United States
Environmental Protection
Agency
Risk Reduction
Engineering Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/SR-93/150 October 1993
EPA Project Summary
Watts Nickel and Rinse Water
Recovery via an Advanced
Reverse Osmosis System
C. Schmidt, I. Erbas-White, and R. Ludwig
The full report summarizes the re-
sults of an 8-mo test program conducted
at the Hewlett-Packard Printed Circuit
Production Plant, Sunnyvale, CA (HP)
to assess the effectiveness of an ad-
vanced reverse osmosis system*
(AROS). The AROS unit, manufactured
by Water Technologies, Inc. (WTI) of
Minneapolis, MM, incorporates mem-
brane materials and system compo-
nents designed to treat metal plating
rinse water and produce two product
streams: (1) a concentrated rnetal solu-
tion suitable for the plating bath, and
(2) rinse water suitable for reuse as
final rinse. Wastewater discharge can
be virtually eliminated and significant
reductions realized in the need for new
plating bath solution and rinse water.
The AROS unit performed very reli-
ably during the test program. During a
5,000-hr trial, approximately 190,000 gal
of rinse water were treated to produce
1,100 gal of concentrated plating bath
for recycle. The second output stream
from the AROS unit was recycled as
clean rinse water, reducing the demand
for deionized water production. In addi-
tion, wastewater treatment and disposal
costs were reduced by approximately
$13,000. If operated at full capacity, the
unit capital cost was estimated to have
a payback period of approximately 2
yrs.
The AROS was evaluated under the
California/EPA Waste Reduction Inno-
'Mention of trade names or commercial products does
not constitute endorsement of recommendation for
vative Technology Evaluation (WRITE)
Program, in which the cooperative ef-
forts of the U.S. Environmental Protec-
tion Agency (EPA) and the California
Environmental Protection Agency were
used to evaluate innovative pollution
prevention techniques.
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 metal plating industry produces large
quantities of metal contaminated waste-
water requiring treatment before discharge.
An AROS manufactured by WTI was in-
stalled in the HP plant in Sunnyvale, CA,
to treat and recover Watts nickel plating
bath solution and rinse water. The tech-
nology approaches zero discharge capa-
bility. An 8-mo test program was conducted
to assess the effectiveness of the AROS
and estimate the incremental cost savings
resulting from less use of deionized water,
reduced wastewater volume being pre-
treated, lower effluent and sludge disposal
quantities, and recovery of plating solu-
tion.
The HP facility manufactures printed cir-
cuit (PC) boards for use in personal com-
puters. In one step of the manufacturing
process, Watts nickel plating is used to
plate a thin layer of conductive material on
a non-conductive surface, like epoxy/plas-
tic or ceramic. Watts nickel is also widely
used in other industries for decorative plat-
Printed on Recycled Paper
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ing operations. The plating operation con-
sists of the following steps:
• Rrst, the PC boards are attached to
moving racks. The moving racks
carrying the parts move through the
Watts nickel solution plating bath
where the nickel plating is
eloctrolytically applied to the PC
boards. When the PC boards are
removed from the bath, plating solution
adheres to them. This adhering
solution is called "dragout."
• Second, the PC boards move
sequentially first through a "dirty" rinse
tank and, second, through a "clean"
rinse tank. The clean rinse water
enters the second "clean" rinse tank
and flows in the opposite direction
from the movement of the PC boards.
In this way, the PC boards encounter
the cleanest rinse water last just before
exiting the second "clean" rinse tank.
This method of having the parts and
the rinse water move in opposite
directions is called countercurrent
rinsing.
Normally, the discharge from the "dirty"
rinse tank is wastewater to be treated and
discharged. The ARCS unit, however,
treats this wastewater to separate out the
metal compounds. This separation creates
two product streams: a stream of deion-
ized water called the permeate and a liq-
uid stream of concentrated metal com-
pounds called the concentrate. Both of
these product streams are reused in the
production process. The permeate stream
is returned to the "clean" water rinse tank.
