United States
Environmental Protection
Agency
Industrial Technology Division
WH-552
Washington, DC 20460
September 1986
Water
Guidance Manual for
Leather Tanning and
Finishing Pretreatment
-------
-------
GUIDANCE MANUAL
FOR
LEATHER TANNING AND FINISHING
PRETREATMENT STANDARDS
September 1986
Prepared by:
Industrial Technology Division
Office of Water Regulations and Standards
and
Permits Division
Office of Water Enforcement and Permits
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, DC 20460
-------
-------
\ UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
? WASHINGTON, D.C. 20460
'I PflO?«-°
OFFICE OF
WATER
MEMORANDUM
SUBJECT: Guidance Manual for Leather Tanning and Finishing
Pretreatment Standards
FROM: Martha G. Prothro, Director
Permits Division (EN-336)
Devereux Barnes, Acting DirectorT^P*45%"""'
•Industrial Technology Division (TOI-552)
TO: Users of the Guidance Manual
..-•• This manual provides information to assist Control Authorities
and Approval Authorities in implementing the National Categorical
Pretreatment Standards for the Leather Tanning and Finishing
Point Source Category (40 CFR Part 425). It is designed to
supplement the more detailed documents listed as references in
the manual; it is not designed to replace than. If you need more
complete information on a specific item, you should refer to the
appropriate reference.
EPA developed this manual to fill several needs. First, it
should be useful to Control Authorities in responding to most
routine inquiries from regulated facilities. More complex inquiries
may require the use of the listed references.
Second, the manual addresses application of the combined
wastestream formula to integrated facilities with regulated and
unregulated wastestresras. It also provides current information
on removal credits, variances and reporting requirements. It
further incorporates the proposed amendment to the categorical
standards reflecting the settlement of litigation issues for the
final rule.
This manual is one of a series of industry-specific and progran-
specific guidance manuals for implementing the pretreatment program
(see references). Please feel free to write to either the Office
of Water Regulations and Standards (W3-552) or the Office of
Water Enforcement and Permits (EN-336) with suggestions, additions
or improvements.
-------
-------
ACKNOWLEDGEMENTS
We wish to acknowledge the considerable efforts and cooperation of the
many people whose contributions helped in the successful completion of this
document.
This document was prepared under the direction of Mr. Marvin Rubin,
Chief, Analysis and Support Branch, Industrial Technology Division and
Dr. James Gallup, Chief, Municipal Programs Branch. Mr. Donald Anderson and
Mr. Rex Gile of the Industrial Technology Division and Mr. Timothy Dwyer of
the National Pretreatment Program are to be acknowledged for their valuable
input. In addition, members of the Office of General Counsel are acknowledged
for their important contributions.
This document was prepared by Science Applications International
Corporation under EPA Contract No. 68-01-7043.
-------
-------
TABLE OF CONTENTS
ACKNOWLEDGEMENTS
1. INTRODUCTION. . ....... . ......................................... 1-1
1.1 HISTORY OF THE LEATHER TANNING AND FINISHING CATEGORICAL
PRETREATMENT STANDARDS .................................... 1-2
2. LEATHER TANNING AND FINISHING CATEGORICAL PRETREATMENT
STANDARDS ................................ ...................... 2-1
2.1 AFFECTED INDUSTRY ........................ ................. 2-1
2.2 PROCESS OPERATIONS ........................................ 2-1
2.3 SUBCATEGORIZATION ................. . ....................... 2-5
2.4 EXCEPTIONS FROM REGULATION ............................... 2-10
2.5 PRETREATMENT STANDARDS FOR THE LEATHER TANNING AND
FINISHING CATEGORY ...... .......... . ....................... 2-10
2.6 POLLUTANTS EXCLUDED FROM REGULATION ....................... 2-11
2.7 COMPLIANCE DATES. ................. . ....................... 2-11
2.8 SULFIDE EXEMPTION .................................... . ____ 2-11
,. 2.8.1 General Sulfide Criteria ........................... 2-17
2.8.2 Specific Sulfide Criteria... ................... .... 2-17
2.8.3 Effective Dates for Sulfide Applicability .......... 2-18
2.8.4 New Sources....... • ......... ....... ................. 2-18
2.9 TOTAL CHROMIUM EXEMPTION .......... . ...... .... ............. 2-18
3. TREATMENT TECHNOLOGIES ....... .......... . ....................... 3-1
3.1 IN-PLANT CONTROLS ........ . ........ . .................... ... 3-1
3.2 TREATMENT PROCESSES FOR SEGREGATED WASTESTREAMS ........... 3-4
3.3 END-OF-PIPE TREATMENT PROCESSES .......... ................. 3-5
3.4 SOLIDS HANDLING AND DISPOSAL ........................ ...... 3-6
4. REQUIREMENTS OF THE GENERAL PRETREATMENT REGULATIONS ........... 4-1
4.1 INTRODUCTION ...... .... ............................... ____ 4-1
4.2 CATEGORY DETERMINATION REQUEST ....... .......... . .......... 4-1
4.3 MONITORING AND REPORTING REQUIREMENTS OF THE GENERAL
PRETREATMENT REGULATIONS. ... ......................... . ____ 4-2
4.3.1 Baseline Monitoring Reports ........................ 4-2
4.3.2 Report on Compliance ............................... 4-4
4.3.3 Periodic Reports on Continued Compliance ........... 4-4
4.3.4 Notice of Slug Loading ...... ....................... 4-5
4.3.5 Monitoring and Analysis to Demonstrate Continued
Compl i ance ......................................... 4-5
4.3.6 Compliance Monitoring with Multiple Outfalls ....... 4-7
4.3.7 Signatory Requirements for Industrial
User Reports ....................................... 4-7
4.3.8 Recordkeeping Requirements ............. . ........... 4-7
-------
TABLE OF CONTENTS (Continued)
Page
4.4 THE COMBINED WASTESTREAM FORMULA 4-7
4.4.1 Monitoring Requirements for Industrial Users Using
the CWF.-. 4-9
4.4.2 Application of the CWF 4-9
4.5 REMOVAL CREDITS 4-9
4.6 FUNDAMENTALLY DIFFERENT FACTORS VARIANCE 4-14
4.7 LOCAL LIMITS 4-15
REFERENCES R-l
APPENDIX A: EXPANDED REVIEW CRITERIA FOR LEATHER TANNING SULFIDE
WAIVER APPLICATIONS
APPENDIX B: SULFIDE ANALYTICAL METHOD
-------
LIST OF TABLES
Tables Page
2.1 Leather Tanning and Finishing Industry Subcategories 2-7
2.2 Subcategory Raw Materials and Processes 2-8
2.3 Pretreatment Standards (PSE'S and PSNS) for Leather Tanning
and Finishing 2-12
2.4 Suggested Mass Effluent Limitations for Existing Sources
(PSES) 2-13
2.5 Suggested Mass Effluent Limitations for New Sources
(PSNS) •.. 2-15
4.1 Combined Wastestream Formulas 4-10
4.2 Example A: Combined Wastestream Formula Example
Calculation with Concentration Based Limits 4-11
Example B: Combined Wastestream Formula Example
Calculation with Alternative Mass Based Limits.. 4-12
Example C: Combined Wastestream Formula Example
Calculation For Integrated (multi-Subcategory) Facility 4-13
-------
LIST OF FIGURES
Figures
2.1 Leather Tanning and Finishing Industry Beamhouse Operation.... 2-2
2.2 Leather Tanning and Finishing Industry Tanyard Operation 2-4
2.3 Leather Tanning and Finishing Industry Retan-Wet Finish
Operation 2-6
3.1 Leather Tanning and Finishing Industry Pretreatment Process
Schematic for Indirect Dischargers (PSES & PSNS) 3-2
B.I Equipment Assembly B-5
-------
1. INTRODUCTION
The National Pretreatment Program establishes an overall strategy for
controlling the introduction of nondomestic wastes to publicly owned treatment
works (POTWs) in accordance with the overall objectives of the Clean Water
Act. Sections 307 (b) and (c) of the Act authorize the Environmental
Protection Agency to develop national pretreatment standards for new and
existing dischargers to POTWs. The Act made these pretreatment standards
enforceable against dischargers to publicly owned treatment works.
The General Pretreatment Regulations (40 CFR Part 403) establish
administrative mechanisms requiring nearly 1,500 POTWs to develop local
pretreatment programs to enforce Categorical Pretreatment Standards. These
Categorical Pretreatment Standards establish specific numerical limitations
based on an evaluation of available technologies for particular industrial
categories. The numerical limitations are imposed upon pollutants which may
interfere with, pass through or otherwise be incompatible with POTWs. As a
result of a settlement agreement, the EPA was required to consider development
of Categorical Pretreatment Standards for 34 industrial categories with a
primary emphasis on 65 classes of toxic pollutants.
This manual will provide guidance to POTWs on the implementation and
enforcement of the Categorical Pretreatment Standards for the Leather Tanning
and Finishing Category. This document has been prepared using primarily three
sources: Federal Register notices for the Leather Tanning and Finishing
regulations, the Final Development Document for Leather Tanning and Finishing
regulations, which provide technical support for the regulations, and the
Settlement Agreement between the Tanners' Council of America, Inc. and EPA,
dated December 11, 1984. Portions of this document which reflect changes
agreed to in the Settlement Agreement are noted for identification to the
reader. These changes must go through the standard public proposal and
promulgation rulemaking process to be incorporated into the categorical
standards. Proposed amendments incorporating the changes as a result of this
Settlement Agreement are scheduled for publication in the Federal Register in
the early part of 1986. Additional information on the regulations, manu-
facturing processes, and control technologies can be found in these sources.
1-1
-------
A listing of the references used, in the development of this manual is provided
at the end of this document.
1.1 HISTORY OF THE LEATHER TANNING AND FINISHING CATEGORICAL PRETREATMENT
STANDARDS
Pretreatment standards for the leather tanning and finishing category
were first established in 1974 for new sources (40 CFR Part 425, Subparts A-F,
•39 FR 12958), and in 1977 for existing sources (40 CFR Part 425, Subparts A-G,
42 FR 15696). In 1979 (44 FR 38746), EPA proposed revisions to Pretreatment
Standards for Existing Sources (PSES) and Pretreatment Standards for New
Sources (PSNS). On June 6, 1982, EPA published a notice of availability in
the Federal Register which made available for public review and comment
supplementary technical and economic information and data received after
proposal of the regulations (47 FR 23958). The Agency also summarized the
preliminary findings of how these supplementary record materials might
influence final rulemaking. On November 23, 1982 (47 FR 52848), the
regulations were promulgated. The Tanners' Council of America (TCA)
challenged the final regulations. On December 11, 1984, a Settlement
Agreement between TCA and EPA resolving issues from the challenge of the final
rule was executed.
The leather tanning and finishing industry currently includes 158
facilities operating within 9 subcategories. Of the 158 facilities located in
the United States, approximately 141 discharge into POTWs. Generally, the
tanneries are small family operations, although several are divisions of
larger corporations. Approximately 30 percent of the facilities employ less
than 50 people, and generate wastewater volumes of less than 100,000 gallons
per day. In addition, approximately 50 percent of the facilities are housed
in structures over 50 years old. Since the mid 1960's, the industry has
experienced a decline in production and profit and continually faces
international competition for its consumer markets.
1-2
-------
2. LEATHER TANNING AND FINISHING CATEGORICAL
PRETREATMENT STANDARDS
(40 CFR 425)
2.1 AFFECTED INDUSTRY • -
Leather tanning or finishing is the conversion of animal hides or skins
into leather. Cattlehides, sheepskins, and pigskins are the major hides and
skins used most often to manufacture leather.. To a lesser extent, hides and
skins of horses, goats, deer, elk, calves, and other animals are also tanned.
Cattlehide or cattle-like hide have short hair and are relatively heavy.
Deerskin, horsehide, cow bellies, splits (flesh side of tanned hides which is
usually processed separately into suede types of leather) and hides of a
similar nature are included in this group. Sheep or sheep-like skins have
long hair and are relatively light. Goatskin and other similar hides are
included in this group. Pig or pig-like skins have short hair or are hairless
and are relatively light. This group includes skins which have little hair,
yet typically require unhairing operations. The type of raw material (hides
or skins) and the amount of processing already performed on the raw materials
received by the facility determines the type of processes necessary to produce
finished or partially processed leather. Facilities covered by the Leather
Tanning and Finishing regulations are included in SIC 3111.
