DEVELOPMENT DOCUMENT

                  for

PROPOSED EFFLUENT LIMITATIONS GUIDELINES
    NEW SOURCE PERFORMANCE STANDARDS

                  and

         PRETREATMENT STANDARDS

                for the

     LEATHER TANNING AND FINISHING
         POINT SOURCE CATEGORY
           Douglas M. Costle
             Admini s tr ator

           Thomas C. Jo r ling
      Assistant Administrator for
       Water and Waste Management

             Swep T. Davis
   Deputy Assistant Administrator for
      Water Planning and Standards
           Robert B. Schaffer
 Director, Effluent Guidelines Division

           Donald F. Anderson
         Senior Project Officer

            Barbara G. Ernst
          Technical Assistant

               July 1979

      Effluent Guidelines Divison
  Office of Water and Waste Management
  U.S. Environmental Protection Agency
        Washington, D.C.  20460

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Section

   I

  II

 III

  IV

   V

  VI

 VII

VIII

  IX
   X
  XI
 XII

XIII

 XIV

  XV

 XVI



XVII
                TABLE OF CONTENTS

                    Title

CONCLUSIONS

RECOMMENDATIONS

INTRODUCTION

INDUSTRY SUBCATEGORIZATION

WATER USE AND WASTE CHARACTERISTICS

SELECTION OF POLLUTANT PARAMETERS

CONTROL AND TREATMENT TECHNOLOGY

COST, ENERGY, AND NON-WATER QUALITY ASPECTS

EFFLUENT REDUCTION ATTAINABLE THROUGH THE
 APPLICATION OF THE BEST PRACTICABLE  CONTROL
 TECHNOLOGY CURRENTLY AVAILABLE—
 EFFLUENT LIMITATIONS GUIDELINES

EFFLUENT REDUCTION ATTAINABLE THROUGH THE
 APPLICATION OF THE BEST AVAILABLE TECHNOLOGY
 ECONOMICALLY ACHIEVABLE—
 EFFLUENT LIMITATIONS GUIDELINES

EFFLUENT REDUCTION ATTAINABLE THROUGH THE
 APPLICATION OF THE BEST CONVENTIONAL
 POLLUTANT CONTROL TECHNOLOGY—
 EFFLUENT LIMITATIONS GUIDELINES

NEW SOURCE PERFORMANCE STANDARDS

PRETREATMENT STANDARDS

MONITORING

ACKNOWLEDGEMENTS

REFERENCES

SUPPLEMENTAL BIBLIOGRAPHY

GLOSSARY

APPENDIX A
Page

  1

  5

  7

 37

 47

 87

121

211
                                                              255
                                                              269
303

311

313

331

335

337

347

359

371
                                  111

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APPENDIX B                                         375



APPENDIX C                                         377



APPENDIX D                                         379




APPENDIX E                                         38 -j

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                            LIST OF TABLES

Number                        Title                          Page

1         Recommended List of Toxic Pollutants                13

2         Distribution of Plant Sampling                      20

3         Production and Marketing Trends in the Leather
           Tanning and Finishing Industry                     23

4         Category Comparison by Principal Processes          40

5         Plant Characteristics of Tanneries Sampled
           for Toxic Pollutants                               57

6         Raw Waste Characteristics for Subcategory 1 -
           Hair Pulp, Chrome Tan, Retan - Wet Finish          60

6A        Toxic Pollutant Characteristics of Raw Waste-
           water, (Subcategory 1)                             61

7         Raw Waste Characteristics for Subcategory 2 -
           Hair Save, Chrome Tan, Retan - Wet Finish          63

7A        Toxic Pollutant Characteristics of Raw Waste-
           water, (Subcategory 2)                             64

8         Raw Waste Characteristics for Subcategory 3 -
           Hair Save, Nonchrome tan, Retan - Wet Finish       67

8A        Toxic Pollutant Characteristics of Raw Waste-
           water, (Subcategory 3)                             68

9         Raw Waste Characteristics for Subcategory 4 -
           Retan - Wet Finish                                 70

9A        Toxic Pollutant Characteristics of Raw Waste-
           water, (Subcategory 4)                             71

10        Raw Waste Characteristics for Subcategory 5-
           No Beamhouse                                       73

10A       Toxic Pollutant Characteristics of Raw Waste-
           water, (Subcategory 5)                             74

11        Raw Waste Characteristics for Subcategory 6 -
           Through-the-Blue                                   76

11A       Toxic Pollutant Characteristics of Raw Waste-
           water, (Subcategory 6)                             77

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 12        Raw Waste Characteristics  for Subcategory 7 -
           Shearlings                                         79

 12A       Toxic Pollutant Characteristics of Raw Waste-
           water f  (Subcategory  7)                             80

 13        Summary of Subcategory Flows                        82

 1*        Comparison of Winter/Summer Raw Waste
           Characteristics                                    83

 15        Hourly Raw Waste Data for  a Single Cattlehide
           Tannery  (Subcategory 1)                            84

 16        Number of Different Toxic  Pollutants Detected
           per Subcategory                                    85

 17        Characteristics of Toxic Pollutants detected during
           the Sampling Program                               95

 18        Soaking of Wet Salted Prefleshed Hides with con-
           tinuous Rinsing and Batch Washing                 128

 19        Proportioned Flows and Pollutant Loads for Beam-
           house and Tanyard/Retan/Wet Finish Operations     132

 20        Analysis of Lime Liquors                           134

 21        In-plant Process Changes Indicated on Question-
           naire from total of 46 Leather Tanneries          148

 22        Waste Stream Segregation in Leather Tanneries
           as Reported in Questionnaires from 46 plants      150

 23        Performance of Flue Gas Carbonation and
           Chemical Coagulation                              155

 24        Performance of Plain Sedimentation                 161

 25        Pollutant Removals by Plain Sedimentation
           at Tannery No.  237                                162

 26        Performance of Coagulation Sedimentation           164

27        Performance Characteristics of Trickling
           Filter Treatment for Tannery Wastewaters          167

28        Aerobic Lagoon Performance as a Function
           of Season                                         169
                                  VI

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29        Carrousel System Performance for Leather
           Tanning Wastewater                                173

30        Treatment of Wastewater with Chappel Process
           at Tannery No.  247                                180

31        Performance Summary of the Chappel Process
           Treating Tannery Wastewater                       181

32.       Incremental Increase in Summary of Performance of
           Activated Sludge by Powdered Activated Carbon
           Addition                                          189

33.       Summary of Multi-Media Filtration Performance      190

34        Adsorption Treatment Systems                       194

35        Summary of Effectiveness of Candidate
           Technologies                                      206

36        Toxic Pollutant  Treatment Effectiveness from
           Three Day Toxics Sampling Program                 208

37        Industry Estimates for Land Disposal of
           Solid Wastes                                      244

38        Disposal Sites Utilized                            246

39        "Typical" Sludge Characteristics                   247

40        BPT Effluent Limitations                           264

41        Level of Treatment - Waste Stream Composition      273

42        Summary of Reduced Subcategory Flows for
           BAT                                               281

43        Capital Costs for Each Level of Treatment          295

44        Operation and Maintenance Costs for Each
           Level of Treatment                                296

45        BAT Effluent Limitations                           298

46        Summary of BCT Cost-Reasonableness Test
           by Subcategory and Technology Option              305

47        BCT Effluent Limitations                           306

48        PSES Effluent Limitations                          323

49        PSNS Effluent Limitations                          327
                                 VII

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                           LIST OF FIGURES

Number                        Title                          Page

1         General Process Flowsheet for Leather               24
           Tanning and Finishing Industry

2         Product and Wastewater Flow for Generalized
           Leather Tanning and Finishing Plants               48

3         COD to BOD5. Ratio in Tannery Secondary
           Effluents                                         176

4         Technology Schematic for In-Plant Control and
           Preliminary Treatment  (Subcategories 1/2)         200

5         Technology Schematic for In-Plant Control and
           Preliminary Treatment  (Subcategory 3)             201

6         Technology Schematic for In-Plant Control
           (Subcategory 4)                                   202

7         Technology Schematic for In-Plant Control
           (Subcategories 5,7)                               203

8         Technology Schematic for In-Plant Control
           and Preliminary Treatment  (Subcategory 6)         204

9         Technology Schematic for End-of-Pipe Waste-
           water Treatment for all Subcategories             205

10        Capital Cost Curve for Stream Segregation          214

11        Operation and Maintenance Cost Curve for
           Stream Segregation                                215

12        Capital Cost Curve for Sulfide Oxidation           217

13        Operation and Maintenance Cost Curve for
           Sulfide Oxidation and Ammonia Substitution        218

14        Capital Cost Curve for Flue Gas Handling
           Equipment                                         220

15        Capital Cost Curve for Flue Gas Carbonation
           Clarifier                                         221

16        Operation and Maintenance Cost Curve for Flue
           Gas Carbonation                                   222
                                  IX

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 17         Capital  Cost  Curve  for Equalization                 223

 18         Capital  Cost  Curve  for Coagulation-Sedimentation    225

 19         Annual Manhour Requirements  for  Coagulation-
            Sedimentation                                      226

 20         Operation and Maintenance Cost Curve  for Equali-
            zation  and Coagulation-Sedimentation              227

 21         Capital  Cost  Curve  for Activated Sludge
            Secondary Treatment                                228

 22         Operation and Maintenance Cost Curve  for
            Activated Sludge Secondary  Treatment              229

 23         Operation and Maintenance Cost Curve  for
            Upgraded Secondary Treatment                       231

 24         Capital  Cost  Curve for Multi-Media Filtration       232

 25         Operation and Maintenance Cost Curve  for
            Multi-Media  Filtration                            233

 26         Capital  Cost  Curve for Activated Carbon
            Column  System                                      235

 27         Operation and Maintenance Cost Curve  for
            Activated Carbon Column System                     236

 28         Capital  Cost  Curve for  Chappel Process              237

 29        Operation and Maintenance Cost Curve  for
            Chappel Process                                    239

 30        Capital Cost Curve for  Sludge Dewatering            240

31        Operation and Maintenance Cost Curve  for
            Sludge Dewatering                                 241

32        Average Monthly Final Effluent Concentrations
          of BOO5,  TSS,  and Chromium (Total)  from an
          Activated Sludge System in a Northern Climate
           (Hartland,  Maine POTW)                              259

33        Average Monthly BOD5 and TSS Effluent
           Concentrations from an Activated Sludge
           System in  a  Northern Climate
           (Berwick, Maine POTW)                               261
                                  x

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34        Average Monthly Total Chromium Effluent
           Concentration from an Activated Sludge
           System in a Northern Climate
          (Berwick, Maine POTW)                              262

35        Average Monthly Final Effluent Concentrations
          of BOD5 and TSS for the Carrousel Activated
          Sludge System at Tannery #253                      292

36        Average Monthly final Effluent Concentrations
          of TKN, Ammonia, Oil and Grease, and Total
          Chromium for the Carrousel Activated Sludge
          System at Tannery #253                             293
                                  XI

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                               SECTION  I

                             CONCLUSIONS

The leather  tanning  and   finishing   industry  characteristically   is
family-owned,  not  very  progressive  or profitable, and dominated  by
small plants employing less than  100 people.  There are  an  estimated
188  leather  tanning  and  finishing plants in the United States today
comprised  of  170  dischargers   to  publicly  owned  treatment  works
(indirect  dischargers)  and   18  dischargers  to  waters  of the U.S.
(direct dischargers).  Total industry  flow is approximately 52 million
gallons daily  (MGD), of which  47  MGD are discharged to POTWs and 5 MGD
are discharged directly to  navigable waters.

For  the  purpose   of  establishing  wastewater  effluent  limitations
guidelines  and  standards  of  performance for new sources, the Leather
Tanning and Finishing Point Source Category has been subcategorized  as
follows:

1.   Hair Pulp-Chrome Tan-Retan-Wet Finish
2.   Hair Save-Chrome Tan-Retan-Wet Finish
3.   Hair Save-Nonchrome Tan-Retan-Wet Finish
4.   Retan-Wet Finish
5.   No Beamhouse
6.   Through-the-Blue
7.   Shearling.

The primary criteria  for   subcategorizing  the  leather  tanning  and
finishing   industry  were  the  type  or  condition  of  animal  hide
processed, method of hair removal, type of  tanning  agent  used,  and
extent  of  finishing  performed.   Plant  size,  age,  and  location,
wastewater characteristics, and water usage were also considered.

The most significant pollutants and pollutant parameters  detected   in
the  industry's  wastewaters  in terms of occurrence and concentration
include:   the conventional  and proposed conventional pollutants  BOD5,
TSS,  pH,   COD, and oil and grease;  and the nonconventional pollutants
ammonia,  total Kjeldahl nitrogen  (TKN), and  sulfide.    The  following
toxic  pollutants  were  found  in  treated effluents  at more than two
plants above the nominal limits of detection:

     2,4,6-trichlorophenol
     chloroform
     1,2-dichlorobenzene
     1,4-dichlorobenzene
     ethylbenzene
     methylene chloride (dichloromethane)
     naphthalene
     pentachlorophenol
     phenol

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     bis(2-ethylhexyl) phthalate
     toluene
     chromium
     copper
     cyanide
     lead
     nickel
     zinc

A total of 37 toxic pollutants were detected in raw  waste  discharges
of which 17 were also detected in biologically treated effluents.

The  Agency  concludes  that  the  best practicable control technology
currently available  (BPT) is based upon  the  performance  of  primary
treatment    (coagulation-sedimentation)   and  "secondary"  biological
treatment  (extended aeration activated sludge) as practiced  at  plant
No. 47  (subcategory No. 3) and at the Berwick, Maine POTW which treats
more   than   90  percent  tannery  wastewater   (subcategory  No.  4).
Treatment systems at plant No. 253  (subcategory No. 7), a plant in the
Netherlands  (subcategory No. 1), and the Hartland, Maine POTW treating
90  percent  tannery  wastewater   (subcategory  No.  1)  support  this
conclusion  because  the  performance  of  these  systems  equaled  or
surpassed the performance of plant No. 47 and the Berwick  POTW.   The
Agency  also  concludes  that  the  balance  of the plants with direct
discharge have inadequate treatment systems and must  be  upgraded  to
achieve  effluent  limitations  based upon BPT performance transferred
from subcategories within the leather tanning and finishing industry.

The pollutant parameters regulated by the  proposed  best  practicable
technology   (BPT) are BOD5, TSS, oil and grease,  (total)  chromium, and
pH.

The Agency concludes that the best available  technology  economically
achievable   (BAT)  builds  on BPT technology with in-plant control,and
pretreatment, and upgraded biological treatment by powdered  activated
carbon  addition,  and  multi-media  filtration.   Plant  No. 247 (now
closed) employed physical/chemical treatment to  achieve  an  effluent
quality  far better than required by BAT.  The activated sludge system
at plant No.  253 has achieved BAT effluent quality  for  some  of  the
regulated  pollutant  parameters for substantial periods of time.  The
balance of the plants with direct discharge have inadequate  treatment
systems  in place and technology and performance transfer is necessary
to achieve BAT effluent limitations.

The pollutants regulated by the  proposed  best  available  technology
economically achievable (BAT)  and the new source performance standards
(NSPS)   are  BOD5, COD, TSS, oil and grease, TKN, ammonia, sulfide and
pH, and the toxic pollutants (total)  chromium and (total)  phenol.   No
effluent   limitations   have   been  proposed  for  any  other  toxic
pollutants.  The control of toxics other  than  chromium  and  phenol.

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which  were found in significant concentrations in tannery wastewater,
will be regulated by  placing  numerical  limitations  on  "indicator"
pollutantsr  including  BOD5>,  COD, TSS, oil and grease, TKN, ammonia,
(total)  chromium,  and  (total)  phenol.   EPA  has  concluded   from
available  data that when the indicator pollutants are controlled, the
concentrations of toxic pollutants are significantly lower  than  when
the  indicator  pollutants  were  present in high concentrations.  The
Agency concludes from  this  data  that  control  of  the  "indicator"
pollutants is necessary to ensure the control of toxic pollutants.

The  Agency  concludes  that plants with indirect discharge contribute
substantial quantities of organic compounds and heavy metals, the most
important  of  which  is  chromium,  to  the  contamination  of  large
quantities  of  POTW  sludges.  In addition, the Agency concludes that
the high concentrations  of  nitrogen   (particulary  ammonia)  in  raw
wastewater  pass  through  POTW  largely  untreated, and that the high
concentrations of hydrogen sulfide in raw wastewaters can and do cause
severe  odor  and  health   hazard   problems.    In-plant   controls,
pretreatment  of segregated streams, and primary treatment of combined
streams is the technology basis of pretreatment standards for existing
sources (PSES) to control  the  discharge  of  toxic  pollutants,  and
ammonia and sulfides.  This level of control will increase POTW sludge
disposal  alternatives, improve POTW effluent quality, and essentially
eliminate odor and health hazard problems.  The Agency concludes  that
this  level  of  control  recognizes  limitations on existing interior
plant space and adjacent land.  Most plants will find it necessary  to
install  a  large  portion of these in-plant controls and pretreatment
technologies to achieve PSES limitations.

The Agency concludes  that  pretreatment  standards  for  new  sources
(PSNS)   should  be  based  upon the same technology used for PSES plus
physical/chemical treatment to achieve BAT levels of control for toxic
pollutants.  The Agency concluded  this  level  of  control  would  be
necessary  because  POTW  effluent quality which incorporates PSES may
not be the same as the effluent quality based  on  BAT  for  a  direct
discharger.

The  pollutants  regulated  by the proposed pretreatment standards for
existing sources (PSES) are total chromium, ammonia, and sulfides.  In
addition  to  limitations   for   these   pollutants,   the   proposed
pretreatment standards for new sources  (PSNS)  also include limitations
on the pollutants regulated by BAT,

The  Agency  concludes  that  the  total  investment  cost incurred by
existing sources, both direct and  indirect  dischargers,  to  achieve
these  effluent  limitations guidelines  (BPT and BAT) and pretreatment
standards (PSES)  is $65 million, with total  annualized  cost  of  $34
million.   A total of approximately 300,000 Ibs/yr of chromium will be
removed by compliance with BAT effluent limitations, and more  than  2
million  Ibs/yr  of  chromium  will  be  removed  from POTW sludges by

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compliance with PSES.  In addition, approximately 59 million Ibs/yr of
conventional pollutants and  2.3  million  Ibs/yr  of  nonconventional
pollutants  will  be  removed  by  BAT;  and  172  million  Ibs/yr  of
conventional pollutants and  5.7  million  Ibs/yr  of  nonconventional
pollutants will be removed by compliance with PSES.

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                              SECTION II

                           RECOMMENDATIONS

Proposed  effluent  limitations representative of the best practicable
control  technologies  currently  available   (BPT)  are   based   upon
performance  characteristics  of  primary  treatment  and  "secondary"
biological treatment  (high solids extended aeration activated sludge).
Numerical limitations  (Ibs/1,000 Ibs of raw material) are proposed for
BOD5, TSS, oil and grease, (total) chromium, and pH, and apply to  all
seven subcategories.  See. Section IX for the mass limitations.

Proposed  effluent  limitations  for  the  best  available  technolgoy
economically achievable are based upon BPT  technology  plus  in-plant
control,  pretreatment,  upgraded  biological  treatment  by  powdered
activated  carbon   (PAC)    addition,   and   multi-media   filtration.
Numerical limitations  (lbs/1,000 Ibs of raw material) are proposed for
three  non-toxic, non-conventional pollutants: total Kjeldahl nitrogen
(TKN),  ammonia,  and  sulfide;  TKN  and  ammonia   also   serve   as
"indicators"  for  the removal of toxic pollutants.  Other "indicator"
pollutants for which limitations are proposed are BOD5, COD, TSS,  oil
and  grease,  total  chromium,  and  total  phenol.   The  only  toxic
pollutants expressly controlled for direct  dischargers  are  chromium
and phenol.  See Section X for the mass limitations.

The BAT "indicator" limitations on conventional pollutants have passed
the  cost  reasonableness  test   (POTW  cost comparison) and have been
designated as the proposed  BCT  limitations  (lbs/1,000  Ibs  of  raw
material)  as well.

The  proposed new source performance standards are the same as BAT for
the same regulated parameters.

Proposed pretreatment standards for existing sources (PSES)  are  based
on  in-plant  control  and  pretreatment  technologies to regulate pH,
chromium,  sulfide,  and  ammonia.   Limitations  are  expressed  on  a
concentration  basis   (mg/1), while mass limitations (lbs/1,000 Ibs of
raw material) are also included as guidance for POTWs which  may  find
it  necessary  to  control the mass of pollutants introduced by system
users.

Proposed pretreatment standards for new sources (PSNS)   are  based  on
in-plant  control  and pretreatment technology, plus physical/chemical
treatment to achieve effluent quality equal to that required  by  BAT.
Limitations  are expressed on a concentration basis  (mg/1),  while mass
limitations  (lbs/1,000 Ibs of  raw  material)   are  also  included  as
guidance  for POTWs which may find it necessary to control the mass of
pollutants introduced by system users.

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                             SECTION III

                             INTRODUCTION

PREFACE

On July 2,  1979, the United  States  Environmental  Protection  Agency
 (EPA)  proposed  regulations  to  control  water  pollution by leather
tanning and finishing plants.  See 44 FR 38746.  The purpose of  those
regulations   is   to  provide  effluent  limitations  guidelines  and
standards of performance under the Clean Water Act.  To  promote  that
purpose,    the   proposed   regulations   also   include   monitoring
requirements.

This document highlights EPA's study of the industry and explains  the
technical rationale for the proposed regulations.

PURPOSE AND AUTHORITY

The Federal Water Pollution Control Act Amendments of 1972 established
a  comprehensive  program  to  "restore  and  maintain  the  chemical,
physical, and biological integrity of the  Nation's  waters."  Section
101 (a).   By  July  1,  1977,  existing  industrial  dischargers  were
required to achieve "effluent limitations requiring the application of
the best practicable control technology currently available"   ("BPT"),
Section  301 (b) (1) (A);  and  by  July  1, 1983, these dischargers were
required to achieve "effluent limitations requiring 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"   ("BAT"),   Section
301(b)  (2) (A).   New  industrial  direct  dischargers  were required to
comply with Section 306 new  source  performance  standards  ("NSPS"),
based  on best available demonstrated technology; and new and existing
dischargers to publicly owned treatment works ("POTWs")  were  subject
to  pretreatment  standards  under Sections 307(b)  and (c)  of the Act.
While the requirements for direct dischargers were to be  incorporated
into  National  Pollutant Discharge Elimination System (NPDES)  permits
issued under Section 402 of the Act, pretreatment standards were  made
enforceable   directly   against   dischargers   to   POTWs  (indirect
dischargers).

Although section 402 (a) (1)  of the 1972 Act authorized the  setting  of
requirements  for direct dischargers on a case-by-case basis, Congress
intended that for the most part control requirements would be based on
regulations promulgated by the Administrator of EPA.   Section  304(b)
of  the  Act  required  the  Administrator  to  promulgate regulations
providing guidelines for effluent limitations setting forth the degree
of effluent reduction attainable through the application  of  BPT  and
BAT.    Moreover,   Sections  304 (c)   and  306  of  the  Act  required
promulgation of regulations for NSPS,  and Sections 304 (f),  307(b),  and

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307 (c)  required  promulgation   of   regulations   for   pretreatment
standards.   In  addition to these regulations for designated industry
categories, Section 307(a) of the Act required  the  Administrator  to
promulgate  effluent  standards applicable to all dischargers of toxic
pollutants.   Finally,  Section  501 (a)  of  the  Act  authorized  the
Administrator  to  prescribe  any additional regulations "necessary to
carry out his functions" under the Act.

The EPA was unable to promulgate many  of  these  regulations  by  the
dates  contained  in  the  Act.   In  1976,  EPA  was  sued by several
environmental groups, and in settlement of this lawsuit  EPA  and  the
plaintiffs executed a "Settlement Agreement" which was approved by the
Court.  This Agreement required EPA to develop a program and adhere to
a  schedule  for  promulgating  for  21  major industries BAT effluent
limitations  guidelines,  pretreatment  standards,  and   new   source
performance  standards  for  65  "priority"  pollutants and classes of
pollutants.  See Natural Resources Defense Council, Inc. v.  Train,  8
ERC 2120  (D.D.C. 1976), modified March 9, 1979.

On  December  27,  1977, the President signed into law the Clean Water
Act of 1977.  Although this law makes several important changes in the
Federal water pollution control program, its most significant  feature
is  its  incorporation  of  several  of  the  basic  elements  of  the
Settlement Agreement program for toxic  pollution  control.   Sections
301(b) (2)  (A)  and  301(b)  (2) (C) of the Act now require the achievement
by July 1, 1984 of effluent limitations requiring application  of  BAT
for  "toxic"  pollutants,   including  the 65 "priority" pollutants and
classes of pollutants which Congress declared  "toxic"  under  Section
307 (a)   of   the  Act.   Likewise,  EPA's  programs  for  new  source
performance  standards  and  pretreatment  standards  are  now   aimed
principally  at toxic pollutant controls.  Moreover, to strengthen the
toxics control program. Section  304 (e)  of  the  Act  authorizes  the
Administrator  to  prescribe  "best  management practices" ("BMPs") to
prevent the release of toxic and hazardous pollutants from plant  site
runoff,  spillage or leaks, sludge or waste disposal, and drainage from
raw   material   storage   associated   with,  or  ancillary  to,  the
manufacturing or treatment process.

In keeping with its emphasis on toxic pollutants, the Clean Water  Act
of  1977  also  revises  the control program for non-toxic pollutants.
Instead of BAT for "conventional" pollutants identified under  Section
304 (a) (4)   (including  biochemical  oxygen  demand,  suspended solids,
fecal  coliform  and  pH),  the  new  Section  301 (b) (2) (E)    requires
achievement  by  July  1,  1984, of "effluent limitations requiring the
application of the best  conventional  pollutant  control  technology"
("BCT").   The  factors  considered  in  assessing BCT for an industry
include the costs of  attaining  a  reduction  in  effluents  and  the
effluent reduction benefits derived compared to the costs and effluent
reduction  benefits  from  the  discharge  of publicly owned treatment
works  (Section   304(b) (4) (B)).    For   non-toxic,   nonconventional

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pollutants. Sections  301 (b) (2) (A) and  (b) (2) (F)  require achievement of
BAT  effluent limitations within three years after their establishment
or July  1,  1984, whichever  is  later, but not later than July  1,  1987.

The purpose of these  proposed regulations  is  to  provide   effluent
limitations  guidelines  for BPTr BAT, and BCT,  and to establish NSPS,
pretreatment standards for  existing sources  (PSES),  and  pretreatment
standards   for  new sources (PSNS), under Sections 301, 304,  306,  307,
and 501  of the Clean  Water  Act.  To promote this purpose, the proposed
regulations also establish  monitoring requirements under  Section  308
of the Act.

SUMMARY  OF METHODOLOGY

The  effluent  limitations  and pretreatment standards set forth herein
were developed in the following  manner.   The  original  development
document   (1974)  and the  appendices to that document were  acquired.
The organization that prepared  the  original   "draft"  document  was
included  on  the  study  team so that the venefit of their experience
could  be  obtained   and  the  incorporation  of  existing  data   and
information on the tanning  industry would be facilitated.

First,  EPA  studied  the leather tanning industry to determine whether
differences in raw materials,  final products, manufacturing processes,
equipment,  age  and  size  of   plants,   water   usage,   wastewater
constituents,  or  other  factors required the development of separate
effluent limitations  and  standards  for  different  segments  of  the
industry.   This  study  included  the identification of raw  waste and
treated effluent  characteristics,  including:   1)   the  sources  and
volume  of  water  used,  the  processes  employed, and the sources of
pollutants and wastewaters  in  the plant,  and 2)  the  constituents  of
wastewaters,  including  toxic  pollutants.   EPA  then identified the
constituents of wastewaters which should be  considered  for  effluent
limitations guidelines and  standards of performance, and statistically
analyzed raw waste constituents.

Next,    EPA   identified    several   distinct  control  and   treatment
technologies, including both in-plant and end-of-process technologies,
which are in use or capable of being used in the leather  tanning  and
finishing  industry.  The Agency compiled and analyzed historical data
and newly generated data on the effluent quality  resulting   from  the
application   of  these  technologies.   The  long  term  performance,
operational limitations, and reliability of each of the treatment  and
control   technologies   were   also  identified.   In  addition,  EPA
considered  the  non-water  quality  environmental  impacts  of  these
technologies,   including   impacts   on   air  quality,  solid  waste
generation, water scarcity, and energy requirements.

The Agency then estimated the costs  of  each  control  and  treatment
technology  from  unit  cost  curves developed by standard engineering

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analysis as  applied  to  leather  tanning  and  finishing  wastewater
characteristics.   EPA  derived  unit  process  costs from model plant
characteristics   (production  and  flow)  applied  to  each  treatment
process  unit  cost  curve   (i.e.,  primary coagulation-sedimentation,
activated sludge, multi-media filtration, etc.).  These  unit  process
costs  were  added to yield total cost at each treatment level.  After
confirming the reasonableness of this  methodology  by  comparing  EPA
cost estimates to treatment system costs supplied by the industry, the
Agency evaluated the economic impacts of these costs.

Upon  consideration  of  these factors, as more fully described below,
EPA identified various control and treatment technologies as BPT, BCT,
BAT, PSES, PSNS, and NSPS.  The proposed regulations, however, do  not
require  the  installation of any particular technology.  Rather, they
require achievement of  effluent  limitations  representative  of  the
proper operation of these technologies or equivalent technologies.

The  effluent  limitations for BPT, BCT, BAT and NSPS are expressed as
mass limitations  (lbs/1000 Ibs raw material)   and  are  calculated  by
multiplying  three  figures:   (1)  effluent concentrations determined
from analysis of control technology performance data,   (2)   wastewater
flow  for  each subcategory, and  (3)  any relevant process or treatment
variability factor (e.g., maximum month vs. maximum day).  This  basic
calculation  was  performed  for each regulated pollutant or pollutant
parameter for each subcategory of the industry.  Effluent  limitations
for  PSES  and  PSNS  are  expressed  as  allowable  concentrations in
milligrams per liter (mg/1).  For POTWs which may wish to impose  mass
limitations,  the  proposed regulations provide guidance on equivalent
mass limitations.

Data and Information Gathering Program

In addition to the 1974 study, EPA gathered the  following  additional
data for the proposed BPT, BAT, BCT,  NSPS, PSES, and PSNS:

     1.   Through  the  Tanners1   Council  of   America   (TCA),   EPA
          distributed  one-page surveys and detailed questionnaires to
          about 301  addresses  of  tanneries,  finishers,   and  sales
          offices  to obtain information on specific plant situations.
          It was jointly agreed at the outset of the study by EPA  and
          the  TCA  that authority of Section 308 of the Act would not
          be used to gather  technical  information  to  support  this
          effort,  except  as  a  last resort in obtaining critical or
          proprietary information.  EPA received survey responses from
          116 tanneries and questionnaires from 89 tanneries.

     2.   EPA contacted 50 municipalities to  collect  information  on
          city   ordinance   wastewater   limitations,   reasons   for
          limitations,  wastewater problems and plans for dealing  with
          the  problems.   Supplementary  wastewater  data  for  local


                                 10

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           tanneries  and municipal   POTW   performance  data  were   also
           requested.   The  Agency  obtained   extensive   data  for  four
           POTWs  which treat primarily  leather  tanning   and  finishing
           wastewater.    Many    POTWs,    however,  could not  provide
           extensive  data for parameters other  than flow,  pH, BODS, and
           TSS.                                                  -

      3.    During  field  visits  to 50   tanneries,   EPA   collected
           information   on   plant   operations,   sites,   practices,
           processes, equipment,  management concerns and  attitudes, and
           wastewater and production data; 22 of the visited  tanneries
           were sampled for wastewater  constituents.  Tanneries visited
           and/or  sampled   included   facilities  representing   most
           industrial situations  and operations,  including  plants  of
           different  sizes, ages, and locations.

      U.    NPDES  permit data and  background information on a number  of
           tanneries  were obtained  from EPA regional offices.  Permits
           included information on   the  tannery  and  waste  treatment
           facilities  and  the   discharge  standards  and schedule for
           compliance being set at the  present  time.

      5.    The Agency received engineering studies and reports on waste
           treatment  facilities for  several tanneries.   These  reports
           included  dimensions   and descriptions  of  the facilities,
           operating  practices,  data  on   wastewater   quality   and
           quantity,   waste   treatment  design  basis  and  criteria,
           treatment system problems, and cost  estimates for wastewater
           control and treatment  facilities.

      6.    EPA  also  contacted   state  pollution  control  offices  to
           request available data and information on tannery wastewater
           problems and plans for dealing with these problems.

In  response  to  the  Clean  Water  Act of 1977 and the EPA -  Natural
Resources Defense Council (NRDC)  Settlement Agreement (NRDC v.   Train
8  ERC  2120  (D.D.C.  1976),   the  updated  study  of "this  industry
emphasizes  the  evaluation  of  65  classes  of   potentially    toxic
pollutants declared toxic under  section 307 (a)  of the Act.  This group
of   pollutants  and  classes   of  pollutants,   potentially  including
thousands of specific compounds,  was eventually lengthened to  a  list
of 129 priority pollutants  (Table 1) which served as the basis  for the
proposed  BAT,   new  source performance  standards,   and pretreatment
standards for new and existing sources.

     1.   In order to obtain information  and  data  on  the priority
          pollutants,  wastewater control  and treatment practices,  and
          in-plant process  changes,  EPA mailed  questionnaires   to  all
          domestic  tanners and  to the industry's  chemical  suppliers.
          The suppliers were unable to  provide  significant information
          on the  priority pollutant content  of  their  products   due   to


                                 11

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          their   apparently   limited   knowledge   of  the  chemical
          constituents   of   their   products.    Forty-six   tannery
          questionnaires  were  returned,  sixteen  of  which included
          detailed information on chemical usage.

     2.   Under Section 308 of the Act, EPA also conducted an economic
          survey of the industry.  Questionnaires were mailed  to  the
          188  domestic tanneries requesting production costs, balance
          sheet and income data,  and  costs  for  existing  pollution
          abatement   systems.    Sixteen   of   the  eighteen  direct
          dischargers  and  120  of  the  170   indirect   dischargers
          responded.

In  order  to determine the toxic pollutant content of leather tannery
wastewater, the Agency developed a two phase wastewater  sampling  and
analysis  program.   Twenty-two tanneries and two POTWs were involved,
the  latter  with  substantial  tannery  wastewater  flows.   A  table
describing  the  tanneries  in  this  sampling  program is provided in
Section V.   The  original  leather  tanning  study  had  divided  the
industry into six subcategories.  Phase one of the wastewater analysis
program  sampled  one  plant  in  each  of these subcategories for the
presence of  toxic  pollutants.   During  the  second  phase  of  this
program, the industry was re-divided into seven subcategories; sixteen
representative  plants  and  two  POTWs were sampled for quantities of
priority pollutants.  A distribution of plant sampling  is  summarized
in Table 2.  A. summary of the special wastewater sampling and analysis
methods is included in Appendix A of this document.

The  analytical  methods used for toxic pollutant analyses are capable
of detecting the presence of compounds generally at  levels  of  parts
per billion.  The analytical results involve the terminology "level of
detection".    When   results   appear  to  indicate  the  absence  of
pollutants, they are in fact, simply reporting the lack of  detection.
This  is  because  the analytical procedures are limited to a specific
lower limit of concentration detectable  for  each  compound;  thus  a
wastewater  concentration  for  a  compound  below that lower level is
reported as  not  detected  (ND).   This  produces  results  on  toxic
pollutants  across  waste treatment systems that would be questionable
for standard pollutants, i.e., a toxic pollutant may not  be  detected
in  the raw wastewater but show up in the final effluent.  This occurs
when sample preparation requires substantial  dilution  for  injection
into the analytical equipment.  This dilution may reduce the pollutant
concentration to a level below the detection limit.
The leather tanning and finishing industry is included within the U.S.
Department  of  Commerce,  Bureau  of  the  Census Standard Industrial
Classification (SIC)  3100, Leather and Leather Products.  The part  of
the  industry  addressed  in  this  report  is identified as SIC 3111,
Leather Tanning and Finishing.
                                 12

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                       Table  1


          Recommended List of Toxic Pollutants

                Revised April 1977



 Compound Name

  1. -Kacenaphthene

  2. *acrolein

  3. *acrylonitrile

  4» *-benzene

  5. *benzidine

  6. ^carbon tetrachloride (tetrachloromethane)

     "•chlorinated benzenes (other than dichlorobenzenes)

  7»    chlorobenzene

  8.    1,2,4-trichlorobenzene

  9»    hexachlorobenzene

     "-chlorinated ethanes  (including  1,2-dichloroethane,
        1,1,1-trichloroethane, and hexachloroethane)

10.     1,2-dichloroethane

11.     1,1,1-trichloroethane

12.    .hexachloroethane

13.     1,1-di ch lo ro ethane

14.     1,1,2-trichloroethane

15.     1,1,2,2-tetrachloroethane

16.     chloroethane

    ^•chloroalkyl ethers (chloromethyl, chloroethyl,
       and mixed ethers)

17.    bis(chloromethyl)  ether
  ^-Specific compounds and chemical classes as listed
   in the consent decree

                                 13

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                   Table  1 (Contd.)



18.     bis(2-chloroethyl) ether

19.     2-chloroethyl vinyl ether (mixed)

    •^chlorinated naphthalene

20.     2-chloronaphthalene

    •"-chlorinated phenols (other than those listed elsewhere;
        includes trichlorophenols and chlorinated cresols)

21.     2,4,6-trichlorophenol

22.     para-chloro meta-cresol

23. *• chloroform (trichloromethane)

24. *2-chlorophenol

    •''•di ch lo rob en z enes

25.     1,2-dichlorobenzene

26.     1,3-dichlorobenzene

27.     1,4-dichlorobenzene

    •"dichlorobenzidine

28.     3,3'-di chlo robenzidine

    -"-dichloroethylenes (1,1-dichloroethylene and
        1,2-trans-dichloroethylene)

29.     1,1-di chlo ro ethylene

30.     1,2-trans-dichloroethylene

31. ~*2,4-dichlorophenol

    -"dichloropropane and dichloropropene

32.     1,2-dichloropropane

33.     1,2-dichloropropylene (1,2-dichloropropene)

34. "x"2,4-dimethylphenol
                               14

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                      Table  1 (Contd.)








     *-dinitrotoluene




 35.     2,4-dinitrotoluene



 36.     2,6-dinitrotoluene




 3 7. * 1,2-diphenylhydrazine



 38. -*ethylbenzene



 39. *~fluoranthene




     *-halo ethers (other than those listed elsewhere)



 40.     4-ehlorophenyl phenyl ether



 41.     4-bromophenyl phenyl ether



 42.     bis (2r-chloroisopropyl)  ether




 43.     bis(2-chloroethoxy)  methane



     -*halomethanes  (other than those listed elsewhere)




 44.      methylene  chloride  (dichloromethane)



 45.      methyl  chloride (chloromethane)



 46.      methyl  bromide  (bromomethane)




 47.      bromoform  (tribromomethane)



 48.      dichlorobromomethane




 49.      trichlorofluoromethane




 50.      dichlorodifluoromethane



 51.      chlorodibromomethane



52. -"-hexachlorobutadiene




53. "x'hexachlorocyclopentadiene



54. "x"isophorone
                                15

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                  Table' 1 (Contd.)



55. ~x~naphthalene

56. -"-nitrobenzene

    -»-nitrophenoIs (including 2,4-dinitrophenol and
        dinitrocresol)

57.     2-nitrophenol

58.     4-nitrophenol

59.     2,4-dinitrophenol

60.     4*6-dinitro-o-cresol

61  -ftnitrosamines

61.     N-nitrosodimethylamine

62.     N-nitrosodiphenylamine

63.     N-nit rosodi-n-p 2x>pylamine

64. "xpentachlorophenol

65. *phenol

    %hthalate esters

66.     bis(2-ethylhexyl) phthalate

6?.     butyl benzyl phthalate

68.     di-n-butyl phthalate

69.     di-n-octyl phthalate

70.     diethyl phthalate

71.     dimethyl phthalate

    -x-polynuclear aromatic hydrocarbons

72.     benzo(a)anthracene (l,2-benzanthracene)
                             1.6

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                   Table  1 (Contd.j








 73.    benzo (a) pyrene (3>4-benzopyrene)



 74.    3,4-benzofluoranthene



 75.    benzo(k)fluoranthene  (11,12-benzofluoranthene)



 76.    chrysene



 77.    acenaphthylene



 78.    anthracene



 79.    benzo (ghi)perylene (1,12-benzoperylene)



 80.    fluorene



 81.    phenanthrene




 82.    dibenzo  (a,h)anthracene  (1,2,5,6-dibenzanthracene)



 83.    indeno  (l,2,3-cd)pyrene  (2,3-»-pheny3pyrene)



 84.    pyrene



 85. ^"betrachloroethylene



 86. """toluene



 87. '""trichloroethylene



 88.  -'hrinyl  chloride  (chloroethylene)



    "Tjesticides and metabolites



 89.    *aldrin



 90.    ^'-dieldrin




 91.    *chlordane (technical mixture and metabolites)



    *DDT and metabolites



92.    4,4'-DDT



93.    4,4!-DDE (p,p'-DDX)



94.    4,4'-DDD (p,p'-TDE)
                             17

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                    Table  1 (Contd.)








     •frendosulfan and metabolites



 95.      a-endosulfan-Alpha




 96.      b-endosulfan-Beta




 97.      endosulfan sulfate



     -x-endrin and metabolites




 98.      endrin



 99.      endrin aldehyde




100  -x'hep tachlo r and metabo lit es




100.      heptachlor



101.      heptachlor epoxide



     -*hexachloroeyelohexane  (all isomers)




102.     a-BHC-Alpha



103.     b-BHC-Beta



104.     r-BHC  (lindane)-Gamma




105.     g-BHC-Delta



     ^polychlorinatedLbiphenyls  (PCB's)




106.     PCB-1242  (Arochlor  1242)




107.     PCB-1254  (Arochlor  1254)



108.     PCB-1221 '.(Arochlor-1221)




109.     PCB-1232  (Arochlor  1232)




110.     PCB-1248  (Arochlor-1248)




111.     PCB-1260  (Arochlor-1260)




112.     PCB-1016  (Arochlor  1016)




113. "''•toxaphene



11/i. -''-antimony (total)




115. -"^arsenic  (total)



                              18

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                    Table 1 (Contd.)



 116.  -^asbestos (fibrous)

 117.  ^beryllium (total)

 118.  -"-cadmium (total)

 119.  ^-chromium (total)

 120.  ^copper  (total)

 121.  ^cyanide (total)

 122.  *lead  (total)

 123.  -''"mercury (total)

 124.  *nickel  (total)

125.  ^selenium (total)

126.  ^silver  (total)

12?.  ^thallium (total)

128.  -K-zinc (total)

129.  *-x-2,3 , 7,8-tetrachlorodibenzo-p-dioxin
   -"-Specific compounds and chemical classes as listed
    in the consent decree

  **This compound was specifically listed in the consent decree;
    however, due to its extreme toxicity we are recommending that
    laboratories not acquire an analytical standard for this compound,
                             19

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                        Table 2
             Distribution of Plant Sampling
Toxic Pollutant Data Set

  - 12 plants - direct discharge
  - 10 plants - indirect discharge
  - 2 POTW
  - 1259 data points from 73 sample sets,  including 269 intake
    water data points, 416 raw wastewater  data points,  312 primary
    treated data points, and 262 secondary treated data points
  - 7 plants in hair pulp, chrome tan, retan-wet finish subcategory
  - 2 plants in hair save, chrome tan, retan-wet finish subcategory
  - 4 plants in hair save, non-chrome tan, retan-wet finish subcategory
  - 3 plants in retan-wet finish subcategory
  - 1 plant in through the blue subcategory
  - 2 plants in shearling subcategory
                            20

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"Leather tanning" is a general term for the numerous processing  steps
involved  in converting animal skins or hides into leather.  The three
major hide and skin types used to manufacture leather are cattlehides,
sheepskins, and pigskins.  Cattlehides  constitute  the  bulk  of  the
tanning  performed  in  the U.S., representing about 90 percent of the
total estimated weight of hides tanned.1

Three major groups  are  of  standard  processing  steps  required  to
manufacture  leather:  1) beamhouse operations which wash and soak the
hides or skins and remove the attached hair, 2)  tanyard  processes  in
which  the  tanning agent reacts with and stabilizes the proteinaceous
matter in the hides or skins,  and  3)  retanning  and  wet  finishing
processes  which accomplish further tanning by chemical agents such as
dyes, lubricants, and various finishes.

Smaller quantities of hides and skins of horses, goats, deer, elk, and
other animals are also tanned each  year  in  the  U.S.   In  general,
tanneries  purchase  hides and skins to manufacture leather for shoes,
garments, upholstery, luggage, gloves, handbags, sporting goods, and a
variety of other products.

Some plants tan and finish a single  species  of  animal  hide,  while
others tan and finish various combinations of animal hide types.  Some
tanneries  have  a  single, very specialized end-products such as lace
leather or mechanical cushions for pianos.  Other tanneries produce  a
variety  of leather types for many consumer goods and industrial uses.
The variety of final  products  produced  by  the  individual  tannery
influences  the hide types required and processing operations employed
by that facility.

Many tanneries produce finished leather from  raw,  green  salted,  or
brine cured hides; other tanneries, however, perform only a portion of
the  total  process.   Several  facilities  purchase previously tanned
hides or splits and perform  only  the  retan,  color,  fatliquor  and
finishing  processes.   A number of tanneries purchase hides and skins
which either do not require a  complete  beamhouse  process  (such  as
pigskins) or which have previously gone through the beamhouse (such as
pickled cattlehides and pickled sheepskins).

There  are  currently  188 tanneries producing leather products in the
United States.  These tanneries are primarily located in four  general
areas:   the New England states, Mid-Atlantic states, the Midwest, and
the Pacific Coast.  Most of the tanneries  are  family-owned,  closely
held   corporations,   although   a   few   are   divisions  of  large
conglomerates.  Approximately 40 percent of these  plants  have  fewer
than  50  employees and wastewater volumes typically less than 100,000
gallons per day.  About 70 percent of these plants are  more  than  50
years  old  in  terms  of  the  physical  structures  which  house the
leathermaking processes.   Although the equipment used in  some  plants
may  be  relatively modern, the typical processing techniques have not
changed for many years.  A small number of plants, usually the  larger


                                 21

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 ones,  use modern processing methods and equipment,  including reuse and
 recovery of process water and chemicals.

 Local   wastewater  pretreatment standards or limited land availability
 have caused the relocation of certain tanning  operations.    In  areas
 where   local  publicly  owned  treatment  works (POTW)  have sufficient
 capacity,   or  where  a  waste  treatment  system   can   be   readily
 implemented,  some  tanneries  have  centralized beamhouse operations.
 Centralization has generally occurred in locations  close to the source
 of raw material (hides or skins).    of  the  188 tanneries  currently
 operating  in  the  U.S.,   18  discharge directly to receiving  waters.
 POTW's provide treatment for the remainder of the industry.

 Beginning in the mid-19601s and continuing until 1974,   the domestic
 leather tanning and finishing industry experienced  a steady decline in
 the number of plants,  production  volume,  and profits.   This trend, as
 indicated in Table 3,  was  attributed to:   1)   greater  foreign   demand
 for cattlehide,  which caused an increase  in raw material cost,  and 2)
 competition from foreign countries in the   finished  leather products
 market.

 The industry's economic situation has continued to decline,  despite  a
 short-term  improvement  from  1974  to  1976;   nevertheless,   it   may
 stabilize   in  the  future  as the  demand for leather products balances
 relative to leather substitutes.   Prospects for  new plants  vary among
 segments   of  the  industry;   entry  of new plants appears  likely  for
 tanneries  which can take advantage of strong demand and   economies  of
 scale.

 STANDARD MANUFACTURING  PROCESSES

 Animal  skin  is   composed   of   outer and  inner  (epidermal and  dermal)
 layers and  it  is   the   inner   (dermal)   layer  which constitutes   the
 leather-making   portion  of   the   skins  and hides.    This dermal layer
 consists mainly of the  protein collagen.   Tanning is  essentially   the
 reaction   of  collagen   fibers  with   tannin,  chromium, alum, or other
 tanning agents  which help stabilize,  or  preserve, the skin and make it
 useful.

 Water is essential to leathermaking   and   is   used   in  virtually   all
 manufacturing   processes.   Various   chemical  preservatives, biocides,
 coloring pigments, and solvents also  are integral to producing leather
 from animal hides  or  skins.   The  standard  manufacturing  processes
 characteristic  of  the  industry are shown  schematically in Figure 1.
 Each of the  four major process groups  (beamhouse, tan, retan, and  wet
 finish) consists of specific subprocesses.

 For  the purpose of this study, EPA defines a manufacturing process as
a  single  step  in  the  complete   manufacturing   operation   where
alternative  steps  may  result in different waste characteristics.  A
process can consist of one  or  a  series  of  subprocesses.   In  any


                                 22

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Figure  1     GENERAL PROCESS  FLOWSHEET  FOR  LEATHER TANNING AND FINISHING INDUSTRY
                           24

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defined  process,  subprocesses  remain  the  same.   This  concept of
manufacturing steps seems to best allow for the variation of processes
used by different plants.

The discussion and description of tannery processes which  follow  are
based  on  the  three  major hide and skin types produced in the U.S.:
cattlehides, sheepskins, and pigskins.  The processes and subprocesses
discussed represent those most typical of the industry.

Cattlehide Tannery Processes

Much of the following process  description  of  a  typical  cattlehide
tannery  was  developed  in  detail from the book. Leather Facts2, and
from  industry  questionnaires  and  plant  visit  reports.   Detailed
descriptions  of  typical  cattlehide  tannery  process and subprocess
operations follow.

Receiving and Storage.  Nearly all cattlehides received  at  tanneries
are  either  green  salted  or brine-cured hides, with the brine-cured
hides predominant.  In the few isolated cases where  transit  time  is
short, fresh green hides  (without prior curing)  are sent directly from
a meat packer to a tannery for immediate processing.

After  being  trimmed  and  graded,  green  hides  are  cured  at  the
packinghouse by spreading the hides, flesh side up, and covering  them
with  salt.   Another  layer of hides is placed over the salted hides,
again flesh side Up, and covered with salt.   This  process  continues
until  the  pack of hides is about 5 to 6 feet high.  A heavy layer of
salt is placed on the top layer of hides.  The natural fluids from the
hides dissolve a portion of the salt to form  a  brine,  allowing  the
salt  to be absorbed.  Through diffusion and osmosis, the salt reduces
the moisture content in the hide.  A pack of hides is typically  cured
for  10  to  30  days.   After  the green salted hides have been cured
adequately the pack is reopened and the excess salt is shaken off each
hide.  The cured hides are  then  folded  individually,  repacked  and
shipped  in  packs,  either  to  other  tanneries or to warehouses for
storage.  The size of the pack depends on a number of variables,  such
as  size  of  the  packing  plant,  size  of  shipments, and method of
shipment.

Brine-cured hides are prepared either at the packing  plant  or  at  a
separate  hide  processing  facility.   Fresh  hides are agitated in a
saturated brine solution for two or three days,   until  the  salt  has
replaced  a  desired amount of moisture within the hide.  This process
also cleanses the hides of manure and other foreign matter.  The hides
are then removed, drained, and bundled in a  manner  similar  to  that
used  for  green  salted  hides.   Fleshing  may occur before or after
brining.  "Safety salt" is  usually  sprinkled  on  each  hide  before
shipment.   Because  the  brining  process  takes less time than salt-
curing, it is preferred by  packers  and  hide  curing  establishments
which  do  not  want  to hold a large inventory of hides.  The brining


                                 25

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process also produces cleaner hides, which are more attractive to  the
tanners.    Increased   use  of  brine-cured  hides  in  recent  years
demonstrates these preferences by both packer and tanner.

Normally the tannery receives the cured hides in a large,  cool,  well
ventilated  area  designed  to  preserve the moisture content at which
they were received; packs are usually stored in the form in which they
are received. From storage, they are taken  to  the  beamhouse,  where
they are prepared for tanning.              '

Beamhouse  Processes.   There are four typical processing steps in the
beamhouse:  1)  side and trim; 2)  soak and wash; 3)   fleshing;  and  4)
unhairing.                                                           '

     Side and Trim.

     The  typical  first  step in preparing hides for processing is to
     trim off the heads, long shanks, and other perimeter areas  which
     do  not  produce good leather.   The hides are then cut lengthwise
     along the  backbone, head to  tail,  to make  two  sides.   In  some
     instances,  hides are halved or sided after unhairing or tanning.
     Trimmings  are often collected for  shipment to glue  factories  or
     other by-product manufacturers.

     Soak and Wash.

     The  hides soak  in vats  (with or without  paddles),  drums,  or hide
     processors (concrete mixers  with special  linings)   for  8   to  20
     hours  to   restore moisture  which  the hides have  lost  as a result
     of the curing process.   They gradually   absorb   water,   becoming
     softer  and  cleaner.    Washing then removes dirt,  salt,  blood!
     manure,  and non-fibrous  proteins.   There  may be some  variation in
     the quantity of  such waste materials  according  to  the   time  of
     year  and   the source of hides.  According  to the type of  leather
     produced,  additional washes   (rinses)  may   also  follow  several
     subprocesses including  unhairing,  bating,  tanning, and  coloring.
     A  rinse  operation  may also   precede   the  coloring  of  hides   or
     s Jti ns.

     Fleshing.

     Fleshing   is  a  mechanical operation which removes excess flesh,
     fat and muscle from  the  interior  of  the   skins.   The  fleshinq
     machine  carries  the  hide  through  rollers and across rotating
     spiral blades which  remove the  flesh  from the hide.    cold  water
     is  necessary  to  keep  the  fat  congealed,  but  the  fat does
    represent  an additional waste load.

    Many hides are fleshed at packing  plants  or  at  separate  hide
    processing  facilities,  particularly  brined  hides.  Removal of
    flesh prior to liming is referred to as green  fleshing;   removal


                                26

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after  liming  is  referred  to  as  lime fleshing.  In any case,
fleshings  (i.e., the removed particles)   are  normally  recovered
and sold to plants for rendering or conversion to glue.  Properly
handled,  this  operation contributes very little liquid or solid
waste.  On-site rendering of fleshings,  however, does  contribute
an  additional  waste  stream (stick liquor), which is relatively
low-volume but extremely concentrated.

Unhairing.

The removal of hair usually  employs  calcium  hydroxide,  sodium
sulfhydrate,  and  sodium  sulfide  as the dehairing (depilatory)
chemicals.  These chemicals:  1) destroy the hair or  attack  the
hair  roots,  2)  loosen  the  epidermis,  and  3)  remove certain
soluble skin proteins.

Fleshed hides are placed in paddle vats  containing water and  the
depilatory  chemicals.  The concentration of chemicals, the water
temperature, and the amount of agitation directly affect the rate
at which unhairing  proceeds.   In  a  pulp  or  brine  unhairing
operation,  concentrated chemicals and high temperatures dissolve
the entire hair within a few hours.  If  the hair is saved for its
commercial value, a longer procedure using weaker  solutions  and
lower  temperatures  is  employed.  This process attacks the hair
roots only.  The loosened hair can  then  be  collected,  washed,
dried, and either sold where markets exist, or landfilled.

Where chemical treatment alone does not  remove all of the hair or
hair roots, the process can be completed on an unhairing machine.
This  is  very similar to a fleshing machine, except the cylinder
blades are blunt and rub the hide rather than cut it.

The lime and sulfide chemicals  used  in  the  unhairing  process
produce a concentrated alkaline solution, causing the hide fibers
to  absorb  large amounts of moisture.  This makes the hide swell
to about twice its normal thickness, a phenomenon called alkaline
swelling.  Some tanners relime the hides  prior  to  deliming  to
ensure  complete hair removal and uniformity of alkaline swelling
within the  hide  substance  prior  to  deliming.   Use  of  this
subprocess  depends  upon the nature of  the hides being processed
and the types of final products desired.

A. few tanneries now use a  hybrid  hair   removal  process,  which
compromises  the  two extremes of pulping (dissolving)  and saving
the hair.  The semi-pulp unhairing process is a natural outgrowth
of the traditional hair  save  operation.   In  many  cases,  by-
product hair markets no longer exist or  the cost of hair washing,
baling,  and  selling  exceeds  income  for  the  hair.  In these
instances, tanners have simply made  marginal  increases  in  the
concentration  of  unhairing  chemicals,  and retained the use of
unhairing machines.  This falls short of complete changeover to a


                            27

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 hair pulp  beamhouse,   but  retains  the  hair  save  option  and
 maintains   a  process  with  which  the  operator  is  basically
 familiar.  In these cases, raw waste loads tend to be  about  the
 same as for complete pulping of hair.

 Tanyard  Processes.   Hides are brought from the beamhouse  to the
 tanyard  for  further   preparation  and  then  tanning.   Tanyard
 processes are described below.

 Bating.

 Bating  is  a  two-step process consisting of deliming and  enzyme
 addition.  Residual alkaline  chemicals  used  in  the  unhairing
 process  are  present  in fairly large  amounts and must be removed
 prior to tanning.   In  deliming,   salts  of  ammonium  sulfate  or
 ammonium   chloride   convert  the  residual  lime  into soluble
 compounds which later  can be washed free of the system.  As   this
 step  progresses,   the  excessive  alkaline  swelling  begins  to
 disappear,  and the  skins return to their normal  thickness.    The
 deliming  chemicals also properly condition the pH for  receiving
 the  bate.

 Bates are enzymes similar to those found in the digestive systems
 of animals.   These  natural catalysts facilitate separation of the
 collagen protein fibers  through hydrolytic destruction of peptide
 bonds which cross-link the chains  of amino  acids.    Bating   also
 attacks    and  destroys   most    of   the   remaining   undesirable
 constituents of the skin,   such  as   hair  roots   and  pigments.
 Removal  of  these materials  softens  the  grain surface  and gives  it
 a  cleaner   appearance.    Modern  bates   are actually mixtures  of
 chemical   deliming  agents   and   selected    enzymes,   permitting
 simultaneous operation of  both  phases of  this subprocess.

 As in unhairing, the amount  of bating chemicals, the  temperature,
 and  the  reaction time  are  critical.  Commercial  processes vary  in
 length   from a  few  hours to  overnight, depending on the  nature  of
 the  skins being handled.  At the conclusion  of bating, the  hides
 are   thoroughly  washed  to remove all of the substances  that  have
 been  loosened or dissolved.

 Pickling.

 Pickling prepares the hides  to  accept  the  tanning  agents  by
 providing  an  acid  environment  -  an  essential step  in chrome
tanning.  Chrome tanning agents  have  minimum  solubility  under
alkaline   conditions;    the   acid   environment  thus  prevents
precipitation of chromium salts.   Pickling  most  commonly  uses
sulfuric  acid,  with  common  salt  or  brine first added to the
system.  If acid alone  were  to  be  added,  excessive  swelling
 (similar  to  alkaline  swelling) would develop, either producing
                            28

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inferior leather  or  converting  the  hide  into  an  untannable
gelatinous mass.

Controlled  acid swelling helps separate collagen protein fibers,
which facilitates further complexing of the hide by  the  tanning
agent   (i.e.,   trivalent   chrome)  and,  thus,  more  complete
stabilization.  The salt and acid solution completely  penetrates
the hide in a few hours.

The pickling operation is a preserving technique in its own right
and skins can remain in this state for extended periods of time.

Tanning.

Tanning agents convert the raw collagen fibers of the hide into a
stable  product which is no longer susceptible to putrefaction or
rotting.  They also significantly improve many of the  mechanical
properties  of  the raw material including dimensional stability,
resistance to abrasion,  chemical  resistance,  heat  resistance,
flexibility, and the ability to endure repeated cycles of wetting
and drying.

The  predominant  tanning  agents  used in the U.S. are trivalent
chromium and vegetable tannins extracted primarily from  specific
tree  barks.   Other  principal  tanning  agents include alum and
syntans.

Vegetable tanning is an older process  performed  in  a  solution
containing  plant  extracts.   This  method  is applicable to the
production of heavy leathers, such as  sole  leather,  mechanical
leather,  and  saddle  leather.   Vegetable tanning usually takes
place in vats because of  the  longer  reaction  times  involved.
Recycling  of  vegetable tan solutions is becoming more common in
the industry; unrecycled solutions may be used for  retanning  or
may be evaporated for recovery and reuse.

Tanners  generally  prefer  chromium  tanning because it produces
leather that best combines most  of  the  chemical  and  physical
properties  preferred for the majority of leather uses.  Chromium
tanning also takes place in a shorter period  of  time  (4  to  6
hours) than vegetable tanning,

The chemical state of the tanning agent, as well as the condition
of  the  hides and interior of the drum, is important with regard
to the thorough penetration of the chromium into the  hide.   The
addition  of  sodium  bicarbonate and formic acid  (masking agent)
increase the affinity of the separated  collagen  protein  fibers
for the chrome.

The older and more traditional method of chrome tanning, known as
the  "two-bath"  method, entailed the use of hexavalent chromium,


                            29

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 which can be very toxic.  The hexavalent  chrome  penetrates  the
 hide during the first bath; the second bath introduces a reducing
 agent   (such  as  thiosulfate) which "blues" the hides by in  situ
 chemical reduction of chromium  to  the  trivalent  state."  ThiS
 process complexes the proteins.                     *wte.    mis

 Very few tanners have continued the use of the "two bath" method
 The  dangers  of  handling  hexavalent  chromium  and the reduced
 processing  time  and  chemical  cost  incurred  in  the  use  of
 Some tanners  still  purchase  hexavalent  chromium  (bichromate

 d^^!te)   a?d  redU°e  it:  on'site to the trivalent state with
 dextrose or molasses and acid.  This approach  results  primarily
 from  the  cost  differentials  between  hexavalent and bivalent
 chromium in certain geographical  areas.   The  danger  of  ?oxic
 hexavalent  chromium  spills  exists even where adequate operator
      01 1  exerclsed'  Although certain tanneries  have  minimized
                                                      of  improved*
 Wringing.
 In  preparation of the  blue hide for splitting,  excess moisture is
 removed from the hide  by wringing.   The hides are fed  through  a

 wringer e
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Retan. Color, Fatliquor, and Finishing Processes.   To  give  the
tanned  hide  special  or  desired characteristics, a tannery may
employ further processing steps, as described below.

Retanning.

Most tanners have neither the equipment nor the low-cost labor to
support multiple  beamhouse  and  tanyard  formulae  for  various
finished leather products.  Most hides are therefore subjected to
identical   processing  through  the  blue  state.   The  primary
function  of  retanning  is  to  impart  characteristics  to  the
finished  leather  which  it  lacks following the initial tanning
step.  The more common retanning agents are  chromium,  vegetable
extracts,  and  syntans.    Other agents such as as zirconium and
gluteraldehyde, however, are used for very  small  quantities  of
leather.   Retanning  usually takes place in a drum during a one-
or two-hour perod.

Vegetable extracts help to minimize any variation that may  exist
between  different  parts of the chrome tanned hide.  Syntans are
man-made chemicals which are used extensively in the  manufacture
of  the  softer  side  leathers.   Because  of  their  pronounced
bleaching effect on the bluish-green  color  of  chrome  tannage,
syntans are used in making white or pastel shades of leather.

Bleaching.

After  tanning, "hides can be bleached in vats or drums containing
sodium bicarbonate and sulfuric acid.  This is commonly practiced
in the sole leather industry.

Coloring.

Dyes are added  to  the  same  drums  used  for  retanning.   Two
important  factors in coloring are:  1) skin variability, such as
varying pigmentation, and 2) color penetration, or the  depth  to
which the coloring material passes into the leather.

Typical  dyestuffs  are  aniline based, and combine with the skin
fibers to form an insoluble  compound.   Shades  and  degrees  of
penetration  can  be  varied by controlling pH, which affects the
affinity of the dye for the leather fibers.

Fatliquoring.

The fatliquoring process lubricates the fibers so that  they  can
slide  over  one  another.   Oils and related fatty substances in
fatliquors replace the natural oils lost  in  the  beamhouse  and
tanyard  processes.   Chemical emulsifiers added to the fatliquor
ingredients  permit  their  dispersion  in  water.   Fatliquoring
requires  approximately  one  hour to complete.  Use of differing


                            31

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 amounts of oil permits the tannery to vary the  firmness  of  the
 final product,

 Fatliquors  typically  and  predominantly are either of animal or
 vegetable origin, or are synthetics made from  modified  mineral-
 based  oils.   Straight-chain  aliphatic mineral oils are used in
 very small quantities for specialty products such  as  mechanical
 and heavy shoe leathers.

 Finishing.
 The finishing process includes all of the operations performed on
 the   hide  following  the  fatliquoring  operation.   Generally,
 trimmings and dust collected during these  processing  steps  are
 disposed  of  as  solid  wastes; however, dust may also enter the
 plant's liquid waste stream.  There are  a  number  of  finishing
 steps*

 Setting  out smooths and stretches the skin while compressing and
 squeezing out excess moisture.

 Drying  uses four methods:

 1)  hanging, in which hides are  draped over a horizontal shaft and
 passed  through a large drying oven;

 2)  toggling,  in which the  skins dry  in a  stretched  position  on
 frames  which  are slid into channels  of a drying oven;

 3)   pasting,   in which the skins are pasted onto plates which are
 subsequently  placed  in a drying oven;  and

 4)  vacuum  drying,  in which hides are smoothed   out   on   a   heated
 steel   plate   and covered  by  a perforated belt or cloth-covered
 steel plate.   A vacuum then extracts water  from the leather.

 Unlike  the  first three drying processes,  which   require 4  to  7
 hours   per  skin,  vacuum drying can  be  accomplished in  only three
 ?«h-^?% minutes.    Shrinkage   of   the   leather,   however,   has
 inhibited widespread  adoption of  vacuum drying  by the industry.

 Conditioning   involves   spraying  a  mist on the hides, which are
 then piled  on  a  table, wrapped  in a  watertight   cover,  and  kept
 overnight   to  permit  uniform  moisture  distribution within the
 learner.

 stakincT stretches and flexes the leather on  automatic  equipment
 to make it  soft and pliable.

Dry milling tumbles the hides in a large drum.
                            32

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     Buffing  smoothes  or  "corrects"  irregularities  in  the  grain
     surface by mechanical abrasion.

     Finishing may be applied to the leather, depending on the end use
     and type of hide.  Various finishes, both water-base and solvent-
     base, provide abrasion and stain resistance  and  enhance  color.
     Solvent-based  coatings are employed only for special high-luster
     finishes.  Use of these coatings has been curtailed  largely  due
     to handling difficulties and their inherent fire hazard.

     Plating  is  the  final  processing  step,  which  influences the
     appearance and feel of leather.  It smoothes the surface  of  the
     coating  materials,  while bonding them firmly to the grain.  The
     finishing and plating operations occur in conjunction  with  each
     other  over  a  period  of  four to five days.  Hides may also be
     embossed  (stamped with a particular pattern).

     After finishing, the surface area of the hide is determined,  and
     the  product  is  graded  for  temper,  uniformity  of  color and
     thickness, and the extent of any surface defects.

Sheepskin Tannery Processes

The manufacture of leather from sheepskin  is  similar  to  cattlehide
tanning,  except  that  the beamhouse process typically is absent.  In
addition,  sheepskins  require  degreasing  prior  to  tanning.    The
processes  and subprocesses which differentiate sheepskin tanning from
cattlehide operations are described below.

Tanyard  Processes.   U.S.  tanneries  receive  sheepskins  from  both
domestic  and  foreign  sources.  Imported skins generally arrive in a
pickled condition, preserved for shipment and storage by immersion  in
a  solution  of  brine  and acid.  Excess solution is drained prior to
handling the skins, which are normally tied in bundles of  one  dozen.
The wool is removed from the skins at the packinghouse or wool-pullery
before  the skins are processed to the pickled condition.  Skins which
arrive with the wool intact are referred to as shearlings.   Shearling
skins are cured in a salt brine only.

The  hides  normally  are  stored  in  the  bundles as received.  Some
tanneries indicated that  pickled  skins  held  for  extended  periods
should   be   kept  below  30  degrees  C  (86  degrees  F)   to  avoid
deterioration.   Biocides,  such  as  chlorinated  phenolics,   retard
bacterial action and lengthen storage time.

From  storage,  skins  are  taken  from  the  bundles,  inspected, and
fleshed.  Tanneries which  receive  fleshed  sheepskins  will  usually
reflesh  them  after  tanning; typically, however, sheepskin hides are
fleshed after a wash and soak operation.  Fleshing is done on the same
type of machine employed for  processing  cattlehides.   The  skin  is
carried through rollers and across rotating spiral blades which remove


                                 33

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 the  attached  flesh.   Fleshings and trimmings are collected as solid
 waste.
 The fleshed skins are placed in drums, soaked, and washed.   An  added
 solvent  or  detergent  then  removes  grease.  Grease by-products are
 recovered from those skins which have  had  the  wool  removed.   when
 solvent degreasing is employed, the solvent is recovered for reuse.

 Shearlings require substantially more water in the soaking and washing
 operations.    Grease  recovery  is  not  a  conventional  practice for
 shearling tanneries; these hides may be pickled in a  process  similar
 to that described for cattlehides.

 Sheepskins  may  be  either  chrome  or vegetable tanned, although the
 majority are tanned with chrome.  Pickled skins require no  liminq  or
 bating.   Degreased  skins  are  placed  in  drums with salt water and
 mixtures of  basic chromium sulfate for chrome tanning or solutions  of
 the natural  tannins for vegetable tanning.

 In   some cases,  a  refleshing  operation  follows  the  tanning  of
 sheepskins.

 Retan,   Colorr   Fatliguor,   and  Finishing   Processes.     The   retan
 processing  step  proceeds   in  a  manner  similar  to  the cattlehide
 retanning operation.

 Skins to be  colored are immersed in a dye solution contained in drums.
 Generally, synthetic dyes  are  used,  and  sometimes  shearlings  are
 bleached prior  to coloring.                               eaia.j.«gs>  are

 Fatliquoring takes  place   in  the same  drum used for coloring and is
 designed to  replace the natural oils of the skin  lost in  the  tanninq
 process.   The process is similar to cattlehide fatliquoring.

 A   number of operations  follow the sheepskin coloring and fatliquoring
 aSP(L%i™1Udi!S  dryina<  skiving,  staking,  carding,  clipping,  sanding,
 and buffing.  These are  essentially dry operations  which  generate some
 m™1^™8??8 
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frozen  skins  may  be  delivered  in  paper bags.  Most tanneries use
refrigerated storage for skins held before tanning.

Most pigskin tanneries use solvent degreasing.  The skins  are  placed
in  drums,  then soaked and washed in warm water to bring them up to a
suitable temperature for degreasing.  Solvent is  then  added  to  the
drums  and  the  skins  are tumbled to facilitate grease removal.  The
solution of solvent, grease, and water is pumped  from  the  drums  to
large  tanks, where some separation occurs.  This allows decanting and
discharge of the water fraction to the plant sewer.   From  the  tanks
the  solvent  and  grease mixture is sent to a stripping column, which
recovers the solvent for reuse.  Grease is then  recovered  as  a  by-
product .

Some  tanneries  have  adopted an alternate degreasing method in which
the skins are tumbled in hot  water  and  detergent.   Following  this
operation,  the degreasing solution is diverted to holding tanks where
grease by-products are recovered by decanting or skimming from the top
of the tanks.

The skins are then placed in tanning drums  with  a  lime  slurry  and
sharpeners.   This  step is to remove the embedded portion of the hair
from the skins.

The bating operation, similar to  that  used  in  cattlehide  tanning,
takes place in the same drums used for liming.

Also, as in the cattlehide tanning, the pickling step places the skins
in  an  acid  bath  to  prevent  precipitation  of  chromium salts and
facilitate tanning.  The required constituents are added to  the  same
drums used for bating and liming.

Pigskins  may  be either chrome tanned or vegetable tanned.  The major
pigskin tanner in this country,  however,  uses  strictly  the  chrome
tanning  process.   Chrome tanning is conducted in the same drums used
for liming, bating,  and  pickling  by  immersion  in  a  solution  of
chromium  sulfate.   The current practice is to fully tan the skins in
this operation, eliminating any need for a retan operation to  produce
a final product.

After  being  tanned,  the skins are tumble dried, split and shaved to
obtain the desired thickness.  Since the split portion of the  pigskin
has  no  commercial value as leather, it is baled with other scrap and
sold as a fertilizer component.  The  grain  sides  are  subjected  to
subsequent processing operations.

Color, Fatliguor, and Finishing Processes.  Typically, tanned pigskins
are  colored  by  immersion  in a solution containing a synthetic dye.
The process considerations are similar to those involved in cattlehide
tanning.
                                 35

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The  purpose  and  methodology  associated   with   the   fatliquoring
processing  step  for  pigskins parallel those outlined for cattlehide
and sheepskin fatliquoring.

A. number of operations typically follow the color and fatliquor steps.
These are principally dry subprocesses similar to those described  for
cattlehide tanning.
                                36

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                              SECTION IV

                      INDUSTRY SUBCATEGORIZATION

SUMMARY

In  developing effluent limitations guidelines, new source performance
standards and pretreatment standards for the leather tanning industry,
it was necessary to segment the industry into  relatively  homogeneous
groups  or  subcategories.  EPA found that the most significant factor
for  subcategorizing  regulated  industries  is  the  product,   which
accounts  for such factors as the types of raw materials processed and
the manufacturing processes employed.

The raw material of the leather tanning industry is the hide  or  skin
type  subjected to the processing operations.  Manufacturing processes
then relate to the type of raw material received by the facility.  For
example, some tanneries process previously tanned hides or skins, thus
eliminating the need  for  beamhouse  operations.   Other  significant
process  considerations  include  the tanning process utilized and the
presence of finishing operations, including retanning.

In subcategorizing industries, EPA also examines plant size,  age  and
location   (including   climate),   wastewater   characteristics   and
treatability, engineering aspects  of  various  control  technologies,
costs,  economic  impacts,  and  other  factors.  In most cases, these
factors do not justify additional subcategorization, but  substantiate
subcategorization based on commodity (raw material and process).

The   factors  considered  for  subcategorizing  the  leather  tanning
industry are summarized as follows:

1. raw material

 a. cattlehide,

 b. split,

 c. pickled sheepskin,

 d. shearling,

 e. pigskin;

2. manufacturing processes

 a. beamhouse operations,

 b. tanning process (chrome, vegetable, alum),

 c. finishing operations  (including retanning);


                                 37

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 3.  plant  size

 4.  plant  age

 5.  plant  location  and  inherent  climate

 6.  wastewater  characteristics and treatability

 7.  engineering aspects of the application of various
     treatment technologies

 8.  non-water quality impacts

 9.  costs

 10. economic impact.

 EPA has determined that raw material and manufacturing process are the
 most significant factors in subcategorizing the leather tanning  point
 source  category.  Seven subcategories have been developed  (originally
 six).  Four of the subcategories primarily  cover  the  cattlehide  to
 leather   segment  of   the industry; two subcategories cover operations
 which have no  beamhouse and the seventh subcategory  covers  shearling
 tanning  (sheepskin with hair intact).

 The seven subcategories are defined as follows:

 1-  Hair  Pulp/Chrome Tan/Retan-Wet Finish - facilities which primarily
 process raw or cured cattle or cattle-like hides into finished leather
 by  chemically  dissolving the hair (hair pulp);  tanning  with  chrome;
 and retanning  and wet  finishing.

 2-  Hair  Save/Chrome Tan/Retan-Wet Finish - facilities which primarily
 process raw or cured cattle or cattle-like hides into finished leather
 by  chemically  loosening and mechanically removing  the  hair;  tanning
 with chrome; and retanning and wet finishing.

 3.   Hair Save/Non-Chrome Tan/Retan-Wet Finish   -   facilities  which
 process raw or cured cattle or cattle-like hides into finished leather
 by  chemically  loosening and mechanically removing  the  hair;  tanning
 with  primarily  vegetable  tannins,  alum,   syntans,  oils,  or other
 chemicals; and retanning and wet finishing.

