44Q177087A
Supplement For
PRETREATMENT
to the
Development Document
for the
INORGANIC CHEMICALS
MANUFACTURING
POINT SOURCE CATEGORY
\
S
U.S. ENVIRONMENTAL PROTECTION AGENCY
JULY 1977
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SUPPLEMENT FOR PRETREATMENT
TO THE DEVELOPMENT DOCUMENT
FOR TEE
INORGANIC CHEMICALS MANUFACTURING
POINT SOURCE CATEGORY
Douglas M. Costle
Administrator
Thomas C. Jorling
Assistant Administrator
for Water and Hazardous Materials
Eckardt C. Beck
Deputy Assistant Administrator
for Water Planning and Standards
Robert B. Schaffer
Director
Effluent Guidelines Division
Elwood E. Martin
Project Officer
July 1977
Effluent Guidelines Division
Office of Water and Hazardous Materials
U.S. Environmental Protection Agency
Washington, D.C. 20460
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ABSTRACT
This document presents the findings of a study by the
Environmental Protection Agency of the inorganic chemical
industry for the purpose of developing pretreatment
standards for existing sources to implement section 307 (b)
of the Federal Water Pollution Control Act, as amended.
The development of data and identified technology presented
in this document relate to waste waters generated in the
following specific segments of the inorganic chemical
industry: aluminum chloride, aluminum sulfate, calcium
carbide, calcium chloride, copper sulfate, ferric chloride,
lead oxide, nickel sulfate, nitrogen, oxygen, potassium
dichromate, potassium iodide, silver nitrate, sodium
bicarbonate, and sodium fluoride. The pretreatment levels
corresponding to these technologies also are presented.
Supporting data and rationale for development of
pretreatment levels based on best practicable pretreatment
technology are contained in this report.
iii
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CONTENTS
Section Page
I CONCLUSIONS 1
II RECOMMENDATIONS 5
III INTRODUCTION 9
IV INDUSTRY SUBCATEGORIZATIQN 53
V WASTE CHARACTERIZATION 67
i VI\ SELECTION OF POLLUTANT PARAMETERS 137
VII CONTROL AND PRETREATMENT TECHNOLOGY 151
VIII COST, ENERGY, AND IMPLEMENTATION 211
IX BEST PRACTICABLE PRETREATMENT TECHNOLOGY 249
X ACKNOWLEDGMENTS 259
XI REFERENCES 261
XII GLOSSARY 263
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FIGURES
No. Title Page
1 Flow Diagram for Typical Production of Anhydrous 16
Aluminum Chloride
2 Flow Diagram for Typical Production of Hydrous 1?
Aluminum Chloride
3 Flow Diagram for Typical Production of Aluminum (9
Sulfate
4 Flow Diagram of Standard Process for Production 22
of calcium carbide
5 Flow Diagram for Production of Calcium Chloride 23
from Natural Brine (Plant 19404)
6 Generalized Flow Diagram for Production of Calcium 25
Chloride from Calcium Carbonate
7 Flow Diagram for Production of High-Purity Calcium 26
Chloride (Plant 19406)
8 Flow Diagram of Standard Process for Production 28
of cupric Sulfate
9 Flow Diagram of Process for Manufacture of Cupric 29
Sulfate Solution
10 Flow Diagram for Typical Production of Ferric 31
Chloride
11 Flow Diagrams of Four Alternative Processes for 33
Production of Lead Monoxide Using Air
Oxidation of Lead
12 Flow Program for Typical Production of Nickel 36
Sulfate
13 Flow Diagram of Typical High-Pressure Air-separa- 38
tion Process (Modified Claude Cycle) for
Production of Nitrogen and oxygen
14 Flow Diagram of Low-Pressure Air-Separation 39
Process (Modified Linde-Frankl cycle) Used in
Typical Production of Nitrogen and Oxygen
15 Flow Diagram for Typical Production of Potassium 42
Dichrornate
16 Flow Diagram of iodine/Potassium Hydroxide Process 44
for Production of Potassium Iodide and By-
product Potassium lodate
17 Flow Diagram of Iron Carbonate Process for 45
Production of Potassium Iodide
18 Flow Diagram of Iron~Catalyst Process for 46
Production of Potassium Iodide
19 Flow Diagram for Typical Production of silver 48
Nitrate
20 Simplified Flow Diagram of Solvay Process for 50
Production of Sodium Bicarbonate
21 Generalized Flow Diagram for Production of 52
Sodium Fluoride
vii
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FIGURES (cent.)
No. Title Page
22 Flow Diagram Showing Typical Water Use in 70
Production of Aluminum Chloride (Plant 19101)
23 Plow Diagram showing Generalized Sources and 74
Uses of Water
24 Flow Diagram for Production of Calcium Carbide 79
Showing Water Use (Plant 19301)
25 Flow Diagram Showing Water Balance for Production 81
of Calcium Chloride from Natural Brine
(Plant 19404)
26 Flow Diagram for Production of Cupric sulfate 84
(Plant 19506)
27 Flow Diagram for Production of Cupric Sulfate 88
(Plant 19505)
28 Flow Diagram for Production of Ferric chloride 89
(Plant 19601)
29 Flow Diagram for Production of Ferric chloride 90
(Plant 19602)
30 Flow Diagram for Production of Lead Monoxide 97
(Plant 19701)
31 Flow Diagram for Production of Lead 98
Monoxide (Plant 19702)
32 Flow Diagram for Production of Nickel Sulfate 105
(Plant 19801)
33 Flow Diagram for Production of Nickel Sulfate 107
(Plant 19803)
34 Flow Diagram showing Generalized Waste Water 113
Flows in Production of Nitrogen and Oxygen
35 Flow Diagram for Production of Silver Nitrate 120
(Plant 20201
36 Flow Diagram for Production of Silver Nitrate 121
(Plant 20202)
37 Flow Diagram of Solvay process for Production 123
of Sodium Bicarbonate (Plant 12101)
38 Flow Diagram for Production of Sodium Fluoride 128
(Plant 20301)
39 Flow Diagram for Production of Sodium Fluoride t29
(Plant 20302)
40 Flow Diagram for Production of Sodium Fluoride 132
(Plant 20303)
41 Minimum pH Value for Complete Precipitation of 158
Metal Ions as Hydroxides
42 Flow Diagram Showing Scrubber-Water Reuse in 162
Production of Hydrous Aluminum Chloride
(Plant 19103)
V3 Flow Diagram Showing Waste Water Treatment Used in 164
Production of Aluminum Chloride (Plant 19101)
44 Flow Diagram showing Waste Water Treatment used in 166
viii
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FIGURES (cont,)
No. Title Page
Production of Aluminum Chloride (Plant 19104)
45 Plow Diagram of Waste Water-Recycling System Used 168
in Production of Aluminum Sulfate (Plant 19201)
46 Flow Diagram of Waste Water-Recycling System Used 169
in Production of Aluminum Sulfate (Plant 19205)
47 Plow Diagram for Production of Calcium Carbide 172
(Plant 19303)
48 Plow Diagram Showing Pretreatment of Emissions- 174
Scrubber Water Used in Production of Calcium
Chloride (Plant 19406)
49 Plow Diagram Showing Typical Waste Water Pretreat- 177
ment Used in Production of Ferric Chloride
50 Plow Diagram of Waste Water-Treatment System 181
Used in Production of Lead Monoxide
(Plant 19702)
51 Plow Diagram Showing Typical Waste Water Pre- 185
treatment Used in Production of Nickel
Sulfate (Plant 19801)
52 Plow Diagram Showing Waste Water Pretreatment 186
Used in Production of Nickel Sulfate
(Plant 19803)
53 Flow Diagram Showing Pretreatment of Waste Water 191
in Production of Nitrogen and Oxygen
(Plant 13102)
54 Plow Diagram of Oil-separation Process for Treat- 193
ment of Compressor-Condensate Waste Water in
Production of Nitrogen and Oxygen (P3.ant 13101)
55 Flow Diagram Showing Waste Water Pretreatment 200
Used in Production of Silver Nitrate
(Plant 20201)
56 Flow Diagram of Waste Water-Treatment System 206
Used in Production of sodium Fluoride
(Plant 20302)
57 Flow Diagram of Central Waste Water-Treatment 207
System Used in Production of Sodium Fluoride
(Plant 20303)
58 Treatment-System Costs 233
59 Settling/Holding-Tank Costs 235
60 Thickener Costs 236
61 Daily Savings Achieved by Volume Reduction of 237
Sludge Based on Disposal Cost of $50/cubic
meter ($38/cubic yard)
62 Centrifuge Costs 239
63 Sand-Filter Costs 241
64 Mixing-Tank Costs 242
65 Pump Costs 243
XX
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TABLES
No, Title Page
1 Number of Plants and Discharge Type by Chemical 2
Subcategory
2 Pretreatment standards 6
3 Summary of subcategories Recommended for 66
Inorganic Chemical Industry
4 Raw Waste Characteristics of Chlorine-Demagging 71
Scrubber Waste Water from secondary Aluminum
Industry
5 Chemical Composition of Combined Raw Waste Waters 73
from Production of Aluminum Chloride
(Plant 19102)
6 Chemical Compositions of Raw Waste Waters from 76
Production of Aluminum Sulfate
7 Characteristics of Plants Producing Calcium 78
Carbide
8 characteristics of Plants Producing Cupric 86
Sulfate
9 Chemical Composition of Typical Iron Pickle 93
Liquor from Production of Ferric Chloride
10 Chemical Composition of Average Waste Water from 95
Production of Ferric Chloride (Plants with
Large Leaks and Spills)
11 chemical composition of Average Waste Water from 96
Production of Ferric Chloride (Plants with
Minimal Leaks and Spills)
12 Estimated Chemical Composition of Untreated 101
Washdown Waste Water from Production of Lead
Monoxide (Plant 19702)
13 Chemical Composition of Slowdown from Typical 103
Reciprocating-Piston compressor (Plants
Producing Lead Monoxide)
14 Chemical Compositions of Raw Waste Waters from 109
Production of Nickel Sulfate (Three Plants)
15 Chemical Compositions of Individual Process 110
Waste streams from Production of Nickel
Sulfate (Plant 19801)
16 Chemical Composition of Waste Loading for 114
Untreated Compressor-Condensate Stream from
Production of Nitrogen and Oxygen (Plant 13101)
17 Estimated Chemical Characteristics of Untreated 126
Slurry Thickener overflow from Production of
Sodium Bicarbonate (Plant 12101)
18 Chemical Composition of Untreated Waste Water 131
from Production of Sodium Fluoride
(Plant 20302)
19 Water Consumption of Processes for production of 134
Sodium Fluoride (Three Plants)
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TABLES (COnt.)
NO»:;- Title .f. _ Page
20 Chemical Composition of Treated Waste Water from 165
Production of Aluminum Chloride (Plant 19101)
21 Incidental Removals of Pollutant Parameters 167
22 Chemical compositions of Average Treated Waste 179
Waters from Production of Ferric Chloride
23 Chemical Compositions of Raw and Treated Waste 182
Waters from Production of Lead Monoxide
(Plant 19702)
24 Chemical Compositions of Treated Waste Waters 187
from Production of Nickel Sulfate
(Two Plants)
25 Effluent Limitations Imposed by Publicly Owned 189
Treatmen
26 Chemical Compositions of and Waste Loadings for 194
Compressor-Condensate Waste Water from Pro-
duction Proof Nitrogen and Oxygen Before and
After Treatment by Oil-Separation Process
(Plant 13101)
27 Chemical Composition of Treated Waste Water Dis- 199
charged From Production of Silver Nitrate
(Plant 20201)
28 Effects of Treating Waste Water by Settling in 203
Production of Sodium Bicarbonate (Plants
12101 and 12102)
29 Chemical compositions of Saw and Treated Waste 208
Waters from Production of Sodium Fluoride
and Other Chemicals (Plant 20303)
30 Model-Plant Control Costs for Aluminum Chloride 213
Industry - Proposed Pretreatment
31 Model-Plant Control Costs for Aluminum Chloride 21ft
Industry - Alternate Pretreatment
32 Model-Plant Control Costs for Aluminum Sulfate 216
Industry - Proposed Pretreatment
33 Model-Plant Control Costs for Aluminum Sulfate 217
Industry - Alternative Pretreatment
3ft Model-Plant Control Costs for Copper (Cupric) 218
Sulfate Industry
35 Model-Plant control Costs for Iron (Ferric) 220
Chloride Industry - Proposed Pretreatment
36 Model-Plant Control Costs for Iron (Ferric) 221
Chloride Industry - Alternative Pretreatment
37 Model-Plant Control Costs for Lead Monoxide 222
Industry
xii
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TABLES (cont.J
No. Title Page
38 Model-Plant Control Costs for Nickel Siilf ate 224
Industry
39 Model-Plant control Costs for Nitrogen and 225
Oxygen Industry
40 Model-Plant control Costs for Potassium 227
Bichromate industry
41 Model-Plant Control Costs for silver Nitrate 229
Industry
42 Model-Plant Control costs for Sodium Fluoride 230
Industry
43 Rotary Vacuum-Filter Costs 238
44 Installed-Pipe costs 244
xiii
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SECTION I
CONCLUSIONS
For the purpose of establishing effluent limitations
guidelines and standards of performance, the Inorganic
Chemicals Manufacturing Point Source category was divided'
into Major and Significant Inorganic Products. This report
deals with fifteen segments of the Major and Significant
Inorganic Products Categories which may discharge process
wastewater to Publicly owned Treatment Works (POTWs) and for
which effluent limitations guidelines and standards have
been promulgated.
The fifteen product segments covered in this document are:
aluminum chloride (A1C13), aluminum suf ate (A12 (S0j») 3),
calcium carbide (CaC2) ,~* calcium chloride (CaC12)"» copper
sulfate (CuSOU), ferric chloride (PeC13), lead monoxide
(PbO) , nickel sulfate (Nisof*), nitrogen (N2), oxygen (O2),
potassium dichromate (K2Cr2O7jt potassium iodide {KJ.),
silver nitrate (AgNO^), sodium bicarbonate (NaHCO^), and
sodium fluoride (NaF)."" ""
For the purpose of establishing pretreatment standards, that
portion of the industry included in this report is
subcategorized by chemical product, with the exception of
nitrogen and oxygen which are combined into one subcatgory.
The consideration of factors such as geographic location,
land availability, plant size, process(es), waste water
treatment and control techniques employed, and the types of
POTW receiving the discharges support these conclusions.
Distinctions between wastes produced by each product segment
and the control and treatment techniques available to reduce
the discharge of pollutants to POTW further support the
subcategorization chosen.
Available data from chemical industry directories and
contacts with industry on the discharge type and number of
plants within each chemical subcategory are presented in
Table 1. On the basis of information available at this
time, it is apparent that only a small percentage of the
industry discharges process waste water to POTWs.
Historical data from the literature, information supplied by
industry, and data collected during on-site visits were
compiled and evaluated pursuant to development of
pretreatment standards for each of the chemical
subcategOries. Based on the information collected, the
major types and characteristics of process waste water
generated have been identified, existing and potential
pretreatment technologies have been described, and costs
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TABLE 1. NUMBER OF PLANTS AND DISCHARGE TYPE BY CHEMICAL SUBCATEGQRY
CHEMICAL SUBCATEGORY
Aluminum chloride
Aluminum sulfate
Calcium carbide
Calcium chloride
Copper fcupric) sulfate
Ferric (iron) chloride
Lead monoxide
Nickel sulfate
Nitrogen and Oxygen
Potassium dichromate
Potassium iodide
Silver nitrate
Sodium bicarbonate
Sodium fluoride
TOTAL NO.
OF PLANTS
13
84
4
12
16
21
17
11
193
1
4
3
3
4
NO, OF DIRECT
DISCHARGERS
3
8
1
3
8
3
1
1
71
1
1
1
2
2
NO. OF ZERO
DISCHARGERS
5
13
2
2
4
2
3
0
1
0
1
1
1
2
NO. OF POTW"
DISCHARGERS
0
0
0
1
0
2
0
3
33
0
2
0
0
0
NO. OF UNKNOWN
DISCHARGERS
i
63
1
6 ;
4
14 ;
13
7
88
0
0
1
0
0
•Publicly owned treatment works
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accrued by implementation of these technologies have been
assessed. Where data for actual POTW dischargers was
lacking, data on direct dischargers were used to
characterize the industry.
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SECTION II
RECOMMENDATIONS
These regulations establish two sets of pretreatment
requirements for the subcategories mentioned. The first
set, the "prohibited discharge** standards, are designed to
prevent inhibition of, or interference with, the municipal
treatment works, by prohibiting the discharge of pollutants
of a nature or in a quantity that would endanger the
mechanical or hydraulic integrity of the works. Except for
minor changes, these prohibited discharge standards are
identical to the prohibitions contained in the general pre-
treatment regulation now found in (10 CFR 128.131). The
"prohibited discharge" standards are as follows: No
pollutant (or pollutant property) introduced into a publicly
owned treatment works shall interfere with the operation or
performance of the works. Specifically, the following
wastes shall not be introduced into the publicly owned
treatment works:
1. Pollutants which create a fire or explosion hazard
in the publicly owned treatment works.
2. Pollutants which will cause corrosive structural
damage to treatment works, but in no case
pollutants with a pH lower than 5.0, unless the
works is designed to accommodate such pollutants.
3. Solid or viscous pollutants in amounts which would
cause obstruction to the flow in sewers, or other
interference with the proper operation of the
publicly owned treatment works.
4. Pollutants at either a hydraulic flow rate or
pollutant flow rate which is excessive over
relatively short time periods so that there is a
treatment process upset and subsequent loss of
treatment efficiency,
The second set of standards, known as categorical pretreat-
ment standards, contain specific numerical limitations based
on an evaluation of available technologies in a particular
industrial subcategory. The specific numerical limitations
are arrived at separately for each subcategory, and are
imposed on pollutants or pollutant properties which may
interfere with, pass through, or otherwise be incompatible
with publicly owned treatment works. These pretreatment
standards are presented in Table 2.
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TABLE £ SUMMARY OF PRETREATMEIMT STANDARDS FOR SEVERAL
SUBCATEGORIES OF THE INORGANIC CHEMICALS INDUSTRY
SUBC ATE GORY
ALUMINUM CHLORIDE
ALUMINUM SULFATE
COPPER SULFATE
FERRIC CHLORIDE
LEAD MONOXIDE
NICKEL SULFATE
POTASSIUM DICHROMATE
SILVER NITRATE
SODIUM FLUORIDE
PARAMETER
pH (range)*
Zn
Cu
N>
Cr (hex)
Cr (total)
Cu
Ni
Zn
Pb
Ni
Cu
Cr (hex)
Cr (total)
Ag
Fluoride
PRETREATMENT STANDARD (mg/l)
Maximum for any
one day
6.0 - 10.0
5,0
1.0
2,0
0.18
1.8
1.0
2,0
5,0
2.0
2.0
1.0
0.18
1.8
1.0
50.0
Average of daily value*
for 30 consecutive
day) not to exceed
5.0 • 10.0
2J
0.5
1.0
0.09
0.9
o.§
1.0
2.5
1.0
1.0
0.6
0.09
O.t
o.p
25.0
*pH units
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In addition, as guidance for local POTW. author it ie§f: zinc
limits of 2.5 mg/1 (30 day average} and 5.0 mg/1 (daily
maximum) are recommended for discharges from aluminum
chloride manufacturing plants.
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SECTION III
INTRODUCTION
PURPOSE AMD AUTHORITY
General • .
The Environmental Protection Agency (EPA or Agency) is
developing regulations concerning pretreatment standards for
existing sources and pretreatment standards for new sources
pursuant to Sections 307 (b) and (c) of the Federal Water
Pollution Control Act, as amended (33 U.S.C. 1317 (b) and (c}
86 Stat, 816 et seq., P.L. 92-500) (the Act). These
regulations would replace the existing regulations on
pretreatment standards by establishing specific pretreatment
standards for the several segments of the Inorganic Chemical
Industry. The specific chemical segments included in this
document are; aluminum chloride (A1C13) , aluminum sulfate
(A12. (SOjl) 3J , calcium carbide (CaC2> , calcium chloride
(CaCl2), copper sulfate (CuSOj|) , ferric chloride (FeClf) ,
lead ""oxide (PbQ) , nickel sulfate (BiSO4) , nitrogen (N2) ,
oxygen (O2) , potassium dichromate (~K2Cr2OT) » potassium
iodide (KI) , silver nitrate (AgNO3) ,"" sodXum bicarbonate
(NaHCO3_) t and sodium fluoride (NaF).
Legal Authority
Section 307(b) of the Act requires the Administrator to
promulgate regulations establishing pretreatment standards
for the introduction of pollutants into treatment works
which are publicly owned for those pollutants which are
determined not to be susceptible to treatment by such
treatment works, or which would interfere with the operation
of such treatment works, Pretreatment standards established
under this section shall be established to prevent the
discharge of any pollutant into treatment works which are
publicly owned, which pollutant interferes with, passes
through, or otherwise is incompatible with such works.
Section 307 (c) provides that the Administrator shall
promulgate pretreatment standards for any source which would
be a new source subject to Section 306 if it were to
discharge pollutants to navigable waters, simultaneously
with the promulgation of standards of performance under
section 306 for the equivalent category of new sources.
Such pretreatment standards shall prevent the discharge of
any pollutant into such treatment works, which pollutant may
interfere with, pass through, or otherwise be incompatible
with such works.
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Purpose of Proposed Regulations
Subsequent to the promulgation of pretreatment standards (40
CFR 128) on November 8, 1973, the Agency has proposed and
promulgated numerous pretreatment standards relative to
specific industry category waste water discharges for both
existing sources and new sources.
Additionally, the Agency plans to clarify and simplify the
existing pretreatment standards. General provisions
regulations (40 CFR 403) have been proposed which cover both
existing sources and new sources. The general provisions
regulations set forth the basis for pretreatment standards
and certain general prohibitions. specific numerical
pretreatment limitations for particular pollutants will be
set forth in the same subpart as the effluent limitations
and new source performance standards for the industry
subcategory to be regulated.
The new regulations establish two sets of pretreatment
standards under the authority of Section 307 (b) of the Act.
The first set, known as prohibited discharge standards, are
designed to prevent inhibition or interference with the
municipal treatment works by prohibiting the discharge of
pollutants of such nature or quantity that the mechanical or
hydraulic integrity of the publicly owned treatment works is
endangered. These prohibited discharge standards, with
minor changes, are identical to the prohibitions contained
in the general pretreatment regulation now found at 40 CPR
128.131. The second set, known as categorical pretreatment
standards, apply to existing sources in this specific
industrial subcategory. These standards contain numerical
limitations based upon available technologies to prevent the
discharge of any pollutant into a PQTW, which pollutant may
interfere with, pass-through or otherwise be incompatible
with such works.
With respect to the subcategories governed by these
regulations, the general pretreatment requirements set forth
in 40 CPR Part 128 are superseded. Those requirements were
proposed on July 19, 1973 (38 PR 19236) and published in
final form on November 8, 1973 (38 FR 30982). They limit
the discharge of pollutants which pass through or interfere
with the operation of publicly owned treatment works, but do
not set numerical limitations or explicitly list particular
pollutants to be regulated. The provisions of the present
regulation overlap to a considerable degree with the
language of the general pretreatment requirements, while at
the same time setting specific numerical limitations on
certain pollutants. Por the purpose of clarity, sources
affected by the present regulation are exempted from 40 CFR
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Part 128. This decision 'is particularly warranted, because
the provisions of 40 CPR Part 128 have sometimes been a
source of confusion in the past, and because new general
pretreatment regulations have been proposed (42 FR 6476,
February 2, 1977) which will revoke and replace 40 CFR Part
128 upon promulgation.
Statutory Consi dera t ions
The Federal Water Pollution control Act Amendments of 1972,
33 Q»S,C. Section 1251 et seq.r were designed by Congress
to achieve an important objective—to "restore and maintain
the chemical, physical, and biological integrity of the
Nation's waters." Primary emphasis for attainment of this
goal is placed upon technology based regulations.
Industrial point sources which discharge into navigable
waters must achieve limitations based on Best Practicable
Control Technology currently Available (BPCTCA) by July 1.
1977 and Best Available Technology Economically Achievable
(BATEA) by July 1, 1983 in accordance with Sections 301 (b)
and 304 (b), New sources must comply with New Source
Performance standards (NSPS) based on Best Available
Demonstrated control Technology (BADCT) under Section 306.
Publicly owned treatment works (POTW) must meet "secondary
treatment" by 1977 and best practicable waste treatment
technology by 1983 in accordance with Section 301(b) and
201 (g) (2) (A).
Users of a POTW also fall within the statutory scheme as set
out in Section 301 (b). Such sources must comply with
pretreatment standards promulgated pursuant to Section 307.
Sections 307(b) and (c) are the key sections of the Act in
terms of pretreatment. Both provide that the basic purpose
of pretreatment is "to prevent the discharge of any
pollutant through treatment works...which are publicly
owned, which pollutant interferes with, passes through, or
otherwise is incompatible with such works." The intent is
to require treatment at the point of discharge complementary
to the treatment performed by the POTW. Duplication of
treatment is not the goal; as stated in the Conference
Report (H.R. Rept. No. 92-1465, page 130), "In no event is
it intended that pretreatment facilities be required for
compatible wastes as a substitute for inadequate municipal
waste treatment works." On the other hand, pretreatment by
the industrial user of a POTW of pollutants which are not
susceptible to treatment in a POTW is absolutely critical to
attainment of the overall objective of the Act, both by
protecting the POTW from process upset or other
interference, and by preventing discharge of pollutants
which would pass through or otherwise be incompatible with
11
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such works. Thus, the mere fact that an industrial source
utilizes a publicly owned treatment works does not relieve
it of substantial obligations under the Act. The purpose of
this regulation is to establish appropriate standards for
several segments of the Inorganic Chemical Industry.
In determining numerical pretreatment standards, the initial
step was to classify the pollutants discharged by a source
to a POTW in terms of the statutory criteria of
interference, pass through, or other incompatible effect.
These pollutants fall, generally, into three classes. The
first class is composed of those pollutants which are
similar, in all material respects, to the pollutants which
are found in municipal sewage and which the typical POTW is
designed to treat. For such pollutants, no national
pretreatment standards will be established. The second
class of pollutants has those which, in large quantities,
would interfere with the operation of a POTW but which would
be adequately treated by the POTW when received in limited
quantities. Such pollutants will be subject to pretreatment
standards designed to allow their release into the POTW in
treatable amounts.
Finally, the third class of pollutants includes those which
are of a nature that would require the maximum feasible
pretreatment to prevent interference with the POTW or pass
through of the pollutant or other incompatibility. Such
pollutants will be subject to pretreatment standards based
upon the practical limits of technology.
In assessing the capabilities of POTWs and the effect upon
them of various pollutants, the Agency, because it is
developing uniform national standards, has focused upon the
typical biological treatment system. Provision will be made
for variances to standards, where appropriate, for users of
a POTW where the POTW is of a fundamentally different nature
from those on which the standards were based.
For the purpose of establishing technology-based
pretreatment standards for industrial users of a POTW, the
Agency has utilized, together with other pertinent data, the
information developed in the course of establishment of
effluent limitations and new source performance standards
for the corresponding industrial point-source categories.
While differences, particularly in terms of economic or
technical parameters, between direct dischargers and users
of a POTW will be considered, technology based pretreatment
standards for existing sources will often tend to reflect
BPCTCA. Although the Act does not elaborate upon the
criteria to be applied in establishing numerical
pretreatment standards, the purposes of the Act, and maximum
12
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equity between direct and indirect dischargers, will be best
attained through use of this BPCTCA analogy. Where, in
particular, a pollutant passes through a POTW untreated or
inadequately treated, the source discharging such a
pollutant causes essentially the same environmental insult
as a direct discharger of the same pollutant and should,
therefore, meet essentially the same requirements. A
variance provision will be included in the general
regulations allowing industrial sources who are users of a
POTW to apply for a variance from the numerical standard
when factors relating to the industrial user which are
fundamentally different from those considered in
establishing the standards justify significant differences
in discharge requirements.
Section 301 of the Act anticipates that pretreatment
standards for existing sources would be established and
compliance would be required before July 1, 1977, while
Section 307(b) specifies "a time for compliance not to
exceed three years from the date of promulgation11 of the
standard. In view of this conflict of statutory language
and the fact that the pretreatment standards are only now
being promulgated, the Agency believes that the compliance
deadline as set forth in Section 307 (b) should apply. The
time for compliance with the categorical pretreatment
standards will be within the shortest reasonable time, but
not later than three years from the effective date.
However, this does not preclude a Regional Administrator or
local or state authority from establishing a more
expeditious compliance date, on an individual basis, where
it is appropriate. Compliance with- the prohibited discharge
standards is required immediately upon the effective date of
these regulations, since these standards are essentially the
same as 40 CPR 128.131 and since the deadline for compliance
with 40 CFR 128.131 has passed.
Technical Basis for Pretreatment standards
The Act requires that pretreatment standards for both new
sources and existing sources be promulgated to prevent the
introduction of any pollutant into a POTW which would
interfere with the operation of such works or pass through
or otherwise be incompatible with such works. Such
standards would allow the maximum utilization of a POTW for
the treatment of industrial pollutants while preventing the
misuse of such works as a pass-through device. The
standards also would protect the aquatic environment from
discharges of inadequately treated or otherwise undesirable
materials.
13
-------
•The primary technical strategy for establishing pretreatment
standards consists of the following provisions: (1)
pretreatment standards should allow materials to be
discharged into a POTW when such materials are wastes which
a normal POTW is designed to treat; (2) pretreatment
standards should prevent the discharge of materials of such
nature and quantity, including slug discharges, that would
mechanically or hydraulically impede the proper functioning
of a POTW; (3) pretreatment standards should limit the
discharge of materials which, when released in substantial
concentrations or amounts, reduce the biological
effectiveness of the POTW or achievement of the POTW design
performance, but which are treated when released in small or
manageable amounts; and (4) the pretreatment standards
should require the removal, to the limits dictated by
technology, of other materials which would pass through—
untreated or inadequately treated— or otherwise be
incompatible with a normal type POTW.
GENERAL DESCRIPTION OF INDUSTRY H* CHEMICAL SUBCATB6ORY
The chemical subcategories included in this study vary in
terms of production, process, raw-material sources, reagents
used, and applicable pretreatment necessary for the
resultant waste streams. Therefore, they are discussed
separately throughout this document*
Aluminum Chloride
Industry Description. According to the Directory of
Chemical Producers '(Reference 1), there were 13'plants
producing aluminum chloride (A1C13) in 1974. Two of these
plants (operated by the same 'corporation) manufacture both
the hydrous and the anhydrous salts. The same source states
that 11 of the 13 plants represent a combined annual
capacity of 83,000 metric tons (92,000 short tons) of
aluminum chloride. This sum includes 49,000 metric tons
(54,000 short tons) of anhydrous product and 34,000 metric
tons (38,000 short tons) of hydrous product. The major use
for anhydrous aluminum chloride is as a catalyst in the
synthetic polymer and petrochemical industries. The hydrous
product is used as a flocculant and and as a pigment
fixative.
Manufacturinf Processes. Anhydrous aluminum chloride is
produced by injecting dry chlorine through a molten aluminum
charge at 660°C (1220°) (Reference 2). The basic equation
iss
2A1 + 3C12 » 2A1C13
14
-------
The chlorine (usually gaseous) is introduced below the
surface of the molten metal, and the product sublimes so
that it is easily condensed and collected. (See Figure 1),
Aluminum chloride condenses below 183°c (297°F),
Theoretically, the production of 1 metric ton (0.9 short
ton) of anhydrous AlCl.3 requires 182 kg (400 Ib) of aluminum
and 726 kg (1,600 Ib) of chlorine (Reference 2); however,
stoichiometric chlorination rates are difficult to obtain.
Scrap aluminum is frequently used as a raw material in
aluminum chloride manufacturing.
Condenser off gases are usually scrubbed with wet systems to
collect particulates and chlorine vapors. Caustic is
sometimes added to the scrubbing media to improve chlorine
collection and to relax high concentrations of hydrochloric
acid in the scrubber water.
An alternative process for producing anhydrous aluminum
chloride consists of reacting bauxite, coke, and chlorine at
a temperature of about 87Q°C (1600°F). The bauxite and coke
mixture is heated, and chlorine is blown into the furnace,
converting alumina, (aluminum oxide) to aluminum chloride.
The vapors are condensed to form a relatively pure product.
The reaction equation is:
A120.3 + 3C + 3C1J2 = 2A1C13 +3CO
The final anhydrous product may vary in color from yellow to
white to gray, depending upon the ratio of chlorine to
aluminum. An excess of chloride in the product produces a
yellow color, while an excess of aluminum results in a gray
color due to the presence of unreacted metal.
Hydrous aluminum chloride comprises a significant portion of
the total U.S. aluminum chloride production, and this
compound frequently serves as a precursor in the synthesis
of other chemicals. The hydrous product can be created by
reacting hydrated alumina or bauxite with hydrochloric acid.
The resultant solution is filtered to remove unreacted
residues or muds, and the product is containerized. Further
purification is sometimes required after filtration.
Emissions-control devices may be employed for control of
vapors generated during the reaction, and one plant reports
that the scrubber water is reintroduced to the reaction
chamber.
Figure 2 is a generalized process flow diagram of hydrous
aluminum chloride.
15
-------
Figure 1. FLOW DIAGRAM FOR TYPICAL PRODUCTION OF ANHYDROUS
ALUMINUM CHLORIDE
WATER
CAUSTIC
CHLORINE-
ALUMINUM •
FURNACE
•FUMES-
CONDENSER
JMI
OFF-GASES-
ALUMINUM
CHLORIDE
i
PACKAGING
SCRUBBER
SCRUBBER
WASTEWATER
TO SALES
-------
Figure 2, FLOW DIAGRAM FOR TYPICAL PRODUCTION OF HYDROUS
ALUMINUM CHLORIDE
MCI-
REACTOR
I
ALUMINUM
CHLORIDE
SOLUTION
— REACTION FUMIS
MUDS
OR
RESIDUES
i
FILTRATION
1
PURIFICATION
ALUMINUM
CHLORIDE
PRODUCT
WATER
t
SCRUBBER
t
SCRUBBER WASTEWATER
PACKAGING
TO SALES
17
-------
There were no POTW dischargers found in the aluminum
chloride subcategory. Of the seven plants where process-
water discharge status has been determined, three are direct
dischargers, while one plant has achieved zero discharge
status. The remaining three plants do not employ process
water.
Aluminum gulfate
Industry Description. The term "alum" has been loosely
applied, and a true alum is a double sulfate of aluminum or
chromium and a monovalent metal (or radical) (Reference 3).
However, in keeping with present terminology, "alum" in this
document refers only to aluminum sulfate (Al£ (SO4) 3) . The
most important commercial application for alum"" is as, a
flocculant (coagulant) in water treatment! thus, three large
U.S. cities are listed in the ranks of alum producers. The
second most prominent use is in the papermaking industry,
where iron-free alum is required for the sizing of paper.
The Directory of Chemical Producers (Reference 1) lists 82
plants as producing alum in 1974. Of these, fifteen are
known to make iron-free grade alum. The total annual
production of alum exceeds 1.1 million metric tons (1.2
million short tons).
Manufacturing Processes, Aluminum sulfate is produced by
the reaction of concentrated sulfuric acid with bauxite,
clay, and other compounds containing aluminum oxide. iron-
free, alum is often produced by utilizing relatively pure
hydrated alumina (aluminum oxide) as a source of aluminum.
The general equation of the reaction is (Reference 4)z
&12Q3 •• 3H2O + 3H2SO4 ~ A12 (SO4) 3 * 6H.2O
In this typically batch operation, the aluminum-bearing
material and acid are reacted in a digester, where heat is
usually added to promote reactivity. The whole mixture
(water and solids) is fed to a settling tank, where the
insolubles (muds) are removed. Some muds are washed to
recover entrained aluminum sulfate solution. The overflow
from the settling tank is further purified by clarification
or filtration. Other steps taken to remove impurities
include addition of materials such as aluminum powder (for
iron reduction), activated carbon (for color control), and
polyelectrolyte (to improve settling). The resultant
solution can be sold or routed to an evaporation stage for
alum-crystal production. A generalized flow diagram for
alum production is displayed in Figure 3.
18
-------
Figure 3. FLOW DIAGRAM FOR TYPICAL PRODUCTION OF ALUMINUM
SULFATE. • •
BAUXITE^.
SULFURIC ACID-I*"
WATER -I
ALUMINUM
PACKAGING
SOLID
ALUMINUM
SULFATE
PRODUCT
TO
SALiS
R ESI OUiS
-------
There are many modifications to the generalized flow diagram
in practice today. One municipal alum producer digests
bauxite with sulfuric acid and employs the resultant slurry
as a flocculant to improve turbidity characteristics of city
drinking water. (Clearly* there are no settling or
purification steps which follow digestion.) Many plants
impound the waste residues (muds) and associated .transport
water for recycle after settling. The acidic water is fed
back to the digester. Other plants discharge residue
transport water, residue wash water, and filtrate generated
by purification steps. One plant uses a wet scrubber to
collect dusts from various pickup points (presumably,
bauxite crushing and grinding) throughout the plant and
shunts a portion of the scrubber recycle stream to the alum
digesters. The same plant diverts a portion of its mud wash
water to settling ponds and, eventually, to discharge.
There are no known POTW dischargers in this subcategory, and
the discharge status of most plants is unknown. At the
plants evaluated, total recycle is common practice at alum
manufacturing plants, and dischargers are presumably a
minority in the industry.
Calcium carbide
Industry Description. Production of calcium carbide (CaC2)
falls under two categories: the Inorganic Chemicals
Manufacturing category and the Ferroalloy Manufacturing
category. Calcium carbide production is categorized and
regulated according to the type of furnace used. All
production of calcium carbide from covered furnaces is in
the Ferroalloy Manufacturing category (40C.F.R. 424,
Subparts D&l), Open (uncovered) furnaces is included in the
Inorganic Chemicals Manufacturing category.
Three plants using uncovered furnaces were studied for this
report. The three plants produce an approximate total of
87,000 metric tons (96,000 short tons) annually, which
accounts for nearly 25% of the total annual (all furnace
types) calcium carbide production.
Manufacturing Process. Calcium carbide is produced by
reacting calciumoxide (lime or limestone) with carbon (in
the form of coke, petroleum coke, or anthracite) at 2000 to
2200°C (3630 to 3990°F) in either an electric or an arc
furnace. The general equation for the reaction is:
2CaO + ftC + Heat = 2CaC2 * 02
20
-------
Figure 1 is a basic flow diagram of calcium carbide
production.
The raw materials are crushed and dried before addition to
the furnace. The furnace is cooled with a noncontact
system. The product is air-cooled, crushed, screened, and
packaged or stored, since the production process is dry,
the only discharges are dusts and furnace off-gases.
No calcium carbide plant contacted discharges to a POTW.
Calcium Chloride
Industry Description. Calcium chloride (CaclZ) is produced
by twelve plants in the United States at present, and seven
of these plants are located in Michigan, California, and
Washington, The remaining plants are well dispersed
throughout the nation. The Directory of Chemical Producers
(Reference 1) states that nine of the plants represent a
combined annual capacity of 1.029 million metric tons (1.135
million short tons), with a significant portion of the total
attributable to production from natural sources in Michigan.
The major uses for calcium chloride are for road deicing,
dust control, and concrete treatment (Reference 2).
Manufacturing Processes.' Classicly, calcium chloride has
been extracted as a joint product from natural salt brines,
and as a byproduct of soda ash (sodium carbonate)
manufacture via the solvay process. Both methods are
similar after the raw brines have been purified: the
solutions containing calcium chloride are concentrated and
crystallized. However, other, less complex processes, such
as reaction of limestone and hydrochloric acid are practiced
to produce smaller quantities of the salt. It is these
smaller operations which are likely to be located in an
urban environment where POTW discharge is feasible.
The brine recovery process is practiced in Michigan by two
large operations, and the process flow diagram for one plant
appears in Figure 5. Briefly, the salts are solution-mined,
and the resulting brines are separated, iodine, bromine, and
magnesium compounds being routed to other recovery circuits.
The remaining solution is then partly evaporated to remove
sodium chloride by precipitation. The sodium chloride
removal involves a large degree of brine recycling. The
brine is further purified by addition of other reagents to
remove sodium, potassium, and magnesium salts by
precipitation and further evaporation. The purified
concentrate is then evaporated to dryness to recover calcium
chloride. The product may be sold as a hydrated solid or
diverted to a flaker to form hydrated flakes. Anhydrous
21
-------
Figure 4. FLOW DIAGRAM OF STANDARD PROCESS FOR PRODUCTION OF
CALCIUM CARBIDE
IN3
COKE
COAL-
CRUSHER
DRYER
HOT
AIR
AIR-SWEPT
PULVERIZER
fp»
I
i
[*-
KILN
LIMESTONE-
CRUSHER
COOLER
AIR
L
QASViNT
I
GAS
SCRUBBER
CARBIDE
FURNACE
f
WASTE
PRODUCT
COOLER
I
CRUSHER
NONCONTACT
COOLING
PACKAGING
T
TO SALES
-------
Figure B. FLOW DIAGRAM FOR PRODUCTION OF CALCIUM CHLORIDE FROM
NATURAL BRINE (PLANT 19404}
BRINE
FROM.
WELL
SEPARATOR
I
IODIDES, BROMIDES, AND
MAGNESIUM TO OTHER PROCESSES
INVENTORV
COOLING"
WATER .
I
EVAPORATOR
WASTE
««- STEAM
•»~CONDENSATE
•COMPENSATE
SODIUM CHLORIDE
SEPARATOR
SODIUM CHLORIDt
DISSOLVER
TO
SALES'
PACKAGING
38%
CALCIUM
r*CHLORIDE •
PRODUCT
CALCIUM CHLORIDE
PROCESS
WATER
VENT TO.
EXHAUST
i
PURIFIER
I
TOCHLOR-ALKALI
COOLING
.WATER
SCRUBBER
WASTE -*-
i.
EVAPORATOR
I
I-STEAM
>-CONDENSATE
FLAKER AND DRYER
•COOLING
-WATER
ANHYDROUS PRODUCT
i
PACKAGING
TO SALES
SOURCE: REFERENCES
23
-------
product may be formed by heating the hydrated product to
form fused calcium chloride, which is about 95% pure. The
coded material is crushed and screened for sale.
The Solvay (byproduct) calcium chloride process begins with
a clarified liquor from the clarifiers. The relatively pure
liquor contains calcium and sodium chlorides and a small
amount of calcium sulfate. The liquor is introduced into
triple-effect evaporators, where most of the sodium chloride
(plus some calcium sulfate) crystallizes during the first
effect. Subsequent evaporation effects occur until the
specific gravity reaches a point where nearly all the sodium
chloride has been crystallized and settled. The purified
liquor is then thermally concentrated until it becomes a
molten mass. The product can be cooled directly to form a
hydrated solid calcium chloride or converted to anhydrous
product.
A third process for calcium chloride manufacture consists of
reacting limestone (calcium carbonate) with hydrochloric
acid to form a solution containing about 36% calcium
chloride. Solid waste from the process consists of
insolubles left as residues from limestone digestion. A
similar, process involves reaction of calcium carbonate (in
the presence of hydrogen peroxide and calcium oxide) with
hydrochloric acid to form a pure solution, which is
subsequently concentrated and dried to form a solid product.
A generalized flow diagram for this type of process is shown
in Figure 6.
An additional process for synthesizing high-purity solid
calcium chloride is practiced at the only known POTW
discharger in the industry. Two salt solutions are first
filtered with bone coal and then reacted. The resultant
solution is then boiled to yield a precipitate which is
dehydrated in a horizontal dryer. A scrubber which collects
emissions generated during the boildown step generates a
waste water which contains hydrochloric acid. A flow
diagram for this process is shown in Figure 7.
The only POTW discharger in the calcium chloride subcategory
uses a municipal treatment system practicing primary
settling and resultant sludge incineration. The average
daily flow to the POTW is 0.45 million cubic meters (120
million gallons)r and 40% of the total influent is
industrial in origin.
Copper (Cupric) Sulfate
Industry Description. The six copper sulfate plants studied
account for approximately 70% of the total U.S. production
24
-------
Figure 6. GENERALIZED FLOW DIAGRAM FOR PRODUCTION OF CALCIUM
CHLORIDi FROM CALCIUM CARBONATE
HYDROCHLORIC
ACID
LIMESTONE
on
CALCIUM
CARBONATE
CATALYSTS!
ft
REACTOR
INSOLUBLES TO WAST!
DILUTE CALCIUM
CHLORIDE
SOLUTION
PACKAGING
36% CALCIUM
"CHLORIDE PRODUCT
TO SALES
i
FILTER
SOLIDS TO WASTE
PURIFIED
CALCIUM CHLORIDE
SOLUTION
ADDITIONAL
REAGENTS
1
CONCENTRATOR
CONCENTRATED CALCIUM
CHLORIDE PRODUCT
PACKAGING
CONCENTRATED CALCtUM_
CHLORIDi SOLUTION
TO SALES
DRYER
SOLID CALCIUM
CHLORIDE PRODUCT
i
PACKAGING
TO SALES
25
-------
Figure 7, FLOW DIAGRAM FOR PRODUCTION OF HIGH-PURITY CALCIUM
CHLORIDE (PLANT 19406)
REACTANT REACTANT
SOLUTION SOLUTION
i i
1 FILTER | 1 FILTER ]
i
| REACTOR
SOLUTION
BOILDOWN
1
|
1— EMISSIONS
*-
SCRUBBER |
SOLID f
SCRUBBER WASTE
DRYER
HIGH-PURITY CaCI2
PACKAGING
TO SALES
26
-------
of copper sulfate. The average yearly production of the six
plants combined is 23,400 metric tons (25,800 short tons).
The markets for copper (cuprie) sulfate are in wood
preservation (when mixed with sodium chromate) ,t as trace
components for copper-deficient soils, and for water
treatment (use as an algicide).
