United States
Environmental Protection
Agency
Risk Reduction
Engineering Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/SR-93/160 September 1993
i&EPA Project Summary
Recycling Nickel Electroplating
Rinse Waters by Low
Temperature Evaporation and
Reverse Osmosis
Timothy C. Lindsey
Low temperature evaporation and re-
verse osmosis systems were each
evaluated (on a pilot scale) on their
respective ability to process rinse wa-
ter collected from a nickel electroplat-
ing operation. Each system offered ad-
vantages under specific operating con-
ditions. The low temperature evapora-
tion system was best suited to pro-
cessing solutions with relatively high
(greater than 4,000 to 5,000 mg/L) nickel
concentrations. The reverse osmosis
system was best adapted to conditions
where the feed solution had a relatively
low (less than 4,000 to 5,000 mg/L)
nickel concentration. In electroplating
operations where relatively dilute rinse
water solutions must be concentrated
to levels acceptable for replacement in
the plating bath, a combination of the
two technologies might provide the best
process alternative. Initially, the reverse
osmosis system could be used to con-
centrate the feed solution. This could
be followed by low temperature evapo-
ration processing to concentrate the
solution to levels acceptable for re-
placement in the plating bath.
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
This project was a joint effort of Gra-
ham Plating, Chicago, IL, an electroplat-
ing firm; the Hazardous Waste Research
and Information Center (HWRIC), a divi-
sion of the Illinois Department of Energy
and Natural Resources, Champaign, IL;
and the Pollution Prevention Research
Branch of the U.S. Environmental Protec-
tion Agency's Risk Reduction Engineering
Laboratory, Office of Research and De-
velopment, Cincinnati, OH.
Graham Plating is a large "job-shop"
that has been located for many years on
the northwest side of Chicago. A new
modern building has recently been com-
pleted in Arlington Heights, IL, and Gra-
ham Plating currently plans to relocate
the plating operations to the new facility.
This new facility has been designed and
constructed such that special features have
been installed to promote waste reduc-
tion. Large underground rinse water col-
lection tanks have been installed to facili-
tate accumulation, segregation, and stor-
age of rinse waters by principal metal
component. This water can subsequently
be treated through a reverse osmosis sys-
tem, a low temperature evaporation unit,
or both.
This project was performed to evaluate,
compare, and document the effectiveness
of low temperature evaporation and re-
verse osmosis technologies for recovery
and reuse of water and plating bath chemi-
cals associated with electroplating rinse
waters. These technologies were exam-
ined on a pilot scale at the HWRIC pilot
laboratory facility by using actual rinse
water samples collected from a Graham
Plating nickel electroplating line. Economic
assessments conducted for these tech-
nologies assumed that 7,200 gal of nickel
\£) Printed on Recycled Paper
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electroplating rinse water would have to
be processed per day at this facility on a
5-day week and 80% availability basis.
Technology Descriptions
Low temperature evaporators (Licon,
Inc., Pensacola, FL)* heat water under a
vacuum to produce steam at relatively low
* Mention of trade names or commercial products does
not constitute endorsement or recommendation for
use.
temperatures (150 to 160° F). The steam
rises into a condenser where distilled wa-
ter results. The plating bath chemicals do
not rise with the steam and become a
concentrated slurry or solution of chemi-
cals. The evaporation unit is a model C-3,
single effect, pilot-scale evaporator espe-
cially designed for conducting pilot-scale
tests on a variety of feed solutions. Figure
1 provides a schematic of material flow
through a low temperature evaporation
system.
Reverse osmosis is a pressure-driven
membrane separation process in which a
feed stream under pressure (200 to 800
psi) is separated into a purified "perme-
ate" stream and a "concentrate" stream by
selective permeation of solution through a
semi-permeable membrane. The pressure
required to force the permeate through
the membrane is dictated by the osmotic
pressure of the feed stream. Membranes
are constructed of a variety of materials
such as aromatic polyamide, cellulose ac-
etate, and polyether/amide. The reverse
osmosis unit used in this project was an
Osmonics Model PES/OSMO-19T-
80SSXXC reverse osmosis machine for
Cooling
Water
Outlet
Concentrate
Feed/Concentrate (l_J
Steam or Hot Water Qj
Distillate \3j
Cooling Water ^J
Figure 1. Basic flow diagram for single effect evaporator.
