United States
Environmental Protection
Agency
Risk Reduction
Engineering Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/SR-92/024 April 1992
EPA Project Summary
Automotive and Heavy-Duty
Engine Coolant Recycling by
Distillation
Arun R. Gavaskar, Robert F. Olfenbuttel, and Jody A. Jones
Product quality, waste reduction, and
economic issues were evaluated for a
distillation technology designed to re-
cycle automotive and heavy-duty en-
gine coolants. Coolant recycling was
found to have good potential as a
means of waste reduction and to be
economically viable. The product qual-
ity achieved by this unit was promis-
ing. Product quality was evaluated by
conducting selected performance tests
recommended in ASTM D 3306 and
ASTM D 4985 standards and by chemi-
cally characterizing the spent, recycled,
and virgin 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.
The coolant recycling unit in this study
was manufactured by Finish Thompson,
Inc. (FTI)', Erie, Pennsylvania. The unit
' Mention of trade names or commercial products does
not constitute endorsement or recommendation for
use. This document is intended for informational
purposes only for the automotive repair industry.
(shown in Figure 1) operates on up to 15
gal of spent coolant per batch. Spent
coolant is poured into the distillation still
along with an additive to control boiling.
The unit is switched on and allowed to
operate until water and ethylene glycol
are distilled off into two separate clean
drums outside the unit. This may take
.between 12 and 15 hours for a full 15-gal
load of spent coolant, depending upon the
amount of water present. Water distills
out first at atmospheric pressure. As the
temperature rises,,the vacuum pump
switches on automatically and starts draw-
ing out the glycol. The vapors are con-
densed by using tap water as the heat
exchanger fluid. A chiller is available as
an option, but was not used in this testing.
The condensate enters the primer tank,
where it mixes with the primer (ethylene
glycol) and overflows into the "processed
glycol drum". Three gallons of distillation
residue collects at the bottom of the still
and is emptied out, typically after five
batches.
The study was conducted in coopera-
tion with the New Jersey Department of
Transportation (NJDOT) vehicle mainte-
nance and repair facility in Ewing, NJ.
Currently all the spent coolant at the
NJDOT garage (approximately 8, 812 gal/
yr) is shipped offsite for disposal.
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 coolant) and ASTM D 4985
and SAE J1941 (for heavy-duty coolants).
Printed on Recycled Paper
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Pump
Optional
Water Chiller
Figure 1. Coolant cSstillation process.
In addition to running batches of spent
coolant (primary batches), test batches in
which one or more characteristics of the
coolant were intentionally altered (spiked
batches), were run to test the limits of the
recycling process. All batches, except
Batch 5, consisted of spent coolant ob-
tained from NJDOT. Batch 5 was spent
coolant obtained from a local radiator shop.
A blank, consisting of equal portions of
virgin coolant and tap water, was also run
through the unit. Samples of the virgin,
spent, and recycled coolant were collected
for analysis.
Batches 3 and 4 were run at less-than-
full capacity to conserve time and materi-
als. Because both units shut off while 3
gal of residue remained, as they are pro-
grammed to do, there was not enough
recycled coolant for sampling from each
individual batch. Hence, residue from
Batches 3 and 4 was combined and re-
run. This combined batch is henceforth
referred to as Batch 3/4.
Results of the analyses were compared
against ASTM and/or SAE standards. Af-
ter recycling, the freezing point was mea-
sured by a hand-held refractometer, and
the ratio of processed water to processed
glycol was adjusted accordingly to meet
freezing point specifications. As shown in
Tables 1 and 2, the pH and corrosiveness
of the recycled coolant were also within
specified limits.
The spent and recycled coolants were
characterized chemically and contaminant
levels were measured to determine if these
constituents affected performance. Table
3 shows the ilevels .of metallic contami-
nants. The levels of calcium, magnesium,
iron, and zinc:were reduced considerably
in the recycled coolant. Reduction in lev-
els of lead and aluminum could not be
estimated because of |ow levels of these
metals in the, spent coolant and due to
matrix interference in the analysis.
One limitation of this product quality
evaluation was that the performance of
the recycled : coolant from successive
batches processed on the same recycling
unit could not be assessed because the
five batches were run on five separate
units. Evaluation of the recycled coolant
obtained after,running several batches on
the same unit would be a good adjunct to
this study, especially because the primer
(ethylene glycbl) in the primer tank has a
diluting effect on the initial batches. Later
batches may have slightly higher levels of
contaminants.
Waste Reduction Potential
Waste reduction potential was measured
in terms of (a) volume reduction and (b)
pollutant reduction. Volume reduction ad-
dresses the gross waste streams (i.e.,
spent coolant and spent filters); pollutant
reduction involves individual pollutants
(such as ethylene glycol and heavy met-
als) contained in the waste stream.
To estimate the amount of coolant that
NJDOT disposes of annually, the amount
of new coolant that NJDOT purchases
annually was i decreased by 10% to ac-
count for the environmental loss of cool-
ant through leaks in the vehicles' cooling
systems. Because the coolant is recycled
rather than disposed of, the volume of
waste reduction for NJDOT was calcu-
lated to be 8,812 gal. The side streams
of the recycling process (residue) were
also accounted for in this evaluation.
Since contaminants (e.g., lead) con-
tained in the spent coolant will reach the
environment whether or not the coolant is
recycled (either through spent coolant dis-
posal or residue disposal). The measur-
able hazard reduction of recycling comes
from the amount of ethylene glycol that
does not reach the environment or find its
way to disposal. Ethylene glycol is con-
sidered a hazardous waste in some states
(such as California). Recycling coolant
offers considerable potential for reducing
the amount of ethylene glycol released to
the environment.
