EPA-440/1-75/040
  GROUP I, PHASE II
    Development Document for Interim
   Final Effluent Limitations Guidelines
        and Proposed Nkw Source
         Performance Standards
                 for the

   COMMON  AND  PRECIOUS METALS
             Segment of the

           ELECTROPLATING
         Point Source Category

UNITED STATES ENVIRONMENTAL PROTECTION AGENC

                April 1975

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               DEVELOPMENT DOCUMENT

                       for

        INTERIM FINAL EFFLUENT LIMITATIONS

                       and

         NEW SOURCE PERFORMANCE STANDARDS

                     for the

   COMMON AN^ PRECIOUS  METALS SEGMENT OF THE
ELECTROPLATING MANUFACTURING POINT SOURCE CATEGORY
                                                          V

                  Russell Train
                  Administrator
                  James L. Agee
        Assistant Administrator for Water
             and Hazardous Materials
                   Allen Cywin
      Director, Effluent Guidelines Division
               Kit R. Krickenberger
                 Project Officer
                   April, 1975
           Effluent Guidelines Division
     Office of Water and Hazardous Materials
      U. S. Environmental Protection Agency
             Washington, D.C.   20460

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                          ABSTRACT
This document presents the findings of an extensive study of
the electroplating industry by the Environmental  Protection
Agency  for  the  purpose of developing effluent limitations
guidelines.   Federal   standards   of   performance,    and
pretreatment   standards  for  the  industry,  to  implement
Sections 304, 306, and 307 of the  Federal  Water  Pollution
Control  Act,  as  amended  (33 USC 1251, 1314, and 1316; 86
Stat 816) .

Effluent limitations guidelines contained herein  set  forth
the  degree  of  effluent  reduction  attainable through the
application  of  the  best  practicable  control  technology
currently  available  and  the  degree of effluent reduction
attainable through the application  of  the  best  available
technology economically achievable which must be achieved by
existing  point  sources  by  July  1, 1977 and July 1, 1983
respectively.  The standards of performance for new  sources
contained  herein set forth the degree of effluent reduction
which is achievable through  the  application  of  the  best
available   demonstrated   control   technology,  processes,
operating methods, or other alternatives.

In developing the data and recommendations in this  document
the  electroplating  processes  have  been considered as one
subcategory.  Reasons for this  decision  may  be  found  in
section  IV  of this document.  This subcategory consists of
processes for electroplating of  copper,  nickel,  chromium,
zinc,  tin,  lead,  cadmium,  cobalt,  iron,  silver,  gold,
platinum, palladium,  indium,  antimony,  rhodium,  iridium,
ruthenium,   titanium,   or   combination  thereof  and  the
salvaging  process  of  stripping.   The  electroplating  of
copper,  nickel,  chromium and zinc was covered in the first
development document.  The remainder  are  covered  in  this
document.

Chemical  treatment  of  waste  waters to destroy oxidizable
cyanide, reduce hexavalent  chromium,  and  remove  all  but
small  amounts of the metals represents the best practicable
control technology currently available  for  existing  point
sources in this subcategory.

Chemical  treatment  of  waste  waters to destroy oxidizable
cyanide, reduce hexavalent  chromium,  and  remove  all  but
small  amounts of metals, augmented by in-process procedures
to further reduce the amount of waste water  and  the  total
pollutional  load is the new source performance standard for
point sources in this subcategory.

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The best available technology economically achievable to  be
achieved  by  1983  is  no  discharge of process waste water
pollutants to navigable waters.

Supportive  data  and  rationale  for  development  of   the
proposed  effluent  limitations  guidelines and standards of
performance are contained in this report.
                               11

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                        CONTENTS
II
 III
  IV
   V
    VI
CONCLUSIONS

RECOMMENDATION*
                                   Tecnnology
             Achievable         e standards
           New Source Pen
Page_

  1

   3

   3

   3
   6
          INTRODUCTION
               Authority       Development
                       st^11""
     introduction       orization
     Objectives  £ C»ctlon —

     factor** Considered in


      introduction       Waste

      —.t^f wfte? Uses
                WaSt£epoflutional Significance
                       n            o£ Efu
                  Chemical Treatmen^ Qpera

                  Wafefconservation Through Cont

                    Technology
                                              11
                                              11
    12

     13

     17
     17
     17
     17
     27

      37
      37
      37
      37
      44

       81
       81

       81

       82

        95
        95
        98
                                                   111

                                                   114

                                                    121
                                 iii

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            Methods of Achieving No Discharge
              of Pollutants                             149

VIII      COSTS, ENERGY, AND NONWATER QUALITY ASPECTS   153
            Introduction                                153
            Treatment and Control Costs                 153
            Nonwater Quality Aspects                    175

IX        BEST PRACTICABLE CONTROL TECHNOLOGY
            CURRENTLY AVAILABLE, GUIDELINES,            181
            AND LIMITATIONS                             " ~>1
            Introduction                                181
            Identification of Best Practicable
              Control Technology Currently
              Available                                 182
            Rationale for Selecting the Best
              Practicable Control Technology
              Currently Available                       184

X         BEST AVAILABLE TECHNOLOGY ECONOMICALLY
            ACHIEVABLE, GUIDELINES AND LIMITATIONS      273
            Introduction                                273
            Industry Category and Subcategory
              Covered                                   274
            Identification of Best Available
              Technology Economically Achievable        274
            Rationale for Selection of Best
              Available Technology Economically
              Achievable                                275
            Effluent Limitations Based on the
              Application of Best Available
              Technology Economically Achievable        277
            Guidelines for the Application of
              Effluent Limitations                      277

XI        NEW SOURCE PERFORMANCE STANDARDS              279
            Introduction                                279
            Industry Category and Subcategory
              Covered                                   280
            Identification of Control and Treatment
              Technology Applicable to Performance
              Standards and Pretreatment Standards
              of New Sources                            281
            Rationale for Selection of Control and
              Treatment Technology Applicable to
              New Source Performance Standards          282
            Standards of Performance Applicable
              to New Sources                            283
            Guidelines for the Application of
              New Source Performance Standards          283
                           IV

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XII       ACKNOWLEDGEMENTS                             285




XIII      REFERENCES                                   287




XIV       GLOSSARY                                     293
                              v

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                           TABLES
Number

   1     BPCTCA Limitations for Electroplating
           of Common Metals and Precious Metals
           Subcategories                              4 5

   2     NSPS Limitations for Electroplating of
           Common and Precious Metals Subcategories    7,8

   3     Processes for Plating on  Plastics             22

   U     Processes for Plating on  Steel                23

   5     Processes for Plating on  Substrate  Materials
           Other Than Steel                           24

   6     Processes for Chemical Conversion Coatings    28

   7     Processes for Metal Coloring                 29

   8     Estimated Daily Raw Waste Load  of Principal
           Salts Used In Cu,  Ni, Cr,  Zn  Plating and
           Related Processes                           41

   9     Wastewater Constituents from Treatment
           Before Plating                             42

 10     Principal  Wastewater Constituents in
           Wastes Generated  During Pretreatment for
           Electroless  Plating  on Metals and Plastics  43

 11     Alkaline Cleaners for Aluminum                45

 12     Representative  Deoxidizing and Desmutting
           Treatments for Aluminum                     47

 13      Representative Alkaline Cleaners for
           Magnesium                                   4g

 1U      Representative Constituents  from Plating
           Operations                                  5Q

 15     Chromate Coating of Magnesium By The
          Chrome Pickle Process                       63

 16     Dichromate Process Cycle for Magnesium Alloys  65
                             VI

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17     Principal Wastewater Constituents in Wastes
         Generated During Phosphating Operations
         on Various Metals and Alloys                68

18     Principal Wastewater Constituents in Wastes
         Generated During Immersion Plating of Tin,
         Copper, Gold and Nickel                     70

19     Principal Wastewater Constituents in Wastes Generated
         During Preparation for Immersion Plating on
         Various Basis Metals                        71

20     Principal Wastewater Constituents in Wastes
         Generated During Pretreatment for Metal
         Coloring                                    73

21     Principal wasatewater Constituents in Wastes
         Generated During Coloring of Copper
         and Brass                                   74

22     Principal Wastewater Constituents in Wastes
         Generated During Coloring of Iron and  Steel 75

23     Principal Wastewater Constituents in Wastes
         Generated During Coloring of Zinc           76

24     Principal Wastewater Constituents in Wastes
         Generated During Coloring of Cadmium        77

25     Principal Wastewater Constituents in wastes
         Generated During Coloring of Silver, Tin
         and Aluminum                               78

26     Comparison  of Soluble  Pollutant  Parameters
         After Precipitation  by Iron Sulfide or by
         Hydroxide                                   107

 27     Decomposition Products of Cyanide             us

 28     Costs  for Waste Treatment Facilities          154

 29     Treatment Equipment Costs                    157

 30     Annual Operating Costs                       158

 31      Investment and Annual  Operating Costs  for
          Average Plant                              161

 32      Cost Effectivenss of control  Alternatives    176
                             Vll

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 33     Cost of Power Relative to Total Operating
          Costs for Chemical Treatment               177

 3>\     Effluent Discharges - Plant 11-8             i87

 35     Cyanide Treatment Results - Plant 11-8        188

 36     Chromium Reduction Results - Plant 11-8       191

 37     Effectiveness of Clarifier - Plant 11-8       192

 38     Summarized  Effluent Flow  - Plant 11-8         194

 39     Summarized  Data  on Areas  Plated -
          Plant 11-8                                  196

 40     Water Use Factors - Plant 11-8                197

 41     Cyanide Treatment Results - Plant  33-20       200

 42     Chromium Reduction Results -  Plant 33-20      202

 43     Effectiveness  of  Clarifier -  Plant 33-20      204

 44     Effluent Flow  Data - August 20,  197U -
          Plant 33-20                                 206

 45     Effluent Flow  Data « August 21,  1974 -
          Plant 33-20                                 207

 46      Effluent Flow  Data - August 22,  1974 -
          Plant 33-20                                 208

 47      Flow Leaving Cyclator - Plant 33-20           209

 48      Holding  Tank Levels - Plant 33-20             2ll

 49      Areas Plated - August 20,   1974 -
         Plant  33-20                                 214

 50     Areas Plated - Tin Lines - August 20, 1974 -
         Plant  33-20                                 215

51     Collection Rates and Volumes of Sampling -
         Plant  36-1                                  218

52     Volume Discharged - Plant  36-1                219

53     Effluent Discharged - Plant 36-1              220
                              viii

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54     Area Plated - Plant 36-1                      222

55     Analysis of Raw and Treated wastes -          236

56     Effluent Quality and Standards -
         Plant 33-5                                  237

57     Plant Parameters - Plant 33-5                 238

58     Summary of Plant Data                         248

59     concentration Factors of Limitations          250

60     Monthly Data - Plant 15-1                     252,253

61     Monthly Data - Plant 12-6                     254

62     Monthly Data - Plant 33-15                    255

63     Electrochemical Equivalents                   260
                               IX

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                          FIGURES

Number                                                 „
	                                                 Page

   1     Water Uses for Common and Precious
           Metals Subcategories                          34

   2     Typical Flow of Water Through A
           Plating Line                                  3

   3     Typical Continuous Treatment Plant              97

   4     Typical Integrated Treatment System             99

   5     Batch Treatment of Cyanide                      100

   6     Sulfide Precipitation of Cadmium                117

   7     Treatment of Cadmium                            119

   8     Ion Exchange System                             129

   9     Evaporation  System                              135

  10     Reverse Osmosis System                          140

  11     Freezing System                                142

  12     Ion Flotation  System                           14g

  13     Investment Costs
                                                        166
  It     Operating  Costs

  15     Chemical Treatment-Coprecipitation Only         162

  16     Chemical Treatment-Cyanide Destruction
          and coprecipitation                           ,,_
                                                        J-b J

  17      Chemical Treatment-Chromium Reduction and
          Coprecipitation                               ,, .
                                                        Xb4

  18      Chemical Treatment-Cyanide Oxidation, Chromium
          Reduction, Coprecipitation                    165

  19      Master Flow Pattern                             ,c-
                                                        ID /

  20      Combined Treatment                              168

  21     Combined Treatment ]?ollowed By Reverse
         Osmosis

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22     Batch Treatment                                 170

23     Combination Batch and Continuous Treatment      189

21     Continuous Treatment                            198

25     Cyanide and Acid Wastes Treatment               217

26     waste Treatment - Plant 36-12                   226

27     Tin Plating Line - Plant 36-12                  227

28     Cu and Sn Plating Lines - Plant 36-12           228

29     Cu and Ag or Cu and Ni Plating Line -
         Plant 36-12                                   229

30     Effect Bright Dipping on Cu and Zn
         Concentrations                                231

31     Change in Average Effluent Concentrations
         and pH - Plant 36-12                          232

32     Process Diagram                                 235

33     Example 1                                       266

34     Example 2                                       269

35     Example 3                                       271

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                         SECTION I

                        CONCLUSIONS


For  the  purposes  of  establishing  effluent   limitations
guidelines    and   standards   of   performance   for   the
electroplating industry,  the  electroplating  point  source
category  has  been considered as three subcategories.  They
are the electroplating of common metals,  electroplating  of
precious   metals,  and  the  electroplating  of  speciality
metals.   The  industry  was  separated  into  these   three
categories on the basis of volume of metal plated, economics
of  plating  and differences of treatment technologies.  The
consideration of the age of the plant,  processes  employed,
geographical  location,  and  wastes  generated support this
conclusion.  Guidelines for the application of the  effluent
limitations  and  standards of performance take into account
the plant size in that the  allowable  amount  of  pollutant
that  can  be  discharged is proportic al to the size of the
plant.

Phase I of the study  covered  only  the  electrop. \ting  of
copper,  nickel,  chromium  and  zinc.   The results of this
study may be found in the "Development Document for Effluent
Limitations Guidelines and New Source Performance  Standards
for  the  Copper,  Nickel,  Chromium and Zinc Segment of the
Electroplating Point Source Category" March, 1974.  Phase II
- common metals subcategory applies to the electroplating of
tin,  lead,  aluminium,  cadmium,  and  iron.   Phase  II
precious metals subcategory applies to the electroplating of
silver,  gold,  platinum,  rhodium,  iridium, and ruthenium.
Phase II - speciality  metals  subcategory  applies  to  the
electroplating  of beryllium, magnesium, calcium, tellurium,
rhenium, cobalt and mercury.   At  publication,  limitations
will  be  recommended  only for electroplating of common and
precious metals.

The average cost for waste treatment reported by  30  plants
was  $1.06/1000  liters  of waste water treated.  Investment
costs ranged from $1.15 to $43.39/l/hr.  Estimates made from
two modeled waste  treatment  plants  carrying  out  cyanide
destruction,      chromate     reduction,     precipitation,
clarification and filtering were $1.09 and $1.41/1000 liters
of  waste  water  treated.   Investment  costs  ranged  from
$22,980  for  a  5-man plant plating 75 sq m/hr and treating
wastes only by neutralizing it  to  $378,U55  for  a  47-man
plant   plating  815  sq  m/hr  and  treating  for  cyanide,
chromate, and metals including clarification and  filtering.
A minimum cost batch waste treatment system was designed for

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$17,700.   This  system treats cyanide, chromate, and metals
but relies heavily on an operator for proper functioning and
many manual operations.  Operating costs were  estimated  to
be $10,186/yr exclusive of analytical costs.

The   best   practicable   control   technology   for   this
subcategory, is chemical treatment.  It is estimated that  a
water  use  of  160  1/sq  m/operation  can  be  achieved in
existing sources for the processes in this subcategory.

The best available  technology  economically  achievable  by
1983  is  no  discharge of process waste water pollutants to
surface waters.  The technology involved  consists  of  both
in-process  and  end-of-process  methods  of  minimizing and
eliminating water use and eliminating effluent.

The new source performance standards are based upon chemical
treatment  and  a  water  use  estimated  to  be   80   1/sq
m/operation.

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                         SECTION II

                      RECOMMENDATIONS


Best_Practicable control Technology Currently Available

Recommended  effluent  limitations  for  the  electroplating
industry  applicable  to  existing  sources  discharging  to
navigable  waters are summarized in Table 1 and the specific
effluent limitation guidelines and rationale  are  discussed
in  greater  detail  in  Section  IX  of  this report.   The
guidelines to be achieved by July 1, 1977 have been  derived
from the product of concentrations and water uses considered
achievable.   Chemical  treatment of waste waters to destroy
oxidizable cyanide, reduce hexavalent chromium,  and  remove
all  but  small  amounts of the metal pollutants by chemical
coprecipitation  represents  the  best  practicable  control
technology  currently  available (BPCTCAJ for existing point
sources.  A water use of 160 1/sq m per operation  has  been
found to be achievable by the industry.

Additional currently available in-process control technology
designed  to  recover  and reuse process chemicals and water
and reduce water consumption may be  required  to  meet  the
effluent  limitations depending upon the kind of parts being
finished or the nature of available process facilities.

Best_Ayailable Technology EconomicallyAchievable

The effluent limitations attainable through the  application
of  the best available technology economically achievable by
existing  point  sources  in  the  subcategories  listed  in
Section  I is no discharge of process waste water pollutants
to navigable waters by July lr 1983.  The achievement of  no
aqueous  discharge  of  process  waste  water  pollutants to
navigable waters  is  believed  to  be  possible  through  a
combination   of   technologies   that  are  being  employed
throughout the industry and are  in  the  process  of  being
developed   and   demonstrated.    There   is   considerable
information available on how to  reduce  water  use  in  the
plant  through proper design of processing lines and correct
operating procedures.  Minimizing this water  use  minimizes
the  problem  of  treating the waste water that is produced.
Reverse osmosis, electrodialysis, and  special  ion-exchange
systems  are  under  development to recycle water in process
loops and thereby reduce water to be treated  and  are  also
being  tested  for  recovery  of  process  water  from waste
effluent.   Already some electroplaters  have  been  able  to
eliminate  discharges  from  one  or  more  lines  within  a

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            Table 1 - BPCTCA Limitations
        for Electroplating of Common  Metals
                    Subcategory
Effluent                     Effluent
Characteristic               Limitations

                  Maximum for      Average of daily
                  any one day      values for thirty
                                   consecutive days
                                   shall not exceed

         (Metric units)    milligrams per sq m
                              per operation

Copper               160                  80
Nickel               160                  80
Cr,Total             160                  80
CrVI                   16                   8
Zinc                 160                  80
CN,Total             160                  80
CN,A                   16                   8
Fluoride            6400                3200
Cadmium               96                  18
Lead                 160                  80
Iron                 320                  160
Tin                  320                  160
Phosphate            320                  160
TSS                 6400                3200
pH                  Within the range 6.0  to 9.5.

         (English units)   pounds per million sq  ft
                           	per operation	

Copper                 32.7                16.4
Nickel                 32.7                16.4
Cr,Total               32.7                16.a
CrVI                    3.3                  1.6
Zinc                   32.7                16.4
CN,Total               32.7                16.4
CNrA                    3.3                  1.6
Fluoride            1308                  654
Cadmium                19.2                  9.6
Lead                   32.7                16.4
Iron                   6!>.4                32.7
Tin                    6!i.4                32.7
Phosphate              65.4                32.7
TSS                 130IJ                  654
pH                 Within the range 6.0  to 9.5.

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         Table 1 - BPCTCA Limitations
     for Electroplating of Precious Metals
                  Subcategory
Effluent                      Effluent
Characteristic                Limitations

                   Maximum for      Average  of daily
                   any one day      values for thirty
                                    consecutive days
                   	      shall  not  exceed

          (Metric units) milligrams  per square meter
                        	per  operation

Ag
Au
CN,A
CN,Total
Cr,Total
CrVT
Ir
Os
Pd
Pt
Rh
Ru
Phosphate
TSS
pH                      Within  the  range  6.0  to 9.5,

        (English units)    pounds per  million  square
                           	feet per operation

Ag
Au
CN,A
CN,Total
Cr,Total
CrVI
Ir
Os
Pd
Pt
Rh
Ru
Phosphate
TSS
                        Within  the  range  6.0  to 9.5.
16
16
16
160
160
16
16
16
16
16
16
16
320
6400
8
8
8
80
80
8
8
8
8
8
8
8
160
3200
3.3
3.3
3.3
32.7
32.7
3.3
3.3
3.3
3.3
3.3
3.3
3.3
65.4
1308
1.6
1.6
1.6
16.4
16.4
1.6
1.6
1.6
1.6
1.6
1.6
1.6
32.7
654

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facility.  Additional techniques for water  recovery  should
come  from  the broad scientific and engineering base in the
United States, although it is  difficult  to  pinpoint  what
specific technologies will be most widely used in 1983.

New TSource Performance Standards

Recommended  standards  of  performance  applicable  to  new
sources discharging to navigable waters  are  summarized  in
Table   2.    The  limitations  are  applicable  to  sources
constructed  after  publication  of   proposed   regulations
prescribing  a  standard  of  performance.   The  new source
performance standards are based on an average water  use  of
80  1/m.   per  operation  as  it  is possible to design and
economically install in-process systems that can be operated
with a lower water use than can be achieved in many existing
plants.

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            Table 2 - NSPS Limitations
       for Electroplating of Common  Metals
                   Subcategory
Effluent                     Effluent
Characteristic               Limitations
                  Maximum for      Average of daily
                  any one day      values for thirty
                                   consecutive days
                                   shall not exceed
(Metric units) milligrams per square meter
per operation
Copper
Nickel
Crr Total
CrVI
Zinc
CN, Total
CN,A
Fluoride
Cadmium
Lead
Iron
Tin
Phosphate
TSS
pH
(English

Copper
Nickel
Cr, Total
CrVI
Zinc
CN, Total
CN,A
Fluoride
Cadmium
Lead
Iron
Tin
Phosphate
TSS
PH

80
80
80
8
80
80
8
3200
48
80
160
160
160
3200
Within the range
40
40
40
4
40
40
4
1600
24
40
80
80
80
1600
6.0 to 9.5.
units) pounds per million square
_ feet per
16. 4
16. 1
16. a
1.6
16.4
16.4
1.6
654
9.6
16.4
32.7
32.7
32.7
654
Within the range
7
operation
8.2
8.2
8.2
0.8
8.2
8.2
0.8
327
4.8
8.2
16.4
16.4
16.4
327
6.0 to 9.5.


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           Table 2  -  NSPS  Limitations
     for Electroplating  of Precious Metals
                 Subcategory
  Effluent
  Characteristic
       Effluent
                    Maximum for
                    any one day
             Average  of daily
             values for thirty
             consecutive days
             shall not  exceed
           (Metric units)     milligrams  per  sq  m
Ag
Au
CN,A
CNr Total
Cr,Total
CrVI
Ir
Os
Pd
Pt
Rh
Ru
Phosphate
TSS
PH
8
8
8
80
80
8
8
8
8
8
8
8
160
3200
4
4
4
40
40
4
4

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FOOTNOTES FOR TABLES 1 AND 2


(a)   The effluent limitations and standards  of  performance
are  defined  as  the  weight  of  pollutant  in  milligrams
discharged per square meter per operation  (Ibs  per  million
sq  ft  per operation).  An operation is defined as any step
followed by a rinse in the electroplating process in which a
metal is electrodeposited on a basis material.  In  Subparts
A  and  B  the electroless plating on non-metallic materials
for the purpose of providing a  conductive  surface  on  the
basis   material,   past   plating   steps   of  chromating,
phosphating and coloring forming an  integral  step  in  the
electroplating   line   and  stripping  where  conducted  in
conjunction with electroplating for the purpose of salvaging
improperly plated parts  may  be  included  under  the  term
"operation"   for   the   purpose   of  calculting  effluent
discharges.  The term "sq m"("sq ft") sahll  mean  the  area
plated expressed in square meters  (square  feet).

 (b)   Single-Day  Maximum  is  the maximum value for any one
day.

 (c)  Thirty-Day Average is  the  maximum   average  of  daily
values for any consecutive 30 days.

 (d)   Total  metal   (in solution and in suspended solids) in
sample.

 (e)  Chromium  (total) is the sum of hexavalent and trivalent
chromium, in solution and in suspended  solids.

 (f)  Oxidizable cyanide is defined as all  detectable cyanide
amenable to oxidation  by  chlorine  as  described  in   1972
Annual  Book  of  ASTM  Standards, 1972, Standard D 2036-72,
Method B, p. 553.

 (g)  Total cyanide  is  defined  as all detectable  cyanide  in
the  sample  following  distillation according to methods of
analyses as set forth  in  HO  CFR  401.

 (h)  Total suspended solids  retained by a   filter   according
 to standard analytical  procedures.

 (i)   A  pH  in   the  range   of  8  to 9  is  the best  range for
minimizing  the   soluble   metal   concentration  during    co-
 prec ipita ti on.

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                        SECTION III

                        INTRODUCTION
Purpoge uand Authority

Section  301 (b)  of  the Act requires the achievement by not
later than July 1, 1977, of effluent limitations  for  point
sources,  other   than publicly owned treatment works, which
are based on the application of the best practicable control
technology currently available as defined by the Administra-
tor pursuant to Section 304(b) of the Act.   Section  301(b)
also  requires  the  achievement  by  not later than July 1,
1983, of effluent limitations for point sources, other  than
publicly  owned  treatment  works,  which  are  based on the
application of the best  available  technology  economically
achievable  which will result in reasonable further progress
toward the national goal of eliminating the discharge of all
pollutants, as determined  in  accordance  with  regulations
issued  by  the  Administrator pursuant to Section 304 (b) to
the Act. Section 306 of the Act requires the achievement  by
new  sources  of a Federal standard of performance providing
for  the  control  of  the  discharge  of  pollutants  which
reflects the greatest degree of effluent reduction which the
Administrator   determines  to  be  achievable  through  the
application  of  the  best  available  demonstrated  control
technology,   processes,   operating   methods,   or   other
alternatives,   including  where  practicable,   a   standard
permitting no discharge of pollutants.

Section  304(b)  of  the  Act  requires the Administrator to
publish within one year of enactment of the Act, regulations
providing guidelines for effluent limitations setting  forth
the  degree  of  effluent  reduction  attainable through the
application of the best practicable control technology  cur-
rently  available  and  the  degree  of  effluent  reduction
attainable through  the  application  of  the  best  control
measures   and   practices  achievable  including  treatment
techniques, process  and  procedure  innovations,  operation
methods  and  other  alternatives.  The regulations proposed
herein set forth effluent limitations guidelines pursuant to
Section 304(c) of the Act for the electroplating category.

Section 306 of the Act requires  the  Administrator,  within
one  year  after a category of sources is included in a list
published pursuant to Section 306 (b) (1) (A) of  the  Act,  to
propose   regulations   establishing  Federal  standards  of
performance for new sources  within  such  categories.   The
                              11

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Administrator  published  in the Federal Register of January
16, 1973 (38 FR 1624), a list of 27 source categories.

Publication of the  list  constituted  announcement  of  the
Administrator's  intention  of  establishing,   under Section
306, standards of  performance  applicable  to  new  sources
within  the electroplating subcategory of the electroplating
industry  which  was  included  within  the  list  published
January 16, 1973.

Summary of Methods Used for Development of the Effluent
Limitation Guidelines and Standards of Performance

The   effluent   limitations  guidelines  and  standards  of
performance  recommended  herein  were  developed   in   the
following  manner.   The electroplating industry was a major
point source reviewed first for  subcategorization  for  the
purpose  of  determining  whether  separate  limitations and
standards  would  be  appropriate  for  different  segments.
Phase  I of the program was limited to the electroplating of
copper, nickel, chromium, and zinc on ferrous and nonferrous
or  combination  thereof,  materials  and   the   associated
preplating  and  postplating  operations.  Phase II - common
metals subcategory has  been  expanded  include  tin,  lead,
aluminium,   cadmium  and  iron.   Phase II - precious metals
subcategory applies to the electroplating of  silver,  gold,
platinum, rhodium, osmium, palladium, iridium and ruthenium.
Such  subcategorization  was  based  upon raw material used,
operations  employed,   and  other  factors.   The  raw-waste
characteristics  were  identified  by analyses of the source
and volume of water used in the  process  employed  and  the
sources  of  waste and waste waters in representative plants
and the constituents of all waste waters.

The full range of control and treatment  technologies  along
with  their  existing problems, limitations, and reliability
and cost and  energy  reguirements  were  identified.   This
included in-plant and end-of-process technologies,, which are
existent  or  capable  of  being designed for waste control.
The quantity and the chemical and  physical  characteristics
of  each  pollutant were identified as well as the reduction
associated with the application of each of the treatment and
control technologies.   In  addition,  the  nonwater  quality
environmental impact,  such as the effects of the application
of   such   technologies   upon  other  pollution  problems,
including air, solid waste, and noise were also identified.

The information, as outlined above, was  then  evaluated  in
order to determine what levels of technology constituted the
"best  practicable  control technology currently available".
                               12

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the "best available technology economically achievable", and
the  "best  available   demonstrated   control   technology,
processes,  operating  methods,  or other alternatives".  In
identifying  such  technologies,  the   factors   considered
included  the  total  cost  of  application of technology in
relation to the effluent reduction benefits to  be  achieved
from  such  application, the age of equipment and facilities
involved, the process employed, the engineering  aspects  of
the  application  of various types of control techniques and
process  changes,  nonwater  quality  environmental   impact
(including energy requirements), and other factors.

Sources  of  information utilized for developing the data in
this document include the following:

       (1)  Published literature (References appear in
           Section XIII)
       (2)  Trade literature
       (3)  EPA Technology Transfer Seminar on Upgrading
           Metal-Finishing Facilities to Reduce Pollution,
           Braintree, Massachusetts, October 30-31, 1973
       (H)  Three EPA regional offices and eight state
           pollution abatement offices
       (5)  Representatives of approximately 75 companies
           with facilities for electroplating who returned
           mailed questionnaires and who were subsequently
           contacted by telephone or further correspondence
           in many cases.
       (6)  Representatives of  17 companies who were visited
           by BCL staff for development of detailed data
       (7)  Analytical verification of effluent data for
           13 plants engaged in electroplating processes.

The decision as to which companies to contact was  a  matter
of  judgement  combined  with  information  from  the  prior
sources  listed.  A plant or company was contacted  if  there
was  any evidence  that  it  was  engaged  in  any  of  the
electroplating  processes  of  interest  and  that  it   was
treating the  wastes  from  these  processes.   Plants were
identified and contacted over a period  of  approximately  3
months,  after  which  further  activity  of  this  sort was
minimal  and most  effort  was  devoted  to  summarizing  the
information  that  had  been  obtained.   Thus,  a number of
plants   were  identified  that  could   be   classified   as
exemplary.

General  Description of the Electroplating Industry

The   electroplating   industry,  as  included  in  Standard
Industrial Classification  (SIC) 3U71,  is  defined  for  the
                                13

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purpose  of  this  document  as  that  portion  of  industry
applying  coatings   on   surfaces   by   electrodeposition.
Pretreatment   of   the  basis  material  and  post  plating
operations  are  included  and  are  carried  out  by   both
independent  (job) platers and captive facilities associated
with  product  fabrications  and  assemblies.   The   annual
dollars    added    value    by    electroplating    exceeds
$2,000,000,000.  Approximately 20,000 companies are  engaged
in  electroplating  and metal finishing.  Of these, 3400 are
job shops supplying only plating services.  About 25 percent
of this segment  is  concentrated  in  the  middle   western
states  of Illinois, Michigan, and Ohio.  Another 20 percent
is concentrated in eastern  Pennsylvania  and  the  Atlantic
coastline states of Connecticut, Rhode Island, New York, and
New  Jersey.   The  location  of  captive plating facilities
follows  the  same  general  geographic  pattern.   Of   the
multimillion  dollar  added value, the 3241 companies in SIC
3471 accounted for $574,800,000 and the value  of  shipments
was $791,100,000 in 1967.  In 1947, there were approximately
1,800 job shops, in 1963, 3,000 and 1974, 3,400.

Electroplating  facilities  of  the  kind  in  SIC 3471 vary
greatly in size and character from one plant to another.   A
single  facility  for  plating  individual  parts  formed by
stamping, casting, machining„ etc., may  employ  plating  or
processing  solutions  (excluding  water  rinses) ranging in
total volume from less than 380 liters  (100 gallons) to  132
liters   (500  gallons).   The  area  of  the  products being
electroplated in these facilities varies as  much  as  three
orders  of  magnitude from less than 10 to more than 1000 sq
meters/day  (100 to 10,000 sq ft/day).  The power consumed by
a single facility varies from a few kilowatt-hours/day to as
much as 20,000 kilowatt-hours/day.   Products  being  plated
vary  in  size  from less than 6.5 sq cm  (1 sq inch) to more
than 1 sq meter (10 sq ft) and in weight from less than 30 g
(1 oz) to more than 9000 kg (10 tons).  Continuous strip and
wire are plated in some plants on a 24-hour/day basis.  Some
companies have capabilities for electroplating ten or twelve
different metals and alloys, but others specialize  in  just
one  or  two.  Because of differences in character, size and
processes, few or no similar plants  exist  at  the  present
time.   Construction of facilities have been custom tailored
to the specific needs of each individual plant.

The  energy  consumed  by  industry  in  the  electroplating
subcategory  was  estimated  to be 1.7 x  109 kilowatt hours.
It also cites  that  from  90,718  to  108,861  metric  tons
(100,000  to  120,000  short  tons)  of  metal   (principally
copper, nickel, zinc, and tin)  are  converted  annually  to
electroplated  coatings.  The figures for sheets, strip, and
                                14

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wire  include  nonelectropiated  coatings,  applied  by  hot
dipping.   All the aluminum is applied by hot dipping, as is
about 90  percent  of  the  zinc,  as  are  significant  but
unidentified percentages of the tin and lead.

These coatings provide corrosion protection, wear or erosion
resistance,   antifrictional   characteristics,   lubricity,
electrical conductivity,  heat  and  light  reflectivity  or
other  special  surface  characteristics,  which  enable the
industry to conserve several millions of  tons  of  critical
metals.    In   the   finishing   of   individual  products,
electroplated coating thickness usually ranges  from  0.0006
to  0.004  cm  (0.00025 to 0.0015 inch), but thicker coatings
to 0.025 or 0.04 cm  (0.010  or  0.015  inch)  are  sometimes
required  for  special engineering purposes or for salvaging
worn or mismachined parts.  Tin and chromium  coatings  from
0.3  to  1  mm (1 x 10-« to a x 10~5 inch) and 0.003 mm (1 x
10~7 inch)  thickness respectively are applied to  continuous
steel  strip  as  a prefinish before coating with an organic
material by the container industry.

An electroplating process includes cleaning, electroplating,
rinsing, and drying.  The cleaning operation consists of two
or more steps that are required for  removing  grease,  oil,
soil,  and  oxide  films  from  the  basis metal surface and
insuring good electroplate adhesion.  Sequential  treatments
in   an   alkaline   solution  and  an  acid  solution  with
intermediate rinsing are the minimum  number  customary  for
these  purposes.   In the electroplating solution, metal ions
in either acid, alkaline or neutral solutions are reduced on
cathode surfaces, which are  the  workpieces  being  plated.
The  metal  ions  in solution are usually replenished by the
dissolution of metal from anodes in bar  form  or  in  small
pieces contain in inert wire or expanded metal baskets.   But
replenishment with metal salts is also practiced, especially
for  chromium plating.  In this case, an inert material must
be  selected  for  the  anodes.    Hundreds   of   different
electroplating solutions have been adopted commercially, but
only  two  or  three  types are utilized widely for a single
metal or alloy.  Cyanide solutions are popular  for  copper,
zinc,  brass,  cadmium,  silver  and  gold, for example, yet
noncyanide alkaline solutions  containing  pyrophosphate  or
another chelating agent have come into use recently for zinc
and  copper.   Acid sulfate solutions also are used for zinc,
copper, tin and nickel, especially  for  plating  relatively
simple   shapes.     Cadmium   and   zinc   are   also  being
electroplated  from  neutral  or  slightly   acid   chloride
solutions.
                              15

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Barrel plating is used for small parts that tumble freely in
rotating  barrels.   Direct  current  loads  up  to  several
hundred amperes are distributed to the parts  being  plated.
Parts may be rack plated by attaching them to plastic coated
copper  frames  designed  to  carry current equally to a few
hundred small parts, several medium-sized shapes or  just  a
few  large products through spring-like rack tips affixed to
the rack splines.  Racks fabricated for manual transfer from
cleaning, plating, and rinsing tanks usually contain .5 to 1
sq m (5 to 10 sq ft) . Larger racks for holding heavier parts
are constructed for use with mechanical hoist  and  transfer
systems.   Mechanized  transfer systems for both barrels and
racks, which  range  in  cost  from  $50,000  to  more  than
$1,000,000  are  being  utilized  for high-volume production
involving six to  thirty  sequential  operations.   In  some
instances, dwell time and transfer periods are programmed on
magnetic  tape or cards for complete automation.  Facilities
for plating sheets will be in the higher end  of  this  cost
range.

Continuous  strip  and  wire  plating facilities cost in the
multimillions of dollars.  A single tin  plating  line  will
electroplate  139 to 186 sq im/min (1500 to 2000 sq ft/min of
steel strip.
                               16

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                         SECTION IV

                  INDUSTRY CATEGORIZATION
Introduction

This  section  discusses  in  detail  the   scope   of   the
electroplating  industry.   The  rationale  is developed for
considering  the  electroplating  industry   as   a   single
subcategory  for  the  development  of  effluent limitations
guidelines and standards of performance.

Objectives of gategorization

The primary purpose of industry categorization is to develop
quantitative   effluent   limitations   and   standards   of
performance  for  discharge of pollutants that are uniformly
applicable to a specific category or subcategory.  This does
not preclude further classification within  a  category  for
the purpose of monitoring to insure compliance.

Electroplating  is  one  of several processes in the broader
category of metal finishing.  It is listed  under  SIC  3471
(Standard   Industrial  Classification  Manual)  along  with
numerous  other  metal  finishing  processes.    The   metal
finishing   industry   was   divided   into   two  segments,
electroplating and metal  finishing,  for  the  purposes  of
developing effluent limitations guidelines.  Phase I covered
the  electroplating  of copper, nickel, chromium and zinc or
combination thereof.  Phase II covers  tin,  lead,  cadmium,
iron,  silver,  gold, platimun, palladium, rhodium, iridium,
ruthenium, titanium, or any combination  thereof.   It  also
covers  stripping.   This  addition is justified because all
electroplating shops have a stripping line to salvage poorly
plated or badly corroded parts.  This usually  exists  as  a
separate   line.    Also   considered   are   the   pre  and
posttreatment  operations   of   alkaline   cleaning,   acid
pickling,  conversion  coatings,  coloring,  and  descaling.
Although these processes are  not  strictly  electroplating,
they usually form an integral part of an electroplating line
and  therefore  must  be  considered  under  the auspices of
electroplating.  Other metal finishing operations which  are
an  end  unto  themselves  and  stand as a separate line are
considered in  separate  documents.   These  are  anodizing,
immersion plating, chromating, phosphating, chemical milling
and etching.

Profile of production Processes
                                17

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The    electroplating   industry   utilizes   chemical   and
electrochemical operations to effect an improvement  in  the
surface  and  structural  properties  of  metals  and  other
materials.  In practice, the operations are put together  in
sequences   that  become  the  processes  which  effect  the
improvement.  Thus, electroplating operations  may  be  both
process and materials oriented.

Those  segments  of  the industry identified in SIC 3471 are
processes performed on products owned  by  a  second  party.
Such  work  is  done  in  job  or  contract shops.  The same
processes may also be performed by  other  manufacturers  of
several  different end products.  These are known as captive
shops.  The processes are the same for both  facilities  and
this document is applicable to both facilities.

Conceptually, an electroplating line may be broken down into
three   types   of   steps   -  pretfeatment  involving  the
preparation of the metal for plating, actual application  of
the electroplate, and post treatment steps.

Pretreatment

Pretreatment  steps  involve cleaning, pickling, degreasing,
descaling, desmutting, vapor blasting,  surface  activation,
etching,  abrasion  and  bright  dipping.  Plating steps are
strikes and  electroplates,  coatings  and  metal  coloring.
Post  treatment steps are conversion and drying.  Stripping,
while performed  separately,  is  an  integral  part  of  an
electroplating  shop.  It is employed for the reclamation of
badly plated parts.

Cleaning

Cleaning involves the removal of oil, grease and  dirt  from
the  surface  of the basis material.   Cleaning or degreasing
may be accomplished in one of several ways.   These  include
alkaline   electrolytic   (anodic  and  cathodic),  diphase,
emulsion,  soak, solvent, and ultrasonic cleaning.

Alkaline cleaners are the most widely used in preparing  the
basis  material.   A  good  alkaline or soak cleaner must be
soluble in water, wet the surface of the basis material, wet
and penetrate soil, saponify or dissolve oil and greases  or
emulsify  or  suspend  insoluble or nonsaponifiable oils and
greases, prevent formation of calcium and magnesium deposits
from hard water, prevent  tarnish  and  corrosion  of  basis
material,   rinse  freely and minimize foaming.   For possible
compositions of alkaline cleaners, see Chapter  V.   Ferrous
metals and alloys can be cleaned using heavy duty (pH = 12.1
                             18

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   13.5)  uninhibited  alkaline solutions.  Usually, though,
weaker solutions  (pH = 10.5 - 12)  are used to avoid  etching
and   pitting.    When  cleaning  nonferrous  materials,  an
inhibitor must be added to stop the corrosive action of  the
cleaner.

Small   volumes   of  work  are  usually  cleaned  by  hand.
Solutions are applied by brushes,  swabs,  or  cloth.   Parts
may also be immersed in cleaning tanks which may be agitated
or  heated  to  increase  efficiency.  The fastest method of
cleaning  is  by  spraying  the  cleaning  solution  in   an
automatic or semi-automatic washing machine.  The mechanical
force  of  the spray combined with the chemical and physical
action of the cleaning solution increases efficiency.

Electrolytic cleaning is best  employed  when  plating  with
brass,   cadmium,  chromium,  copper,  gold,  lead,  nickel,
silver, tin, and zinc.  The basis metal acts as  either  the
cathode  or  the  anode  and  a low voltage current for each
square foot of metal is passed through the alkaline cleaning
solution.  The generation of gases (H2 at the cathode and O2
at the anode)  cause increased agitation and the  removal  of
soil particles.

Diphase  cleaning is composed of a two layer system of water
soluble and a water insoluble organic solvent.  This set  up
is  particularly  useful  where  soil  removal  requires the
action of water and organic compounds and  when  temperature
may  not  be  elevated.   Usually,  the  organic  solvent is
chlorinated.  Because they are non-flammable and are  denser
than   water,   trichloroethylene,   methylene  chloride,  and
perchloroethylene are in common use.   This is also known  as
solvent  cleaning.   Emulsion  cleaning  uses water, organic
solvents  and emulsifying  agent.

Ultrasonic  energy is finding increased use in the agitation
of cleaning solutions.  Although it  is  more  expensive  to
install,  there  are  substantial savings in labor and time.
It is used to remove difficult inorganic and  organic  soils
from intricate parts.

Descaling

Descaling  involves  the  removal  of  oxide  films  and the
buildup of other contaminants on the surface  of  the  basis
material.    Such   removal   may  be  accomplished  through
mechanical or chemical means.

Pickling
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During the production of metals, oxides build  up  on  their
surface during such operations as heat treating and welding.
Also  rust  may  have  built  up  if  the  part  is not used
immediately.  Acid pickling is used to  remove  these  oxide
films and involves dissolution of oxide scale in an acid.  A
generalized reaction may be written.

         MO2 +2HA    MA2 + H2O
          where  M = metal
                 HA = acid

Sulfuric,  hydrochloric,  phosphoric  and  chromic acids all
find use in  this  regard.   Sulfuric  is  most  often  used
because  it  is the least expensive.  Rates of reactions are
increased by an increase in acid concentration,  temperature
and degree of agitation.

Hydrochloric  acid  is  more  costly  and  there is a fuming
problem.  Nevertheless, many  small  establishments  use  it
because  it  works well without the addition of heat.  It is
also used for light acid dips before plating.

Phosphoric acid  is  intermediate  in  cost,  but  it  forms
phosphates  at  the  surface of the basis material.  This is
desirable if  rust  resistance  is  needed  but  not  if  an
electroplate is to follow.

Mechanical

Removal  of  scale  through  mechanical  means  consists  of
tumbling,   (barrel  finishing),  burnishing,  dry   rolling,
buffing,  deburring,  polishing,  desmutting,  and blasting.
Such  mechanical  treatment  eliminates  or  minimizes   the
pickling to follow.

Activation

Activation  involves  the  elimination of a condition on the
surface of the  basis  material  which  would  preclude  the
adhesion of an effective electroplate.

Bright Dipping

Bright  dipping  is used to impart a shiny, clean appearance
to the basis material.  Solutions are comprised of  mixtures
of  nitric,  sulfuric,  phosphoric, chromic and hydrochloric
acids.

Electroless Plating on Non-Metallic Materials
                                20

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Electroless  plating  on  non-metallic  materials   involves
impregnating the basis material with a metal, usually copper
or  nickel,  to provide a conductive surface.  Table 3 shows
the processes involved in electroless plating  on  plastics.
Tables  4  and 5 give the processes for plating on steel and
other materials.

The most commonly  used  basis  materials  are  steel,  zinc
castings,  brass,  aluminum  and  plastics  such  as ABS and
polypropylene.

Electroplating

This  document  covers  the  electroplating  of  common  and
precious metals and their alloys.

Cadmium Plating

Cadmium   plating  was  first  used  commercially  in  1915,
although laboratory work began  in  1819.   Cadmium  plating
provides  a  corrosion  protective  coating  over  the basis
material.  Iron and steel are  most  commonly  used.   Since
cadmium  is  relatively  high priced, only thin coatings are
applied.  It is sometimes used as an  undercoating  for  Zn.
Cd  plating is often used on parts consisting of two or more
metals to minimize galvanic corrosion.

Cadmium cyanide baths are by far the  most  popular  because
they cover completely and give a dense, fine-grained deposit
which  can  be  made  very  lustrous  by  the  use of stable
brighteners.  Because  of  the  toxicity  of  cyanide,  many
people  have tried to find baths which produce plates of the
same superior quality.  Although success has been limited, a
bath containing fluoroborate in place of  cyanide  has  been
used.

Gold Plating

Gold  has  been  applied  for  decorative purposes since man
first   began   to   leave   traces   of   his   activities.
Electrodeposition  of  gold  began in 1805.  The electronics
industry found that gold was the metal best suited  for  the
specialized   qualities   needed   in  electronic  component
manufacture.   Gold  plated  surfaces   not   only   provide
decorative  finishes  and corrosion protection, but are also
important in providing electrical contact surfaces,  bonding
surfaces and electroformed conductors.

Plating  baths  have been developed for each use.  Of these,
there are four types.  Three of these are  cyanide  baths
                              21

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TABLE 3
PROCESSES FOR ELECTROLESS PLATING ON METALS  AND PLASTICS
Operation
Alkaline clean/rinse
Acid dip/rinse
Zincate/rinse
Activate/ rinse
Catalyze /rinse
Electroless Deposit/rinse
Basis Materials
Iron, Nickel, Cobalt Copper Aluminum
X XX
X XX
X
X
X
X XX

Plastics
X
X

X
X
X

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TABLE 4   PROCESSES FOR PLATING ON STEEL
Tin Lead Cadmium Gold Silver Brass Bronze
Operation Plating Plating Plating Plating Plating Plating Plating
Alkaline clean/rinse
Acid dip/rinse
Neutralizer rinse
1-Strike plate/rinse
2-Strike plate/rinse
Electroplate/ rinse
Conversion coat/rinse
X
X



X
X
X




X

X
X
X


X

X
X



X






X
X
X
X



X

X
X
X
X
X
X

X
X

X

X

X
X
X
X
X
x x

X
X
X
X

X

X
X
X
X

X


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TABLE  5     PROCESSES FOR PLATING ON SUBSTRATE
             MATERIALS OTHER THAN STEEL
Silver Lead
Gold on Gold Alloy Indium
on Nickel on on on
Copper Silver Plastic Aluminum Lead
Operation Substrate Substrate Substrate Substrate Plate
Alkaline clean/rinse
Acid dip/rinse
Neutralizer rinse
Strike plate/rinse
Activate/rinse
Catalyze/rinse
Electroless copper/rinse
Electroless nickel/rinse
Electroplate /rinse
Heat diffusion
X
X
X
X




X

X
X

X




X

X
X
X
X




X

X
X
X

.X
X

X
X

X
X
X

X
X
X

X

X
X

X




X



X

X



X
X
                    24

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unbuffered  alkaline  containing Na or K with pH = 8.5 - 13,
acid buffer with pH = 3 - 6, and a neutral buffer with pH  =
6 - 8.5.  The fourth type of bath is non-cyanide.

Silver Plating

The  first  patent  offered  for plating was for Ag in 1840.
The initial use of silver plating was for decoration.  Today
it is used for ball bearings,  electronic  components,  slip
rings, wave guides and hot gas seals.

The  cyanide  bath is by far the most widely used.  However,
in  recent  years  other  baths  such  as  nitrate,  iodide,
thiourea,  thiocyanate,  sulfamate and thiosulfate have come
into recognition.

Tin Plating

At first, tin coatings were  applied  by  hot  dipping.   In
1930,  electrodeposition  began replacing the hot dip method
and by 1973 almost all tin plate was electrically deposited.

Tin is resistant to corrosion  and  tarnish  is  solderable,
soft  and ductile.  It is used as a coating on food-handling
equipment, refrigerator evaporators, washing machine  parts,
builders1  hardware,  electronic  components,  piston rings,
copper wire, and bearing surfaces.

Tin plating baths may produce either a  bright  or  a  matte
finish.   The three most common baths are alkaline stannate,
sulfate and halogen.

Iron Plating

Iron was  first  electrodeposited  during  World  War  I  on
driving  bands  for shells.  Since iron is very magnetic, it
has been used in the manufacture of induction coils.  It was
used extensively during World War II when Cu and Ni were  in
short supply to make electrotypes.  It has also been used to
cover soldering tips.

There are several difficulties in the maintenance of an iron
plating  line.  Special non-corrosive equipment is needed to
heat and agitate the plating bath.  Also, care must be taken
that the plating solution does not oxidize.   However,  this
may  be  offset by the great abundance and low cost of iron.
Iron may be deposited as a hard  and  brittle  or  soft  and
ductile coat.  It is also corrosion resistant.
                               25

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Almost  all  iron  is plated from solutions of ferrous  salts
and   low  pH's.   The  most  common  plating  baths  contain
sulfate, chloride, fluoroboreite and sulfamate.

Lead  Plating

Lead  was first plated from fluorine acids in 1886.  Lead is
most  resistant to hydrofluoric and sulfuric acids.  Thus, it
is used for protective linings as well as coatings  on  nuts
and   bolts,  storage  battery  parts  and bearings.  Lead is
often an undercoat for indium plating.  Lead-tin  and   lead-
antimony alloys are used.

Fluorosilicate  and  fluoroborate  baths are the most widely
used.  Fluoroborate bath is  more  expensive  but  it   gives
finer grained  denser deposits, adheres better to steel and
will  not decompose as readily.

Indium Plating

Indium plating first came into recognition during World  War
II.   It  is  used  largely  in  the manufacture of aircraft
engine bearings.  Corrosion of the originally plated  Cd-Ag-
Cu  bearings  is  reduced  by  an  indium overlayer and heat
treating.   It is also used in. the electronics industry  as  a
doping  agent  in  the production of transistors.  Indium is
often alloy plated with Cu, Sn, Pb, cd, Zn, Ni,  Bi and Rh.

Initially, indium baths were composed of cyanide and  sugar.
Today  the  sulfate  bath is the most widely used along with
alkaline,  fluoroborate, sulfamate, chloride,  perchlorate and
tartrate baths.

Aluminum Plating

Application of aluminum plating on  a  commercial  basis  is
limited.    It  has  been  used for coating uranium and  steel
strip, electrorefining and electroforming.

Because it is more reactive than hydrogen,  aluminum  cannot
be  plated from aqueous solutions or any solution containing
acidic hydrogens.   Only plating from a hydride bath with the
basic ingredients  of diethyl ether,  aluminum  chloride  and
lithium    aluminum   hydride   has   had   any   commercial
applications.

Platinum Metals Plating

Platinum  metals  include  ruthenium,   rhodium,    palladium,
osmium,    iridium,   and  platinum.   They  are  particularly
                                26

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resistive to oxidation, corrosion and  tarnish.   Since  the
platinum metals are quite expensive, thicknesses are minimal
ranging  from  0.1 urn to 5 urn.  Consequently, concentrations
of the metals in baths are very low.  Plating by replacement
is to be avoided.  Basis materials of more  reactive  metals
are  usually  preplated  with  nickel followed by a precious
meta1 strike.

Post Treatment

Coatings

Coatings  are  produced   by   either   immersion   plating,
chromating  or  phosphating  aluminum,  zinc, (die castings,
hot-dipped or electroplated) , steel, copper,  or  magnesium.
When  applied  to  a  basis  material,  chemical  conversion
coatings comprise an  integral  step  of  an  electroplating
line.  It is for this reason that they are covered under the
electroplating  guidelines.   Ions  in  the  waste water are
reduced to low concentrations by chemical  treatment,  water
use   is  similar  to  that  for  electroplating  processes.
Operations  involved  in   producing   chemical   conversion
coatings are shown in Table 6.

Metal Coloring

Coloring  of  the  basis  metals copper, brass, steel, zinc,
cadmium, silver, and tin, generally involves dissolution  of
part  of  the  basis  metals  to  form an insoluble oxide or
sulfide on the surface.   Zinc  and  cadmium  plate  may  be
chromated  and  colored  with  organic  dyes.   Dyes are not
removed from waste water by chemical treatment, but  may  be
by adsorption techniques, i.e., activated carbon.

Coloring  of  aluminum  involves  inhibition of organic dyes
into a colorless aluminum oxide film produced  by  anodizing
or  chemical  conversion.   The organic dyes may be bleached
from waste water by chemical treatment.  When applied  to  a
basis  material,  metal collorings comprise an integral step
of an electroplating line.  It is for this reason that  they
are  covered under the electroplating guidelines.  Water use
for  metal  coloring  processes  is  similar  to  that   for
electroplating  processes.   Operations  involved  in  metal
coloring are shown in Table 7.

Factors Considered in Categorization

When the nature of the industry and the operations performed
were  analyzed,  consideration  was  given  to  the  further
                               27

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                TABLE  6
 PROCESSES FOR CHEMICAL CONVERSION COATINGS
    Operation
                                                    Basis Metal
Steel
                                         Zinc
            Aluminum
             Steel
                                                                                Tin
Alkaline clean/rinse




Acid dip/rinse




Desmut/rinse




Phosphate/rinse




Chromate/rinse
X   X




X   X









X   X




    X
X  X




X  X









X




X  X
X




X




X




X




X
X




X
          X
                                          28

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                TABLE   7     PROCESSES FOR METAL COLORING
Operation
Copper   Brass   Silver   Steel   Tin   Zinc  Cadmium  Aluminum
Alkaline clean/rinse
Acid dip /rinse
1-Cbloring solution/rinse
2-Coloring solution/rinse
Fixing solution/rinse
Brush
Chromat-e solution/rinse
Organic 
-------
categorization  of electroplating processes according to one
or more of the following:

      (1)  Type of basis material
      (2)  Product design
      (3)  Raw materials used
      (U)  Size and age of facility
      (5)  Number of employees
      (6)  Geographic location
      (7)  Quantity of work processed
      (8)  Waste characteristics
      (9)  Rack plating versus barrel plating
      (10) water use
      (11) Treatment technology
      (12) Processing differences.

Type of Basis Material

The wastes produced by processing all common basis materials
are similar.   A  single  facility  can  process  all  basis
materials  without  significant  change in the raw materials
consumed  or  the  waste-treatment  technique  adopted   for
control  of  end-of-pipe  water  discharge.   Any  materials
dissolved from the surface of:  the  customary  basis  metals
during  processing are removed from waste water discharge by
the chemical treatment processes described in  Section  VII.
Furthermore,  the basis materials selected for most consumer
products frequently are interchanged from one model year  to
another.   Therefore,  the  type  of basis material does not
constitute a basis for subcategorization.

Product Design

Product design concepts for minimizing electroplating  costs
also  reduce  wastes  created  by  electroplating processes.
Furthermore, the in-process controls and rinsing  techniques
described in Section VII for minimizing the wastes generated
by  electroplating processes have been adopted for canceling
the effect of the shape factor.  Therefore,  product  design
variance is not a basis for subcategorization.

Raw Materials Used

Raw  materials do not provide a basis for subcategorization,
because practical waste-treatement technology identified  in
Section VII is applicable to all of the usual procedures and
solutions  described  previously for electroplating.  In any
facility carrying out one or more of  the  processes  shown,
the  same  waste  treatment needs arise.  Such variations as
                                30

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exist for each operation are not unique and  do  not  affect
the waste-treatment technology and control.

Size and Age of Facility

The  nature  of electroplating is the same in all facilities
regardless of size and age.  For example, copper plating  is
technically  the  same  in  190  liters  (50 gallons), as in
19,000 liters (5000 gallons), or larger installations.   The
age  of  the  facility does not alter this situation.   Other
electroplating operations follow the  same  pattern.   Thus,
the characteristics of the waste will be the same for plants
of  all ages and sizes.  Only the quantity of waste per unit
time will differ.  Yet, this  factor  is  not  a  basis  for
subcategorization,  because  waste discharge after treatment
is  directly  proportional  to  the  size  of  the  facility
expressed  as  surface  area  processed  per unit time.  The
guidelines recommended in this document provide for variable
production  volume  with  no  need  to  differentiate  plant
capacity as a subcategory.

It    is   recognized   that   some   small   electroplating
installations may have insufficient space for  accommodating
effective  inprocess  controls  for minimizing water use and
conventional  chemical  waste  treatment   equipment.     The
capital  investment  for installing waste control facilities
may  be  greater  for  small  companies  relative  to  their
investment  in  the remaining production facilities than for
larger plants.  In such cases, heavy metal pollutants can be
adsorbed on resins in small  ion-exchange  units  available.
At least one vendor of such equipment will replace the resin
beds,  back  wash  the used beds in their own facilities and
regenerate the resins for reuse.  Alternatively, both  local
and  regional  organizations equipped with large tank trucks
supply a hauling and treating service in several areas.   It
is  also  possible that a small electrodialysis system would
provide recycling of cyanide.  Costs depend on water  volume
and the concentration of pollutants.

Based  upon  data  contained  in  the  Economic  Analysis of
Proposed Guidelines and a report prepared by Booz-Allen  and
Hamilton,     Inc.,    three    alternative    non-automated
establishment size groups were considered in developing  the
general  variance  for  small platers, 1-4 man shop, 5-9 man
shop, and  10-19  man  shop.   It  was  concluded  that  few
independent  shops  with less than 10 employees could afford
to install physical-chemical treatment.  While it  was  also
apparent  that  a  significant  number of shops in the 10-20
employee size group would face adverse impacts  due  to  BPT
requirements,  the pollution potential created by granting a
                               31

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variance to this size group was felt to be larger  than  the
benefits  of  alleviating the adverse economic impact.  This
flow could be expected to contain 2.0 kg/day  (H.U  Ibs/day)
of  each  metal  plated  and total cyanide.  A total flow of
400,000 I/day (100,000 gal/day)  could be discharged  from  a
shop   in   this  size  category.   Hence,  after  extensive
deliberation the variance was established at the 10 employee
size level.

Number of Employees

The number of employees engaged in electroplating  does  not
directly  provide  a  basis  for  subcategorization  because
electroplating operations can be carried out manually or  in
automatic   machines  which  greatly  conserve  labor.   For
example,  an  operation  with  3800  liter   (1000   gallon)
processing   tanks   may  require  six  people  if  operated
manually, whereas a plant of the same tank size and carrying
out the same operations in an automatic machine  would  need
only  two  people.   The  same  amount  of  waste  would  be
generated in each case if the  products  being  plated  were
equal  in total area.  Other examples could be cited to show
that no basis exists for relating the number of employees to
the electroplating processes carried out and  to  the  waste
that  results from those processes.  However, it is believed
that  one  can  relate  the  number  of  employees  to   the
production capacity of a non-automatic facility.

Geographic Location

Geographic  location  is  not a basis for subcategorization.
No condition is known whereby the choice  of  electroplating
processes  is  affected  by  the  physical  location  of the
facility, except availability of process water.   If water is
not available, no modification of electroplating  procedures
can  compensate  for  this  deficiency.   No  electroplating
facilities would be installed in such a location.  The waste
treatment  procedures  described  in  Section  VII  can   be
utilized  in  any  geographical  area.   In  the  event of a
limitation  in  the   availability   of   land   space   for
constructing  a  waste  treatment  facility,  the in-process
controls and rinse water conservation  techniques  described
in  Section VII can be adopted for minimizing the land space
required for the end-of-process treating facility.  Often  a
compact  package unit can easily handle end-of-process waste
if the best in-process techniques are utilized  to  conserve
raw materials and water.

Quantity of Work Processed
                              32

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Quantity  of  work  processed  is  analogous  to plant size.
Therefore,  the  discussion  about  plant  size  is  equally
applicable   to   the   quantity  of  work  processed.   The
application of the guidelines provides  for  the  production
volume of a particular facility.

Waste Characteristics

The  physical  and  chemical  characteristics  of all wastes
generated   by   electroplating   processes   are   similar.
Specifically,  all  wastes  are amenable to the conventional
waste-treatment technology detailed  in  Section  VII.   The
characteristics of treated waste are the same throughout the
industry.   Thus,  waste characteristics do not constitute a
basis for subcategorization.

Rack Plating Versus Barrel Plating

The choice of rack or barrel methods for plating is based on
the size and quantity of the parts to be processed per  unit
of  time.  Neither of these conditions imposes a significant
technical change in the operations for electroplating.   The
selection is always based on economic considerations because
hand  racking  of  small  parts  is usually more costly than
barrel  processing  in   bulk.    Sometimes   plating   bath
compositions  will be modified by altering the concentration
of solution constituents.  However, the same types of salts,
acids, and additives will be  used.   Thus,  the  impact  on
waste  characteristics  is not changed.  The volume of waste
water  (dragout) is  frequently  greater  in  barrel  plating
operations  but the final effluent quality is not a function
of influent  concentration.   Techniques  are  available  to
reduce  the  rinse  water  volumes  in barrel plating to the
levels of rack plating.  These techniques  are  detailed  in
Section VII.  Therefore, rack plating and barrel plating are
not appropriate subcategories.

Water Use

Water  use  formed  a  major  basis  for the differentiation
between electroplating and other metal finishing  processes.
The  water  use  in 1/sq m and the cumulative percentile has
been plotted in Figure 1.  The median water use value is 120
1/sq m.  However, it is not known  to  what  extent  rinsing
technique  and  product  size  and  shape contribute to this
factor.  Therefore 160 1/sq m is chosen  as  the  water  use
factor to allow for these factors.

Treatment Technology
                               33

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                                                FIGURE 1
                                                  *J 00 tD o
COMMON & PRECIOUS METALS

          l/m2 - op
                                                               M
                                                               o
CO
o
    ju tn  o viooto2
    o o  o oooo
M


§
•&  CJI 01 *^J OOtOO
O  O O O OOO
O  O O O OO O
M    CO
o    o
o    o
o    o
ft  U1
§  i
o  o
U)
                         01
                         o
                        a>
                        o
                        00
                        o
                                                                                                                               0

-------
As  no  peculiarity  exists  between raw materials and waste
characteristics as  a  basis  to  separate  facilities  into
subcategories,  none  exists for treatability of wastes as a
basis for subcategorization.  All of the principal treatment
procedures   and   in-process   controls   are   technically
applicable  by choice for any given waste and all operations
generate the same  type  of  raw  waste  regardless  of  the
facility.

However, due to the high costs of some metals there has been
increasing  impetus  to  recover  and  reuse  them.  This is
almost universally true of the precious metals, silver, gold
and the platinum metals.  It is increasingly  the  case  for
chromium  and  nickel.   Thus,  the  treatment  technologies
employed for the wastes  generated  from  electroplating  of
precious  metals  include electrolytic recovery evaporation,
ion exchange, and segregation and chloride precipitation for
silver.  For this reason, electroplating  of  common  metals
and  electroplating  of  precious metals have been separated
into separate subcategories.

Processing Differences

Although the basic notion of electroplating remains the same
whether plating common or precious metals, there is a  great
difference   in  the  care  with  which  they  are  handled.
Precious metal plating involves more  hand  work.   Precious
metals are far more expensive to purchase which is offset by
greater  worth  per  item.   Also, the volume of business is
much smaller for precious metal plating.  For these reasons,
electroplating  of   common   metals   is   separated   from
electroplating of precious metals.