2.2 PROCESS OPERATIONS
It is the inner layer of an animal skin, which consists primarily of the
protein collagen, that is made into leather. Tanning is the reaction of the
collagen fibers with tannins, chromium, alum, or other tanning agents to help
stabilize or preserve the skin to make it useful. There are three major
groups of subprocesses required to make finished leather: Beamhouse oper-
ations; tanyard processes; and retanning and finishing processes. These
processes and types of wastewater generated are described below:
1. Beamhouse operations (summarized in Figure 2.1) consist of four
typical subprocesses": Side and trim; soak and wash; fleshing; and
unhairing. Side and trim is the cutting of the hide into two sides
and trimming of areas which do not produce good leather. In soak and
wash processes, the hides or sides are soaked in water for eight to
twenty hours to restore the moisture that was lost during curing.
Washing removes dirt, salt, blood, manure, and nonfibrous proteins.
2-1
-------
is
ill
50
CM
UJ
oc
CO
O g
ife
CO GC
7 UJ
2 Q-
U. O
O UJ
<§
o 2
CO
CD
2
cc
CO
(Z
UJ
ft
111
CO
"8
§i
UJUJ
occ
UJQ
S5
2
s
H-
•a
UJ
o
CO
cc
o
CO
o
UJ
t
CO
38
DJ £
•
3[
nL
c
3
•
•
.O
og
•3
•• ^y
E:
a:
L
•
5
r
:
c
E
t
CO*
o
u.
CO*
UJCO
Oui
UJ
OT
ce
_J
o
CO
CO
5
of
tree i <
CLO
1
eg
*?
X
t
UJ
£ ^
X
•"""
CO
z
UJ
H
O
cc
a.
.co
CO -I
H<
ZU
ao
O
CO
CO
UJ
<
ac
I
Q.UI
tux
00
a.
J
a
cc
z
cc
UJ
2-2
^"''^^-^
-------
Fleshing is a mechanical operation which removes excess flesh, fat,
and muscle from the interior of the hides. Cold water is used to
keep the fat congealed. The removed matter is normally recovered and
sold for conversion to glue. Unhairing involves using calcium
hydroxide, sodium sulfhydrate, and sodium sulfide to destroy the hair
(hair pulp) or remove hair roots (hair save), loosen the epidermis,
and remove certain .soluble skin proteins. A mechanical. unhai.ring
machine is used to remove hair loosened by chemicals in the hair save
process.
Beamhouse processes typically generate approximately 40 percent of
the wastewater volume and approximately 60 percent of the pollutant
load (except chromium) from a complete tannery. Washing and soaking
produce large quantities of wastewater containing dirt, salt,
manure, and other materials. Solvent degreasing, usually performed
only on sheepskins and pigskins, generates animal fat and waste skin
material, spent detergents, and solvents. Unhairing is performed in
an alkaline medium. The hair from the hair save method is usually
disposed of in a landfill; however, the hair pulp process completely
dissolves the hair. This process is the most significant source of
proteinaceous organic and inorganic (lime) pollutants characterized
by a high pH (10-12),, and substantial amounts of BOD, TSS, sulfides,
alkalinity, and nitrogen.
Tanyard processes (shown schematically in Figure 2.2) follow the
beamhouse operations and consist of bating, pickling, tanning,
wringing, splitting, and shaving. Bating involves the addition of
salts of ammonium sulfate or ammonium chloride used to convert the
residual alkaline chemicals present from the unhairing process into
soluble compounds which can be washed from the hides or skins. The
addition of bates, enzymes similar to those found in the digestive
systems of animals', facilitate the separation of the collagen protein
fibers and destroy most of the remaining undesirable constituents of
the hide, such as hair roots and pigments. Pickling prepares the
hides to accept the tanning agents (i.e., chrome) usually by adding
sulfuric acid to provide the acid environment necessary for chromium
tanning. In the tanning process, tanning agents such as trivalent
chromium, vegetable tannins, alum, syntans, formaldehyde, gluteral-
dehyde, and heavy oils, convert the raw collagen fibers of the hide
into a stable product no" longer susceptible to putrefaction or
decomposition. They also improve the dimensional stability,
resistance to heat, chemicals and abrasion, and flexibility of the
raw materials. Vegetable tanning is used.in the production of heavy
leathers such as sole leather and saddle leather. Chromium tanning
is usually preferred by the majority of leather users, i.e., shoe and
garment manufacturers. Blue hides (hides after beamhouse and tanyard
operations) are wrung to remove excess moisture through a machine
similar to a clothes wringer. Splitting adjusts the thickness of the
tanned hide to the requirements of the finished product and produces
a split ("drop") from the flesh side of the hide. These splits may
or may not be retanned and wet finished at the same facility.
Shaving removes any remaining fleshy matter from the flesh portion of
the hide.
2-3
H^^''"^ '
-------
OOC
ZUJ
<
O 5»->-
cozco<
o
QC
CO
a
CO
z
UJ
O^^ UJ
^^
CsJ
•
evi
CO
MM
In
il
CO
CO
OT
.
.09
• ^^
zg
CO
g
2
UJ
O
O
UJ
X
CO
UJ
a
UJ
X
UL
Off
£0 3
CO
o
CO
a:
UJ
i
UJ
r
UJ
CD
UJ
O
Z
o
a.
CO
T
o
-------
Wastewater from tanyard operations contain.inorganic chemical salts,
small amounts of proteinaceous hair and waste, and large amounts of
ammonia from the bating process. Pickling generates a highly acidic
waste (pH of 2.5-3.5) which contains salt. Spent chromium liquors
contain high concentrations of trivalent chromium in acid solution
with low concentrations of BOD and TSS and elevated temperatures.
Discharges, (blowdown) from vegetable tanning vats necessary to
maintain vegetable tanning liquor quality is highly colored and
contains significant amounts of BOD, COD, and dissolved solids.
3. Retanning and wet finishing processes (diagrammed in Figure 2.3) give
the tanned hide special or desired characteristics. The steps used
include retanning, bleaching, coloring, fatliquoring, and finishing.
Retanning is used to give the leather certain special characteristics
(different degrees of flexibility) which are lacking after the
initial tanning step. The most common retanning agents are chromium,
vegetable extracts (used to minimize variation between different
parts of the chromium tanned hide), and syntans (used for softer side
leathers and in making white or pastel leathers). In the sole
leather industry, sodium bicarbonate and sulfuric acid are used to
bleach the leather after tanning. Coloring involves combining dyes
(usually aniline based) with the tanned skin fibers to form an
insoluble compound. Dyes are added in the retanning wheels. Animal
or vegetable fatliquors are added to replace the natural oils lost in
.,the beamhouse and tanyard processes. Finishing includes all
•operations performed on the hide after fatliquoring, and includes
finishing to enhance color and resistance to stains and abrasions,
smoothing and stretching the s.kin, drying, conditioning, staking, dry
milling, buffing, and plating,
.These processes generate wastes with additional quantities of
trivalent chromium, tannins, sulfqnated oils, and spent dyes, which
are low in BOD and TSS, high in COD, and at elevated temperature.
In general, most tanneries perform the entire tanning process, from
beamhouse to wet finishing operations. A smaller number perform only
beamhouse and tanyard operations and sell their unfinished product (wet "blue"
stock) to other tanneries to produce specific leathers.
2.3 SUBCATEGORIZATION
Nine subcategories (Table 2.1) have been identified based on distinct
combinations of raw materials and leather processing operations. Table 2.2
summarizes the raw materials and processes used by the subcategories, which
are described in detail below:
1. Hair Pulp/Chrome Tan/Retan-Wet Finish - facilities which primarily
process raw or cured cattle or cattle-like hides into finished
2-5
-------
FIGURE 2.3
LEATHER TANNING AND FINISHING INDUSTRY
RETAN-WET FINISH OPERATION
FROM TANYARO
WATER
TANNING AGENTS
WATPS
BLEACHING AGENTS
RETAN
UNFIXED TANNING AGEN
[[3,
DYES & PIGMENTS
CHEMICAL EMUL3IFIER3. ^
BLEACHING
& COLORING
DYES, PIGMENTS
FATLIQUORS, WATER
FATLIQUORING
OILS
COATINGS
SETTING OUT
HANGING I {PASTING
DRYING
[TOGGLING! | VACUUM j
CONDITIONING
STAKING &
DRY MILLING
BUFFING
FINISHING
& PLATING
MEASURE
GRADE
i
SHIP
PASTING PLATE
WASH
BUFFING DUST
FINISH MACHINE EXCESS. fc
SPRAY MACHINE BATHS
I
TO SOLID
V/ASTE HANDLING
OR WASTE WATER
TREATMENT
2-6
-------
TABLE 2.1
LEATHER TANNING AND FINISHING INDUSTRY
SUBCATEGORIES
Subcategory Title
1 Hair Pulp, Chrome Tan, Retan-Wet Finish
s
2 Hair Save, Chrome Tan, Retan-Wet Finish
. 3 Hair Save or Pulp, Non-Chrome Tan,
Retan-Wet Finish
4 Retan-Wet Finish (Sides)
5 No Beamhouse
6 Through-The-Blue
7 Shearling
8 Pigskin
9 Retan-Wet Finish (Splits)
2-7
-------
Subcategory
1
2
3
4
6
7
8
9
TABLE 2.2
SUBCATEGORY RAW MATERIALS AND PROCESSES
Raw Materials
Cattlehide
Deer, Elk, Moose
Cattlehide
Calfskin
Cattlehide
Calfskin
Blue Sides
(cattlehide,
pigskins)
Unhaired and
Pickled Cattlehides,
Sheepskins,
Goatskins
Cattlehide
Shearlings
(wool-on)
Pigskins
Blue Splits
(drops)
(cattlehide)
Major Tanning and Finishing Steps
Beamhouse Tanyard
Hair Pulp Chrome Tan
Hair Save Chrome Tan
Hair Save Non-Chrome Tan
or Pulp
Chrome or
Non-Chrome Tan
Hair Pulp Chrome Tan
Hair Pulp
Chrome or
Non-Chrome Tan
Chrome or
Non-Chrome Tan
Retan-Wet
Finish
Yes
Yes
Yes
Yes
Yes
No
Yes
Yes
Yes
2-8
-------
leather by chemically dissolving the hair (hair pulp), tanning with
trivalent chromium, and retanning and wet finishing. Primary uses
for the final products of this subcategory include shoe uppers,
garments, upholstery, gloves, and lining material.
2. Hair Save/Chrome Tan/Retan-Wet Finish - facilities which primarily
process raw or cured cattle or cattle-like hides into finished
leather by chemically loosening and mechanically removing the hair
(hair save), tanning with trivalent chromium, and retanning and wet
finishing. Primary uses for the final products of this subcategory
include shoe uppers, handbags, garments, and gloves.
3. Hair Save or Pulp/Non-chrome Retan/Retan-Het Finish - facilities
which process raw or cured cattle or cattle-like hides into finished
leather by chemically dissolving (hair pulp), or loosening and
mechanically removing the hair (hair save); tanning primarily with
vegetable tannins, although other chemicals such as alum, syntans, or
oils may be used; and retanning and wet finishing. Primary uses for
the final products of this subcategory include sole leather, laces,
harnesses, saddle leather, mechanical strap and skirting leather, and
sporting good leathers (basketballs, footballs, softballs, baseballs,
etc).
4. Retan/Wet Finish (Sides) - facilities which process previously
unhaired and tanned "wet blue" grain sides into finished'leather
through retanning with trivalent chromium, syntans, vegetable
tannins, or other tanning agents, coloring with dyes, and wet
finishing processes including fatliquoring, drying (especially
pasting frame or vacuum), and mechanical conditioning. Primary uses
for the final products of this subcategory include .shoe uppers,
garments, and personal goods.
5. No Beamhouse - facilities which process previously unhaired and
pickled cattlehides, sheepskins, or pigskins into finished leather by
tanning with trivalent chromium or other agents, then retanning and
wet finishing. Primary uses for the final products of this sub-
category include garments, shoe uppers, gloves, and lining material.
6. Through-the-Blue - facilities which process raw or cured cattle or
cattle-like hides only through the "wet-blue" tanned state by
chemically dissolving or loosening the hair and tanning with
< trivalent chromium. No retanning or wet finishing is performed. The
"wet blue" stock produced by this subcategory is subjected to further
processing by plants in Subcategory 4 (grain sides) and plants in
Subcategory 9 (splits).
