United States
                Environmental Protection
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
                  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).

  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-
  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

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
   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.

  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
   Cost information was  provided by HP
and the AROS manufacturer. Where  pos-
sible, the costs were checked against other

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
  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

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
   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

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
   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
       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
                                 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
Savings ($)
Sewer discharge fees and water costs
Deionized (Dl) water production cost*
Plating wastewater treatment coste*
Purchase of new plating chemicals at
  85% reduction









                                           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

   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
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