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PRIMARY MOLYBDENUM AND RHENIUM SUBCATEGORY
SECTION VII
CONTROL AND TREATMENT TECHNOLOGIES
The preceding sections of this supplement discussed the sources,
flows, and characteristics of the wastewaters generated in the
primary molybdenum and rhenium subcategory. This section sum-
marizes the description of these wastewaters and indicates the
level of treatment which is currently practiced for each waste
stream. Secondly, this section presents the control and treat-
ment technology options which were examined by the Agency for
possible application to the primary molybdenum and rhenium
subcategory.
In addition, the Agency is proposing to expand the applicability
of the promulgated metallurgical acid plants subcategory effluent
limitations and standards to include the molybdenum sulfuric acid
plants. This section will also present the technology basis for
these promulgated limitations and standards for all the appropri-
ate regulatory levels.
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 applied to each of the sources
generating wastewater in this subcategory. As discussed in
Section V, wastewater associated with the primary molybdenum and
rhenium subcategory is characterized by the presence of the toxic
metal pollutants, ammonia, and suspended solids. This analysis
is supported by the raw (untreated) wastewater data in Section V.
Generally, these pollutants are present in each of the waste
streams at concentrations above treatability, and these waste
streams are commonly combined for treatment. Construction of one
wastewater treatment system for combined treatment allows plants
to take advantage of economies of scale, and in some instances,
to combine streams of differing alkalinity to reduce treatment
chemical requirements. Three plants in this subcategory cur-
rently have combined wastewater treatment systems, consisting of
chemical precipitation and sedimentation. One of these three
plants also practices ammonia stripping. Three options have been
selected for consideration for BPT, BAT, NSPS, and pretreatment
standards in this subcategory, based on combined treatment of
these compatible waste streams.
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MOLYBDENUM SULFIDE LEACHING
One of the facilities surveyed reported the practice of leaching
and rinsing a portion of the molybdenite concentrate raw material
prior to roasting. The concentrate is leached with nitric acid
and rinsed with water to remove excess alkali. The leachate and
rinsewater are then discharged as a wastewater stream. This
waste stream has an acidic pH, and treatable levels of toxic
metals and suspended solids. The one facility which reported
this waste stream discharges it to an on-site evaporation pond
and contract hauls a portion of the contents of the pond period-
ically, thereby achieving zero discharge.
ROASTER S0£ SCRUBBER
Four facilities reported the use of caustic scrubbers to control
S02 emissions from molybdenum sulfide roasting operations. The
blowdown from the caustic scrubber has an alkaline pH, and treat-
able concentrations of suspended solids and toxic metals. All
four facilities reporting this waste stream achieve zero dis-
charge through evaporation ponds, lagoon disposal, or treatment
and reuse in other plant processes. The specific practices
reported by the four facilities are:
1. Lime addition and sedimentation, recycle to other plant
processes;
2. Neutralization, permanent lagoon disposal (no recycle);
3. Use as feedstock for fertilizer plant; and
4. Tailings pond (96 percent recycle).
MOLYBDIC OXIDE LEACHATE
Technical grade molybdic oxide may be leached with nitric acid,
aqueous ammonia, and water prior to dissolving and recrystalli-
zation to produce ammonium molybdate. The spent leachate and
rinsewater contain treatable levels of toxic metals, suspended
solids, and ammonia. For the two plants generating this stream,
the reported treatment practices for this waste stream are as
follows:
1. Ammonia steam stripping, lime addition, and sedimenta-
tion; and
2. Evaporation ponds and contract hauling.
HYDROGEN REDUCTION FURNACE SCRUBBER
Hydrogen gas from the reduction furnaces used to produce molybde-
num metal powder may be quenched or scrubbed with water prior to
reuse in the furnaces. Treatable concentrations of toxic metals
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are present in the water discharged from the scrubbing system.
Of the two facilities reporting this wastewater stream, one prac-
tices extensive recycle (>99 percent) and the other practices no
recycle. Both plants are direct dischargers of this waste stream
with no wastewater treatment practiced.
DEPLETED RHENIUM SCRUBBING SOLUTION
Rhenium is absorbed into solution from molybdenite roaster off-
gases in a wet scrubbing system. After the rhenium is recovered
from solution, the barren scrubber liquor is discharged as a
wastewater stream. Treatable concentrations of toxic metals,
particularly selenium, are present in this waste stream. Both of
the facilities reporting this waste stream achieve zero dis-
charge. The specific practices reported by these facilities
are:
1. Lime addition and sedimentation, total reuse in other
plant processes; and
2. Evaporation ponds and contract hauling.
SULFURIC ACID PLANT SLOWDOWN
When a sulfuric acid plant is used to control S02 emissions
from molybdenite roasting operations, a wastewater stream is
generated consisting primarily of blowdown from water scrubbers
which are used to clean the flue gases upstream from the cata-
lytic converters which convert S02 to 803. This wastewater
stream has an acidic pH and treatable concentrations of toxic
metals and suspended solids. Of the three facilities reporting
this waste stream, two reported no recycle and one reported 96
percent recycle. The reported wastewater treatment practices for
this stream are as follows:
1. Lime addition and sedimentation (no recycle),
2. Sulfide precipitation preliminary treatment using H2S
addition, followed by lime addition and sedimentation
(no recycle), and
3. Contract hauling after 96 percent recycle.
CONTROL AND TREATMENT OPTIONS
The Agency examined three control and treatment technology alter-
natives that are applicable to the primary molybdenum and rhenium
subcategory. The options selected for evaluation represent a
combination of in-process flow reduction, pretreatment technology
applicable to individual waste streams, and end-of-pipe treatment
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technologies. Following the discussion of these treatment alter-
natives, the technology basis of the promulgated metallurgical
acid plants subcategory limitations and standards will be
reviewed for the reader's reference. EPA is proposing to expand
the applicability of the promulgated metallurgical acid plants
regulation to include molybdenum sulfuric acid plants. A
detailed discussion of the treatment technology selection for
each regulatory level can be found in the Metallurgical Acid
Plants Subcategory Development Document of the Nonferrous Metals
Manufacturing Point Source Category, Phase I.
OPTION A
The Option A treatment scheme consists of ammonia steam stripping
preliminary treatment applied to molybdic oxide leachate waste-
water. Preliminary treatment is followed by chemical precipita-
tion and sedimentation applied to the combined stream of steam .
stripper effluent, molybdenum sulfide leaching, roaster scrubber,
hydrogen reduction furnace scrubber wastewater, and depleted
rhenium scrubbing solution. Chemical precipitation is used to
remove metals by the addition of lime followed by gravity sedi-
mentation. Suspended solids are removed by this process.
OPTION B
Option B for the primary molybdenum and rhenium subcategory con-
sists of all treatment requirements of Option A (ammonia steam
stripping, chemical precipitation, and sedimentation) plus
control technologies to reduce the discharge of wastewater
volume. Water recycle of hydrogen reduction furnace scrubber
liquor is the principal control mechanism for flow reduction.
OPTION C
Option C for the primary molybdenum and rhenium subcategory con-
sists of all control and treatment requirements of Option B
(ammonia steam stripping, in-process flow reduction, chemical
precipitation, and sedimentation) plus multimedia filtration
technology added at the end of the Option B treatment scheme.