7. Shearling - facilities which process raw or cured sheep or sheep-like
skins with hair intact into finished leather by tanning with
trivalent chromium or other agents, retanning, and wet finishing.
Primary uses for hair on sheepskins (shearling) include hospital
products, wool lined suede coats and similar garments, or specialty
footwear, and seat covers.
2-9
-------
a Plaskin - facilities which process raw- or cured pigskins into
TTSflfiid leather by chemically dissolving the hair and tanning with
Trivalent chromium; then retanning and wet finishing;. Primary uses
for ?he final products of this subcategory include shoe uppers and
gloves.
Q Retan/Wet Finish (Splits) - facilities which process previously
unhaired and tinned splits into finished leather through retanning
Snd weTMSshlnS processes that include coloring, fatUquonng, and
mechanical conditioning. Primary uses for the final product 0this
subcategory include sueded leathers for garments, shoe uppers, and
other specialty or personal goods.
2.4 EXCEPTIONS FROM REGULATION
Operations which involve the manufacture of leather goods from finished
leather and which are exempt from coverage under the Leather Tanning and
Finishing Standards include: facilities in SIC 3131-3149, Shoe and Related
Footwear; and SIC 3151-3199, Gloves, Luggage, Personal Goods, and Miscella-
neous.
PSES regulations for chromium do not apply to small plants that process
less than 275 hides/.day in Subcategory 1, less than 350 hides/day in Sub-
category 3, and less than 3",600 splits/day in Subcategory 9, because of the
potentially disproportionate economic impact on these relatively small
facilities. However, small plants in Subcategories 1 and 3 would still be
subject to sulfide pretreatment standards and small plants in all sub-
categories would still be required to comply with the General Pretreatment
Regulations (40 CFR 403) including general and specific prohibitions and local
limits developed by the POTW Control Authority.
2.5 PRETREATMENT STANDARDS FOR THE LEATHER TANNING AND FINISHING CATEGORY
The pretreatment standards for new and existing sources are analagous to
BAT in that they control total chromium and apply to two groups of subcate-
gories, those with unhairing operations (Subcategories 1, 2, 3, 6, and 8), and
those without unhairing operations (Subcategories 4, 5, 7, and 9). Pre-
treatment standards for both existing and new facilities (PSES and PSNS) with
unhairing operations include concentration based standards for sulfide and
total chromium. Sulfides are controlled because of the potential for
interference resulting from the release of massive quantities of hydrogen
2-10
-------
sulfide gas in sewers, headworks, and sludge management facilities at POTWs.
PSES and PSNS for facilities without unhairing operations include only total
chromium concentration based standards. Alternate production based standards
based on kilogram per thousand kilograms of raw material are available for new
and existing sources, and may be used by the POTW. These alternate production
limits are based upon the concentrations specified in the standards and the
median water use ratios for existing sources and reduced water use ratios for
new sources contained 'in the settlement agreement. The pretreatment standards
for new and existing sources are shown in Table 2.3 and the suggested
alternate production based standards are presented in Table 2.4. The monthly
average limits are based upon eight days of sampling (approximately twice per
week) during any calendar month.
2.6 POLLUTANTS EXCLUDED FROM REGULATION
Of the 126 toxic pollutants authorized for regulatory consideration, EPA
has excluded 125 pollutants for the leather tanning and finishing industry.
Of these pollutants, 71 were not detected by approved 40 CFR Part 136
analytical methods or other state-of-the-art methods and 54 were excluded
because there is no economically achievable pretreatment technology available
for this industry that will remove these pollutants prior to discharge to
POTWs..
2.7 COMPLIANCE DATES
The Leather Tanning and Finishing compliance dates are as follows:
Pretreatment Standards ftfr November 25, 1985
Existing Sources (PSES)
Pretreatment Standards for On commencement of
New Sources (PSNS) discharge
Sulfide Pretreatment See Section 2.8.3
Standards for Existing Sources
2.8 SULFIDE EXEMPTION
A POTW receiving unhairing wastewaters from tanneries may certify to EPA
that the sulfide pretreatment standard applicable to a new or existing source
2-11
-------
TABU 2.3
CONCENTRATION BASED
PRETREATMENT STANDARDS (PSES AND PSNS)
FOR LEATHER TANNING AND FINISHING
Subcategory 1*:
Subcategory 2 :
Subcategory 3*:
Subcategory 6 :
Subcategory 8 :
Pollutant
Hair Pulp, Chrome Tan, Retan-Wet Finish
Hair Save, Chrome Tan, Retan-Wet Finish
Hair Save or Pulp, Non-Chrome Tan, Retan-Wet Finish
Through-The-Blue
Pigskin
Daily Maximum
(mg/1)
Maximum Monthly
Average (mg/1)
Sulfide
Total Chromium
24
12 8
between 7.0 and 10.0 (except for
Subcategory 3 which is not less than 7)***
Subcategory 4 :
Subcategory 5 :
Subcategory 7 :
Subcategory 9*:
Pollutant
Retan-Wet Finish (sides)
No Beamhouse
Shearling
Retan-Wet Finish (splits)
Daily Maximum
(mg/1)
Total Chromium
PH
Maximum Monthly
Average (mg/1)
19 12
between 6.0 and 10.0
*The promulgated regulation exempts small tanneries from the chromium
pretreatment standards only (PSES and PSNS) as follows:
Subcategory 1: processes less than 275 hides/day**
Subcategory 3: processes less than 350 hides/day**
Subcategory 9: processes less than 3600 splits/day**
** Small plant specifications in the regulations added in a correction notice
(see the Federal Register for June 30, 1983, 48 FR 30115), including annual
weight basis and number of working days underlying the daily hide and split
limits, will be deleted. Based upon the Settlement Agreement the
production basis will be process of hides or splits as shown.
***This change to Subcategory 3 pH limitation is a result of the Settlement
Agreement.
2-12
-------
TABLE 2.4
ALTERNATE PRODUCTION-BASED EFFLUENT LIMITATIONS
FOR EXISTING SOURCES (PSES)*
(kg/kkg of raw material)
Subcategory 1: Hair,Pulp, Chrome Tan, Retan-Wet Finish
Maximum Monthly
Pollutant Daily Maximum , Average
Total Chromium 0.54 0.36
Sulfide ' 1.08 --
Total chromium standards do not apply to plants processing less than 275
hides/day.
Subcategory 2: Hair Save, Chrome Tan. Retan-Wet Finish
Maximum Monthly
Pollutant Daily Maximum Average
Total Chromium 0.50 0.33
Sulfide 1.00 I-
Subcategory 3: Hair Save or Pulp, Non-Chrome Tan. Retan-Wet Finish
Maximum Monthly
Pollutant Daily Maximum Average
Total Chromium 0.45 0.30
Sulfide 0.90
Total chromium standards do not apply to plants processing less than 350
hides/day.
Subcategory 4: Retan-Wet Finish (Sides)
Maximum Monthly
Pollutant Daily Maximum Average
Total chromium 0.76 0.48
•Subcategory 5: -No Beamhouse
Maximum Monthly
Pollutant Daily Maximum Average
Total Chromium 0.63 0.40
*The limits have been revised to reflect the median water use ratios for
existing sources contained in the settlement agreement.
2-13
-------
TABLE 2.4 (continued)
ALTERNATE PRODUCTION-BASED EFFLUENT LIMITATIONS
FOR EXISTING SOURCES-. (PSES)*
(kg/kkg of raw material)
Subcategory 6: Through-The-Blue
Pollutant
Total Chromium
Sulfide
Daily Maximum
0.21
0.42
Maximum Monthly
Average
0.14
Subcategory 7: Shearling
Pol1utant
Total .Chromium
Daily Maximum
1.49
Maximum Monthly
Average
0.94
Subcategory 8: Pigskin
Pollutant ,
Total Chromium
Sulfide
Daily Maximum
0.50
1.00
Maximum Monthly
Average
0.33
Subcategory 9: Retan-Wet Finish (Sides)
Pollutant
Total Chromium
Daily Maximum
0.47
Maximum Monthly
Average
0.30
Total chromium standards to not apply to plants processing less than 3,600
splits/day.
*The limits have been revised to reflect the median water use ratios for
existing sources contained in the settlement agreement.
2-14
-------
TABLE 2.5
ALTERNATE PRODUCTION-BASED EFFLUENT LIMITATIONS
FOR NEW SOURCES (PSNS)*
(kg/kkg of raw material)
Subcategory 1: Hair Pulp, Chrome Tan. Retan-Wet Finish
Maximum Monthly
Pollutant Daily Maximum Average
Total Chromium 0.43 0.29
Sulfide 0.86
Total chromium standards do not apply to plants processing less than 275
hides/day.
Subcategory 2: Hair Save, Chrome Tan, Retan-Wet Finish
Maximum Monthly
Pollutant Daily Maximum Average
Total Chromium 0.50 0.33
Sulfide 1.00
Subcategory 3: Hair Save or Pulp, Non-Chrome Tan. Retan-Wet Finish
Maximum Monthly
Pollutant Daily Maximum Average
Total Chromium 0.42 0.28 .
Sulfide 0.84
Total chromium standards do not apply to plants processing less than 350
hides/day.
Subcategory 4: Retan-Wet Finish (Sides)
Maximum Monthly
Pollutant Daily Maximum Average
Total chromium 0.73 0.46
Subcategory 5: No Beamhouse
Maximum Monthly
Pollutant Daily Maximum Average
Total Chromium 0.60 0.38
*The limits have been revised to reflect the reduced water use ratios for new
sources contained in the settlement agreement.
2-15
-------
TABLE 2.5 (continued)
ALTERNATE PRODUCTION-BASED EFFLUENT LIMITATIONS
FOR NEW SOURCES (PSNS)*
(kg/kkg of raw material)
Subcategory 6: Through-The-Blue
Pollutant
Total Chromium
Sulfide
Daily Maximum
0.21
0.42
Maximum Monthly
Average
0.14
Subcategory 7: Shearling
Pollutant
Total Chromium
Daily Maximum
1.49
Maximum Monthly
Average
0.94
Subcategory 8: Pigskin
Pollutant •
Total Chromium
Sulfide
Daily Maximum
0.41
0.82
Maximum Monthly
Average
0.27
Subcategory 9: Retan-Wet Finish (Sides)
Pollutant
Total Chromium
Daily Maximum
0.40
Maximum Monthly
Average
0.25
Total chromium standards do not apply to plants processing less than 3,600
splits/day.
*The limits have been revised to reflect the reduced water use ratios for new
sources contained in the settlement agreement.
2-16
-------
should not apply, provided that the POTW has evaluated the site specific
factors that determine the degree of interference attributable to high sulfide
concentrations that may present serious hazards to human life.
2.8.1 General Sulfide Criteria
When certifying to the EPA that the sulfide standards should not apply,
the POTW must have considered, at the minimum:
1. The presence and characteristics of other industrial wastewater which
may increase or decrease sulfide concentrations and/or pH...
2. The characteristics of the sewer/interceptor collection system which
either minimize or enhance opportunities for release of hydrogen
sulfide gas.
3. The characteristics of the receiving POTWs headworks, preliminary and
primary treatment systems, and sludge holding and dewatering
facilities which either minimize or enhance opportunities for the
release of hydrogen sulfide gas.
4. The occurrence of any prior sulfide related interference.
2.8.2 Specific Sulfide Criteria
The severity of the sulfide problem varies by POTW as a result of the
physical characteristics of a POTW's collection system, headworks, and sludge
management facilities, and the particular mix and types of industrial and
municipal wastewaters. In order to assist POTW's in making the required
certification and to aid Regional Offices in reviewing any certifications they
may receive, EPA has prepared guidance interpreting the criteria for the
sulfide certification set forth in the preamble accompanying the final
regulation. Appendix A presents the expanded criteria which were developed by
EPA Region V personnel in response to certifications submitted by POTWs with a
potential for significant sulfide problems stemming from complex local
conditions. This guidance will be very useful in those cases where a POTW
receives wastewater from a number of tanning facilities whose wastewater flows
constitute a significant percentage of the wastewater received by the POTW.
In relatively simple cases, the certifying POTW and the reviewing Regional
Office may not need to employ this guidance. The POTW and the Regional Office
should make the appropriate decision on whether to employ the guidance on a
case-by-case basis.
