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MEMORANDUM
TO:
Carey
Johnson,
EPA
FROM:
Birute
Vanatta
and
Joy
Abel,
ERG
DATE:
March
30,
2004
SUBJECT:
Costs
for
a
Counter
Current
Ion
Exchange
System
(
Higgins
Loop)
to
Treat
Coalbed
Methane
Water
in
the
Powder
River
Basin
The
purpose
of
this
memorandum
is
to
describe
the
ion
exchange
technology
used
to
treat
coalbed
methane
(
CBM)
water
and
the
methodology
used
to
estimate
the
engineering
costs
for
implementing
the
ion
exchange
treatment.

Ion
Exchange
Technology
The
Higgins
Loop
ion
exchange
system
uses
cation
and
anion
resins
to
remove
sodium,
chloride,
sulfate,
and
other
ions
from
CBM
water.
The
CBM
water
must
be
degassed
of
methane
prior
to
entering
the
system
facility
for
personal
safety
reasons.
This
can
be
accomplished
using
a
gas
separator
or
a
small
receiving
pit.
The
CBM
water
enters
a
small
influent
tank
used
as
a
feed
tank
to
the
system.
Once
the
water
enters
the
system,
it
moves
through
the
adsorption
zone,
where
a
strong
acid
cation
exchange
resin
(
Dow
G­
26
resin)
is
used
to
remove
the
cations
from
CBM
water.
The
cations
in
the
CBM
water
are
replaced
by
hydronium
ions
from
the
resin
beads.
This
lowers
the
pH
level
of
the
CBM
water
and
bicarbonate
ions
begin
to
react
with
the
hydronium
ions
to
form
carbon
dioxide
gas.
The
treated
water
is
then
discharged
to
a
neutralizing
bed
where
the
excess
hydronium
ions
and
residual
bicarbonate
ions
(
or
carbon
dioxide
gas
in
solution,
depending
the
pH)
can
react
with
selected
calcium
minerals
to
achieve
the
desired
final
pH.
The
selection
of
the
neutralizing
agent
varies
with
the
desired
final
pH
and
the
intended
use
of
the
treated
water.
Typically,
limestone
is
used
as
the
neutralizing
agent.

As
the
CBM
water
is
being
treated,
cations
are
removed
from
the
resin
in
the
regeneration
section
of
the
system.
Hydrochloric
or
sulfuric
acid
is
injected
into
the
system,
which
moves
countercurrent
to
the
resin.
This
regeneration
process
restores
the
resin
to
its
hydronium
form.
The
hydrochloric
acid
is
transported
to
the
treatment
facility
and
stored
in
poly
tanks
designed
for
hydrochloric
acid
containment
and
have
a
vapor
scrubber
in
line.
A
chemical
feed
pump
is
used
to
pump
the
hydrochloric
acid
into
the
ion
exchange
system.
Once
the
acid
enters
the
system,
it
is
diluted
down
to
14
percent
and
introduced
directly
into
the
regeneration
Memorandum
30
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2004
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phase
of
the
system.
The
regenerated
resin
is
rinsed
with
water
to
remove
any
residual
acid
before
reentering
the
adsorption
zone.
This
process
generates
a
concentrated
brine,
which
is
removed
for
disposal.

The
concentrated
brine
volumes
range
from
0.8
percent
to
2
percent
of
the
influent
CBM
water
volume,
depending
on
the
cation
loading
that
is
removed
from
the
treated
water.
The
concentrated
brine
is
typically
stored
on
site
until
there
is
enough
for
a
truck
load.
Then,
it
is
transported
to
a
commercial
disposal
facility,
where
it
is
disposed
using
an
injection
well.

