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274
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SINTERING SUBCATEGORY
SECTION IX
EFFLUENT [QUALITY ATTAINABLE THROUGH THE APPLICATION OF '
THE BEST PRACTICABLE CONTROL TECHNOLOGY CURRENTLY AVAILABLE
The Agency has promulgated effluent limitations for Best Practicable
Control Technology Currently Available (BPT) different than those
originally promulgated in June 19741 for sintering operations. Based
upon the changes in the model treatment system flow rate, these
limitations are also less stringent than those proposed on January 7,
1981 (46 FR 1858). The limitations have been adjusted to accommodate
all sintering wastewater sources. The limitations promulgated in 1974
did not take into account wastewaters from raw material handling air
pollution control systems. As the June 1974 development document2
described the basic methods used in developing the previous effluent
limitations, the intent of this section is to provide substantiation
of the BPT effluent limitations. A review of the treatment processes
and effluent limitations associated with the sintering subcategory
follows.
Identification of BPT
The Agency used the original 1974 BPT model treatment system as the
model treatment system ,for the BPT limitations, (See Figure IX-1).
Suspended solids are removed from process wastewaters by gravity
sedimentation in a thickener. A polymeric flocculant is added to the
thickener influent to optimize the removal of suspended solids. The
thickener underflow is dewatered in a vacuum filter, and the filtrate
returned to the thickener inlet. About 92% of the thickener overflow
is returned to the sintering operation. The pH of the treatment
system blowdown, which is typically alkaline, is adjusted to the
neutral pH range with acid. Oils and greases are removed by surface
skimming in the thickener and also by entrainment within the solids
which settle in the thickener.
As noted previously, the BPT limitations do not require the
installation of the model treatment system. Any treatment system
which achieves compliance with the BPT limitations is appropriate.
JFederal Register; Friday, June 28, 1974; Part II, Environmental
Protection Agency; Iron and Steel Manufacturing Point Source Category;
Effluent Guidelines and Standards; Pages 24114-24133.
2EPA 440/1-74-024-a, Development Document for Effluent Limitations
Guidelines and 'New Source Performance Standards for the Steel Making
Segment of the Iron and Steel Manufacturing Point Source Category.
275
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The BPT limitations are based upon ;the same effluent concentrations
used in developing the originally promulgated limitations and the
limitations proposed on January 7, 1981. These concentrations are
well demonstrated as shown by the data in Table A-6,of Appendix A,
Volume I. However, information received during the comment period
indicates the model effluent flow should be increased from 417 1/kkg
(TOO gal/ton) to 499 1/kkg (120 gal/ton). As the model effluent flow
has been increased, the effluent limitations were also increased
proportionately. The BPT effluent limitations are presented below:
• kg/kkg of Product
'(lb/1000 lb of Product)
Daily Maximum
Limitations
30-Day Average
Limitations
Total Suspended Solids
Oil and Grease
pH (Units)
0.0751
0.0150
0.0250
0.00501
6.0 to 9.0
Rationale for BPT 1
Treatment System
r
As noted in Section VII, the components of the BPT model treatment
system are presently in use at most sintering operations.
i
Model Discharge Flow !
i •
Table IX-1 presents a summary of trie flow, recycle rate, and operating
data for this subcategory. The original model effluent flow was based
upon data from one sintering operation which generates wastewater from
only the discharge end (sinter cooling, crushing, and screening) of
the process. However, since wastewater discharges originate at
several points in the sintering operation (refer to Section III), the
Agency increased the model effluent flow to accomodate all wastewater
sources. The model flow rate of 120 gal/ton represents the average of
those plants (identified by asterisks in Table IX-1) which practice a
high degree of wastewater recycle from the machine end (wind box, raw
mater-ial transfer, etc.). Plants' with recycle rates equal to or
greater than 88% were used in this analysis. The Agency considers
plants with these recycle rates representative of the best plants in
this subcategory. The plants used to develop the model flow rates are
representative of other sintering operations and include wastewaters
from the wind box and other sources. Plant 0060F, at which
wastewaters are recycled and the lowest discharge rate is achieved,
was not included in the development of the model flow rate. The
scrubber system at this plant uses steam and is different than
scrubbers commonly used at sintering operations. The data in Table
IX-1 demonstrate that the model effluent flow of 120 gal/ton is
achieved at several plants including those that recycle wastewaters
from only the discharge end or from both ends of the operation. The
; 276
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Agency believes that the model flow rate can be achieved at all wet
sintering plants by providing or increasing the rate of recycle.
It should be noted that those flows averaged to develop the model
effluent flow are for plants in which process wastewaters are
generated at the machine end of the sintering operation. The
pollutant loads in machine end process wastewaters were typically
found to be greater than the loads in discharge end, both end or
cooling wastewaters (refer to process descriptions in Section III and
to the analytical data in Section VII). Recycle rates and discharge
flows achieved; in systems with more highly contaminated wastewaters
demonstrate the ability of those operations with less contaminated
wastewaters to achieve similar discharge flows and recycle rates
Referring to Table IX-1, applied flows in several instances (discharge
end, both end, or contact cooling) approach or are less than the model
effluent flow. The Agency concludes that the treatment model effluent
flow, and resultant recycle -rate, are well demonstrated in this
subcategory.
Justification of the BPT Effluent Limitations
Table IX-2 presents plant effluent data which support the BPT
limitations. These data show two stand-alone plants in compliance
with the BPT effluent limitations for suspended solids and oil and
grease. The PH at Plant 0396A is higher than the maximum pH
limitation of 9.0 standard units. The pH alone will not affect the
levels of the other BPT limited pollutants and, therefore, has no
bearing on this particular analysis. Several other sintering
operations are in compliance with the BPT effluent limitations. Many
of these (Plants 0060, 0112D, 0448A, 0584C, 0860B, and 0864A) are part
of central treatment systems.
277
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TABLE IX-1
BPT FLOW SUMMARY AND JUSTIFICATION
SINTERING SUBCATEGORY
Plant
Code
0448A
0060F
0868A
0920F*
0396A
0584F
0856Q*
0112B
0920B
0948C*
0112D*
0060
0856F
0432A
0112A
0112C
0584C
0864A
0060B
0492A
0946A
Applied
Flow (gal/ton)
UNK
301
100
: 2124
341
106
2805
133
134
1124
1432
1667
220
245
1604
1292
1368
2819
2186
2582
6605
Discharge
Flow (gal/ton)
. 0
26
70
74
80
106
H7
133
134
135
142
219
220
245
288
793
1368
1733
2186
2582
6605
Operating
Mode
RTP-100
RTP-91
RTP-30
RTP and RUP-94
RTP-75
OT
.RTP-96
OT
OT
RUP-88
RTP-90
RTP and RUP-80
OT
OT
RTP and RUP-77
RTP-39
OT
RTP-38
OT
OT
OT
Origin of Process
Wastewaters Basis
B DCP
A VISIT,:
D DCP ;
A D-DCP
B VISIT'
B ' DCP
A DCP
C DCP
C DCP !
A DCP
A VISIT
C D-DCP
C D-DCP
C VISIT;
B D-DCP
B DCP
A DCP
C D-DCP
C DCP
C DCP
A DCP
A: Front end of operation (e.g., wind box, machine-other than wind box, storage and f
handling area dusts)
B: Discharge end of operation.
C: Both ends of operation.
D: Contact cooling of the product only.
Denotes those plants used to determine the BPT treatment model effluent flow.
average recycle rate of these plants is 92% and the average discharge flow is
117 gal/ton. , I
The
278
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279
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280
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SINTERING SUBCATEGORY
; SECTION X
EFFLUENT QUALITY ATTAINABLE THROUGH
THE APPLICATION OF THE BEST AVAILABLE TECHNOLOGY
ECONOMICALLY ACHIEVABLE
Introduction
The Best Available Technology Economically Achievable (BAT) effluent
limitations are'to be achieved by July 1, 1984. BAT is determined by
reviewing subcategory practices and identifying the best economically
achievable control and treatment technology employed within the
subcategory. In addition, where a treatment technology is readily
transferable from another subcategory or industry, such technology may
be identified as BAT.
This section identifies five BAT treatment alternatives which the
Agency considered for the sintering subcategory. In addition, the
rationale for selecting the BAT model treatment system flow rates and
effluent pollutant concentrations are reviewed. Finally, the
rationale for selecting the BAT model treatment system is discussed,
Identification of BAT
Based upon the information contained in Sections III through VIII, the
following alternative treatment systems were developed to supplement
the BPT model treatment system. These treatment systems are
illustrated schematically in Figure VI.II-1 .
1 .
2.
*
3.
BAT Alternative 1 *
In the first BAT Alternative, the BPT blowdown flow of 120
gal/ton is filtered to reduce the levels of toxic metals and
suspended solids. The pH of the effluent is adjusted using acid.
The pH adjustment step is a BPT component which has been
relocated in the sequence of treatment steps.
BAT Alternative 2
BAT Alternative 2 includes lime precipitation and sedimentation
of the BPT treatment system blowdown for toxic metals control and
subsequent pH control. '
"! ' ' - •
BAT Alternative 3
This alternative includes the treatment system components of BAT
Alternative 2, and adds two-stage (alkaline) chlorination
following clarification for the purpose of oxidizing cyanide,
phenols, and other toxic organic pollutants. The chlorinated
281
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effluent is dechlorinated
prior to discharge.
4. BAT Alternative 4
with an appropriate reducing agent
The fourth BAT alternative
treatment system components of
and adsorption on granular
organic pollutants added as the
discharge.
5. BAT Alternative 5
treatment system includes the
BAT Alternative 3 with filtration
activated carbon for removal of toxic
final treatment steps prior to
In this alternative zero discharge is achieved by evaporating the
BPT treatment system- blowdown and returning all of the condensate
to the process.
Investment and annual costs for the BAT alternative treatment systems
are presented in Section VIII.
Rationale for the Selection of BAT
Treatment Technologies
The model BAT applied and discharge flows are based upon the same
recycle rate (92%) and discharge flciw used to develop the BPT effluent
limitations. Referring to Table IX-1, the average and individual
recycle rates of the plants used to develop the model BAT effluent
flow support a 92% recycle rate. The Agency has included filtration
in some of the model BAT treatment systems to reduce the toxic metal
effluent loads. Removal of toxic metals is'accomplished by removal of
suspended solids, in which the metals are entrained. Three of the 21
"wet" sintering plants are equipped with filtration as part of central
wastewater treatment systems. Filtration is also used extensively in
other steel industry subcategories (e.g., ironmaking, basic oxygen
furnace, continuous casting, and hot forming) and in other industries
for the removal of suspended particulate matter from similar
wastewater streams. • |
•
Lime addition for the purpose of pH adjustment and precipitate
formation is a common wastewater treatment practice. The use of
clarifiers for wastewater sedimentation is common in this subcategory
and in a wide variety of other subcategories and industries.
Two-stage (alkaline) chlorination is included as a means of
controlling cyanide, ammonia-N, and phenols and other toxic organic
pollutants. Alkaline chlorination is practiced at two plants in this*
subcategory as part of co-treatment with blast furnace wastewaters.
Dechlorination using reducing agents is included to control excess
residual chlorine. Dechlorination is practiced at one central
treatment plant which receives sintering process wastewaters.
• 282
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Activated carbon adsorption is included to remove any toxic organic
pollutants which may remain after treatment by alkaline chlorination.
Activated carbon is used in one sinter plant application, where
ironmaking and sintering process wastewaters are co-treated.
Flows
Refer to Table IX-1 for the data used to develop the model BAT
treatment system effluent flow. The plants which have recycle rates
of 90% or more approach or exceed the model BPT recycle rate of 92%.
As noted in Section IX, the Agency believes that a recycle rate of 92%
and a model effluent flow of 120 gal/ton are appropriate for the BAT
model treatment Systems. Aside from the use of vapor compression
distillation, the Agency is not aware of other methods to further
reduce the discharge volume.
Wastewater Quality
Reference is made to-the ironmaking subcategory-report for a complete
discussion of the development of effluent limitations for ammonia-N,
total cyanide, phenols (4AAP), and total residual chlorine applicable
when sintering wastewaters are co-treated with ironmaking wastewaters..
Toxic Metal Pollutants
To determine the effluent concentrations for the toxic metal
pollutants, the Agency evaluated monitoring data from several sources.
The Agency reviewed long-term filtration system effluent data from
similar wastewater treatment applications and pilot treatability study
data to determine the toxic metals removal capabilities of filtration
systems. A review of these data and the monitoring data presented in
Section VII indicate that the toxic metal,s are present in particulate
form. The toxic metals effluent concentrations used to develop the
BAT effluent limitations are the same as those used to establish the
toxic metal limitations for1 ironmaking wastewaters. t These
concentrations are achievable by sintering operations and were used to
facilitate co-treatment with ironmaking wastewaters, a common practice
in the industry. These toxic metals concentrations are support by the
pilot filtration data for plant 0060 presented in Table X-l. Lime
precipitation and sedimentation data from the same source are
presented in Table X-2.
Sulfide addition was considered for treatment of toxic metals.
However, because of the marginal incremental toxic metal removal over
other technologies, and because this technology has not been
demonstrated ,in this subcategory, the Agency did not consider sulfide
precipitation as an alternate BAT technology.
Effluent Limitations for the BAT Alternatives
The effluent limitations associated with the BAT treatment
alternatives were developed on a mass basis (kg/kkg or lb/1000 Ib) by
applying the model plant effluent flow of 120 gal/ton to the
283
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respective BAT treated effluent concentrations of each pollutant. The
effluent limitations for each alternative were established using the
procedures outlined in Volume I. The effluent flow and concentrations
have been previously documented in tjhis section. Table X-3 presents
the effluent limitations developed for each treatment alternative.
The flow and concentration basis for the limitations are also
presented. ;'
Selection of_ a BAT Alternative
The Agency selected BAT Alternative 1 (depicted in Figure X-l) as the
BAT model treatment system. The Agency determined that BAT
Alternative 1 provides significant benefits with regard to reductions
in toxic pollutant effluent loads and should be the BAT model
treatment system. While Alternative 1 is the selected BAT. option, the
Agency believes that Alternative 2 (lime precipitation) can also be
used to achieve the BAT limitations- Except as noted below, the
Agency does not believe that the relatively low levels of ammonia-N,
total cyanide, phenols (4AAP) and other toxic organic pollutants
warrant the application of more advanced technologies including
two-stage alkaline chlorination and'activated carbon to all sintering
plants. Evaporation technology to eliminate the discharge
(Alternative 5), while technically feasible, is extremely costly and
was not selected on that basis.
The Agency recognizes that co-treatment of compatible sintering and
ironmaking wastewaters is practiced at several plants. Accordingly,
the Agency has promulgated effluent limitations for ammonia-N, total
cyanide, phenols (4AAP), and total residual chlorine which are
applicable to sintering wastewaters when these wastewaters are co-
treated with ironmaking wastewaters. The achieveability of these
limitations are demonstrated by the performance at Plant 0860 B which
is discussed in detail in the ironmaking subcategory report. These
sintering BAT limitations are based^upon the model plant effluent data
for sintering and ironmaking operations and the sintering model plant
flow of 120 gal/ton. The promultation of BAT limitations for
ammonia-N, total cyanide, and phenols (4AAP) for sintering operations
is consistent with the Agency's co-treatment .policy. Greater
discharges of toxic and non-conventional pollutants will not result
when these wastewaters are co-treated rather than treated separately.
The levels of these pollutants in BPT treatment system effluents is
close to that found in ironmaking wastewaters after treatment by
alkaline chlorination. : t
The BAT effluent limitations are presented on Table X-3 under the BAT
Alternative 1 heading. The achievability of these limitations is
demonstrated by the performance data developed from the pilot study
and the fact that the model flow rate is well demonstrated. The model
flow rate is the same as the BPT model treatment system flow rate.
Table X-4 justifies the sintering BAT limitations for a sintering
operation co-treated with an ironmaking operation.
284
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BAT Limitations
Sintering sl\
Ironmaking
Total
Current Discharge
of Plant 0860B
TABLE X-4
JUSTIFICATION OF BAT EFFLUENT LIMITATIONS
SINTERING SUBCATEGORY
30-Day ^
Ammonia-N Cyanide
(Ib/day) (Ib/day)
166.3 16.6
120.4 12.0
Average Limitations
Phenols-4AAP Lead
(Ib/day) (Ib/day)
1.7 4.
1.2 3.
2
0
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3.6
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47.4
28.6
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1.4
(1) Sintering Production - 16,600 TPD (from DCP)
Ironmaking Production - 20,611 TPD (from DCP)
(2) Represents activated carbon treatment.
NA: No analyses performed.
288
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290
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SINTERING SUBCATEGORY
SECTION XI
BEST CONVENTIONAL POLLUTANT CONTROL TECHNOLOGY
Introduction
The 1977 Amendments ad'ded Section 301 (b) (2) (E) to*the Act establishing
"best conventional pollutant control technology" (BCT) for discharges
of conventional pollutants from existing industrial point sources.
Conventional pollutants are those defined in Section 304(a)(4)
[biochemical oxygen Demanding pollutants (BOD5), total supended solids
(TSS), fecal coliform, and pH], and any additional pollutants defined
by the Administrator as "conventional" (oil and grease, 44 FR 445Q1,
July 30, 1979). • .
BCT is not an additional limitation but replaces BAT for the control
of conventional pollutants. In addition to other factors specified in
Section 304(b)(4)(B), the Act requires that BCT limitations be
assessed in light of a two part "cost-reasonableness" test. American
Paper Institute v. EPA, 660 F.2d 954 (4th Cir. 1981). The first test
compares the cost for -private industry to reduce its conventional
pollutants with the costs to publicly owned treatment works for
similar levels of reduction in their discharge of these pollutants.
The second test examines the cost-effectiveness of additional
industrial treatment beyond BPT. EPA must find that limitations are
"reasonable" under both tests before establishing them as BCT. In no
case may BCT bfe less stringent than BPT.
.EPA published its methodology for carrying out the BCT analysis on
August 29, 1979 (44 F.R. 50732). In the case mentioned above, the
Court of Appeals ordered EPA to correct data errors underlying EPA's
calculation of the first test, and to apply the second cost test.
(EPA had argued that a second cost test was not required.)
EPA has determined that the BAT technology is capable of removing
significant amounts of conventional pollutants. However, EPA has not
yet proposed or promulgated a revised BCT methodology in response to
the American Paper Institute v. EPA decision mentioned earlier. Thus,
it is not now possible to apply the BCT cost test to this technology
option. Accordingly, EPA is deferring a decision on the appropriate
BCT limitations until EPA proposes the revised BCT methodology.
291'
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6INTERING SUBCATEGORY
SECTION XII
EFFLUENT QUALITY ATTAINABLE THROUGH THE APPLICATION
OF NEW SOURCE PERFORMANCE STANDARDS
Introduction
NSPS are to be established based upon a consideration of the degree of
effluent reduction achievable through . the application of the Best
Available Demonstrated Control Technology (BADCT), processes,
operating methods, or other alternatives including, where practicable,
a standard permitting no discharge of process wastewater pollutants to
navigable waters. The Agency concluded that zero discharge, however,
is not a feasible treatment alternative for "wet" sintering
operations. As discussed in Sections VII and X, there are no
technologies applicable to all sintering operations that would result
in attainment o'f zero discharge in a cost effective manner. Zero
discharge may be achieved at new sintering operations by installing
dry air cleaning systems. However, the Agency did not establish NSPS
on this basis since, in some instances, "wet" air cleaning systems may
be more effective and more appropriate for given applications. NSPS
alternative treatment systems and effluent standards have been
developed to accommodate the use of "wet" air cleaning systems.
