&EPA
            United States
            Environmental Protection
            Agency
            Industrial Environmental Research
            Laboratory
            Cincinnati OH 45268
EPA-600/2-80-084
May 1980
            Research and Development
Evaluation of
Reverse Osmosis
Membranes for
Treatment of
Electroplating
Rinsewater

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                RESEARCH REPORTING SERIES

Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Eliminatijpn of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:             |
      1.
      2.
      3.
      4.
      5.
      6.
      7.
      8.
      9.
Environmental Health Effects Research
Environmental Protectiop Technology
Ecological Research
Environmental Monitor!
Socioeconomic Environmental Studies
Scientific and Technical! Assessment Reports (STAR)
Interagency Energy-Environment Research and Development
"Special" Reports     ;
Miscellaneous Reports
ng
This report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution-sources to meet environmental quality standards.
 This document is available to the public through the National Technical Informa-
 tion Service, Springfield, Virginia1 22161.

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                                            EPA-600/2-80-084
                                            May 1980
EVALUATION OF REVERSE OSMOSIS MEMBRANES FOR
  TREATMENT OF ELECTROPLATING RINSEWATER
                     by

            Kenneth J. McNulty
              Peter R. Hoover
      Walden Division of Abcor, Inc.
     Wilmington, Massachusetts 01887
                    for
 The American Electroplaters1 Society, Inc.
        Winter Park, Florida 32789
             Grant No. R804311
              Project Officer

              Mary K. Stinson
   Industrial Pollution Control Division
 Industrial  Environmental Research Laboratory
          Edison, New Jersey 08817
 INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
     OFFICE OF RESEARCH AND DEVELOPMENT
    U.S. ENVIRONMENTAL PROTECTION AGENCY
           CINCINNATI,. OHIO 45268

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                                 DISCLAIMER
     This report has been reviewed by the Industrial Environmental Research
Laboratory - Cincinnati, U.S. Environmental  Protection Agency, and approved
for publication.  Approval does not signify that the contents necessarily
reflect the views and policies of the U.S. Environmental Protection Agency,
nor does mention of trade names or commercial products constitute endorsement
or recommendation for use.
                                     ii

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                                   FOREWORD
     When energy and material resources are extracted, processed, converted,
and used, the related pollutional impacts on our environment and even on our
health often require that new and increasingly more efficient pollution
control methods be used.  The Industrial Environmental Research Laboratory -
Cincinnati (IERL) assists in developing and demonstrating new and improved
methodologies thatjwill meet these needs both efficiently and economically.

     This report is a product of the above efforts.  It was undertaken to
demonstrate the effectiveness and economic feasibility of using reverse
osmosis for closed-loop control of metal finishing rinse wastes under actual
plant conditions.  The reverse, osmosis system concentrates the chemicals for
return to the processing bath while purifying the wastewater for reuse in the
rinsing operation.  The results of the report are of value to R&D programs
concerned with the treatment of wastewaters from various metal finishing,
non-ferrous metal, steel, inorganic and other industries.  Further information
concerning the subject can be obtained by contacting the Metals and Inorganic
Chemicals Branch of the Industrial Pollution Control Division.
                                                David 6. Stephan
                                                    Di rector
                                 Industrial Environmental Research Laboratory
                                                  Cincinnati

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able reverse osmosis membranes can
to define the applicability of new
                                  ABSTRACT
     Because of the limited pH range in which current commercially avai.l-
be applied, a test program was initiated
membrane materials to the treatment of
rinsewaters with extreme pH levels and high oxidant levels (chromic acid).
Life tests were conducted with the PA-300, PBIL, NS-100, NS-200, SPPO, B-9,
and CA membranes on rinsewater from copper cyanide, zinc cyanide, acid
copper, and chromic acid plating baths.  The PA-300 membrane exhibited
superior performance for the treatment of copper cyanide, zinc cyanide, and
chromic acid rinsewaters, and further development and demonstration of this
membrane is recommended.  The NS-200 and PBIL membranes exhibited the best
performance for treatment of acid popper rinsewaters.  Efforts are underway
to commercialize all three of the Selected membranes (PA-300, NS-200, and
PBIL).                            !

     This report was submitteH in fulfillment of EPA Grant Number
R804311 by the American Electroplaters' Society, Inc. (AES) under the partial
sponsorship of the U.S. Environmental Protection Agency.  This report covers
the period March 1, 1976 to October 19, 1977,  and work  was  completed  as  of
June 12, 1978.

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                                  CONTENTS
Foreword ......
Abstract 	
Figures .......
Tables	
Acknowledgment
     2.
     3.
     4.
     5.
     6.

References
Introduction 	,
Conclusions 	,
Recommendations	,
Background 	,
Experimental Procedures,
Results and Discussion ,
 m
  iv
  vi
 yii
vi i i

   1
   2
   3
   4
   9
  17

  30
Appendix:  Complete membrane-performance data .			   31

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                                   FIGURES

Number                                                                Page

  1  Membrane module configurations	   5
                                 t
  2  Simplified flow schematic of test system ,		  13
                                    vi

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                                    TABLES

Number                                                                      Page

  1  Advantages and Limitations of RO 	  7

  2  Membrane Materials and Configurations Tested 	-	 10

  3  Composition of Plating Baths Tested	 11

  4  Concentration Ranges of  Constituents in Test
        Solutions	 12

  5  Membrane Flux and Conductivity Rejection Values Obtained
       Under Standard Conditions Prior to Exposure to 5% and
       25% Plating Bath Dilutions	 15
  6  Chemical Analyses 	 16

  7  Membrane Performance During Life Test With Copper Cyanide
       Rinsewater at 5% of Bath Strength (pH = 10-13)	 18

  8  Membrane Performance During Life Test With Copper Cyanide
       Rinsewater at 25% of Bath Strength (pH = 11-13)	 20

  9  Membrane Performance During Life Test With Zinc Cyanide
       Rinsewater at 5% of Bath Strength (pH = 12-13)	 22

 10  Membrane Performance During Life Test With Zinc Cyanide
       Rfnsewater at 25% of Bath Strength (pH >13) 	 23

 11  Membrane Performance During Life Test With Acid Copper
       Rinsewater at 5% of Bath Strength (pH = 1.2)  	;	 24

 12  Membrane Performance During Life Test With Acid Copper
       Rinsewater at 25% of Bath Strength (pH = 0.6-0.9) 	 26

 13  Membrane Performance During Life Test With Chromic Acid
       Rtnsewater at 5% of Bath Strength (pH = 1.3-1.7) 	 27

 14  Membrane Performance During Life Test With Chromic Acid
       Rinsewater at 25% of Bath Strength (pH = 1.1-1.2) 	 29
                                      vtt

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                              ACKNOWLEDGMENT
                                   i
                                   i

     The authors gratefully acknowledge the financial  support of EPA (Grant
No. R804311) and AES (Research Project No. 39) for this program.  Technical
support for this program was received from the EPA Project Officer, Ms.  Mary
Stinson, and from the AES Project Committee:  Messrs.  Jack Hyner, Joseph
Conoby, Charles Levy, Herbert Rondeau, James Morse, and George Scott.

