ASTM D-15 Committee on Engine Coolants
FIRST REPORT
Task Force on
Antifreeze
Biodegradability
.' First
Brands Report 1
LETTER ON "FIE SUBJECT OF DISPOSAL OF USED
ETHYLENE GLYCOL ANTIFREEZE S O L U T I O F
In response to your inquiry regarding the biodegradability of ethylene
glycol base antifreeze, we offer the following comments.
As you may know, biodegradability expresses the degree to which a compound is broken down by microorganisms. During this process, organic materials
are oxidized and oxygen is consumed. The amount of oxygen used is called the
biochemical oxygen demand (BOD), and it can be measured in the laboratory by
incubating a sample of the material with domestic sewage. Biodegradability is
then calculated by comparing the amount of oxygen consumed in the BOD test with
the theoretical amount required to completely oxidize the material to carbon
dioxide and water.
BOD tests conducted by a major producer and at an outside laboratory with
uninhibited ethylene glycol and inhibited antifreeze have established that the
materials are completely biodegradable. The time required for complete break
down cannot be predicted from BOD test data because it depends upon the efficiency
of the sewage treatment plant and the type of bacteria present. Even if the glycol received no treatment, it would be degraded in the existing surface waters
which contain a variety of indigenous microorganisms and a supply of oxygen. If
discharged to the ground, the microbial and filtering action of the soil and rock
strata will purify the waste material.
Some time ago a study was made of how much ethylene glycol originating from
drained coolants might be found in waste waters. Data were obtained for four
metropolitan areas and calculations were made under hypotlietical conditions in
which all of the discarded antifreeze was drained in a one-week period. The calculations showed that the level of ethylene glycol in the metropolitan waste
waters would be in the approximate range of 370 to 530 parts per million; levels
well below the published aquatic toxicity threshold values of 1,000 to 10,000 ppm
for ethylene glycol.
8
In real life, where drainings are made over a considerably longer period of
time, levels are much lower. Moreover, when taking into account the established
biodegradability of ethylene glycol, the concentrations in metropolitan discharges
into receiving waters will be very low o r nonexistent.
In summary, the used coolant drained every year presents no threat to the
environment whether it be drained into sanitary sewers, storm sewers, surface
waters, o r directly into the ground. In all cases the ethylene glycol is broken
down into harmless carbon dioxide and water.
2
Ecolosical Aspects of PRESTONE Antifreeze and Ethylene Glycol
summary:
In its simplest terms, biodegradability expresses the
degree-towhich a compound is reduced in structural complexity by
the action of microorganisms in a natural, or natural-simulated,
environment.
PRESTONE Antifreeze and its base liquid ethylene glycol, have
been subjected to many biodegradation procedures
including
those described in the Standard Methods For The Examination of
water and Wastewater, 15th Edition, American Public Health
(1980)
The
testing results indicate
rapid
Association
biodegradation of both antifreeze and ethylene glycol, and their
amenability to standard septic tank or municipal waste disposal
and treatment.
.
Toxicity studies carried out on selected indicator species of
aquatic life suggest a l o w order of toxicity in
aqueous
concentrations up to 2 grams per litre.
No
studies have been reported on the effect of PRESTONE
Antifreeze and ethylene glycol on plant life.
I.t is recognized,
however, that high concentrations of any water-soluble liquid may
cause some injury to many varieties of plant life.
The natural
dilution that occurs when antifreeze is disposed of into septic
or municipal treatment pipelines should minimize, or eliminate,
irreverisble plant toxicologial effects.
b
In conclusion, PRESTONE Antifreeze may be discharged into septic
tank and municipal waste treatment facilities, wherein natural
biodegradation
readily
destroy
the should
chemical
composition.
Ofprocesses
course,
local water
officials
be
contacted to ensure that any contemplated disposal scheme is in
concert with all applicable area regulations.