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Feed In
permeate
Spacer Membrane Feed Spacer
Figure 2. Components of a spiral-wound membrane.
process evaluation. It was equipped with
one Osmonics Model Number 192T-MSO5
thin-film, composite, spiral-wound mem-
brane cartridge. Figure 2 provides a view
of the components that comprise a spiral
wound membrane. The solution was
prefiltered through a 5 u cartridge filter for
the reverse osmosis testing.
Four, 55-gal drums of nickel electroplat-
ing rinse water were collected from the
Graham Plating facility and processed
through the low temperature evaporation
(Drums A and B) and the reverse osmosis
(Drums C and D) systems. The reverse
osmosis tests were conducted at two dif-
ferent operating pressures: Drum C at
pressures of 250 to 300 psi and Drum D
at 350 to 380 psi. Samples of the concen-
trated feed solution as well as the distil-
late (low temperature evaporation system)
and permeate (reverse osmosis system)
were collected at regular intervals through-
out the tests as the rinse water was pro-
cessed. Nickel analyses were done to de-
termine how efficiently the systems re-
moved nickel from the rinse water and
concentrated it for potential recycling.
Analyses for total organic carbon (TOG)
were done to indicate the fate of organic
constituents (e.g., brighteners) in the rinse
water. Immediately after samples were
collected, electrical conductivity measure-
ments were made to indicate the soluble
salts present in the samples.
Low Temperature Evaporation
System Efficiency
The low temperature evaporation sys-
tem exhibited consistent productivity
throughout the tests. This performance fea-
ture was unfailing regardless of the chemi-
cal concentrations of the feed solution pro-
vided to the system. The evaporation sys-
tem concentrated the rinse water, which
had exhibited initial nickel concentrations
of 2,540 to 4,140 mg/L to nickel levels as
high as 13% to 18%. These levels are
well above the 8% required for placement
into the plating bath. The concentrate, per-
meate, and distillate nickel concentrations
exhibited in samples collected throughout
the tests have been summarized (Table
1). Figure 3 shows how nickel levels
changed in the feed solution during the
course of the low temperature evapora-
tion tests. Nickel concentrations increased
at a steady rate until concentrations of
approximately 25,000 to 30,000 mg/L were
reached. This level corresponds to a point
where approximately 80% to 85% of the
rinse water volume had been processed.
Beyond this point, nickel concentrations
increased dramatically until the final con-
centrations of 13% and 18% were
achieved. The rinse water feed solution
volume was reduced by over 98% as a
result of this process. The evaporation
system concentrated the organic constitu-
ents of the rinse water from initial TOC
levels of 550 to 990 mg/L to final levels of
25,000 to 26,000 mg/L. TOC levels in the
Graham Plating nickle baths are normally
maintained at approximately 14,000 mg/L.
The concentration rate of the organic com-
ponents paralleled the nickel concentra-
tion rate suggesting that little of the or-
ganic material was lost to volatization. As
shown in Table 2, distillate produced by
the low temperature evaporation system
was very low in nickel concentration (av-
erage 0.37 to 0.71 mg/L). Additionally,
TOC concentrations in the distillate were
very low (average 3.04 to 3.50 mg/L).
Disadvantages of the low temperature
evaporation system include its relatively
high ($140,000) capital cost and high en-
ergy requirements ($20/1,000 gal pro-
cessed). The implied rate of return of
10.6% and payback period of 6.9 yr deter-
mined in the economic assessment for
this system suggest that it is a marginal
investment opportunity by today's stan-
dards. These estimates do not, however,
consider the reduced future liabilities
brought about by drastically decreasing
the hazardous waste discharges from the
facility.
Reverse Osmosis System
Efficiency
The feed solution processed through
the reverse osmosis system contained ini-
tial nickel concentrations of 1,425 to 2,580
mg/L (Table 1). Figure 4 depicts how nickel
concentrations in the feed solution
changed as the solutions were processed.