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                                  SECTION 1

                                INTRODUCTION
     Since enactment of the Federal Water Quality Control Act and its amend-
ments, the metal finishing industry has become increasingly concerned with
techniques for wastewater treatment.  A variety of new technologies have
been developed for the treatment of electroplating wastewaters; however, none
of these technologies appears to offer an optimum solution to all aspects of
the problem.  As a result, many platers are waiting for further development
and demonstration of new technologies before attempting to make final
decisions on the selection of wastewater treatment processes.

     Wastewater treatment technologies for the electroplating industry can be
broadly classified as end-of-pipe destruction processes or in-plant recovery
processes.  The end-of-pipe destruction processes treat a total shop effluent
to remove a mixture of heavy metals.  At present it is neither technically
nor economically feasible to recover and recycle metals from  end-of-pipe
processes (1).  On the other hand, in-plant recovery processes treat rinse-
water from a specific plating bath (or other operation), making it possible
to recover and return the heavy metals to the plating bath.

     It seems reasonable to speculate that most, if not all, plating shops
will require an end-of-pipe treatment process, particularly for diversified
job shops where in-plant recovery of all  rinsewaters is neither technically
nor economically feasible.  Even for less diversified shops, end-of-pipe
treatment would be required for spills, contaminated plating baths, spent
cleaners, etc.  However, because of the inherent disadvantages of end-of-
pipe treatment -- loss of valuable plating chemicals, cost of sludge dis-
posal, and cost of treatment chemicals -- it is also reasonable to speculate
that platers will use in-plant recovery processes where the economics for
recovery are favorable or where recovery could reduce the load on the end-
of-pipe system to the extent necessary to meet the discharge regulations for
specific contaminants.

     Aside from a few applications in which closed-loop recovery can be
achieved by countercurrent rinsing alone, some technique must be used to
separate the dissolved plating chemicals  from the rinsewater.  The leading
techniques for making this separation are reverse osmosis (RO), evaporation,
and ion exchange.  This report addresses the application of reverse, osmosis
to the recovery of electroplating rinsewaters,  particularly extreme pH
rinsewaters.

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                                 SECTION 2

                                CONCLUSIONS
     On the basis of life test results for various membranes (NS-100,  NS-200,
PA-3QO, PBIL, SPPO, B-9, and CA) with different electroplating rinsewaters
(copper cyanide, zinc cyanide, acid copper, and chromic acid), it is conclu-
ded that PA-300 is the most generally applicable of the membranes tested for
treatment of rinsewaters with extreme pH levels or high levels of oxidants
(chromic acid).  The PA-300 membrane was superior to the other membranes for
treatment of copper cyanide, zinc cyanide, and chromic acid rinsewaters.
However, the NS-200 and PBIL membranes proved to be better than PA-300 for
the treatment of acid copper rinsewaters.

     Of these three membranes, PA-300 is the closest to commercialization.
A full-scale, spiral-wound module containing the PA-300 membrane has been
developed and extensively tested by [the Fluid Systems Division of UOP  for
brackish-water and seawater desalting.  Although the module has not yet been
officially commercialized, modules are being fabricated and supplied on a
special-order basts.
     The NS-200 membrane is being actively developed toward commercialization
by the Fabric Research Laboratory.  JAt present, hollow-fiber modules with  an
output of 380-1140 liters (100-300 gallons) per day (approximately one-tenth
the output of a full-scale module) are being fabricated for testing on sea-
water desalination and various wastewater streams.  The manufacturer
anticipates commercialization within one year.

     The PBIL membrane is being developed by the Maiden Division of Abcor,
Inc. under contract to the Office of Water Research and Technology.   Membrane
casting procedures have been optimized, and a program has been recently
tntttated to develop procedures for [fabricating the PBIL membrane in a spiral-
wound configuration.

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                                 SECTION 3

                              RECOMMENDATIONS
     Additional testing and development work is required before the promising
membranes identified during this program can be offered to electroplaters as
a viable means of achieving closed-loop recovery of rinsewaters.  Future tests
should be conducted with full-scale membrane modules in order to determine
the stability of both membrane and non-membrane components (such as adhesives)
and to determine membrane performance under realistic hydrodynamic conditions.
Future tests should also be conducted on-site under closed-loop conditions
in order to expose the membranes to the same rinsewater as in actual
operation.  Therefore,it is recommended that a full-scale RO system, with
sufficient flexibility to test various new membrane modules, be designed and
operated at an electroplating facility in order to demonstrate closed-loop
RO recovery of difficult-to-treat rinsewaters.  For the immediate future,
tt is recommended that field tests be conducted with the PA-300 spiral-wound
module to determine its suitability for recovery of zinc cyanide rinsewaters.
It is also recommended that membrane manufacturers be encouraged to develop
new membranes and improved membrane modules that will withstand the severe
conditions of electroplating applications.

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                                 SECTION 4
                                  [
                                BACKGROUND
PRINCIPLES OF REVERSE OSMOSIS     i

     Reverse osmosis is a pressure-driven membrane separation process in
which a feed stream under pressure: (27.2-54.4 atm [400-800 psig])  is
separated into a purified "permeate" stream and a "concentrate" stream by
selective permeation of water through a semi-permeable membrane.   There are
three major types of commercially available membrane modules:  tubular,
spiral-wound and hollow-fiber.  These are shown in Figure 1.   Each of these
modules has particular advantages and limitations.  Tubular modules are not
susceptible to plugging by suspended solids and can be operated at high
pressures, but their space requirement (m3 per m2 membrane surface) is
relatively high and their cost is Approximately five times as high as the
other configurations for an equivalent rate of permeate production.
Therefore,tubular modules are not recommended for plating applications.

     Spiral-wound and hollow-fiber! modules are essentially identical in cost
for an equivalent rate of permeate! production.  Hollow-fiber modules have a
somewhat lower space requirement pbr unit of permeate produced, while the
spiral-wound modules are less susceptible to plugging by suspended solids.
                                  !
     There are a number of membranb materials presently under development,
but only two types are currently in commercial use.  The most widely applied
is cellulose acetate (or cellulose' tri-acetate), which was originally devel-
oped for water desalination and has since been adopted for many industrial
waste treatment applications.  It jis available in tubular, spiral-wound,  and
hollow-fiber configurations and exhibits excellent water permeation rates
and high rejection of ionic species.  Unfortunately, it is limited to a
fairly narrow pH range (2.5-7).  Operation beyond this range hydrolyzes the
membrane and destroys its ability to pass.water selectively.
                                  i
     The other commercially available membrane is duPont's polyamide membrane
which is presently available only Jin a hollow-fiber configuration.  It also
exhibits high flux and high rejection, but can be applied over a somewhat
broader pH range (4-11).

     In general the cellulose acetate membrane should be used at low pH,  and
the polyamide membrane at high pH.i  In the region of pH overlap, neither
membrane has an overriding advantage.