Identification and Basis for NSPS
Treatment Scheme and Flow Rates
NSPS Alternative 1
This alternative is identical to BPT and BAT Alternative 1 (refer to
Sections IX and X). This system includes sedimentation of raw process
wastewaters in a thickener in conjunction with the addition of a
flocculant to enhance solids removal. Treatment process sludges are
dewatered by vacuum filtration. Most of the thickener effluent (92%)
is recycled to' the process, while the remaining thickener effluent is
discharged as a blowdown. The recycle blowdown undergoes filtration
to remove toxic metals and suspended solids. Prior to discharge, the
pH of the treated effluent is adjusted, as necessary, to the neutral
range with acid.
NSPS Alternative 2_
This alternative is identical to BPT and BAT Alternative 2. Lime
precipitation and clarification, instead of filtration, of the recycle
system blowdown noted above is included for toxic metals removal.
293
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NSPS Alternative 3_ \
This alternative is identical to BPT and BAT Alternative 3. Two-stage
alkaline chlorination is included in this alternative for the purpose
of cyanide, ammonia and phenol oxidation. Dechlorination is provided
prior to discharge.
NSPS Alternative 4.
This alternative is identical to BPT and BAT Alternative 4, This
alternative provides for the removal, by activated carbon adsorption,
of the remaining toxic organic pollutants that may be present.
NSPS Alternative 5
This alternative is the same as BPT and BAT Alternative 5 and provides
for zero discharge by the use of evaporation technologies.
In order to accommodate process developments which would be included
in the construction of a new source "wet" sintering operation, the
Agency examined various industry trends. In all likelihood, new
sintering operations will have greater production capacities than the
4000 tons/day used for BPT and BAT model treatment systems. The
Agency averaged the production .capacities of sintering operations
constructed in the last decade; and, based upon that average,
established a new source model size of 7,000 tons/day, which was used
for NSPS costing. Although the effluent limitations (kg/kkg of
product) developed for the BAT model treatment systems are the same as
those for the new source systems, the increased model size for new
source operations results in increased treatment model capital and
annual costs due to the increase iiii the volume of wastewater requiring
treatment. A review of the subcategory summary data indicates that
the model BPT and BAT applied and discharge flows are applicable to
new "wet" sintering operations. Trends which might affect flow were
not detected.
F
The NSPS treatment systems described above are depicted in Figure
VIII-1. The corresponding effluent levels and loads are presented in
Table XII-1. Cost data for NSPS are presented in Section VIII.
Rationale for Selection of NSPS ;
The NSPS alternative treatment systems include the same components
described for the BPT and BAT model treatment systems discussed in
Sections IX and X. Reference is made to those sections for a review
of the treatment technologies. |
Selection of -an NSPS Alternative ;
The Agency selected NSPS Alternative 1, depicted in Figure XII-1, as
the NSPS model treatment system. This alternative was selected for
the same reasons noted in Section X regarding the selection of the BAT
294
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model treatment system (i.e., the benefits derived from reduction in
the effluent loads of various pollutants).
The NSPS are presented in Table XII-1 under the heading of NSPS
Alternative 1. As noted in Section X for BAT, NSPS for ammonia-N/
total cyanide, phenols (4AAP), and total residual chlorine have been
promulgated to accommodate co-treatment of new source ironmaking and
sintering wastewaters.
Justification of_ NSPS
Recycle of sintering wastewaters is practiced at several plants.
Reference is made to Table IX-1 which lists these plants. Filtration
of sintering wastewaters is practiced at plants 0584C, 0860B, 0920B,
and 0946A. Lime or caustic precipitation and alkaline chlorination
are practiced at plant 0860B. Alkaline chlorination is also practiced
at plants 0432A and 0946A. Reference is made to Tables X-1, X-4, and
XII-2 for demonstration of NSPS for sintering operations.
295
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SINTERING SUBCATEGORY
SECTION XIII
PRETREATMENT STANDARDS- FOR DISCHARGES TO
; ' .PUBLICLY OWNED TREATMENT WORKS
Introduction ,
This section presents pretreatment alternatives for sintering
operations with discharges to publicly owned treatment works (POTWs).
One sintering plant currently discharges process wastewaters to a
POTW. The general pretreatment and categorical pretreatment standards
applicable, to sintering operations are discussed below.
General Pretreatment Standards
For detailed information on Pretreatment Standards refer to 46 FR 9404
et seq., "General Pretreatment Regulations for Existing and New
Sources of Pollution," (January 28, 1981). See also 47 FR 1518
(February 1, 1982). In particular, 40 CFR Part 403 describes national
standards (prohibited and categorical standards), .revision of
categorical standards through removal allowances, and POTW
pretreatment programs.
In establishing pretreatment standards for sintering operations, the
Agency considered the objectives and requirements of the General
Pretreatment Regulations. The Agency determined that uncontrolled
discharges of wastewaters from sintering operations to POTWs would
result in pass-through of toxic .pollutants. '
Identification of Pretreatment Alternatives
PSES and PSNS alternative treatment systems are .identical to the BPT
model treatment and the BAT alternative treatment systems (refer to
Sections IX and X for a discussion of these treatment systems). These
alternatives are set out below and illustrated in Figure XIII-1.
PSES/PSNS Alternative 1 - Flocculant addition, gravity sedimentation
in a thickener, vacuum filtration of sludges, and recycle (92%) of the
system effluent. This alternative is the same as the model BPT
treatment system.
PSES/PSNS Alternative 2 - Filtration of the blowdown from the first
alternative. This system is the same as BAT Alternative 1.
PSES/PSNS Alternative 3 - Lime addition and clarification, are
included to treat the blowdown from the first alternative.
PSES/PSNS Alternative 4 - Two-stage (alkaline) chlorination is
included after lime addition and clarification.
299
-------
PSES/PSNS Alternative 5 - Filtration and adsorption on activated
carbon are added to PSES and PSNS Alternative No. 4 for removal of
toxic organic pollutants which may;be present.
PSES/PSNS Alternative 6 - Th'e recycle system (PSES and PSNS No. 1) |
blowdown is processed by vapor compression distillation to achieve
zero discharge.
Selection of. a Pretreatment Alternative
> ;
The pretreatment alternatives described above are designed to control
toxic metals, and thus are designed to minimize pass through of these
pollutants at POTWs which receive sintering wastewaters. The six
pretreatment alternatives accomplish between 93 percent and 100
percent removal of the toxic metal pollutants limited at PSES/PSNS.
PSES/PSNS Alternative 2 was selected as the basis for the promulgated
PSES and PSNS. This alternative is the same as the selected BAT
alternative for sintering operations. PSES/PSNS Alternative 2
provides for substantial removal of toxic metals without the high
costs associated with evaporate technologies. More advanced treatment
is not appropriate, as most of the toxic metals found in sintering
wastewaters are in a particulate form. The removal rates of toxic
metals from untreated sintering wastewaters for PSES/PSNS Alternative
2 are compared to the POTW removal fates for these metals: *
a
PSES/PSNS
Alternative 2 r POTW
Lead
Zinc
98.9%
98.5%
48%
65%
As shown above, the selected PSES/PSNS alternative will prevent pass
through of toxic metals at POTWs to a significantly greater degree
than would occur if sintering wastbwaters were discharged untreated to
POTWs. The achievability of these standards is reviewed in Sections
IX and X. The model treatment system is depicted in Figure XIII-1,
and the PSES and PSNS are presented in Table XIII-1. Reference is
made to Sections IX and X for demonstration of PSES and PSNS.
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IRONMAKING SUBCATEGORY
SECTION I
PREFACE
The USEPA has promulgated effluent limitations and standards for the
steel industry pursuant to Sections 301, 304, 306, 307 and 501 of the
Clean Water Act. The regulation contains effluent limitations for
best practicable control technology currently available (BPT); best
available technology economically achievable (BAT); pretreatment
standards for neti and existing sources (PSNS and PSES); and new source
performance standards (NSPS). Effluent limitations for best
conventional pollutant control technology (BCT) have been reserved for
future consideration.
This part of the Development Document highlights the technical aspects
of EPA's study of the Ironmaking Subcategory of the Iron and Steel
Industry. Volume I of the Development Document addresses general
isssues pertaining to the industry while other volumes contain specific
subcategory reports.
303
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IRONMAKING SUBCATEGORY
SECTION II
CONCLUSIONS
Based upon this ^current study, a review of previous studies, and
comments received on the proposed regulation (46 FR 1858), the Agency
has reached the following conclusions:
1. In the proposed regulation, the ironmaking subcategory was
subdivided into iron blast furnaces and ferromanganese blast
furnaces. That subdivision has been maintained in this
regulation. However, since there were no ferromanganese blast
furnaces in operation during the data gathering period for this
regulation (there are none presently in operation), the Agency
has promulgated only the previous BPT limitations for
ferromanganese blast furnaces and reserved all other limitations
and standards (BAT, BCT, NSPS, PSES,*PSNS). The Agency believes
that BAT ,and BCT limitations and NSPS, PSES and PSNS for
ferromanganese furnaces should be established on a case-by-case
basis using the model wastewater treatment technology outlined
for ironmaking blast furnaces. The Agency found no basis for
further subdividing ironmaking into pig iron producers and
ironmaking furnaces associated with steel production.
2. On the basis of the data collected for this study, the BPT
effluent limitations originally promulgated in 1974 for iron and
ferromanganese blast furnaces based upon recycle of process
wastewaters, are practicable and achievable. The Agency has
promulgated BPT limitations which are identical to those
previously-: promulgated.
3. The Agency's monitoring of ironmaking blast furnace process
wastewaters revealed significant discharges of nine toxic
inorganic and eight toxic organic' pollutants in addition to the
currently limited pollutants. The Agency has concluded that the
discharge of these pollutants can be controlled by the available,
economically achievable technologies which include additional
recycle and blowdown treatment consisting of lime precipitation
and two-stage alkaline chlorination at the BAT level of
treatment. A summary of raw waste loadings, and the discharges
resulting from attainment of the BPT, BAT and PSES limitations
and standards' for ironmaking blast furnaces, is presented below:
305 .
-------
Pollutant Discharges (Tons/year)
Flow (MGD)
Ammonia (as N)
Cyanide, Total
Fluoride
Phenols (4AAP)
TSS
Toxic Metals
Toxic Organics1
Direct Discharges
Raw Waste
825.6
25,147.2
15,088.3
18,860.4
3,772.1
2,388,979.8
33,382.8
201 .2
BPT
29.2
2,672.8
178.2
2,004.6
' 102,
1,87).
77. 1
7. 1
5
0
BAT
16.4
149.7
0.7
498.9
0.4
548.-8
11.4
4.0
Indirect
Discharges
Raw Waste
38.4
1 ,169.6
701 ,
877,
175.
111,115:
1,552.7
9.4
8
2
4
3
PSES
0.8
7.7
0.04
25.6
0.02
28. 1
0.6
0.2
4.
1 Does not include total cyanide or any of the
individual phenolic compounds.
The Agency's estimates of the costs of compliance with -the BPT
and BAT limitations and PSES for the ironmaking subcategory are
presented below for facilities in place as of July 1, 1981. The
Agency has determined the effluent reduction benefits associated
with compliance with the effluent limitations and standards
justify these costs.
Costs (Millions of Julv
Total
434.
30.
13.
7
8
9
Investment
In-
4
Place
12.3
7.6
13.2
Costs
1, 1978 Dol.
Annual
Lars)
Costs
Required In— Place Required
22.
23.
0.
4
2
7
52.
2.
2.
5
3
3
2.
6.
0.
7
R
2
BPT
BAT
PSES
The Agency has also determined that the effluent reduction benefits
associated with compliance with new source standards (NSPS, PSNS)
justify those costs.
The estimated costs of compliance for BAT are based upon the
Agency s assumption that the BAT model two-stage alkaline
chlorination treatment system will be installed at each plant
However, the Agency expects that alternate less costly
technologies will be installed at many plants. These
technologies include minimization of blast furnace blowdowhs with
slag quenching; co-treatment of blast furnace wastewaters with"
cokemaking wastewaters in biological treatment systems, and
certain innovative technologies that can achieve the BAT
limitations at less or equal costs. The Agency estimates that 60
percent of the plants are currently able to evaporate process
wastewaters on slag. The Agency has also determined that the
effluent reduction benefits associated with compliance with new
source standards (NSPS, PSNS) justify these costs.
306
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5.
6.
7.
8.
9.
10,
1 1
The BPT and BAT model treatment systems for the ironmaking
subcategory include wastewater recycle. Responses from the
industry for several plants indicate that they do not experience
scaling, fouling, or plugging problems with the recycle
components used at those plants. The Agency has concluded that a
70 gal/ton blowdown is achievable and practicable as a component
of the BAT model wastewater treatment system. A major steel
company has recommended that the Agency base BAT limitations on a
model flow of 35 gal/ton. -
The Agency has not promulgated BCT limitations since the BCT cost
methodology was remanded to the Agency for reconsideration.
The Agency has promulgated NSPS for ironmaking operations which
are equivalent to the BAT limi-tations for toxic pollutants and
provide for additional suspended solids control'by filtration.
EPA has promulgated pretreatment standards for new (PSNS) and
existing (PSES) sources which limit the quantities of toxic and
nonconventipnal pollutants which can be introduced to POTWs. The
PSES and PSNS are the same as the BAT limitations.
Although several toxic organic and toxic metal pollutants were
found*in untreated ironmaking wastewaters, the Agency believes it
is not * necessary to establish limitations for each toxic
pollutant. The Agency believes that adequate control of toxic
organic pollutants can be achieved by the control of total
cyanide "and phenols (4AAP). Likewise, control of lead and zinc '
will result in comparable control of other toxic metal
pollutants.
To facilitate less costly central treatment and to make the
ironmaking limitations compatible with those for sintering
operations, the Agency has established an oil and grease effluent
limitation for the ironmaking subcategory.
With regard to
concludes that: .
Third Circuit "remand issues," the Agency
Its estimated costs for the model wastewater treatment
systems are sufficient to cover all costs required to
install and operate the model technologies, whether as an
initial fit or a retrofit. The Agency has also concluded
that the ability to implement the model wastewater treatment
systems is not affected by plant.age. A comparison between
the costs reported by the industry and the Agency's
estimated costs for several plants demonstrates that the-
estimated model wastewater treatment costs are sufficient to
account for all site-specific and other incidental costs
which might be incurred.
The use of recycle through cooling towers at the BPT and BAT
levels of treatment and the use of evaporation of process
307
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12,
wastewaters on slag as' a means of achieving the BAT
limitations will result in minor increases in water
consumption. It is estimated that implementation of the
technologies included in the BPT model treatment system will
result in a net increase in water consumption of 3.0 MGD.
This increase represents 0.35 percent of the total volume of
water applied in this subcategory. Implementation of the
treatment technologies included in the BAT model treatment
system will result in a net increase of 3.1 MGD. This
increase represents 0.36 percent of the total volume of
water applied in this subcategory. However, recycle also
significantly reduces or eliminates the discharge of
pollutants. Since the total water consumption is small
compared to total industry water usage, the Agency has
concluded that the impact of the limitations on the
consumptive use of water in this subcategory is minimal and
is justified by the effluent reduction benefits resulting
from their use. These technologies are presently in use at
plants in "arid" and "semi-arid" regions.
Table II-l presents the BPT effluent limitations for the
ironmaking subcategory and the treatment model flow and effluent
quality data used to develop, these limitations. Table II-2
presents the BAT effluent limitations, and the NSPS,*PSES, and
PSNS for the ironmaking subcategory as well as the treatment
model flow and effluent quality data used to develop these
limitations and standards.
308
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IRONMAKING SUBCATEGORY
SECTION III
INTRODUCTION
General Discussion
The production of molten iron from coke, iron ores and beneficiated
iron ores, sintered products, and limestone is an integral part of the
basic steelmaking, process. In 1980, blast furnace iron production in
the United States supported about 61% (on a net tonnage basis) of U.S.
raw steel production. The balance is produced directly from steel
scrap in electric steelmaking remelting furnaces.
™;
Process wastewaters are generated in ironmaking operations as a result
of gas cleaning and cooling which permits the reuse of the gas as a
fuel. Both iron and ferromanganese blast furnaces are included in
'this study.
The Agency previously promulgated a regulation governing blast furnace
operations in 1974 and established limitations for the following
pollutants:
Total Suspended Solids
Ammonia-N
Cyanide (Total)
Phenols (4AAP)
Fluoride
Sulfide
pH
Data Collection Activities
Industry responses to the basic questionnaires (DCPs) comprise the
major source of data for blast furnace operations. The Agency
requested information pertaining to production, processes, process
water usage, process wastewater discharge, and wastewater treatment
systems. The DCP responses for iron blast furnaces are summarized and
tabulated in Table III-l. The DCP information for the ferromanganese
blast, furnace is summarized and tabulated in Table III-2.
The Agency sent detailed questionnaires (D-DCPs) to selected plants to
gather cost and furnace operating data and long-term monitoring data.
The responses to these questionnaires provided useful data which
verified cost estimates, established retrofit costs (if any), and
provided additional effluent quality data. The Agency identified 56
plants with blast furnace operations including two merchant pig-iron
producers. One firm claimed confidentiality with regard to all data
submitted and collected by the Agency during surveys. These data do
not appear .in Table III-l. The Agency also identified one
311
-------
ferromanganese blast furnace and 164 iron blast furnaces at the 56
plants with blast furnace operations. Four of the iron blast furnaces
are associated with merchant pig iron producers.. The operation of 4
to 6 furnaces per plant is not uncommon and one plant had 11 active
furnaces. Table II1-3 summarizes the data base for ironmaking
operations.
Description of the Blast Furnace Process
Blast furnaces are large cylindrical structures in which molten iron
is produced by the reduction of iron bearing ores with coke and
limestone. Reduction is promoted by blowing heated air into the lower
part of the furnace. As the raw materials melt and decrease in
volume, the entire mass of the furnace charge descends. Additional
raw materials are added (charged) at the top of the furnace to keep
the raw material mass within the furnace at a constant level.
., j,
Iron oxides react with the hot carbon monoxide from the burning coke,
and the limestone reacts with impurities in the iron bearing material
and the coke to form molten slag. These reactions start at the top of
the furnace and proceed to completio;n as the charge passes to the
bottom of the furnace. The molten slag, which floats on top of the
molten iron, is drawn off (tapped) by way of a tapping hole. The
molten iron is also tapped through a hole below the slag tapping hole.
The production of iron from a blast furnace is
following approximate charge and yield relationships:
based upon the
Raw Materials
1.8 kkg iron ore
0.6 kkg coke
0.45 kkg limestone
3.2 kkg air
Products
0.9 kkg iron
0.5 kkg slag
4.5 kkg process gas
Blast furnace operations within the U.S. primarily produce (>99%)
basic iron. Several plants have occasionally produced ferromanganese
iron, although during this study only one ferromanganese furnace was
found (Figure 111-4). Production oif iron (rated capacity) on a plant
basis ranges from 800 to 22,200 TPD (Table III-4). The total rated
capacity of all active operations is 294,260 TPD (excluding the
confidential plant). Twenty-five percent of the plants account for 50
percent of the rated capacity.