Nickel concentrations increased steadily
until about 60% of the rinse water volume
was processed. At this point, nickel con-
centrations were about 4,000 to 5,000
mg/L in the two drums. Beyond this point,
nickel concentrations increased more rap-
idly until final concentrations of 12,560
mg/L (Drum C) and 17,900 mg/L (Drum
D) were reached. The reverse osmosis
system exhibited superior productivity at
the beginning of the tests, and productiv-
ity dropped off dramatically after about
60% of the feed solution had been pro-
cessed. Beyond these levels, the produc-
tivity of the reverse osmosis equipment
decreased dramatically as solids began to
precipitate and foul the membrane. The
final concentrations achieved with the re-
verse osmosis process were 12,560 to
18,200 mg/L (1.256% to 1.82%) and are
well below the 8% nickel concentration
required for the plating bath. Some of this
solution could be used to replace water
losses in the electroplating process. The
reverse osmosis system, however, would
probably produce excess volumes of con-
centrated rinse water composed of 1.2%
to 1.8% nickel. This material would have
to be further processed with the use of an
alternative technology such as low tem-
perature evaporation or be shipped to a
facility that could extract the nickel for use
in other industrial processes.
The reverse osmosis system concen-
trated the organic constituents present in
the rinse water feed solution from initial
TOC levels of 340 to 540 mg/L to levels of
2,800 to 3,500 mg/L. These concentra-
tions suggest that the organic bath con-
stituents are concentrated by the reverse
osmosis equipment at rates that parallel
the nickel concentration rates.
The quality of the cleaned rinse water
permeate produced by the reverse osmo-
sis equipment was directly related to the
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Table 1. Comparison of Nickel Concentrations in Concentrate, Distillate, and Permeate
Product
Low Temp. Evap. Reverse Osmosis
Drum A Drum B Drum C Drum D
Concentrations at beginning of test (mg/L):
Concentrate 4,140
Distillate 2.5
Permeate —
Concentrations at end of test:
Concen tra te 179,000
Distillate 1
Permeate —
Ratio of distillate permeate to concentrate:
Distillate
Permeate
0.02%
2,540
2.2
128,000
0.3
0.01%
2,580
44.5
12,560
210
1,425
14.5
18,200
790
1.49%
1.54%
200000
100000 -
o Drum A
* Drum B
20
40 60 80
% of Drum Volume Processed
i
100
Figure 3.
Concentrate nickel concentration versus percent of drum volume processed;
low temperature evaporation tests.
quality of the feed solution pumped into
the unit. Permeate produced by the re-
verse osmosis system averaged 89 to 134
mg/L nickel (Table 2). These levels are
about 98.5% lower than the nickel con-
centrations present in the concentrated
solution. This solution would not, how-
ever, be acceptable for discharge to pub-
licly owned treatment works. The nickel
levels present in this solution could be
further reduced by passing this solution
through the reverse osmosis equipment
again. TOG concentrations averaged 19.46
to 21.98 mg/L in the permeate solution
which suggests that some of the organic
compounds were able to permeate the
membrane. The reverse osmosis equip-
ment condensed the feed solution to final
volumes that were 88% to 94% less than
the original volumes of the two tested
drums. Differences between the two tests
can be attributed to the difference in oper-
ating pressures used during the tests.
Advantages of the reverse osmosis sys-
tem include its relatively high production
rates with respect to low concentration
feed solutions. Additionally, it would re-
quire lower capital investment (about
$50,000) than a comparably sized low tem-
perature evaporation system. Energy costs
required to operate a reverse osmosis sys-
tem would be only about $2.50/1,000 gal
processed. Disadvantages associated with
a reverse osmosis system include its in-
ability to concentrate the feed solution to
levels beyond the 12,560 to 18,200 mg/L
levels revealed in this study. This factor
alone would prevent use of a stand-alone
reverse osmosis system at the Graham
Plating facility because of the economic
impracticalities associated with the con-
centrate produced by the system. Another
disadvantage associated with the reverse
osmosis system is the lower quality per-
meate produced by the system. This solu-
tion would probably have to be reused
within the plant or further processed
through the reverse osmosis system be-
fore discharge to the POTW.