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                          Casing^
                               a.   Tubular Membrane
                                        FEED FLOW
PERMEATE SIDE BACKING    -  X
MATERIAL WITH MEMBRANE ON^
EACH SIDE AND GLUED AROUND
EDGES AND TO CENTER TUBE      \
                  FEED SPACER


                          MEMBRANE

b.  Spiral-Wound Module
                                                                    PERMEATE SPACER
                                                                            PERMEATE TUBE
                                           GLUE LINE
                  CONCENTRATE
          SNAP RING    OUTLET
FLOW SCREEN
                                      EPOXY
                          OPEN ENDS    TMRC CUCCT
                          OF FIBERS    TUBE ?HEET
                                           POROUS
                                         BACK-UP DISC
     •0' RING SEAL
      FEED
                                                                         SNAP RING
                                                                           PERMEATE
          END PLATE
                           FIBER
                        •0' RING SEAL
               POROUS FEED          END PLATE
             DISTRIBUTOR TUBE
                            c.  Hollow-Fiber  Module
                  Figure 1.  Membrane module configurations.

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Membrane  performance  is  characterized  in terms of flux and rejection.  Flux
is  the  rate  at which  purified water permeates through the membrane per unit
area of membrane  surface and is given  in liters per square meter per hour
(l/m2-hr).   Rejection is the degree to which salts are prevented from
passing through the membrane and is given by:
% Rejection =
                                 x 100%
where:    Cp = concentration in fe|ed stream

          C  = concentration in permeate stream.

In general both flux and rejection increase with operating pressure and
decrease with increasing feed concentration.  Flux increases with
temperature, but rejection is essentially temperature-independent.  The flow
rate of feed tangential to the membrane surface is also an important
parameter and must be maintained at a high enough level to prevent the
buildup of rejected salts at the membrane surface.

     The major advantages and limitations of reverse osmosis are listed in
Table 1.  The objective of the research effort described below was to
identify new membrane materials that would broaden the allowable pH range
(Limitation #1) and would reduce t|he required frequency of membrane replace-
ment (Limitation #4).             i

APPLICATION OF COMMERCIALLY AVAILABLE MEMBRANES TO RINSEWATER RECOVERY
                                  i
     Because of the potential  cost[advantage of RO relative to other recovery
processes, EPA and AES have sponsored a number of projects  aimed at develop-
ing and demonstrating RO for the treatment of electroplating rinsewaters.
Work performed under EPA Grant R803753 (AES Project 32) included both in-
house and field tests of commercially available membranes  (2,3).   The in-
house tests were conducted with samples of actual  plating  baths diluted to
Varfous- concentrations to simulate actual  rinsewater.    Nine diff-
erent plating-bath rinsewaters were treated with the two commercially avail-
able membranes (cellulose acetate and polyamide) in full-scale RO modules.
                                  1
     It was concluded from these tests that RO appeared promising for the
treatment of nickel baths (Watts, sulfamate, fluoborate) and copper
pyrophosphate.  Treatment of relatively low-pH cyanide baths also appeared
feasible with the polyamide membrane.  However, the commercially available
membranes did not appear to have a suitable operating life for the treat-
ment of highly oxidizing rinsewaters (chromic acid), low pH (<2) rinsewaters,
and high pH (>11) rinsewaters.    [

     Following in-house testing, various field tests were conducted to
demonstrate the performance of RO under realistic conditions.  The polyamide
membrane in hollow-fiber configuration was successfully demonstrated for the
treatment of Watts nickel rinsewaters (4).  (The cellulose acetate membrane
in spiral-wound configuration has also been successfully demonstrated on
Watts nickel rinsewater [5]).   it was concluded that either of the two
commercially available membranes c$n be used to treat nickel  rinsewaters and

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               TABLE 1.  ADVANTAGES AND LIMITATIONS OF RO
ADVANTAGES

  1.  Low capital cost.  The modular nature of RO units makes them
      particularly well-suited for small-scale installations.

  2.  Low energy cost.  Only power for pumping is required;  there
      is no phase change as in evaporation.

  3.  Low labor cost.  The process is fully automated and simple
      to operate,requiring little operator attention.

  4.  Low space requirements.  Since RO equipment is compact and
      operates continuously, it requires minimal  tankage.
LIMITATIONS

  1.  There is a limited pH range (about 2.5 - 11)  over which  current
      commercially available membranes can operate  for extended
      periods.

  2.  RO is incapable of concentrating solutions  to very high
      concentrations.  For ambient temperature baths,a small
      evaporator is generally required to close the loop.

  3.  Certain species, e.g., small  non-ionized molecules,  are  not
      completely rejected by the membrane.

  4.  Membrane performance generally degrades with  time,requiring
      periodic replacement of the membrane modules.

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that the economics for closed-loop nickel recovery can be quite attractive.
This has been proven in industrial practice:  approximately 100 RO systems
have been sold for the treatment of[nickel rinsewaters.
                                   r

     In an effort to expand the application of RO to major plating baths
other than nickel, two separate fiel|d demonstrations were conducted on
copper cyanide rinsewaters with the-polyamide membrane (6).  In general, it
was concluded that the polyamide membrane can be used for the recovery of
relatively low-pH cyanide rinsewaters, provided that the membrane life is
adequate.  However, since rapid membrane deterioration was observed in one
of the two field tests, the treatment of copper cyanide rinsewaters cannot
be considered a proven application.,
                                   i
     From these results as well as the known pH tolerance of the
commercially available membranes, it became evident that new membranes must
be developed in order to expand the'applicability of RQ to major plating
baths other than nickel.  In particular, membranes must be developed with
resistance to pH extremes (<2 and >11) and with resistance to oxidants
(chromic acid). The current program;(EPA Grant R804311; AES Project 39) was
undertaken to identify promising new membranes for electroplating applicati-
ons.
                                      8

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                                 SECTION 5

                          EXPERIMENTAL PROCEDURES
MATERIALS AND METHODS

     Table 2 lists the membranes investigated during this program along with
the manufacturer from which the membrane was obtained and a brief descrip-
tion of the membrane configuration and materials.  Membranes other than those
listed are under development but, for a variety of reasons, were not sub-
mitted by the manufacturer for testing during this program.  In addition to
the new membrane materials, the two commercially available membrane types,
B-? (polyamide) and CA (cellulose acetate) were tested in order to provide
a reference level to which the new membranes could be compared.  The B-9
membrane (pH range 4-11) was the reference for alkaline rinsewaters, and the
CA membrane (pH range 2.5-7) was the reference for acid rinsewaters.

     Table 3 lists the plating baths used to prepare the rinsewaters tested
in this program.  The major components and nominal composition are also
listed for each plating bath.  These baths were selected because of their
extreme pH levels and, in the case of chromic acid, high oxidation potential.,
Rinsewaters were prepared from each bath of Table 3 by dilution to the
appropriate concentration.  Life tests were conducted at two dilutions for
each bath:  5% of bath strength and 25% of bath strength.  The dilutions
were performed on a volumetric basis, e.g., one liter of bath per three
liters of water for the 25% dilution.  From actual feed analyses
conducted during the life tests, the concentration ranges for the constitu-
ents of interest were determined for each dilution and are listed in Table 4.