If
the
upper
layer
of
the
adsorption
zone
becomes
loaded
with
sodium,
the
ion
exchange
system
is
designed
to
interrupt
the
flow
to
the
system
to
allow
the
resin
to
pulse
in
the
opposite
direction
of
the
water
flow.
Once
the
resin
pulsing
is
completed,
the
water
flow
into
the
system
is
restarted.
In
addition,
the
system
is
designed
to
backwash
any
solids
out
of
the
resin.
The
solids
and
small
amounts
of
resin
are
backwashed
into
the
resin
recovery
tank.
Periodically,
the
operator
will
remove
the
resin
from
this
tank
and
add
it
back
into
the
system.
If
silts
accumulate
in
the
resin
recovery
tank,
the
operator
removes
them.

This
system
is
effective
at
reducing
total
dissolved
solids
(
TDS)
levels
of
1,600
to
1,800
milligrams
per
liter
(
mg/
L)
to
below
500
mg/
L.
The
limitations
of
the
system
are
determined
by
the
total
cation
load
of
the
CBM
water.
The
system
is
designed
for
total
cation
loads
with
a
sodium
equivalent
of
500
mg/
L.
The
life
span
of
the
ion
exchange
system
is
typically
15
to
20
years.
The
system
is
capable
of
treating
CBM
water
with
13
percent
solids,
therefore,
pretreatment
is
not
required.

The
Higgins
Loop
has
been
a
viable
system
for
many
years
and
has
a
history
of
97
percent
or
greater
up
time
or
continuous
runtime.
The
design
of
the
system
allows
for
most
of
the
required
maintenance
(
e.
g.,
replacement
of
small
control
valves)
to
be
replaced
during
operation.
Most
of
the
down
time
that
has
been
experienced
is
related
to
temperature
generator
power
failure.

Ion
Exchange
Costs
Costs
were
calculated
for
each
of
the
model
projects
in
the
economic
model
used
for
the
draft
Guidance
for
Developing
Technology­
Based
Limits
for
Coalbed
Methane
Operations:
Economic
Analysis
of
the
Powder
River
Basin.
Costs
in
dollars
per
barrel
were
obtained
from
Terry
Olson
at
EMIT
Water
Discharge
Technology,
LLC
(
EMIT).
EMIT
is
the
vendor
pursuing
this
treatment
option
in
the
Powder
River
Basin.
The
total
cost
per
barrel
was
provided
for
different
sodium
adsorption
ratio
(
SAR),
sodium,
and
TDS
levels.
In
addition,
the
costs
for
two
different
ion
exchange
models
were
provided.
See
Attachment
A
for
the
costs
provided
by
the
vendor.
The
information
presented
in
Attachment
A
was
used
to
assign
costs
to
Memorandum
30
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the
model
projects.
The
vendor
builds,
operates,
and
maintains
these
systems
and
charges
the
owner
of
the
CBM
operation
a
fixed
amount
per
barrel
of
CBM
water
treated.
The
fixed
cost
per
barrel
of
CBM
water
treated
includes
the
equipment,
O&
M,
chemicals,
a
SCADA
system
for
remote
control
and
monitoring,
and
disposal
of
any
waste
streams
generated.
The
vendor
also
provided
a
breakdown
of
the
total
costs
(
see
Attachment
B).
These
costs
were
designated
as
either
operating
and
maintenance
(
O&
M)
or
capital
costs,
as
follows:

O&
M
costs:


Maintenance
supplies

pH
control

Resin
usage

Operations/
maintenance

Waste
stream
disposal

Electric
power

Regeneration
fluid
­
HCL
Capital
Costs:


Capital
recoup

SCADA
system
The
percentage
of
the
total
costs
associated
with
O&
M
is
78.6
percent.
The
percentage
of
the
total
costs
associated
with
capital
expenditures
is
21.4
percent.
The
total
costs
per
barrel
were
multiplied
by
these
percentages
to
calculate
the
cost
per
barrel
associated
with
O&
M
and
capital
expenditures.
Attachment
C
presents
the
O&
M
and
capital
costs
for
each
model
project.

