United States
Environmental Protection
Agency
Risk Reduction
Engineering Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/SR-93/154 September 1993
Project Summary
A Fluid Sorbent Recycling
Device for Industrial Fluid Users
Abraham S. C. Chen, Robert F. Olfenbuttel, and Brian T. Cano
This evaluation addresses the prod-
uct quality, waste reduction, and eco-
nomic issues involved in recycling fluid
sorbent pads. A roller compression
Extractor™* that extracts fluids from re-
usable sorbent pads was evaluated as
a method of waste reduction. The ex-
traction device, evaluated for industrial
fluid users in New Jersey, was found
to be effective in recycling unpleated
sorbent pads, especially when used for
low-viscosity fluids. The unpleated sor-
bent pads can be reused at least eight
times for low-viscosity fluids and up to
three times for medium-viscosity flu-
ids. The Extractor™ cannot, however,
be used for pads soaked with high-
viscosity fluids. The annual savings in
dollars can be substantial: 51% to 75%
savings would be possible if pads are
reused two and eight times, respec-
tively. The cost per use can be as low
as $1.19 for eight reuse cycles, versus
$4.80 for single use. The savings come
primarily from cost reductions in sor-
bent pad disposal.
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's (EPA) Waste Reduc-
' Mention of trade names or commercial products does
not constitute endorsement or recommendation for
use.
tion Innovative Technology Evaluation
(WRITE) Program is to evaluate, in a typi-
cal workplace environment, examples of
prototype technologies having the poten-
tial to reduce wastes at the source or to
prevent pollution. The goal of this study
was to evaluate a technology that extracts
fluids such as mineral oils, cutting fluids,
and solvents from sorbent pads by roller
compression. Specifically, this study evalu-
ated (1) the waste reduction potential of
this technology, (2) the quality of the re-
cycled pads, and (3) the economics.
In the process of mixing, handling, and
packaging of fluids, spills occasionally oc-
cur. At the end-users' sites, the fluids may
be spilled or cutting oils splattered during
their use in the machining process. Cur-
rently, the spilled or splattered fluid is re-
moved by hand with sorbent pads made
of melt-blown polypropylene. Workers sim-
ply lay the pads over the spilled fluid and
mop the spilled areas. Once the pads are
saturated with fluid, they are drummed for
disposal.
During the evaluation the Extractor™,
manufactured by Environmental Manage-
ment Products, was used to recover the
spilled fluid from the saturated sorbent
pads. The Extractor™ recovered the fluid
by compressing the pads between two
gear-driven counter-rotating rollers. The
desaturated sorbent pads were then re-
used several times until the quality of the
pads degraded, no longer retaining fluid
or providing a clean surface.
The evaluation of the roller compres-
sion Extractor™ was performed at Cook's
Industrial Lubricants, Inc., in Linden, NJ.
Cook's Industrial Inc. is a custom blender
Printed on Recycled Paper
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industrial lubricants with 450 active for-
jlas on the market. The plant occupies
proximately 50,000 ft2 and employs ap-
Dximately 20 full-time workers.
aste Reduction Potential
/aluation
Two types of waste were considered in
s study—spent sorbent pads and waste
id. The current practice is to dispose of
3 spent pads after one use. The roller
mpression method extracts the sorbed
id and permits reuse of the pads. Al-
)ugh the extracted fluid is contaminated
:h the dirt and debris picked up during
3 spill, it may be processed for reuse.
erefore, this technology has the possi-
ity of reducing the number of sorbent
ds used and the volume of sorbent pads
d fluids sent to disposal. Although new
ds are not hazardous, the fluid sorbed
them may be. Because the pads take
the characteristics of the sorbed fluid,
d recycling can reduce the volume of
zardous waste disposal.
The extraction efficiency test (ASTM
andard Method F726-81) was used to
termine the number of extraction cycles
sorbent pad could endure before be-
ming unusable due to tearing, deform-
3, or other general deterioration. The
>t was also used to examine the rate of
decrease in the pads' sorbing capacity (or
adsorbency ratio) and the percentage of
fluid to be removed by roller compression.