DAMcKenzie/dn
3
TECHNICAL SERVICE REPORT
ECOLOGICAL ASPECTS OF PRESTONE ANTIFREEZE AND ETHYLENE GLYCOL
UNION CARBIDE CORPORATION
' I
HOME AND AUTOMOTIVE PRODUCTS DIVISION
DECEMBER 1, 1985
4
ECOLOGICAL ASPECTS OF PRESTONE ANTIFREEZE AND ETHYLENE GLYCOL
SUMMARY
The
information contained
in this
report
PRESTONE Antifreeze and ethylene glycol are readily
and relatively nontoxic to aquatic life.
or
shows that
biodegradable
Disposal of used product,
wastewater containing these materials, may be accomplished
discharging
them
to
septic tank or municipal
waste
facilities (biological or physical/chemical treatment).
by
treatment
The
compatibility of these disposal procedures with Federal, State, and
the
environmental regulations existant in your local
.
area
first
should be verified with local authorities.
Please
refer
to
our
current Material
Safety Data
Sheets
for
b
additional information.
Biodesradabilitv
+,
In
degree
its
simplest terms, biodegradability
to which a compound is reduced in structural complexity by
the action of microorganisms.
Control
expresses the
Federation(’)
has
A committee of the Water
suggested three
Pollution
different terms to
describe biodegradation.
5
Primary
Biodesradation:
Biodegradation to the minimum
extent necessary to change the identity of the compound.
Environmentallv Acceptable Biodesradation:
tion to the minimum extent necessary
sirable properties
to
Biodegradaremove under-
of the compound such as
foaminess
and/or toxicity.
Ultimate
Biodesradation:
Biodegradation
to
inorganic
end products.
Several quantitative expressions are commonly used to describe
the biosusceptibility of organic matter:
Biochemical Oxysen Demand
.
When aerobic bacteria oxidize organic matter,
consumed
during
the process
and
the
amount
required
proportional to the amount of organic material present.
as
oxygen is available,
oxygen is
is
As
long
aerobic microbial decomposition of
the
organics will continue until the oxygen demand is satisfied; that
-,
is, until
the
aerobic microorganisms have oxidized all of
organic material they are capable of oxidizing.
The amount
the
of
oxygen used during this process is the biochemical oxygen demand
(BOD).
Chemical Oxvsen Demand
The
organic
6
amount of oxygen required to completely oxidize
material
to
carbon dioxide and water is known as
an
the
chemical oxygen demand (COD).
theoretical basis,
This value may be calculated on a
knowing the
composition of
the
organic
If the chemical structure is not known, COD can be
material.
determined by a standard dichromate oxidation procedure ( 3 )
.
BOD Test Procedure
For measurement purposes,
quantity
the
stabilization of
water-bourne substances under a specific set of test conditions.
The
of
BOD is considered to be
most
oxygen required for biological
common
test is the 5-day BOD(*),
A
sample of
the
for 5 days in the
presence of a selected biota consisting principally of bacteria.
comparison of the dissolved oxygen content of the sample at the
material
to
be
tested is incubated at
20°C
beginning
and end of the incubation period provides a measure of
the BOD.
Because the solubility of oxygen in water is very low,
about
ppm
9.2
diluted
to
the
at
2OoC,
the material to be tes-ted has
L
low ppm range in
order to
avoid
to be
completely
depleting the dissolved oxygen during the 5-day test.
Few, if any, materials are cgmpletely degraded during
the 5-day test.
When the test is continued beyond 5 days, until
the material is oxidized as completely as possble,
the result is
*,
termed
an ultimate BOD.
observed
Determination of ultimate BOD has been
to require approximately 20 days for most materials
at
the dilutions normally employed in the test.
7
The
microorgansms
and
water
and/or
oxygen
consumed
during the test is used
to oxidize carbonaceous matter to
and
to oxidize nitrogenous matter
nitrate
ions.
The
oxidation of
by
the
carbon dioxide
to
nitrite
nitrogen
ions
can become
particularly important in the longer-term BOD tests but generally
does not occur during the 5-day test.
The most commonly employed source of microorganisms for
use in the BOD test is domestic sewage. When an organic material
is not
commonly found in nature,
as is the
case with
many
petrochemicals, sewage microorganisms can be slow to attack the
material,
and the BOD test results may be lower than experienced
in nature.