Manufacturing Prc-cejss. Copper (cupric) sulfate is produced
by the action of sulfuric acid on copper. Normally,
production of copper sulfate is a sideline with copper
refiners. Copper shot, copper scrap, or electrolyte
solutions containing copper are the raw materials used in
manufacture. Either concentrated or dilute sulfuric acid
may be used.
All of the plants studied produce copper sulfate
pentahydrate. The process reaction is:
2CU 4 O2 + 2H2SO4, + 5H2O = 2CuSC)4«5H2O * 2E2O
The resulting solution is sold in its entirety by four of
the six plants studied. The production of the four plants
is approximately 2,200 metric tons (2,420 short tons) per
year. The other two plants evaporate, crystallize, and
centrifuge the solution to obtain copper sulfate
pentahydrate crystals. The crystals are dried, screened,
and packaged. Figure 8 is a basic process diagram for
copper sulfate crystal production.
All of the plants studied have minimal waste flow. The high
value of copper is an incentive to recycle or recover most
process wastes and to minimize the metal content in the
water effluent. Hot one of the copper sulfate plants
studied discharges to a POTW.
Plants 19501, 19502, 19503, and 19504 produce copper sulfate
solution containing approximately thirty percent copper
sulfate pentahydrate. Figure 9 is a diagram of the process
used at each plant to produce copper sulfate solution.
Water use in the process is slight as tabulated below. The
resulting solution is sold in its entirety; consequently,
there is no waste water effluent.
Plant Code Production Water^tJse
, kg/day (Ib/day) I/day (gp<3)
19501 181 (400) 64 (17)
19502 635 (1400) 227 (60)
19503 680 (1500) 246 (65)
19504 4,536 (10,000) 15,142 (4,000)
27
-------
Figyre 8. FLOW DIAGRAM OF STANDARD PROCESS FOR PRODUCTION OF
CUPRIC SULFATE
COPPER ~a»»
SULFURICACID-*-
AIR
WATER
REACTOR
SETTLING
f
t
SLUDGE
EVAPORATION
MOTHER LIQUOR
CRYSTALLIZATION
CENTRIFUGATION
co-
DRYING
SCREENING,
PACKAGING
t
PACKAGING
PRODUCT
TO SALES
-------
Figure 9. FLOW DIAGRAM OF PROCESS FOR MANUFACTURE OF CUPRJC
SULFATE SOLUTION
SCRAP
COPPER {WIRE, ETC.)
SULFURICACID
WATER
ITER
•ti :[
REACTOR
PACKAGING
PACKAGED SOLUTION
TO SALES
29
-------
Plant 19505 produces copper sulfate crystal using crude
copper shot and electrolyte solution from its refinery aa
the sources of copper and sulfurie acid. The only waste
water flow from this plant results from noncontact cooling
water, noncontaet steam condensate, and treated washdown
water. Treatment for the washdown water includes
neutralization* settling, and filtration.
Plant 19506 uses copper shot as the raw material in crystal
production, since all of the mother liquors and wash waters
are recycled at plant 19506, only the water from the
barometric condenser on the vacuum crystallizer is
discharged.
Iron (Ferric) chloride
Industry Descrigtipn.• There are 18 plants in .the United
states producing . various grades of ferric chloride (FeC13)
(including specialty and photo grades) . Total U.S.
production in 1974 was 138,000 metric tons (152,000 short
tons) (Reference. 1). Of the 18 ferric chloride producers,
two discharge process waste water - to a POTW. These two
indirect dischargers account for only 71 of the total 0»S.
production of ferric chloride. Average production of the
two POTW dischargers is 4,500 metric tons/year (5,000 short
tons/year). This in in contrast to several of the direct
dischargers, whose annual production of ferric chloride
range from 18,000 to 27,000 metric tons (20,000 to 30,000
short tons). However, it is well within the range of all
ferric chloride producers (Reference 1). •
Manufacturing Process,. Commercial solutions of ferric
chloride are produced from iron and steel pickling liquors,
which contain ferrous chloride (FeCl2) and hydrochloric
acid. The steel pickling liquors are preheated with , steam
and then reacted with iron, chlorine, additional
hydrochloric acid, and water to produce the desired
solution. (A process flow diagram is- presented in Figure
10). The overall reactions involved are:
Fe * 2HC1 ' = FeC12 * H2
2FeCl2 + C1J2 - 2FeC13
Crystallization produces a hexahydrate (FeCi3_.6M2O) , which
is hygroscopic and very soluble in water. "~ ~*
Solutions of ferric chloride are used as a copper etchant in
photoengraving, in textile dyes, for the chlorination of
copper and silver ores, for pharamaceuticals production, as
30
-------
Figure 10, FLOW DIAGRAM FOR TYPICAL PRODUCTION OF FERRiC CHLORIDE
WATER
IRON "-
PICKLE LIQUOR—»
JL
HYDROCHLORIC
"ACID
-CHLORINE
REACTOR
FERRiC
CHLQRIPE"
SOLUTION
SOLID FERRiC CHLORIDE
I
PACKAGING
TO
SALES
31
-------
an oxidizing agent in chemical synthesis, and for water
purification.
Production of ferric chloride by passing chlorine gas over
iron at red heat or by oxidizing anhydrous ferrous chloride
with chlorine is not included in this study because this
process accounts for only a small part of the total
production.
Lead Monoxide
Industry Description. The lead monoxide (PbQ, or litharge)
subcategory contains about 16 plants, none of which is known
to discharge to publicly owned treatment works. Of the 16
plants, 11 discharge directly to surface waters or have no
process waste discharge. The discharge status of the
remaining five plants is unknown. There is no significant
locational pattern, with plants located in 10 states from
California to New York.
Manufacturj ng Processes. Although there are four
commercially important processes for manufacturing litharge,
all involve primarily the air oxidation of metallic lead;
rapid cooling of the product; and, in three of the four
cases, milling of the resultant coarse particles. Process
diagrams are shown in Figure 11. Descriptions of the
processes follow.
In Process lf lead is melted in the presence of air
(usually, on a flat hearth). During this low heating (never
over a full red heat), a scum of lead suboxide forms. This
is raked or blown aside so that more may be exposed for
oxidation. The partially oxidized lead is milled to a
powder and charged to a reverberatory furnace, where it is
heated to about 600°c (1112°P) to complete the oxidation.
Most litharge for storage-battery plates is made by this
process.
In Process 2, pig lead is melted and stirred in the presence
of air, in either a reverberatory furnace or rotary kiln, to
form litharge directly.
In Process 3, lead or a lead/silver alloy is melted in a
eupellation furnace at 1,000°C (1832°F). As air is passed
through the furnace molten litharge is formed and is allowed
to overflow into a receiver where it cools and solidifies.
The solidified oxide is broken up and milled to desired
size.
In Process U, molten lead at 500°C (932°P) is atomized into
an oxidizing flame in a specially built furnace where it
32
-------
Figure 11. FLOW DIAGRAMS OF FOUR ALTERNATIVE PROCESSES FOR PRODUCTION
OF LEAD MONOXIDE USING AIR OXIDATION OF LEAD
CO
mALLY OXIDIZED ^
OWDERED LEAD
r
Al
PIG LEAD
1
Al
MOLTEN LEAD
1
A
MOLTEN LEAD ]
i
R
•^
R
^h*"
r
R
*•
i
REVERBERATORY
FURNACE
ROTARY
FURNACE
CUPELLING
FURNACE
ATOMIZER
i
t
•»•
»^
•*-
COOLER
-
COLLECTOR
(a) PROCESS 1
COOLER
*•
COLLECTOR
•*-
•*-
MILL
LEAD
- MONOXIDE — *-
(POWDERED)
PRODUCT
PACKAGING
MILL
LEAD
- MONOXIDE -*-
(POWDERED)
PRODUCT
PACKAGING
(b) PROCESS 2
COOLER
•*-
COLLECTOR
(c) PROCESS 3
:URNACE
•*-
COOLER
(d) PROCESS 4
•*•
•»-
MILL
LEAD
- MONOXIDE — »•
(POWDERED)
PRODUCT
PACKAGING
_fcr._ TO
SALES
*- TO
TO
"^"SALES
MONOXIDE
COLLECTOR -("FUMED" OR*1
"SUBLIMED'1
PRODUCT
PACKAGING
-k~ TO
SALES
AIR
SOURCE: REFERENCE 2
-------
burns to form very finely divided particles (0.25 to .0.5
micrometer) of "sublimed" litharge. The fine powder is
cooled rapidly and collected. No other processing is
necessary.
In all cases, the product must be cooled quickly to less
than 300°C (572°F) to avoid the formation of red lead
(PbKMJ) . The products from the first three mentioned
processes must be milled to suitable size (1.5 to 8
micrometers).
Most of the plants in this subcategory do not use water in
the chemical manufacturing process. The major water-using
operations are noncontact cooling and washdown of dusts from
plant surfaces. For this reason, only plants practicing
washdown of dusts will have any significant process waste
water discharge. All lead oxide plants which utilize
compressed air in the manufacturing process will have a
process waste water discharge from compressor "blowdown,tr
although the quantity of this waste water will be minor.
Plants which do not employ water cooled compressors and
utilize good housekeeping procedures in conjunction with the
dry vacuuming of dusts will have no process waste water to
discharge.
Raw materials used in the process consist of powdered pig
lead (partially oxidized lead) and air. No other chemical
reagents are necessary. On a basis of 1 metric ton (1.1025
short tons) of litharge product, 948 kg (2090 Ib) of pig
lead is consumed. The amount of air required is variable.
Theoretically, 50.3 cubic meters (1,775 cubic feet) of air
is required per metric ton of litharge at standard
temperature and pressure (Reference 2).
None of the 11 lead monoxide producing plants contacted in
this subcategory were identified as discharging process
waste waters to a POTW.
Nickel Sulfate
Industry Description- There are 12 known plants in the
United States producing solutions of nickel sulfate (NiSO4J
and nickel sulfate hexahydrate crystals. Total U.S.
production in 1972 was 13,400 metric tons (14,800 short
tons). Production at individual plants ranges from 90
metric tons (100 short tons) per year to 6,800 metric tons
(7,600 short tons) per year (Reference 6).
Of the 12 nickel sulfate producers, only three discharge
process waste water to a POTW. These three indirect
-------
dischargers account for approximately 30% of the total 0. S.
production of nickel sulfate.
Mania fact uring Processes. The raw materials for the
production of nickel sulfate include metallic nickel, nickel
oxide, spent nickel-plating solutions, and spent nickel
catalysts. The processes employed vary, depending in the
raw materials. However, the basic process involves reacting
the raw material with sulfuric acid to produce a nickel
sulfate solution. The reaction with nickel oxide as feed
is: .
NiO + HJ2S04, = NiSO§ + H2O
The resultant solution is filtered to remove participates
and may be treated with sulfides, lime, sulfuric acid, etc.,
when necessary to remove metallic impurities. The purified
nickel sulfate solution is then either sold, used in-plant,
or crystallized to a hexahydrate for sale. A basic process
flow diagram is presented in Figure 12.
Nickel sulphate is used in electroplating baths, for the
production of other nickel compounds, as a mordant in dyeing
and printing fabrics, and in blackening zinc and brass.
Mtrogen a^nd Oxygen
- Industry Description. The nitrogen (N2J and oxygen (O2)
production subcategory of the inorganic chemicals industry
encompasses a vast number of processing plants which
manufacture gaseous and liquid products via air separation.
Current survey figures indicate that the industry consists
of approximately 193 plants, representing some 25 companies
(Reference 1), and is capable of producing nitrogen and
oxygen in annual quantities exceeding 22 million metric tons
(24 million short tons) . A breakdown of this production
data reveals that approximately 7.3 million metric tons (8.1
million short tons) of nitrogen and 15.3 million metric tons
(16.9 million short tons) of oxygen are produced annually in
the United states (Reference 7) ,
Production capacities of air-separation plants range from 11
to 9,100 metric tons (12 to 10,000 short tons) of chemical
per day, with the average plant producing approximately 535
metric tons (590 short tons) of combined product daily
(Reference 1). Note that production figures quoted for air-
separation plants frequently reflect total nitrogen and
oxygen produced, rather than individual product data. In
discussing this .subcategory, combined product figures are
used unless some significant process distinction exists in a
35
-------
Figure 12, FLOW PROGRAM FOR TYPICAL PRODUCTION OF NICKEL SULFATE
NICKEL-8EAHINO
suuume
PURIFICATION
CHfMICALS
NICKEL
SULFATt -*-
»LUtlOH
fltTlS
CB^STALtlJER
1
ORVfH
36
-------
particular plant which precludes this method of utilizing
production data.
location of air-separation plants throughout the country is
frequently dependent on the desired application of the
chemical being produced. A number of these air-separation
plants are known to be on-site locations providing high-
purity product for use in specific industrial processes.
Common examples are the plants which manufacture high-grade
oxygen for use in the steel industry and those which produce
pure nitrogen for textile mills. These on-site air-
separation plants are responsible for producing a
significant portion of the total nitrogen and oxygen manu-
factured by the industry. Smaller plants may be located
adjacent to an industrial complex and, although not on-site,
may opt to supply a direct line for gas transportation to
the industry. In addition to directly servicing the
industries, many of these plants also manufacture gaseous
products for commercial distribution.
Manufacturing Processes,, . The standard industrial process
utilized in manufacturing nitrogen and oxygen is air
separation. The fundamental technology for this process was
developed in the early part of this century and is one of
the oldest chemical processes in existence.
The basic process is as follows: Filtered atmospheric air
is compressed, purified by removing its carbon dioxide and
water-vapor components, cooled by a series of heat
exchangers, and fractionally distilled into the desired
products in a double-column rectifier. Various
technological modifications of the fundamental process have
resulted in minor distinctions, as can be seen in the
process flow diagrams which follow. Figure 13 represents a
typical high-pressure system with reciprocating-type air
compressors, caustic scrubber, and activated-alumina air
dryer. This system is somewhat older chronologically than
the one shown in Figure 14. The latter is a low-pressure
cycle employing centrifugal compressors and a series of
reversing exchangers which serve to both cool and purify the
air. The function of the exchangers is analogous to that of
the caustic scrubber and activated alumina of the older
system—i.e., they accomplish both carbon dioxide removal
and evaporation of excess water vapor. The argon-recovery
step in Figure 13 is optional in the air-separation process
and is employed in accordance with the needs of the
individual plant.
For those plants which are producing nitrogen only, the
distinguishing design modification is in the rectifier
column. A single low-pressure column is substituted for the
37
-------
Figure 13. FLOW DIAGRAM OF TYPICAL HIGH-PRESSURE AIR-SEPARATION PROCESS
(MODIFIED CLAUDE CYCLE) FOR PRODUCTION OF NITROGEN AND OXYGEN
<*»
03
ATMOSPHERIC
AIR
i
Am HLTIB
1
RECIPROCATING
COMPRESSOR
WATER
COOLER
CAUSTIC
SCRUBBER
1
RECIPROCATING
COMPRESSOR
1
WATER
COOLER
WASTi TO
ATMOSPHERE
(GASEOUS
NITROGEN!
DOUBLE-COLUMN
RECTIFIER
-H
-CRUDE ARGON-
TO SALES
-------
AIR
Figure 14, FLOW DIAGRAM OF LOW-PRESSURE AIR-SEPARATION PROCESS
(MODIFIED LINDE-FRANKL CYCLE) USED IN TYPICAL PRODUCTION
OF NITROGEN AND OXYGEN
REVERSING
HEAT
(EXCHANGER
OXYGEN
(GAS)
SOURCE: REFERENCE 2
-------
double*column rectifier, and the oxygen rich mixture formed
in the column is wasted rather than recovered.
Commercial oxygen utilization, particulary in industrial
applications has undergone considerable growth in recent
years. Demand for the chemical (notably, in the steel
industry) has increased significantly due to the development
of new processes which are highly oxygen consumptive.
In the chemical industry, manufacture of acetylene and
ammonia accounts for a significant portion of the total
oxygen utilized by this industry. Planned new processes in
the cement and copper refining industries, as well as
continued use in missile and rocket development, should
sustain the rate of growth in oxygen manufacturing.
High-purity nitrogen gas has several industrial
applications, the most notable being in the textile
industry, where it is used in the production of nylon and
other synthetics. Secondary uses include the manufacture of
plate glass and the preservation of certain processed foods.
Of the 193 air-separation plants identified in the industry,
the majority discharge their process waste waters directly
to surface streams. However, according to information
provided by the industry, at least 33 are known to be
discharging to POTWs.
Data compiled on these POTWs indicate that 26 percent of
those receiving industrial process waters are primary
treatment facilities, with flows ranging from 1,500 to
41,600 cubic meters/day (0.4 to 11.0 mgdj. The remaining
POTWs are secondary treatment facilities, with flows ranging
from 4,900 to 3,400,000 cubic meters/day (1.3 to 900 mgd).
The average amount of industrial flow handled by a primary
plant is 13 percent of the total daily flow, with secondary
plants handling an average industrial flow of 20 percent.
There appears to be no particular distinction between the
characteristics of process waste waters discharged directly
to the surface as compared to those discharged to POTWs.
Potassium Pichrornate . '
Industry Description. The single plant known to manufacture
potassium dichromate (Kj2Cr2Q2) does not presently discharge
process-associated waste water to a POTW.
Annual domestic production for potassium dichromate is
estimated to be 4,000 metric tons (4,400 short tons)
(Reference 4). This chemical finds use as an oxidizing
40
-------
agent (chemicals, dyes, intermediates, and as an analytical
reagent) . It is also used in brass pickling compositions;
electroplating; pyrotechnics; explosives; safety matches;
textiles; dyeing and printing; glass; chrome glues and
adhesives; chrome tanning leather; wood stains; poison fly
paper; process engraving and lithography; photography;
pharmaceutical preparations; synthetic perfumes; chrome alum
manufacture; pigments; alloys; and ceramic products.
Manufacturing Process. Only one U.S. plant is known to
manufacture potassium dichromate. The production process
employed at this plant involves the reaction of a sodium
dichromate dihydrate solution with potassium chloride
according to:
Na2Cr2O7.2H20 + 2KC1 = IQCrO? + 2NaCl + 2H2O
From a hot solution of these salts, potassium dichromate is
crystallized by vacuum cooling. (Sodium chloride is
crystallized by subsequent evaporation.) The potassium
dichromate crystals are separated from the mother liquor by
centrifugation, then dried and sized prior to packaging.
(The sodium chloride solids collected by evaporation of the
mother liquor are discarded as solid waste.) Residual
mother liquor is recycled to the initial reaction tank.
This process is presented schematically in Figure 15.
Potassium Iodide
Industry Description. The total U.S. production of
potassium iodide (KI) is accounted for by four plants.
Geographically these plants are widely distributed, two
being located on the East Coast, one on the West Coast, and
the fourth" in the Mississippi Valley Region. Annual
domestic production for 1972 amounted to 998 metric tons
(1,100 short tons) (Reference 6).
Manufacturing Processes, At each of the four plants which
presently comprise this industry subcategory, the
manufacturing process employed yields potassium iodide in
batch quantities.* The number of batches produced per year
at any one plant varies with demand and over at period of
years can change greatly. Plants engaged in the manufacture
of potassium iodide are typically also engaged in the
manufacture of a multitude of other chemical products, both
inorganic and organic. At one of these plants, as many as
600 different chemicals are produced in the period of a
year.
-------
Figure 15. FLOW DIAGRAM FOR TYPICAL PRODUCTION OF POTASSIUM
DICHROMATE
SODIUM
DICHROMATE
LI0UOB
1 POTASSIUM
j CHLORIDE
f f
REACTION M
j/atK *" T*
i
• •' M ct r i,Ltu uuuui
RIVER COOLING WATER
i i
I T
BAROMFTRIC
*>K VACUUM '
» * „ _
FILTER
WASTE
1 SOLID)
r
L-J
PRODUCT
:ENTRIPUGE
I
POTASSIUM
DICHROMATE
1
SALT
CONCEHTRATOR
(STEA1*
HEATEOI
DRYER
HEATEOf
t
BUY
DUST
COLLECTOR
SODIUM
CEWTBIFUeE
SOLID
WASTE
SIZE*
PRODUCT
TO
SALES
SOURCE: REFERENCE 4
-------
The production processes employed at two of the domestic
plants are similar, essentially involving the reaction of
iodine with potassium hydroxide in solution according to:
312 + 6KOH * SKI * KIO.3 + 3H2O
About 801 of the iodate crystallizes from the reaction
mixture and is further processed as a byproduct. Of the
remainder, 90% is decomposed to iodide during evaporation,
fusion, and heating of the iodide solution in a gas-fired
furnace:
2KI03. = 2KI * 302
The fused potassium iodide is redissolved in distilled water
and treated with carbon dioxide for pH adjustment and small
amounts of barium carbonate, potassium carbonate, hydrogen
sulfide, and iron iodide to precipitate sulfate and heavy-
metal impurities. Following this purification step, the
potassium iodide is recrystallized from solution in a series
of steam-heated crystallizers, collected by centrifugation,
dried, screened, and packaged for sale. A schematic repre-
sentation of this process is presented in Figure 16.
An alternate method of production, which avoids the
formation of the iodate, is referred to as the iron and
carbonate process. This process, as practiced by one U.S.
plant, is presented schematically in Figure 17. Basically,
this process involves the reaction of iron powder with
iodine in solution. The compound formed,
ferrosoferriciodide (Fe3_I8.. 16H2O), is then reacted with a
slight excess of potassium carbonate solution:
F63I8-16H2O + HK2CQ3 - 8KI + HCO2 «• Fe3Q4 * 16B20
A small amount of barium hydroxide and potassium sulfide is
also added during this step to precipitate trace sulfate and
heavy-metal impurities. Waste solids are removed by
filtration. The potassium iodide solution is concentrated
by evaporation and subsequently cooled to effect crystal-
lization. The slurry leaving the crystallizers is
centrifuged to separate the residual mother liquor and
potassium iodide crystals. The crystals are subsequently
dried, sifted, and packaged for sale, while the mother
liquor is recycled to the evaporator.
The manufacturing process employed at the fourth domestic
plant (Figure 18) is similar to the iodine/potassium
hydroxide process. At this plant, iodine and potassium
hydroxide are also the major reactants. However, in this
process, iron powder is added as a reaction catalyst. The
-------
1«. PLOW DIAGRAM OF 1ODIN1/POTASS1UM HYDROXIDE PROCESS FOR
PRODUCTION OF POTASSIUM IODINI AND BYPRODUCT POTASSIUM
IOOATE
IODINE.
POTASSIUM HVOROXIDf •
DISTILLED WATER-
WATER ^
OXY6BW-*-
REDISSOLVINQ WATER -f»*
BARIUM CARBONATED (FOR pH
POTASSIUMCARBOMATE ( ADJUSTMENT
HYDROGENSULFIDE )
AND
FERROUS IODINE f IMPURITY
CARBON DIOXIDE! PRECIPITATION)
SOLID WASTE •
pH ADJUSTMENT-,
SOLID WASTE-
STEAM
CONDENSATI
(RECYCLED)
POTASSIUM
IODATE
COPBODUCT
• SOLID WASTE
BRINE COOLING
SYSTEM
•>_ TO SALIS
SOURCE: REFERENCE 0
44
-------
Figure 17. FLOW DIAGRAM OF IRON CARBONATE PROCESS FOR PRODUCTION OF
POTASSIUM IODIDE
CONDENSATE BARIUM
WATfR """ ' HVUROXIDfc
POTASSIUM POTASSIUM
CARBONATE SULFIDE
t " " 1'
WON POWDER — p- 1— —
IODINE — »- REACTOR REACTOR _ '^ CIITF
MUNICIPAL ^,
WATER ~~ 1
" " t i
4*.
tn
,OD NE MISC. SUMP LIQUORS
(TRACE)
SO
IRONCA
ANDC
WASTE P
WATER VAPOR COOl
(CONDENSATE WAI
TO REACTOR)
1 ' 1
ING
ER
R ™^- EVAPORATOR -*• CRYSTALLI
T__MOTHER J
LIQUOR
1 , !
.ID NONCONTA
FIBONATE WATER 1
JTHER
RODUCTS
'1 t
SIFTER
POTASSIUM
IODIDE PRODUC1
\ 1
CT COOLING •
TO SEWER PACKAGING
TO SALES
-------
Figure 18. FLOW DIAGRAM OF IRON-CATALYST PROCESS FOR PRODUCTION
OF POTASSIUM IODIDE
WATER
IODINE • — .-. - 4S* POTASSIUM
1 , , , . 1 HYDROXIDE
DEroNIZf-n fcj
WATER 1
SLURRY
*
-
** ^TAMK"* ~ — SUPERNATANT -»•
i
WASTE SLURRY
TO SOLID-WASTE
LAND FILL
POTASSIUM
ip MOTHER LJOUOR "
1
\ /
\ /
\ /
FILTER
V
CRYSTALLIZER
1
PPWTRf FUrrc _^^. MOTHER fc
CENTRIFUGE -«. L,QUOR *-»
1
POTASSIUM IODIDE
CRYSTALS
1
PACKAGING
T
TO SALES
-------
ferric hydroxide and iodate formed during the reaction are
discarded as waste solids. Any residual iodate in the
supernatant is subsequently reduced to iodide by the
addition of a small amount of potassium thiosulfate. This
process is also unique to the extent that no water is used
for cooling during crystallization. At this plant,
crystallization is effected simply by pouring the slurry
produced by evaporation into nickel pans and allowing
sufficient time for the crystals to grow.
Two of the four plants engaged in the manufacture of
potassium iodide presently discharge their production-
related waste waters to POTWs. Both POTWs provide only
primary treatment; however, at one, secondary treatment is
in the design stage. One of these POTWs presently treats
135,300 cubic meters/day (115 mgd)r 10 percent of which is
industrial waste water. The other POTW treats 984,000 cubic
meters per day (260 mgd) *
Potassium iodide .is used in photographic emulsions, in
animal and poultry feeds (to the extent of 10 to 30 mg/kg
(ppm)), in table salt, and in analytical chemistry. It also
has a number of medical uses.
Silver Nitrate
Industry Description. There are three significant plants in
the United states producing silver nitrate (AgHO3) . Total
U.S. production of silver nitrate in 1971 was 3,100 metric
tons (3,100 short tons).
Manufactujring Process. Silver nitrate is produced ' by
dissolving purified silver (up to 99.97% pure) in medium-
strength nitric acid. The resultant silver nitrate solution
is evaporated to a concentration of 85% and is then
crystallized by cooling; the crystals are separated by
centrifugation. The silver nitrate crystals are then
purified by redissolution in hot distilled water,
recrystallization, and recentrifugation (Reference 5). A
simplified process flow diagram is presented in Figure 19.
The basic reaction is:
2Ag + 2HNO3 * 2AgNO3 + m
Silver nitrate is the starting material for the preparation
of many other silver compounds. Most silver nitrate is used
in the photographic industry. Other uses include the
manufacture of other silver salts, mirror production, silver
plating, as a component of inks, and as a disinfectant.
Sodium Bicarbonate
-------
Figure 1S, FLOW DIAGRAM FOR TYPICAL PRODUCTION OF SILVER NITRAT1
DISTILLED
WATER
SILVER
I
NITRIC
ACID
REACTOR
SILVER NITRATE
SOLUTION
EVAPORATOR
1
CRYSTALLfZift
I
CENTRIFUGE
IMPURE
SfL¥ER NITHATi
CRYSTALS
REDISSOLVER
SILVER
NITRATi
SOLUTION
CRYSTALLIZER
CENTRIFUGE
PURfFIED
SILVER NITRATi
CRYfTALS
DRYER
fSTt
CRYSTALS
PACKAGING
TO SALES
48
-------
Description. The sodium bicarbonate (NaHCOSJ
manufacturing industry presently contains three known
plants, none of which discharges to a POTW. Two of the
plants discharge directly to surface waters, and one plant
is achieving zero discharge of process waste water. These
three plants accounted for 88% of the total U.S. production
in 1973 of 250,000 metric tons (275,000 short tons). Since
1973, a fourth plant, accounting for the remaining 12% of
the 1973 O.s. production, has closed down its operation
(Reference 6}.
Manufacturing Process. Sodium bicarbonate, also known as
bicarbonate of soda and baking soda, is produced by the
reaction of sodium carbonate (soda ash) with water and
carbon dioxide under pressure:
Na2CO3 * H20 + CO2 = 2NaHCO3
The commercial material is prepared by dissolving soda, ash
with stirring. Then, insoluble impurities are settled out,
and the solution is cooled to about 40°G (1Q4°F).
Carbonation of this solution with purified kiln gas is
carried out in a tower similar to that used in the Solvay
process. As the carbon dioxide is adsorbed, a suspension of
sodium bicarbonate forms. The slurry is filtered and the
cake washed on rotary drum filters. The cake is the dried
and packaged for sale. This standard production process is
illustrated in Figure 20.
Sodium bicarbonate is also a minor byproduct of soda-ash
manufacture.
sodium bicarbonate is usually sold at least 99.0% pure to
meet the requirements of the U.S. Pharmacopoeia (Reference
8). The material is used in foods; chemicals;
Pharmaceuticals; fire extinguishers; and a variety of other
industries, such as rubber, plastics, and paper and textile
processing.
Sodium Fluoride
Industry Description. There are four known plants presently
manufacturing sodium fluoride (NaF) in the United states.
The three plants for which sufficient data are available are
discussed in this document. These three plants account for
the majority of the U.S. production in 1974 of 6,455 metric
tons (7,100 short tons) .
Of the four sodium fluoride producers, none discharge
process waste water to a POTW, All of the plants achieve
-------
Figure 20. SIMPLIFIED FLOW DIAGRAM OF SOLVAY PROCESS FOR
PRODUCTION OF SODIUM BICARBONATE
- "^ p|,
SETTLING __ y I
TANK |p
J FILTER •*- E
WASTE ,,
RBON
3XIDE
JRYER^ pJUSSJo
T
TO SALES
SOURCE: REFERENCE 2
-------
zero discharge or discharge directly to surface waters after
treatment.
Manufacturing Processes . Sodium fluoride is produced in
this country by three different chemical reactions:
2HF + Na2CQ3 = 2NaP + H2O 4 CO2
Na2SiF6, + 6NaOH = 6NaP + Na2jSiOjJ + 3H2O
WaOH + HF * NaF * H2O
As can be seen by the above equations, the first and third
processes produce no byproducts. consequently, simple
settling, filtration, and drying result in a sodium fluoride
product of about 99% purity. The second process produces a
sodium silicate byproduct which must be segregated from the
sodium fluoride product by use of a multistage separator. A
generalized process flow diagram for sodium fluoride
production is presented in Figure 21.
The principal uses of sodium fluoride are in the manufacture
of rimmed steel, for the f luoridation of water, in heat-
treating salts, for pickling stainless steel, in soldering
and metallurgical fluxes, as a preservative for wood, in
adhesives, as an insecticde, in the manufacture of coated
papers, as a fluxing agent in vitreous enamels, and as an
antiseptic in breweries and distilleries.
51
-------
Figure 21, GENERALIZED FLOW DIAGRAM FOR PRODUCTION OF
SODIUM FLUORIDE
SODIUM SOURCE
FLUORIDE SOURCE
f
REACTOR
t
"*•- COOLING I
^ WATER I
I
PHYSICAL
SEPARATOR
PRODUCT
t
DRYIR
T
VINT
STORAGE
AND
PACKAGING
TO SALES
I RECYCLE
I
I
SEPARATOR ^ I
' OVERFLOW ~^~~
wn-r- '&TER
WAST »'ATER
52
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SECTION IV
INDUSTRY SOBCATEGORIZATION
IHTRODOCTIOE
General
For the purpose of establishing pretreatment standards for
dischargers to POTWs, the Inorganic Chemicals Manufacturing
Industry category has been segmented into subcategories
based on the specific inorganic products manufactured.
Although similar waste water constituents may be generated
from various product groupings and may be treated to similar
concentrations, water requirements are specific for each
chemical manufacturing process. Guidelines based on
production volume must reflect this difference.
Additional consideration has been given to the need for
further subcategorization within the industry. To this endf
this section describes the characteristics of those segments
of the Inorganic Chemical Industry covered in this document
which discharge to POTWs, or are most likely to discharge to
POTWs, and presents the rationale employed to decide whether
further subcategorization is warranted.
Objectives of gubcategorization
The objective of subcategorimation of the Inorganic chemical
Industry segment discharging to POTWs is to establish
recommended pretreatment standards for existing and new
sources which are specific and uniformly applicable to a
given subcategory,
FACTORS CONSIDERED
Factors taken into consideration for further
subcategorization of the segments of the Inorganic Chemical
Industry discharging to POTWs included geographic location,
land availability, plant size, process employed, types and
volumes of waste water generated, and types of POTWs
receiving discharges.
FACTORS INFLUENCING STOCATEGORIZATION -IN ALL CHEMICAL
SUBCATEGORIES
Approach to Subcateqorization
The first subcategorization step was to examine the chemical
subcategories and evaluate the factors influencing
subcategorization for the industry as a whole. The factors
53
-------
considered important in subcategorization of the industry
are listed above under "Factors Considered, " Following is a
discussion of each of the general factors considered for all
chemical subcategoriea. (For some chemical subcategories,
additional factors were also considered.)
Geographic jiocation,
The chemical industry, as a whole, is widely dispersed
throughout the country. The raw-material source, additional
chemicals produced, and product markets greatly influence
plant location. Those plants discharging to POTWs are
usually located in or near large urban areas which have
municipal sewer systems. However, the location of the
facilities does not influence the characteristics of waste
water treatability.
ILand
Plants discharging to PQTWs are generally located in or near
large urban areas which, typically, have sewer systems. The
use of impoundment and settling ponds for pretreatment and
control of waste water may often be difficult, due to a lack
of available land. However, these problems are common to
most POTW dischargers within the inorganic chemical
industry.
Plant Size
Plant size and production were not found to affect the
characteristics of the wastes produced. Differences in
plant size may influence the economic impact of recommended
technologies, but not the nature of the effluents and their
treatment. Thus, subcategorization by plant size was
considered unwarranted.
Process
Within the inorganic chemical industry, the basic unit
operations employed are often the same. They include
digestion, evaporation, crystallization, filtration, etc.
However, within each chemical subcategory, the raw material,
process sequence, controls, recycle potential, handling, and
quality control vary greatly. Therefore, subcategorization
by process is not warranted,
Types and Volumes of Wastewater
Water use and waste water generation are dependent upon
choice of process employed or process requirements, the use
of noncontact cooling, the potential for reuse or recycle of
-------
water, and housekeeping practices, This factor was
determined not to be the most direct or most suitable means
of subcategorization.
Tyg.es of POTWs
Most municipal treatment plants have primary settling or
secondary biological treatment systems. Treatment is
directed at the reduction of suspended solids and BOD, The
biological treatment systems are much more susceptible to
upsets caused by the presence of potentially toxic material
in the influent than are primary treatment systems.
However, both offer very little reduction of metals and
other pollutants commonly found in industrial wastes,
Physical/chemical-treatment systems which do offer treatment
of industrial wastes are rare. Because POTW dischargers
within the industry discharge only to primary or secondary
treatment systems, neither of which offers significant
treatment of industrial pollutants, subcategorization on
this basis is considered unwarranted.
FACTORS INFLUBNCING SUBCATEGORIZftTION BY CH1MIC&I,
SUBCaTEGORY
Alumipum Chlorid_e
Geographic Ijocatign. From a geographical standpoint, only
one aluminum chloride plant is located West of the
Mississippi, and seven of the remaining Eastern plants
reside in New York, New Jersey, and Ohio. Though the
producers of this salt are situated largely within
municipalities, there were no POTW dischargers reported for
this subcategory.
None of the factors related to geographic location, such as
rainfall/ evaporation rates or topography, was found to
constitute a basis for subcategorization,
Land Ay ailab i jLjty-. This criterion is frequently a limiting
factor, particularly in urban areas, where waste water
treatment (pretreataient) may require large areas for
evaporation, impoundments, or settling basins. However, the
relatively low volumes of waste water generated at these
plants precluded the need for large settling basins and
negate the need for subcategorization of aluminum chloride
plants on the basis of land availability.
Plant Size. Plant size may or may not be related to waste
water volume, but it is generally not a factor in terms of
waste water quality. From information collected during this
55
-------
study ,ex there"' appears to be no connection between aluminum
chloride plant size and waste water character or treatment.
grocegg Employed. In the aluminum chloride manufacturing
industry, the processes for synthesizing hydrous and
anhydrous products are different. In addition, emissions
generated by both processes are dissimilar. Both processes,
however, frequently employ wet scrubbers, which generate
similar wastes. Therefore, the processes employed for
producing aluminum chloride do not justify
subcategorization.
Types and Volumes of Wastg Water. Emissions-control
scrubber water is the marfor source of process waste water
reported for the aluminum chloride industry. Though
discharge volumes may vary, depending upon the degree of
recycle, all wastes are amenable to pretreatment by
convention pH adjustment and settling to reduce pollutant
concentrations.
Emiasigns-Control Practices. Emissions-control practices
vary between plant locations and product type. Usually
where chloride-rich product is manufactured, emissions
control is a necessity. However, a given plant may produce
white or gray aluminum chloride in the same furnace that
recently produced the yellow salt. These emissions may or
may not require scrubbing, depending on air ordinances.
Therefore, subcategorization on the basis of emissions-
control practices becomes very unmanageable, and this factor
has been rejected as a criterion for subcategorization of
aluminum chloride plants.
life§ of PgTW. Since there are no known POTW dischargers in
this subcategory, there is no need for subcategorization on
this basis*
Aluminum sulfate
geographic Loca.tion. Alum (aluminum stalfate) plants are
well dispersed throughout the nation. Since there are no
locational differences, none of the factors related to
geography (such as rainfall/evaporation rates and
topography) was found to constitute a basis for
subcategorization.
Land Availability_« Land availability can be a limiting
factor in cases where settling ponds are required for
treatment and recycle purposes. However, since at this time
no POTW dischargers have been identified, subcategorization
based on land availability is unwarranted.
56
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Plant. Size* Plant size may or may not be related to waste
water volume, but it is generally not a factor in terms of
waste water quality. From information collected during this
study, there appears, to be no connection between plant size
and waste water characteristics or treatment.
Process Employed. The basic process for alum production is
constant throughout the industry, though many minor process
modifications exist. However, these modifications do not
result in waste water characteristics or volumes which would
remain untreatable by currently practiced technologies.
Therefore, process employed cannot be considered a factor
for subcategorimation.
Types and Volumes of Waste Water. Process modifications,
raw material, and waste recycle produce qualitative and
quantitative differences in waste water among alum
producers. However, the technologies available to reduce
pollutants are applicable to all wastes generated by the
industry. Therefore, there is insufficient basis for
subcategorization.
Types of POTW. Since there are no known POTW dischargers in
the subcategory, there is no need for subcategorization due
to this factor.
Calcium Carbide
The factors of subcategorization (geographic location, land
availability, plant size or age, production methods, waste
volume and content, etc.J do not vary widely in the portion
of the calcium carbide industry which is regulated by the
Inorganic Chemical Industry category. Therefore,
subcategorization of the manufacture of calcium carbide is
not considered necessary.
Calcium Chloride
Geographic Location. As mentioned in section III, calcium
chloride producers are located throughout the U.S., with no
obvious regional trends. As would be expected,. plants
utilizing natural brines are located near the resource.
Several smaller plants operating on a batch basis are
located near or in cities, and these plants are prime
candidates for POTW-discharge status. However, only one
such discharger has been identified, and this factor does
not constitute a basis for subcategorization.
In addition, none of the factors related to geographic
location (such as rainfall/evaporation rates and topography)
was found to be an adequate basis for subcategorization.
57
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Land. Ay a 41 gb 11 it y. Generally, smaller plants which might be
located in municipalities produce limited quantities of
product from relatively small volumes of raw materials.
This situation almost precludes any attendant problems which
might result from land availability. At larger plants
studied, plant operators report that land availability is no
major problem, because these plants were designed with large
holding and settling ponds in mind, and additional space for
expansion and development was set aside for this purpose.
Plant Size. There is a large variation in plant production
size in the calcium chloride manufacturing industry. Annual
plant capacities vary from less than 270 metric tons (300
short tons) to about 450,000 metric tons (500,000 short
tons). The larger plants are usually associated with
natural salt deposits in Michigan or with the solvay
process, but this does not. negate the existence of small
natural brine and small byproduct producers. A relatively
large calcium chloride producer is unlikely to utilize a
POTW because of the surcharge structure. The three largest
producers are direct dischargers. Therefore, plant size
almost certainly influences the quantity and quality of
wastej for the purpose of establishing pretreatment
standards, however, there is no justification for
subcategorization.
.Process Emglc-yed. In this industry, the process employed is
a direct consequence of the raw material. The processes
have been described in Section III, and it is evident that
much variation exists from plant to plant. The raw material.
and the process bear directly upon waste water quality.
Though waste water quality varies with process, it is
evident that pH control is the common factor for all waste
water. Based upon this logic, there is no basis for
subcategorization due to process employed.
Types and volumes of Haste. Water. As discussed above, the
waste water quality, as well as quantity, varies from plant
to plant, in fact, some processes generate no waste water.
However, a common pretreatment (i.e., pH control) is
sufficient to render all waste waters amenable to treatment
by POTWs. Therefore, the types and volumes of waste water
are not sufficiently different to warrant subcategorization.
Types of POTW. There is only one known POTW discharger in
the calcium chloride manufacturing industry. The
characteristics of this POTW have been described in Section
III, and it is evident that pretreated calcium chloride
waste water can be accommodated at any type of biological or
physical/chemical POTW. Therefore, POTW characteristics do
not form sufficient basis for subcategorization.
58
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Cogper jCupric) sulfate • •
Copper (cupric) sulfate plants are not concentrated in
specific areas of the country. The plants are usually
located in conduction with copper refineries,
The plants studied for this report have different amounts of
discharges, ranging from none to treated wash water. The
copper sulfate manufacturing industry uses the same type of
raw materials in the different plants; copper shot, scrap
copper, sulfuric acid, and water. The scrap used at some of
the plants (copper wire, for instance) is of high quality
and does not present any significant waste problems of its
own. The processes used in the plants are similar;
therefore, process waste waters from the processes are
similar.
Due to the potential similarity of waste waters from copper
sulfate producing plants, subcategorization is not
considered necessary.
Iron (Ferric) Chloride
Geographic Location. The two iron (ferric) chloride
manufacturing operations discharging to POTWs are located
within large metropolitan areas. AS such, there is no need
to subcategorize based on geographic location.
Land availability. Typically, POTW dischargers are located
in urban areas, where the amount of space available for the
installation of pretreatment equipment may be limited.
Facilities which require a great deal of land—most notably,
settling ponds—may be difficult to install. These problems
are common to all known indirect dischargers in the ferric
chloride industry. Therefore, there is no need to
subeategorize based on land availability.
Plant Size. The two ferric chloride manufacturing
operations discharging to POTWs are of approximately the
same size. Therefore, there is no need to subcategorize the
ferric chloride manufacturing industry on the basis of plant
size.
Process Employed. Basic ferric chloride manufacture
involves the reaction of pickle liquors, iron, chlorine,
hydrochloric acid, and water to produce a 40% ferric
chloride solution. The solution may or may not be filtered
to remove impurities. Any variations in raw-material mix,
the reaction process itself, and filtration techniques have
little effect on the nature of wastes produced, nor do they
59
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affect waste treatability. Therefore, subcategorization is
unwarranted.
Types and Volumes of Waste Waters. Because some variability
is found in the types and quantities of waste waters
generated during the production of ferric chloride, the
design of a pretreatment system must be tailored to each
operation. However, the general types of treatment employed
and the treatability of the wastes remain the same.
Therefore, there is no need to subcategorize the industry
based on the types and volumes of waste waters generated.
Types of POTW. One of the ferric chloride plants discharges
to a primary municipal treatment plant. The other
discharges to a secondary, activated-sludge plant. However,
plans are underway at the primary plant to upgrade the
system to a secondary, biological-treatment system.
Therefore, subcategorization based on types of POTWs is not
necessary.
Lead Monoxide
Factors taken into consideration as possible justification
for further subcategorization of the lead monoxide
manufacturing industry included:
(1) Geographic location
(2) Land availability
(3) Plant production and size
(H) Type of processing employed
(5) Types and volumes of waste generated
(6) Topography
(7) Climate and rainfall
(8) Facility age
(9) End product(s)
No POTW dischargers were identified within the lead monoxide
industry. The basic factors which determine whether an
industry discharges directly or discharges to a POTW are
economics and availability of a POTW.
In the lead monoxide manufacturing industry, most criteria
for subcategorization bear directly upon one basic factor:
the source of process waste water. General factors, such as
end products, climate, rainfall, topography, and facility
age, proved to be of minor importance as criteria for
additional subcategorization. All segments of the lead
monoxide subcategory—whether discharging to POTWs,
discharging directly, or with no discharge or process waste
• water--use some form of lead metal as the raw material. The
various manufacturing processes are very similar in that
60
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they all heat the lead and, by subjecting the molten lead to
air at controlled temperatures, oxidize it to form lead
monoxide. With lead monoxide manufacturing plants located
from coast-to-coast, there are large variations in land
availability, water use, facility age, and treatment
technologies employed. However, when the relatively small
process waste water flows generated from plant washdown and
compressor blowdown are taken into consideration, these
differences within the industry do not justify any further
division of this subcategory. Thus, all lead monoxide
plants discharging process waste waters are considered
within the same subcategory.
Nickel sulfate
Geographic; Location. The three known nickel sulfate
producers discharging to POTWs are located in or near large
metropolitan areas. Consequently, there is no need to
subcategorize the industry based on geographic location.
Land Avai3.abj.lit%. Typically, POTW dischargers are located
in urban areas, where there is often very little space
available for the installation of pretreatment equipment.
Facilities such as settling ponds, which require a great
deal of land, may be difficult to install. This problem is
universal to all nickel sulfate producers discharging to
POTWs. Therefore, there is no need to subcategorize based
on land availability,
Plant Size. The establishment of a criterion for
subcategorization based on plant size is unwarranted. Plant
size has no effect on the nature of waste water generated,
nor on its treatability.