Because fluid removal is dependent on
the fluid viscosity, tests were conducted
with three different fluids covering a range
of viscosities.
The average adsorbency ratio and ex-
traction efficiency for low viscosity fluid is
plotted against the extraction cycle in Fig-
ures 1 and 2. The average adsorbency
ratio was 13.99 g to 14.79 g of fluid/g of
sorbent pad dry weight (equivalent to 1.44
to 1.48 qt of fluid per full-size pad). The
sorbing capacity decreased 18.4% to
21.6% after one extraction cycle and
32.7% to 36.0% after three cycles. No
additional decrease was observed up to
eight cycles. The percentage of fluid re-
moved by the extraction device (or the
extraction efficiency) from the fresh sor-
bent pads ranged from 82.1% to 83.3%.
Subjecting the pads to the Extractor™ for
3 and 7 more cycles resulted in only 3.5%
to 4.4% additional reduction in extraction
efficiency. After 8 extraction cycles, the
pads were compressed, and, in some
cases, a thin web of fibers clung to the
roller during extraction.
The sorbent pads were also effective
for medium-viscosity fluid, as indicated by
the adsorbency ratio (17.65 g/g or 1.64 qt
per full-size pad) and extraction efficiency
(80.8%). After extraction, however, some
peeling and slight deformation were ob-
served. The deformation and separation
became so severe after the second or
third cycle that the pads had to be dis-
carded. The sorbent pads had an
adsorbency ratio of 17.83 g/g (or 1.6 qt
per full-size pad) for high-viscosity fluid.
The fully saturated pads, however, failed
to pass through the Extractor™ even at a
significantly reduced roller pressure.
Product Quality Evaluation
The quality of the sorbent pads might
be degraded by the extraction process.
To determine product quality, both quanti-
tative and qualitative aspects of pad deg-
radation were examined. Degradation of
pad quality was quantified using the rate-
of-release test (ASTM Standard Method
F716-82).
The original test method involved satu-
rating a fresh sample pad with one of the
three fluids, weighing it even if still drip-
ping, and hanging it by one corner until
dripping stopped. Regardless of fluid types,
dripping continued at a rate of 5 to 15
drops per min by the end of 2 hr. There-
fore, the reweighing of the pad took place
without further waiting. The fluid sorbed
per unit dry weight of the pad was re-
I
0)
-p
16 —
15 —
14 —
13 —
12 —
11 —
10 —
9 —
8 _
Four extraction cycles
Eight extraction cycles
4 5
Extraction cycle
gure 1. Adsorbency ratio for low-viscosity fluid.
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86
84
82 —
80 —
78
76
74
Four extraction cycles
Eight extraction cycles
4 5
Extraction cycle
Figure 2. Extraction efficiency for low-viscosity fluid.
corded as maximum practical pickup
(MPP). The pad was rehung in a well-
ventilated area using an electrical fan and
weighed at 10-min intervals for 1 hr. (Note:
the ASTM Method calls for up to 2 hr of
interval weighing; 1 hr was selected for
this study.) Again, dripping from the pad
continued at a similar rate. The fluid re-
tained at the end of 1 hr was recorded as
maximum effective pickup (MEP).
The MPP and MEP of new pads were
compared with those of pads that had
passed through the Extractor™ four and
eight times, respectively. If the used pads
had a different rate of release, the test
indicated degraded pad performance.
The ability of sorbent pads to leave a
clean floor after use was measured by the
fluid pickup test. The percentage of pickup
by a new pad was compared with that of
recycled pads.
The results of the rate-of-release tests
are given in Table 1. The MPP and MEP
of the fresh pads for the low-viscosity fluid
were 6.19 and 5.21 g/g, respectively. The
decrease in MPP was 23.6% and 28.9%
for pads reused for four and eight times,
and the decrease in MEP was 24.8% and
31.1%, respectively. Although the pad per-
formance was degraded by approximately
25% after four uses, the degradation in
performance was relatively insignificant for
4 additional uses. For the medium- and
high-viscosity fluids, the MPP and MEP
were measured only for the fresh sorbent
pads.