The gases which are produced in the furnace are exhausted through the
top of the furnace. These gases arfe cleaned, cooled, and then burned
to preheat the incoming air to the furnace. Generally, gas cleaning
involves the removal of the larger particulates by a dry dust
collector, followed by a variety of ^wet" or "wet/dry" gas cleaning
systems for fine particulate removal. The three most common gas
cleaning systems are illustrated in Figures III-l, 2, and 3. The
first system (Type I) uses one wet scrubber (primary); the second
(Type II) uses two wet scrubbers (primary and secondary); and the
312
-------
third (Type III) uses one wet scrubber and one dry air pollution
control device. Gases are cooled with direct contact sprays jn large
gas cooling vessels. At many plants, all or a portion of the gas
cooling wastewaters are cascaded to the gas cleaning systems described
above.
Description of_ Wastewater Treatment
Prior to the mid 1970's, the treatment of ironmaking wastewaters
consisted of the removal of suspended solids by sedimentation in
conjunction with the addition of flocculating agents to improve
removal efficiencies. The clarified wastewaters were typically
discharged directly on a once-through basis without further treatment.
Today, however, about ninety percent of the blast furnace wastewater
treatment systems include recycle (after the thickener , and discharge
Inly a relatively small percentage (generally 5 to.10%) of the process
flow Nearly all recycle systems employ cooling towers^to reduce
recycle wastewater temperatures. The thickener underflows are
typically dewatered by vacuum filters with the filtrate returned to
the thickener influent. The ,dewatered solids are either sent to
sintering operations or to off-site disposal. The specific treatment
practice! in use at each plant are detailed in Table III-1 for iron
blSst furnace plants and in Table III-2 for the ferromanganese
furnace.
313
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TABLE III-3 »
IRON MAKING BLAST FURNACE DATA BASE
Percent of Rated Percent of
No. of Total No.
: Plants of Plants
Plants sampled, for 4 7.4
original study
Plants sampled for 7 .13.0
toxic pollutant study
Total plants sampled 11 20.4
Plants responding via 7 13.0
D-DCP
Plants sampled and/or.v 15 27.8
responding via D-DCP
Plants which responded 54 100
to DCP
Capacity Rated
(Tons/Day) Capacity
15,200 4.7
54,080* 16.8
69,280* 21.5
62,050 19.3
116,640* .36.2
321,511* 100.0
(1) Three plants which responded via D-DCP were also sampled during the
toxic pollutant survey.
* : Does not include the tonnage of the confidential plant.
321
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* TABLE III-4
IRON MAKING FURNACE PRODUCTION
PLANTS RANKED FROM HIGHEST TO LOWEST PRODUCTION
(TONS PER DAY - RATED CAPACITY)
Reference Number
0384A
0860B
0112A
0112B
0432A
0584B
0984C
0112
0112D
0860H
0684F
0856B
0856F
0868A
0584F
085 6N
0448A
0856R
08561
0320
0864A
0060B
0948A*
0432C
0432B*
0112C
0584C
0528A
0060
0856T*
0920B
092 ON
0396A
0396C*
0684G
0920A
0684H
0684B
Rated Capacity
TPD
22,200
20,611
19,140
12,550
11,000
10,900
10,700
10,600
10,500
9,912
9,200
8,600
8,206
8,054
8,020
8,000
7,200
6,750
6,400
6,270
5,700
5,600
5,400
5,367
5,275
5,200
5,200
5,000
4,730
4,707
4,400
4,200
3,400
3,180
3,150
3,100
2,870
2,800
322
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TABLE III-4
IRON MAKING FURNACE PRODUCTION
PLANTS RANKED FROM HIGHEST TO LOWEST PRODUCTION
(TONS PER DAY - RATED CAPACITY)
PAGE 2
Reference Number
0724A
0060A
0684A
0946A*
06841
00*60F
0584D
0248A*
0256E*
08560*
0492A
0426
085 6Q
0948B*
0732A
TOTAL
Rated Capacity
TPD
2,800
2,560
2,520
2,400
2,300
2,200
2,150
2,000
2,000
1,234
1,200
1,100
1,100
1,055
800
321,511 (294,260*)
* : Plant is now shutdown. The capacities of these plants
are not included in the indicated total.
NOTE: The capacity of the confidential plant is not presented
or included in the total.
323
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324
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325
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326
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327
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IRONMAKING SUBCATEGORY
SECTION IV
SUBCATEGORIZATION
Introduction
The steel industry is comprised of separate and distinct processes.
Industry subcategorization was primarily affected by the individual
processes, products, and wastewater characteristics. Other factors
considered for subdivision were: raw materials, wastewater
treatability, size, age, geographic location, and process water usage.
With regard to ironmaking operations, differences between iron and
ferromanganese blast furnaces were identified and found to justify
subdividing the ironmaking subcategory. However, the Agency found no
significant differences between blast furnaces producing pig iron and
those associated with steel production. A discussion of each of these
factors and the subdivision of the ironmaking subcategory follows.
Factors Considered in Subdivision
Manufacturing Process and Equipment
The production of iron and ferromanganese is unique within the steel
industry because it is the only process in which iron bearing
material, limestone and coke are converted into molten iron or
ferromanganese. While many refinements have been made to blast
furnaces to improve operating efficiencies, the basic process has
remained unchanged. The refinements include more stringent control of
the quality of raw materials, reaction rates and times within the
furnace, the use of high top pressures, and oxygen and oil injection.
However, these refinements have not had a major influence on the
quality or quantity of the wastewaters generated during the ironmaking
process and,, thus, do not warrant further subdivision of this
subcategory. f
Final Product
Various grades of iron may be produced in a blast furnace (e.g., basic
iron, ferromanganese, alloy iron), however, over the past decade more
than 99% of the iron produced in this country was basic iron. Less
than 1 percent of total blast furnace production was attributed to
ferromanganese production. A review of the DCP data reveals that only
five U.S.'blast furnaces have historically produced iron other than
pig iron and these furnaces produced only ferromanganese. Two of
these five furnaces produced over 95% of the ferromanganese made in
this country. At this writing, there are no ferromanganese furnaces
in operation. The subdivisions already noted recognize the
differences between iron and.ferromanganese blast furnaces.
329
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Raw Materials
The major raw materials used for ironmaking are coke, iron ore,
limestone, pellets, and sinter. Secondary raw mate-rials include
scrap, gravel, tars and oils of various types, mill scale, flux and
.dolomite. Following is a summary of the major raw materials used in
the iron furnaces:
Feed
Material
Coke
Iron Ore
Pellets
Sinter
Mean
of Burden
26.1
14.0
. 38.8
23.7
Mean Ib/ton
of Hot -Metal
1 ,259
744
1,811
1 ,096
For the one ferromanganese furnace, the raw material composition
consisted of coke (36%), ferromanganese ore (47%), stone (12%) and
other materials (5%). The use of large quantities of ferromanganese
ore in the production of ferromanganese iron was a factor which
distinguishes this process from the basic iron process. Other raw
material differences are minor and;, as such, do not warrant further
subdivision of the ironmaking subcategory.
Wastewater Characteristics
Ironmaking process wastewaters result from cleaning (i.e., scrubbing)
and cooling the dirty furnace exhaust gases. These gases are cleaned
to a high degree and cooled so that they may be reused as fuel to
preheat the air charged to the furnace and, in a number of instances,
for steam production.
The gas streams contain dust, quantities of raw materials and process
reaction products including many pf the same pollutants found in
cokemaking wastewaters. The phenolic pollutants found in ironmaking
wastewaters are attributable to the coke used in the ironmaking
process. Cyanide and ammonia (reaction products formed within the
furnace or transferred from the coke charge to the furnace gases) are
carried over with the gas stream and transferred to the scrubber
waters. Several types of wet gas cleaning systems are used in the
ironmaking subcategory (e.g., venturi scrubbers, adjustable orifice
scrubbers, separators, 'spray chambers). The subdivisions already
noted recognize the differences between iron and ferromanganese blast
furnace wastewaters. Subdivision pn the basis of the type of gas
cleaning system is not -warranted.
Wastewater Treatability
The basic ' treatment in place in. ironmaking wastewaters includes the
removal of suspended solids by gravity sedimentation and the recycle,
to the scrubbers, of 90 to 95% of. the wastewaters after cooling in
evaporative cooling towers. Other pollutants (e.g., metals)
associated with the suspended solids are also removed by the settling
330
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process. The quality and'treatment of blast furnace wastewaters is
similar throughout the subcategory and, as a result, subdivision on
the basis of wastewater treatability is not warranted. The same type
of treatment was provided for the previously noted ferromanganese
furnace.
Size and Age
The Agency considered the impact of the size and age of ironmaking
operations on the subdivision of the ironmaking subcategory. The
Agency determined that age is of little importance because blast
furnaces require periodic major rebuilding, typically every five to
ten years. These major rebuilds often include substantial
modifications to the furnace which, in many cases, is comparable to
the construction of a new furnace. . Most existing blast furnaces have
been rebuilt many times, and some furnaces originally built in the
early 1900's are still operating today. As ;the furnaces are rebuilt,
various technological and production advancements are implemented to
improve furnace operation and gas cleaning.
Figure IV-1 is a plot of effluent flow vs. plant age for plants with
treatment and .recycle facilities. This diagram demonstrates that
there is no correlation between effluent flow and plant age, notably
at flows less than 125 gal/ton (the BPT model flow). Effluent flow
provides a measure of treatment capability, as recycle is one of the
major treatment components used in developing the BPT, BAT, NSPS, PSES
and PSNS alternative treatment systems and the respective effluent
limitations and standards.
Although the age of a blast furnace is difficult to define, the Agency
investigated the effect of age on the feasibility and cost of
retrofitting pollution control equipment. The comparison of the age
of a blast furnace with the year in which pollution control facilities
were installed (see Table IV-1), demonstrates that pollution control
equipment ?has been retrofitted at the oldest furnaces. As noted
above, similar rates of pollutant discharge are achievable at blast
furnaces of all ages. As a result, the Agency has concluded that
retrofitting pollution control facilities to both old and new blast
furnaces is feasible.
The cost of retrofitting the BPT systems to blast furnaces were
provided by industry in DCP responses. The data show that retrofit
costs amount to about 5 percent of the total capital cost of the
pollution control equipment. In addition, as shown in Section VIII of
this report, comparison of actual costs incurred by industry with the
Agency's estimated costs for the same pollution control facilities,
demonstrates that the Agency's estimates are sufficient to account for
retrofit and other site-specific costs. The Agency thus concludes
that the cost of retrofitting pollution control equipment at blast
furnaces is not significant. Since more than 90% of the blast
furnaces have been retrofitted with BPT water pollution control
systems, the feasibility of retrofitting the BPT wastewater treatment
system is well demonstrated. Compliance with-BAT, on the other hand,
331
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will require the installation of add-on treatment systems which, in
most instances, will not involve any significant retrofit costs.
The Agency evaluated the question of size by plotting effluent flow
vs. production (Figure IV-2). This diagram demonstrates that there is
no relationship between effluent flow and plant size as indicated by
treatment and recycle facilities. It also demonstrates that the lower
flows (representative of BPT and BAT model systems) are achieved at
blast furnace operations with high production as well as low
production. The Agency found that many plant sites have several blast
furnaces. These furnaces range from old to new, and from small to
large capacity. . ... . ,
Based upon the above, the Agency finds that both old and newer
production facilities generate similar raw wastewater pollutant
loadings; that pollution control facilities can be and have been
retrofitted to both old and newer production facilities without
substantial retrofit costs; that these pollution control facilities
can and are achieving the same effluent quality; and, that further
subcategorization or further segmentation within this subcategory on
the basis of age or size is not appropriate.
Geographic Location
Location has no effect upon subdivision. Most blast furnaces are
located in the predominant steel producing areas (e.g., Chicago,
Pittsburgh, Cleveland). A few plants are located in water scarce
areas and, as a result, these plants use operational methods (e.g.,
wastewater recirculation) which conserve water. As .of July 1, 1978
about 54 percent of the plants (distributed throughout the country)
had been retrofitted with recycle systems. Currently, recycle systems
are installed at about 90 percent of the blast furnaces in the
country. Of the 4 plants located in "arid" and "semi-arid" areas, 3
plants have installed and one operating recycle systems. The fourth
plant is currently installing a recycle system. ' Also,, wastewater
quality among the plants surveyed is similar and, of the surveyed
plants, one is located in an arid or semi-arid region, one in the
southwest, and the others in the midwest and east.
Process Water Usage
The Agency examined process water usage as a possible basis for
further subdivision. The data indicated that process wastewater flow
had no significant impact on the ability to treat process wastewaters.
In fact, many of the plants with the highest applied flows have lower
discharge flows than plants with lower applied flows. Based upon
these factors, the Agency concluded that further subdivision of the
ironmaking subcategory based upon process water usage is not
warranted.
332
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TABLE IV-1
EXAMPLES OF RETROFIT
IRONMAKING SUBCATEGORY
Blast Furnace
0060B
0112
0112A
0320
0384A
0396A
0396C
0426
043 2A
0432B
0528A
0584C
0584D
0684F
0684G
0684H
0724A
08561
0860B
0860H
0920B
Plant Age
1942
1943
1941
1920-1947
1907
1907-
1903-
1958
1910-
1900-
1954
1956-
1904-
1908
1906
1943
1902
1901
1908
1928
1913
-1909
-1905
-1919
-1966
-1961
-1911
Treatment
Age
1958
1962
1948
1976
1976
1929
1929
1979
1951
1930
1977
1965
1953
1970, 1977
1971
1971
1974
1956,1970
1980
1968,1972
1976
333
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FIGUREIZ-I
BLAST FURNACE-RECYCLING PLANTS
o
ID.
<0
o>
10
CO
I
Sr <*
^ CM
CD
-J cuj
U_ 00
LU
e>
< $
f *D •
o 2
CO
ea
(O
BPT Level
1880 1892 1905 1917 1930 1942 1955 1967 1980
AGE (FIRST YEAR OF PRODUCTION OF OLDEST FURNACE AT PLANT)
334
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FIGURE rZ-2
BLAST FURNACE-RECYCLING PLANTS
g
(O
10
o>
10
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<
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IRONMAKING SUBCATEGORY
SECTION V
WATER USE AND WASTEWATER CHARACTERIZATION
Introduction . . •
This section presents data which characterize wastewater streams
originating in blast furnace operations. These data were obtained
during the field sampling programs conducted at one ferromanganese and
eleven iron blast furnace operations. During the original sampling
program the Agency measured the levels of the pollutants limited under
the originally promulgated effluent guidelines. During the second
field sampling program the levels of those pollutants were again
measured, while additional monitoring was performed for toxic
pollutants. To confirm and expand upon the-toxic pollutant survey
data, the Agency conducted sampling visits at three additional blast
furnace sites (plants 0112, 0684F, and 0860H). The Agency included
data from these visits in the existing data base. The.Agency did not
observe any significant differences in the basic character of the
process wastewaters during these visits.
Description of_ the- Ironmaking Operation and Wastewater Sources
The water " use rates discussed . below pertain only to process
wastewaters, and do not include noncontact cooling or nonprocess
waters. Process wastewater is defined as water which has come into
direct contact: with the process, products, exit gases, and raw
materials associated with blast furnace operations. The wastewaters,
thereby, become contaminated with the pollutants characteristic of the
process. Noncontact cooling water, is defined as that water used for
cooling which does not come into direct contact with the processes,
products, by-products, or raw materials. Nonprocess water is defined
as that water which is used in nonprocess operations, such as for
utility and maintenance requirements.
Water is used within the blast furnace operation for two purposes: (1)
to cool the furnace, stoves, and ancillary facilities, and (2) to
clean and cool the furnace top gases. Although blast furnace
wastewaters are primarily the result of the gas cleaning and cooling
processes, there are other wastewaters sources. During the plant
visits, the Agency found additional wastewaters from a dekishing
operation (plant 0432A), which treated these wastewaters with
sintering wastewaters, and from a slag quench wastewater treatment
operation (plant 0112D). Other miscellaneous waters, such as floor
drains and drip legs,, are also included as part of the process
wastewaters, but, as mentioned above, the gas scrubber and cooler
wastewater is the primary and most important wastewater.
337
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The industry provided process wastewater and treated effluent flow
data in the DCP responses. In many instances these data were reported
as measured values, but some were reported as best engineering
judgment or design values. In most instances DCP flow data are
presented in the summary table; however, where available, plant visit
or D-DCP information was used in lieu of the DCP data. Plant process
wastewater flows varied over a wide range (1034 to 6708 gal/ton) and,
likewise, plant effluent flows also spanned a wide range (0 to 3902
gal/ton). This wide range in flows can be attributed to several
factors, but scrubber design and efficiency, the number of scrubbers
used, and gas cooling requirements generally are the principal factors
influencing water usage. The effluent flow rates are primarily
determined by the amount of recycle employed. There is no indication
that the industry adjusts process water usage to meet reduced or
increased production demands, except to the extent that such
production changes affect the number of furnaces in operation at a
given plant.
One method of conserving water and reducing the quantities of
pollutants discharged is recycle. Recirculation of ironmaking
wastewaters is currently practiced at about 90% of the plants and is a
major component in the BPT model treatment system. Although
recirculation may result in an increase in the concentration of
certain dissolved inorganic pollutants in the recycled wastewater, the
significant reduction in discharge flow which results from recycle
reduces the total pollutant load discharged.
Blast furnace wastewaters contain suspended particulate matter,
cyanide, phenols and ammonia; all of which are limited by current
NPDES permits. Other wastewater pollutants include toxic metals and
certain toxic organic pollutants which originate in the raw materials
or are formed during the reduction process. The concentration data
presented in Tables- V-l through V-4 provide a measure of the
significant pollutants contributed during each pass through the
process. After reviewing the data, the Agency determined that the
effect of makeup water quality on these wastewaters is negligible.
Accordingly, the effluent limitations and standards are based solely
on gross values. Refer to Section VII for a further discussion
regarding this issue.
338
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TABLE V-l
SUMMARY OF ANALYTICAL DATA FROM SAMPLED PLANTS
ORIGINAL GUIDELINES SURVEY
IRON MAKING BLAST FURNACES
Pick-up per pass concentrations (mg/1) in raw process wastewaters
Reference Code 0946A 0396A 0448A
Plant Code L M N
Sample Point(s) l-(6+8) l-(2+4) l-(2+5)
Flow, gal/ton 5,400 .2,057 3,350
pH (Units 6.6 7.1-8.3 6.6
Ammortia (as N) 1.19 2.70 7.98
Fluoride 0.15 1.3 2.24
Phenols (4AAP) 0.120 - 0.529
Suspended Solids 72 611 306
121 Cyanide (Total) 1.4.2 0.806 1.68
0060F
0
l-(4+5)
3,123
7.4-7.5
10.1
0.085
1,167
Average
6.6-8.3
5.49
0.92
0.184
539
0.976
-: Calculation results in a negative value. Negative values were
considered zero in the determination of the averages.