Multimedia filtration is used to remove suspended solids,
including precipitates of metals, beyond the concentration
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 as
well. The addition of filters also provides consistent removal
during periods in which there are rapiu increases in flows or
loadings of pollutants to the treatment system.
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TREATMENT LEVELS FOR METALLURGICAL ACID PLANTS
BPT limitations for metallurgical acid plants are based on chemi-
cal precipitation and sedimentation treatment technology. This
treatment scheme is shown in Figure IX-2.
BAT limitations for metallurgical acid plants are based on in-
process flow reduction, chemical precipitation and sedimentation,
sulfide precipitation and sedimentation, followed by multimedia
filtration for lead and zinc plants (see Figure X-4). For copper
acid plants the BAT treatment technology is based on in-process
flow reduction, sulfide precipitation, pressure filtration,
chemical precipitation, sedimentation, and multimedia filtration
(see Figure X-5). For molybdenum acid plants, the Agency is pro-
posing BAT limitations based on sulfide precipitation and pres-
sure filtration pretreatment, followed by chemical precipitation,
sedimentation, and multimedia filtration as presented in Figure
X-5.
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PRIMARY MOLYBDENUM AND RHENIUM SUBCATEGORY
SECTION VIII
COSTS, ENERGY, AND NONWATER QUALITY ASPECTS
This section presents a summary of compliance costs for the
primary molybdenum and rhenium subcategory and a description of
the treatment options and subcategory-specific assumptions used
to develop these estimates. Together with the estimated pollu-
tant reduction performance presented in Sections IX, X, XI, and
XII of this supplement, these cost estimates provide a basis for
evaluating each regulatory 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, includ-
ing air pollution, solid wastes, and energy requirements, which
are specific to the primary molybdenum and rhenium subcategory.
TREATMENT OPTIONS FOR EXISTING SOURCES
As discussed in Section VII, three treatment options have been
developed for existing primary molybdenum and rhenium sources.
The treatment schemes for each option are summarized below and
schematically presented in Figures X-1 through X-3. The regula-
tory treatment technologies for metallurgical acid plants were
discussed at the end of Section VII of this document. The treat-
ment schemes for the regulatory levels are presented in Figures
IX-2, X-4, and X-5.
OPTION A
Option A consists of ammonia steam stripping preliminary treat-
ment and chemical precipitation and sedimentation end-of-pipe
technology.
OPTION B
Option B consists of in-process flow, reduction measures, ammonia
steam stripping preliminary treatment, and chemical precipitation
and sedimentation end-of-pipe technology. The in-process flow
reduction measure consists of the recycle of hydrogen reduction
furnace scrubber water through holding tanks.
OPTION C
Option C requires the in-process flow reduction measures of
Option B, ammonia steam stripping preliminary treatment, and
end-of-pipe treatment technology consisting of chemical precipi-
tation, sedimentation, and multimedia filtration.
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COST METHODOLOGY
A detailed discussion of the methodology used to develop the
compliance costs is presented in Section VIII of the General
Development Document. Plant-by-plant compliance costs have been
estimated for the nonferrous metals manufacturing category and
are documented in detail in the administrative record supporting
this regulation. The costs developed for the proposed regulation
are presented in Table VIII-1. The estimated costs for metallur-
gical acid plants associated with primary molybdenum operations
are presented in Table VIII-2.
Each of the general assumptions used to develop compliance costs
is presented in Section VIII of the General Development Document.
Each subcategory also contains a unique set of waste streams
requiring certain subcategory-specific assumptions to develop
compliance costs. The major assumptions specific to the primary
molybdenum and rhenium subcategory are discussed briefly below.
(1) The acid plant blowdown waste stream is found in two
of the four plants belonging to this subcategory and
represents the only nonferrous metals phase II waste
stream present. The production normalized regulatory
flows developed under the phase I analysis were used,
although the raw waste characteristics derived from
phase II sampling data were used as the basis for cost
estimation.
(2) Costs for the removal of molybdenum are included in
the treatment system costs. Molybdenum treatment
effectiveness concentrations are estimated to be 1.41
and 0.94 mg/1 for lime and settle and lime, settle and
filter, respectively.
(3) Costs for plants having total flows of less than 100
1/hr were based on the general guidelines established
for low flows. These are discussed in Section VIII of
the General Development Document.
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 for molybdenum sulfuric acid
plants are incorporated inLu the impacts attributed to the pri-
mary molybdenum and rhenium subcategory. These impacts, includ-
ing energy requirements, solid waste, and air pollution are
discussed below.
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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 580,000 kWh/yr. Option B energy requirements decrease
over those for Option A because less water is being treated, thus
saving energy costs for lime and settle treatment. Option C,
which includes filtration, is estimated to increase energy con-
sumption over Option B by approximately 1 percent. Further, the
total energy requirement for Option C is approximately 1 percent
of the estimated total plant energy usage. 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
Sludges associated with the primary molybdenum and rhenium
subcategory will necessarily contain quantities of toxic metal
pollutants. 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. Consequently, sludges generated from
treating primary molybdenum and rhenium wastewater, including
metallurgical acid plants wastewater, are not presently subject
to regulation as hazardous wastes.
The technology basis for the metallurgical acid plants includes
sulfide precipitation for the control of various toxic metals.
The Agency believes sludge generated through sulfide precipita-
tion (and sedimentation or pressure filtration) will be classi-
fied as hazardous under RCRA. The costs of hazardous waste
disposal were considered in the economic analysis for this
subcategory (in spite of the current statutory and regulation
exemption) because sulfide will not form metal hydroxides that
resist leaching. The costs of hazardous waste disposal were
determined to be economically achievable. However, lime sludges
are not expected to be hazardous. This judgement is based on the
results of Extraction Procedure (EP) toxicity tests performed on
similar sludges (toxic metal-bearing sludges) generated by other
industries such as the iron and steel industry. A small amount
of excess lime was added during treatment, and the sludges subse-
quently generated passed the toxicity 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.
If these wastes should be identified or are listed as hazardous,
they will come within the scope of RCRA's "cradle to grave"
hazardous waste management program, requiring regulation from the
89
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point of generation to point of final disposition. EPA's gener-
ator 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 CFR Part 464, 46 FR 2802 (January 12, 1981), and
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 Section 4004 of RCRA. See 44 FR
53438 (September 13, 1979). The Agency has calculated as part of
the costs for wastewater treatment the cost of hauling and dis-
posing of these wastes. For more details, see Section VIII of
the general development document.
It is estimated that 1,052 kkg/yr of sludge will be generated as
a result of these proposed regulations for the primary molybdenum
and rhenium subcategory.
AIR POLLUTION
There is no reason to believe that any substantial air pollution
problems will result from implementation of ammonia steam strip-
ping, chemical precipitation, sedimentation, sulfide precipita-
tion, and multimedia filtration. Ammonia steam stripping yields
an aqueous ammonia product stream. The other technologies trans-
fer pollutants to solid waste and are not likely to transfer
pollutants to air.
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Table VIII-1
COST OF COMPLIANCE FOR THE PRIMARY MOLYBDENUM
AND RHENIUM SUBCATEGORY
DIRECT DISCHARGERS
Compliance costs for this subcategory cannot be presented here
because the data on which they are based have been claimed to be
confidential.