2-17
is'?^.~-^.-'"'^-f^-~-*?~i~*i?j^?*\r'^
-------
2.8.3 Effective Dates for Sulfide Applicability
The final regulations provided a series of deadlines for POTW's to make
findings and notify the public as to their intentions with respect to site
specific applications of the sulfide waiver. These deadlines included a
requirement that EPA publish a notice in the Federal Register identifying
those facilities to which the sulfide pretreatment standards shall not apply.
Several notices have been published by Regional Offices, however,
additional provisions to be added to the regulations as a result of the
Settlement Agreement will have the effect of altering the application .process.
These new provisions shall allow a POTW at any time to determine that there
have been changed circumstances and to initiate the proceedings and make a
determination whether the sulfide standards apply.
The POTW which has granted a waiver can also determine that there have
been changed circumstances which justify the application of the standards. In
this later case a facility shall comply with the sulfide pretreatment
standards no later than 18 months from the date of publication in the Federal
Register notice identifying the facility.
2.8.4 New Sources
A POTW may certify that the sulfide pretreatment standards do not apply
to a new source. This certification must be submitted prior to the commenc-
ment of discharge of sulfide and must conform, at a minimum, with the above
criteria.
2.9 TOTAL CHROMIUM EXEMPTION
The pretreatment standards for chromium are not applicable to plants with
mixed subcategory operations if the greatest part of the plant's production is
in either subcategory 1, 3 or 9 and if the total plant production is less than
the specified number of hides or splits per day for the particular subcate-
gory. The intent of this exemption is to exclude small plants from the
chromium pretreatment standards, not to exclude processing operations at
medium or large plants.*
* This intent was clarified as part of the Settlement Agreement.
2-18
-------
3. TREATMENT TECHNOLOGIES
The treatment technologies described in this section are applicable to
the control, and treatment of wastewaters generated by the leather tanning and
finishing industry. The process schematic in Figure 3.1 illustrates the
technology basis for the pretreatment limitations. In addition to in-plant
controls, the treatment technology consists of screening, catalytic oxidation
of sulfides in segregated unhairing wastestreams (applicable to plants in
Subcategories 1, 2, 3, 6, and 8, which incorporate sulfide unhairing oper-
ations), equalization and coagulation-sedimentation with lime for chromium
control of the segregated tanyard and retan-wet finish wastewaters, and
neutralization of the combined wastestream. These treatment processes are
described in this section.
3.1 IN-PLANT CONTROLS
In-plant controls have often been found to be very cost effective in
cleaning up industrial wastewater. In-plant controls applicable to the
leather tanning and finishing industry include good housekeeping, stream
segregation, water conservation, recycle or reuse of concentrated liquors,.and
process modifications.
1. Good housekeeping practices include general procedures and management
functions to (1) reduce chemical spills resulting from carelessness, (2)
prepare a' program to control and clean up unavoidable chemical spills, (3)
repair or replace faulty equipment, and (4) install automatic monitoring
devices to detect abnormal discharges of hazardous gases or polluting
substances.
2. Stream segregation is the intital step in implementing many in-plant
controls. Because of the difference in wastesteam characteristics from
beamhouse (high pH and sulfides) and tanning (low pH and chromium) operations,
more efficient control can be achieved through the use of a treatment process
specifically designed for the related pollutant. Further segregation of spent
solvents, concentrated chromium bearing liquors, buffing dust scrubber water,
and pickling liquors lead to the reuse or recycling of spent liquors and may
decrease the size of the treatment facility for a specific pollutant. In
3-1
-------
s
i
o
I*
s5
I
lo
35
i2co
5 UJ (T
-------
general, wastestream segregation provides the opportunity for lower water use
requirements and reduced usage of processing chemicals, thereby reducing the
volume and pollutant content of wastewater generated and the cost of treating
these wastewaters.
3. Water conservation attempts to reduce water usage in the tannery
operations. Batch rinsing employing a closed door rotating tanning drum or
using countercurrent washing, has been found to be very efficient. Hide
processors provide the opportunity for lower floats and facilitate washing and
waste liquor reuse. Dry bag house collection of buffing dust rather than wet
scrubbing also eliminates a source of wastewater and very fine suspended
solids which can be difficult to treat. Where this is not implemented, the
separation of buffing,dust scrubber water for treatment and reuse also has
been proven to be effective. An additional method of conserving water is
recycling cooling water and pasting frame water rather-than using once through
systems.
4. Reuse of process solutions reduces water use and therefore reduces
the discharge of a particular pollutant, the use of highly concentrated
depilatory chemicals in the hair removal process provides the opportunity for
increased sulfide liquor reuse. The simplest method of sulfide reuse involves
screening, storing, and refortifying the spent liquor before reuse. Three
methods are generally used to recover chromium from process wastewaters: (1)
isolating the spent chromium tanning solutions for reuse in the pickling
process; (2) concentrating segregated spent chromium tanning liquors by
chemical precipitation for use in formulating new chromium tanning liquors;
and (3) incinerating chromium-bearing sludges and recovering hexavalent
chromium from the incinerator ash. The recovery of vegetable tannins using
the Liritan method substantially reduces the amount of tannins discharged in
the wastewater and enables tanners to economize in the purchase of the
vegetable tannins. The Liritan process employs intermediate coloring vats
which act as barriers to salt carryover from pickling into the tannery
liquors.
5. Manufacturing process modifications include alternative hide
preservation methods, reduction of lime in unhairing operations, enzyme
3-3
-------
unhairing for hair-save operations, in-situ sulfide, oxidation, and ammonia
substitution. Alternative hide preservation methods are designed to reduce
the salt content of hides, and, in turn, wastewaters. These methods are
intended to preserve the untanned hides for shorter periods of time.
Alternative preservatives include refrigeration; boric acid; combinations of
zinc, chlorite, or h'ypochlorite, and sodium pentachlorophenate; and sulfide
combined with acetic acid. Of these, the latter two are the most economical.
The reduction of lime reduces the amount of sludge produced and decreases the
amount of acid required for pH neutralizaton. Enzyme unhairing, a method used
for removal of hair when the hair will be sold, reduces the total nitrogen
content in the unhairing wastes as compared with hair wastes that contain the
fullydissolved hair from the hair-pulp method. In-situ sulfide oxidation is
performed in the unhairing vessel and converts sulfide to sulfate with
manganese (II) ion as a catalyst. It is most often used as an end-of-pipe
treatment process and will be described in a later section. Substitution of
ammonium sulfate by epsom salts (magnesium sulfate heptahydrate) can be used
in deliming to reduce ammonia concentrations. However, loss in the hide
weight, non-uniform grain of pickled bellies, and build-up of magnesium salts
are sometimes experienced.
3.2 TREATMENT PROCESSES FOR SEGREGATED WASTESTREAMS
Treatment processes that apply to the segregated wastestreams from the
beamhouse and from the tanyard and retan-wet finish operations are screening,
sulfide oxidation, protein precipitation, and reduction and removal of
ammonia, as described below.
1. Screening is employed to protect downstream equipment and to remove
suspended solids such as hair, buffing dust, and hide and leather scraps from
fleshing and hide washing operations. Several types and sizes of screens are
often installed, but should include bar screens (already in place at most
tanneries) and fine screens (e.g., 0.040 inch openings) which few tanneries
have in place. Operated correctly, screening equipment provides for efficient
and necessary preliminary wastewater treatment.
2. Sulfide Oxidation in tannery wastes is accomplished most often by
catalytic oxidation, chemical oxidation, and precipitation. In catalytic
3-4
-------
oxidation of sulfide, the sulfide bearing wastes are collected in a suitable
tank, manganese (II) ion is added, and the waste is aerated. Thiosulfate is
the primary end product, although sulflte and sulfate also are present.
Catalytic oxidation is widely used and has the advantage of reducing the
alkalinity of unhairing liquor. Hydrogen, peroxide can also be used to oxidize
sulfides in tannery wastes. When the pH is reduced to below 8.0, the addition
of hydrogen peroxide causes sulfide to be oxidized to sulfur. The disadvan-
tage of-this method is the high cost of the chemicals.
Sulfide precipitation by the addition of iron salts minimizes-the
possibility of oxidized sulfur reverting to sulfide. However, a large
quantity of relatively expensive chemicals are required and more solid waste
is generated.
3. Flue Gas Carbonation for Protein Precipitation is a method in which
carbon dioxide from the tannery's boiler stack gas is used as an inexpensive
source of acid to neutralize caustic alkalinity and reduce pH. At the lower
pH, protein in the beamhouse wastes flocculate and settle. The sludge
generated is rich in lime.and protein and may be used as a soil conditioner or
protein supplement in animal feed. Removing colloidal proteins also enhances
coagulation and sedimentation downstream.
4. Ammonia Reduction by physical means are most effective when applied
to concentrated waste, such as the deliming wastestream. Evaporating water
from the waste enables ammonium sulfate to be precipitated and removed. With
the addition of phosphoric acid it is possible to precipitate the ammonia as
insoluble calcium ammonium sulfate. Ammonium sulfate is also insoluble in a
solution of ethanol and water. Additionally, reverse osmosis can be used to
concentrate aqueous ammonium sulfate.
3.3 END-OF-PIPE TREATMENT PROCESSES
End-of-pipe treatment processes are applied to entire wastestreams and
may include flow equalization, sedimentation, coagulation-sedimentation,
biological treatment, and filtration.
3-5
-------
1. Flow Equalization improves the consistency of other treatment
processes' performance by dampening flow surges, diluting slugs of concen-
trated wastes, partially neutralizing high and low pH waste fractions, and
providing a relatively constant rate of flow to downstream treatment pro-
cesses.
2. Sedimentation is one of the most widely used processes to treat
individual and combined wastewater streams. Primary clarification removes
suspended solids from tannery wastewater that are sources of 800, COD, TKN,
and certain toxic pollutants, particularly chromium.
3. Coagulation-Sedimentation - Coagulation with alum, lime, and polymer
significantly improves the performance of sedimentation in removing suspended
solids, chromium, and other pollutants in the wastestream. When applied to
segregated wastestreams, coagulation-sedimentation provides cost-effective
pretreatment to achieve PSES and PSNS. In conjunction with other treatment
processes, this method has shown to be very effective in removing pollutants.
4. •Biological Treatment removes colloidal and dissolved biodegradable
organic matter, suspended solids, and some toxic pollutants. Trickling
filters, lagoons, activated sludge, and rotating biological contactors (RBCs)
are all biological treatment processes that may be employed. The activated
sludge process generally is preferred due to its greater consistency in
pollutant removal capability, especially its ability to operate more effi-
ciently in cold weather. Upgraded biological treatment incorporates nitrifi-
cation capabilities and the addition of powdered activated carbon to aeration
basins.
5. Filtration in deep bed granular media filters is a physical-chemical
process that involves removal of residual suspended solids by different
filtered media, such as different grades of sand and anthracite coal. Because
of the relationship between suspended solids levels and total chromium,
multimedia filtration results in additional removal of chromium.
3-6
-------
3.4 SOLIDS HANDLING AND DISPOSAL
Thickening of sludges is designed so that smaller and more efficient
equipment may be used in dewatering the sludge. Water removal and the
corresponding reduction in weight and volume of the sludge is the main
objective of the dewatering process. Common processes for dewatering include
vacuum filtration, sludge drying on beds, centr-ifugation, and pressure
filtration. Conditioning is performed to improve dewatering rates, solids
capture, and comparability. Stabilization of sludge reduces its putrescible
and pathogenic characteristics, thereby reducing the impact to the environment
upon disposal.
3-7
-------
-------
.4. REQUIREMENTS OF THE GENERAL PRETREATMENT REGULATIONS
4. L INTRODUCTION
This section provides a brief overview of the General Pretreatment
Regulations and identifies those provisions of the Regulations which have a
direct bearing on the application and enforcement of Categorical Pretreatment
Standards for the Leather Tanning and Finishing category.
The General Pretreatment Regulations for Existing and New Sources (40 CFR
Part 403) establish the framework and responsibilities for implementation of
the National Pretreatment Program. The effect of 40 CFR Part 403 is essen-
tially three-fold. First, the General Pretreatment Regulations establish
general and specific discharge prohibitions as required by Sections 307(b)
and (c) of the Clean Water Act. The general and specific prohibitions are
described in Section 403.5 of the Pretreatment Regulations and apply to all
nondomestic sources introducing pollutants into a POTW whether or not the
source is subject to Categorical Pretreatment Standards.
