United States Effluent Guidelines Division EPA-440/1-84/019-5
Environmental Protection WH-552 Jujy 198'
Agency Washington, D.C. 20460
Water and Waste Management
440184019B5 -
&EPA Development Proposed
Document for
Effluent Limitations
Guidelines and
Standards for the
Nonferrous Metals
Point Source Category
Phase II
Supplemental Development
Document For:
Primary Antimony
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DEVELOPMENT DOCUMENT
for
EFFLUENT LIMITATIONS GUIDELINES AND STANDARDS
for the
i
NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY
PHASE II
Primary Antimony Supplement
Jack E. Ravan
Assistant Administrator for Water
Edwin L. Johnson
Director
Office of Water Regulations and Standards
i. ..": r vironrnental Protection Agency
R-.;;.--!!! V, L.brary
230 SJ'!t-i Dearborn Street
Chicago, Illinois 60604
Jeffery D. Denit, Director
Effluent Guidelines Division
Ernst P. Hall, P.E., Chief
Metals and Machinery Branch
James R. Berlow, P.E.
Technical Project Officer
July 1984
U.S. Environmental Protection Agency
Office of Water
Office of Water Regulations and Standards
Effluent Guidelines Division
Washington, D.C. 20460
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PRIMARY ANTIMONY SUBCATEGORY
TABLE OF CONTENTS
Section Page
I SUMMARY AND CONCLUSIONS 1
II RECOMMENDATIONS 3
BPT LIMITATIONS FOR THE PRIMARY ANTIMONY
SUBCATEGORY 3
BAT LIMITATIONS FOR THE PRIMARY ANTIMONY
SUBCATEGORY 4
NSPS FOR THE PRIMARY ANTIMONY SUBCATEGORY. ... 5
PSNS FOR THE PRIMARY ANTIMONY SUBCATEGORY. ... 6
III INDUSTRY PROFILE 9
DESCRIPTION OF PRIMARY ANTIMONY PRODUCTION ... 9
RAW MATERIALS 10
PYROMETALLURGICAL PROCESSES 10
LEACHING 10
AUTOCLAVING 11
ELECTROW INNING 11
CONVERSION TO ANTIMONY TRIOXIDE 11
PROCESS WASTEWATER SOURCES 12
OTHER WASTEWATER SOURCES 12
AGE, PRODUCTION, AND PROCESS PROFILE 12
IV SUBCATEGORIZATION 19
FACTORS CONSIDERED IN SUBCATEGORIZATION 19
FACTORS CONSIDERED IN SUBDIVIDING THE PRIMARY
ANTIMONY SUBCATEGORY 20
OTHER FACTORS 20
PRODUCTION NORMALIZING PARAMETERS. . 21
V WATER USE AND WASTEWATER CHARACTERISTICS .... 23
WASTEWATER FLOW RATES 24
WASTEWATER CHARACTERISTICS DATA 24
DATA COLLECTION PORTFOLIOS 24
FIELD SAMPLING DATA 25
WASTEWATER CHARACTERISTICS AND FLOWS BY
SUBDIVISION 26
SODIUM ANTIMONATE AUTOCLAVE WASTEWATER 26
FOULED ANOLYTE 27
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PRIMARY ANTIMONY SUBCATEGORY
TABLE OF CONTENTS (Continued)
Section Page
VI SELECTION OF POLLUTANT PARAMETERS 31
CONVENTIONAL AND NONCONVENTIONAL POLLUTANT
PARAMETERS 31
CONVENTIONAL POLLUTANT PARAMETERS SELECTED ... 31
TOXIC POLLUTANTS 32
TOXIC POLLUTANTS NEVER DETECTED 32
TOXIC POLLUTANTS SELECTED FOR FURTHER
CONSIDERATION IN ESTABLISHING LIMITATIONS
AND STANDARDS. 35
VII CONTROL AND TREATMENT TECHNOLOGIES 39
CURRENT CONTROL AND TREATMENT PRACTICES 39
SODIUM ANTIMONATE AUTOCLAVE WASTEWATER 39
FOULED ANOLYTE 40
CONTROL AND TREATMENT OPTIONS 40
OPTION A 40
OPTION C . . . . '. 40
VIII . COSTS, ENERGY, AND NONWATER QUALITY ASPECTS. . . 41
TREATMENT OPTIONS FOR EXISTING SOURCES 41
OPTION A 41
OPTION C ........ 41
COST METHODOLOGY 41
NONWATER QUALITY ASPECTS 42
ENERGY REQUIREMENTS 42
SOLID WASTE 42
AIR POLLUTION 43
IX BEST PRACTICABLE CONTROL TECHNOLOGY CURRENTLY
AVAILABLE 45
TECHNICAL APPROACH TO BPT 45
INDUSTRY COST AND POLLUTANT REMOVAL ESTIMATES. . 47
BPT OPTION SELECTION 47
WASTEWATER DISCHARGE RATES 48
SODIUM ANTIMONATE AUTOCLAVE WASTEWATER 48
FOULED ANOLYTE 49
REGULATED POLLUTANT PARAMETERS 49
EFFLUENT LIMITATIONS 49
ii
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PRIMARY ANTIMONY SUBCATEGORY
TABLE OF CONTENTS (Continued)
Section
XI
XII
BEST AVAILABLE TECHNOLOGY ECONOMICALLY
ACHIEVABLE 53
TECHNICAL APPROACH TO BAT 53
OPTION A 54
OPTION C 54
INDUSTRY COST AND POLLUTANT REMOVAL ESTIMATES. . 55
POLLUTANT REMOVAL ESTIMATES 55
COMPLIANCE COSTS 55
BAT OPTION SELECTION 56
WASTEWATER DISCHARGE RATES 56
REGULATED POLLUTANT PARAMATERS 57
EFFLUENT LIMITATIONS 58
NEW SOURCE PERFORMANCE STANDARDS 65
TECHNICAL APPROACH TO NSPS 65
OPTION A 65
OPTION C 66
NSPS OPTION SELECTION 66
REGULATED POLLUTANT PARAMETERS 66
NEW SOURCE PERFORMANCE STANDARDS 66
PRETREATMENT STANDARDS 69
TECHNICAL APPROACH TO PRETREATMENT 69
PRETREATMENT STANDARDS FOR NEW SOURCES 70
OPTION A 70
OPTION C 70
PSNS OPTION SELECTION 70
REGULATED POLLUTANT PARAMETERS 71
PRETREATMENT STANDARDS FOR NEW SOURCES 71
XIII
BEST CONVENTIONAL POLLUTANT CONTROL TECHNOLOGY
75
iii
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PRIMARY ANTIMONY SUBCATEGORY
LIST OF TABLES
Number
Page
III-1 INITIAL OPERATING YEAR (RANGE) SUMMARY OF
PLANTS IN THE PRIMARY ANTIMONY SUBCATEGORY
BY DISCHARGE TYPE 13
III-2 PRODUCTION RANGES FOR THE PRIMARY ANTIMONY
SUBCATEGORY 14
III-3 SUMMARY OF PRIMARY ANTIMONY SUBCATEGORY
PROCESSES AND ASSOCIATED WASTE STREAMS 14
V-1 WATER USE AND DISCHARGE RATE FOR SODIUM
ANTIMONATE AUTOCLAVE WASTEWATER 28
V-2 WATER USE AND DISCHARGE RATE FOR FOULED ANOLYTE. 29
V-3 PRIMARY ANTIMONY SAMPLING DATA FOULED ANOLYTE
AUTOCLAVE DISCHARGE RAW WASTEWATER 30
VI-1 FREQUENCY OF OCCURRENCE OF TOXIC POLLUTANTS
PRIMARY ANTIMONY RAW WASTEWATER 37
VI11-1 COST OF COMPLIANCE FOR THE PRIMARY ANTIMONY
SUBCATEGORY DIRECT DISCHARGERS 44
IX-1 BPT WASTEWATER DISCHARGE RATES FOR THE
PRIMARY ANTIMONY SUBCATEGORY 50
IX-2 BPT MASS LIMITATIONS FOR THE PRIMARY ANTIMONY
SUBCATEGORY 51
X-1 POLLUTANT REMOVAL ESTIMATES FOR DIRECT
DISCHARGERS IN THE PRIMARY ANTIMONY
SUBCATEGORY 59
X-2 COST OF COMPLIANCE FOR THE PRIMARY ANTIMONY
SUBCATEGORY DIRECT DISCHARGERS 60
X-3 BAT WASTEWATER DISCHARGE RATES FOR THE
PRIMARY ANTIMONY SUBCATEGORY 61
X-4 BAT MASS LIMITATIONS FOR THE PRIMARY
ANTIMONY SUBCATEGORY 62
v
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PRIMARY ANTIMONY SUBCATEGORY
LIST OF TABLES (Continued)
Number Page
XI-1 NSPS WASTEWATER DISCHARGE RATES FOR THE
XI-2
XII-1
XII-2
PRIMARY ANTIMONY SUBCATEGORY
NSPS FOR THE PRIMARY ANTIMONY SUBCATEGORY. . . .
PSNS WASTEWATER DISCHARGE RATES FOR THE
PRIMARY ANTIMONY SUBCATEGORY
PSNS FOR THE PRIMARY ANTIMONY SUBCATEGORY. . . .
67
68
72
73
vi
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PRIMARY ANTIMONY SUBCATEGORY
LIST OF FIGURES
Number Page
III-1 PRIMARY ANTIMONY PRODUCTION PROCESS
(PYROMETALLURGICAL) 16
III-2 PRIMARY ANTIMONY PRODUCTION PROCESS
(HYDRO-METALLURGICAL) 17
III-3 GEOGRAPHIC LOCATIONS OF THE PRIMARY ANTIMONY
SUBCATEGORY PLANTS 18
IX-1 BPT TREATMENT SCHEME FOR THE PRIMARY ANTIMONY
SUBCATEGORY 52
X-1 BAT TREATMENT SCHEME FOR OPTION A 63
X-1 BAT TREATMENT SCHEME FOR OPTION C 64
Vll
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viii
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PRIMARY ANTIMONY SUBCATEGORY
SECTION I
SUMMARY AND CONCLUSIONS
Pursuant to Sections 301, 304, 306, 307, and 501 of the Clean
Water Act and the provisions of the Settlement Agreement in
Natural Resources Defense Council v. Train, 8 ERG 2120 (D.D.C.
1976) modified, 12 ERG 1833 (D.D.C. 1979), EPA has collected and
analyzed data for plants in the primary antimony subcategory.
EPA has never proposed or promulgated effluent limitations or
standards for this subcategory. This document and the adminis-
trative record provide the technical basis for proposing effluent
limitations based on best practicable technology (BPT) and best
available technology (BAT) for existing direct dischargers, pre-
treatment standards for new indirect dischargers (PSNS), and
standards of performance for new source direct dischargers
(NSPS).
The primary antimony subcategory is comprised of eight plants.
Of the eight plants, one discharges directly to a river, four
plants achieve zero discharge of process wastewater, and three
plants generate no process wastewater.
EPA first studied the primary antimony subcategory to determine
whether differences in raw materials, final products, manufac-
turing processes, equipment, age and size of plants, or water
usage, required the development of separate effluent limitations
and standards for different segments of the subcategory. This
involved a detailed analysis of wastewater discharge and treated
effluent characteristics, including (1) the sources and volume of
water used, the processes used, and the sources of pollutants and
wastewaters in the plant; and (2) the constituents of waste-
waters, including toxic pollutants. As a result, two subdivi-
sions have been identified for this subcategory that warrant
separate effluent limitations. These include:
Sodium antimonate autoclave wastewater, and
Fouled anolyte.