TEST SYSTEM

     A simplified flow schematic of the test system is shown in Figure 2.
Feed was withdrawn from the feed tank by a centrifugal booster pump and
passed through two cartridge filters in series.  A high-pressure diaphragm
pump was used to pressurize the feed and pass it through the membrane test
cells.  The pressures within the cells were controlled in the range of
27.2-54.4 atm (400-800 psi) with back-pressure regulators.  An accumulator
was used to dampen pressure pulsations from the high-pressure pump; a
pressure relief valve and high-pressure switch were used to prevent over-
pressurization of the membranes; and a low-pressure switch was used to
prevent the pumps from running dry.  A cooling coil with automatic temper-
ature control  was used to maintain the feed at a constant temperature, and
the surface of the feed tank was covered with polyethylene balls to prevent
evaporation and C02 absorption (by alkaline solutions).

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             TABLE 2.  MEMBRANE MATERIALS AND CONFIGURATIONS TESTED
Membrane
material
Source
Description
PA-30Q       Fluid Systems Div.
             of UOP, Inc.
             San Diego, CA

PBIL         Wai den Div. of
             Abcor, Inc.
             Wilmington, MA

NS-100       Wai den Div. of
             Abcor, Inc.
             Wilmington, MA
NS-200       Fabric Research Lab.
             Dedham, MA
NS-200       Wai den Div. of
             Abcor, Inc.
             Wilmington, MA

SPPO         General Electric Co.
             Wilmington, MA

B-9          E.I. duPont
             Wilmington, DE
CA           Abcor, Inc.
             Wilmington, MA
                   Flat-sheet composite membrane  of poly
                   (ether/amide)  on polysulfone.
                   Flat-sheet asymmetric membrane  of
                   polybenzimidazolone.


                   1/2-inch tubular composite membrane
                   of polyethyleneimine  cross-linked
                   with tolylenediisocyanate on poly-
                   sulfone.

                   0.006-inch ID hollow-fiber composite
                   membrane of polyfurfuryl  alcohol  on
                   polysulfone.  Modules supplied.

                   1/2-inch tubular composite membrane
                   of polyfurfuryl  alcohol  on poly-
                   sul fone.

                   Flat-sheet sulfonated polyphenylene-
                   oxi de.

                   Hollow-fine-fiber asymmetric membrane
                   of aromatic polyamide.  Mini-permeator
                   supplied.

                   1/2-inch tubular membrane of asymmetric
                   cellulose acetate.
                                      10

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              TABLE  3.  COMPOSITION OF  PLATING  BATHS  TESTED
  Plating bath/
    supplier
          Component
      Nominal
    composition
Chromic acid
Udylite
Acid copper
Lea-Ronal
Copper cyanide-1
MacDermid
Copper cyanide-2
R.O. Hull
Zinc cyanide
R.O. Hull
Chromic acid
Sulfate
Catalyst (fluoride)

Copper sulfate
Sulfuric acid
Brightener (Copper Gleem PC)
Chloride

Copper as metal
Free cyanide (as KCN)
Potassium hydroxide
Rochelle salt (Roche!tex)
Brightener (CI Bright Copper)
(Potassium carbonate)

Copper as metal
Free cyanide (as NaCN)
Caustic
Rochellesalt (Roplex)
Brightener

Zinc as metal
Free cyanide (as NaCN)
Caustic
Brightener (ROHCO 532)
255 gm/1
0.90 gm/1
Unknown

60-90 gm/1
172-219 ml/I
0.4-0.6% vol
50 ppm

47 gm/1
20 gm/1
15 gm/1
6% by vol.
0.2% by vol.
(37 gm/1  )

28 gm/1
8.8 gm/1
8.8 gm/1
2-4% by vol.
none

18-22 gm/1
37-52 gm/1
82-97 gm/1
2.3 ml/1
                                   11

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OPERATING PRESSURE

     The test system was operated in a total recycle mode with both composite
and permeate returned to the feed liank.  This mode of operation permits
continuous long-term operation with only a relatively small volume of
feed.  In general, the membranes were tested at a temperature of 25°C and
at the pressures and feed flow rates listed below:
      Membrane

PA-3QO
PBIL
NS-100
NS-200 (hollow-fiber)
NS-200 (tubular)
SPPO
B-9
CA
Operating pressure, atm

         54 A
         54 J4
         40 J8
         54 J4
         40 J8
         40 j 8
         27 J 2
         40 la
Feed circulation rate,  1pm

           1.1
           1.1
           1.9
           1.9
           1.9
           0.19*
           0.19
           1.9
Membrane performance was determined by measuring the flux and rejection for
each membrane as a function of operating time.  The flux was determined by
measuring the permeate flow rate (graduate and stopwatch technique) for each
membrane, and the rejection was determined by obtaining samples of the feed
and the permeate from each membrane and analyzing for various bath con-
stituents.                         '

     Tests were conducted with the four plating bath types for a total of
1000 hours each — 500 hours at 5% \of bath strength and 500 hours at 25%
of bath strength.  Prior to each 500-hour life test the membranes were
evaluated for flux and rejection characteristics under standard conditions
using sodium chloride feed solution (see Table 5).  The salt rejections of
the fresh membranes selected for testing always fell within the range of
80-99%.  However, several of the membranes that were previously exposed to
plating bath solutions exhibited rejections of less than 80%; these
membranes were used in subsequent life tests only because new replacement
membranes were not readily available.
                                   j
ANALYSES

     The methods of analysis used are listed in Table 6.
  Additional turbulence was promoted in the SPPO test cell by a
  magnetic stirrer.                j
                                     14

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-------
                           TABLE 6,  CHEMICAL ANALYSES
Constituent
Conductivity
Copper
Free cyanide
Hexavalent chrome
Zinc
Sulfate
       1  Method
       i   -- - 	
Conductivity meter
Atomic absorption
Specific ion electrode
       1
Colorimetric
Atomic absorption
Turbidimetric
Procedure number
       205*
       301 A*
  Orion Manual
       307B*
       301 A*
       427C*
*From "Standard Methods for the Examination of Water and Waste Water,"
 APHA, 14th Ed., 1975.            !
                                    16

-------
                                  SECTION 6

                            RESULTS AND DISCUSSION


     Results are presented below for all  the plating bath rinsewaters in the
order in which they were tested:  copper cyanide, zinc cyanide, acid copper,
and chromic acid.  For clarity, only 'those data obtained at the start, mid-
point, and end of each test are shown here*; complete membrane performance
data are presented in the Appendix.

COPPER CYANIDE

     Copper cyanide was the first plating bath to be tested, and during the
initial tests the PA-300 and PBIL membranes were not yet available.   There-
fore the NS-100, NS-200, SPPO, and B-9 membranes were tested with the
copper cyanide-1 bath listed in Table 3.  The PA-300 and PBIL membranes were
tested at a later time with the copper cyanide-2 bath listed in Table 3.
These baths are reasonably similar in composition, which should permit a
direct comparison of the results for all  the membranes.