Second, the General Pretreatment Regulations establish an administrative
mechanism to ensure that National Pretreatment Standards (Prohibited Discharge
Standards and Categorical Pretreatment Standards) are applied and enforced
upon industrial users. Approximately 1,500 POTWs are required to develop a
locally run pretreatment program to ensure that non-domestic users comply with
applicable pretreatment standards and requirements.
Third, and most importantly for the purposes of this guidance manual, the
General Pretreatment Regulations contain provisions relating directly to the
implementation and enforcement of the Categorical Pretreatment Standards.
Reporting requirements, local limits, monitoring or sampling requirements, and
category determination provisions are discussed. POTW representatives should
refer to 40 CFR Part 403 for specific language and requirements where apprp-
priate.
4-1
-------
4.2 CATEGORY DETERMINATION REQUEST
An existing industrial user (IU) or its POTW may request written
certification from EPA or the delegated State specifying whether or not the
industrial user falls within a particular industry category or subcategory and
is subject to a categorical pretreatment standard. Although the deadline for
submitting a category determination request by existing industrial users sub-
ject to the Leather Tanning and Finishing categorical pretreatment standards
has passed, a new industrial user or its POTW may request this certification
for a category determination anytime prior to commencing its discharge.
Section 403.6(a) does not preclude leather tanning and finishing facilities
from changing operations which would in turn automatically change their
subcategorization status. Facilities that are planning to change their
subcategorization status and are unsure which subcategory they will fall into,
should request a written category determination from the Agency as to whether
the facility falls within a particular subcategory prior to commencing
discharges which would fall within that subcategory.* The contents of a
category determination request and procedures for review are presented in
Section 403.6(a) of the General Pretreatment Regulations.
4.3 MONITORING AND REPORTING REQUIREMENTS OF THE GENERAL PRETREATMENT
REGULATIONS
In addition to the requirements contained in the Leather Tanning and
Finishing Categorical Pretreatment Standards, industrial users subject to
these Standards must fulfill the reporting requirements contained in Section
403.12 of the General Pretreatment Regulations. These requirements include
the submission of baseline monitoring reports, compliance schedules, compli-
ance reports (initial and periodic), notices of slug loading, and record-
keeping requirements. Each of these reporting requirements is briefly
summarized below.
4.3.1 Baseline Monitoring Reports
All industrial users subject to Categorical Pretreatment Standards must
submit a baseline monitoring report (BMR) to the Control Authority. The
purpose of the BMR is to provide information to the Control Authority to
*This statement is taken from part of the Settlement Agreement.
4-2
-------
document the industrial user's current compliance status with a Categorical
Pretreatment Standard. The Control Authority is defined as the POTW if it has
an approved pretreatment program, otherwise the BMR will be submitted to the
State (if the State has an approved State Pretreatment Program) or to the EPA
Region. Additional guidance on BMR reporting is available from the EPA
Regional Pretreatment Coordinator.
BMR Due Dates
Section 403.12(b) requires that BMRs be submitted to the Control Auth-
ority within 180 days after the effective date of a Categorical Pretreatment
Standard or 180 days after the final administrative decision made upon a
category determination request [403.6(a)(4)], whichever is later. The due
date for leather tanning and finishing BMRs was July 5, 1983.
BMR Content
A BMR must contain the following information as required by Section
403.12(b).
1. Name and address of the facility, including names of operator(s) and
owner(s).
2. List of all environmental control permits held by or for the
facility.
3. Brief description of the nature, average production rate and SIC code
for each of the operation(s) conducted, including a schematic process
diagram which indicates points of discharge from the regulated
processes to the POTW.
4. Flow measurement information for regulated process streams discharged
to the municipal system. Flow measurements of other wastestreams
will be necessary if application of the combined wastestream formula
is necessary.
5. Identification of the pretreatment standards applicable to each
regulated process and results of measurements of pollutant concen-
trations and/or mass. All samples must be representative of daily
operations and results reported must include values for daily maximum
and average concentration (or mass, where required). Where the flow
of the regulated stream being sampled is less than or equal to
250,000 gallons per day, the industrial user must take three samples
within a two week period. Where the flow of the stream is greater
4-3
-------
than 250,000 gallons per day, the industrial user must take six sam-
ples within a two week.period. If samples cannot be taken immediate-
ly downstream from the regulated process and other wastewaters are
mixed with the regulated process, the industrial user should measure
flows and concentrations of the other wastestreams sufficient to
allow use of the combined wastestream formula.
6. Statement of certification concerning compliance or noncompliance
with the Pretreatment Standards.
7. If not in compliance, a compliance schedule must be submitted with
the BMR that describes the actions the user will take and a timetable
for completing those actions to achieve compliance with the standard.
This compliance schedule must contain specific increments of progress
in the form of dates for the commencement and completion of major
events, however, no increment of the schedule shall exceed 9 months.
Within 14 days of each completion date in the schedule, the indus-
trial user shall submit a progress report to the Control Authority
indicating whether or not it complied with the increment of progress
to be met on such date, and, if not, the date on which it expects to
comply with this increment of progress and the steps being taken to
return to the schedule.
4.3.2 Report on Compliance
Within 90 days after the compliance date for the Leather Tanning and
Finishing Pretreatment Standards or in the case of a New Source following
commencement of the introduction of wastewater into the POTW, any industrial
user subject to the Standards must submit to the Control Authority a "report
on compliance" that states whether or not applicable pretreatment standards
are being met on a consistent basis. The report must indicate the nature and
concentration of all regulated pollutants in the facility's regulated process
wastestreams; the average and maximum daily flows of the regulated streams;
and a statement of whether compliance is consistently being achieved, and if
not, what additional operation and maintenance and/or pretreatment is neces-
sary to achieve compliance. See 40 CFR 403.12(d).
4.3.3 Periodic Reports on Continued Compliance
Unless required more frequently by the Control Authority, all industrial
users subject to the Leather Tanning and Finishing Categorical Pretreatment
Standards must submit a biannual "periodic compliance report" during the
months of June and December. The report shall indicate the precise nature and
4-4
-------
concentrations of the regulated pollutants in its discharge to-the POTW, the
average and maximum daily flow rates of the facility, the methods used by the
indirect discharger to sample and analyze the data, and a certification that
these methods conformed to those methods outlined in the regulations. See 40
CFR '403.12(e).
4.3.4 Notice of Slug Loading
Section 403.12(f) requires industrial users to -notify the POTW imme-
diately of any slug loading of any pollutant, including oxygen demanding
pollutants (BOD, etc.) released to the POTW system at a flow rate and/or
pollutant concentration which will cause interference with the POTW.
4.3.5 Monitoring and Analysis to Demonstrate Continued Compliance
Section 403.12(g) states that the frequency of monitoring to demonstrate
continued compliance shall be prescribed in the applicable Pretreatment Stan-
dard. Since Leather Tanning and Finishing Pretreatment Standards do not
establish any monitoring frequency, the appropriate Control Authority must
establish the monitoring frequency to adequately demonstrate that indirect
*
dischargers subject to these pretreatment standards are in compliance with the
applicable standards. Unless otherwise noted in the appropriate paragraph of
Section 403.12, the monitoring frequency established by the Control Authority
shall be used in the baseline monitoring report (403.12(b)(5)), the report on
compliance with categorical pretreatment standard deadline (403.12(d)), and
the periodic reports on continued compliance (403.12(e)).
Sampling and analysis shall be in accordance with the procedures estab-
lished in 40 CFR Part 136 and any amendments to it or shall be approved by
EPA. When Part 136 techniques are not available or are inappropriate for any
pollutant, then sampling and analysis shall be conducted in accordance with
procedures established by the POTW or using any validated procedure. However,
all procedures for sampling and analysis not included in Part 136 must be
approved by EPA.
4-5
-------
An alternative sulfide analytical method was included in the Leather
Tanning and Finishing regulation based on- a method utilized by the Society of
Leather Trades' Chemists (Method SLM 4/2). The sulfide method (iodometric
titration) promulgated under Section 304(h) of the Act was subject to
interferences, and therefore was not selected as the basis of the regulation.
The outline of this SLM 4/2 method can be found in 40 CFR Part 425.03*,
Leather Tanning and Finishing Category regulations, and is contained in
Appendix B, Part (b).
One of the issues raised by the industry in litigation of the regulations
was that even the SLM 4/2 method, used widely in the industry for chrome
tanning process control, was subject to interferences from highly colored
(e.g., vegetable tanning) wastewaters. In response to this criticism, the
Agency and the industry trade association conducted a cooperative sampling and
analytical method development program. As a result of this cooperative
program, the industry and EPA agreed that the SLM 4/2 is inappropriate for
vegetable tanning facilities. Accordingly, under the Settlement Agreement,
EPA will propose an alternative analytical method (the modified Monier-
Williams Method) f.or facilities with vegetable tanning wastewaters. This
alternative analytical method [see Appendix B, Part (c)] also may be used for
analysis of sulfide in all other wastewaters.
4.3.6 .Compliance Monitoring with Multiple Outfalls
In certain cases where an indirect discharging plant does not combine its
process wastewaters for treatment and discharges through multiple outfalls, a
composite sampling of the multiple outfalls could be accepted. A single
composite sample for multiple outfalls must be comprised of representative
process wastewaters from each outfall. A composite sample must be combined in
proportions determined by the ratio of the process wastewater flow in each
outfall to the total flow of process wastewaters discharged through all
outfalls. Flow measurement for each outfall must be representative of the
plant's operation. An analysis of the total sample would then be compared to
*Will be found in Appendix A to 40 CFR Part 425 of the proposed amendments to
40 CFR 425 implementing the settlement agreement.
4-6
-------
the applicable categorical standard to determine compliance.* If nonprocess
wastewater in combined with process wastewater or if a plant has operations in
more than one subcategory, the plant would have to use the combined waste-
stream formula to make this calculation.
4.3.7 Signatory Requirements for Industrial User Reports
All reports submitted by industrial users (BMR, Initial Report on
Compliance, and Periodic Reports, etc.) must be signed by an authorized
representative in accordance with Section 403.12(k).
4.3.8 Recordkeeping Requirements
Any industrial user subject to the reporting requirements of the General
Pretreatment Regulations shall maintain records of all information resulting
from any monitoring activities required by 403.12 for a minimum of three years
[403.12(n)]. These records shall be available for inspection and copying by
the Control Authority.
4.4 APPLICATION OF THE COMBINED WASTESTREAM FORMULA
One provision of the General Pretreatment Regulations that will often be
used by POTWs and industries to properly monitor and report on compliance with
Categorical Pretreatment Standards, is the Combined Wastestream Formula (CWF)
[40 CFR 403.6(e)]. The CWF is a mechanism for calculating/appropriate
limitations specified in regulations applicable to a wastewater in which
process wastestreams are mixed with regulated, unregulated or dilution
streams, thereby producing a mixed effluent. The CWF is applied to the mixed
effluent to account for the presence of the additional wastestreams.
The following definitions and conditions are important to the proper use
of the CWF.
*This portion of the discussion concerning the multiple outfall requirements
results from the Settlement Agreement.
4-7
-------
Definitions
0 Regulated Process Wastestream - an industrial process waste-
strearn regulated by National Categorical Pretreatment Standards.
° Unregulated Process Wastestream - an industrial process waste-
stream that is not regulated by a categorical standards.
0 Dilute Wastestream - Boiler blowdown, sanitary wastewater, non-
contact cooling water or blowdown, and Paragraph 8 excluded
wastestreams containing none of the regulated pollutant or
only trace amounts of it.
Note- These definitions apply to individual pollutants. A
wastestream from a process may be "regulated" for one pollutant
and "unregulated" for another. In addition, the May 17, 1984
amendment to the CWF allows the Control Authority to exercise
its discretion to determine whether boiler blowdown and noneontact
cooling streams are dilution or unregulated process streams.
° concentration-Based Limit - a limit based on the relative strength
of a pollutant in a wastestream, usually expressed in mg/1
(Ib/gal).
0 Mass-Based Limit - a limitation based on the actual quantity
of a pollutant in a wastestream, usually expressed in kg or Ib
per day.
° Production-Based Limit - a limitation based on the quantity of
a pollutant in a wastestream with respect to production levels,
usually expressed in kg per 1000 kkg of metal processed.