The results of the fluid pickup tests are
presented in Table 2. Regardless of fluid
types, the sorbent pads effectively re-
moved fluids from the floor. Only 2.4% to
5.2% of the spilled fluids were left on the
floor. Moreover, the sorbent pads effec-
tively removed low- and medium-viscosity
fluids even after they were reused four or
eight times.
Economic Evaluation
The objective of comparing costs of pad
disposal versus reuse was met by using
fluid capacities and process time mea-
sured during the study and supplemented
by literature and company historical data.
For low-viscosity fluid, substantial savings
occurred as a result of pad recycling. Sav-
ings of up to 51.4% and 75.3% were pos-
sible with as few as two and as many as
eight reuse cycles, respectively. Additional
savings were also possible, but much less
significant, as reuse cycles increased to
more than eight times. Similarly, the cost
per use was greatly reduced, from $4.80
for single use to $1.19 for eight uses (see
Figure 3). For medium-viscosity fluid, the
annual pad recycling savings were 50.5%
and the per use cost was $2.38 for two
uses. Additional uses and savings are very
unlikely because the sorbent pads became
severely separated and deformed as a
result of the extraction process. Because
the capital cost for the Extractor™ was
relatively insignificant ($699) and the an-
nual savings would be substantial, the
payback period of the investment would
be only 2.8 to 5 weeks.
Conclusions
The sorbent pad recycling evaluation
demonstrated that roller compression tech-
nology can be effectively used to extract
low- and medium-viscosity fluids from melt-
blown polypropylene sorbent pads. The
Extractor™ is particularly useful for low-
viscosity fluid applications; the sorbent
pads can be reused at least eight times.
For medium-viscosity fluids, no more than
two to three reuse cycles are possible.
The potential to reduce waste by recy-
cling sorbent pads can be substantial. For
example, for a 1,858-m2 (20,000-ft2) plant,
annual sorbent pad consumption can be
reduced from 3,600 pads to 1,800 or 450
if the pads can be reused for two or eight
times, respectively. Correspondingly, the
number of drums for disposal of pads
would be reduced from 24 drums (assum-
ing 150 oil-saturated pads per drum) to
6.5 or 1.6 drums (assuming 275
desaturated pads per drum). The 14 to 16
drums of waste fluids extracted from the
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'bent pads would be processed for re-
3 or hauled away for disposal at a waste-
energy facility.
fhe sorbent pads exhibited enduring
•formance to retain and remove low-
cosity fluids after being compressed re-
atedly through the Extractor™. The sor-
it pads were largely separated and de-
med after two (and no more than three)
raction cycles when used for medium-
Dosity fluids, however. The sorbent pads
iked with high-viscosity fluids did not
ss through the Extractor™ and, there-
fore, would have to be disposed of after
one use.
The recycling of sorbent pads required
no additional health and safety procedures,
except for those described in the manu-
facturers' Material Safety Data Sheets
(MSDS's) for various fluids.
The economic benefits of the roller com-
pression technology were substantial. The
use of the Extractor™ by shops and plants
that handle and/or use various oils and
fluids would result in annual savings of
51% to 75%. The savings come primarily
from the lower disposal costs for spent
pads. Further savings may be possible if
extracted fluids can be recycled. The per
use cost of sorbent pads can be signifi-
cantly reduced from $4.80 for a single use
to $1.19 or less for eight or more reuse
cycles.
The full report was submitted in fulfill-
ment of Contract No. 68-CO-0003, Work
Assignment No. 2-36, by Battelle Memo-
rial Institute under the sponsorship of the
U.S. Environmental Protection Agency.
lie 1. Maximum Practical Pickup And Maximum Effective Pickup
Pad Fluid
ndition viscosity
9S/7 LOW
Iracted Low
ir times
traded Low
Iht
IBS
3S/7 Medium
ish Medium
3sh High
Pad
texture
Unpleated
Un pleated
Unpleated
Unpleated
Pleated
Unpleated
Pad no.