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Table VIII-2
COST OF COMPLIANCE FOR METALLURGICAL ACID PLANTS
ASSOCIATED WITH PRIMARY MOLYBDENUM OPERATIONS
DIRECT DISCHARGERS
Compliance costs for this subcategory cannot be presented here
because the data on which they are based have been claimed to be
confidential.
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PRIMARY MOLYBDENUM AND RHENIUM 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)(1)(A). BPT reflects
the existing performance by plants of various sizes, ages, and
manufacturing processes within the primary molybdenum and rhenium
subcategory, as well as the established performance of the recom-
mended BPT systems. Particular consideration is given to the
treatment already in place at existing plants.
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 transferable,
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 wastewaters generated, and the treatment
processes installed. Information was collected from the category
using data collection portfolios, and specific plants were sam-
pled and the wastewaters analyzed. In making technical assess-
ments of data, reviewing manufacturing processes, and assessing
wastewater treatment technology options, both indirect and direct
dischargers have been considered as a single group. An examina-
tion of plants and processes did not, indicate any process differ-
ences based on the type of discharge, whether it be direct or
indirect.
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As explained in Section IV, the primary molybdenum and rhenium
subcategory has been subdivided into six 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
six 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 specif-
ic flow rates generated for each subdivision, and (3) the specif-
ic production normalized flows for each subdivision. This analy-
sis is discussed in detail in Section V. Nonprocess wastewaters
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, the current control
and treatment technologies consist of chemical precipitation and
sedimentation (lime and settle technology) and a combination of
reuse and recycle to reduce flow. Ammonia steam stripping is
applied to streams with treatable concentrations of ammonia.
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
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BPT level of treatment technology (mg/1) for each pollutant
parameter to be limited under BPT. These mass loadings are
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 efflu-
ent limitations for these combined wastewaters are based on the
various wastewater sources which actually contribute to the com-
bined flow. This method accounts for the variety of combinations
of wastewater sources and production processes which may be found
at primary molybdenum and rhenium 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 benefits, EPA
considers the volume and nature of existing discharges, the vol-
ume 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. Tables X-2 and
X-3 show the estimated pollutant removal estimates for each
treatment option for direct dischargers. Compliance costs for
each option are presented in Table X-4 and X-5.
BPT OPTION SELECTION
The technology basis for the proposed BPT limitations is chemi-
cal precipitation and sedimentation technology to remove metals
95
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and solids from combined wastewaters and to control pH, and
ammonia steam stripping preliminary treatment. These technolo-
gies are already in-place at one of the two dischargers in the
subcategory. The other two direct dischargers in the subcategory
discharge only metallurgical acid plant blowdown. The BPT
limitations for these plants are discussed below. The best
practicable technology is presented in Figure IX-1. The BPT
treatment is equivalent to Option A described in Section VII.
Ammonia steam stripping is demonstrated at seven facilities in
the nonferrous metals manufacturing category. These facilities
are treating ammonia bearing wastewaters associated with the
production of primary tungsten, primary columbium and tantalum,
primary molybdenum, secondary tungsten and cobalt, secondary
molybdenum and vanadium, and primary zirconium and hafnium. EPA
believes that performance data from the iron and steel manufac-
turing category provide a valid measure of this technology's
performance on nonferrous metals manufacturing category waste-
water because raw wastewater concentrations of ammonia are of the
same order of magnitude in the respective raw wastewater
matrices.
Chemical analysis data were collected of raw waste (treatment
influent) and treated waste (treatment effluent) from one coke
plant of the iron and steel manufacturing category. A contractor
for EPA, using EPA sampling and chemical analysis protocols,
collected six paired samples in a two-month period. These data
are the data base for determining the effectiveness of ammonia
steam stripping technology and are contained within the public
record supporting this document. Ammonia treatment at this coke
plant consisted of two steam stripping columns in series with.
steam injected countercurrently to the flow of the wastewater. A
lime reactor for pH adjustment separated the two stripping
columns.
The Agency has verified the proposed steam stripping performance
values using steam stripping data collected at a zirconium-
hafnium plant, which has raw ammonia levels as high as any in the
nonferrous metals manufacturing category. Data collected by the
plant represent almost two years of daily operations, and support
the long-term mean used to establish treatment effectiveness.
Implementation of the proposed BPT limitations will remove annu-
ally an estimated 73,631 kg of toxic metals, 1,049 kg of molyb-
denum, 62,813 kg of ammonia, and 51,529 kg of TSS over estimated
current discharge. While both discharging plants have the equip-
ment" in-place to comply with BPT, we do not believe that the
plants are currently achieving the BPT mass limitations. The
estimated capital and annual cost for achieving the proposed BPT
cannot be presented here because the data on which they are based
have been claimed to be confidential.
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More stringent technology options were not selected for BPT since
they require in-process changes or end-of-pipe technologies less
widely practiced in the subcategory, and, therefore, are more
appropriately considered under BAT.
We are expanding the applicability of the existing BPT require-
ments for the metallurgical acid plants subcategory to include
acid plants associated with primary molybdenum roasting opera-
tions. The technology basis for the existing BPT limitations is
chemical precipitation and sedimentation technology to remove
metals and solids from combined wastewaters and to control pH.
These technologies are already in-place at both of the discharg-
ers included under the expanded applicability. The pollutants
specifically proposed for regulation at BPT are cadmium, copper,
lead, zinc, TSS, and pH. The BPT treatment scheme for
metallurgical acid plants is presented in Figure IX-2.
Compliance with the existing BPT limitations for metallurgical
acid plants by the two direct discharging primary molybdenum
facilities which operate sulfuric acid plants will result in the
removal of an estimated 8,026 kg of toxic metals, 381 kg of
molybdenum, and 10,908 kg of TSS annually over estimated current
discharge. While both plants have the equipment in-place to
comply with BPT, we do not believe that the plants are currently
achieving the BPT limitations. The estimated capital and annual
cost for achieving BPT cannot be presented here because the data
on which they are based have been claimed to be confidential.
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 dcp. The discharge rate is used with the
achievable treatment concentration to determine BPT effluent
limitations. Since the discharge rate may be different for each
wastewater source, separate production normalized discharge rates
for each of the six wastewater sources are discussed 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 the product which is produced by the process asso-
ciated with the waste stream in question. These production
normalizing parameters, or PNPs, are 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.
MOLYBDENUM SULFIDE LEACHING
The BPT wastewater discharge rate for molybdenum sulfide leaching
is 463 1/kkg (112 gal/ton) of molybdenum sulfide concentrate
97
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leached prior to roasting. This rate is allocated only to facil-
ities which leach molybdenum sulfide concentrates to remove
excess alkali, prior to roasting. One of the seven plants which
roasts molybdenite practices leaching prior to roasting. The
water use and discharge rate are presented in Table V-1. This
facility currently achieves zero discharge of this stream through
the use of evaporation ponds and contract hauling. The possibil-
ity for achieving zero discharge of this stream in this manner is
site-specific and therefore not applicable on a nationwide basis.
The leaching and rinsing flow reported by this facility was used
as the basis for the BPT flow allowance for this stream.