4.4.1 CWF Conditions
To ensure proper application of the CWF, the following conditions
must be met by a municipality and its industries [40 CFR 403.6(e)]:
0 Alternative discharge limits that are calculated in place of a
categorical pretreatment standard must be enforceable as
categorical standard-s.
0 Calculation of alternative limits must be established for all
regulated pollutants in each of the regulated processes.
0 Alternative limits must e established for all regulated pollutants
in each of the regulated processes.
0 Both daily maximum and long-term average (usually monthly)
alternative limits must be calculated for each regulated
pollutant.
0 Alternative limits must be established for all regulated pollutants
in each of the regulated processes.
0 If process changes at an industry warrant, the Control Authority
may recalculate the alternative limits at its discretion or at
4-8
-------
.the request of the industrial user. The new alternative limits
must be calculated.and become effective, within 30 days of the
process change.
0 The Control Authority may impose stricter alternative limits,
but may not impose alternative limits that are less stringent
than the calculated limits.
0 A calculated alternative limit cannot be used if it is below the
analytical detection limit, the IU must either: 1) not combine
some of the dilute streams before they reach the combined
treatment facility, or 2) segregate all was testreams entirely.
4.4.2. Monitoring Requirements for Industrial User Using the CWF
Requirements for self-monitoring by an industrial user are necessary
to ensure compliance with the alternative categorical limit. Because the
Leather Tanning and Finishing pretreatment standards do not include self-
monitoring requirements, the Control Authority will establish appropriate
self-monitoring requirements.
4.4.3. Application of the CWF
The combined wastestream formula are presented in Table 4.1. Table
4.2 presents three examples of how the CWF is used to calculate alternative
limits for specific leather tanning and finishing operations. Before
using the CWF, remember that when two or more regulated wastestreams are
mixed prior to treatment, it is necessary to determine which pretreatment
regulation applies to each regulated wastestream before they are mixed.
For additional information on categorical pretreatment standards and
combined wastestream formula, refer to the manual entitled "Guidance
Manual for the Use of Production-based Pretreatment Standards and the
Combined Wastestream Formula" (September 1985). For calculation of the
total toxic organics (TTO) limits, refer to the manual entitled, "Guidance
Manual for Implementing Total Toxic Organic (TTO) Pretreatment Standards
(September 1985).
4.5 Removal Credits
On April 30, 1986 the United States Court of Appeals for the Third
Circuit upheld the Natural Resources Defense Council's challenge to EPA"s
4-9
-------
TABLE 4.1
COMBINED WASTESTREAM FORMULAS
Alternative Concentration Limit Formula:
N
ct-
N
\
Cf - alternative concentration limit for the pollutant
C, - Categorical Pretreatment Standard concentration limit for the pollutant
1 in regulated stream i
F. - average daily flow (at least 30 day average) of regulated stream i
F. - average daily flow (at least 30 day average) of dilute wastestream(s)
F - average daily flow (at least 30 day average) through the combined
t treatment facility (including regulated, unregulated and dilute
wastestreams) .
N - total number of regulated streams
Alternate Mass Limit Formula
M,. - alternative mass limit for the pollutant
\*
M- - Categorical Pretreatment Standard Production-based limit for the
1 pollutant in regulated stream i
F. - average daily flow (at least 30 day average) of regulated stream i
F. - average daily flow (at least 30 day average) of dilute wastestream(s)
F«. - average daily flow (at least 30 day average) through the combined
treatment facility (including regulated, unregulated and dilute
wastestreams)
N - total number of regulated streams.
4-10
-------
TABLE 4.2
EXAMPLE A
COMBINED WASTESTREAM FORMULA EXAMPLE CALCULATION
WITH CONCENTRATION-BASED LIMITS
Alternative discharge limit for a leather tanning and finishing facility
after November 25, 1985 (compliance date for leather tanning and finishing).
Leather Tanning
and Finishing
(Subcategory 1)
Q = 1.35 mgd
Cr - 12 mg/1
maximum for
any 1 day
- /12 mg/1 (1.35 mgd)
cwf ~ I 1.35
Sanitary
Wastewater
Q = 0.05 mgd
Cr = N/A
1.35 mgd + 0.05 mgd - 0.05 mgd
1.40 mgd
Crcwf = 11'57
maximum for any 1 day
Note: Due to -dilution from sanitary wastewater, the applicable Cr limit, 12
mg/1, is reduced to 11.57 mg/1.
4-11
-------
TABLE 4.2 (Continued)
EXAMPLE B
COMBINED WASTESTREAM FORMULA EXAMPLE
CALCULATION WITH ALTERNATE PRODUCTION-BASED LIMITS
Alternative Mass based discharge limit for a leather tanning and
finishing facility after November 25, 1985 (compliance date for leather
tanning and finishing).
Leather Tanning
and Finishing
(Subcategory 1)
Sanitary
Wastewater
Q = 1.35 mgd
Cr
0.54 lb/1000 Ib
production maximum
for any 1 day
Production = 250,000 Ib/day
of grain leather
Q = 0.05 mgd
W * (TOWTF prod) (* 250-000 "> >r°
Cr fa 135 Ib/day maximum for any 1 day
ri.40 - 0.05
1.35
4-12
-------
TABLE 4.2 (Continued)
EXAMPLE C
COMBINED WASTESTREAM FORMULA EXAMPLE CALCULATION
FOR INTEGRATED (MULTI-SUBCATEGORY) FACILITY
Alternative discharge limit for a multi-subcategory integrated facility
after November 25, 1985 (compliance date for leather and finishing).
Leather Tanning
and Finishing
Subcategory 1 Subcategory 9
Production - 250,000
Ib/day of grain
leather product
Cr^ = 12 mg/1
Q = 1.35 mgd
Sanitary
Wastewater
Product = 100,000 Ib/day
of splits processed
Crg = 19 mg/1
Q = 0.25 mgd
Q = 0.05 mgd
Cr = N/A
Cr
=/12(1.35) + 19(0.25) \ X / 1.65 - 0.05
cwf \1.35 + 0.25 / I 1.65
Cr f = 12.7 mg/1 maximum for any 1 day
Alternate Production-based Limit:
Cr =[(250,000 Ib/day X 0.54 lb/1000 Ib) + (100,000 Ib/day X 0.47 lb/1000 lb)]x
cwf L Subcategory 1 . Subcategory 9 J
1.65 - 0.05
1.60
r = 135 + 47 = 182 Ibs maximum for any 1 day
Crcwf
4-13
-------
removal credits regulation (NRDC vs. EPA, No. 84-3530). The Court struck
down the amended regulation on four separate grounds:
(1) EPA's new definition of a POTW's "consistent removal" rate
failed to implement the requirements of the Clean Water Act and
therefore was invalid;
(2) EPA's failed to justify deletion of the previously promulgated
combined sewer overflow adjustment;
(3) EPA's provision specifying the modification and withdrawal
process of a POTW's removal credits was illegal; and
(4) EPA cannot, in the absence of §4U5 sludge regulations,
authorize the granting of removal credits to POTWs under
§307(b)(l) of the Act.
EPA is determining what course of action to take in light of this
decision. The immediate effect of the court ruling, however, is that no
further consideration can be given to removal credit applications. As
soon as it determines the full scope and effect of this decision
and determines its course of action, EPA will provide guidance through
its Regional Pretreatrnent Coordinators to the POTWs impacted by this
decision. EPA recommends that you periodically contact your Control
Authority or the appropriate EPA Regional Office for any future
guidance on the status of the removal credits regulation
4.6 Fundamentally Different Factors Variance
A request for a fundamentally different factors (PDF) variance is a
mechanism by which a categorical pretreatment standard may be adjusted on
a case-by-case basis. If an indirect discharger, a POTW, or any interested
person believes that the factors relating to a specific indirect discharger
are fundamentally different from those factors considered during development
of the relevant categorical pretreatment standard and that the existence
of those factors justifies a different discharge limit from that specified
in the Categorical Standard, then they may submit a request to EPA for
such a variance (See 40 CFR 403.13).
4-14
-------
4.7 LOCAL LIMITS
Local limits are numerical pollutant concentration or mass-based values
that are developed by a POTW for controlling the discharge of conventional,
non-conventional, or toxic pollutants from indirect sources. They differ from
national categorical pretreatment standards in that categorical pretreatment
standards are developed by EPA and are based on the demonstrated performance
of available pollutant control technologies for specific categorical indus-
tries. These technology-based categorical standards do not consider local
environmental criteria or conditions, but are developed to assure that each
industry within a specified category meets a minimum discharge standard that
is consistent for all POTWs across the United States. Local limits, on the
other hand, are developed to address specific localized impacts on POTWs and
their receiving waters. Local limits are typically designed to protect the
POTW from:
• Introduction of pollutants into the POTW that could interfere with the
operation
t Pass-through of inadequately treated pollutants that could violate a
POTW's NPDES permit or applicable water quality standards
• Contamination of a POTW's sludge, which would limit sludge uses or
disposal practices.
Local limits, as the name implies, take into consideration the factors
that are unique to a POTW, whereas categorical pretreatment standards are
developed only for a general class of industrial dischargers. Local limits
are required under 40 CFR 403.5. For more information on the minimum local
limit requirements for POTWs with approved pretreatment programs and the
relationship between local limits and categorical standards, refer to the
memorandum signed by Rebecca Hanmer on August 5, 1985 entitled-"Local Limit
Requirements for POTW Pretreatment Program".
To assist municipalities in developing defensible and technically sound
numerical effluent limits, EPA has prepared general guidelines on limit
development in its document "Guidance Manual for POTW Pretreatment Program
Development." Appendix L of the manual lists the general methodology,
4-15
'Z
-------
required formulas, and typical environmental criteria used to develop local
limits. The manual is available from EPA Regional offices and delegated
States and should be carefully followed when developing local limits. A more
detailed guidance manual for local limit development is currently under
development. The general methodology includes the following four steps:
Step 1 - Determine the maximum headworks loading (for each specific
pollutant) that will assure that the objectives of the
pretreatment program are met.
Step 2 - Calculate the allowable loading to the POTW by subtracting the
uncontrollable portion of pollutant discharge to the POTW (from
domestic, commercial, and infiltration/inflow sources) from the
total headworks loading value.
Step 3 - Distribute the controllable loading to industrial users through
an allocation process.
Step 4 - Derive specific local limits from the allocation results.
This four-step process must be followed for each pollutant that the POTW
determines may need a specific local limit. As a general rule, the limit
setting analysis should be performed for all pollutants that are discharged to
the POTW in significant quantities. The POTW can identify pollutants of
concern through its industrial waste survey. A procedure for evaluating
industrial waste survey results is included in the EPA guidance manual
mentioned above.
To assist POTWs with the development of local limits, EPA has also
developed a computer program that incorporates the general methodology
required to develop local limits and performs a substantial number of the
calculations required to develop these limits. This computer program has the
following capabilities.
• Performs the four-step limit setting analysis on microcomputer or
mainframe
• Screens input data provided by the POTW
• Supplements POTW data with built-in files containing data on
industrial and municipal wastewater characteristics, POTW removal
rates and POTW inhibition values
4-16
-------
• Allocates-controllable pollutant loads using several different
methodologies
• Compares calculated local limits to EPA categorical standards.
POTWs may obtain information on this computer program by contacting the EPA
Regional office. Instructions are available on how to obtain and use the
computer program as well as how to gain access to a computer system that
supports it.
4-17
r^T*'';';"'i'"Jv t' <'
-------
-------
REFERENCES
Leather Tanning Regulations
Final PSNS Regulations Promulgated
Amended (Promulgated PSES)
Promulgated Revised PSES and PSNS
Corrected and Amended (Typographical
errors and fulfide applicability date)
Amended (Sulfide applicability)
Corrected (Sulfide PSES effective dates)
Corrected (Sulfide PSES effective dates)
Amended (Compliance Date)
Settlement Agreement, dated December 11, 1984
General Pretreatment Regulations
40 CFR Part 403 '
Amended 40 CFR Part 403
Amended 40 CFR Part 403 (Removal Credits)
Amended 40 CFR Part 403 (FDF Provision)
Technical Development Documents
Final Development Document -
Leather Tanning
Guidance Manual for POTW
Pretreatment Program
Development
Procedures Manual for
Reviewing a POTW Pretreatment
Program Submission
Guidance Manual for
Preparation of Removal
Credits Applications
Federal Register Notice
4/9/74 39 FR 12958
3/23/77 42 FR 15696
11/23/82 47 FR 52848
6/30/83 48 FR 30116
7/8/83
7/15/83
8/5/83
9/15/83
1/15/83
4/17/84
8/3/84
9/25/85
EPA Document
No.