EPA also identified several distinct control and treatment tech-
nologies (both in-plant and end-of-pipe) applicable to the pri-
mary antimony subcategory. The Agency analyzed both historical
and newly generated data on the performance of these technolo-
gies, including their nonwater quality environmental impacts and
air quality, solid waste generation, and energy requirements.
EPA also studied various flow reduction techniques reported in
the data collection portfolios (dcp) and plant visits.
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Engineering costs were prepared for each of the control and
treatment options considered for the subcategory. These costs
were then used by the Agency to estimate the impact of implement-
ing the various options on the subcategory. For each control and
treatment option that the Agency found to be most effective and
technically feasible in controlling the discharge of pollutants,
we estimated the number of potential closures, number of employ-
ees affected, and impact on price. These results are reported in
a separate document entitled "The Economic Impact Analysis of
Proposed Effluent Limitations Guidelines and Standards for the
Nonferrous Smelting and Refining Industry."
After examining the various treatment technologies, the Agency
has identified BPT to represent the average of the best existing
technology. Metals removal based on chemical precipitation and
sedimentation technology is the basis for the BPT limitations.
To meet the BPT effluent limitations based on this technology,
the primary antimony subcategory is expected to incur an esti-
mated capital cost of $34,200 and an annual cost of $17,300.
For BAT, filtration is added an an effluent polishing step to the
BPT end-of-pipe treatment scheme. To meet the BAT effluent limi-
tations based on this technology, the primary antimony subcate-
gory is estimated to incur a capital cost of $41 ,250 and an
annual cost of $21,183.
NSPS is equivalent to BAT. In selecting NSPS, EPA recognized
that new plants have the opportunity to implement the best and
most efficient manufacturing processes and treatment technology.
As such, the technology basis of BAT has been determined as the
best demonstrated technology.
PSES is not being proposed for this subcategory because there are
no existing indirect dischargers in the primary antimony subcate-
gory. For PSNS, the Agency selected end-of-pipe treatment tech-
nology equivalent to BAT.
The best conventional technology (BCT) replaces BAT for the con-
trol of conventional pollutants. BCT is not being proposed at
this time because the methodology for BCT has not yet been
finalized.
The mass limitations and standards for BPT, BAT, NSPS, and PSNS
are presented in Section II.
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PRIMARY ANTIMONY SUBCATEGORY
SECTION II
RECOMMENDATIONS
1. EPA has divided the primary antimony subcategory into two
subdivisions for the purpose of effluent limitations and
standards. These subdivisions are:
(a) Sodium antimonate autoclave wastewater, and
(b) Fouled anolyte.
2. BPT is proposed based on the performance achievable by the
application of chemical precipitation and sedimentation
technology. The following BPT effluent limitations are
proposed:
BPT LIMITATIONS FOR THE PRIMARY ANTIMONY SUBCATEGORY
(a) Sodium Antimonate Autoclave Wastewater
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of antimony contained in
sodium antimonate product
Antimony 20.360 9.079
Arsenic 14.820 6.596
Lead 2.979 1.419
Mercury 1.773 0.709
Total suspended 290.800 138.300
solids
pH Within the range of 7.5 to 10.0
at all times
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BPT LIMITATIONS FOR THE PRIMARY ANTIMONY SUBCATEGORY
(b) Fouled Anolyte
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of antimony metal produced
by electrowinning
Antimony 20.360 9.079
Arsenic 14.820 6.596
Lead 2.979 1.419
Mercury 1.773 0.709
Total suspended 290.800 138.300
solids
pH Within the range of 7.5 to 10.0
at all times
3. BAT is proposed based on the performance achievable by the
application of chemical precipitation, sedimentation, and
multimedia filtration technology. The following BAT effluent
limitations are proposed:
BAT LIMITATIONS FOR THE PRIMARY ANTIMONY SUBCATEGORY
(a) Sodium Antimonate Autoclave Wastewater
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of antimony contained in
sodium antimonate product
Antimony 13.690 6.100
Arsenic 9.859 4.398
Lead 1.986 0.922
Mercury 1.064 0.426
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BAT LIMITATIONS FOR THE PRIMARY ANTIMONY SUBCATEGORY
(b) Fouled Anolyte
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of antimony metal produced
by electrowinning
Antimony 13.690 6.100
Arsenic - 9.859 4.398
Lead 1.986 0.922
Mercury 1.064 0.426
4. NSPS are proposed based on the performance achievable by the
application of chemical precipitation, sedimentation, and
multimedia filtration technology. The following effluent
standards are proposed for new sources:
NSPS FOR THE PRIMARY ANTIMONY SUBCATEGORY
(a) Sodium Antimonate Autoclave Wastewater
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of antimony contained in
sodium antimonate product
Antimony 13.690 6.100
Arsenic 9.859 4.398
Lead 1.986 0.922
Mercury 1.064 0.426
Total suspended 106.400 85.120
solids
pH Within the range of 7.5 to 10.0
at all times
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NSPS FOR THE PRIMARY ANTIMONY SUBCATEGORY
(b) Fouled Anolyte
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
rag/kg (Ib/million Ibs) of antimony metal produced
by electrowinning
Antimony 13.690 6.100
Arsenic 9.859 4.398
Lead 1.986 0.922
Mercury 1.064 0.426
Total suspended 106.400 85.120
solids
pH Within the range of 7.5 to 10.0
at all times
5. PSES is not being proposed for the primary antimony sub-
category at this time because there are no existing indirect
dischargers in the primary antimony subcategory.
6. PSNS are proposed based on the performance achievable by the
application of chemical precipitation, sedimentation, and
multimedia filtration technology. The following pretreatment
standards are proposed for new sources:
PSNS FOR THE PRIMARY ANTIMONY SUBCATEGORY
(a) Sodium Antimonate Autoclave Wastewater
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of antimony contained in
sodium antimonate product
Antimony 13.690 6.100
Arsenic 9.859 4.398
Lead 1.986 0.922
Mercury 1.064 0.426
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PSNS FOR THE PRIMARY ANTIMONY SUBCATEGORY
(b) Fouled Anolyte
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of antimony metal produced
by electrowinning
Antimony 13.690 6.100
Arsenic 9.859 4.398
Lead 1.986 0.922
Mercury 1.064 0.426
7. EPA is not proposing BCT at this time for the primary
antimony subcategory.
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8
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PRIMARY ANTIMONY SUBCATEGORY
SECTION III
INDUSTRY PROFILE
This section of the primary antimony supplement describes the raw
materials and processes used in producing primary antimony and
presents a profile of the primary antimony plants identified in
this study. For a discussion of the purpose, authority, and
methodology for this study and for a general description of the
nonferrous metals manufacturing category, refer to Section III of
the General Development Document.
Although there are about 112 minerals of antimony, the principal
ore mineral is stibnite, the sulfide of antimony. Antimony also
occurs in other metal ores, including gold-quartz deposits and
copper-lead-zinc deposits. The major use of antimony metal is as
an alloying constituent which increases the strength and inhibits
the corrosion of lead and other metals.
Industrial applications of antimony are primarily as an alloying
agent and include use as a hardener in lead storage batteries,
tank linings, and chemical pumps and pipes. Of the many antimony
compounds available commercially, the most important is antimony
trioxide (Sb203). Antimony trioxide is used for flameproof-
ing plastics, paints, vinyls, fabrics, and chemicals. It is also
used in the ceramics industry to impart hardness and acid
resistance to enamel coverings.
DESCRIPTION OF PRIMARY ANTIMONY PRODUCTION
There are two general types of methods of manufacturing antimony
and its compounds: hydrometallurgical methods and pyrometallurg-
ical methods. Antimony metal is produced from antimony minerals
or ore by smelting. Antimony trioxide is produced from antimony
metal or ore concentrates by roasting or burning. These pyro-
metallurgical processes, practiced at five of the eight antimony
plants identified in this subcategory, generate no process
wastewater.
Hydrometallurgical processing, practiced at the remaining three
antimony plants, can be used to produce antimony metal, antimony
trioxide, and sodium antimonate (NaSb03). Hydrometallurgical
processing can be divided into four distinct stages: leaching,
autoclaving, electrowinning, and conversion to antimony trioxide.
The actual processes used at each plant vary with the type and
purity of the raw materials used as well as with the type of
antimony product manufactured. The primary antimony production
processes, both pyrometallurgical and hydrometallurgical, are
presented in Figures III-1 and III-2 and described below.
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RAW MATERIALS
The principal source of antimony is the sulfide ore mineral
stibnite. Stibnite, the sulfide of antimony together with its
oxidized equivalents, is mined in several countries including
Mexico, China, Peru, Yugoslavia, and Algeria. Virtually all
domestic production of primary antimony metal is a by-product of
the refining of base metal and silver ores. Antimony trioxide is
produced from imported ores, antimony metal, and crude antimony
oxide from South Africa.
PYROMETALLURGICAL PROCESSES
Antimony metal can be produced by smelting antimony minerals or
ore with appropriate fluxes. Metal of 99 percent purity can be
manufactured by this process with no generation of wastewater.
Antimony trioxide can be produced by burning or roasting ore con-
centrates or antimony metal. Burning converts the sulfide ore to
volatile antimony trioxide. Evaporation separates the slag from
the trioxide which two plants reported is collected in a baghouse
and packaged for sale. One plant practices wet air pollution
control to recover antimony from the gases leaving the baghouse.
Because the scrubber liquor from this product recovery step is
completely recycled in order to recovery antimony, the final
emissions scrubber is-not considered to be a wastewater source in
this subcategory. No plants in this subcategory reported sulfur
dioxide (S02) emissions from the trioxide production process.
LEACHING
A variety of antimony compounds can be produced from ore concen-
trates by hydrometallurgical processes. Leaching of the concen-
trate is conducted batchwise in a heated, pressurized vat. Some
concentrates are blended with coke, sodium sulfate, and sodium
carbonate and melted in a furnace before leaching with sodium
hydroxide. Other concentrates are combined with sodium sulfide
and sulfur and leached with sodium hydroxide without prior
melting. In either case, the leaching process produces soluble
Na3SbS3 and Na3AsS3« Because of the coke used as a raw
material in the furnace, EPA is considering the possibility that
several organic pollutants are present in the wastewater
Solids are separated from the leaching solution by thickening and
filtration. The residue, which contains compounds such as
pyrite, silica, stibnite, soluble arsenic, and NaAsS3, is
either disposed of or further processed to recover other mecals.
Antimony is recovered from the leaching solution either by auto-
claving or by electrowinning, depending on the product desired.
10
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AUTOCIAVING
Sodium antimonate (NaSb03> is produced by autoclaving the
antimony-bearing solution from the leaching process with oxygen.
Autoclaving consists of heating the solution under pressure in
the presence of oxygen. The elevated temperature and pressure
drive the oxidation reaction resulting in the formation of
insoluble sodium antimonate which is separated from the remaining
liquid. After drying, the product is packaged and sold. The
autoclave discharge is the only wastewater generated by this
process.
ELECTROWINNING
Antimony metal is recovered from the pregnant solution from the
leaching process by electrowinning. Antimony is deposited on the
cathode as a brittle, non-adherent layer which is periodically
stripped and washed. It is then either sold or further processed
to antimony trioxide. The wash water is not discharged.
Because the products of oxidation at the anode interfere with the
deposition of antimony at the cathode, two different and physi-
cally separated solutions are used. The catholyte, which in this
case is the pregnant solution from the leaching process, sur-
rounds the cathode and the anolyte surrounds the anode. Inter-
mingling of the two solutions is minimized by a canvas barrier.
Small pores in the canvas allow the solutions to contact; this
maintains the integrity of the electrical circuit and permits
current to flow.