 U. Retan-Wet Finish - facilities which process previously unhaired and
 tanned hides or splits into finished leather through retanning and wet
 finishing processes including coloring,  fatliquoring,  and  mechanical
 conditioning.

 5-  No Beamhouse  -  facilities   which process previously unhaired and
pickled cattlehides,  sheepskins  or pigskins  into finished  leather  by


                                 38

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tanning  with  chrome  or  other agents, followed by retanning and wet
finishing.

6. Through-the-Blue - facilities which process raw or cured cattle  or
cattle-like  hides  into  the  blue  tanned  state only, by chemically
dissolving or loosening the hair and  tanning  with  chrome,  with  no
retanning or wet finishing.

7.  Shearling  - facilities which process raw or cured sheep or sheep-
like skins into finished leather by retaining the hair  on  the  skin;
tanning with chrome or other agents; and retanning and wet finishing.

RATIONALE FOR SUBCATEGORIZATION

Raw Material

The hide or skin type received by a tannery imposes specific processes
on the manufacture of leather products.  This relationship between raw
material  and manufacturing process establishes hide or skin type as a
basis for industry subcategorization.

The original development document grouped tanneries into six segments.
Table 4 compares the original listing of six industry segments to  the
seven  subcategories  which are defined in this document.  The updated
industry subcategorization segregates shearling tanning from the other
no beamhouse operations because of the nature  of  the  raw  material.
Preparation  of  the  sheepskins  for  tanning  with  the  wool intact
requires significantly more  washing  than  is  required  for  pickled
skins.   This  results  in  higher flows and waste loads for shearling
operations, which therefore warrant a distinct subcategory.

The presence and length of hair on the hides  or  skins  being  tanned
determines  the  manufacturing  processes required and helps determine
the character of the plant waste stream.  Removal of  hair  (beamhouse
subprocesses) increases tannery waste loads in terms of most pollutant
parameters  such  as  BOD5,  COD, TSS, TKN, etc.  Hair length (as with
shearlings) also affects waste generation, especially water use.   For
the  purpose  of subcategorizing tanneries three basic hide/skin types
are important:

1. Cattlehide or cattie-like hide - short hair, relatively heavy hides
or skins  (includes splits).  Deerskin,  horsehide,  cow  bellies,  and
other similar hides are included in this group.

2.  Sheep  or  sheep-like skins - long hair and relatively light skins
(includes shearlings).  Goatskin and other similar hides are  included
in this group.

3.  Pig  or  pig-like  skins  - short hair or hairless, and relatively
light skins.  This group includes only skins which have little  or  no
hair.
                                 39

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Table   4    Subcategory Comparison by Principal Processes
Present Document Subcategory
1.
2.
3.
4.
5.
6.
7.
Hair Pulp, Chrome Tan,
Retan-Wet Finish
Hair Save, Chrome Tan,
Retan-Wet Finish
Hair Save, Non-Chrome Tan,
Retan-Wet Finish
Retan-Wet Finish
No Beamhouse
Through-the-Blue
Shearlings
EPA Development Document
March 1974 Subcategory
1
2
3
4
5
6
5

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Manufacturing Processes

Beamhouse Operations.  The existence of or type of beamhouse operation
in  a  leather  tannery  is a significant factor in subcategorization.
Unhairing operations typically contribute high  raw  waste  flows  and
loadings  at  tanneries  with  a  beamhouse.   The  specific unhairing
process  (i.e., hair pulp or hair save)  also  affect  beamhouse  waste
characteristics  and  loadings,  since  hair  dissolving  (or pulping)
contributes lower flows but more pollutant discharges.   In  addition,
preliminary treatment of segregated beamhouse wastewaters is necessary
for  plants  which  include  these  subprocesses.   EPA  has therefore
subcategorized  the  tanning  industry  to   reflect   the   following
variations of beamhouse operations:

1.  Pulp  hair  -  hair is chemically dissolved from the hide/skin and
enters the liquid waste stream.

2. Save hair  (and  wool  pullery)  -  hair  (or  wool)  is  chemically
softened  and  mechanically removed.  The major portion of the hair is
removed as a solid, thus preventing it from entering the liquid  waste
stream.  Residual roots and fragments may be lost to the waste stream.

3.  No  beamhouse  - hides or skins are received with the hair already
removed; a beamhouse operation is therefore not needed and the tannery
does not generate the beamhouse-type waste stream.  Raw materials that
require little or no  hair  removal,  such  as  pickled  sheepskin  or
cattlehides, shearlings, and pigskin are included in this group.

Tanning  Process.  This process is primarily a function of the tanning
agent  used.   The  industry  in  the  U.S.  employs  various  agents,
including  chrome,  vegetable  tannins,  alum and syntans.  Non-chrome
tanning methods may generate highly colored waste streams,  but  flows
and  waste  loads  are  slightly  less  than those observed for chrome
tanning operations.  Facilities which only retan and finish previously
tanned hides should be considered  separately  because  the  resulting
waste streams contain reduced mass of residual tanning compounds, such
as chromium.

Since  tanning processes influence the flow, waste characteristics and
pollutant  loadings  for  each  tannery's   waste   stream,    industry
subcategorization reflects the tanning process as follows:

1. Chrome tanning - at least 20 percent of the total tonnage is tanned
with this agent.  A significant number of plants use only this tanning
method  and for most facilities, chrome represents the primary tanning
agent.

2. Non-chrome tanning - less than 20 percent of the total hide tonnage
is chrome tanned.   The  primary  non-chrome  tanning  agents  are  of
vegetable  tannins   (primarily  extracts  from  specific types of tree

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bark) with significantly  less  utilization  of  alum,  and  synthetic
agents.

3.  Previously  tanned  -  no tanning is carried out because the plant
receives  fully  tanned  hides  which  require  only   retanning   and
finishing.

Retanning  and  Wet  Finishing Operations.  The presence or absence of
retanning  and  wet  finishing   (coloring,  fatliquoring,   etc.)   is
significant   for   industry   subcategorization.    These   processes
contribute significantly to the total waste stream of  tanneries  with
or  without  a  beamhouse, most importantly to total water use.  At No
Beamhouse tanneries, retanning and wet  finishing  operations  have  a
considerable impact on total waste flows and pollutant loadings.

Some  tanneries  restrict processing to retanning and wet finishing of
hides and skins received in the tanned state.  These facilities  incur
water  usage  and  raw waste loadings which are considerably less than
those observed for more complex  tanneries  conducting  beamhouse  and
tanning operations.

Plants  which  start  with  "crust"  leather (wet finishing previously
completed) are not considered tanneries and were  excluded  from  this
study.

Plant Size.  EPA defines the size of a tannery as the number or weight
of  hides  and skins processed in a day.  Most subcategories contain a
wide range of plant sizes or production levels.  The  ratio  of  flows
and  raw  pollutant  loadings to units of production remains constant,
however, essentially independent of plant size for  each  subcategory.
The Agency found no other factors which coincide with plant size to be
relevant for subcategorizing the industry.

Plant Age.  No consistent difference in plant operations or wastewater
generation  was  associated with tannery age.  The physical structures
for most plants  are  quite  old,  but  even  the  newer  plants  have
processing  equipment  similar  or  identical to much of the equipment
found in the older tanneries.  In fact, many older plants have certain
pieces of processing equipment which are quite modern,  such  as  hide
processors,   "Turbotan"   processors,   and   "Idronova"   separation
equipment.

Plant Location  and  Climate.   There  was  apparently  no  detectable
relationship between plant location and raw waste loadings; neither do
tannery  location and raw material source necessarily coincide.  Hides
and skins are usually purchased  for  specific  product  applications.
With  rare  exceptions,  the  geographical location of a plant and its
source of raw material are basically independent.

Climate, directly related to  geographical  location,  also  does  not
influence   the  processing  activities  of  tanneries  in  the  seven


                                 42

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 subcategories.  For a given raw material, the  selection of  processing
 steps  remains  the  same.   Water  usage  and raw waste loads are not
 affected by climate, since they are primarily  a  function  of  hide  or
 skin  type  and  manufacturing  processes  employed.  Furthermore, the
 Agency  found  that  climate  does  not  affect  the  treatability  of
 wastewaters  and  achievable  final  effluent  concentrations.  Climate
 does, however, affect the specifics of  design,  equipment  selection,
 and  especially operational requirements of treatment systems.  Plants
 in northern cold climate areas  can  be  expected  to  incur  somewhat
 higher  costs  to  ensure  consistent  operation during winter months.
 Where appropriate, these factors have been considered  in  development
 treatment  system  component  costs  with  no  difference  in economic
 impacts identified.   No  differences  were  identified  in  non-water
 quality   impacts   attributable   to   climate.   Therefore,  further
 subcategorization of the leather tanning industry based on climate  is
 not warranted.

 Wastewater   Characteristics   and   Treatabilitv.    To   assess  the
 subcategorization of the leather tanning industry regarding wastewater
 characteristics and treatability, the Agency reviewed information from
 various  sources.   Substantial  data   for    conventional   pollutant
 parameters  and  for  sulfide  and  chromium   were available; however,
 information for other toxic pollutants was limited essentially to that
 generated during the course of this study.  The data for  flow, 'BODS,
 suspended  solids, sulfide, and chromium supports the updated industry
 subcategorization  set  forth  above.   Aside  from  chromium,   toxic
 pollutants  provided  no  basis  to alter the  subcategories identified
 principally on the basis of raw material and manufacturing processes.

 Same or similar treatment technologies are capable of treating the raw
 wastewaters  associated  with  the  various  industry  segments.   The
 preliminary  treatment  technologies vary with subcategory by presence
 or absence of beamhouse operations and  tanyard  operations  including
 deliming  (ammonia  substitution) and tanning  (chrome recovery).  End-
 of-pipe treatment technology was found to be equally applicable to all
 subcategories after differences in raw waste loads were accounted  for
 by preliminary treatment.  Climate, as noted above, does not adversely
 affect  the  considered treatment process.  There is therefore no need
 to  subcategorize  industry  operations   in   terms   of   wastewater
 characteristics   and  treatability  since  the  same  final  effluent
 concentrations can be achieved by plants in all  subcategories.    Only
 the  mass  limitations  (lb/1,000  Ibs)   vary  according  to water use
 (gal/lb)  in each subcategory.

 The    principal    wastewater    characteristics    considered    for
 subcategorization  were:   1.)   5-day biochemical oxygen demand (BOD5)
 expressed in kilograms  (kg)  per thousand kilograms (kkg)  of  hide,  or
 pounds  (Ib)  per thousand pounds (1000 Ib) ;  and 2.)  flow in litres per
 kg  (gallons/lb)   of  hide.    BOD5  is  associated  with  all  tannery
wastewater;   it  is present,  however, at different levels depending on
 the nature of the raw material and the manufacturing processes.    BOD5


                                 43

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 provides   the    best    measure    of   plant   operation   and   treatment
 effectiveness among  the  wastewater parameters measured,  and more   data
 is   available   for   BOD5 than  for  any  other  pollutant parameter.   Flow
 per  unit of unprocessed  hide weight reflects many  factors,  including:
 1)   type  of  hide   or skin processed;  2) presence of any of  the  three
 major process groupings  (beamhouse, tanyard,  retan-wet finish) in  the
 operation;  3)   degree   of  process  variation;  and  4)  housekeeping
 practices.

 Total suspended solids  (TSS) data  serve to reinforce  the  conclusions
 developed  from BOD5 and flow  in that  presence of  unhairing operations
 substantially increases  the TSS content of raw waste  loads.   Another
 parameter,  chemical oxygen   demand   (COD),  is  also much higher  where
 beamhouse operations are present.  COD is also a measure of refractory
 organic matter  in wastewater,  including some of  the  non-biodegradable
 toxic  pollutants.   Further,  COD is  a good indicator of change,  but
 does not relate directly to the biodegradation occurring in biological
 treatment processes.  However, BODj>, TSS, and COD  are all  reduced  to
 some degree by  the same  tannery wastewater treatment technology.

 Sulfides  and total  chromium are other  pollutant parameters considered
 significant for industry subcategorization.   Trivalent  chromium  is
 recognized  as   an   important  constituent of  tannery wastewater,  hence
 the distinction between  "chrome" and   "non-chrome"  tanneries  in  the
 subcategorization.   The amount of chromium  in the wastewater reflects
 whether a plant operates both  tanning   and   retanning  processes,  or
 merely  retans   partially  processed   stock.   Sulfides originate from
 chemicals used  in the beamhouse unhairing operations and from residues
 of these chemicals in the hides.   The  amount  of  sulfide present in  the
 wastewater reflects  the  type of unhairing process  used.

 Both chrome and sulfide  levels   are   controllable  through  in-plant
 measures  and   efficient  treatment  processes.  In-plant controls  are
 generally dictated on the basis of pollutant  levels  present  in  the
 process  stream.   In the case of  chrome and  sulfide, pollutant levels
 are a function  of the process, which  in  turn   is  reflected  in  the
 subcategorization.   With the proper in-plant controls and preliminary
 treatment in place,  all subcategories can  use   the  same  end-of-pipe
 technologies for effluent treatment.

 EPA  also  considered  a  number  of additional  waste load parameters.
 Among these were nitrites and nitrates,  Kjeldahl  nitrogen,   ammonia,
 total  dissolved  solids,  total  volatile  solids,  oil  and  grease,
 chlorides,  total alkalinity, phenols,  and  fecal  coliform.    In  each
 case,  data  for  these pollutants did not indicate a need for further
 subcategorization on the basis of either these additional  waste  load
 parameters or their treatability.

 The  Agency  found  a  total  of  37   of  the  129  toxic pollutants in
untreated tannery wastewaters.   The  number  present  per  subcategory
                                 44

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varied  from  33  for subcategory one tanneries to 19 for tanneries in
subcategory seven.   (See Tables 6A - 12A, Section 5).

Comparison  among  subcategories  and  constituents,  however,   found
consistency   for   the  acid  fraction  organics   (i.e.,  phenol  and
substituted phenolics) and the inorganics   (cyanide,  chromium,  zinc,
lead, nickel, and copper).  These toxic pollutant groups were found in
the   wastewaters   of   all   sampled  plants;  and  therefore  these
constituents are probably  present  in  all  seven  subcategories.   A
pattern is visible for a single parameter, chromium.  This observation
supports   the   subcategorization   rationale   which   reflects  the
differences  in  chromium  concentrations  present  in  the  untreated
wastewaters.  EPA found no discernable pattern in the concentration of
the   remaining   toxic  pollutants  and  pollutant  groups   (volatile
organics, pesticides, and PCB's, etc.).

Because  the  presence  of  toxic  constituents  varied   within   the
individual  subcategories with no discernible pattern, their treatment
does not appear to be a factor in subcategorization.  Raw  wastewaters
generated by the various segments of the tanning industry are amenable
to the same treatment processes.

Climate,  particularly severe cold, has dictated the type of secondary
wastewater treatment and the specific design  parameters  selected  in
some   instances.    However,   the  ultimate  treatability  of  toxic
pollutants is not influenced by climate, assuming careful design,  and
diligent  operation  and  maintenance  of  extended aeration activated
sludge treatment  systems.   In  fact,   certain  treatment  facilities
operating in the most severe northern climates represent model systems
for the tanning industry (see Section VII).

Differences  in raw waste loading among tanneries are accounted for by
varying the degree of in-plant control  and  pretreatment  rather  than
variation in end-of-pipe technology or  the achievable final effluents.
The  presence  of  beamhouse  operations,  for  example,  requires the
control of sulfide and proteinaceous  material  prior  to  end-of-pipe
treatment.

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                               SECTION  V

                  WATER  USE  AND WASTE CHARACTERISTICS

 The   purpose   of  this section  is to describe the  sources, volumes,  and
 characteristics of wastewaters in the  leather  tanning   and   finishing
 industry.   The   data base  consists of 4,060 data points for  87  plants
 during the  period of  1973 to  1978.  Data  from  the original study were
 used  for   comparison   purposes to  highlight trends and questionable
 data, but were not included in this study.  Detailed  information   for
 individual  tanneries documents this report.

 In  reviewing  this data base,  EPA has  observed variability in the data
 reported by tanners and gathered by EPA.  Some of this variability  may
 be the result  of  differences in production processes  and  scheduling,
 as  well  as   sampling  procedures, analytical  techniques, and possible
 reporting errors.  EPA  has attempted to  ascertain  the  causes  of
 variability and  has taken variability into account in describing  and
 interpreting raw  waste  characteristics presented  below.

 The leather tanning  and   finishing   industry uses  water   in  large
 quantities  for several  purposes:

 1. for soaking and washing  unprocessed hides;

 2. as a medium which allows chemicals  to react with hides/skins;

 3.  as  a carrier for dyes  and  pigments which  impart the desired color
 to the final product; and

 4. for cleaning processing  areas and equipment.

 Figure 2 shows the sequence of  subprocesses  associated  with  tannery
 operations.   This  illustration  also indicates  the origin of solid
 waste and major liquid waste streams for each  process, and the primary
 physical contaminants within each waste stream.

 Recycling and reuse of several  waste  streams  is  a  continuing  and
 growing  trend  in the industry.  Streams such as the spent chrome and
 vegetable tanning solutions, unhairing lime-sulfide  liquor,   and  the
 pickling  solution  are  those  most   frequently considered for reuse,
 recycle,  or  materials  recovery.    Among  U.S.  tanners,  the  chrome
 tanning  solution  is most often managed for reuse.   Pickling solution
 has  also  received  considerable  attention   with  regard  to  reuse.
 European tanneries are reported as giving serious consideration to the
 recovery  of  proteins  from  the beamhouse waste stream; this measure
would reduce tannery waste  loads  while  producing  a  by-product  of
value*.    The  following  discussion  of  subprocesses  as a  source of
wastewater,   however,   will  address   standard   U.S.    manufacturing
 practices.

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                 Figure  £
PRODUCT AND WASTEWATER FLOW FOR GENERALIZED
    LEATHER TANNING AND FINISHING PLANTS
Waste
Added Materials | Processes | Solid and Liquid
Beamhouse
Water 	 	 	 	 	 —
Depilatory Chemicals
Water
Brine and Acid 	
Tanning Agent
Water
Tanyard


—

Water 	 	
Tanning Agent
Water, Bleaching Agents
Dyes & Pigments
Chemical Emulsifiers
Fat liquors, Wate"r
Retan, Color,
Fatliquor

Receive & Store Hides
,
Side


&f — -f —


[Weigh & Sort

	 •) Soak


& Wach


Fleshing — — —
,

- -». Unhair
Pulp
1 	

f,

_ 	

Bate | — — 	
,

	 *| Pickle) 	 	


	 >JTan 	 	


[wring) 	 —


| Split] 	


Grain Portion

| Sh









	 »( Retan | 	 	 —


—*4 Bleaching & Coloring

| Hanging


— *j Fat liquor ing 	 	
|
Setting Out

Dirt, Salt, Blood,
Manure, Nonfibrous
| Proteins, Fleshings,
• Grease
1 Hair, Dissolved Hair
— Pigments, Proteins,
Chemicals
- — Unfixed Chemicals 	 »j
• Unfixed Tanning
| Agents \
p To Split
Tannery
}
To Retan

Unfixed Tanning Agent
Dyes
Pigments
Oils j
1
-. i 	
Drying Pasting Pasting Plate Wash (
| Toggling | Vacuum Vacuum Dust
Finish
Coatings 	 	
— <
	 * 	 1
Conditioning
1
Staking & Dry Milling
1
Buffing 	
1
„ Finishing & Plating
1
| Measure
| Grade |


I Ship |
	 Buffing Dust 	 — — -J
Finish Machine Excess
Spray Machine Baths

r
To Solid Waste Hand]
or Wastewater
Treatment

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 Wastewater   of   various   quantities  and  pollutant  loads  originate  from
 every wet process  in  a tannery.   Depending  on  the  nature  of   the   dry
 finishing operations, such  as embossing, the resulting waste  stream is
 either   intermittent  and  relatively  small,  or  nonexistent.  Historical
 information  and  knowledge of  actual  processing   operations   indicate
 that  tannery wastewaters  contain  soluble and suspended organic matter,
 including  grease  and oils; solids;  inorganic materials such as salt;
 chromium salts;  sulfide;  ammonia;  small  quantities of  nutrients;   and
 in  some cases  coliform.   In   addition   to  chromium,   other  toxic
 pollutants are present in the various waste streams as a result of the
 chemical processes characteristic  of the  tanning  industry.   These
 constituents enter   the  waste   stream  as  proteinaceous matter, hair,
 tissue,  unfixed  chemicals,  tanning agents,  extracts,  dyes,   pigments,
 dirt, grit,  and  manure.

 Water use   and  wastewater  characteristics  throughout the industry are
 discussed in more  detail  below.

 WATER USE

 The volume of water used  (and plant  effluent)  depends   on  the  major
 processes  employed  at   a  specific  tannery.   Variations  in processing
 techniques are recognized in the subcategorization of   the   industry.
 Water use   and  specific  sources  of  wastewater are   discussed, by
 subcategory, as  follows:

 Subcategory  One  (Hair Pulp/Chrome  Tan/Retan-Wet Finish)

 Tanneries in this  subcategory primarily process brine-cured   or  green
 salted   cattlehides  into  finished  leather.   Various amounts  of water
 are   used  in  performing  the  three   wet    processing   operations:
 beamhouse,   tanyard,  and  retan-wet   finish.  Water use  for  typically
 employed  individual  subprocesses   is  described  in  the    following
 paragraphs.

 Soak  and  Wash.   The  purpose  of  this operation is to remove salt,
 restore the moisture content of the  hides,  and   remove  any  foreign
 material  such   as  dirt  and manure.   Brine-cured  hides are soaked and
 washed simply to remove salt, while green  salted  hides  require  the
 removal  of  manure and dirt, as well as salt.   The quantity of manure
 and dirt varies with the  season of the year  and   the  origin  of  the
 hide.    Industry  data   estimate  the  wastewater  volume  from  this
 subprocess to be about  20  percent  of  the  total  wastewater  flow.
 Primary  waste  constituents  from the soak and wash process are BOD5,
 COD,  suspended  solids,   and  dissolved  solids   (including   sodium
 chloride).

Fleshing.   Fleshing  follows  the soak and wash operation if this was
not done previously.   Fleshings are isolated as  a  solid  waste  and,
when  handled  properly,  do not make  a significant contribution to the
total waste loads of a cattlehide tannery.


                                 49

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Unhairing.  Pulping to remove hair involves the addition of  lime  and
sharpeners     (e.g.,    sodium   sulfhydrate)    in   relatively   high
concentrations.  The process dissolves the proteinaceous  hair  enough
to  dissipate  it  in  the unhairing solution.  As reported by various
tanneries, this segment of beamhouse operations generates  between  20
and 38 percent of the total tannery flow, an average of 32 percent for
those facilities reporting such information.  Because of the nature of
this  subprocess,  the BOD5 and other waste constituents (particularly
sulfides and nitrogen) are present in relatively high concentrations.

Bating and Pickling.  The bating subprocess delimes, reduces swelling,
peptizes the fibers, and removes protein degradation products.   Major
chemical  additions are ammonium sulfate to reduce pH to an acceptable
level and enzyme to condition the protein matter.

Following the bating  process,  hides  are  prepared  for  tanning  by
pickling.   Pickling  solutions  contain  primarily  sulfuric acid and
salt,  although  small  amounts  of  wetting  agent  and  biocide  are
sometimes  added,  since protein degradation products, lime, and other
waste material are removed through bating,  the  quantities  of  BOD5,
suspended  solids,  and  nitrogen are relatively low.  Principal waste
constituents are the  acid  and  salt.   Bate  and  pickle  wastewater
volumes, reported as a combined total by several tanneries, range from
9  to  50  percent of the plant flow, an average of 26 percent for the
combined process flow.

Tanning.  Chrome tanning  employs  a  chromium  sulfate  or  a  chrome
tanning  solution  as  the  tanning  agent.   Other chemical additives
include sodium formate and soda ash.  The  chromium  must  be  in  the
trivalent form and must be dissolved in an acidic medium to accomplish
desired results.

For  those  plants  reporting  data,  the  median  and  average  flows
associated with the tanning process were  found  to  be  U.U  and  6.6
percent  of  total plant water use.  The spent chrome tanning solution
represents a relatively low waste load in terms of BOD5 and  suspended
solids;  this  waste  stream,  however,  is  the  principal  source of
trivalent chromium in the plant effluent.

.Some tanneries  prepare  trivalent  chromium  by  reducing  dichromate
solution to the trivalent form, using glucose (molasses)  as a reducing
agent.   The only entry of hexavalent chromium into the plant effluent
is by spillage of unreduced bichromate  or  dichromate  from  reducing
equipment,  or from tanning drums by those very few plants which still
utilize the more traditional "two bath" method of tanning.

Retanning,  Coloring  and  Fatliquoring.   The  chrome  tanned   hides
normally  remain  in  the  same  drums  for  these three subprocesses.
Retanning increases the penetration of tanning solution into the hides
after splitting  and  uses  either  chrome,  vegetable,  or  synthetic
tanning  agents.   Because  retanning  uses  the low concentrations of


                                 50

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 chemicals,  the  wastewater  strength is  not high and  does  not  represent
 a  significant portion of the  total waste flow.

 The   most   variable   process   in   the   tannery is coloring.   There  are
 hundreds of different kinds of dyes,   both   synthetic   and  vegetable
 based.   Synthetic   dyes   are the  most widely used  in the  industry  and
 usually require the  addition  of acid to facilitate  dye uptake  in   the
 leather.  The fatliquoring operation can be  performed either  before or
 after coloring.   Ultimate  use of the leather product dictates the type
 and  amount  of oil required for this subprocess.

 Drying  by   the pasting method requires a small  amount of  water, first
 to prepare  the  mixture and then to wash  it  off.   Even   though   the
 volume  is   very small,   pollutants associated  with the starch can be
 present in  relatively high concentrations Several tanneries report  the
 reuse of paste   mixtures,  which   minimizes   the amount  of   material
 entering the waste stream.

 Process effluent from wet  finishing (retan,  color and fatliquoring)  is
 considered  high-volume, low-strength wastewater, compared  to  the waste
 streams associated with beamhouse  and  tanyard operations.  Because  wet
 finishing   imparts   color  to the process   water,  recycling  is  not
 normally  practiced.   The  wastewater   volumes  from    the    combined
 subprocesses,   reported  as   a  percentage   of total tannery  flow,  are
 highly variable,  ranging from 12 to 30  percent..  Because few  tanneries
 reported flow information  for  these operations,  presentation of   an
 average value could  not be computed.

 Finishing.   Because   leather  finishing  operations are  basically dry,
 they  contribute  the  lowest wastewater  flow   of   any  tannery   process.
 There  is some wet processing, such as  wetting the hides to facilitate
 handling in  the   staking   or   tacking   operations,  but  most   leather
 finishers   do  not   have a contaminated discharge resulting from their
 processing  activities.

 Subcategory  Two  (Hair Save/Chrome  Tan/Retan-Wet  Finish)

 Except  for  the  unhairing  operation,   the  major  processing  steps
 employed  to  convert  cattlehide   into   leather  are similar  to those
 described for Subcategory One.  In the  hair  save unhairing  operation,
 the  hair  is loosened for subsequent machine removal.    The depilatory
 chemicals utilized are  the  same  as   those  characteristic   of  hair
 pulping,  but are present in lower  concentrations.

 The  second step in the hair save operation  is machine removal of hair
 from the hide.   Removed hairs require washing only if they are  to  be
baled and sold;  otherwise they are handled as solid wastes.

The average water consumption of hair save operations is  approximately
 20 percent greater than for hair pulp tanneries.  The higher water use
is  associated  with  machine  removal   and  washing of  the hair.  The


                                 51

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resulting waste  is characterized by a high   alkalinity,  pH,   sulfide,
and nitrogen content.  The reaction of the unhairing solution  with the
proteinaceous    matter   contributes   the   nitrogen.    Other  waste
constituents  include  BODj>,  COD,  suspended   solids,  and  dissolved
solids,  a  portion of which is the sodium chloride remaining  from the
soak and wash operation.  The levels of these pollutant parameters are
significantly less per unit production than  the levels for  hair  pulp
operations.

Subcategory Three  (Hair Save/Non-Chrome 'Tan/Retan-Wet Finish)

The  principal difference between this subcategory and Subcategory Two
is the tanning operation.  Cattlehides leaving  the beamhouse are bated
and pickled in a similar manner, but tanned  with such agents as  alum,
zirconium,  and  other metal salts, as well as syntans, gluteraldehyde,
and formaldehyde.  Vegetable tannins accomplish the major  portion  of
non-chrome tanning.

Spent solutions  from the vegetable tanning process are quite different
from  chrome  solutions.   The reaction rate of vegetable tannins with
the hides is much slower than that associated with chrome.  Because of
the longer contact time, the process normally proceeds  in  vats  with
some  type  of   gentle  agitation.   In some instances, the hides pass
through a series of vats with  varying  solution  strengths.   Process
solution conservation is prevalent due to the cost of tanning  agents.

Portions of the  solution which enter the waste  stream generally result
from  drag-out   or  planned blow-down to maintain the integrity of the
solution.  The semi-batch approach to vegetable tanning  yields  lower
flows  than  those for chrome tanning (Subcategory Two).  With regards
to pollutant parameters, vegetable tanning is a significant source  of
BOD5  and  color.   Although  the retanning and fatliquoring steps are
similar to those employed for  chrome-tanned  hides,  vegetable-tanned
leathers are surface-dyed by spraying the desired color on the leather
surface,

Subcategory Four (Retan-Wet Finish)

Tanneries  in  this  subcategory  receive  previously  tanned hides or
splits for retanning  and  finishing.    Either  chrome,   vegetable  or
synthetic  tanning  agents  can  be  used  for  retanning.   Wastewater
sources for the  wet  finishing  steps  (coloring,  fatliquoring,  and
drying)   are  comparable  to  the description provided for Subcategory
One.   Without the beamhouse and tanyard  operations,  flow  and  waste
loads  (BOD5,   TSS,  COD,  and sulfide)  per unit of production decrease
substantially from those associated with the preceding  subcategories.
The average flow for a retan-wet finish facility is less than one-half
of  the  volume characteristic of tanneries with beamhouse and tanyard
processes.
                                 52

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Subcateqory Five (No Beamhouse)

This subcategory primarily includes plants which tan unhaired pigskins
and pickled  sheepskins.   Tanneries  may  also  receive  pickled  and
unhaired  cattlehides  which  are  subjected  to tanyard and retan-wet
finish processes as outlined for the preceding subcategories.

Unhaired,  pickled  sheepskins  require  fleshing  if  this  has   not
previously  been  done.   Previously  fleshed  skins  usually  require
refleshing  after  tanning.   Pigskins  are  not  subjected  to   this
operation.

Grease  removal  is  necessary  for  both  sheepskins and pigskins and
follows the soak and wash step.  Utilizing the same drums,  degreasing
proceeds  by  one  of two methods:  1) hot water with detergent, or 2)
solvent addition.   In  either  case,  the  grease  is  separated  and
recovered as a by-product having some commercial value.  For pigskins,
the  total  amount  of  grease  removed  from the skin can approach 10
percent of the skin weight.1  The quantity entering the  waste  stream
is  usually  a  small  part  of the total.  In solvent degreasing, the
solvent is recovered for reuse.  BOD5, COD, and suspended  solids  are
other constituents in waste streams generated by this operation.

Prior  to  tanning  pigskins,  the  tanneries must remove the embedded
portion of the hair from the skins.   This  step  is  accomplished  in
drums  containing  a lime slurry and sharpeners; the bating operation,
comparable to the cattlehide process, occurs in the same  drums.   The
pickling step follows to prepare the skins for tanning.

Sheepskins  and  pigskins  may  be  tanned  with  chrome  or vegetable
tannins, although the majority of tanneries utilize the chrome tanning
method.  The conventional practice is to tan pigskins completely, thus
eliminating the need for a retan  operation.   Tanned  sheepskins  are
retanned  in  a  manner  similar  to  cattlehides.   The wet finishing
operations for both types of skins are equivalent to  those  described
for Subcategory One.

Elimination  of  the beamhouse results in lower average flow and waste
loads per unit of production than is typical  for  Subcategories  One,
Two  and  Three;  however,  the  No-Beamhouse segment generates higher
flows and waste loads than tanneries which only retan and  wet  finish
(Subcategory Four).

Subcateqory Six  (Through-the-Blue)

Facilities in Subcategory Six process raw or cured cattlehides through
the  blue  tanned state only.  The remaining steps to produce finished
leather  are  performed  by   other   tanneries   which   characterize
Subcategory Four.
                                 53

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 Unhairing  of  the hides may use either the hair pulp or the hair save
 method.  Hair pulping results in the higher waste  loads,  while  hair
 save  uses  more  water.   Following bating and pickling, the unhaired
 hides are chrome tanned to the blue stage.

 Average wastewater flows for through-the-blue tanneries are lower than
 those for Subcategory Five (No Beamhouse)  tanneries, but greater  than
 facilities  which  only  retan  and wet finish.  The beamhouse process
 increases the pollutant content of the total  plant  waste  stream  to
 levels approaching those observed for Subcategories One and Two.

 Subcatecrory Seven (Shearling)

 This  subcategory  consists  of  tanneries  which process raw or cured
 sheepskins into finished leather with the   hair  (wool)   intact    The
 major processing operations include tanyard and retan-wet finish.

 Prior  to  the  tanning  operation, the skins are soaked and washed to
 cleanse them of foreign matter.   This step requires substantially more
 water for shearlings  than for  unhaired hides or skins.   The  shearling
 hides  are fleshed after washing.   Degreasing follows,  using either of
 the  two  methods  described  for  Subcategory  Five;  however,   grease
 recovery is not normally practiced by shearling tanneries.

 Unlike  unhaired sheepskins, shearling hides are pickled in the manner
 characteristic of cattlehide processing, prior to  tanning.    They  do
 not,   however,  require  liming  and  bating.   Tanning  may  be accomplished
 with  chrome or  vegetable  tannins,   although  the   chrome   method  is
 generally  preferred.    The retanning  and  wet finishing  steps for
 shearlings follow.                                               H

 Because  shearling hides  are processed  with  the  hair  intact,   average
 water consumption  is   more   than   four  times  the volume  per  unit  of
 production observed for  Subcategory  Five,   which essentially   employs
 the   same  processing steps.  The longer hair  and the absence of  grease
 recovery are manor factors  contributing to  the higher waste  loads  for
 suspended  solids  as well  as oil and  grease.

 WASTE CHARACTERIZATIQN

 Background

 The   characteristics  of   untreated  wastewaters  are  based  on-   1)
 ^^f1^1 data, collected from th* industry and various other sources;
 and 2) the sampling program  undertaken  during  the  course  of  this
 study.   EPA  defines  raw waste as the total plant effluent available
 for sampling at the first  access  point  in  the  tannery.   This   is
typically  a  catch  basin  or  wet  well,  frequently equipped with an
 integral screening device.  The raw waste characteristics thus reflect
minimi    ^ ^^ reduction achieved by screening,  which  is  usually

-------
The  Agency  analyzed  the  following  standard  tannery processes and
subprocesses:   beamhouse,  tanyard,  retan,  color,  fatliquor,   and
finishing.   The primary inputs to these operations are water and such
chemicals as lime, sodium sulfide, sodium sulfhydrate, ammonium salts,
enzymes, basic  chromium  sulfates,  vegetable  tanning  extracts  and
compounds, mineral acids, alum, natural and synthetic fatliquors, acid
dyes, some solvent coatings, and sodium chloride.

Depending  on its origin, a waste stream may consist of such materials
as dirt, manure, salt, fleshings, grease, hair, unfixed chemicals  and
tanning  agents, proteins, dyes, pigments, oil, and leather dust.  The
pollutant parameters historically used to characterize the  raw  waste
from  tanneries are flow, BOD5 total suspended solids, oil and grease,
total chromium, ammonia, and  sulfide.   Information  regarding  other
classical  pollutant  parameters,  including  solids and nutrients are
also available from selected sources.  EPA  collected  data  regarding
toxic  pollutants  through  a sampling program described previously in
Section III.  With the exception of chromium, the  analytical  results
represent  first-time  data  generated for toxic pollutants present in
leather tanning and finishing wastewaters.

Relating wastewater volumes and pollutant parameters to production  is
one  way  of  gaining  perspective  on  the waste generated by tannery
operations.  Traditionally, flows as  well  as  "classical"  pollutant
loadings  have  been  related  to production  (defined as the weight of
hides/skins processed)  for  the  purpose  of  normalizing  the  data.
Production level, in terms of hide/skin weight processed per operating
day, for a given plant was computed from the number and average weight
of  hides  reported  by the tannery during year-round operation.  This
approach was taken because the weight of raw material processed  on  a
given  day  is  subject  to variations for both the average weight per
hide/skin and the actual number handled.  The mix of unprocessed  hide
conditions   (green-salted,  brine-cured, fresh, etc.) and the variable
amounts  of  extraneous  matter  attached  to  the  hides  contributed
substantially  to  variations in production levels.  These factors can
also influence the waste flows and loadings.

Wastewater flow is generally presented as the ratio of total volume to
production level per operating day.  Other wastewater  characteristics
(classical  pollutants)  are  expressed in terms of pollutant mass per
1,000 units of production.  The data indicate the  presence  of  toxic
constituents  in  a waste stream; however, a mass relationship between
toxic pollutant levels and production is unclear at  this  time.   The
presence  of  specific  constituents  demonstrates  to some extent the
manufacturing process being employed.

Flow ratios and raw waste loadings based on historical information are
presented for each subcategory.   The  Agency  calculated  "classical"
pollutant  values  from concentrations in milligrams per litre  (mg/1),
flow in gallons per day  (gpd),  and  production  levels  expressed  as
1,000-lb  units  of  incoming  raw  material.  The data base for these


                                 55

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 parameters has been established  by  industry,  governmental  sources,
 sampling, and plant visits.

 EPA  tested  the  raw waste load data base for classical parameters to
 determine the best fit among three types of statistical distributions:
 normal, log-normal and three parameter log.  Flow data were  evaluated
 for  all  subcategories  and pollutant loadings for four subcategories
 (where  sufficient  data  for  statistical  analysis  was  available)
 representing  43  data  sets.   Twenty-five (60 percent)  of these data
 sets were log-normally distributed, including four of seven  low  data
 sets.  In a log-normal distribution, the logarithms of the data points
 are  normally  distributed  thus  allowing application of conventional
 statistical analysis.   The distribution is generally characterized  by
 a  clustering  of most lower and middle range data points with a small
 number of high value data points.  The Agency decided  that  the  log-
 normal  distribution  was  most  representative and appropriate to all
 data sets.  In this form, the most meaningful indicator of the central
 tendancy of the data is  the  geometric  mean;   hence,  all  classical
 pollutant  loads  for   the  seven subcategories of the leather tanning
 industry reflect geometric means (logarithmic averages).

 The Agency sampled a cross-section of the leather  tanning industry  to
 determine  the  presence  and  levels  of  toxic  pollutants,  as noted
 previously by Table 2  (Section III).   Table  5   lists   the  processes,
 hide  material,   and  finished  products  for  each of  the 22 tanneries
 which participated in  the sampling and analysis program.

 Several  toxic pollutants are major ingredients  of   chemicals  used  in
 tannery   processes;  several  others   are  used as solvents   and dye
 carriers.   Many  occur  as minor or trace components in  other chemicals.
 The most heavily used  toxic  pollutant in leather tanning  is  chromium,
 but  there are   several  others   used   in  significant amounts.   These
 include 2

      1.  syntans  based  on naphthalene  and phenol;

      2.  4-nitrophenol  (a biocide, as  well as a waterproofing agent);

      3.  pentachlorophenol  (a preservative and biocide);

      4.  hexachloroethane,  ethylbenzene  and toluene  solvents;

      5.  2,4,6-trichlorophenol  (a biocide);

      6. biocides based on  cresol; and

      7. heavy metals (organometallic dyes).

Other inorganic toxic pollutants found in addition  to  chromium  were
zinc,  lead,  nickel,  copper,  and  cyanide.   The  metals  typically
originate in organo-metallic dyes.  Cyanide also is found in dyes, and
                                 56

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 probably in natural tannins as well.  Many tanners  do  not  know  the
 specific ingredients of the chemical formulations they are using; many
 suppliers do not know the ingredients or purposes of their products Sr
 their uses in tanneries.  These observations are particularly true for
 chemicals  used  only  in  small  quantities.   Some  suppliers sell a
 "service" to the tanneries, i.e.,  each  product  is  prepared  for  a
 tanner to perform a specific function.  Such ingredients are viewed in
 functional  terms  only and not as chemicals reacting in a predictable
 manner •

 As in water use, the levels and types of pollutants  discharged  by  a
 plant  are  a  function of its specific manufacturing processes.  Each
                                             °f  waste"ate*  generation
 Subcatecrory One

 The  primary  constituents of the soak and wash waste stream are BODS
 £i?h fhf!rnded f?lids'  and dissolved solids.   For a cattlehide tannery
 r»n«~ f   ™nt 10S Precedin9 ha« Pulping and chrome tanning, typical
 ranges for BOD5 and suspended solids range from 7 to 22 and 8 to 43 ko
 per kkg of hide (lb/1,000  Ib  of  hide),   respectively.   Because  thl
 incoming  hides  are generally either trine- cured or green-salted,  thl
 salt must be removed in   preparation  for  unhairing!   This  removal
 results  in  relatively high total solids values,  ranging from ulto
 267 kg per kkg of hide  (lb/1,000 Ib of hide) .

 The liming and unhairing process is one of the principal  contributors
 to   the  plant  effluent.    Spent  unhairing liquors contain very hiah
 concentrations  of  proteinaceous  organic  ma?ter,    dissolve^   and
 suspended  inorganic solids,   and  sulfides   (mostly in the dissolved
 form)  in a highly alkaline  solution.   Most sulfides  fo^nd  in  tannlry
 wastewater   comes   from    spent  unhairing   liquors,   although some
 potentially significant amounts,  depending upon ?he  specific procesle!
 and formulations,  carry over  into spent tanning and  retaining liquorl
 «% B0°^fontent °f  ^e waste from this operation may ran^e  from 53 to
 67  kg  (Ib,  per 1,000 kg (Ib,  of  cattlehide  processed.    Concurrently
In the bating of unhaired hides, lime reacts with ammonium sulfate  to
produce  calcium  sulfate, which enters the plant effluent.  The total
nitrogen content of the waste stream varies from 5 to 8  kg  Ub)  per
1,000  kg  (Ib)   of  hide, with ammonia constituting two-thirds  i  Th£
pickling  step  which  follows  generates  relatively  low  Iev4 Is  of
pollutants including BOD5, suspended solids, and nitrogen.

The  chrome  tanning operation generates significant wastes because it
is the manor source of chromium in the total plant effluent;   however
                                                                   '
                                 58

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The wet finishing operations, which include  retanning,  coloring  and
fatliquoring,  generate high-volume, low-strength wastewaters compared
to  the  effluents  from  beamhouse  and   tanyard   processes.    The
temperature  of the retan, color, and fatliquor waste streams is high,
typically exceeding 37.7 degrees C  {100  degrees  F) .l   Use  of  high
temperatures  in  retanning  ensures  maximum chromium uptake, thereby
reducing its discharge to the total waste stream.

As Subcategory One represents  the  largest  portion  of  the  leather
tanning  industry, considerable data were available for characterizing
its wastewaters,  particularly  for  classical  parameters.   Table  6
summarizes  the  classical  parameters,  including  flow,  which  were
employed to characterize the raw loads associated with  this  industry
segment.    The  values  for  flow  and  selected  waste  constituents
represent subcategory averages, flow values are shown in  gallons  per
pound  and values for waste constituents are shown in Ib per 1,000 Ibs
(kg/kkg).   Table  6A  summarizes  the  toxic  pollutants  present  in
Subcategory  One;  constituents  are  characterized by pollutant type,
times found, and concentration.

Subcategory Two

The principal difference between Subcategories  One  and  Two  is  the
method  of  removing  hair  from  cattlehides.   Although water use is
greater for machine removal and  washing  of  hair,  the  waste  loads
associated  with  the  hair  save  process are substantially less than
those for hair pulp  operations.   The  proteinaceous  hair  does  not
dissolve  totally in the unhairing solution for the hair save process.
This results in a lower BODJ5 content in the waste stream, ranging from
17 to 58 kg  (Ib) per  1,000  kg  (Ib)   of  raw  material.   The  total
nitrogen  and  sulfide  content  also  decrease  correspondingly.  The
remaining tannery operations essentially are the same  as  Subcategory
One, thereby contributing similar waste loads.

Tables  7  and  7A  summarize  the  raw wastewater characteristics for
Subcategory Two in terms of classical parameters and toxic pollutants.
Flow and classical pollutants have been normalized based on production
and are presented as subcategory averages.

Subcategory Three

The tanning of cattlehides by non-chrome  methods  distinguishes  this
segment from Subcategory Two.  The most significant difference between
the  raw  waste  loads  of  the  two subcategories occurs in the total
chromium content.  The use of non-chrome tanning  agents  reduces  the
average  chromium level observed in Subcategory Three to approximately
27 percent of that  characteristic  of  Subcategory  Two.   The  small
amount  of chromium present in the effluent from non-chrome tanneries,
compared to Subcategories one and two,  generally  originates  in  the
retanning operations which may require chromium salts.
                                 59

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                  Table 6
Raw Waste Characteristics for Subcategory 1
 Hair Pulp, Chrome Tan, Retan - Wet Finish
Parameter
Gal/lb
BODS
mg/1
lb/1000 Ib
TSS
mg/1
lb/1000 Ib
COD
mg/1
lb/1000 Ib
Oil & Grease
mg/1
lb/1000 Ib
Total Cr.
mg/1
lb/1000 Ib
Sulfide
mg/1
lb/1000 Ib
TKN
mg/1
lb/1000 Ib
Ammonia
mg/1
lb/1000 Ib
Phenol
mg/1
lb/1000 Ib
Number of
Plants
31

16
16

17
17

12
12

14
14

16
16

11
11

10
10

10
10

6
6
l\UII^C \J 1
Number of Individual Geometric
Data Points Data Points M^n
453

205
172

208
175

174
148

75
75

178
148

169
139

58
53

168
138

15
15
0.419 - 10.75

213 - 4300
2.10 - 275

24.8 - 36,100
1.45 - 941

182 - 27,200
6.01 - 612

15.4 - 10,000
0.411 - 261

3.05 - 345
0.062 - 20.5

0.800 - 198
0.021 - 9.94

90.0 - 626
3.17 - 32.5

17.0 - 380
0.417 - 20.6

0.140 - 110
0.007 - 2.87
4.6

1620
62.3

2410
92.3

4640
178

401
15.4

76
2.9

64
2.47

328
12.6

104
3.98

1.0
0.038
                      60

-------
                                  TABLE  6 A

       TOXIC POLLUTANT CHARACTERISTICS OF RAW WASTEWATER
Toxic Pollutant
                              Subcategory  1: Hair  Pulp,  Chrome  Tan,  Retan  -  Wet  Finish
Number of Number of Mean ..
Samples Times Detected Concentration
Volatile Organics
benzene
1 ,2-dichloroethane
1,1, 1-trichloroethane
1,1,2, 2-tetrachloroethane
chloroform
dichlorome thane
1 , 2-trans-dichloroethene
trichloroethene
tetrachloroethene
toluene
1 , 1-dichloroethane
bromodichlorome thane
trichlorofuorome thane
ethylbenzene
1,1, 2-tr ichloroethane
chlorobenzene
Smi-Volatile Organics -
Amines
n-nitrosodiphenylamine
benzidine
1 , 2-diphenylhydrazine
3,3'-dichlorobenzidine
Semi-Volatile Organics -
Ethers

3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3


3
3
3
3



3

1
1
1
3
1
1
1
3
1


2
1




1





15
ND*
Present
10
20
10
30
20
150
275
20
ND
ND
88
10
ND


ND
27
ND
ND


Concentration
Range
i f\ f\ /"\
10-20




10



150-400



88










 bis(2-chloroisopropyl)ether

Semi-Volatile Organics -
 Chlorinated Hydrocarbons
 1,2-dichlorobenzene
 1,3-dichlorobenzene
 1,4-dichlorobenzene
 1,2,4-trichlorobenzene
 hexachlorobenzene
 2-chloronaphthalene
               ND
1             255
               ND
1              54
               ND
               ND
               ND

       * ND = Not detected

       1 concentrations in ug/1
                                             61

-------
Toxic Pollutant
                                 TABLE 6 A Cont'd
Subcategory 1: Hair Pulp, Chrome Tan, Retan - Wet Finish

Semi-Volatile Organics -
Phenols
phenol
total phenol
2 ,4-dichlorophenol
2 , 4-dimethylphenol
2,4,6-trichlorophenol
pentachlorophenol
Semi-Volatile Organics -
Phthalates
bis (2-ethylhexyl) phthalate
dimethyl phthalate
diethyl phthalate
di-n-butyl phthalate
butyl benzyl phthalate
Semi-Volatile Organics -
Miscellaneous
nitrobenzene
isophorone
fluorene
Semi-Volatile Organics -
Polynuclear Aromatics
acenaphthylene
acenaphthene
chrysene
f luoranthene
naphthalene
phenanthrene/anthracene
pyrene
Pesticides & PCB's
alpha and beta BHC
chlordane
Inorganics
cyanide
chromium
copper
nickel
zinc
Number of
Samples


3
3
3
3
3
3


3
3
3
3
3


3
3
3


3
3
3
3
3
3
3

3
3

2
3
3
3
3
3
Number of Mean Concentration
Times Detected Concentration Ranee


3 3700
3 9010
ND
1 Present
2 3390
ND


1 51
1 118
ND
ND
ND


1 425
ND
ND


1 16
1 32
ND
ND
2 46
1 94
ND

ND
ND

2 40
3 79667
3 173
3 1667
3 40
3 427


3000-4400
650-4200

880-5900


















24-67





20-60
43000-18000
50-380
1100-2400
20-60
200-580
                                        62

-------
Parameter
                               Table 7
             Raw Waste Characteristics for Subcategory 2
              Hair Save,  Chrome Tan,  Retan - Wet Finish
              Range of
 Number of   Individual   Geometric
Data Points  Data Points    Mean
Gal/lb
BOD5
mg/1
lb/1000
TSS
mb/1
lb/1000
COD
mg/1
lb/1000



Ib


Ib


Ib
12

7
7

7
7

5
5
254

101
98

82
79

30
27
0.600

140 -
5.45 -

94.0 -
5.26 -

704 -
62.6 -
- 41,294

2790
600

8,580
596

5700
230
5.5

983
45.1

1930
88.3

2610
119.7
Oil & Grease
mg/1
lb/1000
Total Cr.
mg/1
lb/1000
Sulfide
mg/1
lb/1000
TKN
mg/1
lb/1000
Ammonia
mg/1
lb/1000
Phenol
mg/1
lb/1000

Ib


Ib


Ib


Ib


Ib


Ib
5
5

6
6

6
6

5
5

5
5

4
4
30
27

56
53

70
67

56
53

31
28

24
21
49.3 -
2.90 -

0.006
0.001

0.030
0.004

63.0 -
0.617

0.400
0.012

0.440
0.016
620
44.6

- 392
- 6.87

- 300
- 16.1

3650
- 147

- 660
- 38.9

- 6.80
- 0.238
244
11.2

31
1.4

20
0.92

137
6.3

90
4.15

2.2
0.1
                                    63.

-------
                                    TABLE  7 A

                    TOXIC  POLLUTANT CHARACTERISTICS  OF  RAW  WASTEWATER
  Toxic  Pollutant
Subcategory 2: Hair Save, Chrome Tan, Retan - Wet Finish

Number of      Number of      Mean           Concentration
Volatile Organics
benzene
1 , 2-dichloroethane
1,1, 1-trichloroethane
1,1,2, 2-tetrachloroethane
chloroform
dichlorome thane
1 , 2-trans-dichloroethene
trichloroethene
tetrachloroethene
toluene
1 , 1-dichloroethane
bromodichloromethane
trichlorofluorome thane
ethylbenzene
1,1, 2-trichloroethane
chlorobenzene
Semi-Volatile Organics -
Amines
n-nitrosodiphenylamine
benzidine
1 , 2-diphenylhydrazine
3 , 3' -dichlorobenzidine

2 1
2
2 1
2
2 9
*• t.
2
2
2
2 1
2 9
^ z
2
2
2
2 1
2
2 1


2
2
2
2

10
ND*
10
ND
1 tL « ^ * .
26 10-41
ND
ND
ND
10

80 10-150
ND
ND
ND
150
ND
10


ND
ND
ND
ND
Semi-Volatile Organics -
  Ethers	
 bis(2-chloroisopropyl)ether

Semi-Volatile Organics -
 Chlorinated Hydrocarbons
 1,2-dichlorobenzene
 1,3-dichlorobenzene
 1,4-dichlorobenzene
 1,2,4-trichlorobenzene
 hexachlorobenzene
 2-chloronaphthalene
                                ND
                                ND
                                ND
                                ND
                                ND
                                ND
                                ND
                                                       *  ND -  Not  detected
                                                       1 concentrations in ug/1
                                            64

-------
Toxic Pollutant
                                  TABLE  7ACont'd
Subcategory 2: Hair Save, Chrome Tan, Retan - Wet Finish
Number of
Samples
Semi-Volatile Organics -
Phenols
phenol
total phenol
2 , 4-dichlorophenol
2,4-dimethylphenol
2,4, 6-trichlorophenol
pentachlorophenol
Semi-Volatile Organics -
Phthalates
bis( 2-ethylhexyl ) phthalate
dimethyl phthalate
diethyl phthalate
di-n-butyl phthalate
butyl benzyl phthalate
Semi-Volatile Organics -
Miscellaneous
nitrobenzene
isophorone
f luorene
Semi-Volatile Organics -
Polynuclear Aromatics
acenaphthylene
acenaphthene
chrysene
fluoranthene
naphthalene
phenanthrene/ anthracene
pyrene
Pesticides & PCB's
alpha and beta BHC
chlordane
Inorganics
cyanide
chromium
copper
lead
nickel
zinc


2
2
2
2
2
2


2
2
2
2
2


2
2
2


2
2
2
2
2
2
2

2
2

2
2
2
2
2
2
Number of Mean Concentration
Times Detected Concentration Range


2
2
1

1
1


1














1
1
1
1




2
2
2
2
2
2


2876
1920
114
ND
4800
6200


32
ND
ND
ND
ND


ND
ND
ND


ND
ND
ND
2
49
56
1

ND
ND

35
90500
56
700
22
315


252-5500
440-3400





























20-50
31000-150000
55-57
100-1300
5-40
240-400
                                           6.5

-------
 Lesser variations occur for the classical parameters, such as BODS and
 suspended  solids.  Table 8 presents these values along with the waste
 loads for chromium and phenols; Table 8A summarizes  the  presence  of
 other  toxic  pollutants  and  their respective levels for Subcateqory
 Three tanneries.                                                     *

 Subcategory Four

 The tanneries in this  industry  segment  limit  their  operations  to
 retaining  and  wet finishing hides or splits which have been unhaired
 and tanned.   The absence of the beamhouse  process  results  in  lower
 organic  and  sulfide  loadings for this subcategory.  Since retanninq
 may use chrome,  however,  the  total  chromium  levels  in  the  plant
 effluents are significant.                                        u±**^

 Tables 9 and 9A  characterize the tannery wastewaters for classical and
 toxic pollutants.

 Subcategorv  Five

 Subcategory   Five   tanneries  consist  only  of  tanyard and retan-wet
 finish operations  with no beamhouse.   since unhairing  operations  are
 absent  from  these  tanneries,   the  raw waste loads,  including  EOD5
 suspended solids and  sulfide,  are less than  those  for  Subcategorils
 One,   Two, and Three.   Tanyard operations increase classical pollutant
 levels beyond those typical  for  strictly retan-wet finish  facilities.
 Tables  10   and  10A present  the  average values  for classical and  toxic
 pollutants in No Beamhouse tanneries.                             ^oxic

 Subcategorv  six

 Hair   removal and  chrome   tanning   of   cattlehides  are  the    basic
 ?^tl0nS   ?f  Subcate?ory  Six   tanneries.    Relatively high organic
 loads,  as well as  the nitrogen and sulfide  contents,  reflect  beamhouse
 operations;   total  chromium  levels   result    from   chrome   tanninq
 procedures.    Average  raw   waste  loads   for the  major  parameters are
 presented in  Table  11.   Table  11A  identifies the toxic pollutants  and
 their  respective concentrations.

 Subcategorv  Seven

 Tanneries  in this subcategory tan and wet  finish  sheepskins with wool
 intact.  Subprocessing operations eliminate the need for a  beamhouse-
however,  the  amount of foreign matter which must be removed from the
wool creates higher organic waste loads than  those  of  No  Beamhouse
tanneries.   The absence of grease recovery during the degreasing step
is responsible for the higher oil and grease loads.  Chrome taminq is
of^n^f *°r ?hea^linH Processing and results in  significant  levels
of total chromium in the untreated wastewater.
                                 66

-------
                  Table 8
Raw Waste Characteristics for Subcategory 3
Hair Save, NonChrome Tan, Retan - Wet Finish
                              Range of
Parameter

Gal/lb
BOD5
mg/1
lb/1000 Ib
TSS
mg/1
lb/1000 Ib
COD
mg/1
lb/1000 Ib
Oil & Grease
mb/1
lb/1000 Ib
Total Cr
mg/1
lb/1000 Ib
Sulfide
mg/1
lb/1000 Ib
TKN
mg/1
lb/1000 Ib
Ammonia
mg/1
lb/1000 Ib
Phenol
mg.l
lb/1000 Ib
Number of
Plants
16

10
10

10
10

7
7

8
8

7
7

7
7

6
6

5
5

5
5
Number of
Data Points
234

48
48

55
55

40
40

32
32

30
30

29
29

21
21

20
20

16
16
Individual Geometric
Data
0.206

1.00
0.03

28.0
0.767

1080
28.6

2.00
0.016

0.250
0.008

0.100
0.004

130 -
1.94 -

Points
- 38.521

- 7,770
- 203

- 8210
- 362

- 75000
- 2,220

- 1340
- 40.5

- Ill
- 3.939

- 328
- 11.6

1,200
- 49.7

23 - 680
0.433

0.280
0.004
- 10.5

- 100
- 0.786
Mean
4.0

1180
39.2

1680"
56.1

5120
170.9

339
11.3

11
0.38

68
2.26

202
6.75

90
3.0

1.2
0.04
                       67

-------
                                    TABLE  8 A

                  TOXIC POLLUTANT CHARACTERISTICS  OF RAW  WASTEWATER
  Toxic  Pollutant
                               Subcategory 3:  Hair Pulp, Nonchrome Tan, Retan - Wet Finish
Number of Number of Mean
Samples Times Detected Conrent-.raMnp
Volatile Organics
benzene
1 , 2-dichloroethane
1,1, 1-trichloroethane
1,1,2, 2-tetrachloroethane
chloroform
dichlorome thane
1 , 2-trans-dichloroethene
trichloroethene
tetrachloroethene
toluene
1 , 1-dichloroethane
bromodichlorome thane
trichlorofluoromethane
ethylbenzene
1,1, 2-trichloroethane
chlorobenzene
Semi-Volatile Organics -
Amines
n-nitrosodiphenylamine
benzidine
1 , 2-diphenylhydrazine
3,3'-dichlorobenzidine

4 3
4
4
4 1
4 1
4 3
4
4
4 1
4 4
4
4 1
4
4 3
4
4


4
4
4
4

10
ND*
ND
10
24
138
ND
ND
23
12
ND
10
ND
58
ND
ND


ND
ND
ND
ND
Concentration
	 Range 1 	

10-10
J. \s .L \s



10-25
Aw £~ J


10-1 5
•L \J A. J


10-120







Semi-Volatile Organics -
  Ethers	
 bis(2-chloroisopropyl)ether

Semi-Volatile Organics -
 Chlorinated Hydrocarbons
 1,2-dichlorobenzene
 1,3-dichlorobenzene
 1,4-dichlorobenzene
 1,2,4-trichlorobenzene
 hexachlorobenzene
 2-chloronaphthalene
               ND
3             126
               ND
3              20
               ND
               ND
               ND

       * ND = Not detected
49-204

19-20
                                                       1
                                                        concentrations in ug/1
                                            68

-------
                                   TABLE SACont'd
  Toxic Pollutant
Subcategory 3:  Hair Pulp, Nonchrome Tan, Retan - Wet Finish
                              Number of      Number of      Mean
                               Samples    Times Detected  Concentration
                                             Concentration
                                                Range	
Semi-Volatile Organics -
 Phenols	
 phenol
 total phenol
 2,4-dichlorophenol
 2,4-dimethylphenol
 2,4,6-trichlorophenol
 pentachlorophenol

Semi-Volatile Organics -
 Phthalates	
 bis(2-ethylhexyl)phthalate
 dimethyl phthalate
 diethyl phthalate
 di-n-butyl phthalate
 butyl benzyl phthalate

Semi-Volatile Organics -
 Miscellaneous	
 nitrobenzene
 isophorone
 fluorene
                               9050
                               2435
                                 ND
                                 ND
                                915
                               1455
                                 ND
                                 ND
                              Present
                              Present
                                 ND
                                 ND
                                 ND
                                 ND
 51-25000
280-5420
130-1700
 10-2900
Semi-Volatile Organics -
 Polynuclear Aromatics
 acenaphthylene
 acenaphthene
 chrysene
 fluoranthene
 naphthalene
 phenanthrene/anthracene
 pyrene

Pesticides & PCB's
 alpha and beta BHC
 chlordane

Inorganics
 cyanide
 chromium
 copper
 lead
 nickel
 zinc
                                 ND
                                 ND
                                 ND
                                 ND
                                 32
                                  8
                                 ND
                                 ND
                                 ND
                                 80
                               5132
                                380
                                138
                                 61
                                490
  6-59
 60-100
430-10000
100-740
100-200
 40-95
300-700
                                            69

-------
                  Table 9
Raw Waste Characteristics for Subcategory 4
             Retan - Wet Finish
                              Range of
Parameter

Gal/lb
BODS
mg/1
lb/1000 lb
TSS
mg/1
lb/1000 lb
COD
mg/1
lb/1000 lb
Oil & Grease
mg/1
lb/1000 lb
Total Cr.
mg/1
lb/1000 lb
Sulfide
mg/1
lb/1000 lb
TKN
mg/1
lb/1000 lb
Ammonia
mg/1
lb/1000 lb
Phenol
mg/1
lb/1000 lb
Number of
Plants
8

3
3

3
3

3
3

3
3

3
3

3
3

3
3
*/•
*3
3

3
3
Number of
Data Points
68

30
30

28
28

9
9

29
29

24
24

7
7

9
9

9
9

8
8
Individual Geometric
Data
0.622

201 -
1.90

96.0
0.908

1200
32.3

57.5
0.544

1.60
0.045

0.160
0.003

110 -
1.87 -

58.0 -
0.868

0.233
0.003
Points
- 2.580

1600
- 24.2

- 7440
- 82.8

- 4800
- 76.0

- 854
- 12.4

- 381
- 5.50

- 2.40
- 0.680

480
- 7.60

- 160
- 4.50

- 17.0
- 0.289
Mean
1.7

776
11.0

818
11.6

3120
44.2

272
3.85

53
0.75

1.1
0.015

212
3.0

109
1.55

3.9
0.055
                       70

-------
 Toxic Pollutant
                TABLE  9A

TOXIC POLLUTANT CHARACTERISTICS OF RAW WASTEWATER


            Subcategory 4: Retan - Wet Finish
Number of Number of Mean
Samples Times Detected Concentration
Volatile Organics
benzene
1 , 2-dichloroethane
1,1, 1-trichloroethane
1,1,2, 2-tetrachloroethane
chloroform
dichlorome thane
1 ,2-trans-dichloroethene
trichloroethene
tetrachloroethene
toluene
1 , 1-dichloroethane
bromodichlorome thane
trichlorofluorome thane
ethylbenzene
1,1, 2-trichloroethane
chlorobenzene
Semi-Volatile Organics -
Amines
n-nitrosodiphenylamine
benzidine
1 , 2-diphenylhydrazine
3 , 3' -dichlorobenzidine

3 2
3
3
3
3 2
3 2
3
3
3
3 3
3
3
3
3 3
3
3


3 1
3
3
3

10
ND*
ND
ND
10
10
ND
ND
ND
10
ND
ND
ND
80
ND
ND


247
ND
ND
ND
Concentration
I Range 1





10-10
10-10



10-11



10-150








Semi-Volatile Organics -
  Ethers	
 bis(2-chloroisopropyl)ether

Semi-Volatile Organics -
 Chlorinated Hydrocarbons
 1,2-dichlorobenzene
 1,3-dichlorobenzene
 1,4-dichlorobenzene
 1,2,4-trichlorobenzene
 hexachlorobenzene
 2-chloronaphthalene
                                            ND



                                            ND
                                            ND
                                            ND
                                            ND
                                            ND
                                            ND

                                    * ND = Not detected

                                    I  concentrations  in ug/1
                                           71

-------
Toxic Pollutant
                                  TABLE  9A  Cont'd
Subcategory 4: Retan - Wet Finish
Number of
Samples
Semi-Volatile Organics -
Phenols
phenol
total phenol
2 , 4-dichlorophenol
2 , 4-dimethyl phenol
2,4, 6-trichlorophenol
pentachlorophenol
Semi-Volatile Organics -
Phthalates
bis( 2-ethylhexyl ) phthalate
dimethyl phthalate
diethyl phthalate
di-n-butyl phthalate
butyl benzyl phthalate
Semi-Volatile Organics -
Miscellaneous
nitrobenzene
isophorone
f luorene
Semi-Volatile Organics -
Polynuclear Aromatics
acenaphthylene
acenaphthene
chrysene
f luoranthene
naphthalene
phenanthrene/anthracene
pyrene
Pesticides & PCB's
alpha and beta BHC
chlordane
Inorganics
cyanide
chromium
copper
1 j
lead
nickel
zinc


3
3
3
3
3
3


3
3
3
3
3


3
3
3


3
3
3
3
3
3
3

3
3

2
3
3
3
3
3
Number of Mean Concentration
Times Detected Concentration Ranee


2 3200
3 3038
ND
ND
2 573
ND


ND
ND
1 Present
1 Present
ND


ND
ND
ND


ND
1 Present
ND
ND
1 Present
2 120
ND

ND
ND

1 30
3 89000
3 250
3 1300
3 45
3 198


3200
233-5280


573




















106-133






16000-130000
160-330
100-3500
6-100
150-280
                                          72

-------
                  Table 10

Raw Waste Characteristics for Subcategory 5
                No Beamhouse
                              Range of
Parameter
Gal/lb
BOD5
mg/1
lb/1000 Ib
TSS
mg/1
lb/1000 Ib
COD
mg/1
lb/1000 Ib
Oil & Grease
mg/1
lb/1000 Ib
Total Cr.
mg/1
lb/1000 Ib
Sulfide
mg/1
lb/1000 Ib
TKN
mg/1
lb/1000 Ib
Ammonia
mg/1
lb/1000 Ib
Phenol
mg/1
lb/1000 Ib
Number of
Plants
13
10
10
10
10
7
7
7
7
8
8
5
5
4
4
5
5
4
4
Number of Individual Geometric
Data Points Data Points Mean
268
127
127
124
124
64
64
32
32
66
66
13
13
12
12
22
22
20
20
0.672
20 -
3.57
124 -
12.10
140 -
12.3
85.2
1.26
2.80
0.072
0.090
0.001
22.0 -
0.823
6.20 •
0.060
0.112
0.003
- 177
19,800
- 924
37,400
- 7,010
37,900
- 29,200
- 1160
- 894
- 1900
- 17.2
- 6.40
- 0.267
- 160
- 11.9
- 99.0
- 5.02
- 9.90
- 0.705
3.3
1000
27.6
632
17.4
1700
46.8
343
9.45
68
1.86
3.2
0.089
168
4.63
36
1.00
1.2
0.034
                       73

-------
                                   TABLE  10A

                    fOXIC POLLUTANT CHARACTERISTICS OF RAW WASTEWATER
Toxic Pollutant
Subcategory 5:  No Beamhouse
Number of Number of Mean
Samples Times Detected Concentration
Volatile Organics
benzene
1 ,2-dichloroethane
1,1, 1-trichloroethane
1,1,2, 2-tetrachloroethane
chloroform
dichlorome thane
1 , 2-trans-dichloroethene
trichloroethene
tetrachloroethene
toluene
1 , 1-dichloroethane
bromodichlorome thane
trichlorof luorome thane
ethylbenzene
1,1, 2-trichloroethane
chlorobenzene
Semi-Volatile Organics -
Amines
n-nitrosodiphenylamine
benzidine
1 , 2-diphenylhydrazine
3,3'-dichlorobenzidine
Semi-Volatile Organics -
Ethers

3 2
3
3
3
3 3
3 1
3
3 1
3 1
3 2
3
3 1
3
3 2
3
3


3
3
3
3



80
ND *
ND
ND
10
10
ND
10
40
80
ND
10
ND
80
ND
ND


ND
ND
ND
ND


Concentration
Range *

10-150



2-18




10-150



10-150










 bis(2-chloroisopropyl)ether

Semi-Volatile Organics -
 Chlorinated Hydrocarbons
 1,2-dichlorobenzene               3
 1,3-dichlorobenzene               3
 1,4-dichlorobenzene               3
 1,2,4-trichlorobenzene            3
 hexachlorobenzene                 3
 2-chloronaphthalene               3
                                 ND
                                 36
                                 ND
                                 13
                                 ND
                                 ND
                                 ND
                                                         concentrations in ug/1

                                                         ND = Not Detected
                                           74

-------
                                    TABLE10A  Cont'd
  Toxic  Pollutant
Subcategory 5:  No Beamhouse
                               Number  of
                                Samples
               Number of
            Times Detected
  Mean
Concentration
Concentration
   Range
 Semi-Volatile  Organics  -
  Phenols	
  phenol                             3
  total phenol                       3
  2,4-dichlorophenol                 3
  2,4-dimethylphenol                 3
  2,4,6-trichlorophenol              3
  pentachlorophenol                  3

 Semi-Volatile  Organics  -
  Phthalates	
  bis(2-ethylhexyl)phthalate         3
  dimethyl phthalate                 3
  diethyl phthalate                  3
  di-n-butyl phthalate               3
  butyl benzyl  phthalate             3

 Semi-Volatile  Organics  -
  Miscellaneous	
  nitrobenzene                       3
  isophorone                         3
  fluorene                           3

 Semi-Volatile  Organics -
  Polynuclear Aromatics
  acenaphthylene                     3
  acenaphthene                       3
  chrysene                           3
  fluoranthene                       3
 naphthalene                        3
  phenanthrene/anthracene            3
 pyrene                             3

Pesticides & PCB's
 alpha and beta BHC                 3
 chlordane                          3

Inorganics
 cyanide                             3
 chromium                           3
 copper                            3
 lead                              3
 nickel                            3
 zinc                              3
                               6200
                               4630
                                 ND
                                 ND
                               3270
                               3550
                                 ND
                                 ND
                                 ND
                                 ND
                                 ND
                                 ND
                                 ND
                                 ND
                                 ND
                                 ND
                                 ND
                                 ND
                                 27
                                122
                                 ND
                                ND
                                ND
                                ND
                             74000
                               187
                               787
                                15
                              1045
                   390-9500
                  2400-4200
                  3400-3700
                     5-49
                   111-133
                 16000-170000
                  140-260
                   60-1600
                    6-30
                   96-2600
                                            7.5

-------
                               Table 11

             Raw Waste Characteristics for Subcategory 6
                         Through - The - Blue
                                           Range of
Parameter Number of

Gal/lb
BOD5
mg7l
lb/1000 Ib
TSS
mg/1
lb/1000 Ib
COD
mg/1
lb/1000 Ib
Oil & Grease
mg/1
lb/1000 Ib
Total Cr.
mg/1
lb/1000 Ib
Sulfide
mg/1
lb/1000 Ib
TKN
mg/1
lb/1000 Ib
Ammonia
mg/1
lb/1000 Ib
Phenol
mg/1
lb/1000 Ib
Plants
2

2
2

2
2

1
1

2
2

1
1

1
1

1
1

1
1

1
1
Number of Individual Geometric
Data Points Data Points Mean
49

8
8

8
8

5
5

9
9

4
4

4
4

5
5

4
4

1
1
2.00 - 3.61

1310 - 11,000
21.9 - 234

1,220 - 14,500
27.1 - 307

10,500 - 32,900
223 - 669

67.0 - 6,170
1.42 - 177

233 - 397
4.95 - 8.43

137 - 680
2.91 - 14.4

960 - 1780
20.4 - 37.8

382 - 613
8.12 - 13.02

9.60
0.204
2.7

2460
51.3

3870
80.7

6400
133.4

556
11.6

104
2.16

118
2.46

460
9.6

120
2.5

1.5
0.03*
*Estimate

-------
                                   TABLE 11A

              TOXIC POLLUTANT CHARACTERISTICS OF RAW WASTEWATER
PRIORITY POLLUTANT
Subcategory 6: Through-The-Blue
Number of
Samples
Volatile Organics
benzene
1,2-dichloroethane
1 ,1 ,1-trichloroethane
1,1,2,2-tetrachloroethane
chloroform
dichloromethane
1,2-trans-dichloroethene
trichloroethene
tetrachloroethene
toluene
1,1-dichloroethane
bromodi chl oromethane
tri chl orof 1 uoromethane
ethyl benzene
1 ,1 ,2-t ri chl oroethane
chlorobenzene
Semi -Volatile Organics -
Ami nes
n-ni trosodi phenyl ami ne
benzidine
1 ,2-di phenyl hydrazi ne
3,3'-dichlorobenzidine

1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1


1
1
1
1
Number of Mean , Concentration
Times Detected Concentration Range
*
ND
ND
1 Present
ND
1 Present
1 Present
ND
ND
ND
1 Present
ND
ND
ND
1 Present
ND
ND


ND
ND
ND
ND
Semi-Volatile Organics -
  Ethers	
 bis(2-chloroisopropyl)ether

Semi-Volatile Organics -
 Chlorinated Hydrocarbons
 1,2-di chlorobenzene
 1,3-dichlorobenzene
 1,4-dichlorobenzene
 1,2,4-tri chlorobenzene
 hexachlorobenzene
 2-chloronaphthalene
                                 ND
                                 ND
                              Present
                              Present
                                 ND
                                 ND
                              Present
                                                      * ND

                                                      1
                               Not Detected

                          concentrations in ug/1
                                             77

-------
                                   TABLE 11A Cont'd
Toxic Pollutant
Subcategory 6:  Through-The-Blue
Number of
Samples
Semi-Volatile Organics -
Phenols
phenol
total phenol
2 ,4-dichlorophenol
2, 4-ditnethyl phenol
2 ,4 ,6-trichlorophenol
pentachlorophenol
Semi-Volatile Organics -
Phthalates
bis( 2-ethylhexyl ) phthalate
dimethyl phthalate
diethyl phthalate
di-n-butyl phthalate
butyl benzyl phthalate
Semi-Volatile Organics -
Miscellaneous
nitrobenzene
isophorone
f luorene
Semi-Volatile Organics -
Polynuclear Aromatics
acenaphthylene
acenaphthene
chrysene
f luoranthene
naphthalene
phenanthrene/ anthracene
pyrene
Pesticides & PCB's
alpha and beta BHC
chlordane
Inorganics
cyanide
chromium
copper
lead
nickel
zinc


1
1
1
1
1
1


1
1
1
1
1


1
1
1


1
1
1
1
1
1
1

1
1

0
1
1
1
1
1
Number of Mean Concentration
Times Detected Concentration Range


1 Present
1 8480
ND
1 Present
1 Present
ND


ND
ND
ND
ND
ND


ND
ND
1 Present


1 Present
ND
ND
ND
1 Present
1 Present
ND

ND
Present

ND
1 550000
1 100
1 28
1 160
1 980
                                           78

-------
                  Table 12

Raw Waste Characteristics for Subcategory 7
                 Shearlings
                              Range of
Parameter Number of

Gal/lb
BOD5
mg7l
lb/1000 Ib
TSS
mg/1
lb/1000 Ib
COD
mg/1
lb/1000 Ib
Oil & Grease
mg/1
lb/1000 Ib
Total Cr.
mg/1
lb/1000 Ib
Sulfide
mg/1
lb/1000 Ib
TKN
mg/1
lb/1000 Ib
Ammonia
mg/1
lb/1000 Ib
Phenol
mg/1
lb/1000 Ib
Plants
4

3
3

3
3

3
3

3
3

3
3

2
2

2
2

2
2

2
2
Number of Individual Geometric
Data Points Data Points
100

24
24

25
25

19
19

12
12

16
16

10
10

7
7

7
7

10
10
2.31 -

100 -
6.90 -

118 -
13.4 -

370 -
22.6 -

56.0 -
2.52 -

0.020
0.002

0.080
0.008

39.0 -
0.704

08.70
0.146

0.143
0.002
22.1

3,920
445

7650
869

31,500
3,580

1,210
137

- 140
- 14.4

- 68.0
- 0.903

750
- 7.701

- 35.0
- 3.59

- 110
- 11.3
Mean
13.9

349
40.5

388
45

914
106

144
16.7

12.9
1.5

0.2
0.08

53
6.2

13
1.54

0.3
0.03
                        79

-------
                                   TABLE 12A

                   TCVJC  POLLUTANT CHARACTERISTICS OF RAW WASTEWATER
  Toxic  Pollutant
                              Subcategory 7: Shearlings
Number of Number of Mean
Samples Times Detected Concentration ]
Volatile Organics
benzene
1 , 2-dichloroethane
1,1, 1-trichloroethane
1,1,2, 2-tetrachloroethane
chloroform
dichlorome thane
1 ,2-trans-dichloroethene
trichloroethene
tetrachloroethene
toluene
1 , 1-dichloroethane
bromodichlorome thane
trichlorofluorome thane
ethylbenzene
1,1, 2-trichloroethane
chlorobenzene
Semi-Volatile Organics -
Amines
n-nitrosodiphenylamine
benzidine
1 , 2-diphenylhydrazine
3,3' -dichlorobenzidine

2 2
2
2
2 1
2 2
2 2
2
' 2
2
2 2
2
2
2
2
2
2


2
2
2
2

8
ND *
ND
18
16
177
ND
ND
ND
10
ND
ND
ND
ND
ND
ND


ND
ND
ND
ND
Concentration
I Range

5-10



12-20
14-340



9-10












Semi-Volatile Organics -
  Ethers	
 bis(2-chloroisopropyl)ether

Semi-Volatile Organics -
 Chlorinated Hydrocarbons
 1,2-dichlorobenzene
 1,3-dichlorobenzene
 1,4-dichlorobenzene
 1,2,4-trichlorobenzene
 hexachlorobenzene
 2-chloronaphthalene
ND
61
ND
20
ND
ND
ND
19-20
                                                           ND  =  Not  Detected

                                                           concentrations  in  ug/1
                                           80

-------
                                   TABLE  12ACont'd
 Toxic Pollutant
                              Subcategory 7: Shearling
                              Number of
                               Samples
   Number of
Times Detected
  Mean
Concentration
Concentration
   Range	
Semi-Volatile Organics -
 Phenols	
 phenol
 total phenol
 2,4-dichlorophenol
 2,4-dimethylphenol
 2,4,6-trichlorophenol
 pentachlorophenol

Semi-Volatile Organics -
 Phthalates	
 bis(2-ethylhexyl)phthalate
 dimethyl phthalate
 diethyl phthalate
 di-n-butyl phthalate
 butyl benzyl phthalate

Semi-Volatile Organics -
 Miscellaneous
                     91
                    515
                     ND
                     ND
                     ND
                    400
                     93
                     ND
                     ND
                     ND
                     ND
                                                               ND
                                                               ND
                                                               ND
                   180-850
Semi-Volatile Organics -
 Polynuclear Aromatics
 acenaphthylene
 acenaphthene
 chrysene
 fluoranthene
 naphthalene
 phenanthrene/anthracene
 pyrene

Pesticides & PCB's
 alpha and beta BHC
 chlordane
                     ND
                     ND
                     ND
                     ND
                     26
                     36
                     ND
                     ND
                     ND
Inorganics
 cyanide
 chromium
 copper
 lead
 nickel
 zinc
                     10
                  36500
                     78
                     75
                     24
                    345
                    10-10
                  2000-53000
                    35-120
                    70-80
                    20-27
                   190-500
                                            81

-------
Tables  12  and  12A summarize the classical and toxic pollutants found
at shearling tanneries.