ROASTER S0£ SCRUBBER
The BPT wastewater discharge rate for molybdenite roaster S02
scrubber wastewater is 1,679 1/kkg (404 gal/ton) of molybdenum
sulfide roasted. This rate is allocated only to those plants
which use scrubbers to control S02 emissions from molybdenum
sulfide roaster flue gases. Four of the seven plants which roast
molybdenum sulfide concentrates use scrubbers to control S02
emissions. Three of these facilities use caustic scrubbers and
achieve zero discharge through the use of tailings ponds or per-
manent impoundments. One facility uses an ammonia scrubbing
solution and achieves zero discharge by using the scrubber liquor
as feed material to a fertilizer plant. One of the four facili-
ties did not report actual flow rates for this stream. The BPT
flow rate was based on the production normalized flows from two
facilities which reported flow rates for scrubbing systems. The
production normalized flow reported by plant 1174 was not used
because the reported water use was inordinately high, and not
characteristic of effective wet air pollution control systems.
MOLYBDIC OXIDE LEACHATE
The BPT wastewater discharge rate for molybdic oxide leachate is
7,630 1/kkg (1,828 gal/ton) of ammonium molybdate product. This
rate is applicable only to those plants which produce ammonium
molybdate through leaching and dissolving molybdic oxide, and
crystallizing ammonium molybdate product. Three of the seven
plants which produce technical grade molybdic oxide also produce
ammonium molybdate. The water use and discharge rates for two of
the facilities are presented in Table V-3. The remaining plant
which produces ammonium molybdate uses an evaporator in the pro-
cess and generates no wastewater. A representative for the
facility, however, indicated that they plan to change from the
evaporative process and will need to discharge wastewater in the
near future. The BPT regulatory flow was based on the average
production normalized water use of the two plants which reported
discharging this wastewater. One of the two plants which
generates process wastewater from the ammonium molybdate process
98
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achieves zero discharge through the use of an evaporation pond
and contract hauling. The possibility for achieving zero
discharge in this manner is site-specific and therefore not
applicable on a nationwide basis.
HYDROGEN REDUCTION FURNACE SCRUBBER
The BPT wastewater discharge rate for reduction furnace hydrogen
scrubbing is 22,898 1/kkg (5,505 gal/ton) of molybdenum metal
powder produced. This rate is applicable only to those plants
which practice wet scrubbing of hydrogen gas used in reduction
furnaces. Two of the four plants which use reduction furnaces to
produce molybdenum metal powder from either pure molybdic oxide
or ammonium molybdate reported the use of wet scrubbing. The
water use and discharge rates are presented in Table V-4. The
BPT flow rate is based on the average of the water use at these
two facilities. One of the facilities reported 0 percent recy-
cle. The other facility reported recycle but did not specify the
recycle ratio. The recycle ratio at this facility was assumed to
be 99 percent and the water use was calculated from the discharge
rate by dividing the discharge flow by 0.01, yielding a water use
of 2,000 1/kkg. The water use and discharge flow rates for the
facility which practices no recycle are the same. This facility
reported a reduction furnace scrubber flow rate of 43,795 1/kkg.
The BPT flow rate is based on the average of the water use rates
at these two facilities.
DEPLETED RHENIUM SCRUBBING SOLUTION
The BPT wastewater discharge rate for depleted rhenium scrubbing
solution is 716 1/kkg (173 gal/ton) of molybdenum sulfide
roasted. This rate is applicable only to those facilities which
recover crude ammonium perrhenate from molybdenite roaster flue
gases. Two of the seven plants which roast molybdenite concen-
trates reported that they recover rhenium from roaster flue
gases. The water use and discharge rates are presented in Table
V-5. Both of the facilities which practice rhenium recovery
achieve zero discharge through the use of evaporation ponds, con-
tract hauling or recycle to other plant processes. The possibil-
ity of achieving zero discharge in this manner is site-specific
and therefore not applicable on a nationwide basis. The BPT flow
rate is based on the average of the production normalized water
use rates reported by the two facilities reporting this stream.
The production normalized flow rates used in the average are 637
1/kkg and 794 1/kkg.
SULFURIC ACID PLANT SLOWDOWN
EPA promulgated best practicable control technology currently
available (BPT) effluent limitations guidelines for the metal-
lurgical acid plants subcategory of the nonferrous metals manu-
facturing category on July 2, 1980. The BPT wastewater flow rate
99
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was determined to be 6,079 1/kkg (1,457 gal/ton) of 100 percent
equivalent sulfuric acid capacity. EPA is presently expanding
the applicability of this regulation to encompass the molybdenum
sulfuric acid plants. Table V-6 shows the production normalized
flows reported for the three plants in the primary molybdenum and
rhenium subcategory that report a sulfuic acid plant blowdown
waste stream. It is noted that the promulgated BPT regulatory
flow is greater than any of the reported production normalized
flows.
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
was presented in Section VI. A total of eight pollutants or pol-
lutant parameters were selected for limitation and are listed
below:
115. arsenic
122. lead
124. nickel
125. selenium
ammonia
fluoride*
molybdenum
total suspended solids
pH
The regulated pollutant parameters for metallurgical acid plants
are listed below:
118. cadmium
120. copper
122. lead
128. zinc
fluoride*
total suspended solids
pH
*The Agency is considering limiting the pollutant fluoride in
this subcategory and is soliciting comments from the industry.
Effluent limitations for fluoride would be based on treatment
effectiveness concentrations of 19.9 mg/1 for the monthly
average and 35 mg/1 for the daily maximum. A complete discus-
sion of fluoride may be found in Section VII of the General
Development Document under treatment performances of additional
pollutants. The treatment effectiveness of fluoride is based on
data from the Electrical and Electronic Components Phase II
Category.
100
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EFFLUENT LIMITATIONS
The treatability concentrations achievable by application of the
proposed BPT treatment are explained in Section VII of the Gen-
eral Development Document and summarized there in Table VI1-19.
The achievable treatment concentrations (both one day maximum and
monthly average values) are multiplied by the BPT normalized dis-
charge 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.
The BPT effluent limitations for metallurgical acid plants are
presented in Table IX-3.