Categorization Summary

The electroplating industry consists of two subcategories of
the  electroplating point source category for the purpose of
establishing effluent limitations guidelines  and  standards
of  performance.   This subcategorization is based upon water
use   and  differences   in   treatment   technologies   and
processes.
                            35

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                         SECTION V

                   WASTE CHARACTERIZATION

Introduction

Water  flow  and  the  sources,  nature  and quantity of the
wastes  dissolved  in  the   water   during   electroplating
processes  are  described in this section.  Water is a major
material in the electroplating industry  and  is  associated
with  every  process.   Yet,  none  of  the water enters the
products so that it does not directly  add  to  the  product
value.


Characteristics of Waste

Waste   water   from  electroplating  processes  comes  from
cleaning, pickling, plating, etching, etc.,  operations  and
includes  constituents  coming from the basis material being
finished as well as from the components  in  the  processing
solution.   Predominant  among  the waste water constituents
are the metal cations (sometimes complexed as  anions)   such
as copper, nickel, chromium, zinc, lead, tin, cadmium, gold,
silver,  platinum metals, and anions that occur in cleaning,
pickling,  or  processing  baths  such  as  phosphates,  and
chlorides, and various metal complexing agents.

Specific Water Uses

Water is used in the following ways:

      (1)  Rinsing to remove films of processing solution
           from the surface of work pieces at the site of
           each operation
      (2)  Washing away spills in the areas of the
           operations
      (3)  Washing the air that passes through ventilation
           ducts so as to remove spray from the air
           before it is exhausted
      (t»)  Dumps of pretreatment and posttreatment solutions,
      (5)  Rinse water (and dumps) of solutions from
           auxiliary operations such as rack stripping
      (6)  Washing of equipment (e.g., pumps, filters,
           tanks, ion-exchange units)
      (7)  Cooling water used in heat exchangers to
           cool solutions in electroplating processes.
      (8)  Rinsing of activated carbon filters used in most
           decorative plating solutions.
                             37

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Rinsing

A  large  portion (perhaps 90 percent)  of the water usage is
in the  rinsing  operations.  That  used  as  cooling  water
usually  does  second  duty  in rinsing steps.  The water is
used to remove the films of processing  solutions  from  the
surface  of  the  work pieces.  In performing this task, the
water becomes contaminated  with  the  constituents  of  the
operating  solutions  and is not directly "reusable".  Thus,
the cost of water is an operating expense to which is  added
the cost of treating the water  prior to reuse or discharge.
Dilute  water  solutions result from the raw waste from each
operation.   Therefore,  the  location  of  rinse  steps  is
important  relative  to  the  operations  performed  in  the
electroplating process.

Some plants use more water  than  the  minimum  required  to
maintain good quality work, others use a smaller quantity to
achieve  the  same  result.   Figure 2 shows a schematic for
water flow in an electroplating facility.

Spills and Air Scrubbing

The extent of leakage from any source and the magnitude  and
frequency  of spills is directly related to plant management
and operating philosophy.  These sources of  waste  can  and
are  being  minimized  to the level where they can be easily
handled.  As of this date, there is  no  known  relationship
between  these  sources  and  a  unit  of  production or raw
material used.  The water from washing away spills and  from
washing  down  ventilation  exhaust air is added to the acid
alkali stream and then treated.

Dumps

Exhausted or spent operating  solutions  to  be  dumped  are
slowly trickled into rinse water following the operation and
prior to treatment.   Alternatively, the operating solutions,
which  are  much more concentrated than the rinse water, may
be processed batchwise in a  treated  facility.   Subsequent
discussion  of waste treatment of rinse water covers all the
water in the facility.

Water from Auxiliary Operations

Cyanide solutions are used for stripping deposits  and  rack
tips  to  form  cyanide compounds that are not decomposed by
treatment with chlorine,  i.e.,  nickel  cyanide.   However,(
there   are   suitable  alternatives  to  cyanide  stripping
                             38

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                Work flow
FIGURE 2.  SCHEMATIC FLOW CHART FOR WATER FLOW IN CHROMIUM
          PLATING ZINC DIE CASTINGS, DECORATIVE
                          39

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solutions  with  which  the  formation  of  stable   cyanide
compounds can be avoided in many cases.

Washing Equipment

Water  used  for  washing filters, pumps, and tanks picks up
residues of concentrated solutions or salts  and  should  be
routed  to  the  appropriate rinse water stream for chemical
treatment.

Cooling Water

As noted previously, cooling water used in  heat  exchangers
for  cooling  electroplating  solutions  should  be used for
rinsing purposes in the interest  of  conserving  water.   A
further  advantage  of  this practice is that if the cooling
water is contaminated by  the  electroplating  bath  due  to
leaks  in the heat exchanger, the contaminated water will be
subjected to treatment to remove the contaminants before the
water is discharged.
At least 95 percent of the products being electroplated  (or
electroformed) to provide resistance to corrosion, wear, and
other  destructive  forces  are processed in medium sized or
large plants  (4,000 to 5,000 in number) , each  deploying  at
least  11  kg/day  (25  pounds/day)  of raw waste into rinse
water.  The potentially toxic waste in  the  form  of  heavy
metal   salts  and  cyanide  salts  from  these  sources  is
approximately 340,000 kg/day (750,000 pounds/day).  This  is
equivalent  to  about 110,000 kg/day (250.000 pounds/day) of
heavy metal and cyanide ions.

At least 450,000 kg/day (1,000,000 pounds/day)  of acids  are
contributed  to  the  total  waste  by cleaning and pickling
operations that precede electx opiating.  The  proportion  of
phosphates  in alkaline cleaning chemicals is believed to be
25 percent of the total alkalies.

Some of the alkaline solution waste and nearly  all  of  the
acid  solution  waste  contain  metals  resulting  from  the
dissolution of metal products  to  be  plated.    Hence,  the
total  amount  of  waste water constituents generated by the
electroplating industry probably  exceeds  1,350,000  kg/day
(3,000,000 pounds/day).

The   estimated  alkali  load  of  230,000  kg/day   (500,000
pounds/day) and  acid  load  of  450,000  kg/day   (1,000,000
pounds/day)  are  usually  in  about  the same ratio in most
                              40

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  TABLE 8    ESTIMATED DAILY RAW WASTE LOAD OF PRINCIPAL SALTS
             USED IN COPPER, NICKEL, CHROMIUM, ZINC PLATING
             AND RELATED PROCESSES
  Operation
                             Principal Salts
  Identity
kg/day pounds/day
Percent of
Total Salts
Consumed by
  Plating
Copper plating    Copper cyanide,       54,000  120,000
                   sodium cyanide, and
                   copper sulfate
Nickel plating
Nickel chloride and   54,000  120,000
 nickel sulfate
Chromium plating  Chromic acid
Zinc plating
Zinc oxide, zinc
 cyanide, sodium
 cyanide, and
 zinc sulfate
45,000  100,000

68,000  150,000
Zinc chromating   Sodium chromate and
                   sodium dichromate
                       6,800   15,000
                                       227,800  505,000
    13



    17


    13

    23
                         2


                        68
(a)  Data from a survey conducted by Battelle's Columbus
     Laboratories in 1965.
                               41

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                    TABLE  9   WASTEWATER CONSTITUENTS FROM PREPARATION OF METAL BEFORE PLATING
K>
Constituent
Iron, Fe"^
Codmium
Copper
Lead
Tin
Silver
Nickel
Aluminum
Zinc
Silicates
Phosphates
Borates
*V~V
Wetting Agents
Chlorides
Sulfates
Nitrates
Fluoborates
Cyanides

Steel
X





X


X
X
X
X
X
X


X

Copper Lead
Alloys Alloys

X
X
X
X X



X
X X
X X
X X
X X
X X
X X

X
X
Basis Material*
Gold
Silver Alloys


X X


X X
X


X X
X X
X X
X X
X X
X X


X X

Nickel
Silver


X



X

X
X
X
X
X
X
X


X

Aluminum Zinc







X
X X
X X
X X
X X
X X
X X
X X
X


        *  The metal  plated  may  be  considered a basis material due to its presence on rack tips that are
          recycled to  pretreatment operations.  For example, cadmium or lead may appear in wastewater
          constituents for  any  basis metal plated with cadmium or lead.
       **  Wetting agents  are  represented by a variety of organic surface active agents, many of them
          oroprietary.

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                        TABLE 10   PRINCIPAL WASTEWATER CONSTITUENTS IN WASTES
                                   GENERATED DURING PRETREATMENT FOR ELECTROLESS
                                   PLATING ON METALS AND PLASTICS
        Pollutant
        Pollutant
                                                       Copper   Silver   Aluminum   Magnesium   Plastics
 Alkaline Cleaning
   Copper,  Cu+2                                          x
   Iron,  ferrous,  Fe+2          X
   Nickel, Ni+2                         X
   Cobalt, Co+2                                  X
  Aluminum, Al+3                                                            ^
   Magnesium,  Mg+2
   Silicate,  Si03~2             XXXXXX          X           X
                                                                                       X
          -    J o             —                •"•        •"•        A         A          X           A
  Carbonate, C03~^             XXXXXX          X           X
  Phosphate, P04~3             XXXXXX          X           X
  Organics                     XXXXXX          X           X

Acid Dipping

  Iron, ferrous, Fe+2          x
  Nickel, Ni+2                         X
  Cobalt, Co+2                                  X
  Copper, Cupric, Cu+2                                   X
  Silver, Ag+1                                                    x
  Aluminum, Al+                                                             y
  Magnesium, Mg+2                                                                      „
  Chloride, Cl"1                                         x
   Sulfate,  504-^               X       X        X        X
   Nitrate,  NOo"1                                                  Y         Y          v
  Fluoride, F3                                                    X         X          ^
                                                                                       A

Conditioning, Sensitizing,
  Activating

  Zinc,  Zn+2                                                                X          X
  Tin, Sn+2                                                                                        x
  Palladium, Pd+2                                        XX                                X
  Chromate,  Cr03~                                                                                  x
  Chloride,  Cl~                                           XX                                X

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plants (i.e., combined acid/a.lkali  wastewaters  are  mostly
acid).   Assuming  the alkalinity as sodium hydroxide (NaOH)
and     acidity     as      sulfuric      acid      (H2SOU),
combination/neutralization  (about  0.9  kg  NaOH/kg  H2S04)
would indicate a total  net  acid  load  of  350,000  kg/day
(750,000 pounds/day).  Table 8 shows the estimated daily raw
waste  load  of  principal  salts used in electroplating and
metal finishing.

Sources of Waste

Preparation of Basis Metal

Tables 9 and 10 list the waste water constituents  resulting
from  the preparation of metals prior to plating operations.
Acids and alkalis must be  neutralized  prior  to  discharge
into navigable waters.

Alkaline Cleaners

Cleaners  are  made  up  with  one  or more of the following
chemicals regardless of the material  to  be  electroplated:
sodium  hydroxide,  sodium  carbonate,  sodium metasilicate,
sodium phosphate  (di- or trisodium), sodium silicate, sodium
tetraphosphate,  and  a  wetting  agent.   Compositions  for
cleaning  steel  are more alkaline and active than those for
cleaning brass, zinc die castings, and aluminum.  Therefore,
cleaners vary with the type of basis metal being cleaned and
also with the type of soil being removed.

Wastes contain not only the chemicals found in the  alkaline
cleaners  but also soaps from the saponifications of greases
left on the surface by  polishing  and  buffing  operations.
Some  oils and greases are not saponified, but nevertheless,
emulsified.  The raw wastes from  the  basis  materials  and
process solutions for cleaning the work show up in the rinse
waters, spills, dumps of concentrated solutions, wash waters
from  air-exhaust ducts, and leaky heating and cooling coils
and heat exchangers.

Alkaline cleaning of zinc die castings is generally  carried
out  in  a proprietary solution, or a solution such as given
below, under the conditions shown.

    Sodium carbonate         7.5 g/1  (1 oz/gal)
    Sodium hydroxide         7.5 g/1  (1 oz/gal)
    Temperature                93 C  (200 F)
    Time                       30-60 seconds.
                                44

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This cleaned work is rinsed thoroughly and then dipped in  1
to  2  percent sulfuric or phosphoric acid for 15-30 seconds
at  room  temperature  to  assure  neutralization   of   any
remaining alkaline films.  Following another thorough rinse,
it is then chromated.

Conventional  cleaning procedures involving solvent cleaners
or vapor degreasing  are  used  routinely  on  aluminum  for
removal  of  grease  and  other  organic  contaminants.  The
removal of soil from aluminum is most frequently achieved by
using alkaline cleaners,  that  function  by  dissolving  or
dispersing  soils, augmented in some instances by etching of
the metal.   Two  representative  cleaner  formulations  for
aluminum  are shown in Table 11.  The silicate in the second
formulation  works  as  both  a  detergent   and   corrosion
inhibitor;  the  kerylbenzene  sulfonate is a wetting agent.
An etching-type cleaning treatment  may  be  used  prior  to
other  treatments  when  a  mat  or  nonspecular  surface is
desired.  Inhibited nonetching cleaners  are  employed  when
attack  or  roughening  of  the  aluminum  part  surface are
undesirable.  Prolonged operations with aggressive  alkaline
cleaners  such  as  those containing caustic soda frequently
cause the precipitation of a  flocculant  hydrated  aluminum
oxide  which  can  interfere  with  effective rinsing of the
work.  Several additional agents, which contain  gluconates,
citrates,  or  tartrates,  have  been  developed to avoid or
minimize such effects.  These agents  work  by  sequestering
the  hydrated  aluminum  oxide  to  yield  a  more  granular
precipitate which is less likely to cake and responds better
to rinsing.

Aluminum alloys containing copper, manganese, or silicon are
especially susceptible to  smut  on  their  surfaces  during
alkaline  cleaning  operations.  The smut generally consists
of  loosely  adherent,  finely  divided  particles  of   the
aluminum  alloy metals or their oxides.  Table 12 lists some
typical deoxidizing and desmutting treatments for  aluminum.
Nitric acid (Formulation A)  is a general-purpose reagent for
removal of smut from aluminum and other metals.  Formulation
B,  containing  about  75 percent nitric acid and 25 percent
hydrofluoric acid is especially effective in the removal  of
smut formed on high silicon (5 percent or more) alloys.  The
chromic  acid-phosphoric  acid   (Formulation D) mixtures are
generally used for the selective removal  of  oxide  without
significant   attack  of  the  metal  surface.   Proprietary
desmutting and deoxidizing solutions are extensively used.

Alkaline cleaning is generally the most satisfactory  method
for  degreasing  and cleaning magnesium prior to chromating.
Representative alkaline cleaner compositions  and  operating
                              45

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                  TABLE
                                                         ALKALINE CLEANERS FOR ALUMINUM
          Type
                       Composition
Temp, C
  Time
•Ji
cr.     Etching

    Inhibited-
      Nonetching
SC'M"ni "-r^"0*-"  /"Mo^m.^ •  99  R  rr/l  (I. n n7/oa1">
^                 s^^j/ •  *~ "•' ~"  o' ~^  v—-— — / o~ — /
Sodium orthophosphate  (Na3P04'12H20:  22.0 g/1 (2.9 oz/gal)

Sodium carbonate  (Na2C03):  22.5  g/1  (3.0 oz/gal)
Sodium orthophosphate  (Na3PC>4 '12H20:  22.5 g/1 (3.0 oz/gal)
Sodium metasilicate  (Na2Si03.9H20: 15.0 g/1 (2.0 oz/gal)
Kerylbenzene  sulfonate (40%):  2.5  g/1 (0.3 oz/gal)
                                                                                                71-8?
71-82
               As Reoiiired
As Required

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               TABLE  12  REPRESENTATIVE DEOXIDIZING AND DESMUTTING
                          TREATMENTS FOR ALUMINUM
          Formulation
Temp, C
                                                        Time
      Purpose
(A)   Cone.  HNO  (10 to 50% by vol)      Ambient

(B)   75% vol cone HN03                 Ambient

     257o vol HF (48 wt%)

(C)   20 g/1  (2.66 oz/gal) Cr03         88-93

     35 ml/1 85 wt% H3PC>3

(D)   100 ml/I 96 wt% H2S04

     35 g/1   (4.66 oz/gal) Cr03        64-82
             30 to 60 sec

             5 to 10 sec



             2 to 10 min



             1 to 5 min
Smut removal

Smut removal,
especially for high
silicon Al alloys

Oxide removal
Oxide removal
                                         47

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conditions  for  processing magnesium are presented in Table
13.

Pretreatment of copper, copper alloys, and silver is similar
to the procedures described for zinc, cadmium, and aluminum.

Acid Dips

Acid  solutions  are  made  up  from  one  or  more  of  the
following:  hydrochloric  acid,  sulfuric  acid,  phosphoric
acid, fluoboric acid, chromic acid, and  nitric  acid.   The
solution  compositions  vary  according to the nature of the
basis metals, the  type  of  tarnish  or  scale.   The  acid
dipping baths for treating metal substrates prior to plating
usually  have a relatively short life.  When these solutions
are dumped and replaced large amounts of chemicals  must  be
treated or reclaimed.  Water used for rinsing following acid
dipping  collects  impurities,  including  metal  waste from
dragout of acid solutions into the rinse water.

Acid  solutions  used  for  pickling,   acid   dipping,   or
activating  accumulate  appreciable  amounts of metals, as a
result of metal dissolution from  metallic  work  pieces  or
uncoated areas of plating racks that are recycled repeatedly
through  the  cleaning,  acid  treating,  and electroplating
cycle.  The copper (and zinc) accumulate in acid bright  dip
solutions  used  to  prepare  electrical  copper  and  brass
contacts for plating.

The amount of  waste  contributed  by  preplate  preparation
steps  varies  appreciably  from  one  facility  to  another
depending on the substrate material, the formulation of  the
solution  adopted  for  cleaning or activating the material,
the solution temperature, the cycle time, and other factors.
The initial condition of the substrate material affects  the
amount  of  waste  generated  during  preplate treatment.  A
dense, scalefree copper alloy article can be easily prepared
for plating by using a mild hydrochloric acid solution  that
dissolves little or no copper, whereas products with a heavy
scale  require  stronger  and  hotter  solutions  and longer
treating periods for insuring the complete  removal  of  any
oxide, prior to plating.

Deposition and Posttreatment

Table  m  gives  the  principal  waste  water  constituents
present in plating rinse  waters  by  way  of  dragout  from
plating  solutions.   The  major contributions are marked by
"X" and are those elements or ions which are constituents in
a given plating bath.  In many instances a metal  cannot  be
                              48

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                    TABLE 13   REPRESENTATIVE ALKALINE CLEANERS FOR MAGNESIUM
   Type
                                 Bath
                                                                       Procedure
Heavy Duty
  Alkaline
(a)
Sodium hydroxide (NaOH):  15-60 g/1 (2-8 oz/gal)

Trisodium phosphate (Na3P04 •  12H20)  11 g/1 (1-1/2 oz/gal)
            .(a)
Caustic Soakv '  Sodium hydroxide (NaOH): 98 g/1 (13 oz/gal)
Immerse parts 3 to 10 minutes
   in bath at 88-100C; clean
   until no water break occurs
   in rinse; rinse thoroughly

Immerse parts in bath at 88-
   100C; soak for 10-20
   minutes; rinse thoroughly
(a)  Add 0.1 oz soap or wetting agent per gallon if heavy mineral oil films are to be removed.

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                                                      TABLE M.   WASTEWATER CONSTITUENTS FROM PLATING OPERATIONS
P,1W WaH t e-
Constituent
Arro-. ia
A 1 ur. 1 r.um
Antimony
Arn'rn Ic
Cadmium
Cal' lu=
Chro-.ium
Cobalt
Confer
Gallium
Gold
Indium
Irldlum
Iron
Lead
Magnesium
Ma-i/ar e«e
Molybdenum
Klci-el
Palla-Jlun
Platinu-n
Potassium
Rhenium
»h',-l ! i-i
Ruthenium
Selenium
Silver
Sod lum
Tin
Zinc
Acetate
Borate
Cyanide
Phosphate
Fluor Me

Chloride
BronHe
Sulfate
Sulf Ide
Thiosulfate
C 1 1 r i. I e
Sulf ite
Carbonate
Tar t rat t-
Sul fa-ate
Nitrate
f.arbo-. •iluulf id*
Fer ro'-yan ide
phosphorous
Anlr.o nitrite
Organic addition
agents
Topper nn'l Niil'il nti'l Lead and Tin and Gold and Silver and Platinum
Copper Alloys Nickel Alloys Chromium Zinc Cadmium Indium l.rnd Alloys Tin Alloys Cold Alloyti Sllvei Alloys Metals Iron
X X X XXX
X
AX A
A AX
AX AX
X
X X
X A A AX
OX 0 0 X X X 0
AX
X
X X
X
X
OX X XX AX

X
A A X
OX 0 A A X OX 0
X
X
OX OOXXX XX OX

X
A
A A
X OX
ox ooxx x oxxx
X X XX
X X X
X X
xxoxxxx x
OX OOXXX X X OXX
x XX
x x x x
XX X X X X X
X 0 X X X XX
X
XX OX XX X XX
x x
X
X

X XX XX
XX A
XXX X
X
A X

X
X
A AAAAAAA A

Because of the use of acid and/or alkaline dips In the pretreatment  for plating,  basli metal  constituent*  arc  expected  to  also be  present  In  small
la the waste (treaa.
ounts (>10 »g/l)

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plated  directly  onto some basis metals and a precoating or
"strike" is required to achieve adhesion.  An "O" before  an
"X" indicates additional wastes originating from such strike
solutions.   For  example,  silver on brass may be preplated
with copper, and/or  nickel  and  silver  on  steel  may  be
preplated with nickel.  Many plating baths contain metallic,
metallo-organic,   or  organic  additives  to  induce  grain
refining and level and brighten  deposits.   Such  additives
are  generally  present  in a bath at concentrations of less
than 1 percent by volume or weight, and are marked  by  "A".
The  conversion  solutions  are  generally  very  dilute  as
compared  to  concentrations  in  normal   electrodeposition
baths.

Iron Plating

Applications  of  iron  deposits include electroformed parts
such as printing plates and surface-hardened tools, dies and
cylinder   liners.    Iron   is   plated   from    chloride,
sulfate/chloride  and fluoroborate baths with concentrations
of 55 to 110 g/1  (7.5 to 15 oz/gal) of iron.  A most  useful
bath is the one containing 127 g/1 (17 oz/gal) FeCl2 and 111
g/1   (15  oz/gal) CaCl2.  The sulfate/chloride bath contains
up to 20 g/1  (3 oz/gal)  of ammonium chloride in addition  to
250  g/1   (33  oz/gal)  ferrous sulfate and small amounts of
ferrous chloride  (30 g/1 or 4oz/gal).  The fluoroborate bath
contains typically 225 g/1 (30 oz/gal) ferrous fluoroborate,
10 g/1  (1.3 oz/gal) sodium chloride and 22.5 g/1 (3  oz/gal)
of  boric  acid.   The  cathode  current  efficiency for all
solutions is between 95 to 100 percent.

Dragin to rinse water after plating is the major  source  of
waste;  floor  spills  and leakage from filter systems are  a
secondary source.  Fluoborate ions will have to  be  treated
where  such a bath is used.  A small concentration of ferric
ion is present  in  the  sulfate  and  chloride  baths  from
oxidation,  but this generally precipitates in the bath as  a
hydroxide or oxide.

Cadmium Plating

Cadmium deposits are used for preventing rusting of  ferrous
metals.  In some instances they are used as an undercoat for
zinc  plating.   Deposits from the cyanide baths are used on
moving  parts,  such   as   communications   equipment   and
instruments  where  corrosion  products  from a zinc deposit
would be objectionable.  In the  case  of  steels,  hydrogen
embrittlement is a problem with some baths and is avoided by
use of a fluoroborate bath.
                               51

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Cadmium  is electroplated from cyanide solutions, containing
cadmium as oxide  or  cyanide,  sodium  cyanide  and  sodium
hydroxide  or  fluoroborate solutions which are purchased as
liquid   concentrates   containing   cadmium   fluoroborate,
fluoboric   acid,  boric  acid  and  ammonium  fluoroborate.
Brighteners and grain refiners in the cyanide  bath  can  be
metallic,  such  as nickel, cobalt, molybdenum and selenium,
or organic such as gelatin, coumarin, sugars, sulfonic  acid
derivatives,  and aromatic aldehydes.  Licorice is suggested
for use  in  fluoroborate  solutions.   Most  additives  are
proprietary.    The  cyanide  bath  has  the  lower  cadmium
concentration of 26 g/1 (3.5 oz/gal)  with  a  total  cyanide
concentration  nearly  four  times  as  great  as the cadmim
concentration.  The fluoroborate bath contains 95 g/1  (12.6
oz/gal)  cadmium  and  therefore  contributes four times the
amount of cadmium to raw waste than does the  cyanide  bath.
Water  use  may  be further increased because of the greater
viscosity of the fluoroborate baths and the resulting higher
dragout.

The major source of waste is from dragout into rinse waters.
A secondary source can be leakage from filters,  pumps,  and
piping  from  the  cyanide solutions.  Accidental spills and
poor housekeeping may in some instances  lead  to  increased
waste; dumping of cadmium solutions is not practiced.

Lead and Lead Alloy Plating

Lead  and  Lead  alloy  coatings  are  used  to  improve the
solderability and coating properties and performance of such
basis metals as  steels,  copper  and  copper  base  alloys,
aluminum,  and  for  strip  plating  of steel mill products.
They are also applied to copper and copper alloy coatings.

Lead and lead  alloys   (mainly  lead-tin)   are  plated  from
fluoroborate  baths, which are purchased as concentrates and
then  diluted   to   the   desired   strength.    The   lead
concentration  may  range  from  112  to  255  g/1 (15 to 34
oz/gal) free fluoboric acid content from 20 to 45  g/1  (2.5
to  6 oz/gal)  and the boric aicid concentration from 20 to 60
g/1 (2.5 to 8 oz/gal).  Additives, such as glue, resorcinol,
and gelatine are present in small amounts (0.15 to 0.3  g/1)
to  improve  deposit structure, or sometimes hydroquinone is
used in concentrations of 10 g/1  (1.3 oz/gal).

In the alloy baths part of the lead is replaced with tin  in
the   form   of   fluoroborate.    Normally   lead  and  tin
fluoroborate concentrates are purchased separately and mixed
in  the  plant  in  proportions  that  achieve   the   alloy
composition  desired.  The raitio of Pb: Sn may vary from 16:1
                              52

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          to 0.7:1 to deposit alloys containing from 6 to  60  percent
          tin.    The  most  concentrated baths are used for plating on
          wire and strip.

          Cathode current efficiencies are near 100  percent  and  the
          baths  are operated at temperatures between 22 and 38°C  (70-
          100°F).  Continuous filtration of the baths  is  recommended
          and  precautions  should  be taken to collect leaks from the
          filtering systems, as well as accidental spills.   The  main
          source of waste should be dragout of plating bath into rinse
          water.  Spills and leaks constitute secondary sources.

          Tin and Tin Alloy Plating

          Tin  and  tin  alloy  electrodeposits are applied to improve
          solderability,  provide  corrosion   protection   and   give
j         antifriction   properties.    Plating   is  done  on  piston
          cylinders and rings, electrotypes, refrigerator  parts,  and
          kitchen ware.  A large amount of tin is plated on continuous
          strip  and  wire.   Tin-nickel  alloy  deposits  have  found
          application  as  substitutes  for   bright   nickel-chromium
          plating.   A  copper undercoat, deposited from cyanide baths
          is required when tin is to be plated on ferrous metals.  The
          tin-lead alloy is  plated  extensively  on  printed  circuit
          boards.

          Tin  is  deposited  from  both  acid and alkaline solutions.
          Three  types of acid tin baths are used in industry   (1)  the
          sulfate/sulfuric  acid  bath,  (2) the fluoroborate/fluoboric
          acid bath, and   (3)  the  halide  bath.   The  sulfate   bath
          contains  30  g/1   (4 oz/gal) of tin or stannous sulfate, 50
          g/1  (6.7 oz/gal) sulfuric acid or cresol sulfonic acid.  The
          latter reagents inhibit the  oxidation  of  divalent  tin  to
          quadrivalent  tin.   Gelatin is used at a concentration  of  6
          g/1  (0.8 oz/gal) and B-naphthol at a concentration of 1  g/1
           (0.11  oz/gal) .

          The fluoroborate bath is marketed in concentrate form, which
          is  diluted   to concentrations of 8U g/1  (11 oz/gal) of  tin,
          56 g/1 (7 oz/gal) of fluoboric acid, 30 g/1  (4 oz/gal) boric
          acid.  A number of organic additives are present; gelatin is
          used  in concentrations of 6  g/1  (0.8 oz/gal) and  B-naphthol
          at a  low concentration of 1  g/1  (0.11 oz/gal).

          The   halide   bath  consists  of  a  solution of chlorides and
 *         fluorides.  The tin concentration is  approximately   35  g/1
*          (U.6   oz/gal)  and  1.5 g/1  (0.2 oz/gal) of an organic agent
          are added.
                                           53

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The acid baths deposit tin twice as  fast  as  the  stannate
baths, because the valence off tin is two rather than four.

Tin  is present as stannate in alkaline bath compositions in
concentrations from 40 to 160  g/1  (5.3  to  21.2  oz/gal).
Sodium  or  potassium hydroxide concentrations are less than
15 g/1  (2 oz/gal).

Tin-Copper and tin-zinc alloys  are  plated  from  the  same
stannate  formulations,  except  that  part  of  the  tin is
replaced by either zinc or copper  cyanides.   The  relative
amounts  of  each  metal  in  the  baths determine the alloy
composition of the deposits.  Sometimes addition agents such
as gelatin, thiourea or ammonium molybdate.  for brightening
and grain refining are used in small amounts (1 g/1).

The tin-nickel bath is acidic with a pH of 2.5 and  contains
stannous  chloride,  nickel  chloride,  ammonium fluoride or
sodium  fluoride  or  ammonium   bifluoride   and   possibly
hydrochloric acid.  The metal concentrations are 27 g/1 (3.6
oz/gal)  of  tin  and  75  g/1 (10.0 oz/gal) of nickel.  The
total fluoride content is 39 g/1  (5.2  oz/gal).   A  bright
alloy is deposited at 100 percent current efficiency without
the  need  for an addition agent.  The only posttreatment is
"hot-flowing" in hot oil.

The major source of waste for  all  the  tin  and  tin-alloy
baths   is  from  dragout  into  rinse  waters.   Since  the
solutions  are  generally  filtered,  leakage  from   pumps,
filters,  and  piping  could  be a secondary source of waste
together with accidental spills.

Silver Plating

Silver is used for decorative, protective,  and  engineering
coatings.   Thin deposits of 2.5 urn (.0001 inch) and applied
over novelty items, jewelry and lighting fixtures.   Thicker
deposits  of  25  to  50 urn  (.001 to .002 inch) are used for
tableware and hollowware and the  thickest  deposits  up  to
1500   m   (.060   inch)   are   applied  for  bearings  and
electroforms.   Thin  deposits  are  generally  plated  from
dilute  baths.   Concentrated, high-speed baths are used for
plating thicker coatings or electroforms.

Silver plating solutions contain potassium  silver  cyanide,
potassium  cyanide, and potassium carbonate.  The baths vary
in silver concentration from 25 to 75 g/1  (3.5  to  10  troy
oz/gal),  depending  upon  their application.  Modern silver
plating solutions also contain additives  in  small  amounts
for  grain  refining  and  brightening,  which are generally
                               54

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proprietary, i.e., reaction products  of  carbon  disulfide,
ketones,   turkey   red  oil,  potassium  antimony  glycerol
complexes, gluconates or tartrates  of  lead  and  antimony,
ammonium  thiosulfate and wetting agents.  Cyanide solutions
are used for electrorefining silver.

Since  silver  will  precipitate  as  a  loose  deposit   by
immersion  on  metals  to  be  plated,  strike solutions are
generally employed to assure adhesion of the silver  to  the
basis  metal.   Strike  solutions  have  a  very  low silver
content 1 g/1  (0.3 troy oz/gal), but a high cyanide  content
of  75  to  90  g/1  (10  to 12 oz/gal) ; the solution may be
modified by the addition of copper cyanide.   If  silver  is
plated  on  ferrous materials both types of strike solutions
are  generally  used.   For  other  basis  metals  the  type
containing  silver  cyanide  only  is considered sufficient.
When nickelr nickel alloys, or stainless steels are  plated,
precautions  must  be  taken to activate the nickel surface.
This may be accomplished by immersion in  hydrochloric  acid
or  by striking in a Wood's nickel bath which is composed of
250 g/1 (32 oz/gal) nickel chloride and 120 ml/1 (16  oz/gl)
hydrochloric acid.  Stainless steel can also be activated by
an  anodic  treatment  in  sulfuric acid solutions.  In many
instances the parts to be plated are composed of  more  than
one metal, requiring both a copper strike and silver strike,
before silver plating.   Consequently, more process steps are
required  for plating silver than for plating the metals and
alloys discussed  earlier.   This,  of  course,  requires  a
greater use of water for rinsing.

Because  of  the high price of silver, the metal in solution
is generally recovered for refining  and  extra  precautions
are  taken  to avoid spills and leaks.  Dumping of solutions
is not practiced.   The  main  concern,   therefore,  is  the
treatment  of  cyanides  present  in  the  waste.   The bath
additives, cited earlier, are present  in  amounts  of  less
than  10  mg/1  in  the  baths and are present in only trace
amounts in  the  rinse  waters.   Because  silver  tarnishes
readily  in  the  atmosphere,  posttreatments  are sometimes
employed  in  the  form  of  chromate  conversion  coatings.
Tarnished  coatings  are produced on silverware by immersion
in a hot solution of sulfur.  Chromate and  sulfide  present
in rinse waters are removable by chemical treatment.

Gold Plating

Gold  plating  is  divided  into  engineering and decorative
applications.    Engineering  coatings  thicker  than  1   urn
(O.OOOOU   inch)    are   used   for   electronic   switches,
semiconductors,  surfaces  of  improved   solderability   and
                             55

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weldability,  electroformed  shapes.   The  coatings inhibit
galling  and  corrosion,  and  increase   wear   resistance.
Decorative  coatings  are  applied  on jewelry, watches, and
novelty items.  The base metal can be a gold or silver alloy
or gold-filled.  When ferrous and other nonferrous materials
are used an undercoat of copper  and/or  nickel  is  applied
first.

Gold   and   gold-alloys   are   plated   from  (1)  cyanide
formulations,  (2) neutral  electrolytes,  and   (3)  slightly
acidic  baths.   The  deposits  may contain as much as 99.99
percent or as little as 50 percent gold.  Gold plating baths
are generally proprietary.  All baths contain from 4  to  12
g/1   (0.5  to 1.5 troy oz/gal) of gold as an auro-cyanide or
sulfide.  The cyanide formulations  contain  free  potassium
cyanide,  potassium carbonate, and potassium diphosphate all
at a concentration of about 30 g/1  (4  oz/gal) .   The  acid
baths  contain  small  concentrations   (0.1  to  2  g/1)  of
cyanides complexed with approximately 90 g/1 (12 oz/gal)  of
citrates.   A sulfide-sulfate mixture of 150 g/1  (20 oz/gal)
is used in one of the cyanide-free baths.

A number of alloying elements are  used  in  gold  baths  of
varying   concentrations.    In  order  to  obtain  specific
physical  properties  in  gold  deposits,  cobalt,   indium,
antimony,  gallium,  manganese,  and  arsenic are  present in
solution in concentrations from 0.005 to 0.150  g/1   (0.0007
to 0.02 oz/gal) while other metals, such as silver, cadmium,
copper  and nickel can have concentrations from 0.025 g/1 to
3 g/1  (0.003 to 0.4 oz/gal).  These coatings have  also found
application for decorative finishes.

Plating times  for  decorative  coatings  are   comparatively
short being from 5 to 15  seconds for cyanide baths and up to
5  minutes  for  neutral  or acid baths.  Therefore, dragout
rates are high, compared  to the amount  of  metal   deposited,
especially  for the case  of the cyanide bath.   Besides gold,
all the previously listed alloy elements are present in  the
raw   waste.   Cyanide  concentrations   in the  bath can range
from  15 to  30  g/1  (2 to  U o:s/gal) .

Save  rinses are generally used  after  gold   plating.   The
concentrated   rinse  can  be returned to the bath  or  sent to
refiners for the recovery of gold.  The  succeeding   diluted
rinses  can  be  treated  by ion exchange for  metal recovery
before  treatment of the  cyanide.

Platinum Metals Plating
                              56

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Of the six metals  in  the  platinum  group  only  platinum,
rhodium,  and palladium are plated to any extent.  Of these,
rhodium is most often deposited.   Decorative  coatings  for
silverware,  jewelry, and watches are very thin  (0.1 urn) and
are used to prevent tarnish and excessive wear of silver and
to enhance the color of gold and gold-filled products.  When
the basis metal is not a silver or a gold alloy an undercoat
of nickel is generally used.  Coatings 25  urn  thick  (0.001
inch)  are  used  for  wear  and corrosion resistance in the
electronics industry and provide a surface of  high  optical
reflectivity.

Platinum is plated on titanium and similar metals, which are
used   as  insoluble  anodes  in  other  plating  operations
(rhodium, gold).   Electroplated  platinum  is  used  as  an
undercoat  for  rhodium plate.  Ruthenium plating is used on
high intensity arc electrodes to improve electrical contact.
Commercial plating of osmium and iridium are believed to  be
nonexistant.

Rhodium  plating  baths are supplied as phosphate or sulfate
concentrates.   The  only  additions  made  to  the  diluted
concentrate   are   phosphoric   and/or  sulfuric  acids  at
concentrations of 25 to 75 ml (3.2 to  9.6  fl  oz/gal)   per
liter  of  plating bath.  A rhodium concentration of 2.0 g/1
(5 dwt/gal) is used for decorative coatings.   Concentration
is  increased  to  10  to  20  g/1  (25  to  50 dwt/gal) for
achieving thicker deposits.

The platinum content in plating solutions ranges from 2.5 to
10 g/1  (6 to 25 dwt/gal) in the form  of  an  amino  nitrite
complex.   Other constituents are 11 g/1 (1.5 oz/gal) sodium
nitrite and 50 ml/1  (6.U oz/gal)  of  concentrated  ammonium
hydroxide.  Palladium bath compositions are similar to those
for  the  platinum bath discussed above.  Iridium deposition
has been accomplished from chloride or bromide solutions and
from a molten cyanide bath.

Very little, if any, waste from  platinum  metals  baths  is
expected  to  reach the final effluent from a plating plant.
The baths have generally very  small  volumes.   Dragout  is
minimized  by  using  some  rinses which are returned to the
plating baths and minor amounts of metal left in  low  flow-
running rinses are recovered by ion exchange.  Solutions are
never  dumped,  but  are  returned  to  the  refineries  for
recovery of the metals.

Electroless Plating on Non-Ferrous Materials
                               57

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D ^criBtion of the Process.  The term "electroless  plating"
is  used to describe a chemical plating process which can be
operated  continuously  to  build  up  a  relatively   thick
deposit.    The   ability   to   build   up  thick  deposits
distinguishes  electroless  plating  from   other   chemical
deposition   processes,  such  as  immersion  (displacement)
plating, which can produce only thin deposits.    Electroless
plating  occurs by catalysis rather than by interchange with
the basis metal characteristic of immersion processes.

Electroless plating can be  used  for  special  applications
where  conventional electroplating processes are unsuitable.
For  instance,  electroless  plating   can   deposit   metal
uniformly  on  complex  shapes  and  in  deep holes that are
relatively  difficult  to  coat  uniformly  by  conventional
electroplating techniques.

Electroless  plating  is  used  to  deposit metals on molded
plastic parts.   If  desired,  a  plastic  part  with  metal
coating  applied  by electroless plating can be subsequently
plated by conventional electrodeposition techniques.

Solutions have been reported for electroless  deposition  of
the  following metals:  Arsenic, cobalt, copper, gold, iron,
nickel, palladium, and alloys of nickel-cobalt  and  nickel-
iron.   However,  only electroless copper and nickel plating
appear to have achieved commercial applicability.

Preparation for Finishing.  Alkaline cleaning to remove soil
and grease is common practice for plastic  substrates  prior
to  electroless  plating.   Parts  are  soak cleaned without
electrolysis.   Cleaners  contain   silicates,   carbonates,
and/or  phosphates  or  combinations of these.   Although the
solutions are inhibited to prevent etching or pitting of the
basis material, small amounts of basis metals are  dissolved
and  are therefore waste water constituents.  Grease and oil
removed from the basis  material  constituents  and  organic
constituent in the waste water.

Acid  pickling follows alkaline cleaning of basis metals and
the pickling solution may  contain  hydrochloric,  sulfuric,
hydrofluoric  and  nitric  acid.   Some of the base metal is
dissolved by the pickling solution and therefore  becomes   a
waste  water  constituent.  Metals such as copper and silver
require catalysis by dipping in  an  acidified  solution  of
palladium chloride.

Plastics  to be electroless plated are roughened by abrasive
wet blasting or tumbling or chemically  with  chromic  acid.
Roughening  is  followed  by  sensitizing in a strongly acid
                               58

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solution  of  stannous  chloride.   A  further  step  is  to
activate  the  surface  in  an  acid  solution  of palladium
chloride.   Thorough rinsing is required after each step.

Pretreatment.  Plastic substrates  require  conditioning  in
concentrated  chromic acid solution, sensitizing in stannous
chloride solution,  and  activation  in  palladium  chloride
solution before electroless plating.

Electroless   nickel  deposits  spontaneously  on  catalytic
metals such as  iron,  nickel,  and  cobalt  after  alkaline
cleaning and acid dipping.  Metals such as copper and silver
can  be  catalyzed by dipping them into a dilute solution of
palladium chloride to produce a thin  immersion  deposit  of
palladium on the metal surface prior to electroless plating.

Aluminum  and  magnesium  are attacked by electroless nickel
plating  solutions  resulting  in  blistered  deposits.   To
overcome  this  attack, a zincate immersion coating is used.
Alternatively, an  electroless  nickel  solution  containing
fluoride can be used directly on magnesium.

The primary use of electroless copper deposits is to produce
conductive  layers  on  plastic  substrates  such as printed
circuit boards and flexible  circuitry  used  in  electronic
equipment.   It has a very important function in providing a
conductive  path  through  holes  in  double-sided   circuit
boards.   In  the  "additive"  method  of  preparing printed
circuits electroless plating is used exclusively to form and
build up  the  circuit  pattern.   The  volume  of  additive
circuits is growing slowly.  The sensitization operation for
electroless  deposition of copper on plastics is the same as
that used for electroless nickel.

Electrpless Deposition Treatment

There are two distinct types of  electroless  nickel  baths:
 (1)  acid  baths operated at pH  4-7 and  (2) ammoniacal baths
operated at pH 8-11.  The acid baths are more commonly used.
A  variety  of  acid  electroless  nickel  baths  have  been
described.   These  baths  are all based on a composition of
nickel chloride or  sulfate,  sodium  hypophosphite  as  the
reducing  agent, and an organic acid.  The organic acts both
as a buffer to help maintain the pH of the  bath  and  as  a
complexing  agent for the nickel ions in solution.  The rate
of nickel deposition is dependent upon the specific  organic
acid in the bath and its concentration.  Hydroxyacetic acid,
lactic acid, and propionic acid are commonly used.
                               59

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A typical ammoniacal electroless nickel bath contains nickel
chloride,  sodium  hypophosphite,  sodium  citrate, ammonium
chloride,  and  ammonium  hydroxide.   A  variation  of  the
ammoniacal electroless nickel bath is the pyrophosphate bath
containing  nickel  sulfate,,  sodium  hypo phosphite,  sodium
pyrophosphate, and ammonium  hydroxide.   The  pyrophosphate
bath  deposits  nickel  at  a  lower  temperature than other
electroless nickel baths and  at  a  faster  rate  than  the
citrate nickel bath.

Electroless  copper baths contain copper sulfate with either
Rochelle  salt   (sodium   potassium   tartrate)   or   EDTA
(ethylenediaminetetraacetic   acid,   sodium  salt)  as  the
complexing agent and formaldehyde as the reducing agent.   A
major  application  of  electroless   copper   is   in   the
manufacture   of   printed  circuit  boards  for  electronic
equipment.  The electroless copper is deposited on  selected
activated  areas  to  form  the conductive leads between the
electronic components that are subsequently mounted  on  the
board.

Unlike   conventional  electroplating  solutions  which  are
commonly used for  many  years  and  are  seldom  discarded,
electroless  plating  baths  have  a finite life and must be
periodically discarded or recovered when  the  concentration
of  reaction products becomes too great.  For instance, when
the phosphite concentration in an  electroless  nickel  bath
has increased through oxidation of hypophosphite to 1 to 1.5
moles  per  liter,  nickel  ortho-phosphite  will  begin  to
precipitate.  Methods have been developed to periodically or
continuously remove the phosphite.   However,  such  methods
have  been  considered  too  expensive for all but companies
using large volumes  of  solution.   Therefore,  electroless
plating  solutions are either discarded or sent to suppliers
or  other  service  companies  for  recovery.   Where  waste
treatment   is  employed  discarded  solutions  are  usually
trickled slowly into a rinse tank prior to waste treatment.
Post treatment of Electroless Deposits

Posttreatment of electroless deposits, when used, is usually
limited to electrodeposition of metal onto  the  electroless
deposit  as  often  follows  the  metallization of plastics.
Consequently, wastes from treatments  following  electroless
deposition  are  considered  in  the  context of the various
metals  that  are  electrodeposited  onto  the   electroless
deposit.

Posttreatment
                                 60

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Chromating

Chromate  conversion coatings are protective films formed on
metal surfaces.  A portion of the base metal is converted to
one of the components of the film by reaction  with  aqueous
solutions  containing  hexavalent  chromium and other active
organic or inorganic compounds.  Chromate coatings are  most
frequently  applied  to the following metals: zinc, cadmium,
aluminum, magnesium,  copper,  brass,  bronze,  and  silver.
Generally  the  chromating  solution  is acidic and contains
chromic acid or its sodium or potassium  salts,  plus  other
organic  or inorganic compounds as activators, accelerators,
or catalysts.  Although chromate conversion coatings can  be
applied  by  chemical or electrochemical action, the bulk of
the coatings are usually applied by  a  chemical  immersion,
spray  or brush treatment.  Most chromate treatments used in
industry   employ   proprietary   solutions.    With   these
processes, a wide variety of decorative and protective films
ranging  from  colorless  to iridescent yellow, brass, brown
and olive drab can be produced.  The coating appearance will
depend on the basis  metal  and  the  processing  procedures
employed.   Additional  coloring  of  the  coatings  can  be
achieved by dipping the parts in organic dye baths to impart
red, green, blue and other colors.   Besides  their  use  as
protective or decorative films, chromate conversion coatings
are  extensively  employed  to provide an excellent base for
paint and other organic finishes, which do not  adhere  well
to untreated metal surfaces.

Chromate  coatings  are  widely  used  on  aluminum  in  the
aircraft, electronics, and home appliance  industries.   The
process,  being  lower  in cost than anodizing, is generally
employed for applications where the abrasion  resistance  or
highly  decorative  colors  of  anodized  aluminum  are  not
required.  The coatings have good  adhesion  properties  for
subsequent   organic  coatings,  offer  good  resistance  to
corrosion, especially in chloride  environments,  and  range
from  clear  to  yellow, depending mostly on immersion time,
pH,  solution  composition,  and  to  some  extent  on   the
particular aluminum alloy treated.

Bright chromate treatments have advantages over conventional
acid  bright  dips for copper alloys, in that they produce a
passive film and also  a  surface  with  a  high  luster  or
polish.   The chromate film provides good protection against
corrosion and sulfide tarnishing  on  unplated  parts.   The
film also provides a good paint base.

Chromate  coatings  are  applied  to silver electroplates to
prevent sulfide tarnishing using  proprietary  formulations.
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Table  15  lists  the  principal  waste  water  constituents
generated during pretreatment,  coating  and  posttreatments
steps  in  chromating  zinc,  cadmium,  aluminum  and  other
metals.

Chromate conversion coatings are frequently applied to  zinc
or     cadmiumrplated     parts     immediately    following
electrodeposition.  No preparation is  necessary.   In  some
cases,  a  baking  operation  to eliminate hydrogen from the
deposit  is   carried   out   following   electrodeposition.
Alkaline  cleaning  and  an  acid  dip may then be necessary
before chromating.

Zinc and cadmium may be chromated to provide

     (1)  Bright    chromates    on    zinc    and    cadmium
         electrodeposits

     (2)  Colored    coatings    on    zinc    and    cadmium
         electrodeposits

     (3)  Colored coatings on zinc die castings.

The bright chromate treatments impart a high luster to  zinc
or  cadmium  plates  and  also provide tarnish and corrosion
resistance.   The  chromate  treatment  of   electrodeposits
generally  follows  immediately  after the last rinse in the
plating cycle.  The  chromate  bath  for  coating  zinc  and
cadmium  parts  is  an  acid  solution containing hexavalent
chromium, such as chromic acid,  plus  other  inorganic  and
organic compounds to promote or catalyze the reaction.

The  chromate coating solution for aluminum usually contains
hexavalent chromium, a fluoride, and an accelerator, such as
ferrocyanide or ferricyanide.  The pH range is  usually  1.0
to   2.5.   Nitric  acid frequently is added as an acidifying
agent.  The fluoride, in  the  acidified  solution,  is  the
active  reagent;  it  dissolves  the existing oxide film and
reacts with the aluminum.  During the coating process,  some
of   the  hexavalent  chromium  is  reduced  to the trivalent
state, and a gel-like film consisting primarily of  aluminum
and  chromium  chromates  is formed.  As freshly formed, the
gel-like coating is dissolved readily in  nitric  acid.   If
desired,  the yellow chromate can be leached with hot water.
With   aging,  the  film   becomes   insoluble.    For   many
applications,   rinsing  and  drying  complete  the  overall
chromating operation.

Much  of  the  development  work  on  chromate  coatings  on
magnesium  has been carried out by the Dow chemical company.
                              62

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              TABLE 15   CHROMATE COATING OF MAGNESIUM BY
                         THE CHROME PICKLE PROCESS
    Step                    Bath               Procedure or Comments


Cleaning          Alkaline                     Immersion

Rinse             Cold Water                   Rinse thoroughly in
                                               cold running water

Chrome Pickle     Sodium dichromate            Immerse parts 1/2 to
                    (Na2Cr20y • 2^0) :         2 minutes in room
                    180 g/1 (24 oz/gal)        temperature solution.
                  Concentrated nitric          After dip, hold parts
                    acid (to Wt% HNO.,) :        above tank for about
                    187 ml/1 (24 fl oz/gal)    5 seconds.

Rinse             Cold Water                   Rinse thoroughly in
                                               cold running water

Rinse             Hot Water                    Hot water rinse used
                                               to facilitate drying
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Chemical Treatment No. 1, also known as "chrome pickle",  is
the  most  commonly  used  chemical  treatment developed for
magnesium.  It can be used on  all  magnesium  alloys.   The
coatings  have  good  qualities  as a paint base and protect
magnesium parts during  shipment  and  storage.   A  typical
chrome-pickle  procedure  is shown in Table 15.  The coating
appearance is usually mat gray  to  yellow  red,  and  about
0.00006 inch of metal is removed from the magnesium.

The   dichrornate   treatment  (Dow  No.  7)   for  processing
magnesium  alloys  (except  the  thorium  containing  alloy)
produces  a brassy to dark brown film, which provides a good
combination of protective  and  paint-base  qualities.   The
dichromate procedure is described in Table 16.

Generally,   a  cold  rinse  followed  by  a  hot  rinse  to
facilitate drying complete the overall chromating process on
magnesium alloys.

Chromating treatments for copper, copper alloys, and  silver
are similar to those described for zinc and cadmium.

Posttreatment  of  chromated  parts,  when used, can involve
bleaching or dying operations to produce or  impart  special
characteristics to the film.  Clear bright finishes for zinc
and  cadmium  can  be  obtained by bleaching or leaching the
yellow coloring from  the  chromate  film.   Various  mildly
acidic or alkaline aqueous solutions are employed, such as

    (1)   Sodium  hydroxide   23   g/1   (3   oz/gal),   room
         temperature 5 to 10 seconds

    (2)   Sodium carbonate 15 to 23 g/1 (2 to 3 oz/gal) 19 to
         54 C (120 to 130 F)

    (3)   Phosphoric acid, 1.0 ml/1  (.13  fl  oz/gal),  room
         temperature, 5 to 30 seconds.

Dyed coatings can also be applied.

Phosphating

Phosphating  is  the  treatment  of ironr steel, zinc plated
steel, and other metals by immersion in a dilute solution of
phosphoric acid plus other reagents to produce  an  integral
conversion  coating  on the surface.  Phosphate coatings are
used to: (1)  provide  a  good  base  for  paints  and  other
organic  coatings,  (2)   condition  the  surfaces  for  cold
forming operations by providing a base for drawing compounds
and lubricants, and (3)  impart corrosion resistance  to  the
                                64

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                TABLE 16   BICHROMATE PROCESS CYCLE FOR
                           MAGNESIUM ALLOYS
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metal  surface  by  the  coating  itself  or  by providing a
suitable base for rust-preventative oils or waxes.

The amorphous aluminum phosphate films are used  extensively
as  a  base  for  organic  coatings.   Crystalline  aluminum
phosphate coatings are used chiefly  for  paint  bonding  to
aluminum and also to provide lubrication for cold forming.

Commerical  phosphating solutions are frequently proprietary
and  usually  consist  of  metal  phosphates  dissolved   in
phosphoric  acid solutions containing accelerators and other
special reagents to improve bath performance.  Commonly used
accelerators  include  nitrites,  nitrates,  chlorates,  and
peroxides.  Phosphating occurs as follows:

    3Me(H2P04)2 + Fe    Me3 (POU) 2 + FeHPOU + 3H3PC4 + H2

where:

                        Me = Zn, Mn, or Fe.

The  metal  is  provided  by  the basis material or from the
phosphating solution.


Cleaning of iron or steel parts is generally accomplished by
alkaline  cleaning  or  solvent  degreasing.   Pickling   in
phosphoric  acid or other mineral acid solutions is used for
removal of rust or other corrosion products.  Rinsing in hot
water,  or  in  special  activating   solutions,   generally
completes  the pretreatment.   In some instances, cleaning is
carried out simultaneously in the same solution.

The pretreatment procedures for phosphating aluminum  alloys
include  alkaline  cleaning,   and  sometimes acid or caustic
etching, desmutting or  deoxidizing  dips,  along  with  the
attendant  rinses.    These  procedures were described in the
earlier sections of the report dealing  with  anodizing  and
chromating of aluminum.

Table  17 lists lists the principle waste water constituents
generated during  preparation,   coating,   and  posttreatment
operations in phosphating iron, steel, and aluminum.

Zinc  and  iron  phosphate coatings are applied by spray and
immersion techniques.  Parts are immersed in a 2-1/2 percent
by volume zinc phosphate solution at (90 F)  for  30  seconds
or  sprayed  with  a  4  percent  by  volume  zinc phosphate
solution at (140 to 180 F)  for 3 to 5 minutes.   Zn phosphate
may be applied to parts  in  an  automatic  barrel  line  by
                               66

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immersion   in   a   proprietary  solution  containing  zinc
phosphate, phosphoric acid, and nitrates.  Iron phosphate is
applied by immersion in a 5 percent by  volume  solution  at
(125  F  to  160  F) and pH 3.5 to U.5 for 3 to 5 minutes or
spraying with a (1/2 to 2 oz/gal)  solution at (90 to 160  F)
and  pH  3.5 to 5.0 for 1 to 2 minutes.  Manganese phosphate
is applied by immersion in a solution at (200 F)  for  10  to
20 minutes.

A   typical   solution  for  producing  amorphous  phosphate
coatings on aluminum contains 70 g/1 phosphoric acid  and  a
ratio of fluoride ion to chromic acid of 0.25.  The fluoride
removes  the  oxide  film  on  the  surface  and attacks the
aluminum base metal to  provide  the  ions  needed  to  form
aluminum phosphate.  The treatment times for temperatures of
100  to  130  F  vary from a few seconds to several minutes.
The coating weights can be varied from 0.11 to  1.3  g/sq  m
(10 to 400 mg/sq ft) .

Crystalline  phosphate  coatings  on  aluminum  are produced
using  solutions   containing   zinc   or   manganese   acid
phosphates, an oxidizing agen such as nitrate, and a complex
fluoride  to  serve  as  the  activating  agent.   A typical
phosphating solution contains: 0.7  percent  zinc  ion,  1.0
percent  phosphate  ion   (Pcm)3~,  2.0  percent  nitrate ion
(NO31-, and fluoroborate ion  (BFU)»~.  A  satisfactory  film
can  be  produced by spraying solution for 1 to 2 minutes at
SH to 57 C  (130 to  135 F), or by immersing for 5 minutes  in
a solution at 5U to 57 C  (130 to 135 F) .

The  final  rinse after phosphating of iron, steel, and zinc
is usually carried out in  a dilute  chromic  acid-phosphoric
acid  solution   (0.1 percent by volume) .  This rinse removes
unreacted chemicals and improves the corrosion resistance of
the  phosphated  surface.   The  rinse   step  is  frequently
followed by a dip in a suitable oil, wax, or other lubricant
before drying in hot air.

Immersion Plating

Immersion  tin  plating  is  used  to  "whiten" pins, hooks,
eyelets,  screws, buttons,  and other hardware items  made  of
copper,   brass,  or  steel.   In  addition,  aluminum   alloy
pistons for internal combustion engines  are coated  with  an
immersion  deposit  of tin.  All immersion tin plating  baths
for copper, brass,  and steel are based on stannous  chloride
solutions.    Immersion tin solutions contain, in addition to
stannous  chloride,  cream  of tartar   (potassium  bitartrate),
ammonium   aluminum   sulfate,  or  sodium cyanide and  sodium
hydroxide.
                               67

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TABLE 17   PRINCIPAL WASTEWATER CONSTITUENTS IN WASTES
           GENERATED DURING PHOSPHATING OPERATIONS ON
           VARIOUS METALS AND ALLOYS
Basis
Constituent
Preparation-Cleaning
and Activating
Sodium, Na+
Aluminum Al+3
Zinc, Zn+2+2
Iron, Fe+2
Carbonate, C0o~2
Phosphate, P04~3
Silicate, Si02~2
Gluconate
Sulfate
Chloride
Nitrate
Chromate
Titanium, Ti+3
Antimony, Sb+3
Phosphating
Sodium, Na+
Aluminum, A1+3
Zinc , Zn+2
Iron, Fe+2
Manganese , Mn+2
Phosphate, P04~3
Chromate, Cr04~2
Fluoride, F~l
Fluoborate, BF4~1
Nitrite, N02"1
Nitrate, N03"1
Chlorate, C103~l
Posttreatment
Chromate, Cr04~2
Phosphate, P04~2
Metals and Alloys
Iron, Steel, and
Zinc-Plated Steel


X

X
X
X
X
X
X
X
X
X
X
X
X

X

X
X
X
X



X
X
X

X
X

Aluminum


X
X


X
X
X
X
X
X
X
X



X
X
X

X
X
X
X
X

X




Water soluble oils
  and waxes
X
X
                          68

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Copper is immersion deposited on steel wire prior to drawing
in order to reduce wear on the dies.   Copper  is  deposited
from  an  acid copper sulfate solution.  Copper-tin alloy is
obtained on steel wire by adding tin  salts  to  the  copper
sulfate solutions.

Gold  is  immersion  deposited  on  copper and brass to gild
inexpensive  items  of  jewelry.   Typical  immersion   gold
plating   solutions  contain  gold  chloride  and  potassium
cyanide or pyrophosphate.

Nickel is immersion deposited  on  steel  prior  to  ceramic
enameling  to improve the adhesion of the enamel.  Immersion
nickel solutions contain nickel sulfate, or nickel  chloride
and boric acid.

Tables   18  and  19  list  the  principal  constituents  in
wastewater  generated  during  immersion  plating  of   tin,
copper, gold, and nickel on various basis metals.

Metal Coloring

This  section on metal coloring covers only chemical methods
of coloring in which the metal surface is converted into  an
oxide  or  other  insoluble  metal  compound.   Coloring  by
chemical  deposition   (immersion),  electrodeposition,   and
electrolytic conversion are covered elsewhere in this report
and thermal oxidation and lacquering are beyond the scope of
this report.

Metal  coloring  by  chemical  conversion methods provides a
large  group  of  decorative  finishes.   The  most   common
finishes  are  used  on  copper,  steel,  zinc, and cadmium.
Application of the color to the cleaned basis metal involves
only a brief immersion in a dilute  aqueous  solution.   The
colored  films  produced  on the metal surface are extremely
thin and delicate.  Consequently, they  lack  resistance  to
handling  and the atmosphere.  A clear lacquer is often used
to protect the colored metal surface.

Preparation procedures for metal  coloring  are  similar  to
those  used  in the metal finishing processes, consisting of
alkaline cleaning and acid dipping.  In  addition  to  these
operations,  polishing  is  often used to obtain the desired
surface   prior   to   coloring.    Mechanical    polishing,
electropolishing,  and chemical polishing are used singly or
in combination.  Etching and bright dipping are also used to
obtain specific surface  finishes.   If  mechanical  polishing
is  used,  a degreasing operation must be included to remove
the polishing compound.
                              69

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      TABLE 18   PRINCIPAL WASTEWATER CONSTITUENTS IN WASTES
                 GENERATED DURING IMMERSION PLATING OF TIN,
                 COPPER, GOLD, AND NICKEL
Basis Metal
Pollutant
Immersion Tin Plating
Tin
Chloride
Tartrate
Cyanide
Ammonium
Aluminum
Sulfate
Sodium
Immersion Copper Plating
Copper
Sulfate
Brass
X
X
X
X
X
X
X
X


Copper
X
X
X
X
X
X
X
X


Steel
X
X
X
X
X
X
X
X
X
X
Aluminum
X
X








Immersion Gold Plating
  Chloride
  Bicarbonate
  Pyrophosphate
  Cyanide
  Potassium
Immersion Nickel Plating
  Nickel
  Sulfate
  Borate
  Chloride
X
X
X
X
X
X
X
X
X
X
                     X
                     X
                     X
                     X
                                  70

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TABLE 19   PRINCIPAL WASTEWATER CONSTITUENTS IN WASTES GENERATED DURING
           PREPARATION  FOR IMMERSION PLATING ON VARIOUS BASIS METALS
Basis Metal
Pollutant Brass
Alkaline Cleaning
in
Iron, ferrous, Fe *•
+3
Aluminum , Al
Silicate, SK>3~2 X
Carbonate, C03~2 X
Phosphate, P0^~3 X
Organics X
Acid Dipping
Iron, Ferrous, Fe"*"2
Aluminum, Al -^
10
Copper, Cupric, Cu X
Zinc, Zn+2 X
Sulfate, S04~2 X
Chloride, Cl" X
Copper Steel Aluminum
X
X
XXX
XXX
XXX
XXX
X
X
X

XXX
XXX
                                 71

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Table  20  lists  the  principal  waste  water  constituents
generated during pretreatment steps prior to metal coloring.

A  large  amount  of  copper and brass is colored to yield a
wide variety of shades and colors.  Shades of black,  brown,
gray,  green, and patina can be obtained on copper and brass
by use of appropriate coloring solutions.   Table  21  shows
the  constituents  of  the waste water obtained from rinsing
copper and brass after various coloring operations.

The most important colors for ferrous metals  are  based  on
oxides  which  yield black, brown, or blue colors.  Table 22
shows the constituents of the waste water used  for  rinsing
iron and steel after various coloring operations.

A number of colors can be developed on zinc depending on the
length of immersion in the coloring solution.  For instance,
in  a  solution  of  ammonium chlorate the color sequence is
yellow, brown, violet, deep blue, and blue-black.   Ammonium
molybdate  solutions  give  a  gold  to brown to black color
sequence.  Other colors that can be developed  on  zinc  are
listed  in  Table  23,  which also shows the constituents in
water used for rinsing after the coloring operations.

Although cadmium is not a structural metal,  its  use  as  a
protective  deposit  on ferrous metals provides applications
for  decorative  coloring.   The  most   important   surface
treatment for cadmium is chrornate passivation which improves
its  resistance  to  the  atmosphere and to finger prints as
well as providing color.  In most instances,  the  color  of
chromate-passivated  cadmium  is  yellow,  bronze,  or  dark
green.  Black and brown  colors  can  also  be  produced  on
cadmium.  Table 2H lists the principal constituents in waste
waters for rinsing after the coloring operations on cadmium.

Silver,  tin,  and  aluminum  are also colored commercially.
Silver is given a gray color by immersion in  a  polysulfide
solution  such as ammonium polysulfide.  Tin can be darkened
to produce an antique finish on pewter  by  immersion  in  a
solution  of  nitric  acid  and copper sulfate.  Coloring of
aluminum is done by dyeing following anodizing as  discussed
in  the  section  of  this  report on anodizing of aluminum.
Waste water constituents from these processes are  shown  in
Table 25.