SUMMARY

The flow of wastewater per unit production has consistently  decreased
within the leather tanning industry since data was first collected and
reported.  For example, an industry study which served as guidance for
the  Refuse  Act of 1899 Permit Program showed that average flow for a
plant in the current Subcategory One  (Hair  Pulp/Chrome  Tan/Retan-Wet
Finish)  was  73  litres/kg  of  hide  (8.8 gallons/lb).  The technical
evaluation which served as the  basis  for  the  promulgated  effluent
limitations  guidelines (March 1974) indicated that average wastewater
flow for the same industry segment was 53 litres/kg   (6.4  gallons/lb)
of  hide.  This updated study of the industry reveals that the average
wastewater flow for Subcategory One is 38 litres/kg   (4.6  gallons/lb)
of hide.

An  assessment  of  wastewater  data  supplied  by  various  tanneries
indicates that flows well below the subcategory means  are  achievable
for  all  subcategories.   In support of this finding is the fact that
individual plants in each subcategory already operate below  the  mean
flows, as indicated by Table 13.

                               TABLE 13

                     SUMMARY OF SUBCATEGORY FLOWS
               Total Number                            Total Number
               of Plants           Average Flow        Operating Below
Subcategory    Reporting Flow      litres/kg  (gal./lb) Average Flow
1 31
2 12
3 16
4 8
5 14
6 2
7 3
38
46
33
14
28
23
116
(4-6)
(5.5)
(4-0)
(1-7)
(3.3)
(2.7)
(13.9)
16
6
8
4
7
1
2
Section   VII   presents  a  number  of  feasible  water  conservation
techniques which reduce flow.  Further flow reductions may be possible
with the development of innovative conservation measures,  spurred  by
increasing treatment costs.

To  address  the  potential variations of raw waste loads with time of
year, data available for specific years at each tannery were separated
into winter and summer periods.  The  parameters  considered  for  the


                                 82

-------
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                                                                   83

-------
                                 Table 15
Hourly Raw Waste Data  for a Single Cattlehlde Tannery  (Subcategory 1)
    Tannery Bo. 237
Data Takan 9/1-2/76
Tim
7-8 a.m.
8-9 a.m.
9-10 a.m.
10 - 11 a.m.
11 - 12 noon
12-1 p.m.
1-2 P.».
2-3 p.m.
3-4 p.m.
4-5 p.m.
3 - 6 p.m.
6-7 p.m.
7-8 p.m.
8-9 p.m.
9-10 p.*.
10-11 p.m.
11-12
Midnight
12-1 a.m.
1-2 a.m.
2-3 a.m.
3-4 a.m.
4-5 a.m.
5-6 a.m.
Flow (OB)
.0592
.0523
.0443
.0581
.0506
.0460
.0505
.0526
.0347
.0337
.0347
.0250
.0303
.0201
.0241
.0221
.0224
.0243
.0230
.0248
.0352
.0439
.0448
6-7 a.m. : .0648
BODS (ppm)
6190
1620
1320
1650
1370
1550
1080
1660
1030
644
748
862
662
954
1420
430
439
100
4140
2210
1690
2370
2600
3950
Suapcndad
Solida (pom)
6300
2260
1420
2080
2}20
1920
760
1740
260
180
620
240
60
1580
1220
240
480
60
7020
2720
1460
4400
6040
3820
Chromium
Total (ppm)
116
36.8
21.0
20.2
24.8
14.5
17.2
13.0
16.5
76.5
26.5
81.0
34.1
76.2
236
81.5
122
19.3
65.5
201
17.3
53.2
51.5
113
TXN (ppm)
1133
333
196
324
227
249
222
204
151
49
67
58
37
125
141
39
60
20
787
232
187
520
1378
920
PB
12.22
9.48
8.80
9.50
11.60
11.81
9.44
10.36
7.09
7.23
6.57
6.43
6.89
11.83
6.16
6.83
6.60
7.70
12.52
9.56
10.90
12.30
12.34
11.95
Oil and
Graasc (ppm)
770
170
280
160
320
230
270
350
130
160
230
266
58
214
1200
192
110
34
1900
1100
326
635
1380
1200
                                         84

-------
seven  subcategories  include  flow,  BOD5,  suspended solids, oil and
grease,  total  chromium,  and  sulfide.   Data  for   the   untreated
wastewaters    represent   combined   streams   after   screening   or
equalization, if such treatment was in place.  Where appropriate  flow
or  production information was not supplied, it was computer assigned,
based on best available information  and  trends  for  the  individual
plant,  to  generate loadings per unit production.  Table 14 shows the
comparison  of  winter  and  summer  waste  characteristics  for   the
individual  subcategories.   Table  15  shows  the changes in flow and
waste characteristics that occur at a single tannery during one day.

Of the 129 toxic pollutants of interest. Table 16  indicates  that  37
have been identified in the raw wastewaters of the leather tanning and
finishing  industry.   Table  16  shows  the number of different toxic
pollutants that were detected in the  raw  wastewater  of  the  plants
sampled in each subcategory.

                               TABLE 16

                 NUMBER OF DIFFERENT TOXIC POLLUTANTS
                       DETECTED PER SUECATEGORY
Industry
Total
46
Subcateqory
1
33
2
23
3
24
4
20
5
22
6
22
7
19
From  Table  16,  it  is  apparent  that the number of different toxic
pollutants detected is significantly higher  for  those  plants  which
have  beamhouse  operations  and  employ  the  hair pulp process.  The
number of constituents present in the  wastewaters  of  the  remaining
subcategories  fall  within  a very small range, although the specific
pollutants vary with the type of manufacturing process employed.
                                 85

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                               SECTION VI

                   SELECTION OF POLLUTANT PARAMETERS

WASTEWATER PARAMETERS OF SIGNIFICANCE

A thorough analysis of the literature,  industry data and  sampling data
obtained from this study and EPA permit data  demonstrates  that   the
following  wastewater  parameters  are  of significance in the  leather
tanning and  finishing industry:

Conventional and Nonconventional Pollutant Parameters

     Biochemical Oxygen Demand (5-day,  20 degrees C., BOD5)
     Chemical Oxygen Demand
     Oil and Grease
     Sulfide
     Total Suspended Solids  (TSS)
     Nitrogen Content (Ammonia Nitrogen and
      Total Kjeldahl Nitrogen)
     pH and Alkalinity
     Total Dissolved Solids
     Chlorides
     Total Volatile Solids
     Nitrates and  Nitrites
     Fecal Coliforms

Toxic Pollutants

    Organics
      Volatile
      Semi-Volatile
        Basic/Neutral Fraction
        Acidic Fraction

    Inorganics
      Cyanide
      Metals

CONVENTIONAL AND NQNCONVENTIONAL POLLUTANT PARAMETERS

Biochemical Oxygen Demand (BOD)

Biochemical oxygen demand is the quantity of oxygen required  for  the
biological  and  chemical  oxidation  of  waterborn  substances  under
ambient or test conditions.   Material which may contribute to the  BOD
include:    carbonaceous   organic  materials usable as a food source by
aerobic organisms;  oxidizable nitrogen derived from nitrites, ammonia,
and organic nitrogen  compounds  which  serve  as  food  for  specific
bacteria;   and certain chemically oxidizable materials such as ferrous
iron, sulfides,  sulfite,  etc.,  which will react with dissolved  oxygen


                                 87

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 or  which   are   metabolized  by  bacteria.    In   most   leather  tannery
 wastewaters,  the BOD  derives  principally from organic materials,   such
 as  dissolved  or  "pulped11 hair  and  other  extraneous hide  substances,
 and  from ammonia which  is  derived from  residual bating   chemicals   and
 from hydrolytic deamination of  proteinaceous  hair and hide  substance.

 The  BOD of  a  waste  adversely  affects  the dissolved oxygen resources of
 a  body of  water by reducing  the  oxygen available to fish,  plant life,
 and  other aquatic species.  It  is possible  to reach  conditions which
 totally  exhaust the  dissolved   oxygen in   the water, resulting in
 anaerobic conditions  and the  production of  undesirable  gases  such  as
 hydrogen  sulfide  and  methane.   The  reduction of dissolved oxygen can
 be detrimental  to fish  populations, fish growth   rate,   and organisms
 used as  fish   food.   A total  lack of  oxygen due to excessive  BOD can
 result in the death of  all  aerobic aquatic  inhabitants  in the affected
 area.

 Water with  a  high BOD indicates the presence   of   decomposing   organic
 matter  and associated  increased  bacterial  concentrations that  degrade
 its  quality  and  potential    uses.     High   BOD  increases   algal
 concentrations   and  blooms;  these result from decaying organic matter
 and  form the  basis  of algal populations.

 The  BOD5 (5-day BOD)  test   is   used   widely  to   estimate   the  oxygen
 requirements  of discharged  domestic and industrial wastes.  Complete
 biochemical oxidation of  a  given waste   may require a  period  of
 incubation  too long  for practical analytical  test purposes.  For  this
 reason, the 5-day period has  been  accepted  as  standard,  and  the   test
 results  have been  designated as  BODI5.   Specific  chemical test  methods
 are  not  readily  available  for  measuring   the  quantity  of    many
 degradable  substances  and their reaction  products.   In such cases,
 testing relies  on the   collective  parameter,  BOD5.    This  procedure
 measures  the weight of dissolved  oxygen utilized  by microorganisms  as
 they oxidize  or transform the gross mixture of chemical  compounds   in
 the  wastewater.    The biochemical reactions  involved in the oxidation
 of carbon compounds are related to the period  of  incubation.    The   5-
 day  BOD  normally  measures only  60  to  80 percent of the carbonaceous
 biochemical oxygen demand of the sample, and  for many purposes this  is
 a reasonable parameter.  Additionally, it can  be used to estimate  the
 gross quantity  of oxidizable organic matter.

 Some  treated  wastewaters  result  from treatment systems designed to
 remove ammonia  through the nitrification process.   In some cases,  the
nitrifying  bacteria present can exert an additional non-carbonaceous,
 nitrogenous  oxygen  demand   (NOD),  within   the   prescribed   5-day
 incubation   period.    In these instances, special inhibitors are added
to  standard  dilution  waters  to  ensure  the  measurement  only  of
carbonaceous  organic matter.   Ultimate BOD, which is measured after a
 20-day incubation period,  tests  for  aggregate  measurement  of  both
carbonaceous   and   nitrogenous   oxygen  demand  when  nitrification
 inhibitors  are not added to standard dilution  waters.    Ultimate  BOD


                                 88

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can  also be useful in estimating the total dissolved oxygen demand of
wastewaters discharged  to  very  long  receiving  streams  with  long
residence periods.

Chemical Oxygen Demand  (COD)

Chemical  oxygen demand is a purely chemical oxidation test devised as
an alternate method  of  estimating  the  total  oxygen  demand  of  a
wastewater.  Since the method relies on the oxidation-reduction system
of  chemical  analyses,  rather than on biological factors, it is more
precise, accurate,  and  rapid  than  the  BOD  test.   The  COD  test
estimates  the  total oxygen demand (ultimate) required to oxidize the
compounds in a wastewater.  It is  based  on  the  fact  that  organic
compounds,  with  a few exceptions, can be oxidized by strong chemical
oxidizing agents under acid conditions with the assistance of  certain
inorganic catalysts.

The  COD  test  measures  those  pollutants  resistant  to  biological
oxidation in addition to the ones measured by the BOD.5 test.   COD  is
therefore  a  more inclusive measure of oxygen demand than is BODj> and
results in higher oxygen demand values than the BOD5 test.

The compounds which are more resistant  to  biological  oxidation  are
becoming  of  greater  and  greater concern, not only becuase of their
slow but continuing oxygen demand on the resources  of  the  receiving
water,  but  also because of their potential health effects on aquatic
and human life.  Many of these  compounds  have  been  found  to  have
carcinogenic, mutagenic, and similar adverse effects, either singly or
in  combination.   Concern  about  these  compounds has increased as a
result of demonstrations that their long life in receiving waters—the
result  of  a  slow  biochemical  oxidation   rate—allows   them   to
contaminate  downstream  water  intakes.  The commonly used systems of
water purification are  not  effective  in  removing  these  types  of
materials,  and  disinfection  (such as chlorination) may convert them
into even more hazardous materials.

Tannery wastewaters contribute to high COD concentrations and  include
such  constituents  as  extraneous hide substance, complex organic and
inorganic process chemicals, dyes, and vegetable tannins.

Oil and Grease

Because of the nature of the material processed, oil and grease  occur
often in the leather tanning wastewater streams.  They result from the
degreasing  process  used  in  some  tanneries  and from the oils used
directly in the leather processing, especially fatliquoring.  Most  of
these  oil  and  grease  materials  are  animal or vegetable based and
therefore amenable to  removal  through  biological  treatment.    Some
tanneries  us  a  very  small  amount  of mineral based oil; this also
enters the waste stream, although presumably in very small quantities.
It is a more refractory material than are the other kinds of  oil  and


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 therefore    must  be   removed   primarily  by  physical-chemical   waste
 treatment  processes.   These compounds  can   settle   or   float   and  may
 exist  as   solids  or  liquids.   Even  in small quantities oil and  grease
 cause troublesome  taste  and odor  problems.   They produce scum  lines on
 water treatment  basin walls and other  containers and adversely  affect
 fish   and   water fowl,   oil emulsions  may  adhere to the gills  of fish,
 causing suffocation,  and may taint the flesh of  fish that were exposed
 to  waste oil.  oil deposits in  the bottom  sediments of  water can serve
 to  inhibit normal  benthic  growth.  Oil and grease   exhibit an  oxyqen
 demand.

 Oil  and  grease  levels  which  are  toxic  to  aquatic organisms vary
 greatly,   depending   on  the type   of  pollutant   and    the   species
 susceptibility.    In   addition,   the  presence  of  oil  in  water  can
 increase  the  toxicity  of other   substances  discharged into   the
 receiving  bodies of water.

 Sulfide

 A   significant   portion  of alkaline   sulfides  contained in tannery
 wastewater  converts to hydrogen sulfide at  a pH  below   8.0,  resulting
 in  the  release  of  this  gas to  the atmosphere.  This  gas is  odorous,
 and can  damage   property  through  paint   discoloration.   In  sewers,
 hydrogen  sulfide  can   oxidize  to  sulfuric acid,  causing  "crown"
 corrosion  and corrosion  of  equipment in POTW.  This gas   can   also   be
 lethal   to   operation and  maintenance  personnel  in  sewers, and at POTW
 headworks,  primary treatment, and sludge dewatering facilities.   This
 is    particularly  significant  as   a   hazard in   sewer   maintenance.
 Careless mixing  of acid  and sulfide  containing  alkaline   streams   can
 also  be  catastrophic   within  both  tanneries  and  sewers.   Sulfide
 compounds are used extensively in  the  beamhouse   for  the  unhairing
 process, and thus  are found in tannery  effluent.

 Sulfides  impose   immediate and  very  high  dissolved oxygen demand  in
 activated sludge aeration basins, which can  result  in  odor   problems
 during   summer  months when there are  concurrent periods of very rapid
 bacterial oxygen uptake.

 Total Suspended  Solids (TSS1

 Suspended solids include both organic and  inorganic  materials.    The
 inorganic  compounds  include sand,  silt, clay, and toxic metals.  The
 organic  fraction includes such materials as  grease,  oil,  animal  and
 vegetable  waste  products,  and  adsorbed  toxic  organic pollutants.
 These solids may settle out rapidly and bottom deposits  are  often  a
mixture of both organic and inorganic solids.  Solids  may be suspended
 in  water for a time and then settle to the bed of the stream  or lake.
 They  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.


                                 90

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Aside  from any toxic effect attributable to substances leached out by
water, suspended  solids  may  kill  fish  and  shellfish  by  causing
abrasive   injuries/   by  clogging  gills  and  respiratory  passages
screening out light, and by promoting and maintaining the  development
of noxious conditions through oxygen depletion.  Suspended solids also
reduce the recreational value of the water.

Some of the solids generated within a tannery, such as hair or scraps,
are  removed readily by fine screening; other solids settle readily in
clarifiers.  When not removed, these solids can foul  or  plug  pipes,
pumps, and other mechanical equipment.

Nitrogen Content  (Ammonia Nitrogen and Total K-jeldahl Nitrogen)

Ammonia   (NH_3) .   Ammonia  in  surface  and ground waters results from
decomposing nitrogenous organic matter.  It is one of the constituents
of the complex nitrogen cycle.  Ammonia exists in its non-ionized form
only at higher pH levels and is most toxic in this state.   The  lower
the  pH, the more ionized ammonia is formed, and the more its toxicity
decreases.   Ammonia  can  exist  in  several  chemical   combinations
including  ammonium  chloride  and  other  salts.   Ionized ammonia is
generated by spent bating liquors in a tannery.

Evidence exists that ammonia exerts a toxic effect on all aquatic life
depending upon the pH, dissolved oxygen level, and the  total  ammonia
concentration in the water.

Total K-jeldahl Nitrogen (TKN).   Total  Kjeldahl  nitrogen  is ammonia
nitrogen plus organic nitrogen in  wastewater.   Organic  nitrogen  is
derived  primarily from dissolved or pulped proteinaceous hair removed
from hides.  Hydrolysis of this  organic  nitrogen  during  biological
treatment  yields  another  significant source of ammonia.  Hence, TKN
measures the major nitrogen impact upon a  waste  treatment  plant  or
stream  and  is  an  important  measure of the potential environmental
impact of tannery wastewater.

pH and Alkalinity

pH.  Although not a specific pollutant, pH is related to  the  acidity
or  alkalinity  of  a wastewater stream.  It is not a linear or direct
measure of either; however, it may properly be used  to  control  both
excess  acidity and excess alkalinity in water.  The term pH describes
the hydrogen ion—hydroxyl ion balance in water.  Technically,  pH  is
the  hydrogen  ion  concentration  or  activity  present  in  a  given
solution.  pH numbers are the negative logarithm of the  hydrogen  ion
concentration.    A pH of 7 generally indicates neutrality or a balance
between free hydrogen and free hydroxyl ions.   Solutions  with  a  pH
above  7  indicate  that  the solution is alkaline, while a pH below 7
indicates that the solution is acidic.
                                 91

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Knowledge of the  pH  of  water  or  wastewater  aids  in  determining
measures  necessary  for  corrosion  control,  pollution  control, and
disinfection.   To  protect  POTW  from  corrosion,   pH   levels   of
wastewaters  entering the sewerage system must remain above 5.  Waters
with a pH below 6.0 corrode waterworks structures, distribution lines,
and  household  plumbing  fixtures.   This  corrosion  can  add   such
constituents  to  drinking  water  as iron, copper, zinc, cadmium, and
lead.  Low pH waters not only tend to dissolve metals from  structures
and  fixtures but also tend to redissolve or leach metals from sludges
and bottom sediments.  The hydrogen ion concentration also can  affect
the taste of water; at a low pH, water tastes "sour."

Extremes  of  pH  or rapid pH changes can stress or kill aquatic life.
Even moderate changes  from  "acceptable"  pH  limits  can  harm  some
species.   Changes  in  water  pH  increase  the relative toxicity* to
aquatic life of many materials.  Metalocyanide complexes can  increase
a thousand-fold in toxicity with a drop of 1.5 pH units.  The toxicity
of  ammonia similarly is a function of pH.  The bactericidal effect of
chlorine in most  cases  lessens  as  the  pH  increases,  and  it  is
economically advantageous to keep the pH close to 7.

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.

Problems of hydrogen sulfide gas evolution and poor trivalent chromium
removal  can  be  magnified by wastewater pH values below 6.0.  On the
other  hand,  unusually  high  pH  (for  instance  11.0)    can   cause
significant  loss  of  active biomass in biological treatment systems,
especially activated sludge.

Alkalinity.   Alkalinity  is  defined  as  the  ability  of  water  to
neutralize  hydrogen  ions.   It  is  usually expressed as the calcium
carbonate equivalent of the hydrogen ions neutralized.

Alkalinity  commonly  results  from  the   presence   of   carbonates,
bicarbonates,  hydroxides,  and to a lesser extent,  borates, silicates,
phosphates and organic substances.    Because  of  the  nature  of  the
chemicals  causing  alkalinity  and  the  buffering capacity of carbon
dioxide in water,  very high pH values seldom appear in natural waters.

Excess alkalinity as exhibited in a  high  pH  value  may  make  water
corrosive  to  certain  metals,  detrimental  to  most natural organic
materials,  and toxic to living organisms.
*The term toxic or toxicity is used herein in  the  normal  scientific
sense of the word, not the legal.
                                 92

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Leather  tanning  and  finishing  plants   which   include   beamhouse
(unhairing)   operations  will invariably have excess alkalinity due to
the presence of large quantities of lime.   This  alkalinity  provides
buffering  capacity  to  prevent  unacceptably  low  pH,  and enhances
precipitation of many heavy metals, such as trivalent chromium,  found
in tannery and other industrial wastewaters.

Total Dissolved Solids (TDS)

Tannery wastes are high in dissolved solids, the majority of which are
sodium   chloride   and   calcium   sulfate.   Sodium  chloride  comes
principally from desalting from the raw hides by washing and from salt
added in the  pickling  operation.   Calcium  sulfate  can  come  from
several tannery operations, but principally comes from the reaction of
residual  ammonium  sulfate  and  sulfuric  acid with lime used in the
unhairing process.  Dissolved solids  are  particularly  important  in
considering recycle systems; they also have potential impact on stream
life and water treatment processes.

Chlorides (Cl)

The  preponderant  fraction  of tannery dissolved solids is chlorides.
Used  in  conjuction  with  total  dissolved  solids,  this  parameter
indicates  percentages of other dissolved solids.  Chloride content is
important for water reuse considerations.

Total Volatile Solids (TVS)

Total volatile solids (TVS) is an approximate measure of  the  organic
fraction  of  wastewater.   It  is  primarily  useful in analyzing the
potential for biological treatment of the waste.  A high percentage of
volatile solids to total solids in the waste indicates  that  properly
designed   conventional   treatment  processes  may  be  effective  in
pollution control.

Nitrates (NO3) and Nitrites (NO2)

Ammonia, in the presence of dissolved oxygen, is converted to  nitrate
(NO_3) by nitrifying bacteria.

EPA  considers  nitrates  to  be among the objectionable components of
mineralized waters.  Excess nitrates  irritates  the  gastrointestinal
tract,  causing diarrhea and diuresis.  Methemoglobinemia, a condition
characterized by dyanosis and resulting in infant and  animal  deaths,
can  be  caused  by  high  nitrate  concentrations in drinking waters.
Nitrite  (NO_2) , which is an intermediate product  between  ammonia  and
nitrate, sometimes occurs in quantity when depressed oxygen conditions
permit.
                                 93

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 Fecal  Coliforms

 The  presence  in  water  of  fecal coliforms,  which originate  from the
 intestinal tract of  warm-blooded  animals,  indicates   the  potential
 presence of pathogenic bacteria  and viruses.

 The  presence  of  fecal  coliforms in water suggests fecal pollution,
 i.e.,  recent and possibly dangerous   fecal  contamination.   When  the
 fecal  coliform  count  exceeds  2,000  per  100  ml  there  is  a high
 correlation with increased numbers  of  both   pathogenic viruses  and
 bacteria.

 Many   microorganisms, pathogenic to humans and animals,  may be carried
 in surface water, particularly that derived from effluent sources from
 municipal  and  industrial  wastes.   The  diseases  associated   with
 bacteria   include   bacillary   and   amoebic dysentery,  Salmonella
 gastroenteritis,  typhoid  and   paratyphoid    fevers,    leptospirosis,
 chlorea, vibriosis and infectious hepatitis.

 Fecal  contamination  is present in leather tanning wastewater because
 many hides are received with  animal manure and dirt embedded in  them.
 Secondary  biological  treatment can  destroy large quantities of these
 organisms, but disinfection may be necessary where  receiving  streams
 are classified for use as drinking water supplies.
The  129  toxic  pollutants  are  divided  into  three  major  groups:
organics, pesticides and  PCB's,  and  inorganics.   Toxic  pollutants
detected in leather tannery wastes are discussed on the basis of these
three groups.

Table  17  presents  information on the molecular structure, number of
plants where identified, concentration range in the  wastewater,  and,
wherever  possible,  a  brief  description  of leather tannery uses of
these compounds.

Organic Toxic Pollutants

A significant number of  the  organic  toxic  pollutants  appeared  in
tannery  wastewaters  at  concentrations of 1 ppb or higher.  Organics
are  classified  by  the  physical-chemical  properties  which  permit
specific  analytic  schemes  for the analysis of these materials.  The
organic toxic pollutants include compounds in a volatile  fraction,  a
basic or neutral fraction, and an acidic fraction.

Volatile  Fraction.   Table  17  summarizes the volatile organic toxic
pollutants  identified   in   tannery   wastewaters.    Frequency   of
identification  and  concentration ranges for these compounds also are
summarized along with information on common usages.  Eighteen volatile
organic pollutants were found at least once in the sampled  effluents.


                                 94

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Of  these  18,  benzene,  dichloromethane,  ethylbenzene, toluene, and
trichloromethane  appeared  most  frequently  and  in   concentrations
ranging  up  to  100  ppb.   With  the exception of chlorobenzene, the
remaining volatile compounds were halogenated short-chain alkanes  and
alkenes.   The  majority  of  these  compounds  are  typically used as
solvents.

Benzene appeared in raw effluents in levels ranging up to 100 ppb,  in
concentrations   up   to   10   ppb   in  primary  effluents,  and  in
concentrations below 10 ppb in secondary  effluents.   Tanneries  have
used benzene as a general solvent; it is also present as a contaminant
in  other  solvents  such  as  toluene.   Benzene  is used also in dye
manufacturing and in pesticides registered for use on cattle.

The EPA recommended water  quality  criterion  to  protect  freshwater
aquatic  life  from the toxic effects of benzene is 3,100 pg/1 as a 24
hour average, and the concentration should never  exceed  7,000  pg/1.
For saltwater aquatic life the 24 hour average and maximum permissible
concentrations are 920 pg/1 and 2,100 ng/I, respectively.5
Benzene  is  suspected  of  being  a  human  carcinogen.  Studies, for
example, of  the  effect  of  benzene  vapors  on  humans  indicate  a
relationship between chronic benzene poisoning and a high incidence of
leukemia.6  As  there  is no recognized safe concentration for a human
carcinogen, for the  maximum  protection  of  human  health  from  the
potential  carcinogenic  effect of benezene exposure through ingestion
of water and contaminated aquatic organisms, the  recommended  ambient
water concentration is zero. 5

Bromodichloromethane  was  identified  in  the  rawa  effluents  of two
tanneries.  The EPA recommended water  quality  criterion  to  protect
human   health  from  the  toxic  properties  of  bromodichloromethane
ingested through water is 2
Chlorobenzene appeared in in raw, primary,  and  secondary  effluents.
Its  primary  use  is  as  an  organic  solvent, but it functions as a
chemical intermediate in the manufacture of phenol and  aniline.   The
threshold  concentration  of  chlorobenze  in water for detecting both
odor and taste is 20 pg/1.  At pH levels of 3 and below  chlorobenzene
takes up aqueous chlorine to form higher chlorinated benzene rings.

Chloroethane  was  detected  in  one  tannery's  wastewater  which had
undergone primary treatment.  It is used primarily  as  a  solvent  or
refrigerant.   1,2 - Dichloroethane was detected in the raw wastewater
and primary effluent of one plant.

Dichloromethane, also known as methylene chloride, was  found  in  the
raw,  primary, and secondary effluents of a number of plants.  It is a
common solvent, found, for example, in insecticides, and is used  also
as a degreasing and cleaning liquid.
                                 107

-------
 The  recommended criterion to protect freshwater aquatic life is 4,000
 pg/1 as a 24 hour average; the concentration should not  exceed  9,000
 pg/1  at  any  time.  The recommended 24 hour average concentration to
 protect  saltwater  aquatic  life  is  1,900  pg/1,  and  the  maximum
 concentration  is 4,400 Mg/l.  For the protection of human health from
 the toxic properties of methylene chlroide ingested through water, the
 recommended ambient water quality criterion is 2 pg/1.?
 EPA identified ethylbenzene in tannery effluents 23 times,  more  than
 t™  °J:h
-------
protect freshwater and saltwater aquatic life/ the recommended 24 hour
average concentration is 620 jjg/1 and 2,000 pg/1,  respectively;  with
recommended  maximum  concentrations  of  1,400  yg/1  and 4,600 ng/1,
respectively.5

Toluene, a common general organic solvent, appeared in  concentrations
varying  from  trace  to  more  than  100  ppb  in raw wastewater.  In
secondary treatment waters the highest concentration was 50 ppb.

A study using mice showed that toluene is  a  central  nervous  system
depressant  that  can  cause  behavioral  changes  as  well as loss of
consciousness and death at high concentrations.10  Human  exposure  to
toluene for a 2-year period has led to cerebellar disease and impaired
liver  function.10  The recommended water quality criterion to protect
freshwater aquatic life is 2,300  H9/1  as  a  24  hour  average;  the
concentration  should  not exceed 5,200 pg/1 at any time.  The 24 hour
average and maximum concentrations to protect saltwater  aquatic  life
are 100 pg/1 and 230 ng/If respectively.7

Trans - 1,2 - dichloroethylene appeared in raw, primary, and secondary
effluents.   The  compound  is a general organic solvent arid a solvent
for fats and phenol.  The EPA recommended water quality  criterion  to
protect  freshwater  aquatic life is 620 pg/1 as a 24 hour average and
1,400 yg/1 as a maximum permissible concentration.5

1,1,1 - Trichloroethane was found in raw and primary  effluents.   Its
primary use is as a solvent and degreasing agent; trichloroethane act*.;
as  a  solvent  carrier  for  water  and stain repellant compounds, it
exhibits strong solvent action on organics, especially oils,  greases,
waves,  and  tars;  and  it blends with other solvents to reduce their
flammability or provide added solvent properties.

1,1,2  -  Trichloroethane,  also  known  as  vinyl  trichloride,   was
identified  in  the  raw  wastewater  from  one tannery.  It is also a
general solvent for fats and waxes.

Trichloroethylene, another solvent for fats, oils, waxes  and  resins,
was  identified  several  times in raw and primary effluents.  Studies
indicate that exposure to the  compound  increases  the  incidence  of
hepatocellular  carcinoma  in  mice.11   The  compound  also acts as a
central  nervous   system   depressant   in   humans.    Symptoms   of
trichloroethylene   poisoning   include   dizziness,   headaches,  and
respiratory tract irritation.  Severe intoxication can be  fatal,  and
exposure  to  high  levels  can  lead to cardiac arrhythmia, pulmonary
edema, and renal and hepatic dysfunction.11

Trichlorofluoromethane was detected in a trace amount in  the  primary
treatment  effluent  of  one  tannery.   It  is used in aerosals, as a
refrigerant, and in air conditioning.
                                  109

-------
 Trichloromethane,  commonly  known as  chloroform,  appeared  in   the   raw,
 primary,   and   secondary  effluents   of   several  tanneries.    It is  a
 general  solvent, refrigerant,  and cleaning  agent,  and  it  is  registered
 for  pesticide  use  on  cattle.   Lab tests  show  chloroform to be toxic to
 organisms  at various  levels of the food  chain; in  higher  organisms it
 exhibits both  temporary and lasting  effects.   Several  studies indicate
 that  chloroform is carcinogenic to  rats and  mice.12 Human exposure to
 chloroform can lead to liver damage,  hepatic   and  renal  damage,  and
 depression of  the  central nervous system.12

 The  recommended 24 hour average and maximum  concentrations  to protect
 freshwater aquatic life from the toxic effect of  chloroform  are  500
 pg/1  and   1,200   pg/1,  respectively.    The  recommended  water quality
 criterion  to protect  saltwater aquatic life is 620 »g/l as a   24   hour
 average,   with a maximum concentration of 1,400  pg/1.  For the maximum
 protection of  human health  from the  potential carcinogenic effects of
 exposure to chloroform, the recommended  ambient  water  concentration is
 zero.5

 Basic/Neutral   Fraction-    Among  the  basic/neutral   organic priority
 pollutants,  dichlorobenzenes,   naphthalene,   and   the   polynuclear
 aromatics   phenanthrene/anthracene   were the most  often identified.
 Phenanthrene   and  anthracene   co-elute   from gas  chromatograh   (GC)
 analytical  equipment  and  exhibit   very similar mass spectra so  that
 their  identifications represent either 1  compound or some  combination
 of   both compounds.  The basic/neutral compounds typically are used in
 the  manufacture of various  dyes and  in pesticide formulations.

 1,2  - Dichlorobenzene and its  isomer 1,4- dichlorobenzene  were  among
 the  most   common  of  the  basic  neutral  compounds  found  in tanning
 effluents.   Tanneries  use  1,2-Dichlorobenzene  in   a   number   of
 processes.  It  is a solvent for waxes and gums,  a degreasing  agent for
 leather,  an   insecticide,  an   intermediate  in  dye manufacture, and a
 mask for various odors.  1,2- and  1,4-dichlorobenzene were   identified
 as  major   contaminant  chemicals  in  a  hide   curing product used by
 tanneries and  their hide suppliers.  1,4-Dichlorobenzene  is   used  in
 the   manufacture  of  pesticides,  as  an  insecticidal  fumigant  in
 controlling parasites, and in mothproofing wool on sheepskins.

 Unlike the  other dichlorobenzenes,   1,3-dichlorobenzene  was   detected
 only twice  in raw wastewaters.

 Bioconcentration  studies  of   the  dichlorobenzenes  in  the bluegill
 indicate that 1,3-dichlorobenzene concentrates  by  a  factor  of  66
while 1,4-dichlorobenzene concentrates by a factor of 60.13           '

For  1,2-dichlorobenzene,   the  criterion to protect freshwater aquatic
 life is 44  pg/1 as a 24 hour average, and the concentration  should not
 exceed 99 Mg/l  at any time.   For 1,3-dichlorobenzene,  the  recommended
 24  hour average and maximum concentrations  are 310 pg/1 and 700 ug/1
respectively.   The  criterion to protect freshwater aquatic  life  from


                                 110

-------
the  toxic  effects  of  1 ,4-dichlorobenzene are 190 pg/1 as a 24 hour
average concentration, with a maximum concentration of 440
The criterion to protect saltwater aquatic life from the toxic effects
of 1,2-dichlorobenzene is 15 pg/1 as a 24 hour average  concentration;
the  concentration  should  not  exceed 34 pg/1 at any time.  For 1,3-
dichlorobenzene, the recommended criterion is 22 /jg/1  as  a  24  hour
average  and 49 pg/1 as a maximum permissible concentration.  For 1 ,4-
dichlorobenzene,  the  recommended  24  hour   average   and   maximum
concentrations are 15 pg/1 and 34 pg/1, respectively.5

For  the  protection  of human health from the toxic properties of all
isomers  of  dichlorobenzene  combined  ingested  through  water   and
contaminated   aquatic  organisms,  the  ambient  water  criterion  is
determined to be 230 pg/1 total dichlorobenzene. 5

1,2,4 - Trichlorobenzene appeared in the raw wastewater of  one  plant
in  a concentration of 1.8 ppb.  It is commonly used as a dye carrier,
a heat transfer fluid, an intermediate in herbicide  manufacture,  and
as an insecticide against termites.  The compound resists physical and
chemical degradation and accumlates in fatty tissues.

Hexachlorobenzene  was  identified  in  the  secondary effluent of one
plant.  The compound is used as a fungicide and in dye  manufacturing.
Extremely  resistant  to  photochemical  degradation, it also degrades
slowly in the soil,  Hexachlorobenzene bioaccumulates in fatty tissue.

N -  nitrosodiphenylamine  was  the  only  nitrosamine  identified  in
tannery  effluents.   As a class, nitrosamines often are carcinogenic;
they have produced cancer in mammals via all routes of exposure and in
essentially all vital organs.  The nature of toxic response is related
to  the  chemical   characteristics   of   the   particular   compound
administered.  The site of activity depends upon the compound, age and
species  of animal, dosage level, route of administration, and rate of
exposure.14 Toxicological evidence on N-nitrosodiphenylamine  is  such
that  the  compound  is  considered a potential human carcinogen.  For
this reason, to insure the maximum protection of human health from the
potential carcinogenic  effects  of  exposure  to  the  compound,  the
recommended ambient water concentration is zero. 5 Nitrosamines persist
in   soil,   sewage,    and   water.    They   are   characteristically
photosensitive; exposure of ultraviolet (UV)  light split  the  nitroso
group  with  release  of  nitrite  and  secondary  amines.   They  are
characteristically stable under alkaline  conditions;  in  acids  they
undergo  photodecomposition.   N-nitrosodiphenylamine  is  used in the
manufacture of insecticides, rubber, dyes, and solvents.

1,2-Diphenylhydrazine, also known as hydrazobenzene, was  detected  in
the  primary and secondary effluent of one tannery.  It did not appear
in the plant's raw wastewater.   The compound is  primarily  a  special
reagent   in   chemical   laboratory   operations.   There  is  little
information  available  regarding  the  fate  and  effects   of   1,2-


                                 111

-------
 diphenylhydrazine  in the environment, but in one study, 22 percent of
 rats injected with the compound developed tumors.is  For  tne  maximum
 protection  of human health from the potential carcinogenic effects of
 exposure to 1,2-diphenylhydrazine,  the  ambient  water  concentration
 should  equal  zero.   The recommended criterion to protect freshwater
 aquatic life is 17 pg/1 as a 24 hour average concentration and 38 uq/1
 as a maximum concentration.7

 Nitrobenzene was detected in the  raw  and  primary  effluent  of  one
 tannery.    The  concentration decreased from 425 ppb in raw wastewater
 to 29 ppb in the primary effluent.  Nitrobenzene is  used  extensively
 for  the  preparation  of  dye  intermediates  and  as a solvent.   The
 recommended 24 hour average  and  maximum  concentrations  to  protect
 freshwater aquatic life are 480 ug/1 and 1,100 ug/1, respectively.   To
 protect  saltwater  aquatic  life, the 24 hour average criterion is 53
 ug/1; the maximum concentration is 120 ug/1.   For  the  prevention   of
 adverse  effects  due  to  organoleptic  properties of nitrobenzene in
 water,  the criterion is 30 ug/1.

 Benzidine (4,4-diamino-biphenyl),  like other aromatic amines,   results
 from the  reduction of azo dyes in  wastes by hydrogen sulfide or sulfur
 dioxide already present in water.   It is also used directly in the  dye
 industry.   Benzidine undergoes relatively rapid decay in lakewater.   A
 suspected  human  carcinogen,  exposure to benzidine has been linked to
 an increased incidence of bladder  tumors.*•

 3,3»-Dichlorobenzidine (3,3«-dichloro-4,4«-diaminobiphenyl) ,  an inter-
 mediate in the manufacture of  azo  dyes,  was detected in the  secondary
 effluent   of  one   tannery  The compound  has  been demonstrated to be
 carcinogenic in non-human mammals  under   controlled  test  conditions
 Exposure    can  lead  to   the   development  of   various  sarcomas   and
 adenocarcinomas.i7  For the  optimum protection of  human health  from  the
 potential  carcinogenic effects  of  exposure  to  dichlorobenzidine,   the
 ambient water concentration should be zero.7

 isophorone   was  found in   the  secondary  effluents  of  two tanneries.
 Isophorone  acts  as  a  solvent  or   cosolvent  for   finishes,  lacquers,
 resins, pesticides,  herbicides, fats,  oils, and gums.   The  recommended
 24 hour average  and maximum water  quality criterion  for  the protection
 of freshwater  aquatic  life  is  2,100  ug/1 and  4,700  ug/1,  respectively.
 For  the  protection   of  saltwater   aquatic  life the  24 hour  average
 concentration  is 97  ug/1 and the maximum concentration   is   220  uq/1
 To  protect  human   health   from   the  toxic  properties  of  isophorone
 ingested through  water,  the  recommended  criterion   is   460   ug/1  7
 Studies indicate that  human  exposure to concentrations of 10 to  25 ppm
 for a 15-minute period results in  eye, nose, and throat  irritations.i«

 Several   phthalate  esters,  including  dimethyl  phthalate,  diethyl
phthalate, di-n-butyl phthalate, butyl benzyl phthalate,  and  bis-(2-
ethylhexyl)  phthalate,  were  identified  in  tannery  wastewater  at
concentrations up to 200 ppb.  Phthalate esters are  used  extensively


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as  plasticizers and, to a lesser extent, in pesticides and lubricants
in vacuum pumps.

Phthalate esters can harm aquatic and  terrestrial  organisms  at  low
concentrations.   The  compounds  exhibit  teratogenic  and  mutagenic
effects under certain laboratory  conditions.   Of  the  fish  species
tested, the rainbow trout was the least sensitive and the bluegill the
most  sensitive  to  di-n-butyl phthalate.  A cray fish species tested
was  the  least  sensitive  and  a  freshwater  zooplankton  the  most
sensitive of all species tested.4

High  levels  of  phthalate  concentration from water and reproductive
impairment  in   certain   species   are   suggestive   of   potential
environmental  damage.   The  presence  of  these  compounds  in water
affects the growth  and  reproduction  essential  for  maintenance  of
animal populations.

As  a  means  of  protecting human health from the toxic properties of
phthalene esters  ingested  through  water  and  contaminated  aquatic
organisms,   the  recommended  ambient  water  criteria  for  dimethyl
phthalate  and  diethyl  phthalate  are  160   M9/1   and   60   pg/1,
respectively.

Among  the  basic/neutral  compounds  identified  in  various  tannery
effluents  were  ten  polynuclear   aromatic   hydrocarbons   (PNA's).
Naphthalene, phenanthrene, and anthracene were among the most frequent
basic/neutral compounds identified and were detected at levels ranging
from  trace to more than 750 ppb.  The remaining polynuclear aromatics
    acenaphthene,   acenaphthylene,   2-chloronaphthalene,   fluorene,
fluoranthene,  chrysene,  and  pyrene  -  were  present frequently and
usually at low concentrations.  Polynuclear  aromatics  generally  are
used as intermediates in dye manufacture and in pesticides.

On  the  basis  of  present studies, the evidence is not clear whether
individual polynuclear aromatics produce toxicity  or  carcinogeriicity
in  man;  however,  coal  tars, pitch, and other materials known to be
carcinogenic to man contain many of the PNA's that produce  cancer  in
animals.

The  effects  of  naphthalene  poisoning  on humans have been studied.
Naphthalene poisoning can cause convulsions and hematologic changes.19
Reports  also  indicate  that  workers  exposed  to  naphthalene   for
extensive periods of time are likely to develop malignant tumors.19

Naphthalene  bioconcentrates  in  aquatic  organisms  and  reduces  or
interferes with microbial  growth.   It  also  reduces  photosynthetic
rates  in  algae.  Naphthalene accumulates in sediments by a factor as
great as up to two in the concentration in overlying water and can  be
degraded by microorganisms to 1,2-dehydro-l,2-dihydroxynaphthalene and
ultimately to carbon dioxide and water.
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 A  combination  of  fluoranthene  and  benz(a)  pyrene  produced  tumors  in  98
 percent   of  the  mice  tested,  which was more than double the  number  of
 tumors produced in the benz (a)  pyrene control  animals.20

 For  fluoranthene  the water quality criterion  to protect freshwater
 aquatic   life  is 250  »q/l as  a 24 hour average,  and the concentration
 should not exceed 560  jjg/1 at  any  time.   The 24 hour   average and
 maximum concentrations to protect  saltwater aquatic life are  0.30 pg/1
 and  0.69 pg/1, respectively.   For the protection of human health from
 the  toxic properties   of  fluoranthene  exposure   through  water, the
 ambient   water   quality   criterion  should  equal   200  Mg/1-5 For
 acenaphthene the  criterion to  protect freshwater  aquatic life is 110
 pg/1 and 240  pg/1   as  24   hour average and maximum concentrations,
 respectively.  For saltwater aquatic life  the 24 hour   average and
 maximum   concentrations  are   7.5  pg/1 and 17  pg/1, respectively.  The
 ambient water  criterion for the protection  of   human health  is   20
 pg/1.7 For the protection of human health  from the toxic properties  of
 naphthalene ingested through contaminated  aquatic organisms and water,
 the  recommended ambient water  criterion is 143 pg/1.7

 Acidic  Fraction.   Among  the   acidic  fraction   of the organic  toxic
 pollutants, phenols, defined as hydroxy derivatives of benzene and its
 condensed nuclei, and  a  variety  of  substituted phenols,   including
 2,4,6-trichlorophenol  and  pentachlorophenol,  were   identified  most
 frequently, at levels  often exceeding 1 ppm in raw wastewaters.   These
 compounds are typically used to extend raw material storage   life and
 in   bactericide,  fungicide,  and  insecticide formulations.   2,4,5-
 trichlorophenol is a known major constituent   of   a  biocide  used   by
 leather   tanners.   Other  sources which contribute to the significant
 levels of phenols in raw wastewaters  include  synthetic  and  natural
 vegetable tannins  and dye carriers.  Chlorination of such waters can
 produce odoriferous and objectionable tasting  chlorophenols which may
 include   o-chlorophenol,  p-chlorophenol,  2,6-dichlorophenol, and 2,4-
 dichlorophenol.

 Although  described in  the technical literature simply as phenols,  the
 phenol  waste  category  can  include a wide range of similar chemical
 compounds.  In terms of pollution control, reported concentrations   of
 phenols   are  the  result  of   a standard methodology which measures a
 general group of similar compounds rather than specific identification
 of the single compound, phenol  (hydroxybenzene).

 Phenol was identified  33 times  in tannery  effluents,   more  than  any
 other   acidic  organic  pollutant.   Phenolic  compounds  can  affect
 freshwater fishes adversely by direct toxicity to  fish  and  fish-food
 organisms,  by  lowering the amount of available oxygen because of the
 high oxygen demand of compounds, and  by  tainting  fish  flesh.    The
 toxicity  of  phenol  towards   fish  increases as the dissolved oxygen
 level is diminished,  as the temperature is raised, and as the hardness
 is lessened.   Phenol appears to act as a  nerve  poison,   causing  too
much blood to get to the gills and to the heart cavity.21


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Mixed  phenolic  substances  are  especially  troublesome in imparting
taste to fish flesh.  Monochlorophenols produce a bad  taste  in  fish
far  below  lethal or toxic doses.  Threshold concentrations for taste
or odor in chlorinated water supplies have been  reported  as  low  as
0.0003 mg/1.2i

The  human  ingestion  of  a  concentrated  phenol solution results in
severe pain, renal irritation, shock, and possibly death.

Various environmental conditions will increase the toxicity of phenol.
Lower  dissolved  oxygen  concentrations,  increased   salinity,   and
increased  temperature  all  enhance  the  toxicity  of  phenol.   The
recommended water quality criterion to protect freshwater aquatic life
is 600 pg/1 as a 24 hour average, and  the  concentration  should  not
exceed 3,400 M9/1 at any time.7

Although  2, 4-dichlorophenol  (DCP)  appears to be less toxic than the
higher chlorinated phenols, it has demonstrated  toxicity  to  certain
microorganisms,  plants,  and  aquatic  speaies  and  has demonstrated
teratogenicity in nonhuman mammals.22  Fourteen  percent  of  crayfish
exposed   to  1  mg/1  DCP  over  a  10-day  period  died.   When  the
concentration was increased to 5 mg/1 the mortality rate increased  to
34  percent  within  24  hours and 100% within 1 week.  At 10 mg/1 the
mortality rate was 78 percent within 24 hours and 100  percent  within
48  hours.22  The compound has also been shown to have tumor producing
action in mice.22 The  EPA  recommended  water  quality  criterion  to
protect freshwater aquatic life from tainting is 0.4 jjg/1 as a 24 hour
average concentration; the concentration should not exceed 110 M9/1 at
any  time.   To  prevent  adverse  effects  to  human  health  due  to
organoleptic  properties  of  2.4   dichlorophenol   in   water,   the
recommended criterion is 0.5 pg/1.5

2,4,6-trichlorophenol,   like   phenol,  is  an  intermediate  in  the
synthesis of dyes.  This compound can also be  an  impurity  of  2,4,5
trichlorophenol which is a registered biocide used extensively in this
industry.  It was found in high concentrations in raw wastewaters, and
in  some  cases high concentrations in final effluents.  In a study of
genetic activity using an in vitro  mammalian  spot  test  with  mice,
2,4,6-trichlorophenol  exhibited  definite,  although  weak, mutagenic
activity. 23 The recommended 24 hour average and maximum concentrations
to  protect  freshwater  aquatic  life  are  52  jjg/1  and  150  M9/1*
respectively.   To protect human health from adverse effects of 2,4,6-
trichlorophenol, the recommended criterion is 100 jjg/1.?

2, 4-dimethyl phenol has also been  shown  to  have  a  tumor  promoting
action  in  mice.2* For 2, 4-dimethyl phenol,  the recommended criterion
to protect freshwater aquatic life is 38 pg/1 as a 24 hour average the
concentration should never exceed 86
Pentachlorophenol is a registered  and  widely  used  biocide  in  the
leather  industry.   It  was  found  in  high  concentrations  in  raw
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wastewaters and in final effluents.  Several bioassays have shown that
pentachlorophenol is lethal to various species of aquatic  life  at  a
concentration of approximately 200 pg/1.  The lethal concentration for
species  tested  ranged from 195 pg/1 for the brown shrimp to 220 pg/1
for the gold fish.25 The  recommended  24  hour  average  and  maximum
concentrations  to protect freshwater aquatic life are 6.2 jjg/1 and  14
Mg/1, respectively.  To protect saltwater aquatic  life  the  24  hour
average  concentration  is  recommended  to not exceed 3.7 jug/1; at  no
time should the pentachlorophenol concentration exceed 8.5 pg/1.5

A  study  of  genetic  activity  demonstrated  that  pentachlorophenol
exhibited  weak but definite mutagenic activity.25 In nonhuman mammals
the  sublethal  effects   of   pentachlorophenol   poisoning   include
pathological  and  histopathological  changes  in  the kidneys, liver,
spleen,   lungs,   and   brain.25   In   humans,   the   results     of
pentachlorophenol poisoning can range from elevated blood pressure and
rapid  respiration  to  coma  and death.25 For the protection of human
health the ambient water concentration should be no greater  than  140
Mg/l.s

Pentachlorophenol   is  highly  persistent  in  soils.   Reports  have
indicated that the compound can persist in moist soil for at  least  a
12-month period.25

Inorganic Priority Pollutants

Several  of  the  inorganic  toxic  pollutants  were  found in tannery
wastewaters at levels of 1 ppb or  more.   Prominent  among  these   is
chromium  which  is  used in the tanning process.  The other inorganic
toxic pollutants found in tannery wastewater and discussed herein  are
copper, nickel, lead, zinc, and cyanide.

Total Chromium (CrT)

Chromium compounds are used extensively throughout the leather tanning
industry,  and chromium is the most prevalent toxic pollutant found  in
wastewaters in this industry.  Almost all compounds are  used  in  the
trivalent  form;   use of hexavalent chromium in the "two-bath" tanning
process is nearly obsolete.  The prevalent chromium form found in  the
wastewaters  is  trivalent chromium, although hexavalent compounds may
also occur in waste  streams  primarily  from  spillage.   It  is  not
possible,  however,  to  determine  the  distribution  accurately, for
current analytical procedures for chromium cannot always differentiate
between the valence states.

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


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other aquatic life varies widely with the  species,  temperature,  pH,
valence  of  the  chromium,  and  synergistic or antagonistic effects,
especially those of hard water.  Studies show that trivalent  chromium
is  more  toxic  to  fish  of  some types than is hexavalent chromium.
Other studies show opposite effects.  Fish food  organisms  and  other
lower  forms  of  aquatic life are extremely sensitive to chromium; it
also inhibits the growth of algae.   Therefore,  both  hexavalent  and
trivalent   chromium   must   be  considered  potentially  harmful  to
particular fish or organisms.

Fish appear to be relatively tolerant of chromium,  but  some  aquatic
invertebrates  are  quite  sensitive.   Toxicity  varies with species,
chromium oxidation state, and pH.

Chromium concentration factors in marine organisms have been  reported
to  be  1,600  in  benthic  algae,  2,300  in  phytoplankton, 1,900 in
zooplankton, and 440 in molluscan soft parts.26

The chemistry of chromium is very complex, especially in untreated raw
wastewaters where interferences from complexing  mechanisms,  such  as
chelation  by  organic  matter  and  dissolution  due  to  presence of
carbonates, can cause deviation from predicted behavior  in  treatment
systems.   Disposal of sludges containing very high trivalent chromium
concentrations  can  potentially  cause  problems  in   uncontrollable
landfills.   Incineration,  or similar destructive oxidation processes
can produce hexavalent chromium, which in  turn  is  potentially  more
toxic  than  trivalent chromium under certain circumstances.  In other
cases where high rates of chrome sludge application are used, distinct
growth inhibition and plant tissue uptake have been noted.  Therefore,
the use of agricultural land  for  tannery  or  POTW  sludge  disposal
should  not  be  generally adopted in light of the potential for long-
term accumulation and toxicity in soils and plant tissue.

Copper-   Copper  oxides  and  sulfates  are  used   for   pesticides,
fungicides,  and  certain  metallized dyes.  The toxicity of copper to
aquatic life is dependent on the  alkalinity  of  the  water,  as  the
copper  ion  is  complexed  by  anions  present,  which in turn affect
toxicity.  At lower alkalinity  copper  is  generally  more  toxic  to
aquatic  life.   Other  factors affecting toxicity include pH, organic
compounds, and the species tested.  Relatively high concentrations  of
copper  may  be tolerated by adult fish for short periods of time; the
critical effect of copper appears to be its higher toxicity  to  young
or juvenile fish.

In   most   natural   fresh   waters  in  the  United  States,  copper
concentrations below 0.025 mg/1 as copper evidently  are  not  rapidly
fatal  for most common fish species.  In acute tests copper sulfate in
soft water was toxic to rainbow trout at 0.06 mg/1  copper.   In  very
hard  water  the  toxic concentration was 0.6 mg/1 copper.  In general
the salmonids are very sensitive and the sunfishes are less  sensitive
to copper.4


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Copper   appears   in all  soils, and its  concentration  ranges  from  10 to
80  ppm.  In  soils, copper  occurs  in association with  hydrous oxides of
manganese and  iron and also as soluble  and   insoluble complexes  with
organic  matter.   Keeney  and Walsh  (1975)  found that the extractable
copper content of sludge- treated soil decreased  with  time,   which
suggests that  a reversion  of copper to  less  soluble forms.27

Copper   is   essential to the growth of  plants, and the normal range of
concentrations in  plant  tissue is   from  5  to  20  ppm.    Copper
concentrations in plants  normally do not build up to high levels when
toxicity  occurs.   For  example,  the  concentrations  of   copper  in
snapbean  leaves  and  pods was less than 50 and 20 ppm, respectively,
under conditions  of severe copper toxicity.  Even under conditions  of
copper  toxicity,  most  of  the  excess  copper  accumulates in  plant
tissues.  Copper  toxicity  may develop in plants  from application  of
sewage   sludge if  the  concentration  of   copper  in  the  sludge is
relatively high.

The recommended criterion  to protect saltwater aquatic  life  is  0.79
pg/1  and  18  pg/1  as  24  hour average and maximum concentrations,
respectively. 7

Nickel-  Studies  of the  toxicity  of nickel to  aquatic  life  indicate
that  tolerances  vary   widely  and  are  influenced  by  species,  pH
synergistic  effects, and other factors.

Available data indicate  that: (1) nickel in water is  toxic  to   plant
life  at  concentrations   as  low as   100  pg/1; (2)  nickel adversely
affects reproduction of  a  freshwater crustacean at  concentrations  as
low  as  0.095 mg/1; (3)  nickel concentrations as low as 0.31 mg/1 can
kill marine  clam  larvae;  and (4)   nickel seriously affects reproduction
of freshwater  minnow at  concentrations  as low as  0.73  mg/1  and  the
reproduction of Daphnia  at 53
In  nonhuman  mammals  nickel acts to inhibit insulin release, depress
growth, and reduce cholesterol. 2 « A high incidence of  cancer  of  the
lung  and  nose has been reported in humans engaged in the refining of
nickel. 2 s

Lead.  Salmonids and freshwater zooplankton  are  the  organisms  most
sensitive  to  lead.   1  mg/1  was  lethal for trout, while 0.03 mg/1
impaired re productivity in a zooplankton, both  in  soft  water.   The
highest  no-effect  level  on  survival,  growth, and reproduction was
about 0.012 mg/1. 29 in general, the salmonids are  most  sensitive  to
lead  in  soft water, but the influence of pH and other factors on the
solubility  and  form  of  the  lead  have  a  strong  effect  on  the
concentration at which acute toxicities are demonstrated.*

In  humans  lead  poisoning  can cause congestion of the lungs, liver,
spleen, and kidneys. 29 Lead has also caused the formation of tumors in
rats and mice. 29
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To protect  human  health  from  the  toxic  properties  of  lead  the
recommended ambient water criterion for lead is 50 pg/1.5

Zinc.  Toxic concentrations of zinc compounds cause adverse changes in
the  morphology  and physiology of fish.  Acutely toxic concentrations
induce cellular breakdown of the gills, and possibly the  clogging  of
the  gills  with  mucous.   Chronically  toxic  concentrations of zinc
compounds, in contrast,  cause  general  enfeeblement  and  widespread
histological  changes  to  many  organs, but not to gills.  Growth and
maturation are retarded.  In general, salmonids are most sensitive  to
elemental  zinc in soft water; the rainbow trout is the most sensitive
in hard waters. In tests  with  several  heavy  metals,  the  immature
aquatic  insects  seem  to  be  less  sensitive than many tested fish.
Although available data is sparse on the effects of zinc in the marine
environment, zinc accumulates in  some  species,  and  marine  animals
contain  zinc in the range of 6 to 1,500 mg/kg.  Toxicities of zinc in
nutrient solutions have been demonstrated for a number of plants.4

Cyanide.  Cyanide is one of  the  simplest  and  most  readily  formed
organic  molecules.   Cyanide and its compounds are almost universally
present where life and industry are found.  Besides its importance  in
a number of manufacturing processes, cyanides occur in many plants and
animals  as  short  term metabolic intermediates.  Cyanide is found in
certain acid dyes used in the  leather  industry,  such  as  blue  and
green; possibly, it is found also in vegetable tannins.

In  addition  to  the  simple hydrocyanic acid  (HCN), the alkali metal
salts, such as potassium cyanide  (KCN) and sodium cyanide  (NaCN),  are
commonly occurring forms and sources of cyanide.  The latter compounds
dissolved   readily  in  water;  HCN  formation  is  pH-dependent.   A
significant fraction of the cyanide exists as HCN molecules up to a pH
of approximately 8, and the fraction increases rapidly as  the  pH  of
the solution decreases.  When these simple salts dissociate in aqueous
solution,  the  cyanide  ion  combines  with  the hydrogen ion to form
hydrocyanic acid, which is toxic to aquatic life.

The cyanide ion combines  with  numerous  heavy  metal  ions  to  form
metallocyanide  complexes.   The  stability  of these anions is highly
variable.   Those  formed  with  zinc  and  cadmium  are  not  stable;
dissociation  and  production  of  hydrocyanic acid in near neutral or
acidic environments is rapid.  In turn,  some  of  the  metallocyanide
anions  are  extremely stable.  Cobaltocyanide is difficult to destroy
with highly destructive acid distillation in a laboratory.   The  iron
cyanides   are   also  very  stable  but  exhibit  the  phenomenon  of
photodecomposition, and in  the  presence  of  sunlight  the  material
dissociates to release the cyanide ion, thus affecting toxicity.

Cyanide  toxicity  is  essentially an inhibition of oxygen metabolism,
i.e., rendering the  tissues  incapable  of  exchanging  oxygen.    The
cyanogen  compounds  are true noncumulative protoplasmic poisons since
they arrest the activity of all forms of animal life.  Cyanide shows a


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 very  specific  type   of   toxic   action.    It   inhibits   the   cytochrome
 oxidase   system  which   facilitates   electron  transfer  from  reduced
 metabolites to molecular oxygen.   It  does this  by  combining  with   the
 reactive  ferric  ions of  the  catalyst  molecule.

 The   persistence of cyanide   in  water   is  highly  variable.    This
 variability depends  upon the chemical form of cyanide   in the  water,
 the   concentration   of   cyanide, and  the  nature of other  constituents.
 Cyanide   may   be destroyed  by strong   oxidizing agents   such    as
 permanganates  and   chlorine.   Chlorine   is  commonly  used  to oxidize
 strong cyanide solutions to  produce carbon dioxide and  nitrogen;   if
 the   reaction  is not carried through to  completion, cyanogen chloride
 may remain as  a  residual.  This material  is also toxic.   If  the pH   of
 the   receiving  waterway  is acidic   and the  stream is  well aerated,
 gaseous   hydrogen  cyanide   may evolve   from  the waterway to    the
 atmosphere.    At low  concentrations and with acclimated microflora,
 cyanide may be decomposed  by microorganisms  in  both  anaerobic   and
 aerobic environments or  waste treatment systems.

 A  review of  the   pertinent   literature concluded that free cyanide
 concentrations ranging from  50  to  100 ug/1   as cyanide  have  proven
 eventually  fatal  to  many  sensitive fish; levels much above 200 ug/1
 probably  are rapidly fatal to most fish species.   Among  the  species
 studied   were  brook trout (Salvelinus fontinalis), brown trout (Salmo
 trutta),  smallmouth  bass   (Micropterus  dolomieu),  bluegill  (Lepomis
 machrochirus), and fathead minnows (Pimephales  promelas).

 Some  information  on  chronic  or sublethal effects of  cyanide is also
 available.  Among the findings  were:   increased intestinal   secretions
 in  the   fish,   Cichlasoma bimaculatum. at concentrations as low as  20
 ug/1 and  reduced swimming capability  at   concentrations   of  40  ug/1.
 Exposure  to   cyanide  concentrations  as  low   as 10 ug/1 reduced the
 swimming  ability or  endurance of brook trout,   Salvelinus  fontinalis.
 Growth,   or  food  conversion   efficiency of  coho salmon, Oncorhynchus
 Kisutch.y  decreased at hydrogen  cyanide   concentrations  of  20  ug/1.
 Small  freshwater  fish  of  the family Cichlidae exposed to a cyanide
 concentration  of 15 ug/1 lost weight  more  rapidly  than  the  control
 fish in water  free from cyanide.

To  protect  freshwater  aquatic  life  the  recommended water quality
criterion is 1.4 pg/1 as a 24 hour average concentration;  the  maximum
 concentration  should not exceed 38 pg/1 at any time.   The criterion to
protect  human  health  from  the toxic properties  of cyanide ingested
through water and contaminated aquatic organisms is 0.2 mg.CN-/!.?
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                           SECTION VII

                 CONTROL AND TREATMENT TECHNOLOGY

 PRODUCTION

 is section describes waste treatment technology currently in use and
 ailable for use in the leather tanning and finishing industry.   Two
 neral   approaches  to  pollutant  reduction   are   in-plant  process
 ntrols and  end-of-pipe  effluent  treatment   systems.   End-of-pipe
 eatment  approaches  include:   (1) preliminary treatment and primary
 eatment;  (2) secondary treatment; and  (3) advanced  waste treatment.

 e term pretreatment as used in the proposed regulations  is  defined
  include  in-plant  controls   (Level   1),  preliminary treatment  of
 gregated streams   (Level   2),  and  primary   treatment  of  combined
 reams  by  coagulation-sedimentation   (Level  3).  These technologies
 e  intended  to  precede   either  separate  industrial   "secondary"
 ological treatment by direct dischargers, or  discharge to a publicly
 ned  treatment works  (POTW).  It is necessary to reduce shock  loads,
 otect the biological system, remove the  suspended solids that  resist
 eatment, remove heavy metals  (including  chromium which would   render
 TW  sludges  unacceptable  for  agricultural  use),  prevent damage  to
 wer  lines,  and  reduce   health  and  life   hazards   in   sewerage
 intenance.

 econdary"  treatment,  typically  a biological treatment process,  is
 tended for use in this  industry  to  remove   biodegradable  organic
 terial  subsequent  to  pretreatment  as defined   above.   A   major
 iduction of BOD5, suspended solids, phenols,   some   related  phenolic
 impounds,  and certain other toxic organic pollutants is accomplished
 L "secondary"  treatment,  as  well  as   a  significant  degree   of
 .trification.

 Ivanced  waste  treatment,  typically following primary and secondary
 •eatment processes, includes technologies which remove  residuals   of
 ispended  solids,  heavy metals, and dissolved organic compounds, and
 reduce an  effluent  of  high  clarity   and  very  low  conventional,
 mconventional, and toxic pollutant content.

 irrent Practices

 irrent  practices  in the tanning industry range from no treatment  of
 istewater to  several types  of  "secondary" treatment.   Because   POTWs
 rovide   secondary   treatment,  effluent quality   requirements for
 idirect dischargers to municipal sewer   systems are less  stringent
 lan  for  tanneries  that   discharge  directly to surface waters.   A
 irvey of 89 wet-process tanners indicates that 12  percent  of the
 idirect   dischargers   have  no  pretreatment, whereas  all   direct
Lschargers surveyed have at least primary treatment  and some form   of
?condary  treatment, which  may still need upgrading  to meet either  or


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both BPT and BAT  limitations.   With  increasing  numbers  of  stat<
imposing more stringent water quality limitations in NPDES permits fc
POTW's, there is a trend toward some pretreatment by all tanners.

The  information collection forms and questionnaires, site visits, ai
sampling visits of wet processors have provided a profile  of  currer
control  practices  in  the  leather  tanning  industry.  Most tannei
discharge to municipal treatment plants.  These  indirect  discharge!
comprise  170 tannery operations, or about 90 percent of the industry
Of these dischargers, 88 percent provide preliminary  treatment,  one
fifth of the treatment operations consisting of coarse screening onl}
The  remaining  12 percent do not provide preliminary treatment.  Nor
of the indirect dischargers provide secondary treatment.

Eighteen plants (about 10 percent of  the  industry)  discharge  thej
wastewater  directly  to  surface waters.  All 18 provide some type c
secondary treatment, five using activated  sludge  treatment  and  th
other 13 using lagoons or other treatment methods.

One plant, now closed, operated a physical-chemical treatment system.

Waste Control and Treatment Considerations

The  pollutants  found  in  leather  tanning and finishing wastewater
differ little from those in wastewaters of many other  industries  an
can be treated by conventional methods for suspended solids reductior
oil  and  grease  removal,  pH  control, and BOD5 reduction.  Specifi
constituents peculiar to certain tanning processes, such as the  toxi
pollutants  chromium  and  phenol,  and the nonconventional pollutant
sulfide, TKN, and ammonia can  be  removed  with  available  treatmen
methods currently practiced by the industry.

Tannery  waste  treatment cannot overlook the interrelationship of th
different media (i.e. air, water, and land)  for  pollutant  discharge
for example, coagulation-sedimentation and sludge dewatering produce
waste  product  for  land  disposal.  If a chromium tanning process i
used, this waste will contain large quantities of trivalent  chromium
and  care  must be exercised in managing the waste disposal to preven
leachate contamination of ground or surface waters.   The  practice  o
chromium reuse or recovery within the plant should reduce the chromiu
content of the sludge.

Tannery  wastes can create or contribute to the following problems fo
POTW's and separate industrial wastewater treatment facilities:

     1.   discharge of significant concentrations and mass
         of toxic pollutants:
     2.   large pieces of scrap hide and leather clogging
         or fouling operating equipment;
     3.   excessive quantities of hair and other small
         screenable solids;


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    4,   highly acidic or alkaline waste streams;
    5.   wastewater flow surges;
    6.   excessive loadings of suspended and settleable
        solids and BODJ5, consistently or in surges;
    7.   odors, facilities corrosion, very high dissolved
       oxygen demand in biological treatment system aeration
       basins, and hazardous gas generation from sulfide
       bearing wastes
    8.   a problem with disposal of sludges containing
        chrome; and
    9.   pass through of ammonia nitrogen.

ich  of  the  problems  outlined  can  be  reduced  significantly  or
Liminated  by  applying pretreatment technology in leather tanneries.
Lne screening effectively removes hair, fibers,  and  scrap  material
:om  wastewater  and  is  available in many different configurations,
Dme of  which are  particularly  effective  on  tannery  type  wastes.
greening  equipment  also must be installed, operated, and maintained
roperly to function well.

iste streams from specific  processes  in  tanneries  can  be  highly
::idic  or  alkaline.   If  such  streams  are  discharged  without pH
ljustinent or mixing with a different neutralizing stream,  the  waste
bream may create problems within the sewer or at the treatment plant.
  pH  control  mechanism  of  holding and mixing various wastes or of
irectly adjusting the pH of the waste  is  easily  implemented  as  a
retreatment technology.

Low and waste loading surges, which can be particularly disruptive to
iological  treatment  systems  employed by POTWs, can be minimized by
Dualizing the rate of flow or  waste  loading  discharge.   If  space
imitations  at  a  tannery  preclude  an equalization tank, discharge
cheduling, as practiced by at  least  one  tannery,  can  reduce  the
agnitude of these surges.

atch  basins,  wet  wells, and other preliminary treatment facilities
hat provide a retention time and space for solids separation from the
aste  stream  can  be  very  effective  if  properly   designed   and
aintained.   Such a facility requires regular maintenance in order to
perate  consistently and effectively.

he potential problems in disposing of municipal sludge that  contains
hromium  can be alleviated by chromium removed by tanneries.  In this
anner,  a smaller quantity of sludge containing a higher concentration
f chrome is more easily disposed  of  in  a  controlled  environment.
hrome  recovery  and  reuse technology is available and in use by the
ndustry.  This substantially reduces the chrome content of the  waste
tream and of sludges generated in treatment of these wastes.

n  its   evaluation  of  available  treatment  technologies,  EPA  has
ttempted to do the following:


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      1.    Identify methods of substantially  improving  the  currently

           treatment l^s.^0™™  °f  m°St  ^^  wastewate^

      2.    Present  information  on  recycle,   recovery,   and/or  reuse

           r*liShi29i2 •  3S 7iabl?T   ?°St  effective,  established,  and
           reliable options for pollution control.

      3.    Describe the performance of in-place  preliminary  treatment
           and  secondary  treatment technologies on  the  toxic pollutants
           found in tannery wastewaters.

      «.    Present information on the effectiveness of  advanced  waste
           treatment technologies on pollutants as 1) demonstrated in
           use,  2)  transferable from   a  related use  or   experimental
           work,   or 3) thought to be effective based on a  knowledge of
           chemical  process  technology   and   of  the  similarity   of
           structure.       <*emicals   of   similar  molecular  size  and

This  discussion  groups the  pollution control technologies  by  the  point
?hPaPfl^ati?":   in-Plant'  Preliminary   treatment,  and   end-of-pipe
The   distinction  between the  first two may blur  in  some instances-  but
the focus  of the  first is   on   in-plant   waste  control ,   whlrell '  the
second  group  of   technologies  typically involves  waste treatment  and
pollution  control  preparatory  to discharge into  a municipal   sewer   or
into   an  industrial  secondary treatment  system.   Each   treatment
approach is discussed with  a description  of   equipment!   examples   of
systems currently  being used,  and reduction levels  expected?