After the antimony has been removed, the barren catholyte is
recycled to the process using one of two methods. At the plant
which reports melting of the ore before leaching, spent electro-
lyte is spray dried. The dried salts are captured in a baghouse
and recycled to the blending step. At the two plants which leach
concentrates without first melting them, barren catholyte solu-
tion is recycled directly to the leaching process. One of those
two plants removes the fouled anolyte and treats it by autoclav-
ing to recover sodium antimonate for recycle to the leaching pro-
cess. The fouled anolyte discharge is the only wastewater gener-
ated by the electrowinning process. The subsequent autoclaving
of this stream is considered to be a preliminary wastewater
treatment process and is distinguished from autoclaving to
produce sodium antimonate as a final product.
CONVERSION TO ANTIMONY TRIOXIDE
Antimony metal produced by electrowinning or purchased antimony
metal can be converted to antimony trioxide in a fuming furnace.
The product of this process is captured in a baghouse and sold.
There is no generation of wastewater during this conversion
process.
11
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PROCESS WASTEWATER SOURCES
Although a variety of processes are involved in primary antimony
production, the process wastewater sources can be subdivided as
follows:
1. Sodium antimonate autoclave wastewater, and
2. Fouled anolyte.
OTHER WASTEWATER SOURCES
There are other waste streams associated with the primary anti-
mony subcategory. These waste streams include, but are not
limited to:
1. Stormwater runoff, and
2. Maintenance and cleanup water.
These waste streams are not considered as a part of this rulemak-
ing. EPA believes that the flows and pollutant loadings associ-
ated with these waste streams are insignificant relative to the
waste streams selected, or are best handled by the appropriate
permit authority on a case-by-case basis under authority of
Section 403 of the Clean Water Act.
AGE, PRODUCTION, AND PROCESS PROFILE
Figure II1-3 shows the location of the eight primary antimony
plants operating in the United States. The plants are geograph-
ically scattered, located in seven states across the country.
Table II1-1 shows the relative age and discharge status of the
antimony plants. The oldest plant was built in the 1880's, and
three others are more than 30 years old. Two new plants have
been built within the last 10 years. From Table III-2, it can be
seen that six of the seven plants that provided production infor-
mation produced less than 300 kkg/yr of antimony and antimony
compounds. The one remaining plant produced more than 2,000
kkg/yr of antimony in the form of antimony trioxide.
Table III-3 provides a summary of the number of plants using
specific manufacturing processes and the number of plants gener-
ating wastewater for the streams associated with those processes.
12
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Table III-3
SUMMARY OF PRIMARY ANTIMONY SUBCATEGORY PROCESSES
AND ASSOCIATED WASTE STREAMS
Process or Waste Stream
Pyrometallurgical processes
Leaching
Autoclaving
Sodium antimonate autoclave
wastewater
Electrowinning
Fouled anolyte
Conversion to antimony trioxide
Number of
Plants With
Process or
Waste Stream
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*Through reuse or evaporation practices, a plant may "generate" a
wastewater from a particular process but not discharge it.
15
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PRIMARY ANTIMONY SUBCATEGORY
SECTION IV
SUBCATEGORIZATION
As discussed in Section IV of the General Development Document,
the nonferrous metals manufacturing category has been subcatego-
rized to take into account pertinent industry characteristics,
manufacturing process variations, and a number of other factors
which affect the ability of the facilities to achieve effluent
limitations. This section summarizes the factors considered
during the designation of the primary antimony subcategory and
its related subdivisions. Production normalizing parameters for
each subdivision will also be discussed.
FACTORS CONSIDERED IN SUBCATEGORIZATION
The following factors were evaluated for use in subcategorizing
the nonferrous metals manufacturing category:
1 . Metal products, co-products, and by-products;
2* Raw materials;
3. Manufacturing processes;
4. Product form;
5. Plant location;
6. Plant age;
7. Plant size;
8. Air pollution control methods;
9. Meteorological conditions;
10. Treatment costs;
11. Nonwater quality aspects;
12. Number of employees;
13. Total energy requirements; and
14. Unique plant characteristics.
Evaluation of all factors that could warrant subcategorization
resulted in the designation of the primary antimony subcategory.
Three factors were particularly important in establishing these
classifications: the type of metal produced, the nature of the
raw material used, and the manufacturing processes involved.
In Section IV of the General Development Document, each of these
factors is described, and the rationale for selecting metal prod-
uct, manufacturing process, and raw materials as the principal
factors used for subcategorization is discussed. On this basis,
the nonferrous metals manufacturing category (phase II) was
divided into 21 subcategories, one of them being primary
antimony.
19
-------
FACTORS CONSIDERED IN SUBDIVIDING THE PRIMARY ANTIMONY SUB-
(JATEGUK?
The factors listed previously were each evaluated when consider-
ing subdivision of the primary antimony subcategory. In the
discussion that follows, the factors will be described as they
pertain to this particular subcategory.
The rationale for considering further subdivision of the primary
antimony subcategory is based primarily on differences in the
producton processes and raw materials used. Within this subcate-
gory, a number of different operations are performed, which may
or may not have a water use or discharge, and which may require
the establishment of separate effluent limitations. While pri-
mary antimony is still considered a single subcategory, a more
thorough examination of the production processes has illustrated
the need for limitations and standards based on a specific set of
waste streams. Limitations will be based on specific flow
allowances for the following subdivisions:
1. Sodium antimonate autoclave wastewater, and
2. Fouled anolyte.
These subdivisions represent the only reported sources of waste-
water in this subcategory and follow directly from differerces in
the production stages of primary antimony.
The plant which manufactures sodium antimonate autoclaves the
antimony bearing solution from the leaching process. The first
subdivision is associated with the wastewater discharged from
this autoclaving operation.
When fouled anolyte is removed from the electrowinning operation
and autoclaved for sodium antimonate recovery, a wastewater
stream is produced at one plant. Other plants recycle the elec-
trolyte with no reported wastewater discharge. Thus, the second
subdivision accounts for operational differences in the electro-
winning stage of antimony production.
OTHER FACTORS
The other factors considered in this evaluation either support
the establishment of the two subdivisions or were shown to be
inappropriate bases for subdivision. Air pollution control
methods, treatment costs, and total energy requirements are
functions of the selected subcategorization factors, namely metal
product, raw materials, and production processes. Therefore,
they are not independent factors and do not affect the subcatego-
rization which has been applied. As discussed in Section IV of
the General Development Document, certain other factors, such as
20
-------
plant age, plant size, and the number of employees, were also
evaluated and determined to be inappropriate for use as bases for
subdivision of nonferrous metals plants.
PRODUCTION NORMALIZING PARAMETERS
As discussed previously, the effluent limitations and standards
developed in this document establish mass limitations on the dis-
charge of specific pollutant parameters. To allow these regula-
tions to be applied to plants with various production capacities,
the mass of pollutant discharged must be related to a unit of
production. This factor is known as the production normalizing
parameter (PNP).
In general, for each production process which has a wastewater
associated with it, the mass of antimony contained in the product
will be used as the PNP. Thus, the PNPs for the two subdivisions
are as follows:
Subdivision PNP
1. Sodium antimonate autoclave antimony contained in sodium
wastewater antimonate product
2. Fouled anolyte antimony metal produced by
electrowinning
21
-------
PRIMARY ANTIMONY SUBCATEGORY
SECTION V
WATER USE AND WASTEWATER CHARACTERISTICS
This section describes the characteristics of the wastewaters
associated with the primary antimony subcategory. Water use and
discharge rates are explained and then summarized in tables at
the end of this section. Data used to characterize the waste-
waters are presented. Finally, the specific source, water use
and discharge flows, and wastewater characteristics for each
separate wastewater source are discussed.
Section V of the General Development Document contains a detailed
description of the data sources and methods of analysis used to
characterize wastewater from the nonferrous metals manufacturing
category. To summarize this information briefly, two principal
data sources were used: data collection portfolios (dcp) and
field sampling results. Data collection portfolios contain
information regarding wastewater flows and production levels.
In order to conduct an analysis of the primary antimony subcate-
gory waste streams and quantify the pollutant discharge from
plants in this subcategory, the levels of toxic pollutants in the
wastewaters must be known. Although data were not obtained by
sampling a primary antimony plant, one plant submitted sampling
data of their wastewater in the dcp. The data consist of analy-
ses for two classes of pollutants: toxic metal pollutants, and
conventional pollutants. Samples were not analyzed for toxic
organic pollutants because there was no reason to believe that
organic pollutants would be present in wastewaters generated by
the primary antimony subcategory. (Because the analytical stan-
dard for TCDD was judged to be too hazardous to be made generally
available, samples were never analyzed for this pollutant.
Samples were also not analyzed for asbestos or cyanide. There is
no reason to expect that TCDD, asbestos, or cyanide would be
present in primary antimony wastewater.)
As described in Section- IV of this supplement, the primary anti-
mony subcategory has been split into two subdivisions or waste-
water sources, so that the proposed regulation contains mass
discharge limitations and standards for two unit processes
discharging process wastewater. Differences in the wastewater
characteristics associated with these subdivisions are to be
expected. For this reason, wastewater streams corresponding to
each subdivision are addressed separately in the discussions that
follow. These wastewater sources are:
1. Sodium antimonate autoclave wastewater, and
2. Fouled anolyte.
23
-------
WASTEWATER FLOW RATES
Data supplied by dcp responses were evaluated, and two flow-to-
production ratios, water use and wastewater discharge flow, were
calculated for each stream. The two ratios are differentiated by
the flow value used in calculation. Water use is defined as the
volume of water or other fluid required for a given process per
mass of antimony produced and is therefore based on the sum of
recycle and makeup flows to a given process. Wastewater flow
discharged after pretreatment or recycle (if these are present)
is used in calculating the production normalized flowthe volume
of wastewater discharged from a given process to further treat-
ment, disposal, or discharge per mass of antimony produced. Dif-
ferences between the water use and wastewater flows associated
with a given stream result from recycle, evaporation, and carry-
over on the product. The production values used in calculation
correspond to the production normalizing parameter, PNP, assigned
to each stream, as outlined in Section IV. As an example, sodium
antimonate autoclave wastewater is related to the production of
antimony contained in the sodium antimonate product. As such,
the discharge rate is expressed in liters of autoclave wastewater
per metric ton of antimony contained in the sodium antimonate
product (gallons of wastewater per ton of antimony contained in
the sodium antimonate product).
The production normalized discharge flows were compiled by stream
type. These production normalized water use and discharge flows
are presented by subdivision in Tables V-1 and V-2 at the end of
this section. Where appropriate, an attempt was made to identify
factors that could account for variations in water use and dis-
charge rates. These variations are discussed later in this sec-
tion by subdivision. A similar analysis of factors affecting the
wastewater flows is presented in Sections X, XI, and XII where
representative BAT, NSPS, and pretreatment flows are selected for
use in calculating the effluent limitations.
The water use and discharge rates shown do not include nonprocess
wastewater, such as rainfall runoff and noncontact cooling water.
WASTEWATER CHARACTERISTICS DATA
Data used to characterize the various wastewaters associated with
primary antimony production come from two sources: data collec-
tion portfolios and analytical data from field sampling.
DATA COLLECTION PORTFOLIOS
In the data collection portfolios, the antimony plants that gen-
erate wastewater were asked to specify the presence of toxic pol-
lutants in their wastewater. Of the five primary antimony plants
24
-------
that generate wastewater, three responded to this portion of the
questionnaire. No plant responding to the questionnaire reported
the presence of any toxic organic pollutants. The responses for
the toxic metals and cyanide are summarized below.
Pollutant
Known Present
Antimony 2
Arsenic 2
Beryllium 0
Cadmium 1
Chromium 0
Copper 0
Cyanide 0
Lead 1
Mercury 1
Nickel 0
Selenium 1
Silver 0
Thallium 1
Zinc 1
FIELD SAMPLING DATA
Believed Present
(Based on'Raw Materials and
Process Chemicals Used)
0
1
0
0
0
0
0
0
0
0
0
0
0
0
Sampling data for the primary antimony subcategory were provided
by one company in its dcp. No other field sampling programs were
conducted.