339
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TABLE V-2
SUMMARY OF ANALYTICAL DATA FROM SAMPLED PLANTS
TOXIC POLLUTANT SURVEY
IRON MAKING BLAST FURNACES
Pick-up per pass concentrations (mg/1) in raw process wastewaters
Reference Code 0196A
Plant Code 021
Sample Point (s) (B-D)
Flow, j?al/ton 1280
pH 8.4-8.9
Ammonia (N) 20.4
Fluoride 2.6
Phenols (4AAP)
Suspended Solids 3502
9 Hexachlorobenzene 0.155
23 Chloroform
31 2,4-Dichlorophenol ND
34 2,4-Dimethylphenol ND
39 Fluoranthene 15.955
55 Naphthalene 0.014
65 Phenol 2.135
73 Benzo(alpyrene 14.198
7 6 Chr y s ene 0.420
80 Fluorene
84 Pyrene 15.104
114 Antimony NA
115 Arsenic NA
118 Cadmium 0.036
119 Chromium 0.040
120 Copper 0.099
121 Cyanide (Total) 15.8
122 Lead 53.5
124 Nickel 0.100
125 Selenium NA
128 Zinc 59.9
0112D
026
(G+K)-(I+M+N
1567
i.
6.4-7.1
16.3
-
0.052
386
ND
-
ND
0.0
0.0
0.012
ND
-
0.015
0.021
0.003
NA
NA
0.010
0.046
-
0.008
0.096
0.013
NA
4.55
- : Calculation results in a negative value.
zero in the determination of
NA: No analysis performed
ND: Not detected
the averages
0432A
027
) (C-A)
3091
9.2-9.7
17
6.5
2.91
1610
ND
0.018
ND
0.053
0.082
ND
0.595
0.0
0.0
0.006
0.053
0.033
0.044
0.067
0..067
0.112
12.0
4.67
0.0
0.061
19.9
Negative
•
0684H
028
B-(A+C)
2277
6.9-12.1
10.4
1.8
0.68
1599
ND
-
0.200
0.0
-
—
-
ND
ND
ND
—
NA
NA
0.146
0.628
1.14
0.080
23.2
1.15
NA
29.7
values were
Average
6.4-12.1
16.0
2.7
0.910
1774
0.039
0.004
0.050
0.013
4.009
0.006
0.682
3.550 -
0.109
0.007
3.790
0.033
0.044
0.065
0.195
0.338
6.97
20.4
0.316
0.061
28.5
considered
Overall/.. *
Average
6.V-12.1
10.8
1.8
0.547
1157
0.039
0.004
0.050
0.013
4.009
0.006
0.682
3.550
0.109
0.007
3.790
0.033
0.044
0.065
0.195
0.338
3.97
20.4
0.316
0.061
28.5
(1) Average of all values on Tables V-l and V-2.
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TABLE V-3
SUMMARY OF ANALYTICAL DATA FROM SAMPLED PLANTS
ORIGINAL GUIDELINES SURVEY
FERROMANGANESE BLAST FURNACE
Pick-up per pass concentrations (mg/1) in raw process wastewaters
Reference Code
Plant Code
Sample Point(s)
Flow, gal/ton
pH (Units)
Ammonia (as N)
Manganese
Phenols (4AAP)
Suspended Solids
121 Cyanide (Total)
Gas Scrubber
0112C
Q
2-(4+1)
2.233
12.1-12.2
2,946
17,193
Gas Cooler
0112C
Q
5-4
5,705
8.6—8.7
136
5.41
0.461
50
105
Calculation results in a negative value.
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TABLE V-4
SUMMARY OF ANALYTICAL :DATA FROM SAMPLED PLANTS
TOXIC POLLUTANT SURVEY
FERROMANGANESE BLAST FURNACE
Pick-up per pass concentrations (mg/1) in raw process wastewaters
Reference Code
Plant Code
Sample Points
Flow, gal/ ton
Ammonia (as N)
Manganese
Phenols (4AAP)
Suspended Solids
4 Benzene
23 Chloroform
55 Naphthalene
85 Tetrachloroethylene
86 Toluene
115 Arsenic
117 Beryllium
119 Chromium
121 Cyanide (Total)
122 Lead
127 Thallium
128 Zinc
0112C
025
(B+D) - (C+E)
11.540
25
79
0.142
3750
8.8-11.3
0.013
0.018
0.015
0.055
0.010
1.74
0.003
0.047
0.737
0.045
4.41
-: Calculation results in a negatiye value.
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IRONMAKING SUBCATEGORY
SECTION VI
WASTEWATER POLLUTANTS
Introduction •
This section presents the pollutants which the Agency determined to be
characteristic of ironmaking process wastewaters, the rationale for
their selection and the sources of these pollutants. First, a list of
pollutants considered to be characteristic of ironmaking operations
was developed based upon data gathered during the original guidelines
survey and from the DCP responses. The Agency confirmed that the
initial, list of pollutants was appropriate and added other pollutants
by reviewing monitoring data gathered during the toxic pollutant
survey.
Conventional Pollutants
The originally promulgated BPT effluent limitations included
limitations for total suspended solids and pH. The Agency selected
total suspended solids because of the substantial quantities of
particulates found in the ironmaking process wastewaters.
The Agency limited pH because it is a measure of the acidity or
alkalinity of wastewater discharges. In addition to its direct
adverse environmental impacts, extremes in pH can aggravate the
adverse effects of other pollutants such as ammonia-N and cyanide,
influence corrpsion rates and affect process and wastewater treatment
system operations. The pH of ironmaking process wastewaters is
typically in the neutral to slightly alkaline range.
Nonconventional, Nontoxic Pollutants
In both iron and ferromanganese blast furnace operations, ammonia is
present in the furnace exit gases and in furnace process wastewaters.
Ammonia is present as a result of the various nitrogen compounds which
are driven out of the coke charge during blast furnace operations.
Fluoride is present in ironmaking process wastewaters as a result of
the fluoride compounds, primarily calcium fluoride, present in the
limestone charged to the furnace. The presence of manganese in
ferromanganese blast furnace wastewaters is related to the type of ore
used in ferromanganese furnace operations. Limitations for ammonia-N
were included in the previous regulation.
Toxic Pollutants
Cyanide is generated in the reducing atmosphere of the furnace as a
.result of the reaction of nitrogen in the blast air with carbon from
the coke charge. Larger quantities of cyanide are generated at the
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higher temperatures associated with ferromanganese furnaces. Phenolic
compounds are driven out of the coke charge during blast furnace
operation, Toxic phenolic pollutants were limited indirectly in the
originally promulgated regulation by the limitations established for
phenols (4AAP).
The Agency also considered othet toxic pollutants found in blast
furnace wastewaters. The Agency determined the pollutants existing in
these process wastewaters on the basis of responses to the DCPs, and
analyses performed during the screening phase of the project. Table
VI-1 presents these pollutants.
The Agency evaluated relevant data regarding these pollutants and
calculated net concentration values (reflecting the pollutant pickup
through the process as described in Section V) for each pollutant
detected in the raw process wastewaters. Those pollutants found at an
average net concentration of less than 0.010 mg/1 were excluded from
further consideration. A list of pollutants, including the
conventional and nonconventional pollutants, detected in the raw
process wastewaters at net concentrations of 0.010 mg/1 or greater are
presented in Table VI-2.
The toxic metal pollutants detected in the process wastewaters
originate in the raw materials (primarily the ores and sinter) charged
to the furnaces. These pollutants are present in the blast furnace
exit gases and contaminate the process wastewaters during scrubbing
and cooling operations. The predominant toxic metal pollutants in
ironmaking process wastewaters are lead and zinc. For details
pertaining to the selection of pollutants considered for limitation,
refer to Sections X through XIII.
Although several toxic organic pollutants are included in the list of
pollutants presented in Table VI-1, Table VI-2 does not include all of
these pollutants. The Agency excluded certain toxic organic
pollutants from Table VI-2 (i.e., phthalates) because it believes that
those pollutants are artifacts (i.e., resulting from sampling and
laboratory procedures), which are unrelated to blast furnace
operations. The presence of the remaining toxic organic pollutants is
attributable to the raw materials charged (primarily, the coke
charge). These pollutants can be controlled by limiting other
pollutants.
Other pollutants (e.g., calcium, chloride) are present at substantial
levels in the process wastewaters, but are not included in the list of
selected pollutants since they are nontoxic in nature and difficult to
remove. Treatment of these pollutants in wastewater discharges is not
commonly practiced in any .industry.
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TABLE VI-1
TOXIC POLLUTANTS KNOWN TO BE PRESENT
Iron Blast Furnaces
Phenols(4AAP)
4 Benzene
9 Hexachlorobenzene
23 Chloroform
31 2,4-dichlbrophenol
34 2,4-dimethylphenol
39 Fluoranthene
65 Phenol
73 Benzb(a)pyrene
76 Chrysene
84 Pyrene
85 Tetrachloroethylene
86 Toluene
114 Antimony
115 Arsenic
118 Cadmium
119 Chromium
120 Copper
121 Cyanide (Total)
122-Lead
124 Nickel
125 Selenium
128 Zinc
Ferromanganese Blast Furnaces
Phenols(4AAP)
4 Benzene
23 Chloroform
55 Naphthalene
65 Phenol
85 Tetrachloroethylene
86 Toluene
115 Arsenic
117 Beryllium
119 Chromium
121 Cyanide (Total)
122 Lead
127 Thallium
128 Zinc
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TABLE VI-2
SELECTED POLLUTANTS
Iron Blast Furnaces
pH
Ammonia (as N)
Fluoride
Phenols (4AAP)
Suspended Solids
9 Hexachlorobenzene
31 2,4-Dichlorophenol
34 2,4-Dimethylphenol
39 Fluoranthene
65 Phenol
73 Benzo(a)pyrene
76 Chrysene
84 Pyrene
114 Antimony
115 Arsenic
118 Cadmium
119 Chromium
120 Copper
121 Cyanide (Total)
122 Lead
124_Nickel
125 "Selenium
128 Zinc
Ferromanganese Blast Furnaces
PH .
Ammonia (as N)
Manganese
Phenols (4AAP)
Suspended Solids
4 Benzene
23 Chloroform
55 Naphthalene
85 Tetrachloroethylene
86 Toluene "
115 Arsenic
117 Beryllium
119 Chromium
121 Cyanide (Total)
122 Lead,
127 Thallium
128 Zinc
346
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IRONMAKING SUBCATEGORY
SECTION VII '
CONTROL AND TREATMENT TECHNOLOGY
Introduction
A review of the control and treatment technologies currently in use or
available for use for ironmaking operations provided the basis for the
selection and development of the BPT, BAT, NSPS, PSES and PSNS
alternative treatment systems. DCP, D-DCP, and plant visit data were
reviewed to identify those treatment components and systems currently
in use. Treatment capabilities, either demonstrated in this or in
other subcategories (refer to Volume I), were used by the Agency in
evaluating the various model wastewater treatment technologies.
However, only well demonstrated technologies were used to develop
effluent limitations and standards for ironmaking operations.
This section also presents the raw wastewater and treated effluent
monitoring data from sampled plants, pilot plant studies, and the
monitoring data provided by the industry through D-DCP responses and
responses to supplemental questionaires issued in response to public
comments on the proposed regulation. Thj.s section also presents
descriptions of treatment systems at each of the sampled plants and
examines, in detail, the effect of make-up water quality on raw waste
loadings. •
Control and Treatment Technologies ,
As noted earlier, ironmaking wastewaters result primarily from furnace
top gas cleaning and cooling. Other wastewater sources may be
included; however, these.sources comprise only a minor portion of the
total pollutant load. Although the typical ironmaking wastewater
treatment systems were initially designed for the removal of
particulate matter only, other pollutants, (i.e., ammonia, cyanide and
phenols) are pr.esent in these wastewaters and require treatment.
Following is a summary of actual treatment practices as determined by
the Agency through plant visits and DCP responses (refer to Tables
III-l and III-2).
a. The initial step in the treatment of ironmaking wastewaters is
the removal of suspended solids. All of the plants use a
thickener (or similar gravity sedimentation component) to remove
suspended solids from process wastewaters. The technology also
partially removes other pollutants which are entrained in the
suspended solids (e.g., the toxic metals).
b. The slurry from the bottom of the thickener is dewatered by
various devices. Vacuum filters are used at most plants f,or this
purpose.
347
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g
h,
In order to improve solids removal performance in the thickeners,
coagulant aids such as polymers and ferric chloride are added to
the wastewater stream at the thickener inlet. These coagulant
aids enhance solids removal by aiding in the formation of larger,
more readily settleable particles. This technology also results
in a certain degree of toxic pollutant removal as pollutants
entrained in the solids are removed. Coagulant aids are used at
over three-fourths of the plants.
At five plants, the thickener/clarifier overflow is reused
elsewhere. One method of reuse involves the mixing of the
thickener effluent with incoming fresh water for use in various
process or cooling applications throughout the plant, as well as
for*makeup to the blast furnace gas cleaning and cc-cling systems.
In these operations, the reused water is discharged at various
points throughout the plant. Reuse of the effluent in the plant
water system results in the dilution of the wastewater and does
not result in the removal of the pollutants contained in the
wastewater.
In order to conserve water and to reduce effluent waste loads,
most plants employ systems in which a large portion of the
process wastewater is,recycled. Recycle is now practiced or will
shortly be practiced at about 90% of the plants. In the basic
recycle system, the thickener effluent is recirculated through a
cooling tower to the gas cleaning and cooling operations. The
wastewater discharge in these instances consists of a blowdown
from the thickener effluent or from the cooling tower eftluent.
As noted above, the sludge which settles in the thickener is
dewatered by a vacuum filter and the filtrate is returned to the
thickener influent. In treatment and recycle operations,
flocculation, sedimentation and recycle provide the most
significant means of pollutant load reduction, although some
oxidation and air stripping may occur in the cooling tower.
Chlorination is used at several plants to reduce cyanide and
phenol levels. At one plant, the thickener influent is
chlorinated and discharged without recycle. At another plant,
the thickener effluent is recycled after passage through a
cyanide destruction system (alkaline chlorination). Both bf
these plants were sampled during this study, and the latter plant
exhibited the capability to significantly reduce the levels of
ammonia, cyanide, and phenol. : Alkaline chlorination systems have
been installed at several plants to treat recycle system
blowdowns.
The blowdowns from two recycle systems are discharged to PQTWs.
The blowdowns from recirculation systems at five plants are used
to quench slag or coke, or are evaporated in EOF hoods. This
treatment arrangement,, under careful control, can eliminate the
discharge of pollutants into receiving waters.
48
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Control and Treatment Technologies for BAT, NSPS, PSES and PSNS
Several toxic pollutants were found in the treated effluents of the
sampled plants at concentrations greater than 0.5 mg/1. Because of
high discharge levels and pass through of pollutants-at POTWs, the
Agency has promulgated BAT limitations and NSPS, PSES, and PSNS for
these toxic pollutants. The effluent limitations and standards are
based upon the application levels of treatment beyond that 'for BPT. A
description of the treatment technologies considered by the Agency for
BAT, NSPS, PSES and PSNS is set out below.
Filtration
Filtration is a common and effective method of removing suspended
solids and those pollutants (particularly the toxic metals) which are
entrained in these solids. Filtration can be used as the last major
component in a treatment system or may be used to provide pretreatment
prior to another component (such as an activated carbon system).
Generally, the filter bed is comprised of one or more filter media
(e.g., sand, anthracite, garnet) and a variety of filtration systems
are available (flat bed, deep bed, pressure or gravity). As noted
above, filtration can be used to reduce the discharge of certain
insoluble toxic pollutants, (the non-dissolved toxic metals). However,
other toxic pollutants, such as ammonia-n, cyanide and phenols, will
not be removed from the process wastewaters by this technology.
Filtration is used in a wide variety of steel industry applications,
including three central treatment facilities (one was sampled) which
treat- ironmaking wastewaters.
Toxic Metals Removal Using Sulfide Precipitation
Sulfide precipitation has been shown to be capable of reducing
effluent toxic metals concentrations substantially below the levels
achieved in lime flocculation and precipitation systems. Some of the
toxic metals which can effectively be precipitated with sulfide are
zinc, copper, nickel and lead. The increased removal efficiencies can
be attributed to:the comparative solubilities of metal sulfides and
metal hydroxides. In general, the metal sulfides are less soluble
than the respective metal hydroxides. However, an excess of sulfide
in a treated effluent can result in objectionable odor problems. A
decrease in wastewater pH will aggravate this problem, and if
wastewater treatment pH control problems result in even a slightly
acidic pH, operating personnel can be affected. One method of
controlling the presence of excess sulfide in the treated effluent
involves feeding an iron sulfide slurry. Ferrous sulfide will not
readily dissociate in the waste stream, ensuring that the free sulfide
level is kept below objectionable levels. However, the affinities of
the other metals in the waste stream for sulfide are greater than that
of iron, which causes other metal sulfide precipitates to form
preferentially to iron sulfide. Once the sulfide requirements of the
other metal precipitates are satisfied, sulfide remains as a ferrous
precipitate and the excess iron from the sulfide is precipitated as a
hydroxide. With the use of filtration following sulfide addition,
349
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significant toxic metals load reductions can be achieved. Sulfide
precipitation is not used for the treatment of BPT effluents in the
ironmaking subcategory.
Alkaline Chlorination
Certain nonconventional and toxic pollutants are amenable to treatment
by oxidation reactions. Because it is well demonstrated on a full
scale basis within the ironmaking subcategory, the Agency considered
two-stage alkaline chlorination as an alternative treatment technology
at the BAT, NSPS, PSES and PSNS levels of treatment. Alkaline
chlorination involves the addition of chlorine (a strong oxidizing
agent) to process wastewaters which already are, or which have been
adjusted, to an alkaline pH. Chlorine addition is typically
accomplished by the eduction of the gas into a pumped wastewater
sidestream which is returned to the treatment process, or by the
addition of a liquid such as sodium hypochlorite to the wastewaters..
The oxidation reduction potential (ORP) of the wastewaters being
treated is measured during treatment to monitor and control the
alkaline chlorination treatment process.
Two-stage alkaline chlorination is used primarily to destroy, ammonia,
cyanide, phenols, and other toxic organic pollutants. The
end-products of the cyanide destruction reactions are CO2 and N2. The
end-products of the oxidation of ammonia are principally N2 and H2O,
while the end-product of phenols oxidation is CO2.
While alkaline chlorination is an effective means of removing ammonia,
cyanide, and phenols, it can produce toxic organic compounds at
undesirable levels. These compounds, primarily halomethanes, are
by-products of the reaction between chlorine and certain constituents
(precursors) in the ironmaking wastewaters. Studies conducted by both
the Agency and industry on blast furnace wastewaters treated by
alkaline chlorination show varying levels of halomethane formation.
The data indicate that formation of halomethanes is largely dependent
upon the treatment configuration and the presence of precursors
(measured as suspended solids). Where adequate suspended solids
removal is achieved prior to chlorination, the total halomethane
concentration found in the chlorinated effluent is held to levels of
about 0.1 mg/1 (the drinking water standard for trihalomethanes).
Studies performed at potable water treatment plants resulted in
similar findings.