IN-PLANT CONTROL TECHNOLOGY -  LEVEL _1

Appraisals  of  plant  waste  production  must   first  investigate the
??™ aC^ng °yCle f°r any Codifications which  can reduce  the  waste
~SL        concentration of waste constituents.  Particular emphasis

thf ?otal wfsteCstreamh°S? faCt°rS ^iCh ^ Pr°blems in treatment "I
tne total waste stream,  in  some  instances,   reuse  or  recoverv  of
                                                                    of
                                   can
Process changes and  waste  stream  segregation  are  two  methods  of
pollutant  reduction  and/or control essential to achieving

provides ^useful  ^g"1"^ ^ "6 "-3tionnaires  from
The following steps can often reduce pollutants and the costs of waste
treatment:                                                       waoi_t:

     1.   process changes;
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     2.   substitution  of  process  ingredients;

     3.   water  conservation  and reuse;

     4.   repair and  replacement of  leaky or  faulty equipment;

     5.   installation  of  automatic  monitoring  devices  to  detect
         abnormal  quantities of selected constituents  in  waste
         effluents;

     6.   recovery  and  reuse  of process  chemicals;  and

     7.   in-plant  treatment  to remove a specific waste
         constituent.

'rocess  Changes

'rocess  changes have been difficult to  make  in this industry   because
>f  the   diverse  tanning methods  employed.   While tanning operations
;raditionally employed the batch  system, it  is possible that  more  of
:he  chemical applications as well  as the washing  and  rinsing  could be
landled  more  efficiently  on  a counter-current  continuous   flow  basis.
This  would   achieve  maximum utilization  of all active ingredients,
.eaving  only  concentrated wastes  of small volumes   for treatment  and
lisposal.  Substitution   of effluents  from   one process for make-up
/ater in another  generally   is   feasible at   some points within  a
:annery.  Before  tanneries can  make this change however, they must
establish the quantity and pollutant content  of  water  required  for
?ach operation.

Substitution  of Process Ingredients

Chemical  ingredients   of low pollution potential for those which are
problem  pollutants often   can be  used  to  advantage in  industrial
processes.  Difficulties  caused by  high concentrations of contaminants
Ln  spent tan   liquors  from vegetable  tanning   processes have been
Lessened  through  recovery   and  reuse  of  those  spent  liquors  in
segregated,   concentrated waste  streams,  and through   the   use  of
synthetic tanning  agents  (syntans).  A  number of process  chemical
substitution  opportunities   exist; some of   these opportunities are
liscussed later in this section.

4ater Conservation and Reuse

\  tannery survey of  water needs will help to   reduce   the  volume  of
vastes  because water usage generally  exceeds  the  quantity needed.
Some methods  of water  conservation  are  listed  below:

     1.   Encourage employees to implement any  potential
         water  saving  practices.  Eliminate  the
         constantly  running  hoses observed in  (a few)


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          tanneries (one practice requiring employee
          participation) .

      2.   Examine tanning formulas to determine if floats
          can be reduced.   Use of hide processors
          and other specially designed vessels has
          permitted use of lower float volumes.

      3.   Limit or eliminate some washing and rinsing
          operations.

           a.   Use batch rinses,  or alternative ly, use
                the counter-current flow technique.

           b.   use preset  meters  or timers  to limit  total
                flow.

      4.   Use of wash waters and  rinses  for process  solution
          makeup.

      5.   Use of equipment such as  hide
          processors, pumpable drums  (rather  than  floor
          dumping),  float storage tanks,  and  other reuse
          equipment.

      6.   Recirculation of non-contact cooling  water,
          such as  for vacuum driers.

Tannery no. 397 has  undertaken  a  comprehensive  water  conservatic
program.    Through implementation of this program, total water use h
decreased by nearly 50 percent.  Installation of hide  processors  fc
washing the incoming hides has reduced water use in thif process hv -
  ^^   °fPr°CeSS Wat« in th
    savinasol °2sPr°CeSS Wat« in th* ^"9 operationa     achiev<
    savings  of  25  percent.   Installation  of  paddle  vats  and
recirculating flume arrangement following the un hair ing operation V
                          -
              ~~~     « -  s         -
tine  screen  for  solids  removal.   A  vegetable tanning recycle ar
reclaim system using  evaporators  has  reduced  water  uL  for  +M


In recent years, the hide  processor  (modified  concrete  mixer)   ha
proven to be an extremely effective means of reducing water use and a
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en  hide  processors  are  used  in the  beamhouse operation,  water use
xough deliming will be about  8.35 I/kg of  hide (1  gal/lb  of  hide).
nnery   444,  which  uses hide processors for  all operations from the
.w product through chrome tanning or  "blue" stage,  has  indicated that
.ter use is  from  12.5 to 16.7  I/kg of hide   (1.5 to 2.0  gal/lb  of
.de).30  Some  tanneries use hide processors in the retan,  color, and
.tliquor operations.

iere are also reports of water reuse  from   one  process  to  another.
.nnery   no.   24   uses  the  same water  for  washing following their
lodified pickle"  operation  and their  vegetable  tanning  operation.30
iere  are  also   some indications that  retan operations can use spent
.quors from  the vegetable tanning process.   Tannery no. 144 indicates
;e of bate wastewater for alum tanning  make-up water.30  Tannery  no.
J5  plans  to  recirculate  approximately   20,000  gallons  per day of
reatment plant final effluent  water  for use in the  delime wash  which
>llows   the   hair pulp process  and  for wash water  following the bate
rocess.30

le Institute for  Leather and Shoe Research  (TNO), of the Netherlands,
ctensively researched water reuse.   The water  consumption   in  upper
rather   tanneries including rinsing  processes appears to be 70 to 100
'kg hide and in  sole leather tanneries  50   to  60  I/kg  hide.31  The
:udy  indicated   that  80 to  90  percent of  effluent volume  comes from
Lnsing   before   and  after  the   different   wet  tannery operations.
irough   measurement  of the electrical  conductivity of  wash waters it
is found that the conductivity decreases very rapidly after  a  short
Line; after that,  the decrease  is small  in proportion to the amount of
iter used.   It appears, therefore, that either shortening the rinsing
Lme  substantially  or  replacing the  rinsing by washing will save a
insiderable  amount of water.

ible  18  presents  a comparison  of procedures  for continuous  rinsing
.id  batch  washing.   The   batch washing procedure reduces the water
Dnsumption   to   one-fifth   of  that   in  the  standard   procedure  (a
eduction of  80 percent).31   It was  shown that process time can be
Dnsiderably  reduced also  if the  hides are not too  dry.  Differences
.1   leather   quality were  very  small  except  for the  distinctly tighter
rain obtained with the new  procedure,,
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    Table  18.  Soaking of Wet  Salted  Prefleshed  Hides
                 With Continuous Rinsing and Batch Washing


 	Standard Procedure      	New Procedure	

 Rinse continuously 1/4-hour         Wash 1/4-hour with 250
                                     percent water at 25°C

 Drain-                              Stop for 1-1/2 hours

 Add 250 percent water at      wash  1/4-hour (same water).
 18 degrees C.

 Drum 5 min/hour for 7 hrs.         Drain.
 Drain.

 Add 250 percent water at 18°C.

 Rest overnight  (15 hours).	

 Total time—24  hours               Total time—2-1/2 hours.

 Water consumption: 12.5 I/kg       water consumption:
 	—	nj-de     	2.5 I/kg hide	

 Many tanneries  in  Australia have  recently  economized  in  the   use
 water,   particularly by eliminating waste  in washing and by  the use
 lower floats   However,  lessened   water use  tends   to   increase  t
 suspended solids and BOD concentrations in the  wastewater stre^?32

 German   literature  has  reported  that "previously about 75  percent
 resultaanS°Ual<,n   T^  ™S  US6d  f°r rinsing   orations   and   as
 result,  and   also   as  a  consequence of working with  long floats t
     and^nf ^v   ?**?  *?**** ™facturerwas  somewhere
 140  and  200  I/kg of salted hide.  When rinsing  is replaced by bat
 washing the amount of water can  be  reduced.   short  floats  in  t
 tannery  operations lead to reduction in process time and a faster a
 more uniform uptake of chemicals, without the danger of a loose grai
 I/kg h!de?"32he t0tal am°Unt °f Water use can be reduced to 35  ?o

 French  and  British  research  institutes  support the replacement <
 rinsing  by  batch  washing. 3 2  In  Great   Britain,   tanneries
 considering  the  reuse of  liquors either direSly or after bioLaic
Based on a total plant consumption basis, Perkowski indicated that  <
—  German tanneries water use was reduced from 200 I/kg of raw hie"
some
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processed to as low as 40 I/kg while employing various  reduction  and
reuse procedures. 33 Work was also done on the following to reduce the
quantity of pollutants entering the wastewater stream:

     1    Brushing off adhering salt  from  the  salted  hides  before
          soaking;

     3.   Removing lime sludge; the lime can be used in agriculture or
          can be burnt in a kiln to recover quicklime (a possible lime
          recovery scheme)«32

P.J. Van Vlimmeren, at the Institute for  Leather  and  Shoe  Research
(TNO)  in  Holland,  has investigated water recovery and reuse schemes
within tannery processes.  He reports that when unhairing is  possible
in  the  first or second soaking liquor (i.e., in a salt solution), 70
to  80  percent  of  the  organic  pollutants  and  nearly   all   the
preservation  salt  can  be  collected  in  about  5  I/kg of raw hide
processed.  "For example,  a  tannery  which  was  using  14.3  litres
water/kg  hide  in soaking to reduce the salt content of the hide to 2
percent could obtain the same salt content by washings with altogether
4.2 litres water, i.e., a reduction of about 70 percent."32

Water use reduction and the associated changes  in  pollutant  loading
were  reported  as  follows  for a U.S. tannery  (No. 431) studying the
effects of in-plant process changes:

          "Hide processors were installed and  the  traditional  hair-
          save  methods  of  leather  production  were  replaced  by a
          •straight  through1  hair-burn  process  in  which  soaking,
          unhairing,  bating,  pickling  and  tanning  is accomplished
          within  a  single  processing  unit.   Besides   eliminating
          numerous hide handling steps, this process change effected a
          50  percent  reduction  in beamhouse-tanyard effluent volume
          from an average 107 gallons per side to 54 gallons per side.
          While much of this water was eventually restored as  'sewer-
          flushes,'  an  overall 38 percent reduction in 1970 effluent
          volumes has been observed, primarily  due  to  an  intensive
          water  conservation  campaign.  Consistent with a 50 percent
          reduction in lime usage, the pH was lowered from 11.0 to 9.8
          with a corresponding 31 percent reduction in fixed suspended
          solids."34

Other tanneries reporting on their extensive and intensive  wastewater
reduction  program  indicated  that,  typically,  the first 50 percent
reduction was achieved primarily by educating all employees  on  water
conservation practices and management emphasis on constant use of such
practices.   Water  reuse  within specific processes in the tannery is
the  second  thrust  of  this  wastewater  reduction  program.   Reuse
technologies  tend  to  involve  simple, widely used equipment such as
cooling towers, filters, separators, decanters or holding tanks.   The
cost  of  purchase  and  installation  is rapidly recovered by reduced


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 water and chemicals use,  lower sewer  charges  or  less  obviously  by
 reduced loading of a tannery's own treatment system.
                                                              -V*
 A concomitant of water use reduction may be an increase in a pollutant
 concentration  in  pretreated  discharges  to municipal systems.   Most
 municipal  ordinances  regulating  discharges  to  a    sewer   specify
 concentration  limits.   A joint understanding of the actual municipal
 requirements at a specific sewer inlet and of the likely  consequences
 ot  a water reduction program in a tannery would be a vital first step
 to an informed decision by  both  a  municipality  and  a  tannery  on
 controlling   wastewater    volume,   pollutant  concentration,   and/or
 pollutant loading.

 Repair and Replacement of Faulty Equipment

 Industrial waste problems are often complicated or intensified  by  the
 fact  that  faulty   or obsolete  process equipment remains in  service
 without proper repair or  replacement.   Operating  personnel  also  can
 increase  waste  disposal  problems because large quantities  of usable
 materials often are lost  through  careless  or  accidental   spills  or
 through   excessive  drainage  of  liquids  from  hides   as  they  are
 transferred from one process  to another.   Emphasizing the   importance
 of eliminating these sources  of wastes  often  simplifies  waste disposal
 problems.

 Automatic Monitoring Devices

 No  waste  reduction  and  elimination  program can  be complete  without
 adequate   control   measures.    Automatic   monitoring   equipment    for
 detecting  abnormal  levels   of  selected  constituents  closely guards
 against   the   failure of  established  precautionary measures.    For
 example,  abnormal and accidental  concurrent discharges of concentrated
 highly    alkaline   lime-sulfide  unhairing liquors   and  highly   acid
 chromium  tanning or pickle  liquors  are  immediately  detectable  by  DH
 meters    and   alarms   installed  on  the   effluent  lines   from   these
 processes.  In addition to  indicating   loss  of  materials,   automatic
 sensing devices also  can  operate  recovery  equipment.

 Recovery and Reuse  of  Process Chemicals

 The  most  efficient  method  of  eliminating  pollutants from tannery
wastes and of reducing the volume of  effluent  is  through  reuse  of
water  and chemical agents and through recovery of materials which are
normally wasted.

Reuse or  reduction  of  process  solutions  or  recovery  of  process
chemicals  are demonstrated methods of waste constituent reduction.  A
detailed summary of methods available to reduce waste  constituents  bv
process adjustments is given by Williams-Wynn.as
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\  number  of  vegetable  tanneries  are  using recycle  systems  to reduce
^he amounts of  tan liquor discharged into  the  waste  streams.    The
jiritan  process  employs  such a technique by counter-current flow of
-annage in relation to the hides.  In most  cases,  some  blowdown  is
necessary  to  prevent the  build-up  of  contaminants  in the tanning
solution.  One  tannery recovers this blowdown tan liquor,  concentrates
Lt in a triple  effect evaporator and sells  the  concentrated  liquor.
Dther tanneries use this  blowdown liquor in retanning operations.

Reuse  or  recovery  of  chrome tan liquors also exists  but not to the
same extent as  vegetable  tanning.  Hauck36 has summarized   methods for
recovery and reuse of spent chrome  tanning  solutions.  During  World
rfar  II, the reuse of chrome tan liquor was common practice because of
the scarcity of chromium  salts.

Tannery no. 279 studied the reuse of chrome tanning solutions.   These
tests showed that the chrome liquors could be reused  for periods of up
to  six  weeks   without  reduction  of leather quality.30 The spent tan
Liquor in this  study was  settled and sludge was drawn off   the  bottom
of  the  holding  tank.   The  clarified  solution was  brought to the
required concentration with chromium salts, sulfuric  acid, and  sodium
chloride.   Because  of  the  sludge drawoff, this was  not a complete
recycle system; however,  a substantial  portion was recycled and only a
small amount wasted.

This same study also examined the  feasibility  of recycling  of  the
unhairing  solutions.  Tests  on recycling of the unhairing solutions
were performed  on three separate occasions.  The longest recycle  time
was   two  weeks.   The  study  concluded,  however,   that  since  the
concentration of waste material in  the  solution leveled  off  after  a
few  days, the  solution conceivably could be reused indefinitely.   The
spent liquor was drained  and settled in much the same manner  as  the
chrome  tan  liquor.  After removing the sludge from  the bottom of the
tank, 65 percent of the original volume remained.  About 50 percent of
the sulfhydrate and the lime needed for the next run  was available  in
that portion retained for reuse.  After two weeks of  use,  the solution
had no objectionable odor and the amount of ammonia coming off was not
considered substantial.

Tannery  no.  253,  a  shearling  tannery,  has been  able  to reuse its
chrome tan solution up to five times.30

The same tannery has reused its pickle  liquor up to five times.   This
is  accomplished  through  refortification  of  pickle  liquors by the
addition of chemicals prior to adding another load of hides.

Tannery no. 388 reports  reusing  retan  liquors.30  Tannery  no.   385
reports  reusing the finishing oils.30  Many tanneries report recycling
their pasting frame water, either wholly or partially.
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 Stream Segregation

 In-Plant Treatment.   Stream segregation is not an  in-plant  treatmen
 technology,   ^er.  se.   it  is,   in  reality,  a critical first step t
 implement most in-plant technologies  available to  tanneries.    It  i
 the  physical  separation  or  segregation  of  at least the two majo
 wastewater streams  in  a  tannery.   One  stream  originates  in  th
 beamhouse, is highly alkaline,  and contains a  substantial organic loa
 of  dissolved  and suspended hair. The other  stream originates in th
 tanyard,  is  acidic,  and has a chrome  content of measurable level.

 These two major and  substantially different wastewater  streams can  b
 most  effectively pretreated  as  separate streams rather than in
 combined  state.   These two major   streams  are  the  specific  proces
 waste  streams  which  respond  more completely and cost effectively t
 separate  treatment.                                                *

 Based upon information from tanneries no.  237  and 431,   EPA  develope
 proportionate  raw  waste  load   flows  and pollutant   loads  from th
 beamhouse,   and   from  the  tanning,   retanning,   and  wet   finishin
 operations.     The  values  for   the   various   wastewater  parameters
 including flow,  are  presented in  Table 19.

                                Table  19

        Proportioned  Flows  and Pollutant Loads  for Beamhouse and
                  Tanyard/Retan/Wet Finish Operations
Parameter
Flow
BOD5
COD
TSS
Oil and Grease
TKN
Ammonia
Chromium
Beamhouse
40X
65
56
69
49
46
0
0
Tanyard/Retan/Wet Finish
60%
35
44
31
51
54
100
100
The isolation of the specific process waste streams or the segregatioi
of the two major streams can be accomplished by a variety of
means such as the following:
                                 132

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     1.   Pump-out  mechanism   on  the   drum,  wheel,  vat,  or  other
         processing  equipment connected   to   a  specific holding  or
         treatment tank or vessel by piping;

     2.   Collection of wastewater discharged from a   hide  processing
         vessel   directly  into  a  holding  or  treatment   tank  or
         container;

     3.   Separate below-grade  sewers;

     4.   separate above-grade  sewers;  and

     5.   Flow direction   control  diverters in grate- cove red  floor
         troughs.

Control  of  Specific Waste  Constituents

     Reduction.  Lime used in unhairing liquors  is responsible for the
alkalinity  of the final effluent.   Insoluble calcium compounds simply
add to the sludge quantity.   Though the pH of the mixed  effluent  has
to be sufficiently high to precipitate chromium salts, it is desirable
bo  reduce  the  amount  of  lime  to  a  minimum.   Experiments at the
Institute TNO by P.J.  Van Vlimmeren "have shown that an  amount  of  U
percent  hydra ted  lime  (on  salted  weight)  is an optimum level with
regard to the quality of the leather.1131

"Because lime has a limited solubility, it is generally regarded as  a
•safe1 alkali for use in unhairing.  Consequently,  tanners are tempted
to use a considerable excess of this material — far more than is needed
to  satisfy  the  alkali-binding  capacity of the skin collagen and to
keep the liquor saturated with lime."  So reports D. A.   Williams-Wynn
of  the  Leather  Industries  Research  Institute   (South Africa) in a
report concerning various operable  concentrations  of  lime  liquors.
The  study points out that, "the disposal of this excess of lime, most
of it undissolved but not easily settled, especially in  the  presence
of  soluble  protein,  is  a  problem  with  which  tanners constantly
grapple, yet they persist in using a large excess."35

Their "experiments have shown that  the  amount  of  lime  needed  for
effective  unhairing is less than is required to saturate the protein,
so there is certainly no justification for any undissolved lime to  ce
present in beamhouse liquors."35

Table  20 lists the values for insoluble calcium hydroxide in effluent
from 6-day hair-saving pit liming processes in which  the  lime  offer
was  progressively  reduced.   The  table  is reproduced from William-
Wynn's published study.35
                                 133

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                  Table 20.  Analysis of Lime  Liquors
Lime Offered
4 percent
3 percent
2 percent
1 percent
Insoluble Ca(OH)_2
in Lime Liquors
0.43 percent
0.22 percent
0.01 percent
KT-i 1
Lime Unused
53. 5 percent
36. 6 percent
3. 5 percent
 ~ ^"C"U	.  Nil	Nil

 "Unhairing was effective even at the  lowest  level
                                                        of  the   lime
          amount  under  two  percent   seems  to  be  the
                   anao«
                   and  0.4  percent.   The  values  are means of fnnr-
      determinations averaged over  the  four sulfide con^ntrat ionf. "3 *

      "In a hair-burning,  drum-unhairing process in which  the  sulfide
      off^* W?S  mu°h  
-------
The  following summary is  quoted  from  Money  and  Adminis1  research:

     "It   has  been   shown  that  lime-sulphide unhairing  liquors  can  be
     recycled more than 20   times,  perhaps indefinitely.    The  only
     treatments necessary before re-use are temperature  adjustment and
     replenishment  with  lime,   sulphide  and   water,   preferably  as
     washings from the previous  unhairing.   For 20  cycles  the average
     consumptions based  on  greenhide  weight  were 1.5% lime,  2.2%
     sodium sulphide and  40-55%  water;  the  higher water  usage occurred
     when solids were removed before  each use,  a procedure  which  has
     advantages.  Salted  hides can  be unhaired satisfactorily  in re-
     used liquors if they first  have  an adequate soak to reduce  their
     salt  content.    Recycling  of  lime liquors has no apparent  effect
     on leather quality or   yield  even  though, when   compared  with
     conventional unhairing, it  results in  a decrease in hide swelling
     and  an  uptake  of  proteins of  their  degradation products.  This
     method could be developed as a no-effluent system of  unhairing  if
     liquors can be  cycled  indefinitely or, after a certain number  of
     cycles,  can be  utilized   as  a source  of protein.   Even  if the
     liquors are discharged after 20  uses there can be overall  a  20-
     fold  reduction  in  effluent   sulphide,   seven-fold  reduction  in
     effluent lime and protein,  and a five-fold reduction  (80 percent)
     in the amount of water used.  If wash  liquors  from  the  previous
     unhairings  are  used   to replenish the float, as  is  recommended,
     the fresh-water consumption could also  be  reduced  20-fold   (95
     percent)."37

Obviously  it  is simpler to leave  the solids  in the liquor.  However,
if they are removed  after each use    (or  several uses)  there  is  no
problem  with  fat  accumulation, the protein  recovery  is  greater, and
the hides are cleaner after unhairing.  Vibrating and rotating screens
and other systems for removing the  solids from the   liquor  are  being
investigated.  It is an advantage to be able to remove  the hair debris
and fats without removing all the insoluble lime.   The   present  work
has  shown  that only a small proportion of the lime liquor protein  is
lost as volatile products,  but substantial  amounts  of the   protein  or
its degradation products are taken  up and retained  by the  hide.   It  is
estimated that a hide unhaired in a recycled liquor would  contain more
protein,  approximately  1   percent  of the green hide  weight, than  it
would if unhaired in a fresh lime liquor.  This extra protein could  be
beneficial by adding substance to the leather,  and  it could affect the
feel of the resultant leather;  but  in  the  matched-side  trials  no
differences have been detected in the final leather.

Most  existing  beamhouses   would have to be modified for  recycling  of
lime liquors, and the facilities necessary will be   similar  to  those
for  recycling  chrome  liquors.   Rapid and effective drainage of the
liquor can be achieved by using a drum with a perforated false  bottom
covering  a  drainage  valve,  or  a  hide  processor or cement mixer.
Provision of a storage tank capable of holding  the  daily  output  of
lime liquors plus washings  would be preferable; but it may be possible


                                 135

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 to  pump  liquor  directly  from one drum to another.   A pit unhaird
 system would be ideally  suited  to  recycling,   although  floats  a
 amounts of reagent would  differ from those given for  drum liming.

 A  sulfide reuse system has been installed and used by tannery no.  2
 (subcategory one  -  Hair  Pulp/Chrome  Tan/Retan-Wet   Finish).    Th
 system  has achieved a  reduction in sulfide-containing wastewater fr
 27,000 gpd to 10,000 gpd.

 This reuse  scheme  was  developed  by  an  Italian engineering   fi
 (Idronova)   and  operates   with  sedimentation and  filtering equipme
 used by the European wine  industry.   The system  operates as follows:

      1.    The unhairing float  from the hide processors is pumped  to
           enclosed holding tank at 12 gpm.   From there it is pumped
           a rate of  20  gpm  to  a  hydrodynamic  sedimentator   whi
           facilitates  solids   settling  and  filtration  of the  flo
           during gravity  flow.   Pumps  provide  circulation  and   si
           reduction to  reduce  large solids  to about 1/4  inch size.

      2.    Solids are settled out using gravity and  centrifugal   for
           with  the solids  being drawn out  the bottom  of the unit  in
           a solids container for  disposal.    oil,  grease  and   oth
           floating material are skimmed off the  top of the solids  bo

      3.    The supernatant  sulfide liquor flows close to  the top of  t
           separation chamber, where  it is  drawn   off.    The  reclaim
           liquors  flow by gravity to two large storage tanks.   Fr
           these  tanks the  reclaimed  liquors are   pumped   back to   t
           hide   processor.   Some sludge   build-up occurs   in  the
           storage  tanks,   but   it  is   subsequently   discharged    a
           disposed of as solid  waste.

      4.    The  tanks  are closed  and vented outside the  the  building
           prevent  any  build-up  of   sulfide  in  the   building.   1
           storage tanks are  also provided with mixers.

Enzyme Unhairinq  for  Hair-Save   Operations.   Prerequisites  for   a
hair-saving  method  are:  it must  unhair easily and mechanically, wi
removal of  fine hair  (if  possible  without   reliming);   it  must
economical,  not   time-consuming;  it must be  suited to mechanized  a
automated production processes;  and it must give  good  leather qualit
Hair-saving processes require more labor than  hair-burn processes, a
tanners will not  incur additional  costs unless there is a profit  fr
the  proceeds  of  the hair and a cost savings  in wastewater treatmen
Present trends in  the industry are  definitely  toward  the  hair-bu
process.

Frendrup and Larsson** made a detailed study of the effects of vario
depilatory  methods  on  the  characteristics  of the residual waste
They  found  that  when  hair  was  loosened  chemically  and  remov


                                 136

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mechanically,  the  total  nitrogen  content  of  the unhairing wastes
averaged 1.2 g/1.  When the hair was destroyed completely by  chemical
means  (hair-pulping  or  burning),  the total nitrogen content ranged
from 5 to 7 g/1.  In addition,  an  appreciable  reduction  in  oxygen
demand,  and  in  quantities  of sulfides and sludge was observed with
hair-saving methods.  Hair containment and housekeeping practices  are
significant influences on these results.

Enzyme  unhairing  is  one  of  the  hair-saving  methods known at the
present time.  Based on a considerable  amount  of  work  by  the  TNO
Institute,  this  method  reportedly could be developed for use in the
production of sole leather, but for upper leather some difficulties in
connection with the feel of the leather still  must  be  overcome.   A
combination  of the Liritan vegetable-tan process and enzyme unhairing
 (for  sole  leather)  was  also  investigated  at  TNO.3*  The  latter
combination  of  the  two  developments reduced pollution by vegetable
tannage to only 10 percent of that from traditional methods, according
to TNO.

Sulfide Removal.  In situ sulfide oxidation in the drum or paddle with
the hides  has  been  investigated  and  is  in  use.   TNO  Institute
investigated3i  this  method of oxidizing sulfides in the lime liquors
during and after the liming process.  It was  found  that  a  vigorous
movement  of  the liquor and a free air supply are very important.  In
the alkaline medium the manganese  catalyst  converts  into  insoluble
manganous  hydroxide.   Flotation of the hydroxide by hair remnants or
foam must be prevented to retain the  catalytic  activity.   When  the
oxidation of sulfides is combined with the liming operation the latter
 is  started  in  the usual way, either in a paddle or in a drum. After
complete removal of the hair, a small  amount  of  manganous  sulfate,
e.g.,  200   g/cubic  meter   (m3), is added and paddling or drumming is
continued for some additional time.  Using hair-burn liming procedures
and the lowest  sulfide concentrations necessary for complete unhairing
and the production of good quality leather, over  95  percent  of  the
residual  sulfides  could  be removed by oxidation within three hours.
 This additional  drumming had  little  effect  on  the  appearance  and
physical  properties of the leather produced  in this way.  Tannery No.
 245 is using this method of in  situ  sulfide  oxidation  as  standard
practice.

 The  TNO  technique of  in situ sulfide oxidation in combination with  a
 sulfide liquor   reuse   system  reduced  the   sulfide  content  of  the
 wastewater  discharged to POTW from  118 mg/1 to about 2 mg/1 concurrent
 with a reduction in wastewater volume.

 Chrome Reduction.  Tanyard wastewater is  generally acidic and, because
 of  the chrome  content,  is toxic  to some  organisms.  The acidic nature
 of the waste stream can be neutralized  by mixing  with  the  beamhouse
 wastes  that are   alkaline   or   by pH  adjustment with chemicals.  The
 chrome  content  can  be  reduced  by   using  one  of  a   number   of
 technologies.    One technique  is  to increase the uptake of chrome by


                                  137

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 the leather in tanning.   A second is to reuse chrome liquors,   as  is,
 in some part of the beamhouse,  tanyard, or retan process without first
 recovering   the  chrome  from   the  solution.    A  third  way  is  to
 precipitate the chrome with an  alkaline chemical, producing  a  chrome
 sludge  either  for  disposal  or  for  chrome  recovery.   The  alkaline
 chemical source can be beamhouse waters,  fresh  lime,  or bases  such  as
 caustic soda or soda ash.

 Aside from their application as methods of reducing the chrome content
 in tannery wastewater some of these methods have been used in  the past
 as  chrome conservation  methods.   During World  War II,  chrome  supplies
 were cut off and tanners were able  to  reduce   their  chrome   use  20
 percent.39  under  current  conditions of increasing  chrome prices and
 reduced  imports,  an economic  incentive  exists  for  tanneries  to
 introduce these methods  of chrome conservation,  which will improve the
 wastewater  quality  as  well.   In fact, several  tanneries have already
 started chrome recovery  and reuse programs.

 Increasing the uptake of chrome is an  effective  method   of   reducing
 chrome  in  the wastewater and  conserving chrome.   Chrome fixation can
 be increased by increasing the  chrome  concentration,   increasing  the
 temperature,   adjusting  the concentration  of   neutral   salts to the
 minimum required to prevent swelling  of   the hides,   increasing  the
 basicity  of  the  chrome   waste  slightly,  and adjusting  the pH of the
 tanning liquor during the  tanning process.   Some of these methods  may
 affect  the  quality of the leather.*«  After World War  II,  tanners went
 back to the  older methods.   The efficiency of chrome  use  is now  about
 70 percent.3*

 Reuse  of chrome  liquors   without first removing the  chrome  has been
 extensively  studied recently and  is practiced in some tanneries.   From
 the  literature  it appears  that  the most  common   technique  in  chrome
 liquor  reuse  is to fortify the liquor  with  acid and salts and use the
 forfifled liquor in the  pickling  process.  The chrome introduced   into
 the  pickling liquor gives  a pretannage.

 Scroggie   and   others  in Australia did  a  series  of  studies on  reuse of
 spent chrome tanning  liquors for  pickling.   In the  fourth  part«o  of
 the   studies  the spent  chrome  liquor was  used to make up the  pickling
 acid  added to the hides right after the bate.  The hides were  obtained
 from  five different Australian tanneries.  Scroggie obtained more  than
 5 percent uptake of chrome as Cr2o3  on  a  dry  weight  basis.    This
 chrome  was  distributed  in a normal fashion throughout the hide.  He
 reused the chrome 12 times over the course of several months and noted
 that the concentration of neutral  salts reached steady state in  about
 J  to  4 cycles.  He recommended that "the liquors can apparently then
 be  used   indefinitely    (with   occasional   screening,   etc.,   as
 necessary). "*o                                         ^'    uv" '   "*

In further studies**, Scroggie ran actual plant tests at an Australian
tannery  which used hide  processors for the tanning process.  He found


                                  138

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that a savings of about  25  percent  could  be  realized  on  tanning
reagents  in  Australian  tanneries.   A  second  run of 18 successive
cycles over the course of several months again revealed  that  neutral
salt  concentration  reached  steady state after three or four cycles.
Scroggie also thought that hide processors were better than drums  for
this  sort of recycle process because the lime and bate liquors can be
readily removed as needed minimizing volume build-up and problems with
pH.  It is also possible to pump spent chrome  liquor  out  below  the
level of the oil layer and to pump the sludge out of the bottom of the
hide  processors  to  get  a  clean recycle stream.  It is possible to
remove  about  95  percent  of  the  spent  chrome  liquor  from   the
processors.   There  is  about  20 percent savings of chrome, complete
savings of neutral  salts,  and  no  increase  in  dissolved  protein.
Scroggie  also  indicates  it is possible to modify a tanning drum for
reuse to get similar results.  Scroggie further reported that:

     "Throughout the entire process the  're-cycled'  leather  was  at
     least  comparable  with  corresponding  leather  from  the normal
     production.  On removal from chrome-tanning, the  leather  showed
     no difference in general appearance, grain quality, or  'feel1 and
     there  was  no  grain  'draw1,  chrome  'blotching'  or veininess
     apparent;  random  cross-sections  showed   a   complete   chrome
     penetration  in  all cases.  These observations were confirmed by
     the tannery personnel who carried out a  complete  assessment  of
     the finished leather.  They reported that there was no  difference
     in  the  subjective  properties  of  the  're-cycled' leather when
     compared  with  normal  production  leather  of  the  same  type.
     Neither  was  any  difference  detected  between   're-cycled' and
     control sides in Lastometer  load  or  distension,  or  in  Cr2<33
     content or ash weight of the finished leather."41

And he  concluded that:

      "A method  is now available for the re-cycling of chrome liquors
     which  can  be   fitted  into   current  production  schedules    in
      tanneries  and   which  has  been   shown   to   produce  leather   of
      comparable   quality   to   that   produced     by     conventional
      processing."4l

 In  the  sixth part of  his  studies42,  Scroggie  reported on a series  of
 full-scale  tannery tests of chrome   recycling.    He stated   that  the
 common   chrome   uptake  of  70 to  80  percent  is  a consequence  of the law
 of mass action—reaction rate  depends  on  chrome  concentration—rather
 than any  inactivation of  the chrome complexes thereby  requiring  an
 intermediate  reactivation  before reuse.    Thus,   direct reuse   is   an
 effective  technique.    He   found   that  the   solid  commercial  chrome
 preparations  were  better than  the  liquid  forms  because   there was   no
 accumulation  of  excess  chrome  liquor to be disposed.

 Hide  processors  have the  best  drainage  characteristics  for recycling
 chrome, but they should be  lined to prevent corrosion.   Two  collection


                                  139

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 tanks for the chrome liquor  are  necessary.    Lime-sulfide  unhairinq
 solution recycling is desirable but not necessary for effective chrome
 recycling.   in  several  of  these  tests  the quality of the leather
 decreased.  This was traced to a slight acidic swelling of  the  hide
 Scroggie  lists several advantages of chrome  reuse.   The first is that
 the possibility of shock loading on the secondary biological system is
 reduced.  The second is that the required amounts of  sodium  chloride
 and  sodium  sulfate are reduced.  The third  is that there is a saving
 of 20 to 25  percent  of  the  associated  cost  for  the  process  in
 Australian  tanneries.   The other three advantages of chrome recycling
 which he cites are:                                                j-j-"y

      "(iv)  With proper  control,  leather of at least  comparable quality
      to conventionally  tanned leather can be  produced while there  are
      indications   that  leather  quality  can  be  improved  in  some
      respects.

      " (v)  Recycling  is  considered to be superior  to  the  alternative
      method   practiced   in   some  overseas  countries   of  chromium
      precipitation and  recovery  as it is more convenient  to use and is
      less  costly.  It is  also considered to provide   a more  complete
      solution to the problem than that provided by attempts to improve
      the  uptake  of chromium,   for  example,   by the use of  very low
      floats or  more  highly  reactive chromium  reagents.

      "(vi)  The   possibilities  for  economic   utilization  of   tannery
      sludges  are  extended  by   the  exclusion  of   chromium  which is
      precipitated  in such sludges by the common method of   mixing  of
      all tannery processing effluents for treatment."

Ward,   Slabbert and Shuttleworth have  described tests of  chrome  reuse
and recovery  in South Africa.*3  The  sulfate reached  steady  state  after
four  cycles.  Chrome analyses  and other  precautions   are  recommended.
France**  studied  the  use   of   organic  acids  for  pickling and  later
studied  recycling  of spent  chrome/organic  acid  liquor to the   pickling
process.    He   tested his method  at  several tanneries and found little
difference  in the  properties  of the  leather produced by his method  and
conventional  processes.   He  obtained   faster  tanning  and   better
exhaustion  with   his  method.    He tried recycling of the  liquors  for
even greater efficiency and possible  economic advantages.  He  advises
against  reusing the wring liquor because of its fat content.  He also
advises  pumping the  spent chrome liquor  about 2  feet  below  the  oil

r^ J   /^T ^* SlUdIe leVel-  He found that less chrome c°uld be
charged and all of it used.  About half  as much time was required  for
S^h Fr?CeS?i af  H?6  convention<*l Pickle plus tan processes require.
With a low  float, the pickle may even be  eliminated  in  some  cases
His  process  requires no added salts because the low float results in
more concentrated liquors.  About 10 to  11  percent  of  the  recycle"
stream  consists  of  soluble  salts at steady state.  The cost of the
organic acids, a mixture of formic and acetic acids,   is  higher  than
sulfuric  acid.   The  same amounts are used,  but faster processing is
                                 140

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possible and savings in other chemicals can  cut  overall  costs.   He
mentions  that  this  process  is  already in use but does not mention
where.  The additional equipment required  for  this  process  is  one
tank,  one  pump,  and  some  piping; investment could be low for this
reason.

Pierce and Thorstensen have published an account of the  chrome  reuse
at  tannery no. 245. *5  Hide processors are used at this tannery.  The
spent chrome liquors are collected in a tank large enough to hold  six
tannages.  Oil and grease are skimmed to prevent darkening of the blue
stock,  and the liquor is used for pickle make-up.  Sulfates and other
salts build up at first but eventually level off.  There is more spent
chrome liquor available than is required for pickle.  When the  excess
completely  fills the tank it is precipitated with soda ash and sodium
hydroxide for reuse.  This does not decrease the amount of chrome used
in the tanning process, but with the reuse of chrome in the  pickling,
there  is  increased  uptake  without  additional chrome being bought.
Pierce and Thorstensen note that the system saves money and  that  the
chrome  released  to the sewer typically is 1.6 mg/1 (as Cr) , based on
an effluent flow of 600,000 gallons per day.

Tannery no. 233 is reusing chrome.  The chrome  liquor  is  collected.
They  skim  grease and remove the suspended solids.  Then they use the
clear chrome liquor without grease or fibers  as  a  pretan.   If  the
grease  is  not removed there can be a color problem.  Previously they
precipitated chrome with beamhouse  waste  from  a  pigskin  unhairing
operation or sold spent chrome.  A concentration of 2 mg/1 of chromium
has been achieved in the total discharge to the municipal sewer.

Precipitation  of  chrome  for recovery was practiced in World War II.
Hauck has published a paper outlining the  methods  in  use  then  and
known  now.  Precipitation may be accomplished by beamhouse wastes, by
fresh lime, or by bases whose sulfates are soluble,  such  as  caustic
soda  or  soda  ash.36  The  chrome  precipitate may be disposed of or
recovered for use in the process.  Hauck recommends using a base whose
sulfate is soluble for the precipitation.  In  this  case  the  chrome
precipitate  may  be washed to remove the sulfate before the chrome is
recovered.  This prevents build-up of salts.  He finds that fresh lime
is not as good because the calcium sulfate whch is  formed  cannot  be
washed out.  He recommends using beamhouse waste for the precipitation
only  if  the  chrome  is to be disposed of instead of recovered.  For
reuse the chrome precipitate is  redissolved  in  sulfuric  acid,  the
chrome  solution is analyzed, the basicity and salt concentrations are
adjusted and it is ready for reuse.

An article in Leather and Shoes describes chrome precipitation with  a
proprietary   buffer   mix.46  The  supernatant  chrome  concentration
reportedly can be lowered to about 0.1 ppm average  (range 0.06 to  0.5
ppm) with this product.
                                  141

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 A  new  process for chrome precipitation uses sulfides.  This process
 called "Sulfex", avoids the  problem  of  the  possible  evolution  of
 hydrogen  sulfide  by  using only a small amount of soluble sulfide in
 equilibrium with an excess amount of nearly  insoluble  iron  sulfide
 The  leftover iron sulfide is filtered out with the precipitate.   This
 process appears to be useful for  removing  small  amounts  of  chrome
 remaining  in  the  wastewater  after  the bulk of the chrome has been
 precipitated.   It  does  not  appear  to   be   suitable   for   bulk
 precipitation of chrome.** *e

 A  full-scale  tannery  test  of  chrome  precipitation  and reuse was
 conducted at tannery no. 431.34 During this  test  only  part  of  the
 chrome  liquor  was  collected  for  precipitation.   The entire liquid
 contents of the hide processors used for chrome tanning were collected
 in a tank at the end of the  tanning  process.    None  of  the  chrome
 liquor from retan or chrome-containing liquors  from operations such as
 wringing  was collected.  About two-thirds of the chrome was collected
 and about one-third was not.    The  collecting   tank  could  hold  the
 contents  of  two hide processors at once.  Alkali and polyelectrolvte
 were added,   soda ash and lime were the alkalis  tested  to  determine
 which was the more cost-effective.   The precipitated chrome sludge was
 thickened to about half its original volume,  then further thickened on
 a  vacuum filter.   The chrome sludge cake was conveyed to another tank
 and dissolved in sulfuric acid.   A  cyclone  separated  the  insoluble
 calcium  sulfate from the dissolved chrome and  the chrome solution was
 then stored  for reuse.   This  precipitation process  recovered  between
 98.0  and  99.9  percent of the  chrome from the liquor.   When lime was
 used to precipitate the chrome,  some of the chrome  ended  up  in  the
 calcium sulfate sludge which  was to be landfilled.   In this case  about
 66   percent   of the chrome  was recovered in usable form.   The effluent
 trom the  chrome recovery system  contained  about   2   mg/1  of  chrome
 Because only part  of the chrome  was treated,  however,  the reduction of
 ™  o   f ?v   c^omiim ln the effluent was 37 to  40  percent.   Collecting
 more  of the  chrome  would result  in  a greater  reduction  of   the   total
 chromium   even   if   the  treatment   efficiency  was not as high.   EPA's
 pretreatment  standards  and  effluent   limitations  assume   a   chromium
 r^?rVTtem  
-------
noted  by  data from tannery no. 431, over 98 percent of this chromium
is assumed by EPA to be recoverable.

Ammonia Nitrogen Reduction.  The nitrogen loadings in the raw waste of
a hair-burn process have been reported as follows:

     1.   The average TKN loading  for  subcategory  one  (hair  pulp,
          chrome tan, retan-wet finish) is 11.7 kg/kkg and the average
          ammonia nitrogen loading is 5.5 kg/kkg hide.49

     2.   An EPA sponsored tannery study reports 15.7 kg/kkg  of  hide
          of  TKN, and the 4.6 kg/kkg of hide for ammonia nitrogen, in
          which the bating operation is totally  responsible  for  the
          latter.34

These  loadings  indicate  that the elimination of nitrogen-containing
deliming chemicals  during  the  bating  process  would  significantly
reduce the ammonia nitrogen and TKN in the effluent.

Koopman  of  TNO has analyzed residual liquors for nitrogen in a paper
on deliming with magnesium sulfate.5° The standard procedure  (deliming
with 3 to 3.5 percent ammonium  sulfate)  produces  a  total  nitrogen
content  of  7  kg/kkg  of  hides; in comparison the test procedure (7
percent magnesium sulfate) results in a total nitrogen content of 0.62
kg/kkg of hides.  Koopman also  indicates  a  total  addition  of  7.4
kg/kkg of ammonia sulfate, which is 0.4 kg more than the residual.  He
attributes this loss to some of the nitrogen from the ammonium sulfate
escaping in the form of NH_3 gas during deliming.

Koopman  elaborates  in  his  paper50 on alternative deliming media as
follows:

     "The purpose o." deliming is partially or completely to neutralize
     the bases present  in  the  hide  without  giving  rise  to  acid
     swelling.   In  this  process,  the  lime  must also be partially
     removed in order to prevent the formation of spots.

     "The deliming media in use in leather preparation may be  divided
     into four groups:  namely, ammonium salts, strong deliming acids,
     weak deliming acids, and deliming with magnesium sulfate.

     "1.  Ammonium Salts

     "In the deliming of  cowhides,  use  is  made  preponderantly  of
     ammonium  sulfate  and ammonium chloride, alone or in combination
     with acid.  The  combined  action  of  ammonium  salt  plus  acid
     depends  on the principle that the ammonia, which the lime in the
     hide frees from the ammonium salt,  is  again  converted  to  the
     ammonium  salt  by  the  reaction  with the added acid.  Ammonium
     salts of organic acids are used as well, frequently with addition
     of organic acids with the same acid residue as from the  ammonium


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 salt.   Thus buffer solutions are created,  which have the property
 that  they can be used to neutralize reasonable quantities of  lye
 without danger of excessive pH,  which might  give  rise   to acid
 swelling.

 "The  use   of  ammonium salts in the deliming of cowhides confers
 the following advantages:

      1.    Deliming can be accomplished rapidly.

      2.    No acid swelling can occur during deliming.

      3.    Alkali  swelling is largely eliminated.

      4.    The most frequently used  ammonium  salts   (sulfate   and
           chloride)  are inexpensive.

 "2.   Strong Deliming Acids

 "In addition  to  strong   inorganic  acids like hydrochloric  and
 sulfuric acid,  a  number of organic  acids must  be included in this
 category,  such as formic acid,   acetic acid,   lactic  acid,   and
 aromatic    sulfonic   acid.    Strong  deliming   acids,   such  as
 hydrochloric and  sulfuric,  are cheap.   They are  in  general  use as
 preliminary deliming agents,  achieving a   superficial   deliming.
 Because  of  the   fact that with these strong  acids  the  pH  during
 the deliming can  fall  very rapidly,  there  is   always  the  danger
 that acid  swelling  will  set in the  delimed  outer  layers  of  the
 hide before the acid has had  time to  penetrate  deeper   into   the
 hide and delime the deeper  layers.  The somewhat  milder lactic  and
 formic  acids can be safely used, adding them  in  installments  and
 checking the pH of  the deliming  liquor  and  the hide.  Because  of
 the  slow course of  the deliming, these acids are  used principally
 in   the  deliming  of  thin  skins  (goat, sheep, calf), and not  for
 cowhide.   Disadvantages associated with the use of organic  acids
 are  their   high  price,  together  with the resulting higher COD
 content of  the wastewater.

 11    Weak Deliming Acids

 "These do not directly displace  the  lime  bound  to  the  hide.
 After  neutralization  of  the  lime that is still present in the
 capillaries, the balance between chemically bound and  free  lime
 is  shifted,  the  free  lime  is  neutralized,  and so on.  This
 process  takes  place  very  slowly,  so  that  these  acids  can
 penetrate   into  the  interior  of  the  hide and provide uniform
deliming.   The most important agents  of  this  group  are  boric
acid,  and  sodium  bisulfite.   Boric acid yields leather with a
handsome grain, and is partly on that account regarded as one  of
the  best  deliming  agents.   Its  relatively high price and the
slowness of the deliming process  will stand in  the  way  of  its


                            144

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general  adoption  in the manufacture of cowhide.  Because of the
low acidity of boric acid, a substantial excess  is  required  in
order  to  obtain  complete  neutralization  of  phenol phthalein.
Sodium bisulfite is more frequently used as a deliming agent than
boric acid.  Commercially, it is available  mostly  in  anhydrous
form  as  sodium  metabisulfite,  Na2S2O5f  in  aqueous  solution
yielding the weak acid bisulfite NaHSO3.  During deliming, sodium
bisulfite is converted to calcium sulfite, which  is  not  easily
soluble in water, but the solubility can be increased by addition
to  the  deliming  liquor  of an excess of sodium bisulfite, thus
avoiding possible spotting.   Deliming  with  bisulfite  has  the
disadvantage  that in an acid medium the rather aggressive sulfur
dioxide can escape.50

"4.  Deliming with Magnesium Sulfate

"The fact that ammonium sulfate  and  chloride  give  very  rapid
deliming  of cowhide led Koopman and the other researchers to the
idea that this property might  also  be  possessed  by  magnesium
salts,  in  this  case the sulfate  (epsom salt) and the chloride.
The OH- ions from the pelt are bound in a similar manner  without
danger of acid swelling according to the following equation:

     Mg+2 + 20H- = Mg(OH)2

"The  chemical  reactions  for deliming with ammonium sulfate and
hydrochloric acid are:
     (NH4_)2SO4 + Ca(OH)2 = CaSOU. +

     2NH40H + HC1 = 2NH4C1 + 2E20

and for deliming with magnesium sulfate and hydrochloric acid:

     MgS04 * Ca(OH)2 = CaS04 + Mg (OH) 2

     Mg(OH)2 + 2HC1 = MgCl2 + 2H20

"It is apparent that in addition to the precipitation of CaSOj* in
the hide, there is now also a precipitation of  Mg(OH)2.   Alkali
swelling   is   largely  obviated,  the  Mg (OH) 2  precipitate  is
converted into a soluble  magnesium  salt.   Apparently  all  the
Mg(OH)2  still  present  in  the hide after deliming is converted
back to  a  soluble  magnesium  salt  during  the  pickling.   An
incidental  advantage  of  magnesium sulfate and chloride is that
they are two very cheap products.

"When deliming was carried out with magnesium  salts  plus  acid,
instead of ammonium sulfate plus acid, the researchers found:
                            1U5

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          1.   The visual characteristics  of  the  leather  were  not
               adversely affected.

          2.   The  most  important  physical   characteristics   were
               affected not at all or very slightly.

          3.    The  nitrogen   (TKN)  content  of  the  wastewater was
               significantly reduced.

          4.   The total processing time was not affected.

     "In addition, with  the  same  final  pH  after  chrome  tanning,
     followed  by  the same processing methods, the ash content of the
     leather in both cases would be equal."

Koopman states that commercial  deliming  products  can  be  used  for
deliming light leathers (thin hides); however, for deliming of thicker
leathers,   the  producers  recommend  only  the  products  containing
nitrogen compounds in the form of ammonia or amine.  Koopman describes
some of the factors or conditions which determine the required  amount
of a particular deliming agent:

     1.   The alkalinity of the hide,  which  is  connected  with  the
          method of liming;

     2.   The degree of deliming desired;

     3.   The course of the rinsing processes  after  the  liming  and
          preceding the deliming;

     U.   The thickness of the hide;

     5.   The time at which mechanical operations,  such  as  fleshing
          and  splitting,   are  performed,  with or without removal of
          lime adhering to the flesh side;

     6.   The desired deliming time.

Koopman concludes his research with the following remarks:

     "It has been found that in the  deliming  of  leather,  magnesium
     sulfate  shows  definite  promise  as  a replacement for ammonium
     sulfate.   Magnesium sulfate does not have a deleterious effect on
     the  quality  of  the   leather,    either   as   regards   visual
     characteristics  or as regards the principal strength and stretch
     characteristics.    Like  ammonium  sulfate,    magnesium   sulfate
     permits  complete  and  rapid deliming and acid swelling does not
     occur during the deliming.

     "Magnesium sulfate (Epsom salts)  is a cheap  deliming  agent;   as
     compared  with ammonium sulfate, the quality of the  effluent water


                                 146

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     is  distinctly  improved by its use.  The replacement of ammonium
     sulfate by magnesium sulfate in  deliming  can,  under  specified
     conditions,  lead  to  a  definite  reduction  in  the  estimated
     purification costs.

     "Tests on a semi-industrial scale using magnesium sulfate as  the
     deliming  agent  have  given, in all respects, favorable results.
     It would be a logical continuation to now increase the scale, and
     conduct  one  or  more  practical  industrial-scale  tests.    In
     addition  to  magnesium  sulfate,  the use of magnesium chloride,
     which is also cheap, might merit consideration."50

This information  suggests  that  deliming  with  epsom  salts  should
realize  a  67  percent  reduction in the ammonia content of the total
tannery effluent.  This percent reduction was based  upon  engineering
analysis  of  data  from  plant  no.  431  (Table 19)  on the amount of
aqueous ammonia which would be removed from  the  segregated  tanning,
retanning,  wet  finishing waste stream by complete removal of ammonia
from deliming.  Since ammonia is also measured as  TKN,  a  concurrent
reduction of TKN is achieved.

Summary of Industry Efforts to Implement In-Piant Controls

Table  21  lists  some  feasible  in-plant  process change methods and
indicates the number of tanneries which have  considered  and  decided
either  positively  or negatively to implement these in-plant changes.
Sulfide substitution and elimination of bating were widely  considered
but  the tanners found no solution which, in their experience, did not
interfere  with  leather  quality.   Fourteen  tanners  considered   a
substitute  for  ammonium  sulfate  and one tannery (no. 397)  has used
magnesium  sulfate  in  deliming  with  a  considerable  reduction  in
nitrogen waste load.

As  indicated  in  the table, opinion is almost equally divided on the
use of hide processors and also almost equally  divided  on  lime  and
unhair  liquor reuse.  Some tanners state that the leather produced in
hide processors is of poorer quality,  while  others  state  that  the
leather  is of better quality and the hide processors improve in-plant
control.  Some tanners think that hide processors are more  economical
because  less  labor  is required and lower water use results.  Others
object to the cost of installation and problems of maintenance.

In lime and unhair liquor reuse the  question  focuses  on  labor  and
materials  savings, lower waste load and questionable leather quality.
Several of the responses recorded on Table 21 in the  negative  column
included comments which indicated that decisions are still pending and
that further studies are being conducted.

Decisions  on  protein  recovery  apparently  depend  on  the economic
situation of  each  tannery.   The  important  question  involves  the
volume,  quality,  and  the  market for recoverable protein.   Reuse or


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              TABLE  21      IN PLANT PROCESS CHANGES INDICATED
                             ON QUESTIONNAIRE FROM TOTAL  OF  46
                             LEATHER TANNERIES
     PROCESS CHANGE METHODS

 Sulfide substitute in  unhairing

 Ammonium sulfate  substitute  in
   deliming

 Eliminate the bating step

 Use  of  hide processors

 Wash/soak water reuse

 Lime liquor reuse

 Unhairing liquor reuse

 Protein  recovery

 Spent chrome liquor reuse

 Liritan vegetable tan process

 Recovery of spent vegetable tan
  liquor

 Process or equipment wash water
  reuse

Cooling water reuse

Other
 NUMBER OF PLANTS
 WHICH CONSIDERED
BUT DECIDED AGAINST
  PROCESS CHANGES


        17
        12

        12

        14

        15

        12

         8

         6

        19

         5
NUMBER OF PLANTS
WHICH ARE OR WILL
 BE IMPLEMENTING
 PROCESS CHANGES

        0
        2

        0

       13

        7

       13

       10

        3

       10

        5


        8


       13

       14

        5
                                    148

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recovery of tan liquors is generally an economic  question  with  most
decisions  indicated  on  that basis.  From the questionnaires it also
appears that wash water and cooling water reuse is usually implemented
if convenient and if the tanner perceives some real benefit from  such
an investment.

Table 22 lists the more commonly used waste stream segregation methods
and  the  number  of tanneries reporting the use of these methods.  Of
the 46 plants whose input was  included  on  the  table,  nearly  half
indicate  using  one  or more of the listed beamhouse or tanyard waste
segregation methods.  Nearly half also indicate using one or  more  of
the  waste  stream segregation methods for specific tannery processes.
Tanners generally concede the value  of  segregating  certain  process
streams  for  reuse  of process liquor, for process chemical recovery,
and for more efficient treatment of final wastewater.  However, it  is
also  apparent  that  stream  segregation  must  be  tailored  to  the
individual tannery situation.  Some  tanners  do  not  consider  their
facilities readily adaptable to such renovations due to either limited
space  or  the type of construction employed in the original building.
Floor and sewer construction  methods  are  also  mentioned  as  being
particular problems.

It  is quite evident that many of these in-plant technologies are well
established and that a different cost situation   (e.g.,  the  cost  of
ammonia  removal  by  treatment  versus  elimination  by  substituting
chemicals) will motivate tanners to further implement these  pollution
control  methods.   As  the cost of processing chemicals and POTW cost
recovery and operating charges increase,  the  cost-effectiveness  for
many  of  these  in-plant  control  technologies will also become more
attractive.  Chrome recovery is an excellent example of  the  cost  of
processing  chemicals  making recovery economically attractive as well
as environmentally sound.

END-OF-PIPE TREATMENT

Preliminary Treatment - LEVEL 2

The need for preliminary treatment or pretreatment  is  based  on  the
following factors:

     1.   Removal  of  toxic  pollutants  found  to  pass inadequately
     treated through a POTW.

     2.  Removal of causes of treatment system upset or hazards and of
     collection system obstructions or potentially damaging materials.

     3.  Stringent water quality criteria imposed upon POTW  in  NPDES
     permits.

     4.  Reduction of load to secondary treatment units.
                                 149

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               TABLE  22      WASTE  STREAM  SEGREGATION  IN LEATHER-
                              TANNERIES AS  REPORTED  IN  QUESTIONNAIRES
                              FROM 46 PLANTS
                                  NUMBER OF TANNERS         NUMBER  OF  TANNERS
                                    WHO INDICATED             WHO INDICATED
                                   USE OF SPECIFIC           USE OF SPECIFIC
                                    BEAMHOUSE AND             PROCESS  WASTE
      METHOD OF WASTE STREAM        TANYARD WASTE          STREAM SEGREGATION
           SEGREGATION	    SEGREGATION METHODS             METHODS

Total number of plants reporting
 use of one or more of the               20                         20
 following methods
             ~"~~~~~"~~"~~~~~-~———————-—•—————————____________ __________ _ ________ _

 Below grade separate sewers
  or piping                              16                         9

 Above grade separate sewers
  or piping                              10                         9

 Diverters                               13                         g

 Collection trough                       10                        10

 Concentric bearings                      4

 Isolate  specific  process steps           -                         9

 Collect  specific  wastewater              -                        13

 Other                                    3                         5
                                   150

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     5.   Sludge disposal criteria.

Tannery  effluents  exhibit  a  wide range of pollutants and pollutant
concentrations.  Suspended solids vary from 300 to 14,000 mg/1 with an
average of 2,000-3,000 mg/1.30 5l The BOD5 of  tannery  effluents  can
vary  from  150  mg/1 to 3,000 mg/1, with an average of 1,000 to 2,000
mg/1.30 Grease concentrations in tannery waste can be as high  as  850
mg/1.   Sulfide and chromium concentrations also show a wide variation
in raw wastes.  Normal concentrations of lime and  chromium  salts  do
not  appear to damage the system; short-term high concentrations could
be  detrimental  to  biological   activity.    High   alkalinity   and
corresponding  high  pH  are  caused by lime discharges from beamhouse
operations.  Such discharges  normally  are  intermittent.   Trivalent
chrome  is  used  extensively as a tanning agent and hexavalent chrome
may appear in trace amounts.  Trivalent chromium salts are soluble  in
acid  and  neutral solutions.  For wastewaters with pH in the range of
8.0 to 10.0, trivalent chromium hydroxides are  highly  insoluble,  in
the range of 0.5 mg/1 or less, and will precipitate readily in primary
clarifiers.

Preliminary treatment operations consist of one or combinations of the
following operations and processes:

     1.  screening;
     2.  equalization;
     3.  sulfide oxidation;
     4.  carbonation of beamhouse wastewaters; and/or
     5.  ammonia nitrogen removal.

Screening.   Fine  screening  removes hair particles, wool, fleshings,
hide trimmings, and other large-scale  particulates.   While  reducing
undesirable  wastewater  constituents,  screening  contributes  to the
volume of solid waste which must be disposed.  The highly  putrescible
wastes  are  commonly  disposed  of  on-site  or  at  remote  landfill
operations.

Screening equipment includes  coarse screens   (bar  screens)  and  fine
screens,  either  permanently mounted  or rotating with self-cleaning
mechanisms.  An example is  the  three-slope  static  screen  made  of
specially  curved wires using the Coanda or wall attachment phenomenon
to withdraw the fluid from the  under  layer  of  a  slurry  which  is
stratified  by  controlled  velocity over the screen.  This method has
been found to be highly  effective  in  handling  slurries  containing
fatty  or  sticky  fibrous  suspended  matter53  and  is in use in the
leather tanning industry.

The  principal  function  of  screening  is  to  remove  objectionable
material  which  has  a  potential  for  damaging  plant equipment and
clogging  pumps or sewers.  To date, much of the screening  employed  in
this  industry  has not been  effective due to poorly operated screens,
or screens with openings that were  too  large,  or  both.   This  has


                                  151

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 resulted  in  continuing  operational  problems,  such  as clogging of
 pumps,  binding of  clarifier  sludge  rakes,   and  so  on.   Therefore
 effective fine screening is essential in all  cases.

 Equalization.     Equalization   of   waste  streams   is  important  in
 pretreatment facilities.   The  batch  nature  of tannery  operations
 creates  wide   fluctuations  in waste flows and waste strengths.   Such
 variations can be difficult to handle  and  may  result  in  over-  or
 under-design  of  the  preliminary and secondary treatment units.   The
 volume  and  strength  of  waste  liquors  vary  depending  on  process
 formulations  and  scheduling  of tannery operations.   Alkaline wastes
 are associated with beamhouse operations, while acid discharges  arise
 from the  tanyard.  In order to produce optimum results in subsequent
 treatment operations,  the equalization of flow, strength,  and  pH  of
 strong   liquors  may be necessary.   Although  some oxidation may occur,
 no  removal of  waste   constituents   is   normally   reported    for
 equalization.     Equalization  basins  provide  storage  capacity  for
 hydraulic balance.   Auxiliary equipment must  provide  for  mixing  and
 maintaining aerobic conditions.   Detention times should be determined
 based upon the wastewater generation patterns of the tannery  and  the
 requirements  of  the  secondary  treatment facility.   Typically  these
 patterns  run in 24-hour cycles.   In addition, most  tanneries  do  not
 operate  more   than  5.5  or  6   days per week.   Where a POTW does not
 receive sufficient  wastewater to  maintain an  active  biomass  in  a
 activated sludge plant,  additional  hydraulic  equalization capacity may
 be  necessary  to carry the  plant until  the tannery resumes production
 Basins  can be  monitored through  pH  and  flow measurement.

 An equalization tank or basin is  usually  fairly  large   and  is   most
 economical  at  low ratios  of  height  to surface area;  size is mainly
 subject to the  fact  that   effective  biological treatment  requires
 retention  of   wastewater heat.   Tanneries  with insufficient space for
 such a  tank  have another option.  This  option,  in use  by at  least   one
 tannery,   is   to schedule wastewater  dumps  from  the  tanning  facilities
 according to a  wastewater   discharge  schedule   that   is   designed to
 smooth  the  hydraulic loading on the  POTW.   When  scheduling of  dumps is
 combined   with   equalization tankage  providing   less   than   24   hour
 detention time,  significant  improvement  in  the    performance   of
 subsequent treatment processes is obtained.

 Sulfide   Oxidation.   Sulfides  in  the  beamhouse  waste constitute  a
 potential  problem because they will release hydrogen sulfide if  mixed
 with wastes which can reduce the pH of the  sulfide-bearing waste.

 The  removal of  sulfides is not accomplished with plain sedimentation.
 Sulfides are more satisfactorily removed through  oxidation.   Various
methods  for oxidizing sulfides include:

     1.   air oxidation;
     2.   direct chemical oxidation;54
     3.   catalytic air oxidation.54 55 s*


                                 152

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Air  oxidation  with  diffusers  provides  some removal, but only with
excessive aeration times.

Direct chemical oxidation  with  ammonium  persulfate  and  ozone  was
studied  by  Eye  and  Clement.5*  Ammonium  persulfate  produced  low
removals.  Ozone was most effective; however, the  expense  of  ozone-
generating facilities and developing contact equipment negated further
study.54

Studies  by  Chen  and  Morris56 revealed that many metallic salts are
effective catalysts  when  compressed  air  at  high  temperatures  is
utilized.   Manganous  sulfate  was the most effective catalyst in the
more alkaline solutions at near-ambient temperatures.  Nickel, cobalt,
and manganous ions also are effective, and potassium  permanganate  is
predicted  to  work  well.5*  Their best formulations achieve complete
removal with contact times as short as 15 minutes.

Kessic and Thomsom57 obtained 95 to 97 percent oxidation  of  sulfides
at  contact  times  of approximately 20 minutes using manganous ion as
the catalyst.  These solutions were very dilute and achieved  residual
sulfide  levels  between  0.3 and 1.0 mg/1.  In two studies, Ueno58 5«
obtained between 92 and  100  percent  sulfide  oxidation  using  high
temperatures,  great  excesses  of  air  and  many  different catalyst
systems.  Among those found to give good results were ferric  sulfate,
ferric    chloride,   activated   carbon,   carbon   black,   ammonium
peroxydisulfate, and hydroquinone.

Eye and Clement5* found that potassium permanganate plus  air,  ozone,
or  manganous  sulfate  plus air could remove sulfides completely with
contact times between 3 and 30 minutes.  In this study  a  first-stage
(continuous)   flow  reactor  removed  80 percent of the sulfide, and a
second-stage batch reactor removed the rest.  An actual tannery  waste
required  1.5  hours of treatment with potassium permanganate and air.
Bailey55 and Eye5* further describe the effectiveness of the  metallic
catalysts.   In  a  laboratory study54, potassium permanganate was the
most effective agent, with manganous sulfate also  proving  effective.
Although  the  relative  costs  for  the two catalysts favor manganous
sulfate, the available space and capital costs for the  two  different
systems  will  determine  which  catalyst  is  the  best  for  a given
situation.  Optimum results were obtained with a manganese to  sulfide
weight  ratio  of  0.15.   Pretreatment facilities employing catalytic
oxidation should approach 100 percent removal of sulfides.

Available information indicates that the catalytic  oxidation  process
can  be  designed to remove all dissolved sulfides.  However, residual
sulfur forms, which are chemically bound  to  organic  matter  in  the
wastewater  and  therefore  not  removed  by  this catalytic oxidation
process, can be subsequently redissolved  in  significant  quantities.
This  reappearance  of  sulfide  could  easily  occur  in a long sewer
collection system.   Further,  alternative sulfide control  systems,  such
as spent liquor reuse, will remove the majority of sulfides, but  will


                                 153

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 not  completely  remove  sulfides  without  the  addition of catalytic
 oxidation.  Sulfide recovery has been demonstrated at  full  scale  at


 Once  received in secondary treatment facilities, sulfides are largely
 removed.  However, in order to minimize dangers of potential  hydrogen
 sulfide  release  and to eliminate the immediate oxygen demand exerted
 in subsequent biological processes, a catalytic oxidation  process  is
 necessary for tanneries with sulfide-bearing wastes.

 Catalytic   sulfide   oxidation  can  achieve  complete  removal  (not
 detected)  of sulfide.  Sulfide liquor reuse or sulfide recovery (as in
 Tannery No.  444)  would assist in removal and provide  economic  return-
 however, it  is generally considered an optional measure to achievement
 of complete  removal of sulfides.

 Carbonation   of  Beamhouse   Waste Stream.   Carbonation is effective in
 the treatment of alkaline wastes.  In  this  process,  carbon  dioxide
 reacts   with lime to form calcium carbonate,  which has a solubility of
 only 25 to 50  mg/1.    The   crystalline  structure of  the  carbonate
 nucleus  provides  an  effective  surface  for  adsorption  of organic
 matter.   Suspended  solids   and  BOD5  are   both  reduced.    Inorganic
 suspended  solids  in  the  form of calcium  carbonate  are significantly
 reduced and  thus  reduce excessive alkalinity,   which   in  turn  reduce
 mixing   requirements  in activated sludge aeration basins and secondary
 sludge  production and dewatering requirements.

 Four U.S.  tanneries (numbers  60,  24,  58,  397)  have operated  flue   gas
or   carbon  dioxide Carbonation.   This technology  is used instead of a
strong acid, such as sulfuric acid, to reduce the  pH  of  the  highly
alkaline  waste  streams   from  the  beamhouse  operations.   Such  DH
reduction can be done for  a variety of reasons, such as to precipitate
excess lime, to neutralize the waste stream, and to provide sufficient
PH reduction to allow a substantial degree of  protein  precipitation.
Substantial  operating  cost savings can be realized by exchanging the
cost of  acid  for  the  cost  of  electrical  power  to  operate  thl
Carbonation system, primarily the  blower.

Stack gas containing 8 to  12 percent carbon dioxide, obtained from any
fuel  combustion  process,  can be used.  Introduction of gas into the
waste stream requires a suitable diffuser system and reaction  vessel
and continuous operation of the boilers.

Table   26  indicates  removals  of  suspended  solids  and  BOD5  for
carbonation  in  conjunction  with  coagulation  to  remove  dissolved
proteins  and  excess  lime.    The  BOD5  removals range from 65 to 92
percent, while suspended solids reductions from 79 to 99  percent  are
recorded.                                                 t^*^cnu  axe

Field  data  from tannery no.  24 indicate high reductions in suspended
solids,   BOD5,   and  total  alkalinity.    Estimated  flows  from   the
                                 154

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cattlehide  vegetable  tannery  were 1,700 m3/day (0.45 mgd) .  Primary
clarifier overflow rates were about 20.4 m3/day/m2 (500 gpd/ft2)  for a
chemical system utilizing flue gas carbonation and  a  combination  of
iron  salts  and  polymers.   (Sulfuric acid was also used to assist pH
control).  Table 23 presents the removals which were indicated60:


                               Table 23

     Performance of Flue Gas Carbonation and Chemical Coagulation

Pollutant
Paramater	Influent (mq/1)	Effluent (mq/1)	% Removal

Suspended           2,110               100                  95
 Solids
BOD5                1,660               270                  84
Total Alkalinity      640                 0                 100
 (as CaCQ3)	

Carbonation is attractive for tannery pretreatment  facilities,  where
carbon  dioxide  is  available  at  the  cost of piping from the plant
boilers.  Removals are high, under proper  operating  conditions,  for
suspended solids and BODJ5.

In  some  instances, pH control is a necessary adjunct to equalization
for  effective  removal  of  chromium,  prevention  of   sulfide   gas
evolution,  and enhancement of the protein/lime precipitation process.
Normally, this has been accomplished by feeding sulfuric acid, lime or
sodium hydroxide to lower or raise  pH  as  required.   This  requires
chemical  feeding  equipment  with  a  pH  sensing and control system.
Pumping equipment also may be required where tankage or  gravity  flow
constraints exist.

To  reduce  COD, BOD, nitrogen, dissolved solids, and suspended solids
from the beamhouse waste stream, various methods of  protein  recovery
have  been  successfully  demonstrated in tannery unhairing wastes.  A
typical spent unhairing liquid from  a  hide  processor  run  contains
about  8,000 to 9,000 mg/1 of TKN, most of which is contributed by the
denatured  hide  proteins.   Likewise,  the  total   volatile   solids
concentration  of  51,000  mg/1   (of  which  30,000  mg/1 are volatile
suspended solids  and  21,000  mg/1  are  volatile  dissolved  solids)
reflects the extremely high protein decomposition.

Happich,  et  al.,61  demonstrated  that  a recovery scheme employing:
removal of  suspended  solids  by  gravity  sedimentation,  screening,
centrifugation   and/or   filtration;  removal  of  soluble  inorganic
compounds by dialysis or ultrafiltration;  acidification  with  acetic
acid  to  pH  5.0  and  3.8;  and washing and drying; yields a protein
fraction of 90 to 92 percent purity.  These results were obtained from
lime sulfide hair pulping  effluent  samples  from  five  unidentified


                                  155

-------
 side-leather  tanneries   which  use  the  high-sulfide,   hair  pulping
 process.   First,  catalytic  oxidation  of the sulfide liquor removed the
 sulfides;  this was  followed by acidification.   Acid precipitation to a
 pH of  4.0  gave the  best  yield.   Sulfuric acid  has  also  been   used  to
 precipitate   the  proteins,  as  have chrome or pickle liquors.   However,
 care must  be taken  to avoid the  toxic  effects of  chromium  in  the
 protein  sources,  if the  by-product is intended for the feed industry.

 Happich  reported that approximately  30 percent of the COD (37  percent
 of BOD5) present  in the  untreated hair-burn waste  was separated in the
 solids   fraction  after   a   two-stage  centrifugation.    Another  31.5
 percent  of   the  COD  (34.9  percent  of  the  BOD5)  ultrafiltration
 transferred  to the  filtrate, and 38.5 percent  of the  COD (28.1  percent
 of the BOD5)  was  actually removed  with  the  protein.    According  to
 Happich,   effluent   COD   decreased by 70 percent and  65  percent of the
 protein  in the effluent  was recovered.   The product could be   purified
 to 90 percent protein by reprecipitation.   The amino acid composition
 did not  differ significantly  from the  protein  recovered  from  un-
 oxidized lime-sulfide unhairing effluent.

 Happich  noted that  the  recovered   protein   contained the  hair.   He
 concluded, however,  that the recovered hair protein was  low in  most of
 the amino  acids found in whole  egg protein and  would   require  some
 supplementation  for  subsequent use  as feed (typically  for chickens).
 Once properly supplemented,  autoclaved cattie-hair has proven to be  a
 satisfactory  source  of protein for feed  formulations.   If  no market
 for feed formulas exists near a tannery,  however,  the protein   sludge
 may be  dewatered   on   a  gravel bed filter and sold as  fertilizer or
 taken to a landfill  site for disposal.

 Van Meer experimentally  tested  segregation  of  specific process  streams
 for reuse or  treatment.*2   Wastewater  volume   and COD   and  nitrogen
 loading  were   substantially  reduced,  the  former  to  3-4  I/kg hide and
 COD and nitrogen  from this  source by  89 and 90  percent,   respectively
 This  method   carries  out the unhairing in  the  first  soaking  liquor or
 in  a separate  short  float.   The  initial wastewater  treatment  consists
 of  catalytic   oxidation  of  the sulfides  with manganese  sulfate  and
 aeration.  This is followed by  acidification with   sulfuric   acid   and
 sodium  chloride  to  pH  4.0   and precipitation of the proteins.   The
 resulting sludge  is  then either  dried on a  gravel  bed or  filtered  from
 the effluent in a sand filter.    The recovered sludge  can  be used as  a
 fertilizer  or  feed source.  The COD and TKN in the  combined soaking,
 unhairing  and  wash  liquors  after  acidification,  were  reportedly
 reduced 84  and  86 percent, respectively.

A   leather   tannery  waste  management  studya* conducted under an  EPA
 grant in tannery no. 431 reported on  experiments in  the  recovery  of
 crude protein  from unhairing liquors:

     "To  determine  the degree of effluent reduction possible through
     protein recovery from manganese catalyzed, air-oxidized unhairing


                                  156

-------
wastes,  a  sample  of  oxidized  waste  from  an  early.«.paddle
aeration  run  was  sent  to  the  U.S. Department of Agriculture
Eastern Regional Research  Center  in  Philadelphia  for  protein
recovery  by  a  modified  treatment  scheme.   Precipitation  by
acidification of the sample to pH 4.2 yielded a tan color protein
of 80% purity.

"Another bench-scale experiment was conducted...to further define
the  conditions  for  optimum  precipitation   of   protein   and
subsequent reduction of contaminant levels.

"Concentrated  hair-burn  liquor was air-oxidized using manganese
sulfate as the catalyst, at  a  Mn++/S=  ratio  of  0.15.    After
oxidation,  the  liquor  contained  approximately 160,000 mg/1 of
total solids, of which 58,400 mg/1 was suspended solids.

"Varying levels of concentrated H2SQ4...were  added  to  eighteen
500  ml  aliquots  of the oxidized waste.  The samples were mixed
using a Phipps and Bird laboratory stirrer for 5 minutes  at  100
rpm  followed  by  5  minutes  of "slow" mixing at 50 rpm.   After
settling for 60 minutes, the supernatant  liquids  were  decanted
and  analyzed  for  pH,  total  solids and suspended solids.  The
pH(s, which varied from 0.3 to 9.4, were consistently higher than
the expected values.  This  is  most  likely  due  to  the  times
elapsed in the precipitation runs contrasted to the 10-15 minutes
required  for the original titration.  While there is no apparent
relationship  between  supernatant  pH   and   suspended   solids
 (supernatant  suspended  solids  concentrations were consistently
within the 280-630 mg/1 range except at pH 9.4 where  a  markedly
increased  level  of  1,670  mg/1  was  observed) the optimum for
reduction of total solids  (was found to be)...within the  0.9  to
5.0 pH range.