Raw wastewater data are summarized in Table V-3 at the end of
this section. Analytical results for eight samples of the fouled
anolyte autoclave discharge were provided in one dcp. The data
included results for several toxic metals and two conventional
pollutant parameters. No toxic organic, cyanide or source water
data were provided.
Several points regarding the data tables should be noted. First,
Table V-3 includes some samples measured at concentrations con-
sidered not quantifiable. The detection limits shown on the data
tables are not the same in all cases as the published detection
limits for these pollutants by the same analytical methods. The
detection limits used were reported with the analytical data and
hence are the appropriate limits to apply to the data. Detection
limit variation can occur as a result of a number of laboratory-
specific, equipment-specific, and daily operator-specific
factors. These factors can include day-to-day differences in
machine calibration, variation in stock solutions, and variation
in operators.
25
-------
Second, the analysis of data includes some samples measured at
concentrations considered not quantifiable. If a pollutant is
reported as not detected, a value of zero is used in calculating
the average. Toxic metal values reported as less than a certain
value are considered as not quantifiable and a value of zero is
used in the calculation of the average.
WASTEWATER CHARACTERISTICS AND FLOWS BY SUBDIVISION
Since primary antimony production involves two principal sources
of wastewater and each has potentially different characteristics
and flows, the wastewater characteristics and discharge -rates
corresponding to each subdivision will be described separately.
A brief description of why the associated production processes
generate a wastewater and explanations for variations of water
use within each subdivision will also be discussed.
SODIUM ANTIMONATE AUTOCLAVE WASTEWATER
Sodium antimonate (NaSb03) is produced by autoclaving the
antimony-bearing solution from the leaching process with oxygen.
The autoclave wastewater is discharged. The production normal-
ized water use and discharge rates for sodium antimonate auto-
clave wastewater are given in Table V-1 in liters per metric ton
of antimony contained in sodium antimonate product.
The one company which reports this wastewater stream did not pro-
vide flow rate information. It is assumed that the amount of
wastewater generated by autoclaving the leaching solution is the
same as the amount of wastewater generated by electrowinning a
solution containing the same amount of antimony. Therefore, the
production normalized discharge flow for sodium antimonate
autoclave discharge water is assumed to be equal to that for the
fouled anolyte using the antimony content of the product as the
production normalizing parameter.
No sampling data are available for this stream, but it is
expected to be similar in composition to the fouled anolyte auto-
clave discharge for which data are present in Table V-3. The
fouled anolyte wastewater is essentially the same as the sodium
antimonate autoclave wastewater except that the influent to the
fouled anolyte autoclave has had much of the antimony removed.
The sodium antimonate autoclave wastewater is therefore expected
to contain treatable concentrations of suspended solids and toxic
metals, including antimony, arsenic, and mercury. Also, EPA is
Considering the possibility that toxic organic pollutants are
present in the wastewater, because of the coke used as a raw
material in the smelting furnace.
26
-------
FOULED ANOLYTE
Antimony metal is produced by electrowinning the pregnant solu-
tion from the leaching process. Barren electrowinning solution
is recycled to the process by various means at three plants. One
of those plants removes a portion of the barren electrolyte,
referred to as the fouled anolyte, and treats it by autoclaving
with oxygen to recover sodium antimonate. The production normal-
ized water use and discharge rates for the fouled anolyte are
given in Table V-2 in liters per metric ton of antimony metal
produced by electrowinning.
No sampling data are available for this stream, but it is
expected to be similar in composition to the fouled anolyte
autoclave discharge for which data are presented in Table V-3.
Autoclaving is used as a treatment process to remove antimony as
sodium antimonate from the fouled anolyte, but it is not expected
to greatly affect other components of the wastewater. The fouled
anolyte stream is therefore expected to be characterized by
treatable concentrations of suspended solids and toxic metals,
including antimony, arsenic, and mercury. Also, EPA is con-
sidering the possibility that toxic organic pollutants are
present in the wastewater, because of the coke used as a raw
material in the smelting furnace.
27
-------
Table V-1
WATER USE AND DISCHARGE RATE FOR
SODIUM ANTIMONATE AUTOCLAVE WASTEWATER
(1/kkg of antimony contained in sodium antimonate product)
Production
Production Normalized
Percent Normalized Discharge
Plant Code Recycle Water Use Flow
1157 NR NR 7,093*
NR = Data not reported in dcp.
*Assumed value (see Text).
28
-------
Table V-2
WATER USE AND DISCHARGE RATE FOR
FOULED ANOLYTE
(1/kkg of antimony metal produced by electrowinning)
Production
Production Normalized
Percent Normalized Discharge
Plant Code Recycle Water Use Flow
1159 NR NR 7,093
NR = Data net reported in dcp.
29
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PRIMARY ANTIMONY SUBCATEGORY
SECTION VI
SELECTION OF POLLUTANT PARAMETERS
Section V of this supplement presented data from primary antimony
sampling analyses. This section examines that data and discusses
the selection or exclusion of pollutants for potential limita-
tion.
Each pollutant selected for potential limitation is discussed in
Section VI of the General Development Document. That discussion
provides information concerning the nature of the pollutant
(i.e., whether it is a naturally occurring substance, processed
metal, or a manufactured compound); general physical properties
and the form of the pollutant; toxic effects of the pollutant in
humans and other animals; and behavior of the pollutant in POTW
at the concentrations expected in industrial discharges.
The discussion that follows presents and briefly discusses the
selection of conventional pollutants and pollutant parameters for
effluent limitations. Also described is the analysis that was
performed to select or exclude toxic pollutants for further
consideration for limitations and standards. Pollutants will be
considered for limitation if they are present in concentrations
treatable by the technologies considered in this analysis. The
treatable concentrations used for the toxic metals were the long-
term performance values achievable by chemical precipitation,
sedimentation, and filtration. The treatable concentrations used
for the toxic organics were the long-term performance values
achievable by carbon adsorption (see Section VII of the General
Development Document - Combined Metals Data Base).
CONVENTIONAL AND NONCONVENTIONAL POLLUTANT PARAMETERS
This study examined samples from the primary antimony subcategory
for two conventional pollutant parameters (total suspended solids
and pH).
CONVENTIONAL POLLUTANT PARAMETERS SELECTED
The conventional pollutants or pollutant parameters selected for
limitation in this subcategory are:
total suspended solids (TSS)
pH
31
-------
Nonconventional pollutant parameters were not selected for
limitation in this subcategory.
TSS concentrations ranging from 348 to 1 ,256 mg/1 were observed
in the five raw waste samples analyzed for TSS in this study.
All five concentrations were well above the 2.6 mg/1 treatability
concentration. Most of the specific methods used to remove toxic
metals from a wastewater do so by converting them to precipi-
tates. Meeting a limit on total suspended solids ensures that
removal of these precipitated toxic metals has been effective.
For this reason, total suspended solids are selected for
limitation in this subcategory.
The'eight pH values observed during this study ranged from 12.85
to 13.40, all outs\de the 7.5 to 10.0 range considered desirable
for discharge to receiving waters. Effective removal of toxic
metals by chemical precipitation requires careful control of pH.
Therefore, pH is selected for limitation in this subcategory.
TOXIC POLLUTANTS
The frequency of occurrence of the toxic pollutants in the raw
wastewater samples is presented in Table VI-1. Table VI-1 is
based on the raw wastewater data provided for the fouled anolyte
autoclave discharge (see Section V). These data provide the
basis for the categorization of specific pollutants, as discussed
below.
TOXIC POLLUTANTS NEVER DETECTED
The toxic pollutants listed below were not detected in any raw
wastewater samples from this subcategory. Therefore, they are
not selected for consideration in establishing limitations.
1. acenaphthene*
2. acrolein*
3. acrylonitrile*
4. benzene*
5. benzidine*
6. carbon tetrachloride (tetrachloromethane)*
7. chlorobenzene*
8. 1,2,4-trichlorobenzene*
9. hexachlorobenzene*
10. 1,2-dichloroethane*
11. 1,1 ,1-trichloroethane*
12. hexachloroethane*
13. 1,1-dichloroethane*
14. 1,1,2-trichloroethane*
15. 1,1,2,2-tetrachloroethane*
16. chloroethane*
32
-------
17. bis (chloromethyl) ether (DELETED)*
18. bis (2-chloroethyl) ether*
19. 2-chloroethyl vinyl ether (mixed)*
20. 2-chloronaphthalene*
21. 2,4,6-trichlorophenol*
22. parachlorometa cresol*
23. chloroform (trichlorpmethane)*
24. 2-chlorophenol*
25. 1,2-dichlorobenzene*
26. 1 ,3-dichlorobenzene*
27. 1,4-dichlorobenzene*
28. 3,3'-dichlorobenzidine*
29. 1 ,1-dichloroethylene*
30. 1,2-trans-dichloroethylene*
31. 2,4-d ichlorophenol*
32. 1 ,2-dichloropropane*
33. 1,2-dichloropropylene (1,3-dichloropropene)*
34. 2,4-dimethylphenol*
35. 2,4-dinitrotoluene*
36. 2,6-dinitrotoluene*
37. 1,2-diphenylhydrazine*
38. ethylbenzene*
3 9. fluoranthene*
40. 4-chlorophenyl phenyl ether*
41. 4-bromophenyl phenyl ether*
42. bis (2-chloroisopropyl) ether*
43. bis (2-choroethoxy) methane*
44. methylene chloride (dichloromethane)*
45. methyl chloride (chloromethane)*
46. methyl bromide (bromomethane)*
47. bromoform (tribromomethane)*
48. dichlorobromomethane*
49. trichlorofluoromethane (DELETED)*
50. dichlorofluoromethane (DELETED)*
51. chlorodibromomethane*
52. hexachlorobutadiene*
53. hexachlorocyclopentadiene*
54. isophorone*
55. naphthalene*
56. nitrobenzene*
57. 2-nitrophenol*
58. 4-nitrophenol*
59. 2,4-dinitrophenol*
60. 4,6-dinitro-o-cresol*
61. N-nitrosodimethylamine*
62. N-nitrosodiphenylamine*
63. N-nitrosodi-n-propylamine*
64. pentachlorophenol*
65. phenol*
66. bis(2-ethylhexyl) phthalate*
33
-------
67. butyl benzyl phthalate*
68. di-n-butyl phthalate*
69. di-n-octyl phthalate*
70. diethyl phthalate*
71. dimethyl phthalate*
72. benzo (a)anthracene (1,2-benzanthracene)*
73. benzo (a)pyrene (3,4-benzopyrene)*
74. 3,4-benzofluoranthene*
75. benzo(k)fluoranthane (11,12-benzofluoranthene)*
76. chrysene*
77. acenaphthylene*
78. anthracene*
79. benzo(ghi)perylene (1,11-benzoperylene)*
80. fluorene*
81. phenanthrene*
82. dibenzo (a,h)anthracene (1,2,5,6-dibenzanthracene)*
83. indeno (1,2,3-cd)pyrene (w,e,-o-phenylenepyrene)*
84. pyrene*
85. tetrachloroethylene*
86. toluene*
87. trichloroethylene*
88. vinyl chloride (chloroethylene)*
89. aldrin*
90. dieldrin*
91. chlordane (technical mixture and metabolites)*
92. 4, 4'-DDT*
93. 4,4'-DDE(p,p'DDX)*
94. 4,4'-DDD(p,p'TDE)*
95. Alpha-endosulfan*
96. Beta-endosulfan*
97. endosulfan sulfate*
98. endrin*
99. endrin aldehyde*
100. heptachlor*
101. heptachlor epoxide*
102. Alpha-BHC*
103. Beta-BHC*
104. Gamma-BHC (lindane)*
105. Delta-BHC*
106. PCB-1242 (Arochlor 1242)*
107. PGB-1254 (Arochlor 1254)*
108. PCB-1221 (Arochlor 1221)*
109. PCB-1232 (Arochlor 1232)*
110. PCB-1248 (Arochlor 1248)*
111. PCB-1260 (Arochlor 1260)*
112. PCB-1016 (Arochlor 1016)*
113. toxaphene*
116. asbestos (Fibrous)
11 7. beryllium*
119. chromium (Total)*
34
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121. cyanide (Total)*
124. nickel*
125. selenium*
126. silver*
127. thallium*
129. 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)
*We did not analyze for these pollutants in samples of raw
wastewater from this subcategory. These pollutants are not
believed to be present based on the Agency's best engineering
judgement which includes consideration of raw materials and
process operations.