Monitoring conducted at Plant 0432A, where alkaline chlorination was
practiced on blast furnace wastewaters after suspended solids removal,
showed that only low levels (0.05 mg/1) of chloroform were formed.
No other halomethanes were detected. Data from a pilot plant study
conducted by U.S. Steel at Plant 0860B, indicate less than 0.1 mg/1 of
total halomethanes in the chlorinated effluent (Table VI1-8). The
pilot facility included pH adjustment and clarification prior to
chlorination. Data for full scale operation of the treatment facility
are similar to the pilot scale data. Pilot studies were also
conducted by Metcalf & Eddy, Inc, for EPA using single-stage and
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two-stage alkaline chlorination systems, with and without air
stripping. These studies again demonstrated that the system with
suspended solids removal preceding chlorination had the lowest level
of halomethane formation (total halomethane of 0.2 mg/1 and
trihalomethane of 0.06 mg/1). This system also included air stripping
of the wastewater prior to the addition of chlorine. Air stripping,
however, is not expected to have a significant effect on the presence
of precursors, since studies conducted at water treatment facilities
indicate that aeration prior to chlorination has no effect on
halomethane formation. Considering the available data, the Agency
believes that alkaline chlorination of ironmaking and sintering
wastewater preceded by removal of suspended solids will result in the
formation of only low levels of halomethanes while substantial
quantities of ammonia, cyanide, and phenols (4AAP) will be removed.
Dechlorination
To minimize the potential toxicity of wastewaters which have been
chlorinated, the Agency considered dechlorination to reduce total
residual chlorine levels in the treated discharge. Dechlorination is
practiced on a full scale basis at plant 0584C for a central treatment
facility which includes sintering and ironmaking wastewaters. This
technology is also widely practiced in the electric power generation
and electroplating industries. Reducing agents, such as sulfites or
sulfur dioxide, are added to the chlorinated effluent in sufficient
quantities to react with the excess residual chlorine, thereby forming
nontoxic chlorides.
Removal of. Organlcs With Activated Carbon
Adsorption with activated carbon is widely used for the removal of
organic pollutants from wastewaters. This technology is used to
reduce the concentrations of oxygen demanding substances in POTW
effluents. This technology is also used to remove organic pollutants
in industrial wastewaters including those from petroleum refining,
organic chemical manufacturing and cokemaking. It should be noted
that several toxac organic pollutants found in ironmaking wastewaters
are also found in cokemaking wastewaters. This can be attributed to
the use of coke in the ironmaking process. Activated carbon is
installed on a full scale basis for the treatment of ironmaking and
sintering wastewaters at Plant 0860B.
Operating guidelines for the use of activated carbon specify that when
combined wastewater streams are being treated or where the wastewater
to be treated has significant turbidity, clarification or filtration
is necessary to Achieve optimum treatment efficiency. The use of
chemical precipitation and diatomaceous earth filtration may be
necessary to achieve the clarity required for the removal of the toxic
organic pollutants which may be present at low levels. Suspended
solids control is also necessary because particulates in water can
adsorb organic pollutants, and then release the organics after passing
through the carbon bed.
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Laboratory tests performed on single compound systems indicate that
processing with activated carbon may achieve residual levels on the
order of 1 microgram per liter for many of the toxic organic
pollutants. The Agency believes that the following compounds (among
others) respond well to adsorption: carbon tetrachloride, chlorinated
benzenes, chlorinated ethanes, chlorinated phenols, haloethers,
phenols, nitrophenols, DDT and metabolites, pesticides, polynuclear
aromatics and PCBs.
The pH of the wastewater to be treated must be controlled within the
range 6-8 to minimize dissociation of both acid and basic compounds.
Generally, normal pH variations within the neutral range will not
significantly affect the operation of activated carbon systems.
Vapor Compression Distillation
Vapor compression distillation is a process which can be used to
achieve zero discharge. In this process, the wastewaters are
evaporated resulting in the concentration of non-volatile pollutants
and .other constituents in the wastewater to slurry consistency. The
steam distillate leaving the system is condensed and recycled back to
the production process for resue. The slurry discharge can be dried
in a mechanical drier or allowed to crystallize in a small solar or
steam-heated pond prior to final disposal. One desirable feature of
the process is its relative freedom from scaling. Because of the
unique design of the system, calcium sulfate and silicate crystals
grow in solution as opposed to depositing on heat transfer surfaces.
Economic operation requires a high calcium to sodium ratio (hard
waters).
Plant Visit Data
Table VII-1 provides a legend for the various control and treatment
technology abbreviations used in various tables throughout this
report. Table VI1-2 presents a summary of raw wastewater and effluent
data for the iron blast furnaces visited in conjunction with the
original guidelines survey. Table VII-3 presents a summary of all
iron blast furnace raw wastewater data collected during the toxic
pollutant survey, and Table VI1-4 presents a summary of the respective
effluent data. Table VI1-5 presents a summary of raw wastewater and
effluent data from a ferromanganese blast furnace visited during the
original guidelines survey. Table VII-6 presents : a summary of
ferromanganese raw wastewater and effluent data obtained during the
toxic pollutant survey.
Table VII-7 presents a summary of the effluent data provided in the
D-DCPs. Tables VI1-8 and VI1-9 present summaries of pilot plant data
from plant 0860B. Table VII-10 presents a summary of long-term
effluent data for the recycle system blowdown at plant 0860B. This
recycle system is the same as the BPT treatment,model system. Table
VII-11 presents a summary of effluent data from the full-scale
352
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alkaline chlorination/activated carbon treatment system in use at
plant 0860B. ."•-.-
Plant Visits
Iron Blast Furnaces
Following are summaries of the treatment in place at eight iron blast
furnaces visited during the original guidelines and toxic pollutant
surveys. Plant schematics are found at the end of this section.
Plant L (0946A) - Figure VII-1
Blast furnace gas cleaning system wastewaters are combined with sinter
plant wastewaters and treated by sedimentation in a • thickener,
followed by alkaline chlorination, filtration and recycle with the
blowdown being discharged to a receiving stream.
Plant M (0396A) z Figure VII-2
Blast furnace gas cleaning system wastewaters are treated by
sedimentation in a thickener, evaporative coolinland recycle. A
portion of the thickener overflow is discharged to a POTW while most
of the overflow is passed through a cooling tower and recycled.
Plant N (0448A) - Figure VII-3
Blast furnace gas cleaning wastewaters are treated by sedimentation in
a thickener, evaporative cooling and recycle. The blowdown is
completely evaporated by slag and in coke quenching, and EOF hood
sprays. There is no wastewater discharge to receiving waters.
Plant 0 (0060F) - Figure VII-4
Blast furnace gas cleaning .system wastewaters are treated by
sedimentation in a thickener, evaporative cooling, and recycle. An
electrostatic precipitator is used following the venturi scrubbers and
gas cooler. The blowdown is completely evaporated by slag and coke
quenching, and: in EOF hood sprays. There is no wastewater discharge
to a receiving stream.
Plant 021 (Confidential)
Wastewaters from individual blast furnace' scrubbing systems are
combined and treated by sedimentation in a thickener, acid addition
for pH adjustment, evaporative cooling and recycle. A portion of the
recycle water is blown down. , The blowdown is 'combined with other
plant wastewaters and treated further at a central treatment facility.
Plant 026 (01 1;2D) - Figure VII-5
Blast furnace? gas cleaning system wastewaters are combined with slag
pit quench wastewaters and treated by pH adjustment with acid,
353
-------
coagulation with polymer, sedimentation in a thickener, evaporative
cooling and recycle. A portion of the recycle water is blown down to
a central treatment facility which receives wastewaters from several
steelmaking and forming and finishing operations.
Plant 027 (0432A) - Figure VIJ-6
Blast furnace gas cleaning, sintering, and dekishing wastewaters are
combined in a central treatment facility which includes sedimentation
in a thickener, and alkaline chlorination. The effluent from the
once-through treatment system is discharged to a receiving stream.
Plant 028 (0684H) z Figure VII-7
Blast furnace gas cleaning system wastewaters are treated by aeration,
pH adjustment with lime, chlorination, coagulation with polymer,
sedimentation in a thickener, evaporative cooling and recycle. A
portion of the recycle water is blowndown to a POTW.
Ferromanqanese Blast Furnace -
Ferromanganese blast furnace operations are similar to iron blast
furnace operations as top gases are cleaned using the same types of
wet scrubbers. However, major differences between iron and
ferromanganese furnaces with respect' to raw materials and furnace
operating temperatures result in differences in process wastewater
quality. Ferromanganese furnaces produce higher levels of cyanide and
manganese.
Information on ferromanganese furnaces is limited because,
historically only a few furnaces in the U.S. have produced
ferromanganese. In fact, at the time of this study only one furnace
was operational. Recently this remaining furnace was shut down and is
not expected to renew operations i;n the forseeable future.
During the course of the original guidelines and toxic pollutant
surveys, this particular ferromanganese operation was surveyed twice.
The operation was sampled a second time because its wastewater
treatment system had been upgraded since the first visit. The result
of this upgrading was that the operation ceased discharging po.llutants
to the receiving stream. Approximately 90 gal/ton of wastewater 1/ft
the system-with the filter cake which was transported to a landfill
for disposal.
A brief description of this plant under the two different treatment
approaches is provided below:
Plant Q (01120 - Figure VII-8
Venturi scrubber wastewater treatment included sedimentation in a
thickener and complete recycle to 'the scrubbers. Gas cooler
wastewaters were discharged to a receiving stream without treatment.
354
-------
Plant 025 (0112C) z Figure VI1-9
Venturi scrubber wastewater treatment included sedimentation in a
thickener and complete recycle to the scrubbers. Gas cooler
wastewater treatment included sedimentation in a thickener with the
thickener effluent being completly recycled to the coolers. This
plant had no wastewater discharge to a receiving stream.
Effect of Make-up Water Quality
Where the mass loading of a limited pollutant in the make-up water to
a process is small in relation to the raw waste loading of that
pollutant, the impact of make-up water quality on wastewater treatment
System performance is not significant, and, in many cases, not
measurable. In these instances, the Agency has determined that the
respective effluent limitations and standards should be developed and
applied on a gross basis.
Table VII-12 presents an analysis of the effect of make-up water
quality on the raw waste loadings of each pollutant limited in the
regulation for the ironmaking subcategory. These data were obtained
from blast furnace sampling surveys completed for this study. The
analysis clearly demonstrates that the levels of the limited
pollutants in-;the intake waters are not significant compared to raw
waste loadings. The intake waters added less than one percent to the
raw waste loadings of each limited pollutant. Thus the Agency has
determined that the limitations and standards should be applied on a
gross basis, except to the extent provided by 40 CFR 122.63th).
355
-------
TABLE VII-1
OPERATING MODES, CONTROL AND TREATMENT
TECHNOLOGIES AND DISPOSAL METHODS
Symbols
A. Operating Modes
1. OT
2. Rt,s,n
Once-Through
Recycle, where t
• \ 3
n
type waste
stream recycled
% recycled
U
T
Untreated
Treated
P
F
S
FC
BC
VS
FH
3. REt,n
4. BDn
Process Wastewater
Flume Only
Flume and Sprays
Final Cooler '
Barometric Cond.
Abs. Vent Scrub.
Fume Hood Scrub.
of raw waste flow
of raw waste flow
of raw waste flow
of FC flow
of BC flow
of VS flow
of FH flow
Reuse, where t 3 type
n » % of raw waste flow
t: U m before treatment
T =• after treatment
Slowdown, where n'» discharge as % of
! raw waste flow
B. Control Technology
10. DI Deibnization
11. SR
12. CC
13. DR
C. Disposal Methods
20. H
21. DW
Spray/Fog Rinse
Coutitercurrent Rinse
Drag-out Recovery
Haul Off-Site
j1
Deep Well Injection
356
-------
TABLE VII-1
OPERATING MODES, CONTROL AND TREATMENT
TECHNOLOGIES AND DISPOSAL METHODS
PAGE 2
Disposal Methods (cont.)
22. Qt,d
Coke Quenching, where t = type
d = discharge as %
of makeup
t: DW a Dirty Water
CW = Clean Water
23. EME
24. ES
25. EVC
Evaporation, Multiple Effect
Evaporation on Slag
Evaporation, Vapor Compression Distillation
Treatment Technology
30. SC Segregated Collection
Equalization/Blending
Screening
Oil Collecting Baffle
Surface Skimming (oil, etc.)
Primary Scale Pit
Secondary Scale Pit
Emulsion Breaking
Acidification
Air Oxidation
Gas Flotation
Mixing
Neutralization, where t 3 type
31. E
32. Scr
33. OB
34. SS
35. PSP
36. SSP
37. EB
38. A
39. AO
40. GF
41. M
42. Nt
t: L = Lime
C = Causiic
A = Acid
W = Wastes
0 3 Other, footnote
357
-------
TABLE VII-1
OPERATING MODES, CONTROL AND TREATMENT
TECHNOLOGIES AND DISPOSAL METHODS
PAGE 3
D.
Treatment Technology (cont.)
43. FLt
44. CY
44a. DT
45. CL
46,
47. TP
48. SLn
49. BL
50. VF
51. Ft.m.h
Flocculation, where t = type
L = Lime
A = Alum
P 3 Polymer
M = Magnetic
0 = Other, footnote
Cyclone/Centrifuge/Classifier
Drag Tank
Clarifier
Thickener
Tube/Plate Settler
Settling Lagoon, where n ™ days of retention
time
Bottom Liner
Vacuum Filtration (of e.g., CL, T> or TP
underflows)
Filtration, where t = type
m = media
h = head
m
D 3 Deep Bed
F a Flat Bed
0
Sand
Other,
footnote
3 = Gravity
P = Pressure
52. CLt
53. CO
Chlorinatioh, where t = type
t: A - Alkaline
B = Breakpoint
Chemical Oxidation (other than CLA or CLB)
358
-------
TABLE VII-1
OPERATING MODES, CONTROL AND TREATMENT
TECHNOLOGIES AND DISPOSAL METHODS
PAGE 4 '
D.
Treatment Technology (cont.)
54. BOt
55. CR
56. DP
57. ASt
58. APt
59. DSt
60. CT
61. AR
62. AU
63. ACt
64. IX
65. RO
66. D
Biological Oxidation, where t 3 type
t: An = Activated Sludge
n » No. of Stages
T =» Trickling Filter
B ™. Biodisc
0 = Other, footnote
Chemical Reduction (e.g., chromium)
Dephenolizer
Ammonia Stripping, where t s type
t: F '
L '
C '•
Ammonia Product, where t a type
t
Free
Lime
Caustic
S =» Sulfate
N = Nitric Acid
A = Anhydrous
P » Phosphate
H = Hydroxide
0 = Other, footnote
Desulfurization, where t =
t:
Cooling Tower
Acid Regeneration
Acid Recovery and Reuse
Activated Carbon, where t
type
Q
N
Qualifying
Nonqualifying
type
ts P
G
Powdered
Granular
Ion Exchange
Reverse Osmosis
Distillation
359
-------
TABLE VII-1
OPERATING MODES, CONTROL AND TREATMENT
TECHNOLOGIES AND DISPOSAL METHODS
PAGE 5
D.
Treatment Technology (cont.)
67. AA1
68. OZ
69. DV
70. CNTt,n
71. On
72. SB
73. AE
74. PS
Activated Alumina
Ozonation
Ultraviolet Radiation
Central Treatment, where t = type
process flow as
% of total flow
1 ™ Same Subcats.
2 '=• Similar Subcats.
3 * Synergistic Subcats.
si
Subcats.
4 » Cooling Water
Incompatible
Other, where n ™ Footnote number
Settling Basin
Aeration
Precipitation with Sulfide
360
-------
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363
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TABLE VII-5
SUMMARY OF ANALYTICAL DATA FROM SAMPLED PLANTS
ORIGINAL GUIDELINES SURVEY
FERROMANGANESE BLAST FURNACE
Raw Wastewaters
Plant Codes
Sample PointCsK
Flow, gal/tonU;
Scrubber
0112C
Q
2
2,233
Gas Cooler
0112C.
Q
5
5,705
mg/1
lbs/1000 Ibs
pH, Units
Ammonia (as N) .
Manganese
Phenols (4AAP).
Suspended Solids
121 Cyanide (T)
Effluent
Sample Point(s)
Flow, gal/ton
C&TT
12.2-12.2
156
2,960
19.1
17,260
3,886
1.45
27.6
0.178
161
36.2
T, VF, RTP-100
No discharge of
wastewater
pollutants
mg/1
lbs/1000 Ibs
8.6-8.7
136 3.24
6.05 0.144
0.471 0.0112
57 1.36
104 2.47
No treatment
provided
364
-------
TABLE VII-6
SUMMARY OF ANALYTICAL DATA FROM SAMPLED PLANTS
TOXIC POLLUTANT SURVEY
FERROMANGANESE BLAST FURNACE
Reference Code
Plant Code
Sample Point (s)
Flow, gal/ton
C&TT
Raw Wastewaters
0112C
025
B+D
11,540
Effluent
0112C
025
0
CL, T, CT, RTF
Ammonia (as N)
Manganese
Phenols (4AAP)
Suspended Solids
pH
4 Benzene
23 Chloroform
55 Naphthalene
85 Tetrachloroethylene
86 Toluene
115 Arsenic
117 Beryllium
119 Chromium
121 Cyanide (Total)
122 Lead
127 Thallium
128 Zinc
0.017
0.158
0.038
0.064
0.013
7.67
0.011
0.176
692
1.89
0.328
30.5
8.8-11.3
lbs/1000 Ibs
34.2
12.2
0.312
200
0.000818
0.00760
0.00183
0.00308
0.000626
0.369
0.000529
0.00847
33.3
0.0910
0.0158
1.47
365
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374
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375
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376
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377
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378
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379
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380
-------
331
-------
-------
IRONMAKING SUBCATEGORY
SECTION VIII
COST, ENERGY AND NON-WATER QUALITY ASPECTS
Introduction
This section presents the incremental costs which the Agency estimates
the industry will incur in meeting the limitations and standards.
These costs were determined on the basis of the appropriate model
wastewater treatment systems. The analysis includes a consideration
of energy requirements; non-water quality impacts; and, the
techniques, magnitude and costs associated with the application of the
BPT, BAT, BCT, NSPS, PSES and PSNS model wastewater treatment
technologies. . This section also reviews the consumptive use of water
as it relates to the ironmaking subcategory.
Comparison of_ Industry Costs and EPA Model Costs
Tables VIII-1 and VIII-2 present the water pollution control costs
reported by dischargers which were sampled during the original or
toxic pollutant surveys or which responded to the D-DCPs. The
reported costs have been updated to July 1978 dollars. In most
instances, standard cost of capital and depreciation factors were
applied to the . reported costs to determine those portions of the
annual costs of operation. In the remaining instances, these costs
were provided by the industry. The amortization costs reported by the
industry (cost of capital and depreciation) are similar to the
amortization costs which would have been determined by applying the
factors noted on the tables.
As shown below, the capital cost data provided by the industry are
compared with the Agency's estimates of required expenditures for
eleven plants. The Agency's estimates are based upon the model
treatment system factored to the size of each of the eleven plants.
-------
Plant No.