Because   the  colored  layers  on  metal  surfaces  are  so
delicate, they are usually protected by a  coat  of  lacquer
applied  by  spraying  or dipping.  When water emulsions are
used, the lacquer or polymer is a waste water constituent.
                               72

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          TABLE 20   PRINCIPAL WASTEWATER CONSTITUENTS
                     IN WASTES GENERATED DURING PRE-
                     PARATION FOR METAL COLORING
                                              Metal Basis
          Pollutant              Copper/Brass   Steel   Cadmium   Zinc

Alkaline Cleaning
                     •4-2
    Iron, Ferrous, Fe                             X
    Cadmium, Cd+2                                          X
    Zinc, Zn+2                                                     X
    Silicate, Si03-2                  X           XXX
    Carbonate, C03~2                  X           XXX
    Phosphate, P04~3                  X           XXX
    Organics                          X           ,X        XX
Acid Dipping
    Iron, Ferrous, Fe+2                           X
    Cadmium, Cd                                            X
    Copper, Cupric, Cu+2              X
    Zinc, Zn+2                        X                            X
    Sulfate, SOA~2                    X           XXX
Electro and Chemical Polishing
    Phosphate, P04~3                  X          XX
    Nitrate, N03*"1                    X
    Acetate, C2H302"1                 X
    Carbonate, C03~^                                       X
    Sulfate, S04~2                                X
                           73

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          TABLE 21   PRINCIPAL WASTEWATER CONSTITUENTS
                     IN WASTES GENERATED DURING
                     COLORING OF COPPER AND BRASS
Pollutant
+2
Copper, Cu
_2
Carbonate, CO,,
+1
Ammonium, NH,
+2
Nickel, Ni
-2
Sulfate, SO,
-1
Chlorate, CIO
-1
Chloride, Cl
+3
Arsenic, As
+3
Antimony, Sb
-2
Thiosulfate, S.O,
2 3
+3
Iron, Ferric, Fe
Nitrate, NO ~
+2
Zinc, Zn
Color
Black Brown Gray Green

XX X

X X

XX X

X X

X

X

X X

X

X

X


X
X

X

Patina

X

X

X







X

X







X


Chlorite, CIO
Acetate,
              -1
               -1
Barium, Ba

Sulfide, S
          +2
-2
                X
X

X
                                                        X
                             74

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   TABLE 22  PRINCIPAL WASTEWATER CONSTITUENTS IN WASTES


             GENERATED DURING COLORING OF IRON AND STEEL
Pollutant
                             Black
                                         Color
                                            Brown
                           Blue
Nitrate, NO




Bichromate,




Nitrite, N02"1




Copper, Cu+2



           4-2
Mercury, Hg




Iron, Ferric, Fe




Sulfate,




Chloride, Cl"1




Thiosulfate,




Lead, Pb+Z




Acetate, C2H302
             +3
            "1
           in

Arsenic, As °





Chlorate, C103





Cyanide, CN"1
           "1
X




X




X
                            X
                                           X
                                              X




                                              X




                                              X




                                              X




                                              X
                                                            X
                             X




                             X










                             X




                             X




                             X




                             X




                             X




                             X




                             X
                       75

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TABLE 23   PRINCIPAL WASTEWATER CONSTITUENTS IN WASTES
           GENERATED DURING COLORING OF ZINC
Pollutant
4-9
Copper , Cu
Chlorate, d03~
Nitrate, N03~
Sulfate, SO^
Ammonium, NH^ •*-
Chloride, Cl"1
Carbonate, C03~2
Nickel, Ni+2
Malybdate, Mo^~
Color
Black Brown Green
XXX
X X
X
XXX
XXX
X
X
X
X X

Blue



X
X


X

                      76

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TABLE 24   PRINCIPAL WASTEWATER CONSTITUENTS IN
           WASTES GENERATED DURING COLORING OF
           CADMIUM
Pollutant
Chromium, Cr+6
Nitrate, W^"1
Copper , Cu
Sulfate, SO^"2
Chlorate, ClOo"-'-
Chloride, Cl"1
Arsenic, As+3
Ammonium, NH/
o
Dichromate, C^Oy *•
Permanganate, Mn04~-'-
Cadmium, Cd+2
Iron, Ferric, Fe+3
Color
Chromate Black Brown
X
X X
X
X
X
X X
X
X
X
X
X
X
                       77

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      TABLE  25  PRINCIPAL WASTEWATER CONSTITUENTS IN WASTES
                 GENERATED DURING COLORING OF SILVER, TIN,
                 AND ALUMINUM
   Pollutant
Gray on
Silver
                                         Color
Antique on
Pewter (Sn)
  Color on
Anodized Al
NH4+

S=

N03~

Cu+

so4=

Organic dyes
  X

  X
                    X

                    X

                    X
                                           X
                                    78

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Water Usaofe in the Electroplating Industry

The 1967 Census of Manufacturers estimated the total  yearly
intake of water to be  3.27 x  10*° liters  (8.7 x 10» gallon).
Of  this  amount  2.78  x 10»o liters  (7.4 x 10« gallon) was
discharged as follows:
2.10 x 10»o liters
6.02 x 109    it
3.76 x 10*    "
7.14 x 10«    "
                      (5.6 x  10« gal) to public sewers
                      (L6 x  1Q9 galj to surface water bodies
                      (1.0 x  10« gal) to ground
                      (1.9 x  10« gal) treated before discharge.
This segment of industry, in 1967, had 55,100 employees,
an  average  of  about  503,840  liters   (134,000  gal)
employee.
                                                        or
                                                       per
Of the firms with captive electroplating facilities, 2191 of
them had a few more than 25,709 total  employees.   However,
the number of employees was not cited where one or two firms
were  present.  At the same water use rate these firms would
discharge over 1.182 x 1Qio liters  (3.144  x  10«  gal)  and
assuming   the   same  average  rate  the  remaining  14,500
companies would discharge over 7.802 x 10^° liters  (2.075  x
10»o
                                79

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                         SECTION VI

             SELECTION OF POLLUTANT PARAMETERS

Introduction

This  section  of  the  report  reviews the waste character-
ization detailed in Section V and  identifies  in  terms  of
chemical  and  physical  constituents that which constitutes
pollutants  as  defined  in  the  act.   Rationale  for  the
selection  and,  more  particularly,  the rejection of waste
water constituents as pollutants are presented.

First,  consideration  was  given  to  the  broad  range  of
chemicals   used  in  the  electroplating  industry.   Those
considered to be amenable to treatment are identified.

Electroplating. Waste Water Constituents

A  large  variety  of  chemicals  that  become  waste  water
constituents  are  used in the electroplating industry.  The
important ones were identified in Section  V.   Not  all  of
these  constituents  will  be found in the waste waters from
every facility, since the number of processes  in  a  single
facility  varies  as  well  as the number of basic materials
pretreated  and  types  of  posttreatment  operations.   The
nonmetallic  cations,  anions  (hydrogen, ammonium, sulfate,
phosphate, chloride, etc.) can be considered typical of  the
electroplating industry.

Each   waste   water   constituent   is   additive   to  the
concentration of that constituent in the raw water supply if
the latter is not deionized.  Sometimes constituents in  the
effluent originate from the raw water supply.

Good  chemical treatment will oxidize over 99 percent of the
cyanide and normally remove 85 to 99 percent of the  metals.
The  other  constituents in the raw waste having much higher
solubilities than metal hydroxides are usually not  removed,
and  contribute to the total dissolved solids of the treated
effluent.

Some soluble constituents  are  adsorbed  on  the  insoluble
material    and    removed    during   clarification.    The
concentrations of total dissolved solids  and  each  soluble
constituent  depend on the degree of water conservation used
in the facility.
                               81

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Waste Water Constituents..and Parameters of Pollutions!
Significance

The waste water constituents of pollutional significance are
total suspended solids, phosphate, oxidizable cyanide, total
cyanide,  fluoride,  cadmium,  hexavalent  chromium,   total
chromium,  copper,  iron,  nickel,  tin, zinc, color and pH.
These constituents are the subject of  effluent  limitations
and standards of performance regardless of the physical form
(soluble or insoluble metal)  or chemical form (valence state
of a metal and whether or not it is complexed).

The pH is subject to effluent limitations because it affects
the  solubility of metallic compounds such as zinc hydroxide
and the soluble metal content of the treated effluent.

Thus, the major chemical,  physical,  and  biological  waste
water    constituents    and   parameters   of   pollutional
significance are as follows

               Total suspended solids

               Phosphate

               Oxidizable cyanide

               Total cyanide

               Fluoride

               Cadmium

               Hexavalent Chromium

               Total Chromium

               Lead

               Iron

               Tin

               Silver

               Gold

               Indium

               Osmium
                                  82

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               Paladium

               Platinum

               Rhodium

               Ruthenium


               pH.

Other waste water constituents of secondary importance  that
are  not the subject of effluent limitations or standards of
performance are as follows

                Aluminum

                Total dissolved solids

                Chemical oxygen demand

                Oil and grease

                Turbidity

                Color

                Temperature

                Ni trate

                Ammonia

RatipnaJ.e for the Selection of Waste Water Constituents
and Parameters

Total Suspended Solids

Suspended  solids  include  both   organic   and   inorganic
materials.  The inorganic components include sand, silt, and
clay.   The  organic  fraction  includes  such  materials as
grease, oil, tar, animal and vegetable fats, various fibers,
sawdust, hair, and various  materials  from  sewers.   These
solids  may settle out rapidly and bottom deposits are often
a mixture  of  both  organic  and  inorganic  solids.   They
adversely  affect  fisheries  by  covering the bottom of the
stream or lake with a blanket of material that destroys  the
fish-food  bottom  fauna  or  the  spawning  ground of fish.
Deposits containing organic  materials  may  deplete  bottom
                              83

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oxygen   supplies   and  produce  hydrogen  sulfide,   carbon
dioxide, methane, and other noxious gases.

In raw water sources for domestic use,  state  and  regional
agencies  generally specify that suspended solids in streams
shall not be  present  in  sufficient  concentration  to  be
objectionable   or   to   interfere  with  normal  treatment
processes.  Suspended solids in  water  may  interfere  with
many  industrial processes, and cause foaming in boilers, or
encrustations on equipment exposed to water,  especially  as
the  temperature rises.  Suspended solids are undesirable in
water for textile industries;  paper  and  pulp;  beverages;
dairy  products;  laundries;  dyeing;  photography;  cooling
systems, and power plants.  Suspended particles  also  serve
as a transport mechanism for pesticides and other substances
which are readily sorbed into or onto clay particles.

Solids may be suspended in water for a time, and then settle
to  the  bed of the stream or lake.  These settleable solids
discharged  with  man's  wastes   may   be   inert,   slowly
biodegradable materials, or rapidly decomposable substances.
While  in  suspension,  they  increase  the turbidity of the
water,   reduce   light   penetration   and    impair    the
photosynthetic activity of aquatic plants.

Solids  in  suspension  are aesthetically displeasing.  When
they settle to form sludge deposits on the  stream  or  lake
bed, they are often much more damaging to the life in water,
and  they  retain  the  capacity  to  displease  the senses.
Solids, when transformed into  sludge  deposits,  may  do  a
variety  of damaging things, including blanketing the stream
or lake bed and thereby destroying  the  living  spaces  for
those  benthic  organisms  that  would  otherwise occupy the
habitat.  When of  an  organic  and  therefore  decomposable
nature,  solids use a portion or all of the dissolved oxygen
available in the area.  Organic materials also  serve  as  a
seemingly  inexhaustible  food  source  for  sludgeworms and
associated organisms.

Turbidity is principally a measure of  the  light  absorbing
properties  of suspended solids.  It is frequently used as a
substitute method of quickly estimating the total  suspended
solids when the concentration is relatively low.

Phosphorus

During  the  past  30 years, a formidable case has developed
for the belief that increasing  standing  crops  of  aquatic
plant growths, which often interfere with water uses and are
nuisances  to  man,  frequently  are  caused  by  increasing
                                84

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supplies of phosphorus.  Such phenomena are associated  with
a  condition  of  accelerated  eutrophication  or  aging  of
waters.  It is generally recognized that phosphorus  is  not
the  sole  cause of eutrophication, but there is evidence to
substantiate that it is frequently the key element in all of
the elements required by fresh water plants and is generally
present in the least amount relative to need.  Therefore, an
increase in phosphorus allows use of other, already present,
nutrients  for  plant  growths.    Phosphorus   is   usually
described, for these reasons, as a "limiting factor."

When  a  plant  population  is  stimulated in production and
attains a nuisance status,  a  large  number  of  associated
liabilities  are immediately apparent.  Dense populations of
pond weeds  make  swimming  dangerous.   Boating  and  water
skiing  and  sometimes  fishing may be eliminated because of
the mass of vegetation that serves as an physical impediment
to such activities.  Plant populations have been  associated
with  stunted fish populations and with poor fishing.  Plant
nuisances emit vile stenches, impart  tastes  and  odors  to
water  supplies,  reduce  the  efficiency  of industrial and
municipal water treatment, impair aesthetic  beauty,  reduce
or  restrict resort trade, lower waterfront property values,
cause skin rashes to man during water contact, and serve  as
a desired substrate and breeding ground for flies.

Phosphorus  in the elemental form is particularly toxic, and
subject to bioaccumulation in much the same way as  mercury.
Colloidal  elemental  phosphorus  will  poison  marine  fish
(causing skin tissue breakdown  and  discoloration).   Also,
phosphorus   is  capable  of  being  concentrated  and  will
accumulate in organs and  soft  tissues.   Experiments  have
shown  that  marine  fish  will  concentrate phosphorus from
water containing as little as 1 ug/1.

Cyanide^ Amenable  to  Oxidation  by.  chlorine.   Oxidizable
cyanide  may  be present in significant amounts in the waste
water from this segment of the electroplating  industry  and
is   amenable   to  oxidation  by  chlorine  under  alkaline
conditions.

Cyanide^_Total

Cyanides in  water  derive  their  toxicity  primarily  from
undissolved  hydrogen  cyanide  (HCN)  rather  than from the
cyanide ion (CN-).  HCN dissociates in water into H+ and CN~
in a pHdependent reaction.  At a pH of 7 or below, less than
1 percent of the cyanide is present as CN-; at a  pH  of  8,
6.7 percent; at a pH of 9, 42 percent; and at a pH of 10, 87
percent  of  the  cyanide  is  dissociated.  The toxicity of
                             85

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cyanides is also increased by increases in  temperature  and
reductions  in  oxygen tensions.  A temperature rise of 10°C
produced a two- to threefold increase in  the  rate  of  the
lethal action of cyanide.

Cyanide  has  been  shown  to  be  poisonous  to humans, and
amounts over 18 ppm can have adverse effects.  A single dose
of about 50-60 mg, is reported to be fatal.

Trout and other aquatic organisms are extremely sensitive to
cyanide.  Amounts as small as .1 part per million  can  kill
them.   Certain  metals,  such  as  nickel, may complex with
cyanide to reduce lethality especially at higher pH  values,
but  zinc  and  cadmium  cyanide  complexes  are exceedingly
toxic.

When  fish  are  poisoned  by  cyanide,  the  gills   become
considerably  brighter  in  color than those of normal fish,
owing  to  the  inhibition  by  cyanide   of   the   oxidase
responsible  for  oxygen  transfer  from  the  blood  to the
tissues.

Fluorides

As the most reactive non-meteil, fluorine is never found free
in nature but as a constituent  of  fluorite  or  fluorspar,
calcium fluoride, in sedimentary rocks and also of cryolite,
sodium  aluminum fluoride, in igneous rocks.  Owing to their
origin only in certain types of rocks  and  only  in  a  few
regions,  fluorides  in high concentrations are not a common
constituent of natural surface waters, but they may occur in
detrimental concentrations in ground waters.

Fluorides are used as insecticides, for disinfecting brewery
apparatus, as a  flux  in  the  manufacture  of  steel,  for
preserving  wood and mucilages, for the manufacture of glass
and  enamels, in chemical industries,  for  water  treatment,
and  for other uses.

Fluorides  in  sufficient guantity are toxic to humans, with
doses of 250 to 450 mg giving   severe  symptoms  or  causing
death.

There  are  numerous  articles  describing  the  effects  of
fluoride-bearing waters on dental enamel of children;  these
studies  lead  to  the  generalization that water containing
less than 0.9 to 1.0 mg/1  of   fluoride  will  seldom  cause
mottled  enamel  in children,, and for adults, concentrations
less than 3 or U  mg/1   are  not  likely   to  cause  endemic
cumulative   fluorosis   and    skeletal  effects.   Abundant
                                86

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literature is also available describing  the  advantages  of
maintaining  0.8  to  1.5  mg/1  of fluoride ion in drinking
water to aid in the reduction of  dental  decay,  especially
among children.

Chronic fluoride poisoning of livestock has been observed in
areas   where  .water  contained  10  to  15  mg/1  fluoride.
Concentrations of 30 - 50 mg/1  of  fluoride  in  the  total
ration  of  dairy  cows  is considered the upper safe limit.
Fluoride from waters apparently does not accumulate in  soft
tissue  to  a  significant degree and it is transferred to a
very small extent into the milk and to  a  somewhat  greater
degree  into  eggs.   Data  for  fresh  water  indicate that
fluorides are toxic to fish at  concentrations  higher  than
1.5 mg/1.

Cadmium

Cadmium in drinking water supplies is extremely hazardous to
humans,  and  conventional  treatment,  as  practiced in the
United States, does not remove it.  Cadmium is cumulative in
the liver, kidney, pancreas, and thyroid of humans and other
animals.  A severe bone and kidney  syndrome  in  Japan  has
been  associated  with  the  ingestion  of  as little as 600
ug/day of cadmium.

Cadmium  is  an  extremely  dangerous  cumulative  toxicant,
causing  insidious progressive chronic poisoning in mammals,
fish, and probably other animals because the  metal  is  not
excreted.   Cadmium could form organic compounds which might
lead to mutagenic or teratogenic effects.  Cadmium is  known
to   have  marked  acute  and  chronic  effects  on  aquatic
organisms also.

Cadmium acts synergistically with other metals.  Copper  and
zinc   substantially  increase  its  toxicity.   Cadmium  is
concentrated by  marine  organisms,  particularly  molluscs,
which  accumulate  cadmium  in calcareous tissues and in the
viscera.  A concentration factor of 1000 for cadmium in fish
muscle has been reported, as have concentration  factors  of
3000  in  marine  plants, and up to 29,600 in certain marine
animals.  The eggs and larvae of fish  are  apparently  more
sensitive  than  adult  fish  to  poisoning  by cadmium, and
crustaceans appear to be more sensitive than fish  eggs  and
larvae.

Chromium

Chromium,  in  its  various  valence states, is hazardous to
man.  It can produce lung tumors when  inhaled  and  induces
                               87

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skin   sensitizations.    Large   doses  of  chromates  have
corrosive effects on the  intestinal  tract  and  can  cause
inflammation  of  the kidneys.  Levels of chromate ions that
have no effect on man appear to be so  low  as  to  prohibit
determination to date.

The  toxicity  of  chromium salts toward aquatic life varies
widely with the species, temperature,  pH,  valence  of  the
chromium,   and   synergistic   or   antagonistic   effects,
especially that of hardness.  Fish are  relatively  tolerant
of  chromium  salts, but fish food organisms and other lower
forms of aquatic life  are  extremely  sensitive.   Chromium
also inhibits the growth of algae.

In  some  agricultural  crops,  chromium  can  cause reduced
growth or  death  of  the  crop.   Adverse  effects  of  low
concentrations  of chromium on corn, tobacco and sugar beets
have been documented.

Lead

Lead  is  a  cumulative  poison  to  the  human  system  and
concentrates   itself   primarily  in  bones.   Symptoms  of
advanced lead poisoning  are  anemia,  abdominal  pain,  and
gradual  paralysis.   Immunity  to lead does not develop but
reaction grows more acute.  It is not an elemental essential
to the metabolism of animals.

Lead poisoning has been reported in  humans  drinking  water
with  a  concentration  as  small  as  0.0H2 mg/1.  However,
concentrations of 0.16 mg/1 seem to have had no effect  over
long  periods.  It is generally felt that 0.1 mg/1 can cause
poisoning if ingisted regularly.

Chronic lead poisoning among  animals  has  been  caused  by
concentrations less than 0.18 mg/1.  Changes have been noted
in  nervous  systems  of  laboratory rats after ingistion of
0.005 mg/ per kg of body weight.

Lead concentrations of approximately of 0.5 mg/1  appear  to
be the maximum safe limit.

Studies  on  the effect of lead on fishes indicate that lead
reacts with  an  organic  constituent  causing  a  mucus  to
obstruct  the  gills  and body.  The fish ultimately dies of
suffocation.  Concentrations between 0.1 mg/1 and 0.41  mg/1
have  resulted  in  a TL 50 within HQ hours to sticklebacks,
guppies, minnous, brown trouts and coho salmon.

Silver
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Silver may be found  occurring  naturally  in  the  elementl
state  as  aggentite, Ag2S, proustite, Ag3AsS3, horn silver,
AgCl, and pyrargyrite, Ag3SbS3.

Although silver is harmful to  humans  only  in  very  large
doses,  very  small amounts have proved toxic for fish.   The
uthal concentration for sticklebacks was  0.003  mg/1.   The
average  survival  time  at 0.004 mg/1 was one week, at 0.01
mg/1 was four days and at 0.1 mg/1 was one day.  For  salmon
fry silver nitrate was definitely toxic at 0.44 mg/1.

For  Daphnja  and  Mjcroregma  the  median  threshold effect
occurred at  0.03  mg/1  of  silver.   For  one  species  of
flatworm it occurred at 0.15 mg/1.

Gold

Gold is widely distributed in trace amounts in rocles, aris,
and  sea  water.  The pure metal is extremely unreactive and
insoluble.  Gold has  not  been  found  to  the  harmful  to
humans, but the lethal concentrations to the stickleback has
been reported as 0.40 mg/1.

Iron

Iron  in small amounts is an essential constituent to animal
diets.  The daily nutritional requirement is 1-2 mg and most
people intake an average of 16 mg.  However, drinking  water
becomes umpalatable at approximately 1.0 mg/1.  Ferrous iron
imparts  as  taste  at 0.1 mg/1 and ferric iron at 0.2 mg/1.
It  also   tends   to   precipitate   causing   stains   and
discoloration  of  water.   For these reasons drinking water
limitations have been recommended at 0.1 mg/1.

Very high concentrations of iron have been  toxic  to  fish.
Iron  hydroxides have been known to precipitate on the gills
of fish causing obstruction.  Also heavy  precipitation  may
smother eggs.

Tin

Tin  is  not  a  nutritional  requisite  but neither does it
appear harmufl to human or animal life.   The  average  diet
contains  17.14  mg/day.  Very large doses of 30-50 mg/kg of
body weight caused much  loss  of  weight  in  cats.   Trace
amounts of tin appear beneficial to some fish.

oH, Acidity and Alkalinity
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Acidity  and  alkalinity  are  reciprocal terms.  Acidity is
produced  by  substances  that  yield  hydrogen  ions   upon
hydrolysis  and  alkalinity  is  produced by substances that
yield hydroxyl ions.  The terms "total acidity"  and  "total
alkalinity" are often used to express the buffering capacity
of  a  solution.   Acidity  in  natural  waters is caused by
carbon dioxide, mineral acids, weakly dissociated acids, and
the salts of strong acids and  weak  bases.   Alkalinity  is
caused  by strong bases and the salts of strong alkalies and
weak acids.

The term pH is a logarithmic expression of the concentration
of hydrogen ions.  At a pH of 7, the hydrogen  and  hydroxyl
ion  concentrations  are  essentially equal and the water is
neutral.  Lower pH  values  indicate  acidity  while  higher
values indicate alkalinity.  The relationship between pH and
acidity or alkalinity is not necessarily linear or direct.

waters  with  a  pH  below  6.0 are corrosive to water works
structures,  distribution  lines,  and  household   plumbing
fixtures  and  can  thus  add  such constituents to drinking
water as iron, copper, zinc, cadmium and lead.  The hydrogen
ion concentration can affect the "taste" of the water.  At a
low pH water tastes  "sour".   The  bactericidal  effect  of
chlorine  is  weakened  as  the  pH  increases,  and  it  is
advantageous to keep the  pH  close  to  7.   This  is  very
important for providing safe drinking water.

Extremes  of  pH  or  rapid  pH  changes  can  exert  stress
conditions  or  kill  aquatic  life  outright.   Dead  fish,
associated  algal  blooms,  and  foul stenches are aesthetic
liabilities of any waterway.   Even  moderate  changes  from
"acceptable"  criteria  limits of pH are deleterious to some
species.  The relative toxicity  to  aquatic  life  of  many
materials   is   increased  by  changes  in  the  water  pH.
Metalocyanide complexes  can  increase  a  thousand-fold  in
toxicity  with  a drop of 1.5 pH units.  The availability of
many nutrient substances  varies  with  the  alkalinity  and
acidity.  Ammonia is more lethal with a higher pH.

The   lacrimal   fluid   of  the  human  eye  has  a  pH  of
approximately 7.0 and a deviation of 0.1 pH  unit  from  the
norm   may   result  in  eye  irritation  for  the  swimmer.
Appreciable irritation will cause severe pain.
Rationale for the Selection_of^Total Metal as a Pollutant
Parameter for ElectroBlating^Processes
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Chemical treatment as presently developed is able to  reduce
the concentration of metals in solution to low values and to
remove  the  precipitated form of the metal (clarification).
There is no a priori reason  why  soluble  metal,  insoluble
metal, complexed metal, etc., should be regarded as separate
pollutant  parameters in view of the fact that technology is
capable of reducing the total metal content to low values.

It is practical, as part of chemical  treatment,  to  remove
insoluble   metal   precipitate   from   the   effluent   by
sedimentation,  clarification,  filtering,  or  centrifuging
prior to the discharge of liquid effluent to streams.  Large
amounts  of  metal  hydroxides  in  the  streams are further
sources of metal ions if  the  water  later  becomes  acidic
relative  to  the  pH  at  which  the  metal hydroxides were
originally precipitated.   If  this  happens,   the  original
purpose in precipitating hydroxides is defeated.  Therefore,
removal   of  precipitated  metal  hydroxides  by  efficient
clarification  prior  to  discharge  of  the   effluent   to
navigable waters is assumed.

With  removal  of  total  suspended solids to levels of less
than  50  mg/1,  significant  removal  of  metal  hydroxides
occurs.  However, some portion of the total suspended solids
contains metals either as metal hydroxides or adsorbed metal
ions.    Regardless  of  the  form,  the  metal  content  of
suspended solids represents a significant pollutant  in  the
water.

Metals  are  considered  pollutants regardless of form.  The
standard  method  of  analysis  for  total  metal   involves
acidification  of  the  sample  to  analyze  for total metal
content (dissolved metal plus any metal in suspended  solids
left  from  clarification).  For the purpose of establishing
effluent limitations and  standards  of  performance  it  is
herein   specified,   in   the  absence  of  any  qualifying
statement, that the  concentration  of  metals  in  mg/liter
means  total  metal,  as  analytically  determined  by  acid
digestion prior to filtering.


Rationale for Rejection of Other Waste Water Constituents as
Pollutants for Subcategory (1) Processes

Metals

than those described as a pollutant above is based on one or
more of the following reasons:

       (1)   They are not normally present in the processing
                             91

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           solutions used in the electroplating
           industry.  It would be redundant to
           make a long list of materials that
           can be controlled but that are not
           present.

      (2)   Insufficient data exist upon which
           to base effluent limitations and
           standards of performance.   Waste-
           water constituents such as sodium,
           potassium, nitrate and ammonia are
           present in many processing solutions
           and waste waters, but there is no
           practicable method at present of
           removing them from solution.

Dissolved Solids

Dissolved solids are not a significant  pollution  parameter
in  this  industry.   Although  the  concentration  of total
dissolved solids will become higher as efforts are  directed
to reducing water use and volume of effluent discharged, the
total quantity of dissolved solids will remain unchanged.

Chemical Oxygen Demand

The  chemical oxygen demand can be significant in some cases
because of the oil and grease removed from the work  in  the
cleaning  operation,  which  then  constitutes a part of the
cleaner when it is  dumped.   It  is  possible  to  minimize
chemical oxygen demand in some cases by use of organic vapor
degreasers prior to alkaline cleaning.  However, if there is
a  high  chemical  oxygen  demand  practicable technology to
lower it has not been  demonstrated  in  the  electroplating
industry.

Biochemical Oxygen Demand

Biochemical  oxygen  demand  is  usually  not  an  important
pollution parameter in this subcategory.  An  electroplating
plant  in  a suburban location not discharging to a publicly
owned system  must  treat  its  own  sanitary  sewage  in  a
separate  treatment  facility.   If the plant chooses to mix
the treated sanitary effluent with process wastes  prior  to
treatment BOD would be considered a major parameter.

Turbidity

Turbidity    is    indirectly    measured   and   controlled
independently by the limitation on suspended solids.
                              92

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Temperature

Temperature  is  not  considered  a  significant   pollution
parameter  in this subcategory.  However, cooling water used
to cool process tanks and/or  evaporative  recovery  systems
that  are  not  subsequently  used for rinsing could contain
pollutants from leaks in the system.

Aluminum

Aluminum may be present in significant amounts in the  waste
water  stream.   Limits  are  not placed on aluminum at this
time due to insufficient data.  However, it is believed that
significant removal will result when  conventional  chemical
treatment techniques are employed.
                              93

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                        SECTION VII

              CONTROL AND TREATMENT_TECHNQLQGY


Introduction

The  control  and  treatment  technology  for  reducing  the
discharge of pollutants from  electroplating  operations  is
discussed in this section.

In  process controls of electroplating waste waters included
material  substitutions, good  housekeeping  practices,  and
water   conservation   techniques.    The  in-plant  control
techniques discussed are generally considered to  be  normal
practice in these industries.

Chemical  treatment  technology  is  discussed first in this
section because some treatment of this type is  required  of
many  waste  waters  generated  by electroplating operations
before discharge into  navigable  streams.   After  chemical
treatment  the  amount of pollutants discharged to navigable
waters is  roughly  proportional  to  the  volume  of  water
discharged.

Advanced  treatment  of  electroplating waste water includes
techniques for the removal of pollutants and techniques  for
the  concentration   of  pollutants  in the waste waters for
subsequent removal by treatment or  recovery  of  chemicals.
Although  all  of  the treatment technologies discussed have
been applied to waste waters from electroplating  processes,
some may not be considered normal practice in this industry.

The  proper  design, operation, and maintenance of all waste
water control and treatment systems are considered essential
to an effective waste management program.  The choice of  an
optimum  waste  water  control  and treatment strategy for a
particular electroplating facility requires an awareness  of
numerous  factors affecting both the quantity of waste water
produced and its amenability to treatment.

Possible Treatment Designs

Continuous Treatment.  The chemical treatment process may be
made continuous by  (1) sizing and baffling  treatment  tanks
to  provide  sufficient  hold  times  to  complete  chemical
reactions;  (2) providing continuous  monitoring  of  pH  and
oxidation/reduction  potentials  and controls for regulating
reagent additions  by  means  of  these  monitors;  and   (3)
                              95

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providing  a  continuous  overflow settling tank that allows
sludge to be pumped off periodically through the bottom.

A flow diagram for a  large  continuous-treatment  plant  is
shown in Figure 3.  The dilute acid-alkali stream originates
from  rinses  associated  with alkaline cleaners, acid dips,
and  baths  containing  metal  ions,  but  no   cyanide   or
hexavalent  chromium.   When  concentrated  acid  and alkali
baths are to be discarded they are transferred to a  holding
tank  and  added  slowly  to  the  dilute  stream.   In this
manner,  sudden  demands  on  the  reagent   additions   and
upsetting  of  the  treatment  conditions  are avoided.  The
dilute acid-alkali stream  first  enters  a  surge  tank  to
neutralize  the  waste  water  and  equalize the composition
entering the precipitation tank.  The hexavalent chromium is
reduced at a pH of 2.0 to 2.5, and the addition of  the  SO2
and  HCl are controlled by suitable monitors immersed in the
well-agitated reduction tank.  Cyanide  is  destroyed  in  a
large tank with compartments to allow a two-stage reduction.
Reaction time is about 3 hours.

The  treated  chrome,  cyanide,  and neutralized acid-alkali
streams are run into a common tank where pH is automatically
adjusted to optimize the precipitation of metal  hydroxides.
The  stream  then  enters a solids contact and settling unit
where  mixing,  coagulation,  flocculation,   recirculation,
solids  concentration, sludge collection, and sludge removal
are accomplished.  Flocculants are  usually  added  to  this
tank.   The  overflow from the settling unit constitutes the
discharge from the plant. The sludge  may  be  dewatered  by
filtering and the filtrate returned to the settling unit, if
the  solid  content  of  this  filtrate  is  higher than the
overflow from the clarifier.

Integrated  Treatment.   The  integrated   system   uses   a
reservoir  tank in conjunction with the rinse tanks for each
type of plating  bath.   A  common  solution  is  circulated
through  the  chemical  wash  tank  (which  replaces what is
normally the first  rinse  tank)  and  the  reservoir.   The
solution  contains  an excess of treatment chemical so that,
for example, cyanide destruction takes  place  in  the  wash
tank  and  directly  on the film of dragout  solution on the
part itself.  Therefore, no  cyanide  is  dragged  into  the
subsequent  rinse  tank and the effluent requires no further
treatment for cyanide.

Because metals are precipitated separately at  a  relatively
high  concentration,  the  metal  hydroxide  settled  in the
reservoir may be recovered, dissolved, and returned  to  the
plating bath from which it originated.  In contrast to batch
                              96

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             strong
vo
                                                                                                        1.8 gpm
                                                                                                     sludge
                            FIGURE 3 DIAGRAM OF A TYPICAL CONTINUOUS-TREATMENT PLANT

-------
 and   continuous   treatments, which  are generally carried out
 in a  separate  facility,   the  reservoir  in  the  integrated
 system  is  in  proximity to the plating room because of the
 necessity for  circulation.   The  layout  of  an  integrated
 system for treating  rinse water waste from a cyanide plating
 solution and a chromium plating bath is shown in Figure H.

 Batch Treatment

 The batch method is  generally used  for small or medium-sized
 plants.  Batch treatment  is useful  not only for rinse waters
 but    for   expendable  process  solutions  containing  high
 concentrations of chemicals  or  spills,  leaks,  or  other
 accidental  discharge  of process  solutions.  Holding tanks
 collect  the waste water and  are  large  enough  to  provide
 ample time to  treat, test, and drain a tank while another is
 being filled.  Analytical tests are made before treatment to
 determine  the  amount of reagent to add and after treatment
 to establish that the desired effluent  concentrations  have
 been   obtained.   A flow diagram for batch treatment is shown
 in Figure 5.

 Chemical Treatment Technology

 Applicability

 Chemical  treatment   processes   for   waste   water   from
 electroplating    facilities   are   based   upon   chemical
 precipitation reactions,  many of which have been known since
 the beginning  of modern chemistry over 200 years ago.  These
 reactions have been used  as the basis  for  the  design  and
 engineering  of   systems  capable  of  treating  waste water
 containing a large variety of pollutants  and  reducing  the
 concentration  of  metals  below 1 mg/1.   Control procedures
 have  been  devised  to   assure  the  effectiveness  of  the
 processes.
Cy.§£i3§ _ Oxidation.   Cyanide  in  waste  waters is commonly
destroyed by oxidation with chlorine or  hypochlorite  prior
to  precipitation  of  the  metals.   The  method is simple,
effective, and economically feasible for most waste  waters,
even  for  small  volume  installations.   A  factor  in how
rapidly cyanide is destroyed, if at all, is how strongly the
cyanide is complexed to  metal  ions  and  how  rapidly  the
complex can be broken.  Therefore, some waste waters present
special  problems,   A comprehensive study of the method was
made by Dodge and Zabban.  The results  have  been  used  to
work   out  the  practical  processes.   The  following  are
proposed reactions for chlorine oxidation.
                                98

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                                                                                      Reuse woter
           Cyanide solutions
             Drag out
Cyanide
 waste
treatment
Water
rinse
Chromic
 acid
process
 Chromic
acid waste
treatment
                                                                                           t<
 Sodium
hypochlorite
Feed
pump
                                                           —CxJ-
Water
rinse
                                                                                                        **
                                                                                                  To pH control
                                                                                                    clarif ier
                                                                                                  Water reuse pump
                                                                                                  Water slow down
                                                                                                  to sewer
Cyanide
waste
treatment reservoir



5



?



5
<















7>


Chromium waste
treatment reservoir
5
r^

                                                Feed
                                                pump
                                               Sodium carbonate
                                               Sodium hydro-
                                                      sulfite
                                                                                               To sludge bed
                                   FIGURE  4  INTEGRATED TREATMENT SYSTEM

-------
                                                         •- Water from first
                                                           rinse tank
Air-*-
     ^.;;;M        ^ ^   ^;iUn tanks) v:^ ^           ^0^

     ^VvH^-'$:\^
     •^•.:^.-.**:''.--:-:\-'.t                                            ::':,:
      " ' • •  ; • t: •_•'-''•'••'.: v •  ' -  • .VT                ni»»iiy ^r   ~" 'T—^» TA TI tar ' '. ''
                                                                     .''Measurement
^V-'r-y-y^
^•V;^.-:'^:;"-^:'^5;-^
                                                            To sewer
 FIGURE  D  BATCH TREATMENT  OF CYANIDE RINSE WATERS BY THE  KASTONE PROCESS
                                       100

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    (1)   NaCn + C12 = CNC1 + NaCl

    (2)   CNC1 * 2NaOH = NaCNO + NaCl * H20

    (3)   2NaCNO + 3C12 + 4NaOH = N2 + 2CO2 + 6NaCl + 2H2O.

Reaction (2)  goes rapidly at pH 11.5, under which conditions
build up of the toxic gas CNCl by Reaction (1)   is  avoided.
Treatment  of dilute rather than concentrated solutions also
minimizes its formulation.  Oxidation to cyanate  (NaCNO)  is
completed  in  5  minutes  or  less.  Reaction (3) goes more
slowly, requiring an hour in the preferred pH range  of  7.5
to  9.0,  and  a  longer  time  at  higher  pH.   After  the
conversion to nitrogen and carbon dioxide,  excess  chlorine
is destroyed with sulfite or thiosulfate.

Sodium  hypochlorite  may  be  used  in  place  of chlorine.
Recent technical innovations in electrochemical hypochlorite
generators  for  on-site  use  raise  the   possibility   of
controlling  the  addition  of  hypochlorite  to the cyanide
solution by controlling the current to  the  electrochemical
generator, using sodium chloride as the feed material.

Concentrated solutions, such as contaminated or spent baths,
cyanide  dips,  stripping solutions, and highly concentrated
rinses, are normally fed  at  a  slow  rate  into  a  dilute
cyanide   stream   and   treated  with  chlorine.   However,
concentrated solutions may also be destroyed by electrolysis
with conventional equipment available in the plating shop.39
In  normal  industrial  practice  the  process  is  operated
batchwise,  whereas  the  optimum  system, from an operating
standpoint, would be a cascaded one  in  which  successively
larger  tanks  are  operated  at  successively lower current
densities.  This is the more efficient system.  In  addition
to the oxidation of cyanide at the anode, valuable metal can
be  recovered  at  the  cathode.   The  process becomes very
inefficient when the cyanide concentration reaches  10  ppm,
but  at  this point the solution can be fed into the process
stream for chemical destruction  of  cyanide  to  bring  the
concentration   to  the  desired  level.   The  addition  of
chloride ions to the  concentrated  solutions,  followed  by
electrolysis, produces chlorine or hypochlorite in solution,
which can then destroy the cyanide to the same low levels as
obtained  by  direct  chlorination.  With the provision that
chlorine or hypochlorite be formed at a rate  equal  to  the
concentration  of  cyanide  passing  through the system, the
process can be operated continuously:

  2NaCN * 2NaOCl = 2NaCNO * 2NaCl
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  2NaCNO + 3NaOCl + H2O = 2CO2 + N2. + 2NaOH + 3NaCl

  2NaCN + 5 NaOCl + H2O  2CO.2 + N2 + 2NaOH + 5NaCl.

One proprietary process (A), based on the above  principles,
produces  1  kg  of  active chlorine per 5.5 Kwh.  Equipment
needs are the same with the exception that the tanks must be
lined, and graphite or platinized anodes must be used.

Polysulfide-cyanide strip solutions  containing  copper  and
nickel  do  not decompose as readily and as completely as do
plating solutions.  Although  the  cyanide  content  can  be
reduced  from  75,000  to  1000  mg/1  during  two  weeks of
electrolysis  anode   scaling   prevents   further   cyanide
decomposition  unless  anodes  are  replaced  or  freed from
scale.  Minimum cyanide concentration attainable is about 10
mg/1 after which the solution can be treated chemically.

The electrolysis of dilute cyanide solutions can be improved
by increasing the electrode area.  Area can be increased  by
filling  the space between flat electrodes with carbonaceous
particles.  The carbon particles accelerate the  destruction
process  1000  times, but flow rate through the unit must be
carefully adjusted, if used on a continuous basis to achieve
complete destruction (Plant 30-1).

Although cyanide can be destroyed by  oxygen  or  air  under
suitable  conditions, cyanide concentrations in the effluent
are reported to be 1.3  to  2.2  mg/1,  which  is  high  for
discharge  to sewers or streams.  A catalytic oxidation unit
using copper cyanide as a catalyst and activated  carbon  as
the  reactive  surface  has  been  described  for  oxidizing
cyanide with air or oxygen, and at least two units were  put
in  operation.   Catalytic  oxidation  units  must be custom
designed for each installation for maximum effectiveness.

Ozone  will  oxidize  cyanide  to  below  detectable  limits
independent  of the starting concentration or of the complex
form of the cyanide.  Decomposition  can  be  achieved  with
cyanides  such  as  those  of  nickel  and iron that are not
readily oxidized by chlorine.  Systems that will oxidize the
cyanides that are usually treated,  i.e.,  copper  and  zinc
compounds  have  been  installed  in  production  units  and
demonstrated.  Development work is continuing to enhance the
efficiency and reliability of modern ozone generators and to
decompose  the  more  stable  cyanides  with  the  help   of
ultraviolet radiation and heat.

A   method   employing  thermal  decomposition  for  cyanide
destruction has been recently announced.  Cyanide  solutions
                              102

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are  heated  to  160  to  200  C  under pressure for 5 to 10
minutes.   Ammonia  and  formate  salts  are   formed.    No
information  is  available at this time on the final cyanide
concentration.

Another  proprietary  process  (B),  destroys  cyanides   of
sodium,  potassium,  zinc, and cadmium and also precipitates
zinc and cadmium.  The process is discussed  later  in  this
section.

Precipitation  of  cyanide  as ferrocyanide is restricted to
concentrated  wastes.   Ferrocyanide  is  less  toxic   than
cyanide,  but  is  converted  back  to  cyanide in sunlight.
Treatment is accomplished by adding an amount in  excess  of
stoichiometry  (2.3  kg  of FeSO4 per kg of cyanide).  Large
amounts of sludge are produced which add  to  the  pollution
load.   Complex  cyanides  do not break down readily and the
reaction stops when a concentration of 10 mg/1 of cyanide is
reached.  No benefits can be foreseen in terms  of  reducing
waste volume and concentration.

Cyanide  is  also  destroyed  by reaction with polysulfides.
Reasonable reaction rates are obtained only if the  solution
is  boiled.   Since the reaction does not destroy all of the
cyanide further treatment is necessary.

For a small electroplating facility, it is conceivable  that
an  electrodialysis  system  for  the destruction of cyanide
could be installed.  Experimental work has been performed on
copper cyanide plating baths and is  applicable  to  cyanide
baths of zinc, cadmium, silver and gold.

Reduction   of  Hexayalent  Chromium.   Hexavalent  chromium
 (Cr+*) is usually reduced to trivalent chromium at a pH of 2
to 3 with sulfur  dioxide   (SO2),  sodium  bisulfite,  other
sulfite-containing   compounds,  or  ferrous  sulfate.   The
reduction makes possible the  removal  of  chromium  as  the
trivalent   hydroxide   which  precipitates  under  alkaline
conditions.  Typical reactions  for  SO2  reduction  are  as
follows:

S02 + H20 =H2S03

2H2CrOfi + 3H2S03 =Cr2 (SOU) 3 «• 5H2O.

Representative   reactions   for   reduction  of  hexavalent
chromium  under  acid  conditions  using  sulfite  chemicals
instead of SO2 are shown below:

      (a)  Using sodium metabisulfite with sulfuric acid:
                                103

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          4H2CrOj» + 3Na2S205 + 3H2SO4 = 3Na2SO4 + 2Cr2(SO4)3

                  + 7H2O

     (b)   Using sodium bisulfite with sulfuric acid:

          4H2CrOU + 6NaHS03 + 3H2SO4 = 3Na2S04 + 2Cr 2 (SOU) 3

                  + 10H20

     (c)   Using sodium sulfite with sulfuric acid:

          2H2CrO4 + 3Na2S03 + 3H2SO4 = 3Na2SO4 * Cr2(SO4)3

                  + 5H20.

Reduction  using  sulfur  dioxide  is  the  most widely used
method, especially with larger installations.   The  overall
reduction  is  readily  controlled  by  automatic pH and ORP
(Oxidation-Reduction Potential)  instruments.  Treatment  can
be carried out on either a continuous or batch basis.

Hexavalent   chromium  can  also  be  reduced  to  trivalent
chromium in an  alkaline  environment  using  sodium  hydro-
sulfite as follows:

2H2Cr04 + 3Na2S2O4 + 6NaOH ~ 6Na2SO3 + 2Cr(OH)3 + 2H2O.

As  indicated  in  the  above equation, the chromium is both
reduced  and  precipitated  in  this   one-step   operation.
Results  similar  to those obtained with sodium hydrosulfite
can be achieved using hydrasiine under alkaline conditions.

                  Na2C03

 UH2CrO4 + 3N2HU    =     4Cr(OH)3 + 3N2 + 4H2O.

Sodium hydrosulfite or hydrazine are frequently employed  in
the  precipitation  step  of the integrated system to insure
the complete reduction of any hexavalent chromium that might
have  been  brought  over  from  the  prior  reduction  step
employing sulfur dioxide or sodium bisulfite.  Where ferrous
sulfate  is  readily  available  (e.g.,  from steel pickling
operations), it can be  used  for  reduction  of  hexavalent
chromium; the reaction is as follows:

2CrO3 + 6FeSO4.7H2O «• 6H2SO4 = 3Fe2(SO4)3 + Cr2 (504)3

         + 48H2O.
                                104

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Cr+*  may  be  reduced  at  a  pH  as  high  as  8.5  with a
proprietary compound.  It  is  not  necessary  to  segregate
chromate-containing   waste   waters  from  the  acid-alkali
stream, and the use of acid to lower  pH  is  eliminated  in
this   case.   Precipitation  of  chromic  hydroxide  occurs
simultaneously in this case with the reduction.

Cr+* ions may be reduced electrochemically.  A concentration
of 100 mg/1 was reduced to less than 1  mg/1  with  a  power
consumption   of   1.2  kwh/1000  liters.   The  carbon  bed
electrolytic process previously described for cyanide2*  may
also  be  used  for  chromate reduction in acid solution and
Plant 30-1 has achieved a Cr+*  concentration  of  .01  mg/1
using  this  method.   Electrolysis  may  also  be  used  to
regenerate a reducing agent.  A process51 has been described
involving the reduction of Fe+3  to  Fe+2  electrochemically
and  the  reduction  of  Cr+* by Fe+2.  The method should be
capable of achieving low Cr+6 levels.

The simultaneous reduction of Cr+* and oxidative destruction
of cyanide finds  limited  application  in  waste  treatment
practice.   The  reaction requires mixing of Cr+* and CN~ in
ratios  between  2  and  3  using  Cu+2  as  a  catalyst  in
concentrations  of  50 to 100 mg/1.  The catalyst introduces
additional pollutant into the waste stream.  Reaction  rates
are generally slow, requiring from 6 to 24 hours for cyanide
concentrations  ranging from 2,000 to less than 50 mg/1 at a
solution pH of 5.  The slowness of the reaction and the high
initial concentrations of reactants required make the method
unsuitable for treating rinse waters.  Its use is limited to
batch treatment of concentrated solutions.  No benefits  are
obtained  in  terms of water volume and pollution reduction.
Destruction is not as  complete  as  obtained  by  the  more
common chemical methods.

Unit Operations

Precipitation.   The  effluent levels of metal attainable by
chemical treatment depend upon  the  insolubility  of  metal
hydrolysis  products  in  the  treated  water and upon their
settling and  filtering  characteristics  which  affect  the
degree  to which they can be separated.  The solubilities of
the hydrolysis products are dependent upon  many  conditions
during  precipitations such as pH, presence of other cations
and anions, time allowed before separating out  the  solids,
the precipitation agent used, the degree of agitation, etc.

Schlegel  and Hartinger have studied precipitation reactions
extensively and have been able to obtain low  concentrations
of metal ions in solution within 2 hours.
                             105

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When  metal ions are precipitated separately the pH may have
to be adjusted differently for each ion.   This  immediately
raises the question of whether the metals can be efficiently
precipitated  tocrether  at a common pH.   This is possible as
shown in Table 2 6-

It is apparent that it is difficult to predict in detail the
conditions that will give the best precipitation results  in
a  practical situation.  However, just as several parameters
can be adjusted in the laboratory to obtain optimum results,
suitable conditions may be found in the field.  Flocculating
agents, added to aid in settling  the  precipitate,  play  a
significant  role  in  reducing  concentration  of suspended
solids.

When  solubilizing  complexing  agents  are   present,   the
equilibrium  constant  of  the complexing reaction has to be
taken into account  in  determining  theoretical  solubility
with  the  result  that  the  solubility  of  the  metal  is
generally increased.  Cyanide ions  must  be  destroyed  not
only  because  they  are toxic but also because they prevent
effective precipitation of copper and  zinc  as  hydroxides.
If  cyanide  is  replaced  in  a  plating bath by a nontoxic
complexing agent such  as  EDTA  (ethylenediaminetetraacetic
acid),   the   new   complexing  agent  could  have  serious
consequences  as  far  as  the  removal  of  metal  ions  by
precipitation.  Ammonium ion, present in many electroplating
baths,  will  complex copper, zinc, and other metal ions and
interfere with their precipitation as hydroxides.

Theory and experimental  results  confirm  that  it  is  not
possible  to  achieve  complete  removal  of metal ions from
waste  water  by  precipitation  as   hydroxides   even   if
separation of precipitate were 100 percent effective.  Thus,
a  finite  concentration  of  pollutant  will  remain in the
effluent.  The best indication of what can  be  achieved  in
reducing   metal  concentration  is  the  results  of  daily
operation  in  exemplary  plants  rather  than   theory   or
laboratory  experiments..   Clarification  efficiency  is  an
important factor in determining the total metal  content  of
the  effluent.   It  is  safe  to say that the soluble metal
content will be no greater than the total  content  achieved
in practice and may be less..

Solids _Separation.   The  first step in separating the pre-
cipitated metals is settling, which is very  slow  for  gel-
like  zinc  hydroxide, but is accelerated by coprecipitation
with the hydroxides of copper and chromium.  Coagulation can
also be aided by adding metal ions such as ferric iron which
forms  ferric  hydroxide  and  absorbs  some  of  the  other
                               106

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TABLE 26   COMPARISON OF SOLUBLE POLLUTANT
           PARAMETERS AFTER PRECIPITATION
           BY IRON SULFIDE OR BY HYDROLYSIS
                     Pollutant residues from--
Waste
compo-
sition
in ppm
Unknown

Cu, 100
Ni, 7.7
NH3, 475
NH3, 475

Cr(VI), 4.8
Zn, 3.5
Sulfide
precipi-
tation
in ppm
Cu, 0.1
Zn, negligible
Cu, 1.8


Cu, 0.4
Ni, 2.0
Cr(VI), negligible
Zn, 0.03
Hydroxide
precipi-
tation
in ppm
0.8
2.0
95.8
5.9

1.0
2.0
0.05
2.0
                     107

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hydroxide, forming a floe thcit will settle.   Ferric iron has
been  used  for  this  purpose  in sewage treatment for many
years  as  has  aluminum  sulfate.    Ferric   chloride   is
frequently added to the clarifier of chemical wastetreatment
plants  in plating installations.  Flocculation and settling
are further improved by use of polyelectrolytes,  which  are
high   molecular   weight  polymers.   Due  to  their  ionic
character  they  are  capable  of  swelling   in  water   and
adsorbing  the  metal hydroxide which they carry down during
settling.

Settling is accomplished in the batch process in a  stagnant
tank, and after a time the sludge may be emptied through the
bottom  and the clear effluent drawn off through the side or
top.  The continuous system uses a baffled  tank  such  that
the  stream  flows  first  to  the  bottom  but rises with a
decreasing vertical velocity until the floe  can settle in  a
practically stagnant fluid.

Although  the  design  of  the  clarifiers has been improved
through many years of experience, no settling techniques  or
clarifier  will  completely  remove solids from the effluent
which contains typically 5 to 20 mg/1 of  suspended  solids.
This floe contains some metal.

Sludge  Disposal.   Clarifier underflow or "sludge" contains
typically 1 to 2 percent solids  and  can  be  pumped  to  a
lagoon.

Metal  ions  in  the  liquid  associated with the sludge can
percolate through porous soil and become a potential  source
of  groundwater  contamination.   Impervious lagoons require
evaporation into the atmosphere. However, in many  parts  of
the  U.S., the average annual rainfall equals or exceeds the
atmospheric evaporation.  Additionally, heavy rainfalls  can
fill  and  overflow lagoons.  Metal ions may be leached from
metal hydroxides and the surface run-off to adjacent streams
or lakes may be in sufficient quantity to be detrimental.

A case in point is contamination of groundwater  by  plating
wastes  held in lagoons in Nassau County, New York.  Plating
wastes have seeped down from the lagoons into  the  aquifier
intermittently  since  1941.  This seepage has resulted in a
plume of contaminated water some  4,300  feet  long,  up  to
1,000  ft  wide,  and  as  much  as  70 feet deep, extending
downgrade to the headwater of Massapequa Creek.   Originally
the  plating waste water was untreated and the concentration
of hexavalent chromium in the groundwater was about 40 mg/1.
Since the start of chromium treatment,  concentrations  have
decreased  to  less  than  5  mg/1  in  most  of  the plume.
                              108

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Treatment of the plating waste effluent results in discharge
of sludge to the lagoons, and the sludge forms a  lining  on
the  bottoms  and  sides  which  retards  infiltration.   At
another location core-drilled samples were obtained from the
shale structure underlying the  bed  used  for  disposal  of
sludge resulting from chemical treatment.  The disposal side
had been in use for several years.  Metal concentrations two
feet  into  the  shale structure, were of the order of 50 to
100 ppm.

Lagooning can be avoided  by  dewatering  the  sludge  to  a
semidry or dry condition.  Several devices are available for
dewatering  sludge.   Rotary vacuum filters will concentrate
sludge containing 4 to 8 percent solids to 20 to 25  percent
solids.   Since  the  effluent  concentration  of  solids is
generally less than 4 percent  a  thickener  tank  is  often
employed between the clarifier and the filter.  The filtrate
often   contains   excessive   suspended   solids   and   is
recirculated to the clarifier.

Centrifuges will also thicken sludges to the above range  of
consistency  and  have  the  advantage  of  using less floor
space.  The effluent contains excessive suspended solids and
is returned to the clarifier.

Pressure filters may be used.  In contrast to rotary filters
and centrifuges, pressure filters will  produce  a  filtrate
with  less than 3 mg/1 of suspended solids so that return to
the clarifier is  not  needed.   The  filter  cake  contains
approximately 20 to 25 percent solids.  Pressure filters are
usually  designed  for  a  filtration  rate  of 2.04 to 2.44
liters/min/sq m  (0.05  to  0.06  gpm/sq  ft)  of  clarifier
sludge.

Solids contents from 25 to 35 percent in filter cakes can be
achieved  with semicontinuous tank filters rated at 10.19 to
13.44 1/min/sq m (0.25 to 0.33 gpm/sq ft) surface.  A solids
content of less than 3 mg/1 is normally accepted for  direct
effluent discharge.  The units require minimum floor space.

Plate  and  frame  presses  produce filter cakes of 40 to 50
percent dry solids and a filtrate  with  less  than  5  mg/1
total suspended solids.  Because automation of these presses
is  difficult,  labor  costs tend to be high.  The operating
costs are partially offset by low capital equipment costs.

Automated tank type pressure filters are  just  now  finding
application.   The  solids  content of the cake can reach as
high as 60 percent while the filtrate may have up to 5  mg/1
of   total   suspended   solids.   The  filtration  rate  is
                               109

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approximately  2.04  1/min/sq  m  (0.05  gpm/sq  ft)   filter
surface  area.   Pressure filters containing from 300 to 500
mg/1  suspended  solids  at   design   of   U.88   to   6.52
liters/min/sq  m (0.12 to 0.16 gpm/sq ft) and still maintain
a low solids content in the filtrate.

Filter  cakes  can  easily  be  collected  in  solid   waste
containers  and  hauled  away  to  landfills.   There may be
situations, however, where the  metal  in  the  filter  cake
could  be  redissolved  if  it came into contact with acidic
water.  Careful consideration should be given to where  such
a material is dumped.

A proprietary process is available for solidifying sludge by
addition of chemical fixing agents.  Relative to filtration,
the  amount  of dried sludge to be hauled away is increased.
The fixing process appears to insolublize the metal ions  so
that in leaching tests only a fraction of a part per million
is found in solution.  A fill is produced that is similar to
dried clay.

The  possibility  of  recovering  metal  values from sludges
containing copper, nickel,  chromium,  and  zinc  have  been
considered  but such a system appears to be uneconomic under
present circumstances. It may be profitable to recover metal
values if 900 to 2300 kg  (2,000 to 5,000  pounds)  of  dried
sludge  solids  can  be  processed per day with a thoroughly
developed process.  To attain  this  capacity  would  almost
certainly  require that sludge from a large number of plants
be brought to a central processing  station.   The  recovery
would   be   simpler   if  the  metallic  precipitates  were
segregated,  but   segregation   would   require   extensive
modification,  investment,  and  increased operating expense
for precipitation and clarification.  Laboratory experiments
showed that zinc could be leached from sludge  with  caustic
after  which  copper,  nickel, and chromium were effectively
dissolved with mineral acids.  Ammonium  carbonate  dissolved
copper  and nickel but not trivalent chromium, thus giving  a
method of separation.   Electrowinning   of  the  nickel  and
copper  appeared to be a feeisible method of recovering these
metals.

Precipitation of Metal Hydroxides

Applicability.  Chemical treatment was used by   every  plant
contacted  during  the  effluent  guidelines  study with the
exception of  those that are  allowed  to discharge  plating
waste effluents into  sewers or streams without treatment.
                              110

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             _            TreatingjTechnigues.           The
effectiveness of chemical treatment  techniques  depends  on
the nature of the pollutant, the nature and concentration of
interfering  ions,  the  procedure of adding the appropriate
amount of chemicals (or adjusting pH), the reaction time and
temperature and the achievement of effective  separation  of
precipitated  solids.   Effective removal of metal pollutants
is inhibited  by  some  types  of  chelating  ions  such  as
tartrate or ethylene diamine tetracetate ions.

The  concentrations  of metals and cyanide achievable by the
chemical techniques employed for treating waste from copper,
nickel,  chromium,  and   zinc   electroplating   and   zinc
chromating   processes   are   summarized   in   Table   25.
Concentrations lower than those listed as maximum  in  Table
57  were  reported by companies using all three (continuous,
batch, and integrated)  treating systems.

Higher-than-normal  concentrations  of  metals,  when   they
occur,  are usually caused by:   (1) inaccurate pH adjustment
(sometimes  due  to  faulty  instrument  calibration);   (2)
insufficient  reaction time;  (3) excessive concentrations of
chelating agents that complex the  metal  ions  and  prevent
their  reaction  with  hydroxyl  ions  to form the insoluble
metal hydroxides; or (4) lack  of  suitable  coprecipitating
agents.  The causes for higher-than-normal concentrations of
cyanide  are  similar,  but another important factor must be
added to the list of potential causes for incomplete cyanide
destruction.  In this case, sodium  hydroxide  and  chlorine
must  be  added continuously during the reaction to maintain
the optimum pH and provide sufficient  reagent  to  complete
the  reaction,  which is normally monitored by an Oxidation-
Reduction-Potential     (ORP)    recorder-controller.     The
maintenance  of  this  system is a critical factor affecting
the effectiveness of chemical oxidation.

Practical_Operating_Sxstems.  In Plant 33-2 the discharge of
cyanide is eliminated by electrochemical decomposition in  a
tank held at sufficiently high temperatures to evaporate the
waste  water  as rapidly as it is introduced.  Therefore, no
liquid stream leaves the tank.  Fluorides  and  fluoroborate
containing   waste  waters  in  Plant  31-16  are  collected
separately and treated with lime.

Plant 36-8 disposes of sludge in a pit  lined  with  special
concrete  blocks  that filter out solids and allow liquid to
permeate into the surroundings.   Relatively  few  finishing
plants  have  installed  filters,  although  the  problem of
disposing of unfiltered sludge in many cases should  provide
an impetus for the use of one or more filters in the future.
                              Ill

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Plants   12-8   and   31-16  use  large  rotary  filters  to
concentrate sludge from a clarifier.  Plant 33-30 is able to
filter the solution from the neutralizer directly, without a
preceding clarification step.  A  settling  tank  centrifuge
combination   is   in   use  in  over  200  waste  treatment
installations, including those in electroplating plants.   A
proprietary  system  for  solidifying  sludge  is  in use at
several plants.

Demonstration.Status.  The US Bureau of Mines has done  some
development  on  a  process  in  which  the  acid wastes and
alkaline cyanide wastes neutralize  each  other.   The  acid
wastes  are  slowly added to the alkaline wastes in a closed
reactor to form easily filtered metal cyanide  precipitates.
The  precipitates  are  heated  in  air to form stable metal
oxides.

Suspended^Solids.  The  suspended  solids  discharged  after
treatment  and clarification sometimes contribute more metal
than  the  dissolved  metal.   The  concentration  of  total
suspended  solids  in the end-of-pipe discharge from typical
chemical treatment  operations  sampled  during  this  study
ranged  from  20  to 24 mg/1.  Lower values are reported for
some facilities.  Maintaining conditions so as not to exceed
these amounts requires (1)  a properly designed  settling  or
clarifying  facility,  (2)   effective  use  of  flocculating
agents, (3)  proper control of the rate of removal of settled
solids, (4)  sufficient retention time for settling, and  (5)
rate  of  overflow  of  clarified  effluent.     of  course,
minimum retention time depends  on  the  facility  size  and
design  and  the rate of solution flow through the facility.
In practice, this time ranges from about 2 to  8  hours  for
plants  that are able to reduce suspended solids to about 25
mg/1 or less.

Precipitation of Metal Sulfides

Applicability.  The sulfides of metals are much less soluble
than  their  corresponding  hydroxides.    However,   direct
precipitation  of metal ions with hydrogen sulfide or sodium
sulfide involves the problem of excess sulfide ion which can
then become an additional pollutant  parameter.   A  sulfide
precipitation system has recently been developed that avoids
the  possibility  of  excess  sulfide  ion  being present in
treated effluent.  Iron sulfide, which  itself  has  a  very
small  solubility,  is  used  as  the reagent to precipitate
copper, zinc, and nickel sulfides of even lower  solubility.
Experimental  results  are shown in Table 26 indicating that
low   concentrations   can   be   achieved   with    sulfide
precipitation even when metals are complexed with ammonia.
                                112

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The  disposal  of  sulfide  solid  wastes  is  a serious and
unsolved problem.  Unlike the metal oxides, metal  sulfides,
in  the presence of air, decompose to sulfates and the metal
ions can thereby be solublized.  This  commonly  happens  to
ferrous  sulfide  as  a result of coal mining operations and
contamination of streams with acid and  iron  is  a  result.
However,  there  is  insufficient  information  available to
determine whether any significant oxidation will occur  with
mixed   metal   sulfide  sludges  disposed  of  properly  on
landsites.   The lower solubility of metal  sulfides  should
reduce   the   amount   leached   directly  into  rainwater.
Therefore, if significant oxidation is found to occur, means
will have to be found to contain the sulfide precipitates or
insolublize them by some system such as the Chemfix Process.
Practical Operating. SYgt^s.  Plant 9-2 is  segregating  its
plating streams and precipitating cadmium as the sulfide.

Demonstration  Status.  The process described is still being
developed, and it is anticipated that a demonstration  plant
will be built and operating in the near future.

Combined Metal Precipitation and Cyanide
Destruction-Proprietary Process B

Applicability.   This  process  is  applicable  to  zinc and
cadmium  cyanide  solutions.    The   metal   hydroxide   is
precipitated   and  cyanide  is  decomposed.   Applicability
depends  upon  deciding  whether  the  products  of  cyanide
decomposition  are  suitable  for  discharge  or  not.   The
effluent is considered suitable for discharge to  sewers  in
some states.  A modified process may be applicable to copper
cyanide.

