United States
Environmental Protection
Agency
Hazardous Waste Engineering
Research Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S2-87/072 Nov. 1987
SERA Project Summary
A Field Dispersant Effectiveness
Test
Anibal Diaz
The EPA's Releases Control Branch
of the Hazardous Waste Engineering Re-
search Laboratory has developed a rapid
field test to evaluate the dispersibility
of various commonly-transported oils
to provide a data base for dispersant
selection and application.
The Field Dispersant Effectiveness
Test (FDET) is designed to generate
droplet sizes that closely resemble the
dispersion of oil occurring at sea. A
fixed mixing intensity and time induces
the effects necessary to produce the
dispersion and reveal the effectiveness
of the dispersant and dispersibility of
the oil.
This Project Summary was developed
by EPA's Hazardous Waste Engineering
Research Laboratory, Cincinnati, OH, to
announce key findings of the research
report that Is fully documented In a
separate report of the same title (see
Project Report ordering Information at
back).
Introduction
This project was conducted to develop
a Field Dispersant Effectiveness Test
(FDET) and determine the dispersibility of
various commonly transported oils (mostly
crude). The test is required to be economi-
cal, simple enough for use in the field,
and able to provide realistic results. In
addition, the test was used to generate a
data base that has much of the informa-
tion necessary to determine the feasibility
of dispersing a specific spilled oil and the
chemical agent(s) best suited for the job.
Initial steps in this study included
evaluating the theoretical implications of
shaking a sealed container to generate
the desired oil droplets. The primary con-
straint was to make the droplets small
enough (i.e., 10-20 /im) to approach the
values encountered with ocean induced
dispersion. Various methods were con-
sidered for the mixing process and
demonstrated that moving the mixture of
oil, dispersant and water in a sealed tube
along its longitudinal axis at a set fre-
quency, stroke length and time would
provide the necessary energy level to
produce an acceptable dispersion.
The practical constraints of time saving
and simplicity were met by utilizing an
apparatus that was readily available from
any hardware store or laboratory (see
Figure 1). A standard half-inch test tube
was used for mixing the dispersant, oil
and water, and a flashlight, ruler, and
stopwatch, for determining the separation
of the oil from the water. The height of
the clear water space under the dispersed
oil layer provided the basis for calculating
the Percent Dispersion. The entire test
procedure requires less than fifteen
minutes.
Finally, the FDET was used to evaluate
various oils and dispersants and to
develop a data base of oil dispersibility.
Eighteen commonly transported crude oils
and six dispersants were selected for the
test (see Table 1). Nine of the oils were
also sparged and six were emulsified
with water to make them comparable to
the oil at a spill site. Three different
dispersant-to-oil ratios were used to
determine the best combination and each
test was performed in triplicate to meet
data quality objectives. The results were
put into a dBase III program for future
reference.
Description of the Technique
The FDET has been designed to produce
an oil dispersion that closely resembles
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the product of wave action at sea. The
turbulent flow theory was followed to
arrive at the mixing required. Various
manual methods were considered to
obtain the necessary small scale turbu-
lence. A 1/2-inch test tube to hold the
mixture and a regulated hand shake for
the mixing process proved successful.
The FDET relies on a specific mixing
pattern. The mixture of dispersant oil and
water is shaken in the stoppered test
tube. The oil disperses as the tube is
moved along the longitudinal axis at 120
cycles per minute with a 4-inch stroke
length for one minute. Stronger mixing
produces a smaller droplet size but fails
to provide greater resolution between a
good and a poor dispersion. Weaker
mixing fails to provide sufficient stability
to the dispersion.
The determination of percent dispersion
requires a measurement of the visible
water space in the tube after settling for
10 minutes. As expected, the oil droplets
rise out of the water column leaving a
clear space underneath a dark oil layer. A
good dispersion allows a slower separa-
tion rate and a smaller distance between
the tip of the tube and the opaque oil
dispersion in the given time while a poor
dispersion gives a faster separation rate
and a larger clear water space under the
oil dispersion in the same amount of
time. The difference between the clear
space, L, and the initial water height (i.e.,
5 cm) provides a measure of the amount
of oil dispersion left in the tube at that
point. The dispersibility or effectiveness
values are derived by substitution into
the equation:
Table 1. List of Test Fluids
D =
x100%
Where,
D = percent dispersed
5 = initial water height in test tube
L = height from tip of tube to opaque
layer
Procedures
Test Fluids
The oils and dispersants considered in
this study are listed in Table 1 . Each oil
was analyzed for various physical pro-
perties as a quality measure for future
comparative studies of their dispersibility.
Several samples were sparged with air
and heated on a steam bath or emulsified
with water to make them more similar to
the oils found at a spill site. The treatment
promotes the loss of the most volatile
components of the oils and changes their
viscosity, specific gravity and flash point.