Adaptation (termed nacclimationti)of microorganisms
to the organic material can often result in an increased rate and
Acclimation refers to the
extent of oxidation of the materials.
process of contacting a microbial culture with a material in such
a
way as to permit an increase in the number of those organisms
in the culture which have the ability to oxidize and utilize
the
b
material,
as
well
as
permitting the
organisms to
tlgear-uptt
enzymatically for the oxidation and utilization of the material.
In general,
treatment
it can be assumed that a biological waste
facility, which
has been receiving a material for a
long period of time, is acclimated to that material.
can be
lost
if the material only
biological waste treatment facility.
8
Acclimation
intermittently enters
the
The concentrations of organic material and microorganisms are
much
BOD
higher in a biological waste treatment system than
tests.
These higher concentrations result in an
different set
rapid
rate
of reaction kinetics and generally
of
BOD
exertion.
For
example,
a
a
in the
entirely
much
more
conventional
sludge biological waste treatment system can remove as
activated
much as 90 percent of the 5-day BOD in 6 to 12 hours.
Measurement of Biodeqradabilitv
P
Biodegradability
different means,
can be
measured
through
several
for example, through the disappearance of foam-
producing properties as in detergents, or a change in some other
physical
property.
One
quantitative method
of
expressing
in
biodegradability is to compare the amount of oxygen consumed
the
standard
BOD
test with the amount of
r
oxygen
required
to
completely oxidize the material to carbon dioxide and water on
theoretical basis.
For example, the theoretical oxygen demand of
b
ethylene glycol is calculated as indicated below:
indicated below:
2HOCH2
CH OH
Ethylene zlycol
MW
=
62
a
+
5 0 2 7 4 COi
Oxygen
Mw = 32
mq EG
X mg 0,
2 x 62
5 X 32
Theoretical Oxygen Demand =
+
H20
5 x 32 =
2 x 62
1.29 mg 02/mg EG
9
The measured
5-day BOD of ethylene glycol is
mg
0.465
02/mg EG, or 36 percent of the theoretical oxygen demand(5)
Simlarly, the measured 20-day BOD is 1.39 mg 02/mg EG which
100
percent of the theoretical oxygen demand.
In a
system, some of the organic material is incorporated
microbial
,
and
percent
of the theoretical oxygen demand is onlf
water,
the 20-day period.
whether
biological
into new
cells rather than being completely oxidized to
dioxide
or
not
and
thus oxygen consumption equal
carbon
to
100
approached
a material
is biodegradable, some arbitrary
of the theoretical oxygen demand must be selected
the
point
test would
material
biodegradable
and
seem
to be an acceptable rate of
as
non-biodegradable
in .the 20-day BOD
oxidation
for a
to be classed as biodegradable in most instances where
this type
cases,
between
A minimum of 50 percent oxidation
materials.
in
Therefore, in making a judgement concerning
percentage
break
is
of data need to be
either higher
reasonable
or
employed.
lower percent
However,
in
special
oxidations could
be
for the break point between biodegradability and non+,
biodegradability.
It
should
be
noted that the extent of
removal
material in a biological waste treatment system cannot be
predicted from BOD test data.
the
percent
In general, however,
a
easily
the higher
oxidation in 5- and 20-day BOD tests, the
greater
would be the removal in a biological waste treatment plant.
10
of
The
h
importance of acclimating a biological waste treatment system to
a
given waste
or waste constituent cannot be
overemphasized.
Acclimation can increase the rate and extent of bio-oxidation as
well
as aiding in overcoming inhibitory
or toxic effects of an
organic material.
Biodesradabilitv of PRESTONE Antifreeze and Ethylene Glycol
A
comparative set of
PRESTONE Antifreeze
Data
on
and ethylene glycol
the biodegradability
as
a
percent
of
chemical oxygen demand are presented below:
Product Tested
PRESTONE
Antifreeze
Chemical Oxygen
Demand (COD), m s / m
Theoretical
Measured
1.24
1.25
Measured Bio-oxidation
as Percent of
Chemical Oxvqen Demand(b1
Day 10
Dav 20
Day 5
.
21
69
04
14
62
75
b
Ethylene Glycol
(a)
1.30
1.39
Measured chemical oxygen demand value was determined by
-,
catalyzed chromic acid procedure outlined in Standard
Methods for the Examination of Water and Wastewater(3).
