United States
Environmental Protection
Agency
Risk Reduction
Engineering Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/S2-91/066 Feb. 1992
EPA Project Summary
Automotive and Heavy-Duty
Engine Coolant Recycling by
Filtration
Arun R. Gavaskar, Robert F. Otfenbuttel, Jody A. Jones, and Paul R. Webb
Product quality, waste reduction, and
economic issues were evaluated for a
chemical filtration technology designed
to recycle automotive and heavy-duty
engine coolants. A fleet-size recycling
unit and a portable unit were evalu-
ated. Coolant recycling was found to
have good potential as a means of
waste reduction and to be economi-
cally viable. Further improvements,
however, are necessary in the product
quality achieved by these units. Prod-
uct quality was evaluated by conduct-
ing selected performance tests recom-
mended in ASTM D 3306 and ASTM D
4985 standards and by chemically char-
acterizing the spent, recycled, and vir-
gin coolants.
This Project Summary was developed
by EPA's Risk Reduction Engineering
Laboratory, Cincinnati, OH, to announce
key findings of the research project
that is fully documented in a separate
report of the same title (see Project
Report ordering information at back).
Introduction
The objective of the U.S. Environmental
Protection Agency (EPA) and the New
Jersey Department of Environmental
Protection's (NJDEP) Prototype Evalua-
tion Program is to evaluate, in a typical
workplace environment, examples of pro-
totype technologies that have potential for
reducing wastes. The goal of the engine
coolant recycling study was to evaluate
(a) the quality of the recycled coolant, (b)
the waste reduction potential of the tech-
nology, and (c) the economic feasibility of
the technology.
In addition to simple filtration and chemi-
cal filtration, distillation and ion exchange
technologies are commercially available
for recycling engine coolant. A separate
study of a distillation unit was also con-
ducted and is presented in a separate
report.
In the study summarized here, two
chemical filtration units (shown in Figure
1), both manufactured by FPPF Chemical
Co., Inc.', were evaluated. The first unit
tested was a fleet-size unit that can re-
cycle up to 100 gal of coolant in one
batch. The second was a portable unit
that can be directly attached to a single
vehicle and recycle the coolant back to
the same vehicle. Both units contain two
filters: a 25-jo. and a 5-u. filter. The
technology also involves the use of aera-
tion to break oil emulsions and form metal
oxides. An additive introduced during re-
cycling precipitates metals in the form of
their hydroxides, inhibits corrosion, reduces
foam, and restores color. The amount of
additive introduced during recycling is
based on the initial pH of the spent cool-
ant.
The study was conducted at the New
Jersey Department of Transportation
(NJDOT) vehicle maintenance and repair
facility in Ewing, NJ. Currently all the
spent coolant at the NJDOT garage (ap-
proximately 8,812 gal/yr) is shipped offsite
for disposal.
' Mention of trade names or commercial products does
not constitute endorsement or recommendation (or
use.
^5 Printed on Recycled Paper
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Product Quality Evaluation
Engine coolants are intended to provide
protection against boiling, freezing, and
corrosion. Through use, the coolants lose
some measure of these functions because
of the accumulation of contaminants and
the depletion of additives such as corro-
sion inhibitors and anti-foam agents. The
recycling process attempts to restore the
functions of the coolant to standards speci-
fied in ASTM D 3306-89 and SAE J1034
(for automotive coolants) and ASTM D
4985 and SAE J1941 (for heavy-duty cool-
ants).
Primary batches of spent coolant (as
received) were run through the fleet-size
unit and the portable unit. The "primary"
batches represented stored spent coolant
from automotive and heavy-duty vehicles
operated by NJDOT. Three "spiked" (al-
tered spent coolant) batches were also
run. The purpose of these salts- and
acid-spiked batches was to create exag-
gerated conditions to test the limits of the
recycling process. A blank, consisting of
virgin coolant and tap water, was run
through the fleet-size unit. Samples of
the spent, virgin, and recycled coolant were
collected for analysis.