The
costs
for
this
ion
exchange
system
are
based
mainly
on
the
cation
loads
in
the
CBM
water.
Therefore,
the
system
does
have
limitations
on
the
cation
levels
that
can
be
treated
before
it
becomes
uneconomical.
Typically,
when
the
cation
levels
exceed
1,500
mg/
L,
the
system
will
become
uneconomical.
As
the
sodium
levels
increase,
three
main
factors
effect
the
cost
of
the
system:

1.
The
contact
time
required
increases
resulting
in
a
reduction
in
the
volume
of
CBM
water
that
can
be
treated.
2.
More
hydrochloric
acid
is
consumed
in
the
regeneration
phase.
3.
The
volume
of
concentrated
brine
increases.

The
following
table
presents
additional
information
regarding
the
O&
M
costs
associated
with
the
ion
exchange
system.
Memorandum
30
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Table
1.
Description
of
O&
M
Costs
Parameter/
Cost
Description
Value
Land
required
Land
required
is
dependent
on
the
volume
of
water
to
be
treated.
One
unit
typically
requires
½
of
an
acre.
Multiple
units
may
require
two
to
three
acres.
$
1000
per
acre
per
year
Disposal
of
brine
The
cost
for
disposal
at
a
commercial
disposal
facility
varies.
The
cost
of
disposal
is
less
than
$
1.00
per
barrel
of
brine.
The
transportation
cost
will
vary
depending
on
the
proximity
to
the
disposal
facility.
$
4.40
per
barrel
of
brine
(
average)

Labor
hours
One
man
can
operate
up
to
five
units
in
an
8
hour
day
under
normal
circumstances.
The
SCADA
system
is
monitored
constantly
throughout
the
day
and
it
has
a
call­
out
feature
after
hours.
5
hours
per
day
per
unit
Labor
cost
Cost
of
man
hours
$
20.00
per
hour
Horsepower
required
Horsepower
required
to
operate
the
system
35
horsepower
(
Model
3012
)
80
horsepower
(
Model
6024)

Resin
replacement
Approximately
15
percent
of
the
resin
has
to
be
replaced
each
year.
Model
3012
has
a
resin
capacity
of
80
cubic
feet
and
Model
6024
holds
320
cubic
feet.
$
135
­
$
165
per
cubic
foot
Limestone
consumption
Limestone
is
used
as
a
neutralizing
agent.
The
neutralization
phase
requires
very
little
up
front
capital
and
maintenance.
$
0.001
per
barrel
Hydrochloric
acid
Costs
vary
based
on
the
trucking
distance
or
time.
The
chemical
supplier
transports
the
hydrochloric
acid
via
rail
and
then
it
is
transported
to
the
facility.
$
115
per
ton
for
22

Baume
or
36%
HCl
The
cost
of
the
ion
exchange
system
can
be
reduced
proportionately
with
blending
treated
water
with
untreated
CBM
water
to
achieve
the
desired
effluent
quality.
In
addition,
it
should
be
noted
that
the
vendor
has
developed
two
models
for
treating
CBM
water.
Model
3012
treats
smaller
volumes
of
CBM
water
(
approximately
4,800
to
69,000
barrels
per
day)
as
compared
to
Model
6024,
which
treats
higher
volumes
(
approximately
20,000
to
240,000
barrels
per
day)
at
the
same
influent
levels.
The
model
projects
used
in
this
analysis
had
small
enough
volumes
of
water
that
only
the
costs
for
Model
3012
were
used.
However,
if
more
wells
were
combined
and
the
volume
increased
so
that
Model
6024
could
be
used,
the
cost
per
barrel
would
decrease.
The
costs
are
13
to
30
percent
less
per
barrel
using
Model
6024,
depending
on
the
influent
water
quality
and
the
desired
effluent
quality.
Memorandum
30
March
2004
Page
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Attachment
A
C:\
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Attachment
B
C:\
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Attachment
C