Economic Evaluation
The economic evaluation took into ac-
count the capital and operating costs
(shown in Table 4) of the recycling equip-
ment, as well as the savings provided by
decreasing the needed amount of raw
materials (virgin coolant and water) and
by reducing disposal costs. The purchase
price of the recycling unit at the time of
this evaluation was $5,115. 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 much less than
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Table 1. pH (ASTM D 1287-85) and Corrosivify (ASTM D 1384-87) As M
Batch No. Description Sample' pH"
1,2 Primary
1 Primary
2 Primary
3/4 Spiked
5 Primary
Spent
Recycled
Recycled
Spiked
Recycled
Recycled
8.3
10.9
11.0
8.7
10.7
10.8
easured in Laboratory
Weight Loss per Specimen (ma)*"
Copper
0
0
0
0
0
0
Solder
2
4
6
4
6
7
Brass
1
3
1
2
2
1
>- Steel
0
1
0
0
0
o
C. Iron
4
2
0
72
1
1
C.AI
1
5
1
1
0
0
a A recycled sample indicates 50:50 processed glycol and processed water, plus additives. No spent sample analyzed for Batch 5.
" SAE Standardfor pH 7.5 to 11.0
c Average of triplicate results.
° ASTM D 3306 Standard for Corrosion:
(allowable weight loss per specimen)
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.
1,2
1
2
Description
Primary
Primary
Primary
Blank
Sample '
Spent
Recycled
Recycled
Virgin
Corrosion Rate
mg/crrf/wk"
16.8
0.8
0.9
0.9 .
* A recycled sample indicates 50:50 processed glycol and processed water, plus additives. " •'-• ''
" SAE Standard: Corrosion rate not greater than LOmg/crrf/wk
Tables. Concentrations of Metallic Contaminants in Coolant
ppm in Coolant* , ,
Batch No.
1,2,3/4
1
2
3/4
5
Description
Primary
Primary
Primary
Spiked
Primary
Sample '
Spent
Recycled
Processed
water
Recycled
Recycled
Processed
glycol
Aluminum
<0.19
0.63
<0.19
0.88
1.01
1.20
Calcium
0,46
<0.20
<0.20
<0.20
<0.20
<0.20
Copper
2.34
0.081
<0.036
0.32
0.21
0.15
Iron
0.28
<0.04
0.04
0.04
0.63
0.098
Lead
0.34
2.88
<0.2
1.0
1.59
2.9
Magnesium
0.78
<0.20
<0.20
<0.20
<0.20
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1 yr. Therefore, coolant recycling would
make economic sense.
Conclusions
This evaluation shows that automotive
coolant recycling has much potential as a
waste reduction option. The NJDOT facil-
ity where this evaluation was conducted
could potentially reduce spent coolant
waste volume from over 8,000 gal to ap-
proximately 400 gal/yr. The recycled prod-
uct in this evaluation also fared very well
in the selected ASTM performance tests
and the chemical characterization analy-
ses. Boiling point, freezing point, pH, and
corrosion resistance functions of the cool-
ant were restored to specifications. Met-
als, salts, and organic contaminants were
considerably reduced in the recycled cool-
ant. Recycling was found to be economi-
cally viable for the NJDOT facility, with a
return on investment (ROI) of over 300%
in the first year.
Figure 2 describes how the ROI varies
depending on the amount of spent cool-
ant generated annually by the user. If a
user generates 100 gal of coolant annu-
ally, the initial investment may not be re-
coverable. A slightly larger generator, with
500 gal/yr of spent coolant, would have a
payback period of approximately 7 yr (ROI
greater than 15%). The ROI improves as
the amount of spent coolant generated
becomes larger. The manufacturer plans
to improve economics by reducing the
heating requirement and also by eliminat-
ing the No Foam™ additive in the 1992
model of this unit. Also, as regulations
become more stringent, the economical
attractiveness of the technology can be
expected to grow.
The full report was submitted in fulfill-
ment of Contract No. 68-CO-0003, Work
Assignment 0.06, by Battelle Memorial In-
stitute under the sponsorship of the U.S.
Environmental Protection Agency.
Table 4. Major Operating Costs
Item
Quantify/yr
Unit Cost, $
Total Cost, $fyr
Current Practice
Disposal:
• Coolant 8,812 gal
• Drums 160
• Labor (no overheads) 160 hr
Recycling
No-Foam™ (additive) 700 bottles
FTI Treatment™ (additive) 700 bottles
Water (for condenser, flush) 252,140 gal
Electricity 35,990 /cwfr
Labor (no overheads) 257 hr
Residue Disposal 420 gal
Drums 8
$140/
55 galdrum
30
15
1.86
8.60
.0011
.12
22,431
4,800
2,400
$4SO/
55 gat drum
30
Total 29,631'
1,302
6,020
277
4,319
3,855
3,436
240
Total 19,449=
' This total does not include maintenance costs or overhead.
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I
1
I
500
400
300
200-
-700
Coolant = 7000 gal
A
Coolant = 500 gal
100-
Year
10
Figure 2. Summary of ROI for various sizes of shops generating spent coolant.
•frll.S. GOVERNMENT PRINTING OFFICE: 1992 - 648-080/40Z36
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A.R. Gavaskar, R.F. Olfenbuttel, andJ.A. Jonesare with Battelle Memorial Institute,
Columbus, Ohio 43201-2693.
Paul Randall is the EPA Project Officer (see below).
The complete report, entitled "Automotive and Heavy-Duty Engine Coolant Recy-
cling by Distillation," (Order No. PB92-153 444/AS; post: $19.00, 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:
Risk Reduction Engineering Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
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/SR-92/024
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