Process _ Principles __ and __ Equipment •   Cyanide  in  zinc and
cadmium plating baths is destroyed by a mixture of  formalin
and hydrogen according to the formula:

3CN- + 2H202 + HCOH + 2H2O = CNO~ + OH~ + NH3

    + H2C (OH) CONH2)  (glycolic acid amide) .

The  metal  hydroxide  is  also  precipitated.  The hydrogen
peroxide is contained in the reagent   (41%)  which  contains
stabilizers  and additives to promote the reactions and help
in settling the metal hydroxide  precipitate.   The  process
may  be  carried  out on a batch or continuous basis, and is
particularly convenient for the small  shop.   However,  the
glycolic  acid  generated is not a desirable constituent for
                                113

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discharge to streams and the use of the  process  should  be
restricted to plants discharging to sewers.

Figure  1  shows  the  apparatus for batch treatment.  To be
economical the rinse water should contain at least  55  mg/1
of  cyanide, and sufficient counter-flow rinses are normally
installed to assure a sufficient cyanide concentration.  The
typical treated effluent contains 0.1 mg/1 of cyanide and  1
to  2  mg/1  of  zinc.   Table  27  shows an analysis of the
products for decomposing 79<* ppm of cyanide.

Practical Ope rating Systems^   This    process    is    well
established  as  a practical means for pollution control and
is being used in approximately 30 installations.

Chemical Treatment of Effluents From Specific
Process operations

Constituents

Iron.  Iron baths have relatively  simple  compositions  and
neutralization  of  waste water constituents will reduce the
soluble  iron  concentration  well  below  1  mg/1.   Ferric
chloride  is  a common constituent in such baths and is used
as a flocculating agent in clarification systems for Phase I
metals  following  neutralization,  to  give   an   effluent
suitable  for discharge.  The waste waters  (dilute acid) and
the concentrated  plating  baths  (concentrated  but  weakly
acidic)  enter  the  waste  treatment system via the "dilute
acid-strong acid" streams of Figure 2.

Cadmium.  After oxidation of cyanide or in noncyanide  waste
water,  cadmium  can  be  precipitated  as  the hydroxide by
adjustment of pH.   The  waste  water  and  strong  solution
discharge  streams  are  shown as "weak cyanide" and "strong
cyanide" in Figure 2.  Alkalinity has a  significant  effect
on solubility of cadmium.  The theoretical solubility values
according to Ponrbaix are approximately

                                   Solubility
           pH                         mg/1

            8                      3000
            9                        30
           10                         0.03
           11                         0.003  (minimum)

Therefore,  soluble  cadmium  might  not be reduced to a low
level by coprecipitation with Cu, Ni, Cr, Zn at pH 8  to  9.
Should  a  pH  of  11 be used, there is danger that the zinc
                                 114

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  TABLE 27   DECOMPOSITION PRODUCTS OF CYANIDE IN
             RINSE WATER(1) FROM A CYANIDE ZINC
             ELECTROPLATING OPERATION AFTER TREATMENT
             WITH "KASTONE"(2) PEROXYGEN COMPOUND
                                 Amount Formed
   Products Formed       Actual     Cyanide Equivalent
    by Treatment          ppm         ppm     percent


Cyanate                   351         265        33

Ammonia  (free
  Dissolved                57         164        21
  Volatilized(3)           32          91        11

Combined Ammonia  .
  Calc'd as NH3            95
  Calc'd as glycolic                  274        35
    acid amide            419
                                      794       100
(1)  Analysis of water before treatment:
       Cyanide*    794 ppm
       Cyanate*    336 ppm
       Ammonia *    41 ppm

   ¥Cyanide calculated as NaCN, cyanate as NaOCN, and
     ammonia as NH^.

(2)  Du Pont trademark.

(3)  Not determined;  estimated by difference.
                        115

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concentration  in   the   effluent   will   be   too   high.
Consideration  of  the  above theoretical data suggests that
cadmium  might  not  be  reduced  to  a   low   level   when
coprecipitated  with  Cu,  Ni,  Cr,  Zn  at  pH 8 to 9.  The
insolubility   of   cadmium    carbonate    suggests    that
precipitations  with  soda ash may reduce soluble cadmium to
very low levels in effluent.

Separation of Streams

Prior to chemical treatment,  waste  waters  from  different
operations  in  a  electroplating process may be combined in
some cases and kept separate in other cases.  The nature  of
the  waste  waters and the pollutants present will determine
where segregation is  desirable  and  where  combination  is
practical.   Some  pollutants  cannot be properly removed in
the presence of others, while some are better  removed  when
combined  with  others.   Combination  of  some streams will
result in a reaction to form additional pollutants and  ones
that can be of immediate danger to personnel involved in the
electroplating operations, e.g., a cyanide containing stream
combined with an acid stream may cause evolution  of gaseous
hydrogen  cyanide.   In  general,  waste  waters  containing
cyanide are segregated and treated separately, waste  waters
containing  hexavalent  chromium  are segregated and treated
separately.  After treatment the cyanide, chrome, and  metal
ion   streams   are   combined   for  further  treatment  to
precipitate  metal  hydroxides  which   are   settled   out,
sometimes  filtered, and disposed of on land.  The treatment
facilities may  be  engineered  for  batch,  continuous,  or
integrated  operations.   However, the treatment methods for
several  pollutants  can  deviate  considerably  from   this
general plan.  The design of a suitable procedure and system
to treat a specific pollutant mix requires considerable care
and experience.

Since  many  combined waste waters contain some carbonate it
is very possible that cadmium carbonate rather than  cadmium
hydroxide  is precipitated when waste waters are neutralized
with caustic  or  lime.   Some  reported  values  that  seem
unrealistically  low  for  hydroxide  precipitation  may  be
achieved  by  this  mechanism.    Cadmium  sulfide  is   very
insoluble   (solubility  product  K  =  10~2«),  so  that  a
precipitation system  based  upon  sulfides,  combined  with
efficient   removal   of   dissolved   solids,  may  provide
acceptable effluent.  A schematic of the treatment scheme is
shown in Figure 6.  In  this  figure,  the  cadmium  sulfide
sludge  is  recovered.  If segregated treatment of a cadmium
stream is required, the best way of holding the  sludge  may
                              116

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                                   Water
I	
 Adjust
  PH
 Sulfide
Precipitate
Liquid effluent
                                                          Metal
                                                         Recovery
      FIGURE  6   SCHEMATIC FOR SULFIDE PRECIPITATION
                  OF CADMIUM IN WASTEWATERS
                               117

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be  to  ship it to a metal recovery unit, or convert it to a
form suitable for return to the plating bath.

Alternative to recovering sulfide precipitate, an evaporator
can be installed to recover plating bath and reusable water.
A small bleed-off may be required to  decrease  contaminants
in the plating bath, as shown in Figure 7.

When  cadmium plating is done in noncyanide baths, the waste
treatment is the same except that the cyanide oxidation step
is omitted.  Fluoborate containing wastes come from a  small
amount  of  cadmium  plating.   Fluoborate  is  covered in a
separate section.

Lead.   There  is  a  possibility  that  an  adequately  low
concentration  of  dissolved  lead  cannot be achieved by pH
adjustment.  Pourbaix gives the  following  solubility  data
for lead hydroxides.

                                  Solubility
          22
           8                       500
           9                         6
           9.U                       3 (minimum)

The  chloride  and  sulfate  are  too  soluble  to achieve a
sufficiently   low   lead   concentration,    but    sulfide
precipitation  should  reduce  the concentration adequately.
Lead carbonates and basic carbonates have  low  solubilities
and   therefore   carbonate   present  incidentally  in  the
neutralization process or deliberately added may reduce lead
to low levels in effluent.  The problem of suspended  solids
remains.  Sludge would most appropriately be sent to a metal
recovery  unit or be converted to a form suitable for return
to the plating bath.  Waste treatment operations are similar
to those shown for cadmium in Figures 6 and 7, omitting  the
cyanide oxidation.  Lead plating wastes contain fluoroborate
which is covered in a subsequent section.

Tin.   The tin concentration can be reduced to low levels by
neutralization between pH 8 amd 9 whether the tin is present
in the divalent form from acid  baths  or  the  quadrivalent
form  from alkaline baths.  Therefore, chemical treatment is
adequate for this constituent.  In  principle,  the  sulfide
precipitation  method, as discussed for cadmium and lead, is
applicable to tin.

Precious, Metals.  Silver, gold, and platinum metals in rinse
waters generally are recovered by some method  such  as  ion
                             118

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                                     Water
     1	
                   Dry Sludge
                   to Recovery
FIGURE  7  SCHEMATIC OF CADMIUM WASTEWATER
           TREATMENT WITH MINIMUM SOLID
           DISPOSAL
                      119

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exchange,  evaporation,  or electrodeposition.  Concentrates
as well as unusable baths are returned to a salvage  company
for  recovery  of metal values by methods involving chemical
treatment.

Processes
             Since several of the plating baths  (those  for
lead,  tin,  and their alloys) contain the fluoroborate ion,
the applicability of chemical treatment to remove  this  ion
from  liquid  effluent  is  of  interest.  Upon dilution the
fluoroborate hydrolyzes:
                H2O = HF + BF3 + OH~.

The BF3 is very stable.

Thus, the problem is to reduce the concentration  of  HF  in
the  waste  water.   The  fluoride  may be precipitated with
lime,  but  the  concentration  can  be  reduced   only   to
approximately  15  mg/1.   This  suggests  that fluoroborate
plating  baths  be  operated  as  closed-loop  systems  with
recovery  by  evaporation,  and  that  spills  and  leaks be
segregated so that they can be treated separately.  In  this
way,  the fluoride discharged in liquid effluent can be held
to a very small amount.

Wire and.. Strip.  Effluent constituents from copper,  nickel,
chromium,  zinc,  and  tin  plating  of  wire  and strip are
amenable to the same chemical treatment methods as discussed
previously.

Activation_and_Cataly^ing.  Chemical  precipitation  is  the
method   generally  used  for  treating  wastes  from  these
operations for  preparing  plastics  and  nonconductors  for
plating.  Rinse waters contain tin for activating and palla-
dium   from   catalyzing   operations.    Waste  Waters  are
segregated and  treated  separately  by  neutralization  and
precipitation.   The tin is precipitated at pH 8 and removed
by settling or filtration.  The palladium is precipitated at
pH 8 to 9 and recovered by settling or filtration.

                  s.  Effluents from  chromating  operations
          _
are  amenable to chemical treatment to reduce the hexavalent
chromium and precipitate  trivalent  hydroxide  as  done  in
treating waste water from chromium plating.  Phosphates from
phosphating operations can be reduced to the 1 mg/1 level by
addition  of  aluminum ions.  Removal of phosphate can occur
when aluminum  sulfate  is  added  to  the  clarifier  as  a
flocculating  agent.   Heavy  metals, such as iron and zinc,
                             120

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derived from the basis metals and solution formulations, are
removed by neutralization and precipitation.

Water ConservationTIn Process_ContrQls

The volume of effluent is  reduced  if  water  is  conserved
during rinsing operations.  The solubility limit of effluent
constituents is essentially constant, so that a reduction in
the  effluent  volume accomplishes a reduction in the amount
of effluent constituents discharged.  Water conservation can
be accomplished by in-plant process modifications  requiring
little  capital  or  new equipment, materials substitutions,
and good housekeeping practice.  Further water  conservation
is  obtained  by installing counterflow rinse tanks and ion-
exchange, evaporative recovery, or reverse osmosis  systems.
Other  systems  that  may  accomplish water conservation are
freezing, electrodialysis,  electrolytic  stripping,  carbon
adsorption, and liquid-liquid extraction.

Process Modifications

Substitution  of  low-concentration electroplating solutions
for high-concentration baths  has  been  adopted  in  recent
years,  principally  for reducing the cost of chemicals used
for cyanide destruction.  The dilute solutions require  less
water  for rinsing when electroplating parts are transferred
to rinse tanks.  Assuming a 50 percent  reduction  in  total
dissolved solids in the plating solution and two rinse tanks
in   series,   a   30   percent  reduction  in  rinse  water
requirements  is   achieved.    Waste   Water   constituents
requiring  treatment are reduced by the same amount. Adverse
effects  in  terms   of   lower   efficiency   and   reduced
productivity  per  unit  facility  may  be  encountered when
dilution is adopted to conserve rinse water and reduce waste
water constituents requiring treatment, unless other factors
affecting plating  rate  are  modified  to  adjust  for  the
effects  of  dilution.  Thus, dilution should not be adopted
before a complete analysis is made of all pertinent factors.

The advent of effluent limitations is expected to  encourage
research  and  development  on  other  processes  that  will
eliminate or reduce water waste.  A dry process for applying
chromate coatings, which is currently being  developed,  may
prove  useful  for  such  a  purpose, for example.  Chemical
vapor deposition processes partially developed a  few  years
ago may be revived for plating hard chromium.

Material Substitutions
                            121

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Noncyanide  solutions,  which  have been developed for metal
finishing operations in place of cyanide  solutions,  reduce
the  costs  of treatment by eliminating cyanide destruction,
but do not eliminate treatment to precipitate  and  separate
the  metals.   The  chelating  agents  employed in some non-
cyanide  baths  to  keep  the  metal  in  soluble  form  are
precipitated  when rinse water waste is treated with lime to
precipitate the metals, but other agents  such  as  ethylene
diamine  tetraacetic  acid inhibit the precipitation of zinc
and contribute organic matter to the  treated  water  waste.
Thus,  the  applicability  of.  the  noncyanide  solutions as
replacements for cyanide baths must be considered carefully.

Trivalent chromium baths have recently  been  introduced  to
the  electroplating  industry.   They eliminate the need for
sulfur dioxide reduction  of  waste  water  associated  with
chromium  plating.   The  trivalent chromium baths appear to
have other advantages for decorative plating such as  better
throwing  power,  current  efficiency and plating rate.  The
dark color of the deposits is cited  as  a  disadvantage  by
some   purchasers,   however.,   Nevertheless,  this  process
modification may ultimately  prove  to  be  significant  for
reducing  waste  treatment  costs.   No  details  have  been
released  on  the  treatment  required  for  minimizing  the
soluble chromium concentration in treated effluent, however.

Good Housekeeping Practices

Good  housekeeping practices that reduce the waste generated
in electroplating facilities include the following:

      (1)  Maintain racks and rack coatings to prevent
           the transfer of chemicals from one operation
           to another. (Loose rack coatings are
           noteworthy as an example of poor practice.)

      (2)  Avoid overcrowding parts on a rack, which
           inhibits drainage when parts are removed
           from a process solutions.

      (3)  Plug all floor exits to the sewer and con-
           tain spills in segregated curbed areas or
           trenches, which can be drained to direct
           the spills to rinse water effluent with the
           same chemicals.

      (H)  Wash all filters, pumps and other auxiliary
           equipment in curbed areas or trenches,
           which can be drained to direct the wash
           water to a compatible holding tank or
                             122

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           rinse water stream.

      (5)   Install anti-syphon devices on all inlet
           water lines to process tanks.

      (6)   Inspect and maintain heating and cooling coils
           to avoid leaks.

      (7)   Inspect and maintain all piping installed for
           waste water flow, including piping from fume
           scrubbers.

Water Conservation by Reducing Dragout

Dragout.  Dragout is defined as solution  on  the  workpiece
carried beyond the edge of the processing tank.  The dragout
of  concentrated  solution from the processing tank can vary
over a wide range depending on the shape factor of the part.
A value of  16.3  1/1000  sq  m   (0.4  gal/1000  sq  ft)   is
considered  a  minimum  for  vertical  parts  that  are well
drained.  The practical range for parts  of  various  shapes
that  are  well drained is about HO to 400 1/1000 sq m (1 to
10 gal/1000 sq ft) .

2£§32]Jt_Beductign.  Water used for rinsing can be  conserved
by" (if "improving the racking procedure to improve drainage
from surfaces over the process tank, prior  to  transfer  to
the  subsequent rinse tank,  (2) increasing the drainage time
over the process tank,  (3) reducing  the  viscosity  of  the
process   solution   by   diluting   it  or  increasing  its
temperature,  (t) adding  a  wetting  agent  to  the  process
solution  to  reduce  surface  tension,  (5)   installing fog
nozzles above the process tank  to  return  a  part  of  the
solution remaining on work surfaces to the process solution,
and  (6)  installing  a drip-save (reclaim) tank between the
process and rinse stations to collect dragout that is pumped
back to the process solution.  A mixture of air and water is
utilized in one version  of  a  fog  nozzle  claimed  to  be
especially  effective for removing most of the solution from
surfaces  lifted  above  process  tanks.   With  the   above
techniques,  the  water needed for rinsing can be reduced as
much as 50 to 60 percent.

Reduction of dragout with the above methods is  not  without
problems.    By  returning  chemicals to the processing tank,
impurities tend to build  up  in  the  processing  solution.
Therefore,  purification  systems,  such  as  ion  exchange,
batch-chemical treatments, or electrolytic purification  are
required  to  control  impurities.  The purification systems
                              123

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create some effluents which must be treated prior to end-of-
pipe discharge.

Water Conservation During Rinsing

Water conservation procedures that are used after  processed
work  is  transferred  to  a rinse tank include (1)  adding a
wetting agent to the rinse  water,  (2)   installing  air  or
ultrasonic  agitation  and (3)  installing counterflow rinses
whereby water exiting the last tank in the rinsing operation
becomes feed  water  for  the  preceding  rinse.   With  two
counterflow  rinses, water consumption is reduced 96 percent
in comparison with a single rinse, assuming that the dragout
solution mixes  immediately  with  the  rinse  water.   This
assumption  is  incorrect.   While  a  part  of  the dragout
solution mixes rapidly with the rinse water, particularly if
agitation  is used, the remaining film on the work comes off
rather slowly by a diffusion process.  A more typical  value
for  the  water  reduction  might be 85%t corresponding to a
rinsing   efficiency   of   approximately   90%.    Use   of
conductivity  meters  in  the final rinse provides automatic
control of water use according to need.   Rinse water flow is
shut off automatically when  no  work  is  being  processed.
Excessive  use  of  water can also be avoided by use of flow
restrictors in the water feed lines.

Although  multitank,  counterflow  rinsing  imposes  capital
investment  costs  for  tanks,  pumps, and floor space, these
costs are compensated for by a savings in water (and  sewer)
charges.   Further  incentive  is  provided  when regulatory
agencies require pollutional control.   When  end-of-process
chemical  treatment  is  used,   design  of  waste  treatment
facilities  usually  indicates   the  economic  advantage  of
reducing   rinse-water   flow  by  installing  two  or  more
counterflow rinses.

Because waste treatment facilities are usually over designed
to  handle  future  expansion  in  production,  there  is  a
tendency  to  use  the  water flow capacity of the treatment
facility whether or not it is needed for effective  rinsing.
Furthermore,  rinse  water  flows  set by an orifice are not
always turned off when plating  production is shut down.   It
is  probably  more economical to reduce rinse water usage by
use  of  good  rinsing  practice  than  to  increase  water-
treatment   facilities  in  the  event  of  an  increase  in
production.

Rinsing can be carried out beyond the point consistent  with
good practice, even though there is an economic incentive to
save  water.   The result is unnecessary pollution.   Typical
                              124

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          concentration   levels   permitted   in   the   rinses   following
          various  process   tanks,   should   not   be   decreased unless
          definite quality  problems  can be  associated  with   the   dis-
          solved solids  concentrations  listed below  for representative
          rinsing systems:

                                             Max Dissolved  Solids
               	Process	         in Final  Rinse^mg/1

               Alkaline  cleaners                      750
               Acid cleaners, dips                    750
               Cyanide plating                       37
               Copper plating                        37
«'              Chromium  plating                       15
               Nickel plating                        37
               Chromium  bright dip                    15
               Chromate  passivating                350-750


          A  problem  not  considered in proposing a maximum dissolved
          solids in the  final rinse, is the dragin   of  these rinses
          into  a  subsequent processing  operation.    If   the dragin
          attained from  the concentration proposed is  deleterious  to
          the  following processing  operation, the dissolved solids  in
          the final rinse would  have to  be decreased   or   means  for
          purification provided.

          The   following   is   an   example,    using   various  rinse
          combinations,  of  the reduction in water volume that can  be
          obtained for rinsing assuming that the dragout and the rinse
          water  mix immediately. A Watts-type  plating bath typically
          contains 270,000  mg/1  of total dissolved solids.    Obtaining
          37 mg/1 in the final rinse requires 27,600 (7300 gallons)  of
          rinse  water  if   a single  rinse tank is used, in order  to
          dilute 3.78 liters  (1 gallon)   of   a Watts-type plating
          solution  containing  270  g/1 of  dissolved solids.  The  same
          degree of dilution in  a final rinse  tank   may be  obtained
          with less water by use  of  series  and counterflow arrangement
          of  two  or more rinse tanks. If the tanks  are arranged  in
          series and fresh  water  is  fed in  parallel  to   each  tank  in
          equal volume,  the ratio, r of rinse water  to  dragout is:

                                           1
                                           n
                                        Co
                                r =  n   CF  ,
•
          where  Co = concentration  in  the  process solution
                 CF = concentration  in  last rinse tank  and
                 n  = number of  rinse tanks.
                                          125

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If the tanks are arranged in the same way, but flow proceeds
from   the   last   rinse  tank  to  the  first  rinse  tank
(count erf low) ,

                              1
                              n
                          Co
                    r =   CF

By feeding water to counterflow tanks instead of in  series,
the   reduction   in  water  varies  n-fold.   Values  of  n
calculated for several rinsing combinations,  using  the  Co
and CF values given above for a nickel bath are as follows:
	Rinse Combination	           Rinse_Ratiof r

Single rinse                                 7300

Two rinses, parallel feed                     171

Three rinses, parallel feed                    58.3

Two rinses, counterflow feed                   85.5

Three rinses, counterflow feed                 19.5
There is a significant reduction in water use by addition of
a  second  rinse  tank,  and at least two rinse tanks can be
considered normal practice.  These should  best  be  fed  in
counterflow.    Counterflow   rinse   tanks   increase   the
concentration of a metal or other constituent in  the  first
rinse tank following the plating or process bath.  The water
in  the first rinse tank can be used to supply makeup  water
for the plating bath.  As the  concentration  in  the  first
rinse  tank  increases, more of the dragout from the plating
bath can be returned to the bath in the  makeup  water,  and
less  will  require  treatment and disposal.  Therefore, the
addition of countercurrent rinse tanks can decrease both the
volume of water to be treated and the  amount  of  dissolved
metal  that  must  be  removed,  at  least in some cases.  A
problem not considered in using counterflow rinses  is  that
the concentration in the first rinse tank can become so high
that  the  diffusion  of  the  dragout  from the film on the
workpiece can be slowed  considerably  and,  therefore,  the
rinsing  efficiency decreased substantially.  Therefore, the
more countercurrent rinse tanks  that  are  used,  the  less
                                 126

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accurate  is  the  calculation assuming that the dragout and
rinse water mix immediately.

The rate of evaporation from the plating bath is a factor in
determining how much makeup water must be added.   Operating
a  bath  at  a  higher  temperature  will  allow more of the
dragout  to be returned to the bath because  of  the  higher
rate  of  evaporation.   However, the temperature at which a
bath may be operated is sometimes  limited  because  of  the
decomposition of bath components.  Progress has been made in
developing   bath   components   that   allow   higher  bath
temperatures to be used.  For example, brighteners for  zinc
cyanide baths have been developed which allow bath operation
at  50°  C  (120°  F) as compared to 32« C (90° F) .  The new
brighteners permit the return of more of the dragout to  the
plating  bath  and  a  lessened  load on the waste treatment
system, in addition to what other processing advantages they
may offer.

Advanced Treatment Technologies

Ion Exchange

Applicability..  Ion exchange is currently a  practical  com-
mercially  accepted  method  for the in-process treatment of
(1) raw water, (2) processing baths, (3) rinse waters.   Raw
water  is treated to provide deionized water for both makeup
and critical final rinsing operations.   Plating  baths  are
treated  to  remove impurities, i.e., removal of nickel ions
from a chromic acid  bath  with  a  cation  exchange  resin.
Rinse  waters  are  treated  to  provide  water  that can be
returned  to  the  process   solution.    The   concentrated
regenerant  can  be  chemically treated more easily than the
original volume  of  rinse  water  and  in  some  cases  the
chemicals  can  be  recovered and returned to the bath.  The
in-process  treatment  of  chromium   and   nickel   plating
effluents  by  ion-exchange  techniques are the more econom-
ically  attractive  treatment  operations  currently   being
carried  out.    Ion  exchange  also  is  beginning  to  find
increased use in combination with  evaporative  and  reverse
osmosis  systems  for the processing of electroplating rinse
waters.
Advantages ^and^ Limitations.  Some advantages of ion exchange
for treatment of plating effluents are as follows:

      (1)   Ion exchange is an economically attractive
           method for the removal of small amounts
           of metallic impurities from rinse waters
           and/or the concentration for recovery
                                127

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           of expensive processing chemicals.

      (2)   Ion exchange permits the recirculation
           of a high-quality water for reuse in the
           rinsing operations, thus saving on water
           consumption.

      (3)   Ion exchange concentrates processing bath
           chemicals for easier handling, treatment,
           subsequent recovery, or disposal operations.
Some  limitations  or  disadvantages  of  ion  exchange  for
treatment of process effluents follow:
      (1)   The limited capacity of parallel bed ion
           exchange systems means that relatively
           large installations are necessary to provide
           the exchange capability needed between
           regeneration cycles.  Continuous ion exchange
           units reduce the size compared to dual-bed
           units.

      (2)   Parallel-bed ion exchange systems require
           periodic regeneration with expenditures
           for regenerant chemicals.  Unless regeneration
           is carried out systematically or continuous
           ion exchange units are used, leakage of
           undesirable components through the resin
           bed may occur.  In addition, the usual
           treatment methods must be employed to
           dispose of the regenerated materials.

      (3)   Cyanide generally tends to adversely affect
           the resin performance because of tightly
           held metal cyanide complexes on strongly
           basic anion resins, so that processing of
           cyanide effluents  (except for very dilute
           solutions) does not appear practical at
           the present time.

      (U)   Resins, which are not highly cross-linked
           (or macroreticular), slowly deteriorate with
           use under oxidizing conditions.

Process  Principles	and Equipment.  Ion exchange involves a
reversible interchange of ions between a solid phase  and  a
liquid  phase.   There is no permanent or substantial change
in the structure of the solid resin particles.  The capacity
                              128

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Waste from
contaminated
rinse overflow
Waste-water
 reservoir
                                                           To clean water
                                                           reservoir and
                                                           process rinse tanks
                                                                        Caustic
                                                                         soda
                                                                      £x
• Hydrochloric
    acid
rtx
                                                                  LO
                                                                 To recovery
                                                                 or waste
                                                                 treatment
            FIGURE 8 ., SCHEMATIC PRESENTATION OF ION-EXCHANGE APPLICATION
                       FOR PLATING-EFFLUENT TREATMENT(7,25)

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of an ion exchange material is equal to the number of  fixed
ionic  sites  that  can enter into an ion exchange reaction,
and is usually expressed as  milliequivalents  per  gram  of
substance.    Ion   exchange   resins  can  perform  several
different operations  in  the  processing  of  waste  water,
including:

      (1)   Transformation of ionic species
      (2)   Removal of ions
      (3)   Concentration of ions.

The performance of some of these functions is illustrated in
Figure  8,  which is a generalized schematic presentation of
the application of ion exchange  to  treatment  of  electro-
plating effluents.  In practice, the solutions to be treated
by ion exchange are generally filtered to remove solids such
as   precipitated   metals,   soaps,   etc.,   which   could
mechanically clog the  resin  bed.   Oils,  organic  wetting
agents,   brighteners, etc., which might foul the resins, are
removed by passage through catrbon filters.

During processing, the granular ion exchange  resin  in  the
column  exchanges  one  of  its ions for one of those in the
rinse water or other solution being treated.   This  process
continues  until  the  solution  being  treated exhausts the
resin.  When this happens, solution flow is  transferred  to
another  column  with fresh resin.  Meanwhile, the exhausted
resin is regenerated by another chemical which replaces  the
ions given up in the ion exchange operation, thus converting
the  resin  back  to its original composition.  With a four-
column installation  consisting  of  two  parallel  dual-bed
units, as shown in Figure 8, the ion exchange process can be
applied  continuously  by  utilizing  the  regenerated units
while the exhausted units are being regenerated.

Most ion exchange systems depend upon regenerating with acid
and base to form the acid  and  base  forms  of  the  resin.
These  are  capable  of exchanging with and thereby removing
from solution both metals and dissolved salts such as sodium
chloride.   However, resins can be  regenerated  with  salts,
i.e.,  sodium  chloride to form sodium and chloride forms of
the resin.  These will exchange  with  metals  but  not  the
soluble  salts.   Since  exchange  capacity  is reserved for
metals only, the frequency of regeneration is  decreased  as
is the cost  of metal removed.

Practical  Operating  Systems.  The Phase I report described
systems in use to remove nickel ions and trivalent  chromium
ion  from chromium plating baths.  The more dilute baths for
producing chromium  conversion  coating  are  treated  in  a
                               130

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similar  manner  to  remove, zinc ions.  Aluminum is removed
from chromic acid anodizing baths, and from phosphoric  acid
baths  used  for  bright  dipping.   Cyanides  may  also  be
removed, in a 3-bed system, consisting of  strongly  acidic,
weakly basic, and strongly basic ion exchangers.  The system
provides  ease  of regeneration and little chance of cyanide
leaking  through5*.   The  three-bed  system  has  been   in
commercial  operation in Europe and only recently introduced
in the US.  Several of the systems are being  installed  one
of  which will be supported to a limited extent under an EPA
grant to obtain performance and economic information.

Demonstration Status.  An ion exchange system using a  short
30-minute  cycle,  including  a  3  to 4-minute back wash to
recover chromic acid from rinse waters has been in operation
for  over  a  year.   The  resin   undergoes   very   little
performance  deterioration  since  the  chromic  acid is not
deeply absorbed into the resin during such a short cycle.

Another system under development uses an ion exchange column
to achieve separation of components in much the same  manner
that  chromatographic  columns  are  used.   For  example, a
solution  for  bright  dipping   of   aluminum,   containing
phosphoric acid and aluminum ions, is fed through a strongly
basic ion exchange column.  The phosphate ions interact with
the  ion  exchange  sites and flow of the phosphoric acid is
retarded in comparison to that of the aluminum  ions,  which
flow  unimpeded  through  the  column.   Water, which may be
considered a very weak base, is  adequate  for  regenerating
the  ion exchange resin and eluting the phosphoric acid with
much of  the  aluminum  removed.   The  phosphoric  acid  is
returned to the brightening bath.

Evaporative Recovery

Applicability.   When  rinse  water from one type of bath is
distilled in an evaporative unit,  the  concentrate  may  be
returned  to the plating bath and the distillate to the cor-
responding rinse tank, which is useful for closing the  loop
on   a   single   plating   operation.    The  economics  of
distillation, from the standpoint of  either  investment  or
operating  costs  imposes  a constraint on the size range of
distillation equipment.  Units with a capacity of the  order
of 300 gph are used in practice.  Such a low rate of flow of
rinse  water  is achieved in many plating operations only by
the use of at least three countercurrent  rinses,  which  by
itself  reduces the waste water.  Evaporative recovery units
for all of the rinse cycles would  reduce  the  effluent  to
zero.   So  far, recovery units have been installed on rinse
tanks following plating baths in order  to  recover  plating
                              131

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chemicals  and  return  them  to the bath and thereby reduce
plating costs.  The units have not been installed on cleaner
or acid dip lines because  the  cost  of  chemicals  is  not
sufficient  to make recovery worthwhile, and the build up of
contaminants, i.e., oil and grease, makes use  of  a  closed
system difficult.

Evaporation is a firmly established industrial procedure for
recovering  plating  chemicals  and water from plating waste
effluents.  Commercial  units  for  handling  zinc,  copper,
nickel,  chromium,  and  other metal plating baths have been
operating successfully and economically for periods  of  one
to  10  years  or  longer.   Packaged  units for evaporative
treatment  of  plating  wastes  are  available   from   some
manufacturers.

At  least  100  evaporative units have been installed, which
means that their use in industry is limited to a very  small
percentage of the shops.  Nevertheless, announcements of new
installations  and  savings through their use keep recurring
and evaporative recovery appears to be a  method  that  will
grow  in  use.   However,  if  these  units  are  to pay off
strictly on the basis of savings in chemicals  such  factors
as  value  of  the  chemicals,  their  concentration  in the
process  bath,  and  the  dragout  rate  are  important   in
determining whether a savings is possible

Advantages	and _Limitations.  The following are some of the
advantages of using evaporation for handling  plating  waste
effluents:

       (1)  Recovers expensive plating chemicals, which
           were either lost by discharge to a sewer or
           effluent which would have to be treated or
           destroyed prior to disposal; chemicals
           concentrated to plating strength can be
           returned to the plating tank.

       (2)  Recovers distilled water for reuse in the rinse
           operations, thus lowering water and sewer
           disposal.

       (3)  Eliminates or greatly minimizes the amount of
           sludge formed during chemical treatment and
           eliminates or reduces the amount requiring
           disposal by hauling or  lagooning.

       (H)  The use of vacuum allows evaporation to accur
           at relatively low temperatures  (e.g., 110°F)
           so that destruction of  cyanides or other heat-
                               132

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           sensitive materials is lessened.

      (5)   The technology of evaporators (conventional and
           vapor recompression units) is firmly established,
          so their capabilities are well known and their
           performance should be readily predictable and
           adaptable to plating effluent handling.

Some  of  the  limitations  or  disadvantages of evaporative
recovery systems are given below:

      (1)   The rinse water saving (e.g., 1100 1/hr (300 gph))
           is rather small, and by itself does not signifi-
           cantly lighten the rinse water load on the final
           chemical treatment plant.

      (2)   Evaporative units have relatively high capital
           and operating costs, especially for the vacuum
           units.  Steam and coolant water are required.

      (3)   The evaporative units are fairly complex and
           require highly trained personnel to operate
           and maintain them.

      (4)   Separate units are required for handling the
           waste effluent from each line, since various
           solutions, such as zinc, nickel, copper,
           chromium, cannot be mixed for chemical
           recovery.

      (5)   As with all closed-loop systems, evaporation
           in most cases results in a build-up of impurities
           which must be taken care of by a bleed stream
           or directly in the closed-loop system.

The  advantages  offered  by  evaporative   recovery   often
outweigh  the  disadvantages.   Evaporative  recovery  is  a
promising method currently available  for  handling  plating
waste  effluents  and  limiting treatment plant size.  Where
existing chemical treatment  (cyanide  destruction,  chromate
reduction,   and   chemical  precipitation)  facilities  are
operating  at  less  than  capacity,   the   economics   and
practicality of installing new evaporative equipment must be
closely  evaluated.   The  small decrease in the rinse water
effluent  (e.g., 1100 1/hr (300  gph))  by  itself  does  not
warrant  the  installation  of  an  evaporative system.  The
savings produced by the recovery of plating chemicals  plays
the  significant  role  in judging the overall merits of the
evaporative system for a specific operation.
                               1-33-.

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Process Principles and Equipment.  A  representative  closed
loop  system  for  recovery  of  chemicals  and water from a
plating line with a single-effect  evaporator  is  shown  in
Figure 9.  A single-effect evaporator concentrates flow from
the  rinse  water  holding  tank.   The  concentrated  rinse
solution is returned to the  final  rinse  tank.   With  the
closed-loop  system, no external rinse water is added except
for makeup of atmospheric evaporation losses.  The system is
designed for  recovering   100  percent  of  the  chemicals,
normally lost in dragout, for reuse in the plating process.

Single-,   double-,  and  multiple-effect  evaporators,  and
vapor-recompression evaporator units are used  for  handling
plating effluent.  Open-loop and combined evaporation  (i.e.,
evaporation  combined with ion exchange, reverse osmosis, or
other  systems)  are  also  employed  for  handling  plating
effluent.

A  single-effect  evaporator  is  preferred,  if  relatively
untrained operating personnel are involved, or  low  initial
capital  outlay is desired.  It's the simplest in design and
therefore the easiest  to  operate.   However,  it  is  less
economical  than a double-effect or vapor recompression unit
with regard to utility costs.   A  double-effect  evaporator
should  be  considered  when lower operating cost is desired
with a modest increase in capital investment.

A vapor-recompression evaporator should be considered if  no
steam  or cooling water is available.  Where utilities for a
conventional  steam  evaporator  are  available,  the   high
initial   cost  of  the  vapor  recompression  unit  is  not
economically justified.  Its operating cost is the lowest of
the three systems.   Its  dependence  on  an  expensive  and
complex mechanical compressor is the main disadvantage.

Some  sources  report considerable maintenance and down time
and have dispensed with  use  of  evaporator  units.   Other
sources  report  little or no trouble and are very satisfied
with the operation.  It appears that the units  can  perform
very   satisfactorily   if   the  installation  is  properly
engineered,  and  if  preventive  maintenance  and  trouble-
shooting are carried out by knowledgeable personnel.

In  some  instances,  evaporation procedures must be used in
combination with chemical  or  other  methods  in  order  to
handle   small   amounts   of   impurity   build-up    (e.g.,
brighteners, carbonates, extraneous  metal  ions,  etc.,  in
closed  loop  operation) or for treatment of minor bleed-off
streams (open-loop).
                               134

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 Concentrate hold tank
                           Distillate hold tank
I       Plating work travel	»•

Plating bath                  Rinse tanks (2
    Rinse water
    holding tank
                                          IlSLJr
                              Condenser
                   Separator
         Recirculafion concentrate pump
                                       Vacuum jet
                                         C.W. out
                                             CW. in
                                             Reboiler
                                          Steam
                                                  Distillate pump
                                          Condensate
FIGURE 9   REPRESENTATIVE CLOSED-LOOP SYSTEM FOR
            RECOVERY OF CHEMICALS AND WATER  WITH
            A SINGLE-EFFECT EVAPORATOR
                        135

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Atmospheric evaporation, which uses air flow through packing
media in an evaporator,  can  concentrate  plating  solution
such as chromic acid up to 480 g/1 (H Ib/gal).

The  Corning  Glass company has introduced a new concept for
evaporative recovery.  A glass shell and tube heat exchanger
is mounted vertically and the solution is  fed  through  the
bottom.   The  boiling  causes  liquid surges that produce a
"rising film" effect and an improvement  in  heat  transfer.
Vapor  and  liquid  overflow  the  top  of the tubes and are
separated in a cyclone.  Water with less than  0.05  ppm  of
chromic  acid  has been produced from chromium plating rinse
water.

Practical Operating Systems.  Systems  operating  on  copper
cyanide,  nickel,  chromium,  and zinc cyanide plating lines
were described in the Phase I  report.   Systems  have  also
been  installed  on  lines  using the following baths: brass
cyanide, cadmium cyanide, Pb-Sn-Cu fluoroborate,  and  gold.
The  practicality  of  using this system on cadmium and lead
plating baths means there is at least one way of eliminating
discharge of polluted water  from  these  processes.   Small
amounts  of  spills, leaks, if segregated, are evaporated to
dryness, and the solid waste sent to a metal recovery  unit.
Falling  film atmospheric evaporators have been installed in
a few plants.

Demonstration  Status.   The  "rinsing   film"   units   are
undergoing pilot and plant test.

Reverse osmosis

Applicabi1ity«  Reverse Osmosis uses a pressure differential
across  a membrane to separate a solution into a concentrate
and a more dilute solution that may approach the  purity  of
the  solvent.   It  therefore  accomplishes the same type of
separation as distillation and has been applied  in  plating
installations in the same manner.  Small units under 300 gph
have  been  installed to recover plating baths chemicals and
make closed-loop operation of a line possible.

There are limitations  on  the  acidity  and  alkalinity  of
solutions  suitable  for  treatment  by reverse osmosis that
eliminate some alkaline baths and chromic  acid  baths  from
consideration unless modifications are made to the solutions
prior  to  treatment.  Another use of reverse osmosis is for
end-of-process water recovery following chemical  treatment.
A  recently  designed  system for Plant 11-22 offers promise
that large capacity reverse osmosis systems are possible and
therefore not subject to the* size constraints of evaporative
                                136

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systems.  If so, they should play a key role in  the  design
of plants that will have no liquid effluent.

Most  of  the development work and commercial utilization of
the reverse osmosis process, especially for desalination and
water treatment and recovery, has occurred during  the  past
10  years.  There is a steadily growing number of commercial
installations in plants for concentration  and  recovery  of
plating   chemicals  along  with  recovery  of  water  under
essentially closed-loop conditions.  Most  of  the  existing
commercial installations are for treatment of nickel plating
solutions,  since  reverse  osmosis is especially suited for
handling nickel solutions and also because of the  favorable
economics  associated  with  recovery and reuse of expensive
nickel chemicals.   commercial  reverse  osmosis  units  for
handling  acid zinc and acid copper processes also have been
installed, however.  Laboratory pilot plant  and  full-scale
in-plant  studies directed at handling cyanide and chromium-
type effluents are under way.

Reverse osmosis is  especially  useful  for  treating  rinse
water  containing  costly  metals and other plating salts or
materials.  Generally, the purified water is recycled to the
rinse, and the concentrated salts to the plating  bath.   In
instances where the concentrated salts cannot be recycled to
the  plating  tank,  considerable  savings  will be achieved
because of the reduced amount of waste-containing  water  to
be treated.

Advantages	and	Limitations.   Some  advantages  of reverse
osmosis for handling process effluents are  as follows:

       (1)  Ability to concentrate dilute solutions
           for  recovery of  salts and chemicals

       (2)  Ability to recovery  purified water for
           reuse

       (3)  Ability to operate under low power require-
           ments  (no latent heat or vaporization or
           fusion is required for effecting separa-
           tions; the main  energy requirement is for
           a  high-pressure  pump)

       (t»)  Operation at ambient temperatures  (e.g.,
           about 60° to 90° F)

       (5)  Relatively small floor  space requirement
           for  compact high-capacity units.
                                137

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Some limitations or disadvantages  of  the  reverse  osmosis
process for treatment of process effluents are listed below:

      (1)  Limited temperature range for satisfactory
           operation. (For cellulose acetate systems
           the preferred limits are 65° to 85° F;
           higher temperatures will increase the rate
           of membrane hydrolysis, while lower temper-
           ature will result in decreased fluxes but
           not damage the membrane).

      (2)  Inability to handle certain solutions
           (strong oxidizing agents, solvents and
           other organic compounds can cause dissolu-
           tion of the membrane) .

      (3)  Poor rejection of some compounds (some
           compounds such as borates and organics of
           low molecular weight exhibit poor rejection).

      (4)  Fouling of membranes by slightly soluble
           components in solution.

      (5)  Fouling of membranes by feeds high in sus-
           pended solids (such feeds must be amenable
           to solids separation before treatment by
           reverse osmosis).

      (6)  Inability to treat highly concentrated
           solutions (some concentrated solutions may
           have initial osmotic pressures which are so
           high that they either exceed available
           operating pressures or are uneconomical to
           treat).

Process   Principles  and  Equipment.   Water  transport  in
reverse osmosis (RO)  is opposite to the water transport that
occurs in normal osmosis, where  water  flows  from  a  less
concentrated  solution  to a more concentrated solution.  In
reverse osmosis, the more concentrated solution is put under
pressure considerably greater than the osmotic  pressure  to
drive  water  across the membrane to the dilute stream while
leaving behind  most  of  the  dissolved  salts.   Salts  in
plating  baths  such as nickel sulfate or copper sulfate can
be concentrated to solutions containing up to 15 percent  of
the sa.lt, by weight.

Membrane  materials  for  reverse osmosis are fairly limited
and the bulk of the development work has been with specially
prepared cellulose acetate membranes, which can operate in a
                                138

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pH range of 3 to 8 and are therefore  useful  for  solutions
that  are  not  strongly acid or alkaline, i.e., rinses from
Watts nickel baths.  More recently, polyamide membranes have
been developed that will operate up  to  a  pH  of  12,  and
several  of  these  units  are  operating  in plants for the
treatment of cyanide rinse waters.

Figure 10 is a schematic presentation of the reverse osmosis
process  for  treating  plating-line  effluent.   The  rinse
solution  from a countercurrent rinse line is pumped through
a filter, where any suspended solids that  could  damage  or
foul  the  membrane are removed.  The rinse solution is then
raised to the operating pressure by a high-pressure pump and
introduced into the reverse osmosis unit.  The  concentrated
salt  stream  is  returned  to  the  plating tank, while the
dilute permeate stream is returned to the second rinse tank.
Currently,  several  different  configurations  of  membrane
support  systems  are  in  use in commercial reverse osmosis
units.  These  include  plate  and  frame,  tubular,  spiral
wound, and hollow fine fiber designs.

Practical .Operating _Systems.  Reverse osmosis units are in
operation for recovering  nickel  from  rinse  waters.   The
concentrate is returned to the plating bath.

Demonstration	Status.   The reverse osmosis units installed
at the Rock Island Arsenal  as  part  of  an  end-of-process
water  recovery  system,  is currently undergoing full scale
testing of performance as part of a  total  waste  treatment
system.   A project sponsored by the American Electroplating
Society has demonstrated that  cellulose  acetate  membranes
can  operate successfully on nickel and copper sulfate rinse
waters and that spiral  wound  and  hollow  fiber  polyamide
membranes  can  be  used  to treat copper, zinc, and cadmium
cyanide  baths.    A  second  phase  of  this  study   is   a
demonstration  in  a  plating  shop  of a full scale reverse
osmosis system on copper cyanide rinse water.

Freezing

Applicability.   The freezing process  would  be  capable  of
recovering  metal  and water values from plating rinse water
to permit essentially closed-loop type  operation  if  fully
developed.   The feasibility of using freezing for treatment
of plating rinse waters was  demonstrated  on  a  laboratory
scale  using a mixed synthetic solution containing about 100
mg/1 each of nickel,  cadmium, chromium, and zinc, along with
30,000 mg/1 of sodium chloride.  Greater  than  99.5  percent
removal   of   the   metallic   ions  was  achieved  in  the
experiments,  with the purified water product containing less
                              139

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                                      Rinse
                                        1
=  High-
p pressure
   pump
                                                                                  Parts
 Low-pressure
   pump
Makeup
water
            Concentrate
Reverse-osmosis
    unit
                                                      Permeate
FIGURE 1° SCHEMATIC DIAGRAM OF THE REVERSEOSMOSIS PROCESS
            FOR TREATING PLATING EFFLUENTS

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than 0.5 mg/1 each of the individual  plating  metals.   The
separation tests were carried out using the 9500 1/hr (2500-
gpd)  pilot plant unit at Avco Systems Division, Wilmington,
Massachusetts.

Process  Principles  and  Equipment.   The  basic   freezing
process for concentration and recovery of water from plating
effluents  is  similar  to  that  used for recovery of fresh
water from the sea.  A schematic diagram of the treatment of
plating rinses by the freezing process is  shown  in  Figure
11.   The  contaminated reuse water is pumped through a heat
exchanger (where it is cooled by melted product  water)   and
into  a freezer.  An immiscible refrigerant (e.g., Freon)  is
mixed with the reuse water.  As the refrigerant  evaporates,
a  slurry  of  ice and concentrated solution is formed.   The
refrigerant vapor is  pumped  out  of  the  freezer  with  a
compressor.   The  slurry  is  pumped  from the freezer to a
counterwasher, where the concentrated solution  adhering  to
the ice crystals is washed off.

The  counterwasher  is  a  vertical  vessel  with a screened
outlet located midway between top and bottom.  Upon entering
the bottom, the slurry forms a porous  plug.   The  solution
flows  upward throught the plug and leaves the counterwasher
through the screen.   A   small  fraction  of  the  purified
product  water  (less than 5 percent) flows countercurrently
to the ice plug to wash off concentrated  solution  adhering
to  the ice.  The ice is pumped to a condenser and melted by
the release of heat from the  refrigerant  vapor  which  had
been originally evaporated to produce the ice, and which had
been  heated  by  compression  to  a  saturation temperature
higher then the melting point of the ice.

Because of the pump work, compressor  work,  and  incomplete
heat  exchange, a greater amount of refrigerant is vaporized
than can be condensed by the melting ice.   Consequently,   a
heat   removal   system   is   needed  to  maintain  thermal
equilibrium.  This system consists  of  a  compressor  which
raises the temperature and pressure of the excess vapor to a
point where it will condense on contact with ambient cooling
water.

The  freezing  process  offers  several advantages over some
other techniques.    Because  concentration  takes  place  by
freezing   of   the   water   in  direct  contact  with  the
refrigerant,  there  is  no  heat-transfer  surface  (as  in
evaporation)  or  membrane  (as  in  reverse  osmosis)  to be
fouled by the concentrate or other contaminants.   Suspended
solids  do  not  affect the freezing process and are removed
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                                                  Cooling
                                                   water
To rinse
 tank
                                                                                        Compressor

                                                                                        Refrigerant
                                                                                         vapor
             Heat exchanger
                FIGURE 11 SCHEMATIC DIAGRAM OF FREEZING PROCESS FOR RECOVERY
                           OF WATER AND CHEMICALS FROM PLATING RINSES (37,38)

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only as required by the end use to be made of the  recovered
products.

The  heat  of  crystallization  is  about  1/7  the  heat of
vaporization,  so   that   considerably   less   energy   is
transferred  for  freezing than for a comparable evaporation
operation.  Because freezing is a  low-temperature  process,
there  will  be  less  of  a  corrosion  problem  than  with
evaporation, and less expensive  materials  of  construction
can   be  employed.   The  freezing  process  requires  only
electrical power, as  opposed  to  the  evaporation  process
which also requires steam generating equipment.  The cost of
the  freezing  method  may  be only 1/3 that for evaporative
recovery.

A method of freeze drying electroplating solutions has  been
demonstrated  in  the laboratory.  Droplets of the solutions
are  injected  into  cold  liquid-hexane  where   they   are
immediately frozen.  The droplets were separated out and the
water removed at subfreezing temperature.  The method leaves
a  dry  chemical residue, and the pure vaporized water could
be recycled to process.  The economics of the process  on  a
practical scale are unknown.

Practical	Operating, Systems.  No commercial utilization of
freezing"?or treatment of~waste water from electroplating is
known at this time.

Demonstration Status.  No demonstrations are in progress  in
electroplating  plants.   However,  a  9500 liters/day (2500
gpd) unit is in operation  to  demonstrate  desalination  of
water.

Electro dialysis

Applicability.   Electrodialysis  removes  both  cations and
anions~from solution and is most effective with multi-valent
ions.  It is capable of reducing the concentration of  metal
ions  from  solutions  whether  they  are  complexed or not.
Chromate and cyanide ions may also be removed.

Process   Principles   and    Equipment.     The    simplest
electrodialysis system consists of an insoluble anode and an
insoluble  cathode  separated by an anion permeable membrane
near the anode and a  cation  permeable  membrane  near  the
cathode.   An  anode  chamber,  cathode  chamber, and middle
chamber are thereby formed.  Upon electrolysis  anions  pass
from the middle chamber to the anode compartment and cations
pass  from  the  middle  chamber to the cathode compartment.
The concentration of salt  in  the  central  compartment  is
                                 143

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thereby  decreased.   By  employing several anion and cation
permeable membranes between the electrodes several  chambers
are  created.   A  stream may then be run through several of
these chambers in which the  concentration  is  successively
increased.    The  net  effect  is  similar  to  that  of  a
continuous moving bed ion exchange  column  with  electrical
energy used for regeneration rather than chemicals.

Practical Operating Systems.  No practical operating systems
have  been  reported.   However, development has resulted in
several demonstrations, discussed below.

Demonstration Status.   Several  demonstrations  have  shown
that   electrodialysis   is  a  promising  method.   Further
development and use of the method may be  expected.    Copper
cyanide  rinse  water may be concentrated sufficiently to be
returned to  the  bath  by  using  two  units  on  a  double
counterflow  rinse system i.e., between the first and second
rinse tank and  between  the  bath  and  first  rinse  tank.
Copper  may  be  recovered and chromic acid regenerated in a
spent etching solution  for  printed  circuits.   The  Metal
Finishers Foundation has put priority on a future project on
cyanide removal by electrodialysis.

Ion-Flotation Techniques

Applicability.    Ion-Flotation  techniques  have  not  been
developed for application to process rinse water  effluents.
If  successfully  developed  into  a  practical  method  for
effluent treatment, ion flotation  offers  possibilities  of
reducing the amount of water discharged by 60-90 percent for
some  operations.   These  savings  are  based on results of
small-scale  laboratory  studies  on  solutions   containing
cyanides or hexavalent chromium.

Process  Principles	and Equipment,  Separation of ions from
aqueous solutions by a  flotation  principle  is  a  concept
first  recognized  about  25  to  30 years ago.  In the ion-
flotation  operation  a  surface  active  ion  with   charge
opposite  to  that of the ion to be concentrated is added to
the solution and bubbles of air or other gas are  introduced
into  the  solution  to  form  a froth of the surface-active
materials.  The foam is separated and collapses  to  form  a
scum  containing an ion concentrate.  Ion flotation combines
the technologies of mineral flotation and ion  exchange.   A
schematic  diagram  of  an  ion-flotation  cell  is shown in
Figure 12.

Experimental  results  indicate  that  90  percent  of   the
hexavalent  chromium  in  a  10  to  100 ppm solution can be
                               144

-------
Air in

-— 6 	
Foam concentrate
take-off
Purified
solution — » 	
removal
Tnjprtiop port
for collector 	 ^-
agent


0 *
t) 0
0 6
6 0
o\ f
t>( 0 t
I
0

•-•^y— • -,^_^
1^-— ~- *»>-V
*-*">^— ^/II-'-N'""
-^/"s*-^X-^V
Q A
» /
t o
o 0
at
K;
t
,—-•—
_^-*--
-^^^-«
if— NtftH
)
)
Air out

—^^*
*^*^*
~-«^*
— Foam level
— Solution level
v/ ' Solulion sumpliny
poi 1
FIGURE 12 SCHEMATIC DIAGRAM OF ION-FLOTATION CELL
          FOR TREATMENT OF PLATING EFFLUENT
                     145

-------
 removed with primary amine  surface-active agents.    However,
 the  amine  suffered  deterioration when  regenerated  for reuse,
 since  the  removal efficiency  dropped to  60 percent after two
 regenerations of the amine.

 Grieves,   et al., have  demonstrated  the  feasibility of using
 ion  flotation on   dichromate  solutions  with  a  cationic
 surfactant   (ethylhexadecyldimethylammonium   bromide) .    A
 continuous operation with a retention  time of   150  minutes
 was    devised.   The   feed   stream  contained   50  mg/1  of
 dichromate.   Approximately 10 percent  of the  feed  stream was
 foamed off to produce a solution  containing U50  mg/1  of
 dichromate,  while the stripped solution  contained  15 mg/1.

 Cyanides   have been removed from dilute  solutions  with mixed
 results.   The  extraction efficiency  from a cadmium  cyanide
 solution   containing 10 ppm of cyanide was 57 percent,  using
 primary, tertiary,   and quaternary  ammonium compounds  as
 collectors.    Extraction  efficiencies  for  nickel and iron
 cyanide solutions were  approximately 90  percent,   but  these
 systems are  of relatively little interest.

             Operating  Systems.   There  are no   practical
operating systems.

Demonstration Status.  The process has not been demonstrated
in an operating plant.

Electrolytic Stripping

AEEiisabiJLity.  Electrolytic stripping is not in general use
for removing  metals  although  some  procedures  have  been
employed for recovering precious metals.

Process Principles and Equipment.  in order to strip a solu-
tion  by electrodeposition it. is necessary that the metallic
ions in a dilute solution reach the  cathode  surface  at  a
sufficient  rate  so that essentially all of the ions can be
deposited in a reasonable time.  Surfleet  and  Crowle  have
discussed several methods of accomplishing this.  One method
called  the  "integrated"  system  uses baffles in a tank to
create a very long path  through  which  the  water  may  be
recirculated  at  a  high  velocity.  The method is suitable
only for metals having a relatively  high  limiting  current
density for dilute solutions, such as gold, silver, and tin.
The  fluidized  bed  electrode  is a bed of metal spheres or
metal-coated glass spheres that is fluidized by pumping  the
dilute  solution through it and causing an expansion of 5 to
10 percent.   With spheres of 100 to 300 microns in diameter,
a total geometric area of 75 cm2/cm3 is obtained.  Thus, the
                             146

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current density is very low  and  the  flow  of  electrolyte
through  the  bed  provides the forced convection to support
high currents.  Another system employs  electrodes  made  of
expanded  metal  and  the  turbulence  around this structure
enhances the rate of deposition of metal  when  solution  is
pumped  past  it.  Turbulence and an increase in the rate of
deposition at a plane electrode  may  also  be  promoted  by
filling  the  space  between electrodes with a woven plastic
screen, glass beads, etc.

In another system the electrode is introduced into a  narrow
gap  between  two porous carbon electrodes.  The bulk of the
solution (99%) is forced through the cathode where copper is
deposited out.  Predeposited copper on the anodic  electrode
is  dissolved  into  the  1  percent of the electrolyte that
permeates through this electrode and a copper concentrate is
produced.  The two electrodes are periodically  reversed  so
that  copper  deposited  from  a large volume of solution is
dissolved into a small volume  of  electrolyte.   Copper  in
solution  has been reduced from 670 mg/1 to 0.55 mg/1 in the
cathode stream and concentrated  to  4U  g/1  in  the  anode
stream.   A  similar  system  has  been  used for depositing
metallic impurities from strong caustic solutions.

Practical O]3e rating ^Syst ems.   There  are  many  systems  in
operation for the recovery of precious metals.

Demonstration  Status.   The  porous  electrode system 76 is
still under development at the University of California  and
has  been  scaled  up  to  handle  250 gpd of copper sulfate
solution.  The Metal Finishers  Foundation  has  established
priority  for  a future project to remove zinc from effluent
by electrodeposition.

Water Conservation by Carbon Adsorption

Applicability.  Activated  carbon  has  been  used  for  the
adsorption  of  various  materials  from solution, including
metal ions.  Experimental data show that up to 98 percent of
the chromium can be removed from waste water.   The  treated
water can be recycled to the rinse tanks.
                  §  and Eguipjnent.  The process relies upon
the adsorption of metal ions on specific types of  activated
carbon.   In the case of Chromium VI, a partial regeneration
of the carbon can  be  accomplished  with  caustic  solution
followed  by  an  acid  wash  treatment  to  remove residual
caustic  and  condition  and  carbon  bed   for   subsequent
adsorption  cycles.  The equipment consists of holding tanks
for the raw waste, pumps and piping to circulate  the  waste
                             147

-------
through  adsorption  columns  similar  to those used for ion
exchange.

Practical Qperating^Systems.  Systems  based  on  adsorption
and desorption are still under laboratory development and no
practical operating systems are known.

Demonstration.  Status.   Pilot  plant  equipment  has  been
operated successfully in an  electroplating  plant  treating
chromium  rinses  at a flow rate of 19 liters/min (5 gpm)  at
concentrations from 100 to  820  mg/1  hexavalent  chromium.
Adsorption   was   continued   until  the  effluent  reached
concentrations of 10 ppm of Or*6.

Liquid-Liquid Extraction

Applicability. Liquid-liquid extraction has been used on  an
experimental  basis  only  for  the extraction of hexavalent
chromium from waste waters.   The effect is  to  concentrate
impurities  in  a smaller volume, which in turn will have to
be treated by other means  or  suitably  disposed  of.   The
fully  extracted  aqueous phase may be recycled to the rinse
tanks.  Water savings from 50 to 73  percent  appear  to  be
possible.

Process	Principles	and Equipment.  The metal-ion pollutant
is reacted with an organic phase  in  acid  solution,  which
separates  readily  from the aqueous phase.  Metal is subse-
quently stripped from the organic  phase  with  an  alkaline
solution.    Hexavalent  chromium,  for  example,  has  been
extracted from  waste  water  at  pH  2  with  tertiary  and
secondary  amines dissolved in kerosene.  After the reaction
of the chromium with the amine  and  phase  separation,  the
chromium is stripped with alkaline solution from the organic
phase  restoring the amine to its original composition.  For
liquid-liquid  extraction  to  be  feasible  the   following
conditions would have to be met:

      (1)  The extraction of chromium should be virtually
           complete

      (2)  Reagent recovery by stripping would be efficient

      (3)  The stripping operation should produce a
           greatly concentrated solution

      (U)  The treated effluent solution should be
           essentially free from organic solvents
                               148

-------
      (5)   Capital and operating costs should be
           reasonable.

The  equipment  required  consists basically of mechanically
agitated mixing and settling tanks, in which the phases  are
intimately  dispersed  in  one  vessel by agitation and then
permitted to flow  by  gravity  to  a  settling  vessel  for
separation.   Holding  tanks for extractant and stripper and
circulating pumps  for  these  solutions,  as  well  as  the
purified  waste water, are necessary.  Equipment for liquid-
liquid extraction would also include horizontal and vertical
columns, pulsed columns and centrifuges.

Practical  Operating  Systems.    Liquid-liquid   extraction
systems  are  not  known  to" be  operating for treatment of
electroplating wastes.

DemQnstration_Status«  Experimental  evidence  exists  indi-
cating that up to 99 percent of chromium can be successfully
extracted  from  rinse  waters containing 10 to 1000 mg/1 of
Cr*+.  With 10 ppm of Cr«+ in the rinse water,  the  treated
effluent  contained  as  little as 0.1 mg/1 of the ion; with
100 ppm in rinse water  concentration  was  reduced  to  0.4
mg/1.   Stripping  was  effective as long as the amines were
not allowed in contact with the  chromium  for  a  prolonged
period  of  time  which  would allow oxidation by Cr*+ ions.
The effluent, however, contained from 200  to  500  mg/1  of
kerosene, which is undesirable.

Methods of Achieving No Discharge^of Pollutants

Although  chemical  methods  of  treating  waste  waters are
achieving the  low  effluent  discharges  recorded  in  this
report,  they  are  not improvable to the point of achieving
zero  discharge  of  pollutants.    Also  the   problem   of
recycling  sludges  or  solid wastes remains.  It is easy to
design systems that will in principle close the process loop
and prevent discharge.  In practice, however, this can  only
be  done with considerable forethought and experience, since
closed systems are in general subject to  impurity  buildup.
Progress in achieving no-discharge systems is likely to take
place  in a series of steps in which the amount of discharge
is consistently reduced until it is negligible,

A major problem with a series of electroplating processes in
a closed cycle is that of dragin.   After a closed cycle has
been run long enough any  stagnant  tank,  i.e.,  a  plating
solution  that  is  normally not discarded, will contain the
same concentration of contaminant as the preceding  tank  in
the  cycle,  the  assumption being that the volume of dragin
                             149

-------
and dragout  are  equal.   Therefore,  if  the  final  rinse
following  nickel  plating  contains  12  ppm  of nickel and
chromium plating follows, the chromium bath will  ultimately
contain 12 ppm of nickel.  Nickel is frequently removed from
chromium  plating  baths  by ion exchange, but since the ion
exchanger requires  periodic  regeneration,  the  regenerant
must  somehow  be  returned  to  the  system  if it is to be
considered a closed one.  The nickel in the regenerant might
be recovered and  returned  to  the  nickel  bath,  but  the
dissolved  solids, i.e., sodium sulfate, and sodium chloride
are  really  excess  products  that  cannot  be   completely
returned to the process.  While the main process loop may be
closed,   the  secondary  purification  loops  may  be  more
difficult to close.  With some process baths, it may not  be
possible  to  find  a  method  for  purification  that is as
adaptable as is ion exchange to the removal of nickel from a
chromium  bath.   Alternatives  then  are  to  (1)   develop
processing  baths  that can tolerate the impurity buildup or
(2) to design rinse systems in which  the  concentration  of
impurity  in  the final rinse tank is reduced to a tolerable
level.

Some systems, designed to remove a  specific  impurity,  are
found  to remove other components as well, which may require
further treatment.  An example of such a system is that used
for  removing  carbonates  from  cyanide   baths.    Whether
freezing   or   precipitation  with  calcium  is  used,  the
carbonates occlude  and  adsorb  significant  quantities  of
cyanide  that  must then be further treated, with the result
that  cyanide  is  not  maintained  in  a   closed   system.
Therefore,  with present technology, it is likely that there
will be some discharge from a. process loop in spite  of  the
best  efforts  that  are made to close it.  Some waste water
effluent will be produced and the next consideration is  how
well a waste treatment system can be closed.