Process Employed. Basic nickel sulfate manufacture involves
the reaction of nickel metal, nickel oxide, or waste nickel
materials with sulfuric acid, Various techniques are
employed to purify the nickel sulfate solution. In
addition, both nickel sulfate solutions and crystalline
nickel sulfate hexahydrate are produced. Variabilities in
raw material, process, and purification techniques have
little effect on the nature of wastes produced, nor on their
treatability. Therefore, subeategorization is unwarranted.
Types and • Volumes of Waste Waters. Because some variation
Is found in the types o?~waste water generated during the
production of nickel sulfate, pretreatment systems must be
tailored to individual plant requirements* However, the
general pretreatment technique employed and the waste water
treatability remain the same. Therefore, there is no need
61
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to subcategorize the nickel sulfate industry based on the
types and volumes of waste waters discharged.
Types of POTW* All three known POTW dischargers direct
their' process waste waters to secondary, biological-
treatment plants. Therefore, subcategorization based on the
receiving POTW is unnecessary.
and oxygen
Geographic Logatiort and Land Availability. Neither of these
factors is considered valid ground for subcategorization,
since the air-separation process for production of nitrogen
and oxygen requires no geographically confined raw material,
nor does it require a vast land area for efficient
manufacture of product or handling of process waste water.
giant Size . Plant size is not considered to be a
significant factor for rationalizing subcategorization,
since the types and quality of wastewater being produced are
not dependent on facility size or production capacity.
Process Employed. Although minor differences in process
exist with respect to type of air compression, process
cooling, and air purification, no one modification is so
distinct that it would necessitate special subcategorization
on the basis of process employed. The Linde process of air
separation via molecular sieves is not convered in this
document, because it is generally used primarily by small
on-site producers and represents an insignificant percentage
of total production- Therefore, process is not considered a
factor for subcategorization in this supplemental document.
Types and itolumes of Wastj; Water. Contact process wastes
throughout the industry are generally produced in such
limited quantities that handling and treatment require no
distinctive or elaborate technology.
Types of POTW. Due to the fact that limited volumes of
contact process waste water (principally, oily compressor
condensate) are produced and are frequently mixed with
noncontact cooling water after treatment, the dilution
factor is such that the type and size of POTW handling the
wastes need not be specifically adaptable to accommodate
these discharges.
Potassium Pi chr ornate
Further subcategorization of the potassium dichromate
subcategory is unnecessary since, at present, it consists of
only one known manufacturer.
62
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Potassium Iodide ' • '• •
Based on information acquired from telephone contacts with
members of the potassium iodide manufacturing industryf
review of the available literature, and compilation of data
provided by industry, it was determined that none of the
factors given earlier in this section warrants further
subcategorization of the potassium iodide subcategory.
The manufacturing processes employed by the four producers
of potassium iodide do not differ significantly with respect
to the reagents used or the character and treatability of
the waste water associated with production. In all
instances, this waste water does not originate directly from
within the production process, but rather is the result of
water used for noncontact cooling, equipment washdown, or
cleanup of spills.
Factors such as plant size, age, and geographic location
have little effect on the technology of treatment in
general. Likewise, due to the nature of the waste water
discharged, the type of POTW receiving these discharges was
not found to warrant further subcategorization.
Silver Nitrate
No silver nitrate manufacturing operations have been
identified as discharging process waste water to a POTW. No
rationale was found for subcategorization of those silver
nitrate producers discharging directly to surface waters;
therefore, subcategorization of any future POTW dischargers
is not indicated.
Sodium Bicarbonate
Geographic Location. For discharge to a POTW to be a cost-
effective method for the treatment of sodium bicarbonate
manufacturing process waste water, .the manufacturing
facility must be located in or near a sewered area serviced
by a POTW. As such, there is no need to subcategorize the
industry based on geographic location.
Land Availability. Typically, POTW dischargers are located
in urban areas, where there may be very little space
available for the installation of treatment equipment.
Facilities such as settling ponds or waste water-
impoundment-areas, which may require large areas of land,
may be difficult to install. Since this problem is common
to most POTW dischargers, there is no need to subcategorize
based on land availability.
63
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giant Size. The establishment of a criterion for
subcategorization based on plant size is unwarranted. Plant
size or production has no effect on the nature of the waste
water generated, nor on its treatability.
Types and Volumes of Waste Water. Any significant
differences in the quantity and quality of process waste
water can be attributed to the use of water recycling and to
good housekeeping practices, since the manufacturing process
is standard throughout the industry. Therefore, there is no
need to subcategorize based on the types and volumes of
waste waters produced.
Types of. POTW. There are presently no known plants
discharging sodium bicarbonate process waste waters to
PQTWs. However, one plant has plans under development to
discharge process waste water from sodium bicarbonate
production to a POTW beginning in 1979,
Sodium Fluoride
Geograghic Location. For discharge to a POTW to be a cost-
effective method for the treatment of sodium fluoride
manufacturing process wastewater, the manufacturing facility
must be located in or near a sewered area serviced by a
POTW. This is the case only in metropolitan areas; as such,
there is no need to subcategorize the industry based on
geographic location.
Land Availability. Typically, POTW dischargers are located
in urban areas, where there may be limited space available
for the installation of treatment equipment. Facilities,
such as settling ponds, which require a great deal of land
would be difficult to install, since this problem is common
to most POTW dischargers, there is no need to subcategorize
based on land availability.
Plant Size. The establishment of a criterion for
subcategorization based on plant size is unwarranted. Plant
size has no effect on the nature of waste water generated,
nor on its treatability.
Tyjges_ an.d Volumes of Waste Water. Both sodium fluoride
manufacturing processes which produce a process waste
discharge typically involve a batch reaction of caustic soda
(sodium hydroxide) with a fluoride source (hydrofluoric acid
or sodium silicofluoride). While some variation is expected
in the character and type of waste water generated during
the production of sodium fluoride, the waste water can
typically be characterized by high concentrations of
suspended solids, dissolved solids, and fluoride. The
-------
general pretreatment techniques employed and the wastewater
treatability remain the same. Therefore, there is no need
to subcategorize the sodium fluoride industry based on the
types and volumes of waste waters discharged,
Types of POTW. There are presently no sodium fluoride
manufacturing plants which discharge process waste waters to
POTWs. However, given the availability of a POTw, changes
in the economics of waste treatment caused by alterations in
discharge limitations, production, etc., may make it more
desirable for a plant with no discharge or a direct dis-
charger to become a POTW discharger. For this reason,
existing sodium fluoride plants were considered as potential
POTW dischargers.
SUMMARY OF RECOMMEMD1D SOBCATEGORIZ&TION
Based upon the preceding discussion and choice of final
subcategories, a summary of subcategories recommended for
those segments of the Inorganic Chemical Industry
discharging to POTWs and covered by this document is
presented in Table 3. The discussions in the sections which
follow address the subcategories presented in that table.
65
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TABLE 3. SUMMARY OF SUBCATEGORIES RECOMMENDED FOR INORGANIC
CHEMICAL INDUSTRY
SUBCATEGORY
SIC CODE
ALUMINUM CHLORIDE
ALUMINUM SULFATE
CALCIUM CARBIDE
CALCIUM CHLORIDE
COPPER (CUPRIC) SULFATi
IRON (FERRIC) CHLORIDE
LEAD OXIDE
NICKEL SULFATE
NITROGEN AND OXYGEN
POTASSIUM OICHROMATE
POTASSIUM IODIDE
SILVER NITRATE
SODIUM BICARBONATE
SODIUM FLUORIDE
1819
1819
1819
1819
1819
1819
1819
1819
1813
1819
1819
1819
1812
1819
66
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SECTION V
WASTE CATEGORIZATION
INTRODUCTION
This section discusses the sources of waste water within
that portion of the Inorganic Chemical Industry covered by
this document which discharges to POTWs. In addition, this
section identifies raw waste water constituents and
quantifies the constituents on the basis of concentrations
and loadings for each of the specified chemicals. where
data were unavailable to adequately define pollutant
loadings, concentration data alone were used to characterize
the waste water.
Data used for waste water characterization were -accumulated
from the widest possible base. Effluent data presented for
each subcategory were derived from historical effluent data
supplied by the industry and various regulatory and research
bodies and, in some cases, from current data for effluent
samples collected and analyzed during this study. Where
data from POTW dischargers were sparse or unavailable,
applicable data from direct dischargers were incorporated
into the characterization.
In this section, the principal specific water uses common to
all covered subcategories in the industry are briefly
summarized first. Then, for each subcategory, processes
employed and associated water use are described, sources of
waste water are discussed, and waste water characteristics
are given.
SPECIFIC WATER OSES IN AIL SUBCATEGORIES
General :
The principal water uses in inorganic chemical processing
plants are process water and noncontact cooling water,
The term "process waste water" means any water which, during
manufacturing or processing, comes into direct contact with
or results from the production or use of any raw material,
intermediate product, finished product, by product, or waste
product.
Process water often comes from several different sources in
a chemical plant. Contact cooling or heating water usage
includes quenching, slurrying, barometric condensers,
contact steam drying, etc. Transport water is often used
for transporting reactants or products to various unit
operations in either solution, suspension, or slurry form.
67
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Contact wash water usage includes ore washing to remove
fines, filter cake washing to remove impurities, cleaning of
insoluble product vapors, and absorption processes in which
water is reacted with a gasseous material to produce an
aqueous solution. Other miscellaneous water uses include
floor washing and cleanup, storage and shipping tank
washing, pump and vacuum seals, ion exchange regeneration,
etc. Product water generally is that which stays with the
product as an integral part,
The term "noncontact cooling water" means any water used for
cooling which does not come into direct contact with any raw
material, intermediate product, waste product, or finished
produce. If, the water is used without contacting the
re^ctants, such as in a tube in shell heat exchanger or
trombone cooler, the water will not be contaminated with
process-waste water pollutants. Noncontact cooling water is
generally either recycled cooling water which is cooled by
cooling towers or spray ponds, or once-through cooling water
whose source is generally a river, lake, or tidal estuary.
PROCESS-WASTE CHARACTERIZATION FOR ALUMINUM CHLORIDE
SUBCATEGORY
Process Description and Water Uge
Anhydrous aluminum chloride is synthesized largely by
reacting chlorine with molten aluminum and condensing the
resultant aluminum chloride vapors. The salt is formed by
digesting aluminum oxide in hydrochloric acid and then
purifying the solution which results. Water usage
associated with both product types falls into three major
groupings?
Process water—which includes uses such as
Dilution for process solutions
Emissions control
Water-treatment reagent preparation
Equipment and plant washdown
Leaks and spills (associated cleanup)
Noncontact Cooling Water—which includes
water involved in
Boiler and steam generation
Compressor cooling and condensate
Furnace-jacket cooling
Potable Water—which includes sanitary water
sources of Wastewater
68
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Figure 22 is an overall schematic of water use at Plant
19101, which produces both hydrous and anhydrous aluminum
chloride. The 74.6 cubic meters/day (19,700 gpd) volume of
process water is consumed by emissions control, washdown,
and hydrous product. The two sources of process waste water
are emissions scrubbing and plant washdown, which result in
a daily waste water volume of 50.7 cubic meters (13,400
gal). All wastewater sources, including runoff, are
combined for treatment and discharge.
Wastewater Characteristics
During anhydrous aluminum chloride production, the furnace
fumes are vented to a condenser to recover the product,
while the condenser tail gases proceed to emissions-control
devices. The emissions generated during aluminum oxide
digestion for production of the hydrous salt are also vented
to emissions-control devi.ces. The emissions generated
during production of both product types, but during
anhydrous production in particular, may or may not require
scrubbing, depending upon product grade and local air
regulations. The two types of scrubber waste waters (if wet
emissions devices are used) can be expected to have similar
waste characteristics, typified by low pH and elevated TDS
(total dissolved solids) concentrations. The low pH results
from hydrolysis of aluminum chloride and absorbtion of
hydrochloric acid and chlorine.
Scrap aluminum is frequently used during production of the
anhydrous salt, and the scrubber water can be expected to
resemble that generated by the secondary aluminum industry.
At secondary aluminum plants, molten aluminum is lanced with
chlorine to remove impurities (particularly, magnesium) in a
process called demagging. The emissions generated during
demagging are .collected in scrubbers and sent to waste.
Demagging-scrubber waste water contains many of the
impurities found in aluminum scrap; similarly, the scrubbers
from anhydrous aluminum chloride production collect
impurities from the raw materials. Since chemical analyses
of aluminum chloride scrubber waste water are not available.
Table 4 shows characteristics of raw demagging-scrubber
water from three plants in the secondary aluminum industry
which are POTW dischargers.
At plants where refined aluminum is used for production of
the anhydrous salt and where purified aluminum oxide is
employed for production of the hydrous salt, the scrubber
waste water is expected to exhibit much lower concentrations
of pollutants such as heavy metals. The low pH and high TDS
characteristics can be expected to remain, however.
69
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Figure 22. FLOW DIAGRAM SHOWING TYPICAL WATER USE IN PRODUCTION
OF ALUMINUM CHLORIDE (PLANT 19101}
GROUND WATER
lOBm3/*!*
< 28,700 apd)
SANITARY;
COOLING WATER:
a7m3Mw
(7,200 «id)
S6PTIC SVSTOfc
3iD3Atay
(800 MX))
COOLING TOWER
•XI
O
PROCESS WATER:
7i.Bm3,'tl,r
(1S.7DOBPC1)
TO ATMOSPHEHE
j >
EVAPORATION LOSS:
BOILEfl FEEDWATER.
*ra3Al^
d^OOgpdl
STEAM GENERATION
PROCESS HEATING.
4m3/(fay
RAINWATER RUNOFF;
wes>3W«y
(43,900 apdl
COND HSATE
AASTEWATCR TREATMENT:
-DIRECT DiKHABRE-
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TABLE 4. RAW WASTE CHARACTERISTICS OF CHLORINE DEMAGGING
SCRUBBER WASTEWATER FROM SECONDARY ALUMINUM INDUSTRY
PARAMETER
pH
TSS
Oil and Grease
COD
Al
Cd
Cr
Cu
Pb
Ni
Na
Zn
Chloride
Fluoride
CONCENTRATION (mg/l)
PLANT A*
1.65«*
934
<1
—
474
0.18
0.23
4.82
0.89
0,06
17.6
12.0
3.S83
<0,11
PLANT Bf
3J5»»
138
1
169
16,600
1.82
0.03
0.06
0.20
<0.02
26
38.7
22,500
<1
PLANT C«»
3.70*»
44
<1
—
1,8
0.076
0.44
0.05
0.02
0.03
13.8
2.38
442
0.33
'Average of seven samples.
t Average of eight samples.
"Average of four Samples.
71
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Total dissolved solids loadings will generally be higher in
aluminum chloride waste water, as opposed to secondary
aluminum waste water, because chlorination in the aluminum
chloride industry occurs over extended periods, and
techniques for reducing chlorine emissions are not highly
developed.
Routine plant washdowns may contain minor spills and leaks,
but these can usually be differentiated from major spills.
These wastes generally contribute appreciably to the total
process water flow. Raw waste characteristics are not
available for plant washdowns, but these wastes can be
integrated with other process waste water and treated
(pretreated) for discharge. Abbreviated raw waste
characteristics for a mixed scrubber, plant-washdown, and
boiler-condensate stream of 20t cubic meters/day (54,000
gpd) at aluminum chloride Plant 19102 are shown in Table 5.
PROCESS-WASTE CHARACTERIZATION FOR ALUMINUM SULFAT1
SUBCAT160RY •
Process Description arid Water Use
Alum (aluminum sulfate) is produced by reacting aluminum-
containing materials (usually, bauxite) with sulfuric acid.
The resultant solution is purified to yield a product which
can be sold or dehydrated to form crystals. Water usage
associated with alum production falls into three major
categories:
Process Water—which includes uses such as
Dilution for process solutions
Emissions control
Water-treatment reagent preparation
Equipment and plant washdown
Leaks and spills (associated cleanup)
Noncontact Cooling Water—which includes
water involved in
Boiler and steam generation
Compressor cooling and condensate
Reactor-vessel heating
Noncontact cooling
gota ble Wat er— -wh ich includes sanitary water
Sources of Wastewater
Figure 23 is a composite schematic showing many of the water
uses and waste water sources (excluding sanitary and
potable) originating from alum plants. The temperature and
72
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TABLE 5. CHEMICAL COMPOSITION OF COMBINED RAW WASTEWATERS FROM
PRODUCTION OF ALUMINUM CHLORIDE (PLANT 19102}
PARAMETER
pH
TSS
COD
Al
AVERAGE DAILY CONCENTRATION (mg/l)
1.5 to 9,0*
32
89
44
* Value in pH units.
73
-------
Figure 23. FLOW DIAGRAM SHOWING GENERALIZED SOURCES AND USES OF WATER
IN PRODUCTION OF ALUMINUM SULFATE
NONCONTACT
STEAM "
NONCONTACT r-
COOLING
WATER
RAW MATERIALS
t
DIGESTER
INSOLUBLE
"RESIDUES"
-RESIDUES*
I
SETTLER
I
FILTER
RESIDUE
WASHER
LIQUID ALUMINUM
SULFATi
RESIDUE
SLURRY
SETTLING
POND
EVAPORATOR
SOLID
ALUMINUM
SULFATE
i
PACKAGING
CLARIFIED OVERFLOW
WASTE
WASH WATER
1
TO SALES
^ NONCONTACT
"**" STEAM
•*- NONCONTACT
COOLING
WATER
NONCONTACT
COOLING
WATER
I
COOLER
PACKAGING
NONCONTACT
COOLING
WATER
TO SALES
74
-------
reaction rate in the digester can be grossly controlled by
use of steam and/or noncontact cooling water, but many
plants employ steam to hasten reaction time. Noncontact
cooling water is also used at a few plants where coolers are
employed to crystallize alum from solution.
The settling-tank underflow, which consists of compounds
such as silicon dioxide, titanium dioxide, aluminum oxide,
and aluminum sulfate (when bauxite is digested), is diverted
to a wash system at some plants for alum reclamation. The
residue-wash water is discarded after use at some plants.
At other plants where residue washing is not- practiced, the
muds may be fed to a settling pond or series of ponds, where
the transport 'water may be settled and discharged or
recyled, ' ¥essel~cleanout water' (not. shown in Figure 23} is
either discharged -or returned to the cycle, depending upon
plant practice.
Generally, the sources of process waste water are spent
liquor from settling ponds, wash water from residue washing,
and water from equipment and plant washdown. Each of these
streams contains residual sulfuric acid, but the two latter
streams are much-diluted versions of the former. ' These
streams are typically mixed before discharge.,
Wastewater characteristics
Table 6 is a compilation of chemical data representing waste
water discharges from various alum producers. The data have
been collected largely from Army Corps of Engineers
Discharge Application forms and represent total alum-plant
.discharges in most cases.- The data serve to provide a
general description of waste water quality. -As expected,
the waste water contains traces of many of the raw-material
constituents. These trace materials (such as metals) are
solubilized during digestion, mud washing, and settling in
ponds. Waste loads may vary due to inpurities in different
ores used,
PROCESS-WASTE • CHARACTER!Z AT FOR CALCIOM - CARBIDE
SPBCATEGOSY
Process Description and Water Ose
There is no process water involved in the production of
calcium carbide. Any contact of water with calcium carbide
results in the production of acetylene. The airborne wastes
from the calcium carbide process are all dusts (coke and
coal fines, limestone powder, and calcium carbide from the
packing station). Coke, coal, and limestone fines, which
75
-------
TABLE 6. CHEMICAL COMPOSITIONS OF RAW WASTEWATERS FROM PRO-
DUCTION OF ALUMINUM SULFATE
PARAMETER
PH
TDS
TSS
Al
Cd
Cr
Cu
Fe
Pb
Hg
Ni
Zn
Fluoride
Sulfate
CONCENTRATION (mg/II*
19201«
3,5»*
43,000
46,000
7,700
0,070
—
—
13
1.8
0,0054
-
1.0
_
5,000
19202*
3.8**
4,000
68
1,750
0.001
1.3
0.4
30.8
0,5
0,0001
0.6
1.0
0.66
2,750
19203*
—
_
-
>500
< 0.005
O.S
3,0
>500
0.37
0.0002
_
1i
_
_
19206*
_
—
_
—
<0.01
3
1
_
<0.1
< 0.001
2
0.4
—
21,500
•Based on data from Army Corps of Engineers Applications
^Industry data — liquid fraction of waste slurry.
** Value in pH units.
76
-------
constitute a significant fraction of the feed materials, may
be profitably returned to the system.
Dry bag collection of airborne fines eliminates waterborne
wastes and makes it possible to reuse these fines. It also
significantly reduces energy requirements by avoiding high
energy drying costs needed for recovery of water wastes.
Two of the three plants studied utilize dry dust collection
and recycle. The third plant employs a venturi scrubber on
furnace offgases. Table 7 characterizes the water use at
the three plants studied.
All cooling in calcium carbide production is accomplished by
noncontact systems. Noncontact cooling water is recycled or
lost by evaporation, except for small amounts of cooling-
tower blowdown. Figure 21 illustrates the process and water
use at Plant 19301. A small amount of water is used
intermittently at Plant 19301, at the furnace exit, to
decrease the temperature of the offgases to the collector.
This is a noncontact process, and all of the water is lost
by evaporation.
Water for noncontact cooling systems is generally softened
by ion exchange (zeolite process) before use. Softening
prevents excessive scaling in the cooling equipment.
Discharge of industrial noncontact cooling water to a POTW
does not have any deleterious effect on the operations of a
typical POTW.
Sources of Wastewater
The only source of process waste water in calcium carbide
production discharge is wet-scrubber waste water.
Only one of the plants studied (19303) uses a wet scrubber
to control the carbide-furnace emissions. At this site, the
scrubber waste water is pumped to a settling pond. Over 90%
of the water is eventually recycled to the scrubber system.
Only a slight discharge can be expected from the settling
pond.
Wastewater Character!stics
The available data defining the scrubber effluent after
settling at Plant 19303 are given below.
Intake Hater ^.^Scrubber ffater_Af ter.,Settling
pH (units) average 6.5 range: 7.1 to 9.2 average: 7.8
77
-------
TABLE 7. CHARACTERISTICS OF PLANTS PRODUCING CALCIUM CARBIDE
PLANT
19301
19302
19303
AVERAGE DAILY
PRODUCTION
metric tons
104
79
54
short tons
115
87
60
WATER USE
Noncontact
Cooling
m3/hr
4.73
7.87
94.6
gal/hr
1.250
2.080
25,000
Emission
Control
m^/hr
0
0
118
gal/hr
0
0
31,250
EFFLUENT
TREATMENT
None
None
Settling of scrubber
discharge
(400% recycle)
DISCHARGE
POTW*or
Direct
Direct
-
Direct
F
m^/hr
0.38
0
11.8
(494.6J
ow
gal/hr
100
0
3,125
(425.0001
•POTW = Publicly Owned Treatment Works.
-------
Figure 24, FLOW DIAGRAM FOR PRODUCTION OF CALCIUM CARBIDE SHOWING WATER USE (PLANT W3Q1)
•vl
U3
BAGHOUSE -RECYCLE-i
227ki/hf
I I (L>bU Ib/hr)
COKE p»i' pr
3.765 ka/hr *»- DRYER _
(8,300 Ib/hr j j *"*"
EVAPORATION
2,271 l/hr
(600 gal/hr) _
EVAPOfi
5,126kUr * IINTE
t
CALCIUM
CARBIDE
FURNACI
t "
| — 4— *-— 1
L J
~* BJ
r^
1 | PEECVCLE
WATER COOLING _^_ PRODUCT I *« „„,„,
4,/321/hr *• TOWER ^ i
(1.2SO aal/hr) f
14,353 l/hr
(1,1 50 gal/hr)
EVAPORATION
SLOWDOWN
379 l/hr
(100 gal/hr)
COOLER
t
CRUSHER
t
SCREENING
*
PACKAGING
t
PRODUCT
5,294 kg/Hr
(11,670 Ib/hr)
(800 Ib/hr)
i i
i L
181 kg/
(400 Ib/
(7 hour
ATIVE SPRAY
RMITTENTJ
814 Ifht
00 gal/hr)
CHOOSE "*
hr
(ir)
s)
WATER
(FOR COMPRESSOR)
2,271 Iftn
(800 gal/hr)
TO SALES
-------
TSS (mg/1) (data unavailable) range: 1 to 150 average: 10
The increase in pH is due to the presence of lime powder in
the furnace offgasea which is aolubilized in the venturi
scrubber, Eighty-percent removal of suspended solids by
settling can be expected. The scrubber water at Plant 19303
contains a relatively small amount of suspended solids after
settling. The suspended-solids concentration after settling
is well within the limits set by many POTW that handle
inorganic chemical process discharges.
PROCESS-WASTE CHARACTIRIZATION FOR CM.CIUM CHLOBIDS
SOTC&TEGORY
Procesg Description and Water Use
calcium chloride is manufactured from soda ash (sodium
carbonate^ wastes, obtained from natural salt deposits, and
produced by reacting calcium carbonate with hydrochloric
acid. Water uses associated with these various processes
falls into three major groupings:
Process Water—which includes uses such as
Dilution for process solutions
Transport media
Emissions control
Water-treatment reagent preparation
Equipment and plant washdown
Leaks and spills (including associated cleanup)
Noncontact Cooling Water—which includes
water involved in
Boiler and steam generation
Compressor cooling and condensate
Noncontact cooling
Potable Water—which includes sanitary water
Sources of Wastewater
The discussion which follows is largely concerned with the
use and sources of process waste water, although other major
types of water are mentioned.
since the scheme for production of calcium chloride from
natural brine at Plant 1910ft is so complex, only a simple
water-balance diagram is presented here, (See Figure 25J.
City water is introduced to the plant at an average daily
flow of 150 cubic meters (10,000 gal) for use as sanitary
and potable water and is discharged to the central water-
treatment system at the same relative volume, surface water
80
-------
Figure 25. FLOW DIAGRAM SHOWING WATER BALANCE FOR PRODUCTION OF CALCIUM
CHLORIDE FROM NATURAL BRINE (PLANT 19404)
CQNDfNSATE
270 m3/day
{72,000 gal/day)
CITY WATER
. fid
(40,000 gal/day!
SURFACE WATER
- 11,650m3/day -
{3,078,000 gal/day)
STEAM COMPENSATE
1,Q9Qm3/day —
(289,000 gal/day)
BRINE"
- 1,520 ms/day
(402,000 gal/day)
i
EVAPORATION
AND OTHER
PROCESS
STAGES
SANITARY WATER
TO TREATMENT
- ISO tn3/day
(40,000 gal/day)
CONCENTRATED
BRINE WASTE
- ii4 m3/day
(252,000 gai/day)
PRODUCT (WATER
CAPTURED)
- 310 m3/day
(82,000 gal/day)
CONDENSATE RETURN
1,460 m3/day
(38b,000 gal/day)
COOLING WATER TO RIVER
4,500 m3/day **
(3,050,000 gal/day)
•NOT RAW MATE RIAL
-------
is used, at a daily volume of about 11,650 cubic meters
(3,078,000 gallons) for cooling purposes, and most of this
water returns to a river. The difference is attributable to
evaporation,
The steam condensate, which enters the process at a daily
volume of about 1,090 cubic meters (289,000 gallons), is
recycled with a diversion to the cooling towers. The
condensate recycle apparently picks up water from the raw
brine solution. The water contained in the raw brine
solution (labelled "brine" in Figure 25) is partially
incorporated into the condensate recycle system, into the
product, and into the waste brine as a transport medium for
disposal.
The only source of process waste water is the concentrated
brine waste, which is disposed of via a well (which
penetrates the originating geologic formation) at a daily
discharge volume of 951 cubic meters (252,000 gallons)* The
concentrated brine is created by redissolving the salt
removed from the calcium chloride liquor. There are no
wastewater chemical characteristics available for this
stream.
Four other major water-use changes at the plant have helped
to reduce the discharge volume considerably, and two
process-waste water sources have been eliminated as a
result,
The Solvay process (production of soda ash) produces large
amounts of calcium chloride as a byproduct. Sodium
chloride, in addition to a small amount of calcium sulfate,
is present in the Solvay waste liquor. After calcium
chloride has been extracted from the liquor, dissolved
constituents are either returned to the soda-ash waste
stream or discharged.
At Plant 19101, overflows which occur during operational
upsets, and waste solutions which are not diverted to the
soda-ash waste stream, are discharged to surface waters.
Information on waste water quantity and waste water quality
is unavailable for these wastes because this normally
internal stream is not monitored? however, it is expected
that high TDS loadings will be present.
Calcium chloride production from calcium carbonate is a
rather simple process which generates no process waste water
other than washdowns. At Plant 19110, the insoluble
residues from limestone digestion are periodically removed
from reaction and settling vessels as a sludge, which is
routed to a water-treatment system for convenient solid-
82
-------
waste disposal. The treatment system handles waste water
from production of a number of organic and inorganic
chemicals, and it discharges to a POTW. However, there is
not a significant volume of calcium chloride waste water en-
trained in the sludge to consider this plant a POTW
discharger.
Plant 19412, which produces calcium chloride from a pure
calcium carbonate raw material, generates no process waste
water other than a daily reported volume of 1 cubic meter
(300 gal) for washdown which is treated before discharge to
surface waters. This treatment system also accommodates
waste from a number of co-located chemical production
processes.
wastewater Characteristics
At Plant 19106, which produces high-purity calcium chloride,
the only source of process waste water (excluding washdown)
is a scrubber which collects emissions generated during a
boil-down step. The waste water, which contains
hydrochloric acid, is mixed with other waste streams from
reagent-grade chemical production before being neutralized
and discharged to a POTW. The waste water has a low pH and
may contain high chloride concentrations, depending upon the
volume of gas scrubbed.
PROCESS-WASTE CHARACTERI2ATION FOR COPPER (CUPRIC) SQUATS
SUBCATSGORY
Process Description and Water Use
Plant 19506 mixes shot copper, 93$ sulfuric acid, water, and
air in a steam-heated oxidizing tower. The sludge produced
is returned to the on-site copper smelter for treatment.
The resulting copper (cupric) sulfate solution is sent to a
settling tank and then to an atmospheric crystallizing tank.
A process diagram is given in Figure 26. The mother liquor
front the crystallizing tank is eventually recycled to the
oxidizing tower. The crystals from the tank are
centrifuged, after which the product is.dried, screened, and
bagged. The liquor from the centrifuge is also recycled to
the oxidizing tower.
Mother-liquor solution at Plant 19506 is also sent to a
vacuum crystallizer as needed. The slurry resulting from
this stage is centrifuged and processed further. The water
from the barometric condenser connected to the vacuum
crystallizer is discharged without treatment.
83
-------
Figure 2ft FLOW DIAGRAM FOR PRODUCTION OF CUPRIC SULFATE (PLANT
oa
SULFURICACID
AND WATER
COMPRESSED _.
AIR Y
— COPPER SHOT
OXIDIZING
TOWER
t
SLUDGE
TO SMELTER
TOOTHiR
PROCESSES
SETTLING
TANK
ATMOSPHERIC
CRYSTALLIZER
WASHDOWN
WATER
1
MOTHER-
LIQUOR
TANK
±
DUST
COLLECTOR
1
WATER
CENTRIFUGE
VACUUM
CRYSTALLIZED
WATER •
STEAM
1
BAROMETRIC
CONDENSER
WATER
DRYER
PRODUCT
SCREENING
±
PACKAGING
TO SALES
-------
Plant 19505 uses copper shot, air, and electrolyte from an
adjacent copper refinery to produce copper sulfate. Upon
exiting the oxidizer reactor, the resulting mixture is
filtered and settled. The filter cake is returned to the
plant's smelter for recovery of precious metals. The copper
sulfate filtrate is processed through an evaporator, which
utilizes noncontact steam. The concentrated solution is
then sent to a crystallizer, which is cooled by noncontact
water. There is some recycling of the noncontact cooling
water. The copper sulfate crystals are separated from the
mother liquor by centrifugation* The mother liquor is
recycled to the evaporator, and the crystals are dried,
screened, and packaged.
Sources of Wastewat_er •.
The potential sources of waste water from copper sulfate
manufacture are: mother liquor from centrifugation, weak
liquor from the crystalIi2ers, washdown water, cooling
water, steam condensate, water from the barometric
condensers, and water from the dust-collection apparatus.
None of the plants studied has all of the above waste water
sources. Table 8 gives the characteristics and discharge
sources for the six copper sulfate producers covered by this
document.
The only process waste water discharged from Plant 19506 is
barometric condensate. It is discharged at an hourly rate
of 3H.7 cubic meters (9,166 gallons). There is no apparent
loss from the vacuum crystallizer to the barometric
condenser during normal operation. Once a year, the
condenser system is shut down for approximately 15 minutes.
At this time, an overflow of 19 liters (5 gallons) occurs.
Contamination of the barometric condensate from crystallizer
overflow in this quantity is negligible.
Wastewater Characterist ics . ' -'•
All waste waters are economically recycled at Plant 19505
except for the evaporator noncontact steam condensate and
the crystallizer noncontact cooling water. The condensate
and cooling water are discharged without treatment.
A third waste water is discharged separately at Plant 19505.
This discharge is highly variable, amounting to 18,900 to
22,700 liters (5,000 to 6,000 gallons) per day, and results
from spills and washdowns. This waste stream is treated
before discharge. Treatment consists of lime
neutralization, settling, and filtration* The sludge
produced in treatment is taken to an approved landfill site.
85
-------
TABLE 8, CHARACTERISTICS OF PLANTS PRODUCING CUPRIC SULFATE
PLANT
19501
19502
19503
19504
19505
19506
CuSO4
PRODUCT
Solution
Solution
Solution
Solution
Crystal*
Cryitalf
AVERAGE DAILY
PRODUCTION
metric tont
0.18
0.63
0.68
4J3
36.2
213
ibontWM
0.20
0.70
0.7S
5.00
40.0
24.1
COPPER
SOURCE
Sor ip
Snap
Scrap
Scrap
Scrip.
Shot
Shot
WATER USE
proms
Y«
Y«t
Yw
Y«
Yet
YH
noocotttoct
eaatine
No
No
No
No
Y*t
No
noncontKt
ttnm
No
No
No
No
YM
No
bwonntric
c^3micn>Bf
No
No
No
No
No
Yes
duit
control
No
No
No
No
No
Y«i
wKsridown
No
No
No
No
YM
Yn
DISCHARGE
pimiM*
No
No
No
No
YM
Yn
fOCIfQt
..^
-
-
- •
-NoncontKt ttaam
-TiMttdwah
00
-------
The available data for the washdown effluent at Plant 19505
are given below.
Concentration
' before ^treatment after treatment
copper average: 433 average: 0.48
range: 0,14 to 1.25
nickel average: 159 average: less than 0.5
pH (not available) 7.3 to 11.1 (pH units)
Figure 27 shows the production and treatment process used at
Plant 19505.
PROCESS-WASTE CHARACTER I ZAT ION FOR IRON (FERRIC* CHLORIDE
STOCATEGORY
Process Description and Water Use
Waste pickle liquors are preheated and reacted with iron,
chlorine, and hydrochloric acid to produce ferric chloride
solution. The solution is either filtered and packaged for
sale or filtered and evaporated to recover solid product. A
process diagram is given in Figure 28 for Plant 19601. At
some plants, no additional hydrochloric acid is used over
that in the pickle liquor.
At Plant 19602, .byproduct chlorine off gases from other on-
site operations are used as a chlorine source. The off gases
are cleaned with water in a contactor, to remove
particulates, before being directed to the ferric chloride
production process. Plant 19602 also employs a scrubber to
remove small quantities of chlorine gas not absorbed in the
ferric chloride solution. A process flow diagram for Plant
19602 is presented in Figure 29.
Water use during ferric chloride production includes:
(1) Process water used in the reaction to achieve the
desired solution specifications.
(2) Scrubber water to remove particulates from incoming
chlorine gas.
(3) Caustic scrubber water to absorb residual chlorine in
process tail gases. ' - .
Wash water to remove solid material from filters.
87
-------
Figure 27. FLOW DIAGRAM FOR PRODUCTION OF CUPBIC SULFATi (PLANT 19i05)
GO
Q3
ELECTROLYTE SOLUTION
COPPER SHOT
AIR
AIR i
J1J'
NONCQNTACT
COOLING WATER
SPILLS, WASHOOWN
NONCONTACTSTEAM
(CONTAMINATED)
OXIDIZING
REACTOR
I
FILTER
DECANT—
SETTLING
TANK
FILTER CAKE
TO SMELTER
*
EVAPORATOR
1
, L,
—KM.
&~.
(OTHER
.lauoft
TCLE-p-l
CRYSTALLIZER
f
CENTRIFUGAL
SEPARATOR
r
1
C001
ufA"
STEAM
CONDENSATE
PRODUCT
NEUTRALIZATION
TANK
t
FILTER
faess
-^-DECANT 1
SLUDGE
STORAGE
TAWK
1
SCREENING
t
FILTRATE
SLUDQE TO
LANDFILL
PACKAGING
f
TO SALES
-------
Figure 28. FLOW DIAGRAM FOR PRODUCTION OF FERRIC CHLORIDE {PLANT 19601)
CHLORINE
IRON
PICKLE,
LIQUOR1
IKUN-—I • r—•—
FEAM
+ i_y " "
STEAM
PREHEATER
HYDROCHLORIC
"ACID
•WATER
REACTOR
FILTER
NONCQNTACT
COMPENSATE
REACTOR
SLUDGE
f
FILTER
SLUDGE
FERRIC
-CHLORIDE-
SOLUTION
89
-------
Figure 29. FLOW DWGRAM FOR PRODUCTION OF FERRJC CHLORIDE
(PLANT 19602J
CHLORINE-BEARING GASES
to
o
WATER.
PICKLE
LIQUOR"
IRON-
i
CONTACTOR
1
REACTOR
TAIL
FERRIC
CHLORIDE
SOLUTION
30%
SODIUM —a.
HYDROXIDE J
GASES
SCRUBBER
" WATER "
CLEAN
GASES
"TO
ATMOSPHERE
LEAKS
AND
SPILLS
SCRUBBER
WATER
i
iwASHDOWNS
t _
WASTEWATER
DISCHARGE
PACKAGING
T
TO SALES
-------
(5) Miscellaneous washdown water.
Sources of Wastewater
Incoming Chlorine-Gas scrubber Water. Approximately 45
cubic meters (12,000 gallons) of waste water are generated
daily at Plant 19602 by cleaning particulates from incoming
byproduct chlorine gases. This operation is unique. In
general, industrial-grade chlorine is used as a raw material
for ferric chloride production, and no precleaning is
necessary.
Tail-Gas Scrubber Water. Residual chlorine present in tail
gases from the reaction process are scrubbed with 30% sodium
hydroxide in an absorption tower. The scrubber solution is
recycled except for a small purge stream.
Filter Wash Water. Solids removed from the raw ferric
chloride solution collect on the filter media and must be
removed. The filters are washed with water, resulting in a
slurry containing 15% solids. Plant 19601 daily generates 2
cubic meters (500 gallons) of this slurry,
Floor and Equipment Washings. Periodically, during
production, equipment and floor areas are washed to remove
spilled raw material and product. At Plant 19601, 1 cubic
meters (1000 gallons) of water are used each day for
equipment and floor washdowns. Plant 19602 daily uses 30
cubic meters (7,000 gallons) of water for routine
maintenance--even though its production is one tenth that of
Plant 19601. This variability is undoubtedly due to
differences in both general housekeeping practices and to
cleanup techniques.
Leaks and Spills. Leaks and spills can be a major source of
process waste water. At Plant 19601, 270 cubic meters
(72,000 gallons) of wastewater are generated each day from
leaks. Plant 19602, on the other hand, reports no leaks
from their ferric chloride manufacturing process. The
corrosiveness of process materials, equipment age,
maintenance, and plant-safety programs significantly affect
the frequency and degree of leaks and spills.
Wastewater Characteristics
General. Data on the chemical characteristics of waste
water generated solely from ferric chloride production are
unavailable. Therefore, a theoretical waste water was
developed, based on raw material characteristics, waste
water type, mode of generation, and limited historical in-
91
-------
formation. The rationale employed in characterizing the
waste water is presented below.
The major source of pollutants in waste water; generated from
ferric chloride production is the pickle liquor feed.
Besides iron, the pickle liquor contains a variety of trace
elements, including hexavalent chromium {Cr HSX), copper
(Cuj , manganese (Mn) , nickel (Ni), lead (Pb)» and zinc (Zn).
The chemical characteristics of a typical pickle liquor are
given in Table 9.
Analysis of each individual waste water generated during
ferric chloride production produced the conclusions which
follow.
Tail-Gas Scrubber Water. The tail-gas scrubber is used to
remove residual chlorine from process off-gases. Metals are
not expected in the tail gas except in very small
quantities—particularly, in light of the low reaction
temperatures encountered. Because sodium hydroxide is used
as the scrubbing medium, the pH of the scrubber waste water
is of concern. However, its effect will be minimized after
it is combined with other acidic process waste water.
Filter Wash water. It is known from historical data that
the filter wash water from ferric chloride production
contains 1516 solids. These solids include 50,000 mg/1 iron
and *,000 mg/1 miscellaneous materials (Reference 5). The
total concentration of trace metals in pickle liquor is
approximately 300 mg/1. If it is assumed that significant
percentages of the miscellaneous materials present in filter
wash water are the trace metals in pickle liquor, the
concentrations of these trace metals in the filter wash
water should be ten times their concentration in pickle
liquor.
Floor and Equipment Washings. Wastewater generated from
floor and equipment washings at other inorganic chemical
manufacturing operations has approximately 20,000 mg/1 total
suspended solids (TSS) and 36 mg/1 total trace metals.
Pickle liquor has 300 mg/1 total trace metals. If these
data are extrapolated to washings from ferric chloride
production, the waste water will contain 20,000 mg/1 TSS and
about one tenth the concentration of trace metals in pickle
liquor. It may also be inferred that the iron concentration
of floor and equipment washings will have one tenth the iron
concentration of pickle liquor.
Lgaks and Spills. Leaks and spills consist of essentially
pure pickle liquor and ferric chloride which have been
diluted with water. A spill, which may pose a health
92
-------
TABLE 9. CHEMICAL COMPOSITION OF TYPICAL IRON PICKLE LIQUOR
FROM PRODUCTION OF FERRIC CHLORIDE
PARAMETER
Cr (total)
Cu
Fe
Pb
Mn
Ni
Zn
CONCENTRATION
(ma/1)
13
10
9,000»
2.2
230
14
12
•Assuming 20% Fed2 in pickle liquor
93
-------
problem as well as harm equipment, will be diluted up to one
hundred times. Their occurance, however, is rare. Leaks,
on the other hand, are quite common and can be significant.
A pump seal may leak 1 I/minute (I gpm) of water, 10% of
that being process material. The resultant waste water will
thus contain one tenth the concentration of pollutants found
in pickle liquor.
The chemical characteristics of waste water generated from
ferric chloride production, based on the above rationale,
are presented in Tables 10 and 11. Table 10 presents the
waste water characteristics for a plant which has . a large
volume of leaks and spills, such as Plant 19601. Table 11
details the waste water characteristics of a plant, such as
Plant 19602, which has virtually no waste water associated
with leaks and spills.
PROCESS-WASTE CHARACTERIZATION FOR LEAD MONOXIDE SDBCATEGORY
Process Description and Water Use
At Plant 19701, lead monoxide is prepared by the Barton
Oxide Process, which is the same as Process 4 described in
Section III of this document. Dusts are controlled
throughout the process by the use of cyclones and dry bag
collectors. Floor dust is vacuumed. No process water is
used. Indirect cooling water is used for cooling the oxide
in the furnace-discharge conveyor. A process diagram is
given in Figure 30.
At Plant 19702, the lead monoxide manufacturing process is
the same as Process 2 described in Section III. Washdown of
dusts from plant surfaces is practiced at this plant. A
process diagram of Plant 19702 is given in Figure 31.
Sources of Wastewater
There are two sources of process waste water in the lead
monoxide manufacturing industry! plant washdown and
compressor blowdown, the major source being plant washdown.
Compressor blowdown is highly variable in composition and
quantity, although the quantity produced is small by nature.
Noncontact cooling is the only other water-using operation
in the lead monoxide manufacturing industry.
waatewater characteristics
Equipment and Plant Washdown. Equipment and plant
washdowns, dust control, and chemical spill cleanups are
generally considered to be housekeeping procedures. In the
lead monoxide manufacuring industry, these procedures are
-------
TABLE 10. CHEMICAL COMPOSITION OF AVERAGE WASTEWATER FROM
PRODUCTION OF FERRIC CHLORIDE (PLANTS WITH LARGE
LEAKS AND SPILLS)
PARAMETER
TSS
Cr (total}
Cu
Fe
Pb
Mn
Ni
Zn
CONCENTRATION
(mg/U
11,000
2.1
1.6
9,200
0.35
37
2.2
1.9
95
-------
TABLE 11. CHEMICAL COMPOSITION OF AVERAGE WASTEWATER FROM
PRODUCTION OF FERRIC CHLORIDE (PLANTS WITH MINIMAL
LiAKSANDSPliLS)
PARAMETER
TSS
Cr (total)
Cu
Fe
Pb
Mn
Ni
Zn
CONCENTRATION
lmfl/i)
33,000
14
11
13,000
2.4
2SO
15
13
-------
Figure 30. FLOW DIAGRAM FOR PRODUCTION OF LEAD MONOXIDE {PLANT 10701)
AIR
MOLTEN LEAD
ATOMIZER
TO SALES
i
*
SUBOX1DE
PRODUCT
AIR
CYCLONE
I
PRODUCT
STORAGE
FURNACE
SETTLING
CHAMBER
T
-------
Figure 31. FLOW DIAGRAM FOR PRODUCTION OF LEAD MONOXIDE
(PLANT 19702)
PIG LEAD
AIR-
COOLING WATER
VENT
VENT
MILL
ROTARY
OXIDIZING
FURNACE
(ULTRAF1NE POWDER}
DER
PRODUCT
SOURCE: REFERENCES
98
-------
necessary to control the fine lead oxide dusts formed in the
firing, milling, and handling operations. A significant
portion of the dusts and spills occurring in lead oxide
plants contains lead monoxide.