101
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Table IX-2
BPT MASS LIMITATIONS FOR THE
PRIMARY MOLYBDENUM AND RHENIUM SUBCATEGORY
(a) Molybdenum Sulfide Leaching
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of molybdenum sulfide leached
Arsenic 0.968 0.431
Lead 0.195 0.093
Nickel 0.889 0.588
Selenium 0.570 0.255
Molybdenum 2.676 1.190
Ammonia (as N) 61.720 27.130
Total suspended 18.990 9.029
solids
pH Within the range of 7.5 to 10.0
at all times
(b) Roaster S02 Scrubber
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of molybdenum sulfide roasted
Arsenic 3.509 1.561
Lead 0.705 0.336
Nickel 3.224 2.133
Selenium 2.065 0.924
Molybdenum 9.705 4.315
Ammonia (as N) 223.800 98.390
Total suspended 68.840 32.740
solids
pH Within the range of 7.5 to 10.0
at all times
103
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Table IX-2 (Continued)
BPT MASS LIMITATIONS FOR THE
PRIMARY MOLYBDENUM AND RHENIUM SUBCATEGORY
(c) Molybdic Oxide Leachate
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
rog/kg (Ib/million Ibs) of ammonium molybdate
produced
Arsenic 15.950 7.096
Lead 2.983 1.421
Nickel 13.640 9.020
Selenium 8.736 3.906
Molybdenum 44.100 19.610
Ammonia (as N) 1,017.000 447.100
Total suspended 291.200 138.500
solids
pH Within the range of 7.5 to 10.0
at all times
(d) Hydrogen Reduction Furnace Scrubber
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of molybdenum metal powder
produced
Arsenic 47.860 21.300
Lead 9.617 4.580
Nickel 43.970 29.080
Selenium 28.170 12.600
Molybdenum 132.400 58.850
Ammonia (as N) 3,052.000 1,342.000
Total suspended 938.800 446.500
solids
pH Within the range of 7.5 to 10.0
at all times
104
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Table IX-2 (Continued)
BPT MASS LIMITATIONS FOR THE
PRIMARY MOLYBDENUM AND RHENIUM SUBCATEGORY
(e) Depleted Rhenium Scrubbing Solution
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of molybdenum sulfide roasted
Arsenic 1.497 0.666
Lead 0.301 0.143
Nickel 1.375 0.909
Selenium 0.881 0.394
Molybdenum 4.138 1.840
Ammonia (as N) 95.440 41.960
Total suspended 29.360 13.960
solids
pH Within the range of 7.5 to 10.0
at all times
105
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Table IX-3
BPT EFFLUENT LIMITATIONS FOR METALLURGICAL ACID PLANTS
Effluent Characteristic
Effluent Limitations
Maximum for
any 1 day
Average of
daily values
for 30
consecutive
days shall
not exceed
Total suspended solids
Copper
Cadmium
Lead
Zinc
pH
Metric units, kg/kkg of product
English units, pounds per
1,000 pounds of product
0.304
0.005
0.00018
0.0018
0.0036
0.152
0.002
0.00009
0.00079
0.0009
1 Within the range of 6.0 to 9.0
106
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PRIMARY MOLYBDENUM AND RHENIUM 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 manufacturing 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 technology represents the best available technology at plants
of various ages, sizes, processes, or other characteristics. As
with BPT, 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 statutory assessment of BAT considers costs, but does not
require a balancing of costs against pollutant removal benefits
(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 selected
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 three technol-
ogy options which could be applied to the primary molybdenum and
rhenium subcategory as treatment options 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
109
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Section IX for BPT limitations development. The differences in
the mass loadings for BPT and BAT are due to increased treatment
effectiveness achievable with the more sophisticated BAT treat-
ment technology and reductions in the effluent flows usually
achieved by recycle and reuse technologies.
In summary, the treatment technologies considered for BAT are
presented below:
Option A (Figure X-1) is based on
• Preliminary treatment with ammonia steam stripping
• Chemical precipitation and sedimentation
Option B (Figure X-2) is based on
• Preliminary treatment with ammonia steam stripping
• Chemical precipitation and sedimentation
• In-process flow reduction
Option C (Figure X-3) is based on
• Preliminary treatment with ammonia steam stripping
• Chemical precipitation and sedimentation
• In-process flow reduction
• Multimedia filtration
The promulgated treatment technologies for the metallurgical acid
plants are presented below for BAT (Figure X-5):
• Preliminary treatment with sulfide precipitation and
pressure filtration
• Chemical precipitation and sedimentation
• In-process flow reduction
• Multimedia filtration
The three options examined for BAT and the promulgated BAT
treatment technologies for metallurgical acid plants are dis-
cussed in greater detail below. The first option considered is
the same as the BPT treatment which was presented in the previous
section. The last two options each represent substantial
progress toward the prevention of polluting the environment above
and beyond the progress achievable by BPT.
OPTION A
Option A for the primary molybdenum and rhenium subcategory is
equivalent to the control and treatment technologies which were
analyzed for BPT in Section IX. The BPT end-of-pipe treatment
scheme includes chemical precipitation, sedimentation, with
no
-------
ammonia steam stripping preliminary treatment (see Figure X-1).
The discharge rates for Option A are equal to the discharge rates
allocated to each stream as a BPT discharge flow.
OPTION B
Option B for the primary molybdenum and rhenium subcategory
achieves lower pollutant discharge by building upon the Option A
end-of-pipe treatment technology, which consists of ammonia steam
stripping, chemical precipitation, and sedimentation. Flow
reduction measures are added to Option A treatment (see Figure
X-2). These flow reduction measures, including in-process
changes, result in the elimination of some wastewater streams and
the concentration of pollutants in other effluents. Treatment of
a more concentrated effluent allows achievement of a greater net
pollutant removal and introduces the possible economic benefits
associated with treating a lower volume of wastewater.
The method used in Option B to reduce process wastewater genera-
tion or discharge rates is recycle of water used in wet air pol-
lution control. There are two wastewater sources associated with
wet air pollution control or gas cleaning and quenching prior to
recycle which are regulated under these effluent limitations:
--Roaster S02 scrubber, and
--Hydrogen reduction furnace scrubber.
Table X-1 presents the number of plants reporting wastewater use
with these sources, the number of plants practicing recycle of
scrubber water, and the range of recycle values being used.
The BAT regulatory flow for hydrogen reduction furnace scrubbers
is based on recycle of scrubber liquor as discussed later in this
section, and represents the best available technology economi-
cally achievable for this stream. The BAT regulatory flow for
roaster S02 scrubbers will not be flow reduced because the
Agency believes that flow reduction beyond the BPT regulatory
flow is not warranted.
OPTION C
Option C for the primary molybdenum and rhenium subcategory
consists of all control and treatment requirements of Option B
(ammonia steam stripping, in-process flow reduction, chemical
precipitation, and sedimentation) plus multimedia filtration
technology added at the end of the Option B treatment scheme (see
Figure X-3). Multimedia filtration is used to remove suspended
solids, including precipitates of toxic metals, beyond the con-
centrations attainable by gravity sedimentation alone. The
filter suggested is of the gravity, mixed media type, although
1 11
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other filters, such as rapid sand filters or pressure filters,
would perform as well.
METALLURGICAL ACID PLANTS
The promulgated limitations for metallurgical acid plants are
based on in-process flow reduction, chemical precipitation and
sedimentation, sulfide precipitation and sedimentation, followed
by multimedia filtration for lead and zinc acid plants (Figure
X-4). For copper acid plants, the promulgated BAT treatment
technology is based on in-process flow reduction, sulfide precip-
itation, pressure filtration, chemical precipitation and sedimen-
tation, and multimedia filtration (Figure X-5). The Agency is
proposing expanding the metallurgical acid plants BAT limitations
to include molybdenum acid plants based on sulfide precipitation
and pressure filtration pretreatment, followed by chemical pre-
cipitation and sedimentation, and multimedia filtration as
presented in Figure X-5.
INDUSTRY COST AND POLLUTANT REMOVAL ESTIMATES
As one means of evaluating each technology option, EPA developed
estimates of the pollutant removal estimates 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 molybdenum and rhenium subcategory. The pol-
lutant 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 then 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 first comparing the actual discharge to the regulatory
flow. The smaller of the two values was selected and summed with
112
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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 pro-
cess wastewater discharged by the subcategory. Finally, the mass
of pollutant removed is the difference between the estimated mass
of pollutant generated by each plant in the subcategory and the
mass of pollutant discharged after application of the treatment
option. The pollutant removal estimates for direct dischargers
in the primary molybdenum and rhenium subcategory are presented
in Table X-2. The pollutant removal estimates for metallurgical
acid plants associated with primary molybdenum operations are
presented in Table X-3.