TOXIC POLLUTANTS SELECTED FOR FURTHER CONSIDERATION IN ESTABLISH-
ING LIMITATIONS AND STANDARDS
The toxic pollutants listed below are selected for further con-
sideration in establishing limitations and standards for this
subcategory. The toxic pollutants selected for further consider-
ation for limitation are each discussed following the list.
114. antimony
115. arsenic
118. cadmium
120. copper
122. lead
123. mercury
128. zinc
Antimony was found in eight samples at concentrations ranging
from 3.7 to 120 mg/1. All eight concentrations were above the
0.47 mg/1 concentration considered achievable by identified
treatment technology. Therefore, antimony is selected for fur-
ther consideration for limitation in this subcategory.
Arsenic was detected in eight samples at concentrations ranging
from 260 to 3,700 mg/1. All eight concentrations were above the
0.34 mg/1 treatability concentration. Therefore, arsenic is
selected for further consideration for limitation.
Cadmium was detected in quantifiable concentrations in two of
eight samples (0.21 and 0.30 mg/1). Both of these samples were
above the 0.049 mg/1 treatability concentration. Therefore,
cadmium is selected for further consideration for limitation.
Copper was detected in eight samples at concentrations ranging
from 0.20 to 0.8 mg/1. Three of those samples were above the
0.39 mg/1 treatability concentration. Therefore, copper is
selected for further consideration for limitation.
35
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Lead was found in one of eight samples above quantification, at a
concentration of 3.05 mg/1. That sample was above the 0.08 mg/1
treatability concentration. Furthermore, antimony is often
recovered from lead-copper-zinc ores. Therefore, lead is
selected for further consideration for limitation.
Mercury was detected in seven samples at concentrations ranging
from 0.015 to 12.6 mg/1. Six of those samples were above the
0.036 mg/1 treatability concentration. Therefore, mercury is
selected for further consideration for limitation.
Zinc was found in two of eight samples at quantifiable concentra-
tions (0.10 and 0.27 mg/1). One of those samples was above the
0.23 mg/1 concentration considered achievable by identified
treatment technology. Furthermore, antimony is often recovered
from copper-lead-zinc ores. Therefore, zinc is selected for
further consideration for limitation in this subcategory.
36
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PRIMARY ANTIMONY SUBCATEGORY
SECTION VII
CONTROL AND TREATMENT TECHNOLOGIES
The preceding sections of this supplement discussed the sources,
flows, and characteristics of the wastewaters from primary anti-
mony plants. This section summarizes the description of these
wastewaters and indicates the treatment technologies which are
currently practiced in the primary antimony subcategory for each
waste stream. Secondly, this section presents the control and
treatment technology options which were examined by the Agency
for possible application to the primary antimony subcategory.
CURRENT CONTROL AND TREATMENT PRACTICES
Control and treatment technologies are discussed in general in
Section VII of the General Development Document. The basic prin-
ciples of these technologies and the applicability to wastewater
similar to that found in this subcategory are presented there.
This section presents a summary of the control and treatment
technologies that are currently being applied to each of the
sources generating wastewater in this subcategory. As discussed
in Section V, wastewater associated with the primary antimony
subcategory is characterized by the presence of the toxic metal
pollutants and suspended solids. Generally, these pollutants are
present at concentrations above treatability. This analysis is
supported by the raw (untreated) wastewater presented in Section
V. These wastewater streams may be combined to allow plants to
take advantage of economies of scale. The options selected for
consideration for BPT, BAT, BDT, and pretreatment based on com-
bined treatment of these compatible waste streams will be summa-
rized toward the end of this section.
SODIUM ANTIMONATE AUTOCLAVE WASTEWATER
Sodium antimonate (NaSb03> is manufactured by autoclaving the
antimony-bearing solution from the leaching process with oxygen.
The autoclave wastewater is expected to contain treatable
concentrations of suspended solids and toxic metals, and it may
also contain toxic organic pollutants. One plant which manu-
factures sodium antimonate achieves zero discharge of this stream
using evaporation ponds.
Another plant recovers sodium antimonate for recycle to leaching
from spent electrowinning solution by autoclaving. That process
for product recovery is considered to be a wastewater treatment
step and is distinguished from autoclaving to produce sodium
antimonate as a product.
39
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FOULED ANOLYTE
Antimony metal is produced by electrowinning the pregnant solu-
tion from the leaching process. All three of the plants which
practice electrowinning recycle barren electrolyte to leaching.
One plant reports total recycle of the spent electrowinning solu-
tion. The second plant spray dries the solution and recycles the
dried salts. The third plant recycles some of the electrolyte
but discharges the fouled anolyte portion. That fouled anolyte
contains toxic metals and suspended solids. Sodium antimonate is
recovered from the stream by autoclaving, and the autoclave
wastewater is discharged to a tailings pond where settling
occurs before discharge to a river.
CONTROL AND TREATMENT OPTIONS
The Agency examined two control and treatment technology options
that are applicable to the primary antimony subcategory. The
options selected for evaluation represent applicable end-of-pipe
treatment technologies.
OPTION A
The Option A treatment scheme for the primary antimony subcate-
gory consists of chemical precipitation and sedimentation of both
waste streams. Chemical precipitation and sedimentation consists
of lime addition to precipitate metals followed by gravity
sedimentation for the removal of suspended solids, including the
metal precipitates. Vacuum filtration is used to dewater the
sludge.
OPTION C
Option C for the primary antimony subcategory consists of all
control and treatment requirements of Option A (chemical precipi-
tation and sedimentation) plus multimedia filtration technology
added at the end of the Option A treatment scheme. Multimedia
filtration is used to remove suspended solids, including precipi-
tates of toxic metals, beyond the concentration attainable by
gravity sedimentation. The filter suggested is of the gravity,
mixed-media type, although other filters, such as rapid sand
filters, would perform satisfactorily.
Also, the Agency is considering the need to incorporate some
measure of toxic organic pollutant removal under both Options A
and C, such as activated carbon adsorption, if further investi-
gation shows a need for such measure.
40
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PRIMARY ANTIMONY SUBCATEGORY
SECTION VIII
COSTS, ENERGY, AND NONWATER QUALITY ASPECTS
This section presents a summary of compliance costs for the
primary antimony subcategory and a description of the treatment
options and subcategory-specific assumptions used to develop
these estimates. Together with the estimated pollutant removal
performance presented in Sections X and XII of this supplement,
these cost estimates provide a basis for evaluating each regula-
tory option. These cost estimates are also used in determining
the probable economic impact of regulation on the subcategory at
different pollutant discharge levels. In addition, this section
addresses nonwater quality environmental impacts of wastewater
treatment and control alternatives, including air pollution,
solid wastes, and energy requirements, which are specific to the
primary antimony subcategory.
TREATMENT OPTIONS FOR EXISTING SOURCES
As discussed in Section VII, two treatment options have been
developed and considered in proposing limitations and standards
for the primary antimony subcategory. These options are summa-
rized below and schematically presented in Figures X-1 and X-2.
OPTION A
The Option A treatment scheme consists of chemical precipitation
and sedimentation technology.
OPTION C
Option C for the primary antimony subcategory consists of all
control and treatment requirements of Option A (chemical precipi-
tation and sedimentation) plus multimedia filtration technology
added at the end of the Option A treatment scheme.
Also, the Agency is considering the need to incorporate some
measure of toxic organic pollutant removal under both Options A
and C, such as activated carbon adsorption, if further investi-
gation shows a need for such measure.
COST METHODOLOGY
A detailed discussion of the methodology used to develop the com-
pliance costs is presented in Section VIII of the General Devel-
opment Document. Plant-by-plant compliance costs have been esti-
mated for the nonferrous metals manufacturing category and are
-------
presented in the administrative record supporting this regula-
tion. The costs developed for the proposed regulation are pre-
sented in Table VIII-1 for the direct dischargers in this
subcategory.
Each of the general assumptions used to develop compliance costs
is presented in Section VIII of the General Development Document.
No subcategory-specific assumptions were used in developing com-
pliance costs for the primary antimony subcategory.
NONWATER QUALITY ASPECTS
A general discussion of the nonwater quality aspects of the con-
trol and treatment options considered for the nonferrous metals
category is contained in Section VIII of the General Development
Document. Nonwater quality impacts specific to the primary anti-
mony subcategory, including energy requirements, solid waste and
air pollution are discussed below.
ENERGY REQUIREMENTS
The methodology used for determining the energy requirements for
the various options is discussed in Section VIII of the General
Development Document. Energy requirements for Option A are esti-
mated at 11,900 kWh/yr, and for Option C the estimated require-
ment is 14,600 kWh/yr. Option C energy requirements increase
over those for Option A because filtration is being added as an
end-of-pipe treatment technology. The energy requirements of
both options represent less than one percent of the total energy
presently consumed at the discharging plant. It is, therefore,
concluded that the energy requirements of the treatment options
considered will have no significant impact on total plant energy
consumption.
SOLID WASTE
Sludge generated in the primary antimony subcategory is due to
the precipitiaton of metal hydroxides and carbonates using lime.
Sludges associated with the primary antimony subcategory will
necessarily contain quantities of toxic metal pollutants. These
sludges are not subject to regulation as hazardous wastes since
wastes generated by primary smelters and refiners are currently
exempt from regulation by Act of Congress (Resource Conservation
and Recovery Act (RCRA), Section 3001 (b)), as interpreted by
EPA. If a small excess of lime is added during treatment, the
Agency does not believe these sludges would be identified as haz-
ardous under RCRA in any case. (Compliance costs include this
amount of lime.) This judgement is based on the results of
Extraction Procedure (EP) toxicity tests performed on similar
sludges (toxic metal-bearing sludges) generated by other indus-
tries such as the iron and steel industry. A small amount of
42
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excess lime was added during treatment, and the sludges subse-
quently generated passed the toxicty test. See CFR §261.24.
Thus, the Agency believes that the wastewater sludges will simi-
larly not be EP toxic if the recommended technology is applied.
Although it is the Agency's view that solid wastes generated as a
result of these guidelines are not expected to be hazardous, gen-
erators of these wastes must test the waste to determine if the
wastes meet any of the characteristics of hazardous waste (see 40
CFR 262.11).
If these wastes should be identified or are listed as hazardous,
they will come within the scope of RCRA's "cradle to grave" haz-
ardous waste management program, requiring regulation from the
point of generation to point of final disposition. EPA's genera-
tor standards would require generators of hazardous nonferrous
metals manufacturing wastes to meet containerization, labeling,
recordkeeping, and reporting requirements; if plants dispose of
hazardous wastes off-site, they would have to prepare a manifest
which would track the movement of the wastes from the generator's
premises to a permitted off-site treatment, storage, or disposal
facility. See 40 CFR 262.20 45 FR 33142 (May 19, 1980), as
amended at 45 FR 86973 (December 31, 1980). The transporter
regulations require transporters of hazardous wastes to comply
with the manifest system to assure that the wastes are delivered
to a permitted facility. See 40 CFR 263.20 45 FR 33151 (May 19,
1980), as amended at 45 FR 86973 (December 31, 1980). Finally,
RCRA regulations establish standards for hazardous waste treat-
ment, storage, and disposal facilities allowed to receive such
wastes. See 40 CRF Part 464 46 FR 2802 (January 12, 1981), 47 FR
32274 (July 26, 1982).