Dust control and cleanup may be practiced with or without
water. Ten lead monoxide plants use dry bag collectors and
dry vacuuming for dust control and cleanup. These 10 plants
are all zero dischargers. One plant employs wet dust
control and cleanup ("washdown11) and discharges the waste
water generated to surface waters.
Due to the nature of washdown waste water, its composition
and quantity may vary significantly from day to day, as well
as from one plant to the next. The composition of washdown
waste water is primarily dependant upon two factors;
(1) The types and amounts of equipment, products, reagents,
or other materials which the wash water directly
contacts.
(2) The volume and chemical characteristics of the clean or
unused wash water.
Actual chemical characteristics of a typical washdown waste
water from a lead monoxide plant are unavailable at this
time. However, sufficient data were available to allow
formulation of reasonable estimates of the chemical
characteristics of untreated washdown water at Plant 19702.
At Plant 19702, 85 to 90% reductions in total lead and
suspended solids are claimed due to the reaction of soluble
lead with sulfate ions. Approximately 373 kg (820 Ib) of
lead compounds are recovered daily from this treatment.
Since the daily process-waste water flow rate is known to be
348 cubic meters (92,000 gallons)» the concentration of
total lead can be calculated as follows:
Concentration of total lead * J, • MPB * R (1000)
in wash water E MPBO p
207 • 373 (1000)
(207416) 3H8
* 1170 mg/1
where E = Removal efficiency
99
-------
MPb - Molecular weight of lead
MPbQ= Molecular weight of lead monoxide
R = Recovery rate of lead compounds from
treatment (kilograms per day)
F = Plow rate of waste water
(cubic meters per day)
This estimate is based on the assumptions that most of the
lead compounds recovered are in the form of lead monoxide,
and that the lead removal efficiency is 85%f
Since lead monoxide dust is the major constituent found in
washwater and is fairly insoluble in the near-neutral pH
range, most of the lead present will be in the form of
suspended solids. For this reason, total lead
concentrations and total suspended-solids concentrations
will be the same for all practical purposes. This
assumption is supported by laboratory testing,- which showed
total lead removals of 92% for settlingpond effluent using
filtration Furthermore, untreated washdown wastewater can
be expected to be nearly the same as that of the water
source (pH 6.9).
The estimated chemical characteristics of untreated lead
monoxide plant washdown waste water discussed above are
summarized in Table 12.
Compressor Slowdown. The only source of process waste water
from lead monoxide production, other than plant washdown
water, is air-compressor blowdown. In most cases,
compressor blowdown is not considered a process waste water.
However, since the blowdown comes into direct contact with a
raw material, oxygen, it is a process waste.
Compressor blowdown is actually water condensate from the
humidity in air, oil and grease, other particulate matter,
etc., purged from the compressor. The amount of condensate
generated from compressors is highly variable, being a
function of compressor-air flow rate, humidity, temperature,
and elevation, but can be closely estimated as follows:
Basis: 0.907 metric ton (1.0 short tons) of lead
oxide product V, volume of air required » 45.6
cubic meters (1,610 cubic feet) at standard
temperature and pressure (STD)
100
-------
TABLE 12. ESTIMATED CHEMICAL COMPOSITION OF UNTREATED
WASHDOWN WASTEWATER FROM PRODUCTION OF
LEAD MONOXIDE (PLANT 19702)
PARAMETER
PH
TSS
Pb
CONCENTRATION
(mg/ll
6.9*
1,200
1,200
•Value in pH units.
101
-------
H * MW « p s 18 • p_
Ha p-p 29 p-p
where H = absolute humidity, kg water vapor/kg dry air
Mw = molecular weight of water, grains
Ma = molecular weight of air, grams
p - partial pressure of water vapor in air,
atmospheres
p » total pressure of the air water-vapor
mixture, atmospheres
At standard temperature and pressure:
H = 0.016 kg water vapor/kg dry air
vf specific volume of air = 0.82 cubic meter per
kilogram dry air
Volume of compressor condensate = 0.016 (1/0.82) (45.6)
(per-ton of lead monoxide product) = 0.89 liters
(0.23 gal)
It can be seen from this calculation that waste water flows
from compressor blowdown will be relatively small, even when
one considers larger lead monoxide producers and the fact
that, in actual practice, the volume of air required will be
significantly higher than theoretically predicted. As an
illustrative example, the daily volume of compressor
blowdown at Plant 19702 is estimated to be 0.13 cubic meter
(3tt.5 gallons) based on standard temperature and pressure,
three times the theoretical oxygen requirements. The
contribution of oil and grease from the above-estimated flow
of compressor blowdown would produce an oil and grease
concentration of less than 1 ppm in the effluent from Plant
19702.
The chemical composition of compressor blowdown is as
variable as the quantities produced. However, oil and
grease is usually the only pollution constituent present to
any appreciable degree, as indicated in Table 13.,
Oil and grease concentrations encountered in compressor
blowdown are a function of the compressor design and age.
There are basically two types of compressors; wet-type
compressors (which use oil to lubricate cylinder walls) and
dry-type compressors (which avoid contact of the gas with
oil). All wet-type compressors are of the reciprocating-
102
-------
TABLE 13. CHEMICAL COMPOSITION OF SLOWDOWN FROM TYPICAL
RECIPROCAT1NG-PISTON COMPRESSOR (PLANTS
PRODUCING LEAD MONOXIDE)
PARAMETER
PH
TDS
TSS
Oil and Grease
Cr (total)
Cd
Cu
Pb
Hg
Zn
CONCENTRATION
img/li*
6.4*
560
780
1,960*«
0.85
<0.01
0.48
<0.02
< 0.0002
0,34
•Contractor sample collection and analysis (one 24-hour
composite collected 13 December 1976).
tValue in pH units.
*'Contract or sample collection and analysis (four grab
samples collected 13 December 1976),
103
-------
piston design, although there are oil-free or dry-type
reciproeating-piston compressors which utilize graphite or
teflon piston rings for lubrication in low-pressure service.
Centrifugal compressors and mercury-piston compressors are
other examples of dry-type compressors. These oil-free
compressors also produce condensate1, but the condensate does
not contact any oil-lubricated surfaces and, therefore, does
not contain appreciable concentrations of oil and grease.
Compressor blowdown from oil-free compressors is essentially
clean water.
Noncoivtact Coolirig ' Water. Eleven lead monoxide
manufacturers employ noncontact cooling water to rapidly
cool lead monoxide as it exits the furnace, thereby
preventing the formation of red lead. Contamination does
not occurf because the pressure gradient is from the water
to the product, and the material solidifies on cooling. The
result is that the noncontact cooling water is compatible
with PQTW operation.
PROCESS-WASTE CHARACTERIZATION FOR NICKEL SULFATE
SUBCATEGORY
process Description and Water Use
Nickel sulfate is produced from two types of raw materials:
(1) pure nickel or nickel oxide
(2) impure nickel-containing materials—e.g., spent nickel
catalysts or nickel carbonate made by addition of soda
ash (sodium carbonate) to spent nickel-plating
solutions.
In the first case, the metal or oxide is digested in
sulfuric acid to produce a nickel sulfate solution. The
solution is filtered and either packaged for sale or further
processed to recover a solid material, nickel sulfate
hexahydrate. Water and/or sodium hydroxide may be added to
the solution prior to packaging to achieve the desired
specifications.
Plant 19801, which discharges waste water ^o a PQTW, employs
this process to produce a 60% nickel sulfate solution. A
process flow diagram, detailing water use at Plant 19801r is
presented in Figure 32.
water is consumed in the process to achieve the desired
nickel sulfate solution. A wet scrubber is employed to
clean fumes and dust from the work area. Scrubber water is
recycled, with only a small bleed (10%) actually being
104
-------
o
en
Figure 32. FLOW DIAGRAM FOR PRODUCTION OF NICKEL SULFATE (PLANT 19801)
WATER
CLEAN
GASES
SCRUBBER
WASHWATER
SCRUBBER
•WATER
RECYCLE
SCRUBBER
WATER
HOLDING
TANK
PROCESS
FUMES
AND
DUST
3ULFURIC
ACID
NICKEL
OXIDE
OVERFLOW
i
| HYDROXIDE!
TT T t I
REACTOR
FILTER
HOLDING
TANK
FLOOR & EQUIP
WASHINGS
I
FILTER WASHWATER
NICKEL
SULFATE
SOLUTION
PACKAGING
TO PRfTREATMENT
t
TO SALES
-------
discharged. Additional water is used intermittently for
scrubber washdown, filter-press washing, and floor washing.
Noncontact cooling water is used to cool the reactor.
The second process uses impure nickel-containing compounds
as raw material, instead of pure nickel metal or oxide. The
raw materials are digested with sulfuric acid to produce a
nickel sulfate solution. The resulting solution must be
treated in series with oxidizers, lime, and sulfides to
precipitate impurities. The solution is filtered and
marketed or further processed to recover the solid
hexahydrate.
To recover solid product, the nickel sulfate solutions are
first concentrated, filtered, and fed to a cryatallizer.
The resulting suspensions are fed to a classifier, where
solid product is recovered. This material is then dried,
cooled, screened, and packaged for sale. The recovered
solids from the filtration step and the mother liquor from
the classifiers are recycled back to the beginning of the
process.
A process flow sheet, detailing nickel sulfate production
(at Plant 19803) from impure nickel-containing compounds, is
presented as Figure 33.
Water use includes:
(1) process water used in making the nickel sulfate
solution
(2) barometric-condenser water
(3) filter-backwash water
(4) noncontact reactor-cooling water and cooling-tower
blowdown.
Sources of Wastewater
Wastewater generated during nickel sulfate production at
Plant 19801 includes;
Scrubber Bleed water. Fumes and dust in the work area are
collected by a fan and directed to a wet scrubber.
Approximately 6.8 cubic meters (1,800 gallons) of city water
are used daily to clean the fumes. The scrubber water is
collected in a baffled tank to facilitate settling of
suspended solids and then recycled. About 0.68 cubic meter
(180 gallons) overflows the tank daily and is discharged
after pretreatment. The scrubber is in operation at all
times during a production run (4 to 8 hours).
106
-------
Figure 33. FLOW DIAGRAM FOR PRODUCTION OF NICKEL SULFATE
(PLANT 19803)
NICKEL
POWOiR ~
NICKEL-*.
OXIDE
DIGESTOR
•«~STEAM
-SULFURIC
ACID
orcesTOR
-SPENT PLATING SOLUTION
-SODIUM CARBONATE
SOLUTION •
PRODUCT
FILTER
SPENT NICKEL
CATALYST*
STEAM -
SULFURIC '
ACID
FILTER
DIGESTOR
,-. SPENT NICKEL „,_. (PNT
^*^ nrairuirr EFFLUENT
QUALITY-
CONTROL
LABORATORY
RESIDUES
AIRH
TREATING TANK
FILTER
-SULFURIC ACID
-OXtDiZER
•^-CALCIUM
CARBONATE
-SLUDGE
LIME*-
SULFIDE^
- LIQUOR-
TREATING TANK
FILTER
•SLUDGE
CONCENTRATOR
STEAM
FlLTiR
EVAPORATION TANK
CRYSTALLIZES
COOtING
WATER
CLASSIFIER
( STEAM
"I
HOLDING TANK
DRYER
—DUSTS
"U
COOLING, SCREENING,
AND PACKAGING
—DUSTS
SCRUBBER
-WATER
SOLID PRODUCT
TO SALES
SOURCE: REFERENCES
107
-------
ggrubber Washdgwn Water, After each production run, the
scrubber is washed down with 0.08 cubic meter (20 gallons)
of water to remove scale.
Filter Wash Water. After the nickel sulfate solution has
been filtered, the filter press is disassembled and the
filter sheets hosed off to remove caked material. The
amount of water used ranges from 0.09 to 0.28 cubic meter
(25 to 75 gallons) per washing.
Floor Washings. Periodically* during production, the
equipment and floor area are washed to remove spilled raw
materials and product. Flow from this operation can vary
from 0.02 to 0.09 cubic meter (5 to 25 gallons) per
operating day.
Daily total waste water generation at Plant 19801 is 1 cubic
meter (300 gallons).
Wastewater generation at Plant 19803 includes:
Filtrates. Spent plating solutions are digested and treated
with soda ash. The resulting solution is filtered and the
solids sent for further processing. Approjcimately 20 cubic
meters (5,000 gallons) of waste filtrate are generated daily
from this operation.
Filter Sludges. During production of both aqueous and
crystalline nickel sulfate, the nickel sulfate is directed
to several filtration steps. (See Figure 33.) The filters
must be cleaned periodically to remove caked material.
Depending on the techniques employed to clean the filters
and the amount of washwater used, the resultant sludges pose
either a waste water or a solid-waste problem. At Plant
19803, the latter is true. However, the potential for waste
water generation similar to that encountered at Plant 19801
should be considered,
Wastewater characteristics
The chemical characteristics of the combined waste water
from three nickel sulfate plants are presented in Table 14.
Plants 19801 and 19802 both use nickel oxide as a raw
material, and both are POTW dischargers. Plant 19803 uses
impure nickel-bearing materials to produce nickel sulfate.
Although it is a direct discharger, Plant 19803 can be
considered representative of a POTW discharger employing a
similar process.
Table 15 presents the chemical characteristics of each
separate wastewater stream emanating from Plant 19801. The
108
-------
TABLE 14. CHEMICAL COMPOSITIONS OF RAW WASTEWATERS FROM
PRODUCTION OF NICKEL SULFATE (THREE PLANTS)
PARAMETER
pM
IDS
TSS
Cr (total)
Cu
Ni
Suifata
CONCENTRATION (m^I)
PLANT 19801
9.1*
24,100
525
0.16
5.0
360
228
PLANT 19802
8.5*
2,100
240
0.007
68
140
153
PLANT 19803
8.2»
-
—
—
—
12
-
"Value in pH units.
109
-------
TABLE 15. CHEMICAL COMPOSITIONS OF INDIVIDUAL PROCESS WASTE STREAMS
FROM PRODUCTION OF NICKEL SULFATE (PLANT 19801)
PARAMETER
pH
TDS
TSS
Cr {total)
Cu
Ni
Sulf«tt
CONCENTRATION img/I)
SCRUBBER BLEED
i.«*
32,000
98
0,10
1.0
32
260
SCRUBBER WASHDOWN
4.8*
18,000
210
0,22
16
2,200
160
FILTER WASHINGS
6,i«
7,200
1,700
0,34
2,4
920
1i3
FLOOR WASHINGS
7.0*
4,600
1,900
0,29
35
440
195
'Value in pH units.
no
-------
most significant pollutant present is nickel. Other
parameters, such as pH, TSS, TDS, zinc, and copper,
occasionally appear in high concentrations.
Most of the heavy metals in the scrubber water-are settled
out in the holding tank prior to recycle. The dissolved
salts, however, are not removed to any great extent;
instead, they are concentrated. As a result, the scrubber
water exhibits relatively low metal levels, while dissolved-
solids levels are high. In the case of the washdown waters,
small volumes of water are brough into contact with almost
pure raw materials, products, and miscellaneous plant dusts,
resulting in high suspended-solids and metal concentrations.
PROCESS-WASTE CHARACTERIZATION FOR NITROGEN AND OXYGEN
SUBCATEGORY
Process Description and Water Use
In the process of air separation, the major use of water is
for noncontact cooling. This water is usually on a single-
pass basis, although some plants may recycle a limited
volume. Frequently, the stream is characterized by varying
concentrations of chromium and/or zinc, which are added as
corrosion inhibitors. Noncontact cooling water, after
passing through the plant cooling towers, is discharged
without further treatment.
The moisture which is trapped in the compressors forms as a
result of the condensation of the water-vapor portion of the
incoming atmospheric air. The volume of this compressor
condensate is characteristically small, although, when it
contacts the lubricating oil of the compressor cylinders, an
oily waste water is formed which periodically requires some
pretreatment before discharge.
Another process waste stream which is generated in some air-
separation plants is caustic-scrubber solution. This is
found in those plants which use caustic to remove carbon
dioxide impurities from the filtered air prior to
separation. Again, resulting waste water volumes are
limited, and the usual practice is to totally impound this
waste stream and have it removed from the plant.
Sources of Wastewater
The sources of process waste water in the production of
nitrogen and oxygen via air separation are:
compressor condensate
caustic-scrubber solution
111
-------
noncontact cooling water (cooling-tower blowdown)
See Figure 3H.
The contact process waters of particular interest in the
production of nitrogen and oxygen are compressor eondensate
and caustic-scrubber solution, Condensate results from the
compression of the water-vapor portion of atmospheric air as
it undergoes the effect of high pressure. In the older-type
reciprocating compressors, lubricating oil is required in
the cylinder chambers to minimize frictional effects. This
oil becomes mixed with water-vapor condensate in the
compressor and results in the generation of a process waste
water. The compressors are blown down periodically, and the
oily condensate is collected and added to a common sump area
with plant-floor washings and any leaks and spills which
have been collected from throughout the plant. Data
available on the amount of actual compressor condensate
generated in any particular plant are extremely limited.
The known production volumes, which usually represent a
total of combined oily wastes, are characteristically small,
ranging from as little as the 0.011 I/metric ton (0.022
gal/short ton) produced at Plant 13103 to a maximum of 42.8
I/metric ton (85.6 gal/short ton) at Plant 13101, with an
average of approximately 1.4 I/metric ton (2.8 gal/short
ton).
The other process waste stream mentioned (i.e., caustic-
scrubber solution) is not common to many air-separation
plants. The waste water is generated in the process of
carbon dioxide removal, which is necessary to purify the air
prior to separation, in those plants where this process is
employed, it is common practice to totally impound the waste
water produced so that it in no way adds to the total waste
stream. No data on the waste characterization or flow of
this stream are currently available.
Equipment and plant washdowns are accomplished with minimal
waste water production, in air-separation plants, washdown
streams are commonly characterized by the presence of some
oil and grease from compressor crankcases, but no data are
available on the actual concentration of this additive.
Leaks and spills are infrequent occurrences and are of no
real significance to the total waste production. Plant
13102 indicates that only one minor leak of approximate 38
I/day (10 gal/day) of crankcase oil occurred within one full
year of operation.
Wastewater gha_rac_teriatics
Table 16 gives a summary of the raw waste characteristics of
a compressor-condensate stream. Since adequate raw data
112
-------
Figure 34. FLOW DIAGRAM SHOWING GENERALIZED WASTEWATER FLOWS IN
PRODUCTION OF NITROGEN AND OXYGEN
FILTERED
ATMOSPHERIC
AIR
FLOOR LEAKS
ORA1NS AND SPILLS
— COMPENSATE-
COLLECTION
SUMP
OIL
SEPARATOR
!
COOLING WATER
COMPRESSED
AIR
CAUSTIC
SCRUBBER
LIQUIFIES/
HICT1WEB
COLUMN
LIQUID LIQUID
OXYGEN NITROGEN
JL i
Olt
TO WASTf
TREATED
EFFLUENT
-SLOWDOWN-
I
FINAL
EFFLUENT
DISCHARGE
- SODIUM HYDfiOX JOE
-WATER
scttmmn SOLUTION
TO SALES
113
-------
TABLE 16. CHEMICAL COMPOSITION OF WASTE LOADING FOR UNTREATED
COMPRESSOR-CONDENSATE STREAM FROM PRODUCTION OF
NITROGEN AND OXYGEN (PLANT 13101)
PARAMETER
PH
TDS
TSS
Ott and Qreisa
Cd
Cr (total)
Cu
Pb
Ha
Zn
CONCENTRATION "
6.4*
560
780
1,960
<0.01
0.85
0.48
<0.02
<0.0002
0.34
WASTE LOAD
kg/1000 metric tons
_
24
33
84
< 0.00,043
0.036
0.020
< 0.00086
< 0.00001
0.016
lb/1 000 thoit torn
_
48
86
170
< 0.00086
0.072
0.041
<0,0017
<0.00002
0.030
* Analysis bated on composite of four individual grab samples taken over 8-hour period.
* Value in pH units.
114
-------
characterizing this process waste stream have not been
readily available from the industry, particular emphasis is
placed on the data given in this table, which represent
actual waste water samples taken during a plant visit. The
data reflect the composition of a eompressor-condensate
stream produced in an air-separation plant employing
reciprocating compressors. The samples were taken under
normal plant operating conditions.
Most data available from the industry characterize only the
effluent stream of compressor condensate after it has passed
through some oil removal system; frequently, the stream has
been highly diluted by its combination with large volumes of
noncontact cooling water prior to discharge. Since the
condensate stream itself is of particular interest, because
it contacts the process, the combined effluent data have
limited value in the waste characterization of this
individual stream.
PROCESS-WASTE CHARACTERIZATION FOR POTASSIUM DICHROMATE
SUBCATEGORY
General
At present, a single plant (Plant 19901) is known to
manufacture potassium dichromate. Water use and waste water
sources at this plant are described in this section.
However, it must be noted that this plant does not presently
discharge process-related waste water to a POTW.
Process Description and Water Use
Potassium dichromate is prepared by reaction of potassium
chloride with sodium dichromate. Potassium chloride is
added to the dichromate solution, which is then pH-adjusted,
saturated, filtered, and vacuum-cooled to precipitate
crystalline potassium dichromate. The product is recovered
by centrifugation, dried, sized, and packaged. The mother
liquor from the product centrifuge is then concentrated to
precipitate sodium chloride, which is removed as a solid
waste from a salt centrifuge. The process liquid is
recycled back to the initial reaction tank.
Water is used directly in the production process as the
medium in which the raw materials are mixed and reacted.
Water is also used for noncontact cooling in the vacuum-
crystallization step of the process. (See Figure 15.)
Sources of wastewater
115
-------
All water used directly in the process at Plant 19901 is
either consumed by evaporation or recycled. Water used for
noneontaet cooling during the vacuum-crystallization step is
discharged. In the past, the use of barometric condensers
as the cooling apparatus allowed contamination of the
cooling water by chromium from the process. As a result,
cooling water discharges from Plant 19901 have contained as
much as 249 mg/1 of chromium. However, completion of recent
pollution-control projects, including the replacement of the
barometric condensers with heat exchangers to provide only
noncontact cooling, have reportedly eliminated the
contamination of cooling water.
Solid wastes generated by this process include the
crystalline sodium chloride and filter aids. These are
hauled away for landfill disposal by a contractor.
Wastewater Characteristics
No waste water is discharged directly from the process at
Plant 19901. Approximately 245 cubic meters (65,000
gallons) of water are added daily as makeup to the process,
and this is subquently consumed by evaporation in the
process. The volume of cooling water used daily is 1,325
cubic meters (350,000 gallons).
PROCESS-WASTE CHARACTERIZATION FOR POTASSIUM IODIDE
SUSCATEGORY
General
The character of waste water generated in this industry
subcategory is determined largely by the source of the
discharge and the use made of this water prior to discharge.
The characteristics of the raw wastewater and the volume of
discharge are significant factors to the extent that they
effectively determine both the treatment alternatives avail-
able and the cost of treatment. Water usage, the source and
character of the waste waters generated, and the volumes of
waste water generated-typical for this industry subcategory-
-are identified and discussed below.
Process Description and Hater gge
Plant 20102, which is located on the East Coast, produces an
average of 57 metric tons (63 short tons) of potassium
iodide per annum. The manufacturing process employed has
been schematically presented in Figure 16 and is Jcnown as
the iron carbonate process. This process involves the
reaction of iron powder with iodine in aqueous solution. An
intermediate compound, ferrosoferriciodide, is formed which
116
-------
is subsequently reacted with potassium carbonate to yield
potassium iodide. Small amounts of barium hydroxide and
potassium sulfide are added to precipitate any trace sulfate
or heavy-metal impurities present. Following this
purification step, the potassium iodide solution is
concentrated by evaporation and cooled to effect
crystallization. The crystals are separated by
centrifugation, dried, sifted, and packaged. Residual
mother liquor collected during centrifugation is recycled to
the evaporator.
As indicated in Figure 16, water used directly in the
process provides the necessary medium in which the
production reaction is effected. As discussed in section
III, the purification steps, if any, of a process are also
necessarily carried out in an aqueous medium. A second
process related use of water is for noncontact cooling
during the crystallization step. Three of the four plants
which presently manufacture potassium iodide use water in
this capacity. Another use of water is as boiler "feed
water. Finally, at all plants in this industry, a small
quantity of water is used for equipment and production area
washdown and cleanup of spills.
sources of Wastewater
At each of the four plants engaged in the manufacture of
potassium iodide, water used directly in the process is not
discharged; rather, it is lost from the process by
evaporation. This loss is purposely initiated during the
fusing and evaporation steps of the iodine/potassium
hydroxide and iron carbonate processes, respectively. At
three of the plants, solid-waste slurries and purification
sludges from the process are handled as such and are either
removed by a commercial solid-waste contractor or sent to a
land fill. At the remaining plant, the purification sludges
and process-associated waste water are discharged without
treatment to a PQTW.
The primary source of process waste water in this industry
is that water which is used for equipment and production-
area washdown and cleanup of product or reagent spills.
Water used for noncontact cooling is also discharged.
However, with the exception of temperature, the character of
this water remains essentially unchanged while it is being
used.
Wastewater character iattjLcs
Substances which can be expected to occur at elevated
concentration in the waste water are the raw materials and
117
-------
products associated with the production process.. These
materials and products are total suspended solids, total
dissolved solids, barium, iron, sulfide, potassium iodide,
potassium iodate and iodine.
The volumes of waste water discharged vary from plant to
plant. Wastewater resulting from equipment washdowns and
cleanup of spills averages 0.15 to 1.11 cubic meters (39 to
300 gallons) daily. water used for noncontact cooling
averages 5.90 to 32,6 cubic meters (1,560 to 8,600 gallons)
daily. Water is not used for cooling purposes at one plant
in this industry. One of the three plants which does use
water for cooling recycles 100% of this water.
PROCESS-WASTE CHARACTERIZATIOM FOR SILVER NITRATE
SDBCRTEGORY
general
There are three significant plants known to be producing
silver nitrate in the U.S. None of these plants discharge
process waste water to a POTW. ,However, it is anticipated
that a silver nitrate producer discharging to a POTW would
be similar in nature to a silver nitrate producer with a
direct discharge.
Processes employed in silver nitrate production are basic to
the entire industry. It is unlikely that an indirect
discharger would implement a radically new process. of
course, water use will vary from plant to plant. However,
the economics achieved by recycling and recovering silver-
bearing wastes provide a great impetus to reduce waste water
generation. This impetus is present irrespective of the
mode of discharge. In light of the above, information on
silver nitrate producers discharging process waste water
directly to surface waters is next used to describe that
portion of the silver nitrate sabcategory discharging to
POTWS,
Process. Description and Water use
At Plant 20201, pure silver is dissolved in distilled nitric
acid, and the resulting solution is fed to a steam-heated
evaporator. The NQx gases from the dissolver are mixed with
air and recycled "evaporator condensate and converted to
nitrogen dioxide, which is used to remake nitric acid for
the process. The tail gases from the nitric acid recovery
unit are scrubbed with a caustic solution prior to venting
to the atmosphere. The concentrated mother liquor from the
evaporator is sent to a crystallizer, and the crystals
formed are centrifuged and washed with demlneralized water.
118
-------
The mother liquor and wash water from the centrifuge are
recycled to the evaporator after treatment to remove heavy-
metal impurities. The silver nitrate crystals from the
centrifuge are redissolved in low-pressure steam,
recrystallized, recentrifuged, rewashed, dried, and
packaged. The mother liquor from the second crystallizer is
sent to another steam-heated evaporator for concentration
and recycled to both crystallizers. Simplified process
chemical reactions are:
Ag + 2HNO3 = AgNO3 •«• NO2 + H2O
3Ag + 1HNO3_ » 3AgNO3 + NO + 2H2O.
The process at Plant 20201 is shown in Figure 35.
The process used at Plant 20202 is the same as that
described above with the exception that extensive use is
made of stream recycling, as can be seen from the diagram in
Figure 36.
Water use at Plant 20201 includes:
(1) Centrifuge wash water
(2) Water for redissolution of crystals
(3) Caustic-scrubber solution of NOx
emissions control
(4) Floor and equipment washings
(5) Noncontact cooling water is used in the
nitric acid recovery unit, the crystallizers,
and the evaporators.
Water use at Plant 20202 is similar to that at Plant 20201.
However, Plant 20202 uses clean water in its nitric acid
recovery unit rather than recycled evaporator condensate.
Sources of Wastewater
Evaporator Condensate. A waste condensate is generated from
the barometric condensers .used in the manufacture of
supersaturated solutions for the crystallizers. At Plant
20201, part of the condensate from the second evaporation
step are recycled to the nitric acid recovery unit. The
remaining condensate, about 1,5 cubic meters (400 gallons)
each day, is combined with the emissions-control scrubber
water, 0.38 cubic meter (100 gallons) daily, and directed to
the silver-recovery process.
Centrifuge Wash Water. Wastewater generated during
centrifugation of crystals is directed to the chemical-
purification unit for metal removal.
119
-------
Figure 35. FLOW DIAGRAM FOR PRODUCTION OF SILVER NITRATE
(PLANT 20201)
CAUSTIC
SOLUTION
SCRUBBER
SPENT
• SCRUBBER-
SOLUTION
AIR-
NITRIC ACID-
SILVER-
NITRIC ACID
RECOVERY
WASH
WATER"
WATER-
STEAM-
EVAPORATOR
I
CONDENSATE
i
WATER"
TAIL GASES
I
REACTOR
EVAPORATOR
-CONDENSATE
CYRSTALLIZER
CENTRIFUGE
REDISSOLVER
I
CRYSTALLIZER
I
CENTRIFUGE
DRYER
PRODUCT
PACKAGING
T
TO SALES
CAUSTIC
SOLUTION
i
CHEMICAL
PURIFICATION
SILVER
RECOVERY
DISCHARGE
VENT
1
BAG FILTER
\
SOLID
WASTE
,
SILVER
TO SALES
120
-------
Figure 36. FLOW DIAGRAM FOR PRODUCTION OF SILVER NITRATE (PLANT 20202)
WATER-
NITRIC
ACID-
WATER.
SILVER
OXYGEN
SOLIDS
ABSORBER
MtXER
REACTOR
AUXILIARY REACTOR
FILTER
TAIL
SILVER
OXIDE"
CHEMICAL TREATMENT
WASH.
WATER
(=ILTII?
ALUMINA COLUMN
EVAPORATOR
CRYSTALUZSR
CENTRIFUGE
SOLID
'WASTE
.TO
RECOVERY
WATER ..- »•
WASH k.
WATER
REDISSOLVE TANK
1
FILTER
'
'
CRYSTALUZEH
I
CENTS
I
'
IFUGE
f
DRYER
PRODUCT
PACKAGING
t
.SOLID
WASTE
•VENT
TO SALES
SOURCE: REFERENCE 5
121
-------
Chemical-Purification Wastewater- Solution from the initial
crystallization step is treated with sodium hydroxide to
remove metals. The resultant waste stream is sent to the
silver-recovery process at both plants.
Floor and Equipment Washing**. At Plant 20201, equipment and
work areas are periodically washed with 2.6 cubic meters
(700 gallons) of water each day. This wash water is
directed to the silver-recovery process.
NOX Ejmis si on s- Control Scrubber Water. A caustic solution is
used to remove NOx emissions from the nitric acid recovery
unit at Plant 20201. The scrubber waste water is directed
to a separate part of the plant for silver recovery. The
gaseous NOx products from the reactor in Plant 20202 are
entirely reconverted to nitric acid, which is recycled.
This eliminates the need for a gas scrubber and the
resultant nitrate-bearing scrubber wastes,
S.J Ivgr - Reg oy er y Wastewater. The emissions-control scrubber
water, evaporator condensate, chemical-purification waste
water, and washdowns are sent to the silver-recovery
process, where 99+% of the silver is removed. The remaining
waste water is discharged to the industrial treatment
system.
Waatewater Character istics '
The waste water associated with silver nitrate production
may contain as much as 5 mg/1 silver, after processing at
the silver-recovery plant. Because waste water streams from
many production operations are combined, the presence and
levels of trace metals in silver nitrate process waste water
are unknown. However, the use of relatively pure raw
material and the active removal of metallic impurities
within the process prevent the introduction of significant
quantities of metallic pollutants in the waste water.
PROCESS-WASTE CHARACTERIZATION FOR SODIUM BICARBONATE
SUBCATEGORY '
Process Description and water Use
Sodium bicarbonate is manufactured by the carbonation of a
sodium carbonate solution. Plants 12101 and 12102 are
located within complexes manufacturing soda ash (sodium
carbonate) by the Solvay process. Figure 37 illustrates the
solvay sodium bicarbonate process. There is one facility,
Plant 12103, which uses mined soda ash as a raw material.
122
-------
Figure 37. FLOW DIAGRAM OF SOLVAY PROCESS FOR PRODUCTION OF
SODIUM BICARBONATE (PLANT 12101)
SODIUM
CARBONATE
RECYCLE-LIQUOH
OVERFLOW
SODIUM
SESOUICARBONATE
FEED
TO
WASTE
SODIUM
SESQUICARBONATE
PURGE
BACK WASH
(SODIUM
SUSQUICARBONATE
PURGE)
CARBON
DIOXIDE
(40%)
MILL COOLING
WATER
TO SALES
123
-------
Water usage data for Plant 12101 are shown below. Most of
the water is used for noncontact cooling purposes.
TYPE OF WATER m3/day (mgd) I/metric ton RECYCLED
(cral/short ton)
Cooling l,t3Q (0.378) 5,430 (1,300) None
Process 119 (0.031) «55 (109) Variable
Process water includes dissolution water . used in the
reaction, Scrubber water from drier emissions control,
filter-backwash water, and miscellaneous washdown waters. A
process flow diagram indicating water use at Plant 12101 is
given as Figure 37.
Sources of Wastewater
The sources of waste water at Plant 12101 are;
Recycle liquor
Filter backwash
Noncontact cooling water
Spills, leaks, and washdowns
Compressor blowdown
These operations are also expected to be the primary sources
of wastewater at other sodium bicarbonate plants, since
standard manufacturing processes are employed.
Wastewater Characteristics
-Li guor Over flow, slurry thickener overflow and
dryer emissions control scrubber water are combined and
directed to a recycle- liquor storage tank. Under normal
flow conditions, this recycle liquor is returned to the soda
ash dissolver to be reused in the process. Excess recycle
liquor is directed to other manufacturing processes within
the plant complex. Occasionally, the amount of recycle
liquor generated exceeds the requirements of both the soda
ash dissolver operation and the other miscellaneous plant
operations utilizing this byproduct. Onder these
conditions, a recycle-liquor overflow is generated which is
discharged to the plant complex treatment system.
On a yearly basis, this waste water flow averages 75.7 cubic
meters (20,000 gallons) each day.
The major wastes produced from the manufacture of sodium
bicarbonate result from this operation. Recycle-liquor
overflow contains about 10 kg (22 lb) of undissolved sodium
-------
bicarbonate per metric ton (1.1 short tons) of product and
an average of about 38 kg (8* Ib) of dissolved sodium
carbonate per metric ton (1.1 short tons) of product. The
chemical character of recycle-liquor overflow is shown in
Table 17.
Filter Backwash. Sand and/or pressure-leaf filters may be
used in the sodium bicarbonate manufacturing process to
purify the dissolved soda ash input to the carbonating
columns. Plant 12101 uses both sand and pressure-leaf
filters in series to remove suspended solids from the
dissolved soda ash liquor prior to carbonation. It is
necessary to periodically backwash these filters to prevent
clogging of the filters, with resulting head loss and slow
filtration rates.
The volume of filter backwash is highly variable but is
typically only 2 to SSI of the plant throughput (Reference
9). The chemical characteristics of filter backwash are
also highly variable. Sufficient data were not available to
characterize this process waste water, but filter backwash
is by nature expected to contain high levels of suspended
solids. Dissolved solids may also be present in significant
quantities, depending upon the extent that dissolved soda
ash liquor, which is high in dissolved solids, is retained
in the filter cake, and on the initial dissolved-solids
concentration of the filter-backwash water.
Noncontact Cooling Water. Noncontact cooling water is
employed in the manufacture of sodium bicarbonate- to
maintain a temperature of about H0°c (104°F) in the
carbonation columns. There are no chemical data available
relative to noncontact cooling water. However, it may be
assumed that its composition is at least compatible with
POTW operation, because the source of noncontact cooling
water is a lake, and this water has no direct contact with
the product.
Leaks^ Spills^ and Washdown Waterwater. Wastewater
emanating from leaks, spills, and facility washdowns (i.e.,
hosing, mopping, etc.) may contain high levels of sodium
bicarbonate product as suspended solids and would,
therefore, merit consideration as process waste waters.
However, large leaks and spills are not common to the
industry, for two reasons. First, the materials used in the
process are neither highly acidic or highly basic, and
corrosion of pipes, fittings, and other hardware is not a
problem. Secondly, a large portion of sodium bicarbonate
production is food-grade product, and good housekeeping
procedures for such facilities are a must.
125
-------
TABLE 17. ESTIMATED CHEMICAL CHARACTERISTICS OF UNTREATED SLURRY
THICKENER OVERFLOW FROM PRODUCTION OF SODIUM BICARBONATE
(PLANT 12101}
PARAMETER
pH
TDS
TSS
CONCENTRATION (ma/I)*
7.6108,2*
136,800
36,000
'Calculated from waste loadings and wastewatar flow data.
'Value in pH units.
126
-------
Compressor Slowdown. Compressors may be used in the
manufacture of sodium bicarbonate to inject carbon dioxide
into the bottom of the carbonating columns. Compressed
carbon dioxide is a raw material in the sodium bicarbonate
manufacturing process, and, since compressor condensate
directly contacts this raw material, it may be considered a
process waste water. Carbon dioxide may be purchased for
use in this process, thus eliminating the source of this
waste water.
Chemical characteristics of compressor blowdown are
extremely variable, being dependant upon the water-vapor
content of the carbon dioxide gas and on compressor design
and age. pollutants from this source are carbon dioxide and
oil and grease.
PROCESS-WASTE CHARACTERI2ATION FOR SODIUM FLUORIDE
SUBCATEGORY .
Process Description and Water Use
Sodium fluoride is produced from three different processes:
(1) Reaction of soda ash (sodium carbonate) with hydro-
fluoric acid.
(2) Reaction of caustic soda {sodium hydroxide) with
sodium silico-fluoride.
(3) Reaction of caustic soda with hydrofluoric acid.
In the first process listed, anhydrous hydrofluoric acid
(hydrogen fluoride) and soda ash are reacted, and hydrogen
fluoride fumes and carbon dioxide are scrubbed with a soda
ash solution. The product from the reactor is a slurry of
sodium fluoride, which is vacuum-filtered to recover the
fluoride. The product is then dried and packaged. The
overall process reaction is;
2HF + N3.2CO3 = 2NaF + H2O * CO2
Plant 20301 employs this process, with no resulting
discharge of process waste water. A process diagram
detailing water use at Plant 20301 is presented in Figure
38. Total water consumption at Plant 20301 averages 2,300
liters of municipal water per metric ton (550 gallons per
short ton) of sodium fluoride product. This is used
primarily for boiler feed, with a small amount used as
makeup water in the scrubber.
The second process is used at Plant 20302 and is illustrated
in Figure 39. At Plant 20302, sodium silicofluoride is
reacted with a solution of caustic soda and water in a batch
127
-------
Figure 38. FLOW DIAGRAM FOR PRODUCTION OF SODIUM FLUORIDE
(PLANT 20301}
ANHYDROUS HYDROFLUORIC ACID-
SODIUM CARBONATE-
RECYCLE
MOTHER-LIQUOR
HOLDING TANK
-LIQUOR-
DRY SODIUM FLUORIDE
(PROM PRODUCT STREAM)
STEAM <
SODIUM
CARBONATE
STIRRED
R1ACTOR
GASES
(HYDROFLUORIC ACID*»
AND CAR BON DIOXIDE)
• RECYCLE-
WATER
RECYCLE
WET
SCRUBBER
J
1
VACUUM
CRYSTALLIZE H
I
SURGE TANK
VACUUM
FILTER
I
SOLIDS
i
T
TO SALES
(USED IN
SODIUM
B1FLUORIDE
PRODUCTION
ONLY)
E - ^
« ^
PLUG
MIXER
I
'
DRYER
1
*
-^
1*
PRODUCT
STORAGE
AND
PACKAGING
»-
DRY
DUST COLLECTOR
128
-------
Figure 39. FLOW DIAGRAM FOR PRODUCTION OF SODIUM FLUORIDE (PLANT 20302)
WASH
WATER
ro
to
50%
CAUSTIC
SODIUM
SILICOFLUORIDE
WATER
_L
WATER
T— RECYCLE
BATCH
REACTOR
~~J
ATER VENT
i_ t
SEPARATOR
DRYER
WATER
RECYCLE
BATCH SCRUBBER
"SLOWDOWN
u
PRODUCT
PACKAGING
TO
'SALES
WET
SCRUBBER
WASTE
WATER
SOURCE: REFERENCES
-------
reactor. The product, a mixture of sodium fluoride, sodium
silicate, and water, is sent to a multi-stage separator,
where the sodium fluoride is separated from the soluble
sodium silicate. The sodium fluoride product is washed,
dried, and collected in a dry cyclpne for packaging. The
wash water from the separator is recycled to the reactor,
soluble sodium silicate and sodium fluoride in an alkaline
solution constitutes the byproduct waste stream from this
process. A recycle wet scrubber, used to remove sodium
fluoride dusts from the vent on thei dry collector, is blown
down to the silicate waste effluent. The reaction for the
process is:
6NaOH + Na2SiFi * 6NaP + Na.2Si03 + 3HK>
Total water consumption at Plant 20302 averages 3,860 liters
per metric ton (925 gallons per short ton) of sodium
fluoride product. This water is used for dilution of the
caustic soda, washing the product, and wet scrubbing. No
cooling water or steam is used in the process. In addition,
the process reaction produces 217 liters of water per metric
ton (52 gallons per short ton) of product. Untreated waste
water data from the plant is shown in Table 18.
The third process is very similar in principle to the second
process just discussed. Both processes involve a batch
reaction in aqueous solution, producing a sodium fluoride
precipitate which is separated from solution, dried, and
packaged for sale. The fundamental difference between the
two processes is in the separation operation. The second
process utilizes a multiple-stage separator to selectively
remove sodium fluoride from the solution, which also
contains sodium silicate. This third process employs a
less-complex separation using a settling tank, since the
reaction precipitate does not contain a substantial amount
of impurities. The reaction for the process is:
NaOH + HP + H2O = NaP + 2H2O
Plant 20303 employs this process, with the resulting waste
water produced discharged directly. Figure 40 illustrates
the sodium fluoride manufacturing process and water uses at
Plant 20303.
Total water consumption at Plant 20303 averages 23,185
liters per metric ton (5,610 gallons per short ton) of
sodium fluoride product. This water is used for dilution of
the caustic soda, for washdown, and for noncontact cooling
of the batch reactor. The process reaction produces 434
liters of water per metric ton (104 gallons per short ton)
of sodium fluoride, but this water is not recycled and.
130
-------
TABLE 18. CHEMICAL COMPOSITION OF UNTREATED WASTEWATER FROM
PRODUCTION OF SODIUM FLUORIDE (PLANT 20302)
PARAMETER
pH
TDS
TSS
Fluoride
CONCENTRATION
(ma/i)»
>12*»
165,000
2,500
16,000
•Company monitoring data (Sample collected 28
November 1973).
•'Value in pH units.
131
-------
Figure 40. FLOW DIAGRAM FOR PRODUCTION OF SODIUM FLUORIDE (PLANT 20303)
WELL WATER
{FOR NONCONTACT COOLING!
1
co
i\s
HYDROFLUORIC ACID'
DEIONIZED WATER-
50% CAUSTIC-
BATCH
REACTOR
SETTLING
TANK
NONCONTACT
COOLING WATER
PROCESS WASTE
SOLUTION
WASTEWATER
VENT
CONCENTRATOR
PACKAGING
PRODUCT
•TO
SALES
-------
therefore, has no effect on the consumption of water at
Plant 20303. Table 19 compares water use at this plant to
those of plants using other sodium fluoride manufacturing
processes.
Sources of wastewater
Process waste water generated during sodium fluoride
production at Plant 20301 consists of filtrate mother
liquors, washdown waters, and wetscrubber water. All of
these wastes are recycled, resulting in no discharge of
process waste water from this plant.
Process wastes at Plant 20302 consist of separated silicate
liquors containing soluble sodium fluoride, wet-scrubber
blowdown, product wash water, and product dusts from the
packaging operation. The product dusts and product wash
water are recycled to the reactor. The other wastes amount
to 1,995 liters per metric ton (^78 gallons per short ton)
of sodium fluoride product and are combined with wastes from
other parts of the complex.
Sources of process waste water flows at Plant 20303 include
direct process contact water and washdowns. Direct process
contact water is from settling-tank overflow and amounts to
1,780 liters per metric ton (t»27 gallons per short ton) of
sodium fluoride produced on an average daily basis.
Washdown contributes ten times this amount, or 17,800 liters
per metric ton (4,270 gallons per short ton), to the total
process waste water effluent of 19,580 liters per metric ton
(1,700 gallons per short ton) of sodium fluoride product.
This waste water is combined with the waste effluents from
the production of numerous other chemicals and discharged to
a central treatment facility, where the wastes are processed
prior to final discharge to a surface receiving stream.
Wastewater Characteristics . . . •
chemical characteristics of untreated sodium fluoride
process waste water at Plant 20302 are presented in Table
18. This waste water is characterized by high
concentrations of pH, TSS, TDS, and fluoride. The pH can be
attributed to the use of concentrated caustic soda as a raw
material for the process. Suspended solids present in the
waste water are most likely silicates, wasted from the
separator, and sodium fluoride particles from scrubber
blowdown. The excessively high dissolved-solids content of
the process waste water is due to high concentrations of
sodium ions and fluoride ions in the separator waste water.