COMPLIANCE COST
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 dis-
cussed above, this flow is either the actual or the BAT regula-
tory flow, whichever is lesser. The final step was to annualize
the capital costs, and to sum the annualized capital costs, and
the operating and maintenance costs for each plant, yielding the
cost of compliance for the subcategory (See Table X-4). These
costs were used in assessing economic achievability. The cost of
compliance for metallurgical acid plants associated with primary
molybdenum operations are presented in Table X-5.
BAT OPTION SELECTION
EPA has selected Option C as the basis for BAT in this subcate-
gory. Option C consists of the BPT technology (chemical precipi-
tation and sedimentation), in-process wastewater reduction, and
multimedia filtration. Flow reductions are based on 90 percent
recycle of scrubber liquor, a rate surpassed by one of the two
direct discharger plants.
Implementation of the proposed BAT limitations would remove annu-
ally an estimated 73,655 kg of toxic metals, which is 24 kg of
toxic metals over the estimated BPT discharge. No additional
ammonia is removed at BAT. The estimated capital and annual cost
for achieving proposed BAT cannot be presented here because the
data on which they are based have been claimed to be confiden-
tial.
The intermediate option we considered for BAT is flow reduction
plus the proposed technology basis for BPT. This option would
113
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remove an estimated 13 kg of toxic metals over the estimated BPT
discharge. The estimated capital and annual cost for achieving
this option cannot be presented here because the data on which
they are based have been claimed to be confidential.
We are expanding the applicability of the existing BAT limita-
tions for metallurgical acid plants to include acid plants asso-
ciated with primary molybdenum roasting operations. The existing
promulgated BAT limitations are based on treatment technology
consisting of in-process wastewater reduction, sulfide precipita-
tion preliminary treatment, chemical precipitation and sedimenta-
tion, and multimedia filtration. Flow reductions are based on 90
percent recycle of scrubber liquor. Both of the plants included
under the expanded applicability currently discharge less waste-
water than the BAT flow allowance of 2,554 1/kkg (612.5 gal/ton)
of 100 percent sulfuric acid production capacity.
Compliance with the existing BAT limitations for metallurgical
acid plants by the two direct discharging primary molybdenum
facilities which operate sulfuric acid plants will result in the
annual removal of an estimated 8,245 kg of toxic pollutants,
which is 219 kg of toxic metals over the estimated BPT discharge.
The estimated capital and annual costs for achieving BAT for the
molybdenum acid plants cannot be presented here because the data
on which they are based have been claimed to be confidential.
We are proposing filtration as part of the BAT technology because
this technology is demonstrated in the nonferrous metals manufac-
turing category (25 facilities presently have filters), and
results in additional removals of toxic metals. In addition,
filtration adds reliability to the treatment system by making it
less susceptible to operator error and to sudden changes in raw
wastewater flows and concentrations.
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 dcp. The discharge rate is used with the achievable
treatment concentration to determine BAT effluent limitations.
Since the discharge rate may be different for each wastewater
source, separate production normalized discharge rates for each
of the five wastewater sources were determined and are summarized
in Table X-4. The discharge rates are normalized on a production
basis by relating the amount of wastewater generated to the mass
of the product which is produced by the process associated with
the waste stream in question. These production normalizing para-
meters (PNP) are also listed in Table X-6.
114
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The BAT wastewater discharge rate equals the BPT wastewater dis-
charge rate for four of the six waste streams in the primary
molybdenum and rhenium subcategory. Based on the available data,
the Agency did not find that further flow reduction would be
feasible for these wastewater sources. The rationale for deter-
mining the regulatory flows for these four streams was previously
presented in Section IX. Wastewater streams for which BAT dis-
charge rates differ from BPT are discussed below.
HYDROGEN REDUCTION FURNACE SCRUBBER
The BAT wastewater discharge rate for hydrogen reduction furnace
scrubber water is 2,290 1/kkg (550 gal/ton). This rate is allo-
cated only to those plants which practice water scrubbing of
recirculating hydrogen gas from reduction furnaces. The BAT dis-
charge rate is based on 90 percent recycle of the average water
use of the two plants reporting this stream. One facility cur-
rently practices extensive recycle (assumed to be greater than 99
percent as discussed in Section IX) and the other currently
practices no recycle. Water use and discharge rates are
presented in Table V-4.
SULFURIC ACID PLANT SLOWDOWN
The promulgated BAT wastewater discharge rate for sulfuric acid
plant blowdown wastewater is 2,554 1/kkg (612.5 gallons/ton) of
100 percent sulfuric acid production capacity. This rate, prom-
ulgated on'March 8, 1984, is allocated only to those plants which
use an acid plant to convert S02 gas emissions from the molyb-
denite roaster to sulfuric acid. For a discussion of how the BAT
regulatory flow was determined, refer to the Metallurgical Acid
Plants Subcategory Development Document. The production normal-
ized flows reported by three plants in the primary molybdenum and
rhenium subcategory that have an acid plant blowdown waste stream
are shown in Table V-6. It can be noted that the present dis-
charge rates for these three plants are below the promulgated BAT
regulatory flow for this waste stream.
REGULATED POLLUTANT PARAMETERS
In implementing the terms of the Consent Agreement in NRDC v.
Train, Op. Git., and 33 U.S.C. 1314(b)(2)(A and B) (197^77 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 nine toxic pollutants selected in this
analysis.
115
-------
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 estimate analysis.
The pollutants selected for specific limitation are listed below:
115. arsenic
122. lead
124. nickel
125. selenium
ammonia (as N)
fluoride*
molybdenum
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 mul-
tiple 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.
The toxic metal pollutants selected for specific limitation in
the primary molybdenum and rhenium subcategory to control the
discharges of toxic metal pollutants are arsenic, lead, nickel,
and selenium. Ammonia is also selected for limitation since the
methods used to control the regulated toxic pollutants are not
effective in the control of ammonia. The following toxic pollu-
tants are excluded from limitation on the basis that they are
effectively controlled by the limitations developed for arsenic,
lead, nickel, and selenium:
119. chromium (Total)
120. copper
128. zinc
The regulated pollutants for the metallurgical acid plants are
listed below:
116
-------
115. arsenic
118. cadmium
120. copper
122. lead
128. zinc
fluoride*
*The Agency is considering limiting the pollutant fluoride in
this subcategory and is soliciting comments from the industry.
Effluent limitations for fluoride would be based on treatment
effectiveness concentrations of 19.9 mg/1 for the monthly aver-
age and 35 mg/1 for the daily maximum. A complete discussion
of fluoride may be found in Section VII of the General Develop-
ment Document under treatment performances of additional pollu-
tants. The treatment effectiveness of fluoride is based on data
from the Electrical and Electronic Components Phase II Category.
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 treatability concentrations including
both one day maximum and monthly average values are multiplied by
the BAT normalized discharge flows summarized in Table X-6 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-7 for each waste stream.
The BAT limitations for metallurgical acid plants are presented
in Table X-8.
117
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Table X-4
COST OF COMPLIANCE FOR THE
PRIMARY MOLYBDENUM AND RHENIUM SUBCATEGORY
DIRECT DISCHARGERS
The compliance costs for this subcategory cannot be presented
here because the data on which they are based have been claimed
to be confidential.