Actual Costs
Estimated Costs
0060
*0060F
*01 12
*0112D
0320
0384A
*0396A
0432A
0684F
*0868A
*0920B
0946A
TOTAL
2,963,000
6,020,000
7,384,000
8,217,000
14,806,000
20,896,000
1,664,000
9,290,000
22,507,000
4,707,000
5,172,000
6,492,000
110,118,000
5,158,700
5,226,300
13,425,400
14,327,300
10,808,100
22,284,500
6,786,400
9,572,600
16,238,400
7,637,800
7,921,800
4,004,700
123,392,000
*Plants with effluent flows equal to or less than
model effluent flow of 125 gal/ton.
the BPT treatment
NOTE: The data reported for Plant 0684F include costs for
screening, settling tanks, and other items not included in
the Agency's estimated costs. There are .two blast furnace
wastewater treatment facilities at this plant.
Estimated costs for two-thirds of the plants listed above are greater
than the actual costs reported for these plants. More important,
however, is the comparison of the actual and estimated costs totals,
as this comparison reflects upon the overall accuracy of the Agency's
estimate of the costs of compliance for the entire ironmaking
subcategory. Since actual costs are 89 percent of the estimated
costs, the Agency concluded that its estimates fairly reflect the
actual cost of compliance with the limitations and standards, and that
these estimates are sufficient-to account for site-specific and other
incidental costs (such as retrofit). A more detailed discussion of
this issue is presented in Section VII of Volume I. It should also be
noted that the reported cost total for those plants with effluent
flows equal to or less than the BPT treatment model effluent flow is
only 60 percent of the estimated cost total for these plants. This
demonstrates that the -limitations and standards may be achieved at
less cost than estimated by the Agency.
In addition, the Agency compared its estimated costs for its model
treatment system with a cost estimate prepared by an engineering firm
for the same model treatment system. This firm estimated the costs
for the second BAT treatment alternative in the October 1979 draft
development document and supplied its estimate as a comment regarding
the draft development document. A comparison of the flow basis and
estimated costs for the treatment model and company model follows:
304
-------
Flow
Capital
EPA Estimate
50 gal/ton
$2.49 million
Engineering Firm
Estimate
100 gal/ton
$3.94 million
Reviewing the cost figures alone, the Agency's estimate would appear
to be significantly less than the engineering firm's estimate. Upon
further analysis, however, it is clear that the difference between the
estimated costs is attributable to the different flow basis used to
size the treatment components. The Agency's .estimated cost is $3.78
million, when the Agency's flow basis is adjusted to conform to the
engineering firm's model (100 gal/ton). This is within 4.1 percent of
this .engineering firm's unsolicited estimate thereby providing a
further check :on the Agency's costing methodology. The 'general
discussion regarding this issue in Volume I provides further
verification of the accuracy of the Agency's estimates of treatment
model costs.
»
Control and Treatment Technology in Use
or Available to Blast Furnace Operations
The technologies in use or available for use to treat blast furnace
wastewaters are presented ,in Table VIII-3. It should be noted that a
discharger is not required to use any of the model technology
components, as any method of treatment which achieves the effluent
limitations or standards is adequate. In addition to listing the
treatment methods available, these tables provide the following for
each component:
1. Description
2. Implementation time
3. Land requirements
Later in this section, the Agency sets out the estimated costs for the
individual components of these treatment systems.
With the exception of the vapor compression distillation component,
all of the ^treatment technologies listed on Table VIII-3 are
demonstrated within the ironmaking subcategory. As noted in Section
VII, these technologies have been proven to be reliable and effective
for treatment of ironmaking wastewaters. Vapor compression
distillation is a technology which 'has been demonstrated, in other
industries. Refer to Section VII for additional details regarding
this technology.
Estimated Cost for the Installation of. Pollution Control Technologies
A. Costs Required to Achieve the BPT Limitations
The first step in determining the estimated costs of compliance
involved the development of a treatment model upon which the cost
estimates could be based. The. model size (tons/day) was
385
-------
developed on the basis of the average production capacity for all
blast furnace sites. This method was used so that the concept of
joint treatment of wastewaters from several blast furnaces at one
site could be more accurately represented. The Agency developed
the applied flow for the model treatment system on the same
basis.
The components and effluent flows discussed in Sections IX and X
were then included to complete the development of the treatment
model. Subsequently, unit costs for each treatment model
component were developed. , Table VII1-4 presents the estimated
investment and annual expenditures associated with the
application of BPT model treatment technologies to the model
plant. The.capital and annual costs needed to achieve the BPT
level of treatment were determined for each blast furnace site by
adjusting the model treatment component costs for plant capacity
using the 0.6 power factor. These estimates pertain to only iron
blast furnaces as no ferromanganese blast furnaces are currently
in operation. As noted previously, ferromanganese blast furnace
production has been only a minor segment of. all ironmaking
operations. In order to assess the economic impact of the BPT
effluent limitations upon the industry, the Agency estimated the
expenditures required to bring each blast furnace site from
current (July 1, 1981 ) 'treatment levels to the BPT level. The
initial status of each plant was determined from DCP responses
which described the treatment facilities in-place as of January
1978. The Agency has updated the status to July 1, 1981, taking
into account the blast furnaces that have since been retrofitted
with BPT treatment systems, and the permanent retirement of some
older, uncontrolled furnaces. The estimated capital requirement
of BPT for this subcategory is $22.4 million, while the estimated
annual cost is $2.7 million. The capital and annual costs of
treatment facilities in-place, as of July 1, 1981, at existing
iron blast furnaces amount to $412.3 million and $52.5 million,
respectively.
B. Costs Required to Achieve the BAT Limitations
The Agency considered six BAT alternative treatment systems for
the ironmaking subcategory. Each of the systems is depicted in
Figure VIII-1. The descriptions, rationale, and additional
details for these alternatives are provided in Section X. The
Agency's estimates of the investment and annual costs for the BAT
treatment alternatives are presented in Table VII1-5. The
treatment costs for each site were determined by adjusting the
model treatment costs for size. Total estimated capital and
annual costs for the subcategory represent the sum of the
treatment costs for each active iron blast furnace site. The
estimated investment and annual costs for each alternative
treatment system for the ironmaking subcategory are as follows:
33,6
-------
BAT
Alternative
1
2
3
4
5
6
Investment
In-place
Costs ( * ) ( $ )
Required
Annual Costs ($)
578,600
1,318,600
3,530,800
7,630,500
10,756,900
0
6,997,800
9,963,900
11,268,300
23,204,500
112,334,400
171,635,900
In-place
89,400
154,400
550,400
2,266,400
2,662,100
0
Required
934,400
1,333,300
1,714,400
6,771,700
18,365,000
35,055,000
(i) Four plants which already discharge to quenching operations
are not considered in alternatives two through six, as the Agency
expects that wastewaters from these plants will continue to be
disposed of in this manner.
As noted in Section X, the BAT effluent limitations are based
upon BAT Alternative 4. The Agency recognizes, however, that
wastewaters from some plants will be disposed of by evaporation
'on slag (Treatment Alternative 1). Although less expensive than
BAT-4 BAT T can be used to achieve the BAT limitations at many
plants. The Agency did not promulgate BAT limitations based upon
BAT Alternative 1 because not all blast furnaces are equipped
with adjacent slag processing operations. For the purpose of.
determining industry cost requirements, the Agency assumed that
BAT-4 would be installed at" all blast furnace sites, with the
exception of the four plants currently achieving, zero discharge
through slag quenching. This is a conservative assumption since
a survey conducted by the Agency indicates that 60« of the plants
may be able to achieve compliance through BAT-1. The actual
costs incurred by the industry may, therefore, be substantially
less than estimated by the Agency. The Agency is also aware of
certain technologies that may be' innovative for treating
ironmaking wastewaters to achieve the BAT limitations at less
cost. These technologies may also see widespread use in the
industry. •
C. BCT Cost Comparison
The BCT analysis was not performed since the governing BCT
regulation was remanded by the Fourth Circuit Court (See Volume
I); BCT effluent limitations have been reserved for the
ironmaking subcategory.
D. Costs Required to Achieve NSPS
Seven alternative treatment systems, depicted in 'Figurer VIIIT1,
were developed for new blast furnaces. The NSPS alternative
treatment systems include the treatment components of the model
BPT and BAT alternative treatment sytems. The NSPS model
treatment costs are presented in Table VII1-5.
387
-------
E. Costs Required to Achieve the Pretreatment Standards
Pretreatment standards apply to those plants which discharge to
POTW systems. The seven pretreatment alternatives are the same
as the NSPS model treatment systems. These systems, shown in
Figure VIII-1, provide for reductions in toxic pollutant
discharge levels and in effluent flows. Refer to Section XIII
for additional information pertaining to pretreatment standards.
The model costs for the pretreatment alternatives are included in
Table VIII-5. The capital annual costs for the two existing
indirect dischargers were determined by adjusting the model
treatment costs for size. The total costs for each PSES model
'treatment system are as follows:
PSES
Alternative
1
2
3
4
5
6
7
Investment Costs ($)
Annual Costs ($)
In-place
12,916,700
0
0
60,400
297,500
297,500
0
Required
0
232,800
386,400
386,300
648,700
3,84.9,400
5,966,200
In-place
2,133,900
0
0
10,200
120,900
120,900
Required
'0
32,700
51,700
53,800
176,400
591,000
1,218,500
The costs for alternatives 2 through 7 are incremental over the
costs for alternative 1 .
Energy Impacts Due to the
Installation of the Alternative Technologies
Comparatively modest amounts of energy are required by the various
levels of treatment for the ironmaking subcategory. The major energy
expenditures are being incurred at the BPT level while the BAT
alternative treatment systems require relatively minor additional
energy expenditures. This relationship reflects the use of vacuum
filters, cooling towers, and primary recycle technologies (the major
energy consumers) in BPT. Energy requirements at the NSPS, PSES and
PSNS levels of . treatment will be similar to the total of the
corresponding BPT and BAT treatment systems.
A. Energy Impacts at BPT
The Agency estimates that the BPT treatment components for all
ironmaking operations consume about 420.0 million kilowatt hours
of electricity per year. This figure represents 0.74% of the 57
billion kilowatt hours of electricity used by the steel industry,
in 1978.
-------
B. Energy Impacts at BAT
The estimated subcategory BAT energy requirements, and the
respective percent of industry power use in 1978, are as follows:
BAT
Alternative
1
2
3
4
5
6
Million
kwh/yr
4.30
3.74
5.15
13.26
29.08
545.22
of Industry
Usage
0.008
0.007
0.009
0.023
0.052
0.96
The Agency considers the energy requirements set out above to be
reasonable and justified, especially when compared to the total
industry energy use and the pollutant reduction benefits
described below.
Energy Impacts at NSPS, PSES and PSNS.
The Agency estimates of the energy requirements for the NSPS
Pretreatment models are. as "follows:
and
PSES
Alternative
1
2
3
4
5
6
7
Million
kwh/yr
19,
0.
0,
0,
0.
1,
54
20
19
18
59
44
27.96
% of Industry
Usage
0.034
0.00035
0.00033
0.00032
0.0010
0.0025
0.049
Model
NSPS/PSNS -1
NSPS/PSNS -2
NSPS/PSNS -3
NSPS -4
PSNS -4
NSPS -5
PSNS -5
NSPS -6
PSNS -6
NSPS/PSNS -7-
Million
kwh/yr
9.77
9.87
9.86
9.90
9.86
10.11
10.06
10.53
10.49
23.75
389
-------
The energy requirements for PSES-2 through 7 are incremental over
the requirements for PSES-1.
Non-water Quality Impacts
There are minimal non-water quality impacts associated with the model
technologies. Three impacts were analyzed: air pollution, solid
waste disposal, and water consumption. The analysis conducted for the
ironmaking subcategory found that no significant non-water quality
impacts will result from the installation of the treatment systems
under consideration.
A. Air Pollution
The use of wet cooling towers in the BPT model treatment system
may result in the atmospheric discharge of volatile compounds and
ammonia-N. Cooling tower drift may contain toxic pollutants at
levels similar to those present in recycled wastewaters.
However-, the Agency believes that any adverse environmental
impact associated with these emissions is minimal and localized.
As no other air pollution impacts are expected as a result of
industry's compliance with the BPT limitations, the Agency
concluded that there are no significant air pollution impacts
associated with the limitations.
With respect to the BAT alternative treatment systems, the
evaporation of process wastewaters on slag (BAT Alternative 1)
may result in the emission of pollutants contained in the
wastewater into the atmosphere, however, this impact will also be
minimal and localized. Activated carbon regeneration (required
in association with BAT 5), may also result in the emission of
some pollutants found in the wastewater. However, under proper
operating conditions these pollutants would be incinerated.
B. Solid Waste Disposal
The model BPT and BAT alternative treatment systems will generate
quantities of solid wastes. A summary of the solid waste
generation rates (on a dry solids basis) at the BPT and BAT
levels of treatment for the ironmaking subcategory is as follows:
Treatment
Level
BPT
BAT-1
BAT-2
BAT-3
BAT-4
BAT-5
BAT-6
Solid Waste Generation for the
Subcategory (Tons/Year)
5.14 million
Minimal
Minimal
7,800
21,450
21,450
Minimal
390
-------
Although the quantities of solids generated at the BPT level are
substantial, these solids are often sintered and thus reused in
the blast furnace. Moreover, the incremental solid wastes
generated at the BAT level are not significant compared to those
generated at BPT.
The Agency estimates that the NSPS and Pretreatment alternative
treatment systems will generate the following amounts of solid
wastes on a model plant basis:
Treatment
Level
NSPS/PSES/PSNS - 1
NSPS/PSES/PSNS - 2
NSPS/PSES/PSNS - 3
NSPS/PSES/PSNS - 4
NSPS/PSES/PSNS - 5
NSPS/PSES/PSNS - 6
NSPS/PSES/PSNS - 7
Solid Waste Generation for the
Treatment Model (Tons/Year)
119,465
119,465
119,465
119,665
120,015
120,015
119,465
As noted previously, the NSPS, PSES, and PSNS alternative
treatment systems are similar to the BPT and BAT treatment
systems. The solid wastes generated at the NSPS, PSES and PSNS
levels of treatment are of the same nature as the solid wastes
generated by the model BPT and BAT alternative treatment systems
and thus present the same disposal requirements and possibilities
for reprocessing.
C. Water Consumption t
In the ironmaking subcategory, the Agency has included wet
cooling towers in the BPT, BAT, NSPS, PSES and PSNS alternative
treatment systems. Wet cooling towers are presently used at
nearly 90% of the blast furnace sites to reduce system heat loads
and thus permit higher recycle rates. The use of those devices
results in some degree of water consumption (in the form ot
evaporation and drift). In response to the Third Circuit Court s
remand of this issue, the Agency carefully analyzed the amount of
water consumed by evaporation and drift. In addition, the Agency
analyzed the amount of water which will be evaporated for those
discharges employing BAT Alternative 1 (evaporation of process
wastewater on slag).
The total water usage in the subcategory is 864 MGD. The Agency
estimates that the net amount (i.e., in addition to current
consumption) of water which would be consumed in the ironmaking
subcategory at the BPT and BAT levels of treatment are as
follows:
391
-------
Treatment
Level
BPT
BAT-1
BAT-2
BAT-3
BAT-4
BAT-5
BAT-6
Net Water
Consumption
3.0 MGD
18.1 MGD
0.1 MGD
0.1 MGD
0.1 MGD
0.1 MGD
0.1 MGD
% of Total
Volume Applied
0.36
2.1
0.01
0.01
0.01
0.01
0.01
The estimates set out above are in addition to the 11.2 MGD of
water presently consumed in existing cooling devices (1.3% of
total applied volume).
Based upon the relevant factors discussed in Section III of
Volume I, as well as those discussed above, the Agency has
concluded that the impact of the limitations and standards for
the ironmaking subcategory on the consumption of water in the
steel industry on . both a nationwide and an arid and semi-arid
regional basis is minimal and justified, especially in light of
the effluent reduction benefits associated with these limitations
and standards. Recycle systems have been installed at three of
the four blast furnace operations in arid or semi-arid regions,
and a recycle system is currently being installed at the
remaining operation. Thus, these effluent limitations will cause
no significant incremental water consumption at plants located in
"arid" and "semi-arid" regions.
Summary of Impacts
1 " l 4
The Agency concludes that the effluent reduction benefits shown below
justify the adverse environmental impacts associated with energy
consumption, air pollution, solid waste, and water consumption
discussed above:
392
-------
Raw Waste and Effluent Loads (Tons/Year)
Direct Discharges
Raw Waste
BPT
BAT-4
Flow (MGD)
Ammonia (N)
Cyanide, Total
Fluoride
Phenols (4AAP)
TSS
Toxic Metals
Toxic Organicsd)
825
25,147
088
15,
18
860
3,772
1,388,979
33,382
201
2,
2;
1,
29.
672.
178.
004.
102.
871 .-
77.
7.
2
8
2
6
5
0
1
1
16.
149.
0.
498.
0.
548.
11 .
4.
4
7
7
9
4
8
4
0
38
1,169
701
877
175
111,115
1,552
9
.4
.6
.8
.2
.4
.3
.7
.4
Indirect Discharges
Raw Waste PSES
0.8
7.7
0.0
25.6
0.0
28.1
0.6
0.2
ci>Does not include cyanide or any of the individual phenolic
compounds.
The Agency also concludes that the effluent reduction benefits
associated with compliance with new source standards (NSPS, PSNS)
outweigh the adverse energy , and : non-water quality environmental
impacts. ;
393
-------
\0
a
§
CM -4
O —I
O
§
a
ES
O 4) W
0) C co
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o o u
O C -H
CJ (0 rH
-i b *H (d
BO J 3
a
i . 1
ft* « «-*
i-l CO
a o
u u
TOTAL
394
-------
'8
.3 o
b e
>-• •*
R ~E S
* CM -H
O CO %O
o- oo oo
« * CTS
»-* 00 -4
ft t^ •&
• ID 0>
: I
^J *«4
Si-
1
I
2 -S
S. I
CO -* *^
r*. s-^ -a-
m oo w
I
K -u
g
a • s •
ll
SB U
C4
S
1 w
%O
S
oo
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S X,
1.
§1
•H e
a
a
a
-------
TABLE VII1-2
EFFLUENT TREATMENT COSTS
FERROMANGANESE BLAST FURNACES
(ALL COSTS ARE EXPRESSED IN JULY, 1978 DOLLARS)
'Plant Code
Reference No.
Initial Investment Cost
Annual Costs
Capital^1'
Operation and Maintenance
Energy, Power, Chemicals, etc.
Other (sludge)
TOTAL
$/Ton
Q
0112C
025
0112C
$3,809,500
$ 342,474
382,780
151,260
283,118
$1,159,632
$ 5.47
$9,296,200
$ 835,728
491,760
68,844
317,004
$1,713,336
$ 7.27
(2)
(1) The capital charge is based upon the formula, 0.0899 x initial investment.
(2) Inasmuch as a portion of the investment cost covers the period 1964-68,
the cost for this period was broken down to 65 percent in 1964 and
35 percent in 1967 based on 308 information.
396
-------
TABLE VIII-3
CONTROL AND TREATMENT TECHNOLOGIES
IRONMAKING SUBGATEGORY
C&TT
Step
B
E
H
Description
THICKENER - This step provides suspended
solids removal as a result of sedimentation.