48 FR 31404
48 FR 32346
48 FR 35649
48 FR 41410
46 FR 9404
49 FR 21037
49 FR 31212
50 FR 38809
NTIS or GPO
No.
November 1982 440/1-82/016 PB83-172593
October 1983
October 1983
September 1985
R-l
-------
EPA Document NT IS or GPO
Technical Development Documents (Continued) No. - N°_: -
Guidance Manual for
Implementing Total
Toxic Organics (TTO)
Pretreatment Standards September 1985
Guidance Manual for the
Use of Production-based
Pretreatment Standards
and the Combined
Wastestream Formula September 1985
Miscellaneous
RCRA Information for Publicly
Owned Treatment Works September 1985
Local Limits Requirements for POTW Pretreatment Progarms, memorandum signed by
Rebecca Hanmer on August 5, 1985.
Copies of the technical and economic documents may be obtained from
the National .Technical Information Services, Springfield, VA 22161.
(703/487-4650). Pretreatment Program Manuals may be obtained from U.S. EPA,
Permits Division (EN-336), Washington, DC 20460.
R-2
-------
APPENDIX A
EXPANDED REVIEW CRITERIA FOR
LEATHER TANNING SULFIDE WAIVER APPLICATIONS
-------
-------
Introduction
Publicly owned treatment works (POTWs) with industrial users (lUs)
regulated by the 40 CFR 425 Leather Tanning and Finishing Regulations have the
option to request that the categorical pretreatment standard for sulfide be
waived for tanners provided that the user's sulfide discharge does not
interfere with operations of the treatment works. The POTW must provide a
statement that certifies and supports to the Regional Water Division Director
the noninterference claim.
As part of the waiver review process, the Region will determine whether
the applicant has complied with the public noticing and certification
requirements of Sections 425.04(b) and (c). The adequacy of the certification
will be determined by comparing the information in the applicant's submittal
to the criteria as listed below. Section 425.04(b) lists four general
factors on which the POTW must report. Since these factors are general in
nature and tannery sulfide discharges may have significant environmental.
impact, the Region will be using more specific criteria to assess whether this
discharge would have a deleterious effect on the treatment works' operations
If submittals for the waiver requests do not contain sufficient information as
specified by the criteria, the POTWs will be required to provide the Region
with further data for review before a formal determination is issued on the
request.
Criteria
A. Provide the following information for each of the tannery facilities for
which the sulfide waiver is proposed to be granted.
1. Description of tanning operations. .(NOTE: If the user engages in
unhairing operations specify if beamhouse (hair pulp or hair save)
and tanyard (pickling) processes are performed.)
2. The applicable subpart that would apply to the user's operations
according to the Leather Tanning Subcategories.
3. The present, past, and maximum process capacity (hides/day) of the
user.
4. Diagram of tanning and finishing processes and wastewater flows,
especially for unhairing and pickling operations.
A-l
-------
5. Specify whether spent liquors are discharged or recycled.
6. Characteristics of waste discharge including:
a. Analytical data on sulfide and other sulfur compounds such as
sulfates, etc.
b. pH (average and range) of wastestreams. .
c. volume of discharge (average and maximum, GPD).
'?. Specify whether the plant's discharge schedule is continuous, batch,
etc.
8. What, if any, pretreatment is employed at the plant especially in
regards to sulfide and pH?
9. Are the facilities regulated by any local limitations or prohibited
discharges?
- Specify the mechanism (i.e. permits, contract, order, ordinance,
etc.).
10. If the above does apply, have there been any instances where the
discharger did not meet these limitations?
11. Provide a map of the treatment serv.ice area illustrating the points
of discharge of the tanners.
B. The following items .will be considered under factors (l)-(4) of Section
425.04(b).
425.04(b)(l)
"The presence and characteristics, of other industrial wastewaters which
can increase or decrease sulfide concentrations, pH or both."
a. When reporting other industries that have the potential to contribute
to the sulfide or low pH problem specify:
1. The operations of the facility that generate these wastes.
2. Wastewater discharge volume.
3. Wastewater characteristics such as pH and sulfide/sulfur content.
4. Discharge schedule (batch, continuous, etc.).
b. If there are other tanning facilities in the treatment system that
are not requesting the sulfide waiver, indicate whether they have the
potential to contribute to the sulfide or low pH problem. If they do
have this potential, submit information as required in "a" above
about the facilities.
c. On a map of the treatment service area, indicate the location of
industries that do have the potential to contribute to sulfide and pH
problems.
A-2
-------
425.04(b)(2)
"The characteristics of the sewer/ interceptor collection system which
either minimize or enhance opportunities for release of hydrogen sulfide
gas."
a. Is the sewage system free-flowing?
1. Are there stagnant or dead spots in the system after points of
contribution from tanners?
2. Are these areas aerobic or anaerobic?
b. Are personnel that would enter these areas for sampling purposes,
etc., using confined space entry procedures and three-way gas
monitors as precautionary measures?
c. Have there been any reports (not necessarily confirmed) of worker's
health problems that could be related to hydrogen sulfide exposure?
Symptoms could include eye irritation, pulmonary distress, headaches
and dizziness.
d. Have there been complaints of odor problems ("rotten eggs") along the
treatment lines?
e. Provide recent survey information on the sewer lines to illustrate
whether damage has occurred from the conversion of hydrogen sulfide
to sulfuric acid.
425.04(b)(3) .
"The characteristics of the receiving POTW headworks, preliminary and
primary treatment systems, and, sludge holding and dewatering facilities
which either minimize or enhance opportunities for release of hydrogen
sulfide gas." y
a. Are the treatment facilities enclosed or well ventilated?
b. Does the system have a long hydraulic detention time?
c. Does the municipality have an influent/effluent discharge standard
for sulfide or PH? If so, what are they? If not, are any being
proposed? . y
d. Are any of the tanners requesting a waiver for facilities located
within another township or municipality outside your legal
jurisdiction but discharging to your system?
e* ™*, ]eve1s of sulfide are entering and being discharged from the
POTW (average and maximum)?
f. Provide a 5-year historical review of sulfide related interference
problems. This should address corrosion, hydrogen sulfide toxicity
to the system, problems with sludge disposal because of odor, permit
violations and any other POTW interference.
A-3
-------
g. Have there been complaints of odor problems ("rotten eggs") at the
treatment plant?
h Have there been any reports of worker's health problems or deaths
' ?hat could be related to hydrogen sulfide exposure at the treatment
works?
i. Has OSHA established ambient air limits for hydrogen sulfide at the
treatment plant?
425.04 (b)(4) '
"The occurrence of any prior sulfide related interference as defined by
425.02(j)."
Section 425.02(j) defines "Interference" as "the discharge of sulfides in
quantities which can result in human health standards and/or risks to
human life, and an inhibition or disruption of POTW as defined in 40 CFR
403.3(j)."
This definition of interference should be noted when formulating
responses to the above inquiries.
A-4
-------
APPENDIX B
SULFIDE ANALYTICAL METHOD
-------
-------
APPENDIX B
I . SULFIDE ANALYTICAL METHODS
"Sulfide" shall mean total sulfide as measured by the potassium
ferricyanide titration method or the modified Monier-William method described
below.
(a) Applicability
rf P°tass1um ^erricyanide titration method described in §425.03 of 40
425* shall be used whenever practicable for the determination of sulfide
in wastewater discharged, by plants operating in all subcategories except the
r*oc l^e °r pulp> non-chrome tan» retan-wet finish subcategory (Supart C, see
§425.30). In all other cases, the modified Moni en-Williams method as
described in Appendix B to 40 CFR Part 425 in the proposed amendments shall be
used as an alternative to the potassium ferricyanide titration method for the
determination of sulfide in wastewaters discharged by plants operating in all
subcategories except Subpart C.
.The modified Monier-Williams method as described in Appendix B to 40 CFR
Part 425 in the proposed amendments shall be used for the determination of
sulfide in wastewaters discharged by plants operating in the hair save or
pulp, non-chrome tan, retan-wet finish subcategory {Subpart C, see §425.30).
(t>) - Potassium Ferricyanide Titration Method
The potassium ferricyanide titration method is based on method SLM 4/2
ceS°n n ln Off1c1a1 Method of Analysis. Society of Leather Trades' Chemists
Fourth Revised Edition, Redbourn, Herts., England, 1965.
^ (1) Outline of Method. The buffered sulfide solution is titrated with
standard potassium ferricyanide solution in the presence of ferrous
dimethyl.glyoxime ammonia complex. The sulfide is oxidized to sulfur Sulfite
interferes and must be precipitated with barium chloride. Thiosulfate is not
titrated under the conditions of the determination, (Chariot, Ann. chim
anal., 1945, 27, 153; Booth, J^ _Soc. Leather Trades' Chemists, T956,~407 238).
(2) Apparatus. Burrette, 10ml.
(3) Reagents.
(A) Preparation of 0.02N potassium ferricyanide: Weigh to the
nearest tenth of a gram 6.6 g of analytical reagent grade
potassium ferricyanide and dissolve in 1 liter distilled water
Store in an amber bottle in the dark. Prepare fresh each week.'
(B) Standardization of ferricyanide solution: Transfer 50 ml of
solution to a 250 ml Erlenmeyer flask. Add several crystals of
potassium iodide (about 1 g), mix gently to dissolve, add 1 ml
I?UmVln ApP?"d1x A to 40 CFR Part 425 of the proposed amendments
implementing the settlement agreement.
B-l
S%^^
-------
of 6N hydrochloric acid, stopper the flask, and swirl gently.
Let stand for two minutes, add 10 ml of a 30 percent zinc
sulfate solution, and titrate the mixture containing the
gelatinous precipitate with standardized sodium thiosulfate or
phenylarsine oxide titrant in the range of 0.025-0.050N. Add 1
ml of starch indicator'solutions after the color has faded to a
pale yellow, and continue the titration to the disappearance of
the blue color. Calculate the normality of the ferricyanide
solution using the equation:
Normality of Potassium Ferricyanide [K3Fe(CN)6] =
(ml of thiosulfate added) (normality of thiosulfate)
ml of K3Fe(CN)5
(C) Preparation of 6M ammonium chloride buffer, pH 9.3: Dissolve
200 g ammonium chloride in approximately 500 ml distilled
water, add 200ml 14M reagent grade ammonium hydroxide and make
up to 1 liter with distilled water. The buffer should be
prepared in hood. Store in a tightly stoppered container.
(D) Preparation of 0.05M barium chloride solution: Dis
g barium chloride dihydrate in 1 liter of distilled
Dissolve 12-13
water.
(E) Preparation of ferrous dimethylglyoxime indicator solution:
Mix 10 ml 0.6 percent ferrpus sulfate, 50 ml 1 percent
dimethylglyoxime in ethanol, and 0.5 ml concentrated sulfuric
acid.
(F) Preparation of stock sulfide standard, 1000 ppm: Dissolve 2.4
•g reagent grade sodium sulfide in 1 liter of distilled water.
Store in a tightly stoppered container. Diluted working
standards must be prepared fresh daily and their concentrations
determined by EPA test procedure 376.1 immediately prior to
use [see 40 CFR 136.3, Table IB, parameter 66 (49 FR 43234,
October 26, 1984, with correction notice at 50 FR 690, January
4, 1985)].
(G) Preparation of ION NaOH: Dissolve 400 g of analytical reagent
grade NaOH in 1 liter distilled water.
(4) Sample Preservation and Storage.
Samples are to be field filtered (gravity or pressure) with coarse
filter paper (Whatman 4 or equivalent) immediately after collection. Filtered
samples must be preserved by adjustment to pH>12 with ION NaOH. Sample
containers must be covered tightly and stored at 4°C until analysis. Samples
must be analyzed within 48 hours of collection. If these procedures cannot be
achieved, it is the laboratory's responsibility to institute quality control
procedures that will provide documentation of sample integrity.
B-2
-------
(5) Procedure.
(A) Transfer 100 ml .of sample to be analyzed, or a suitable portion
containing not more than 15 mg sulfide supplemented to 100 ml
with distilled water, to a 250 ml Erlenmeyer flask.
(B) Adjust the sample to pH.8.5-9.5 with 6N HC1.