The  effluent will contain metals, cyanide, and chromate all
of which can be treated to relatively low levels to give (1)
liquid containing  small  amounts  of  metals,  cyanide  and
chromate and larger amounts of soluble salts such as sulfate
and  chlorides, and (2) sludge containing metals, phosphate,
carbonates, flocculating agents, etc.  The liquid, if  large
in  volume  may  be  concentrated  further  by  evaporation,
reverse  osmosis,  ion  exchange,  or  some  other   process
followed  by  a  further  purification  to  reduce the metal
effluent  to   a   negligable   value.    The   liquid   may
alternatively  be  passed through a salt loaded ion-exchange
column to remove all traces of heavy  metals  and  yield  an
effluent  containing  essentially  soluble salts that may be
discharged to the  ocean  if  not  to  a  stream  or  sewage
                           150

-------
facility.   Alternatively, solutions of soluble salts may be
evaporated to dryness and the solid salt contained or  fixed
in cement, etc.

Sludge,  obtained  either  directly from waste water or from
ion-exchange regenerants, cleaning and pickling baths, etc.,
would need to be reclaimed for metal  values  or  the  metal
salts  separated out for return to process tanks in order to
provide a closed or recycle system.

Thus, to attain the ideal of providing a system where  input
is  energy  and  materials  and  output is solely a finished
product  will  require  further  research  and  development,
considerable  ingenuity,  and expert engineering and design.
However, the capability for progressing towards this goal is
available.
                              151

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                        SECTION VIII
        gQ§T§x_gNERGYr AND NONWATER QUALITY ASPECTS


Introduction

In  this  section,  costs  associated  with  the  degree  of
effluent   reduction  that  can  be  achieved  by  exemplary
treatment  methods  are  discussed.   The  nonwater  quality
aspects  concerning  disposal  of solid waste and the energy
impact  of  the  waste  treatment  technologies   also   are
discussed.

Treatment and Control Costs

Chemical Treatment to Achieve Low Levels of Pollutants

BPCTCA Limitations (Table_l)_-  Costs associated with control
technology   consistent   with  the  exemplary  practice  of
chemical treatment in 32 plants averaged  $1.06/1000  liters
treated  with  a  standard  deviation  of  $1.91/1000 liters
(Table 28).  Operating costs include a cost of capital equal
to 8 percent of the investment and depreciation equal to  10
percent of the investment.

The  operating  cost of waste treatment as a percent of cost
of electroplating for 13 companies is  7.4  percent  with  a
standard deviation of 5.4 percent.  The figures were arrived
at  from  estimates  by the plants themselves concerning the
relative cost of waste treatment.

The  plot  in  Figure  13  shows  the  large  variation   in
investment  costs  for  individual  plants  and reflects the
large deviations reported above.  Thus, there are no typical
plants.  Rather,  costs  are  highly  dependent  upon  local
conditions.   Costs  were  calculated  in terms of volume of
waste  water  treated  rather  than  surface  area  finished
because costs are believed to be more closely related to the
volume  treated.   Water use is highly variable and relating
waste treatment costs to area finished would  have  provided
even  more  variable results.  For a nominal water use of 80
liters/sq m (2 g/sq ft) the cost  of  $1.06/1000  liters  is
equivalent to $0.085/sq m  ($.0079/sq ft).

In  addition  to  the  cost  data collected from plants with
waste treatment facilities, costs  were  also  estimated  by
modeling   electroplating  facilities  together  with  waste
treatment facilities  providing  effluent  that  would  meet
                            153

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                                           TABLE 28   COSTS FOR WASTE TREATMENT FACILITIES
Plant
No.
20-24
33-24
33-26
36-12
33-2
33-4
8-5
6-37
19-11
15-3
9-7
>-. 4~9
ol 4-5
** 30-19
8-8
33-22
33-23
20-22
20-20
33-35
20-23
4-8
6-35
9-2
23-7
36-13
33-30
19-24
6-36
31-16
46-4
33-29
Investment
Processes (1971)
Plating Common Metals
Plating Common Metals
Plating Common Metals
Plating Com. , Free. Metals
Plating Prec. Metals
Plating Prec. Metals
Plating Prec. Metals
Plating Prec. Metals
Plating Prec. Metals
Plating Prec. Metals
Electropainting, Anodizing
Electroless Plating
Electroless Plating
Electroless Plating
Electroless Plating
Anodizing
Anodizing
Anodizing
Anodizing
Anodizing
Anodizing
Chemical Milling
Chemical Milling
Chemical Milling 2
Chemical Milling
Chemical Milling
Phosphating
Etching
Immersion
Printed Circuits 1
Electropolishing
Elect romachining
34,000
172,000
27,932
200,000
25,000
66,000
300,000
400,000
110,000
66,113
100,000
45,325
23,292
217,725
51,679
193,846
167,575
180,902
155,300
125,000
123,414
17,469
300,000
,908,000
582,306
29,232
94,500
295,615
58,985
,050,000
41,926

Operating
Cost/Year
(1971)
14,195
80,430
10,694
72,809
14,968
18,205
115,995
121,905
49,985
25,552
32,249
45,312
9,746
168,312
13,430
51,515
49,658
113,370
84,481
28,244
41,855
16,675
83,758
685,867
333,216
11,119
59,726
120,211
15,702
237,623
14,368

Hours
Operated
Per Year
4,800
4,000
7,200
7,520
1,025
1,800
2,400
2,250
2,000
2,000
4,000
4,000
4,000
8,400
4,000*
4,000
6,000
6,000
7,200
7,200
6,000
4,800
2,000
6,000
6,000
3,850
3,600
2,000
2,250
4,000
4,170
4,000
Volume to
Treatment
Plant, 1/hr
26,497
15,897
4,163
6,813
12,615
24,224
34,065
113,562
45,424
57,727
30,851
1,741
3,985
104,087
36,794
9,000
18,925
79,485
129,447
3,028
22,712
7,570
7,570
189,250
159,000
6,813
54,509
6,813
11,356
90,849
30,659
22,710
Volume to
Treatment
Plant, 1/yr
1.271 x 108
6.359 x 107
2.997 x 10?
5.123 x 10?
1.293 x 10?
4.366 x 10?
8.176 x 10?
2.555 x 108
9.08 x 107
1.154 x 108
1.234 x 108
6.964 x 106
1.594 x 107
8.743 x 108
1.471 x 108
3.600 x 107
1.136 x 108
4.769 x 108
9.320 x 108
2.180 x 107
1.362 x 108
3.634 x 107
1.514 x 107
1.136 x 109
9.540 x 108
2.623 x 10?
1.962 x 108
1.362 x 107
2.555 x 107
3.633 x 108
1.278 x 108
9.084 x 107
Invest-
ment/
1/hr
$ 1.28
10.82
6.71
29.36
1.98
2.72
8.81
3.52
2.42
1.15
3.24
26.03
5.84
2.09
1.40
21.54
8.85
2.28
1.20
41.28
5.43
2.31
39.63
15.36
3.66
4.29
1.73
43.39
5.19
11.56
1.37

Operating
Cost/
1000 liters
$ 0.30
1.26
0.36
1.42
1.15
0.42
1.42
0.48
0.55
0.22
0.26
6.51
0.61
0.19
0.09
1.43
0.44
0.24
0.09
1.30
0.31
0.46
5.53
0.60
0.35
0.43
0.30
8.83
0.62
0.65
0.11

Treating
Cost/
Processing
Cost

14


3

6




5
0.65
7

7.5
13
4.7
16
3
7.4
1.0
18


1.6
4.4





* Assumed 16 hours per day, 5 days per week.

-------
                   4 u
U1
U1
                   to
                   i_
                   o
                   o
                   T3
                   in
                   O
c
0>
E

U)
o>
                       10
                                                       Capacity Liters.hr

                                 FIGURE 13    INVESTMENT COSTS OP  WASTE TREATMENT  PLANTS
                                              WITH VARYING VOLUME  CAPACITY

-------
BPCTCA  standards.   By  modeling  plants it was possible to
derive selfconsistent costs for various degrees of treatment
and for various plant sizes.  Plants were sized according to
the number of employees, which is desirable if data  are  to
be used for cost impact studies.  Tables 29 and 30 summarize
the results of one cost estimate.

The  lowest  investment  cost of $22,980 is for a 5-employee
urban plant that precipitates metals, does not treat cyanide
or hexavalent chromium, and does not  clarify.   This  plant
also  has  the  lowest  operciting  cost  of $12,29U/yr.  The
highest investment cost of $378,455 is for a plant  with  47
employees   carrying  out  complete  waste  water  treatment
including clarification and filtering of sludge.  This plant
also has the highest operating  cost  of  $157,894/yr.   The
operating cost probably could be reduced somewhat by using a
filter  press  directly  on  the  neutralized  waste  water.
However, this technology is not as well established as  that
of clarification.

Costs  per  area  are  $1.02/1000 liters for the 5-man plant
neutralizing only and $1.09/1000 liters for the 47-man plant
doing  complete  waste  treatment.   These  figures  compare
favorably  with  the $1.06/1000 liters average value for the
plants listed in Table 28.

The operating costs as a function of plant  size  have  been
plotted in Figure 14 and show that in the size range studied
costs  are roughly linear with the number of employees.  The
makeup of the production  processes  varies  somewhat,  both
with the extent of treatment and with plant size.  Processes
using  cyanide or chromate were not included where treatment
for cyanide and/or chromate was omitted.  The smaller plants
were assumed to be concerned with electroplating only  while
processes  such  as  anodizing  and electroless plating were
confined to the  largest  plant.   Even  among  the  smaller
plants there are some variations in plating processes.  Some
of  the 5-man plants included cadmium plating as a specialty
while the 10-man plant omitted cadmium but concentrated more
on tin plating.  The product mixes listed are  only  one  of
many sets that might have been chosen but reflect in general
the  amount  of   finishing  that  can be accomplished in the
various sized plants with diverse operations.  The amount of
waste water to be treated,  and the amount of waste  produced
are thus typical of the various size plants.

The  productivity  of  a  plant, measured in area processed/
hour will vary with the process mix  even though  the   number
of  employees  is  not changed.  Thus,  in Table  30 the  5-man
plants that require  only   coprecipitation   (A)  or   cyanide
                               156

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                                             TABLE  25
                                                                 TREATMENT EQUIPMENT COSTS. VALUES IN U. S. DOLLARS. 1974
5 Employees

A.












B.







C.


D.
E.


f.


a.


Item
Concrete Holding Pits
Valves. Controls, Monitor* & Recorders
Stirrers
Pumps
Tanks
Clarifies
Lagoons (Soil)
Polishing Filters
Evaporator
Ion -exchanger
Sulfonator
Chlorinalor
Subtotal A
Treatment Building
Land Cost, Urban
Rural
Land Cost, Pirs& Lagoons. Urban
Rural
Subtotal B
Urban
Rural
Total A&B
Urban
Rural
Equipment Installation
Total C&D Urban
Rural
C&D, Less Clanfier, Urban
Sludge Filter (Option)
Urban
Rural
Total E&F
Urban
Rural
A
410
2,600
1,100
3,740
2,945
12,550
100
2,600
--
--
--
--
26,045
3,990
245
50
40
10

4,275
4,050

30,320
30,095
5,210
35,530
35,305
22, 980

3,860
3,890

39,390
39, 195
B
420
4,850
1,100
4,770
3,550
12, 550
130
2.700
--
--
--
3.550
33, 620
5,910
365
75
30
10

6,305
5,995

39,925
39,615
6,725
46,650
46.340
34,100

4.590
4.620

51.240
50.960
C
550
5,080
1.100
4,845
4.930
14,900
230
2,700
--
--
3,550
--
37,885
8,160
500
100
30
10

8,690
8,270

46.575
46, 155
7,580
54,155
53.735
30,255

4,850
4,880

59.005
58,615
D
605
7.215
1.100
6,300
5,300
14,900
230
3,300
--
--
3,550
3.550
46,050
9,960
610
125
45
10

10,615
10,095

56,665
56. 145
9,210
65,875
65, 355
50,975

4,300
4.330

70,175
69, 685
A
950
2,945
1,100
4,940
2.780
19. 100
100
3,150
--
--
--
--
35,065
9,660
595
120
225
45

10,480
9,825

45.545
44.890
7,015
52,560
51,905
33,460

7,750
7.880

60, 310
59,785
10 Employees
B
945
5,080
1,100
6,390
3.700
19,000
130
3.200
--
--
—
3,550
43,095
11,760
720
145
185
40

12,665
11,945

55,760
55.040
8,620
64.380
63, 660
4,538

7.720
7,850

72,100
71,510
C
1,335
5,310
1,100
6,800
4,605
22,400
230
5.100
--
--
3,550
--
50,430
15,060
925
185
285
60

16,270
15,305

66,700
65,735
10,090
76,790
75,825
54.390

7,745
7.880

84,535
83,705
D
1,350
7,445
1,100
7,890
5,105
22,400
230
5.100
--
--
3,550
3,550
57,720
16,710
1,025
205
275
55

18,010
16,970

75,730
74,690
11,545
87,275
86.235
64, 875

7,745
7.880

95,020
94,115
A
1.545
2.945
1.100
5,650
3,895
25,400
160
5,600
• -
—
--
--
46,295
13,020
795
160
240
45

14, 025
13,225

60,320
59,520
9,260
69,580
68,780
44,180

11,380
11,510

80. 960
80,290
20 Employees
B
1.525
5,310
1.100
7.110
3.440
25,400
160
6.500
--
—
--
3.550
54.095
18.540
1.135
230
370
75

20.045
18.845

74. 140
72.940
10,820
84.960
83,760
59. 560

11.240
11.490

96.200
95.250
C
1,725
S.310
1,100
7,880
5.715
28, 000
230
6,500
--
--
3,550
--
60,010
19,050
1,170
235
300
60

20,520
19,345

80,530
79,355
12,005
92,535
91,360
64,535

12,380
12,580

104,915
103,940
D
1.740
7,445
1.100
12.340
7,200
28, 000
230
6,500
--
--
3.550
3,550
71,665
21, 180
1,300
260
310
65

22,790
21,505

94.455
93. 170
14,335
108.790
107,505
80,790

12. 380
12, 580

121. 170
120,085
A
2.490
7.786
2.200
9,300
8.355
47. 100
470
14.000
146,000
550
..
--
243,200
29,520
1.810
365
475
95

31.805
29, 980

275.005
273.180
48,640
323.645
321,820
276.545

12,930
13,220

336,575
335.040
47 Employees
B
2.535
10,610
2,200
11,610
13.955
47, 100
470
14, 000
146.000
550
	
3,550
252,580
33, 150
2,030
410
520
105

35,700
33, 665

288, 280
286,245
50,520
338, 800
336,765
291.700

12.930
13,220

351.730
349, 985
C
2,890
9,690
2,200
11,880
12.230
49, 600
600
15,600
146.000
—
3.550
..
254.240
44.370
2,720
545
765
155

47.855
45.070

302,095
299. 310
50,850
352,945
350,160
30,335

12,550
13, 050

365. 495
363,210
D
2. MS
14.485
2,200
12, 740
11,730
60.600
710
15.600
146,000
	
3.550
3,550
264,130
45,360
2.780
560
805
160

48,945
46,080

313, 07S
310, 210
52,830
365,905
363,040
315, 305

12,650
13,050

378.455
376.090
B-Cyanide oxidation plus neutralization.
C'Chromate reduction plus neutralization.
D-Cyanide oxidation chromate reduction, neutralization.

-------
                                                                          TABiiE  30
                                                                                                 ANNUAL OPERATING COSTS.  WASTE TREATMENT, U. S.  DOLLARS.  1914
Ul
00

Fr:?.






20

2-
  • I'tban u. -'os 19.706 :3.S97 :o.75i 36.513 34.S--5 4J.057 43, :52 50. >0 65.601 110.970 125 S12 122.495 142.^94 (L'iints Filter Pieal Rural lo 14$ Is. -50 19 553 2f .VI 36.3:3 34. 0:4 4: S5-1 4- ??? Sc.113 65.2S4 111' Oil r.t as 121 366 141. 1SJ O SO. IV^ahom for sludge containing 4 percent solidi (ei Equal to lnvtitrrifi.! com ) Bated on a d.ag'wt raw c-f 2 gu/IOOQ iq ft plated and a wlution COM of 2. so/gallon (11) Difference between urban and rural Is the COM of Kwage charge only (U> Credited for the com at ilodge removal. UK In conjunction with Equipment Co«t Da

  • -------
          160,000
    S-i
    >*
    
    CO
    [fl
    o
    o
    
    00
    c
    OJ
    ex
    o
          140,000
          120,000
          100,000
           80,000
           60,000
           40,000
           20,000
           O Coprecipitation only
    
    
           d Oxidation of cyanide +
    
               Coprecipitation
    
    
           A Reduction of chromate +
    
               Coprecipitation
    
    
           X Oxidation of cyanide, reduction
    
               of chromate, Coprecipitation
                              10
    20
    30
    40
    50
                                            No.  of Employees
    
    
    
                    FIGURE 14,  OPERATING COSTS  RELATED TO PLANT SIZE AND
    
                                EXTENT OF WASTE  TREATMENT
                                          159
    

    -------
    oxidation  plus  coprecipitation for treatment of wastes can
    process 75 sq m/hr, while 5-man plants that include chromium
    plating and chromating (C,D) can process 100 sq m/hr.
    
    It was concluded that costs for  a  captive  or  independent
    shop would be similar if the waste treatment plant was sized
    for    the    electroplating    operation   only.    Captive
    electroplating operations may discharge  waste  waters  into
    large  systems  that handle other plant wastes, but it would
    be difficult to estimate what volume percent of waste  water
    typically  came  from the electroplating operations and what
    portion of total waste treatment costs should  be  allocated
    to  them.   Flow  sheets  of the waste treatment plants that
    were costed are shown in Figures 14, 15, 16, and 17.
    
    Another  plant  was  modeled  to  ascertain  investment  and
    operating  costs  of  a  medium  large  plant  employing  (1)
    segregated chemical treatment  of  waste  waters  containing
    individual  metals,  and   (2)  no  discharge  of pollutants.
    Costs  for  a  waste  treatment  employing  destruction   of
    cyanide,    reduction    of    chromate    wastewaters   and
    coprecipitation of all metals were also developed as a basis
    of comparison.  Table  31   summarizes  both  investment  and
    operating  costs  of the waste treatment plants.  Investment
    and operating costs increase in the order
    
           (1)  Combined chemical treatment and
                 coprecipitation
    
           (2)  Segregated chemical treatment and
                 coprecipitation
    
           (3)  combined chemical treatment plus
                 end-of-pipe treatment to eliminate
                 discharge of  pollutants.
    
    The operating  cost   for   combined  chemical   treatment   and
    coprecipitation is equivalent, to $1.41/1000 liters,  which is
    approximately  30  percent  higher than the $1.09/1000  liter
    figure for a   similar  model  in  the  previous  discussion.
    While  the  two models are slightly different  the  difference
    is mainly due  to the  fact  that  the  two  cost  values  were
    arrived   at  by two cost analysts, each of whom  assumed what
    he  considered were  the   most  realistic  costs.    Such  a
    discrepancy  is  not  surprising and indicates the necessity
    for making analysis self-consistent.  Thus, the  results   in
    Tables  29  and  30   were  made  by one analyst  and  are set of
    cost  factors  and the  cases (1)  through  (3)  above by  another
    analyst   with  a  different,   set  of  cost   factors.    The
                                    160
    

    -------
                                                TABLE  31      INVESTMENT  AND  ANNUAL  OPERATING  COSTS  TOR  VARIOUS  TYPES  OF  WASTE
                                                                    TREATMENT  FOR  REPRESENTATIVE  AVERAGE  PLANT  (38  EMPLOYEES)(a)
    Electroplating
    Atcas Schc "j:u- re-n. -, tit to -> of the \ IIIOIK trciimcnt i> stems used arc
    m"/hr
    m
    775
    
    775
    
    
    
    
    
    775
    
    775
    
    Build lng uth.n shipped.
    i for urban and
    tnpmont. emju
    Instrument
    Equip-
    ment6) Total
    142.500 219,200
    142.500 215,100
    
    366,300 461.000
    
    
    366 300 453,700
    
    
    276.300 302.570
    
    276,300 358,610
    
    c.i Task 2. Equipment
    Annual Annual
    Deprccla- Interest
    lion**', Charge(0.
    dollars dollars
    21,900 17,540
    21,500 17,200
    
    46,100 36,880
    
    
    45,370 36,300
    
    
    36,260 29.010
    
    35,870 28,690
    
    
    LaboKg).
    dollars
    
    Maintenance Electric
    Charge(h), PowerO),
    dollars dollars
    28,000(a> 6,580 2600
    28,000(fl
    
    32,000
    
    
    32,000
    
    
    32,000
    
    32.000
    
    ) 6,450 2600
    
    13, 830 2860
    
    
    13.610 2860
    
    
    10.880 2970
    
    10,760 2970
    
    and tanks, etc. were sized to 150 percent of normal operating c
    Water and
    ChflrgesO).
    dollars
    1040
    520
    
    1040
    
    
    520
    
    
    1040
    
    520
    
    
    UsedW.
    dollars
    26.300
    26,300
    
    29. 820
    
    
    29,820
    
    
    28, 100
    
    28, 100
    
    apactty. Cons are based
    Osmosis Water and R.O. Cor.c. Dried
    (R.O.) Sewer Sav- E^aporatoi Salt 10:2.
    Disposal^). rWn), R.O.O). CoW™, r.oafb. r-y^.
    dollars dollars dollars dollars dollars da.ian
    6460 — -- -- -- 11- .4^,
    6460 -- — -- — lJ*.0*i
    
    4400 15.700 9920 25,44-3 1670 15a. Z-j
    
    
    4400 15,700 4960 25,440 16"0 2:2.73^
    
    
    7400 -- — — — 147. c£3
    
    7400 -- -- -- - 144.311
    
    on an 8-hour day, S days/ week (I.e. , 2000 hi/year).
    , plating and rinsing sequences, bath compositions, etc.
    rural locations, respectively.
    u-cnne, and other items associated with setting up a wasti
    ips, pH and ORP monitor/
    : treatment plant were arri
    ved at by i
    controllers, electric mixers, and other items which were sized for the overall plant
    jsing a factor of 1.40 times the purchased
    design). A factor of 1. 15 v
    cost of the
    main equipment items (e.g.. tanks, reaction vessels.
    /as used on the R.O. unit and the R.O. concentrate evaporator, since the* ufiia
    ,;!  TV i. a-r-? tr. a—-vn UVi charge u>cd \. as ?3.00/hr. a 1-3/4 man/day figure was used for Phase 1 and a 2 man/day figure was used for Phases IA and II.
    ,b*  \ r-a.-tt -j-ve c^-arce of 3 percent of the  total m\e!tment was employed.
    (i*  A pov,er cost oi ^ ^15 K*.hr was used. A \alue of UO gal water treated per Kwhr was used for Phase I calculations, this basic value was adjusted lower for the Increased processing uied in Phases IA and II.
    ,l\  T>e co«t oi\atcr vaj taken as JO.25 '1000 5al for both urban and rural plants. A sewer charge of $0.25 gal/1000 gal of water used in the WT operations was applied.  These same costs were used to determine the urtngi achieved by the ute of the R.O. Ireatmem.
    
    -------
                                                   High-end low-level control
                                                           High-and low-level control
                       ,  Stream
    FIGURE  15-TYPICAL PLANT  OPERATION
                 CO PRECIPITATION ONLY
    - CHEMICAL TREATMENT  (A);
                                            162
    

    -------
                                        Acid-alkali
                                        holding and
                                        mixing
    Cyanide
    holding and
    mixing
                                      Neutralization
                                         and
                                      precipitation
     Cyanide
     oxidation
           Filter)	
                         Stream
    FIGURE 16 .TYPICAL PLANT OPERATION -  CHEMICAL TRFATMEI-- (B)-
                CYANIDE OXIDATION AND COPRECIPITATION
                                          163
    

    -------
                                                       H and L
                                             Acid-alkali
                                             holding and
                                             mix'ng
                                        H and L
                              Chromium
                              holding and
                              mixing
           Plating
           Non-CN/Non-Cr
                                                                              Flocculant
    o o
                     Overflow
                                          H and L
                                           Filter
                             ir
    
                         To stream
                                                        Pump       pump
    Filter
     Backwash
    FIGURE  17. TYPICAL PLANT OPERATION -  CHEMICAL  TREATMENT (C)-
                  CHROMIUM REDUCTION  AND CO PRECIPITATION
                                                164
    

    -------
                                                                              H and L
                      Neutralization
                          and
                      precipitation
     Filter    Pump
                H and L1
      O,
           I	
    Lagoon
                          Circ.'
                          Pump
                                 *—O
                                                     NaOH
                                     pH
                                               CH
                                               S02
                            Pump
                                        Sump
                       Settling
                                      Pump
                               Flocculant
     Overflow
    H and L
                   Filter
                                Pump
                                PumpQ Q Pump
           Filter
                            Backwash
       To stream
    
    
    FIGURE 18 .TYPICAL PLANT OPERATION - CHEMICAL TREATMENT (D);
    
                 CYANIDE OXIDATION, CHROMIUM REDUCTION, AND
                 CO PRECIPITATION
    
                                          165
    

    -------
     difference  is actually much  smaller  than  that  of  actual
     costs  reported in Table  28.
    
     The  use  of  a  system  to  eliminate  pollutant  discharge
     requires  approximately twice the  investment  and  operating
     cost as a system for combined chemical treatment.  The costs
     can  be   reduced  in  some situations by in-process recovery
     systems where the savings in chemicals more than  compensate
     for the costs of operating the recovery system.  Evaporative
     recovery  systems  were  not economical to use in the plants
     assumed since the value, bath concentration, and dragout  of
     chemicals  were  not  sufficient  to  make  their in-process
     recovery  worthwhile.  The costs of installing more  counter-
     current   rinse  tanks, evaporative equipment, and steam more
     than offset the savings  in chemicals.
    
     In-process  reverse osmosis systems may have lower  operating
     costs   than   evaporative  systems,  but  are  still  in  a
     demonstration stage for  baths other  than  nickel.   Use  of
     reverse   osmosis  systems  on  the nickel lines in the plant
     model would not be expected to reduce overall  in  operating
     costs by  more than 5 percent.
    
     Figure  19  shows the operations in the plant and a schematic
     diagram of  a segregated  waste treatment system.   Figure  20
     shows   a   coprecipitation   system   and   Figure  21  the
     modifications made at the end of the coprecipitation  system
     with a reverse osmosis unit and salt evaporator to eliminate
     the discharge of pollutants.
    
     Preliminary  calculations  indicated that use of evaporators
     in-process  and at the  end-of-pipe  to  eliminate  pollution
     would  be more expensive than use of reverse osmosis at end-
     of-pipe for the particular electroplating lines  considered.
     With  the   installation  of  a  reverse  osmosis  system the
     neutralizing agent was sodium hydroxide rather than the lime
     used with the coprecipitation and  segregated  precipitation
     systems.    Lime was used to precipitate phosphate as well as
     metals, but precipitation products with lime are  likely  to
     foul  the reverse osmosis membranes.  These membranes remove
     phosphate directly and lime is not needed.
    
    The cost of  a  minimum  batch  treatment  system  was  also
     estimated.   The layout is shown in the schematic diagram of
     Figure 22.  The system was sized  to  handle  4500  1/hr  of
    waste  water, which is less than produced by the 5-man plant
     discussed above.   For calculating operating costs an  8-hour
     day and 5-day week were assumed.
                                  166
    

    -------
                                       SEGREGATED STREAM TREATMENT
    Line 1
    (Aut. RavM
    CuCN 180 gph
    Ni 270 cph Combined CuCN
    Ct 10-, , |, * 18° * 55 = 235 SP*1 *"
    A A 1730 cph
    
    Line 1
    Cu- \'i-Cr
    Man Ra«k
    
    
    <~r HO
    CN
    Cu PPP.
    
    NiNeut
    PPT
    
    
    it
    
    
    
    
    
    * A 435
    
    Lii'o J
    Aut Raik
    C rumaiL
    
    
    Barrel
    i~';;o Mate
    Line 5
    Man. CaJmm •
    CX Line
    &
    
    Manual Hard Cr
    1 	 i^T- 	 1
    Vanual Rark
    An Lid Line
    
    Line 3
    
    
    Lire y
    Elc.tMc-
    /.n(( M_, 3f,s ,-ph romhitud Cr Plat
    fc 495+ 140 +75 = 710 gph """
    Z.IIK i L hroinaie 110 ppli
    * A 10oO gpli
    Combined Zn{CN)2
    ZHR i rhromate llu sjph
    A A lu50 ^Ptl r*tr\i\
    Cd(CN) 115gph "^
    Cliruiiiiuni
    Reduction
    
    CN Desr,
    &
    Zn PPT
    Cr Ntut
    PPT
    	 »- Underflow to Centrifuge #1
    	 •-• Effluent to Stream
    	 ^ Underflow to Centrifuge /I
    	 	 	 -—— 	 »»- Effluent to Stream or Sewer
    /rTentMX
    ~\.M) *" °"' S'Udl?ClOU?00riSl0ra?e
    1
    
    
    
    
    CN Dest
    &.
    Cd PPT
    
    	 »- Clanfie
    
    i. d-( hr.uiiaie 40 i^pii
    A -A 4(KJj;ph Comb. Chtomate Streams
    110 + 110 + 40 = 260 gph
    i f 7S cph
    Acid/AIk Streams 7060 gph
    1730 + 995 + 1050 +1050
    flr. Pip - Al CfiO cph
    An .id - Al 130 uph
    M Ac,t. - Al 3.5 cph ^ Combined Al Anod.
    Zn Phosp. 130 gph
    Clirom
    Iteduction
    A/A Neittraltza
    and Precipnat
    NCUC&
    
    
    Elect. Ni 30 gph
    A A 70i cph
    Elect Ni 3i) gph
    A 'A 375 gph
    Raise pU to
    13 0 to
    Destroy
    Complex
    
    Cr, Zn, &
    & PPT
    tion
    r
    i . — •-=.
    — »- Clanfier 	 1
    
    
    
    C
    t
    i 	 •
    . /^""^
    ^i '"H1- 1 	 ^ idOJ/o Sludge to Lagoon Storage
    	 ^ UnderQcw to Centrifuge /I
    | 	 — ' 	 ^ Effluent to Stream or Sewer
    
    arificr — — ~ 	 ^- Underflow to Centrtfugt /2
    /f entri-\ 20^0 SlLtdge
    *^ fuge I 	 ^ To Lagoon Storage and
    X/4/ Later Haul Away
    /TemriN
    \^ / 3 y To Lag00" Storage
    FIGURE  19.  PHASE I,  IA, AND II MASTER FLOW PATTERN
    

    -------
                                                  Clj
                                                         NaOH
    00
    Cone.
    4(5 mg/1 CM
    Combined Cjranide Streams 108 /, Ca
    Cu » Zn •, Cd 288 "g/1 z"
    235* 710 f 115 = 1060 gph S4 mg/1 Cd
    HoSO«-
    Combined Cr «• Chromate Stream
    Or riatinc- 4;>S . 140 » 75 - 710 gph
    Chroma! ing: 110 + 110 * 40 = 2SO gph
    Total s^O cph
    L1K-.C —
    Combined Anodizing £ Zn Phocphating
    •:«o » :so * 345 = S35 ,:pii
    Zn rhoip. * 130 gph
    NaOH — •.
    Elect. Xi 150 gph
    Nl rutirK ,t Acid 'Alk Streami
    350 » 7060 gph
    T T
    Cyanide
    Denuctlon
    ^^
    i r802 ^-^
    Chromium
    
    1
    NeutraUuilon
    and
    Precipitation
    of Phosphatei
    
    Destruction of
    pH 13
    
    HjS02 Lime. Ca(OH)2
    I 1
    ^-^
    
    
    
    
    
    
    
    ,—
    
    Combined
    Neutralization
    and
    necipiuiion
    
    
    
    
    
    or Sewer
    -/ Clarlfler \
    2H Solid!
    Underflows
    1 ( Centrifuge I «» 2«; slu
    V J To Ugc
    N»«_^' for Late
    
             Tot « "410 gph
                            FIGURE 20.  COMBINED CHEMICKL TREATMENT AND NEUTRALIZATION-PRECIPITATION
    

    -------
    (Ti
                 Combined Cyanide Streams
                     Cu + Zn + Cd
    
                 235 + 710 + 115 = 1060 gph
                                                              HjSC
                 Combined Cr Plating and Chromating Streams
    
                 Ct Plating: 495 + 140 t 75 « 110 gph
                 Chromating- 110 + 110 + 40 = 260 gph
                           Total 910 gph
                  Combined Anodizing aad Zn Phosphating Stream!
    
                  Anodizing- 260 » 230 + 345-835 gph
                  7-n Phosphating 130 gph
                     Total 965 gph
                  Electroleu Ni   150 gph
                  Nl Plating & Combined Acld/Alk Streams
    
                  Combined Acid 'Alk   7060 gph
                                                                                                                                                             Dried Salti
                                                                                                                                                             lot Haul-
                                                                                                                                                            Away Dupoial
        udge
    To LAgoon Storage
    for Haul Away Diapoul
                  Ni Plating  350 gph
                                       Total 1410 gph
                            FIGURE   21   COMBINED  CHEMICAL TREATMENT  AND PRECIPITATION FOLLOWED BY  END-OF-LINE
                                             REVERSE OSMOSIS  TREATMENT  FOR  ZERO  LIQUID  EFFLUENT  DISCHARGE
    

    -------
    Acid Alkaline
    1000 gph
    
    
    
    
    Cyanide
    100 gph
    
    
    
    
    
    
    —CftX'Qroate
    100 gph
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    <
    Q,
    
    
    
    
    
    ,
    ^
    
    
    
    
    
    
    
    
    
    k
    r
    
    
    
    
    f" ' '
    
    *
    j
    
    
    
    
    
    
    800g
    
    
    
    800g
    
    
    
    800g
    
    
    
    o r\ r\~
    duug
    
    
    
    
    — ^5—
    V3*
    
    
    /Qv
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    Neutralization
    
    i^.UUUy
    
    m-^^... n i- <^ Effluent
    vy Jlarifier x>
    
    
    
    Slungp?
    
    
    
    
    
    
    FIGURE 22.  BATCH TREATMENT SYSTEM FOR SMALL PLANT
    

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     Small  Platers
    
     Costs  have  been estimated  for the  1-4 man  shop and 5-9 man
     shop and may be found  with accompanying assumptions  in  the
     following tables:
    
     Sizing Assumptions
    
      .  1-4 employee shop (3  employees)
      .  30  sq m plated per  hour
      .  80  1/sq m per hour
      .  1/4 of the  flow  is  cyanide  bearing  (and can  be
         segregated)
      .  The cyanide concentration is 20 ppm
    
        The concentrations  in  the rest of the flow are equivalent
        to  100 ppm  of FS+++
    
     Engineering Assumptions
    
      .  Complete manual  operation utilizing minimal  equipment
      .  Store 1 day of cyanide containing waste and  treat overnight
      .  Equalize flow in a  tank corresponding to  1/2 of the
        daily output.  Operate in backmix with adjustment every
        two hours.
     . All  adjustment from carboys or drums.
    
     Manual_Handling pf  chemicals Verification
    
         Cyanide   Total waste flow        2400 1/hr
                   Cyanide flow            600 1/hr
                   Total cyanide waste     4800 I/day
                   Total cyanide in waste   98 gm per day
    
                   Chlorine requirement    approximately 700 gm per
                                            day or  1.5 Ib
    
                   Using hypochlorite (1 Ib C12   1 gal hypochlorite)
                                            1.5 gallons per day.
    
                   Using caustic           1 lb/1  Ib of chlorine - say,
                                            1.5 Ibs/day
    
    Neutralization  (Assume that the caustic from cyanide treatment
                     is used in the first  1/2 day)
    
         Total caustic required   -   about 2 gm  per gm of iron (120/56)
              1/2 day flow      9600 1          960 gm of iron
         Caustic  required  -          2800 gm/or  4.5 Ib.
         Additional  -       4.5-1.5=3 Ibs.
         Rest  of  day  -       4.5 Ibs.
         Total  per  day    -           7.5 Ibs
    
         O.K.  to  add by  hand  (drum of  caustic - approximately 400 Ibs)
         O.K.  to  use  a small bucket (8 gals,  approximately or 80 Ibs)
    
                                     171
    

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    Residence time - U hours (nominal or actual)  for equalization
    Egujpment_List
         Equalization tank - 2500 gals.
         Agitator - 5 HP
         Chlorination tanks - 2 x 800 gals.
         2 Agitators - 1 HP
         1 Transfer pump
         High level alarm - 3
         Valves - 5
         Other piping and supplies
    
         Installation - 25%
                                                $8500
         Instrument
              pH meter
              colorimeter
    400
    200           	600
           Total  $9100
    Area required - 400-500 square feet  (assumed available)
    
    Assume that there is room for equipment, e.g. a  2500 gal. tank
    of normal configuration is 6.51 in diameter and  10* in
    height  (without legs) .
    
    Sizin3_Assumptions
    
       5-9 employee shop  (7 employees)
       70 sq m plated per hour
       80 1/sq m      5600 1/hr of flow
       1/4 flow is cyanide bearing  (and  can  be segregated)
       Cyanide concentration = 20 ppm
       The concentrations in rest of  waste flow are  equivalent
       to 100 ppm FS+-H-
    
    Engineering Assumptions
    
      . Cyanide flow - 1400 1/hr - say,  350 gals/hr.
      . Assume that a hand operation once a day is used for  cyanide
        (Automatic continuous unit would  cost about  $18,000-22,000).
      . Equalize daily flow in a  1/2 day  tank.
      . Check  for hand addition - or cheapest equivalent.
    
    Hajjdling_Of_Chemicals
    
         Cyanide  . Cyanide total -  11,200 I/day    2800 gals.  (3000)
                  . Total  cyanide in wash -  22U gm/day
                  . Chlorine  required  -  1500  gm/day say 3.5  Ibs.
                  . Hypochlorite  -  1 gal/lb of  chlorine  3.5 gallons
                                       172
    

    -------
                   (can be added out of a plastic lined 55 gallon
                    drum with a hand pump)
                   Caustic -                             3.5 Ibs.
                   Out of a 55 gallon drum  (  500 Ib) with a
                   scoop, (a big scoop is about 5 Ib)
    
         2g_Adjust  2 gm per gm of iron
                    1/2 day flow (total)     22,400 1.    (say 6000 gals)
                       Iron                   2,210 gm
                       Caustic                4,500 gm           10 Ibs.
                       2 to 3 scoops.
    
    Manual addition from a drum appears feasible.
    
         Material handling equipment - 1 chlorine resistant
         hand pump - say $200
    
    Equipment List
    
         1 Equalization tank - carbon steel   6000 gals.    $ 4,100
         2 Cyanide treat tanks - carbon steel, epoxy lined*   7,200
           (3000 gal)
         3 Agitators (1) 10 HP, (2) 5 HP  (3500) (2 x  1000)     5,500
         Transfer pump                                           300
         High level alarms                                       400
         Valves  (5)                                              500
         Other piping and supplies                          _,m-.-^300
                                                             18,300
         Installation - 25%                                 	4.600
                                               Total        $22,900
         Instruments
              Hand pump                                          200
              pH meter                                           400
              Colorimeter                                   	29.0
                                                            $23,700
    
    *Add 20% for epoxy lining.
    
         If a 2 hour equalization is required
           use a 3000 gal tank + 5 HP agitator  (3000 +  1000)  4,000
           instead of 4100 + 3500  (7600)
           thus, 18300 - 3600                                14,700
                                                              3.700
                                                             18,400
                                                 Save         4,500
                                                 Total       19^000
    
    The total capital investment and operating and maintenance costs
    for both size plants are as follows:
                                     173
    

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      No. of    Capital Investment ($1000)     Annual O&M Costs ($1000)
    employees     80 1/sq m    160 1/sq m       80 1/sq m   160 1/sq m
                 min    max    miin   max       min    max   min   max
      1-1        9.1    13.7   13.7  20.5      3.9    6.5   3.9   6.5
      5-9       23.7    35.6   35.6  53.3      4.3    7.1   4.3   7.1
    
    New	Source ^Performance_StandardsjNSPS^.  New sources that
    are  required  to  meet   the   recommended   standards   of
    performance  have  the opportunity of designing and building
    plants that reduce water flow.  Such systems as counterflow,
    spray, and fog rinses, interlocks to provide water flow only
    during  processing  sequences,  drip  tanks,  etc.,  can  be
    provided.  The capital investment for installing an extra 31
    x  31  tank  in  each  rinsing sequence of a plating line to
    reduce further the water use in counterflow  rinsing  is  of
    the  order of $3,000.   The plant modeled in Figure 18 has 22
    rinses so adding one more tank for each rinse would increase
    capital investment $81,000  for  a  total  of  $300,200  for
    combined  chemical  treatment  and precipitation in an urban
    plant.  It is probable that water use  can  be  reduced  100
    percent  by  installing  only half this number of tanks at a
    cost of $40,000 or an increase in capital investment  of  18
    percent  over  a  plant meeting BPCTCA standards.  Operating
    costs would increase $7200/yr minus a  credit  of  $520  for
    water  and  sewer  charges  or  $6680/yr.   The  increase in
    operating cost is 6 percent as compared to those for a plant
    meeting BPCTCA standards.
    
    No Discharge of Pollutants
    
    The elimination  of  liquid  discharge  from  electroplating
    processes has not been demonstrated with present technology.
    Anticipating   that   future   development  will  make  this
    elimination possible,   it  is  desirable  to  have  a  rough
    estimate  of  the  cost  impact of doing this.  Technically,
    evaporative recovery,  reverse osmosis,  and ion exchange  can
    concentrate  wastes  after  which  the  concentrate  can  be
    evaporated essentially to dryness.  Purified  water  can  be
    returned  to  process.   Approximate cost analysis have been
    made for a medium large plant 240 sq m (2600 sq ft) per hour
    assuming use of 80 liters/sq m of  water.   The  effects  of
    closing  the  liquid  loop without a purge on the buildup of
    impurities are not known and the cost  of  solving  problems
    connected with impurity buildup will depend greatly upon how
    much  impurity must be removed, the development of efficient
    systems for their removal, and how many  of  the  components
    that are recovered can be recycled rather than discarded.
    
    To  determine  the cost effectiveness of various control and
    treatment alternatives much of the data developed for  Plant
                                    174
    

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    33-1  in  Phase  I  was  used.  For those examples involving
    evaporative recovery, an additional investment  of  $150,000
    was  allowed for a unit to evaporate concentrate to dryness.
    Results of the  calculations  are  shown  in  Table  32.   A
    finishing  cost of $2.70/sq m ($0.25/sq ft)  is equivalent to
    $644/hr, and all of the projected costs for waste  treatment
    are  less  than  10  percent of this figure.  Of course, the
    $2.70/sq m figure  is  too  high  for  some  processes,  but
    provides  a  basis for at least a rough estimate of the cost
    impact of waste treatment.
    
    Nonwater. Quality Aspects
    
    Energy Requirements
    
    Introduction.  Energy requirements  will  be  discussed  for
    chemical  treatment,  evaporative recovery, ionexchange, and
    reverse osmosis.
    
    Chemical,, Treatment.   Energy  requirements   for   chemical
    treatment~are low,"the main item being electrical energy for
    pumps,  mixers,  and  control instruments.  Electrical costs
    have been tabulated for several plants in  Table  33.   Data
    for  Plants 33-1 through 33-6 were obtained from the Phase I
    study.  Results indicate that approximately 5 percent of the
    waste treatment cost is for electric power.
    
    It is estimated in the Phase I study that electrical  energy
    for  treating  2.271  x  10*  liters  per  hour by a reverse
    osmosis unit for 4000 hours per year would cost $6,400.  The
    electrical energy cost  is  therefore  7.045  x  10-s.   The
    liters  per  year processed by all plants listed in Table 61
    add up to 3.964 x 10« liters and the cost of electricity for
    processing this water by reverse osmosis is  $279,200.   The
    total  electrical cost for chemical treatment for the plants
    listed in Table 31 is $75,330.  These figures can be used to
    roughly  estimate  the   increases   in   electrical   power
    requirements  in  going to a system with no liquid effluent.
    For best practical control  technology  currently  available
    the  electrical  cost  would  be essentially that of current
    estimates or $75,330.  For  the  best  available  technology
    economically   achievable   the   combination   of  chemical
    treatment  and  reverse  osmosis  plus  evaporation  of  the
    concentrate   (that  would  require little electrical energy)
    the electrical  cost  would  be  $75,330  plus  $279,200  or
    $354,530.   The  ratio  of $354,530/75,330 is 4.70.  On this
    basis going to a system without discharge of liquid effluent
    will increase the use and cost of electrical energy 5-fold.
                                  175
    

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                     TABLE 32   COST EFFECTIVENESS OF
                                CONTROL ALTERNATIVES
                                (247 Sq M/Hr)
      Type of Control
                                  Water      Operating
    Investment     Operating     Treated     Cost per
       Cost        Cost/Year       1/Hr      100 Sq M
    Plant 33-1
      Rinse System -          $264,274
      Chemical treatment
    
      Three countercurrent     330,000
      rinses - chemical
      treatment
    
      Single stage evapor-     890,000
      ators (21 units)
      Dry evaporator
    
      Five single stage        400,000
      evaporative units
      and one vapor com-
      pression unit - dry
      evaporator
    
      Chemical treatment       560,000
      plus reverse osmosis
      Sludge drier and dry
      evaporator for
      concentrate
                   $112,361
    
    
                    121,387
    
    
    
                    327,895
    
    
    
                    109,913
                    161,328
    25,210
     9,766
    $17.30
     18.68
                 50.47
                 16.92
                 24.83
                                       176
    

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    TABLE 33   COST OF POWER RELATIVE TO TOTAL  OPERATING
               COST FOR CHEMICAL TREATMENT
    Plant
    No.
    33-1
    11-8
    36-1
    20-14
    20-17
    3-4
    33-3
    33-6
    33-22
    20-20
    20-22
    33-24
    36-12
    33-2
    33-4
    8-5
    6-35
    30-19
    
    
    Processes
    Plating Cu, Ni, Cr, Zn
    Plating Cu, Ni, Cr, Zn
    Plating Cu, Ni, Cr, Zn
    Plating Cu, Ni, Cr, Zn
    Plating Cu, Ni, Cr, Zn
    Plating Cu, Ni, Cr, Zn
    Plating Cu, Ni, Cr, Zn
    Plating Cu, Ni, Cr, Zn
    Anodizing
    Anodizing
    Anodizing
    Plating Common Metals
    Plating Precious Metals
    Plating Precious Metals
    Plating Precious Metals
    Plating Precious Metals
    Chemical Milling
    Chemical Milling
    
    
    Electric
    Cost/Year
    $ 4,100
    668
    5,220
    6,000
    8,940
    600
    240
    1,460
    1,948
    4,763
    12,623
    1,212
    1,894
    1,082
    120
    16,239
    3,897
    4,330
    x - 4,185
    a = 4,454
    Waste
    Treatment
    Operating
    Cost/Year
    $112,361
    391,406
    221,009
    93,240
    798,840
    4,064
    18,019
    77,460
    51,515
    83,481
    113,370
    80,430
    72,809
    14,968
    18,205
    115,995
    83,758
    168,312
    x = 139,957
    a - 187,688
    Electric
    Cost x
    100/Waste
    Treatment
    Cost
    $ 3.65
    0.17
    2.36
    6.44
    1.12
    14.76
    1.33
    1.88
    3.78
    5.71
    11.13
    1.51
    2.60
    7.23
    0.66
    14.00
    4.65
    2.57
    x = 4.75
    a = 4.44
                             177
    

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    Evaporative Recovery.  From the Phase I report the  cost  of
    steam  for  operating  a  300 gph single-stage evaporator is
    approximately  $2100/yr   corresponding   to   approximately
    1,900,000   Ib  of  steam.   The  single-effect  evaporators
    require  considerable  energy.   This  requirement  can   be
    diminished  by  use  of  multiple stage or vapor-compression
    evaporators.
    
    Ion Exchange.   The  few  pumps  required  for  ion-exchange
    systems should consume very little power.
    
    Reverse Osmosis.  The energy requirement for reverse osmosis
    systems  is  the electricity for operating the high pressure
    across the membrane and for operating low pressure  transfer
    pumps.   The  estimate  is  $6400/yr for a 6000 gph facility
    operating 4000 hours/yr.
    
    Impact of Power Requirements for Waste
    
    Treatment.  Domestic production of electrical energy in 1971
    was  1.717  x  10*2  kwh.   For  the  plating  industry  the
    electrical  energy requirement is estimated to be 9.75 x 108
    kwh.  The electroplating industry as a whole is estimated to
    consume no more than twice this value, which would be  1.950
    x  10» kwh.  The percentage of annual power that is used for
    electroplating operations should be no more than:
    
    1.950 x 10»i/1.717 x 10»2 = 0.114 percent.
    
    Power for pumps, lights, fans,  etc.,  and  waste  treatment
    should not more than double this figure to 0.228 percent.
    
    Cost of Recovery of Metal Values from Sludge
    
    Reference (32)  is a report on the feasibility of recoverying
    metal  values  from sludge by digesting the sludge with acid
    to dissolve it followed by electrolysis  and  neutralization
    procedures to recover metal values.   The case considered was
    a  sludge containing primarily copper, nickel, chromium, and
    zinc values.  A cost estimate was included for a small plant
    that would treat 45 kg of dry sludge during a 12 hour day to
    yield 2.27 kg of copper, 0.09 kg of nickel,  and 4.54  kg  of
    chromium.    However,  the  chromium was obtained as an oxide
    mixed with some iron.   The investment for a small plant  was
    estimated  to  be  $15,130.    Operating  cost  per  day  was
    estimated to be $85.30.   This did  not  include  a  cost  of
    capital,   which  if  assumed  to  be  eight  percent  of the
    investment per year, would raise the daily operating cost to
    $91.35.   The total weight of metal recovered per day is 6.90
    kg so that the cost is estimated to be $13.23 kg.  The  cost
                                  178
    

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    is obviously very high compared to market prices so that the
    small  operation  would  be far from economic.  Undoubtedly,
    the  cost  of  processing  would  be  less  with  a   larger
    installation,   but   if   more   than   one  electroplating
    installation were served there would be an  additional  cost
    for transporting sludge to the recovery operation.
                                    179
    

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                             SECTION IX
    
           BEST PRACTICABLE CONTROL TECHNOLOGY CURRENTLY
               AVAILABLEl GUIDELINEST^AND LIMITATIONS
    
    Introduction
    
    The  effluent  limitations which must be achieved by July 1,
    1977, are  to  specify  the  degree  of  effluent  reduction
    attainable  through  the application of the best practicable
    control technology currently  available.   Best  practicable
    control  technology  currently  available is generally based
    upon the average of the best existing performance by  plants
    of  various  sizes,  ages,  and  unit  processes  within the
    industrial category and/or subcategory.
    
    Consideration must also be given to:
    
         (a)  the total cost of application of technology
              in relation to the effluent reduction benefits
              to be achieved from such application
    
         (b)  the size and age of equipment and facilities
              involved
    
         (c)  the processes employed
    
         (d)  the engineering aspects of the application of
              various types of control techniques
    
         (e)  process changes
    
         (f)  nonwater  quality environmental impact
              (including energy requirements).
    
    The best practicable control technology currently  available
    emphasizes   treatment   facilities   at   the   end   of  a
    manufacturing process but includes the control  technologies
    within  the process itself when the latter are considered to
    be normal practice within an industry.
    
    A further  consideration  is  the  degree  of  economic  and
    engineering  reliability  which  must be established for the
    technology to be "currently  available".   As  a  result  of
    demonstration  projects, pilot plants and general use, there
    must exist a high degree of confidence  in  the  engineering
    and economic practicability of the technology at the time of
    commencement  of construction or installation of the control
    facilities.
                                  181
    

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    Industry_Category and Subcateqgry Covered
    
    The pertinent  industrial  category  is  the  electroplating
    category  which  is  part  of  the metal finishing industry.
    This category includes plants using electroplating processes
    as defined by SIC 3471 (1972) and includes the  pretreatment
    and  posttreatment  steps associated with the electroplating
    processes.
    
    The identification of best  practicable  control  technology
    currently  available  and  recommended  effluent limitations
    presented  in  this  section  cover  the  subcategories   of
    electroplating   of  common  metals  and  electroplating  of
    precious  metals.   Guidelines  for  the  electroplating  of
    copper,  nickel, chromium and zinc were developed in another
    effort and the results may  be  found  in  the  "Development
    Document  for Effluent Limitations Guidelines and New Source
    Performance Standards for the copper. Nickel, Chromium,  and
    Zinc  Segment  of  the Electroplating Point Source Category"
    March 1974.  Guidelines  for  the  remainder  of  the  metal
    finishing industry will be developed in a similar document.
    
    
    Identificatign^of_Best_Practicable_Control
    Technology^Currently Available
    
    The  best practicable control technology currently available
    for the electroplating of common and precious metals is  the
    use  of  chemical methods of treatment of waste water at the
    end of the process combined  with  the  best  practical  in-
    process  control  technology  to  conserve  rinse  water and
    reduce the amount of treated waste water discharged.
    
    Chemical  treatment   methods   are   exemplified   by   the
    segregation  of  the  acid-alkali stream, cyanide stream and
    chromium stream.  Cyanide  is  destroyed  by  oxidation  and
    hexavalent chrominum is reduced to the trivalent state.  The
    waste  streams  are  then  combined  and  there  follows pH.
    neutralization and coprecipitation of metals  as  hydroxides
    or hydrated oxides with settling and clarification to remove
    suspended  solids  prior  to  discharge or prior to dilution
    with other nonelectroplating process water before discharge.
    However, the above technology cannot achieve  zero  discharge
    of  metals  because  of finite solubility of  the metals.   In
    addition, it is  not  practicable  to  achieve  100  percent
    clarification and some small amount of metal  is contained  in
    the suspended solids.  By optimum choice of pH and efficient
    clarification  it  is  possible to achieve a  significant re-
    duction in the metal pollutional load.
                                  182
    

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    Although coprecipitation of metals as hydroxides or hydrated
    oxides  is  most  widely  practiced  in  the  electroplating
    industry, much greater reduction could be achieved by stream
    segregation  and  sulfide precipitation.  However, there are
    greater  problems  in  the  disposal   of   sludge   sulfide
    precipitation.  Metallic sulfides are much less soluble than
    hydroxides and offer a far greater level of removal.
    
    Best practicable control technology currently available also
    includes water conservation through rinsing.  A water use of
    160  1/m 2/operation (H gal/m2/operation) has been estimated
    as that achievable by the industry.  This  figure  precludes
    the  use  of countercurrent or series rinses.  Exclusive use
    of single stage rinsing will not meet this  water  use.   It
    has  been  calculated  that  for 186 sg m/hr (2000 sq ft/hr)
    proudction  the  rinse  water  need  for   various   rinsing
    techniques are:
    
        1 - single rinse 1/hr 499,620  (132,000 gal/hr)
        2 - tank countercurrent 2800 1/hr (1UO gal/hr)
        3 - tank countercurrent 477 1/hr (126 gal/hr)
        H - tank countercurrent 201 1/hr (53 gal/hr)
        5 - tank countercurrent 121 1/hr (32 gal/hr)
    
    This corresponds to a water use of:
    
        1 - single rinse 2686 l/m2  (66 gal/sq ft)
        2 - tank countercurrent 15 l/m2  (.37 gal/sq ft)
        3 - tank countercurrent 2.56 l/m2 (.06 gal/sq ft)
        U - tank countercurrent 1.2 l/m2 (.026 ga/sq ft)
        5 - tank countercurrent .65 l/m2 (.016 gal/sq ft)
    
    A  3     stage  series rinse consumes approximately the same
    quantity of water as a 2 - stage countercurrent.
    
    The  160  Im2   (U  gal/sq  ft)  takes   into   account   the
    contributions  made  by  the  pretreatment steps of alkaline
    cleaning and acid pickling and allows  some  use  of  single
    rinses.
    Good management techniques considered normal practice in the
    industry are:
    
           (1)  Manufacturing process controls to minimize
               dragout from concentrated solutions such as
    
                (a)  proper racking of parts  for easy
                    drainage
                                 183
    

    -------
               (b)   slow withdrawal of parts from the
                    solution
    
               (c)   adequate drip time or dwell time
                    over the tank
    
               (d)   use of drip collection devices.
    
          (2)   Effective use of water to reduce the
               volume of effluents such as
    
               (a)   use of rinse water for makeup of
                    evaporation losses from solutions
    
               (b)   use of cooling water for noncritical
                    rinses after cleaning
    
               (c)   use of treated waste water for
                    preparing solutions for waste-
                    treatment chemicals.
    
          (3)   Recovery and/or reuse of waste water
               constituents such as
    
               (a)   use of reclaim tanks after metal
                    finishing operations to recover
                    concentrated solutions for return
                    to the plating tank to make up
                    evaporation losses
    
               (b)   reduction in waste water volume by the
                    use of at least two series flow rinse
                    tanks after each finishing operation
                    with return of as much rinse water as
                    possible to the finishing tank.
    
    Rationale rfor Selecting the Best Practicable
    Control_Technoloqy Currently Available
    
    Identification of Best Waste Treatment Facilities
    
    There are approximately 20,000 facilities for electroplating
    and  metal finishing in the United States and identification
    of the best plants within the short  period  of  this  study
    required  a  rational  screening  and approach.  The initial
    effort was directed toward identifying those companies  that
    had  well engineered and operated electroplating process and
    waste treatment methods.  Such companies were identified  on
    the  basis  of  personal  knowledge, and referrals by people
    well   acquainted   with   the   industry    (EPA    regional
                                184
    

    -------
    representatives,  state pollution control authorities, trade
    associations,  equipment  suppliers,  consultants) .     Three
    hundred nine companies were identified based on referrals by
    cognizant  people associated with the industry (EPA. regional
    representatives, state pollution control authorities,  trade
    associations,  equipment  suppliers)  and  review  of permit
    applications  were  distributed  geographically.    About  90
    percent of the companies were in the three principal regions
    expected  to  have  high  concentrations  of  electroplating
    industry: 38  percent  in  the  Northeast  (principally  EPA
    Regions  I,  II  and  III);  28  percent in the Midwest  (EPA
    Region V) ; 25 percent in the Southeast  (Region IV).
    
    Of these leads, the 129  companies  initially  contacted  by
    telephone  were  primarily  in  the principal electroplating
    regions.  The telephone contacts were  made  to  verify  the
    existence  of  adequate  waste  treatment facilities and the
    type of plating operations pertinent to Phase I.   Sufficient
    information was obtained to characterize the facility and if
    pertinent to the scope of coverage desired operational  data
    were  obtained.  From the questionnaires returned,  seventeen
    plants  were   identified   which   are   engaged   in   the
    electroplating  of  the  metals  concerned.  These seventeen
    plants are 6-7, 6-37, 11-8, 15-3, 19-11, 19-24,  20-17,  20-
    24,  23-7,  30-3, 30-21, 33-2, 33-5, 33-20, 33-2U,  36-1, and
    36-12.  Visits were made to six plants  (11-8,  33-20,  36-1,
    36-12,  33-5,  15-3)  for the gathering of samples  and plant
    data on  several  of  the  processes  at  these  plants  and
    analyzed.   Of these six, three  (11-8,  33-20, and 36-1) were
    studied in great detail.  The results of  these  visits  are
    compiled in the following pages.
    
    Plant 11-8
    
    Plant  11-8 is representative of a large job shop (about 170
    employees) which contracts to do electroplating  of  copper,
    nickel,  chromium,  zinc, and cadmium,  along with chromating
    and phosphating on a large variety  of  parts.   This  plant
    operates  automatic rack, automatic barrel, manual hoist and
    barrel lines, and other specialized manual lines.
    
    Plant 11-8 was identified as achieving  good  waste-effluent
    control  by  a  combination of batch and continuous chemical
    treatment  on   mixed   wastes   from   the   electroplating
    operations.   Waste  treatment also includes the special in-
    process control operations of ion exchange and  evaporation.
    A  combination anion-cation exchanger processes the chromium
    plating rinse waters from three separate lines for reuse.  A
    300-gph evaporator serves two large zinc plating lines on an
    open loop basis.
                                  185
    

    -------
    Most of the plant processes were operated  20  hours  a  day
    (two  10-hour  shift basis), with some plating units running
    as many  as  22  hours  a  day.   Working  hours  were  also
    staggered  to  some  extent,  so  that the load on the waste
    treatment plant was fairly  uniform  throughout  the  entire
    day.
    
    Figure 23 is a schematic presentation of the waste treatment
    operation  at  Plant 11-8.  The triangulated points indicate
    waste stream sampling points.  The  figure  also  shows  the
    estimated flow rates for the various waste streams.
    
    Effluent  analyses  are  presented  in  Table 34.  The table
    shows data for the first 24-hour period, the  second  period
    of  9  hours,  and  the combined period of 33 hours.  As the
    average flow rates for the 24-hour and 9-hour  periods  were
    very  close, (i.e., 25,565 gph and 25,000 gph, respectively)
    the chemical analyses for the two periods were  combined  in
    the  ratio   of their total flows to provide an analyses for
    the combined period.  The weighted percentages  employed  to
    arrive  at  an analysis for the total 33-hour period were as
    follow:
    
              1st period        613,600   x 100  = 73.17 percent
                                838,600
    
              2nd period        2.2.5x000   x 100  =26.83 percent
                                838,600
    
    Cyanide_Treatment^System_Results
    
    Cyanide waste treatment is carried out  automatically  on  a
    batch  basis  in  either of two 25,000 gallon tanks.  Sodium
    hydroxide is automatically added by  a  pH-controller  unit,
    while  an  oxidation-reduction potential unit (ORP) controls
    the chlorine addition.  Each tank is equipped with  its  own
    control units.
    
    Samples  of several batches of untreated cyanide wastes were
    taken from the tank contents while the tank was  filling  at
    sample  point  1.   Samples of treated batches of waste were
    taken upon completion of the destruction step when the  tank
    was being emptied at sample point 2.  Data on sampling times
    and  the  compositing of grab samples taken from the cyanide
    waste  stream  before  and  after  treatment,   along   with
    analytical  results,  are  given  in  Table 35.   The percent
    cyanide destruction was as follows:
    
              38^.9
              42.T x 100 = 92.4 percent
                                   186
    

    -------
               TABLE 34      COMPARISON OF TREATMENT RESULTS WITH EFFLUENT GUIDELINE REQUIREMENTS
                             FROM SAMPLING PROGRAM ON PLANT 11-8 OPERATIONS
    
    
    
    Metric
    Units
    Guideline
    
    Item
    Cd
    CrVI
    Cr,
    total
    Cu
    Fe
    Ni
    Zn
    CN
    (oxid)
    CN,
    total
    POi
    TSS
    pH
    (a) The
    (b) The
    Value,
    mg/sq m
    80
    8
    80
    
    80
    160
    80
    80
    8
    
    80
    
    160
    3,200
    6.0 to 9.5
    
    English
    
    
    /•„ N
    24-Hour Period^'
    Units
    Guideline Cone, in
    Value,
    lb/106 sq
    16.4
    ].6
    16.4
    
    16.4
    32.7
    16.4
    16.4
    1.6
    
    16.4
    
    32.7
    654
    —
    water/area processed
    effluent
    sample for
    Effluent^),
    ft mg/1
    0.21
    0.03
    0.05
    
    0.11
    0.11
    0.60
    0.74
    0.47
    
    0.48
    
    0.08
    230 (b)
    —
    relationships for
    the 24-hour period
    Effluent
    Discharge
    mg/
    sq m
    27.0
    3.9
    6.4
    
    14.1
    14.1
    77.0
    95.0
    60.3
    
    61.6
    
    10.3
    (b)
    —
    the
    was
    lb/10b
    sq ft
    5.5
    0.80
    1.31
    
    2.9
    2.9
    15.8
    19.5
    12.35
    
    12.6
    
    2.1
    (b)
    —
    
    r _\
    9-Hour Period^'
    Cone.
    Combined
    33-Hour Period(a)
    Combined
    Effluent Weighted Effluent
    in Discharge Cone, in Discharge
    Effluent*^), mg/
    lb/10b Effluent, mg/
    mg/1 sq m sq ft
    0.21
    0.03
    0.03
    
    0.16
    0.03
    0.60
    0.35
    0.26
    
    0.27
    
    0.05
    <10
    8.8
    three periods are
    collected
    22.7
    3.2
    3.2
    
    17.3
    3.2
    64.7
    37.8
    28.1
    
    29.1
    
    5.4
    <1,079
    —
    given in Table
    in a 2-1/2-gallon jug
    4.7
    0.66
    0.66
    
    3.5
    0.66
    13.2
    7.7
    5.8
    
    6.0
    
    1.1
    <221
    — —
    11-8-11
    to which
    mg/1
    0.21
    0.03
    0.045
    
    0.12
    0.09
    0.60
    0.635
    0.41
    
    0.42
    
    0.07
    (b)
    — —
    later
    about
    sq m
    25.7
    3.7
    5.5
    
    14.7
    11.0
    73.3
    77.6
    50.1
    
    51.3
    
    8.6
    (b)
    __
    lb/106
    sq ft
    5.3
    0.76
    1.13
    
    3.0
    2.3
    15.0
    15.9
    10.3
    
    10.5
    
    1.8
    (b)
    __
    in the report.
    20-25 pellets of
    sodium hydroxide had been added by  Plant  11-8  personnel  to  preserve  the  cyanide.   Sample  collection was made
    using the Plant 11-8 Sigmamotor WA-2  composite sampler which withdrew a  small  volume of effluent  at 5-minute
    intervals.  The pH of the collected sample  for the  24-hour  period  (volume  -  2.5 gallons)  was  10.8.   The pH  of  a
    grab sample of effluent taken during  this period  by Plant 11-8  personnel was measured at  8.5.   The  presence of
    the caustic pellets in the collection jug is believed responsible  for the  high TSS value, as  it caused precipi-
    tation of solids which analyzed mostly calcium and  magnesium.   Analysis  of the suspended  solids (TSS) for  the
    24-hour period showed 51.0 mg/1 of  calcium  and 42.0 mg/1 of magnesium.   Durirg the second period, the sample
    was collected in a container without  caustic pellets and a  TSS  value of  <10  mg/1  was obtained.   The actual
    collection time for the second period was from 0810 to  1610 (6/7/74), as a container without  caustic pellets
    was used  to replace the caustic containing  jug put  into  use at  0700  (6/7/74).
    

