United States         Off ice of          EPA 130/6-80-002
               Environmental Protection     Environmental Review     August 1980
               Agency           Washington. DC 20460
   «>EPA      Environmental
               Impact Guidelines
                                         NOV?
               For New  Source
               Leather Tanning and
               Finishing  Industries
I
    EJBD
    ARCHIVE
    EPA
    130-
    6-
    80-
    002

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This document Is available to the public through the National
Technical Information Service, Springfield, Virginia  22161.

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  EJBD
   EPA                          US EPA
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                        ENVIRONMENTAL IMPACT GUIDELINES


                               For New Source


                  Leather Tanning and Finishing Industries
                             Repository Material
                            Permanent Collection
                                Prepared by

                               WAPORA,  Inc.
                           6900 Wisconsin Avenue
                           Washington, B.C.  20015
r

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                              ABSTRACT

     This guideline document has been prepared to augment the information
previously released by the Office of Environmental Review entitled
Environmental Impact Assessment Guidelines for Selected New Source Industries.
Its purpose is to provide guidance for the preparation and/or review of
environmental documents (Environmental Information Document or Environmental
Impact Statement) which EPA may require under the authority of the National
Environmental Policy Act (NEPA) as part of the new source NPDES permit
application review process.

     This document has been prepared in seven sections, organized in a manner
to facilitate analysis of the various facets of the environmental review.  The
initial section includes a broad overview of the industry intended to familiar-
ize the audience with the processes, trends, impacts and applicable pollution
regulations commonly encountered in the leather tanning and finishing industry.
Succeeding sections provide a comprehensive identification and analysis of
potential environmental impacts, pollution control technologies available
to meet federal standards, and siting and process alternatives.  The document
concludes with three sections:  a listing of federal regulations (other
than pollution control) which may apply to the new source applicant, a glossary
tjf terms pertaining to the leather tanning and finishing industry, and a
comprehensive listing of references for further reading.

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                                 Preface
     This document is one of a series of industry-specific Environmental
Impact Assessment Guidelines being developed by the Office of Environmental
Review for use in EPA's Environmental Impact Statement preparation program
on New Source NPDES permits.  It is to be used in conjunction with
Environmental Impact Assessment Guidelines for Selected New Source Indus-
tries, an OER publication that includes a description of impacts common to
most industrial new sources.

     The requirement for federal agencies to assess the environmental
impacts of their proposed actions is included in Section 102 of the
National Environmental Policy Act of 1969 (NEPA), as amended.  The
stipulation that EPA's issuance of a New Source NPDES permit as an
action subject to NEPA is in Section 511(c)(l) of the Clean Water Act
of 1977.  EPA's regulations for preparation of Environmental Impact
Statements are in Part 6 of Title 40 of the Code of Federal Regulations;
New Source requirements are in Subpart F of that Part.
                                   ii

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                             TABLE OF CONTENTS

                                                                        Page
TABLE OF CONTENTS	,	     ill

List of Figures	     vii

List of Tables	     viii

INTRODUCTION	     1

1.0  OVERVIEW OF THE INDUSTRY	     3

     1.1  SUBCATEGORIZATION  	      7

          1.1.1  Hair Pulp /Chrome Tan/Retan-Wet Finish	      8
                 (Subcategory 1)

          1.1.2  Hair Save/Chrome Tan/Retan-Wet Finish	      8
                 (Subcategory 2)

          1.1.3  Hair Save /Non-Chrome Tan/Retan-Wet  Finish	      8
                 (Subcategory 3)

          1.1.4  Retan-Wet Finish  (Subcategory 4)  	      8

          1.1.5  No Beamhouse  (Subcategory  5)  	      8

          1.1.6  Through-the-Blue  (Subcategory  6)  	      8

          1.1.7  Shearling  (Subcategory 7)	      8

      1.2  PROCESSES	  .      	      9

           1.2.1  Major  Processes  of  the Leather Tanning and ....      9
                 Finishing  Industry

                  1.2.1.1  Beamhouse  Operations	      9
                  1.2.1.2  Tanhouse Operations 	     13
                  1.2.1.3  Retanning, Coloring,  and Fatliquoring .  .     17
                  1.2.1.4  Finishing  	     18

           1.2.2   Process Variations  for Raw Materials 	     20

                  1.2.2.1  Cattle  Hide Tannery 	     20
                  1.2.2.2  Sheepskin Tannery 	     22
                  1.2.2.3  Pigskin Tannery 	     25
           1.2.3  Auxiliary Support Systems,
                                                                        28
                                      111

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                        TABLE OF CONTENTS (Continued)

                                                                     Page

    1.3  SIGNIFICANT ENVIRONMENTAL ISSUES	    28

         1.3.1  Location	    28

         1.3.2  Raw Materials	    29

         1.3.3  Processes and Pollutants	    29

         1.3.4  Pollution Control	    31

    1.4  INDUSTRY  TRENDS	    32

         1.4.1  Market  and  Demands	     32

         1.4.2  Location	    33

         1.4.3  Raw Materials	    34

         1.4.4   Processes	    36

         1.4.5   Pollution Control	    37

                 1.4.5.1  In-Plant Pollution Control,  	    37
                 1.4.5.2  End-of-Pipe Pollution Control 	    40

     1.5  POLLUTION CONTROL REGULATIONS	    42

          1.5.1   Air Pollution	    42

          1.5.2   Water Pollution	    47

                 1.5.2.1  Best Available Technology (BAT) 	    51

                 1.5.2.2  New Source Performance Standards (NSPS) .    52

                 1.5.2.3  Regulated Pollutants	    53

                 1.5.2.4  Pretreatment Standards for New
                          Sources (PSNS)	    53
                 1.5.2.5  Best Conventional Pollutant Control
                          Technology (BCT)	    54

          1.5.3  Solid Wastes	   55

2.0  IMPACT IDENTIFICATION	   58

     2.1   AIR	   58
                                      iv

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                      TABLE OF CONTENTS (Continued)

                                                                      Page

    2.2  WATER	     58

         2.2.1  Wastewater Generation and Characteristics	     61

         2.2.2  Priority Pollutant Generation in Wastewater Streams     65

    2.3  SOLID WASTE	     68

    2.4  OTHER IMPACTS	     72

         2.4.1  Aesthetics	     72

         2.4.2  Noise	     73

         2.4.3  Energy  Supply	     7^

                2.4.3.1  Energy Consumption and Conservation  ...     75
                2.4.3.2  Cogeneration	     76

         2.4.4  Socioeconomics	     76

          2.4.5  Raw Materials Shipment  and Handling	     79

          2.4.6   Site Preparation and Construction	     80

          2.4.7   Effects on Municipal Treatment Systems 	  .     82

     2.5  MODELING OF IMPACTS .	     83

3.0  POLLUTION CONTROL	     86

     3.1  AIR - STANDARDS OF PERFORMANCE TECHNOLOGY	     86

          3.1.1  Boiler Equipment 	     86

          3.1.2  Buffing Dust Control	      86

          3.1.3  Hydrogen Sulfide Control	,  • •  •      87

          3.1.4  Ammonia	'  '      87

          3.1.5  Odor	      88

     3.2  WATER - STANDARDS OF PERFORMANCE TECHNOLOGY  	      88

          3.2.1  In-Plant Controls	      88

          3.2.2  End-of-Plant Controls	     97

                 3.2.2.1  Preliminary Treatment .' 	     98
                 3.2.2.2  Primary Treatment (Physycal) Operations .    100

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                       TABLE OF CONTENTS (Continued)
                 3.2.2.3  Secondary (Biological) Treatment 	   100
                 3.2.2.4  Advanced Physical Chemical Processess.  .  .   103

          3.2.3  Toxic Pollutants. 	   112

     3.3  SOLID WASTE - STANDARDS OF PERFORMANCE TECHNOLOGY	   113

          3.3.1  Reduction of Hazardous Waste Components 	   114

          3.3.2  Solid Waste Utilization 	   114

          3.3.3  Solid Waste Treatment	   U5

          3.3.4  Solid Waste Disposal	   116

4.0  EVALUATION OF AVAILABLE ALTERNATIVES	   118

     4.1  SITE ALTERNATIVES	   118

     4.2  ALTERNATIVE PROCESSES AND DESIGNS	   121

          4.2,1  Process Alternatives	   122

          4.2.2  Design Alternatives 	   123

     4.3  NO-BUILD ALTERNATIVE	   123

5.0  REGULATIONS OTHER THAN POLLUTION CONTROL	   124

6.0  GLOSSARY	   129

7.0  REFERENCES	, . .  .   146

     7.1  REFERENCE LISTING BY TOPIC	

     7.2  ALPHABETICAL REFERENCE LISTING	

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                               LIST OF FIGURES

                                                                          Page
 Figure

 1.   Geographical distribution of U.S.  tanneries
 2.   General process flowsheet for leather tanning and finishing
     industry	10

 3.   Flow diagram for a typical cattlehide tannery	   21

 4.   Flow diagram for a typical sheepskin tannery	   23

 5.   Flow diagram for a typical pigskin tannery	   26

 6.   Trends in cost and availability of cattlehides for the U.S. market,
     1969-1978	35

 7.   Technology schematic for in-plant control and preliminary treatment
     for the hair pulp/chrome tan/retan-wet finish and hair save/chrome
     tan/retan-wet finish subcategories  	  106

 8.   Technology schematic for in-plant control and preliminary treatment
     for the hair save non-chrome tan/retan-wet finish subcategory .  • •  107

 9.   Technology schematic for in-plant control for the retan-wet  finish
     subcategory	108

10.   Technology schematic for in-plant control for the no beamhouse and
     shearling subcategories 	  109

11.   Technology schematic for in-plant control and preliminary treatment
     for the through-the-blue subcategory  	  110

12.   Technology schematic for end-of-pipe wastewater treatment 	  Ill
                                       vii

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                               LIST OF TABLES
Table                                                                       Page

 1,    In-plant process changes indicated on questionaire from total
       of 46 leather tanneries	     38

 2.    Applicable Federal ambient air quality standards	     43

 3.    PSD increments:  maximum allowable increase by class	     45

 4.    Proposed new source performance standards (NSPS) and' pretreatment
       standards for new sources  (PSNS) for the seven subcategories of
       the leather tanning and finishing industry	     49

 5.    Emissions from the finishing operation of various subcategories
       of the  leather tanning and finishing industry 	     59

 6.    Raw waste loads by subcategory	     66

 7.    Solid waste generation estimates for the leather tanning  industry
       by effluent guidelines subcategory. .	       69

 8.    "Typical" tannery wastewater treatment plant sludge
       characteristics 	     71

 9.    Typical permits, licenses, certifications, and approvals  required
       from Federal, state, regional, and local authorities  for  construc-
       tion and operation of a typical new source tanning facility  .  .  .    126
                                    viii

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                                 INTRODUCTION

     The Clean Water Act requires that USEPA establish standards of perform-
ance for categories of new source industrial wastewater dischargers.  Before
the discharge of any pollutant to the navigable waters of the United States
from a. new source in an industrial category for which performance standards
have been proposed, a new source National Pollutant Discharge Elimination
System (NPDES) permit must be obtained from either USEPA or the state (which-
ever is the administering authority for the state in which the discharge is
proposed).  The Clean Water Act also requires that the issuance of a permit by
USEPA for a new source discharge be subject to the National Environmental
Policy Act (NEPA) .  The procedure established by USEPA regulations (40 CFR 6
Subpart F) for applying NEPA to the issuance of new source NPDES permits may
require preparation of an Environmental Impact Document (EID) by the permit
applicant.  Each EID is submitted to USEPA and reviewed to determine if there
are potentially significant effects on the quality of the human environment
resulting from construction and operation of the new source.  If there are,
USEPA prepares an Environmental Impact Statement (EIS) on the action of issuing
the permit.

     The purpose of these guidelines is to provide industry-specific guidance
to USEPA personnel responsible for determining the scope and content of EID's
and for reviewing  them after submission to USEPA.  It is to serve as supple-
mentary information to USEPA's previously published document, Environmental
Impact Assessment  Guidelines for Selected New Source Industries, which in-
cludes the general format for an EID and those impact assessment considera-
tions common  to all or most industries.  Both that document and these guide-
lines should  be used for development of an EID for a new source leather tannery.

     These guidelines provide the reader with an indication of the nature of
the potential impacts on the environment and the surrounding region from
construction  and operation of leather tanneries.  In this capacity, the volume
is intended to assist USEPA personnel in the identification of these impact
areas that should  be addressed in an EID.  In addition, the guidelines present
(in Chapter I) a description of the industry, its principal processes, environ-
mental problems, and recent trends in location, raw materials, processes,

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pollution control, and the demand for industry output.  This "Overview of the
Industry" is included to familiarize USEPA staff with existing conditions in
the industry.

     One of the principal sources used in preparing these guidelines is the
Development Document for the Leather Tanning Industry prepared by USEPA (1979).
The Development Document represents an evaluation of the industry with its
purpose to identify appropriate control levels for water-borne pollutants as a
basis for establishing effluent limitations.  The Leather Tanning Development
Document was authorized by the Clean Water Act Amendments of 1977 and is
recommended as an additional source of information on the leather tanning
industry.

     This guideline document may be transmitted to an applicant for informa-
tional purposes, but is not intended to represent the procedural requirements
for obtaining an NPDES permit or to represent the applicant's total responsi-
bilities relating to the new source EIS program.  Because the content of an
EID for a specific new source applicant is determined by USEPA in accordance
with Section 6.908(b) of the Code of Federal Regulations, this document does
not supersede any directive received by the applicant from USEPA's official
responsible for implementing that regulation.

     The Guidelines are divided into seven sections.  Section 1.0 is the
"Overview of the Industry," described above.  Section 2.0, "Impact Identifi-
cation," discusses process-related wastes and the impacts that may occur
during construction and operation of the facility.  Section 3.0, "Pollution
Control," describes the technology for controlling environmental impacts.
Section 4.0, "Evaluation of Available Alternatives," discusses the con-
sideration and impact assessment of possible alternatives to the proposed
action.  Section 5.0 describes regulations other than pollution control that
apply to the industry.  Section 6.0 includes a glossary of terms relating to
the leather tanning industry and the general environmental assessment dis-
ciplines.  Section 7.0 presents references available for more in-depth dis-
cussions on the industry, by topic as well as in an alphabetic listing.

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                         1.0  OVERVIEW OF THE INDUSTRY

     Tanning is the process of chemically converting animal skins to leather.
Archaeological evidence indicates that the Egyptians practiced tanning 5,000
years ago and that the Greeks had developed tanning into a well-established
trade by 500 B.C.  Tanners' guilds had been established in Europe by the 12th
Century to regulate and improve the art of leather making (New England Tanners
Club 1965).

     The American tanning industry originated during colonial times and its
colonial beginnings are evident today in the predominance of tanneries in New
England and the Middle Atlantic States.  During the 19th and 20th Centuries,
the source of animal hides shifted westward, leading to the distribution of
some tannery operations west of the Mississippi River  (see Figure 1).  However,
it is estimated that 85% of all tanneries are still located east of the Missis-
sippi.

     The  leather  tanning and finishing industry is  included within the U.S.
Department of Commerce, Bureau of the Census, Standard Industrial Classifi-
cation  (SIC) 3100, Leather  and Leather Products.  The  part of the industry
addressed  in this report is  identified as  SIC 3111, Leather Tanning and
Finishing.

     "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
United  States,  representing about 84% of the  total  estimated weight of hides
tanned  (US Department  of Commerce 1979).   Smaller quantities of  hides and
skins  of  horses,  goats, deer, elk, and other  animals also are tanned  each year
in the  United  States.   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.

     Three major groups of  standard  processing steps are required to  manufacture
leather:   1) beamhouse operations which  wash  and  soak  the hides  or  skins and

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                      Figure  1.  Georgraphical distribution of U. S. tanneries.
     AK:   1
     HI:   0
          States Containing No  Tanneries
SOURCE:   SCS Engineers.  1976.   Assessment of industrial hazardous waste practices
         tanning and finishing  industry.
- leather

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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.

     The complexity associated with the industry is demonstrated by the pro-
cess combinations.   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, highly specialized end-product 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 pur-
chase 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).

     Tannery wastes can create or contribute to the following problems for
Publicly Owned Treatment Works (POTW's) and separate industrial wastewater
treatment facilities:

     •  large pieces of scrap hide and  leather clogging or fouling operating
        equipment;
     •  excessive quantities of hair and other small-scale, screenable solids;
     •  highly acidic or alkaline waste streams;
     •  wastewater flow surges;
     •  excessive loadings of suspended and settleable solids and BOD,., con-
        sistently or in surges;
     •  odors, facilities corrosion, very high dissolved oxygen demand in
        biological treatment system aeration basins, and hazardous gas genera-
        tion from sulfide bearing wastes

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     •  a potential future problem with disposal of sludges containing chrome;
        and
     •  pass through of ammonia nitrogen.

     Each of the problems outlined, except for pass through of ammonia nitrogen,
can be reduced significantly or eliminated by applying pretreatment technology
in leather tanneries.  Fine screening effectively removes hair, fibers, and
scrap material from wastewater and is available in many different configura-
tions, some of which are particularly effective on tannery type wastes.
Screening equipment also must be installed, operated, and maintained properly
to function well.

     Waste streams from specific processes in tanneries can be highly acidic
or alkaline.  If such  streams are  discharged without pH adjustment or mixing
with a different neutralizing stream, the waste stream may create problems
within the sewer or at the  treatment plant.  A pH control mechanism of holding
and mixing various wastes or of directly adjusting the pH of the waste is
easily implemented as  a pretreatment technology.

     Flow and waste  loading surges particularly can disrupt biological treat-
ment systems employed  by  the POTW's, and they can be minimized by equalizing
the rate of flow or waste loading  discharge.  If space limitations at  a tannery
preclude an equalization  tank,  discharge scheduling as practiced by at least
one tannery can reduce the  magnitude of these surges.

     Catch basins, wet wells, and  other preliminary  treatment  facilities that
provide  a retention  time  and space for  solids separation from  the waste stream
can be very effective  if  properly  designed  and  maintained.   Such a facility
requires regular maintenance in order  to operate  consistently  and effectively.

     Municipal  problems in  disposing of municipal  sludge that  contains chromium
can be shifted  largely back to  the tannery.   In such cases,  a smaller quantity
of sludge containing a higher concentration of  chrome is more easily  disposed
in a controlled  environment.  Chrome  recovery and  reuse  technology also  is
available and in use by the industry.   This  substantially reduces the chrome
content  of the  waste stream and of sludges  generated  in  treatment of  these
wastes.

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     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 direct dis-
chargers.  Total industry flow is approximately 52 million gallons daily
(mgd), of which 47 mgd are discharged to POTW's and 5 mgd are discharged
directly to navigable waters (USEPA 1979)  .

1.1  SUBCATEGORIZATION

     The raw material of the leather tanning industry is the hide or skin
subjected to the processing operations.  Manufacturing processes 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 beam-
house operations.  Other significant process considerations include the tanning
process utilized and the presence of finishing operations, including retanning.
Plant size, age, and location  (including  climate), as well as wastewater
characteristics and treatability, represent the secondary factors of the
subcategorization  rationale.

      The  factors considered  for subcategorizing the  leather tanning  industry
include (USEPA 1979):

      •   Raw material  (cattlehide, split,  pickled  sheepskin, shearling,  and
         pigskin).
      •   Manufacturing  processes [beamhouse operations,  tanning  process  (chrome,
         vegetable, alum),  and  finishing operations (including  retanning)].
      •   Plant size.
      •   Plant age.
      •   Plant location and inherent  climate.
      •   Wastewater characteristics  and treatability.

      Raw material  and  manufacturing processes have been determined  to be  the
 most significant factors in subcategorizing the  leather tanning point source
 category (USEPA 1979).  Seven subcategories have  been developed:  four  of the

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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 (USEPA 1979):

1.1.1  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.

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

1.1.3  Hair Save/Non-Chrome Tan/Retan-Wet Fj.nish - 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.

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

1.1.5  No Beamhouse - facilities which process previously unhaired and pickled
cattlehides, sheepskins, or pigskins into finished leather by  tanning with
chrome or other agents, followed by retanning and wet finishing.

1.1.6  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.

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

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1.2  PROCESSES

1.2.1  Major Processes of the Leather Tanning and Finishing Industry

     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 manu-
facturing 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 2.  Each of the four major process
groups  (beamhouse, tan, retan, and wet finish) consists of specific subpro-
cesses.  For the purpose of this study, a manufacturing process is defined as
a single step  in the complete manufacturing operation where alternative steps
may result  in  significantly different waste characteristics.  A process can
consist of  one or  a series  of  subprocesses.   In  any defined process,  sub-
processes  remain the  same.  This concept  of manufacturing  steps seems best to
allow  for  the  variation  of  processes used by  different plants  (USEPA  1979).

     The processes required at a specific tannery  are dependent on  the type  of
hide being tanned  and  the final projected use  for  the leather product.
Individual tanners will  vary process conditions  to meet product specifica-
tions,  which may result  in  considerable  differences between the way a process
is used from one  tannery to another.   The use  of cattle, pig, or  sheep skins
for making leather will  also require slightly  different processing  techniques
 (Section 1.2.2).

      1.2.1.1  Beamhouse  Operations

      The beamhouse operations  prepare  th^ "°w hides  received  from the meat
packer for tanning.

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Beaahouae
                         Receive & Score Bides
                        Figure 2.  General  process flow-
                          sheet for leather tanning and
                          finishing industry.
        lanyard
                               [Bit.]
                              Pickle
                               Ran]
                              I Wring
                               Split
                           I Grain Portion

                              li.
                              I Shav*
Ratan. Color.
Fatliquor
j Ratan |
| Bleach & Coloring]
1
| Fat liquor ing J
,
| Setting Out {
I
[Hanging J Drying [

j Toggling! |_

Pasting

Vacuum
   Finiah
                           |Conditioning j

                                I
(Staking & Dry Milling


I Buffing I

"1
                         Finishing & Plating
                              Measure I
                              | Grade |


                              I Ship |
Source:   U.S. Environmental Protec-
  tion Agency.  1979.   Preliminary
  draft  development  document for
  proposed effluent  limitations
  guidelines and new source perform-
  ance standards for the leather
  tanning and finishing industry.
                                         10

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          Receiving

     Most cattlehides are received at the tannery as salt or brine cured hides
unless the packer is close enough to permit shipping of uncured, green hides
directly to the tannery without danger of spoilage.  Although the curing
process is generally performed at the meat packer and is therefore more closely
associated with the meat packing industry, the commonly used methods have been
outlined below to indicate more clearly the types of pollutants to be expected
at the tannery.

     One process for salt curing involves interlayering hides flesh side up
with granular salt in stacks for 10 to 30 days.  The salt is gradually absorbed
by diffusion and osmosis and replaces the moisture of the hides.  Excess salt
is removed before the hides are rebundled for shipment.

     Currently,  the preferred curing procedure for green hides  is washing and
soaking in brine.  In this process, the hides are agitated  in brine until the
desired salt content is  reached; then they are drained, given a light  coating
of additional  salt,  and  bundled  for  shipment.   The relatively short (2-3 day)
curing  time and  the  associated removal of blood, manure, and other  foreign
matter  during  the  washing make this  process attractive  to both  packer  and
tanner.

           Trimming and  Siding

      The  first process  which usually takes  place at the tannery after  removing
the  hides from storage  is  trimming,  to remove  ragged edges  and  loose pieces of
skin.   Some  cattle hides are cut in half along the backbone (sided) before
further processing.   The smaller skins of sheep  and pig do  not  require siding.
Trimmings are collected  and  sent to by-product manufacturers  or rendering
operations.

           Washing  and Soaking

      Although washing may be  required several  times during  the  tanning pro-
cess, the first washing is primarily intended  to remove the curing salt.  In

                                     11

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addition, soaking of the hide helps restore the moisture in the hide lost
during the curing process.  Other contaminants such as dirt, blood, manure,
and any preservatives which remain on  the hide are also removed during this
process, especially from salt cured or uncured hides.  Hides are usually
washed in vats, drums, or in a  specially designed concrete mixer device called
a hide processor.

          Fleshing

      In  this  operation, hides are  drawn  through a fleshing machine consisting
of a  rubber pressure roller and a  set  of revolving spiral blades which remove
fat,  connective  tissue, muscle, and  flesh which are left on the hide.  Fleshing
is generally  done at the packing house or at  a separate hide processing facility
but sometimes is also  required  at  the  tannery.  When  this operation is performed
before unhairing, it is referred to  as green  fleshing.  It also may be done
after tanning in the case  of  sheepskins, or by caustic burning during the
unhairing process,  in  which case it  is called lime fleshing.  Because recovery
of fleshings  for rendering is common practice throughout the industry, the
waste load  from this operation  is  low.  A  small volume of cold water is used,
however,  to keep the fat  congealed during  the fleshing operation.

          Liming and Unhairing

      Hides  are soaked  in a lime solution and  the  hair is  removed to improve
appearances and  open the fiber  structure to aid  penetration of tanning chemicals.
This  process  also helps remove  unwanted  globular  proteins  from the hide struc-
ture.  Due  to the use  of strong chemicals and the  dissolution of hair and
proteins, this process produces the  greatest  pollution load from the beamhouse.
Unhairing is  performed either as a chemical-mechanical  process called hair-save,
or by an all  chemical  process called hair-pulp or hair-burn.  In both processes,
hides are loaded into  vats, drums, or  hide  processors with a slurry of lime
and sharpening agents  such as sodium sulfide, sodium  sulfhydrate, or more
recently, dimethylamine sulfate, which all  act to improve  the effectiveness  of
this  process.  The  highly  alkaline unhairing  chemicals  loosen and dissolve
hair at  its roots and  cause hide fibers  to  absorb  large amounts  of  moisture
which makes the  hide swell.  This alkaline  swelling may cause a  hide  to  reach
                                      12

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twice its normal thickness.   The concentration of the unhairing slurry and the

length of processing time vary depending on the process.   The two major un-

hairing processes involve:


     •  Hair-Pulp.  If hair is to be chemically dissolved or pulped, stronger
        solutions, higher temperatures, and/or longer processing times are
        used.  Solubilization of the hair protein in this process produces
        high liquid phase pollution loads, particularly with respect to BOD,
        COD, sulfides, and nitrogen.  The sulfide content of this wastewater
        is generally higher than that from the hair-save process due to the
        higher concentration of sharpeners.  Hides and skins are sometimes
        relimed after unhairing to ensure complete hair removal and to ensure
        uniform alkaline swelling of the hides prior to beginning the tanning
        process.

     •  Hair-Save.  For the hair-save process, chemical concentrations,
        temperatures, and processing time are limited to that necessary to
        loosen the hair so that it can be mechanically pulled by a machine
        which is similar  to the fleshing machine with blunt blades.  The
        removed hair may  be washed, baled, and sold as a by-product, but
        markets are limited.  Following mechanical removal of the hair, the
        hide may be reprocessed to  remove  fine hairs and roots by reliming the
        hide and running  it through the unhairing machine a  second  time.


These  unhaired  hides  are  generally  considered  the product from the  beamhouse

and  are  used immediately  at the tanhouse.


      1.2.1.2   Tanhouse  Operations


      The tanhouse operations  convert  the hide or animal  skin (from  the beam-

 house operations or an  outside supplier)  to a durable  material which is not

 subject  to physical or  biological  degradation.


           Bating


      After unhairing, a hide  is swollen from the strong  lime solutions.  The

 bating process is performed  to reduce swelling,  lower pH,  peptize the protein-

 aceous collagen fibers, and  reopen the hide structure to allow removal of the

 protein degradation products.  Hides are loaded into vats,  drums, or hide

 processors with a solution of ammonium salts and enzymes.   Ammonium sulfate or

 ammonium chloride is added to convert the residual lime to a soluble compound

 which can be washed out of the system.  Enzymes such as trypsin are also  added


                                      13

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during the bating process to separate the collagen fibers and condition the
skin.  Ammonia and calcium sulfate  (the result of the lime - ammonium sulfate
reaction) are wastes from this process.  This is one of  the major sources of
nitrogen wastes  from tanning.  The  use of other bating salts, such as magnesium
sulfate or magnesium chloride, is being investigated to  replace these ammonium-
based bating solutions  (Koopman  1974). After bating, hides are thoroughly
washed to remove any substances  that have been loosened  or dissolved.

          Pickling

      When the  hide  is  to be  chrome  tanned,  it must be acidified to prevent
 precipitation  of insoluble  chromium salts on the skin fibers.  The pickling
 operation is not necessary  when vegetable tanning is used.  Pickling also  is
 used to  preserve hides if storage is necessary prior to  tanning.

      Hides are usually pickled for a few hours in the same vat or  container
 used for bating.  Salt is first added  to the vat or hide processor  to  form a
 buffer solution and prevent acid swelling which would damage  the hide.   The
 hide is then pickled in a sulfuric acid  solution  for up  to  12 hours.   Pollutant
 generation from this process is relatively  low, but  there may be significant
 volumes of wastewater unless recycling is  practiced.

           Degreasing

      Skins from sheep, goats, and pigs contain large quantities  of fat and
 grease that must be removed prior to tanning to eliminate problems with dyeing
 and finishing and to allow better penetration of tanning chemicals.   There are
 several alternative methods of degreasing:

      •  Emulsification.  Skins are  washed in a hot water and detergent
         solution to remove grease and oil.  The grease  is usually  separated
         and recovered as a salable  by-product.
      «  Solvent Extraction.  Most pigskins are washed and soaked in hot water
         to raise their temperature  for degreasing.  Following washing, sol-
         vents are added and the skins are agitated to remove grease.  The
         grease and solvent are separated from the wash  water by decanting.
         Grease and solvent recovery are commonly practiced using a solvent
         stripping column.  Recovery processes make solvent degreasing a rela-
         tively low pollution process.  However, there is a small volume of
         wastewater and some solvent is vented directly  to the atmosphere.