     Table 7 gives the results for tests conducted with rinsewater at 5% of
bath strength.  The performance parameters listed for each membrane are
conductivity rejection, copper rejection, free cyanide rejection, and flux.
Rejections are given as a percentage of the feed concentration rejected,
and flux, for the most part, is given in liters per square meter of membrane
surface per hour (l/m2-hr).  For the hollow-fiber modules (NS-200 and B-9),
the productivity is reported in cc/min since: 1) the exact surface area is
difficult to determine, and  2) the productivity per unit membrane area
could not be usefully compared to the flux for flat-sheet membranes because
of the much higher packing density (m2/m3) possible with the hollow-fiber
configuration.                       ;

     The results in Table 7 indicate that all of the membranes tested
exhibited reasonably stable flux and rejection for the 500-hour life test at
5% of bath strength.  The apparent drop in conductivity rejection for the
NS-100, NS-200, SPPO, and B-9 membranes is believed to  have resulted
from the absorption of atmospheric "C02, which gradually changed the
pH of the test solution and shifted the ionic equilibria in the direction of
more poorly rejected species.  The copper and free cyanide rejections for
  Actual sampling times varied slightly from the 24, 250, and 500-hour
  times shown.

                                     17

-------
TABLE  7.  MEMBRANE PERFORMANCE
           RINSEWATER AT 5% OF
 DURING LIFE TEST WITH COPPER CYANIDE
BATH STRENGTH (pH=10-13)

Membrane
PA-300



PBIL



NS-100
(avg of 6)


NS-200
(tubular)


NS-200-1
(Hollow-
fiber)

NS-200-2
(Hollow-
fiber)

SPPO



B-9





Performance
parameter
Conductivity rejection., %
Copper rejection, %
Free cyanide rejection, %
Flux, l/m2-hr
Conductivity rejection, %
Copper rejection, %
Free cyanide rejection, %
Flux, l/m2-hr !
Conductivity rejection, %
Copper rejection, %
Free cyanide rejection, %
Flux, l/m2-hr
Conductivity rejectipn, %
Copper rejection, %
Free cyanide rejection, %
Flux, l/m2-hr
Conductivity rejection, %
Copper rejection, %
Free cyanide rejection, %
Flux, cc/min
Conductivity rejection, %
Copper rejection, %
Free cyanide rejectipn, %
Flux, cc/min
Conductivity rejection, %
Copper rejection, % i
Free cyanide rejection, %
Flux, l/m2-hr
Conductivity rejection, %
Copper rejection, %
Free cyanide rejectipn, %
Flux, cc/min j
i


Level at
24 hrs
97.5
99.1
98.2
25
85.4
99.3
97.2
22
91.1
96.7
91 .4
11
86.8
97.6
93.1
20
96.1
99.0
96.7
51
94.2
99.9
98.9
26
83.1
95.4
88.3
44
97.5
99.9
98.5
1.8


Level at
250 hrs
97.8
98.0
96.7
16
90.0
98.5
94.3
14
91.3
96.3
90.0
8.7
88.9
97.6
91.8
23
96.1
99.8
97.0
58
95.9
99.9
97.9
35
82.2
91.7
79.9
5.1
96.7
99.3
97.0
2.0


Level at
500 hrs
97.9
98.9
99.2
15
90.5
98.7
98.8
14
86.4
96.2
94.3
9.3
74.7
97.5
94.8
25
87.4
99.7
98.6
54
(epoxy
pot
failure)

68.2
94.9
92.8
7.5
90.5
99.4
98.8
1.7

                                18

-------
these same membranes showed no significant decline during the test.   In
subsequent tests, polyethylene spheres were added to the feed tank to cut
down the amount of C02 absorption, and the pH was more carefully controlled.

     In general, the PA-300, NS-200, and B-9 membranes gave the highest
rejections of conductivity, copper, and free cyanide.  Relative to these
membranes the PBIL membrane gave equivalent rejections of copper and free
cyanide but somewhat lower conductivity rejections.  The NS-100 and SPPO
membranes gave lower rejections, particularly for copper and free cyanide.

     The results for the 500-hour life test at 25% of bath strength are
given in Table 8.  At this concentration the PBIL, NS-200, SPPO, and B-9
membranes showed significant degradation in performance characteristics.
For the PBIL membrane the flux decreased to an extremely low level upon
exposure to the 25%-of-bath rinsewaters.  The rejections are also poor
(<90%), probably as the result of the very low flux.  Both NS-200 hollow-
fiber modules seemed to perform reasonably well  until after about 250 hours.
After this time one of the modules failed,resulting in gross leakage between
the feed and permeate sides, and the other module exhibited sharp declines
in conductivity, copper, and cyanide rejections.  The SPPO membrane exhibited
extremely low rejections of all species,and rejections decreased with time
indicating degradation of the membrane material.  For the B-9 membrane the
rejections of copper and cyanide declined at a moderate rate, but the flux
of the membrane declined rapidly.

     Only the PA-300 and NS-100 membranes showed no serious degradation in
performance during the tests with the 25%-of-bath rinsewaters.  Of these
two membranes the PA-300 is clearly superior.  The conductivity rejection was
quite good, the copper and free cyanide rejections were excellent, and the
flux was high.  Both flux and rejection were stable throughout the test.  On
the other hand,the NS-100 rejections were rather poor and the flux was only
moderate.  It is concluded that, for the treatment of copper cyanide
rinsewaters, PA-300 is the best of the membranes tested.

ZINC CYANIDE

     Following the tests with copper cyanide rinsewaters at 25% of bath
strength, the NS-200 hollow-fiber modules were replaced with two new
modules, and a new B-9 mini-permeator was installed.  The NS-100 and SPPO
membranes were not changed prior to the zinc cyanide tests.  The PA-300 and
PBIL membranes were not obtained in time for the zinc cyanide tests at 5%
of bath strength but were tested at 25% of bath strength.  However,  samples
of PA-300 and PBIL membrane were not obtained until after the test at 25%
of bath strength had been initiated, and so the total exposure time for
these membranes (391 hours for the PA-300 membrane and 315 hours for the PBIL
membrane) were somewhat lower than the usual 500 hours.  Use of NS-200
tubular modules was discontinued for these and subsequent tests because of
difficulties encountered in their fabrication.
                                     19

-------
TABLE 8. MEMBRANE PERFORMANCE DURING LIFE TEST WITH  COPPER
         CYANIDE RINSEWATER AT 25% OF BATH STRENGTH  (pH=11-13)

Membrane
PA-300



PBIL




NS-100
(avg of 6)


NS-200
(tubular)


NS-200-1
(Hollow- fiber)


NS-200-2
(Hollow-fiber)


sppo



B-9,





Performance
parameter
Conductivity rejection, %
Copper rejection, |%
Free cyanide rejection, %
Flux,. J/m2-hr
Conductivity rejection, %
Copper rejection, '%
Free cyanide rejection, %
Flux, l/m2-hr 1