Fluorides in the process effluent are present in dissolved
and suspended form. Both the scrubber blowdown and
133
-------
TABLE 19. WATER CONSUMPTION OF PROCESSES FOR PRODUCTION OF
SODIUM FLUORIDE (THREE PLANTS)
WATER-USING
OPERATION
Boiler Feed
Noncontact Cooling
Evaporation
Wet Scrubber
Process Waste
Reaction Product*
Washdown
Total Water
Consumption
WATER CONSUMPTION
PLANT 20301
[/metric
ton
2,300
_
-
—
—
—
-
2,300
gal/short
ton
551.3
-•
_
_
—
_
-
551.3
PLANT 20302
I/metric
ton
—
-
618
476
2,984
-217
- .
3,861
gal/short
ton
—
-
148.1
114.1
715.3
52.0
-
925.5
PLANT 20303
I /metric
ton
_
12,593
-
—
681
—
10,211
23,485
gal/short
ton
_
3,018.5
-
—
163.2
—
2,447.6
5,629.4
•Water produced from chemical reaction. This is a water source and has a negative effect on water
consumption if recycled to the process.
134
-------
separator wastes contribute to the high fluoride content of
process waste water from Plant 20302.
Chemical characteristics of untreated sodium fluoride
process wastewaters at Plant 20303 are not available, due to
combination of these wastes with those of numerous other
chemical processes.
135
-------
Page Intentionally Blank
-------
SECTION VI
SELECTION OF POLLUTANT PARAMETERS
INTRODUCTION
During the course of the investigation preceding development
of the pretreatment standards, a wide range of potential
pollutant parameters was identified. The identification of
potential pollutant parameters for each subcategory covered
in this study was based on: (1) the presence of a
particular pollutant in the raw source material; (2)
chemicals used in processing the desired chemical; (3) the
presence of the pollutant in the untreated waste water from
a subcategory; and (4) the availability of pretreatment
control technology to remove the pollutant. The potential
pollutant parameters were then divided into (a) those
parameters selected as pollutants of significance (with the
rationale for their selection) and (b) those that are not
deemed significant (with the rationale for their rejection) .
GUIDELINE PARAMETER-SELECTION CRITERIA
The final selection of parameters for use in developing
pretreatment standards was based primarily on the following
criteria:
(1) Constituents which are frequently present in
inorganic chemical plant discharges in
concentrations deleterious to human, animal, fish
and aquatic organisms, and which pass through or
are removed in only small quantities at a POTW.
(2) Constituents which have a toxic effect on the
microbial population of a POTW, thus decreasing or
completely halting the treatment capabilities of
the POTW.
(3) Constituents which tend to clog, corrode, or in
some way harm the POTW1s equipment and facilities.
(I) The existence of technology for the reduction or
removal, at an economically practicable cost, of
the pollutants in question.
137
-------
SIGNIFICANCE AND RATIONALE FOR SELECTION OF POLLUTANT
PARAMETERS
Acidity and Alkalinity--pJ|
Although not a specific pollutant, pH is related to the
acidity or alkalinity of a waste water stream. It is not a
linear or direct measure of either; however, it may properly
be used as a surrogate for monitoring to control both excess
acidity and excess alkalinity in water. The term pH is used
to describe the hydrogen-ion/hydroxyl-ion balance in water.
Technically, pH is the hydrogen-ion concentration or
activity present in a given solution. pH numbers are' the
negative logarithms of the hydrogen ion concentration. A pH
of 7 indicates neutrality or a balance between free hydrogen
and free hydroxyl ions. Solutions with a pH above 7 are
alkaline, while a pH below 7 indicates that the solution is
acid.
Knowledge of the pH of water or waste water is useful in
determining necessary measures for corrosion control,
pollution control, and disinfection. Waters with a pH below
6.0 are corrosive to waterworks structures, distribution
lines, and household plumbing fixtures, and such corrosion
can add such constituents to drinking water as iron, copper,
zinc, cadmium, and lead. Low-pH waters tend not only to
dissolve metals from structures and fixtures but also to
redissolve or leach metals from sludges and bottom
sediments. The hydrogen-ion concentration can affect the
"taste" of the water; at a low pH, water tastes "sour."
Extremes of pH or rapid pH changes can exert stress
conditions^ or kill aquatic life outright. Even moderate
changes from "acceptable" criteria limits of pH are
deleterious to some species. The relative toxicity to
aquatic life of many materials is increased by changes in
the water pH. For example, metallocyanide complexes can
increase, a thousand-fold in toxicity with a drop of 1.5 pH
units, similarly, the toxicity of ammonia is a function of
pH. The bactericidal effect of chlorine, in most cases, is
less as the pH increases, and it is economically
advantageous to keep the pH close to 7.
Total Suspended Solids (TSS}
Suspended solids include both organic and inorganic
materials. The inorganic compounds include sand, silt, and
clay. The organic fraction includes such materials as
grease, oil, tar, and animal and vegetable waste products.
These solids may settle out rapidly, and bottom deposits are
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often a mixture of both organic and inorganic solids.
Solids may be suspended in water for a time and then settle
to the bed of the stream or lake. These solids, discharged
with man's wastes, may be inert, slowly biodegradable
materials, or rapidly decomposable substances. While in
suspension, they increase the turbidity of the water, reduce
light penetration, and impair the photosynthetic activity of
aquatic plants.
Suspended solids in water interfere with many industrial
processes and cause foaming in boilers and incrustations on
equipment exposed to such water—especially, as the
temperature rises. They are undesirable in process water
used in the manufacture of steel, in the textile industry,
in laundries, in dyeing, and in cooling systems.
Solids in suspension are aesthetically displeasing. When
they settle to form sludge deposits on the stream or lake
bed, they are often damaging to life in the water. Solids,
when transformed to sludge deposits, may do a variety of
damaging things, including, blanketing the stream or lake bed
and thereby destroying the living spaces for those benthic
organisms that would otherwise occupy the habitat, when of
an organic nature, solids use a portion or all of the
dissolved oxygen available in the area. Organic materials
also serve as a food source for sludgeworms and associated
organisms.
Disregarding any toxic effect attributable to substances
leached out by water, suspended solids may kill fish and
shellfish by causing abrasive injuries and by clogging the
gills and respiratory passages of various aquatic fauna.
Indirectly, suspended solids are inimical to aquatic life,
because they screen out light, and they promote and maintain
the development of noxious conditions through oxygen
depletion. This results in the killing of fish and fish
food organisms. Suspended solids also reduce the
recreational value of the water.
Floor and equipment washings, filter-backwash water,
emissions-control scrubber water, centrifuge washwater, and
leaks and spills may have high total-suspended-solids
levels.
Oil and Grease
Because of widespread use, oil and grease occur often in
waste water streams. These oily wastes may be classified as
follows:
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(1) Light Hydrocarbons—These include light fuels, such
as gasoline, kerosene, and jet fuel, and
miscellaneous solvents used for industrial
processing, decreasing, or cleaning purposes. The
presence of these light hydro carbons may make the
removal of other, heavier oily wastes more
difficult.
(2) Heavy Hydrocarbons, Fuels, and Tars—These include
the crude oils, diesel oils, 16 fuel oil, residual
oils, slop oils, and (in some cases) asphalt and
road tar.
(3) Lubricants and Cutting Fluids—These generally fall
into two classes; non-emulsifiable oils (such as
lubricating oils and greases) and emulsifiable oils
(such as watersoluble oils, rolling oils, cutting
oils, and drawing compounds). Emulsifiable oils
may contain fat, soap, or various other additives.
(4) Vegetable and Animal Fats and Oils—These originate
primarily from processing of foods and natural
products.
These compounds can settle or float and may exist as solids
or liquids, depending upon factors such as method of use,
production process, and temperature of waste water.
Oil and grease, even in small quantities, cause troublesome
taste and odor problems, scum lines from these agents are
produced on water treatment-basin walls and other
containers. Fish and water fowl are adversely affected by
oils in their habitat. Oil emulsions may adhere to the
gills of fish, causing suffocation, and the flesh of fish is
tainted when microorganisms that were exposed to waste oils
are eaten. Deposition of oil in the bottom sediments of
water can serve to inhibit normal benthic growth. Oil and
grease exhibit an oxygen demand.
Levels of oil and grease which are toxic to aquatic
organisms vary greatly, depending on the type and the
species susceptibility. However, it has been reported that
crude oil in concentrations as low as 0,3 mg/1 is extremely
toxic to freshwater fish. It has been recommended that
public water-supply sources be essentially free from oil and
grease.
Oil and grease in quantities of 100 1/sq km (10 gal/sq mile)
show up as a sheen on the surface of a body of water. The
presence of oil slicks prevents the full aesthetic enjoyment
of water. The presence of oil in water can also increase
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the toxicity of other substances being discharged into the
receiving bodies of water. Municipalities frequently limit
the quantities of oil and grease that can be discharged to
their waste watertreatment system by industry.
Aluminum (Al
Aluminum is an abundant metal found in the earth's crust
(8.1%), but it is never found free in nature. Pure
aluminum, a silvery white metal, possesses many desirable
characteristics. It is light; has a pleasing appearance,
can easily be formed, machined, or cast; has a high thermal
conductivity; is nonmagnetic and nonsparking; and stands
second among metals in the scale of malleability and sixth
in ductility.
Although the metal itself is insoluble, some of its salts
are readily soluble. Other aluminum salts are quite
insoluble, however; consequently, aluminum is not likely to
occur for long in surface water, because it precipitates and
settles or is absorbed as aluminum hydroxide and aluminum
carbonate. Aluminum is also nontoxic, and its salts are
used as coagulants in water treatment. Aluminum is commonly
used in cooking utensils, and there is no known
physiological effect on man -from low concentrations of this
metal in drinking waters.
Chromium
Chromium is an elemental metal, usually found as a chromite
(FeCr20§). The metal is normally processed by reducing the
oxide with aluminum.
Chromium and its compounds are used extensively throughout
industry. The metal is used to harden steel and as an
ingredient in other useful alloys. Chromium is also used in
the electroplating industry as an ornamental and corrosion-
resistant plating on steel and can be used in pigments and
as a pickling acid (chromic acid).
The two most prevalent chromium forms found in industry
waste waters are hexavalent and trivalent chromium. Chromic
acid, used in industry, is a hexavalent chromium compound
which is partially reduced to the trivalent form during use.
Chromium can exist as either trivalent or hexavalent
compounds in raw waste streams. Hexavalent chromium
treatment involves reduction to the trivalent form prior to
removal of chromium from the waste stream as a hydroxide
precipitate.
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Chromium, in its various valence states, is hazardous to
man. It can produce lung tumors when inhaled and induces
skin sensitizations. Large doses of chromates have
corrosive effects on the intestinal tract and can cause
inflammation of the kidneys. Levels of chromate ions that
have no effect on man appear to be so low as to prohibit
determination to date. The recommendation for public
drinking water supplies is that such supplies contain no
more than 0.05 mg/1 total chromium.
The toxicity of chromium salts to fish and other aquatic
life varies widely with the species, temperature, pH,
valence of the chromium, and synergistic or antagonistic
effects—especially, those of hard water, studies have
shown that trivalent chromium is more toxic to fish of some
types than hexavalent chromium. Other studies have shown
opposite effects. Fish food organisms and other lower forms
of aquatic life are extremely sensitive to chromium, and it
also inhibits the growth of algae. Therefore, both
hexavalent and trivalent chromium must be considered harmful
to particular fish or organisms.
Copper-
Copper is an elemental metal that is sometimes found free in
nature and is found in many minerals, such as cuprite,
malachite, azurite, chalcopyrite, and bornite. Copper is
obtained from these ores by smelting, leaching, and
electrolysis. Significant industrial uses are in the
plating, electrical, plumbing, and heating equipment
industries. Copper is also commonly used with other
minerals as an insecticide and fungicide.
Traces of copper are found in all forms of plant and animal
life, and it is an essential trace element for nutrition.
Copper is not considered to be a cumulative systemic poison
for humans, as it is readily excreted by the body, but it
can cause symptoms of gastroenteritis, with nausea and
intestinal irritations, at relatively low dosages. The
limiting factor in domestic water supplies is taste.
Threshold concentrations for taste have been generally
reported in the range of 1.0 to 2.0 mg/1 of copper, while
concentrations of 5 to 7.5 mg/1 have made water completely
undrinkable. It has been recommended that the copper in
public water supply sources not exceed 1 mg/1.
Copper salts cause undesirable color reactions in the food
industry and cause pitting when deposited on some other
metals, such as aluminum and galvanized steel. The textile
industry is affected when copper salts are present in water
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used for processing of fabrics. Irrigation waters
containing more than miniate quantities of copper can be
detrimental to certain crops. The toxicity of copper to
aquatic organisms varies significantly, not only with the
species, but also with the physical and chemical
characteristics of the water, including temperature,
hardness, turbidity, and carbon dioxide content. In hard
water, the toxicity of copper salts may be reduced by the
precipitation of copper carbonate or other insoluble
compounds. The sulfates of copper and zinc, and of copper
and cadmium, are synergistic in their toxic effect on fish.
Copper concentrations less than 1 mg/1 have been reported to
be toxic-particularly, in soft water—to many kinds of fish,
crustaceans, mollusks, insects, phytoplankton, and
zooplankton. concentrations of copper, for example, are
detrimental to some oysters above 0.1 ppm. Oysters cultured
in sea water containing 0.13 to 0.5 ppm of copper deposit
the metal in their bodies and become unfit as a food
substance.
Iron (Fe) , . '
Iron is an abundant metal found in the earth's crust. The
most common iron ore is hematite, from which iron is
obtained by reduction with carbon. other forms of
commercial ores are magnetite and taconite. Pure iron is
not often found in commercial use, but it is usually alloyed
with other metals and elements, the most common being
carbon.
Iron is the basic element in the production of steel and
steel alloys. Iron with carbon is used for casting of major
parts of machines, and it can be machined, cast, formed, and
welded. Ferrous iron is used in paints, while powdered iron
can be sintered and used in powder metallurgy. Iron
compounds are also used to precipitate other metals and
undesirable minerals from industrial waste water streams.
Iron is chemically reactive and corrodes rapidly in the
presence of moist air and at elevated temperatures. In
water and in the presence of oxygen, the resulting products
of iron corrosion may be pollutants in water. Natural
pollution occurs from the leaching of soluble iron salts
from soil and rocks and is increased by industrial waste
water from pickling baths and other solutions containing
iron salts.
Corrosion products of iron in water cause staining of
porcelain fixtures, and ferric iron combines with tannin to
produce a dark violet color. The presence of excessive iron
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in water discourages cows from drinking and, thus, reduces
milk production. High concentrations of ferric and ferrous
ions in water kill most fish introduced to the solution
within a few hours. The killing action is attributed to
coatings of iron hydroxide, precipated on the gills. Iron-
oxidizing bacteria are dependent on iron in water for
growth. These bacteria form slimes that can affect the
esthetic values of bodies of water and cause stoppage of
flows in pipes.
Iron is an essential nutrient and micronutrient for all
forms of growth. Drinking-water standards in the U.S. have
set a recommended limit of 0,3 mg/1 of iron in domestic
water supplies, based not on physiological considerations,
but rather on the aesthetic and taste considerations of iron
in water.
Lead (_Pb)
Lead is used in various solid forms, both as a pure metal
and in several compounds. Lead appears in some natural
waters—especially, in those areas where mountain limestone
and galena are found. Lead can also be introduced into
water from lead pipes by the action of the water on the
lead.
Lead is a toxic material that is foreign to humans and
animals. The most common form of lead poisoning is called
plumbism. Lead can be introduced into the body from
atmospheres containing lead, or from food and water. Lead
cannot be easily excreted and is cumulative in the body over
long periods of time, eventually causing lead poisoning with
the ingestion of an excess of 0.6 mg per day over a period
of years. -It has been recommended that 0.05 mg/1 lead not
be exceeded in public watersupply sources.
Chronic lead poisoning has occurred among animals at levels
of 0.18 mg/1 of lead in soft water and by concentrations
under 2.4 mg/1 in hard water. Farm animals are poisoned by
lead more frequently than any other poison. Sources of this
occurrence include paint and water, with the lead in
solution as well as in suspension. Each year, thousands of
wild water fowl are poisoned from lead shot that is
discharged over feeding areas and ingested by the water
fowl. The bacterial decomposition of organic matter is
inhibited by lead at levels of 0.1 to 0.5 mg/1.
Fish and other marine life have had adverse effects from
lead and salts in their environment. Experiments have shown
that small concentrations of heavy metals, especially lead,
have caused a film of coagulated mucus to form, first over
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the gills and then over the entire body, probably causing
suffocation of the fish due to this obstructive layer.
Toxicity of lead is increased with a reduction of dissolved-
oxygen concentration in the water.
Nickel (Ni
Elemental nickel seldom occurs in nature, but nickel
compounds are found in many ores and minerals. As a pure
metal, it is not a problem in water pollution, because it is
not affected by, or soluble in, water. Many nickel salts,
however, are highly soluble in water.
Nickel is extremely toxic to citrus plants. It is found in
many soils in California—generally, in insoluble form—but
excessive acidification of such soil may render its nickel
soluble, causing severe injury to or the death of plants.
Many experiments with plants in solution cultures have shown
that nickel at 0.5 to 1.0 mg/1 is inhibitory to growth.
Nickel salts can kill fish at very low concentrations. Data
for the fathead minnow show death occurrin9? in the range of
5 to 43 mg/1, depending on the alkalinity of the water.
Nickel is present in coastal and open ocean concentrations
in the range of 0.1 to 6.0 micrograms per liter, although
the most common values are 2 to 33 micrograms per liter.
Marine animals contain up to 400 micrograms per liter, and
marine plants contain up to 3,000 micrograms per liter. The
lethal limit of nickel to some marine fish has been reported
to be as low as 0.8 ppm (mg/1) (800 micrograms per liter).
Concentrations of 13.1 mg/1 have been reported to cause a
50-percent reduction of photosynthetic activity in the giant
kelp (Macrocystis pyrifers) in 96 hours, and a low
concentration has been found to kill oyster eggs.
Silvey (Ac?)
silver is a soft, lustrous, white metal that is insoluble in
water and alkali. It is readily ionized by electrolysis and
has a particular affinity for sulfur and halogen elements.
In nature, silver is found in the elemental state and
combined in ores such as argentite (Agj2S), cerargyrite
(Agel) , proustite (Ag3As,3J , and pyrargyrite (Ag3_SbS3J .
From these ores, silver ions may be leached into ground
waters and surface waters; but, since many silver salts,
such as the chloride, sulfide, phosphate, and arsenate, are
insoluble, silver ions do not usually occur in significant
concentration in natural waters.
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Silver is used extensively in electroplating, photographic
processing, electrical-equipment manufacture, soldering and
brazing, and battery manufacture. Of these, the two major
sources of soluble silver wastes are the photographic and
electroplating industries, with about 30$ of U.S. industrial
consumption of silver going into the photographic industry.
Silver is also used in its basic metal state for such items
as jewelry and electrical contacts.
While metallic silver itself is not considered to be
poisonous for humans, most of its salts are poisonous due to
anions present. Silver compounds can be absorbed in the
circulatory system, and reduced silver can be deposited in
the various tissues of the body. A condition known as
argyria, a permanent greyish pigmentation of the skin and
mucous membranes, can result. Concentrations in the range
of 0.1 to 1 nig/liter have caused pathologic changes in the
kidneys, liver, and spleen of rats.
Silver is recognized as a bactericide, and doses as low as
0.000001 to 0.5 mg/1 have been reported as sufficient to
sterilize water.
Zinc
Occurring abundantly in rocks and ores, zinc is readily
refined into a stable pure metal and is used extensively as
a metal, an alloy, and a plating material. In addition,
zinc salts are also used in paint pigments, dyes, and
insecticides. Many of these salts (for example, zinc
chloride and zinc sulfate) are highly soluble in water;
hence, it is expected that zinc might occur in many
industrial wastes. On the other hand, some zinc salts (zinc
carbonate, zinc oxide, zinc sulfide) are insoluble in water,
and consequently, it is expected that some zinc will
precipiate and be removed readily in many natural waters.
In soft water, concentrations of zinc ranging from 0.1 to
1.0 mg/1 have been reported to be lethal to fish. zinc is
thought to exert its toxic action by forming insoluble
compounds with the mucous that covers the gills, by damage
to the gill epithelium, or possible by acting as an internal
poison. The sensitivity of fish to zinc varies with
species, age, and condition, as well as with the physical
and chemical characteristics of the water. Some
acclimatization to the presence of the zinc is possible. It
has also been observed that the effects of zinc poisoning
may not become apparent immediately, so that fish removed
from zinc-contaminated to zinc-free water may die as long as
H8 hours after the removal. The presence of copper in water
may increase the toxicity of zinc to aquatic organisms,
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while the presence of calcium or hardness may decrease the
relative toxicity.
A complex relationship exists among zinc concentrations,
dissolved oxygen, pH, temperature, and calcium and magnesium
concentrations. Prediction of harmful effects has been less
than reliable, and controlled studies have not been
extensively documented.
Concentrations of zinc in excess of 5 mg/1 in public water-?
supply sources cause an undesirable taste which persists
through conventional treatment* Zinc can have an adverse
effect on man and animals at high concentrations.
Observed values for the distribution of mine in ocean waters
vary widely. The major concern with zinc compounds in
marine waters is not one of acute lethal effects, but rather
one of the long-term sublethal effects of the metallic
compounds and complexes. From the point of view of acute
lethal effects, invertebrate marine animals seem to be the
most sensitive organisms tested.
A variety of freshwater plants tested manifested harmful
symptoms at concentrations of 10 mg/1. Zinc sulfate has
also been found to be lethal to many plants, and it could
impair agricultural uses of the water,
Fluoride and Fluorine |fj_ -
Fluorine is the most reactive of the nonmetals and is never
found free in nature. It is a constituent of fluorite or
fluorspar (calcium fluoride) and cryolite (sodium aluminum
fluoride). Due to their origins, fluorides in high
concentrations are not common constituents of natural
surface waters; however, they may occur in hazardous
concentrations in ground waters.
Fluoride can be found in plating rinses and in glass-etching
rinse waters. Fluorides are also used as a flux in the
manufacture of steel, for preserving wood and mucilages, as
a disinfectant, and in insecticides.
Fluorides in sufficient quantities are toxic to humans, with
doses of 250 to 450 mg giving severe symptoms and 4.0 grams
causing death. A concentration of 0.5 g/kg of body weight
has been reported as a fatal dosage.
There are numerous articles describing the effects of
fluoride-bearing waters on dental enamel of children; these
studies lead to the generalization that water containing
less than 0.9 to 1.0 mg/1 of fluoride will seldom cause
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mottled enamel in childrenj for adults, concentrations less
than 3 or « mg/1 are not likely to cause endemic cumulative
fluorosia and skeletal effects. Abundant literature is also
available describing the advantages of maintaining 0,8 to
1.5 mg/1 of fluoride ion in drinking water to aid in th-
reduction of dental decay—especially, among children. Tl
recommended maximum levels of fluoride in public water-
supply sources range from 1.4 to 2.4 mg/1.
Fluorides may be harmful in certain industries—
particularly, those involved in the production of food,
beverages, Pharmaceuticals, and medicines. Fluorides found
in irrigation waters in high concentrations (up to 360 mg/1)
have caused damage to certain plants exposed to these
waters. Chronic fluoride poisoning of livestock has been
observed in areas where water contained 10 to 15 mg/1
fluoride, concentrations of 30 to 50 mg/1 of fluoride in
the total ration of dairy cows is considered the upper safe
limit. Fluoride from waters apparently does not accumulate
in soft tissue to a significant degree; it is transferred to
a very small extent into milk, and to a somewhat greater
degree into eggs. Data for fresh water indicates that
fluorides are toxic to fish at concentrations higher than
1.5 mg/1.
SIGNIFICANCE AND RATIONALE FOR REJECTION OF FOLLOTANT
PARAMETERS
General
A number of pollution parameters besides those selected and
just discussed were considered in each category but were
rejected for one or more of these reasons:
(1) Simultaneous reduction is achieved with another
parameter which is limited.
(2) Treatment technologies available at this time to
reduce concentrations or loads of the parameter
(i.e., total artificial evaporation, ion exchange,
or reverse osmosis) are uneconomical or
impractical.
(3) The parameter was not usually observed in
quantities sufficient to warrant regulations.
(4) There are insufficient data on loadings or
treatment methods which might be employed.
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Parameters listed in this section are parameters which have
been rejected as not applicable for the control of effluent
quality for the chemicals considered tinder this study,
Total Dissolved solids CTOS)
Raw material and product salts present in process waste
water create extremely high dissolved-solids levels.
However, dilution of the waste water within the sewer to
reduce its toxicity and, more importantly, the lack of
practical and economical technology to remove dissolved
solids preclude control.
Calcium (Ca| • •
Calcium as an elemental metal does not occur naturally,
because it is oxidized readily in air and reacts in water.
Its most common form is limestone.
Calcium is used as a reducing agent in preparing other
metals and as a dexodizer, desulfurizer, or decarburimer for
various ferrous and nonferrous alloys. It is also used as
an alloying agent with aluminum, beryllium, copper, lead,
and magnesium.
Calcium is essential to human body development, and minimum
daily requirements have been set for proper nutrition.
Calcium contributes to the hardness in water. Calcium
reduces the toxicity of many chemical compounds and is used
extensively in water treatment in the form of lime.
Potassium .JK).,
One of the more common elements, potassium constitutes 2.1
percent of the crust of the earth and occurs in many
minerals. It is one of the most active metals and reacts
vigorously with oxygen and water. For this reason, it is
not found free in nature, but only in the ionized or
molecular form. Potassium resembles sodium in many of its
properties, and potassium salts can be substituted for
sodium salts in many industrial applications. The sodium
salts, however, are generally less expensive and, hence,
more frequently used. For fertilizers, some varieties of
glass, and a few other purposes, potassium salts are
indispensable. Because the common salts of potassium are
extremely soluble, they are not readily separated from water
by natural process other than evaporation.
In low to moderate concentrations, potassium is essential as
a nutritional element for man, animals and plants. At
higher levels, however, it acts as a cathartic towards
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humans and can be toxic to fish in soft or distilled waters.
The toxicity towards fish can be reduced by calcium and, to
a lesser extent, by sodium.
Sodium (Na
Sodium is present in several chemical industry effluents.
However, there are insufficient data on sodium and no
economical or practical technology for its removal available
at this time to justify consideration of sodium as a harmful
pollutant.
Carbonate fC03
There are insufficient data for dissolved carbonates to
justify consideration of this ion as a harmful pollutant.
Chloride fCl)
While chloride concentrations in many cases are elevated,
there are no economical or practical methods for removal at
this time which can be employed on a large scale.
Sulfate (SOg)
Although, in some cases, industry sulfate concentrations
were found to be high, sulfate is relatively nontoxic and is
present in the natural environment in high concentrations.
No practical treatment methods exist to remove sulfate at
this time on a large scale. Lime treatment, in itself,
causes sulfate to precipitate out as gypsum.
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SECTION VII
CONTROL AND PRETREATMENT TECHNOLOGY
INTRODUCTION
In the context of this supplement to the main effluent
guidelines document for the Inorganic Chemicals Industry,
the term "control technology" refers to practices employed
to reduce the volumes of waste water discharged to PQTWs.
11 Pretreatment technology" refers to practices applied to
waste water streams to reduce the concentrations of
pollutants in the streams before discharge to municipal
systems.
The control and pretreatment technologies available to that
part of the Inorganic Chemicals Industry discharging to
POTWs are, in many ways, the same as those available to that
segment of the industry which directly discharges or
recycles process waste water. The very significant differ-
ence is that POTW dischargers mayt and do, avail themselves
of public facilities for treatment of process waste water.
As a result, process waste water discharges from POTW users
generally -receive less treatment or, in many cases, no
treatment before discharge. The principal pretreatment
technology employed is pH adjustment, precipitation, and
solids removal prior to discharge to POTWs.
The practice of water recycle as a control measure appears
to be employed to at least the same degree by POTW
dischargers as by direct dischargers. Water recycle by POTW
dischargers may be the result of jninimizing--or, in some
cases, completely avoiding—sewer-district user fees which
are based, in part, on volumes discharged to the POTWs.
Thus, there is added impetus for the POTW discharger to
recycle process water above that of reducing, water
consumption.
CONTROL AND PRSTREATMENT TECHNOLOGY AVAILABLE
Each of the techniques currently employed in those segments
of the Inorganic chemicals Industry covered by this
document, as well as technology which might be employed in
present or future operations for control or pretreatment of
wastes, is discussed in this subsection in general terms.
Details as they apply to typical operations in each
subcategory of the industry are given under "TYPICAL
PRETREATMENT OPERATIONS" for that chemical subcategory (by
subcategory name), later in this section. The intervening
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material describes "TICHNIQUIS FOR REDUCTION OF WASTEWATIR
VOLUME" and discusses the approach used in the detailed
discussions for the chemical subcategories.
Clajrifiers and Thickeners
A method of removing large amounts of suspended solids from
waste water is the use of Clarifiers, which are essentially
large tanks with directing and segregating systems. The
design of these devices provides for concentration and
removal of suspended and settleabla solids in one effluent
stream and a clarified liquid in the other. Through proper
design, application, and operation, clarified waters may
have extremely low solids content,
Clarifiers may range in design from simple units to more
complex systems involving sludge-blanket pulsing or sludge
recycle to improve settling and increase the density of the
sludge. Settled solids from Clarifiers are removed
periodically or continuously for either disposal or recovery
of contained metal values.
Thickeners are used when the main purpose is to produce a
clarified overflow with a concentrated effluent in the
underflow.
Clarifiers have a number of distinct advantages over
settling pondsj
(1) Less land space is required. Area-for-area, these
devices are much more efficient in settling capacity
than ponds.
(2) Influences of rainfall are reduced compared to ponds.
If desired, the Clarifiers can be covered.
(3) Since the external construction of Clarifiers consists
of concrete or steel (in the form of tanks),
infiltration and rainwater runoff influences do not
exist.
(H) Clarifiers can generally be placed adjacent to a plant,
making reclaim water available nearby with minimal
pumping requirements.
The use of flocculants to enhance the performance of
Clarifiers is common practice,
Clarifiers also suffer some distinct disadvantages compared
to ponds:
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(1) They have mechanical parts and, thus, require
maintenance.
(2) They have limited storage capacity for either clarified
water or settled solids.
(3) The internal sweeps and agitators in clarifiers require
more power and energy foj: operation than settling ponds.
Flocculation
This treatment process consists basically of adding reagents
to the treated waste stream to promote settling of suspended
solids. The solids may be deposited in settling ponds
(where high suspended solids are involved) or in clarifier
tanks (in cases of lower solids loads)»
Flocculating agents increase the efficiency of settling
facilities and are of several general types: ferric
compounds, lime, aluminum sulfate, and cationic or anionic
polyelectrolytes. causticized wheat and corn starch have
also been used. The ionic types, such as alum, ferrous
sulfate, lime, and ferric chloride, function by destroying
the repelling double-layer ionic charges around the
suspended particles and thereby allowing the particles to
attract each other and agglomerate. Polymeric types
function by forming physical bridges from one particle to
another and thereby agglomerating the particles. Recyclable
magnesium carbonate has also been proposed as a flocculant
in domestic water treatment.
Flocculating agents are added to the water to be treated
under controlled conditions of concentration, pH, mixing
time, and temperature. They act to upset the stability of
the colloidal suspension by charge neutralization and
flocculation of suspended solids, thus increasing the
effective diameter of these solids and increasing their
subsequent settling rate.
Flocculating agents are most commonly used after the larger,
more readily settled particles (and loads) have been removed
by a settling pond, hydrocyclone, or other treatment.
Agglomeration, or flocculation, can then be achieved with
less reagent, and with less settling load on the polishing
pond or clarifier,
Flocculation agents can be used with minor modifications and
additions to existing treatment systems, but the costs for
the flocculating chemicals may be significant. Ionic types
are used in concentrations of 10 to 100 mg/1 in the waste
153
-------
water, while the highest-priced polymeric types are
effective in concentrations of 2 to 20 mg/1.
The effectiveness and performance of individual flocculating
systems may vary over a substantial range with respect to
suspended-solids removal, accessory removal of soluble
components by adsorptive phenomena, and operating
characteristics and costs. Specific system performance must
be analyzed and optimized with respect to mixing time,
flocculant addition level, settling (detection) time,
thermal and wind-induced mixing, and other factors.
Centri fugation
eentrifugation, which may be considered as a form of forced
or assisted settling, may be feasible in specific control
applications. The presence of abrasive components or
significant amounts of the solid material smaller than
approximately 5 micrometers (less than 0.0002 inch) in
diameter in the treated water would tend to disqualify
centrifugation as a solids-removal option.
Neutrali za tign .
Adjustment of pH is the simplest chemical treatment
practiced by industry. The addition of either acidic or
basic constituents to a waste water stream to achieve
neutralization generally influences the behavior of both
suspended and dissolved components. In most instances of
interest, waste waters are treated by base addition to
achieve a pH in the range of 6.0 to 9.0.
Acid waste streams may be neutralized by addition of a
variety of basic reagents, including lime (Cao)f limestone
(CaCO3) f dolomite (CaMg (CO3) 2) , magnesite (MgCO.3) , sodium
hydroxide, soda ash (sodium carbonate)t ammonium hydroxide,
and others, to raise the pH of treated waste streams to the
desired level. Lime is often used because it is inexpensive
and easy to apply.
Ammonia neutralization is most frequently a processing
technique, where ammonia affords a strong advantage in being
volatile in the final product, allowing the recovery of
nearly pure oxides. In waste treatment, its volatility is a
disadvantage. Because of the COD it presents, its toxicity,
and the production of undesirable nitrites and nitrates as
oxidation products, its use is not widespread, and it is not
desirable for waste treatment.
Since many heavy metals form insoluble hydroxides in highly
basic solutions, sedimentation prior to neutralization may
-------
prevent, the resolubilization of these materials and may
simplify subsequent waste-treatment requirements.
Essentially any waste water stream may be treated to a final
pH within the range of 6.0 to 9.0. Generally, the stream
will be sufficiently uniform to allow adequate pH control
based only on the volume of flow . and predetermined dosage
rates, with periodic adjustments based on effluent pH.
Automated systems which monitor and continuously adjust the-
concentration of reagents added to the waste water are also
currently available and in use.
As discussed previously, pH control is often used to control
solubility (also discussed below under Chemical
Precipitation Processes) . Examples of pH control being used
for precipitating undesired pollutants are:
(1) Fe+3 +'30H- = Fe(OH)!
(2) Mn+2 + 20H- = Mn{OH)2.
(3) Zn+2 + OH- = Zn(OH)2
(4) Pb+2 + 20H- * Pb(OH)2
(5) CU+2 20H- • Cu(OH)!
Reaction (1) is used for removal of iron contaminants.
Reaction (2) is used for removal of manganese from
manganese- containing waste water. Reactions (3) , (4) , and
(5) are used on waste water containing copper, lead, and
zinc salts. The use of lime to attain a pH of 7 will
theoretically reduce heavy metals to these levels (Reference
10) :
Metal Concentration
at pH 7)
Cu+2 0.2 to 0.3
Zn+2 1.0 to 2.5
Cd-t-2 1.0
The careful control of pH, therefore, has other ancillary
benefits, as illustrated above. The use of pH and
solubility relationships to improve removal of waste water
contaminants is further developed below.
Chemical Precipitation Processes
155
-------
General Considera tions. The removal of materials from
solution by the addition of chemicals which form insoluble
(or sparingly soluble) compounds with them is a common
practice in both chemical-production processes and waste
treatment. It is especially useful in the removal of heavy
metals and fluoride from waste water effluents prior to
discharge.
To be successful, direct precipitation depends primarily
upon two factors;
(1) Achievement of a sufficient excess of the added ion to
drive the precipitation reaction to completion.
(2) Removal of the resulting solids from the waste stream.
If the first requirement is not met, only a portion of the
pollutant (s) will be removed from solution, and desired
effluent levels may not be achieved. Failure to remove the
precipitates formed prior to discharge is likely to lead to
redissolution, since ionic equilibria in the receiving
stream will not, in general, be those created in treatment.
Effective sedimentation or filtration is, thus, a vital
component of a precipitation treatment system and frequently
limits the overall removal efficiency. Sedimentation may be
effected in the settling pond itself, in secondary or
auxiliary settling ponds, or in clarifiers.
The use of precipitation for waste water treatment varies
from lime treatment (to precipitate sulfates, fluorides,
hydroxides, and carbonates) to sodium sulfide precipitation
of copper, lead, and other toxic heavy metals. Alum
precipitation is also in use, to remove fluorides to lower
levels than lime precipitation. The following equations are
examples of precipitation reactions used for waste water
treatment;
(1) Fe+3 * Ca(OH)2 = Ca+2 + Fe(OH)3
(2) Mn+2 + Ca{OH)2 = Ca+2 * Mn(OH)J
(3) Zn+2 + Na2C03 = Na+ ZnCO3
(4) S04-2 + Ca(OH)2 = CaSOfJ + 20H-
(5) 2F- + Ca(OH)2 * CaF2 + 2OH-
One drawback of the precipitation reactions is that the
varying solubilities of unknown interactions of several
metal compounds, and the possibility of widely divergent
156
-------
formation and precipitation rates, limit the ability of this
treatment to deal with all waste constituents.
lime pre.elgitation« The use of lime to cause chemical
precipitation has gained widespread use in the Inorganic
Chemicals Industry because of its ease of handling, economyr
and effectiveness in treatment of a ' great variety of
dissolved materials. The use of other bases isr of course,
possible, as previously discussed. However, the use of lime
as a treatment reagent is probably the best-known and best-
studied method.
The treatment conditions, dosages, and final pH must be
optimized for any given waste stream, but, in general,
attainment of a pH of at least 9 is necessary to ensure
removal of heavy metals; it is necessary to attain a pH of
10 to" 12 in many instances.
The levels of concentration attainable in an actual
operating system may vary from the limits predicted on the
basis of purely theoretical considerations, but extremely
low levels of metals discharged have been reached by the use
of this treatment method. The minimum pH value for complete
precipitation of metal ions as hydroxides is shown in Figure
«n. . •
Purely theoretical considerations of metal-hydroxide
solubility relationships suggest that the metal levels
tabulated below are attainable (Reference 11).
Final Concentration
Metal ' (micrqgrams per literL • pH
Cu+2 1 to 8 9.5
Zn+2 10 to 60 10
Pb 1 8
Fe (total) 1 8
(if totally ferric)
Many factors, such as the effects of widely differing
solubility products, mixed-metal hydroxide complexing, and
metal chelation, render- these levels of only limited value
when assessing attainable concentrations in a treatment
system.
Among the metals effectively removed at basic pH are: As,
cd, cuf Cr+3, Fe, Mn, Ni, Pb, and Zn. For example, based
upon published sources, industry data, and analysis of
157
-------
Fiflure41. MINIMUM pH VALUE FOR COMPLETE PRECIPITATION OF METAL IONS
AS HYDROXIDES
111 A
9.0
ft 0
7 0
6.0
5.0
4.0
3.0
2.0
f.O
0.0
1
7.2
(
E.2
i
1.2
••M
t
\.<
5.3
8.4
1.3
1
).5
!
JJ
1
O.I
Fe+2 cd+2 Mn+2
LIME
NEUTRALIZATION
LIME PRECIPITATION
158
-------
samples, it appears that the concentrations given in the
tabulation below are routinely and reliably attained by
hydroxide precipitation (Reference 12).
Metal Concentration Metal concentration
fmq/1) • (Bg/1)
As 0.05 Mn 1.0
Cd 0.05 Ni 0.05
Cu 0.03 Pb 0.10
Cr+3 0.05 Zn 0.15
Fe 1.0
Lime precipitation "is widely used for the control of
fluoride, as well as for the removal of heavy metals. High
dosages • of lime .contribute excess calcium ions to the
solution, resulting in the precipitation of calcium
fluoride. The elevated pH produced by the lime enhances the
precipitation effectivenesss by shifting the HP « H+ + F~
towards the presence of free fluoride ions f which may be
precipitated. Published sources {References 13, 14, 15, and
16) indicate that lime is effective in removing fluoride to
concentrations of 20 mg/1 or lower. Effluents from
treatment with excess lime frequently approach the
theoretical solubility of calcium fluoride (8 mg/1 as
fluoride).
Alum Precipitation. Fluoride ions may be removed, to levels
appreciably lower than those obtained by lime treatment, by
precipitation with alum. Effluent levels of fluoride ions
on the order of 2 mg/1 are reported (in References 13 and
11) as a result of alum precipitation. Because reagents
costs are higher than for lime treatment, alum precipitation
is particularly suited to the treatment of solutions
containing relatively low initial fluoride concentrations.
It particularly well-suited to use as a polishing step
for further treatment of lime-precipitation effluents. In
such applications, it is important to remove the calcium
fluoride precipitate before adding the alum if maximum
treatment benefits are to be realized (Reference 13).
Alum may be added as ammonium alum (NH4A1 (SO4) 2.. 12H2.O) , or
as sodium or potassium alumf and may be used with sodium
hexametaphosphate, as described in Reference 13. Dosages
are generally in the range of 200 mg/1 to 600 mg/1 of alum,
depending on the initial fluoride-ion concentration and the
required effluent quality. In addition to fluoride removal,
the alum will,'of course, serve as a flocculant and serve to •
remove some residual suspended solids.
TECHNIQUES FOR REDOCTIOtl OF WASTEWATER VOLUME
159
-------
Pollutant discharges from inorganic chemical manufacturing
operations may be reduced by limiting the total volume of
discharge, as well as by reducing pollutant concentrations
in the waste stream. Techniques for reducing volumes
discharged include limiting water use, excluding incidental
water from the waste stream through segregation or
diversion, recycle or reuse of process water, dry collection
and solid wastes, and impoundment with solar evaporation.
In most cases, water use would already be reduced to the
extent practical, because of the existing incentives for
doing so (i.e., the high costs of pumping the high volumes
of water required, limited water availability, the cost of
water-treatment facilities, and POTW surcharges.)
Recycle of process water is currently practiced where it is
necessary due to water shortage, where it is advantageous,
or where the local permitting authority has required it.
Recycle is becoming, and will continue to become, a more
frequent practice. The benefits of recycle in pollution
abatement are manifold and frequently are economic as well
as environmental. By reducing the volume of discharge,
recycle not only reduces the gross pollutant load, but also
allows the employment of abatement practices which would be
uneconomical on the full waste stream,
Recyle may require some treatment of water prior to its
reuse. This may entail only settling of solids or pH
adjustment.
Impoundment is a technique practiced at many operations in
arid regions to reduce point discharges to, or nearly to,
zero. Its successful employment depends on favorable
climatic conditions (generally, less precipitation than
evaporation, although a slight excess may be balanced by
process losses and retention in product) and on availability
of land consistent with process-water requirements and
seasonal or storm precipitation influxes. In some instances
where impoundment is not practical on the full process
stream, impoundment and treatment of smaller, highly con-
taminated streams from specific processes may afford
significant advantages.
APPROACH FOR REMAINDER OP SECTION
Control and pretreatment technologies employed by POTW
dischargers and by direct dischargers are next discussed for
each chemical subcategory. Varying degrees of pretreatment
are discussed for a particular chemical when there is a
series of technologies available, the application of which
achieve additional pollutant reductions. In general.
160
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pretreatment technologies which achieve pollutant reductions
comparable to BPCTCA have been recommended.
TYPICAL PRETREATMENT OPERATIONS FOR ALUMINUM ' CHLORIDE
SUBCATSGORY
Control
Because of varying air-pollution control practices, some
aluminum chloride plants generate scrubber waste water,
while others do not. Water-pollution control technology for
the scrubber water differs between hydrous and anhydrous
aluminum chloride producers because economical zero-
discharge technology is not available at present for the
latter. The Development Document for Effluent Guidelines
for the Major Inorganic Chemicals Industry describes a
system at "Plant 125" whereby the anhydrous salt scrubber
water is recycled and a bleed is withdrawn for production of
a 28% aluminum chloride solution. The aluminum chloride
solution was reported to be sold as a flocculant. However,
a recent discussion with plant personnel indicates that the
bleed recovery system is not economically feasible, and the
waste is being discharged untreated. A caustic
neutralization and settling system is planned for the raw
scrubber waste stream in the near future.
Alternately, a scrubber water reuse system is employed at
Plant 19103, which produces the hydrous salt. The fumes
generated during the reaction of hydrochloric acid and
hydrated alumina (aluminum oxide), are captured in a wet
scrubber, and the total volume of scrubber water generated
is reintroduced to the reactor. Note that solids (mostly,
unreacted alumina) obtained from filtration of the product
are also reintroduced into the reactor, thus yielding
neither solid nor liquid waste. This system is outlined in
Figure H2.
Pretreatment
Because there are no known POTW dischargers in the
subcategory, there is no pretreatment technology presently
in use. of the three plants where water is known to be used
for emissions control, two are direct dischargers, and the
third plant has obtained zero discharge of process wastes.
As discussed in Section V, the raw waste water
characteristics are similar for production of both the
hydrous and anhydrous salts. Both wastes are amenable to
similar treatment technology, though control technology
capabilities differ, as indicated above.
161
-------
Figure 42. FLOW DIAGRAM SHOWING SCRUBBER-WATER REUSE IN PRODUCTION
OF HYDROUS ALUMINUM CHLORIDE ^PLANT 19103)
MAKEUP WATER
H-O
HYDRATED
ALUMINUM
OXIDE
HYDROCHLORIC
ACID
REACTOR
• FUMES-
RETURN SOLUTION-
t
SCRUBBER
CTi
TO
SOLIDS
CUNREACTED
ALUMINUM
OXIDE)
I
ALUMINUM
CHLORIDE
SOLUTION
i
FILTER
I
ALUMINUM
CHLORIDE
PRODUCT
i
PACKAGING
TO SALiS
-------
At Plant 19101 (producing both hydrous and anhydrous salts),
all plant waste water is treated by a caustic neutralization
and settling system before discharge. The treatment system
daily accommodates an average of 221 cubic meters (58,300
gallons) of waste water, which includes about 166 cubic
meters (43,900 gallons) of rainwater runoff. This system is
shown schematically in Figure 43, and effluent chemical data
supplied by the industry are presented in Table 20.