                                      14

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        Mechanical.   Some sheepskins may be degreased by mechanically squeez-
        ing the grease, skin oils, and lanolin out of the skin.   The grease
        and oil are recovered.
          Tanning


     Hides or skins are tanned to give them the mechanical properties of

leather, such as abrasion resistance and flexibility, and to prevent them from

decaying.  The two main tanning agents used commercially are chromium sulfate
solutions and solutions of various vegetable tannins.  Alum, other metal

salts, and formaldehyde are tanning agents but are not widely used on a com-
mercial scale.  Certain synthetic tanning agents (syntans) have been developed

over the years, but these are used mostly as auxiliary agents to these prin-

cipal tanning agents.


     These different tanning agents produce leathers with various working

qualities and end uses.  Heavy leathers that require great durability, such as

shoe soles, saddles, or belts, are usually vegetable tanned.  Lighter leathers

requiring greater abrasion resistance  for use as garments or shoe uppers are

usually  chrome  tanned.  Leather may be  tanned by one operation or it may be

tanned and retanned  in two different  solutions  to  impart  different qualities

to the  leather.   The major alternatives involve:


      •   Vegetable Tanning.  Vegetable  tanning,  the older  of  the  commercially
         used  tanning processes, takes  several weeks.   The hides  are  gently
         agitated in  rocker vats containing  a solution  of  vegetable extracts
         or they are  soaked in  vats containing progressively  stronger solutions
         of tanning  liquor.  Vegetable  tanning solutions are  made of  quebracho,
         wattle, chesnut,  eucalyptus,  and  other  vegetable  extracts.  With the
         cost  of tanning  chemicals and  labor escalating, vegetable tanners are
         recycling tanning solutions by refortification and using higher con-
         centrations  of tannins  to reduce  processing time.   Synthetic tanning
         agents  also  may  be used to improve  dispersion  and penetration of the
         vegetable tanning solutions into  the hide  fiber.  Following  tanning,
         the  leather  is covered, allowed to  stand  for about 42 hours, and
         washed  of excess tannins.

      •  Chrome  Tanning.   Most leathers today are  chrome  tanned.   While  they
         are  light use  leathers, they  have more  resistance to heat and abrasion
         than vegetable tanned leathers.  Chrome tanning  requires less than one
         day.   Chromium atoms  are  believed to react with  the  hide proteins by
         bridging the space between carboxyl and amino  groups on  adjacent
         protein molecules.  Tanning is generally  carried  out in  a vat or hide


                                    15

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        processor using proprietary mixtures  of  basic  chromium sulfate.   This
        produces a hide at  the blue tanned  stage,  so named due to  its  color.
        Chrome  tannery wastes do  not  contribute  high concentrations  of con-
        ventional wastes  such as  BOD,  but do  contain high concentrations  of
        dissolved solids  and potentially toxic  trivalent  chrome.   Tanning
        solutions are sometimes made  by  reducing hexavalent sodium dichroraate
        with sulfuric acid  and sucrose to produce the  trivalent chrome neces-
        sary for tanning.   Accidental spills  are therefore the only  source of
        the  more dangerous  hexavalent form  of chrome which might be  found in a
        tannery.
           Wringing

      Wringing  removes  excess moisture from the hide before it  is  split.  This
 is done by feeding the hides through a machine with two large  rollers similar
 to a  clothes wringer.   For plants in the through-the-blue category  (Subcategory  6)
 this  completes the processing of  the hides and the wet blue stock generally is
 sold  to another plant  for  the retanning and wet finishing operations.  For
 other tanneries,  the tanned hide  is  processed further to produce  the required
 leather product.

           Splitting

      Because hides are  usually too thick for most uses,  the finer grade grain
 leather is  often  separated  from the  flesh side leather (called the split)
 after the  initial  tanning operation  using a machine resembling a  horizontal
 bandsaw.   Splitting following  the unhairing process (referred  to  as lime
 splitting)  was  once a common practice,  but this is not practiced  extensively
 today.  Splits  are either processed  separately at the tannery or  sent to
 another tanner  who processes splits.   In the case of pigskin,  the split is
 sold  to fertilizer manufacturers as  a by-product  since pig splits are of no
use as leather.  The grain  portion of  a hide may  be shaved to  remove any
fleshy matter from the hide  that was not  removed  with the splitting knife.
The shaving machine is also  used to  level  the hide to a  uniform thickness.
                                   16

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     1.2.1.3  Retannlng, Coloring, and Fatliquoring

     Following the initial tanning process, which is primarily for preser-
vation of the fibers, operations are carried out to impart the desired look,
feel, and working qualities specified by the customer.  Hides at the blue
stage are placed in drums and first treated with retan formulations, followed
by dye formulations, and then by fatliquoring chemicals.

          Retanning

     Retanning is a second tanning step commonly used to alter the character-
istics of the leather.  This may involve vegetable retanning of a chrome
tanned leather to give it some of the plumpness and workability of a vegetable
tanned leather, or chrome or synthetic tanning of a vegetable tanned leather
to give it some of the durable qualities of chrome tanned  leather.  It is  in
the retanning process that most synthetic  tanning agents  (syntans) are used.

          Bleaching

     Vegetable  tanning  of  some  leathers  such  as  those used for  shoe soles  may
be followed by  bleaching to  improve  the  color characteristics of  the tanned
leather.  This  is usually done  immediately following  the tanning  process.

          Coloring

      Following  the retanning step,  leather may be  adjusted to  the desired
color using natural or  synthetic  dyes.   This  is usually done in the  same  vat
as  retanning.   These dye wastes are a concern due  to  the complex organic
composition of  some of  the dye  materials (e.g.,  analine derivatives  and organo-
metallic substances).

          Fatliquoring

      The final  wet process for  leather is to add oils and greases to the
 tanned hides to replace those lost during processing.  This prevents  cracking
                                       17

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and makes the leather soft, pliable, strong, and  tear-resistant.  Fatliquoring
is usually carried out by immersing the hide in an emulsion of oil and fatty
substances at a temperature of 120° -  140°F for a few hours.  Aliphatic mineral
oils are sometimes used in small quantities for heavy industrial and shoe
leathers.

     1.2.1.4  Finishing

     Finishing requires a series of dry operations which give leather its
final attractive surface qualities.  Little if any finishing is done to vege-
table tanned hides; however, chrome tanned hides  may be  put through any of
several finishing processes.

          Setting Out

     Setting out smooths and stretches the skin,  while compressing and squeez-
ing out excess moisture.
          Drying
     Drying is accomplished by four different methods:

     •  Hanging.  The hide is draped over a horizontal  shaft which is
        usually passed through a large drying oven.
     •  Toggling.  The skins are dryed in a stretched position on frames.
        The frames are slid into channels in a drying oven.
     •  Pasting.  The skins are pasted onto plates which are then transported
        into a drying oven.
     •  Vacuum.  The hides are smoothed out on a heated steel plate and
        covered by a perforated belt or cloth-covered steel plate.  A
        vacuum is pulled which extracts water from the  leather.  Unlike the
        first three processes riiich take four to seven hours per skin, this
        method requires only three to nine minutes.  However, this method
        has limited application due to shrinkage.
                                     18

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          Conditioning

     Hides are sprayed with a water mist and then piled on a table, wrapped in
a watertight cover, and kept overnight to permit uniform moisture distribution
in the leather.  This improves the handling characteristics of the hides
during subsequent operations.

          Staking and Dry Milling

     Staking is done on automatic machines which stretch and flex the leather
to make it soft and pliable.  Dry milling consists of tumbling the hides in a
large drum.

          Buffing

     Buffing is a  light sanding operation performed on  the grain or split side
of leather to  smooth or correct irregularities  in the grain surface.  Dust
from this operation is the  industry's most  significant  air pollutant.

          Finishing

     A number  of finishes may  be  applied to leather by  rolling or  spray  ap-
plication depending on the  end use  of the  leather and  type of hide.  Various
coating materials, both water-based and solvent-based,  are used  to provide
abrasion  and stain resistance  and to enhance color.   Solvent-based coatings
are  sometimes  used for high luster finishes,  but  their  use is being reduced
due  to handling  problems and fire hazards.

           Plating

      The  final processing  step which influences the appearance and feel  of
 leather is  plating, which  is performed  by  pressing the  leather onto a  large
 smooth surface.  This smoothes the surface of coating materials  applied  to the
 leather while  bonding them firmly to the grain.  The  finishing and plating
 operations  are carried out  in conjuction with each other over a  period  of  four
 to five days.  Hides  may also be  embossed  (stamped with a particular pattern)
 in conjunction with this process.

                                      19

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          Measuring

     The hide area is determined electronically and the area is stamped on the
back side of the hide.

          Grading

     Grading determines  the quality  of  the  finished product.  Leather is
graded by experts  for temper  (the  feel  and  relative solidity), uniformity of
color and thickness, and the  extent  of  any  surface defects.

1.2.2  Process  Variations for Raw  Materials

     Significant variations  in the basic preparatory  and  tanning processes
described here  are required  for the  three major  types of  hides or skins used
by the  tanning  industry.  The major  process techniques for  these hides are
discussed below.

      1.2.2.1  Cattle Hide Tannery

     Cattle hides, which make up the vast majority of tannage  in  the United
 States,  are typically processed as indicated in Figure 3.

          Beamhouse

     The hides are first trimmed of  ragged perimeter areas and then split down
the backbone (i.e., sided) in order  to make manageable-sized hides  for  pro-
cessing. As outlined in the general process description, these hides  are
washed,  soaked, fleshed, and unhaired using either the hair save or hair  pulp
process.  If hair is saved,  it may be washed, bundled, and sold as  a  by-product,
but the  hair pulp  process is currently favored by tanners due  to its  lower
handling and labor costs.
                                       20

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        Figure 3.   Flow  diagram for a  typical cattlehide tannery.
         FUOW DIAGRAM
         TYPICAL CATTLEHIDE TANNERY
• IMS ut lunn
mccu wnnui
                                            CTM-GKOt-nniQUB
                                                              FINIVIM
                                1 I*1"1   .
                                 |mn tun (IUIMI
                                «uit imwrt ,  _
                                 I Ixua	-«
                                 j mil urn (UHUMI   _
SOURCES  U.S. Environmental Protection Agency.   1974.  Development document
         for effluent limitations  guidelines  and new source  performance
         standards  for the leather tanning and  finishing point source category.
         p.  13.
                                        21

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          Tanhouse

     Most cattle hides are tanned either by chrome or vegetable tanning pro-
cesses as outlined in the general process description.  The basic tanning
process used for cattle hides is almost identical regardless of the end use of
the leather.  Hides are delimed, bated, and pickled for a few hours in an acid
bath prior to tanning, although the pickling is not necessary for vegetable
tanned hides.  The final desired characteristics of the leather are obtained
through retanning and subsequent steps.

          Retan. Color, Fatliquor

     As outlined in the general process description, retanning may be per-
formed in a drum using a variety of tanning agents (i.e., chrome, vegetable,
alum, syntans, zirconium, and other metal-based tanning agents).  Hides may be
colored and fatliquored for  short periods in the same drum using analine-based
dyestuffs and animal, vegetable, or mineral-based oils.

          Finishing

     The finishing of cattlehide leather  is dependent on final product re-
quirements, and may involve  any of the processes in Section 1.2.1.4.

     1.2.2.2  Sheepskin Tannery

     Sheepskins are typically processed as  shown in Figure 4.  Most sheepskins
are received at the tannery  with the  wool already removed, so there is essen-
tially no beamhouse operation needed.  Shearling skins, which are received
with the wool still attached, are tanned  to keep the wool intact and require
no beamhouse operation except for fleshing.  Most sheepskins are imported so
they are typically received  already pickled with brine and acid.  Shearlings,
however, are preserved in brine only.
                                    22

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       Figure 4.   Flow diagram  for a  typical  sheepskin tannery.
         FLOW DIAGRAM
         TYPICAL SHEEPSKIN  TANNERY
                                                 COLOft-FATLIQUOR
      (>) SHEARLIII&S (WOOL LEFT M) ARE
        RECEIVED AS CURED SKINS. TAH-
        HOUSE SUB-PiOCESSES INCLUDE
        •ASH t SOAK, FLESHIW. DEfiHEAS-
        !*&. PICKLING AND TAMKITG.
ums
DECREASING
                                  [_>l*STE EFFLUEfT
SOURCE:  U.S. Environmental Protection Agency.  1974.  Development document
          for effluent limitations guidelines  and new source performance
          standards for  the leather tanning  and finishing point source category.
          p.  21.
                                       23

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          Tanhouse

     No special provisions for sheepskin storage are made at most tanneries.
The skins are kept moist and biocides  (e.g.,  chlorinated phenolics) are used
to retard bacterial action and increase storage time.  Pickled skins held for
extended periods should be kept below  30°C  (86°F)  to avoid deterioration.

     Skins from storage are inspected  and fleshed.  Skins which have been
fleshed prior to receipt at the tannery will  usually be refleshed after tan-
ning.  Shearling hides are usually fleshed  after a wash and soak operation.
The fleshing machine  is similar to that used  for cattlehides, with the skin
carried through rollers and across rotating spiral blades.  Skins are placed
in drums, washed,  and soaked,  after which they are degreased as discussed in
Section 1.2.1.2.   Grease  is recovered  as a  by-product from those skins which
have had the wool  removed.  When  solvent degreasing is used, the solvent is
recovered and reused. Because shearlings require  substantial water in the
soaking and washing  (scouring) operations,  grease  recovery is not normally
practiced.

     Sheepskins may be either  chrome or vegetable  tanned, although the major-
ity are chrome tanned.  Where  the skins have  been  received at the tannery in
the pickled condition, there are  no liming  or bating operations.  Skins from
the degreasing operation 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.  Shearling skins also  require pickling to prepare them
for the chromium tanning process.

     In some cases, there is a refleshing operation following tanning, which
produces a small amount of solid  waste containing  chrome.

          Retan, Color, Fatliquor

     Retanning is  performed in a  manner similar to the  cattlehide retanning
operation.  Skins  to  be colored are immersed  in a  dye  solution  in drums.
Synthetic dyes are generally used, and some bleaching may  be  done prior  to
coloring of shearlings.  Fatliquoring  is performed in  the  same  drum used  for
                                     24

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coloring.  Skins are immersed in a solution containing various oils to replace
the natural oils of the skin lost in the tanning process.

          Finishing

     There are a number of operations which follow the coloring and fat-
liquoring process, including drying, skiving (shaving), staking, carding,
clipping, sanding, and buffing.  These are essentially dry processes, and the
only liquid waste contributed is from cleanup operations.  Solid wastes from
the finishing operation include trimmings and skivings.

     1.2.2.3  Pigskin Tannery

     The pigskin tanning processes are similar to those for sheepskins in that
there is essentially no beamhouse process, since most skins have the external
hair removed at the packinghouse.  Degreasing of the skins is a required
tanhouse process.  A schematic of a  typical pigskin tanning operation is shown
in Figure  5.

           Tanhouse Process

     Nearly  all pigskins  are received  at the  tannery  either as  fresh frozen
skins or as  brined refrigerated  skins.   They  are usually  tied in bundles that
weigh 40 to  50 pounds.   In  some  cases,  frozen skins are received in paper bags
rather  than  bundles.   Refrigerated  storage is used at  most tanneries when
skins are  to be held before tanning.  The required degreasing is usually done
by  the  solvent method  described  in  Section 1.2.1.2.   In this  process,  the
skins are  placed  in drums,  then  washed  and soaked  in  warm water to bring them
to  a temperature  suitable for degreasing.  Solvent is  then added and the skins
are tumbled  to remove  the grease.   The  solution of solvent, grease, and water
is  pumped  from the drums  to large tanks where some separation is achieved by
decanting.  From  the  tanks  the solvent  and grease  are sent to a stripping
column  where the  solvent  is recovered  for reuse and the grease  is  recovered as
a by-product.
                                       25

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        Figure 5.  Flow  diagram for a typical pigskin  tannery.
         FLOW DIAGRAM
         TYPICAL PIGSKIN TANNERY
                                             COlM-FtTllOUOl
SOURCE:  U.S. Environmental Protection Agency.   1974.  Development
         document  for effluent limitations  guidelines and new source
         performance standards for the leather  tanning and finishing
         point  source catagory. p. 24.
                                •26

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     An alternate method, In which the skins are tumbled in hot water and
detergent, has also been used.  With this operation, grease is recovered by
decanting or skimming from the top of holding tanks to which the waste has
been diverted prior to entry into the main plant sewer system.

     From the degreasing operation the skins are placed in tanning drums with
a lime slurry and sharpeners, which remove the embedded portion of the hair
from the skins.  This is followed by bating and pickling in the same drum.
While pigskin may be either chrome tanned or vegetable tanned, the only major
tanner of pigskin in this country is using the chrome tanning process.  Chrome
tanning is conducted in the same drum used for pickling.  Current practice is
to fully tan the skins in this operation, eliminating any need for a retan
operation at a later point.

     After tanning, the  skins are tumble  dried and  then split and shaved to
obtain the desired thickness.  The split  portion of the pigskin has no com-
mercial value  as  leather, and it  is  baled with other  scraps and sold as a
fertilizer component.  The  grain  sides  go to  the color and fatliquor process.

          Color,  Fatliquor

      Skins  to  be  colored are immersed in a  dye  solution in drums, generally
consisting  of  synthetic  dyes.   Fatliquoring is  performed  in  the same drum used
for coloring.   The skins are immersed in a  solution containing various  oils  to
replace  the natural  oils of the skin lost in the tanning  process.

           Finishing

      The operations  that follow the coloring and fatliquor process  include
 drying,  coating,  staking, and sanding.   These are principally dry processes,
 and the only liquid  waste contributed is from cleanup operations.   Solid
 wastes from the finishing operations include trimmings,  which are baled with
 the split and shave wastes and sold as fertilizer.
                                     27

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1.2.3  Auxiliary Support Systems

     Relatively few auxiliary support systems are required by the leather
tanning and finishing industry.  Boilers are operated for internal heating
systems and steam generation but these are not major demands.  Other in-plant
systems, such as solvent recovery  systems for the degreasing process and
evaporators for concentrating spent  tanning  liquor, actually serve as waste
treatment and resource  recovery systems.

     When hide curing is done at a separate  facility rather than at the meat
packing plant, it may be considered a  support system for the leather tanning
and  finishing industry.  In these  cases,  certain other  operations normally
associated with the  tannery, such  as fleshing and washing, may also be per-
formed.  These curing and  washing  operations can be a significant source of
pollution  in the  form of dissolved solids, blood, manure, and dirt, and should
be clearly identified if they are  to be  included at  the tannery.

1.3   SIGNIFICANT  ENVIRONMENTAL  ISSUES

1.3.1  Location

      Tanneries traditionally have  been relatively small operations which do
not  involve  large numbers  of employees,  large volumes  of water, or bulk raw
material shipment, and  therefore have  not been of great significance on a
national or regional level.  However,  as  the trend  for  new facilities  favors
uniform production techniques and  mass production,  the  emphasis on  large
facilities can be anticipated.  Such facilities may result  in  the  following
local  impacts:

      • A  tannery may involve changes  in  land use and  result  in  direct and
        indirect  social and ecological impacts.
     • Significant  liquid and  solid phase waste loads  from a  tannery  may
        overwhelm the publicly  owned treatment  works  (POTW)  and  land  disposal
        facilities of a small community  if  these existing  systems  are to be
        used by the  industry.
     • A new tannery may  be a  member  of  an  industrial  complex involving  the
        processing of meat and  meat by-products  which could  collectively have
        a greater impact on the community than  the  tannery  itself.
                                      28

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     •  Secondary impacts during construction of a new tannery may  be  signif-
        icant in smaller communities.
     •  Long-term trends for larger facilities (Section 1.4.1) and  the exis-
        tence of tannery towns indicate that income in these areas  could be
        increased sufficiently to induce spin-off development.

1.3.2  Raw Materials

     No raw materials are used in sufficient quantity to constitute a major
environmental problem.  Resources required at a tannery include hides; water;
process chemicals such as lime, chromium, sulfides, ammonium salts, and sul-
furic acid; and energy.  These requirements usually will not pose a significant
environmental issue if Best Management Practices are required as described by
the Clean Water Act (Section 304e).  Special areas of concern include:

     •  Dissolved solids loading in the  tannery's  liquid waste stream due to
        salt or brine cured hides.
     •  Trivalent chrome tanning solution production by reducing the highly
        toxic hexavalent sodium dichromate  with acid and a  carbon  source.
1.3.3  Processes and Pollutants

     Wastewater  characteristics vary among  tanneries based  on such factors  as
type and condition  of raw hide, final  product,  processes and process  equipment
used  (e.g.,  hide processors),  and  tanning agent.   The  pollutants basically
differ little from  those in wastewaters  of  many other  industries and  can be
treated by conventional methods for  suspended solids  reduction, oil and grease
removal, pH  control, and BOD  reduction.   Specific constituents peculiar to
certain tanning  processes, such as chromium and sulfide, can be removed with
available  treatment methods currently  practiced by the industry.

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

                                       29

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     The strong chemical solutions required by many of  the processes and the
high strength organic wastes can interact to create a wastewater  including

toxic substances that may inhibit biological treatment  processes.  Waste
treatment is difficult because  of hydraulic surges  from batch  process  dumps of
waste material.  Furthermore, the variability  of  processes within the  industry

can result  in treatment  problems applicable only  to a  few tanners, making

these difficult  to predict  and  possibly requiring unique solutions.


     The sources and characteristics of process-oriented problems which have

potentially significant  environmental effects  are highlighted  below.

     •   Large  quantities of wastewater may be  generated containing high con-
         centrations of salt and organics in the form of blood, manure, and
         dirt from the hide washing operation.

     •   A large volume of high pH wastewater with high alkalinity, sulfide,
         nitrogen,  and dissolved and suspended proteinaceous  matter concentra-
         tions  is generated by the unhairing process.

      •   A low pH wastewater with high trivalent chromium concentration is
         generated by the chrome tanning process.

      •   Toxic  hydrogen sulfide gas can be produced if  the pH of the unhairing
         waste  is allowed to fall below 9.0 as a result of mixing with  some
         other process or waste stream.  This is a potentially serious  problem
         both from the standpoint of worker safety and  effects on the sur-
         rounding environment.

      •  Process solutions from the dyeing and finishing operations contain
         a variety of priority pollutants other than chromium.  These include
         organic dyes, solvents, heavy metals, chlorinated hydrocarbons,  bio-
         cides, condensation products of formaldehyde,  and others.  The National
         Institute of Occupational Safety and Health has reported a striking
         increase in the incidence of bladder cancer among leather workers
         which may be related to dyes (USEPA 1978b).

      •   Large quantities of noxious and in some cases, hazardous, solid wastes
         may be generated from screenings, trimmings, and shavings.

      •   Noxious odors may be caused by the sulfides in the unhairing  and
         bating processes, and from the decay of flesh,  or other  putrescible
         matter that is not quickly and properly disposed.
                                       30

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1.3.4  Pollution Control

     Measures taken to control process pollution from the leather tanning
industry constitute an entire set of processes and related environmental
problems within themselves.  Because of the nature of tannery wastes, it is
often most effective to eliminate the pollutants at their source by process
substitution or recovery, especially for the toxic or priority pollutants.  In
other cases, it is most effective to concentrate wastes by recycle or reuse,
so that process solutions may be more efficiently used and waste products may
be mor6 easily treated and disposed.  Still other processes are employed to
physically, chemically, or biologically change the wastes to less hazardous or
objectionable forms.  Finally, treated residuals must be properly handled and
disposed, especially in the instance of hazardous solid wastes.  The sources
and characteristics of waste treatment related problems which may potentially
have significant environmental effects are highlighted below:

     •  Combined treatment of beamhouse and tanhouse streams require that
        pH levels be maintained high before biological treatment so that
        hydrogen sulfide will not be generated.
     •  Sludges from screening, coagulation/sedimentation, biological treat-
        ment, and dewatering units may contain chromium and other priority
        pollutants removed from process waste streams all over the plant.
        Care must be taken in disposing these hazardous wastes in accordance
        with applicable regulations.  For example, chromium may be leached out
        of sludge by acetic acid produced by the decay of garbage in landfills
        (SCS Engineers 1976).
     •  Odors may be generated by sludge handling processes, if the sludge
        has not been properly stabilized prior to dewatering and disposal.
     •  Interstream transfer of wastes occurs in many waste treatment pro-
        cesses and this must be considered in the assessment of pollution con-
        trol effects.  Buffing dust which may contain chromium can be removed
        from the air waste stream, enter the liquid waste stream by wet  scrub-
        bing, and eventually appear in the solid waste stream after wastewater
        settling.  Conventional and priority pollutants are removed  from the
        liquid waste stream and enter the solid waste stream in the  screening,
        sedimentation, and biological treatment steps.  Waste may also enter
        the air stream from the liquid waste stream, as in the case  of hydro-
        gen sulfide generation.
                                     31

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1.4  INDUSTRY TRENDS

1.4.1  Markets and Demands^

     Products of the tanning and  finishing  industry  are used  to make  familiar
consumer goods such as shoes,  belts, handbags,  and garments as well as  saddles,
gaskets, and athletic equipment.   The  main  raw  material of  the industry is
cattlehides  (84% of the  industry's production)  with  much smaller  numbers  of
sheepskins,  pigskins, horsehides, and  wild  animal skins being used.   (U.S.
Department of Commerce 1979).   Since hides  are  a by-product of the livestock/
meatpacking  industry,  their supply is  dictated  by the demand  for  meat rather
than the demand  for leather.   Worldwide demand  for cattlehides exceeds  the
supply which has caused  a recent escalation in  the cost of  raw hides  and
finished  leather products.

      Tanners also process significant  numbers of tanned sheepskins, calfskins,
 lambskins, and  pigskins, as well as other types of skins including kip  (immature
 cattle),  cabrettas, and  horsehides.  Production of these leather  types  has
 declined  since  1960,  although a trend  toward removal of pigskins  prior  to
 butchering may  lead to more pigskins and increased production of  pigskin
 leather.

      Beginning  in the mid-1960's 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 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.

      More recent data for 1975 and projections  for  1976 production show total
 industry  production,  both in equivalent number  of hides and in total dollar
value, to be increasing.  Cattlehide exports generally increased  from  1965  to
 1975.  During  the same period, a general increase in finished leather  import
dollar value was experienced; however, the dollar value of finished  leather
exports also increased.   Finally, in 1975,  leather exports exceeded  leather
 imports as measured in dollars.

                                       32

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     Increase in leather production, increase in dollar value of total industry
production of leather, and increase in dollar value of leather for export are
three indications of a viable U.S. leather tanning and finishing industry.
Management and owners of tanning operations express confidence in the industry
both verbally and by continuing capital investments in tanneries.

     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.

1.4.2  Location

     The geographical  distribution of U.S.  tanneries  is  shown in  Figure  1.
The principal areas  for tanneries  are  in New England,  the Middle  Atlantic
States, the  Chicago-Milwaukee  area, and the Pacific Coast (USEPA 1979).   The
distribution of  tanneries  has  not shifted in recent times as indicated by the
average age  of  tanneries  shown below:

                Age  of plant                       Percent of plants
                Less than  10 years                         !
                10 to 14.9 years                           !
                15 to 19.9 years                           3
                20 to 29.9 years                           4
                30 to 50 years                            18
                Over 50 years                             67
                Data not available                       	§.
                                         Total            100

 Source:   SCS Engineers.  1976.  Assessment of  industrial hazardous waste
          practices, leather tanning and finishing  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 (USEPA 1979). Although most tanneries are  over 50 years old,  the  few
 built recently have tended to be  through-the-blue  operations  located nearer
 the source  of hides  (SCS  Engineers 1976).  This reduces  the  need to  transport

                                        33

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unusable portions of hides great distances and also  improves  the tanner's
control over the curing process.  This also will  tend  to  remove the  beamhouse
and tanhouse operations, which produce the greatest  pollution load,  away from
traditional urban locations  to areas  where industry  wastes  can be more easily
accommodated.  New  beamhouse/tanhouse operations  of  this  sort have been opened
in Missouri and Texas  in the last few years.  These  new facilities also will
tend  to be larger than the traditional facilities, as  uniform production
techniques encourage mass production  tanning.

1.4.3 Raw Materials

      As a by-product  of the  meat industry, hides  and skins  represent only  3 to
6 percent of  the value of the live  animal (USEPA  1977b).  Therefore, the
demand for hides will not effect their  supply.  During the  1960's and 1970's,
there has been a rapid increase  in  the  supply of  cattlehides, which  account
for 84% of the hides  used by U.S tanners. Due  to rapid growth in the demand
for meat, the  cowhide supply has been steadily  and rapidly  increasing from
25.2  million  hides  in 1960 to more  than 42 million in 1976.  Even with the
occasional production slumps which  follow a  cyclical pattern  of building up
and reducing herds, the commitment  of the livestock industry  to long-term
growth assures the  tanning industry of  a continuously increasing supply of
hides for the  future.

      Despite this expanded supply of  domestically produced  hides, the U.S.
tanning industry has  not been able  to increase  its production due to the price
inflating effect of worldwide demand  for U.S. produced cattlehides.   Because
total hide production has fallen from its 1976  high while exports of raw
cattlehides continue  to  increase as a percentage  of  total hide production, the
actual net effect has  been a decrease in hides  available for  domestic leather
production (see Figure 6).

      While the supply  of cattlehides  has grown, the  supplies  of other types of
animal skins have been decreasing.  Calfskin supplies have been shrinking
drastically in the  U.S. with the exception of a temporary increase  from  1974
to 1977,  and are not expected to be a major factor in  the market  in  the future
(U.S.  Department of Commerce 1979).   Calfskin production declined 20% from 5.5

                                      34

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Figure  6.   Trends  in cost  and  availability  of cattlehides  for
      the U.S. market,  1969-1978.
                      Slaughter Decline, Export Pressure
                        forcing Cattiehide Prices Up
               Million hides                        Cants par pound
               50 ^M^H^^BBHMHHMIM^BBra  BO
               4O
               30
               20
               10
                     196970 71 72  73  74 75  76 77 78'

                  D CATTIEHIOE SHIPMENTS TO U.S. MARKET
                  D CATTLEHIPE EXPORTS
                  'Estimated
                  Source; U.S. D«p«rtm«nl of Agrieu&urt: BufMu of ttw
                  Industry Mid Trad* AdmmiatrKion IBO8D)
                                                         40
                                                         30
                                                         20
                                                         10
SOURCE:   U.S.  Department  of Commerce.   1979.  U.S.  industrial
           outlook.