Oils
Arabian Light
Prudhoe Bay
South Louisiana
No. 2 Fuel
Bunker C
Bunker C
Bachequero
Laqunillas
Mississippi Heavy
BCF-17
Topped Lago Medio
Minas Crude
Murban
La Rosa
Gabon
Hybernia
Amauligak
Alberta
DFM
Dispersants
D— 609
1100WD
1100X
Corexit9527
Magnotox
ECO Atlantol AT7
Source
API/EPA SROP
API/EPA SROP
API/ EPA SROP
API/EPA SROP
API/EPA SROP
API
API — Exxon
API — Exxon
API — Texaco
API — Texaco
API — Texaco
API — Texaco
OHMSETT stock
OHMSETT stock
OHMSETT stock
OHMSETT stock
OHMSETT stock
OHMSETT stock
OHMSETT stock
Source
Arco Chemical Co.
British Petroleum
British Petroleum
Exxon Chemical Co.
Magnus Maritec Int'l. Inc.
ASPRA, Inc.
These are the same changes that occur
in the field.
Synthetic seawater was used for the
tests to avoid the influence of variation in
seawater composition. The test water
was prepared by mixing salts with tap
water in accord with the instructions
given by ASTMD 1145-75.
Test Methods
The test procedure consists of four
preparatory steps and the eight major
steps illustrated in Figure 1.
The preparation for testing includes
filling a test tube to 5 cm with the
synthetic seawater, filling one dropper
with oil and another with dispersant and
custom fitting opaque shield over a flash-
light to direct the illumination through a
centrally located aperture.
The major steps include the shaking,
settling, and measurement of a water/oil
interface to determine the oil dispersion.
Ten drops of oil and one drop of dispersant
were mixed into the water in a stoppered
test tube. The preferred mixing pattern
involved moving the tube for 1 minute at
120 cpm with a 4-inch stroke length. The
mixture was allowed to settle for 10
minutes, set the tube over the hole in the
shield covering the beam of the flashlight
and adjust an 0-ring around the tube at
the point light no longer penetrates
through the mixture. The positioning of
the 0-ring indicates the highest point of
translucence. The determination of the
interface for clear oils may require lateral
illumination of the tube and gradually
moving the tips of two pens held in
parallel between the light and the tube to
the point that they fuse into one shadow.
Subsequently, we measure the height of
this interface, L, from the tip of the test
tube to the 0-ring and use that number
to calculate the Percent Dispersion, D.
Results and Conclusions
It is possible to obtain a rapid evaluation
of oil dispersibility, at the site of an oil
spill, using readily available hardware
from the laboratory and proper application
of dispersants. A person responding to
an oil spill would only need a copy of the
FDET method, some dispersant, a couple
of droppers, a ruler, and a test tube to
determine the dispersibility of the oil. The
test could be performed on a beach or a
rolling ship without prior training and
provide a report of good, fair, or poor
dispersion that is comparable to labora-
tory test results.
The FDET relies on mixing variables
that have been selected as a practical
extension of the turbulence theory to
generate droplet sizes that closely re-
semble the dispersion of oil occuring at
sea. This study determined that a stroke
length of 4 inches, a frequency of 120
cpm, and a shake time of one minute
permitted adequate dispersion of the oil.
A faster or longer stroke raised the
stability of the dispersion, but made the
test physically exhausting. A shorter or
slower shake time made a less stable
dispersion. The shake selected makes
the test easier to perform, more precise
and a better representation of dispersion
at sea.
The settling time also affects the deter-
mination of the dispersion. Measure-
ments after settling for 5 and 15 minutes
do not allow differentiation between a
good and a poor dispersion. The 5-minute
measurement demonstrates insufficient
equilibration of the droplet motion. The
15-minute measurement suffers from the
restriction imposed by the height of the
test tube. The tests showed that only the
10-minute measurement provides a clear
differentiation between good and poor
dispersion.
The FDET results obtained compare
well with the results obtained with the
EPA Revised Standard Dispersant Effec-
tiveness Test (see Figure 2). Prudhoe Bay
oil was tested with fifteen dispersants
using both methods and the effectiveness
values overlapped for eleven out of the
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Oil
10 drops
Dispersant
1 drop
Stroke
LAddoiltowXer
2 Add disperse*
4. Let settle min'
O-ring
Test tube
Flashlight
5. Place on flashlight to position
the O-ring at the Interface
T
fifteen cases. Both methods agreed in
classification of a good dispersion (60-
100%), fair dispersion (20-59%) and poor
dispersion «20%).
All of the oils tested dispersed with
four out of six. dispersants considered.
Eighteen oils were tested for dispersibility
using up to s\x dispersants. Most of the
oils dispersed more than 70% by volume
with a good dispersant but failed to
disperse by more than 40% with a poor
dispersant. Removal of the most volatile
components of the oil and emulsification
with up to 30% water did not change the
dispersibility of the oil.
The FDET has been used to establish a
data base of information on oil dispersibi-
lity and dispersant effectiveness. The
dBase III file covers the physical properties
of the 18 oils tested and their dispersibility
using up to 6 different dispersants. The
data in this file will facilitate proper
selection and application of dispersants
in the field.