The concentrate stream of metal com-
pounds is returned to the plating bath.
This recycling eliminates the need for nor-
mal wastewater discharge. In addition, the
AROS unit greatly reduces the volume of
new deionized makeup water needed for
the rinse tank and generates concentrated
Watts nickel solution that can be recycled
to the plating bath.
The heart of the AROS unit is a special-
ized reverse osmosis unit. Reverse osmo-
sis is a physical process in which water
containing dissolved materials can be sepa-
rated from those dissolved materials. Pres-
sure is applied to the solution on one side
of a membrane barrier. Water passes
through the membrane, but dissolved metal
tans remain behind, thus becoming more
concentrated. The membranes are made
of polyamide, thin-film plastics that can
perform well under a wide range of pH
conditions (1 to 13.5) and high pressures
(400 to 1100 psi) as needed to reconcen-
trate a wide range of dilute rinse waters to
produce recycled plating bath solutions.
In addition to the reverse osmosis mem-
brane, the AROS unit contains pumps,
valves, interim solution holding tanks, sen-
sors, and piping needed to manage the
flows into and out of the membrane unit.
The operation is automatically controlled
by a computer program that monitors flow
quality (using conductivity), flow volumes,
and other operating parameters. The unit
is enclosed in a lidded box about 3 ft high
by 4 ft wide by 8 ft long. The plumbing and
electrical and communications connections
are relatively simple.
The objectives of the study were to (1)
evaluate the AROS unit performance and
reliability, (2) assess the quality of the re-
cycled plating bath solution and the re-
cycled rinse water, and (3) analyze costs
and benefits.
Procedure
The test program was conducted by HP
with assistance from the AROS manufac-
turer. The program included continuous
monitoring of flow volume, conductivity, and
pH at various monitoring points in the sys-
tem. Streams monitored include the deion-
ized rinse water makeup line, the concen-
trate return line, and the permeate return
line. The plating bath was sampled and
analyzed weekly. Analyses were conducted
for nickel, pH, Nickel PC-3 (Saccharin),
boric acid, chloride, and ductility.
Independent sampling and analysis were
performed by the EPA contractor over a 1 -
day period to verify results reported by
HP.
Cost information was provided by HP
and the AROS manufacturer. Where pos-
sible, the costs were checked against other
sources.
Results and Discussion
The AROS unit achieved excellent sepa-
ration of contaminants from the influent
dirty rinse water. Removals of. contami-
nants usually ranged from 95% to 97%.
Overall the HP staff regard the AROS unit
as having shown good performance dur-
ing the test period. Rinse water quality
was maintained at a low level of nickel
contamination. It was reported that no
printed circuit boards were rejected be-
cause of Watts nickel plating deficiencies.
The recycling of the rinse water resulted in
a dramatic 98% reduction in the use of
new deionized water makeup for this plat-
ing process, equivalent to about 425,000
gal annually per shift per plating line.
The AROS unit also successfully pro-
duced concentrated Watts nickel solution
of adequate quality to return to the plating
bath solution. Fresh Watts nickel solution
costs about $5.00/gal, so recovery and
recycling represented a significant direct
savings. It was also calculated that ap-
proximately 3 tons of category F006 sludge
was not generated by the industrial waste
water treatment system that otherwise
would have been without use of the AROS
unit.
The AROS unit demonstrated excellent
reliability during most of the test period.
For example, during the period February
28 through June 29,1990, the system was
on-line 3,594 hrs and experienced a down-
time of only 20 hrs. Mechanical failures
experienced in July and August1990, how-
ever, caused over 200 hrs of downtime
during these months. The manufacturer is
reported to have made design changes
that will prevent similar future mechanical
failures.