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million in 1977 to 4.4 million in  1978, with 2.6 million of these hides
(59.1%) exported  (U.S. Department  of Commerce  1979).   Sheep and  lambskin
supplies have been declining  steadily  over the past  two decades, and  the
long-term prospect for sheepskins  from domestic sources indicates this will
continue.  Domestic  sheep  and lambskin production declined  14% from 6.27
million skins in  1977 to 5.5  million  in 1978,  with 1.2 million of these skins
exported.  Pigskin supplies may  increase,  however, due to the increasing  trend
for  removing skin before butchering.   Other skin sources are not used in  the
United States to  a great extent.

 1.4.4  Processes

      Identification  of  process trends in the leather tanning  industry is
 complicated  because  tanning continues to be practiced as  an art. The set of
 processes and procedures necessary to produce leather of  the  particular color,
 texture,  and working qualities desired by customers are  the guarded  secrets  of
 the trade,  and there is great reluctance on the part of  most  tanners  to make
 even minor changes in processes that might affect the quality of the finished
 product.   The concern with consistent product quality and the uncertainty of
 most tanners on how a particular process change may affect their product  make
 adoption of new processes  quite slow and the prediction of trends quite specu-
 lative.  The toxic nature  of many of the industry's wastes (e.g., highly
 alkaline unhairing waste,  chrome tanning liquor, and priority pollutant-based
 dyestuffs)  make the  most  effective treatment method elimination or control at
 the source.  For this reason, many of the process modifications which are
 being adopted by the leather tanning industry have as their sole or  primary
 purpose pollution control.  Those process trends primarily related to pollu-
 tion control are discussed in the next section.  Highlighted below are other
 process trends that are identified for the industry.

      •  Brine hide curing is currently favored over salt curing due  to the
         reduction in time and labor involved  in curing the hides and the
         benefits of cleaning the hides of blood, dirt, and manure before  they
         are delivered to the tanner.
      •  In order to improve the efficiency of  the industry, there are expected
         to be overall larger tanneries in the  future, which will process
         greater numbers of hides  in larger batches.
                                     36

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    •  Due to competition from synthetics,  there is  expected to be a con-
       tinued decrease in sole leather production which  is vegetable tanned.
       This follows  a long-standing  trend  toward more  chrome tanning and less
       vegetable tanning.

    •  Many tanneries (particularly  through-the-blue operations) have adopced
       the use of hide processors  for  some or  all of their wet processes.
       Hide processors offer an  advantage  in the handling of hides since
       washing, beamhouse,  and tanhouse  operations  can be carried out in the
       same vessel.

    •  Hair pulp unhairing  is increasing because  there are few markets
       for by-product hair  and because this process reduces  fine hair carry-
       over and requires less handling,  which  reduces  labor  costs.

    •  Many tanners  have eliminated  the solvent-based  finishes
       used to obtain a  high luster  surface on leather because  of  the asso-
       ciated hazards from fire  and  concern for employee safety.

    •  Some tanners  have begun to use an extremely  accurate  hide  splitting
       method  called "splitting  to weight."  It requires new equipment, but
       reduces the need  to shave hides to obtain uniform thickness and  pro-
       duces  a more  valuable split with a lower volume of shaving waste.


1.4.5   Pollution  Control


     Because the  leather tanning and finishing  industry has traditionally been
located in urban  areas,  many of its pollution problems have been passed on  for
the municipality  to handle.  Consequently,  the  job of  adopting modern pol-
lution control technology to many  of the serious environmental problems of  the

industry  has only begun  in  the last  two  decades.


     1.4.5.1  In-Plant Pollution Control


     As noted in the previous section,  the most efficient method for elimina-

ting pollutants from tannery wastes  and  in reducing the  volume of effluent  is
through reuse of water and  chemical  agents and through recovery of materials
which are normally wasted.   The  acceptance of  these la-plant pollution  control
measures is slow,  as is  the case with other process trends.  Typical In-plant

pollution control  measures  currently being investigated  by the  industry are
shown  in Table 1 along with their relative degree of acceptance in  a survey of
46 tanneries.  The key to industry acceptance  of  these processes  is the ability
to implement  them  without adverse effects  on leather quality.   The  processes
most favored  in this survey are  highlighted below (USEPA 1979).
                                     37

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   Table 1.   In-plant process treatment indicated on questionaire
        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

Liritafc 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

         3


         8


         4

         0
Number of Plants
Which Are or Will
 Be Implementing
 Process Changes

       0
       0

      13

       7

      13

      10

       3

      10

       5

       8


      13


      14

       5
SOURCE:  U. S. Environmental Protection Agency.  1979.  Preliminary draft
         development document for proposed effluent limitations guidelines
         and new source performance standards for the leather tanning and
         finishing industry.


*At least one plant has abandoned this system since these data were collected
 for the USEPA survey.

SOURCE:  Kenneth A. Dostal.  1979.  Memo, Kenneth Dostal, USEPA Region V, to
         Bob Pickett, USESA, Office of Environmental Review, 29 June 1979. 3 p.
                                     38

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    •  In recent years,  the hide processor  (modified  concrete mixer) and
       other processing  equipment have  been  found  to  be effective as a means
       of reducing  labor, handling, and water use.  The amount of new pro-
       cessing equipment  in use is  increasing, most widely  for washing the
       incoming hides  and for  beamhouse operations  in hair  pulp processes.  A
       few tanners  also  have used new equipment  for the through-the-blue
       tanning process.

    •  Lime is used in large quantities in  the beamhouse  for opening the hide
       structure and for unhairing.   It has  been found that lime solutions
       can be recycled many times  if  solids  are  removed and the solution is
       refortified.  By  reducing the  amount  of lime in the  effluent, the
       alkalinity of the waste and  the  volumes of  insoluble calcium sludges
       generated during  waste  treatment are  reduced.

    •  There are a  number of vegetable  tanneries that are using recycle
       systems to reduce the amounts  of tan liquor that are discharged  into
       the waste streams.  The Liritan  (Leather  Industries  Research Insti-
       tute, South  Africa)  process  employs  such  a technique by counter-
       current flow of tanning solution in  relation to the  hides.  There is
       little effluent,  but  some blowdown is necessary to prevent  the build-up
       of contaminants in the  tanning solution.   One  tannery  recovers this
       blowdown tan liquor,  concentrates  it in a triple  effect evaporator,
       and sells the concentrated  liquor.  Other tanneries  use this blowdown
       liquor in retanning operations.   However, the  trend  for recycle  of
       these solutions will be limited  by the availability  of  low cost  re-
       covery energy and a strong  market  for the recycled solution.

    •  Recycling, reuse, and  recovery of  chrome  tanning  solutions  are also
       being practiced in the  industry.  During  World War II,  the reuse of
       chrome tan  liquor was  common practice because of  the scarcity  of
       chromium salts.  Chrome tan liquor has been recycled for  use as  a
       pickle/pretan by fortifying it with acid  and salt.  This  has  also  been
       reused for tanning by removing the solids and adding more  chromium
       salts.   Spent chrome tan liquor is also used by some tanners  as  a
       retan  solution.  Recovery of chrome  from the waste stream is not being
       widely practiced.

    •  Large  volumes of wash water are used in a tannery for equipment  and
       process  washing.   Much of the water  used to wash incoming hides  can  be
       reused  if  solids are settled or screened out,  but this has been  less
       well  accepted than equipment washwater and process rinse  water reuse
       from later  steps in the tanning process.

    •  Waste  stream segregation is being implemented by most tanners  for
       reuse  of  process liquors, process solution recovery, and  improved
       waste  treatment efficiency.

    The  trend toward  implementation of in-plant water conservation and  pol-
lution  control technologies is likely to expand  in the future.  As chemical
costs  rise and regulatory requirements  continue  to tighten, tanners are likely
to find that control of  pollutants at their source, especially toxic and small


                                     39

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volume organics, is easier and less expensive than their removal from the
entire process waste stream.

     1.4.5.2  End-o£-Pipe Pollution Control

           Pretreatment
      The  need  for pretreatment  is based on the following factors:

      • Pollutants that are not removed by the publicly owned  treatment
        works  (POTW)  must be removed by pretreatment.
      • Pollutants that may cause treatment system upsets or hazards,  collec-
        tion system obstructions, or may be hazardous (e.g., sulfides) must  be
        removed by pretreatment.
      • NPDES permit control requirements imposed upon the POTW may  reflect
        stringent water quality criteria.
      • The load to the POTW secondary treatment units may need to be  reduced.
      • Pollutants must be removed that would render the POTW  sludge unfit
        for reuse or disposal.

      It is estimated that 90% of the tanners (who generate 75% of the  leather
 tanning and finishing industry's wastewater) discharge to municipal  sewer
 systems (USEPA 1979).  Of that number, 12% provide no pretreatment,  20%  pro-
 vide coarse screening only, and 68% provide some additional pretreatment.

      Many of the leather tanning industry's wastes are of such character or
 concentration that they require pretreatment as discussed above. As regula-
 tions for pretreatment of the industry's wastes become progressively more
 stringent, new tanneries discharging to municipal waste treatment systems will
 be required to implement progressively more sophisticated pretreatment measures.
 Future pretreatment technology  includes practically all of the viable treat-
 ment methods that have been examined for the leather tanning industry (see
 Section 3.2).   It is anticipated that the net effect of these stringent pre-
 treatment requirements will be  that new tanneries will find it increasingly
 attractive to construct and operate direct discharge waste treatment systems
 rather than pay for both sophisticated pretreatment and a municipal sewer
 charge.
                                       40

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          Secondary and Advanced Treatment

     Only 10% of existing tanneries have a direct discharge of wastewater.
All of these tanneries provide some form of biological treatment as indicated
below, but current and proposed regulatory requirements undoubtedly will
require a substantial upgrading of the industry's waste treatment technology,
since this generally has been found inadequate.

    Current level of waste  treatment  technology among discharging tanneries
          No preliminary  treatment                   0
          Preliminary  treatment  only                 0
          Secondary  treatment                      100
               Lagoon  or  other treatment           72
               Activated  sludge  treatment          28
               Physical /Chemical                Plant  Closed
 Source:   U.S.  Environmental Protection Agency.   1979.  Preliminary  draft
          development document for proposed effluent limitations guidelines
          and new source performance standards for the leather tanning and
          finishing industry.
 Because  of  the increasingly stringent limitations on industrial effluents, the
 specific trends will include a move away from lagoons to more reliable biological
 treatment in the form of extended aeration or activated sludge.  Upgrading
 biological  treatment (e.g., powdered activated carbon addition) and filtration
 of the final effluent also will become more common.

           Solid Waste Handling and Disposal

      Large volumes of potentially hazardous solid wastes are generated by the
 tanning industry.  Treatment and disposal of these hazardous materials have
 not generally been handled  properly by the industry  in the past.  For example,
 it is estimated that only  6% of the chrome waste generated by the industry in
 1974 was disposed in certified hazardous waste disposal sites, while the
 remainder was disposed  in  a variety of landfills,  lagoons, pits, ponds, and
 trenches.  With the adoption of strict national hazardous waste regulations,
                                      41

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the industry will be  forced either  to  reduce  its  hazardous waste  load or find
adequate  disposal sites  (SCS  Engineers 1976).

1.5  POLLUTION CONTROL REGULATIONS

1.5.1  Air  Pollution

     The  leather tanning and  finishing industry generally is  not  considered a
major  source of air pollutant emissions.   Therefore,  there are no national air
pollution performance standards  which  apply to atmospheric emissions from new
source leather tanning and finishing facilities.   In  the  absence  of Federal
emission  standards  for the industry, air  quality impacts  are  assessed based on
ambient air quality standards, and  applicable state and local standards.

     National  Ambient Air Quality Standards (NAAQS) (40 CFR 50) that specify
the ambient air quality  that  must be maintained in the United States are shown
in Table  2. Standards designated as primary are those necessary  to protect
the public  health with an adequate  margin of safety,  and  secondary standards
are those necessary to protect the  public welfare from any known  or anticipated
adverse effects of  air pollution.

     A combined Federal/state regulatory  program is designed  to achieve the
objectives  of  the Clean  Air Act  and NAAQS.   Each state must adopt and submit
to USEPA  a  State Implementation  Plan (SIP)  for maintaining and enforcing
primary and secondary air quality standards in Air Quality Control Regions.
USEPA  either approves the state's SIP  or  proposes and implements  an alternate
plan.  The  SIP's contain emission limits  which may vary within a  state due to
local  factors  such  as concentrations of industry and  population.  Because
SIP's  have  been subject  to frequent  revision,  it  is best  to verify the status
of the SIP  requirements  before applying them.

     There  are  two  alternate  programs  requiring preconstruction approval of
industrial  air  pollution abatement  systems.  These are the Prevention of
Significant Deterioration (PSD)  Program which  applies  to  areas in compliance
with NAAQS and  the  Nonattainment  Program  for areas which  are  in violation of
NAAQS.   In  1974, USEPA issued  regulations for  the PSD  Program under the 1970

                                     42

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           Table 2.

     Emission

Sulfur dioxide
Applicable Federal ambient air quality standards.

                                           Secondary Standard*
Particulate matter
Nitrogen dioxide**


Ozone***


Carbon monoxide
Lead
      Primary Standard*

 80 yg/m  annual
    arithmetic mean
        3
365 yg/m  maximum
    24-hour concentration
        3
 75 yg/m  annual
    geometric mean

260 yg/m  maximum
    24-hour concentration
      100 yg/m  annual
          arithmetic mean

      240 yg/m  maximum
          1-hour concentration
              3
       10 mg/m  (9 ppm) maximum
          8-hour concentration
              3
       40 mg/m  (35 ppm) maximum
          1-hour concentration
              2
      1.5 yg/m  (3-month average)
                                      .,300 yg/m  maximum
                                           3-hour concentration
150 yg/m  maximum
    24-hour concentration

 60 yg/m  annual geometric mean
    as guide in assessing
    implementation plans
        3
100 yg/m  annual
    arithmetic mean
        3
240 yg/m  maximum
    1-hour concentration

 10 mg/m  (9 ppm) maximum
    8-hour concentration
        3
 40 mg/m  (35 ppm) maximum
    1-hour concentration
        3
1.5 yg/m  (3-month average)
*   For any standard other than annual, the maximum allowable concentration may be exceeded
    for the prescribed period once each year.

**  Within one year after the date of the enactment of the Clean Air Act Amendments of 1977
    (PL 95-95), the USEPA Administrator shall promulgate a national primary ambient air quality
    standard for NO, concentrations over a period of not more than 3 hours unless, based on the
    criteria issued under Section 108(c), he finds that there is no significant evidence that
    such a standard for such a period is requisite to protect public health.

*** For ozone the maximum allowable concentration may be exceeded one day each year, but on that
    day it may exceed the maximum hourly concentration more than once.
 SOURCE:  40  CFR 50.

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version of the Clean Air Act  (Public Law  90-604).  These  regulations estab-
lished a plan for  protecting  areas  that possess air  quality  which is cleaner
than  the National  Ambient Air Quality  Standards.   The PSD Program components
include:

      •  a  classification system for areas of the  country  meeting NAAQS;
      •  limitations on the  increase in concentration of pollutants  above
        baseline conditions;
      •  Best Available Control Technology requirement for large sources; and
      •  preconstruction review and approval by permit of  new source air pol-
         lution facility abatement programs.

      Under USEPA's PSD regulatory plan, all areas of the  nation are designated
 as one  of  three classes.  The plan permits specified numerical increments  of
 air pollution increases from major stationary sources for each class,  up  to a
 level considered to be significant for that area  (Table 3).   Class  I provides
 extraordinary protection from air quality deterioration and permits only  minor
 increases  in air pollution levels.  Under this concept, virtually  any  increase
 in air pollution in these pristine areas is considered significant.  Class II
 increments permit increases in air pollution levels that would accompany
 well-controlled growth.  Class III increments permit increases in  air pollu-
 tion levels up to the NAAQS.

      Sections 160 - 169 were added to the Act by  the Clean Air Act Amendments
 of 1977.   These Amendments adopted the basic concept of  the above  administra-
 tively developed procedure of allowing incremental  increases in air pollutants
 by class.   Through these Amendments, Congress also  provided a mechanism to
 apply a practical adverse impact test which did not exist in the USEPA regula-
 tions previously.

      The PSD requirements of 1974 apply only to two pollutants:  total sus-
 pended  particulates (TSP) and sulfur dioxide (S02).  However, Section 166
 requires  USEPA to promulgate PSD regulations by 7 August 1980 which address
 nitrogen oxides, hydrocarbons, carbon monoxide, and photochemical  oxidants,
 including  use of increments or other effective control strategies.  For these
 additional pollutants, states may adopt non-increment control strategies
                                        44

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                  Table 3.  PSD increments:  maximum
                       allowable Increase by class.


                         Class I  Class,II  Class Til
     Pollutant*          (yg/m )  (ye/m )    (yg/m3)

Particulate Matter:

  Annual geometric mean      5        19         37

  24-hour maximum           10        37         75


Sulfur dioxide:

  Annual arithmetic mean     2        20         40

  24-hour maximum            5**      91        182

  3-hour maximum            25**     512        700
*  Other pollutants for which PSD regulations will be promulgated are to
   include hydrocarbons, carbon monoxide, photochemical oxidants, and
   nitrogen oxides.

** A variance may be allowed to exceed each of these increments on 18 days
   per year, subject to limiting 24-hour increments of 36 yg/m  for low
   terrain and 62 yg/m  for high terrain and 3-hour increments of 130
   yg/m3 for low terrain and 221 yg/m3 for high terrain.  To obtain such a
   variance both state and Federal approval is required.

SOURCE:  Public Law 95-95.  1977.  Clean Air Act Amendments of 1977,
         Part C, Subpart 1, Section 163.
                                     45

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which, if taken as a whole, accomplish the purposes of PSD policy set forth in
Section 160.

     The 1977 Amendments designate certain Federal  lands as Class I, including
all international parks, national memorial parks, and national wilderness
areas which exceed 5,000 acres, and national parks  which exceed 6,000 acres.
This constitutes 158 areas which may not be redesignated to another class
through state or administrative action.  The remaining areas of the country
have been initially designated Class II.  Within  this Class II category,
certain Federal lands  over 10,000 acres  (national primitive areas, national
wild and scenic rivers, national wildlife refuges,  national seashores and
lakeshores, and new national park and wilderness  areas) established after 7
August 1977 will be Class II "floor areas" ineligible for redesignation to
Class III.

     The general redesignation responsibility  lies  with the states.  The
Federal  land manager has an advisory role  for  redesignation to the appropriate
state and to Congress.  Redesignation by Congress will require the normal
legislative process of committee hearings, floor  debate, and action.  In order
for a state to redesignate areas, the detailed process  (outlined in Section
164(b) of the 1977 Amendments) would include an analysis of the health, environ-
mental, economic, social, and energy effects of the proposed redesignation
which would be discussed at a public hearing.

     In theory, all new source tanneries would be subject  to complete PSD
review if they obtain  their air quality  permits after March 1, 1978, commence
construction after March 19, 1978, or have potential (before treatment) emis-
sions in excess of 250 tons/year of certain pollutants.  Full PSD  review
requires analysis of effect on air quality increments, application of Best
Available Technology,  and a comprehensive monitoring program.  In  practice,
however, small sources of the designated air pollutants  (less than 50 tons/
year, 1000 Ibs/day, or 100 Ibs/hour after abatement) are required  only  to
apply for and obtain a preconstruction permit  unless they  would  impact  a Class
I area.  Therefore most new source tanneries should not have to  go through  the
whole PSD review.  A similar type of exemption exists for  small  sources (less
than 50 tons/year after abatement) in non-attainment areas unless  the pollutant
                                    46

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emitted is the cause for non-attainment.  In that case, a permit would be
issued only after controls (offsets) were obtained by the new source from
existing emission sources sufficient to effect a net reduction of the non-
attainment pollutant.

1.5.2  Water Pollution

     The Federal Water Pollution Control Act (FWPCA) Amendments of 1972 estab-
lished two major, interrelated procedures for controlling industrial effluents
from new sources, and specifically included tanneries and related facilities
in the list of affected source categories.  The principal mechanism for dis-
charge regulation is the National Pollutant Discharge Elimination System
(NPDES) permit.  The other provision is the New Source Performance Standard
(NSPS).  The Clean Water Act of 1977 (P.L. 95-217), which amends P.L. 92-500,
made no change in these basic procedures.

     The NPDES permit, authorized by Section 402 of FWPCA, prescribes the
conditions under which effluents may be discharged to surface waters.  Issuance
of a New Source NPDES permit is considered a significant Federal action and is
subject to the requirements of the National Environmental Policy Act (NEPA).
The conditions applicable to new or expanded tanneries will be in accordance
with NSPS, adopted by USEPA pursuant to Section 306, and pretreatment stan-
dards promulgated to implement Section 307(b).  Different standards will be
applicable nationwide depending on the subcategory of tannery under considera-
tion.  Stricter effluent limitations may be applied on a site-specific basis
if required to achieve water quality standards.

     On 9 April 1974, USEPA published regulations specifying guidelines and
New Source Performance Standards for the Leather Tanning and Finishing Point
Source Category which were to become effective on 4 June 1974 (40 CFR 425: 39
FR 15696).  However, these regulations were remanded and USEPA is in the
process of developing new regulations for the industry which have been pro-
posed on 2 July 1979.

     The basis for New Source Performance Standards (NSPS) under Section 306
of the Act is the best available demonstrated control technology (BADCT).  New
                                      47

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plants have  the opportunity to design  the best  and most  efficient  leather
tanning processes and wastewater  treatment technologies  and,  therefore,
Congress  directed USEPA to consider  the best  demonstrated  process  changes,
in-plant  controls,  and  end-of-pipe treatment  technologies  which reduce
pollution to the maximum  extent  feasible.  The  effluent  limitations  estab-
lished for new sources  in each of the  seven  subcategories  of  the industry are
shown in  Table 4.   It might be noted that since removal  of toxic pollutants is
of  major  concern  in the leather  tanning and  finishing industry, the  effluent
limitations  for BAT (Best Available  Technology  Economically Achievable), which
must  be attained by all existing tanneries by 1 July 1984,  are the same as
NSPS.

      New  sources  that discharge  wastewater to publicly owned  treatment works
 (POTW) are required to  comply with USEPA's pretreatment  regulations, issued in
the 26 June  1978,  Federal Register  (40 CFR 403).  These  regulations  stipulate
that  certain POTW's, categorized by  size and  influent characteristics, develop
POTW Pretreatment  Programs.   These programs  are intended to prevent  the intro-
duction of pollutants by  industrial  users that  would interfere with  the opera-
tion of treatment  works,  would pass  through  treatment works,  or would adversely
affect opportunities to recycle  and  reclaim  wastewaters  and sludges.

      Regardless of  specific limitations required  by  the  Pretreatment Programs,
the regulations (Section  403.5)  state  that the  following may  not be  introduced
into  a POTW:

      •  pollutants  which  create  a fire or explosion  hazard  in the POTW;
      •  pollutants  which  will cause  corrosive structural damage to the
        POTW,  but in no case discharges with  pH lower than 5.0, unless the
        works  is specifically designed to accomodate such  discharges;
      •  solid  or viscous  pollutants  in amounts  which cause  obstruction
        to the flow in  sewers, or other interference with  the operation of the
        POTW;  and
      •  any  pollutant,  including  oxygen-demanding pollutants, released in
        a  discharge  of  such volume or  strength  as to cause  interference in the
        POTW.

In addition, there  is a restriction  on thermal  discharges  that becomes effec-
tive  in June 1981.

                                    48

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                             Table 4.  Proposed new source performance standards (NSPS) and pretreatment standards for new
                                  sources (PSNS) for the seven subcategories of the leather tanning and finishing Industry.
Subcategory
Hair Pulp,
Chrome Tan,
Retan - Wet
Finish
    2
Hair Save,
Chrome Tan,
Retan - Wet
Finish
Hair Save,
Non- Chrome
Tan, Retan -
Wet Finish

    4
Retan - Wet
Finish
 No Beamhouse
                    BOD.
            Maximum pollutant discharge for any one day,
               kg/1000 Kg (lb/1000 lb-1 of raw material
                Oil &   Total
                          COD  TSS  Grease  Chrome TKM  Ammonia  Phenol  Sulfide  pH

                    2.1   9.5  2.5   0.91   0.053  2.3    0.77   0.015     0.0    6-9
                                                                                         BOD
Average for thirty consecutive days not to be exceeded,
   ky/1000 kn  Clb/1000 Ib) of raw material	
         Oil &   Total
                                                                        1  COD  TSS  Grease  Chrome TKN  Ammonia  Phenol  Sulfide  pH
                                                                     0.61  5.8  0.70  0.26    0.015 0.66   0.22   0.0043    0.0    6-9
2.3  10.0  2.6   1.0    0.053  2.4    0.81   0.016     0.0    6-9    0.65  6.2  0.74  0.28    0.015 0.69   0.23   0.0046    0.0    6-9
                    1.6   7.3  1.9   0.70   0.039  1.8    0.60   0.012     0.0    6-9    0.47  4.5  0.54  0.20    0.0110.51   0.17   0.0034    0.0    6-9
0.81  3.5  0.91  0.35   0.018  0.84   0.28   0.0056    0.0    6-9    0.23  2.2  0.26  0.10    0.005 0.24   0.081  0.0016    0.0    6-9



1.4   6.2  1.6   0.60   0.034  1.5    0.49   0.010     0.0    6-9    0.40  3.8  0.46  0.17    0.00960.43   0.14   0.0029    0.0    6-9
     6
 Through-
 the-Blue
 Shearling
1.5   6.8  1.8   0.67   0.035  1.6    0.56   0.011     0.0    6-9    0.44  4.2  0.50  0.19    0.0100.47   0.16   0.0031    0.0    6-9



6.7   29.8  7.7   2.9    0.16   7.4    2.4    0.049     0.0    6-9    1.9  18.0  2.2   0.83    0.0462.1    0.69   0.014     0.0    6-9
 Source:  U. S. Environmental Protection Agency.   1979.   Preliminary draft development  docun,Cnt  for proposed effluent limitations  guidelines  and new
          source performance standards for the leather tanning and finishing industry.

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     Among the pollutants in the raw waste from tanneries, BOD , TSS, oil and
grease, total chromium, sulfide, ammonia, and other toxic priority pollutants
are present in sufficient concentrations to represent potential problems of
pollutant pass-through or sludge disposal at the POTW.  Due to this, Pretreat-
ment Standards for New Sources  (PSNS) have been developed in the development
document which will require removal of toxics and will regulate all of the
same pollutants as covered by BAT and NSPS.  Since the level of technology
required to achieve PSNS and NSPS will be the same, it is anticipated that new
tanneries will be encouraged to treat their own wastes subject to NSPS and
obtain an NPDES permit for discharge directly to surface waters.  The PSNS
concentration limitations for all subcategories are listed below and the pro-
duction-based mass limitations  for each subcategory are identical to those
listed in Table 4.

  PSNS Concentration Limits Proposed for Leather Tanning (All Subcategories)



BOD
COD
TSS
Oil and Grease
Total Chromium
TKN
Ammonia
Phenol
Sulfide
pH Within
Maximum
any one day
(mg/1)
70
320
90
35
2.0
70
35
1.0
0.0
the range of 6.0 to 9.0 at
Average for
consecutive
(mg/1)
20
195
25
10
0.5
20
10
0.25
—
all times.
30
days











SOURCE:  U.S. Environmental Protection Agency.  1979.  Preliminary draft
         development document for proposed effluent limitations guidelines
         and new  source performance standards for the leather tanning and
         finishing industry.

Since new sources discharging to POTW's do not require NPDES permits, they are
not subject to NEPA under Section 511(c)(1) of the Federal Water Pollution
Control Act, as amended by the Clean Water Act of 1977.
                                      50

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     NPDES permits also impose special conditions beyond the effluent limi-
tations stipulated, such as schedules of compliance and treatment standards.
Once tanneries are constructed in conformance with all applicable standards of
performance, however, they are relieved by Section 306(d) from meeting any
more stringent standards of performance for 10 years or during the period of
depreciation or amortization, whichever ends first.  This guarantee does not
extend, however, to toxic effluent standards adopted under Section 307(a),
which can be added to the NPDES permit when they are promulgated.  USEPA
proposes to control the discharge of toxics from the leather tanning and
finishing industry by regulating two toxic pollutants used as indicator pol-
lutants:  phenol and chromium.  USEPA has found that the treatment technology
required to remove phenol and chromium as well as conventional and non-conven-
tional pollutants also effectively controls the other priority toxic pollutants
found in tannery waste.  Therefore, the effectiveness of toxic pollutant
control can be assessed by the monitoring of these indicator pollutants without
the expense and technical difficulties with analysis for many of the complex
organic toxic pollutants.

     As encouraged by P.L. 92-500, many states have qualified to administer
their own NPDES permit programs.  The major difference  in obtaining an NPDES
permit through approved state programs rather than the  Federal NPDES permit
program is that the Act does not extend the NEPA environmental impact assess-
ment requirements  to state programs.  However, over 50  percent of  the states
have enacted NEPA-type legislation and it is likely that new tanneries or
major expansions of existing tanneries will come under  increased environmental
review.  Because the scope of the implementing regulations varies  considerably,
current information on prevailing requirements should be obtained  early in the
planning process from the permitting authority in the appropriate  jurisdiction.

     1.5.2.1  Best Available Technology  (BAT)

     The effluent  limitations which must be achieved by July 1,  1984 for
existing facilities are not based on an average of the  best performance within
an  industrial category.   Instead, they are based on the very best  control and
treatment technology employed by a specific point source within  the  industrial
category or subcategory,  or by another  industry whose technology is readily

                                        51

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transferable.  The analysis of control measures and practices to eliminate the
discharge of pollutants also must consider the cost of such measures.  BAT
emphasizes in-g>rocess controls as well as end-of-pipe treatment improvements.
Other considerations include:  manufacturing processes; age and size of facil-
ities; location of manufacturing facilities; process changes; engineering
aspects of control technologies; cost of technology to achieve control levels;
and non-water quality environmental  impacts, including energy.