    -------
                    TABLE 35
    CYANIDE TREATMENT RESULTS
          Sample No.  and Description
                                                      Concentration, mg/1
                     Total
                    Cyanide
    Oxidizable
     Cyanide
    11-8-CN-B-COMP (Before CN Treatment)
      This was a composite of 2 grab
      samples mixed in equal proportions;
      the samples were taken at the
      following times:  6/6/74 (0845)  and
      6/7/74 (1035).
                     43.0
      42.1
    11-8-CN-A-COMP (After CN Treatment)
      This was a composite of 4 grab
      samples mixed in equal proportions;
      the samples were taken at the
      following times:  6/6/74 (1058) and
      6/7/74 (0100,0940, and 1450).
                      3.2
       3.2
                                    188
    

    -------
                             *>.
                                                                                          fr-
    VO
                                                  Cyanide A
    
                                                  25,000 gal
                                                         Strong
                                                          Acid
                              Dilute Acid-Alkali
                                ^18,000
                                           Neutralization
    
                                            120,000 gal
    Clarifier
    60,000 gal
                                                                                            Sludge
                                                                                          To Lagoon
    ^25,500 gph
           FIGURE  23
                                                                                      Strong
                                                                                      Alkali
    WASTE TREATMENT OF PLANT  11-8 EFFLUENTS EY COMBINATION BATCH-CONTINUOUS CHEMICAL TREATMENT
    
    Flows shown are approximate for  treatment of 25,500 gph effluent.
    

    -------
    Results^of ^Chromate Reduction
    
    As indicated in Figure 23, treatment of the chromium  wastes
    is  carried  out automatically on a batch basis in either of
    two  6000-gallon  tanks  using  sulfur  dioxide  (SO2)    and
    sulfuric acid.  The acid and SO2 additions are automatically
    controlled  by- the  use  of pH and ORP units, respectively.
    Grab samples of several batches of untreated chromium stream
    wastes were taken while the tank  was  filling  at  sampling
    point  3.   Grab  samples  of  treated batches of waste were
    taken upon completion of the reduction step  when  the  tank
    was being emptied at sampling point U.
    
    Data on sampling times and compositing of grab samples taken
    from  the  chromium waste stream before and after treatment,
    along with analytical results, are given in Table  36.    The
    percentage reduction of Cr*6 to Cr*3 was as follows:
    
              2^97
              3.00 x 100 = >99.0 percent
    
    This result indicates very efficient reduction of hexavalent
    chromium with the batch SO2 treatment.
    The  arrangement  of  Plant  11-8's  piping  did  not permit
    sampling  of  the  acid/alkali  stream   before   treatment.
    Analysis of samples taken at points 5 and 6 give total metal
    concentrations before and after clarification.  See Table 37
    
    Effectiveness of Clarifier^in Lowering^Waste
    Content of Effluent Stream
    
    An  analysis  of  the  metal content of grab sample from the
    neutralization tank contents (sample taken  at  Triangulated
    Point  5,  Figure  23)  was  carried  out  to  determine the
    effectiveness  of  the   precipitation   and   clarification
    procedures in removing wastes from the effluent stream.  The
    analytical  data  on  the  effluent  stream before and after
    clarification are shown in Table 37.  Although  a  grab  and
    composite sample are being compared in Table 37 , it gives an
    approximation  of  clarifier  efficiency.  The reduction for
    the various metals ranged  from  89  to  98  percent,  which
    indicates  that  the clarifier was doing an effective job in
    lowering the waste content in the effluent stream.
    
    Sampling Effluent
                                  190
    

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                    TABLE  36      CHROMIUM TREATMENT RESULTS
                                                      Concentration, mg/1
                                                   Hexavalent         Total
           Sample No.  and Description                  Cr              Cr
    
    
    11-8-Cr-B-l (Before S02 Reduction)                 3.1              5.2
      [This was a composite of 4 grab
      samples taken at the following
      times:  6/6/74 (0900, 1310, 2250)
      and 6/7/74 (0710);  equal amounts
      from each grab sample were used
      to make the composite.]
    
    11-8-Cr-A-l (After S02 Reduction)                 <0.03            17.0
      [This was a composite of 7 grab
      samples mixed in equal proportions;
      the samples were taken at the following
      times:  6/6/74 (0914, 1113, 1330,  1540,
      and 2230) and 6/7/74 (0745, 1535).]
                                     191
    

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                TABLE 37       EFFECTIVENESS OF CLARIFIER IN LOWERING THE
                               METALLIC PRECIPITATE CONTENT IN THE EFFLUENT
                               STREAM
                                                     Metal Concentration, mg/1
                                                     Total
                    Item                       Cu     Cr     Ni     Cd     Fe     Zn
    
    
    Neutralization Tank Effluent               1.64   1.95   5.65   3.10   7.81  15.0
      (Grab sample taken 6/6/74 at 1415)
    
    Clarified Effluent                         0.11   0.05   0.60   0.21   0.11   0.74
      6/6/74 (0700) to 6/7/74 (0700)
    
    Reduction in Metal Content of Effluent    93.3%  97.4%  89.4%  93.2%  98.6%  95.1%
                                       192
    

    -------
    Plant  effluent  was  sampled   with   a   Sigmamotor   WA=2
    (Sigmamotor   Inc,  Middleport,  New  York   14105)   sampler
    belonging to Plant 11-8.  This unit collected about 33 ml of
    effluent at 5.5 minute intervals throughout  the  first  24-
    hour  sampling  period  from 6/6/74 (0700)  to 6/7/74 (0700) .
    The rate of withdrawal was  about  1  ml  per  second.    The
    frequency  of  effluent  withdrawal  was  increased  for the
    following 9-hour sampling  period  in  order  to  provide  a
    greater  amount  of  sample.   About  33 ml of effluent were
    withdrawn at about 2.5 minute intervals, at a rate of  about
    1 ml per second.  The effluent sampling location is shown as
    Triangulated  Point  6  on  the  waste  treatment  flowsheet
    presented in Figure 23.
    
    Waste Stream Flow Data
    
    Effluent Flow Data
    
    Instantaneous effluent flow  rates  were  read  periodically
    from  a  recording  chart  and cumulative flowmeter readings
    were also taken periodically during the visit.
    
    Instruments for measuring and recording  instantaneous  flow
    and  for  indicating cumulative volume were operating in the
    plant.  The cumulative meter was used to  calculate  average
    flow except during a malfunction from 0700 to 1800 on 6/6/74
    for  which  period  readings  on the instantaneous flowmeter
    were averaged.
    
    Summarized effluent flow data for the 24-hour and the 9-hour
    sampling periods are presented in Table 38.
    
    Intermediate Stream Flow Data
    
    The following estimates of flow rates for  the  intermediate
    streams  making  up  the  total plant effluent were obtained
    from discussions with plant personnel:
    
              Cyanide Stream             5,200 gph
              Chromium Stream            2,300 gph
              Acid/Alkali Stream        18,000 gph
              Combined Stream Total     25,500 gph
    
    Area^Processed
    
    The estimation of the areas  processed  at  Plant  11-8  was
    based  on  measurements on representative parts on each line
    and  tying  in  these  areas  with  processing  rates.    The
    individual  part  areas, together with data on the number of
    parts processed per unit time either on racks or in barrels,
                                  193
    

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                 TABLE  3 8
    SUMMARIZED EFFLUENT FLOW DATA
              Time Interval
                                  Average Hourly
                  Total Flow,       Flow Rate,
                      gal               gph
    6/6/74 (0700 to 1800)
    6/6/74 (1800) to 6/7/74 (0700)
    
    24-Hour Period
      6/6/74 (0700) to 6/7/74 (0700)
    
    9-Hour Period
      6/7/74 (0700 to 1600)
    
    Total 33-Hour Period
      6/6/74 (0700) to 6/7/74 (1600)
                    289,600
                    324,000
    
                    613,600
                    225,000
                    838,600
    25,565
    25,000
    25,410
                                194
    

    -------
    were used to determine an average value  of  area  processed
    per  hour.   This  hourly  value multiplied by the number of
    operations on the line and then multiplied by the  hours  of
    operation   during  the  sampling  period,  gave  the  total
    processed area for the particular line.
    
    Summarized data on the areas processed on each of the  lines
    are  presented in Table 39.  The area processed on each part
    was taken as the total area that was  rinsed  on  the  part.
    Thus,  with  tubular  products,  in which the inner surfaces
    receive little or no plate but are rinsed, the inner surface
    areas  were  counted  as  processed  area.   The  qualifying
    operations  in  the  overall  plating  or coating operations
    carried  out  on  each  line  are  indicated  in  the  line-
    description column of Table 39.
    
    Water^Use/Area,Processgd Relationship
    
    Summarized  data  on  water use/area processed relationships
    for the Plant 11-8 operations during the three  periods  are
    presented in Table HO.
    SAMPLING AND ANALYSIS TOF PLANT 33-20
    
    Introduction^and Rationale for Sampling PlantT33-20
    
    Plant 33-20 is a medium-sized manufacturing facility for the
    fabrication   and  assembly  of  refrigeration  thermostats,
    temperature  controls,  valves,  and  other  hardware.   The
    captive electroplating shop when operating under normal two-
    shift  conditions  employs  about  16  people, but under the
    reduced work load during the latter part of August when  the
    visit was made, the number of employees was down to 10.  The
    waste  treatment  plant,  which is run in conjunction with a
    water-purification operation employs  one  man  on  each  of
    three shifts, plus supervision.
    
    The main operation producing effluents are two tin automatic
    rack lines and several bright dipping processes on brass and
    copper   parts.   Other  operations  contributing  to  waste
    effluents include: zinc  barrel  and  rack  plating,  copper
    barrel  and rack plating, cadmium barrel plating, tin barrel
    plating, and nickel rack plating.
    
    Plant 33-20 was identified as achieving good waste  effluent
    control by continuous chemical treatment on mixed wastes.
    
    Figure 24 is a flow sheet for the waste treatment operations
    at  the plant.  The Cyclator is a combination precipitation-
                                   195
    

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                         TABLE 39
    SUMMARIZED DATA ON AREAS PROCESSED ON VARIOUS PLANT 11-8 LINES
    10
    a\
    m ,__, Total Processed Area During Period
    
    
    
    Line Description
    Zinc Automatic Rack Line
    (Zn + Chromate)
    Stevens Ni-Cr Automatic Rack Line
    Cu-Ni-Cr Manual Hoist Rack Line
    (Cu + Ni 4- Cr, Ni -f Cr, or Ni + brass)
    Zinc Manual Hoist Rack Line
    (Zn -i- Chromate)
    Cadmium Automatic Rack Line
    (Cd 4- Chromate)
    Hard Chromium Rack Line
    M&T Zinc and Cadirium Aut. Barrel Line
    (Zn + Chromate)
    VIP Zinc Automatic Barrel Line
    (Zn + Chromate)
    Cu-Ni and Cd Manual Barrel Line
    (Cu 4- Ni or Cd 4- Chromate)
    Nickel Manual Barrel Line
    (Cu 4- Ni)
    Phosphating Line
    (Line uses barrels or baskets)
    Combined Lines (Total Area Processed)
    
    Number
    of
    Operations
    2
    
    2
    2 or 3
    
    2
    
    2
    
    1
    2
    
    2
    
    2
    
    2
    
    1
    
    —
    XU LCU.
    Area
    Processed
    per Hour,
    sq ft/hr
    570
    
    1510
    1530
    
    270
    
    550
    
    2
    1355
    
    1835
    
    885
    
    360
    
    1105
    
    —
    Period
    6/6(0700) to
    Hr of
    Operation
    20
    
    20
    22
    
    12
    
    12
    
    15
    22
    
    22
    
    20
    
    10
    
    16
    
    —
    6/7(0700)
    Area,
    sq ft
    11,400
    
    30,200
    33,700
    
    3,240
    
    6,600
    
    30
    29,810
    
    40,370
    
    17,700
    
    3,600
    
    17,680
    
    E194,330
    Period
    6/7 (0700 to
    Hr of
    Operation
    9
    
    9
    9
    
    9
    
    —
    
    9
    9
    
    9
    
    9
    
    9
    
    9
    
    —
    1600)
    Area,
    sq ft
    5,130
    
    13,590
    13,770
    
    2,430
    
    —
    
    30
    12,195
    
    16,515
    
    7,965
    
    3,240
    
    9,945
    
    284,800
    

    -------
                              TABLE 40
    WATER USE/AREA PROCESSED FACTORS FOR THREE PERIODS
    H
    vo
    Period
    1st
    2nd
    Combined
    Duration,
    hr
    24
    9
    33
    Water Used
    B-al
    613,600
    225,000
    838,600
    liters
    2,319,410
    850,500
    3,169,910
    Area Processed
    sq ft
    194,330
    84,800
    279,130
    s q m
    18,060
    7,880
    25,940
    Water Use-
    Area Factor,
    gal/sq ft
    3.16
    2.65
    3.00
    1/sq -m
    128.4
    107.9
    122.2
    

    -------
    OT
    /^
    \
    j
    1 Alkali-Cyanide ,
    i Holding Tank {-
    j ~14,000 gal |
    L 	 	 i
    Liquid
    Causti
    ci2
    '? T >..
    -3600 gph
    c
    ... !
    Cyanide-
    Treatment
    Tank No. 1
    ~2800 gal
    __
    I
    i
    i
    i
    Cyanide
    Treatment
    Tank No. 2
    -2700 gal
          |Acid-Chromium i
           Holding Tank
          [  -13,000 gal
    -2400 gph
       Chromium
    Treatment Tank
       -4800 gal
                                                                Lime
                                                                              Lime
                                                            Coagulant
                                                                i
    i _ i. _.
    \ | Mix
    i Tank
    / ; -2600 gal
    •
    
    \
    • I/
    I
                                                                                                              Solids to
                     FIGURE  24        WASTE TREATMENT OF PLANT 33-20 EFFLUENTS BY CONTINUOUS CHEMICAL TREATMENT
    
                                      Flows shown are approximate for treatment of 6000 gph of effluent.
    

    -------
    clarification unit; it was 20 ft in diameter and 20 ft high.
    The  triangular  points  indicate  waste   stream   sampling
    locations.  Estimated flow rates for the various streams are
    also shown on the flow diagram.
    
    The  overall  plant visit covered a period of 72 hours, or 3
    separate days in which the treatment plant processed  wastes
    on the average of 7 hours each day, while the electroplating
    and  bright  dipping  operations required 17 hours each day.
    The holding tanks served to collect and store wastes  during
    the  low  electroplating production hours when the treatment
    plant was shut down and not processing wastes.
    
    Cyanide^Destruction Results
    
    Cyanide treatment is carried out on a continuous basis using
    a series of two tanks; the wastes flow through  Tank  No.  1
    and then Tank No. 2.  As indicated in Figure 24r chlorine is
    metered  into  the  alkali-cyanide stream at a rate of about
    8.4 Ib/hour and liquid caustic (50 percent NaOH)  is added to
    maintain the pH in the treatment tanks between 9.0 and 10.0,
    and preferably between 9.0 and 9.5.  The Tank No. 2 contents
    are checked for pH hourly, and also checked  by  the  ortho-
    tolidin  test  for  the  persistence  of  residual  chlorine
    indicating completion of the destruction reaction.  Chlorine
    and/or caustic feed rates are adjusted manually.  The  total
    retention time taking into account both treatment tanks with
    an  estimated  alkali-cyanide  stream  flow  of 3600 gph was
    about 90 minutes.
    
    Thirteen 1-liter samples over a period  of  four  days  were
    taken at sampling point 1 of untreated cyanide wastes in the
    holding tank.
    
    Equal portions of these samples were combined to provide the
    composite sample of untreated cyanide submitted for analyses
    (Table 41, Sample No. 33-20-CN-B-1-COMP.).
    
    The  treated  alkali-cyanide  stream  was  sampled for three
    consecutive days at sampling point 2 with a Sigmamotor  WA-2
    (Sigmamotor  Inc,  Middleport,  New  York  14105) unit which
    collected about  42  ml  of  treated  waste  at  5.4  minute
    intervals during the treatment plant processing periods.
    
    Equal portions of these samples were combined to provide the
    composite  sample  submitted  for analysis (Table 41, Sample
    No. 33-20-CN-A-1-COMP).
                                   199
    

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                          TABLE 41
                CYANIDE TREATMENT RESULTS
    Sample
     No.
           Description
      Concentration, mg/1	
    Oxidizable            Total
      Cyanide            Cyanide
    33-20-CN-B-l-COMP
    33-20-CN-A-l-COMP
    Composite Sample, before
      cyanide treatment
    
    Composite sample: after
      cyanide treatment
       67.0
       0.01
    67.4
     0.05
                                              200
    

    -------
    The low oxidizable cyanide content of 0.01  in  the  treated
    cyanide  stream shows that effective cyanide destruction was
    achieved.  The percent cyanide destroyed was as follows:
    
              67.0 - 0.01
                 67.0         (100) = 99.98 percent.
    
    This high  percent  removal  further  attests  to  effective
    cyanide treatment at Plant 33-20.
    
    Chromium^Reduction^Results
    
    The  treatment  of the acid-chromium waste stream is carried
    out on a continuous basis using a single  flow-through  tank
    (4800  gal).   Addition  of  the  sulfur  dioxide   (SO2)  is
    controlled manually.  An ORP unit is  used  to  monitor  the
    reduction,  and  a  reading  of  400  mv is maintained.  The
    reduction is carried out at the pH  of  the  incoming  acid-
    chromium waste stream, which normally runs about 0.8 to 1.0.
    The  retention  time in the chromium treatment tank based on
    an estimated flow of 2100 gph was 120 minutes.
    
    Thirteen 1-liter samples over a period  of  four  days  were
    taken  at  sampling  point  3 of the untreated acid-chromium
    wastes in the holding tank.
    
    Equal portions of these samples were combined to provide the
    composite  sample  of  untreated  chromium   submitted   for
    analyses (Table 42, Sample No. 33-20-Cr-B-1-COMP) .
    
    The  treated  acid-chromium  stream  was  sampled  for three
    consecutive days at sampling point 4 with a Sigmamotor  WA-2
    unit  which  collected  about  34 ml at 5.3 minute intervals
    during the treatment plant processing periods.
    
    Equal portions of the samples  of  treated  chromium  stream
    wastes   were  combined  to  provide  the  composite  sample
    submitted for analysis (Table 42, Sample  No.  33-20-CR-A-1-
    COMP).
    
    The  analytical  results, presented in Table 41, showed that
    effective reduction of the hexavalent chromium was achieved,
    since the Cr+* concentration in the treated stream was <0.05
    mg/1.   Using  the  data  from  Table  41,  the   percentage
    reduction of Cr*6 to Cr+3 was as follows:
    
                3.8 - 0.05
                    3.8  ~  x 100 = >98.7 percent
                                   201
    

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                        TABLE  42
                CHROMIUM REDUCTION RESULTS
    Sample
     No.
         Description
                                      Concentration, mg/1
    Hexavalent Cr
    Total Cr
    33-20--CR-3-1-COMP
    33-20-CR-A-l-COMP
    Composite sample before
      S02 reduction of
      chromium
    
    Composite sample after
      S0£ reduction of
      chromium
        3.8
       <0.05
      11.1
       7.9
                                           202
    

    -------
    The above results indicate effective reduction of hexavalent
    chromium with the continuous SO2 treatment.
    
    Effectiveness of .Precipitation(Treatment_of_Acid-Alkali
    StreamL-ClarificatiQn^Operations in Lowering the
    Waste contentmofthejEffluent_Stream
    
    An  analysis of the metal content of a composite of periodic
    grab  samples  of  mix  tank  contents   (samples  taken   at
    Triangular  Point 5, Figure 24)  was carried out to determine
    the effectiveness of  the  precipitation  and  clarification
    procedures  in removing wastes from the effluent stream.  As
    shown in Figure 24,  the  alkali-cyanide  and  acid-chromium
    streams  flow together into the mix tank where lime is added
    to maintain the pH  between  4.0  and  6.0,  and  preferably
    between 5.0 and 6.0.  The addition of lime to the pH tank is
    governed by a pH controller.
    
    Nine  1-liter samples were taken over a period of three days
    of the mix tank contents.
    
    Equal portions of the above 9 grab samples were combined  to
    provide  the composite sample of mix tank contents submitted
    for analyses (Table 43, Sample No. 33-20-MN-1-COMP).
    
    The analytical data on the effluent waste stream before  and
    after  precipitation-clarification  are  given  in Table 42.
    The reduction in concentrations for six of the seven  metals
    ranged  from  80  to  95  percent,  which indicates that the
    precipitation-clarification are  given  in  Table  42.   The
    reduction  in  concentrations  for  six  of the seven metals
    ranged from 80 to  95  percent,   which  indicates  that  the
    precipitation-clarification    steps   were   effective   in
    substantially lowering the waste  content  in  the  effluent
    stream.    Even with the seventh metal, nickel, the reduction
    was 61 percent which was good considering the  low  influent
    concentration  of  0.23  mg/1  Ni  and  the  final  effluent
    concentration of 0.09 mg/1 Ni.
    
    Plant effluent was sampled with a B.I.F. (Builder Industrial
    Factory, Providence,  Rhode  Island)   sampler  belonging  to
    Plant 33-20.  This unit collected about 36 ml of effluent at
    5.0  minute  intervals  during  the  actual periods when the
    waste treatment processing was being carried out.  The  rate
    of  collection  is  about  2 ml per second.  The effluent is
    sampled immediately after the effluent leaves  the  Cyclator
    and the location is shown as Triangular Point 6 on the waste
    treatment flow sheet of Figure 24.
    
    Waste Stream Flpw_Data
                                   203
    

    -------
             TABLE 43        EFFECTIVENESS  OF PRECIPITATION-CLARIFICATION
                             OPERATIONS  IN  LOWERING WASTE CONTENT OF
                             EFFLUENT STREAM
                                                   Metal Concentration,  mg/1
                                                  Total
                Item                          Cd    Cr    Cu    Fe    Ni    Sn    Zn
    
    Mix tank contents composite sample       0.15   1.4   22.4  1.9  0.23   6.0   4.1
      (Sample No.  33-20-MN-l-COMP)
    
    Clarified effluent  (Combined            0.03   0.20   1.5  0.18 0.09   0.33  0.39
      effluent for August 20 to 22,
      see Table 33-20-1,  right side
      columns)
    
    Reduction in metal content of           80.0% 85.7%  93.3%  90.5%  60.9% 94.5%  90.5%
      effluent
                                        204
    

    -------
    Intermediate Stream and Effluent Flow Data
    
    Plant  33-20  personnel  combine the flow rate data from the
    alkali-cyanide and the acid-chromium streams  to  arrive  at
    the  total  effluent  flow.   The  plant is equipped with an
    instantaneous flow indicator  and  also  a  cumulative  flow
    meter  on  each  stream.   Unfortunately, at the time of the
    visit the instantaneous flow indicator on the  acid-chromium
    stream  was  not functioning, and the instantaneous readings
    on the alkali-cyanide stream  unit,  although  not  accurate
    (too low by about 20-25 percent) served to indicate that the
    pumping  conditions  on  the stream were being maintained to
    provide a steady flow rate.
    
    Plant 33-20 personnel adjust the pressure settings governing
    the Conoflow valves to regulate the pumping rates of each of
    the  two  streams.   By  keeping  these  pressure   settings
    properly  adjusted,  steady pumping rates on each stream can
    be maintained  during  the  treatment  period  cycles  which
    averaged  about  7  hours  each day during the 3 days of the
    plant visit.  Flow rate and pH data during the days  of  the
    visit for the periods in which the waste treatment plant was
    processing waste streams are presented in Tables 44, 45, and
    46, respectively.  Plant 33-20 personnel indicated that from
    experience  with their known pressure settings governing the
    Conoflow valves, the cumulative flowmeter  readings  on  the
    alkali-cyanide  stream  were  about  5  percent  higher than
    actual flows and the cumulative flowmeter  readings  on  the
    acid-chromium stream unit were about 10 percent low.
    
    The  flow  rates  of the total effluent leaving the Cyclator
    were measured by going down into a man-hole pit about 50  or
    60  feet  downstream  from  the Cyclator and noting the time
    required for 5  gallons  of  effluent  to  be  caught  in  a
    calibrated  container.  The effluent flow data for the three
    days are presented in Table 47.  As can  be  seen  from  the
    tabulated  flow  data.  Plant   33-20  personnel by carefully
    controlling the pressures governing the Conoflow valves were
    able to maintain steady flows on the two streams during  the
    waste treatment plant operating periods.  The alkali-cyanide
    stream  accounts for about 60 percent and the acid-Cr stream
    for about 40 percent of the total effluent flow.
    
    From an  examination  of  the   pH  values  of  the  Cyclator
    contents listed in Tables  44, 45 and 46, it can be seen that
    the  plant experienced some problems at times in maintaining
    the pH in the range of 7.0 to 8.5, and preferably  at  about
    8.0.   Even  though the lime additions were governed by a pH
    controller, somewhat erratic lime feeds occurred  at  times.
    As  can be seen from Tables 43  and 44 the pH was above 10 at
                                    205
    

    -------
                      TABLE  44       WASTE STREAM AND EFFLUENT FLOW DATA  CORRESPONDING
                                      TO THE ELECTROPLATING PRODUCTION  FOR AUGUST  20,
                                      1974(a)
    
    
    
    Alkali-Cyanide Sl.ream
    
    
    Date Time(a)
    8/20/74 0815
    0833
    1007
    1030
    1125
    1155
    1225
    1325
    1335
    1407
    1436
    1530
    Instantaneous
    Flow-Rate
    Reading (fe), gpm
    ~45
    43
    44
    44
    45
    44
    45
    45
    44
    44
    44
    44
    Cumulative
    1'lowmeter
    Reading (c), 10 gal
    8:.26889
    8:.26999
    7547
    7676
    8014
    8196
    8376
    8749
    8781
    8980
    9160
    8129538(d)
    Acid-Chromium
    Stream(b)
    Cumulative
    Flowmeter
    Reading 
    -------
                        TABLE   45      WASTE STREAM AND EFFLUENT FLOW DATA CORRESPONDING TO THE
                                        ELECTROPLATING PRODUCTION FOR AUGUST 21,  1974(a)
    to
    o
    Date Time
    8/21/74 0845
    0908
    0938
    1010
    1100
    1125
    1143
    1215
    1300
    1420
    1502
    1516
    1530
    Alkali-Cyanide
    Stream
    Instantaneous Cumulative
    Flow Rate Reading (b), Flowmeter Reading'0',
    gpm 10 gal
    -44
    44
    44
    44
    44
    43
    44
    44
    44
    43
    43
    43
    43
    8129538
    8129652
    8129832
    8130030
    0378
    0470
    0574
    0772
    1045
    1454
    1696
    1772
    8131882 (d)
    Acid-Chromium Stream
    Cumulative
    Flowmeter Reading (c',
    10 gal
    0191500
    0191568
    1670
    1784
    1983
    2036
    2094
    2208
    2362
    2626
    2767
    2812
    01912873 W)
    Effluent in
    Cyclator,
    pH
    10.2
    10.2
    10.6
    10.4
    9.5
    9.0
    8.6
    8.2
    8.0
    7.8
    7.8
    7.8
    7.8
           (a)(b)(c)  See corresponding footnotes to Table 33-20-5.
           (d)  The stream flows for the period are given below:
                      Stream
    
                      Alk-CN
                      Acid-Cr
    Flow From Meter
     Readings, gal
         23,440
         13,730
    Estimated Flow
      Correction
    
        5% High
       10% Low
         Corrected
         Flow, gal
    
           22,268
           15,103
    
    Total  37,371
    

    -------
    TABLE
                                        WASTE STREAM AND EFFLUENT FLOW DATA  CORRESPONDING  TO  THE
    
                                        ELECTROPLATING PRODUCTION  FOR AUGUST  22,  1974 (a)
    o
    00
    Alkali- Cyanide Stream
    
    Instantaneous
    Flow Rate Reading^
    Date Time
    8/22/74 0845
    0922
    0930
    0940
    1005
    1030
    1050
    1100
    1120
    1150
    i22j
    1320
    1342
    1415
    1443
    150.6
    1520
    1530
    gpm
    -44
    44
    44
    44
    44
    44
    44
    44
    44
    44
    44
    44
    44
    44
    44
    44
    44
    44
    (a)(b)(c) See corresponding footnotes
    (d) The stream flows
    
    Stream
    Alk-CN
    Acid-Cr
    
    Cumulative ,
    '', Flowmeter Reading^0 ,
    10 gal
    8131882
    8132116
    2170
    2230
    2382
    2518
    2642
    2702
    2819
    3012
    3214
    3565
    3683
    3904
    4054
    4189
    4289
    8134370
    to Table 33-20-5
    Acid-Chromium Stream
    Cumulative
    Flowmeter Reading (°',
    10 gal
    0192873
    0193005
    3055
    3092
    3181
    3262
    3334
    3368
    3435
    3546
    3660
    3865
    3932
    0194055
    4140
    4217
    4271
    0194320
    
    
    Effluent in
    Cyclator ,
    PH
    7.8
    9.7
    9.3
    9.2
    8.5
    8.2
    8.1
    8.3
    8.1
    8.2
    7.5
    7.1
    
    7.6
    7.7
    6.9
    7.1
    6.9
    
    for the period are given below:
    Flow From
    Readings ,
    24,880
    14,470
    
    Meter Estimated Flow
    gal Correction
    5% High
    10% Low
    
    Corrected
    Flow, gal
    23,636
    15,917
    Total 39,552
    
    
    
    
    
    

    -------
    TABLE  47       FLOW RATE DATA FOR TOTAL EFFLUENT
                    STREAM LEAVING THE CYCLATOR
    Date
    8/20/74
    
    
    
    8/21/74
    
    
    
    
    
    
    8/22/74
    
    
    
    
    
    -_,.
    Flow
    Volume,
    Time gal
    1350 5
    5
    5
    5
    0925 5
    5
    5
    
    1410 5
    5
    5
    0940 5
    5
    5
    
    1400 5
    5
    5
    Time,
    sec
    3.0
    3.2
    2.8
    3.0
    3.0
    3.2
    3.1
    
    3.0
    3.2
    3.0
    3.0
    2.8
    3.1
    
    2.8
    3.0
    3.0
    Average Average Time Average Hourly
    Time, For Day, Flow Rate,
    sec sec gal
    
    3.0 3.0 6000
    
    
    
    3.1
    
    3.08 5844
    
    3.07
    
    
    2.97
    
    2.95 6102
    
    2.93
    	
                         209
    

    -------
    the end of the first treatment period and above  10 for  about
    2  1/2 hours at the  start of  the  second  treatment  period.
    These  high  pH  values  may  have  been responsible for the
    highest TSS concentration  in the  effluent  for  the  second
    period,  in  that   it  may have produced a precipitate that
    settled less readily.
    
    Table 48 gives the  holding tank levels at the start and end
    of  the  waste  treatment  processing periods for the various
    days of the visit.  These  readings were used in  conjunction
    with  measured effluent outflows to calculate the volumes of
    the waste streams for each day of the visit.
    
    The total waste stream generated in the  electroplating and
    metal   finishing   operations  for  the  various  days  were
    determined using the flow  rate  and  holding  tanks  liquid
    level data presented in Tables 47 and 48, respectively.
    
    The  total  waste   flow  corresponding to the production for
    August 20 was determined as follows:
    
        Hours of waste  treatment plant processing:  0815
          to 1530 = 7.25 hr
        Average hourly  effluent flow rate (Table 33-20-8)
          = 6,000 gph
        Total effluent  flow during 7.25-hour period =
          6,000 (7.25)   = 43,500 gal
        Corrections for changes in holding tank levels
          (Table 33-20-9)
        Alkali-CN tank level rise:  69.4 - 54.0 =
          +15.4 in; 15.4 (133  gal) = + 2,048 gal
        Acid-Cr tank level drop: 42.0 - 36.0 = 6.0;
          -6.0 (117)  = -702 gal
        Adjustment for  30 minutes extra operation time
          (i.e.,  0815 to 0845)  = 2550 gal
          (It was assumed that inflow to holding
          tank was 85 percent  of outflow during
          the 30  minute period; i.e.,
    
          6000
            2~  x 0.85 = 2550  gallons).
    
        Total waste flow for 24-hour period (i.e., summation
          of above)  = 42,295 gallons.
    
    The total waste flow  corresponding  to  electroplating  and
    finishing  production  for  August  21,   was  determined  as
    follows:
    
        Hours of  waste treatment plant processing:
                                   210
    

    -------
                  TABLE 48        HOLDING TANK LEVELS AT THE START AND END
                                  OF THE WASTE TREATMENT PROCESSING
    	       PERIODS ON VARIOUS DAYS
    
                                         Alkali-Cyanide               Acid-Chromium
                                     Holding Tank Level(a),        Holding  Tank Level (b),
     Date             Time                  inches                      inches
    8/20/74
    
    8/21/74
    
    8/22/74
    
    8/23/74
    Start:
    End:
    Start:
    End:
    Start:
    End:
    Start:
    0815
    1530
    0845
    1530
    0845
    1530
    0845
    54.0
    12.0
    69.4
    33.5
    86.5
    38.7
    86.5
    42.0
    6.0
    36.0
    16.7
    46.0
    30.5
    52.5
    (a)   The  alkali-cyanide  holding  tank is  14.50  x  14.75  ft  so  that  1  inch  of  liquid
         level corresponds to  a  volume  of 133  gal.
    (b)   The  acid-chromium holding tank is 13.60 x 13.75 ft so that 1 inch of liquid
         level corresponds to  a  volume  of 117  gal.
                                         211
    

    -------
          0845 to  1530 = 6.75 hour.
        Average hourly effluent flow rate  (Table 33-20-8)
          = 5844 gph
        Total effluent flow during 6.75-hour period
          = 5844  (6.75) = 39,447 gallons
        Correction for change in level of holding
          tanks (Table 33-20-9)
            Alkali-CN level rise: 86.5 - 69.4 =
            +17.1 in; 17.1  (133) = + 2274 gallons
            Acid-Cr level rise: 46.0 - 36.0  = +10.0
            (1.17) = + 1170 gallons
        Total waste flow for 24-hour period (i.e.,
          summation of above) = 42,891 gallon
    
    Similarily,  the   total   waste   flow   corresponding   to
    electroplating  and  finishing production for August 22, was
    determined as follows:
    
        Hours of waste treatment plant processing:
          0845 to 1530 = 6.75 hr
        Average hourly effluent flow (Table 33-20-8)
          =6102 gph
        Total effluent flow during 6.75-hour period
          = 6102 (6.75)  = 41,189 gallon
        Corrections for changes in holding tank levels
          (Table 33-20-9)
          Alkali-CN tank level change:  no change in level
          Acid-Cr tank level rise: 52.5 - 46.5 = +6.5
            in; +6.5 (117)  = +760 gallons
        Total waste flow for 24-hr period (i.e., summation
          of above) = 41,949 gallons.
    
    The total waste flow values  as  determined  above  for  the
    three periods were as follows:
    
        1st period - 42,891 gallon
        2nd period - 41,949 gallon
        3rd period - 42,295 gallon
    
    These  values  were  used  to  calculate  the water use/area
    processed  factors  for  evaluating  plant  compliance  with
    guidelines.
    
    Area Plated^Data
    
    The  values  of  area  plated  for   the  various  lines were
    determined from production data on parts processed  supplied
    by plating room personnel and from areas of individual parts
    calculated from measurements made.
                                   212
    

    -------
    Summarized  data  on  the  part description, number of parts
    processed,  the  individual  part  areas,  the   number   of
    qualifying  operations,  total  processed area, etc., on the
    various lines are presented in Table  49.   Table  50  gives
    similar  data  for the two tin automatic rack plating lines.
    With the exception of the tin automatic rack plating  lines,
    all  the  rest of the lines are manually operated.  The area
    processed on each part was taken as the total area that  was
    rinsed on the part.
    
    The following is the total area processed data for Plant 33-
    20 on one day:
    
               Item                    Total Processed Area
    
    Combined Lines (Table 33-20-10)         7713 sq ft
    Tin Automatic Rack
      Lines (Table 33-20-11)                 1874 sq ft
    
                        TOTAL               9587 sq ft
    
    The  above  values  of  9587 sq ft was used to calculate the
    water use/area processed  factors  for  each  of  the  three
    sampling  periods  during  the  plant  visit.   Plant  33-20
    personnel indicated that plating production  the  other  two
    days  was  similar  to that done on the first day.  However,
    this figure is a little below normal due to  recent  reduced
    demand.
    
    SAMPLING AND ANALYSIS OF PLANT„36-1
    
    Introduction and Rationale for Sampling Plant_36-1
    
    Plant  36-1  is  an  example of a captive shop with cyanide,
    chromium,  copper,  nickel,   zinc,   aluminum,   and   iron
    contributing  to  the  pollution  of  the plant stream.  The
    electrochemical operations include  copper,  brass,  nickel,
    cadmium,  and zinc plating and aluminum anodizing.  Chromate
    conversion  coatings  are  applied  in  two  processes:  (1)
    following zinc plating, and (2) as preparation for painting.
    Bright   dipping   of   brass,  nickel  and  aluminum  in  a
    dichromate-sulfuric acid solution is a sizeable  contributor
    of  heavy  metals to the waste stream.  Soap from burnishing
    operations and metal stripping solutions is also carried  in
    the  waste  for  treatment.  The raw wastes are treated by a
    batch system using chemical methods with FeSOU-reduction  of
    chromium  and cyanide oxidation by C12.  Hexavalent chromium
    and cyanide concentrations are determined before  and  after
    treatment.  Treatment chemicals are added in excess  (50 ppm)
    to assure completion of the reactions.
                                    213
    

    -------
         TABLE  49
    SUMMARIZED DATA ON AREAS PROCESSED ON VARIOUS LINES ON AUGUST 20  1974
    Line
    Zinc rack
    (Br. Dip + Zn +
    Chromate)
    Zinc rack
    (Br. Dip + Zn +
    Chromate)
    Zinc barrel
    (Zn + Chromate)
    Zinc barrel
    (Zn + Chromate
    Cadmium barrel
    (Br Dip + Cd +
    Chromate)
    Copper barrel
    (Cu)
    Tin barrel (Sn)
    Nickel rack
    (Br Dip + Hi)
    Bright dip
    Wax dip
    "Hybrite" dip
    
    (a)
    Bright dip
    Bright dip(a)
    Bright dip and
    rack copper
    plate selected
    areas 'a)
    Part No.
    34203-970
    333049-2
    60441-7
    50333-4
    54333-2
    56508-1
    55322-7
    62019-1
    55704-1
    50363-1
    —
    
    —
    
    Part Name
    Bellows assembly
    Bellows assembly
    Dial shaft
    Pivot point
    Spring washer
    Piston disc
    Terminal
    Bellows assembly
    Valve seat
    Insulator
    3-way pilot
    valve sub-
    assembly
    Copper tube
    End cover
    Valve body and
    connection
    tube assembly
    Number of
    Parts
    Processed
    2,000
    300
    1,325
    32,236
    42,000
    33,200
    28,000
    661
    6,000
    113,000
    3,000
    
    25,500
    8,400
    3,200
    3,200
    Measured
    Area per
    Part,
    sq in.
    23.36
    6
    1
    0
    1
    1
    1
    26
    3
    1
    16
    
    7
    2
    65
    (Br.
    3
    (Cu
    .663
    .78
    .397
    .334
    .368
    .80
    .49
    .93
    .139
    .30
    
    .47
    .46
    .70
    Dip)
    .902
    plate)
    Combined Lines Total
    Total
    Number of Processed
    Qualifying Area(b),
    Operations sq ft
    3 973
    3 42
    2 33
    2 178
    3 1,167
    1 315
    1 350
    2 243
    1 164
    1 894
    1 340
    
    1 1,323
    1 144
    1 1,460
    1 87
    I 7,713
    (a)   The area processed  data  corresponds  to  the  aroduction on the various  lines for August  20,  1974.
         Kith Lha exception  01  the  last  four  operations  at  the bottom of  the table, the work was all
         done in the  one  shift  from 0645  to 15]5.  The last four operations were carried out on a 2-shift
         basis,  and  the processed areas  shown correspond to the total production for the 2 shifts.
    (b)   The total processed  area values  shown in  this column take  into account the number of qualifying
         operations  involved  lor  the particular  part.
                                               214
    

    -------
          TABLE  50
    SUMMARIZED DATA ON AREAS PROCESSED ON TWO TIN AUTOMATIC
    RACK PLATING LINES ON AUGUST 20, 1974(a)
    Part No.
    24203-975
    -982
    -985
    -620
    -515
    -976
    -802
    -527
    - 77
    -440
    -545
    -787
    - 21
    -785
    34007-174
    - 33
    -241
    34599-3
    — 1
    -161
    - 39
    322978-25
    321609-2
    35495-39
    34433-21
    34433-133
    320597-1
    36799-28
    Part Name
    Bellows Assembly
    Ditto
    ii
    n
    n
    ii
    n
    n
    M
    n
    ti
    n
    ii
    n
    Bellows Assembly
    Ditto
    n
    Bellows Assembly
    Ditto
    M
    n
    Bellows Assembly
    Bellows Assembly
    Bellows Assembly
    Bellows Assembly
    Bellows Assembly
    Bellows Assembly
    Bellows Assembly
    Number of
    Parts
    Processed
    2,035
    3,553
    1,995
    200
    148
    700
    15
    89
    84
    479
    857
    217
    99
    600
    194
    209
    205
    1,844
    800
    149
    125
    361
    148
    97
    325
    210
    600
    1,800
    Individual
    Part
    Area,
    sq in.
    10.08
    22.35
    15.92
    22.64
    26.44
    10.08
    37.00
    29.50
    22.64
    7.74
    10.66
    10.08
    17.70
    11.54
    24.70
    22.90
    9.50
    7.70
    9.66
    12.10
    18.20
    27.50
    14.52
    15.20
    10.95
    9.20
    23.50
    12.90
    Total Total Area
    Processed For Entire
    Area, Sub Group,
    sq ft sq ft
    142 1,221
    552
    221
    31
    27
    49
    4
    18
    13
    26
    63
    15
    12
    48
    33 80
    33
    14
    99 182
    54
    13
    16
    69 391
    15
    10
    25
    13
    98
    161
                                                     Combined Areas for Lines  1,874
    (a)   These  data  correspond  to  the  entire production of the two tin plating lines for
         August 20,  1974.  The  production was done on one shift from 0645 to 1515.  The
         number of qualifying operations on this line is one  (i.e., tin plating).
                                         215
    

    -------
    Sampling
    
    The  batch-type treatment system for plating wastes employed
    by Plant 36-1 dictates a different approach to sampling than
    the one applied to other  plants.   Where  in  normal  cases
    production  and  treatment  are  simultaneous and a constant
    effluent flow is  encountered,  the  batch  treatment  shows
    considerable  lag  time  from  production  to  treatment  to
    discharge.  Cyanide wastes, for example, are collected  over
    a 5 to 6-day period in the treatment tank, treated, and then
    discharged  after  settling  over  an 8-hour working period.
    The sampling data was,  therefore,  fixed  for  the  day  of
    cyanide discharge.  A raw waste cyanide sample was collected
    before  treatment  and  the treated cyanide was continuously
    sampled during the time of discharge.  Within the same  time
    period  a  treated  acid-alkali-chromium tank, was discharged
    and combined with the treated cyanide waste.   A  continuous
    sample  was  also  taken at this point.  Other treated acid-
    alkali-chromium  wastes,   originating   during   the   same
    production  period  as the cyanide wastes were also obtained
    from plant personnel.   These  samples  had  been  collected
    earlier  from a continuous sampler, collecting 35 ml every 9
    minutes.  Table 51 shows the collection rates used, and  the
    sampling  points  are  indicated on the treatment diagram of
    Figure 25.
    
    Effluent Discharge
    
    The time intervals  from  production  through  discharge  of
    effluent  are  shown  in  Table 52.  The effluent discharges
    achieved are shown in Table 53.  The treated cyanide stream,
    discharged during the day of the plant  visit  was  actually
    the result of filling over a period of 7 days almost 2 weeks
    earlier.   Reduction  of CN-concentration in the (automatic)
    zinc bath, reduction of water use, and a drop in  production
    have  limited  CN-waste  treatment  to  once a week.  Of the
    27,900 gallons treated, 25,850 gallons were discharged as  a
    combined   effluent  with  40,800  gallons  of  acid-alkali-
    chromium waste.  The balance of 2050 gallons  from  the  CN-
    waste  treatment  and  5440  gallons treated acid waste were
    transferred as 2 to 4 percent sludge to a holding tank  from
    where  it is hauled to a nearby company-owned landfill.  The
    effluent volume hauled away as liquid sludge  is  considered
    egual  to  the volume of liquid feed of treatment chemicals.
    Consequently, the plant water use is  equal  to  the  volume
    discharged.
    
    Cyanide  effluent  is never discharged by itself, but always
    in conjunction with one or  more  acid  tanks.   During  the
    sampling  period  the  combined effluent was 66,650 gallons.
                                   216
    

    -------
    I—,-
                R.F.
                      VATn
                     SVPPLY
              CHIC'!:::
             cw.r TAJ.-,.
          • A;:i5 A:"T'.^Tis.t
                                  o-
                                   PAW ACID ruy.rs
                                    CKLORIWTOR
                                  •o
                                                                 6 AC 10
                                                               Tp.r^ryEJ.T
                                                                 TA:.XS
                                                               5Q.CC3 CALS. EACH
                                                         Cii.-MCAL
                                                       j   iVWS
                                                                      	j  SIUOCE
                                                                       L_J£!L
                                                                  """   I>
    
    ,
    
    4 SL'JKI
    30.C.13 CMS.
    
                                  f-O
                                   Sl'.nCE
                                   n"x?s
                            2 CY.V:IDE
                          TREATX£NT TA7.TC3
                                 **
                                  3
                                                                                I
                                                    SLtliCt TU'CK
                                                                                              ^ RATE OF FLC'-/
                                                                                              C,) CONT'O'-L!*
                                                                                                   90 CW
                                                                                                «^TE or rtcw
                                                                                                 CONIRO'-LHl
                                                                                                   45 CPX
                                       PL-yj-S
                                    SLL'DCE   DIUV OFF
                                   TO R.SW    ACID LINE
                                                                                                                   STOW Sr-T
                                 FIGURE 25
    DIAGRAM FOR CYANIDE AND ACID WASTES TREATMENT
          *   Sampling point 1  is used  for sampling of acid effluents and  combined acid-cyanide  effluent.
         **   Raw waste was taken directly from tank after mixing of  the weekly  accumulated volume.
    

    -------
    TABLE  51      COLLECTION RATES AND VOLUMES  OF SAMPLING
                   July  31,  1974  -  Plant  36-1
    Time
    Composite 09:30
    09:45
    10:10
    13:40
    15:50
    
    Cyanide 09:30
    09:40
    09:50
    10:10
    13:40
    15:50
    
    ON TIME,
    sec
    37
    46
    49
    50
    Sampling
    
    59
    45
    46
    46
    48
    Sampling
    
    OFF TEME,
    sec
    235
    236
    234
    233
    Complete
    
    21:.
    254
    216
    216
    210
    Complet.e
    
    TOTAL TIME,
    sec
    272
    282
    283
    283
    
    
    270
    299
    262
    262
    258
    
    
    ml
    40
    47
    51
    51
    
    
    90
    64
    49
    49
    49
    
    
    ml/hr
    529
    600
    649
    649
    
    
    1200
    770
    673
    673
    684
    
    
    Total
    Volume , ml
    __
    132
    250
    2.271
    1406
    4059
    __
    200
    128
    224
    2355
    1482
    4389
                        218
    

    -------
                                                   TABLE   52     WASTE TREATMENT SCHEDULE AND WASTE VOLUME FOR THE
                                                                  PRODUCTION PERIOD FROM JULY 19 TO  JULY  25,  1974
    VO
    Discharge Sampling Rate
    Waste Stream
    Acid No. 4
    5,6
    1,2,3,5
    
    
    4,6
    
    2
    Cyanide No. 7
    1,3
    5
    6
    4
    1,2,3
    
    5
    6
    2
    4
    1.3
    5
    
    
    
    
    Cyanide No. 8
    
    
    Tank Filling
    7/18 to 7/19
    7/19
    7/19 to 7/22
    
    
    7/22
    
    7/23
    7/12 to 7/19
    7/23 to 7/24
    7/24
    > 7/24 to 7/25
    7/25 to 7/26
    
    7/26 to 7/27
    7/27 to 7/28
    7/28 to 7/29
    7/28
    7/29
    7/29 (15:00)
    to
    7/30 (06:00)
    7/30
    (10:30 to 12:30)
    7/19 (11:00)
    to
    7/26 (09:30)
    Tank Treated
    7/19
    7/19
    7/22
    
    
    7/23
    
    7/24
    7/19 to 7/23
    7/24
    7/25
    >7/25
    7/26
    
    7/28
    7/29
    7/29
    7/29
    7/29
    7/30
    (12:30 to 13:45)
    
    
    
    7/26 (09:30)
    to
    7/30 (10:45)
    Volume,
    Settling Tank Discharged gal
    7/19 #5
    7/19 #4,6
    7/22 n
    #1,3
    5
    7/23 #4
    #6
    7/24
    7/23 to 7/24
    7/24
    I""
    >7/2",
    7/26 02
    #3
    7/28
    7/29
    7/29
    7/29
    7/29
    7/30 (13:45)
    to (09
    7/31 (09:30)
    
    
    7/30 (10:45)
    to (09
    7/31 (09:30)
    7/19 42,160
    7/19 to7/22 89,530
    7/22 43,066
    »
    7/22 to 7/23 127,610
    7/23 to 7/24 41,253
    7/24 42,160
    7/24 43,293
    7/24 25,850
    7/24 to 7/25 85,000
    I 7/25 to 7/26 >85,453
    '7/26 40,800
    7/26 to 7/28 87,720
    7/28 43,520
    7/29 40,346
    
    • 7/29 to 7/30 122,622
    
    7/30 to 7/31 82,053
    7/31 40,800'
    :30 to 15:50)
    
    '66,65(
    
    7/31 25,850
    :30 to 15:50)
    
    Rate, Volume,
    gal/min ml/hr ml
    90 230
    24 230
    90 230
    
    133 230
    43 230
    175 230 ~
    175 230
    50 230
    90 230
    90 230
    90 230
    23 230
    90 230
    90 230
    
    128 230
    
    85 230
    107 } 529- 645 4060
    
    
    ) '175
    
    58 j 673-1200 4390
    
    
    

    -------
    TACLE  53     COMPARISON OF TREATMENT RESULTS WITH EFFLUENT GUIDELINE REQUIREMENTS FROM SAMPLING
                  PROGRAM ON PLANT 36-1 OPERATIONS
    166-1/2- Hour Period 
    -------
    discharged at a  rate  of  175  gal/min.   Acid  wastes  are
    discharged  irregularly, depending on need, varying from one
    to three combined tanks with a discharge rate from about  20
    to  175  gal/min,  depending on daylight, overnight, or over
    weekend  discharge.   Lowest  flow  rates  are  measured  on
    weekends and highest during daytime with normal production.
    
    Over  a 96-hour period 417,065 gallons  (1,578,591 1) of acid
    waste only  were  discharged,  while  for  a  weekly  period
    consisting  of  184  hours, 640,352 gallons (2,423,630 1)  of
    acid waste and 25,800 gallons  97,653  1)  for  a  total  of
    666,125 gallons (2,521,283 1) were discharged.
    
                        Re suits
    Analytical  data  show a raw waste concentration of 304 mg/1
    of cyanide.  After  treatment  by  chlorination  at  two  pH
    levels, the total cyanide concentration is 0.52 mg/1 showing
    that  the  cyanide  oxidation reaction goes 99.83 percent to
    completion.
    
    Similar data for hexavalent chromium reduction could not  be
    determined,  because a meaningful raw waste sample from Tank
    No. 5 or any previously  treated  chromium  wastes  was  not
    available.
    
    WaterUseandPrcess
    In  order  to  correlate  process  rates  and  water use for
    ultimate determination of  effluent  parameters   (mg/sq  m) ,
    water  use  was  calculated within definite time periods for
    which  plant  production  was  determined.   The  production
    schedule is summarized in Table 54.
    
    For one 8-hour period the water use was 252,270 liters.  The
    sq m processed are composed of the following operations:
    
        (1)  Chromate conversion  coating of 123 and 195
             sq m from C- shift on 7/29 , and A-shift on
             7/30 for a total of 318 sq m
    
        (2)  Bright dip production of 5029 and 6767
             sq m on 7/29 and 7/30 divided by 3
             to take into account a one-shift pro-
             duction on each day for a total of 3932 sq m
    
        (3)  Strand anodizing of 1541 sq m composed
             of 868 sq m on 7/29 and 673 sq m on 7/30
    
        (4)  Chromate conversion coating following zinc
                                  221
    

    -------
    NJ
                                       TABLE  54     SUMMARY OF PRODUCTION SCHEDULE FOR THE PERIOD FROM
                                                     JULY 19 TO JULY 30, 1974
    /Automatic
    Barrel Zinc
    Date
    7/19
    7/22
    7/23
    7/24
    7/25
    7/26
    7/29
    7/30
    7/19 to 7/26
    7/24 to 7/29
    sq m
    1669
    2523
    2673
    2973
    1205
    1744
    1490
    1126
    12787
    5926
    sq ft
    17966
    27156
    28778
    31994
    12972
    18776
    16036
    12120
    137642
    63781
    C&D Line Strand Nickel
    sq m
    495
    638
    533
    510
    554
    497
    522
    885
    3227
    182,8
    sq ft sq m sq ft
    5326 811 8732
    6867 643 6917
    5735
    5485
    5966
    5346
    5623
    9529
    34725 1454 15649
    19678
    Strand Anodizing
    sq m
    --
    --
    3994
    3702
    2138
    1738
    1736
    1354
    11572
    7453
    sq ft
    --
    --
    42992
    39846
    22022
    18708
    18574
    14570
    124568
    80227
    Total Electro-
    chem. Proc.
    sq rn
    2975
    3804
    7200
    7183
    3897
    3979
    3748
    3365
    29040
    15207
    sq ft
    32024
    40940
    77505
    77325
    41960
    42830
    40233
    36219
    312584
    163686
    C'nromate
    Processes
    sq m
    808
    931
    652
    764
    647
    970
    884
    780
    4772
    2868
    sq ft
    8700
    10020
    7020
    8220
    6960
    10440
    9360
    8400
    51360
    30870
    Bright Dip
    sq m
    12060
    6290
    5090
    4045
    1893
    5793
    5029
    6767
    35171
    14738
    sq ft
    129817
    6774
    54792
    43542
    20376
    62361
    54141
    72895
    378599
    158649
    Total
    Processes
    sq m
    15843
    11025
    12942
    11994
    6437
    10742
    9661
    10795
    68983
    32813
    sq ft
    170541
    118671
    139317
    129087
    69296
    115631
    103734
    117464
    742543
    353205
    

    -------
             plating, which is 1/2 of 1490 + 1126 = 1308 sq m
    
        (5)  Strand Nickel plating 352 sq m
    
    Totals  (1)   through  (5)  = 7442 sq m.  Because three tanks
    were filling simultaneously, only 1/3 or 2481 sq m  will  be
    applicable processed area.
    
        (6)  Miscellaneous barrel plating operations,
             called C&D line, consisting of copper,
             nickel, cadmium and brass plating.
             For the period from 7/19 to 7/26, 3277 sq m
             were processed, 1/4 of which was acid
             waste from the nickel plating,  (5) above,
             for a total of 2420 sq m.
    
        (7)  Cyanide barrel zinc plating from 7/19
             to 7/26 amounted to 12,787 sq m.
             Disallowing for the chromate coating following
             zinc plating, the actual area processed
             is 6393 sq m.
    
    Total  cyanide  production is then 8813 sq m.  When combined
    with the acid-lines, a total process rate  of  11,294  sq  m
     (121,572  sq  ft)  is  obtained.   The  calculated water use
    factor equals:
    
                  252^270 liters = 22.337 = 22.4 1/sq m.
                   "11,294 sq m
    
    This factor is considered applicable  whenever  cyanide  and
    acid  wastes  are  discharged  together.   In the above case,
    only one acid tank was combined with the   cyanide  tank,   so
    that  the cyanide concentration can be expected to be at its
    maximum  in  the  effluent,  assuming   consistent   cyanide
    destruction efficiency in the waste treatment.
    
    A  second type of effluent is being discharged from the plant
    on 5 out of every 6 days from wastes excluding cyanide.  The
    second  period   (96   hours)  in  Table   53  provides such  an
    effluent.  The concentrations given are   the  averages  from
    the analysis  of  four  samples collected continuously from
    7/26 to 7/31.  The total water  use  corresponding  to  this
    period  was 417,065 gallons  (1,578,591 1)  and coincides with
    the production period from 7/24 to  7/29   with   1/2  of  the
    production rate on 7/24.  The sq m processed are as follows:
    
         (1)  Chromate from zinc barrel line  for 2963 sq m
    
         (2)  Barrel  nickel from the C&D line  for 457 sq m
                                   223
    

    -------
         (3)  Strand anodizing processing 7453 sq m
    
         (4)  Chromate conversion coating prior to  painting  for
             2868 sq m
    
         (5)  Bright dip operations of 14,738 sq m.
    
    The total area processed is 28,479 sq m and  the  water  use
    factor is then:
    
             Ix518«.591_liter = 55.43 1/sq m
                28, 479 sq m
    
    This  factor  is  considerably  greater  than the other two,
    which can be attributed to the  fact  that  water  use  from
    burnishing  operations,  electrolytic alkali cleaning of 586
    sq m of wire, and the volume of water from cleaning and acid
    pickling prior to zinc plating are  included  in  the  total
    water  flow.   In  this  respect,  this  water use factor is
    likely to be a maximum for the plant operations.
    
    In order to calculate an average 30-day effluent  discharge,
    the   production  and  water  use  of  one  total  work-week
    including  both cyanide and acid effluents were  correlated.
    In  the  seven day period during which the cyanide treatment
    tank was filling, (Table 36-1-3), was taken to be the  norm.
    In  the  166-1/2-hour working period the total water use was
    2,038,457 1 (538,562 gallons]!  composed of 97,842  1  (25,800
    gallons)   of cyanide waste and 1,940,615 1 (512,712 gallons)
    of acid waste, including  water  from  burnishing  and  wire
    cleaning  operations for which an area value is not included
    in  the  total  area  processed  of  68,983   sq   m.    The
    corresponding water use factor is:
    
             2.038,457 1  = 29.6 l/m*
               68,983 sq m
    
    The  concentrations  in  the  effluent  are  weighted in the
    ratios of  acid  and  cyanide  wastes  from  the  analytical
    results  of  the  cyanide stream and the average of the acid
    streams of the 96-hour period.  The 30-day  average  should,
    therefore,  closely  agree with the discharge values of 166-
    1/2-hour period.
    
    Considering that the production of Plant 36-1 is compared of
    a  number  of  electrochemical   operations   (plating   and
    anodizing), and chemical operations (conversion coatings and
    bright  dipping),  as  well  as burnishing and wirecleaning,
    approximate water use factors for these  operations  may  be
    calculated.  Evaluations during a number of plant visits and
                                   224
    

    -------
    water  flow  measurements  indicate  that  approximately  45
    percent of the  water  is  being  used  for  electrochemical
    operations.   Taking  the  production  for  the 166-1/2-hour
    period from Table 54 and the water use for the  same  period
    from Table 52, one obtains a water use factor of
    
              2^038^457 i x 45
               29,040 x TOO  ~  = 31.6 1/sq m
    
    for  electrochemical  processes and 28.1 1/sq m for chemical
    operations.  Taking these units  as  separate  entities  and
    applying  it  to  any  of  the  concentrations  of the three
    periods show that the plant could meet guideline values were
    it to operate on  electrodeposition  or  chemical  finishing
    only.
    
    Operation§_and Area Processed
    
    The  nickel  finishing  operations  and  the  sq  m or sq ft
    processed are summarized in Table 54 for each day from  July
    19  to July 30.  The products consist of small stamped parts
    and continuous wire or wire coils.   Areas  of  small  parts
    were  calculated by plant personnel.  Shaped wire areas were
    calculated by measuring cross-sectional areas multiplied  by
    unit length.  In some instances, weights and listed specific
    gravities for common brass, nickel and aluminum were used to
    compute  processed  areas.   In  the  case  of  zinc  barrel
    plating, the process areas  shown  are  twice  that  of  the
    production  rate, taking into account the conversion coating
    step on the zinc plate.  In all other instances, process and
    production rates  are  equal.   Not  included  in  the  area
    calculations  are  burnishing  or  deburring  operations and
    electrolytic  wire  cleaning.   These  operations  are   not
    considered to be within the scope of the guideline, although
    the rinses contribute directly to the waste stream.
    