At Plant 19104, a lime neutralization system is employed to
treat process water from aluminum chloride production, as
well as from production of a number of other inorganic and
organic chemicals. This system is shown schematically in
Figure 44.
compatibility with POTWs
Discharges from aluminum chloride plants can contain enough
aluminum to cause problems in POTW. Aluminum is acceptable
in municipal treatment plants when it occurs at low
concentrations, but at high concentrations it can cause
excessive sludge bulking. At anhydrous aluminum plants
using scrap aluminum as a raw material, zinc can be present
in concentrations sufficient to inhibit POTW operation.
Some incidential removals of aluminum and zinc can be
expected in the POTW, but some of the aluminum and zinc, and
all of the chlorides present in the wastewater can be
expected to pass through the POTW. (See Table 21.).
Chloride discharges should pose no threat to the POTW
operation or the environment. Pretreatment may be
necessary, however, for reduction of aluminum and zinc
concentrations.
TYPICAL PRETREATMENT OPERATIONS FOR ALUMINUM SULFATE
SUBCATEGORY
Control
As discussed in Section V, aluminum sulfate manufacturing
processes differ slightly from facility to facility. All
process wastes are recycled at some plants. At Plant 19204,
clay has replaced bauxite as a raw material, with no effect
on process operations, and a closed-cycle waste stream has
been instituted to eliminate discharge. Fresh water is
introduced to the system through the wash tanks, as well as
through the digester. This system is shown in Figure 45.
At Plant 19205, aluminum sulfate is produced by dissolving
aluminum in sulfuric acid and precipitating the product from
the mother liquor. All water from the centrifuge is stored
and returned to the reactor. This system is shown in Figure
46. In addition, the Development Document for Effluent
163
-------
Figure 43. FLOW DIAGRAM SHOWING WASTEWATER TREATMENT USED IN
PRODUCTION OF ALUMINUM CHLORIDE (PLANT 19101)
COMBINED PLANT WASTEWATER
221 m3/day (58,300 gpd>
lay I
1
SODIUM
HYDROXIDE
SOLUTION
CAUSTIC
ADDITION
DRAINAGE
DITCH
SLUDGE TO LANDFILL
164
-------
TABLE 20. CHEMICAL COMPOSITION OF TREATED WASTEWATER FROM
PRODUCTION OF ALUMINUM CHLORIDE (PLANT 19101}*
PARAMETER
pH
TSS
Total Solids
BOD
COD
Ai
Ni
CONCENTRATION (mg/0*
DAILY AVERAGE
6to9f
38
30,000
20
113
13
1
DAILY MAXIMUM
8to9f
59
45,000
30
175
20
2
•Industry data.
tValue in pH units.
165
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Figure 44. FLOW DIAGRAM SHOWING WASTEWATER TREATMENT USED IN
PRODUCTION OF ALUMINUM CHLORIDE (PLANT 19104}
LIME STORAGE
I
en
WATER -*~
R AW WASTE
LIME SLURRY
SYSTEM
FIRST SETTLING
POND
SLUDGE TO
LANDFILL
(20% SOLIDS)
i
SECOND SETTLING
POND
DISCHARGE
UNDERFLOW
I
SOLIDS THICKENER
NOTE: THE SYSTEM DEPICTED TREATS WASTEWATER FROM
PRODUCTION OF ALUMINUM CHLORIDE, ALUMINUM
SULFATE. AMMONIUM THIOSULFATE, METYLAMINE SOLU-
TION, REAGENT-GRADE ACIDS, SODIUM BISULFITE SOLU-
TION, SULFAMIC ACID, AND SULFUR TRIOXIDE.
-------
TABLE 21. INCIDENTAL REMOVAL OF POLLUTANT PARAMETERS AT POTWs
PARAMETER
Ai
Cd
Cr (total)
Cu
Fe
Pb
Ni
Afl
Zn
Fluoride
PERCENT REMOVAL EFFICIENCY -
RANGE*
64
6-86
38-98
56-191
7S-97
31-95
0-61
60-73
45-96
6-16
NUMBER OF POTWs
1
16
20
21
11
17
17
3
19
3
* Based on data available from biological POTWs meeting secondary treatment
performance levels.
167
-------
Figure 45. FLOW DIAGRAM OF WASTEWATER-RECYCLING SYSTEM USED IN
PRODUCTION OF ALUMINUM SULFATE (PLANT 19204)
CLAY
7,700 kg
(17,000 Ib)
SULFURIC
ACID
9,100 kg
(20,000 lb>
WATER
SURERNATE
26m3
(6,800 gal)*
i
STORAGE TANKS
DIGESTER
SLURRY
i
SETTLING TANKS
MUD
LIQUID
i
WASH TANKS
WATiR
MUD
11m3
(3,000 gal)
LIQUID
t
SETTLING POND
*Wa$tewater net flows are given on a batch bails; makeup water requirements per
batch a approximately 26m3 (7,000 gal).
168
-------
Figure 46, FLOW DIAGRAM OF WASTEWATER-RECYCLING SYSTEM USED IN
PRODUCTION OF ALUMINUM SULFATE (PLANT 19205)
ALUMINUM
STEAM
SULFURIC
ACID '
WATER
WASH-WATER
STORAGE TANK
I
EAM
t I
ALUMINUM-
DISSOLVING
TANK
I
LIQUOR
t
COOLER
CENTRIFUGE
I
PRODUCT
SALTWATER FROM WELL
• COOLANT TO EVAPORATION POND
STORAGE
PACKAGING
TO SALES
169
-------
Limitations Guideline for the Major - Inorganic Chemicals
Industry describes two plants (therein, coded 019 and 063J
where zero discharge of process and cooling water is
practiced.
Pretreatment
Because there are no POTW dischargers in the aluminum
sulfate subeategory, there is no pretreatment technology
presently existing. This condition is probably largely
attributable to the fact that many aluminum sulfate plants
are zero dischargers for process waste water.
Only one discharging aluminum sulfate manufacturer was found
to be treating process wastes during this study. The
aluminum sulfate wastewater is mixed with many other waste
streams from a chemical complex and is lime-neutralized and
settled before discharge. Because the treatment system is
used for many products, no raw waste load or effluent data
are available. The treatment system is shown in Figure 44.
The Development Document for Effluent Limitations Guidelines
for the Inorganic Chemicals Industry states that current
typ'ical treatment for aluminum sulfate manufacturing
discharges involves use of a settling pond to remove muds,
followed by neutralization of residual sulfuric acid.
However, no specific plants were enumerated as practicing
this typical treatment.
Compatibility with POTWs
Raw wastewater from aluminum eulfate plants has been shown
to contain significant quantities of aluminum, zinc and
sulfate. Aluminum is acceptable in municipal treatment
plants when it occurs in low concentrations, but at high
concentrations it can cause sludge bulking. Zinc can be
present in concentrations sufficient to inhibit POTW
operation. Some incidential removals of aluminum and zinc
can be expected in the POTW, but significant amounts of
aluminum and zinc, and most of the sulfate present in the
wastewater will pass through the POTW. (See Table 21.)
Sulfate is not generally detrimental to POTW operation, and
should not pose significant environmental problems.
Pretreatment to reduce zinc levels is indicated.
TYPICAL PRETREATMENT OPERATIONS FOR CALCIOM CARBIDE
SUBCATEGORY
Control
170
-------
Most calcium carbide plants use dry dust collection,
Producers such as Plants 19301 and 19302 have dry systems
and, therefore, have no discharge except for occasional
noncontact cooling-water blowdown.
Pretreatment
The most reasonable pretreatment technology for calcium
carbide production employing a wet scrubber system is
settling. Varying retention times result in different
levels of treatment. Figure 47 diagrams the process and
treatment used at Plant 19303. Over 90S of the treated
scrubber effluent is recycled to the scrubber system at
Plant 19303.
It has been noted that settling can achieve as much as an
80% reduction in total suspended-solids concentration.
Plant 19303 reports an average suspended-solids
concentration of 40 mg/1 in the treated venturi-scrubber
effluent.
Compatibi 1 ity_ with POTWs
The wastes generated from calcium carbide production contain
moderate levels of suspended solids, and do not contain
other parameters that would be harmful to POTW operation or
to the environment. The suspended solids in this discharge
will be adequately removed by a POTW. Therefore, no
pretreatment of this waste is indicated.
TYPICAL PRETREATMENT OPERATIONS FOR CALCIUM CHLORIDE
SUBCATEGORY
Control
The effects of waste water control technology upon waste
volume reduction have been most pronounced at natural brine
Plant 19404. A number of process and noncontact water-use
changes have been institued which reduce the single waste
stream to a relatively low-volume, highly concentrated
waste. Well disposal of this 954-cubic-meter/day (0.252mgd)
waste brine solution to the originating geologic formation
has transformed the plant to zero-discharge status in terms
of process waste water being released to surface water.
P re tr ea tment ' ••
There is one POTW discharger in the calcium chloride
subcategory. The pretreated waste is discharged to a POTW
practicing primary settling. As described in Section V,
waste water from Plant 19406 is a result of emissions
171
-------
Figure 47. FLOW DIAGRAM FOR PRODUCTION OF CALCIUM CARBIDE {PLANT 193033
-si
ro
COKE
CRUSHER
DRYER
LIMESTONE-
CRUSHER
KILN
COOLER
*
AIR
WATER
VENTURI
SCRUBBER
SETTLING
POND
T
CARBIDE
FURNACE
90% RECYCLE OVERFLOW
DISCHARGE
COOLING
TOWER
WATER
PRODUCT
DISCHARGE
COOLER
I
CRUSHER
±
SCREENING
I
PACKAGING
f
TO SALES
DUST
COLLECTION
-------
control, which yields a waste containing hydrochloric aci<3.
As shown in Figure 18, the scrubber system receives waste
cooling water from other operations at the plant as makeup.
The scrubber water is combined with other chemical wastes
and neutralized before discharge.
As discussed in Section V, the Solvay process generates a
waste liquor with a daily volume ranging from 23,000 to
26,000 cubic meters (6 to 7 million gallons). At Plant
19101, roughly 25 to 30% of this liquor is routed to the
calcium chloride extraction circuit, and the resultant waste
from production of the salt is combined with the waste soda
ash liquor. Any calcium chloride process overflows due to
operational upsets are intercepted by plant sewers and
discharged to surface water. The combined soda ash and
calcium chloride waste streams are treated by settling and
subsequently discharged. The calcium chloride production
rate {at Plant 19401) is dependent upon local market
conditions, and the ratio of calcium chloride waste water to
soda ash waste water varies accordingly.
Plant 19112 produces the salt from pure calcium carbonate
and daily generates l cubic meter (300 gallons) of washdown.
The washdown is treated at a central facility, which
intercepts wastes from a number of reagent-grade chemical
processes. The system consists of multipoint pH
adjustments, multiple settling stages, flocculation, and
clarification. The final treated waste is discharged to a
river. The calcium chloride washdown waste contributes an
insignificant volume of water to the total treatment-plant
effluent.
Compatibility with POTWs
The waste streams generated from calcium chloride production
contain only calcium and sodium brines that will not
interfere with POTW operation. No pretreatment is
indicated.
TYPICAL PRETR1ATMENT OPERATIONS FOR COPPER (COPRIC) SULFATE
SUBCATEGORY
Control
The copper (cupric) sulfate manufacturing industry recycles
almost all process waters. Mother liquors and washdowns are
recycled to either the reactor tank or the crystallizer.
Reactor sludges may be sent to a nearby smelter for
precious-metal and copper recovery. The high value of
copper justifies recovery of most wastes and minimization of
the metal content of the water effluent. Noncontact cooling
173
-------
Figure 48. FLOW DIAGRAM SHOWING PRETREATMENT OF EMISSIONS • SCRUBBER
WATER USED IN PRODUCTION OF CALCIUM CHLORIDE (PLANT 19406)
WASTE COOLING
WATER
EMISSIONS-»»[§CRUBBER J-»r VENT
*iCf t*T"¥3 H f i"KeK| ^^^L^ COflff «3*f Iw 12 D VlrAS I ^S ^ROfW
NEyTRALIIE^f*^ CHEMICAL PRODUCTION
DISCHAROf TO
PUBLICLY OWNED
TREATMENT WORKS
174
-------
waters and eondensates present no difficulties to PQTW
operations and do not require pretreatment.
One type of waste water from copper sulfate production
potentially toad effects on POTW operations. The flow
resulting from plant spills and washdowns should be treated
before discharge to a PQTW.
Pretreatinent "
One of the plants studied for this document has a washdown
stream which is treated prior to discharge. The daily
washdown flow is approximately 20 to 22 cubic meters (5,000
to 6,000 gallons) at Plant 19505. The acidic waste water is
neutralized with'hydrated lime at a rate of 1,10 grams/liter
(10,000 pounds/millions gallons) of water treated. Figure
27 diagrams the treatment process at Plant 1950S,
The waste water mixture is settled in the neutralization
tank. The water is then decanted'to a filter press, and the
.sludge from the tank is put 'into a storage tank. Excess
water from the sludge storage tank is occasionally decanted
to the neutralization tank. The filter cake from the press •
is taken to the sludge storage tank, and the filtrate is
discharged. The thick sludges are deposited in a landfill.
Available data for the copper sulfate washdown effluent are;
Concentration (mg/1)
BeforeTreatment After Treatment
copper average: 433 average: 0.18
range: 0.1U to 1.25
nickel average; 159 average: less than 0.5
pH (not available) 7.3 to 11.1 (pH units)
Compatibility with PQTOs
The untreated wastewater from copper sulfate production can
contain levels of nickel and copper which exceed the limits
prescribed by most PGTW. (See Table 25.) High nickel and
copper levels may have a toxic effect on the biota of a
POTW. In addition, only incidental removal efficiencies
insufficient to achieve acceptable effluent quality can be
expected at the POTW. ^See Table 21.) Therefore,
pretreatment to reduce metal levels is indicated.
TYPICAL PRETREATMEMT OPERATIONS FOR IRON (FERRIC) CHLORIDE
SUBCATEGQRY
175
-------
general
Wastewater generated during ferric chloride production
includes: scrubber water, filter wash water, floor and
equipment washings, and leaks and spills. Recycle is
extensively used within the industry. Treatment is directed
toward metal removal and pH adjustment. The pretreatment
and control technologies used in the ferric chloride
industry are detailed below.
Control
The ferric chloride industry makes extensive use of recycle
to control process waste water. All of the waste water
generated contains ferrous or ferric chloride and, as such,
is a potential raw material. Impurities present in the
waste water do not affect its usefulness, since relatively
impure raw material, pickle liquor, is used to begin with.
To remove gross solids and to prevent the concentration of
impurities, Plants 19601 and 19602 settle the ferric
chloride process waste water prior to recycle.
In addition to recycling combined waste water back to the
process, several control technologies are employed for
individual waste streams:
Emissions-control scrubber water—Plant 19602 recyles
causticscrubber water generated from the control of process
tail gases. There is a small bleed stream, however, to
remove dissolved salts concentrated in the recycle stream.
Floor and equipment washings—The quantity of water used to
wash floors and process equipment varies significantly from
plant to plant. Plant 19601 daily uses « cubic meters (1000
gallons) of water for floor and equipment washings. Plant
19602, whose production is only one tenth of plant 19601,
daily generates 30 cubic meters (7,000 gallons) of waste
water. To a large extent, equipment type and process layout
govern the amount of washdown water required. However, good
housekeeping practices and conservative washdown techniques
can reduce water use.
Pretreatment
chemical precipitation, by pH adjustment and settling, is
the most common treatment technology employed within the
industry. It is illustrated in Figure **9. Either lime or
sodium hydroxide is used to form insoluble metal hydroxides;
the resultant floe is settled, and the supernatant is either
discharged or recycled. The qualities of ferric chloride
176
-------
Figure 49. FLOW DIAGRAM SHOWING TYPICAL WASTEWATER PRETREATMENT
USED IN PRODUCTION OF FERRIC CHLORIDE
WASTiWATER
SODIUM
HYDROXIDE
OR
LIME
MIX
TANK
SETTLING
TANK
DISCHARGE
SLUDGE
177
-------
which make it ideal as a precipitation agent in waste water
treatment also contribute to treatment of ferric chloride
process wastewater. The iron hydroxide forms a dense floe
which aids in the removal of other metals. Plant 19603
reports significant reductions in both total and hexavalent
chromium as a result of floe entrapment.
Removal efficiencies of iron approach 99%. The treated-
waste water characteristics from plants with and without
leaks and spills are presented in Table 22. High removal
efficiencies for other metals are also expected, due to the
presence in the waste water of large quantities of iron
floe, which will trap other metal hydroxides as it settles.
compatibility with POTWs
The wastewater generated from ferric chloride production
contains high concentrations of iron and the impurities
(chromium, copper, nickel, and zinc) contained in the pickle
liquor feed. Although iron is used for sludge conditioning
at some POTW, very high concentrations (1000 mg/1 and above)
may inhibit biological treatment operations. Much lower
concentrations of chromium, copper, nickel and zinc can
interfere with POTW operation. In addition, only incidental
removal efficiencies insufficient to achieve acceptable
effluent quality can be expected at the POTW. (See Table
21.) Therefore, pretreatment to reduce metal levels is
indicated,
TYPICAL PRETREATMENT OPERATIONS FOR LEAD MONOXIDE
SUBCATEGQRY
General
There are two significant sources of waste water in the lead
monoxide manufacturing industry: (a) washdown of equipment
and floors and (b) compressor blowdown, or water condensate
from air compressors. These two waste water sources are
discussed separately below.
Control
Plant Washdown. Ten out of eleven lead monoxide
manufacturing plants do not generate any washdown waste
water. These ten plants utilize dry vacuuming techniques
for dust control. Only one of the eleven plants produces a
washdown waste water.
Compressor slowdown. Compressor blowdown is an inherent
product of the air-compression process and cannot be reduced
through compressor modifications, or by recycling. However,
178
-------
TABLE 22. CHEMICAL COMPOSITIONS OF AVERAGE TREATED
WASTEWATERS FROM PRODUCTION OF FERRIC CHLORIDE
PARAMETER
TSS
Cr (total)
Cu
Fe
Pb
Mn
Ni
Zn
CONCENTRATION
-------
through the use of natural-draft furnaces, fans, or other
air-inducing equipment in the oxidation of lead to lead
monoxide, compressor condensate can be eliminated.
Pretreatment
Plant Washdown. Plant 19702 is the only lead monoxide plant
known to discharge process washdown. At Plant 19702, the
lead monoxide manufacturing process waste water is suaiped to
a small sedimentation pit, where the waste water is combined
with waste water from the manufacturing of other lead
chemicals. From the sedimentation pit, the combined waste-
water flows through an open ditch to a 0.3-hectare (0,75-
acre), unlined stabilization pond. The waste water from
manufacture of the other lead chemicals contains sulfate in
sufficient quantity to precipitate soluble lead as lead
sulfate.
The effluent from the stabilization lagoon flows to surface
water. Recently, a sand filter is believed to have been
added to the end of this treatment sequence for further lead
and suspended-solids removal. This treatment scheme is
illustrated in Figure 50.
Treatment accomplished in the stabilization lagoon is
reported to be 85 to 90% effective in reducing the lead
waste content. Further lead and suspended-solids removals
would be achieved by filtration. Laboratory tests using
filtration of settling-pond effluent indicate that total
lead concentrations are reduced by an additional 92%,
producing an effluent which contains a total lead
concentration of 0.058 mg/1. The effective overall lead
removal attained by this treatment approach is 98 to 99$.
At plants where a waste stream containing precipitation
agent such as a sulfate is not available, lime is generally
used to precipitate lead as lead hydroxide.
compressor slowdown. No lead monoxide plants are known to
employ pretreatment of compressor-blowdown waste water. As
indicated under "Compatibility with POTWs" below, there
appears to be little need for pretreatment of this waste
water.
CQmgatibility with POTW
The waste generated from lead monoxide production contains
lead and oil and grease. Oil and grease will be present in
small quantities and will be adequately treated and removed
by a POTW. Lead levels in the raw wastes, however, will
exceed the limits prescirbed by most POTW. (See Table 25.)
180
-------
Figure SO. FLOW DIAGRAM OF WASTEWATER-TREATMENT SYSTEM USED IN
PRODUCTION OF LEAD MONOXIDE (PLANT 19702)
NONCONTACT
COOLING WATER
WAStEWATiR FROM
MANUFACTUR OF
OTHf R LEAD CHEMICALS
00
WASTEWATiR
FROM W ASHDOWN
OF LEAD'
MONOXIDE PLANT
i
SUMP
PIT
COLLECTION
PIT
UNL1NED
STABILIZATION
LAGOON
SAND
FILTER
WASTEWATER
DISCHARGE
-------
TABLE 23. CHEMICAL COMPOSITIONS OF RAW AND TREATED WASTEWATERS
FROM PRODUCTION OF LEAD MONOXIDE (PLANT 19702)
PARAMETER
pH
TSS
Oil and Grease
Pb {total}
Chloride NS
SuIfateNS
CONCENTRATION (mg/l)
PRETREATMENT
INFLUENT*
•9.8ft
_
653«t/u
345
-
SETTLING-POND
EFFLUENT*
9.8™
30NPDES
0.49 est/c
0.9
345
31
PRETREATMENT
EFFLUENT AFTER
FILTRATION ••
9.8**-
024est/1
0.058
34F
-
'Combined waste stream from production of lead monoxide and other lead chemicals.
Average values based on company monitoring data for period 15 April 1973 through 1 July 1974 (30 grab
samples).
** Average values based on laboratory filtration tests conducted July 1973 through September 1973 {five
grab samples).
Value in pH units.
NPDES.
est/c
*NPDES discharge permit data.
Estimated value based on untreated eompressor-blowdown concentration given in Table V 10
and on a dilution factor of 4000.
est'' Estimated value based on same removal efficiency (92%) attained for lead in laboratory filtration test.
Estimated values based on untreated washdown pollutant concentration given in Table V-9 and on a
dilution factor of 1.52.
Not considered significant components of lead monoxide process waste water.
NS
182
-------
Lead is recognized as being toxic to fish and wildlife and
to humans. In addition, only incidental removal
efficiencies insufficient to achieve acceptable effluent
quality can be expected at the POTW. (See Table 21.)
Therefore, pretreatment to reduce lead levels is indicated.
TYPICAL PRETREATMSNT OPERATIONS FOR NICKEL SOLFATE
SDBCATEGORY
General
Wastewater generated during nickel sulfate production
includes: plating solution treatment filtrates; emissions-
control scrubber water; filter sludges and washwater;
miscellaneous equipment and floor washings; and leaks and
spills.
Control
Plating-Solution Treatment Filtrate. ' 'Plating-solution
treatment filtrate offers very little potential for reuse or
recycle. The gross impurities present make it unamenable
for recycle to other operations within the process. Thus,
Plant 19803, which makes extensive use of recycle within its
process, discharges the waste filtrate from the spent
plating solution treatment operation.
Emissions-Control Scrubber Water. Scrubber water at Plant
19801 is collected in a baffled tank, to facilitate settling
of suspended solids, and then recycled. However, about 10%
of the scrubber water must be bled off to remove dissolved
salts, concentrated in the recycle stream. Other nickel
sulfate manufacturers, apparently, have no need for process
emissions control and, therefore, do not employ wet
scrubbers,
Filter Sludges and Wash Water. Depending on the removal
techniques employed, the volume and characteristics of waste
water generated from washing caked material from filters can
be quite variable. Large volumes of waste water, high in
suspended solids, are generated if the filters are merely
washed of caked material. Suspended solids levels can
approach 15%. However, the use of mechanical scrapers to
remove caked material can eliminate this waste water
altogether; producing a solid waste instead.
The efficiency of the mechanical scraping device greatly
influences waste water reduction. Plant 19803 reports only
sludge production, with no waste water generated from filter
cleaning. Plant 19801, on the other hand, daily generates
183
-------
189 liters (50 gallons) of wastewater, due to the need for a
final rinse to remove filter residues left after scraping,
Egolgnrent. and Floor 'Washings.. Equipment and floor washings
contain large quantities of raw materials and product.
However, they .also contain dust, grease, and other
impurities that are found in the plaint environment. At
plants where relatively impure raw materials are .handled
routinely, these washings can be recycled back to the
process for additional product recovery. Those plants, such
as Plant 19801, which use pure nickel oxide" "as a starting
material and, therefore, do not have purification processes,
may not be able to recycle equipment and floor washings
without installing purification eguipment or practicing
stringent product-loss control. If not recycled, these
wastes would require treatment.
Because these wastes are high in suspended solids, there is
little potential for their use elsewhere in the plant for
cooling, gas scrubbing, etc.
Fgetreatirtent
In general, waste streams from nickel sulfate production are
combined prior to pretreatment and discharge to POTWs.
Because these wastes are chemically similar, combined
pretreatment offers many practical and economic advantages.
Plant 19601 employs metal precipitation by pH adjustment
(with sodium hydroxide) and settling before discharging the
treated waste water to the sewer. Figure 51 illustrates
this pretreatment scheme. Plant 19803 also uses sodium
hydroxide to precipitate metals. However, in this case, the
waste water is directed to a sand ,filter for suspended-
solids removal. This treatment technology is illustrated in
Figure 52,.
Nickel removal efficiencies of only 50% are experienced at
Plant 19801. At Plant 19803, 79% nickel removal efficiency
is achieved. The inability of simple gravity settling to
remove nickel is probably due to the low density of the
nickel hydroxide floe formed. Sand filtration offers a more
effective technique for removal of low-density suspended
materials. The chemical characteristics of treated waste
water discharged from Plants 19801 and 19803 are presented
in Table 2H.
The most practical and cost-effective techniques for
pretreatment of nickel sulfate waste water may b& chemical
precipitation, gravity settling of gross suspended solids,
and effluent polishing by sand filtration. This approach
-------
Figure 51. FLOW DIAGRAM SHOWING WASTEWATER PRETREATMENT USED IN
PRODUCTION OF NICKEL SULFATE (PLANT 1S80!)
WAST1WATER
SODIUM
HYDROXIDE
DISCHARGE
MIX
TANK
SETTLING
TANK !
SLUDGE
185
-------
Figure S2. FLOW DIAGRAM SHOWING WASTEWATER PRETREATMENT USED IN
PRODUCTION OF NICKEL SULFATE (PLANT 19803)
BACKWASH
SLUDGE
WASTEWATER
HV
SODIUM I
'DROXIDE
* 1
MIX
TANK
•*-
I
j
SAND
FILTER
t
DISCHARGE
4
1
I
BACKWASH
186
-------
TABLE 24. CHEMICAL COMPOSITIONS OF TREATED WASTEWATERS
FROM PRODUCTION OF NICKEL SULFATE {TWO PLANTS)
PARAMETER
PH
TSS
Ni
CONCENTRATION
(mg/IJ
PLANT 19801
8.0*
30
180
PLANT 19803
10.2*
_
3.0 '
*Value in pH units.
187
-------
takes advantage of the relatively low cost of gravity
settling and of the enhanced settling due to synergistie
effects of other materials present in the waste water. At
the same time, it makes use of the sand filter's ability to
remove unsettleable suspended solids without the need for
frequent backwashings to remove large quantities of solids.
This treatment system is illustrated in Figure 52.
Compatibility with POTW
The various waste streams generated from nickel sulfate
production contain levels of nickel—and, in some cases,
copper—which exceed the limits prescribed by most POTws,
(See Table 25.) Nickel concentrations in the combined waste
water discharged from nickel sulfate manufacturing plants,
in general, range from 12 to 360 mg/1 Ni. Copper levels in
waste water discharged to POTWs range from 5 to 70 mg/1.
These levels of nickel and copper may have a toxic effect on
the biota of a POTW. In addition, only incidental removal
efficiencies insufficient to achieve acceptable effluent
quality can be expected at the POTW (Reference 17}.
Therefore, pretreatment to reduce metal levels is indicated.
TYPICAL PRETRSRTMENT OPERATIONS FOR NITROGEN AND OXYGEN
SUBCATEGORY
Control •
Although the basic single process of air separation for the
production of nitrogen and oxygen remains the same, various
technological modifications have already enhanced the
associated control practices with regard to certain process
waste waters. Modern air-separation plants—particularly,
those built within the last 15 years—have specified the
installation of minimal-oil or oil-free type compressors.
This modification has eliminated the gross production of
oily compressor condensate common to the older,
reciprocating-type compressors.
In addition, the use of caustic-scrubber solutions has been
diminished as a result of the development of a system of
reversing exchangers for the removal of carbon dioxide
impurities. In this system, carbon dioxide and water vapor,
which enter under high pressure, are condensed, then
evaporated and purged from the system by low-pressure
nitrogen. This technology has served to eliminate the
production of a caustic wastestream.
With regard to possible water reuse in the process, recycle
of any condensate water is precluded by the presence of oil
188
-------
TABLE 25. EFFLUENT LIMITATIONS IMPOSED BY PUBLICLY
OWNED TREATMENT WORKS (POTWs)
PARAMETER
pH
TSS
Oil and Grease
Al
As
Ba
Cd
Cr (total)
Cr (hexavalent)
Cu
Fa
Pb
Hg
Ni
Ag
Zn
Fluoride
CONCENTRATION RANGE
(mg/l)
4.S-11.0
250-1,500
100-600
40-800
0.1-3.0
1.0-15
0.2-15
0.75 - 25
0.1 -10
0.2-17
4,0-100
0.1 - 5.0
0,0005 - 0.3
0.2 - 10
0.2 - 5.0
1.0-16.5
2.5 60
•Value in pH units.
189
-------
and grease, which, if returned to the system, would -tend to
foul the heat exchangers.
Finally, note that many air-separation plants have opted to
utilize biodegradable corrosion inhibitors for cooling water
when possible.
Pretreatment
The use of pretreatment technology has been employed by the
nitrogen and oxygen manufacturing industry to some degree
since the inception of the industrial process of air
separation. The level of treatment has been dependent on
both the volume and waste characteristics of the process
waters produced. Oily compressor condensate has been, and
continues to be, the only significant process contact water
produced which may be part of the total plant discharge.
Most manufacturers, however, do not consider this to be a
major problem in plant operation. Early efforts were made
to physically contain the process water in a holding pond or
ditch. Some plants employed a slightly more advanced
technology using oil skimmers or weirs and dams, in
conjunction with holding ponds, to separate the oil/water
mixture. This produced a more acceptable effluent. In
fact, various modifications of this type of oil separation
still constitute the most widely practiced technology. Oil
emulsifiers and coalescers are also utilized to some extent
as a means to treat oily wastes,
In most contemporary air-separation plants, the flow of oily
condensate waste water appears to be a major determining
factor in the type of waste treatment employed. For
example, Plant 13103 produces only about 1.5 liters (2.0
gallons) of compressor condensate per day. This small
volume is easily handled, and the treatment consists of
completely collecting the waste stream in large drums, which
are removed once a month by a contractor.
Plant 13102 discharges directly to a surface stream and
employs an oil separator consisting of a series of holding
ponds with oil skimmers. The daily average flow, as
indicated in Figure S3 is approximately 3.78 cubic meters
(1,000 gallons). The treated effluent is discharged
separately from the cooling-tower blowdown (although, in
many plants, it is common practice to combine the two
streams prior to discharge). The oil and grease
concentration of the separator effluent ranges from 10 to 15
mg/1, which is well below any potentially harmful
concentration for this pollutant. This effluent would be
considered acceptable for either direct or indirect
discharge.
190
-------
Figure 53. FLOW DIAGRAM SHOWING PRETREATMENT OF WASTEWATER IN
PRODUCTION OF NITROGEN AND OXYGEN (PLANT 13101}
FLOOR
WASHINGS
LEAKS AND
SPILLS
i
AIR
COMPRESSOR
-CONDENSATE-
COLLECTION
SUMP
AVERAGE
FLOW
' 3.78 eu m/day"
(1000 gal/day)
OIL SEPARATOR
OR
COALESCER
FINAL
DISCHARGE
(002)
VO
COOLING
SYSTEM
COOLING
TOWERS
SLOWDOWN
_AVERAGE FLOW.
7570 cu m/day
(2,000,000 gal/day)
FINAL
-^•DISCHARGE
(001)
-------
Plant 13101 is currently discharging to a POTW and producing
an effluent with an average oil and grease concentration of
9.0 mg/1. The type of pretreatment system employed by this
plant is representative of another type of oil separator. A
£low diagram for this treatment system is given in Figure
54. The average daily flow handled by this system is
approximately 22.5 cubic meters (5,950 gallons), but this
can vary considerably over a 48-hour period, depending on
chemical production and relative air humidity. The
compressor condensate is contained in a central sump area,
along with small volumes of equipment washdowns. This waste
water is periodically pumped to one of two oilseparator
holding tanks, which operate alternately. A chemical
addition takes place when the terminal tank volume is
reached. After a period of physical agitation, the tank
contents are allowed to settle quiescently. The separated
oil layer is skimmed off after approximately 3 hours of
settling, and the treated effluent is drained from the tank
and directed to the cooling-water discharge leaving the
plant. The collected oil is placed in a large drum, which
is periodically removed by a contractor,
An analysis of the efficiency of the treatment system is
given in Table 26, Note that the effluent pH indicated is
abnormally high, due to a miscalculation of the amount of
caustic added on the day the sample was taken. Caustic is
normally added to adjust the pH of the system after the
initial addition of the acidic chemicals.
CQJlBatibil it y_ with POTW
The wastewater generated from production of nitrogen and
oxygen contains oil and grease from compressor condensate.
The flows are generally small (from 1000 to 7000 gallons per
day) and the amounts of oil and grease discharged will not
interfere with POTW operation, and will be adequately
removed by the POT«. No pretreatavent is indicated.
TYPICAL PRETREATMENT OPERATIONS FOR POTASSIUM BICHROMATE
SOBCATE6O1Y
Control
AS 'discussed previously in Section ¥, the manufacturing
process employed at the single known plant in this
subcategory does not generate a wastewater discharge. Water
used in the process is either consumed by evaporation or
recycled as steam condensate. Information concerning the
reason for this recycle is not available.
192
-------
Figure 54. FLOW DIAGRAM OF OJL-SEPARATION PROCESS FOR TREATMENT OF
COMPRESSOR-COMPENSATE WASTEWATER IN PRODUCTION OF
NITROGEN AND OXYGEN {PLANT 13101)
COLLECTED
COMPRESSOR
CONDENSATE
FLOOR
WASHINGS—1
to
CO
±
CHEMICAL
ADDITION
OIL-SEPARATION TANKS
(USED ALTERNATELY)
WASTEWATER
STREAM
_ |
i^SPILLS
f
COLLECTION
SUMP
AVERAGE FLOW
22.5 m3/OAY
(5,960 gal/DAY)
CHEMICAL
ADDITION
WATER
INLET
(FOR SECOND
TANK)
WATER INLET FOR
ADJUSTING LEVEL
OF WASTEWATER
FTREATED
EFFLUENT
TREATED
EFFLUENT
(JOINS TOTAL
PLANT DISCHARGE)
OIL STORAl"! TANK
{OIL PERIODICALLY REMOVED BY CONTRACTOR)
-------
TABLE 26. CHEMICAL COMPOSITIONS OF AND WASTE LOADINGS FOR COMPRESSOR-COMPENSATE
WASTE WATER FROM PRODUCTION OF NITROGEN AND OXYGEN BEFORE AND AFTER
TREATMENT BY OIL-SEPARATION PROCESS (PLANT 13101)
PARAMETER
pH
IDS
TSS
Oil and Grease
Cd
Cr (total)
Cu
Pb
Hg
Zn
OIL-SEPARATOR INFLUENT"
CONCENTRATION
(ppm}
6.4«*
560
780
1,960
<0.01
0.85
0.48
<0.02
< 0.0002
0.34
WASTE LOAD
' kg/1000 metric tons
^.
24
33
84
< 0.00043
0.036
0.021
< 0.00086
< 0.00001
0.01S
)b/1 000 short tons
—
48
ee
168
< 0.00086
0.072
0,042
< 0.0017
< 0.00002
0.030
OIL-SEPARATOR EFFLUENT*
CONCENTRATION
(ppml
11.4**
1,400
22
9.0
<0.01
0.81
<0.02
<0.02
< 0.0002
0.02
WASTE LOAD
kg/1000 metric tons
58
0.94
0.38
< 0.00043
0.03S
< 0.00086
< 0.00086
< 0.00001
0.00086
fb/TOOO short tons
_
116
1.88
0.76
< 0.00086
0.070
< 0.0017
< 0.0017
< 0.00002
0.0017
•Analyse* based on composite of four individual grab samples taken over 8-hour period.
t Analyses based on single grab sample taken approximately 4 hours offer initiation of treatment.
••Value in pH units.
-------
If water is used at this plant for cleanup of spills or
equipment, good housekeeping measures could be employed to
reduce the volume of water required for these purposes.
Such housekeeping measures would essentially be spill
prevention precautions.
In the past, water used for cooling during the vacuum
crystallization step of this process was contaminated with
chromium. Plant officials reportedly planned to correct
this problem during 1975 through the replacement of a
barometric condenser with a noncontaet heat exchanger,
Pr etr eatment
No known process-related waste water is present at Plant
19901. Assuming that the barometric condenser mentioned
previously has been replaced with a heat exchanger the
cooling water should no longer be contaminated with
chromium. This being the case, this cooling water should
require no treatment prior to discharge.
However, it is possible that water is used at this plant for
the purpose of equipment washdowns and cleanup of spills.
Should this be the case, it is likely that this water would
be contaminated to a significant extent. Although the
volume or character of such waste water is unknown it is
expected that chrome would be the waste parameter of primary
concern. In this case, it is possible that an applicable
removal technology would be, reduction of hexavalent chromium
with sulfur dioxide (SO2) followed by lime precipitation of
trivalent chromium.
Compatabjlity with 'POTW
The wastes generated from potassium dichromate production
could be contaminated by chromium, which in its hexavalent
state is soluble and extremely toxic to biological treatment
plant biota and to higher life forms. In addition, only
incidental removal efficiencies insufficient to achieve
effluent quality can be expected at the POTW. (see Table
21.) Therefore, pretreatment for control of chromium is
indicated.
TYPICAL PRETRBATMENT OPERATIONS FOR POTASSIUM IODIDE
SOBCATEGORY
Control
In this industry, waste water originates primarily as
equipment and floor washdown and from the cleanup of spills.
195
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Control measures applicable to these waste waters include
simply good housekeeping and spill prevention precautions.
An in-process control measure is indicated in Figures 16,
17, and 18. This consists of mother liquor recycle for the
purpose of recovering residual product values. Because
waste solids generated in the manufacturing processes
employed in this industry are typically landfilled, the
practice of recycle of mother liquor results in no discharge
of wastewater directly from these processes. The single
exception is Plant 20103 which reportedly slurries the waste
solids and discharges this slurry to a POTW.
Pretreatment
Presently, only two of the four plants comprising this
industry subcategory (Plants 20102 and 20103} discharge to
POTWs. Neither of these plants practices pretreatment of
its waste water prior to discharge. One of the two plants
not discharging to a POTW (Plant 20101} is located on the
West Coast and achieves zero discharge by use of an
evaporation pond. The other plant (Plant 20104} treats
waste water originating from a multitude of chemical
manufacturing processes in a single, central treatment
facility. The treatment technology employed includes pa
adjustment, flocculation, and clarification.
As discussed previously in Section V, waste water generated
in this industry subcategory includes equipment and floor
washdown and cleanup of spills. Once-through, noncontact
cooling water is also discharged. Plant 20102 daily
discharges to a POTW an average of 32.6 cubic meters (8,600
gallons) of water used for noncontact cooling. With the
exception of an elevation in temperature, the character of
this water is expected to change little. POTWs which have
established .temperature requirements for waste waters
received from industry have generally indicated a tempera-
ture limitation of 66 °C (150°F). It is not expected that
cooling water used once and discharged will approach or
exceed this temperature.
At all plants in this industry subcategory, small quantities
of water are used to clean up product or reagent spills and
to wash down equipment, etc. Water used for these purposes
will vary in degree of contamination. Raw materials and
process products which such water will most likely contact
at some time include: potassium iodide, potassium iodate,
potassium hydroxide, potassium carbonate, and iron powder.
Of these, the potassium hydroxide (a strong base) is of
greatest concern from the viewpoint of compatibility with a
POTW operation. Limitations established by POTWs require
196
-------
the pH of water received from industry to be within the
range of 6.0 to 9,0 in most instances and, in some
instances, 5.5 to 10.5, Control of pH by use of
neutralizing agents is a well-known technology. Such
technology can be reasonably applied should pH of the waste
water exceed the limits imposed by a POTW. However, in view
of the small volumes of water being discharged, it is
expected that the most effective and most economically
desirable alternative is simply spill prevention and good
housekeeping measures.
CpmpatabilitY with POTW
Discharge from potassium iodide production generally consist
solely of non-contact cooling water, and extremely small
quantities of water used for equipment washdown or cleanup
of spills. The wastes will not adversely affect POTW
performance, and any pollutants picked up during the
washdown process (oil and grease, suspended solids) will
receive adequate treatment in the POTW. Therefore, no
pretreatment is indicated.
TYPICAL PRETREATMENT OPERATIONS FOR SILVER NITRATE
SPBCATEGORY
General'
Wastewater generated during silver nitrate production
includes: evaporator condensate, chemical-purification
waste water, NOx emissions-control scrubber water, and floor
and equipment wash water. These waste streams are combined
and sent to a silver-recovery unit, where 99+% of the silver
present in the waste water is removed. The resultant waste
water is discharged to a treatment system.
Control
The silver nitrate production industry makes great use of
recycling as a way to recover quantities of valuable silver
and as a waste water control technology. Plant 20201
recycles evaporator condensate back to the nitric acid
recovery unit. In addition, large quantities of noncontact
condensate are used in the operation of boilers and
turbines. Plant 20202 recycles centrifuge washwater back to
the filtration step to recover additional silver nitrate.
Neither Plant 20201 nor Plant 20202 recyles equipment and
floor washings back to the process. These washings are
undoubtedly high in suspended solids, and the potential for
recyle within the process without some settling is doubtful.
Both plants direct these waste streams to silver recovery
197
-------
units, thus reducing pollutant loads without reducing waste-
water volume.
Pretreatment
Plant 20201 combines the waste water from the silver-
recovery unit with waste water from other inorganic-chemical
processes, with sanitary wastes, and with storm runoff.
These combined waste streams are then directed to the
company's industrial waste water-treatment plant. The
treatment plant is a biological-treatment system consisting
of primary clarification, neutralization, an activated-
sludge process, trickling filters, secondary clarification,
and chlorination.
Highly toxic levels of silver are present in the waste water
generated during silver nitrate production. However, the
concentration of silver is reduced by a factor of 1000 due
to dilution by other streams entering the treatment system.
This dilution allows large quantities of silver to enter the
treatment plant without creating adverse effects on the
biota.
The chemical characteristics of the discharge from Plant
20201*3 biological-treatment system are presented in Table
27. Note that significant reductions in metals are shown.
The waste water generated from silver nitrate production by
itself is not amenable to biological treatment. In
addition, significant removal of metals cannot be predicted
from a biological-treatment system. Therefore, use of more
conventional physical/chemical pretreatment technology is
recommended. Figure 55 illustrates a batch pretreatment
system.
Lime is added to form insoluble hydroxides, and
polyelectrolyte is added to enhance flocculation. The
resultant slurry is fed to a plate and-frame filter press to
remove suspended material. Filtrate is recycled until the
desired effluent quality is achieved and then discharged.
Sludge is removed from the filter and landfilled.
Compatibility with POTW
The waste streams generated from silver nitrate production
can contain silver in quantities which exceed the quantities
prescribed by most treatment plants. (See Table 25.)
Silver in concentrations greater than 5 mg/1 will inhibit
biological treatment processes. In addition, only
incidental removal efficiencies insufficient to achieve
acceptable effluent quality can be expected at the POTw.
198
-------
TABLE 27. CHEMICAL COMPOSITION OF TREATED WASTEWATER
DISCHARGED FROM PRODUCTION OF SILVER NITRATE
(PLANT 20201)
PARAMETER
pH
TSS
Ag
Ba
Cd
Cu
Fe
Pb
Mn
Hg
Nt
Zn
CONCENTRATION
Cms/U
7.1*
70
0.15
0.90
0.19
0,11
1.7
0.16
1.2
< 0.0001
0.11
1.0
"Value in pH units.
199
-------
Figure 55. FLOW DIAGRAM SHOWING WASTEWATER PRETREATMENT USED IN
PRODUCTION OF SILVER NITRATE (PLANT 20201)
WASTEWATER
POLYiLECTROLYTE
LIME
T H
MIX
TANK
*~
|
RECYCLE
TAWK
— r
•*•
FILTER
DISCHARGE
SLUDGE
200
-------
{See Table 21.) Therefore, pretreatment to reduce silver
concentrations is indicated.
TYPICAL PRETREATMENT OPERATIONS FOR SODIUM BICARBOHATE
SUBCATEGORY
general
As discussed in Section V of this document, there are
several sources of process waste water from the manufacture
of sodium bicarbonate. Control and pretreatment
technologies employed within the industry are discussed
below for the following process waste water:
(a) Recycle-liquor overflow
(b) Filter backwash
(c) Spills, leaks, and washdowns
Of these, recycle-liquor overflow (the combined waste water
generated from slurry-thickener overflow and dryer
emissions-control scurbber water) is the most significant
from the standpoint of pretreatment in the sodium
bicarbonate industry.. The volume and pollutant content of
this process waste water far exceed those of other process-
waste water sources for the industry.
Little information on waste water generated from the
cleaning of filter media during backwash is available for
the sodium bicarbonate industry. Observations made in this
section on this waste water source are based upon the
general nature of the waste water.