     BAT technology uses BPT technology as a basis for further improvements.
This includes primary coagulation-sedimentation and high solids extended
aeration-activated sludge  system with nitrification.  Additional technologies
for BAT include:

     •  In-Plant  Control and Preliminary Treatment
          Water conservation and reuse to reduce flow
          Stream  segregation for preliminary treatment
          Ammonia substitution in deliming
          Chrome  recovery  and reuse
          Sulfide liquor reuse followed by catalytic oxidation of
               residual sulfide
          Fine screening of segregated streams
          Flue gas carbonation and sedimentation for beamhouse
               wastewaters
     •  End-of-Pipe Treatment
          Addition of powdered activated carbon  (PAC)
               to upgrade  extended aeration-activated sludge
          Multimedia filtration
          Granular activated carbon  columns
          Physical/chemical treatment (Chappel Process)

     The anticipated performance associated with these  technologies  is in-
cluded  in the Development  Document for this industry  (USEPA 1979).

     1.5.2.2 New Source Performance Standards  (NSPS)

     The basis for NSPS is the best  available demonstrated control  technology
(BADCT).  New plants have  the opportunity  to design  the best and  most efficient
leather tanning processes  and wastewater treatment  technologies.  A major
difference between NSPS and BAT is that the evaluation  of  NSPS  does not con-
sider cost.  For  the Leather Tanning and Finishing  Industry,  the  effluent
limits for NSPS are identical to BAT.
                                    52

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     1.5.2.3  Regulated Pollutants


     The BAT and NSPS effluent limitations proposed for the leather tanning

industry focus on three major groups of pollutants (USEPA 1979):

     •  Indicator pollutants.  The difficulties of toxic pollutant analyses
        have prompted USEPA to propose a new method of regulating selected
        toxic pollutants.  Historical data and inexpensive analytical methods
        are limited for certain toxic pollutants.  Therefore, USEPA is pro-
        posing numerical limitations on "indicator" pollutants; these include
        BOD , COD, TSS, oil and grease, TKN, ammonia, sulfides, total chromium,
        and5total phenol.  The data available to USEPA revealed that when
        these indicator pollutants were controlled, the concentrations of
        toxic pollutants were significantly lower  than when indicator pol-
        lutants were present in high concentrations.

     •  Non-toxic, non-conventional pollutants.  The non-toxic non-conventional
        pollutants limited by BAT and NSPS include total Kjeldahl nitrogen^
        (TKN), ammonia, and sulfide.  These pollutants serve as "indicator"
        pollutants for the removal of toxic pollutants.  These pollutants are
        subject to numerical  limitations  expressed in  Ibs per  1000  Ibs of  raw
        material.

     «  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  USEPA has  adopted the control  of  "indicator"
        pollutants as  the  basis for  controlling  toxic  pollutants  other than
        chromium  and phenol,  no effluent  limitations are recommended  for  any
        toxic pollutants other  than  chromium and  phenol.   At  the same time,
        USEPA also is  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-trichloro-
        phenol,  50  yg/1;  pentachlorophenol,  25  yg/1;  lead,  250 yg/1;  zinc, 250
        yg/1; cyanide,  500 yg/1.

      1.5.2.4  Pretreatment Standards for New Sources  (PSNS)


      The  effluent limitations that must be achieved  by new sources in the

 leather tanning and  finishing industry that discharge into a POTW are termed

 pretreatment standards for new sources (PSNS).   Section 307(b) of the Act

 requires  USEPA to promulgate pretreatment standards  to prevent the discharge
 of pollutants which pass through, interfere with, or are otherwise incompatible

 with the operation of publicly owned treatment works (POTW).  The Act also
 requires pretreatment for pollutants, such as heavy metals, that limit POTW

 sludge management alternatives, including the beneficial use of sludges  on
                                       53

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agricultural lands.  The pretreatment standards are to be technology-based,
analogous to the best available technology for removal of toxic pollutants.
The considerations in developing PSNS are the same as those enumerated for BAT
(Section 1.5.2.1).

     The candidate control technologies for meeting PSNS include (USEPA 1979):

     •  Water conservation and reuse to reduce flow.
     •  Stream segregation for preliminary treatment.
     •  Ammonia substitution in deliming.
     •  Chrome recovery and reuse.
     •  Sulfide liquor reuse followed by catalytic oxidation of residual
          sulfide.
     •  Fine screening of segregated streams.
     •  Flue gas carbonation and sedimentation for beamhouse
          wastewaters.
     •  Equalization  of combined streams followed by primary
          coagulation-sedimentation.
     •  Activated sludge  (high solids extended aeration with
          nitrification).
     •  Powdered activated carbon  (PAC) addition to upgrade extended
          aeration-activated sludge.
     •  Media filtration.
     •  Physical/chemical treatment  (Chappel Process).

     These  PSNS technologies essentially are identical to BAT because pass
through of  toxics in  the POTW and presence of toxics in the POTW sludges may
still be of concern.  This requirement will encourage new facilities to treat
wastewaters subject to NSPS for direct discharge.

     1.5.2.5  Best Conventional Pollutant Control Technology  (BCT)

     BCT was established for existing industrial point sources that discharge
conventional pollutants.  BCT is not an additional limitation but replaced BAT
for the control of conventional pollutants.  However, BAT still applies for
all nonconventional and toxic pollutants.  The limitations established by BCT
must consider the cost reasonableness of conventional pollutant reduction by
the industry versus reduction by the POTW.  Conventional pollutants have been
defined to include BOD, TSS, fecal coliform, and pH, with COD, oil and grease,
and phosphorus also proposed by USEPA as conventional pollutants (USEPA 1979).
For this industry, USEPA is proposing that the conventional "indicator" pollut-
ants (i.e., BOD, COD, TSS, oil and grease) be considered instead as toxic
                                     54

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pollutants and therefore be regulated by BAT so that the cost reasonableness
test would not apply.  This definition would be applicable unless the industry
can prove that the toxics, for which these conventional pollutants serve as
indicators, are not present in the wastewater.

     The BCT cost test was applied to proposed removal of conventional pollut-
ants associated with BAT technology required for toxic pollutant control
(USEPA 1979).  The conclusion from applying this test was that effluent limits
for conventional pollutants using BAT technology also meet the BCT cost test.
Therefore, the BCT effluent limits for conventional pollutants (i.e., BOD,
TSS, pH, COD, oil and grease) and associated control technology are the same
as those determined for the BAT  regulation  (USEPA  1979).

1.5.3.  Solid Wastes

     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  (USEPA 1979).

     Some  attempts have been made  to dewater sludges  prior  to ultimate  dis-
posal, with varying success.   The  three  principal  dewatering techniques  in-
clude 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  also has
been successful in  some areas.   This is  particularly  attractive to smaller
facilities where  land  area is  available  (USEPA 1979).

     Conditioning and  stabilizing a  mixed domestic and tannery sludge  using
heat  treatment processes  has  been employed where about 80%  of the waste flow
is  tannery waste.  Such heat  treatment or similar sludge destruction process
provides a stable end product from a biological standpoint.   These  stabilized
sludges  can  then  be incorporated into a landfill or spread  on the land.  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
                                         55

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trivalent chromium may be oxidized to the hexavalent form.  Apparently, the
trivalent chromium is converted through the high temperature, high pressure,
high pH, and the oxidizing environment of the heat treatment process (USEPA
1979).

     Chromium reuse reduces the levels of chromium in  the sludge.  Disposal of
sludge containing these  lower residual quantities of chromium in a sanitary
landfill will minimize any environmental problems (DSEPA 1979).

     Prior  to dewatering in mechanical equipment, sludge is normally con-
ditioned by use  of ferric 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% dry solids.  Plate and frame filter presses
have been found  to produce cakes  of 40 to 50% dry solids.  The higher capital
cost of filter presses may be quickly offset by lower  hauling and disposal
costs where landfills are located great distances from the tannery or the POTW
 (USEPA  1979).

     Some sludge is disposed of on the land, taking advantage of its lime
content for agricultural purposes.  One disadvantage of this type of disposal
practice is the  potential toxic effects of chromium or other constituents on
plants, ground water, and surface  water supplies.  Lagoons for dewatering have
some limited uses.  In humid areas where rainfall approximates or exceeds
evaporation, such application is  not completely satisfactory.  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
(USEPA 1979).

     Under  the Resource  Conservation and Recovery Act  (RCRA) passed by Con-
gress in 1976, solid wastes are divided into two broad categories for the
purpose of  regulation, namely hazardous wastes and other solid wastes.  Final
                                       56

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regulations for implementation of this statute have not been promulgated,  but
they have been proposed  (FR 58946-59028, 18 December 1978).  Generally this
program will standardize the criteria for construction of landfills for non-
hazardous solid wastes and establish a stringent permit program and manifest
system that will account for hazardous wastes from generation to final dis-
posal.

     Under the proposed  regulations, wastes may be judged hazardous by four
criteria:  ignitability, corrosiveness, reactivity, and toxicity (40 CFR
250.13, proposed).  Because the  leather tanning and finishing industry gener-
ates large quantities of corrosive, toxic, and reactive wastes, four waste
streams have been defined as hazardous  (40 CFR 250.14, proposed):

     •  wastewater treatment sludge from chrome tannery and beamhouse/tanhouse
        operations;
     •  wastewater treatment screenings from sheepskin tannery, split  tan-
        nery, and retan/finish operations;
     •  trimmings and shavings from leather tanning and finishing, chrome
        tannery, split tannery,  beamhouse/tanhouse, and retan/finish opera-
        tions; and
     •  wastewater treatment sludge from unhairing operations.

In  their present form the proposed regulations will require that every load of
hazardous waste be tracked at the tannery  through the hands of each trans-
porter and then to final disposal at an approved disposal  site.  The proposed
regulations also require chemical analysis  of the wastes,  use of appropriate
containers, submission of reports, and  monitoring and  inspection of disposal
sites.  The design as well as the operation of hazardous wastes disposal sites
will be regulated also.

      In general, recovery or disposal of non-hazardous  tannery wastes  in an
approved sanitary landfill will  be required under a state  regulatory  program,
with  new open  dumps  prohibited.   Existing  state solid  and  hazardous waste
disposal regulations  will be superseded unless they meet or exceed the Federal
standards.
                                      57

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                        2.0  IMPACT IDENTIFICATION

     The following discussions will identify the major pollutant sources for
the leather tanning industry.  The pollutant impact will be discussed for each
of the impact media.

2.1  AIR

     Emissions have not been found to be a major environmental impact of the
leather tanning industry, and there are limited data to quantify the genera-
tion of these pollutants.  Estimates of the quantity of buffing dust and
finishing solvents generated by some subcategories are available in the
hazardous waste assessment for the industry (SCS Engineers 1976).  These are
summarized in Table 5.  The established and potential sources for emissions
that should be addressed by a new source tannery would be expected to include:

     •  Beamhouse operation - sulfides from the unhairing process.
     •  Tanning operation - solvents from the degreasing recovery system.
     •  Finishing operation - dust from the buffing operation and solvents
        from spray finishes.
     •  Auxiliary support equipment - emissions from boilers and pollution
        control equipment.

Odor potential also should be identified in terms of possible sources (e.g.,
sulfides from unhairing) and their impacts on surrounding areas.  Due to the
large quantities of putrescible material handled by a tannery, odor problems
also may develop if scraps, screenings, sludge, and similar materials are not:
quickly removed and disposed.

2.2  WATER

     The following wastewater parameters are of major pollutional significance
for the leather tanning and finishing industry (USEPA 1979):
                                     58

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      Table 5.  Emissions from the finishing operation
          of various subcategories of the leather
          tanning and finishing industry.
     Subcategory              Buffing Dust(l)    Finishing Solvents

1.  Hair pulp/chrome                25                  450
    tan/retan-
    wet finish

3.  Hair save/non-chrome            90
    tan/retan-wet finish

4.  Retan-wet finish                25                  450

6.  Unhair/chrome tan
    (through-the-blue)

*   Sheepskin Tannery               50

*   Split Tannery                  180

*   Leather Finisher                10                  450
*   Subcategory used  for  hazardous waste assessment but not
    designated for  effluent  guidelines.

(1) All estimates appear  as  dry  lbs/1000 equivalent hides where
    equivalent hide weighs approximately 50 Ibs.

SOURCE:   SCS  Engineers.   1976.   Assessment of industrial hazardous
          waste practices, leather tanning and finishing industry.
                                  59

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          Biochemical Oxygen Demand
          Chemical Oxygen Demand
          Total Chromium
          Oil and Grease
          Sulfide
          Total Suspended Solids (TSS)
          Nitrogen Content  (Ammonia Nitrogen and
               Total Kjeldahl Nitrogen)
          Phenols
          pH and Alkalinity

Wastewater parameters of minor significance are:

          Total Dissolved Solids
          Chlorides
          Total Volatile Solids
          Nitrates and Nitrites
          Fecal Coliforms

Priority  pollutants of significance are:

          Organics
            Volatile
            Semi-Volatile
              Basic/Neutral Fraction
              Acidic Fraction

          Inorganics
            Cyanide
            Metals

          Pesticides
                                     60

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2.2.1  Wastewater Generation and Characteristics


     Wastewater streams generated by the leather tanning and finishing in-

dustry are highly variable and process dependent.  In view of the numerous

modifications that now exist to the basic processes described in Section 1.2,

the specific nature of the wastewater for the New Source tannery must be

carefully documented and specifically related to the processes anticipated

under actual operating conditions.


     Process waste stream characterization for  the industry should address the

following waste materials and  pollutant  indicators.


     •  Beamhouse Operation

        Hair                       High  pH
        Manure                     Sulfides
        Protein                    Grease
        Salt                       Nitrogen
        Flesh
        Hide trimmings

     •  Tanhouse Operation

        Dyes (complex organics)    Low  pH
        Degraded proteins          High chrome
        Salt                       Ammonia
        Dissolved  organics         Color

Retan,  color,  and  fatliquoring operation wastewater would be similar in nature

 to tanhouse operation wastewaters, and  should be reflected in wastewater

 estimates by a New Source tannery applicant.  Finishing operations  are usually

 dry, but  liquid wastes  could be generated by dust control equipment (e.g.,  wet

 scrubbers).


      The  industry's wastewaters are characterized by the following  major

 pollutants:

      ,  Biochemical oxygen demand (BOD).  In most leather tannery wastewaters,
         the BOD derives principally from organic material, such as  dissolved
         or "pulped" 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.
                                        61

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The BOD a waste exerts will reduce the dissolved oxygen resources of a
body of water.  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 detri-
mental to fish populations, fish growth rate, and organisms used as
fish food.  A total lack of oxygen 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 asso-
ciated 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.

Chemical oxygen demand.  Tannery wastewaters contribute to high COD
concentrations due to extraneous hide substance, manure, complex
organic and inorganic process chemicals, dyes, and vegetable tannins.

The COD test measures pollutants more resistant  to biological oxida-
tion than the BOD test includes.  These pollutants are of increasing
interest and concern because of the continuing oxygen demand they
exert and their potential health effects.   Some  pollutants measured by
the COD test have been found to have carcinogenic, mutagenic, and
similar adverse effects, either singly or  in combination.  The  long
life of these pollutants in the environment, the difficulty  in  re-
moving  them by commonly used systems of water purification,  and the
potential for chlorination converting them into  even more hazardous
materials magnifies their significance.

Total  suspended solids  (TSS) .  The  washing, unhairing,  shearing,  and
finishing operations  are the primary  sources.

Suspended solids  include both  organic and  inorganic  materials.   The
inorganic compounds  include  sand,  silt, and clay.   The organic  fraction
includes  such materials as  grease,  oil, and animal and vegetable waste
products.   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.

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.
                                 62

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•  Oil and Grease (0 & G) .  This is generated most significantly when
   pigskins and sheepskins are processed.  Other significant sources are
   from the soaking, fleshing, and fatliquoring processes.

   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 waterfowl.  Oil
   emulsions may adhere to the gills of fish, causing suffocation, and
   may taint the flesh of fish microorganisms that were exposed to waste
   oil.  Oil deposits in  the bottom sediments of water can serve to
   inhibit normal benthic growth.  Oil and grease also exert an oxygen
   demand in the natural  environment.

   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.

•  Chrome.  Chrome is generated from the chrome tanning process and
   subsequent wet processing steps.  Trivalent chrome is the only form
   normally present, since hexavalent chrome use in tanneries is prac-
   tically non-existent.

   Chromium can produce lung tumors when inhaled and induces skin sensi-
   tizations.  Large doses of chromates have corrosive effects on the
   intestinal tract and can cause inflammation of the kidneys.  A minimum
   level for the chromate ion that has no effect on man has not been
   determined.  The toxicity of chromium salts to fish and other aquatic
   life varies widely with the species, temperature, pH, valence of the
   chromium, and synergistic or antagonistic effects, especially those of
   hard water.  Fish appear to be relatively tolerant of chromium, but
   some aquatic invertebrates are quite sensitive,

•  Sulfide.  This is introduced in the form of sharpeners in the un-
   hairing process.

   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" corro-
   sion and corrosion of  equipment in POTW.  At higher concentrations
   this gas can be lethal to operation and maintenance personnel in
   sewers, and at POTW headworks, primary treatment, and sludge de-
   watering 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.

•  Nitrogen (total Kjeldahl nitrogen  (TKN) and ammonia).  Both nitrogen
   forms are generated in conjunction with the unhairing and bating
   processes.
                                  63

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   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 signif-
   icant 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.

   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.   A significant oxygen demand can result
   from the microbial oxidation of ammonia.

•  Phenol.  Phenol and substituted phenolics are generated mainly in
   conjunction with coloring of tanned hides.  These sources may include
   biocides (e.g., pentachlorophenol; 2,4,5 trichlorophenol), synthetic
   and natural vegetable tannins, carriers for dyes, and a number of
   other adverse sources all of which contribute to significant levels of
   phenol in raw wastewaters.

   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.  Phenolic compounds may
   adversely affect fish by a direct toxic action or by imparting a taste
   to the 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; it appears to have a toxic threshold of 0.1-15 mg/1.

   The human ingestion of a concentrated phenol solution results in
   severe pain, renal irritation, shock, and possibly death.  A total
   dose of 1.5 grams may be fatal.  Phenols can be metabolized and
   oxidized in waste treatment facilities containing organisms acclimated
   to the phenol concentration in the wastes.

•  pH and Alkalinity.  Due to the use of strong bases and acids in the
   unhairing and tanning processes respectively, wide pH variations and
   high alkalinities (from the beamhouse) can be expected in tannery
   waste.

   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.

   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
                                 64

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        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 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 eco-
        nomically advantageous to keep the pH close to 7.


     A comprehensive survey of wastewater generation  for  the entire industry

has been conducted in conjunction with the establishment  of effluent limita-

tions for the NPDES permit program  (USEPA 1979).  A summary of raw water data

for each subcategory of the industry is included in Table 6.  Additional data

are available in the Development Document for the industry  (USEPA 1979).


2.2.2  Priority Pollutant Generation  in Wastewater Streams


     Effective control of those pollutants  that represent the greatest danger

to aquatic ecosystems and to man is basic to environmental  protection.  The

most significant pollutants and pollutant parameters  detected in  the waste-

waters in terms of occurrence and concentration for the industry  in general
include:  the conventional and proposed conventional  pollutants BOD,., TSS, pH,

COD, and oil and grease; and the nonconventional pollutants, ammonia, total

Kjeldahl nitrogen  (TKN), and sulfide.  The  following  priority pollutants have

been found at more than two plants  and above the nominal  limits of detection

(USEPA 1979):


          2,4,5-trichlorophenol

          chloroform
          1,2-dichlorobenzene

          1,4-dichlorobenzene

          ethylbenzene
                                       65

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                               Table 6.   Raw waste  loads  by  subcategory.
Sjjbcategory
Pollutants — - —
Flow - (gal/lb)
BOD5
TSS
COD
Oil and Grease
Total Cr
Sulfide
TKN
Ammonia
Phenol
*c.anme>'t-ric mean o

_ 1
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
f collected d

2
5.5
983/45.1
1930/88.3
2610/120
244/11.2
31/1.4
20/0.92
137/6.3
90/4.15
2.2/0.1
ata» reporte*

3
4.0
1180/39.2
1680/56.1
5120/171
339/11.3
11/0.38
68/2.26
202/6.75
90/3.0
1.2/0.04
i as: (mg/1) /

4
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
(Ib./lOOO Ib.)

5
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
raw material

6
2.5
2460/51.3
3870/80.7
6400/133
556/11.6
104/2.16
118/2.46
460/9.6
120/2.5
1.5/0.03


7
18.9
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

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

SOURCE: U.S. Environmental Protection Agency.  1979.  Preliminary draft  development  document  for proposed
        effluent  limitations guidelines and new  source performance  standards  for  the leather  tanning  and
        finishing point  source  category.

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         methylene  chloride  (dichloromethane)
         naphthalene
         pe nt achlo r op henol
         phenol
         bis (2-ethylhexyl)  phthalate
         toluene
         chromium
         copper
         cyanide
          lead
         nickel
          zinc

     Of the 129 priority pollutants identified by USEPA, 46 have been identi-
fied in the raw wastewaters of the leather tanning and finishing industry.
The number of priority pollutants is higher when beamhouse operations using
the hair pulp process are present.

     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:

        syntans based  on naphthalene and phenol;
        4-nitrophenol  (a biocide,  as well as  a waterproofing agent);
        pentachlorophenol (a preservative and biocide);
        hexachloroethane, ethylbenzene and toluene solvents;
        2,4,6-trichlorophenol (a biocide);  and
        biocides  based on cresol.

The inorganic  toxic pollutants (including zinc, lead, nickel,  and  copper)
typically  originate in organometallic dyes.   Cyanide  also is  found in dyes,
and probably in  natural tannins as well.  The specific ingredients of the
chemical  formulations used in the tanning industry often are  not known by  the
 tanner,  particularly for compounds used in small quantities.   The  supplier
also may not have the exact formulation of these products or  may be unwilling
 to release this information.  Many of the tanning chemical solutions are

                                       67

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special formulations, prepared to serve a specific function rather than de-
veloped with consideration for the specific chemical activity of each ingre-

dient.


2.3  SOLID WASTE


     Solid wastes from the leather tanning industry may include both solid
materials (e.g., leather trimmings) and semi-liquid wastes that are most

commonly disposed on land (e.g., wastewater treatment sludges).  Reported

significant sources of solid waste include (SCS Engineers 1976):
     •  Leather wastes.  Pieces of leather in various stages of processing are
        routinely generated as the hide is trimmed for various tannery opera-
        tions.  Fine leather fibers also are generated in conjunction with
        buffing and shaving.  Leather wastes comprise about 35% of the industry
        solid wastes.

     •  Finishing wastes.  Residues from recycled solutions, usually in a
        slurry form, typically constitute about 2% of the industry solid
        wastes.

     •  Wastewater treatment solids.  Essentially all tanneries screen their
        wastewater and generate solid waste.  Many pretreatment facilities for
        tanneries generate sludge solids, as do all direct discharge systems.
        Waste treatment sludges constitute 60% of the process solid waste in
        the industry.

     •  Floor sweepings.  Included in this category are shipping materials
        (e.g., twine) and excess salt solids from cured hides.  This source
        represents about 3% of the process solid wastes from the industry.
     Additional solid waste generation estimates for the industry have been

summarized in Table 7.  These estimates include total process solid waste and

total hazardous (or potentially hazardous) solid wastes.  Information in the
table is also provided for tanneries not included in the effluent guidelines

subcategorization in Section 1.1.  Additional breakdowns of these data by
specific process are available in the literature (SCS Engineers 1976) and

could provide guidance for the applicant to use in estimating quantities of
solid wastes to be generated by a new tannery (USEPA 1979).
                                     68

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                                   Table  7.  Solid waste generation  estimates  for the leather
                                      tanning industry by effluent  guidelines subcategory.
lO
      Subcategory

1.  Hair pulp/chrome
    tan/retan-
    wet finish

3.  Hair save/non-chrome
    tan/retan-wet finish

4.  Retan-wet finish

6.  Unhair/chrome tan
    (through-the-blue)

*   Sheepskin tannery

*   Split tannery

*   Leather finishers
                                       1977 Solid Waste Estimate(l)
                                          Total        Hazardous(2)
(Dry)    (Wet)    (Dry)    (Wet)

 1,800   5,400   1,300   4,900



 2,700  12,000   None    None


 1,200   2,100     920   1,800

 2,600  10,200   2,400  10,000


   890   2,100     540   1,700

 4,300   8,900   4,000   8,600

   130     240      55     160
                                                                       1983 Solid Waste Estimate(l)
                                                                          Total        Hazardous(2)
(Dry)    (Wet)    (Dry)   (Wet)

 1,800   5,400   1,300   4,900



 2,800  13,000   None    None


 1,200   2,300     950   2,100

 2,600  10,200   2,400  10,000


   910   2,300     560   1,800

 4,300   8,900   4,100   8,700

   130     260      58     170
         *   Subcategory not designated for effluent guidelines.

         (1) All estimate as kg/1000 equivalent hide, where an equivalent hide weighs about 50 pounds.

         (2) Defined as hazardous or potentially hazardous.

         SOURCE:  SCS Engineers.  1976.  Assessment of industrial hazardous waste practices leather tanning and
                 finishing industry.

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     Hazardous compounds identified in sludges from tannery wastewater treat-

ment facilities are shown in Table 8 to include (SCS Engineers 1976):


     •  Chromium.  The chemistry of chromium is very complex, especially in
        untreated raw wastewaters where interferences from complexing mech-
        anisms 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 uncontrol-
        lable landfills.  Incineration, or similar destructive oxidation
        processes can produce hexavalent chromium, which in turn is poten-
        tially more toxic than trivalent chromium under certain circumstances.
        Studies on the effects of disposal of sludges containing trivalent
        chromium on agricultural land have produced conflicting conclusions.
        Some studies have not shown adverse effects, and in fact the nitrogen
        content of sludges have shown some beneficial effects.  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 potential for long-term
        accumulation and toxicity  in soils and plant tissue  (USEPA 1979).

     •  Copper.  This may leach from a  landfill into groundwater.

                    may leach  from a landfill  into  groundwater.
     •  Sulfides.  These may leach  from a  landfill  into  groundwater.  They may
        be converted to hydrogen sulfide in a  landfill,  as the pH is reduced
        by biological activity or mixing with  other waste streams.

     •  Phenols .  These may be leached from a  landfill into  groundwater.
        These compounds may be extremely persistent in the environment  and may
        be significant in trace amounts.


     Disposal of hazardous solid tannery waste has  the potential for creating

environmental problems if it is not properly handled.  The use of sludge
lagoons, landspreading, and landfilling techniques  require attention to proper

controls to assure that the leaching  of toxic  substances to  groundwater or

surface waters does not occur.  Spreading  tannery sludge on  the  land may  also
be a potential problem depending upon the  bacteria  present,  salt content,

presence of metals, and ultimate use  of the crop being grown on  the land

receiving the sludge.  Guidance on  issues  to consider in landspreading  of
sludge may be found in references such as  Application of Sludges and Waste-
waters to Agricultural Land;  A Planning and Educational Guide,  USEPA,  March

1978.
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              Table 8*  "Typical" tannery wastewater  treatment
                  plant sludge characteristics.*
Chrome leather tannery
                                                Chrome  leather   Vegetable leather
                 pretreatment/treatment  sludge   tannery sewer    tannery secondary
before
Constituent dewatering
Solids content 5-10
Chromium (mg/1) 3,000-6,000
Copper (mg/1) 100-150
Lead (mg/1) 10-25
Sulfides (mg/1) 20-50
Phenols (mg/1) <10
after sump sludge treatment sludge
HpwAtfirine (not dewatered) (not dewatered)
20-30 5-15
10,000-15,000 2,000-4,000
150-200 100-200
50-150 10-25
50-150 30-60
<10 <10
3-6
<5
<10
<5
25-50

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     If the RCRA regulations are promulgated as presently proposed,  most of
the industry's solid waste will have to be disposed of in USEPA approved
landfills in accordance with Subtitle C regulations.  These sites will have to
be designed and operated to satisfy all significant environmental concerns
regarding disposal of tannery waste.  However, consideration should  be given
to the other wastes to be disposed of to assure that waste interaction does
not create or cause leaching of any hazardous substance from the site.  (See
Section 3.3 for a discussion of sludge disposal alternative technologies).

2.4  OTHER IMPACTS

     The leather tanning industry can have significant impacts on public
health and the ecology of our environment if pollutants from the industry
processes are uncontrolled.  The industry can have other impacts that are not
directly generated by the tanning process.  In addition, the wastes from the
industry can affect  other pollution  control systems.  These potentials must be
addressed by the applicant.

2.4.1  Aesthetics
     New source leather tanneries are usually small,  enclosed complexes  that
should be designed to blend with the natural surroundings.  Although tanneries
do not normally require large tracts of land, waste treatment and disposal
needs for the tannery (e.g., a wastewater treatment plant or a solid waste
landfill) may require sizable tracts of land and may  detract considerably from
the surrounding landscape.  Also, due to the putrescible matter from the
fleshing and trimming processes, the existence of  the wastewater treatment
plant, and the sulfur used in the urihairing process,  odor from a leather
tannery may become highly objectionable.  Particularly  in rural and suburban
areas, leather tanneries along with their waste  treatment facilities can
represent a significant intrusion into  the environmental  landscape.  Measures
to minimize the impact on the environment must be  developed during site  selec-
tion  and tannery  planning design.  The  applicant should consider the following
factors  to reduce potential aesthetic impacts:
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     •  Existing Nature of the Area.  The topography and major land  uses
        in the area of the candidate sites are important.  Topographic  condi-
        tions and existing trees and vegetation visual barriers can  be  used  to
        screen the operation from view.  A lack of topographic relief and
        vegetation would require other means of minimizing impact, such as
        regrading or the planting of vegetation buffers.