    Summary -^Plant 36-12
    
    Introduction
    
    The data represented in this section are representative of a
    captive  shop  dealing  in  a  specific product.  All wastes
    originate from electroplating and bright dipping  processes,
    and  include  silver, tin, copper, zinc, and nickel, as well
    as cyanide.  Figure 26 shows  the  schematic  of  the  total
    plant  layout and Figures 27 to 29 show the individual lines
    contributing waste and the subsequent waste treatment.   The
    electroplating  facilities consist of four production lines.
    Ampere capacities, amperes used, and  production  rates  are
    tabulated below.
                                   225
    

    -------
        LINE 1
     TIN-PLATING
     332,000 SQ. FT.
     PER MONTH
    ELECTROLYTIC
    TIN RECOVERY
               It
     ALKALI AND
     FLOOR SPILL
     COLLECTION
                              LINE 2
                            COPPER-TIN
                            PLATING
                            333,000 SQ. FT.
                            PER MONTH
                                                  LINES
     COPPER-TIN
     PLATING
     144,000 SQ. FT.
     PER MONTH
                                                                        LINE 4
    COPPER SILVER
    COPPER-BARREL
    PLATING
    1 20,000 SQ. FT.
    PER MONTH
                                                                                             LINES
    BARREL-TIN
    PLATING
    15,00080. FT.
    PER MONTH
                                                                                                                  LINE 6
     ACID-PICKLING
     205,000 SQ. FT.
     PER MONTH
                             TIN
                             TREATMENT
                             RESERVOIR
     ELECTROLYTIC
     SILVER
     RECOVERY
      SILVER
      TREATMENT
      RESERVOIR
    CYANIDE
    DESTRUCT
                                                                                NICKEL
                                                                                TREATMENT
                                                                                RESERVOIR
       COPPER
       TREATMENT
       RESERVOIR
                                                                                                                   ALL USED
                                                                                                                   ALKALINE
                                                                                                                   CLEANER
                          TALL ACIDIC RINSES
                            ACID
                            COLLECTION
                                               T ALL ALKALINE  STEAM RE-USE WATER
    pH ADJUSTMENT
       SETTLING
       TANK
      SLUDGE
      FILTER
    CLEANER
    NEUTRALIZATION
    (FROM DUMPS)
    FIGURE 26
    
    
    *  NOT IN OPERATION DURING PLANT VISIT
                SCHEMATIC OF WASTE TREATMENT -
                PLANT 36-12
                                                                        TO STORM SEWER
                                                                                                TO SANITARY
                                                                                                SEWER
                                                                             2 - 3 gpm
                                                                       TO SANITARY SEWER
    

    -------
                                                                                                                                       '2gpm
    r-o
    NJ
                                                                                                                                                                   TIN PLATING  TIN-PLATING
                                                                                                                                                                   CONTINUOUS STRIP
                                                                                                                                                                   I = 720 AMPERE AVG.
                                                                                                                                                                   COIL SPEED  19DR/HINAVG.
                                                                                                                                                                   PRODUCTION  133 MILLION PARTS
                                                                                                                                                                               PER MONTH
                                                                                                                                                                               = 332,000 SQ FT/MON.
                                                                                                                                                                   RATE        24 MRS/DAY
                                                                                                                                                                               7 DAYS/WEEK
                                                                                                                                                                               = 461 SOFT/MR
                                                                                                                                                                   EFFICIENCY, %   ~60
                         TO SANITARY
                         SEWER
                        F   (2-3 gpm)
                         (COMBINED)
                                                                                                  TO SANITARY
                                                                                                  SEWER
    
                                                                       FIGURE 27 SCHEMATIC OF TIN PLATING LINE AND WASTE TREATMENT
    

    -------
                                                                                                                                          COPPER - TIN PLATING
    
                                                                                                                                            CONTINUOUS STRIP
    ULTRA
    SONIC
    ALKALINE
    CLEAN
    ELECTRO-
    LYTIC
    CLEAN
    SPRAY
    RINSE
    RE USE
    WATER
        TO SANITARY
        SEWER
        (COMBINED)
    10%
    H2SO4
    COPPER
    TREAT
    SPRAY
    RINSE
    REUSE
    WATER
    COPPER
    PLATE
    COPPER
    TREAT
    SPRAY
    RINSE
    RE-USE
    WATER
                                                          RECRYST
                                                     DUMPS i
                                                                ACID
                                                                                                  TO SANITARY
                                                                                                  SEWER
                                                           FIGURE 28 SCHEMATIC OF TWO COPPER AND TIN PLATING
                                                                     LINES AND WASTE TREATMENT
    

    -------
    NICKEL
    TREAT
    NICKEL
    PLATE
    1%
    H2SO4
                                        i ALTERNATE
                                         PROCESS LINE
       COPPER - SILVER OR NICKEL PLATING
    
    CONTINUOUS STRIP
    I = 200 AMP. AVG
    COIL SPEED = 50 TO 140 FT/MIN SQM/MONTH
    PRODUCTION . Cu - Ag  100.000 SQM/MONTH
                Cu Ni    20,000 SOFT/MONTH
                16 MRS/DAY; 5 DAYS/WEEK
                                                                                                                     TO SANITARY
                                                                                                                     SEWER
                                                                                                                       (COMBINED)
    FIGURE 29 SCHEMATIC OF COPPER AND SILVER OR COPPER AND NICKEL PLATING LINE AND WASTE TREATMENT
    

    -------
    ELECTROPLATING LINES AT PLANT 36-12
    Line
    NO.
    1
    2
    
    3
    
    4
    
    
    Metal Product ion_Rate Amperes
    Plated ft2/hr
    Tin 461
    Copper, (2x) 461
    Tin
    Copper, (2x) 200
    Tin
    Copper, (2x) 340
    Silver,
    Tin
    m2/hr Capacity
    42.8 1,500
    42.8 2,000
    1,500
    18.6 500
    600
    31.6 500
    600
    1 ,000
    Use
    720
    220
    680
    140
    400
    
    220
    220
    Geometric Area
      Processed
              1,662
    135.8
                         237.7
    8,200
    2,580
             8,200
               2,580
    Geometric Area        2,462
    	Prgcessed^x^Q^ operations	
    
    WASTE WATER TREATMENT SYSTEM
    
    The  waste  treatment  is an integrated, continuous chemical
    one assisted by a preceding electrolytic recovery of  silver
    and tin.  Silver and tin are electrolytically recovered from
    a  concentrated, recirculating raw waste solution containing
    about 3 g/1 (0.1  oz/gal)  of  metal.   Integrated  chemical
    precipitation,  using  hydrazine  in  a  solution  of sodium
    carbonate and sodium  hydroxide,  takes  out  the  remaining
    traces  of  thse metals plus copper, zinc, and nickel.  Only
    one fresh rinse in each production line at the  end  of  the
    process  line  flowing  at  a  rate of 2 gpm account for the
    total water use of 480 gph.  A hot  deionized  rinse  before
    drying  is  regenerated  and not discharged.  The barrel tin
    and bright dipping process lines do not use any fresh water.
    
    The sludges from the treatment reservoirs are  collected  in
    the  sludge  filter  outside  the  building.   The  water is
    allowed to seep through  special  types  of  concrete  block
    widewalls  from  where  it is carried to the sanitary sewer.
    All acid-alkali rinses, floor spills, and overflows from the
    metal treatment reservoir  tanks  end  up  in  the  concrete
    settling  tank from where the sludges are pumped over to the
    sludge filter.  The clean water flows over  into  a  smaller
    tank  which  serves  as  a reservoir from where the water is
    recycled to the rinses.
                        230
    

    -------
                                            Date
    2.4
    23
    22
    O.I
    20
     1.9
     i.e
     I 7
     16
     I 5
     14
     1.3
     1.2
     I I
     10
    09
    08
    0.7
    06
    05
    04
    03
    02
    01
      0
     I 8
     1.7
     1.6
     15
     14
     13
     1.2
     I I
     1.0
    09
    0.8
    O7
    0.6
    05
    04
    0.3
    02
     O.I
      0
     16
     1.5
     14
     13
     1.2
      I I
     10
    09
    08
    07
    06
    05
    04
    0 3
    0.2
    01
      0
    TI   I  i   i  i
       June
                 .11
                 'i
                /i
                '  i
               '  i
         A
                  Bright Dip-**  ',
                             I   i
                             i   i
                             i   i
                             i   «
     ft                  t  «'   \
     j -^PPM Cu      ,' \/ '(    \
     i  •                 '  i\ '\     »
     .'  v               ' !\i\     *
    1     -    -       ;ji\     k
                                                          r*.   f- <£ 00 00 (£> fcT)
                                                                 CO 00 CO 00 GO
                                                                   PPM Cu
              01 f- r-
              00 CO CD
                        ODCOODODOOODCOCOCOCDCOaD
                                 rO  iO f^ *T> (J)
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    f
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                                                       PPM Cu
                     k /
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                              CO CO CD  CD
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    48
    4.6
    44
    4.2
    40
    38
    3.6
    3 4
    32
    30
    28
    :.e
    24
    22
    20
    i 8
    16
    I 4
    : 2
    iO
    OS
    06
    04
    02
    0
    3 6
    34
    32
    30
    28
    2.6
    2.4
    22
    20
    I 8
    i 6
     4
    I 2
    .0
    08
    06
    04
    02
    0
    T f
    30
    28
    26
    2 4
    2 2
    20
    18
    I 6
    I 4
    I 2
    I 0
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    06
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    0
         00000000 00 00 CD CO 00 00
                                 O   C7> CD CD
    
                                         PH
                                                                                     •o
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                                                                                     Q
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     FIGURF    30
                               FFFFCT OF RRTGTIT DIPPING ON
                               Cu AND  Zn CONCENTRATIONS  IN
                               EFFLUENT
                                             231
    

    -------
                                d>   V   6   0   10   «
    O
     -3   4-
                         FIGURE  31
    CHANGE OF AVERAGE EFFLUENT CONCENTRATION AND  pH
    

    -------
    The amount of bright dipping Of brass is believed  by  plant
    personnel to be responsible for the variations of copper and
    zinc  concentrations in the final effluent (Figure 30).  The
    treatment cycle  lags  about  24  hours  behind  bright  dip
    operation.   Figure  30  shows  the monthly average effluent
    concentration of copper  and  zinc.   Figure  31  shows  the
    monthly  average  concentrations  of copper and zinc and the
    change of pH in the effluent.  A direct correlation  between
    bright  dip  processing  or  pH for the amounts of copper or
    zinc discharged cannot be established.  All treatment cycles
    are  monitored  and  controlled  by  automatic  pH  and  ORP
    instruments.
    
    Calculation of Effluent Parameters
    
    Plant 36-12 shows a total water flow of 2160 gph to a stream
    and  400  gph  to the sanitary sewer.  Of the 2160 gph, only
    480 gph originate from four continuous strip plating  lines,
    one  barrel  plating  line, and one bright dip line.  On the
    average, 1460 sq ft of phosphor bronze and  cartridge  brass
    and  minor  amounts  of  steel  are electroplated and bright
    dipped per hour.  The average water use is
    
             480 gal
             	hr
            1460 ft£
                 hr
    
          = .329 gal/sq ft
    
          = 13.40 1/mz
    
    Summary - Plant.,33-5
    
    Introduction
    
    The data presented in this section show the efforts made  by
    a  captive  shop  towards  treatment  of  waste  waters from
    plating processes involving  lead,  tin,  fluoroborate,  and
    fluoride,  as  well as copper, nickel and alkaline, and acid
    wastes.
    
    Waste Treatment^Facilities
    
    All treatment is achieved by batch  chemical  precipitation,
    without  aid  of evaporators, reverse osmosis, ion exchange,
    or  any  other  form  of  waste   treatment.    All   wastes
    originating  from  the  plant  are  combined  in  one of two
    concrete tanks having a capacity  of  20,000  gallons  each.
    Treatment  consists simply of hydroxide precipitation for 15
                                     233
    

    -------
    to 30 minutes.  Settling time; is eight hours,  and  drainage
    takes  about  1  hour.   Each tank is drained once each day.
    The produced sludge of about 1,600 ftVyear is pumped  twice
    a year to adjacent company-owned land.
    
    Table  55  shows data for the waste concentration of treated
    and untreated effluent and the typical ppm of each waste  in
    the rinse stations.
    
    Table  56 shows analytical data from 1970 to 1972 indicating
    variations in the treatment  achieved.   The  data  are  for
    monthly  composite samples collected daily from each treated
    tank, mixed, and then shipped once  a  month  to  a  company
    laboratory for analysis.
    
    The  total  average  water flow for two automatic production
    lines plating 46.2 m*/hr  (497 ft*/hr) is 10,900 1/hr  (2,880
    gph)   for  an  average  water  use  of  235  1/m2 1/m2  (5.80
    gal/ft2).  Table 57 shows an average  effluent  composition.
    Figure 33-5-1 shows the plating plant layout and the nominal
    water  use  of  4,088  1/hr  (1,080 gph) which when properly
    maintained by plant personnel would reduce the discharge  by
    a  factor of 0.375.  All effluent limitations and production
    parameters are summarized in Table 57.
    
    Plant_15-3
    
    The production rates for all of the indicated plating   lines
    vary  and  are  less  than a 40 hour work week.  In order to
    make  comparisons  with  other  plants,  these  rates   were
    converted to a weekly volume:
    
        A- Silver-plating
    
           Water usage     365 gph = 1382 1/hr
    
                0.2083* x  365 gph = 76.0 gph
    
                                   = 288 1/hr
    
    *From supplemental calculations.
    
        B. Cadmium Plating
    
           Water usage     944 gph = 3573 1/hr
    
                0.3375  x  944 gph =319 gph
    
                                   = 1207 1/hr
                                    234
    

    -------
    Igpm 2gpm 2gpm
    »1 » 1 11
    T
    
    HOT
    RINSE
    
    
    
    RINSE
    
    
    
    Pb-Sn
    FLASH
    
    
    IUIT
    STA-
    TION
    
    •^^^^^^
    RINSE
    
    
    
    
    
    (jj
    Ln
    1 \ \
    LOAD & RACK AUTOMATIC PLATING MACHINE FOR PLATING \Pb-Sn-Cu
    
    
    
    
    
    
    UNLOAD ON BEARING MATERIAL (Pb25/Sn1/Ar74) JALLOY
    V
    V
    ^-s^
    
    
    12gpm
    A 6gpm
    
    
    
    
    
    
    
    
    
    
    
    -------
                                           TABLE  55
    ANALYSIS OF RAW AND TREATED WASTE
    CO
    OJ
    Waste Constituent
    Lead
    Tin
    Copper
    Nickel
    Fluoride
    Fluoborate*
    Chloride
    Suspended Solids
    Dissolved Solids
    PH
    Raw Waste
    Concentration
    mg/1
    98
    50
    4
    88
    134
    160
    
    180
    1720
    3.40
    Treated
    Effluent
    Concentration
    mg/1
    39
    20
    2
    36
    65
    160
    
    190
    1630
    7.70
    Acid Rinse
    Waste Waste Concentration
    Removal Discharge Percent of
    Percent kg/hr mg/1 Raw Waste
    39.8 6 6.1
    40.0 5 10.0
    50.0 1 25.0
    40.9
    48.5
    0
    860
    —
    —
    «-•«
           * Tentative values, based on a spectrographic determination of Boron in the sample.
    

    -------
              TABLE  56
    PLANT EFFLUENT QUALITY AND STANDARDS*
    Sample
    Date
    4/12/72
    3/24/72
    3/1/72
    1/3/72
    1/5/72
    11/23/71
    12/10/71
    10/26/71
    9/16/71
    6/22/71
    10/6/71
    7/12/71
    12/17/70
    Average
    Stream
    Standards
    Effluent
    Average Effluent Concentration, mg/1
    Pb
    7.0
    0.69
    0.29-
    0.12 •
    15.8 *
    0.05 .
    13.5 .
    4.5
    3.2
    6.2
    2.9
    10.3 .
    2.0
    5.12
    0.05
    
    0.05
    Sn
    4.0
    0.05
    0.05
    
    0.05
    0.01
    0.31
    0.05
    0.05
    1.2
    0.15
    2.6
    0.10
    0.718
    
    
    
    Cu
    0.2
    0.5
    0.10
    0.75
    0.50
    0.05
    0.25
    0.40
    0.15
    0.60
    0.45
    0.90
    0.35
    0.365
    2.0
    
    1.0
    Ni
    4.4
    3.1
    7.2
    5.2
    8.7
    5.9
    4.9
    1.8
    2.8
    10.9
    4.9
    5.4
    8.84
    5.70
    2.0
    
    1.0
    Fe F
    59
    0.04
    0.08
    
    0.40
    0.01
    3.9
    0.19
    0.66
    0.63
    0.21
    0.44
    0.26
    0.62 .-59
    1.0
    
    5.0 2.0
    pH
    7.4
    6.85
    6.9
    7.5
    
    
    
    
    7.25
    
    
    
    
    7.18
    5.5-9.0
    
    5-9
      Standards
    * The data are  for  monthly composite samples collected daily at the
      plant and shipped once  a month to a company laboratory for analysis,
                                  237
    

    -------
                                       TABLE  57
    EFFLUENT LIMITATIONS AND PLANT PARAMETERS
    N)
    U)
    CO
    Plant No. 33-5
    Water use 1/hr
    gal/hr
    kg/rn2
    lb/ft2
    Effluent volume I/year x 106
    gal/year x 10°
    Production hours/year*
    Mur. ber of plating operations
    Nu-ber of rinses
    Arc-a processed m^/hr
    ft2/hr
    ypste Constituent Pb Sn
    Average constituent
    Concentration mg/1 5.12 0.72
    Discharge g/hr 55.8 7.83
    Ib/hr 0.12 0.02
    Eg/m2 1,208 170
    lb/106 ft2 241 40
    
    10,900 (total to waste treatment)
    2,380
    236
    48
    1,970
    520
    7,200
    4
    8
    46.2
    497
    Cu Ni Fe F BF^** S.S.
    0.37 5.70 0.62 59 160 33
    3.98 62.3 6.76 643 1,744 360
    0.009 0.14 0.015 1.42 3.85 0.79
    87.3 1,345 146 13,920 37,749 7,786
    18 282 30 2,857 7,746 1,590
    
    
    
    
    
    
    
    D.S.
    .1.059
    11,543
    25.5
    249,850
    51,308
            *  Based on 50 work-weeks per year.
    
    
           **  From BMI analysis; all other values are riant 33-5 values.
    

    -------
           Water usage     631 gph = 2388 1/hr
    
                  0.30  x  631 gph = 189.3 gph
    
                                   =717 1/hr
    
    Total water flow for the three metals plated
    
                                   = 584 gph
    
                                   = 2210 1/hr
    
        D- Nickel Plating
    
           Water usage    1830 gph =6927 1/hr
    
                0.3375* x 1830 gph =618 gph
    
                                   = 2339 1/hr
    
    The total average water flow is 1202 gph = 4550 1/hr
    
      = 1202 gph x 2000 hrs/yr = 2,404,000 gal/yr
      = 9,099,140 1/yr.
    
    If all the rinses are running all at the same time, then the
    total water use would be  3770 gph =  14,270 1/hr
    
      = 3770 gph x 2000 hrs/yr = 7,540,000 gal/yr
      = 28,538,900 I/year.
    
    However, company data show a raw waste volume of 3000 gph
    
      = 11,355 1/hr = 3000 gph x 2000 hrs/yr = 6,000,000 gal/yr
    
      = 22,710,000 I/year.
    
    Area  processed average hourly production based on  a 40
    hour  week:
    
        A. Silver
    
           161 ft2 x  0.2083 = 33.5  ft*/hr
    
                            = 3. 12  m«/hr
    
        B. Cadmium
                                      239
    

    -------
           280 ftz x 0.3375 = 94.5 ftz/hr
    
                            = 8.78 mz/hr
    
        C.  Tin
    
           215 ftz x 0.30 = 64.5 ftz/hr
    
                          = 5.99 mz/hr.
    
    Total hourly production rate ~ 192.5 ftz/hr = 17.89 m2/hr
    
        HO hr/wk x 50 wks/yr = 2000 hrs/yr x 192.5 ftz/hr
    
        = 385,000 ftz/yr = 35,767 mz/yr.
    
        D-  NickelJPlating
    
           206 ftz/hr x 0.3375 = 69.5 ftz/hr
    
                               = iS.46 mz/hr.
    
    The total average area processed = 262 ftz/hr
    
                                     = 24.35 mz/hr.
    
    The total number of plating operations are:
    
                   A-C     12
    
                   A-D     18
    
    and the number of rinses are
    
                         Acid-Alkali    Metal
           Acid-Alkali   Integrated   Integrated  Total
    A-C
    A-D
    12
    20
    4
    4
    5
    5
    21
    29
    Three  of  the  above  rinses are following posttreatment of
    cadmium in a total flow of  201 gph x 0.3375 = 67.8 gph = 257
    1/hr.
    
    Effluent from the waste treatment system goes  to  the  east
    pond  to the west pond to the lake water pond, from where it
    goes to the streams.  Analyses from this point are used  for
    the  discharge parameter calculations.  This is precipitated
    by pH in the ponds, but is  not analyzed.
                                    240
    

    -------
    The production rate is 90 ftz/hr for each of  three  plating
    operations  in  the  Pb-Sn-Cu line for a total of 270 ftz/hr
    and 227 ft^/hr for one plating operation  in  the  Sn  line.
    The   associated  number  of  rinses  are  five  and  three,
    respectively.  These production rates are based on 48 second
    indexing of an automatic rack plater and  18  baskets  every
    two  minutes  (510 baskets per hour)  operating 70 percent of
    the time.   The  water  use  is  not  controlled  on  either
    production  line,  but  is  left  to  the need of individual
    operators by simply opening  faucets  on  each  water  line.
    This  procedure accounts for the discrepancy of actual water
    use (2,880 gph)  and proposed water use (1,080 gph).
    
    Water Use Per Area Plated
        A. Silver
        B. Cadmium
        C. Tin
    76_gal/hr _
    33.5 ft2/hr =2.27 gal/ ft*
    
    288 1/hr
    3.2 m2/hr = 92.3 1/m2
                          __
                       94.5 ft2/hr = 3.38 gal/ft*
                       J207_l/hr_
                       8.78 m2/hr = 137.5
    189_c[al/hr
    64.5 mz/hr = 2.93 gal/ft*
    
    717 1/hr
        D. Nickel
    5.99 m*/hr = 119.7 l/m*
    
    618_gal/hr.
    69.5 ft2/hr = 8.89 gal/ft*
    
    2339 1/hr
    6.46 m2/hr = 362.1 1/m*
                584_aal/hr                22!2_l/hr __
    Total A-C = 192 ft2/hr = 3.04 gal/ftz 17.89 m2/hr
    
              = 123.6 l/m2
                                            4551 1/hr
          A-D = 261.5 ft2/hr = 4.60 gal/ft2 24.35 mz/hr
    
              = 186.9 l/m2
                                   241
    

    -------
    Plant 20-24 is an  automatic  rack  plater  doing  chromium,
    copper  and copper alloys, lead and lead alloys, nickel, tin
    and tin alloys and zinc plating.
    
    Plant 20-24 employs a continuous treatment system  involving
    pH    adjustment,   precipitation   and   settling.     Also,
    evaporative recovery is employed  on  Cu,  Pb,  Sn.    Cr  is
    reduced  by metabisulfite and then precipitated.  Cyanide is
    recovered by evaporation.  Sludge  is  pumped  to  a  drying
    basin  and  subsequently  removed by a licensed hauler to an
    approved dump.  Effluent concentrations  achieved  by  plant
    20-24 are as follows:
    
                           mg/1
    
              Cu           0.17
              Pb           0.60
              Sn          <2.0
              Ni           1.9
              Cr           0.54
              Zn           0.25
              Cd          <0.01
              CN           0.02
              PO4          0.02
              F           11.0
              pH         8.5-9.5
              SS           4
    
    The  production  rate for 20-24 is 1200 sq ft/hr.  The plant
    operates 16 hr/day except for  one  line  which  operates  8
    hr/day.   The  total  effluent  flow  is  7000 gal/hr.  This
    corresponds to a water use of 5.8 gal/sq ft.
    
    Summary of 33-24
    
    Plant 33-24 does manual barrel plating of zinc and automatic
    rack plating of tin and tin alloys.  It employs a continuous
    treatment system involving pH adjustment, precipitation with
    hydrated lime and  clarification.   Hexavalent  chromium  is
    adjusted  to  a  pH  of <3 and reduced to trivalent chromium
    with sodium bisulfite,  cyanide is totally destroyed to  CO2
    and   N2  through  chlorination.   Sludge  is  hauled  to  a
    landfill.
    
    Effluent concentrations  achieved  by  plant  33-24  are  as
    follows:
    
                        mg/1
         Cu             <1.0
         Fe             < 1.0
                                    242
    

    -------
         Cr+3           <1.0
         Zn             <1.0
        *CN             <.025
        *Cr+«           <.05
         SS           <25
    
        *dissolved solids
    
    The  production  rate for 33-24 is 1300 sq ft/hr.  The plant
    operates 16 hrs/day, 5 days/week.  Total  effluent  flow  is
    4200  gal/hr.  This corresponds to a water use of 3.2 ^al/sq
    ft.
    
    SummarY_of_33-2
    
    Plant 33-2 is a manual rack and  barrel  plater  of  coppei
    cadmium,  gold, silver and rhodium.  Wastes from the platingN
    of Cu, Cd and Ag in cyanide solutions are  pumped  into  two
    100  gallon  lined tanks which are equipped with steam coils
    to  maintain  a  solution  temperature  of  205-210°  F.   A
    rectifier  is wired in series so that each tank is a plating
    tank.  The solution is plated out continuously.  Cu, Cd, and
    Ag plated out on the cathode are scraped into a lined barrel
    and sent out for reclaim.  No solution is ever discharged.
    
    Metal bearing acid wastes are collected into  a  non-flowing
    rinse  tank.  The tank is treated manually twice every eight
    hour shift.   Sodium  hydroxide  is  added  and  the  pH  is
    adjusted to 8.4-9.0.  The contents  then flow into a 100,000
    gallon  three stage sediment basin where metals precipitate.
    This basin is cleaned annually.
    
    A non-flowing tank  is also located  adjacent  to  each  gold
    plating  tank.   Here  the  pH is maintained at 4.4.  During
    non-working hours, gold is plated out  on  aluminum  cathode
    from which it is reclaimed.  The liquid is then discarded to
    the sediment basin after raising the pH to 8.5-9.0.
    
    The  rhodium rinse tank is also non-flowing.  The rinse tank
    is used until the metal concentration reaches 2 gm/gal.  The
    volume is then carbon treated  and  used  to  replenish  the
    rhodium solution.
    
    Effluent  concentrations  attained  by  plant  6-37  are  as
    follows:
    
                                 mg/1
            Au                   Trace
            Ag                   Trace
            CN                     .1
                                    243
    

    -------
            Rh
            pH
            TSS
          Trace
          5-10
           6
    The production rate for  33-2 is 30 sq ft/hr  of  gold/silver
    for  8 hr/day 5 days/week and 30 sq ft of rhodium/silver for
    1 hr/day  1 day/week.  The total effluent flow is  3333  gph.
    This corresponds to a water use of 111 gal/sq ft.
    
    Summary of_6-37
    
    Plant 6-37 is an automatic and manual rack plater of copper,
    nickel  and  silver.   It employs a batch electrolytic plate
    out for silver and copper and nickel go through closed  loop
    vacuum  distillation.  Cyanide is electrolytically destroyed
    followed by alkaline chlorination.  pH is adjusted  to   9.5
    with N2OH or lime,  sludge is dewatered and mixed with paper
    refuge   for  landfill   disposal.   Effluent  concentrations
    achieved by plant 6-37 are as follows:
           Ag
           CN
           Cu
           Ni
           pH
           DS
       mg/L
       <5
       <1
       <5
       <5
      7-10
      2760
    The production rate for 6-37 is 3080 sq ft/hr for 9 hr/day 5
    days/week.  The total effluent flow is  UOOO  gal/hr.   This
    corresponds to a water use of 1.3 gal/sq ft.
    
    Summ ary o f _ Pi ant _ 19_-11
    
    Plant  19-11  is  an  automatic  and  manual rack and barrel
    plater of gold, silver and rhodium.  It employs electrolytic
    recovery of gold and silver.  Rhodium passes through an  ion
    exchange  unit.  Cu is reduced by hydrazine and precipitated
    with the nickel.  Cyanide is alkaline  chlorinated.   pH  is
    adjusted  by  the  addition  of  Na^OH and H2SOJ*.  Sludge is
    disposed to municipal sewer beds.
    
    Effluent concentrations are as follows:
           Au
           Ag
           CN
           Rh
           Ni
    mg/1
     0
     0
     0
     0
                                 244
    

    -------
           Cu              <-5
           SS            <20.0
           pH            7.0-8.0
    
    Company._6::7
    
    Company 6-7 is a manual rack and barrel  plater  of  silver,
    copper  and  tin.   The  metal  waste  stream  is treated by
    adjusting the pH through addition of either acid  or  alkali
    stream  and then flowed into a settling tank.  Two-thirds of
    plating rinse water is recycled.  Sludge is  disposed  by  a
    licensed  contractor.   Effluent  concentrations achieved by
    plant 6-7 are as follows:
            Ag
            CN
            SS
            pH
      mg/1
      0.20
      0.12
      0.01
     25
    6.8-8.7
    The plant operates  16 hrs/day 5 days/week, except for silver
    line which operates 2  hrs/day.   The  total  flow  is  1920
    gal/hr.
    Plant   19-24  is  a plater of Cu, Cr, Ni, Cd, Pb, Sn, Ag and
    gold.    Metals   are    treated   by   neutralization    and
    precipitation  of  hydroxides with  lime.  Cr** is reduced to
    Cr*3 with sulfur dioxide and then precipitated,  cyanide  is
    batch  treated by a two-step oxidation process utilizing N2OH
    and  chlorine.   Finally,  the waste stream  is clarified and
    sand filtered.  Effluent concentrations  achieyed  by  this
    treatment system may be found below.
    
                              mg/1
            Cu                  .15
            Cr*6               <-03
            Cr*3               <.05
            Zn                 2.2
            F-                 2.2
            H                 <.0005
            Ag                  -05
            Cd                 <.02
    
    Summary of  20-17
    
    Plant   20-17 is   an  automatic  rack and  barrel  plater of  Ni,
    Zn,  Sn and  Sn alloys.   The treatment system  is  a  continuous
                                   245
    

    -------
     one  involving  neutralization  and clarification.   Sludge  is
     pumped to a drying lagoon or landfill.
    
     Effluent concentrations achieved  by  this   treatment   method
     may be found below:
    
                               mg/1
              Cd               .01
              Cu               .02
              Fe               .85
              Pb               .05*
              Ag              0*
              Ni               .31
              Cr               .06
              Zn               .17
              pH              7.18
              SS             20
    
             *grab
    
     Summary_Qf  Company 23^7
    
     Company  23-7  is  a  large  plater   of  Cu, Cr, Ni, Cd, and
     precious  metals.  The waste  treatment system is a continuous
     one.    The  waste  stream  is  treated  with  anti-foam  and
     coagulating agents before entering air mixing tank.  N2OH or
     H2SOU   is   added to maintain pH between 5.5 and 10.5. "After
     aeration  waste water flows to a series  of  settling  tanks.
     Excessive   concentrations  of  Cr+« are reduced with ferrous
     chloride.   Sludges are collected by a vendor and hauled to a
     landfill.   The  effluent  concentrations  achieved  by  this
     treatment system may be found below:
    
                                   mg/1
                Fe                  .5
                Al                 0.5
                Cr+*               5.0
                Cr+3               5.0
                Cu                  .01
                CN                  .01
                Cd                  .05
    
     Summary of  Plant 30-3
    
    Plant 30-3  is a small manual rack plater of gold,  silver and
    rhodium.     The    treatment   system   involves    alkaline
    precipitation of metals.  Cyanide is treated by N2OC1 and pH
    is adjusted by N2OH.   Sludge is disposed of by  a~ scavenger
    to an approved local  source.   The concentrations achieved by
    this system may be found below.
                                246
    

    -------
                                  mg/1
                Au                N.D.
                Ag                <0.01
                CN                 1.0
                Rh                N.D.
                pH                 8.3
                SS                31
    
    Summary of^30-21
    
    Company  30-21  is  a  manual  and  automatic rack plater of
    silver  and  gold.   Gold  is  treated  by  a   continuously
    operating  in  process  ion  exchange unit.  Silver is batch
    precipitated as a chloride.  Any basis metals added  to  the
    waste  stream  through  cleaning operations are precipitated
    with lime and ferric chloride and then filtered.  Cyanide is
    destroyed in a two step batch chlorine oxidation to CO2  and
    N2.   pH  is  adjusted  in the final effluent by lime slurry
    addition.   Sludge  is  pumped  to  impoundment   for   slow
    dewatering   and  land  disposal.   Effluent  concentrations
    achieved by this process may be found below:
    
                                 mg/1
                Au               .003*
                Ag               .03
                CN               .03-.1+
                P04             0.3+
                SS~            30
    
    *estimated
    +DS
     due largely to algal growth
    
    The production rate for plant 30-21 is approximately 1150 sq
    ft/hr.  The total flow is 35,000 gal/hr.   This  corresponds
    to a water use of 30 gal/sq ft.
    
    Waste Treatment Results
    
    Volume Capacity of Treatment Plant Studied.  Figure 27 shows
    the  volume capacity of the waste treatment plants for which
    data were received, as measured by the amount of waste water
    treated  per  hour.   The   range   of   capacities   covers
    approximately two orders of magnitude.
    
    The plot is a cumulative one indicating how many plants have
    a  water  use  less  than  the  volume  corresponding to the
    cummulative number.   Thus,  25  plants  have  a  volume  of
    100,000  liters/hour  or  less  and  4 plants have a greater
    volume.
                                  247
    

    -------
    PLANT
    
    *ll-8
    *33-20
    (+36-1
    
    (+36-12
    
    33-5
    115-3
    20-24
    
    33-24
    33-2
    
    115-1
    
    (12-6
    
    1133-15
    
    ff!2-3
    
    6-37
    
    43-1
    
    19-11
    
    6-7
    19-24
    20-17
    23-7
    30-21
    l/m2-op
    
    120
    176
    29
    
    13
    
    232
    184
    232
    
    128
    4440
    
    132
    
    60
    
    211
    
    80
    
    52
    
    -
    
    _
    
    _
    -
    -
    -
    _
    (gal/ft2-op)
    
    (3.0)
    (4.4)
    (.733)
    
    (.329)
    
    (5.8)
    (4.6)
    (5.8)
    
    (3-2)
    (111)
    
    (3.3)
    
    (1.5)
    
    (5.3)
    
    (2.0)
    
    (1.3)
    
    _
    
    _
    
    _
    -
    -
    -
    _
    Table 58
    mg/i
    Cu Ni CrT Cr+6 Zn Pb Sn cd Au *£ Rh
    
    .12 .60 .045 .03 .635 - - .21 - - -
    1.5* .09 .20 .10 .48* - .20 -03 - - -
    .14 .08 .06 .06 .34 - - .03 - - -
    f 01
    .73 - .52 - 0.5 - - <-01
    
    .365 5.7 - 5.12 .718 - - - -
    .26 .14 .07 .023 .12 - " •°09 "
    .17 1.9 .54 - .25 - - .01 - - -
    0
    <1.0 - <1.0 - <1.0 < .05 - " - " "
    Tr Tr Tr
    
    .-- - . 15 ------
    
    .8 .8 .4 .13 .3 - - - - - -
    
    .09 .27 .30 .28 - - - -
    
    .SO — .72 - .58 —
    c
    <5<5- - - -- - = --
    1 — — —
    .2 .5 .05 - - '3
    on o
    <.5- - - -- -00 U
    .20
    
    .15 - .05 .03 2.2 - - .02 - .05
    .02 .31 - - .17 .05 - .01 - 0
    .01 - 5.0 5.0 - - .05
    - .003 .03
    Al 32. CUT CNA
    .42 .41*
    
    .04 .04
    13 - .025 .014
    - < 01 -
    
    _
    
    .06 .06
    <.02
    .025°
    
    .1
    .16
    
    .14
    
    .01
    
    - - .11 -
    
    < 1
    
    .1 .001 .01
    
    - - 0 -
    
    - - .12 -
    
    - - -
    .06
    -
    .07°
    P04 F^ TSS gH
    .07 - < 10 6.0 -
    
    .13 - 10 8.2
    .02 - <10 6.0 -
    < 10 8.0
    
    59 - 7.18
    
    - - - 4.55
    .02 11 4 6.5 -
    < 25
    
    6 5 -
    - - - 6 -
    
    20.5 7.9-
    
    5.1 8.67
    
    - - - C -
    
    _ — — 7 —
    
    6.5 -
    
    20 7 -
    
    .01 - 25 6.8 -
    
    2.2 -
    20 7.18
    -
    .3° - 30 -
    
    9.5
    
    
    9.5
    
    
    
    
    
    9.5
    
    
    10
    10
    
    8.7
    
    
    
    9
    
    10
    
    8.0
    
    8
    
    8.7
    
    
    
    
    
    # = xn compliance w/ 1977 standards
    
    
    
    + = in compliance w/ new source performance standards
    
    
    
    * = out of compliance on parameters starred
    
    
    
    0 = dissolved solids
    

    -------
    Concentrations  of  Pollutants  and  Water  Use  Factors  in
    Plants.   The  concentration  of constituents in the treated
    effluent, the pH, and the water use factor for each  of  the
    previously  described  plants  are  shown  in Table 58.  The
    concentrations are for soluble plus  suspended  constituents
    in  the  effluent,  unless  otherwise  noted.  These results
    appear to have little relation to the type of  process  from
    which  waste  waters are derived with the possible exception
    of electroless plating.   The  complexing  agents,  such  as
    ammonia, that are dragged into waste waters from electroless
    plating baths are capable of inhibiting the precipitation of
    metals such as copper and nickel.
    
    Determination of Effluent Limitations
    
    Effluent limitations were established from three parameters:
    (1)  constituent  concentration  in  the effluent, (2) water
    use, and (3) area  processed  or  plated.   Some  dependence
    among  these  parameters  is  known,  i.e.,  coagulation  of
    precipitates out of dilute solution is more  difficult  than
    out  of  more concentrated solutions and area processed in a
    given line increases with complex shapes  that  give  higher
    dragout  and require more water for rinsing.  The plant data
    obtained show  no  evident  correlation  between  the  three
    factors   probably  because  variations  in  water  use  and
    concentration due to other factors mask out the relationship
    between the three factors mentioned.  Within the accuracy of
    the  information  available  the  three  factors   will   be
    considered independent, that is the concentration achievable
    in  the  effluent  by  exemplary  chemical  treatment is not
    related to the amount of water  used  for  processing.   The
    best water use is not necessarily found in a plant operating
    an  exemplary  waste  treatment  facility  and  vice  versa.
    However, once  exemplary  values  for  both  water  use  and
    concentrations  have been established the product of the two
    represents an  overall  figure  of  merit  that  takes  into
    account  both  parameters.  Therefore, the guidelines can be
    expressed in terms of the product  of  the  two  parameters:
    (mg/1)  x   (1/sq  m)  =  mg/sq m.  More water may be used if
    lower concentrations are achieved and vice versa.
    
    Concentrations of Effluent Constituents and	Eg.   Table  59
    lists  the  proposed concentration portion of the guidelines
    for each  parameter  to  be  limited.   It  also  shows  the
    fraction  of the fraction of analysis meeting these proposed
    concentrations.  The  values  proposed  are  for  the  total
    amount  of  constituent, dissolved or suspended.  Therefore,
    both proper precipitation and efficient clarification and/or
    filtration  are  required   to   meet   the   concentrations
    considered achievable.
                                  249
    

    -------
     TABLE 59 - Achievable Effluent Concentrations   (mg/1)
    
    
    
    
    
    
    TSS                             20
    
    
    
    Phosphorus                       1.0
    
    
    
    
    Cyanide  (oxidizablc)             0.05
    
    
    
    Cyanide  (total)                  0.5
    
    
    
    Fluoride                        20
    
    
    
    Cadmium                          0.3
    
    
    
    
    Chromium  (Hexavalent)            0.05
    
    
    
    Chromium  (total)                 0.5
    
    
    
    Copper                           0.5
    
    
    
    Iron                             1.0
    
    
    
    Lead                             0.5
    
    
    
    
    Nickel                          0.5
    
    
    
    Tin                             i.o
    
    
    
    Zinc                            0.5
    
    
    
    Platinum                        0.05
    
    
    
    Rhodium                         0.05
    
    
    
    Iridium                         0.05
    
    
    
    Osmium                          0.05
    
    
    
    Palladium                       0.05
    
    
    
    Ruthenium                       0.05
    
    
    
    
    pH                             6-9
                       250
    

    -------
    Figure  1  is a plot of water use values of 1/sq m-operation
    for fourteen plants.  Thirteen of these are  less  than  250
    1/sq  m-operation   (6.3  gal/sq  ft-operation) .   The median
    value is 125 1/sq  m-operation  (3.1  gal/sq  ft-operation).
    Because  the  influence of shape and design and the possible
    greater contributions made by  precious  metal  platers  the
    65th  percentile  of  160  1/sq  m-operation (U.O gal/sq ft-
    operation)  is chosen as the water use factor.
    
    Effluent Limitations Guidelines
    
    To derive guideline values, the water use factor of 160 1/sq
    in/operation is multiplied by the  concentrations  achievable
    by  coprecipitation  as  listed in Table 59.  This is the 30
    day average value.
    
    Recognizing that controls may not allow  attainment  of  the
    average  effluent limitation guidelines on a daily basis due
    to variation in  both  water  flow  and  concentration,  the
    maximum  for  any  single-day average is specified to be two
    times the 30-day average.
    
    Five months of daily data were  obtained  from  plant  15-1.
    This  data appears in Table 60.  In this time period the 30-
    day average value of 80 mg/m2 operation for Zn was  exceeded
    on  two  occasions,  December 4, 1971 and December 10, 1974.
    The thirty day average of 80 mg/m2 - operation for  CNT  was
    never   exceeded.   The  one-day  maximum  of  160  mg/m2
    operation was never exceeded by Zn or CN.
    
    One month1s effluent data was chosen at  random  from  plant
    12-6.  It appears in Table 61.  Ni, TSS, Cu, Zn, CNT are not
    out  of  compliance  with  the thirty day average or one-day
    maximum.  Cr+* is not out  of  compliance  with  the  30-day
    average but i s out on the one-day maximum three times during
    the month.
    
    Five months of twice weekly sampling TSS, for plant 33-15 is
    shown  in  Table  62.   CrT,  Ni, Cu never exceed the 30-day
    average or one-day maximum.  Cr+* is not in  compliance  for
    30-day average or one day maximum.
    
    Plants Meeting the Guidelines
    
    The  effluent concentrations and water use factors have been
    collected for 21 plants in Table 58.  Except as indicated on
    the table,  all values are in total solids.  Plants 36-1, 36-
    12, 15-3, 15-1, 12-6, 33-15 and 12-8 met the 1977 standards.
    Plants  36-1  and  36-12  met  the  new  source  performance
                                   251
    

    -------
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    -------
                           TABLE  60
                           PLANT  12-6
                                             mg/m2-0peratlon
    
     DATE                     pH             Zn           CNT
    11-13-7^                   8             1.3         27.7
    11-14-74                   7            11.9         14.5
    ll_l8-7U                   6            15.8         18.5
    11-19-74                   7            13.2         22.4
    11-20-74                   7            48.8         14.5
    11-25-711                   8            15.8         29.0
    11-26-74                  10             6.6         31.7
    
     Average                 7.6            17-4         23.3
    
    12-02-74                   8            10.6         30.4
    12-03-74                   7            14.5         46.2
    12-04-74                   7            12.1         29.0
    12-05-74                   6            55.4         17.2
    12-06-74                   6            17.2         21.1
    12-09-74                   9            15.8         31.7
    12-10-74                   9            92.4         23.8
    12-11-74                   7            29.0         21.1
    12-12-74                  10             5-3         23.8
    12-13-74                   8            37.0         37.0
    12-16-74                   8            01.1         22.4
    12-18-74                   7             9.2         19.8
    12-19-74                   7            25.1         17.2
    
     Average                 7.6            38.4         26.2
    
     1-03-75                   6            10.6         23.8
     1-06-75                   9            11.9         15.8
     1-07-75                   7             6.6         19.8
     1-08-75                   7             7.9         13.5
     1-09-75                   7            33.0         15.3
     1-10-75                   8            66.0         18.5
     1-13-75                   8            13.2         29.0
     1-14-75                  10            11.9         52.8
     1-15-75                   8            15.8         27.7
     1-16-75                   7            13.2         14.5
     1-17-75                   7            48.8         13.2
     1-20-75                   6            15.8         18.5
     1-22-75                   8             6.6         15.8
     1-23-75                   7             6.6         15.8
     1-24-75                   8            38.3         22.4
     1-27-75                   8             9.2         17.2
     1-28-75                   6             7.9         18.5
     1-29-75                   7             1.3         14.5
     1-30-75                   7            26.4         29.0
     1-31-75                 	7            21.1         26.4
    
     Average                 7.4            18.6         20.9
                               253
    

    -------
    DATE
    7-03-74
    7-09-74
    7-11-74
    7-15-74
    7-17-74
    7-23-74
    7-26-74
    7-30-74
    Average
    8-02-74
    8-06-74
    8-09-74
    8-12-74
    8-14-74
    8-19-74
    8-23-74
    8-26-74
    8-28-74
    Average
    9-04-74
    9-06-74
    9-10-74
    9-12-74
    9-16-74
    9-19-74
    9-24-74
    9-27-74
    Average
    10-02-74
    10-04-74
    10-07-74
    10-10-74
    10-15-74
    10-18-74
    10-21-74
    10-23-74
    10-29-74
    10-31-74
    Average
    11-04-74
    11-06-74
    11-12-74
    11-15-74
    11-19-74
    11-21-74
    11-25-74
    11-27-74
    7-5
    8.6
    8.8
    8.6
    8.3
    8.4
    8.4
    8.5
    8.4
    8.7
    8.5
    8.8
    8.9
    8.7
    8.5
    8.8
    8.6
    8.5
    8.7
    8.8
    8.8
    8.6
    8.7
    8.7
    8.8
    8.9
    9.1
    8.8
    8.9
    8.9
    8.7
    9.0
    8.6
    8.6
    8.9
    8.9
    8.9
    9.0
    8.8
    8.7
    8.3
    8.3
    8.7
    8.5
    8.6
    8.3
    8.7
    Average
    3.5
    
    TABLE
    PIANT
    61
    33 - 15
    
    
    
    mg/m2-0perat ion
    Cu
    18.5
    29.3
    16.2
    11.6
    31.7
    17-5
    16.3
    30.6
    21.5
    16.3
    10.2
    14.3
    11.0
    16.3
    19-7
    16.2
    48.2
    23.2
    21.9
    18.3
    28.6
    21.9
    19.7
    15.3
    13.9
    15.3
    30.2
    20.4
    24.1
    18.6
    30.6
    16.2
    18.5
    17.5
    36.7
    21.9
    26.3
    32.8
    30.4
    18.4
    24.5
    26.5
    22.4
    20.2
    34.9
    35.0
    17.2
    24.9
    Ni
    95
    34.3
    37-1
    44.1
    95
    35
    36.7
    49.0
    53-3
    42.8
    49.0
    40.8
    44.2
    57.1
    39.4
    51.0
    122.6
    74.2
    65.1
    89.7
    65.3
    21.9
    55.7
    7S.8
    46.4
    37.2
    74.2
    5E.6
    4-,. 8
    37.1
    96.4
    4t .1
    89.8
    87.6
    7-1.4
    65-7
    63.3
    48.2
    80.9
    40.8
    81.6
    73.4
    57.1
    71.8
    33.1
    8:..o
    55-0
    6:.. 7
    Cr+6
    89.8
    39.6
    46.4
    23.2
    52.8
    61.3
    53.0
    65.3
    53.9
    75.5
    65.3
    55.1
    25.8
    61.2
    46.0
    71-9
    74.5
    69.6
    68.1
    75.5
    36.7
    32.9
    50.8
    61.3
    69.6
    37.4
    60.3
    53-1
    50.4
    32.5
    21.9
    32.5
    23.7
    24.1
    20.4
    15-3
    6.6
    11.0
    29.3
    18.4
    30.6
    4.1
    53.0
    7.4
    25.8
    9.2
    24.1
    21.6
    CrT
    95
    44.9
    48.7
    27.8
    55.4
    63.5
    61.2
    71.4
    58.5
    77.5
    73.4
    61.2
    27.6
    63.2
    70.1
    81.2
    48.2
    83.5
    73.2
    77-5
    63.2
    54.8
    55.7
    63.5
    83.5
    59.1
    65.0
    65-3
    65.7
    39.^
    21.9
    32.5
    23-7
    26.3
    24. "S
    19.7
    11.0
    30.7
    36.9
    24 . 5
    34.7
    14.3
    75.5
    117.8
    42.3
    31.3
    46.4
    48.4
    CNT
    10.6
    2.9
    3.2
    2.8
    2.6
    8.7
    4.9
    4.1
    5.0
    6.7
    2.2
    5.3
    1.8
    2.0
    2.0
    3-0
    2.6
    2.1
    3-5
    8.2
    4.1
    8.1
    13.2
    8.1
    4.9
    3.7
    6.5
    7-1
    7.9
    7.9
    7.7
    4.9
    3.4
    8.3
    8.8
    13.8
    8.5
    8.1
    9.9
    5.1
    4.3
    - .2
    6.9
    2.4
    8.8
    2.4
    3.3
    4.3
    TSS
    845
    1637
    858
    766
    1109
    1226
    734
    877
    1006
    653
    714
    898
    2594
    1102
    1489
    974
    1862
    766
    1382
    836
    714
    701
    1067
    460
    742
    548
    928
    750
    1621
    742
    1051
    557
    818
    635
    612
    701
    876
    1007
    883
    449
    1204
    1775
    1408
    1398
    626
    3864
    877
    1450
                                         254
    

    -------
                         TABLE
                                 62
                         PLANT  15-1
                                                       mg/m2-0peration
    DATE
    
    6-01-74
    6-02-74
    6-03-74
    6-04-74
    6-05-74
    6-06-74
    6-07-74
    6-08-74
    6-09-74
    6-10-74
    6-11-74
    6-12-74
    6-13-74
    6-14-74
    6-15-74
    6-16-74
    6-17-74
    6-18-74
    6-19-74
    6-20-74
    6-21-74
    6-22-74
    6-23-74
    6-24-74
    6-25-74
    6-26-74
    6-27-74
    6-28-74
    6-29-74
    6-20-74
    pH
    Hi
    9.3
    8.6
    8.4
    8.6
    8.1
    8.1
    8.7
    9.5
    8.2
    9.0
    7.9
    8.0
    8.6
    8.9
    9.0
    8.6
    8.1
    8.2
    8.5
    9.1
    8.3
    9.5
    7.9
    8.9
    8.8
    8.9
    9.6
    9.8
    9.5
    8.1
    
    Lo
    7.5
    6.9
    6.9
    6.3
    6.6
    6.8
    7.8
    8.0
    6.8
    7.1
    6.6
    6.4
    7.4
    6.4
    7.5
    7.2
    6.9
    6.6
    7.3
    7-3
    7.5
    8.3
    6.6
    7.3
    7.2
    7.6
    7.8
    8.0
    8.3
    7.0
    CN
    
    5.7
    7.4
    5.3
    6.2
    6.6
    7.2
    10.6
    16.6
    35.3
    22.3
    19.2
    7.0
    6.6
    10.1
    6.2
    7.0
    5.7
    5.7
    6.2
    5-7
    6.6
    8.4
    7.4
    5.7
    6.2
    6.2
    6.2
    5.7
    5.7
    3.1
    Cr+6
    
    .52
    5.4
    .48
    2.2
    1.8
    1.3
    4.8
    .52
    4.2
    .62
    .60
    1.3
    .60
    .92
    .56
    1.3
    1.0
    1.0
    2.8
    8.3
    8.4
    40.3
    46.2
    .52
    5.6
    2.2
    1.7
    7-6
    78.0
    .28
    CrT
    
    5.2
    6.8
    4.8
    5.6
    6.0
    6.5
    9.6
    5.2
    6.0
    .72
    6.0
    6.4
    6.0
    9.2
    5.6
    6.4
    5.2
    5.2
    5.6
    10.4
    30.0
    15.2
    170.
    10.4
    16.8
    5.6
    5.6
    6.8
    130.
    22.4
    Zn
    
    5.2
    12.6
    19.2
    11.2
    12.0
    19-5
    28.8
    5.2
    12.0
    7.2
    12.0
    19.2
    24.0
    36.8
    16.8
    12.8
    5.2
    10.4
    11.2
    20.8
    12.0
    15.0
    20.4
    10.4
    5.6
    16.8
    11.2
    15.6
    15.6
    11.2
    Cu
    
    5.2
    20.4
    48
    44.8
    48.0
    58.5
    67.2
    31.2
    42.0
    50.4
    48.0
    57.6
    60
    73.0
    39.2
    38.0
    41.0
    36.4
    44.8
    41.6
    42.0
    22.8
    61.2
    52.
    50.4
    50.4
    33.6
    52.0
    57.2
    19.6
    Ni
    
    15.6
    13.6
    38.4
    56.0
    60.0
    84.5
    96.0
    20.8
    42.0
    21.6
    36.0
    57.6
    66.0
    110.4
    56.0
    25.6
    46.8
    36.4
    67.2
    31.2
    66.0
    30.4
    61.2
    41.6
    56.0
    44.8
    39.2
    31.2
    20.8
    8.4
    TSS
    
    1508
    408
    696
    476
    930
    813
    3984
    2392
    690
    806
    360
    536
    1560
    3588
    1736
    832
    416
    806
    308
    1196
    810
    2546
    1156
    1378
    1316
    980
    644
    1040
    1950
    794
    Average
    .7
    7.2
                  8.6
    8.0
    22.4    16.2    44.6
    46.0
                                              1170
                           255
    

    -------
    standards.   Plants 11-8 and 33-20 were out of compliance on
    only one or two parameters.
    
    Engineering Aspects of the Application of Various  Types  of
    Control Technology
    
    Advanced   in-process   controls  for  recovery  of  plating
    chemicals are rapidly gaining acceptance and  often  show  a
    net  cost  savings compared to chemical treatment.  However,
    the applicability of these in-process controls is  dependent
    on  first  achieving  reduction  in  water  use by multitank
    countercurrent rinsing.  Such installation is not  practical
    in all cases.
    
    Process Changes
    
    Process   changes   are  not  currently  available  for  the
    electroplating industry that would lead to greater pollution
    reduction than can be achieved by the  recommended  effluent
    limitations.   Some  possible process changes such as use of
    noncyanide  plating  baths  may  eliminate   one   pollution
    parameter,  but  do  not  eliminate  all and may cause other
    problems.   They  may  be  useful  in  some  facilities  for
    reducing  the  cost  of  meeting  the  effluent  limitations
    recommended in this document.
    
    Nonwater Quality Environmental Impact
    
    As discussed in Section VIII of this report,  the  principal
    nonwater quality aspect of electroplating waste treatment is
    in  the  area  of solid waste disposal.  Disposal of sludges
    resulting from metal removal  by  chemical  treatment  is  a
    current   problem   in   many   states   that  have  a  high
    concentration of facilities.  The problem might be partially
    alleviated by disposal of drier sludge.
    
    The use of advanced  technology  to  recover  metal  plating
    chemicals  from  rinse  water rather than chemical treatment
    which adds to the sludge is being applied in areas where the
    sludge-disposal problem is greatest.  Further impetus in the
    direction of recovery rather than disposal is expected to be
    provided  by  authorities  responsible   for   solid   waste
    disposal.   This  will  have an overall beneficial effect on
    water pollution because of the concurrent  requirements  for
    water  conservation  for  economic  application  of recovery
    techniques.
    
    It is estimated that  many  of  the  existing  sources  dis-
    charging  to  navigable  waters  are  already using chemical
    treatment methods with a high percentage removal of  metals.
                                   256
    

    -------
    This  is  particularly  true in geographic areas where water
    pollution reduction has  been  emphasized  and  the  sludge-
    disposal problem is most evident.
    
    There will be no direct effect on air quality as a result of
    the   application   of   recommended  technology  for  water
    pollution reduction.  Indirect effects related to  increased
    energy use are estimated to be modest.
    
    Guidelines ,for the^Application of^Effluent_Limitations
    
    Selection of Production Unit
    
    Effluent  limitations  are  intended  to specify the maximum
    quantity  of  pollutants  which  may  be  contained  in  the
    discharged  treated  effluent  from  a  point  source.  This
    quantity must be related to a unit of production so that the
    effluent limitations  can  be  applied  broadly  to  various
    plants  in  the same category regardless of their production
    capacity.   For  example,  an  effluent  limitation  for   a
    particular  wastewater  constituent  in  mg/unit  times  the
    production rate in units/hr equals  the  maximum  amount  of
    that constituent that can be discharged in mg/hr.  Thus, for
    any production unit:
    
          	ma  X  Unit   =   mg  X  1_
          unit      hr        1      hr        Equation 1
    
    The  right-hand  side  of  the above equation represents the
    normal  method  of   monitoring   based   on   analysis   of
    concentration  of  individual  pollutants in the effluent in
    mg/1 and measurement of the effluent discharge rate in 1/hr.
    Expressing the  effluent  limitation  as  a  function  of  a
    production  unit  compensates for change in production rate,
    which changes the effluent  discharge  rate.   The  effluent
    rate  in  the  electroplating industry is closely related to
    the rinse water  rate  which  is  in  turn  related  to  the
    production rate of electroplated parts.
    
    The  effluent  discharge  rate as volume per day is commonly
    reported by electroplating  and  other  industrial  sources.
    Because  many  plants  do not work on a 24-hour-day basis at
    all times, it would be preferable to use  the  next  smaller
    unit of time, which is an hour.  This avoids the uncertainty
    associated  with the daily unit which often requires further
    definition as to the number of shifts worked per day and the
    hours per shift.
    
    The most appropriate production unit in some  industries  is
    the  weight  of  product  produced  or  the  weight  of  raw
                                   257
    

    -------
     materials  purchased.  Neither a  unit  quantity  of  product
     produced   nor  a  unit  quantity  of  raw  material  use  is
     appropriate for the  electroplating  industry,  because  the
     quantity   of  product  expressed  as  the weight of products
     plated does not bear any relation  to  raw  waste  produced.
     Electroplating  is  a surface process that is not invluenced
     by the volume or density of the part plated.  The raw  waste
     load   is   related   to   surface   area  (not  volume)  of
     electroplated  parts  which  determines   the   concentrated
     solution dragout, rinse water use, and ultimately the degree
     of  pollution  reduction  achievable.  While it is common in
     barrel plating of small parts to weigh the plated parts as a
     control measure for basket loading, the  optimum  weight  of
     parts  was  originally determined by trial and error plating
     or precalculation of the part per unit weight  in  order  to
     achieve  the  correct total area.for optimum plating current
     density.   Regardless  of  the  method  of  controlling  the
     plating  operation, the dragout is related to the total area
     of parts plated and not the weight.   Solution  adhering  to
     the  surface  of  small parts causes dragout.  Although some
     cup-shape parts that are difficult to  drain  or  rinse  may
     cause  high  dragout  not  directly  related to area, weight
     would not be a good unit quantity applicable  to  both  rack
     and barrel plating.
    
     Although  the  amount  of  raw  material  used  or chemicals
     purchased was considered as a possible unit quantity related
     to production, neither unit appeared suitable as a  reliable
     measure of production.  The weight of material purchased and
     used as soluble anodes ends up on the parts plated, but this
    weight  must  be divided by the thickness plated to obtain a
     correlation with production rate in  area  plated  per  unit
     time  which  is  the true determinant of raw waste load.  In
     the case  of  chemicals  purchased  for  bath  make  up  and
     particularly  for  chromium salts purchased for plating with
     insoluble  anodes,  there  is  a  further  complication.   A
    material  balance  will show that the difference between the
     chromium purchased and the  chromium  on  the  plated  parts
     produced  equals  the  chromium  in  the precipitated sludge
    minus the small  amount  of  chromium  discharged  with  the
     treated   effluent.    Thus,   chromium  in  chromium  salts
    purchased in excess of that on plated parts reflects dragout
    and increased sludge but  not  necessarily  increased  water
    pollution.    The  same reasoning applies to all other metal-
    containing  chemicals  purchased  for  bath  make  up  which
    primarily  end  up  as  precipitated  and  separated sludge.
    Although the amount of chemicals purchased  indicates  total
    dissolved  salts  in  the  treated effluent,  total dissolved
     solids is not considered an important pollutant parameter in
    the electroplating industry.  (See Section VT.)
                                  258
    

    -------
    Consideration of the above factors  led  to  the  conclusion
    that   the   unit  of  production  most  applicable  to  the
    electroplating industry is surface area.  The  surface  area
    withdrawn   from   a  concentrated  solution  in  a  plating
    operation is the paramount  factor  influencing  dragout  of
    solution  constituents, some portion of which ends up in the
    waste water and treated effluent.  Surface area  influencing
    dragout  includes  not  only  the  surface area receiving an
    electroplate but also the  surface  area  of  nonsignificant
    surfaces  receiving  little  or  no  electrodeposit plus the
    surface area of racks or barrels which hold the parts.
    
    The total surface area is rarely known  and  impractical  to
    measure  in  some  cases in the electroplating industry.  In
    this case, the plated area is the alternative  logical  unit
    of  production.   However,  plated area is not a measurement
    that has been historically recorded by the industry and  may
    not be readily available from all plants.  Alternative units
    of production based on amperes and water use, which are more
    easily  measured,  were developed and correlated with plated
    area  and  ultimately  to  the   total   surface   area   in
    establishing  effluent limitations.  These alternative means
    of calculating the area plated should only be used until the
    industry does have ample records of area plated.
    
    Plated Area Unit of Production
    
    The plated area is the primary unit of production  on  which
    the  effluent limitations in Table 1 are based.  Plated area
    is defined with reference to Faraday1s Law  of  electrolysis
    by the following equation:
    
                       _EIT	
                   S = 100 kt                   Equation 2
    
    where s = area, sq m (sq ft)
    E = cathode current efficiency, percent
    I = current used, amperes
    T = time, hours
    t = average thickness of deposit, mm (mil)
    k = a constant for each metal plated based on the electro-
        chemical equivalent for metal deposition, amp-hr/mm-sq m
        (amp-hr/mil-sq ft).
    
    The  numerical product of current and time (IT) is the value
    that would be measured by an ampere-hour meter.   Values  of
    the constant k based on equivalent weight and the valance of
    the metal deposited are shown in Table 63.
                                    259
    

    -------
                                   TABLE 63  ELECTROCHEMICAL EQJIVALENTS AND RELATED DATA*
                               (All figures In this table are based on 100% current efficiency)
    Element
    Aluminum
    Antimony
    Arsenic
    Bismuth
    Cadmium
    Chromium
    Cobalt
    Copper
    Gallium
    Germanium
    Gold
    Indium
    Iridium
    Iron
    Lead
    Manganese
    Mercury
    Nickel
    Palladium
    Platinum
    Polonium
    Rhodium
    Rhenium
    Selenium
    Silver
    Tellurium
    Thallium
    Tin
    Zinc
    Atomic
    weight
    26.97
    121.76
    74.91
    209.0
    112.4
    52.01
    58.94
    63.57
    69.72
    72.60
    197.2
    U4.76
    193.1
    55.84
    207.2
    54.93
    200.61
    58.69
    106.7
    195.23
    210
    102.9
    186.31
    78.9
    107.88
    127.61
    204.39
    118.7
    65.38
    Valence
    3
    5
    3
    5
    3
    5
    3
    2
    6
    3
    2
    2
    1
    3
    4
    2
    3
    2
    t
    3
    4
    3
    2
    2
    2
    2
    1
    2
    4
    3
    2
    4
    2
    4
    4
    3
    2
    7
    4
    1
    4
    2
    1
    4
    2
    nig/cou-
    lomb
    0.0932
    0.2523
    0.4206.
    0.1525
    0.2587
    0.4332
    0.7219
    0.5824
    0.0898
    0.1796
    0.3054
    0.3294
    0.6588
    0.2408
    0.1881
    0.3762
    0.6812
    1.0218
    2.0435
    0.3964
    0.5003
    0.6670
    0.2893
    1.074
    0.2846
    1.0394
    2.0788
    0.3041
    0.2764
    0.3686
    0.5528
    0.5058
    1.0115
    0.5440
    0.2666
    0.3555
    0.5332
    0.2758
    0.2046
    1.1179
    0.3306
    0.6612
    2.1180
    0.3075
    0.6150
    0.3387
    g/amp hr
    0.3354
    0.9085
    1.5141
    0.5589
    0.9315
    1.5594
    2.5990
    2.097
    0.323
    0.646
    1.099
    1.186
    2.372
    0.8670
    0.6771
    1.3542
    2.4522
    3.6783
    7,3567
    1.4271
    r.sooi
    2.4012
    1.042
    3.865
    1.0746
    3.7420
    7.4839
    1.095
    0.9951
    1.3268
    1.9903
    1.8208
    3i6416
    1.958
    0.9598
    1.2797
    1.9196
    0.9929
    0.7364
    4.0245
    1.1901
    2.3803
    7.6249
    1.1070
    2.2141
    1.2195
    oz/atnp hr
    0.0118
    0.032
    0.0535
    0.0197
    0.0328
    0.055
    0.0915
    0.074
    0.0114
    0.0228
    0.0388
    0.0418
    0.0837
    0.0306
    0.02388
    0.04776
    0.0865
    0.1297
    0.2595
    0,05033
    0.06349
    O.C8469
    0.0368
    0.1362
    0.0362
    0.1320
    0.2640
    0.0386
    0.035
    0.0467
    0.0703
    0.0645
    0.1284
    0.0691
    0.0338
    0.0451
    0.0677
    0.0350
    0.0260
    0.142
    0.0420
    0.0840
    0.2583
    0.039
    0.078
    0.043
    lb/1,000
    amp hr
    0.7394
    2.0028
    3.3380
    1.2322
    2.0536
    3.4378
    5.7297
    4.6226
    0.7129
    1.4258
    2.4236
    2.6142
    5.2283
    1.9114
    1.4928
    2.9855
    5.406
    8.1094
    16.2187
    3.1461
    3.9704
    5.2938
    2.2963
    8.5210
    2.2588
    8.2496
    16.4992
    2.4135
    2.1939
    2.9252
    4.3878
    4.0142
    8.0283
    4.318
    2.1160
    2.8213
    4.2319
    2.1890
    1.6235
    8.8726
    2.6238
    5.2476
    16.8000
    2.4406
    4.8812
    2.6886
    oz/sq ft for
    sp gr 0.001 in.
    2.7
    6.68
    6.68
    5.73
    5.73
    9.8
    9.8
    8.64
    7.1
    7.1
    8.9
    8.92
    8.92
    5.9
    5.35
    5.35
    19.3
    19.3
    19.3
    7.31
    22.42
    22.42
    7.9
    11.3
    7.2
    13.55
    13.55
    8.9
    12.0
    12.0
    12.0
    21.4
    21.4
    12.5
    12.5
    12.5
    20.53
    4.81
    10.5
    6.25
    6.25
    11.85
    7.3
    7.3
    7.1
    0.225
    0.557
    0.557
    0.475
    0.475
    0.816
    0.816
    0.72
    0.591
    0.591
    0.74
    0.74
    0.74
    0.491
    0.445
    0.445
    1.61
    1.61
    1.61
    0.608
    1.869
    1.869
    0.66
    0.94
    0.598
    1.129
    1.129
    0.742
    0.998
    0.998
    0.998
    1.78
    1.78
    1.04
    1.04
    1.04
    1.710
    0.400
    0.875
    0.520
    0.520
    0.986
    0.61
    0.61
    0.59
    amp hr to
    deposit 0.001
    in./sq ft
    19.05
    17.4
    10.4
    24.1
    14.5
    14.8
    8.93
    9.73
    51.8
    25.9
    19.0
    17.7
    8.84
    16.0
    18.6
    9.31
    18.6
    12.4
    6.2
    12.1
    29.4
    22.1
    17.9
    6.91
    16.5
    8.55
    4.27
    19.0
    28.6
    21.4
    14.2
    27.6
    13.85
    30.8
    23.1
    15.37
    48.8
    15.4
    6.16
    12.4
    6.19
    3.82
    15.63
    7.82
    13.7
    amp hr to
    Symbol of aepOSlt .1 %
    element mm/sq m Eff
    Al
    Sb
    As
    Bi
    Cd 4.12 90-100
    Cr 21.9 13
    Co 8.05 100
    Cu 7.50 100
    3.74 50-100
    Ga
    Ge
    Au
    2.63 100
    In 5.13 50-80
    Ir
    Fe 7.58 100
    Pb 2.93 100
    Mn
    Hg
    Hi 8.05 100
    Pd 12.12
    9.07
    6.02
    Pt 11.69 60
    5.85 60
    Po
    Rh 13.05
    9.79 60
    6.53
    Re
    Se
    Ag 2.61 100
    Te
    Tl
    Sn 6.62 90
    3.31 100
    Zn 5.80 100 (ACID)
    60-90 (CD)
    From Electroplating  Engineering Handbook
                                                      260
    

    -------
    Average thickness can be approximated by averaging thickness
    measurements  at  several points on a single plated part, to
    establish  the  ratio  of  average  to  minimum   thickness.
    Minimum  thickness  is  customarily  monitored  to  meet the
    specifications of purchasers of electroplated  parts,  based
    on service requirements.
    