Significant reductions in the levels and loads
of those pollutants (principally toxic metals)
in the particulate form are also provided.
FLOCCULATION WITH POLYMER - This step enhan-
ces suspended solids and particulate pollu-
tant removal performance in Step A.
VACUUM FILTER - Vacuum filters are used to
dewater and reduce the volume and mass,
of the sludges removed from the sediment-
ation steps. The filtrate is re-turned
to the treatment system influent.
COOLING.TOWER - This C&TT step reduces the
recycled wastewater heat load.
RECYCLE - At BPT ninety-six percent of the
cooling tower effluent is returned to the
process. At BAT levels of treatment, ninety-
eight percent of the cooling tower effluent is
returned to the process.
DISPOSAL ON SLAG - Slowdown from the cool-
ing tower, Step E, is disposed of on slag.
The recycle system blowdown must be restricted
to that volume which can be evaporated on slag.
PRESSURE FILTRATION - Filters provide addi-
tional suspended solids and particulate
pollutant removal.
NEUTRALIZATION WITH LIME - Lime is added for
toxic metals removal and pH control. This
enhanced capability results from the removal,
by sedimentation, of metallic hydroxide
precipitates.
Implementation
Time (months)
15 to 18
Land
Usage
69,000
15 to 18
1000
20,000
18 to 20
12 to 14
2500
3000
6 to 8
15 to 18
12
No addi-
tional re-
quirements .
625
625
397
-------
TABLE VIII-3
CONTROL AND TREATMENT TECHNOLOGIES
IRONMAKING SUBCATEGORY
PAGE 2
Description
K
M
N
INCLINED PLATE SEPARATOR - This component pro-
vides additional suspended solids and particu-
late pollutant removal capability as a
result of enhanced sedimentation performance.
NEUTRALIZATION WITH ACID - Prior to discharge,
acid is added (as needed) to the treated
effluent, in order to assure that the treated
effluent pH is within the neutral range.
TWO-STAGE CHLORINATION - This C&TT step pro-
vides the ability to destroy cyanide and to
oxidize phenols and ammonia. The basic pro-
cesses involved: lime addition; first stage
chlorine addition; first step reaction period;
acid addition; second stage chlorine addition;
and, second stage reaction period.
SULFUR DIOXIDE ADDITION - The reducing agent
sulfur dioxide is added to the Step K
effluent in order to remove essentially all
residual chlorine resulting from Step K.
ACTIVATED CARBON ABSORPTION - Prior to dis-
charge, the treated wastewaters (the filter
effluent) from BAT Alternative No. 5 are
passed through a column of granular activated
carbon in order to remove residual levels of
toxic organic pollutants. This removal is
achieved by adsorption on the activated car-
bon.
EVAPORATION - The effluent from the BPT
treatment system model is delivered to a
vapor decompression evaporation system.
This system produces a distillate quality
effluent and crystalline solids.
RECYCLE - The effluent of Step N is returned
to the process as a makeup water supply.
Implementation
Time (months)
10 to 12
8 to 10
12 to 15
Land
Usage
225
625
2500
8 to 10
15 to 18
— 625
625
18 to 20
1000
12 to 14
625
390
-------
o «n
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v *
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s
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S
1
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IRONMAKING SUBCATEGORY
SECTION IX
EFFLUENT QUALITY ATTAINABLE THROUGH THE APPLICATION OF THE BEST
PRACTICABLE CONTROL TECHNOLOGY CURRENTLY AVAILABLE
The Agency promulgated the same limitations that were originally
promulgated in June 1974 *as the Best Practicable Control Technology
Currently Available (BPT) for ironmaking operations. The June 1974
development document2 provides background information on the
development of the originally promulgated limitations.
Identification of BPT
A. Ironmaking Blast Furnaces
The BPT model treatment system includes sedimentation in a
thickener; coagulant addition for enhanced suspended 'solids
. removal performance; sludge dewatering by vacuum filtration; and,
recycle through a cooling tower of about 96% of the thickener
effluent. The remaining thickener effluent is discharged as
blowdown. Figure IX-1, depicts the treatment system described
above.
B. Ferromanganese Blast Furnaces ,
The iron blast furnace BPT model treatment system also applies to
ferromanganese blast furnace operations. However, different BPT
effluent limitations were promulgated to account for the higher
blowdown concentrations of pollutants limited at BPT for
ferromanganese furnaces.
Table IX-1 summarizes the characteristics of ironmaking and
ferromanganese blast furnace raw process wastewaters. "The 30-day
average BPT effluent limitations are as follows:
iFederal Register; Friday, June 28, 1974; Part II, Environmental
Protection Agency: Iron and Steel Manufacturing Point Source
Category; Effluent Guidelines and Standards; Pages 24114-24133.
2EPA-440/I-74-a, Development Document for Effluent Limitations
Guidelines and New Source Performance Standards for the Steelmaking
Segment of the Iron and Steel Manufacturing Point Source Category.
403
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kg/kkg of Product
(lb/1000 Ib of Product)
Pollutants
Total Suspended Solids
Ammonia (N)
Cyanide (Total)
Phenols (4AAP)
pH (Units)
Ironmaking
Blast Furnaces
0.0260 .
0.0535
0.0078
0.0021
Ferromanganese
Blast Furnace
0.1043
0.4287
0.1563
0.0208
Within the range 6.0-9.0
are three times the
The maximum daily effluent limitations
average values presented above.
Selection of_ BPT Limitations
A. Treatment System
As noted in Section VII, the Agency found that each of the
components included in the BPT model treatment system is
presently in use at most blast furnace sites. Given the
widespread use of these components, the Agency believes that the
BPT model treatment system is appropriate.
B. Model Treatment Flow Rates
The Agency retained the BPT model treatment system effluent flow
rate of 125 gal/ton used-to develop the previously promulgated
BPT limitations. As shown in Table IX-2, this flow is
demonstrated at several plants.
C. Effluent Quality
The Agency also retained the BPT model treatment system effluent
quality from the prior regulation. These concentrations are as
follows:
30-Day
Average
Daily
Maximum
Total Suspended Solids
Ammonia-N
Total Cyanide
Phenols(4AAP)
50
120
15
4
mg/1
150
375
45
12
mg/1
As shown in Section VII, these concentrations are readily
demonstrated at plants with recycle systems in place.
404
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D. Justification of BPT Effluent Limitations •
Table IX-3 presents effluent data for ironmaking operations
sampled by the Agency and data from D-DCP respondents which
support the BPT limitations. The only sampled plants or D-DCP
respondents which did not comply with the BPT limitations are
those which had once-through treatment systems. The Agency could
not fully evaluate the compliance status of a few plants because
of insufficient data supplied by the industry. These plants are
not listed in the table. Although, alkaline chlorination is used
at a few of the plants that comply with the BPT limitations,
nearly all plants achieve the BPT limitations with no treatment
of the recycle system blowdown. The sampled plants not included
in Table IX-3 could comply with the BPT limitations if recycle
systems were installed. Recycle systems have been installed at
many of these plants since these data were collected. The Agency
estimates that about ninety percent of the currently operating
ironmaking operations are in compliance with the BPT limitations.
405
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TABLE
RAW WASTEWATER CHARACTERISTICS
IRONMAKING SUBCATEGORY
(All values expressed in mg/l unless otherwise noted)
IRON MAKING
BLAST FURNACES
FERROMANGANE:SE
BLAST FURNACE
FLOW (gal/ton)
3200
II.54O
AMMONIA (as N)
10
71
CYANIDE(Total)
10
692
PHENOLS (4AAP)
2.5
6.5
SUSPENDED
SOLIDS
900
4160
pH (Units)
6-10
8.8- 11.3
(I) Raw wastewater quality reflects the discharge from a once-through system.
(2) Data are based upon one plant which was operating at the time of
sampling. These values reflect the increases due to recycle.
406
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TABLE IX-2
BPT EFFLUENT FLOW JUSTIFICATION
IRONMAKING SUBCATEGORY
Plant Reference
Code
0112
0112D
0448A
0528A
0684F
0732A
08561
0856N
0860B
0860H-
0868A-02
0920B
0948A-02
0948C
Discharge
Flow (gal/ton)
71
73
101
66
61
<10(3)
60.7
76.5
45.5
120
122
83
96
85
Operating
Mode
RTP-96
RTP-97
RTP-97
RTP-97
RTP (>90)
RTP-(<100)
RTP-(>98)
RTP-(>90)
RTP-(>90)
RTP and RUP-96
RTP and RUP-96
RTP and RUP-96
RTP-90
RTP and RUP-96
Source of
Data
D-DCP
VISIT
VISIT
Request
Request^2'
VISIT
Request
Request;(1)
(1)
Request,
DCP
D-DCP
D-DCP
DCP
DCP
(1) These data represent averages of all long-term data
submitted by these plants.
(2) This value is an average of long-term data submitted by this plant,
These data reflect the effects of discharge flow reduction efforts,
(3) Estimated value.
407
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TABLE IX-3
JUSTIFICATION OF BPT EFFLUENT LIMITATIONS (kg/kkg)
IRONMAKING SUBCATEGORY
Ammonia
(as N) Cyanide (T)
Iron Making Blast Furnaces
BPT 0.0535 0.00780
Plants
L (0946A)
N (0448A)
0.0186 0.000173
NJ
0684H
(1)
0.00724
0 (0060F) / 0.0356 0.00468
026 (0112D) 0.0122 0.000014
028 (0684H) 0.0125 0.000178
030 (0112) 0.0437 0.00666
0.0117 0.000750
Ferromanganese Blast Furnace
BPT 0.429 0.156
Phenols
(4AAP)
NA
0.0208
025 (0112C) No discharge of process wastewater
pollutants.
TSS
0.00210 0.0260
0.000363 NJ
0.000015 0.0163
0.000008 0.0198
0.00157 NJ
0.000066 0.0174
pH
0.000004 0.0199 8.0
C&TT Components
6.0-9.0 T,FLP,VF,CT,
RTP-96
7.6 T,CLA,SS,
Filters,RTP-37
6.7-8.1 T,CT,SL,RTP-97
ES
T,FLP,CT,VF,
RTP-97,ES
7.3-7.5 T,FLP,VF,NA
CT,RTP-95
8.2-8.8 A,CLA,FLP,CL,
CT,FLFC,NA,
RTP-92
7.2-7.5 T,FLP.,NA,VF,
CT,RTP(Unk)
0.0161 8.6
A,NL,FLP,CLA
CL,VFVCT
0.104 6.0-9.0 See comments
in Section IX.
CL,T,VF,
CT,RT1>-100
(1) Based on D-DCP analytical data
NA: No analysis performed
NJ: Not justified
Note: For definitions of C&TT Codes, see Table VII-1.
408
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409
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IRONMAKING SUBCATEGORY
SECTION X
EFFLUENT QUALITY ATTAINABLE THROUGH THE APPLICATION OF
BEST AVAILABLE TECHNOLOGY ECONOMICALLY ACHIEVABLE
Introduction
This section identifies six BAT alternative treatm'ent systems
considered by the Agency in developing the BAT effluent limitations.
Since there are no ferromanganese blast furnaces in operation or
scheduled for operation the Agency has not promulgated BAT effluent
limitations for ferromanganese blast furnaces. Should any
ferromanganese blast furnaces operate, appropriate BAT effluent
limitations should be established on a case by case basis using "best
professional judgment". In those instances, the model BPT and BAT
treatment systems for iron blast furnaces should be considered. The
only ferromanganese blast furnace In operation at the time of the
Agency's monitoring programs was operating with no discharge. The
technologies included in the BAT alternative treatment systems are
capable of attaining similar pollutant effluent levels for both iron
and ferromanganese blast furnace operations. However, for the BAT
model treatment system, operating costs for ferromanganese treatment
systems are likely to be higher due to the higher levels of ammonia-n
and total cyanide in wastewaters from ferromanganese operations.
Identification of BAT
Based upon the information presented in Sections III through VIII, the
Agency developed the following treatment technologies as BAT
alternative treatment systems for the ironmaking subcategory. These
treatment systems are .designed to be compatible with the BPT model
treatment system. Schematic diagrams of the alternatives- are
presented in Figure VIII-1.
BAT Alternative 1 -
The blowdown flow is reduced by increasing the recycle rate of the BPT
model treatment system to the point where it can be consumed in the
quenching (cooling) of blast furnace slag. The treatment system
includes a slag pit collection and recycle sump and associated pumps.
As all of the blowdown is evaporated, process wastewater pollutants
are not discharged into receiving waters. "
BAT Alternative 2_
The blowdown flow is reduced to 70 gal/ton by increasing the recycle
rate of the BPT model treatment system. The reduced blowdown is
treated by filtration. Pressure filters are used to reduce toxic
metals in the blowdown hy removing those toxic metals present in
411
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particulate form. The filters also remove other pollutants which may
be entrained in suspended solids.
BAT Alternative 3^
The reduced blowdown flow (70 gal/ton) is treated with lime
precipitation and sedimentation. Lime is added to remove both
dissolved and particulate toxic metals present in ironmaking
wastewaters. The toxic metal hydroxides are gravity settled in an
inclined plate separator prior to discharge. Toxic metals as.well as
other pollutants' present in particulate form will also be removed by
sedimentation. ;
BAT Alternative 4_ .
The reduced blowdown (70 gal/ton) is treated with two-stage alkaline
chlorination. Lime is added to the blowdown to raise the pH to 10.5
or greater. The toxic metal precipitates and other suspended solids
formed by lime addition are removed in inclined plate separators prior
to alkaline chlorination* Chlorine is added to the first reactor to
convert the cyanides to cyanates and to oxidize ammonia-N and phenolic
compounds. As the wastewaters leave the first reactor, acid is added
to reduce the pH to 8.5. Additional chlorine is added in the second
reactor to complete the oxidation of cyanides, as well as residual
ammonia-N and phenolic compounds. The effluent is then dechlorinated
with appropriate reducing agents prior to discharge.
BAT Alternative 5_
Additional treatment of the effluent from BAT Alternative 4 is
provided by adsorption on activated carbon. Activated carbon will
remove residual levels of toxic organic pollutants which may be
present in the wastewater.
BAT Alternative 6. .
The blowdown from the recycle system (70 gal/ton) is processed by
vapor compression distillation. The high purity water (steam
condensate) is returned to the recycle system resulting in zero
discharge of wastewater.
Except for vapor compression distillation, the treatment technologies
described above are in full scale use at one or more blast furnace
wastewater treatment systems, or demonstrated on the basis of pilot
plant studies in this subcategory. The applicability of each
treatment system is reviewed .below.
The pollutants selected for limitation and the effluent limitations
for each alternative are presented in Table X-l. The Agency's
selection of pollutants for which BAT limitations have been
promulgated is based upon the following considerations: the relative
412
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level, discharge load, and environmental impact of each pollutant; the
need to establish practical monitoring requirements; and, to
facilitate co-treatment of ironmaking and sintering wastewaters, a
common practice in the industry.
Treatment for the selected pollutants will generally result in a
similar or greater degree of treatment for pollutants chemically
related to the selected pollutants and found at lower levels. For
example, nine toxic metals were identified in the process wastewaters
from blast furnace operations at concentrations greater than 0.010
mg/1. However, the Agency has promulgated BAT limitations for only
lead and zinc. Significant removal of the other metals will occur in
conjunction with the treatment and control of these metals.
Rationale for the Selection of BAT
Treatment Technologies
Recirculation of treated wastewater is one of the major components of
the BAT model treatment system. The recirculation rate of the BPT
model treatment system is increased from 96% (125 gal/ton) to 98% (70
gal/ton blowdown). Recycle of blast'furnace wastewaters is widely
demonstrated in the industry. The 70 gal/ton blowdown rate is also
demonstrated and is discussed in detail below. In the first
alternative, the blowdown is reduced to the point where it can be
consumed to quench (cool) slag. Approximately 60% of the blast
furnaces have adjacent slag operations. This practice is demonstrated
in the industry (Plants 0060F, 044-8A, 0860H) and provides a fairly
inexpensive approach to achieve the BAT limitations. Filtration is
used to treat wastewaters from three blast furnace operations (Plants
0584C, 0860B and 0946A. Precipitation and alkaline chlorination are
used in several blast furnace wastewater treatment systems (0320,
0504C, 0860B). The primary purpose of alkaline chlorination is the
oxidation of ammonia-N, cyanide, phenolics, and other toxic organic
pollutants. The fifth BAT alternative includes activated carbon for
the removal of residual levels of toxic organic pollutants from the
effluent of BAT Alternative 4. this is demonstrated on a full-scale
basis at Plant 0860B in this subcategory.
Model Flow Rate
The Agency has retained the BPT applied flow of 13,344 1/kkg (3200
gal/ton) for use in the BAT alternative treatment systems. The
discharge flow of 292 1/kkg (70 gal/ton) used to develop the proposed
BAT limitations has been retained. In the draft development document
the Agency cited data for Plant 0112 that indicate 70 gal/ton is an
achievable blowdown rate for blast furnace recycle systems. The
industry noted that longer term data for. that plant indicate the
blowdown rate for this operation is about 78 gal/ton, and that monthly
average flows during the period of record exceed 130 gal/ton. The
industry contends that flows less than 70 gal/ton cannot be maintained
for long periods of time because of. the build-up of dissolved solids
which can lead to an increased potential for stress corrosion and
-------
mineral scaling. The Agency disagrees that 70 gal/ton is not
sustainable on a long term basis. Data for Plant 0112 show that 70
gal/ton has been maintained for long periods of time without fouling,
scaling, or plugging problems. The Agency notes that the blowdown
rate at this plant is controlled to maintain cyanide discharges below
certain levels and that dissolved solids or other indices relating to
fouling or scaling are not used to control the blowdown rate. Thus,
the Agency believes a blowdown rate of 70 gal/ton is achievable at
this plant. The Agency solicited data for other well-operated blast
furnace recycle systems. .These data are shown below:
Plant
0528A
08561
0860B
Period Covered
by Date
January 1978-
July 1980
November
May 1981
1979-
October 1980-
December 1980
Average Daily
Blowdown (gal/ton)
68.5
60.7
45.5
Based upon these data; the performance data for Plant 0112 noted
above; the performance of one of the two blast furnace recycle systems
at Plant 0684F; and, the performance at Plants 0060F, 0448A, and 0860H
where blast furnace blowdowns are consumed on slag and other sources,
the Agency believes that 70 gal/ton is an achievable blowdown rate for,
all blast furnaces. These plants are typical of those in the
industry, are located in different geographic areas, use different raw
materials, and are operated by different companies. Aside from the
demonstration of the 70 gal/ton blowdown rate noted above, one major
steel company suggested the Agency use a blowdown rate of 35 gal/ton
to establish BAT effluent limitations.
Wastewater Quality
The average and maximum effluent concentrations included in each BAT
treatment alternative are presented in Table X-l. No data are
presented for Alternatives 1 and 6 since these alternatives result in
zero discharge. The effluent levels for Alternatives 2 through 5 are
discussed below.
Ammonia-N
Alternatives 2'and 3 do not provide for treatment of ammonia-N. Thus,
the discharge of ammonia-N from these systems is the same as that from
the BPT recycle system.
To some extent, ammonia-N will concentrate in recycle systems as the
blowdown rate is brought under hydraulic control and ' reduced.