     •  Proximity of Parks and Other Areas Where People Congregate for
        Recreation and Other Activities.  The location of public use areas
        should be mapped and presented in the BID.  Representative views  of
        the plant site from observation points should be described.  The
        visual effects on these recreational areas should be described  in the
        BID in order to develop the appropriate mitigative measures.

     •  Transportation System.  The visual impact of new access roads,  rail
        lines, haul roads, barge docking, pipelines, and storage facilities  on
        the landscape or waterfront should be considered.  Locations,  con-
        struction methods and materials, and maintenance should be  specified.


2.4.2  Noise


     The major sources of noise associated with the leather tanning  industry

include:


     •  fans and blowe rs;

     •  pumps and motors;

     •  mechanical unhairing equipment;

     •  splitting and trimming equipment;

     •  mechanical fleshing equipment;

     •  transfer trucks and equipment;

     •  compressors and sprayers;

     •  scrubbers and buffers; and
     •  wastewater treatment equipment  (e.g., air compressors).


     Various source and operational control methods are  available which can

effectively mitigate the undesirable noise impacts.   Such measures  include:


     •  enclosed process machines;

     •  mufflers on engines;
     •  sound barriers and isolation;

     •  vibration insulation; and

     •  acoustically  lined plenums.


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     The USEPA has recommended a. maximum 75 dBA,  8-hour exposure level to
protect workers from loss of hearing.   A maximum 55 dBA background exposure
level is also recommended to protect from annoyance during outdoor activity
(USEPA 1974d).  A suitable methodology to evaluate noise generated from a
proposed new source tannery would require the applicant to:

     •  Identify all noise-sensitive land uses and activities adjoining
        the proposed plant site (e.g., schools, parks, hospitals, and busi-
        nesses in the urban environment; homes and wildlife sanctuaries in the
        rural environment).
     •  Measure the existing ambient noise levels of the areas adjoining
        the site.
     •  Identify existing noise sources, such as traffic, aircraft fly-
        over, and other industry, in the general area.
     •  Determine whether there are any state or local noise regulations
        that apply to the site.
     •  Calculate the noise  level of the tannery processes, compare that
        value with the existing area noise levels and the applicable noise
        regulations.
     •  Assess the impact of the operation's noise and, if required, determine
        noise abatement measures to minimize the impact (e.g., quieter equipment,
        noise barriers, improved maintenance schedules).

2.4.3  Energy Supply

     The impact of a leather tanning facility on local energy supplies will
depend largely on the type of processes proposed and the ancillary facilities.
The applicant should evaluate the energy efficiencies of all processes con-
sidered during project planning and then consider the alternatives.  Feasible
design modifications also should be considered in order to reduce energy
consumption.

     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, re-
covery 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.

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     The removal or reduction of pollutants in any wastewater stream requires
an energy expenditure.  The higher levels of treatment produce a higher quality
effluent with lower levels of pollutants.  This means a greater energy con-
sumption than at lesser levels of performance.

     At a minimum, the applicant should provide the following information:

     •  Total external energy demand for operation of tannery.
     •  Total energy available on site.
     •  Energy demands by  type.
     •  Proposed measures  to reduce energy demand and increase plant
        efficiency.
     •  Proposed energy sources  and alternatives.

The New Source Tannery EID also  should  specifically address  the  topics in the
next sections.

     2.4.3.1  Energy  Consumption and Conservation

     Leather  tanning  facilities  are not large users  of  energy.   The  various
leather  tanning  processes  use  a  small  amount  of  energy, while the  facilities'
wastewater  treatment  plants  use  the majority  of  the  energy.   The focus  of
wastewater  treatment  and  control for  BAT level of performance is on 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 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 control technologies available to meet NSPS pro-
duce a higher quality effluent with lower levels of  pollutants. This means a
 greater energy consumption than at lesser levels of performance.  The increased
 energy requirements to meet the NSPS control requirements are projected to be
 small in absolute and relative terms (USEPA 1979).
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     2.4.3.2  Cogeneration

     The potential for cogeneration (e.g., using steam to generate electricity
on-site and for process requirements) should be evaluated in the BID.  However,
it is probable that the economic incentive for this technique will not exist
for most tanneries because of the relatively limited energy consumption for
the industry.  The applicant should investigate satisfying all or a portion of
the tannery energy needs using waste energy from nearby industrial facilities.

2.4.4  Socioeconomics

     Leather tanning facilities are usually small complexes but are often
associated with large cattle feedlots or meat packing plants.  The intro-
duction of a leather tanning facility into a community may cause land use,
economic, and social changes.  Therefore, it is necessary for an applicant to
understand the types of impacts or changes that may occur so that they can be
evaluated adequately.  The importance of these changes usually depends on the
size of the existing community where the facility is  located.  The trend now
is for leather tanning facilities to be located in more rural areas instead of
traditional urban areas.  The significance of the changes caused by a facility
of a given size normally will be greater near a small rural community than
near a large urban area.  This is due to the fact that a small rural community
is more likely to have a nonmanufacturing economic base and a lower per capita
income, fewer social groups, a more limited socioeconomic infrastructure, and
fewer leisure pursuits than a large urban area.  There are situations, however,
in which the changes in a small community may not be  significant and, con-
versely, in which they may be considerable in an urban area.  For example, a
small community may have had a manufacturing  (or natural resource) economic
base that has declined.  As a result, such a community may have a high Inci-
dence of unemployment  in a skilled labor force and a  surplus of housing.
Conversely, a rapidly  growing urban area may be severely strained to provide
the labor force and services required for a new leather tanning facility.

     The rate at which changes occur (regardless of the circumstances) also is
often an important determinant of the significance of the changes.  The appli-
cant should distinguish clearly between those changes occasioned by the construc-

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tion of the facility, and those resulting from its operation.  The former
changes could be substantial but usually are temporary; the latter may or may
not be substantial, but normally are more permanent in nature.  The potential
impacts which should be evaluated include:

     •  Increased land consumption and rate of land development.
     •  Land use pattern and compatibility changes.
     •  Economic base multiplier effects.
     •  Population size and composition  changes.
     •  Increased labor force  participation and  lower  unemployment rates.
     •  Increased vehicular traffic  and  congestion.
     •  Loss of prime agricultural  land  and environmentally  sensitive areas.
     •  Increased demand  for community  facilities  and  services.
     •  Increased demand  for water  supply,  sewage  treatment,  and  solid
        waste  disposal  facilities.

During  the construction phase, the  impact will be  greater if the  project
requires  large numbers  of construction workers to  be  brought in from outside
the community  than  if  local unemployed workers are available.  The potential
impacts include :

      •  Creation of  social tension.
      •  Short-term expansion of the local economy.
      •  Demand for increased police and fire protection, public utilities,
         medical facilities, recreation facilities, and other public services.
      •  Increased demand for housing on a short-term basis.
      •  Strained economic budget in the community where existing infra-
         structure becomes inadequate.
      •  Increased congestion  from construction traffic.

 Various methods of reducing the strain on the budget  of the  local community
 during the construction phase should be  explored.  For example, the company
 itself may build the housing  and recreation facilities and provide the utility
 services  and medical facilities for its  imported  construction  force; or the
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tannery may prepay taxes, and the community may agree to a corresponding
reduction in the property taxes paid later.  Alternatively, the community may
float a bond issue, taking advantage of its tax-exempt status, and the company
may agree to reimburse the community as payments of principal and interest
become due.

     During operation, the more extreme adverse changes of the construction
phase are likely to disappear.  Long-term changes may be profound, but less
extreme, because they evolve over a longer period of time and may be both
beneficial and adverse.

     The permit applicant should document fully in the EID the range of poten-
tial impacts that are expected and demonstrate how possible adverse changes
will be handled.  For example, an increased tax base generally is regarded as
a positive impact.  The revenue from it usually is adequate to support the
additional infrastructure required as the operating employees and their families
move into the community.  The spending and respending of the earnings of these
employees has a multiplier effect on the local economy, as do the interindustry
linkages created by the leather tanning facilities.  The linkages may be
backward (those of the facility's suppliers) or forward  (those of the faci-
lity's markets).

     Socially, the community may benefit as the increased tax base permits the
provision of more diverse services of a higher quality, and the variety of its
interests increases with growth in population.  Conversely, the transformation
of a small community into a larger community may be regarded as an adverse
change by some of the residents who chose to live in the community, as well as
by those who grew up there and stayed, because of its small town amenities.

     The applicant also should consider the economic repercussions if, for
example, the quality of the air and water declines as a result of wastes
generated by the leather tanning facility.  In some cases, traditional sectors
of economic activity may decline because labor is drawn away from them into
higher paying industrial jobs.  Also the tourist sector may decline if air and
water pollution is noticeable or if the landscape is degraded.
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     Thus, the applicant's framework for analyzing the socioeconomic  impacts
of the location of a leather tanning facility must be comprehensive.   Most  of
the changes described can and should be measured to assess fully the  potential
costs and benefits.  The applicant should distinguish clearly between the
short-term (construction) and long-term (operation) changes, although some
changes may be common to both (e.g., the provision of infrastructure).  The
significance of the changes depends not only on their absolute magnitude, but
on the rate at which they occur.  The applicant should also develop and main-
tain close coordination with state, regional, and  local planning and zoning
authorities to ensure full understanding of all existing and/or proposed land
use plans and other related regulations.

     USEPA's Office of Environmental Review is  developing a methodology  to be
used to  forecast  the socioeconomic  impacts of new  source  industries and  the
environmental residuals associated  with those impacts.  The manual describing
the method and its use is  expected  to  be  available in mid-1980.

2.4.5  Raw Materials Shipment  and Handling

     The leather  tanning  industry uses raw materials that may have adverse
environmental effects  due to improper handling  or accidents.   The  following
materials should  be  evaluated:

      •  hides  and skins,  describing their nature upon receipt (e.g.,  raw,
         brine  cured,  through-the-blue tanned);
      •  tanning  agents (e.g., chrome, vegetable, alum,  syntans);
      •  finishing materials;
      •  solvents;
      •  bleaching agents;
      •  dyes;
      •  pickling liquors; and
      •  other process chemicals.

      The significant factors for these materials  include storage, handling,
 and contingency  methods  to avoid adverse impacts  in  the event of an accident.

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     The hide raw materials sources especially should be characterized  by the
app1icant:

     •  Sheepskins are mainly imported, so the proximity of the tannery to
        port facilities should be indicated.
     •  Reliance on through-the-blue tanned leather as a raw material should
        be supported by the probable source (e.g., existing versus new tanneries)
     •  General availability of the tannery agent (e.g., chrome, alum,  or
        vegetable extract) might have a significant effect on product mix.
     •  Location and operation of brine curing facilities for the hide source
        should be addressed because of the putrescible nature of uncured hides
        and the associates difficulties with transport (e.g., odor at the new
        tannery, spoiled hides requiring disposal).
2.4.6  Site Preparation and Construction

     The environmental effects of site preparation and construction of new
leather  tanneries are common  to  land disturbing activities on construction
sites in general.  Erosion, dust, noise, vehicular traffic and emissions, and
some loss of wildlife habitats are  to  be expected and minimized through good
construction practices wherever  possible.   At  present, however, neither the
quantities of  the various pollutants resulting from  site  preparation and
construction nor their effects on the  integrity of aquatic and terrestrial
ecosystems have been studied  sufficiently  to permit  broad  generalizations.

     The major pollutant at a construction site is loosened  soil  that  finds
its way  into  the  adjacent water  bodies and becomes sediment.   Common remedial
measures include, but are not limited  to,  proper  planning at all  stages  of
development  ..nd application of modern  control  technology  to  minimize the
production  of  huge  loads  of sediment.  Specific control measures  include:

     •   the  use of  paved  channels  or pipelines to prevent surface erosion;
     •   staging or  phasing  of clearing,  grubbing,  and excavation  activities  to
         avoid periods  of  heavy rainfall;
     •   the use of  storage  ponds to serve  as  sediment  traps, where the over-
         flow may  be carefully controlled;  and
      •   the use of  mulch  or seeding immediately following disturbance.
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     If the applicant chooses to establish temporary or permanent  ground
cover, grasses normally are more valuable than shrubs or trees because  of
their extensive root systems that entrap soil.  Grasses may be seeded by
sodding, plugging, or sprigging.  During early growth, grasses should be
supplemented with mulches of wood chips, straw, and jute mats.  Wood  fiber
mulch has also been used as an antierosion technique.  The mulch,  prepared
commercially from waste wood products, is applied with water in a hydroseeder.

     The applicant must consider the capacity of the soils and geology  to
accommodate production and waste storage.  Problems which would require special
consideration  include:

     •  unstable  soils;
     •  steep  topography;
     •  presence  of  wetlands;
     •  location  relative  to  floodplains;
      •  permeability of  soils;  and
      •  erosion problems  during construction and operation.

      In addition  to the  impact  assessment framework provided  in the USEPA
 document,  Environmental  Impact  Assessment Guidelines for Selected New  Source
 Industries,  the permit applicant should tailor the conservation practices to
 the site  under consideration in order to account for and to protect site
 specific  features,  including:

      •  critical  habitats;
      •  archaeological/historical sites;
      •  high quality streams; and
      •  other sensitive areas on the site.

      The evaluation of site limitations should not be limited to the immediate
 vicinity of the project but should consider areawide restrictions, such as:

      •  proximity  to national  refuges, parks, and other pristine areas;
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     •  area water resource compatibility with industrial development;
     •  existing hazardous solid waste disposal facilities for the area;
     •  potential for developing solid waste disposal systems; and
     •  community attitudes and goals relative to industrial development.

These should be addressed with respect to the mitigative techniques available
to the applicant.  (See Section 4.0 for a detailed discussion of site selection
criteria).

2.4.7  Effects on Municipal Treatment Systems

     The usual alternative to treatment and discharge of treated wastewater
effluents is pretreatment for discharge to a municipal wastewater treatment
facility.  For the new source tannery, the effluent limits for both of these
alternatives are identical and equal to BAT limits.  When evaluating the
pretreatment alternative, the applicant should consider the following problems:

     •  large pieces of scrap hide and leather clogging or fouling operating
        equipment;
     •  excessive quantities of hair and other small-scale, screenable  solids;
     •  highly acidic or alkaline waste streams;
     •  wastewater flow surges;
     •  excessive loadings of suspended solids, settleable solids, and  BOD  ,
        consistently or in surges;
     •  odors, facilities corrosion, very high dissolved oxygen demand  in
        biological treatment system aeration basins, and hazardous gas  genera-
        tion from sulfide bearing wastes;
     •  a potential future problem with disposal of sludges containing  chrome;
        and
     •  pass through of ammonia nitrogen.

These factors also are significant for an industry operated waste treatment
facility.  The pretreatment standards for new  sources  (PSNS), if adopted as
proposed, will require pretreatment controls that are  adequate to alleviate
these problems.
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2.5  MODELING OF IMPACTS

     The ability to forecast environmental impacts accurately often is im-
proved by the use of mathematical modeling of the dispersion and dissipation
of air and water pollutants as well as the effects of storm runoff.  Two of
the most widely used and accepted models are:

     •  DOSAG (and  its modifications); and
     •  the QUAL series  of models developed by the Texas Water Development
        Board and modified by Water Resources Engineers, Inc.

These are steady-state,  one-dimensional  models useful in evaluating stream
impacts.  Some  of the  parameters  that these models simulate are:

     •  Dissolved oxygen.
     •  BOD,
     •  Temperature.
     •  pH.
      •   Solids.

 The data required for these models include (19761):

      DOSAG-I
      •  Flow rates for system inputs and withdrawals.
      •  Information on reaches, junctions, stretches, headwater reaches.
      •  Reaction coefficients.
      •  Concentrations  of inflows.
      •  Stream temperature.
      QUAL-II
      •  Identification  and  description  of stream reaches.
      •  Initial conditions.
      •  Hydraulic  coefficients  for  de.r-rmining  velocity and  depth.
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     •  Reaction coefficients.
     •  Headwater data.
     •  Waste loadings and runoff conditions.
     •  If temperature is to be modeled,  also  requires sky cover,  wet bulb/dry
        bulb air temperature, atmospheric pressure, wind speed,  evaporation
        coefficient, and basin elevation.
Other models are available for non-steady state conditions and two dimensions,
as required in modeling estuaries, including:

     •  RECEIV and RECEIV II, developed by Raytheon for the USEPA Water Planning
        Division.

These models can evaluate both conservative (e.g., dissolved solids, metals)
and non-conservative materials subject to first order reaction kinetics (e.g.,
BOD, DO).  The data required as input to both of these models include:

     •  Tidal variations.
     •  Water surface elevations, area, and depth.
     •  Bottom roughness coefficients.
     •  Meteorological data, including rainfall, evaporation, and wind velocity
        and direction.
     •  Downstream boundary conditions.
     •  Junction and channel data.
     •  Water temperature.
     •  Initial pollutant concentrations.
     •  Inflow data.
     •  Oxygen saturation and  reaeration coefficients.

     In addition, there  are many  available water quality models that  were
developed  in association with  NPDES  activity and the  need  for optimization  of
waste load  schemes  for an entire  river basin.

     There  are also available  mathematical models  that have been  used for air
pollution studies and solid waste management optimization.  A complete dis-
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cussion of available air quality modeling techniques is presented in
"Guideline on Air Quality Models," EPA-450/2-78-027  (USEPA 1978e).  Examples
of the application of these models include:

     •  For short-term dispersion modeling of point  sources, USEPA's PTMAX,
        PTDIS, and PTMTP models may be employed.
     •  For modeling of long-term concentrations over  larger areas, the L3EPA
        Climatological Dispersion Model may  be  used  for point and area sources.

Input data requirements for air quality modeling include  descriptions of the
meteorological setting, the existing  air  quality,  the  existing air pollutant
emissions, and the anticipated emissions  from the  new  source.  Pollutant
sources may include  (USEPA 1978e):

     •  Point sources.  Generally  considered a  major source  (e.g., greater
        than 50  tons/year) from a  stack or  group  of  stacks.
     •  Line sources.   Generally  confined to roadways  and streets with well-
        defined  motor vehicle movements.
     •  Area sources.   Typically  treated  as a grid network of  square areas
        with emissions  distributed uniformly within each grid  square.

     In general, the use  of  mathematical  models is indicated when arithmetic
calculations are too repetitious  or too  complex.   Their use also simplifies
analysis  of  systems  with intricate interaction variables.  Models thus  offer  a
convenient  way  of describing the  behavior of environmental systems.
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                            3.0  POLLUTION CONTROL

     New sources must attain discharge levels which are indicated as achiev-
able using technological options which meet the New Source Performance Standards
(NSPS).  They may be the technologies identified by USEPA in the development
of these standards or they may be alternatives which meet these standards by
other techniques.  For waste streams not specifically addressed by NSPS,
control applications which represent the state of the art should be described
in the BID.  The permit applicant must demonstrate that NSPS will be met.  The
sections which follow identify and describe typical Standards of Performance
and state of the art technologies with which NSPS can be met.

3.1  AIR - STANDARDS OF PERFORMANCE TECHNOLOGY

     Air emissions  from tanning and finishing operations are primarily  from
the following sources:  auxiliary boilers for in-plant heating, dust from the
buffing step of  the  finishing  operations, solvents  from the degreasing  or
finishing operations, and possibly  hydrogen  sulfide from the unhairing  pro-
cess.  Odor may  also cause air quality  problems,  due  to either  uncontrolled
sulfides or putrescible solid  waste materials.   In  addition, volatile organic
compounds may be released to the atmosphere  by  aeration systems in  biological
treatment.

3.1.1  Boiler Equipment

     Boiler  flue gas may  contain  several  air contaminants  controlled by PSD
and NAAQS  (e.g., total  suspended  particulates,  nitrogen oxides, sulfur  di-
oxide).   However, these are  low volume  sources,  so  that  oil  and gas-fired
units  usually require no  pollution  control measures to comply  with  guidelines.
If a  large  coal-fired boiler were proposed for the  tannery,  then wet  scrubbers
or electrostatic precipitators to remove  fly ash from the  stack gas might  be
required.   These units  are capable  of 98+% removal  of fly ash.

3.1.2    Buffing Dust Control

      The major potential  source of  particulate emissions from a tannery is
 from hide buffing operations.   Most tanneries control this by wet scrubbing of

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the buffing area exhaust.  Hide buffing particulates also are of concern due
to their chrome content.  The wet scrubbing operation transfers this waste
material either to the liquid or solid waste streams.  Buffing dust from the
wet scrubber is usually removed as a sludge for disposal with the other chrome
bearing tannery waste.

3.1.3  Hydrogen Sulfide Control

     Hydrogen sulfide is  the  other potential air  pollutant of consequence
originating from leather  tannery wastes.   A significant  portion of alkaline
sulfides contained in tannery wastewater  can be converted to hydrogen sulfide
at a pH below 9.0, resulting  in the  release of this  gas  to the atmosphere.
This gas is odorous, and  can  result  in property damage  through paint dis-
coloration.  In sewers, hydrogen  sulfide  can be oxidized to sulfuric acid,
causing "crown" corrosion and corrosion of equipment.   At higher  concentra-
tions this gas can 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.   Further,
careless mixing of acid  and sulfide  containing alkaline streams can also  be
catastrophic both  within  tanneries  and in sewers.

     The  sulfide  content  of tannery wastes must be reduced  and maintained at  a
 low level  for  other  treatment systems to work, to protect the health and  lives
of workers  exposed to  leather tanning waste waters, and to minimize the poten-
tial  for  air  pollution from any waste treatment system.  Because  of the over-
 riding  health  and safety considerations associated with hydrogen sulfide
control,  it  should never constitute a significant air pollution problem.
However,  a description of the facilities proposed for hydrogen sulfide control
 is necessary to assess adequately the potential health and safety impacts of
 the tannery.

 3.1.4   Ammonia

      A potential air pollution source is  the ammonia discharged into the air
 from specific treatment  equipment for ammonia removal.   Stripping the wastewater
 by any gaseous media would almost certainly produce an  ammonia vapor stream
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that would be discharged into the atmosphere.  Ammonia may be released as a
free gas from a wastewater stream containing ammonium hydroxide wherever the
pH is in a specific alkaline range.  Ammonia would be converted to nitrates
and nitrites in the presence of air and the proper bacteria in an extended air
or activated sludge type of treatment system.  Ammonia originates primarily
from the ammonium salts used in the bating step and may be stripped from high
pH wastes even without specially designed ammonia stripping facilities.  It is
necessary that all pollution control systems be addressed from the perspective
of pollutant transfer to other media.

3.1.5  Odor

     Odor can be associated with sulfide-bearing wastewater streams and with
decay of putrescible waste materials such as trimmings and fleshings.  The
control of these materials should be addressed in the EID.  The applicant
should specifically identify the control techniques proposed to minimize odor
generation from the tannery:

     •  Closed containers should be  available  for solid waste materials.
     •  Daily or more frequent removal of wastes should be indicated.
     •  Controls and detection instrumentation for hydrogen sulfide in  the
        plant atmosphere should be identified.

3.2  WATER -  STANDARDS OF PERFORMANCE TECHNOLOGY

3.2.1   In-Plant Controls

     Appraisals of plant waste production must first  investigate  the  manufacturing
cycle for any modifications  which  can reduce the waste flow and the concentration
of  waste constituents.  Particular emphasis rests on  reducing  those factors
which pose  problems in  treatment of  the  total  waste stream.   In  some  instances,
reuse or recovery  of materials from  process solutions  can produce economies
which will at  least partially  offset costs.

     Process  changes  and waste stream segregation are two methods of  pollutant
reduction and/or control essential to achieving the recommended  effluent
limitations,  wherever appropriate.

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      A number of  tanneries  are  considering  a  variety  of  process  change methods
 which could  result  in  reduced waste  loads,  increased  efficiency  in  use of
 chemicals, and reduction of  total water  use.   Tannery justification for  these
 process change methods depends  to some extent on  the  costs  of  installation and
 operation and the benefits  in whatever form for the particular tannery.  An
 important factor  in this decision is  the effect of any process change on the
 quality of the finished leather product  (USEPA 1979).

      The following  steps can often reduce pollutants  and  the costs  of waste
 treatment (USEPA  1979):

      Process Changes

      Process changes have been  difficult to make  in this  industry because of
 the diverse  tanning methods  employed.  While  tanning  operations  traditionally
 employed  the batch  system, it is possible that more of the  chemical  applica-
 tions as  well  as  the washing and rinsing could be handled more efficiently on
 a counter-current continuous flow basis.  This would  achieve maximum utiliza-
 tion  of  all  active  ingredients, leaving  only  concentrated wastes of  small
 volumes  for  treatment  and disposal.   Substitution of  effluents from  one  pro-
 cess  for  make-up  water  in another generally is feasible at  some points within
 a tannery.   Before  tanneries can make this  change however,  they must establish
 the quantity  of water  required  for each  operation.

      Substitution of Process Ingredients

      Several options exist for  the chemicals  used in tanning:

     •  Sulfides used  in  tanning can be  replaced with dimethylamine.
     •  Synthetic tanning agents (syntans) can reduce contamination normally
        associated with vegetable tanning.
     •  Unhairing can use enzymes to facilitate mechanical hair removal,
        improving the economic attractiveness of unhairing as  an alternative
        to the high pollutant generating hair pulping process.

The merits of  these substitution alternatives as well as similar opportunities
in other processes should be evaluated by the applicant.
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     Water Conservation and Reuse

     Water recycle and reuse should be maximized in a new tannery as the
initial step in the water pollution control effort.  Numerous techniques for
flow reduction have been demonstrated in tanneries throughout the world, but
the application of these techniques to a new tannery is dependent on the
process needs of the particular tanner.  The application of the following
water reuse and recycle techniques should be addressed for each new tannery.
Engineering, operation, and process modification aspects of water conservation
measures should be considered.

     •  Rinsing or washing hides in batches rather than using a continuous
        rinse system should be examined.  This holds potential for the most
        significant water savings of any process modification, since hides are
        rinsed after every major process step.
     •  Timers, preset meters, and other instrumentation (e.g., conductivity
        probes) should be considered for controlling rinse water volumes.
     •  Spent wash water and rinse water should be considered for process
        solution makeup.
     •  Non-contact cooling water  (e.g., vacuum driers) should be evaluated
        for recirculation potential.
     •  Process equipment alternatives  (e.g., hide processors, paddle vats,
        pumpable drums, float storage tanks) should be considered.
     •  Operation techniques and procedures should be developed to minimize
        wastewater  (e.g., flow restriction nozzles on washup hoses).

     Associated with a 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 of a water reduction  program in a  tannery
would be  a  vital  first step controlling wastewater volume, pollutant concen-
tration,  and/or pollutant  loading.

      Recovery and  Reuse  of  Process Chemicals

      The  most  efficient methods  for eliminating pollutants from tannery wastes
are the reuse  of  process  solutions and  the  recovery  of  materials normally

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wasted.  These both have been demonstrated effective for waste constituent

reduction, and the new tannery should consider the possibility of process

solution reuse, recycle, or recovery.  Alternatives which bear consideration

include:
     •  Reuse or recycle  of unhairing solutions.  This requires removal
        of solids from spent  solutions,  refortification with lime and shar-
        peners, and addition  of make-up  water.

     •  Reuse of chrome tanning solutions.  This can be performed either
        by settling, refortification, and reuse of  the solution as the prin-
        cipal tanning agent or by  reusing spent liquor for retanning.

     •  Reuse of vegetable tanning solutions.  The  Liritan process employs
        such a technique  by counter-current flow of tannage in relation to the
        hides.

     •  Reuse of retanning liquors or reuse of spent tanning liquors.

     •  Reuse of pickle liquors.   Spent  pickle liquors can be refortified for
        reuse and also can be used as makeup  for pickle liquor.

     •  Reduce lime used  in unhairing liquors.  Excess lime is commonly used
        for unhairing because it  is easier  to control  the process in  this
        manner.  Experiments  have  shown  that  the lime  required for effective
        unhairing is  less than  is  required  to saturate the protein (USEPA
        1979).

     •  Systems for recovery  of  sulfides from unhairing  liquor.  A pilot
        system has recovered  sulfide by  acidifying  the unhairing waste to
        produce hydrogen  sulfide  (H~S)  and  then  scrubbing  the H2S from the air
        stream with sodium hydroxide (NaOH)  to produce sodium sulfide which
        can be reused  (USEPA 1977b).

     •  Recovery of chrome from spent  tanning liquors.   This  is becoming more
        attractive as  the cost  of  trivalent chromium salts continues  to climb.
        A chrome recovery system can use lime precipitation of chrome as
        chromium hydroxide sludge, sludge dewatering,  and  acidification of the
        chrome hydroxide  cake with sulfuric acid  to produce an acidic chromium
        sulfate solution  (USEPA 1977a).

     •  Recovery of  system blowdown solutions.  System blowdown  is required  to
        prevent buildup  of contaminants in tanning, unhairing, washing, and
        other process streams where extensive recycling  is practiced. Vegetable
        tanners should consider concentrating tan  solution blowdown  for use  an
        a retanning  additive.
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     Stream Segregation for Separate Pretreatment

     Stream segregation is not an in-plant treatment technology,  per se.  It
is, in reality,  a critical installation or first step to implement most in-plant
technologies available to tanneries.  It is the physical separation or segrega-
tion of at least the two major wastewater streams in a tannery.   One stream
originates in the beamhouse, is highly alkaline and contains a substantial
organic load of  dissolved and suspended hair.  The 'other stream originates in
the tanyard, is  acidic, and has a chrome content of measurable level.

     These two major and substantially different wastewater streams can be
most effectively pretreated as separate streams rather than in a combined
state.  Constituent streams of these two major streams are the specific
process waste streams which may also respond better to separate treatment.
Effective segregation techniques that should be considered include the
following physical systems  (USEPA 1979):

     •  Processing equipment  (e.g., hide processors) can be connected by
        in-place piping to holding tanks for reuse or segregated discharge to
        treatment.
     •  Below grade sewers can be installed to serve process and rinse
        tanks with similar wastewater characteristics.
     •  Above grade sewers can be installed to serve process and rinse
        tanks.
     •  Curbs and dikes may be required to ensure wash waters are segregated.
        adequately.
     •  Flow diversion gates may be useful to segregate concentrated wastes
        in periodic dumps from low-concentration wastewaters.