Results of the analyses were com-
pared against ASTM and/or SAE stan-
dards. After recycling, the boiling and
freezing points of the coolant were brought
as close to the standard as possible
through the use of a hand-held refractom-
eter and alteration of the glycol to water
ratio. None of the recycled samples from
the primary batches met the corrosion
standards (Table 1), as measured by the
ASTM D 1384 and D 4340 tests. The
spiked recycled samples, however, met
the corrosion standards for the ASTM D
1384 test (Table 2). This variation may
be because the amount of corrosion in-
hibitor added is based on the pH of the
spent coolant. Since the acid-spiked
samples had lower pHs, adding more cor-
rosion inhibitor to the coolant resulted in
better corrosion resistance.
The spent and recycled coolants were
characterized chemically (Tables 3 & 4),
and levels of contaminants, such as met-
als, chlorides, oil and grease, etc., were
measured to determine if these constitu-
ents affected performance. After recy-
cling, although levels of chlorides and sul-
fates were not noticeably reduced in the
coolant, the level of metals was consider-
ably reduced. This retention of chlorides
and sutfates in the recycled coolant may
contribute to corrosion.
Waste Reduction Potential
Waste reduction potential was measured
in terms of volume and hazard reduction.
Volume reduction addresses gross waste
streams (i.e., spent coolant, filters); haz-
ard reduction involves individual pollutants
(i.e., ethylene glycol, heavy metals) con-
tained in the waste stream.
To estimate the amount of coolant that
NJDOT disposes of annually, the amount
of new coolant that NJDOT uses annually
was decreased by 10% to account for the
environmental loss of coolant through leaks
in the vehicles' cooling systems. Because
the coolant is to be recycled rather than
disposed of, the volume of waste reduc-
tion for the NJDOT was calculated to be
8,812 gal. Also accounted for were
sidestreams generated for disposal during
recycling itself (e.g., filters).
Since contaminants contained in the
spent coolant will reach the environment
whether or not the coolant is recycled
(either through spent coolant disposal or
spent filters), the measurable hazard re-
duction comes from the amount of ethyl-
ene glycol that does not reach the envi-
ronment. Ethylene glycol is considered a
hazardous waste in some states (such as
California). Recycling coolant offers con-
siderable potential for reducing the amount
of ethylene glycol released to the environ-
ment.
Economic Evaluation
The economic evaluation took into ac-
count the capital and operating costs
(shown in Table 5) of the recycling equip-
ment, as well as the savings provided by
decreasing the needed amount of raw
materials (virgin coolant, water) and by
reducing disposal costs. Because of the
relatively high price of virgin coolant and
the high volume of virgin coolant pur-
chased by NJDOT, the payback period for
the recycling process was less than 1 yr.
Therefore, effective coolant recycling would
make economic sense.
Conclusions
Although recycling has great waste re-
duction and economic potential, this par-
ticular recycling unit would require addi-
tional improvements to ensure an accept-
able quality of the recycled product. Some
possible areas of improvement are (a) ad-
justing the method of determining the
amount of additive used and (b) imple-
menting a means of anion (chlorides and
sutfates, etc.) removal such as ion ex-
change.
The full report was submitted in fulfill-
ment of Contract No. 68-CO-0003, Work
Assignment No. 0-06, by Battelle under
the sponsorship of the U.S. Environmen-
tal Protection Agency.
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Aerator
100-Gallon
Holding
Tank
Filter A Filter B
(25 microns) (5 microns)
Fleet-Size Unit
o
Outlet Hose
Storage Drum
Storage Drum
\
/A \V fh. /ft*
/(\ \\ v^viLir
1 O *
w W
-—
r
^ ^ f
12 Gallon
Capacity
Unit
%
^%
."",' ""^'
Air
Compressor
Hook-Up
-*•
i
i
-^
*,
I Ion-Exchange
\ Column
J
Filter A Filter B
(25 microns) (5 microns)
\
Compressed
Air
-*•
^ » '
Portable Unit
Figure 1. Coolant Filtration Process
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Table 1. pH (ASTM D 1287-85) and Corrosivity (ASTM D 1384-87) as Measured in Laboratory
Weight Loss per Specimen (trig)**
Batch No. Description
1 Primary
2 Primary
3 Primary
4 Primary
5 Primary
6 Salts Spiked
7 Acid Spiked
8 Salts/Acid
Spiked
9 Blank
Unit
Type'
F
F
F
P
P
P
F
F
F
Sample
Spent
Recycled
Spent
Recycled
Spent
Recycled
Spent
Recycled
Spent
Recycled
Spiked
Recycled
Spiked
Recycled
Spiked
Recycled
Virgin
Recycled
pH*
7.68
11.17
8.41
9.64
8.41
10.32
8.41
11.01
NA
9.87
NA
8.86
NA
10.01
6.21
8.92
8.74
9.23
Copper
2
17
0
20
0
18
0
NA
NA
NA
NA
2
NA
2
4
4
4
3
Solder
2
26
3
4
3
2
3
NA
NA
NA
NA
1
NA
5
0
2
0
2
Brass
2
3
2
11
2
10
2
NA
NA
NA
NA
4
NA
5
8
5
6
6
Steel
1
0
0
0
0
0
0
NA
NA
NA
NA
0
NA
0
229
0
0
0
C. Iron
63
2
30
1
30
48
30
NA
NA
NA
NA
3
NA
3
94
1
0
1
C.AI
3
1
0
0
0
0
0
NA
NA
NA
NA
15
NA
1
1
2
1
3
Type of recycling unit (F = Fleet Size, P = Portable).