1
2
3
Average
4
5
6
Average
7
8
9
Average
10
11
12
Average
10B
11 B
12B
Average
19
20
21
Average
Fluid
sorbed at
saturation
(9)
346.54
360.28
350.83
352.55
255.95
203.96
195.71
218.54
194.06
195.57
197.65
195. 76
445.65
447.36
452.59
448.53
306.25
292.09
303.41
300.58
444.54
417.91
392. 16
418.20
Time to
"stop"
dripping*
(min)
120
120
120
120
120
120
120
120
>120
>120
>120
>120
>120
>120
>120
>120
>120
>120
>120
>120
120
120
120
120
Maximum
effective
pickupb
(9/9)
5.55
6.57
6.45
6.19
4.51
4.62
5.07
4.73
4.42
4.34
4.45
4.40
11.82
11.18
11.75
11.58
7.78
7.80
7.81
7.80
13.67
13.54
13.68
13.63
Time to
"stop"
dripping' with
fan on(min)
61.0
61.5
62.0
61.5
60.0
60.0
60.0
60.0
60.0
60.0
60.0
60.0
60.0
60.0
60.0
60.0
60.0
60.0
60.0
60.0
60.9
60.9
60.9
60.9
Maximum
effective
pickup0
(9/9)
4.69
5.57
5.37
5.21
3.90
3.75
4.13
3.92
3.58
3.47
3.58
3.54
9.19
8.58
9.36
9.04
6.86
6.96
6.95
6.92
12.14
12.19
12.38
12.24
I t the end of the time recorded, dripping continued at a rate of more than 5 to 15 drops/min.
Maximum Practical Pickup = Fluid sorbed at the end of 2 hr/sorbent pad dry weight.
laximum Effective Pickup = Fluid sorbed at the end of ^ hr with fan on/sorbent pad dry weight
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Table 2. Fluid Pickup by Sorbent Pads
Fluid pickup (%)
Replicate no./pad no.
Fluid
viscosity
Low
Medium0
High
Pad
condition
Fresh
4X'
8X°
Fresh
4X
8X
Fresh
4X
ex
1/28
96.4
93.2
94.2
1/31
97.1
97.5
95.8
1/34
100
N/A
N/A
2/29
98.2
97.2
95.8
2/32
96.2
94.1
93.8
2/35
94.2
N/A
N/A
3/30
98.2
96.2
95.8
3/33
97.5
94.2
99.5
3/36
100
N/A
N/A
Average
97.6
95.5
95.3
96.9
95.3
94.8?
98.1
N/A
N/A
Pad extracted four times.
s, pads were soaked at 50% pad sorting capacity before extractions.
" Based on the performance of Pads No. 3 1 and 32 only.
N/A = Data not available because pad could not pass through Extractor .
4 ~
3 ~
2 ~
1 2
-I 1 1
4
Extraction cycle
10
Figure 3. Cost per use for low-viscosity fluid.
•&U.S. GOVERNMENT PRINTING OFFICE: 1993 - 750-071/80083
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S.C. Chen and R. F. Olfenbuttel are with Battelle Memorial Institute, Columbus,
OH, 43201-2693; At the time of the study, B. T. Cano was a summer student
'ntern at Battelle.
hnny Springer is the EPA Project Officer (see below).
e complete report, entitled "A Fluid Sorbent Recycling Device for Industrial Fluid
Users", (Order No. PB93-218519AS; Cost: $19.50, subject to change) will be
available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
e EPA Project Officer can be contacted at:
Risk Reduction Engineering Laboratory
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
ited States
/ironmental Protection Agency
nterfor Environmental Research Information
icinnati, OH 45268
cial Business
laity for Private Use
10
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
V600/SR-93/154
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