Even if these wastes are not identified as hazardous, they still
must be disposed of in compliance with the Subtitle D open dump-
ing standards, implementing 4004 of RCRA. See 44 FR 53438
(September 13, 1979).
It is estimated that the primary antimony subcategory will
generate 33 .metric tons of sludge per year when implementing the
proposed BPT treatment technology. The Agency has calculated as
part of the costs for wastewater treatment the cost of hauling
and disposing of these wastes. For more details, see Section
VIII of the General Development Document.
AIR POLLUTION
There is no reason to believe that any substantial air pollution
problems will result from implementation of chemical precipita-
tion, sedimentation, and multimedia filtration. These technolo-
gies transfer pollutants to solid waste and are not likely to
transfer pollutants to air.
43
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Table VIII-1
COST OF COMPLIANCE FOR THE PRIMARY ANTIMONY SUBCATEGORY
DIRECT DISCHARGERS
(March, 1982 Dollars)
Total Required Total
Option Capj-tal Cost Annual Cost
A $34,200 $17,300
C $41,250 $21,183
44
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PRIMARY ANTIMONY SUBCATEGORY
SECTION IX
BEST PRACTICABLE CONTROL TECHNOLOGY
CURRENTLY AVAILABLE
This section defines the effluent 'characteristics attainable
through the application of best practicable control technology
currently available (BPT), Section 301(b)(a)(A). BPT reflects
the existing performance by plants of various sizes, ages, and
manufacturing processes within the primary antimony subcategory,
as well as the established performance of the recommended BPT
systems. Particular consideration is given to the treatment
already in place at plants within the data base.
The factors considered in identifying BPT include the total cost
of applying the technology in relation to the effluent reduction
benefits from such application, the age of equipment and facili-
ties involved, the manufacturing processes used, nonwater quality
environmental impacts (including energy requirements), and other
factors the Administrator considers appropriate. In general, the
BPT level represents ,the average of the existing performances of
plants of various ages, sizes, processes, or other common charac-
teristics. Where existing performance is uniformly inadequate,
BPT may be transferred from a different subcategory or category.
Limitations based on transfer of technology are supported by a
rationale concluding that the technology is, indeed, transfera-
ble, and a reasonable prediction that it will be capable of
achieving the prescribed effluent limits (see Tanner's Council
of America v. Train. 540 F.2d 1188 (4th Cir. 1176).BPT focuses
on end-of-pipe treatment rather than process changes or internal
controls, except where such practices are common industry
practice.
TECHNICAL APPROACH TO BPT
The Agency studied the nonferrous metals category to identify the
processes used, the wastewater's generated, and the treatment pro-
cesses installed. Information was collected from industry using
data collection portfolios, and specific plants were sampled and
the wastewaters analyzed. In making technical assessments of
data, reviewing manufacturing processes, and assessing wastewater
treatment technology options, both indirect and direct dis-
chargers have been considered as a single group. An examination
of plants and processes did not indicate any process differences
based on the type of discharge, whether it be direct or indirect.
45
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As explained in Section IV, the primary antimony subcategory has
been subdivided into two potential wastewater sources. Since the
water use, discharge rates, and pollutant characteristics of each
of these wastewaters is potentially unique, effluent limitations
will be developed for each of the two subdivisions.
For each of the subdivisions, a specific approach was followed
for the development of BPT mass limitations. The first require-
ment to calculate these limitations is to account for production
and flow variability from plant to plant. Therefore, a unit of
production or production normalizing parameter (PNP) was deter-
mined for each waste stream which could then be related to the
flow from the process to determine a production normalized flow.
Selection of the PNP for each process element is discussed in
Section IV. Each plant within the subcategory was then analyzed
to determine (1) which subdivisions were present, (2) the spe-
cific flow rates generated for each subdivision, and (3) the
specific production normalized flows for each subdivision. This
analysis is discussed in detail in Section V. Nonprocess waste-
waters such as rainfall runoff and noncontact cooling water are
not considered in the analysis.
Production normalized flows for each subdivision were then ana-
lyzed to determine the flow to be used as part of the basis for
BPT mass limitations. The selected flow (sometimes referred to
as the BPT regulatory flow or BPT discharge rate) reflects the
water use controls which are common practices within the cate-
gory. The BPT regulatory flow is based on the average of all
applicable data. Plants with normalized flows above the average
may have to implement some method of flow reduction to achieve
the BPT limitations.
The second requirement to calculate mass limitations is the set
of concentrations that are achievable by application of the BPT
level of treatment technology. Section VII discusses the various
control and treatment technologies which are currently in place
for each wastewater source. In most cases throughout the nonfer-
rous metals manufacturing industry, the current control and
treatment technologies consist of chemical precipitation and
sedimentation (lime and settle) technology.
Using these regulatory flows and the achievable concentrations,
the next step is to calculate mass loadings for each wastewater
source or subdivision. This calculation was made on a stream-
by-stream basis, primarily because plants in this subcategory may
perform one or more of the operations in various combinations.
The mass loadings (milligrams of pollutant per metric ton of
production - mg/kkg) were calculated by multiplying the BPT
regulatory flow (1/kkg) by the concentration achievable by the
BPT level of treatment technology (mg/1) for each pollutant
parameter to be limited under BPT. These mass loadings are
46
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published in the Federal Register and in CFR Part 400 as the
effluent limitations guidelines.
The mass loadings which are allowed under BPT for each plant will
be the sum of the individual mass loadings for the various waste-
water sources which are found at particular plants. Accordingly,
all the wastewater generated within a plant may be combined for
treatment in a single or common treatment system, but the
effluent limitations for these combined wastewaters are based on
the various wastewater sources which actually contribute to the
combined flow. This method accounts for the variety of combina-
tions of wastewater sources and production processes which may be
found at primary antimony plants.
The Agency usually establishes wastewater limitations in terms of
mass rather than concentration. This approach prevents the use
of dilution as a treatment method (except for controlling pH).
The production normalized wastewater flow (1/kkg) is a link
between the production operations and the effluent limitations.
The pollutant discharge attributable to each operation can be
calculated from the normalized flow and effluent concentration
achievable by the treatment technology and summed to derive an
appropriate limitation for each plant.
INDUSTRY COST AND POLLUTANT REMOVAL ESTIMATES
In balancing costs in relation to pollutant removal estimates,
EPA considers the volume and nature of existing discharges, the
volume and nature of discharges expected after application of
BPT, the general environmental effects of the pollutants, and the
cost and economic impacts of the required pollution control
level. The Act does not require or permit consideration of water
quality problems attributable to particular point sources or
industries, or water quality improvements in particular water
quality bodies. Accordingly, water quality considerations were
not the basis for selecting the proposed BPT. See Weyerhaeuser
Company v. Costle. 590 F.2d 1011 (D.C. Cir. 1978).
The methodology for calculating pollutant removal estimates and
plant compliance costs is discussed in Section X. Table X-1
shows the pollutant removal estimates for each treatment option
for direct dischargers. Compliance costs for direct dischargers
are presented in Table X-2.
BPT OPTION SELECTION
The technology basis for the BPT limitations is Option A, chemi-
cal precipitation and sedimentation technology to remove metals
and solids from combined wastewaters and to control pH. These
technologies are not in-place at the one discharger in this
47
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subcategory. The BPT treatment scheme is presented in Figure
IX-1. The Agency is also considering the possibility of requir-
ing activated carbon adsorption as an effluent polishing step to
control the discharge of toxic organic pollutants. Toxic organic
pollutants may be present due to the coke used as a raw material
in the smelting furnace.
Implementation of the proposed BPT limitations will remove
annually an estimated 2,642 kg of toxic metals and 965 kg of TSS
over estimated current discharge, which is equal to the raw waste
generated because no treatment is in-place. The Agency projects
a capital cost of approximately $34,200 and an annualized cost of
approximately $17,300 for achieving proposed BPT.
WASTEWATER DISCHARGE RATES
A BPT discharge rate is calculated for each subdivision based on
the average of the flows of the existing plants, as determined
from analysis of data collection portfolios. The discharge rate
is used with the achievable treatment concentrations to determine
BPT effluent limitations. Since the discharge rate may be dif-
ferent for each wastewater source, separate production normalized
discharge rates for each of the two wastewater sources are dis-
cussed below and summarized in Table IX-1. The discharge rates
are normalized on a production basis by relating the amount of
wastewater generated to the mass of product which is produced by
the process associated with the waste stream in question. These
production normalizing parameters, or PNPs, are also listed in
Table IX-1.
Section V of this document further describes the discharge flow
rates and presents the water use and discharge flow rates for
each plant by subdivision in Tables V-1 and V-2.
SODIUM ANTIMONATE AUTOCLAVE WASTEWATER
The BPT wastewater discharge allowance for sodium antimonate
autoclave wastewater is 7,093 1/kkg (1,704 gal/ton) of antimony
contained in sodium antimonate product. This rate is allocated
to any plant which produces sodium antimonate from a pregnant
leaching solution by an autoclaving operation. No allowance is
given when sodium antimonate is recovered for recycling by
autoclaving fouled anolyte because in that case, autoclaving is
considered to be a wastewater treatment step for product
recovery.
No recycle or reuse of this wastewater is reported at the one
plant that generates this stream. Because that plant did not
provide flow rate information in the dcp, the BPT discharge
allowance for sodium antimonate autoclave wastewater was assumed
48
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to be equal to the BPT discharge allowance for fouled anolyte
using the antimony content of the product as the production nor-
malizing parameter.
FOULED ANOLYTE
The BPT wastewater discharge allowance for fouled anolyte is
7,093 1/kkg (1,704 gal/ton) of antimony metal produced by elec-
trowinning. This rate is allocated to any plant which recovers
antimony by electrowinning it from a pregnant leaching solution.
The BPT allowance is based on the discharge rate at the only
plant that reported this stream. That plant recycles some of the
spent electrowinnning solution, but did not provide flow rate
information for the recycled stream. That plant also recovers
and recycles sodium antimonate from the fouled anolyte before
disposal.
REGULATED POLLUTANT PARAMETERS
The raw wastewater concentrations from individual operations and
the subcategory as a whole were examined to select certain pollu-
tant parameters for limitation. This examination and evaluation
is presented in Sections VI and X. A total of six pollutants or
pollutant parameters are selected for limitation under BPT and
are listed below:
114. antimony
115. arsenic
122. lead
123. mercury
TSS
pH
EFFLUENT LIMITATIONS
The treatable concentrations achievable by application of the
proposed BPT are discussed in Section VII of the General Develop-
ment Document and summarized there in Table VII-19. These treat-
able concentrations (both one-day maximum and monthly average
values) are multiplied by the BPT normalized discharge flows
summarized in Table IX-1 to calculate the mass of pollutants
allowed to be discharged per mass of product. The results of
these calculations in milligrams of pollutant per kilogram of
product represent the BPT effluent limitations and are presented
in Table IX-2 for each individual waste stream.
