9
99.99
Eisenberg
&
Middlebrooks
(
1986)

Carbofuran
Cellulose
Acetate
14
(
GW)
85.7
Lykins
et
al(
1988);
Fronk
et
al
(
1990)

Polyamide
14
(
GW)
>
92.9
Lykins
et
al(
1988);
Fronk
et
al
(
1990)

47
Class/
Pesticide
Membrane
Co
(
µ
g/
L)
%
Removal
Reference
Thin
Film
Composite*
14
(
GW)
>
92.9
Lykins
et
al(
1988);
Fronk
et
al
(
1990)

Polyamide**
4.3
­
9.8
(
GW)
79.6
­
90.0
Lykins
et
al(
1988);
Fronk
et
al
(
1990)

1,2­
Dichloro­
propane
Cellulose
Acetate
24
(
GW)
4.2
Lykins
et
al(
1988);
Fronk
et
al
(
1990)

Polyamide
24
(
GW)
75
Lykins
et
al(
1988);
Fronk
et
al
(
1990)

Thin
Film
Composite*
24
(
GW)
37.5
­
87.5
Lykins
et
al(
1988);
Fronk
et
al
(
1990)

Polyamide**
17.5
­
22.2
(
GW)
52.6
­
71.2
Lykins
et
al(
1988);
Fronk
et
al
(
1990)

Aldicarb
Sulfoxide
Cellulose
Acetate
39
(
GW)
>
97.4
Lykins
et
al(
1988);
Fronk
et
al
(
1990)

Polyamide
39
(
GW)
>
97.4
Lykins
et
al(
1988);
Fronk
et
al
(
1990)

Thin
Film
Composite*
39
(
GW)
94.9
­
97.4
Lykins
et
al(
1988);
Fronk
et
al
(
1990)

Polyamide**
11.2
­
20.0
(
GW)
91.1
­
95.0
Lykins
et
al(
1988);
Fronk
et
al
(
1990)

Aldicarb
Sulfone
Cellulose
Acetate
47
(
GW)
93.6
Lykins
et
al(
1988);
Fronk
et
al
(
1990)

Polyamide
47
(
GW)
95.7
Lykins
et
al(
1988);
Fronk
et
al
(
1990)

Thin
Film
Composite*
47
(
GW)
93.6
­
95.8
Lykins
et
al(
1988);
Fronk
et
al
(
1990)

Polyamide
14.0
­
31.4
(
GW)
91.4
­
95.8
Lykins
et
al(
1988);
Fronk
et
al
(
1990)
*
Bench
scale
studies
using
spiked
groundwater
from
Suffolk
County,
NY
**
Pilot
plant
studies
in
Suffolk
County,
NY
48
Appendix
B.
Questions
for
Public
Comment
1
Do
the
scientific
data
demonstrate
clear
quantitative
relationships
exist
between
the
physical/
chemical
properties
of
particular
pesticide
classes
and
specific
water
treatments
processes?

2.
Based
on
its
technical
review
of
the
literature
on
the
impacts
of
different
treatment
processes
on
levels
of
pesticide
residues
in
drinking
water,
OPP
is
leaning
toward
an
interim
approach
which
assumes,
in
the
absence
of
representative
pesticide­
specific
water
plant
monitoring
data,
that
residues
in
finished
drinking
water
will
be
the
same
as
levels
in
such
water
prior
to
treatment.
Given
the
objective
of
accurately
estimating
pesticide
concentrations
in
drinking
water,
do
the
scientific
data
support
this
approach?
How
would
an
approach
be
developed
based
on
the
state
of
knowledge
about
the
impact
of
treatment
on
pesticides?
Under
what
circumstances
can
OPP
use
data
on
the
impacts
of
a
specific
treatment
process
on
several
pesticides
in
a
chemical
class
to
support
a
general
conclusion
about
all
pesticide
in
that
class?

3
During
disinfection
with
chlorine,
pesticides
such
as
organophosphates
can
be
oxidized
to
form
toxic
degradation
products.
What
other
classes
of
pesticides
may
be
transformed
by
drinking
water
treatment
processes
to
form
toxic
byproducts?
What
issues
related
to
pesticide
transformation
should
OPP
be
aware
of?

4
Laboratory
jar
tests
are
often
employed
to
determine
if
a
regulated
contaminant,
including
some
pesticides,
in
raw
water
can
be
removed
by
a
given
treatment
process.
What
are
the
advantages
and
disadvantages
of
using
results
of
jar
tests
as
the
basis
of
evaluating
whether
the
pesticide
will
be
eventually
removed
in
the
actual
water
treatment
plant?
How
might
these
results
be
used
to
adjust
raw
water
concentrations
for
use
in
human
health
risk
assessment?
What
are
the
advantages
and
disadvantages
of
using
other
types
of
data,
e.
g.
paired
samples
from
field
monitoring,
or
pilot
plant
data.

5
Studies
cited
in
the
literature
review
indicate
that
many
factors,
such
as
raw
water
composition,
water
treatment
method,
and
treatment
plant
conditions,
may
affect
the
removal
of
pesticides.
What
issues
should
OPP
be
considering
in
determining
the
potential
impact
of
these
factors
on
the
percent
removal
and
transformation
of
pesticides
by
different
water
treatment
plants?

6
What
additional
water
treatment
data
from
other
studies,
which
either
support
or
are
inconsistent
or
contradict
the
data
presented
in
the
preliminary
literature
review,
should
OPP
consider?
Please
submit
any
data
that
would
provide
information
on
the
impacts
of
water
treatment
on
additional
pesticides
or
classes
of
pesticides.

7.
For
example,
some
pesticides,
including
carbamates
and
organophosphates,
with
hydrolysis
half­
lives
of
less
than
1
day
in
alkaline
(
pH
9)
water
are
observed
to
be
 
removed 
during
lime­
soda
softening
(
pH
10~
11)
by
alkaline
hydrolysis.
Can
this
observation
be
generalized
in
predicting
whether
a
pesticide
with
alkaline
abiotic
49
hydrolysis
half­
life
of
less
than
1
day
will
be
 
removed 
through
water
treatment?

8
The
effects
of
water
treatment
on
pesticide
residues
in
drinking
water
can
be
assessed
by
regression
modeling
of
important
parameters
with
removal
efficiency,
experimental
or
laboratory
studies,
and
actual
field
monitoring.
What
other
approaches
or
methods
can
be
used
to
assess
water
treatment
effects?
What
are
the
pros
and
cons
of
these
methods?

9.
What
types
of
data
are
needed
regarding
the
extent
and
manner
of
use
of
a
particular
drinking
water
treatment
process
in
order
to
use
the
data
on
the
impact
of
such
method
on
pesticide
concentrations
in
finished
drinking
water
in
a
deterministic
or
probabilistic
exposure
assessment?

50