121
-------
Table X-5
COST OF COMPLIANCE FOR METALLURGICAL ACID PLANTS
ASSOCIATED WITH PRIMARY MOLYBDENUM OPERATIONS
DIRECT DISCHARGERS
The compliance costs for this subcategory cannot be presented
here because the data on which they are based have been claimed
to be confidential.
122
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Table X-7
BAT MASS LIMITATIONS FOR THE
PRIMARY MOLYBDENUM AND RHENIUM SUBCATEGORY
(a) Molybdenum Sulfide Leaching
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of molybdenum sulfide leached
Arsenic 0.644 0.287
Lead 0.130 0.060
Nickel 0.255 0.171
Selenium 0.380 0.171
Molybdenum 1.783 0.792
Ammonia (as N) 61.720 27.130
(b) Roaster S02 Scrubber
Pollutant or Maximum for Maximum for
Pollutant Property Any One Da.y Monthly Average
mg/kg (Ib/million Ibs) of molybdenum sulfide roasted
Arsenic 2.334 1.041
Lead 0.470 0.218
Nickel 0.924 0.621
Selenium 1.377 0.621
Molybdenum 6.464 2.871
Ammonia (as N) 223.800 93.390
(c) Molybdic Oxide Leachate
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of ammonium molybdate
produced
Arsenic 10.610 4.731
Lead 1.989 0.923
Nickel 3.906 2.628
Selenium 5.824 2.628
Molybdenum 29.380 13.050
Ammonia (as N) 1,017.000 447.100
124
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Table X-7 (Continued)
BAT MASS LIMITATIONS FOR THE
PRIMARY MOLYBDENUM AND RHENIUM SUBCATEGORY
(d) Hydrogen Reduction Furnace Scrubber
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of molybdenum metal powder
produced
Arsenic 3.183 1.420
Lead 0.641 0.298
Nickel 1.260 0.847
Selenium 1.878 0.847
Molybdenum 8.817 3.916
Ammonia (as N) 305.300 134.200
(e) Depleted Rhenium Scrubbing Solution
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of molybdenum sulfide roasted
Arsenic 0.995 0.444
Lead 0.201 0.093
Nickel 0.394 0.265
Selenium 0.587 0.265
Molybdenum 2.757 1.224
Ammonia (as N) 95.440 41.960
125
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Table X-8
BAT EFFLUENT LIMITATIONS FOR METALLURGICAL ACID PLANTS
Pollutant or pollutant property
BAT Effluent Limitations
Maximum
for any
1 day
Maximum
for monthly
average
(Mg/kg pounds per million
pounds) of 100 pet sulfuric
acid capacity
Cadmium
3.550
.51 1
3.269
.715
2.605
1 .456
.204
1 .558
.332
1 .073
126
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PRIMARY MOLYBDENUM AND RHENIUM SUBCATEGORY
SECTION XI
NEW SOURCE PERFORMANCE STANDARDS
The basis for new source performance standards (NSPS) under
Section 306 of the Act is the best available demonstrated tech-
nology (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,
Congress 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 molybdenum and
rhenium subcategory, 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
primary molybdenum and rhenium plants. This result is a conse-
quence of careful review by the Agency of a wide range of tech-
nical options for new source treatment systems which is discussed
in Section XI of the General Development Document. This review
of the primary molybdenum and rhenium subcategory found no new,
economically feasible, demonstrated 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 characteristics 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. For metallurgical acid plants, the promulgated
limitations and standards include NSPS equal to BAT. Since EPA
is proposing to expand the applicability of the metallurgical
acid plants regulation to include molybdenum acid plants, the
standards for new source molybdenum acid plants are equal to
those for BAT. Consequently, 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
identical to the treatment technologies considered for the BAT
options. These options are:
133
-------
OPTION A
• Preliminary treatment with ammonia steam stripping
(where required)
• Chemical precipitation and sedimentation
OPTION B
• Preliminary treatment with ammonia steam stripping
(where required)
• Chemical precipitation and sedimentation
• In-process flow reduction of hydrogen reduction furnace
scrubber liquor
OPTION C
• Preliminary treatment with ammonia steam stripping
(where required)
• Chemical precipitation and sedimentation
• In-process flow reduction of hydrogen reduction furnace
scrubber liquor
• Multimedia filtration
The promulgated treatment technologies for the metallurgical acid
plants are presented below for NSPS:
• Preliminary treatment with sulfide precipitation and
pressure filtration
• Chemical precipitation and sedimentation
• In-process flow reduction
• Multimedia filtration
NSPS OPTION SELECTION
We are proposing that NSPS be equal to BAT. Our review of the
industry indicates that no new demonstrated technologies that
improve on BAT technology exist.
The wastewater flow rates for NSPS are the same as the BAT flow
rates because we do not believe that new plants could achieve any
additional flow reduction beyond the 90 percent scrubber effluent
recycle proposed for BAT.
We are expanding the applicability of the existing NSPS regula-
tion for the metallurgical acid plants subcategory to include
acid plants associated with primary molybdenum roasting
operations.
134
-------
REGULATED POLLUTANT PARAMETERS
The Agency has no reason to believe that the pollutants that will
be found in treatable concentrations in processes 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
Sections VI and X, are identical to those selected for BAT. The
conventional pollutant parameters TSS and pH are also selected
for limitation. The Agency is considering limiting the pollutant
fluoride in this subcategory and is soliciting comments from the
industry. Effluent limitations for fluoride would be based on
treatment effectiveness concentrations of 19.9 mg/1 for the
monthly average and 35 mg/1 for the daily maximum. A complete
discussion of fluoride may be found in Section VII of the General
Development Document under treatment performances of additional
pollutants. The treatment effectiveness of fluoride is based on
data from the Electrical and Electronic Components Phase II
Category.
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
calculated by multiplying the appropriate treatable concentration
(mg/1) by the production normalized wastewater discharge flows
(1/kkg). The treatable concentrations are listed in Table VI1-19
of the General Development Document. The results of these calcu-
lations are the production-based new source performance stan-
dards. These standards are presented in Table XI-2. The new
source performance standards for metallurgical acid plants are
presented in Table XI-3.