SAE Standard for pH 7.5 to 11.0
Average of triplicate results. Triplicates reported in Appendix B.3 of full report. 'NA' indicates not analyzed.
ASTM D 3306 Standard for Corrosion:
Copper * 10 mg max Steel» 10 mg max
Solder - 30 mg max Cast Iron * 10 mg max
Brass - 10 mg max Cast Aluminum = 30 mg max
Table 2. Corrosion of Cast Aluminum Test (ASTM 4340-89) Results
Batch No.
1
4
5
9
Description
Primary
Primary
Primary (Van)
Blank
Unit Type'
F
P
P
F
Sample
Spent
Recycled
Recycled
Virgin
Corrosion Rate *
(mg/crrfl week)
20.2
5.5
22.4
0.9
Type of recycling unit (F « Fleet size, P * Portable).
f SAE Standard: Corrosion rate not greater than 1.0 mg/cm*/week.
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Table 3. Concentrations of Metallic Contaminants in Coolant
ppm in Coolant
Batch
No.
2/3f
2
3
Coolant/Sample
Description
Primary-Spent
Primary-Recycled
Primary-Recycled
Unit
Type'
F
F
F
Aluminum
0.66
2.14
2.01
Calcium
5.6
<1.0
<1.0
Copper
0.49
0.19
0.58
Iron
7.2
4.2
3.7
Lead
1.0
0.37
0.53
Magnesium
1.1
<1.0
<1.0
Zinc
1.4
0.9
0.9
Type of recycling unit (F - Fleet size; P - Portable).
Batches 2 and 3 came from the same storage drum and represent the same spent coolant.
Table 4. Concentrations of Non-Metallic Contaminants in Coolant
ppm in Coolant
Batch
No.
2/3*
2
3
Coolant/Sample
Description
Primary-Spent
Primary-Recycled
Primary-Recycled
Unit
Type'
F
F
F
Chloride
95.5
71.4
75.1
Sulfate
166
149
140
Total Dissolved
Solids
2900
3010
2990
Oil and Grease
307
176
146
Glycolates
511
432
432
Type of recycling unit (F = Fleet size; P = Portable).
f Batches 2 and 3 came from the same storage drum and represent the same spent coolant.
Table 5. Operating Costs Summary
Item
Quantity/yr
Unit Cost ($)
Total Cost ($/yr)
Current Practice
Spent Coolant Storage Drums
Spent Coolant Disposal
Labor for Disposal
Recycling (Fleet-fize Unit)
Make-up Virgin Coolant
Extender (Additive)
Filter A
Filter B
Operating Labor
Operating Energy
Recycling (Portable Unit)
Make-up Virgin Coolant
Extender (Additive)
Filter A
Filter B
Operating Labor
Operating Energy
160
8,812 gal
160 hr
1,234 gal
220 gal
22
11
40 hr
75 k#hr
1,234 gal
167 gal
22
11
441 hr
383 kwhr
30
105/55 gal
15
6.20
1,045/55 gal
11.11
11.11
15
0.12
6.20
1 15/6 qts.
11.11
11.11
15
0.12
4,800
16,823
2,400
7,651
4,180
244
122
600
9
7,651
12,803
244
122
6,615
46
"A-U.S. GOVERNMENT PRINTING OFFICE: 1992 - 648-080/40182
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