"The  volumes  of the resultant sludges varied from 300 ml to 475
ml with the minimum  lying  within  the  1.0  to  3.9  pH  range.
Fortunately,  this  range of minimum sludge volume is also within
the optimum range for precipitation of protein.

"At pH 3.2, the supernatant analyzed at  100,200  mg/1  of  total
solids   (minimum  observed for 18 runs) and 401 mg/1 of suspended
solids.  Thus, approximately 75% of the total solids and 99.7% of
the suspended solids present in the original, air-oxidized  waste
sample  were  transferred  to  the  300  ml sludge fraction after
precipitation and settling.

"Undoubtedly, further  sludge  dewatering  will  be  required  to
concentrate  those  solids  which  occupied   60%  of the original
sample volume.  Since a portion of the  sludge   (which  contained
approximately 80% moisture) dewatered readily by gravity on a 18-
mesh   screen,   dewatering   methods   recommended  for  further
investigation include gravity screening and sand bed  filtration.
                             157

-------
      Lab-scale attempts at vacuum filtration failed to generate a firm
      cake  indicating  that conventional rotary vacuum drum filtration
      is not a feasible alternative.  As indicated  (previously)   these
      concentrated  hair-burn liquors comprise only a small fraction of
      the total wastewater flow (i.e. , approximately 11,700  gal  hair-
      burn  liquor  vs approximately 1.5 million gal total daily flow)
      yet contribute substantially to pollutant  loadings.   Therefore
      it appears from these results that precipitation of crude protein
      from  oxidized unhairing wastes can effect significant reductions
      in total plant  loadings  provided  adequate  methods  of  sludoe
      dewatering and disposal can  be demonstrated."

 The  effectiveness  of flue gas carbonation of beamhouse waste streams
 is optimal  when the PH is lowered  to  the  isoelectric   point.    when
 limited  to   only  the   introduction   of  flue  gas,   the  treatment
 lu of ^!neSS    t^1S g?05;ess wil1 not  be ^ great since the operating
 PH of the process is  higher  than  the  isoelectric  point.    Removal
 efficiencies   were  conservatively  selected  to  represent  expected
 performance in this industry,  as  follows:   BODS -  60 percent,   where
 removals  as  high  as 84  percent were noted ;~TSS -  65  percent,  where
 removals  higher than 95 percent were noted;  COD -  60 percent   where
 removals  of as high as 90 percent or more were noted; oil and grease -
                          and TKN - 65 percent- where

        Nitrogen Reduction.   Ammonia  is  difficult  to  remove  from
tannery  wastewaters.   Biological  systems  which remove BOD have not
seen effective in removing ammonia.  For this level of treatment.  EPA
wastes"^  ohvsi^T aite?na*i ves  for  removing ammonia from Seiimfng
wastes  by  physical-chemical  treatment   processes.    The   ammonia
introduced  into the tannery wastewater stream by the deliming process
ranges from 67 to 90 percent of all the  ammonia  in  the  raw  waste
str!amSUwflf ^^f* ^^ °l treatment °f this ammonia containing
wastewat«         "   "                                            *
These processes assure that the primary ammonia containing  stream  is
«H£f9aJ:ed  and  vte  ammonia removed before it is combined with other
waste streams.  The segregated ammonia containing stream has a  hiaher
concentration  of  ammonia than a combined stream, and it is therefore
       t0 treat by Physical-chemical methods.  Th4 methods  consilerel
     1.    water   evaporation   followed   by    crystallization
          precipitation of ammonium sulfate;

     2.    distillation of ammonia;

     3.    precipitation of ammonia  as calcium ammonium phosphate;
or
                                 158

-------
     4.   precipitation of ammonium sulfate by addition of ethanol;

     5.   reverse osmosis; and

     6.   ion exchange.

No tannery  now  uses  these  methods  for  treating  ammonia  wastes.
Several of them are technologies used in other industries while others
should  work  because  of known chemical principles.  Use of alternate
deliming agents has been discussed in the In-Plant Control portion  of
this Section.

     Evaporation/Crystallization

     Evaporation  plus precipitation is a well-known technology and is
     used to prepare many solid chemical  products  from  aqueous  and
     organic  solutions.   This  technique  evaporates  water from the
     deliming  waste   until   the   ammonium   sulfate   concentrates
     approximately  at  the saturation value.  The ammonium sulfate is
     then  crystallized  by  cooling  the  solution  and  removing  an
     additional  small  amount  of  water  by  applying a vacuum.  One
     disadvantage of this process is that relatively large amounts  of
     water  must be evaporated.  For example, if the segregated stream
     contains 1 percent ammonium sulfate, then  the  concentration  of
     this  stream to the saturation point of about 50 percent requires
     evaporation of about 98 percent of the  stream.   The  evaporated
     water  will  contain  about  0.2  percent ammonium sulfate if the
     evaporation occurs at about  95°C.   Thus,  the  percent  of  the
     ammonium  sulfate  removed  will  range  from  60  percent if the
     original concentration was 0.5  percent  to  90  percent  if  the
     original  concentration  was  2  percent.   Energy  costs  are  a
     significant limit on this process,

     Distillation

     Distillation  is  well-known  and  widely  practiced.    If   one
     component  of  a  mixture  has  a  higher vapor pressure than the
     others at a certain temperature then boiling the mixture at  this
     temperature  will  concentrate the more volatile component in the
     vapor phase.  Addition of a strong base to  deliming  waste  will
     convert  most  of  the ammonium sulfate to free ammonia, which is
     much more volatile than water.  At 25°C ammonia is so  much  more
     volatile  than  water  that  removal of 90 percent of the ammonia
     requires evaporating only 8.5 percent of the water; removal of 99
     percent of the ammonia requires evaporating only 16.3 percent  of
     the  water.   It   is  important to distill at the lowest possible
     temperature because the relative volatility of  ammonia  compared
     to  water decreases as the temperature  increases.  A disadvantage
     and serious limitation in this method is that the ammonia  cannot
     be  economically   recovered after distillation and must be vented
                                  159

-------
 into the atmosphere,  causing unacceptable odor and consequent air
 pollution problmes.

 Precipitation with Phosphate

 The fact that calcium ammonium sulfate is insoluble in  water  is
 the basis for predicting the possibility of precipitating ammonia
 with  phosphoric  acid  if  the proper amount of  lime is present.
 The insolubility of the  calcium  ammonium  sulfate  salt  causes
 difficulties   in the  production  of  the  fertilizer   ammonium
 phosphate.   It is possible  that  excess  lime  would  cause  an
 increase  in  the cost of this process.   Calcium  phosphate is not
 very soluble  in  water  and  would  precipitate   from  solutions
 containing lime and phosphoric acid.   It may thus be necessary to
 precipitate excess lime by flue gas carbonation before attempting
 to remove the ammonia with phosphoric acid.

 Precipitation with Ethanol

 Ammonium  sulfate is insoluble in solutions of ethanol  and water
 if the   ethanol  concentration  is more  than  approximately  90
 percent.    Thus,   it  is possible to predict  that  ammonium sulfate
 can be precipitated from water by adding nine parts  by weight  of
 ethanol   to  each part of ammonium sulfate solution.   The cost of
 ethanol,  however,  precludes  further consideration.

 Reverse  osmosis

 Reverse  osmosis can concentrate  aqueous  solutions  of  salts.   A
 cellulose   acetate membrane   suitable   for  producing  fresh water
 from seawater  or   brackish water   would  be suitable   also   for
 concentrating   aqueous   ammonium   sulfate.    Free  ammonia  would
 probably  go  through such a membrane.  Pressure  requirements   are
 the  main  limitation on  how much the ammonium sulfate solution  can
 be   concentrated.   Concentration to even  5  percent would require
 the  use of several hundred psi.  Fouling  could also be a  serious
 problem.  Cost  and process limitations preclude this from further
 consideration.

 Ion Exchange

 Ion  exchange has been used to remove small amounts of impurities
 from water.  To remove ammonium ion, exchange  with  an  acid  is
necessary.   Suitable   resins exist, but again fouling could be a
serious problem which, along with cost, minimizes   the  potential
for application of this process.
                            160

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 Primary Treatment
 Plain  sedimentatipn.   Plain  sedimentation  is  concerned  with  the
 removal of  non- flocculating  discrete  particles  and  flotable  low-
 density  materials  such as grease and scum.  Tannery wastes have high
 concentrations of both suspended solids and grease.  As shown in Table
 oercentPend.hdi S°U^ r?ductions c™ «nge from approximately \0 to  90
 Mnoh ^Kv,   l6  rfductlons  in  BOD5 can range from 30 to 60 percent.
 Much of the suspended material removed is in  the  form  of  insoluble
 lime  which  produces  a voluminous and heavy sludge?  Although grease
 removals are not indicated, high removals are  expired  wi?h  surf acl
 skimmers installed in clarifiers.                              surtace

 Sutherland  cites  the  operation  of  full-scale  plain sedimentation
          ^"-entation reduced the suspended solids content of a  side
                                                         *>  370
 Laboratory experiments by Sproul, et  al^*  utilizing  beamhouse  and
 chrome  liquors showed that plain sedimentation at an overflow rate of
 24.5 ma/day/m^ (600 gpd/ft*)  gave average removals of about 22 percent
 of suspended solids and 35 percent of BODS.  Pilot  scale  experiments
 by  sproul,  et a^" show that equalization of plant flows fol lowed bv
    ln  ed*        gaVe sus?ended solids and BOD5 removals up  to  99
 nd50  ~
o? i-h» * m? ' resPe=tlvely-  Chrome liquors in excess of 1 percent
of the total flow proved to be an effective  coagulant  for  comoosi^
                                                          or  comoos
 wastes  containing 2,000  mg/1  suspended solids.   Overflow rates^f If 3
 m3/day/m3  (350  gpd/ft^)  produced  a  2  percent underflow concentration!

 Field   operations at tannery  no.  237  tend to confirm these  removals. 30

 ratef^f^Tfl^ T^^^  tW°  circular  clarifiers  with   overflow
 mt/IL  ,0  8 £;5,  m^day/ni% . ^6°  gpd/ft^)  at an average flow of  1,030
 m /day  (0.8 mgd) .  NO equalization  facilities are provided  other   than
 mixing   in a pump wet well.   Cattlehide processing during the samolina
 period  averaged  81,700 kg  (180,000  Ib)   green- sal?ed  and  brine-cured
 tan f /^ -da^   f°r hair  pulp be^house operations  followed  by chrome
 tan and  finishing.  The  following average removals resulted^o

                               Table  25

     Pollutant Removals by Plain  Sedimentation at  Tannery No.  237
Paramater	Influent  fmcr/1)     Effliren*  fr^/i]

Suspended Solids    3,125
                    2,108
Total Chromium         51
Total Alkalinity      980                 /1H               0-
 (as CaC03)                                                  27
Grease	490	   57	    go



                                 162

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Suspended solids and BODJ5 removals were 70  percent  and  45  percent,
respectively.   A  low  chromium  removal  of approximately 50 percent
occurred.  Higher removals would result if a pH of 8.5 or greater were
maintained (using equalization or chemical addition)   in  the  primary
clarifiers.   If sodium alkali is contributing to the high pH, a pH of
10-10.5 may be needed for best removal.   Theoretically,   all  chrome
should precipitate as chromic hydroxide; however, a very small residue
is   expected.    Although  chrome  removal  from  the  wastewater  is
desirable,  it  does  create  a  sludge  problem  if  proper  disposal
precautions  are  not taken.  Total alkalinity was reduced 27 percent,
reflecting sedimentation of suspended lime.   Grease  removal  was  90
percent.

Coagulation -Sediment at ion.   Chemical  addition prior to sedimentation
of combined wastewater  streams  has  further  increased  the  removal
efficiencies  of primary clarifiers.  This is a key step in removal of
insoluble  toxic  pollutants,  most  importantly  chromium.   Chemical
coagulation  results  in  higher  removals  of suspended solids, BODJ5,
sulfides, chrome, and alkalinity  through  flocculation  of  colloidal
particles.   Alum,  lime,  iron  salts,  and  polymers  have exhibited
satisfactory  results.   Table  26  indicated  that  suspended  solids
removals   from  50  to  above  98  percent  and  BOD.5  reductions  of
approximately 50 to 99 percent are achieved.

Chemical coagulation followed by sedimentation has been applied  at  a
plant  using  the  chrome  tanning  process.*4 Raw wastewater analyses
indicate concentrations of BOD5 at 2,500 mg/1 and suspended solids  of
about  2,530  mg/1.   The  results  drawn  from  the  laboratory-scale
investigation were shown in  Table  26.   Other  chemical  coagulation
results were as  follows:

     1.   Use  of  an  anionic  polymer  at  a concentration of 1 mg/1
     resulted in a reduction of about  84 percent in  suspended  solids
     and 60  percent in BODj>.

     2.   Adjustment  of  the  waste   to pH  9.0 with sulfuric acid and
     subsequent  settling gave average  removals  for  suspended  solids
     and BODJ5 of 90 and 67 percent, respectively.

     3.    Use  of  ferric  chloride  at  a   concentration  of 600 mg/1
     produced average removals of 60 and 65  percent, respectively, for
     suspended solids and
      4.  Ferric  chloride coagulation was  less  effective  in removal   of
      suspended solids than was  adjustment to the  same  pH with  sulfuric
      acid.

      5.   Ferric chloride removes   dissolved   sulfides,  but   chemical
      costs  are high.
                                  163

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                                                                164

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     6    Coagulation  with  alum at concentrations less  than 500  mg/1
     after adjusting to a pH of 6.5 reduced the BOD5 by 90 percent and
     suspended solids from 45  to  57  percent.   Alum  concentrations
     higher than 500 mg/1 created a floe that would not settle.

     7.    Buffing  dust  resulting from finishing tanned hides was not
     found to be an effective coagulant.

In general, polymer addition  produced  a  rapid  formation  of  floe,
minimizing   the   need   for   flocculating  equipment.    Without  pH
adjustment, polymers produced consistently higher removals than  other
coagulants tested.

Sulfides  appearing  in  the  pretreatment influent are not completely
removed in chemical units.  Inconsistent removals are indicated in the
literature by researchers.** 64 65 with pH adjustment to 8.0, an upper
limit on sulfide removal may be 90 percent.* « Sulfide removal  reduces
oxygen demand and averts hydrogen sulfide problems.

Chromium  will  precipitate as a hydroxide most effectively at a pH of
approximately 8.5.  A  90-percent removal  in  a  laboratory  study  by
Sproul, et al.6* occurred at a pH of 8.0.

In  pilot  plant coagulation and sedimentation operations described by
Howalt and Cavett** and  also by Riffenburg and  Allison*^  93  and  99
percent removals of color were observed, respectively.

A thesis  by   Hagan*8,  investigated color removal  through coagulation
and precipitation.  In coagulation,  inter-particle  attraction  created
by  suitable  polymer  develops a  large  floe  that tends to settle  at an
optimum pH.  Hagan  also  reported that the  common-ion   effect   assisted
in  precipitation   removal.    The  basis of this  contention is  that the
hiqh  hydroxyl ion concentration  at high pH reduces  the  solubility  of
color  vectors   such  as   digallic acid,   which  contains   hydroxyl
functional groups.   Addition of  coagulants   and   pH  control   at   this
point further increase the  relative efficiency.   Laboratory  results on
a vegetable  tannery   waste indicate  high color  removals (94  percent)
through a combination  of chemical  precipitation  and  coagulation   with
calcium    hydroxide and  an  anionic   polymer.*°   The  efficiency is
dependent on  pH control around 12.   Many low removal may have resulted
from inefficient control of the   physical-chemical  operations,   ;:..ich
require  operator attention to  be successful.

Based  upon  the  above  performance  data,  the following removals are
considered achievable with the implementation  of  carefully  operated
coagulation-sedimentation:    BOD5 - 60  percent,  where removals as high
 as 85 percent were noted; TSS -  60 percent,  where removals as high  as
 99  percent  were  noted.   As noted in Table 26, removal efficiencies
 greater than 90 percent have  been  noted  but  not  used  because  of
 dissimilarities in technology such as the use of two stage systems and
 use  of  very  high chemical dosages of costly chemicals, such as 5000


                                  165

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             HS™^~
      "

 "Secondary" Biological Treatment - LEVEL 4
As mentioned previously, preliminary treatment and  primary  treatment








































        £iiter  Process.  very  few  tanneries and some POTW's use
                                                  s use









A trickling  filter  is  an  aerobic  biological unit.   Wastewater

constituents   are brought in contact with  a microorganism  mass
                         166

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developed on the  surface  of  the  filter  media.   To  achieve  high
removals  from tannery effluents, toxicity and excessive organic loads
must be avoided.   Lime  deposition  on  filters  also  has,  in  some
instances,  retarded  biological activity.  Also, the high strength of
tannery wastes  requires  the  provision  of  a  large  surface  area.
Although  recirculation  and  improvements  in filter media may reduce
overall area  needs,  waste  load  reduction  may  not  be  consistent
throughout the year to meet the demands of future effluent limitations
requirements.  Temperature is critical in operation.  High heat losses
can  occur  in the spray distribution system and across the bed media,
yielding low efficiencies.  Populations of nitrifying  organisms  will
be  suppressed  by  continual  dosing  of the system with carbonaceous
organic material.

Two tanneries in the southeast have indicated that they  are  using  a
trickling  filter  or trickling filter-like system as one component in
their secondary treatment system.  Tannery no. 400 uses a  rock  media
filter  as  the  first  stage  in a two-stage biological system.  This
tannery does not have an unhairing step.   The  purchased  hides  have
been  previously  unhaired and prefleshed.  The tannery is a vegetable
tannery using the "Liritan" process.  Data on the  reduction  of  BOD5
and suspended solids across the trickling filter is not available.

Another   southeastern tannery  (no. 24) also uses a trickling filter as
the first stage in a two-stage biological  system.   Operational  data
reported   in  1972  indicated  that  the  plastic  media  filter  was
ineffective, with removals of less than  30 percent BOO5 and  suspended
solids.   Kinman*9 reported improved operation of the overall system by
cleaning  the  media  and  increasing  the  air   supply to the  filter.
Confirming data obtained in a recent  field survey at  Tannery   no.  24
indicate  that  the  trickling   filter   (oxidation  tower),  including
secondary clarification, has the  combined performance  characteristics
displayed in Table  27.

                                Table  27

       Performance Characteristics of  Trickling  Filter Treatment
                        for Tannery Wastewaters
Influent to
Pollutant Trickling Filter
Parameter (mq/liter)
BOD5
Suspended Solids
COD
Total Kjeldahl
Nitrogen (as N)
Ammonia Nitrogen
(as N)
270
110
Effluent From
Clarifier
(mq/liter)
62
45
240
210
60
Removal
(percent)
77
59
                                  167

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 The  flow  to  the  filter  was  approximately  4,000  m3/day  (1 mad)
 con             +- «*. 8»H>ended solids may not be possible due to  the
 colloidal  characteristics of the suspended material and the relativelv

 cUri?Ier      "^ °f " m3/day/m2  <800  *><"«">   ^  thl  secondary
 Trickling   filters  have  limited application in the treatment of high
 ov3*rf tann"y w^tes.  system upsets  are  common  due  to  organic
 overload    and   climatic   conditions.    Existing   filters  mav  h«
           system
 tasasas.     Lagoons,   also   referred   to   as  oxidation  ponds   or

     availaW*  *%£*' ^ ^^ "sed for tannery treatment  where land
     available   and  where  la
  s  availaW*                                                      n
 is  available  and  where  land  values  are  low  enough to make laaoon
 systems an economical alternative to activated  sludge!  LagoonI  slrve
 two   purposes:   egualization   and  the  provision  of  a  desirable
 environment for biological activity.   In  a  large  lagoon  with  a
                                                  9
s             1                        clarificationmay
whfi/h  mU  ti0n'  however'  can Deduce the efficiency to the poini
where it becomes necessary to construct  a new lagoon or dredge the old


There are three  types of lagoons based on the  biological  environment
that exists for  the stabilization of organic wastes.  These types are:

     Aerobic  Lagoon— Biological  stabilization  in  the  presence  of

                                            -SJSST sss.r-s
                           the dissolved oxygen content in the llgoonf

2.    Anaerobic Lagoon— Biological  stabilization in the absence of free
     oxygen.

3.    Aerobic/Anaerobic  Lagoon— A  stratified  lagoon  where    aerobic
     activity  predominates  near  the  surface and anaerobic activitv
     takes  place near  the bottom of the lagoon.      anae^ot)ic activity
            em°n!trati0n at a tanner* in Virginia,  Parker  investigated
denitrification,   as   indicated  b                            •       '
         ation,  as  indicated  by  reduction   of   KM   •*     '
                                168

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systems.   The  aerobic  lagoon  is followed by anaerobic treatment in
another lagoon to reduce the  nitrate  to  nitrogen  gas,  which  then
enters the atmosphere.

Thirteen  tanneries surveyed presently treat their waste with lagoons,
either as pretreatment, major method, or finishing step to some  other
system.  Several tanneries indicated that lagoons are only a temporary
treatment  while  other  more  efficient  systems are planned or being
built.  Eleven of the thirteen  tanners  use  mechanical  aeration  of
their   aerobic  or  aerobic/anaerobic  lagoons.   Aeration  increases
dissolved oxygen content and thereby reduces retention time or  lagoon
size,   which   saves   on   land  requirements.   Four  tanners  have
aerobic/anaerobic lagoons while three others are equipped with  multi-
stage  aerobic and anaerobic lagoons.  Nearly all  (85 percent) provide
screening of wastewater and 38 percent are using  plain  sedimentation
or coagulation-sedimentation as a primary treatment before discharging
into   lagoons.   Several  tanners  reported  adding phosphoric acid to
provide  an  adequate  nutrient  balance  for   effective   biological
activity.

A  major disadvantage of using aerobic lagoons  to treat tannery wastes
is the decrease of efficiency during the winter months, especially  in
the  northern  states.   In  addition,  ice  cover can inhibit aerobic
conditions.  A northeastern tannery  (no. 401)   reported  the  data  in
Table  28, which exemplifies the seasonal variation in effluent quality
from their lagoon system:

                               Table 28

          Aerobic Lagoon Performance as a Function of Season


Pollutant      Summer and  Fall     Winter and  Spring
Paramter	(mg/liter)	(mq/liter)	

BOD5                 15                    98
COD                 176                   398
TSS                  19                     85
Cr                   0.7                    3.5
Grease              26                    43
TKN                  39                    65
Sulfide 	0.2	O.JJ	

This  data   typifies the  shortcoming of aerated or aerobic lagoons for
treating leather tanning  wastewater.   The extensive surface  area  for
heat  dissipation and the low solids (microbial population)  content of
the  lagoons  precludes consistently good effluent quality during winter
 months.

 Anaerobic lagoons are usually covered to retain the heat so  they  are
 less affected by low ambient temperatures.   A scum layer of grease may


                                  169

-------
 accumulate  on  the  surface  to reduce heat loss and ensure anaerobic
 conditions.  Polyvinyl chloride, Hypalon^, and  styrofoamj,  have  been
 used to cover anaerobic lagoons to retain heat, control odor, and in a
 few   cases  to  attempt  collection  of  methane  gas.   For  optimum
 ohnn?r£n0!; *? K^ redUSe °d°r Production, the PH of anaerobic lagoons
 should be kept between 7.0 and 8.5.  Anaerobic lagoons are used by the
 method indU3try as One part of a system and not as the sole treatment

 Under the proper biological conditions, i.e., pH  control,  sufficient
 nutrients,  etc.,  and  with  long  retention times (usually requiring
 large amounts of land in relation to plant size),  lagoons can  provide
 consistent  effluent  quality  in  warmer  climates.    Land values and

 alternate^  *?**?  ^^  lag°°nS  ***  m°re   economical   than
 alternate  treatment systems.  In colder climates  winter operation can
 never approach summer treatment efficiency,  unless they utilize costly
 covers,  or the system has sufficient storage capacity to hold  several
 months discharge.

 Activated  Sludge Systems.   The activated sludge process is one of the
 most controllable and flexible of all secondary treatment systems.  It
 is applicable to almost all treatment  situations   and  plays  a  very
 important  role   in  this  industry for treatment  of  toxic pollutants?
 With proper design and  operation,  high organic  removals  are  possible
 Designs   based on solids  retention time (SET) afford  optimum residence
 time for  solids  with minimal  hydraulic  retention.    However,   pilot
 studies   are  required  to   establish  appropriate design  parameters
 wastewaLr   rel*tive rate  °f biological growth and decay wiL  a given

 Basically,  the activated  sludge   process  consists  of:     mixing of
 returned   activated  sludge  with the  waste to be treated;  aeration and
 separation of  the  activated  sludge  from  the mixed  liquor   and disposal
 ?n™   excess. sludge.   Activated sludge  is typically preceded by  some
 form   of   primary  treatment,  especially  in  tannery   applications
 ovf^tnn  ln P2^6**™:1^ may  include  the use of equalization, sulfide
 some* form'of SSe^^' ***™™^™  or  clarification,  and
Based  on  the  influent  and effluent data from samples collected and
analyzed during this program,  BCD5  removal  varied  from  89  to  98
fromenQO  ?oaCQ«Vated Sludge Svstems'  Suspended solids removal ranged
from  90  to  98  percent.   BOD5  measurements  of  filtered  samples
indicated the significance of solids removal and hence the  import an ce
of the size and design parameters for the final clarifier.  Successful
                                                         .
of r?a.?n f the activated <*«** treatment system depends on a number
of  factors  such  as:  continuity  and uniformity of feed by means of
equalization  whether provided by a separate equalization tank  or  by
the  design of the aeration basin, maintenance of nutrient balance and
high  mixed  liquor  solids  in  the   aeration   basin,   and   linal
                                 170

-------
clarification  designed  for  very  low  overflow rates for removal of
suspended solids.

Tannery no. 237 in  Minnesota  has  initiated  full  activated  sludge
operations for an estimated 3,600 m3/day (0.95 mgd) flow from a chrome
tanning,  hair  pulp  facility with finishing operations.  The project
was partially financed  through  an  Environmental  Protection  Agency
grant.    The   system  at  Tannery  No.  237  uses  screening,  plain
sedimentation,  activated  sludge,  final  clarification  and   sludge
filtering.

The  combined  tannery  flows  are screened, then pumped to dual plain
sedimentation  basins.   The  12-m  (40-ft)   diameter  clarifiers  are
equipped  with surface skimmers.  Four concrete lined lagoons are used
as activated sludge aeration basins.  Each lagoon has  a  capacity  of
3,875 m3  (1 mil. gal.) at 1.8 m  (6 ft) operating depth, which may vary
in  operation.   Three lagoons are operated in parallel and the fourth
lagoon functions as a sludge digester.  An aeration capacity of 60  hp
per  lagoon  was  installed.   Return sludge design permits recycle to
each lagoon as well as ahead of the primary clarifiers.  Aeration  and
digestion  are  followed  by  final  sedimentation in two 12-m  (40-ft)
diameter clarifiers.  The effluent is chlorinated prior  to  discharge
to  a  nearby  watercourse.  Primary sludge and waste activated sludge
are dewatered in a pressure filter and landfilled on-site.   Automatic
samplers  permit  monitoring  of  individual treatment units to ensure
better operational control.

Data for this activated sludge system at plant no. 237 shows more than
90 percent removal of BODj> in the summer months and 90 percent removal
of suspended solids  (final effluent BOD_5 concentrations ranged from as
low as 8 mg/1 to as high as  489  mg/1);  EOD5  and  suspended  solids
removal   decrease   somewhat   in  the  winter.   Wintertime  removal
efficiencies are:  BODj>—89  percent;  suspended  solids—88  percent.
EPA  believes  that  these  results  do  not  accurately  reflect  the
achievable final effluent  concentrations   (i.e.,  BODji>  and  TSS)  of
activated  sludge  systems  since  a  number of design and operational
factors contributed to poor performance, such as lack of equalization,
very shallow aeration basins with inadequate  mixing,  under  designed
secondary   clarifiers,  frequent  changes  in  experimental  mode  of
operation, presence of significant quantities of sulfides from primary
treatment, and other factors.

EPA evaluated a  full-scale  activated  sludge  plant  in  a  Kentucky
tannery   (No.  47)  in a two-week study.  This tannery is a cattlehide
tannery with pulp hair beamhouse operations and alum tanning with some
chrome and vegetable tanning.  At the time of the study, flow  was  61
m3/day   (0.016  mgd).   The  treatment  system  consists of screening,
primary  clarification,  extended  aeration  activated   sludge,   and
secondary  clarification.   Primary  treatment  includes  a  rotating,
coarse screen followed by fine  screening  and  24-hour  equalization.
Overflow  rates  of 13.6 and 13.4 m3/day/m2  (290 and 285 gpd/ft2) were


                                  171

-------
 observed in primary and secondary clarifiers, respectively.  Hydraulic
 detention time averaged 1.6 days in the aeration basin.         "unc

 Additional data from sixty  months  of  operation  indicate  long-term
 average  effluent  performance  in the range of 60 mg/1 of BODS and 95
 mg/1 of TSS.  Variability showed no seasonal influence, but rather the
 influence of  equipment  failures  or  shock  waste  loads!   This  is
 f^TV •   significant  since  all  system  equipment is located in a
 flood plain and is therefore above ground and exposed to the elements
 thus exacerbating the potential for temperature influence.   eieinen1:s*

 An activated  sludge  facility  in  New  York  (tannery  no.   320)   is

 finisM™  ^a^nl  ?ffluent  f*om a save hair beamhouse, chrome tan,
 finishing,  and rendering  operations.   Total  wastewater  from  thes4
 processes is about 1500 m3/day (0.4 mgd).   Combined flows are screened
 ?  ?Q7/i   equalization.  The equalization  basin had a 24-hour capacity
 ^r-i^  J   unclarifi?d discharge from  the  equalization  basin  is
 directed  to  an  aeration  basin with approximately 12-hour  detention
 /oon ?? °rgtn*c load to the basin of about 3600 kg per day per 1000 m3
 nf ?a + ^'^y/1'000  ft»).   The final clarifier hL an overflow rate
 of 24 to 28 m3/day/m2 (500 to 600 gpd/ft2) .                  ^J-uw tdte

 An  organic  removal of  80  percent  produced   an   effluent   BOD5
 concentration  of   343   mg/1  and  suspended  solids  reductions of 92
 percent.  Effluent suspended solids  concentrations  of  190   mg/litre
 *£l   5*i  lnff?ec^iye solids capture in the final  clarifier.   The pH of
 the  effluent is 8.0 to  8.5.   The  most  interesting  aspects   of  these
 treatment  operations  are  the high pH of waste  entering the aeration
 m^iL-jan^   •  e 4.l!19h  mixed   1:L<3uor  suspended  solids  concentration
 maintained   in   the aeration  basin.   In many cases, a pH above  11  0  is
 seen^as potentially toxic  to   biological   activity.'   Eowev^r?   carbon
tbou         rVrrnSm "-Pi"^-  is  adequte touce the  pH
to  about  8.0, at which point biological  stabilization  occurs    Since
primary clarification is not provided, all  suspended  solids   in thl
^o?er^ Waf 6  9° directly to the aeration basin.  All  solids  captur
must, therefore, occur in the final  clarifier.   The  most   important
fact  to note is that from the start of operation, the tre^tmen? plant
"af overloaded compared to the design of the  system.    Further  some
difficulty  in  solids capture in the final cl Jifier was^xplrienced
In spite of the very high  effluent  concentrations,  variability  and
upsets were not related to winter conditions.            t^inty  ana

Removals  of  89  percent for BOD5 and 90 percent for suspended solids
were observed during a sampling visit for toxic  pollutants  at plant
no.  320.   However  at the time samples were taken the  skimmer in the
clarifier was not working properly and was by actually stirring ^p the
water, it was decreasing  the  removal  efficiency.   Furthermore   no

                                                 '
                                  "~
                                 172

-------
A related biological treatment technology is the oxidation ditch.  The
oxidation ditch is essentially a modified form of the activated sludge
system.  Applications of this process on domestic waste treatment  are
numerous   in   Europe.   A  full-scale  installation  at  Oisterwijk,
Netherlands, has successfully  treated  chrome  tannery  wastes  since
1973.   This  system  is  called  the  Carrousel  system.   In tannery
treatment, the wastes were directed to an oval ditch or  "race  track"
for  aeration.   Separate  equalization  facilities  were not required
since  the  ditch  provides  excellent  equalization.   An  adjustable
immersion  dish  aerator operates in a localized and limited volume of
the channel and imparts oxygen to the  wastewater  and  regulates  the
velocity  of  flow in the channel.  The effluent is clarified prior to
discharge with  the  sludge  returning  to  the  aeration  zone.   The
oxidation  ditch  operates  in  the  extended  aeration  mode  (one day
hydraulic detention or greater) and at high mixed liquor solids.   The
resulting food-to-microorganism  (F/M) ratio is very low.  At these low
F/M   ratios  (0.05),  long  detention  time,  and  high  sludge  age,
endogenous respiration minimizes the amount of waste sludge.

Data for the first year operation of the Carrousel system  on  leather
tanning  waste  at  a  hydraulic  load of 1800 m3/day is summarized in
Table 29.

                               Table 29

     Carrousel System Performance for Leather Tanning Wastewater
Pollutant
Parameter
BODS
COD
Cr
Total N
NH4-N
Raw Secondary Effluent
1100
3390
19.5
408
264
20
249
0.27
270
248
Percent
Removal
98
93
99
34
5
This fully-operational European Carrousel treated the flow from a side
leather tannery using 25,060 kg per day of green-salted hides   (55,200
Ib/day).   The  tanning  process  produced  1800 m3/day  (0.475 mgd) of
wastewater from pulp  hair,  chrome  tan,  and  finishing  operations.
Hydraulic  detention  time  in  the oxidation ditch varied from 2 to  3
days, and the rate of activated sludge  return  was  estimated  at  75
percent.   Production  of  secondary  sludge was about 0.3 kg  (Ib) dry
solids per kg  (Ib) BOD^ applied, or 0.55 kg  (Ib)  dry  solids  per  kg
(lb)  BODJ5  without  primary  sedimentation.   The organic load on the
ditch varied from 23.5 to 48.2 kg BODJ5 per day  (51.8 to 106.2 lb  BOD_5
per  day).   The  oxygen  supplied  was  about  1.75 times the average
requirement, however.  This was sufficient  for  peak  demands.   High
removals  of  BODj>  (98 percent) and COD  (88 percent) result at the low
F/M ratio.


                                 173

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 Sulfides were completely  oxidized  with  the  aeration  supplied  and
 chrome precipitation was highly effective, with concentrations below 1
 mg/1  observed in the effluent.  Nitrification was sporadic, with some
 denitrification through the liberation of nitrogen gas.

 High removals of BOD, COD, suspended solids, chromium  and  detergents
 resulted  from  the operation of the Carrousel tannery waste treatment
 facility.  Efficiency did not decrease during the winter months.

 This same system was recently installed at a  shearling  tannery  (no.
 253) in New England.  This Carrousel system treats 300,000 gallons per
 day  of  primary  effluent.   During  a very cold period (even for New
 England)  from December 1976 through February  1977,  average  influent
 and   effluent   BODS   concentrations  were  341  mg/1  and  8  mq/l
 respectively.  Ammonia concentrations in  the  influent  and  effluent
 were  32  mg/1  and  8  mg/1,  respectively.  This indicates that this
 activated sludge system produced better results than  the  Netherlands
 application,   including  demonstration  of  nonsensitivity  to  winter
 temperatures   in  removing  carbonaceous  oxygen  demand  (BODS)    and
 nitrogenous  oxygen  demand  (ammonia)  by nitrification.   This'svstem,
 like the activated sludge system at tannery no. 320,  operated at   hiqh
 mixed liquor  suspended solids (6,000 - 15,000 mg/1).

 These  results have been further corroborated by a POTW in New England
 treating greater than 90 percent of its waste load  from  tannery no
 ^!Z   J   ^ .POT*! 1S a high rate (F/M 9reater than 0.1)  short hydraulic
 detention time (approx.  12 hrs.)  activated sludge system.   During the
 first year of operation  (1976),  final  effluent quality was  poor due an
 extended   acclimation period  and   to  lack  of   familiarity with the
 operational idiocyncracies  of the plant.   After operational procedures
 were refined,  effluent BODS concentrations improved dramatically,  from
 an average range  of 102-393 mg/1 to a  range of 49-67   mg/1.    in   fact
 during  the very  cold winter months  of  1976-1977,  effluent BODS  quality
 improved  to 34 to 45  mg/1,   since that  time tannery flow has  increased
 o^r^?™  ^• f n des^ limits for extended periods  of  time,  but better
 operating  skills   have  maintained  average BODS effluent quality  below
 80 mg/1.   Therefore,  the basic  feasibility  of  the  activated  sludqe
 demonstrated.  ^   imp°rtanCe  °f   dili*ent  operation  have blen lirmly

 Activated sludge systems, including various modifications,  have  been
 and  can be effective  in organic reductions to low BODS  concentrations
 even  under  low temperature conditions.   Removals of'suspended solids
 prior to final effluent discharge and maintenance of a large  Juantity
 of   active  biomass   in  the  aeration basin, especially during winter
 montns to compensate  for lower rates of organism activity,  appear  to
 fina?c!ar!rLr?n  COnservative  design  *nd diligent operation of the

Based on the discussion above, treatment of process wastewaters  by  a
high  solids,   low  F/M,   extended aeration activated sludge system is
                                 174

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appropriate for the leather  tanning  industry.   The  performance  of
primary   coagulation-sedimentation   followed   by  activated  sludge
biological treatment has been established primarily by plant  no.  47,
as  noted  in  Section IX of this document.  The long-term performance
(annual average)  for this plant is BOD5 - 60 mg/1, and TSS - 95  mg/1.
With the addition of in-plant control and preliminary treatment  (i.e.,
chromium  recovery, ammonia substitution, catalytic sulfide oxidation,
flue gas carbonation of segregated beamhouse  wastewaters,  and  water
conservation/reuse),   the   Agency   believes   that  this  long-term
performance is improved primarily due to  longer  hydraulic  detention
times  and reduced pollutant loads.  Additional rationale is presented
in Section X.  The Agency has conservatively estimated the  achievable
long-term   concentrations   in   the  effluent  from  this  secondary
biological process as follows:  BOD5 - UO mg/1; TSS - 60  mg/1;  total
chromium  - 1 mg/1; oil and grease - 14 mg/1; TKN - 30 mg/1; ammonia -
10 mg/1; and phenol  -  0.25  mg/1.   For  residual  COD  an  effluent
concentration  of  250 mg/1 was determined from a ratio of COD to BODJ5
developed from biological treatment data during an EPA  study.71  This
relationship  is displayed in Figure 3.  For BODj> concentrations below
160 mg/1 the  plot  approximates  a  straight  line.   Achievable  COD
concentrations   for   technologies   which   generate  effluent  BOD5
concentrations below this value have been determined  using  the  BODj>
concentration and Figure 3.

Rotating  Biological  Contactor.   The  rotating  biological contactor
(RBC) consists of a series of closely spaced flat parallel disks which
are rotated while partially immersed in wastewaters being treated.   A
biological  growth  covering the surface of the disk adsorbs dissolved
organic matter present in the wastewater.  As the biomass on the  disk
builds  up,  excess  slime is sloughed off periodically and is settled
out in sedimentation tanks.  The rotation of the disk carries  a  thin
film  of wastewater into the air where it adsorbs the oxygen necessary
for the aerobic biological activity of the biomass.  The disk rotation
also promotes thorough mixing and contact between the biomass and  the
wastewaters.   In  many  ways the RBC system is a compact version of a
trickling filter.  In the trickling filter, the wastewaters flow  over
the  media  and  thus over the microbial flora; in the RBC system, the
flora is passed through the wastewater.

The system can be  staged to  enhance  overall  waste  load  reduction.
Organisms  on the  disks selectively develop in each stage and are thus
particularly adapted to the composition of the waste  in  that   stage.
The  first  stages  might  be  used  for  removal of dissolved organic
matter, while the  latter stages might be adapted to  nitrification  of
ammonia.

The  RBC  system  was developed independently  in Europe and the  United
States about 1955  for the  treatment  of  domestic  waste,  but  found
application  only  in  Europe,  where  there   are  an  estimated 1,000
domestic installations.72 The use of the  RBC  for  the  treatment  of
industrial wastes  in the U.S. has been under evaluation for some time.


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Bench  scale  tests have been made on tannery wastewater.  Other pilot
scale  results  on  meat  packing  waste  showed   a   BOD5   effluent
concentration of approximately 25 mg/1.73

Data from one of the suppliers of RBC systems indicate ammonia removal
of  greater  than  90 percent by nitrification in a multistage unit.73
Four to eight disk  stages  with  maximum  hydraulic  loadings  of  61
1/day/m2  (1.5 gpd/ft2) of disk area are considered normal for ammonia
removal with final ammonia  concentrations  as  low  as  2.0  mg/1  or
less.74

Rotating biological contactors with secondary clarifiers could be used
as  a  substitute  for an entire aerobic system.  The number of stages
required depend on the desired degree of treatment  and  the  influent
strength.   More  typical  applications  of  the  rotating  biological
contactors,  however, may be for polishing the effluent from biological
processes, nitrification of effluents, and as  pretreatment  prior  to
discharging  wastes  to  a  municipal  system.  A BOD5 reduction of 98
percent is reportedly achievable with a four-stage RBC.72

The major advantages of the RBC system, as indicated by the  suppliers
of  this  equipment, are its relatively low first cost; the ability to
stage to achieve dissolved organic matter reduction with the potential
for removal  of  ammonia  by  nitrification;  and  its  resistance  to
hydraulic  shock  loads.   Disadvantages are that the system should be
housed in cold climates to maintain high removal efficiencies  and  to
control  odors.   Although this system has demonstrated its durability
and reliability for domestic wastes in  Europe,  its  use  on  several
industrial  wastes in the United States has not yet established a high
degree of confidence in this technology.73

Nitrogen Control.  Nitrogen control is provided through the process of
nitrification-denitrification, as described below.

     Nitrification.

Nitrification is the biological conversion of nitrogen in  organic  or
inorganic  compounds from a more reduced to a more oxidized state.   In
the  field  of  water  pollution  control,  nitrification  usually  is
referred  to  as  the  process  in  which  ammonia  as ammonium ion is
oxidized to nitrite and nitrate sequentially.  When  aeration  systems
are  used to treat an industrial wastewater, some nitrification can be
expected to occur naturally, thus reducing  the  quantity  of  ammonia
requiring further removal.

Adequate  process  design  and  operating  control  are  necessary for
consistent results.  Factors that  affect  the  nitrification  process
include   concentration  of  nitrifying  organisms,  temperature,   pH,
detention time, dissolved oxygen concentration, and the  concentration
of any inhibiting compounds.74
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 Nitrifying  organisms  are  aerobic  and  adequate  dissolved  oxygen  (DO)  in
 the  aeration  system is necessary.   DO concentrations  should  be  above 1
 to  2   mg/1  to   assure   consistent  nitrification.   Nitrification  is
 affected  by the  temperature   of   the   system.   Available  information
 provides    conflicting    data on  the  systems1  performance   at  low
 temperatures.  Although detailed   studies  are lacking,it   should   be
 possible  to   achieve nitrification at low temperatures  and  compensate
 for  slower  nitrifying organism growth rates by maintaining  a   longer
 solids  detention  time and  hence larger nitrifying active mass in the
 system.76

 The  optimum pH for  nitrification  of  municipal sewage   has  been  set
 between   7.5  and 8.5.  Nitrification  can proceed at low  pH levels, but
 at less than  optimum  rates.   During nitrification, hydrogen  ions  are
 produced  and the  pH  decreases,  the magnitude of the  decrease being
 related to  the buffering  capacity of  the system.

 The  removal of nitrogen compounds   from a  tannery   waste   stream   is
 important  because  these compounds:   exhibit  an oxygen  demand  similar
 to that of  BOD;  provide nutrients  for plant organisms in the receiving
 water  body,   increasing  eutrophication rates;  and  may   present   a
 significant hazard  to aquatic organisms.

 Biological  oxidation of organic  and ammonia  nitrogen to nitrites and
 nitrates  is accomplished  by  only   two  bacteria  types,  nitrosomonas,
 which   convert   ammonia   and  organic nitrogen  to   nitrites,  and
 nitrobacter,   which  convert nitrites   to   nitrates.    The   growth
 conditions    necessary    for  these    bacteria  can  be  supplied   by
 conventional   secondary   activated  sludge  systems,  although  longer
 detention times  are  required,  generally resulting  in  larger  systems
 for  BOD control,  especially  at low  operating temperatures.

 Very little data  exists on nitrification toxicity  effects.   Sulfides
 under BPT conditions  should  be reduced  to a concentration of 1  mg/1,  a
 level  below   concern for either nitrifying bacteria.   Chromium, which
 is reduced to  a  level of  2 mg/1 after  chromium recovery  and  combined
 primary   treatment,  is   of  potential  concern  since one source77 lists
 chromium  toxicity at levels  of 0.25 mg/1.  While actual test  data   is
 limited,  the  acclimatization of organisms should tend to mitigate any
 problem with chrome toxicity.  Removal of phenol and other potentially
 toxic organic chemicals in the primary and first stage along with  the
 acclimatization  of  the  organisms of activated sludge to the tannery
 wastes should permit effective nitrification.

 Nitrification rates are reported to be dependent on temperature.   One
 reference7®   states   that   proper   nitrification  occurs   only  at
 temperatures of at least 12 to 15°C.  One  successful   application  of
nitrification  has  been  demonstrated  at  a rendering plant in Ohio.
 This  is  a  conventional  activated  sludge   system  which  uses  two
 consecutive  aeration  tanks in series prior  to secondary clarificatin
and multi-media filtration.   The system operates at a   temperature  of


                                 178

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at  least 55°F (12.8°C) even on the coldest days by virtue of the high
raw wastewater discharge temperature  associated  with  the  rendering
process,  estimated  at  90°F   (32°C);  and on extremely cold days, by
covering the tops  of  the  aeration  tanks  with  boards.   Tanneries
discharge  raw wastewater at temperatures approximating 70°F (21°C) in
winter, and thus the expectation would be that lower temperatures  may
occur  in  a  tannery  nitrification  system.   Heat  addition is also
possible as an alternative but would increase operating expense unless
waste heat recovery  (such as stack  gas  heat)   were  employed.   Only
during  the  coldest time of the year in the northern locations should
temperature maintenance be of concern.

To operate successfully,  nitrifying  bacteria  must  have  proper  pH
conditions  (7.5  to  8.2)  and nutrients (such as calcium, magnesium,
phosphorus, copper, and iron).78 These requirements, if not present in
tannery wastewaters, will have to be provided  by  chemical  addition.
Only  pH control and phosphorus addition are expected to be needed for
normal tannery wastewaters.

Physical-Chemical Processes - LEVEL 4 A

Chappel Process.   The Chappel process is a patented  physical-chemical
process  for  treating wastewater streams.  The basis for this process
is the assumption that all  waste  streams  contain  components  which
flocculate  or settle in the proper environment.  The process consists
of dividing the wastewater stream into two equal parts,  treating  one
part  with  the  acid  solution   (mineral acids, aluminum sulfate, and
oxidizing chemicals) and the other with the alkaline solution  (sodium
hydroxide,  forms of dissolved aluminum, and oxidizing chemicals), and
then reuniting the  divided  waste  streams.   Some  flocculation  and
solids  formation  takes place when the acid solution and the alkaline
solution are added  to  the  separated  parts  of  the  waste  stream.
Additional  flocculation and solids formation takes place when the two
parts of the wastewater stream are reunited.  The reunited  wastewater
stream  flows  into  a  series  of  two  or  more settling tanks.   The
wastewater and sludge entering each of the tanks is initially agitated
and allowed to settle.  Supernatant and  sludge  are  pumped  counter-
current  through the series of settling tanks.   Agitation in each tank
mixes settled sludge with the wastewater.  According to  Chappel,   the
sludge  aids  the  flocculation  and  settling  of  pollutants  in the
wastewater stream.  The wastewater stream from the final settling tank
is passed through a sand or multi-media filter and discharged  to  the
receiving  waters.  Some of the sludge from the first settling tank is
recycled to aid flocculation and sedimentation and  the  remainder  is
removed  for  disposal.  It has been indicated that this sludge has no
oxygen demand and is sterile; however, it may require dewatering,

The Chappel process was used to treat less than  100,000  gallons  per
day   of  wastewater  from  a  retan  facility  (no.  247).   In  this
installation,  there were nine settling tanks  (existing  idle  tankage
used in part), and only 25 percent of the effluent is passed through a


                                 179

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           *4
rudimentary* sand  filter.   The  other  75  percent  is  discharged directly
to the receiving river.    It  is  particularly   noteworthy  that   this
system  was  housed within the  tannery itself.   This  is  very important
to  plants  which  have  very   limited   adjacent land   available  for
installation of equipment.

The effluent quality  from  this  installation  far  surpassed  state permit
requirements.  This process is  highly effective  in  removing  pollutants
from  tannery no.  247 wastewater, as  shown in Table 30.  It  is obvious
that  this  application  of physical-chemical   treatment  was  highly
effective  in removing toxic pollutants  (see also Table  36,  Section X)
including chromium, and conventional  and nonconventional pollutants.

                                Table  30

             Treatment of  Wastewater  with Chappel Process
                           at Tannery  No. 247
Pollutant
Parameter
BOD5
COD
TSS
TKN
NH3
OSG
cr
Typical Influent
Value (mg/1)
700 -
1200 -
300 -
120 -
60-1
110 -
16
800
2700
800
270
60
280

Typical Effluent
Value (ma/11
3 -
20 -
6 -
3 -
1 -
4 -
less
10
40
11
6
3
9
than 0.1
Process effectiveness has been tested in treating tannery wastes  from
three other tanneries.  Results are summarized in Table 31.
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                               Table 31

         Performance Summary of the Chappel Process Treating
                         Tannery Wastewaters


Pollutant           Influent Value      Effluent Value
Parameter	(mg/1)	(mq/1)	

Tannery No. 57
     BOD5                 1800                5-70
     Sulfide              70                  0. 1

Tannery No. 409
     Chromium             20                  0.1
     Sulfide              1.8                 0

Tannery No. 213
     Chromium             40                  0.1
     Sulfide	1	0.2	

Wastewaters  with significantly higher BOD5 may require a modification
of the  process  to  obtain  effective  treatment.   The  modification
consists  of  operating  two  systems in series; the first removes the
bulk of the pollutants, while the second  "polishes"  the  wastewater.
This  process is also being used to treat a paper mill waste, although
data is not currently available.

On a long-term basis, the Agency conservatively  estimates  that  this
physical-chemical  treatment  system  will  produce  the same effluent
concentrations as can be produced by a  PAC  upgraded   (Level  5}  and
multi-media  filtered   (Level  6)  activated  sludge system.  Both the
physical-chemical   (Level  4A)   and  biological  treatment   (Level  4)
systems  are  preceded  by  in-plant  control   (Level  1), preliminary
treatment  (Level 2), and  primary  treatment   (Level  3),  which  will
produce  pretreated  effluent  concentrations similar to or lower than
those listed in Table 30 as "Typical Influent" at plant no. 247.   The
long-term   treated   effluent  performance   (concentrations-mg/1)  is
conservatively estimated by EPA to be somewhat higher than represented
in Table 30 because the available data from plant no. 247 was not  for
a  sufficient  length  of  time to estimate effluent variability.  The
estimated concentrations are as follows: BOD_5 -  14  mg/1;  TSS  -  16
mg/1;  COD  - 180 mg/1; oil and grease - 6 mg/1; total chromium - 0.33
mg/1; TKN - 15 mg/1; ammonia - 5 mg/1; and phenol - 0.1 mg/1.

Color Removal.  Vegetable extracts and syntans used in the  production
of leather comprise only a small percentage of the total waste volume,
however,  spent  vegetable  tanning  solution can be responsible for  a
major portion of the organic content and most of the color agents in  a
total wastewater discharge.
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 Several factors relating to the chemical structure of the color agents
 were considered significant in efforts to reduce color by Nemerow. *«

 Tomlinson,  et.  al.«o conducted laboratory investigations  with  mimosa
 (wattle)  extract  with  lesser amounts of quebracho and chestnut bark
 extracts.   Two  commercial syntans,  Orotan TV (a phenolic  syntan)   and
 Leukanol  D-48   (an acid or naphthalene syntan), were also used in the
 blend.  A small amount of sodium bisulfite was  added to accelerate the
 adsorption   of   tannin  by  the  hide  protein   collagen.    These  six
 ingredients,  mixed  in the proper  proportions  with water amounting to
 about 75 percent of the total weight  of the solution, constituted  the
 stock tanning solution.

 During the   course  of  the  investigations,   the following treatment
 techniques  for  the  removal of color  were  evaluated:  oxidation  with
 sodium hypochlorite,  use of lime or alum,  and coagulation with organic
 polymers.

 Color  removal   from  the vegetable  tanning solution was achieved under
 the  treatment conditions developed  in the course of the research   The
 treatment scheme, as  described in Tomlinson and  applied to  an  actual
 tannery, would  involve the following  sequential  steps:

      1.   Segregation of the spent  vegetable tanning liquor.

      2.   Addition  of sulfuric acid to  reduce the  pH of  the   solution
          below  3.0.

      3.   Addition  of a  predetermined dosage of  a  preselected  cationic
          organic polyelectrolyte and,  at   the   same  time,  continued
          addition  of sulfuric  acid to  maintain  the  pH below 3.0.

      4.   Slow mixing to  provide sufficient contact time   for  maximum
          color  removal.

      5.   Sedimentation  for  approximately  30 minutes.

      6.   Decantation of the treated supernatant, at a regulated rate,
          to the remainder of the waste  flow  from  the  tannery  for
          further treatment, if needed.

     7.   Withdrawal  of  the  sludge   for  further   dewatering,   if
          required,  and disposal.

Tomlinson summarizes his study as follows:

     "A  commercially available cationic polymer was used successfully
     for color removal in the research.  The optimum dosage was on the
     order of 30 mg/1.  (This procedure  resulted  in  a  reduction  in
     color   of  more  than 90 percent).  Concurrent with the excellent
                                 182

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     color removal,  significant reductions were observed  in  the  COD
     (50 to 60 percent)  and suspended solids (85 to 90 percent).

     "Sludge  amounting  to  approximately  30  percent of the original
     volume of the tanning solution is produced as  a  result  of  the
     need to remove the color and reduce the other pollutants.   It was
     shown in this research that the sludge resulting from coagulation
     at  a  pH  of  approximately  2.5  to  3.0 settled better and had
     greatly improved dewatering characteristics compared with sludges
     resulting from treatment at higher pH levels.

     "The economic feasibility (of this technology)   would  depend  on
     the  characteristics of the waste, the effluent requirements, and
     the cost of achieving them by other methods.  For  a  given  real
     situation, complete laboratory studies would have to be made with
     various   polyelectrolytes   to   determine  the  combination  of
     polyelectrolyte, dosage, pH, mixing time,  flocculation  time  and
     settling  time  that  would  produce the desired results at least
     cost.  Because characteristics of tanning solutions vary,  it  is
     to  be  expected  that  optimum treatment combinations would also
     vary."

Upgrading Biological Treatment with Activated Carbon - LEVEL 5

The use of activated carbon in  treating  industrial  wastewaters  has
been  generally successful depending on the application, the soundness
of engineering, the degree of proper operation  and  maintenance,  and
the  performance  criteria  established  for the system.  According to
Cheremisinoff81 "adsorption studies indicate that  most  of  the  EPA-
proposed  dissolved  organic  toxic  chemicals can be removed from the
water by activated carbon  (and) other  similar  chemical  contaminants
(aromatic,  nonpolar,  high  molecular  weight),  such as OSHA-defined
carcinogens and the chemicals under examination by EPA  for  inclusion
on  the  toxic substances list are also predicted to be adsorable from
wastewater by activated carbon."

Cheremisinoff explains further:

     "Adsorption makes possible the purification of wastewater streams
     containing  only  small  amounts  of  impurities  that  would  be
     difficult  to  clean  by  other  means and at an attainable cost.
     Carbon is the most versatile of the solid  adsorbents  and  finds
     the  widest  application in both air and water pollution control.
     The use of activated carbon for removal of organic compounds from
     air and water streams has a long history of successful use, being
     one of the most efficient organic removal processes available.

     "The ability of activated carbon to adsorb material  either  from
     gases  or  from  liquids  stems from its highly porous structure.
     Each particle consists of a vast network of interconnecting pores
     of a variety of sizes.  The highly porous structure results in  a


                                 183

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 very   large  surface  area,  providing  many  sites  upon  which
 adsorption of molecules can take place.  Normally, adsorption  on
 activated   carbon  is  the  result  of  physical  attraction  of
 molecules to the carbon surface by van der Waals  forces.   As  a
 rule,  molecules with higher molecular weights experience greater
 forces of attraction than materials of lower  molecular  weights
 Hence,  activated  carbons,  aside  from the effects of molecular
 screening due to the sizes of the pores, have  a  preference  for
 higher molecular weight substances.

 "When  a  granule of activated carbon is placed in contact with a
 mixture of gases, the higher molecular weights are preferentially
 attracted to the carbon where they are adsorbed.   when a  granule
 of  activated  carbon is placed in contact with a liquid mixture,
 there  is  a  similar  tendency  for  higher   molecular   weight
 substances  to  be  adsorbed.   However, in the liquid systems the
 situation is more  complicated.    In  liquid  systems,  activated
 carbon  tends  to have a preference not only for  substances which
 are of higher molecular weight but also for those substances that
 are non-polar in nature.   Thus,  there is  a  particular  affinity
 for  the  adsorption  of  non-polar  organic molecules from polar
 solvents such as water.                                      f^iaj.

 "The forces   of   attraction  between  the  carbon  and  adsorbate
 molecules are  greater  for adsorbate molecules which are similar
 in size to the carbon  pores.   The  most tenacious  adsorption takes
 ^oCexW!?en th?  P?reS  are  barely  l^ge  enough  to  admit  the
 adsorbate molecules.    The smaller the pores  with respect to  the
 molecules, the greater the  forces  of  attraction.    The  pores
 cannot be so  small,  however, that  the  adsorbate molecules find it
 difficult  to  enter,  or  the  adsorptive  capacity  for  those
 molecules will be greatly  reduced.   Although the  effects  are  not
 completely understood, it is known that  the presence of  elements
 other  than carbon can  have a considerable influence on a  carbon's
 adsorptive capabilities.   Particularly  important  is oxygen,  which
 can  exist  in a variety of  chemically combined conditions  with  the
 surface carbon atoms.  These oxygen  groups appear  to  increase  the
 affinity  of the  carbon  for  polar   compounds  and decrease  its
 selectivity for  non-polar  compounds.

 "Carbon   adsorption  systems  are   of  two types-regenerative and
 nonregenerative.   For   operations   in   which   daily   carbon
 requirements  are  large  or under constant use, granular carbons
 offer the advantage of established methods of regeneration  which
 greatly  reduce carbon replacement costs.  Powdered carbons offer
mfvanno?eh ^ aPPlicat^ns where the  daily  carbon  requirements
may  not be large enough to warrant installation and operation of
snPMf?/^ener^1Ve equi?ment-  Jt is also  possible  that  some
specific adsorptive capacity may be available in certain types of
powdered carbon."si                                       ^yy** or
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Powdered carbon is mixed directly with the liquid to be treated.   This
•slurry1 is then agitated to allow proper contact.  Finally,  the  spent
carbon,  carrying the adsorbed impurities, is filtered or settled out.
In practice, a multiple-stage,  counter-current  process  is   commonly
used to make the most efficient use of the carbon«s capacity.

A  relatively  new  application  of powdered activated carbon (PAC)  is
being tested and  evaluated  in  combined  carbon-biological   systems,
because  of the ability of activated carbon to improve the performance
of biological systems.   This  concept  is  now  undergoing  extensive
testing, using powdered carbon material in activated sludge systems.82
The  carbon  is  metered  into  the  system  with  the  influent   at a
concentration normally less than 100 mg/1.   It  is  recirculated  and
purged  along  with the biological solids at a rate which maintains an
equilibrium concentration  of  1000-2000  mg/1.   Since  the   powdered
carbon  is  added  directly  to  the  activated  sludge  process, this
eliminates the need for carbon-adsorption beds or columns.

Powdered carbon may provide some of the following benefits when  added
to activated sludge systems:

     1.   improved toxic pollutant removals;

     2.   improved organic pollutant removals, including BOD, COD, and
          TOC;

     3.   more uniform operation and  effluent  quality,  particularly
          during  periods  of  widely  varying  organic  and hydraulic
          loads;

     4.   decreased effluent solids and thicker sludges  resulting  in
          reduced sludge handling costs;

     5.   adsorption of organics, such as detergents,  oils  and  dyes
          that are refractory to the biological system;

     6.   protection  of  the  biological  system  from  toxic   waste
          components;

     7.   more effective removal of phosphorus and nitrogen;

     8.   increased  effective  plant  capacity  at    little   or   no
          additional capital  investment;

     9.   savings on operating costs resulting from reduced  defoamer,
          coagulant and power requirements;  and

     10.  greater  treatment  flexibility than  other methods  since
          carbon  dosages   can  be varied to match waste strengths and
          flow rates.
                                  185

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Powdered carbon improves treatment in  the  activated  sludge  process
because of its adsorptive and physical properties.  Carbon adsorbs the
pollutants  and oxygen, localizing them for bacterial attack.  Because
reac^n? blc"ac^°" . i?  dependent  upon  the  concentration  of  thl
reactant,  this localizing effect serves to drive the reaction further
towards  completion,  resulting  in  improved  BOD   removal, a a  "any
pollutants  that  are  not  biologically  degraded  in  a conventional

   11  9e    tem W°U1<  be degrad*d if the* we« i* Sntlct wi?h
 theMos                                    e* we«      ntct wi
 the biomass for a longer period of time,  when adsorbed by the carbon
 these molecules settle into  the  sludge.   Contact  time  is  ther^b
 extended  from  hours to days.   This results in lower effluent COD and


 High density powdered carbons  improve  solids  removal  in  secondary
 clarifiers.   This results in lower effluent suspended solids and also
 wou?dU?LT/n ?°2-  ^ hlgh °rganiC load Conditions which normalfy
 would lead to sludge bulking, the dense carbon will act as a weighting
 agent keeping the sludge in the system.  A doubling of  sludge  voluml
 BothXe?he" nlf ^f wherVarb°? addition is practiced is not^ncommon?
 Both  the  use  of  greater  sludge mass and the extended retention of
 slowly degraded compounds  by  the  carbon  give  more  time  for  the
 compound  to  be  biologically   stabilized.   when  dispersed  Mofloc
 results due to low organic loads,   carbon serves as a  seed  for  floe
 formation,    preventing   loss    of  solids  under  these  conditions
 Phosphorus  and nitrogen removals are reportedly enhanced.

 Powdered carbon can be  added at any convenient point in the  activated
 sludge  process  to  get  it into  the  reaction  section,   it is not
 necessary to add carbon continuously in most cases.   Batch addition at
 any  time of day is generally satisfactory.    A  dense,   easily  we?ted
 carbon  can  be  added   dry or  slurried with water,   in fart,  the very
 nature of  the  slurried  carbon  in  a  solution  provides   extremely
 ^T   Ka?d  thorou|h  contact  between the carbon particlefand the
 solution being treated-more so than with granular   carbon  treatment
 Chemical coagulants  can  be  added  along with the carton  to prS;
 simultaneous  removal  of colloidal  organics.                     provide

 The  effectiveness  of   powdered carbon  as   an   additive  to   improve
 activated   sludge  treatment  has  been  demonstrated   in  a  variety of
 industrial  applications   and   at  POTWs.    These  improved  operatina
 properties  of   activated  sludge as  demonstrated in  oiher  application!
 covers wastewaters with similar characteristics.   For  example    both
 leather  tanning  and  petroleum  refining  wastewaters IrTpr^rea?ed
 prior to biological treatment and PAC addition.  Pretreated wastewater
 in both  industries also contain toxic pollutants.   Therefore    i*  T«
EPA- s  belief  that  PAC addition is tLnsferabt; becaulf of tte exact
duplication  of  the  technology  as  used  in  other  industries   to

teSogyVa'lso "ansfera^ej  "*  *»*.«»  "«*«—  "? this
                                 186

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This type of treatment has gained acceptance in the  last  tour  years
and  is  currently  an essential part of treatment at 60 to 80 plants.
These plants range in size from 10,000-gpd package units located along
the Alaska pipeline to a fully integrated  40-mgd  powdered  activated
carbon treatment system (PACT).84

The  PACT process involves a continuous addition of powdered activated
carbon to the aeration tank.  Buildup in the aeration tank  occurs  (a
function  of  the  sludge  retention  time),  providing  a substantial
reservoir of carbon in the system.  The continuous addition  of  fresh
carbon to the aeration tank allows the process to adsorb nonbiological
organic  matter present in the wastewaters, thereby providing a degree
of advanced treatment concomitant with normal secondary treatment.   A
recent  study85  indicated  that powdered activated carbon addition to
activated sludge systems provides  exceptional  resistance  to  shock-
loading  by  trichlorophenol, presumably due to the large reservoir of
carbon carried in the MLSS-  Trichlorophenols occur  in  most  tannery
wastewaters  at  concentrations  ranging up to about 10 ppm in the raw
wastewater.   A  study86  completed  on  organic-chemical   wastewater
indicated   that  the  PACT  system  was  economically, preferable  in
achieving the desired  effluent  quality  to  columnar,  granular  and
activated-carbon  systems,  both  preceding  and  following  activated
sludge.

Data pertaining to  effectiveness  of  the  PAC  treatment  system  in
removing  toxic pollutants indicates good performance for many organic
constituents.  Removal in excess of 95 percent for  total  phenol  was
observed   through   the   treatment  system,  producing  an  effluent
concentration of less than 0.02 mg/1.87

The addition of PAC to an activated sludge system was investigated  on
a   pilot  scale  to  improve  the  treatment  of  petroleum  refinery
wastewater.  It was found that "effective removal of oil and colloidal
solids  in  the  pretreatment  step  is   necessary   for   successful
operation." In addition, cost effectiveness was achieved by "operating
at  a  very  high sludge age and a low carbon dose." The higher sludge
age did not result in the deterioration of  settling  characteristics.
A  decrease  in effluent variability was noted which was attributed to
enhanced nitrification at low temperatures and  dampening  effects  of
increased  hydraulic  loading  to  the  activated  sludge  plant.   In
addition to effective removal of  ammonia   (less  than  1  mg/1),  PAC
addition  was  responsible   for  reductions  of 65 percent for soluble
organic  carbon  and  95  percent  for  phenolics  with   a   residual
concentration of less than 0.02 mg/1.86

A similar study was conducted by another refinery which was interested
in improving conventional activated sludge systems.  Accomplished with
pilot  plant units, increased sludge age  (from 10 to about 50 days) in
combination with powdered carbon addition was found to be a  potential
alternative  to installing costly granular activated carbon columns to
treat  secondary effluent.  With good pretreatment, upgraded  activated


                                  187

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 sludge  proved  effective  in  reducing  ammonia,  oil and grease, and
 phenols to  median  levels  of  less  than  4.0,  5.0  and  0.1  mq/1
 respectively.ee                                                  liy-«-r

 In  the  poultry processing industry, addition of powdered carbon at a
 southern commercial poultry processing plant improved effluent quality
 and process control. so A  full-scale  evaluation  of  powdered  carbon
 treatment  began  in August 1974.  In this plant, two activated sludge
 units treat an average of 400,000 gallons  during  a  10-hour  working
 day.   The  poultry waste passes through air flotation treatment prior
 to  activated  sludge  treatment.   Polymer  is  continuously  fed  to
 secondary  clarifiers  to  improve solids settling.   Sludge solids are
 removed periodically (every 3-4 weeks)  and transported to drying beds.

 The variable flow in this system, attributable  to  normal  processing
 operations,   caused frequent sludge bulking, high effluent solids, and
 variable effluent quality prior to use of powdered  activated  carbon
 Three  aerobic  lagoons  were  required  for  further organic removal!
 Prior to carbon addition, the activated sludge  effluent  averaged  35
 ppm  suspended  solids,  70  ppm  oil,  7 ppm BOD5, and 24 ppm ammonia-
 nitrogen «

 During the monitored period,  influent to the activated  sludge  system
 averaged  254   ppm  BOD5,  95  ppm  oil, and 129 ppm suspended solids.
 Dissolved  oxygen levels of 8-11 ppm were maintained  in  the  activated
 sludge  aeration  basins.   Powdered  carbon  was maintained  in  the
 aeration basins at an equilibrium  level  of  1,000-1,200  nom    Thic?
 required  a  daily  addition  of 10-15 ppm based on influent to" make up
  *!. £a^on  1°?*. 2U5"igJ  Sludge  wastin9-    After   carbon   addition,
variability diminished and  overall quality improved.  Average effluent
solids  decreased  60 percent to  12 ppm,  BOD5 decreased  57 percent  to  3
n^n^oeareaSed 1° Ve*cent to 21 PP1"'  *"d  nitrogen decreased 83
percent to 4>Ppm.  Assuming that the influent  analysis  made during the
control  period  is  typical  of normal  plant operation, the overall
                      "  percent:
The  basis for estimating the performance of activated sludge with PAC
addition started with the long-term performance of activated sludge as
previously described under "Secondary" Biological Treatment - Level 4
preceded by in-plant control  (Level 1) , preliminary  treatment~1Zevel
2),   and^  primary   treatment   (Level  3).   The  range  of  removal
efficiencies and final effluent concentrations after PAC  addition  in
the  above  referenced applications served to guide EPA's estimates of
removals in this case.  As summarized in Table 32, EPA estimates  that
±n?g™ally  S^lized  leather  tuning effluents can be upgraded by
about 50 percent for BOD and 60 percent for TSS.  This  nominal  level
was  chosen because the pilot and full scale studies were performed on
biologically stabilized  wastewater  in  other  industries  where  the
characteristics  of the tested effluent was similar to treated leather
tanning wastes .
                                 188

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PAC  upgraded  biological   treatment   will   yield   the   following
concentrations:  BOD5  -  20 mg/1, or approximately 50 percent removal
where 60 percent removal or more has been reported; TSS - 25 mg/1,  or
approximately   60   percent   removed   where  similar  removals  but
substantially lower effluent concentrations were achieved; COD  -  195
mg/1, as developed by the COD to BODjS relationship  (see Figure 3)  ; oil
and  grease  -  10  mg/1,  or  approximately  50 percent removal where
effluent concentrations as  low  as  5  mg/1  were  reported;  (total)
chromium  -  0.5  mg/1,  or approximately 50 percent removal estimated
somewhat less than TSS removal due to residual TSS and fine, insoluble
chromium which may carry over from secondary clarifiers; TKN - 20 mg/1
and ammonia - 5 mg/1, or  approximately  50  percent  reduction  where
greater  removals  and  effluent  concentrations as low as 4 mg/1 were
reported, and where nitrification without PAC addition  at  plant  no.
253   has   produced   ammonia  concentrations  very  close  to  these
concentrations; and phenol  -  0.1  mg/1,  which  is  a  concentration
achieved by this technology in the petroleum refining industry.

A  full-scale  demonstration  of  this  technology  is now underway at
tannery no. 253 and additional data will be reviewed by EPA-

                               Table 32

  Incremental Increase in Summary of Performance of Activated Sludge
          by Powdered Activated Carbon Addition 86  87 88 89
                 Demonstrated
                 Incremental                 Estimated
                 Increase in                 Increase in
                 Efficiency      Effluent    Efficiency    Estimated
Parameter          (percent)    Cone,  (mg/1)    (percent)    Cone,  (mg/1)

BOD5                 57            3              50            14

TSS                  60           12              60            16

Oil and Grease       70            5              50            6

Ammonia              83            4              50            5

Phenol               95          0.1              60          0.1
                                  189

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                                Table 33

           Summary of Multi-Media Filtration Performance
               Range of                           ~  "   ~~~~—	
              Incremental                Estimated
              Increase in                Increase in    Estimated
              Performance    Effluent    Performance    Effluent
 Parameter     (percent)     Cone,  (ma/1)  (percent)      Cone, (mg/11

 BOD1             50             6           30             14
 TSS            45 - 77          5           35
16
 Multi-Media Filtration - LEVEL £

 With the exception of gravity sedimentation,   deep-bed  filtration  is
 the most widely used unit process for liquid-solids separation.   Deep-
 bed filters have been employed in systems for phosphorous removal from
 secondary   effluents,    and  in  physical-chemical  systems  for  the
 treatment of raw wastewater.

 Filtration has been  applied  in  a  wide  variety  of  municipal  and
 industrial  applications.    In  most  cases,   filtration  is  used for
 nr^e1??*0*-??81?"*1  suspended solids afte* biological treatment. 103
 105 lie  119 Filtration  is  also  being  used  in  the  leather tanning
 industry  for separation of  residual biological and inert solids  which
 may include PAC with adsorbed toxic organic  compounds  and   insoluble
 heavy metals  such  as chromium.   Therefore,  EPA believes that multi-
 media filtration technology  is transferable,  and that  the same   range
 of  performance demonstrated  in other applications is also transferable
 to  the leather tanning  industry.

 Waste containing  suspended solids passes  through a filter  containing
 K^nUla£ ma^er1i?1 resulting  in the  capture  of  suspended  solids in the
 or  ;h. ^h6?Dually  the  pressure drop through the  bed becomes  excessive^
 or  the ability of the bed  to remove suspended  solids is  impaired.  The
 filtration cycle  ceases  and  the bed is  backwashed prior  to its  return
 to   service     in  an   ideal   filter, the size  of the  particles should
 decrease uniformly  in  the   direction   of   flow.    This   condition  t=
 partially  achieved  with  the   use  of a multimedia  deep bed fUter
 This  type of  filter  uses materials  with different   densities  ranging
 from  large size  particles with the  lowest densities at  the top of the

 the lilt- ^i^10163 Wlth the  highest densities  at  the bottom of
 the filter.  With this arrangement, the filter  has  a   large  storaae
 capacity  for  suspended solids, and is  able to remain in operation for
 long™/r^10dS ?5 5lme;  Influent soli3s should be  limited  to  about
 100 mg/1 to avoid too frequent backwashing.  Effluent suspended solids
are  normally  less  than  10  mg/1.us Filtration can also accomplish
removal of free oil, and to a limited degree,  emulsified  oil.   Where
                                 190

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concurrent removal of suspended solids is necessary, filtration can be
effective.

A  summary  of  the  typical  performance  of  several applications of
filtration  applied  on  activated  sludge  and   other   biologically
stabilized effluents is given in Table 33.  From these data, EPA finds
that  a reasonable estimate of achievable performance by filtration is
30 percent removal of  BODJ5  and  35  percent  removal  of  TSS.   For
purposes  of applying this technology to PAC upgraded effluent quality
(Level  5),  the  following  conservative  long-term  performance   is
achievable  with  multi-media  filtration of upgraded activated sludge
effluent: BOD5^ - 14 mg/1, or approximately 30 percent removal;  TSS
16 mg/1, or approximately 35 percent removal; oil and grease - 6 mg/1,
or approximately 40 percent removal.

A  lower  removal  efficiency  for  TSS  (35 percent) than noted in the
literature was considered appropriate because  of  the  low  operating
range  of  long  term  average effluent concentration in this industry
(less than 20 mg/1), and the very fine solids which must be separated.
A somewhat  lesser  efficiency  for  BODj>  removal  (30  percent)   was
conservatively  estimated  because  of  the  low  operating  range  of
concentration  (less than 20 mg/1) and for lack of more extensive data.
Oil and grease removal efficiency was estimated to be approximately 40
percent because residual oil and grease after biolgocial treatment  is
likely  to be associated with suspended solids, and thus removed at an
efficiency comparable to  TSS.   Other  effluent  concentrations  were
estimated  as follows: COD - 180 mg/1, as developed by the COD to BODJ5
relationship  (see Figure 3);  TKN  -  15  mg/1,  or  approximately  25
percent removal due to removal of residual insoluble proteinaceous TKN
with  TSS;  ammonia  -  5 mg/1, or no change since filtration does not
enhance nitrification;  (total) chromium - 0.33 mg/1, or  approximately
35  percent  removal  which  is the same as the anticipated removal of
TSS;  (total) phenol -0.1 mg/1, or no change since phenol  is  removed
by  biological  treatment and none occurs in filtration.  These values
were chosen as representative of the performance  to  be  expected  on
similar  biologically  stablized  leather tanning wastewater where the
residual biological solids, inert PAC particles and oil and grease are
amenable to physical separation.