49
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Table IX-1
BPT WASTEWATER DISCHARGE RATES FOR THE
PRIMARY ANTIMONY SUBCATEGORY
Wastewater Stream
Sodium antimonate auto-
clave wastewater
Fouled anolyte
BPT Normalized
Discharge Rate
1/kkg gal/ton
7,093
7,093
1 ,704
1 ,704
Production
Normalized
Parameter
Antimony contained
in sodium antimon-
ate product
Antimony metal
produced by elec-
trowinning
50
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Table IX-2
BPT MASS LIMITATIONS FOR THE
PRIMARY ANTIMONY SUBCATEGORY
(a) Sodium Antimonate Autoclave Wastewater
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of antimony contained in
sodium antimonate product
Antimony 20.360 9.079
Arsenic 14.820 6.596
Lead 2.979 1.419
Mercury 1.773 0.709
Total suspended 290.800 138.300
solids
pH Within the range of 7.5 to 10.0
at all times
(b) Fouled Anolyte
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
tug/kg (Ib/million Ibs) of antimony metal produced
by electrowinning
Antimony 20.360 9.079
Arsenic 14.820 6.596
Lead 2.979 1.419
Mercury 1.773 0.709
Total suspended 290.800 138.300
solids
pH Within the range of 7.5 to 10.0
at all times
51
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PRIMARY ANTIMONY SUBCATEGORY
SECTION X
BEST AVAILABLE TECHNOLOGY ECONOMICALLY ACHIEVABLE
The effluent limitations which must be achieved by July 1, 1984
are based on the best control and treatment technology used by a
specific point source within the industrial category or subcate-
gory, or by another industry where it is readily transferable.
Emphasis is placed on additional treatment techniques applied at
the end of the treatment systems currently used, as well as
reduction of the amount of water used and discharged, process
control, and treatment technology optimization.
The factors considered in assessing best available technology
economically achievable (BAT) include the age of equipment and
facilities involved, the process used, process changes, nonwater
quality environmental impacts (including energy requirements),
and the costs of application of such technology (Section 304(b)
(2)(B) of the Clean Water Act). At a minimum, BAT represents the
best available technology economically achievable at plants of
various ages, sizes, processes, or other characteristics. Where
the Agency has found the existing performance to be uniformly
inadequate, BAT may be transferred from a different subcategory
or category. BAT may include feasible process changes or
internal controls, even when not in common industry practice.
The required assessment of BAT considers costs, but does not
require a balancing of costs against pollutant removals (see
Weyerhaeuser v. Costle. 11 ERG 2149 (D.C. Cir. 1978)). However,
in assessing the proposed BAT, the Agency has given substantial
weight to the economic achievability of the technology.
TECHNICAL APPROACH TO BAT
The Agency reviewed a wide range of technology options and evalu-
ated the available possibilities to ensure that the most effec-
tive and beneficial technologies were used as the basis of BAT.
To accomplish this, the Agency elected to examine two technology
options which could be applied to the primary antimony subcate-
gory as alternatives for the basis of BAT effluent limitations.
For the development of BAT effluent limitations, mass loadings
were calculated for each wastewater source or subdivision in the
subcategory using the same technical approach as described in
Section IX for BPT limitations development. The differences in
the mass loadings for BPT and BAT are due to increased treatment
53
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effectiveness achievable with the more sophisticated BAT treat-
ment technology.
The treatment technologies considered for BAT are summarized
below:
Option A (Figure X-1):
Chemical precipitation and sedimentation
Option C (Figure X-2):
Chemical precipitation and sedimentation
Multimedia filtration
The two options examined for BAT are discussed in greater detail
below. The first option considered (Option A) is the same as
the BPT treatment and control technology which was presented in
the previous section. The second option represents substantial
progress toward the reduction of pollutant discharges above and
beyond the progress achievable by BPT.
OPTION A
Option A for the primary antimony subcategory is equivalent to
the control and treatment technologies^ which were analyzed for
BPT in Section IX (see Figure X-1). The BPT end-of-pipe treat-
ment scheme includes chemical precipitation .and sedimentation
(see Figure IX-1). The discharge rates for Option A are equal to
the discharge rates allocated to each stream as a BPT discharge
flow. As discussed earlier, EPA is also considering the possi-
bility of activated carbon adsorption for controlling toxic
organic pollutants.
OPTION C
Option C for the primary antimony subcategory consists of all
control and treatment requirements of Option A (chemical precipi-
tation and sedimentation) plus multimedia filtration technology
added at the end of the Option A treatment scheme (see Figure
X-2). Multimedia filtration is used to remove suspended solids,
including precipitates of toxic metals, beyond the concentrations
attainable by gravity sedimentation. The filter suggested is of
the gravity, mixed media type, although other forms of filters,
such as rapid sand filters or pressure filters, would perform
satisfactorily. As discussed earlier, EPA is also considering
the possibility of activated carbon adsorption for controlling
toxic organic pollutants.
54
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INDUSTRY COST AND POLLUTANT REMOVAL ESTIMATES
As one means of evaluating each technology option, EPA developed
estimates of the pollutant removals and the compliance costs
associated with each option. The methodologies are described
below.
POLLUTANT REMOVAL ESTIMATES
A complete description of the methodology used to calculate the
estimated pollutant removal achieved by the application of the
various treatment options is presented in Section X of the
General Development Document. In short, sampling data collected
during the field sampling program were used to characterize the
major waste streams considered for regulation. At each sampled
facility, the sampling data was production normalized for each
unit operation (i.e., mass of pollutant generated per mass of
product manufactured). This value, referred to as the raw waste,
was used to estimate the mass of toxic pollutants generated
within the primary antimony subcategory. The pollutant removal
estimates were calculated for each plant by first estimating the
total mass of each pollutant in the untreated wastewater. This
was calculated by first multiplying the raw waste values by the
corresponding production value for that stream and them summing
these values for each pollutant for every stream generated by the
plant.
Next, the volume of wastewater discharged after the application
of each treatment option was estimated for each operation at each
plant by comparing the actual discharge to the regulatory flow.
The smaller of the two values was selected and summed with the
other plant flows. The mass of pollutant discharged was then
estimated by multiplying the achievable concentration values
attainable with the option (mg/1) by the estimated volume of
process wastewater discharged by the subcategory. The mass of
pollutant removed is the difference between the estimated mass of
pollutant generated within the subcategory and the mass of pollu-
tant discharged after application of the treatment option. The
pollutant removal estimates for direct dischargers in the primary
antimony subcategory are presented in Table X-1.
COMPLIANCE COSTS
In estimating subcategory-wide compliance costs, the first step
was to develop a cost estimation model, relating the total costs
associated with installation and operation of wastewater treat-
ment technologies to plant process wastewater discharge. EPA
applied the model to each plant. The plant's investment and
operating costs are determined by what treatment it has in place
and by its individual process wastewater discharge flow. As
55
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discussed above, this flow is either the actual or the BAT regu-
latory flow, whichever is lesser. The final step was to annual-
ize the capital costs, and to sum the annual!zed capital costs,
and the operating and maintenance costs for each plant, yielding
the cost of compliance for the subcategory. The compliance costs
associated with the various options are presented in Table X-2
for direct discharges in the primary antimony subcategory. These
costs were used in assessing economic achievability.
BAT OPTION SELECTION
EPA has selected Option C which includes chemical precipitation,
sedimentation, and multimedia filtration. The estimated capital
cost of proposed BAT is 41,250 dollars (1982 dollars) and the
annual cost is 21,183 dollars (1982 dollars). The end-of-pipe
treatment configuration for Option C is presented in Figure X-2.
As discussed earlier, EPA is also considering the possibility of
activated carbon adsorption for controlling toxic organic
pollutants.
EPA is proposing multimedia filtration as part of the BAT techno-
logy because this technology results in additional removal of
toxic metals. Filtration is also presently demonstrated at 25
plants throughout the nonferrous metals manufacturing category.
Filtration adds reliability to the treatment system by making it
less susceptible to operator error and to sudden changes in raw
wastewater flow and concentrations.
Implementation of the control and treatment technologies of
Option C would remove annually an estimated 2,644 kilograms of
toxic metal pollutants, which is 1.3 kilograms of toxic metal
pollutants over the estimated BPT removal.
WASTEWATER DISCHARGE RATES
A BAT discharge rate was calculated for each subdivision based
upon the flows of the existing plants, as determined from analy-
sis of the data collection portfolios. The discharge rate is
used with the achievable treatment concentrations to determine
BAT effluent limitations. Since the discharge rate may be dif-
ferent for each wastewater source, separate production normalized
discharge rates for each of the two wastewater sources were
determined and are summarized in Table X-3. The discharge rates
are normalized on a production basis by relating the amount of
wastewater generated to the mass of product which is produced by
the process associated with the waste stream in question. These
production normalizing parameters, or PNPs, are also listed in
Table X-3.
56
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The BAT discharge rates reflect no flow reduction requirements as
compared to the BPT option flows. In-process flow reduction was
not considered achievable for any waste streams in this subcate-
gory. Consequently, the BAT and BPT production normalized
discharge flows are identical.
REGULATED POLLUTANT PARAMETERS
In implementing the terms of the Consent Agreement in NRDC v.
Train, Op. Cit., and 33 U. S.C. 1314(b)(2)(A and B) (197577 the
Agency placed particular emphasis on the toxic pollutants. The
raw wastewater concentrations from individual operations and the
subcategory as a whole were examined to select certain pollutants
and pollutant parameters for limitation. This examination and
evaluation was presented in Section VI. The Agency, however, has
chosen not to regulate all seven toxic pollutants selected for
further consideration in this analysis.
The high cost associated with analysis for toxic metal pollutants
has prompted EPA to develop an alternative method for regulating
and monitoring toxic pollutant discharges from the nonferrous
metals manufacturing category. Rather than developing specific
effluent mass limitations and standards for each of the toxic
metals found in treatable concentrations in the raw wastewater
from a given subcategory, the Agency is proposing effluent mass
limitations only for those pollutants generated in the greatest
quantities as shown by the pollutant removal analysis. The
pollutants selected for specific limitation are listed below:
11 4. antimony
11 5. arsenic
122. lead
123. mercury
By establishing limitations and standards for certain toxic metal
pollutants, dischargers will attain the same degree of control
over toxic metal pollutants as they would have been required to
achieve had all the toxic metal pollutants been directly limited.
This approach is technically justified since the treatable con-
centrations used for chemical precipitation and sedimentation
technology are based on optimized treatment for concomitant
multiple metals removal. Thus, even though metals have somewhat
different theoretical solubilities, they will be removed at very
nearly the same rate in a chemical precipitation and sedimenta-
tion treatment system operated for multiple metals removal.
Filtration as part of the technology basis is likewise justified
because this technology removes metals non-preferentially.
57
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The toxic metal pollutants selected for specific limitation in
the primary antimony subcategory to control the discharges of
toxic metal pollutants are antimony, arsenic, lead, and mercury.
The following toxic metal pollutants are excluded from limitation
on the basis that they are effectively controlled by the limita-
tions developed for antimony, arsenic, lead, and mercury;
118. cadmium
120. copper
128. zinc
EFFLUENT LIMITATIONS
The concentrations, achievable by application of BAT are discussed
in Section VII of the General Development Document and summarized
there in Table VII-19. The treatable concentrations both one day
maximum and monthly average values are multiplied by the BAT nor-
malized discharge flows summarized in Table X-3 to calculate the
mass of pollutants allowed to be discharged per mass of product.
The results of these calculations in milligrams of pollutant per
kilogram of product represent the BAT effluent limitations and
are presented in Table X-4 for each waste stream.