(C) Add 20 ml of 6M ammonium chloride buffer (pH 9.3), 1 ml of
ferrous dimethylglyoxime indicator, and 25 ml of 0.05 M barium
chloride. Mix gently, stopper, and let stand for 10 minutes.
(D) After 10 minutes titrate with standardized potassium
ferricyanide to disappearance of pink color. The endpoint is
reached when there'is no reappearance of the'pink color after
30 seconds.
('6) Calculation and Reporting of Results.
(A) mg/1 Sulfide = A x B x 16.000
vol. in ml of sample titrated
where A = volume in ml of potassium ferricyanide solution used
and B = normality of potassium ferricyanide solution.
(B) Report results to two significant figures.
(7) Quality.Control.
(A) Each laboratory that uses this method is required to operate a
formal quality control program. The minimum requirements of
this program consist of an initial demonstration of laboratory
capability and the analysis of replicate and spiked samples as
a continuing check on performance. The laboratory is required
to maintain performance records to define the quality of data
that is generated. Ongoing performance checks must be compared
with established performance criteria to determine if the
results ,of analyses are within precision and accuracy limits
expected of the methods.
(B) Before performing any analyses, the analyst must demonstrate
the ability to generate acceptable precision and accuracy with
this method by performing the following operations.
(i) Perform four replicate analyses of a 20mg/l sulfide
standard prepared in distilled water [see (3)(F)].
(ii) Calculate clean water precision and accuracy in accordance
with standard statistical procedures. Clean water
acceptance limits are presented below. These criteria
must be met or exceeded before sample analyses can be
initiated. A clean water standard must be analyzed with
each sample set and the established criteria met for the
analysis to be considered under control.
B-3
-------
Clean water precision and accuracy acceptance limits:
For distilled water samples containing from 5 mg/1 to 50
mg/1 sulfide, the mean concentration from four replicate
analyses must be within the range of 50 to 110 percent of
the true value.
(C) The method detection limit (MDL) should be determined
periodically by each participating laboratory in accordance
with the procedures specified in Appendix B to 40 CFR Part 136
(49'FR 4324, October 26, 1984, and correction notice at 50 FR
690, January 4, 1985). The method detection limit (MDL) is
defined as the minimum concentration of a substance that can be
measured and reported with 99 percent confidence that the
analyte concentration is greater than zero and is determined
from analysis of a sample in a given matrix containing the
analyte. This procedure is designed for applicability to a
wide variety of sample types ranging from reagent (blank) water
containing analyte to wastewater containing analyte.
(D) A minimum of one spiked and one duplicate sample must be
performed for each analytical event, or five percent spikes and
five percent duplicates when the number of samples per event
exceeds twenty. Spike levels are to be at the MDL [see (7)(C)]
for MDL samples, and at x where x is the concentration found if
in excess of the MDL. Spike recovery must be 40 to 120 percent
for the analysis of a particular matrix type to be considered
valid. If a sample or matrix type provides performance outside
these acceptance limits, the analyses must be repeated using
the modified Monier-Williams procedure described in Appendix B
to 40 CFR Part 425 in the proposed amendments.
(E) Report results in mg/liter. When duplicate and spiked samples
are analyzed, report all data with the sample results.
(c) Modified Monier-Williams Method.
(1) Outline of Method.
Hydrogen sulfide is liberated from an acidified sample by
distillation and purging with nitrogen gas (N2). Sulfur dioxide interference
is removed by scrubbing the nitrogen gas stream in a pH 7 buffer solution.
The sulfide gas is collected by passage through an alkaline hydrogen peroxide
scrubbing solution in which it is oxidized to sulfate. Sulfate concentration
in the scrubbing solution is determined by either EPA gravimetric test
procedure 375.3 or EPA turbidimetric test procedure 375.4 [see 40 CFR 136.3,
Table IB, parameter 65 (40 FR 43234, October 26, 1984, and correction notice
at 50 FR 690, January 4, 1985)].
(2) Apparatus. (See Figure 1) Catalogue numbers are given only to
provide a more complete description of the equipment necessary, and do not
constitute a manufacturer or vendor endorsement.
B-4
-------
WATER OUT
WATER IN
ADAPTER JOINT
12S ml
3CPARATORY
FUNNEL
INLET
TUBE
IOOO ml
DISTILLING FLASK
ADSORBER HEAD
AND BODY (2)
7
HEATING MANTLE
FIGURE 1
EQUIPMENT ASSEMBLY
B-5
-------
(A) Heating mantle and control (VWR Cat. No. 33752-464)
(B) 1000 ml distilling flask with three 24/40 joints (VWR Cat.
No. 29280-215)
(C) Friedricks condenser with two 24/40 joints (VWR Cat. No.
23161-009)
(D) 125 ml separatory funnel with 24/40 joint (VWR Cat. No.
30357-102)
(E) Inlet tube with 24/40 joint (VWR Cat. No. 33057-105)
(F) Adapter joint 24/40 to 19/38 (VWR Cat. No. 62905-26)
(G) Adsorber head (2 required) (Thomas Cat. No. 9849-R29)
(H) Absorber body (2 required) (Thomas Cat. No. 9849-R32)
(I) Laboratory vacuum pump or water aspirator
(3) Reagents.
(A) Potassium hydroxide, 6N: Dissolve -340 g of analytical
reagent grade KOH in 1 liter distilled water.
(B) Sodium hydroxide, 6N: Dissolve 240 g of analytical
• reagent grade NaOH in 1 liter distilled water.
(C) Sodium hydroxide, 0.03N: Dilute 5.0 ml of 6N NaOH to 1
liter with distilled water.
(D) Hydrochloric acid, 6N: Dilute 500 ml of concentrated HC1
to 1 liter with distilled water.
(E) Potassium phosphate stock buffer, 0.5M: Dissolve 70 g
monobasic potassium phosphate in approximately 800 ml
distilled water. Adjust pH to 7.0 +_ 0.1 with 6N potassium
hydroxide and dilute to 1 liter with distilled water.
Stock solution is stable for several months at 4°C.
(F) Potassium phosphate buffer, 0.05M: Dilute 1 volume of
0.5M potassium phosphate stock buffer with 9 volumes of
distilled water. Solution is stable for 1 month at 4°C.
(G) Alkaline 3 percent hydrogen peroxide. Dilute 1 volume of
30 percent hydrogen peroxide with 9 volumes of 0.03N NaOH.
Prepare this solution fresh each day of use.
(H) Preparation of stock sulfide standard, 1000 ppm: Dissolve
2.4 g reagent grade sodium sulfide in 1 liter of distilled
water. Store in a tightly stoppered container. Diluted
working standards must be prepared fresh daily and their
concentrations determined by EPA test procedure 376.1
B-6
-------
immediately prior to use [see CFR 136.3, Table IB,
parameter 66 (49 FR 43234, October 26, 1984, and
correction notice at 50 FR 690, January 4, 1985)].
(4) Sample Preservation and Storage.
Preserve unfiltered wastewater samples immediately after collection by
adjustment to pH>9 with 6N NaOH and addition of 2 ml of 2N zinc acetate per
liter. This amount of zinc acetate is adequate to preserve 64 mg/1 sulfide
under ideal conditions. Sample containers must be covered tightly and stored
at 4°C until analysis. Samples must be analyzed within seven days of
collection. If these procedures cannot be achieved, it is the laboratory's
responsibility to institute qua!ity control procedures that will provide
documentation of sample integrity.
(5) Procedure. (See Figure 1 for apparatus layout)
(A) Place 50 ml of 0.05M pH 7.0 potassium phosphate buffer in
Trap No. 1.
(B) Place 50 ml of alkaline 3 percent hydrogen peroxide in
Trap No. 2.
(C) Sample introduction and N? prepurge: Gently mix sample to
be analyzed to resuspend settled material, taking care not
to aerate the sample. Transfer 400 ml of sample, or a
suitable portion containing not more than 20 mg sulfide
diluted to 400 ml with distilled water, to the
distillation flask. Adjust the N2 flow so that the
impingers are frothing vigorously but not overflowing.
Vacuum may be applied at the outlet of Trap No. 2 to
assist in smooth purging. The N^ inlet tube of the
distillation flask must be submerged deeply in the sample
to ensure efficient agitation. Purge the sample for 30
minutes without applying heat. Test the apparatus for
leaks during the prepurge cycle (Snoop or soap water
solution).
(D) Volatilization of HyS: Interrupt the N? flow (and vacuum)
and introduce 100 mf of 6N HC1 to the sample using the
separatory funnel. Immediately resume the gas flow (and
vacuum). Apply maximum heat with the heating mantle until
the sample begins to boil, then reduce heat and maintain
gentle boiling and N« flow for 30 minutes. Terminate the
distillation cycle by turning off the heating mantle and
maintaining N« flow through the system for 5 to 10
minutes. Then turn off the N~ flow (and release vacuum)
and cautiously vent the system by placing 50 to 100 ml of
distilled water in the separatory funnel and opening the
stopcock carefully. When the bubbling stops and system is
equalized to atomospheric pressure, remove the separatory
funnel. Extreme care must be excercised in terminating
the distillation cycle to avoid flash-over, draw-back, or
violent steam release.
8-7
~-.~—._,„,,_,-,,._....,
-------
(E) Analysis: Analyze the contents of Trap No. 2 for sulfate
according to either EPA gravimetric test procedure 375.3
or EPA turidimetric test procedure 375.4 [see 40 CFR
136.3, Table IB, parameter 65 (49 FR 43234, October 26,
1984, and correction notice at 50 FR 690, January 4,
1985)]. Use the result to calculate mg/1 in the
wastewater sample.
(6) Calculations and Reporting of Results.
(A) Gravimetric procedure:
mn c,,ifiriP/i - (mg BaSO. collected in Trap No. 2) x (137)
mg suiriue/i Volume in ml of waste sample distilled
(B) Turbidimetric procedure:
1f-H ,, _ _ A x B x 333 _
mg suinae/i - vo]ume in mi Of waste sample distilled
where A = mg/1 of sulfate in trap no. 2
and B = liquid volume in liters in trap no. 2
(C) Report results to two significant figures.
(7) Quality Control .
(A) Each laboratory that uses this method is required to
operate a formal quality control program. The minimum
requirements of this program consist of an initial
demonstration of laboratory capability and the analysis of
replicate and spiked samples as a continuing check on
performance. The laboratory is required to maintain
performance records to define the quality of data that is
generated. Ongoing performance checks must be compared
with established performance criteria to determine if the
results of analyses are within precision and accuracy
limits expected of the method.
(B) Before performing any analyses, the analyst must
demonstrate the ability to generate acceptable accuracy
and precision with this method by performing the following
operations.
(i) Perform four replicate analyses of a 20 mg/1 sulfide
standard prepared in distilled water (see(3)(H)).
(ii) Calculate clean water precision and accuracy in
accordance with standard statistical procedures.
Clean water acceptance limits are presented below.
These criteria must be met or exceeded before sample
analyses can be initiated. A clean water standard
must be analyzed with each sample set and the
B-8
-------
established criteria met for the analysis to be
considered under control.
Clean water precision and accuracy acceptance limits:
For distilled water samples containing from 5 to 50
mg/1 sulfide, the mean concentration from four
replicate analyses must be within the range of 72 to
114 percent of the true value.
(C) The method detection limit (MDL) should be determined
periodically by each participating laboratory in
accordance with the procedures specified in Appendix B to
40 CFR Part 135 (40 FR 4324, October 26, 1984, and
correction notice at 50 FR 69'0, January 4, 1985). The
method detection limit (MDL) is defined as the minimum
concentration of a substance that can be measured and
reported with 99 percent confidence that the analyte
concentration is greater than zero and is determined from
analysis of a sample in a given matrix containing the
analyte. This procedure is designed for applicability to
a wide variety of sample types ranging from reagent
(blank) water containing analyte to wastewater containing
analyte.
(D) A minimum of one spiked and one duplicate sample must be
run with each analytical event, or five percent spikes and
five percent.duplicates when the number of samples per
event exceeds twenty. Spike levels are to be at the MDL
(See Section (7)(C)) for MDL samples, and at x when x is
the concentration found if in excess of the MDL. Spike
recovery must be 60 to 120 percent for the analysis of a
particular matrix type to be considered valid.
(E) Report all results in mg/liter. When duplicate and spike
samples are analyzed, report all data with the sample
results.
B-9
-------
------- |