Granular Activated Carbon Columns - LEVEL 2

The properties outlined during the discussion  of  powdered  activated
carbon  are also pertinent to granular activated carbon  (GAC).  Rather
than being mixed in a slurry, granular carbon is  packed  in  beds  or
columns.   The  water  to  be  treated is then either filtered down or
forced up through the beds.  In this manner, each successive layer  of
carbon acts to remove impurities, with maximum adsorption taking place
in  the  early stages of contact and less and less taking place as the
gradually  purified  solution  continues  on  until   (if  the  bed  is
sufficiently  deep) all adsorbable organic impurities are removed.  In


                                 191

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 some cases, suspended matter  (via filtration by the carbon) as well as
 dissolved pollutants (via adsorption) can be removed simultaneously. *i
 As noted by Cheremisinof f e i, carbon adsorption has  a  wide  range  of
 applicability to wastewaters with residual dissolved organic compounds
 of  high  molecular  weight   (i.e., chlorinated phenols)  which must be
 removed.  For this reason, EPA believes that GAG are  transferable  to
 application in this industry.

 Minor a 2  describes  the  benefits  of  activated  carbon  treatment as
 follows:

      "The properties of many organic chemicals complicate conventional
      biological treatment.  Activated  carbon  can  be  an  attractive

      systemf fo               ^ f°11OWing **™^*S °*er biological
      1.    insensitivity to toxics (and will in
           fact remove most toxic organics) ;
      2.    less sensitivity to temperatures;
      3.    less time required for start-up;
      4.    higher removal of BOD, COD,  and TOC
           for many (but not all)  wastes;  and
      5.    effectiveness in streams with high
           dissolved solids.

      "Since  it can be regenerated and  entrainment  into the   wastewater
     nh                      . by  screens'  th*  granular  carbon  has  been
     chosen  over  powdered  carbon  in the majority of  applications.   The
     technology for  evaluating the applicability of  granular activated
     carbon  and the  ability to design  commercial  systems  from  pilot
     data are well established.                                  t^-tut

     "The ability of activated carbon  to be regenerated for economical
     reuse   is  a distinct  advantage.    Both  powdered  and  granular
     carbons are  capable of being regenerated by existing  technology.
     Granular   activated   carbon   is    regenerated   thermally   at
     temperatures of  1600-1800<>F.   Due   to  the  high  hardness  and
     fofof    !   c°D attrition  °f  coal-base  granular carbon, system
     losses  of   5-8  percent  per  cycle  are  commonly  experienced.
               ac^vat?d c*rbon is also regenerated thermally  at 1600-
              applications."91
However,  a  major  inhibition  to  the  widespread  use  of  granular
activated  carbon has been the high capital cost of installing thermal
to^hff^^i11^63 ^ Sma11 installations.  A  possible %oiu™on
to this problem has been developed by a major chemical company whereby
customers  can lease carbon adsorption systems at a guaran^ed monthly

                  ^ ^^^ *** resP°nsibility  *<*  regeneration  at
centra
                                 192

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As mentioned previously, granular carbon has been chosen over powdered
carbon   in   the  majority  of  full-scale  industrial  applications.
Adsorption equipment consists of  adsorbers  or  columns  holding  the
granular  activated  carbon beds through which wastewater flows.  They
can be designed for pressure or gravity flow to  achieve  the  desired
contact  time  of  the  water  and carbon.  Suspended solids and space
considerations are also a  factor  in  adsorber  configuration.   When
suspended  solids are present, they will be filtered out on the carbon
bed.  This dual purpose of carbon beds can  be  usefully  employed  as
long  as the adsorbers are designed to accommodate backwashing and bed
cleaning procedures, such as air scour and/or surface wash.

Performance criteria for the application of activated  carbon  columns
should  be  developed  from continuous on-line pilot scale  (or larger)
apparatus for any complex wastewater.  Because of  the  waste-specific
nature  of  adsorption,  an  approach  to  evaluating activated carbon
performance from on-site investigations has been developed.92 Although
the published document is directed towards the organic  chemicals  and
plastics  industry,  the  general  approach  can  be  applied  to most
wastewaters including those generated by leather tanners.

The effectiveness of granular carbon adsorption in treating industrial
waste was reviewed by D. G.  Hager.93  Examples  of  TOC,  color,  and
phenol removal were demonstrated for 107 different industrial sources.
Fifteen  plants  have  operated  for two years, meeting the adsorption
design objectives.  In addition to the wastewater survey conducted  by
Hager,  a  selected number of adsorption isotherm tests were conducted
on synthetic samples of water containing toxic chemicals as defined by
EPA.  Other data in the literature94 95  96  97  suggest  that  carbon
adsorption  should  be  an  effective  treatment  method  for organics
similar to the designated toxic chemicals, including a wide  range  of
organophosphorus compounds, and polycyclic aromatic hydrocarbons.

Based  on  the  adsorption  isotherm  test results in the initial 1973
survey93, several plants elected to  follow  up  with  pilot  studies.
Fifteen  plants  installed  adsorption  systems;  the results of these
studies are summarized in Table 34.  In  those  cases  where  the  TOC
effluent  appears  high,  the carbon is being used to remove chemicals
prior to conventional biological treatment.  These are chemicals  that
are  toxic  in  nature and would have a tendency to inhibit or destroy
the biological activity of the system.  The data also reveal  that  in
every  case  some  form  of  pretreatment,  such  as  equalization, pH
adjustment or filtration, was used prior to  carbon  adsorption.   All
rely on off-site reactivation of the carbon where both rotary kilns as
well as multihearth furnaces are employed.

To  achieve  advanced  treatment of secondary effluent from an organic
chemical manufacturing  complex,  granular  activated  carbon  columns
following  trimedia  filtration were selected based on extensive pilot
plant data.98 The in-place biological treatment system  was  operating


                                  193

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effectively in removing BOD, COD and TOC from the complex wastewaters;
however,  the  removal  of  color,  odor  and  toxic  constituents was
necessary.  In addition, suspended solids required further reduction.

At  another  chemical  manufacturing  plant,  the  effluent   from   a
coagulation-sedimentation  step  is fed directly to the carbon columns
for removal of organic impurities.  Most notable is the  reduction  of
phenol  which  consistently over several years averaged better than 99
percent." Spent carbon is directed  to  a  reactivation  furnace  for
regeneration.

Filtration  of the effluent from biological treatment systems prior to
introduction into carbon columns is an accepted practice  to  minimize
clogging  of  the  columns.   Application  of  carbon  columns in this
industry is after filtration (Level 6) and upgraded  activated  sludge
biological  treatment   (Level  5).   Granular activated carbon columns
should yield residual concentrations  for  the  significant  pollutant
paramters  as  follows:   BODj> - 6 mg/1; TSS - 3 mg/1; COD - 165 mg/1;
oil and grease - 2 mg/1; total chromium - 0.25 mg/1; TKN  -  14  mg/1;
ammonia  -  5  mg/1;  and  phenol  -  0.1 mg/1.  All of these effluent
concentrations are estimates based  upon  literature  data,  with  the
exception  of:   (total)  chromium  -  0.25  mg/1, or approximately 25
percent removal attributable to removal of residual TSS,  to  approach
the limits of chromium solubility.

Membrane Technology

     General   Various membrane processes that are finding interest in
pollution control applications as end-of-pipe treatment  and  for  in-
plant  recovery  systems  are  ultrafiltration,  reverse  osmosis, and
electrodialysis.  Although these processes are available for producing
a concentrated solution from a relatively dilute  feed,  each  process
tends  to  occupy  a specific region of application due to economic as
well as technological considerations.

In  contrast  to  the  membrane  processes  of  reverse   osmosis   or
ultrafiltration,  however,  electrodialysis employs the removal of the
solute  (with some small amount of accompanying  water)  from  solution
rather  than the removal of the solvent.  Another major distinction is
that only ionic species are removed.  The fact that only ionized salts
will be removed  allows  for  the  simultaneous  separation  of  these
substances  from  any neutral or un-ionized organic matter that may be
present.  Although these features are similar  to  ion  exchange,  the
advantage  is  that in electrodialysis the process is continuous, with
nothing  to  be  regenerated,  hence   no   chemical   additions   are
required.100 The process finds usefulness in treating brackish waters,
removing  dissolved inorganics in 750-7500 mg/1 concentrations, and in
some by-product recovery schemes.  The necessary equipment is  usually
compact,  and proven plant scale performance exists, both in municipal
and industrial applications.


                                  195

-------
                       ionic components of  a  solution  are  separated
   er        USe  °f  semiPermeabl«  ion-selective  membranes  in the
   ecroiaysis  process.   in  water  a  salt  dissolves  to  produce
 positively  charged  anions.   if an electrical field is placed Icrosl
   !^1Utl?n'  the  cations  migrate  toward  the  negatively  charged
 cathode  while the anions migrate in the opposite direction toward ?he
 £?£*   Y char?ed an0de'   Cation-exchange  membranes  are  permeabll
 simnarlv^asr™? Y  -tO  Cations'  while  ™i™  exchange  membranes
 similarly pass only anions.   Because  of  the  alternate  soacino  nf
 cation   and   anion   permeable  membranes  in  the  electric  field
 compartments of concentrated and dilute solutions (salts)  are  formed

 dUutio^idTanl *£t0 /hlCh  th? •fCed  W3S  i^roduced  become th4
 referred  in  ~  ^   streams  exiting  from  these  compartments  is
 referred  to  as  the dilution stream (any organic matter present will
 remain in this stream).    The  stream  issuing  from  the  concentrate
 compartments is the brine.                                  concentrate

 In  commercial  practice  the  basic appratus for electrodialysis is a
 F?™ r,?f*^CtangUlar membranes terminated on  each end by an electrode.
 Flow of the process streams is contained and  directed by spacers   that
 alternate  with the membranes.  The assembly  of  membranes? spices  and
 electrodes is held in compression  by   a  pair  of  end   places    The
 apparatus  thus  resembles   a plant-and-frame filter presf.   Ancillary
 exce        nC"? POW6r  SUPPly'  pUm*S'  and Piping, is  conventional
                       components  are  used wherever possible to  avoid
                                                -~ — • •*•"*•'  £^^-«hx t^f ,*,*^ju v*  *—V  d V VJ JL L4
 process  streams.  C^entS  ""*  the  Production  of  metal ions into the


 Since  unwanted   side-reactions  of  hydrogen gas  and alkali formation
 take place at  the cathode  while  chlorine and acid  form at  the  anode
 these two compartments must be provided with separate flush streams?

 ±^?h  *'!^!0dialySiS  1S  n0t  a new P"cess ™* has, in fact, been
                                                       -      sss
                                                        .
the low level of technological development.                Because  of
Most  of  the stable membranes today, however, are based on copolymers
of  divinyl-benzene-styrene  with  ion-exchange  groups.   The  cation
available
                                 196

-------
Most  membranes permit operation up to 50 degrees C, although membrane
development activity is attempting to raise that limit.   The  ability
of  the  different  types of membranes to withstand pH extremes varies
considerably.  For example,  some  are  stable  in  acid  environments
ranging  from  5  to  35  percent  HJ2SO4  and  from  4  percent  up to
concentrated HCl.  On the alkaline side, some membranes cannot be used
at all, while others are claimed to be  stable  in  50  percent  NaOH.
Almost  all  of  the  electrodialysis membranes are quite sensitive to
oxidizing solutions.  Some permit short duration  exposure  to  1  ppm
chlorine while needing less than 0.1 ppm for long-term operations.

Fouling  of  the  membranes is the primary disadvantage of the system.
This may occur through scaling  (the chemical precipitation of  salts),
which  is  caused  by  exceeding solubility limits.  Suspended organic
matter also needs to be removed down to 50-100 microns.  The  physical
configuration  of the electrodialysis stack affects its susceptibility
to solids fouling.  Iron and manganese should be limited  to  0.2  ppm
combined.   Trivalent  ions, such as aluminum and phosphate, may cause
increased electrical resistance.  Some organic matter, including ionic
surfactants  (MBAS), and tannic, fulvic, and humic acids,  as  well  as
butyrate  and  larger  esters, can cause membrane blockage.  To reduce
membrane fouling, activated carbon pretreatment, possibly preceded  by
chemical precipitation and some form of multi-media filtration, may be
necessary.

Other  limitations  to  this  process  are  the  high  initial  costs,
requirement for  skilled labor, high energy costs,  need  for  membrane
cleaning and replacement, sophisticated equipment and  instrumentation,
and the production of excess brine waters.

The   principal   action   of  electrodialysis—to  concentrate  ionic
materials—enables  consideration  of  systems  which  accomplish  the
following  separations:   to reduce the volume of brine waste streams;
to recover inorganic salts;  to  remove  inorganic  salts   from  waste
streams to facilitate  further treatment; to separate and recover ionic
materials  from  complex aqueous solutions containing neutral organics;
and to concentrate acids.

In the metals  industries,  electrodialysis  can  be  used   to  recover
metals  from   plating  waste streams.101 Substantial disposal problems
exist  from depleted plating baths and rinse waters.  Materials sud.  as
cyanides of  zinc and cadmium can be reconcentrated  to bath  strength
and can be reduced  in  concentration to very low  levels.  A  closed-loop
recovery  process103   incorporating  electrodialysis   and ion-exchange
permits complete recovery  of nickel, allows reuse of the dilute stream
for rinsing, and recovers  the acid required for  the   regeneration   of
the   ion-exchanges.  Copper and chromium have also  been recovered from
etching processes; while a waste stream of  dilute  ammonium  fluoride
from  glass etching  has been successfully separated  and concentrated  by
electrodialysis  for further treatment.


                                  197

-------
 Within  the  leather  tanning  and  finishing  industry,  it mav crove
 feasible to remove such trace inorganics as  chromium/copper?  lead
 nickel,  and  zinc by the electrodialysis process.  This remains to be
   "                                                   — titutents° £
 Bleaching  wood  pulp  with chlorine or hypochlorite solution yields a
 copious effluent stream of salty water,  the  disposal  of  which  has
 become  a significant problem in the paper industry. io«  By the use of
 electrodialysis, an effluent of 4000 ppm Nacl can be separated into  a

 UP to Jfooo1 n°ntal^n9 5?° PPm °r 16SS °f Salt and a ^rine stream of
 up to 150,000 ppm.  The water  stream,  demineralized  to  the  ouritv
 required  by the process, is recycled as wash water.  The brine stream
 is electrolyzed in a membrane cell to sodium  hydroxide  solution  and
 chlorine;  these  substances may be used directly, or part of each mav
 be combined to form sodium  hypochlorite  solution.    Thus  thf brine
 stream is also returned to the process.                          orine

 By using a process similar to that described above,  it may be possible
 to  significantly  reduce  the  total  dissolved  solids  and chloride
 concentrations present in tannery wastewater.   The largest portionfof
 the dissolved solids are sodium chloride and calcium sulfate?   Sodium
 on ?£  '„   1C^  C3n te f°Und in the ran9e ^ 500-8900 ppm (depending
 on the category) ,  comes principally from removal of  salt or brine from
 the raw hides by washing and also from  salt  added   in  the  cicklina
 operation.   Used  in  conjunction  with  total   dissolved solids  thl
 chloride parameter indicates percentages of other  dissolved  solids
 *r^  °,   ^he  substantial  amount  of  dissolved  s^liS/chloridls
 present,  electrodialysis  may find application  in reducing these  minor

                                                             **
                                                                    any
 Whenever  an   effluent  stream   contains an organic  or  inorganic  ionic
 material, electrodialysis   offers   a  possible  method   for  recoverv
 separation,   segregation,   or concentration of that  material  Provided
                       re
-------
pollutants discharged by tanneries to POTW's or surface waters.  These
technologies  are  pertinent  to  the leather tanning industry because
they (1)  reflect current practices of the industry,  (2) were evaluated
during demonstration studies conducted by the industry,  or  (3)   will
control or remove selected pollutants.  In instances where the control
of specific constituents is a primary concern, technology transfer was
necessary.   An example of this approach is the upgrading of secondary
biological treatment with PAC  addition.   To  control  toxic  organic
compounds   and  heavy  metals,  EPA  assessed  this  technology  from
information developed by the organic chemicals and petroleum  refining
industries and then applied it to leather tanning effluents.

Applicable  technologies  for  the  leather tanning industry and their
performance were determined upon the best available  information.   As
can be seen from Figures 4 through 8, segregation of the waste streams
from  the  beamhouse  and  tanyard  operations  is an integral part of
comprehensive waste management for the  industry.   For  subcategories
with  beamhouse  operations,  the  segregated  waste  stream  will  be
subjected to sulfide oxidation  and  flue  gas  carbonation.   Ammonia
substitution  in  the bating process and chrome recovery and reuse are
applicable to the tanyard processes.   The  effluents  resulting  from
these measures, which are defined as Levels 1 and 2, are then combined
for  equalization  followed by coagulation-sedimentation  (Level  3).  A
schematic  of  the  appropriate  end-of-pipe  treatment  technologies,
including Level 3, is provided in Figure 9.

The effectiveness of the selected technology scheme which includes in-
plant  controls  and  end-of-pipe treatment is summarized in Table 35.
For  each  level  of  technology   through   Level   3    (coagulation-
sedimentation) ,  long-term  performance  is  shown in terms of percent
removal for the  selected  parameters.   Effectiveness  for  Levels  4
through  7  in  removing  pollutants is expressed as residual effluent
concentrations over a long term.

TOXIC POLLUTANT REDUCTIONS

The list of 129 toxic  pollutants  is  divided  into   four  groups  of
chemicals:   volatile  organics,  semi-volatile  organics,  inorganics
 (primarily metals), and pesticides and  PCB«s.   The   first  group  is
primarily  composed  of  chemicals  that  readily  vaporize at ambient
conditions.  Common solvents   such  as  benzene,  toluene  and   carbon
tetrachloride  are  typical chemicals in this group.   Removal  of these
chemicals from wastewater would occur any time the wastewater  is not
confined  in  a completely enclosed container such as  a pipe or  a full
tank.  The removal rate  is  substantially  increased  by  introducing
turbulence  in  the  wastewater   from  any  source such as a mixer, an
aerator or in cascading flow in a treatment device.    The  removal  of
these chemicals as a vapor results in a discharge to the  atmosphere.

The  second   group  of chemicals, the semi-volatile  organics,  includes
higher molecular weight organics  such as phenol  and  the  substituted


                                  199

-------

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phenolics that are used as hide and leather preservatives.  Removal of
some  of these compounds from wastewater is known to occur in a number
of ways, such as oil-water separation  by  skimming  in  sedimentation
tanks,  and  biological  treatment  by  activated  sludge.   For other
chemicals in the group, no determination of an effective technology to
remove them has been made or reported.  Secondary biological treatment
removes phenol.
            *
Physical-chemical mechanisms such as adsorption of  the  chemicals  on
settleable  and  suspended  solids  or  entrainment  or  reaction with
additives or reaction products in precipitation,  coagulation,  and/or
sedimentation has been demonstrated to be effective in toxic pollutant
removal.

The  inorganic toxic pollutants are the metals plus cyanide.  Chromium
is listed as one of these pollutants and is in widespread use  in  the
tanning  industry.   Specific processes to control, recover, or remove
chromium have been described previously in this section.  Treatment by
physical-chemical means is the primary removal  mechanism  for  metals
removal.   Cyanide  removal  has not been specifically applied in this
industry as it has been in the electroplating industry.

Pesticides and PCB's comprise the fourth group  of  toxic  pollutants.
Physical-chemical   methods,  especially  adsorption,  are  reportedly
effective in removing pesticides from wastewaters.  Similar technology
is being installed to remove PCB's from wastewater  by  a  plant  that
previously manufactured PCB's.

The effectiveness of various end-of-pipe treatment systems in removing
toxic pollutants from leather tannery wastewater is indicated in Table
36.   These  results  originate from the field sampling and laboratory
analysis of wastewater from 22 tanneries and two POTW's with  a  large
proportion of tannery wastewater to treat.

In  Table  36,  the  notation  ND  indicates that the compound was not
detected with the analytical procedure prescribed  for  that  specific
sample.   Sometimes  ND  notations  in the "INF"  (influent) column are
followed by indications of presence  of  the  compound  in  the  "EFF"
 (effluent) column.  The determination of toxic pollutants at low-level
concentrations  is  a question of detection of the compounds, with the
analytical methodology not the absolute  determinant  of  presence  or
absence of the compounds.  A compound not detected may be present, but
at  a  very  low  concentration.   To analyze some influent samples it
became necessary to dilute them to a considerable extent  and  thereby
reduce  the  concentration.   In some cases, this dilution reduced the
concentration of a compound to a  level  below  the  detection  limit.
This  prevented  identification  and  quantification  in  the specific
sample and waste stream that it came from.  This produced the influent
ND notations in the table for  some  compounds  followed  by  reported
presence in the effluent stream.


                                 207

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-------
The  trace "tr" designation was used to indicate the identification of
the presence of a compound but with insufficient  quantity  (generally
less than 10 ug/1 for organic compounds)  to quantify its presence.

The results in this table suggest a number of conclusions, as follows:

     1.    Volatile organics are largely removed in any type  treatment
          system  that  is  in  use  in  the leather tanning industry,
          except for some degree of persistence  of  chloroform.    The
          uniformity  of removal is probably due to the volatility and
          resulting ease of stripping these compounds  from  solution.
          It  also  appears  that  this occurs regardless of treatment
          effectiveness on  any  other  pollutant  parameters  whether
          conventional, nonconventional,  or toxic.

     2.    Semivolatile organics also receive some degree of removal by
          all waste treatment systems in use.  Those systems that  are
          most    effective   in   removing   the   conventional   and
          nonconventional pollutants (EOD5f TSS, etc.)   also  seem  to
          be most effective on semivolatiles.

     3.    Metals comprise the inorganic group of toxic pollutants  and
          include  chromium.   All of the treatment systems remove the
          metals to some extent; and performance on the  metals  seems
          to    correlate    with    removal   of   conventional   and
          nonconventional pollutants, most importantly TSS.  The  most
          effective  treatment  system  on  metals  is  the  physical-
          chemical system.

     4.    The fate of the toxic pollutants removed from the wastewater
          was not determined.  However,  EPA  believes  it  is  highly
          probable  that  a  substantial  percentage of the pollutants
          removed are removed  with  the  solids  separated  from  the
          wastewater.

     5.    In  general,  effective  waste  treatment  for   the   toxic
          pollutants seems to correlate well with effective removal of
          the  conventional  and  nonconventional  pollutants.  If the
          treatment system does well on the latter, then  it  will  do
          well in removing the toxic pollutants.

SLUDGE HANDLING AND DISPOSAL

A  major  part  of  tannery  waste treatment involves the handling and
disposal of the semi-solid  sludges  obtained  from  liquid  treatment
processes.   The  most  predominant  methods  of  ultimate disposal of
tannery waste sludges include sludge lagoons,  landfills,  dumps,  and
spreading on the land.
                                 209

-------
 Some  attempts  have  been  made  to dewater sludges prior to ultimate
 disposal,  with  varying  success.   The  three  principal  dewater ing
 techniques  include  centrifugation,  vacuum  filtration, and pressure
 filtration.  Centrifuges have appeared to meet with less success  than
 vacuum filters or pressure filters.

 Reducing  the  moisture  content of sludge by spreading on drying beds
 has  also  been  successful  in  some  areas.   This  is  particularly
 attractive to smaller facilities where land area is available.

 One  of  the principal difficulties with tannery waste is the chromium
 content in sludges and the potential toxic impact of this metal on the
 environment.  In testing a heat-treated alkaline sludge, it  has  been
 indicated  that  some of the trivalent chromium may be oxidized to the
 thron^erV°r^  *^e^ <  the  trivalent  chromium  is  converted
 through  the  high  temperature,  high  pressure,  high  pH,   and  the
 oxidizing environment of the heat treatment process.

 Chromium reuse reduces the levels of chromium in the sludge.   Disposal

 sfn!^rve^n^^^in?^heS! 10W6r residual quantities of chromium in  a
 sanitary landfill will reduce environmental problems.

 Prior  to  dewater ing  in  mechanical   equipment,   sludge  is  normally
 o?Rdth^ed b^USG Of *erric salts,  lime,  polymers,  or  a  combination
 of   these.    The quantity and type of  chemicals  required are  dependent
 upon characteristics  of the sludge being handled.

 Dewatering  with mechanical  equipment such as  centrifuges  generally can
 produce  a cake  containing 15 to  30  percent  dry solids.   Plate   and
 frame  filter   presses   have  been  found to  produce  cakes  of 40 to 50
 percent  dry solids..   The  higher  capital  cost  of  filter  presses may be
 l£a£a  a 5T  ** 10Wer  !f ulin*  and  disposal  costs where  landfills are
 located  great distances  from the  tannery or the  POTW.

 Some  sludge  is  disposed  of  on the land,  taking advantage  of its  lime
 content  for  agricultural purposes.  One  disadvantage of this  type  of
 r™5^   Practice is the  potential toxic  effects of chromium or other
 constituents on plants, groundwater, and surface water supplies.

 Lagoons  for dewatering have some  limited uses.  In humid  areas  where
                       °r 6XCeeds ev*P°ration, such application is not
Use of lagoons, drying beds, landfills, and landspreading all  require
key attention to the environmental impacts.  Particularly important is
the   leaching   of  potential  toxic  or  organic  materials  to  the
groundwater supplies or surface waters.  Proper controls must be taken
to ensure that these conditions will not develop                 ^axen
                                 210

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                             SECTION VIII

             COST, ENERGY, AND NON-WATER QUALITY ASPECTS


Plant sizes and  related  production  rates  have  been  selected  for
purposes  of  economic  impact  analysis.  Five typical "model" plants
were selected in Subcategories One and Two; three  model  plants  were
selected  in  Subcategories  Three  and  Seven;  four  model plants in
Subcategory Five; and two model plants in Subcategories Four and Six.

CAPITAL COST ASSUMPTIONS

EPA calculated the waste treatment system capital costs based  on  the
plant production, wastewater flow, and related pollutant load data for
typical  "model"  plants  in  each  subcategory.   Capital  costs  for
specific treatment system components largely depend on the  wastewater
flow or hydraulic load.

The  actual  component  cost  estimates are based on unit cost curves.
The following assumptions are reflected in the capital costs:

1. Costs are expressed in December 31, 1977, dollars.

2. Expected accuracy for these conceptual-type estimates  is  plus  or
minus 40 percent.

3.  Engineering  costs  are  not included in cost estimates.  However,
most states require that design plans and specifications  be  prepared
by  a  registered  professional engineer in accordance with applicable
codes.

4. Construction work to be performed by outside contractor using union
labor and no  work  to  be  done  by  in-plant  labor  or  maintenance
personnel   (except   stream   segregation  work).   The  construction
contractor's overhead and profit are included in the cost estimates.

5. No land acquisition cost is included.

EPA believes that the capital cost estimates in  this  report  may  be
higher  than  the  actual cost that tanneries will incur in installing
the suggested technology.  For example, a pollution control consultant
to the industry reported that to his knowledge none of  the  tanneries
for  which  he  was consulting had used an outside contractor to build
waste treatment facilities, but that the facilities  at  each  tannery
had   been   built  with  in-house  labor.   This  would  represent  a
substantial cost savings.  There are numerous  other  investment  cost
reductions   available   to   the   resourceful   tannery  in  design,
construction,   and  operation   of   treatment   ictechnology.    These
reductions  cannot  be  accurately  defined  or  predicted, nor is the


                                 211

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 effect of them included in the cost data.   The  intent  of  this  cost
 information  is  to  present  maximum  expected  costs  of  wastewater
 treatment technology suggested for the industry.

 ANNUAL COST ASSUMPTIONS

 The  components of total annual cost are  capital   cost,   depreciation,
 and   operating  and  maintenance costs, the latter including manpower,
 chemical,  and power costs.   The cost of capital is estimated to  be  9
 percent  of  the  investment  cost.   This   cost  is an estimate of the
 weighted   average  of  the  cost  of  equity  and  of debt  financing
 throughout  the  industry.    The depreciation component  of annual cost
 was  estimated on a straight-line basis, with no salvage  value  and  an
 assumed-year life for all  capital investment costs.

 The   rate  for tannery labor manhours was set at $5.00 per hour  plus 50
 percent for burden,  supervision,  etc.,  based on information  from  the
 industry.   The electrical  power cost was estimated to be 2.5 cents per
 kilowatt-hour  (kWh).    The  operating year was assumed  to be 260 days
 per  year  in all cost calculations to account for  the  variable  numbers
 of days per week of  operation reported by the industry.   The operating
 year  used  for  the wastewater treatment plant was 365  days per year.
 Operation  and  maintenance   costs  are  based  on  December  31    1977
 dollars.                                                        '

 CAPITAL AND OPERATION AND  MAINTENANCE COST  CURVES

 Using  the  assumptions  stated  above,  total  installed  costs  were
 developed  by the technical   contractors based  upon:  1)   the   design
 factors  presented  in  Section  VII   of this  document  for each unit
 treatment  process, and 2)  updated cost  information for   equipment  and
 material,  labor,  chemicals,  and energy.  Costs  were developed for each
 of   the  treatment technologies described in  Section  VII.   The  capital
 cost  curves  were  obtained   by  plotting the  total  installed   costs
 against  wastewater   flow   rate.   The  annual  operation and  maintenance
 costs were  computed  by totaling the  manpower,  maintenance,  chemical
 and   electrical   power costs.   This total was compared to average flow
 rate  in the  operation  and maintenance  cost  curves.  Cost  curves   were
 generated   for   eight  wastewater  treatment  levels  (as  introduced  in
 Section  VII),   stream  segregation,   and   sludge   dewatering.     The
 rationale, design  basis, and  items included in  each of the  cost  curves
 are described  in  the following sections.
Stream Segregation - Level 1
Because of different in-plant treatment requirements for the beamhouse
and  tanyard  wastewaters,  the  flows  from  these sources have to be
physically separated until after  Level  2  in-plant  treatment.   The
segregation   of   the  beamhouse  and  tanyard  wastewaters  involves
modifications to processing wheels, piping from the wheels to a  sump
                                 212

-------
and installation of the sump system for each of the two waste streams.
The piping and sump pumps have been sized to simultaneously handle the
flow from two wheels.

The   number  of  processing  wheels  that  require  modification  was
determined by dividing the plant production in hides per day  by  270.
The cost of modifying each wheel was computed to be $5,000.  The first
cost  of  the  sump  pumps and the sump pit was calculated at $28,000,
regardless of the plant production rate.  The installed  cost  of  the
piping,  fittings,  valves,  and pipe hangers was computed for each of
the tannery sizes considered.  The  total  installed  cost  for  steam
segregation,  including  piping,  pumps, and modifications, is plotted
versus average flow rate in Figure 10.

The operation and maintenance costs associated with stream segregation
were computed using the following criteria:

     1.  Maintenance  -  20  percent  of  installed  cost  of  piping,
     processing drum modifications and sump pump.

     2.  Operation  - 60 horsepower-hours per processing drum per day.
     Figure 11 shows the annual operation and  maintenance  costs  for
     stream segregation for the range of flow rates considered.

Stream segregation applies to subcategory numbers 1, 2, 3, 6, and 7.

Sulfide Oxidation - Level J

The  recommended  in-plant  process  changes  include the recovery and
reuse of the  chemicals  contained  in  the  unhairing  liquors.   The
recovery  and  reuse  of  the  unhairing  liquors  removes most of the
sulfide content of the beamhouse waste stream.  The remaining residual
sulfide concentration must be completely removed prior to discharge to
the end-of-pipe treatment plant  to  eliminate  the  possibilities  of
corrosion  and  the  health problems associated with hydrogen icsulfide
gas generation.  The residual sulfide concentration in  the  unhairing
waste can be removed by utilization of the sulfide oxidation process.

The  recommended sulfide oxidation process includes two holding tanks,
a  pump, blower, and chemical feeding equipment.  The  spent  unhairing
wastewater  is pumped into the storage tanks, the magnesium sulfate is
added, and the air for oxidation  is  supplied  by  the  blower.   The
design criteria for each of the components included is as  follows:

     1.  Holding  tanks  (each) = 75 percent of daily flow  of unhairing
     wastewater;

     2. blower =  0.22 cfm/lb  (0.014 m3/min/kg) sulfide oxidized;

     3. pump = capable of draining two unhairing vats in 60 minutes;


                                 213

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    1000
  o
  o
  o
 -cn-


  X
  o
  o
  «l

  2  -

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   10
G.RD. 10
,000

	 1 	 1 	
30
	 1 	 1 	
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1 	 1"
100
	 1 	 1" 	 T
000
1 ' 1 '
300.0OO
M V DAY      30
                          100
                                                 900
                                                                           IOOO
                                    AVERAGE   WASTE WATER   FLOW



                    Figure 10.   Capital Cost Curve for  Stream Segregati




                                          2-14
on

-------
  100
   60
IT
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60,000
n— i
i 	 • — • — H
100,000

500,000
MS/DAY' 50 100 »oo 1000
                                   AVERAGE   WASTEWATER   FLOW


             Figure 11.   Operation and Maintenance Cost Curve for  Stream Segregation
                                         2-15

-------
       U.  sulfide  content  (after  recovery  and  reuse) =  3  pounds  fkal/1000
       pounds  (1000  kg)  of hides  processed;  and          Pounds  (*g)/1000


       5.  wastewater volume =  0.52  gallons/pound  (0.0043 m3/kg) of  hide
       processed.


 A  plot  of the installed cost of  sulfide oxidation incorporation based

 on the above parameters is shown  on Figure 12 as  a  function  of  th*

 number of cattlehides  processed per day of operation.

 Sulfide  oxidation  applies to subcategory numbers 1, 2, 3, and 6.


 Ammonia  Substitution - Level _1


 During   the  unhairing  operation,  lime  and  sharpeners are added to

 loosen or dissolve the hair attached to the hide.  Bating follows  the

 reducfthe oH^f the f^-   the.alkaline ««l"ng of thl hides Ld to
 reauce the pH of the solution prior to the tanning operation.  The  nH


 sulfate10withSthrr"?duaSieiimey^CallX  by  ?h?  "action"^ am^niSm
 ^o  I    -     •  residual lime to produce calcium  sulfate.    Most  of









 The  reduced  ammonia  content  in  the wastewater  effluent resulting from
 £
                                                              -
Tr.at.ant  L.v.1   1  inci»ae, both teslaoal =ulfla, oxldatlon ,     h

if "Ite"^??"" Um°* 'na th« -»"«"Mi™ Of M,n..lo.  for  a.oni,
  .
shows the operation and maintenance cost curve for  sulfide
and ammonia substitution in bating,                 suitide


Ammonia substitution applies to subcategory numbers 1, 2. 3, and 6.
                                 216

-------
o
o
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-c/v

X
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 UJ
 en
 z
   .50
    I5L
     100
                                                    ipoo
                               PRODUCTION, NUMBER  OF HIDES / DAY  (CATTLE  HIDES)


             Figure  12.   Capital Cost  Curve for Sulfide  Oxidation
                                          217

-------
  1000
   5fio
a:
<
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o
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O.P. D. 10,
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9
— 1 	 1 	 T
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— 1 	 1 	
80,
>0
	 r~
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"T — [T"
500
1 1 I , ,
100,000
100
— 1 	 1 	
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0,000
                                  AVERAGE   WASTEWATER   FLOW

            Figure 13.  Operation and Maintenance  Cost Curve for Sulfide  Oxidation

                        and  Ammonia Substitution
                                       218

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Flue Gas Carbonation/Sedimentation - Level 2

Flue  gas  carbonation is the final in-plant wastewater treatment step
for the beamhouse wastewater prior to the  equalization  basin.   Flue
gas  carbonation  consists  of blowing flue gas from a boiler into the
beamhouse wastewater prior to  a  clarifier.   The  lime  and  protein
particles  that are precipitated in the clarifier will be withdrawn by
a sludge pump for resale as a by-product or be dewatered for  handling
as solids waste.

The  capital  cost  for  flue  gas  carbonation  includes the flue gas
handling  equipment,  sludge  pump,  and  circular   clarifier.    The
installed  cost  of  the  flue  gas  handling  equipment  required for
carbonation, blower, piping, and  diffuser  is  shown  graphically  on
Figure  14.   The  volume  of  beamhouse wastewater was conservatively
estimated to be 75 percent of  the  total  wastewater  flow  from  the
tannery  for  cost estimating purposes.  The clarifier sizing is based
on a hydraulic overflow rate of 400 gpd/ft2  (16.3 m3/d/m2) .  Figure 15
shows the flue gas carbonation clarifier capital cost, plotted against
beamhouse flow rate.

The operation and maintenance (OSM) cost for  the  flue  gas  handling
blower  and piping was computed at 20 percent of the capital cost plus
the electrical power cost for the  blower.   The  O&M  costs  for  the
clarifier  and  sludge  pump were calculated using 2 manhours of labor
per day, 5 percent of the  capital  cost,  and  the  electrical  power
required  for  the clarifier drive and the pump motors.  The operation
and maintenance cost curve for flue gas  carbonation/sedimentation  is
shown in Figure 16.

Flue  gas  carbonation/sedimentation applies to subcategory numbers 1,
2, 3, and 6.

Equalization and Coagulation-Sedimentation - Level ^3

Following flue gas carbonation the wastewaters from the beamhouse  and
tanyard  combine  and  enter  the equalization tank.  The equalization
tank smooths out pH swings during tank dumps, equalizes surges in flow
rate, and stores wastewater for use by the succeeding treatment  units
during weekends and plant shutdowns.

Figure   17  is a graph of the capital cost of the equalization capital
cost  against  the  total  average  design  wastewater  volume.    The
installed  cost  of  equalization is based upon a detention time of 36
hours; a steel tank on concrete slab; and a mixer size of 0.1  hp/1,000
gallons  (26.4 hp/1,000
 The operation and maintenance cost for equalization is  equal  to  the
 electrical  energy required  for the connected horsepower of the mixer,
 operating 24 hours per day,  365 days per year.


                                  219

-------
    100
    50
 O
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to
O
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Q
UJ
    10
 <

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M V DAY     50
                     REFERENCE: Q INFORMATION  FROM  TANNERY  CONSULTANT
                                   DATA  FROM TANNERY
                         100
                                               300
                                                                      A
6.RD. 10
000
i i r
— 1 	 1 	
50
	 1 	 1 	
000
1 	 1 	
100
1 1 1
000
1 1 -
5 CX
I
5,000
                                                                       1000
                                 BEAMHOUSE  WASTEWATER   FLOW

                  Figure 14.   Capital Cost  Curve for Flue Gas Handling Equipment
                                        230

-------
 1,000
  500
O
O
O
X

I
O
O
O
UJ
(O
z
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  JOOJ
   50
G.RD. K
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3,000
f 5
— T 	 \ 	 n—i 	 1 	
1 50
o too
,000
»
100
[X)
,000
10
-I— 1 1 1
500,000
00
                                 BEAMHOUSE   WASTEWATER    FLOW

          Figure 15.  Capital  Cost Curve for Flue  Gas Carbonation Clarifier
                                        221

-------
      too
     50
   cr
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  LU
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  1000
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 O
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   100
 o
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 to  -I
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6.RD. 1C
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50
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	 1 	 1 	
,000
»
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100
DO
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300,000
00
             Figure 17.
          AVERAGE   WASTEWATER    FLOW

Capital  Cost Curve for  Equalization
                                         223

-------
              was*ewater-  included in the capital cost is the solids-
                      -sssss •ssss.isr a"   -

 The operation and maintenance cost for  coagulation-sedimentation  was

 forerann,f i  Y addlng the.cost of the  coagulation chemicals to the cost
 ^L,*"     manhour requirements.  The annual manhour requirements for
 operation and maintenance labor are shown in Figure 19.


 Treatment  Level  3,  as   described  in  Section  VII,  includes  both

 ^» ^*^°n     coagulation-sedimentation.   The capital cost would be
 the additive costs obtained from Figures 17  and 18.  The operation
 maintenance   costs for treatment Level 3 can be deterSned^rom Fi
 Equalization and coagulation-sedimentation of combined streams applies
 to all subcategories.

 Secondary Biological Treatment -  Level l
                         "' aS  described i« Section VII, consists of
                  tende^  aeration  ^P«  activated  sludge  process.


                                         a-Ksra

         aeration provided by subsurface static aerators;

         aeration basin is an earthen  lagoon  with  Hypalon  lining-
         detention time is determined by F/M of 0.1.
         final clarifier overflow rate is  150 gpd/ft* (6.2
                    maintenance  cost  for  secondary  treatment  is
                    i* n rf*m -v- XN *^O   r-» —,. -~	^
                                                              of
Upgraded Secondary Treatment with PAC Addition - Level 5


As described in  Section VII on  treatment  technology, the  pollutant
removal  effir-i^n™  ^f  ^^4.^,.,^^^  _, ,    /JL     **'      t^oj.j.urant
                                        (treatment Level 4) can be
                                        activated  carbon  to  the
                              224

-------
 1000
  500
O
O
O
-co-
 X
   100
    50
     10
 G.RO. 10,000
 M 3/ DAY     50
                                        50,000
                                                        IOO,OOO
                                                                                            500,000
100
                        300
                                                   1000
                                       AVERAGE   WASTE WATER   FLOW
               Figure 18.   Capital  Cost Curve for  Coagulation-Sedimentation

-------
10.000
5,000
                                                           MAINTENANCE LABOR
100
FT.* 1
V.2
2
BOO
3 5
1,0.
0
>0
l(
	 1 	 r
>U 21
8,000
X> *<
— 1
•»ft
      Figure 19.
             PRIMARY   CLARIFIER  SURFACE  AREA
Annual Manhour  Requirements for Coagulation-Sedimentation

                   226

-------
   100
  90
CT

UJ

\

O
O
o.

•-

X
UJ
o
   10
 IT
 UJ
 O.
 O
 O.P. D. 10,000   I

 M3/DAY     80
                                      80,000
                                                     100,000
                                                                                        500,000
100
                       9OO
                                                 1000
                                     AVERAGE   WASTEWATER   FLOW

            Figure 20.   Operation and Maintenance Cost  Curve for  Equalization

                         and Coagulation-Sedimentation


                                           227

-------
    IOOO
    500
  O
  O
  O
    100
  O
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  to
  z

  ,  sp_
G.RD. 10,000

M 3/ DAY      30
                          100
                                                 9OO
                                                                   900,000
                                                                           IOOO
        Figure  21.
               AVERAGE   WASTE WATER   FLOW

Capital  Cost Curve  for Activated Sludge Secondary Treatment


                     228

-------
   100
   50
o
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-co-

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 <6



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 tr
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 o.
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e.p. o. 10,000
	 1 	 1 1

	 1 	 1 	
	 1 	 1 	
80,000
I — P—
	 1 	 1
100,000
M3/DAY 50 100 300



500,000
1000
                                   AVERAGE   WASTE WATER   FLOW

            Figure 22.   Operation and Maintenance Cost Curve for Activated


                         Sludge Secondary  Treatment


                                         229

-------
 aeration basin.  The carbon will be added manually by the bag into the
 aeration  basin  influent.  Thus, the capital cost is only the cost of
 enough carbon to attain the  desired  concentration  in  the  aeration
 basin, based on the following design criteria:                aeration

      powdered activated carbon concentration = 1800 ppm;

      cost of new carbon (no regeneration) = $0.30/lb ($0.66/kg) ;

      sludge age = 30 days; and

      number of complete carbon replacements = 12 per year.

 The  operation  and maintenance costs were equal to the annual cost of
 replacing the activated carbon lost in the  wasted  activated  sludge
 coltf f or r Jhon3 ^ relationship of annual operation  and  maintenance
 costs for carbon replacement versus wastewater volume.

 PAC addition to activated  sludge applies to all subcategories.

 Multi-media Filtration - Level 6

 Multimedia   filtration  follows  upgraded  activated  sludge   in   the
 treatment  scheme  and  is  defined as treatment Level  6.   The capital
 cost of multi-media  filtration  includes  the  media,   tanks?  pumps
 Piping   valves,  and   installation  and  is  shown graphically  versus
 wastewater  volume in Figure  24.   The  cost data shown on  Figure 24   wal
 fUtratfoTio?   renderin9  industry  study  incorporating   multi-media


 The  cost  curve  for   operation and    maintenance   of    multi-media
 filtration.  Figure  25,  is  based  on  the  following  components:

      Labor   =  1/3 man-year for a system  operating at less than 100,000
      gpd  (379 m3/d) wastewater  flow;

      Labor  =  1/2 man-year  for systems handling more than  100,000   and
      (379 m3/day) ;                                                  yP

      Power  =   10 hp continuous  for systems  handling less than 100.000
      gpd  (379
     Power = 15 hp continuous for systems rated at 100,000 to  250 000
     gpd  (379-948 m3/day) ; and

     Power  =  20 hp continuous for systems handling more than 250,000
     gpd  (948 m^/day) .

Multi-media filtration applies to all subcategories.
                                 230

-------
  100
  50
tr
UJ
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o
o
UJ
o
z

Z JO.
UJ
,000
— 1 	 1 1

— 1 	 1 	
	 1 	 1 	
60,000
I — T~
	 1 	 1 	 r
100,000

500,000
MS/DAY 50 100 300 1000
                                   AVERAGE   WASTEWATER   FLOW

             Figure 23.  Operation and  Maintenance Cost  Curve  for Upgraded

                         Secondary Treatment


                                        231

-------
  1000
   500
O
O
O
   100
a
UJ
  50
  10
G.RD. 10
M 3/ DAY
,000
5
' ' '
0 l(
)0
1 	 1 	
50
	 1 	 1 	
000
»
1 	 1 	
100
X)
	 1 	 1— 	 T
ooo
10
1 I 	 1
500,000
OO
             Figure 24.
       AVERAGE    WASTEWATER   FLOW

Capital Cost  Curve for Multi-Media  Filtration
                                       232

-------
   100
   fifi-
cr

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q.

--

x
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h-
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   10
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O.P. D. 10,000
— 1 	 1 	 T

	 1 	 1
1 I
50,000
r i
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100,000
MVDAY 50 100 300




500,000
IOOO
                                    AVERAGE   WASTEWATER   FLOW

                  Figure 25.   Operation and  Maintenance Cost Curve for

                               Multi-Media Filtration


                                         233

-------
 Granular Activated Carbon Columns - Level 7

 The use of granular activated  carbon  columns  following  multi-media
 filtration will further reduce the pollutant levels of BOD5,  TSS, COD
 and  oil  and  grease.    Granular activated carbon column treatment is
 referred to as treatment Level 7.  The capital cost for  the   complete
 activated carbon column system with two columns is shown on Figure 26
 The costs used in this  document for carbon columns were taken from the
 EPA  technology  transfer document for carbon adsorption. 10*  The costs
 shown in Figure 26 are  based on  an  empty  bed  contact  time  of  30
 minutes.

 The  operation and maintenance costs associated with treatment Level 7
 are summarized in Figure 27 based upon the following design criteria:

      Carbon used = 1300 Ib/mgd treated (0.16 kg/m3) ;

      Carbon  cost  =  $0.34/lb  ($0.75/kg)   regenerated   by    outside
      contract;  and

      Manpower = 2 man- days/week

 GAC columns apply to all  subcategories.

 Physical/Chemical Treatment -  Level
The  Chappel  process,  treatment  Level   4A,   is a patented physical-
chemical treatment  process  which  can  produce  a  treated  effluent
quality  equal  to  secondary  treatment   including powdered activated
carbon followed by  multi-media  filtration.    The  tannery  treatment
train  for  direct  dischargers  using the Chappel process consists of
stream   separation,   in-plant   process   changes   and   treatment
equalization,  primary  coagulation- sediment at ion and then the Chappel
treatment units.  The physical-chemical Chappel  process  consists  of
the following equipment:

     circular  steel  equalization  tank,  8  ft. deep, providing 1 hr
     detention time;

     acid and alkaline chemical addition tanks;

     three steel settling tanks,  8  ft.  deep,  each  providing  6-hr
     detention  time  including sludge pumps, aerators, and agitators-
     and                                                             *

     a clarifier with a 400 gpd/ft2 (16.4 ir^/d/m*)  hydraulic  overflow
     rate.

The  capital  cost of the Chappel treatment process,  shown graphically
in Figure 28,  was  taken  from  a  rendering  industry  study. 106  The


                                 234

-------
 1000
  500
-
X
  100
<
en
   50
6.RO. 1C
M 3/ DAI
),000
f 5
	 1 	 1 	 T
0 l<
— 1 1
50
30
	 1 	 1 	
000
3
DO
100
OOO
10
	 , 	 I T
5OO.OOO
00
           Figure 26.
            AVERAGE   WASTEWATER    FLOW
Capital Cost  Curve for Activated Carbon  Column System
                                         2,35

-------
   100
QC

<

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UJ
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      Ou  I
  *'», iO.GOu


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1 1 1
1 1 | I T
00,000
r — r~
•oo,
	 1 	 1 	 r
000
1 ' 1 '
500,000
                        100
                                               300
                                                                        1000
                                   AVERAGE   WASTEWATER  FLOW


                  Figure 27.  Operation and Maintenance Cost Curve  for


                              Activated Carbon Column System
                                        236

-------
1000
G.PD. 10
M 3/ DAY
,000
5
1 1 1
0 K
I 1
50
>0
	 r — i —
000
»
r T
100
X)
i i I
ooo
10
5
00
                                                                                 T
                                AVERAGE   WASTE WATER   FLOW
               Figure  28.   Capital Cost Curve for  Chappel Process
                                       237

-------
 equalization  settling,  and clarifier tanks were priced using air lift
 pumps at a cost of $750  per  foot  ($2,460  per  meter)   in  diameter.
 Figure  29  is  a  plot   of  the operation and maintenance cost of the
 Chappel process against  treated flow rate.

 Sludge Dewatering

 The sludge  produced   from  the  various   wastewater   treatment  plant
 processes,    such  as  coagulation-sedimentation,  extended   aeration
 activated sludge, and multi-media filtration backwash,  is relatively
 dilute  varying  from 0.5  to  8 percent solids.   To allow for easier
 handling  and  disposal   of  sludge   from  the  wastewater   treatment
 facility,   a  sludge   drying  or  dewatering  device   is  required.   A
 horizontal tank  leaf filter  press   sized  to  provide  700  ft*  of
 filtration  area  per million gallons (17 mi2/i,QOO  m^)  of wastewater
 was used as the basis for the sludge  dewatering cost  estimate.

 The capital costs required for  sludge dewatering  are  indicated  in
 Figure 30.   The operation and maintenance cost estimate for dewatering
 of  the sludge is shown in Figure 31.

 CAPITAL AND OPERATING COST SUMMARY

 Capital  costs  and operation and maintenance costs  have been  presented
 for the  in-plant control,   preliminary   treatment,   and  end-of-pipe
 technologies   applicable   to  leather  tanneries  for pollution control.
 The levels  of technology  indicated correspond with  those presented  in
 Section VII   of  this  document.  The capital  expenditure  required  to
 implement a  pollution control   program to  achieve  these  levels  of
 performance   will depend   on  the  type and extent of  pollution  control
 equipment  in  place at each  tannery,   and  on tannery-specific  cost-
 effectiveness     trade-offs     between    in-plant    and   end-of-pipe
 technologies.    In-plant   technologies usually  involve the  reuse,
 recovery,   or   removal  of  process materials that  are pollutants from
 specific waste  streams, whereas  end-of-pipe technologies  are  applied
 to  the  total wastewater stream  to  reduce  the  pollutant  loading.

 The  costs   for   sulfide   and   chrome  recovery are  not  included in the
 technology tabulation.  Chrome  and sulfide  recovery or reuse  processes
 are being installed or considered  in  the   industry  because   of  the
 strong  economic   incentive  and favorable  return on such investments.
 The trend in the  cost and  supply  situation  for   chrome  essentially
mandates  chrome  reuse, thus eliminating  chrome recovery as strictly a
 pollution control measure.

An  increase in  energy  consumption  will  occur  wherever  additional
wastewater  treatment  or  processing  is  implemented.   Substitution of
raw materials with non-polluting alternatives is possible and requires
no  additional  energy  expenditure.    Recovery  and  reuse   of   raw
materials,  instead  of  once-through  use, will produce an overall net


                                 238

-------
   100
   50
OC
UJ
V
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--

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 (0

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e.p. o. ic
"
>.ooo
i — ' 	 ' — n

i , | 1 1
50,000
1 — T~
	 1 	 1 r
100,000
' 1 '
500,000
M3/DAY 50 100 300 IOOO
         Figure 29.
              AVERAGE   WASTEWATER   FLOW

Operation  and Maintenance  Cost Curve for  Chappel Process
                                          239

-------
  1,000
   500
 O
 O
 O
 X

 I
   100
 O
 UJ
   50
    10
M V DAY
          50
REFERENCE: O COSTS  CALCULATED FROM  LITERATURE
          A COSTS  OF TANNERY  INSTALLATIONS
                                                                           O
                                                                              A
G.RO. 10
,000
1 1 1
1 1 I I 1
50,000
1 1
100
000
1 '
500,000
                         100
                                               900
                                                                         IOOO
                  Figure 30.
                AVERAGE   WASTE WATER    FLOW

           Capital Cost  Curve for Sludge  Dewatering
                                          240

-------
   100
o
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-------
energy savings in the total economy of the industry,  although  energy
consumption in a specific tannery may increase.

MONITORING COSTS

The  estimated  cost  is $300 per sample for analysis of acid fraction
organic pollutants  and  $25  per  sample  for  each  inorganic  toxic
pollutant  based  on  current  sampling  and analytical procedures and
technology.   The  estimated  cost  of  analysis  for  all  pollutants
regulated  by  BAT   (BOD5,  COD,  TSS, Oil and Grease, Total Chromium,
Phenol  (UAAP), TKN, Ammonia and Sulfide)  is  approximately  $100  per
sample.  See Section XIV - MONITORING for further details.

ENERGY REQUIREMENTS

The   design  of  end-of-pipe  wastewater  treatment  plant  units  is
dependent on the performance of in-plant and pretreatment technologies
for specific waste streams originating within  a  tannery.   Reuse  of
process  streams,  recovery  and  reuse of chemicals, and reduction of
wastewater volume are primary aspects of these technologies.  Each  of
these reuse and reduction processes is inherently energy conserving in
the production of leather and in wastewater treatment.

The  removal  or  reduction  of  pollutants  in  any wastewater stream
requires an energy expenditure.  The higher  levels  of  treatment  as
described  in Section VII produce a higher quality effluent with lower
levels of pollutants.  This means a greater energy consumption than at
lesser levels of performance.

NON-WATER QUALITY ASPECTS

Solid Wastes

Characteristics.   Solid  waste  from  a  tannery  with  a  wastewater
pretreatment/treatment system may include any or all of the following:

     1.   fleshings,
     2.   hair,
     3.   hide trimmings,
     4.   tanned hide trim and shavings,
     5.   leather trimmings,
     6.   buffing dust,
     7.   leather finishing residues,
     8.   wastewater treatment sludges, and
     9.   general plant waste.

The  specific  types of solid waste generated by a tannery depend upon
the type of processing operations conducted.    The  quantity  of  each
type  of  waste generated depends upon the volume of production at the
tannery.


                                 242

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Tanneries which generate fleshings and hide trimmings  sometimes  sell
these  waste  materials  to  rendering plants, or occasionally to glue
manufacturers.  Since these waste materials  are  highly  putrescible,
daily collection is required.  Very small tanneries which process only
a  few  hundred  hides per day often find it uneconomical to sell this
waste since the by-product recovery value is exceeded by the  handling
and transportation costs.

Most  vegetable  leather  tanneries and a few chrome leather tanneries
remove hair from hides using a hair save operation.  At a few of these
tanneries, the hair is washed, dried and baled, and subsequently  sold
as a by-product.  Most of these plants, however, merely screen out the
removed  hair  and dispose of it in landfills.  A few plants allow the
hair to enter the  general  plant  wastewater,  which  can  result  in
plugging  of  pipes,  clogging  and  destruction  of pumps, fouling of
clarifier sludge raking mechanisms and weirs, etc.  Use  of  the  hair
save  method  is declining in favor of the hair-pulp method.  As noted
in Section III, however, some tanners still use a modified  hair  save
beamhouse  which  produces hair that is disposed of in a landfill.  At
tanneries using the hair pulp method of  hair  removal,  the  hair  is
dissolved and becomes part of the wastewater stream.

Some  chrome  leather  tanneries,  particularly  split leather tanners
located in the northeastern U.S., generate large quantities of  tanned
hide trimmings and shavings.  This waste material can be sold as a by-
product.   By-products  are  used  in  the  manufacture of fertilizer,
chrome glue, hog feed supplement, and leather board,  and  provide  an
energy  source  for  steam  production.   The majority of this type of
waste, however, is disposed as solid waste.

A recent industry study estimated that the  total  quantity  of  solid
waste  disposed  in  the  land in 1974 was 203,000 metric tons.106 The
distribution of the total quantity of waste  between  the  four  major
waste types was as follows:
                                 243

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                               Table  37

         Industry Estimates  for Land  Disposal of Solid Wastes

                                             Percent of
     Type of Waste            Quantity*      Total Waste

     Wastewater                122,000            60
      treatment residues
       (screenings 8 sludge)
     Tanned hide trimmings      71,000            35
      & shavings and leather
      trimmings
     General plant waste         6,000             3
     Leather finishing           4,000             2
      residues

     *metric tons generated in 1974

Reuse  and  recovery  with reuse are two technologies that will reduce
solid waste generation in wastewater  treatment  plants.   Alternative
chemicals use may have similar results.

Pollution  control  applied  to  specific waste streams before all are
combined into a single total wastewater stream  may  produce  a  solid
waste,  but  the specific contaminants in the solids will generally be
known and in the most concentrated form.  Such solid wastes  are  most
manageable  in  terms  of proper control and disposal.  Numerous small
quantities of solid waste of more concentrated composition may be less
economical  to  handle  and  transport,  but   will   be   much   more
environmentally   manageable   than   a  single,  large,  dilute,  and
multicontaminated solid waste.  The latter would usually result from a
waste treatment system confined exclusively to end-of-pipe technology.

The primary contaminants of solid wastes from tanneries  are  chromium
and  other  heavy  metals occurring in the wastewater, such as copper,
lead, and zinc.  Repeated reuse of  the  chromium  containing  streams
and/or  recovery  and  reuse  will  reduce chrome contamination of the
solid wastes.   The other metals originate in the raw materials  or  as
corrosion  products  from  the equipment in the tanneries.  The former
can be controlled by changing raw materials or their  composition,  or
by   eliminating   the   use   of  such  raw  materials.   Alternative
construction materials for equipment would be the best solution to the
corrosion source.

Disposal Alternatives.   Approximately 60  percent  of  the  wastewater
treatment  residues  produced  come from chrome leather tanneries with
primary and/or secondary wastewater  treatment  facilities,  while  20
percent  originate  from  chrome  tanneries  with secondary wastewater
treatment systems.   Treatment plant sludge from  chrome  tanneries  is


                                 244

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normally  dewatered  prior  to  disposal.   Sludge  dewatering  may^be
accomplished using gravity or mechanical  means.   Gravity  dewatering
(sequential  settling)   is relatively uncommon; however, sludge drying
beds on the tannery plant site are used by some  tanners.   Mechanical
sludge  dewatering  is  normally  accomplished  using  vacuum filters,
centrifuges, or filter presses.   These  three  mechanical  dewatering
techniques  have  all  been  found to be effective in producing sludge
cakes ranging from 10 to 40 percent  solids.   There  seems  to  be  a
preference  for  filter  presses  due to the drier (40 percent solids)
filter cake produced.

Secondary wastewater treatment sludges from  vegetable  tanneries  are
normally  dewatered  in evaporative lagoons, after which the sludge is
either used as a  soil  conditioner  or  disposed  of  in  a  dump  or
landfill.

Sewer  sump  sludge  is composed primarily of precipitated lime and is
not normally dewatered prior to disposal*  Dumps and landfills are the
most common disposal facilities for this waste.

The different types of solid waste disposal  facilities  utilized  and
estimates  of  the  proportion  of the total quantity of tannery solid
waste going to each type of facility are shown in Table 38.  As shown,
nearly all tannery solid waste is  disposed  in  landfills  or  dumps.
Trenches,  lagoons,  and certified hazardous waste disposal facilities
are currently used almost exclusively for sludge  disposal.   A  small
percentage  of  tanneries  operate their own disposal sites.  Tannery-
owned  disposal  facilities  are  usually  associated  with  vegetable
leather tanneries and are the result of the plant's remote location or
the  fact  that  other disposal sites will not accept the solid waste.
Most tannery solid waste which is land disposed  contains  substantial
concentrations  of  trivalent chromium  (up to  several percent on a wet
weight basis) and, in many cases, copper, lead, and zinc as well.  For
example, the  "typical"  concentrations  of  certain  constituents  in
tannery  sludge  are  presented  in  Table  39.  As shown, sludge from
vegetable leather tanneries is the only type which does  not  normally
contain  significant  heavy  metal  concentrations,  unless concurrent
chrome tanning or retanning occurs at  the  same  plant.   The  recent
trend  toward  chrome reuse or recovery would  not be reflected in this
data and would suggest lower chrome concentrations in future sludges.

EPA believes that many  of  the  toxic  pollutants,  especially  heavy
metals,  are  removed with the sludge.  There  are no data available on
the fate of these pollutants  or  the  actual   distribution  of  these
pollutants   between   the  solid  and  liquid phases.   These  toxic
pollutants would thereby become part of the solids to be  disposed  of
from leather tanneries.  No analyses were made for toxic pollutants at
the  time  the  data  in  Table  39  was generated, thus no additional
information is  currently  available  regarding  toxic   pollutants  in
sludges  from leather tanning waste treatment.   A substantial amount of


                                 245

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                   Table  38
Disposal Sites Utilized
General Category of
Disposal Site
Landfill







Dump



Trenches or lagoons



Certified***
Specific Type of Disposal Site

municipal sanitary
private sanitary
municipal engineered*
private engineered
municipal converted**
private converted
on-site tannery

municipal
private
on-site tannery

municipal
private
on-site tannery
private
Percent of
Waste Disposed
60
3
3
5
10
20
1A
5
25
20
1
A
9
A
A
1
6
  *Engineered disposal sites which do not provide daily cover
 **Dumps which have been coverted to landfills without being engineered
***Certified hazardous waste disposal facilities
                                     246

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                 Table  39
"Typical" Sludge Characteristics*
Constituent
Solids content
Chromium (mg/1)
Copper (mg/1)
Lead (mg/1)
Sulfides (mg/1)
Phenols (mg/1)
Chrome leather tannery
pre treatment /treatment sludge
before
dewatering
5-10
3,000-6,000
100-150
10-25
20-50
<10
after
dewatering
20-30
10,000-15,000
150-200
50-150
50-150
<10
Chrome leather
tannery sewer
sump sludge
(not dewatered)
5-15
2,000-4,000
100-200
10-25
30-60
<10
Vegetable leather
tannery secondary
treatment sludge
(not dewatered)
3-6
<5
<10
<5
25-50

-------
 data   will   become   available  and  will  be  considered  prior  to
 promulgation of these regulations.

 The fact that 60 percent of tannery solid wastes are  waste  treatment
 residues  and  that  the disposal sites reportedly used include a wide
 variety°f types Su9itted   facility.    See    43 FR 185ol
 (April 28, 1978).  Finally, the proposed treater, storer,  and disposer
standards  would  establish technical design and performance standards
 for leather tanning  waste  storage  facilities,  and  for  landmis
basins, surface impoundments, incinerators, and other facilities wher4
such  wastes  would  be  treated  or  disposed,  as  well as security
contingency  plan,  employee   training,   recordkeeping,   reporting
                                 248

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inspection,  monitoring  and  financial liability requirements for all
such facilities.  See 43 FR 58946, 58982 (Dec. 18, 1978).

Hide and Leather Waste Alternative Uses

The following discussion was taken from  a  report  prepared  for  the
Tanners Council of America  (TCA), February 18, 1977.

The  four  use  areas selected for analysis were chosen to consider as
broadly as possible all categories of solid  waste  and  also  several
types  of  initial  processing   (i.e.,  size  reduction, incineration,
pyrolysis and hydrolysis).  The use areas selected for analysis were:

     1.   Incineration of blue split and finished leather waste;

     2.   Fiberized leather for loose building insulation;

     3.   Pyrolyzed leather waste to make  activated  carbon  and  by-
          product chemicals; and

     4.   Hydrolyzed leather and cattle hair to make leather and  hair
          meals for use in animal and pet foods.

Incineration.   Incineration  of various leather wastes with provision
for  useful  recovery  of  the  released  energy  is  a   surprisingly
productive  use  for  the materials.  Leather is a "clean" fuel in the
sense that it contains virtually no sulfur.  The  heating  value   (dry
basis)   is  about  80  to  90 percent as much as that for a low-sulfur
Western coal.

The heating value of wet blue waste is naturally  diminished  somewhat
by  the  water present, but it still amounts to about 55 to 75 percent
of that for a low-sulfur  Western  coal.   By  burning  the  available
leather  waste,  a  blue split tannery could save nearly all the money
now spent for coal or fuel oil to furnish  the  required  process  hot
water.    The  incinerators  could  probably  be  switched over to coal
without any problems when and if better uses  for  the  waste  leather
were developed, making this kind of venture essentially risk-free.

In  addition  to the recovery of energy, incineration of chrome tanned
leather waste also permits the recovery of a  non-renewable  resource,
chromium  oxide.   In one case, an ash from the incineration of chrome
tanned  waste  contained  2.23  percent  hexavalent   chromium.    The
trivalent  chromium   (Cr^OJ)  content  of chrome tanned leather ash is
known to range from 13.5 to 58.3 percent.

The incineration ash would have a minimum  value  of  about  $200  per
contained  ton  of Cr2O3 on the basis of the current value of imported
chromite ore.  If the ash could be upgraded to a pigment grade product
                                 249

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 (99-1- percent Cr2O3) , it could be sold for about $1 per  pound  as  the
 purified pigment.

 on  the  basis of competition with a low-sulfur Western coal at $19 to
 $21 per ton delivered in Chicago, blue leather  waste  would  have  an
 approximate value of $11.75 to $15.75 per ton (dry basis).   This value
 takes account of the heat required to evaporate the water from the wet
 waste.    sale  of the ash would add about $4 per ton to the realizable
 valae of the blue leather waste  by  incineration,  making  the  total
 realizable  value by  incineration in the range of $16 to $20 per ton
 (dry basis).

 The capital cost (installed)  of an incinerator handling about 1.2 tons
 of waste per hour would be at least $600,000.    such  an  installation
 would furnish 8,645  Ib/hour (19,040 kg/hr)  of steam.

 "Poured"  Insulation.    Ground  or  fiberized  leather  waste has many
 attributes which make it a good candidate material for use  as a  loose
 insulation  for  residences  and  light  commercial structures.   It is
 strongly  resistant   to  environmental  degradation  and surprisingly
 f^a   S  to  ignition,   even  though it can  be incinerated.   A study
 sponsored by the Tanners'  Council of America found only one company in
 the business of producing a fiberized leather  product.   There  was  no
 indication  of   any   effort  to  promote  the  material for insu^tion
 pur pose s.

 No measurements have  been made  on  the  insulation   performance  of
 fiberized leather, but  measurements  of its  apparent bulk density place
 the  material   in the  range  of granulated  cork  and chopped cellulesic
 insulation.   The thermal  conductivity of bulk  leather  is  comparable to
 o^i*°r P?perV a^in indicating that  a  fiberized leather   material
 should perform  technically much like cellulosic  insulation.

 The  chief  problems to be dealt  with  in developing  fiberized leather as
 *£  .1^Ulati?n  material are the cost  of  fiberizing  and  the  requirement
 that the product be odorless.   Both  of these problems   can   likely  be
 SOlKeK;  KTh\  t0tai  COSts   for  a   f^erized   leather   product would
 probably be about  $110  per  ton,  which  would  be  comparable   with
 cellulosic insulation at $240 per ton.                    y*±au±e   wirn

 The  market  for  all  insulation material has grown remarkably in  the
 last few years  due to the  rapid increase in the cost of all  forms  of
energy.   The growth in the use of cellulosic insulation materials has
been at the rate of 34 percent compounded annually ove^the  last   few
years.   It  is  believed that in 1976 the total market for cellulosic
 sHoo  ?onrnfab£Ut  30?'°°£ t0nS-  This  may  be  Compared  with  the
in'the un?ted°ltates?e ^^ "*** M±M tO be avai^ annually
                                 250

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Activated Carbon.  Upon heating leather waste to a temperature of  400
degrees  C,  a  50  percent  yield  of  a  hard granular char could be
obtained.  This has been interpreted to mean  that  leather  could  be
converted  in  about this yield to a hard, granular, activated carbon.
Although there are three literature  references  during  the  last  20
years  to  making  activated carbon from leather wastes, none of these
references noted that hard granules could  be  obtained.   This  is  a
significant  feature  because  hard  granular  activated  carbon  is a
premium material.

Activated carbon is manufactured commercially in the United States  by
nine different companies.  A new producer completed a semi-works plant
in  1976 and plans to complete a full scale plant in 1978.  Production
will be based on a new proprietary one-step process in  contrast  with
the  two-step  processes  used  by  the  other producers.  It has been
suggested that future work on  the  conversion  of  leather  waste  to
activated  carbon  should be directed toward the development of a one-
step process in view of the energy conservation possibilities in  such
an approach.

The  selling prices for granular activated carbons are in the range of
$0.40  to  $0.50  per  pound   ($0.88  to  $1.10  per  kg).   This   is
significantly higher than the $0.10 to $0.12 per pound  ($0.22 to $0.26
per  kg)  prices  paid for powdered activated carbons.  The price of a
granular  carbon  reflects  both  the  absorption  efficiency  of  the
material and its resistance to attrition in use  (i.e., its hardness).


Activated  carbons  are  also  used  to  remove: tastes and odors from
potable  waters;  impurities  and  colored  substances   from   sugar;
impurities  from  a great variety of chemicals; and harmful or odorous
substances from gaseous effluents.  A small but well-known use is as a
component in cigarette filters.

The energy costs for charring leather wastes  and  then  treating  the
char  to  activate  it  are  no  doubt  significant factors of unknown
magnitude.  Capital costs are evidently also an important factor.  The
volatile materials evolved in the carbonation process would  at  least
have  value as fuel.  It seems likely that the ammonia given off could
be advantageously recovered for use as  fertilizer.   The  mixture  of
volatile  organic  materials also evolved might have value as chemical
intermediates greater than their value as fuel.

Leather  and Hair Meal for Feeds.  Although both leather and  hair  are
protein  materials, neither of them is digestible as such.  Hydrolysis
will render each of them digestible, and both of the  resulting  meals
have  been  shown  to  be  useful  supplements  in diets for swine and
poultry.
                                  251

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 Hair meal is very similar in amino acid composition to  feather  meal
 which  is  a well-established ingredient in poultry diets.  Therefore
 feathe!remeal0 nutritional utility* hair meal is the full equivalent  of

 In the  case of ruminants  (sheep and cattle) , hair meal could  be  used
 bPranS^L V?;rtually  ^ of the nitrogen requirements of the animals
 sheep  and Yc^?.n° well-defin?d ^^o  acid  requirements.   Because
 sheep  and  cattle can  use  nitrogen  from a number of very low cost
 sources (urea, grass, alfalfa, etc.) it is  believed that  hair  meal
 would be too expensive for inclusion in their diets?

 However,  there  is  some danger that hair meals  might be contaminated

 "^^

                     attempt  is  made  to  Lrket  haL     *
 Animal consumption of feather meal is currently  100,000 tons  annually
 ^*>,ample s"pPlie.s available.   Hair meals would compete directly with
 feather  meal,  which  sells  for  about  $185   per  ton.  The cost of
 recovering, washing, and drying  hair amounted to $120  per  ton    ?n
 making  hair meal,  the  drying would  not take  place  until "after
 hydrolysis, so  that hair preparation would be somewhat less £han  $120
 ^"i T~OXl •

 The  basic  costs associated with the conversion of hair to a dry meal
 amount to about $65 per ton.   The total costs ($180 per ton) are  well
 below  the  present ceiling of $300 to $340 per ton set by  the current
 selling price of feather meal.   However, present  protein  prices  are
 high  because   the 1976 soybean  crop in the United States was about 20
 percent below the 1975 crop and  the 1976 foreign crop III  also  below
 expectations.   At the same time, demand has remained strong!

 Leather  meal   is  permitted  as  a component in the diets of swine at a

 i^te^ar^a^^V"118 is t0° Sma11 an  amount  to  ««*e
 p^T    *  i-      U  attractive  as  a  component in swine rations
 However,  feeding tests with broilers indicated that 6  percent  leather
 meal  in the diet afforded an economic advantage over  ttrSntrolttrt
                                    ***«**<**  ^-ther  meal "and
Leather  meal has not yet been approved  for inclusion  in poultry diets
s«fiS^.«%.5SG? a^if^-£s*jiissuajs
SETS     srta'            -           --     "
                               252

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Dioxins are known to have been impurities in the  chlorinated  phenols
used  as  fungicides  in the processing of hides into leather.  Recent
advances in the manufacture of chlorinated phenols have led  to  great
reductions  in  the  amounts  of dioxins contained in these fungicidal
phenols.  High temperature drying of hydrolyzed leather may also  lead
to  the  conversion of the small amounts of chlorinated phenols in the
hides into dioxins.  If this were the source of the dioxins, then  the
formation of dioxins might be avoided by drying the hydrolyzed leather
sludge for a longer time at a lower temperature.

This  use  for  leather meal has good economic prospects.  The poultry
feed market in 1975 amounted to over 26,000 tons.  If  all  this  feed
were  to  contain  6  percent  of  leather  meal, almost 1,600 tons of
leather meal could be used in this single application annually.   This
is considerably less than the 80 thousand tons of chrome leather waste
previously  referred  to  as  being  annually  available in the United
States.

In view of the similarity between leather  meal  and  meat  scrap/bone
meal in respect to protein quality, it seems likely that leather meal,
free  of  dioxins,  should  sell  at  about  the  same  price  as meat
scrap/bone meal.  Recent price quotations show  that  meat  scrap/bone
meal   (50  percent  protein) sells for a little over $250 per ton.  On
this basis, leather meal, containing  as  it  does  about  65  percent
protein, should sell for about $325 per ton.  Leather meal today sells
for only $102.50 to $108 per ton.

Air Pollution

The major potential source of air particulate matter from a tannery is
from hide buffing operations.  However, most tanneries control this by
wet  scrubbing.   Scrubber  water is generally combined with the total
waste stream.  Several tanneries are adding  buffing  dust  to  sludge
derived from liquid waste treatment for disposal.

In addition to process sources, tannery boilers can be a source of air
pollution.   With  proper design and maintenance of gas- and oil-fired
boilers, there should be no emission  problems;  however,  with  coal-
fired boilers, fly ash emissions are a problem.  Fly ash emissions can
be  kept  to  a  minimum  with  proper  design  and  operation.   Dust
collection equipment may be used to  further  control  air  pollution.
Wet  scrubbers or electrostatic precipitators are capable of providing
in excess of 98 percent removal of the fly ash.  If a wet scrubber  is
used,  the  waste  dust  slurry  can  be  discharged to the wastewater
treatment system.  Fly ash  from the electrostatic precipitators can be
combined with the dewatered sludge for disposal.

Sulfide  is  the  other  potential  air   pollutant   of   consequence
originating  from  leather  tannery  wastes.   The  sulfide content of
tannery wastes must be reduced and  maintained  at  a  low  level  for


                                 253

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biological  treatment systems to work, to protect the health and lives
of workers exposed to leather tanning wastewaters, and to minimize the
potential for air pollution from any waste treatment system.