     Control of Specific Waste Constituents

     The specific waste constituents associated with the industry may be
targeted for removal in-plant.  The waste constituents that could merit such
consideration include  (USEPA  1979):

     •  Lime 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

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to reduce the amount of lime to a minimum.  It is reported:  "Because
lime has a limited solubility, it is generally regarded as a safe
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.  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 be present in beamhouse liquors"  (USEPA 1979).

Chrome Reduction.  lanyard 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  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 dis-
posal 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%
(USEPA 1979).  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 (USEPA 1979).   After World  War II,
tanners went back  to  the older methods.  The  efficiency  of chrome use
is now  about  70%  (USEPA 1979).

Sulfide  Removal.   In situ sulfide oxidation in the drum  or paddle with
the hides has  been investigated and is in use.   TNO Institute investi-
gated  this  method  of  oxidizing sulfides in the lime liquors during  and
after  the  liming process (USEPA 1979).   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
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        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.

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


     Ammonia Reduction in the Bating Operation


     The major source of ammonia nitrogen and total Kjeldahl nitrogen (TKN) in

the tanning industry is from the bating or deliming operation.  Ammonium
sulfate or ammonium chloride are the two most frequently used deliming salts.

They can be used either alone or in combination with acid for deliming.  When
combined with acid, they create a buffer solution which is capable of neutral-

izing the residual lime in the hide without drastically reducing pH, which
would cause acid swelling.  Significant reductions in the concentration of

ammonia in wastewater effluents can be achieved by substituting other bating

salts or by using weaker deliming acids in place of the commonly used ammonium
salts.  Both magnesium sulfate and magnesium chloride have been substituted

successfully and their use should be given consideration as an in-plant pollu-

tion abatement measure (Koopman 1974).  Weak acids such as boric acid and
sodium bisulfate can be used to delime hides prior to tanning without the use

of a bating salt buffer solution.  These acids are effective and can avoid
swelling the hide, but they are not widely used because they increase pro-

cessing time.


     Recycle of Unhairing Liquor


     Results of small-scale trials on recycling of lime-sulfide unhairing

liquors have been reported in which the liquors have been recycled up to 27

times without deterioration in leather quality (USEPA 1979).  Different soak
methods were compared to determine which did not cause a build-up of salt in

the liquor that would affect the swelling and unhairing.  Matched-side trials

were conducted comparing:

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     1.  conventional unhairing and unhairing with lime recycle after solids
         removal;
     2.  conventional unhairing and unhairing with lime recycle and no solids
         removal; and
     3.  unhairing using  lime  recycle with solids and unhairing using lime
         recycle without  solids.

None of the trials produced  inferior quality leather.  Fats were found to
accumulate in recycled  lime  liquors when  the solids were not removed.  Ad-
vantages stated are the improved  effluent quality and the savings in water
use.  The work has been extended  to large-scale tannery trials.

     Enzyme Unhairing for Hair-Save Operations.

     Prerequisities for any  hair-saving method are:  it must unhair easily and
mechanically, with removal of  fine hair  (if possible without reliming); it
must be economical, not time-consuming; it must be suited to mechanized and
automated production processes; and it must give good leather quality.  Hair-
saving processes require  more  labor than  hair-burn processes, and tanners will
not incur additional costs unless there is a profit from the proceeds of the
hair and a cost savings in wastewater treatment.  Present trends in the in-
dustry are definitely toward the  hair-burn process.

          Summary of Industry  Efforts to  Implement In-Plant Controls

     Table 1 previously has  listed some feasible in-plant process change
methods and indicates the number  of tanneries which have considered and de-
cided 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 is successfully using magnesium sulfate in deliming with no
problem in leather quality and with a considerable reduction in nitrogen waste
load.
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     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 mainte-
nance .

     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 1 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 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.

     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 tech-
nologies 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.
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3.2.2  End-of-Plant-Controls

     The Federal Water Pollution Control Act, as amended by the 1977 Clean
Water Act, does not require the use of specific treatment technologies.
Instead, it leaves to the discretion of the individual tannery the selection
of control technologies to meet the New Source Performance Standards (NSPS)
for effluent control.  The selected technology may involve end-of-plant  controls
only or may involve a combination of in-process and end-of-plant controls.
The technologies described in this section have been identified as appropriate
to achieve NSPS effluent controls, but should not be interpreted as the  only
approved technology to meet NSPS  (USEPA 1979).  These descriptions should be
considered as generally applicable for the entire industry, except as indi-
cated .

     The New Source Peformance Standards  (NSPS) for each subcategory of  the
leather tanning industry were presented in Section 1.5, Table 4.  These pro-
posed NSPS include:

     •  Non-toxic, Non-conventional Pollutants.  These include total Kjeldahl
        nitrogen, ammonia, and sulfide.
     •  Toxic Pollutants.  These  include  phenol and chromium.
     •  Conventional Pollutants.  These include the conventional pollutants,
        BOD, COD, TSS, oil and grease.
     •  Indicator Pollutants.  These  include  BOD  , COD, TSS, oil and grease,
        TKN, ammonia, phenol, and chromium.

Control of toxic pollutants by controlling indicator pollutants has been
proposed by USEPA because it has  been  found  that control technologies that
remove  these materials also remove  toxic  compounds  (e.g.,  priority  pollutants)
that are present.  Because regulation  based  on specific analysis of all the
various priority pollutants identified  in tannery waste would place a severe
financial and administrative burden on the tanneries without a commensurate
benefit to the  environment, the  alternative  of selected  indicator pollutant
control was developed  (USEPA  1979).
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3.2.2.1  Preliminary Treatment


     The need for preliminary treatment or pretreatment is based on the

following factors:

     1.  Removal of pollutants found to pass through a POTW with inadequate
         treatment.

     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.

     5.  Sludge disposal criteria.

     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  particul?tes.   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 opera-
         tions.

      •  Equalization.  Equalization of waste streams is important in pretreat-
         ment facilities.   The volume and strength of waste liquors vary de-
         pending 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.

      »  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:  air oxidation; direct chemical
         oxidation; and catalytic  air oxidation.

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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 BOD  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 require-
ments in activated sludge aeration basins and secondary sludge pro-
duction and dewatering requirements.

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 BOD  .

Ammonia Nitrogen Reduction.  Ammonia  is difficult to remove from
tannery wastewaters.  Biological systems which remove BOD have not
been effective in removing ammonia.   For this level of treatment, EPA
considered several alternatives  for removing ammonia from deliming
wastes by physical-chemical treatment processes.  The ammonia intro-
duced into the tannery wastewater stream by the deliming process
ranges from 67 to 90% of  all the ammonia in the raw waste.  Thus,
substitution  for ammonia  or treatment of this ammonia containing
stream will greatly reduce the  final  ammonia content of the total
wastewater effluent.

These processes assure that the  primary ammonia containing stream is
segregated and the ammonia removed before it is combined with other
waste streams.  The segregated  ammonia  containing  stream has a higher
concentration of ammonia  than a  combined stream, and it is therefore
easier to treat by physical-chemical  methods.  The methods considered
were:

     1.  water evaporation followed by  crystallization or pre-
         cipitation of ammonium sulfate;

     2.  distillation of  ammonia;

     3.  precipitation of ammonia  as  calcium ammonium phosphate;

     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.
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3.2.2.2  Primary Treatment (Physical) Operations


     These operations are designed to remove suspended pollutants from the

wastewater stream, to reduce solids loadings to subsequent units, and also to

reduce organic loads.


     •  Plain Sedimentation.  Plain sedimentation is concerned with the
        removal of non-flocculating discrete particles and floatable low-
        density materials such as grease and scum.  Suspended solids reduc-
        tions can range from approximately 40 to 90%, with associated re-
        ductions in BOD5 from 30 to 60%.  Much of the suspended material
        removed is insoluble lime which produces a voluminous and heavy
        sludge.  Although grease removals are not indicated, high removals are
        expected with surface skimmers installed in clarifiers.  While high
        removals of suspended solids (90%) and BOD5 (60%) are reported,
        effluent concentrations are not reported below 130 mg/1  for suspended
        solids or 146 mg/1 for BOD   (USEPA 1979).  High chromium removals may
        result while sulfide concentrations are relatively unaffected.

     •  Chemical Coagulation and Sedimentation.  As an alternative to plain
        sedimentation, chemical addition prior to sedimentation has further
        increased the removal efficiencies of primary clarifiers.  Chemical
        coagulation results in higher removals of suspended solids, BOD  ,
        sulfides, chrome, and alkalinity through  flocculation of colloidal
        particles.  Alum, lime, iron salts, and polymers  have exhibited  satis-
        factory results.  Suspended  solids removals from  50 to above 98% and
        BOD   reductions of approximately 50 to 99% may be achieved  (USEPA
        1979).  The following removals have been  conservatively  established
        for coagulation-sedimentation of leather  tanning  wastewaters:  BOD  -
        60%;  TSS - 65%; COD - 60%; Oil and Grease - 70%;  Total Chromium  - 90%;
        TKN - 65%.


3.2.2.3   Secondary (Biological) Treatment


     Preliminary  treatment and primary treatment  do not remove all  of the

organic material  in a wastewater stream.  Most of the BOD,, and suspended
solids can be removed by  biological  processes which oxidize the  organic

materials.  Many  different  systems are known  for  the biological  oxidation of
wastewater.   In these systems bacterial respiration is the primary  method of

oxidizing organic substances present in the wastewater.   This  results  in a

substantial reduction of  the effluent BOD.  The higher level of  treatment

generally includes one  or more biological unit  processes  following  primary

treatment.   Secondary biological  treatment  technology  includes activated

sludge, various kinds of  lagoons,  and trickling  filters.   Selection of  one  of
these  biological  treatment  systems is influenced  by  factors  such as wastewater


                                     100

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constituents, effluent requirements, climatic conditions, site constraints,

operating characteristics, and economics.  It has been repeatedly observed in

tanneries and other industrial operations  that waste treatment systems achieve

the design effluent quality only if:   (1)  the design is correct for the waste-

water characteristics; (2) the system  is not overloaded,  (i.e., pollutant and

hydraulic loading not more than 100% of design specifications); and (3) all

components of the system receive regular and necessary maintenance.


     •  Trickling Filter Systems.  Trickling filter systems are used to
        treat tannery wastewater by very few tanneries (USEPA 1979).  Trick-
        ling filters have limited application in  the treatment of high strength
        tannery wastes.  System upsets are common due to  organic overload and
        climatic conditions.  Existing filters may be incorporated into systems
        for treatment prior to a second stage biological  system.

     •  Lagoons.  Lagoons, also referred to as oxidation  ponds or stabili-
        zation ponds, have been used for tannery  treatment where land is
        available as an economical alternative to activated sludge.  Lagoons
        provide equalization  and a desirable environment  for biological ac-
        tivity.  In lagoons with long  retention times, primary and secondary
        clarification may be  eliminated.   However, the efficiency of these
        systems is significantly reduced during cold weather and sludge
        accumulation will eventually make  it necessary to construct a new
        lagoon or dredge the  old one.  The three  types of lagoons available
        for the stabilization of organic wastes include:

        Aerobic Lagoons.  Biological stabilization in the presence of oxygen.
        These include lagoons that incorporate mechanical methods  (i.e.,
        stirring, spraying, or bubbling) to increase the  dissolved oxygen
        content in the lagoon.

        Anaerobic Lagoons.  Biological stabilization in  the absence of free
        oxygen.

        Aerobic/Anaerobic Lagoons.  A  stratified  lagoon  where aerobic activity
        predominates near the surface  and  anaerobic activity takes place near
        the bottom of the lagoon.

     •  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.  With proper
        design and operational control and use, high organic removals are
        possible.  Designs based on solids retention time (SRT) afford optimum
        residence time for solids with minimal hydraulic  retention.  However,
        pilot studies are recommended  to establish appropriate design para-
        meters defining the relative rate  of biological  growth and decay with
        a given wastewater.   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 of the excess sludge. Activated sludge is typically
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preceded by some form of primary treatment especially in tannery
applications.  Activated sludge systems, including various modifica-
tions, such as extended aeration, carousel, and oxidation ditch (Barber
1978) have been and can be effective in organic reductions to low BOD
concentrations.  Removals of suspended solids appear to be dependent
on the design and operation of the final clarifier.  During the program
for preparation of the Development Document, BOD removal from 89 to
98% and suspended solids removal from 90 to 98% were observed (USEPA
1979).

Rotating Biological Contactor.  The rotating biological contactor
(SBC) 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.   Rotating biological contactors could be used as a sub-
stitute for  an entire aerobic system.  The number of stages required
depends 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 BOD  reduction of 98%  is reportedly
achievable with  a four-stage RBC.

Nitrogen Control-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 sequen-
tially.  Process  controls  are critical  for nitrification to be suc-
cessful.  Dissolved oxygen should be  maintained above 1 to 2 mg/1  to
assure  consistent nitrification.  System pH  for domestic wastewater
has been shown critical, with pH 7.5  to  8.5  the optimum range.  Since
nitrification generates acidity  (excess  of hydrogen ions), a buffered
wastewater,  either naturally or  by  addition  of  alkaline chemicals,  is
required to  maintain  the optimum pH range.   Nitrification is extremely
temperature  sensitive,  with a minimum of 12  to  15° C required  for
effective  treatment.  Sulfides should be reduced to  less  than  1 mg/1
and  chrome reduced to 2 to 10 mg/1  to avoid  inhibitory  effects  on
nitrification.  Nutrients  are critical  as  for all  biological systems,
with phosphorus  normally required  for a tannery wastewater.

Nitrogen Control-Denitrif ication.   Denitrification,  the conversion
of nitrites  and  nitrates (primarily nitrates)  to  nitrogen is accom-
plished under much less stringent  conditions and  with  a larger  range
of organisms than nitrification.  The process  consists  of  biologically
reacting a carbon source (essentially fuel), such  as residual  organic
pollutants or methanol, glucose, methane,  or low nitrogen organic
waste,  with  the  nitrite-nitrate, oxidizing the  carbon  source  to C02 by


                            102

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        using the oxygen from the nitrite-nitrate, and liberating nitrogen
        gas.  Many denitrification processes are designed to use methanol  as
        the carbon source because of ease of process control, cost,  and water
        and bacteriological compatibility.

     •  Nitrogen Control-Summary.  Nitrification-denitrification has not
        been applied to tannery wastes on a full scale, but the technology has
        been applied to a variety of wastes.  Total nitrogen reduction can
        range from 30 to 90% with removal efficiencies extremely dependent on
        system operation.


3.2.2.4  Advanced Physical^Chemical Processes


     There are several technologies available for the new source tannery that

the applicant might consider.  These are not used by the industry at this

time, but they could be effective in meeting NSPS.


     •  Combined Primary and Secondary Treatment.  Physical-chemical processes
        have been proposed for treating wastewater streams where all pollutant
        components can be flocculated and removed by sedimentation.  Such a
        system for the leather tanning industry has been patented by Chappel
        (USEPA 1979) using an acidic solution (mineral acid, aluminum sulfate,
        and oxidizing chemicals) and an alkaline  solution  (sodium hydroxide,
        dissolved aluminum, and oxidizing chemicals).  Separate  treatment with
        these solutions is given to  two segregated wastewater streams from the
        tannery, after which these are combined.  Flocculation and pollutant
        removal is reported for both separate treatment and  after combining
        the streams.  Sludge is recirculated to aid in flocculation.  When
        this system was used on a retan facility  wastewater, removal effi-
        ciencies were reported at 99+% for  BOD, 95+% for TKN and ammonia, and
        99+% for chrome.  When the process  was tested on other tanneries, it
        was found similarly effective for BOD, chrome, and  sulfides.

     •  Powdered Carbon Addition to  Activated Sludge.  This  process involves
        metering activated carbon into the  activated sludge  facility influent.
        The process effectiveness relies  on the processes complementing each
        other and thereby  improving  overall treatment  effectiveness.  Improve-
        ments reported include:

        -  improved organic pollutant  removals, including BOD,  COD, and  TOC;

        -  more uniform operation and effluent quality, particularly during
           periods of widely varying  organic and hydraulic  loads;

        -  decreased effluent solids  and thicker sludges resulting in reduced
           sludge handling  costs;

        -  adsorption of  organics, such as detergents,  oils,  and  dyes,  that
           are refractory  to the  biological  system;


                                      103

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- protection of the biological system from toxic waste components;

- more effective removal of phosphorus and nitrogen; and

- increased effective plant capacity at little or no additional
  capital investment.

A major inhibition to the widespread use of granular activated carbon
has been the high capital cost of installing thermal regeneration
facilities in small installations.  A possible solution to this problem
has been developed by a major chemical company whereby customers can
lease carbon adsorption systems at a guaranteed monthly charge.  The
company assumes the responsiblity for regeneration at central facilities.

Multi-media Filtration.  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 phosphorus
removal from secondary effluents, and in physical-chemical systems for
the treatment of raw wastewater.  Waste containing suspended solids is
passed through the filter containing granular material resulting in
the capture of suspended solids in the bed.  Eventually, the pressure
drop through the bed becomes excessive or the ability of the bed to
remove suspended solids is impaired.  The filtration cycle is terminated
and the bed is backwashed prior to being placed back into service.  In
an ideal filter, the size of the particles should decrease uniformly
in the direction of flow.  This condition is partially achieved with
the use of a multimedia deep bed filter.  This type of filter utilizes
materials with different densities ranging from the large size par-
ticles at the top of the filter having the lowest density and the
smallest particles at the bottom of the filter having the highest
density.  With this arrangement, the filter has a large storage capa-
city for suspended solids, and is able to remain in operation for
longer periods of time.  Influent solids should be limited to about
100 mg/1 to avoid too frequent backwashing.  Effluent suspended solids
are normally less than 10 mg/1.  The following conservative long-term
performance is reasonable after application to PAC upgraded activated
sludge effluent:  BOD  - 14 mg/1; TSS - 16 mg/1; Oil and Grease - 6
mg/1; COD - 40 mg/1; Total Chromium - 0.25 mg/1; TKN - 15 mg/1.

Electrodialysis.  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.

Whenever an effluent stream contains an organic or inorganic ionic
material, electrodialysis offers a possible method for recovery,
separation, segregation, or concentration of that material, provided
adequate pretreatment requirements are consistently achieved.  Of
paramount importance, of course, is the avoidance of membrane fouling,
either by scaling or suspended solids, when considered for tannery
applications.  Other conditions such as pH fluctuations and dissolved
                              104

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       organic solids concentrations also must be  carefully controlled if
       electrodialysis is  used  in the tannery.  Yet,  with water recovery
       rates of 80-90%,  greatly reduced  disposal volumes, the independence of
       chemical additives  and  low energy requirements, electrodialysis
       streams may be an economically feasible means  of meeting the parallel
       challenge of wastewater  treatment and  recovery through brine concentra-
       tions .

    •  Nitrogen Removal.   While biological  removal methods are effective
       for control of ammonia  in wastewater effluents, various physical-chemical
       methods are also  available.   In  general,  the following systems might
       be effective for  treatment of a  segregated, ammonia-bearing wastewater
       from  the deliming process:


       - Use of alternative deliming agents,  such  as epsom salts.

       - Evaporation  of  water  followed  by  crystallization or  precipitation  of
         ammonium sulfate.

       - Distillation of ammonia.

       - Precipitation of  ammonia  as calcium ammonium phosphate.

       - Precipitation of  ammonium sulfate by addition of ethanol.

       - Reverse  osmosis.

       - Ion exchange.


       The  use  of  alternative  deliming agents is now being  investigated in
       the  industry.   None of  the  other technologies are now used in a tannery
       for  treating  ammonia wastes, but these technologies  are used  in other
       industries  or  should work because of known chemical  principals.

     , Protein  Precipitation.   The beamhouse waste stream can be successfully
       treated  to reduce COD,  BOD, nitrogen, dissolved solids, and suspended
       solids  contributed  by the unhairing process.  Proposed technologies
       include  plain and chemical coagulation, sedimentation, flue gas car-
       bonation,  screening, filtration, and centrifugation.  The effective-
       ness of  this  technique on the total waste  stream varies.  The removed
       materials are largely proteinaceous matter, and can be used as feed
        for  chickens  when supplemented with key amino acids.

               Summary of Waste Control  and Treatment Technology


     The  preceding discussion addresses  numerous technologies which can
be employed in-plant or  end-of-pipe  to minimize the  quantity of pollutants
discharged by tanneries  to  POTW's or surface  waters.  These technologies are

pertinent to the leather tanning industry because  they  (1) reflect current


                                      105

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        Fismre  7.  Technology  schematic  for in-plant  control and preliminary treatment for the hair pulp/
             chrome  tan/retan-wet  finish and hair save/chrome tan/retan-wet finish subcategories.

BEAM HOUSE
                                                                                CARBON AT ION/
                                                                               SEDIMENTATION
                                         AMMONIA
                                       SUBSTITUTION
                 CHROME
                 TANNING
                 STREAM
                                                                                                         COMBINED
                                                                                                         WASTE
                                                                                                         STREAMS
                                                                                                         TOEND-OF-PIPE
                                                                                                         TREATMENT
    Source:
   1979   Preliminary draft development document for proposed
new source performance standards for the leather tanning and
             finishing industry.

-------
                     Figure 8.  Technology schematic for in-plant control and preliminary treatment
                          for the hair save/non-chrome tan/retan-wet finish subcategory.
BEAM HOUSE
            ALKALINE
            UNHAIRING
            STREAM
 SULFIOE
RECOVERY/
  REUSE
   FLUE GAS
 CARBONATION/
SEDIMENTATION
 TAN YARD
                  OELIME
                  STREAM
                                                                           COMBINED
                                                                           WASTE
                                                                           STREAMS
                                                                                                        TOEND-OF-PIPE
                                                                                                        TREATMENT
                                           LEVEL I
                                                                     LEVEL
       Source:  U.S. Environmental Protection Agency.  1979.  Preliminary draft development document  for proposed
                effluent limitations guidelines and new source performance standards for the leather  tanning and

                finishing industry.

-------
                  Figure 9.  Technology schematic for  In-plant control for the retan-wet finish subcategory.
    BEAM HOUSE
                                      NO BEAM HOUSE WASTE STREAM
     TAN YARD
o
oo
RETAN-
WET FINISH
STREAM


SCREENS-
ftOIT
REMOVAL


TO ENO-OF-PIPE
TREATMENT
                                                                LEVEL 2
      Source:  U.S.  Environmental Protection Agency.  1979.   Preliminary draft development document  for  proposed

               effluent  limitations guidelines and new source performance standards for the leather  tanning and

               finishing industry.

-------
Figure 10.  Technology schematic  for  in-plant control for the no beamhouse and shearling subcategories.
 BEAM HOUSE
                              NO BEAM MOUSE WASTE STREAM
  TAN YARD

CHROME
TANNING
STREAM



CHROME
REUSE

>


SCREENS-
GRIT
REMOVAL


TO END-OF-PIPE
TREATMENT
                                                LEVEL I
                                                                        LtVEL Z
Source:
U.S. Environmental  Protection Agency.  1979-  Preliminary draft development  document  for
effluent limitations  guidelines and new source performance standards for the leather  tanning and
finishing industry.

-------
  Figure 11.  Technology schematic for in-plant control and preliminary treatment for the through-the-blue subcategory.
BEAM HOUSE
                                                                               FLUE GAS
                                                                              CAftBONATION/
                                                                             SEDIMENTATION
TAN YARD
                                  COMBINED
                                  WASTE
                                  STREAMS
                                                                                                      TO ENO-OF-PIPE
                                                                                                      TREATMENT
                                         LEVEL I
LEVEL  2
       Source;  U.S.  Environmental  Protection Agency.  1979.  Preliminary draft development  document  for proposed
                effluent limitations  guidelines and new source performance standards for the leather  tanning and
                finishing industry.

-------
             Figure 12.  Technology schematic for end-of-p±pe wastewater  treatment.

^
J





LEVELS \&Z
COMBINED
WASTE
STREAMS
EQUALIZATION
AND
COAGULATION-
SEDIMENTATION


f'MYSICAL-
CHEMICAL
1 KLAI MtNT
/OMPPELt
VPROCESS;



1
LEVEL 4A 1

f

1 1 Tu
RECEIVING
WAI
i


EXTENDED
AERATION
ACTIVATED
SLUDGE
V

ACTIVATED
SLUDGE
WITH
PAC
ADDITION
>-

MULTI-
MEDIA
FILTRATION


GRANULAR
ACTIVATED
CARBON
COLUMNS


ERS

      LEVEL
LEVEL 4
                                                  LEVEL 5
                                             LEVEL 6
LEVEL 7
Source:   U.S. Environmental Protection Agency.   1979.   Preliminary draft development document for proposed
         effluent limitations guidelines and new source performance standards for the leather tanning and
         finishing industry.

-------
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 up-
grading of secondary biological treatment with PAG addition.  To control toxic
organic compounds and heavy metals, EPA assessed this technology from infor-
mation developed by the organic chemicals and petroleum refining industries
and then applied to leather tanning effluents.

     Applicable technologies for the leather tanning industry and their per-
formance were determined upon the best available information.  As can be seen
from Figures 7 through 11, 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 equaliza-
tion followed by coagulation-sedimentation  (Level 3).  A schematic of the
appropriate end-of-pipe treatment technologies,  including Level 3,  is pro-
vided in Figure 12.

3.2.3  Toxic  Pollutants

     The effectiveness of the treatment processes described previously has
been investigated for toxic pollutants (USEPA 1979).  The conclusions relating
to the removal of these materials are (USEPA 1979):

     •  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.  It also appears that this occurs regard-
        less of treatment effectiveness on any other pollutant parameters
        whether standard or priority.
     •  Semivolatile organics also receive a significant degree of removal
        by all waste treatment systems in use.  Those systems that are most
        effective in removing the standard pollutants (COD, BOD5, TSS, Oil and
        Grease) also seem to be most effective on semivolatiles.
                                    112

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     •  Metals comprise the inorganic groups 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 standard pollutants.  The most effective treatment system
        on metals is the physical-chemical system.
     •  The fate of the toxic pollutants is not certain.  It is highly
        probable that a substantial percentage of the pollutants are removed
        with the solids separated from the wastewater.
     •  Toxic pollutant removal effectiveness in general correlates with
        standard pollutant removal.

     The Pretreatment Standards for New Sources (PSNS) have been proposed  as
equivalent to NSPS due to the control requirements for priority pollutants
(USEPA 1979).  Therefore, the technologies previously described would also be
considered as appropriate for new leather tannery and finishing facilities
that propose discharge to a publicly owned treatment works.

3.3  SOLID WASTE - STANDARDS OF PERFORMANCE TECHNOLOGY

     As described in Section 2.3, solid waste from a tannery with a wastewater
pre treatment/treatment system may include any or all of the following:

        Fleshings.
        Hair.
        Hide trimmings.
        Tanned hide trim and shavings.
        Leather trimmings.
        Buffing dust.
        Leather finishing residues.
        Wastewater treatment sludges.
        General plant waste.

The specific types of solid waste generated by a tannery depend upon the type
of processing operations conducted, and the quantity of each type of waste
generated depends upon the volume of production at the  tannery.

     In view of the hazardous nature of much of the tanning industry's wastes,
there is reason for concern over concentrating priority pollutants removed
from the other plant waste streams  in the plant's solid waste.  The fate of
the priority pollutants  as they are removed from tannery waste  is unknown at
this time.  Currently, the predominant assumption is that a significant pro-
                                  113

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portion of these pollutants remains intact in the solids that are removed from
the wastewater.  These solids are subsequently disposed in landfills and dumps
with varying levels of control (SCS Engineers 1976).  Identification of four
tannery processes as hazardous waste sources under the proposed RCRA regula-
tions (Section 1.5) may help reduce the uncertainty concerning the fate of
some priority pollutants, but the entire solid waste stream for a new tannery
should be thoroughly evaluated.

3.3.1  Reduction of Hazardous Waste Components

     The primary contaminants of solid tannery wastes are chromium, zinc,
lead, and copper, with smaller but unknown quantities of organic and inorganic
priority pollutants also present.  In-plant process modifications to eliminate
the use of as many of the priority pollutants as possible at their source
would obviously  reduce their concentration in solid tannery residuals.  Reuse
and/or recovery  of waste streams containing chrome, dyes, or other toxic
pollutants not only reduces  the  contamination of solid  waste residuals  but
makes more efficient  use of  materials  which, as  in the  case of  chrome,  are
becoming  increasingly more expensive.   Some metals are  introduced  into  the
waste stream as  corrosion products  from tannery  equipment.  Alternative con-
struction materials should be  considered  as  a possible  means of reducing  the
introduction of  metals from  this source.

     When the  treatment  of segregated  waste  streams produces a solid waste,
the specific contaminants  in the solids  are  generally known and these  con-
taminants are  in their most  concentrated  form.   Solid wastes  in this  form are
most manageable  in terms of  control  and  appropriate disposal.   Taken  in general
perspective, numerous small  quantities of solid  waste of  more  concentrated
composition are  generally  more economical to handle and transport,  and are
much more environmentally  manageable than a  single, large, dilute,  and multi-
contaminated  solid waste from a POTW.

3.3.2   Solid  Waste Utilization

      Tanneries which generate fleshings and hide trimmings may be able to sell
these  waste materials to rendering plants, or occasionally to glue manufac-
                                      114

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turers.  Since these waste materials are highly putrescible, daily collection
is required.  Most vegetable leather tanneries and a few chrome leather tan-
neries remove hair from hides using a hair save operation.  If a market is
available, the hair can be washed, dried, and baled, and subsequently sold as
a by-product.  Since few markets  exist, however, most hair is simply disposed
of in a landfill.

     Some chrome  leather tanneries which  generate  large quantities of tanned
hide trimmings and shavings, particularly split leather tanners located in the
northeastern United States, are able  to sell this  waste material as a by-product.
By-product uses include manufacture  of  fertilizer,  chrome glue, hog feed
supplement, or leather board.   The majority  of  this  type of waste, however, is
disposed as solid waste.