135
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Table XI-2
NSPS FOR THE PRIMARY MOLYBDENUM AND
RHENIUM SUBCATEGORY
(a) Molybdenum Sulfide Leaching
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of molybdenum sulfide leached
Arsenic 0.644 0.287
Lead 0.130 0.060
Nickel 0.255 0.171
Selenium 0.380 0.171
Molybdenum 1.783 0.792
Ammonia (as N) 61.720 27.130
Total suspended 6.945 5.556
solids
pH Within the range of 7.5 to 10.0
at all times
(b) Roaster S02 Scrubber
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of molybdenum sulfide roasted
Arsenic 2.334 1.041
Lead 0.470 0.218
Nickel 0.924 0.621
Selenium 1.377 0.621
Molybdenum 6.464 2.871
Ammonia (as N) 223.800 98.390
Total suspended 25.180 20.140
solids
pH Within the range of 7.5 to 10.0
at all times
137
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Table XI-2 (Continued)
NSPS FOR THE PRIMARY MOLYBDENUM AND
RHENIUM SUBCATEGORY
(c) Molybdic Oxide Leachate
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of ammonium molybdate
produced
Arsenic 10.610 4.731
Lead 1.989 0.923
Nickel 3.906 2.628
Selenium 5.824 2.628
Molybdenum 29.380 13.050
Ammonia (as N) 1,017.000 447.100
Total suspended 106.600 85.230
solids
pH Within the range of 7.5 to 10.0
at all times
(d) Hydrogen Reduction Furnace Scrubber
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of molybdenum metal powder
produced
Arsenic 3.183 1.420
Lead 0.641 0.298
Nickel 1.260 0.847
Selenium 1.878 0.847
Molybdenum 8.817 3.916
Ammonia (as N) 305.300 134.200
Total suspended 34.350 27.480
solids
pH Within the range of 7.5 to 10.0
at all times
38
-------
Table XI-2 (Continued)
NSPS FOR THE PRIMARY MOLYBDENUM AND
RHENIUM SUBCATEGORY
(e) Depleted Rhenium Scrubbing Solution
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of molybdenum sulfide roasted
Arsenic 0.995 0.444
Lead 0.201 0.093
Nickel 0.394 0.265
Selenium 0.587 0.265
Molybdenum 2.757 1.224
Ammonia (as N) 94.440 41.960
Total suspended 10.740 8.592
solids
pH Within the range of 7.5 to 10.0
at all times
139
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Table XI-3
NSPS FOR METALLURGICAL ACID PLANTS
Pollutant or pollutant property
NSPS
Maximum
for any
1 day
Maximum
for monthly
average
(Mg/kg pounds per million
pounds) of 100 pet sulfuric
acid capacity
Arsenic ,
Cadm ium
Copper ,
Lead ,
Zinc
Total suspended solids,
pH
3.550
.511
3.269
.715
2.605
38.310
1 .456
.204
1 .558
.332
1 .073
30.650
1 Within the range of 7.0 to 10.0 at all times
-------
PRIMARY MOLYBDENUM AND RHENIUM 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, including 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.
EPA is not proposing pretreatment standards for existing sources
at this time because there are currently no indirect discharging
facilities in this subcategory.
This section describes the control and treatment technologies for
pretreatment of process wastewaters from new sources in the pri-
mary molybdenum and rhenium subcategory. Pretreatment standards
for regulated pollutants are presented based on the selected
control and treatment 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
treatment requirements, is less than the percentage removed by
141
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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. Similarly, the treatment tech-
nologies proposed for the expanded applicability of the metallur-
gical acid plants regulation to include pretreatment standards
for new source molybdenum acid plants are the same as those for
BAT.
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
• Preliminary treatment with ammonia steam stripping
(where required)
• Chemical precipitation and sedimentation
OPTION B
• Preliminary treatment with ammonia steam stripping
(where required)
• Chemical precipitation and sedimentation
• In-process flow reduction of hydrogen furnace reduction
scrubber liquor
142
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OPTION C
• Preliminary treatment with ammonia steam stripping
(where required)
• Chemical precipitation and sedimentation
• In-process flow reduction of hydrogen furnace reduction
scrubber liquor
• Multimedia filtration
The promulgated treatment technologies for the metallurgical acid
plants are presented below for PSNS:
• Preliminary treatment with sulfide precipitation and
pressure filtration
• Chemical precipitation and sedimentation
• In-process flow reduction
• Multimedia filtration
PSNS OPTION SELECTION
We are proposing PSNS equal to NSPS and BAT for this subcategory.
It is necessary to propose PSNS to prevent pass-through of
arsenic, lead, nickel, selenium, molybdenum and ammonia. These
toxic pollutants are removed by a well-operated POTW achieving
secondary treatment at an average of 13 percent, while the NSPS
and BAT level technology removes approximately 79 percent.
We are proposing to expand the applicability of the existing PSNS
for metallurgical acid plants to include metallurgical acid
plants associated with primary molybdenum roasters. It is neces-
sary to propose PSNS to prevent pass-through of arsenic, cadmium,
copper, lead and zinc. These toxic pollutants are removed by a
well-operated POTW achieving secondary treatment at an average of
42 percent, while BAT level technology removes approximately 83
percent.
We believe that the proposed PSNS are achievable, and that they
are not a barrier to entry of new plants into this subcategory.
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.
REGULATED POLLUTANT PARAMETERS
Pollutants selected for limitation, in accordance with the
rationale of Sections VI and X, are identical to those selected
for limitation for BAT. The Agency is considering limiting the
pollutant fluoride in this subcategory and is soliciting comments
from the industry. Effluent limitations for fluoride would be
based on treatment effectiveness concentrations of 19.9 mg/1 for
143
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the monthly average and 35 mg/1 for the daily maximum. A
complete discussion of fluoride may be found in Section VII of
the General Development Document under treatment performances of
additional pollutants. The treatment effectiveness of fluoride
is based on data from the Electrical and Electronic Components
Phase II Category.
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 are presented in Table XII-2. PSNS
for metallurgical acid plants are presented in Table XII-3.
144
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Table XII-2
PSNS FOR THE PRIMARY MOLYBDENUM
AND RHENIUM SUBCATEGORY
(a) Molybdenum Sulfide Leaching
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of molybdenum sulfide leached
Arsenic 0.644 0.287
Lead 0.130 0.060
Nickel 0.255 0.171
Selenium 0.380 0.171
Molybdenum 1.783 0.792
Ammonia (as N) 61.720 27.130
(b) Roaster S0.2 Scrubber
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of molybdenum sulfide roasted
Arsenic 2.334 1.041
Lead 0.470 0.218
Nickel 0.924 0.621
Selenium 1.377 0.621
Molybdenum 6.464 2.871
Ammonia (as N) 223.800 98.390
(c) Molybdic Oxide Leachate
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of ammonium molybdate
produced
Arsenic 10.610 4.731
Lead 1.989 0.923
Nickel 3.906 2.628
Selenium 5.824 2.628
Molybdenum 29.380 13.050
Ammonia (as N) 1,017.000 447.100
146
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Table XI1-2 (Continued)
PSNS FOR THE PRIMARY MOLYBDENUM
AND RHENIUM SUBCATEGORY
(d) Hydrogen Reduction Furnace Scrubber
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of molybdenum metal powder
produced
Arsenic 3.183 1.420
Lead 0.641 0.298
Nickel 1.260 0.847
Selenium 1.878 0.847
Molybdenum 8.817 3.916
Ammonia (as N) 305.300 134.200
(e) Depleted Rhenium Scrubbing Solution
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of molybdenum sulfide roasted
Arsenic .0.995 0.444
Lead 0.201 0.093
Nickel 0.394 0.265
Selenium 0.587 0.265
Molybdenum 2.757 1.224
Ammonia (as N) 95.440 41.960
147
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Table XII-3
PSNS FOR METALLURGICAL ACID PLANTS
Pollutant or pollutant property
PSNS
Maximum
for any
1 day
Maximum
for monthly
average
(Mg/kg pounds per million
pounds) of 100 percent
sulfuric acid capacity
Z inc
3.550
.51 1
3.269
.715
2.605
1 .456
.204
1 .558
.332
1 .073
148
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PRIMARY MOLYBDENUM AND RHENIUM SUBCATEGORY
SECTION XIII
BEST CONVENTIONAL POLLUTANT CONTROL TECHNOLOGY
EPA is not proposing best conventional pollutant control
technology (BCT) limitations for the primary molybdenum and
rhenium subcategory at this time.
149
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