Economic Analysis
Cost information provided by HP (see
Table 1) indicated that the AROS unit would
produce an estimated annual cost savings
of $26,250 at the HP facility using the unit
at less than half its rated hydraulic capac-
ity. This savings is reduced by an esti-
mated annual operating and maintenance
cost of $9,419 for a net annual savings of
approximately $17,100/yr. Capital invest-
ment is approximately $75,000, which rep-
resents approximately $63,000 for the
AROS unit plus another $12,000 for mak-
ing the installation permanent and for train-
ing of operating personnel. Dividing
$75,000 by $17,100 results in a payback
period of 4.4 yrs and a 23% return on
investment.
The AROS unit at HP was operated at
less than 50% of its capacity. The eco-
nomic benefits would havs been more fa-
vorable if the Watts nickel plating process
had been operating for more hours and
producing more printed circuit boards. The
AROS unit volumetric design capacity for
influent rinse water is over twice the vol-
ume of rinse water processed at HP
Another economic factor is that at HP
the AROS unit treated only a small frac-
tion, e.g., about 3%, of the total wastewa-
ter flow. Therefore, in its cost analysis HP
made no allowance for reduced labor cost
at its main wastewater pretreatment plant.
At another facility, however, the AROS
unit treated a larger percentage of the
total wastewater flow, a labor reduction
credit might have been included in the
cost analysis.
Finally, the HP facility has a fully amor-
tized wastewater treatment facility in place.
Elsewhere at a new facility under design,
it could be feasible to reduce the capacity
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and capital cost of the wastewater treat-
ment facility because the inclusion of an
AROS unit would reduce design flow vol-
ume. In addition, it would be possible to
reduce the capacity of the deionized wa-
ter production units. Economic cost-ben-
efit analysis will be different for each po-
tential application of an AROS-type unit
depending upon the site specific situation.
Conclusions and
Recommendations
• Overall the AROS unit performed very
well during the test program. Recovery
and recycling of plating bath solution
and deionized rinse water was
routinely successful and no loss of
plating quality occurred.
Significant cost savings resulted from
reduced use of deionized water,
reduced wastewater volume being
pretreated, less effluent and sludge
disposal, and recovery of plating
solution.
Payback period and return on
investment will vary depending on site-
specific conditions. If the AROS unit
was operating near capacity at HP,
the payback period is estimated at
about 2 yrs. This demonstration
indicates that there are many situations
where the unit should be considered
for its economic benefits as well as its
environmental waste minimization
advantages.
The full report was submitted in fulfill-
ment of Contract 68-C8-0062, WA 3-18,
by Science Applications International Cor-
poration under the sponsorship of the U.S.
Environmental Protection Agency.
Table 1. Estimated AnnualIncrementalSavings from Use of the AROS Unit as Reported by Hewlett-
Packard Company, 1990 Costs
Description of Costs
Estimated
Savings
($/gal)
Quantity
(gal)
Total
Annual
Savings ($)
Sewer discharge fees and water costs
Deionized (Dl) water production cost*
Plating wastewater treatment coste*
Purchase of new plating chemicals at
85% reduction
0.004
0.0064
0.0062
5.00
1,275,000
1,275,000
1,275,000
1260x
0.85
5,100
8,160
7,905
5,355
Total estimated annual savings $26,520
*DI water production cost is for chemicals, electricity, and resin replacement only. No labor, deprecia-
tion, or other costs are included because it is assumed that they would remain the same whether the
AROS unit was used or not.
+ Plating wastewater treatment cost includes sludge disposal, chemicals, and electricity. As in the note
above, no labor, depreciation, orothercosts are included because itisassumedthattheywouldremain
the same whether the AROS unit was used or not.
6 U.S. GOVERNMENT PRINTING OFFICE: 1993 - 750-071/80073
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C. Schmidt and I. Erbas-White are with Science Applications International
Corp., Santa Ana, CA 92705, and R. Ludwig is with the California Environ-
mental Protection Agency, Sacramento, CA 95812-0806.
Lisa M. Brown Is the EPA Project Officer (see below).
The complete report, entitled "Watts Nickel and Rinse Water Recovery via an
Advanced Reverse Osmosis System," (Order No. PB93-229 011'/AS; 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, 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-93/150
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