     Four alternative  uses  for scrap  leather examined  in a  report  for  the
Tanners Council of America  (1977) and summarized  in the effluent guidelines
development document  (USEPA 1979) were:

     i •  Incineration of  blue  split and finished leather waste.
      •  Fiberized leather  for  loose building insulation.
      •  Pyrolyzed leather waste to make activated carbon  and  by-product
        chemicals.
      •  Hydrolyzed  leather and cattle hair to make leather and hair meals
        for  use  in  animal  and  pet foods.

Possible  economic incentives  exist for each of these alternative  uses.  However,
their actual  application has been limited to date.  Such alternatives  could be
economically viable for new plants.  More information on these alternative
uses may  be found in USEPA's Development Document (USEPA 1979).

 3.3.3  Solid Waste Treatment

      Approximately 60% of the  solid waste generated by the leather tanning and
 finishing industry is wastewater treatment residue  (SCS Engineers 1976).
 Therefore, a major part of tannery waste treatment  involves the handling and
 disposal  of the  semi-solid sludges obtained  from  liquid treatment processes.
                                     115

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Primary and/or secondary treatment sludge from chrome tanneries normally is
dewatered prior to disposal.   Sludge dewatering may be accomplished by:

     •  Gravity dewatering (sequential settling).   This is relatively un-
        common, but sludge drying beds on the tannery plant site may be
        successful where rainfall is less than evaporation.
     •  Mechanical sludge dewatering.  Normally this is accomplished using
        vacuum filters,  centrifuges, or filter presses, which have all been
        found to be effective in producing sludge cakes ranging from 10 to 40%
        solids.
     •  Evaporative lagoons.   Secondary wastewater treatment sludges from
        vegetable tanneries are normally dewatered in this manner, after which
        the sludge is used as a soil conditioner or disposed of in a dump or
        landfill.
Conditioning or stabilization of waste treatment plant sludge using heat
treatment provides a stable end product, but may have adverse effects on the
chemical quality of the sludge.  In testing a heat-treated alkaline sludge, it
has been indicated that some of the trivalent chromium may be oxidized to the
more soluble and toxic hexavalent form.  Apparently, the trivalent chromium is
converted through the high temperature, high pressure, high pH, and the oxi-
dizing environment of the heat treatment process (USEPA 1979).

3.3.4  Solid Waste Disposal

     The predominant methods of ultimate disposal of tannery waste include
sludge lagoons, landfills, dumps, trenches, and land spreading.  Some of these
facilities are not entirely adequate as disposal sites for hazardous wastes
since they do not provide adequate isolation of the hazardous substances from
the human environment.  Their use will no doubt be eliminated once RCRA regu-
lations regarding hazardous tannery wastes are promulgated.  The factors that
should be considered during solid waste disposal evaluations include:

     •  Sludge lagoons, dumps, landfills, and land spreading areas present the
        potential for leaching of toxic materials into the groundwater table.
     •  Incineration, pyrolysis, wet oxidation, or similar high temperature
        and pressure sludge destruction processes can generate hexavalent
        chromium, which is more soluble than trivalent chromium in the acid
        range of pH generally found in landfills.
                                       116

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     •  Acetic acid produced by the anaerobic decay of garbage in landfills
        can solubilize trivalent chrome, increasing its susceptibility for
        leaching, and can contribute to oxidation of trivalent chrome to
        hexavalent chrome.
     •  Leather finishing residues may contain significant quantities of
        flammable organic solvents, indicating that disposal sites which
        receive this type of waste need to  take precautions to minimize the
        potential fire hazard  from this material.  The quantities of this type
        of waste which are  generated are small enough that land disposal is
        thought to be an environmentally adequate disposal alternative.

A hazardous waste disposal  site must be carefully selected to minimize surface
water flow across the site, and the predominant soil types should be able to
contribute to leachate attenuation.  Operational procedures should be employed
which will minimize percolation of precipitation through  the refuse.  Leachate
collection systems at landfills used for hazardous  solid  waste disposal are
recommended to include impermeable barriers as a minimum  to provide adequate
assurance that ground and surface waters will be protected from contamination.
Monitoring wells around  the site also  are  recommended to  detect any break-
through or leachate before  it  spreads  to other areas.

     Tannery wastes such as vegetable  tannery  sludge, general plant waste
(strings, paper, boxes), and  uncontaminated scraps  or hair may be nonhazardous
and therefore amenable to disposal  in  a regular  landfill. This would  require
segregation from the  potentially  hazardous wastes.   Since these potentially
nonhazardous wastes make up a relatively  small portion  of the  industry's  total
solid waste production,  it  may not  be  economical  to dispose  of  them separately.
                                      117

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                   4.0  EVALUATION OF AVAILABLE ALTERNATIVES

     The alternatives section of the BID should address each reasonable alter-
native available for the new source leather tanning and finishing facility.
The purpose of this analysis is to identify and evaluate alternate plans and
actions that may accomplish the desired goals of the project.  These alterna-
tives can include process modifications, site relocations, project phasing, or
project cancellation.

     For the alternatives to a. proposed project to be identified and evaluated
properly, the impact assessment process should commence early in the planning
phase.  In this manner, social, economic, and environmental factors against
which each alternative is to be judged can be established.  Cost/benefit
analysis should not be the only means whereby alternatives are compared.  The
environmental and social benefits of each alternative also must be considered.
In general, the complexity of the alternative analyses should be a function of
the magnitude and significance of the expected impacts of the proposed pro-
cessing operations.  A small tannery that uses purchased  raw materials or
existing by-products may have a relatively minimal impact on a region and
generally would require fewer alternatives to be presented in the EID.

     The public's attitude toward the proposed operation  and its alternatives
also should be evaluated carefully.  In this way key factors such as aes-
thetics, community values, and land use can be assessed properly.

4.1  SITE ALTERNATIVES

     New leather tanning facilities are usually located on the basis of  the
following:

     •  convenience  to hide sources;
     •  an adequate  labor force and water supply;
     •  proximity  to energy supplies and transportation;  and
     •  minimization of environmental problems.
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Preliminary site selection activities normally take place before the EID
document is prepared.  The potential impacts that a new leather tanning
facility may have on the alternative site areas should be evaluated as to
their significance; magnitude; frequency of occurrence; cumulative effects;
reversibility; secondary or induced effects; and duration.  The identification
and analysis of the alternative site areas should be described in the EID and
the reasons for eliminating a site(s) should be specified.  The EID discussion
should particularly emphasize the environmental considerations given during
the site selection process.  This should particularly identify the existence
of sensitive areas, environmental constraints at each considered site (e.g.,
effluent receiving stream conditions, air quality, water and groundwater con-
ditions), and the significance of these constraints with respect to the specific
facility.  Consultation with the appropriate resource agencies during the
early stages of site selection is recommended.  Key agencies that can provide
valuable technical assistance include:

     •  State, Regional, County, or Local Zoning or Planning Commissions.
        These sources  can describe land use programs and determine if vari-
        ances would be required.  Federal lands are under the authority of the
        appropriate Federal  land management agency  (Bureau of Reclamation,
        U.S. Forest Service, National  Park Service, etc.).
     •  State or Regional Water Resource Agencies.  These sources  can pro-
        vide information relative to water appropriations and water  rights.
     •  Air Pollution  Control Agencies.  These  sources  can provide assistance
        relative to air quality allotments and  other air-related  standards and
        regulations.
     «  The Soil Conservation Service  and State Geological Surveys.  These
        sources can provide  data and consultation on soil conditions and
        geologic characteristics.

Further consideration  should be given  to  any  state  siting laws.   The appli-
cable regulations  should be  cited and  any applicable constraints  described.

     The EID  should  include  the potential  site locations  on  maps,  charts, or
diagrams that show the relevant site  information.   (A  consistent  identifica-
tion system for  the  alternative  sites  should  be established  and retained  on
all  graphic and  text material.)   They  should  display  pertinent  information
that includes, but is  not  limited  to:

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     •  areas and sites  considered by the applicant;
     •  major centers of population density (urban, high,  medium,  low density,
        or similar scale);
     •  water bodies suitable for cooling water or effluent  disposal;
     •  railways, highways  (existing and planned), and waterways suitable
        for the transportation of materials;
     •  important topographic features (such as mountains  and marshes);
     •  dedicated land use  areas (parks, historic sites,  wilderness areas,
        testing grounds, airports, etc.); and
     •  other sensitive environmental areas.

Using the foregoing graphic materials, the applicant  should provide a con-
densed description of the major considerations that led to the selection of
the final candidate areas,  including:

     •  proximity to markets and raw materials;
     •  economic analyses with  trade-offs;
     •  adequacy of  transportation systems;
     •  environmental aspects,  including the  likelihood of floods;
     •  license  or permit problems;
     •  compatibility with existing  land use  planning programs; and
     •  current  attitudes of interested citizens.

     The BID should  indicate the  steps, factors,  and  criteria used to select
the  proposed site.   Quantification,  although  desirable, may not be possible
for  all factors  because of lack of adequate data.  Under  such circumstances,
qualitative  and  general comparative  statements,  supported by documentation,
may  be used.  Where possible, experience  derived from operation of other
plants at  the same  site, or  at  an environmentally similar site, may be  helpful
in appraising the  nature of  expected environmental impacts.
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     Economic estimates should be based at least on a preliminary  conceptual

design that considers how construction costs are affected by such  site  related

factors as:


     •  topography;

     •  geology;

     •  tectonics; and

     •  meteorology.


     A. specific site  for  location of  the  leather tanning facility  may be

unacceptable and require  abandonment  for  a number of reasons.  This could

include:


     •  Impact on  a unique,  recreational, archaeological, or other important
        natural resource  area.   Reviews are  mandated in  the permitting process
        by several public agencies  relative  to  these factors, including the
        Soil Conservation Service,  Fish and  Wildlife Department, State Historic
        Preservation  Officer,  and others.

     •  Destruction of  the rural or pristine character of an area.

     •  Conflict  with the planned development for  the area.

     •  Opposition by citizens groups.

     •  Meteorological and climatological aspects.

     •  Periodic  flooding, hurricanes,  earthquakes, or
        other  natural disasters.


 4.2 ALTERNATIVE  PROCESSES AND DESIGNS


     The  following presents a methodological approach to the analysis  of

 process and  design alternatives.  The discussion of specific system alter-

 natives is presented in Section 3.0.
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4.2.1  Process Alternatives

     Process alternatives are usually selected on the basis of the following:

     •  product demand;
     •  reliability of the process;
     •  economics;
     •  availability of required raw materials; and
     •  environmental considerations.

Those alternatives that appear practical should be considered further on the
basis of criteria such as:

     •  land requirements of the tanning facility, fuel storage facilities,
        waste storage facilities, and exclusion areas;
     •  release to air of dust, sulfur dioxide, nitrogen oxides, and
        other potential pollutants, subject to Federal, state, or local
        limitations;
     •  releases to water of heat, chemicals, and trace metals subject to
        Federal, state, and local regulations;
     •  water consumption rate;
     •  fuel consumption;
     •  social impacts of increased traffic as materials are transported to
        the site and wastes are transported from the site;
     •  social effects resulting from the influx of construction, operation,
        and maintenance crews;
     •  economics;
     •  aesthetic considerations for each alternative process; and
     •  reliability and energy efficiency.

     A tabular or matrix form of display often is helpful in comparing the
feasible alternatives.  The EID should present clearly and systematically the
methodology used to identify, evaluate, and select the preferred process
alternative.  Alternative processes which are not feasible should be dismissed
with an objective explanation of the reasons for rejection.
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4.2.2.  Design Alternatives

     In order to properly present  alternative facility designs available for
the project in the EID, the combination  of component systems available for
selection should be analyzed  and described for  the following factors:

     •  Economic.  This should  include capital  and operating costs.
     •  Environmental.  These should  be  documented and quantified where-
        ever possible.
     •  Engineering.   System  reliability and  safety should be discussed
        in conjunction with product requirements.

4.3  NO-BUILD ALTERNATIVE

     In all proposals  for  industrial  development,  the  alternative of not
constructing the proposed  new source  facility must be  considered.  This
analysis is not unique to  the development of  leather  tanning facilities  (see
Chapter IV, Alternatives to the Proposed New Source,  in  the USEPA document,
Environmental Impact  Assessment Guidelines for  Selected  New Sources  Industries,
October 1975).  The key aspects of the no-build alternative should be  identi-
fied  to include:

      •  Market Effect. Not  constructing the facility may result  in  pro-
        duct shortages.
      •  Industry Effect.   Not constructing the  facility  may cause  dated
        facilities  to be renovated.
      •  Technology  Effect.  Not constructing the facility may  only delay
        the need  for  expanded capacity,  which may allow time  for  improved
        technology  to be  incorporated into the facility.
      ,  Environmental Effect.  Not building the facility might avoid ad-
        verse environmental  effects at the proposed  site, but  may  therefore
        cause similar effects at a more sensitive site.

      Other factors  should be considered  (e.g.,  specific environmental issues)
as appropriate  for  the situation leading to the proposed action.
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                 5.0  REGULATIONS OTHER THAN POLLUTION CONTROL


     There are various regulations other than pollution control that may apply
to the siting and operation of leather tanning facilities.  Some Federal
regulations that may be pertinent to a proposed facility include, but are not
limited to, the following:


     •  Coastal Zone Management Act of 1972 (16 USC 1451 et seq.)

     •  Fish and Wildlife Coordination Act of 1974 (16 USC 661-666)

     •  National Environmental Policy Act of 1969 (42 USC 4321 et seq.)

     •  USDA Agriculture Conservation Service Watershed Memorandum 108  (1971)

     •  Wild and Scenic Rivers Act of 1969 (16 USC 1274 et seq.)

     •  Flood Control Act of 1944

     •  Federal-Aid Highway Act, as amended (1970)

     •  Wilderness Act of 1964

     •  Endangered Species Preservation Act, as amended  (1973)
        (16 USC 1531 et seq.)

     •  National Historical Preservation Act of 1966  (16 USC 470 et seq.)

     •  Executive Order 11593  (Protection and Enhancement of Cultural
        Environment, 16 USC 470)  (Sup. 13, May 1971)

     •  Archaeological and Historic Preservation Act of 1974  (16 USC 469
        et seq.)

     •  Procedures of the Council on Historic Preservation  (1973)
        (39 FR 3367)

     •  Occupational Safety and Health Act of 1970

     •  Executive Order 11988  (Floodplain Management - replaced  Executive
        Order  11296 on 10 August  1966)

     •  Executive Order 11990  (Wetlands)

     •  Energy Policy and Conservation Act of 1975

     •  Energy Conservation and Production Act of 1976
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Particular emphasis should be placed on obtaining the services of a qualified
archaeologist to determine the potential for disturbance of an archaeological
site, such as an early Indian settlement or a prehistoric site.  The National
Register of Historic Places also should be consulted for historic sites such
as battlefields.  The appropriate wildlife agency (state and Federal) should
be contacted to ascertain that the natural habitat of a threatened or endan-
gered species will not be affected adversely; other resource agencies also
should be consulted to avoid or minimize impacts to areas that previously have
been determined to be sensitive or uniquely important  (wetlands, floodplains,
prime farmlands, etc.).

     From a health and safety standpoint, most  industrial operations involve a
variety of potential hazards and  to  the extent  that these hazards could affect
the health of plant employees,  they  may be  characterized as potential environ-
mental impacts.  Company  policy should provide  and maintain safe and healthful
conditions for  employees  and establish operating practices that will result in
safe working conditions and efficient  operations.  All proposed plans to
maximize health and safety  should be described  in  the  EID.

     The plant  must be designed and  operated  in compliance with  the  standards
of the U.S. Department of Labor,  the Occupational  Safety  and  Health  Administra-
tion, and the appropriate state statutes  relative  to  industrial  safety.   Close
coordination with  local  and/or regional  planning and  zoning commissions  is
recommended to  determine  possible building or land  use restrictions.   State
and  local regulations may exist that affect the facility,  and the  EID  should
indicate that these have  been  considered.

     Table  9 presents  a  range  of  typical permits,  licenses, certifications,
and  approvals that could be required from local, regional,  state,  and  Federal
officials for  construction and operation of a major new source leather tanning
facility.   Although this list  doubtless  will vary between jurisdictions,  it is
intended primarily to be illustrative.  The new source NPDES  permit review
process normally  will be expedited by documenting in the EID  all known permits,
licenses,  and  approvals that are needed to construct and operate the proposed
plant,  and  the  status of each.
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            Table 9.   Typical permits,  licenses,  certifications,  and
                approvals required from Federal,  state,  regional,  and
                local authorities for construction and operation  of a
                typical new source leather tanning facility.
               Agency
   Local Planning Organization
   (regional, county, city)
•  Local Department of Public Works
•  Local Beautification Board
   Local Department of Development
   and Licensing
•  State Planning Department

•  State Fire Marshall
   State Department of Environ-
   mental Protection
            Requirement
Rezoning of plant site


Approval of access road rights-
of-way

Permit for filling or construction
operations in flood plains

Construction on public property if
required

Building permit for each structural
component of facility

Use and occupancy permits

Coastal zone permit, if required

Permit to store flammable liquids

Approval of facility for fire
protection

Water use and discharge permits

Test well permit

Commercial well permit

Permit for dewatering excavation

Permit for fuel oil storage  tanks

Permit for solid waste disposal

Dredging and construction of intake
structure

Sedimentation  control  approval

Noise control  approval

State water  quality certification

Construction permit for  combustion
equipment

Registration of gaseous  emissions
                                     126

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 Table 9.  Typical  permits,  licenses, certifications,  and  approvals  (continued).
                 Agency

•  State Air Pollution Control
   Department
    State  Board of Health
    State Department of Highways
    and Transportation
    US Environmental Protection
    Agency (Regional Office)
 •  US Army Corps of Engineers,
    (District Office)
    (COE, Washington Office)
                Requirement

•  Permit for construction of stationary
   source of air pollutants

•  Open burning of construction refuse

•  Review of indirect (mobile) emission
   sources

•  Permit to construct and operate
   approved sewage disposal and potable
   water facilities

•  Permit for  highway entrance of plant
   access road

•  Approval of public road improvements

•  Permits  for oversize or overweight
   vehicles

•  National Pollutant Discharge Elimina-
   tion System Permit (NPDES)  for waste-
   water discharge

•  Prevention  of Significant  Deteriora-
   tion of  air quality  (PSD)  permit prior
   to commencement of construction
   activities

 •  Spill Prevention,  Control,  and
   Countermeasure (SPCC)  plan

 •  Hazardous/toxic waste  disposal plan

 •  Permit  to construct  structures or
   works*  in navigable  waters (Section
    10, Rivers and Harbors Act of 1899)

 •   Permit  to dispose of dredged or  fill
   materials in waters  of the US (in-
    cluding wetlands)  (Section 404,
    FWPCA)

 •   Permit to construct  any dam or  dike
    in a navigable water of the US
    (Section 9, Rivers and Harbors Act of
    1899)
 *  Structures may  include piers, breakwaters, bulkheads, revements,  and aids
    to navigation;  works may include dredging, stream channelization, excava-
    tion and  filling.                 127

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Table 9.   Typical permits, licenses, certifications and approvals (concluded),
                Agency
   Occupational Safety and Health
   Administration
             Requirement

Permit to ocean dump dredged
materials (Section 103, Ocean Dump-
ing Act)

Permit to discharge refuse matter
into navigable waters of the US or
their tributaries (Section 13, The
Refuse Act 1899)

Test boring on Federal land

Certification of safety and health
criteria for plan operation (noise
in the work place, etc.)
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                                6.0  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 micro-
organism 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.
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Bend

That portion of the hide representing the entire hide cut down the backbone
with the belly and shoulder removed.

Biochemical Oxygen Demand (BOD,.)

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.

Slowdown

The amount of concentrated liquor wasted in a recycle system in order to
maintain an  acceptable  equilibrium  of contaminants  in any process liquor.

Blue

The state or condition  of hides subsequent to chrome tanning and prior  to
retanning.   Hides  in this stage of  processing are characteristically blue  in
color.

Buffing

A  light sanding operation applied to the grain  or underside of  leather  and
also  to splits.   Buffing smooths the grain surface  and  improves the nap of the
underside of the  leather.

Buffing Dust

Small pieces of  leather removed in  the  buffing  operation.   Buffing  dust also
includes  small particles  of  abrasive used  in  the operation  and  is  of  a  coarse
powder consistency.
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Carding

Method using a wire brush to disentangle wool.  One of the shearling finishing
processes.

Chemical Oxygen Demand  (COD)

A measure of the  amount of  organic matter  which  can be oxidized to carbon
dioxide and water by  a  strong  oxidizing agent under acidic conditions.
Generally expressed  in  mg/1.

Chlorine Contact  Tank

A  detention basin designed  to allow sufficient time  for  the  diffusion and
reaction  of  chlorine in a liquid for disinfection purposes.

Chromium  (Total)

Total chromium is the  sum of chromium occurring in the trivalent  and hexavalent
state.  Expressed in mg/1 as Cr.

 Clarification

 A physical means for the removal  of  suspended particles in a liquid by gravity
 sedimentation (settling).

 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.

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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
K2 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  com-
bined 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

 The  introduction of controlled  amounts of  moisture to the dryed  leather in
 order to  give it varying  degrees  of  softness.

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Corlum

The layer of hide between the epidermis and the flesh.  Also called the dermis.

Currying

Oil incorporation into  leather  in  a  low water system, classically used to
lubricate vegetable tanned  leather.

Degreasing

In pigskin and sheepskin tanneries a solvent or detergent is added to the drum
containing washed hides.  Grease is  removed  from  the  hides and recovered as a
by-product.

Deliming

The manufacturing  step  in the tanyard that is  intended  to remove  the  lime from
hides  coming from  the beamhouse.

Demineralization

The process of  removing dissolved minerals from water by ion exchange,  reverse
osmosis, electrodialysis, or other processes.

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.

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Dewatering

The process of removing a large part of the water content of sludges.

DO

Dissolved oxygen, measured in mg/1.

Drag-out

Loss of process chemicals and solution onto products during processing which
is 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 hori-
zontally.  This also may be  called a wheel.

Dry Milling

The rotating of leather in a large wooden  drum with no added  chemicals or
water.  Dry milling softens  the  leather.

Electrodialys is

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.
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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.

Eutrophication

The  excess  fertilization of receiving waters with nutrients,  principally
phosphates  and nitrates, found in wastewater which results  in excessive growth
of aquatic  plants.

Fatliquoring

A process by  which oils and related fatty substances replace natural  oils lost
 in the beamhouse and chrome tanning processes.  Regulates the softness and
pliability of  the leather.
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Finishing

The final processing steps performed on a tanned hide.  These operations
follow the retan-color-fatliquor processes, and include the many dry processes
involved in converting the hide into the final tannery product.

Fleshing

The mechanical removal of flesh and fatty substances from the underside of a
hide prior to tanning.  In the case of sheepskin tanning, fleshing is often
accomplished after the tanning process.

Float

The proper level or volume of skins or hides, chemicals, and water that is
maintained in any wet process unit (vats, drums, or processors) within the
tannery.

Floe

Gelatinous masses formed in  liquids by the addition of coagulants, by micro-
biological processes, or by  particle agglomeration.

Flocculation

The process of floe formation normally achieved by direct or induced slow
mixing.

Flume

An open, inclined channel or conduit for conveying water or water and hides.

Grab Sample

A single sample of wastewater which will indicate only the constituent  levels
at the  instant of collection; contrasted to a composite sample.

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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.
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Liming

The operations in the beamhouse where a lime solution comes in contact with
the hide.  Liming in conjunction with the use of sharpeners such as sodium
sulfhydrate is used either to chemically burn hair from the hide or ^o loosen
it for easier mechanical removal.  Hair burning normally utilizes higher
chemical concentrations.

Multi-Media Filter
A filtration device designed to remove suspended solids from wastewater by
trapping the solids in a porous medium.  The multi-media filter is charac-
terized by fill material ranging from large particles with low specific
gravities to small particles with a higher specific gravity.  Gradation from
large to small media size is in the direction  of normal flow.

Nitrogen, Ammonia

A measure of the amount of nitrogen which  is combined as ammonia  in waste-
water.  Expressed in mg/1 as N.

Nitrogen, Kjeldahl  (Total Kjeldahl Nitrogen or TKN)

A measure of nitrogen combined  in organic  and  ammonia form in wastewater.
Expressed in mg/1 as N.

Nitrogen. Nitrate

A measure of nitrogen combined  as nitrate  in wastewater.  Expressed  in mg/1 as
N.

Nutrient
 Any materials used by a living organism which serve to sustain its existence,
 promote growth, replace losses, and provide energy.  Compounds of nitrogen,
 phosphorus, and other trace materials are particularly essential to sustain a
 healthy growth of microorganisms in biological treatment.
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Outfall

The final outlet conduit or channel where wastewater or other drainage  is
discharged into an ocean, lake, or river.

Pack

Layers of salted hides  formed  at  the  slaughterhouse or hide curing firm
(usually approximately  20 to AO  feet  in area  and  5 to 6  feet high).

Paddle Vat  (Paddle)

A vat  with  a  semi-submerged  rotating  paddle arrangement  used for the mixing of
water  and chemicals  with the hide.

Pasting

The process step generally following the retan-color-fatliquor operations
whereby  the hide is attached to a smooth plate with a starch and  water paste
 and dried  in a controlled heated vessel.

pH

 The reciprocal logarithm of the hydrogen ion concentration in wastewater
 expressed as a standard unit.

 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 pre-
 cipitation of chromium salts  on the  hide.

 Plating

 The finishing operation in which 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.
                                         139

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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).
Parts per million.  The expression of concentration of constituents in waste-
water, 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.

Pul lery

A plant where sheepskin is processed by removing the wool and then pickling
before shipment to a tannery.

Pulp

Method of unhairing in which depilatory agents are used to dissolve hair
entirely in a few hours.

Re tanning

A second tanning process utilizing either the natural tanning material  (chromium
or vegetable extracts) or synthetic tanning agents.  Retanning imparts  special-
ized properties to the leather.
                                      140

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Reverse Osmosis

A process whereby water is forced to pass through semipermeable membranes
under high pressures.  Water passing through the membrane is relatively free
of dissolved solids; solids are retained in concentrated form on the feed side
of the membrane and are wasted.

Sanding

A dry operation performed  on the  tanned and fatliquored hide in order to
achieve the desired surface texture of  the  leather.   Sanding operations
include the use of abrasive or buffing  wheels.

Sedimentation
 Clarification (settling)

 Setting  Out
 A multi-purpose operation which smoothes and stretches the skin while  com-
 pressing and squeezing out excess moisture.  Puts hides into proper  condition
 for drying.
 Sharpeners
 Chemicals (such as sodium sulfide and sodium sulfhydrate) used in addition to
 lime to assist in the unhairing process.
 Shaving
 An abrasive, mechanical action used  to  correct errors in splitting and thus
 yielding a uniformly thick grain side or split.
                                         141

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Shavings

The waste products generated during the shaving operations.  These are
essentially small pieces of the tanned hide, which are approximately the size
of wood shavings.

Shearling

A lamb or sheepskin tanned with the hair retained.

Shoulder

That part of the hide between the neck and the main body of the hide.

Side

One-half of a hide, produced by cutting the hide down the backbone.  Normally
done to facilitate processing using smaller equipment than would be required
if full hides were processed.

Skin

The pelt or skin of animals smaller than mature cattle  (e.g., pigskin,  sheep-
skin,  calfskin).

Skiver

The thin layer  shaved or  cut off  the  surface  of finished  leather, principally
sheepskin.

Sludge

A concentrate  in the  form of a  semi-liquid  mass resulting from  settling of
suspended  solids  in the treatment of  sewage and industrial wastes.
                                     142

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A side which has been cut parallel to its surface to provide one large  piece
of leather of approximately uniform thickness and a thin, smaller piece of
non-uniform thickness called a split.

Staking

Mechanically softens the  leather by stretching and flexing it in every
direction.  Usually done  on automatic machines which move leather between
rapidly oscillating, overlapping fingers.

Sulfide

Ionized sulfur.  Expressed  in mg/1  as  S.

Suspended  Solids  (SS)

Constituents suspended  in wastewater which  can usually be removed by sedi-
mentation  (clarification) or  filtration.

Syntan

Synthetic  tanning  materials,  generally used in combination  with vegetable,
mineral, or formaldehyde tannages.   Syntans are  almost exclusively used  in
retanning  rather than tanning operations.

Tannin

The chemicals  derived from the leaching of bark, nuts, or other vegetable
materials  used in the vegetable tanning process.

Tanyard (Tanhouse)

That portion of the tannery in which the bating, pickling,  and tanning are
 performed on the hides or skins.
                                      143

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Toggling

Method of drying in which skins are kept in a stretched position by means of
clips called toggles.  The skin is attached to a perforated frame which is
slid into a drying oven.

Total Dissolved Solids  (TDS)

The total amount of dissolved materials  (organic and  inorganic) in wastewater.
Expressed in mg/1.

Total Solids  (TS)

The total amount of both  suspended  (TSS) and  dissolved (TDS)materials in waste-
water.  Expressed.in mg/1.

Trimming

The removal  of  the  ragged edges and inferior portions of hides and skins
either  before or  after tanning.  Trimming is normally accomplished by workers
using knives.

Trimmings

The hide  and leather scraps produced during the trimming operation.

 Unhairing

 The process whereby the hair is removed from the hide.

 Volatile Solids

 Solids, dissolved or suspended, which are primarily  organic  and during
 stabilization exert the significant portion  of the BOD5.
                                      144

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Weir
A control device placed in a channel or tank which facilitates measurement  or
control of the water flow.
                                      145

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                             7.0  REFERENCES


     The literature references in this section include cited references and

additional bibliographic references.  The listings immediately below are
short form citations arranged according to topics.  A complete listing of
full references, arranged alphabetically, follows the short form citations.