Imposition of BPT, BAT, BCT, NSPSr PSES, and PSNS will not create  any

fr^f^a^ial   *lr  P°llution  Problems.   However,  small  amounts  of
volatile organic compounds  may  be  released  to  the  atmosphere  by
aeration systems in biological treatment.                  «»P"ere  cy

Noise


Noise levels associated with wastewater treatment and control both in-

plant and at end-of-pipe are of no material significance as a specific

tannLgS?acm£es? ^ in°rease in the «»**«* noi^ levels in leather
                                254

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                              SECTION IX

        EFFLUENT REDUCTION ATTAINABLE THROUGH THE APPLICATION
         OF THE BEST PRACTICABLE CONTROL TECHNOLOGY CURRENTLY
              AVAILABLE—EFFLUENT LIMITATIONS GUIDELINES
GENERAL
The effluent limitations which were required to be achieved by July 1,
1977, are based on the degree of effluent reduction attainable through
the application of the Best Practicable Control  Technology  Currently
Available  (BPT).   The  BPT  technology  is  generally based upon the
average of the best existing performances by plants of various  sizes,
ages  and  unit  processes  within  the industry.  This average is not
based upon a broad range of plants  within  the  leather  tanning  and
finishing  industry,  but  has  been  derived  from performance levels
achieved by  exemplary  plants.   In  industrial  subcategories  where
present  control  and  treatment practices are uniformly inadequate, a
level of control higher than any currently in place may be required if
the technology to achieve this level can be practicably applied.

BPT  emphasizes  not  only  treatment  facilities  at   the   end   of
manufacturing  processes, but includes control technologies within the
process itself, if such in-plant control technologies  are  considered
to be normal practice within an industry.

In  establishing BPT effluent limitation guidelines, EPA must consider
several factors, including:

     1.   the manufacturing processes employed by the industry;

     2.   the age and size of equipment and facilities involved;

     3.   the engineering aspects of application of various types
          of control techniques;

     4.   the cost of achieving the effluent reduction resulting
          from the application of the technology; and

     5.   non-water quality environmental impact  (including
          energy requirements).

The BPT regulations promulgated by EPA on April  9, 1974  (39 FR  12958)
were  remanded  by  the  United  States  Court   of Appeals in Tanners'
Council of America v. Train, 540 F.2d  1188  (4th  Cir. 1976).  The Court
held, among other things, that: 1) the Agency's  basis  for  technology
transfer  from  the  meat  packing industry to the leather tanning and
finishing industry was not supported by  the  record,  and  2)   EPA's
                                  255

-------
 consideration  of  seasonal variability in effluent concentrations and
 tne need for cold climate adjustments was inadequate.
 MANUFACTURING PROCESSES
 As indicated in earlier sections, there  are  differences  in  tanning
 processes  which  result  in  varying  raw waste characteristics.  The
 Agency has recognized these variations  by  establishing  seven  major
 industry subcategories for effluent limitations.
 AGE AND SIZE OF EQUIPMENT AND FACILITIES

 As  indicated  in  Section  IV  of  this  report,  no significant data
 substantiate the claim that tannery age or  size  justifies  different
 o"!^n^  limit
-------
substantial tannery  waste.   It  also  allows  a  certain  degree  of
positive  control  of the treatment parameters if necessary because of
waste characteristics, loadings, or ambient conditions.

It must be noted that low solids aerated lagoons are not considered to
be equivalent to this  BPT  technology  since  these  systems  perform
poorly  during  the  winter months in northern climates.  Plants using
these systems will be required to upgrade their  treatment  facilities
to  achieve  the  BPT  effluent  limitations  on  a  consistent basis.
Extensive data now in the record also show that,  for  the  pollutants
regulated  by  BPT,  winter climate does not affect the performance of
properly designed and  operated  extended  aeration  activated  sludge
systems.   These systems have been demonstrated in the leather tanning
and finishing industry and technology transfer from  meat  packing  or
any other industry is no longer required.

Development of the Limitations

The  pollutants controlled by this revised regulation include the same
pollutants controlled by the  remanded  BPT  regulation,  specifically
BOD5, TSS, oil and grease, pH, and  (total) chromium.  The discharge of
these pollutants is controlled by mass effluent limitations  (kg/kkg or
Ibs  per  1,000  Ibs of raw material).  The Agency calculated the mass
limitations using demonstrated effluent concentrations, average  water
use  data  for  the  individual subcategories  (see Section V), and the
appropriate variability factors to establish maximum  monthly  average
and maximum day values.  Since the mass effluent limitations are based
on flow, these values vary among the subcategories.

Sixty  months  of  operating  data from the activated sludge system at
tannery no. 47 has been statistically analyzed,  excluding  data  from
two brief periods of upset.  Based upon this analysis,  EPA established
the  maximum  average  concentrations  for  a   30-day   period  for the
parameters regulated under BPT as follows: BOD5 - 90 mg/1, and  TSS   -
145  mg/1.   Results  of   analysis of operating data from the Berwick,
Maine POTW  (excluding data from  the  initial   start-up and  operator
familiarization   period   and   periods   of   upset   or  mechanical
difficulties) serve as the basis of limitations for oil and  grease   -
25  mg/1,  and   (total) chromium -3 mg/1.  The  effluent concentrations
listed above are the same  for all  subcategories,  and  therefore  the
differences in average water use  (gallons/pound of hide) determine the
differences in mass effluent limitations.

The    30-day  maximum  effluent  concentrations  presented   above  are
approximately 1.5 times greater than the  long-term average   for  these
parameters,  as  observed  at tannery no.  47.   The variability analysis
of this data indicated that the ratio of  maximum  daily concentration
to  maximum  30-day   average concentration is  approximately  2.0.  This
ratio  was used to calculate the mass effluent   limitations   reflecting
the  maximum  value   for   any   one  day.   It  is noteworthy  that these


                                  257

-------
 effluent  concentrations  were  achieved  on   a   year-round   basis-

 necessary!  Varianoe  **  Winter  °Pe"tio"   in  «" cH»a?ee it no^

 ENGINEERING ASPECTS OF CONTROL TECHNIQUE APPLICATION

 The  specific level of technology defined as BPT is practicable because
 SiS h^thVann?£Y tnaaatfy already practice it;  other  industries
 with high  strength  wastes  use  it  also.   Data from tannery no  47
 (subcategory No. 3)   and  the  Berwick,  Maine  POTW,  which  receives

        er°ma-  5°
 for  theBTefauenr-         ^"*** «o.  4, served as thbas
 tor  the  BPT  effluent  concentrations.   Performance of the treatment
 system at plant no. 253  (described  in  section  VII)  supports  thlse
 limitations,  since  it  achieves  effluent  levels  well  below thole

 "
 acceedpLs*  mtsT-   ^  ve^etable  Banning  plns  have
 identical  to  ?££   W^h require effluent concentrations virtually
 identical  to  those  noted  above.    The   Hartland, Maine POTW  which
 treats more than 90  percent  tannery  wastewater,  achieves  effluent
  Fiae-101  *" •  ^nerallV  l««r  tha   thos   notd abve
 (Figure 32).  Differences in raw waste  loads among  subcateqories  can
activatedn^nf ^-^ ^^^ ^signed coagulation-sedimtion and
activated sludge units.  Transfer of technology from other  industries
such as meat packing, is no longer  necessary  to  es?abUsh  emuln^
limitations  for  leather  tanners.  For the other direct discharaers
waste control and treatment  is  uniformly  inadequate? and  required
transfer   of   BPT   technology  and  performancl  to  the reSlna
subcategories.   Most of the existing biological treatment   sys^ms  in
the  industry are inadequate.  For example, some of the plants^ Tl) do
              euiPment  necessary  to  be  oerae          '
e^   S  e?uPment  necessary  to  be  operated  as  high'  solids
extended  aeration  activated  sludge;   (2)  are  overloaded activat^


As noted in the  discussion  in  Section  VII,  high  solids  extended
:ssr ^^t^g:^ovtfs^
oraej   For  tannery wastii treatlVwIth
?Lurf fo  trea*ment caPac^y and should thus represt a ™ximUm"ost
figure for  any  tannery.  Some of the important design factors are:
                                258

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200i
175-
SLUDGE BULKING
(HIGH FLOW)
                                               SLUDGE  BULKING(YOUNG  SLUDGE)
                                               AND SAND FILTER START-UP
              Figure 32.  Average Monthly Final Effluent  Concentrations
                          of BOD5^ TSS, and Chromium  (Total)  from  an
                          Activated Sludge System  in  a  Northern  Climate
                          (Hartland, Maine POTW)
                                         259

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          Equalization             Detention:   36 hours
                                     at  design  flow
          Primary  Sedimentation    Overflow Rate:  29 m3/d/m2
                                      (700 gpd/ft2)
          Aeration Basin F/M       0.05-0.1
            Ratio

          Mixed Liquor             6000-10,000 mg/1
            Suspended Solids  (MLSS)

          Sludge Age               20-30 days

          Oxygen Delivery          2.5 kg/kg BOD5 in influent
                                     to basin
          Nutrient Balance:        Carbon: Nitrogen:
                                    Phosphorus - 100:5:1
          Secondary Clarification  Overflow Rate:  8  m3/d/m2
                                     (200 gpd/ft2)

The importance of diligent operation  has been demonstrated in at least
two cases.   An activated sludge system at Tannery No.  237 in Minnesota
                                                     .      n    n
 as  Tsf  ma/1   to* ^  "^ ?«"****"™  *lch  varied  from  as   high
 m^o  I    9  4.-      S  10W as 8'8  mg/1'  Bending upon the experimental
 mode of operation.   During the  first  year  (1976)   of  operation of  a

        fi e ,:
IoD5°fffl°f .time1'^Utvi?tter °P«*«ti»3 skills nave maintained avlrage
BOD| effluent quality below 80 mg/1, except for periods of operational
difficulties  (i.e., inoperative  clarifiers,  etc.).   Therefore   the
basic  feasibility  of the activated sludge process and the imwrtancf
of operational control have been firmly demonstrated.       importance
COST AND EFFLUENT REDUCTION BENEFITS

EPA expects that the total capital investment necessary to upgrade the
effluent* limita"3'^ ^  18  direct.  dfschargers  not  achieving  BPT
costs for all of these plants will increase by^^S^llion^er^Sr6
Achievement   of   proposed   BPT  effluent  limitations  wil!  remove
approximately 54 million pounds per year  of  conventional  pollutant!
                                 260

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   300
   250
   200
o   150
o
z
o
o
L_   100
y.
u.
bJ
    50
                                            PRIMARY B SECONDARY CLARIFIERS
                                           "OUT OF OPERATION
PRIMARY
CLARIFIER
OUT OF
OPERATION
                                                                       SLUDGE
                                                                       BULKING
            DJFMAMJJ  ASONDJ  FMAMJ  JASONDJFMA

           76"77'                           '78*                          '79*
                   Figure 53   Average Monthly BODc  & TSS  Effluent Concentration

                               from an Activated Sludge  System in a Northern Climate

                               (Berwick, Maine POTW)
                                          261

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                                                                o
                                                                PU
             K)
NOUVaiN30NOO
                        262

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(BOD5,  COD,  TSS,  and  Oil  and  Grease), 284,000 pounds per year of
chromium, 374,000 pounds per year of sulfide, 100,000 pounds per  year
of  TKN,  and  significant  quantities  of  other  toxic pollutants in
leather tanning and finishing wastewaters.  EPA  believes  that  these
effluent reduction benefits outweigh the associated costs.

NON-WATER QUALITY ENVIRONMENTAL IMPACT

Unrecovered  waste  products  removed  from tannery discharges or from
processing steps within the tannery take the form of  general  tannery
solid   wastes  or  waste  sludges  from  treatment  facilities.   EPA
estimates that the proposed BPT effluent limitations  will  contribute
an  additional  22,000 metric tons per year of solid waste in the form
of sludges  from upgraded wastewater treatment systems.  The major non-
water quality impact of these wastes is the increased  burden  on  ^the
land  to  accept  their disposal.  Waste trimmings and hair from hides
are presently recovered as by-products.  Recovery and reuse of  chrome
in  some tanning operations will substantially reduce chrome levels in
waste sludge produced by the treatment facility.   In  addition,  this
will  reduce  the  potential release of toxic chrome due to the use of
dewatered sludge at  landfills.   In  all  cases,  however,  dewatered
sludges  from chrome tanneries need separate handling at disposal sites
in  order to avoid any potential difficulties.   Proper landfill siting
and operation will minimize the impact of  tannery  waste   disposal  on
the   land.   See  Section VIII for a discussion of how RCRA will impact
upon  the handling and disposal of tannery  solid  wastes.

EPA has  estimated that the energy  required  by  a  typical  plant  to
achieve  BPT  effluent  limitations   is approximately  1 percent of the
total energy consumed for production  purposes.   This estimate  is based
upon  the total energy used by the industry from  all  fuel   sources  for
production  purposes as documented in  the  1972  Census of Manufacturers.
The   bulk   of  this  increased  energy usage is  for  aeration equipment
operation.

APPLICATION OF BPT EFFLUENT LIMITATIONS

 1.    If a tanner processes hides  in more  than  one   subcategory  (e.g.,
cattlehides and  shearlings), the effluent limitations  should be  pro-
rated based on the percentage of  the  total hide  weight being  processed
 in each subcategory.

 2.    The production  figure  recommended  for applying these  limitations
 is the daily average production  of the maximum 30  consecutive  days.

 BPT EFFLUENT LIMITATIONS

 Based  on  the   rationale  outlined   above, mass  effluent limitations
 (kg/kkg or lb/1000 Ib)  for  the  seven  subcategories established for the
 leather tanning  industry are presented  in Table 40.


                                  263

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                                 Table 40

                         BPT EFFLUENT LIMITATIONS
  Subcategory One  -  Hair  Pulp/chrome Tan/Retan-Wet Finish
 Pollutant or
 Pollutant Property
                     BPT  Effluent  Limitations
               Maximum  for   Average of  daily
               any one  day   values for  30
               	consecutive davs
  Mass Units - kg/kkg  (or lfc/10QQ m of raw matieria1
 BOD5
 TSS
 Total Chromium
 Oil and Grease
 PH
               7.0
              11.2
               0.24
               2.0
 3.5
 5.6
 0. 12
 1.0
 Within the range of 6.0 to 9.0 at all times.
 Subcategory Two - Hair Save/Chrome Tan/Retan-Wet Finish
Pollutant or
Pollutant Property
                     BPT Effluent Limitation^
              Maximum for   Average of daily
              any  one day   values  for 30
                             consecutive
 Mass Units - kg/kkg  for ihxmnn  ib) of  raw
BOD5
TSS
Total Chromium
Oil and Grease
PH
              8.2
             13.4
              0.28
              2.2
4. 1
6.7
0. 14
1.1
Within the range of 6.0 to 9.0 at all times.
                                 264

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Subcategory Three - Hair Save/Non-Chrome Tan/Retan-Wet Finish
Pollutant or
Pollutant Property
                    BPT Effluent Limitations
              Maximum for   Average of daily
              any one day   values for 30
             	consecutive days
 Mass Units - kg/kkg  (or lb/1000 Ib) of raw material
BOD5
TSS
Total Chromium
Oil and Grease
pH Within the
6.0
9.6
0. 20
1.7
range of 6.0 to
3.0
4.8
0.10
0.83
9.0 at all times.
Subcategory Four - Retan-Wet Finish
Pollutant or
Pollutant Property
                    EPT Effluent Limitations
              Maximum for
              any one day
Average of daily
values for 30
consecutive days
 Mass Units - kg/kkg  (or lb/1000  Ib) of  raw  material
BOD5
TSS
Total Chromium
Oil and Grease
pH
              2.6
              4.2
              0.086
              0.70
  1.3
  2. 1
  0.043
  0.35
Within the range of 6.0 to 9.0 at all times.
                                  265

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 Subcategory Five - No Beamhouse
 Pollutant or
 Pollutant Property
                     BPT Effluent Limitations
               Maximum for   Average of daily
               any one day   values for 30
                                       consecuti
                                         d<
  Mass Units - kq/kkg (or lb/1000 Ib)  of raw
 BOD5
 TSS
 Total Chromium
 Oil and Grease
 PH
               5.0
               8.0
               0. 17
               1.4
 2.5
 4.0
 0.083
 0.69
 Within the range of 6.0 to 9.0 at all times.
 Subcategory  Six  -  Through-the-Blue
Pollutant or
Pollutant Property
                     BPT  Effluent  Limitations
              Maximum  for   Average  of  daily
              any one  day   values for  30
                            consecutive days
 Mass Units - kg/kkq  (or lb/1000 Ibl of raw
BOD5
TSS
Total Chromium
Oil and Grease
PH
              4.0
              6.6
              0. 14
              1. 1
2.0
3.3
0.068
0.56
Within the range of 6.0 to 9.0 at all times.
                                 266

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Subcategory Seven - Shearling
Pollutant or
Pollutant Property
                    BPT Effluent Limitations
              Maximum for   Average of daily
              any one day   values for 30
               	consecutive days
 Mass Units - kg/kkg  (or lb/1000 Ib) of raw material
BOD5
TSS
Total Chromium
Oil and Grease
PH
             20. 8
             33.6
              0.70
              5. 8
10.4
16.8
 0.35
 2.9
Within the range of 6.0 to 9.0 at all times
                                   267

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                              SECTION X

       EFFLUENT REDUCTION ATTAINABLE THROUGH THE APPLICATION OF
       THE BEST AVAILABLE TECHNOLOGY ECONOMICALLY ACHIEVABLE—
                   EFFLUENT LIMITATIONS GUIDELINES

GENERAL

The effluent limitations which must be achieved by July 1,  1984,  are
not  based  on an average of the best performance within an industrial
category.  Instead, they are  based  on  the  very  best  economically
achievable control and treatment technology employed by a point source
within  the industrial category or subcategory, or by another industry
from which  technology  is  readily  transferable.   BAT  may  include
process  changes  or  internal controls, even when not common industry
practice.

Best available technology economically achievable (BAT) emphasizes in-
process  controls,  as  well  as  control  or   additional   treatment
techniques  employed  at  the  end  of  the  production  process.   In
developing BAT effluent limitations EPA also considered:

     1.   the manufacturing processes employed;

     2.   the age and size of the equipment and facilities involved;

     3.   the location of manufacturing facilities;

     4.   process changes;

     5.   the engineering aspects of the application of various  types
          of control techniques;

     6.   the cost of achieving the effluent reduction resulting  from
          application of the technology; and

     7.   non-water quality  environmental  impact   (including  energy
          requirements).

The   BAT   technology   level   considers   those  processes  control
technologies which at the pilot plant, semi-works, and  other  levels,
have  demonstrated  sufficient  technological performance and economic
viability to justify investing in such facilities.  BAT represents the
highest degree of  demonstrated  control  technology   for  plant-scale
operation,  up  to  and  including  "no discharge" of  pollutants where
feasible.  The costs of this level of waste  control   are  defined  by
top-of-the-line  of current technology, subject to limitations imposed
by economic and engineering feasibility.   Technical   risk  may  exist
with   respect   to  performance  and  certainty  of   costs  and  some
                                 269

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                                                 «d  adaptation  before
 MANUFACTURING PROCESSES,. AND SIZE, AGE AND LOCATION OF  FACILITIES

 The processes  employed  in  different  sized  tanneries  within   earh






 PROCESS CHANGES







 isolation  and  collection  for  trea^enr^ °% ^:?lant   waste  stream
 the  recommended   effluent   limitaSons"   ^  facilltate  achievement of
 considered    such   chanaes  and   l^  •   ®wei:o"s   tanneries   have
 experimental  work  has teln conductedL
IDENTIFICATION OF BAT TECHNOLOGY
sedimentation)   and  Level
                                 270

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sludge system with nitrification) technologies are the basis  for  BPT
effluent  limitations.   Additional  technologies  considered  BAT are
presented below.

In-Plant Control and Preliminary Treatment

     Level 1 - Water conservation and reuse to reduce flow
                  (all subcategories)
             - Stream segregation for preliminary treatment
                  (subcategory nos.  1, 2, 3, 6, and 7)
             - Ammonia substitution in deliming
                  (subcategory nos.  1, 2, 3, and 6)
             - Chrome recovery and reuse
                  (subcategory nos.  1, 2, 5, 6, and 7)
             - Sulfide liquor reuse followed by catalytic oxidation of
                 residual sulfide  (subcategory nos.  1, 2, 3, and 6)
             - Fine screening of segregated streams  (all subcategories)

     Level 2 - Flue gas carbonation and sedimentation for
                 beamhouse wastewaters  (subcategory  nos. 1, 2, 3, and  6)

A schematic diagram of these technologies for all seven  subcategories
is  presented  in  Figures 4 through 8  (Section VII).  The end-of-pipe
technologies which follow are applicable to all subcategories   (Figure
9).

End-of-Pipe Treatment

     Level 5 - Addition of powdered activated carbon (PAC)
                  to upgrade extended aeration-activated
                  sludge  (Level 4)

     Level 6 - Multimedia filtration

     Level 7 - Granular activated  carbon columns

     Level 4A - Alternative Technology  - Physical/chemical treatment

Table   41  tabulates  the long term performance of BAT technologies  for
each subcategory,  starting with  raw waste loads and  continuing  through
segregated stream in-plant control and  preliminary treament,  combined
stream   end-of-pipe   primary  and   secondary biological treatment,  and
advanced waste  treatment.

The Agency considers  physical/chemical  treatment  (Level 4A   in   Figure
9), an  alternative technology for  direct dischargers, enabling  them to
achieve an  effluent quality   equal to that produced through  Level  6
 (multi-media filtration).  This  technology  can be applied after  Level
3  by direct dischargers.  The existing  biological treatment  systems of
direct  dischargers which exhibit poor performance can be upgraded with
physical/chemical treatment  to achieve the  desired effluent quality.
                                  271

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                    "**? 1O**S m P«dicated on  demonstrated  flow
                                           ££ =,
 DEVELOPMENT OF  BAT EFFLUENT LIMITATIONS

 BAT Reduced Flow
 EPA  analyzed  the log-normal distribution of the wastewater flow data
 for each subcategory to determine  the  geometric  mean  »„*   ?  *  ,
                                =="s        £•* ~
 osof                                     Ascribed  above


         flow.rate c^puted for each subcategory was then compared to
                                         The ke              °
                                       1

rates employed to evaluate BA?' technology? SUmma"ZeS the reduc^ "ow
                             272

-------
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                               Table 42
             SUMMARY OF REDUCED SUBCATEGORY FLOWS FOR BAT
                    Total Number                  Number of Plants
                    of Plants      Reduced Flow   Operating at
                    ReDortina Flow aal/lb (1/kcr)    Reduced Flow
One
Two
Three
Four
Five
Six
Seven
31
12
16
8
14
2
3
3.5
3.7
2.7
1.3
2.3
2.5
11.0
(29)
(31)
(23)
(11)
(19)
(21)
(92)
11
1
4
2
5
1
1
Raw Waste Loads

The mean values for wastewater flow (gal/lb of raw material)   and  raw
waste  loads   (kg/kkg  raw material) reflect the geometric mean of the
log-normal distribution for each parameter.  Subcategory Six  (Through-
the-Blue)  required  a   different   approach   because   of   limited
information.  Raw waste loads for each pollutant parameter relating to
this  subcategory  were  derived by subtracting from subcategory no. 1
raw waste loads the subcategory no. 4 raw waste loads, since  through-
the-blue  plants are exactly the same as hair pulp, chrome tan, retan-
wet finish plants  (subcategory  one),  but  without  retan-wet  finish
operations  (subcategory four).

In  computing  the  raw  waste  concentrations  to reflect the reduced
flows, the pollutant load measured in kg/kkg remained constant.   This
was  done  because  while  available  data for this industry  does show
trends in pollutant reduction, these data do not conclusively confirm
that  reduced  water  contact  with  the product concurrently produces
reduced pollutant loads.  With a constant pollutant load and  a reduced
flow per unit of production, the  calculated  pollutant  concentration
(mg/1)  predicted  by  this  methodology is greater for each  parameter
than the BPT values.  The BAT raw waste characteristics are   shown  in
the  second  column  of Table 41, which provides a comparison with the
current average subcategory waste concentration listed  in  the  first
column.   These  results  represented  the  expected average  raw waste
characteristics used in the engineering analysis of BAT technology.

BAT Treatment  Technology

EPA developed the BAT effluent limitations in building block  fashion,
basing  pollutant control levels on BPT technology  (primary treatment,
secondary biological treatment).  Individual unit treatment   processes
included  as   a part of in-plant control and preliminary treatment are


                                 281

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 discussed  in  section  VII  and  are  identified    (above)   as   BAT
                Y, EP?'   Althou9h  Plants  in  the   industry have used
             treatment  processes,  the  combination  of  all  of   the
 processes utilized for this regulation has not been  demonstrated.

 Starting  from  raw  waste  loads   (lbs/1,000 Ibs) determined for each
 ^v^ory, including pr°ven flow red«<*ions, the performance of each
 of the unit treatment processes was applied to reduce these  loads  in
 the  appropriate  sequence  (Level  1  and 2) for the segregated waste
 «M ???*•• rV^* St^ ln thlS analvsis Portrayed  in Table «fwas to
 utilize industry data discussed in Section VII on the  proportions  of
 flow   and   pollutant  loads  separately  attributable  to  beamhouse
 operations and tanyard,  retan-wet  finish  operations,  so  that  the
 effect   of   segregated   stream  pretreatment  technologies  can  be
 subsequently established.    The  raw  waste  load  flow  (gll/lt?  and
 Sect?orvii^d  '^'T^ lbl  Portions  (summarized 'in Table fSf
 f? £?/•»!      applied  to BAT raw waste loads for each  subcategory
 (labeled  -Raw  Waste  Load  with  Reduced flow" in Table U1)  to yield
 separate flow (gal/lb)  and pollutant loads (lb/1,000 lb)  for these two
 f reap3' 2nd caiculated concentrations (labeled '-Raw Beamhouse Stream"
           anard  tr631"" in Tafcle »-   As  an  example,  subcategory
 toTable35
      Beamhouse:
      Tanyard:
                     3.5  gal/lb x 0.4  = 1.4 gal/lb
                     3.5  gal/lb x 0.6  = 2.1 gal/lb
 Similarly,  BAT  raw waste  load BOD5  would be segregated as follows:
      Beamhouse:
      Tanyard:
                     62.3  lb/1000  lb  x  0.65  =  40.5  lb/1000  lb
                     62.3  lb/1000  lb  x  0.35  =  21.8  lb/1000  lb
Remaining parameters were caluclated  in the   same  manner.    The   "Raw
Beamhouse  Stream"  mass  loadings  were  then   subjected  to  Level  1
technology (sulfxde oxidation) to completely  remove sulf ides  and  level
2 technology  (flue gas  carbonation-sedimentation)  to  reduce  excels
I  InT Vr  e.n ^ n0tSd ^der "Percent Removals' For Treatment levels
     ?    .:  Beamhouse"  in Table 35.  For the  same subcategory  No   1
example,  the  raw  beamhouse  stream  would  be reduced  by  sul?lde
residuals:      **  flUG ^ Carbonation efficiencies to th^f ollowing
     BOD5
     Sulfide:
               40.5 lb/1000 lb x  (1.0-0.6) = 16.2 lb/1000 lb
               2.47 lb/1000 lb x  (1.0-1.0) = 0.0 - complete removal
Remaining
resulting
           parameters  were  calculated  in  the  same  manner.    The
            wastewater   characteristics   (lb/1,000  lb  -  calculated
                                                Beamhouse  Stream" "f
           tohereova    o
substitution  as  discussed  in Sectiovil
                                 282

-------
under "Percent Removals For Treatment Levels 1 and 2 - Tanyard." Again
for the subcategory No. 1 example, the raw  tanyard  stream  chromium,
ammonia, and TKN would be reduced as follows:

     Chromium: 2.9 lb/1000 Ib x  (0.8) = 2.32 lb/1000 Ib captured
               2.9 lb/1000 Ib x  (1-0.8) = 0.58 lb/1000 Ib discharged
     Ammonia:  3.98 lb/1000 Ib x  (1-0.67)  = 1.33 lb/1000 Ib discharged
               3.98-1.33 = 2.65 lb/1000 Ib removed by substitution
     TKN:      (6.8 - 2.65) lb/1000 Ib = 4.15 lb/1000 Ib

No   reductions   were  made  for  other  parameters.   The  resulting
wastewater characteristics  (lb/1,000 Ib -  calculated  concentrations)
are presented under "Treated Tanyard Stream" of Table 41.

The  next pretreatment technology applied is coagulation-sedimentation
of combined streams  (Level 3) which  is  a  part  of  BPT  technology.
Influents  to  combined  stream pretreatment were calculated by adding
the flow  (gal/lb) and  mass  loadings   (lb/1,000  Ib)  under  "Treated
Beamhouse  Stream"  and  "Treated  Tanyard  Stream"  to yield "Level  2
Primary Influent." For the subcategory No. 1 example, flows were added
as follows:

     Treated Beamhouse flow + Treated Tanyard flow = Combined
          flow to Level 3
     1.4 gal/lb  + 2.1 gal/lb =3.5 gal/lb

Pollutant loadings were calculated as follows:

     Beamhouse + Tanyard = Combined load to Level 3
     BOD5:    16.2 lb/1000  Ib + 21.8 lb/1000 Ib = 38  lb/1000 Ib
     Ammonia:  —            + 1.33 lb/1000 Ib = 1.33 lb/1000 Ib
     Chromium: —            + 1.58 lb/1000 Ib = 0.58 lb/1000 Ib
     Sulfide:  0.0           +                 =0.0

It is noteworthy to compare the water use and pollutant mass  loadings
of  this column  of Table 41 to the first column of Table 41, "Existing
Average Raw Waste Load." Application of Levels 1 and 2  technology  to
BPT  systems,  accomplish  major  reduction in the waste load treated by
BPT technology  (Level  3 and Level 4).   For  example,  in  subcategory
one, flow is  reduced by approximately  25 percent; BODJ5 load reduced by
approximately 40  percent;  TSS  load  reduced  by  approximately  45
percent; COD  load reduced  by approximately  75  percent;   and   ammonia
load  reduced by  approximately  67 percent.  It is  on this basis that
engineering estimates were  made  of  the  reduced   long-term   average
treated  effluent  concentrations  as   a result of the addition of  in-
plant control and preliminary treatment  (Levels 1 and 2) as a part  of
BAT  technology.   The  starting points of these engineering estimates
were  the  BPT   effluent   limitations   that  were  based   upon   plant
performance   (see  Section IX).   EPA estimates conservatively that  the
long-term final  effluent concentration  for BODJ5 will be  reduced  from
60  m/gl  to  40 mg/1; TSS will be reduced from 95 to  60, where effluent


                                  283

-------
  eterdn    bh                V  tO  1;   COD  Concentration  was
 determined  by  the  relationship  between  COD  and  BODS (Fiaure 1» -

 ammonia  removal by nitrification will be improved from nil to 10   J/i


 determined gTtJS"7  aC*iev*A *" Plant <">•  253;  TKN concentration was
 «h^f 2 f by.the approximate 4:1 ratio  to  ammonia  generally  noted
              .


             oftheles
                                                          ,

 related  to the  improved  TSS performance expected  at  thi   level"  phenol









 BOD5),   were   not  precisely  calculated  through   use   of  availahii
                                                                   »



Engineering   analysis   established  the  performance  of  additional
     a



                                284

-------
nitrification  by  biological  treatment  is  improved  and  where the
performance of plant no. 253 approaches this concentration without the
influence of PAC; TKN concentration will be reduced from 40 mg/1 to 20
mg/1 in keeping with the 4:1 ratio of to ammonia; and phenol  will  be
reduced  from  0.25 mg/1 to 0.1 mg/1 by enhanced biological treatment,
with  this  concentration  being  achieved  by  well  run   biological
treatment systems in the petroleum refining industry and in some cases
by plants in the leather industry.

Suspended  solids  remaining  in  BAT  OPTION  TWO effluents were then
treated through a system of multi-media  filtration  transferred ^from
numerous  other  industrial  and  municipal applications.  The primary
treatment  accomplished  by  multi-media  filtration  is  control   of
suspended  solids,  including  residuals  of  insoluble chromium.  EPA
estimates that TSS concentrations will be reduced by approximately  35
percent  from  25  mg/1  to 16 mg/1, where consistently lower effluent
concentrations of 10 mg/1  have  been  noted  in  other  applications;
chromium  will be reduced by an amount similar to TSS from 0.5 mg/1 to
0.33 mg/1, where effluent concentrations as low as 0.17 mg/1 have been
reported in the leather industry  (see Table 37)  without  the  use  of
filtration.   The  literature  notes  that  application  of filtration
technology  also  removes  BOD  probably  associated  with  TSS.   EPA
estimates  that  approximately 30 percent of the BOO5 will be removed,
from 20 mg/1 to  14 mg/1.  The COD concentration associated  with  this
reduction  is  determined  by the COD to BODJ3 relationship  (see Figure
3) .  In concert with BODj> removal, a small reduction in oil and grease
will be accomplished, from  10 mg/1 to 6 mg/1; effluent  concentrations
as  low  as  5  mg/1  have been reported.  It is also estimated that  a
small removal of TKN concentration will occur,  from  20  mg/1  to  15
mg/1;  this  is  due  to  the removal of residual proteinaceous solids
 (TSS).  No further reductions are made in  either  ammonia  or  phenol
because  biological  treatment  does  not  occur  in  filtration.  The
resulting effluent quality  (Table 41) was the  basis  for  BAT  Option
Three - Level 6.

Finally, the performance of granular activated carbon  (GAC) columns in
pilot  plant and additional limited industrial application was applied
to  the effluent  quality resulting from BAT Option  Three  -  Level  6,
with  the  resulting  final effluent quality  (Table 41) serving as the
basis  for  BAT  Option Four  -  Level   7.    The   final   effluent
concentrations   were  based  largely  upon  reported concentrations in
other applications with similar treatment preceding GAC columns.

The mass effluent limitations  presented in  Table  43  for  the  seven
subcategories  are  based on BAT Option Three - Level 6.  EPA selected
this option because it  provides  significant  removal  of  the  toxic
pollutants  of   concern in  the  leather  tanning industry  (primarily
phenol and substituted  phenols, and chromium and other  heavy  metals)
by   in-plant    control,    pretreatment,  and  end-of-pipe  treatment.
Although the Act does not require a balancing  of  costs  against  BAT
effluent   reduction  benefits,  the  costs  of  the technology options


                                  285

-------
 ssssr
                                          .tl


                                                 S£i

 optimal*0"3 ^^ °peration and  "-aintenance  procedures mly  not  be


 EPA considers  physical/chemcial  treatment  technology (Level «A)  an

 L^eT 6°r dM r^d^Char9erS t0 Pr0<3uce an *«l«ent quality equal  to
 or foll^ina M  f ^ls=h«gers can apply this technology after Level 3
 or following biological treatment to achieve BAT effluent quality.


 trL^' SamPlf bef°re  C6aSing  °Peration-  "ad  physical/chemical
 an Sf? * ^  Pla°e  WhiCh achieve<3 l°«er effluent concentrations for
 all pollutant parameters (both indicator and  toxic  ixxLlutan^  ^








 Data Variability


 Long-term performance  is the basis   for  all  of the reductions and


 rss  ^s-«:rjs2sr.s S£sr% snsiH
Table 43 shows the BAT effluent limitations as mass  units  
-------
procedure was COD.  For the BAT effluent limitations, residual COD was
computed from the BOD5 to COD relationship  (Figure  3)   presented  in
Section VII.

REGULATED POLLUTANTS

The BAT effluent limitations proposed for the leather tanning industry
focus on three major groups of pollutants:

1.   Non-toxic,   non-conventional   pollutants.     The    non-toxic,
non-conventional  pollutants  limited  by BAT (ans NSPS) include total
Kjeldahl nitrogen  (TKN), ammonia, and sulfide.  As noted below,  these
pollutants  serve  as  "indicator" pollutants for the removal of toxic
pollutants, except for sulfides.   These  pollutants  are  subject  to
numerical limitations expressed in Ibs per 1000 Ibs of raw material.

2-   Toxic pollutants.  The toxic pollutants expressly controlled  for
direct  dischargers in each subcategory are phenol and chromium, which
are subject to numerical limitations expressed in Ibs per 1000 Ibs  of
raw  material.   Since  the EPA has adopted the control of "indicator"
pollutants as the basis for controlling toxic pollutants, no  effluent
limitations  are  recommended  for  any  toxic  pollutants  other than
chromium and phenol.

3.   Indicator  pollutants.   The  difficulties  of  toxic   pollutant
analyses  have  prompted  EPA  to  propose  a new method of regulating
selected toxic pollutants.  Historical data and inexpensive analytical
methods are limited for certain toxic pollutants.  Therefore,  EPA  is
proposing  numerical  limitations  on "indicator" pollutants for which
there is substantially more data; these include BOD5,  COD,  TSS,  oil
and  grease,  TKN, ammonia,  (total) chromium, and  (total) phenol.  The
data available to EPA revealed that when  these  indicator  pollutants
were   controlled,   the   concentrations  of  toxic  pollutants  were
significantly lower than when indicator  pollutants  were  present  in
high  concentrations.  Moreover, the treatment systems  existing in the
industry were designed for removal of conventional and nonconventional
pollutants.

EPA's consideration of "indicator"  limitations  was  brought  to  the
attention   of  Congress during the formative  stages  of  the Clean Water
Act of  1977.  At  that time, EPA was examining several  techniques  to
alleviate   the   difficulties  of  lengthy  and  expensive  analytical
procedures.   The  proposed alternate "indicator" limitations serve that
purpose.   This method of toxics regulation obviates  the  difficulties,
high  costs,  and delays fo monitoring and analyses that would result
from limitations  solely on the toxic pollutants.

Quotations  recently obtained  from a number of analytical  laboratories
indicate   that   the cost of each wastewater analysis for organic toxic
pollutants  ranges between  $650 and $1,700, excluding sampling  costs.
Even  if   cost   were not such a  factor, the availability of laboratory


                                  287

-------
 ths   stubeganW°Ulf ^fuT6?  •*Ut*»»l  constraints.   When
 sophisticated  Sment  could  oerfo™  te?hnician  ""ng  the  mos?
 analysis  in  an   8-h^  work  dav   ^rl, °nly  °ne  complete  organic
 commercial  laboratories  in  the"  n£?JS V6r' t?ere were only ^oiit  15
                            n    e  n
  capability  to  perform  these  Lalysef   Todaf thf^   SU"icient
  commercial  laboratories known to EPA  which  hfve  ^!    ar«.f^out 5°
  perform  these analyses  and <-he ™™vL   . ™  nave  the  capability  to
  such capability alsTfncreases?  ^ci^c^S^8^ bee""6 *"""?
                                  ^j-a.j.^ieiicy aiso nas been improving.
  be effectively controlled  by' limitation o 6S^hat.th?se  Pollutants can
  even  though  the  toxics   (other  than  oheno?  ln^icator. Pollutants
  expressly regulated by numerica^limitations         chromium) are not




  inorganic  compounds.   An  indicator  for 9?h»  c°mP°unds,  and  the
  compounds is "total  phenol"  as  mtaanrS  h     substituted  phenolic
  method  (KAAP) .    This  mpth^rl  ™ measured ^bV  the  4-aminoantipyrine

                            .
TKN,  and  ammonia)  are controlled  *h?« pollutants  (especially  COD,
resistant  to  rapid  bLdegrfdatfon   wUl
                              "
                                      w
 Similarly,  EPA  concludes  tha   contro   of  z?nr  ? *f  aS   wel1'
 copper  is accomplished by a sDecif£>  if™T«.J?-      '     d' nicke1' an
 by control of TSS as an indicator  ^uitant     °" tOtal chromi™. ™
 Many of the toxic organic compounds  are  known  to  be   resistant
 ^S"1, cS«rsL,?s,  s-insssf f;r     ^  » :  s™
                                          "
                        »
determined  by  a  traditional  and  ^a"  ^e /apidly   and   reliably
method.            traditional  and  relatively inexpensive analytical
                                       non-conventional pollutant  of
pollutants are therefore l
                                288

-------
It should be noted that some of  the  indicator  pollutants,  such  as
BODS,  COD,  TSS  and oil and grease, are classified as "conventional"
pollutants under Section 304 (a) (U) of the Act or proposed regulations.
Where conventional pollutants  serve  as  "indicator"  pollutants  for
toxic  pollutants,  BAT  limitations  for  these  pollutants have been
established to  assure  installation  of  waste  treatment  technology
adequate  for  the  removal  of  toxic pollutants.  In such cases, the
"indicator" limitations on conventional pollutants will be established
regardless of the BCT test.  Furthermore, some of the "indicators" are
nonconventional   pollutants.    These   non conventional   "indicator"
pollutants   will  not  be  subject  to  economic  and  water  quality
modifications under Sections 301 (c) and  (g) of  the  Act.   Exceptions
may  be justified.  A specific discharger may attempt to show that his
waste stream does not contain any of the toxic pollutants that  a  BAT
effluent  limitation  on  a  conventional  or  non-conventional  toxic
"indicator" was designed to remove.  If this  can  be  shown,  then   a
limitation  on  a  conventional  pollutant would be subject to the BCT
cost test, and a limitation on a non -conventional pollutant  would  be
subject to requests for modifications.

The  Agency  is  also  considering  the  possibility  of  establishing
numerical limitations  (either  in concentration or mass units) for  the
following  toxic  pollutants:  phenol   (by  GC/MS  methods), 100 yg/1:
2,4,6-trichlorophenol,  50 pg/1;  pentachlorophenol,  25 pg/1;   lead,
250  pg/1; zinc, 250 pg/1; cyanide,  500
The  numerical  limitations under consideration  for phenol  (100  pg/1) ,
2,4,6-trichlorophenol  (50  pg/1) , and pentachlorophenol   (25 pg/1)   are
based  upon  the  structure,  known chemical properties, and available
treatability data for these compounds as developed by Strier.107  These
are  considered to be 30 day average concentrations based upon  combined
activated sludge - powdered activated carbon biological treatment. 108

The  numerical limitations  being considered  for lead   (250 pg/1) ,   zinc
 (250 ng/1) ,  and  cyanide  (500  jjg/1) are based upon their treatability
as  indicated by  data  developed  during  the  sampling  and   analysis
program  for  this  industry.   Strier «s  limitations  developed  were
higher108: lead and zinc - 500  pg/1, and cyanide -  1,000 H9/1-   Strier
developed these limitations utilizing data  from  a number of industrial
sources  and projecting different  treatment schemes.'  The  data  now
available    in   this   industry,   however,    supports   the   lower
concentrations .

Comments and additional data  are  welcomed on   all  of  these  toxic
pollutant limitations being considered  by the Agency.
                                  289

-------
  ENGINEERING  ASPECTS OF THE APPLICATION OF BAT







  situation,   some  of  the  process^  ar*  X d "?*£* Waste treatn,ent
  beamhouse  operations  and  tanv*^  „     grouped  by  function  into
  these different operations varies ?„ n^" tlons'  /he wastewater from

                                      '
                                                      ----   -
 pollutantmixes and loadng.   eSlgne    for  ^pecxfic,  less  variable

                C°lleCtion of »«tewater  from the beamhouse and tanyard
                                m
 essential to achieve th recmended
 with a beamhouse and tanvard   in arir-       -
 recovery  and  reuse  of process chfmt^? '  ^  concePt  facilitates
 have expressed the  samfopfnion with reqard  tr^?fS ^st^ s™™**
 management  and  control.   A  tarn^rv  mf^      effective  wastewater



 and effective treatment system.        9   d  operating   a  consistent

 Another  method  of  pollutant reduction employed by  the  industrv i* i-o

properly designed  and operated? C-Laritier  and  the  fHter   unit  are
                                290

-------
Cost-effective  removal  of  oil  and  grease  is best accomplished in
preliminary  treatment   or   end-of-pipe   primary   treatment   with
well-maintained  and properly designed catch basins or clarifiers with
skimmers.     Industries    such    as    leather    tanning,    which
characteristically  produce  high  oil and grease in their wastewater,
concentrate their removal efforts  in  primary  treatment.   Moreover,
"secondary"  treatment technologies will work better when high oil and
grease loadings are avoided.  Equipment fouling and overloads  to  the
secondary  treatment system are associated with excessive influent oil
and grease loading.  Many toxic pollutants which are  not  soluble  in
water  tend  to  be included in fats, oils, and greases, and therefore
can be reduced by separating or skimming the floating oil  and  grease
from primary clarifiers.

Ammonia reduction in leather tanning wastewaters has been achieved by:
1)  end-of-pipe  extended  aeration  technology;  2) physical-chemical
treatment; and 3)  substitution  of  magnesium  sulfate  for  ammonium
sulfate  in  the  deliming  process  of the tanyard operations.  Using
magnesium sulfate directly reduces  the  ammonia  content  of  tannery
wastewater  by 67 percent, but increases chemical cost.  One vegetable
tannery has indicated leather  quality  problems  resulting  from  the
substitution   while   other  plants  did  not  report  problems.   As
substantial body of literature, highlighted in Section VII,  indicates
that substitution for ammonia is feasible.

Most  tanneries select a chemical alternative strictly on the basis of
cost.  However, waste treatment cost for ammonia removal must  now  be
included  in  cost  considerations  because of the BAT effluent limit.
Reduced costs of ammonia removal support the use of an alternative  to
ammonium sulfate.  Ammonia substitution is then justified as a part of
the basis for BAT effluent limitations.

Wastewater  treatment  technologies  recommended for achieving the BAT
limitations are producing low ammonia concentrations in  the  effluent
from  leather  tanneries  and  from  industrial plants with comparable
waste streams, such  as  rendering  plants.   To  achieve  substantial
ammonia  reduction,  the recommended technology requires proper design
and carefully controlled operation.   Long-term  operating  data  from
shearling  Tannery No.  253, which operates a Carrousel oxidation ditch
activated sludge system  (subcategory no. 7), is the basis for transfer
of this nitrification technology to the remaining subcategories of the
leather tanning and finishing industry.  With  the  exception  of  the
initial  startup period, and periods of upset including April and May,
1979, this plant has produced consistently low effluent concentrations
of ammonia and TKN during both summer and winter months, as  shown  in
Figures  35 and 36.

Data     from    a   full-scale   nitrifying   high   solids   extended
aeration-activated sludge system in other  subcategories  is  not  yet
available  for comparison.  EPA believes that with  in-plant control of
ammonia  to reduce the higher masses  (lb/1,000 Ib)   and  concentrations


                                 291

-------
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for purely economic  reasons,  with  the  added  benefit  of  improved
wastewater  quality.   Chrome recovery and reuse, which is approaching
standard practice, is an example of such  decision-making  within  the
industry.   Other  process changes include sulfide reuse and recovery,
and substitution for ammonia in deliming.  Reduction of water use  can
be  accomplished  through  conservation and recycle systems  (including
pasting frame wash water), and other  process  modifications  such  as
those  highlighted in Section VII of this document.  The total mass of
regulated pollutants  for  all  direct  discharges  removed  from  BPT
effluent  levels  by  this  BAT technology option would be as follows:
610,000  Ibs/year  of  BOD5;  2,000,000  Ibs/year  of  COD;  1,100,000
Ibs/year  of  TSS; 710,000 Ibs/year of oil and grease; 21,000 Ibs/year
of chromium  (total); 1,670,000 Ibs/year of TKN;  620,000  Ibs/year  of
ammonia;  5,100  Ibs/year  of  phenol   (total); and 26,000 Ibs/year of
sulfide.  EPA estimates the total mass of toxics pollutants  discharged
would be as  follows: 640 Ibs/year of volatile organics;  80C  Ibs/year
of  base/neutral  organics;  2,000  Ibs/year of acid organics; and 380
Ibs/year of  the inorganic pollutants exclusive of chromuim.

NON-WATER QUALITY ENVIRONMENTAL IMPACT

EPA has found that a  significant  portion  of  the  toxic   pollutants
removed  from tannery wastewater remains intact in the solids that are
removed from the wastewater.  These solids are  subsequently disposed
in  landfills  and  other  disposal  sites  with variable controls, as
indicated in Sections VII and VIII.  The impact of  such  disposal  is
the  primary non-water quality concern resulting from the BAT effluent
limitations.   EPA  estimates  that  achievement   of   BAT   effluent
limitations  will   generate  an  additional 41,000 metric tons/year of
sludges  from BAT   treatment  technology  as   applied  by   all   direct
dischargers.

Energy  consumption for  waste  treatment  will   increase  in order to
achieve the  proposed limits.   However,  the   wastewater  control  and
management   practices   implemented to  reduce  the total  flow may  result
in a net energy  saving, compared to the energy expended to  achieve BPT
effluent  limitations.   Reduction  in   pumping  and   other   operations
associated   with  wastewater   movement   and   control  will reflect  less
energy  use.

BAT EFFLUENT LIMITATIONS

The effluent concentrations and  associated  mass  loadings   listed  in
Table   41   are  long-term  averages.  Variability  has been  factored  into
the maximum month and  maximum  day  effluent   limitations   presented  in
Table  45.
                                  297

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                                  Table  45

                         BAT  EFFLUENT LIMITATIONS
  Subcategory One - Hair Pulp, chron* Tan, Retan-Wet Finish
  Pollutant or
  Pollutant Property
                      BAT Effluent Limitations
                Maximum for   Average of daily
                any one day   values for 30
                              consecutive days
Mass Units - kq/kkq
BOD5
COD
TSS
Oil and Grease
Total Chromium
TKN
Ammonia
Phenol
Sulfide (mg/1)
PH Within the
. -~— „. 	
(or lb/1000 Ib)
2.*
. 1
9f»
.5
2^
. 5
OQ 1
• J I
0.053
2-*
. 3
0*7 ~»
. 77
Of\ -t c
.015
0.0
range of 6.0 to
of raw material

0.61
5.8
0.70
0.26
0.015
0.66
0.22
0.0043
On
.0
9.0 at all times.
 Subcategory Two - Hair Save/chrome Tan/Retan-Wet Finish
 Pollutant or
 Pollutant Property
                     BAT Effluent: Limitations
               Maximum for   Average of daily
               any one day   values for 30
                             consecutive
  Mass  Units  -  kg/kkq  for  1b/1000 lh)  of ..... ^
BOD5
COD
TSS
Oil and Grease
Total Chromium
TKN
Ammonia
Phenol
Sulfide (mg/1)
PH
                  2.3
                 10.0
                  2.6
                  1.0
                  0.053
                  2.4
                  0.81
                  0.016
                  0.0
0.65
6.2
0.74
0.28
0.015
0.69
0.23
0.0046
0.0
Within the range of 6.0 to 9.0 at all times.
                                 298

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Subcategory Three - Hair Save/Non-Chrome Tan/Retan-Wet Finish
Pollutant or
Pollutant Property
                    BAT Effluent Limitations
              Maximum for   Average of daily
              any one day   values for 30
             	consecutive days
 Mass Units - kg/kkg (or lb/1000 Ibl of raw material
BOD5
COD
TSS
Oil and Grease
Total Chromium
TKN
Ammonia
Phenol
Sulfide  (mg/1)
PH
                 1.6
                 7.3
                 1.9
                 0.70
                 0.039
                 1.8
                 0.60
                 0.012
                 0.0
0.47
4.5
0.54
0.20
0.011
0.51
0.17
0.0034
0.0
Within the range of 6.0 to 9.0 at all times
Subcategory Four - Retan-Wet Finish
Pollutant or
Pollutant Property
                    BAT Effluent Limitations
              Maximum for   Average of daily
              any one day   values for 30
              	consecutive days
  Mass  Units  -  kg/kkg  (or  lb/1000  Ib)  of  raw material
 BOD5
 COD
 TSS
 Oil and Grease
 Total Chromium
 TKN
 Ammonia
 Phenol
 Sulfide (mg/1)
 pH
                  0.81
                  3.5
                  0.91
                  0.35
                  0.018
                  0.84
                  0.28
                  0.0056
                  0.0
     Within the  range of  6.0  to  9.0
0.23
2.2
0.26
0.10
0.005
0.24
0.081
0.0016
0.0
at all times
                                  299

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 Subcategory Five - No Beamhouse
 Pollutant or
 Pollutant Property
                     BAT Effluent Limitatinns
               Maximum for   Average of daily
               any one day   values for 30
                             consecutive davs
 BOD5
 COD
 TSS
 Oil and  Grease
 Total Chromium
 TKN
 Ammonia
 Phenol
 Sulfide  (mg/1)
 pH
1.4
6.2
1.6
0.60
0.034
1.5
0.49
0.010
0.0
                                    0.40
                                    3.8
                                    0.46
                                    0.17
                                    0.0096
                                    0.43
                                    0.14
                                    0.0029
                                    0.0
Within the range of 6.0 to 9.0 at all times.
Subcategory Six - Through-the-Blue
Pollutant or
Pollutant Property
                    BAT Effluent Limitation^
              Maximum for   Average of daily
              any one day   values for 30
                           .consecutive davs
BOD5

COD
TSS
Oil and Grease
Total Chromium
TKN
Ammonia
Phenol
Sulfide (mg/1)
PH Within
1C
. D
6n
. 8
10
. 8
0.67
0.035
If
. 6
0.56
0.011
0.0
the range of 6.0 to

0. 44
V • *T •?
4.2
0.50
0.19
0.010
0.47
0.16
0.0031
0/\
.0
9.0 at all times
                                300

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Subcategory Seven - Shearling
Pollutant or
Pollutant Property
                    BAT Effluent Limitations
              Maximum for   Average of daily
              any one day   values for 30
                  	consecutive days
 Mass Units - ka/kkg  (or lb/1000 Ibl of raw material
BOD5
COD
TSS
Oil and Grease
Total Chromium
TKN
Ammonia
Phenol
Sulfide  (mg/1)
pH
                 6.7
                29.8
                 7.7
                 2.9
                 0.16
                 7.4
                 2.4
                 0.049
                 0.0
Within the range of 6.0 to 9.0
    1.9
   18.0
    2.2
    0.83
    0.046
    2.1
    0.69
    0.014
    0.0
at all times
                                  301

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                              SECTION XI

                EFFLUENT REDUCTION ATTAINABLE BY BEST
              CONVENTIONAL POLLUTANT CONTROL TECHNOLOGY


INTRODUCTION

The   1977   amendments   added   section  301(b) (4)  (E)  to  the  Act,
establishing "best conventional pollutant  control  technology"  (BCT)
for  discharges  of  conventional  pollutants from existing industrial
point sources.  Conventional pollutants are those defined  in  section
304(b) (4)  -  BOD,  TSS,  fecal  coliform  and pH - and any additional
pollutants defined by the Administrator as  "conventional."   On  July
28,   1978,  EPA  proposed  that COD, oil and grease, and phosphorus be
added to the conventional pollutant list (43 Fed. Reg. 32857).

BCT is not an additional limitation, but replaces BAT  for the  control
of   conventional  pollutants.   BCT  requires  that   limitations  for
conventional  pollutants  be  assessed  in  light  of  a  new   "cost-
reasonableness"  test,  which  involves  a  comparison of the cost and
level of reduction of conventional pollutants from  the  discharge  of
POTW's  to  the  cost and level of reduction of  such pollutants from  a
class or category of industrial sources.  As part of its review of BAT
for certain "secondary" industries, EPA proposed methodology for  this
cost  test.   (See 43 Fed. Reg. 37570, August 23,  1978).

EPA   is  proposing that the conventional "indicator" pollutants, which
are used as "indicators" of control  for toxic pollutants,  be  treated
as  toxic   pollutants.   In  this  way,  effluent  limitations will be
established for the conventional indicator pollutants  at  BAT  levels,
and   the  limitations will not have  to  pass the  BCT  cost test.  When  a
permittee,  in a specific case, can show that  the waste stream  does not
contain  any  of  the   toxic  pollutants  that   a  conventional  toxic
"indicator"  was  designed  to remove,  then the  BAT  limitation on that
conventional  pollutant  will no longer be treated as  a  limitation on   a
toxic pollutant.   The technology   identified  as  BAT  for  control of
toxic pollutants  also  affords removal of  conventional  pollutants  to
BAT  levels.   As noted  below, these  effluent  levels passed the  BCT cost
test, and therefore, are  also designated as  BCT  effluent levels.

APPLICATION OF  BCT  METHODOLOGY

EPA  applied the BCT cost  test  to the costs  associated with  the removal
of conventional pollutants  in  the leather  industry.   In  the first  step
 in  the  analysis,  EPA calculated the size  of  an average  plant for  each
 subcategory based upon the  actual production   of  plants  with  direct
discharge.   No  plants existed  in subcategory no. 6 (through-the-blue),
and   the  average  plant  size  for indirect dischargers  was used.   Raw
waste load data (Tables 6-12)   for  each  subcategory  determined   the
amount  of wastewater and pollutant^load generated by each plant for an


                                  303

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                                                                   °
                                                            "
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      6.
    EFFLUENT  LIMITATIONS



The pollutants  controlled by this regulation  include the  conventional



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bas; o  A  ,aj-  Fua.j.urants COD ana oil and crrease-    Tho  TJ^T.  4-^^v^^-i	


Table
                                 304

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-------
 Subcategory One - Hair Pulp/Chrome Tan/Retan - Wet Finish
 Pollutant or                  BCT Effluent Limitations
 Pollutant Property      Maximum for   Average of daily
                         any one day   values for 30
 —	.	consecutive days

  Mass Units  - kq/kkg (or lb/1000 lb)  of raw material

 BODS                        91               f\ *i
    —                        *•  •               0.61
 COD                        9.5               5.8
 TSS                        2.5               0.70
 Oil and  Grease             0.91              0.26
 pH         Within the range  of  6.0 to  9.0 at all times.
Subcategory  Two  -  Hair  Save,  Chrome Tan,  Retan-Wet Finish
Pollutant or                   BCT  Effluent  Limitations
Pollutant Property      Maximum  for    Average  of  daily
                        any one  day    values for  30
	.     	__	__	consecutive days

 Mass Units - kq/kkcf  for lb/1QOO lb) of  raw material

BOD5                       ?  q               A  CC
   —                       £• 3               0.65
COD                        10.0               62
TSS                        2.6               £^4
Oil and Grease             1.0               Q  28
PH        Within the range of 6.0 to 9.0 at all times.
                                 306

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Subcategory Three - Hair Save/Non-Chrome Tan/Retan-Wet Finish
Pollutant or
Pollutant Property
                    BCT Effluent Limitations
              Maximum for
              any one day
Average of daily
values for 30
consecutive days
 Mass Units - kg/kkg (or lb/1000 Ib)  of raw material
BODS
COD
TSS
Oil and Grease
pH Within
1.6
7.3
1.9
0.70
the range of 6.0 to
0.47
4.5
0.54
0.20
9.0 at all times.
Subcategory Four - Retan-Wet Finish
Pollutant or
Pollutant Property
                    BCT Effluent Limitations
              Maximum for
              any one day
Average of daily
values for 30
consecutive days
 Mass Units - kg/kkg (or lb/1000 Ib) of raw material
BOD5
COD
TSS
Oil and Grease
                 0.81
                 3.5
                 0.91
                 0.35
       0.23
       2.2
       0.26
       0.10
PH
Within the range of 6.0 to 9.0 at all times.
                                 307

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 Subcategory Five - No Beamhouse
 Pollutant or
 Pollutant Property
                      BCT  Effluent  Limitations
               Maximum  for   Average of  daily
               any one  day   values for  30
               	—	consecutive davs
  Mass Units - kq/kkq (or lb/1000 Ib)  nf ^w materia
 BOD5
 COD
 TSS
 Oil and Grease
 PH
                  1.4
                  6.2
                  1.6
                  0.60
 0.40
 3.8
 0.46
 0.17
Within the range of 6.0 to 9.0 at all'tirnes.
 Subcategory  Six  -  Through-the-Blue
Pollutant or
Pollutant Property
                     BCT Effluent Limitations
               Maximum for   Average of daily
               any one day   values for 30
                             consecutive
 Mass Units - kg/kkq  (or lb/1QOO Ibl of raw material
BOD5
COD
TSS
Oil and Grease
PH
                  1.5
                  6.8
                  1.8
                  0.67
0.44
4.2
0.50
0.19
Within the range of 6.0 to  9.0 at all times.
                                308

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Subcategory Seven - Shearling
Pollutant or
Pollutant Property
                    BCT Effluent Limitations
              Maximum for
              any one day
Average of daily
values for 30
consecutive days
 Mass Units - kg/kkg (or lfc/1000 Ib) of raw material
BOD5
COD
TSS
Oil and Grease
PH
                 6.7
                29.8
                 7.7
                 2.9
       1.9
      18.0
       2.2
       0.83
Within the range of 6.0 to 9.0 at all times.
                                  309

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                             SECTION XII

                   NEW SOURCE PERFORMANCE STANDARDS
INTRODUCTION

The basis for new source performance standards  (NSPS)   under  Section
306  of  the Act is the best available demonstrated technology (BADT).
New plants have the opportunity to design the best and most  efficient
leather  tanning  processes  and  wastewater  treatment  technologies.
Therefore, Congress directed EPA to  consider  the  best  demonstrated
process   changes,   in-plant   controls,  and  end-of-pipe  treatment
technologies which reduce pollution to the maximum extent feasible.  A
major difference between NSPS and BAT is that the Act does not require
evaluation of NSPS in light of the BCT cost test.

EPA has selected control and treatment technology Level  6   (including
multi-media  filtration) as the basis for NSPS because it provides for
the maximum feasible removal of  toxic  pollutants  of  concern.   The
Aqency  rejected  Level  7  (GAC columns) because EPA believes that GAG
columns are too expensive and sophisticated for use in this  industry.
Although  EPA believes that physical-chemical treatment  (Level UA) may
be a viable option, it rejected  this  technology  option  because   of
technical   and  cost  questions  regarding   its  application  to  raw
wastewaters  different   from  those  of  the  retan-wet  finish  plant
 (Subcategory  Four)  where  it was installed.  However, a new plant may
well overcome cost and technical questions  with  careful  design  and
pilot  plant evaluation.

NSPS EFFLUENT LIMITATIONS

Since  the control and treatment technology basis for NSPS is  the  same
as that  established  for  BAT (Level  6),  the methodology used  to develop
the  effluent limitations,  the engineering aspects of this  technology,
and  the  numerical  effluent  limitations  (Table 43) are  also the same.
                                  311

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                             SECTION XIII

                        PRETREATMENT STANDARDS

GENERAL

The  effluent  limitations  that  must be achieved by new and existing
sources in the leather tanning and finishing industry  that  discharge
into  a POTW are termed pretreatment standards.  Section 307(b)  of the
Act requires EPA to promulgate  pretreatment  standards  for  existing
sources   (PSES)  to  prevent  the  discharge  of pollutants which pass
through, interfere  with,  or  are  otherwise  incompatible  with  the
operation  of  POTW's.   The  1977 amendments to the Act also requires
pretreatment for pollutants, such as heavy  metals,  that  limit  POTW
sludge  management  alternatives,  including  the  beneficial  use  of
sludges on agricultural lands.  The legislative history  of  the  1977
Act  indicates that pretreatment standards are to be technology-based,
analagous to the  best  available  technology  for  removal  of  toxic
pollutants.   The  general pretreatment regulations  (40 CFR Part 403),
which  served  as  the  framework  for  these  proposed   pretreatment
regulations  for  the  leather  tanning and finishing industry, can be
found in 43 Fed. Reg. 27736-27773  (June 26, 1978).

Consideration was also  given  to  the  following  in  establishing  a
pretreatment standard:

     1.   the manufacturing processes employed by the industry;

     2.   the age and size of the equipment and facilities involved;

     3.   the location of manufacturing facilities;

     4.   process changes;

     5.   the engineering aspects of the application of
          pretreatment technology and its relationship
          to POTW;

     6.   the cost of application of technology in
          relation to the effluent reduction  and other
          benefits achieved from such application;   and

     7.   non-water quality environmental impact  (including
          energy requirements).

PRETREATMENT STANDARDS FOR EXISTING SOURCES  (PSES)

Manufacturing  Processes, and  Size, Age, and Location of Facilities

The  processes  employed  in   different  size tanneries  within  each
subcategory are basically similar.  Furthermore, the factors of   size,


                                 313

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age,  and  processes  employed  do not affect the pretreatment control
technology used and proposed.  Hence these factors were  not  direct^

oT  facil?t?^ernining the *«*«*»«* standard.  A!SO, ?he loc^ion
of   facili       was   not   a  factor  to  be  considered
Process Changes
   -          °Ut  in Section VII< ^direct dischargers should consider
wf^^a  was^ewater  management  and  control  practices  to  reduce
wastewater  volume  and  pollutant loadings, as well as the surcharges
and capital cost recovery paid by  tanneries  discharging  to  POTW?f
This reduction can be achieved by implementing the following measures ":

     1-    Appoint a person  with  specific  responsibility  for  water

          management.   This  person  should have reasonable powers to
          enforce improvements  in  water  and  waste  management  and
          implement better housekeeping practices.        wgement  and


     2.    Determine or estimate water use and waste load strength from
                                                               in   all
          Make  all  employees aware of  good  water management   practices

          and   encourage   them  to apply these  practices.  one practice

          ™ri?? emplo?ee Participation  is  the  elimination of  the
          constantly running hoses observed in some tanneries.

          Recirculate non-contact cooling water,   such  as  that  from
          vacuum driers.


          Segregate waste  streams from each major  in-plant  process
    6.   Use  more  care  in  unloading,  unfolding   and   otherwise

                               pr°cessin^ to minimize salt entry into
    7.   Collect unhairing waste stream,  reduce  pH  to  isoelectric

         point  to  precipitate  dissolved  protein,  and recover the
         protein as a valuable by-product.                recover tne


    8.   Reuse or recover active chemicals from waste streams such as
         Examine tanning formulas  to  determine  if  floats   cap   be

         reduced.     Use  of  hide  processors   and   other  specially
         designed  vessels has  lowered float  volumes,        specially
                                314

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     10.   Provide  regularly  scheduled  maintenance   attention   for
          screening  and  solid  waste handling systems throughout the
          operating day.  A backup screen may be desirable to minimize
          solids entry into the municipal sewer system.

Such practices are feasible and may be economically attractive through
the reduction of municipal water and sewer use charges resulting  from
lower flows and waste loadings.

Pretreatment Technology

Candidate  control technologies for pretreatment are the same as those
considered as  candidate  BAT  technologies  for  direct  dischargers.
These technologies are as follows:

     Level 1 - Water conservation and reuse to reduce flow
                  (all subcategories)
             - Stream segregation for preliminary treatment
                  (subcategory nos. 1, 2, 3, 6, and 7)
             - Ammonia substitution in deliming
                  (subcategory nos. 1, 2, 3, and 6)
             - Chrome recovery and reuse
                  (subcategory nos. 1, 2, 5, 6, and 7)
             - Sulfide liquor reuse followed by catalytic oxidation of
                  residual sulfide  (subcategory nos.  1, 2, 3, and 6)
             - Fine screening of segregated streams  (all subcategories)

     Level 2 - Flue gas carbonation and sedimentation  for
                  beamhouse wastewaters  (subcategory  nos.  1,  2,  3, and  6)

    Level  3 - Primary coagulation-sedimentation of combined  streams
                  (applicable to all subcategories)

Performance of these levels of treatment were described in Section VII
for  the   specific  technology.    Table  41,  presented   in  Section X,
indicates  the   performance  of    these   technologies    for   tannery
wastewaters.     Figures    4    through    9   schematically  showed  the
pretreatment   technology   identified   for    existing   sources   by
subcategory.

Rationale  For The Pretreatment Standard

The   rationale    for   developing   the   pretreatment  standards  rests
primarily  on the concept of controlling  pollutants   which   interfere,
pass  through,   or  are otherwise  incompatible   with POTW treatment
systems  and  sludge  disposal.   See  Section  307(b)  of  the Act  and  EPA's
recently  promulgated   pretreatment   regulations   (40 CFR Part  403, 43
Fed. Reg.  27736-27773  (June 26,  1978).   BOD5,   TSS,   oil  and   grease,
total  chromium,  sulfide,  ammonia,   and   other   toxic pollutants are
present  in sufficient  concentrations  in  the raw waste  from  tanneries
                                  315

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 and Iluigfdisp^al. Wlth  P°tential  Problems  of  Pollutant pass-through

 For this  technology-based  analysis,  EPA  has assumed the following:

      1.   Any  joint municipal-industrial POTW which receives
          leather  tanning  and finishing  wastewater has been
          assumed  to provide primary sedimentation and
          secondary biological treatment including final
          clarification and sludge management.   These
          facilities are assumed to  be properly  designed
          and  diligently operated.

      2.   Analysis of pass-through and upset  relating to POTW has been
          determined up to the point of  wastewater release from
          control of the leather tanning and  finishing plant;
          therefore, specific collection system  circumstances
          may warrant consideration at the local level.

      3.   Local water quality constraints and unique
          operational or sludge disposal problems,
          have not been considered during this engineering analysis.

     4.   Strict adherence to and local enforcement of the
          general prohibited discharge provisions of the
          pretreatment regulation,  and similar provisions
          in local ordinances,  is essential to ensure that
          potential problems of  upset and/or pass-through
          noted below are not permitted to  occur.

Tannery wastewaters  potentially  can  create   or  contribute  to  the
following problems for  a POTW:

     1.   potential problem with future disposal  of sludges
          containing  toxic  pollutants,  especially chromium;

     2.   odors,  facilities corrosion,  very high  dissolved
          oxygen  demand  in  aeration basins  of  biological
          treatment systems, and  hazardous  gas generation
          from  sulfide-bearing wastes;

     3.    wide  fluctuations in pH, and  hydraulic  and
          pollutant loads;

     4.    excessive quantities of hair  and  other  small
          screenable solids;

     5.    high  concentrations of suspended  and settleable
          solids, BOD5, and other pollutants;  and

     6.    pass-through of ammonia nitrogen.
                                316

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The  potential problems listed above can be largely eliminated through
leather tanners1 strict adherence to local  discharge  provisions  and
national  pretreatment  regulations.   Moreover, properly designed and
diligently operated POTW»s can  suitably  treat  leather  tanning  and
finishing wastewater.

The information gathered during this study indicates that the BOD5 and
TSS  found  in  tannery wastewater are amenable to removal by properly
designed and operated activated sludge secondary biological  treatment
systems.   Operating  data from four joint municipal-industrial POTW's
which employ the activated  sludge  process  to  treat  more  than  50
percent  tannery  wastewater  indicates  that  influent  BOD5  and TSS
concentrations, which range from 250 mg/1 to 950 mg/1 and 200 mg/1  to
900  mg/1,  respectively, can be reduced to effluent concentrations of
10 mg/1 to 65 mg/1 and 11 mg/1 to 75 mg/1,  respectively.   The  broad
range  of  influent concentrations did not indicate a sensitivity to a
maximum level  beyond  which  the  wastewaters  were  not  effectively
treated.  However, none of these plants consistently achieved the BOD5
and  TSS effluent concentrations which served as the basis for BAT and
BCT regulations.

Chromium is removed to low effluent concentrations from wastewater  in
POTWfs  which   include  primary  treatment  and  secondary  biological
treatment systems.  Data  from one municipality  indicates that influent
chromium  (trivalent) concentrations, often greater than  100 mg/1,  are
reduced  in  the  final effluent to concentrations of less than 2 mg/1.
Other  POTW data indicate  final effluent concentrations from  1 mg/1  to
as little as  0.1  mg/1.

Chromium  removal occurs in  treatment   systems,  but  POTW's  do not
monitor for chromium as extensively as they monitor for  BOD5  and  TSS.
Alkaline   precipitation   of    chromium   occurs  readily  in primary
clarifiers.   EPA  found no evidence  that chromium interferes   with  the
performance   of  biological  treatment  systems in  use as  secondary
treatment.  Two factors  influence the   chrome   concentration  of  POTW
effluent:   (1)  dilution resulting  from  other wastes entering  the POTW;
and  (2)   removal   occurring  within the   waste treatment   processes.
However,  the presence of carbonates and  improper  pH can substantially
 impair trivalent  chromium removal.  Moreover,  comparison of   observed
 chromium  effluent  concentrations  with those  required by BAT effluent
 limitations  for direct dischargers  indicates that   the  POTW  effluent
 may   contain   higher  concentrations.   With   the  bulk of the chromium
 removed at the individual industrial   sites  by pretreatment  through
 Level  3,  affected  POTW's   will  be able to  improve  upon the effluent
 concentrations  of  chromium  and   approach  the   levels of  chromium
 required   by   BAT.     Consistent  achievement    of    BAT    chromium
 concentrations by the POTW is  one  of the  criteria  for  eligibility  for
 "credits" as  set forth by 40 CFP Part  403.

 A  few  municipalities  have  had   substantial  difficulty   in finding
 acceptable sites for disposal of sludges  containing  large   quantities


                                  317

-------
of chromium.   Pretreatment through Level 3 at the  industrial 
-------
          during   summer  months,  when  rapid  bacterial  uptake  of
          dissolved oxygen can cause release  of  unoxidized  hydrogen
          sulfide.

A  careful  review of the extent of these sulfide-related problems has
led EPA to conclude that national regulation is necessary.   Currently
available  and practicable technology  (catalytic oxidation)  can remove
most if not all dissolved sulfides.  Where a tanner has segregated the
siilfide-bearing beamhouse wastewater for separate catalytic oxidation,
sulfide carry-over  by  the  hides  or  skins  into  tanyard  and  wet
finishing waste streams may require the precipitation of this residual
to  achieve the effluent limitation.  Coagulation with ferric chloride
is an approach available for controlling sulfide in  tanyard  and  wet
finishing  wastewaters.   However, it also is likely that sulfide will
be  liberated  to  the  atmosphere  during  the  acid-based  processes
including  tanning.   Taken  together,  sulfide removal technology and
provision  of  suitable  pH  conditions  can  achieve  a  pretreatment
standard  of   0.0 mg/1   (not  detectable  by the analtyical method for
sulfide) at the point of discharge to the POTW sewer.

Effluent data  from  POTWs  indicate  that  ammonia  nitrogen  passes
through  both  POTW's and separate tannery wastewater treatment systems
which are well designed and operated.  Substitution for ammonia in the
deliming process,  along  with   beamhouse  pretreatment   to  remove   a
substantial  portion  of  the   protein  which  ultimately contributes
substantially  to  ammonia,  should  sufficiently  reduce  the  ammonia
content   of   leather   tanning  wastewaters.    This   should   allow
nitrification  in POTW  biological  treatment  systems   to  be   more
successful in  controlling pass-through of this pollutant.

EPA  has  reviewed  the  proposed pH range of  6.0 to  9.0, with special
regard  for the control of hydrogen  sulfide  gas  evolution  and trivalent
chromium  removal  at  low  values  of pH.   The Agency has  determined  that
for  maximum control  of sulfides in gravity  collection  systems  and POTW
headworks,  and   for  maximum removal  of  trivalent chromium largely in
primary clarifiers,  the  optimum pH range  is  7.0 to  10.0.    Potentially
dangerous evolution  of sulfides can occur below a pH  of  7.0,  and  below
a  pH   of 6.0  potentially inadequate removal of trivalent chromium  can
 occur.    At   pH   greater  than  10.0,   the   potential  may  exist  for
disruption    of    biological    treatment    systems.    Therefore,  the
 appropriate  general  sections  of the regulation have   been  amended   to
 require  pH   no  lower   than   7.0 and  no  higher than  10.0 for  the four
 subcategories which include beamhouse  operations,  and to require  pH no
 lower  than  6.0 and no higher  than 10.0 for  the  retan-wet  finish,   no
 beamhouse,  and shearling subcategories.

 Methodology  Used to Develop PSES Effluent Limitations

 Engineering  analysis developed the PSES effluent limitations using  in-
 plant  control  and  primary  treatment technologies  in building  block
 fashion.   Within the tannery, the beamhouse and tanyard waste  streams


                                  319

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                                                             sss
 ta±rd1 wfste1011/1 Sh°WS.the bre^°«n  of  the  raw  beamhouse  and
 tanyard  waste  streams prior to separate control measures

 Engineering  Aspects of Pre treatment  Technology
 Publicly Owned  Treatment Works       -
                                                and  Relationshic  to
                                                -  Kexationstiip  to

S6Ction' the
                                              associated with leather
taSnninf
  her  ce     enera
chromium precipitate in primary

                    a necessary
                                                                the
                                       to equalization for effective
                                                                s
                               320

-------
sulfhydrates  in  the unhairing process risk catastrophic accidents if
pH is not controlled when segregated wastewaters  are  mixed.   Plants
which do not operate a beamhouse may need lime addition to increase pH
to  a level where effective biological treatment can be maintained, to
minimize corrosion, and  to  reduce  chromium  residuals  to  a  level
acceptable to the POTW.