    This equation was used in this study to determine the plated
    areas  per unit time in each plating operation when the only
    available information was the current used and  the  average
    thickness  of  deposit.   This  equation  was also used as a
    check on estimates of surface area plated  provided  by  the
    plants contacted.
    
    To  calculate  the  total  plated area on which the effluent
    limitations are based for a specific plant, it was necessary
    to sum up the area  for  each  electroplating  process  line
    using  Equation  (2).   For  process lines containing two or
    more electroplating operations (such  as  in  copper-nickel-
    chromium  decorative  plating) the plated area is calculated
    by Equation (2)  for each plating operation in  the  process.
    The  results  should  be  the same, since the same parts are
    processed  through  each   operation.    However,   if   the
    calculated  plated  area differed for each plating operation
    in a single process line,  the  average  of  the  calculated
    plated  areas  for  the operations was used.  The sum of the
    plated area for each process line is the total  plated  area
    for the plant.
    
    Small discrepencies in the above calculation for two or more
    plating operations in the same process line might be related
    to  a  difference  in  the  actual current efficiencies from
    those in Table 37 which are to be used for the  calculation.
    However,  experience with data from several plants indicated
    that the  more  likely  cause  of  the  discrepancy  is  the
    accuracy of the reported values of average plate thickness.
    
    The  use  of  ampere-hour on rectifiers might have value for
    monitoring or record keeping for  some  plants  in  lieu  of
    measuring  the area of the parts plated provided the average
    thickness plated is known or determined.
    
    Records  of  plating  voltage  and  ampere-hours   on   each
    rectifier  (or watt-hours)  plus thickness deposited might be
    correlated with watt-hours of electricity consumed  per  day
    or   month   with   allowance  for  other  electricity  uses
    (lighting, pumps, etc)  to estimate total plated area per day
    or month.  The total effluent could be approximated  by  the
    plant  water  purchases if mainly for electroplating.  Thus,
    the information on  electric  power  consumption  and  water
                                  261
    

    -------
    consumption  from  monthly bills for these services might be
    used in an approximation of daily plated area  for  a  cross
    check against plated area determined by more direct means.
    
    In  practice,  it  should  be possible for electroplaters to
    readily  adapt  to  keeping  records  of  plated  area   for
    reporting  purposes.   The  fact  that  many  platers do not
    presently know their production rate  in  terms  of  surface
    area  plated  is  not  a valid consideration since there has
    been no prior requirement to keep such records.  Determining
    plated area  should  not  be  difficult  for  platers  whose
    process operation is dependent on use of the correct current
    density for optimum plating results.
        "Process";
    A process is the accumulation of steps
    required to bring about an electroplating
    result.
        "Operation";  The concept of an operation is a crucial
                     one in the formation of limitations
                     for each individual installation plant.
                     For this purpose, an operation shall
                     be defined as any step followed by
                     a rinse in the electroplating process
                     in which a metal is electrodeposited
                     on a basis material.  Electroless
                     plating on non-metallic materials
                     for the purpose of providing a
                     conductive surface on the basis
                     material and preceding the actual
                     electroplating step, and the past
                     treatment steps of chromating,
                     phosphating and coloring where an
                     integral part of the plating line
                     and stripping where conducted in
                     conjunction with electroplating for
                     the purpose of salvaging improperly
                     plated parts may be included under
                     the term operation for the purpose
                     of calculating effluent discharge.
       "Rinse";
    A rinse is a step in a process used
    to remove components of a bath from
                                    262
    

    -------
                     the work following an operation.
                     A rinse may consist of several
                     sequences such as successive
                     countercurrent rinsing or hot
                     rinsing followed by a cold
                     rinsing with deionized water.
                     Nevertheless, there is only one
                     rinse after an operation.
    
    Applying Effluent Limitation Guidelines
    
    The application of the effluent limitation guidelines
    will be illustrated by examples.  In all cases, certain
    basic information is needed from a plant:
    
          (1)   The number of operations in each process line
               including initial cleaning and pickling
               operations and all rinses
    
          (2)   The sq m/hr through each process line (average
               for 30 sequential days)
    
          (3)   The volume of effluent from the plant
               due to electroplating processes (average
               for 30 sequential days)
    
               The concentrations of waste water constituents
               in the effluent that are limited by the
               guidelines.  These are the concentrations
               in the effluent due to electroplating
               processes before dilution by effluent
               from other processes  (average for 30
               sequential days).
    
    Determination^Qf,Plated Area/Hr/Operatjon
    
    The area for each line will be determined  from  information
    on the  (1) average amperes used,  (2) the sequence of plating
    operations,  and   (3)  the  average thickness in mil of each
    type of plate.  If complete data on  thickness  is  lacking,
    the following value will be used:
    
             Copper            0.3 mil
             Nickel            0.3 mil
             Zinc              0.3 mil
             Chromium          0.015 mil
    
    Where  chromating follows plating, the area will be the same
    as that of the primary plating operation.  The equation:
                                     263
    

    -------
             S = EIT/100 kt
    
    is then used to calculate plated  area/hr/operation.   In  a
    line  with  several sequential operations, it is likely that
    the calculated plated areas for each plating operation  will
    vary  from each other although the actual area plated should
    be the same.  The difference in calculated areas may vary by
    a factor of two or three.  When applying the guidelines,.the
    figure used for area plated should be the arithmetic average
    of the calculated plated areas.
    
    Where actual amperes are not known, a value equal to 2/3  of
    the  installed  capacity for the line should be used.  Where
    information on amperes is completely lacking for a line  but
    water use is available, the sq m/hr may be determined by:
    
        Sq m/hr = 1/hr^used,on the^line
                  (200 1/sq m)(no. of operations)
    
        Sq ft/hr = gal/hr_used 011 the line
                   (5 gal/hr) (no,,  of operations)
    
    Once the plated area has been measured the guidelines can be
    used  to  determine  the  total allowable discharge of waste
    water constituents from the plant.  Every time  the  surface
    is  rinsed, following some operation in the process line, it
    is assumed that more waste water is produced, and a  greater
    quantity of waste water constituents may be discharged under
    the  guidelines.    The  cleaning  and  pickling  rinses  are
    therefore incorporated into the rinse  following  the  first
    plating  operation for purposes of calculating the allowable
    amount of waste water constituents  discharged.   The  total
    allowable discharge in g/day will be:
    
      (103) (sq m plated/hr) (effluent limitation in mg/sq m)
         (No. of oper.)(hr/day)
    
    The total allowable discharge in Ib/day is:
    
       (10«) (sq ft plated/hr) (effluent limitation
          in Ib/million sq ft (No. of oper.) (hr/day)  = Ib/day
    
    These relations hold for each effluent limitations guideline
    value  listed  in  Table  1.   The  relations  apply to each
    process line or part of a process line if the area plated/hr
    changes in the line.
    
    The actual discharge from the plant is the  product  of  the
    volume  of  effluent/hr and the concentration of waste water
    constituent in the effluent.
                                     264
    

    -------
    Thus,
    
         g/day = (liters/hr) (mg/1) (10-3) (hr/day)
        Ib/day = (8.33 x 10-*) (gal/hr) (mg/1) (hr/day)
    
    Several examples will show how the  guidelines are applied to
    specific processes.
    
    Example I.  This example  of  plating  on   steel  has  three
    operations  as  shown   in  Figure   33.   For  the purpose of
    effluent limitations the nickel strike,  nickel  plate,  and
    chromium  plate  are  the  three included operations and the
    alkaline cleaning  and   acid  pickling   operations  are  the
    excluded  operations.   The line processes an estimated 10 sq
    m/hr of work and the treatment plant discharges 3000 1/hr.
    
    Next  consideration  must  be given to what  waste  water
    constituents  can  appear  in  the water  from the line so that
    one can be  sure that the analysis  of the effluent  accounts
    for these constituents.
    
          Base  Metal Dissolution  - Iron
          Cleaning and Pickling - Phosphates, Cyanide
          Electroplating -  Nickel, Chromium (Total  and
            Hexavalent)
    
    The  concentrations  of waste water   constituents  in  the
    effluent were reported  as  follows:
    
          Phosphate                  2   mg/1
          Cyanide  (oxidizable)       0.2
          Cyanide  (total)            0.3
          Nickel                     0.6
          Chromium  (total)           O.U
          Chromium  (hexavalent)      0.03
          Total Suspended  Solids    10
          pH                         7.5
    
    The  above  data  are adequate to  determine  whether  effluent
     limitations  are   being  met.   The  actual discharge  may  be
     compared  with the allowable discharge.
    
     Actual  Discharge:
    
       (Effluent concentration, mg/1)x(Effluent discharge,  1/hr)
         (hr/day)  =  mg/day.
    
     Allowable Discharge:
    
       (Guideline,  mg/m2/operation) x  S± (m2/day) x operations!
                                    265
    

    -------
                    Electrolytic
                   Alkaline Clean
                       Ftinse
                    Acid Pickle
                       Rinse
                    Nickel Strike
                       Rinse
                    Nickel Plate
                  Chromiium Plate
    FIGURE 33  OPERATION OF A NICKEL AND
                CHROMIUM PLATING LINE
                      266
    

    -------
         = mg/day.
    
    Phosphate:
    
      Actual discharge = 2.0 x 3000 x 1/106 = 0.048 kg/day
      Allowable discharge =  (160) x 10 x 8 x 3/106 0.0384 kg/day
      Guideline not met.
    
    Cyanide (oxidizable)
    
      Actual discharge = 0.2 x 3000 x 8/106 = 4.80 x 10-* kg/day
      Allowed discharge = 8 x 10 x 8 x 3/106 = 1.92 x 10~* kg/day
      Guidelines not met.
    
    Cyanide (total)
    
      Actual discharge = 0.3 x 3000 x 8/106 = 7.20 x 10-* kg/day
      Allowed discharge = 80 x 10 x 8 x 3/106 = 1.92 x 10~3 kg/day
      Guidelines met.
    
    Nickel:
    
      Actual discharge = 0.6 x 3000 x 8/106 = 1.44 x 10~3 kg/day
      Allowed discharge = 80 x 10 x 8 x 3/106 = 1.92 x 10~3 kg/day
      Guidelines met.
    
    Chromium (total):
    
      Actual discharge = 0.4 x 3000 x 8/106 = 9.60 x 10~* kg/day
      Allowed discharge = 80 x 3000 x 8/106 = 1.92 x 10-3 kg/day
      Guidelines met.
    
    Chromium (hexavalent) :
    
      Actual discharge = 0.03 x 3000 x 8/106 = 7.20 x 10~5 kg/day
      Allowed discharge = 8 x 10 x 8 x 3/106 = 1.92 x 10~* kg/day
      Guidelines met.                      ~"
    
    Suspended Solids:
    
      Actual discharge = 10 x 3000 x 8/106 = 2.40 x 10-2 kg/day
      Allowed discharge = 3200 x 10 x 8 x~3/10~* = 7.68 x 10-2 kg/day
      Guidelines met.
    
    pH effluent limitation guidelines of 6-9 met by pH 7.5.
    
    Example	II.   Example  I  considered  one  line  to   which
    guidelines  for  one  subcategory  applied.   Plants  almost
    invariably involve more than one line  and  process.   Where
    one  subcategory is involved for several lines and processes
                                    267
    

    -------
    for calculation to determine effluent limitations guidelines
    is essentially identical to that of Example I.  A flow sheet
    for two electroplating lines (and  processes)   is  shown  in
    Figure 34.  The base metal is steel.
    
    Zinc  plating is the included operation in Line 1 and copper
    plating is the included operation in Line 2 for the  purpose
    of  establishing  effluent  limitations  guidelines.  Line 1
    processes 10 sq m/hr of work and Line 2 processes 5 sq  m/hr
    of  work.   Effluent  volume due to both lines is 1000 1/hr.
    The plant operates 16 hr/day.
    
    Constituents  subject  to  effluent  limitations  guidelines
    expected in waste water are
    
          Base Metal Dissolution - Iron
          Cleaning and Pickling - Phosphate, Cyanide
          Electroplating - Zinc, Copper, Cyanide
    
    The  concentrations  of  waste  water  constituents  in  the
    effluent were reported as follows:
    
        Phosphate               1    mg/1
        Cyanide (total)          0.1  mg/1
        Cyanide (oxidizable)    0.02 mg/1
        Chromium (total)        0.1  mg/1
        Chromium (hexavalent)   0.06 mg/1
        Total Suspended Solids 15    mg/1
        pH                      6,5  mg/1
    
    Calculations are similar to those for Example I.
    
    Phosphate:
    
      Actual Discharge = 1.0 x 1000 x 16/106 = 1.60 x 10-3 kg/day
      Allowed Discharge = 160 x  (10 x 1 + 5 x 1)  x 16/106 =
                          3.84 x 10-3 kg/day
      Guidelines met.
    
    Calculations for other constituents  are  identical,  except
    for   changes   in  concentrations  for  determining  actual
    discharge and changes in effluent limitation guidelines  for
    determining allowed discharge.
    
                          Actual Discharge,   Allowed Discharge,
    Constituent                  Ka^lY.              kg /day
    Phosphate                1.60 x 10-3         3.84 x 10-3
    Cyanide  (total)          1.60 x 10~*         1.92 x 10- 3
    Cyanide  (oxidizable)     3.20 x 10-s         1.92 x 10-*
                                   268
    

    -------
    Line 1
    Line 2
                                            Electrolytic Clean
                                                 Rinse
                                              Acid Pickle
                                                 Rinse
                                              Copper Plate
    
                                             (cyanide bath)
                                                   I
                                                 Rinse
      FIGURE 34  SIMULTANEOUS OPERATION OF ZINC
                  AND COPPER PLATING LINES
                          269
    

    -------
    Chromium (total)          1.60 x 10-*         1.92 x 10-3
    Chromium (hexavalent)    9.60xlO~5         1.92x 10-*
    Total Suspended Solids   2.40 x 10~2         7.68 x 10~«
    pH                            6.5                6-9
    
    Actual discharge amounts meet guidelines in all cases.
    
    Example	III.   A more complex situation is encountered when
    more than one process is operating simultaneously in a plant
    but processes may be found in more than one subcategory.  In
    such a case, the effluent limitation guideline for more than
    one subcategory must be considered.  Figure 35 shows a  line
    for electroless plating on plastics (Subcategory (2)) and an
    electroplating   nickelchromium   line   (Subcategory   (1))
    operating  in  sequence.   The  plant  may   consider   both
    processes  as  one  line,  but  for  purposes of considering
    whether effluent limitations guidelines are being  met,  the
    sequence  must  be  considered  as  made  up of two separate
    processes.
    
    The electroless process plates 10 sq m/hr of work.   Of this,
    9 sq m/hr continue through the electroplating process  while
    1  sq  m/hr  is finished after the electroless process or is
    rejected.  The volume of effluent from the two processes  is
    5000  1/hr.   The  plant  operates  10  hours  per day.  The
    included  operations  for   determining   whether   effluent
    limitations  guidelines  are  met  are,  for the electroless
    process
    
        Sensitize
        Activate
        Electroless Nickel
    
    and for the electroplating process
    
        Acid copper Strike
        Nickel Electroplate
        Chromium Electroplate.
    
    Constituents  subject  to  effluent  limitations  guidelines
    expected in waste waters are
    
        Cleaning and Pickling - Phosphate, Chromate
        Electroless Plating - Nickel
        Electroplating - Copper, Nickel, Chromium.
    
    The  concentrations  of  waste  water  constituents  in  the
    effluent were reported as follows
    
        Phosphate                        2    mg/1
                                    270
    

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      Soak Clean
         Rinse
       Acid Dip
         Rinse
        Sensitize
         Rinse
          Rinse
     Electroless Nickel
          Rinse
    Acid Copper Strike
                                                      Rinse
                                                Nickel Electroplate
                                                      Rinse
                                              Chromium Electroplate
                                                      Rinse
     FIGURE 35  ELECTROLESS NICKEL PLATING OF PLASTIC PLUS
                 NICKEL-CHROMIUM ELECTROPLATING
                                 271
    

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        Chromium (total)
        Chromium (hexavalent)
        Copper
        Nickel
        Total Suspended Solids
        pH
     0.3
     0.03
     0.
     0
    25
     8.0
                     5
                     7
    The actual amount of  discharge  is  calculated  as  in  the
    previous examples.  The allowable discharge is calculated by
    determining  the  mg/day for the elctroless plating process,
    which is in Subcategory (2) and adding to the mg/day for the
    nickel and chromium processes, which are in Subcategory  (1).
    ±(320) (10) (10) (3)
    kg/day.
    (160) (9) (10) (3) 1/10*   =  1.39  x
    Allowable  discharges for other constituents are made in the
    same manner,  using  appropriate  values  for  the  effluent
    limitations.
    Phosphate
    Chromium  (total)
    Chromium  (hexavalent)
    Copper
    Nickel
    Total suspended Solids
    pH
        Actual Discharge
            kg/day.
    
         1.00 x 10-2
         1.50 x 10-3
         1.50 x 10-*
         2.50 x 10-3
         3.50 x 10-3
         1.25 x 10-»
             8.0
            Allowed Discharge
                _kg/day
    
            1.39 x 10-2
            6.96 x 10-3
            6.96 x 10-*
            6.96 x 10-3
            6.96 x 10-3
            2.78 x 10-»
                6-9
    It  is  apparent  from  Example III how a plant with diverse
    processes can be analyzed.  All  of  the  electroplating   is
    divided  into individual processes; each process is assigned
    to the appropriate  Subcategory;  the  square  meters   going
    through  each  process  is  estimated;  the  total volume  of
    effluent  due  to  the  electroplating  processes  and  the
    concentration  of  waste  water  constituents in the treated
    effluent are determined. The calculations are than  made   as
    shown in Example III.
                                       272
    

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                             SECTION X
    
              BEST AVAILABLE TECHNOLOGY ECONOMICALLY
    Introduction
    
    The  effluent  limitations  which  must  be achieved July 1,
    1983, are  to  specify  the  degree  of  effluent  reduction
    attainable  through  the  application  of the Best Available
    Technology Economically Achievable.  This technology can  be
    based  on  the  very  best  control and treatment technology
    employed by a specific  point  source  within  the  industry
    category  and/or  subcategory  or technology that is readily
    transferable  fron  one  industry  process  to  another.   A
    specific  finding  must  be  made  as to the availability of
    control measures and practices to eliminate the discharge of
    pollutants, taking into account the cost  of  such  elimina-
    tion.
    
    Consideration must also be given to
    
          (a)  the age of the equipment and facilities
              involved
    
          (b)  the process employed
    
          (c)  the engineering aspects of the application
              of various types of control technologies
    
          (d)  process changes
    
          (e)  cost of achieving the effluent reduction
              resulting from the technology
    
          (f)  nonwater quality environmental impact
               (including energy requirements).
    
    The   Best   Available Technology Economically Achievable also
    assesses  the  availability  in  all  cases  of   in-process
    controls  as  well  as  the  control or additional  treatment
    techniques  employed at the end of  a production process.
    
    A further consideration is the availability of processes and
    control technology at the pilot plant,  semiworks,   or   other
    levels,   which   have   demonstrated   both   technological
    performances  and economic viability at  a level sufficient to
    reasonably   justify  investing  in such   facilities.    Best
    Available   Technology Economically Achievable is the highest
                                   273
    

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    degree of control technology that has been achieved  or  has
    been  demonstrated to be capable of being designed for plant
    scale  operation  up  to  and  including  no  discharge   of
    pollutants.   Although  economic factors are considered, the
    costs for this level of control are intended to  be  top-of-
    the-line   of  current  technology  subject  to  limitations
    imposed by economic and engineering  feasibility.   However,
    Best  Available  Technology  Economically  Achievable may be
    characterized  by  some  technical  risk  with  respect   to
    performance  and with respect to certainty of costs and thus
    may necessitate some industrially sponsored  work  prior  to
    its application.
    
    Industry Category and Subcateorory Covered
    
    The   pertinent  industry  category  is  the  electroplating
    industry as previously discussed in Section IV.
    
                   Qf Best Available Economically Achievable
    No discharge of metals in effluent may be achieved  only  by
    eliminating  the  effluent  itself  by  such  techniques  as
    reverse osmosis and evaporation, which offer the possibility
    of purifying all waste water to a sufficient  degree  to  be
    recycled  to  process  or  by evaporating to dryness so that
    waste water constituents are disposed of as solid waste.
    
    No  generalization  regarding  degree  of  metal   pollution
    reduction  is  possible  because  of  the  mix  of finishing
    processes possible in a single plant and variety  of  metals
    in  the  raw waste of most plants.  Because of this fact and
    the high cost of inplant segregation of  all  waste  streams
    according to metal, coprecipitation of metals is the general
    practice.   There  is  an  optimum pH for precipitating each
    metal that results in the greatest removal by clarification.
    
    There are several advanced recovery  methods  available  for
    closing   up   the   rinse   water   cycle   on   individual
    electroplating operations.  These methods (evaporation,  ion
    exchange,  reverse osmosis, counter current rinsing) have not
    yet been applied  to  rinse  waters  from  pretreatment  and
    posttreatment  operations.   The  corresponding rinse waters
    plus  concentrated  solution  dumps  and  floor  spills  may
    contain  one or all of the pertinent metals (copper, nickel,
    chromium,  and  zinc)   in  significant   amounts   requiring
    chemical  treatment.   Thus,  chemical treatment of at least
    the  typical  acid/  alkali  stream  from  pretreatment  and
    posttreatment  operations  represents  the  best practicable
    control  technology  currently  available  to  achieve   the
    effluent limitations recommended.
                                   274
    

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    The Best Available Technology Economically Achievable is the
    use  of  in-process and end-of-process control and treatment
    to achieve no discharge of pollutants.  By the  use  of  in-
    process  controls  to  reduce  the volume of waste water, it
    becomes economical to use end-of-process treatment  designed
    to  recover  water and reuse the water within the plant thus
    avoiding any discharge  of  effluent  to  navigable  waters.
    Solid  constituents  in  the  wastewater  are disposed of to
    landfill or otherwise.  A line in Plant 30-21 plating silver
    has eliminated liquid effluent discharge for several months,
    and continued demonstration of this operation  will  support
    the  fact  that  technology  is  available  to achieve this.
    Plant 11-22, which does mostly chromium plating, studied  in
    Phase  I,  is  using  a  system designed to eliminate liquid
    effluent by subjecting effluent from the  clarifier  of  the
    chemical  treatment  plant  to reverse osmosis and recycling
    water to process.  The concentrate from the reverse  osmosis
    unit  is  evaporated  to dryness.  It is expected that other
    methods will be developed during  the  next  five  years  to
    avoid  discharge  of  effluent  to navigable waters and thus
    achieve no discharge of pollutants in an economical manner.
    
    Batignale_for selection^of Best Available
    TechnologY_EconomicallY_Achievable  ~"  ~~
    
    Age of Equipment and Facilities
    
    Replacement of older equipment and  facilities  will  permit
    the  installation of modern multitank countercurrent rinsing
    systems after each  operation  in  each  process  line  with
    conservation  of  water use for rinsing.  The use of reclaim
    and recovery systems after each finishing  operation  should
    be  possible.   Use  of  inprocess  controls  to the maximum
    extent will reduce the volume of effluent to the point  that
    recovery and reuse of water is economically feasible.
    
    Process Employed
    
    The   application   of  the  technology  for  end-of-process
    recovery and reuse of water to the maximum  extent  possible
    is  not dependent on any significant change in the processes
    now used.  Most water  recovery  technology  can  produce  a
    higher  quality of water than normally available from public
    or private water supplies.  High purity water for the  final
    rinse   after  electroplating  operations  is  desirable  to
    improve the quality of the product.
    
    Engineering Aspects of the Application of Various  Types  of
    Control Techniques
                                   275
    

    -------
    Many  plants  are  successfully  using  evaporative recovery
    systems after one or more  plating  operations  with  a  net
    savings compared to chemical treatment.   Evaporative systems
    are  in  current  use  after copper, nickel, chromium, zinc,
    brass, tin, lead, and gold plating operations.  Some  plants
    have  succeeded  in using recovery systems after all plating
    operations in their facility,,  The  engineering  feasibility
    of  in-process  controls for recovery of chemicals and reuse
    of water  are  sufficiently  well  established.   Sufficient
    operational use has been accumulated to reduce the technical
    risk  with  regard  to  performance and any uncertainty with
    respect to costs.
    
    The technical feasibility of end-of -pro cess  water  recovery
    systems has been established by extensive development of the
    recovery of pure water in many related industrial processes.
    Although  some uncertainty may remain concerning the overall
    costs  when  applied  to  electroplating  wastewaters,  such
    uncertainty  primarily  relates  to the volume of water that
    must be processed for recycling and reuse.   The  fact  that
    the technology as applied to the electroplating industry has
    progressed  beyond  the  pilot  plant  stage  and  has  been
    designed and is being built for  fullscale  operational  use
    indicates  that  the  technology  is  available and probably
    economical.   These  systems  are  equally   applicable   to
    processes other than electroplating due to the similarity in
    the waste water produced.
    Application  of  the  technology  is  not  dependent  on any
    process changes.  However, process changes and  improvements
    are  anticipate  to  be a natural consequence of meeting the
    effluent limitations in the most economic manner.
    
    Nonwater^ Quality Environmental Impact
    
    Application  of  technology  to  achieve  no  discharge   of
    pollutants  to  navigable  waters by July 1, 1983, will have
    little impact on  the  solid  waste  disposal  problem  with
    regard  to metal removal as sludge beyond that envisioned to
    meet effluent limitations recommended for July 1, 1977.  The
    volume of soluble salts will be substantially increased.
    
    In general, it is anticipated that the  technology  will  be
    applied  in  a  manner such that no discharge of effluent to
    surface waters occurs.  Thus,, metal oxide sludges  would  be
    disposed  of  either on land with suitable precautions.  The
    soluble salts, largely  innocuous  should  be  suitable  for
    disposal  in  the  salt  water.  Because these salts are not
                                  276
    

    -------
    large in amount and can  be  dewatered  to  dry  solids  (by
    incineration  if necessary) very little additional impact on
    the solid waste disposal problem is anticipated.
    
    No impact of air pollution is  expected  as  the  result  of
    achieving  no discharge of pollutants to surface water.  The
    available technology creates no air pollutants.
    
    Ef^uenj^Ljjnita^j^ns_Ba^eJ^n_^e_Aj3Bcjtion of gest
    Available_Technoloiy._iS2U2nii£lily
    The recommended effluent limitations to be achieved by  July
    1,  1983,  for  existing sources based on the application of
    Best Available  Technology  Economically  Achievable  is  no
    discharge  of pollutants to navigable waters for Subcategory
    1.
    
    guidelines for the Application of Effluent Limitations
    
    Achieving  the  effluent  limitations  of  no  discharge  of
    pollutants  by achieving no discharge of effluent to surface
    waters is the most direct methods that eliminates  the  need
    for  sampling  and  analysis.   If  there  is other effluent
    discharge to surface waters from the  plant  not  associated
    with  electroplating,   a  determination  is required that no
    waste waters originating from metal finishing processes  are
    admixed with this other plant effluent.
                                     211
    

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                             SECTION XI
    
                  NEW SOURCE PERFORMANCE STANDARDS
    
    Introduction
    
    The  standards  of performance which must be achieved by new
    sources  are  to  correspond  to  the  degree  of   effluent
    reduction  attainable  through  the  application  of  higher
    levels of pollution control than those  identified  as  Best
    Available  Technology  Economically  Achievable for existing
    sources.  The added consideration for  new  sources  is  the
    degree  of  effluent reduction attainable through the use of
    improved production processes and/or  treatment  techniques.
    The  term  "new  sources" is defined by the Act to mean "any
    source,  the  construction  of  which  is  commenced   after
    publication  of  proposed regulations prescribing a standard
    of performance".
    
    New Source Performance Standards are based on the  best  in-
    plant  and  end-of-process  technology  identified  as  Best
    Available Technology Economically  Achievable  for  existing
    sources.  Additional considerations applicable to new source
    performance  standards  take  into  account  techniques  for
    reducing the level of effluent by  changing  the  production
    process  itself or adopting alternative processes, operating
    methods, or other alternatives.  The end result will be  the
    identification of effluent standards which reflect levels of
    control  achievable  through  the use of improved production
    processes (as  well  as  control  technology) ,  rather  than
    prescribing a particular type of process or technology which
    must  be  employed.  A further determination must be made as
    to whether a standard permitting no discharge of  pollutants
    is practicable.
    
    Consideration must also be given to:
    
         (a)  The type of process employed and process
              changes
    
         (b)  operating methods
    
         (c)  batch as opposed to continuous operations
    
         (d)  use of alternative raw materials and mixes
              of raw materials
    
         (e)  use of dry rather than wet processes
              (including substitution of recoverable
              solvents for water)
                                   279
    

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         (f)   recovery of pollutants as by-products.
    
    Standards  of  Performance  for  New  Sources  are  based on
    applicable  technology  and  related  effluent   limitations
    covering discharges directly into waterways.
    
    Consideration  must also be given to the fact that Standards
    of Performance for  New  Sources  could  require  compliance
    about three years sooner than the effluent limitations to be
    achieved  by existing sources by July 1, 1977.  However, new
    sources should achieve  the  same  effluent  limitations  as
    existing sources by July 1, 1983.
    
    Industry Cateqory^and^SubcategorY,Covered
    
    The   pertinent  industry  category  is  the  electroplating
    industry as previously discussed in Section IV.
    
    Identif3,cation_Qf Control and^Treatment
    Technology Applicable to Performance
    Standards and Pretreatment Standards of
    New Sources
    
    The technology previously identified in Section IX  as  Best
    Practicable  Control  Technology Currently Available is also
    applicable to New Source Performance Standards.  In addition
    a New Source can utilize  the  best  practice  in  multitank
    rinsing  after  each operation in the process as required to
    meet the effluent limitations at the time  of  construction.
    Thus,   with   no  practical  restrictions  on  rinse  water
    conservation after  each  operation  by  multitank  rinsing,
    there   are  fewer  restrictions  on  the  use  of  advanced
    techniques for recovery of bath chemicals and  reduction  of
    wastewater    from    rinsing    after    pretreatment   and
    posttreatment.  Maximum use of combinations of  evaporative,
    reverse  osmosis,  and  ion  exchange systems for in-process
    control currently available should be investigated.  A small
    end-of-pipe chemical treatment system can be used  to  treat
    spills,  concentrated  solution  dumps,  and any other water
    flows not economically  amenable  to  in-process  water  and
    chemical recovery.
    
    The  net  result  of  the  improvements  cited  should  be a
    reduction in  water  use  as  compared  to  that  considered
    achievable for Best Practicable Control Technology Currently
    Available.    This   reduction  should  result  in  a  lower
    discharge of waste water constituents.  Although methods are
    being developed that may make possible a  further  reduction
    in  the concentration of constituents and a reduction in the
                                 280
    

    -------
    discharge  of waste water constituents in chemically treated
    effluents, present technology is capable only  of  achieving
    the  concentrations listed in Table 66 by exemplary chemical
    treatment.  It would be anticipated  that  some  plants  now
    operating,  due to having been designed recently to minimize
    water use or because of other favorable  circumstances  such
    as  adequate  space  to  make modifications, are attaining a
    water use well below 160 1/sq m/operation.  Table  64  shows
    16  lines  involving  processes  that achieve a water use of
    less than 80 1/sq m/operation.  These are  found  in  Plants
    36-12,  30-2,  33-24, 15-3, 6-36, 33-23, 33-35, 20-22, 30-9,
    9-2, 6-37, 20-25, and 23-8.  The processes involved are rack
    and barrel plating of common metals, rack and strip  plating
    of   precious   metals,  anodizing,  chemical  milling,  and
    phosphating.  It is estimated that a new source  can  easily
    achieve  a  water  use  of 80 1/sq m/operation by use of the
    technology described above for reducing water use.
    
    Rationale for Selection of Control and
    Treatment Technology Applicable to New
    Source Performance Standards
    
    The rationale for the selection of the above  technology  is
    applicable to new sources discharging to navigable waters is
    as follows:
    
          (1)  In contrast to an existing source, a new
              source has complete freedom to choose the
              most advantageous equipment and facility
              design to maximize water conservation by
              use of as many multitank rinsing operations
              as necessary.  This, in turn, allows for
              economic use of in-process controls for
              chemical and water recovery and reuse.
    
          (2)  In contrast to an existing source which may
              have at present a large capital investment
              in waste treatment facilities to meet
              effluent limitations by July 1, 1977, a new
              source has complete freedom in the selection
              the design of new waste treatment facilities.
    
          (3)  In contrast to an existing source, a new
              source has freedom of choice with regard to
              geographic location.
                                281
    

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    Standards of Performance Applicable to New Sources
    
    The recommended Standards of Performance to be  achieved  by
    new  sources  discharging  to  navigable  waters  was  shown
    previously in Table 2 of Section II.
    
    The quantitative values for the 30-day average standard  for
    each  parameter  in  mg/sq  m  (lb/10°  sq ft) is based on a
    nominal water use one-half as large as those used to develop
    BPCTC guidelines combined with the concentrations achievable
    by chemical treatment as previously shown  in  Table  66  of
    Section IX.  For example, 0.5 mg/1 for copper, nickel, total
    chromium,  zinc, and total cyanide, 0.05 mg/1 for hexavalent
    chromium and  oxidizable  cyanide,  15  mg/1  for  suspended
    solids,  when  combined with an effluent factor of 40 1/sq m
    are  the  basis  for  the  30-day   average   standards   of
    performance found in Table 2.
    
    In effect, Standards of Performance for New Sources as shown
    in   Table  2,  are  1/2  of  the  values  of  the  Effluent
    Limitations for existing sources to be achieved by  July  1,
    1977,  as  shown in Table 1.  The rationale for selection of
    Standards  of  Performance  is  based   on   the   technical
    feasibility  of  achieving greater reduction in water use by
    multitank  rinsing  at  the  time  of  construction  of  new
    facilities  in  contrast to the present limitations for some
    existing sources.  For example, if an  existing  source  can
    achieve  water use of 80 1/sq m, a new source should be able
    to design a new facility to achieve a water use of  40  1/sq
    m.   As  discussed previously in Section IX, the Standard of
    Performance in mg/sq m is the product of the  water  use  in
    1/sq m and the concentration of the parameter in the treated
    effluent   in   mg/1.   The  choice  of  whether  to  reduce
    concentration by emphasis on optimum chemical treatment  and
    clarification  or whether to reduce effluent volume by water
    conservation or a combination of both approaches is left  to
    the discretion of the new source.
    
    The  rationale  for  establishing the daily maximum value of
    Standards of Performance at 2.0 times the 30-day average  is
    based on the arguments given in Section IX.
    
    It  is  recommended  that new sources meet the same effluent
    limitations as required for  existing  sources  by  July  1,
    1983,  based  on  the  effluent  reduction  believed  to  be
    attainable  by  the  application  of  the   Best   Available
    Technology Economically Achievable.
                             282
    

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    Guidelines for the Application of
    New Source Performance Standards
    
    The  recommended guidelines for the application of Standards
    of Performance for  New  Sources  discharging  to  navigable
    waters  are  the  same  as  those  in Section IX relating to
    existing sources  based  on  use  of  the  Best  Practicable
    Control  Technology Currently Available and those in Section
    X based on use of  Best  Available  Technology  Economically
    Achievable.
                                   283
    

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                            SECTION XII
    
    
                          ACKNOWLEDGEMENTS
    
    
    The   Environmental  Protection  Agency  was  aided  in  the
    preparation  of  this  Development  Document   by   Battelle
    Columbus  Laboratories  under  the  direction  of William H.
    Safranek, Luther Vaaler, John  Gurklis  and  Carl  Layer  on
    Battelle1s staff made significant contributions.
    
    Kit  R.  Krickenberger  served  as  project  officer on this
    study.  Allen Cywin, Director, Effluent Guidelines Division,
    Ernst P. Hall, Deputy Director, Effluent Guidelines Division
    and Walter J. Hunt, Chief, Effluent  Guidelines  Development
    Branch,   offered   guidance  and  suggestions  during  this
    program.
    
    The members of  the  working  group/steering  committee  who
    coordinated the internal EPA review are:
    
        Walter J. Hunt, Effluent Guidelines Division
        Kit R. Krickenberger, Effluent Guidelines Division
        Devereaux Barnes, Effluent Guidelines Division
        Murray Strier, Office of Permit Programs
        John Ciancia, NERC, Cincinnati,  (Edison)
        Alan Eckert, Office of General Counsel
        James Kamihachi, Office of Planning and Evaluation
    
    Acknowledgement  and  appreciation  is  also  given to Nancy
    Zrubek, Kaye Starr,  and  Alice  Thompson  of   the  Effluent
    Guidelines Division for their effort  in the typing of drafts
    and   necessary  revisions, and the final preparation of this
    document.
    
    Appreciation is  extended  to  the   following   organizations
    associated with the electroplating industry:
    
           American Electroplaters1 Society, East Orange,
             New Jersey
           Aqua-Chem, Milwaukee,  Wisconsin
           Artisan Industries, Inc., Waltham, Massachusetts
           E.I. duPont  de Nemours  and Co.,  Wilmington,
             Delaware
           Heil Process  Equipment corporation, Cleveland,
             Ohio
           Haviland Products Company, Grand Rapids,  Michigan
           Industrial Filter and  Pump Manufacturing  Co.,
             Cicero, Illinois
                                     285
    

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    Institute of Printed Circuits, Chicago, Illinois
    Ionic International, Incorporated, Detroit,
      Michigan
    Lancy Laboratories, Zelienople, Pennsylvania
    MOT Chemicals, Incorporated, Matawan, New Jersey
    Electroplating Suppliers" Association, Incorporated,
      Birmingham, Michigan
    National Association of Metal Finishers, Upper
      Montclair, New Jersey
    Osmonics, Incorporated, Minneapolis, Minnesota
    Oxy Electroplating Corporation, Warren, Michigan
    The Permutit Company, Paramus, New Jersey
    Pfaudler Sybron Corporation, Rochester, New York
                             286
    

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                            SECTION XIII
    
    
                             References
    
    (1)   Table 3,  pg 36,  "1967 Census of Manufacturers",
         U.S.  Bureau of Commerce.
    
    (2)   "Where to Buy Electroplating Services", Modern
         Metals,  28 (6),  p. 71 (July, 1972).
    
    (3)   Institute of Printed Circuits, Chicago, Illinois.
    
    CO   Electroplating,  p. 42, March 1972.
    
    (5)   Sidney B. Levinson, J. Paint Technology, 44 (569) 49.
    
    (6)   J.  Schrantz, Industrial Finishing, 20-29, October, 1972.
    
    (7)   Table 3,  p. 7-45, "1967 Census of Manufacturers",
         U.S.  Bureau of Commerce.
    
    (8)   Modern_Electroplating, Edited by F.A. Lowenheim,
         2nd Ed.,  John Wiley~and Sons  (1963), Chap. 7,
         pp 154-205.
    
    (9)  ^Electroplating^Guidebook and Directory, Metals
         and Plastics Publications, Inc., 1973.
    
    (10)^Electroplating .Guidebook and Directory, Metals
         and Plastics Publications, Inc. 1972.
    
    (11)  Modern Electroplating, p 698.
    
    (12)  Modern Electroplating, p 708.
    
    (13)  Electroplating^Engineerinq Handbook,  A Kenneth  Graham,
         Ed.,""van Nostrand RhelnholdT  3rd Ed., 1971, p  486.
    
    (14)  Schrantz, J. Industrial Finishing, April, 1973,
         pp 37-40.
    
    (15)  Stiller,  Frank P..r Metals Finishing Guidebook and
         Directory, Metals and Plastics Publications, Inc. ,
         pp 548-553, 1972.
    
    (16)  George, D.J., Walton, C.J., and Zelly, W.G., Aluminum
         Fabrication_and_Finishinc[, Vol 3, Am Soc for Metals,
         19677 pp~387-622.
                                   287
    

    -------
    (17)  Innes,  W.P.r  Electroplating Guidebook. and Directory,
         1972,  p 554."
    
    (18)  Pocock, Walter,  E.  Electroplating Guidebook and
         and Directory,  1972,  pp 568-575.              ~
    
    (19)  Ostrander,  C.W. ,  Electroplating Engineering Handbook,
         pp 437-447.
    
    (20)  Maher,  M.F. ,  and Prodel, A.M. , Electroplating_6uidebook
         and Directory.  1972,  pp 590-603.
    
    (21)  ASM Handbook. Vol 2,  8th Ed.,  1964, pp 531-547.
    
    (22)  Olsen,  Alan E.,  Upgrading Electroplating Facilities
         to Reduce Pollution,  EPA Technology Transfer Seminar,
         New York, New York, December,  1972.
    
    (23)  George, D.J. , Walton, c. J. , Zelley, W.G., Aluminum
         Fabrication and Finishing. Vol 3, pp 587-622.
    
    (24)  Fishlock, D., Metal Coloring,  Robert Draper, Ltd.,
         Teddington, Great Britain, 1962, pp 300-353.
    
    (25)  Safranek, W.H.,  Colored .Finishes for Copger ..and
         Copper All oys ,  Copper Division Association, New
         York,  New York,  1968.
    
    (26)  Metals Handbook,  American Society for Metals, 8th Ed.,
         1964,  Vol 2,  pp 611-660.
    
    (27)  Faust,  C.L. ,  Metals Handbook,  1964, pp 484-488.
    
    (28)  Pourbaix, Marcel, Atlas of Electrochemical Equilibria
                            s, Pergamon Press, New York (1966).
    (29)  H.  Schlegel,  Metallqher f lache , 17, 129 (1963).
    
    (30)  Hartinger, Ludwig, Baender, Bleche, Rohre, 1963,
         pp 535-540;  1963, pp 638-647; 1964, pp 14-21;
         1965,  pp 524-533.
    
    (31)  Personal communication from Dr. Coleman, Western
         Electric Company, Indianapolis, Indiana.
    
    (32)  Tripler, A. B. , Cherry, R.H., Smithson, G. Ray,
         "Summary Report on the Reclamation of Metal Values
         from Electroplating Waste Treatment Sludges",
         Battelle Columbus Laboratories report to Metal
         Finisher's Foundation, July 6> 1973.
                                  288
    

    -------
    (33)  Environmental Sciences,  Inc.,  "Ultimate Disposal
         of  Liquid Wastes by Chemical Fixation".
    
    (34)  Dodge,  B.F.,  and Zabban. W., "Disposal of Plating
         Room wastes.  III.  Cyanide Wastes"  Treatment with
         Hypochlorites and Removal of Cyanates", Plating
         38  (6), 561-586  (June, 1951).
    
    (35)  Dodge,  B.F.,  and Zabban, W., "Disposal of Plating
         Room Wastes.  III.  Cyanide Wastes: Treatment with
         Hypochlorites and Removal of Cyanates.  Addendum",
         Plating, 39 (4) , 385  (April, 1952) .
    
    (36)  Dodge,  B.F.,  and Zabban, W., "Disposal of Plating
         Room Wastes.  IV.  Batch Volatilization of Hydrogen
         Cyanide From Aqueous Solutions of Cyanides",
         Plating, 39 (10), 1133-1139 (October, 1952).
    
    (37)  Dodge,  B.F.,  and Zabban, W., "Disposal of Plating
         Room Wastes.  IV.  Batch Volatilization of Hydrogen
         Cyanide From Aqueous  Solutions of Cyanides.
         Continuation", Plating, 39  (11), 1235-1244  (November,
         1952).
    
    (38)  "Overflow", Chemical Week, 111  (24),  47  (December,
         1972) .
    
    (39)  Oyler,  R.W., Disposal of Waste Cyanides  by Electro-
         lytic Oxidation", Plating, 36  (4), 341-342  (April,
         1949) .
    
    (40)  Kurz, H., and Weber,  W., "Electrolytic Cyanide
         Detoxication by  the CYNOX  Process", Galvanotechnik
         and oberflaechenschutz, 3, 92-97  (1962).
    
    (41)  "Electrolysis  Speeds  Up Waste  Treatment",  Environmental
         Science  and Technology", 4 (3), 201  (March,  1970).
    
    (42)  Thiele,  H., "Detoxification of Cyanide-Containing
         Waste Water by Catalytic Oxidation and Adsorption
         Process", Fortschritte  Wasserchemie Ihrer
         Grenzgebiete,  9, 109-120  (1968):  CA,  70, 4054
          (1969)  .
    
    (43)  Bucksteeg, W.,  "Decomposition  of  Cyanide Wastes by
         Methods  of Catalytic  Oxidation Absorption",  Proceedings
         of the  21st Industrial  Waste conference, Purdue
         University Engineering  Extension  Series, 688-695
          (1966)  .
                                 289
    

    -------
     (44) "Destroy Free Cyanide In Compact, Continuous  Unit",
         Calgon Corporation Advertisement, Finisher*s
         Management, 19  (2) , 14  (February, 1973) ,.
    
     (45) Sondak, N.E., and Dodge, B.F., "The Oxidation
         of Cyanide Bearing Plating Wastes by Ozone.
         Part I", Plating, 48  (2) 173-180  (February,
         1961).
    
     (46) Sondak, N.E., and Dodge, B.F., "The Oxidation
         of Cyanide Bearing Plating Wastes by Ozone.
         Part II", Plating, 48 (3), 280-284  (March,
         1961).
    
     (47) Rice, Rip G., letter from Effluent Discharge
         Effects Committee to Mr. All-en Cywin, Effluent
         Guidelines Division, July 9, 1973.
    
     (48) "Cyanide Wastes Might Be Destroyed at One-Tenth
         the Conventional Cost",  Chemical Engineering,
         79 (29), 20 (December 25, 1972).
    
     (49) Manufacturers1 Literature, DMP Corporation,
         Charlotte,  North Carolina (1973).
    
     (50) Ible, N., and Frei,  A.M., "Electrolytic Reduction
         of chrome in Waste Water", Galvanotechnik and
         Oberflaechenschutz,  5 (6), 117-122 (1964).
    
     (51) Schulze, G., "Electrochemical Reduction of
         Chromic Acid-Containing Waste water", Galvanotechnik,
         58 (7), 475-480 (1967):  CA,  68, 15876t  (1968).
    
     (52) Anderson, J.R., and Weiss, Charles 0., "Methods
         for Precipitation of Heavy Metal Sulfides",
         U.S.  Patent No. 3,740,331, June 19,  1973.
    
    (53) Lancy,  L.E., and Rice, R.L.,  "Upgrading Metal
         Finishing Facilities to Reduce Pollution",
         Paper presented at the EPA Technology Transfer
         Seminar,  New York, New York (December, 1972).
    
    (54) Ele£tro2la^ijiGLEjigineer;inc[_Handbook,  Edited by
         A.K.  Graham, 3rd Edition, Van~Nostrand Reinhold
         Company,  New York (1971).
    
    (55)  Olsen,  A.E., "Upgrading  Electroplating Facilities
         to Reduce Pollution;  In-Process Pollution Abatement
         Practices",  paper presented at the EPA Technology
                                  290
    

    -------
         Transfer  Seminar,  New York,  New York (December, 1972).
    
    (56)  Novotny,  C.J.,  "Water Use and Recovery", Finishers'
         Management,  18  (2),  H3-H6 +  50 (February, 1973).
    
    (57)  Rushmere, J.D.,  "Process for Brightening Zinc
         and Cadmium  Electroplates Using an Inner Salt
         of  a Quaternary Pyridine Carboxylic Acid and
         Composition  Containing the Same", U.S.  Patent
         3,411,996, November, 1968.
    
    (58)  Ceresa, M.,  and Lancy, L.E., "Electroplating
         Waste Disposal.  Part II", Electroplating,
         66  (5) ,  60-65  (May,  1968) .
    
    (59)  Ceresa, M.,  and Lancy, L.E., "Electroplating
         Waste Disposal.  Part III", Electroplating,
         66  (6) ,  112-118 (June, 1968) .
    
    (60)  Brown, C.J., et al., "Plating Waste Recovery by
         Reciprocating-Flow Ion Exchange", Technical
         Conference of  the  American Electroplaters1
         Society,  Minneapolis, Minnesota, June 18, 1973.
    
    (61)  Metal Market,  April  17, 1972, p 21.
    
    (62)  Oh, C.B., and  Hartley, H.S., "Recycling Plating
         Wastes by Vapor Recompression", Products
         Finishing, 36  (8), 90-96  (May, 1972).
    
    (63)  Kolesat,  T.J.,  "Employment of Atmospheric Evaporative
         Towers in the Electroplating Industry as a Means
         of  Recycle and Waste Elimination", Technical
         Conference of  the  American Electroplaters1 Society,
         Minneapolis, Minnesota, June 18, 1973.
    
    (6U)  McLay, W.J., Corning Glass Company, Personal Communi-
         cation.
    
    (65)  Spatz, D.D., "Industrial Waste Processing With
         Reverse Osmosis",  osmonics.  Inc., Hopkins, Minnesota
         (August 1, 1971).
    
    (66)  Spatz, D.D., "Electroplating Waste Water Processing
         With Reverse Osmosis", Products Finishing, 36  (11),
         79-89 (August,  1972).
    
    (67)  Campbell, R.J.,  and  Emmerman, O.K., "Recycling of
         Water From Electroplating Wastes by Freezing
         Processes",  ASME Paper 72-PID-7 (March, 1972) .
                                   291
    

    -------
    (68)  Campbell,  R.J.,  and Emmerman,  D.K.,  "Freezing and
         Recycling  of Plating Rinse Water",  Industrial water
         Engineering, 9 (4), 38-39 (June/July, 1972).
    
    (69)  A.J.  Avila,  H.A. , Sauer, T.J.  Miller, and R.E.
         Jaeger,  Plating,  60 239 (1973) .
    
    (70)  Dvorin,  F.,  "Dialysis for Solution  Treatment in
         the Electroplating Industry",  Electroplating,
         57 (4),  52-54 +  62 (April, 1959).
    
    (71)  Ciancia, John, Plating 60, 1037  (1973).
    
    (72)  Communication with P. Peter Kovatis, Executive
         Director,  National Association of Metal  Finishers.
    
    (73)  "An Investigation of Techniques  for Removal of
         Chromium From Electroplating Wastes", Battelle,
         Columbus Laboratories Report on  Program  No.
         12010 EIE  to the Environmental Protection Agency
         and Metal  Finishers' Foundation  (March,  1971).
    
    (74)  Grieves, R., et  al.r "Dissolved-Air Ion  Flotation
         of Industrial Wastes.  Hexavalent Chromium",
         Proc. 23rd Industrial Waste Conference,  Purdue,
         University.  1968, p 154.
    
    (75)  Surfleet,  B., and Crowle, V.A.,  "Quantitative
         Recovery of  Metals from Dilure Solutions",
         Transactions of  the Institute of Electroplating,
         50, 227  (1972).
    
    (76)  Bennion, Douglas N., and Newman, John, "Electro-
         chemical Removal of Copper Ions  from Very Dilute
         Solutions",  Journal of Applied Electrochemistry,
         2,  113-122 (1972).
    
    (77)  Carlson, G.A., and Estep, E.E.,  "Porous  Cathode
         Cell  for Metals  Removal from Aqueous Solutions",
         from  Electrochemical Contributions  to Environmental
         Protection,  a symposium volume published by the
         Electrochemical  Society, Princeton,  New  Jersey,
         p 159.
    
    (78)  "Water Quality Criteria 1972," National Academy of
         Sciences and National Academy of Engineering for the
         Environmental Protection Agency, Washington, D.C.
         1972  'U.S. Government Printing Office Stock no.
         5501-00520).
                                  292
    

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                            SECTION XIV
                              GLOSSARY
    
    
    Acid_Dip.
    
    An  acidic  solution  for  activating  the workpiece surface
    prior to electroplating in an  acidic  solution,  especially
    after  the  workpiece  has  been  processed  in  an alkaline
    solution.
    Alkaline Cleaning
    
    Removal of grease or other foreign material from  a  surface
    by means of alkaline solutions.
    Anodizing
    
    The  production  of  a  protective oxide film on aluminum or
    other light  metals  by  passing  a  high  voltage  electric
    current through a bath in which the metal is suspended.  The
    metal  serves  as  the  anode.   The  bath  usually contains
    sulfuric, chromic, or oxalic acid.
    Automatic Plating
    
     (1)  full - plating in which the cathodes are  automatically
    conveyed through successive cleaning and plating tanks.
     (2)   semi  -  plating  in  which  the cathodes are conveyed
    automatically through only one plating tank.
    
    
    Barrel Plating
    
    Electroplating of workpieces in barrels  (bulk).
    
    
    BasisJ Metal_or Material
    
    That substance of which the workpieces  are  made  and  that
    receives  the electroplate and the treatments in preparation
    for plating.
    
    
    Batch Treatment
                                    293
    

    -------
    Treatment  of  electroplating  rinse  waters   collected    in
    adjacent tanks.  Water  is  not allowed to  leave the tank  till
    treatment is completed.
    
    
    
    Best_Available TechnglogY_Ec<)ngmicallY_Achievable
    
    Level of technology applicable to effluent limitations to  be
    achieved  by  July  1,  1983,  for  industrial discharges  to
    surface waters as defined  by Section 301(b)  (2)  (A)  of  the
    Act.
    
    Level of technology applicable to effluent limitations to  be
    achieved  by  July  1,  1977,  for  industrial discharges  to
    surface waters as defined  by Section 301 (b)  (1)  (A)  of  the
    Act.
    Bright Dip
    
    A solution used to produce a bright surface on a metal.
    
    
    Captiye^Operation
    
    Electroplating  facility  owned  and  operated  by  the same
    organization that manufacturers the workpieces.
    
    
    Chemical Brightening
    
    Process utilizing  an  addition  agent  that  leads  to  the
    formation of a bright plate, or that improves the brightness
    of the deposit.
    
    
    Chemical Etching
    
    To  dissolve  a part of the surface of a metal or all of the
    metal laminated to a base.
    
    
    ChemicalmMetaljColoring
    
    The production  of  desired  colors  on  metal  surfaces  by
    appropriate chemical or electrochemical action.
    
    
    Chemical^Polishing
                                    294
    

    -------
    The  improvement  in surface smoothness of a metal by simple
    immersion in a suitable solution.
    Chromatjzing
    
    To  treat  or  impregnate  with  a  chrornate  or  dichromate
    especially with potassium dichromate.
    
    
    Chrome-Pickle Process
    
    Forming  a  corrosion-resistant oxide film on the surface of
    magnesium-base metals by immersion in a bath  of  an  alkali
    bichromate.
    Closed-Loop. jEvaporation System
    
    A system used for the recovery of chemicals and water from a
    plating  line.   An  evaporator  concentrates  flow from the
    rinse water holding tank.  The concentrated  rinse  solution
    is  returned  to  the  plating  bath, and distilled water is
    returned to the final rinse tank.  The  system  is  designed
    for  recovering  100 percent of the chemicals, normally lost
    in dragout, for reuse in the plating process.
    Continuous_Treatment
    
    Chemical  waste  treatment  operating   uninterruptedly   as
    opposed  to  bath  treatment;  sometimes referred to as flow
    through treatment.
    Conversion Coating
    
    A coating produced by chemical or electrochemical  treatment
    of  a  metallic  surface  that  gives  a  superficial  layer
    containing a compound of the metal,  for  example,  chromate
    coatings on zinc and cadmium, oxide coatings on steel.
    Deoxidizing
    
    The  removal of an oxide film from an alloy such as aluminum
    oxide.
    Descaling
                                   295
    

    -------
    The  process  of  removing  scale  or  metallic  oxide  from
    metallic surfaces.
    The removal of smut, generally by chemical action.
    Dragin
    
    The  water  or  solution that adheres to the objects removed
    from a bath.
    Dragout
    
    The solution that adheres to  the  objects  removed  from  a
    bath,  more  preciously  defined  as  that solution which is
    carried past the edge of the tank.
    EDTA
    
    Abbreviation for ethylenediamine-tetraacetic acid.
    
    
    Effluent
    
    The waste water discharged from a point source to  navigable
    waters.
    
    
    Electrobrightening
    
    Electrolytic  brightening (electropolishing) produces smooth
    and bright surfaces by  electrochemical  action  similar  to
    those that result from chemical brightening.
                    Machining  (ECM)
    A  machining process whereby the part to be machined is made
    the anode and  a  shaped  cathode  is  maintained  in  close
    proximity  to  the  work.  Electrolyte is pumped between the
    electrodes and a potential  applied  with  the  result  that
    metal  is  rapidly  dissolved  from  the work in a selective
    manner and the shape produced on the work  complements  that
    of the cathode.
                                  296
    

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    Membrane  dialysis  under  the  influence  of direct current
    electricity.
    
    
    Electroless Plating
    
    Deposition of a metallic coating by  a  controlled  chemical
    reduction  that  is  catalyzed  by  the metal or alloy being
    deposited.
    
    
    Electropa jntj ng
    
    A coating process in which the  coating  is  formed  on  the
    workpiece  by making it anodic or cathodic in a bath that is
    generally an aqueous emulsion of the coating material.
    Electroplating
    
    The electrodeposition of an adherent metallic  coating  upon
    the  basis  metal  or material for the purpose of securing a
    surface with properties or dimensions different  from  those
    of the basis metal or material.
    Electroplating Process
    
    An   electroplating   process   includes   a  succession  of
    operations starting with  cleaning  in  alkaline  solutions,
    acid dipping to neutralize or acidify the wet surface of the
    parts,  followed  by  electroplating,  rinsing to remove the
    processing solution from the workpiece, and drying.
    Electrolytic corrosion process that increases the percentage
    of specular reflectance from a metallic surface.
    Electrostatic Precipitation
    
    Use of an electrostatic field for precipitating  or  rapidly
    removing  solid  or liquid particles from a gas in which the
    particles are carried in suspension.
                                    291
    

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    Heavy Metals
    
    Metals which can be precipitated by hydrogen sulfide in acid
    solution,  e.g.,  lead,  silver,  gold,  mercury,   bismuth,
    copper, nickel, iron, chromium, zinc, cadmium, and tin.
    A  method  of  coating  one  metal with another to provide a
    protective film.
    
    
    Hydrogen Embr ittlement
    
    Embrittlement of a metal or alloy caused  by  absorption  of
    hydrogen during a pickling, cleaning, or plating process,
    A  metallic  deposit  produced by a displacement reaction in
    which  one  metal  displaces  another  from  solution,   for
    example:
    
                 Fe * Cu-n-    Cu + Fe++
    
    
    Independe a t _O pe ration
    
    Job shop or contract shop in which electroplating is done on
    workpieces owned by the customer.
    
    
    Integrated Chemical Treatment
    
    A  waste  treatment method in which a chemical rinse tank is
    inserted in the plating line between the  process  tank  and
    the  water  rinse  tank.   The  chemical  rinse  solution is
    continuously circulated through the  tank  and  removes  the
    dragout while reacting chemicals with it.
    
    
    Ion-Flotation Technique
    
    Treatment   for   electroplating  rinse  waters  (containing
    chromium and cyanide)   in  which  ions  are  separated  from
    solutions by flotation.
                                     298
    

    -------
    Iridite Dip_Process
    
    Dipping  process  for  zinc  or  zinc  coated  objects  that
    deposits an adherent protective film that is a  chrome  gel,
    chrome oxide or hydrated chrome oxide compound.
    
    
    Phosphatizing
    
    Process  of  forming rust-resistant coating on iron or steel
    by immersing in a hot solution of acid manganese,  iron,  or
    zinc phosphate.
    Pickle
    
    An  acid  solution  used to remove oxides or other compounds
    related to the basis metal from its surface of  a  metal  by
    chemical or electrochemical action.
    Pickling
    
    The  removal  of  oxides  or  other compounds related to the
    basis metal from its surface by immersion in a pickle.
    Point,Source
    
    A single source of water discharge  such  as  an  individual
    plant.
    Precious Metals
    
    Gold, Silver, Platinum, etc.
    
    
    Back_Plating
    
    Electroplating of workpieces on racks.
    
    
    Reyerse_0smosis
    
    A  recovery  process in which the more concentrated solution
    is put under a pressure greater than the osmotic pressure to
    drive water across the membrane to the dilute  stream  while
    leaving behind the dissolved salts.
                                   299
    

    -------
    Rochell Salt
    
    Sodium potassium tartrate:  KNaC4H4O6 . 4H2O.
    
    
    Shgt_Peening
    
    Dry  abrasive  cleaning  of  metal surfaces by impacting the
    surfaces with high velocity steel shot.
    
    
    Sludge
    
    Residue in the  clarifier  of  a  chemical  waste  treatment
    process.
    
    
    Strike
    
    (1)    noun  -  a  thin  coating  of metal (usually less than
    0.0001 inch in thickness) to be followed by other  coatings.
    (2)    noun - a solution used to deposit a strike.  (3)  verb
    - a plate for a  short  time,  usually  at  a  high  initial
    current density.
    
    
    Stripping
    
    Removal of an electrodeposit by a chemical agent or reversed
    electrodeposition.
    
    
    Wgrkpiece
    
    The item to be electroplated.
                                      300
    

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                                                               Conversion Table
    co
    O
                    MULTIPLY (ENGLISH UNITS)
    
    
                           English Unit
    Abbreviation
        by                        TO OBTAIN  (METRIC  UNITS)
    
    
    Conversion       Abbreviation          Metric  Unit
    acre
    acre - feet
    British Thermal Unit
    British Thermal Unit/pound
    cubic feet/minute
    cubic feet/second
    cubic feet
    cubic feet
    cubic inches
    degree Fahrenheit
    feet
    gallon
    gallon/minute
    horsepower
    inches
    inches of mercury
    pounds
    million gallons/day
    mile
    pound/square inch (gauge)
    square feet
    square inches
    tons (short)
    yard
    ac
    ac ft
    BTU
    BTU/lb
    cfm
    cfs
    cu ft
    cu ft
    cu in
    °F
    ft
    gal
    gpm
    hp
    in
    in Hg
    Ib
    mgd
    mi
    psig
    sq ft
    sq in
    ton
    yd
    0.405
    1233.5
    0.252
    0.555
    0.028
    1.7
    0.028
    28.32
    16.39
    0.555(°F-32)*
    0.3048
    3.785
    0.0631
    0.7457
    2.54
    0.03342
    0.454
    3785
    1.609
    (0.06805 psig+D*
    0.0929
    6.452
    0.907
    0.9144
    ha
    cu m
    kg cal
    kg cal/kg
    cu m/ir.in
    cu m/min
    cu nv
    1
    cu cm
    °C
    m
    1
    I/sec
    kw
    cm
    atm
    kg
    cu m/day
    km
    atm
    sq m
    sq cm
    kkg
    m
    hectares
    cubic meters
    kilogram - calories
    kilogram calories/kilogram
    cubic meters/minute
    cubic meters/minute
    cubic meters
    liters
    cubic centimeters
    degree Centigrade
    meters
    liters
    liters/second
    kilowatts
    centimeters
    atmospheres
    kilograms
    cubic meters/day
    kilometer
    atmospheres (absolute)
    square meters
    square centimeters
    metric tor.s (1000 kilograms)
    meters
                    * Actual conversion, not a multiplier
    

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