7 .1  REFERENCE LISTING BY TOPIC
          General
          Anonymous 1965
          0'Flaherty 1956
          O'Flaherty 1958
          0'Flaherty 1962
          O'Flaherty 1965
          Perry 1973
          Quarles 1979
          Reed 1972
          Schaklette
          Stcckdale 1941
          TCA 1978
          Thorstensen 1969
          Wiley 1977

          Markets & Demands
          Steadman 1977
          TCA  1978
          USBC 1978a
          USBC 1978b
          USDC 1976
          USDC 1978
          USDC 1979
          USEPA  1977b
          USEPA  1978d

          Trends
          TCA  1978
          USBC 1978a
          USBC 1978b
          USDC 1976
          USDC 1978
          USDC 1979
          USEPA  1976b
          USEPA  1977b
          USEPA  1978d
Processes
Anonymous 1965
Anonymous 1970
Davis 1973
Eye 1966
Eye 1970
France 1975
Freudrup 1970
Happich 1974
Hauck 1972
Koopman 1974
Larsen 1971
Money 1974
O'Flaherty 1956
O'Flaherty 1958
O'Flaherty 1962
O'Flaherty 1965
Perry 1973
Perkowski 1970
Pierce 1976
Robinson 1976
Steadman 1977
Steffman 1973
Stockdale 1941
Theis 1942
Thorstensen  1969
USEPA I977a
USEPA 1977d
van Vlimmeren  1972b
 van Vlimmeren  1976
Ward 1976
Williams-Wynn  1973
Wilson  1941
Wilson  1931

 Emissions
 Cheremisinoff  1976
 USEPA  1978b
 USEPA  1978c
 USEPA  1978e
Solid Wastes
Barber 1978
Bradford 1975
Cheremisinoff 1979
Dawson 1978
Giordano 1976
Keeney 1975
Loehr 1974
Lue-Hing 1974
Schaklette
SCS Engineers 1976
Touchton 1976
USEPA 1976a
USEPA 1976h
USEPA 1978d
USEPA 1979
Ward 1976

Waste Treatment
Adams 1977
Anonymous 1970
Anonymo us 19 7 7
Anthonisen  1974
Bailey 1966
Barber 1978
Barry 1976
Bell 1973
Black 1977
Brown 1976
Chen 1972
Cheremisinoff  1974
Cheremisinoff  1976
Davis 1973
Downing  1964
Eckenfelder 1970
Eichelberger  1976
Eldridge 1939
Envirogenics  1974
Eye 1966
Eye 1970
                                   146

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Waste Treatment  (cont.)
Eye 1972
Ferguson 1975
Ferguson 1976
France 1975
Freudrup 1970
Giusti
Hagan 1972
Hager 1976
Hager 1974
Happich 1974
Harnly 1940
Hauck 1972
Kennedy 1973
Kessick 1974
Koopman 1974
Larsen 1971
Leitz 1976
Lue-Hing  1974
Marks 1974
Minor 1974
Money 1974
Mulligan  1976
Numerow  1956
Parker  1970
Perkowski 1970
Perry  1973
Pierce  1976
Poats  1973
Prakasan 1974
Robinson 1976
 Siebert 1940
 Sproul  1966
 Steffan 1973
 Sweeny 1970
 Sweeny I973a
 Sweeny I973b
 Sweeny I973c
 Tomlinson 1975
 USDI 1967
 USEPA 1973a
 USEPA 1973b
 USEPA 1974a
 USEPA I974b
 USEPA 1974c
 USEPA 1975a
 USEPA I975b
 USEPA 1976b
 USEPA 1976d
 USEPA I976e
 USEPA 1976f
 USEPA 1977a
 USEPA 1977d
Waste Treatment (cont.)
USEPA 1978a
USEPA 1979
Ueno 1974
Ueno 1976
van Meer 1973
van Vlimmeren I972a
van Vlimmeren I972b
van Vlimmeren 1976
Ward 1976
Whitehouse 1967
Williams-Wynn 1973

Hazardous Waste
Anonymous 1970
Barber  1978
Barry 1976
Baumhardt 1972
Bradford  1975
Cheremisinoff  1979
Dawson  1978
Envirogenics 1974
Eye 1966
Ferguson  1975
Fields  1975
Giordano  1976
Giusti
Hager 1974
 Happich 1974
 Keeny 1975
 Kennedy 1973
 Marks 1974
 Minor 1974
 Robeck 1965
 Robinson 1976
 Sanders 1973
 Sax
 SCS Engineers  1976
 Sweeny 1970
 Sweeny 1973a
 Sweeny 1973b
 Sweeny I973c
 USEPA  1975a
 USEPA  1975b
 USEPA  1976a
 USEPA  1976c
 USEPA  1976g
 USEPA  1976h
 USEPA  1977b
 USEPA  1977c
 USEPA  1978d
 USEPA  1978f
 USEPA  1979
 Whitehouse  1967
                            147

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Regulations                      Human Health
McKee 1963                       USEPA 1974c
Quarles 1979                     USEPA 1976g
USEPA 1974e                      USEPA 1977c
USEPA 1975c                      USEPA 1978f
USEPA 1976c                      USEPA 1979
USEPA 1976d
USEPA 1976f
USEPA 1976g
USEPA 1979


Ecological Impacts
Baunhardt 1972
Bradford 1975
Cheremisinoff 1979
Envirogenics 1974
Fields 1975
Giordano 1976
Jain 1977
Keeney 1975
McKee 1963
Sanders 1973
Touchton 1976
USEPA 1976a
USEPA 1976c
USEPA 1976i
USEPA 1977c
USEPA 1978f
USEPA 1979
Wiley 1977
Modeling
USEPA 1978e
 Socioeconomics/Land  Use
 Jain  1977
 USEPA 1975c
 USEPA 1976i
 Wiley 1977
Aesthetics/Cultural Resources
Jain  1977
USEPA 1974c
USEPA 1975c
USEPA 1976i
Wiley 1977
Noise
TT3ETA"  1974c
USEPA  I974d
                          148

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7.2   ALPHABETICAL REFERENCE LISTING
Adams and Eckenfelder.   1977.  Nitrification design approach for high
     strength ammonia wastewaters.   Journal of the Water Pollution Control
     Federation, March.

Anonymous.  1965.  Leather  facts.   Peabody, MA.

Anonymous.  1970.  Report of  the Symposium on  Industrial Waste of the
     Tanning Industry.   Journal of  the American  Leather Chemists' Association.
     Supplement No.  15.

Anonymous.  1977.  Chementator.  Chemical  Engineering.  May 9, p. 86-87.

Anthonisen, A.C. et  al.   1974.  Inhibition of  nitrification by un-ionized
     nitrous acid.   Presented at the 47th  Annual Conference, Water Pollution
     Control Federation, October.

Bailey, D.A. and F.E. Humphreys.   1966. The  removal  of sulfide  from lime-
     yard wastes by  aeration.  British Leather Manufacturers' Research Associ-
     ation, Laboratory  Reports XV(1).

Bailey, D.A., M.K. Leafe, K.S.  Robinson, and  Stella Collins.  The role of
     high rate bio-filters  in the  leather  industry.   Journal of  the Society of
     Leather Trades' Chemists 56:200.

Barber, Lawrence K.   1978 (Manuscript).  Processing chrome  tannery effluent
     to meet best  available treatment standards.  Prepared  for USEPA Office of
     Research and  Development,  Cincinnati, Ohio.  155 p.

Barry, L.T. and B.P. Flynn.  1976.  Finding a home for the  carbon:  Aerator
      (powdered) or columnar (granular).  31st Purdue  Industrial  Waste Con-
     ference .

Baumhardt,  G.R. and L.F. Welch.  1972.  Lead uptake and corn growth with
     soil applied  lead.  Journal  of Environmental Quality 1:92-94.

Bell et  al.   1973.  Upgrading meat packing facilities to reduce  pollution
     waste'treatment systems.  Prepared for U.S. Environmental Protection
     Agency Transfer Program, Kansas City, MO.

Black, James  P. and James N. Andrews.  1977.   Upgrading poultry  processing
     waste  treatment with powdered activated carbon.   Proceedings  of  the ,Fifth
     Annual Industrial Pollution Conference, April 19, p. 310.

Bradford G R  et al.   1975.  Trace elment concentrations  of  sewage  plant
      effluent  and sludges; their  interactions  with soils and uptake  by plants.
      Journal  of  Environmental Quality  4:123-126.

Brown  and Lawrence.  1976.  Design and control  of nitrifying activated
      sludge systems.  Journal of the Water Pollution Federation.  July.
                                        149

-------
Chen,  Kenneth Y. and J. Carrell Morris.  1972.  Oxidation of sulfide by
     0»:  Catalysis and inhibition.  Journal of the Sanitary Engineering
     Division Proceedings of the American Society of Civil Engineers 98(SAI).

Cheremisinoff, P.N., F. Ellerbush, and A.J. Perna.  1979.  Industrial and hazard-
     ous wastes impoundment.  Ann Arbor Science Publishers, Inc., Ann Arbor, MI
     475 p.

Cheremisinoff, Paul N.  1976.  Carbon adsorption of air and water pollutants.
     Pollution Engineering.  July, p. 24-32.

Cooper, J.E., W.F. Happich, E.H. Bitcover, E.F. Mellon, and E.M. Filachione.
     1974.  Effect of flocculants on the sedimentation of organic solids in
     tannery unhairing effluents.  Proceedings, 29th Annual Purdue Industrial
     Waste Conference, 8 May 1974, Purdue University, West Lafayette, IN.

Davis, M.H. and J.G. Scroggie.  1973.  Investigation of commercial chrome-
     tanning systems, Part I-Part V.  Journal of the Society of Leather Tech-
     nologists and Chemists, Volume 57.

Dawson, Russell.  1978.  Leather tanning industry - sludge problems ahead.
     Sludge  (September-October), p. 24-27.

DeJohn, P.B. and A.D. Adams.  1975.  Treatment of oil refinery wastewater
     with granular and powdered activated carbon.  30th Annual Purdue Indus-
     trial Waste Conference, May 6.

Dostal, Kenneth A.  1979.  Memo, Kenneth Dostal, USEPA V, to Bob Pickett,
     USEPA V, 29 June 1979, 3 p.
        et al.  1964.  Effect of inhibitors on nitrification in the activated
     sludge process.  Institute of Sewage Purification Journal and Proceedings
     3(537).

Eckenfelder, W.  1970.  Water quality engineering for practicing engineers.
     Barnes and Noble, In:.., tlY.

Envirogenics Systems Company.  1974.  Status of developments of reductive
     degradation treatment of endrin-heptachlor and chlordane manufacturing
     was tes.

Eye, J. David and Stephen P. Graef.  1966.  Literature survey on tannery
     effluents.  Manual of American Leather Chemists Association 62:194-220.

    ,	.  1970.  Treatment of sole leather vegetable tannery wastes.
     Federal Water Pollution Control Administration, Department of the Interior.
     Grant ?H ib"- V?r-iR5, Program Number 12120,

Eye, J. David and David P. Clement.  1972.  Oxidation of  sulfirles in tannery
     wastewaters.  Journal of the American Leather Chemists Association  67(6).
                                     150

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Ferguson, J.F.  1976.  Combined powdered activated carbon biological contact
     stabilization treatment of municipal wastewater.  31st Purdue Industrial
     Waste Conference.

Ferguson, T.L.  1975.  Pollution control technology for pesticide formulators
     and packagers.  Final report under USEPA Grant No. R 801577 for the
     National Environmental Research Center, Office of Research and Develop-
     ment.

Fields, T. and A.W. Lindsey.   1975.  Landfill disposal of hazardous wastes:
     A review of literature and known  approaches.  USEPA Publication SW-165.
     Washington, DC.

France, H.G.  1975.  Recycle of tan liquor  from organic acid pickle/tan
     process.  American  Leather Chemists Association  70:206-219.

Freudrup, W. and Larrson.   1970.   Effect of depilating methods on the amount
     and composition of  wastewater. Das Leder  (Ger.) 21(81) in Chemical
     Abstracts 72, 36610v  (1970).

Giordano, P.M. and D.A.  Mays.   1976.   Yield and heavy metal content of several
     vegetable species grown in soil amended with sewage sludge.  In Bio-
     logical Implications  of Metals in the  Environment,  15th Annual Hanford
     Life Science Symposium, Richland, WA.

Giusti, D.M. et al.  Activated carbon  adsorption of  petrochemicals.  Journal
     of the Water Pollution Control Federation  46(5):947.

Hagan, James R. et al.   1972.   Investigations into the removal of color
     from biological treated vegetable tannery  wastes.  Master's Thesis, Uni-
     versity of Cincinnati.

Eager, D.G.  1976.   Waste treatment advances:  Wastewater treatment via
     activated carbon.   Chemical  Engineering Progress,  October,   p. 57-60.

Hager, D.G.  and J.L. Rizzo.  1974.  Removal of  toxic organics  from  waste-
     water by  adsorption with  granular activated carbon.   Presented at USEPA
     Technical Transfer Session on Treatment of Toxic Chemicals,  Atlanta,  GA,
     April  1974.

Happich   W.F.  et  al.   1974.  Recovery of proteins from lime sulfide effluents
      from unhairing  cattlehides.   Journal  of the American Leather Chemists'
     Association  69:50-65.

Harnley,  John W.  et  al.   1940.  Treatment  of tannery wastes at the  Griess-
      Pfleger Tannery,  Waukegan, Illinois.  Sewage Works Journal  XII(40).

Hauck  R A   1972.   Report on methods of chromium recovery and reuse from
      sp^nt'chrome tan liquor.   Journal of  the  American Leather Chemists'
      Association 67:422.


                                     151

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Jain, R.K.   1977.  Environmental  impact  analysis, a new dimension  in decision-
     making .

Keeney,  D.R. and L.M. Walsh.  1975.  Heavy metal availability in sewage sludge-
     amended soils.  Proceedings of the International Conference on Heavy
     Metals in the Environment, Toronto, Canada.

Kennedy, D.C.  1973.   Treatment of effluent from manufacture of chlori-
     nated pesticides with a synthetic, polymeric adsorbent amberlite XAD-4.
     Environmental Science and Technology 7(2):138.

Kessick, M.A. and B.M. Thomson.  1974.  Reactions between manganese dioxide
     and aqueous sulfide.  Environmental Letters 7(2).

Koopman, R.C.  1974.   Deliming with magnesium sulfate:  A new deliming pro-
     cess in which the pollution of wastewater is reduced.  Development and
     improvement of tanning methods, V, Section D, Institute for Leather and
     Shoes-TNO, June.

Larsen,  Bjarne C.  1971.  Utilization of the hide processor in reducing
     tannery effluent.  Presented at the 67th Annual Meeting of the American
     Leather Chemists' Association.  Mackinac Island, MI.

Leitz, Frank B.  1976.  Electrodialysis for industrial water cleanup.
     Environmental Science and Technology 10(2).

Loehr, Raymond C.  1974.  Agricultural waste management.  Academic Press,
     New York, NY.

Lollar,  Robert M.  1979.  Letter, Robert M. Lollar,  Tanners' Council Labora-
     tory, to Ronald McNeill, WAPORA, Inc., dated 2 May 1979.  4 p.

Lue-Hing, Cecil, et al.  1974.  Nitrification of a high ammonia content
     sludge supernatant by use of rotating disks.  Presented at the 29th
     Annual Purdue Industrial Waste Conference, May 1974.

Marks, D.R.  1974.  Testimony of Daniel R. Marks respecting technology
     to remove endrin from water.  FWPCA (307) Docket No. 1, State of
     Tennessee, County of Shelby, March 14, 1974.

McKee, Jack Edward and Harold W. Wolf.  1963.  Water quality criteria.
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     Control Board.  Publication No. 3-A.

Minor, Paul.  1974.  Organic chemical industry's wastewaters.  Environmental
     Science and Technology 8(7):620-625.

Money, C. and A. Adminis.  1974.  Recycling of lime-sulfide unhairing liquors.
     I.   Small scale trials.  Journal of the Society of Leather Technologists
     and Chemists 58(34).

Mulligan, Thomas J. and Robert D. Fox.  1976.  Treatment of industrial
     wastewaters.  Chemical Engineering Desk Book Issue, October 18, 1976.
     p.62.
                                      152

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Numerow, N.L.  1956.  Color and methods  for color removal.  Proceedings
     of the llth Industrial Waste  Conference, Purdue University, Ext. Sec.  91,
     West Lafayette, IN.

O'Flaherty, F. et al. (editors).   1956.  The chemistry and technology of
     leather.  Volume 1.  Reinhold Publishing Corporation, New York, NY.

             1958.  The chemistry  and  technology of leather.  Volume 2.
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    	.  1962.  The chemistry  and technology of leather.  Volume 3.
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             1965.  The chemistry  and technology of leather.  Volume 4.
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Outhmann, August C.   1945.  Tanning processes.  Hide and Leather Publishing
     Company.

Parker, Clinton E.  1970.  Anaerobic-aerobic  lagoon treatment for vegetable
     tanning wastes.  Prepared  for USEPA  Water Quality Office, Washington,
     DC.  84 p.

Perry, John H. (ed.).   1973.  Chemical  engineers' handbook.  McGraw-Hill,
     New York, NY.

Perkowski, S.  1970.  Water reuse systems in  the  leather industry.  Das
     Leder (Ger.) 21(63).

Pierce, Robert and Thomas C.  Thorstensen.  1976.  The recycling of chrome
     tanning liquors.   American Leather Chemistry Association 71:161-168.

Poats, Frederick J. and J. Naghski.   1973.  Alternatives for reducing water
     pollution in cattlehides processing  and  tanning.  U.S. Department of
     Agriculture, Economic Research Service,  MTS-191.

Prakasam, T.B.C. et al. 1974.   Approaches for the control of nitrogen with
     an oxidation ditch.  Proceedings of  the  1974 Agricultural Waste Manage-
     ment Conference.   Cornell  University,  Ithaca, NY. p. 421-435.

Quarles, John R.  1979.  Federal regulation of new industrial plants:  a
     survey of environmental  regulations  affecting the siting and construc-
     tion of new industrial plants and  plant  expansions.  Washington, DC
     239 p.

Reed, R.  1972.  Ancient skins, parchments, and leathers.  Seminar Press,
     New York, NY.

Robeck, G.G. et al.   1965.  Effectiveness of  water treatment processes in
     pesticides removal.  Journal of  the  American Water Works Association
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Robinson, John W.  1976.  Practical chrome  recovery/recycle/system.  Leather
     and Shoes, August  1976,  p. 38-42.
                                       153

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Sanders, H.O. et al.  1973.  Toxicity, residue dynamics and reproductive
     effects of phthalate esters in aquatic invertebrates.  Environmental
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Sax, N. Irving.  Dangerous properties of industrial materials.  3rd Edition.
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Schaklette, H.T., J.C. Hamilton, J.E. Boernger, and J.M. Bowles.  Elemental
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SCS Engineers, Inc.  1976.  Assessment of industrial hazardous waste prac-
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Siebert, C.L.  1940.  A digest of industrial waste treatment.  Pennsylvania
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Sproul, Otis J. et al.  1966.  Investigations on physical and chemical
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Steadman, Thomas R. et al.  1977.  Potential opportunities for increasing
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Steffan, A.G.  1973.  In-plant modifications to reduce pollution and pre-
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Stockdale, Leland G.  1941.  Handbook for shoe and leather processing.
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Sweeny, K.H. and J.R. Fischer.  1970.  Investigation of means for controlled
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	.  1973a.  Decomposition of halogenated organic compounds using
     metallic couples.  U.S. Patent No. 3,737,384, for U.S. Department of the
     Interior.

Sweeny, K.H. et al.  1973b.  Development and demonstration of process for
     the treatment of chlorinated cyclodiene pesticide manufacturing and
     process wastes.  Envirogenics Systems Company.

Sweeny, K.H. et al.  1973c.  Development of treatment process for chlorinated
     hydrocarbon pesticide manufacturing and processing wastes.  Envirogenics
     Systems Company, USEPA Contract 68-01-0083.

Tanners' Council of America (TCA).  1978.  Membership bulletin leather industry
     statistics, 1955-1975 edition.  Trade Survey Bureau, New York, NY.
                                      154

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Theis, Edwin R. and Fred O'Flaherty.   1942.  Conservation of chromium
     salts in the leather industry.  Hide and Leather and Shoes, May 9,  1942.

Thorstensen, Thomas C.   1969.   Practical  leather  technology.  Reinhold
     Book Corporation, New  York,  NY.

Tomlinson, H.D. et al.   1975.   Removal of  color from vegetable  tanning
     solution.  Journal  of  the Water  Pollution  Control  Federation 47(8):
     562-576.

Touchton, J.T. et al.   1976.   Residual effect of  liquid sewage  sludge on
     coastal Bermuda  grass  and soil chemical properties.  Journal of Environ-
     mental Quality  5:161-164.

U.S.  Bureau of  the Census (USBC) .  1978a.  "Footwear."   Current Industry Report
      Annual,  Summary, M31A.  Subscriber Service Secti   \,  Washington, DC.

_ .   I978b.   "Gloves and Mittens."  Current Industrial  Reports,
      Series MA23D(77), "Production of .Gloves and Mittens by Material and
      Type," Washington, DC.

U.S.  Department of  Commerce.  1976.  "United States Leather in  World Markets."
      Domestic and International Business Administration, Bureau of  Domestic
      Commerce, Washington, DC.

              1978.   Footwear  industry  revitalization program first annual
      progress report.  Washington, DC.

              1979.  1979 U.S.  industrial outlook.   Industry and Trade Ad-
      ministration, Washington, DC, p. 383-402.

 U.S. Department of the  Interior.   1967.  The cost  of clean water.  Volume
      III  Industrial Waste Profile No. 7,  Leather  Tanning and  Finishing.
      Federal Water Pollution  Control  Administration, Washington, DC, 60 p.

 U.S. Environmental Protection Agency.   1973a.  Development and demonstration
      of nutrient removal from animal  wastes.   USEPA Report No.  R2-73-095.

               1973b.   Secondary waste treatment for a small  diversified
 - tannery.  Office of Research and Monitoring,  Washington,  DC,  75 p.

               1974a.   Control  of  nitrogen in wastewater effluents.  Office
 - of Research and Development, Cincinnati,  OH.

               1974b    Development document for  effluent limitations guidelines
               source performance standards for the red  meat processing  segment
       aew
       of  the meat product and rendering processing point source  category
       USEPA Report No, 440/1-74-012-a.

               1974c.  Information on levels of environmental noise requisite  to
            "       n health and welfare with an adequate margin  of safety.  EPA
                    Performed by Office of Noise Abatement and Control,  Arlington,
       VA.   Variously paged, 159 p


                                        155

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         1974d.   Background  for  portable  air  compressor  noise  emission
 regulations.   Document No.  EPA-550/9-74-016.   Washington, DC.  Variously
 paged.

	.   1974e.  Development document  for proposed  effluent  limitations
 guidelines  and new source performance standards  for  the  leather  tanning
 and  finishing point source  category.   USEPA Report No. 440/1-74-016-a.

 	.   1975a.  Wastewater  treatment  technology  documentation  for  aldrin/
 dieldrin.   USEPA Report No.  68-01-3524.

	.   1975b.   Wastewater  treatment technology documentation  for  toxaphene.
 USEPA Report No. 68-01-3524.

	.   1975c.   Environmental  impact assessment guidelines  for selected
 new source industries.  Office of Federal Activities, Washington,  DC.  35
 p.  and  appendices.

	.   1976a.   Application of sewage sludge to cropland:   Appraisal
 of  potential hazards  of the heavy metals to plants and  animals. USEPA
 Report  No. 430/9-76-013.

	.   1976b.   Leather tanning and finishing waste management research
 and development program.   Office of Research and Development,  Cincinnati,
 OH., 39 p.

	.   1976c.   Quality  criteria for water.  USEPA Report No.  440/9-76-023.
	.   1976d.   Supplement for pretreatment to the development document
 for the leather tanning and finishing point source category.   USEPA
 Report  No.  440/1-6-082.

         1976e.   Wastewater treatment technology documentation for endrin
 manufacture and formulation.   USEPA Report No. 68-01-3524.

	.   1976f.   Federal guidelines - State and local pretreatment pro-
grams",  Appendix 8,  Volume 3.   Washington, DC.  p.  8-21-1 to 8-21-10.

	.   1976g.   National interim primary drinking water regulations.
 Office  of Water Supply, Washington, DC.  159 p.

         1976h.   Disposal of hazardous wastes, Manual on hazardous sub-
 stances in special wastes.   Washington DC.

         1976i.  Areawide assessment procedures manual, Volume II.
 Municipal Environmental Research Laboratory, Office of Research and
 Development, Cincinnati, Oh, 579 p.

	.   1977a.  Leather tannery waste management through process change,
 reuse,  and pretreatment.  USEPA Report No.  600/2-77-034.

	.   I977b.  Economic impact analysis of final pretreatment standards;
 Leather tanning and finishing industry.  Office of Analysis and Evalua-
 tion; Office of Hazardous Material.  Variously paged, 136 p.


                                    156

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	.  1977c.  Multimedia environmental goals for environmental  assess-
     ment, Volumes 1 and 2.  Office of Research and Development,  Research
     Triangle Park, NC.

	.  1977d.  Removal and recovery of sulfide from tannery wastewater.
     Office of Research and Development, Cincinnati, OH.

	.  1978a.  Biological treatment, effluent reuse, and sludge  hand-
     ling for the side leather tanning industry.  Office of Research and
     Development, Cincinnati, OH.  230 p.

	,  1978b.  Particulate control highlights:  Performance and  design
     model for scrubbers.  Office  of  Research and Development, Washington, DC.
     Prepared by S. Yung and S. Calvert, A.P.T., Inc.,  San Diego, CA.   19 p.

	.  1978c.  Particulate control highlights: fine particle scrubber
     research.  Office of  Research and Development, Washington, DC.  Prepared
     by S. Calvert and R.  Parker,  A.P.T.,  Inc.,  San Diego, CA.  12 p.

             1978d.  Economic  impact  analysis of hazardous waste management
     regulation on  the  leather tanning  industry.   Office of Analysis and
     Evaluation, Washington, DC.

           .  1978e.  Guideline on  air quality models.   Document No. EPA-
     450/2-78-027.   Washington,  DC.   Variously  paged.

           .  1978f.  Assessment of potential toxic releases  from  leather
	industry  dyeing operations.   Office of Research  and  Development,
     Cincinnati,  OH, 65 p.

              1979   (Manuscript).   Preliminary draft development  document
	foTTroposed  effluent limitations guidelines and new source  performance
   '  standards for the leather tanning and finishing industry.

Ueno,  Yasua.   1974.   Catalytic removal of sodium sulfide  from aqueous  solu-
     tions.   Journal of the Water Pollution Control Federation 46(12).

              1976   Catalytic removal of sodium sulfide from aqueous  solu-
	tlons'and application to wastewater treatment.  Water Research 10.

 van Meer, A.J.J.   1973.   Technical note.  Journal of the American Leather
      Chemists' Association 68:346.

 van Vlimmeren, P.J.  1972a.  Tannery effluent   Journal of the American
      Leather Chemists Association, September 1972., p. 395-396.

              1972b   Tannery effluent report to the members of the Effluent
 	Commission of'the International Union  of Leather  Chemists Societies.
      SoTrtal of the American Leather Chemists Association, October 1972,  p.
      431-465.
                                      157

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             1976.  New beamhouse development to simplify tannery waste-
     water management.  Journal of the American Leather Chemists Association
     71:318-335.

Ward, G.C. et al.  1976.  Recent developments in tannery process modifica-
     tion for reducing liquid and solid wastes.  American Leather Chemists
     Association 71:551-560.

Whitehouse.  1967.  A study of the removal of pesticides from water.
     University of Kentucky Water Resources Institute.  Research Report No. 8.

Wiley.  1977.  Handbook for environmental planning, The social consequences
     of environmental change.

Williams-Wynn, D.A.  1973.  No-effluent tannery processes.  Journal of the
     American Leather Chemists Association 68:8-10.

Wilson, John Arthur.  1941.  Modern practice in leather manufacturing.  Rein-
     hold Publishing Corporation, New York, NY.

Wilson, John Arthur and Henry Baldwin Merrill.  1931.  Analysis of leather
     and materials used in making it.  McGraw-Hill Book Company, Inc., New
     York, NY.
                                     158

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                                      TECHNICAL REPORT DATA
                              (Please read Instructions on the reverse before completing}
 1. REPORT NO.
  EPA-130/6-80-002
              3. RECIPIENT'S ACCESSION NO.
4. TITLE ANO SUBTITLE
 Environmental Impact  Guidelines for
 Leather Tanning and Finishing Industries
              5. REPORT DATE
               August 1980
              6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)

 Robert P.  Stevens, Don McCombs
              8. PERFORMING ORGANIZATION REPORT NO.

               625-050
9. PERFORMING ORGANIZATION NAME AND ADDRESS
 WAPORA, Inc..
 3301 Buckeye  Rd., N.E.
 Suite 301
 Atlantic, Georgia  30341
              10. PROGRAM ELEMENT NO.
              11. CONTRACT/GRANT NO.


               68-01-4157   Task 015
 12. SPONSORING AGENCY NAME AND ADDRESS
  EPA
  Office of Environmental Review
  401 M Street,  S.W.
  Washington,  D.C.  20460
              13. TYPE OF REPORT AND PERIOD COVERED
              14. SPONSORING AGENCY CODE


               EPA/100/102
 15. SUPPLEMENTARY NOTES

  EPA Task Officer:  Robert Pickett   (202)  755-9394
 16. ABSTRACT
   (See Attached)
17.
                                  KEY WORDS AND DOCUMENT ANALYSIS
                   DESCRIPTORS
                                                 b.lDENTIFIERS/OP£N ENDED TERMS
                            c. COSATl Field/Group
 Industrial Wastes/Waste  Treatment
 Water  Pollution
 Environmental Requirements
 Assessment
 Pollutant  Control
 Environmental
 Impact
 Document
 Assessment Methodologies
 Stationary Source
43F
680
910
18. DISTRIBUTION STATEMENT


  Release  Unlimited
19. SECURITY CLASS (ThisReport)
  Unclassified
                                                                             21. NO. OF PAGES
20. SECURITY CLASS (Thispage)

 Unclassified
                            22. PRICE
EPA Form 2220-1 (9-73)
                                                      OU.S. GOVERNMENT PRINTING OFFICE: 1980 311-132/98  1-3

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