Conductivity rejection, %
Copper rejection, •%
Free cyanide rejection, %
Flux, l/m2-hr
Conductivity rejection, %
Copper rejection, %
Free cyanide rejection, •%
Flux, l/m2-hr
Conductivity rejection, %
Copper rejection, %
Free cyanide rejection, %
Flux, cc/min
Conductivity rejection, %
Copper rejection, %
Free cyanide rejection, %
Flux, cc/min
Conductivity rejection, %
Copper rejection, %
Free cyanide rejection, %
Flux, l/m2-hr ;
Conductivity rejection, %
Copper rejection, %
Free cyanide rejection, %
Flux, cc/min


Level at
24 hrs
96.3
98.9
98.6
15
60.6
89.3
87.2
1.4

75.1
92.3
92.6
7.1
51.9
88.7
88.5
29
69.2
98.0
96.8
27.5
77.9
99.0
98.1
25
31.7
55.8
68.5
15
75.4
99.1
98.4
0.6


Level at
250 hrs
97.0
99.0
99.0
13
61.3
86.4
89.6
1.2

76.4
90.0
91.0
7.0
46.4
72.8
81.9
46
73.2
96.0
95.6
33
77.9
•-•-97.7
96.4
30
25.0
38.6
63.9
13
79.1
96.8
95.7
0.2


Level at
500 hrs
98.0
99.3
98.8
13
56.7
75.4
77.0
1.5
fc
78.5
86.7
90.2
6.8
42.2
54.5
68.8
49
16.7
0.0
2.6
164
55.6
66.1
55.2
32
24.1
30.4
39.1
6.8
79.6
94.2
92.4
0.1

                         20

-------
     Table 9 gives the results for the test with the 5%-of-bath rinsewater.
All of the membranes tested appeared to be reasonably stable at this rinse-
water concentration, and the commercially available B-9 membrane appeared
to have the highest overall rejections.  The low rejections for the SPPO
membrane were probably the result of membrane deterioration during testing
with 25%-of-bath copper cyanide rinsewater.

     Results for the life-test with 25%-of-bath zinc cyanide rinsewater are
given in Table 10.  Again, all of the membranes tested exhibited reasonably
stable performance.  However, except for the PA-300 membrane the flux and/or
rejections of the membranes were too low for cost-effective recovery of zinc
cyanide rinsewaters at this concentration.  The low conductivity rejections
(generally <50% except for the PA-300 membrane) could be the result of the
high concentration of hydroxide ion (which is difficult to reject) in the
zinc cyanide rinsewaters.  The PA-300 membrane, by contrast, gave excellent
zinc and free cyanide rejections and a conductivity rejection much higher
than any of the other membranes.  In addition, the flux for PA-300
was quite high and appeared to be leveling off at a stable value of about
20-22 l/m^-hr. On the basis of these data,it is concluded that,for the treat-
ment of zinc cyanide rinsewaters,PA-300 is the best of the membranes tested.

ACID COPPER

     Following the tests with the zinc cyanide rinsewater at 25% of bath
strength, new PA-300, PBIL , and NS-200 membranes  were installed in the
system; however, the NS-100 membranes were not changed since new samples of
these membranes were not available.  The SPPO membrane was replaced prior
to the test at 25% of bath strength, but during initial characterization
tests with a sodium chloride solution, it was discovered that the new SPPO
membrane was giving very poor rejections (<60%).  This membrane was there-
fore eliminated from the test program.  The B-9 membrane, which served as
a reference membrane for alkaline solutions, was replaced by a CA reference
membrane for tests with acid copper and chromic acid solutions.  However, the
CA membrane was not installed in the test system until after the test with
5%-of-bath acid copper rinsewater.

     Results are shown in Table 11 for the life test with acid copper rinse-
water at 5%-of-bath strength.  The PBIL membrane exhibited exceptionally
high rejections for all species,including conductivity (rejection >99%), and
the rejections appeared to be stable.  Although the flux (~ 7 l/m2-hr) was
rather low, it is believed that membranes with a higher flux could be pre-
pared by varying the casting procedure.  (This membrane was still in the
process of being optimized when the test sample of membrane was obtained.)
The NS-200 membrane also exhibited quite good performance characteristics
during this test.  Both the flux and rejection for this membrane appear
adequate for successful application to copper sulfate rinsewaters.  The
PA-300 membrane gave a lower level of performance, and the NS-100 performed
poorly in this test.  It is possible that the copper ions in the rinsewater
complexed with amine groups on the NS-100 membrane surface (and to a lesser
extent on the PA-300 surface),resulting in poor rejection performances.
                                     21

-------
TABLE 9.  MEMBRANE PERFORMANCE DURING LIFE TEST WITH ZINC
Membrane
NS-100
(avg of 6)
Performance
parameter
Level at
24 hrs
Conductivity rejection, % 72.8
Zinc rejection, %
—
Free cyanide rejection, % 88.4
Flux, l/m2-hr [ 11
NS-200
(avg of 2)
Conductivity rejection1, % 66.4
Zinc rejection, % \
Free cyanide rejection, % 96.8


sppo

Flux, cc/min

100

Conductivity rejection, % 25.0
Zinc rejection, %
--
Free cyanide rejection,, % . 50.0
Flux, l/m2-hr ' 12
. i
B-9

Conductivity rejection, % 74.4
Zinc rejection, %
-_
Free cyanide rejection1, % 97.3

Flux, cc/min
1.1
Level at
250 hrs
75.2
97.6
92.7
11
57.1
99.7
95.4
116

28.8
73.2
63.1
8.8
81.3
99.95
98.5
1.0
Level at
500 hrs
81.0
96.8
91.1
9.5
67.0
99.2
90.4
96

41.0
75.0
53.2
8.5
83.0
99.8
97.7
0.76
                            22

-------
TABLE 10.  MEMBRANE PERFORMANCE DURING LIFE TEST WITH ZINC CYANIDE
           RINSEWATER AT 25% OF BATH STRENGTH (pH>13)

Membrane
PA- 300



PBIL



NS-100
(avg of 6)


NS-200
(avg of 2)


SPPO



B-9



Performance
parameter
Conductivity rejection, %
Zinc rejection, %
Free cyanide rejection, %
Flux, l/m2-hr
Conductivity rejection, %
Zinc rejection, %
Free cyanide rejection, %
Flux, l/m2-hr
Conductivity rejection, %
Zinc rejection, %
Free cyanide rejection, %
Flux,l/m2-hr
Conductivity rejection, %
Zinc rejection, %
Free cyanide rejection, %
Flux, cc/min
Conductivity rejection, %
Zinc rejection, %
Free cyanide rejection, %
Flux, l/m2-hr
Conductivity rejection, %
Zinc rejection, %
Free cyanide rejection, %
Flux, cc/min
Level at
24 hrs
86.9
99.1
97.4
31
35.8
—
—
1.9
42.3
87.9
77.5
5.9
35-0
93.2
80.8
76
33.0
40.0
46.0
9.3
29.0
98.1
89.2
0.13
Level at
250 hrs
86.2
—
—
25
42.9
—
—
1.9
33 3
76.1
83.2
36
8.8
95.0
88.7
82
0.0
43.8
42.9
14
41.2
98.0
94.9
0.19
Level at
500 hrs
86.5
99.3
96.7
22
52.4
95.9
90.9
* 1.5
41.6
72,1
63.1
29
31.4
93.6
82.6
76
33.9
53.9
27.2
3.6
53.2
95.2
90.6
0.10
                                23