6. Measure Interface
7. Move O-ring to visible
Interface
8. Verify Interface
Measurement
Figure 1. The FDET Procedure.
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a FDET—OHMSETT
+ RSDET—PEL
0 RSDET—OHMSETT
Dispersants
Figure 2. Comparison of dispersibility of Prudhoe Bay crude oil effectiveness by FDET and
RSDET.
AnibalDiaz is with Mason & Hanger-Silas Mason Co., Inc., Leonardo, NJ07737.
Richard A. Griffiths is the EPA Project Officer (see below).
The complete report, entitled "A Field Dispersant Effectiveness Test," (Order
No. PB 87-234 886/AS; Cost: $13.95, subject to change) will be available
only from:
National Technical Information Service
5285 Port Royal Road
Springfield. VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Releases Control Branch
Hazardous Waste Engineering Research Laboratory—Cincinnati
U.S. Environmental Protection Agency
Edison, NJ 08837
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
Official Business
Penalty for Private Use $300
EPA/600/S2-87/072
LIBRARY REGION V
60604
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United States
Environmental Protection
Agency
Hazardous Waste Engineering
Research Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S2-87/073 Jan. 1988
Project Summary
Sampling Oil-Water Mixtures
at OHMSETT
Michael Borst
This report describes procedures
developed for sampling oil and water
mixtures.
Two procedures for sampling in con-
tainers are discussed: grab and stratified
sampling. Both of these techniques
require stripping free-standing water
from the container bottom. The grab
sample technique requires that the
remaining fluids be thoroughly mixed
before immersing a bottle through the
resulting homogeneous emulsion. The
stratified sampling procedure uses a
sample thief to capture a segmented
cross-section of the remaining fluids.
Two procedures for sampling flowing
fluids were tested. The two sampling
tubes tested were installed immediately
downstream of a series of static mixers
and a centrifugal pump. The sampling
ports were a simple slotted tube and a
pilot-shaped tube.
This Project Summary was developed
by EPA'* Hazardous Waste Engineering
Research Laboratory, Cincinnati, OH, to
announce key findings of the research
project that It fully documented In a
separate report of the same title (see
Project Report ordering Information at
back).
Discussion
In the documentation of oil spill skim-
mer performance, a measure of the rela-
tive oil/water makeup of collected fluids
is essential. The U.S. Environmental
Protection Agency (EPA) conducted tests
at the Oil & Hazardous Materials Simu-
lated Environmental Test Tank (OHMSETT)
in Leonardo, New Jersey to determine
the usefulness of several techniques to
obtain and analyze representative sam-
ples of oil/water mixtures. Two methods
of sampling containers holding the mixed
fluids and two methods of sampling
flowing streams of the mixed fluids were
tested.
Complete statistical studies were not
conducted, but the tests indicate that the
two methods for sampling containers of
the fluids would give a precision of 3%
oil. The first method entailed thoroughly
mixing the oil and water to form a homo-
geneous emulsion. The sample was then
taken by lowering a bottle through the
emulsion to obtain a 100 ml sample for
later analysis. The second method used a
stratified sampling thief to capture a
representative cross-sectional core of the
fluids. The entire sampler was then sent
to the laboratory for analysis. Tests were
conducted using the stratified sampler to
determine if the complete analysis could
be abbreviated for field application, where
speed rather than accuracy may be the
prime consideration. These tests showed
that, while order-of-magnitude results
could be obtained, significant deterioration
of precision should be expected. The
selection of the method used in the field
would depend on the use of the sample
and support facilities available as well as
the shape of the container sampled.
Two methods of sampling flowing
streams were investigated. One method
used a slotted sampling port; the second
method used a pilot-shaped tube for the
sampling port. In both cases, the sampling
port was located immediately downstream
of an in-line static mixer. The analysis of
samples taken through the two ports
each gave results within the precision of
the comparison technique. The use of the
static mixer to eliminate radial nonsym-
metry in the flowing liquid appears to
make the selection of samples purely
arbitrary.
These tests were performed using only
OHMSETT Circo X medium oil and salt
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water as the immiscible fluids. Highly
viscous mixtures may affect the results
of future application of either of the
stationary techniques. When sampling
materials other than oil and water, chemi-
cal compatibility of the materials with the
sampling device must be considered.
Michael Borst is with Mason & Hanger-Silas Mason Co., Inc., Leonardo, NJ
07737.
Richard A. Griffiths is the EPA Project Officer (see below).
The complete report, entitled "Sampling Oil-Water Mixtures at OHMSETT,"
(Order No. PB 88-102 892/AS; Cost: $11.95. subject to change) will be
available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Releases Control Branch
Hazardous Waste Engineering Research Laboratory—Cincinnati
U.S. Environmental Protection Agency
Edison, NJ 08837
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use S300
EPA/600/S2-87/073
0000329 PS
U S EK¥IR PROTfCTIW AGENCY
REGION 5 LIBRARY
230 S 0IARB«m» STREET
CHICAGO It.
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