(b) Bio-oxidation data are calculataed from chemical oxygen
demand
11
data obtained by procedures outlined in Standard
Methods(*).
Calculation is:
BOD
XlOO
chemical oxygen demand
Reported value
is the percentage ratio of BOD
to
the
total COD.
(c)
The
difference between 21 and 14 percent at Day
caused
by
(domestic
variation
waste
is
The
microorganisms).
in biological
seed
employed
a
as
difference
5
is
activity
source
in seed
of
activity
can result in significant variation in percent oxidation
in the early stages of the test.
The
above results
indicate rapid
PRESTONE Antifreeze and straight ethylene
biodegradation
glycol. .
The
of
BOD
test simulates river conditions and consequently is a very dilute
biological
system.
this test
environment may correspond to only a few hours
A
biodegradation period of 5 to 10 days
conventional biological waste treatment facility.
Thus,
anticipated that the PRESTONE Antifreeze and ethylene
-,
in
in a
it is
glycol are
readily amenable to biological waste treatment.
However, because
these materials are biodegradable,
represent a
quantities
could
receiving
streams ( 5 )
Oxygen
large
significant oxygen demand
in
depletion of
is
the
stream
proportional to the biodegradability of the material added; i.e.,
materials with high biodegradability cause high oxygen depletion.
In a natural stream, the oxygen is provided from the dissolved
12
oxygen
in the water or waste.
exceed
about
14
ppm
and
Because dissolved oxygen
is usually
cannot
less than half
that
concentration, it is apparent that the oxygen demand of a strong
waste can be satisfied or destroyed only by dilution with a large
amount
of oxygen-bearing water or by abundant replenishment of
dissolved
the
oxygen either by photosynthesis or by absorption
atmosphere.
If the
dissolved
oxygen
is
from
depleted,
microorganisms will use conbined oxygen from nitrate, nitrite,
and sulphate ions from organic compounds in the waste or from the
water
molecule
compounds such
itself, resulting in the formation of
as methane and hydrogen,
instead of the
gaseous
carbon
dioxide and water formed under aerobic conditions.
Aquatic Toxicity of Ethylene Glvcol and Related Products
Aquatic
ethylene
toxicity
tests on PRESTONE Antifreeze
glycol have shown both to
and
be non-toxic to an indicator
b
organism
(the brine shrimp Artemia Salina) at concentrations in
excess of 20,000 mg/liter.
ethylene
glycol
Measured aquatic toxicity values for
and PRESTONE Antifreeze with
were greater than 10,000 mg/liter.
(concentraton lethal for
fathead minnows
Substances having LC50 values
percent of- ,the minnows exposed) in
this concentration range are generally considered relatively non50
toxic.
E f f e c t on Plant Life
No
study
appears to have been made on the
ethylene glycol on plant life.
-
-
of
However, many people are aware of
the herbicidal properties of organic liquids.
to
effect
It is reasonable
state that higher concentrations of any water-soluble liquid
would
probably cause injury to many representative plants.
-The
13
would
probably cause injury to many representative plants.
natural dilution
occurring when ethylene glycol based
The
products
are disposed of would minimize this problem.
The greatest risk
would
into the planted
occur when
undiluted runoff may flow
areas.
REFERENCES
1.
Standard
Methods
Committee
- Subcommittee on
Biodegradability, J. Water Pollution Control Federation,
39, p. 1232 (1967).
2.
llAerobicBiological Treatment of Waste Waters, Principles
and Practice,I1 A. W. Busch, Oligodynamics Press, Houston,
Texas, 1971, p. 152.
3.
Chemical Oxygen Demand procedure published in Standard
Methods for the Examination of Water and Wast'ewater, 15th
Ed, Am Public Health Association, (1980).
4.
Biochemical Oxygen Demand procedure publised in Standard
Medhods for the Examination of Wate and Wastewater, 15th Ed,
Am Public Health Association, (1980).
5.
ttAqueousWastes from Petroleum and Petrochemical Plantsv1,
M. R. Beychok, Wiley, 1967, p. 38.
. . ..- - . ..
'.
14