Wastewater generated from the spillage and leakage of raw
materials and product from the sodium bicarbonate
manufacturing process is not considered to be a major
problem.
The discussions which follow treat, in turn, each of the
waste water sources tabulated above.
Control
Recycle- Li gj ugr overflow. One of the three sodium
bicarbonate producers has achieved zero discharge of sodium
bicarbonate process waste water through impoundment. This
facility. Plant 12103, has a favorable water balance, which
allows sufficient evaporation to occur during waste water
impoundment.
One plant presently plans to use slurry-thickener overflow
as a source of liquid for the product-dryer scrubber.
201
-------
Recycling this liquid to concentrate it with respect, to
sodium carbonate will enable it to be reused in the process.
These process changes will eliminate the discharge of
process waste water.
Filter Backwash. The purpose of filtration is to physically
remove particulate matter from solution, and the purpose of
backwashing the filter is to remove the accumulated
particulate matter from the filter. Thus, the resulting
backwash waste water contains large amounts of suspended
solids. To recycle or reuse this water, the solids must be
settled. The amount of use this control technique receives
within the sodium bicarbonate industry is not known at this
time.
Spills, LeakSj. and Washdowns. Plants 12101, 12102, and
12103 all pr-oduce a refined, food-grade sodium bicarbonate
product. It is mandatory for such facilities to employ good
housekeeping procedures and thereby keep the quantity of
this waste water small.
Prgtreatme nt
R ecycle-Liquor Overflow. Plants 12101 and 12102 are
presently treating process waste waters by settling prior to
discharge to surface water bodies. Untreated slurry-
thickener overflow is combined with waste water from other
segments of the complex in the settling basin. The degree
of treatment achieved at these plants is shown in Table 28.
Both plants claim 99+% suspended-solids removals in their
settling ponds, and Plant 12102 is aiming for a residual TSS
concentration of 15 mg/1 by the use of polyelectrolytes as
settling aids.
Filter Backwash. Plant 12101 presently combines filter-
backwash water with other sodium bicarbonate process waste
water and discharges these wastes to a settling basin prior
to discharge to a surface water body. Total suspended-
solids removals of 99+1 in the settling basin are claimed.
Similar TSS removal efficiencies are reported at Plant
12102.
Spills, Leaks, and Washdowns. Plants 12101 and 12102
presently combine this waste water with other wastes
generated within the complexes and settle the combined waste
stream prior to discharge. Suspended solids, which are the
major constituent of this waste water, are removed to a
large degree in the settling basins.
202
-------
TABLE 28. EFFECTS OF TREATING WASTEWATER BY SETTLING IN PRODUCTION
OFSODJUM BICARBONATE (PLANTS 12101 AND 12102)
PARAMETER
pH
TSS
TDS
RANGE OF CONCENTRATION (mg/l)
IN SETTLING-POND OVERFLOW
Plant 121Q1«
10.6 to II*1"
26 to 1,784
34,227 to 87,046
Plant 121 02
20 to 30
•Company monthly monitoring data for period November 1972
through April 1973.
'Value in pH units.
203
-------
Plant 12103 presently discharges plant runoff directly to a
surface water body.
Compatibility with POTW
The various waste streams generated from sodium bicarbonate
production contain high levels of suspended solids (TSS) and
dissolved solids (IDS) . The wastes do not contain any
substances -which would be likely to upset POTW performance.
Suspended solids would receive adequate treatment in a POTW.
The dissolved solids would pass through a POTW without
treatment. There is, however, no existing practicable
technology for TDS removal, and the TDS in question pose no
hazard to the environment. Pretreatment for this
subcategory is not indicated.
TYPICAL PRETREATMSMT OPERATIONS FOR SODIPM FLUORIDE
SPBCATEGORY
General
There are several sources of process waste water in the
sodium fluoride manufacturing industry, inluding:
separated silicate liquor,
clarifier supernatant,
scrubber blowdown ,
washdown .
All of these sources may produce a waste water containing
varying amounts of fluoride, suspended solids, and dissolved
solids at different pHs. Consequently, it is more
advantagepus to combine these process waste water streams
and treat them simultaneously rather than to treat each of
the individual process waste water streams for the removal
of the same pollutants, control and treatment technologies
employed by potential POTW dischargers are essentially the
same for all process waste streams, and the discussion which
follows centers around the removal or reduction of selected
pollutant parameters from the process waste water as a
whole.
From a pretreatment standpoint, the single most important
pollutant present in process waste water from the
manufacture of sodium fluoride is fluoride ion. It is
incompatible with the operation of a POTW at the
concentrations found in untreated process waste effluent.
20*
-------
Control
Two of the three sodium fluoride producers have achieved
zero discharge of fluoride-containing process waste water
through the use of water recycle. Depending upon the
manufacturing process employed and the chemical
characteristics of the process waste water to be recycled,
treatment may or may not be required prior to reuse of the
water.
The manufacturing process employed at Plant 20301 is such
that the process waste water is actually unreacted raw
material in solution. This process waste stream is fairly
homogeneous and can simply be recycled to the reactor
without treatment.
Plant 20302 employs a different manufacturing process9 using
caustic soda and sodium silicofluoride as raw materials.
The process waste water at this plant consists of separated
silicate liquor, which is not a desirable input to the batch
reactor and cannot be recycled without treatment.
Therefore, this process waste stream is combined with other
plant wastes and piped to a solids-retention pond, where
neutralization and sedimentation occur. The plant has
recently installed a su-rge pond to retain the solids-
retention pond runoff during heavy rains. Effluent from the
surge pond is recycled to the plant complex. A treatment
system flow diagram for Plant 20302 is shown as Figure 56.
Pretreatment
Plant 20303 is the only sodium fluoride manufacturer
characterized which is not achieving zero discharge of
sodium fluoride process waste water. At Plant 20303,
untreated sodium fluoride process waste water is combined
with the waste streams from the manufacture of various other
inorganic and organic chemicals. This combined waste water
is treated at a central treatment facility. The treatment
facility is basically a lime-precipitation, flocculation,
and sedimentation operation employing aeration, partial
recirculation, and multiple pH adjustment. A simplified
flow schematic of the central waste water treatment facility
at Plant 20303 is shown as Figure 57. The Qegreee of
treatment achieved at this plant is enumerated in Table 29.
The treatment-plant effluent is of neutral pH, with a low
residual TSS content. The total dissolved-solids content of
the combined waste stream remains nearly unchanged in
passing through the treatment sequence. Fluoride effluent
concentrations of 20 mg/1 have been reported using lime
treatment.
205
-------
Figure 56. FLOW DIAGRAM OF WASTEWATER-TREATMENT SYSTEM USED
IN PRODUCTION OF SODIUM FLUORIDE (PLANT 20302)
INFLUENT WASTEWATER
FROM NaF PROCESS
INFLUENT WASTEWATER
FROM OTHER OPERATIONS
IN PLANT COMPLEX
SOLIDS-
RETENTION
POND
RECYCLE WATER TO
PLANT COMPLEX
PRECIPITATION
AGENT
POND
RUNOFF
SURGE
POND
RECYCLE WATER TO
PLANT COMPLEX
206
-------
Figure 57. FLOW DIAGRAM OF CENTRAL WASTEWATER-TREATMENT SYSTEM USED
IN PRODUCTION OF SODIUM FLUORIDE (PLANT 20303)
ro
o
RECIRCULATION-
T
COMBINED UNTREATED
WASTEWATER INFLUEN
CHLORINATOR
H
PARSHALL
FLUME
LIME
SLURRY
EQUALIZATION
LAGOON
M
i
FLOCCULATOR
FLASH
MIX BASIN
AIR
INTAKE
COMPRESSED
AIR
PRIMARY WASTEWATER FLOW
ALTERNATIVE WASTEWATER FLOW
RECIRCULAT10N/RECYCLE, AIR FLOW, REAGENT PATH
RECYCLE
-TO UNTREATED
INFLUENT
AERATION
BASIN (SPARES)
FLOCCULATOR
BASIN
VALVE
EFFLUENT
TO RIVER
ACID FLASH
MIX BASIN
-------
TABLE 29. CHEMICAL COMPOSITIONS OF RAW
AND TREATED WASTEWATERS FROM
PRODUCTION OF SODIUM FLUORIDE
AND OTHER CHEMICALS (PLANT 20303)
PARAMETER
PH
TDS
TSS
Fluoride
CONCENTRATION (mg/!»*
INFLUENT
6.2*
870
36
N/A
EFFLUENT
7.1*
900
8.7
N/A
* Combined wastewater influent from production of sodium fluoride and
numerous other inorganic and organic chemicals; average values based on
company monitoring data.
Value 'm pH units.
N/A Data not available.
208
-------
Comparative laboratory and pilot-plant tests have shown that
the use of calcium chloride with lime may have advantages
over classic lime treatment (Beference 16).
Residual fluoride concentrations after lime treatment
mainly dependent upon:
(1) maintenance of high soluble calcium-ion concentrations
at pH 11 to 12 or higher,
(2) long retention times of precipitated calcium fluoride
to encourage postprecipitation, and
(3) exlusion of interfering ions.
Both methods of treatment depend upon the availability of
soluble calcium ion when either lime or lime and calcium
chloride are fed to fluoride-bearing waste water streams.
Insoluble calcium fluoride that is precipitated can be
separated by sedimentation, filtration, or combinations of
the two. The reaction is: .
2F- + Ca++ • = CaF2.
The solubility product of calcium fluoride at 18°C (6fl°F)
suggests that residual fluoride levels of 7,8 mg/1 may be
attained.
The solubility of calcium hydroxide at 20°C (68°F) is 1.69
g/1, compared to the higher solubility of calcium chloride
of 745 g/1 at 20°C. The theory is that the more soluble
calcium chloride provides higher soluble calcium-ion
concentrations than lime alone and that, therefore, lower
residual fluoride concentrations will result. At the
time, by using lime with calcium chloride, rather than
calcium chloride alone, costs can be reduced, since calcium
chloride is the more expensive of the two reagents,
Compatibility with POTW
Wastewater generated from the production of sodium fluoride
can ,contain concentrations of fluoride which exceed the
limits prescribed by most POTW, (See Table 25.) Fluoride
concentrations in raw process water of 16000 .mg/1 have been
reported. Fluoride is recognized as being extremely toxic
to fish, wildlife, livestock, and humans. It would
thorugb a POTW without being treated or removed. Therefore,
pretreatment for control of fluoride'is indicated.
209
-------
Page Intentionally Blank
-------
SECTION VIII
COST, ENERGY, AND IMPLEMENTATION
INTRODUCTION
Capital and annual costs for waste water-pretreatment
processes prior to discharge to POTWs are presented for
selected inorganic chemical manufacturing operations. The
costs are expressed in 4th-quarter 1975 dollars.
The following chemicals are considered:
Aluminum chloride (two options) Nickel sulfate
Aluminum sulfate (two options) Nitrogen and oxgen
Calcium carbide . Potassium dichromate
Calcium chloride Potassium iodide
Copper (cuprie) sulfate Silver nitrate
iron (ferric) chloride (two options) sodium bicarbonate
Lead monoxide Sodium fluoride
The costs, cost factors, and costing methodology used to
derive the capital and annual costs are documented following
consideration of the control costs for each chemical
manufacturing subcategory. For the aluminum chlorider
aluminum sulfate, and iron (ferric) chloride subcategories,
additional costs are presented which reflect options avail-
able to reduce the costs of pretreatment. Clearly, use of
these alternative pretreatment technologies will result in
less reduction of pollutants than the primary pretreatment
technologies.
The types of costs shown for each model plant are:
(a) capital costs
(b) annual costs
(c) cost per metric ton of product
The capital and annual costs are total costs. The actual
additional costs a plant would incur in implementing the
described treatment processes depend on current treatment
practices.
The price per metric ton of product and the percentage that
the treatment cost is of the product (selling) price area
also shown. The latter value provides an initial estimate
of the potential economic impact of implementing the
treatment system on the manufacturing operation.
211
-------
The plants are assumed to operate 24 hours per day, 350 days
per year, except where noted otherwise.
Pretreatment costs for chemical manufacturing operations are
based on estimates of daily waste water flows,
concentrations of chemicals in the waste water (as described
in Section vii) , and annual production. Manufacturing
plants are assumed to be single-product plants,
The pretreatment processes for which costs are developed do
not necessarily represent optimum systems, with respect
either to removal or reduction of hazardous chemicals or to
economic efficiency. Bather, the selected pretreatment
processes are representative of the types of systems and
activities which may be required.
Industry costs are based on model-plant characteristics and
treatment proccesses specified for each manufacturing
operation. Treatment costs for a specific manufacturing
operation are primarily a function of the magnitude of the
waste water flow. Available data indicate that flows can
vary significantly among plants manufacturing the same
product. To the extent possible, extrapolation of industry
costs from model -plant costs should be based on flow, rather
than on production capacity.
CONTROL COSTS FOB ALUMINUM CHLORIDE SUBCATEGORY (TABLES 30 6
The treatment processes proposed are:
Metal precipitation/neutralization
Settling
Filtration
Discharge to POTW/sanitary landfill
Caustic soda (sodium hydroxide) is added to the waste stream
at the rate of 2.16 g/1 (18 lb/1000 gal) of waste water and
forms 1.4 g (dry weight) of solids per liter (12 lb/1000
gal) of waste water. Settling tanks sized for 24-hour
retention are provided, yielding an underflow containing 3%
solids. The underflow is pumped through a plate-and- frame
filter. The resultant sludge contains about 101 solids and
has a calculated specific gravity of 1.06. The sludge is
benign and can be disposed of in a sanitary landfill. The
treatment cost is relatively large compared to the product
price, amounting to about 3.5% of the latter.
Alternative treatment processes include metal
precipitation/neutralization and discharge to POTW. Caustic
soda (sodium hydroxide) is added to the waste stream at the
212
-------
TABLE 30. MODEL-PLANT CONTROL COSTS FOR ALUMINUM CHLORIDE INDUSTRY
a. Proposed Pretreatment
PROCESS: Metal ..Precipitation. Neutralization, Settling and Filtration,
Discharge to POTtf, and Sanitary Landfill
PLANT ANNUAL CAPACITY IN METRIC TONS*:
PLANT DAILY WASTEWATER FLOW IN LITERS*:
CAPITAL COST ($)
FACILITIES.
Wastewater sump/sludge pit
EQUIPMENT.
_Met_al-^recipitation/neutrali-
zation system
Settling tank
Filter
9,000
14.300
20,000
Pumps
900
Piping
900
Installation
CONTINGENCY AND CONTRACTOR'S FEE
TOTAL CAPITAL INVESTMENT
44,200
1-9.200
115,200
8,70U
10.100
15,000
900
900
34,700
15.100
90.700
ANNUAL COST {$)
AMORTIZATION
OPERATION AND MAINTENANCE (O&M)
OPERATING PERSONNEL
FACILITY REPAIR AND MAINTENANCE
EQUIPMENT REPAIR AND MAINTENANCE
MATERIALS
TAXES AND INSURANCE
SLUDGE DISPOSAL
ELECTRICITY
TOTAL ANNUAL COST
TREATMENT COST/METRIC TON OF PRODUCT**
PRICE/METRIC TON OF PRODUCT**
% TREATMENT COST OF PRODUCT PRICE
18,780
21.000
200
4,470
17.050
4.610
1.500
1/280
68,670
6.54
14,780
12.600
160
5.520
11.550
5.630
860
1,020
47.920
6.85
J98
3.3
3.5
*To convert to short tons, multiply value shown by 1,1,
*To convert to gallons, multiply value shown by 0.264.
"To convert to cost or selling price/short ton of product, multiply value shown by 0.9,
213
-------
TABLE 31. MODEL-PLANT CONTROL COSTS FOR ALUMINUM CHLORIDE INDUSTRY
b. Alternative Pretreatment
PROCESS:
Nei1trgi:i ZPti™).
PLANT ANNUAL CAPACITY IN METRIC TONS*:
PLANT DAILY WASTEWATER FLOW W LITERS*:
, 500
53, 000
fn
PLANT
A
PLANT
8
7,000
35,300
CAPITAL. COST
FACILITIES.
Wastewater sump
5,500
EQUIPMENT
Metal precipitation/neutralization
System
Pump ir___Tj
Piping
9.000
500
900
Installation
9.500
CONTINGENCY AND CONTRACTOR'S FEE
TOTAL CAPITAL INVESTMENT
5,100
4.490
8.700
400
900
9.100
4.700
28.200
ANNUAL COST ($)
AMORTIZATION
OPERATION AND MAINTENANCE (O&M)
OPERATING PERSONNEL
FACILITY REPAIR AND MAINTENANCE
EQUIPMENT REPAIR AND MAINTENANCE
MATERIALS
TAXES AND INSURANCE
SLUDGE DISPOSAL
ELECTRICITY
TOTAL ANNUALCOST
TREATMENT COST/METRIC TON OF PRODUCT*'
PRICE/METRIC TON OF PRODUCT"
% TREATMENT COST OF PRODUCT PRICE
4,970
8,400
170
1,000
17,050
1.220
1.080
53.870
3.23
4,600
4,200
130
960
11,S50
1.130
830
25.200
3.31
198
1.6
1. 7
•To convert to short tons, multiply value shown by 1.1.
*To convert to gallons, multiply value shown by 0.264.
**To convert to cost or selling price/short ton of product, multiply value shown by 0.9.
214
-------
rate of 2.16 g/1 (18 lb/1,000 gal) of waste water. The
treatment cost is about 1.6X of the product"price.
CONTROL COSTS FOR ALUMINUM SPLFATE SOBCATEGORY (TABLES 32 £
331
The treatment processes proposed are;
Metal precipitation/neutralization
Thickening
Filtration
Discharge to PQTW/sanitary landfill
Each liter of waste water is treated with 11.2 g (0.024 Ib)
of hydrated lime, which forms 30 g (0.07 Ib) of solids (dry
weight). The thickeners are sized for 8-howr retention and.
yield an underflow which contains 15% solids. The use of
rotary vacuum filters thickens the sludge to 401 solids.
This sludge has a'specific gravity of 1.3. Approximately 23
cubic meters (6,100 gallons) and 2 cubic meters (530
gallons) are generated by -Plants A and B, respectively. The
treatment costs range from about 2% to IS of the product
price.
Alternative treatment processes include metal
precipitation/neutralization and discharge to POTW. Each
liter (1,6 quarts) of waste water is treated with 11.2 g
(0.24 Ib) of hydrated lime. The treatment costs range from
about 0.5% to 1.9% of the product price.
CONTROL COSTS FOR CALCIUM CARBIDE SUBCATESORY
No pretreatment of waste water appears necessary for plants
which manufacture calcium carbide.
CONTROL COSTS FOR CALCIOM CHLORIDE SOBCATEGORY
No pretreatment of waste water appears necessary for plants
which manufacture calcium chloride.
CONTROL COSTS FOR COPPER (CUPRIC) SULFATE SUBCATSGORY (TABLE
MI
The treatment processes proposed ares
Metal precipitation/neutralization
Settling
Discharge to POTW/chemical landfill
Hydrated lime is added at a rate of 1,2 g per liter (10
lb/1000 gal) of waste water. This results in the formation
215
-------
TABLE 32. MODEL-PLANT CONTROL COSTS FOR ALUMINUM SULFATE INDUSTRY
a. Proposed Pretreatment
PROCESS: _Metal Precipitation,^Neutralization, Thickening. Discharge to POTff
"and Sanitary Landfill
PLANT
A
PLANT
B
PLANT ANNUAL CAPACITY IN METRIC TONS*:
PLANT DAILY WASTEWATER FLOW IN LITERS*:
64.000
400,000
40.000
54.000
CAPITAL COST (S)
FACILITIES.
Wastewater sump/sludge pit
EQUIPMENT,
jfetal precipitation/neutralization
system
52,800
15.000
6.500
8.500
Thickener
Filter
Pumps
JI6.000
65.000
1.500
Piping
6.000
Installation
117.500
CONTINGENCY AND CONTRACTOR'S FiE
TOTAL CAPITAL INVESTMENT
54.800
328.600
12.500
26.500
900
900
48,400
20.800
124.800
ANNUAL COST <$|
AMORTIZATION
OPERATION AND MAINTENANCE IO&MJ
OPERATING PERSONNEL
FACILITY REPAIR AND MAINTENANCE
EQUIPMENT REPAIR AND MAINTENANCE
MATERIALS
TAXES AND INSURANCE
SLUDGE DISPOSAL
ELECTRICITY
TOTAL ANNUAL COST
TREATMENT COST/METRIC TON OF PRODUCT**
PRICE/METRIC TON OF PRODUCT*'
% TREATMENT COST OF PRODUCT PRICE
53.560
33,600
980
12.050
84.700
15.140
52.500
20. MO
25_, 200
190
4.880
7.200
4.990
4.460
11.870
262.400
4.10
2.550
69.810
1.74
_98_
4.2
1.8
*To convert to short tons, multiply value shown by 1.1.
'To convert to gallons, multiply value shown by 0.264.
**To convert to cost or selling price/short ton of product, multiply value shown by 0.9.
216
-------
TABLE 33. MODEL-PLANT CONTROL COSTS FOR ALUMINUM SULFATE INDUSTRY
b. Alternative Pretreatment
PROCESS: Metal' Precipitation, Neutralization, Discharge to POTW - -
PLANT ANNUAL CAPACITY IN METRIC TONS":
PLANT DAILY WASTEWATER FLOW IN LITERS*:
CAPITAL COST ($)
FACILITIES.
Wastewater sump
EQUIPMENT.
Metal precipitation/neutralization
System
15,000
Pumps
8,500
1,000
500
Piping
6,000
900
Installation
CONTINGENCY AND CONTRACTOR'S FEE
TOTAL CAPITAL INVESTMENT
16,000
11.800
71.000
9,400
4.700
28^300
ANNUAL COST ($)
AMORTIZATION
OPERATION AND MAINTENANCE (O&M)
OPERATING PERSONNEL
FACILITY REPAIR AND MAINTENANCE
EQUIPMENT REPAIR AND MAINTENANCE
MATERIALS
TAXES AND INSURANCE
SLUDGE DISPOSAL
ELECTRICITY
TOTAL ANNUAL COST
TREATMENT COST/METRIC TON OF PRODUCT**
PRICE/METRIC TON OF PRODUCT**
% TREATMENT COST OF PRODUCT PRICE
11,570
12,600
640
1,900
84,700
2,840
2.810
117,060
1.83
1.9
4,610
4,200
130
970
7,200
1,130
890
19,130
0.48
98
0.5
•To convert to short torts, multiply value shown by 1.1.
^To convert to gallons, multiply value shown by 0.264.
"To convert to cost or selling price/short ton of product, multiply value shown by 0.9.
217
-------
TABLE 34. MODEL-PLANT CONTROL COSTS FOR COPPER (CUPRiC)
SULFATE INDUSTRY
PROCESS: Metal Precipitation, Neutralization. Settling,,, Discharge to POTW,
and Chemical Landfill
PLANT ANNUAL CAPACITY IN METRIC TONS';
PLANT DAILY WASTEWATER FLOW IN LITERS*:
PLANT
A
PLANT
B
21.000
33.000
12.500
19.600
CAPITAL COST ($»
FACILITIES.
Wastewater sump/sludge pit
EQUIPMENT.
_Me t al-p r e c ip i t ation/Neut r al i_—
zationsystem
JSettling
Pumps ___
Piping
Installation
CONTINGENCY AND CONTRACTOR'S FEE
TOTAL CAPITAL INVESTMENT
4,900
8,500
9,700
900
900
19.100
8.8Q.Q...
52.800
4,000
8.200
7,000
900
900
16.100
7.400
44.5QQ
ANNUAL COST S8)
AMORTIZATION
OPERATION AND MAINTENANCE (O&MJ
OPERATING PERSONNEL
FACILITY REPAIR AND MAINTENANCE
EQUIPMENT REPAIR AND MAINTENANCE
MATERIALS
TAXES AND INSURANCE
SLUDGE DISPOSAL
ELECTRICITY
TOTAL ANNUAL COST
TREATMENT COST/METRIC TON OF PRODUCT"
PRICE/METRIC TON OF PRODUCT**
% TREATMENT COST OF PRODUCT PRICE
8.610.,
8.400
150
1.960
760
2JLUL
6.980
640
29.610
1.41
7.250
8.400
120
1.660
450
1.780
4.150
640
24.450
1.96
835
0,2
0.2
*To convert to short tons, multiply value shown by 1.1.
•To convert to gallons, multiply value shown by 0.264.
**To convert to cost or selling priee/ihort ton of product, multiply »a!ut ihown by 0.9.
218
-------
of 2 g of dry solids per liter (17 Ib/lQQQ gal) of waste
water. The overflow from the settling tanks, sized for 24-
hour retention, is discharged to a PQTW. The underflow is
sent to a secure landfill* The treatment costs represent
0.2% of the product price.
CONTROL COSTS FOR IRQ! (FERMIC) CHLORIDE SUBCATE60RY (TABLES
35 B 36)
The treatment processes proposed are:
Metal precipitation/neutralization
Settling
Centrifuging
Discharge to POTW/recycle
The addition of 9 g of hydrated lime per liter (75 lb/1000
gal) of waste water forms 10 g of solids {dry weight) per
liter (83 lb/1000 gal) of waste water. The waste stream is
directed to a settling tank, sized for 24-hour retention.
The underflow from the settling tank (10% solids) is
centrifuged. The resultant sludge is about 30% solids and
is recycled. The sludge has an estimated specific gravity
of 1.28. Approximately 1.3 cubic meters (310 gallons) and
0.23 cubic meter (61 gallons) of sliidge, respectively, are
recycled daily from Plants A and B. The cost of the
proposed treatment is significant, amounting to 2 to 6% of
product price. ' ,
Alternative treatment processes include metal
precipitation/neutralization and discharge to POTW.
Treatment consists of the addition of 9 g of hydrated lime
per liter (75 lb/1,000 gal) of waste water. The cost of the
proposed treatment amounts to 1.3X to 2,61 of product price.
CONTROL COSTS FOR LEAD MONOXIDE (TABLE 37)
The treatment processes proposed are:
Metal precipitation/neutralization
Settling
Discharge to POTW/recycle to lead smelters
The waste stream is treated with 0.35 g of hydrated lime per
liter (2.9 lb/1000 gal) of waste water. This forms about
2.5 g of solids (dry weight) per liter (21 lb/1000 gal) of
waste water. The settling tanks are sized for 1-hour
retention. The sludge, after settling, is estimated to be
about 50% solids with a specific gravity of 1.6. The daily
amount of sludge recycled from Plant A is l.ii cubic meters
(370 gallons): from Plant B» 1.1 cubic meters (290 gallons).
219
-------
TABLE 35. MODEL-PLANT CONTROL COSTS FOR IRON (FERRIC)
CHLORIDE INDUSTRY
a. Proposed Pretreatment
PROCESS: MetalPrecipitation, Neutralization, Settling, Discharge to POTWj
and Chemical Landfill
PLANT
A
PLANT
B
PLANT ANNUAL CAPACITY IN METRIC TONS':
PLANT DAILY WASTEWATER FLOW IN LITERS*:
19,600
51,100
S.QOO
13.000
CAPITAL COST ($1
FACILITIES .
Wastewater sump/sludge pit
7,300
EQUIPMENT.
Metal-precipitation/neutrali-
2ation system"
Settling
Centrifuge
4.800
8.800
8.200
8.200
20,000
3.400
Pumps
900
Piping
900
Instillation
37.900
CONTINGENCY AND CONTRACTOR'S FEE
TOTAL CAPITAL INVESTMENT
100,800
20,000
900
900
32.500
14,100
84,800
ANNUAL COST f$)
AMORTIZATION
OPERATION AND MAINTENANCE (O&MI
OPERATING PERSONNEL
FACILITY REPAIR AND MAINTENANCE
EQUIPMENT REPAIR AND MAINTENANCE
MATERIALS
TAXES AND INSURANCE
SLUDGE DISPOSAL
ELECTRICITY
TOTAL ANNUAL COST
TREATMENT COST/METRIC TON OF PRODUCT*
PRICE/METRIC TON OF PRODUCT"
% TREATMENT COST OF PRODUCT PRICE
16,450
8,400
220
3.840
8.860
4.050
1.320
43.100
2.20
15.820
4.2QQ
140
3.300
2.250
5.390
740
27.840
5.56
-iOO_
2.0
5.6.
*To convert to short tons, multiply value shown by 1,1.
*To convert to gallons, multiply value shown by 0,264.
•*To convert to cost or selling price/short ton of product, multiply value shown by 0.9.
220
-------
TABLE 3i, MODEL-PLANT CONTROL COSTS FOR IRON (FERRIC) CHLORIDE INDUSTRY
b. Alternative Pretreatmern
PROCESS- Metal Precipitation/Neutralization, Discharge to POTW
PLANT ANNUAL CAPACITY IN METRIC TONS*:
PLANT DAILY WASTEWATER FLOW IN LITERS*;
CAPITAL COST ($|
FACILITIES
Wastewater siimp
EQUIPMENT,
Meta1 precip itat ion/neutra1i zation
System
8.800
8.200
Pump
500
400
Piping
900
900
Installation
CONTINGENCY AND CONTRACTOR'S FEE
TOTAL CAPITAL INVESTMENT
9.500
8,600
5.000
29,900
4.JLQ.CL
24.500
ANNUAL COST It)
AMORTIZATION
OPERATION AND MAINTENANCE (OUtM)
OPERATING PERSONNEL
FACILITY REPAIR AND MAINTENANCE
EQUIPMENT REPAIR AND MAINTENANCE
MATERIALS
TAXES AND INSURANCE
SLUDGE DISPOSAL
ELECTRICITY
TOTAL ANNUAL COST
TREATMENT COST/METRIC TON OF PRODUCT**
PRICE/METRIC TON OF PRODUCT**
% TREATMENT COST OF PRODUCT PRICE
4.870
3.990
8.400
4.200
160
70
980
910
8,860
2,250
1,200
980
830
25.300
570
12.970
1.29
2.59
100
1.3
2.6
"To convert to short tons, multiply value shown by 1.1.
tTo convert to gallons, multiply value shown by 0.264.
**To convert to cost or selling price/short ton of product, multiply value shown by 0.9.
221
-------
TABLE 37. MODEL-PLANT CONTROL COSTS FOR LEAD MONOXIDE INDUSTRY
PROCESS: Metal Precipitation, Neutralization, Settling. Discharge to POTW.
and Sludge Recycle
PLANT ANNUAL CAPACITY IN METRIC TONS*:
PLANT DAILY WASTEWATER FLOW IN LITERS*;
CAPITAL COST (S)
FACILITIES
Wastewater sump/sludge pit:
EQUIPMENT
Metal-precipitation/neutrali-
zation system
Settling
Pumps
Piping
Installation
CONTINGENCY AND CONTRACTOR'S FEE
TOTAL CAPITAL INVESTMENT
16.000
14.0fJ,i
17.600
i4.
1.200
i.onn
90Q.
54.800
18,600
111.800
snn
29.500
15,ROfL
95.500
ANNUAL COST (S)
AMORTIZATION
OPERATION AND MAINTENANCE (O&M)
OPERATING PERSONNEL
FACILITY REPAIR AND MAINTENANCE
EQUIPMENT REPAIR AND MAINTENANCE
MATERIALS
TAXES AND INSURANCE
SLUDGE DISPOSAL
ELECTRICITY
TOTAL ANNUAL COST
TREATMENT COST/METRIC TON OF PRODUCT*'
PRICE/METRIC TON OF PRODUCT**
% TREATMENT COST OF PRODUCT PRICE
18.220
12 ,600
680
15.570
8.400
600
2.990
2.950
2.350
4.470
3.820
3,060
45.510
2 .SSO
36.2SO
2.28
2.28
_53D_
O.A
0.4
*To convert to short tons, multiply value shown by 1.1.
^To convert to gallons, multiply value shown by 0.264.
**To convert to cost or selling price/short ton of product, multiply value shown by 0.9.
222
-------
The cost of treatment represents only 0.41 of the product
price*
CONTROL COSTS FOR NICKEL SOLFATS SUBCATEGORY {TABLE 38)
The treatment processes proposed are:
Metal precipitation/neutralization
Settling
Discharge to POTW/chemical landfill
Plant A operates 8 hours per day, 42 days per year; Plant Br
16 hours per day, 250 days per year. The amount of waste
water generated is very small. It is directed to a
mixing/settling tank, sized for 24-hour retention, where
hydrated lime in the amount of 0.5 g per liter (4 lb/1000
gal) of waste water is added manually. Gravity flow is
assumed.
Solids formed in the process have an estimated dry weight of
0.7 g per liter (5.8 lb/1000 gal) of waste water. The
underflow from the settling tanks consists of about 5%
solids and has a specific gravity of about 1.1. The amount
of sludge collected daily from Plant A is 0.072 cubic meter
(19 gallons); from Plant B, 15 cubic meters (3,960 gallons).
The treatment cost represents 0.2 to 1.3% of the product
price*
An alternative treatment process includes, in addition to
the above treatments, directing the overflow from the
settling tanks through a sand filter prior to discharge to a
POTW. The incremental capital and annual costs of this
process are:
Plant A Plant B
Capital $11,900 $11,900
Annual Cost $4,680 $3,180
Sand filtration would be required only for about 2 hours per
day in Plant A, and for 30 minutes per day in Plant B. The
treatment cost per metric ton (per short ton) of product
would be increased by $2.06 ($1.87) in Plant A and by $41.84
($37.95) in Plant B. The very large increase in Plant B is
due to the limited annual production. The percent of
treatment cost of product price with sand filtration is 0.3%
for Plant A and 3.8% for Plant B.
CONTROL COSTS FOR NITROGEN AND OXYGEN SOBCATEGORY (TABLE 39)
The treatment processes proposed are:
223
-------
TABLE 38. MODEL-PLANT CONTROL COSTS FOR NICKEL SULFATE INDUSTRY
PROCESS: MetalPrecipitation. Neutralization, Settling, Discharge to POTW,
and Chemical Landfill
PLANT
A
PLANT
B
PLANT ANNUAL CAPACITY IN METRIC TONS':
PLANT DAILY WASTEWATER FLOW IN LITERS*:
2,270
5,680
76
1,135
CAPITAL COST (SJ
FACILITIES
Sludge pit
300
EQUIPMENT
Mixing/settling tanh
4.500
Pump
500
Pi-ping
400
Installation
5,000
CONTINGENCY AND CONTRACTOR'S FEE
TOTAL CAPITAL INVESTMENT
2.100
12.800
300
1,400
500
400
1.900
900
5.400
ANNUAL COST ($)
AMORTIZATION
OPERATION AND MAINTENANCE {O&M)
OPERATING PERSONNEL
FACILITY REPAIR AND MAINTENANCE
EQUIPMENT REPAIR AND MAINTENANCE
MATERIALS
TAXES AND INSU RANGE
SLUDGE DISPOSAL
ELECTRICITY
TOTAL ANNUAL COST
TREATMENT COST/METRIC TON OF PRODUCT*'
PRICE/METRIC TON OF PRODUCT"
% TREATMENT COST OF PRODUCT PRICE
2,090
5,000
10
520
60
510
910
270
7,570
3.25
880
250
10
210
10
220
30
10
1.620
21.32
1,672
0.2
1.3
*To convert to short tons, multiply value shown by 1.1.
^ To convert to gallons, multiply value shown by 0.264.
**To convert to cost or selling price/short ton of product, multiply value shown by 0.9.
224
-------
TABLE 39. MODEL-PLANT CONTROL COSTS FOR NITROGEN AND
OXYGEN INDUSTRY
PROCESS: Coalescing, Discharge to POTW, and Chemical Landfill
PLANT PLA
A E
NT PLANT
C
PLANT ANNUAL CAPACITY IN METRIC TONS': 250,000 165,000 36,000
PLANT DAILY WASTEWATER FLOW IN LITERS1": 26,500 17,500 3,800
CAPITAL COST ($)
FACILITIES
Wastewater sump 3,800 ' 2,700 1,000
EQUIPMENT
Coalescer 1 ,400 ;
Pumps 500
Piping 400
..400 1 r400
50C 500
400 400
Installation 1,900 1,900 1.900
CONTINGENCY AND CONTRACTOR'S FEE 1,600 1,400 1.000
TnjAI CAPITA) INVESTMENT 9,600 8.300 6.200
ANNUAL COST ($)
AMORTIZATION 1.560 1.350 1.010
OPERATION AND MAINTENANCE (O&M)
OPERATING PERSONNEL 2.50Q 3
FACILITY REPAIR AND MAINTENANCE 11Q ,
EQUIPMENT REPAIR AND MAINTENANCE A 21(1 -
MATERIALS ~"~ .
TAXES AND INSURANCE 380
SLUDGE DISPOSAL _ 500
ELECTRICITY 60
,870 l,2Sn
so in
?in ?io
— —
330 80
330 70
60 60
TOTAL ANNIIAI COST 5,320 4,230 2,710
TREATMENT COST/METRIC TON OF PRODUCT** 0.02
0.03 0.08
PRICE/METRIC TON OF PRODUCT** 40 tt
n rm
0.08 0.2
*To convert to short tons, multiply value shown by 1.1.
'To convert to gallons, multiply value shown by 0.264.
* *To convert to cost or selling price/short ton of product, multiply value shown by 0.9.
* 'Nitrogen only.
225
-------
Coalescer
Discharge to POTW/chemieal landfill
Flow through the coalescer is estimated to reduce the
pollutants by about 971. The daily amount, of .oil and grease
.recovered is very small, only about 29 1 (7,6 gal) for the
largest plant considered. The treatment cost is not
significant.
An alternative treatment process is considered for Plant B.
Water from the waste water sump flows into an adjacent sump
(sized for 12-hour retention)» where the oil is skimmed from
the surface. This process is estimated to remove 901 of the
oil.
Costs for Model-Plant B are;
Capital Cost $6,200
Annual Cost $3,020
Cost/Metric (Short) Ton of Product $0.02 ($0.018)
X Treatment Cost of Product Price 0.05
COJTROL COSTS FOR POTASSIUM BICHROMATE SOBCATEGORY (TABLE
121
The treatment processes proposed are:
Chemical chromate removal
Neutralization
Thickening
Filtration
Discharge to POTW/chemical landfill
Chromate removal and neutralization are achieved by the
addition of 0.25 g (0.0006 Ib) of sulfur dioxide, 0.25 g
(0.0006 Ib) of sulfuric acid, and 0.3 g (0.0007 Ib) of
hydrated lime to each liter (0.26 gal) of waste water.
Resulting solids amount to 0,96 g (dry weight) per liter
(0.008 Ib/gallon) of waste water.
The thickeners employed are sized for 8-hour retention and
form an underflow containing 51 solids. The underflow is
pumped through a precoated, rotary vacuum filter.
Approximately 1 leg (2.2 Ib) of precoat (diatomaceous earth)
is consumed for each $ kg (8.82 Ib) of filter cake. The
latter contains 201 solids and has a specific gravity of
1.1.
226
-------
TABLE 40. MODEL-PLANT CONTROL COSTS FOR POTASSIUM
DICHROMATE INDUSTRY
PROCESS- Chromate Removal, Neutralization, Thickening, Filtration,
Di s charge"to POTW, and Chemlcal Landfi11
PLANT
A
PLANT
B
PLANT ANNUAL CAPACITY IN METRIC TONS':
PLANT DAILY WASTEWATER FLOW IN LITERS*:
3,600
164,000
CAPITAL COST ($)
FACILITIES.
Wastewater sump/sludge pit
EQUIPMINT,
Chemical chromate -removal system
Metal -precipitation/neutrali-
zation system _
Thickener _
Filter _
Pumps _ ; _ : _ _____
InstallatiQB
CONTINGENCY AND CONTRACTOR'S FEE
TOTAL CAPITAL INVESTMENT
15,000
19.800
11,000
25,000
22,000
1.700
2,500
79.500
54.900
209,400
ANNUAL COST ($)
AMORTIZATION
OPERATION AND MAINTENANCE (O&M)
OPERATING PERSONNEL
FACILITY REPAIR AND MAINTENANCE
EQUIPMENT REPAIR AND MAINTENANCE
MATERIALS
TAXES AND INSURANCE
SLUDGE DISPOSAL
ELECTRICITY
TOTAL ANNUAL COST
TREATMENT COST/METRIC TON OF PRODUCT**
PRICE/METRIC TON OF PRODUCT**
% TREATMENT COST OF PRODUCT PRICE
54.150
16.800
590
8.040
8 150
8.580
12.530
5.910
92.510
25.71
1.254
2,1
*To convert to short tons, multiply value shown by 1.1.
*To convert to gallons, multiply value shown by 0.264.
**To convert to cost or selling price/short ton of product, multiply value shown by 0.9.
227
-------
Daily, Plant A generates about 1,200 1 (317 gal) of sludge,
and plant B, 700 1 (185 gal) of sludge, which are disposed
in a chemical landfill. The treatment cost amounts to
approximately 2% of the product price.
CONTROL COSTS FOB POTASSIUM IODIDE SUBCATEGORY
A preliminary analysis indicates that no pretreatment of
small waste water flows appears necessary for plants which
manufacture potassium iodide,
CONTROL COSTS FOR SILVER NITRATE SPBCATSSORY (TABLE 41)
The treatment processes proposed are:
Metal precipitation/neutralization
Flocculation
Filtration
Discharge to POTW/recycle
Material additions to the waste stream consist of 0.2 g
(0.0004 Ib) of hydrated lime and 2 mg of polyelectrolyte per
liter of waste water. This material is added manually to
the waste water in a mixing tank. In addition, about 1 kg
(2.2 Ib) of Filter Aid (diatomaceous earth) is used each
week.
The waste water is recirculated through a plate-and-frame
precoated filter until the filtrate appears clear. The
amounts of solids produced are very small, amounting to
about 1.1 liters (0.29 gallon} per day in Plant A and 0.1
liters (0.03 gallon) in Plant B.
The treatment cost is not significant when compared to the
value of the product manufactured.
CONTROL COSTS FOR SODIUM BICARBONATE SUBCATEGORY
No pretreatment of waste water appears necessary for plants
which manufacture sodium bicarbonate,
CONTROL COST FOR SQDIflM FLOORIDE SOBCATEGORY (TABLE 42
The treatment processes proposed are:
Metal precipitation/neutralization
Flocculation
Settling
Filtration
Discharge to POTW/chemical landfill
228
-------
TABLE 41. MODEL-PLANT CONTROL COSTS FOR SILVER NITRATE INDUSTRY
PROCESS: Metal Precipitation, Neutralizaticm,_Flocculation, Filtration,
Discharge to POTW, and Recycle
PLANT ANNUAL CAPACITY IN METRIC TONS*:
PLANT DAILY WASTEWATER FLOW IN LITERS*:
CAPITAL COST ($}
FACILITIES.
Wastewater sump
EQUIPMENT
Mixing tank
1,300
Recycle tank
1,100
700
Filter
Pumps
12.000
900
8,000
900
Piping
500
300
Installation.
15.300
CONTINGENCY AND CONTRACTOR'S FEE
TOTAL CAPITAL INVESTMENT
6.600
39,800
10.400
4,300
25,800
ANNUAL COST <$)
AMORTIZATION
OPERATION AND MAINTENANCE (O&M)
OPERATING PERSONNEL
FACILITY REPAIR AND MAINTENANCE
EQUIPMENT REPAIR AND MAINTENANCE
MATERIALS
TAXES AND INSURANCE
SLUDGE DISPOSAL
ELECTRICITY
TOTAL ANNUAL COST
TREATMENT COST/METRIC TON OF PRODUCT**
PRICE/METRIC TON OF PRODUCT**
% TREATMENT COST OF PRODUCT PRICE
6^490
12.600
60
4,210
4.200
10
1.560 1.060
20 10
1-590
260
190
10.710
7.06
30.60
90.000
0.007
0.03
•To convert to short tons, multiply value shown by 1,1.
'''To convert to gallons, multiply value shown by 0.264.
••To convert to cost or selling price/short ton of product, multiply value shown by 0,9.
229
-------
TABLE 42. MODEL-PLANT CONTROL COSTS FOR SODIUM FLUORIDE INDUSTRY
PROCESS: Metal Precipitation, Neutralization, Flocculation, Settling.
Filtration, Discharge to POTW, and Chemical Landfill
PLANT
A
PLANT
8
PLANT ANNUAL CAPACITY IN METRIC TONS*;
PLANT DAILY WASTEWATER FLOW IN LITERS*:
5.200
18.000
CAPITAL COST ($)
FACILITIES
Wastewater sump/sludge pit
4.300
EQUIPMENT
Metal precipitation/neutralization
System
8.200
Flocculation system
1.600
Settling tank
6.700
Filter
22.000
Pump
son
Piping
500
Installation
39.000
CONTINGENCY AND CONTRACTOR'S FEE
TOTAL CAPITAL INVESTMENT
16.600
99.400
ANNUAL COST ($)
AMORTIZATION
OPERATION AND MAINTENANCE (O&M)
OPERATING PERSONNEL
FACILITY REPAIR AND MAINTENANCE
EQUIPMENT REPAIR AND MAINTENANCE
MATERIALS
TAXES AND INSURANCE
SLUDGE DISPOSAL
ELECTRICITY
TOTAL ANNUAL COST
TREATMENT COST/METRIC TON OF PRODUCT"*
PRICE/METRIC TON OF PRODUCT**
% TREATMENT COST OF PRODUCT PRICE
16,200
25,200
150
3,930
15.720
3.980
11.450
1.810
78.420
24.51
640
5.R
•To convert to short tons, multiply value shown by 1.1.
^To convert to gallons, multiply value shown by 0.264.
»»To convert to cost or selling price/short ton of product, multiply value shown by 0.9.
230
-------
Materials added to the waste water consist of calcium
chloride, at a concentration of 26.4 g/1 (220 lb/1,000 gal},
and polyelectrolyte at a concentration of 10 mg/1 (0.83
lb/1,000 gal). The resulting solids amount to 18 g (dry
weight) per liter (150 lb/1,000 gal) of waste water.
The settling tank is si2ed for 24-hour retention. The
underflow from the settling tank consists of 151 solids.