Effective  fine  screening  (with openings in the range of 0.040 inches
to remove easily separated scraps, fibers, and hair)  was  lacking  at
most  leather  tanning  and finishing plants in the industry.  Without
fine screening, pipes can become clogged and pumps,  clarifier  sludge
rakes,  and  other  related  equipment  at  the  POTW can incur severe
damage.

The Agency recognizes that many plants in  urban  areas  will  require
extensive  planning  and  judicious  use  of  interior floor space and
adjacent land to incorporate pretreatment facilities.  Constraints  on
available  interior  plant  floor  space  and  adjacent land was a key
decision criterion in the pretreatment technology   selection  process.
Moreover,  the  selected  PSES were not as stringent as EPA would have
preferred due to land constraints,

In cases where a number of  plants are located in  close  proximity  to
each  other,  combined  pretreatment  facilities  may  afford  a cost-
effective approach to reduce  both  total  costs  and  costs  to   each
tanner,  minimize  duplication  of  facilities at each plant, and take
advantage of economics of scale.  This  is   likely  to  be   especially
germane  to  sludge  dewatering and transporting equipment,  and to the
identification, development,  and  use  of   hazardous  waste  disposal
sites.

COST  AND EFFLUENT  REDUCTION BENEFITS

Approximately   170   tanneries  currently  discharge to POTW's, and are
thus  subject to pretreatment standards  for  existing sources.  While   a
few   of  these  plants   have   some  wastewater  treatment  in  place, the
following  estimated costs   assume  none.    EPA   estimates  that  total
investment   costs   to  meet proposed  PSES  will  be  approximately $59
million, with  total annual  operating  costs of   about   $21 million,
increasing current operating expenses by  3.0 percent.

EPA   estimates  that  the   total  mass  of regulated pollutants  for all
indirect dischargers removed  from untreated wastewaters  by  this   PSES
technology  option would be as  follows:  2,300,000  Ibs/year of  chromium
 (total);  1,400,000 Ibs/year of   ammonia;   and  1,800,000   Ibs/year  of
 sulfide.    The total mass  of  pollutants not regulated but removed  from
untreated  discharge levels  by  this  PSES technology option would be  as
 follows:   30,000,000  Ibs/year  of  BOD5;  88,000,000 Ibs/year  of  COD;
 46,000,000 Ibs/year of TSS; 8,200,000 Ibs/year  of  oil and grease;   and
 2,500,000   Ibs/year  of  TKN.   EPA estimates the total toxic pollutant
 discharge  would be as follows:  6050  Ibs/year  of   volatile  organics;
 7500  Ibs/year  of  base/neutral  organics;  18,000  Ibs/year   of  acid


                                  321

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                                              llunts  exciusi-
 underlie     efflt u,n?ations19er  ^ the con^^rations which
 Non-Hater Quality Environmental Impact
 The proposed  pretreatment  standard  will  substantially  reduce  the
                                                                 '
                                                         and
th37'°°°  metric *«*« P« year will  be  generated
                                                                  by

concentraionsof toxpollutas11"
                               322

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PSES EFFLUENT LIMITATIONS

Table 48 lists the pretreatment standards for existing sources in each
subcategory.


                               Table 48

                      PSES EFFLUENT LIMITATIONS

Subcategory One - Hair Pulp/Chrome Tan/Retan-Wet Finish


Pollutant or            Maximum       Average of daily
Pollutant Property      concentration concentrations
                        for any one   for 30 consecutive
__	day	days	

                	milligrams per liter  (mg/1)	
Total Chromium                6              3
Ammonia                       136            68
Sulfide                       0.0            0.0
pH       Within the range of 7.0 to  10.0 at all times.
Subcategory Two - Hair Save/Chrome Tan, Retan-Wet  Finish


Pollutant or            Maximum       Average  of daily
Pollutant Property      concentration concentrations
                        for any one   for  30 consecutive
	dav-mg/1	days-mg/1	

                	milligrams per liter  (mg/1)

Total Chromium                 6              3
Ammonia                        138            69
Sulfide                        0.0            0.0
pH      Within the  range of 7.0 to  10.0 at all times.
                                  323

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  subcategory  Three -  Hair  Save.  Non-Chrome  Tan,  Retan-Wet  Finish
  Pollutant or
  Pollutant Property
 Total Chromium
 Ammonia
                         Maximum       Average of daily
                         concentration concentrations
                         for any one   for 30 consecutive
                         ciay-mq/1      days-mg/1

                          milligrams per liter (mg/1)
 PH
          Within the range of 7.0 to 10.0 at all times
 Subcategory Four - Retan-Wet Finish
Pollutant or
Pollutant Property
                                       Average of daily
                         concentration concentrations
                         for any one   for 30 consecutive
                          milligrams per liter
 Total Chromium
 Ammonia
PH
                               o.0
          Within  the  range  of  6.0  to  10.0  at all  times
 Subcategory Five - No Beamhouse
Pollutant or
Pollutant Property
                        Maximum       Average of daily
                        concentration  concentrations
                        for any one    for  30  consecutive
                        day-m/1      days-ma/l
                         milligrams per liter
Total Chromium                  6             3
Ammonia                       + c (•
Sulfide                       ofo            00
PH       Within the range of 6.6 to 10.0 at all times,
                                 324

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Subcategory Six - Through-the-Blue
Pollutant or            Maximum       Average of daily
Pollutant Property      concentration concentrations
                        for any one   for 30 consecutive
 	dav-mq/1	davs-mg/1	

                	milligrams per liter  (mg/1)

Total Chromium                  6              3
Ammonia                        120            60
Sulfide                        0.0            0.0
pH       Within the range of 7.0 to 10.0 at all times.
Subcategory Seven  -  Shearling
Pollutant or            Maximum        Average  of  daily
Pollutant Property      concentration  concentrations
                        for  any  one   for  30 consecutive
	      dav-mq/1      davs-mg/1	

                 	milligrams per liter  (rng/1)

Total Chromium                 6              3
Ammonia                       52             26
Sulfide                       0-0            °-°  .
pH      Within the range of 6.0 to 10.0 at all times.


PRETREATMENT STANDARDS FOR NEW SOURCES (PSNS)

Section 307 (c) of the Act  requires  EPA  to  promulgate  pretreatment
standards   for  new  sources  (PSNS) coincidently with the adoption of
NSPS.  New indirect dischargers, like new direct dischargers, have the
opportunity to incorporate the  best  available  demonstrated  control
technologies   (BADT) including process changes, in-plant controls, and
 end-of-pipe treatment.  New plants can select and locate on a s^t-  to
ensure adequate installation of the treatment system.
                                  325

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  treatmen    scheme  considere     c»        BAt
  dischargers.  The  PSNS technologiefare af  follo^

      Level  1 - water conservation and reuse to reduce flow
              - Stream segregation for preliminary treatment
              - Ammonia substitution in deliming      <*tment
              - Chrome recovery and reuse

              "
              - Fine screening of segregated streams

      Level 2 - Flue gas carbonation and sedimentation
                 for beamhouse wastewaters

      Level 3 - Equalization of combined streams followed by
                 primary coagulation-sedimentation


      Level 4A - Physical /chemical treatment (Chappel Process)




 techno^ies  with  r^pec(f **£**», ^^^L^^^o^es

 As noted  in the rationale for the pretreatment  standard   for

 °US

                                                    to tat
waters.                        ,  and  discharge  direct  to navigable
     EFFLUENT LIMITATIONS

The  general  pretreatment  regulations
                                        .    ,
                                326

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                               Table 49

                      PSNS EFFLUENT LIMITATIONS
Pollutant or
Pollutant Property
           Maximum
           cone en tr at ion
           for any one
           day-mg/1	
Average of daily
concentrations
for 30 consecutive
davs-mg/1	
BOD5
COD
TSS
Oil and Grease
Total Chromium
TKN
Ammonia
Phenol
Sulfide
pH Within the
74
325
84
32
1.8
79
26
0.53
0.0
range of
21
200
24
9
0.5
23
7.5
0.15
0.0
6.0 to 9.0 at all times.
 Equivalent mass  limitations  for  each  subcategory are  as  follows

 Subcategory  One  -  Hair  Pulp/Chrome  Tan/Retan-Wet Finish
 Pollutant or
 Pollutant Property
                  Effluent Limitations
              Maximum for   Average of daily
              any one day   values for 30
             	consecutive days
  Mass Units - kq/kkg (or lb/1000 lb)  of raw material
 BOD5
 COD
 TSS
 Oil and Grease
 Total Chromium
 TKN
 Ammonia
 Phenol
 Sulfide (mg/1)
 PH
                 2.1
                 9.5
                 2.5
                 0.91
                 0.053
                 2.3
                 0.77
                 0.015
                 0.0
        0.61
        5.8
        0.70
        0.26
        0.015
        0.66
        0.22
        0.0043
        0.0
Within the range of 6.0 to 9.0 at all times
                                  327

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  Subcategory TWO - Hair Save/Chrome Tan/Retan-Wet Finish
  Pollutant or
  Pollutant Property
                            Effluent Limitations
                        Maximum for   Average of daily
                        any one day   values for 30
                                      consecutive
  Mass Units  -  kg/kkg  (or  Ih/lQQQ  ib)  Qf
 BOD5
 COD
 TSS
 Oil and Grease
 Total Chromium
 TKN
 Ammonia
 Phenol
 Sulfide (mg/1)
 PH
                           2.3
                          10.0
                           2.6
                           1.0
                           0.053
                           2.4
                           0.81
                           0.016
                           0.0
 0.65
 6.2
 0.74
 0.28
 0.015
 0.69
 0.23
 0.0046
 0.0
          Within  the  range  of 6.0 to 9.0  at all times.
 Subcategory Three - Hair Save/Non-Chrome Tan/Retan-Wet Finish
 Pollutant or
 Pollutant Property
                           Effluent Limitations
                       Maximum for   Average of daily
                       any one day   values for 30
                                     consecutive davs
Mass Units - kg/kkcr (or lb/1000 Ib) nf
BOD5
COD
TSS
Oil and Grease
Total Chromium
TKN
Ammonia
Phenol
Sulfide (mg/1)
PH
                          1.6
                          7.3
                          1.9
                          0.70
                          0.039
                          1.8
                          0.60
                          0.012
                          0.0
                                             :n
0.47
4.5
0.54
0.20
0.011
0.51
0.17
0.0034
0.0
        Within  the  range  of  6.0  to  9.0  at  all  times.
                                 328

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Subcategory Four - Retan-Wet Finish
Pollutant or
Pollutant Property
                  Effluent Limitations
              Maximum for   Average of daily
              any one day   values for 30
                 	consecutive days
 Mass Units - kg/kkg (or lb/1000 lb) of raw material
BOD5
COD
TSS
Oil and Grease
Total Chromium
TKN
Ammonia
Phenol
Sulfide  (mg/1)
PH
                 0.81
                 3.5
                 0.91
                 0.35
                 0.018
                 0.84
                 0.28
                 0.0056
                 0.0
0.23
2.2
0.26
0.10
0.005
0.24
0.081
0.0016
0.0
Within the range of 6.0 to 9.0 at all times
Subcategory Five - No Beamhouse
Pollutant or
Pollutant Property
                  Effluent Limitations
              Maximum for   Average of daily
              any one day   values for 30
              	consecutive days
 Mass Units  -  kg/kkg  (or  lb/1000  lb)  of  raw  material
 BOD5
 COD
 TSS
 Oil and  Grease
 Total  Chromium
 TKN
 Ammonia
 Phenol
 Sulfide  (mg/1)
 PH
                 6.2
                 1.6
                 0.60
                 0.034
                 1.5
                 0.49
                 0.010
                 0.0
0.40
3.8
0.46
0.17
0.0096
0.43
0.14
0.0029
0.0
Within  the range  of  6.0 to  9.0  at  all  times
                                  329

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 Subcategory Six - Through-the-Blue
 Pollutant or
 Pollutant Property
                   Effluent Limitations
               Maximum for   Average of daily
               any one day   values for 30
               	 consecutive days
  Mass Units - kg/kkg (or lb/1000 lb)  of raw materia
BOD5
COD
TSS
Oil and Grease
Total Chromium
TKN
Ammonia
Phenol
Sulfide (mg/1)
PH Within the range
1.5
6.8
1.8
0.67
0.035
1.6
0.56
0.011
0.0
of 6.0 to
0.44
4.2
0.50
0.19
0.010
0.47
0.16
0.0031
0.0
9.0 at all times
 Subcategory  Seven  -  Shearling
Pollutant or
Pollutant Property
                   Effluent  Limitations
              Maximum  for    Average of  daily
              any  one  day    values  for  30
              	   consecutive _days
 Mass Units - kg/kkg  for lb/1000 lb) of raw material
BOD5
COD
TSS
Oil and Grease
Total Chromium
TKN
Ammonia
Phenol
Sulfide (mg/1)
PH
                  6.7
                29.8
                  7.7
                  2.9
                  0.16
                  7.4
                  2.4
                  0.049
                  0.0
 1.9
18.0
 2.2
 0.83
 0.046
 2.1
 0.69
 0.014
 0.0
Within the range of 6.0 to 9.0 at all times
                                 330

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                             SECTION XIV

                              MONITORING
INTRODUCTION

When required  to  carry  out  the  objectives  of  the  Act,  EPA  is
authorized  by  Section  308  to  require  the  owner or operator of a
polluant discharge source to  establish  and  maintain  records,  make
reports,  install  and  use  monitoring  equipment  or methods, sample
effluents and provide such other information as the Administrator  may
reasonably   require.   The  authority  under  Section  308  has  been
frequently used by permit issuers to set  monitoring  requirements  to
"determine  whether any person is in violation" of the requirements of
a permit  or  other  requirements  of  the  Act   (Section  308(a) (2)).
Additionally,  EPA has frequently sought information under Section 308
to aid in developing regulations for many industries.

In these, and perhaps  other  "toxics"  regulations,  EPA  is  setting
monitoring  requirements  for  direct and indirect dischargers for the
purpose of "developing or assisting  in  the  development"  of  future
effluent  limitations guidelines, pretreatment standards and standards
of performance  (Section 308 (a) (1)).  These monitoring requirements are
not  intended  to  supersede  or   duplicate   compliance   monitoring
requirements  set by NPDES permit authorities.  A mandatory monitoring
and analysis program is feasible at this time because  the  costs  for
toxic  pollutant  analyses  have decreased and laboratory availability
and efficiency have dramatically increased  since  the  initiation  of
this study.

MONITORING PROGRAM
                                             •
The  monitoring program included in the proposed regulation will  serve
a number  of  purposes.   First,  the  long  term  data  generated  on
conventional,  nonconventional  and  toxic  pollutants  will allow the
Agency to review and revise,  if necessary, the  proposed  regulations.
Where  data  indicates  that  treatment technologies discharge  effluent
levels different from those in the regulations,  adjustments   will  be
made and the regulations amended.  Second, the data collection program
is  designed  to  permit  the Agency  to  establish express limits on
specific    toxics    of      concern      (i.e.,     pentachlorophenol,
2,4,6-trichlorophenol,   lead,   etc.),  or  alternatively,  establish
statistically valid correlations among "surrogate"   (now  "indicator")
pollutants   and  the  toxic  pollutants  of  concern.   Selection  of
surrogate pollutants would allow identification of a shorter and  less
costly   (in  terms of monitoring expense) list of pollutant parameters
for which plants would be required  to  sample  and  analyze.    Third,
these  monitoring  requirements will combine all major data collection
activities into one reporting mechanism.


                                 331

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       are numerous developments and alternatives potentially available
               monitoring cost for toxic pollutants in addition to  the
 ar^ -f.       »of  surrogates  (indicators)  of  toxic pollutants   A
 specific group or groups within the total  list of toxic pollutants"may
 somelme™^°r ?* la?9e n^ber °f  SamPles nationwide1" may  produce
 Approaches?         SCale  "lth  automate<3  °* similar cost reduction

 The proposed monitoring and analysis program would require  continuous
 tlow  and  pH  monitoring at points of  discharge to POTWs (for indirect
 dischargers)   or   discharge   to   receiving   waters    for  direct
 dischargers).   Plants  which process  more than 3.1 million  pounds plr
 year of  raw material will be required  to collect a  24-hour   composite
 sample once every week (in all cases during a representative periol of
 m^aT"  n^^^^,0^1..^.  ™*«*?_ -  3imilar6p!e^s of
                                                             oil  and
 asr rj£si ss ss
 24-hour composite sample once quarterly (again dSing a representative
 Plants  which  process   less  than  3. 1 million  pounds per year of raw
 material will be required to collect a 24-hour composite  samnle  ™™



                                                                 V
afsohbrt°^en°i'- "^ Pe»talorophenolconcurrt grab sles' musl
also be taken twice per year and analyzed  for cyanide (total™.
All  plants   will  be  additionally  required  to  report  the   total
zsrir ss.
                                                          .
etc.),  and the hourly values of flow and pH for the reriod  of  £^?1
                       .
                               332

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quantitatively specifies the design and operating features of all unit
processes and equipment.

Monitoring  requirements  for  direct dischargers will be effective on
the issuance of a new NPDES permit  or  renewal  or  extension  of  an
existing  permit,  and  will  remain in effect for two years from that
date.   Monitoring  requirements  for  indirect  dischargers  will  be
effective   three  years  from  the  date  of  promulgation  of  these
regulations (or on the earlier  installation  of  technology  to  meet
pretreatment  standards) and will remain in effect for one year.  On a
quarterly  basis,  all  individual  data  points  generated  by   this
monitoring  program must be submitted directly to the Project Officer,
Leather  Tanning   and   Finishing   Industry,   Effluent   Guidelines
Division  (WH-552),  EPA,  U01  M  St.  S.W.,  Washington, D. C.  20U60.
Copies  also  must  be  submitted   to   NPDES   authorities    (direct
dischargers)  and  affected POTWs  (indirect dischargers).  Where these
individual  data  points  are  submitted  for  compliance   monitoring
purposes, duplicate sampling and analyses are not required.
                                  333

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                              SECTION XV

                           ACKNOWLEDGEMENTS


The  program  was conducted by a team of staff members and consultants
of the Midwest Research Institute (MRI),  Minnetonka,  MN,  under  the
direction  of Mr. Robert J. Reid.  Major contributors included Messrs.
R. R. Rich, E. P.  Shea,  Mrs.  Vicki  Moteelall,  Ms.  Janine  Neils,
Messrs. James Spigarelli, Clarence Haile, R. H. Forester, Chris Lough,
Edward  Conway,  J.  R.  Neleigh,  K.  R. Walker, D. Weatherman, J. G.
Edwardsff  R. F  Colingsworth and I. N. Ibraham,  Mrs.  Robin  Raslmussen
and Mrs«,  Mary Weldon.

Contributions  were  also  made  to  this  study  by  the consultants:
Lawrence Rust, Stanley Consultants, Inc., and SCS Engineers, Inc.  The
EPA contractor for the economic impact study, Development Planning and
Research  Associates,  Inc.,  was  also  very  helpful  in   providing
information for use in this report.

Thanks are also due to Mr. David Ertz and Mr. Ralph Oulton of the E.C.
Jordan  Co.,  for  their  final  technical  editorial  review  to this
document.

The cooperation and assistance of the Tanners1 Council of America  was
invaluable  to  this  program  especially in the persons of Dr. Robert
Lollar and Mr. Eugene Kilik, who provided personal time and  attention
during  various  stages  of the data collection process.  The numerous
tannery owners, managers, superintendents and operators who  submitted
information,  opened  their  plants  to  program  staff, and othe?rwise
cooperated are acknowledged and thanked  for their patience and hnlp.

The people in the various offices  of  the  EPA,  of  state  pollution
control  agencies,  and  of  local  POTW and other public agencies or
officials are also acknowledged for their help on this program.

Mr. Barry Malter  of  the  Office  of  General  Counsel  is  specially
acknowledged   for  his  major  contribution  to  the  development  of
technical and legal rationale, and to the integrity and readability of
the  preamble,  regulation,  and  this *  development   document.    Ms.
Margherita  Pryor  also  provided significant editorial improvement to
this document.

Word processing  for this project was performed by  Ms.  Nancy  Zrubek,
with  assistance   from  Ms.  Kaye  Starr and  Ms. Carol Swann.  Their
personal sacrifice and long hours made   possible  the  assembly  of   a
large  volume of written material into a document of high quality  in  a
very short period of  time.   Without  their  efforts,  the  preamble,
regulations, and this development document would not be available.
                                  335

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effort.  Their contributions are gratefully acknowledged?
                               336

-------
                             SECTION XVI
                              REFERENCES

1.         Development  Document  for  Proposed  Effluent   Limitations
          Guidelines  and  New  Source  Performance  Standards for the
          Leather Tanning and Finishing Industry, U.S.   Environmental
          Protection  Agency,  Report  No. 440/1-74-016-a, Washington,
          March 1974.
2.         Leather Facts,  New England Tanners Club, Peabody, MA, 1965,

3.         Personal Communication with P.  Maier,  Dwars,  Heederik  en
          Verhey B.V., the Netherlands.
4.         Quality Criteria for Water,  U.S.  Environmental  Protection
          Agency,  Report  No.  440/9-76-023,  Washington,  D.C., July
          1976.
5.         Proposed  Water   Quality   Criteria,   U.S.   Environmental
          Protection Agency.  44 FR 15926, March 15, 1979.
6.         Benzene.   Draft  Criteria  Document,   U.S.   Environmental
          Protection  Agency.   PB  292421,  Natl.  Tech.  Inf. Serv.,
          Springfield, VA.
7.         Proposed  Water   Quality   Criteria,   U.S.   Environmental
          Protection Agency, 44 FR 43660, July 25, 1979.
8.         Tetrachloroethylene.    Draft   Criteria   Document,    U.S.
          Environmental  Protection  Agency.   PB  292443, Natl. Tech.
          Inf. Serv., Springfield, VA.
9.         Carbon  Tetrachloride.   Draft   Criteria   Document,   U.S.
          Environmental  Protection  Agency.   PB  292424, Natl. Tech.
          Inf. Serv., Springfield, VA.
10.       Toluene.   Draft  Criteria  Document,   U.S.   Environmental
          Protection  Agency.   PB  296805,  Natl.  Tech.  Inf. Serv.,
          Springfield, VA.
11.       Trichloroethylene.    Draft     Criteria    Document,    U.S.
          Environmental  Protection  Agency.   PB  292445, Natl. Tech.
          Inf. Serv., Springfield, VA.
12.       Chloroform.  Draft  Criteria  Document,  U.S.  Environmental
          Protection  Agency.   PB  292427,  Natl.  Tech.  Inf. Serv.,
          Springfield, VA.
                                  337

-------
 13.       Dichlorobenzenes.      Draft    Criteria    Document     o s
           Environmental  Protection  Agency.    PB  292U29, Natl.  Tech"
           Inf. serv.. Springfield,  VA.

 11.       Nitrosamines.  Draft Criteria  Document,  U.S.   Environmental

           Springfield,^?^-    PB   2"™*'   Hat1'   TeCh'   Inf'  Serv-

 15.       1.2-Diphenylhydrazine.    Draft  Criteria   Document,    u S

                                                                       "
 16.        Benzidine.   Draft  Criteria  Document,  U.S.   Environmental
           Protection  Agency.   PB  297918   Natl   T^b    r^f   &
           Springfield, VA.                '                      Serv.,


 17.        3,3|-Dichlorobenzidine.   Draft  Criteria   Document,    u  s
           TPww^ -w-^-^*~«Mk *^.M j__ —. n   •«. _ .   . •                  .            "      *
 18.        isophorone.   Draft  Criteria  Document,  U.S.  Environmental
           Protection  *	    —  	
           *ra.Wucv.uj.uii  Agency.    PB  296798,  Natl.  Tech   Inf  q*>™
           Springfield, VA.                    i«.i.  lecn.  int. Serv.,



 19"        Protection6"  °raft  Criteria  Docuinent'  U.S.  Environmental



 20.        Polynuclear  Aromatic Hydrocarbons.   Draft Criteria Document,

           U.S. Environmental   Protection  Agency.   PB  297926   Natl
           Tech.  Info.  Serv., Springfield,  VA.            ^^^.  Natl.


 21.        ^heno1-.   Dr*ft   Criteria   Document,    U.S.    Environmental
22.       2,4-Dichlorophenol.     Draft   Criteria    Document,     u s

          Environmental  Protection  Agency.    PB  292431,  Natl.  Tech"
          Inf. Serv., Springfield, VA.


23.       Chlorinated  Phenols.    Draft   Criteria   Document,    u.s

          Environmental  Protection  Agency.    PB  296790,  Natl   Tech
          Info. Serv., Springfield, VA.


24.       2,4-Dimethylphenol.    Draft   Criteria    Document,     U.S.
          TPffcTT1* W»X^.*>**M ^*.M. _1_ —. 1   1-* _ _ _ i   . •                              *
                                 338

-------
25.       Pentachlorophenol.    Draft    Criteria    Document,    U.S.
          Environmental  Protection  Agency.   PB  292439, Natl. Tech.
          Inf. Serv., Springfield, VA.

26.       Chromium.   Draft  Criteria  Document,  U.S.   Environmental
          Protection  Agency,   PB  297922,  Natl.  Tech. Info. Serv.,
          Springfield, VA.

27.       Copper.   Draft  Criteria   Document,   U.S.   Environmental
          Protection  Agency.   PB  296791,  Natl.  Tech. Info. Serv.,
          Springfield, VA.

28.       Nickel.   Draft  Criteria   Document,   U.S.   Environmental
          Protection  Agency.   PB  296800,  Natl.  Tech. Info. Serv.,
          Springfield, VA.

29.       Larsen, Bjarne C., "Utilization of  the  Hide  Processor  in
          Reducing  Tannery  Effluent,"  presented  at the 67th Annual
          Meeting  of  the  American  Leather  Chemists1  Association,
          Mackinac Island, Michigan, June 20 through 23, 1971, as part
          of the Mini-Symposium on Tannery Effluents.

30.       Data  obtained  from  questionnaires  sent   to   individual
          tanneries in the industry.

31.       van Vlimmeren, P.J.,  "Tannery  Effluent,"  Journal  of  the
          American  Leather Chemists' Association, Sept. 1972, p. 395-
          396.

32.       van Vlimmeren, P.J., "Tannery Effluent Report to the Members
          of the Effluent Commission of  the  International  Union  of
          Leather   Chemists'  Societies,"  Journal  of  the  American
          Leather Chemists' Association, Oct. 1972, p. 431-465.

33.       Perkowski,  S.,  "Water  Reuse  Systems   in   the   Leather
          Industry,"  Das Leder (Ger.), 21, 63  (1970); Chem.  Abs. 72,
          16326  (1970),

34.       Leather Tannery Waste  Management  Through  Process  Change,
          Reuse   and   Pretreatment,  U.S.  Environmental  Protection
          Agency, Report No. 600/2-77-034, Washington, January 1977.

35.       Williams-Wynn,  D.A.,   "No-Effluent   Tannery   Processes,"
          Journal  of  the  American  Leather  Chemists'  Association,
          Volume LXVIII, No. 1, 1973.

36.       Hauck, Raymond A., "Report on Methods of  Chromium  Recovery
          and  Reuse  from  Spent  Chrome  Tan Liquor," Journal of the
          American Leather Chemists' Association,  Volume  LXVII,  No.
          10, 1972.


                                 339

-------
  37.       Money, c.,  and  Adminis,  u.,   "Recycling  of   Lime-Sulfide
           of L^th9  Llquors-  Im S™311 Scale Trials," Journal  Society



  38.       Frendrup, w., and Larsson, "Effect of Depilating Methods  on
 39.       Theis, Edwin R., o-Flaherty, Fred, -Conservation of Chromium
                        Leather lndustry,« Hide and Leather and  shoes.
 40.       Davis, M.H., Scroggie, J.G.,  "Investigation  of  Commercial

           ^5°m^Tannir,9 Systems Part IV— He-cycling of chrome Liquors
           and  Thexr  use  as  a  Basis  for Pickling," Journal of the
           |22ietv of Leather Technologists and  Chemists, vol. 577 ^


 11.       Davis, M.H., Scroggie, J.G.,  "Investigation  of  Commercial
           Chrome-Tanning  Systems  Part V— Recycling of Chrome Liquors

                                                            <*  ^S

 42.       Burns, J.E., Colquitt, D.E., Davis,   M.H. ,  Scroggie,  J.G.,
            Investigation of Commercial Chrome-Tanning Systems Part VI-
           -Full-scale  Trials  of  chrome   Liquor  Recvclina
           L^taT Sf ^ conce«tration," Journal of ^
           tieather lechnolociists and Chemists, ^/oTTeoTpTTo I

 <»3.       ward,  G.  J.,  slabbert, N.P.,   shuttleworth,   S.G.,   "Recent
           Developments  in   Tannery  Process Modification for Reducina
           stl-560?    S°  d  WaStes'" ^CA.  Vol.  71,  December 1976?^
                     " "Recycle  of  Tan  Liquor  from  organic  Acid
                     Process," JALCA, Vol. 70, May 1975, p.  206-219.

«5.       Pierce, Robert, Thorstensen, Thomas C. ,  "The  Recycling  of
          Chrome  Tanning Liquors," JALCA, Vol 71, April 1976, p. 161-


46.       Robinson,  John  w. ,  "Practical   chrome   Recovery/Recycle
          System," Leather and shoes. August 1976, p. 38-H2.

47.       Telephone contact technical representative Permutit Company
          Inc., Paramus, New Jersey, May 19,  1977.

48.       Chementator,  Chemical Engineering.  May 9, 1977, p. 86-87.
                                 340

-------
49.       Supplement for Pretreatment to the Development Document  for
          the  Leather  Tanning  and  Finishing Point Source Category,
          U,S.  Environmental  Protection  Agency,  Report  No.  440/1-
          76/082, Washington, November 1976.

50.       Koopman, R.C., "Deliming  with  Magnesium  Sulfate:   A  New
          Deliming  Process  in  Which  the Pollution of Wastewater is
          Reduced", Development and Improvement of Tanning Methods, V,
          Deliming and Straining of Skins for Box Leather, Section  D,
          Institute for Leather and Shoes-TNO, June 1974.

51.       Moore, Edward W., "Wastes from the Tanning, Fat  Processing,
          and Laundry Soap Industries,"  Source Unknown.

52.       McKee, Jack Edward, and Wolf, Harold W., eds., Water Quality
          Criteria.  2nd ed.,  The  Resources  Agency  of  California,
          State Water Quality Control Board, Publication No.  3-A 1963.


53.       steffan, A. G., In-Plant Modifications to  Reduce   Pollution
          and  Pretreatment of Meat Packing Waste Waters for  Discharge
          to Municipal Systems, prepared for Environmental  Protection
          Agency  Technology Transfer Program, Kansas City, Mo., March
          7-8, 1973.

54.       Eye, J. David and Clement, David  P.,   "Oxidation of Sulfides
          in Tannery Wastewaters," Journal  of   the  American Leather
          Chemists' Association, Vol. 67, No.  6, 1972.

55.       Bailey, D. A.,  and Humphreys, F.  E., "The Removal of Sulfide
          from   Limeyard  Wastes   by   Aeration,"   British   Leather
          Manufacturer's  Research Association, Laboratory Reports, XV,
          No. 1,  1966.

56.       Chen,  Kenneth Y.,  and  Morris,  J.   Carrell,   "Oxidation  of
          Sulfide  by   02:   .Catalysis  and  Inhibition," Journal  of the
          Sanitary  Engineering Division Proceedings  of  the  American
          Society  of   Civil  Engineers,  Volume 98, No.  SAl, February
          1972.

57.       Kessick,  M.  A.   and  Thomson,   B.  M.   "Reactions Between
          Manganese   Dioxide    and  Aqueous   Sulfide,"  Environmental
          Letters,  Vol. 7,  No.  2,  1974.

58.       Yasuo   Ueno,  "Catalytic   Removal  of  Sodium  Sulfide  from
          Aqueous  Solutions,"   Journal of  the Water Pollution Control
          Federation,  Vol 46, No.  12,  December 1974.
                                  341

-------
 59.       Yasuo, Ueno,  "Catalytic  Removal  of  Sodium  Sulfide  from
           Aqueous  Solutions and Application to Wastewater Treatment "
           Water Research. Vol. 10, 1976.                      duiueut,

 60.       Data obtained by Stanley Consultants field investigations.

 61.       Happich, w.F., et al.,  "Recovery  of  Proteins  From  Lime-
               -
 62,
70.
                                                                   Vol.
           van Meer, A. J. J. , "Technical Note,"  JALCA,  68  (1973),
           346.
 63.        Sutherland,  R.,  Industrial and  Engineering  Chemistry   39
           628,  1947.                                    —	"    '

 64.        Sproul,  Otis J.,  Atkins,  Peter F.,   and  Woodward,   Franklin
           Sliv,  "Investigations  on   Physical   and  Chemical  Treatment
           Methods   for  Cattleskin   Tannery  Wastes,"  Journal   Water
           Pollution Control Federation,  Volume 38,  No.  4,  April 1966.

 65.        "Report  of the Symposium  on  Industrial  Waste  of  the  Tanning
           Industry,"    Journal   of  the  American   Leather  Chemists'
           Association,  Supplement No.^5,  1970.	   	^^  memists
 66.       Howalt, W., and Cavett,  E.   S.,   Transactions   of   American
          Society of Civil  Engineer sf  92, 1351,  1928.                 "

 67.       Riffenburg, H.  B. ,  and  Allison,  W.  w. ,  Industrial   and
          Engineering Chemistry f 33, 801, 1941.                  ~   -

 68.       Hagan, James R.,  and Eye, J.  David,  and   Gunnison,  G    c
                    vea^,hnt0 S**  Rem°Val °f C°lor from Biologica
                    Vegetable   Tannery   Wastes,"   Masters   Thesis
          University of Cincinnati, 1972.            "e^ners   rnesis,

69.       Kinman, Riley  N.,  "Evaluation  of  Bona  Allen  Wastewater

          nn^en£ ^f°r Peri°d Februa*Y 1* 1972 to January 25, 1973."
          Unpublished report, March 5, 1973.

          Parker, Clinton E. , Anaerobic - Aerobic Lagoon Treatment for

          1970?
                     annnq WaStes^ EPA  Grant  12120  DIK,
71.        Biological Treatment, Effluent Reuse,  and  Sludge  Handling
          for  the  Side  Leather Tanning Industry, U.S.  Environmental

              eC                                         ^'
                         i9                 60 0/2-78- 01 3,  Cincinnat
                         1978,  pages 102 and 104.
                                 342

-------
72        Upgrading Meat Packing Facilities to Reduce Pollution  Waste
          Treatment  Systems,  Bell,  Galyardt,  Wells,  prepared  for
          Environmental Protection  Agency  Transfer  Program,  Kansas
          City, Missouri, March 7-8, 1973.  Omaha.

73.       pevelopment Document for Effluent Limitations Guidelines and
          New Source Performance Standards for the Red Meat Processing
          Segment of the Meat Product and Rendering  Processing  Point
          Source  Category,  U.  S.  Environmental  Protection Agency,
          Report No. 440/1-74-012-a, Washington, February 1974.

74.       Lue-Hing, Cecil, et al., "Nitrification of  a  High  Ammonia
          Content  Sludge  Supernatant  by  Use  of  Rotating  Disks,"
          presented at 29th Annual Purdue Industrial Waste Conference,
          May 1974.

75.       Loehr, Raymond C., Agricultural Waste  Management,  Academic
          Press, New York, 1974.

76.       Anthonisen,  A.C.,  Loehr,  R.C.,   et  al.,  "Inhibition  of
          Nitrification  by  Un-ionized Ammonia and Un-ionized Nitrous
          Acid," presented   at   the  47th  Annual  Conference,  Water
          Pollution Control  Federation, October 1974.

77.       Eckenfelder, W., Water Quality   Engineering  for  Practicing
          Engineers, Barnes  and Noble, Inc.,  New  York, 1970.

78.       Adams and Eckenfelder, "Nitrification   Design  Approach   for
          High     Strength   Ammonia   Wastewaters,"   Journal   WPCF,
          Washington,  D.  C,, March 1977.

79.       Nemerow, N.L.,  "Color and Methods  for Color  Removal,"  Proc.
          llth  Ind.   Waste  Conf•,   Purdue   Univ.,  Ext.   Sec.  91 W.
          Lafayette, Ind.,  584  (1956).

80.       Tomlinson, H.D.,  Tackston,  E.L., Koon,  J.H., Krenkel,  P.A.,
          "Removal of Color from  Vegetable  Tanning Solution," Journal
          WPCF, Vol. 47,  No. 3, March 1975,  p. 562-576.

81.       Cheremisinoff,  Paul,  N., P.E.,  "Carbon  Adsorption of Air  and
          Water  Pollutants," Pollution  Engineering July  1976, £_._   2±-
          32.

 82.       Minor,  Paul, S.,  "Organic Chemical Industry's  Waste Waters,"
          Environmental Science S Technology,  Vol.  8,   No.   7,  July
           1974,  p. 620-625.

 83.       DeJohn,  P.B. and Adams,  A.D.,   "Treatment  of   Oil  Refinery
          Wastewater   with  Granular  and  Powdered Activated Carbon,"
           30th Annual  Purdue Industrial Waste Conference, May 6, 1975.


                                  343

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'
85
  86.



  87.


  88.



 89.



 90.

93.
95.
           Conferenc, April i.
           Ferguson,  J.F.,   "Combined   Powdered
           ssas. .
         Barry, L.T., and  Flynn,  B.P.,  "
                                                           Pollution
                                                 Activated   carbon

                                                      Home   for  the
                                                                  °
         Oriw...  c.  a.. st.n.tro.. M.K.. Halk,   J.D..
         Alternative"!"'; "*CtiVated Slud^e  Enhancement:  A  viable
         £e£rt?          Tertiary  Carbon   Adsorption,"  Unpublished

         Black, James P. and Andrews,  James  N.,
                          C
                          Carbons in Wastewater Treatment,"  p  13
        aager,  D.G.,    "Waste   Treatment   Advances:    Wastewater
        Eichelberger, J. w. . and Lichtenberg, J.j.  j
        Works Assn., 63, No.  1, January  1971.      ~
                              344

-------
96.       Masek, V., Gas Woda Tech. Sanit, 39 (8), 1965.

97.       Hager, D.G., and Rizzo, J.L.,  "Removal  of  Toxic  Organics
          from   wastewater  by  Adsorption  with  Granular  Activated
          Carbon," presented at EPA Tech. Trans.   Session on Treatment
          of Toxic Chemicals, Atlanta, April 1974.

98.       Marek, A. C. and Askins, W., "Advanced Wastewater  Treatment
          for  an  Organic Chemicals Manufacturing Complex," U.S./USSR
          Symposium on Physical/Chemical Treatment, Cincinnati,  Ohio,
          November  12-14,  1975.
99.       Shumaker, Thomas P., "Carbon Treatment  of  Complex  Organic
          Wastewaters,"    presented    at    Manufacturing   Chemists
          Association Carbon Adsorption  Workshop,  Washington,  D.C.,
          November  16, 1977.

100.      Mulligan, Thomas J.,  and  Fox,  Robert  D.,  "Treatment  of
          Industrial   Wastewaters,"  Chemical  Engineering/Desk  Book
          Issue, October 18, 1976, p. 62.

101.      Leitz,  Frank  B.,   "Electrodialysis  for   Industrial  Water
          Cleanup," Env. Sci.  and  Tech., Vol. 10, No.  2 February 1976.

102.      Membrane  Processes   for  Treating  Metal  Finishing  Wastes,
          USPA,  Project  12010  HJQ  to the American Electroplaters.

103.      Eckenfelder, W.  Wesley,  Jr.,   "Pretreatment  of  Industrial
          Wastewaters for  Discharge  into Municipal Systems," presented
          at  Technology  Transfer  Seminar,  Minneapolis,  Minnesota,
          October  2,  1976.

104.      EPA Technology Transfer  Document,  "Process  Design Manual  for
          Carbon Adsorption,"  625/1-71-002a, October  1973, p 5-4.

105.      Adams, Carl E.,  and  W.  Wesley   Eckenfelder,   Jr.,  Process
          Design  Techniques   for  Industrial  Waste  Treatment,  Enviro
          Press, Nashville,  TN,  1974.

106.      Assessment  of  Industrial Hazardous .Waste   Practices-Leather
          Tanning   and    Finishing   Industry,   SCS   Engineers,   Inc.,
          prepared for U.S.   Environmental   Protection Agency,   Solid
          Waste Management Program,  Washington,  D.C., February 1976.

 107.      Strier,  M.P.,  Treatability of Organic  Priority  Pollutants  -
          Parts C  and E, Draft Document,  Effluent Guidelines Division,
          EPA,  June 1978,  May 1979.
                                  345

-------
 108.      *nternal EPA Memorandum from M.P. Strier to  D.F.  Anderson

           thfLeath^ Tf°r-the Drel°pment Of ^fluent Limitations for
           the Leather Tanning Industry, May 14 , 1979.

 109.      Plunkett,  Handbook  of  Industrial   Toxicology.   chemical
           Publishing Co.,  1976.

 110.      Siebert, C.L.,  »A Digest  of  Industrial  Waste  Treatment »
           Pennsylvania State Department of Health, 1940.

 111.      Reuning, H.T.,  Sewage  Works  Journal,  20, 525,  1948.

 112.      Harnley, John W. ,  Wagner,  Frank  R. ,  and   Swope,   H.   Gladys,
           "Treatment  of Tannery Wastes at the  Griess Pfleger  Tannery
                               "               Journal, Volume XI??  NO!
 113.      Eldridge,  E.F.,  Michigan  Engineering  Experiment  station
          Bulletin,  87:32, November 1939.                      -

          Fales, A.L., Industrial and Engineering Chemistry, 21:   216
          1929

115.
          "Industrial Waste Survey at Caldwell Lace Leather  Company,"
                     „             • Radiological and Industrial Waste
                     Section, Cincinnati, Ohio.

116.      Eye, J. David, Treatment of Sole Leather  Vegetable  Tannery
          Wastes,  Federal  Water                              	
          Department of Interior,
          12120, September 1970.

117.      Kunzel, Mehner A.,  Gesund,  Ing. 66:300, 1943.

118.      Middlebrooks, E.  Joe,  et al., "Evaluation of Techniques  for
          *£Zll TTRemoval  from  Wastewater  Stabilization Ponds," Utah
          State University, Logan, Utah,  January 1974.

119.      E.C.Jordan Co.,  inc., "Filtration and  Chemically  Assisted
          r^1;1;10^10?  °f  Biol°9ically  Treated Pulp and Paper Mill
          Industry Wastewaters,"  Draft  Report to EPA,  1979.
                                346

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                      SUPPLEMENTAL BIBLIOGRAPHY

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457.
Assessment  of  Industrial Hazardous Waste Practices - Leather Tanning
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Atkinson, John, "A New Application of Mimosa in  Leather  Processing,"
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Bailey  and  Hopkins,  Preservation  of  Hides  with  Sulfite.  II.  A
Matched side Comparison of Leathers from Hides Preserved  with  Sodium
Sulfite or Brine Curing.
Bailey,  Hopkins,  Taylor,  Filachione,  Preservation  of  Hides  with
Sulfite.  ill.  Statistical Evaluation of Shoe Upper Leather  Prepared
in §. Matched Side Study of Brine Cured and Sulfide-Acetic Acid Treated
Cowhides.
Baird,  Carmona,  Jenkins,  "Behavior  of Benzidine and Other Aromatic
Amines in Aerobic Wastewater Treatment," Journal WPCF, July  1977,   Pp.
1609-1615.
Barber,  Nicholas,   "Sodium  Bicarbonate  Can  Settle  Many  Wastewater
Problem Upsets," Pollution Engineering,  Pp.  57-59.

Basic Leather  Technology Tannages Other  Than Chrome.

Benishek, Betty, "Health Hazards,"  The  Leather  Manufacturer,   April
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Berg,  Edward  L., Wastewater Treatment System at Caldwell  Lace Leather
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Bernardin, F.E.,  Jr.,   "Selecting  and  Specifying  Activated-Carbon-
Adsorbtion   Systems,"  Chemical Engineering, October ^18,  1976, Pp.  77-
82.
                                  347

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  Brooks and Rumsey,  Limnol^ oceanoa^  10:521(1965).  P.  12017

                    ^^^^^
                                           ,
wastewater


Clark, Douglas  w. , BOD;  A Re- Evaluation .





Agency,  January 1977.      ^etreatment, U
                                                 Practical  Treatment
                                               .
                                            Environmental  Protection
Effluents."
                                      is- "Effect of
                                    Solids   m   Tannery   Unhairing
                                                 - •«-«-
Cope, Research Findings, U.S.  Fish wildl. Ser.  circ   226
wnoo.
                         th«
                               348

-------
Data obtained through communication with municipal treatment plants.

Data obtained through communication with tannery firms.

Davis   and  Scroggie,  "Investigation  of  Commercial  Chrome-Tanning
Systems - Part III - Recycling of Used  Chrome  Liquors,"  Journal  of
Society of Leather Technicians & Chemists/ Vol. 57, Pp. 53-58.

Downing,   Tomlinson   and   Truesdale,   "Effect   of  Inhibitors  on
Nitrification in the Activated-Sludge Process," J_-_ Proc. Inst.  Sewage
Purif., 3, 537, 1964.
Envirogenics   Systems  Company,  "Development  and  Demonstration  of
Process  for  the  Treatment  of  Chlorinated   Cyclodiene   Pesticide
Manufacturing and Process Wastes," December 1973.
Envirogenics  Systems  Company,  "Status  of Developments of Reductive
Degradation Treatment of Endrin-Heptachlor and Chlordane Manufacturing
Wastes," EPA Contract No. 68-01-0083, September 1974.

Eldridge, E.F., Michigan Engineering Experiment Station Bulletin,   87,
32, November 1939.  Cited in Reference  15.
Eye,  J.  David,  Treatment  of Sole Leather Vegetable Tannery Wastes,
Federal  Water  Pollution  Control   Administration,   Department   of
Interior, Grant No. WPD-185, Program No.  12120, September  1970.

Eye,  J.D.,  "Tannery Waste Management,"  Journal WPCF, Vol.  48, No. 6,
June  1976, Pp.  1280-1281.

Eye and Clement,  "Oxidation of Sulfides in Tannery Waste Waters,"

Eye and Graef,  "Pilot Plant Studies  on  the   Treatment  of   Beamhouse
Wastes  from a Sole  Leather Tannery."
Eye,  J.D.,  "Clarification  of  the • Lime-Bearing   Wastes from a  Sole
Leather Tannery."
Eye,  J. David,  "Tannery Wastes," Journal  WPCF,  June  1971,   Pp.   998-
 1001.
Fales,  A.L.,   Industrial  and   Engineering   Chemistry  21,  216,  1929.
Cited by  Reference  15, Pp.  11770-11772.

Feairheller, Taylor,  Bailey, Windus, "New Amino Acids  Formed  in   Hair
During Unhairing."
Feairheller,   Taylor,  Bailey, Windus,  "Further  Evidence  in  Support of
 the Elimination Reaction as the  Mechanism of  Alkaline  Unhairing."
                                  349

-------
                             0"          1    *<*»<»"**   for   Pesticide
                                                    ,
 Frendrup   w., "The Influence of Unhairing Methods Upon the Amount and

        ?3':«'-'"-
 Giusti  D.M.,  et al.,  "Activated Carbon Adsorption of  Petrochemicals  "
 Journal WPCF,  Vol.  46,  No.  '5,  p.  947,                  retrocnemicals,"



 Vetaut, Goniprow,  "A New Modified  Chrome   Tan   System »   The   T^^

 Manufacturer.  July  1976,  Pp. 20-22.              Astern,    The   Leather



 Grief eneder, "Tannery Effluent."
Hauck, Raymond, -some Notes on Thermal Unhairing."




                                  °" Util""ion of  Fleshings  and  Blue
                                350

-------
Heidemann, E., "A Very Rapid Liming and Tanning Process."

Henderson, Trans. Am. Fish Soc,  88:23 (1959).

Hockenbury and Grady, "Inhibition of Nitrification-Effects of Selected
Organic Compounds," Journal WPCF, May 1977, Pp. 768-777.

Homel and McVaugh, "A Meat Packer's Solution to Meeting 1983  Effluent
Requirements."
Hopkins   and   Bailey,  "Preservation  of  Hides  with  Sulfite.   I.
Concentration and Application Effects on Small-Scale Experiments  with
Cattlehides."
Hopkins,  Bailey,  Weaver,  Korn, "Potential Short-Term Techniques for
the Preservation of Cattle Hides."
Hunter and Sproul, "Cattleskin Tannery Waste Treatment in a Completely
Mixed Activated  Sludge Pilot Plant," Journal WPCF, October  1969,  Pp.
1722-1723.
"Industrial  Waste  Survey  at  Caldwell  Lace  Leather Company," EPA,
Office of Operations, Radiological  and  Industrial  Waste  Evaluation
Section, Cincinanti, Ohio.
Information   from  Polybac  Corporation  on  NITROBAC - Technical Data
Sheet.
Irving, H.M.N.H.,  "The XVth Procter Memorial Lecture: Fact or Fiction?
How Much  Do We Really Know About the  Chemistry   of  Chromium   Today?"
Journal of Society Leather Technologists & Chemists, Vol. 58, P.  51.

Johnston  and Williams-Wynn,  "The  Liritan   Semi-Rapid  Sole  Leather
Tannage," Journal  of Society Leather Technologists   &   Chemists,  Vol.
55, P.  192.
"Tannery  Wastes,"  Journal WPCF, June  1970, Pp.  1188-1189.

Advertisements for Two Oxidation Ditch Systems, Journal WPCF.

Kennedy,  D.C., "Treatment of Effluent  from Manufacturer of Chlorinated
Pesticides  with  a  Synthetic,  Polymeric Adsorbent Amberlite  XAD-4,"
Environmental Science and Technology,  7(2):138 (1973).
Kilik,  Eugene L.,  "A Vision of the  Tannery of  the Future," The  Leather
Manufacturer,  July 1976.
Kinman, Riley N.,  "Treatment of  Tannery  Waste Water  from  Bona   Allen,
Inc.,  Buford, Georgia."
                                  351

-------
                                                                Effluent


         -^^
0"   S"
 Prsses,            "    "N—A^-   ^vent   System   for  Tanning

 Kremen. Seymour S. , "sole  leather Tanning  in a Solvent System."
 Kremen and Southwood,  "The  infiin=»nr>o   ~f  « ^
 Solvent Dehydration of HSes anfsSns...     y<*°9en  ^^  °n
                                               ' "Curing with Used Salt

 Krisnamurthi and Padmini, "Purification of Used salt for Curing."
 Kunzel-Mehner,  A.,  Gesunhd,.. Ing^. 66, 300, 1943
                        "    »«
                .        ,                  »« f-
Effluents.                  '      part of a roini-symposium on  Tannery

                                 352

-------
Maire, Max S., "Engineering Aspects of Solvent Hide Processing."
Maire,  Max  S.,  "Offal  Redux,»  The Leather Manufacturer, September
1976, Pp. 12-23.
"Leather  Chemists  Meet   for   Pollution   Pow-Wowr»   The   Leather
Manufacturer, June 1976, Pp. 9-10.
Marie and Sundgren, "Spray Irrigation of Tannery Wastes."

Marks,  D.R.,  "Chlorinated  Hydrocarbon  Pesticide Removal from Waste
Water," EPA Grant 80315-01, Velsicol Chemical Corporation, May  1975.

Marks, D.R.,  "Testimony of Daniel R. Marks  Respecting   Technology  to
Remove  Endrin   from  Water,"   FWPCA   (307)  Docket  No.   1,  State of
Tennessee, Country of Shelby, March  14,  1974.
Mccreary and  Snoeyink,  "Granular Activated  Carbon  in Water Treatment,"
Journal AWWA, August  1977, Pp.  437-444.
McLaughlin,  Blank, Rockwell, "On the  Reuse  of  Salt in   the  Curing  of
Animal   Skins,"  Journal  American Leather  Chemists Assoc., Vol.  XXIII,
No.  7,  1928.
 "Meet  a   Tough   Contender   -  Dry-Cleanable   Leather,"    Chemical
 Engineering.
 Metzel   and   Somerville,   "Unhairing  Calfskins and Side Leather by an
 Enzymatic Process."
 Minor,   Paul  S.,   "Organic   Chemical   Industry's   Waste   Waters',
 Environmental Science 6. Technology,  Vol. 8, No. 7, July 1974, Pp. 620-
 625.
 Money,   Catherin  A., "Short-Term Preservation of Hides.  II.  The Use
 of Zinc Chloride or Calcium Hypochlorite  as  Alternatives  to  Sodium
 Chlorite."
 "New   Sulfide-Precipitation   Process  for  Removing  Heavy  Metals,"
 Chemical Engineering, May 9, 1977, Pp. 86-87.
 Novak, Cudahy, Denove, Standifer, Wass,  "How  Sludge  Characteristics
 Affect  Incinerator Design," Chemical Engineering, April  1977, Pp. 44-
 48.
 The Chemistry and Technology of Leather,   Reinhold  Publishing  Corp.,
 1956, Edited by O1Flaherty, Roddy, Lollar.
                                   353

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                                            waste
                                                                  Arbor
Pierce and Thorstensen,  -The  Recycling of Cnro.e
                                                  Tanning Liguors .
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  n0f                 n,,°e R— -  s-P—
 Leather Ifechnoloaists S cheS. Vof.  I^'P.  ^f33^  2f  Society  of
                                                      °f





 «Removal of Heavy Metals  fron,  Wastewater," c 4 a. April 26, 1976.


 Reuning,  H.T.,  sewage Works Journal. 20, 525, ma.


 "Revamping  Toxics Control Program at PPa » T
 5,  May  1976.              *-rogram at EPA," Journal WPCF, vol.  48,  No.



 Roberts,  South Med. Jour^,  56:63«, (1963).


 Robinson, John w.  "Pr-^r-»-i ^=1  /-.^

 I Shoes, august 1976! Pp? 38-\2      *eC°V^'R*c^ System,-  Leather
              naae

Vol. 6, P. 8U,  1973.           Aquatic  Invertebrates," Environ.




satyendra. M.,  ,,Some Aspects  of Tannery Effluent Control."



Savage and Zemaitis, -Carrousel Aeration-The Biological Ring."
                                     Hair  .oosening  by  Preliminary
                                354

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Shade,    H.L.,    "Waste  Water  Nitrification,»  Chemical  Engineering
Profession, May 1977, Pp. 45-49.
Shivas, Stephen A.J., "A Study of Tannery Pulped Hair Soils."

Shockor, Joe H.,  "Installation  of  Chappell  Process—Green  Tanning
Corporation," Personal Communication, September 11, 1976.

Shockor,  Joe H., "Split Stream Chemical Treatment of Tanning Industry
Wastewater," presented to New England Tanners Club, February 18, 1977.

Shuttleworth, Dorrington, Cooper, Tutt, Every, "Pilot  Plant  Aeration
of   Tannery   Beamhouse   Liquors,"   Journal   of   Society  Leather
Technologists & Chemists, Vol.  58, Pp. 147-156.
Shuttleworth and Ward, "The Liritan Minimum Effluent Vegetable Tanning
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State  Department of  Health, 1940.
Sivparvathi   and    Nandy,    "Evaluation  of   Preservatives  for   Skin
Preservation."
Steadman,  Thomas R.,  Hillman, M.E.D.,  Pickett, Gordon   E.,   Scantland,
D    Alan,  Jacomet,   Joseph   A.,  and  McClure,  Thomas  A.,  "Potential
Opportunities  for Increasing  the  Utilization  of  Tannery Offal,"  report
prepared by  Battelle Memorial Institute  for the  Tanners1  Council  of
America, February  18, 1977.
Sweeny, K.H.,  and J.R. Fischer, "Investigation of  Means  for  Controlled
Self-Destruction of  Pesticides,"  Aerojet Final Report  on FWQA  Contract
No.   14-12-596,  Water  Pollution  Control   Research  Series 16040 ELO
 06/70, June  1970.
Sweeny, K.H.,   Graefe,   A.F.,   Schendel,  R.L.   and  Cardwell,   R.D.,
 "Development   of    Treatment   Process   for  Chlorinated Hydrocarbon
Pesticide  Manufacturing and Processing Wastes,"   Envirogenics   Systems
 Company, December  1973.
 Sweeny, K.H.  and  Rischer,  J.R.,  "Decomposition of Halogenated Organic
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 Department of the  Interior, June 1973.
 Sykes, R.L., "A Positive Approach to the New  Pressure  Groups  -  The
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                                  355

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                          »P?heUT^; Various Pr°pOSals for Treatment of
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                                                   Salts in
                                                       "  American CouncU
                                                                  for  a
                                                                   Waste
                                          °l  H«   Process  Eguipment, «
                         on
                                     ^^tat     ^  I£2a£^e.  „.,.
 Noventoer  1975.  Pr°teCtiOn  Agency,  Report No.  68-01-3524, Washington,

                                 n
Washington, November  1975?           Agency,    Report   No.   68-01-3524,


                                                         in  the
Chemicals xnaustry,-.
                                 356

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Whitehouse,  "A  Study  of  the  Removal  of  Pesticides  from Water,"
University of Kentucky Water Resources Institute, Research Report  No.
8, December 1967.
Williams-Wynn,  D.A.,  "Adaptation  of  the  Liritan  No-Effluent Sole
Leather Tanning Process  to  the  Production  of  Strap,  Harness  and
Belting Leather," Journal of Society Leather Trades Chemists, Vol. 5b,
p. 188.
Wolverton,  McDonald,  NASA Technical Memorandum, "Water Hyacinths for
Upgrading  Sewage  Lagoons  to  Meet  Advanced  Wastewater   Treatment
Standards," Park 1, October 1975.
Wolverton,  McDonald,  NASA Technical Memorandum, "Water Hyacinths and
Alligator  Weeds  for Final Filtration of Sewage," May  1975.
Wolverton, Barlow, McDonald, NASA Technical  Memorandum,  "Application
of  Vascular  Aquatic  Plants   for  Pollution Removal,  Energy and Food
Production in a  Biological System," May  1975.
Young,  Harlan W.,  "Some  Waste   Treatment   Problems   in  the  Hide  and
Leather Industries," The Leather Manufacturer,  June 1976.
Young,   Harland  H.,   "Effluent Treatment for a Small Tannery,"  JALCA,
 1973.
zogorski  and  Faust,  "Waste Recovery:  Removing   Phenols  Via  Activated
Carbon,"  Chemical  Engineering  Profession, May  1977, P.  65.
                                   357

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                             SECTION XVII

                               GLOSSARY

Aerobic
A  biological  process  in  which  oxygen  is  used  for microorganism
respiration needs.  Especially relating to the degradation process  of
waste matter in the presence of dissolved oxygen.

Anaerobic
A  biological  process in which chemically combined oxygen is used for
microorganism respiration needs.  Relating to  biological  degradation
of waste matter in the absence of dissolved oxygen.

Back
That  portion of the animal hide, especially cattlehide, consisting of
the center portion of the hide along the  backbone  and  covering  the
ribs, shoulders, and butt  (excluding the belly).

Bating
The  manufacturing  step following  liming and  preceding  pickling.  The
purpose  of this operation is to  delime   the  hides,   reduce   swelling,
peptize  fibers, and remove protein  degradation products  from  the hide.

Beamhouse

That   portion  of  the  tannery   where   the  hides  are  washed,  limed,
fleshed, and unhaired when necessary prior to  the tanning  process.
 That portion of the hide on  the  underside  of  the  animal,   usually
 representing the thinnest part of the tannable hide.

 Bend
 That  portion  of  the  hide representing the entire hide cut down the
 backbone with the bellies and shoulders removed.

 Biochemical Oxygen Demand  (BQD5)

 The amount of oxygen  required  by  microorganisms  while  stabilizing
 decomposable  organic  matter  under aerobic conditions.  The level of
 BOD is usually measured as the demand for oxygen over a standard five-
 day period.  Generally expressed in mg/1.
                                  359

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   Slowdown
                                           0
                                           of contaminants in any process
  Blue

  The

  o   -~~~.mi.my.    niaes    in    T
  characteristically blue in  color!

  Buffing
                                              to
                                             96
                                                        Pressing     are
  the nap of the uderide    tn   eaher.    ""   SUrfaCe and
  Buffing Dust


  Small  pieces of leather removed in  the  buff in™
  dust   also  includes  small  particles of a£™    9  °peration-    B««ing
  and 1S of  a  coarse  powder consistency?  abrasive use<3 in the  operation
  Carding
                                                               shearlin,
                                        ****** Which Can ^ oxidized to
                                                   agent  under  acidic
A  measure  of  the  amount of
carbon dioxide
conditions
 Chlorine  Cr>n^act Tank
Chromium  (Total)
Clarification
                                 360

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Coagulant
A  substance  which  forms  a precipitate or floe when added to water.
Suspended solids adhere to the large .surface area of  the  floe,  thus
increasing their weight and expediting sedimentation.

Collagen
The  fibrous  protein material within the hide which provides the bulk
of the volume of the finished leather and its rigidity.

Colloids
Microscopic suspended particles which do  not  settle  in  a  standing
liquid and can only be removed by coagulation or biological action.

Color
A  measure  of  the  light-absorbing capacity  of   a wastewater after
turbidity has been removed.  One unit of color is that produced by  one
mg/1 of  platinum as K^PtCl6.

Coloring

A  process step  in the tannery whereby the  color of  the tanned hide   is
changed  to   that  of  the  desired marketable  product  by  dyeing or
painting.

Combination  Tanned

Leathers tanned with  more  than   one   tanning   agent.    For  example,
 initially   chrome-tanned followed by a  second tannage (called a RETAN)
with vegetable  materials.

Composite  Sample

 A series of small wastewater samples taken over a  given  time   period
 and  combined  as  one  sample  in  order  to provide a representative
 analysis of the  average  wastewater  constituent  levels  during  the
 sampling period.

 Concrete Mixer

 A term often applied to hide processors.

 Conditioning

 Introduces  controlled amounts of moisture to the  dryed leather giving
 it varying degrees of softness.
                                   361

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  Corium
  Curryin
                                              «»  flesh.   Also  called
                                          water system- ciassicaiiy
  Degreasinq
and recovered as   byproduct
Deliming
                                            "
                                                                      to
                                                        from  the
                             s:
 Demineraliza-hion
 Dermis
 That part of the hide which is between the flesh and the epidermis.
 Desalinization

 The  process  of removing dissolved salts from water.
 Detention (Retention)

 The  dwelling time of wastewater  in a treatment unit.
 Dewatering

 The process of removing a large part of the water content of sludges
 DO

Dissolved oxygen.  Measured in mg/1.
                                 362

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Drag-out
Loss of process chemicals and solution onto products during processing
which are  made  up  by  periodic  fresh  addition  of  chemicals  and
solution.

Drum
A large cyclinder, usually made of wood, in which hides are placed for
wet  processing.   The  drum  is  rotated  around  its  axis, which is
oriented horizontally.  Also called wheel.

Dry Milling
The rotating of leather in a large wooden drum with no added chemicals
or water.  Dry milling softens the leather.

Electrodialysi s

A form of advanced  waste  treatment   in  which  the  dissolved   ionic
material  is  removed by means  of a  series  of semipermeable membranes
and electric current.

Embossed
A mechanical process  of  permanently   imprinting   a  great  variety  of
unique   grain    effects   into    the  leather   surface.    Done   under
considerable heat and pressure.

Enzymes
complex protein materials  added  to the hide  in   the  bating  step  in
 order  to remove protein degradation products that would otherwise mar
 hide quality.

 Epidermis

 The top layer of skin; animal hair is an epidermal outgrowth.

 Equalization

 The holding or storing of wastes having differing qualities and  rates
 of discharge for finite periods to facilitate blending and achievement
 of relatively uniform characteristics.

 Equivalent Hides

 A  statistical   term used to relate  the production of tanneries using
 various types of raw materials.  An equivalent  hide is represented  by
 3.7 sq m of surface  area and is the average  size  for a cattlehide.


                                   363

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  Eutrophication
 « excessive growth of aquatic plts


 Fatliquoring
the softness and pUabUiof the


Finishing
                                                 With
                                          "astewater which results
                                      substances
                                            processes-  Regulates

 Fleshing
 tanning, fleshing is often accomplished af^er

 Float    •





 £.•"£* iEL-LTT £-£ °Uhr-  
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Multi-Media Filter
A   filtration   device  designed  to  remove  suspended  solids  from
wastewater by trapping the solids in a porous medium.  The multi-media
fitter if characterized by fill material ranging from large  P«twJ«*
with  low specific gravities to small particles with a higher specific
gravity?  Irldation from large to small media size is in the direction
of normal flow.
Grain
The epidermal side of the tanned hide.  The grain side is  the  smooth
side of the hide where the hair is located prior to removal.
Grease
A  group of substances including fats, waxes,  free fatty  acids,  calcium
and  magnesium   soaps,  mineral  oils,  and   certain  other  non-fatty
materials?  The  grease analysis will measure  both free and   emulsified
oils and  greases.  Generally expressed  in mg/1.
Green  Hides
Hides  which may  be cured  but have  not  been tanned.
 Head
 That part of  the hide which is cut off at the flare into the shoulder;
 i,e.,  the hide formerly covering the head of the animal.
 Hide
 The  skin - of  a  relatively large animal,  at least the size of mature
 cattle.
 Ion Exchange
 The reciprocal transfer  of  ions  between  a  solid  and  a   solution
 surrounding the solid.  A process used to demineralize waters.
 lonization
 The process by which, at the molecular level, atoms or groups  of atoms
 acquire  a charge by the  loss or gain of  one or more electrons.
 Isoelectric Point
 The PH at which  acidic ionization balances basic ionization so that  an
 electrolyte will  not migrate in an electrical field.
                                   365

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  Liming
  Nitrogen

                                                                     n
 Nitrogen^  Nitrat-


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The   reciprocal  logarithm  of  the  hydrogen  ion  concentration  in
wastewater expressed as a standard unit.
Parts per million.  The expression of concentration of constituents in
wastewater, determined by the ratio of the weight of  constituent  per
million  parts   (by  weight) of total .solution.  For dilute solutions,
ppm is essentially equal to mg/1 as a unit of concentration.

Pasting

The  process  step  generally  following   the   retan-color-f atliquor
operations  whereby  the  hide  is  attached  to a smooth plate with a
starch and water paste and dried in a controlled heated vessel.

Pickling

The process that follows bating whereby the  hide  is  immersed   in  a
brine  and  acid   solution  to  bring  the  skin  or  hide  to an acid
condition; prevents precipitation of chromium salts on the  hide.

Plating

The finishing operation where the skin or hide  is  "pressed"  in   order
to make   it  smoother.    Plating   may be done  with an embossing  plate
which  imprints  textured effects  into the  leather  surface.

Polymer

An organic   compound characterized   by   a  large  molecular weight.
Certain   polymers  act as coagulants  or  coagulant  aids.   Added  to the
wastewater,  they enhance  settlement of  small  suspended particles.  The
 large  molecules attract the suspended  matter  to form  a large  floe.

 POTW

 Publicly  owned  treatment  works,   i.e.,  municipal   waste  treatment
 system.

 Pullery

 A  plant  where  sheepskin  is processed by removing the wool and then
 pickling before shipment to a tannery.
 Method of unhairing in which depilatory agents are  used  to  dissolve
 hair entirely in a few hours.
                                  367

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   Retanning
  agents.  fanning  imparts
  Reverse Osmosis
  A  process  whereby  water       r»r-/-    4-~
  membranes under high pressures   S£!       - P3SS thr°Ugh
  relatively  free  of Pd!IsSvId  sollL^^^0^  the »«*rane is
  concentrated form on the f eeFs'idf of^ne ^fane an"
  Sanding
                     tb.
  Sedimentation
  Clarification  (settling)
  Setting_Out
condition for drying
Sharpeners
 Shavin
 Shavins
                                            and stretches
                                      moistur«-   Puts  hides into proper
                                                 <*««"«»••    — «•
the size of wood  shavings?          ^"^ hld6' Which are approximately
Shearling

A lamb or sheepskin tanned with the hair retained.
Shoulder

That part of the hide between the neck and the ,ain body of the hide.
                                 368

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lolT&ll required°if full hides were processed.

Skin
The pelt or skin of animals  smaller than  mature  cattle;  e^,  pigskin.
sheepskin, calfskin.

Skiver
The  thin layer  shaved  or cut off  the  surface  of  finished  leather.
principally  sheepskin.
Sludge

  Staking
  Sulfide
  ionized sulfur.  Expressed in mg/1 as S.

  Suspended Solids  (SS
  constituents suspended in ^stewater «hich can  usually be   remove,  by
  sedimentation  (clarification) or  filtration.
  Syntan
                            •  ••     ~««mva n «  used  in  combination  with
                                                     °             ^
                                    369

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    Tanning


    The  chemicals  derived
                                                                   -
That portion O-F

are perked


Toggling
                                                                   tanning
   The  total amount

   -stevater.
                                                           -organic,   in
                                                                        n
  Trimming
                                  -
 Trimming.c;
                                                           «
 The process where the hair- io
                   «e halr ia removed  from the  hide
A control device  placed   in

measurement or control of  the
                                  370

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PRIORITY  POLLU2MS
 IELD"SAMPLING PROCEDURES
                              APPENDIX A

                                          -  SCREENING AND VERIFICATION
be  estimated.  Raw wastewater samples were o          depending    on
treatment   or   following   min imal   Pr^^^luentPsampies were
                                           r secondary treatment.
The  sampling  method ^-l      and
 The   samp                                           and     t
 being sampled  f o r  sampling at both  the  «£      were used to account
 points.    automatic   samplers   an° ^°" ration.   samples  were  taken
 for  short term ^^^V  coSSS^ was prepared by combining the
 every 15 minutes,  and a  2U hr.  ^P^1^^ f?owS recorded during each
 samples   on the   basis   of  relative  *«"     aliquots  were  removed
 collection period.  From the 24-hr, f""^*1*^ ^Isic  water  quality
 to  satisfy  the   sample  ™qwe*e£s of the^ o       ^^  fQr  the
 paran^ters.  The  remaining volume ^e^|dcom|om   the  water  supply.
 72-hr  composite.    Blanks  were  =?         f    samples  taken  after
 sampling requirements were not ^rigorous ^        £   for activated
 secondary  treatment hbeca«s^heh°^^  SmpiSg Period.   Either  grab
 sludge may be c01^*1^ " the ?ana ; he entire lample  retained, or  an
 SSSirUSJS 'warimployed^^e collected samples were mixed
 for  the  composite.

 normal vinyl tubing, the  Cample  collection  i           ^ samplers
                                        le »~*                  The
  normal vny   u,                                      ^  sa
  backflushed  before and after each sample »^~*   as   sampled.

                                             ssr - —
  The samples and blanks were kept on ice prior to shipment and   shipped
  in insulated containers.
                                    371

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             Method Develop and Procedures

 Minor  changes   in

 verification  processes,  ^Tl^*™*:*^ **
 Volatile organics-   The          SSential  methodology was  the same.





=(«c«o«t« ,« Muis' "" -1"" into th.
                          .,
                                                   a duplicate water
                                                   except  that  the
                               372

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samples  were  acidified  to  PH  1 with HO. prior to extraction.  The
extracts were then analyzed by GC/MS.



electron capture detector.
 procedure



 HN03/K2Cr207,  and HNO3/HC104/H2S01.
 Cyanide:   Samples were analyzed for cyanide by a colorimetric  method.
 Sulfides were removed before distillation.
                                    373

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                              APPENDIX B

                                        netected In

                          Treated Effluents
acenaphthene
acrolein
acrylonitrile
1,2,4-trichlorobenzene
1,2-dichloroethane
hexachloroethane
1,1-dichloroethane
1, 1,2-trichloroethane
chloroethane
bis(chloroethyl)ether
bis (2-chloroethyl) ether
I^chloroethyl  vinyl  ether
 2-chloronaphthalene
 para-chloro-meta-cresol
 2-chlorophenol
 1,3-dichlorobenzene
 1,1-dichloroethylene
 1,2-dichloropropane
 1,3-dichloropropene  (cis- & trans)
 2,4-dimethyIphenol
 2,4-dinitrotoluene
 2,6-dinitrotoluene
 U-chlorophenyl phenyl ether
 4-bromophenyl phenyl ether
 bis- (2-chloroisopropyl) ether
 bis-(2-chloroethoxy) methane
 methyl chloride  (chloromethane)
 methyl bromide  (bromomethane)
 bromoform  (tribromomethane)
 bromodichloromethane
  tr ichlorofluoromethane
  dichlorodifluoromethane
  dibromochloromethane
  hexachlorobutadiene
  hexachlorocyclopentadiene
  2-nitrophenol
  4-nitrophenol
  2,U-dinitrophenol
  4,6-dinitro-o-cresol
  n-nitroso-dimethylamine
  n-nitroso-di-n-propylamine
  butyl benzyl phthalate
  di-n-octyl phthalate

                      (benzo(a)anthracene)


                                    375

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  3,4-benzopyrene (benzo (b) pyrene)
  3, 4-benzof luoranthene (benzo (b) fluoranthene)
      2f   rant^  (b*™ <*> ^orant
  1 , 12-benzoperyiene (benzo (ghi) perylene)
        6ean^acene
indeno 6:^e^anf^acene  (dibenzo (a,k, nthracene)
                  ******
 tricMoro4thlen   ****** M' ^^P^ylene pyren

 a7ldrinChl°ride  (chloroethylene)
 dieldrin
 chlordane
    • -DDE  (p,p«-DDX)
            ^
 a-endosulfan
 b-endosulfan
 endosulfan sulfate
 endrin
 endrin aldehyde
 heptachlor
 heptachlor epoxide
 a-BHC
 b-BHC
 r-BHC  (lindane)
 s-BHC
 PCB-1242  (Arochlor 1242)
 PCB-1254  (Arochlor 1254)
 PCB-1221  (Arochlor 1221)
 PCB-1232  (Arochlor 1232)
 PCB-1248  (Arochlor 1248)
 PCB-1260  (Arochlor 1260)
PCB-1016  (Arochlor 1016)
toxaphene
2.3, 1, 8-tetrachlorodibenzo-p-dioxin  (TCDD)
                                 376

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                              APPENDIX C
                 Toxic pollutants De*^ted In Treated
                   gffluents At Two Plants Or Less
trans-1,2-dichloroethene
1,1,1-trichloroethane
tetrachloromethane
   (carbon tetrachloride)
1,1,2,2-tetrachloroethene
1,1,2,2-tetrachloroethane
chlorobenzene
hexachlorobenzene
n-nitrosodiphenylamine
1,2-diphenylhydrazine
benzidine
3,3•-dichlorobenzidine
nitrobenzene
isophorone
fluorene
fluoranthene
pyrene
 diethyl phthalate
di-n-butyl  phthalate
 chrysene
 2,U-dichlorophenol
                                    377

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                              APPENDIX D

                  Pollutants Detected In Treated Effluents
                  At or Below The Limit Qf Detection
benzene
phenanthrene/anthracene
beryllium
cadmium
mercury
antimony
asbestos*
arsenic
selenium
silver
thallium

      *Total chrysotile  fiber  count
                                    379

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                              APPENDIX  E
2,4,6-trichlorophenol
chloroform
1,2-dichlorobenzene
1,4-dichlorobenzene
ethylbenzene
methylene chloride  (dichloromethane)
naphthalene
pentachlorophenol
phenol
bis  (2-ethylhexyl)  phthalate
toluene
chromium
copper
cyanide
 lead
nickel
 zinc
                                     381



    *U.S. GOVERNMENT PRINTING OFFICE : 1979 0-300-369/6427

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