Combined Use
Both the low temperature evaporation
and reverse osmosis systems appear to
offer advantages under specific operating
conditions. Based on this factor, the po-
tential for utilizing these technologies in
tandem was examined. The reverse os-
mosis system is best adapted to condi-
tions where the feed solution has a rela-
tively low nickel concentration. It can pro-
cess the low concentration feed solution
with relatively high efficiency to a level of
4,000 to 5,000 mg/L. At this point, the
solution could be transferred to a low tem-
perature evaporator for further concentra-
tion. The low temperature evaporation sys-
tem appears to be best adapted to pro-
cessing solutions with relatively high nickel
concentrations. It can process these solu-
tions so that a concentrate solution com-
posed of 8% or more nickel is produced
along with a very high-quality distillate so-
lution. Using the equipment within its opti-
mum operating ranges would augment the
ability of the systems to process the rinse
water with maximum efficiency while sup-
plying the electroplating operation with
high-quality concentrate, distillate, and per-
meate solutions for reuse. Since the equip-
ment would always be functioning within
optimum concentration ranges, smaller re-
verse osmosis and low temperature evapo-
ration units could be implemented than if
the individual units were used alone. If
this type of combined system were in-
stalled at the Graham Plating facility, it
would require a capital investment of
$115,000, which would be paid back in
2.8 yr through a 27.6% implied rate of
return.
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Electrical Conductivity
Electrical conductivity measurements
taken during operation of both the low
temperature evaporation and reverse os-
mosis systems could be of great value
during actual plant operating conditions.
The electrical conductivity data obtained
in this project were well correlated with
nickel concentration, TOC concentration,
and membrane flux characteristics. Accu-
rate assumptions regarding concentrate,
permeate, and distillate quality could be
based on electrical conductivity measure-
ments taken throughout the work day. Fur-
ther, the equipment could be automated
to accumulate and discharge the various
solutions based on in-process electrical
conductivity measurements that could ac-
tivate pumps, valves, and/or switches when
preset levels were attained.
Additional Research Needs
Additional tests need to be conducted
with rinse water from other electroplating
lines involving other metals. These tests
would aid in determining the usefulness of
these technologies with respect to pro-
cessing the entire spectrum of rinse water
streams that would be produced at a full-
scale electroplating operation. Detailed
analysis of all organic and inorganic rinse
water components (organic brighteners,
sulfate, chloride, etc.) would be useful to
determine the effects of low temperature
evaporation and reverse osmosis process-
ing on the relative quality and quantity of
these constituents. Onsite testing should
be done at an electroplating facility to
allow comparison of full-scale systems with
the pilot-scale tests performed in this study.
This onsite testing would include detailed
study of the performance of the concen-
trated rinse water that is returned to the
plating bath.
The full report was submitted in fulfill-
ment of Contract CR-815829 by Hazard-
ous Waste Research and Information Cen-
ter under the sponsorship of the U.S. En-
vironmental Protection Agency.
Table 2. Average Nickel Concentrations in Distillate and Permeate
Distillate Ni Concentration
Permeate Ni Concentration
A (n=13)
B (n=16)
C (n=22)
D (n=17)
Mean
(mg/L)
0.71
0.37
—
—
Standard
Deviation
(mg/L)
0.63
0.52
-
—
Mean
(mg/L)
—
—
89.55
134.38
Standard
Deviation
(mg/L)
—
49.22
202.19
20000 -i
10000
Drum C
Drum D
20 40 60
% of Drum Volume Processed
80
100
Figure 4. Concentrate nickel concentration versus percent of drum volume processed; reverse osmosis tests.
•&V.S. GOVERNMENT PRINTING OFFICE: H*3 - 750-071/H006I
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Timothy C. Lindsey is with the Hazardous Waste Research and Information
Center, Champaign, IL 61820.
Paul Randall is the EPA Project Officer (see below).
The complete report, entitled "Recycling Nickel Electroplating Rinse Waters by
Low Temperature Evaporation and Reverse Osmosis," (Order No. PB93-
218865; 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
The EPA Project Officer can be contacted at:
Risk Reduction Engineering Laboratory
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/600/SR-93/160
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