58
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59
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Table X-2
COST OF COMPLIANCE FOR THE PRIMARY ANTIMONY SUBCATEGORY
DIRECT DISCHARGERS
Total Required Total
Capital Cost Annual Cost
Option (1982 Dollars) (1982 Dollars)
A $34,200 $17,300
C $41,250 $21,183
60
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Table X-3
BAT WASTEWATER DISCHARGE RATES FOR THE
PRIMARY ANTIMONY SUBCATEGORY
Wastewater Stream
Sodium antimonate auto-
clave wastewater
Fouled anolyte
BAT Normalized
Discharge Rate
1/kkg gal/ton
7,093
7,093
1 ,704
1 ,704
Production
Normalized
Parameter
Antimony contained
in sodium antimon-
ate product
Antimony metal
produced by elec-
trowinning
61
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Table X-4
BAT MASS LIMITATIONS FOR THE
PRIMARY ANTIMONY SUBCATEGORY
(a) Sodium Antimonate Autoclave Wastewater
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of antimony contained in
sodium antimonate product
Antimony 13.690 6.100
Arsenic 9.859 4.398
Lead 1.986 0.922
Mercury 1.064 0.426
(b) Fouled Anolyte
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of antimony metal produced
by electrowinning
Antimony 13.690 6.100
Arsenic 9.859 4.398
Lead 1.986 0.922
Mercury 1.064 0.426
62
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64
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PRIMARY ANTIMONY SUBCATEGORY
SECTION XI
NEW SOURCE PERFORMANCE STANDARDS
The basis for new source performance standards (NSPS) under Sec-
tion 306 of the Act is the best available demonstrated technology
(BDT). New plants have the opportunity to design the best and
most efficient production processes and wastewater treatment
technologies without facing the added costs and restrictions
encountered in retrofitting an existing plant. Therefore, Con-
gress directed EPA to consider the best demonstrated process
changes, in-plant controls, and end-of-pipe treatment technolo-
gies which reduce pollution to the maximum extent feasible.
This section describes the technologies for treatment of waste-
water from new sources and presents mass discharge standards for
regulatory pollutants for NSPS in the primary antimony subcate-
gory, based on the selected treatment technology.
TECHNICAL APPROACH TO NSPS
New source performance standards are equivalent to the best
available technology (BAT) selected for currently existing pri-
mary antimony plants. This result is a consequence of careful
review by the Agency of a wide range of technology options for
new source treatment systems which is discussed in Section IX of
the General Development Document. This review of the primary
antimony subcategory found no new, economically feasible, demon-
strated technologies which could be considered an improvement
over those chosen for consideration for BAT. Additionally, there
was nothing found to indicate that the wastewater flows and char-
acteristics of new plants would not be similar to those from
existing plants, since the processes used by new sources are not
expected to differ from those used at existing sources. Conse-
quently, BAT production normalized discharge rates, which are
based on the best existing practices of the subcategory, can also
be applied to new sources. These rates are presented in Table
XI-1.
Treatment technologies considered for the NSPS options are iden-
tical to the treatment technologies considered for the BAT
options. These options are:
OPTION A
Chemical precipitation and sedimentation
65
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OPTION C
Chemical precipitation and sedimentation
Multimedia filtration
NSPS OPTION SELECTION
EPA is proposing that the best available demonstrated technology
for the primary antimony subcategory be equivalent to Option C
(chemical precipitation, sedimentation, and multimedia filtra-
tion) . This technology is demonstrated by 25 plants in the
nonferrous metals manufacturing category. As discussed earlier,
EPA is also considering the possibility of activated carbon
adsorption as an effluent polishing step to control the discharge
of toxic organic pollutants.
The wastewater flow rates for NSPS are the same as the BAT flow
rates. A review of the industry indicates that no new demon-
strated technologies that improve on BAT technology exist. EPA
does not believe that new plants could achieve any flow reduction
beyond the allowances proposed for BAT, therefore, the NSPS
allowances are equal to those for BAT.
REGULATED POLLUTANT PARAMETERS
The Agency has no reason to believe that the pollutants that will
be found in treatable concentrations in proceses within new
sources will be any different than with existing sources.
Accordingly, pollutants and pollutant parameters selected for
limitation under NSPS, in accordance with the rationale of Sec-
tions VI and X, are identical to those selected for BAT. The
conventional pollutant parameters TSS and pH are also selected
for limitation.
NEW SOURCE PERFORMANCE STANDARDS
The NSPS discharge flows for each wastewater source are the same
as the discharge rates for BAT and are shown in Table XI-1. The
mass of pollutant allowed to be discharged per mass of product is
based on the product of the appropriate treatable concentration
(mg/1) and the production normalized wastewater discharge flows
(1/kkg). The treatable concentrations are listed in Table VII-19
of the General Development Document. The results of these cal-
culations are the production-based new source performance stan-
dards. These standards are presented in Table XI-2, in
milligrams of pollutant per kilogram of product.
66
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Table XI-1
NSPS WASTEWATER DISCHARGE RATES FOR THE
PRIMARY ANTIMONY SUBCATEGORY
Wastewater Stream
Sodium antimonate auto-
clave wastewater
Fouled anolyte
NSPS Normalized
Discharge Rate
1/kkg gal/ton
7,093
7,093
1 ,704
1 ,704
Production
Normalized
Parameter
Antimony contained
in sodium antimon-
ate product
Antimony metal
produced by elec-
trowinning
67
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Table XI-2
NSPS FOR THE PRIMARY ANTIMONY SUBCATEGORY
(a) Sodium Antimonate Autoclave Wastewater
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
rag/kg (Ib/million Ibs) of antimony contained in
sodium antimonate product
Antimony 13.690 6.100
Arsenic 9.859 4.398
Lead 1.986 0.922
Mercury 1.064 0.426
Total suspended 106.400 85.120
solids
pH Within the range of 7.5 to 10.0
at all times
(b) Fouled Anolyte
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of antimony metal produced
by electrowinning
Antimony 13.690 6.100
Arsenic 9.859 4.398
Lead 1.986 0.922
Mercury 1.064 0.426
Total suspended 106.400 85.120
solids
pH Within the range of 7.5 to 10.0
at all times
68
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PRIMARY ANTIMONY SUBCATEGORY
SECTION XII
PRETREATMENT STANDARDS
Section 307(b) of the Act requires EPA to promulgate pretreatment
standards for existing sources (PSES), which must be achieved
within three years of promulgation. PSES are designed to prevent
the discharge of pollutants which pass through, interfere with,
or are otherwise incompatible with the operation of publicly
owned treatment works (POTW). The Clean Water Act of 1977
requires pretreatment for pollutants, such as heavy metals, that
limit POTW sludge management alternatives. Section 307(c) of the
Act requires EPA to promulgate pretreatment standards for new
sources (PSNS) at the same time that it promulgates NSPS. New
indirect discharge facilities, like new direct discharge facili-
ties, have the opportunity to incorporate the best available
demonstrated technologies, inlcuding process changes, in-plant
controls, and end-of-pipe treatment technologies, and to use
plant site selection to ensure adequate treatment system instal-
lation. Pretreatment standards are to be technology based,
analogous to the best available technology for removal of toxic
pollutants.
Pretreatment standards for existing sources (PSES) will not be
proposed for the primary antimony subcategory because there are
no existing indirect dischargers in this subcategory. However,
pretreatment standards for new sources (PSNS) will be proposed.
This section describes the control and treatment technologies for
pretreatment of process wastewaters from new sources in the pri-
mary antimony subcategory. Pretreatment standards for regulated
pollutants are presented based on the selected control and treat-
ment technology.
TECHNICAL APPROACH TO PRETREATMENT
Before proposing pretreatment standards, the Agency examines
whether the pollutants discharged by the industry pass through
the POTW or interfere with the POTW operation or its chosen
sludge disposal practices. In determining whether pollutants
pass through a well-operated POTW achieving secondary treatment,
the Agency compares the percentage of a pollutant removed by POTW
with the percentage removed by direct dischargers applying the
best available technology economically achievable. A pollutant
is deemed to pass through the POTW when the average percentage
removed nationwide by well-operated POTW meeting secondary
69
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treatment requirements, is less than the percentage removed by
direct dischargers complying with BAT effluent limitations guide-
lines for that pollutant. (See generally, 46 FR at 9415-16
(January 28, 1981)).
This definition of pass through satisfies two competing objec-
tives set by Congress: (1) that standards for indirect dis-
chargers be equivalent to standards for direct dischargers while
at the same time, (2) that the treatment capability and perfor-
mance of the POTW be recognized and taken into account in regu-
lating the discharge of pollutants from indirect dischargers.
The Agency compares percentage removal rather than the mass or
concentration of pollutants discharged because the latter would
not take into account the mass of pollutants discharged to the
POTW from non-industrial sources or the dilution of the pollu-
tants in the POTW effluent to lower concentrations due to the
addition of large amounts of non-industrial wastewater.
PRETREATMENT STANDARDS FOR NEW SOURCES
Options for pretreatment of wastewaters from new sources are
based on increasing the effectiveness of end-of-pipe treatment
technologies. All in-plant changes and applicable end-of-pipe
treatment processes have been discussed previously in Sections X
and XI. The options for PSNS, therefore, are the same as the BAT
options discussed in Section X.
A description of each option is presented in Section X, while a
more detailed discussion, including pollutants controlled by each
treatment process is presented in Section VII of the General
Development Document.
Treatment technologies considered for the PSNS options are:
OPTION A
Chemical precipitation and sedimentation
OPTION C
Chemical precipitation and sedimentation
Multimedia filtration
PSNS OPTION SELECTION
Option C (chemical precipitation, sedimentation, and multimedia
filtration) has been selected as the regulatory approach for
pretreatment standards for new sources on the basis that it
70
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achieves effective removal of toxic pollutants and is demon-
strated by 25 plants throughout the nonferrous metals manufac-
turing category. As discussed earlier, EPA is considering the
possible addition of activated carbon adsorption for the control
of toxic organic pollutants.
The wastewater discharge rates for PSNS are identical to the BAT
discharge rates for each waste stream. The PSNS discharge rates
are shown in Table XII-1. No additional flow reduction measures
for PSNS are feasible; EPA does not believe that new plants could
achieve flow reduction beyond the allowances proposed for BAT.
REGULATED POLLUTANT PARAMETERS
Pollutants selected for limitation, in accordance with the ratio-
nale of Sections VI and X, are identical to those selected for
limitation for BAT. It is necessary to propose PSNS to prevent
the pass-through of antimony, arsenic, lead, and mercury, which
are the limited pollutants.
PRETREATMENT STANDARDS FOR NEW SOURCES
Pretreatment standards for new sources are based on the treatable
concentrations from the selected treatment technology, (Option
C), and the discharge rates determined in Section X for BAT. A
mass of pollutant per mass of product (mg/kg) allocation is given
for each subdivision within the subcategory. This pollutant
allocation is based on the product of the treatable concentration
from the proposed treatment (mg/1) and the production normalized
wastewater discharge rate (1/kkg). The achievable treatment
concentrations for BAT are identical to those for PSNS. These
concentrations are listed in Table VII-19 of the General
Development Document. PSNS is presented in Table XII-2.
71
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Table XII-1
PSNS WASTEWATER DISCHARGE RATES FOR THE
PRIMARY ANTIMONY SUBCATEGORY
Wastewater Stream
Sodium antimonate auto-
clave wastewater
Fouled anolyte
PSNS Normalized
Discharge Rate
1/kkggal/ton
7,093
7,093
1 ,704
1 ,704
Production
Normalized
Parameter
Antimony contained
in sodium antimon-
ate product
Antimony metal
produced by elec-
trowinning
72
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Table XII-2
PSNS FOR THE PRIMARY ANTIMONY SUBCATEGORY
(a) Sodium Antimonate Autoclave Wastewater
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of antimony contained in
sodium antimonate product
Antimony 13.690 6.100
Arsenic 9.859 4.398
Lead 1.986 0.922
Mercury 1.064 0.426
(b) Fouled Anolyte
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of antimony metal produced
by electrowinning
Antimony 13.690 6.100
Arsenic 9.859 4.398
Lead 1.986 0.922
Mercury 1.064 0.426
73
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74
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PRIMARY ANTIMONY SUBCATEGORY
SECTION XIII
BEST CONVENTIONAL POLLUTANT CONTROL TECHNOLOGY
EPA is not proposing best conventional pollutant control technol-
ogy (BCT) for the primary antimony subcategory at this time.
75
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