-------
TABLE 11.  MEMBRANE PERFORMANCE DURING LIFE TEST WITH ACID COPPER
           RINSEWATER AT 5%jOF BATH STRENGTH (pH=1.2)

Membrane
PA-300



PBIL



NS-100
(avg of 6)


NS-200
(avg of 2)


Performance
parameter
Conductivity rejection, %
Copper rejection, %
Sulfate rejection, %
Flux, l/m2-hr
Conductivity rejection, %
Copper rejection, %
Sulfate rejection, %
Flux, l/m2-hr
Conductivity rejection, %
Copper rejection, %
Sulfate rejection, %
Flux, l/m2-hr
Conductivity rejection, %
Copper rejection, %
Sulfate rejection, %
Flux, cc/min
Level at
24 hrs
79.7
99.7
92.9
54
99.4
>99.9
99.9
6.1
20.0
94.7
49.8
19
97.3
99.9
98.7
43
Level at
250 hrs
89.2
—
—
39
99.1
—
—
12
49.6
—
—
27
97.3
--
—
38
Level at
500 hrs
82.6
—
94.8
24
99.5
__
98.0
6.8
24.2
--
57.1
32
96 ..1
—
98.1
31

                             24

-------
     For all membranes the rejections remained reasonably stable with
operating time, but significant declines in flux were observed for the
PA-300 and NS-200 membranes.  Results for copper rejection are incomplete
because of immersion deposition of copper on various stainless steel compon-
ents within the test system.  Copper concentrations in the feed solution
decreased to very low levels following the first analysis at 24 hours.

     Results are shown in Table 12 for the life  test with acid copper  rinse-
water at 25% of bath strength.  Immersion deposition was not a problem
during this test since significant deposition had already occurred in  the
previous test, and copper concentrations in the feed were much higher.
Again the PBIL membrane exhibited extremely high rejection of all  species,.
but the flux was low.  The flux and rejections were reasonably stable  for  the
duration of the test,with the exception of sulfate rejection.  The performance
of the NS-200 membrane declined relative to that shown during the test at  5%
of bath strength, but is still considered adequate for successful  application
of this membrane.  The rejection of conductivity, copper, and sulfate  in-
creased during the test, and the flux appeared to stabilize after an initial
decline.  One of the two NS-200 modules had to be removed from the test
system after 494 hours of operation due to weld failures in its stainless
steel housing; therefore,data after this point could not be obtained.   The
PA-300 membrane exhibited excellent copper rejections, but the sulfate  and
conductivity rejections were low.  The PA-300 rejections generally increased
with operating time, but the flux decreased substantially during the life
test to only one-third of its initial value.  The NS-100 membranes exhibited
very poor but stable rejections and a substantial decrease in flux over the
duration of the test.  The CA membrane was degraded by acid hydrolysis  at  the
low pH of the rinsewater.  This deterioration was evidenced by a substantial
loss in rejection with a simultaneous increase in flux.

     On the basis of these life tests, it is concluded that the NS-200  and
PBIL membranes exhibit the best performance characteristics for treatment  of
acid copper rinsewaters.

CHROMIC ACID

     Following the tests with acid copper, new.PA-300 and PBIL membranes were
installed in the test system, while one each of the same NS-100 and NS-200
membranes were retained.  For the test at 25% of bath strength, use of the
NS-200 was discontinued because of severe membrane degradation.

     Results of the life test at 5% of bath strength are shown in Table 13.
Of the membranes tested,only the PA-300 and PBIL gave stable performance.
For the NS-100, NS-200, and CA membranes, the rejections decreased and the
flux levels increased with operating time.  This behavior is indicative of
chemical degradation of the membrane surfaces.

     Both the PA-300 and the PBIL membr.anes gave exceptionally stable  flux
and rejection performances throughout the life test.  Of these two membranes,
PA-300 performed better in both flux and rejection.
                                     25

-------
TABLE 12.  MEMBRANE PERFORMANCE DURING LIFE TEST WITH ACID COPPER
           RINSEWATER AT 25% OF BATH STRENGTH (pH=0.6-0.9)
Membrane
PA-300



PBIL



NS-100
(avg of 5)


NS-200-1



NS-200-2



CA



Performance
parameter
Conductivity rejecti
Copper rejection, %
Sulfate rejection, %
Flux, l/m2-hr
Conductivity rejecti
Copper rejection, %
Sulfate rejection, %
Flux, l/m2-hr
Conductivity rejecti
Copper rejection, %
Sulfate rejection, %
Flux, l/m^-hr
Conductivity rejecti
Copper rejection, %
Level at
24 hrs
an, % 78.1
99.9
76.5
22
on, % 99.2
>99.9
99.3
6.6
an, % 26.7
98.2
1.8
24
jn, % 86.5
97.8
Sulfate rejection, % 86.1
Flux, cc/min 25
Conductivity rejecti
>n, % 92.1
Copper rejection, % 99.58
Sulfate rejection, %
92.8
Flux, cc/min 29.5
Conductivity rejection, % 92.3
Copper rejection, % | 99.9
Sulfate rejection, %\ 92.0
Flux, l/m2-hr 8.0
Level at
250 hrs
82.6
>99.9
92'. 2
10
98.3
>99.9
98.1
4.2
31.5
98.3
60.4
14
84.8
98.5
91.2
17
92.2
99.74
97.2
22
57.8
97.2
74.9
15
Level at
500 hrs
90.0
>99.9
83.0
6.1
99.1
>99.9
94.4
4.8
47.2
96.0
60.9
8.0
91.3
99.0
94.9
18.5
(weld
failure
in
housing)
39.1
83.3
49.2
17
                              26

-------
TABLE 13.  MEMBRANE PERFORMANCE DURING LIFE TEST WITH CHROMIC ACID
           RINSEWATER AT 5% OF BATH STRENGTH (pH=1.3-1.7)
Membrane
PA- 300


PBIL


NS-tOO


NS-200


CA


Performance
parameter
Conductivity rejection, %
Chromium (VI) rejection, %
Flux, l/m2-hr
Conductivity rejection, %
Chromium (VI) rejection, %
Flux, l/m2-hr
Conductivity rejection, %
Chromium (VI) rejection, %
Flux, l/m2-hr
Conductivity rejection, %
Chromium (VI) rejection, %
Flux, cc/min
Conductivity rejection, %
Chromium (VI) rejection, %
Flux, l/m2-hr
Level at
24 hrs
97.9
98.8
13
95.0
96.8
6.5
43.3
51.0
17
28.3
25.8
17
96.2
97.3
19
Level at
250 hrs
97.8
98.9
17
95.0
96.6
12
23.1
42.9
61
0.0
11.4
140
88.5
91.4
46
Level at
500 hrs
97.5
98.6
15
94.1
96.3
15
22.7
67.4
75
0.0
18.0
150
31.8
42.0
102
                                27,