However, the discharge loading will decrease with decreasing blowdown
rate rather than remain the same. Thus, there is an advantage to
414
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minimizing blowdown rate. The investment costs of the treatment
facilities will be reduced as well as the costs of chemicals required
for blowdown treatment.
Alternatives 4 and 5 include alkaline chlorination for treatment of
ammonia-N, total cyanide, phenols (4AAP), and other toxic organic
pollutants. The proposed BAT ammonia-N limitation is based upon a
concentration of 1.0 mg/1 obtained from pilot plant studies. The
industry submitted data for a full scale system (Plant 0860B) that
suggests a BAT limitation based upon 10 mg/1 might be more
appropriate. The Agency sollcated long term data for this plant.
Based on its analysis of these data (Table A-38, Appendix A, Volume
I), the Agency concluded that a model effluent concentration of 10
mg/1 is appropriate for this technology as these data demonstrate that
a well operated system can achieve that value. The data presented in
Table X-l reflect that value. Ammonia-N is not removed by the
activated carbon system installed at this plant. Activated carbon
system are not capable of ammonia-N removal. Available data
demonstrate that the alkaline chlorination process used prior to
activated carbon consistently removes ammonia-N to less than 10 mg/1.
Total Cyanide
Alternatives 2 and 3 do not include treatment for total cyanide.
Thus, the level of discharge was set at the level determined from BPT
recycle system blowdowns, or about 5 mg/1. This value is supported by
the data presented in Section VII.
For Alternative 4, the Agency proposed a total cyanide limitation of
1.0 mg/1 based upon alkaline chlorination pilot plant data obtained
for Plant 0860B. This concentration is demonstrated to be achievable
by full scale operation at Plant 0860B and several pilot plant studies
conducted at other plants (0112D, 0684F, and 0860H).
Data for Plant 0860B demonstrate that the alkaline chlorination system
at this plant consistently removes cyanide to less than 1.0 mg/1 and
that activated carbon has virtually no effect on cyanide removal.
This is also demonstrated at Plant 0684F where activated carbon has
virtually no effect on cyanide removal from cokemaking wastewaters.
Phenols (4AAP) .
Again, Alternatives 2 and 3 provide no treatment for phenols (4AAP).
The effluent levels presented in Table X-1 do not reflect treatment
for phenols (4AAP).
For Alternative 4, the Agency proposed a BAT phenols (4AAP) limitation
based upon a concentration of 0.1 mg/1. Data obtained from pilot
plant studies conducted by the industry at Plant 0860H were used to
develop the proposed limitation. The achievability of the BAT
limitation is based upon pilot plant and full scale data for Plant
0860B (prior to adsorption on activated carbon) and pilot studies
conducted by the' industry and the Agency at Plants 0112D, 0684F, and
415
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0860H. The alkaline chlorination system installed at Plant.0860B
reduces phenols (4AAP) to the low ?g/l range prior to activated carbon
treatment. The phenols (4AAP) limitation for Alternative 5 are based
upon data from Plant 0860B after activated carbon treatment.
Toxic Metal Pollutants
The Agency reviewed long-term effluent data for filtration systems to
determine the toxic metals removal capabilities of these systems
(BAT-2) used in similar wastewater treatment applications. Available
data indicate a significant portion of the toxic metals in ironmaking
wastewaters are in particulate form and can be removed with the
suspended solids. In those instances in which the long-term data
(noted above and discussed in Volume I) are for ironmaking process
wastewater filtration applications, toxic metals removals are
generally based upon the degree of suspended solids removal
accomplished. The sampled plant monitoring data presented in Section
VII demonstrates this general pattern, although the toxic metals
effluent concentrations are generally slightly higher than the levels
expected strictly on the basis of the metal/TSS ratio.
Sedimentation and filtration are not effective for removing toxic
metals dissolved in process wastewaters. In order to remove both the
dissolved and particulate fractions of the toxic metals the Agency
considered lime precipitation and sedimentation (BAT Alternatives 3, 4
and 5). The presence of dissolved toxic metals in ironmaking
wastewaters is related to the nature of the process itself. Some of
the volatilized metals, -e.g., zinc, are not entirely transformed to
oxides and some of the metals may be present as fine particulates
measured as dissolved metals by the analytical methodology. The toxic
metals effluent levels which can be achieved by lime precipitation,
sedimentation, and filtration were determined on the basis of a review
of sampled plant monitoring data and data for Plant 0860B. Lead and
zinc are the toxic metal pollutants selected for limitation at BAT.
The Agency- based the lead limitation for Alternatives 3, 4, and 5 on
typical BPT blowdown levels and the zinc limitations are based upon
data from Plant 0860B.
Sulfide addition was also considered as a means of further reducing
the loadings of toxic metals. Because this technology has not bean
demonstrated in this subcategory and only marginal incremental toxic
metals removal can be realized, the Agency did not include sulfide
precipitation as a BAT model treatment technology.
Toxic Organic Pollutants
The removal of most toxic organic pollutants is accomplished in BAT
Alternative 4 (alkaline chlorination). Activated carbon treatment in
BAT Alternative 5 is designed specifically to remove residual levels
of those toxic organic pollutants which may be present after treatment
in BAT 4. Ironmaking wastewaters treated to the BPT level can contain
toxic organic pollutants (phenolic compounds, fluoranthene), that may
remain detectable after alkaline chlorination at concentrations at or
416
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near treatability levels. Also, application of BAT Alternative 4
could result in the formation of low levels of total halomethanes.
However, as noted in Section VII, the Agency believes that the proper
application of alkaline chlorination can minimize the formation of
trihalomethanes to levels of 0.1 mg/1 or less. These low levels are
generally not toxic to aquatic life and would not violate proposed
drinking water standards if found directly in water supply intakes.
Nonetheless, activated carbon treatment was considered as BAT
Alternative 5 for toxic organic pollutant removal.
The treatment capabilities of activated carbon are based upon pilot
plant studies and effluent data from Plant 0860B. The monitoring data
for Plant 0860B and a blast furnace, wastewater treatment pilot plant
study are presented in Tables VII-8, 9 and VII-.ll. Plant 0860B and
the pilot treatment system included alkaline chlorination and
activated carbon treatment components. The data for both of these
sources support the attainability of the effluent concentration for
phenols (4AAP) included in BAT Alternative 5. An avlrage phenols
(4AAP) effluent concentration of less than 0.05 mg/1 was achieved with
activated carbon during a pilot scale study at plant 0860H.
Total Residual Chlorine
A total residual chlorine limitation of 0.5 mg/1 daily maximum is
included in BAT 4 and 5 to control excess chlorine resulting from
alkaline chlorination. Several reducing agents can be used to destroy
excess chlorine. The chemistry of this reaction is well documented
throughout the literature and the technology is well demonstrated in
other industries as well as in this subcategory at Plant 0584C.
Discharge levels of total residual chlorine at plant 0584C are
consistently well below 0.5 mg/1.
Effluent Limitations for BAT Alternatives
The effluent limitations for the BAT alternative treatment systems
were developed on a mass basis (kg/kkg or lbs/1000 Ibs) by considering
the model plant effluent flow (70 gal/ton) and the respective BAT
effluent concentrations. The effluent limitations presented in Table
X-1 for each treatment alternative are on a mass basis, therefore, any
combination of effluent flows and concentrations may be used to attain
the specified -mass limitations. -
Selection of. a BAT Alternative
The Agency selected BAT Alternative 4, depicted in Figure X-1, as the
basis for the BAT limitations. The selection process included a
review of the treatability of the toxic pollutants considered for
limitation, the effluent levels of these pollutants in each treatment
alternative, and the costs of each alternative. With the exceptions
of BAT Alternatives 1, 5, and 6, the Agency determined that BAT
Alternative 4 provides the most significant benefits with respect to
the control of toxic pollutants. The Agency did not select BAT
Alternative 1 because slag evaporation cannot be used at all plants;
417
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Alternatives 5 and 6 were not selected on the basis of high
incremental costs and minimal additional pollutant removal over that
provided by Alternative 4. The pollutants of major concern are
ammonia-N, total cyanide, phenols (4AAP), and toxic metals. As shown
in Table X-l, the effluent levels of most of these pollutants are
reduced only at BAT Alternative 4. The formation of chlorinated
organics can be minimized to low levels with properly applied alkaline
chlorination systems. Thus, the costly activated carbon step included
in BAT Alternative 5 does not achieve significant incremental
pollutant removals. The Agency concludes that the effluent reduction
benefits associated with alkaline chlorination of blast furnace
wastewaters outweigh the negative aspects of the generation of low
levels of brominated and chlorinated compounds.
The achievability of the BAT limitations is well demonstrated by the
performance of Plant 0860B and by the pilot studies noted above. This
comparision is presented in Table X-2. Based upon data and
information ,~ available to the Agency, it is important that lime or
caustic addition and subsequent suspended solids removal precede
chlorination, both to insure proper control of pH and toxic metals,
and, to minimize the formation of trihalomethanes from the
chlorination reaction. The Agency believes that the reduction of
ammonia-N, cyanide, and phenols (4AAP) outweighs the formation of
halomethanes.
While BAT Alternative 1 is the least expensive alternative and
achieves the highest degree of treatment (i.e., no discharge of
process wastewater pollutants to navigable wasters), the Agency
concluded that this alternative cannot serve as the basis, for BAT
effluent limitations for the entire subcategory. Due to the methods
of slag handling (i.e., remote from the blast furnace) this technology
cannot be used at some plants. However, as noted in Section VIII, the
Agency believes that BAT Alternative 1 may be selected for many plants
as the least expensive means of achieving the BAT limitations.
Approximately 60% of the plants have slag operations adjacent to the
blast furnaces. The Agency is also aware of other treatment
technologies that may be innovative for treating ironmaking
wastewaters to achieve the BAT limitations at less cost. These
technologies involve reducing recycle system blowdowns to minimum
levels with subsequent blowdown treatment.
413
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JRONMAKING SUBCATEGORY
SECTION XI
BEST CONVENTIONAL POLLUTANT CONTROL TECHNOLOGY (BCT)
Introduction
44501, July 30, 1979) .
co,-t-i«n Vru(b) (4) (B) , the Act requires that BCT
case may BCT be less stringent than BPT.
had argued that a second cost test was not required.)
BCT limitations until EPA proposes the revised BCT methodology.
423
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-------
IRONMAKING SUBCATEGORY
SECTION XII
EFFLUENT, QUALITY ATTAINABLE THROUGH THE
APPLICATION OF NEW SOURCE PERFORMANCE STANDARDS
Introduction
NSPS are based upon effluent quality achievable through the
application of Best Available Demonstrated Control Technology (BDT),
processes, operating methods, or other alternatives, including, where
practicable, a standard permitting no discharge of pollutants.
Identification of NSPS
The seven alternative treatment systems developed for NSPS shown in
Figure XI1-1 are the same as the BPT and BAT alternative treatment
systems except filtration is included in the alkaline chlorination
alternative. The corresponding effluent standards for these treatment
alternatives are presented in Table"XII-T.. Following is a summary of
the treatment technologies included in each NSPS treatment
alternative: ' . *
NSPS - 1
NSPS
NSPS
NSPS
_ o
- 4
NSPS - 5
NSPS
Gravity sedimentation in a thickener, coagulant
aid addition, vacuum filtration of sludges, and
recycle through a cooling tower. The recycle
system blowdown is discharged without further
treatment.
is
The blowdown from the recycle system of NSPS 1
minimized and evaporated on slag.
The recycle system blowdown undergoes filtration
prior to discharge.
The recycle system blowdown is treated by lime
precipitation and sedimentation in an inclined
plate separator prior to discharge.
The recycle system blowdown is treated by lime
precipitation and two-stage alkaline chlorination
followed by filtration and dechlorination.
The effluent from the
chlorination/dechlorination system of
treated by activated carbon.
alkaline
NSPS 5 is
425
-------
NSPS - 7
The recycle system blowdown is processed by vapor
compression distillation to achieve zero
discharge.
Rationale for Selection of NSPS 3 .
Since, except as noted above, the NSPS treatment alternatives are the
same as the BPT and BAT treatment systems, the rationale presented in
Sections IX and X for these systems is applicable to NSPS.
All of the NSPS treatment schemes are addressed collectively below.
Treatment Technologies
As noted in previous sections, the treatment technologies included in
the NSPS alternative treatment systems are demonstrated within the
ironmaking subcategory or transferred from other subcategories or
related industries (as discussed in Section X). The model treatment
technologies are applicable for NSPS for ironmaking wastewaters.
The resulting effluent quality for the NSPS treatment alternatives are
presented in Table XII-1. 'As noted in Section X, the critical
pollutants and their effluent levels are based upon the demonstrated
capabilities of the wastewa'ter treatment technologies. The effluent
levels for suspended solids are based on the performance of Plant
0860B and long term effluent data" for clarification and filtration
systems applied to ironmaking and other similar wastewaters. The data
for Plant 0860B are presented in Table VII-11 while the supplemental
long term data-analysis is set out in Appendix A of Volume I. These
data clearly demonstrate the achievability and appropriateness of the
NSPS effluent levels.
Another available technology is nonevaporative cooling of blast
furnace wastewaters. This system has the potential for extremely low
blowdown rates, or, possibly, zero discharge. This technology .is
installed at two plants and is currently being installed at others.
Flows
The applied and discharge flows developed for BPT and BAT ar%
applicable and are included in all NSPS treatment alternatives. As
noted in Section X, the treatment model effluent (blowdown) flow of 70
gal/ton has been demonstrated on the basis ' of long-term data at
several plants.
Selection of an NSPS Alternative
The Agency selected NSPS 5, depicted in Figure XII-1, as the NSPS
model treatment system. This alternative was selected for the same
reasons presented in Section X regarding the selection of the BAT
model treatment system. However, the NSPS model treatment, system
includes filtration for additional suspended solids removal. As noted
for BAT, evaporation of the recycle system blowdown to extinction on
426
-------
slag is a means of attaining NSPS. The NSPS are presented in Table
XII-1 under the heading of NSPS 5.
The NSPS standards are clearly demonstrated by the - performance of
Plant 0860B. This comparision is presented in Table XII-2.
427
-------
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430
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IRONMAKING SUBCATEGORY
SECTION XIII
PRETREATMENT STANDARDS FOR DISCHARGES TO
PUBLICLY OWNED TREATMENT WORKS
Introduction
This section presents alternative pretreatment systems for blast
furnace operations with discharge to publicly owned treatment works
(POTWs). The blowdowns from two ironmaking operations are discharged
to POTWs. The general pretreatment and categorical pretreatment
standards applying to ironmaking operations are discussed below.
General Pretreatment Standards
For detailed information on Pretreatment Standards refer to 46 FR 9404
et seq "General Pretreatment Regulations for Existing and New Sources
of Pollution," (January 28, 1981). See also 47 FR 4518 (February 1,
1982). In particular, 40 CFR Part 403 describes national standards
(prohibited and categorical standards), revision of categorical
standards through removal allowances, and POTW pretreatment programs.
In establishing pretreatment standards for ironmaking operations, the
Agency considered the objectives . and requirements of the General
Pretreatment Regulations. The Agency determined that untreated
discharges of ironmaking wastewaters to POTWs would result in pass
through of toxic pollutants.
Identification of_ -Pretreatment Alternatives
The PSES and PSNS alternative treatment systems are identical to the
BPT and the BAT alternative treatment systems presented in Sections IX
and X. These alternatives are shown in Figure VIII-1. Reference is
made to Sections X and XII for a discussion of these treatment
systems.
Following is a summary of the treatment system components included in
each pretreatment alternative:
PSES/PSNS Alternative 1 -
Coagulant aid addition, gravity
sedimentation in a thickener, vacuum
filtration of sludges, recycle (98%) through
a cooling tower. The blowdown from the
recycle system is discharged without further
treatment.
PSES/PSNS Alternative 2 - The recycle system blowdown from
Alternative 1 is completely evaporated on
slag. .
431
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PSES/PSNS Alternative 3 - This alternative is the same as
Alternative 2 except that the blowdown is
treated by filtration and discharged, rather
than evaporated on slag.
PSES/PSNS Alternative 4 - The recycle system blowdown is treated
by lime precipitation and sedimentation in an
inclined plate separator prior to discharge.
PSES/PSNS Alternative 5 - The recycle system blowdown is treated
by two-stage alkaline chlorination prior to
discharge.
PSES/PSNS Alternative 6 - The effluent from the alkaline
chlorination system of Alternative 5 is
further treated by filtration and- activated
carbon.
PSES/PSNS Alternative 7 - " The recycle system blowdown is processed
by vapor compression distillation to achieve
zero discharge.
The intent of the pretreatment standard is to provide for reductions
in the effluent levels of .ammonia, cyanide, toxic metals, and toxic
organic pollutants. Recycle of the wastewaters will substantially
reduce the pollutant loads discharged from blast furnaces.
Evaporation on slag, although not universally applicable, eliminates
the discharge of the blowdown. Filtration and lime precipitation are
included for the purpose of reducing toxic metals effluent levels. As
noted in Section X, the major portion of the toxic metals waste load
is entrained in the particulate matter suspended in the process
wastewaters. Consequently, suspended solids control by sedimentation
and filtration will result in the removal of a substantial portion of
the toxic metals load. Lime precipitation will provide additional
toxic metals removal and load reductions through precipitation of
those toxic metals dissolved in the wastewaters. Two-stage alkaline
chlorination technology.is included to remove ammonia-N, cyanide, and
phenols (4AAP). Activated carbon provides additional removal of toxic
organics that may remain in the wastewater after alkaline
chlorination.
Table XIII-1 presents the effluent standards for each alternative
those pollutants considered for regulation.
Selection of Pretreatment Alternatives
for
™ Alternative 5 was selected as the basis for the promulgated
PSES and PSNS. As noted earlier, PSES/PSNS Alternative 5 is
equivalent to the selected BAT alternative for ironmak'ing operations
This alternative provides for the greatest removal of toxic and
nonconventional pollutants found in ironmaking wastewaters without the
high costs of activated carbon and zero discharge technologies
included in Alternatives 6 and 7, respectively.
432
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Aside from recycle (PSES/PSNS Alternative 2), there is no specific
treatment in the BPT system for toxic and rionconventional and
pollutants; nor is there any in PSES/PSNS Alternatives 3 and 4. Thus,
the Agency believes PSES/PSNS Alternative 5 is the appropriate model
technology for PSES/PSNS. The removal rates of toxic and
nonconventional pollutants from untreated ironmaking wastewaters for
PSES/PSNS Alternative 5 are compared to the POTW removal rates for
these pollutants:
. Pollutant Removal Rate.Comparison
Ammonia-N
Cyanide
Lead
Zinc
PSES/PSNS
Model '
99.3%
99>9%
99.9%
99.9%
Actual
POTW
0%
52%
47%
65% .
As shown above, the selected PSES/PSNS alternative will prevent pass
through' of toxic and nonconventional pollutants found in ironmaking
wastewaters to a significantly greater degree than would occur if
ironmaking wastewaters were discharged untreated to POTWs. The
achievability of these standards is demonstrated in Table X-2. .The
model treatment system is depicted in .Figure XIII-1 and PSES and PSNS
are shown in Table XIII-1. •;
433
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*U.S. GOVERNMENT PRINTING OFFICE: 1982-O-36l-OS5/kb52
435
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