This sludge is thickened in a rotary vacuum filter, which
produces filter cake containing 10% solids. The estimated
specific gravity of the filter cake is 1.24. The daily
amount of waste sent to the landfill is about 650 liters
(172 gallons).
The treatment costs represent 3.8% of product cost.
DEVELOPMENT OF COST DATA BASE
The costs, cost factors, and costing methodology used to
derive the capital and annual costs are documented in this
subsection.
Most of the equipment costs are based on vendor quotations.
The names of vendors are deleted to avoid any implications
of product endorsement. vendor identification will be
provided, oh request, to EPA and others authorized by EPA.
The following categorization is used for presenting the
costs:
Capital Cost
Facilities
Equipment
Installation
Contingency and Contractor*s Fee
Annual Cost
Amortization
Operation and Maintenance
Operating Personnel
Facility Repair and Maintenance
Equipment Repair and Maintenance
Materials
Taxes and Insurance
Sludge Disposal
Energy
231
-------
Capital cost, of Facilities
Concrete pits sized to contain a 2*-hour flow of waste water
are included with most treatment processes. In addition,
concrete sludge-holding pits are provided, generally
designed to hold a 7-day supply of sludge.
The pits are constructed of 20-centimeter (8-inch)
reinforced base slabs and <*Q-centimeter (16-inchJ walls. A
general cost-estimating relationship was developed from
Reference 18, resulting in a base slab cost of $20/square
meter ($2/sguare foot) and a wall cost of $300/cubic meter
(f8/cubic foot) of concrete in place. The costs include
setup and layout, excavation, concrete, backfill, and
cleanup.
For example, the cost of a 6-cubic-meter (212-square-foot)
pit, measuring 3mx2mxlm (9,8 ft x 6,6 ft x 3.3 ft) is
computed as follows:
(3 x 2 x $20) + (2 x 3 x 1 x 0, «t x ,$300) * (2 x 2 x 1 x 0.4
x $300) = $1,320
Capital cost of Equipment
General. Certain types of equipment, such as metal-
precipitation/neutralization systems, thickeners, tanks, and
pumps, are widely used in the described treatment processes.
Parametric cost curves are developed for such items to
facilitate the cost computations.
Chemical Chrornate-Removal/Metal-^ecipitation/Neutralization
Systems. System costs as a function of waste water flow,
expressed in liters (= 0.264 gallon) per minute, are shown
in Figure 58. Costs are based on vendor quotations,
The costs represent packaged, factory-assembled units. The
major system components are generally skid-mounted;
interconnected; and include associated pumps, meters, and
instrumentation.
Electrochemical chromate removal is applicable primarily to
.coolingtower washdown waste water--i.e., relatively large•
flows which contain small amounts of chromates. chemical
chromate removal is selected as the system of choice where
applicable in this study.
FlQcculant Feed Systems. The flocculant feed system
consists of a tank, a feed pump (mounted under the tank),
interconnecting piping with reliefreturn system, and
232
-------
Figure §8. TREATMENT-SYSTEM COSTS
300
100
70
50
fi30
ro
8 io
7
, S
4—
ELECTROCHEMICAL
CHROMATE
REMOVAL
CHEMICAL
CHROMATE
REMOVAL
(MOTOR
METAL
HORSEPOWER
,„... _ REQUIRED)
PRECIPITATION/NEUTRALIZATION
_|
!
_+.
+
—i—
i _*
-+-
..4
i
-«*».|™,
:.±
,—T.
.44411=
•H-++H—
--fi-t-ffi—
I ! ! ' '•
*
7TT"
--,}, mm_^,__4-(al ^n^ntpH>m»f»nmmm^
I \ \ll
.44141
u
10
30 60 100 300
FLOW {Ifmm}
500 700 1000
3000
l/min x 0.2642 = gpm
hp x 0.7457 = kW
233
-------
stainless steel agitator. System design and costs were
obtained from an equipment manufacturer. Costs are:
Tank Size Cost
190-1 (50-gal) $1,600
570-1 (150-gal) 2,000
1,900-1 (500-gal) 3,500
Equipment is selected for employment at plant operations
based on treatment flow requirements.
Holding/Settling Tanks. Costs, based on vendor quotations,
are shown in Figure 59, as a function of capacity. The
tanks are of steel construction.
Thickeners. Costs for rake-type thickeners as a function of
volume are shown in Figure 60. The costs represent vendor
quotations. The thickeners are relatively small and are
powered by electric motors ranging from about 0.4 to 6.5 kW
(0.5 to 2 hp) in size. To illustrate the application of
Figure 60, an operation with a daily flow of 100 cubic
meters (26,000 gallons) of waste water requiring a
thickener, sized for 6-hour retention, would require a 25-
cubic-meter (6,600-gallon) thickener and would incur a cost
of $17,500.
Sludge-Dewatering Equipment. The use of such equipment may
be dictated in large part by the economics of chemical
landfill costs. This is illustrated in Figure 61, which
demonstrates potential cost savings achievable by reducing
the volume of sludge to be disposed. For example, an
operation which generates 10 cubic meters (2,641 gallons) of
sludge per day and is able to reduce this volume by 30X
through settling/filtration reduces its sludge disposal cost
of $150. Specific sludge-dewatering equipment costs, based
on vendor quotations, are presented.
Rotary Vacuum Filters. Characteristics and costs of rotary
vacuum filters are shown in Table 43. Filter selection for
specific operations is based on solid content in the waste
stream which is expected to be separated by filtering.
Centrifuges. Costs, as a function of weight of sludge
generated per day, are shown in Figure 62. Power
requirements for the size of centrifuges shown range from 25
to 18.6 kW (10 to 25 hp) . The curve given in Figure 62
should not be extended beyond the lowest point shown, since
this point represents the smallest applicable centrifuge
manufactured. Costs are based on equipment-manufacturer
quotations.
234
-------
Figure 59. SETTLING/HOLDING-TANK COSTS
t-trr
riTt
+-+-4H-
300
VOLUME (m3t
x 264.172 - gal
235
-------
Figure 60. THICKENER COSTS
70
50
K)
o 30
5
CO
O
u
10
__. ,
10
30 50 70 100
VOLUMI (m3)
300 500
m3 x 264.172 = gal
236
-------
Figure 61. DAILY SAVINGS ACHIEVED BY VOLUME REDUCTION OF SLUDGE
BASED ON DISPOSAL COST OF $50/m3 ($38/yd3)
1000
700
500
300
s100
r*.
? 70
S 5**
10
7
5
1
0.1 0.3 0.5 0.7 1.0 3 57 10
SLUDGE GENERATED/DAY (m3)
30 50 70 100
x 264.172 =
237
-------
TABLE 43. ROTARY VACUUM-FILTER COSTS
FILTER
DESIGNATION
3x1
3x2
3x3
3x4
3x5
FILTER AREA
m2 ft2
0.86 9.4
1.66 18.8
2.59 28.2
3.46 37.6
4.32 47.0
COST
$22,000
25,000
26,500
28,000
30,000
CAPACITY FOR
DRY SOLIDS/HOUR
kf
31.8
63.6
95.5
127.3
159.1
Ib
70
140
210
280
350
ENERGY
REQUIREMENTS
hp
10
12
14
16
18
kW
8
9
10
12
13
SOURCE: EQUIPMENT MANUFACTURER
238
-------
Figure 62. CENTRIFUGE COSTS
1000
100
en
v>
-f 4—4—+—j-44- 4-
; :
i- r—4—+-4-4-f
10
100
1000
.FLOW (metric tons of sludge/day)
metric tons x 1.1 * short tons
239
-------
Sand Filters. Sand-filter costs are shown as a function of
flow rate in Figure 63. The flow rate of the type of sand
filters from which the costs are derived is 205 to 250
I/square meter/min (5 to 6 gal/square ft/min).
Piate-and-Frame Filters. Cost quotations were obtained from
vendors for filters applicable to specific, postulated
treatment processes. They are:
122-cm (48-inch) 30 plates $20,000
122-cm (48-inch) 20 plates 15,000
61-cm (21-inch) 24 plates 12,000
61-cm (2**-inch) .4 plates 8,000
Mixing Tanks. Mixing-tank costs are shown in Figure 64.
The tanks are of steel construction and include agitators
and motors. Costs are based on a vendor quotation.
Coalescers. Vendor cost quotations obtained for water
coalescers are;
19 to 38 1 (5 to 10 gal)/min $1,400
42 to 87 1 (11 to 23 gal)/min 1,600
76 to 152 1 (20 to 40 gal)/min 1,800
Pumps. Pump costs, including motors, are shown in Figure 65
as a function of capacity, expressed in liters (=0.264
gallon)/minute. The types and sizes of pumps required for a
particular activity can vary widely, depending on the
characteristics of the material being pumped and the height
and distance the material must be transported. The pump
costs in Figure 65 are representative of centrifugal pumps
capable of pumping to a head of about 6 m (20 ft) .
Pipes. Installed costs of several types of pipes are shown
in Table 44, The basic costs are increased by 20% to
account for ancillary items, such as connectors, tees, and
valves. PVC piping is generally employed.
Capital Cost of Installation
Many factors can impact on the cost of installing equipment
modules. These include wage rates, whether the job is
performed by outside contractors or regular employees, and
site-dependent conditions (e.g., availability of sufficient
electrical service).
In this study, installation cost is computed as 100% of the
cost of equipment which is installed, less piping. Note
that the costs of major treatment-system components, such as
metal-precipitation/neutralization equipment, are based on
240
-------
Figure 63. SA.ND-FCLTER COSTS
70 100
FLOW (l/min)
500 700 1000
l/min x 0.2642 = gpm
241
-------
Figure 64. MIXING-TANK COSTS
10
7
5
2 1.0
H
O 0.7
0.5
0.3
0.1
"t-t"J"i-tTl
0.1
0.3
0.5 0.7 1.0
VOLUME (m3)
10
m3 x 214.172 = gal
ftp x 0.7457 - kW
242
-------
Figure 65. PUMP COSTS
IW,UUU
7000
5000
3000
I
~ 1000
1
W 700
500
300
h _l . i j . j. j i jLi_j i . r A— L- i"
,„ M ;
.-«™--™— „"».
. '
~
•
—
— —»
..„,**
t n
.^.^^-^-+—__*^__-
f t
- — -j — -f — j
i i
_ r-
r ~j"~ ~
t
¥
— .
—
...c
,: .-
£/
—
i-j '• _
„ .11. ,
i
., ,._.' .. _,«„„..
4-i—
D = 6m (3.6 ft)
,* -j— I.—..*,-,.....—,, J
i
f
t
>S 31i PUMP
(1/4) <1
fltOTOKHORSEPO
-~\~r-t-
' * f 1
^,*^_J- L- __ _ ___
.4.
ASTIR
W
.11/4
HOT
i
i
— L
i
i
t
t
I
T
T
1
i • .
r r
ON PUMP .
L . 11
3RHORSEPOV
,_ ,_™.__*.™.™»^.__
.
.
•
•
i - r r
^^— — '
2)
\NERR
r
**„
21.
«ERRE
* !
T •
...»^»..^...
! i
-_-,,^««A-^.
* *
i 1
^H"-
(1-1/2) J
? i
r f r
— — •*— -j—
i [
j£*~\
M. i /2V'
!
OUlREDi —
-1 i
1 1
I
• j
-—« r— 4— -
(
1
j
f
!
—
—
-«.
„,
...
"7 — j--
-f-l-
44-
* t
..4.1.
-4-j-
ii-
1t
IS
r~™f*i-"t
4 ^
-4-f.
ii
It
1 t
i-i
i
•|l
10
30
50
70 100
FLOW (J/min)
300
500
1000
l/min x 0.2642 - gpm
hp x 0.7457 = kW
243
-------
TABLi 44, INSTALLED-PIPE COSTS
TYPE
ABS-PVC
STAINLESS STEEL #304,
SCHEDULE 40
STAINLESS STEEL #316,
SCHEDULE 40
STEEL, SCHEDULE 40
DIAMETER
em
3.8
5.1
7.8
10.2
IS.2
5.1
7M
10.2
S.1
7j6
10.2
10,2
12.7
15.2
20.3
in.
1-1 12
2
3
4
6
2
3
4
2
3
4
4
S
6
8
corns*
PERMETiR n
1?
If
2S
38
eo
70
12S
213
82
146
250
S?
98
114
160
PER FOOT
5
6
8
9
18
21
38
64
25
44
7S
20
29
34
48
244
-------
factory-assembled, skid-mounted units. The use of such
equipment generally entails considerably lower installation
costs than if the entire system were field-assembed.
Further, most of the equipment modules, (e.g., tanks and
thickeners) are relatively small, which also tends to result
in relatively low installation costs.
Ca.Ei.tal Cost of Contingency and Contractor * s Fee
This cost is computed as 20% of the sum of the costs for
facilities and equipment, including installation.
Annual Cost of amortization
Annual depreciation and capital costs are computed as
follows:
CA = B(r) (1 +r)n
(1 + r}n - 1
where CA = Annual cost
B = Initial amount invested
r = Annual interest rate
n » Useful life in years
The computed cost is often referred to as the capital
recovery factor. It essentially represents the sum of the
interest cost and depreciation.
An interest rate of 10S is used. The expected useful life
of facilities and equipment is 10 years. No residual or
salvage value is assumed.
Annual cost of operation and Maintenance
General. Plant operations are assumed conducted 24 hours
per day, 350 days per year.
Operating Personnel. Personnel costs are based on an hourly
rate of $12.00. This includes fringe benefits, overhead and
supervision (Reference 18). Personnel are assigned for
specific activities as required.
Facility Repair and Maintenance. Facility repair and
maintenance are included as 3% of facility costs.
245
-------
Equipment Repair and Mai ntenance. The cost of -these
activities is estimated as 5% of installed equipment costs,
Materials. The materials employed in the pretreatment
processes and their costs are shown below.
Hydrated Lime (Calcium Hydroxide) $55/metric ton ($50/short ton)
Plocculant $2/kg ($4/lb)
Filter Md (Diatomaceous earth) $0»264/kg ($0.58/lb)
Calcium Chloride (80S) $75/metrie ton ($68/short ton)
Caustic Soda (Sodium Hydroxide) $425/metric ton ($385/short ton)
Sulfuric Acid $55/metric ton ($50/short ton)
Sulfur Dioxide $190/metric ton ($170/short ton)
The cost of manufactured chemicals in S/metric ton ($/short
ton) used to assess the potential economic impact of the
pretreatment costs are:
Aluminum Chloride $198 (180) Nickel Sulfate $ 1,672 (1,516)
Aluminum Sulfate 98 (89) Nitrogen and Oxygen 40 (36)
Calcium Carbide 188 (170) Potassium Bichromate 1,254 (1,137)
Calcium Chloride 60 (54) Potassium Iodide 8,270 (7,500)
Copper (Cupric) Sulfate 835 (760) Silver Nitrate 90,000 (82,000)
Iron (Ferric) Chloride 100 (90) Sodium Bicarbonate 180 (163)
Lead Monoxide 530 (480) Sodium Fluoride 640 (580)
The costs are based on vendor quotations and prices
published in the Chemical Marketing Reporter.'
Taxes and Insurance. The combined costs are included as 4%
of the total investment cost.
Sludge Disposal. Disposal costs can vary widely. Chief
cost determinants include the amount and type of waste, on-
site vs. contractor disposal, size of the disposal
operation, and transport distances. The following disposal
costs are employed in this study.
Chemical landfill $0.05/1 ($0.19/gal)
Sanitary landfill $5.00/metric ton ($4.55/short ton)
Annual cost of Electricity
Energy (electricity) costs are based on the cost per
horsepower-year computed as follows:
Cy = 1.1 'HP. x 0.7457 x Hr x CkW
E x -P
where
Cy = Cost
246
-------
• HP = Total horsepower rating of motors (1 hp=
0,7457 JcWJ
E = Efficiency factor (0,9)
P = Power factor (0.9)
Hr = Annual operating hours (as applicable)
ckW = cost per kilowatt-hour of electricity
($0.03)
Hotes 1.1 factor represents allowance for miscellaneous
energy use.
-------
Page Intentionally Blank
-------
IX
PRACTICABLE TECHNOLOGY
INTRODtJCTIQN
The recommended pretreatment standards to be achieved are
based on the ability of POTW to alter or remove certain
waste water pollutants — most notably, pH and total suspended
solids (TSS) , respectively — and on the chemical producers'
application of pretreatment technologies in keeping with the
best practicable control technology currently available
(BPCTCAJ to remove pollutants which are not effectively
treated within a PQTW. For the 14 inorganic chemical
subcategories covered by this document, , these levels of
technology are based on:
(1) The average of the best existing performance of
facilities of various sizes discharging to POTw,;
The performance of facilities discharging directly
to surface waters ; and
The performance of similar treatment systems in
other industries.
Consideration was also given to:
(1) The total cost of application of technology in
relation to the ef fluent* reduction benefits to be
achieved from such application;
(2) Process employed;
(3) Engineering aspects of the application of various
types of control techniques;
Nonwater-quality environmental impact (including
solid- waste generation and energy requirements) ;
(5) Incidental pollutant removals achieved within
(6) Toxicity of various pollutants relative to a POTWj
and
(7) influent limitations .imposed by PGTW.
Pretreatment technology emphasizes treatment facilities at
the end of chemical process. Excluded from this technology
are control practices available to significantly reduce or
2*9
-------
eliminate process waste water discharges. These control
practices which include process controls, recycle,
alternative uses of water, and recovery and reuse of some
waste water constituents, are discussed in Section VII for
each subcategory.
The remainder of this section discusses, for each chemical
subcategory, the pollutant parameters deteremined to be
significant, the recommended pretreatment standard for each
of these pollutants, and the rationale for achievement of
the recommended standards.
Within this section, each subcategory is treated separately
for recommendation of pretreatment standards.
Aluminum Chloride Subcateqgry
This subcategory includes those plants producing hydrous and
anhydrous aluminum chloride, except where the salt is
produced as an intermediate for synthesis of other products.
The significant pollutant parameter for this subcategory,
and pretreatment standard for that parameter is shown below.
Effluent Effluent
Characteristics Limitations
pH Within the range 5.0 to 10.0
At anhydrous aluminum chloride plants using scrap aluminum
as a raw material, zinc concentration can be expected to be
similar to concentrations which occur in secondary aluminum
scrubber waste water. Control of zinc may be required at
the local level to protect POTW operation. As guidance for
local POTW authorities, zinc limitations of 2.5 mg/1 (30 day
average) and 5.0 mg/1 (daily maximum} are recommended. This
limit can be met by lime treatment and settling.
Aluminum in the discharge from aluminum chloride producing
plants is acceptable in municipal treatment systems when it
occurs in low concentrations. At higher concentrations it
can cause excessive sludge bulking in a POTW. Because
aluminum is relatively insoluble at neutral pH, a pH limit
from 5.0 to 10.0 has been established for the purpose of
limiting aluminum discharges. The cost of this treatment is
estimated at from 1.6 to 3.5 percent of product price.
Aluminum Sulfate Subcategory
This subcategory includes those plants producing solid and
liquid aluminum sulfate (including iron-free alum) except
plants where the alum is produced as an intermediate for
250
-------
manufacture of other products. The significant pollutant
parameter for this subcategory, and pretreatment standard
for this parameter is shown below.
Pollutant or Pretreatment
Pollutant Property Standard
Maximum for Average of daily
any one day values for thirty
'consecutive days
shall,, not exceed
mg/1
Zinc 5.0 2.5
Zinc may be present in discharges from aluminum sulfate
plants in sufficient amounts to interfere with PQTW
operation, The zinc standard can be met by pH adjustment
and settling. Aluminum in the discharge from aluminum
sulfate plants is acceptable when it occurs at low
concentrations. High concentrations of aluminum can cause
sludge bulking in a POTW. Pretreatment for control of mine
will also reduce aluminum concentrations to acceptable
levels. -The cost of tMs treatment is estimated at 0.5 to
4.8 percent of product price.
Calciuin Carbide Subca-teggry
This subcategory includes the production of calcium carbide
in open furnaces. The significant pollutant parameter is
suspended solids in the range of 50 to 750 mg/i. Suspended
solids at these levels . will not interfere with ' POTW
operation, and will receive adequate treatment. Since no
suspended solids limit is imposed, .there is no treatment
cost,
Calcium Chloride subcateqory . •
This subcategory includes those plants producing calcium
chloride from all sources. Since wastes contain only
calcium and sodium brines that will not interfere with
municipal systems, no limitations are established and no
costs will be incurred.
(Cuprie) gulf ate Subca-tecyory
This subcategory includes the manufacture of copper (cupric)
sulfate in crystal and solution form. Significant pollutant
251
-------
parameters for this subeategory, and pretreatment standards
for these parameters, are shown below.
Pollutant or Pretreatment
Pollutant Property Standard
Maximum for Average of daily
any one day values for thirty
consecutive days
J shall not exceed
mg/1
Copper 1.0 0.5
Nickel 2.0 1.0
The copper sulfate manufacturing industry recycles almost
all process waste waters. The waste source is from plant
spills and wash downs. The standards can be readily
achieved by lime neutralization and settling as is shown in
data from plant 19505, This plant achieves an average
copper concentration of 0.48 mg/1. the cost of treatment
for this system is estimated at 0,2 percent of the product
price.
Ferric chloride Subcategory
This subcategory includes plants which produce both ferric
chloride solution and ferric chloride hexahydrate crystals
from iron and steel pickling liquors. It does not include
production of ferric chloride by passing chlorine gas over
iron at red heat, or by oxidizing anyhdrous ferrous chloride
with chlorine. Significant pollutant parameters for this
subcategory, and pretreatment standards for these
parameters, are shown below.
Pollutant or Pretreatment
Pollutant Property Standard
Maximum for Average of daily
any one day values for thirty
consecutive days
shall not exceed
tug/I
Total Chromium 1.8 0.9
Hexavalent Chromium 0.18 0.09
Copper 1.0 0.5
252
-------
Nickel 2.0 1,0
Zinc 5.0 2.5
The major source of pollutants in waste water generated from
ferric chloride production is the pickle liquor feed. The'
pickle liquor contains .a variety of trace elements,
including chromium, copper, nickel, and zinc, all of which
may prove detrimental to POTW operation, and may pass
through the treatment system without adequate removal. The
standards can be- achieved by lime neutralization and
settling. The cost of treatment for this system is
estimated to be from 2.0 to 5.6 percent of product price*
Lead Monoxide gubcategory
This subeategory includes all manufactuirng operations which
produce lead monoxide. The significant pollutant parameter
selected for this subcategory, and pretreatment standards
recommended for this parameter, is shown below.
Pollutant or Pretreatment
Pollutant Property ' standard r = ......... *
Maximum for Average of daily
any one day values for thirty
consecutive days
. hajll ..... ot exceed
mg/1
Lead 2.0 1.0
The best practicable control technology currently available
for the control of waste water from this subcategory is no
discharge of process waste water. . This is currently being
accomplished at most lead monoxide plants by dry dust
control and cleanup practices.- Only those plants employing
wet washdown practices will produce a process waste water
having the characteristics of high suspended-solids and lead
concentrations. No limit is set on suspended solids
concentrations, as suspended solids will be adequately
removed in a POTW. Lead is toxic to plants and animals, and
can inhibit POTW operations. Lead can be removed from
solution by pH adjustment and settling. One lead monoxide
manufacturing plant is achieving lead removals down to O.f
mg/1 using sulfate precipitation and settling. Lime is more
commonly used for lead removal, and residual lead con-
centrations of about 1 mg/1 are attainable using this
253
-------
precipitating agent. The cost of treatment for this system
is estimated to be 0,4 percent of product price.
Nickel Sulfate Subcategory
This subeategory includes those plants which produce nickel
sulfate solution and nickel sulfate crystals from nickel,
nickel oxide, and impure nickel-bearing materials.
Significant pollutant parameters selected for this
subcategory, and pretreatment standards recommended for
these parameters are shown below.
Pollutant or Pretreatment
Pollutant Property • standard
Maximum for Average of daily
any one day values for thirty
consecutive days
shall not exceed
mg/1
Nickel 2 1
Copper 1.0 0.5
Nickel and copper, the parameters of concern in nickel
sulfate, can inhibit POTW operations, and can pass through
the treatment plants without adequate treatment. Chemical
precipitation, settling, and filtration will produce an
effluent that meets the limits for copper and nickel.
Nickel reductions to 0.5 mg/1 have been reported using
chemical precipitation with soda ash and settling. The cost
of treatment for this system is estimated to be from 0.2 to
1,3 percent of product price.
Nitrogen and Oxygen subcategory
This subcategory covers all industrial plants producing
nitrogen and oxygen via air separation. Excluded are those
plants utilizing the Linde process of molecular sieves, and
also those plants (classified as "filling stations") which
do not actually manufacture the gases but, rather, convert
liquid nitrogen and oxygen to gaseous products for
commerical distribution. Process wastes from this
subcategory are characteristically small volumes of
compressor condenstate, which results when the water vapor
portion of atmospheric air condenses within compressor. Oil
and grease may become a part of this stream as the
condensate comes into contact with the internally lubricated
254
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parts of the compressor. The volume of water generated is
usually less than 7000 gallons per day, and will not contain
sufficient oil and grease to cause any,adverse effects at a
POTW. For this reason no limit is set for oil and grease.
Since no pretreatment is required, there will be no cost to
the industry.
Potassium pichroatate SubcategorY
THis subeategory includes production of potassium dichromate
by reaction of sodium dichromate with postassium chloride.
Significant pollutant parameters for this subcategory, and
pretreatment .standards for those parameters, are shown
below.
Pollutant or Pretreatment
Pollutant Property ' . Standard •
Maximum for Average of daily
any one day values for thirty
consecutive days
i • shaljl not^exceed
mg/1
Hexavalent chromium 0.18 0.09
Total chromium 1.8 0,9
The pollutant of concern is chromium which is soluble and
potentially very harmful in its hexavalent form. Treatment
for chromium removal consists of treatment with sulfur
dioxide to reduce the hexavalent chromium to its trivalent
state and neutralization, precipitation, and solids
separation to remove the trivalent chromium. Estimated cost
for this treatment are 2,1 percent of product price.
Potassium Iodide Subcategory
This subcategory is composed of four domestic manufacturers.
Three slightly varying production processes are employed by
this industry, and these have been described in Section III
of this document. No pretreatment standard is required for
this subcategory as discussed below. Discharge from the
industry subcategory generally consists solely of non
contact cooling water, and extremely snail quantities of
water used for equipment washdowns or cleanup of spills,
Because of the nature of the waste water and the small
amount generated, no effluent limitations are necessary for
255
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this siabeategory and no costs ' will be incurred by the
industry.
silver Nitrate Subcatecrory
This subcategory includes all plants producing silver
nitrate. The significant pollutant parameter for this
subcategory, and the pretreatntent standards for that
parameter are shown below.
Pollutant or Pretreatment
Pollutant Property Standard
Maximum for Average of daily
any one day values for thirty
• consecutive days •
shall_not exceed
mg/1
Silver 1.0 0.5
Silver is extremely toxic to microorganisms and can cause
inhibition of the activated sludge process. Because of its
toxicity, a limit of 1.25 mg/1 (30 day average) is
established. This is achievable by chlorination, chemical
precipitation with lime and a flocculating agent, and
settling or filtration. The cost of the treatment is
estimated to be from 0.007 to 0.03 percent of the product
price.
sodium Bicarbonate Subcate
-------
Pollutant or Pretreatstent
Pollutant Property , Standard
Maximum for Average of daily
any one day values for thirty
consecutive days
shallOfiot exceed
mg/1
Fluoride 50.0 25.0
Fluoride is recognized as a-material potentially toxic to
fish, wildlife, livestock, and humans, it would
through a PQTW without being treated or removed. Fluoride
concentrations in excess of 10,000 mg/1 are found in raw
waste water from sodium fluoride production. Treatment
technologies for fluoride removal include?
precipitation/neutralization, floceulation, settling, and
filtration. The cost of'this treatment system is estimated
at 3.8 percent of product cost.
257
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SECTION X
ACKNOWLEDGMENTS
The Environmental Protection Agency would like to
acknowledge the contributions of calspan corporation under
the direction of Dr. P. Michael Terleeky, Jr. and
Mr. Robert Lochemer for their aid in the preparation of this
document.
The Project Officer, Elwood E. Martin would like to thank
his associates in the Effluent Guidelines Division, namely
Mr. Walter J. Hunt and Mr. Richard P. Gigger for their
valuable suggestions and assistance.
Acknowledgement and appreciation is also given to
Ms. Kaye Starr, Ms. Pearl Smith and Ms. Carol Swann for
their efforts in the report preparation.
Appreciation is extended to the following members of the
Environmental Protection Agency Working Group for their
review and suggestions on this report:
Mr, Walter J. Hunt, Effluent Guidelines Division, chairman
Mr. Elwood 1. Martin, Effluent Guidelines Division,
Project Officer
Mr. Richard P. Gigger, Effluent Guidelines Division
Ms, Lee Breckenridge, Office of General Counsel
Ms. Madeline Nawar, Office of Water Enforcement
Mr, Sammy K. Ng, Office of Analysis and Evaluation
Dr. Barbara Elkus, Office of Analysis and Evaluation
Mr. Steve Weil, Office of Planning and Evaluation
Appreciation is also extended to the following trade
associations and individual corporations for assistance and
cooperation during the course of the program:
Allied Chemical Corporation
J.T, Baker Chemical Company
Chemetron corporation
Chemical 6 Pigment Company
Cities Service Co., Inc.
Dow Chemical U.S.A.
Eagle-Picher Industries, Inc.
Eastman Kodak Company
The Greyhound Corporation
Liquid Air Corporation of North America
Midwest Carbide Corporation
M 6 T Chemicals, Inc.
Pearsall Chemical Corporation
259
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Phelps Dodge Corporation
Onion Carbide Corporation
Van Waters 8 Rogers
The assistance of Regional Offices of the USEPA is also
greatly appreciated.
260
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SECTION XI
REFERENCES
1. The Directory of Chemical Mginuf_acrturerg—OSA, Stanford
Research Institute, 1974.
2. Industrial Chemicals, 3rd id., W.L. Faith, D.B. Keyes,
and R.L. Clark, John Wiley and Sons, New York, 1965.
3. Chemical Process Industries, Third ED., R.N. shreve,
McGraw-Hill Book Co., Inc., 1967.
1. "Development Document for Effluent Limitations
Guidelines and New Source Performance Standards for the
Major Inorganic Products Segment of the Inorganic
Chemicals Manufacturing Point Source Category." Effluent
Guidelines Division, U.S. Environmental Protection
Agency, Washington, EPA-4i|0/l-74-OQ7-A.
5. "Development Document for Effluent Limitations
Guidelines and New Source Performance Standards for the
Significant Inorganic Products Segment of the Inorganic
Chemicals Manufacturing point Source Category," Effluent
Guidelines Division, U.S. Environmental Protection
Agency, Washington, EPA-4HO/1-75-037, 1975.
6. "Industrial Inorganic chemicals, N.E.C., Sic 2819,
. Preliminary . Report," 1972 census of. Manufacturers,
Industrial Series, M,C7'2 (P)-28A-U, Bureau of the Census,
U.S. Department of Commerce, December 1973.
7. "Industrial Inorganic Chemicals, Industrial Gases, sic
2813, Preliminary Report," 1972 Census of Manufacturers,
Industrial Series, MC72 (PJ-28A-4, Bureau of the Census,
O.S. Department of Commerce, December 1973.
8- tJ.S. Pharmacopeia, 17th Ed., 1965. -
9- Advanced Wastewater Treatment, R.L. Culp and G.L. Gulp,
Van Nostrand Reinhold Co., New York, 1971.
10. "The Solubility of Heavy Metal Hydroxides in Water,
Sewage, and Sewage Sludge-I, the Solubility of Some
Metal Hydroxides," s.H. Jenkins, D.G. Keight, and R.E.
Hamphrey, Journal on Air and Water Pollution, NO. 8, pp.
537-556, 196i».
11. "Base Metal Mine Waste Management in Northeastern New
Brunswick," Environmental Impact and Assessment Report
261
-------
EPS 8-WP-73-1, Water Pollution Control Directorate,
Environment Canada, Ottawa (Ont.). Canada, June 1973.
12. "Development Document for Effluent Limitations
Guidelines and Standards of Performance for the Ore
Mining and Dressing Industry Point Source Category,"
U.S. Environmental Protection Agency, Washington, D»C.
13. Miller, D.G.f "Fluoride Precipitation in Metal Finishing
Waste Effluent," in Water-1974; I± Industrial Waste
Treatment, AICBE Symposium Series, Vol. 70, No.
14. Parker, C.L. and Tong, C.C., "Fluoride Removal:
Technology and Cost Estimates," Industrial Wastes,
November/December 1975, pp. 23-27.
15. Rohrer, L., "Lime, CaCl2 Beat Fluoride Wastewater,"
Water and Wastes Engineering, November 1974, pp. 66-68.
16. Zabben, W. and Jewett, H.W., "The Treatment of Fluoride
Wastes," • Proceedings of 22nd Industrial Waste
Conference, Purdue University, May 2-4, 1967, pp.- 706-
716.
17* "State and Local Pretreatment Programs, Vol. 1- Federal
Guidelines (Draft)," U.S. Environmental Protection
Agency, Washington, D.C., August 1975.
18. "Building Construction Cost Data 1975," Robert Snow
Means Company, Inc., 33rd Edition.
19. "Supplement for Pretreatment to the Interim Final
Development Document for the Secondary Aluminum Segment
of the Nonferrous Metals Manufacturing Point Source
Category," Effluent Guidelines Division, O.S.
Environmental Protection Agency, Washington, D.C., EPA-
440/1-76/081C, December 1976.
20. Quality Criteria for Water, U.S. Environmental
Protection Agency, Washington, D.C., EPA-440/9-76-023.
21. Patterson, J.W. and Minear, R.A,, Waste Water Treatment
Technology, (Draft), Illinois Institute of Technology,
January, 1973.
22. "Pretreatment Standards for Selected Pollutant
Parameters, (Draft)," Sverdrup & Parcel and Associates,
Inc., Prepared for U.S. Environmental Protection Agency,
February, 1977.
262
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SECTION XII
GLOSSARY
Acetylene/- A gas (chemical formula - C2H2) which can be
prepared by the action of water on calcium carbide. The
starting material for large-scale synthesis of important
organic compounds.
Activated-sludge' Process - A biological waste water-
treatment process which involves the generation, under
aerobic conditions, of organisms capable of decomposing
organic material present in municipal waste water. The
sludge produced is subsequently removed from the treated
waste water by sedimentation and wasted or used as seed
material in subsequent treatment.
Alcyicide - Any substance which kills algae or controls its
growth.
Alum - Technically, a double sulfate of ammonium or a
univalent or trivalent metal but commonly used to denote
aluminum sulfate - A12(SOf*)3..
Arc Furnace - A furnace heated by the "arc" produced between
electrodes.
Atmospheric Crystallizer - Apparatus used to carry out
crystallization under ambient pressure,
Bagjiouse - Apparatus for cleaning dusts and other
particulates from a gas stream.
•Barometric Condenser - A jet condenser in which water and
the vapor to be condensed are in direct contact. The
condenser is set sufficiently high so that the water drains
from it by a barometric hot leg.
Bauxite - The principal ore of aluminum, composed of
aluminum hydroxides and impurities in the form of free
silica, clay, silt, and iron hydroxides.
Batch Process - Any discontinuous process which proceeds
stepwise in a timed sequence, as opposed to a continuous
process in which all steps proceed simultaneously without
interruption.
plowdown - The use of compressed air and/or liquid (usually,
water) under pressure to remove liquids and solids from a
263
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vessel {i.e., cooling towers, emission scrubbers,
compressors, boilers).
Carbona-tion - The process by which a solution is impregnated
with carbon dioxide to produce a carbonate or bicarbonate.
Caustic Soda - A common name for sodium hydroxide (NaOH).
Centrifugal Compressor - Type of nan-lubricated compressor
utilized in those processes requiring low-pressure
conditions for effective compression.
Centrifugation - A physical operation involving the
separation of suspended solids {such as crystals) from a
mixture of liquid and suspended solids by centrigual force.
Compressor Condensate - Moisture trapped within a compressor
when the water-vapor portion of atmospheric air is subjected
to high-pressure effects.
Cooling Tower - Towers which accomplish the cooling of water
circulated in the tower by moving ambient air through the
tower. The air/water contact causes some of the water to "be
evaporated by the air. Thus, through latent heat transfer,
the remainder of the circulated water is cooled.
Crystallization - Process of forming crystals from a
solution.
Decant - To remove the liquid portion of a settled mixture
without disturbing the sediment.
Demagging - The process by which magnesium is removed from
molten aluminum through techniques such as injection of
chlorine.
Fil-fcer Backwash - The reversal of flow through a filter to
wash clogged material out of the filter medium and reduce
conditions causing loss of head.
Filter Cake - The dewatered sludge discharged from a filter.
Contains 65 to 80% moisture, depending on the type of
sludge, dewatering equipment, and the conditioning of the
sludge.
Filter press - An apparatus which separates a thick mixture
into liquid (filtrate) and solids (filter sludge caKe). by
compressing the sludge.
Filtrate - The effluent or liquid portion of a mixture ,of
solids and liquid removed by or discharged from a filter.
264
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Fusion - The union of two chemical species by melting.
Heat Exchanger - A device providing for the transfer of heat
from a fluid flowing in tubes to another fluid outside the
tubes or the reverse.
Ion Ixchangg - Involves the displacement of ions of given
species from insoluble exchange materials by ions of
different species in solutions. The process can be used to
remove ionic pollutants from waste water,
Double-column Rectifier ' - System of fractional distillation
employed - in the air- separation process to effectively
separate compressed, purified air into liquified components
of nitrogen and oxygen.
Electric Furnace - A furnace heated by electric coils.
Electrolyte - Materials which, when placed in solution, make
the solution conductive to electrical currents.
Evaporator - Apparatus used to reduce or remove water from a
solution to concentrate the desired product.
Litharge - A common name for lead monoxide or yellow lead
(Pbo) .
Linde Process (via molecular .sieves) - An alternative
technology employed for air separation which is particularly
adaptable to those facilties having low product demand, such
as waste water treatment plants and small industrial
complexes. High-purity oxygen is produced by compressing
air and then purifying and separating it through a series of
vessels containing granular adsorbent (molecular sieve) ,
Mother Liquor - A concentrated solution substantially freed
from undissolved matter by filtration, centrifugation, or-
decantation, 'Crystals are formed from the mother liquor,
Mult i- E f f ect gyapgrator - In -chemical . processing
installations requiring ' a series of evaporations • and
condensations, the individual units are set up in series,
and the latent heat of vaporization from one unit (or
effect) is used to supply energy for the next.
Separator - An apparatus used to physically
separate several constituents or components of a solution
based on density differences,
Non contact CoolJng Water - Cooling water which does not
come into contact with the materials being cooled.
265
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Oxidizing Tower - A process tank where oxidation reactions
occur.
Pretreatment - The necessary processing given to materials
before they can be properly utilized or treated in a process
or treatment facility.
Primary Treatment - Major treatment, and sometimes the only
treatment in a waste-treatment works, usually sedimentation
and/or flocculation. Attains removal of a moderate
percentage of suspended matter but little or no colloidal or
dissolved matter.
POTW - Publicly owned Treatment Works.
Reciprocating compressor - Type of compressor which utilizes
a rod-andpiston mode of operation for efficient compression
of material. May be designed either single- or multi-stage,
depending on compression needs. A distinguishing
characteristic of this compressor is the need for oil
lubrication of the cylinder compartments.
Reversing Exchangers - Heat-exchange unit which serves to
purify compressed air by the removal of carbon dioxide and
water vapor.
Screening - Process used to segregate solid material into
various sizes.
Scrubber - Apparatus used in gas cleaning in which the gas
is passed through packing or spray.
Secondary Treatment - Treatment of wastes by biological or
chemical methods after primary treatment by
flocculation/sedimentation. Secondary treatment depends
primarily upon biological aerobic organisms for the
biochemical decomposition of organic solids to inorganic or
stable organic solids.
Sedimentation - The deposition of suspended matter in
liquids, wastes, etc., by gravity. It is usually
accomplished by reducing the velocity of liquid flow below
the point where suspended material will be transported.
Settling Pond - A pond, natural or artificial, for
recovering solids from an effluent.
Sludge - A viscous waste, with a high solids content,
resulting from a number of waste water treatment processes
(i.e., filtration, sedimentation, etc.).
266
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Slurry - A watery mixture or suspension of solids (such as
mudf lime, sludge) .
Soda Ash - Common name for sodium carbonate (Na_2CO3).
Solvay Process - This process for producing soda ash (sodium
carbonate) involves a reaction (under pressure) between
ammonia, brine (mostly Nad), and carbon dioxide to yield
sodium bicarbonate. The sodium bicarbonate is heated to
yield soda ash.
Sublimation - The process by which a solid transforms
directly to its vapor without passing through the liquid
state,
Supernatant - The liquid standing over a precipitate.
Vacuum Crystallizer - Apparatus for increasing the rate of
crystallization through the use of pressure.
yenturi Scrubber - A device for the removal of particulates
from a gas stream. The particulate-laden stream is directed
through a venturi tube at a certain throat velocity. Water
sprays are introduced just ahead of the venturi throat. The
water and particles are then removed from the gas.
Washdown - Water resulting from cleaning of equipment,
walls, floors, etc., within a plant.
Zeolite Process - An ion-exchange process for softening
water. The zeolite exchanges sodium ions for hardness
constituents (calcium, magnesium, etc.) in the water.
267
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CONVERSION TABLE
MULTIPLY UNITS) by TO OBTAIN (METRIC UNITS)
ENGLISH UNIT ABBREVIATION , ABBREVIATION UNIT
acres
acre - feet
British Thermal
Units
British Thermal
Units/pound
cubic feet
cubic feet
cubic feet/ minute
cubic feet/second
cubic inches
cubic yards
degrees Fahrenheit
feet
flask of mercury
gallons
gallons
gallons/day
gattons/rninute
horsepower
inches
inches of mercury
miles (statute)
million gallons/ day
ounces (troy)
pounds
pounds/square
inch (gauge)
pounds/square
inch (gauge)
square feet
square inches
tons (short)
tons (long)
yards
ac
acft
BTU
BTU/lb
cuft
cuft
cfm
cfs
cu in.
cu y
oF
ft
(76.5 Ib)
gal
gal
gpd
gpm
••hp
in.
in. Hg
mi
mgd
troy oz
Ib
psig
psig
set ft
«jin.
t
loagt
y
0,405
1,233.5
0.252
0.555
0.028
28.32
1.7
16.39
0.76456
. 0.555 (OF-32)1
0,3048
34.73 1
0.003785
3.785
0.003785
0.0631
0.7457
. 2.54
0.03342
L609
3,785 l
31.10348
0.454
(0,06805 psig+1)1
5.1715
0.0929
6.452
. 0.907
1.016
0.9144
ha
cu m
kg cal
kg cal/kg
cum
1
cu m/rnin
cu m/min
cu cm (or cc)
cu m
°c
rn
kgHg
cum
1
cu m/day
I/sec
kW
cm
atm
km
cu m/day
£
kg
atm
cm Hg
sqm
sqcm
kkg
kkg
m
hectares
cubic meters
kilogram - calories
kilogram calories/kilogram
cubic meters
liters
cubic meters/minute
cubic meters/minute
cubic centimeters
cubic meters
degrees Celsius
meters
kilograms of mercury
cubic meters
liters
cubic meters/day
liters/second
kilowatts
centimeters
atmospheres
kilometers
cubic meters/ day
grams
kilograms
atmospheres (absolute)
centimeters of mercury
square meters
square centimeters
metric tons (1000 kilograms)
metric tons (1000 kilograms)
meters
1
Actual conversion, not a multiplier
-------
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
2.
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Supplement for Pretreatment to the Development
Document for the Inorganic Chemicals Point Source
Category
B. REPORT DATE
July. 1977 - Approval Date
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
Elwood E. Martin
Project Officer
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Effluent Guidelines Division
Office of Water and Hazardous Materials
U.S. Environmental Protection Agency
Washington, D. C. 20460
1O. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
68-01-3281
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. Environmental Protection Agency
401 M Street, S. W. (WH-552)
Washington, D. C. 20460
13. TYPE OF REPORT AND PERIOD COVERED
Interim Final Regulations
H47 SPONSOR ING AGENCY CODE
EPA-E6D
IS. SUPPLEMENTARY NOTES
16. ABSTRACT
This document presents the findings of a study by the Environmental Protection
Agency of the inorganic chemical industry for the purpose of developing
pretreatment standards for existing sources to implement section 307{b) of the
Federal Water Pollution Control Act, as amended.
The development of data and identified technology presented in this document
relate to wastewaters generated in the following specific segments of the
inorganic chemical industry; aluminum chloride, aluminum sulfate, calcium
carbide, calcium chloride, copper sulfate, ferric chloride, lead oxide, nickel
sulfate, nitrogen, oxygen, potassium dichromate, potassium iodide, silver nitrate,
sodium bicarbonate, and sodium fluoride. The pretreatment levels corresponding
to these technologies also are presented.
Supporting data and rationale for development of pretreatment levels based on
best practicable pretreatment technology are contained in this report.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COS AT I Field/Group
Industrial Wastes, Pollution, Aluminum
Halides, Aluminum Sulfate, Potassium
Chromates, Copper Sulfate, Iron Chloride,
Lead Oxides, Nickel Sulfates, Silver
Nitrate, Sodium Fluoride
Manufacturing Processes
Pretreatment
18. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (ThisReport/
Unclassified
21. NO. OF PAGES
282
20. SECURITY CLASS (Thispage}
Unclassified
22. PRICE
EPA form 2220-1 (Re», 4-77) PREVIOUS EDITION is OBSOLETE
* V. S, GOVEBNMEKT PMNTWO OFFICE : 19T7 2«-802/6553
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U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 204«0
POSTAGE AND FEES PAID
ENVIRONMENTAL PROTECTION AGENCY
EPA-33S
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