-------
     Results for the life test with chromic acid at 25% of bath strength
are shown in Table 14.  The NS-loq and CA membranes degraded quite rapidly,
and the evaluation of these membranes had to be discontinued shortly after
the life test was initiated.  The PBIL membrane was operated for the entire
500-hour test, but the rejections jof both conductivity and hexavalent
chrome declined substantially.  On the other hand, the PA-300 membrane
exhibited very good conductivity Rejection and excellent chromium rejection
during the entire life test.  Although the flux was low, it appeared to be
reasonably stable.  It is believed that, despite the low flux, PA-300 could
be used economically to recover chromic acid rinsewater because of the rela-
tively high value of the recovered chemicals.
                                  i
     It is concluded that, of the membranes tested, PA-300 is the only one
suitable for the treatment of chromic acid rinsewater.
                                     28

-------
TABLE 14.  MEMBRANE PERFORMANCE DURING LIFE TEST WITH CHROMIC ACID
           RINSEWATER AT 25% OF &ATH STRENGTH (pH=l.1-1.2)

Membrane
PA-300
PBIL
NS-100
CA
Performance
parameter
Conductivity rejection, %
Chromium (VI) rejection, %
Flux, l/m2-hr
Conductivity rejection, %
Chromium |VI) rejection, %
Flux, l/m2-hr
Conductivity rejection, %
Chromium (VI) rejection, %
Flux, l/m2-hr
Conductivity rejection, %
Chromium (VI) rejection, %
Flux, l/m2-hr
Level at
24 hrs
95.9
97.9
9.2
92.2
96.1
6.8
15.7
33.2
7.2
75.3
85.7
37
Level at Level at
250 hrs 500 hrs
97.3 97.5
99.1 98.8
4:2 5.3
77.7 73.3
90.8 83.4
4.8 8.7
(test discontinued)
(test discontinued)
                                 29

-------
                                  REFERENCES
1.   Skovronek, H.S., and M.K. Stinson,  Advanced Treatment Approaches  for
     Metal Finishing Wastewaters (Part II).   Plating and  Surface  Finishing,
     64(11): 24-31, 1977.         !

2.   Donnelly, R.6., R.L. Goldsmith, K.J.  McNulty,  and  M.  Tan.  Reverse
     Osmosis Treatment of Electroplating Wastes.  Plating,   61(5):  432-442,
     1974.

3.   Donnelly, R.6., R.L. Goldsmith, K.J.  McNulty,  D.C. Grant,  and
     M. Tan, Treatment of Electroplating Wastes  by  Reverse Osmosis,
     EPA-600/2-76-261, U.S. Environmental  Protection Agency,  Cincinnati,
     Ohio, 1976.  96 pp.          I

4.   McNulty, K.J., R.L. Goldsmith, and  A.Z.  Gollan, Reverse  Osmosis Field
     Test:  Treatment of Watts Nickel  Rinse Waters.  EPA-600/2-77-039,
     U.S. Environmental Protection Agency, Cincinnati,  Ohio,  1977. 29  pp.
                                  i
5.   Golomb, A., Application of Reverse  Osmosis  to  Electroplating  Waste
     Treatment (Part III.  Pilot Plant Study  and Economic Evaluation of
     Nickel Recovery).  Plating, 60(5):   482-486, 1973.

6.   McNulty, K.J., R.L. Goldsmith, A. Gollan, S. Hossain, and  D.  Grant,
     Reverse Osmosis Field Test:  [Treatment of Copper Cyanide Rinse
     Waters.  EPA-600/2-77-170, U.;S. Environmental  Protection Agency,
     Cincinnati, Ohio, 1977.  89 p|p.
                                     30

-------















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                                    TECHNICAL. REPORT DATA
                             (Please read Instructions on the reverse before completing)
1. REPORT NO.
  EPA-600/2-80-084
                              2.
                                                             3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
  EVALUATION  OF  REVERSE OSMOSIS MEMBRANES FOR TREATMENT
  OF ELECTROPLATING RINSEWATER
              5. REPORT DATE
               May  1980 issuing date
              6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
  Kenneth'J. McNulty and Peter R. Hoover
  Walden  Division of Abcor, Inc., Wilmington, MA 01887
                                                             8. PERFORMING ORGANIZATION REPORT NO
9. PERFORMING ORGANIZATION NAME AND ADDRESS

  The American  Electroplaters1 Society
  1201 Louisiana  Avenue
  Winter Park,  Florida 32789
              10. PROGRAM ELEMENT NO.

                1BB610
              11. CONTRACT/GRANT NO.

                R804311
12. SPONSORING AGENCY NAME AND ADDRESS
  Industrial  Environmental Research  Laboratory - Cinn, OH
  Office of  Research and Development
  U.S. Environmental Protection Agency
  Cincinnati,  OH  45268	
              13. TYPE OF REPORT AND PERIOD COVERED
              Final 3/1/76 -  10/19/77	
              14. SPONSORING AGENCY CODE

                EPA/600/12
15. SUPPLEMENTARY NOTES
  Project Officer:  Mary Stinson (201) 321-6683
16. ABSTRACT
      Because of the limited pH range over which  current commercially available reverse
   osmosis membranes can  be  applied, a test program was initiated to define  the
   applicability of new membrane materials to the  treatment of rinsewaters with extreme
   pH  levels and high oxidant levels (chromic acid).   Life tests were conducted with the
   PA-300, PBIL, NS-100,  NS-200, SPPO, B-9, and CA membranes on rinsewaters  from copper
   cyanide, zinc cyanide,  acid copper, and chromic acid plating baths.  The  PA-300
   membrane exhibited suprior performance for the  treatment of copper cyanide,  zinc
   cyanide, and chromic acid rinsewaters, and further development and demonstration of
   this  membrane is recommended.  The NS-200 and PBIL membranes exhibited the best per-
   formance for treatment  of acid copper rinsewaters.  Efforts are underway  to
   commercialize all three of the selected membranes  (PA-300, NS-200, and PBIL).
17.
                                KEY WORDS AND DOCUMENT ANALYSIS
                  DESCRIPTORS
                                               b.lDENTIFIERS/OPEN ENDED TERMS  C. COSATI Field/Group
  Electroplating
  Waste Treatment
  Reverse Osmosis
 Reverse  Osmosis
 Membranes:
 PA-300
 PBIL
 NS-100
 NS-200
 SPPO
    13B
18. DISTRIBUTION STATEMENT

  RELEASE. TO PUBLIC
19. SECURITY CLASS (ThisReport)
 UNCLASSIFIED
21. NO. OF PAGES

      51
                                               20. SECURITY CLASS (Thispage)
                                                 UNCLASSIFIED
                                                                           22. PRICE
EPA Form 2220-1 (Rev. 4-77)   PREVIOUS EDITION is OBSOLETE, o
                                                                  * U.S. GOVERNMENT PRINTING OFFICE: 1980-657-146/5676

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